WorldWideScience

Sample records for saturee etude experimentale

  1. Etude theorique et experimentale des evaporateurs de dioxyde de carbone operant dans des conditions de givrage

    Science.gov (United States)

    Bendaoud, Adlane Larbi

    Les evaporateurs de refrigeration sont surtout du type tube a ailettes, appeles serpentins, et fonctionnent dans l'une des conditions suivantes: seche, humide ou avec formation de givre. Il a ete demontre que la formation du givre sur la paroi exterieure de l'echangeur engendre une surconsommation energetique a cause des operations de degivrage puisque 15 a 20% seulement de la chaleur produite sert au degivrage tandis que le reste est dissipee dans l'environnement [1]. Avec l'avenement des nouveaux refrigerants, moins nocifs envers l'environnement, l'industrie du froid se trouve penalisee du fait que peu ou pas de composantes mecaniques (compresseur, pompe, echangeur...etc.) adaptees sont disponibles [3]. Il s'agit pour la communaute des frigoristes de combler ce retard technologique en redeveloppant ces composantes mecaniques afin qu'elles soient adaptees aux nouveaux refrigerants. Dans cette optique, et afin de mieux comprendre le comportement thermique des evaporateurs au CO2 fonctionnant dans des conditions seches, qu'un groupe de chercheurs du CanmetENERGIE avaient lance, en 2000, un programme de R & D. Dans le cadre de programme un outil de simulation des evaporateurs au CO2 a ete developpe et un banc d'essai contenant une boucle secondaire de refrigeration utilisant le CO2 comme refrigerant a ete construit. Comme continuite de ce travail de recherche, en 2006 ce meme groupe de recherche a lance un nouveau projet qui consiste a faire une etude theorique et experimentale des evaporateurs au CO2 operants dans des conditions de givrage. Et, c'est exactement dans le cadre de ce projet que se positionne ce travail de these. Ce travail de recherche a ete entrepris pour mieux comprendre le comportement thermique et hydrodynamique des serpentins fonctionnant dans des conditions de givrage, l'effet des circuits de refrigerant ainsi que celui des parametres geometriques et d'operation. Pour cela, un travail theorique supporte par une etude experimentale a ete effectue

  2. Etude numerique et experimentale de la reponse vibro-acoustique des structures raidies a des excitations aeriennes et solidiennes

    Science.gov (United States)

    Mejdi, Abderrazak

    Les fuselages des avions sont generalement en aluminium ou en composite renforces par des raidisseurs longitudinaux (lisses) et transversaux (cadres). Les raidisseurs peuvent etre metalliques ou en composite. Durant leurs differentes phases de vol, les structures d'avions sont soumises a des excitations aeriennes (couche limite turbulente : TBL, champs diffus : DAF) sur la peau exterieure dont l'energie acoustique produite se transmet a l'interieur de la cabine. Les moteurs, montes sur la structure, produisent une excitation solidienne significative. Ce projet a pour objectifs de developper et de mettre en place des strategies de modelisations des fuselages d'avions soumises a des excitations aeriennes et solidiennes. Tous d'abord, une mise a jour des modeles existants de la TBL apparait dans le deuxieme chapitre afin de mieux les classer. Les proprietes de la reponse vibro-acoustique des structures planes finies et infinies sont analysees. Dans le troisieme chapitre, les hypotheses sur lesquelles sont bases les modeles existants concernant les structures metalliques orthogonalement raidies soumises a des excitations mecaniques, DAF et TBL sont reexamines en premier lieu. Ensuite, une modelisation fine et fiable de ces structures est developpee. Le modele est valide numeriquement a l'aide des methodes des elements finis (FEM) et de frontiere (BEM). Des tests de validations experimentales sont realises sur des panneaux d'avions fournis par des societes aeronautiques. Au quatrieme chapitre, une extension vers les structures composites renforcees par des raidisseurs aussi en composites et de formes complexes est etablie. Un modele analytique simple est egalement implemente et valide numeriquement. Au cinquieme chapitre, la modelisation des structures raidies periodiques en composites est beaucoup plus raffinee par la prise en compte des effets de couplage des deplacements planes et transversaux. L'effet de taille des structures finies periodiques est egalement pris en

  3. Etude experimentale des excitations topologiques de l'effet Hall quantique a nu = 1 dans les heterostructures semiconductrices a double puits quantique

    Science.gov (United States)

    Charlebois, Serge

    De nombreux travaux theoriques et experimentaux ont ete publies sur les excitations topologiques de gaz electroniques bidimensionnels (GE2D), appellees skyrmions, dans le regime de l'effet Hall quantique a remplissage unitaire. On attend des excitations semblables appellees bimerons dans les systemes formes de deux GE2D couples. Contrairement au cas des GE2D simples, aucune experience n'a, a notre connaissance, presente la mesure d'une propriete specifique aux bimerons. Nous presentons dans cette these des travaux experimentaux ayant pour objectif l'etude d'excitations topologiques dans les heterostructures a double puits quantique. Une manifestation attendue (les bimerons est la presence d'une anisotropie dans la conductivite a travers une constriction. Nous avons concu un dispositif original a point de contact a trois grilles non-coplanaires. Ce dispositif a trois grilles a la particularite de permettre la creation d'une constriction etroite dans le double GE2D tout en permettant l'equilibrage de la densite electronique entre les deux puits dans l'etroit canal de conduction. Nous avons fabrique ce dispositif de taille submicronique par electrolithographie sur des heterostructures a double puits. Les dispositifs ainsi fabriques ont ete etudies a basse temperature (0.3K) et ont montre un fonctionnement conforme aux attentes. Les travaux n'ont pas permis de mettre en evidence une anisotropie de transport revelatrice de l'existence de bimerons. Cette these est a notre connaissance la premiere etude experimentale visant la realisation de l'experience d'anisotropie de transport et est ainsi une contribution significative a l'avancement des connaissances dans ce domaine. Les travaux theoriques que nous presentons ont permis de montrer l'effet des excitations topologiques sur la capacite grille-GE2D du systeme. Ces travaux ouvrent la voie de la detection des bimerons par l'intermediaire de la mesure de la capacite grille-GE2D ou encore de la susceptibilite electrique du

  4. Strontium and caesium transport in unsaturated soil from Chernobyl Pilot Site under steady flow conditions; Transfert de radioelements en zone non saturee. Etude experimentale et modelisation appliquees au Site Pilote de Tchernobyl

    Energy Technology Data Exchange (ETDEWEB)

    Szenknect, St

    2003-10-15

    This work is devoted to the quantification and the identification of the predominant processes involved in strontium and caesium transport in unsaturated soil from Chernobyl Pilot Site under steady flow conditions. The transport and fate of radionuclides in the subsurface is affected by various physical and chemical processes including advective and diffusive transport as well as chemical and biological transformations. Laboratory experiments and the use of a multiple tracer approach allow to isolate the contributions of each elementary process and to control the physico-chemical conditions in the system. To be more representative of the field conditions, we decided to perform column miscible displacement experiments. We perform batch and flow-through reactor experiments to characterize the radionuclides sorption mechanisms. Miscible displacement experiments within homogeneous columns and modeling allow to characterize the hydrodynamic properties of the soil and to describe the radionuclides behaviour under dynamic conditions at different water contents. We show that the water content of porous media affect the transport behaviour of inert and strongly sorbing radionuclides. Our results demonstrate that a parametrized transport model that was calibrated under completely saturated conditions was not able to describe the advective-dispersive transport of reactive solutes under unsaturated steady state conditions. Under our experimental conditions, there is no effect of a decrease of the mean water content on the sorption model parameters, but the transport parameters are modified. We established for the studied soil the relation between hydrodynamic dispersion and water content and the relation between pore water velocity and water content. (author)

  5. Experimental study of contamination by inhalation of radioactive iodine aerosols. Biological balance; Etude experimentale de la contamination par inhalation d'aerosols d'iode radioactif bilan biologique

    Energy Technology Data Exchange (ETDEWEB)

    Marble, G. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-07-01

    Several articles have been published concerning research into contamination produced by inhalation of radioactive iodine aerosols in monkeys. Results dealing with the biological balance of this contamination are presented and discussed in this report. (author) [French] L'etude experimentale de la contamination par inhalation d'aerosols d'iode radioactif effectuee chez le singe a fait l'objet de plusieurs publications. Les resultats concernant le bilan biologique de cette contamination sont presentes et discutes dans ce rapport. (auteur)

  6. Experimental study and mechanical modelling of the effects of water-driving in an oil saturated chalk. Application to the petroleum industry; Etude experimentale et modelisation mecanique des effets du balayage a l'eau dans une craie saturee d'huile. Application a l'industrie petroliere

    Energy Technology Data Exchange (ETDEWEB)

    Mata, C.

    2001-01-01

    The production of hydrocarbons may sometimes lead to compaction of the oil-reservoir layers with substantial collapse of the soil surface; this mechanism is usually mentioned as Subsidence. Classical remedy to this problem is to sustain the fluid pressure with the help of water injection. However, in presence of high porosity chalk (porosity > 30%), this technique does not give effective results: the subsidence rate at North Sea reservoirs (Ekofisk field), after injection, has remained unchanged. Some justify the subsistence in the chalk as caused by phenomena of dissolution of the carbonates; others think it is connected to the destruction of capillary menisci. In this research, we follow this second approach. This study is finalized to a better understanding of the compaction mechanisms in pure carbonates when water is injected. This is done by proposing -in micro-scale first and in macro-scale after- a physical model that agrees with empirical observations. In order to meet this target, IFP skills and experience in physical and chemical measurements (taken before, after and during mechanical tests) have proficiently joined ENPC laboratory (CERMMO) knowledge of micro and macro modelling. The soft rock studied is a Paris basin's white chalk (Craie de Guerville). Its physical and chemical characterisation (i.e.: silica content, porosity, permeability) is very similar to North Sea chalk, but Guerville chalk has never been in contact with oil and generally it crops out of the ground surface. Strength parameters of this rock have been first determined by standard triaxial tests. Three different saturation configurations have been examined: dry, fully oil-saturated and fully water-saturated. As literature clearly state, dry chalk is stronger than oil saturated chalk and the first two are largely stronger than water saturated chalk. Therefore uniaxial strain water injection tests have been performed on oil saturated samples. Results, coupled with previous physical measurements and SEM observation, let us highlight two different contributions to mechanical strength of chalk-: 1) The cohesion due to solid micro-bridges between calcite grains (always present in intact samples); 2) The cohesion due to water capillary menisci (which decreases when the degree of water saturation increases). On these grounds, an elasto-plastic model is proposed is order to explain how contributions are coupled. In this modelling, plastic strain is an hardening parameter while water saturation ratio is a softening one. Applications are developed in order to relate water-driving, stress state and subsidence rate in an oil reservoir configuration. (author)

  7. Etude experimentale des parametres biologiques de callosobruchus ...

    African Journals Online (AJOL)

    Coleoptere, Bruchidae) ont ete calcules sur la base de 24 tables de vie construites a partir de differentes combinaisons de facteurs liees a trois conditions thermo-hygrometriques, quatre substrats alimentaires et deux souches de C. maculatus. Il s'agit ...

  8. Contribution to the experimental survey of the nuclear isomerism. Application of the deferred coincidences method to research and to the survey of metastable states of short period; Contribution a l'etude experimentale de l'isomerie nucleaire. Application de la methode des coincidences differees a la recherche et a l'etude d'etats metastables de periode courte

    Energy Technology Data Exchange (ETDEWEB)

    Ballini, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1953-06-15

    transitions qu'ils subissent, lorsqu'elles donnent naissance a des especes nucleaires mieux connues: parmi ces transitions figurent les transitions isomeriques. Le but de ce travail est l'etude des transitions isomeriques a partir d'etats metastables de periode courte, comprise dans le domaine de la microseconde a quelques millisecondes. La methode des coincidences differees a ete mise au point et appliquee dans ce but en utilisant les avantages des selecteurs a plusieurs canaux, sous deux aspects principaux ou l'appareil a plusieurs canaux etait soit un selecteur de temps, soit un selecteur d'amplitudes. Cette methode a servi a etudier le fonctionnement de compteurs Geiger-Muller et a mesurer avec precision la periode de {sup 181}Ta{sup *} dans des conditions experimentales variees. La valeur adoptee est 17,2 {+-} 0,2 {mu}s. Ce travail a aussi trouve une application pratique immediate a la mise en evidence de quantites tres faibles de hafnium dans le zirconium, dont il constitue une impurete tenace et difficile a analyser par les moyens ordinaires. (M.B.)

  9. Modelos experimentales de anafilaxia

    OpenAIRE

    Yazmín Ravelo Calzado; Vivian Molina Cuevas; María de Lourdes Arruzazabala Valmaña; Daisy Carbajal Quintana

    2009-01-01

    Los modelos experimentales constituyen una herramienta clave en la búsqueda de nuevas opciones para el tratamiento y profilaxis de diversas condiciones patológicas. La anafilaxia, síndrome clínico con manifestaciones multisistémicas como urticaria, asma, vasodilatación sistémica, hipotensión y shock, entre otras, no resulta una excepción. El objetivo del presente trabajo consistió en presentar algunos de los modelos experimentales utilizados en la evaluación de sustancias con potenciales efec...

  10. COUPLAGE DES INDUCTANCES PAR RAYONNEMENT MAGNETIQUE. ETUDE THEORIQUE ET EXPERIMENTALE

    OpenAIRE

    Lorange, Jimmy

    2001-01-01

    This work is a first step towards the understanding of involuntary couplings of wound components. More specifically, it refers to inductors entering a 10 cm edge cube and working in the 100 kHz-10 MHz frequency range. Two topics are particularly developed: mathematical tools required to evaluate, in near field approximation, magnetic coupling of close components and metrology that suits the characterization of the induction radiated by such a component. Some characterizations of industrial co...

  11. Etude Experimentale du Photo-Injecteur de Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, Jean-Paul [Orsay

    2001-01-01

    TESLA (TeV Superconducting Linear Accelerator) is an international collaboration which is studying the feasibility of an $e^+e^-$ collider of energy 0.8 TeV in the center of mass. One of the first goals of this collaboration was to construct a prototype linear accelerator at the DESY Laboratory in Hamburg, the TESLA Test Facility (TTF), in order to establish the technical basis for the collider. Two injectors were developed for TTF: a thermionic injector (developed by LAL-Orsay, IPN-Orsay, and CEA-Saclay) and a photo-injector (developed by Fermilab). The thermionic injector was used from February 1997 to October 1998, and then it was replaced by the photo-injector, which was first operated in December 1998. Another photo-injector, identical to the one delivered to TTF, was installed at Fermilab in the $A{\\emptyset}$ Building. The first beam from the latter was produced on 3 March 1999. The photo-injector consists of an RF gun, followed by a superconducting cavity. The RF gun is a 1.625-cell copper cavity with a resonant frequency of 1.3 GHz. The gun contains a cesium telluride ($C_{s_2}$Te) photo-cathode, which is illuminated by UV pulses from a Nd:YLF laser. The system can produce trains of 800 bunches of photo-electrons of charge 8 nC per bunch with spacing between bunches of 1$\\mu$s and 10 Hz repetition rate. Upon emerging from the RF gun, the beam energy is 4 to 5 MeV; the beam is then rapidly accelerated by the superconducting cavity to an energy of 17 to 20 MeV. Finally, a magnetic chicane, consisting of 4 dipoles, produces longitudinal compression of the electron bunches. This thesis describes the installation of the photo-injector at Fermilab and presents the experimentally-measured characteristics of the injector. The principal measurements were quantum eciency, dark current, transverse emittance, and bunch length. The conclusion from these studies is that the quality of the photo-injector beam fullls the design goals. The photo-injector at Fermilab is presently available for user experiments, including the production of at beams and plasma wake eld acceleration.

  12. Etude du Photochromisme et de la Photorefractivite dans le Poly

    Science.gov (United States)

    Ghailane, Fatima

    1995-11-01

    Nous avons etudie la possibilite d'utiliser un materiau organique, le poly(vinylcarbazole) comme milieu de stockage optique de masse en temps reel. Ce materiau dope aux photochromes presente un potentiel non negligeable pour l'holographie de volume en temps reel. Plusiers cycles, Ecriture-Lecture-Effacement, ont ete enregistres dans cette matrice polymerique avec une resolution assez elevee. Une etude a ete menee afin d'obtenir la valeur des parametres comme l'epaisseur du film et l'intensite d'ecriture pour un angle d'enregistrement theta_{ acute ecriture} donne qui permettent d'obtenir les meilleures efficacites diffractionelles tout en preservant ce milieu de tout effet de fatigue ou de degradation. Ce polymere devient photorefractif une fois melange avec un bon accepteur de charge, le trinitrofluorenone et un bon chromophore non-lineaire, le disperse orange 25. Nous avons etudie experimentalement la conductivite en obscurite et la photoconductivite de ce materiau. Des simulations numeriques ont ete realisees en se basant sur le modele de Poole-Frenkel. Nous avons aussi etudie l'implantation de faisceaux d'ions d'oxygene d'energie 200 keV pour inscrire dans le PVCz un guide d'onde plan a profil d'indice. Une etude ESCA complete cette partie afin de savoir les modifications induites par implementation ionique a l'interieur du film polymerique.

  13. Numerical and experimental investigation of industrial electrostatic precipitators; Etude numerique et experimentale d`electrofiltres industriels

    Energy Technology Data Exchange (ETDEWEB)

    Tochon, P.

    1997-10-17

    This work deals with electrostatic precipitators or ESP used for gas-solid particles separation. By means of a dust-controlled testing loop created and realised at the GRETh`s plate-form (Research Group on Heat Exchangers) and a numerical model developed during this work from TRIO software, the study of the performances of different ESP geometries has been carried out. Many electrical, hydraulic and particular parameters governing solid particles collection under ionised electric field have been identified, measured and modelled. The numerical model, ratified with experimental data obtained during this study and from literature, allows to describe local and global phenomena occurring in any geometries. Furthermore, parametric studies have been carried out in order to propose some optimised geometries. allowing to increase collection efficiencies. At least, on-site measurements with CETIAT (Centre Technique des Industries Aerauliques et Thermiques) allow to identify dust particles likely to be thrown out to the atmosphere, and troubles peculiar to large scales industrial plants. The numerical model has also been tested on these data. At the end of this study, an efficient dust-controlled experimental tool, PACIFIC loop, and a numerical simulation allowing ESP sizing are available. (author)

  14. Experimental study of the Rapsodie protections; Etude experimentale des protections de rapsodie

    Energy Technology Data Exchange (ETDEWEB)

    Chapelet, M.; Edeline, J.; Lhiaubet, G. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-07-01

    This report gives details of the protection tests which have been carried out by the Protection Sub-Commission during the starting-up trials on the reactor Rapsodie. The main types of tests reported concern the flux measurements in the core, the reflectors, the sodium and the near biological protections, the radio-protection measurements in the premises, and the activation of the principal fluids. In the last part, the results obtained are analyzed and compared to the forecast calculations. (author) [French] Ce rapport rend compte des essais de protection qui ont ete effectues dans le cadre des essais de demarrage de RAPSODIE par la Sous Commission Protection. Les principaux types d'essais rapportes sont les mesures de flux dans le coeur, les reflecteurs, le sodium et les protections biologiques proches, les mesures de radioprotection dans les locaux, et l'activation des principaux fluides. Dans la derniere partie, les resultats obtenus sont analyses et compares aux calculs previsionnels. (auteur)

  15. Etude aerodynamique d'un jet turbulent impactant une paroi concave

    Science.gov (United States)

    LeBlanc, Benoit

    Etant donne la demande croissante de temperatures elevees dans des chambres de combustion de systemes de propulsions en aerospatiale (turbomoteurs, moteur a reaction, etc.), l'interet dans le refroidissement par jets impactant s'est vu croitre. Le refroidissement des aubes de turbine permet une augmentation de temperature de combustion, ce qui se traduit en une augmentation de l'efficacite de combustion et donc une meilleure economie de carburant. Le transfert de chaleur dans les au bages est influence par les aspects aerodynamiques du refroidissement a jet, particulierement dans le cas d'ecoulements turbulents. Un manque de comprehension de l'aerodynamique a l'interieur de ces espaces confinees peut mener a des changements de transfert thermique qui sont inattendus, ce qui augmente le risque de fluage. Il est donc d'interet pour l'industrie aerospatiale et l'academie de poursuivre la recherche dans l'aerodynamique des jets turbulents impactant les parois courbes. Les jets impactant les surfaces courbes ont deja fait l'objet de nombreuses etudes. Par contre des conditions oscillatoires observees en laboratoire se sont averees difficiles a reproduire en numerique, puisque les structures d'ecoulements impactants des parois concaves sont fortement dependantes de la turbulence et des effets instationnaires. Une etude experimentale fut realisee a l'institut PPRIME a l'Universite de Poitiers afin d'observer le phenomene d'oscillation dans le jet. Une serie d'essais ont verifie les conditions d'ecoulement laminaires et turbulentes, toutefois le cout des essais experimentaux a seulement permis d'avoir un apercu du phenomene global. Une deuxieme serie d'essais fut realisee numeriquement a l'Universite de Moncton avec l'outil OpenFOAM pour des conditions d'ecoulement laminaire et bidimensionnel. Cette etude a donc comme but de poursuivre l'enquete de l'aerodynamique oscillatoire des jets impactant des parois courbes, mais pour un regime d'ecoulement transitoire, turbulent

  16. Modelisation numerique et validation experimentale d'un systeme de protection contre le givre par elements piezoelectriques

    Science.gov (United States)

    Harvey, Derek

    Le degivrage au moyen d'actuateurs piezoelectriques est considere comme une avenue prometteuse pour le developpement de systemes a faible consommation d'energie applicables aux helicopteres legers. Ce type de systeme excite des frequences de resonances d'une structure pour produire des deformations suffisantes pour rompre l'adherence de la glace. Par contre, la conception de tel systeme demeure generalement mal comprise. Ce projet de maitrise etudie l'utilisation de methodes numeriques pour assister la conception des systemes de protection contre le givre a base d'elements piezoelectriques. La methodologie retenue pour ce projet a ete de modeliser differentes structures simples et de simuler l'excitation harmonique des frequences de resonance au moyen d'actuateurs piezoelectriques. Le calcul des frequences de resonances ainsi que la simulation de leur excitation a ensuite ete validee a l'aide de montages experimentaux. La procedure a ete realisee pour une poutre en porte-a-faux et pour une plaque plane a l'aide du logiciel de calcul par elements finis, Abaqus. De plus, le modele de la plaque plane a ete utilise afin de realiser une etude parametrique portant sur le positionnement des actuateurs, l'effet de la rigidite ainsi que de l'epaisseur de la plaque. Finalement, la plaque plane a ete degivree en chambre climatique. Des cas de degivrage ont ete simules numeriquement afin d'etudier la possibilite d'utiliser un critere base sur la deformation pour predire le succes du systeme. La validation experimentale a confirme la capacite du logiciel a calculer precisement a la fois les frequences et les modes de resonance d'une structure et a simuler leur excitation par des actuateurs piezoelectriques. L'etude revele que la definition de l'amortissement dans le modele numerique est essentiel pour l'obtention de resultats precis. Les resultats de l'etude parametrique ont demontre l'importance de minimiser l'epaisseur et la rigidite afin de reduire la valeur des frequences

  17. Etude experimentale et numerique de l’impact de la ventilation sur la qualite de l’air interieur

    OpenAIRE

    Limam, Kareem; Popescu, Olea; Abadie, M.; Savytskyi, Mykola; Iurchenko, I.; Ozhyshchenko, Olha

    2014-01-01

    Studies treating solid particles had received a restrained interest comparedwith other air pollutants, in spite of their direct effect on human health.People spend most of their time indoor that means they are in direct contactwith these pollutants for a long time. As deposition is one of the mostoften particle fate indoor it gives a good way to study indoor air quality.Experimental and numerical way of particle behaviour studies was chosen toevaluate IAQ in test chamber.

  18. An experimental study of mixed convection; Contribution a l'etude experimentale de la convection mixte

    Energy Technology Data Exchange (ETDEWEB)

    Saez, M.

    1998-10-20

    The aim of our study is to establish a reliable database for improving thermal hydraulic codes, in the field of turbulent flows with buoyancy forces. The flow considered is mixed convection in the Reynolds and Richardson number range: Re = 10{sup 3} to 6.10{sup 4} and Ri = 10{sup -4} to 1. Experiments are carried out in an upward turbulent flow between vertical parallel plates at different wall temperatures. Part 1 gives a detailed database of turbulent mixed flow of free and forced convection. Part 2 presents the installation and the calibration system intended for probes calibration. Part 3 describes the measurement technique (constant temperature probe and cold-wire probe) and the method for measuring the position of the hot-wire anemometer from the wall surface. The measurement accuracy is within 0.001 mm in the present system. Part 4 relates the development of a method for near wall measurements. This correction procedure for hot-wire anemometer close to wall has been derived on the basis of a two-dimensional numerical study. The method permits to obtain a quantitative correction of the wall influence on hot-wires and takes into account the velocity profile and the effects the wall material has on the heat loss. Part 5 presents the experimental data obtained in the channel in forced and mixed convection. Results obtained in the forced convection regime serve as a verification of the measurement technique close to the wall and give the conditions at the entrance of the test section. The effects of the buoyancy force on the mean velocity and temperature profiles are confirmed. The buoyancy strongly affects the fluid structure and deforms the distribution of mean velocity. The velocity profiles are asymmetric. The second section of part 5 gives an approach of analytical wall functions with buoyancy forces, on the basis of the experimental data obtained in the test section. (author)

  19. Experimental study of a water thermo-capillary loop; Etude experimentale d`une boucle thermocapillaire a eau

    Energy Technology Data Exchange (ETDEWEB)

    Lefriec, C.; Alexandre, A. [Ecole Nationale Superieure de Mecanique et d`Aerotechnique (ENSMA), 86 - Poitiers (France)

    1996-12-31

    This paper presents a bench scale experiment of a water thermo-capillary loop which allows to improve the understanding of its functioning mechanisms thanks to the internal visualisation of each component using transparent walls. The advantages of water are its non-toxicity, its high chemical compatibility with several materials and its low functioning pressure. The experimental device is presented and the functioning regimes of each component is analyzed: condenser (flow visualization, influence of tilt), evaporator (quality of heat exchange between teeth and porous medium, bubbles, heat exchange coefficient). (J.S.)

  20. Etude de la transmission sonore a travers un protecteur de type "coquilles" : modelisation numerique et validation experimentale

    Science.gov (United States)

    Boyer, Sylvain

    On estime que sur les 3,7 millions des travailleurs au Quebec, plus de 500 000 sont exposes quotidiennement a des niveaux de bruits pouvant causer des lesions de l'appareil auditif. Lorsqu'il n'est pas possible de diminuer le niveau de bruit environnant, en modifiant les sources de bruits, ou en limitant la propagation du son, le port de protecteurs auditifs individualises, telles que les coquilles, demeure l'ultime solution. Bien que vue comme une solution a court terme, elle est communement employee, du fait de son caractere peu dispendieux, de sa facilite d'implantation et de son adaptabilite a la plupart des operations en environnement bruyant. Cependant les protecteurs auditifs peuvent etre a la fois inadaptes aux travailleurs et a leur environnement et inconfortables ce qui limite leur temps de port, reduisant leur protection effective. Afin de palier a ces difficultes, un projet de recherche sur la protection auditive intitule : " Developpement d'outils et de methodes pour ameliorer et mieux evaluer la protection auditive individuelle des travailleur ", a ete mis sur pied en 2010, associant l'Ecole de technologie superieure (ETS) et l'Institut de recherche Robert-Sauve en sante et en securite du travail (IRSST). S'inscrivant dans ce programme de recherche, le present travail de doctorat s'interesse specifiquement a la protection auditive au moyen de protecteurs auditifs " passifs " de type coquille, dont l'usage presente trois problematiques specifiques presentees dans les paragraphes suivants. La premiere problematique specifique concerne l'inconfort cause par exemple par la pression statique induite par la force de serrage de l'arceau, qui peut reduire le temps de port recommande pour limiter l'exposition au bruit. Il convient alors de pouvoir donner a l'utilisateur un protecteur confortable, adapte a son environnement de travail et a son activite. La seconde problematique specifique est l'evaluation de la protection reelle apportee par le protecteur. La methode des seuils auditifs REAT (Real Ear Attenuation Threshold) aussi vu comme un "golden standard" est utilise pour quantifier la reduction du bruit mais surestime generalement la performance des protecteurs. Les techniques de mesure terrains, telles que la F-MIRE (Field Measurement in Real Ear) peuvent etre a l'avenir de meilleurs outils pour evaluer l'attenuation individuelle. Si ces techniques existent pour des bouchons d'oreilles, elles doivent etre adaptees et ameliorees pour le cas des coquilles, en determinant l'emplacement optimal des capteurs acoustiques et les facteurs de compensation individuels qui lient la mesure microphonique a la mesure qui aurait ete prise au tympan. La troisieme problematique specifique est l'optimisation de l'attenuation des coquilles pour les adapter a l'individu et a son environnement de travail. En effet, le design des coquilles est generalement base sur des concepts empiriques et des methodes essais/erreurs sur des prototypes. La piste des outils predictifs a ete tres peu etudiee jusqu'a present et meriterait d'etre approfondie. L'utilisation du prototypage virtuel, permettrait a la fois d'optimiser le design avant production, d'accelerer la phase de developpement produit et d'en reduire les couts. L'objectif general de cette these est de repondre a ces differentes problematiques par le developpement d'un modele de l'attenuation sonore d'un protecteur auditif de type coquille. A cause de la complexite de la geometrie de ces protecteurs, la methode principale de modelisation retenue a priori est la methode des elements finis (FEM). Pour atteindre cet objectif general, trois objectifs specifiques ont ete etablis et sont presentes dans les trois paragraphes suivants. (Abstract shortened by ProQuest.).

  1. Theoretical and Experimental Methods in Hypersonic Flows (Les Methodes Theoriques et Experimentales pour l’Etude Des Ecoulements Hypersoniques)

    Science.gov (United States)

    1993-04-01

    Electronic Fluorescence Dynamics, Grado /Italy, Vol. I1, 1986, pp. (RelieD Velocity Tagging of Oxygen. Exper- 565-574. Stuttgart: B.G. Teubner, 1986. iments...vibrationicl (fans des tuNZ~rcs tesi pri~sentee. Pour les conditions g~n~iatr-iccs consid~r~es, 1 onisation I es tenoes tie flux die Moude parfait son

  2. Experimental study of drop breakup in a turbulent flow; Etude experimentale de la rupture de gouttes dans un ecoulement turbulent

    Energy Technology Data Exchange (ETDEWEB)

    Galinat, S.

    2005-04-15

    This work presents the drop breakup phenomenon in a turbulent flow induced by a cross-section restriction in a pipe. A global analysis of single-drop breakup, in a finite volume downstream of the orifice, has allowed deriving statistical quantities such as the break-up probability and the daughter-drop distribution. These parameters are function of a global Weber number based on the maximal pressure drop through the orifice. At a local scale, the locations of breakup events are distributed heterogeneously and depend on the flow Reynolds number. The local hydrodynamic study in downstream of the orifice, which has been done by using Particle Image Velocimetry, reveals the specific breakup zones. Otherwise, this analysis has proved that the turbulence is the predominant external stress at the drop scale. The relation between drop deformation and the external stress along the trajectory has been simulated numerically by the response of a damped oscillator to the locally measured instantaneous turbulence forcing. The results of statistical analysis have allowed to introduce a breakup criterion, based on a unique deformation threshold value for all experiments. This multi-scale approach has been conducted to study drop breakup mechanisms in a concentrated dispersion. The breakup probability decrease with the increase of dispersed phase concentration, which influences the turbulent Weber number distribution in downstream of the orifice. (author)

  3. Etude des etats electroniques en champ magnetique dans le niveau de Landau N=0 de la tricouche ABC de graphene

    Science.gov (United States)

    Rondeau, Maxime

    Dans cet ouvrage nous etudions les phases du gaz d'electrons bidimensionnel dans la tricouche de graphene en empilement ABC. En partant du modele des liaisons fortes et en faisant l'approximation du continuum autour des vallees K +, K-, nous obtenons un modele effectif a deux bandes qui permet de decrire la physique de basse energie des electrons en champ magnetique dans cette structure. Ce modele contient trois orbitales degenerees dans le niveau de Landau N = O. Ce dernier est donc 12N φ, fois degeneres en incluant les degres de liberte de spin et de vallee. En ajoutant l'interaction de Coulomb au systeme et en considerant seulement les remplissages v = -5, -4, -4, 5 afin d'avoir un systeme a trois niveaux, nous etudions le diagramme de phase du gaz d'electrons en fonction d'un biais electrique entre les couches externes. Nous trouvons une phase d'onde de densite de charge bidimensionnelle (ODC2D) comme etat fondamental du systeme. Cette ODC2D se nomme cristal dans ce memoire et nous derivons ses proprietes de transports et ses modes collectifs. Nous discutons egalement du caractere topologique de ce cristal. Notre etude englobe aussi les phases liquides avec ou sans coherence orbitale. Nous concluons notre memoire par l'etude de quelques signatures experimentales des phases du gaz d'electrons dans la tricouche.

  4. Inmunogenicidad de la vacuna cubana recombinante heberbiovac HB en modelos experimentales y aplicados al humano

    National Research Council Canada - National Science Library

    González Ramírez, Victoria Esther; González Griego, Antonio; Ramírez Albajés, Victoria; Alerm González, Alina

    2000-01-01

    ... la utilización de la vacuna de producción cubana contra la hepatitis B. Se desarrollaron modelos experimentales y aplicados al humano que permitieron el estudio de inmunogenicidad mediante distintas...

  5. Conservation of an ion beam brightness. Study of a non brightness disturbing lens; Conservation de la brillance d'un faisceau ionique. Etude d'une lentille ne deteriorant pas cette brillance

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-11-01

    Experimental studies of ion sources prove that large initial brightnesses can be obtained by using the plasma expansion principle. However these brightnesses are usually spoiled by the beam focusing and accelerating systems. A high intensity focusing set up is first theoretically studied, then numerically determined by use of a 7094 IBM computer. Aberrations have been minimized. It has then been possible to construct a set up conserving the source initial brightness. For a 100 mA beam the focusing voltage is 150 kV, the beam study has been done for 350 keV beam final energy. Given is a discussion of results. (author) [French] L'etude experimentale des sources d'ions, montre que de grandes brillances initiales peuvent etre atteintes en utilisant le principe de l'expansion du plasma. Mais generalement ces brillances sont alterees par la focalisation et l'acceleration du faisceau. Nous presentions une etude theorique, suivie d'une determination numerique utilisant l'ordinateur IBM 7094, d'un montage capable de focaliser des intensites elevees. Nous nous efforcons de reduire au minimum les aberrations. Nous avons pu realiser un systeme conservant la brillance initiale de la source. Pour une intensite de 100 mA la tension de focalisation doit etre de 150 kV. L'etude du faisceau a ete faite a 350 keV. Nous discutons enfin des resultats obtenus. (auteur)

  6. Alecto 2 - interaction studies; Alecto 2 - etudes d'interaction

    Energy Technology Data Exchange (ETDEWEB)

    Brunet, J.P.; Clouet d' Orval, Ch.; Mougniot, J.C.; Penet, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    Weak interactions were experimentally studies with the tank of the critical assembly Alecto II and one, two or three bottles containing solutions of various concentrations. In particular, was studied the validity of certain classical assumptions, shielding effects, screening and semi-reflexion effects, importance of thermal coupling. The method of the 'k{sub eff}, solid angle' is shown to apply to such a system. The determination by divergence and pulsed neutron technique of the reactivity related to a millimeter of solution level affords the obtention of critical heights in terms of reactivity. (authors) [French] Une etude experimentale d'interactions faibles a ete faite entre la cuve de l'experience critique ALECTO II et une, deux ou trois bouteilles contenant des concentrations variees. On etudie, en particulier, la validite de certaines hypotheses classiques, effets d'ombre, d'ecrans, de semi-reflexion, importance du couplage thermique. On montre d'autre part que la methode du 'K{sub eff}, angle solide' peut s'appliquer a un tel systeme. La determination par divergence et neutrons pulses de la reactivite liee au millimetre de solution permet de traduire les hauteurs critiques obtenues, en terme de reactivite. (auteurs)

  7. ENFERMEDAD DE HUNTINGTON: MODELOS EXPERIMENTALES Y PERSPECTIVAS TERAPÉUTICAS

    Directory of Open Access Journals (Sweden)

    TERESA SERRANO SÁNCHEZ

    2011-01-01

    Full Text Available La enfermedad de Huntington (EH es un trastorno degenerativo de Weiss de origen hereditario. Hasta el momento no existe un tratamiento efectivo para la enfermedad que inexorablemente después de transcurridos 15 a 20 años, evoluciona hacia incapa- cidad total o muerte. En este trabajo se revisan las características clínicas y morfológicas de la EH y los modelos experimentales más utilizados para su estudio tomando como fuente, artículos indexados en la base de datos Medline publicados en los últimos 20 años. Se valoran las ventajas y desventajas de estos modelos y su perspectiva para el desarrollo de ensayos clínicos. El consenso de lo reportado plantea que de los modelos tóxicos, los inducidos por neurotoxinas tales como ácido quinolínico parecen ser los más adecuados para reproducir las características neuropatológicas, y por otro lado los modelos genéticos contribuyen con más evidencias al conocimiento del origen etiológico de la enfermedad. Numerosos tratamientos han sido aplicados en el manejo de las manifestaciones clínicas que aparecen en EH, sin poder detener o disminuir las afectaciones que derivan de la pérdida neuronal. La sintomatología clínica ha sido posible reproducirla, al menos en parte, en animales de experimentación lo que ha per- mitido realizar ensayos terapéuticos. Desde el punto de vista de tratamiento, lo que más promisorio parece ser, la terapia celular con células provenientes de diferentes fuentes y dentro de ellas las no neurales, que implican menor censura ética y mayor factibilidad de obtención para la aplicación en los enfermos. Por otro lado el desarrollo de la tecnología del ARN de interferencia, emerge como una herramienta terapéutica potencial para el tratamiento de EH, así como para responder interrogantes básicas relacionadas con el desarrollo de la enfermedad.

  8. Aplicación del Programa Microsoft Excel para resolver problemas experimentales de Física

    OpenAIRE

    Dania Cuenca Rodríguez; Ronal Tamayo Cuenca; Jorge Tamayo Pupo

    2010-01-01

    Se abordaron las principales aplicaciones de las hojas electrónicas de cálculo del programa Microsoft Excel para la solución de problemas experimentales de Física. Contiene los fundamentos teóricos y prácticos para su uso, con énfasis en el sistema de acciones e operaciones experimentales que pueden ser auxiliadas con la aplicación del Excel y se describe la experiencia de los autores en el desarrollo de las prácticas de laboratorio de Física en las carreras de ingeniería de la Universidad de...

  9. Sucesiones experimentales en pastizales con diferente uso y edad de abandono

    Directory of Open Access Journals (Sweden)

    Vargas Ríos Orlando

    2006-06-01

    Full Text Available Se presentan los resultados de la diversidad y cobertura de las especies vegetales presentes en parcelas después
    de generar disturbios experimentales (remoción epígea y remoción epígea-hipógea, en dos pastizales con diferente
    uso y edad de abandono, en la Reserva Forestal Municipal de Cogua, Cundinamarca (Colombia. Se observaron
    diferencias significativas entre los tratamientos y los pastizales en cuanto a diversidad y cobertura de las especies, dado el comportamiento diferencial de las especies a los disturbios experimentales realizados. En
    las parcelas con remoción epígea se obtuvo una regeneración rápida de la cobertura vegetal, con una composición de especies similar a la presentada antes de los disturbios experimentales. En los tratamientos con
    remoción epígea-hipógea la regeneración de la vegetación y el aumento de la cobertura es lento pero con un
    aumento en la diversidad con respecto a las especies presentes antes de los disturbios experimentales.

  10. El proceso enseñanza-aprendizaje de las Ciencias experimentales en una comunidad de aprendizaje

    OpenAIRE

    Ortega Quevedo, Vanessa

    2016-01-01

    La finalidad de este estudio es analizar el proceso de enseñanza-aprendizaje de las Ciencias Experimentales en una comunidad de aprendizaje. Para ello, se ha realizado una pequeña investigación sobre cómo profesores de un centro que ostenta el cargo de Comunidad de Aprendizaje trabajan las ciencias. Además, diseñan y llevan a la práctica una intervención que fusiona los modelos didácticos más usuales en la enseñanza de las Ciencias Experimentales, con la concepción comunicativa de la enseñanz...

  11. Las ciencias experimentales en Educación Infantil. "El huerto escolar".

    OpenAIRE

    García Cordovilla, Irene

    2016-01-01

    La finalidad de este trabajo es incorporar las ciencias experimentales en el aula de Educación Infantil de una manera amena teniendo en cuenta las inquietudes e intereses de los alumnos de esta etapa educativa. A través de la metodología por proyectos tenemos la oportunidad de desarrollar el pensamiento crítico de nuestros alumnos Grado en Educación Infantil

  12. Etude Par Spectroscopie Infrarouge des Oxydes Moleculaires Superoxyde de Potassium, Peroxyde de Potassium et Trioxyde de Silicium Isoles EN Matrice D'argon

    Science.gov (United States)

    Tremblay, Benoit

    1995-01-01

    A l'aide de la spectroscopie d'absorption infrarouge et de la technique d'isolation en matrice d'argon, nous avons repris l'etude des differents oxydes moleculaires qui se forment lorsque l'oxygene moleculaire se trouve dans des agregats avec du potassium, du silicium et de l'oxyde de silicium SiO. Le choix des oxydes moleculaires KO_2 et K_2O_2 a ete motive par le fait qu'ils ont souvent ete mis en evidence dans tres travaux en physique des surfaces lors de letude du systeme O_2/K/Si. Ces oxydes avaient deja ete identifies par spectroscopie infrarouge en matrice d'argon au debut des annees soixante-dix. Pour KO_2, l'observation des modes nu_2 et nu_3 pour de nombreuses especes isotopiques nous a permis de deduire la longueur de la liaison K-O et de l'angle O-K-O. En effet, la construction d'un champ de force harmonique nous a permis de determiner sa structure et des constantes de force qui reprodusient tres bien les frequences experimentales observees. L'etude de l'oxyde K_2O _2 s'est averee interessante car avant notre travail, seule une vibration avait ete mise en evidence. Nous avons reussi a observer deux nouvelles vibrations fondamentales: une bande infrarouge faible a 185 cm^{-1}, avec les isotopes ^{16}O _2, ^{18}O _2 et ^{16} O^{18}O de l'oxygene, et une autre, activee en infrarouge avec l'isotope ^{16}O^{18 }O a 405 cm^{-1}. Les donnees experimentales etant insuffisantes pour deduire la structure de la molecule, des calculs theoriques avec la methode de la fonctionnelle de la densite ont donne le structure et les vibrations non observees du K _2O_2. Ces donnees supplementaires sont venues completer les resultats experimentaux et nous ont permis de construire un champ de force harmonique avec bien les frequences observees. Les calculs theoriques ont monte que K_2O _2 doit etre de structure C_ {rm 2v}, bien que la structure D _{rm 2h} ne puisse pas etre rejetee, puisque qu'il y a un faible ecart entre les resultats des deux structures. Ensuite, nous avons

  13. Ciencias Experimentales en el aula de Educación Infantil

    OpenAIRE

    Zamalloa Echevarría, Teresa

    2013-01-01

    Duración (en horas): Más de 50 horas, Destinatario: Estudiante Mediante la metodología de ABP el alumnado de tercer curso del grado de Educación infantil elaborará propuestas didácticas en grupos para el estudio de los contenidos de ciencias experimentales empleando diferentes estrategias y recursos didácticos para la enseñanza/aprendizaje del medio físico y natural en Educación Infantil.

  14. Air quality monitoring: experimental study of in-station automatic calibration; Surveillance de la qualite de l`air: etude experimentale portant sur le calibrage automatique en station

    Energy Technology Data Exchange (ETDEWEB)

    Clauss, G.; Paillarguest, T.; Walenda, R.; Pesch, P.; Gerboles, M.; Payrissat, M. [Association pour la Surveillance et l`Etude de la Pollution Atmospherique en Alsace, Schiltigheim (France)

    1996-12-31

    The analysis of the polluting gases that are regulated by the European directive (SO{sub 2}, NO/NO{sub 2}, O{sub 3}) is done by automatic analyzers which are regularly calibrated in monitoring stations. The automatic calibration by means of stationary devices, regardless of whether they are integrated into the analyser or not, is only applied in 60% of the stations in the European Union because of the uncertainty about the choice of the device and the costs. For over a year an in-situ study has been undertaken with the aim of testing six automatic calibration devices in the stations of the French network ASSPA and of the German Network UMEG. These devices were different in the type of calibration standard (bottle low concentration, dilution, permeation, titration in gas phase), in the diluting and measuring devices of the flow rate and in the procedure for acquiring the data. The test took into account the degree of automation of the control calibration as well as the automatic correction of the calibration differences and the constraints of the site. The verification of the stability of the tested equipment was guaranteed by a quality assurance programme of ERLAP. The test results have been evaluated in relation to the calibration quality in terms of stability and reliability of the devices and in relation to the investment costs and the running of the station. Of all the tested calibration devices, the diluter-type combined with a ozone generator, which also offers the possibility to run a titration cycle in gas phase, could be the choice likely to satisfy the needs of the stations. The other systems, less complete, give relatively acceptable results where the use of ozone generators for calibration purposes is excluded.

  15. Experimental study and modelling of iron ore reduction by hydrogen; Etude experimentale et modelisation de la reduction du minerai de fer par l'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, D

    2008-01-15

    In an effort to find new ways to drastically reduce the CO{sub 2} emissions from the steel industry (ULCOS project), the reduction of iron ore by pure hydrogen in a shaft furnace was investigated. The work consisted of literature, experimental, and modelling studies. The chemical reaction and its kinetics were analysed on the basis of thermogravimetric experiments and physicochemical characterizations of partially reduced samples. A specific kinetic model was designed, which simulates the successive reactions, the different steps of mass transport, and possible iron sintering, at the particle scale. Finally, a 2-dimensional numerical model of a shaft furnace was developed. It depicts the variation of the solid and gas temperatures and compositions throughout the reactor. One original feature of the model is using the law of additive characteristic times for calculating the reaction rates. This allowed us to handle both the particle and the reactor scale, while keeping reasonable calculation time. From the simulation results, the influence of the process parameters was assessed. Optimal operating conditions were concluded, which reveal the efficiency of the hydrogen process. (author)

  16. Hydration of swelling clay and bacteria interaction. An experimental in situ reaction study; Hydratation des argiles gonflantes et influence des bacteries. Etude experimentale de reaction in situ

    Energy Technology Data Exchange (ETDEWEB)

    Berger, J

    2008-01-15

    This study reports on the physical-chemical behaviour of swelling di-octahedral clays (smectites) and their interaction with aqueous solutions and bacteria (Shewanella putrefaciens). Experimental results are presented for compacted clays, hydrated under confined volume conditions, using a new type of reaction-cell (the 'wet-cell' of Warr and Hoffman, 2004) that was designed for in situ X-ray diffraction (XRD) measurement. For comparison, dispersed clay systems were studied using standard batch solutions subjected to varying degrees of agitation. The combination of time-dependent in situ XRD measurements with gravimetric measurements and calculated diffraction patterns using the CALCMIX software (Plancon and Drits, 1999) allowed to successful quantification of the dynamics of water uptake and storage. This analytical procedure combined with published water vapour adsorption data enabled determination of the abundance of structured water layers, developed in the interlayer space, and the amount of water contained in different storage sites (interlayers, surfaces and pore spaces). Qualitative information on surface area and textural organization was also estimated based on calculated changes in the average particle thickness and the organization of water layer structures (ordering). Abiotic smectite hydration experiments, using a range of natural and industrial bentonites (SWy-2, IBECO, MX80, TIXOTON), focused on defining the role of the interlayer cation, variable clay packing densities and the ionic strength of the infiltrating solution. The rate of smectite hydration, as expected, was seen to be highly dependent on the type of interlayer cation (enhanced for Ca as opposed to Na) and the ionic strength of solution (enhanced uptake rates with saline solutions, particularly as they infiltrate Na-smectite). A range of dynamic changes in micro textural state occurred as a function of packing density. These changes explain the differences in hydration behaviour observed between Na- and Ca-smectite. The hydration mechanisms of compacted smectite occurring within a confined volume system are presented in a schematic model involving different scales, ranging from the Angstrom-scale of lattice layers to the bulk clay structure. Whereas the nature of interlayer cation affects hydration on all scales, the ionic strength of the infiltrating solution primarily affects the bulk texture. The impact of selected smectites (SWy-2, MX80 and nontronite) on the growth of S. putrefaciens was studied using agitated batch solution experiments combined with viable cell counts. The prolonged survival of bacteria in smectite suspensions compared to growth in culture medium is attributed to i) a continuous and sustainable supply of cationic nutrients and Corg, ii) the buffering capacity of the smectite clay and iii) the large clay surface areas, which accumulate nutrients, serve as attachment sites and sorb toxic waste products. The rate of bacterially induced smectite alteration/dissolution in batch solutions, as monitored by ICPOES and microscopy (confocal, ESEM and TEM coupled to EDX), shows depletion of the main cations in the nontronite extracted solution. This is attributed to the initial consumption and/or binding of cations by S. putrefaciens, which is probably related to the production of chelating agents. The constantly depleted Ca is most likely stored in the abundant EPS (exo-polymeric substance). Enhanced cation release in the case of nontronite in long-term experiments was especially evident for Fe and Al that corresponds to more than 10% partial dissolution. In contrast, the Fe-poor, Na-smectite was not seen to be affected by bacterial activity in this way and the increased release of Al by acid leaching corresponds to only 1.4% partial smectite dissolution. The presence of S. putrefaciens induced abundant textural changes as observed by microscopic investigations (confocal microscopy, ESEM), associated with the formation of smectite-aggregates and bio-films. In confined volume conditions, the presence of bacteria in Na-smectite clay was seen to enhance both the uptake of interlayer water and the amount of externally stored surface and pore water. In this type of compacted smectite, an increase in the total thickness of water layer structures occurs due to bacterial enhancement of sample porosity as seen by combined X-ray diffraction study and CALCMIX profile calculations. In the case of nontronite, additional water was stored as external water indicating a similar enhancement of porosity, but here, the rate of water inflow into the reaction cell decreased, most likely due to clogging of the pores by biofilm. With respect to the application of bentonites as a suitable backfill material in underground waste disposal sites, this study demonstrates that bacterial activity can modify both chemically and physically the properties of the smectite. Even if bacteria are not likely to survive in a hydrated bentonite seal, their effects are considered to be long-term, especially due to bacterially produced substances such as EPS and organic ligands. (author)

  17. Thermal design of horizontal tube boilers. Numerical and experimental investigation; Modelisation thermique de bouilleurs a tubes horizontaux. Etude numerique et validation experimentale

    Energy Technology Data Exchange (ETDEWEB)

    Roser, R.

    1999-11-26

    This work concerns the thermal design of kettle reboilers. Current methods are highly inaccurate, regarded to the correlations for external heat transfer coefficient at one tube scale, as well as to two-phase flow modelling at boiler scale. The aim of this work is to improve these thermal design methods. It contains an experimental investigation with typical operating conditions of such equipment: an hydrocarbon (n-pentane) with low mass flux. This investigation has lead to characterize the local flow pattern through void fraction measurements and, from this, to develop correlations for void fraction, pressure drop and heat transfer coefficient. The approach is original, since the developed correlations are based on the liquid velocity at minimum cross section area between tubes, as variable characterizing the hydrodynamic effects on pressure drop and heat transfer coefficient. These correlations are shown to give much better results than those suggested up to now in the literature, which are empirical transpositions from methods developed for inside tube flows. Furthermore, the numerical code MC3D has been applied using the correlations developed in this work, leading to a modeling of the two-phase flow in the boiler, which is a significant progress compared to current simplified methods. (author)

  18. Contribution to the experimental study of the polarized liquid helium-3; Contributions a l'etude experimentale de l'helium-3 liquide polarise

    Energy Technology Data Exchange (ETDEWEB)

    Villard, B

    1999-07-15

    Spin-polarized liquid helium-3 is prepared by laser optical pumping in low magnetic field and at room temperature, prior to fast liquefaction of the polarized sample. The use of a new helium-3 cryostat enabled us to obtain liquid helium-3 with polarization rates up to 25 % at well-stabilized temperatures (around 0.5 K). We could thereby study the effect of nuclear polarization on liquid-vapour equilibrium, and particularly on the saturated vapour pressure. Very sensitive capacitive gauges were developed. We estimated (to first order in M{sup 2}) the expected effects when the polarization M is suddenly destroyed. These effects were experimentally observed in helium-3/helium-4 mixtures, in pure helium-3, only a transient increase in pressure has been recorded. We then describe in a third part a preliminary experiment which aimed at determining the longitudinal relaxation time T1 in mixtures. Relaxation on the walls is efficiently reduced by a cesium coating and T1s of order 20 minutes were observed. A careful determination of the helium-3 concentration in the liquid phase was made. Finally we studied the effects of dipolar field on transverse polarisation decay in our strongly polarized samples. We observed the free precession of polarization after a NMR pulse, and analysed in detail its decay time constant as a function of different parameters. This time constant drastically varied with the tipping angle, an effect which could be linked to NMR dynamical instabilities. (author)

  19. Adsorption of trace elements on a bentonite sample: experimental study and modelling; Retention d'elements trace sur une bentonite: etude experimentale et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Hurel, Ch

    2002-12-15

    Radioactive waste storage in deep underground is studied in France. The alteration of the radioactive waste can mobilize the elements that can migrate to the geosphere. Clays (bentonite) are investigated as major materials constituting the barriers because of their low permeability and high retention capacity. A thermodynamic surface complexation model, based on the component additivity principle was investigated, in order to predict the adsorption behaviour of pollutants in contact with clay. This principle allows an independent determination of each parameter of the model, limiting the fitting procedure of correlated data, and it allows the use of an adsorption thermodynamic database for a solid. The predictions obtained were in good accordance with experimental data. The model could then be applied successfully in performance assessment. (author)

  20. An experimental study of electrical and dielectric properties of consolidated clayey materials; Etude experimentale des proprietes electriques et dielectriques des materiaux argileux consolides

    Energy Technology Data Exchange (ETDEWEB)

    Comparon, L

    2005-06-15

    This study is devoted to the electrical and dielectric properties of consolidated clays. A better understanding of the conduction and polarization phenomena in clays is necessary to better interpret in situ measurements in terms of water saturation and texture. An experimental study was carried out on synthetic clay samples (kaolinite and smectite) compacted with various water contents, porosities and mineralogical compositions, on a large frequency range, using three laboratory setups. The electrical properties of natural argillites (from ANDRA) were then investigated. We found that the response of the synthetic samples is mainly controlled by water content on the whole frequency range; two polarization phenomena were observed, which were related to the Maxwell-Wagner polarization and the electrical double layer polarization around the clay particles. The electrical response of argillites is more complex; it is controlled by water content but also by the microstructure of the rock. In these rocks, the electrical and dielectric anisotropies are high; anisotropy was also measured for the synthetic clays. The existing models explain the high frequency limit of the dielectric permittivity of the clayey materials, but the low frequency part of the spectra ({<=}1 MHz) needs theoretical developments. (author)

  1. Experimental and numerical study of the active control of jets inside combustion chambers; Etude experimentale et numerique du controle actif de jets dans des chambres de combustion

    Energy Technology Data Exchange (ETDEWEB)

    Faivre, V.

    2003-12-15

    Combustion instabilities occur when the flame heat release couples with the acoustic waves propagating in the combustion chamber. This phenomenon can lead to strong vibrations and noise but also, sometimes, to the complete combustion device failure. That is the reason why so many studies focus on the control of those instabilities. The method chosen in this study consists in an active control device (or set of actuators) having a strong effect on the mixing of the burner exhaust flow with the ambient fluid. The model configuration studied consists in a non reactive jet of air controlled by four small tangential secondary jets. Experiments have been carried out to optimize the control device geometry. The configuration identified as the most efficient, in terms of mixing enhancement, has been simulated through Large Eddy Simulations (LES). The objective of the numerical part of the present work is double. First, the numerical simulations provide a better understanding of the phenomena occurring when the control is on. Then, it is shown that LES can be considered as a tool to predict the effects of a control device on a flow. (author)

  2. Theoretical and experimental study of cyclotronic waves in a fusion plasma; Etude theorique et experimentale des ondes cyclotroniques electroniques dans un plasma de fusion

    Energy Technology Data Exchange (ETDEWEB)

    Vezard, D.

    1994-12-20

    This thesis presents a study concerning cyclotronic waves in a plasma. It starts with an illustration of the elementary interaction between electromagnetic waves and matter.It shows that electrons from tokamak absorbs waves at cyclotronic frequency. Cyclotronic waves are studied by solving the dispersion relation in plasma; it concerns polarisation, absorption, dispersion, extinction. Then, classical theories are reminded in order to speak about decoupled electrons and their interactions. Absorption and emission properties of cyclotronic waves by electrons from a queue are described. After that, cyclotronic waves propagation is studied taking into account resonance. The last part of this thesis is dedicated to the electronic distribution function that is made by a wave spectra at a inferior hybrid frequency. (TEC). 129 refs., 75 figs.

  3. The transition radiation. 2. experimental study of the optical transition radiation; Le rayonnement de transition: 2. etude experimentale du rayonnement de transition optique

    Energy Technology Data Exchange (ETDEWEB)

    Couillaud, Ch.; Haouat, G.; Seguin, S.; Striby, S

    1999-07-01

    Optical-transition-radiation-based diagnostics have been widely used for many years on electron accelerators in order to measure beam energy and transverse and longitudinal emittances. These diagnostics are very attractive for high brightness electron beams used as drivers for radiation sources. Such diagnostics have been performed on the ELSA facility (18 MeV electron energy, 100 A peak current) using both a single interface and an OTR-Wartski interferometer. We present the accelerator, the experimental set-up and the method for analyzing the OTR angular distribution. Then, the experimental results are described and compared with those from the three gradient method. In addition, we present a beam energy measurement using OTR interferogram analysis. (author)

  4. Mechanics of Composite Materials. Summary of Some Theoretical and Experimental Studies (Mechanique des Materiaux Composites. Apercus de Quelques Etudes Theoriques et Experimentales),

    Science.gov (United States)

    1980-06-01

    multilayer composite materials. Assessment calculation by limit analysis. ( Comportement plastique des mat~riaux composites multicouches. Calculs de...0 LGG E QUANTIQUE (ror ag atoa (Dvnamnque des mft(e. stratifies) rbseaux) PHYSIQUE DES M9TAUX MECANIQUE %at~riaux nouveauxl (Miieux cOntinus

  5. ETUDE STRUCTURALE CRISTALLINE EXPERIMENTALE A PARTIR DE LA DIFFRACTION X ET THEORIQUE (DFT DE L’IODODURENE (C10H13I

    Directory of Open Access Journals (Sweden)

    A.N HAMDOUNI

    2015-06-01

    Full Text Available Dans cette étude nous présentons d’une part la structure cristalline du 1-iodo-2,3,5,6-tétraméthylebenzène (C10H13I aussi connu comme iododurène à partir de la diffraction des rayons X à température ambiante et d’autre part la conformation moléculaire de ce même composé à partir des calculs de la théorie de la fonctionnelle de la densité (DFT. Ce composé cristallise dans le système orthorhombique, groupe spatial P212121 et Z=4. L’empilement moléculaire se fait suivant le plus court axe cristallographique a. Les résultats de calcul de la mécanique quantique en utilisant la chaîne de programme Gaussian03 (DFT avec deux fonctionnelles B3LYP et MPW1PW91 et le jeu de base DGDZVP ont conduit à deux conformations différences  de symétrie C2v et Cs avec des énergies de formation minimales voisines. En prenant en compte les résultats de calcul de la fonctionnelle MPW1PW91/DGDZVP comparés à l'expérience on trouve que les écarts sont compris entre  ± 0.103° pour les angles de liaison  et ± 0.001 Å  pour les longueurs de liaison. Le programme permet également d’obtenir en  plus  du calcul d’optimisation de prédire les modes normaux de vibrations internes de l’iododurène. Ainsi, l’attribution des modes donne un très bon accord entre les fréquences calculées et observées.

  6. Multi scale experimental study of water and ionic transport in porous charged media: clays; Etude experimentale multiechelle du transport ionique et aqueux en milieu poreux charge: argiles

    Energy Technology Data Exchange (ETDEWEB)

    Cadene, A

    2005-10-15

    Clays are porous media of industrial interest. Due to their retention capacities and low permeability to water, they are the principal candidate for the conception of engineered barriers radioactive waste disposal. The main interest of this study is the experimental determination of the cationic and water dynamics in montmorillonite and fluoro-hectorite at low water contents This latter synthetic smectite has been used as a model clay to help the interpretation of the results issued from the first natural one. After a summary on the clayey system, this work reports the many experimental techniques (Atomic Force Microscopy, Photo-Correlation Spectroscopy, Micro-calorimetry, Powder Diffraction) used during the preliminary study concerning structural characterisation of the samples. The study of the sodic form of smectites with the use of a combination of quasi-elastic neutron scattering techniques (Time of Flight and Spin Echo) succeeded to water diffusion coefficients but also to a discernment of the limits of such techniques. Experiments with montmorillonite samples are in agreement with the simulations, so tending to a validation of the models. Experimental data obtained from synthetic hectorites will be in the near future compared to simulations In the last part, this work shows the application of Broad Band Dielectric Spectroscopy for the investigation of ionic dynamic in these porous media. Many models have been developed for the interpretation of the experimental raw data obtained with this technique. (author)

  7. Experimental and theoretical study of phase transitions under ball milling; Etude experimentale et modelisation des changements de phases sous broyage a haute energie

    Energy Technology Data Exchange (ETDEWEB)

    Pochet, P

    1997-12-31

    The aim of this work was to determine how phase transition s under ball-milling depend on the milling conditions and to find out if one can rationalize such transitions with the theory of driven alloys. We have chosen two phase transitions: the order-disorder transition in Fe Al and the precipitation-dissolution NiGe. In the case of Fe Al we have found that the steady-state long range order parameter achieved under ball milling intensity; moreover the same degree of order is achieved starting from an ordered alloy or a disordered solid solution. On the way to fully disordered state the degree of order either decreases monotonically or goes through a short lived transient state. This behaviour is reminiscent of a first order transition while the equilibrium transition is second order. All the above features are well reproduced by a simple model of driven alloys, which was originally build for alloys under irradiation. The stationary degree of order results of two competitive atomic jump mechanisms: the forced displacements induced by the shearing of the grains, and the thermally activated jumps caused by vacancies migrations. Finally we have performed atomistic simulations with a Monte Carlo kinetic algorithm, which revealed the role of the fluctuations in the intensity of the forcing. Moreover we have shown that specific atomistic mechanisms are active in a dilute NiGe solid solution which might lead to ball milling induced precipitation in under-saturated solid solution. (author). 149 refs.

  8. Experimental study of the topological aspect of the ergodic divertor in Tore-supra tokamak; Etude experimentale des aspects topologiques du divertor ergodique de Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Costanzo, L

    2001-10-01

    The control of power deposition onto plasma facing components in tokamaks is a determining factor for future thermonuclear fusion reactors. Plasma surface interaction can be performed using limiters or divertors. The ergodic divertor installed on Tore Supra is an atypical example of a magnetic divertor. It consists in applying a magnetic perturbation which establishes a particular topology of the plasma in contact with the wall (edge plasma). We carried out dedicated experiments in order to study parallel heat flux which strike the divertor neutralizers. This quantitative and qualitative analysis of heat flux as a function of experimental conditions allows to determine the profiles of power deposition along the neutralizers. The influence of plasma electron density, additional heating, impurities and injected gas was established. An experimental study of the sheath heat transmission factor {gamma} was carried out by correlating measurements made with Langmuir probes and infrared imaging. This study gave rise to a major conclusion: for ohmic discharges with deuterium injection and most of the time with helium, it was experimentally confirmed that {gamma}=7 in agreement with classical sheath theory. However, an increase of this factor with additional power has been shown. Detached plasma, which is an attractive regime in order to reduce the power deposition, requires an optimized control. A new measurement of the detachment onset has been developed. It is based on the variation of heat flux onto the plates derived from infrared measurements. A detachment cartography with the determination of a new 2D 'IR' Degree of Detachment was carried out allowing to locate the zone where the detachment starts. We can apply this concept both to other tokamaks such as JET and ITER. A comparison between the axisymmetric divertor and the ergodic divertor is also presented concerning the power deposition in the two configurations. Low heat flux with the ergodic divertor is a major advantage. (author)

  9. Lanthanides in geological fluids: experimental study of standard thermodynamic properties and of solubilities; Les lanthanides dans les fluides geologiques: etude experimentale des proprietes thermodynamiques standard et des solubilites

    Energy Technology Data Exchange (ETDEWEB)

    Pourtier, E

    2006-11-15

    Standard thermodynamic properties (STP) of lanthanides (Ln{sup 3+}) are necessary to predict their transport in hydrothermal fluids. New STP (apparent molal volumes and heat capacities) of Ln{sup 3+} are determined with dilute (La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Yb{sup 3+}) triflates solutions, up to 300 deg. C and 300 bars, using a vibrating tube flow densimeter and a differential heat flow calorimeter. The triflate anion (CF{sub 3}SO{sub 3}), stable at high temperature, does not form complexes with Ln{sup 3+}. The STP of HCF{sub 3}SO{sub 3} and NaCF{sub 3}SO{sub 3} are measured in order to get the STP of CF{sub 3}SO{sub 3}. The solubility of the Nd-pure pole of monazite (NdPO{sub 4}) studied between 300 and 800 deg. C at 2 kbars in H{sub 2}O and H{sub 2}O+NaCl using weight loss and isotope dilution methods, is prograde for neutral pH. The study of Nd{sup 3+} speciation at 650 deg. C and 300 deg. C, 2 kbars, shows that only hydroxylated species are present. These data allow the revision of Ln{sup 3+} parameters in the HKF model. (author)

  10. Experimental study of heat and mass transfer across a density interface; Etude experimentale des transferts de chaleur et de masse a travers une interface de densite

    Energy Technology Data Exchange (ETDEWEB)

    Zellouf, Y.

    2004-11-15

    This work is part of a major research program on stratified flows encountered in the storage tanks of liquid natural gas. The subject of this dissertation concerns more particularly the problem of heat and mass transfer across a density interface. These flows are complex by nature due to the combination of three parameters: density difference {delta}{rho} across the interface, turbulence intensity u' in the homogeneous layers and the diffusivity K of the stratifying components. To control the operational conditions of the liquid gas storage, it is crucial to have a universal physical model to estimate the fluxes across the interface and to predict the brutal mixing of homogeneous layers commonly called the 'roll-over' event. In this work heat and mass transfer across an interface is measured in the presence of turbulence generated by vertical oscillation of two grids. Turbulent velocity field is measured in a homogeneous environment by Particle Image velocimetry (PIV). It shows that the turbulence generated by the two grids is homogeneous and isotropic in the vertical plan. We have established, based on this measurements, an experimental decay law of the turbulence intensity as a function of the flow parameters and the distance from the grids. Stratifications have been followed in time by recording the vertical profiles of temperature and density. Measured heat and mass fluxes are presented as a function of the three flow parameters (u', {delta}{rho}, K) through the non-dimensional numbers: Richardson number Ri g({delta}{rho}/{rho}{sub 0})(l'/u'{sup 2}) and Peclet number Pe = u'l'/K. Measurements show that these two parameters have opposite effects on transfer phenomena. While thermal diffusivity favours the entrainment near the interface, the stratification effect limits this entrainment. This fact is explained by analysing the interface structure. A phenomenological model is then proposed which takes into account these parameters. (author)

  11. Experimental and theoretical study of the atmospheric boundary layer over the paris area; Etude experimentale et theorique de la couche limite atmospherique en agglomeration parisienne

    Energy Technology Data Exchange (ETDEWEB)

    Menut, L

    1997-12-15

    This thesis studied the urban boundary layer dynamic behaviour over the Paris area by comparing urban (Paris) and suburban (Palaiseau) dynamic data such as lidars, sodars, sonic anemometers. All the data were obtained during the ECLAP experiment, specifically performed to characterize the differences between a city and its near environment. (author)

  12. Etude de la transmission sonore par voie externe d'un bouchon d'oreille couple au conduit auditif: Modelisation numerique et validation experimentale

    Science.gov (United States)

    Viallet, Guilhem

    The objective of this thesis is to contribute to the better understanding of the problem of the sound transmission through the earplug-earcanal system to improve the design of the protector, to contribute to a better assessment of its effectiveness and thus ultimately to improve the worker's protection. This objective is accomplished via a methodological development of a predicting tool to simulate the attenuation in the framework of a step by step modeling approach which integrates gradually geometrical and physical complexities. In the first step, only the geometrical aspect of the ear canal is studied via the question of the validity of a simplified 2D axisymmetric description of the ear canal geometry in the case of rigid boundary conditions. This choice of boundary conditions allows in a first approximation to set aside the problems associated with the integration of the earcanal constitutive tissues. This question is investigated through comparisons of attenuation predictions with 2D and 3D models, and for individual or averaged over a group cases. The emphasis is put on finding the most reliable 2D geometry reconstruction method (in terms of attenuation prediction) which can be used, in order to define a 2D axisymmetric geometry based on geometrical characteristics of a 3D one. In the second step, the previous 2D model is extended to take into account a layer of skin on the ear canal walls. This also corresponds to a configuration of the synthetic earcanal included in the acoustical test fixtures that are commonly used to measure the attenuation. The role of the skin and its effect on the earplug attenuation are studied. The contributions of the different acoustic pathways due to an airborne excitation are quantified. More generally, the investigation concerns the energy circulating within the domain. In addition, statistical analyses were performed to quantify the effect on the attenuation of the mechanical parameters of both the skin and the earplug. In the third step, the previous model is extended to take into account the others tissues surrounding the ear canal (bone and soft tissues). Moreover, the previous geometry (the cylindrical one) is partially modified to obtain an average 2D axisymmetric ear canal geometry with a variable cross section. This model is first validated by comparisons with measurements on human subjects and then exploited to quantify the impact of various factors known to vary the attenuation when measured in laboratory conditions. These factors are: the possible presence of leaks, the insertion depth of the earplug, the inter-individual variation of the ear canal geometry and the variation of the mechanical parameters associated with the surrounding tissues. These factors are introduced one by one in the model and their impact on the attenuation is quantified and thereafter compared to standard deviations obtained from attenuation measurements on human subjects. Such comparisons are used to evaluate the predominance (as a function of the frequency) of the aforementioned factor effects on the attenuation. In the fourth step, the study goes into the possibility of replacing the surrounding tissues of the ear canal by mechanical impedance boundary conditions. This work ultimately aims to simplify the models developed in the third step, by using models of steps 1 and 2 improved by the mechanical impedance boundary conditions rather than the more conventional condition limits (the fixed one) used till now. Two tissue replacement scenarios have been tested in the 2D axisymmetric configuration described in the first approximation. In the first scenario (similar to step 1), the effect of all the tissues (skin, soft tissue and bone) were reduced to a mechanical impedance. A second scenario, a little less simplified, where only the bone and soft tissue domains are replaced is then considered. This second scenario allowed to correct the limitations obtained in the first scenario and helped to achieve more realism in terms of attenuation predictions, closer than those obtained with the model developed in step 3. These tests were performed on a unique geometry that does not allow generalizing the method validation which could be extended in future works to 3D models or 2D axisymmetric models with variable cross sections. From a scientific point of view, each of the steps described above helped to better understand the key mechanisms involved in the attenuation of an earplug, the pathways leading the acoustic transmission in the case of an airborne sound excitation through the occluded ear canal, and to investigate the possible simplification which can be done to predict a realistic attenuation with a numerical model. From a technological point of view, the sensitivity analyses performed on the earplug mechanical parameters with the modeling tools developed in this thesis provide concrete ways for the manufacturers to improve their product effectiveness. (Abstract shortened by UMI.).

  13. Experimental study of turbulence on Tore Supra by plasma micro-waves interaction; Etude experimentale de la turbulence sur Tore Supra par interaction plasma micro-ondes

    Energy Technology Data Exchange (ETDEWEB)

    Colas, L

    1996-09-23

    Internal small-scale magnetic turbulence is a serious candidate to explain the anomalous heat transport in tokamaks. This turbulence is badly known in the gradient region of large machines. In this work internal magnetic fluctuations are measured on Tore Supra with an original diagnostic : Cross Polarization Scattering (CPS). This experimental tool relies on the Eigenmode change of a probing polarised microwave beam scattered by magnetic fluctuations, close to a cut-off layer for the incident wave. In this work, the diagnostic is first qualified to assess its sensitivity to magnetic fluctuations, and the spatial localisation for its measurements. The magnetic fluctuation behaviour is then analysed over a wide range of plasma current, density and additional power, and interpreted with a simple 1-D scattering model. A scan of the plasma density or magnetic field is used to move the CPS measurement location from r/a = 0.3 to r/a = 0.75. A fluctuation radial profile is obtained by two means. In L-mode discharges, the relation between magnetic fluctuations, temperature profiles and local heat diffusivities is investigated. With all measurements, it is also possible to look for a local parameter correlated to the turbulence in a large domain of plasma conditions. The fluctuation-induced local heat diffusivity expected from the measured fluctuations is estimated using the non-collisional quasi-linear formula: X{sup mag}{sub e} = {pi}qRV{sub te}({delta}B / B){sup 2}. Both the absolute values and the parametric dependence of calculated X{sup mag}{sub e} are close to the electron thermal diffusivities Xe determined by transport analysis. In particular, a threshold is evidenced in the dependence of fluctuation-induced heat fluxes on local {nabla}T{sub e}, which is analogous to the critical gradient for measured heat fluxes. The experimental setup is also sensitive to the Thomson scattering of the probing wave by density fluctuations. Its measurements are analysed as the fluctuations of the amplitude and the phase of an interferometer, thanks to a simple modelling of the plasma poloidal motion. Thus one than measure from the spectra shapes statistical quantities of the plasma movement. (author)

  14. INFLUENCIA DE DIFERENTES VARIABLES EXPERIMENTALES EN LA COMPOSICIÓN DEL COMPLEJO DE BIOFLAVONOIDES DEL LIMÓN (CBL)

    OpenAIRE

    O. Cartaya; Inés Reynaldo; Clara Nogueiras

    2002-01-01

    En este trabajo se estudió la influencia de las variables experimentales: proporción (m/v) residuo/agua, la temperatura y el tiempo de extracción en el rendimiento y la composición del CBL a través de un diseño experimental factorial 23. Para cada experiencia se evaluó el rendimiento, el contenido de azúcares totales y reductores, la concentración de flavonoides totales y la acidez total, evidenciándose la relación que existe entre las variables evaluadas y las condiciones experimentales sele...

  15. Use of hydraulic and aerial mock up to study atmospheric pollution; L'utilisation des maquettes aeriennes et hydrauliques pour l'etude de la pollution atmospherique

    Energy Technology Data Exchange (ETDEWEB)

    Facy, L.; Perrin De Brichambaut, C.; Doury, A.; Le Quinio, R

    1962-07-01

    Fundamental studies on turbulent atmospheric diffusion of finely divided particles, cannot remain on a purely theoretical basis. Further experimental studies must be considered. - In full scale, from accidental and induced releases. - On a reduced scale, in aerodynamic wind tunnels or hydraulic water tunnels. A first set of studies on reduced scale models has been worked out according to a contract between French 'Meteorologie Nationale' and French 'Commissariat a l'Energie Atomique' and with the Collaboration of Saint-Cyr 'Institut Aerotechnique'. Essentially two kinds of results have been obtained: - The mathematical model of SUTTON for the turbulent diffusion in the atmosphere, deduced from the SUTTON theory, generally used by us, has been correctly verified, qualitatively and quantitatively whenever experiments were consistent with the theory conditions. - The quantitative assays of photographic and cinematographic visualization have given precise details on the phenomena inaccessible to calculations, due to the influence of obstacles and release conditions. - Generally, it can be asserted, that the atmospheric pollution studies are worked out by mock up experimentations and that, in some cases these experiments never can be replaced by mathematically pure models. (authors) [French] Les etudes fondamentales portant sur la diffusion turbulente dans l'atmosphere de quantites de matieres finement divisees, ne peuvent se maintenir sur un plan exclusivement theorique. C'est pourquoi des etudes experimentales complementaires doivent etre obligatoirement envisagees: - en vraie grandeur, a partir d'emissions accidentelles ou provoquees; - sur modeles reduits, en soufflerie aerodynamique ou en veine hydraulique. En ce qui concerne les modeles reduits, une premiere serie d'etudes a pu etre menee a bien, dans le cadre d'un contrat passe entre la Meteorologie Nationale et le Commissariat a l'Energie Atomique

  16. Aerodynamic study of the fluid flow in the channel of a reactor filled with internally and externally cooled fuel elements; Etude aerodynamique de l'ecoulement fluide dans un canal de reacteur charge en elements combustibles annulaires refroidis interieurement et exterieurement

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, J.C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    A study is made of the problem of the flow-rate and pressure distributions along the length of two volumes, internal and external, bounded by a series of non-continuous annular elements placed along the channel axis. It is observed that the phenomenon can easily be represented by equations. The theoretical expressions observed are particularly simple when the distances between the elements are above a certain minimum value. The experimental work has made it possible to show that the theoretical formulation derived is valid with a very great accuracy. The experimental study has also been carried out in the case of a very small spacing between the elements. It has been possible to show in this case that the hypothesis made for deriving the theoretical expressions was perfectly justified. In the last part finally, we consider the practical problem of evaluating the pressure-drops between the ends of a series of annular elements. (author) [French] On etudie le probleme de la repartition des debits et des pressions le long des deux espaces, interne et externe, delimites par une succession d'elements annulaires non jointifs, disposes suivant l'axe d'un canal. On constate que le phenomene peut etre mis aisement en equation. Les relations theoriques obtenues prennent en particulier une forme simple lorsque les intervalles entre elements sont superieurs a une valeur minimum. L'etude experimentale a permis de constater que cette formulation theorique etablie etait alors valable avec une precision excellente. L'etude experimentale a ete egalement effectuee dans le cas de tres faibles intervalles entre elements consecutifs. On a pu alors verifier que l'hypothese adoptee dans l'etablissement des relations theoriques etait parfaitement justifiee. Dans un dernier chapitre enfin, nous abordons le point de vue pratique de l'evaluation des pertes de charge aux bornes d'un train d'elements annulaires. (auteur)

  17. Evaluación del efecto de dietas artificiales experimentales en el rendimiento reproductivo de penaeus vannamei

    OpenAIRE

    Espín, Marcos

    2000-01-01

    Evaluación del Efecto de Dietas Artificiales Experimentales en el Rendimiento Reproductivo de Penaeus vannamei Dos ensayos nutricionales a escala comercial fueron realizados para comprobar el efecto de la utilización de dietas artificiales y la sustitución parcial de los alimentos frescos en el rendimiento reproductivo de Penaeus vannamei.

  18. PENULISAN ETUDE-ETUDE MUSIK TALEMPONG UNGGAN (Sebuah Usaha Pembelajaran Musik Tradisi Berbasis Literatur

    Directory of Open Access Journals (Sweden)

    Asri MK

    2014-12-01

    Full Text Available “Talempong unggan”, a traditional music from Minangkabau community particularly in Unggan, Sumpur Kudus, Sijunjung Regency, West Sumatera Indonesia is classified into genre of “talempong duduak” (rea. Due to its special musical concept and the playing technics, this traditional music is selected as a practising course in the Karawitan Department of Indonesian Institute of Art (ISI Padang Panjang since 1993 till now. In a system of class learning with many students, Talempong Unggan definitely needs supporting methods and learning technics suitable for the course where the students can reach their maximum skills. All the melody of “talempong unggan” that has been made as a material of practice is transcribed to the system of numeric notation and rhythm motive of “gendang” and “aguang” which is written into signs and special notation. All of qualitative data is formulated into finding methods, technics and etude of learning ensamble of Talempong Unggan the traditional music that learned in Karawitan Department of ISI Padang Panjang. Key words: Talempong Unggan, Methods, Technics, Etude

  19. Las Ciencias experimentales en el aula de Educación Infantil: El ciclo del agua

    OpenAIRE

    Ribera Morán, María

    2014-01-01

    Este proyecto se basa en el ciclo de agua en relación a las ciencias experimentales, y enfocado al tercer curso del segundo ciclo de Educación Infantil, con alumnos de 5 a 6 años. En él se expondrán los diferentes autores que han dado lugar a este tipo de pedagogía activa, la metodología que se llevará a cabo, los objetivos que deberán alcanzar los alumnos, la programación y los procesos de evaluación que se pretenden, así como un apéndice con las actividades detalladas. Grado en Educación...

  20. Etude de quelques paramètres biologiques de Pseudotheraptus ...

    African Journals Online (AJOL)

    , São Paulo, 359 pp. Sanon A. & Ouedraogo P.A., 1998. Etude de la variation des paramètres démographiques de Callosobruchus maculatus F. et de ses parasitoïdes Dinarmus basalis Rond et. Eupelmus vuilleti Crawf sur le niébé dans.

  1. 67 Etude physicochimique de l'huile essentielle de Ruta ...

    African Journals Online (AJOL)

    AKA BOKO

    13]. Tableau 1 : Etude bioclimatique des six zones d'études. Caractères. Zones. Longitude. Latitude. Altitude. Climat. Ghazaouet. 1°`52'. 35°46'. 45 m. Semi-aride à hiver tempéré. Ouzidane. 1°19'`. 34°55'. 650 m. Semi-aride à hiver chaud.

  2. etude comparative de l'effet de souches de champignons ...

    African Journals Online (AJOL)

    ACSS

    2015, African Crop Science Society. ETUDE COMPARATIVE DE L'EFFET DE SOUCHES DE ... Auteur correspondant : elhadjmalickleye@yahoo.fr. (Received 2 June, 2015; accepted 30 July, 2015). RESUME ..... aux résultats des travaux de plusieurs auteurs dont Daft et El-Giahmi (1976), Mosse (1981),. Parvathi et al.

  3. Ciencias Experimentales en la Educación Infantil y en la Educación Primaria

    OpenAIRE

    Naves Pineda, Francisco Javier; Feliu Ortega, María José; Fernández-Lorenzo, Concepción

    2010-01-01

    Este curso engloba los conocimientos básicos que deben ser adquiridos por los alumnos en los grados de Magisterio en Educación Infantil y en Educación Primaria sobre las Ciencias Experimentales. De esta forma, se desarrollan temas que versan sobre la materia, la energía, la luz, los estados de agregación de la materia, etc, y se incluyen los conocimientos sobre el entorno que nos rodea desde un punto de vista físico y químico.

  4. Etude ethnobotanique des plantes hépatotropes et de l'usage ...

    African Journals Online (AJOL)

    Etude ethnobotanique des plantes hépatotropes et de l'usage traditionnel de Gomphrena celosioides Mart. (Amaranthaceae) au Bénin. MM Sangare, H Sina, J Dougnon, B Bayala, J-M Ategbo, KL Dramane ...

  5. The Effect of Instruction on Sixth Grade Band Students' Abilities to Self-Rate Etude Performance

    National Research Council Canada - National Science Library

    Kruse, Nathan B

    2006-01-01

    .... Sixth grade band students (N = 36) from a Midwestern state performed and recorded an original etude and then critically evaluated their own rhythmic accuracy using a researcher-constructed rating scale...

  6. Análisis de Sistemas Experimentales de Integración Peces-Pollos.

    Directory of Open Access Journals (Sweden)

    Roberto Trejo Albarrán

    2012-02-01

    Full Text Available In this work the objective was to evaluate four treatments using dung of different kinds from experimental cultures, estimating their efficiency in relation to pisciculture production and the characteristics of each pond. The work was carried out in the Laboratorio de Hidrobiología of the Universidad Autónoma del Estado de Morelos (UAEM in Cuernavaca, Morelos, Mexico, in fiberglass ponds with albinotic Oreochromis niloticus. Analysis was made of plankton, as well as bacteriological, dietectic and piscicultural growth and the physical chemistry of water. Fresh chicken excrement showed variations in the amount of nutriments. Abundance of phytoplankton was from 17,008 to 70,080 org/ml. The most abundant was Closterium sp. In zooplankton, total abundance was from 302 to 1,706 org/ml. The dominant zooplankton was Moina sp. with a yield from 22 to 117 g/m2/ 6 months. Considering these findings, it was observed that the digested chicken dung was the most efficient of the four. Pathogenic enterobacteria were always present. En este trabajo, el objetivo fue evaluar cuatro tratamientos utilizando estiércoles de diferentes tipos en cultivos experimentales, estimando su eficiencia en relación a la producción piscícola y las características de cada estanque. Se llevó a cabo en el Laboratorio de Hidrobiología de la UAEM en Cuernavaca, Morelos, México; en estanques de fibra de vidrio, con Oreochromis niloticus albina. Se realizaron análisis del plancton, bacteriológicos, bromatológicos, crecimiento piscícola y fisicoquímicos del agua. Las excretas frescas de pollo presentaron variaciones en la cantidad de nutrimentos. Las abundancias de fitoplancton fueron de 17,008 a 70,080 org/ml. Los más abundantes fueron Closterium sp. En el zooplancton, las abundancias totales fueron de 302 a 1,706 org/ml. El dominante fue Moina sp. El rendimiento fue de 22 a 117 g/m2/6 meses. Considerando lo anterior se observó que la gallinaza digerida fue el esti

  7. Enfermedad de Huntington: modelos experimentales y perspectivas terapéuticas

    Directory of Open Access Journals (Sweden)

    Teresa Serrano Sánchez

    2011-01-01

    Full Text Available La enfermedad de Huntington (EH es un trastorno degenerativo de origen hereditario. Hasta el momento no existe un tratamiento efectivo para la enfermedad que inexorablemente después de transcurridos 15 a 20 años, evoluciona hacia la incapacidad total o la muerte. En este trabajo se revisan las características clínicas y morfológicas de la EH y los modelos experimentales más utilizados para su estudio tomando como fuente, los artículos indexados en la base de datos Medline publicados en los últimos 20 años. Se valoran las ventajas y desventajas de estos modelos y su perspectiva para el desarrollo de ensayos clínicos. El consenso de lo reportado plantea que de los modelos tóxicos, los inducidos por neurotoxinas tales como el ácido quinolínico parecen ser los más adecuados para reproducir las características neuropatológicas, y por otro lado los modelos genéticos contribuyen con más evidencias al conocimiento del origen etiológico de la enfermedad. Numerosos tratamientos han sido aplicados en el manejo de las manifestaciones clínicas que aparecen en la EH, sin poder detener o disminuir las afectaciones que derivan de la pérdida neuronal. La sintomatología clínica ha sido posible reproducirla, al menos en parte, en animales de experimentación lo que ha permitido realizar ensayos terapéuticos. Desde el punto de vista de tratamiento, lo que más promisorio parece ser, es el trasplante de fuentes celulares y dentro de ellas las no neurales, que implican menor censura ética y mayor factibilidad de obtención para la aplicación en los enfermos. Por otro lado el desarrollo de la tecnología del ARN interferente, emerge como una herramienta terapéutica potencial para el tratamiento de la EH, así como para responder interrogantes básicas relacionadas con el desarrollo de la enfermedad.

  8. Enfermedad de Huntington: modelos experimentales y perspectivas terapéuticas

    Directory of Open Access Journals (Sweden)

    Blanco Lezcano Lisette

    2011-04-01

    Full Text Available La enfermedad de Huntington (EH es un trastorno degenerativo de origen hereditario. Hasta el momento no existe un tratamiento efectivo para la enfermedad que inexorablemente después de transcurridos 15 a 20 años, evoluciona hacia la incapacidad total o la muerte. En este trabajo se revisan las características clínicas y morfológicas de la EH y los modelos experimentales más utilizados para su estudio tomando como fuente, los artículos indexados en la base de datos Medline publicados en los últimos 20 años. Se valoran las ventajas y desventajas de estos modelos y su perspectiva para el desarrollo de ensayos clínicos. El consenso de lo reportado plantea que de los modelos tóxicos, los inducidos por neurotoxinas tales como el ácido quinolínico parecen ser los más adecuados para reproducir las características neuropatológicas, y por otro lado los modelos genéticos contribuyen con más evidencias al conocimiento del origen etiológico de la enfermedad. Numerosos tratamientos han sido aplicados en el manejo de las manifestaciones clínicas que aparecen en la EH, sin poder detener o disminuir las afectaciones que derivan de la pérdida neuronal. La sintomatología clínica ha sido posible reproducirla, al menos en parte, en animales de experimentación lo que ha permitido realizar ensayos terapéuticos. Desde el punto de vista de tratamiento, lo que más promisorio parece ser, es el trasplante de fuentes celulares y dentro de ellas las no neurales, que implican menor censura ética y mayor factibilidad de obtención para la aplicación en los enfermos. Por otro lado el desarrollo de la tecnología del ARN interferente, emerge como una herramienta terapéutica potencial para el tratamiento de la EH, así como para responder interrogantes básicas relacionadas con el desarrollo de la enfermedad.

  9. L'etude de l'InP et du GaP suite a l'implantation ionique de Mn et a un recuit thermique

    Science.gov (United States)

    Bucsa, Ioan Gigel

    Cette these est dediee a l'etude des materiaux InMnP et GaMnP fabriques par implantation ionique et recuit thermique. Plus precisement nous avons investigue la possibilite de former par implantation ionique des materiaux homogenes (alliages) de InMnP et GaMnP contenant de 1 a 5 % atomiques de Mn qui seraient en etat ferromagnetique, pour des possibles applications dans la spintronique. Dans un premier chapitre introductif nous donnons les motivations de cette recherche et faisons une revue de la litterature sur ce sujet. Le deuxieme chapitre decrit les principes de l'implantation ionique, qui est la technique utilisee pour la fabrication des echantillons. Les effets de l'energie, fluence et direction du faisceau ionique sur le profil d'implantation et la formation des dommages seront mis en evidence. Aussi dans ce chapitre nous allons trouver des informations sur les substrats utilises pour l'implantation. Les techniques experimentales utilisees pour la caracterisation structurale, chimique et magnetique des echantillons, ainsi que leurs limitations sont presentees dans le troisieme chapitre. Quelques principes theoriques du magnetisme necessaires pour la comprehension des mesures magnetiques se retrouvent dans le chapitre 4. Le cinquieme chapitre est dedie a l'etude de la morphologie et des proprietes magnetiques des substrats utilises pour implantation et le sixieme chapitre, a l'etude des echantillons implantes au Mn sans avoir subi un recuit thermique. Notamment nous allons voir dans ce chapitre que l'implantation de Mn a plus que 1016 ions/cm 2 amorphise la partie implantee du materiau et le Mn implante se dispose en profondeur sur un profil gaussien. De point de vue magnetique les atomes implantes se trouvent dans un etat paramagnetique entre 5 et 300 K ayant le spin 5/2. Dans le chapitre 7 nous presentons les proprietes des echantillons recuits a basses temperatures. Nous allons voir que dans ces echantillons la couche implantee est polycristalline et les

  10. Electrofisiologia de los receptores y vias neuronales del sistema audio-vestibular en seres humanos y en animales experimentales

    Directory of Open Access Journals (Sweden)

    José A. A. de Oliveira

    1987-01-01

    Full Text Available El estudio electrofisiológico del sistema audio-vestibular en animales y humanos es muy importante en fisiología sensorial y en laberintología. En este estudio se presentan los métodos para el regístro coclear y de los potenciales de acción nerviosa con electrodos implantados en la ventana oval en animales experimentales normales (conejillos de indias. Se muestran también los métodos de registro de respuestas del tallo cerebral en animales experimentales normales y en seres humanos. Además se discutió la importancia de estos métodos en el estudio de la ototoxidad experimental en la evaluación de niños sordos y en la localización de lesiones en el tallo cerebral. Fueron descritos el método de registro de nistagmos por medio de estimulación térmica y rotatoria en animales y humanos, y se mostraron los resultados en individuos normales. Se enfatizó la importancia de la electronistagmografía para el estudio de la ototoxidad experimental y la detección de patologías vestibulares

  11. Study of a case of essential hypoproteinaemia using the isotopes {sup 131}I and {sup 15}N; Etude a l'aide des isotopes {sup 131}I et {sup 15}N d'un cas d'hypoproteinemie essentielle

    Energy Technology Data Exchange (ETDEWEB)

    Dubert, A.; Coursaget, J.; Fallot, P.; Royer, P. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Hopital des Enfants Malades, 75 - Paris (France)

    1959-07-01

    Hypoproteinaemia both human and experimental has been studied with the help of nuclear labelling. A comparative study has been made of the fate of serum proteins labelled by an endogenous path after administration of nitrogen-15 glycine and also of serum albumin labelled by exogenous path using iodine-131. We have determined the biological period of the serum albumin and serum globulins and also the magnitude of the vascular and extravascular pools of serum albumin. In this way it has been possible to measure the speed of replacement of plasma proteins. A presentation of results taken from both clinical observation and experiment leads to a discussion on the pathogenic mechanism of hypoproteinaemia. (author) [French] Les hypoproteinemies humaine et experimentale ont ete explorees a l'aide d'indicateurs nucleaires. Une etude comparative du devenir des proteines seriques marquees par voie endogene, apres administration de glycocolle-{sup 15}N et de l'albumine serique marquee par voie exogene a l'iode-131 a ete realisee. On a determine la periode biologique de la serumalbumine et des globulines seriques ainsi que la grandeur des 'pools' vasculaire et extravasculaire de la serumalbumine. Il a ete ainsi possible d'evaluer la vitesse de renouvellement des proteines plasmatiques. La confrontation des resultats tires de l'observation clinique et de l'experimentation conduit a une discussion sur le mecanisme pathogenique de l'hypoproteinemie. (auteur)

  12. Aspectos Morfológicos – Experimentales de la Tolerancia Biológica de Agentes Hemostáticos Reabsorbibles Implantados en Tejido Óseo.

    OpenAIRE

    Morote y Jurado, José Luis

    2017-01-01

    1.- Se realiza un estudio comparativo de implantaciones en orden a localización, sustancia empleada y tiempo de evolución, utilizando como agentes hemostáticos, cera y esponja de gelatina-cera, realizando un total de 336 implantaciones experimentales en las extremidades del perro, a nivel de las distintas porciones del tejido óseo (cortical, esponjosa, articular), así como en el espesor de las masas musculares, para realizar su posterior examen macrosc&oac...

  13. Desarrollo de estrategias terapéuticas basadas en esteroides neuroactivos y neuroesteroides para el tratamiento de neuropatologías experimentales

    OpenAIRE

    de Nicola, Alejandro Federico; Beauquis, Juan; Coronel, Maria Florencia; Garay, Laura Ines; Gonzalez Deniselle, Maria Claudia; Gonzalez, Susana Laura; Labombarda, Maria Florencia; Pietranera, Luciana; Saravia, Flavia Eugenia; Meyer, Maria; Gargiulo Monachelli, Gisella Mariana; Brocca, María Elvira; Overveld, Lydia Van; Lima, Analia Ethel; Roig, Paulina

    2017-01-01

    Los esteroides activos en el sistema nervioso ("neuroactivos") ejercen actividades neuroprotectoras o neurotóxicas, dependiendo de su estructura química, de las concentraciones circulantes o tisulares, del tipo de receptores intervinientes y de los mecanismos de señalización intracelular empleados. Estas propiedades han sido estudiadas en modelos animales de neuropatologías humanas. Bajo condiciones experimentales que remedan el traumatismo de la médula espinal, dolor neuropático, esclerosis ...

  14. Contribution to the study of detonation initiation by shock in solid explosives (1961); Contribution a l'etude de l'initiation de la detonation par choc dans les explosifs solides (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Fauquignon, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-05-15

    When a shock wave is induced in an explosive, it can initiate chemical reactions which lead more or less rapidly to a stable detonation state. In this study more particular attention was paid to the transition phase, in which has been evaluated the increases in the wave velocity, the pressure, and the electrical conductivity. The influence of the nature of the medium in front of the wave and in contact with the explosive has also been the subject of an experimental study designed to determine the extent to which its nature can be ignored and, subsequently, to characterise the initiation conditions using only the shock intensity induced in the explosive. Finally, the results were generalized for various explosive compositions and led to the development of a possible mechanism for shock initiation. (author) [French] Lorsqu'une onde de choc est induite dans un explosif, elle peut y amorcer des reactions chimiques qui conduisent plus ou moins rapidement a un regime de detonation stable. Dans cette etude, on s'est interesse plus particulierement a la phase transitoire dans laquelle on a evalue l'accroissement de la vitesse d'onde, de la pression et de la conductibilite electrique. L'influence du milieu amont, au contact de l'explosif, a egalement fait l'objet de recherches experimentales de facon a determiner dans quelle mesure on pouvait s'affranchir de sa nature et, par suite, caracteriser les conditions d'initiation par la seule intensite du choc induit dans l'explosif. Enfin, les resultats ont ete generalises a diverses compositions explosives et ont conduit a l'elaboration d'un schema possible du mecanisme de l'initiation par choc. (auteur)

  15. Study of secondary electronic emission in some piezo-electric materials: application to ultrasonic visualization; Etude de l'emission electronique secondaire de quelques materiaux piezoelectriques: application a la visualisation ultrasonore

    Energy Technology Data Exchange (ETDEWEB)

    Marini, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    Methods allowing the visualization of acoustic images appear at the moment to be of great interest in the field of non-destructive testing as well as in that of underwater detection. In order to carry out certain calculations on the operation of an ultrasonic camera, it has been necessary to study the secondary electron emission of some piezoelectric materials liable to be incorporated into the equipment. The secondary electron emission of insulators is a rather complex phenomenon; in order to find a rational explanation for the observations made, a theory has been developed for the energy spectrum of the emitted electrons. The experimental results of this work have then been used to build an ultrasonic visualization installation. Some examples of acoustic images which have been visualized are also presented. (author) [French] Les methodes qui permettent de visualiser des images acoustiques trouvent a l'heure actuelle un grand interet dans le domaine du controle non destructif comme dans celui de la detection sous-marine. De maniere a effectuer certains calculs sur le fonctionnement d'une camera ultrasons, il a ete necessaire d'etudier l'emission electronique secondaire de quelques materiaux piezoelectriques susceptibles d'etre utilises dans sa construction. L'emission electronique secondaire des isolants est un phenomene assez complexe et de maniere a trouver des explications coherentes aux observations effectuees, une theorie du spectre energetique des electrons emis a ete elaboree. Une installation de visualisation ultrasonore a alors ete realisee a partir des donnees experimentales de cette etude. Quelques exemples d'images acoustiques visualisees par cette methode sont egalement presentees. (auteur)

  16. Study by {alpha}-particle scattering, of the collective states of closed shell nuclei with 28 neutrons, 28 and 50 protons; Etude des etats a caractere collectif des noyaux au voisinage des couches fermees par diffusion inelastique des particules {alpha}

    Energy Technology Data Exchange (ETDEWEB)

    Bruge, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-01-01

    This report gives the results from a systematic study by 44 MeV {alpha} particle scattering on the collective states of closed shell nuclei with 28 neutrons, 28 and 50 protons especially in the energy region corresponding to the two phonon vibrational triplet. The nuclei studied are: {sup 46}Ti, {sup 48}Ti, {sup 50}Ti, {sup 52}Cr, {sup 54}Fe, {sup 56}Fe, {sup 58}Fe, {sup 58}Ni, {sup 60}Ni, {sup 62}Ni, {sup 64}Ni, {sup 112}Sn, {sup 114}Sn, {sup 116}Sn, {sup 118}Sn, {sup 120}Sn, {sup 122}Sn and {sup 124}Sn. The theoretical analysis has been made with the Austern and Blair model using a phase shift analysis of the elastic scattering. Deformation lengths {delta}{sub I} = {beta}{sub I}R and transition probabilities obtained are compared with several experimental and theoretical data. (author) [French] Ce rapport donne les resultats d'une etude systematique par diffusion de particules {alpha} de 44 MeV des etats collectifs des noyaux au voisinage des couches fermees a 28 neutrons et 28 et 50 protons, specialement dans la region correspondant au triplet vibrationnel a deux phonons. Les noyaux etudies sont: {sup 46}Ti, {sup 48}Ti, {sup 50}Ti, {sup 52}Cr, {sup 54}Fe, {sup 56}Fe, {sup 58}Fe, {sup 58}Ni, {sup 60}Ni, {sup 62}Ni, {sup 64}Ni, {sup 112}Sn, {sup 114}Sn, {sup 116}Sn, {sup 118}Sn, {sup 120}Sn, {sup 122}Sn et {sup 124}Sn. L'analyse theorique a ete faite a l'aide du modele de Austern et Blair utilisant une analyse en dephasages de la diffusion elastique. Les longueurs de deformation {delta}I = {beta}{sub I}R obtenues pour chaque niveau sont comparees a plusieurs donnees experimentales et theoriques. (auteur)

  17. E. P. R. spectroscopic study of nitroxide mono- and bi-radicals; Etude par spectroscopie de resonance paramagnetique electronique de monoradicaux et de biradicaux nitroxydes

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, H. [Commissariat a l' Energie Atomique, Grenoble, 38 (France). Centre d' Etudes Nucleaires

    1967-07-01

    experimentales d'etude de produits parfaitement bien definis au point de vue structure chimique. L'etude par resonance paramagnetique electronique de monoradicaux nitroxydes conduit a la determination des axes et des elements du tenseur d'interaction hyperfine electron-noyau d'azote et du tenseur d'anisotropie du facteur de Lande: les resultats sont relies a la structure electronique des radicaux. On interprete qualitativement l'influence du solvant sur les elements des tenseurs, ainsi que les elargissements selectifs des raies hyperfines en milieu visqueux. Dans les biradicaux nitroxydes, la structure hyperfine depend non seulement des interactions magnetiques propres a chaque monomere, mais egalement de la grandeur de l'interaction d'echange separant les etats singulet et triplet du dimere; les biradicaux etudies ici sont les premiers composes organiques pour lesquels l'influence de l'echange sur la structure hyperfine est clairement mise en evidence. La presence de deux electrons non apparies introduit egalement une interaction magnetique dipolaire electron-electron, que l'on peut mettre a profit, dans le cas d'un echange intermediaire, pour determiner le signe de l'echange en etudiant le biradical dans un cristal liquide. Ces composes presentent egalement des elargissements selectifs de transitions hyperfines lorsque la viscosite du solvant croit. La theorie utilisee pour interpreter les largeurs de raie des monoradicaux est etendue au cas des biradicaux; elle rend compte des resultats experimentaux si l'on introduit simultanement les anisotropies des facteurs de Lande et des interactions dipolaires electrons-noyaux et electron-electron, en conduisant a une autre determination du signe de l'echange. (auteur)

  18. Etude de la distribution des champs magnetostatiques dans une section d'essais de type CANDU chauffee par effet de joule

    Science.gov (United States)

    Hall, Darren

    Parmi tous les parametres physiques consideres lors de l'analyse de surete d'un reacteur nucleaire, le flux de chaleur critique (FCC) fait partie des plus importants. Afin d'etudier le FCC sous des conditions experimentales relativement securitaires, la chaleur degagee par le combustible nucleaire peut etre reproduite grâce a l'effetet de Joule. Or, afin de generer la puissance thermique necessaire pour les experiences sur le FCC des reacteurs CANDU, des courants electriques tres eleves de l'ordre de plusieurs dizaines de milliers d'amperes sont requis ce qui genere un champ magnetostatique tres intense capable d'interagir avec la section d'essais et l'instrumentation. Consequemment, l'industrie nucleaire est preoccupee par les effets de ce champ magnetique sur les donnees collectees et par les forces d'origine magnetique agissant sur le systeme. Dans ce contexte, le travail presente dans ce memoire de maitrise vise l'implementation d'une methodologie de calcul capable de fournir une information detaillee sur le champ magnetique engendre par ces courants. Toutefois, etant donne la complexitee du systeme, une etude magnetostatique appropriee requiert une methode numerique afin d'obtenir une distribution fiable du champ magnetique a travers differentes structures de la section d'essais. a cet effet, nous considerons dans le cadre de ce memoire le volume integral equation method (VIEM), une methode bien etablie basee sur les solutions integrales des equations de Maxwell. Plus precisement, nous employons le VIEM afin d'etudier la distribution du champ magetique a l'interieur de la section d'essais et pour determiner l'influence des prises concues pour le branchement des capteurs de pression sur la symetrie de cette distribution. Etant donne que les methodes integrales incluent les conditions aux limites et par consequent ne requierent pas l'emploi d'un critere de convergence, nous proposons une nouvelle technique de discretisation. L'emploi de cette procedure nous

  19. Control por Modos Deslizantes y Planitud Diferencial de un Convertidor de CD/CD Boost: Resultados Experimentales

    Directory of Open Access Journals (Sweden)

    R. Silva-Ortigoza

    2008-10-01

    Full Text Available Resumen: En este trabajo se presenta el control del convertidor de potencia de CD a CD Boost. En este sistema existen dos problemas de control, a saber; la regulación alrededor de un punto de equilibrio y la de seguimiento de trayectoria del voltaje de salida. Nosotros enfocamos nuestra atención al segundo problema de control. Debido a las propiedades de fase que satisface este convertidor, para realizar la tarea de seguimiento de trayectoria se diseña un controlador indirecto basado en modos deslizantes en combinación con planitud diferencial, el cual permite el seguimiento de trayectoria de la variable de fase no mínima (voltaje basado en el seguimiento de trayectoria de la variable de fase mínima (corriente. La síntesis de este controlador se realiza con la ayuda de una tarjeta de adquisición de datos National Instruments™ PCI-6025E junto con el software de aplicación MATLAB®-Simulink®. Se aplica este controlador al prototipo del convertidor Boost desarrollado y se obtienen resultados experimentales satisfactorios. Palabras clave: Control Indirecto, Convertidor de CD/CD Boost, Modos Deslizantes, Planitud Diferencial, Seguimiento de Trayectoria

  20. La interacción dialógica y el proceso de enseñanza en ciencias experimentales

    Directory of Open Access Journals (Sweden)

    Ana Lía Longhi

    2012-10-01

    Full Text Available Esta línea de investigación se origina en 1995 desde de una Tesis de Doctorado y continúa en sucesivos proyectos hasta la actualidad. La problemática educativa, común a todos ellos, es el estudio de las interacciones comunicativas en el aula, particularmente en clases de ciencias experimentales. Si bien el discurso que se conforma en el aula ha sido y es objeto de estudio de diversas disciplinas como Sociología, Lingüística, Pedagogía y Teoría de la Comunicación, muy recientemente comienza a buscar su lugar en el marco teórico de la Didáctica de la Ciencias. Establecer una comunicación que permita la emergencia de un contenido académico, que respete su epistemología y que permita un proceso constructivo en el alumno es un desafío para el docente. Desafío que compromete tanto su capacitación disciplinar y didáctica como dialógica. Analizar esta última nos permite generar elementos para un marco teórico, útiles en la formación docente, como criterios para el análisis de tal capacidad.

  1. Turbulent precipitation of uranium oxalate in a vortex reactor - experimental study and modelling; Precipitation turbulente d'oxalate d'uranium en reacteur vortex - etude experimentale et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Sommer de Gelicourt, Y

    2004-03-15

    Industrial oxalic precipitation processed in an un-baffled magnetically stirred tank, the Vortex Reactor, has been studied with uranium simulating plutonium. Modelling precipitation requires a mixing model for the continuous liquid phase and the solution of population balance for the dispersed solid phase. Being chemical reaction influenced by the degree of mixing at molecular scale, that commercial CFD code does not resolve, a sub-grid scale model has been introduced: the finite mode probability density functions, and coupled with a model for the liquid energy spectrum. Evolution of the dispersed phase has been resolved by the quadrature method of moments, first used here with experimental nucleation and growth kinetics, and an aggregation kernel based on local shear rate. The promising abilities of this local approach, without any fitting constant, are strengthened by the similarity between experimental results and simulations. (author)

  2. Experimental study of the iron - smectite system in the presence of a solution at 80 at 300 deg; Etude experimentale du systeme fer-smectite en presence de solution a 80 deg et 300 deg

    Energy Technology Data Exchange (ETDEWEB)

    Guillaume, D

    2002-04-01

    One of the concepts proposed for the storage of nuclear wastes consists in the use of several confining barriers placed between the waste and the biosphere. Vitrified wastes are placed in steel containers surrounded by compacted smectite (engineered barrier). The whole is placed in the geological deep site (geological barrier, granite or argilite). The prediction of the evolution of the performances of the engineered barrier (low permeability, high swelling and sorption capacities) necessitates the study of the long-term stability of its mineral constituents under the conditions of the repository. The aim is to determine the nature and the chemistry of potential newly-formed phases resulting from the temperature increase due to disintegration reactions of the wastes, the presence of fluids coming from the geological barrier, and from the liberation of iron due to the degradation of the containers. Natural systems (in particular geothermal systems and sedimentary basins) give information concerning the possible evolutions of clay minerals. However, the potential availability of metallic iron makes a particular case of the nuclear waste storage. The aim of this experimental study is to put to evidence the chemical and mineralogical transformations of the iron-clay system at 80 deg C and 300 deg C, in the presence of a solution, so as to predict the possible transformations of a bentonite placed in the deep storage conditions of radioactive wastes. Several sets of experiments were carried out to study the reactivity of the MX80 bentonite in the presence of a solution ([CI]=3.10{sup -2} molal, Na/Ca=5,5 and liquid/rock ratio of 10) in absence or in presence of iron (magnetite + hematite or iron + magnetite) at 80 deg C or 300 deg C, and over periods ranging from 1 day to 9 months. Run products were submitted to multi-technique and multi-scale characterisation: X-ray diffraction, scanning electron microscopy, transmission electron microscopy (HR imaging, EDS and EELS) transmission Moessbauer spectroscopy, ICP AES and ICP MS analyses of solutions. The EQ3/6 geochemical code was used to simulate the experiments carried out and compare with the evolutions of the system in the given conditions. A new method for the punctual determination of the valence of iron in clay minerals was developed, using electron energy loss spectroscopy (EELS) on TEM. The valence of iron in a sample is determined by measuring the chemical shift of the L{sub 3} edge of iron or from the decomposition of this edge. The acquisition with TEM of the valence of iron (EELS) and the elemental analysis (EDS) from the same micro-volume (resolution < 100 nm) enables to calculate structural formulae at the particle scale and to point out variations among a population of clay particles. Simulations carried out with the EQ3/6 chemical code enable the validation of the equilibrium compositions of the mineralogical assemblages observed after 9 months experiments. They also enable to point out different reaction kinetics as a function of the experimental system. Experiments carried out at 80 deg C show that whatever the experimental system, no significant evolution of the mineralogy and crystallo-chemistry of the clay sample is observed. At 300 deg C, the di-octahedral smectite transforms to high charge tri-octahedral smectite. This transformation is triggered in the presence of iron oxides (magnetite + hematite) and run samples are enriched in iron. In the presence of metallic iron and magnetite, this evolution is very fast and followed by the formation of Fe-chlorite (close to amesite composition). Experiments carried out with a metallic iron plate as the source of iron and placed in the middle of the experimental sample, enable to point out spatial zoning in the distribution of the newly-formed chlorites. Far from the iron plate an Fe-Mg-chlorite is formed, whereas it is almost pure Fe-chlorite at the contact with the plate and its formation is faster. (authors)

  3. Interactions between fluids and natural clay rich sediments: experimental study in conditions simulating radioactive wastes underground storage; Interactions entre fluides et sediments argileux naturels: etude experimentale dans des conditions simulant un stockage souterrain de dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Roubeuf, V

    2000-10-15

    The behaviour of clay rich sediments, especially an argilite from Oxfordian of Haute-Marne, a siltite from Albian series of Marcoule (Gard) and a bentonite from Wyoming, were experimentally studied under physical-chemical conditions close of those of an underground radioactive waste storage. The several steps of the creation of the storage in deep formation were simulated experimentally, in particular: - the effect due to oxidation at ambient temperature and moisture degree related to the arrival of air in the gallery, was tested, especially the interaction between acid fluids generated at the micron-scale of the altered pyrite micro-site and the surrounding minerals of the sediment, - the alteration due to weathering (damping/drying cycles) to simulate the effect of a surface storage of the sediments, - and finally, water-rock interactions at 80 and 200 deg C, which reproduce the thermic stress induced by the deposit of type C radioactive containers (stage of re-hydration under thermic stress). The various simulations lead to rather similar behaviour of minerals in the sediment and solutions. Mineralogical, geochemical and crystallographic analyses show that most minerals in sediments are preserved with no evidence of mineral neo-formation. Nevertheless, the study by X-ray diffraction shows variations in the interlayer spacing in relation with modifications of the hydration states. Changes in the interlayer occupancy of the clays are due to cationic exchange of the sodium of the interlayer by the calcium issued from the dissolution of carbonate and gypsum dissolution. I/S like minerals crystal-chemistry generally display little changes in the tetrahedral and octahedral occupancy and a rather good stability of crystal structure. The cationic exchange capacity (CEC) of the clay sediment display un-significant variations: after the damping/drying cycles, the argilite of Haute-Marne has lost about 15 % of their bulk CEC and the effect of acid micro-environment at pyrite micro-site leads to an increase of the bulk CEC from 3 to 25%. Whatever their initial composition, the experimental solutions acquired a sulphate character in relation with the dissolution of sulphate minerals as gypsum and jarosite fanned during the oxidation of the sediments. Equilibrium between fluids and carbonates in the rock, constitute a predominant rock forming mineral in the studied sediments yield to an important and rapid buffer effect on solutions, which pH ranges between 7,5 and 8,5. The liquid/rock ratio (L/R) of the experience has an influence on the concentrations of the elements resulting from the dissolution of minerals present in the rock (sulphates from pyrites oxidation). Extrapolated ionic concentrations for low L/R ratio typical of the geological formation indicate that the fluid migrating through an oxidised sediment will be enriched in SO{sub 4}{sup 2-},K{sup +}, Ca{sup 2+} and Mg{sup 2+} and therefore significantly distinct from that inferred in the deep sedimentary formations. (author)

  4. Experimental studies of ions and atoms interaction with insulating surface; Etude experimentale de l'interaction rasante d'atomes et d'ions sur des surfaces isolantes

    Energy Technology Data Exchange (ETDEWEB)

    Villette, J

    2000-10-15

    Grazing collisions (<3 deg.) of keV ions and atoms: H{sup +}, Ne{sup +}, Ne{sup 0}, Na{sup +} on LiF (001) single crystal, an ionic insulator, are investigated by a time of flight technique. The incident beam is chopped and the scattered particles are collected on a position sensitive detector providing differential cross section while the time of flight gives the energy loss. Deflection plates allow the charge state analysis. Secondary electrons are detected in coincidence allowing direct measurements of electron emission yield, angular and energetic distribution through time of flight measurements. The target electronic structure characterized by a large band gap, governs the collisional processes: charge exchange, electronic excitations and electron emission. In particular, these studies show that the population of local target excitations surface excitons is the major contribution to the kinetic energy transfer (stopping power). Auger neutralization of Ne{sup +} and He{sup +} ions reveals the population of quasi-molecular excitons, an exciton bound on two holes. Referenced in the literature as trion. A direct energy balance determines the binding energy associated with these excited states of the surface. Besides these electronic energy loss processes, two nuclear energy loss mechanisms are characterized. These processes imply momentum transfer to individual target atoms during close binary collisions or, if the projectile is charged, to collective mode of optical phonons induced by the projectile coulomb field. The effect of the temperature on the scattering profile, the contribution of topological surface defects to the energy loss profile and to skipping motion on the surface are analyzed in view of classical trajectory simulations. (author)

  5. Experimental study of the mechanisms of CO{sub 2} capture by calcium cycle under circulating fluidized bed conditions; Etude experimentale des mecanismes de capture du CO{sub 2} par cycle calcium en lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Hoteit, A

    2006-06-15

    The work undertaken in this Thesis in partnership with department R and D of ALSTOM Power Boilers, CEMEX and the ADEME, relates to the experimental study of various phenomena associated to CO{sub 2} capture under circulating fluidized bed conditions. The size of particles, temperature and the CO{sub 2} concentration have an influence on the limestone calcination reaction. The reaction of carbonation of lime is not total. During successive cycles of calcination/carbonation, the rate of carbonation obtained with hydrated lime is increasingly higher than that obtained with the lime. Under continuously reducing conditions, the decomposition of sulphates present in the bed ashes is not total. This decomposition is total under reduction/oxidation cycles. A modeling of calcination allowed to determine the intrinsic kinetic constants of calcination and carbonation. (author)

  6. Experimental study of an oxygen-hydrogen diffusion flame laden with solid alumina particles; Etude experimentale d'une flamme de diffusion oxygene-hydrogene ensemencee en particules solides d'alumine

    Energy Technology Data Exchange (ETDEWEB)

    Labor, S.

    2003-07-15

    Monocrystalline sapphire microspheres are generated through the melting of alumina (AL{sub 2}O{sub 3}) particles in a flame. The alumina particles are injected in a very peculiar O{sub 2}/H{sub 2} confined diffusion flame as it is a downwards vertical flame having fuel in periphery of a central powdered oxygen jet. Quantitative measurements were carried out (ADL, PIV) and supplemented by a numerical study (N3S-Natur). (1) The laminar behavior of the isothermal conditions is kept through reactive flow. Therefore, particles will mainly collide due to speed gradients. (2) It has been shown that an axial particle will have a transit time int the high temperature zone very different to that of an off-line one. (3) The PIV date proved that the particle density was not homogeneous. (4) The hydrogen jet hardly influences the flame aerodynamic structure. Conversely, the central oxygen jet is at premium due to its effect on both the flame speed and temperature distribution. (author)

  7. Experimental study of the MHD activity associated to the mode m=2, n=1 in the Tore Supra tokamak; Etude experimentale de l`activite MHD associee au mode m=2, n=1 dans le tokamak Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Turlur, S.

    1996-09-20

    In tokamaks such as Tore Supra, the plasma confinement magnetic structure can be severely affected when Magnetohydrodynamic (M.H.D.) instabilities are destabilized. Experimentally, these instabilities are detected as magnetic fluctuations with captors located against the inner wall of the vacuum vessel. Fourier analysis provides amplitude, frequency and wave numbers of magnetic modes. In case of fast or transient phenomena, the analysis of magnetic fluctuations is completed using the singular value decomposition. In this dissertation, these analysis techniques are used to study two specific examples of M.H.D. activity related to the m = 2, n = 1 mode. On Tore Supra, the onset of this mode have strong consequences on the stability of partially or fully non inductive discharges. A regular and persistent sawtooth-like regime is observed on the electronic temperature leading to a significant degradation of the central confinement. Heat exhaust and particle balance are also essential parameters to achieve stationary discharges. On Tore Supra, these are studied with the ergodic divertor which produces stochastic magnetic field lines at the plasma edge. For optimal operating conditions of the ergodic divertor, the growth of the m = 2, N = 1 mode can lead to sudden destruction of magnetic equilibrium. For both cases, understanding and characterization of mechanisms leading to the observed m = 2, n = 1 M.H.D. activity are fundamental to obtain stationary discharges. (author). 115 refs.

  8. Experimental study of X-ray emission in laser-cluster interaction; Etude experimentale de l'emission X issue de l'interaction laser-agregats

    Energy Technology Data Exchange (ETDEWEB)

    Caillaud, T

    2004-09-01

    Rare gas cluster jets are an intermediate medium between solid and gas targets. Laser-cluster jets interaction may generate a great number of energetic particles as X-rays, UV, high harmonics, ions, electrons and neutrons. To understand all the mechanisms involved in such an interaction we need to make a complete study of individual cluster response to an ultra-short laser pulse. We studied the laser interaction with our argon cluster gas jet, which is well characterized in cluster size and density, to enlarge the knowledge of this interaction. We measured absorption, heating and X-ray emission spectra versus laser parameters and clusters size ({approx} 15-30 nm). We show that there is a strong refraction effect on laser propagation due to the residual gas density. This effect was confirmed by laser propagation simulation with a cylindrical 2-dimensional particle code WAKE. The role played by refraction was to limit maximum laser intensity on the focal spot and to increase interaction volume. By this way, X-ray emission was observed with laser intensity not so far from the ionization threshold (few 10{sup 14} W.cm{sup -2}). We also studied plasma expansion both at cluster scale and focal volume scale and deduced the deposited energy distribution as a function of time. Thanks to a simple hydrodynamic model, we used these results to study cluster expansion. X-ray emission is then simulated by TRANSPEC code in order to reproduce X-ray spectra and duration. Those results revealed an extremely brief X-ray emission consistent with a preliminary measure by streak camera (on ps scale). (author)

  9. Experimental study and simulation of fused silica damage initiation by laser pulse irradiation; Etude experimentale et modelisation de l'initiation de l'endommagement de la silice sous irradiation laser impulsionnelle

    Energy Technology Data Exchange (ETDEWEB)

    Bonneau, F.; Combis, J.L.; Vierne, J. [CEA Bruyeres-le-Chatel, Dept. de Physique Theorique et Appliquee, 91 (France)] [and others

    2002-07-01

    In order to resolve problems concerning the understanding and the control of laser-induced damage of silica optical elements, a collaboration between the CEA (CESTA/DLP, DIF/DPTA, and Grenoble/LETI) and different university laboratories has been undertaken. Ultra-pure silica 'model' samples, seeded with gold nano-particles whose diameter does not exceed 5 nm, were made at the LASIM in Lyon. The aim in using these samples is to observe the mechanism of damage initiation that can be attributed to inclusions of nano-metric site. This report presents the different steps encountered during this study: making the samples, the laser-induced damage tests performed at the CESTA, and the 'Nomarski' and 'atomic force' microscope observations of this damage carried out at the Fresnel Institute in Marseille. These samples were also used for a series of experiments using a time-of-flight mass spectrometer at ANL near Chicago. This installation is of great interest because it enables us to combine the laser irradiation of the sample with the chemical identification of material ejected by the sample. A precise evaluation of the quantity of gold atoms emitted during irradiation can thus be obtained from the experimental results. The experimental data is then interpreted, and in particular, compared to, numerical simulations obtained with the DELPOR program. A very encouraging result is the existence of a pre-damage phase at very low fluences that is not detectable by classical optical devices. The experimental means developed for such 'model' samples should be transposable to the analysis of industrial glasses. (authors)

  10. Electron impact experimental study of single and double ionisation of atoms and small molecules; Etude experimentale par impact electronique de l'ionisation simple et double d'atomes et de petites molecules

    Energy Technology Data Exchange (ETDEWEB)

    Naja, A.

    2008-11-15

    (e,2e) and (e,3e) experiments constitute a privileged tool for studying the dynamics of electron impact single and double ionization of small systems, and more generally for contributing to the understanding of the N-body interaction problem. In this work, we have performed such experiments in an unexplored kinematical regime where the momentum transferred to the residual ion is large, so that the ion plays a major role in the interaction process. The experimental results are compared to those of the most sophisticated theoretical models. We have measured the triply differential cross sections (TDCS) for single ionization of He and H{sub 2}. Their comparison allowed showing the presence for the H{sub 2} molecule of Young type quantal interference effects. We then discuss TDCS measurements for Ne and N{sub 2} ionized either on an outer or an inner orbital. The results show the importance of the post collisional interactions and the role played by the nucleus. Finally, we study the competition between different ionization processes of argon: (e,2e) single ionization of the inner 2p shell on the one hand, and a direct (3p{sup -2}) (e,3e) double ionization or an indirect one via the Auger process implying the 2p shell, on the other hand. Under the chosen kinematics, these processes may compete or interfere with each other. The emphasis is put on their respective contribution, particularly for the Auger effect. Several structures observed in the angular distribution of the (e,3e) cross section are attributed to different ionization mechanisms. (author)

  11. Experimental thermal study and numerical simulation of a composite solar wall. Optimization of the energetic performances; Etude thermique experimentale et simulation numerique d`un mur solaire composite. Optimisation des performances energetiques

    Energy Technology Data Exchange (ETDEWEB)

    Zalewski, L.

    1996-11-27

    The objective of this work is the analysis of a passive solar component: the composite solar wall, a building component, which includes an insulating panel located behind the massive wall. This panel has two vents located at the top and at the bottom, which allow the air to circulate from the room to the layer in contact with the back of the massive wall, where it is heated, and then back to the room. The solar energy is transferred to the building by conduction through the massive wall, and then by convection using a thermosyphon phenomenon. The monitoring of 2 solar houses in Verdun-Thierville (Meuse, France) has clearly shown, control issues of the air layer. The wall must be operated as autonomously as possible, to not be a constraint for the occupants and to get an optimization of the energy gains. To solve these problems, a composite solar wall prototype was erected in a test cell at Cadarache and tested in real operating conditions. This allows to use a more complete instrumentation, to have access more easily to the sensors and to study various configurations. The first experiments revealed an inverse thermosyphon phenomenon. To avoid this effect, two systems were designed, tested at Cadarache and then implemented in the walls at Verdun. (author) 77 refs.

  12. Double protection passive pour les equipages de l'helicoptere d'attaque "Tigre" : Concept et etude experimentale (Design and Experimental Study of the Passive Double Hearing Protection for the Crew of the Attack Helicopter "Tiger")

    National Research Council Canada - National Science Library

    Baudou, J; Reynaud, G; Poussin, G; Leger, A

    2005-01-01

    ... naturellement imposee comme axe de travail. Prealablement evalues de facon empirique, des bouchons de type "mousses Quies" ont ete selectionnes pour leur port confortable et leur forte attenuation...

  13. Numerical and experimental study of premixed turbulent hydrogen flame propagation in lean and wet atmosphere; Etude experimentale et numerique de la propagation de flammes premelangees turbulentes dans une atmosphere pauvre en hydrogene et humide

    Energy Technology Data Exchange (ETDEWEB)

    Malet, F

    2005-12-15

    The main objectives of PhD work concern the characterisation of hydrogen flame propagation in air-steam mixture representative of reactor containment atmosphere in severe accident situations. Laminar and turbulent flame regimes were investigated with: (1) spherical bomb is used to perform laminar flame tests. Different parameters were identified: the laminar flame velocity, SL{sup 0}, and flame thickness, d, the integral length scale, LT, and intensity of turbulence, the Lewis and Zeldovich numbers, Le, b, the expansion ratio, s, the product speed of sound Csp. (2) ENACCEF facility dedicated to flame acceleration. This facility is highly instrumented (16 optical windows with PMT, 9 pressure transducers) to follow the flame propagation. The lower part of ENACCEF has 6 gas sampling locations. The mixture is ignited by a spark discharge at the bottom-end using electrodes. Tests performed on ENACCEF show the effect of blockage ratio, obstacles shape and gas composition on flame velocity. Some tests performed on the previous facilities were numerically simulated with TONUS CFD code. (author)

  14. Modeling and experimental study of heat transfer in innovate building components for industrial production; Modelisation et etude experimentale des echanges de chaleur dans des composants innovants de batiment industriels

    Energy Technology Data Exchange (ETDEWEB)

    Lacena-Neildez, A.

    2000-05-15

    The main objective of the thesis is the study of a new roof thermal behaviour with the thermal transfer by radiation and convection in order to propose an alternative to the mechanical air-conditioning in the overseas islands, and to determine the way of improving the energy performance. Two fundamental results were obtained. First, the coating has a great importance in relation with the radiative properties. Secondly, air channel geometries can complete insufficient coatings in their cooling purpose. In this thesis, both experimental and modelling analyses were carried out. A solar simulator was used for the experiment to carry out a comparative study of prototypes. A performance indicator was defined; it is the eliminated flux, because the temperature is not sufficient to describe the heat exchange. At the same time, the radiative properties of coatings were measured and a characterisation of paints allows to start a new research of innovative infrared reflective paints. A mono-dimensional model was developed describing thermal exchanges in an air channel component. A sensibility study was carried out which allows to determine the main parameters. The experimental study validated the model in rear flux, more realistic than stagnation. Finally, the feasibility of this new steel component was concluded by a technical-economical study. (author)

  15. Experimental investigation of the effects of aqueous species on the dissolution kinetics of R7T7 glass; Etude experimentale de l`influence d`especes aqueuses sur la cinetique de dissolution du verre nucleaire R7T7

    Energy Technology Data Exchange (ETDEWEB)

    Gin, S.

    1994-10-01

    This contribution to the study of aqueous corrosion of the French ``R7T7`` reference nuclear containment glass includes a bibliographic survey of prior investigations, highlighting the problems encountered in interpreting the interactions in systems containing clay materials in contact with the glass. An experimental methodology is proposed to investigate the effects of inorganic aqueous species separately from those of a few organic acids on the dissolution mechanisms and kinetics of R7T7 glass at 90 deg. C. The experimental results discussed support the idea that several glass network forming elements may have a kinetically limiting role. The most likely hypothesis to account for the absence of saturation conditions with respect to the glass in certain clay media involves the formation of complexes with kinetically limiting metallic elements such as aluminum released by glass corrosion. This work contributes to a better understanding of the basic mechanisms of nuclear glass dissolution in a geological repository environment. It facilitates the interpretation of glass alteration studies in realistic or actual solutions and may contribute to specifying near field chemical barriers in the form of additives (amorphous silica, aluminum hydroxides or phosphates) around the glass disposal package to enhance the stability of the glass matrix. (author). 148 refs., 40 figs., 32 tabs., 1 append.

  16. Theoretical and experimental study of a modular accelerating structure of travelling waves sections for high gradient tests (MECCANO); Etude theorique et experimentale d`une structure acceleratrice a ondes progressives demontable pour des tests fort gradient (Structure dite ``MECCANO``)

    Energy Technology Data Exchange (ETDEWEB)

    Chanudet, M

    1996-06-04

    A modular system, MECCANO, has been developed at the Laboratoire de l`Accelerateur Lineaire d`Orsay to study the physical and technical phenomena of high electric fields in travelling waves structures in the context of future linear colliders which can reach TeV energies. The behaviour of the electric field inside the section MECCANO is considered from the theoretical point of view with numerical simulations and analytical representations and from the experimental side with low and high power measurements. An infinite and uniform structure is classically described by series of RLC resonant circuits. The basic RF properties of the fundamental mode are given. For a finite section, the matching of a forward or backward travelling wave of any phase advance per cell is also represented by means of RLC circuits. The variations of the reflection and transmission properties of the structure with frequency and a new procedure to match couplers have been modelled and experimentally verified. The electromagnetic behaviour of each cavity and of the whole structure have been studied, the fundamental and first high order modes have been simulated by 2D or 3D codes and measured at low power. The matching of the phase, the amplitude and the reflection level of the accelerator is described. This procedure is found to be extremely delicate due to the abrupt changes in the geometry of the cavities. The structure has been tested at fields superior to 150 MV/m. The behaviour of some materials and surface layers subject to high gradients are presented. (author) 46 refs.

  17. Chemical and radiological toxicity of iodine isotopes. Experimental study on the rat at the perinatal stage; Toxicite chimique et radiologique des isotopes de l'iode. Etude experimentale chez le rat en periode perinatale

    Energy Technology Data Exchange (ETDEWEB)

    Bourahla, K

    2000-07-01

    The recommended prophylactic measure in the case of an exposure to radio-iodine is an excess take of stable iodine. During the perinatal stage, the thyroid is radio-sensible but also fragile with respect to an excess of iodine. This work performed on the rat, treats of the potential thyroidal toxicity of the prophylaxy and analyzes the early radio-lesions induced by {sup 131}I. On the basis of microscopic (optical, electronic, ionic) and dosimetric studies (TSH, T4), four aspects are considered: 1 - the perinatal morpho-functional evolution (F18, J1, J4, J10, J21, J35); 2 - the consequences of an iodine overburden at three moments of the thyroid maturation (F16, F20 and J4); 3 - the effects on the thyroid cells growth of different iodine overburdens (4 g, 20 g, 100 g); and 4 - the radio-toxic effects (after 48 h) of {sup 131}I taken at J5 (30 Gy) and at J35 (900 Gy). This work evidences the following points: 1 - the perinatal evolution of the thyroid tissue of the rat shows ultra-structural and follicular modifications and physiological follicular destructions; 2 - the variability of the iodine overburden effects: hyperactivity for overburdens at F16, tissue destruction with compensated hypothyroidism for overburdens at J5, no recognized thyroidal anomaly for the overburden at J20; 3 - the iodated overburden inhibits the start-up of the S-phase of the cellular cycle at a lower level (1/20); 4 - the {sup 131}I taken at J5 (30 Gy) induces a lysis of the nucleic acids content, while {sup 131}I taken at J35 (900 Gy) induces an important inflammatory reaction and some apoptosis phenomena. In summary, the stable iodine prophylactic measure can have two conjugated effects on the rat: an interesting action of thyroid cells growth inhibition, and a toxic action leading to an hyperactivity or a follicular destruction without hypothyroidism, depending on the maturation stage. The early effects of {sup 131}I seem to be linked with the age. (J.S.)

  18. Experimental study of the vaporization of a droplets injection in a fluidized gas-solid media; Etude experimentale de la vaporisation d'un jet de goutelettes au contact d'un milieu gaz-solide fluidise

    Energy Technology Data Exchange (ETDEWEB)

    Leclere, K.

    2002-09-01

    The quality of feedstock injection in the Fluid Catalytic Process (FCC) is essential to ensure a good vaporization. The vaporization should be fast so that the cracking reaction in the gaseous phase can happen within the short residence time in the riser (a few seconds). Vaporization is helped by a uniform injection of droplets as small as possible as well as a good mixing with the catalyst particles that represent the main heat source. Several models were developed to predict the droplet vaporization in a gas-solid media. However, no experimental validation exists for these models, whose predictions vary (from 1 to several hundreds of milliseconds). The objective of this study was to get a better understanding of the physical phenomena taking place during droplet vaporization. This was done in two steps. First, operating limits had to be defined to ensure an optimal vaporization and to avoid local saturation and agglomerate formation. These limits were precisely determined under laboratory conditions to validate a model that showed that agglomeration does not occur under industrial conditions. Then, a kinematic study of vaporization under operating conditions without agglomerate formation was performed. An original measurement technique was developed to get samples at very short times (tens of milliseconds). Experiments showed that heat transfer was not limiting and that mass transfer was the limiting process during vaporization. The developed model was thus based on mass transfer through a boundary layer. The validation of this model in a dense fluidized bed justified its application to operating conditions were the bed voidance is higher. A detailed study of operating parameters will help determine how to improve vaporization. (author)

  19. Modelling and experimental study of the behavior of radon and radon decay products in an enclosure. Application to houses; Modelisation et etude experimentale du comportement du radon et de ses descendants dans une enceinte confinee. Application a une habitation

    Energy Technology Data Exchange (ETDEWEB)

    Gouronnec, A.M.

    1995-02-03

    Since the eighties, more and more studies were performed about radon and its decay products in houses with one of the aim being the estimation of the dose received by their inhabitants. Then, the principal objective of this work is to describe the behaviour of radon and its decay products within a dwelling. In the first part to the report, a few definitions are given and data from literature give an idea of indoor radon and radon decay products activities and/or size distribution. Aspects of dosimetry are presented too. In the second part of the work, a mathematical model, called `PRADDO` of Physic of Radon and radon Decay products in Domestic environment is developed on the basis of the classical model written by Jacobi in 1972. On the one hand, it has to predict radon decay products activities in systems consisting in one or more enclosure(s), from radon activity and from ambient aerosol concentration and size distribution. On the other hand, one part of the model is assigned to study the influence of the entry model parameters variation on the calculated quantities. Then, in the third part of the work, two experimental studies are realised in order to compare measurements to modelization. The first experimentation is a laboratory work, made on the test bench ICARE from IPSN, and the second one consists in describing the basement of an occupied house from Brittany. In the two cases, the comparison between experiments and modelling shows a good agreement if particles are present in the air, but any conclusion is made when is no aerosol in the enclosure. (author). 158 refs., 81 figs., 42 tabs.

  20. Determination of the turbulent viscosity inside a strongly heated rectangular jet: experimental and numerical studies; Determination de la viscosite turbulente dans un jet rectangulaire fortement chauffe: etudes experimentale et numerique

    Energy Technology Data Exchange (ETDEWEB)

    Sarh, B.; Gokalp, I.; Sanders, H. [Centre National de la Recherche Scientifique (CNRS), 45 - Orleans-la-Source (France)

    1997-12-31

    In the framework of the studies carried out by the LCSR on variable density flows and diffusion turbulent flames, this paper deals with the study of the influence of density variation on the characteristics of a heated rectangular turbulent jet emerging in a stagnant surrounding atmosphere and more particularly on the determination of turbulent viscosity. The dynamical field is measured using laser-Doppler anemometry while the thermal field is measured using cold wire anemometry. A numerical predetermination of the characteristics of this jet, based on a k-{epsilon} modeling, is carried out. (J.S.) 6 refs.

  1. Synthesis of zirconium by zirconium tetrachloride reduction by magnesio-thermia. Experimental study and modelling; Elaboration de zirconium par reduction de tetrachlorure de zirconium par magnesothermie. Etude experimentale et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Basin, N

    2001-01-01

    This work deals with the synthesis of zirconium. The ore is carbo-chlorinated to obtain the tetrachloride which is then purified by selective condensation and extractive distillation. Zirconium tetrachloride is then reduced by magnesium and the pseudo-alloy is obtained according to the global following reaction (Kroll process): ZrCl{sub 4} + 2 Mg = 2 MgCl{sub 2}. By thermodynamics, it has been shown that the volatilization of magnesium chloride and the formation of zirconium sub-chlorides are minimized when the combined effects of temperature and of dilution with argon are limited. With these conditions, the products, essentially zirconium and magnesium chloride, are obtained in equivalence ratio in the magnesio-thermia reaction. The global kinetics of the reduction process has been studied by a thermal gravimetric method. A thermo-balance device has been developed specially for this kinetics study. It runs under a controlled atmosphere and is coupled to a vapor tetrachloride feed unit. The transformation is modelled supposing that the zirconium and magnesium chloride formation result: 1)of the evaporation of magnesium from its liquid phase 2)of the transfer of magnesium and zirconium tetrachloride vapors towards the front of the reaction located in the gaseous phase 3)of the chemical reaction. In the studied conditions, the diffusion is supposed to be the limiting process. The influence of the following parameters: geometry of the reactive zone, temperature, scanning rate of the argon-zirconium tetrachloride mixture, composition of the argon-zirconium tetrachloride mixture has been experimentally studied and confronted with success to the model. (O.M.)

  2. Contribution to the experimental study of charmed hadrons produced with hyperon beams (WA89 experiment); Contribution a l'etude experimentale des hadrons charmes produits avec un faisceau d'hyperons (experience WA89)

    Energy Technology Data Exchange (ETDEWEB)

    Berat, C

    1996-10-15

    Since 1989 the author has been involved in the CERN WA89 experiment that is dedicated to the production of charmed hadrons with hyperon beams. The features and the experimental setting of WA89 are presented in the first chapter. The second chapter is dedicated to the on-line and off-line identification of {lambda}{sup 0} particles produced in charmed particles decay. The former is made through an adequate trigger and the latter is an event filter based on a fast identification criterion of a likely decay of {lambda}{sup 0}. The identification of {lambda}{sup 0} has required the development of algorithms to test the validity of the track reconstruction in the decay area between the target and the spectrometer and to check the validity of the identification of the decay vertex of {lambda}{sup 0}. The last chapter is dedicated to data analysis. The identification of D{sub S} mesons in K{sup +}K{sup -}{pi} final state is detailed. An accurate determination of the D{sub S} production cross-section is not yet possible because of the low statistics but it was possible to make a preliminary assessment that has given: {sigma} = (1.5 {+-} 0.7) {mu}b/nucleon with x{sub F} > 0. (A.C.)

  3. Experimental study of improvement of exchanged power in gases by catalytic dissociation: ammonia (1961); Etude experimentale de l'amelioration des echanges de chaleur avec les gaz par dissociation catalytique: ammoniac (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Perroud, P. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires; De La Harpe, A. [Centre National de la Recherche Scientifique(CNRS), 75 - Paris (France)

    1961-07-01

    Rates of ammonia dissociation and resulting coefficients of improvement of exchanged power have been measured in an annular channel under following conditions: mean wall temperature until 1500 deg. C (tungsten rod, diameter 3 mm), mass velocity until 11 g/cm{sup 2}.s and absolute pressure between 1.5 and 7 kg/cm{sup 2}. Rate of dissociation is mainly function of wall temperature and total mass flow rate of ammonia; it depends little on entrance gas temperature and is practically independent of pressure. Apparent coefficients of improvement of exchanged power under above conditions (including radiation) have reached 1.8; this maximum was obtained for a mean wall temperature of 1250 deg. C. These coefficients decrease when Reynolds number increases. Finally, a theoretical analysis of the phenomenon is given as well as possibilities of application. (authors) [French] Les taux de dissociation d'ammoniac et les coefficients d'amelioration de puissance echangee resultants ont ete mesures en espace annulaire dans les conditions suivantes: temperature moyenne de paroi jusqu'a 1500 deg. C (barreau de tungstene de diametre 3 mm), vitesse massique jusqu'a 11 g/cm{sup 2}.s et pression absolue comprise entre 1,5 et 7 kg/cm{sup 2}. Le taux de dissociation est surtout fonction de la temperature de paroi et du debit en masse total d'ammoniac; il depend peu de la temperature d'entree du gaz et est pratiquement independant de la pression. Les coefficients d'amelioration apparents de la puissance echangee dans les conditions d'experience (rayonnement compris) ont atteint 1,8. Ce maximum observe se place vers une temperature moyenne de la paroi de 1250 deg. C. Ces coefficients decroissent quand le nombre de Reynolds de l'ecoulement croit. Finalement, une analyse theorique du phenomene est donnee ainsi que les perspectives d'applications. (auteurs)

  4. Experimental and numerical study of two-phase flows at the inlet of evaporators in vapour compression cycles; Etude experimentale et numerique d'ecoulements diphasiques a l'entree des evaporateurs de cycles thermodynamiques

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, M

    2007-09-15

    Maldistribution of liquid-vapour two phase flows causes a significant decrease of the thermal and hydraulic performance of evaporators in thermodynamic vapour compression cycles. A first experimental installation was used to visualize the two phase flow evolution between the expansion valve and the evaporator inlet. A second experimental set-up simulating a compact heat exchanger has been designed to identify the functional and geometrical parameters creating the best distribution of the two phases in the different channels. An analysis and a comprehension of the relation between the geometrical and functional parameters with the flow pattern inside the header and the two phase distribution, has been established. A numerical simulations of a stratified flow and a stratified jet flow have been carried out using two CFD codes: FLUENT and NEPTUNE. In the case of a fragmented jet configuration, a global definition of the interfacial area concentration for a separated phases and dispersed phases flow has been established and a model calculating the fragmented mass fraction has been developed. (author)

  5. Experimental and numerical study of jet impingement heat transfer: application to turbojet engines; Etude experimentale et numerique des transferts thermiques par impact de jets(s): application aux moteurs aeronautiques

    Energy Technology Data Exchange (ETDEWEB)

    Brevet, Ph.

    2001-11-01

    The optimization of turbojet engines internal cooling systems is nowadays one of the main challenges engineers have to cope with. The current work presents an experimental and numerical study of the jet impingement cooling technique which is used in particular to cool gas turbine blades. This study was initiated and supported by SNECMA Moteurs. It investigates the heat transfer characteristics of different configurations of impinging jets on a flat plate. The heated-thin-foil technique is used jointly with infrared thermography to evaluate accurately the local wall heat transfer coefficient. The influence of the injection Reynolds and Mach numbers, the impingement distance, the confinement, and the nozzle geometry is evaluated on a single axisymmetric impinging jet configuration. 'Three-temperatures convection problems' are considered on this configuration as well when jet velocities are high and when jets are hotter than the environment in which they develop. A second configuration deals with in-line and staggered arrays of confined impinging jets. The geometry is closed to the geometries encountered within turbine blade internal cooling systems and the problem is solved in terms of cooling efficiency and optimization. Finally the ability of MSD, a CFD code developed by ONERA, and FLUENT to model heat transfer generated by jet impingement is evaluated on a single axisymmetric jet configuration. (author)

  6. Experimental study of the influence of partner structure in the fusion of the almost symmetrical systems; Etude experimentale de l`influence de la structure des partenaires dans la fusion de systemes presque symetriques

    Energy Technology Data Exchange (ETDEWEB)

    Stodel-Le Lay, Christelle [Lab. de Physique Corpusculaire, Caen Univ., 14 - Caen (France)

    1998-12-04

    The cross-sections for the formation of evaporation residues in {sup 70}Zn and {sup 86}Kr reactions with {sup 150}Nd and {sup 130,136}Xe isotopes were measured for excitation energies of the compound nuclei ({sup 216,220,222}Th) varied from 7 MeV to 70 MeV, at the linear accelerator UNILAC of the nuclear facility GSI, Darmstadt (Germany). After de-excitation by evaporation (xn,pxn and {alpha}xn), the residual nuclei are separated from the primary beam and from spurious reaction products by the velocity filter SHIP and implanted into a silicon localization detector. Their subsequent decay via alpha particles with characteristic energies allows us to identify them and to deduce their yields. Experimental fusion-evaporation excitation functions are compared with those leading to the same compound nuclei obtained with other projectile and target combinations and with those calculated with a code developed at GSI. This code allows us to evaluate the evolution of the fission probability as a function of the incident energy for each system. The variation of cross-sections and of the fusion probability is studied as a function of the macroscopic and microscopic variables of the partners. For the synthesis of super-heavy elements, these results demonstrate quantitatively the interest in using partners of fusion with closed shell structures and rich in neurons (the fusion cross-section increases by a factor of 9 for a complementary pair of neutrons). On the other hand, closed shell compound nuclei do not influence the fusion cross-section. It will be worth synthesizing isotopes approaching the predicted stability region, nuclei with Z greater than 110 using neutron rich projectiles coming from secondary beams. (author) 104 refs., 71 figs., 11 tabs.

  7. Numerical and experimental study of the beam dynamics of CANDELA photo-injector and associated instrumentation; Etude numerique et experimentale de la dynamique du faisceau du photo-injecteur CANDELA et instrumentation associee

    Energy Technology Data Exchange (ETDEWEB)

    Devanz, Guillaume [Paris-6 Univ., 95 Paris (France)

    1999-03-04

    Laser triggered radiofrequency guns are the most luminous electron sources allowing to reach the performances requested by highly demanding applications like the e{sup +}/e{sup -}linear colliders and the short wave free electron lasers. CANDELA is a band S photo-injector triggered by a sub-picosecond laser. It allows reaching peak currents of hundred of amperes at average energies higher than 2 MeV. The original concept of two accelerating cavities aims at minimizing the transverse and longitudinal emittances following the Gao's principles. From practical reasons the operating parameters, particularly the laser pulse duration, do not correspond to those considered in the design. Hence, numerical simulations were performed to evaluate the gun's performances in experimental environment. The study of a stabile injector operation resulted in evolutions with consequences in the phase control systems implying the laser and the HF (Hyper Frequency) source. The beam transverse and longitudinal characteristics have been measured as a function of the main parameters i.e., the beam charge and the phase shift between the laser and the HF wave. Measurements of the transverse emittance energy dispersion and wave packed duration are presented for several injector configurations. The systems of existing beam measurements have been studied to determine the resolution and the experimental conditions to fulfill, in order to suggest improvements for the CANDELA beam. The experiments with the beam have been compared with numerical simulations. Agreement was obtained within wide ranges of parameters for most of the characteristic beam quantities.

  8. Proton scattering from unstable nuclei {sup 20}O, {sup 30}S, {sup 34}Ar: experimental study and models; Diffusion de protons sur les noyaux instables {sup 20}O, {sup 30}S, {sup 34}Ar: etude experimentale et developpement de modeles

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Elias [Institut de Physique Nucleaire, CNRS - IN2P3, Universite Paris - Sud, 91406 Orsay Cedex (France)

    2000-01-28

    Elastic and inelastic proton scattering from the unstable nuclei {sup 20}O, {sup 30}S and {sup 34}Ar were measured in inverse kinematics at the Grand Accelerateur National d'Ions Lourds. Secondary beams of {sup 20}O at 43 MeV/A, {sup 30}S at 53 MeV/A and {sup 34}Ar at 47 MeV/A impinged on a (CH{sub 2}){sub n} target. Recoiling protons were detected in the silicon strip array MUST. Energies and angular distributions of the first 2{sup +} and 3{sup -} states were measured. A phenomenological analysis yields values of the deformation parameters {beta}{sub 2} and {beta}{sub 3} of 0.55 (6) and 0.35 (5) for {sup 20}O, 0.32 (3) and 0.22 (4) for {sup 30}S, 0.27 (2) and 0.39 (3) for {sup 34}Ar, respectively, and allows the extraction of the ratio of neutron to proton transition matrix elements (M{sub n}/M{sub p})/(N/Z) for 2{sup +} states: 2.35 (37) for {sup 20}O, 0.93 (20) for {sup 30}S and 1.35 (28) for {sup 34}Ar. Therefore the proton rich nuclei {sup 30}S and {sup 34}Ar show a 2{sup +} excitation of isoscalar character whereas the excitation of {sup 20}O is of isovector character. In order to perform a microscopic analysis of the data, we have developed a QRPA model, using three Skyrme interaction: SIII, SG2, SLy4. This model reproduces measured B(EL) values for the oxygen, sulfur and argon isotopic chains, whereas RPA calculations, which do not take pairing into account, underestimate these values. In the case of the QRPA model the energies of the first 2{sup +} state are overestimated by about 1 MeV, but the evolution along the isotopic chains is well reproduced. (M{sub n}/M{sub p})/(N/Z) ratios for the first 2{sup +} state deduced from the microscopic analysis using QRPA are 1.98 for {sup 20}O, 1.05 for {sup 30}S and 1.00 for {sup 34}Ar, in agreement with the conclusions of the phenomenological analysis. However important discrepancies are observed between the two types of analysis for other isotopes, in particular neutron rich argon and sulfur nuclei. (author)

  9. An experimental study on mineral sequestration of CO{sub 2} in basics and ultra basics rocks; Etude experimentale des reactions de carbonatation minerale du CO{sub 2} dans les roches basiques et ultrabasiques

    Energy Technology Data Exchange (ETDEWEB)

    Dufaud, F

    2006-11-15

    The first part of the thesis is dedicated to dissolution data of siderite FeCO{sub 3} and magnetite Fe{sub 3}O{sub 4} which have been monitored in situ on the FAME beamline of the european synchrotron radiation facility in Grenoble. Iron in solution close to siderite single crystals is shown to be divalent hydrated. The small size of the experimentally investigated volume of solution (200 *400 micrometer and 3 mm height) allowed to work with single crystals in well defined geometries. No specific interaction was observed between iron (II) and dissolved inorganic carbon, suggesting that modelling siderite evolution under high CO{sub 2} pressures by using CO{sub 2}-less very acidic (pH 1-2) solutions is adequate. Using initial reaction rates, we get an activation energy for siderite dissolution of 62 kJ.mol{sup -1}, consistent with existing literature data. Such a value is suggestive of a mineral/solution interface mechanism.. Data from this study and from literature are consistent over a temperature range 25 C - 125 C and a pH range pH 1-7 with an empirical law: pk = pH + E{sub a}/(ln(10)*RT(K)) - log(S/V) - 10,5 where E{sub a} = 62 kJ.mol{sup -1} and S/V is the ratio between solid surface S and fluid volume V. A value of activation energy of 73.5 kJ.mol{sup -1} is obtained in the case of magnetite, also consistent with mineral/solution processes. The second and major part of the thesis work is the realization of analogical experiments for simulating carbonation of basic and ultra basic minerals. Experiments were carried out on consolidated rock cores at 90 C and 280 bar of CO{sub 2} (low temperature experiments) and on powders contained in metallic capsules at 400-500 C and 1000-1700 bars of CO{sub 2} (high temperature experiments). The rate of mineral storage of CO{sub 2} was defined as the molar ratio of solid carbonate formed over total CO{sub 2} injected. It is of about 1% in three months in low temperature experiments whereas it reaches several tens of percents per hour in high temperature experiments. In all cases, carbonation is shown to proceed according to dissolution/precipitation mechanisms. A quasi stoichiometric coupling is evidenced between carbonation and (proto) serpentinization in high-temperature experiments. Newly formed carbonates are mostly magnesite MgCO{sub 3} with Fe and Ca in solid solution. In low temperature samples, the silicates are covered with a thin silica layer and with carbonate spherules consisting of ankerite CaFe(CO{sub 3}){sub 2} - dolomite CaMg(CO{sub 3}){sub 2} - siderite cores surrounded by magnesite overgrowth. In CO{sub 2}-saturated water, peridotites are more reactive than serpentinite and basalts, in accordance with thermodynamic modelling whereas serpentinites are the most reactive in the supercritical CO{sub 2} phase, showing stronger reactivities in this latter phase than in CO{sub 2}-saturated water. In high temperature experiments, the rate of mineral storage is larger at 400 C than at 500 C, in agreement with thermodynamic modelling of the system. High water fugacities and high fluid salinities are shown to have a positive effect on mineral storage rates. Isotopic mass balance of carbon have evidenced that about 15% of the mineral storage consist of a reduced carbon phase, also identified by transmission electron microscopy as an ill-organized graphite phase. (author)

  10. Experimental and numerical study of the strong interaction between wakes of cylindrical obstacles; Etude experimentale et numerique de l'interaction forte entre sillages d'obstacles cylindriques

    Energy Technology Data Exchange (ETDEWEB)

    Brun, Ch

    1998-04-02

    In the context of thermal-hydraulics of nuclear reactors, strong interaction between wakes is encountered in the bottom of reactor vessels where control and measurement rods of variable size and disposition interact with the overall wakes generated in these flow zones. This study deals with the strong interaction between two wakes developed downstream of two parallel cylinders with a small spacing. The analysis focusses on the effect of the Reynolds regime which controls the equilibrium between the inertia and viscosity forces of the fluid and influences the large scale behaviour of the flow with the development of hydrodynamic instabilities and turbulence. The document is organized as follows: the characteristic phenomena of wakes formation downstream of cylindrical obstacles are recalled in the first chapter (single cylinder, interaction between two tubes, case of a bundle of tubes perpendicular to the flow). The experimental setup (hydraulic loop, velocity and pressure measurement instrumentation) and the statistical procedures applied to the signals measured are detailed in chapters 2 and 3. Chapter 4 is devoted to the experimental study of the strong interaction between two tubes. Laser Doppler velocity measurements in the wakes close to cylinders and pressure measurements performed on tube walls are reported in this chapter. In chapter 5, a 2-D numerical simulation of two typical cases of interaction (Re = 1000 and Re = 5000) is performed. In the last chapter, a more complex application of strong interactions inside and downstream of a bunch of staggered tubes is analyzed experimentally for equivalent Reynolds regimes. (J.S.)

  11. Experimental study of a separated jets burner: application to the natural gas-pure oxygen combustion; Etude experimentale du comportement de bruleurs a jets separes: application a la combustion gaz naturel-oxygene pur

    Energy Technology Data Exchange (ETDEWEB)

    Salentey, L.

    2002-04-15

    The evolution of pollution standards and the optimisation of furnaces performances require a development of new burner generation and also the improvement of combustion techniques. Actually, the use of oxy-combustion in separated jets burners offers interesting prospects for NO{sub x} emission reduction and on the modularity of flames properties (lift off, flame front topology, flame length). The complex geometry of those burners leads to several problems like the three-dimensional character of the flow, which may sometimes disturb the flame stability as flames are lifted above the burner. This experimental study deals with a simplified version of that kind of burner constituted with a central natural gas jet surrounded by two oxygen jets. Primary, the study of non-reactive jet was planned in order to understand dynamic and mixture phenomena involved between jets and to provide a database useful for the computer code validation. The reactive flow developed in a furnace, which simulates the real conditions, had been characterised. The studies of the dynamic field using Laser Doppler Velocimetry (LDV) and of the turbulent mixture by conditional Laser tomography were supplemented in combustion by the visualisation of the spontaneous emission of radical OH, in the initial and final zone of the oxy-flames, like by the measurement of pollutants like NO{sub x} and soot. The measurements carried out while varying speeds of injection as well as the gap between the jets made possible the highlight of the influence of these parameters upon the stabilisation of the oxy-flames as well as the modification of the topology and the characteristics of the flows. The comparison of the measurements made in non-reactive and reactive flow shows the influence of oxy-combustion on the dynamic and scalar development of the flow for this type of burners. (author)

  12. 116 Etude du régime alimentaire de la Chouette effraie Tyto alba ...

    African Journals Online (AJOL)

    SWEET

    Abdeslam RIHANE et al. Etude du régime alimentaire de la Chouette effraie Tyto alba. (Strigiforme,Tytonidae) dans la région de Lalla Mimouna dans la plaine du Gharb, plaine du Maroc atlantique. Abdeslam RIHANE1, Said LAHROUZ2 et Rhimou EL HAMOUMI3. 1Département des Sciences de la Vie et de la Terre, ...

  13. Etude morphologique d'un cas de femme XY avec dysgénésie ...

    African Journals Online (AJOL)

    Mots clés : Etude morphologique, femme XY, dysgénésie gonadique pure. The authors describe the morphological features of a twenty years old female, without ambiguous genitalia, presenting a 46,XY karyotype, normal female external genitalia and gonadal dysgenesis. She has an android type of morpho dysplasia and ...

  14. Gruusia loeb kokku venelaste jäetud pomme ja sõjaohvreid / Liisi Poll

    Index Scriptorium Estoniae

    Poll, Liisi, 1980-

    2008-01-01

    Vene vägede lahkumist ootavas Gruusias loetakse kokku sõjakaotusi, milleks on inimkaotused, katkenud kaubandus, purustatud infrastruktuur, mahajäetud lõhkekehad. Punase Risti hinnangust sõjapõgenike kohta. Vt. samas: Vene väed lahkuvad endiselt vaid teoreetiliselt

  15. Etude comparée des paramètres agromorphologiques de dix (10 ...

    African Journals Online (AJOL)

    Etude comparée des paramètres agromorphologiques de dix (10) variétés de patate douce ( Ipomoea batatas (L.) Lam cultivées au champ dans deux (2) conditions climatiques au Tchad et au Burkina Faso.

  16. Etude des phytostérols et des acides gras de pistachia atlantica ...

    African Journals Online (AJOL)

    AKA Boko

    Afrique SCIENCE 03(3) (2007) 405 - 412. ISSN 1813-548X. Bachir Raho GHALEM et Hachemi BENHASSAINI. 405. Etude des phytostérols et des acides gras de pistachia atlantica. Bachir Raho GHALEM1 et Hachemi BENHASSAINI2. 1 Biology institute, University center Mustapha Stambouli of Mascara, 29000, Algeria.

  17. Etude linguistique chez les Baráshi/Banyaambo du Rwanda

    African Journals Online (AJOL)

    User

    Hakizimana, P., 1981, Etude d'un argot du Rwanda: urucuzi, mémoire de licence, UNR, Butare, 149 p. Hubbard, K., 1995a, "Prenasalised consonants" and cyllable timing : evidence from Runyambo and Luganda", Phonology, 12, p. 235-256. Katoke, I. K., 1975, The Karagwe Kingdom : a history of the Abanyambo of.

  18. Etude de la pollution des eaux des oueds Seybouse et Mellah ...

    African Journals Online (AJOL)

    Resume. L'objet de cette etude est d'experimenter un protocole de travail base sur des prelevements de surface et de puits de particuliers en vue d'etablir la qualite des eaux et d'assoir des bases de donnees relatives a la pollution hydrique en Algerie. Les resultats des analyses chimiques montrent pour les deux oueds un ...

  19. Estadísticos poblacionales de Triatoma sordida Stäl 1859 (Hemiptera : Reduviidae en condiciones experimentales

    Directory of Open Access Journals (Sweden)

    Oscherov Elena B.

    1996-01-01

    Full Text Available Se realizó el seguimiento longitudinal de cuatro cohortes de 100 huevos cada una. Los insectos fueron criados a 28°C ± 3°C y 63 % ± 10% de humedad relativa, y alimentados cada siete días sobre gallina (Gallus domesticus, durante 40 min. Las cohortes fueron controladas una vez por semana. Se observó un valor constante de supervivencia en las cuatro cohortes, sin picos importantes. La expectativa de vida de los machos, en promedio, fue de 37,4 semanas y la de las hembras 36,8. El tiempo generacional demandó 61,7 semanas. La tasa reproductiva neta indica que esta población se incrementará 143,3 veces con cada generación. La tasa intrínseca de crecimiento natural fue de 0,082 por semana. El máximo valor reproductivo se verificó, en promedio, a la tercer semana del ingreso al estado adulto. La distribución estable de edades de T. sordida sería de 32% huevos, 26% ninfas de primer estadio, 19% ninfas de segundo estadio, 13% ninfas de tercer estadio, 6% ninfas de cuarto estadio, 3% ninfas de quinto estadio y 1% de adultos. Es la primera cita para Argentina sobre la tabla de vida de T. sordida. El análisis de estos parámetros permite considerar que esta especie se comporta como "K estratega", en condiciones experimentales.

  20. COMPLIANCE OF KÖHLER OP:33 NO I-II-III ETUDE BOOKS THAT ARE USED IN HIGH SCHOOLS OF FINE ARTS WITH FLUTE CONCERTOS

    Directory of Open Access Journals (Sweden)

    Yucan EKE

    2015-09-01

    Full Text Available This research is done for attesting the compliance of the etudes in German composer Ernesto Köhler’s op:33 no I-II-III books that are used in high schools of fine arts, with ability to play the flute concertos in high schools of fine arts 12 grade program, in terms of the knowledge – skills and musical functions they cover and also for contributing to learning by matching the etudes and works which are relevant. Etudes and the chosen concertos are analyzed and separated into templates in terms of melody, rhythm and tone for this research. Opinions are taken from the flute lesson instructors of various universities of Turkey to define the melody, technique and rhythm patterns. As a result of the analysis, Köhler op: 33, Book I, Etudes: 2,3,6,7,8,9,10,11,12; Köhler op: 33, Book II, Etudes:1,3,4,5,8,9,10,11; Köhler op: 33, Book III, Etudes: 1, 2, 4, 5, 6, 8; It is determined that the etudes given above in Köhler books are qualified enough to be preparative and instructive for the ability of playing the flute concertos. Some suggestions are given about which etude(s is instructive for which concerto and what kind of benefits could be gained, by this study. Based on the observed results, various suggestions are made about defining and studying the etudes which meet the technical, rhythmic and melodic features of the target concerto.

  1. Simulación de una Torre de Enfriamiento Mecánica Comparada con Curvas Experimentales Simulation of a Mechanical Cooling Tower Compared with Experimental Curves

    OpenAIRE

    Jader D Alean; Gail A Gutiérrez; Farid Chejne; Marlon J. Bastidas

    2009-01-01

    El objetivo del trabajo es modelar y simular una torre de enfriamiento mecánica forzada a escala piloto. Las variables físicas se correlacionaron a partir de la transferencia de calor y materia y los resultados de la simulación son analizados mediante graficas que muestran la variación de la humedad, flujo de agua, calor latente, calor sensible, calor total, temperatura del agua y del aire. El coeficiente de transferencia de materia se obtuvo a partir de los datos experimentales y la solución...

  2. Modelización del sistema de almacenamietno de energía y de su regulador de un vehículo solar de fines experimentales

    OpenAIRE

    Mendoza Zaplana, Sergio

    2015-01-01

    En este proyecto, se pretende modelizar con el programa ‘Matlab-Simulink’ un sistema de acumulación y regulación para un vehículo solar de fines experimentales. Compuesto este por un motor de corriente continua de imanes permanentes de características similares a las que presenta el prototipo del vehículo Aníbal, desarrollado por el Departamento de Ingeniería Eléctrica de la Universidad Politécnica de Cartagena. Con el objetivo de modelizar un sistema de acumulación y regulación además de ave...

  3. Cómo trabajar las ciencias experimentales a través del método Doman y las inteligencias múltiples

    OpenAIRE

    Ontoria González, Laura

    2015-01-01

    El proyecto que se presenta a continuación consiste en una propuesta didáctica innovadora relacionada con las ciencias experimentales en el aula de Infantil a través del método Doman y las Inteligencias Múltiples. El empleo de estas metodologías de manera conjunta se apoya y justifica de manera teórica y práctica. La propuesta didáctica se llevó a cabo en un centro escolar en el nivel de cuatro años, concretamente con veinticinco alumnos, con resultados muy positivos.

  4. Efecto de la ración alimenticia en el crecimiento de juveniles de tilapia Oreochromis aureus (Steindachner) bajo condiciones experimentales de cultivo

    OpenAIRE

    M. García-Ulloa

    2004-01-01

    Se evaluó el crecimiento de juveniles (2.77 g de peso promedio) de la tilapia Oreochromis aureus (Steindachner), cultivados con diferentes raciones alimenticias bajo condiciones experimentales de laboratorio. Los tratamientos consistieron en el suplemento alimenticio de 6, 8 y 10% del peso de la biomasa total, los cuales fueron estudiados por triplicado en peceras de vidrio de 113 L de capacidad, ajustando una densidad inicial de 25 peces por acuario. El ensayo tuvo una duración de 35 días, y...

  5. Modelos experimentales para la evaluación de la acción cicatrizante de medicamentos

    Directory of Open Access Journals (Sweden)

    Raimara González Escobar

    2002-12-01

    Full Text Available Los intentos del organismo para reparar las lesiones inducidas por agresiones locales comienzan muy precozmente en el proceso de la inflamación, y finalmente concluyen con la reparación y sustitución de las células lesionadas por células sanas. El proceso de cicatrización de una herida en la piel involucra la compleja interacción de muchos tipos de células y ocurre como una cascada secuencial de procesos solapados e íntimamente relacionados. Existen varios modelos farmacológicos experimentales que permiten evaluar la acción cicatrizante de un principio activo, profundizando en los eventos específicos de la cicatrización. En este trabajo se presentarán los detalles de algunos de estos modelos, los cuales son: modelo de lesión inducida por quemadura en curieles, modelo de 6 heridas asépticas en cerdos, promoción de cicatrización por segunda intención en ratas y modelo para predecir la distribución de un medicamento aplicado tópicamente en heridas. Estos ensayos permiten el estudio de múltiples elementos histológicos, bioquímicos, celulares y clínicos, característicos del proceso de cicatrización.The attempts of the organism to repair injuries induced by local aggressions begin very early in the inflammation process and conclude finally with the reparation and substitution of those cells damaged by sound cells. The healing process of a skin wound involves the complex interaction of many types of cells and a sequence of sneaky and closely related processes take place. There are various pharmacological experimental models allowing to evaluate the healing action of an active principle and to go deep into the specific healing events. Details are given in this paper about the following models: model of injury induced by burn in guinea pigs, model of 6 aseptic wounds in pigs, promotion of healing by second intention in rats and a model to predict the distribution of a drug topically applied in wounds. These assays make possible

  6. Programa de viviendas experimentales en Móstoles, Comunidad de Madrid. España. (Preámbulo

    Directory of Open Access Journals (Sweden)

    Abad Carrascosa, Manuel

    1990-04-01

    Full Text Available This program consists of a total of 102 houses. They are situated in one of the housing estates in the General Urbanization Plan of the Móstoles Town Council (Town on outskirts of Madrid. The development of the prototypes of three different types of housing is to be studied with the aim of studying the experimental results of each one: — Progressive housing. — Housing with passive solar energy — Housing constructed on a basis of a special system in series. The three have the common aim of achieving finanical saving, but by different means: initial investment, saving in energy expenditure, the constructive system. The group of houses is about to be delivered into the hands of its users. We regret the incompleteness of the Information due to the lack of the most important results; the derivatives of its use and development, and Information of a social, economic, cultural, etc., character.

    Esta actuación consta de un total de 102 viviendas. Se encuentran localizadas en uno de los polígonos del Plan General de Urbanismo del Ayuntamiento de Móstoles (Población del extrarradio de Madrid. Se plantea el estudio y desarrollo, por separado, de tres prototipos diferentes de vivienda con el fin de poder estudiar los resultados experimentales de cada uno: — Viviendas progresivas. — Viviendas con energía solar pasiva. — Viviendas construidas a base de un sistema especial en serie. Los tres plantean el ahorro económico como fin común, pero desde distintas bases de partida: la inversión inicial; el ahorro energético, y el sistema constructivo. El conjunto se encuentra a punto de ser entregado a sus usuarios. Lamentamos lo incompleto de la información debido a la falta de sus resultados más importantes: los derivados de su uso y desarrollo; sociales, económicos, culturales, etcétera.

  7. Proceso de gasificación de biomasa: una revisión de estudios teórico- experimentales

    Directory of Open Access Journals (Sweden)

    Juan Pérez

    2010-01-01

    Full Text Available La situación energética y medioambiental mundial hace que la generación de energía mediante sistemas basados en energías renovables tome cada vez una mayor relevancia. Estos sistemas tienen una doble ventaja ya que posibilitan la diversificación energética y reducen la dependencia del petróleo a la vez que se disminuyen las emisiones globales de CO2. La biomasa es uno de los recursos energéticos con mayor potencial tanto en países desarrollados como emergentes pero sigue sin sufrir el desarrollo esperado. La gasificación de biomasa es uno de los sistemas con gran potencial ya que permite la generación tanto de energía térmica como eléctrica, mediante tecnologías de bajo costo como los gasificadores de lecho fijo (potencias medias- bajas, o reactores de lecho fluidizado con tecnología más exigente y con mayor capacidad de generación. La transformación de la biomasa en un combustible gaseoso, aprovechable en motores de combustión interna alternativos o en turbinas de gas como combustible, exige que la biomasa atraviese varios procesos termoquímicos, compuestos por reacciones endotérmicas (secado, devolatilización y reducción y exotérmicas (oxidación de volátiles y carbón. La selección de un gasificador requiere conocer las propiedades de la biomasa, mientras que el diseño del mismo exige conocer el fenómeno termoquímico por completo. El objetivo de este trabajo es presentar una revisión actualizada de los diferentes planteamientos tanto teóricos como experimentales desarrollados para estudiar el proceso de gasificación de biomasa, tanto en lecho fijo como en lecho fluidizado, con miras a diseñar gasificadores de biomasa.

  8. Etude sur les tendons en materiaux composites et leur application aux ancrages postcontraints

    Science.gov (United States)

    Chennouf, Adil

    L'objectif general de la presente these est d'evaluer le comportement a l'arrachement et au fluage d'ancrages injectes constitues de tendons en materiaux composites afin d'etablir des recommandations plus appropriees et realistes pour le dimensionnement et la conception. Quatre types de tendons en materiaux composites, deux a base de fibres d'aramide et deux a base de fibres de carbone, ont ete utilises dans l'etude. Les travaux de recherche de cette these ont porte notamment sur: (I) Une caracterisation physique et mecanique des tendons en materiaux composites utilises dans l'etude. (II) Une etude en laboratoire sur les coulis de scellement. La premiere etape de cette etude a concerne le developpement d'un coulis de scellement performant adapte aux tendons en materiaux composites et a differentes situations d'injection. La seconde etape a traite des essais de caracterisations physique et mecanique du coulis de scellement developpe comparativement a trois coulis de scellement usuels d'un meme rapport E/L de 0,4. (III) Une etude sur des modeles reduits d'ancrages injectes. (IV) Une etude sur des modeles d'ancrages a grande echelle. La synthese de ces etudes a permis d'enoncer les principales conclusions suivantes: (1) Les valeurs moyennes des charges de rupture des tendons en materiaux composites ont ete de 1% a 29% superieures a celles specifiees par les manufacturiers. (2) L'etude sur les coulis de scellement a permis le developpement de coulis de ciment repondant aux criteres fixes, soient une grande stabilite, une bonne fluidite, une legere expansion et de bonnes caracteristiques mecaniques. (3) Les tendons en materiaux composites ont montre des contraintes d'adherence maximum superieures a celles des tendons en acier. (4) Le type de fibre, la configuration et le fini de surface des tendons en materiaux composites gouvernent leur resistance a l'adherence. (5) L'introduction de sable et d'autres ajouts comme les fines de silice et la poudre d'aluminium au coulis

  9. Expériences scolaires au Congo Belge. Etude exploratoire | Vinck ...

    African Journals Online (AJOL)

    Expériences scolaires au Congo Belge. Etude exploratoire. H Vinck, J Briffaerts, F Herman, M Depaepe. Abstract. Résumé Sur base de huit interviews d'anciens élèves de l'enseignement colonial au Congo belge, cette étude explore les effets que les processus pédagogiques coloniaux ont eu sur les élèves. Mots-clés: ...

  10. Etude ethnobotanique, évaluation in vitro de l'activité antifongique et ...

    African Journals Online (AJOL)

    Etude ethnobotanique, évaluation in vitro de l'activité antifongique et cytotoxique des extraits de Enantia polycarpa (DC) Engl. et Diels (Annonaceae) ... humaines à des concentrations de 125 à 1000 μg/ml, suggérant ainsi la prise de précaution quant à l'emploi de cette substance végétale dans le traitement traditionnel.

  11. Etude ethnobotanique des plantes alimentaires utilisées en période ...

    African Journals Online (AJOL)

    Etude ethnobotanique des plantes alimentaires utilisées en période de soudure dans les régions Sud du Mali. ... Parkia biglobosa, Adansonia digitata et Vitellaria paradoxa sont les plantes les plus utilisées soit seules ou dans des plats comme additifs. Certaines de ces plantes servent également comme médicament et ...

  12. Etude de l'activité antihypertensive d'une association de plantes ...

    African Journals Online (AJOL)

    Etude de l'activité antihypertensive d'une association de plantes (Schrankia leptocarpa, Garcinia kola et Ocimum americanum) chez le rat Wistar. ... de plantes étudiée a un effet positif sur l'HTA induite et les résultats semblent indiquer son innocuité. Mots clés : Pression artérielle, plantes médicinales, hypotenseur, toxicité.

  13. El AMMI y cluster en la selección de los mejores híbridos experimentales de maíz

    Directory of Open Access Journals (Sweden)

    Guillermo Casta\\u00F1\\u00F3n

    2000-01-01

    Full Text Available El AMMI y Cluster en la selección de los mejores híbridos experimentales de maiz. En un experimento de maíz repetido en cuatro ambientes, se aplicó el análisis de efectos principales aditivos e interacción multiplicativa (AMMI y el de taxonomía numérica o cluster, para estudiar si la estabilidad del rendimiento de grano (RG de los híbridos ensayados se asociaba con el agrupamiento de los híbridos hecho por el cluster. Las variables que tuvieron más peso en el agrupamiento fueron el RG, altura de la planta (AP,altura de mazorca ( AM y mazorca por planta (PRO, principalmente. De lo encontrado en este trabajo se puede establecer que el AMMI es efectivo en la estimación de la estabilidad de los híbridos experimentales evaluados y que junto con el cluster, pueden ser dos herramientas útiles para hacer una buena selección de material experimental con mayores posibilidades de éxito

  14. Experimental techniques; Techniques experimentales

    Energy Technology Data Exchange (ETDEWEB)

    Roussel-Chomaz, P. [GANIL CNRS/IN2P3, CEA/DSM, 14 - Caen (France)

    2007-07-01

    This lecture presents the experimental techniques, developed in the last 10 or 15 years, in order to perform a new class of experiments with exotic nuclei, where the reactions induced by these nuclei allow to get information on their structure. A brief review of the secondary beams production methods will be given, with some examples of facilities in operation or under project. The important developments performed recently on cryogenic targets will be presented. The different detection systems will be reviewed, both the beam detectors before the targets, and the many kind of detectors necessary to detect all outgoing particles after the reaction: magnetic spectrometer for the heavy fragment, detection systems for the target recoil nucleus, {gamma} detectors. Finally, several typical examples of experiments will be detailed, in order to illustrate the use of each detector either alone, or in coincidence with others. (author)

  15. Contribution to the study of the interaction of slow neutrons with {sup 235}U using the time-of-flight method; Contribution a l'etude par la methode du temps de vol de l'interaction de neutrons lents avec l'U{sup 235}

    Energy Technology Data Exchange (ETDEWEB)

    Michaudon, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-05-15

    This study concerns the properties of the excited levels of uranium 236 obtained by interaction of slow neutron with uranium 235. The experiments have been carried out at the Saclay linear electron accelerator by use of the time of flight method. In the first part of this paper, we examine the technical and physical conditions which rule the experiments: compromise between resolution and counting rate, time dispersion due to the slowing down of the neutrons and crystalline binding effects. In a second part the experimental results i.e. total, fission and ternary fission cross sections are given. The third part deals with the analysis of these results: the resonance parameters determination ({tau}{sub n}, {tau}{sub {gamma}}, {tau}{sub f}), the study of their statistical distribution and of their correlations. We tried some classifications of the resonances according to their parameters and compared these classifications to each other and to other results. At least the evidence of a cross section correlation with a range smaller than 100 eV seems to be confirmed. (author) [French] Cette etude porte sur les proprietes des niveaux excites de l'Uranium-236 obtenus par l'interaction de neutrons lents avec le {sup 235}U. La technique experimentale est celle de la spectrometrie par temps de vol, les experiences ayant ete realisees aupres de l'accelerateur lineaire d'electrons de Saclay, Dans une premiere partie nous examinons les donnees techniques et physiques conditionnant les experiences: compromis entre resolution et taux de comptage, dispersion en temps due au ralentissement des neutrons, effet des liaisons cristallines. Dans une deuxieme partie sont exposes les resultats experimentaux: sections efficaces totales, de fission et de fission ternaire du {sup 235}U. Une troisieme partie porte sur l'analyse de ces resultats: determination des parametres ({tau}{sub n}, {tau}{sub {gamma}}, {tau}{sub f}), etude de leurs distributions statistiques et

  16. The study by means of a photomultiplier of the scintillations produced by {alpha} particles striking a zinc sulphide screen; Etude, au photomultiplicateur, des scintillations produites par les particules {alpha} dans un ecran de sulfure de zinc. Application a la numeration precise des particules {alpha}

    Energy Technology Data Exchange (ETDEWEB)

    Anthony, J.P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-06-15

    The object of the study is the accurate counting of {alpha} particles by p-m. detection of their scintillations upon impact with a zinc sulphide screen. The main advantage of the method is the extreme simplicity of the electronics used: the possibility of obtaining a utilizable pulse from the p-m. (EMI5311) without any amplification, and in linear response, is demonstrated. The scintillation produced by an impact on Zn-S has also been studied experimentally. The decrease of light intensity in relation to time may be interpreted by the exponential relation: I = I{sub 0} exp (-t / {tau}) whereby {tau} = (39 {+-} 0,1) 10{sup -6} s. The relation between scintillation intensity and remaining trajectory after travel through a given air-space has also been determined. Possible suitable applications of this method of {alpha} counting are those where good stability and low background are necessary. Results stated bear on air contamination studies, isotopic composition variation measurement of uranium, bismuth content measurement in alloys by irradiation of specimens in a thermal neutron flux and {alpha} count on the Po formed. (author) [French] Ce travail est consacre a l'etude de la numeration precise des particules {alpha} par detection au photomultiplicateur des scintillations produites par ces particules dans un ecran de sulfure de zinc. Le principal avantage de cette methode reside dans l'extreme simplicite de l'appareillage electronique; il est en effet montre qu'il est possible, tout en convoyant une reponse lineaire, d'obtenir du photomultiplicateur (EMI5311) un signal electrique utilisable sans aucune amplification. La scintillation produite par l'impact des particules {alpha} sur un ecran de Zn-S est etudiee experimentalement. La decroissance de l'intensite lumineuse en fonction du temps est interpretable par la relation exponentielle I = I{sub 0} exp (-t / {tau}) avec {tau} = (39 {+-} 0,1) 10{sup -6} s. La relation entre l

  17. Development of a semiconductor counter telescope with low background for the investigations of charged particles produced in reactions induced by neutrons; Realisation et mise au point d'un telescope a semi-conducteurs et a faible bruit-de-fond pour l'etude des reactions neutronsparticules chargees

    Energy Technology Data Exchange (ETDEWEB)

    Helleboid, J.M. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-08-15

    A AE-E counter telescope for charged particles (p, d, t) produced in reactions with neutrons has been constructed. The semiconductor counter telescope method allows the investigations of two and three-body reactions {sup 6}Li(n,p), D(n,np)n induced by 14 MeV neutrons. By using a coincidence of associated alpha particle pulses with those ({delta}E,E) in the telescope, the background is considerably reduced for all angles outside the coincidence cone, i.e. larger than 15 deg. (L). For forward angles, the same telescope ({delta}E{sub 2}/E) plus a thin semiconductor ({delta}E{sub 1}) allows keeping a low background. The multiparameter analysing method ({delta}E{sub 1}, {delta}E{sub 2}, E) from the experimental range-energy data gives a linearity, an efficiency and an identifying power which are satisfactory. The identification is performed by differed time on a IBM 7044 computer. (author) [French] On a realise un spectrometre de particules chargees (p, d, t) avec identification des particules, pour l'etude des reactions neutrons-particules chargees. La methode du telescope a semi-conducteurs permet d'effectuer l'etude de reactions a deux corps [{sup 6}Li(n,p)] et de reactions a trois corps [D(n,pn)n] a 14 MeV. L'utilisation de la particule alpha associee en coincidence avec les impulsions ({delta}E,E) du telescope permet d'obtenir un bruit-de-fond tres faible pour tous les angles situes en dehors du cone de coincidence, c'est-a-dire superieurs a {approx_equal} 15 deg. (L). Pour les angles avant, le meme telescope ({delta}E{sub 2}/E) plus un semi-conducteur mince ({delta}E{sub 1}) permet de conserver un faible bruit-de-fond. La methode d'analyse multiparametrique ({delta}E{sub 1}, {delta}E{sub 2}, E) a partir des donnees experimentales parcours-energie, donne une linearite, une efficacite et un pouvoir d'identification satisfaisants. L'identification est effectuee en temps differe sur un calculateur numerique IBM 7044

  18. Some experiments on the high-low transition of quartz; Recherches experimentales sur une transformation du quartz

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1959-12-15

    , nous avons rassemble un grand nombre de resultats numeriques relatifs aux proprietes elastiques, piezoelectriques et optiques du quartz. Certains ont ete collectes dans la litterature; d'autres ont ete obtenus par nous a l'aide de methodes experimentales que nous decrivons, de facon a pouvoir presenter un tableau complet de l'evolution de ces constantes dans un domaine de temperature entourant largement le point de transformation {alpha} - {beta} situe a 574 deg. C. De nouveaux phenomenes ont ete observes au cours de ces mesures. Dans la troisieme partie, nous montrons qu'une meme fonction de la temperature decrit l'evolution de la constante piezoelectrique et de la constante elastique qui s'annulent en phase {beta}. Une seule autre fonction suffit a decrire correctement l'evolution de toutes les autres constantes etudiees, depuis leur valeur en phase {alpha} jusqu'a leur valeur en phase {beta}. A l'aide d'hypotheses sur la nature de l'entropie de transformation, nous essayons enfin d'expliquer la forme de ces fonctions. (auteur)

  19. ENFERMEDAD DE HUNTINGTON: MODELOS EXPERIMENTALES Y PERSPECTIVAS TERAPÉUTICAS Huntington'disease: Experimentals Models and Therapeutic Perspectives

    Directory of Open Access Journals (Sweden)

    TERESA SERRANO SÁNCHEZ

    Full Text Available La enfermedad de Huntington (EH es un trastorno degenerativo de Weiss de origen hereditario. Hasta el momento no existe un tratamiento efectivo para la enfermedad que inexorablemente después de transcurridos 15 a 20 años, evoluciona hacia incapacidad total o muerte. En este trabajo se revisan las características clínicas y morfológicas de la EH y los modelos experimentales más utilizados para su estudio tomando como fuente, artículos indexados en la base de datos Medline publicados en los últimos 20 años. Se valoran las ventajas y desventajas de estos modelos y su perspectiva para el desarrollo de ensayos clínicos. El consenso de lo reportado plantea que de los modelos tóxicos, los inducidos por neurotoxinas tales como ácido quinolínico parecen ser los más adecuados para reproducir las características neuropatológicas, y por otro lado los modelos genéticos contribuyen con más evidencias al conocimiento del origen etiológico de la enfermedad. Numerosos tratamientos han sido aplicados en el manejo de las manifestaciones clínicas que aparecen en EH, sin poder detener o disminuir las afectaciones que derivan de la pérdida neuronal. La sintomatología clínica ha sido posible reproducirla, al menos en parte, en animales de experimentación lo que ha permitido realizar ensayos terapéuticos. Desde el punto de vista de tratamiento, lo que más promisorio parece ser, la terapia celular con células provenientes de diferentes fuentes y dentro de ellas las no neurales, que implican menor censura ética y mayor factibilidad de obtención para la aplicación en los enfermos. Por otro lado el desarrollo de la tecnología del ARN de interferencia, emerge como una herramienta terapéutica potencial para el tratamiento de EH, así como para responder interrogantes básicas relacionadas con el desarrollo de la enfermedad.Huntington'disease (HD is a degenerative dysfunction of hereditary origin. Up to date there is not, an effective treatment

  20. Experimental study of the test module of the electromagnetic end-cap calorimeter for the ATLAS experiment. Study of the spin correlation in the production of pairs tt-bar; Etude experimentale des performances du module 0 du calorimetre electromagnetique bouchon d'ATLAS. Etude de la correlation de spin dans la production des paires tt-bar au LHC

    Energy Technology Data Exchange (ETDEWEB)

    Hinz, L

    2001-06-01

    LHC, the future CERN proton collider, will start in 2006. It will be devoted to a better understanding of the Standard Model and new physics research. With a 10 {integral}b{sup -1} per year at low luminosity during the first three years, then 100 {integral}b{sup -1} per year, and energy of 14 TeV in the center of mass, the LHC is designed to discover the Standard or SUSY Higgs boson, or probe signature of new physics. ATLAS, one of the four experiments at the LHC, can study a large physics range, as Higgs boson, top and bottom, gauge bosons and new particles expected by SUSY model or other models beyond the Standard Model. The CPPM laboratory is responsible of a part of the electromagnetic end-cap calorimeter for the ATLAS experiment. In 1999, an ATLAS-like prototype of module was stacked in Marseille and intensively tested at CERN. Description of the calorimeter and a part of test-beam results are presented in this PhD manuscript. In parallel, a study about potentiality of the tt-bar spin correlation measurement was done. The high tt-bar statistic produced at the LHC allows to explore the quark top properties in details and being sensitive to new physics phenomena. Signatures of such physics can be extracted from tt-bar decay product angular distributions which are sensitive to tt-bar spin correlation. (authors)

  1. Avances en investigación de la discapacidad intelectual de origen genético: tratamientos experimentales en el síndrome X frágil

    Directory of Open Access Journals (Sweden)

    Yolanda de Diego Otero

    2017-06-01

    Full Text Available De Diego Otero, Y. et al. (2017: “Avances en investigación de la discapacidad intelectual de origen genético: tratamientos experimentales en el síndrome X frágil”. Revista Española de Discapacidad, 5 (I: 217-227.

  2. ‘¿A qué sabe la luna?’ : un proyecto para aprender ciencias experimentales en Educación Infantil

    OpenAIRE

    Jiménez Martín, Cristina

    2015-01-01

    El principal objetivo de este trabajo es acercar al aula de Educación Infantil las ciencias experimentales a partir de la metodología por proyectos y teniendo como temática la luna. Este proyecto está dirigido al primer curso del segundo ciclo de la etapa de Educación Infantil, es decir, edades comprendidas entre los 3 y los 4 años. En este trabajo se expondrán las ideas principales de algunos de los autores más relevantes en educación, así como la metodología que se llevará a cabo, l...

  3. El rol de los valores numéricos de las medidas experimentales en el aprendizaje por indagación

    Directory of Open Access Journals (Sweden)

    Javier ARLEGUI DE PABLOS

    2010-01-01

    Full Text Available El aprendizaje por indagación en ciencias experimentales se entiende como un aprendizaje de resolución de problemas basado en la construcción y uso de modelos, y tiene actualmente su modelización didáctica en la teoría de las organizaciones praxeológicas. En este marco, los valores numéricos de las medidas juegan un papel preciso y de suma importancia; actúan como herramienta (útil en la construcción semántica de las magnitudes del fenómeno, y como objeto de conocimiento en el proceso de modelización de dicho fenómeno. Se muestra esta doble función en el caso de la elasticidad de un resorte.

  4. Study of acid-base properties in various water-salt and water-organic solvent mixtures; Etude de proprietes acides-bases dans divers melanges eau-sels et eau-solvants organiques

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, M. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-02-01

    , nous avons compare les constantes d'equilibre du type HB{sup +} {r_reversible} H{sup +} + B et HA {r_reversible} H{sup +} + A determinees experimentalement avec celles que l'on peut calculer a l'aide des relations acquises dans la premiere partie de cette etude et interprete de facon simple la forme des courbes representatives des fonctions d'acidite de Hammett Ho. (auteurs)

  5. Contribution to thermodynamics and kinetics of argon, krypton and xenon at very low temperatures; Contribution a l'etude thermodynamique et cinetique de l'argon, du krypton et du xenon aux tres basses temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Levenson, L.L. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    A critical analysis of the main theories of condensation, which are due to Zwanzig, Cabrera, Mc Caroll and Ehrlich, Wanlass, Armand, and Yu and Soo, is made. A condensation coefficient equal to unity is expected from these theories, except Armand and Yu and Soo, when the temperature of the gas impinging on its own solid phase is equal or less than 300 K. Using a resonating quartz microbalance the sensitivity of which is 10{sup -9} g. cm{sup 2} the experimental data agree with these theories when the temperature of the solid is less than 20 K. However the agreement must be interpreted for the more sophisticated theories of Armand and Yu and Soo. Regarding the sublimation of the rare gases one is faced with the theories of Salter, Eyring, Goodman and Armand. Within an order of magnitude the experimental data given here agree with the expected values. Moreover Armand theory is able to give the physical meaning of the observed results for argon sublimation from a krypton or a xenon crystalline substrate: localized modes of surface vibration occur. The relaxation time for the thermalization of the argon deposit is found greater than twelve hours at 25 K. (author) [French] Ce travail inclut l'etude critique des principales theories de la condensation dues a Zwanzig, Cabrera, Mc Caroll et Ehrlich, Wanlass, Armand, et Yu et Soo. Ces theories, sauf les deux dernieres, prevoient un coefficient de condensation egal a 1 lorsque le gaz incident sur son propre solide a une temperature inferieure ou egale a 300 K. Les mesures effectuees a l'aide d'une microbalance a quarz resonnant sensible a 10{sup -9} g. cm{sup 2} ont confirme ces theories dans le cas ou la temperature du solide est inferieure a 20 K. Cet accord doit cependant etre interprete pour les theories plus completes d'Armand d'une part, Yu et Soo d'autre part. Pour la sublimation des gaz rares on se trouve en presence des theories de Salter, Eyring, Goodman et Armand. Leurs previsions sont

  6. Study of the contamination of live-stock during periods of radio-active fall-out (1963); Essai d'etude de la contamination du cheptel en periode de retombees radioactives (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Michon, G.; Jeanmaire, L. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1963-07-01

    The authors have tried, during the radioactive period corresponding, to the nuclear tests of the autumn 1961, to follow under natural conditions the contamination of a herd of cattle made up 9 cows and 7 calves. The observations concern I{sup 131}, which was studied in particular, and the mixture of fission products. As far as the excretion of iodine in milk is concerned, the equilibrium is established slowly and the amount found in the milk is about 1 per cent of the daily intake. This figure is lower than those based on experimental studies (given in the literature). For the mixture of products, only a small number of elements is metabolised. The fraction found in 1 kilo of liver is about 5 x 10{sup -5} of the amount of Zr-Nb taker up per day, and about 4 x 10{sup -4} of the daily intake of Ru. These elements are not found afterwards in muscle. (authors) [French] Les auteurs ont tente pendant la periode de retombees consecutives aux tirs nucleaires de l'automne 1961 de suivre dans des conditions naturelles la contamination d'un troupeau de bovins constitue de 9 vaches et 7 veaux. Les observations portent sur l'{sup 131}I plus particulierement etudie et sur le melange des produits de fission. En ce qui concerne l'excretion d'iode dans le lait l'equilibre s'etablit lentement et la quantite retrouvee dans un litre est de l'ordre de 1 pour cent de la quantite ingeree journellement. Cette valeur est inferieure a celles trouvees dans la litterature et resultant d'etudes experimentales. En ce qui concerne le melange de produits un petit nombre d'elements seulement sont metabolises La fraction que l'on retrouve dans un kilo de foie est de l'ordre de 5.10{sup -5} de la quantite de Zr-Nb ingeree par jour et de l'ordre de 4.10{sup -4} de la quantite de Ru ingeree par jour. Ces elements ne se retrouvent pas dans le muscle. (auteurs)

  7. Etude de la diversité, de l'endémisme et de la distribution spatiale ...

    African Journals Online (AJOL)

    Etude de la diversité, de l'endémisme et de la distribution spatiale des Rubiaceae de Côte d'Ivoire. Fatou Nanou Tuo, Kouao Jean Koffi, Akossoua Faustine Kouassi, Moussa Kone, Bakayoko Adama, Jan Bogaert ...

  8. 107 Etude des facteurs de variation des prix d'intérêt des matières ...

    African Journals Online (AJOL)

    DELL

    1Institut National Agronomique de Tunisie, Département Ressources Animales, Halieutiques, et de. Technologie Agroalimentaire, 43 avenue Charles Nicolle 1082 Tunis Mahrajene, Tunisie. 2Laboratoire Matériaux, Molécules et Applications, Institut Préparatoire aux Etudes Scientifiques et. Techniques, BP 51 2070 La ...

  9. Contributions a L'etude de Dispositifs D'optique Integree

    Science.gov (United States)

    Touam, Tahar

    Cette these contient des contributions a l'etude de deux champs du vaste domaine de l'optique integree. A cet effet, nous avons divise notre travail en deux grandes parties:. Dans une premiere partie, nous traitons le probleme de la realisation d'une nouvelle classe de guides d'onde planaires utilisables dans le domaine de longueur d'onde de l'infrarouge moyen (infrarouge thermique), domaine ou l'apparition anticipee de fibres optiques a pertes extremement faibles rendraient fort interessante l'existence de tels guides d'onde planaires. Dans un premier temps, nous presentons une etude analytique originale d'une structure planaire a profil d'indice gradue, suivie d'une analyse d'un guide canal base sur cette structure. Dans un deuxieme temps, nous decrivons le procede de fabrication par pulverisation atomique d'un guide planaire forme d'arseniure de gallium (AsGa) sur du dioxyde de silicium (SiO_2 ), combinaison de materiau compatible avec l'infrarouge moyen. Finalement, nous presentons une etude de conception d'un reseau de surface destine a coupler la lumiere dans un tel guide, les autres methodes traditionnelles de couplage semblant peu appropriees aux environs de lambda = 10 mum. Dans une deuxieme partie, nous traitons le probleme de la jonction Y en optique integree, jonction qui soufre de pertes tres importantes des que l'angle d'ouverture devient interessant pour le concepteur de circuits integres optiques. L'analyse est basee sur la methode numerique dite BPM (Beam Propagation Method; methode de propagation du faisceau) qui fait l'objet d'un bref rappel. Nous poursuivons avec l'etude et l'optimisation d'une nouvelle jonction Y dont l'essence est l'utilisation du phenomene de diffraction a travers trois fentes de phase. Nous obtenons ainsi une tres bonne jonction, separant proprement le faisceau, a une ouverture de 10 degres. Finalement, nous faisons un rappel d'un profil d'indice dit "ideal" pour guides courbes et nous proposons l'utilisation de tels guides

  10. Bio-metric study of pig karyotype; Etude biometrique du caryotype du porc

    Energy Technology Data Exchange (ETDEWEB)

    Haag, J.; Lacourly, N.; Nizza, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    This study has a twofold purpose, the former is to determine the swine karyotype as accurately as possible, the latter is to try and develop a method of automatic classification and to show its possibilities and limits. (authors) [French] Cette etude a un double objet: d'une part, de definir de la facon aussi precise que possible le caryotype du porc et d'autre part, de tenter une methode de classification automatique et d'en montrer les possibilites ainsi que les limites. (auteurs)

  11. Mesures experimentales de l'impact des revetements hydrophobeset superhydrophobes sur la trainee et la portance d'un profil aerodynamique propre et glace

    Science.gov (United States)

    Villeneuve, Eric

    Ce projet, realise a la demande du Laboratoire International des Materiaux Antigivre, a pour but de mesurer et definir experimentalement l'impact de revetements hydrophobes sur les coefficients de trainee et de portance d'un profil NACA 0012. Pour ce faire, la balance aerodynamique du LIMA devait tout d'abord etre amelioree afin d'offrir une sensibilite suffisante pour realiser le projet. Plusieurs ameliorations ont ete faites, comme le changement des cellules de charge, la diminution du nombre de cellules de charge, le changement du cadre de la balance, etc. Une fois ces ameliorations terminees, la reproductibilite, l'exactitude et la sensibilite ont ete valides afin de s'assurer de la fiabilite des resultats offerts par la balance. Pour les angles d'attaque etudies avec les revetements, soient -6° et 0°, la balance a une reproductibilite de +/-2,06% a 360 000 de nombre de Reynolds. Pour valider la sensibilite, des essais a -6° et 0° d'angle d'attaque et des nombres de Reynolds de 360 000 et 500 000 ont ete faits avec des papiers sables. Les resultats de ces essais ont permis de, tracer des courbes de tendances du coefficient de trainee du NACA 0012 en fonction de la rugosite de surface et d'etablir la valeur de la sensibilite de la balance a +/-8 mu m. Cinq revetements populaires ont ete choisis pour l'experimentation, soient le Wearlon, le Staclean, le Hirec, le Phasebreak ainsi que le Nusil. Les revetements sont soumis aux memes conditions experimentales que les papiers sables, et une rugosite equivalente est trouvee par extrapolation des resultats. Cependant, les rugosites equivalentes de surfaces different entre -6° et 0°. Les essais avec le Staclean et le Hirec donnent des coefficients de trainee equivalent a ceux avec l'aluminium, alors que le Wearlon, le Nusil et le Phasebreak donnent une augmentation du coefficient de trainee de 13%, 17% et 25% respectivement par rapport a l'aluminium. Pour les coefficients de portance, la balance ne detecte pas l

  12. Etude des chaines de spins par les methodes de la theorie quantique des champs

    Science.gov (United States)

    Allen, Dave

    Notre etude porte sur la chaine de spins en zigzag avec dimerisation dans le cas des spins 1/2 et 1. L'echelle de spin ordinaire et la chaine en zigzag simple en sont des cas particuliers. Dans la limite continue, ces systemes sont decrits par des modeles Wess-Zumino-Witten couples. Afin de pouvoir calculer les fonctions de correlation, nous exposons differentes equivalences quantiques permettant de simplifier les calculs. Dans le cas de chaines de spin 1/2, nous demontrons l'equivalence avec un modele de type Gross-Neveu, en fonction de fermions de Majorana; ces fermions decrivent alors les excitations elementaires du systeme. Nous exposons une vision classique de ces excitations afin de voir les mecanismes de confinement des spinons. Dans le cas de chaines de spin 1, l'etude est plus complexe. Nous pouvons decrire le systeme a l'aide de modeles sine-Gordon perturbes par de nombreuses interactions. En se limitant aux plus importantes, nous pouvons expliquer le comportement du gap en fonction du couplage interchaine observe numeriquement.

  13. Gestión de Materiales Experimentales y su Uso en Replicaciones de Experimentos: Un Mapeo Sistemático de la Literatura

    Directory of Open Access Journals (Sweden)

    Edison Espinosa

    2016-11-01

    Full Text Available La Ingeniería de Software Experimental (ISE aplica la experimentación para obtener conocimiento sobre productos, métodos, técnicas usados en el proceso de desarrollo software. Para validar el conocimiento es necesario repetir el experimento original tantas veces como sea necesario. Se requieren mucha información y materiales acerca del experimento para que un experimentador realice una replicación. Previa a la ejecución de la replicación del experimento, algunos o la totalidad de los materiales pueden requerir cambios produciendo nuevas o modificadas versiones de estos. Una vez ejecutada la replicación del experimento se espera que, parte o la totalidad de los materiales, se incorporen al material del experimento original. El incremento en el número de replicaciones del experimento original está directamente relacionado con el incremento de las versiones del material experimental, que ocasiona comúnmente confusión y desorden en su organización. En este trabajo, realizamos un mapeo sistemático de la literatura (MSL para localizar trabajos sobre Gestión de Materiales Experimentales y su Uso en Replicaciones en Ingeniería de Software Experimental. Los resultados encontrados reflejan la escasa existencia de artículos sobre esta temática. Además, el análisis de los estudios encontrados ha descubierto que dichos artículos, en su mayoría, adolecen de problemas en la gestión de versiones de materiales experimentales para poder llevar a cabo un proceso de replicación. Estos datos proporcionan información de interés para iniciar la investigación de la adopción del paradigma de gestión de configuración de software en la gestión del material experimental en ISE.

  14. Patrones iniciales de sucesión en claros experimentales de plantaciones de Pinus patula en el Embalse de Chisacá, Usme, Cundinamarca (Colombia

    Directory of Open Access Journals (Sweden)

    Vargas Ríos Orlando

    2006-06-01

    Full Text Available Se presenta un estudio que determina el efecto de la creación de claros experimentales con diferentes densidades sobre los patrones iniciales de sucesión dentro de plantaciones de Pinus patula. Adicionalmente, se evaluó el efecto de la remoción de acículas del suelo. Antes del establecimiento de los claros ya se encontraban en las parcelas la mayoría de las especies (30, pero en muy baja proporción; luego del aclareo, se registraron
    25 especies determinadas entre plantas vasculares (20 y no vasculares (5; 13 de éstas resultaron de mayor relevancia debido a su mayor cobertura en las parcelas. Se pudo establecer que la apertura de claros, además de la mayor disponibilidad de luz solar, permite una mayor entrada de agua, con lo cual se estimula la germinación, crecimiento y establecimiento de individuos relativamente rápido. Se determinó que existe un banco de semillas dentro de las acículas del suelo. Es importante continuar con el monitoreo de las parcelas para un mejor entendimiento del fenómeno sucesional que ocurre.

  15. Nuevos datos experimentales sobre parámetros hidrogeológicos de la Cuenca de Madrid obtenidos a partir de muestras de sondeos

    Directory of Open Access Journals (Sweden)

    Villarroya Gil, F. I.

    1990-12-01

    Full Text Available A critical review of main hydrogeological parameters (porosity, permeability and specific storage coefficient of Madrid Basin Detrital Aquifer is done. For this study, data from the bibliography and new laboratory analysis of grain size distribution (26, dry density (26, specific weight (26, permeability (20 and consolidation test (6 samples from three boreholes are used. The results are quite similar to those than already exist in the literature, although the porosity obtained is higher.Se hace una revisión crítica de los principales parámetros hidrogeológicos (porosidad, permeabilidad y coeficiente de almacenamiento específico, del Terciario detrítico de la cuenca de Madrid. Para este estudio además de los datos existentes en la bibliografía, se han realizado una serie de análisis de laboratorio desarrollados en las instalaciones del SGOP obteniendo, de esta manera, nuevos valores experimentales de los citados parámetros, mediante ensayos granulométricos (26, de densidad seca (26, de peso específico (26, de permeabilidad (20 y ensayos edométricos (6. Las muestras proceden de tres sondeos realizados en el casco urbano de Madrid por el SGOP (MOPU. Los resultados obtenidos coinciden, en gran medida, con los existentes en la bibliografía, si bien, los valores de porosidad total son marcadamente más altos.

  16. Aplicación práctica de métodos estereológicos renales en modelos animales experimentales

    Directory of Open Access Journals (Sweden)

    María Teresa Fernández García

    2017-01-01

    Full Text Available Los riñones son órganos vitales que realizan funciones de excreción, equilibrio hidroelectrolítico y producción de hormonas. La nefrona es su unidad estructural y funcional. El número, tamaño y distribución de los componentes de la nefrona contienen información relevante sobre la función renal. La estereología es una rama de la morfometría que permite, aplicando reglas matemáticas, obtener información tridimensional de estructuras biológicas a partir de cortes microscópicos bidimensionales, seriados, paralelos y equidistantes. Ante la complejidad de los estudios estereológicos y la carencia de una bibliografía clara sobre el desarrollo de los mismos, el objetivo de este trabajo es explicar de forma sencilla y con ejemplos, utilizando un modelo animal, los conceptos básicos de estereología, así como el cálculo de los principales parámetros estereológicos renales y que estos puedan ser aplicados en futuros estudios experimentales.

  17. Análisis conductual aplicado en neuropsicología: fundamentos teóricos, experimentales y empíricos.

    Directory of Open Access Journals (Sweden)

    José Alonso Aguilar-Valera

    2016-01-01

    Full Text Available El presente artículo presenta una revisión teórica donde se expone la importancia que tienen los principios y técnicas conductuales dentro del ámbito de la rehabilitación neuropsicológica. En la intervención clínica con pacientes víctimas de disfunción, daño o deterioro neurológico, donde las consecuencias directas sobre el comportamiento son significativas, el uso de las estrategias provenientes de las técnicas de modificación de conducta (conductuales y/o conductual-cognitivas son importantes para el tratamiento de los diversos síndromes neuroconductuales, estando dentro de las competencias del especialista en esta área aplicada de las neurociencias. Además de describirse tanto aspectos teóricos como experimentales de principal relevancia para estos fines, también se mencionarán algunos estudios empíricos llevados a cabo, bajo una metodología de caso único, para una mejor comprensión sobre la utilidad aplicativa de los principios conductuales en el ámbito de la neuropsicología clínica.

  18. Contacto normal entre un medio elasto-plástico continuo y una esfera rígida : observaciones experimentales y computacionales

    Directory of Open Access Journals (Sweden)

    Ángela María Pedraza

    2005-01-01

    Full Text Available Se presenta en este trabajo una investigación experimental y numérica del contacto normal de una esfera rígida con una placa plana de material cuyo comportamiento mecánico se asume de tipo elasto-plástico. Los esfuerzos locales bajo el punto de contacto se han obtenido experimentalmente mediante visualización foto-elástica. Se ha evaluado numéricamente la evolución de los bulbos de esfuerzo bajo el punto contacto como función del tiempo y se ha efectuado la comparación con las observaciones experimentales. Los resultados indican que un modelo elasto-plástico tridimensional reproduce de manera apropiada las características principales observadas en los experimentos físicos. Este ejercicio puramente académico y de carácter didáctico enfatiza en el enorme potencial de los elementos finitos en la solución de problemas de deformación bajo diferentes tipos de modelos constitutivos y pone de manifiesto la enorme utilidad del modelamiento matemático y computacional basado en aproximaciones continuas de la materia

  19. Etude des propriétés magnéto-optiques des couches minces à base ...

    African Journals Online (AJOL)

    Etude des propriétés magnéto-optiques des couches minces à base de ferrite de cobalt obtenues par voie sol-gel. ... This requires only the use of magnetic fluids or ferro fluids, silica precursors (cheap) and a glass substrate. The goal is to obtain thin layers and study their magneto-optical properties. The curves obtained for ...

  20. Etude des profils cognitifs chez les apparentes de personnes avec autisme : Hypothese d?un manque de flexibilite cognitive ?

    OpenAIRE

    2009-01-01

    Resume Cette recherche porte sur l?etude des profils cognitifs d?apparentes (parents/fratrie) de personnes avec autisme, comparativement a une population de temoins. Methodologie Sept tests cognitifs appartenant aux trois domaines explores dans l?autisme ? fonctions executives, coherence centrale et theorie de l?esprit ? ont ete proposes a 58 apparentes (39 parents; 19 freres et s?urs) de personnes avec autisme, comparativement a 34 temoins apparies sur l?age,...

  1. 85 La Préposition Française: Etude des Contraintes d'emploi Chez l ...

    African Journals Online (AJOL)

    Ike Odimegwu

    La Préposition Française: Etude des Contraintes d'emploi. Chez l'apprenant Igbophone. Scholastica U. Ezeodili et Emmanuel O. Ezeani*. Résumé. Plusieurs facteurs linguistiques nuisent à la compétence de l'apprenant igbophone du français langue étrangère. Il faut en particulier souligner le manque de connaissance.

  2. Study of the tributyl phosphate - 30% dodecane solvent; Etude du solvant phosphate tributylique - 30 % dodecane

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, P. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses. Centre d' Etudes Nucleaires, 92 (France)

    1967-07-01

    This study, originating mainly from a literature survey, gives the principal chemical and physical features of the tributyl-phosphate (TBP) agent diluted at 30 volumes per cent in dodecane. The mixture is a very commonly used extractant in nuclear fuel processing. In this paper, the main following points are reported: -) the components (TBP and diluents) -) the TBP-diluents systems (non-loaded), -) the TBP-diluents-water systems, -) TBP-diluents-water-nitric acid systems, and -) industrial solvents. (author) [French] Cette etude, d'origine bibliographique, regroupe les caracteristiques physico-chimiques essentielles du phosphate tributylique (TBP) dilue a 30% en volume dans du dodecane. Ce melange constitue un agent d'extraction tres utilise dans le traitement des combustibles nucleaires. Les principaux points traites sont les suivants: -) les constituants (TBP et diluants), -) les systemes TBP-diluants non charges, -) les systemes TBP-diluants-eau, -) les systemes TBP-diluants-eau-acide nitrique, et -) les solvants industriels. (auteur)

  3. Spectroscopic study of near closed-shell nuclei Z = 50, by means of the ({sup 3}He,d) and (d, {sup 3}He) reactions on all even tin isotopes, and the ({sup 3}He, d) reaction on the A = 113 and A = 115 indium isotopes; Etude spectroscopique des noyaux au voisinage de la couche fermee Z = 50, au moyen des reactions ({sup 3}He, d) et (d, {sup 3}He) sur tous les isotopes pairs de l'etain, et de la reaction ({sup 3}He, d) sur les isotopes 113, 115 de l'indium

    Energy Technology Data Exchange (ETDEWEB)

    Harar, S. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-06-01

    A systematic study of ({sup 3}He, d) reactions at 18 MeV incident energy and (d, {sup 3}He) reactions at 22 MeV incident energy on {sup 112,114,116,118,120,122,124}Sn is presented. The distorted wave Born approximation (DWBA) is used to extract informations on (a) the transferred angular momentum l{sub p}, (b) the change of parity and (c) the spectroscopic factor. We have investigated the influence of the proton-neutron residual interaction on the spread of the pure proton configuration (particle or hole), and on the observed level sequence. Experimental results and predictions of the Kisslinger and Sorensen model are in reasonable agreement. A study of {sup 113,115}In ({sup 3}He, d) {sup 114,116}Sn reactions shows strong experimental evidence that the proton particle hole components are weak in the first excited states of tin nuclei. Furthermore, highly excited states ({approx} 4 to 6 MeV) having a simple structure with one predominant particle-hole configuration have been located. (authors) [French] Nous presentons une etude systematique des reactions ({sup 3}He, d) a 18 MeV et (d, {sup 3}He) a 22 MeV sur {sup 112,114,116,118,120,122,124}Sn. L'approximation des ondes deformees (DWBA) est utilisee pour obtenir des informations sur le moment angulaire transfere l{sub p}, sur le changement de parite et le facteur spectroscopique. Nous avons etudie l'influence de l'interaction residuelle proton-neutron sur la repartition de l'intensite a une seule particule ou trou de proton, et sur les sequences des niveaux observes. Les resultats experimentaux et les previsions theoriques du modele de Kisslinger et Sorensen sont en assez bon accord. L'etude des reactions {sup 113,115}In ({sup 3}He, d) {sup 114,116}Sn apporte la preuve experimentale que les composantes particule - trou de protons des premiers etats excites des noyaux residuels sont faibles. Elle permet aussi de localiser des niveaux a une energie d'excitation elevee ({approx} 4 a 6 Me

  4. Loxoscelismo en Chile: estudios epidemiológicos, clínicos y experimentales Loxoscelism in Chile: epidemiological, clinical and experimental studies

    Directory of Open Access Journals (Sweden)

    Hugo Schenone

    1989-12-01

    Full Text Available Se presenta un enfoque panorámico de estudios epidemiológicos, clínicos y experimentales referentes a Loxosceles laeta y loxoscelismo efectuados en 1955-1988 en Santiago, Chile. Se estudiaron 216 casos de loxoscelismo. Los hechos más relevantes fueron: 52,8% correspondió a mujeres; edad entre 7 meses y 78 años; 84,3% fué loxoscelismo cutáneo (LO y 15,7% loxoscelismo cutáneo-visceral (LCV; 73,6% sucedió en época calurosa; en 86,6% el accidente ocurrió en la vivienda, especialmente en dormitorios, mientras la persona dormía o se vestía. La araña fué vista en 60,2% de los casos e identificada en laboratorio como L. laeta en 17,7% (10,6% de los 216 casos. Los sitios más frecuen temente afectados fueron las extremidades con 67,6%, lancetazo urente fué el síntoma inicial más frecuente. Dolor, edema y placa livedoide, la cual posteriormente se transformaría en escara necrótica, fueron las manifestaciones locales predominantes. En LCV hematuria y hemoglobinuria fueron constantes, ictericia, fiebre y compromiso de conciencia se presentaron en la mayoría de los casos. Tratamiento: LC con antihistamínicos o corticoides inyectables, LCV con corti-coides inyectables. La condición de los pacientes en el último control fué: curación completa en 75,5%, curación con secuela cicatrizal en 8,3%, muerte en 3,7% (todos con LCV y abandono en 12,5%. Adicionalmente, se ha efectuado una serie de estudios experimentales, tanto in vivo como in vitro para esclarecer aspectos básicos sobre el veneno de L. laeta y el tratamiento del loxoscelismo.A panoramic sight of epidemiological, clinical and experimental studies, referring to Loxosceles laeta and loxoscelism, carried out in 1955-1988, in Santiago, Chile is presented. Two-hundred and sixteen cases of loxosce lism were studied. The most relevant features were: 84.3% corresponded to cutaneous loxosce lism (CD and 15.7% to viscerocutaneous loxos celism (VCD; 73.6% ocurred in hot season; in 86

  5. INCLUSIÓN DE HIBISCUS SABDARIFFA EN ALIMENTOS EXPERIMENTALES PARA MACROBRACHIUM TENELLUM: EFECTOS EN LA PIGMENTACIÓN, CRECIMIENTO Y SUPERVIVENCIA.

    Directory of Open Access Journals (Sweden)

    Martín A. Aréchiga P.

    2015-01-01

    Full Text Available En la naturaleza, los pigmentos tienen la principal función de colorear; sin embargo, también tienen efectos sobre el estado de salud y desarrollo de los organismos. Los compuestos sintéticos dirigidos a incrementar la coloración en organismos con importancia comercial, representan entre el 15 al 20% del costo de la dieta. Por lo anterior, la investigación sobre pigmentos de origen natural (más baratos y menos tóxicos se ha incrementado sustancialmente en los últimos años. Las antocianinas pueden ser utilizadas como una alternativa para la pigmentación de organismos. En este estudio se utilizaron los cálices de Hibiscus sabdariffa, planta popular que acumula antocianinas que proporciona su característico color rojo. Langostinos Macrobrachium tenellum fueron alimentados con dietas que incluían cálices de H. sabdariffa (jamaica bajo los siguientes tratamientos: i pigmento extraído con agua, ii pigmento extraído con etanol acidificado [0.1 M HCl (v/v], y iii harina de cálices. El efecto pigmentante de las dietas experimentales se comparó con langostinos sometidos a una dieta control sin pigmentos añadidos y con langostinos extraídos del medio silvestre. Los langostinos alimentados con la dieta de inclusión de polvo de jamaica mostraron la mayor expresión de eritróforos (color rojo en el exoesqueleto del pleon (abdomen y ganancia en longitud y peso, después de 60 días. Estos resultados sugieren que H. sabdariffa puede ser utilizado como complemento alimenticio natural, puesto que tiene un efecto positivo en los parámetros de crecimiento y pigmentación.

  6. (gahan) (hymenoptera : eulophidae)

    African Journals Online (AJOL)

    Etude experimentale de quelques parametres biologiques de ceranisus femoratus (gahan) (hymenoptera : eulophidae) un nouvel ennemi naturel Pour le controle de megalurothrips sjostedti (trybom) (thysanoptera : thripidae) ravageur du niebe au benin.

  7. Validez Estructurada para una investigación cuasi-experimental de calidad: se cumplen 50 años de la presentación en sociedad de los diseños cuasi-experimentales

    Directory of Open Access Journals (Sweden)

    Paula Fernández-García

    2014-05-01

    Full Text Available Investigación cuasi-experimental es aquella que tiene como objetivo poner a prueba una hipótesis causal manipulando (al menos una variable independiente donde por razones logísticas o éticas no se puede asignar las unidades de investigación aleatoriamente a los grupos. Debido a que muchas decisiones a nivel social se toman en base al resultado de investigaciones con estas características, es imperativo que tengan una planificación exquisita de la aplicación del tratamiento, del control en el proceso de la investigación y del análisis de los datos. El pasado año 2013 los diseños cuasi-experimentales cumplieron 50 años, y este trabajo es un homenaje a Campbell y a todos los investigadores que día a día aportan ideas para mejorar el método cuasi-experimental en alguno de sus aspectos. De la mano de una revisión de las investigaciones cuasi-experimentales publicadas en un período de 11 años en tres revistas de Psicología destacamos algunos aspectos que se refieren al cuidado del método. Finalizamos el trabajo proponiendo el concepto de Validez Estructurada, que en resumen, es el hilo conductor que debe seguir la realización de toda investigación para poner a prueba con garantía las hipótesis que responden a los objetivos que en ella se plantean, concretamente, en las investigaciones cuasi-experimentales.

  8. Propuesta didáctica basada en la Metodología de Aprendizaje Activo, encaminada a construir el concepto de difracción partiendo de prácticas experimentales

    OpenAIRE

    Manrique Torres, Carolina

    2012-01-01

    Este trabajo presenta una propuesta didáctica para docentes de secundaria basada en la metodología de aprendizaje activo (MAA), encaminada a construir el concepto de difracción por medio de prácticas experimentales realizadas en el aula de clase, por los estudiantes de grado undécimo en la asignatura de física. La difracción es un fenómeno de la óptica ondulatoria que ha permitido importantes aportes en el estudio de la física y que además puede evidenciarse fácilmente en un laboratorio y en ...

  9. La conformación del cáncer como objeto científico y problema sanitario en la Argentina: discursos, prácticas experimentales e iniciativas institucionales, 1903-1922

    OpenAIRE

    Buschini, José D.

    2014-01-01

    El trabajo analiza la conformación del cáncer como problema sanitario y como objeto científico en la Argentina en las dos primeras décadas del siglo XX. Se consideran la adquisición y circulación de conocimientos foráneos sobre el tema, el contexto en el que surgieron los primeros desarrollos experimentales, las iniciativas institucionales promovidas desde la profesión médica y el modo en que se logró interesar a las autoridades estatales y a la sociedad civil para darles curso. Se estudia de...

  10. Coeficientes de digestibilidad total y de proteínas en alimentos experimentales para juveniles de Oplegnathus insignis (Kner, 1867 (Perciformes, Oplegnathidae

    Directory of Open Access Journals (Sweden)

    Avelino Muñoz

    2015-05-01

    Full Text Available Los alimentos para peces están formulados con diversos ingredientes, donde la harina de pescado es la principal fuente de proteína. Sin embargo, este insumo tiene un alto costo que lleva a la necesidad de evaluar nuevas fuentes de proteínas y probarlas en especies marinas. Oplegnathus insignis (San Pedro, Pacific beakfish es una especie omnívora en su etapa intermareal y carnívora en su etapa submareal, que ha sido cultivada de manera experimental, siendo necesario incorporar dietas formuladas. Este estudio reporta la experiencia en alimentación y nutrición, de juveniles de O. insignis alimentados con dietas formuladas con distintas fuentes de proteína. Se efectuó una experiencia con juveniles de O. insignis provenientes de un cultivo experimental. Se formularon cuatro alimentos, uno en base de harina de pescado (referencia y tres modificando la fuente de proteína del alimento de referencia, intercambiando un 30% de harina de pescado, por harina de soya, harina de moluscos y harina de quinoa. Se experimentó con 180 ind de 295,6 g y de 450 días post-eclosión, distribuidos en 12 estanques rectangulares de 1,6 m³. La alimentación fue a saciedad. Se efectuaron análisis próximales de los alimentos experimentales de las heces colectadas. Se determinó los coeficientes de digestibilidad total y proteína. El alimento con mayor contenido de proteína fue el que contenía harina de moluscos. El mayor coeficiente de digestibilidad total lo tienen los alimentos con harina de pescado (68,0% y harina de moluscos (67,1%, mientras que en los alimentos en base a harinas vegetales, la digestibilidad total para la harina de soya fue de 62,7% y para harina de quinoa de 64,1%. Estos resultados indican que es factible reemplazar un 30% de la harina de pescado por harinas de origen vegetal.

  11. Pharmacological study of radioactive-gold colloid transport by blood and by serous exudate; Contribution a l'etude pharmacologique du transport des colloides d'or radioactif par le sang et les exsudats sereux

    Energy Technology Data Exchange (ETDEWEB)

    Rousselet, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-06-01

    substances et particulierement dans le transport de l'or colloidal radioactif. Les fractions sanguines qui peuvent participer au transport de l'or colloidal sont les hematies, les leucocytes et elements histiocytaires, et le plasma. La repartition de la radioactivite dans ces elements est precisee en pratiquant des autoradiographies de coupes de culots de sang centrifuge et congele apres incubation avec de l'or colloidal. Cette etude montre l'importance du plasma dans le transport des particules radioactives. Nous avons alors recherche une fixation eventuelle de l'or colloidal 198 sur les diverses proteines seriques en appliquant certaines methodes de separation a savoir une filtration-exclusion sur colonne de gel de Sephadex G-200 et un fractionnement electrophoretique sur papier et sur acetate de cellulose gelatineux (cellogel). Nous avons etudie la liaison ''in vitro'' et ''in vivo'' des particules colloidales d'or 198 d'abord avec les proteines seriques de sujets sains puis avec les proteines des liquides d'epanchement d'origine pathologique, chez l'homme, ou du a une inflammation experimentale a la carragenine chez le rat. Les particules d'or colloidal 198 de 30 m{mu} (S-2) sont liees dans une certaine mesure aux {alpha}2 globulines sanguines ou ascitiques, celles de 5 m{mu} (S-6) sont liees aux {alpha}1 globulines de meme que les grains contenus dans l'or polydisperse. Cette liaison semble intervenir grace a la couche protectrice de macromolecules constituees par la gelatine. Seules les caracteristiques physicochimiques de grains colloidaux peuvent expliquer leur difference de localisation sur l'electrophoregramme. L'or sous forme ionique, par contre, est combine, aux seules albumines si la quantite de metal presente ne depasse pas une certaine limite. (auteur)

  12. Determination experimentale des principales caracteristiques ...

    African Journals Online (AJOL)

    Il s'agit de la masse volumique basale, des taux de retraits totaux linéaire et volumique, du module d'Young dans la direction du fil du bois en flexion quatre points ainsi que la contrainte de rupture en traction simple, en compression simple, au cisaillement simple et enflexion quatre points. Borassus aethiopum is a palm ...

  13. Insight et capacite a consentir au soin et a la recherche: etude exploratoire et points de vue ethiques

    OpenAIRE

    Capdevielle, D.; Raffard, S.; Bayard, S.; Boulenger, J.-P.

    2011-01-01

    Resume La question de la capacite a consentir a un traitement ou a la recherche se pose pour tous les patients, mais peut-etre de facon plus cruciale pour les patients souffrant de troubles mentaux. Afin de repondre a cette question, plusieurs auteurs se sont interesses aux liens entre les symptomes cliniques de la schizophrenie et la capacite a consentir. Le but de notre etude est d?evaluer les liens entre la capacite a consentir et un symptome d?un grand interet dans la schizophr...

  14. Etude de noyaux légers riches en neutrons à l'aide du multidétecteur TONNERRE

    OpenAIRE

    Piétri, S.

    2003-01-01

    This work concern the technical development made on the multidetector TONNERRE and the study of the 34Si nucleus by a complete beta-neutron-gamma spectroscopy. In the first part various tests performed on modules of the detector in the "Centre d'Etude de Bruyère le Châtel" are presented. A modification of the embassies of the photomultipliers tubes allows to gain more than 50% in the neutron efficiency and to obtain a threshold lower than 300 keV for the neutron energy. A complete C++ simula...

  15. Study of copper fluorination; Contribution a l'etude de la fluoruration du cuivre

    Energy Technology Data Exchange (ETDEWEB)

    Gillardeau, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-02-01

    This report deals with the action of fluorine on copper. Comprehensive descriptions are given of the particular technological methods and of the preparation of the reactants. This fluorination reaction has been studied at medium and low fluorine pressures. A nucleation and growth phenomenon is described. The influence of a pollution of the gas phase on the fluorination process is described. The solid-state reaction between cupric fluoride and cooper has also been studied. A special study has been made of the growth of copper deposits by thermal decomposition of gaseous fluorides. (author) [French] Ce rapport traite de la reaction du fluor sur le cuivre. Les methodes technologiques particulieres ainsi que les preparations des reactifs sont largement developpees. Cette reaction de fluoruration est etudiee sous pressions moyennes et sous basses pressions de fluor. Un phenomene de germination et croissance est decrit. L'influence de la pollution de la phase gazeuse sur le processus de fluoruration est rapportee. La reaction a l'etat solide du fluorure cuivrique sur le cuivre a egalement ete etudiee. La croissance de depots de cuivre par decomposition thermique des fluorures de cuivre gazeux fait l'objet d'une etude speciale. (auteur)

  16. Preparation and study of dialkyl nitroxide radicals; Preparation et etude de radicaux nitroxydes diacyles

    Energy Technology Data Exchange (ETDEWEB)

    Chenavas, P. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    These radicals are obtained by oxidation of N-hydroxy-imides with lead tetracetate or p-nitro-perbenzoic acid. These imides are prepared by heating dicarboxylic acids anhydrides with benzyloxy-amine followed by catalytic hydrogenation of N-benzyloxy-imides so obtained. Two series of radicals have mainly been studied, the first concerning five-membered cyclic imides, the second six-membered cyclic imides, these molecules having methyls substituents or no on the carbon ring. N. M. R. spectra of some O-benzyl-imides have been analysed. These different results have made it possible to study the conformation and stereochemistry of these imides. (author) [French] Ces radicaux sont obtenus par oxydation d'imides N-hydroxyles par le tetracetate de plomb ou l'acide p-nitroperbenzoique; ces imides sont prepares par chauffage d'anhydrides de diacides en presence de benzyloxyamine suivie d'une hydrogenation catalytique des N-benzyloxyimides ainsi obtenus. Deux series de radicaux ont principalement ete etudies: la premiere relative a des imides cycliques a cinq chainons, la seconde a des imides cycliques a six chainons, ces molecules ayant des substituants methyles ou non sur la chaine carbonee. Les derives O-benzyles de quelques-uns de ces imides ont ete analyses en R. M. N. Ces differents resultats ont permis une etude de la conformation et de la stereochimie de ces imides. (auteur)

  17. Etude de l'affaiblissement du comportement mecanique du pergelisol du au rechauffement climatique

    Science.gov (United States)

    Buteau, Sylvie

    Le rechauffement climatique predit pour les prochaines decennies, aura des impacts majeurs sur le pergelisol qui sont tres peu documentes pour l'instant. La presente etude a pour but d'evaluer ces impacts sur les proprietes mecaniques du pergelisol et sa stabilite a long terme. Une nouvelle technique d'essai de penetration au cone a taux de deformation controle, a ete developpee pour caracteriser en place le pergelisol. Ces essais geotechniques et la mesure de differentes proprietes physiques ont ete effectues sur une butte de pergelisol au cours du printemps 2000. Le developpement et l'utilisation d'un modele geothermique 1D tenant compte de la thermodependance du comportement mecanique ont permis d'evaluer que les etendues de pergelisol chaud deviendraient instables a la suite d'un rechauffement de l'ordre de 5°C sur cent ans. En effet, la resistance mecanique du pergelisol diminuera alors rapidement jusqu'a 11,6 MPa, ce qui correspond a une perte relative de 98% de la resistance par rapport a un scenario sans rechauffement.

  18. Estrategias experimentales para el estudio de las propiedades de la proteína Core del virus de la hepatitis C

    Directory of Open Access Journals (Sweden)

    Gonzálo Correa Arango

    2004-03-01

    Full Text Available

    El modelo de infección por el Virus de la Hepatitis C (VHC se ha convertido en el tópico de interés de numerosos equipos de investigación, considerando el alto porcentaje de infección persistente asociada al VHC. En efecto, del 50 al 80% de los pacientes con infección por el VHC, desarrollan infección persistente, que puede evolucionar a cirrosis y carcinoma hepatocelular (HCC. Este modelo presenta dos obstáculos mayores para su estudio: la ausencia de un sistema eficiente de replicación viral in vitro y el limitado número de modelos animales.

    La proteína Core del VHC, además de ser la unidad estructural de la cápside viral, parece estar implicada en las estrategias virales de persistencia y oncogénesis; nuestro grupo ha planteado estrategias experimentales para estudiar algunas de sus propiedades, tales como su capacidad inmunonoduladora en cultivos de cálulas dendríticas humanas, su capacidad de modificar la expresión del ARNm en células HepG2 con expresión transitoria de Core y la presencia de esta proteína en tejido hepático proveniente de pacientes con diagnóstico de HCC; dichas estrategias experimentales han sido:

    Producción de la proteína Core del VHC en el sistema baculovirus y purificación en condiciones nativas para su evaluación en ensayos biológicos.

    Expresión transitoria de la proteína Core del VHC en la línea celular HepG2, mediante transducción con partículas recombinantes del Virus Semliki Forest (SFV.

    Estudio de la expresión de p53

  19. Etude comparative

    African Journals Online (AJOL)

    dosage of Portulaca Oleracea and Extra-Egg®. The dosage of the luteinic hormone (LH) and the prolactine (PRL) has given a plasmatic level of 3703.39 ± 30.34 mUI/L for the LH and 63.18 ± 0.25 ng/L for the PRL about the treatment C during three months and half. Regarding the treatment G with 2 g/L of water of Portulaca ...

  20. Contribution to the study of french pitchblendes; Contribution a l'etude des pechblendes francaises

    Energy Technology Data Exchange (ETDEWEB)

    Geffroy, J. [Commissariat a l' Energie Atomique, Lab. de Mineralogie, Centre de Chatillon (France). Centre d' Etudes Nucleaires; Sarcia, J.A. [Commissariat a l' Energie Atomique, Div. de la Crouzille, Haute Vienne (France). Centre d' Etudes Nucleaires

    1955-07-01

    The authors first review the characteristics of uraninite-pitchblende, as deduced of present literature. They set apart from typical pitchblende a black oxide aspect, which probably corresponds to neo-formations, and a 'para-pitchblende' aspect, which they relate to deep sur-oxidation of normal pitchblende. They insist on the easy replacement of pitchblende by silica. and give indications as to changes in vein stones (fluorite, quartz, etc...). A detailed study of paragenesis and successions in french uranium districts follows (including discussion of uranium of uranium-bearing coals). The authors attempt to classify french pitchblende veins. They are chiefly epithermal and poor in satellite ores. Three types of deposits are identified: massive - pitchblende type, silica type, fluorite type. These deposits, as those of Portugal, are included in granite, Central-European peri-batholitic types where uranium associates which Ni, Co, Bi and Ag, are in France both rare and poor. Finally, the authors attempt to bring out in the european Hercynian area a particular distribution of paragenetic types. (authors) [French] Les auteurs recapitulent d'abord les caracteres et les occurences de l'uraninite - pechblende, tels qu'ils peuvent etre degages de l'actuelle bibliographie. Ils exposent ensuite les faits qui du point de vue mineralogique seulement ressortent de l'etude mineralogique et chalcographique des pechblendes francaises et de leurs satellites. Ils distinguent de la pechblende-type un facies oxyde noir; correspondant probablement a une neoformation, et un facies parapechblende, qui est rapporte a une sur oxydation hypogene de la pechblende proprement dite. Ils insistent sur le facile remaniement de la pechblende par la slice; et donnent quelques precisions sur les modifications des gangues (fluorine, quartz, etc...). Suit l'etude detaillee des parageneses et des successions dans les districts uraniferes francais: Divisions du

  1. Etude de la dynamique des porteurs dans des nanofils de silicium par spectroscopie terahertz

    Science.gov (United States)

    Beaudoin, Alexandre

    Ce memoire presente une etude des proprietes de conduction electrique et de la dynamique temporelle des porteurs de charges dans des nanofils de silicium sondes par rayonnement terahertz. Les cas de nanofils de silicium non intentionnellement dopes et dopes type n sont compares pour differentes configurations du montage experimental. Les mesures de spectroscopie terahertz en transmission montre qu'il est possible de detecter la presence de dopants dans les nanofils via leur absorption du rayonnement terahertz (˜ 1--12 meV). Les difficultes de modelisation de la transmission d'une impulsion electromagnetique dans un systeme de nanofils sont egalement discutees. La detection differentielle, une modification au systeme de spectroscopie terahertz, est testee et ses performances sont comparees au montage de caracterisation standard. Les instructions et des recommendations pour la mise en place de ce type de mesure sont incluses. Les resultats d'une experience de pompe optique-sonde terahertz sont egalement presentes. Dans cette experience, les porteurs de charge temporairement crees suite a l'absorption de la pompe optique (lambda ˜ 800 nm) dans les nanofils (les photoporteurs) s'ajoutent aux porteurs initialement presents et augmentent done l'absorption du rayonnement terahertz. Premierement, l'anisotropie de l'absorption terahertz et de la pompe optique par les nanofils est demontree. Deuxiemement, le temps de recombinaison des photoporteurs est etudie en fonction du nombre de photoporteurs injectes. Une hypothese expliquant les comportements observes pour les nanofils non-dopes et dopes-n est presentee. Troisiemement, la photoconductivite est extraite pour les nanofils non-dopes et dopes-n sur une plage de 0.5 a 2 THz. Un lissage sur la photoconductivite permet d'estimer le nombre de dopants dans les nanofils dopes-n. Mots-cles: nanofil, silicium, terahertz, conductivite, spectroscopie, photoconductivite.

  2. Experimental study of chemical-mechanical coupling during percolation of reactive fluid through rocks under stress, in the context of the CO{sub 2} geological sequestration; Etude experimentale du couplage chimie-mecanique lors de la percolation d'un fluide reactif dans des roches sous contrainte, dans le contexte de la sequestration geologique du CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Le Guen, Y

    2006-10-15

    CO{sub 2} injection into geological repositories will induce chemical and mechanical instabilities. The study of these instabilities is based on experimental deformation of natural rock samples under stress, in the presence of fluids containing, or not, dissolved CO{sub 2}. Triaxial cells used for the experiments permitted an independent control and measurement of stress, temperature, fluid pressure and composition. Vertical strains were measured during several months, with a resolution of 1.10{sup -12} s{sup -1} on the strain rate. Simultaneously, fluids were analysed in order to quantify fluid-rock interactions. For limestone samples, percolation of CO{sub 2}-rich fluids increases strain rate by a factor 1.7 up to 5; on the other hand, sandstone deformation remained almost the same. Increase in strain rate with limestone samples was explained by injected water acidification by the CO{sub 2} which increases rock solubility and reaction kinetics. On the opposite, small effect of CO{sub 2} on quartz explains the absence of deformation. X-ray observations confirmed the importance of rock composition and structure on the porosity evolution. Numerical simulations of rock elastic properties showed increasing shear stress into the sample. Measured deformation showed an evolution of reservoir rocks mechanical properties. It was interpreted as the consequence of pressure solution mechanisms both at grains contacts and on grain free surfaces. (author)

  3. Experimental and theoretical study of Bragg-Fresnel focalizing optical systems engraved on multi layers interferential mirrors adapted to X and X-UV fields; Etude experimentale et theorique d`optiques focalisantes de type Bragg-Fresnel gravees sur des miroirs interferentiels multicouches adaptes aux domaines X et X-UV

    Energy Technology Data Exchange (ETDEWEB)

    Idir, M.

    1995-02-01

    This work concerns the study of a particular type of X-ray focusing optics known as Bragg-Fresnel lenses, formed through ion-etching of multilayered structures. Using the Super-ACO (LURE/Orsay) synchrotron storage ring, we tested several Bragg-Fresnel lenses having either linear or elliptical geometries (producing a line or a point focus, respectively). Diffraction profiles were first obtained for the linear lenses ion-etched on W/Si multilayers of nano-metric period. The experimental results were compared with our theoretical predictions. We next proposed and tested a solution to the problem superposing the different diffraction orders in the focal plane, that of fabricating Bragg-Fresnel lenses with an off-axis configuration, first for the linear and then the elliptical geometry. An experimental application, for an off-axis elliptical lens produced a focused X-ray spot of 5 x 10 microns{sup 2} for the Super-ACO synchrotron source. The same lens also produced a 1/3-size X-ray image of a grid-like object at 1750 eV using the first and third diffraction orders. (author).

  4. Theoretical and experimental study of the bio-geochemical behaviour of americium 241 in simplified rhizosphere conditions. Application to a calcareous agricultural soil; Etude theorique et experimentale du comportement biogeochimique de l'americium-241 en conditions rhizospheriques simplifiees. Application dans un sol agricole calcaire

    Energy Technology Data Exchange (ETDEWEB)

    Perrier, T

    2004-06-01

    Americium 241, is one of the most radio-toxic contaminant produced during the nuclear fuel cycle. It can be found in all environmental compartments, in particular the soils. The main goals of this study are to identify, quantify and model the effect of the main factors controlling the mobility of {sup 241}Am in the rhizosphere and the agricultural soils. The physico-chemical parameters of the soil and of the soil solution, the potential role of microorganisms on the sorption-desorption processes, and the speciation of americium in solution have been more particularly studied. {sup 241}Am remobilization has been studied at the laboratory using leaching experiments performed in controlled conditions on reworked calcareous soils artificially contaminated with {sup 241}Am. The soil samples have been washed out in different hydrodynamic conditions by solutions with various compositions. The eluted solution has been analyzed (pH, conductivity, ionic composition, Fe{sub tot}, organic acids, {sup 241}Am) and its bacterial biomass content too. The overall results indicate that {sup 241}Am remobilization is contrasted and strongly linked with the condition under study (pH, ionic strength, glucose and/or citrate concentration). Therefore, a solution in equilibrium with the soil or containing small exudate concentrations (10{sup -4} M) re-mobilizes only a very small part of the americium fixed on the solid phase. The desorption of {sup 241}Am corresponds to a solid/liquid coefficient of partition (K{sub d}) of about 10{sup 5} L.kg{sup -1}. A significant addition of glucose induces an important dissolution of soil carbonates by the indirect action of microorganisms, but does not significantly favor the {sup 241}Am remobilization. On the other hand, the presence of strong citrate concentrations ({>=} 10{sup -2} M) allows 300 to 10000 time greater re-mobilizations by the complexing of {sup 241}Am released after the dissolution of the carrying phases. Finally, the colloidal transport of {sup 241}Am has been systematically observed in a limited but significant extend and can represent up to 90% of the transported contamination. Therefore, it is impossible to estimate the mobility of americium in this part of the soil without taking into consideration the complexity and interconnection of the different processes involved: solid speciation of the element (mainly combined with carbonates and iron oxides), speciation in solution dependent of the microorganisms activity (complexing with citrate ions, pH etc.), and dynamics of the solutes transfer. The relative contribution of these inter-dependent processes remains difficult to evaluate with the macroscopic tools implemented. The modeling possibilities for this system are discussed on the basis of the different experimental data obtained (retention profiles, physico-chemical variations, K{sub d}) and using a consistent thermodynamical database completed for the needs of this study. (J.S.)

  5. New experimental method to study the collective modes in exotic nuclei; influence of the superfluidity on the cooling time of a neutron star; Nouvelle methode experimentale dediee a l'etude des modes collectifs dans les noyaux exotiques; influence de la superfluidite sur le temps de refroidissement d'une etoile a neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Monrozeau, Ch

    2007-07-15

    Giant monopole (GMR) and quadrupole (GQR) resonances have been measured in the {sup 56}Ni using inelastic scattering of 50 A.MeV deuteron at the Grand Accelerateur National d'Ions Lourds facility. This is the first experimental observation of isoscalar collective modes in a short-lived nucleus. The secondary beam was impinged on the active target Maya filled with a pure deuterium gas. Recoiling deuterons were detected in Maya and in a wall of nine silicon detectors. The GMR and GQR are centered at 19.3(0.5) and 16.2(0.5) MeV, respectively. Corresponding angular distributions were extracted from 3 to 7 degrees in the centre of mass frame. DWBA analysis based on RPA transition densities yields the percentage of the energy weighted sum rule exhausted: 136(27) % for the GMR et 76(13) % for the GQR. A finite temperature Hartree-Fock-Bogoliubov model was implemented to describe the 10 Wigner-Seitz cells which compose the inner crust of neutron stars and to microscopically calculate their specific heat. Calculations are performed with two contact pairing forces chosen to simulate the pairing properties of uniform neutron matter corresponding to the BCS approximation and to polarisation effects. Under the assumption of a rapid cooling of the core and an initial temperature of 100 keV in the inner crust, the cooling time of the star was estimated at 9 and 34 years, respectively. (author)

  6. Methodological study of the diffusion of interacting cations through clays. Application: experimental tests and simulation of coupled chemistry-diffusion transport of alkaline ions through a synthetical bentonite; Etude methodologique de la diffusion de cations interagissants dans les argiles. Application: mise en oeuvre experimentale et modelisation du couplage chimie-diffusion d'alcalins dans une bentonite synthetique

    Energy Technology Data Exchange (ETDEWEB)

    Melkior, Th

    2000-07-01

    The subject of this work deals with the project of underground disposal of radioactive wastes in deep geological formations. It concerns the study of the migration of radionuclides through clays. In these materials, the main transport mechanism is assumed to be diffusion under natural conditions. Therefore, some diffusion experiments are conducted. With interacting solutes which present a strong affinity for the material, the duration of these tests will be too long, for the range of concentrations of interest. An alternative is to determine on one hand the geochemical retention properties using batch tests and crushed rock samples and, on the other hand, to deduce the transport parameters from diffusion tests realised with a non-interacting tracer, tritiated water. These data are then used to simulate the migration of the reactive elements with a numerical code which can deal with coupled chemistry-diffusion equations. The validity of this approach is tested by comparing the numerical simulations with the results of diffusion experiments of cations through a clay. The subject is investigated in the case of the diffusion of cesium, lithium and sodium through a compacted sodium bentonite. The diffusion tests are realised with the through-diffusion method. The comparison between the experimental results and the simulations shows that the latter tends to under estimate the propagation of the considered species. The differences could be attributed to surface diffusion and to a decrease of the accessibility to the sites of fixation of the bentonite, from the conditions of clay suspensions in batch tests to the situation of compacted samples. The influence of the experimental apparatus used during the diffusion tests on the results of the measurement has also been tested. It showed that these apparatus have to be taken into consideration when the experimental data are interpreted. A specific model has been therefore developed with the numerical code CASTEM 2000. (author)

  7. Laser shocks on helium, hydrogen and diamond: an experimental study of the warm dense matter zone; Chocs laser sur l'helium, l'hydrogene et le diamant: une etude experimentale de la 'Warm Dense Matter'

    Energy Technology Data Exchange (ETDEWEB)

    Brygoo, St

    2006-11-15

    The purpose of this work was to develop a new approach of laser shocks on pre-compressed targets in order to collect data concerning the equation of state in the warm dense matter zone of the phase diagram. The accuracy of the measurement has been increased by the use of a new metrology based on quartz. Quartz is considered as a standard for the measurement of both the pressure and the density, a model of an isentropic relaxation based on a Grueneisen type approximation has been developed. By combining laser shocks with diamond anvil cells and by using this new metrology, we have investigated the following systems: diamond, helium, hydrogen, deuterium and hydrogen-helium mixtures. The results for helium agree very well with the predictions of the Saumon-Chabrier model. The results for deuterium are consistent with the latest results found in literature. As for the results concerning hydrogen, they have showed the limits of the quartz-based metrology. In fact, by being so little dense we are at the limit of the application range of the quartz relaxation. A mixture of helium-hydrogen (50 %) has been investigated, no sign of phase separation has been found.

  8. Self-ignition and oxidation of various hydrocarbons between 600 and 1000 K at high pressure: experimental study with fast compression machine and modeling; Autoinflammation et oxydation de divers hydrocarbures entre 600 et 1000 K a haute pression: etude experimentale en machine a compression rapide et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Ribaucour, M.

    2002-12-01

    Low- and intermediate-temperature oxidation and self-ignition of hydrocarbons play a major role in spark ignition, diesel and HCCI (homogenous charge compression ignition) engines. A deep understanding of the chemistry linked with both phenomena is necessary to improve the engines efficiency and to reduce the formation of pollutants. This document treats of works about the self-ignition and oxidation at high pressure of various hydrocarbons between 600 and 1000 deg. K. The experimental tool used is a fast compression machine fitted with a fast sampling system for the measurement of self-ignition delays and of the concentrations of intermediate oxidation products. The advantages and limitations of this tool are discussed. The self-ignition of various hydrocarbons is compared using pre-defined data which characterize the phenomenologies like cold flames, negative temperature coefficients and self-ignition limits. The hydrocarbons considered are pure or binary mixtures of alkanes, pent-1-ene and n-butyl-benzene. The development of high pressure oxidation reaction schemes of alkanes between 600 and 1000 deg. K is described. It is directly based on the analysis of intermediate oxidation products. This methodology is also applied to pent-1-ene and n-butyl-benzene. The construction of detailed thermo-kinetic models of oxidation and the modeling of phenomena are made for n-butane, n-heptane, for the 3 pentane isomers, for pent-1-ene and n-butyl-benzene. Finally, the perspectives of future works are evoked. They concern new modeling and new methodologies to be applied in more predictive thermo-kinetic models and the reduction of detailed models in order to include them inside fluid dynamics codes. (J.S.)

  9. Low temperature oxidation, co-oxidation and auto-ignition of olefinic and aromatic blending compounds: Experimental study of interactions during the oxidation of a surrogate fuel; Oxydation, co-oxydation et auto-inflammation a basses temperatures d'alcenes et aromatiques types: etude experimentale des interactions au sein d'un carburant-modele

    Energy Technology Data Exchange (ETDEWEB)

    Vanhove, G.

    2004-12-15

    The low-temperature (600-900 K) and high-pressure (5-25 bar) oxidation and auto-ignition of the three position isomers of hexene, of binary mixtures of 1-hexene, toluene and iso-octane, and of a surrogate fuel composed of these three compounds were studied in motor conditions using a rapid compression machine. Auto-ignition delay times were measured as long as intermediate products concentrations during the delay. The results show that the oxidation chemistry of the hexenes is very dependent on the position of the double bond inside the molecule, and that strong interactions between the oxidation mechanisms of hydrocarbons in mixtures can occur. The data obtained concerning the surrogate fuel give a good insight into the behaviour of a practical gasoline after an homogeneous charge compression. (author)

  10. Experimental study of the spin structure of the neutron ({sup 3}He) with low Q{sup 2}: a relationship between the Bjorken and Gerasimov-Drell-Hearn sum rules; Etude experimentale de la structure en spin du neutron ({sup 3}He) a bas Q{sup 2}: une connexion entre les regles de somme de Bjorken et Gerasimov-Drell-Hearn

    Energy Technology Data Exchange (ETDEWEB)

    Deur, A

    2000-10-01

    This thesis presents an experimental study of the neutron (and {sup 3}He) spin structure with a particular emphasis in the resonance domain (experiment E94010 that took place in 1997 at Jefferson Lab (TJNAF or formerly CEBAF) in Virginia). A polarized {sup 3}He target was built in order to achieve this study since polarized {sup 3}He nuclei can be seen as polarized neutrons. This target allowed the measurement of the polarized absolute cross sections {sigma}{sub 1/2}(Q{sup 2}, {nu}) and {sigma}{sub 3/2}(Q{sup 2}, {nu}) from the inclusive reaction {sup {sup {yields}}{sup 3}He}({sup {yields}}e, e')X for incident beam energies ranging from 0.86 GeV to 5.07 GeV at a scattering angle of 15.5 deg. The Q{sup 2} evolution of the generalized Gerasimov-Drell-Hearn (GDH) integral on {sup 3}He and on neutron was measured from 0.1 GeV{sup 2} to 1.0 GeV{sup 2} in order to understand the transition between perturbative QCD and non-perturbative QCD. The integration domain in {nu} (the energy loss of the scattered electron) is from the pion threshold to about 2.5 GeV which covers both the resonance region and the Deep Inelastic Scattering. The high precision of our data constrains the models giving the Q{sup 2} evolution of the generalized GDH integral. The polarized quasi-elastic scattering was also measured. The cross section {sigma}{sup TT}(Q{sup 2}, {nu}) on {sup 3}He and the spin structure functions g{sub 1}{sup {sup 3}He}(Q{sup 2}, {nu}) and g{sub 2}{sup {sup 3}He}(Q{sup 2}, {nu}) are presented. These data are an indication that the higher-twists are small in our kinematics domain and that the Bloom-Gilman duality seems to hold for the polarized spin structure functions. (author)

  11. Study of secondary electron emission from thin carbon targets with swift charged particles: heavy ions, hydrogen ions; Etude experimentale de l`emission electronique secondaire de cibles minces de carbone sous l`impact de projectiles rapides: ions lourds, ions hydrogene (atomiques, moleculaires ou sous forme d`agregats)

    Energy Technology Data Exchange (ETDEWEB)

    Billebaud, A.

    1995-07-12

    The main subject of this work is the study of electron emission from the two surfaces of thin solid targets bombarded with swift charged particles. The slowing down of swift ions in matter is mainly due to inelastic interaction with target electrons (ionization, excitation): the energy transfer to target electrons is responsible for the secondary electron emission process. The phenomenological and theoretical descriptions of this phenomena are the subject of the first chapter. We focused on secondary electron emission induced by different kind of projectiles on thin carbon foils. In chapter two we describe hydrogen cluster induced electron emission measurement between 40 and 120 keV/proton. These projectiles, composed of several atoms, allowed us to study and highlight collective effects of the electron emission process. We extended our study of electron emission to molecular (H{sub 2}{sup +}, H{sub 3}{sup +}) and composite (H{sup -}, H{sup 0}) projectiles at higher energies (<= 2 MeV): we have designed an experimental set-up devoted to electron emission statistics measurements which allowed us to study, among others things, the role of projectile electrons in secondary electron emission. This experiment is described in the third chapter. Finally, the fourth chapter describes new measurements of electron emission induced by energetic (13 MeV/u) and highly charged argon ion provided by the medium energy beam line (SME) of GANIL (Caen), which have been analyzed in the framework of a semi-empirical model of secondary electron emission. This set of experiments brings new results on composite projectile interaction with matter, and on the consequences of high energy deposition in solids. (author).

  12. Theoretical and experimental study of two-frequency solid-state lasers in the GHz to THz ranges. Opto-microwave applications waves; Etude theorique et experimentale des lasers solides bi-frequences dans les domaines GHz a THz, en regime continu ou impulsionnel. Applications opto-microondes

    Energy Technology Data Exchange (ETDEWEB)

    Lai, N.D.

    2003-07-15

    We explored some new features of single- and dual-frequency solid-state lasers oscillating in continuous-wave or pulsed regimes. First, we have developed some techniques to optimise the characteristics of pulsed lasers. A weak modulation of the pump power made it possible to obtain a stable repetition rate with a relative stability of 10{sup -6}. The pulse duration was continuously controlled from ten nanoseconds to a few hundreds nanoseconds by three different methods: adjustment of the laser beam diameter in the absorber, adjustment of the pump beam diameter in the active medium, and, in particular, the use of forked eigenstates in a two-axis laser. Moreover, the forked eigenstates allows to increase the pulse energy by coherent addition of the pulses. A compact two-frequency Nd:YAG-Cr:YAG laser with a beat note frequency continuously adjustable up to 2,7 GHz was demonstrated. The two-frequency pulses are ideal sources to meet various needs of applications such as the Doppler lidar-radar. Moreover, we show that two-frequency pulses at 1,55 {mu}m can be obtained by using a new c-cut Co:ASL saturable absorber in an Er-Yb:glass laser. These pulses are perfectly adapted to free-space detection systems requiring eye safety. The coherence time of the beat note in these lasers was also studied: it is limited by the pulse duration. A new technique of modulating the pump power of a solid-state laser at frequencies close to its relaxation oscillation frequency was studied and made it possible to generate a beat note coherence from pulse to pulse. Frequency conversion techniques using the nonlinear optical effects make it possible to obtain tunable two-frequency sources in the visible spectrum. Green and red two-frequency pulses were obtained by using different conversion techniques, intra-cavity or extra-cavity. A two-frequency THz source in the red spectrum was also obtained by doubling the frequencies of a two-frequency THz Er-Yb:glass laser using a mixed fan-out PPLN crystal. Applications to the generation of microwaves and submillimeter waves using these two-frequency sources in the visible spectrum are discussed. (author)

  13. Experimental study and modelling of high temperature creep flow and damage behaviour of 9Cr1Mo-NbV steel weldments; Etude experimentale et modelisation, du comportement, de l'endommagement et de la rupture en fluage a haute temperature de joint soudes en acier 9Cr1Mo-NbV

    Energy Technology Data Exchange (ETDEWEB)

    Gaffard, V

    2004-12-15

    Chromium martensitic stainless steels are under development since the 70's with the prospect of using them as structural components in thermal and nuclear power plants. The modified 9Cr1Mo-NbV steel is already used, especially in England and Japan, as a material for structural components in thermal power plants where welding is a commonly used joining technique. New generations of chromium martensitic stainless steels with improved mechanical properties for high pressure and temperature use are currently under development. However, observations of several in-service premature failures of welded components in 9Cr1Mo-NbV steel, outline a strong need for understanding the high temperature creep flow and damage behaviour of 9Cr1Mo-NbV steels and weldments. The present study aimed at experimentally determining and then modelling the high temperature creep flow and damage behaviour of both 9Cr1Mo-NbV steels and weldments (typically in the temperature range from 450 C to 650 C). The base metal was first studied as the reference material. It was especially evidenced that tempered chromium martensitic steels exhibit a change in both creep flow and damage behaviour for long term creep exposure. As a consequence, the classically performed extrapolation of 1,000 hours creep data to 100,000 hours creep lifetime predictions might be very hazardous. Based on experimental observations, a new model, integrating and coupling multiple creep flow and damage mechanisms, was developed in the framework of the mechanics of porous media. It was then successfully used to represent creep flow and damage behaviour of the base metal from high to low stress levels even for complex multiaxial loading conditions. Although the high temperature creep properties of the base metal are quite good, the occurrence of premature failure in weldments in high temperature creep conditions largely focused the attention of the scientific community. The lower creep strength of the weld component was also experimentally confirmed in the present study. The evaluation of creep flow and damage behaviour of the weldment requires two types of investigations, namely, the determination of the effect of welding on creep strength of the material especially in the heat affected zone (HAZ), and the investigation of the effect of the mismatch in creep properties between the weld metal, the base metal and the HAZ. To do so, the microstructure of the weakest HAZ was first reproduced on bulk specimens. These specimens were used to experimentally investigate the creep flow and damage behaviour of the weakest HAZ microstructure. The results of experiments allowed to fit a creep model for the simulated HAZ derived from the one designed for the base metal. The integration of constitutive equations of base metal, weld metal and simulated HAZ in finite element calculations of the heterogeneous weldment allows to study the effect of mismatch on creep properties and finally to predict creep lifetime of 9Cr1Mo-NbV welded components. (author)

  14. Theoretical and experimental study of high strain, high strain rate materials viscoplastic behaviour. Application to Mars 190 steel and tantalum; Etude theorique et experimentale du comportement viscoplastique des materiaux aux grandes deformations et grandes vitesses de deformations. Application a l'acier mars 190 et au tantale

    Energy Technology Data Exchange (ETDEWEB)

    Juanicotena, A

    1998-07-01

    This work enters in the general framework of the study and modelling of metallic materials viscoplastic behaviour in the area of high strain and high strain rate, from 10{sup 4} to 10{sup 5} s{sup -1}. We define a methodology allowing to describe the behaviour of armor steel Mars 190 and tantalum in the initial area. In a first time, the study of visco-plasticity physical mechanisms shows the necessity to take into account some fundamental processes of the plastic deformation. Then, the examination of various constitutive relations allows to select the Preston-Tonks-Wallace model, that notably reproduce the physical phenomenon of the flow stress saturation. In a second part, a mechanical characterization integrating loading direction, strain rate and temperature effects is conducted on the two materials. Moreover, these experimental results allow to calculate associated constants to Preston-Tonks-Wallace, Zerilli-Armstrong and Johnson-Cook models for each material. In a third time, in order to evaluate and to validate these constitutive laws, we conceive and develop an experimental device open to reach the area of study: the expanding spherical shell test. It concerns to impose a free radial expanding to a thin spherical shell by means a shock wave generated by an explosive. By the radial expanding velocity measure, we can determine stress, strain rate and strain applied on the spherical shell at each time. In a four and last part, we evaluate constitutive models out of their optimization area's. This validation is undertaken by comparisons 'experimental results/calculations' with the help of global experiences like expanding spherical shell test and Taylor test. (author)

  15. Experimental study and simulation of the extraction conditions of a multicharged ion beam from an electron cyclotron resonance source; Etude experimentale et simulation des conditions d`extraction d`un faisceau d`ions multicharges d`une source a resonance cyclotronique electronique

    Energy Technology Data Exchange (ETDEWEB)

    Mandin, J.

    1996-12-17

    This thesis concerns the beam extraction studies of ECR Ion Sources for the SPIRAL project at GANIL (France). The optical properties (i.e. the emittances) of the radioactive ion beam production source is a crucial point in this project. We performed emittance measurements with a very high transport efficiency and developed a computer code for simulating the extraction and transport conditions. This simulation takes into account all the parameters acting on the extraction process: the characteristics of the ions and electrons emitted by the plasma, their space and energy distributions, the space charge, the magnetic filed of the source and the accelerating electric field. We explained the evolution of the emittances for two different types of ECR Ion Source. The simulation-experiment comparison showed us that the magnetic field and the intrinsic energy of the ions seem to be the most important parameters for explaining the overall emittance behaviour of the ECRIS. We precise their values and comment them. (author). 530refs.

  16. Experimental studies of X-UV rays by a laser plasma: X-UV strioscopy by means of multilayer mirrors; Etude experimentale de la refraction X-UV par un plasma laser: strioscopie X-UV a l`aide de miroirs multicouches

    Energy Technology Data Exchange (ETDEWEB)

    Lutrin, F

    1996-05-20

    This thesis studies a new instrument -from its conception to the measures interpretation- that analyses electronic density gradient in the super critical transportation area of a laser plasma (0,35 {mu}m). This device, so-called of X-UV Schlieren, is based on the refraction property of a probe beam by an index gradient. Its specificity is the use of the X-UV emission at 13 nm (92 eV) of another laser plasma as X-UV probe. The conception and characterization of this instrument are defined thanks to both the emissivity and reflectivity properties of laser plasmas and the reflectivity properties of multilayers. Within this report are presented strioscopy images, spatially and spectrally resolved of an aluminium plasma from a 3.10{sup 12} W/cm{sup 2} laser flux, probed by a 13 nm wavelength. The device has to be closely aligned so as to obtain good contrast and good spatial resolution. For the first time, the refraction of a X-UV probe beam by a laser plasma is displayed. The experiments show that this refraction is all the more obvious for a gold probe plasma of energy 105 J and an aluminium probed plasma of energy 1 J. According to our plasma hydrodynamic simulation, the detected refraction corresponds to an electronic density gradient of 6,5.10{sup 25} electrons/cm{sup 4} in the two first microns of the sur-critical area. To study the parameters dependence of this gradient in the sur-critical area, several solutions for improving the instrument are produced. (author) 168 refs.

  17. Characterization of domestic wastes incineration clinkers. Experimental study of the dioxines impact on the environment. Program ''industrial wastes'' DRC 01; Caracterisation des machefers d'incineration d'ordures menageres. Etude experimentale de l'impact des dioxines sur l'environnement. Programme ''dechets industriels'' DRC 01

    Energy Technology Data Exchange (ETDEWEB)

    Brazillet, C.; Badreddine, R

    2002-01-15

    Clinkers resulting from domestic wastes incineration are used in road construction since May 1994. A first study realized by the INERIS showed the poor dioxines content in clinkers and their weak transfer in the environment. In order to verify the hypothesis presented in this study, an experimental study controlled different structures using clinkers. It showed a difference between the clinkers used in old structures which reveal a higher dioxines content and the clinkers used in more recent structures which present weak dioxines content. The use of clinkers, even in the case of significant dioxines level, has not a negative impact on the environment taking into account the transfer modes of these substances. (A.L.B.)

  18. Experimental study of the formation of super-heavy compound nuclei in the reaction {sup 58}Fe + {sup 244}Pu {yields} {sup 302} 120; Etude experimentale de la formation de noyaux composes super-lourds dans la reaction {sup 58}Fe + {sup 244}Pu {yields} {sup 302} 120

    Energy Technology Data Exchange (ETDEWEB)

    Amar, N

    2003-11-01

    This work deals with the nuclear mechanisms that take place in the collision of an incident Fe{sup 58} nucleus with a Pu{sup 244} nucleus for an energy that nears that of the Coulomb barrier. The compound nucleus is Z = 120, A 302. We have studied the specificities of the main reaction products and we have taken into account the information conveyed away by the neutrons released in the collision. Measurements have been performed at the U-400 accelerator in Dubna (Russia). 2 detecting systems have been necessary to detect fission fragments and neutrons: the Corset system is made up of 2 telescopes measuring the time of flight of the nuclear fragments and the Demon multi-detector able to draw the energy spectrum of the neutrons detected in coincidence with the fragments. We know that mass asymmetry is no longer a point of difference between fusion-fission and quasi-fission. It seems that fusion-fission fragments have more kinetic energy than quasi-fission fragments. We have made various analysis concerning the neutron emission in order to find the values of temperatures and multiplicities at pre- and post-scission stages with a view to tell fusion-fission events from quasi-fission events. We have deduced that the contribution of fusion-fission events to symmetric partitioning is about 10%. (A.C.)

  19. Experimental study and modelling of competitive adsorption equilibria of aromatics in liquid phase on X and Y faujasites; Etude experimentale et modelisation des equilibres d'adsorption competitive d'aromatiques en phase liquide sur des faujasites X et Y

    Energy Technology Data Exchange (ETDEWEB)

    Tournier, H.

    2000-10-13

    The separation of p-xylene from C{sub 8} aromatics is performed industrially by selective adsorption on zeolitic molecular sieves. The aim of this work is to study and model adsorption equilibria of C{sub 8} and C{sub 10} aromatics on X and Y zeolites. The experimental data are obtained by an entirely automated equipment allowing to work in a large range of temperature (50 deg. C - 250 deg. C). With this equipment, we can follow the evolution of the composition of the liquid phase and determine the composition of the adsorbed phase at equilibrium by a mass balance calculation and with an inert component. Two analytical techniques are used to determine the composition of the liquid phase: (1) a classical method using a gas chromatograph (GC) allowed to measure selectivities in the concentration range (3%-97%) in a component; (2) an original method based on the use and on the measure of {sup 13}C labelled xylenes was developed to investigate the ranges of strongly contrasting concentrations [0-3%] and [97%-100%] in a component, which are representative of high purity domains. Lastly, three thermodynamic models are used to describe the adsorption equilibria: the Langmuir-Freundlich model, the quasi-chemical model and the statistical model. The last model is the more interesting, because it is based on physical considerations. A new statistical model has been developed with taking into account some observations coming from adsorption phenomenon in zeolites. (author)

  20. Theoretical and experimental study of the double ionization by electron impact involving the Auger effect: processes and exchanges interferences; Etude theorique et experimentale de la double ionisation par impact electronique incluant l'effet auger: interferences d'echanges et de processus

    Energy Technology Data Exchange (ETDEWEB)

    Catoire, F

    2006-09-15

    In this work, double ionisation mechanisms of argon by electron impact in which the Auger effect is included have been studied as a function of the incident electron energy. Five and six fold differential cross sections in angle and in energy have been measured and analysed in a coplanar geometry. The efficiency of the apparatus has been improved by the use of a new toroidal analyser. For the first time, the six fold differential cross section in which the Auger electron and the ejected electron with identical kinetic energies (205 eV) are involved, was measured at an incident energy of 956 eV in the case of argon. In the theoretical models developed during this work, the triple continuum is represented by a manifold of coulomb waves describing the interaction of all electrons with the residual ion. Exchange effects between electrons were also included in the models. Comparison between experimental and theoretical results allows to study the relative contribution of the Auger process and the direct double ionisation on the angular dependence five fold differential cross section. In particular, the Auger process contribution seems to become increasingly important as the incident energy is increased.

  1. Experimental study on the influence of charge exchange on the stopping power in the interaction of chlorine with a gas and a deuterium plasma; Etude experimentale de l`influence des echanges de charges sur le pouvoir d`arret dans l`interaction d`ions chlore avec un gaz et un plasma de deuterium

    Energy Technology Data Exchange (ETDEWEB)

    Nectoux, Marie [Inst. de Physique Nucleaire, Paris-11 Univ., 91 - Orsay (France)

    1998-01-06

    This thesis is placed in the context of the physics of energy deposition of a multicharged heavy ion beam in matter at intermediate energies. The experiment gave measurements of energy loss as a function of final charge state for chlorine ions at 1.7 MeV/u in deuterium gas or plasma. In this way, we explore the influence of charge state evolution, depending on experimentally measured capture and ionization cross sections and the electron density of the target, on energy loss. The target is cylindrical and enclosed by two fast valves. The plasma is created in the gas by a discharge, which induces a magnetic perturbation of the beam (lens effect). This effect induces a divergent and misaligned outgoing beam. A simulation including charge state and velocity evolution of the projectile in flight in the magnetic field has been made in order to optimize beam analysis, to reach a precision better than 10{sup -3} in energy measurement. This study led to removal of the target to the `Split Pole`, a refocusing magnetic spectrometer. The first results obtained clearly show the dependence of energy loss on exit charge and especially on its evolution in the target. This is explained in terms of the lengths covered by the projectile in its successive charge states in the target, which depends on target electron density and the medium considered. In plasma, we observed an energy distribution with exit charge twice that observed in gas, because of a strong decrease of charge exchange. A comparison of data obtained in gas with stopping power calculated from Bethe-Bloch-Barkas theory leads to the necessity of including spatial extension of the projectile charge in the theory. (author) 81 refs., 62 figs., 5tabs.

  2. Contribution to the study of copper and copper-arsenic archaeo-metallurgy using light element analysis and experimental fusion; Contribution a l`etude de la paleometallurgie du cuivre et du cuivre-arsenic a partir de l`analyse des elements legers et de fusions experimentales

    Energy Technology Data Exchange (ETDEWEB)

    Papillon, F

    1997-12-31

    The objective of this study is to try a direct reconstruction from ancient artefacts of the elaboration technology used in the dawning copper metallurgy. This word is based on both the light elements analysis and the carry out of the principles of physical metallurgy. However the study of an archaeological artefact necessitates the use of non destructive methods. A main aspect of this work consists in developing the most adequate metallographic technique and the methods for the determination of oxygen and carbon by ion beam analysis. Additionally experimental melting of copper and copper arsenic alloys were carried out in laboratory, under various temperature and atmosphere conditions, and `on the field` in Archeodrome de Beaune, in order to reconstruct part of the prehistorical craftsmanship. The results of measurement are consistent with our general knowledge of oxido-reduction phenomena and the behaviour of copper and copper arsenic alloys s in agreement with the prediction of thermodynamics. The nuclear analysis of three ancient artefacts showed that the oxygen and carbon contents were closer to those of the Archeodrome than those of the laboratory. Further studies of the field should consider all parameters controlling the physical-chemistry of charcoal fire. (author) 96 refs.

  3. Experimental study of high current negative ion sources D{sup -} / H{sup -}. Analysis based on the simulation of the negative ion transport in the plasma source; Etude experimentale de sources a fort courant d`ions negatifs D{sup -} / H{sup -}. Analyse fondee sur la simulation du transport des ions dans le plasma de la source

    Energy Technology Data Exchange (ETDEWEB)

    Riz, D.

    1996-10-30

    In the frame of the development of a neutral beam injection system able to work the ITER tokamak (International Thermonuclear Experimental Reactor), two negative ion sources, Dragon and Kamaboko, have been installed on the MANTIS test bed in Cadarache, and studies in order to extract 20 mA/cm{sup 2} of D{sup -}. The two production modes of negative ions have been investigated: volume production; surface production after cesium injection in the discharge. Experiments have shown that cesium seeding is necessary in order to reach the requested performances for ITER. 20 mA/cm{sup 2} have been extracted from the Kamaboko source for an arc power density of 2.5 kW/liter. Simultaneously, a code called NIETZSCHE has been developed to simulate the negative ions transport in the source plasma, from their birth place to the extraction holes. The ion trajectory is calculated by numerically solving the 3D motion equation, while the atomic processes of destruction, of elastic collisions H{sup -}/H{sup +} and of charge exchange H{sup -}/H{sup 0} are handled at each time step by a Monte Carlo procedure. The code allows to obtain the extraction probability of a negative ion produced at a given location. The calculations performed with NIETZSCHE have allowed to explain several phenomena observed on negative ion sources, such as the isotopic effect H{sup -}/D{sup -} and the influence of the polarisation of the plasma grid and of the magnetic filter on the negative ions current. The code has also shown that, in the type of sources contemplated for ITER, working with large arc power densities (> 1 kW/liter), only negative ions produced in volume at a distance lower that 2 cm from the plasma grid and those produced at the grid surface have a chance of being extracted. (author). 122 refs.

  4. A micro-mechanical analysis and an experimental characterisation of the behavior and the damaging processes of a 16MND5 pressure vessel steel at low temperature; Etude micromecanique et caracterisation experimentale du comportement et de l'endommagement de l'acier de cuve 16MND5 a basses temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Pesci, R

    2004-06-15

    As part of an important experimental and numerical research program launched by Electricite De France on the 16MND5 pressure vessel steel, sequenced and in-situ tensile tests are realized at low temperatures [-196 C;-60 C]. They enable to associate the observation of specimens, the complete cartography of which has been made with a scanning electron microscope (damaging processes, initiation and propagation of microcracks), with the stress states determined by X-ray diffraction, in order to establish relevant criteria. All these measurements enable to supply a two-scale polycrystalline modeling of behavior and damage (Mori-Tanaka/self-consistent) which is developed concurrently with the experimental characterization. This model proves to be a very efficient one, since it correctly reproduces the influence of temperature experimentally defined: the stress state in ferrite remains less important than in bainite (the difference never exceeds 150 MPa), whereas it is much higher in cementite. The heterogeneity of strains and stresses for each crystallographic orientation is well rendered; so is cleavage fracture normal to the {l_brace}100{r_brace} planes in ferrite (planes identified by electron back scattered diffraction during an in-situ tensile test at -150 C), which occurs sooner when temperature decreases, for a constant stress of about 700 MPa in this phase. (author)

  5. Adsorption of Cs{sup +}, Ni{sup 2+} and lanthanides onto a kaolinite and Na-montmorillonite up to 150{sup 0}C: an experimental and modeling study; Adsorption de Cs{sup +}, Ni{sup 2+} et des lanthanides sur une kaolinite et une smectite jusqu'a 150{sup 0}C: etude experimentale et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Tertre, E

    2005-10-15

    The motivation for this study is to assess the temperature effect on the clay minerals sorption properties. Sorption and desorption of Cs{sup +}, Ni{sup 2+} et Ln{sup 3+} onto a montmorillonite and a kaolinite were performed by batch experiments between 25 and 150 C, and in different pH and ionic strengths conditions. Sorption enthalpies varying between 0 and 80 kJ/mol were then calculated. For europium, surface spectroscopic analyses confirmed that the mechanism involved is adsorption, including at 150 C. Moreover, this method allowed us to obtain qualitatively the different adsorption equilibrium occurring during the reaction. An acid/base study of the clay surfaces was performed in order to assess the temperature effect on the surface charge of these minerals. Then, a surface complexation model including edge sites and structural sites was proposed to interpret the acid/base data and the europium sorption data. (author)

  6. Experimental study and kinetic modeling of the thermal degradation of aromatic volatile organic compounds (benzene, toluene and xylene-para) in methane flames; Etude experimentale et modelisation cinetique de la degradation thermique des composes organiques volatils aromatiques benzenes, toluene et para-xylene dans des flammes de methane

    Energy Technology Data Exchange (ETDEWEB)

    Dupont, L.

    2001-02-01

    This study treats of the thermal degradation of a family of aromatic volatile organic compounds (VOCs) in laminar premixed methane flames at low pressure. The experimental influence of benzene, toluene and xylene-para on the structure of a reference methane flame has been studied. The molar fraction profiles of the stable and reactive, aliphatic, aromatic and cyclic species have been established by the coupling of the molecular beam sampling/mass spectroscopy technique with the gas chromatography/mass spectroscopy technique. Temperature profiles have been measured using a covered thermocouple. A detailed kinetic mechanism of oxidation of these compounds in flame conditions has been developed. Different available sub-mechanisms have been used as references: the GDF-Kin 1.0 model for the oxidation of methane and the models of Tan and Franck (1996) and of Lindstedt and Maurice (1996) in the case of benzene and toluene. In the case of para-xylene, a model has been developed because no mechanisms was available in the literature. These different mechanisms have been refined, completed or adjusted by comparing the experimental results with those obtained by kinetic modeling. The complete kinetic mechanism, comprising 156 chemical species involved in 1072 reactions allows to reproduce all the experimental observations in a satisfactory manner. The kinetic analysis of reactions velocity has permitted to determine oxidation kinetic schemes for benzene, toluene, xylene-para and for the cyclopentadienyl radical, main species at the origin of the rupture of the aromatic cycle. Reactions of recombination with the methyl radicals formed during methane oxidation, of the different aromatic or aliphatic radicals created during the oxidation of aromatics, play an important role and lead to the formation of several aromatic pollutants (ethyl-benzene for instance) or aliphatic pollutants (butadiene or penta-diene for instance) in flames. (J.S.)

  7. Experimental and modeling study of the impact of vertical transport processes from the boundary-layer on the variability and the budget of tropospheric ozone; Etude experimentale et numerique de l'influence des processus de transport depuis la couche-limite sur la variabilite et le bilan d'ozone tropospherique

    Energy Technology Data Exchange (ETDEWEB)

    Colette, A

    2005-12-15

    Closing the tropospheric ozone budget requires a better understanding of the role of transport processes from the major reservoirs: the planetary boundary layer and the stratosphere. Case studies lead to the identification of mechanisms involved as well as their efficiency. However, their global impact on the budget must be addressed on a climatological basis. This manuscript is thus divided in two parts. First, we present case studies based on ozone LIDAR measurements performed during the ESCOMPTE campaign. This work consists in a data analysis investigation by means of a hybrid - Lagrangian study involving: global meteorological analyses, Lagrangian particle dispersion computation, and mesoscale, chemistry - transport, and Lagrangian photochemistry modeling. Our aim is to document the amount of observed ozone variability related to transport processes and, when appropriate, to infer the role of tropospheric photochemical production. Second, we propose a climatological analysis of the respective impact of transport from the boundary-layer and from the tropopause region on the tropospheric ozone budget. A multivariate analysis is presented and compared to a trajectography approach. Once validated, this algorithm is applied to the whole database of ozone profiles collected above Europe during the past 30 years in order to discuss the seasonal, geographical and temporal variability of transport processes as well as their impact on the tropospheric ozone budget. The variability of turbulent mixing and its impact on the persistence of tropospheric layers will also be discussed. (author)

  8. Research on the reactions {sup 9}Be ({sup 3}He, 3 {alpha}) and {sup 10}B (d, 3 {alpha}); Contribution a l'etude experimentale des reactions {sup 9}Be ({sup 3}He, 3 {alpha}) et {sup 10}B (d, 3 {alpha})

    Energy Technology Data Exchange (ETDEWEB)

    Thouvenin, P. [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1967-06-15

    For studying these reactions, the detection of the final particles emitted in coincidence in the directions {theta}{sub 1} and {theta}{sub 2}, together with the bi-parametric analysis of the corresponding pulses are used. This method enables us to obtain the orthogonal Dalitz diagrams (E{sub 1}, E{sub 2}). An examination of the spectra obtained shows that the sequential mechanism appears to predominate. The contribution of the purely statistical process is less than 15 per cent of the total spectrum. In the case of {sup 10}B (d, 3 {alpha}), for E{sub d} = 1.5 MeV, 2,66 MeV and 3 MeV, the width of the peak of the first particles emitted, with respect to {sup 8}Be excitations close to 11 MeV, is found to be equal to 2.6 {+-} 0.6 MeV, much less than the width of the 2. excited state observed by {alpha} - {alpha} scattering. The coincidence spectra and the free spectra give an excitation energy of E{sub x} = 2.68 {+-} 0.07 MeV for the first excited state of {sup 8}Be. Some remarks are made concerning the anomalies observed for E{sub d} = 5 MeV and 9 MeV. The excited levels of {sup 8}Be at 13.91 MeV and 7.56 MeV which have been described in the past are not observed. (author) [French] La detection de deux des particules finales emises en cofncidence dans les directions {theta}{sub 1} et {theta}{sub 2}, et l'analyse biparametrique des impulsions correspondantes sont utilisees pour etudier ces reactions. Cette methode nous permet d'obtenir des diagrammes de Dalitz orthogonaux (E{sub 1}, E{sub 2}). L'examen des spectres obtenus montre que le mecanisme sequentiel semble predominant. La contribution du processus purement statistique est inferieure a 15 pour cent du spectre total. Dans le cas de {sup 10}B (d, 3 {alpha}), pour E{sub d} = 1,5 MeV, 2,66 MeV et 3 MeV, la largeur du pic des premieres particules emises relatives a des excitations de {sup 8}Be voisines de 11 MeV, est trouvee egale a 2,6 {+-} 0,6 MeV, tres inferieure a la largeur du 2. etat excite observee a l'aide de la diffusion {alpha} - {alpha}. Les spectres de coincidences et les spectres libres conduisent a une energie d'excitation Ex = 2,68 MeV {+-} 0,07 MeV pour le 1. niveau excite de {sup 8}Be. Quelques remarques sont emises concernant des anomalies observees pour E{sup d} = 5 MeV et 9 MeV. Les niveaux excites de {sup 8}Be a 13,91 MeV et 7,56 MeV, signales par le passe, ne sont pas observes. (auteur)

  9. Experimental and theoretical studies of the VUV emission and absorption spectra of H{sub 2}, HD and D{sub 2} molecules; Etude experimentale et theorique des spectres d'emission et d'absorption VUV des molecules H{sub 2}, D{sub 2} et HD

    Energy Technology Data Exchange (ETDEWEB)

    Roudjane, M

    2007-12-15

    The aim of this thesis is to carry out an experimental study of the absorption and emission spectra of the D{sub 2} and HD isotopes, with high resolution, in the VUV domain and to supplement it by a theoretical study of the excited electronic states involved in the observed transitions. The emission spectra of HD and D{sub 2} are produced by Penning discharge source operating under low pressure and are recorded in the spectral range 78 - 170 nm. The recorded spectra contains more than 20.000 lines. The analysis of the spectrum consists in identifying and assigning the lines to the electronic transitions between energy levels of the molecule. The present analysis is based on our theoretical calculations of the ro-vibrational energy levels of the excited electronic states and the transition probabilities from these states towards the energy levels of the fundamental state. The theoretical results are obtained by resolving the coupled equations between the excited electronic states B{sup 1}{sigma}{sub u}{sup 1}, B'{sup 1}{sigma}{sub u}{sup 1}, C{sup 1}{pi}{sub u}{sup 1} and D{sup 1}{pi}{sub u}{sup 1}, taking into account the nonadiabatic couplings between these states, and they are obtained in the adiabatic approximation for the excited electronic states B''B-bar{sup 1}{sigma}{sub u}{sup +}, D'{sup 1}{pi}{sub u}{sup 1} and D''{sup 1}{pi}{sub u}{sup 1}. The equations are resolved using a modern method based on the discretization variables representation method. In addition, we have carried out a study of the absorption spectra of the HD and D{sub 2} molecules.

  10. Experimental study of kinetic and mechanism of dissolution of apatite structured minerals. Application to the prediction of the long term behavior of an actinides storage host matrix; Etude experimentale de la cinetique et des mecanismes d'alteration de mineraux apatitiques. Application au comportement d'une ceramique de confinement d'actinides mineurs

    Energy Technology Data Exchange (ETDEWEB)

    Chairat, C

    2005-11-15

    The motivation for this study is to assess the potential of using apatite structured ceramics as long-lived actinide storage hosts. To assess their ability to resist aqueous corrosion, the dissolution of natural fluoro-apatite and synthetic Nd-britholite (neodymium is a proxy for the trivalent actinides) was studied. Mineral surfaces were characterized using a combined spectrometric, electrokinetic and potentiometric approach and dissolution rates were measured in closed and open system reactors as a function of solution composition. Experimental results suggest apatitic minerals dissolve via distinct step sequence: 1) fluoride release, 2) release of the calcium situated in the M1, and 3) the simultaneous removal of phosphate and calcium II via the breaking of only Ca-O bonds. TST based rate equations based in this mechanism accurately describe fluoro-apatite and synthetic britholite dissolution rates as a function of solution composition. Nd release rates are limited by precipitation of Nd-rhabdophane. (author)

  11. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter; Etude experimentale de la propagation et du depot d'energie d'electrons rapides dans une cible solide ou comprimee par choc laser: application a l'allumeur rapide

    Energy Technology Data Exchange (ETDEWEB)

    Pisani, F

    2000-02-15

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  12. Thermal stability of the aromatic fraction of Safaniya crude oil (Middle East): experimental study, kinetic scheme by molecular classes and geochemical implications; Stabilite thermique de la fraction aromatique de l'huile brute safaniya (Moyen-Orient): etude experimentale, schema cinetique par classes moleculaires et implications geochimiques

    Energy Technology Data Exchange (ETDEWEB)

    Al Darouich, T.

    2005-07-15

    The thermal evolution of reservoir oils is controlled by the kinetics of cracking reactions. The present work is concerned with the study of the thermal stability of the light aromatic components (C{sub 6}-C{sub 14}) of crude oils under geological conditions. The aim is to predict this stability through a mode l derived from laboratory pyrolyses. The light cut < 250 deg. C of Safaniya crude oil, corresponding to the C{sub 15} components, was obtained by fractionated distillation; pure aromatic fraction was then separated by liquid chromatography. Detailed molecular characterisation of the aromatic fraction was acquired using HPLC, GC and GC/MS. Then, quantified individual aromatic compounds were lumped into six molecular classes: BTXN, methyl-aromatics, alkyl-aromatics, naphthenic-aromatics, indene and sulphur - containing aromatics. Pyrolyses of the aromatic fraction were performed in gold tubes at 100 bars and different temperature/time conditions in a wide range (1 to 93%) of global conversion. Pyrolysis effluents were analysed and lumped into classes. The pyrolysis data were used to elaborate a semi - empirical kinetic scheme of 13 stoichiometric reactions for the primary and secondary cracking of the unstable classes. The scheme kinetic parameters were first estimated, and then numerically optimised, with the constraints of mass balance and hydrogen conservation. A set of pyrolysis experiments was performed at 375 deg.C under high pressures: 400, 800 and 1200 bars. Increasing slowing down in conversion rate with increasing pressure was thus observed compared to experiments at 100 bars. A slight selective effect of pressure on the different aromatic classes of the charge and on the product distribution was evidenced. The extrapolation of the kinetic model to the conditions of Elgin Field (North Sea) showed that pressure effect should shift the thermal cracking of light aromatics to higher temperatures by almost 8 deg. C. (author)

  13. Experimental and theoretical study of bragg-Fresnel optics etched on multilayer structures. Application: lenses for X-Ray imaging; Etude experimentale et theorique d`optiques de bragg-Fresnel gravees sur miroirs interferentiels multicouches. Application: lentilles pour l`imagerie X

    Energy Technology Data Exchange (ETDEWEB)

    Soullie, G.

    1996-10-01

    This work concerns the study of a new type of X-ray focusing optics known as Bragg-Fresnel lenses developed for imaging in the X and X-UV range. These optics, etched on multilayer structure, combine the focusing properties of zone plate with the Bragg reflection of multilayer used like support. Using synchrotron sources and a plasma source produced by a laser, we tested the efficiency and the spatial resolution of these lenses. With a monochromatic beam, we first obtained the image of a object by using the first order diffraction of an elliptical off-axis Bragg-Fresnel lens. By using only one part of a lens, the superposition of different diffraction orders in focal plane can be avoided, thus improving the image contrast. In order to evaluate the chromatic aberrations of these lenses, we have summed on the same image, three exposures at different energies in the band pass of the multilayer. To reduce these kind of aberrations, we used a system composed of two off-axis lenses. To simplify the alignment, we tested an elliptical off-axis lens associated with a lamellar grating. Thus we are able to validate the theoretical approximation of an off-axis Bragg-Fresnel lens to a variable spaced grating. Finally, to show the perturbation brought by the zeroth order, we successively imaged a laser plasma source with a centred and an off-axis elliptical lenses. As with the synchrotron source, a set of images of a test object enabled us to improve the spatial resolution. (author).

  14. Numerical and experimental study of the influence of the operational parameters on the formation mechanisms of oxides of nitrogen during the combustion of mixtures of cellulosic and plastic materials; Etude experimentale et numerique de l'influence des parametres operatoires sur les mecanismes de formation des oxydes d'azote lors de la combustion de melanges de materiaux cellulosiques et plastiques

    Energy Technology Data Exchange (ETDEWEB)

    Andzi Barhe, T.

    2004-10-15

    The current thesis was performed within a collaboration between the Laboratoire de Combustion et de Detonique (LCD of the University of Poitiers) and the Laboratoire de Physique et de Chimie d'Environnement (LPCE) of the University of Ouagadougou. It was financed by Agency for Environment and Energy Management (ADEME). The principle object of this study is the optimisation of the combustion process during the incineration of waste. This optimisation is aimed at the reduction of the polluting emissions, principally CO and NO, during the incineration of cellulosic and plastic materials. It involves the analysis of the influence of the operational parameters on the polluting emissions and the control of reaction mechanisms of formation and reduction of these pollutants during the combustion process. Consequently, the study was performed in two parts: an experimental part and a numerical part. The experimental part was realised using a fixed bed counterflow reactor. This setup simulates the combustion within an industrial waste incinerator. The reactor allows the combustion of a vertical layer of waste mixture (wood, cardboard, PET, polyamide) to be followed. Three model mixtures representative of the makeup of household waste were studied in order to determine the influence of the composition of the waste on the emission of pollutants (CO and NO). The obtained results show that this parameter has a practically negligible influence within the tested parameter range. Consequently the formation of pollutants depends on the operating parameters - the equivalence ratio and the temperature. A numerical study of the influence of these parameters in order to show their impact on the mechanisms of pollutant formation and to determine the chemical mechanisms involved in the formation of oxides of nitrogen. The numerical study was performed with software developed at the LCD. This programme based on a detailed chemical model coupled to a simple physical model. It uses the calculation code CHEMKIN. It permits the simulation of combustion process within the gaseous zone of the fixed bed reactor. The programme is initialized with the results of the analysis of the pyrolysis which had previously been performed at the LCD on the materials which make up the model waste mixture. The pyrolysis products identified during this study are: HCN, NH{sub 3}, NO, NO{sub 2}, CO and light hydrocarbons. The results show that the simulation enables the determination of reactional mechanisms of the formation and reduction of oxides of nitrogen in the three combustion regimes identified during the experimental study. For each of the three regimes, a study of the impact of the combustion parameters on the yield of NO was performed. It can be seen that the response to the parameters is itself heavily dependent on the combustion regime. (author)

  15. Experimental and numerical studies of the effect of plasticity mechanisms on the brittle rupture by cleavage in low alloy steels; Etudes experimentale et numerique de l'effet des mecanismes de plasticite sur la rupture fragile par clivage dans les aciers faiblement allies

    Energy Technology Data Exchange (ETDEWEB)

    Libert, M

    2007-09-15

    It is indispensable to guarantee the integrity of PWR reactor vessels during an accidental running: in this context, the understanding and the modelling of the mechanisms of brittle rupture of steels are decisive elements of the complicated estimation of the service life of reactor vessels. The models of local approach of rupture by cleavage are one of the main tools of anticipation of the tensile strength of low alloy steels. In this work, the effect of the stresses heterogeneities in a local criteria of initiation of cleavage has been taken into account. The results of the microstructure calculations are used for proposing a statistical description of the local stresses distribution evolution. This statistical approach allows to propose a local approach model of the rupture depending both of the mechanical heterogeneities and of the sizes distributions of the defects. The behaviour of the material and its evolution are characterized at the microscopic and macroscopic scales in the temperature range [25 C, -196 C]. Simple tensile tests, velocity and temperature rises tests and toughness tests have been carried out. A micro-mechanical behaviour model describing the plastic behaviour below the transition temperature T{sub a} has been proposed. The behaviour law is based on the deformation mechanisms described in bibliography and identified by an inverse method from mechanical tests. The TEM observations and the characterization of the behaviour thermally activated allow to determine several parameters of the model. Simulations are carried out in order to model the main stress distributions {sigma}{sub 1} in two bainite microstructures corresponding to the elementary volume of the local approach of the rupture. The temperature and the triaxiality effects on the evolutions of the heterogeneities is characterized. A distribution function describing the distribution of the local values of {sigma}{sub 1} in terms of the main and equivalent mean stresses {sigma}{sub 1} and {sigma}{sub m} in the microstructure is proposed. This function is used for formulating a model of rupture local approach integrating the distribution of the critical defects sizes and the distributions of {sigma}{sub 1}. It is shown that in some cases, the dispersion of the local stresses is sufficient to explain the dispersions of the rupture stresses at the scale of the elementary volume. The dispersions of the rupture stresses are in agreement with those given by the Beremin model. The taken into account of the mechanical heterogeneities allows to introduce a dependency of the rupture probability in terms of temperature, of deformation and of triaxiality. (O.M.)

  16. Etudes Asymptotiques en Filtrage Non Lineaire Avec Petit Bruit D’Observation (Asymptotic Studies in Nonlinear Time Filtering with Small Observation Noise)

    Science.gov (United States)

    1990-09-26

    ASYMPTOTIQUES EN FILTRAGE NON LINEAIRE AVEC PETIT BRUIT D’OBSERVATION Soutenue le 26 Septembre 1990 devant le jury compos6 de" M. B. COUPET President Mme...PROVENCE Spdcialitd: MATHEMATIQUES APPLIQUEES par PAULA M. L. P. MILHEIRO de OLIVEIRA Sujet dela thse: E~TUDES ASYMPTOTIQUES EN FILTRAGE NON LINEAIRE ...non lineaire en temps discret avec petit bruit d ’observation FILTRES APPROCHES POUR UN PROBLEME DE FILTRAGE NON LINEAIRE DISCRET AVEC PETIT BRUIT

  17. Etude technico-économique d'un système hybride (aérogénérateur ...

    African Journals Online (AJOL)

    Etude technico-économique d'un système hybride (aérogénérateur et moteur diesel) pour la production d'électricité. ... aspect because the development of the aerogenerators and the diesel engines come under the technical field but also of the economic field, so that the production of electrical energy is viable that is to say ...

  18. The development of a very high stability electrostatic generator (1962); Etude et realisation d'un generateur electrostatique a tres haute stabilite (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Jonckheere, R.E.L. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1962-07-01

    This thesis deals with the study of an electrostatic high voltage generator having a voltage stability of the order of 10{sup -6} per minute. This equipment should be very useful in electron microscopy. The electrostatic generator is studied as a control system element: transfer function, parasitic signals and noise are determined and a mathematical model is proposed. A theoretical study of the open loop transfer function, stability, transient response, voltage stabilization of five different control systems shows which one should be able to fulfill the requirements There follows a detailed study of drift, a description of the actual system and performance data. (author) [French] Cette etude concerne un generateur electrostatique capable de fournir une tres haute tension continue dont la stabilite relative est de l'ordre de 10{sup -6} pendant une minute. Une telle performance rend cet appareillage tres utile en microscopie electronique. La generatrice electrostatique est etudiee en tant qu'element d'un systeme asservi: on determine successivement la fonction de transfert, les perturbations, le bruit de fond et le modele mathematique. L'etude de cinq differents circuits de regulation en ce qui concerne leur fonction de transfert, stabilite, reponse en regime transitoire, attenuation des perturbations, permettra de choisir le systeme qui semble le mieux repondre aux exigences. Viennent ensuite une etude detaillee de la derive, la description de la realisation pratique et les resultats de mesure. (auteur)

  19. A study of the aptitude of soils under natural conditions to retain radiostrontium; Etude de la vocation des sols en place a la retention du radiostrontium

    Energy Technology Data Exchange (ETDEWEB)

    Bovard, P.; Grauby, A. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    Independently of the theoretical study of the propagation of radioactivity in the soil as a result of submersions or of radioactive rain, the authors have studied directly and practically how this radioactivity can vary in the actual soil. To this end a simple, rapid method has been perfected; it makes it possible to maintain for each soil sample the natural parameters (structure, humidity, etc.) without introducing boundary effects. In the laboratory, after charging the soil samples, part of the study of the propagation of radioactivity is done by autoradiography; finally, as a practical application, the study of an atomic site illustrates the methods described. (author) [French] Independamment de l'etude theorique de la propagation de la radioactivite dans le sol a la suite de submersions ou de pluies radioactives, les auteurs ont etudie directement et pratiquement comment pourrait evoluer cette radioactivite dans les sols en place. Pour cela, une methode simple et rapide a ete mise au point; elle permet de conserver pour chaque echantillon de sol, les parametres naturels (structure, humidite, etc...), sans introduire d'effets de paroi. En laboratoire, apres mise en charge des massifs preleves, une partie de l'etude de la propagation des radioelements est realisee par autoradiographie; enfin, une application pratique, l'etude d'un site atomique, illustre l'expose. (auteur)

  20. Experimental contamination of margaritana margaritifera (L) (a Fresh water bivalve) by caesium 137; Contamination experimentale de margaritana margaritifera (L) (bivalve d'eau douce) par le cesium 137

    Energy Technology Data Exchange (ETDEWEB)

    Foulquier, L.; Bovard, P.; Grauby, A. [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1966-07-01

    The hydro biological research carried out in the Radio-Ecology Section has led the authors to study some Margaritana sampling stations situated down-stream from the Monts d'Arree nuclear power station. They describe the preservation and contamination methods used for fixing the {sup 137}Cs concentration factors in the case of Margaritana Margaritifera (L). The results of experiments carried out over a period of one hundred days show that the specific activity of the various organs is stabilized after thirty to thirty-five days. The authors have noticed a relatively low adsorption on the shell through the intermediary of micro-organisms, and a strong and rapid absorption in the soft parts. The concentration factors have values, at equilibrium, of around: 9 for the shell, 300 for all the organs, and 38 for the whole animal. A comparison of these results with work published by other authors makes it possible to draw general conclusions concerning the mechanism of {sup 137}Cs fixation by lamellibranch, as well as their capacity of fixation. (author) [French] Les etudes hydrobiologiques effectuees au sein de la Section de Radio-Ecologie ont amene les auteurs a etudier des stations de prelevement de Margaritana en aval de la Centrale Nucleaire des Monts d'Arree. Ils decrivent les methodes de conservation et de contamination utilisees pour l'etablissement des facteurs de concentration du {sup 137}Cs par Margaritana margaritifera (L). Les resultats des experimentations menees pendant cent jours montrent que les activites specifiques de la coquille et des differents organes se stabilisent au bout de trente a trente-cinq jours. Les auteurs constatent une adsorption relativement faible sur la coquille par l'intermediaire des micro-organismes et une absorption forte et rapide dans les parties molles. Les facteurs de concentration se situent, a l'equilibre, autour de: 9 pour la coquille, 300 pour l'ensemble des organes et 38 si l'on considere

  1. LOS CONOCIMIENTOS EXPERIMENTALES EN LAS PRÁCTICAS EDUCATIVAS DE LOS PARALELOS CON TIEMPO EXTENDIDO BAJO EL PROGRAMA MÁS EDUCACIÓN: UN ESTUDO DE CASO EN DUQUE DE CAXIAS/RJ

    Directory of Open Access Journals (Sweden)

    Sheila Cristina Monteiro Matos

    2012-07-01

    Full Text Available Este estudio tuvo como objetivo analizar cómo se está desarrollando el conocimiento experimental en las prácticas educativas de la Escuela Municipal Visconde de Itaboraí, en el municipio de Duque de Caxias, desde la aplicación del Programa “Más Educación/Más Escuela”. Para ello, se utilizó el método dialéctico impartido por Frigotto, teniendo como método de análisis el estudio de caso. El trabajo de campo se desarrolló a través de entrevistas, observaciones y la investigación de registros. El análisis de datos se realizó mediante análisis de contenido según Bardin. El estudio de la práctica educativa y del conocimiento experimental tuve como referencia las enseñanzas de Tardif sobre el conocimiento docente. En síntesis, podemos decir que los conocimientos experimentales en las prácticas educativas promueven la formación integral, proporcionando un mejor rendimiento académico de los estudiantes, aunque tímidamente, pues la articulación de las materias entre los turnos es un obstáculo importante para la efectividad de las prácticas educativas.

  2. Aproximación al estudio de las estrategias didácticas en ciencias experimentales en formación inicial del profesorado de Educación Secundaria: descripción de una experiencia

    Directory of Open Access Journals (Sweden)

    Natalia Jiménez-Tenorio

    2016-01-01

    Full Text Available Se fundamenta y describe una actividad orientada a la formación inicial de profesores de secundaria de especialidades de ciencias experimentales. La actividad está planteada como intento de aproximación al estudio de distintas estrategias didácticas, más o menos insertas dentro del marco socio-constructivista: “aprendizaje por descubrimiento”, “cambio conceptual”, “enseñanza por investigación entorno a problemas” y “enfoques CTS”. La actividad incluye una serie de estudios de caso (cuatro en total, uno para cada estrategia analizada consistente en supuestos de secuencias de actividades dirigidas a alumnos de educación secundaria obligatoria. Acompañando a los cuatro casos se proporciona un guión de análisis consistente en una serie de preguntas que los alumnos tienen que responder, como forma de orientar el trabajo y de articular el desarrollo de la actividad en su conjunto. La actividad fue ensayada con grupos de alumnos del MAES (Máster de Educación Secundaria de especialidades de “Física y Química” y de “Biología y geología”, y sus resultados expuestos en otro estudio publicado en paralelo a éste.

  3. La conformación del cáncer como objeto científico y problema sanitario en la Argentina: discursos, prácticas experimentales e iniciativas institucionales, 1903-1922

    Directory of Open Access Journals (Sweden)

    José D. Buschini

    2014-06-01

    Full Text Available El trabajo analiza la conformación del cáncer como problema sanitario y como objeto científico en la Argentina en las dos primeras décadas del siglo XX. Se consideran la adquisición y circulación de conocimientos foráneos sobre el tema, el contexto en el que surgieron los primeros desarrollos experimentales, las iniciativas institucionales promovidas desde la profesión médica y el modo en que se logró interesar a las autoridades estatales y a la sociedad civil para darles curso. Se estudia de manera detallada el proceso de creación del Instituto de Medicina Experimental, un centro destinado enteramente al estudio y el tratamiento del cáncer, inaugurado en el año 1922 y que clausura simbólicamente la primera etapa de conformación del cáncer como problema en el país.

  4. Etude thermo-hydraulique de l'ecoulement du moderateur dans le reacteur CANDU-6

    Science.gov (United States)

    Mehdi Zadeh, Foad

    importante, se traduisant par l'accroissement de la puissance du reacteur. Ceci peut avoir des consequences majeures pour la surete nucleaire. Une modelisation CFD (Computational Fluid Dynamics) detaillee tenant compte des effets locaux s'avere donc necessaire. Le but de ce travail de recherche est de modeliser le comportement complexe de l'ecoulement du moderateur au sein de la cuve d'un reacteur nucleaire CANDU-6, notamment a proximite des tubes de calandre. Ces simulations servent a identifier les configurations possibles de l'ecoulement dans la calandre. Cette etude consiste ainsi a formuler des bases theoriques a l'origine des instabilites macroscopiques du moderateur, c.-a-d. des mouvements asymetriques qui peuvent provoquer l'ebullition du moderateur. Le defi du projet est de determiner l'impact de ces configurations de l'ecoulement sur la reactivite du reacteur CANDU-6.

  5. Analysis of heavy oils flows in saturated rocks; Analyse des ecoulements d'huiles lourdes dans les roches saturees

    Energy Technology Data Exchange (ETDEWEB)

    Luc Dormieux; Denis Garnier [Ecole Nationale des Ponts et Chaussees, 6 et 8 avenue Blaise Pascal Cite Descartes - Champs/Marne, 77455 Marne la Vallee Cedex 2, (France); Thierry Yalamas; Elisabeth Bemer; Jean-Francois Nauroy [Institut Francais du Petrole 1 et 4 avenue de Bois-Preau, 92852 Rueil-Malmaison Cedex, (France)

    2005-07-01

    In heavy oil reservoirs, the fluid is a viscous material, possibly nonlinear. In order to describe the flow of such oils in the rock, an extension of Darcy law to non Newtonian fluids is presented. Besides, oil production in this type of reservoir is responsible for rock erosion and the formation of a paste (slurry) made up of a mixture of oil and sand grains is observed. Based on a non linear homogenization technique, a modelling of the constitutive behavior of this slurry is proposed. (authors)

  6. Studies of magnetism with inelastic scattering of cold neutrons; Etudes de magnetisme realisees a l'aide de la diffusion inelastique de neutrons froids

    Energy Technology Data Exchange (ETDEWEB)

    Jacrot, B. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    Inelastic scattering of cold neutrons can be used to study some aspects of magnetism: spins waves, exchange integrals, vicinity of Curie point. After description of the experimental set-up, several experiments, in the fields mentioned above, are analysed. (author) [French] La technique de diffusion inelastique des neutrons froids est utilisee pour etudier certains aspects du magnetisme: ondes de spins, integrales d'echange, etude au voisinage du point de Curie, etc. Apres une description de l'appareillage, on analyse diverses experiences effectuees dans les domaines enumeres plus haut. (auteur)

  7. Evaluation of experimental vaccines for bovine viral diarrhea in bovines, ovines and guinea pigs Evaluación de vacunas experimentales para la diarrea viral bovina en bovinos, ovinos y cobayos

    Directory of Open Access Journals (Sweden)

    F. Fernández

    2009-06-01

    Full Text Available The bovine viral diarrhea virus (BVDV infection control should be based on elimination of persistently infected animals and on immunization through vaccination, to prevent fetal infection. However, the efficacy of inactivated BVDV vaccines is variable due to its low immunogenicity. This study evaluated the humoral immune response against homologous and heterologous strains of 7 inactivated BVDV vaccines, in bovines and two experimental models (ovine and guinea pig which might be used to test candidate vaccines. Vaccines formulated with BVDV Singer, Oregon, NADL, and multivalent, induced seroconversion in the three animal models studied, reaching antibody titres higher than 2. Vaccine containing 125C -genotype 2- only induced a low antibody response in ovine, while VS-115 NCP vaccine was not immunogenic. Furthermore, bovine sera at 60 dpv presented homologous as well as heterologous antibody response, indicating a high degree of cross-reactivity among the strains studied. However, when bovine sera were tested against the Argentine field strain 00-693, they showed the lowest levels of cross-reactivity, suggesting the need of continued surveillance to identify and characterize emerging field BVDV strains. Finally, optimal correlations between bovine-ovine and bovine-guinea pig models were observed, indicating that two alternative species could replace bovines when testing the immunogenicity of BVDV candidate vaccines.El control del virus de la diarrea viral bovina (VDVB se basa en la eliminación de animales persistentemente infectados, y la inmunización de hembras para prevenir infecciones fetales. La eficiencia de estas vacunas es variable por su baja inmunogenicidad. Se evaluó la respuesta inmune humoral contra virus homólogos y heterólogos de 7 vacunas experimentales inactivadas del VDVB en bovinos y en dos modelos experimentales (ovinos y cobayos. Las vacunas conteniendo VDVB Singer, Oregon, NADL y polivalentes indujeron seroconversión en

  8. Variabilidad de las proporciones molares en poblaciones humanas: un abordaje empleando modelos del desarrollo y experimentales / Variability of molar proportions in human populations: insights from developmental models and experiments in mice

    Directory of Open Access Journals (Sweden)

    Lucas A. D´Addona

    2016-03-01

    Full Text Available Los datos sobre la variación dental interpoblacional y sobre los mecanismos que regulan el desarrollo dental aportados por estudios experimentales aún no han sido integrados en el contexto de investigaciones antropobiológicas. En este sentido, el presente trabajo se propone: a evaluar la consistencia entre la variación de las proporciones molares en poblaciones humanas que exhiben gran variación en el tamaño dental con las predicciones derivadas de un modelo de desarrollo dental de cascada inhibitoria, y b analizar el efecto de los factores sistémicos que controlan el crecimiento del organismo sobre las proporciones de los molares inferiores empleando cepas de Mus musculus. Se calcularon las áreas de los molares inferiores mediante los diámetros bucolingual y mesiodistal. La variación interpoblacional en las proporciones M2/M1 y M3/M1 fue concordante con las expectativas derivadas del modelo y la mayoría de los grupos exhibieron una tendencia a la reducción del tamaño en sentido antero-posterior. Asimismo, se observó una asociación significativa y positiva entre el área molar total y las proporciones molares. En los modelos experimentales la alteración del crecimiento por factores sistémicos (subnutrición proteica y reducción de la hormona de crecimiento resultó en la disminución del área molar total y cambios en las proporciones molares. Estos últimos, consistentes con el incremento del efecto inhibitorio en sentido antero-posterior. En conjunto, los resultados sugieren que la modificación de los factores sistémicos que regulan el área molar total podría conducir a cambios en la proporción de activadores-inhibidores y contribuir a la diferenciación interpoblacional en las proporciones molares. Palabras clave: Modelo de cascada inhibitoria; tamaño dental; aproximación experimental y comparativa Data on dental variation among human populations and the mechanisms regulating tooth development elucidated by

  9. Invasive Fusarium infections: a retrospective survey of 31 cases. The French 'Groupe d'Etudes des Mycoses Opportunistes' GEMO.

    Science.gov (United States)

    Hennequin, C; Lavarde, V; Poirot, J L; Rabodonirina, M; Datry, A; Aractingi, S; Dupouy-Camet, J; Caillot, D; Grange, F; Kures, L; Morin, O; Lebeau, B; Bretagne, S; Guigen, C; Basset, D; Grillot, R

    1997-01-01

    A retrospective study was conducted in France to investigate Fusarium infections which are now recognized as emerging opportunistic infections. The clinical and mycological findings for 31 cases diagnosed between 1984 and 1993 by members of the French Groupe d'Etudes des Mycoses Opportunistes were analysed. All suffered from haematological disease, most often acute leucaemia (n = 19). Twenty-two had received cytostatic chemotherapy and ten had undergone bone marrow transplantation. Prolonged aplasia and pancytopenia were present in 18 and 11 patients, respectively. Skin (61%) and blood (42%) were the sites most frequently involved. Fusarium solani (n = 7), Fusarium oxysporum (n = 7), Fusarium verticilloides (n = 7) were the species most frequently isolated. Nine antifungal treatments were used, associated with colony-stimulating factors in five cases. None was unambiguously superior to all the others. The overall mortality was 51.6% with a specific mortality > or = 25.8%. The disseminated form of the infection was associated with poor prognosis (P infections. As prognosis is closely correlated with neutrophil recovery, the promising results obtained with the use of colony-stimulating factors should be further evaluated.

  10. Cognitive decline is associated with systemic oxidative stress: the EVA study. Etude du Vieillissement Artériel.

    Science.gov (United States)

    Berr, C; Balansard, B; Arnaud, J; Roussel, A M; Alpérovitch, A

    2000-10-01

    To determine whether systemic oxidative stress status is associated with cognitive decline. A longitudinal population-based study. A cohort study of older subjects in Nantes, France. A total of 1166 high cognitive functioning subjects aged 60 to 70 in the Etude du Vieillissement Arteriel (EVA) cohort with a 4 year follow-up. Subjects completed a baseline interview and a global cognitive test (Mini-Mental Status Examination (MMSE)). Blood samples were obtained at baseline to determine plasma levels of selenium, carotenoids, thiobarbituric acid reactant substances (TBARS), an indicator of lipoperoxidation, and red blood cell vitamin E. Risk of cognitive decline, defined as a loss of 3 points in MMSE score between baseline and the 4 year follow-up, was assessed by oxidative stress level. Subjects with the highest levels of TBARS show an increased risk of cognitive decline (adjusted odds ratio (OR) = 2.25; confidence interval (CI) 95% = 1.26-4.02). This result is reinforced in the lower antioxidant status subgroup. Subjects with low levels of selenium have an increased risk of cognitive decline (OR = 1.58; CI 95% = 1.08-2.31) after adjustment for various confounding factors. These results suggest that increased levels of oxidative stress and/or antioxidant deficiencies may pose risk factors for cognitive decline. The direct implication of oxidative stress in vascular and neurodegenerative mechanisms that lead to cognitive impairment should be further explored.

  11. Research trends in radiobiology since 40 years. a new approach: the enzymatic repair function of DNA, internal factor in evolution of biological systems under irradiation; Etude des tendances des recherches en radiologie depuis 40 ans. Une nouvelle voie de recherche: la fonction de reparation enzymatique de l'ADN, facteur interne d'evolution des systemes biologiques sous rayonnement

    Energy Technology Data Exchange (ETDEWEB)

    Mouton, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    . Il y a moins d'une generation, l'on croyait encore que les effets des rayonnements sur les systemes vivants etaient des effets directs, immediats, irreparables et definitifs. Depuis lors, on s'est rendu compte que les radiolesions pouvaient resulter d'effets indirects, etre tardives, reparables, et le plus souvent modifiables par des traitements chimiques ou biochimiques ad hoc. Cependant, la percee decisive en radiobiologie se situe entre 1962 et 1964, avec la decouverte que la cellule possede un mecanisme de defense active vis-a-vis de tout ce qui peut porter atteinte a l'integrite du patrimoine genetique inscrit dans la structure meme de l'ADN. L'existence d'une quatrieme fonction de l'ADN, celle d'auto-reparation, par voie enzymatique sous controle genetique, apporte enfin a la radiobiologie la base biologique moleculaire qui lui manquait pour sortir de la nuit 'phenomenologique' ou elle s'etait enfoncee apres l'abandon de la generalisation de la theorie de Lea, faute de preuve experimentale. Dans la seconde partie, cette fois prospective, de l'etude l'auteur tente une synthese elargie en considerant le role que peut jouer cette fonction de reparation de l'ADN non seulement du point de vue de la survie des systemes biologiques irradies en presence ou non d'agents modificateurs de dose ou mutagenes, mais aussi de celui de l'evolution naturelle ou artificielle de ces systemes sous rayonnement. Les donnees les plus recentes de la litterature sont en accord avec ce qui ne constitue encore qu'une hypothese generale de recherche. Des travaux portant sur les caracteres phenotypiques et genotypiques lies a l'acquisition de radioresistance gamma et UV, chez 'Escherichia coli K12', ont ete entrepris par l'auteur, en collaboration avec O. Tremeau en vue d'apporter une contribution experimentale nouvelle a cet egard. (auteur)

  12. Etude des phenomenes dynamiques ultrarapides et des caracteristiques impulsionnelles d'emission terahertz du supraconducteur YBCO

    Science.gov (United States)

    Savard, Stephane

    Les premieres etudes d'antennes a base de supraconducteurs a haute temperature critique emettant une impulsion electromagnetique dont le contenu en frequence se situe dans le domaine terahertz remontent a 1996. Une antenne supraconductrice est formee d'un micro-pont d'une couche mince supraconductrice sur lequel un courant continu est applique. Un faisceau laser dans le visible est focalise sur le micro-pont et place le supraconducteur dans un etat hors-equilibre ou des paires sont brisees. Grace a la relaxation des quasiparticules en surplus et eventuellement de la reformation des paires supraconductrices, nous pouvons etudier la nature de la supraconductivite. L'analyse de la cinetique temporelle du champ electromagnetique emis par une telle antenne terahertz supraconductrice s'est averee utile pour decrire qualitativement les caracteristiques de celle-ci en fonction des parametres d'operation tels que le courant applique, la temperature et la puissance d'excitation. La comprehension de l'etat hors-equilibre est la cle pour comprendre le fonctionnement des antennes terahertz supraconductrices a haute temperature critique. Dans le but de comprendre ultimement cet etat hors-equilibre, nous avions besoin d'une methode et d'un modele pour extraire de facon plus systematique les proprietes intrinseques du materiau qui compose l'antenne terahertz a partir des caracteristiques d'emission de celle-ci. Nous avons developpe une procedure pour calibrer le spectrometre dans le domaine temporel en utilisant des antennes terahertz de GaAs bombarde aux protons H+ comme emetteur et detecteur. Une fois le montage calibre, nous y avons insere une antenne emettrice dipolaire de YBa 2Cu3O7-delta . Un modele avec des fonctions exponentielles de montee et de descente du signal est utilise pour lisser le spectre du champ electromagnetique de l'antenne de YBa 2Cu3O7-delta, ce qui nous permet d'extraire les proprietes intrinseques de ce dernier. Pour confirmer la validite du modele

  13. Castor and Pollux - shielded cells for studying fuel treatment processes; Castor et Pollux chaines blindees d'etudes de procedes de traitement de combustibles

    Energy Technology Data Exchange (ETDEWEB)

    Faudot, G.; Bathellier, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1969-07-01

    CASTOR and POLLUX, two alpha, beta, gamma cells are described in the present paper. They are located in the CEN at Fontenay-aux-Roses (France). They are designed for improvement studies of the various aqueous separation processes used in irradiated fuels reprocessing plants. Located in the same air-tight steel encasement, they arc inter-connected by a pneumatic transfer. These two cells have a similar in-line conception and they include: a gamma shielding in lead of 10 cm of thickness; an inner air-tight box, made with stainless steel and plexiglas, is maintained in lowering in comparison to room pressure. Eleven Hobson model seven master-slave manipulators allow inner manipulations. Then the inner equipment is described briefly. (author) [French] Le present document decrit les cellules alpha, beta, gamma CASTOR et POLLUX edifiees au Centre d'Etudes Nucleaires de Fontenay-aux-Roses. Elles sont destinees aux etudes visant a l'amelioration des procedes de separation par voie aqueuse utilises dans les usines de retraitement des combustibles irradies. Ces deux chaines, implantees dans le meme caisson et reliees par convoyeur pneumatique, sont de conception identique et comprennent: une protection biologique constituee par 10 cm d'epaisseur de plomb; une enceinte interieure etanche alpha, en acier inoxidable et plexiglas, maintenue en depression. Des telemanipulateurs Hobson, modele 7, permettent les manipulations interieures. On decrit ensuite brievement les installations annexes. (auteur)

  14. Preliminary study of the preparation of uranium 232 by irradiation of protactinium 231; Etude preliminaire a la preparation d'uranium 232 par irradiation de protactinium 231

    Energy Technology Data Exchange (ETDEWEB)

    Guillot, Ph. [Commissariat a l' Energie Atomique, Fontenay aux Roses (France). Centre d' Etudes Nucleaires

    1965-07-01

    A bibliography about preparation of uranium 232 is done. This even-even isotope of uranium is suitable for radioactive tracer, neutron source through {alpha},n reaction and heat source applications. The irradiation of protactinium 231, the chemical separation and the purification of uranium are studied. (author) [French] Une etude bibliographique de la preparation d'uranium 232 a ete effectuee. Cet isotope pair-pair de l'uranium peut etre utilise en tant que traceur, source d'energie et source de neutrons, lorsqu'il est melange a un element leger tel le beryllium. Une etude du taux de formation des isotopes produits, lors de l'irradiation du protactinium 231 - une des manieres d'obtenir l'uranium 232 - a ete faite a l'aide d'un programme passe sur ordinateur. Les problemes poses par la separation chimique et la purification de l'uranium ont ete egalement envisages dans ce rapport. (auteur)

  15. Potenciación de los aspectos prácticos en la enseñanza de disciplinas experimentales mediante la utilización de las nuevas tecnologías de la información y de la comunicación

    OpenAIRE

    Rodríguez Gonzalo, Encarnación; Nogal Sánchez, Miguel

    2010-01-01

    El proyecto estaba dirigido a potenciar el uso de nuevas tecnologías en la docencia de disciplinas experimentales. Se centra en la asignatura Técnicas Instrumentales Básicas, asignatura de carácter básico, correspondiente al 1º curso del Grado en Biotecnología de la Universidad de Salamanca, que se impartía por primera vez el presente curso 2009-2010. Esta asignatura es eminentemente práctica, que trata de dar al alumno una visión general tanto de los fundamentos básicos como de la aplicabili...

  16. Etude energetique et modelisation d'un Systeme Hybride Eolien-Diesel avec stockage d'Air Comprime (SHEDAC)

    Science.gov (United States)

    Martinez, Nicolas

    Actuellement le Canada et plus specialement le Quebec, comptent une multitude de sites isoles dont !'electrification est assuree essentiellement par des generatrices diesel a cause, principalement, de l'eloignement du reseau central de disuibution electrique. Bien que consideree comme une source fiable et continue, 1 'utilisation des generatrices diesel devient de plus en plus problematique d'un point de vue energetique, economique et environnemental. Dans le but d'y resoudre et de proposer une methode d'approvisionnement plus performante, mains onereuse et plus respectueuse de l'environnement, l'usage des energies renouvelables est devenu indispensable. Differents travaux ont alors demontre que le couplage de ces energies avec des generauices diesel, formant des systemes hybrides, semble etre une des meilleures solutions. Parmi elles, le systeme hybride eolien-diesel avec stockage par air comprime (SHEDAC) se presente comme une configuration optimale pour 1 'electrification des sites isoles. En effet, differentes etudes ont permis de mettre en avant l'efficacite du stockage par air comprime, par rapport a d'autres technologies de stockage, en complement d'un systeme hybride eolien-diesel. Plus precisement, ce systeme se compose de sous-systemes qui sont: des eoliennes, des generatrices diesel et une chaine de compression et de stockage d'air comprime qui est ensuite utilisee pour suralimenter les generatrices. Ce processus permet ainsi de reduire Ia consommation en carburant tout en agrandissant la part d'energie renouvelable dans Ia production electrique. A ce jour, divers travaux de recherche ont pennis de demontrer I' efficacite d 'un tel systeme et de presenter une variete de configurations possibles. A travers ce memoire, un logiciel de dimensionnement energetique y est elabore dans le but d'unifom1iser !'approche energetique de cette technologie. Cet outil se veut etre une innovation dans le domaine puisqu'il est actuellement impossible de dimensionner un

  17. ESTUDIO DE SECUENCIAS DE TALLA LÍTICA A TRAVÉS DE MODELOS EXPERIMENTALES EN ROCAS SILÍCEAS DEL CENTRO DE ARGENTINA (Study of lithic carving sequences through experimental models in siliceous rocks of central Argentina

    Directory of Open Access Journals (Sweden)

    Eduardo Pautassi

    2012-10-01

    Full Text Available La evidencia arqueológica dejada por los grupos humanos que habitaron el centro de Argentina (provincias de Córdoba y San Luis, desde las primeras ocupaciones hasta momentos previos a la conquista española, pone de manifiesto que estas poblaciones desarrollaron diversas estrategias y adaptaciones a lo largo del tiempo. Una de estas estrategias es la producción de artefactos líticos. En este trabajo, se aborda el estudio de las secuencias de reducción de clastos y de manufactura de bifaces experimentales aplicando la metodología de análisis «no tipológico» para el estudio de los desechos de talla. Estas experiencias fueron realizadas como resultado del análisis de la tecnología lítica de sitios arqueológicos ubicados en la localidad arqueológica de Estancia La Suiza, San Luis. La finalidad de este trabajo es comparar ciertos atributos de las lascas producto de la experimentación para diferenciar tipos de actividades de talla. Realizar esta propuesta nos permite presentar en otra oportunidad la comparación con el registro arqueológico, e intentar dilucidar cómo fueron los diferentes momentos en el proceso de talla. ENGLISH: The archaeological evidence left by the humans who occupied the center of Argentina (comprising the present territory of the provinces of Cordoba and San Luis, Argentina, from the earliest settlements until the moments before the Spanish conquest, shows that these populations developed different strategies and adaptations to the environment over time. One such strategy is the production of lithic artifacts. This contribution specifically addresses the study of sequence of cores and reducing manufacturing bifaces by applying the methodology of the “non-typological” analysis to the study of debitage. These experiments were conducted as a result of the analysis of the lithic technology of archaeological sites located at the archaeological locality of Estancia La Suiza, in San Luis province. The purpose of

  18. Study of the stopping power of various filters; Etude du pouvoir d'arret de differents filtres

    Energy Technology Data Exchange (ETDEWEB)

    Madelaine, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The first part is devoted to a study of aerosols obtained from the combustion of various smoke-producing compounds. A trial aerosol of which the size distribution is the closest possible to that of atmospheric dusts has been defined. The efficiency of various filters has been determined for successive increments of the dimensions and not for the whole range of its diameter distribution. The variation in the efficiency of the filtering layers as a function of the filtering speed and particle size has been studied for aerosols having particle diameters of over 0.3 {mu}. The second part describes an original method for measuring the efficiency of filters for ultra-fine particles (under 0.1 {mu}) using the fixation properties of radioactive atoms resulting from the decay of thoron. (author) [French] La premiere partie est consacree a l'etude des aerosols obtenus a partir de la combustion de divers types de fumigenes. Un aerosol d'essai, dont la repartition granulometrique se rapproche le plus possible des poussieres atmospheriques a ete defini. L'efficacite de plusieurs filtres a ete determinee pour des tranches successives de dimension et non pour l'aerosol pris dans sa totalite. La variation de l'efficacite des couches filtrantes en fonction de la taille des particules et de la vitesse de filtration a ete examinee pour des aerosols superieurs a 0,3 {mu}. La seconde partie decrit une methode originale permettant de mesurer l'efficacite des filtres pour des particules ultrafines (inferieures a 0,1 {mu}) en utilisant la propriete de fixation des atomes radioactifs des descendants du thoron. (auteur)

  19. Systematic study of plasma and serum proteins in the pig; Etude systematique des proteines plasmatiques et seriques du porc

    Energy Technology Data Exchange (ETDEWEB)

    Daburon, F.; Nizza, P.; Hatchikian, C.; Schmidt, J.-P. [Commissariat a l' Energie Atomique (France)

    1966-07-01

    This work has been carried out in the framework of the determination of the physiological constants of a normal pig. The aim was to study the serum and plasma proteins of this animal species, the ultimate object being to discover whether the qualitative and quantitative changes in these proteins can make a significant contribution to the establishment of a biological dosimetry for irradiated pigs. The serum and plasma from a normal pig were analyzed first by various simple electrophoretic methods and then by immuno-electrophoresis. As a result of the particular characteristics of pig serum we have gradually been led to make numerous modifications to the techniques used for human serums or for those of small laboratory animals. Much careful work and patience were required in order to obtain reproducible results. (authors) [French] Ce travail se situe dans le cadre de la determination des constantes physiologiques du porc normal. il s'agissait de proceder a l'etude des proteines seriques et plasmatiques de cette espece animale, le but ulterieur etant de savoir si les modifications qualitatives et quantitatives de ces proteines pourront representer une contribution valable a l'etablissement d'une dosimetrie biologique chez le porc irradie. Le serum et le plasma du porc normal ont ete analyses d'abord par diverses methodes electrophoretiques simples puis par immunoelectrophorese. Les caracteristiques particulieres du serum de porc nous ont conduits a apporter progressivement de nombreuses modifications aux techniques utilisees pour des serums humains ou de petits animaux de laboratoire. L'obtention de resultats reproductible a exige beaucoup de patience et de minutie. (auteurs)

  20. Recent research on the pharmaceutical checking of radioelements (1961); Etudes recentes sur le controle pharmaceutique des radioelements (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Y.; Ingrand, J. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    Checking on radioactive preparations for medical use is complicated by difficulties due to the radioactivity, the instability and the methods of using these solutions. In effect it is necessary, in order to draw up a practicable set of rules governing such checks, to know both the method of preparation and the properties of the radioelement, as well as special and often contradictory features of its use. These tests fall into three categories: physical, chemical and biological. Preparations of chromium 51, iron 59 and arsenic 76 have been dealt with in recent studies. In each case special tests were necessary, and these will be described in this paper. The practice of these tests is of twofold interest: firstly they provide a maximum guarantee to the user, and secondly they guide the chemist in his manipulations, immediately and thoroughly. (author) [French] Le controle des preparations radioactives a usage medical est complexe par suite des difficultees dues a la radioactivite, a l'instabilite et aux modalites d'utilisation de ces solutions. En effet, l'etablissement justifie d'un protocole de controle necessite la connaissance aussi bien du mode de preparation, que des proprietes du radioelement et des particularites parfois contradictoires de son emploi. Ces controles sont de trois ordres physiques, chimiques, biologiques. Des etudes recentes ont porte sur des preparations de chrome 51, de fer 59, d'arsenic 76. Dans chaque cas, il est apparu necessaire de pratiquer des controles particuliers qui seront exposes dans la communication. La pratique de ces derniers presente un double interet; d'une part, ils assurent a l'utilisateur un maximum de garantie, d'autre part, ils orientent le chimiste dans ses mises au point, immediatement et de facon approfondie. (auteur)

  1. Effets Seebeck et Nernst dans les cuprates: Etude de la reconstruction de la surface de Fermi sous champ magnetique intense

    Science.gov (United States)

    Laliberte, Francis

    2010-06-01

    Ce memoire presente des mesures de transport thermoelectrique, les effets Seebeck et Nernst, dans une serie d'echantillons de supraconducteurs a haute temperature critique. Des resultats obtenus recemment au Laboratoire National des Champs Magnetiques Intenses a Grenoble sur La1.7Eu0.2Sr0.1 CuO4, La1.675Eu0.2Sr0.125CuO 4, La1.64Eu0.2Sr0.16CuO4, La1.74Eu0.1Sr0.16CuO4 et La 1.4Nd0.4Sr0.2CuO4 sont analyses. Une attention particuliere est accordee aux equations de la theorie semi-classique du transport et leur validite est verifiee. La procedure experimentale et les materiaux utilises pour concevoir les montages de mesures sont expliques en detail. Enfin, un chapitre est dedie a l'explication et l'interpretation des resultats de transport thermoelectrique sur YBa2Cu3O6+delta publies au cours de l'hiver 2010 dans les revues Nature et Physical Review Letters. Les donnees d'effet Seebeck dans les echantillons de La 1.8-x,Eu0.2SrxCuO 4, ou un changement de signe est observe, permettent de conclure a la presence d'une poche d'electrons dans la surface de Fermi qui domine le transport a basse temperature dans la region sous-dopee du diagramme de phase. Cette conclusion est similaire a celle obtenue par des mesures d'effet Hall dans YBa 2Cu3O6+delta et elle cadre bien dans un scenario de reconstruction de la surface de Fermi. Les donnees d'effet Nernst recueillies indiquent que la contribution des fluctuations supraconductrices est limitee a un modeste intervalle de temperature au-dessus de la temperature critique.

  2. Reconstruction de la surface de Fermi dans l'etat normal d'un supraconducteur a haute Tc: Une etude du transport electrique en champ magnetique intense

    Science.gov (United States)

    Le Boeuf, David

    Des mesures de resistance longitudinale et de resistance de Hall en champ magnetique intense transverse (perpendiculaire aux plans CuO2) ont ete effectuees au sein de monocristaux de YBa2Cu3Oy (YBCO) demacles, ordonnes et de grande purete, afin d'etudier l'etat fondamental des supraconducteurs a haute Tc dans le regime sous-dope. Cette etude a ete realisee en fonction du dopage et de l'orientation du courant d'excitation J par rapport a l'axe orthorhombique b de la structure cristalline. Les mesures en champ magnetique intense revelent par suppression de la supraconductivite des oscillations magnetiques des resistances longitudinale et de Hall dans YBa2Cu 3O6.51 et YBa2Cu4O8. La conformite du comportement de ces oscillations quantiques au formalisme de Lifshitz-Kosevich, apporte la preuve de l'existence d'une surface de Fermi fermee a caractere quasi-2D, abritant des quasiparticules coherentes respectant la statistique de Fermi-Dirac, dans la phase pseudogap d'YBCO. La faible frequence des oscillations quantiques, combinee avec l'etude de la partie monotone de la resistance de Hall en fonction de la temperature indique que la surface de Fermi d'YBCO sous-dope comprend une petite poche de Fermi occupee par des porteurs de charge negative. Cette particularite de la surface de Fermi dans le regime sous-dope incompatible avec les calculs de structure de bande est en fort contraste avec la structure electronique presente dans le regime surdope. Cette observation implique ainsi l'existence d'un point critique quantique dans le diagramme de phase d'YBCO, au voisinage duquel la surface de Fermi doit subir une reconstruction induite par l'etablissement d'une brisure de la symetrie de translation du reseau cristallin sous-jacent. Enfin, l'etude en fonction du dopage de la resistance de Hall et de la resistance longitudinale en champ magnetique intense suggere qu'un ordre du type onde de densite (DW) est responsable de la reconstruction de la surface de Fermi. L'analogie de

  3. Contribution to the study of the stability of water-cooled reactors; Contribution a l'etude de la stabilite des reacteurs refroidis par de l'eau

    Energy Technology Data Exchange (ETDEWEB)

    Coudert, C. [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1969-06-01

    This work is devoted to the study of the stability of reactors cooled by water subjected only to natural convection. It is made up of two parts, a theoretical study and experimental work, each of these parts being devoted to a consideration of linear and non-linear conditions: - calculation of the transfer function of the reactor using neutronic and hydrodynamic linear equations with the determination of the instability threshold; - demonstration of the existence of the limiting oscillation cycle in the case of a linear feedback using MALKIN'S method; - measurement and interpretation of the reactor's transfer functions and of the hydrodynamic transfer functions; and - analysis of the noise due to boiling. (author) [French] Dans ce travail on etudie la stabilite des piles refroidies par de l'eau circulant en convection naturelle. Cette etude se divise en deux parties: un travail theorique et un travail experimental, chacune de ces parties comportant une etude lineaire et une etude non-lineaire: - calcul de la fonction de transfert du reacteur a partir des equations lineaires de la neutronique et de l'hydrodynamique avec determination du seuil d'instabilite; - demonstration de l'existence du cycle limite des oscillations dans le cas d'une retroaction lineaire en utilisant la methode de MALKIN; - mesure et interpretation de la fonction de transfert du reacteur et des fonctions de transfert hydrodynamiques; et - analyse du bruit d'ebullition. (auteur)

  4. The study of some thiazinic and indaminic dye syntheses induced by ionising radiation; Etude de quelques syntheses de colorants thianziniques et indaminiques amorcees par les rayonnements ionisants

    Energy Technology Data Exchange (ETDEWEB)

    Balestic, S. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-03-15

    With a view to finding some radiochemical reactions applicable on an industrial scale for evaluating the radioactive waste from nuclear reactors, a systematic study was made of the radiochemical synthesis of thiazinic dyes such as methylene blue and Lauths' violet, on which the first tests were carried out in 1954. The first part of the study concerned the identification and the dosage, during radiolysis, of dyes by means of their absorption spectra after separation from the reaction medium by adsorption chromatography or ion-exchange; other radiolysis products such as ammonium chloride and hydrogen peroxide were also identified. During a later stage by systematically varying the physico-chemical parameters it was possible to determine the most favourable conditions for radio-synthesis; the maximum radiochemical yields obtained had the following values: G (Lauths' violet) 1,65; G (Methylene blue) = 1,75. Furthermore, the study of the influence of variously substituted aminated products on the radiochemical yield showed the possibility of synthesising Bindsehedlers green and Wursters blue by radiochemical methods. Finally the discovery of a fundamental intermediate product, Wursters red, together with the kinetic study of the chemical synthesis of methylene blue made it possible to determine the main stages of the reaction mechanism and to decide which of these stages could be attributed to ionising radiations in the case of the radiochemical synthesis. (author) [French] Dans le but de trouver des reactions radiochimiques susceptibles d'une application industrielle pour valoriser les dechets radioactifs provenant des reacteurs nucleaires, il a ete entrepris une etude systematique de la synthese radiochimique des colorants thiazimiques tels que le Bleu de Methylene et le Violet de Lauth dont les premiers essais ont ete effectues par Loiseleur en 1954. La premiere partie de l'etude a porte sur l'identification et le dosage des colorants formes

  5. Magnetic study of solid uranium-fluorine complexes; Contribution a l'etude magnetique de composes fluores solides de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Dianoux, A.J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-06-01

    A study of the magnetic susceptibility of uranium V fluorine complexes and of the magnetic resonance of fluorine atoms in uranium VI fluorine complexes has made it possible to put forward a structural model for these compounds for which it is impossible, because of the lack of suitable single crystals for X-ray diffraction work, to deduce the exact position of the fluorine atoms. It is shown that it is difficult to interpret the paramagnetism of uranium fluorides, because the uranium ions are in low-symmetry sites. A theoretical study of the magnetism of the U{sup V} ion in complex fluorides of the type M{sub 3}UF{sub 8} (M = NH{sub 4}, Na, Rb, Cs) leads to an interpretation based on a trigonal deformation of the eight fluorine atom structure surrounding the uranium atom. By applying a Hamiltonian spin formalism and making a systematic use of group theory, it is possible to present the susceptibility calculations very concisely. Study of the resonance and of the relaxation of the fluorine atoms in powdered uranium VI complex fluorides suggests a structural model in the case of NaUF{sub 7}. It is shown that the shape of the magnetic resonance absorption lines is strongly affected by the presence of large anisotropic chemical shifts. In the model proposed here, six fluorine atoms are linked to the uranium, atom by strongly covalent bonds in a deformed UF{sub 6} octahedral structure; the seventh fluorine atom remains ionic. The occurrence of a rotational movement of the octahedron is confirmed by a study of the longitudinal relaxation of the fluorine atoms, the activation energy being 0.46 eV. (author) [French] L'etude de la susceptibilite magnetique de complexes fluores d'uranium V et la resonance magnetique des fluors dans des complexes fluores d'uranium VI permettent de proposer un modele structural pour ces composes, ou la diffraction des rayons X, en l'absence de monocristaux convenables, est incapable de preciser la position des atomes de

  6. Beach sediments drift study by means of radioactive tracers; L'etude du transport littoral par la methode des traceurs radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Hours, R. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Jaffry, P. [Electricite de France (EDF), 78 - Chatou (France). Lab. National d' Hydraulique

    1959-07-01

    The present state of the sediments drift studies by means of radioactive tracers is exposed. Various processes of labelling, immersion and detection, used in France and other countries, are reviewed. A more extended analysis of some aspects of the problem by the same authors can be found in 'La Houille Blanche', number 3, may-june 1959 (Rapport C.E.A. number 1269). (author) [French] L'etude du transport littoral des sediments et galets par la methode des traceurs radioactifs est en plein developpement. Le present rapport precise l'etat actuel de la question. Les techniques de marquage, d'immersion et de detection utilisees en France et a l'etranger sont decrites; une analyse plus detaillee de certains aspects de la question est presentee par les memes auteurs dans 'La Houille Blanche', numero 3, mai-juin 1959 (Rapport C.E.A. numero 1269). (auteur)

  7. Hyperfine coupling in gadolinium-praseodymium alloys by specific heat measurements; Etude du couplage hyperfin dans les alliages gadolinium-praseodyme par mesures de chaleur specifique

    Energy Technology Data Exchange (ETDEWEB)

    Michel, J. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-12-01

    We have studied the hyperfine coupling in gadolinium-praseodymium alloys by specific heat measurements down to 0.3 K. In the first part we describe the apparatus used to perform our measurements. The second part is devoted to some theoretical considerations. We have studied in detail the case of praseodymium which is an exception in the rare earth series. The third part shows the results we have obtained. (author) [French] Nous avons etudie le couplage hyperfin d'alliages de gadolinium-praseodyme par des mesures de chaleur specifique jusqu'a 0.3 K. Dans la premiere partie de cette etude nous decrivons le dispositif experimental. La deuxieme partie est consacree a des considerations theoriques. Nous avons etudie en detail le cas du praseodyme qui est une exception dans la serie des terres rares. La troisieme partie est consacree aux resultats experimentaux. (auteur)

  8. Etude d'un systeme de recuperation et de stockage de chaleur pour un systeme eolien-diesel avec stockage d'air comprime

    Science.gov (United States)

    Remillon, Thibaut

    La recherche presentee dans ce memoire porte sur les systemes hybrides eolien-diesel avec stockage d'air comprime (SHEDAC) adaptes a la production d'electricite en sites isoles, et plus precisement sur l'apport d'un systeme de recuperation et de stockage de chaleur (TES) au fonctionnement de ces systemes. Le principe de fonctionnement est le suivant. Quand la puissance eolienne est excedentaire par rapport aux besoins de la charge, le surplus d'energie est utilise pour comprimer de l'air. De ce processus resulte un rechauffement de l'air, on choisit d'extraire et de stocker la chaleur separement. Lors de la phase de restitution d'energie, l'air comprime utilise pour suralimenter le moteur thermique est rechauffe en utili sant la chaleur stockee precedemment. Tout au long de l'etude, nous avons seulement pris en compte la chaleur provenant du processus de compression de l'air, et neglige en tous points du systeme les echanges de chaleur avec le milieu exterieur. Pour quantifier l'apport du systeme de stockage de chaleur, nous avons tout d'abord mene une etude bibliographique sur ces systemes, pour identifier les meilleures solutions disponibles. Ensuite, on a modelise une de ces solutions sous Simulink pour etudier son fonctionnement de maniere plus precise. D'autre part, on a modelise un systeme de stockage de chaleur ideal pour quantifier l'apport maximal d'un TES sur les performances du SHEDAC. Nous avons conclu que les TES les plus adaptes aux systemes SHEDAC etaient les solutions actives directes a deux reservoirs, et que, pour beneficier au maximum du systeme de stockage de chaleur, il etait interessant de realiser la detente de l'air comprime stocke dans un moteur a air comprime, pour maximiser la recuperation d'energie mecanique.

  9. Contribution to the study of deformed heavy nuclei by means of nuclear reactions; Contribution a l'etude des noyaux lourds deformes au moyen de reactions nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Gastebois, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-06-01

    The experimental results obtained in the study of the (d,p) reactions, at E{sub d} = 12 MeV, on the three even-even deformed nuclei {sup 170}Yb, {sup 172}Yb and {sup 174}Yb have been analysed in terms of DWBA calculations. The spectroscopic information relative to the odd final nuclei have been compared with the predictions of the collective model and of the Nilsson's model. The effect of various parameters used in the DWBA analysis (form factors, optical wave functions) has been carefully studied. The observed differences between the three final nuclei are qualitatively reproduced in the experimental study of resonances, seen in excitation functions of elastically and inelastically scattered protons on the same target nuclei, and corresponding to analogue states in the three nuclei {sup 171}Lu, {sup 173}Lu and {sup 175}Lu. (author) [French] Les resultats experimentaux de l'etude des reactions (d.p) a E{sub d} = 12 MeV, sur les noyaux deformes pairs-pairs {sup 170}Yb, {sup 172}Yb et {sup 174}Yb ont ete interpretes dans le cadre de l'approximation de Born des ondes deformees. Les informations spectroscopiques relatives aux noyaux impairs finals ont ete comparees aux predictions du modele collectif et du modele de Nilsson, apres avoir examine avec soin l'influence des differents parametres (facteurs de forme, fonctions d'onde 'optiques') utilises lors de l'analyse. Les differences observees entre les trois noyaux finals sont qualitativement reproduites par les resultats experimentaux de l'etude de resonances dans les fonctions d'excitation de diffusion elastique et inelastique de protons sur les memes noyaux-cibles, lors de la recherche d'etats analogues dans les noyaux {sup 171}Lu, {sup 173}Lu et {sup 175}Lu. (auteur)

  10. Kinetic study of the reaction of nitrogen with uranium monocarbide; Etude cinetique de la reaction de l'azote sur le monocarbure d'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, F.J. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1968-07-01

    The nitridation of uranium monocarbide pieces, microspheres and powder as well, is investigated in the temperature range 700 - 1200 deg. C and the kinetics of this reaction specified, using a thermogravimetric experimental procedure. In every case; the kinetics appears to be linear, except for massive monocarbide at temperatures above 950 deg. C which obeys following the rate law: {delta} m{sup x} = Kt, with x = 1.5 {+-} 0.1 Accordingly, the activation energy varies from 15 to 30 Kcal/mole. Furthermore, as evidenced by the curves K = F(P), the rate of nitridation increases proportionally to the square root of nitrogen pressure. The particular behaviour of the powders can be accounted for through a study of their 'over-temperature'. On the basis of all experimental results, the author suggests a reactional mechanism. (author) [French] L'etude thermogravimetrique de nitruration du monocarbure d'uranium sous differentes formes: massif, billes, poudre, entre 700 et 1200 deg. C, permet de connaitre la cinetique de cette reaction. Dans tous les cas la loi est lineaire sauf pour le monocarbure massif aux temperatures superieures a 950 deg. C, ou elle peut s'exprimer sous la forme: {delta} m{sup x} = Kt avec x = 1,5 {+-} 0,1 L'energie d'activation varie de 15 a 30 Kcal/mole suivant le type de loi rencontre. Les courbes K = F(P) montrent que la vitesse de nitruration croit avec la racine carree de la pression d'azote. L'etude de surtemperature des poudres permet d'expliquer leur comportement particulier. L'auteur propose un mecanisme reactionnel regroupant l'ensemble des resultats experimentaux. (auteur)

  11. Experimental investigation of smectite hydration from the simulation of 001 X-ray diffraction lines. Implications for the characterization of mineralogical modifications of the 'argilite' from the Meuse - Haute Marne site as a result of a thermal perturbation; Etude experimentale de l'hydratation des smectites par simulation des raies OOl de diffraction des rayons X. Implications pour l'etude d'une perturbation thermique sur la mineralogie de l'argilite du site Meuse-Haute Marne

    Energy Technology Data Exchange (ETDEWEB)

    Ferrage, E

    2004-10-15

    The structural modifications affecting the reactive mineral constituents of the clay barriers (smectite) and possibly resulting from the thermal pulse related to nuclear waste storage are essentially limited to the amount and location of the layer charge deficit. These modifications likely impact the hydration properties of these minerals, and a specific methodology has thus been developed to describe, using simulation of X-ray diffraction profiles (001 reflections), these hydration properties and specifically the heterogeneity resulting from the inter-stratification of different layer types, each exhibiting a specific hydration state. The detailed study of the hydration properties of a low-charge montmorillonite (octahedral charge) has shown that the affinity of the interlayer cation for water rules the hydration state and the thickness of hydrated smectite layers. If the layer charge is increased, the transition between the different hydration states is shifted, following a water desorption isotherm, towards lower relative humidities. In addition, the hydration of studied beidellites (tetrahedral charge) was shown to be more heterogeneous than that of montmorillonites. The developed methodology also allowed describing the structural modifications resulting from a chemical perturbation (chlorinated anionic background, pH). Finally, the link between the thickness of elementary layers and the amount of interlayer water molecules has been evidenced. A new structure model has also been determined for these interlayer species allowing an improved description of their positional distribution in bi-hydrated interlayers. (author)

  12. Experimental study and modeling of CH{sub 4}/O{sub 2}/Ar and C{sub 2}H{sub 6}/O{sub 2}/Ar pre-mixing laminar flames; Etude experimentale et modelisation de flammes laminaires de premelange CH{sub 4}/O{sub 2}/Ar et C{sub 2}H{sub 6}/O{sub 2}/Ar

    Energy Technology Data Exchange (ETDEWEB)

    Crunelle, B.; Desgroux, P.; Pauwels, J.F. [Lille-1 Univ., 59 - Villeneuve-d`Ascq (France). Laboratoire de Cinetique et Chimie de la Combustion URA-CNRS

    1996-12-31

    New studies are always needed to better determine the physico-chemical processes involved in the combustion of natural gas. The understanding of the reaction mechanisms that lead to the formation of nitrogen oxides or volatile organic compounds requires to identify the inner mechanisms which take place during combustion and in particular the mechanisms of formation of intermediate products. The aim of this study is to analyze the thermal degradation of methane and ethane in low pressure pre-mixed stabilized laminar flames condition, because both of these compounds represent the major part of natural gas composition. The main chemical reaction ways identified in the studied flames and responsible for combustion have been identified after a comparison between experimental results and the computerized simulation performed using an a-priori postulated chemical mechanism. This study stresses on the transfer reaction schemes between the different C1, C2 and C3 oxidation ways which play an important role in the formation of intermediate hydrocarbons. (J.S.) 13 refs.

  13. Influence of age on radioinduced cognitive disorders: Experimental studies with cerebral irradiation of 30 Gy in 10 sessions and 12 days in the Wistar rat at 1.5, 4 and 18 months; Influence de l'age sur les troubles cognitifs radioinduits : etudes experimentales avec irradiation cerebrale de 30 Gy en 10 seances et 12 jours chez le rat Wistar de 1 1/2, 4 et 18 mois

    Energy Technology Data Exchange (ETDEWEB)

    Lamproglou, I. [Lab. de Chimie et Biophysique des Traceurs, Faculte de Medecine Xavier Bichat, Paris (France); Baillet, F.; Boisserie, G.; Mazeron, J.J. [Service de Radiotherapie, Hopital de la Pitie-Salpetriere, Paris (France); Delattre, J.Y. [Dept. of Neurology and Inst. National de la Sante et de la Recherche Medicale, INSERM, Hopital de la Pitie-Salpetriere, Paris (France)

    2002-07-01

    The objective of this study was to determine the influence of age on the learning and memory dysfunction induced by cranial radiation in the male Wistar rat. Ninety-six 45-day-old, 70 4-month-old, and 78 18-month-old male rats were divided in two equal groups: (i) irradiated and (ii) control. A course of whole-brain radiation therapy (30 Gy in 10 fractions over 12 days) was administered to the irradiated group, while the control group received sham irradiation. Sequential behavioral studies including one and two-way avoidance tests were undertaken before and after the 7 months following radiation. The results suggest that radiation induced progressive and irreversible memory dysfunction in elderly (18-month-old) rats, but this effect was partial or almost reversible in the 4-month-old and 45-day-old rats, respectively. In return, the learning dysfunction was age non-dependent despite the fact that is occurs more rapidly in the young (45 days, 4 months) rats. (author)

  14. Incineration of oxygenated volatile organic compounds. Experimental study and kinetic modeling of the oxidation of methyl ethyl ketone, ethyl acetate and butan-2-ol in methane flames; Incineration de composes organiques volatils oxygenes. Etude experimentale et modelisation cinetique de l'oxydation de la methyl ethyl cetone, de l'acetate d'ethyle et du butan-2-ol dans des flammes de methane

    Energy Technology Data Exchange (ETDEWEB)

    Decottignies, V.

    2000-12-01

    This work deals with the low pressure (0.05 atm) degradation of three volatile organic compounds (VOCs): methyl-ethyl-ketone, ethyl acetate and butan-2-ol, in premixed stoichiometric laminar methane flames seeded with 1 to 3% of each VOC. Molar fraction profiles of species have been obtained using microprobe sampling coupled with a gas chromatography and a mass spectroscopy analysis. Temperature profiles have been obtained using the covered thermocouple technique in the presence of the microprobe. The addition of a VOC in the initial reagents mixture leads to an increase of the quantity of intermediate hydrocarbon compounds and in particular of some soot precursor species. The degradation of VOCs leads to the formation of oxygenated intermediates like methanol, dimethyl-ether, acetaldehyde, propanal, acetone and vinyl acetate, the type of VOC having an effect on the quantities produced. The degradation of a VOC can lead to the formation of more toxic or polluting compounds (methyl vinyl ketone, acetic acid and acrolein) than the VOC itself. In the conditions of the study, the intermediate compounds are totally destructed inside the reactional area of the flame front and are no more present in the burnt gases. Sub-mechanisms of VOC oxidation have been developed using experimental observations and the most recent recommendations of the literature. These sub-mechanisms comprise 49 species involved in 241 elementary reactions. Their validation has been performed by comparing the experiment with the kinetic modeling on the molar fraction profiles of the detected species. Experimental data are well reproduced by the model for most species. The addition of a VOC inside the initial reagents mixture creates an important reactivity increase, in particular in the case of butan-2-ol seeded flames. The analysis of reactional ways has permitted to draw out the main reactions responsible for the degradation of the 3 VOCs and the ways of formation and consumption of the intermediate compounds specific of these VOCs. (J.S.)

  15. Experimental study and modeling of the propagation of an alkaline concentration wave coming from a cement matrix an passing through the argilite of the Meuse / Haute-Marne laboratory; Etude experimentale et modelisation de la propagation d'une onde de concentration alcaline issue d'une matrice cimentiere a travers l'argilite du site du laboratoire Meuse / Haute-Marne

    Energy Technology Data Exchange (ETDEWEB)

    Roussel, Th

    2001-12-01

    The propagation of an alkaline wave through a clay rock has been investigated- The wave is generated by a cementitious matrix through the Callovo-Oxfordian argillite of the Meuse Haute-Marne Laboratory (-480 m depth). The argillite itself is composed of quartz, micas, calcite and an interstratified l/S. In order to characterise the interactions between the alkaline fluid and the argillaceous medium, dynamic column experiments have been carried out. The originality of the investigation methodology consists in exploiting the data generated from the breakthrough curves as well as from the characterisation of the solids extracted from the columns. Two types of processes having totally different reaction times have hence been thoroughly studied: - Fast surface adsorption and condensation reactions: On the one hand cation adsorption reactions by site ionisation have been characterised. They are responsible of the buffering effect of the clays. On the other hand an original reaction of calcium compound condensation in the interlayer space of the swelling clays has been revealed. These processes have been modelled and their simulations with the IMPACT calculation code showed that the models elaborated were very satisfying. - Strongly kinetically limited dissolution/precipitation reactions: The main primary phases dissolved are quartz and interstratified l/S. The precipitation of secondary phases are mainly C(A)SH and zeolites. After the injection of an alkaline fluid for 6 months at 60 deg C, the argillite is strongly amorphized but only 20 to 30% of the quartz and the interstratified I/S are dissolved. Therefore, dissolution kinetics of the primary phases and the solubility products of the main secondary phases have been determined. (author)

  16. CÁNCER Y TERAPÉUTICA CON PRODUCTOS DE LA COLMENA. REVISIÓN SISTEMÁTICA DE LOS ESTUDIOS EXPERIMENTALES Cancer therapy with bee products. Systematic review of experimental studies

    Directory of Open Access Journals (Sweden)

    Andrés Jagua-Gualdrón

    2012-04-01

    Full Text Available Antecedentes. Los productos de la colmena se han utilizados desde hace más de dos milenios con fines terapéuticos. Conceptos teóricos basados en la composición de los productos hacen pensar que podrían ser de utilidad en el manejo del cáncer. Objetivo. Resumir la evidencia experimental disponible en la actualidad sobre el uso de los productos de la colmena en el manejo del cáncer. Material y métodos. Se realizó una revisión sistemática de los estudios experimentales publicados a través de las bibliotecas digitales PUBMED, LiLACS y OVID en los cuales se evaluara la utilidad del uso de los distintos productos de la colmena sobre cultivos de células tumorales o sobre modelos animales de cáncer. Se realizó un análisis cualitativo de la información y se construyeron tablas de resumen. Resultados. La búsqueda arrojó un total de 391 resultados de los cuales únicamente 55 cumplieron los criterios de inclusión. El veneno de abejas, la miel y el propóleo son los productos con un mayor número de publicaciones. La mayoría son estudios in vitro y son pocos los modelos en animales realizado. Se describen los mecanismos de acción a través de los cuales estos podrían llegar a ejercer acciones farmacológicas útiles en el manejo del cáncer. Conclusión. La aplicación de los productos de la colmena en el cáncer es un campo incipiente pero prometedor de investigación. Existe evidencia experimental que documenta la plausibilidad biológica de este uso. Es necesario realizar modelos animales que permitan describir el comportamiento de los productos y documentar su seguridad y utilidad terapéutica en el cáncer.Background. The beehive products have been used for more than two millennia with therapeutic purposes. Theoretical models based on the composition of products suggest that might be useful in cancer management. Objective. To summarize experimental evidence available to date on the use of beehive products in cancer management

  17. Contribution to the study of internal friction in graphites; Contribution a l'etude du frottement interieur des graphites

    Energy Technology Data Exchange (ETDEWEB)

    Merlin, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-03-01

    A study has been made of the internal friction in different graphites between -180 C and +500 C using a torsion pendulum; the graphites had been previously treated thermo-mechanically, by neutron irradiation and subjected to partial annealings. It has been shown that there occurs: a hysteretic type dissipation of energy, connected with interactions between dislocations and other defects in the matrix; a dissipation having a partially hysteretic character which can be interpreted by a Granato-Luke type formalism and which is connected with the presence of an 'ultra-micro porosity'; a dissipation by a relaxation mechanism after a small dose of irradiation; this is attributed to the reorientation of bi-interstitials; a dissipation having the characteristics of a solid state transformation, this during an annealing after irradiation. It is attributed to the reorganization of interstitial defects. Some information has thus been obtained concerning graphites, in particular: their behaviour at low mechanical stresses, the nature of irradiation defects and their behaviour during annealing, the structural changes occurring during graphitization, the relationship between internal friction and macroscopic mechanical properties. (author) [French] L'etude du coefficient de frottement interieur au moyen d'un pendule de torsion entre -180 C et +500 C a ete realisee pour differents graphites apres des traitements thermo-mecaniques, des irradiations neutroniques et des guerisons partielles. Il a ete mis en evidence: une dissipation d'energie a caractere hysteretique, reliee aux interactions des dislocations avec les autres defauts de la matrice; une dissipation a caractere partiellement hysteretique, interpretable par un formalisme type Granato-Lucke et reliee a la presence d'une ''ultra-microporosite''; une dissipation par un mecanisme de relaxation, apres irradiation a faible dose, attribuee a la reorientation de di

  18. Study and achievement of a digital-analog-divider; Etude et realisation d'un diviseur-analogique-numerique

    Energy Technology Data Exchange (ETDEWEB)

    Petin, A. [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1969-04-01

    theorie du systeme, les paragraphes suivants presentent la recherche d'un schema synoptique, l'etude des circuits et la realisation. (auteur)

  19. Reorganizing Geographic Combatant Command Headquarters for Joint Force 2020

    Science.gov (United States)

    2013-05-01

    Claude Bernard, Introduction a l’Etude de la Medecine Experimentale 1 This chapter discusses organizational constructs and relevant terms to establish a...capability, obviously, a nuclear deterrent, although we believe we can do that with a slightly smaller force; certainly maintaining our ability to do

  20. Author Details

    African Journals Online (AJOL)

    Ouagued, A. Vol 17 (2005) - Articles Etude experimentale des capteurs solaires a air: le sechage de la figue. Abstract. ISSN: 1111-0902. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors. OTHER RESOURCES... for Researchers · for Journals · for Authors · for Policy Makers ...

  1. Estadísticos poblacionales de Triatoma sordida Stäl 1859 (Hemiptera : Reduviidae en condiciones experimentales Population statistics of Triatoma sordida Stäl 1859 (Hemiptera: Reduviidae in experimental conditions

    Directory of Open Access Journals (Sweden)

    Elena B. Oscherov

    1996-10-01

    Full Text Available Se realizó el seguimiento longitudinal de cuatro cohortes de 100 huevos cada una. Los insectos fueron criados a 28°C ± 3°C y 63 % ± 10% de humedad relativa, y alimentados cada siete días sobre gallina (Gallus domesticus, durante 40 min. Las cohortes fueron controladas una vez por semana. Se observó un valor constante de supervivencia en las cuatro cohortes, sin picos importantes. La expectativa de vida de los machos, en promedio, fue de 37,4 semanas y la de las hembras 36,8. El tiempo generacional demandó 61,7 semanas. La tasa reproductiva neta indica que esta población se incrementará 143,3 veces con cada generación. La tasa intrínseca de crecimiento natural fue de 0,082 por semana. El máximo valor reproductivo se verificó, en promedio, a la tercer semana del ingreso al estado adulto. La distribución estable de edades de T. sordida sería de 32% huevos, 26% ninfas de primer estadio, 19% ninfas de segundo estadio, 13% ninfas de tercer estadio, 6% ninfas de cuarto estadio, 3% ninfas de quinto estadio y 1% de adultos. Es la primera cita para Argentina sobre la tabla de vida de T. sordida. El análisis de estos parámetros permite considerar que esta especie se comporta como "K estratega", en condiciones experimentales.Foram estudados diferentes parâmetros populacionais de Triatoma sordida em condições de laboratório. Realizou-se um seguimento longitudinal de quatro coortes de 100 ovos cada uma; os insetos foram criados a 28°C ± 3°C e 63% ± 10% de umidade relativa, e alimentados cada sete dias sobre galinha (Gallus domesticus durante 40'. As coortes foram controladas uma vez por semana. A expectativa de vida média dos machos foi de 37,4 semanas e a das fêmeas de 36,8.O tempo médio de desenvolvimento foi de 61,7 semanas. A taxa reprodutiva líquida indica que esta população aumentará 143,2 vezes durante cada geração. A taxa intrínseca do crecimento natural foi de 0,082 por semana. A média do valor máximo reprodutivo

  2. Etude exploratoire des conceptions de la circulation sanguine aupres d'eleves de l'ordre collegial

    Science.gov (United States)

    Robitaille, Jean-Marc

    Il existe peu d'etudes sur les conceptions touchant les domaines de la biologie, notamment sur les conceptions de la circulation sanguine Nous avons observe egalement l'absence de recherche menee aupres d'eleves de l'ordre collegial sur cette question. Nous avons voulu combler une lacune en menant une recherche sur les conceptions de la circulation sanguine aupres d'eleves de l'ordre collegial. Pour mener cette recherche nous nous sommes inspires d'une methode developpee par Treagust (1988). Le premier niveau de formulation didactique etablit l'architecture du systeme et la fonction nutritive de la circulation. Le second niveau de formulation didactique decrit et relie les parametres de la dynamique de la circulation et leur relation: Pression, Debit et Resistance. Le troisieme niveau de formulation didactique s'interesse au controle de la circulation du sang dans un contexte d'homeostasie qui implique la regulation de la pression arterielle. Nous avons construit un questionnaire en nous guidant sur les niveaux de formulation didactique et l'analyse des entrevues menees aupres de dix-huit eleves, representatifs de la population cible. Ce questionnaire fut administre a un echantillon de 2300 eleves disperses dans six colleges de la region de Montreal. Notre echantillon comprend des eleves inscrits a des programmes de l'ordre collegial en Sciences de la nature et en Techniques de la sante et qui n'ont pas suivi le cours sur la circulation sanguine. Notre analyse des reponses des eleves de notre echantillon aux questions sur le premier niveau de formulation didactique revele que la majorite des eleves considerent que le systeme circulatoire relie les organes les uns aux autres dans un circuit en serie. Notre analyse revele egalement que la majorite des eleves estiment que les nutriments sont extraits du sang par les organes selon un processus de selection base sur les besoins determines par la fonction de l'organe. Ces besoins sont differents selon les organes qui ne

  3. Contribution to the study of samarium-151 excited levels; Contribution a l'etude des niveaux excites du samarium-151

    Energy Technology Data Exchange (ETDEWEB)

    Locard, P. [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Grenoble, 38 (France)

    1967-07-01

    The nucleus of {sup 151}Sm, which has 89 neutrons, happens to be on the lower edge of the deformed nuclei of region II. Therefore, the study of its levels is very interesting for the verification of the goodness of the collective models for deformed nuclei when the deformation is small (we introduce these models in the first chapter). {sup 151}Sm has often been studied, but the direct gamma spectrum measured with a lithium drift-germanium detector (chapter 3) shows many high energy transitions which did not appear in the previous level schemes. In order to settle these transitions, we have undertaken gamma-gamma coincidence spectra (as well as sum-coincidence spectra) experiments with a scintillation spectrometer designed in our laboratory (chapter 2). The investigation of the intensities of these coincidences leads us to modify the last proposed level schemes: we suppress the levels at 405,5 and 650 keV, we add levels at 245,6 - 306,6 - 522 - 952 and 962 keV. We have also verified the multipolarities of the main transitions and measured the half-lives of a few levels (chapter 3) (we find a half-life of 1.1 {+-} 0.5 nanosecond for the level at 167,7 keV). In chapter 4, we compare our results to the predictions of the models described in chapter 1. (author) [French] Le noyau de {sup 151}Sm, qui possede 89 neutrons, se trouve a la limite inferieure des noyaux deformes de la region II. L'etude de ses niveaux excites est donc d'un interet tout particulier pour la verification de la validite des differents modeles collectifs pour les noyaux deformes, lorsque la deformation est petite (nous introduisons ces modeles dans un premier chapitre). Le {sup 151}Sm a deja fait l'objet de nombreuses etudes, mais le spectre gamma direct fait avec une jonction de germanium compense au lithium (chapitre 3), nous a montre l'existence d'un grand nombre de transitions de hautes energies qui ne sont pas placees dans les schemas proposes jusqu'a ce jour. Pour

  4. Etude des transformations de phase dans les alliages de titane, 2; contribution à l'étude des transformation de l'alliage de titane TA6 V6 E2 en conditions isothermes après trempe à partir du domaine $(\\alpha + \\beta)$

    CERN Document Server

    Fontalirand, C; Fidelle, J P; Hocheid, B; Beauvais, C no 1; Fidelle, J P no 2; Hocheid, B no 2; Fontalirand, C no 1

    1974-01-01

    Etude des transformations de phase dans les alliages de titane, 2; contribution à l'étude des transformation de l'alliage de titane TA6 V6 E2 en conditions isothermes après trempe à partir du domaine $(\\alpha + \\beta)$

  5. Etude des phenomenes de penetration des especes chimiques dans les revetements cathodiques des cuves d'electrolyse de l'aluminium

    Science.gov (United States)

    Brisson, Pierre-Yves

    Cette these decrit l'etude effectuee sur les phenomenes d'insertion du sodium et de penetration du bain electrolytique dans les revetements cathodiques des cuves d'electrolyse de l'aluminium. L'etude fut effectuee a l'aide d'un montage permettant d'effectuer l'electrolyse en laboratoire. Trois types de revetement cathodiques furent etudies : des blocs semi-graphitique, des blocs graphitiques et des blocs graphitises. L'insertion du sodium dans les trois differents types de blocs fut etudiee a l'aide de la spectrometrie des photoelectrons X (XPS). L'analyse a permis de mettre en evidence deux formes de sodium dans l'anthracite et la phase liante des materiaux semi-graphitiques et graphitiques, indiquant qu'une fraction du sodium se retrouve sous forme adsorbee dans les micropores des materiaux alors que l'autre fraction est inseree dans la structure cristalline du carbone. Dans les phases graphitiques (materiaux graphitises et graphitiques), seuls les micropores sont occupes par le sodium Ce resultat explique la tendance observee selon laquelle l'ajout de graphite dans les blocs permet d'abaisser le gonflement sodique. Les mecanismes de penetration du bain dans le reseau poreux des materiaux furent etudies en microscopie electronique et en diffraction des rayons X sur des echantillons apres differents temps d'electrolyses et en variant l'atmosphere (soit sous argon ou sous azote). Ces analyses ont permis d'identifier le mecanisme conduisant a la mouillabilite du bain sur le carbone en fonction de l'atmosphere entourant l'electrolyse. Ainsi, sous azote, la formation de NaCN dans les pores des materiaux par reactions entre le sodium et l'azote permet une mouillabilite accrue du bain alors qu'en absence d'azote (sous argon), le carbure d'aluminium, formes a la surface des pores, joue un role similaire. Dans ce dernier cas, la penetration du bain est moins rapide etant donnee la necessite de toujours amener des especes contenant de l'aluminium en tete du front de

  6. Contribution to the micrographic study of uranium and its alloys; Contribution a l'etude micrographique de l'uranium et de ses alliages

    Energy Technology Data Exchange (ETDEWEB)

    Monti, H. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1956-06-15

    The present report is the result of research carried out by the radio metallurgy section, to perfect micrographic techniques applicable to the study of samples of irradiated uranium. In the first part of this work, two polishing baths are developed, having the qualities with a minimum of disadvantages inherent in their respective compositions: they are, on the one hand perchloric acid-ethanol mixtures, and on the other hand a phospho-chromic-ethanol bath. In the chapter following, the micrographic attack of uranium is studied. The only satisfactory process is oxidation by cathode bombardment forming epitaxic layers. In the third chapter, an attempt is made to characterise the different surface states of the uranium by dissolution potential measurements and electronic diffraction. In the fourth chapter are given some examples of the application of these techniques to the micrographic study of various uranium alloys. In an appendix, it is shown how the chemical oxidation after phospho-chromic-alcohol polishing allows the different inclusions present in the molten uranium to be distinguished. By X-ray diffraction, uranium monocarbide and mononitride inclusions in particular are characterised. (author) [French] Le present rapport est le resultat de recherches effectuees au service de radiometallurgie pour la mise au point de techniques micrographiques applicables a l'etude d'echantillons d'uranium irradie. Dans la premiere partie de ce travail, nous mettons au point deux bains de polissage qui presentent les qualites inherentes a leur composition respective, avec le minimum d'inconvenients: ce sont d'une part des melanges acide perchlorique-ethanol, et d'autre part un bain phospho-chromique-ethanol. Dans le chapitre suivant, nous etudions l'attaque micrographique de l'uranium. Seul le procede d'oxydation par bombardement cathodique formant des couches epitaxiques, est satisfaisant. Dans le troisieme chapitre, nous essayons

  7. Clinical and symptomatological study of pigs subjected to a lethal dose of integral gamma irradiation; Etude clinique et symptomatologique chez le porc soumis a une irradiation gamma totale a dose letale

    Energy Technology Data Exchange (ETDEWEB)

    Vaiman, M.; Guenet, J.-L.; Maas, J.; Nizza, P

    1966-05-01

    Results are reported from a clinical and haematological study on a Corsican species of pigs wholly exposed to an approximately lethal dose of {gamma} radiation. The aim of this work was to examine the changes in the irradiation syndrome of irradiation for pigs to make it thus possible to devise further experiments, in particular in the therapeutic field. The dose received was 285 rads (measured as the absorption in the vertical antero-posterior medial plane). Data are presented on cyto-haematological changes in the blood circulating immediately after irradiation, and followed up to death, and changes in the medullary cytology after irradiation. The clinical picture of lethal radiation injury in swine is described. (authors) [French] Les auteurs rapportent les resultats d'une etude clinique et hematologique chez des porcs de race corse irradies in toto a dose sensiblement letale. Le but de cette etude etait de connaitre l'evolution du syndrome aigu d'irradiation chez le porc et de permettre ainsi le developpement d'experimentations ulterieures, en particulier dans le domaine therapeutique. La dose delivree etait de 285 rad (en dose absorbee au niveau du plan median vertical anteroposterieur. L'etude a porte essentiellement: 1. Sur les modifications cyclo-hematologiques du sang circulant immediatement apres l'irradiation, pour les differentes lignees cellulaires; l'evolution de ces modifications a ete notee jusqu'a la mort; 2. Sur les modifications de la cytologie medullaire apres irradiation (evolution du myelogramme et essai d'evaluation de la cellularite de la moelle osseuse);: 3. Sur les signes cliniques, d'ailleurs tres discrets, observes chez les porcs apres irradiation. (auteurs)

  8. Study and installation of concrete shielding in the civil engineering of nuclear construction (1960); Etude et mise en place des betons de protection dans le genie civil des ouvrages nucleaires (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, F. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    The object of this report is to give technical information about high density concretes which have become very important for radiation biological shielding. The most generally used heavy aggregates (barytes, ilmenite, ferrophosphorus, limonite, magnetite and iron punching) to make these concretes are investigated from the point of view prospecting and physical and chemical characteristics. At first, a general survey of shielding concretes is made involving the study of components, mixing and placing methods, then, a detailed investigation of some high density concretes: barytes concrete, with incorporation of iron punching or iron shot, ferrophosphorus concrete, ilmenite concrete and magnetite concrete, more particularly with regard to grading and mix proportions and testing process. To put this survey in concrete form, two practical designs are described such as they have been carried out at the Saclay Nuclear Station. Specifications are given for diverse concretes and for making the proton-synchrotron 'Saturne' shielding blocks. (author) [French] Ce rapport a pour objet de donner des precisions techniques au sujet des betons a haute densite qui ont pris une grande importance pour la protection biologique contre les rayonnements. Les agregats lourds les plus couramment utilises (barytine, ilmenite, ferrophosphore, limonite, magnetite et riblons) pour la fabrication de ces betons, sont examines du point de vue prospection et caracteristiques physiques et chimiques. On procede d'abord a une etude generale des betons de protection comprenant l'etude des constituants, de la confection et de la mise en place, ensuite, a un examen detaille de quelques betons a haute densite: betons a base de barytine, avec incorporation de riblons ou de grenaille de fonte, betons au ferrophosphore, a base d'ilmenite ou de magnetite, notamment en ce qui concerne la granulometrie, la composition, le dosage et les processus d'essais. Pour concretiser ces

  9. Electronic temperature measurement on the deca II plasma using the Bremsstrahlung; Mesure de la temperature electronique du plasma de deca II par etude du rayonnement de freinage

    Energy Technology Data Exchange (ETDEWEB)

    Dumas, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-06-01

    The electronic temperature of the DECA II machine's plasma is determined by studying the Bremsstrahlung. Two types of detectors are used for this measurement, a set scintillator-photo-multiplicator and a photoelectric effect detector with a massive silver target. The method used is the classical 'absorbent method', The absorbents used are thin formvar foils whose thickness is between 600 and 12 500 angstrom. The measurements done in two different working conditions of the DECA II machine have given: Te {approx_equal} 200 eV in the first case and Te {approx_equal} 70 eV in the second case. (author) [French] Nous avons determine la temperature electronique du plasma de la machine DECA II par l'etude du rayonnement de freinage. Pour cette mesure nous avons utilise deux types de detecteurs: des ensembles scintillateur-photomultiplicateur et un detecteur a effet photoelectrique a cible massive en argent. La methode utilisee pour cette mesure est la classique methode des absorbants. Nous avons utilise des feuilles de format tres mince (de 600 a 12 500 angstrom) comme absorbant. Les mesures faites dans deux regimes de travail differents de la machine DECA II nous ont conduit a: Te {approx_equal} 200 eV dans un cas et Te {approx_equal} eV dans l'autre cas. (auteur)

  10. Some techniques for studying actomyosin by electron microscopy; Quelques techniques d'etude de l'actomyosine par microscopie electronique

    Energy Technology Data Exchange (ETDEWEB)

    Herzberg, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires. Departement de Biologie

    1967-07-01

    A method has been developed for shadowing using a platinum-carbon alloy; it has been applied to the study of the interaction of actomyosin with its substrate ATP. The results obtained seem to favour the hypothesis of a dissociation of the actomyosin into its two components: actin and myosin. Pictures have been obtained showing particles resembling non-polymerized myosin but no rigorous proof of this exists. (author) [French] Une methode d'ombrage par un alliage de platine et carbone a ete mise au point et appliquee a l'etude de l'interaction de l'actomyosine et de son substrat l'ATP. Les resultats obtenus semblent pencher en faveur de la these d'une dissociation de l'actomyosine en ses deux constituants: l'actine et la myosine. Des images ont ete obtenues montrant des particules dont l'identite avec la myosine non polymerisee reste a demontrer plus rigoureusement. (auteur)

  11. Studies on solid-state physics carried out with the Saclay reactor (1962); Etudes de physique du solide realisees a la pile de Saclay (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Herpin, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    This paper deals only with solid-state physics experiments carried out on outgoing beams: rather than giving a general review of the work performed, if refers to only a few of the most important studies or those nearest completion. These are being made with the experimental beams of the two Saclay reactors EL-2, with a central flux of 10{sup 13} n/cm{sup 2}, and - since 1958 - EL-3, whose central flux is equal ta 10{sup 14} n/cm{sup 2}. The experiments are being carried out by two separate groups of physicists, employing different techniques, namely neutron diffraction using a crystal spectrometer, and inelastic scattering using a time-of-flight spectrometer. (author) [French] Cet expose ne relate que des experiences de physique du solide faites sur des faisceaux sortis; plutot que de donner une revue de l'ensemble des travaux effectues, on ne cite que quelques etudes que l'on peut considerer comme plus essentielles ou mieux achevees. On utilise les faisceaux experimentaux des deux piles de Saclay, EL-2 dont le flux au centre est de 10{sup 13}n/cm{sup 2} et, depuis 1958, EL-3 pour laquelle il est egal a 10{sup 14} n/cm{sup 2}. Les experiences sont realisees par deux groupes de physiciens distincts, employant des techniques differentes, la diffraction des neutrons qui utilise un spectrometre a cristal, et la diffusion inelastique avec un spectrometre a temps de vol. (auteur)

  12. Etudes optiques de nouveaux materiaux laser: Des orthosilicates dopes a l'ytterbium: Le yttrium (lutetium,scandium) pentoxide de silicium

    Science.gov (United States)

    Denoyer, Aurelie

    La decouverte et l'elaboration de nouveaux materiaux laser solides suscitent beaucoup d'interet parmi la communaute scientifique. En particulier les lasers dans la gamme de frequence du micron debouchent sur beaucoup d'applications, en telecommunication, en medecine, dans le domaine militaire, pour la, decoupe des metaux (lasers de puissance), en optique non lineaire (doublage de frequence, bistabilite optique). Le plus couramment utilise actuellement est le Nd:YAG dans cette famille de laser, mais des remplacants plus performants sont toujours recherches. Les lasers a base d'Yb3+ possedent beaucoup d'avantages compares aux lasers Nd3+ du fait de leur structure electronique simple et de leur deterioration moins rapide. Parmi les matrices cristallines pouvant accueillir l'ytterbium, les orthosilicates Yb:Y 2SiO5, Yb:Lu2SiO5 et Yb:Sc2SiO 5 se positionnent tres bien, du fait de leur bonne conductivite thermique et du fort eclatement de leur champ cristallin necessaire a l'elaboration de lasers quasi-3 niveaux. De plus l'etude fine et systematique des proprietes microscopiques de nouveaux materiaux s'avere toujours tres interessante du point de vue de la recherche fondamentale, c'est ainsi que de nouveaux modeles sont concus (par exemple pour le champ cristallin) ou que de nouvelles proprietes inhabituelles sont decouvertes, menant a de nouvelles applications. Ainsi d'autres materiaux dopes a l'ytterbium sont connus pour leurs proprietes de couplage electron-phonon, de couplage magnetique, d'emission cooperative ou encore de bistabilite optique, mais ces proprietes n'ont encore jamais ete mises en evidence dans Yb:Y 2SiO5, Yb:Lu2SiO5 et Yb:Sc2SiO 5. Ainsi, cette these a pour but l'etude des proprietes optiques et des interactions microscopiques dans Yb:Y2SiO 5, Yb:Lu2SiO5 et Yb:Sc2SiO5. Nous utilisons principalement les techniques d'absorption IR et de spectroscopie Raman pour determiner les excitations du champ cristallin et les modes de vibration dans le materiau

  13. Study of immiscibilities in the trilaurylamine - dodecane - nitric acid - plutonium system; Etude des immiscibilites dans le systeme trilaurylamine - dodecane - acide nitrique - plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Saey, J.C. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-07-01

    Phase equilibrium in systems made up of trilaurylamine, dodecane, nitric acid tetravalent plutonium is shown by drawing the triangular diagrams. the study of these diagrams provides informations concerning the causes of immiscibility. Heterogeneity of the organic mixtures can be related to some characteristics of the components- dipole moment, molecular polarizability and hydrogen bond exchanging ability-Depending on these, some rules may be established which can be used to make a proper choice of an additive in order to improve the miscibility. As an application a study on the partial substitution of dodecane with decalin, in plutonium extraction experiments, has been done showing a possible improvement of the extraction process. (author) [French] L equilibre des phases dans les systemes formes a partir de trilaurylamine, de dodecane, d'acide nitrique et de plutonium tetravalent est represente en tracant les diagrammes triangulaires. L'examen de ces diagrammes permet d'apporter certaines precisions en ce qui concerne l'origine des immiscibilites. Celles ci sont ensuite reliees a certaines caracteristiques des constituants: le moment dipolaire, la polarisabilite moleculaire et la tendance a former des liaisons hydrogene. Sur les memes bases, il est possible d'etablir un certain nombre de regles pouvant servir a guider le choix d'un additif ameliorant la miscibilite. En application, une etude sur le remplacement partiel du dodecane par la decaline montre l'interet de l'emploi de ce compose dans le procede de purification du plutonium. (auteur)

  14. Study of some transversal motions of the electron beam of a linac; Etudes des mouvements transversaux du faisceau d'electrons dans un accelerateur lineaire

    Energy Technology Data Exchange (ETDEWEB)

    Bergere, R.; Beil, H.; Veyssiere, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    It is well known that when the magnetic focusing field along the axis of an electron linac increases the output accelerated current does not increase regularly. Such a behaviour is shown to be connected with rotations, in the output plane of the linac, of the center of charges of the beam. These rotations have been displayed experimentally by means of a beam position monitoring system and related to the transverse momentum transferred to the beam by the spurious TM{sub 11} mode existing in the input coupler changing the TE{sub 01} mode from the input rectangular waveguide into a circular TM{sub 01} mode on the accelerator structure. (authors) [French] II est bien connu que lorsque le champ magnetique de focalisation, le long de l'axe d'un accelerateur a electrons, augmente, le courant accelere ne croit pas regulierement a la sortie de l'accelerateur. Une telle propriete est associee a des rotations, dans le plan de sortie de l'accelerateur, du centre de gravite des charges du faisceau. Ces rotations ont ete affichees experimentalement grace a un systeme moniteur de la position du faisceau. Elles sont dues a la quantite de mouvement transversale conferee au faisceau par le mode parasite TM{sub 11} regnant dans le coupleur d'entree qui transforme le mode TE{sub 01} du guide rectangulaire d'amenee de la puissance en un mode TM{sub 01} circulaire sur le guide accelerateur. (auteurs)

  15. Contribution to the study of the electrostatic precipitation of aerosols; Contribution a l'etude de la precipitation electrostatique des aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Madelaine, G. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires; Roure, L. [Societe Bertin et Cie, 89 - Druyes Les Belles Fontaine (France)

    1966-07-01

    The first part is devoted to the theory of the electrostatic precipitation of ions in a cylindrical apparatus. Some aerodynamic factors influencing the quality of the flow are deduced. The second part of the report deals with the experimental verification of the hypotheses concerning the laminarity of the gas flow. The presence of a guard tube which ensures a steady state of velocity and which reduces electrical field end-effects should make it possible to obtain a better knowledge of the distribution function of the captured particles. The third part deals with the treatment of the results and with the processing method making it possible to obtain the spectral distribution of the particles captured on the electrode. (authors) [French] La premiere partie est consacree a la theorie de la precipitation electrostatique des ions dans un capteur cylindrique. Des imperatifs d'ordre aerodynamique caracterisant la qualite de l'ecoulement sont degages. La seconde partie traite de la verification experimentale des hypotheses de laminarite du courant gazeux. La presence d'un tube de garde assurant un profil stationnaire de vitesse et attenuant les effets de bouts du champ electrique, doit permettre de mieux connaitre la fonction de repartition des particules captees. La troisieme partie traite de l'exploitation des resultats et de la methode de depouillement permettant l'obtention de la repartition spectrale des particules captees sur l'electrode. (auteurs)

  16. Datos experimentales de la cinética del secado y del modelo matemático para pulpa de cupuaçu (Theobroma grandiflorum en rodajas Kinetic drying experimental data and mathematical model for cupuaçu pulp (Theobroma grandiflora slices

    Directory of Open Access Journals (Sweden)

    Abraham Damian Giraldo-Zuniga

    2010-03-01

    Full Text Available En este trabajo fueron obtenidos experimentalmente la cinética del secado de la pulpa de cupuaçu en forma de rodajas con espesor de 0,5 cm. El secado fue realizado utilizándose un secador laboratorial de bandejas, a las temperaturas de 50, 60 y 70 ºC y a la velocidad del aire de secado de 1,5 m/s. De acuerdo con los datos de la cinética del secado se puede observar que cuanto mayor es la temperatura del secado mayor es la velocidad del secado. El tiempo requerido para secar el producto hasta una humedad del 20%, fueron 9,2, 8,1 y 7,3 horas para las temperaturas de secado de 50, 60 y 70 ºC respectivamente. Las curvas experimentales del secado fueron ajustados al modelo difusional de Fick considerándose la muestra como una lámina infinita y al modelo de Page. Los dos modelos se ajustaron bien a los datos experimentales. Los coeficientes de difusión del modelo de Fick variaron de 1.171 a 1.561 m/s².This work examined experimentally the kinetics of drying cupuaçu pulp (Theobroma grandiflorum slices. The experimental runs were driven in a laboratory dryer, at temperatures of 50, 60 and 70 ºC and an air drying velocity of 1.5 m/s. According to the kinetics study, increasing the temperature led to a decrease in drying time. The required drying times were 9.2, 8.1 and 7.3 hours for drying temperatures of 50, 60 and 70 ºC respectively. The experimental drying curves were adjusted to Fick's diffusional model for an infinite lamina with shrinkage and Page model. The diffusion coefficients of the Fick model varied between 1.171 and 1.561 m/s².

  17. Syntheses and study of pyrrolidinic nitroxide free radicals. Preparation of a nitroxide-type stable bi-radical; Synthese et etudes de radicaux libres nitroxydes pyrrolidiniques. Preparation d'un biradical stable du type nitroxyde

    Energy Technology Data Exchange (ETDEWEB)

    Dupeyre, R.M. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires, Laboratoire de chimie organique physique

    1967-12-01

    Syntheses and study of pyrrolidinic nitroxide free radicals: These radicals are obtained by oxidation, with hydrogen peroxide, of pyrrolidinic amines prepared from triacetonamine by ring contraction. The U. V,, I. R, and E.P.R. spectral characteristics have been determined. The oxidation of these amines with hydrogen peroxide has led also to rupture of the pentagonal ring; some of the decomposition products have been identified. The high chemical stability of the nitroxide group has made it possible to synthesize and study a stable bi-radical. (author) [French] Syntheses et etudes de radicaux libres nitroxydes pyrrolidiniques: Ces radicaux sont obtenus par oxydation l'eau oxygenee d'amines pyrrolidiniques preparees a partir de la triacetonamine par contraction de cycle. Les caracteristiques spectroscopiques ultra-violettes, infra-rouge et resonance paramagnetique sont determinees. Cependant, 1'oxydation de ces amines a l'eau oxygenee a entraine la coupure du cycle pentagonal et identification de certaines substances de decomposition obtenues. La grande stabilite chimique de groupement nitroxyde a permis la synthese et l'etude d'un biradical stable. (auteur)

  18. Development of an analogue multiplexed regulation for periodic 1. order delayed processes; Etude et realisation d'une regulation analogique multiplexee pour processus aperiodiques du 1. ordre avec retard pur

    Energy Technology Data Exchange (ETDEWEB)

    Amblard, J.C. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-07-15

    The present note deals with the study regulations of the sampled type, for 1. order process with simple delay. In order to obtain a good stability in such regulations, together with acceptable performances, it is interesting to use polynomial type correctors acting directly on the sampled error signals. The active elements of these correctors can be shared by all the channels to be controlled. Furthermore, the determination of the correction parameters results from an optimal study of the system. In the second part is described the construction of a multiplexed regulation for diffusion ovens. (author) [French] La presente note concerne l'etude des regulations de type echantillonne, pour processus du 1. ordre avec retard pur. Pour obtenir une bonne stabilite de telles regulations, ainsi que des performances correcte il est interessant d'utiliser des correcteurs de type polynomial, agissant directement sur les signaux d'erreur echantillonnes. Les elements actifs de ces correcteurs peuvent etre pris communs a toutes les voies a controler. D'autre part, la determination des parametres de correction decoula d'une etude optimale du systeme. Dans une seconde partie on decrit la realisation d'une regulation multiplexee de fours a diffusion. (auteur)

  19. Synthese, etude structurale et electrochimique des materiaux d'electrode positive d'oxydes mixtes lithium cobalt nickel oxide (0 /= 1) pour les batteries rechargeables au lithium

    Science.gov (United States)

    Grincourt, Yves

    Depuis une dizaine d'annees, on observe un interet grandissant pour les batteries rechargeables au lithium de tension superieure a 4 volts. La commercialisation de ces batteries pour l'electronique grand marche tend de plus en plus a supplanter celle des accumulateurs Ni-Cd et Ni-MH, de tension nominate 1,2 V. Ces batteries au lithium font appel a des materiaux d'electrode positive (cathode a la decharge) du type oxydes mixtes de metaux de transition LiMnO 2, LiMn2O4, LiNiO2 ou LiCoO2. Si le compose LiCoO2 est relativement aise a synthetiser, il n'en demeure pas moins que le cobalt reste un metal plus couteux compare au nickel et au manganese. La synthese de LiNiO2, quart a elle, demeure un probleme du point de vue stoechiometrique. Un defaut de lithium (5 a 10% molaire) conduira a des proprietes electrochimiques mediocres de la batterie. Dans cette etude nous nous proposons donc de preparer par voie humide et par voie seche les materiaux d'electrode positive de la famille LiCoyNi1-yO2 aver (0 ≤ y ≤ 1) et d'etudier en detail l'influence du pourcentage de nickel et de cobalt sur les proprietes electrochimiques des oxydes mixtes Li-Ni-Co. Une des caracteristiques est la morphologie plus fine des poudres de materiaux, observes par microscopie electronique a balayage (MEB). Un traitement thermique a plus basse temperature (750°C) que pour LiCoO2 (850°C) ainsi qu'un leger exces de lithium dans la preparation, ont permis d'aboutir a un materiau de stoechiometrie quasi parfaite. Neanmoins, le role de pilfer joue par 2 a 4% de moles de Ni2+ presents sur les sites lithium, permet de conserver intacte la structure hexagonale de la maille entre deux cycles consecutifs. Afin de mieux comprendre l'influence du vieillissement dune demi-pile Li/LiMeO2 (Me = Ni, Co) a temperature ambiante, des etudes electrochimiques et d'impedance spectroscopique ont ete menees en parallele. Le vieillissement de la cellule s'accompagne seulement dune chute de son potentiel due a son auto

  20. Contribution to the study of alpha-alpha interaction; Contribution a l'etude de l'interaction alpha - alpha

    Energy Technology Data Exchange (ETDEWEB)

    Darriulai, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-03-01

    Two sets of measurements of the {alpha}-{alpha} elastic scattering differential cross section are presented. The first set - angular distributions from 50 up to 120 MeV - shows two new resonances, 6{sup +} and 8{sup +}, at 25 and 57 MeV. Complex phase shifts are extracted from the data and a phenomenological potential is given. A description of the 3 {alpha}-particle 0{sup +} states in C{sup 12} is made with this interaction potential. The second set - excitation curves between 20 and 50 MeV - allows investigation of the Be{sup 8} level structure within this energy range - It identifies the 16.6 and 16.9 MeV states as 2{sup +}, but the rise of inelastic processes at higher energies makes further identification of spins and parities more and more difficult. (author) [French] Deux series de mesures de la section efficace differentielle de diffusion {alpha}-{alpha} sont presentees. La premiere - distributions angulaires entre 50 et 120 MeV - fait apparaitre deux nouvelles resonances, 6{sup +} et 8{sup +}, a 25 et 57 MeV d'excitation. Des dephasages complexes en sont extraits et un potentiel phenomenologique est presente. Une etude des etats 0{sup +} a parentage (3{alpha}) de {sup 12}C est faite a partir de ce potentiel. La seconde - courbes d'excitation s'etendant de 20 a 50 MeV - met en evidence la structure de {sup 8}Be dans cette region. Elle montre que les niveaux a 16,6 et 16,9 MeV sont des 2{sup +} mais l'importance des processus inelastiques rend difficile l'identification des niveaux d'excitation plus elevee. (auteur)

  1. Observation of allotropic transformations of plutonium with a hot stage microscope; Etude des transformations allotropiques du plutonium au microscopic a platine chauffante

    Energy Technology Data Exchange (ETDEWEB)

    Mars, J.; Spftiet, B. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1965-07-01

    A hot stage microscope designed for the examination of plutonium and its alloys is described. This apparatus was used to study the {alpha} {r_reversible} {beta} and {delta} {r_reversible} {epsilon} allotropic transformations of pure or {beta} and {delta} stabilised plutonium. The {alpha} {yields} {beta} transformation is typically a nucleation and growth process. Some particularities caused by the internal stresses due to the volume change during this transformation are examined. The kinetics has been studied as a function of these stresses and a temperature dependent activation energy for nucleation has been deduced. The {beta} {yields} {alpha} transformation presents a memory effect which implies an orientation relationship between the two phases. This fact is probably caused by the stresses created during the {beta} {yields} {alpha} transition. The {beta} {r_reversible} {gamma} and {delta} {r_reversible} {epsilon} transformations are also diffusion governed processes. (authors) [French] On decrit un microscope a platine chauffante permettant l'examen du plutonium et de ses alliages. Cet appareil a servi a l'etude des transformations {alpha} {r_reversible} {gamma} et {delta} {r_reversible} {epsilon} du plutonium pur ou stabilise en phase {beta} et {delta}. La transformation {alpha} {yields} {beta} est une transformation typique par germination et croissance; elle presente des caracteristiques bien particulieres qui sont dues aux contraintes internes qui prennent naissance au changement de volume a la transformation; la cinetique a ete etudiee en fonction de ces contraintes, et on en a deduit une energie d'activation pour la germination variable avec la temperature. La transformation {beta} {yields} {alpha} presente un effet de memoire qui suppose une relation d'orientation entre les deux phases; ce phenomene semble lie comme auparavant aux contraintes creees par le passage {beta} {yields} {alpha}. Les transformations {beta} {r

  2. Le transfert de connaissances entre les mathematiques et les sciences. Une etude exploratoire aupres d'eleves de 4e secondaire

    Science.gov (United States)

    Samson, Ghislain

    2003-06-01

    Au moment ou dans plusieurs pays on travaille a refondre les programmes d'etudes, tant au primaire qu'au secondaire, l'interet pour le transfert renait. Un des concepts fondamentaux en apprentissage consiste en l'habilete a reutiliser de facon consciente et efficace un acquis d'une situation a une autre situation. Cette recherche emane de preoccupations professionnelles au moment ou le chercheur etait enseignant au secondaire. Au cours de ces annees, il lui a ete possible de constater que plusieurs eleves percevaient difficilement les liens presents entre les disciplines mathematiques et scientifiques. Des travaux en psychologie cognitive et plus particulierement selon une perspective du traitement de l'information ont servi de cadre de reference pour evaluer et analyser les capacites de transfert aupres d'eleves de 4e secondaire. Ce cadre de reference permet de formuler le principal objectif qui est de mieux comprendre le processus de transfert chez des eleves en situation de resolution de problemes scientifiques. Cette these s'interesse donc au transfert en tant que phenomene important du processus d'apprentissage au sens de l'integration. La methode de recherche choisie, de nature qualitative, est principalement axee sur l'evaluation de la capacite a transferer des connaissances lors d'une epreuve et d'un entretien. Pour evaluer ce potentiel de transfert, nous avons elabore deux outils: une epreuve en mathematiques et en sciences et un guide d'entretien. Pour la passation de l'epreuve, le chercheur a pu compter sur la collaboration de 130 sujets provenant de deux ecoles. L'entretien complete la prise de donnees avec 13 sujets ayant accepte de poursuivre l'etude. Les donnees recueillies par ces instruments font ensuite l'objet d'une analyse de contenu. En premier lieu, les verbatims de l'epreuve et de l'entretien ont ete transcrits, puis codifies. La correction des reponses fournies pour les problemes resolus s'est faite a partir d'une grille d

  3. Blowing loop in the EL-4 reactor: CO{sub 2} flow control analogue study; Boucle de soufflage de la centrale EL-4 - regulation du debit CO{sub 2} - etude analogique

    Energy Technology Data Exchange (ETDEWEB)

    Chazal, G.; Merle, J.P.; Guillemard, B. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Leroy, C.; Robin, L.; Jacquin, J.C.; Cornudet, A. [Societe INDATOM, France (France)

    1966-07-01

    This report describes one study which contributed to the construction of the Monts d'Arree nuclear power station: EL-4. The reactor is cooled by a CO{sub 2} current provided by 3 turbo-blower groups. The priming vapour for the turbines is taken at the exit of the main CO{sub 2} - H{sub 2}O exchangers. The operation of EL 4 is based on a high degree of centralization of the controls which attributes an important role to the general regulation circuits. This general regulation includes in particular an internal blowing loop which controls the CO{sub 2} flow. The study of the control of this CO{sub 2} flow is made up of 3 parts: - analogue representation of the reactors cooling circuit and of the turbo blower unit. - first test campaign using the analogue computer describing the natural behaviour of the system in the absence of control. theoretical determination of the regulation factors; definition of the regulation using an analogue computer and second test campaign for recording the performances of the blowing loop. The 4. part of the report deals with the analogue study: analogue equations - development. (authors) [French] Ce rapport prend place parmi les etudes de realisation de la Centrale des Monts d'Arree EL-4. Le reacteur est refroidi par une circulation de CO{sub 2} assuree par 3 groupes turbosoufflantes. La vapeur d'entrainement des turbines est prelevee a la sortie des echangeurs principaux CO{sub 2} - H{sub 2}O. L'exploitation de EL-4 repose sur une centralisation poussee des moyens de controle-commande qui attribue un role essentiel aux circuits de regulation generale. Cette regulation generale comporte en particulier une boucle interne de soufflage qui realise un asservissement du debit de CO{sub 2}. L'etude de cette regulation du debit CO{sub 2} comprend 3 parties: - representation analogique du circuit de refroidissement du reacteur et de l'ensemble turbine-soufflante. - premiere campagne d'essais sur calculateur

  4. Study of gamma radiation between 0.1 and 1.0 MeV in the earth's atmosphere; Etude du rayonnement gamma entre 0,1 et 1 Mev dans l'atmosphere terrestre

    Energy Technology Data Exchange (ETDEWEB)

    Boclet, D. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-01-01

    The present work is devoted to some of the particular problems arising in the detection and localisation of sources of gamma radiation situated outside the earth's atmosphere. These weak sources can only be detected and localized if care is taken to eliminate gamma and particle radiations coming from other sources in the earth's atmosphere and in space. In order to separate the various sources of background noise, generally much stronger than the radiation under study, use is made of a directional detector whose characteristics are determined as described in the first part of the following report. The closest diffuse source considered is that constituted by the earth's atmosphere. Its detailed study will make it possible both to eliminate its effect when sources outside the earth are to be measured, and to predict the amount of secondary gamma radiation emitted by the same process in other celestial bodies, the moon in particular. This work considered in the 2. and 3. parts of the report. (author) [French] La presente etude est consacree a certains des problemes particuliers poses par la detection et la localisation des sources de rayonnement gamma situees hors de l'atmosphere terrestre. Ces sources faibles ne peuvent etre detectees et localisees que si l'on se protege des rayonnements gamma et particulaires provenant d'autres sources situees dans l'atmosphere terrestre et dans l'espace. Pour separer ces divers composants parasites, en general beaucoup plus intenses que le rayonnement a etudier, nous emploierons un detecteur directif dont nous determinons les caracteristiques dans la premiere partie de l'expose qui suit. La source diffuse la plus proche que nous considerons comme parasite est constituee par l'atmosphere terrestre. Son etude detaillee nous permettra d'une part de nous en proteger lorsque nous voudrons etudier les sources {gamma} extra-terrestres, d'autre part de prevoir le rayonnement gamma

  5. Caracterización del borde de un relicto de bosque altoandino dominado por Chusquea scandens (Kunth y evaluación del efecto de disturbios experimentales sobre la regeneración natural en la Reserva forestal municipal de Cogua (Cundinamarca, Colombia

    Directory of Open Access Journals (Sweden)

    Vargas Ríos Orlando

    2004-12-01

    Full Text Available El presente estudio se realizó en la Reserva Forestal Municipal de Cogua (Cundinamarca, Colombia, como parte del proyecto “Hacia un modelo de restauración del bosque”. Tiene como objetivos caracterizar el borde de avance del bosque, dominado por la especie Chusquea scandens y evaluar la regeneración de especies luego de disturbios experimentales a lo largo del borde de bosque. Con el primero se generó información preliminar del estado del borde de avance y del potencial que puede existir allí para la regeneración natural de la vegetación, el muestreo se realizó entre los meses de julio y octubre de 2003, en el cual se evaluaron algunas condiciones bióticas, abióticas y edáficas por medio del método línea intercepto a lo largo del gradiente pastizal-chuscal-bosque. El segundo estableció que tipo de disturbios son favorables para activar y potencializar la regeneración en los bordes de avance dominados por el chusque, los disturbios se basaron en reducir la competencia que hace el chusque por luz, así como también aumentar la disponibilidad de espacio para el establecimiento de otras especies. Para la caracterización del borde de avance se obtuvo que hacia el pastizal el chusque presenta una
    alta densidad que genera una zona de difícil acceso, lo cual puede funcionar como una barrera natural que reduce la influencia de especies de áreas abiertas en el interior del borde de avance, en donde se presentan peque��os claros donde el chuscal se reduce y se muestra una regeneración natural de especies. Además se estableció que a altas densidades del chusque se reducen las posibilidades de regeneración natural y la implantación de especies arbóreas, así como también, que la regeneración presentada hacia el interior del borde de avance está dominada por especies de borde y de bosque, siendo las herbáceas, enredaderas y arbustos las formas de crecimiento más importantes. Luego de los disturbios experimentales se

  6. Contribution to the study of plasmatic fibrinogen and serum albumin: effects of irradiation; Contribution a l'etude du fibrinogene et de la serum-albumine plasmatiques - effets de l'irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Suscillon, M. [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Grenoble, 38 (France)

    1967-07-01

    The author studies the modifications of properties and structure of serum albumin and fibrinogen solution when subjected to radiation of low energy (X rays). On the other hand, two original techniques are exposed: 1. Amperometric determination of fibrin stabilizing factor or factor XIII of hemostasis. 2. Spectrophotometric study of fibrin formation kinetics. Then showing off and quantitative determination of platelets fibrinogen is exposed. (author) [French] L'auteur etudie les modifications des proprietes et de la structure des molecules de serum-albumine et de fibrinogene en solution soumise a un flux de RX de basse energie. D'autre part deux techniques originales sont exposees : 1. Dosage amperometrique du facteur stabilisant de la fibrine. 2. Etude spectrophotometrique de la cinetique de la fibro-formation. Enfin une mise en evidence et un dosage du fibrinogene plaquettaire sont presentes. (auteur)

  7. Chromosomes and irradiation: in vitro study of the action of X-rays on human lymphocytes; Chromosomes et radiations: etude in vitro de l'action des rayons X sur les lymphocytes humains

    Energy Technology Data Exchange (ETDEWEB)

    Mouriquand, C.; Patet, J.; Gilly, C.; Wolff, C

    1966-07-01

    Radioinduced chromosomal aberrations were studied in vitro on leukocytes of human peripheral blood after x irradiation at 25, 50, 100, 200, and 300 R. The numeric and structural anomalies were examined on 600 karyotypes. The relationship between these disorders and the dose delivered to the blood are discussed. An explanation on their mechanism of formation is tentatively given. (authors) [French] L'etude in vitro des anomalies chromosomiques radioinduites a ete pratiquee sur des leucocytes de sang peripherique preleve chez 4 sujets et irradie aux doses de 25, 50, 100, 200, 300 R. Les aberrations numeriques et structurales ont ete examinees sur 600 caryotypes. Les rapports entre ces anomalies et les doses appliquees sont etudies. Une hypothese sur leur mecanisme de formation est avancee. (auteurs)

  8. X-spectrographic method for plutonium detection. Application to contamination measurements in humans; Etude d'une methode de detection du plutonium par spectrographie X. Application a la mesure des contaminations sur l'homme

    Energy Technology Data Exchange (ETDEWEB)

    Michel Trouble [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    After reviewing the radio-toxicology of plutonium 239 and conventional detection methods using its {alpha}-radiation, the author considers the measurement of the X emission spectrum of plutonium 239 using a proportional counter filled with argon under pressure. This preliminary work leads to the third part of this research involving the detailed study of the possibilities of applying thin alkali halide crystal scintillators to the detection of soft plutonium X-rays; there follows a systematic study of all the parameters liable to render the detection as sensitive as possible: movement due to the photomultiplier itself and its accessory electronic equipment, nature and size of the crystal scintillator as well as its mode of preparation, shielding against external parasitic radiation. Examples of some applications to the measurement of contamination in humans give an idea of the sensitivity of this method. (author) [French] Apres un apercu de la radiotoxicologie du plutonium 239 et des methodes classiques de detection par son rayonnement {alpha}, on etudie le spectre d'emission X du plutonium 239 avec un compteur proportionnel rempli avec de l'argon sous pression. Ce travail preliminaire permet d'aborder la troisieme partie de cette etude dans laquelle nous examinons d'une fagon approfondie les possibilites d'application des cristaux scintillateurs minces d'halogenure alcalin a la detection du rayonnement X mou du plutonium; suit une etude systematique de tous les parametres susceptibles de rendre la detection aussi sensible que possible: mouvement propre du photomultiplicateur et de l'electronique associee, nature et dimensions du cristal scintillateur ainsi que son mode de fabrication, blindage contre les rayonnements parasites exterieurs. Quelques applications a la mesure des contaminations sur l'homme permettent d'apprecier la sensibilite de cette methode. (auteur)

  9. Data processing in gamma spectrometry. Application to the decay schemes study; Traitement des informations en spectrometrie gamma application a l'etude de schemas de desintegration

    Energy Technology Data Exchange (ETDEWEB)

    Boulanger, J.P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires, departement d' electronique generale, service d' instrumentation nucleaire

    1968-06-01

    The purpose of this thesis is the processing of the data issued from a gamma spectrometer, and its applications to the decay schemes study. The mathematical analysis of the full energy peaks, in connection with the very good resolution of semi-conductor detectors, leads to a very accurate determination of the energies. The resolution of complex spectra by the least squares method, completed by a spectra generating process, allows the calculation of branching ratios. Then, the handling of the two dimensional experiments permits the coincidence exam. For each of these methods, the calculation principle, then the systematics tests realized in order to prove their validity and to determine their application ranges as well as some experimental results appropriate to illustrate their possibilities, are presented. The energies of some nuclides, frequently used as standards have been thus measured and the decay schemes of {sup 134}Cs and {sup 110m}Ag determined precisely. (author) [French] Cette these est consacree aux methodes de traitement des informations issues d'un spectrometre {gamma}, et a leur application a l'etude des schemas de desintegration: l'analyse mathematique des pics d'absorption totale, conjuguee avec l'excellent pouvoir de resolution des detecteurs semi-conducteurs, conduit a une determination tres precise des energies. La decomposition des spectres complexes par la methode des moindres carres, completee par un procede de generation de spectres, autorise le calcul des rapports de branchement. Enfin le depouillement des experiences biparametriques permet l'examen des coincidences. Pour chacune de ces methodes, on expose le principe des calculs et les essais systematiques effectues afin d'eprouver leur validite et de definir leurs domaines d'application, ainsi que quelques resultats experimentaux propres a illustrer leurs possibilites. Les energies de quelques isotopes utilises couramment comme etalons ont ainsi ete

  10. Etude de la performance des radars hautes-frequences CODAR et WERA pour la mesure des courants marins en presence partielle de glace de mer

    Science.gov (United States)

    Kamli, Emna

    Les radars hautes-frequences (RHF) mesurent les courants marins de surface avec une portee pouvant atteindre 200 kilometres et une resolution de l'ordre du kilometre. Cette etude a pour but de caracteriser la performance des RHF, en terme de couverture spatiale, pour la mesure des courants de surface en presence partielle de glace de mer. Pour ce faire, les mesures des courants de deux radars de type CODAR sur la rive sud de l'estuaire maritime du Saint-Laurent, et d'un radar de type WERA sur la rive nord, prises pendant l'hiver 2013, ont ete utilisees. Dans un premier temps, l'aire moyenne journaliere de la zone ou les courants sont mesures par chaque radar a ete comparee a l'energie des vagues de Bragg calculee a partir des donnees brutes d'acceleration fournies par une bouee mouillee dans la zone couverte par les radars. La couverture des CODARs est dependante de la densite d'energie de Bragg, alors que la couverture du WERA y est pratiquement insensible. Un modele de fetch appele GENER a ete force par la vitesse du vent predite par le modele GEM d'Environnement Canada pour estimer la hauteur significative ainsi que la periode modale des vagues. A partir de ces parametres, la densite d'energie des vagues de Bragg a ete evaluee pendant l'hiver a l'aide du spectre theorique de Bretschneider. Ces resultats permettent d'etablir la couverture normale de chaque radar en absence de glace de mer. La concentration de glace de mer, predite par le systeme canadien operationnel de prevision glace-ocean, a ete moyennee sur les differents fetchs du vent selon la direction moyenne journaliere des vagues predites par GENER. Dans un deuxieme temps, la relation entre le ratio des couvertures journalieres obtenues pendant l'hiver 2013 et des couvertures normales de chaque radar d'une part, et la concentration moyenne journaliere de glace de mer d'autre part, a ete etablie. Le ratio des couvertures decroit avec l'augmentation de la concentration de glace de mer pour les deux types

  11. Study of alkaline-earth element complexes in anhydrous acetic acid; Etude de complexes des elements alcalino-terreux dans l'acide acetique anhydre

    Energy Technology Data Exchange (ETDEWEB)

    Petit, N. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Institut National des Sciences et Technique Nucleaires, Saclay (France)

    1968-10-01

    We have studied the complexes of alkaline-earth elements in anhydrous acetic acid. Using glass-electrode potentiometry we have studied the titration of alkaline earth acetates with perchloric acid which is the strongest acid in anhydrous acetic acid. These titrations have shown that the basic strength of these acetates increases as follows: Mg < Ca < Si < Ba. The interpretation of the titration curves has made it possible to determine a certain number of reaction constants. A study has also been made of the dissociation, of alkaline earth perchlorates formed during these titrations, since the determination of the reaction constants involves their dissociation constants. During this work it has been possible to show that barium has a particular behaviour, giving a mixed compound (a lower acetate complex) not only in the presence of perchloric acid but also in the presence of sulfuric and hydrochloric acids. These are respectively: the mixed acetate-perchlorate complex of barium: Ba(OAc) (ClO{sub 4}); the mixed acetate-acid sulfate complex of barium: Ba (OAc)(HSO{sub 4}); the mixed acetate-chloride of barium: Ba (OAc)(Cl). (author) [French] Nous nous sommes interesses a l'etude de complexes des elements alcalino-terreux dans l'acide acetique anhydre. Par potentiometrie avec une electrode de verre, nous avons etudie les titrages des acetates alcalino-terreux par l'acide perchlorique, qui est l'acide le plus fort dans l'acide acetique anhydre. Ces titrages ont montre que la force basique de ces acetates croit selon: Mg < Ca < Sr < Ba. L'interpretation des courbes de titrages a permis la determination d'un certain nombre de constantes de reactions. D'autre part, nous avons etudie la dissociation des perchlorates alcalino-terreux formes au cours de ces titrages car leurs constantes de dissociation interviennent dans la determination des constantes de reactions. Au cours de ce travail, nous avons pu mettre en evidence le

  12. Contribution to the study of light nuclei with polarized deuterons; Contribution a l'etude des noyaux legers au moyen de deutons polarises

    Energy Technology Data Exchange (ETDEWEB)

    Arvieux, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-04-15

    We describe roughly the vector and tensor-polarized deuteron source associated with the Saclay fixed energy (22 MeV) cyclotron. This has been used to measure the deuteron asymmetry in d-{alpha} scattering (between 17.7 and 21.4 MeV) and in d-p scattering at 21.7 MeV. Then we develop the formalism of irreducible tensor operators used to describe the polarization of a particle of given spin and we study the helicity formalism used to describe the scattering amplitudes for scattering of deuterons by {alpha} (spin 0) and protons (spin 1/2). We apply the preceding results to the phase shift analysis of scattering cross-sections and: 1) deuteron polarization in d-{alpha} scattering from 10 to 27 MeV from which we obtain indications about the excited states of {sup 6}Li; 2) proton and deuteron polarizations in p-d (or d-p) scattering from 1.5 to 12 MeV so as to get the splitting (due to spin interactions) of P and D waves. (author) [French] On decrit sommairement la source de deutons polarises vectoriellement et tensoriellement associee au cyclotron a energie fixe de Saclay avec laquelle on a mesure l'asymetrie des deutons dans la diffusion d-{alpha} de 17,7 a 21,4 MeV et d-p a 21,7 MeV. Puis or developpe le formalisme des operateurs tensoriels irreductibles utilise pour decrire la polarisation d'une particule de spin quelconque. On etudie ensuite le formalisme de l'helicite dans lequel on etudie la diffusion elastique des deutons diffuses par des particules {alpha} (spin 0) et des protons (spin 1/2). On applique les resultats precedents a l'analyse en dephasages de la section efficace et des polarisations: 1 )des deutons dont la diffusion d-{alpha} de 10 a 27 MeV destinee a donner des indications sur les niveaux excites de {sup 6}Li; 2) des protons et des deutons dans la diffusion p-d de 1,5 a 12 MeV en vue de l'etude de la separation suivant les differentes valeurs du moment total J, des ondes P et D (separation due aux interactions de spin

  13. Gestion des ressources hydriques adaptee aux changements climatiques pour la production optimale d'hydroelectricite. Etude de cas: Bassin versant de la riviere Manicouagan

    Science.gov (United States)

    Haguma, Didier

    Il est dorenavant etabli que les changements climatiques auront des repercussions sur les ressources en eau. La situation est preoccupante pour le secteur de production d'energie hydroelectrique, car l'eau constitue le moteur pour generer cette forme d'energie. Il sera important d'adapter les regles de gestion et/ou les installations des systemes hydriques, afin de minimiser les impacts negatifs et/ou pour capitaliser sur les retombees positives que les changements climatiques pourront apporter. Les travaux de la presente recherche s'interessent au developpement d'une methode de gestion des systemes hydriques qui tient compte des projections climatiques pour mieux anticiper les impacts de l'evolution du climat sur la production d'hydroelectricite et d'etablir des strategies d'adaptation aux changements climatiques. Le domaine d'etude est le bassin versant de la riviere Manicouagan situe dans la partie centrale du Quebec. Une nouvelle approche d'optimisation des ressources hydriques dans le contexte des changements climatiques est proposee. L'approche traite le probleme de la saisonnalite et de la non-stationnarite du climat d'une maniere explicite pour representer l'incertitude rattachee a un ensemble des projections climatiques. Cette approche permet d'integrer les projections climatiques dans le probleme d'optimisation des ressources en eau pour une gestion a long terme des systemes hydriques et de developper des strategies d'adaptation de ces systemes aux changements climatiques. Les resultats montrent que les impacts des changements climatiques sur le regime hydrologique du bassin de la riviere Manicouagan seraient le devancement et l'attenuation de la crue printaniere et l'augmentation du volume annuel d'apports. L'adaptation des regles de gestion du systeme hydrique engendrerait une hausse de la production hydroelectrique. Neanmoins, une perte de la performance des installations existantes du systeme hydrique serait observee a cause de l'augmentation des

  14. Study of various processes for marking sediments with gold-198; Etude de divers procedes de marquages de sediments par l'or 198

    Energy Technology Data Exchange (ETDEWEB)

    Jeanneau, B. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-12-15

    The use of radioactive isotopes for the study of sediment deposits is based mainly on two methods: marking in the mass - a glass of an element which can be activated replaces the sediment; surface marking - a physico-chemical process is used to deposit a radio-element at the surface of the sediment. The second process is used in particular for sands when it is advantageous to have a large number of particles for statistical analysis. The aim of this work was to develop a rapid and simple method of marking which could be applied on the actual site of the experiment where equipment, may be limited. The method recommended for marking sand with gold-198 is a combination of the Petersen (treatment with tin chloride) and Campbell (treatment with silver) methods combined with prior treatments with nitric acid and caustic soda. Using this method it is possible to deposit 125 mg of gold per kilo of sediment with a yield of 95 per cent (i.e. 10 Ci/kg) using a hydrochloric acid solution containing gold. The problem of the solidity of the deposits, of their value and of their reproducibility is discussed from the point of view of the mineral constitution of the sand. (author) [French] L'utilisation d'isotopes radioactifs pour l'etude des deplacements sedimentaires fait, principalement appel a deux methodes: le marquage massique - un verre contenant un element activable remplace le sediment; le marquage superficiel - un traitement physico-chimique permet de deposer un radioelement a la surface du sediment. Le second procede est surtout employe pour les sables lorsqu'il est utile de disposer d'un grand nombre de grains pour des raisons statistiques. Le but de ce travail etait de mettre au point une methode simple et rapide de marquage pouvant etre appliquee sur le site meme de l'experience pour les utilisateurs disposant d'un equipement limite. Le procede preconise pour le marquage des sables par l'or 198 est une combinaison des methodes

  15. Les activités de conservation des lémuriens par le Groupe d’Etude et de Recherche sur les Primates de Madagascar (GERP Conservation activities of lemurs by the Madagascar Primate Research Group (GERP- Groupe d’Etude et de Recherche sur les Primates de Madagascar

    Directory of Open Access Journals (Sweden)

    Rose Marie Randrianarison

    2011-10-01

    Full Text Available Le Groupe d’Etude et de Recherche sur les Primates de Madagascar, une association de conservation, a été créée en 1994 grâce à l’initiative des Enseignants Chercheurs et étudiants du Département de Paléontologie et d’Anthropologie Biologique et du Département de Biologie Animale de l’Université d’Antananarivo. Le GERP regroupe actuellement des membres scientifiques multidisciplinaires Malgaches et étrangers dont la majorité d’entre eux est constituée par des primatologues. Les principales actions du GERP se focalisent sur les travaux de recherche sur les Primates Prosimiens de Madagascar, l’établissement de leur plan de conservation, la découverte de nouvelles espèces de lémuriens, la translocation et le transfert des lémuriens vivant dans des milieux défrichés ou précaires, le suivi et l’abondance des lémuriens ainsi que la révision de leurs aires de distribution. Les résultats des recherches effectuées sur la conservation ont permis de publier des articles dans des revues de renommée nationale et internationale sur la Primatologie. En outre, le renforcement de capacité et l’éducation de la communauté de base, des systèmes éducatifs primaires et supérieurs sur la conservation des lémuriens et l’appui aux activités de développement durable de la population locale s’avèrent nécessaires pour que la conservation des lémuriens soit pérenne.The Madagascar Primate Research Group (GERP - Groupe d’Etude et de Recherche sur les Primates de Madagascar is a conservation-focused association created in 1994 by the initiative of researcher lecturers and students from the Department of Paleontology and Biological Anthropology and the Department of Animal Biology of the University of Antananarivo. The GERP membership consists of multidisciplinary scientists, both Malagasy and foreign, the majority of whom are primatologists. The principle actions of the association are focused on research on the

  16. Etude du processus de changement vecu par des familles ayant decide d'adopter volontairement des comportements d'attenuation des changements climatiques

    Science.gov (United States)

    Leger, Michel T.

    recension des ecrits sur le changement de comportement en environnement. Nous explorons egalement la famille comme systeme fonctionnel de sorte a mieux comprendre ce contexte d'action environnementale qui est, a notre connaissance, peu etudie. Dans le deuxieme article, nous presentons nos resultats de recherche concernant les facteurs d'influence observes ainsi que les competences manifestees au cours du processus d'adoption de nouveaux comportements environnementaux dans trois familles. Enfin, le troisieme article presente les resultats du cas d'une quatrieme famille ou les membres vivent depuis longtemps des modes de vie ecologique. Dans le cadre d'une demarche d'analyse par theorisation ancree, l'etude de ce cas modele nous a permis d'approfondir les categories conceptuelles identifiees dans le deuxieme article de sorte a produire une modelisation de l'integration de comportements environnementaux dans le contexte de la famille. Les conclusions degagees grace a la recension des ecrits nous ont permis d'identifier les elements qui pourraient influencer l'adoption de comportements environnementaux dans des familles. La recension a aussi permis une meilleure comprehension des divers facteurs qui peuvent affecter l'adoption de comportements environnementaux et, enfin, elle a permis de mieux cerner le phenomene de changement de comportement dans le contexte de la famille consideree comme un systeme. En appliquant un processus d'analyse inductif, a partir de nos donnees qualitatives, les resultats de notre etude multi-cas nous ont indique que deux construits conceptuels semblent influencer l'adoption de comportements environnementaux en famille : 1) les valeurs biospheriques communes au sein de la famille et 2) les competences collectivement mises a profit collectivement durant l'essai de nouveaux comportements environnementaux. Notre modelisation du processus de changement dans des familles indique aussi qu'une dynamique familiale collaborative et la presence d'un groupe de

  17. Investigaciones sobre la influencia del factor de forma y del rozamiento en procesos de compresión de piezas cilíndricas de aleación de aluminio AA 6082-T6 mediante técnicas numéricas y experimentales

    Directory of Open Access Journals (Sweden)

    Marín, M. M.

    2013-06-01

    Full Text Available The material characterization under similar load conditions to those applied during manufacturing is important in order to analyse Bulk Forming Compression Processes from a more realistic point of view. Open die forging of AA 6082-T6 aluminum alloy has been analysed by using experimental techniques and Finite Elements Method (FEM. The influence of the workpiece geometry on the effects that friction produces in typical process variables such as applied forces, contact pressures and stresses and strains in workpieces has been analysed by FEM simulation. It has been shown that higher shape factors of the initial workpiece geometry are recommended in such a way that friction effect is minimised. These results are interesting in order to decrease the required energy of the process and the tool wear, and could be used in further analysis of stamping processes.La caracterización de los materiales bajo similares condiciones de carga a las que se tienen durante su fabricación permite abordar el estudio de Procesos de Conformado por Deformación Plástica a Compresión (PCDPC desde un punto de vista más realista. La forja abierta de la aleación de aluminio AA 6082-T6 ha sido sometida a análisis, combinando técnicas experimentales y el Método de los Elementos Finitos (MEF. A través del modelo numérico se ha analizado la influencia de la geometría de la pieza en los efectos que el rozamiento provoca en variables típicas de estos procesos como las presiones aplicadas, presiones de contacto y tensiones y deformaciones en las piezas. Se ha demostrado que se debe elegir una geometría de pieza inicial con un factor de forma lo más elevado posible para minimizar el efecto del rozamiento. Estos resultados son de interés para disminuir la energía requerida en el proceso así como el desgaste de herramientas y podrían extrapolarse a procesos como la estampación.

  18. Bush v. Bin Laden: Effect of State Emotion on Perceived Threat is Mediated by Emotion Towards the Threat Agent (Bush vs. Ben Laden: l’Effet de l’Emotion etat sur la Menace Percue est Mediatisees par l’Emotion vis-a-vis de l’Agent Menacant)

    Science.gov (United States)

    2009-07-01

    auteurs ont mene une etude perception j emotion j experimentale afin d’examiner les effets d’etats emotionnels Specifi- ques ( peur et colere) et globaux... peur et colère) et de l’état émotionnel général sur la perception de la menace que représentent George W. Bush ou Oussama ben Laden. Les résultats ont

  19. Chronological study of beryllium plasma produced by a laser beam; Etude chronologique du plasma de beryllium cree par le faisceau d'un laser

    Energy Technology Data Exchange (ETDEWEB)

    Langer, Ph.; Tonon, G.; Durand, Y.; Buges, J.C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    de suivre l'evolution du plasma pendant toute la duree de l'impulsion laser (largeur a mi-hauteur 40 ns). Ce plasma, visible a partir de - 60 ns (l'origine des temps est prise au sommet de l'impulsion laser) subit une acceleration uniforme de - 30 a + 5 ns; a cet instant sa vitesse d'expansion est maximum et vaut 10{sup 7}cm/s, Des ions Be{sup +}, Be{sup 2+} et Be{sup 3+} (correspondant a un potentiel d'ionisation de 153 eV) sont emis par le plasma des sa creation et possedent une energie cinetique maximum de 1500 eV. L'etude spectroscopique du plasma a mis en evidence l'apparition de raies de recombinaison du beryllium une fois ionise et du beryllium excite a partir respectivement de + 70 ns et + 120 ns. Ces raies sont encore visibles au-dela de + 470 ns et + 720 ns. Des mesures interferometriques effectuees sur ce plasma nous ont revele que sa densite electronique n'est pas uniforme et decroit rapidement au fur et a mesure que l'on s'eloigne de la cible. Par exemple a 0,3 mm de la surface de la cible elle est respectivement de 2,3. 10{sup 18} e/cm{sup 3} et de 5,5. 10{sup 17} e/cm{sup 3} aux instants + 20 ns et + 40 ns. (auteurs)

  20. Experimental measurements and mathematics; Les mesures experimentales et les mathematiques

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, I.; Bruno, S.; Durand, O.; Gaillard, P.; Lagrange, J.M.; Lamy, F.; Peyrat, J.P. [CEA Bruyeres-le-Chatel, 91 (France); Choux, A.; Druoton, L.; Pascal, G.; Sulpice, F. [CEA Valduc, 21 - Is-sur-Tille (France); Busvelle, E.; Garnier, L. [Universite de Bourgogne, Lab. d' Electronique, Informatique et Image, 21 - Dijon (France); Gauthier, J.P. [Laboratoire des Sciences de l' Information et des Systemes, 83 - Toulon (France); Langevin, R. [Institut Mathematique de Bourgogne, 21 - Dijon (France)

    2011-01-15

    Many problems that appear in experimental works can be solved by using mathematical methods, from the conception phase to the interpretation of measurements. We illustrate the use of these methods at CEA-DAM by pointing out some examples in 3 typical domains: treatment of experimental data, geometrical controls of targets, and analysis of a huge quantity of data. (authors)

  1. Muestreo como un requisito fundamental en las ciencias experimentales

    Directory of Open Access Journals (Sweden)

    Badii, M. H.

    2004-01-01

    Full Text Available Se presentan los fundamentos básicos de muestreo, enfatizando los requisitos para determinar el tamaño óptimo de la muestra. Se discuten el muestreo absoluto y relativo y la comparación entre ellos. Se destaca la relevancia del tipo de distribución espacial en el diseño de muestreo y presenta varios modelos de uso actual para la determinación de ella. Se presentan de manera somera tres modelos de uso común, y finalmente, y por su relevancia práctica e económica, se discuten las cinco modalidades de muestreo secuencial.

  2. Caracterisation experimentale de la transmission acoustique de structures aeronautiques

    Science.gov (United States)

    Pointel, Vincent

    Le confort des passagers à l'intérieur des avions pendant le vol est un axe en voie d'amélioration constante. L'augmentation de la proportion des matériaux composites dans la fabrication des structures aéronautiques amène de nouvelles problématiques à résoudre. Le faible amortissement de ces structures, en contre partie de leur poids/raideur faible, est non favorable sur le plan acoustique, ce qui oblige les concepteurs à devoir trouver des moyens d'amélioration. De plus, les mécanismes de transmission du son au travers d'un système double paroi de type aéronautique ne sont pas complètement compris, c'est la raison qui motive cette étude. L'objectif principal de ce projet est de constituer une base de données pour le partenaire industriel de ce projet : Bombardier Aéronautique. En effet, les données expérimentales de performance d'isolation acoustique, de systèmes complets représentatifs d'un fuselage d'avion sont très rares dans la littérature scientifique. C'est pourquoi une méthodologie expérimentale est utilisée dans ce projet. Deux conceptions différentes de fuselage sont comparées. La première possède une peau (partie extérieure du fuselage) métallique raidie, alors que la deuxième est constituée d'un panneau sandwich composite. Dans les deux cas, un panneau de finition de fabrication sandwich est utilisé. Un traitement acoustique en laine de verre est placé à l'intérieur de chacun des fuselages. Des isolateurs vibratoires sont utilisés pour connecter les deux panneaux du fuselage. La simulation en laboratoire de la couche limite turbulente, qui est la source d'excitation prépondérante pendant la phase de vol, n'est pas encore possible hormis en soufflerie. C'est pourquoi deux cas d'excitation sont considérés pour essayer d'approcher cette sollicitation : une excitation mécanique (pot vibrant) et une acoustique (champ diffus). La validation et l'analyse des résultats sont effectuées par le biais des logiciels NOVA et VAONE, utilisés par le partenaire industriel de ce projet. Un des objectifs secondaires est de valider le modèle double paroi implémenté dans NOVA. L'investigation de l'effet de compression local du traitement acoustique, sur la perte par transmission d'une simple paroi, montre que cette action n'a aucun effet bénéfique notable. D'autre part, il apparaît que la raideur des isolateurs vibratoires a un lien direct avec les performances d'isolation du système double paroi. Le système double paroi avec peau composite semble moins sensible à ce paramètre. Le modèle double paroi de NOVA donne de bons résultats concernant le système double paroi avec une peau métallique. Des écarts plus importants sont observés en moyennes et hautes fréquences dans le cas du système avec une peau composite. Cependant, la bonne tendance de la prédiction au vu de la complexité de la structure est plutôt prometteuse. Mots-clés : Expérimental, avion, double paroi, panneaux composites, perte par transmission, transmission aérienne, transmission solidienne, isolateur vibratoire.

  3. The experimental facility of Tournemire; La station experimentale de Tournemire

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-10-01

    This document presents the underground facility of Tournemire (Aveyron, France). The Tournemire abandoned railway tunnel gives access to a 250 m thick Jurassic clay bed covered with 250 m of limestones. The main goal of the Tournemire project is the study of the mechanical properties and fracturing of a clay formation and of its ability to be used as a deep underground storage facility for radioactive wastes. The document comprises a general presentation brochure and a description of the geologic, tectonic, geomechanical and hydro-geochemical surveys carried out in the facility. (J.S.)

  4. Muestreo como un requisito fundamental en las ciencias experimentales

    OpenAIRE

    Badii, M. H.; F. Lopez Perez; H. Quiroz; Pazhakh, A. R.

    2004-01-01

    Se presentan los fundamentos básicos de muestreo, enfatizando los requisitos para determinar el tamaño óptimo de la muestra. Se discuten el muestreo absoluto y relativo y la comparación entre ellos. Se destaca la relevancia del tipo de distribución espacial en el diseño de muestreo y presenta varios modelos de uso actual para la determinación de ella. Se presentan de manera somera tres modelos de uso común, y finalmente, y por su relevancia práctica e económica, se discuten las cinco modalida...

  5. Contribution to the study of the geophysical behaviour of lead-210 by application of alpha spectrometry; Contribution a l'etude du comportement geophysique du plomb 210 par application de la spectrometrie alpha

    Energy Technology Data Exchange (ETDEWEB)

    Nezami, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-06-01

    A study of the changes in the lead-210 contents of rain-water and of water produced by melting polar ice has required the development of a method for dosing lead-210, an {alpha} emitter. This method is 40 times more sensitive than that which measures the lead-210 by bismuth-210, a ({beta} emitter. The first part of the report presents the study of a spectrometry using semiconductor detectors; a catalogue of a spectra shows the advantages of this method. In the second part will be found at first a new chemical separation method for polonium-210 and the results obtained with this method. The main results obtained on the geophysical behaviour of lead-210 are the following: - the monthly lead-210 and polonium-210 contents in rain water are approximately constant with time. - in the Gif-sur-Yvette region, the clean-up by 'dry fall-out' can attain 40 to 50 per cent of the total fall-out. - a study of Antarctic ice samples makes it possible to determine an annual accumulation rate equivalent to 13.8 cm of water and to show discrepancies in the periodic concentrations which correspond to the latest maxima of solar activity. - a balance is drawn up between the radon produced by the continents and the lead-210 fall-out. (author) [French] Une etude sur les variations de la teneur en plomb 210 des eaux de pluie et des eaux de fusion des glaces polaires a necessite la mise au point d'une methode de dosage du plomb 210 emetteur {alpha}. Cette methode permet d'obtenir une sensibilite quarante fois superieure a celle dosant le plomb 210 par le bismuth 210 emetteur {beta}. La premiere partie du travail presente l'etude de la spectrometrie {alpha} par detecteur a semiconducteurs, un catalogue de spectres {alpha} met en evidence les avantages de cette methode. Dans la deuxieme partie on trouvera en premier lieu une nouvelle methode chimique de separation du polonium 210 ainsi que les resultats obtenus grace a cette methode. Les principaux resultats sur le

  6. A comparative study of the {sup 90}Sr/Ca ratio in human diet and bone tissue; Etude comparee chez l'homme du rapport {sup 90}Sr/Ca dans l'alimentation et le tissu osseux

    Energy Technology Data Exchange (ETDEWEB)

    Coulon, R.; Madelmont, C. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1969-07-01

    A comparative study of both the evolution of strontium-90 content in the bones of individuals of different ages for the period 1962-1967 as related to calcium, and the corresponding diets allowed to establish the relationship between food contribution and the resulting bone burden. The study is mainly devoted to the group of adults for which a mathematical expression is proposed which allows for the exchangeable form of a skeletal calcium fraction turned over in less than a year from the dietary calcium, and the stabilized form constituting the larger part of bone tissue characterized by a slow turnover. Both the amount of the exchangeable fraction and the turnover rate of the stabilized fraction are determined for vertebrae and ribs. At birth, bone levels indicate that the calcium used for skeleton modelling during foetal life originates from both maternal diet and bone tissue and a value is given, to their relative significance. There appears a good relationship between bone levels in infants from 6 months to 1 year of age and their diets. The physiological parameters particular to this age are quantified. (authors. [French] L'etude comparee de l'evolution de la teneur en strontium 90 rapportee au calcium, mesuree dans les os d'individus a differents ages durant la periode 1962-1967 et celle du regime alimentaire correspondant, a permis d'etablir la relation qui existe entre l'apport du a l'alimentation et la charge osseuse qui en resulte. L'essentiel de l'etude est consacre au cas des adultes. Pour ce groupe la formulation mathematique proposee tient compte de la presence de la forme echangeable d'une fraction du calcium osseux, renouvelee en moins d'un an a partir du calcium alimentaire, et de la forme stabilisee, constituant la majeure partie du tissu osseux, caracterisee par un renouvellement lent. L'importance de la fraction echangeable, ainsi que le taux de renouvellement de la fraction stabilisee sont

  7. Le changement comme tradition dans la recherche et la formation a la recherche en biotechnologie et en peripherie Etude de cas en sciences de la sante, sciences naturelles et genie

    Science.gov (United States)

    Bourque, Claude Julie

    Le champ de la recherche scientifique et de la formation a la recherche est traverse depuis quelques dizaines d'annees par plusieurs courants et discours associes au changement, mais peu de travaux empiriques permettent de comprendre ce qui change concretement. C'est la contribution originale de cette these au champ de l'education, plus specifiquement a l'etude sociologique de l'enseignement superieur ou sont concentrees les activites liees a la triade thematique du programme doctoral dans lequel elle a ete produite : recherche, formation et pratique. L'enquete-terrain a ete realisee en 2009 et 2010 aupres de 808 repondants affilies a 60 etablissements au Quebec et a produit un vaste materiau de nature mixte (donnees quantitatives et qualitatives). Un portrait de la nebuleuse biotechnologique qui touche les secteurs des sciences de la sante, des sciences naturelles et du genie a ete realise. Ce domaine concerne des dizaines de disciplines et se revele de nature transdisciplinaire, mais les pratiques n'y sont pas davantage marquees par le changement que celles d'autres domaines connexes. Les dynamiques sociales ont fait l'objet d'analyses comparatives dans quatre contextes: le choix des programmes, des objets et des methodes, le financement, la diffusion et la planification de la carriere. Les resultats indiquent que les echanges entre les agents traditionnellement situes au coeur des activites de recherche dominent ces dynamiques dans tous les contextes etudies. L'etude des representations au fondement des pratiques a revele l'existence de trois ecoles de pensee qui coexistent dans le champ scientifique: academique, pragmatique et economiste. Ces ecoles permettent de categoriser les agents en fonction des zones de fractures qui marquent leurs oppositions tout en identifiant ce qu'ils ont en commun. Les representations et les pratiques liees a la formation temoignent d'un habitus plutot homogene, alors que les contradictions semblent plus souvent ancrees dans des

  8. Feasibility study for the installation of a small hydro electric power plant; Etude de faisabilite. Petite centrale hydro-electrique au lieu dit 'Sous les Roches' a Sonceboz

    Energy Technology Data Exchange (ETDEWEB)

    Tissot, N. [MHyLab, Mini-Hydraulics Laboratory, Montcherand (Switzerland); Hausmann, H. [Hans Hausmann, Bevilard (Switzerland)

    2003-07-01

    This report for the Swiss Federal Office of Energy presents a technical, economical and ecological analysis of the feasibility of a small hydroelectric power plant at Sonceboz, in the Swiss Jura mountains. The power of the planed plant would typically be 500 kW for a water head of about 10 m. The study shows that, compared to one single turbine, a pair of Kaplan type turbines would be operational over a larger range of the river's water flow rate. This solution would be a little bit more costly but offer more flexibility for maintenance. Two maximum water flow rates are considered, 4.5 and 6 m{sup 3}/s respectively. According to the economical study, done with current electric kWh prices, both configurations are viable while the largest flow rate leads to a larger profit. The report is rounded up by a sensitivity analysis considering variations in annual power generation, electro-mechanical and construction cost as well as turbine efficiency. It indicates that this last factor could be crucial for the overall profitability. [French] Ce rapport est le resultat detaille de l'analyse technico-economique et ecologique de faisabilite de la realisation d'une petite centrale hydroelectrique basse chute qui pourrait exploiter une denivellation d'environ 10 m pour une puissance de l'ordre de 500 kW pres de Sonceboz dans le Jura suisse. L'etude montre que le couplage de deux turbines Kaplan offrirait une possibilite de fonctionnement sur une plus grande plage de flux ainsi qu'une plus grande flexibilite de maintenance, ceci pour un cout legerement superieur a l'option a une seule turbine. Les debits de 4.5 et 6 m{sup 3}/s sont consideres. L'etude economique montre que le debit de 6 m{sup 3}/s est plus rentable au prix de vente actuel du kWh. L'article se termine par une analyse de sensibilite sur les incertitudes concernant la production annuelle, les prix de l'electromecanique et du genie civil et le rendement des

  9. Contribution to the study of 14 MeV neutron scattering by {sup 12}C using a time-of-flight spectrometer (1963); Contribution a l'etude de la diffusion des neutrons de 14 MeV par {sup 12}C, a l'aide d'un spectrometre a temps de vol (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Perrin, P. [Commisariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-07-15

    Experimental measurements of 14 MeV fast neutrons scattering by {sup 12}C by time-flight spectrometer, with a 1.7 n. sec over-all resolution. The excitation of the 7.65 MeV level is observed. (author) [French] Etude experimentate de la diffusion par {sup 12}C des neutrons rapides de 14 MeV a l'aide d'un spectrometre de resolution totale de 17 n/s. Observation de l'excitation du niveau 0+ de 7,65 MeV. (auteur)

  10. Fast neutron breeder reactor Rapsodie - situation of physics, hydraulic, thermal and dynamics studies and studies of stability early in 1963; Pile rapide rapsodie - point des etudes neutroniques, hydrauliques, thermiques et dynamiques et des etudes de stabilite au debut de l'annee 1963

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1964-07-01

    ) [French] Au debut de 1963, il a ete necessaire de faire un choix entre les deux combustibles etudies pour Rapsodie: l'alliage UPuMo avec double gainage Nb et acier inoxydable et l'oxyde mixte UO{sub 2}-PuO{sub 2}. Ce rapport donne les resultats des etudes menees avec les deux types de combustible. On rappelle d'abord les differents modeles qui ont ete etudies et on donne une description detaillee de coeurs alliage et oxyde tels qu'ils sont envisages au debut de 1963. On rapporte ensuite les principales caracteristiques neutroniques des deux coeurs: flux et spectre des neutrons, valeur des barres de securite - compensation, economie des neutrons, puissance specifique, fraction effective des neutrons retardes, temps de vie des neutrons prompts, coefficients de reactivite. On decrit les etudes et essais hydrauliques qui ont ete faits a propos de ces deux coeurs. On discute les criteres qui ont ete a l'origine des calculs de debits. On donne les resultats des essais de pertes de charge, de soulevement des assemblages, de vibration et d'ecoulement fin entre les aiguilles. On discute les constantes utilisees pour les calculs thermiques et on donne les temperatures maximales du sodium et des combustibles alliage et oxyde, les majorations dues aux points chauds et la limitation du taux de combustion de l'aiguille oxyde ayant pour origine la pression des gaz de fission. On rapporte les hypotheses qui ont ete utilisees pour les calculs dynamiques et l'on decrit les differents incidents qui ont ete etudies. On donne les resultats des calculs, pour chaque incident et pour chaque combustible et l'on montre que l'on peut eviter la fusion du combustible ou l'ebullition du sodium, meme dans le cas des hypotheses les plus pessimistes, en agissant sur les caracteristiques de la pile (valeur de la barre de pilotage ou puissance de la pile avec un seul circuit de refroidissement). La stabilite de la pile a ete evaluee avec les hypotheses

  11. Physical and genetic map of 5q31: use of fluorescence in situ hybridization data to identify errors in the CEPH database. Centre d'Etude de Polymorphisme Humain.

    Science.gov (United States)

    Westbrook, C A; Le Beau, M M; Neuman, W L; Keinanen, M; Yamaoka, L H; Speer, M C; Espinosa, R; Nakamura, Y; Williamson, R; Mullan, M

    1994-01-01

    Chromosome 5, band q31, contains the genes responsible for a number of interesting genetic and malignant diseases, as well as many cloned genes. To prepare a high-resolution map of this region, eight anonymous DNA markers were mapped by combining genetic data derived from linkage analysis, with physical data obtained using two-color fluorescent in situ hybridization (FISH). Probe order was determined by FISH on metaphase cells, supplemented with interphase analysis, while genetic distance and likely order were determined by multipoint linkage analysis using genotype data from Centre d'Etude de Polymorphisme Humain (CEPH) pedigrees. Discrepancies between the genetic and physical maps suggested that there was a high rate of genotyping errors in the CEPH data for these markers, and prompted a statistical analysis to identify these errors. By assuming a known physical order (as determined by FISH) it was possible to identify markers which had the greatest degree of error. The average typing error was estimated at 1.8%, but several markers had much higher error rates; a 14% error rate was predicted for one locus, which was subsequently confirmed by retyping. The analysis led to the preparation of a revised map spanning 24.5 cM of 5q31. This study illustrates the power of FISH to determine physical order over a wide genomic distance, and demonstrates how order can be used as an adjunct to linkage analysis, particularly in the identification of genotyping errors.

  12. Five-year outcome of a stroke cohort in Martinique, French West Indies: Etude Réalisée en Martinique et Centrée sur l'Incidence des Accidents vasculaires cérebraux, Part 2.

    Science.gov (United States)

    Chausson, Nicolas; Olindo, Stéphane; Cabre, Philippe; Saint-Vil, Martine; Smadja, Didier

    2010-04-01

    Limited information exists on stroke among black populations outside the United States and United Kingdom. Part 1 of the Etude Réalisée en Martinique et Centrée sur l'Incidence des Accidents vasculaires cérebraux (ERMANCIA) provided strong epidemiologic data on the incidence of first-ever stroke in a black Caribbean population and showed a 40% greater incidence of stroke in Martinique than in continental France. In ERMANCIA part 2, we evaluated the long-term outcomes of our cohort. Survivors of a first stroke from this prospective, community-based, stroke incidence study were reassessed at 5 years according to standardized procedures and criteria, including the modified Rankin scale, Barthel Index, Montgomery-Asberg Depression-Rating Scale, Mini-Mental State Examination, treatment compliance, and blood pressure control. Of the 293 survivors of the original 580 (50.5%) patients who were still alive 5 years after stroke, 262 (89.4%) were assessed. Among these survivors, 66.4% were functionally independent and 43% were completely autonomous for activities of daily living, but 25.8% were depressed and 58.9% were cognitively impaired. Only 50 of 170 (29.4%) of the hypertensive patients achieved their target blood pressure. These results highlight the very poor blood pressure control and the very high rate of cognitive impairment in Martinican patients after stroke. As a consequence, a poststroke prevention network was established in Martinique.

  13. The synthesis and spectroscopic study of stable free radicals related to piperidine-n-oxyl, including a stable bi-radical; Syntheses et etudes spectroscopiques de radicaux libres piperidiniques et d'un biradical stable, du type nitroxyde

    Energy Technology Data Exchange (ETDEWEB)

    Briere, R. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires, Laboratoire de chimie organique physique

    1967-06-01

    A new synthesis of di-tert-butyl nitroxide using the reaction between tert-butyl magnesium chloride and nitro-tert-butane is presented in the first section. Synthesis and investigation of stable free piperidine-N-oxyl radicals are described in the second section. All these nitroxides have been characterised by their I. R., U. V. and E. P. R. absorption spectra. The final section contains a description of the synthesis of a stable bi-radical of the nitroxide type by condensation of 2,2, 6, 6-tetramethyl-piperid-4-one-l-oxyl with hydrazine. (author) [French] La premiere partie expose une nouvelle methode de synthase du di-t-butyl nitroxyde, par action d'halogenures de t-butyl magnesium sur le nitro-t-butane (Rdt maximum 45 pour cert, purete 86 pour cent). Une etude de radicaux. libres stables pipericliniques est faite dans une seconde partie. Ces composes sont obtenus par oxydation de derives de la triacetonamine. Les caracteristiques spectroscopiques ultra-violette, infra-rouge, et paramagnetique electronique de ces radicaux sont donnees. La grande inertie chimique du groupement nitroxyde a permis la syn-these d'un biradical stable par formation d'azine d'une cetone radicalaire, ce qui fait 1'objet de la troisieme partie. (auteur)

  14. Study relating to the physico-chemical behaviour of heavy water in nuclear reactors; Etudes relatives au comportement physico-chimique de l'eau lourde dans les reacteurs nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Chenouard, J.; Dirian, G.; Roth, E.; Vignet, P.; Platzer, R. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1959-07-01

    Chemical and isotope pollution, and radiolytic decomposition are the two most important ways in which heavy water becomes degraded in nuclear reactors. Chemical pollution has led to the creation of ion exchange purification loops specially designed for reactors: the report contains a description in detail of the application of this purification method in CEA research reactors, including the analysis required, results obtained, and their interpretation. The intelligence obtained on radiolytic decomposition with the same facilities is also discussed, as well as the recombination apparatus and control equipment utilized. Finally, investigation to date in the CEA on recombination circuits for power reactors is also discussed. (author) [French] Parmi les degradations subies par l'eau lourde dans les reacteurs nucleaires, les deux plus importantes sont la pollution chimique et isotopique et la decomposition radiolytique. La pollution chimique a conduit a mettre au point pour le cas particulier des reacteurs, des circuits d'epuration par echange d'ions. On decrit ici en detail la mise en oeuvre de cette methode dans les reacteurs de recherche du CEA; les controles qu'elle necessite, les resultats obtenus et leur interpretation. En ce qui concerne la dissociation radiolytique de l'eau, les renseignements obtenus sur ces memes reacteurs sont communiques, ainsi que les details des dispositifs de recombinaison et des moyens de controle. Enfin, on fait le point des etudes poursuivies au CEA sur ces memes problemes de recombinaison dans le cas des reacteurs de puissance. (auteur)

  15. Contribution to the study of porous or very finely divided alumina; Contribution a l'etude des alumines poreuses ou tres finement divisees

    Energy Technology Data Exchange (ETDEWEB)

    Juillet, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-12-15

    deficit en aluminium apres traitement a 700 deg C entrainant l'apparition des proprietes de semi-conducteur n puis p. Une alumine cristallisee delta sous forme do grains spheriques non poreux soumise a une compression de 1 a 5 t/cm{sup 2} presente egalement une non-stoechiometrie a deficit d'oxygene ou d'aluminium. Aucun de ces phenomenes n'a pu etre enregistre avec l'echantillon non soumis a la compression. L'influence favorable de l'oxygene dans le processus de recristallisation de l'alumine amorphe et dans la transformation delta-alpha de l'alumine cristallisee a ete mise en evidence, De plus, les contraintes developpees par compression de l'alumine delta permettent sa transformation en phase alpha dans l'air a une temperature inferieure a celle necessaire pour observer le meme phenomene dans l'alumine delta non comprimee. L'afumine amorphe subit un frittage intragranulaire des 500 deg C et un frittage intergranulaire a 1 000 deg C. Seul ce dernier s'observe pour l'alumine en grains spheriques. Pour cette derniere les contraintes developpees par la compression abaissent de 100 deg C le seuil de ce frittage par rapport a la temperature necessaire pour observer ce phenomene avec l'echantillon non comprime. Le taux de frittage d'un comprime d'alumine cristallisee depend, en plus, de la vitesse de la mise en temperature. L'ensemble de cette etude tend a montrer que des proprietes nouvelles, ou du moins inhabituelles de l'etat solide peuvent etre observees s'il est fait appel a des solides desorganises ou encore cristallises mais dotes d'une importante surface specifique et soumis a des contraintes. (auteur)

  16. Study of atmospheric tritium transfers in lettuce: kinetic study, equilibrium and organic incorporation during a continuous atmospheric exposure; Etude des transferts du tritium atmospherique chez la laitue: Etude cinetique, etat d'equilibre et integration du tritum sous forme organique lors d'une exposition atmospherique continue

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, C.

    2009-11-30

    This thesis has explored the mechanisms of tritium 'absorption and incorporation in a human-consumed plant, lettuce (Lactuca sativa L.), due to atmospheric exposure. Foliar uptake appears to play a key role in absorption of tritium as tissue free water tritium. Whatever the development stage and the light conditions, the specific activity in tissue free water reaches that of water vapour in air in several hours. The specific activity ratio is then about 0, 4. The time to reach equilibrium in soil is over 24 hours in most cases: the specific activity ratio ranges then 0, 01 to 0, 26. Incorporation rate of tissue free water tritium as organically-bound tritium has been estimated to 0, 13 to 0, 16 % h-l in average over the growing period of the plant, but marked variations are observed during growth. In particular, a significant increase appeared at the exponential growth stage. Deposition and diffusion of tritium in soil lead to significant OBT activities in soil. Results globally indicate equilibrium between the different environmental compartments (air, soil, plant). However, some experiments have revealed high OBT concentrations regarding atmospheric level exposure and ask for a possible phenomenon of local tritium accumulation in OBT for particular conditions of exposure. (author) [French] Ce travail de these a concerne l'etude des phenomenes d'absorption et d'incorporation sous forme organique du tritium dans un vegetal de consommation courante, la laitue (Lactuca sativa L.), en reponse a une exposition atmospherique. Il apparait que la voie foliaire joue un role primordial dans l'absorption du tritium au sein de l'eau tissulaire des plants. Quels que soient le stade de developpement des plants et les conditions d'eclairement, le temps necessaire pour atteindre l'equilibre des concentrations dans l'eau libre et dans la vapeur d'eau de l'air est de plusieurs heures; le rapport des concentrations est alors de

  17. Short-term effects of habitat fragmentation on the abundance and species richness of beetles in experimental alfalfa micro-landscapes Efectos a corto plazo de la fragmentación del hábitat sobre la abundancia y riqueza de especies de coleópteros en micro-paisajes experimentales de alfalfa

    Directory of Open Access Journals (Sweden)

    AUDREY A. GREZ

    2004-09-01

    , instead, it could favor the biota, at least at short time scalesLa pérdida y fragmentación del hábitat han sido consideradas como las principales causas de la disminución de biodiversidad. La pérdida de hábitat es una disminución del hábitat utilizable por los organismos y la fragmentación es un cambio en la configuración espacial del paisaje, donde los fragmentos remanentes quedan relativamente aislados entre sí. Trabajos teóricos recientes indican que los efectos de la pérdida de hábitat son más importantes que los de la fragmentación, sin embargo existen pocos estudios experimentales que evalúen por separado ambos procesos. Para estudiar los efectos de la fragmentación per se sobre la abundancia y riqueza de especies de coleópteros epigeos, se crearon 15 micro-paisajes de alfalfa de 30 x 30 m distribuidos en tres bloques. Doce de ellos se fragmentaron removiendo el 84 % del hábitat, dejando cuatro ó 16 fragmentos separados por 2 ó 6 m. Entre diciembre del 2002 y abril del 2003, antes y después de la fragmentación, se muestrearon los coleópteros mediante trampas Barber. Se capturó un total de 8.074 coleópteros de 75 especies pertenecientes a 16 familias. El tipo de paisaje no afectó la abundancia de coleópteros, sólo Anthicidae fue más abundante en los paisajes de 4 fragmentos separados por 2 m y fue más abundante en la matriz. El resto de de las familias fue más abundante en los fragmentos, significativamente Carabidae y Lathridiidae. La riqueza de especies por trampa y por paisaje fue mayor en los paisajes con 16 fragmentos separados por 6 m, concentrándose en los fragmentos. Contrario a lo descrito en la mayor parte de la literatura, la fragmentación no afectó negativamente la abundancia y riqueza de especies de coleópteros epigeos asociados a alfalfa. Más bien, fragmentos de alfalfa más pequeños y aislados ofrecieron un refugio de hábitat para la biodiversidad de coleópteros epigeos. Estos resultados concuerdan con los

  18. Study of the artificial radioactivity of the marine medium using gamma spectrometry (1962-1966); Etude de la radioactivite artificielle du milieu marin par spectrometrie gamma (1962-1966)

    Energy Technology Data Exchange (ETDEWEB)

    Chesselet, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    The results described in this study are relative to the artificial radioactivity of such elements as zirconium-95, niobium-95, ruthenium-103, ruthenium-106, cerium-141, cerium-144 and praseodymium-144 which were present in the atmospheric fallout between 1962 and 1964, and their incidence in superficial marine waters. Various physical, chemical or biological processes are studied by a high sensitivity gamma ray spectrometry technic, using those radioelements as 'tracers'. The change of state in sea water of an important fraction (about 50 per cent) of the radioactive particles going into the soluble phase - this phenomenon was not expected for those radioelements - controls the processes of accumulation in the planktonic biomass and the diffusion towards deeper waters. On the other hand, an 'in situ' spectrometry method is described. It enables the direct measurement in the sea of very low concentrations of some gamma ray emitters. The application of this method has made possible to carry out numerous observations in the surface waters of the Western Mediterranean sea and in the Bay of Biscay. It is shown that the mixing depth is closely connected to the depth of the thermocline. An accumulation process at this level is observed. The diffusion coefficients are similar to the thermal turbulent coefficient. The existence during several months of 'compartments' is established for the surface waters of the Bay of Biscay. From the establishment of the budget of fall-out, a comparative study shows that the rate of radioactive fallout on the maritime zone considered is always two to three times higher than on the neighbouring continental regions. Several explanations of this phenomenon are discussed. (author) [French] Les resultats decrits dans cette etude concernent la radioactivite artificielle sous forme de zirconium-95, niobium-95, ruthenium-103, ruthenium-106, cerium-141, cerium-144 et praseodyme-144 apportee par la retombee

  19. Contribution to the studies on the mineral content of plant material through radioactivation analysis; Contribution a l'etude de la composition minerale des matieres vegetales au moyen de l'analyse par radioactivation

    Energy Technology Data Exchange (ETDEWEB)

    Fourcy, A. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1968-03-15

    Radioactivation analysis is by its great sensibility or its rapidity quite helpful in plant biology and agronomy. Specific composition of plants and results to obtain in biological experimentation have needed a practical research on analytical methods for plant materials, using for radioactivation swimming-pool reactor neutrons and 14 MeV neutrons from a generator. Dosage process for 25 elements is exposed, taking account of the interest of the analysis for each element, the average amount occurring in plants and the result obtained. Many applications are developed, concerning nutrition physiology, genetics, parasitology, toxicology, control of manufactured agricultural and pharmaceutical products industrial and pesticides residues, ecology, radioecology and biochemistry. (author) [French] L'analyse par radioactivation, par sa grande sensibilite ou sa rapidite, est susceptible de rendre de nombreux services en biologie vegetale et en agronomie. La composition particuliere des plantes et les buts recherches dans l'experimentation ont exige une etude concrete des methodes d'analyse propres a la matiere vegetale en utilisant, pour la radioactivation, soit un reacteur de type piscine a eau legere, soit un accelerateur generateur de neutrons de 14 MeV. Le mode de dosage de 25 elements est expose en tenant compte de l'interet de l'analyse de chaque element, des teneurs moyennes rencontrees dans les plantes, et du resultat atteint. De nombreuses applications sont developpees qui touchent a la physiologie de la nutrition, la genetique, la parasitologie, la toxicologie, le controle des fabrications, les pollutions industrielles, l'ecologie, la radioecologie et la biochimie. (auteur)

  20. Study of the solubility of plutonyl nitrate with a view to its extraction by a solvent; Etude de la solubilite du nitrate de plutonyle en vue de son extraction par solvant

    Energy Technology Data Exchange (ETDEWEB)

    Vergnaud, G. [Commissariat a l' Energie Atomique, Fontenay aux Roses (France). Centre d' Etudes Nucleaires

    1965-09-01

    The research covers the determination of the partition coefficient of plutonyl nitrate and their application to the industrial treatment of plutonium. The solvent used is a tri-n-butyl phosphate solution diluted to 30 per cent in dodecane. The parameters which have been studied and which can affect the extraction of the plutonyl nitrate are: the plutonyl nitrate concentration; the nitric acid concentration; the uranyl nitrate concentration; the tetravalent plutonium nitrate concentration. The industrial application has been studied using a battery of mixer-separators. The operational conditions are defined in the case of a conventional plutonium separation plant. The results obtained, for a higher plutonyl nitrate concentration than that actually planned, are satisfactory and encouraging as far as the operation is concerned. Only the presence of polymerized tetravalent plutonium can adversely affect the satisfactory extraction of the plutonium. (author) [French] L'etude porte sur les coefficients de partage du nitrate de plutonyle et leur application a l'elaboration industrielle du plutonium. Le solvant utilise est une solution de phosphate de tri-n-butyle, dilue a 30 pour cent dans le dodecane. Les parametres etudies et pouvant influencer l'extraction du nitrate de plutonyle, par ce solvant, sont: concentration du nitrate de plutonyle; concentration de l'acide nitrique; concentration du nitrate d'uranyle; concentration au nitrate de plutonium tetravalent. L'application industrielle est etudiee au moyen d'une batterie de melangeurs-decanteurs. Les conditions operatoires sont definies d'apres un schema classique d'usine de separation de plutonium. Les resultats obtenus, pour une concentration du nitrate de plutonyle superieure a celle reellement prevue, sont satisfaisants et encourageants pour l'exploitation. Seule, la presence de plutonium tetraralent polymerise, peut nuire a une bonne extraction du plutonium

  1. Spectrophotometric study of the complexes of cerium and uranides with diethylenetetraaminepentaacetic acid (DTPA); Contribution a l'etude de la complexation du cerium et des uranides par l'acide diethylenetetraminepentaacetique (DTPA)

    Energy Technology Data Exchange (ETDEWEB)

    Hafez, M.B. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-03-01

    A spectrophotometric determination was made of the complexes of cerium and uranides in their different degrees of oxidation with diethylenetriaminepentaacetic acid (DTPA). Two physico-chemical states, the ionic and hydrolysis ones, were considered. In the former case, we studied the influence of the pH on the formation of the complex, and whenever the complexes were stable, we determined the molecular ratio and calculated their stability constants. In the latter case, we studied the conditions of solubilization of the precipitate by formation of complexes soluble in water as a function of pH, age of the precipitate and time of precipitate-chelate contact. (authors) [French] Etude spectrophotometrique de la complexation du cerium et des uranides (uranium, neptunium, plutonium et americium) dans leurs differents etats d'oxydation par l'acide diethylenetriaminepentaacetique (DTPA). Deux etats physicochimiques ont retenu notre attention, l'etat ionique et l'etat precipite d'hydrolyse. Dans le premier cas, nous avons etudie l'influence du pH sur la formation du complexe, et dans tous les cas ou le complexe est stable, nous avons determine le rapport moleculaire (5) [element]/[chelatant] du complexe forme et nous avons calcule leurs constantes de stabilite. Dans le deuxieme cas, l'etat de precipite d'hydrolyse, nous avons etudie les conditions de solubilisation du precipite, par formation du complexe, en fonction du pH, de l'age du precipite et du temps de contact precipite - chelatant. (auteurs)

  2. Contribution to the study of the biological properties of compounds labeled with radio-chromium {sup 51}Cr; Contribution a l'etude des proprietes biologiques des composes marques au radiochrome {sup 51}Cr

    Energy Technology Data Exchange (ETDEWEB)

    Ingrand, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-15

    Among the radioisotopes commonly used in biology and medicine which are controlled Individually in the Radioelement Departement of the Saclay Nuclear Research Centre before being sent to the users, the author has chosen chromium 51 incorporated in inorganic salts or in organic substrates for a study of the biological properties of the compounds. In the first part, he has compared the pathways followed by the radioactive sodium chromate and chromic chloride mixed with blood or given to the whole animal, the object being to determine whether a reduction of hexavalent chromium occurs, both in vitro and in vivo. In the second part, the author has tried to show the validity of using, various substrates labeled with chromium 51, red cells, haemoglobin, plasma proteins and cytochrome c. The results obtained have contributed to underline the interest of using such compounds for biological applications. (author) [French] Parmi les radioisotopes d'utilisation courants en biologie et en medecine qui sont l'objet d'un controle particulier dans le Departement des Radioelements du Centre d'Etudes Nucleaires de Saclay avant leur diffusion aux utilisateurs, l'auteur a choisi le chrome 51 incorpore a des sels mineraux ou a des substrats organiques, afin d'en etudier les proprietes biologiques. Dans la premiere partie, il a compare le sort du chromate de sodium et du chlorure chromique radioactifs melanges a du sang ou administres a l'animal entier en s'efforcant de mettre en evidence une reduction du chrome hexavalent aussi bien in vitro qu'in vivo. Dans la deuxieme partie, il a cherche a etablir la validite de l'emploi de differents substrats marques au chrome 51, l'hematie, l'hemoglobine, les proteines plasmatiques et le cytochrome c. Les resultats obtenus ont permis de souligner le reel interet des applications biologiques des composes marques par le radioisotope. (auteur)

  3. Study of the structure of light neutron rich nucleus with the Tonnerre array; Etude de la structure de noyaux legers riches en neutrons a l'aide du multidetecteur Tonnerre

    Energy Technology Data Exchange (ETDEWEB)

    Pietri, St

    2003-06-01

    This work concern the technical development made on the multidetector TONNERRE and the study of the {sup 34}Si nucleus by a complete beta-neutron-gamma spectroscopy. In the first part various tests performed on modules of the detector in the 'Centre d'Etude de Bruyere le Chatel' are presented. A modification of the embassies of the photomultipliers tubes allows to gain more than 50% in the neutron efficiency and to obtain a threshold lower than 300 keV for the neutron energy. A complete C++ simulation of the neutron propagation in the array was carried out. It explains that the slow component of the light output of the scintillator may be responsible of the shape of the time-of-flight spectrum. The second part of these report presents the experiment devoted to the study of the structure of the {sup 34}Si from the beta decay of the {sup 34}Al. It was performed at the GANIL facility using the TONNERRE array and germanium of ENOGAM. The {sup 34}Al was produced by projectile fragmentation of a {sup 36}S beam of 50 MeV/A in a target of {sup 9}Be. A complete beta scheme of the {sup 34}Al is proposed. Eight neutron lines following the {sup 34}Al decay were observed for the first time. Finally we suggest that a monopolar transition could occur in the {sup 34}Si nucleus signing a O{sup +}{sub 2} state at 2133 keV. (author)

  4. Influence of a hydrostatic pressure on the diffusion in metals having a cubic structure; Contribution a l'etude de l'influence de la pression hydrostatique sur la diffusion dans les metaux cubiques

    Energy Technology Data Exchange (ETDEWEB)

    Beyeler, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    In view of obtaining informations on the structure of vacancies. We have determined, by diffusion experiments under high pressure, the activation volumes for self diffusion in different face centered cubic metals: silver, gold, copper, aluminium and in body centered cubic uranium (gamma phase). Activation volumes for noble metals diffusion in aluminium have also been investigated. The experimental results on gold, silver and copper are in good agreement with most of the theoretical models. The estimated activation volume for gamma uranium seems to indicate a vacancy mechanism.The results on aluminium for both self and impurity diffusion agree quite well with Friedel's theoretical predictions. [French] Pour preciser la structure des lacunes, on a, par des etudes de diffusion sous haute pression determine les volumes d'activation correspondant a l'autodiffusion dans des metaux de structure cubique face centree: argent, or, cuivre et aluminium et dans un metal de structure cubique centree: l'uranium gamma. On a egalement determine les volumes d'activation pour l'heterodiffusion des metaux nobles dans l'aluminium. Les resultats obtenus pour l'or, l'argent et le cuivre sont en accord avec la plupart des modeles theoriques classiques. Le volume d'activation d'autodiffusion evalue pour l'uranium gamma est compatible avec une diffusion par lacune. Les resultats concernant l'aluminium et l'heterediffusion des metaux nobles dans l'aluminium verifient assez bien les previsions theoriques de Friedel. (auteur)

  5. Contribution to the theoretical study of order-disorder phenomena in the electrical properties of alloys (1963); Contribution a l'etude theorique des phenomenes d'ordre dans les proprietes electriques des alliages (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Beal, M.T. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1963-07-01

    We have study theoretically the ordering of alloys and its influence an electrical resistivity. We have looked at the cases of concentrated, non magnetic alloys such as Cu Zn {beta} or Cu{sub 3}Au and of diluted, magnetic alloys such as noble matrix with rare earth impurities. In both cases, a simple method of molecular field with nearest neighbour interactions is used. Scattering cross sections are calculated with free electrons and Born approximation. The electrical properties are described with a good accuracy by single diffusions on each center (long range order). But some anomalies near to the ordering temperature are caused by double diffusions on pairs of interacting atoms or spins (local order). (author) [French] On presente une etude theorique des phenomenes d'ordre et de leur influence sur les proprietes electriques des alliages. Deux cas sont envisages: celui des alliages non magnetiques concentres, tels que Cu Zn {beta} ou Cu{sub 3}Au et celui d'alliages magnetiques tres dilues du type matrice noble impuretes de terres rares. Dans les deux cas on utilise une methode simple de champ moleculaire avec interactions entre plus proches voisins seulement. Les sections efficaces de diffusion sont calculees dans un modele d'electrons libres et dans l'approximation de Born. Les proprietes electriques sont decrites en premiere approximation par les diffusions simples sur chaque atome ou spin (ordre a longue distance). Mais elles presentent des anomalies a la temperature d'ordre dues aux diffusions doubles sur des paires d'atomes ou de spins plus proches voisins (ordre local). (auteur)

  6. Study of the long-term values and prices of plutonium; a simplified parametrized model; Etude des valeurs et des prix du plutonium a long terme; un modele parametre simplifie

    Energy Technology Data Exchange (ETDEWEB)

    Gaussens, J.; Paillot, H. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    The authors define the notions of use values and price of plutonium. They give a 'simplified parametrized model' simulating the equilibrium of the offer and the demand in time, concerning the plutonium and the price deriving from the relative scarcity of this metal, taking into account the technical and economic operating parameters of the various reactors confronted. This model is simple enough to allow direct computations and establish clear relations between the various parameters. The use of the linear programmes method allows on the other hand a wide extension of the model. This report includes three main parts: I - General description of the study (without detailed calculations) II - Mathematical development of the simplified parametrized model and application (the basic data and the results of the calculations are given) III - Appendices (giving the detailed computations of part II). (authors) [French] Les auteurs definissent les notions de valeurs d'usage et de prix du plutonium. Ils donnent un 'modele parametre simplifie' simulant l'equilibre de l'office et de la demande dans le temps concernant le plutonium et le prix qui decoule de la rarete relative de ce metal, compte tenu des parametres techniques et economiques de fonctionnement des divers reacteurs en presence. Ce modele est suffisamment simple pour permettre des calculs manuels et etablir des liaisons claires entre les divers parametres. L'utilisation de la technique des programmes lineaires permet par ailleurs une extension considerable du modele. Cette note comprend trois parties: I - Expose general de l'etude (sans expose du detail des calculs) II - Developpement mathematique du modele parametre simplifie et application (on precise les donnees de base et le resultat des calculs) III - Annexes (donnant le detail des calculs de la partie II). (auteurs)

  7. Study of the neutron strength function and of the diffusion radius as a function of mass number; Etude de la fonction densite de neutron et du rayon de diffusion en fonction du nombre de masse

    Energy Technology Data Exchange (ETDEWEB)

    Morgenstern, J. [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires

    1968-09-01

    The strength functions S{sub 0} and S{sub 1}, and the scattering length R' are studied. The values of S{sub 0}, S{sub 1} and R' are obtained by shape analysis of the individual resonances observed in total neutron cross-section measurements. These measurements were performed at the Saclay 45 MeV linac by the time of flight method. The best resolution achieved was equal to 0.19 ns/m. We have particularly studied the nuclei around number of mass A = 50, 90, 140 and 200. The experimental values of S{sub 0}, S{sub 1} and R' are compared with optical model calculations. A fairly good agreement is obtained using an optical potential with surface absorption. (author) [French] Nous etudions les fonctions densite S{sub 0} et S{sub 1} ainsi que le rayon de diffusion R'. Les valeurs de S{sub 0}, S{sub 1} et R' sont determinees a partir de l'analyse de forme des resonances individuelles observees lors de la mesure de la section efficace neutronique totale. Cette mesure a ete faite aupres de l'accelerateur lineaire d'electrons de 45 MeV de Saclay par la methode du temps de vol. La meilleure resolution atteinte etait egale a 0.19 ns/m. Nous avons particulierement etudie les noyaux situes vers les nombres de masse A 50, 90, 140 et 200. Nous comparons ensuite les valeurs experimentales de S{sub 0}, S{sub 1} et R' a differents calculs de modele optique. Un bon accord est obtenu avec un potentiel optique a absorption de surface. (auteur)

  8. Contribution to the study of solid helium-3 by nuclear magnetic resonance; Contribution a l'etude de l'helium trois solide par resonance magnetique nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Landesman, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    Due to the unusually large zero point motion of helium three atoms in the solid, the overlap of the atomic wave functions is very important. As a consequence, there are exchange interactions, the theoretical calculation and the experimental measurement of which are discussed. Nuclear magnetic resonance is especially well suited for the latter.A detailed theory is given for both exchange narrowing and Zeeman-exchange cross relaxation, which phenomena are used to measure the exchange interaction as a function of molar volume. The alignment temperature is thus known; it goes down when the pressure goes up and is never higher than three milli degrees. An influence of helium four impurities on the exchange interactions between helium three atoms which are neighbours of the substitutional He is shown. (author) [French] Par suite de l'amplitude exceptionnelle des mouvements de point zero dans l'helium trois solide, le recouvrement des fonctions d'onde atomiques est tres important. Il en resulte des interactions d' echange dont on discute l'evaluation theorique et la mise en evidence experimentale. Cette derniere peut se faire par resonance magnetique; on etudie theoriquement les phenomenes de retrecissement par echange et de relaxation Zeeman-echange que l'on met a profit pour determiner les interactions d'echange en fonction du volume molaire. On en deduit que la temperature d'alignement nucleaire diminue quand on comprime le solide et est au plus de 3x10{sup -3} K. L'influence des impuretes d'helium quatre sur les interactions d'echange entre atomes {sup 3}He voisins de {sup 4}He est mise en evidence. (auteur)

  9. Comparative study of {beta} decays and of the model of the layers for the nucleus with odd a; Etude comparee des desintegrations {beta} et du modele des couches pour les noyaux de a impair

    Energy Technology Data Exchange (ETDEWEB)

    Trocheris, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1953-07-01

    The systematic comparison of {beta} decays of the cores of number of odd mass with the predictions of the modal of Mrs. Mayer on spins and parities, has already been made by several authors. It is taken in the present work with more recent experimental data and with a method of classification of the {beta} transitions. A simultaneous comparison to the experience of the model of the layers and the theory of the {beta} transitions can serve to verify one and the other too. In the present work, it appeared more fruitful to try to verify the model of the layers with the help of the very established theory of the {beta} transitions. One will look to verify and perfect the models of the layers for transitions between fundamental states or isomers of the cores. (M.B.) [French] La comparaison systematique des desintegrations {beta} des noyaux de nombre de masse impair avec les predictions du modale de Mme MAYER sur les spins et les parites, a deja ete faite par plusieurs auteurs. Elle est reprise dans le present travail avec des donnees experimentales plus recentes et avec une methode de classification des transitions {beta}. Une comparaison simultanee a l'experience du modele des couches et de la theorie des transitions {beta} peut, a priori, servir a verifier egalement l'un et l'autre. Dans le present travail, il a paru plus fructueux de chercher a verifier le modele des couches a l'aide de la theorie bien etablie des transitions {beta}. On cherchera de verifier et de perfectionner le modele des couches pour les transitions entre etats fondamentaux ou isomeres des noyaux. (M.B.)

  10. The application of radioactive isotopes to the study of motion of silt and pebbles in the rivers and in the sea; Application des isotopes radioactifs a l'etude des mouvements des sediments et des galets dans les cours d'eau et en mer

    Energy Technology Data Exchange (ETDEWEB)

    Hours, R. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Jaffry, P. [Electricite de France (EDF), 78 - Chatou (France). Lab. National d' Hydraulique

    1959-07-01

    The application of radioactive tracers to the study of sediments drift has received considerable attention since 1954 in various countries. A comparative review is made of a number of techniques of labelling, immersing and detecting silts, sands, and pebbles. The influence of the burying of the active material is emphasized. The different experiments which have been so far carried out are described. (author) [French] L'application des traceurs radioactifs a l'etude des deplacements de sediments a fait depuis 1954 l'objet de travaux nombreux dans divers pays. On passe en revue et on compare differentes techniques de marquage, d'immersion et de detection des vases, sables et galets; on insiste sur l'influence de l'enfouissement du materiau actif. On decrit les differentes experiences effectuees jusqu'a ce jour. (auteur)

  11. Contribution to research on the metabolism of fission product. Studies on the physico-chemical state and the metabolic fate of radio-cerium solution; Contribution a l'etude du metabolisme des produits de fission. Recherches sur l'etat physico-chimique et le devenir metabolique des solutions de radiocerium

    Energy Technology Data Exchange (ETDEWEB)

    Aeberhardt, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    This paper describes a study of the physico-chemical state of radio-cerium in dilute solutions on the tracer scale, as a function of the pH of the solution. The way in which this radioelement is transported in the blood is studied in vitro and in vivo, with reference to the ionic or colloidal state of the radio-cerium used. The distribution of cerium amongst the various components of the blood is studied by a new method of blood fractionation and by paper electrophoresis. Evidence of a cerium globulin connection is shown in the case of ionic cerium. A study of the initial distribution of radio-cerium in rats, after intravenous administration of ionic or colloidal solutions, shows considerable differences according to the physico-chemical state of the cerium injected. (author) [French] Ce travail presente une etude de l'etat physico-chimique du radiocerium en solutions diluees a l'echelle des indicateurs, en fonction du pH de la solution. En fonction de l'etat ionique ou colloidal du radiocerium utilise, le mode de transport de ce radioelement dans le sang est etudie in vitro et in vivo. La distribution du cerium entre les differents constituants du sang est etudiee par une methode nouvelle de fractionnement du sang et par electrophorese sur papier. L'existence d'une liaison cerium-globuline est mise en evidence dans le cas du cerium ionique. L'etude de la distribution initiale du radiocerium, chez le rat apres administration par voie veineuse de solutions ionique ou colloidale, montre des differences importantes en fonction de l'etat physico-chimique du cerium injecte. (auteur)

  12. Effect of high energy electrons on the skin and on the underlying tissues of the rabbit. A clinical and histological study; Effets des electrons de haute energie sur la peau et les tissus sous-jacents du lapin. Etude clinique et histologique

    Energy Technology Data Exchange (ETDEWEB)

    Legeay, G.; Vialettes, H.; Adnet, J.J.; Court, L.; Masse, R. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-07-01

    The authors consider in this report the effects of high-energy electrons on rabbit teguments and on the underlying tissues after a single high dose irradiation. After briefly considering the mechanism of interaction between the electrons and matter as a function of their energy, the authors describe the dosimetry carried out, as a function of the irradiation device. The animal received surface doses of 5700 to 22100 rads in the thigh; the electron energy varied from 21 to 30 MeV. A clinical study was carried out over a period of nine months with a view to following the evolution of the damage and the functional degradation of the underlying tissues. A histological study of the induced damage was made after a second irradiation using 30 MeV electrons to produce doses of 16400 rads. Interesting observations were made concerning the damage caused to muscular and nerve tissues. (authors) [French] Les auteurs etudient, dans ce rapport, les effets des electrons de haute energie sur les teguments du lapin et les tissus sous-jacents apres une irradiation unique a dose elevee. Apres un rappel du mecanisme de l'interaction des electrons avec la matiere en fonction de leur energie, la dosimetrie realisee est exposee en fonction du dispositif d'irradiation. Les animaux ont recu, au niveau de la cuisse, des doses en surface de 5700 a 22100 rads; les energies des electrons vont de 21 a 30 MeV. Une etude clinique des lesions, observees pendant 9 mois, decrit leur evolution ainsi que les alterations fonctionnelles des tissus sous-jacents. Une etude histologique des lesions induites a ete realisee au cours d'une seconde experience pour des doses de 16400 rads avec des electrons de 30 MeV. D'interessantes observations ont ete faites concernant les lesions des tissus musculaires et nerveux. (auteurs)

  13. Etude du mecanisme de predissociation de l'ion moleculaire de protoxyde d'azote par la mesure de l'energie cinetique des fragments de l'oxyde nitrique et de l'oxygene

    Science.gov (United States)

    Delisle, Claude

    La reaction N2 + O+ ↔ NO + + N, laquelle joue un role important dans la physique de la haute atmosphere, a ete le sujet de plusieurs etudes. Bien que cette reaction ait ete l'objet d'une quantite importante de travaux, ces derniers ne permettent toutefois pas de comprendre entierement le mecanisme d'un point de vue quantique, particulierement les niveaux d'energie excites des fragments qui permettent cette reaction. Puisque cette reaction n'est pas tres facile a reproduire en laboratoire, nous avons utilise la spectroscopie laser sur faisceaux d'ions rapides afin d'explorer les limites de dissociation de l'ion moleculaire intermediaire de cette reaction, a savoir l'ion N2O+. Le faisceau d'ions N2O+ rapides, apres excitation de l'ion moleculaire vers un niveau predissocie de l'etat A2Sigma+, se dissocie pour produire les fragments ioniques O+ et NO+. Par la mesure de la variation du nombre de fragments ioniques en fonction de l'energie cinetique des ions N2O+, nous avons enregistre les spectres de predissociation de l'ion N2O+. Lorsque c'etait possible, nous avons procede a l'analyse de ces spectres de dissociation afin d'en tirer les constantes moleculaires. Pour certaines des transitions rotationnelles intenses, nous avons mesure l'energie cinetique acquise par les fragments lors de la predissociation de l'ion N 2O+. Afin d'analyser les distributions en energie cinetique, nous avons developpe une simulation de l'experience en considerant, entre autres choses, la position des niveaux de vibration et de rotation des fragments diatomiques de chacune des limites de dissociation de N2O+. Les resultats de l'analyse sont exprimes en termes de population des niveaux de vibration des fragments diatomiques pour une distribution donnee de la population des niveaux de rotation des fragments. Les resultats ainsi obtenus, montrent que les fragments diatomiques sont produits dans des niveaux de vibration fortement excites. De tels niveaux d'excitation ne correspondent pas aux

  14. Education relative a l'environnement (ERE): Une etude des representations sociales et des pratiques educatives d'enseignants de science et technologie du secondaire en contexte de formation continue

    Science.gov (United States)

    Collard-Fortin, Ugo

    Le developpement des sciences/technologie a tres clairement contribue a ce que ce dernier domaine de savoirs jouisse d'une place de choix au sein de notre societe. Au-dela des progres de notre civilisation inherents a ce dernier developpement, cette croissance amena avec elle un lot d'ineluctables dommages collateraux, contribuant en corollaire a l'emergence de diverses problematiques environnementales inquietantes pour lesquelles les valeurs ainsi que le mode de fonctionnement de la societe occidentale contemporaine sont largement tributaires. C'est entre autres en reponse a cet etat de fait que la recente vague de reforme de l'Education conduisit a l'integration, dans les curricula de sciences/technologie, de contenus relavant d'education relative a l'environnement (ERE). Face au changement, les enseignants de sciences ont du s'approprier ce nouveau programme afm de l'enseigner a leurs eleves. Toutefois, l'analyse de la situation montre que les prescriptions du programme en matiere d'ERE ne se sont pas toujours traduites en de reelles actions dans la pratique. Le contexte de notre etude s'est interesse aux pratiques educatives de l'ERE ainsi qu'a la representation sociale qui en decoule. Notre recherche aborde plus specifiquement la problematique de la modification de ces derniers objets chez les enseignants de sciences et technologie du deuxieme cycle du secondaire. Pour y arriver, nous avons propose a un groupe de trois praticiens de participer a une activite, en communaute de pratique, de formation continue orientee autour de thematiques ERE. Cette recherche developpement, s'inscrivant dans un paradigme qualitatif/interpretatif, s'est appuyee sur une cueillette de donnees effectuee a partir d'entrevues semi-dirigees, d'observations en situation et d'un groupe de discussion, au debut et a la fm de la formation continue. Les donnees brutes ont ete soumises a une demarche d'analyse inductive et ont genere diverses categories etayant nos objets de recherche

  15. Contribution to the study of fluctuations in transistors (bipolar and junction field effect types); Contribution a l'etude des fluctuations dans les transistors (bipolaires et a effet champ a jonctions)

    Energy Technology Data Exchange (ETDEWEB)

    Borel, J. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1970-07-01

    A brief review of the basic theory of fluctuations in semiconductors is given: shot, thermal low frequency noise. A measuring set has been built to draw noise spectrums (current or voltage). Noise parameters of bipolar transistors are given, mainly noise voltage. Noise current, noise factor and correlation between noise sources are also calculated. Measurements of noise parameters fit well with theory for various devices made in different technologies: alloyed, mesa, planar. Then we give results of the calculation of noise parameters in a FET starting from a simplified model of the device. Low frequency noise is taken into account. Measurements of the parameters and of the spectrum agree fairly well with the theory. Studies of low frequency noise versus temperature give the density and energy of traps located in the space charge layers and an idea of the impurity encountered in these space charge layers. [French] On rappelle les notions de base de la theorie des fluctuations dans les semiconducteurs: bruit de grenaille, bruit thermique, bruit basse frequence. Un appareillage mis au point pour tracer un spectre de bruit est decrit. On presente ensuite le calcul des parametres de bruit d'un transistor bipolaire en insistant plus particulierement sur la tension de bruit ramenee a l'entree de l'element. Le courant de bruit, le facteur de bruit et la correlation entre les sources de bruit sont calcules. La mesure des parametres de bruit est faite sur divers elements realises dans diverses technologies: alliee, mesa et plane. Les mesures confirment tres bien la theorie. On presente ensuite le calcul des parametres de bruit d'un transistor a effet de champ en definissant un schema equivalent simple de l'element. Le calcul theorique des fluctuations basse frequence est aussi fait. La mesure du spectre de bruit confirme tres bien les calculs theoriques. L'etude du bruit basse frequence en fonction de la temperature permet de remonter a la

  16. A study by internal friction of defects produced in iron and nickel irradiated at very low temperatures; Etude au moyen du frottement interne des defauts crees par irradiation a tres basse temperature dans le fer et le nickel

    Energy Technology Data Exchange (ETDEWEB)

    Keating-Hart, G. de [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    This work represents a contribution to the study of point defects in metals. After a brief review of the theory of internal friction we will discuss some technical innovations aimed at increasing the flexibility of the apparatus at our disposal. These innovations have allowed us to extend our range of measurements down to 20 deg. K. We will then discuss our experimental results. Firstly, we describe preliminary experiments on electron irradiated iron and the evidence for a laminar structure. Secondly, we present and account of the first measurements on nickel after neutron irradiation at 27 deg. K. We will compare the results with those obtained by other methods in this laboratory. Essentially we have observed transitory peaks at low temperature due to close Frenkel pairs and we have noticed the absence of a peak which would correspond to the magnetic after effect band of stage I{sub E}. An attempt is made to explain the disappearance of the observed peaks upon the application of an internal saturating magnetic field. (author) [French] Ce memoire constitue une contribution a l'etude des defauts ponctuels dans les metaux. Apres un bref apercu theorique sur le frottement interne, nous presenterons quelques realisations techniques destinees a accroitre les possibilites des instruments qui nous ont ete confies. Ces dernieres nous ont permis d'etendre la gamme des mesures jusqu'a 20 deg. K. Nous parlerons ensuite de nos resultats experimentaux. En premier lieu, ceux obtenus au cours de premieres experiences, sur le fer irradie aux electrons mettent en evidence des structures de laminage. En second lieu, nous exposerons les premieres mesures realisees sur du nickel irradie aux neutrons; nous comparerons ces resultats avec ceux obtenus par d'autres moyens experimentaux dans le laboratoire. Nous avons observe essentiellement des pics fugitifs a basse temperature dus aux paires proches de Frenckel et nous avons constate l'absence d'un pic

  17. Transfer of reactive solutes in the unsaturated zone of soils at several observation scales; Transfert de solutes reactifs dans la zone non-saturee des sols a differentes echelles d'observation

    Energy Technology Data Exchange (ETDEWEB)

    Limousin, G

    2006-10-15

    The transfer of contaminants in the unsaturated zone of soils is driven by numerous mechanisms. Field studies are sometimes difficult to set up, and so the question is raised about the reliability of laboratory measurements for describing a field situation. The nuclear power plant at Brennilis (Finistere, France) has been chosen to study the transfer of strontium, cobalt and inert tracers in the soil of this industrial site. Several observation scales have been tested (batch, stirred flow-through reactor, sieved-soil column, un-repacked or repacked soil-core lysimeter, field experiments) in order to determine, at each scale, the factors that influence the transfer of these contaminants, then to verify the adequacy between the different observation scales and their field representativeness. Regarding the soil hydrodynamic properties, the porosity, the water content in the field, the pore water velocity at the water content in the field, the saturation hydraulic conductivity and the dispersion coefficient of this embanked soil are spatially less heterogeneous than those of agricultural or non-anthropic soils. The results obtained with lysimeter and field experiments suggest that hydrodynamics of this unstructured soil can be studied on a repacked sample if the volume is high compared to the rare big-size stones. Regarding the chemical soil-contaminant interactions, cobalt and strontium isotherms are non-linear at concentration higher than 10{sup -4} mol.L{sup -1}, cobalt adsorption and desorption are fast and independent on pH. On the contrary, at concentration lower than 3.5 x 10{sup -6} mol.L{sup -1}, cobalt and strontium isotherms are linear, cobalt desorption is markedly slower than adsorption and both cobalt partition coefficient at equilibrium and its reaction kinetics are highly pH-dependent. For both elements, the results obtained with batch, stirred flow-through reactor and sieved-soil column are in adequacy. However, strontium batch adsorption measurements at equilibrium do not make possible to describe the results of field transfer experiments. (author)

  18. Contribution to the study and use of ionisation chambers for nuclear reactor control (1965); Contribution a l'etude et a l'utilisation des chambres d'ionisation pour le controle des reacteurs nucleaires (1965)

    Energy Technology Data Exchange (ETDEWEB)

    Duchene, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-02-15

    high-power reactors. (author) [French] Les chambres d'ionisation sont actuellement les detecteurs les mieux adaptes au controle des reacteurs nucleaires par des mesures neutroniques. Nous avons cru bon de rappeler quelques generalites concernant la dynamique des reacteurs, les differents procedes de detection des neutrons, le fonctionnement des chambres d'ionisation et les methodes de mesure utilisees. Notre contribution aux techniques de controle des reacteurs consiste d'une part en une tentative de synthese des facteurs intervenant dans le fonctionnement des chambres d'ionisation, l'etude de ces facteurs, et d'autre part l'elaboration de chambres d'ionisation a fission et a bore permettant de suivre la marche d'un reacteur du demarrage jusqu'a la puissance maximale. Dans le domaine des chambres a fission, nous avons en particulier ameliore les techniques de depot d'oxyde d'uranium sur l'aluminium et realise la mise au point de depots par electrolyse sur d'autres metaux: acier inoxydable, cuivre, molybdene, nickel, tantale, titane, kovar, tungstene et beryllium. Nous avons elabore plusieurs types de chambres a fission servant au demarrage des reacteurs: un type de performances moyennes actuellement utilise dans les piles francaises un type a haute sensibilite un type a haute temperature qui a fonctionne jusqu'a 600 deg. C. En ce qui concerne les chambres a bore, nous avons etudie les perturbations apportees dans les mesures par l'exposition des chambres a d'importants flux de neutrons et a un rayonnement {gamma} intense. Cette exposition produit une modification des proprietes des materiaux constitutifs et la production dans les chambres d'un bruit de fond qui peut gener considerablement les mesures neutroniques. Nous avons montre que la technique de compensation permettait de limiter l'importance de ce bruit de fond et d'augmenter ainsi la plage de fonctionnement des

  19. Development of a method for studying non-linear phenomena in plasma; Mise au point d'une methode d'etude des phenomenes non lineaires dans un plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gonfalone, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1965-03-01

    The study of non-linear phenomena resulting from the interaction of powerful electro-magnetic waves with an electron gas is the basis of the p best methods for measuring the frequency of electronic collisions in the ionosphere. In laboratory plasma the appearance of these phenomena is connected with a powerful critical field. Although we have used a relatively low-power electromagnetic source, we have been able to develop a simple hyper-frequency method making it possible to study these phenomena to measure them and to put forward an elementary interpretation. An electromagnetic wave provided by a 1 watt klystron interacts with a HF discharge (25 MHz) in the volume of a TE{sub 111} cavity. The tube containing the discharge and the axis of the cylindrical cavity are co-linear with a magnetic field which can attain a value such that the wave frequency is equal to the gyromagnetic frequency of the electrons. The resonance curve for the cavity, which depends on the electronic density and the frequency of collisions, becomes increasingly dissymmetric as the absorbed power increases and as the gyromagnetic frequency of the electrons approaches that of the incident wave. By studying the resonance, it is possible to calculate the proportionality coefficients relating the density and collision frequency variations with the absorbed power. The experiments were carried out by causing the following to vary separately: the incident UHF power, the initial electronic density, the pressure of the neutral ambient gas, and the axial magnetic field. The variation in the electronic density as a function of the magnetic field for a high UHF power shows a resonance of dissymmetrical form, sometimes with a sharp peak in the neighbourhood of {omega}{sub H}. The possibility of applying these properties to the construction of practical devices, is under consideration. (author) [French] L'etude des phenomenes non lineaires dus a l'interaction d'ondes electro

  20. Tunnel diode amplifiers and their background noise as a function of the polarization point, the temperature, and the bandwidth; Amplificateurs a diode tunnel et leur bruit de fond, en fonction du point de polarisation, de la temperature et de la bande passante

    Energy Technology Data Exchange (ETDEWEB)

    Ozveaminian, K. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    The author presents mathematical and graphical methods for the study of the stability of tunnel diode circuits. He gives an application to the realization of three amplifiers. Then he describes a theoretical and experimental investigation of the noise of these amplifiers and of its variations with the bias, the temperature and the bandwidth. (author) [French] L'auteur presente deux methodes, l'une theorique l'autre graphique, pour l'etude de la stabilite des circuits a diode tunnel, dont il fait une application a la realisation de trois amplificateurs. Il effectue ensuite une etude theorique et experimentale du bruit de fond de ces amplificateurs, en fonction du point de polarisation, de la temperature et de la bande passante. (auteur)

  1. Interferometric methods for the characterization of photosensitive and nonlinear optical materials

    Science.gov (United States)

    Yavrian, Artashes

    Dans cette these nous presentons d'abord nos etudes des proprietes photoinduites dans les polymeres dopes avec colorant azoique. Nous avons demontre experimentalement que l'onde optique polarisee circulairement induit aussi bien un axe d'anisotropie dans ces materiaux que l'onde polarisee lineairement. Les processus a deux couleurs ont ete etudies et utilises pour l'amelioration significative de la qualite d'une image enregistree holographiquement dans ces polymeres. Les coefficients non lineaires de l'indice de refraction et d'absorption des echantillons frais et vieillis ont ete mesures en utilisant la technique de z-scan. Le role du vieillissement de la matrice polymerique durant ces mesures a ete etudie. Nous avons aussi propose et realise experimentalement une nouvelle technique interferometrique-ayant-une excellente-stabilite-mecanique. La non-linearite optique des polymeres dopes avec les colorants azoique et des crystaux liquides a ete mesuree avec cet interferometre.

  2. Thermal and hydrodynamic study of a whirling liquid hydrogen layer under high heat flux; Etude thermique et hydrodynamique d'une couche tourbillonnaire d'hydrogenen liquide sous flux de chaleur eleve

    Energy Technology Data Exchange (ETDEWEB)

    Ewald, R. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1968-03-01

    In order to achieve a cold neutrons source ({lambda} {>=} 4.10{sup -10} m) in a high flux reactor ({approx} 10{sup 15} neutrons/cm{sup 2}.s), a whirling liquid hydrogen layer (145 mm OD, effective thickness 15 mm, height about 180 mm) was formed, out-of-pile, in a cylindrical transparent glass vessel. The whirling motion was obtained by tangential injection of the liquid, near the wall. Thermal and hydrodynamical conditions of formation and laws of similarity of such a layer were studied. The characteristics of this whirling flow were observed as a function of mass flow rate (5 to 27 g/s; 4.3 to 23 l/mn), and of spillway width (18 and 25 mm). Six different nozzles were used : 1.0; 1.5; 1.9; 2.25; 2.65 and 3.0 mm ID. The total heat influx was found between 8.6 and 10.4 kW. The heat flux density was about 9.4 W/cm{sup 2} and the mean layer density around 80 per cent of that of the liquid hydrogen at 20.4 Kelvin. High speed movies were used to analyze the boiling regime. (author) [French] En vue de realiser une source de neutrons froids ({lambda} {>=} 4.10{sup -10} m) dans un reacteur a haut flux ({approx} 10{sup 15} neutrons thermiques/cm{sup 2}.s), on a forme dans un vase cylindrique transparent en verre, hors-pile, une couche tourbillonnaire ('vortex') d'hydrogene liquide (diametre exterieur 145 mm, epaisseur effective 15 mm, hauteur 180 mm environ). Le mouvement giratoire est obtenu par injection tangentielle du liquide pres de la paroi. L'etude porte sur la determination des conditions thermiques et hydrodynamiques de la formation d'une telle couche et sur les regles de similitude de ce phenomene. On a observe les caracteristiques de l'ecoulement giratoire en fonction du debit (de 5 a 27 g/s, soit de 4.3 a 23 1/mn), de la vitesse d'injection (entre 10 et 110 m/s) et de la largeur du deversoir (18 et 25 mm), ceci pour six diametres differents d'injecteur (1.0 ; 1.5; 1.9; 2.25; 2.65 et 3.0 mm). Le flux de chaleur total mesure

  3. The use of tracers in the study of the ionic permeability of the nerve; Utilisation des indicateurs nucleaires dans l'etude de la permeabilite ionique du nerf

    Energy Technology Data Exchange (ETDEWEB)

    Guinnebault, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    The use of the radioactive tracers {sup 24}Na and {sup 42}K, and the electrophysiological fine study carried out on the plant Cephalopods nervous cells have made it possible, during ten years, to study the relationships between the electrical phenomena observed during the propagation of the nervous impulse and the ionic movements which occur at the cell membrane between the intra- and extra-cellular media. In the state of rest, the nerve fibres present a certain permeability towards sodium and potassium, a permeability which allows the renewal, from the extra-cellular medium, of the cations contained in the cytoplasm. At the moment of the passage of the nervous impulse, it is possible to demonstrate a temporary increase in the permeability towards the sodium which causes the entry of Na{sup +} ions into the nerve fibre, whilst, a few milliseconds later, the increase in the potassium permeability causes the departure of an equivalent quantity of K{sup +} ions. A recovery phase follows the passage of the nervous impulse, during which the original ionic conditions are re-established. If the potassium movements can be considered as passive, the expulsion of Na{sup +} requires, on the part of the cell, the use of a part of the metabolic energy. (author) [French] L'utilisation des indicateurs radioactifs {sup 24}Na et {sup 42}K, et l'etude electrophysiologique fine realisee sur des cellules nerveuses geantes de Cephalopodes a permis, depuis une dizaine d'annees, d'etudier les rapports entre les phenomenes electriques observes lors de la propagation de l'influx nerveux et les mouvements ioniques qui s'effectuent au niveau de la membrane cellulaire entre milieux intracellulaire et extracellulaire. A l'etat de repos, les fibres nerveuses possedent pour le sodium et le potassium, une permeabilite qui permet le renouvellement, a partir du milieu extracellulaire des cations contenus dans le cytoplasme. Au moment du passage de l

  4. Fragmentation study of isolated and nano-solvated biomolecules induced by collision with multiply charged ions and neutral particles; Etude de la fragmentation de molecules d'interet biologique isolees et nano-solvatees induite par collision avec des ions multicharges et des particules neutres

    Energy Technology Data Exchange (ETDEWEB)

    Bernigaud, V.

    2009-08-27

    This thesis concerns a gas phase study of the fragmentation of bio-molecular systems induced by slow collisions with multiply charged ions (in the keV-region), alkali atoms and rare gases. The main objective was to study the physical processes involved in the dissociation of highly electronically excited systems. In order to elucidate the intrinsic properties of certain biomolecules (porphyrins and amino acids) we have performed experiments in the gas phase with isolated systems. The obtained results demonstrate the high stability of porphyrins after electron removal and attachment. Furthermore, a dependence of the fragmentation pattern produced by multiply charged ions on the isomeric structure of the alanine molecule has been shown. In a second part of the thesis, a strong influence of the environment of the biomolecule on the fragmentation channels, their modification and their new opening, has been clearly proven. This phenomenon occurs in the presence of other surrounding biomolecules (clusters of nucleobases) as well as for molecules of a solvent (molecules of water, methanol and acetonitrile) in which the biomolecule is embedded. In order to extend these studies to larger systems, a new experimental set-up, based on an electro-spray ion source combined with a quadrupole mass filter has been developed. Due to the successful tests and proposed improvements of the device future experiments will become available concerning the fragmentation of large charged and solvated bio-molecular systems induced by collision processes. (author) [French] Cette these est une etude de la fragmentation en phase gazeuse de molecules d'interet biologique soumises a des collisions avec des ions multicharges de basse energie (energie cinetique de quelques keV) et des atomes alcalins ou de gaz rare. L'objectif est d'etudier les processus physique qui conduisent a la dissociation de ces systemes soumis a une excitation electronique intense. Afin de mettre en evidence

  5. A study of the fluorescence of the rare gases excited by nuclear particles. Use of the principle for the detection of nuclear radiation by scintillation; Etude de la fluorescence des gaz rares excites par des particules nucleaires. Utilisation pour la detection des rayonnements nucleaires par scintillation

    Energy Technology Data Exchange (ETDEWEB)

    Koch, L. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1959-12-15

    In the first part is studied the properties of atoms excited by the passage of {alpha} particles through the various rare gases at atmospheric pressure. A spectral analysis of the emitted light showed that certain impurities play an important part in producing the fluorescence, and it has led to the conclusion that the light emission contains at least two components - one very short - lived due to the direct deexcitation of the rare gas, the other relatively slower due to the energy transfers to the impurity. The measurement of the life-time of the excited states has confirmed this foregoing hypothesis, the rapid part of the impulse is extremely short: less than 2,25.10{sup -9} s in the case of xenon; the slower part has a life-time depending directly on the nitrogen concentration, nitrogen being the impurity giving the largest effect in all cases. The study of rare gases under the influence of an electric field has made it possible to show that the amount of light produced by an {alpha} particle can be multiplied (by 60, for example, in a field of 600 V:cm) so that the luminescent efficiency is greater than in the case of INaTI. In the second part the characteristics of the rare gases acting as scintillators is examined, the most important property being the absence of fluorescence saturation when the intensity of the excitation incident on the gas is very large. This, together with the very short time of scintillation has made it possible to study a certain number of nuclear physical applications (heavy particle energy-measurements, kinetic studies on nuclear reactors, neutron spectroscopy). (author) [French] On etudie dans la premiere partie les proprietes des atomes excites par le passage de particules {alpha} dans les differents gaz rares a la pression atmospherique. L'etude spectrale de la lumiere emise a montre que certaines impuretes jouent un role considerable dans la fluorescence et on a ete amene a penser que l'emission de lumiere comporte au

  6. A study of internal contamination levels resulting from {sup 90}Sr and {sup 137}Cs environmental pollution. The influence of different factors; Etude des niveaux de contamination interne resultant d'une pollution de l'environnement par le {sup 90}Sr et le {sup 137}Cs influence des differents parametres

    Energy Technology Data Exchange (ETDEWEB)

    Garnier, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1970-07-01

    This study includes two parts. The purpose of the former one is to try and evaluate the amounts of {sup 90}Sr and {sup 137}Cs dietary intakes as a function of age with a view to assessing internal exposure doses and estimating the critical age, and to study the relative significance of the several factors it depends on. The data used are both the results of dietary surveys made in 11 districts of the European community from which the evolution of the consumed amounts of 13 groups of foodstuffs, as a function of age was derived, and the mean factors of contamination pathways. The variability of some factors is very large and an attempt is made to assess their significance on the whole contamination; also, the influence of the various diets has been emphasized. The purpose of the second part is to assess, doses as a function of age in the case of protracted exposure on the basis of the aforesaid results and radiobiological factors derived from bibliographic states of the arts. An assessment is made of body burdens and mean doses (either to the skeleton or the whole body according to the radionuclides) originating either from a direct unitary exposure or from situations implying both modes of exposure. As assumed only the diets vary with the districts, thus the results reflect their significance which should be corrected, for a more accurate assessment of the dose variability, by the significance of human and transfer factors. (author) [French] Cette etude comprend deux parties. L'objet de la premiere partie est a la fois un essai d'evaluation en fonction de l'age des quantites de strontium 90 et de cesium 137 ingerees avec les aliments dans la perspective d'une application a l'estimation des doses d'irradiation interne et a la recherche de l'age critique, et une etude de l'influence relative des divers parametres dont elle depend. Les donnees utilisees sont, d'une part, les resultats des enquetes alimentaires faites en

  7. Peculiaridades de la investigación científca en áreas experimentales y no experimentales. Repercusiones en los modelos de evaluación

    OpenAIRE

    López Baena, Alfonso Juan

    2005-01-01

    The relative importance of inputs and outputs from the point of view of the researchers is shown. Differences detected between areas are also described. A quality assessment of journals in seven scientific fields (Law, Economics, Art & History, Social Sciences, Philology, Philosophy, Educational Sciences and Psychology) is described. The system developed has been used in several institutional assessment of R&D activities. Se muestra la importancia que los científicos de los distintos campo...

  8. Nouvelles: KEK: B pour BELLE; NA48 mesure la violation directe de CP; LEL: le laser à électrons libres dépasse le kilowatt; Le LEP à 100 pour 100; Tour d'honneur au RHIC; Mesures de précision; Etude sur les modes de gestion du village planétaire; Conférence PANIC99 à Uppsala; Rencontre électron-noyau à HERA; LPP, Doubna célèbre une décennie; Les physiciens auscultent le photon; Aimants chauds venus du froid

    CERN Multimedia

    1999-01-01

    Nouvelles: KEK: B pour BELLE; NA48 mesure la violation directe de CP; LEL: le laser à électrons libres dépasse le kilowatt; Le LEP à 100 pour 100; Tour d'honneur au RHIC; Mesures de précision; Etude sur les modes de gestion du village planétaire; Conférence PANIC99 à Uppsala; Rencontre électron-noyau à HERA; LPP, Doubna célèbre une décennie; Les physiciens auscultent le photon; Aimants chauds venus du froid

  9. Radiobiological study of the radioprotective activity of a natural Iranian compound, ''Shir-Khecht''; Etude radiobiologique de l'activite radioprotectrice d'un compose naturel Iranien: le ''Shir-Khecht''

    Energy Technology Data Exchange (ETDEWEB)

    Rouhanizadeh, N. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-01-01

    After reviewing the primary mechanisms of the action of ionizing radiation, the possible mechanisms of the action of radioprotective substances, the various chemical structures having a protective effect and the methods for studying chemical radioprotection, the author presents the results he has obtained with natural Iranian product: ''Shir-Khecht''. Tests with this product at lethal and sublethal doses have been carried out on the rat using various means of introduction. The effect of radiation, both with and without protection, has been studied using histological and biochemical methods. The product examined has, in effect, a protective action; it is, furthermore, non-toxic and active when taken orally. (author) [French] Apres avoir rappele les mecanismes primaires de l'action des rayonnements ionisants, les mecanismes possibles de l'action des substances radioprotectrices, les diverses structures chimiques possedant un effet protecteur et les methodes d'etude de la radioprotection chimique, l'auteur presente les resultats qu'il a obtenus en utilisant un compose naturel iranien: le ''Shir-Khecht''. Des essais de ce produit, chez le rat, par diverses voies d'introduction, a dose letale et subletale ont ete effectues. L'effet des radiations, avec et sans protection, a ete etudie a l'aide de methodes histologiques et biochimiques. Le compose essaye possede un pouvoir protecteur; il est, de plus, non toxique et actif par voie orale. (auteur)

  10. Electron spin resonance and E.N.D.O.R. double resonance study of free radicals produced by gamma irradiation of imidazole single crystals; Etude par resonance paramagnetique electronique et double resonance E.N.D.O.R. des radicaux libres crees par irradiation gamma de monocristaux d'imidazole

    Energy Technology Data Exchange (ETDEWEB)

    Lamotte, B. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1970-07-01

    Gamma irradiation of imidazole single crystals at 300 deg. K gives two radicals. Identification and detailed studies of their electronic and geometric structure have been made by ESR and ENDOR techniques. A study of the hydrogen bonded protons hyperfine tensor is made and let us conclude to the inexistence of movement and tunneling of these protons. The principal low temperature radical, produced by gamma irradiation at 77 deg. K has been also studied by ESR and a model has been proposed. (author) [French] L'irradiation gamma de monocristaux d'imidazole a 300 deg. K conduit a deux radicaux dont l'identification et l'etude detaillee des structures electroniques et geometriques ont ete obtenues par la resonance paramagnetique electronique (RPE) et la double resonance ENDOR. En particulier l'examen des protons de la liaison hydrogene permet de conclure, pour ceux-ci, a l'inexistence de tout mouvement par effet tunnel. De plus, l'analyse des spectres de RPE du radical principal cree par irradiation gamma de l'imidazole a 77 deg. K nous a permis de proposer un modele pour ce radical. (auteur)

  11. HBA1c: clinical and biological agreement for standardization of assay methods. Report by the experts of ALFEDIAM (Association de Langue Française pour lEtude du Diabète et des Maladies Métabolique) and SFBC (Société Française de Biologie Clinique).

    Science.gov (United States)

    Gillery, P; Bordas-Fonfrède, M; Chapelle, J P; Drouin, P; Hue, G; Lévy-Marchal, C; Périer, C; Sélam, J L; Slama, G; Thivolet, C; Vialettes, B

    1999-09-01

    Glycohaemoglobin, and particularly haemoglobin A1c(HbA1c), assays have been used for many years to retrospectively evaluate the glycaemic control of diabetic patients. Cut-off values have been established for deciding treatment modifications. The techniques used in the laboratories however exhibit varying quality, and all of them are not yet standardized. The consequence is an under-utilization of this test, especially in non-hospital practice. In this context, working groups of Société Française de Biologie Clinique (SFBC), Association de Langue Française pour l'Etude du Diabète et des Maladies Métaboliques (ALFEDIAM) and Société Française d'Endocrinologie (SFE) have met together, in order to analyze the national status, and to propose practical recommendations for implementing a standardization process on the basis of international experiences. It is recommended to exclusively express results as HbA1c percentage, using methods standardized and certified by comparison to reference methods such as those using Diabetes Control and Complications Trial (DCCT) values. Simultaneously, contacts have been established with manufacturers, and the realisation of periodic quality control surveys was encouraged.

  12. Histological data concerning the pig (sus scrofa) for use in radiobiology. I. Normal histology of certain systems. 2. Injuries caused by total {gamma} irradiation; Donnees histologiques sur le porc (sus scrofa), utilisables en radiobiologie. 1. histologie normale de certains appareils. 2. etude des lesions consecutives a une irradiation {gamma} totale

    Energy Technology Data Exchange (ETDEWEB)

    Guenet, J.L.; Vaiman, M.; Nizza, P. [Commissariat a L' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1966-06-01

    The domestic pig lately become a laboratory whose anatomical and physiological characteristics appear to be appreciated for certain radiological studies. In this report the authors describe research which they have carried out (in particular in the field of histology) on domestic pigs of different species with a view to compiling a record which might be of help to future workers in this field. The second part of their work deals with anatomical and histological injuries caused by total exposure to gamma radiation from cobalt 60 at doses of around 285 rads. (authors) [French] Le porc domestique est devenu depuis peu un animal de laboratoire, dont les caracteristiques anatomiques et physiologiques paraissent fort appreciees pour certaines etudes de radiobiologie. Dans ce rapport les auteurs font part des recherches qu'ils ont effectuees (notamment dans le domaine de l'histologie) sur des porcs domestiques de differentes races, de maniere a constituer un document capable de venir en aide aux utilisateurs eventuels. La deuxieme partie de leur travail traite de lesions anatomiques et histologiques, consecutives a des expositions totales aux rayonnements gamma du cobalt 60 a des doses voisines de 285 rads. (auteurs)

  13. Etude de la mesure du paramètre alpha dans le cadre de la violation de la symétrie CP à l'aide du canal $B_{d}^{0} \\to \\pi^{+} \\pi^{-}\\pi^{0}$ dans l'expérience LHCb

    CERN Document Server

    Robert, Arnaud

    2005-01-01

    L'analyse temporelle du correlogramme de Dalitz du canal a trois corps Bd en pi+ pi- pi0 conduit a l'extraction de l'un des parametres definissant la violation de la symetrie CP dans le Modele Standard Electrofaible, l'angle alpha, exempte d'ambiguites discretes entre 0 et pi. Elle permet, entre autres, d'acceder independamment aux valeurs des principaux parametres QCD regissant la desintegration. La contrepartie experimentale repose cependant sur une statistique de signal suffisamment pure et importante et une maitrise precise de la phenomenologie associee. Combines a un rapport d'embranchement de l'ordre de 2.10^{-5}, ces deux arguments justifient a eux seuls le caractere non trivial d'une telle analyse dans l'environnement hadronique de l'experience dediee LHCb. A partir de la reponse simulee du detecteur, et en particulier des performances du calorimetre electromagnetique, cette these montre l'interet essentiel de la reconstruction specifique des pions neutres tres energiques et la necessite d'introduire ...

  14. Study of cis- and trans-uranium elements by paper chromatography and electrophoresis; Contribution a l'etude des elements cis- et trans-uraniens par chromatographie sur papier et electrophorese

    Energy Technology Data Exchange (ETDEWEB)

    Clanet, F. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-01-01

    In this work, the field of application of paper chromatography and electrophoresis in inorganic chemistry has been extended to elements 90 to 96 in hydrochloric and nitric acid solution. Results obtained concern the following points: 1) - Characterization of the valency states of Np and of Pu using coloured reactions on chromatograms and electrophoregrams. The valency IV is characterized by alizarin, arsenazo-I and thorin-I, whilst diphenylcarbazide is used for the hexavalent state. 2) - Paper chromatography: by using as eluent, mixtures of equal parts of aqueous HCl and HNO{sub 3} solutions and of alcohols (methanol, ethanol and n-butanol), the R{sub f} values of elements 90 to 96 have been determined. It has been possible to deduce certain conclusions concerning the complexing of these elements by Cl{sup -} and NO{sub 3}{sup -} ions. 3) - We have developed an electrophoretic technique on cellulose acetate membranes in order to separate the charged species formed by the elements 90 to 96 in HCl and HNO{sub 3} solutions from 1 to 12 M. Mobility curves have been obtained. It appears from our results that the tendency for the elements considered to form anionic complexes follows the order of the ionic potentials when the valency state is four; this order is reversed for the valency three. The ions Cl{sup -} have a smaller tendency to form complexes than the NO{sub 3}{sup -} ions with respect to these elements in their oxidation state III or IV, but the reverse phenomenon is observed for U{sup VI} and Pu{sup VI}. Finally, the complexing of the cations Pu{sup 4+} and PuUO{sub 2}{sup 2+} by NO{sub 3}{sup -} follows the order of the ionic potentials but occurs in the reverse order for Cl{sup -} ions. 4) - Various analytical applications are considered: separation of the various elements from each other and separation of the valency states of Np and of Pu. (author) [French] Dans cette etude, le champ d'application de la chromatographie sur papier et de l

  15. etudes ethnomycologiques et identification des champignons ...

    African Journals Online (AJOL)

    Les connaissances endogènes sur les champignons comestibles sont peu documentées en Afrique de l'Ouest. La présente étude vise à identifier les champignons sauvages les plus consommés dans la région des Monts-Kouffè au Bénin. Cette étude réalisée de juillet à août 2014, a d'abord consisté en une enquête.

  16. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Ces changements climatiques menacent également et directement la vie humaine. En effet, en été 2003 en. Europe, le réchauffement climatique a provoqué la mort de près de 30000 personnes dont 14082 en France,. 7000 en Allemagne, 4000 en Italie et 2045 en Grande Bretagne [3]. C'est dans ce contexte que depuis.

  17. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    (2002) Caractéristiques microstructurales et propriétés relatives à la durabilité des bétons. Méthodes d'essai N°58 ; LCPC ; 1er trimestre 2002. [8] - A. Turatsinze, F. Hussein and J. L. Granju. (2000) Durability of metal-fibre reinforced concrete repairs: drying shrinkage effects. Proceeding of the Sixth International Symposium ...

  18. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Ibn Batouta, B.P. 703 Agdal, Rabat. 5Laboratoire de Microbiologie Appliquée. Laboratoire de Biologie et Santé, Faculté des Sciences, Kénitra. 6Laboratoire Environnement & Energies Renouvelables, Equipe: Environnement, Patrimoine & Santé ; Faculté des Sciences, Université Ibn Tofail, B.P. 133, 14000 Kénitra, Maroc ...

  19. Etude dendrometrique de Pterocarpus erinaceus poir. des ...

    African Journals Online (AJOL)

    Pterocarpus erinaceus is an arborescent deciduous legume tree of African savannas and dry forests growing in natural stands in the sudanian zone in Benin. An inventory of trees in the P. erinaceus dominated communities was carried out in order to describe their structure in tree-savannah and woodland, on the basis of ...

  20. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Les sols ferrallitiques fortement désaturés sont appauvris et sont formés sur matériaux sableux ou sablo-faiblement argileux, ... Pétri garnies du papier buvard imbibé d'eau. A partir du premier jour après la ... Son léger raccourcissement à trois mois peut s'expliquer par sénescence qui provoque la chute d'une portion de ...

  1. etudes ethnomycologiques et identification des champignons ...

    African Journals Online (AJOL)

    Crisan E. V. and A. Sands. 1978. Nutritional value. In The Biology and Cultivation of Edible. Mushrooms (ed. S. T. Chang & W. A. Hayes). Academic Press : New York : 137-168. De Kesel A. 2001. A mushrooms dryer for the travelling mycologist. Field Mycol. 2 (4) : 131-133. De Kesel A., Codjia J.C. and S.N. Yorou. 2002.

  2. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Résumé. L'avifaune de la forêt classée de N'ganda N'ganda (FCNN), un des sites Ramsar de Côte d'Ivoire, est méconnue. De mai 2003 à novembre 2005, des inventaires avifauniques effectués dans cette forêt ont permis d'identifier 132 espèces reparties en 44 familles. La famille des Nectariniidae est la mieux.

  3. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    ces formations, la nature des phases minérales, les différentes phases de métamorphisme ayant affecté les corps minéralisés et les roches encaissantes, ainsi qu'une mise en évidence des différentes paragenèses entrant dans la composition des corps minéralisés [2,3]. Dans cette note, nous proposons la discussion de.

  4. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Les paramètres du sol sur le bilan de salure sur extrait de pat saturée ont été effectuées dans les laboratoires de biologie et ... *Carbone Org (%). *Matière Org (%). 5.84. 10.04. 04.91. 09.52. 03.84. 06.60. 02.69. 04.62. 06.76. 11.63. 05.68. 09.78. *Na+(ppm). * K+(ppm). 316.23. 4.2. 55.35. 04.20. 173.97. 07.20. 220.57. 04.50.

  5. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    La population de Taza, estimée à environ 154 496 habitants, produit 18 000 tonnes par jour de déchet solide et ceci malgré la ... Mots-clés: décharge sauvage, lixiviats, pollution, physico-chimie, Taza. Abstract ... pérenne des déchets solides et des rejets liquides qui sont aboutissent dans le milieu récepteur aquatique.

  6. CLINICAL STUDIES/ETUDE CLINIQUES COMPARISON OF ...

    African Journals Online (AJOL)

    To assess the manifestations of pain in PD (Parkinson's disease ) patients versus .... of body affected, Hoehn and Yahr stage, UPDRS score, etc. ..... The Unified Parkinson's Disease Rating Scale (UPDRS): status and recommendations.

  7. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    estimation de la densité spectrale de puissance P(f) du processus x(nTe) est biaisé. Lorsque N tend vers l'infini ce filtre tend vers δ(f), le périodogramme est donc asymptotiquement sans biais. 2-3-2. Variance. La moyenne est un critère de ...

  8. ETUDE COMPAREE DES COMPLICATIONS DES AVORTEMENTS ...

    African Journals Online (AJOL)

    Ndombi I, Mendome G. Audit des décès maternels au Centre Hospitalier de Libreville (2005 à 2007). Journal de la SAGO 2007; 8 :29-33. 14.Guillaume A, William M. L'avortement provoqué en. Afrique : un problème mal connu, lourd de conséquences.LaboratoirePopulation-. Environnement-Développement. Unité mixte de.

  9. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    En effet, de nombreux modèles climatiques prévoient que le changement climatique aura des répercussions négatives sur ... paysans enquêtés considèrent la baisse de la fertilité des sols comme principal effet néfaste des changements climatiques sur ...... Englewood Cliffs, NJ: Prentice Hall. (1991). [29] - R. P, NEUPANE, ...

  10. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    L'agarophyte Gelidium sesquipedale est une rhodophycée très commune sur les côtes marocaines, son exploitation et sa transformation locale ont précédé toute étude scientifique. L'étude de la croissance de cette espèce en milieu naturel a montré que son rythme d'élongation est faible avoisinant 9cm par an.

  11. Etude Sedimentologique et Esquisse Paleoenvironnementale des ...

    African Journals Online (AJOL)

    sédimentation, présentant des faciès de type sigmoïde, s'est faite par accumulation libre, par saltation et par suspension. Les grains de quartz .... débris de fossiles (radioles d'échinodermes, débris de mollusques, de bryozoaires et d' ... l'énergie de l'agent de transport (Pinot, 1994), et suggère une sédimentation réalisée ...

  12. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Ben Mohammed a été axée principalement sur la recherche de données géologiques et gîtologiques dans le but de dégager tous les .... Phases minérales : Mt: Magnétite ; Hem: Hématite ; Sid: Sidérite ; Fa : Fayalite ;. Hed : Hédenbergite; Q : Quartz, Chert ; Cc : Calcite. Mc. M i. M s . Fay . Hed. Ca (Cc). Si (Q, Chert). Fe (Mt ...

  13. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Impact des lixiviats de la décharge sauvage de la ville de Taza sur les ressources hydriques (Maroc) ... 1. Introduction. L'avenir des ressources en eau de la ville de Taza est fortement conditionné par la gestion rationnelle et ... Étant donnée, que la décharge ne possède ni des installations techniques pour la protection de.

  14. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Car, malgré la maîtrise des techniques culturales, les productions fluctuent d'une année à l'autre [7]. Malgré les efforts consentis, les agro-industries enregistrent toujours des fluctuations des rendements. C'est dans cette optique que de nombreux auteurs [8,9] présentent le climat comme étant un facteur limitant de premier ...

  15. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    l'étude de nombreux paramètres (concentration, température, l'ajout de la bentonite), nous avons démontré que les boues ... haute densité (PEHD) et des matériaux argileux spécifiques de type bentonite. A ce jour ..... [4] - K. VERBURG AND P. BAVEYE “Hysteresis in the binary exchange of cations on 2:1 clay minerals : a.

  16. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    d'apodisation Boxcar, Bartlett, Blackman, Hamming, Hanning, Kaiser et Chebyshev, de durée 0.2557 (segment de 1024 points). L'étude comparative sera axée sur les valeurs d'amplitude de chacun des pics pour les deux variantes du périodogramme. Nous regroupons alors les résultats des simulations sur le Tableau 2.

  17. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Haute –Volta) »,. Changements Globaux en Afrique durant le Quaternaire. Symposium. INQUA-ASEQUA, ORSTOM, Paris (1986) pp 221 -225. [21] - E. HIEN, F. GANRY, V. HIEN et R. OLIVIER, « Dynamique du carbone dans un sol de savane du sud –ouest Burkina sous l'effet de la mise en culture des pratiques culturales ...

  18. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    significativement avec le pourcentage de semences contaminées par les Fusarium (– 0,93) et par les. Aspergillus (– 0,72). Les pourcentages de germination et de contamination par les différents champignons sont très variables selon les génotypes des pieds-mères. Les semences de l'année conservées au froid dès.

  19. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    1. ISSN 1813-548X, http://www.afriquescience.info. Erramli HAMID et al. Étude de la dégradation d'une canalisation de conduite d'eau en béton armé. Erramli HAMID, Dermaj AHMED*, Driss CHEBABE, Moustafa DOUBI, Najjat HAJJAJI et Srhiri ABDELLAH. Laboratoire d'Electrochimie, Matériaux et Environnement, Faculté ...

  20. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    côtés digitalisés à partir de la carte topographique. Ce travail est complété par un traitement statistique et géostatistique. Ainsi une analyse multidimensionnelle utilisant l'analyse en composante principale (ACP) a permis de déterminer les principaux axes factoriels. Le traitement géostatistique des données géochimiques a ...

  1. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    1991) 400 pp. [15] - P. Ondina, « Gasteropodos terrestres de A Coruna y Pontevedra ». Tesis Doctoral. Universitat De Santiago. (1988) 386 p. [16] - A. Martinez - Orti, « Moluscos terrestres testaceos de la comunidad Valenciana ». Tesis Doctoral ...

  2. Etude acoustique du systeme vocalique du chichewa

    African Journals Online (AJOL)

    le yao (10 %), le tumbuka (6,4 %), le nyakyusa-ngonde (2,9 %), le sena. (2,4 %) et le tonga (2, 1 %). Les langues pratiquees par ces .... Tisfyeni tip(1te kwambfri. Laissez-les beaucoup provoquer. Le deuxieme ..... rencontrer Jes cinq phonemes du chichewa : /a e i o ul. Rappelons que Jes elements stables de la phrase ...

  3. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    cru, bouilli ou frit dans plusieurs régions du monde (Afrique, Jamaïque, Haïti) [1]. Sa richesse en huile. (45,5%) [2] impose qu'on y accorde une attention particulière. D'ailleurs, elle contribue de façon importante à l'alimentation de nombreux jamaïcains [3]. En Côte d'Ivoire, peu de travaux ont porté sur cette huile. Les.

  4. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    A la fin de l'expérimentation, le sang des rats est prélevé, après anesthésie, au niveau du sinus orbital de l'œil à l'aide de pipettes pasteurs. Le sang de chaque ..... caractérisation moléculaire devrait être entreprise pour connaître les molécules constitutives de cette huile. Références. [1] - M. ARBONNIER « Arbres, arbustes ...

  5. Etude Differentielle Intonative Francais/Anglais.

    Science.gov (United States)

    Lepetit, D.; Martin, Ph.

    1990-01-01

    Describes an investigation of the differences and similarities existing between the intonation systems of French and English. The unity of the procedures described here is confirmed by an analysis of intonational errors made by English-speaking learners of French. (Author/VWL)

  6. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    d'hydrogène et les composés organiques. A pH proche de la neutralité, il a été démontré que la décomposition de H2O2 par Fe(II) ne conduit pas directement à la production des radicaux hydroxyles, mais à la formation d'un intermédiaire qui peut libérer des radicaux hydroxyles et Fe(III) selon la réaction suivante [8] : ( ).

  7. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    anomalies are linked to the zonal wind anomalies and the increased in the rainfall is associated with the large modulations of the African Easterly jet (AEJ). The two positive rainfall anomalies maxima are located near Guinea and Chad coinciding with two maxima of the composite zonal water vapor flux anomalies in the.

  8. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    sols non protégés à des phénomènes violents (pluies orageuses, érosion éolienne et hydrique). Ceci compromet le potentiel des pratiques actuelles de gestion des terres à maintenir les ressources naturelles, contribuant ainsi au déboisement, à l'érosion des sols, à leurs appauvrissement en matières organiques et à.

  9. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    anastomosés. La caractérisation pétro-sédimentologique révèle la présence de certains minéraux tels que : quartz, hématite, biotite, sillimanite, scheelite, goethite, limonite, manganèse, pyroxène et tourmaline. Les grès auraient un ciment hémato-manganeux. Aussi, les sables sont moyennement classés. Ces sables ont.

  10. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    des carbonates (calcite et dolomite) et le quartz en utilisant la spectroscopie IR et la spectrométrie à gamme visible. Les acides gras fractions C10-C16 jouent le rôle de collecteurs anioniques dans la flottation des carbonates alors que le triazine est utilisé comme collecteur cationique pour flotter le quartz. Le concentré de ...

  11. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Les effets d'irrigation par l'eau salée sur les propriétés physico-chimiques d'un sol planté avec Atriplex. halimus. Chafika REZKALLAH1*, Rachid DJEMAI1 Souhail MAALEM2 et Chamsseddine FEHDI2. 1Laboratoire d'écopédologie et de l'environnement, Université d'Annaba, Algérie. 2Département de Biologie, Université ...

  12. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    . ¹Laboratoire d'Ecologie et d'Environnement (LEE), Université Hassan ...... [20] - S. AZZAOUI, M. EL HANBALI et M. LEBLANC, « Cuivre, plomb, fer et manganèse dans le bassin versant du Sebou : Sources d'apport et impact sur la qualité des ...

  13. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    de l'eau / Journal of Water Science, vol. 20, n°3, (2007) p. 309-321. [19] - I. GUASMI, L. DJABRI, A. HANI et C. LAMOUROUX, « Pollution des eaux de l'Oued medjerda par les nutriments », Larhyss Journal, ISSN 1112-3680, n€ 05, (Juin 2006), pp.113-119. [20] - S. AZZAOUI, M. EL HANBALI et M. LEBLANC, « Cuivre, plomb ...

  14. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    géotechnique de l'aérodrome de Batna (N-E algérien). Article publié dans la revue Géotechnique. Française (2005) 69 – 74. [12] - S. KHALFAOUI, Evaluation géostatistique des paramètres géotechniques des sols du Nord- Est algérien. Thèse Doctorat, Université Badji Mokhtar Annaba – Algérie. (2008) 54 – 66. [13] - J. L. ...

  15. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    3-4-1. Prétraitement des données satellitaires. Avant de procéder à la stratification numérique de l'image satellitaire, une série d'opération de prétraitement sur ENVI est rendu nécessaire afin de faciliter son exploitation : - La correction géométrique ou le géoréférencement de l'image satellite Landsat TM7 par rapport aux.

  16. Etude des potentialites germinatives pour une regeneration ...

    African Journals Online (AJOL)

    Les différents aspects germinatifs du fruit de Neocarya macrophylla, ressource génétique fruitière spontanée du Niger, ont fait l'objet d'analyses. L'étude des performances germinatives de cette espèce a donc porté sur des graines récentes et des graines conservées à la température ambiante dans des flacons en verre ...

  17. Etude synonymique sur le genre Chrysochroa

    NARCIS (Netherlands)

    Kerremans, Ch.

    1897-01-01

    Cet opuscule était en partie terminé lorsque M. Ritsema eut l’obligeance de me soumettre un Chrysochroa qu’il croyait nouveau et dont il voulut bien me confier le soin de la description. Je ne pouvais mieux faire que d’intercaler celleci dans la présente étude et de confier cette dernière aux Notes

  18. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    L'application de l'éthephon (285 mg du principe actif dans 1 mL) sur les saignées de S. urens a permis d'augmenter la production de 3 g / arbre (187 cm de circonférence) pour le témoin à 473,87g / arbre en mars et 75,63 g /arbre en novembre [17]. A Daoudi, la production de gomme brute a atteint son pic durant la période ...

  19. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Cet article décrit la simulation et la conception d'un synthétiseur de fréquence destiné pour les applications des communications mobiles sur GSM. Dans ce travail, nous discutons les effets du bruit de phase dans chaque composant dans le circuit et les raies de référence sur les performances du système. Une évaluation ...

  20. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    Le suivi des modifications morphologiques en fonction des saisons de G. sesquipedale est effectué sur des échantillons représentatifs des 100 thalles prélevés ..... La période de septembre à janvier correspond à une phase de vieillissement des frondes qui se termine en janvier avec une détérioration des extrémités des ...

  1. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    φ' : Angle de frottement interne du sol (°). 5-2. Procédure géostatistique. La géostatistique est définie comme l'étude quantitative, à l'aide d'outils probabilistes, des phénomènes régionalisés. Par phénomène régionalisé, nous entendons un phénomène naturel qui se déploie dans l'espace. Cet espace est bien sûr le plus ...

  2. Study of zirconium and niobium purities during a chemical separation - measurement of the isotopes of the 95 chain; Etude de la purete du zirconium et du niobium au cours d'une separation chimique - mesure des isotopes de la chaine 95

    Energy Technology Data Exchange (ETDEWEB)

    Simonet, P.; Simonet, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    This study is usually done by {gamma} spectrometry; when Zr{sup 95} is contaminated by Nb{sup 95} or reciprocally their measurement becomes difficult because there is only a weak difference between energies of {gamma} rays. Proportions of Zr{sup 95} and Nb{sup 95} may be obtained quickly, whatever the age of the mixture, by a graphical method. The stabilizer of drift improves security in accuracy of results. In case of separation of Zr{sup 95} and Nb{sup 95} from two different phases, partition coefficients may be determined by measuring evolution of Nb{sup 95m} formed using the 17 keV X-ray; comparison with a theoretical curve representing the formation of Nb{sup 95m} let us have a great accuracy. Along this study we have been led to determine some nuclear constants which were insufficiently known, for instance we have measured the half life of Nb{sup 95m}, we got T = (90 {+-} 2) h and its branching ratio from the decay of Zr{sup 95}, we got K{sub m} = (8.0 {+-} 0.5)*10{sup -3}. [French] Cette etude s'effectue generalement par spectrometrie {gamma}. Dans le cas ou il y a pollution au Zr{sup 95} par le Nb{sup 95} ou inversement, leur mesure est rendue delicate par le fait que les rayonnements {gamma} emis sont d'energie tres voisines. La mesure graphique de l'emplacement en energie de l'axe du photopic complexe permet d'obtenir rapidement les proportions de Zr{sup 95} et de Nb{sup 95}, quel que soit l'age du melange. L'utilisation du correcteur de derive permet d'obtenir plus de securite dans la precision des resultats. Dans le cas de separation du Zr{sup 95} et du Nb{sup 95} dans deux phases differentes, on peut determiner les coefficients de partage des isotopes selon les phases en suivant l'evolution en fonction du tenps de la formation du Nb{sup 95m}. Nous effectuons des mesures sur la raie X a 17 keV la comparaison avec une courbe theorique de formation du Nb{sup 95m} donne une grande precision. Au cours de cette

  3. Preliminary study for a micro hydropower plant at La Poissine - Energy conversion from a water fall on the Arnon River at the location called 'La Poissine'; Etude preliminaire: petite usine hydroelectrique de la Poissine. Valorisation energetique d'une chute sur l'Arnon au lieu dit 'La Poissine'

    Energy Technology Data Exchange (ETDEWEB)

    Denis, V.

    2000-07-01

    objectifs en matiere de developpement durable fixes par le Canton, le service des batiments souhaite exploiter le debit derive de l'Arnon pour la pisciculture, de maniere a produire de l'electricite dans une proportion superieure ou egale a la consommation du batiment. Le laboratoire MHyLab a ete mandate pour realiser une etude de pre-faisabilite technique et economique de l'installation d'une mini-centrale hydro-electrique. L'etude preliminaire a envisage la possibilite d'installer soit une petite turbine hydraulique, soit une roue a eau de conception moderne. Les prix de revient calcules sans subsides sont compris entre 0.2 CHF/kWh et 0.33 CHF/kWh en fonction des scenarios consideres. Ce projet ecologiquement interessant est malheureusement fortement compromis par les couts de genie civil importants relativement a la production previsible. (author)

  4. Contribution to the study of once-forbidden {beta} transitions. Case of {sup 42}K and {sup 86}Rb; Contribution a l'etude des transitions {beta} une fois interdites. Cas de K{sup 42} et Rb{sup 86}

    Energy Technology Data Exchange (ETDEWEB)

    Andre, St. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-10-01

    An apparatus has been developed for studying the exact shape of the spectra of {beta} transitions which lead to an excited state of the final nucleus, using a Siegbahn-Slattis {beta} spectrometer. In particular the {beta} spectrum of the 2- {yields} 2+ transition of {sup 42}K has been measured; a considerable deviation has been found with respect to the statistical shape. The six elements of the nuclear matrices for this transition have been determined using this measurement and other results. It is shown that it cannot be explained by a pure f7/2 {yields} d3/2 transition. Furthermore the value obtained for the ratio of the matrix elements {integral}{alpha} and {integral}r is in excellent agreement with that predicted from the theory for the maintained vectorial current. (author) [French] On a realise et mis au point un appareillage permettant l'etude des formes precises des spectres {beta} des transitions aboutissant a un etat excite du noyau final sur un spectrometre {beta} Siegbahn-Slatis. On a mesure notamment le spectre {beta} de la transition 2- {yields} 2+ du K{sup 42}, mettant en evidence une deviation importante par rapport a la forme statistique. A partir de cette mesure et d'autres resultats, on a determine les six elements de matrice nucleaires de cette transition. On montre qu'elle ne peut pas etre expliquee par une transition f7/2 {yields} d3/2 pure. D'autre part, la valeur obtenue pour le rapport des elements de matrice {integral}{alpha} et {integral}r est en excellent accord avec celle qui est prevue a partir de la theorie du courant vectoriel conserve. (auteur)

  5. Modelisation et validation experimentale d'une pompe a chaleur geothermique a expansion directe

    Science.gov (United States)

    Beauchamp, Benoit

    Direct expansion ground source heat pumps are a technology which is actually gaining interest among scientific community. These systems operate on the well-known simple vapor compressor refrigeration cycle. The most popular heat pumps using a secondary ground loop also operate on the simple vapor compressor refrigeration cycle. The main difference between both technologies is that the ground heat exchanger is an integral component of the refrigeration cycle for the direct expansion systems. Therefore, the energetic and operational performances of the system are directly related to the working fluid behavior, the refrigerant, in relation with the diffusive ground heat transfer. The literature review indicates that scientific researches and publications related to direct expansion ground source heat pumps are limited. Therefore, regarding experimental results as well as simulation models, the actual information available in the scientific literature is not sufficient in order to obtain a satisfactory scientific appreciation of the technology. The main scope of the actual work is obtaining scientific experimental results regarding operational characteristics of such systems and also developing a numerical simulation model of a refrigerant-ground heat exchanger. The obtained experimental results will permit the analysis and comprehension of the complex dynamic operational characteristic of such systems, mainly regarding the refrigerant-ground heat exchanger. The simulation model developed will offer the possibility to realize parametric simulation for either the analysis or the development of refrigerant-ground heat exchanger. The system studied in this work is an available commercial unit and has the possibility to operate in both heating and cooling mode. When used in heating mode, the refrigerant-ground heat exchanger is the evaporator and consists of three ground loops in parallel having their own dedicated thermostatic expansion valve. When used in cooling mode, the refrigerant-ground heat exchanger is the condenser and consists of either one or a pair of ground loops in parallel. The operational situation is controlled by the onboard computer of the unit based on an operational sequence established from the manufacturer. The refrigerant-ground heat exchanger has the particularity to have a diffusive and transient heat transfer from the outer boundary of the refrigerant flow. The actually available models in the literature mainly solve a convective heat transfer at the outer boundary of the refrigerant flow. The development of a dynamic numerical model integrating the governing continuity, momentum and energy equations for the refrigerant fluid flow with transient ground heat transfer is a scientific contribution of the actual work. In order to obtain scientific experimental results from the system, a test rig has been build including a detailed instrumentation. Several experimental tests have been realized to obtain results for both the heating and cooling mode. Particular tests have also been conducted in order to obtain detailed results regarding the complex and dynamic operational characteristic of the ground loops in both heating and cooling mode. Experimental comparison of the numerical simulation model has been realized with the obtained experimental results.

  6. Moléculas orgánicas obtenidas en simulaciones experimentales del medio interestelar.

    Science.gov (United States)

    Muñoz-Caro, Guillermo Manuel

    Las nubes moleculares son regiones de formación de estrellas, con temperaturas cinéticas entre 10-50 K y densidades de 103-106 átomos cm-3. Su materia está formada por gas y polvo interestelar. Estas partículas de polvo están cubiertas por una fina capa de hielo, de unos 0.01 μm, que contiene H2O y a menudo CO, CO2, CH3OH y NH3. El hielo es presumiblemente irradiado por fotones ultravioleta y rayos cósmicos en las zonas poco profundas de las nubes moleculares y las regiones circunestelares. En un sistema de vacío, P ˜ 10-7 mbar, simulamos la deposición de hielo a partir de 10 K y la irradiación ultravioleta por medio de una lámpara de descarga de hidrógeno activada con microondas. La evolución del hielo se observa por medio de un espectrómetro infrarrojo. De este modo es posible determinar la composición del hielo observado en el medio interestelar y predecir la presencia de moléculas aún no detectadas en el espacio, que han sido producto del procesamiento del hielo en nuestros experimentos. También es posible calentar el sistema hasta temperatura ambiente para sublimar el hielo depositado. Cuando el hielo ha sido previamente irradiado, se observa un residuo compuesto por moléculas orgánicas complejas, algunas prebióticas, como varios ácidos carboxílicos, aminas, amidas, ésteres y en menor proporción moléculas heterocíclicas y aminoácidos. Algunas de estas moléculas podrían detectarse en estado gaseoso por medio de observaciones milimétricas y de radio. También podrían estar presentes en el polvo cometario, cuyo análisis químico está planeado por las misiones Stardust y Rosetta. Mientras tanto, nuestro grupo está llevando a cabo el análisis de partículas de polvo interplanetario (IDPs), algunas de las cuales pueden ser de origen cometario. Al igual que ocurre con los productos obtenidos por irradiación del hielo en nuestros experimentos, algunas IDPs son ricas en material orgánico que contiene oxígeno.

  7. Experimental diagenesis of quartz with petroleum; Diagenese experimentale du quartz en presence d'hydrocarbures

    Energy Technology Data Exchange (ETDEWEB)

    Teinturier, St.

    2002-11-01

    Quartz cementation has a great impact on petroleum reservoir quality by controlling the porosity and thus the gas or oil storage. However, the possible cementation of quartz during petroleum emplacement is still debated. In most cases, the reconstitution and the understanding of diagenetic processes is based on fluid inclusions studies. However, many questions concerning the representativeness and the reading of the fluid inclusions still remains misunderstood. The experiments were carried out in a silica{+-}water{+-}salts{+-}oil{+-}gas system with the objective to simulate the siliceous diagenesis of natural petroleum reservoirs and to better understand the mechanisms of fluid inclusions formation and quartz cementation in a water and/or petroleum system. Calibration curves have been established using Raman micro-spectroscopy and synthetic reference inclusions to calculate the methane content of aqueous inclusions in the H{sub 2}O-CH{sub 4}-NaCl system. A quantitative procedure for FT-IR micro-spectrometry has been developed to obtain, from individual petroleum fluid inclusions, mole % concentrations of methane, alkanes and carbon dioxide as constraints to thermodynamic modelling. Synthetic aqueous inclusions were created within quartz micro-fractures, with methane (from 150 deg C-200 bar), with petroleum (from 184 deg C-163 bar) and inside quartz overgrowth with the presence of hydrocarbons (from 277 deg C-300 bar). Synthetic petroleum inclusions were created with different water/oil ratios (W/O) within quartz micro-fractures (0

  8. Medicion y manipulacion de normas sociales en juegos experimentales de corrupcion

    National Research Council Canada - National Science Library

    Anabel Belaus; Cecilia Reyna; Esteban Freidin

    2016-01-01

    .... Para que capten conductas análogas a la realidad, es necesario que representen de manera apropiada las normas sociales que se ven transgredidas cuando hay corrupción. En esta revisión presentamos críticamente tres...

  9. La investigación-acción como medio para innovar en las ciencias experimentales

    OpenAIRE

    Diego-Rasilla, Francisco Javier

    2007-01-01

    Se realizó una investigación acción en enseñanza secundaria para potenciar el trabajo experimental en la enseñanza de las ciencias. Los propósitos de esta investigación acción fueron: (1) estimular el trabajo en equipo entre los profesores del Departamento de Ciencias, (2) fomentar la innovación en el aula, (3) incrementar de modo significativo el tiempo dedicado al trabajo en el laboratorio, (4) promover la formación del profesorado del Departamento de Ciencias mediante la investig...

  10. Caracterisation experimentale et numerique de la flamme de carburants synthetiques gazeux

    Science.gov (United States)

    Ouimette, Pascale

    The goal of this research is to characterize experimentally and numerically laminar flames of syngas fuels made of hydrogen (H2), carbon monoxide (CO), and carbon dioxide (CO2). More specifically, the secondary objectives are: 1) to understand the effects of CO2 concentration and H2/CO ratio on NOx emissions, flame temperature, visible flame height, and flame appearance; 2) to analyze the influence of H2/CO ratio on the lame structure, and; 3) to compare and validate different H2/CO kinetic mechanisms used in a CFD (computational fluid dynamics) model over different H2/CO ratios. Thus, the present thesis is divided in three chapters, each one corresponding to a secondary objective. For the first part, experimentations enabled to conclude that adding CO2 diminishes flame temperature and EINOx for all equivalence ratios while increasing the H2/CO ratio has no influence on flame temperature but increases EINOx for equivalence ratios lower than 2. Concerning flame appearance, a low CO2 concentration in the fuel or a high H2/CO ratio gives the flame an orange color, which is explained by a high level of CO in the combustion by-products. The observed constant flame temperature with the addition of CO, which has a higher adiabatic flame temperature, is mainly due to the increased heat loss through radiation by CO2. Because NOx emissions of H2/CO/CO 2 flames are mainly a function of flame temperature, which is a function of the H2/CO ratio, the rest of the thesis concentrates on measuring and predicting species in the flame as a good prediction of species and heat release will enable to predict NOx emissions. Thus, for the second part, different H2/CO fuels are tested and major species are measured by Raman spectroscopy. Concerning major species, the maximal measured H 2O concentration decreases with addition of CO to the fuel, while the central CO2 concentration increases, as expected. However, at 20% of the visible flame height and for all fuels tested herein, the measured CO2 concentration is lower than its stoechiometric value while the measured H2O already reached its stoechiometric concentration. The slow chemical reactions necessary to produce CO2 compared to the ones forming H2O could explain this difference. For the third part, a numerical model is created for a partially premixed flame of 50% H 2 / 50% CO. This model compares different combustion mechanisms and shows that a reduced kinetic mechanism reduces simulation times while conserving the results quality of more complex kinetic schemes. This numerical model, which includes radiation heat losses, is also validated for a large range of fuels going from 100% H2 to 5% H2 / 95% CO. The most important recommendation of this work is to include a NOx mechanism to the numerical model in order to eventually determine an optimal fuel. It would also be necessary to validate the model over a wide range for different parameters such as equivalence ratio, initial temperature and initial pressure.

  11. Efectos de las dietas experimentales en la respuesta inmune de los peces

    OpenAIRE

    Barandica Cañón, Lilian

    2010-01-01

    Descripció del recurs: el 14 de febrer de 2011 Los recursos pesqueros o acuícolas muestran cada vez mayor relevancia económica en todo el mundo debido al crecimiento de su demanda y a la creciente calidad del producto comercial. El conocimiento constante del estado de la población cultivada es fundamental, ya que frecuentemente cuando se detecta un problema es tarde para salvar la población. La correcta adaptación del animal a las condiciones de cultivo es fundamental en la piscicultura. C...

  12. Distribución de fuerzas en medios granulares no cohesivos: Observaciones experimentales y computacionales

    Directory of Open Access Journals (Sweden)

    Watson L. Vargas

    2005-01-01

    Full Text Available La comprensión de las propiedades mecánicas de los medios granulares es importante en aplicaciones de Ingeniería civil, Ingeniería química, ciencias geofísicas al igual que en otras áreas del conocimiento. Es bien sabido que las fuerzas dentro de un medio granular se distribuyen siguiendo una red altamente no-lineal de partículas bajo esfuerzo. Las fuerzas por arriba del promedio se concentran en una red de “cadenas de esfuerzo” que soportan la gran mayoría de la carga, mientras que existen partículas dentro del lecho que se encuentran prácticamente aisladas de sus vecinas y que no soportan carga alguna. Dado que las fuerzas inter-partícula y su distribución determinan las propiedades macroscópicas de un sistema granular, dicho comportamiento tiene consecuencias muy importantes en fenómenos de transporte tales como conducción de calor, propagación de sonido y conducción eléctrica. En este trabajo se presentan resultados de una investigación tanto experimental como computacional sobre el comportamiento de la distribución de esfuerzos en un medio granular estático. Los resultados expuestos proveen conocimientos nuevos sobre la física de medios granulares y complementan observaciones previas

  13. Implementación de biomodelos con fines experimentales y educativos una. experiencia multidisciplinaria

    OpenAIRE

    Marta Basualdo; Alfredo Rigalli; Antonio Rial; Adrian Barbosa

    2007-01-01

    Resumen: Se presenta un modelo matemático para emular el comportamiento endocrino de personas sanas o con la patología de Diabetes Mellitus Tipo I y Tipo II teniendo en cuenta la relación glucosa/insulina/glucagón a corto plazo. La estructura básica del modelo es de tipo compartimental, donde varios de sus parámetros se han adoptado en base a experimentos con modelos biológicos propios. Para ello se trabajó multidisciplinariamente en tres áreas que son Química Biológica, Ingeniería Química y ...

  14. Fisiopatología, tratamiento y modelos experimentales de artritis reumatoide

    OpenAIRE

    Miriam Noa Puig; Rosa Más Ferreiro; Sarahí Mendoza Castaño; Maikel Valle Clara

    2011-01-01

    La artritis reumatoide, poliartritis inflamatoria más común del adulto, que afecta cerca del 1 % de la población mundial, predomina más en mujeres que en hombres, se presenta con mayor frecuencia entre los 30 y 50 años de edad, y conlleva a una gran discapacidad del paciente. Se caracteriza por una sinovitis erosiva simétrica, en la cual el tejido conjuntivo prolifera (pannus), invade y erosiona el cartílago y el hueso de las articulaciones y, a veces, por una afectación multisistémica. En la...

  15. Reflujo gastroesofágico, características generales y modelos experimentales

    OpenAIRE

    Zullyt Zamora-Rodríguez

    2015-01-01

    La enfermedad de reflujo gastroesofágico (ERGE) es una enfermedad crónica recurrente que afecta a millones de personas en todo el mundo. Se realizó una revisión bibliográfica con el objetivo de abordar los principales aspectos de la ERGE, tal es el caso de su incidencia, la complejidad de su diagnóstico, que se encuentra basada en una primera fase, en la respuesta terapéutica frente a inhibidores de la bomba de protones y en segundo lugar, en el monitoreo del pH y los ácidos biliares, entre o...

  16. La ciencias experimentales y la enseñanza bilingüe

    Directory of Open Access Journals (Sweden)

    Aragón, Mª.M.

    2007-01-01

    Full Text Available A good knowledge of languages, an essential competence in this 21 th century society,is one of the target of the current curricula. The previous statement justifies that the bilingual teaching is increasing. The fact of including the experimental science in thebilingual projects would improve the linguistic competences and the science learning.

  17. Energy consumption of household refrigerator: experimentation and modelling; Interaction energetique batiment-equipement experimentale et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Saheb, Y.

    2003-12-01

    Monitoring projects showed that energy consumption of household refrigerators varies from 22% (Denmark) to 41% (Lebanon) of household electricity bill depending of use conditions. To study the influence of each use condition, we monitored during one week, energy consumption of two domestic refrigerators used in normal way by families in Algiers and the ambient temperature of each kitchen. From this, we found correlation between energy consumption of appliances and indoor air temperature. Then, we modelled the system. The equations of the refrigerant loop have been considered in a static mode and solved using Engineering Equation Solver, EES. While the refrigerator cabinet considered in a dynamic mode is a new TRNSYS Type. After that, we coupled this model to an existing building model, Type 56 of TRNSYS library. In the coupling model, the influence of indoor temperature and the heat rejected by the appliance are taken into account. In one hand, the simulation results showed that the influence of ambient temperature on energy consumption is more important for refrigerators with bad insulation. In the other hand, the improving of refrigerator insulation (class G to A) decreases by two-third the energy consumption. This study is supported by the French Agency for Environment and Energy Management. (author)

  18. Estudio acústico de las primeras edificaciones cistercienses de Santes Creus y Poblet. Resultados experimentales

    OpenAIRE

    González Baixauli, Genaro; Roig Fernández, José María; Daumal Domènech, Francesc de Paula; Esteve Agustench, Xavier

    2013-01-01

    Una vez fundado el monasterio cisterciense, se edificaba una pequeña capilla para el culto de los monjes antes de iniciar la construcción del conjunto arquitectónico. La capilla de Sant Esteve en Poblet y la capilla de la Trinitat en Santes Creus pertenecen a este grupo de edificaciones. La presencia de anacoretas en las primeras comunidades posiblemente influyó en el diseño acústico de estas, donde la inteligibilidad de palabra y oración era esencial. En esta comunicación se presentan los...

  19. An experimental propane bubble chamber; Sur une chambre a bulles experimentale a propane

    Energy Technology Data Exchange (ETDEWEB)

    Rogozinski, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1957-07-01

    Describes a propane bubble chamber 10 cm in diameter and 5 cm deep. The body of the chamber is in stainless steel, and it has two windows of polished hardened glass. The compression and decompression of the propane are performed either through a piston in direct contact with the liquid, or by the action on the liquid, through a triple-mylar-Perbunan membrane, of a compressed gas. The general and also optimum working conditions of the chamber are described, and a few results are given concerning, in particular, the tests of the breakage-resistance of the windows and the measurements of the thermal expansion of the compressibility isotherm for the propane employed. (author) [French] Description d'une chambre a bulles a propane de 10 cm de diametre et de 5 cm de profondeur. La chambre, dont le corps est en acier inoxydable, est munie de deux fenetres en verre poli et trempe. La compression et la detente du propane sont effectuees, soit a l'aide d'un piston en contact direct avec le liquide, soit en faisant agir sur ce dernier un gaz comprime a travers une triple membrane de teflon-mylar-perbunan. On decrit les conditions generales, ainsi que les conditions optimales de fonctionnement de la chambre et l'on signale un certain nombre de resultats obtenus concernant, notamment, les essais de resistance a la rupture des fenetres et les mesures de dilatation thermique de compressibilite isotherme du propane utilise. (auteur)

  20. LA ENSEÑANZA DE LA FÍSICA A TRAVÉS DE MODULOS EXPERIMENTALES

    Directory of Open Access Journals (Sweden)

    RONALD AVENDAÑO

    2012-07-01

    Full Text Available This proposal for teaching and learning physics was developed in two private educational institutions in Bogotá, Colombia. With students between 13 and 18 years old. We research different educational possibilities throughout experimental work in the classroom. We planed, applied and analyzed five modules for lab, eachone with small goals to achieve an overall objective. The process was designed according to the proper characteristics about physics topics and assembly dificulties. The modules were about; mechanics, electricity, thermodynamics, fluid mechanics and waves, by means of 5 modules that were titled: Tractor mechanic, Heat engine, Wind tunnel, Van Der Graff generator and Doppler effect. In general they consist on; design, construction, operation and explanation. We observed active participation of students on their learning process, interdisciplinary work, and reflections about science and technology impact over the society.

  1. Implementación de biomodelos con fines experimentales y educativos una. experiencia multidisciplinaria

    Directory of Open Access Journals (Sweden)

    Marta Basualdo

    2007-10-01

    Full Text Available Resumen: Se presenta un modelo matemático para emular el comportamiento endocrino de personas sanas o con la patología de Diabetes Mellitus Tipo I y Tipo II teniendo en cuenta la relación glucosa/insulina/glucagón a corto plazo. La estructura básica del modelo es de tipo compartimental, donde varios de sus parámetros se han adoptado en base a experimentos con modelos biológicos propios. Para ello se trabajó multidisciplinariamente en tres áreas que son Química Biológica, Ingeniería Química y Electrónica. El principal objetivo es demostrar la potencialidad educativa del modelo desde la óptica de las disciplinas antes mencionadas. Palabras clave: Modelo matemático biomédico, Educación multidisciplinaria, Experimentación, Control predictivo

  2. Team Modelling: Survey of Experimental Platforms (Modelisation d’equipes : Examen de plate-formes experimentales)

    Science.gov (United States)

    2006-09-01

    de formuler un certain nombre de recommandations à prendre en compte au titre de critères à appliquer à la nouvelle plate-forme de recherche...de travail, y compris, sur les plans matériel et cognitif , et les contraintes de temps, de même que les différents niveaux de la charge de travail...11 3.1.1 Agent Enabled Decision Group Environment (AEDGE) ........................................................... 11 3.1.2 Air Operation

  3. Ensayos experimentales en vigas de concreto postensado con tendones adheridos y no adheridos

    OpenAIRE

    Quintanilla Huayta, Darío

    2016-01-01

    En esta tesis se ha diseñado y ensayado cuatro vigas de concreto postensado con tendones adheridos y no adheridos para analizar su comportamiento en flexión. Se comparó el desempeño de ambos tipos de sistema de postensado basados en la resistencia en servicio, la resistencia máxima, las deflexiones, la recuperación de deflexión y el patrón de agrietamiento Las cuatro vigas tuvieron la misma sección “T” de concreto, establecida en base a un hipotético sistema de techo comparable con una lo...

  4. Fisiopatología, tratamiento y modelos experimentales de artritis reumatoide

    Directory of Open Access Journals (Sweden)

    Miriam Noa Puig

    2011-06-01

    Full Text Available La artritis reumatoide, poliartritis inflamatoria más común del adulto, que afecta cerca del 1 % de la población mundial, predomina más en mujeres que en hombres, se presenta con mayor frecuencia entre los 30 y 50 años de edad, y conlleva a una gran discapacidad del paciente. Se caracteriza por una sinovitis erosiva simétrica, en la cual el tejido conjuntivo prolifera (pannus, invade y erosiona el cartílago y el hueso de las articulaciones y, a veces, por una afectación multisistémica. En la mayoría de los pacientes la enfermedad sigue una evolución crónica fluctuante que, si no se trata, ocasiona una progresiva destrucción, deformidad e incapacidad de las articulaciones afectadas. La enfermedad evoluciona con cifras elevadas de factor reumatoideo y /o anticuerpos anti-citrulinas. Constituyen aspectos esenciales del tratamiento óptimo de la enfermedad: el diagnóstico diferencial precoz; el tratamiento inicial con antiinflamatorios no esteroideos; el uso de fármacos modificadores del curso de la enfermedad; el uso posible de glucocorticoides, a dosis bajas por vía oral, o en inyección intraarticular; la evaluación periódica de la adecuación del tratamiento (monitorización radiológica, sérica y funcional de la progresión de la enfermedad y de la toxicidad asociada al tratamiento, y las intervenciones de educación y rehabilitación del paciente. Para evaluar nuevas terapias para el tratamiento de la artritis reumatoide, los modelos más usados son: el de la artritis inducida por adyuvante en ratas y artritis inducida por colágeno en ratas y ratones. Otros modelos recientes muestran datos limitados. La eficacia de varios compuestos revela que su efecto terapéutico es más predictivo de eficacia clínica en humano cuando se estudian los modelos de artritis por adyuvante y por colágeno, que los datos de un solo modelo.

  5. Susceptibilidad a desinfectantes de Trichomonas vaginalis y Escherichia coli presentes en fómites experimentales

    Directory of Open Access Journals (Sweden)

    Fernando Anaya Velázquez

    2014-01-01

    Full Text Available Las enfermedades infecciosas provocadas por microorganismos patógenos se pueden transmitir directa o indirectamente. El protozoario Trichomonas vaginalis y la bacteria Escherichia coli son patógenos para el ser humano que pueden ser trans - mitidos por fómites. Existe una gama de productos para desinfectar, pero no existe información sobre el efecto completo de su eficacia en forma comparativa sobre bacterias o tricomonas en interacción con diferentes tipos de materiales. En este trabajo, se analizó el efecto de algunos desinfectantes sobre la viabilidad de Escherichia coli cepa 055 y Trichomonas vaginalis cepa GT-21, depositadas sobre diferentes tipos de materiales. Se diseñó un sistema in vitro con fómites experi - mentales para estudiar el efecto sobre estos patógenos. Se encontró que las tricomonas permanecen viables hasta ocho horas, y las bacterias hasta 24 horas en madera, papel, tela y plástico. Sin embargo, ambos microorganismos sobreviven solamente entre 1 y 4 horas sobre vidrio o metal. Tanto las bacterias como las tricomonas son inhibidas por los desinfec - tantes probados, siendo los más efectivos el etanol a 70% y el producto comercial Lysol ® .

  6. Susceptibilidad a desinfectantes de Trichomonas vaginalis y Escherichia coli presentes en fómites experimentales

    OpenAIRE

    Fernando Anaya Velázquez; Valeria Leyva Vera; Felipe Padilla Vaca; Itzel Páramo Pérez; Ángeles Rangel Serrano

    2014-01-01

    Las enfermedades infecciosas provocadas por microorganismos patógenos se pueden transmitir directa o indirectamente. El protozoario Trichomonas vaginalis y la bacteria Escherichia coli son patógenos para el ser humano que pueden ser trans - mitidos por fómites. Existe una gama de productos para desinfectar, pero no existe información sobre el efecto completo de su eficacia en forma comparativa sobre bacterias o tricomonas en interacción con diferentes tipos de materiales. En este traba...

  7. Conception et exploitation d'une structure active pour une aile laminaire adaptative experimentale

    Science.gov (United States)

    Coutu, Daniel

    This doctoral research contributed to the success of the project CRIAQ 7.1, demonstrating the capability of a morphing laminar wing to reduce fuel consumption. Respectively, this thesis shows the design of the experimental wing and its operation in a subsonic wind tunnel (Mach numbers of 0.2 to 0.3 with angles of attack between -1 and 2°). First of all, the morphing wing is formed of a composite laminate linked to an actuation system to build an active structure capable of modifying the wing upper surface geometry. The design was performed using a new developed methodology to solve aero-structural problems. Using ANSYS software, the finite elements method was applied to model the different possible active structure configurations Aerodynamic loads applied over the active structure as well as targeted morphed geometries have been provided by the Ecole Polytechnique team. Next, laminar flow enhancements allowed by each active structure configuration we' re evaluated using the aerodynamic solver XFoil 6.96. A best trade-off between aerodynamic performance and energy needed for wing morphing was found using a multi-objective optimization technique. Among the retained stable configurations, a 4-ply composite laminated shell driven by 2 actuation lines was retained. Thereafter, the research effort focused on the exploitation of the morphing capabilities of the experimental wing over each given set of flow conditions. Therefore, once the prototype was built, the structural model was refined, calibrated and coupled with the aerodynamic solver to accurately predict the aero-structural behavior in the wind tunnel. Optimal morphing wing shapes were numerically calculated using a generalized pattern search algorithm and a local search routine to refine the solution. In the wind tunnel, this open-loop control approach allowed an average 25% laminar flow regime extension over the wing prototype upper surface. Consequently, an average 18.5% profile drag reduction was measured by the pressure survey rake across the wake. Although these results were satisfactory, limitations in the aero-structural coupled model were observed when comparing numerical and experimental responses of the prototype. For that reason, the research continued with the development of a real-time optimization strategy in closed loop to exploit the complete potential of the morphing laminar wing. The wind tunnel balance was used as a hardware-in-the-loop returning the instantaneous lift-to-drag ratio to the optimizer. An optimization algorithm has been built to minimize the actuation required and thus reduce the time period until convergence to the optimal shape. To accelerate the search, numerically predicted actuation strokes (open loop) were used as initial modified shapes. As measured in the wind tunnel, the use of the closed-loop control strategy resulted in an average lift-to-drag ratio increase from 11 to 12.2% as compared to the open-loop approach. No more than 4 additional minutes were required to converge to the real-time optimized shapes, an acceptably small time delay on the cruise flight period time scale. Finally, infrared measurements performed byt the IAR-NRC team allowed experimental demonstration of the reciprocity between the laminar flow improvement and the lift-to-drag ratio increase. Keywords: morphing laminar wing, finite elements, design, active structure, composite structure, wind tunnel tests, multi-objective optimization, real-time optimization, actuators, shape memory alloy.

  8. DETERMINATION EXPERIMENTALE DU COEFFICIENT DE DISPERSION D’UNE MATRICE DE SOL

    Directory of Open Access Journals (Sweden)

    R MAOUI

    2005-06-01

    Full Text Available La caractérisation des interactions entre une espèce chimique et une matrice de sol est généralement considérée dans les études des phénomènes de transport. Ce type de réaction est assujetti à l’estimation du coefficient de dispersion D. Ce coefficient représente le gradient de concentration de l’élément et le flux de transport ; il dépend de la distribution de la vitesse, de la porosité du milieu et des courants du liquide. Le présent travail décrit le procédé expérimental et la technique associée utilisés en vue de quantifier le coefficient D de deux traceurs radioactifs. Les résultats obtenus à l’échelle du laboratoire sont très satisfaisants et restent en conformité avec les résultats publiés

  9. Study of the properties of an electron linac beam by means of the electromagnetic fields associated with the beam; Etude des proprietes du faisceau d'electrons d'un accelerateur lineaire au moyen des champs electromagnetiques associes a ce faisceau

    Energy Technology Data Exchange (ETDEWEB)

    Bergere, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    For measuring the diverse characteristic parameters of a Linac electron beam, the one method causing the least perturbation to the electron beam itself, consists in the detection of signals induced in certain types of detectors by the electromagnets fields associated with the beam. Some particular detectors are then described, for measuring the following characteristic parameters of a Linac electron beam; a) electron beam peak current, a) longitudinal dimension and density of an elementary electron bunch, c) phase position of the electrons on the travelling sine wave of the accelerating field, d) transverse position of the beam. These particular electrodes are then used to provide experimental data In order to check the theoretical computations giving the longitudinal and transversal motions Of the electrons during their acceleration. (author) [French] Parmi les methodes de mesure des diverses caracteristiques du faisceau d'electrons d'un accelerateur lineaire, celles qui perturbent le moins le faisceau sont les methodes dans lesquelles l'energie du signal de mesure provient de la perturbation par l'electrode de mesure des champs electromagnetiques associes au faisceau. On decrit les electrodes de ce type qui ont ete mises au point pour mesurer les caracteristiques suivantes du faisceau d'electrons: a) courant crete, b) extension en phase d'un paquet elementaire d'electrons, c) phase d'accrochage des electrons, d) position transversale moyenne des electrons. On decrit ensuite comment les signaux provenant de ces diverses electrodes peuvent etre utilises pour verifier experimentalement les previsions theoriques des mouvements longitudinaux et transversaux des electrons en cours d'acceleration. (auteur)

  10. Modelisations des effets de surface sur les jets horizontaux subsoniques d'hydrogene et de methane

    Science.gov (United States)

    Gomez, Luis Fernando

    Le developpement des codes et de normes bases sur une methodologie scientifique requiert la capacite de predire l'etendue inflammable de deversements gazeux d'hydrogene sous differentes conditions. Des etudes anterieures ont deja etabli des modeles bases sur les lois de conservation de la mecanique des fluides basees sur des correlations experimentales qui permettent de predire la decroissance de la concentration et de la vitesse d'un gaz le long de l'axe d'un jet libre vertical. Cette etude s'interesse aux effets de proximite a une surface horizontale parallele sur un jet turbulent. Nous nous interessons a son impact sur l'etendue du champ de la concentration et sur l'enveloppe inflammable en particulier. Cette etude est comparative : l'hydrogene est compare au methane. Ceci permet de degager l'influence des effets de difference de la densite sur le comportement du jet, et de comparer le comportement de l'hydrogene aux correlations experimentales, qui ont ete essentiellement etablies pour le methane. Un modele decrivant l'evolution spatio-temporelle du champ de concentration du gaz dilue est propose, base sur la mecanique des fluides computationnelle. Cette approche permet de varier systematiquement les conditions aux frontieres (proximite du jet a la surface, par exemple) et de connaitre en detail les proprietes de l'ecoulement. Le modele est implemente dans le code de simulations par volumes finis de FLUENT. Les resultats des simulations sont compares avec les lois de similitudes decoulant de la theorie des jets d'ecoulements turbulents libres ainsi qu'avec les resultats experimentaux disponibles. L'effet de la difference des masses molaires des constituantes du jet et des constituantes du milieu de dispersion est egalement etudie dans le contexte du comportement d'echelle de la region developpee du jet.

  11. Organisation of biological research carried out in the United States by the A.E.C. or under her contract (1960); Organisation des recherches biologiques menees aux Etats-Unis par l'A.E.C. ou sous son egide. Compte-rendu sommaire d'une mission d'etude (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Pellerin, J. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    This report is based on information gathered in the course of a trip to the United States, in November and December 1958 which consisted chiefly of visits to the main biological and medical research laboratories and discussions with the heads of these establishments. A description is given of the general organisation of the Atomic Energy Commission's Division of Biology and Medicine, and of the distribution of responsibility for radiation protection work and for biological, medical and agricultural research amongst the various Services attached to it; this is followed by a more detailed account of the activities carried on in this field at the great national laboratories. Finally, the systems of collaboration set up with external research organisations in the form of research contracts are examined, together with the substantial help provided by the A.E.C. for biological, medical and agricultural research in general, owing to a systematic policy of subsidising the distribution of radioisotopes for this purpose. (author) [French] Le present rapport a ete etabli sur la base des renseignements recueillis au cours d'un voyage d'etude aux Etats-Unis, en novembre et decembre 1958, comportant notamment la visite des principaux laboratoires de recherche biologique et medicale et des entretiens avec les principaux responsables de ces laboratoires. Apres une description de l'organisation generale de la 'Division of Biology and Medicine' de l'Atomic Energy Commission et de la repartition entre les divers Services qui lui sont rattaches des responsabilites concernant la protection contre les radiations et la Recherche biologique, medicale et agronomique, des indications plus detaillees sont donnees au sujet des activites poursuivies dans ce domaine au sein des grands laboratoires nationaux. Sont examinees enfin, l'importance et les modalites de la collaboration instituee avec les Organismes de Recherche exterieurs sous la forme de

  12. Security problems arising from the use of radioactive sources in the study of the wear in refractory linings; Les problemes de securite dans l'emploi de sources radioactives pour l'etude de l'usure de revetements refractaires

    Energy Technology Data Exchange (ETDEWEB)

    Courtois, G.; Hours, R.; Le Clerc, P.; Pons, A. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    poreux, a haut point de fusion et de grande inertie chimique. Dans ces sources, le radioelement peut etre soit enrobe de toute part par le pyrocerame, soit faire partie integrante de sa composition. Une etude comparative des deux types de sources est actuellement en cours. (auteur)

  13. Low-energy electron observation of graphite and molybdenite crystals. Application to the study of graphite oxidation; Observation au moyen d'electrons de faible energie de cristaux de graphite et de molybdenite. Application a l'etude de l'oxydation du graphite

    Energy Technology Data Exchange (ETDEWEB)

    David, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    The LEED study of cleaved (0001) faces of crystals having a layered structure allowed to investigate flakes free of steps on graphite and molybdenite, to show twinning on natural graphite. By intensity measurements and computation in the case of a kinematical approximation it has been possible to determine an inner potential of 19 eV for graphite and to identify the direction of the Mo-S bond of the surface layer of molybdenite. The oxidation of graphite has been studied by observing changes, in symmetry of the diffraction patterns and by mass spectrometry of the gases evolved during the oxidation. No surface compounds have been detected and the carbon layers appeared to be peeled off one after the other. The oxidation took place at temperatures higher than 520 C under an oxygen pressure of 10{sup -5} torr. (author) [French] L'etude par diffraction des electrons lents des faces (0001) de cristaux ayant une structure en feuillet a permis de mettre en evidence des plages sans gradins sur des clivages de graphite et de molybdenite caracterisees par la symetrie ternaire des diagrammes, de montrer l'existence de macles sur des cristaux de graphite naturel. Un calcul utilisant une approximation cinematique a ete applique aux intensites mesurees des taches de diffraction; il a ete ainsi possible de determiner un potentiel interne de 19 eV pour le graphite et de preciser la direction de la liaison Mo-S du feuillet superficiel de la molybdenite. L'oxydation du graphite a ete etudiee en mettant en relation des changements de symetrie des diagrammes de diffraction avec l'analyse des gaz provenant de la reaction carbone-oxygene. Il a ete montre qu'il n'y avait pas formation de composes de surface et que les couches de carbone etaient enlevees les unes apres les autres. L'oxydation a ete observee sous une pression d'oxygene de 10{sup -5} torr au-dessus de 520 C. (auteur)

  14. Contribution to the study of the structure and reactivity of ketones using deuterium substitution of the {alpha} - ketone hydrogens; Contribution a l'etude de la structure et de la reactivite des cetones, par utilisation de la substitution deuteriee des hydrogenes {alpha}-cetoniques

    Energy Technology Data Exchange (ETDEWEB)

    Frejaville, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-02-01

    This work is an attempt to obtain more knowledge about the structure and the reactivity of ketones; it is also a contribution to conformational analysis based on infrared signals associated with the C-D vibration in mono-deuterated compounds. In the first chapter the various dosage and synthetic methods used in this work are described. In the second chapter the infrared spectra in the 2100-2200 cm{sup -1} region for mono-deuterated ketones are interpreted on the basis of a simple model. This model is then studied in detail, and also critically and precisely, in the case of the mono deuterated acetone molecule. In the third chapter is studied the mechanism of the Favorskii reaction and the reactivity of all the {alpha}-ketonic hydrogens of 2 chloro-cyclohexanone are classified. In a technical appendix is described a counter-current exchange method for obtaining a great variety of solvents and deuterated pure raw materials under advantageous conditions. (author) [French] Ce travail est un effort vers une meilleure connaissance de la structure et de la reactivite des cetones; c'est egalement une contribution a l'analyse conformationnelle d'apres l'etude des signaux infrarouges associes a la vibration C-D dans les composes monodeuteries. Dans le premier chapitre sont decrites les differentes methodes de dosage et de synthese qui ont ete utilisees dans ce travail. Dans le deuxieme chapitre, les spectres infrarouges dans la region 2100-2200 cm{sup -1} de cetones monodeuteriees sont interpretes sur la base d'un modele simple. Ce modele est ensuite etudie de facon detaillee, critique et precise sur la molecule d'acetone monodeuteriee. Dans le troisieme chapitre on etudie le mecanisme de la reaction de FAWORSKII et l'on classe la reactivite de tous les hydrogenes {alpha}-cetoniques de la chloro-2-cyclohexanone. Dons l'appendice technique on decrit la mise en oeuvre d'un appareil d'echange a contre-courant qui permet d

  15. Contribution to the study of the mechanism of extraction of uranyl chloride by long chain aliphatic amines; Contribution a l'etude du mecanisme d'extraction du chlorure d'uranyle par les amines aliphatiques a longues chaines

    Energy Technology Data Exchange (ETDEWEB)

    Rubinstein, G.R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-06-01

    After having studied and developed the mechanisms which may 'a priori' explain the extraction process (co-ordination, ion association or intermediate mechanism), experience shows that ion association only should be taken into consideration. The structure of the organic complex of uranyl chloride has been defined on the basis of the study of the variation of the distribution coefficient of uranium between the two phases at the equilibrium as a function of successively the activity of Cl{sup -} ions in the aqueous phase, the concentration of amine salt in the organic phase and finally of the concentration of uranium in the aqueous phase. The plotting of the results in bi-logarithmic co-ordinates enables us to propose the following formula for the extracted compound: UO{sub 2}Cl{sub 4}{sup --}(NR{sub 3}H{sup +}){sub 2}. The calculation of the equilibrium constant of formation of the organic compound of uranyl chloride has been possible in the case of diluted solutions of uranium only. (author) [French] Apres avoir expose et developpe les mecanismes qui a priori pouvaient expliquer le processus d'extraction (coordination, association d'ions ou mecanisme intermediaire), le recours a l'experience a finalement permis de ne retenir que l'association d'ions. La structure du complexe organique de chlorure d'uranyle a ete definie a partir de l'etude de la variation du coefficient de partage de l'uranium entre les deux phases a l'equilibre en fonction successivement de l'activite des ions Cl{sup -} en phase aqueuse, de la concentration de sel d'amine en phase organique et enfin de la concentration d'uranium de la phase aqueuse. La representation bilogarithmique des resultats de ces essais a permis de proposer la formule suivante pour le compose extrait: UO{sub 2}Cl{sub 4}{sup --}(NR{sub 3}H{sup +}){sub 2}. Le calcul de la constante d'equilibre de formation du compose organique de chlorure d

  16. Study of the effect of neutron and electron irradiations on the low temperature thermal conductivity of germanium and silicon; Etude de l'effet des irradiations neutronique et electronique sur la conductibilite thermique aux basses temperatures du germanium et du silicium

    Energy Technology Data Exchange (ETDEWEB)

    Vandevyver, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-06-15

    The main results obtained from this work are the following: 1 Neutron irradiation (at 300 deg. K) produces lattice defects in germanium and silicon, and a corresponding very large lowering of the thermal conductivity is observed in the low temperature region (4-300 ). The results obtained have been explained with the help of the following hypotheses: for silicon a scattering of phonons by the stress fields produced by the defects; for germanium, a supplementary scattering of the electron phonon type. 2 Annealing treatments carried out on these materials above 373 deg. K restored the thermal conductivity over the whole temperature range of the measurements (4-300 deg. K); in the case of both germanium and silicon there were two steps in the annealing process. 3 A study of the thermal conductivity of germanium (initially P or N) after an electronic irradiation showed that the scattering of phonons could depend on the state of charge of the defects thus produced. (author) [French] Les principaux resultats obtenus au cours de ce travail sont les suivants : 1 Les irradiations neutroniques (a 300 deg. K) introduisent des defauts de reseau dans le germanium et le silicium et l'on observe correlativement pour ces materiaux, une tres importante diminution de conductibilite thermique dans le domaine des basses temperatures (4-300 deg. K). Les resultats obtenus ont pu etre interpretes en admettant principalement: pour le silicium, une diffusion des phonons par les champs de contrainte dus aux defauts; pour le germanium, une diffusion additionnelle du type electron-phonon. 2 Des recuits effectues sur ces materiaux au-dessus de 373 deg. K ont montre une restauration de la conductibilite thermique dans tout l'intervalle de temperature de mesure (4-300 deg. K) et comportant pour le germanium et le silicium, deux etapes de recuit 3 L'etude de la conductibilite thermique de germanium (initialement N ou P) apres une irradiation electronique, a montre que la diffusion

  17. Study of a pulsed discharge in hydrogen using the far ultraviolet emission of an additional element: electron temperature measurement; Etude d'une decharge pulsee dans l'hydrogene a partir de l'emission dans l'ultraviolet lointain d'un element additionnel: mesure de la temperature electronique

    Energy Technology Data Exchange (ETDEWEB)

    Schwob, J.L. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-06-15

    Ionization and excitation of an additional element in a pulsed annular discharge in hydrogen at low pressure (T.A.2000) are described by means of a simple coronal type analytical model. This model allows us to interpret the time variation of the intensity of spectral lines observed in the vacuum ultraviolet region. From this analysis two methods of electron temperature determination are deduced. The first method is based on the apparition time measurement of the intensity maximum for the spectral lines emitted from successive ions of the additional element (nitrogen). In the second method the electron temperature is determined from the intensity ratio of two spectral lines of an alkali-like ion. The transition couples (2s-2p, 2s-3p) and (2s-2p, 3s-3p) of C IV, N V and O VI have been used. The results obtained with these two independent methods are in good agreement. The electron temperature varies from a few electron-volts at the beginning of the discharge, to 70 eV at the time of N V emission (at 55 {mu}s), before the current maximum in the discharge (at 170 {mu}s). (author) [French] On etudie l'ionisation et l'excitation d'un element additionnel dans une decharge annulaire pulsee dans l'hydrogene sous faible pression (T.A.2000) a ralde d'un modele analytique simple du type coronal. Ce modele permet d'interpreter l'evolution de l'intensite des raies spectrales observees dans l'ultraviolet lointain. On deduit de cette etude deux methodes de determination de la temperature electronique. La premiere est basee sur la meaure des temps d'apparition des maximums d'intensite des raies emises par les ions successifs de l'element additionnel (azote). Dans la deuxieme methode la temperature est determinee a partir du rapport d'intensite des deux raies d'un ion alcalinoide. On a utilise les couples de transitions (2s-2p, 2s-3p) et (2e-2p, 3s-3p) des ions C IV, N V et 0 VI. Les resultats obtenus par ces deux

  18. Trends in incidence and early outcomes in a Black Afro-Caribbean population from 1999 to 2012: Etude Réalisée en Martinique et Centrée sur l'Incidence des Accidents Vasculaires Cérébraux II Study.

    Science.gov (United States)

    Olindo, Stephane; Chausson, Nicolas; Mejdoubi, Mehdi; Jeannin, Severine; Rosillette, Karine; Saint-Vil, Martine; Signate, Aissatou; Edimonana-Kaptue, Mireille; Larraillet, Veronique; Cabre, Philippe; Smadja, Didier; Joux, Julien

    2014-11-01

    Seldom studies are available on trends in stroke incidence in blacks. We aimed to evaluate whether stroke risk prevention policies modified first-ever stroke incidence and outcomes in the black Afro-Caribbean population of Martinique. Etude Réalisée en Martinique et Centrée sur l'Incidence des Accidents Vasculaires Cérébraux (ERMANCIA) I and II are 2 sequential prospective population-based epidemiological studies. There have assessed temporal trends in first-ever stroke incidence, risk factors, pathological types, and early outcomes in the black Afro-Caribbean population of Martinique comparing two 12-month periods (1998-1999 and 2011-2012). Crude and age-standardized incidence and 30-day outcomes for stroke in the 2 study periods were compared using Poisson regression. We identified 580 and 544 first-ever strokes in the 2 studies. World age-standardized incidence rates decreased by 30.6% in overall (111 [95% confidence interval, 102-120] versus 77 [95% confidence interval, 70-84]). Rate decline was greater in women than in men (34% versus 26%) particularly in women aged 65 to 74 years (-69%) and 75 to 84 years (-43%). Frequencies of hypertension and diabetes mellitus were unchanged, whereas dyslipidemia, smoking, and atrial fibrillation significantly increased. Only ischemic stroke types showed significant rate reduction in overall and in women, incidence rate ratio (95% confidence intervals) of 0.69 (0.50-0.97) and 0.61 (0.42-0.88), respectively. The overall 30-day case-fatality ratio remained stable (19.3%/17.6%), whereas a better 30-day outcome was found (modified Rankin Score, ≤2 in 47%/37.6%; P=0.03). Over 13 years, there has been a significant decrease (30.6%) in the age-specific first-ever stroke incidence in our Afro-Carribean population. Although prevention policies seem effective, we need to focus on new risk factors limitation and on male population adherence to prevention program. © 2014 American Heart Association, Inc.

  19. Surface integral formulation of Maxwell's equations for simulation of non-destructive testing by eddy currents. Preliminary study on the implementation of the fast multipole method; Formulation integrale surfacique des equations de Maxwell pour la simulation de controles non destructifs par courant de Foucault. Etude preliminaire a la mise en oeuvre de la methode multipole rapide.

    Energy Technology Data Exchange (ETDEWEB)

    Lim, T.

    2011-04-28

    numeriquement un controle non destructif par courants de Foucault (CND-CF), la reponse du capteur peut etre modelisee via une approche semi-analytique par integrales de volume. Plus rapide que la methode des elements finis, cette approche est cependant limitee a l'etude de pieces planes ou cylindriques (sans prise en compte des effets de bords) du fait de la complexite de l'expression de la dyade de Green pour des configurations plus generales. Or, il existe une forte demande industrielle pour etendre les capacites de la modelisation CF a des configurations complexes (plaques deformees, bords de piece...). Nous avons donc ete amenes a formuler differemment le probleme electromagnetique, en nous fixant comme objectif de conserver une approche semi-analytique. La formulation integrale surfacique (SIE) permet d'exprimer le probleme volumique en un probleme de transmission equivalent a l'interface (2D) entre sous-domaines homogenes. Ce probleme est ramene a la resolution d'un systeme lineaire (par la methode des moments) dont le nombre d'inconnues est reduit du fait du caractere surfacique du maillage. Des lors, ce systeme peut etre resolu par un solveur direct pour de petites configurations. Cela nous a permis de traiter plusieurs seconds membres (ie. differentes positions de capteurs) pour une seule inversion de la matrice d'impedance. Les resultats numeriques obtenus au moyen de cette formulation concernent des plaques avec la prise en compte des effets de bords tels que l'arete et le coin. Ils sont en accord avec des resultats obtenus par la methode des elements finis. Pour des configurations de grandes tailles, nous avons mene une etude preliminaire a l'adaptation d'une methode d'acceleration du produit matrice-vecteur intervenant dans un solveur iteratif (methode multipole rapide, ou FMM) afin de definir les conditions dans lesquelles le calcul FMM fonctionne correctement (precision, convergence...) dans le contexte CND

  20. Contributions a l'analyse de l'ecoulement et du transfert de chaleur dans les echangeurs de chaleur a plaques

    Science.gov (United States)

    Gherasim, Iulian

    Le but de la presente etude est d'elargir la base de connaissances sur l'ecoulement et le transfert de chaleur dans les echangeurs de chaleur a plaques. Pour cela, une etude experimentale et des simulations numeriques ont ete realisees. Le montage experimental a servi a valider le modele numerique et a explorer le regime de convection mixte. Le modele numerique represente fidelement l'ECP utilise dans ce travail, qui contient deux canaux confines par des plaques de type chevron. La validation a ete faite pour le regime laminaire et pour le regime turbulent, dans lequel un modele de turbulence a ete choisi comme le plus adequat, suite a une etude comparative entre plusieurs modeles. Le modele numerique a ete utilise pour completer les donnees experimentales et pour explorer des niveaux intangibles experimentalement. Ainsi, les champs thermique et d'ecoulement dans cet ECP ont ete etudies pour deux combinaisons de fluide : eau - eau et eau - huile de moteur. On a mis en evidence la non-uniformite du champ de temperatures et le fait que pour ce type particulier d'ECP, les fluides suivent preferentiellement deux passages lisses situes le long des bords des canaux. La dependance du nombre de Reynolds de ces phenomenes a ete mise en evidence. Le modele numerique a pu etre modifie pour evaluer l'effet des canaux lisses peripheriques sur le transfert de chaleur et les pertes de pression. Ce modele consiste de la meme geometrie, avec ces canaux peripheriques obtures. Cette comparaison montre que l'absence des passages lisses provoque l'augmentation du transfert thermique et aussi, des pertes de pression. Une autre modification portant sur la comparaison des configurations verticale et en diagonale a ete faite numeriquement. Des differences quantitatives insignifiantes concernant les performances thermiques et hydrauliques ont ete remarquees. Une investigation sur l'influence de la convection naturelle sur le transfert de chaleur et les pertes de pression a ete faite. Dans

  1. Study of the anodic process in the electrolysis of molten chlorides. Application to the chlorine electrode; Contribution a l'etude du processus anodique dans l'electrolyse des chlorures fondus. Application a l'electrode de chlore

    Energy Technology Data Exchange (ETDEWEB)

    Fondanaiche, J.C. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-05-01

    P (creee par un apport exterieur de chlore). Cette propriete de la reaction d'oxydation des ions Cl{sup -} nous a permis de proposer une methode electrochimique pour l'etude de l'equilibre d'absorption du chlore entre une phase solide et une phase liquide. Nous pouvons, en effet, remplacer l'apport exterieur de chlore sous une pression P par une electrolyse sous une densite de courant I. Nous avons developpe un schema qui rend compte de la cinetique de la reaction de decharge des ions Cl{sup -}. Il a ete verifie a l'aide des courbes intensite-potentiel et des courbes potentiel-temps caracterisant la depolarisation du carbone en circuit ouvert. Deux methodes ont ete utilisees pour la mesure de la quantite de chlore adsorbe sur le carbone. Les liaisons des molecules de chlore adsorbe sur le carbone et la surface d'echange electrode-electrolyte ont pu etre precisees en faisant varier la temperature, la nature de l'electrode et de l'electrolyte. Certaines anomalies et en particulier certains phenomenes transitoires, ont ete expliques par l'influence de l'oxygene present dans le sel fondu sous forme d'ions O{sup 2-} et a la surface de l'electrode, sous forme de complexes de chimisorption. (auteur)

  2. Study of total ionization by {alpha} particles, in pure gases and gaseous mixtures containing metastable atoms, as a function of temperature; Etude de l'ionisation totale par les paricules {alpha}, dans les gaz purs et les melanges gazeux contenant des atomes metastables, en fonction de la temperature

    Energy Technology Data Exchange (ETDEWEB)

    Bristeau, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    Experiments have been carried out on the total ionization by alpha particles, in pure gases and gaseous mixtures containing metastable atoms, as a function of temperature. Using a different experimental method, the results for the mean ionization energy at 300 K given by Jesse in 1953 have been confirmed to within 1 per cent. It is established that in pure gases the mean energy W required to form a pair of ions remains constant as the temperature varies from 77 to 300 K. It is shown that there is a temperature effect for W in binary gas mixtures of the type A-B containing meta-stable atoms A{sup *} and an 'impurity' B. A systematic study is made of the change {delta}W in W as a function of the temperature and of the B 'impurity' concentration in the mixtures Ne - Ar, Ne - Kr, Ne - H{sub 2}, Ne - N{sub 2}, Ne - CH{sub 4} and He - Ar. Experiments have been carried out on a ternary gas mixture of the type A - B - C, where C is a second ionizable 'impurity' added to the binary mixture A - B; they show the existence of excited atoms B{sup *} formed from the 'impurity' B. Finally, it is shown that the amount of metastable atoms formed in a pure gas must be very close to the number N{sub 0} of ion pairs, and that there must exist a correlation between the number N{sub 0} of ion pairs and the number {approx_equal} N{sub 0} of metastable atoms created in the pure rare gases. (author) [French] On realise des experiences sur l'ionisation totale par les particules alpha, dans les gaz purs et les melanges gazeux contenant des atomes metastables, en fonction de la temperature. Avec une methode experimentale differente, on retrouve a mieux que 1 pour cent pres les valeurs de l'energie moyenne d'ionisation que JESSE a obtenues en 1953 et a 300 K. On etablit que dans les gaz purs, l'energie moyenne W pour creer une paire d'ions demeure constante, quand la temperature varie entre 77 et 300 K. On met en evidence un

  3. An overview of chloro-hydrocarbon decontamination of groundwater and the unsaturated zone in the Czech Republic: a consequence of old contamination problems; Revue de la depollution des hydrocarbures dans les nappes et dans leur zone non saturee en Republique tcheque: consequence de pollutions anciennes

    Energy Technology Data Exchange (ETDEWEB)

    Zikmund, V.; Boukalova, Z. [GEO s.r.o., Jana Masaryka, Praha (Czech Republic); Zelinka, Z. [VZ GLS a.s., K Botiei, Praha (Czech Republic)

    1999-07-01

    A range of long-standing contamination problems in the Czech Republic have been addressed since 1992. The major task is the removal of chloro-hydrocarbons, mainly 1,1 dichloro-ethylene (1,1 DCE), 1,2 dichloro-ethylene (1,2 DCE), 1,1,2 trichloroethylene (TCE) and 1,1,2,2 tetra-chloro-ethylene (PCE), from both ground-water and the unsaturated zone. In the case of the unsaturated zone, the most seriously polluted soils are excavated and removed, while the less affected areas are established using venting techniques, the efficiency of which can be assessed by measuring the concentrations of volatile CLHCs in the soil, in the venting system and at the output of the filters. For the saturated zone, it is stripping techniques that are the most suitable and most often applied in groundwater remediation projects. An important supplement to all remediation projects is the monitoring of catchment areas in order to identify sites that remain affected by groundwater pollution. (authors)

  4. Use of the tritium thermonuclear peak in the deep unsaturated zone for quantitative estimate of aquifer recharge under semi-arid conditions: first application in Sahel. La recherche du pic de tritium thermonucleaire en zone non saturee profonde sous climat semi-aride pour la mesure de la recharge des nappes: premiere application au Sahel

    Energy Technology Data Exchange (ETDEWEB)

    Cheikh Becaye Gaye (Dakar Univ. (Senegal)); Aranyossy, J.F.

    1992-08-01

    The location of the bomb tritium signal at 20 and 12 m depth in the unsaturated sand dunes in the semi-arid part of North Senegal leads to a qualitative estimate of the effective infiltration of 22 and 26 mm.yr{sup -1}. These figures correspond respectively to 6.5 and 8% of the total precipitation since 1963. Tritium content distribution in interstitial water is modelled by convolution of the analytical solution of the dispersion equation. Best fitting of the complete 12 m depth tritium peak is obtained with a dispersion coefficient of 0.03 m{sup 2}.yr{sup -1}.

  5. Uranium migration in a podzol. The role of colloids in the non-saturated zone and the phreatic water: application to the Landes de Gascogne area; Migration de l'uranium dans un podzol. Le role des colloides dans la zone non saturee et la nappe: application aux Landes de Gascogne

    Energy Technology Data Exchange (ETDEWEB)

    Crancon, P

    2001-01-01

    The non-saturated zone of a soil represents the interface between the atmosphere and the phreatic water. The confinement efficiency of the non-saturated zone above the phreatic water depends on the fastness of water transfers and on the type of pollutant transport mechanisms. Uranium (VI) can combine with humid acids to form very stable complexes. The aggregates of the absorbing complex are highly sensible to the variations of the ionic force of the environment. This sensitiveness can be at the origin of a strong remobilization of the colloid humic compounds of the soil, and of their migration towards the underground water. In this situation, the uranium complexed by humic compounds can rapidly migrate in the soil. The comparative reactive transport of the total uranium and its isotopes has been studied in a site, the Landes de Gascogne podzol (SW France), where metallic uranium has been sprinkled on the surface of the soil. The field study has been completed with an experimental column transport study using uranium isotopes tracer techniques. The field study shows that most of uranium is trapped in the very first cm of the soil. However, anomalous high uranium concentrations are observed in underground waters, more than 2 km away from the contaminated areas. This demonstrates that a fast and long distance transport process exists for uranium in the unsaturated zone. In the sandy soil of the study area, natural argillo-humic colloids migrate with the velocity of water but can be delayed when the ionic force of the underground waters increases. It is shown that uranium is strongly linked with the thin grain size fraction (< 8 {mu}m) of the sand, and more particularly with the argillo-humic composite colloids. In the stable geochemical conditions of the experimental columns, more than 70% of uranium is trapped in the first 2 cm of the sand, even after the circulation of 100 volumes of water inside the column. This shows the strong trapping capacity of the Landes sand. The addition of natural colloids to the injected solution favors the migration of uranium. Between 5 and 15% of the total uranium input is transported by argillo-humic colloids at water speed. The use of {sup 233}U allows to discriminate between the uranium transported through the sand in a non-reactive way, and the uranium desorbed from the argillo-humic aggregates and the sand grain coatings. A fast reduction of the ionic force of the environment during the tests shows an important remobilization of uranium from the soil. When the complex relations between hydrology and geochemistry in the unsaturated zone are considered, it appears that uranium transport is controlled: by the ionic force and pH value disturbances as an answer to rain water infiltration or phreatic water rises, and by the existence of an acidity and dissolved oxygen stratification in the soil which determines the speciation of uranium and the efficiency of sorption at the surface of soil minerals and colloids above the free surface of the phreatic water. (J.S.)

  6. The use of probe characteristics in plasma in the presence of a magnetic field (1960); Utilisation des caracteristiques de sondes dans des plasmas en presence de champ magnetique (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Brunet, A.; Geller, R.; Leroy, J. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    In this article we recall the principal methods of interpretation of probe characteristics in plasma in the presence of magnetic fields. Our purpose is to resume and to present the methods in such a form as to be immediately applicable in a particular case. This article is therefore principally useful to experimenters. Finally we expose our practical view points by comparing of experimental methods. (author) [French] Dans cet article, nous rappelons les principales methodes d'interpretation des caracteristiques de sonde dans des plasmas en presence de champs magnetiques. Notre but est de resumer et de presenter sous forme inmediatement applicable ces methodes. Cet article est donc destine aux experimentateurs. Enfin, nous developpons nos etudes pratiques sur la question en etablissant des comparaisons experimentales entre les methodes. (auteur)

  7. Fisiopatología, tratamiento y modelos experimentales de artritis reumatoide Pathophysiology, treatment and experimental models of rheumatoid arthritis

    Directory of Open Access Journals (Sweden)

    Miriam Noa Puig

    2011-06-01

    Full Text Available La artritis reumatoide, poliartritis inflamatoria más común del adulto, que afecta cerca del 1 % de la población mundial, predomina más en mujeres que en hombres, se presenta con mayor frecuencia entre los 30 y 50 años de edad, y conlleva a una gran discapacidad del paciente. Se caracteriza por una sinovitis erosiva simétrica, en la cual el tejido conjuntivo prolifera (pannus, invade y erosiona el cartílago y el hueso de las articulaciones y, a veces, por una afectación multisistémica. En la mayoría de los pacientes la enfermedad sigue una evolución crónica fluctuante que, si no se trata, ocasiona una progresiva destrucción, deformidad e incapacidad de las articulaciones afectadas. La enfermedad evoluciona con cifras elevadas de factor reumatoideo y /o anticuerpos anti-citrulinas. Constituyen aspectos esenciales del tratamiento óptimo de la enfermedad: el diagnóstico diferencial precoz; el tratamiento inicial con antiinflamatorios no esteroideos; el uso de fármacos modificadores del curso de la enfermedad; el uso posible de glucocorticoides, a dosis bajas por vía oral, o en inyección intraarticular; la evaluación periódica de la adecuación del tratamiento (monitorización radiológica, sérica y funcional de la progresión de la enfermedad y de la toxicidad asociada al tratamiento, y las intervenciones de educación y rehabilitación del paciente. Para evaluar nuevas terapias para el tratamiento de la artritis reumatoide, los modelos más usados son: el de la artritis inducida por adyuvante en ratas y artritis inducida por colágeno en ratas y ratones. Otros modelos recientes muestran datos limitados. La eficacia de varios compuestos revela que su efecto terapéutico es más predictivo de eficacia clínica en humano cuando se estudian los modelos de artritis por adyuvante y por colágeno, que los datos de un solo modelo.The rheumatoid arthritis, is the inflammatory polyarthritis commonest in adults affecting about the 1 % of world population, more predominant in women than men and more frequent in those aged 30 and 50 and entails a high level of inability of patient. It is characterized by a symmetrical erosive synovitis with proliferation of conjunctival tissue (pannus, invading and eroding the cartilage and joint bones, and sometimes, by a multisystem affection. In most patients the disease follows a fluctuating chronic course, which it is not treated, provoke a progressive destruction, deformity and inability of involved joints. The disease evolves with high figures of rheumatoid factor and/or anti- citrulline antibodies. These are essential features of an optimal treatment of this entity include: early differential diagnosis, initial treatment with non-steroidal anti-inflammatory drugs (NSAIDs, the use of disease course modifying drugs, the potential use of oral low-dose glucocorticoid agents or intra-articular injections, and a periodical assessment of treatment fitting (radiological serum and functional monitoring of disease progression and of treatment-associated toxicity and the educational and rehabilitations interventions of patient. To assess the new therapies for treatment of rheumatoid arthritis, the more uses models are: that of the arthritis induced by adjuvant drugs in rats and the arthritis induced by collagen in rats and mice. Other new models show limited data. Effectiveness of several compounds reveals that its therapeutic effect is more predictive of the clinical effect in the human being when models of arthritis due to adjuvant drugs and collagen than data from an only one model.

  8. Técnicas experimentales para el estudio de la angiogénesis en enfermedades reproductivas femeninas

    OpenAIRE

    Scotti, Leopoldina; Abramovich, Dalhia Nurit; Irusta, Griselda; Pazos Maidana, María Camila; Pascuali, Natalia Marisa; Haro Durand, Luis Alberto; Tesone, Marta; Parborell, Maria Fernanda Agustina

    2016-01-01

    El desarrollo vascular en el tracto reproductivo femenino es un proceso que se encuentra restringido a la formación del cuerpo lúteo y a la proliferación del endometrio uterino durante los ciclos menstruales. Se han identificado numerosos inductores de la angiogé- nesis, que incluyen, entre otros, los miembros del factor de crecimiento fibroblástico (FGF) y la familia del factor de crecimiento del endotelio vascular (VEGF), angiopoyetinas (ANGPT), factor de crecimiento transformante (TGF) y f...

  9. FILOSOFIA DE LA MENTE; APORTES TEORICOS Y EXPERIMENTALES A LA VISIÓN EMERGENTISTA DEL VINCULO MENTE-CEREBRO.

    Directory of Open Access Journals (Sweden)

    Paul Ruiz Santos

    2011-01-01

    Full Text Available El presente trabajo intenta sumar alprograma emergentista dentro del mapa teórico referido a la Filosofía de la Mente, tomando como referentes a disciplinas y teorías naturalizadas. Algunos puentes vinculantes desde la naturalización pueden ser por ejemplo el neuro-psicoanálisis, las neuronas espejo, la psicosomática, entre otros. Dichos puentes son posibles de ser tendidos a través de la naturalización de los procesos psicológicos vinculándolos a diferentes procesos biológicos. El objetivo del trabajo no pretende obturar los procesos psicológicos a través de la simplificación y reduccionismo de los mismos, ni biologizar la psicología a través de planteos cartesianos. Sino, de la mano de la neuro-fenomenología, acceder a más y nuevas evidencias sobre el vínculo mente-cerebro y sus implicancias aportando a una visión interaccionista y emergentista del vínculo.

  10. Bases fisiológicas experimentales para el estudio de la patogenia de los temblores en la enfermedad de parkinson

    OpenAIRE

    Esguerra Gómez, Alfonso; Matallana T., Alfonso; Montes D., Gonzalo

    2011-01-01

    Se presenta un estudio experimental sobre el fenómeno de la "contracción prosténica" del músculo gastrocnemio de la rana o "tétanos rítmico" de C. Richet. Finalmente, se presenta un análisis comparativo de las condiciones halladas en Fisiología humana para sugerir la posibilidad de encontrar en los casos clínicos de temblores una patogenia semejante al mecanismo de producción del tétanos rítmico experimental.

  11. Determinacion de las relaciones polimorficas entre Teladorsagia circumcincta (Stadelmann, 1894 y Teladorsagia trifurcata (Ransom, 1907 en condiciones experimentales

    Directory of Open Access Journals (Sweden)

    G. Morales

    1985-03-01

    Full Text Available En el presente estudio se demostró que Teladorsagia circumcincta (Stadelmann, 1894 y T. trifurcata (Ransom, 1907, nemátodes Trichostrongylidae de la sub-família Ostertagiinae, parasitan un espectro de hospedadores similares. La ausencia de barreras reproductivas entre T. trifurcata y T. circumcincta, así como la estabilización rápida de las proporciones de las dos entidades en el seno de la población, evidencia que T. trifurcata es un morfo de T. circumcincta.It is shown in this study that two species of nematodes: Teladorsagia circumcincta (Stadelmann, 1894 and T. trifurcata (Ransom, 1907, (Nemátoda, Trichostrongylidae, subfamily Ostertagiinae, have a similar range of host species. Furthermore, the abscence of reproductive barriers, as well as the fact that both forms soon reach stable proportions in the host population, indicate that T. trifurcata is a morph of T. circumcincta.

  12. Hacia la esencia de la arquitectura: el papel de Oriente en los años experimentales de Miguel Fisac

    Directory of Open Access Journals (Sweden)

    Óscar Lorente Alcoya

    2013-07-01

    Full Text Available Tanto la arquitectura tradicional japonesa como los pensamientos del filósofo chino Lao zi son referencias fundamentales en la obra de Miguel Fisac, uno de los arquitectos españoles más destacados de la segunda mitad del siglo XX. A pesar de haber reconocido estas influencias en numerosas ocasiones, este hecho todavía no ha sido objeto de un estudio profundo. Sin embargo, el análisis de su obra y de su interés por Japón, a donde viajó varias veces, pone de relieve que la arquitectura española fue permeable a este influjo. El presente artículo aporta una visión más completa de la evolución de Fisac y ofrece un panorama histórico de su desarrollo durante las décadas de los años cuarenta y cincuenta, cuando concibió su personal concepto de la arquitectura tomando ideas de diferentes fuentes, entre las que Oriente se encuentra en un lugar principal. Además, se examina en detalle la repercusión que el contacto con la arquitectura japonesa tuvo en su producción.

  13. Fisiopatología, tratamiento y modelos experimentales de artritis reumatoide Pathophysiology, treatment and experimental models of rheumatoid arthritis

    OpenAIRE

    Miriam Noa Puig; Rosa Más Ferreiro; Sarahí Mendoza Castaño; Maikel Valle Clara

    2011-01-01

    La artritis reumatoide, poliartritis inflamatoria más común del adulto, que afecta cerca del 1 % de la población mundial, predomina más en mujeres que en hombres, se presenta con mayor frecuencia entre los 30 y 50 años de edad, y conlleva a una gran discapacidad del paciente. Se caracteriza por una sinovitis erosiva simétrica, en la cual el tejido conjuntivo prolifera (pannus), invade y erosiona el cartílago y el hueso de las articulaciones y, a veces, por una afectación multisistémica. En la...

  14. Explicando el paleoamericano y su probable extinción, a través de inferencias comparativas y experimentales

    Directory of Open Access Journals (Sweden)

    Héctor M. Pucciarelli

    2009-07-01

    Full Text Available Sobre la base de estudios previos, se inició una búsqueda puntual de muestras conteniendo presuntos paleoamericanos y amerindios intramuestrales que en proporciones variables se descubrieron en la base craneofuncional América 12.sys . Se trabajó con 49 muestras, ordenadas de a siete muestras por grupo, en siete grupos con contenido paulatinamente decreciente en la proporción de paleoamericanos. El objeto fue lograr un modelo que simule un efecto migración-reemplazo, en el que los paleoamericanos deberían disminuir paulatinamente en función del incremento de los amerindios. Una proporción cercana a cero al final de la prueba sugeriría la presencia del efecto buscado, esto es, el reemplazo total de los paleoamericanos por los amerindios. Sólo las dos primeras muestras del grupo I contuvieron el 100% de paleoamericanos (pericues y algonquinos, mientras que las cinco restantes del mismo grupo, fueron Lagoa Santa, Lauricocha, Aguazuque, Checua y Tequendama-Mosquera. Todas ellas con proporciones variables de componente amerindio. Fue obtenido que: a los paleoamericanos integraban al principio del experimento el 100% de las muestras estudiadas; mientras que hacia el final del proceso quedaron reducidos a menos del 3%; b este proceso no fue brusco sino paulatino y se hizo efectivo a lo largo de las siete etapas que demandó la simulación, a fin de llegar a un valor cercano a cien (97,6% de saturación amerindia, lo cual implica ser causa probable —según propone el modelo— de la posible extinción de los paleoamericanos por saturación poblacional del componente amerindio.

  15. The turbulent viscosity models and their experimental validation; Les modeles de viscosite turbulente et leur validation experimentale

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This workshop on turbulent viscosity models and on their experimental validation was organized by the `convection` section of the French society of thermal engineers. From the 9 papers presented during this workshop, 8 deal with the modeling of turbulent flows inside combustion chambers, turbo-machineries or in other energy-related applications, and have been selected for ETDE. (J.S.)

  16. Evolución y nuevos retos de la didáctica de las ciencias experimentales

    Directory of Open Access Journals (Sweden)

    2012-01-01

    Full Text Available Este estudio presenta una revisión de los contenidos para la enseñanza de la llamada "naturaleza de la ciencia" (y tecnología desde las diversas aportaciones de la investigación didáctica especializada sobre estas cuestiones. La visión que se presenta aquí está relacionada con y es dependiente de diversos conceptos modernos, tales como la situación de profunda interacción entre ciencia y tecnología en la actividad científica actual (tecnociencia, que se traduce en una visión de la educación científica donde también se integra la tecnología; el lema de la alfabetización científica y tecnológica para todos, como guía general para lograr educar la competencia científica de los estudiantes; y la naturaleza de la ciencia (y tecnología como componente innovador de la alfabetización para todos. La revisión presenta las diversas propuestas de contenidos básicos para la enseñanza de la naturaleza de la ciencia (y tecnología que se manejan usualmente en la literatura especializada, con el fin de iluminar la selección de los contenidos curriculares y contextualizar mejor las propuestas del currículo español de ciencias (que se abordará en la segunda parte de este estudio. El objetivo es ayudar al profesorado a clarificar los contenidos enseñables y aportar sentido a los nuevos contenidos en los currículos españoles de ciencias acerca de estas complejas cuestiones.

  17. Trasnferencia de Energía en NP de polimeros conjugados: modelado y contraste con datos experimentales

    OpenAIRE

    Bellomo, Franco; Bellomo, Lucas; Bellomo, Daniel; Ponzio, Rodrigo; Palacios, Rodrigo

    2015-01-01

    Los polímeros conjugados son macromoléculas compuestas por monómeros que presentan enlaces simples y múltiples alternados. Dentro de la cadena existen segmentos (cromóforos) de longitud variable en donde los electrones π se encuentran deslocalizados. Debido a la heterogeneidad estructural de estos materiales, los procesos de transferencia de energía (TE) entre cromóforos y dopantes son altamente complejos. El mejor entendimiento de estos procesos es de importancia para el desarrollo de dispos...

  18. Efecto de agonistas cannabinoides en modelos experimentales de neuropatía autonómica cardiaca

    OpenAIRE

    González Fernández, Cristina

    2014-01-01

    Tesis Doctoral leída en la Universidad Rey Juan Carlos de Madrid en 2014. Directores de la Tesis: María Isabel Martín Fontelles y Visitación López-Miranda González En la actualidad, el aumento de la esperanza de vida se asocia con una mayor incidencia y prevalencia de enfermedades crónicas como la Diabetes Mellitus (DM), el síndrome metabólico (SM), el cáncer o algunas patologías inflamatorias (Fontana y cols, 2014). Tanto la propia enfermedad como la terapéutica de las mismas pueden afect...

  19. Pastas de relleno para reintegración volumétrica de esculturas en cera. Primeros resultados experimentales

    Directory of Open Access Journals (Sweden)

    Nerea del Moral Azanza

    2014-12-01

    Full Text Available La conservación de esculturas en cera supone un gran reto para el restaurador al tratarse de un material que presenta diversas dificultades derivadas tanto de sus propiedades físicas como de sus procesos de envejecimiento natural. Con el tiempo, los propios materiales adicionados a la cera para la preparación de las pastas de modelar sufren transformaciones químicas que ocasionan un aumento de la fragilidad en este tipo de objetos. Este hecho unido a la acción de agentes de degradación externos, sobre todo cambios bruscos de temperatura, en el ambiente expositivo puede conllevar la formación de micro-fisuras y grietas, y en grado extremo la existencia de fracturas y pérdidas del material, haciendo necesario efectuar tratamientos de reintegración en las zonas dañadas. Este trabajo muestra los primeros resultados obtenidos tras someter a estudio ciertas características físicas de la cera, a fin de desarrollar un método científico de intervención en lagunas. Se ha partido de ocho posibles pastas de relleno para analizar sus intervalos de fusión y su comportamiento tras ser sometidas a envejecimiento artificial, con el objetivo de encontrar una pasta idónea para la restauración de los modelos anatómicos en cera de la colección Javier Puerta de la Universidad Complutense de Madrid. Los resultados que se exponen podrían ser aplicables a otras colecciones de ceroplástica y/o artefactos en cera.

  20. Stratification of bubbly horizontal flows: modeling and experimental validation; Stratification des ecoulements a bulles horizontaux: modelisation et validation experimentale

    Energy Technology Data Exchange (ETDEWEB)

    Bottin, M.

    2010-12-17

    Hot films and optical probes enabled the acquisition of measurements in bubbly flows at 5, 20 and 40 diameters from the inlet of the vein on the METERO facility which test section is a horizontal circular pipe of 100 mm inner diameter. The distribution of the different phases, the existence of coalescence and sedimentation mechanisms, the influence of the liquid and gas flow rates, the radial and axial evolutions are analyzed thanks to fast camera videos and numerous and varied experimental results (void fraction, bubbles sizes, interfacial area, mean and fluctuating velocities and turbulent kinetic energy of the liquid phase). Some models, based on the idea that the flow reaches an equilibrium state sufficiently far from the inlet of the pipe, were developed to simulate mean interfacial area and turbulent kinetic energy transports in bubbly flows. (author)

  1. Metode şi tehnici experimentale pentru determinarea emisiilor provenite din materialele de construcţii

    Directory of Open Access Journals (Sweden)

    Vasilica Vasile

    2011-06-01

    Full Text Available The determination of the volatile organic compounds (VOCs from the construction materials, present in indoor environment, is a topic of great interest, because most people spend 90% of the day, at inside, there where the pollution level can be high, pollution sources, aried and long-term exposure, a risk that can seriously affect the health of the occupants, with the advent of changes in genetic structure andweakening the immune system. To minimize such risks are necessary a range of information, starting from requirements and performance levels, used in the design stage, thus facilitating the selection of building materials in terms of emission levels and continuing with the optimal solutions for energy consumption. The methods used for the determination of the levels of these compounds emitted from different building materials can be direct methods and indirect methods of detection. The article aims to present the currentstate of these methods and experimental techniques, for the knowledge of the domain, then allowing the collection of information on emission levels in the existing built environment and their otification to stakeholders, with the intention to create conditions that underpin a responsible attitude towards the design and implementation of healthy constructions.

  2. Computational and Experimental Assessment of Jets in Cross Flow (Evaluation Numerique et Experimentale des Jets dans des Courants Transversaux)

    Science.gov (United States)

    1993-11-01

    parois environnantes soit directoment , soit par l’inter- mtdiare de chocs d’interaction induits par la rencontre des a/.=0,2 jets de contr~le et de...LES to regions that are truly unsteady. I think that we are going to need hybrid methodo !ogy to try and do things from an engineering point of view

  3. Experimental data on fission and (n,xn) reactions; Donnees experimentales de fission et de reactions (n,xn)

    Energy Technology Data Exchange (ETDEWEB)

    Belier, G.; Chatillon, A.; Granier, T.; Laborie, J.M.; Laurent, B.; Ledoux, X.; Taieb, J.; Varignon, C.; Bauge, E.; Bersillon, O.; Aupiais, J.; Le Petit, G. [CEA Bruyeres-le-Chatel, 91 (France); Authier, N.; Casoli, P. [CEA Valduc, 21 - Is-sur-Tille (France)

    2011-07-15

    Investigations on neutron-induced fission of actinides and the deuteron breakup are presented. Neutron-induced fission has been studied for 10 years at the WNR (Weapons Neutron Research) neutron facility of the Los Alamos Neutron Science Center (LANSCE). Thanks to this white neutron source the evolution of the prompt fission neutron energy spectra as a function of the incident neutron energy has been characterized in a single experiment up to 200 MeV incident energy. For some isotopes the prompt neutron multiplicity has been extracted. These experimental results demonstrated the effect on the mean neutron energy of the neutron emission before scission for energies higher than the neutron binding energy. This extensive program ({sup 235}U and {sup 238}U, {sup 239}Pu, {sup 237}Np and {sup 232}Th were measured) is completed by neutron spectra measurements on the CEA 4 MV accelerator. The D(n,2n) reaction is studied both theoretically and experimentally. The cross-section was calculated for several nucleon-nucleon interactions including the AV18 interaction. It has also been measured on the CEA 7 MV tandem accelerator at incident neutron energies up to 25 MeV. Uncertainties lower than 8% between 5 and 10 MeV were obtained. In particular these experiments have extended the measured domain for cross sections. (authors)

  4. Experimental determination of thermal conductivities of dielectric thin films; Determination experimentale des conductivites thermiques de couches minces dielectriques

    Energy Technology Data Exchange (ETDEWEB)

    Scudeller, Y.; Hmina, N.; Lahmar, J.; Bardon, J.P. [Nantes Univ., 44 (France)

    1996-12-31

    This paper presents a method of measurement of thermal conductivity of sub-micron dielectric films in a direction perpendicular to the substrate. These films (oxides, nitrides, diamond..) are mainly used for the electrical insulation of semiconductor circuits and in optical treatments of high energy lasers. The principle of the method used and the experimental device are described. The results obtained with silicon oxides are discussed. (J.S.) 13 refs.

  5. Caracterización de la ovoposición del caracol Pomacea flagellata (Say, 1827 bajo condiciones experimentales

    Directory of Open Access Journals (Sweden)

    Alberto de Jesús-Navarrete

    2016-12-01

    Full Text Available Pomacea flagellata es un caracol conspicuo de zonas tropicales y subtropicales de América, que se ha consumido desde tiempos prehispánicos y actualmente es considerado sobreexplotado. Se realizó un experimento de cultivo de cuatro meses para determinar: la selección del substrato por la hembra, el tamaño de las huevas, el nivel del agua elegido para colocar la masa de huevos, el número de crías, y el tiempo de eclosión. Se utilizaron tres tinas de plástico que se llenaron con 100 L de agua, por duplicado y se colocaron tres sustratos: raíces de mangle, carrizo y tubo de PVC. Se registraron 57 huevas, 26 de ellas eclosionaron produciendo 5037 crías. Hubo más huevas en la “pared” de las tinas, donde se registraron 35 huevas, en raíces de mangle (18, en PVC 3 y en carrizo una hueva. Hubo diferencias significativas en la selección del sustrato, mientras que no se observaron diferencias significativas entre el número de huevas y las proporciones de sexos. La longitud promedio de la masa fue 32.99 ± 10.92, el ancho 16.44 ± 5.1 y grosor 8.08 ± 3.87 mm. La altura promedio de la puesta fue 15.66 ± 3.42 cm, con un tiempo medio de eclosión, de 13.30 ± 2.6 días, obteniéndose entre 94 a 301 crías por desove. Los caracoles utilizaron preferentemente las paredes de las tinas y es difícil determinar si no seleccionan sustrato para la puesta. El nivel del agua empleado es óptimo y permite que los organismos puedan colocar las masas de huevo, la producción de crías es adecuada y suficiente para iniciar programas de cultivo de producción de carne o de repoblación del medio natural.

  6. Experimental contamination of pink shrimps by caesium 137; Contamination experimentale de crevettes roses par le cesium 137

    Energy Technology Data Exchange (ETDEWEB)

    Ancellin, J.; Michon, G.; Vilquin, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1965-07-01

    The authors describe first of all the technique used for the determination of cesium 137 concentration factors in the pink shrimp (Leander Serratus Pennant). Experiments over three months have shown that the specific activity of the shrimps becomes stable between the thirtieth and the fortieth day. The concentration factors then have values between 30 and 40. These results are similar to those obtained by other authors. (authors) [French] Les auteurs decrivent tout d'abord la technique utilisee pour la determination des facteurs de concentration du Cesium 137 chez la crevette rose (Leander Serratus Pennant). Le resultat des experimentations menees pendant trois mois montre que l'activite specifique des crevettes se stabilise entre le trentieme et le quarantieme jour. Les facteurs de concentration se situent alors entre 30 et 40, Ces donnees sont comparables a celles obtenues par d'autres auteurs. (auteur)

  7. The Culture of Experimentalism in the Holy Roman Empire: Johann Christoph Sturm (1635-1703) and the Collegium Experimentale

    OpenAIRE

    Ahnert, Thomas

    2002-01-01

    From the second half of the seventeenth century systematic experimentation had increasingly come to be seen as a crucial means of producing and testing natural philosophical theories. The institutions, that are most famous for applying this experimental method, are societies such as the Royal Society in London or the Accademia del Cimento in Florence. In my paper I focus on an important example of experimentalist culture and its context in the Holy Roman Empire which has received little atten...

  8. Radioactive contamination of aquatic media and organisms; La contamination radioactive des milieux et des organismes aquatiques

    Energy Technology Data Exchange (ETDEWEB)

    Fontaine, Y. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    After a brief account of the radioactive wastes produced by peaceful or military uses of Atomic Industry, the author first describes a series of observations carried out 'in the field' on the extent of contamination in aquatic organisms with respect to that of the medium. The experimental studies are then analysed, with reference both to the radioisotope metabolism and to the factors and types of contamination of aquatic organisms by wastes from atomic industry. A precise experimental project is presented at the end of the paper, including almost 300 references. (author) [French] Apres une courte etude des dechets radioactifs produits par les utilisations pacifiques ou militaires de l'Industrie Atomique, l'auteur fait etat d'abord des observations effectuees 'sur le terrain' concernant l'extension de la contamination des organismes aquatiques en rapport avec celle du milieu. L'auteur analyse ensuite les etudes experimentales se rapportant aussi bien au metabolisme des radioisotopes qu'aux facteurs et aux modalites de la contamination des organismes aquatiques par les dechets de l'industrie atomique. Un projet de travail experimental precis est presente a la fin de cette revue qui comporte pres de 300 references bibliographiques. (auteur)

  9. African Journal of Science and Technology (AJST) ETUDE ...

    African Journals Online (AJOL)

    principaux la visualisation automatique par traitement d'images. D'où la nécessité. Figure1 : prise de vue du banc d'essai. Positionnement et mise au point de la caméra. Une bonne visualisation ainsi que des mesures précises nécessitent un positionnement soigneux et minutieux de la caméra, et la possibilité d'ajuster ces.

  10. etude socio-anthropologique de la gestion des ressources naturelles

    African Journals Online (AJOL)

    SECRETARIAT

    naturelles dont la gestion rationnelle peut constituer des atouts majeurs pour son développement durable. Le présent document fait le point des travaux initiés ..... projets de développement. Au Centre, les producteurs pratiquent une agriculture .... risque d'être châtié par celui-ci. D'ailleurs, le mode traditionnel d'accès aux.

  11. Etude descriptive de la reglementation de la biologie medicale en ...

    African Journals Online (AJOL)

    Other aspects such as biosafety benefit from a framework (UEMOA) and deserve a transposition in the national texts. Finally, it remains not only to update the existing regulations but also to propose a legal framework for the not yet regulated fields of medical biology in Côte d'Ivoire. Keywords: Medical biology, regulation, ...

  12. ETUDE DE L'INSUFFISANCE ERECTILE DANS UNE POPULATION

    African Journals Online (AJOL)

    L'INSUFFISANCE ERECTILE DANS UNE POPULATION D'HOMMES JEUNES ET SEXUELLEMENT ACTIFS. Tableau n° 2: Répartition des tares en fonction de leur prévalence dans l'échantillon. Tares Effectifs %. Hémorroïde 141 16,5%. Hypertension artérielle 40 4,7%. Ulcère gastroduodénal 51 6,0%. Cardiopathie 22 2 ...

  13. Etude thermique expérimentale des suspensions non newtoniennes ...

    African Journals Online (AJOL)

    Newtonian and pseudoplastic suspensions flowing in a horizontal pipe with variable geometry. These suspensions are composed of large hard spheres in a solution of Tylose. It helped to highlight the limits of the development of the thermal boundary ...

  14. 1 Etude thermique expérimentale des suspensions non ...

    African Journals Online (AJOL)

    FAGLA

    Experimental thermal studyof the non-newtonian suspensionsflowingin ahorizontalductwith variable geometry. In the Agri-Food industry, new products, more and more complex for researchers, are put into consumption. This paper presents the results of an experimental study of heating Non-Newtonian and pseudoplastic.

  15. ETUDE PHOTOELECTROCHIMIQUE DE COUCHES PASSIVES A LA SURFACE DU FER

    Directory of Open Access Journals (Sweden)

    F ROUINA

    2002-06-01

    Full Text Available Des études photoélectrochimiques des couches passives sur le fer pur (99,9999%, réalisées en milieu alcalin KOH 1M ou en présence du couple rédox [Fe(CN6]4-/[Fe(CN6]3-, sont présentées. La photoréactivité de ces couches vis-à-vis de l'ion [Fe(CN6]4- a montré le caractère photo-accepteur des états de surface. Les photocourants représentés suivent un modèle de Poole-Frenkel et sont modifiés par l’addition de quantité croissante de [Fe(CN6]4-.

  16. Etude des possibilites de contamination des aliments de rues au ...

    African Journals Online (AJOL)

    Ainsi, notre étude a eu pour but d'étudier les possibilités de contamination de quelques aliments de rue prélevés chez des vendeurs dans la ville de Cotonou au Bénin. Les investigations sur les lieux de vente et les résultats d'analyse microbiologique ont révélé la présence d'un risque perpétuel de contamination selon les ...

  17. Etude descriptive de la formation d'acrylamide dans quelques ...

    African Journals Online (AJOL)

    Ces risques sont plus élevés pour les frites de pomme de terre et pour les dérivés du café. L'analyse des méthodes de transformations industrielles et domestiques des aliments peut permettre de déterminer des indicateurs pour mettre en oeuvre des mesures de prévention ou de réduction du risque de formation de ...

  18. ETUDE DE LA FERTILITE FEMELLE DE CINQ CLONES CULTIVES ...

    African Journals Online (AJOL)

    USER

    source de caoutchouc naturel. C'est une espèce monoïque à allogamie chez laquelle l'auto fécondation est aussi observée (Sunderasan et al., 1994). A l'état spontané en Amazonie, la pollinisation naturelle chez l'hévéa est généralement réalisée par des insectes et parfois par le vent. Après la pollinisation de la fleur.

  19. ETUDE DILATOMETRIQUE ET SPECTROSCOPIQUE DU NANOCOMPOSITE PE + 5%NTCM

    Directory of Open Access Journals (Sweden)

    T DORBANI

    2016-06-01

    Full Text Available L’objectif de ce travail est l’étude thermodynamique et structurale du nanocomposite le polyéthylène haute densité contenant 5% de nanotube de carbone multiparois (NTCM. Les résultats dilatométriques montrent que les NTCM sont responsables de la diminution de l’anisotropie. Le pouvoir calorifique du nanocomposite PE + 5% NTCM est moins important que celui du polyéthylène pur. Le spectre infrarouge montre que l’introduction de 5% NTCM dans PE augmente la cristallinité. La spectroscopie Raman du nanomatériau étudié révèle une diminution de la concentration de défauts. Cette étude fait ressortir le rôle positif des nanotubes de carbone multiparois dans le polyéthylène haute densité.

  20. Etude Petrographique et Geochimique du Complexe Annulaire de ...

    African Journals Online (AJOL)

    The Mabounie carbonatite, dated back to 660 Ma east intrusive in the series of the metamorphic proterozoic of the Ogooue system. A fenitization zone, disposed in halo develops around carbonatitic intrusion. The zones to fenites itself remove the identification marks from the gneiss by a new development of minerals such ...

  1. Study 4: the renewable energies; Etude 4: les energies renouvelables

    Energy Technology Data Exchange (ETDEWEB)

    Dupont-Roc, G. [Total Fina, 92 - Paris La Defense (France)

    2000-07-01

    In 1986 the Brundtlandt Commission formalized the durable development concept and defined in these terms: satisfy the today needs without mortgage the future generation capacity to satisfy their own needs. This concept leads to give an interest in the development of new energies sources and in the abatement of the environmental pollution. For each following energies sources, the author takes stock of the state of the art, the technological and political stakes at an international scale: the bio-fuels, the wood energy, the photovoltaic, the solar energy and the geothermal energy. (A.L.B.)

  2. Etude des interactions entre les differents acteurs des interventions ...

    African Journals Online (AJOL)

    Les chefs de ménages ont une perception acceptable de la qualité des prestations des ASC. Seuls environ 60% des ASC ont été sélectionnés par leur communauté au cours d'une assemblée générale. Les chefs de ménages ont une connaissance acceptable des ASC et de leurs activités mais leur comportement ...

  3. Diplome d'etudes specialisees de pneumologie: appreciation de la ...

    African Journals Online (AJOL)

    Objectif: Recenser l'appréciation qu'ont les apprenants sur l'école de pneumologie de Lomé. Méthodologie: Un questionnaire anonyme a été adressé aux 13 médecins en spécialisation au cours du mois d'Août 2015. Les items portaient sur les cours théoriques et la formation pratique. Résultats: Le taux de réponse était ...

  4. Etude de proprietes insecticides et fertilisantes De l'engrais ...

    African Journals Online (AJOL)

    Ergofito defense» en culture de chou a djekanou (Côte d'Ivoire) ... Malheureusement, de nombreuses contraintes freinent le développement de cette culture. L'objectif de cette ... The results were analyzed using the SAS software version 8.2.

  5. Etude analytique d'interface dynamique aeronef-navire

    Science.gov (United States)

    Ferrier, Bernard

    This report introduces an approach for the solution of real-time aircraft/ship dynamic interface problems using ship motion filtered by helicopter stability limits. The Landing Period Designator (LPD) calculates quiescent periods using the Energy Index scale. A test plan was developed in three phases. The purpose of the first phase was to demonstrate the proof-of-concept. During the second phase, a prototype was developed and tested without the pilot in the loop at-sea. In the third phase, a full-scale system was developed and tested with the pilot in the loop at-sea. The first phase was composed of simulation, assembly and test of a pre-prototype system. This report concentrates on this phase. The simulation test program was based on three hypothesis regarding the reliability of the energy index. The energy index must distinguish between various helicopter models for the same sea and ship conditions. The rise-time must always respect an inertial delay between excitation and ship displacement. Finally, the characteristics of the index using synthetic (simulated) time history must resemble a similar result using recorded time histories (for similar conditions). Aircraft-ship rise-times vary, depending the ship characteristics, between 4 to 5.5 seconds (corvette to destroyer class ships). With more than 6,200 simulation runs of the LPD, the rise-time delays were always respected. The LPD calculated with simulated data always resembled similar conditions calculated with recorded ship motion data. A strong correlation between the LPD value and its physical significance was established early in phase 1. This prompted the US Government to award a grant for the assembly of a ship motion instrumentation system which