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Sample records for des phases spectrale

  1. Correction of spectral and temporal phases for ultra-intense lasers; Correction des phases spectrale et temporelle pour les lasers ultra-intenses

    Energy Technology Data Exchange (ETDEWEB)

    Salmon, E

    2000-12-15

    The discovery of new regimes of interaction between laser and matter requires to produce laser pulses presenting higher luminous flux density. The only solutions that allow us to reach important power (about ten peta-watts) imply the correction of non-linear effects before compressing the laser pulse so that we do not transfer the phase modulation to the amplitude modulation. The aim of this work is the correction of the spectral phase through the modulation of the temporal phase. The first chapter is dedicated to the review of the physical phenomena involved in the interaction of ultra-intense laser pulse with matter. The peta-watt laser operating on the LIL (integrated laser line), the prototype line of the Megajoule Laser, is described in the second chapter. The third chapter presents the method used and optimized for getting an absolute measurement of the spectral phase in our experimental configuration. The fourth chapter details the analogy existing between the spatial domain and the temporal domain particularly between diffraction and dispersion. This analogy has allowed us to benefit from the knowledge cumulated in the spatial domain, particularly the treatment of the aberrations and their impact on the focal spot and to use it in the temporal domain. The principle of the phase correction is exposed in the fifth chapter. We have formalized the correspondence of the phase modulation between temporal domain and the spectral domain for strongly stretched pulses. In this way a modulation of the temporal phase is turned into a modulation of the spectral phase. All the measurements concerning phases and modulation spectral phase correction are presented in the sixth chapter. In the last chapter we propose an extension of the temporal phase correction by correcting non-linear effects directly in the temporal phase. This correction will improve the performances of the peta-watt laser. Numerical simulations show that the temporal phase correction can lead to a

  2. Architecture, des normes et des systèmes d'information libres, phase ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Architecture, des normes et des systèmes d'information libres, phase II (OASIS II) - Renforcement des capacités dans l'ensemble de l'Afrique. Sur presque tout le continent africain, la prestation des services de santé est limitée en raison des maigres ressources disponibles et de la charge de morbidité de plus en plus ...

  3. Spectral content of seismic movements produced by underground nuclear explosions; Contenu spectral des mouvements seismiques dus aux explosions nucleaires souterraines

    Energy Technology Data Exchange (ETDEWEB)

    Albaret, A; Duclaux, F [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1969-07-01

    After a summary of available data, both theoretical and experimental, concerning the spectral content of seismic movements, a description is given of the experiments carried out during the French nuclear explosions in the Sahara, and of the results obtained on the volume waves. A comparison is then made with certain American results. A new method is described for studying the amplitude spectra; it has made it possible to show that the amount of low frequencies in the spectrum increases with the power of the explosion, and decreases with the distance to the zero point and with the filtering effect of the weathered zone. A calculation is then made of the low cut-off ground filter, this giving a better representation of the initial seismic phenomenon. (authors) [French] Apres avoir resume les connaissances disponibles, aussi bien theoriques qu'experimentales, sur le contenu spectral des mouvements seismiques, on decrit les experiences effectuees a l'occasion des explosions nucleaires francaises du Sahara et les resultats obtenus sur les ondes de volume. Puis on les compare avec certains resultats americains. On decrit une nouvelle methode d'etude des spectres d'amplitudes qui montre que le spectre est d'autant plus riche en basses frequences que la puissance de l'explosion est grande, que la distance au point zero est faible et qu'il est moins filtre par la zone alteree superficielle. Puis on calcule le filtre terrain coupe-bas qui permet de donner une representation plus fidele du phenomene seismique initial. (auteurs)

  4. Phase spectral composition of wind generated ocean surface waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    A study of the composition of the phase spectra of wind generated ocean surface waves is carried out using wave records collected employing a ship borne wave recorder. It is found that the raw phase spectral estimates could be fitted by the Uniform...

  5. Phase coherence and Rabi frequency induced ultranarrow spectral line

    International Nuclear Information System (INIS)

    Dutta, Bibhas Kumar; Panchadhyayee, Pradipta; Mahapatra, Prasanta Kumar

    2012-01-01

    A scheme is proposed to achieve ultranarrow spectral line in the fluorescence spectrum of a lifetime broadened multilevel phase-coherent atom. It is shown that for weak-field coupling, ultranarrow spectral feature in the fluorescence spectrum can be generated by controlling the values of the Rabi frequencies involved in the coherent mechanism of the system. For fixed values of the Rabi frequencies in the weak-field limit, ultranarrow feature appears in the spectrum through the adjustment of the relative phase of the coherent fields. The results highlight that, larger the values of the decay rates associated with the field-driven channels, more pronounced is the phenomenon of narrowing in the spectrum.

  6. Spectral decomposition of single-tone-driven quantum phase modulation

    International Nuclear Information System (INIS)

    Capmany, Jose; Fernandez-Pousa, Carlos R

    2011-01-01

    Electro-optic phase modulators driven by a single radio-frequency tone Ω can be described at the quantum level as scattering devices where input single-mode radiation undergoes energy changes in multiples of ℎΩ. In this paper, we study the spectral representation of the unitary, multimode scattering operator describing these devices. The eigenvalue equation, phase modulation being a process preserving the photon number, is solved at each subspace with definite number of photons. In the one-photon subspace F 1 , the problem is equivalent to the computation of the continuous spectrum of the Susskind-Glogower cosine operator of the harmonic oscillator. Using this analogy, the spectral decomposition in F 1 is constructed and shown to be equivalent to the usual Fock-space representation. The result is then generalized to arbitrary N-photon subspaces, where eigenvectors are symmetrized combinations of N one-photon eigenvectors and the continuous spectrum spans the entire unit circle. Approximate normalizable one-photon eigenstates are constructed in terms of London phase states truncated to optical bands. Finally, we show that synchronous ultrashort pulse trains represent classical field configurations with the same structure as these approximate eigenstates, and that they can be considered as approximate eigenvectors of the classical formulation of phase modulation.

  7. Spectral decomposition of single-tone-driven quantum phase modulation

    Energy Technology Data Exchange (ETDEWEB)

    Capmany, Jose [ITEAM Research Institute, Univ. Politecnica de Valencia, 46022 Valencia (Spain); Fernandez-Pousa, Carlos R, E-mail: c.pousa@umh.es [Signal Theory and Communications, Department of Physics and Computer Science, Univ. Miguel Hernandez, 03202 Elche (Spain)

    2011-02-14

    Electro-optic phase modulators driven by a single radio-frequency tone {Omega} can be described at the quantum level as scattering devices where input single-mode radiation undergoes energy changes in multiples of {h_bar}{Omega}. In this paper, we study the spectral representation of the unitary, multimode scattering operator describing these devices. The eigenvalue equation, phase modulation being a process preserving the photon number, is solved at each subspace with definite number of photons. In the one-photon subspace F{sub 1}, the problem is equivalent to the computation of the continuous spectrum of the Susskind-Glogower cosine operator of the harmonic oscillator. Using this analogy, the spectral decomposition in F{sub 1} is constructed and shown to be equivalent to the usual Fock-space representation. The result is then generalized to arbitrary N-photon subspaces, where eigenvectors are symmetrized combinations of N one-photon eigenvectors and the continuous spectrum spans the entire unit circle. Approximate normalizable one-photon eigenstates are constructed in terms of London phase states truncated to optical bands. Finally, we show that synchronous ultrashort pulse trains represent classical field configurations with the same structure as these approximate eigenstates, and that they can be considered as approximate eigenvectors of the classical formulation of phase modulation.

  8. Heterodyne detection using spectral line pairing for spectral phase encoding optical code division multiple access and dynamic dispersion compensation.

    Science.gov (United States)

    Yang, Yi; Foster, Mark; Khurgin, Jacob B; Cooper, A Brinton

    2012-07-30

    A novel coherent optical code-division multiple access (OCDMA) scheme is proposed that uses spectral line pairing to generate signals suitable for heterodyne decoding. Both signal and local reference are transmitted via a single optical fiber and a simple balanced receiver performs sourceless heterodyne detection, canceling speckle noise and multiple-access interference (MAI). To validate the idea, a 16 user fully loaded phase encoded system is simulated. Effects of fiber dispersion on system performance are studied as well. Both second and third order dispersion management is achieved by using a spectral phase encoder to adjust phase shifts of spectral components at the optical network unit (ONU).

  9. Multi-Configuration Matched Spectral Filter Core, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — OPTRA proposes an open-architecture spectral gas sensor based on compressive sensing concepts employed for both spatial and spectral domains. Our matched spectral...

  10. Spectral Matrix Filtering Applied to Vsp Processing Application du filtrage matriciel au traitement des profils sismiques verticaux

    Directory of Open Access Journals (Sweden)

    Glangeaud F.

    2006-11-01

    données et de séparer ces signaux. Nous montrons que les signaux peuvent être automatiquement séparés sans connaissance a priori sur leurs vitesses apparentes, en fonction du produit scalaire (calculé dans le domaine fréquentiel et de l'amplitude relative des signaux. Nous montrons des exemples d'application sur des données de sismique de puits. Le filtrage matriciel est effectué dans le domaine fréquentiel en utilisant la matrice spectrale construite à l'aide des intercorrélations des différents enregistrements constituant les données à traiter. Les méthodes d'estimation de la matrice spectrale sont des méthodes de moyenne : moyenne en fréquence (méthode du périodogramme lissé et/ou moyenne en distance (lissage réalisé le long des diagonales de la matrice spectrale. Le lissage en fréquence est obtenu par l'intermédiaire d'une fonction de pondération (par exemple fenêtre de Hanning élevée à une puissance donnée appliquée à chaque corrélation. Les moyennes sont utilisées pour décorréler les signaux et de ce fait favoriser la séparation. Une fois correctement estimée, la matrice spectrale est diagonalisée sur toutes les fréquences du spectre moyenné, et décomposée selon ses vecteurs propres qui sont orthogonaux entre eux et normalisés. Chaque vecteur propre a une valeur propre associée qui représente la répartition d'énergie en fonction de la fréquence du modèle lié au vecteur propre. Le filtrage est réalisé par projection des données sur les différents vecteurs propres issus de la matrice spectrale. Il est à noter cependant que la séparation des différents signaux (projection sur vecteur propre n'est réalisée en terme d'indicatrice sismique que si les événements sismiques sont naturellement orthogonaux et alignés sur les vecteurs propres. Glangeaud et al (1989 ont étudié l'influence des amplitudes relatives et du produit scalaire de deux ondes. Si la vitesse apparente d'une onde est connue, cette derni

  11. Fine structure and spectral index measurements in natural uranium - graphite lattices; Mesures fines dans des reseaux a graphite

    Energy Technology Data Exchange (ETDEWEB)

    Cogne, F; Journet, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The experiments described in this report have been carried out for the most part in the critical facility MARIUS, and a few during the start up of the EDF-1 power reactor. The first part deals with the fine structure measurements made in various lattices and with their analysis. Integration over the neutron spectrum of the mono-kinetic disadvantage factor derived by the A.B.H method yields results in good agreement with the experiments. The second part deals with spectral indexes measurements (Pu/U, In/Mn) made at room temperature in MARIUS. Comparison are made of experiments with calculations using various thermalization models. Experiments carried out at higher temperatures in EDF-1 are also described. (authors) [French] Les mesures decrites dans ce rapport ont ete faites pour la plupart dans l'empilement critique MARIUS sur des reseaux a graphite-uranium naturel. Une premiere partie traite des mesures de structure fine faites dans differents reseaux et de leur interpretation. On montre en particulier qu'une integration sur le spectre d'un calcul monocinetique type A.B.H. rend bien compte des experiences. Dans une deuxieme partie, on donne les resultats de mesures d'indices de spectre Pu/U et In/Mn faites sur des reseaux froids a MARIUS et leur comparaison avec les differents modeles de calculs de thermalisation. On donne egalement les resultats de quelques mesures en temperature effectuees lors du demarrage du reacteur EDF-1. (auteurs)

  12. Quelques phases granitiques intrusives dans le Massif des Trois Seigneurs

    NARCIS (Netherlands)

    Nieuwenhuys, W.H.

    1956-01-01

    Pendant les étés de 1953, 1954 et 1955 j’ai effectué des travaux de terrain dans le Massif des Trois Seigneurs, Pyrénées orientales, sous la direction du Professeur L.U. de Sitter. Ces travaux de terrain comprennent entre autres le levé d’une carte géologique de la partie centrale et Sud-Ouest de ce

  13. Time domain spectral phase encoding/DPSK data modulation using single phase modulator for OCDMA application.

    Science.gov (United States)

    Wang, Xu; Gao, Zhensen; Kataoka, Nobuyuki; Wada, Naoya

    2010-05-10

    A novel scheme using single phase modulator for simultaneous time domain spectral phase encoding (SPE) signal generation and DPSK data modulation is proposed and experimentally demonstrated. Array- Waveguide-Grating and Variable-Bandwidth-Spectrum-Shaper based devices can be used for decoding the signal directly in spectral domain. The effects of fiber dispersion, light pulse width and timing error on the coding performance have been investigated by simulation and verified in experiment. In the experiment, SPE signal with 8-chip, 20GHz/chip optical code patterns has been generated and modulated with 2.5 Gbps DPSK data using single modulator. Transmission of the 2.5 Gbps data over 34km fiber with BEROCDMA) and secure optical communication applications. (c) 2010 Optical Society of America.

  14. Theoretical profiles of the spectral lines of the hydrogen atom; Profils theoriques des raies spectrales de l'atome d'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, H; Herman, L [Universite de la Sorbonne, Lab. de Recherche Physique, 75 - Paris (France); Drawin, H W [Commissariat a l' Energie Atomique, Fontenay-aux-Roses, Association Euratom-CEA, Groupe de Recherches sur la Fusion Controlee (France). Centre d' Etudes Nucleaires

    1965-07-01

    The line-broadening problem of the hydrogen lines has been formulated in the quasistatic approximation as far as the ions are concerned, and in the classical path approximation as far as the broadening due to collisions with electrons is concerned. These electrons interfere in different numerical results only by the self-correlation function of the fluctuating electrical field strength created at each point in the plasma. The Lewis correction has been applied, but using the whole velocity distribution function of the electrons. The formula which represents the usual impact profile, valid only for frequencies much smaller than the plasma frequency, has been extended using another formula which will be valid up to the neighbourhood of that spectral region where the quasi-static approximation begins to be valid also for the electrons. As an example, the line profile of Ly {alpha} is given by some graphs for T = 10{sup 4} deg. K and electron densities N = 10{sup 17} cm{sup -3} and N = 10{sup 18}cm{sup -3}. (authors) [French] Le probleme d'elargissement des raies de l'atome H est formule dans l'approximation quasi-statique en ce qui concerne les ions et dans l'approximation du chemin classique en ce qui concerne les electrons. Ceux-ci interviennent dans differents resultats uniquement par la fonction auto-correlation du champ electrique fluctuant qu'ils creent en chaque point du plasma. La correction de Lewis a ete appliquee mais en tenant compte de la distribution des vitesses electroniques. La formule donnant les profils d'impact habituels, valable seulement pour des frequences tres inferieures a la frequence du plasma, est ainsi prolongee de maniere continue par une autre formule, valable jusqu'au voisinage de la region spectrale ou l'approximation quasistatique commence a etre egalement justifiee pour les electrons. A titre d'illustration on represente graphiquement le profil de la raie Ly {alpha} pour T = 10{sup 4} deg. K et des densites electroniques de N = 10{sup

  15. Multi-Configuration Matched Spectral Filter Core, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — OPTRA proposes the development of a modular, reconfigurable matched spectral filter (RMSF) spectrometer for the monitoring of greenhouse and volcanic gases. The...

  16. Improved phase sensitivity in spectral domain phase microscopy using line-field illumination and self phase-referencing

    Science.gov (United States)

    Yaqoob, Zahid; Choi, Wonshik; Oh, Seungeun; Lue, Niyom; Park, Yongkeun; Fang-Yen, Christopher; Dasari, Ramachandra R.; Badizadegan, Kamran; Feld, Michael S.

    2010-01-01

    We report a quantitative phase microscope based on spectral domain optical coherence tomography and line-field illumination. The line illumination allows self phase-referencing method to reject common-mode phase noise. The quantitative phase microscope also features a separate reference arm, permitting the use of high numerical aperture (NA > 1) microscope objectives for high resolution phase measurement at multiple points along the line of illumination. We demonstrate that the path-length sensitivity of the instrument can be as good as 41 pm/Hz, which makes it suitable for nanometer scale study of cell motility. We present the detection of natural motions of cell surface and two-dimensional surface profiling of a HeLa cell. PMID:19550464

  17. Slow-Light-Enhanced Spectral Interferometers, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We proposoe a research program aimed at developing spectral interferometers with dramatically enhanced performance. A key aspect of our approach is to place a highly...

  18. Self-phase-modulation induced spectral broadening in silicon waveguides

    Science.gov (United States)

    Boyraz, Ozdal; Indukuri, Tejaswi; Jalali, Bahram

    2004-03-01

    The prospect for generating supercontinuum pulses on a silicon chip is studied. Using ~4ps optical pulses with 2.2GW/cm2 peak power, a 2 fold spectral broadening is obtained. Theoretical calculations, that include the effect of two-photon-absorption, indicate up to 5 times spectral broadening is achievable at 10x higher peak powers. Representing a nonlinear loss mechanism at high intensities, TPA limits the maximum optical bandwidth that can be generated.

  19. Auditory sensitivity to spectral modulation phase reversal as a function of modulation depth.

    Science.gov (United States)

    Buss, Emily; Grose, John

    2018-01-01

    The present study evaluated auditory sensitivity to spectral modulation by determining the modulation depth required to detect modulation phase reversal. This approach may be preferable to spectral modulation detection with a spectrally flat standard, since listeners appear unable to perform the task based on the detection of temporal modulation. While phase reversal thresholds are often evaluated by holding modulation depth constant and adjusting modulation rate, holding rate constant and adjusting modulation depth supports rate-specific assessment of modulation processing. Stimuli were pink noise samples, filtered into seven octave-wide bands (0.125-8 kHz) and spectrally modulated in dB. Experiment 1 measured performance as a function of modulation depth to determine appropriate units for adaptive threshold estimation. Experiment 2 compared thresholds in dB for modulation detection with a flat standard and modulation phase reversal; results supported the idea that temporal cues were available at high rates for the former but not the latter. Experiment 3 evaluated spectral modulation phase reversal thresholds for modulation that was restricted to either one or two neighboring bands. Flanking bands of unmodulated noise had a larger detrimental effect on one-band than two-band targets. Thresholds for high-rate modulation improved with increasing carrier frequency up to 2 kHz, whereas low-rate modulation appeared more consistent across frequency, particularly in the two-band condition. Experiment 4 measured spectral weights for spectral modulation phase reversal detection and found higher weights for bands in the spectral center of the stimulus than for the lowest (0.125 kHz) or highest (8 kHz) band. Experiment 5 compared performance for highly practiced and relatively naïve listeners, and found weak evidence of a larger practice effect at high than low spectral modulation rates. These results provide preliminary data for a task that may provide a better estimate of

  20. Selective suppression of high-order harmonics within phase-matched spectral regions.

    Science.gov (United States)

    Lerner, Gavriel; Diskin, Tzvi; Neufeld, Ofer; Kfir, Ofer; Cohen, Oren

    2017-04-01

    Phase matching in high-harmonic generation leads to enhancement of multiple harmonics. It is sometimes desired to control the spectral structure within the phase-matched spectral region. We propose a scheme for selective suppression of high-order harmonics within the phase-matched spectral region while weakly influencing the other harmonics. The method is based on addition of phase-mismatched segments within a phase-matched medium. We demonstrate the method numerically in two examples. First, we show that one phase-mismatched segment can significantly suppress harmonic orders 9, 15, and 21. Second, we show that two phase-mismatched segments can efficiently suppress circularly polarized harmonics with one helicity over the other when driven by a bi-circular field. The new method may be useful for various applications, including the generation of highly helical bright attosecond pulses.

  1. Phase locking and spectral linewidth of a two-mode terahertz quantum cascade laser

    NARCIS (Netherlands)

    Baryshev, A.; Hovenier, J. N.; Adam, A. J. L.; Kašalynas, I.; Gao, J. R.; Klaassen, T. O.; Williams, B. S.; Kumar, S.; Hu, Q.; Reno, J. L.

    2006-01-01

    We have studied the phase locking and spectral linewidth of an ˜2.7THz quantum cascade laser by mixing its two lateral lasing modes. The beat signal at about 8GHz is compared with a microwave reference by applying conventional phase lock loop circuitry with feedback to the laser bias current. Phase

  2. Bandwidth Controllable Tunable Filter for Hyper-/Multi-Spectral Imager, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I proposal introduces a fast speed bandwidth controllable tunable filter for hyper-/multi-spectral (HS/MS) imagers. It dynamically passes a variable...

  3. Thermal Infrared Spectra of Microcrystalline Sedimentary Phases: Effects of Natural Surface Roughness on Spectral Feature Shape

    Science.gov (United States)

    Hardgrove, C.; Rogers, A. D.

    2012-03-01

    Thermal infrared spectral features of common microcrystalline phases (chert, alabaster, micrite) are presented. Spectra are sensitive to mineralogy and micron-scale (~1-25 µm) surface roughness. Roughness is on the scale of the average crystal size.

  4. Quantifying Neural Oscillatory Synchronization: A Comparison between Spectral Coherence and Phase-Locking Value Approaches

    Science.gov (United States)

    Lowet, Eric; Roberts, Mark J.; Bonizzi, Pietro; Karel, Joël; De Weerd, Peter

    2016-01-01

    Synchronization or phase-locking between oscillating neuronal groups is considered to be important for coordination of information among cortical networks. Spectral coherence is a commonly used approach to quantify phase locking between neural signals. We systematically explored the validity of spectral coherence measures for quantifying synchronization among neural oscillators. To that aim, we simulated coupled oscillatory signals that exhibited synchronization dynamics using an abstract phase-oscillator model as well as interacting gamma-generating spiking neural networks. We found that, within a large parameter range, the spectral coherence measure deviated substantially from the expected phase-locking. Moreover, spectral coherence did not converge to the expected value with increasing signal-to-noise ratio. We found that spectral coherence particularly failed when oscillators were in the partially (intermittent) synchronized state, which we expect to be the most likely state for neural synchronization. The failure was due to the fast frequency and amplitude changes induced by synchronization forces. We then investigated whether spectral coherence reflected the information flow among networks measured by transfer entropy (TE) of spike trains. We found that spectral coherence failed to robustly reflect changes in synchrony-mediated information flow between neural networks in many instances. As an alternative approach we explored a phase-locking value (PLV) method based on the reconstruction of the instantaneous phase. As one approach for reconstructing instantaneous phase, we used the Hilbert Transform (HT) preceded by Singular Spectrum Decomposition (SSD) of the signal. PLV estimates have broad applicability as they do not rely on stationarity, and, unlike spectral coherence, they enable more accurate estimations of oscillatory synchronization across a wide range of different synchronization regimes, and better tracking of synchronization-mediated information

  5. Quantifying Neural Oscillatory Synchronization: A Comparison between Spectral Coherence and Phase-Locking Value Approaches.

    Directory of Open Access Journals (Sweden)

    Eric Lowet

    Full Text Available Synchronization or phase-locking between oscillating neuronal groups is considered to be important for coordination of information among cortical networks. Spectral coherence is a commonly used approach to quantify phase locking between neural signals. We systematically explored the validity of spectral coherence measures for quantifying synchronization among neural oscillators. To that aim, we simulated coupled oscillatory signals that exhibited synchronization dynamics using an abstract phase-oscillator model as well as interacting gamma-generating spiking neural networks. We found that, within a large parameter range, the spectral coherence measure deviated substantially from the expected phase-locking. Moreover, spectral coherence did not converge to the expected value with increasing signal-to-noise ratio. We found that spectral coherence particularly failed when oscillators were in the partially (intermittent synchronized state, which we expect to be the most likely state for neural synchronization. The failure was due to the fast frequency and amplitude changes induced by synchronization forces. We then investigated whether spectral coherence reflected the information flow among networks measured by transfer entropy (TE of spike trains. We found that spectral coherence failed to robustly reflect changes in synchrony-mediated information flow between neural networks in many instances. As an alternative approach we explored a phase-locking value (PLV method based on the reconstruction of the instantaneous phase. As one approach for reconstructing instantaneous phase, we used the Hilbert Transform (HT preceded by Singular Spectrum Decomposition (SSD of the signal. PLV estimates have broad applicability as they do not rely on stationarity, and, unlike spectral coherence, they enable more accurate estimations of oscillatory synchronization across a wide range of different synchronization regimes, and better tracking of synchronization

  6. Spectral Phase Modulation and chirped pulse amplification in High Gain Harmonic Generation

    CERN Document Server

    Wu, Zilu; Krinsky, Sam; Loos, Henrik; Murphy, James; Shaftan, Timur; Sheehy, Brian; Shen, Yuzhen; Wang, Xijie; Yu Li Hua

    2004-01-01

    High Gain Harmonic Generation (HGHG), because it produces longitudinally coherent pulses derived from a coherent seed, presents remarkable possibilities for manipulating FEL pulses. If spectral phase modulation imposed on the seed modulates the spectral phase of the HGHG in a deterministic fashion, then chirped pulse amplification, pulse shaping, and coherent control experiments at short wavelengths become possible. In addition, the details of the transfer function will likely depend on electron beam and radiator dynamics and so prove to be a useful tool for studying these. Using the DUVFEL at the National Synchrotron Light Source at Brookhaven National Laboratory, we present spectral phase analyses of both coherent HGHG and incoherent SASE ultraviolet FEL radiation, applying Spectral Interferometry for Direct Electric Field Reconstruction (SPIDER), and assess the potential for employing compression and shaping techniques.

  7. Phase locking and spectral linewidth of a two-mode terahertz quantum cascade laser

    NARCIS (Netherlands)

    Baryshev, A.; Hovenier, J.N.; Adam, A.J.L.; Kašalynas, I.; Gao, J.R.; Klaassen, T.O.; Williams, B.S.; Kumar, S.; Hu, Q.; Reno, J.L.

    2006-01-01

    We have studied the phase locking and spectral linewidth of an ? 2.7?THz quantum cascade laser by mixing its two lateral lasing modes. The beat signal at about 8?GHz is compared with a microwave reference by applying conventional phase lock loop circuitry with feedback to the laser bias current.

  8. Phase extracting algorithms analysis in the white-light spectral interferometry

    Science.gov (United States)

    Guo, Tong; Li, Bingtong; Li, Minghui; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2018-01-01

    As an optical testing method, white-light spectral interferometry has the characteristics of non-contact, high precision. The phase information can be obtained by analyzing the spectral interference signal of the tested sample, and then the absolute distance is calculated. Fourier transform method, temporal phase-shifting method, spatial phase-shifting method and envelope method can be used to extract the phase information of the spectral interference signal. In this paper, the performance of four methods to extract phase information is simulated and analyzed by using the ideal spectral interference signal. It turns out that temporal phase-shifting method has the performance of high precision, the results of Fourier transform method and envelop method are distorted at the edge of the signal, and spatial phase-shifting method has the worst precision. Adding different levels of white noise to the ideal signal, temporal phase-shifting method is most accurate, while Fourier transform method and envelope method are relatively poor. Finally, the absolute distance measurement experiment is carried out on the constructed test system, and the results are consistent with the simulation ones.

  9. Séparation des ondes P et S à l'aide de la matrice spectrale avec informations à priori The Separation of P and S Waves Using the Spectral Matrix with a Priori Information

    Directory of Open Access Journals (Sweden)

    Mari J. L.

    2006-11-01

    Full Text Available Classiquement, la technique de filtrage utilisant la matrice spectrale proposée par Mermoz ne permet une séparation automatique des ondes au sens des indicatrices sismiques que dans certains cas particuliers, à savoir lorsque les ondes à séparer sont naturellement alignées sur les vecteurs propres de la matrice spectrale. Dans les autres cas, nous montrons que l'introduction d'information a priori sur la vitesse apparente de quelques ondes et une limitation de la durée temporelle de ces dernières permettent d'estimer leurs vecteurs d'ondes. L'utilisation de ces vecteurs et une technique de projection au sens des moindres carrés conduit à une extraction optimale de ces ondes, sans dégrader les autres ondes. La technique de filtrage proposée a été appliquée sur des données sismiques de type PSV (profil sismique vertical déporté. Le PSV a été enregistré dans un puits entre les cotes 1050 m et 1755 m; la source est déportée de 654 m par rapport à la tête de puits. L'outil utilisé est un géophone de puits à trois composantes. Le puits traverse une structure géologique complexe. Le traitement réalisé a mis en évidence des réflexions sismiques d'ondes de compression et de cisaillement, associées à des marqueurs fortement pentés (10 à 25°. Après estimation des champs de vitesse et des pendages à l'aide d'abaques, la migration en profondeur des horizons temps pointés a permis d'obtenir un modèle structural faillé. Detailed structural analysis can be achieved by using 3-component vertical seismic profiling method which gives structural information at several hundred meters from the wellhead. The use of an offset VSP on the Auzance structure has led to obtain a structural model composed by faulted dipping reflectors. This is due to the robust nature of the wave separation method which is based on the spectral matrix and uses an a priori information. This method preserves the true amplitude and the local apparent

  10. Contribution to the study of the thermodynamic properties of solutions using their phase diagrams (1961); Contribution au calcul des proprietes thermodynamiques des solutions a partir des diagrammes de phases (1961)

    Energy Technology Data Exchange (ETDEWEB)

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

    1961-10-15

    The thermodynamic study of the behaviour of solutions is of great interest in applied metallurgical problems, since the use of physical phenomena (solubility or volatility, for example) makes it possible to effect chemical reactions which, would not take place if the products formed did not mix. It is interesting to be able to predict this behaviour, at least for binary systems, using a knowledge of the phase diagrams. After showing the theoretical impossibility of resolving this problem without further data, an attempt is made to show what can be calculated from a knowledge of the phase diagrams: on the one hand it is possible to study the coherence between different types of data (calorimetric or equilibrium); on the other hand can be calculated the 'model' parameters, whether they be empirical, or statistically derived, and their validity can be checked. (author) [French] L'etude thermodynamique du comportement des solutions presente un grand interet dans les problemes de metallurgie appliquee puisque l'emploi de phenomenes physiques (solubilite ou volatilisation par exemple) permet de realiser des reactions chimiques qui seraient irrealisables si les produits formes ne se melangeaient pas. Il semble tres interessant de pouvoir prevoir ce comportement, tout au moins dans le cas de systemes binaires, a partir de la connaissance des diagrammes de phases. Apres avoir montre l'impossibilite theorique de resoudre ce probleme sans autres donnees, on essaie de voir ce que permet de calculer la connaissance des diagrammes de phases: d'une part, on peut etudier la coherenc entre divers types de donnees (calorimetrique ou d'equilibre); d'autre-part, on peut calculer les parametres de 'modeles', qu'ils soient empiriques ou a base statistique, et verifier leur validite. (auteur)

  11. Phase control of higher spectral components in the presence of a static electric field

    International Nuclear Information System (INIS)

    Zhang Chaojin; Yang Weifeng; Song Xiaohong; Xu Zhizhan

    2009-01-01

    We investigate the higher spectral component generations driven by a few-cycle laser pulse in a dense medium when a static electric field is present. Our results show that, when assisted by a static electric field, the dependence of the transmitted laser spectrum on the carrier-envelope phase (CEP) is significantly increased. Continuum and distinct peaks can be achieved by controlling the CEP of the few-cycle ultrashort laser pulse. Such a strong variation is due to the fact that the presence of the static electric field modifies the waveform of the combined electric field, which further affects the spectral distribution of the generated higher spectral components.

  12. Analysis of the corium phases by X-ray diffraction; Analyses des phases du corium par diffraction des rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Trillon, G

    2004-07-01

    In the framework of the severe accidents R and D studies led by CEA, the better knowledge of the corium behaviour, corium coming from the melting of a nuclear reactor, are fundamental stakes in order to master this kind of accident. Among the available physical properties of the corium, the nature of the final crystalline compounds which have been made during the, cooling gives information about its solidification and its stabilisation. X-Rays Diffraction is the reference method used in order to characterize the corium coming from the different facilities of the European platform PLINIUS of CEA-Cadarache. This work presents the scientific approach that has been followed in order to obtain information both qualitative and quantitative on corium, using X-Rays Diffraction. For instance, a specific method for identifying U{sub 1-x}Zr{sub x}O{sub 2} solid solutions has been developed, and the validity of quantitative analysis of corium crystalline phases using the Rietveld method (with an internal standard), has been tested. This last method has also permitted semi-quantitative measurements of amorphous phases within corium. For these studies, analysis of prototypical corium has been conducted on samples coming from the experiences led on the different facilities of the PLINIUS platform. These analysis allowed for the first time to obtain quantitative data of the corium crystalline phases in order to validate thermodynamic databases and has been used to estimate the thereto-physical properties of the corium. New information on crystalline phases of corium has also been found, especially for the UO{sub 2}-ZrO{sub 2} pseudo binary system. (author)

  13. Étude des perturbations du sommeil dans le trouble bipolaire en phase euthymique

    OpenAIRE

    St-Amand, Julie

    2012-01-01

    L'objectif de la présente étude est de décrire la nature et la sévérité des difficultés de sommeil et les problèmes de fonctionnement diurne des individus qui ont un trouble bipolaire lorsqu'ils sont dans la phase euthymique de la maladie. Quatorze participants avec un trouble bipolaire sont comparés à 13 participants avec insomnie primaire et à 13 individus sans problème de santé mentale et sans insomnie sur différents paramètres du sommeil et du fonctionnement diurne provenant de l'agenda d...

  14. Spectrally resolved modal characteristics of leaky-wave-coupled quantum cascade phase-locked laser arrays

    Science.gov (United States)

    Sigler, Chris; Gibson, Ricky; Boyle, Colin; Kirch, Jeremy D.; Lindberg, Donald; Earles, Thomas; Botez, Dan; Mawst, Luke J.; Bedford, Robert

    2018-01-01

    The modal characteristics of nonresonant five-element phase-locked arrays of 4.7-μm emitting quantum cascade lasers (QCLs) have been studied using spectrally resolved near- and far-field measurements and correlated with results of device simulation. Devices are fabricated by a two-step metal-organic chemical vapor deposition process and operate predominantly in an in-phase array mode near threshold, although become multimode at higher drive levels. The wide spectral bandwidth of the QCL's core region is found to be a factor in promoting multispatial-mode operation at high drive levels above threshold. An optimized resonant-array design is identified to allow sole in-phase array-mode operation to high drive levels above threshold, and indicates that for phase-locked laser arrays full spatial coherence to high output powers does not require full temporal coherence.

  15. Determination of the variation of mercury isotope concentration based on spectral-phase effects

    International Nuclear Information System (INIS)

    Ganeev, A.A.; Man', D.D.; Turkin, Yu.I.

    1988-01-01

    A method of isotopic atomic-absorption analysis, based on spectral-phase effects in which there is no need to use several sources of radiation with pure isotopes of the analyte element, was developed. The method made it possible to simplify the analysis and to determine the variation of the concentration of mercury isotopes from one deposit to another with an accuracy several times higher that of traditional methods of spectral isotopic analysis. The method was tested on mercury 198 and mercury 202. The isotopic analyzer is diagramed and described. The mechanism of spectral-phase effects was determined by the difference in effective photon lifetimes, corresponding to different components of the hyperfine structure of the resonance line of mercury at 254 nm

  16. Spectral phase shift and residual angular dispersion of an accousto-optic programme dispersive filter

    International Nuclear Information System (INIS)

    Boerzsoenyi, A.; Meroe, M.

    2010-01-01

    Complete text of publication follows. There is an increasing demand for active and precise dispersion control of ultrashort laser pulses. In chirped pulse amplification (CPA) laser systems, the dispersion of the optical elements of the laser has to be compensated at least to the fourth order to obtain high temporal contrast compressed pulses. Nowadays the most convenient device for active and programmable control of spectral phase and amplitude of broadband laser pulses is the acousto-optic programmable dispersive filter (AOPDF), claimed to be able to adjust the spectral phase up to the fourth order. Although it has been widely used, surprisingly enough there has been only a single, low resolution measurement reported on the accuracy of the induced spectral phase shift of the device. In our paper we report on the first systematic experiment aiming at the precise characterization of an AOPDF device. In the experiment the spectral phase shift of the AOPDF device was measured by spectrally and spatially resolved interferometry, which is especially powerful tool to determine small dispersion values with high accuracy. Besides the spectral phase dispersion, we measured both the propagation direction angular dispersion (PDAD) and the phase front angular dispersion (PhFAD). Although the two quantities are equal for plane waves, there may be noticeable difference for Gaussian pulses. PDAD was determined simply by focusing the beam on the slit of an imaging spectrograph, while PhFAD was measured by the use of an inverted Mach-Zehnder interferometer and an imaging spectrograph. In the measurements, the spectral phase shift and both types of angular dispersion have been recorded upon the systematic change of all the accessible functions of the acousto-optic programmable dispersive filter. The measured values of group delay dispersion (GDD) and third order dispersion (TOD) have been found to agree with the preset values within the error of the measurement (1 fs 2 and 10 fs 3

  17. Fractionation of Hydrocarbons Between Oil and Gas Phases Fractionnement des hydrocarbures entre les phases huile et gaz

    Directory of Open Access Journals (Sweden)

    Ruffier-Meray V.

    2006-12-01

    Full Text Available The investigation of hydrocarbon fractionation between oil and gas phases is of interest for several purposes in reservoir exploitation. In reservoir geochemistry, the evolution of light hydrocarbon fractions of oils may explain some migration phenomena. In gas injection projects, the preferred dissolution of some components in gas may alter the composition as well as the properties of the oil. Underground gas storage in depleted oil reservoirs may also be concerned by these problems. Results of several IFP studies are described here to illustrate and to quantify the phenomenon. Two of them, using real reservoir fluids, concern reservoir geochemistry, while the third, which is a swelling test, aimed to study gas injection, investigated a synthetic reservoir fluid with hydrocarbon components up to C30. Two pieces of equipment were used: a sapphire cell with a maximum pressure rating of 400 bar and a high pressure apparatus called Hercule with a maximum pressure of 1500 bar. For each fluid, the saturation pressure was measured. For various pressure levels below saturation, the coexisting liquid and gas phases were sampled at constant pressure, and subsequently analyzed by gas chromatography. In the gas injection study, sampling was repeated with different quantities of injection gas. Compared to a n-paraffin with the same number of carbon atoms, aromatic hydrocarbons appear to stay preferentially in the liquid phase, as do cycloalkanes to a lesser extent. The gaseous phase is slightly enriched in isoalkanes. These fractionation effects are less pronounced near the critical region. These phenomena have been modeled with a cubic equation of state combined with a group contribution mixing rule. L'étude du fractionnement des hydrocarbures légers entre les phases gazeuses et liquides intéresse plusieurs domaines dans le cadre de l'exploitation des gisements. En géochimie de réservoir l'évolution de la composition de la fraction légère peut

  18. Riemann zeros and phase transitions via the spectral operator on fractal strings

    International Nuclear Information System (INIS)

    Herichi, Hafedh; Lapidus, Michel L

    2012-01-01

    The spectral operator was introduced by Lapidus and van Frankenhuijsen (2006 Fractal Geometry, Complex Dimensions and Zeta Functions: Geometry and Spectra of Fractal Strings) in their reinterpretation of the earlier work of Lapidus and Maier (1995 J. Lond. Math. Soc. 52 15–34) on inverse spectral problems and the Riemann hypothesis. In essence, it is a map that sends the geometry of a fractal string onto its spectrum. In this review, we present the rigorous functional analytic framework given by Herichi and Lapidus (2012) and within which to study the spectral operator. Furthermore, we give a necessary and sufficient condition for the invertibility of the spectral operator (in the critical strip) and therefore obtain a new spectral and operator-theoretic reformulation of the Riemann hypothesis. More specifically, we show that the spectral operator is quasi-invertible (or equivalently, that its truncations are invertible) if and only if the Riemann zeta function ζ(s) does not have any zeros on the vertical line Re(s) = c. Hence, it is not invertible in the mid-fractal case when c= 1/2 , and it is quasi-invertible everywhere else (i.e. for all c ∈ (0, 1) with c≠ 1/2 ) if and only if the Riemann hypothesis is true. We also show the existence of four types of (mathematical) phase transitions occurring for the spectral operator at the critical fractal dimension c= 1/2 and c = 1 concerning the shape of the spectrum, its boundedness, its invertibility as well as its quasi-invertibility. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical in honour of Stuart Dowker’s 75th birthday devoted to ‘Applications of zeta functions and other spectral functions in mathematics and physics’. (review)

  19. Spectral phase encoding of ultra-short optical pulse in time domain for OCDMA application.

    Science.gov (United States)

    Wang, Xu; Wada, Naoya

    2007-06-11

    We propose a novel reconfigurable time domain spectral phase encoding (SPE) scheme for coherent optical code-division-multiple-access application. In the proposed scheme, the ultra-short optical pulse is stretched by dispersive device and the SPE is done in time domain using high speed phase modulator. The time domain SPE scheme is robust to wavelength drift of the light source and is very flexible and compatible with the fiber optical system. Proof-of-principle experiments of encoding with 16-chip, 20 GHz/chip binary-phase-shift-keying codes and 1.25 Gbps data transmission have been successfully demonstrated together with an arrayed-wave-guide decoder.

  20. Study on spectral entropy of two-phase flow density wave instability

    International Nuclear Information System (INIS)

    Zhang Zuoyi

    1992-05-01

    By using mathematic proof, spectral entropy calculations for simple examples and a practical two-phase flow system, it has been proved that under the same stochastic input, the output spectral entropy of a stable linear system is in maximum, while for an unstable linear system, its entropy is in relative lower level. Because the spectral entropy describes the output uncertainty of a system and the second law of thermodynamics rules the direction of natural tendency, the spontaneous process can develop only toward the direction of uncertainty increasing, and the opposite is impossible. It seems that the physical mechanism of the stability of a system can be explained as following: Any deviation from its original state of a stable system will reduce the spectral entropy and violate the natural tendency so that the system will return to original state. On the contrary, the deviation from its original state of an unstable system will increase the spectral entropy that will enhance the deviation and the system will be further away from its original state

  1. Quantitative measurement of phase variation amplitude of ultrasonic diffraction grating based on diffraction spectral analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Meiyan, E-mail: yphantomohive@gmail.com; Zeng, Yingzhi; Huang, Zuohua, E-mail: zuohuah@163.com [Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, Guangdong 510006 (China)

    2014-09-15

    A new method based on diffraction spectral analysis is proposed for the quantitative measurement of the phase variation amplitude of an ultrasonic diffraction grating. For a traveling wave, the phase variation amplitude of the grating depends on the intensity of the zeroth- and first-order diffraction waves. By contrast, for a standing wave, this amplitude depends on the intensity of the zeroth-, first-, and second-order diffraction waves. The proposed method is verified experimentally. The measured phase variation amplitude ranges from 0 to 2π, with a relative error of approximately 5%. A nearly linear relation exists between the phase variation amplitude and driving voltage. Our proposed method can also be applied to ordinary sinusoidal phase grating.

  2. Reduction of Musical Noise in Spectral Subtraction Method Using Subframe Phase Randomization

    Energy Technology Data Exchange (ETDEWEB)

    Seok, J.W.; Bae, K.S. [Kyungpook National University, Taegu (Korea)

    1999-06-01

    The Subframe phase randomization method is applied to the spectral subtraction method to reduce the musical noise in nonvoicing region after speech enhancement. The musical noise in the spectral subtraction method is the result of the narrowband tonal components that appearing somewhat periodically in the spectrogram of unvoiced and silence regions. Thus each synthesis frame in nonvoicing region is divided into several subframes to broaden the narrowband spectrum, and then phases of silence and unvoiced regions are randomized to eliminate the tonal components in the spectrum while keeping the shape of the amplitude spectrum. Performance assessments based on visual inspection of spectrogram, objective measure, and informal subjective listening tests demonstrate the superiority of the proposed algorithm. (author). 7 refs., 5 figs.

  3. Power spectral density of velocity fluctuations estimated from phase Doppler data

    OpenAIRE

    Jicha Miroslav; Lizal Frantisek; Jedelsky Jan

    2012-01-01

    Laser Doppler Anemometry (LDA) and its modifications such as PhaseDoppler Particle Anemometry (P/DPA) is point-wise method for optical nonintrusive measurement of particle velocity with high data rate. Conversion of the LDA velocity data from temporal to frequency domain – calculation of power spectral density (PSD) of velocity fluctuations, is a non trivial task due to nonequidistant data sampling in time. We briefly discuss possibilities for the PSD estimation and specify limitations caused...

  4. Measurement of spectral phase noise in a cryogenically cooled Ti:Sa amplifier (Conference Presentation)

    Science.gov (United States)

    Nagymihaly, Roland S.; Jójárt, Péter; Börzsönyi, Ádám.; Osvay, Károly

    2017-05-01

    In most of cases the drift of the carrier envelope phase (CEP) of a chirped pulse amplifier (CPA) system is determined only [1], being the relevant parameter at laser-matter interactions. The need of coherent combination of multiple amplifier channels to further increase the peak power of pulses requires interferometric precision [2]. For this purpose, the stability of the group delay of the pulses may become equally important. Further development of amplifier systems requires the investigation of phase noise contributions of individual subsystems, like amplifier stages. Spectrally resolved interferometry (SRI), which is a completely linear optical method, makes the measurement of spectral phase noise possible of basically any part of a laser system [3]. By utilizing this method, the CEP stability of water-cooled Ti:Sa based amplifiers was investigated just recently, where the effects of seed and pump energy, repetition rate, and the cooling crystal mounts were thoroughly measured [4]. We present a systematic investigation on the noise of the spectral phase, including CEP, of laser pulses amplified in a cryogenically-cooled Ti:Sa amplifier of a CPA chain. The double-pass amplifier was built in the sample arm of a compact Michelson interferometer. The Ti:Sa crystal was cooled below 30 °K. The inherent phase noise was measured for different operation modes, as at various repetition rates, and pump depletion. Noise contributions of the vacuum pumps and the cryogenic refrigerator were found to be 43 and 47 mrad, respectively. We have also identified CEP noise having thermal as well as mechanical origin. Both showed a monotonically decreasing tendency towards higher repetition rates. We found that the widths of the noise distributions are getting broader towards lower repetition rates. Spectral phase noise with and without amplification was measured, and we found no significant difference in the phase noise distributions. The mechanical vibration was also measured in

  5. Multi-spectral quantitative phase imaging based on filtration of light via ultrasonic wave

    Science.gov (United States)

    Machikhin, A. S.; Polschikova, O. V.; Ramazanova, A. G.; Pozhar, V. E.

    2017-07-01

    A new digital holographic microscopy scheme for multi-spectral quantitative phase imaging is proposed and implemented. It is based on acousto-optic filtration of wide-band low-coherence light at the entrance of a Mach-Zehnder interferometer, recording and digital processing of interferograms. The key requirements for the acousto-optic filter are discussed. The effectiveness of the technique is demonstrated by calculating the phase maps of human red blood cells at multiple wavelengths in the range 770-810 nm. The scheme can be used for the measurement of dispersion of thin films and biological samples.

  6. A quantitative infrared spectral library of vapor phase chemicals: applications to environmental monitoring and homeland defense

    Science.gov (United States)

    Sharpe, Steven W.; Johnson, Timothy J.; Sams, Robert L.

    2004-12-01

    The utility of infrared spectroscopy for monitoring and early warning of accidental or deliberate chemical releases to the atmosphere is well documented. Regardless of the monitoring technique (open-path or extractive) or weather the spectrometer is passive or active (Fourier transform or lidar) a high quality, quantitative reference library is essential for meaningful interpretation of the data. Pacific Northwest National Laboratory through the support of the Department of Energy has been building a library of pure, vapor phase chemical species for the last 4 years. This infrared spectral library currently contains over 300 chemicals and is expected to grow to over 400 chemicals before completion. The library spectra are based on a statistical fit to many spectra at different concentrations, allowing for rigorous error analysis. The contents of the library are focused on atmospheric pollutants, naturally occurring chemicals, toxic industrial chemicals and chemicals specifically designed to do damage. Applications, limitations and technical details of the spectral library will be discussed.

  7. Theoretical study of titanium phases; Etude theorique des phases du titane

    Energy Technology Data Exchange (ETDEWEB)

    Trinite, V

    2006-10-15

    The aim of this work is to obtain a good understanding of the phase diagram of titanium within density functional theory. This diagram is composed of the alpha phase, the high pressure omega phase and the high temperature beta phase. This requires the differences in total energy to be predicted with a great precision, because these differences are around 50 meV. I find the omega phase to be the most stable one by ab initio calculation at zero temperature and pressure, in contradiction to the experimental results. I find this inversion of the stability also appears in titanium dioxide and zirconium. I have analyzed all the approximations brought into play in the ab initio approach. I have estimated the zero point energy and studied the impact of including the semi-core states as well as the effect of the exchange-correlation functionals. The conclusion is that the usual approximations for the exchange-correlation generate the biggest part of the error. A possible correction is to take into account the electronic self-interaction. I have apply this correction to the semi-core states and find a systematic improvement of the cell parameters, but no improvement on the phase stability. So I can conclude that a better description of the exchange interaction on the localized 3d states is needed. Although the standard functionals of exchange-correlation are not accurate enough to predict the phase diagrams of titanium, they perform well in describing physical properties less demanding in terms of precision, like elastic constants. However, I find important that the predicted equilibrium volume must be precise, as these properties are found strongly dependent on the volume. (author)

  8. Two-harmonic complex spectral-domain optical coherence tomography using achromatic sinusoidal phase modulation

    Science.gov (United States)

    Lu, Sheng-Hua; Huang, Siang-Ru; Chou, Che-Chung

    2018-03-01

    We resolve the complex conjugate ambiguity in spectral-domain optical coherence tomography (SD-OCT) by using achromatic two-harmonic method. Unlike previous researches, the optical phase of the fiber interferometer is modulated by an achromatic phase shifter based on an optical delay line. The achromatic phase modulation leads to a wavelength-independent scaling coefficient for the two harmonics. Dividing the mean absolute value of the first harmonic by that of the second harmonic in a B-scan interferogram directly gives the scaling coefficient. It greatly simplifies the determination of the magnitude ratio between the two harmonics without the need of third harmonic and cumbersome iterative calculations. The inverse fast Fourier transform of the complex-valued interferogram constructed with the scaling coefficient, first and second harmonics yields a full-range OCT image. Experimental results confirm the effectiveness of the proposed achromatic two-harmonic technique for suppressing the mirror artifacts in SD-OCT images.

  9. Characterizing inner-shell with spectral phase interferometry for direct electric-field reconstruction

    Science.gov (United States)

    Mashiko, Hiroki; Yamaguchi, Tomohiko; Oguri, Katsuya; Suda, Akira; Gotoh, Hideki

    2014-01-01

    In many atomic, molecular and solid systems, Lorentzian and Fano profiles are commonly observed in a broad research fields throughout a variety of spectroscopies. As the profile structure is related to the phase of the time-dependent dipole moment, it plays an important role in the study of quantum properties. Here we determine the dipole phase in the inner-shell transition using spectral phase interferometry for direct electric-field reconstruction (SPIDER) with isolated attosecond pulses (IAPs). In addition, we propose a scheme for pulse generation and compression by manipulating the inner-shell transition. The electromagnetic radiation generated by the transition is temporally compressed to a few femtoseconds in the extreme ultraviolet (XUV) region. The proposed pulse-compression scheme may provide an alternative route to producing attosecond pulses of light. PMID:25510971

  10. Spectral Cascade-Transport Turbulence Model Development for Two-Phase Flows

    Science.gov (United States)

    Brown, Cameron Scott

    Turbulence modeling remains a challenging problem in nuclear reactor applications, particularly for the turbulent multiphase flow conditions in nuclear reactor subchannels. Understanding the fundamental physics of turbulent multiphase flows is crucial for the improvement and further development of multiphase flow models used in reactor operation and safety calculations. Reactor calculations with Reynolds-averaged Navier-Stokes (RANS) approach continue to become viable tools for reactor analysis. The on-going increase in available computational resources allows for turbulence models that are more complex than the traditional two-equation models to become practical choices for nuclear reactor computational fluid dynamic (CFD) and multiphase computational fluid dynamic (M-CFD) simulations. Similarly, increased computational capabilities continue to allow for higher Reynolds numbers and more complex geometries to be evaluated using direct numerical simulation (DNS), thus providing more validation and verification data for turbulence model development. Spectral turbulence models are a promising approach to M-CFD simulations. These models resolve mean flow parameters as well as the turbulent kinetic energy spectrum, reproducing more physical details of the turbulence than traditional two-equation type models. Previously, work performed by other researchers on a spectral cascade-transport model has shown that the model behaves well for single and bubbly twophase decay of isotropic turbulence, single and two-phase uniform shear flow, and single-phase flow in a channel without resolving the near-wall boundary layer for relatively low Reynolds number. Spectral models are great candidates for multiphase RANS modeling since bubble source terms can be modeled as contributions to specific turbulence scales. This work focuses on the improvement and further development of the spectral cascadetransport model (SCTM) to become a three-dimensional (3D) turbulence model for use in M

  11. Nature de la phase basse temperature des verres de spin Heisenberg en dimension 3

    OpenAIRE

    PETIT , Dorothée

    2002-01-01

    I. A Campbell (Directeur) D.R. Grempel F. Hippert (rapporteur) O. Martin P. Norblad (rapporteur) E. Vincent; La question de l'existence d'une réelle transition de phase entre l'état paramagnétique et l'état verre de spin est une question qui a été débattue pendant de nombreuses années. Il semble dorénavant admis que le gel des spins à basse température ne se fasse pas de façon progressive, et l'existence d'une véritable transition à T9. finie est communément acceptée, mais de nombreuses quest...

  12. Film thickness measurement based on nonlinear phase analysis using a Linnik microscopic white-light spectral interferometer.

    Science.gov (United States)

    Guo, Tong; Chen, Zhuo; Li, Minghui; Wu, Juhong; Fu, Xing; Hu, Xiaotang

    2018-04-20

    Based on white-light spectral interferometry and the Linnik microscopic interference configuration, the nonlinear phase components of the spectral interferometric signal were analyzed for film thickness measurement. The spectral interferometric signal was obtained using a Linnik microscopic white-light spectral interferometer, which includes the nonlinear phase components associated with the effective thickness, the nonlinear phase error caused by the double-objective lens, and the nonlinear phase of the thin film itself. To determine the influence of the effective thickness, a wavelength-correction method was proposed that converts the effective thickness into a constant value; the nonlinear phase caused by the effective thickness can then be determined and subtracted from the total nonlinear phase. A method for the extraction of the nonlinear phase error caused by the double-objective lens was also proposed. Accurate thickness measurement of a thin film can be achieved by fitting the nonlinear phase of the thin film after removal of the nonlinear phase caused by the effective thickness and by the nonlinear phase error caused by the double-objective lens. The experimental results demonstrated that both the wavelength-correction method and the extraction method for the nonlinear phase error caused by the double-objective lens improve the accuracy of film thickness measurements.

  13. A first-order spectral phase transition in a class of periodically modulated Hermitian Jacobi matrices

    Directory of Open Access Journals (Sweden)

    Irina Pchelintseva

    2008-01-01

    Full Text Available We consider self-adjoint unbounded Jacobi matrices with diagonal \\(q_n = b_{n}n\\ and off-diagonal entries \\(\\lambda_n = n\\, where \\(b_{n}\\ is a \\(2\\-periodical sequence of real numbers. The parameter space is decomposed into several separate regions, where the spectrum of the operator is either purely absolutely continuous or discrete. We study the situation where the spectral phase transition occurs, namely the case of \\(b_{1}b_{2} = 4\\. The main motive of the paper is the investigation of asymptotics of generalized eigenvectors of the Jacobi matrix. The pure point part of the spectrum is analyzed in detail.

  14. Study of transformations by annealing of the body. Centred cubic {gamma} phase of uranium-molybdenum alloys; Etude des transformations par revenu de la phase {gamma} cubique centree des alliages uranium-molybdene

    Energy Technology Data Exchange (ETDEWEB)

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

    1959-06-15

    By annealing at different temperatures, we have studied the transformations of the body centred cubic {gamma} phase for two alloys containing 6 and 10 per cent molybdenum by weight respectively. There is a return to the equilibrium state by formation of the stable {alpha} orthorhombic and {epsilon} ordered tetragonal phases, following two types of reaction: - pearlite transformation by nucleation and growth from the grain boundaries, preponderant when the annealing takes place at temperature above 400 deg. C, and identical for the two types of alloys. This reaction has already been studied by numerous authors, who have constructed the corresponding TTT curves, - transformation inside the grains of the quenched solid solution when annealing takes place at 400 deg. C or below: 6 per cent alloy - precipitation of fine a phase particles, followed by progressive ordering of the solid solution enriched in molybdenum, 10 per cent alloy - formation of small ordered regions and then a fine a phase precipitate. In the course of this work we have paid particular attention to the study of intragranular reactions after low-temperature annealing, the reactions involved in this case not having been explained up to the present. The {gamma} phase transformation has been studied by means of three techniques: micrography - microhardness tests - X-ray diffraction. (author) [French] Nous avons etudie les transformations par revenu a differentes temperatures, de la phase {gamma} cubique centree des alliages U-Mo trempes, pour deux alliages a 6 et a 10 pour cent de molybdene en poids. Il y a retour a l'etat d'equilibre par formation des phases stables {alpha} orthorhombique et quadratique ordonnee, suivant deux types de reactions: - transformation perlitique par germination et croissance a partir des joints de grains, preponderante lorsque le recuit a lieu a temperature superieure a 400 deg. C, et identique pour les deux types d'alliages. Cette reaction a deja ete etudiee par de nombreux

  15. Fiber Bragg grating for spectral phase optical code-division multiple-access encoding and decoding

    Science.gov (United States)

    Fang, Xiaohui; Wang, Dong-Ning; Li, Shichen

    2003-08-01

    A new method for realizing spectral phase optical code-division multiple-access (OCDMA) coding based on step chirped fiber Bragg gratings (SCFBGs) is proposed and the corresponding encoder/decoder is presented. With this method, a mapping code is introduced for the m-sequence address code and the phase shift can be inserted into the subgratings of the SCFBG according to the mapping code. The transfer matrix method together with Fourier transform is used to investigate the characteristics of the encoder/decoder. The factors that influence the correlation property of the encoder/decoder, including index modulation and bandwidth of the subgrating, are identified. The system structure is simple and good correlation output can be obtained. The performance of the OCDMA system based on SCFBGs has been analyzed.

  16. Spectral phase effects on nonlinear resonant photochemistry of 1,3-cyclohexadiene in solution

    International Nuclear Information System (INIS)

    Carroll, E.C.; Pearson, B.J.; Florean, A.C.; Bucksbaum, P.H.; Sension, Roseanne J.

    2006-01-01

    We have investigated the ring opening of 1,3-cyclohexadiene to form 1,3,5-cis-hexatriene (Z-HT) using optical pulse shaping to enhance multiphoton excitation. A closed-loop learning algorithm was used to search for an optimal spectral phase function, with the effectiveness or fitness of each optical pulse assessed using the UV absorption spectrum. The learning algorithm was able to identify pulses that increased the formation of Z-HT by as much as a factor of 2 and to identify pulse shapes that decreased solvent fragmentation while leaving the formation of Z-HT essentially unaffected. The highest yields of Z-HT did not occur for the highest peak intensity laser pulses. Rather, negative quadratic phase was identified as an important control parameter in the formation of Z-HT

  17. Measurement of the lepton {tau} spectral functions and applications to quantum chromodynamic; Mesure des fonctions spectrales du lepton {tau} et applications a la chromodynamique quantique

    Energy Technology Data Exchange (ETDEWEB)

    Hoecker, A [Paris-11 Univ., 91 - Orsay (France). Lab. de l' Accelerateur Lineaire; [Universite de Paris Sud, 91 - Orsay (France)

    1997-04-18

    This thesis presents measurements of the {tau} vector (V) and axial-vector (A) hadronic spectral functions and phenomenological studies in the framework of quantum chromodynamics (QCD). Using the hypothesis of conserved vector currents (CVC), the dominant two- and four-pion vector spectral functions are compared to the corresponding cross sections from e{sup +}e{sup -} annihilation. A combined fit of the pion form factor from {tau} decays and e{sup +}e{sup -} data is performed using different parametrizations. The mass and the width of the {rho}{sup {+-}}(770) and the {rho}{sup 0}(770) are separately determined in order to extract possible isospin violating effects. The mass and width differences are measured to be M{sub {rho}{sup {+-}}{sub (770)} - M{sub {rho}{sup 0}}{sub (770)}=(0.0{+-}1.0) MeV/c{sup 2} and {gamma}{sub {rho}{sup {+-}}{sub (770)} - {gamma}{sub {rho}{sup 0}}{sub (770)}=(0.1 {+-} 1.9) MeV/c{sup 2}. Several QCD chiral sum rules involving the difference (V - A) of the spectral functions are compared to their measurements. The Borel-transformed Das-Mathur-Okubo sum rule is used to measure the pion polarizability to be {alpha}{sub E}=(2.68{+-}0.91) x 10{sup -4} fm{sup 3}. The {tau} vector and axial-vector hadronic widths and certain spectral moments are exploited to measure {alpha}{sub s} and non-perturbative contributions at the {tau} mass scale. The best, and experimentally and theoretically most robust, determination of {alpha}{sub s}(M{sub {tau}}) is obtained from the inclusive (V + A) fit that yields {alpha}{sub s}(M{sub {tau}})= 0.348{+-}0.017 giving {alpha}{sub s}(M{sub Z})=0.1211 {+-} 0.0021 after the evolution to the mass of the Z boson. The approach of the Operator Product Expansion (OPE) is tested experimentally by means of an evolution of the {tau} hadronic width to masses smaller that the {tau} mass. Using the difference (V - A) of the spectral functions allows one to directly measure the dominant non-perturbative OPE dimension to be D=6

  18. Conjugate Etalon Spectral Imager (CESI) & Scanning Etalon Methane Mapper (SEMM), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The Conjugate Etalon Spectral Imaging (CESI) concept enables the development of miniature instruments with high spectral resolution, suitable for LEO missions aboard...

  19. Direct determination of enthalpies of solid phase reactions by immersion method; Determination directe des enthalpies de reaction en phase solide par une methode de plongee

    Energy Technology Data Exchange (ETDEWEB)

    Roux, A; Richard, M; Eyraud, L; Stevanovic, M; Elston, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    It is not generally possible to measure the enthalpy change corresponding to solid phase reactions using the dynamic differential thermal analysis method because these reactions are usually too slow at the temperature of operation of present equipment. A ballistic differential thermal analysis apparatus has been developed which is based on an immersion-compensation method; it overcomes the difficulties previously encountered. This apparatus has been used after calibration for determining the enthalpies of formation of calcium and cadmium titanates. and also the Wigner energies of BeO, MgO and Al{sub 2}O{sub 3} samples irradiated at variable dose at a temperature of under 100 deg. C. (authors) [French] Il n'est generalement pas possible de mesurer la variation d'enthalpie correspondant aux reactions en phase solide par la methode d'analyse thermique differentielle dynamique. En effet, ces reactions sont le plus souvent trop lentes aux temperatures d'utilisation des dispositifs actuels. Un appareil d'analyse thermique differentielle balistique, base sur une methode de plongee avec compensation, a ete mis au point et permet de surmonter les difficultes precedentes. Apres etalonnages, cet appareil a ete utilise pour la determination des enthalpies de formation du titanate de calcium et du titanate de cadmium ainsi que pour celle des energies Wigner emmagasinees dans des echantillons de BeO, MgO et Al{sub 2}O{sub 3} irradies a une temperature inferieure a 100 deg. C et a differentes doses. (auteurs)

  20. Réforme des budgets publics en Chine - phase II | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    orientation à donner aux réformes, facilitera les expériences de budgétisation participative dans toute la Chine, favorisera les échanges d'idées entre les organismes oeuvrant dans le domaine des finances et des budgets publics et informera les élus, ...

  1. Réforme des budgets publics en Chine - phase II | CRDI - Centre de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    orientation à donner aux réformes, facilitera les expériences de budgétisation participative dans toute la Chine, favorisera les échanges d'idées entre les organismes oeuvrant dans le domaine des finances et des budgets publics et informera les élus, ...

  2. Mapping the spectral phase of isolated attosecond pulses by extreme-ultraviolet emission spectrum.

    Science.gov (United States)

    Liu, Candong; Zeng, Zhinan; Li, Ruxin; Xu, Zhizhan; Nisoli, Mauro

    2015-04-20

    An all-optical method is proposed for the measurement of the spectral phase of isolated attosecond pulses. The technique is based on the generation of extreme-ultraviolet (XUV) radiation in a gas by the combination of an attosecond pulse and a strong infrared (IR) pulse with controlled electric field. By using a full quantum simulation, we demonstrate that, for particular temporal delays between the two pulses, the IR field can drive back to the parent ions the photoelectrons generated by the attosecond pulse, thus leading to the generation of XUV photons. It is found that the generated XUV spectrum is notably sensitive to the chirp of the attosecond pulse, which can then be reliably retrieved. A classical quantum-path analysis is further used to quantitatively explain the main features exhibited in the XUV emission.

  3. The Northwest Infrared (NWIR) gas-phase spectral database of industrial and environmental chemicals: Recent updates

    Energy Technology Data Exchange (ETDEWEB)

    Brauer, Carolyn S.; Johnson, Timothy J.; Blake, Thomas A.; Sharpe, Steven W.; Sams, Robert L.; Tonkyn, Russell G.

    2014-05-22

    With continuing improvements in both standoff- and point-sensing techniques, there is an ongoing need for high-quality infrared spectral databases. The Northwest Infrared Database (NWIR) contains quantitative, gas-phase infrared spectra of nearly 500 pure chemical species that can be used for a variety of applications such as atmospheric monitoring, biomass burning studies, etc. The data, recorded at 0.1 cm-1 resolution, are pressure broadened to one atmosphere (N2) in order to mimic atmospheric conditions. Each spectrum is a composite composed of multiple individual measurements. Recent updates to the database include over 60 molecules that are known or suspected biomass-burning effluents. Examples from this set of measurements will be presented and experimental details will be discussed in the context of the utility of NWIR for environmental applications.

  4. Spectral induced polarization of the three-phase system CO2 - brine - sand under reservoir conditions

    Science.gov (United States)

    Börner, Jana H.; Herdegen, Volker; Repke, Jens-Uwe; Spitzer, Klaus

    2017-01-01

    The spectral complex conductivity of a water-bearing sand during interaction with carbon dioxide (CO2) is influenced by multiple, simultaneous processes. These processes include partial saturation due to the replacement of conductive pore water with CO2 and chemical interaction of the reactive CO2 with the bulk fluid and the grain-water interface. We present a laboratory study on the spectral induced polarization of water-bearing sands during exposure to and flow-through by CO2. Conductivity spectra were measured successfully at pressures up to 30 MPa and 80 °C during active flow and at steady-state conditions concentrating on the frequency range between 0.0014 and 100 Hz. The frequency range between 0.1 and 100 Hz turned out to be most indicative for potential monitoring applications. The presented data show that the impact of CO2 on the electrolytic conductivity may be covered by a model for pore-water conductivity, which depends on salinity, pressure and temperature and has been derived from earlier investigations of the pore-water phase. The new data covering the three-phase system CO2-brine-sand further show that chemical interaction causes a reduction of surface conductivity by almost 20 per cent, which could be related to the low pH-value in the acidic environment due to CO2 dissolution and the dissociation of carbonic acid. The quantification of the total CO2 effect may be used as a correction during monitoring of a sequestration in terms of saturation. We show that this leads to a correct reconstruction of fluid saturation from electrical measurements. In addition, an indicator for changes of the inner surface area, which is related to mineral dissolution or precipitation processes, can be computed from the imaginary part of conductivity. The low frequency range between 0.0014 and 0.1 Hz shows additional characteristics, which deviate from the behaviour at higher frequencies. A Debye decomposition approach is applied to isolate the feature dominating the

  5. Realization and study of spectral properties of the ISGRI gamma-ray camera; Mise en oeuvre et etude des proprietes spectrales de la gamma-camera ISGRI

    Energy Technology Data Exchange (ETDEWEB)

    Limousin, O

    2001-11-01

    This work evaluates spectroscopic and physical properties of CdTe detectors in view of assembling a large number on a new generation spectro-imager for space gamma-ray astronomy. Study, optimization, realization and calibration of modular detection units of the ISGRI camera are described. After a description of the experimental context of the INTEGRAL program and a review of the physical processes involved in gamma-ray photon detectors, we present an analysis of the properties of CdTe detectors attempting to be so exhaustive as possible. We propose the base point of a global model, which relates charge transport properties, spectral response and possible instabilities in the detectors. We propose a new formulation of the Hecht relation that describes charge loss as a function of the detector charge transport properties. We discuss at length the method of charge loss correction and its consequences on the associated integrated electronics definition. Finally, we illustrate our instrument capabilities using as an example the observation of titanium 44 lines in historical supernovae. (author)

  6. The transition radiation. I: numerical study of the angular and spectral distributions; Le rayonnement de transition optique. I: etude numerique des distributions angulaires et spectrales

    Energy Technology Data Exchange (ETDEWEB)

    Couillaud, Ch.; Haouat, G

    1999-07-01

    The optical transition radiation (OTR) is extensively used since many years as a beam visualisation tool on electron accelerators and serves to monitor the beam during its transport adjustment. Its spatial and temporal characteristics make it very attractive as a diagnostic tool and allow measurements of the beam energy and transverse and longitudinal emittances. We present a numerical study of the transition radiation process in the optical region of the radiated spectrum (OTR) and in the higher part (XTR). Spatial and spectral properties are described. They are used to describe experimental observations performed on the ELSA electron-beam facility. An analytical description of the angular distributions of visible radiation emitted by birefringent targets, used as OTR sources, is also proposed. We also analyze interference phenomena between two OTR sources and show the advantage of using this interferometer as a diagnostic tool for tenth MeV electron accelerators. At last, we present an analytical model allowing to design a soft X-ray source to be installed on the ELSA facility and using either a multi-foil stack or a multilayer of two materials of different permittivities. (authors)

  7. Modulating the amplitude and phase of the complex spectral degree of coherence with plasmonic interferometry

    Science.gov (United States)

    Li, Dongfang; Pacifici, Domenico

    The spectral degree of coherence describes the correlation of electromagnetic fields, which plays a key role in many applications, including free-space optical communications and speckle-free bioimaging. Recently, plasmonic interferometry, i.e. optical interferometry that employs surface plasmon polaritons (SPPs), has enabled enhanced light transmission and high-sensitivity biosensing, among other applications. It offers new ways to characterize and engineer electromagnetic fields using nano-structured thin metal films. Here, we employ plasmonic interferometry to demonstrate full control of spatial coherence at length scales comparable to the wavelength of the incident light. Specifically, by measuring the diffraction pattern of several double-slit plasmonic structures etched on a metal film, the amplitude and phase of the degree of spatial coherence is determined as a function of slit-slit separation distance and incident wavelength. When the SPP contribution is turned on (i.e., by changing the polarization of the incident light from TE to TM illumination mode), strong modulation of both amplitude and phase of the spatial coherence is observed. These findings may help design compact modulators of optical spatial coherence and other optical elements to shape the light intensity in the far-field.

  8. Two-phase screw-type engine - problems of the filling process; Zweiphasen-Schraubenmotor - Probleme des Fuellungsvorganges

    Energy Technology Data Exchange (ETDEWEB)

    Kauder, K.; Kliem, B. [Dortmund Univ. (Germany). FG Fluidenergiemaschinen

    1998-12-31

    The two-phase screw-type engine presents itself as a expansion engine in a trilateral-flash-cycle to use waste heat in the lower temperature range, because this displacement engine is able to expand working fluids with a high proportion of liquid. Due to the low critical velocity and the blocking flow, the two-phase flow in the inlet port of the screw-type engine has a great influence on the quality of energy transformation. A novel filling system with rotating short nozzles is presented. Less dissipation during the filling process is expected by this system, because the flash evaporation of the fluid will occur in the working chamber and not in the inlet port of the screw-type engine. (orig.) [Deutsch] Der Zweiphasen-Schraubenmotor besitzt als Expansionsmaschine in Trilateral-Flash-Cycle-Prozessen zur Nutzung von Abwaerme mit niedriger Temperatur deutliche Vorteile, da dieser Maschinentyp in der Lage ist, Arbeitsfluide mit einem hohen Fluessigkeitsanteil zu expandieren. Die Zweiphasenstroemung im Einlassbereich des Schraubenmotors hat aufgrund ihrer geringen kritischen Geschwindigkeit und der damit verbundenen blockierten Stroemung einen signifikanten Einfluss auf die Fuellung der Arbeitskammer und der Energiewandlungsguete des Motors. Ein hier vorgestelltes neuartiges Fuellungssystem mit rotierenden Kurzduesen laesst eine verbesserte Fuellung des Zweiphasen-Schraubenmotors erwarten, da es erst in den Arbeitskammern zur Flashverdampfung kommt. (orig.)

  9. Miniature Compressive Ultra-spectral Imaging System Utilizing a Single Liquid Crystal Phase Retarder

    Science.gov (United States)

    August, Isaac; Oiknine, Yaniv; Abuleil, Marwan; Abdulhalim, Ibrahim; Stern, Adrian

    2016-03-01

    Spectroscopic imaging has been proved to be an effective tool for many applications in a variety of fields, such as biology, medicine, agriculture, remote sensing and industrial process inspection. However, due to the demand for high spectral and spatial resolution it became extremely challenging to design and implement such systems in a miniaturized and cost effective manner. Using a Compressive Sensing (CS) setup based on a single variable Liquid Crystal (LC) retarder and a sensor array, we present an innovative Miniature Ultra-Spectral Imaging (MUSI) system. The LC retarder acts as a compact wide band spectral modulator. Within the framework of CS, a sequence of spectrally modulated images is used to recover ultra-spectral image cubes. Using the presented compressive MUSI system, we demonstrate the reconstruction of gigapixel spatio-spectral image cubes from spectral scanning shots numbering an order of magnitude less than would be required using conventional systems.

  10. Phase sensitive spectral domain interferometry for label free biomolecular interaction analysis and biosensing applications

    Science.gov (United States)

    Chirvi, Sajal

    Biomolecular interaction analysis (BIA) plays vital role in wide variety of fields, which include biomedical research, pharmaceutical industry, medical diagnostics, and biotechnology industry. Study and quantification of interactions between natural biomolecules (proteins, enzymes, DNA) and artificially synthesized molecules (drugs) is routinely done using various labeled and label-free BIA techniques. Labeled BIA (Chemiluminescence, Fluorescence, Radioactive) techniques suffer from steric hindrance of labels on interaction site, difficulty of attaching labels to molecules, higher cost and time of assay development. Label free techniques with real time detection capabilities have demonstrated advantages over traditional labeled techniques. The gold standard for label free BIA is surface Plasmon resonance (SPR) that detects and quantifies the changes in refractive index of the ligand-analyte complex molecule with high sensitivity. Although SPR is a highly sensitive BIA technique, it requires custom-made sensor chips and is not well suited for highly multiplexed BIA required in high throughput applications. Moreover implementation of SPR on various biosensing platforms is limited. In this research work spectral domain phase sensitive interferometry (SD-PSI) has been developed for label-free BIA and biosensing applications to address limitations of SPR and other label free techniques. One distinct advantage of SD-PSI compared to other label-free techniques is that it does not require use of custom fabricated biosensor substrates. Laboratory grade, off-the-shelf glass or plastic substrates of suitable thickness with proper surface functionalization are used as biosensor chips. SD-PSI is tested on four separate BIA and biosensing platforms, which include multi-well plate, flow cell, fiber probe with integrated optics and fiber tip biosensor. Sensitivity of 33 ng/ml for anti-IgG is achieved using multi-well platform. Principle of coherence multiplexing for multi

  11. Mapping a Part of Neuquén Basin in Argentina by Global-phase H/V Spectral Ratio

    NARCIS (Netherlands)

    Nishitsuji, Yohei; Ruigrok, E.N.; Gomez, M.; Draganov, Deyan

    2015-01-01

    We investigated the applicability of global phases (epicentral distances of ≥ 120° and ≥ 150°) for the H/V spectral ratio to identify the fundamental resonance frequency. We applied the method to delineate a part of Neuquén basin in Argentina without the need for active seismic sources. We obtained

  12. Mapping a part of Neuquen Basin in Argentina by global-phase H/V spectral ratio

    NARCIS (Netherlands)

    Nishitsuji, Y.; Ruigrok, E.; Gomez, M.; Draganov, D.S.

    2015-01-01

    We investigated the applicability of global phases (epicentral distances of ? 120° and ? 150°) for the H/V spectral ratio to identify the fundamental resonance frequency. We applied the method to delineate a part of Neuquén basin in Argentina without the need for active seismic sources. We obtained

  13. Theoretical extension and experimental demonstration of spectral compression in second-harmonic generation by Fresnel-inspired binary phase shaping

    Science.gov (United States)

    Li, Baihong; Dong, Ruifang; Zhou, Conghua; Xiang, Xiao; Li, Yongfang; Zhang, Shougang

    2018-05-01

    Selective two-photon microscopy and high-precision nonlinear spectroscopy rely on efficient spectral compression at the desired frequency. Previously, a Fresnel-inspired binary phase shaping (FIBPS) method was theoretically proposed for spectral compression of two-photon absorption and second-harmonic generation (SHG) with a square-chirped pulse. Here, we theoretically show that the FIBPS can introduce a negative quadratic frequency phase (negative chirp) by analogy with the spatial-domain phase function of Fresnel zone plate. Thus, the previous theoretical model can be extended to the case where the pulse can be transformed limited and in any symmetrical spectral shape. As an example, we experimentally demonstrate spectral compression in SHG by FIBPS for a Gaussian transform-limited pulse and show good agreement with the theory. Given the fundamental pulse bandwidth, a narrower SHG bandwidth with relatively high intensity can be obtained by simply increasing the number of binary phases. The experimental results also verify that our method is superior to that proposed in [Phys. Rev. A 46, 2749 (1992), 10.1103/PhysRevA.46.2749]. This method will significantly facilitate the applications of selective two-photon microscopy and spectroscopy. Moreover, as it can introduce negative dispersion, hence it can also be generalized to other applications in the field of dispersion compensation.

  14. Determining the von Mises stress power spectral density for frequency domain fatigue analysis including out-of-phase stress components

    NARCIS (Netherlands)

    Bonte, M.H.A.; de Boer, Andries; Liebregts, R.

    This paper provides a new formula to take into account phase differences in the determination of an equivalent von Mises stress power spectral density (PSD) from multiple random inputs. The obtained von Mises PSD can subsequently be used for fatigue analysis. The formula was derived for use in the

  15. Formulation of the energetic spectral distribution of in pile neutron flux (energies greater than a few hundred electron volts) (1963); Formulation des repartitions spectrales energetiques de flux neutroniques en pile (energies superieures a quelques centaines d'electrons-volts) (1963)

    Energy Technology Data Exchange (ETDEWEB)

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

    1964-07-01

    In the present report an expression is deduced for the spectral distribution of flux of over a few hundred electron volts; it is valid for most cases of thermal neutron reactors. This expression is: {psi}(E) = K [{psi}{sub o}(E) + h {psi}{sub e}(E)] {psi}{sub o}(E) is the so-called 'homogeneous' constituent of the flux; it corresponds approximately to the case of an infinite homogeneous medium; it is of the type: Y(V - E) e{sup (b{radical}}{sup E)}/E + Y(E-V) F E{sup {upsilon}} e{sup -{beta}}{sup E} The parameters V and F are such that {psi}{sub o}(E) and its derivative are continuous at the junction energy V. {psi}{sub e}(E) is the 'heterogeneous' constituent of the flux; it is of the type: E{sup {upsilon}} e{sup -{beta}}{sup E}. The various parameters of {psi}(E) are on the one hand characteristic of the nature of the reactor moderator, and on the other hand determined by a resonant flux measurement and one, or possibly two, measurements using a fast neutron threshold detector. We have been led furthermore to define an expression for the threshold reaction section which is more exact than the conventional transition function. (author) [French] Il est etabli, dans le present rapport, une formulation {psi}(E) des repartitions spectrales de flux au-dessus de quelques centaines d'electron-s volts, valable dans la majeure partie des cas de piles dites a neutrons thermiques. Cette formulation s'exprime: {psi}(E) = K [{psi}{sub o}(E) + h {psi}{sub e}(E)] {psi}{sub o}(E) est la composante dite 'homogene' du flux; elle correspond a peu pres au cas d'un milieu infini homogene; elle est du type: Y(V - E) e{sup (b{radical}}{sup E)}/E + Y(E-V) F E{sup {upsilon}} e{sup -{beta}}{sup E} les parametres V et F sont tels que {psi}{sub o}(E) et sa derivee soient continues a l'energie de jonction V. {psi}{sub e} est la composante dite 'heterogene' du flux ; elle est du type: E{sup {upsilon}} e{sup -{beta}}{sup E}. Les differents parametres de {psi}(E) sont, d'une part

  16. Radio Spectral Imaging of Reflective MHD Waves during the Impulsive Phase of a Solar Flare

    Science.gov (United States)

    Yu, S.; Chen, B.; Reeves, K.

    2017-12-01

    We report a new type of coherent radio bursts observed by the Karl G. Jansky Very Large Array (VLA) in 1-2 GHz during the impulsive phase of a two-ribbon flare on 2014 November 1, which we interpret as MHD waves reflected near the footpoint of flaring loops. In the dynamic spectrum, this burst starts with a positive frequency drift toward higher frequencies until it slows down near its highest-frequency boundary. Then it turns over and drifts toward lower frequencies. The frequency drift rate in its descending and ascending branch is between 50-150 MHz/s, which is much slower than type III radio bursts associated with fast electron beams but close to the well-known intermediate drift bursts, or fiber bursts, which are usually attributed to propagating whistler or Alfvenic waves. Thanks to VLA's unique capability of imaging with spectrometer-like temporal and spectral resolution (50 ms and 2 MHz), we are able to obtain an image of the radio source at every time and frequency in the dynamic spectrum where the burst is present and trace its spatial evolution. From the imaging results, we find that the radio source firstly moves downward toward one of the flaring ribbons before it "bounces off" at the lowest height (corresponding to the turnover frequency in the dynamic spectrum) and moves upward again. The measured speed in projection is at the order of 1-2 Mm/s, which is characteristic of Alfvenic or fast-mode MHD waves in the low corona. We conclude that the radio burst is emitted by trapped nonthermal electrons in the flaring loop carried along by a large-scale MHD wave. The waves are probably launched during the eruption of a magnetic flux rope in the flare impulsive phase.

  17. Power spectral density of velocity fluctuations estimated from phase Doppler data

    Science.gov (United States)

    Jedelsky, Jan; Lizal, Frantisek; Jicha, Miroslav

    2012-04-01

    Laser Doppler Anemometry (LDA) and its modifications such as PhaseDoppler Particle Anemometry (P/DPA) is point-wise method for optical nonintrusive measurement of particle velocity with high data rate. Conversion of the LDA velocity data from temporal to frequency domain - calculation of power spectral density (PSD) of velocity fluctuations, is a non trivial task due to nonequidistant data sampling in time. We briefly discuss possibilities for the PSD estimation and specify limitations caused by seeding density and other factors of the flow and LDA setup. Arbitrary results of LDA measurements are compared with corresponding Hot Wire Anemometry (HWA) data in the frequency domain. Slot correlation (SC) method implemented in software program Kern by Nobach (2006) is used for the PSD estimation. Influence of several input parameters on resulting PSDs is described. Optimum setup of the software for our data of particle-laden air flow in realistic human airway model is documented. Typical character of the flow is described using PSD plots of velocity fluctuations with comments on specific properties of the flow. Some recommendations for improvements of future experiments to acquire better PSD results are given.

  18. Power spectral density of velocity fluctuations estimated from phase Doppler data

    Directory of Open Access Journals (Sweden)

    Jicha Miroslav

    2012-04-01

    Full Text Available Laser Doppler Anemometry (LDA and its modifications such as PhaseDoppler Particle Anemometry (P/DPA is point-wise method for optical nonintrusive measurement of particle velocity with high data rate. Conversion of the LDA velocity data from temporal to frequency domain – calculation of power spectral density (PSD of velocity fluctuations, is a non trivial task due to nonequidistant data sampling in time. We briefly discuss possibilities for the PSD estimation and specify limitations caused by seeding density and other factors of the flow and LDA setup. Arbitrary results of LDA measurements are compared with corresponding Hot Wire Anemometry (HWA data in the frequency domain. Slot correlation (SC method implemented in software program Kern by Nobach (2006 is used for the PSD estimation. Influence of several input parameters on resulting PSDs is described. Optimum setup of the software for our data of particle-laden air flow in realistic human airway model is documented. Typical character of the flow is described using PSD plots of velocity fluctuations with comments on specific properties of the flow. Some recommendations for improvements of future experiments to acquire better PSD results are given.

  19. ``Statistical treatment of the spectral properties of plasmas in local thermodynamical equilibrium using a screened hydrogenic model``; ``Traitement statistique des proprietes spectrales des plasmas a l`equilibre thermodynamique local dans le cadre du modele hydrogenique ecrante``

    Energy Technology Data Exchange (ETDEWEB)

    Faussurier, G.

    1996-12-31

    A new screened hydrogenic model is presented. The screening constants depend both on the principal n and orbital l quantum numbers. They have been obtained from numerical fits over a large data base containing ionization potentials and one-electron excitation energies of ions. A rapid and original method to compute the bound-bound and bound-free oscillator strengths is proposed. The discrete spectrum and the series continuum are connected by continuity, and the sum rules are respected. The screened hydrogenic average atom is well-adapted to describe multicharged ion plasmas in local thermodynamic equilibrium (LTE). Using the key principle of statistical mechanics, it is shown first that this model is properly defined and thermodynamically coherent. Secondly, a new method of detailed ionization stage accounting of a LTE plasma is explained. It can be used to reconstruct the distribution of integer charge states in such a plasma from any average atom model. The l -splitting allows one-electron transitions between two subshells with the same principal quantum number n. They may be of great importance when the Rosseland opacity is computed. Though, methods of classical statistical mechanics are required to calculate the distribution of the configurations around the average atom one and so to improve the spectral opacities. The splitting in integer ionic stages can be easily included. The formalism is tested by comparisons with theoretical and experimental results published in the literature. From the photoabsorption spectra encountered, the main results are the correct estimations of both the Rosseland opacity and the detailed charge degrees accounting. (author).

  20. Contribution to the study of the flow of adsorbed phases. Enrichment of binary Gaseous mixtures; Contribution a l'etude de l'ecoulement des phases absorbees. Enrichissement des melanges gazeux binaires

    Energy Technology Data Exchange (ETDEWEB)

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

    1962-12-15

    The research which makes up this thesis is concerned both with the problems of adsorption an chromatographic columns and of catalysis, which involve the surface properties of these solids, and with problems of isotope separation by gaseous diffusion. In this latter case, the flow in the two-dimensional adsorbed phase is a secondary phenomenon but it is nevertheless necessary to know its influence on the separation factor. Up to the present time very little work has been published on this subject, the importance of which needs no stressing. The author has devised very sensitive techniques making it possible to study the flow of two-dimensional phases in micro-porous bodies. He has demonstrated not only the role of the relative pressure and of the nature of the components (gas and solid) but also the relationship between the mobility of the adsorbate and the thermodynamic characteristics of the adsorption. The author has treated numerous examples involving the diffusion either of pure gases (n-butane, n-pentane, isopentane), or of binary mixtures, and has shown on the one hand that the separative effect of the two-dimensional flow at the interface is a maximum in the neighbourhood of the monolayer, and on the other hand that the mass effect is of the second order with respect to the structural factor of the diffusing molecule. The problem considered is of importance both from a fundamental point of view and from that of its industrial applications. (author) [French] Le sujet de travail de cette these interesse aussi bien les problemes d'adsorption sur colonne de chromatographie et de catalyse, qui font intervenir directement les proprietes superficielles des solides, que ceux concernant la separation isotopique par diffusion gazeuse. Dans ce dernier cas l'ecoulement en phase adsorbee bidimensiormelle est un phenomene secondaire dont i1 faut cependant connaitre l'effet sur le facteur de separation. Pratiquement aucun travail fondamental n'a encore ete publie sur ce

  1. Complex method for angular-spectral analysis of volume phase diffraction gratings recorded in photopolymers

    Czech Academy of Sciences Publication Activity Database

    Vojtíšek, Petr; Květoň, M.; Richter, I.

    2016-01-01

    Roč. 11, February (2016), č. článku 16009. ISSN 1990-2573 R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : Photopolymers * diffraction gratings * angular-spectral maps * spectral selectivity * angular selectivity Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.975, year: 2016

  2. Generation of a new spectral format, the lifetime synchronous spectrum (LiSS), using phase-resolved fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Shaver, J.M.; McGown, L.B.

    1994-01-01

    A new fluorescence spectral format is introduced in which fluorescence lifetime is shown as a function of synchronously scanned wavelength to generate a Lifetime Synchronous Spectrum (LiSS). Lifetimes are determined in the frequency domain with the use of Phase-Resolved Fluorescence Spectroscopy (PRFS) to obtain the phase of the fluorescence signal. Theory and construction of the LiSS are presented and experimental results are shown for solutions of single components and simple binary and ternary mixtures. These results show how the lifetime information in the LiSS augments the steady-state intensity information of a standard synchronous spectrum, providing unique information for identification of components and resolution of overlapping spectral peaks. The LiSS technique takes advantage of noise reduction inherent in the extraction of lifetime from PRFS in addition to standard spectral smoothing techniques. The precision of phase determination through PRFS is found to be comparable to that of direct phase measurements at normal fluorescence intensities and superior for low-intensity signals

  3. Cloud phase identification of Arctic boundary-layer clouds from airborne spectral reflection measurements: test of three approaches

    Directory of Open Access Journals (Sweden)

    A. Ehrlich

    2008-12-01

    Full Text Available Arctic boundary-layer clouds were investigated with remote sensing and in situ instruments during the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR campaign in March and April 2007. The clouds formed in a cold air outbreak over the open Greenland Sea. Beside the predominant mixed-phase clouds pure liquid water and ice clouds were observed. Utilizing measurements of solar radiation reflected by the clouds three methods to retrieve the thermodynamic phase of the cloud are introduced and compared. Two ice indices IS and IP were obtained by analyzing the spectral pattern of the cloud top reflectance in the near infrared (1500–1800 nm wavelength spectral range which is characterized by ice and water absorption. While IS analyzes the spectral slope of the reflectance in this wavelength range, IS utilizes a principle component analysis (PCA of the spectral reflectance. A third ice index IA is based on the different side scattering of spherical liquid water particles and nonspherical ice crystals which was recorded in simultaneous measurements of spectral cloud albedo and reflectance.

    Radiative transfer simulations show that IS, IP and IA range between 5 to 80, 0 to 8 and 1 to 1.25 respectively with lowest values indicating pure liquid water clouds and highest values pure ice clouds. The spectral slope ice index IS and the PCA ice index IP are found to be strongly sensitive to the effective diameter of the ice crystals present in the cloud. Therefore, the identification of mixed-phase clouds requires a priori knowledge of the ice crystal dimension. The reflectance-albedo ice index IA is mainly dominated by the uppermost cloud layer (τ<1.5. Therefore, typical boundary-layer mixed-phase clouds with a liquid cloud top layer will

  4. Spectral Narrowing of a Varactor-Integrated Resonant-Tunneling-Diode Terahertz Oscillator by Phase-Locked Loop

    Science.gov (United States)

    Ogino, Kota; Suzuki, Safumi; Asada, Masahiro

    2017-12-01

    Spectral narrowing of a resonant-tunneling-diode (RTD) terahertz oscillator, which is useful for various applications of terahertz frequency range, such as an accurate gas spectroscopy, a frequency reference in various communication systems, etc., was achieved with a phase-locked loop system. The oscillator is composed of an RTD, a slot antenna, and a varactor diode for electrical frequency tuning. The output of the RTD oscillating at 610 GHz was down-converted to 400 MHz by a heterodyne detection. The phase noise was transformed to amplitude noise by a balanced mixer and fed back into the varactor diode. The loop filter for a stable operation is discussed. The spectral linewidth of 18.6 MHz in free-running operation was reduced to less than 1 Hz by the feedback.

  5. Optimal and robust control of quantum state transfer by shaping the spectral phase of ultrafast laser pulses.

    Science.gov (United States)

    Guo, Yu; Dong, Daoyi; Shu, Chuan-Cun

    2018-04-04

    Achieving fast and efficient quantum state transfer is a fundamental task in physics, chemistry and quantum information science. However, the successful implementation of the perfect quantum state transfer also requires robustness under practically inevitable perturbative defects. Here, we demonstrate how an optimal and robust quantum state transfer can be achieved by shaping the spectral phase of an ultrafast laser pulse in the framework of frequency domain quantum optimal control theory. Our numerical simulations of the single dibenzoterrylene molecule as well as in atomic rubidium show that optimal and robust quantum state transfer via spectral phase modulated laser pulses can be achieved by incorporating a filtering function of the frequency into the optimization algorithm, which in turn has potential applications for ultrafast robust control of photochemical reactions.

  6. Spectrally-Tunable Infrared Camera Based on Highly-Sensitive Quantum Well Infrared Photodetectors, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a SPECTRALLY-TUNABLE INFRARED CAMERA based on quantum well infrared photodetector (QWIP) focal plane array (FPA) technology. This will build on...

  7. High Spectral Resolution, High Cadence, Imaging X-ray Microcalorimeters for Solar Physics - Phase 2 Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Microcalorimeter x-ray instruments are non-dispersive, high spectral resolution, broad-band, high cadence imaging spectrometers. We have been developing these...

  8. Conjugate Etalon Spectral Imager (CESI) & Scanning Etalon Methane Mapper (SEMM), Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of the CESI focal plane and optics technology will lead to miniaturized hyperspectral and SWIR-band spectral imaging instrumentation compatible with...

  9. Determining the von Mises stress power spectral density for frequency domain fatigue analysis including out-of-phase stress components

    Science.gov (United States)

    Bonte, M. H. A.; de Boer, A.; Liebregts, R.

    2007-04-01

    This paper provides a new formula to take into account phase differences in the determination of an equivalent von Mises stress power spectral density (PSD) from multiple random inputs. The obtained von Mises PSD can subsequently be used for fatigue analysis. The formula was derived for use in the commercial vehicle business and was implemented in combination with Finite Element software to predict and analyse fatigue failure in the frequency domain.

  10. Spectral Weighting Functions for Single-symbol Phase-noise Specifications in OFDM Systems

    NARCIS (Netherlands)

    Hoeksema, F.W.; Schiphorst, Roelof; Slump, Cornelis H.

    2003-01-01

    For the specification of phase-noise requirements for the front-end of a HiperLAN/2 system we investigated available literature on the subject. Literature differed in several aspects. One aspect is in the type of phase-noise used (Wiener phase-noise or small-angle phase noise). A Wiener phase-noise

  11. Thermal Neutron Spectral and Spatial Distributions in Light-Water-Moderated Uranium Lattices; Distributions Spectrale et Spatiale des Neutrons Thermiques dans des Reseaux a Uranium et a Eau Leger; Spektral'noe i prostranstvennoe raspredelenie teplovykh nejtronov v uranovykh reshetkakh s vodnym zamedlitelem; Distribuciones Espectral y Espacial de los Neutrones Termicos en los Reticulados de Uranio Moderados por Agua Ligera

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, J.; Volpe, J. J.; Klein, D.; Schmidt, E.; Gelbard, E. [Bettis Atomic Power Laboratory, Pittsburgh, PA (United States)

    1964-02-15

    , qui est utilise universellement pour l'etude des reacteurs. Le noyau de Nelkin est une description plus recente et plus detaillee du noyau de diffusion. Comme les taux d'absorption des neutrons thermiques obtenus par le calcul dependent du choix du noyau de diffusion, notamment lorsque le spectre du flux de neutrons est non maxwellien, on a concu une autre serie d'experiences d'activation a l'aide de l'assemblage TRX pour verifier le noyau de diffusion de facon plus directe. Ces experiences ont eu lieu dans des conditions ou la deformation spectrale etait essentiellement due a un empoisonnement uniforme. Les mesures etaient faites dans un tube rempli d'eau, de 10 cm de diametre, monte dans le reseau TRX. La paroi du tube etait remplie de {sup 10}B en poudre grace auquel l'interieur du tube se trouvait isole du reseau des reacteurs pour les energies inferieures a 10 keV. Les taux d'activation relatifs des neutrons thermiques et les formes radiales des detecteurs sensibles aux spectres ont ete mesures dans deux cas correspondant respectivement a une distribution pratiquement maxwellienne (H{sub 2}O pure) et a un spectre fortement deforme par la presence de cadmium. En vue de cette experience, on a procede a un calcul a 12 groupes a l'aide de chacun des noyaux avec une approximation P{sub 3}. La forme du milieu de ralentissement a ete obtenue par un calcul aux valeurs propres portant sur les formes des modes spatiaux que prend le systeme et qui decroissent exponentiellement selon la lethargie, calcul complete par les mesures des formes d'activation epicadmique. Selon que le milieu etait empoisonne ou non, les taux d'activation relatifs calcules a l'aide des deux noyaux accusaient une difference pouvant atteindre 10%, Les donnees experimentales ont ete compares aux resultats des calculs faits avec le noyau de Radkowsky et celui de Nelkin. La comparaison est nettement en faveur du spectre dur prevu grace au noyau de Nelkin. (author) [Spanish] Se exponen los experimentos

  12. Spectral broadening of 25 fs laser pulses via self-phase modulation in a neon filled hollow core fibre

    Energy Technology Data Exchange (ETDEWEB)

    Weichert, Stefan

    2017-05-15

    The goal of this work was the realisation of a setup for spectral broadening and subsequent compression of 25 fs laser pulses provided by a commercial Ti:Sapphire based CPA laser system by means of the hollow core fibre chirped mirror compressor technique. For the spectral broadening a vessel containing the hollow waveguide filled with a noble gas serving as the nonlinear medium was set up and an alignment procedure was developed. Neon was chosen as the nonlinear medium for the self-phase modulation of the pulses. With this setup spectral broadening, sufficient for supporting sub 5 fs pulses, was observed. The spectra at different input energies and neon gas pressures were measured and the stability of these and their respective Fourier transform-limited pulses determined in order to find an operating point. For the compression of the self-phase modulated pulses a chirped mirror compressor was designed and set up, but not tested yet. The layout of a single-shot intensity autocorrelator capable of estimating the pulse duration of sub 10 fs pulses was given.

  13. Spectral broadening of 25 fs laser pulses via self-phase modulation in a neon filled hollow core fibre

    International Nuclear Information System (INIS)

    Weichert, Stefan

    2017-05-01

    The goal of this work was the realisation of a setup for spectral broadening and subsequent compression of 25 fs laser pulses provided by a commercial Ti:Sapphire based CPA laser system by means of the hollow core fibre chirped mirror compressor technique. For the spectral broadening a vessel containing the hollow waveguide filled with a noble gas serving as the nonlinear medium was set up and an alignment procedure was developed. Neon was chosen as the nonlinear medium for the self-phase modulation of the pulses. With this setup spectral broadening, sufficient for supporting sub 5 fs pulses, was observed. The spectra at different input energies and neon gas pressures were measured and the stability of these and their respective Fourier transform-limited pulses determined in order to find an operating point. For the compression of the self-phase modulated pulses a chirped mirror compressor was designed and set up, but not tested yet. The layout of a single-shot intensity autocorrelator capable of estimating the pulse duration of sub 10 fs pulses was given.

  14. Phase noise measurements with a cryogenic power-splitter to minimize the cross-spectral collapse effect

    Science.gov (United States)

    Hati, Archita; Nelson, Craig W.; Pappas, David P.; Howe, David A.

    2017-11-01

    The cross-spectrum noise measurement technique enables enhanced resolution of spectral measurements. However, it has disadvantages, namely, increased complexity, inability of making real-time measurements, and bias due to the "cross-spectral collapse" (CSC) effect. The CSC can occur when the spectral density of a random process under investigation approaches the thermal noise of the power splitter. This effect can severely bias results due to a differential measurement between the investigated noise and the anti-correlated (phase-inverted) noise of the power splitter. In this paper, we report an accurate measurement of the phase noise of a thermally limited electronic oscillator operating at room temperature (300 K) without significant CSC bias. We mitigated the problem by cooling the power splitter to liquid helium temperature (4 K). We quantify errors of greater than 1 dB that occur when the thermal noise of the oscillator at room temperature is measured with the power splitter at temperatures above 77 K.

  15. Improvement in remote sensing of low vegetation cover in arid regions by correcting vegetation indices for soil ''noise''; Etude des propriétés spectrales des sols arides appliquée à l'amélioration des indices de végétation obtenus par télédétection

    Energy Technology Data Exchange (ETDEWEB)

    Escadafal, R. [Institut Francais de Recherche Scientifique pour le Developpement en Cooperation, Bondy (France); Huete, A.

    1991-05-23

    The variations of near-infrared red reflectance ratios of ten aridic soil samples were correlated with a ''redness index'' computed from red and green spectral bands. These variations have been shown to limit the performances of vegetation indices (NDVI and SAVI) in discriminating low vegetation covers. The redness index is used to adjust for this ''soil noise''. Dala simulated for vegetation densities of 5 to 15% cover showed that the sensitivity of the corrected vegetation indices was significantly improved. Specifically, the ''noise-corrected'' SAVI was able to assess vegetation amounts with an error four times smaller than the uncorrected NDVI. These promising results should lead to a significant improvement in assessing biomass in arid lands from remotely sensed data. (author) [French] Les variations du rapport de la réflectance dans les bandes rouge et infrarouge sont mises en relation avec un (( indice de coloration )) pouf une série de dix sols arides. Ces variations gZnent fortement la détection des faibles taux de couvert végétal avec les indices de végétation (NDVI et SAVI) calculés à partir de ces deux bandes. Il est proposé d’utiliser l’indice de coloration comme facteur de correction de ce (( bruit )) dû au sol. Une simulation de la reflectance des sols avec une couverture végétale variant de O à 15 % en évidence un doublement de la sensibilité des indices de végétation ainsi corrigés. En particulier, le SAVI corrigé permet d’estimer le taux de végétation avec une erreur quatre fois inférieure à celle du NDVI non corrigé. Ces premiers résultats devraient conduire à une amélioration sensible de la mesure de la biomasse végétale des régions arides par télédétection. (author)

  16. Self-consistent random phase approximation - application to systems of strongly correlated fermions; Approximation des phases aleatoires self-consistante - applications a des systemes de fermions fortement correles

    Energy Technology Data Exchange (ETDEWEB)

    Jemai, M

    2004-07-01

    In the present thesis we have applied the self consistent random phase approximation (SCRPA) to the Hubbard model with a small number of sites (a chain of 2, 4, 6,... sites). Earlier SCRPA had produced very good results in other models like the pairing model of Richardson. It was therefore interesting to see what kind of results the method is able to produce in the case of a more complex model like the Hubbard model. To our great satisfaction the case of two sites with two electrons (half-filling) is solved exactly by the SCRPA. This may seem a little trivial but the fact is that other respectable approximations like 'GW' or the approach with the Gutzwiller wave function yield results still far from exact. With this promising starting point, the case of 6 sites at half filling was considered next. For that case, evidently, SCRPA does not any longer give exact results. However, they are still excellent for a wide range of values of the coupling constant U, covering for instance the phase transition region towards a state with non zero magnetisation. We consider this as a good success of the theory. Non the less the case of 4 sites (a plaquette), as indeed all cases with 4n sites at half filling, turned out to have a problem because of degeneracies at the Hartree Fock level. A generalisation of the present method, including in addition to the pairs, quadruples of Fermions operators (called second RPA) is proposed to also include exactly the plaquette case in our approach. This is therefore a very interesting perspective of the present work. (author)

  17. Comparative seasonal variations of spectral signatures of broad-leaved and coniferous stands from Landsat data. Comparison with other perennial environments; Evolutions saisonnières comparées des signatures spectrales de feuillus et de conifères à partir de données Landsat : comparaison avec d'autres milieux pérennes

    Energy Technology Data Exchange (ETDEWEB)

    Chaume, R. [Office de la Recherche Scientifique et Technique Outre-Mer, Bondy (France); Combeau, A.

    1984-07-01

    Spectral signatures of two distinct forest test areas were identified from digital data including 15 LANDSAT scenes covering the same geographical area: a broad-leaved forest (oak and beech) and a coniferous forest (scotch pine). Seasonal variations of the signatures were examined and were expressed in terms of various data: date, solar height and phenological state of vegetation cover. Results were compared to these obtained from other perennial surface conditions (grassland, bare soils) . Range of the seasonal variations of radiance is noted, as well as evolutionary peculiarities on each band and between themes. Rationing of spectral bands (particularly MSS 5 and 7) and their variation with time are specified [French] A partir des données numériques de 15 scènes LANDSAT sur un même secteur géographique, l e s auteurs définissent les signatures spectrales de deux milieux forestiers distincts: une futaie de chênes-hêtres et une futaie de pins sylvestres, et ils étudient l a variation saisonnière de ces signatures. Ils tentent d'interpréter cette variabilité en fonction de la date de saisie des données, donc de l a hauteur du soleil et de l'état phénologique du couvert végétal. Ils comparent les résultats 5 ceux obtenus sur d'autres milieux pérennes (prairie, sols nus). L'amplitude des variations saisonnières des luminances est précisée, ainsi que les modalités particulières de l'évolution sur certains canaux ou entre les deux thèmes. Les auteurs étudient également les rapports de luminance inter-canaux (5 et 7 en particulier) et leur évolution dans le temps.

  18. A study of phase transformations processes in 0,5 to 4% mo uranium-molybdenum alloys; Etude des processus des transformations dans les alliages uranium-molybdene de teneur 0,5 a 4% en poids de molybdene

    Energy Technology Data Exchange (ETDEWEB)

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

    1959-06-15

    Isothermal and continuous cooling transformations process have been established on uranium-molybdenum alloys containing 0,5 to 4 w% Mo. Transformations process of the {beta} and {gamma} solid solutions are described. These processes depend upon molybdenum concentration. Out of the {beta} solid solution phase appears an eutectoid decomposition of {beta} to ({alpha} + {gamma}) or the formation of a martensitic phase {alpha}''. The {gamma} solid solution shows a decomposition of {gamma} to ({alpha} + {gamma}) or ({alpha} + {gamma}'), or a formation of martensitic phases a' or a'{sub b}. The U-Mo equilibrium diagram is discussed, particularly in low concentrations zones. Limits between domains ({alpha} + {gamma}) and ({beta} + {gamma}), ({beta} + {gamma}) and {gamma}, ({beta} + {gamma}) and {beta}, have been determined. (author) [French] Les processus des transformations isothermes, et au cours de refroidissements continus ont ete etablis sur les alliages uranium-molybdene de 0,5 a 4 % en poids de Mo. Ceci a permis de mettre en evidence les processus des transformations de solutions solides {beta} et {gamma}, differents suivant la teneur en molybdene de l'alliage. Dans le premier cas il y a decomposition eutectoide de {beta} en ({alpha} + {gamma}) ou formations d'une phase martensitique {alpha}''. Dans le second cas il y a decomposition de {gamma} soit en ({alpha} + {gamma}) soit en ({alpha} + {gamma}') suivant la temperature, ou bien formation des phases martensitiques {alpha}' ou {alpha}'{sub b}. Le diagramme d'equilibre, uranium-molybdene est sujet a de nombreuses controverses, en particulier dans la zone des faibles concentrations. Les limites entre les domaines ({alpha} + {gamma}) et ({beta} + {gamma}), ({beta} + {gamma}) et {gamma}, ({beta} + {gamma}) et {beta}, ont ete determinees. (auteur)

  19. Oligosaccharides and glycolipids addition in charged lamellar phases; Addition d`oligosaccharides et de glycolipides dans des phases lamellaires chargees

    Energy Technology Data Exchange (ETDEWEB)

    Ricoul, F

    1997-09-26

    The aim of this work is to study the addition of oligosaccharides and glycolipids in lamellar phases of the cationic surfactant DDAB (di-dodecyl-dimethyl-ammonium bromide). Two steps have been followed: the determination of phases prisms and the thermodynamic interpretation in terms of molecular interactions. In order to characterize these systems, two new experimental small angle scattering methods have been perfected: 1) a neutron scattering contrast variation method which allows to study the adsorption of aqueous solution in bilayers and 2) a capillary concentration gradient method to establish directly and quantitatively the phases diagrams of ternary systems by X rays scattering. It has been pointed out that the oligosaccharides induce a depletion attractive force on the lamellar-lamellar equilibrium of the DDAB when they are excluded of the most concentrated phase. For the two studied glycolipids: 2-O lauroyl-saccharose and N-lauroyl N-nonyl lactitol, the ternary phase diagrams water-DDAB-glycolipid have been established in terms of temperature. Critical points at ambient temperature have been given. The osmotic pressure in concentrated lamellar phases has been measured. It has been shown that glycolipids increase the hydration repulsion at short distance and that the electrostatic repulsion is outstanding and unchanged at high distance if there is at less 1 mole percent of ionic surfactant. In a dilute solution, glycolipids decrease the maximum swelling of lamellar phases, with a competition between the lamellar phase and the micellae dilute phase for water. (O.M.). 165 refs.

  20. Spectral study of the luminescence produced by the excitation of noble gases by alpha-rays; Etude spectrale de la luminescence due a l'excitation des gaz rares par les rayons alpha

    Energy Technology Data Exchange (ETDEWEB)

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

    1960-07-01

    Luminescence spectra of the noble gases He, A, Kr and Xe are studied under excitation by {alpha} rays. It is shown that the energy is transferred from excited levels of these gases to Hg and N{sub 2} impurities for impurity concentrations respectively less than 10{sup 6} and 10{sup 4}. These results confirm previous measurements concerning the period of luminescence and its variations versus nitrogen concentration in noble gases. (author) [French] On etudie les spectres de luminescence des gaz rares, He, A, Kr et Xe excites par une source intense de rayons {alpha}. Le transfert d'energie des etats excites des gaz rares sur les impuretes mercure et azote pour des concentrations respectives de ces impuretes inferieures a 1 ppm et 100 ppm est demontre. Ces resultats confirment les mesures anterieures concernant la duree de luminescence et ses variations avec la concentration d'azote dans les gaz rares. (auteur)

  1. Méthodes d'analyse/synthèse et représentations optimales des sons musicaux basées sur la réduction de données spectrales

    OpenAIRE

    Rochebois , Thierry

    1997-01-01

    This thesis introduces a method that allows systematic reduction of data representing musical sounds. This method and its variants allows fast and dynamic synthesis of musical sounds.; Les applications de l'analyse et de la synthèse des sons musicaux sont primordiales a l'heure du multimédia. Nous présentons une méthode permettant d'analyser et de synthétiser les sons musicaux. Cette méthode, illustrée au chapitre 2, se décompose en trois étapes. La première repose sur une analyse spectrale p...

  2. Nuclear techniques and cross-correlation methods for spectral analysis in two-phase flow measurements in mineral pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Luis E.B.; Salgado, Cesar M., E-mail: brandaos@ien.gov.br, E-mail: otero@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Divisao de Radiofarmacos; Sicilliano, Umberto C.C.S., E-mail: umberto.cassara@poli.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Dept. de Metalurgia

    2013-07-01

    In mineral industry is common to use water to transport pellets inside pipes. In these units, the correct measurement of flow (both solid and liquid phase) is important to guarantee a safe operation. Cross correlation flow meters are devices specially suited to be used in dual-phase flow and they are based on measure the transit time due the disturbances registered between two points, in our case gamma attenuation from radioactive sources. The emphasis of this work is the application of gamma transmission and scattering technique associated with spectral analysis methods to measure the flow of solid phase in a liquid fluid in side the pipe. The detectors and the sources are out side of the tube and are positioned 10.0 cm distant one from the other. The photons of transmission/scattering gamma radiation were registered, and across-correlation method was applied to measure the flow and spectral analysis was used to study the flow profile inside the pipe. (author)

  3. Spectral and photometric study of the symbiotic nova RS ophiuchus in quiet phase

    Science.gov (United States)

    Kondratyeva, L.; Rspaev, F.; Krugov, M.; Serebryanskiy, A.

    2017-07-01

    The results of spectral and photometric study of the recurrent Nova RS Ophiuchus are presented and discussed. Observations were carried out in 2009-2016. During these eight years the fluxes of HI and FeII emission lines have slightly decreased by a factor of 3 - 4. Hα and Hβ exhibit double-peaked profiles with a central absorption. The ratio of the blue and red peaks intensities(V/R) varies from 0.3 to 1.0 for Hβ and from 0.4 to 0.7 for Hα. Possible correlations between changes of the ratio and other spectral parameters were investigated. Dependence of V/R on the radial velocity of absorbtion component is found out.

  4. Predicting the effective response of bulk polycrystalline ferroelectric ceramics via improved spectral phase field methods

    Science.gov (United States)

    Vidyasagar, A.; Tan, W. L.; Kochmann, D. M.

    2017-09-01

    Understanding the electromechanical response of bulk polycrystalline ferroelectric ceramics requires scale-bridging approaches. Recent advances in fast numerical methods to compute the homogenized mechanical response of materials with heterogeneous microstructure have enabled the solution of hitherto intractable systems. In particular, the use of a Fourier-based spectral method as opposed to the traditional finite element method has gained significant interest in the homogenization of periodic microstructures. Here, we solve the periodic, electro-mechanically-coupled boundary value problem at the mesoscale of polycrystalline ferroelectrics in order to extract the effective response of barium titanate (BaTiO3) and lead zirconate titanate (PZT) under applied electric fields. Results include the effective electric hysteresis and the associated butterfly curve of strain vs. electric field for mean stress-free electric loading. Computational predictions of the 3D polycrystalline response show convincing agreement with our experimental electric cycling and strain hysteresis data for PZT-5A. In addition to microstructure-dependent effective physics, we also show how finite-difference-based approximations in the spectral solution scheme significantly reduce instability and ringing phenomena associated with spectral techniques and lead to spatial convergence with h-refinement, which have been major challenges when modeling high-contrast systems such as polycrystals.

  5. L’évolution des essais cliniques de phase 2 : « les preuves de concept » en schizophrénie

    OpenAIRE

    Frisch , Céline

    2014-01-01

    Non disponible / Not available; La schizophrénie est une maladie mentale caractérisée par une dissociation de lapersonnalité, affectant le rapport du malade à la réalité. Elle fait partie des dix maladiesles plus invalidantes.Les traitements actuels (antipsychotiques) agissent principalement sur les symptômespositifs : hallucinations et délires et ont montré leurs limites sur le reste de lasymptomatologie.Les études de preuve de concept sont des études de phase IIa. Elles ont pour but deteste...

  6. Spectral Ly{alpha}, Ly{beta}, and H{alpha} line shapes for the H atom in the presence of a magnetic field in a plasma; Profils des raies spectrales Ly{alpha}, Ly{beta}, et H{alpha} de l'atome H en presence d'un champ magnetique dans un plasma

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, H; Herman, L [Laboratoire de Recherches Physiques, Faculte des sciences, 9 Quai Saint Bernard, 75 - Paris (France); Drawin, H W [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-02-15

    This report contains numerical data of the line shapes of Ly{alpha}, Ly{beta}, and H{alpha} for the following parameters: 1. 10{sup 2} {<=} H [gauss] {<=} 1.2. 10{sup 5} 1. 10{sup 15}{<=} N [cm{sup -3}] {<=} 1. 10{sup 18} cm{sup -3} 1. 10{sup 4} {<=} T [deg. K] {<=} 4. 10{sup 4} where H = magnetic field strength, K = density of plasma ions, T = electron temperature. (authors) [French] Dans ce rapport, on donne les valeurs numeriques des contours des raies spectrales Ly{alpha}, Ly{beta}, et H{alpha} pour les valeurs suivantes des parametres H, N et T 1. 10{sup 2} {<=} H [gauss] {<=} 1.2. 10{sup 5} 1. 10{sup 15}{<=} N [cm{sup -3}] {<=} 1. 10{sup 18} cm{sup -3} 1. 10{sup 4} {<=} T [deg. K] {<=} 4. 10{sup 4} ou H intensite du champ magnetique, N = densite des ions, T = temperature electronique. (auteurs)

  7. A fully-coupled discontinuous Galerkin spectral element method for two-phase flow in petroleum reservoirs

    Science.gov (United States)

    Taneja, Ankur; Higdon, Jonathan

    2018-01-01

    A high-order spectral element discontinuous Galerkin method is presented for simulating immiscible two-phase flow in petroleum reservoirs. The governing equations involve a coupled system of strongly nonlinear partial differential equations for the pressure and fluid saturation in the reservoir. A fully implicit method is used with a high-order accurate time integration using an implicit Rosenbrock method. Numerical tests give the first demonstration of high order hp spatial convergence results for multiphase flow in petroleum reservoirs with industry standard relative permeability models. High order convergence is shown formally for spectral elements with up to 8th order polynomials for both homogeneous and heterogeneous permeability fields. Numerical results are presented for multiphase fluid flow in heterogeneous reservoirs with complex geometric or geologic features using up to 11th order polynomials. Robust, stable simulations are presented for heterogeneous geologic features, including globally heterogeneous permeability fields, anisotropic permeability tensors, broad regions of low-permeability, high-permeability channels, thin shale barriers and thin high-permeability fractures. A major result of this paper is the demonstration that the resolution of the high order spectral element method may be exploited to achieve accurate results utilizing a simple cartesian mesh for non-conforming geological features. Eliminating the need to mesh to the boundaries of geological features greatly simplifies the workflow for petroleum engineers testing multiple scenarios in the face of uncertainty in the subsurface geology.

  8. Spectral-domain low-coherence interferometry for phase-sensitive measurement of Faraday rotation at multiple depths.

    Science.gov (United States)

    Yeh, Yi-Jou; Black, Adam J; Akkin, Taner

    2013-10-10

    We describe a method for differential phase measurement of Faraday rotation from multiple depth locations simultaneously. A polarization-maintaining fiber-based spectral-domain interferometer that utilizes a low-coherent light source and a single camera is developed. Light decorrelated by the orthogonal channels of the fiber is launched on a sample as two oppositely polarized circular states. These states reflect from sample surfaces and interfere with the corresponding states of the reference arm. A custom spectrometer, which is designed to simplify camera alignment, separates the orthogonal channels and records the interference-related oscillations on both spectra. Inverse Fourier transform of the spectral oscillations in k-space yields complex depth profiles, whose amplitudes and phase difference are related to reflectivity and Faraday rotation within the sample, respectively. Information along a full depth profile is produced at the camera speed without performing an axial scan for a multisurface sample. System sensitivity for the Faraday rotation measurement is 0.86 min of arc. Verdet constants of clear liquids and turbid media are measured at 687 nm.

  9. A High Energy and High Efficiency Spectral Shaping Single Frequency Fiber Laser, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR phase I project proposes a tunable single frequency high energy fiber laser system for coherent Lidar systems for remote sensing. Current state-of-art...

  10. A High Energy and High Efficiency Spectral Shaping Single Frequency Fiber Laser, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR phase II project proposes a single frequency high energy fiber laser system for coherent Lidar systems for remote sensing. Current state-of-art...

  11. Smoothing by spectral dispersion using random phase modulation for inertial confinement fusion

    International Nuclear Information System (INIS)

    Rothenberg, J.E.

    1995-01-01

    Numerical simulations of beam smoothing using random phase modulation and grating dispersion are presented. Spatial spectra of the target illumination show that significantly improved smoothing at low spatial frequency is achieved while maintaining uniform intensity in the laser amplifier

  12. Thermodynamical modeling of nuclear glasses: coexistence of amorphous phases; Modelisation thermodynamique des verres nucleaires: coexistence entre phases amorphes

    Energy Technology Data Exchange (ETDEWEB)

    Adjanor, G

    2007-11-15

    Investigating the stability of borosilicate glasses used in the nuclear industry with respect to phase separation requires to estimate the Gibbs free energies of the various phases appearing in the material. In simulation, using current computational resources, a direct state-sampling of a glassy system with respect to its ensemble statistics is not ergodic and the estimated ensemble averages are not reliable. Our approach consists in generating, at a given cooling rate, a series of quenches, or paths connecting states of the liquid to states of the glass, and then in taking into account the probability to generate the paths leading to the different glassy states in ensembles averages. In this way, we introduce a path ensemble formalism and calculate a Landau free energy associated to a glassy meta-basin. This method was validated by accurately mapping the free energy landscape of a 38-atom glassy cluster. We then applied this approach to the calculation of the Gibbs free energies of binary amorphous Lennard-Jones alloys, and checked the correlation between the observed tendencies to order or to phase separate and the computed Gibbs free energies. We finally computed the driving force to phase separation in a simplified three-oxide nuclear glass modeled by a Born-Mayer-Huggins potential that includes a three-body term, and we compared the estimated quantities to the available experimental data. (author)

  13. Etude theorique des phases de densite inhomogene dans les systemes a effet Hall quantique

    OpenAIRE

    GOERBIG , Mark Oliver

    2004-01-01

    Thèse en cotutelle : Fribourg et Paris-Sud XI; The issue of this thesis is the study of the different electron-solid and quantum-liquid phases, which are found in two-dimensional electron systems under a perpendicular magnetic field. The formation of these phases is due to the strong Coulomb repulsion between the electrons of a partially filled Landau level. The energy calculations of the thesis allow one to understand recent experimental investigations, which have revealed a non-monotonic be...

  14. Characterization of Phase Transitions in PZT Ferroelectric films with spectral Ellipsometry

    Czech Academy of Sciences Publication Activity Database

    Deineka, Alexander; Suchaneck, G.; Jastrabík, Lubomír; Gerlach, G.

    11-12, - (2002), s. 377-380 ISSN 0447-6441 R&D Projects: GA MŠk LN00A015; GA ČR GA202/00/1425 Institutional research plan: CEZ:AV0Z1010921 Keywords : ferroelectric film * phase transition * film profile Subject RIV: BH - Optics, Masers, Lasers

  15. Structural and Moessbauer spectral study of the metastable phase Sm(Fe, Co, Ti)10

    International Nuclear Information System (INIS)

    Bessais, L.; Djega-Mariadassou, C.; Koch, E.

    2002-01-01

    We have performed a Moessbauer spectral analysis of nanocrystalline metastable P 6/mmm SmTi(Fe 1-x Co x ) 9 , correlated with structural transformation towards its equilibrium derivative I4/mmm SmTi(Fe 1-x Co x ) 11 . The Rietveld analysis shows that the 3g site is fully occupied, while the 6 l occupation is limited to hexagons surrounding the Fe-Fe dumb-bell pairs 2e. A specific programme for the Wigner-Seitz cell (WSC) calculation of the metastable disordered structure was used. The hyperfine parameter assignment based on the isomer shift correlation with the WSC volumes sequence leads to Co 3g preferential occupation, with Ti location in 6 l sites. The mean hyperfine field increases with Co content in connection with the enhancement of the negative core electron polarization term upon additional Co electron filling. The same trend is observed for each individual site leading to the sequence H HF {2e}≥H HF {6 l }≥H HF {3g}. (author)

  16. Ultrafast transient absorption revisited: Phase-flips, spectral fingers, and other dynamical features

    Energy Technology Data Exchange (ETDEWEB)

    Cina, Jeffrey A., E-mail: cina@uoregon.edu; Kovac, Philip A. [Department of Chemistry and Biochemistry, and Oregon Center for Optical, Molecular, and Quantum Science, University of Oregon, Eugene, Oregon 97403 (United States); Jumper, Chanelle C. [Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6 (Canada); Dean, Jacob C.; Scholes, Gregory D., E-mail: gscholes@princeton.edu [Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States)

    2016-05-07

    We rebuild the theory of ultrafast transient-absorption/transmission spectroscopy starting from the optical response of an individual molecule to incident femtosecond pump and probe pulses. The resulting description makes use of pulse propagators and free molecular evolution operators to arrive at compact expressions for the several contributions to a transient-absorption signal. In this alternative description, which is physically equivalent to the conventional response-function formalism, these signal contributions are conveniently expressed as quantum mechanical overlaps between nuclear wave packets that have undergone different sequences of pulse-driven optical transitions and time-evolution on different electronic potential-energy surfaces. Using this setup in application to a simple, multimode model of the light-harvesting chromophores of PC577, we develop wave-packet pictures of certain generic features of ultrafast transient-absorption signals related to the probed-frequency dependence of vibrational quantum beats. These include a Stokes-shifting node at the time-evolving peak emission frequency, antiphasing between vibrational oscillations on opposite sides (i.e., to the red or blue) of this node, and spectral fingering due to vibrational overtones and combinations. Our calculations make a vibrationally abrupt approximation for the incident pump and probe pulses, but properly account for temporal pulse overlap and signal turn-on, rather than neglecting pulse overlap or assuming delta-function excitations, as are sometimes done.

  17. Magnetic Field Sensing Based on Bi-Tapered Optical Fibers Using Spectral Phase Analysis.

    Science.gov (United States)

    Herrera-Piad, Luis A; Haus, Joseph W; Jauregui-Vazquez, Daniel; Sierra-Hernandez, Juan M; Estudillo-Ayala, Julian M; Lopez-Dieguez, Yanelis; Rojas-Laguna, Roberto

    2017-10-20

    A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF) span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data collection, we applied a phase analysis of the interference optical spectrum. We here report the results on two fabricated, BTOFs with different interference spectrum characteristics; we analyzed the signal based on the interference between a high-order modal component and the core fiber mode. The sensor exhibited a linear response for magnetic field increments, and we achieved a phase sensitivity of around 0.28 rad/mT. The sensing setup presented remote sensing operation and low-cost transducer magnetic material.

  18. Magnetic Field Sensing Based on Bi-Tapered Optical Fibers Using Spectral Phase Analysis

    Directory of Open Access Journals (Sweden)

    Luis A. Herrera-Piad

    2017-10-01

    Full Text Available A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data collection, we applied a phase analysis of the interference optical spectrum. We here report the results on two fabricated, BTOFs with different interference spectrum characteristics; we analyzed the signal based on the interference between a high-order modal component and the core fiber mode. The sensor exhibited a linear response for magnetic field increments, and we achieved a phase sensitivity of around 0.28 rad/mT. The sensing setup presented remote sensing operation and low-cost transducer magnetic material.

  19. Spectral descriptors for bulk metallic glasses based on the thermodynamics of competing crystalline phases

    OpenAIRE

    Perim, Eric; Lee, Dongwoo; Liu, Yanhui; Toher, Cormac; Gong, Pan; Li, Yanglin; Simmons, W. Neal; Levy, Ohad; Vlassak, Joost J.; Schroers, Jan; Curtarolo, Stefano

    2016-01-01

    Metallic glasses have attracted considerable interest in recent years due to their unique combination of superb properties and processability. Predicting bulk metallic glass formers from known parameters remains a challenge and the search for new systems is still performed by trial and error. It has been speculated that some sort of "confusion" during crystallization of the crystalline phases competing with glass formation could play a key role. Here, we propose a heuristic descriptor quantif...

  20. Une stratégie pour l'interprétation en analyse spectrale. Détection et caractérisation des composantes d'un spectre.

    OpenAIRE

    Durnerin , Matthieu

    1999-01-01

    This thesis intends to build an original process of spectral analysis of stationary signals. Its originality lies in the decision concept that we used. It is not based on the choice of one method for a particular signal, but on a methods comparison. The purpose of this comparison is to estimate the signal spectral structures. We use an iterative interpretation of the spectrum based on the properties of the analysis methods. A complete and detailed theoretical study of each selected Fourier's ...

  1. Multi-objective optimization for an automated and simultaneous phase and baseline correction of NMR spectral data

    Science.gov (United States)

    Sawall, Mathias; von Harbou, Erik; Moog, Annekathrin; Behrens, Richard; Schröder, Henning; Simoneau, Joël; Steimers, Ellen; Neymeyr, Klaus

    2018-04-01

    Spectral data preprocessing is an integral and sometimes inevitable part of chemometric analyses. For Nuclear Magnetic Resonance (NMR) spectra a possible first preprocessing step is a phase correction which is applied to the Fourier transformed free induction decay (FID) signal. This preprocessing step can be followed by a separate baseline correction step. Especially if series of high-resolution spectra are considered, then automated and computationally fast preprocessing routines are desirable. A new method is suggested that applies the phase and the baseline corrections simultaneously in an automated form without manual input, which distinguishes this work from other approaches. The underlying multi-objective optimization or Pareto optimization provides improved results compared to consecutively applied correction steps. The optimization process uses an objective function which applies strong penalty constraints and weaker regularization conditions. The new method includes an approach for the detection of zero baseline regions. The baseline correction uses a modified Whittaker smoother. The functionality of the new method is demonstrated for experimental NMR spectra. The results are verified against gravimetric data. The method is compared to alternative preprocessing tools. Additionally, the simultaneous correction method is compared to a consecutive application of the two correction steps.

  2. Culture du bambou : diversification des moyens de subsistance des ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Culture du bambou : diversification des moyens de subsistance des petits producteurs de tabac du sud de la province de Nyanza, au Kenya - phase II. Au cours de la première phase du projet (projet no 103765), les chercheurs ont effectué une analyse de marché pour le bambou et les produits du bambou, comparé les ...

  3. 640 Gbit/s return-to-zero to non-return-to-zero format conversion based on optical linear spectral phase filtering

    DEFF Research Database (Denmark)

    Maram, Reza; Kong, Deming; Galili, Michael

    2016-01-01

    We propose a novel approach for all-optical return-to-zero (RZ) to non-return-to-zero (NRZ) telecommunication data format conversion based on linear spectral phase manipulation of an RZ data signal. The operation principle is numerically analyzed and experimentally validated through successful fo...

  4. Radiative modeling and characterization of aerosol plumes hyper-spectral imagery; Modelisation radiative et caracterisation des panaches d'aerosols en imagerie hyperspectrale

    Energy Technology Data Exchange (ETDEWEB)

    Alakian, A

    2008-03-15

    This thesis aims at characterizing aerosols from plumes (biomass burning, industrial discharges, etc.) with hyper-spectral imagery. We want to estimate the optical properties of emitted particles and also their micro-physical properties such as number, size distribution and composition. To reach our goal, we have built a forward semi-analytical model, named APOM (Aerosol Plume Optical Model), which allows to simulate the radiative effects of aerosol plumes in the spectral range [0,4-2,5 {mu}m] for nadir viewing sensors. Mathematical formulation and model coefficients are obtained from simulations performed with the radiative transfer code COMANCHE. APOM is assessed on simulated data and proves to be accurate with modeling errors between 1% and 3%. Three retrieval methods using APOM have been developed: L-APOM, M-APOM and A-APOM. These methods take advantage of spectral and spatial dimensions in hyper-spectral images. L-APOM and M-APOM assume a priori knowledge on particles but can estimate their optical and micro-physical properties. Their performances on simulated data are quite promising. A-APOM method does not require any a priori knowledge on particles but only estimates their optical properties. However, it still needs improvements before being usable. On real images, inversion provides satisfactory results for plumes above water but meets some difficulties for plumes above vegetation, which underlines some possibilities of improvement for the retrieval algorithm. (author)

  5. Possibilities of gas-phase radio-chromatography application to permanent-gas analysis; Possibilites de la radiochromatographie en phase gazeuse applications a l'analyse des gaz permanents

    Energy Technology Data Exchange (ETDEWEB)

    Dupuis, M C; Charrier, G; Alba, C; Massimino, D [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1970-07-01

    The gas-phase radio-chromatography technique has been applied to the rapid analysis of permanent gases (H{sub 2}, O{sub 2}, N{sub 2}, A, Kr, Xe, CO, CH{sub 4}) labelled with radioactive indicators ({sup 3}H, {sup 37}A, {sup 85}Kr, {sup 133}Xe). After calibration, the components of such a mixture can be identified and their concentrations measured in less than two hours, using a sample volume of from 0.1 to 10 cm{sup 3}. The minimum detectable activity is of the order of 10{sup -4} {mu}C for each radioactive isotope. The measurements are reproducible to about 2 to 3 per cent. This work has been mainly concerned with the influence of parameters affecting the response of the radioactivity detector (ionization chamber or gas flow proportional counter). The method has very numerous applications both theoretically, for the study of chromatographic phenomena under ideal conditions (infinitesimal concentrations made possible by the use of radioactive tracers), and practically, for rapid and accurate radiochemical analysis of radioactive gas mixtures. (authors) [French] La technique de radiochromatographie en phase gazeuse est appliquee a l'analyse rapide de gaz permanents (H{sub 2}, O{sub 2}, N{sub 2}, A, Kr, Xe, CO, CH{sub 4}) marques par des indicateurs radioactifs ({sup 3}H, {sup 37}A, {sup 85}Kr, {sup 133}Xe). Apres etalonnage, l'identification et la mesure des concentrations des constituants d'un tel melange requierent moins de deux heures, sur un volume d'echantillon de 0.1 a 10 cm{sup 3}. L'activite minimum detectable est de l'ordre de 10{sup -4} {mu}C pour chaque isotope radioactif. La reproductibilite des mesures est de l'ordre de 2 a 3 pour cent. L'etude porte principalement sur l'influence des parametres affectant la reponse du detecteur de radioactivite (chambre d'ionisation, ou compteur proportionnel a circulation). La methode est extremement fertile en applications tant sur le plan theorique pour l'etude du phenomene chromatographique dans les conditions

  6. Possibilities of gas-phase radio-chromatography application to permanent-gas analysis; Possibilites de la radiochromatographie en phase gazeuse applications a l'analyse des gaz permanents

    Energy Technology Data Exchange (ETDEWEB)

    Dupuis, M.C.; Charrier, G.; Alba, C.; Massimino, D. [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1970-07-01

    The gas-phase radio-chromatography technique has been applied to the rapid analysis of permanent gases (H{sub 2}, O{sub 2}, N{sub 2}, A, Kr, Xe, CO, CH{sub 4}) labelled with radioactive indicators ({sup 3}H, {sup 37}A, {sup 85}Kr, {sup 133}Xe). After calibration, the components of such a mixture can be identified and their concentrations measured in less than two hours, using a sample volume of from 0.1 to 10 cm{sup 3}. The minimum detectable activity is of the order of 10{sup -4} {mu}C for each radioactive isotope. The measurements are reproducible to about 2 to 3 per cent. This work has been mainly concerned with the influence of parameters affecting the response of the radioactivity detector (ionization chamber or gas flow proportional counter). The method has very numerous applications both theoretically, for the study of chromatographic phenomena under ideal conditions (infinitesimal concentrations made possible by the use of radioactive tracers), and practically, for rapid and accurate radiochemical analysis of radioactive gas mixtures. (authors) [French] La technique de radiochromatographie en phase gazeuse est appliquee a l'analyse rapide de gaz permanents (H{sub 2}, O{sub 2}, N{sub 2}, A, Kr, Xe, CO, CH{sub 4}) marques par des indicateurs radioactifs ({sup 3}H, {sup 37}A, {sup 85}Kr, {sup 133}Xe). Apres etalonnage, l'identification et la mesure des concentrations des constituants d'un tel melange requierent moins de deux heures, sur un volume d'echantillon de 0.1 a 10 cm{sup 3}. L'activite minimum detectable est de l'ordre de 10{sup -4} {mu}C pour chaque isotope radioactif. La reproductibilite des mesures est de l'ordre de 2 a 3 pour cent. L'etude porte principalement sur l'influence des parametres affectant la reponse du detecteur de radioactivite (chambre d'ionisation, ou compteur proportionnel a circulation). La methode est extremement fertile en applications tant sur le plan theorique pour l

  7. Contribution to the study of the sintering mechanisms of uranium powders in the {alpha}, {beta}, and {gamma} phases; Contribution a l'etude des mecanismes de frittage de poudre d'uranium en phases {alpha}, {beta}, et {gamma}

    Energy Technology Data Exchange (ETDEWEB)

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

    1964-06-01

    also followed by simple and differential thermal analysis. (author) [French] L'etude des mecanismes de frittage de poudre d'uranium d'origine caliothermique a ete effectuee sous vide par mesure dilatometrique en continu des retraits d'echantillons prealablement comprimes a temperature ordinaire sous atmosphere d'argon purifie. Les essais effectues dans les trois domaines {alpha}, {beta}, {gamma} ont permis de constater que le premier stade de frittoge semble regi par un mecanisme d'autodiffusion en volume; les valeurs des chaleurs d'activation des mecanismes de frittage trouves sont voisines de celles deduites lors des etudes sur l'autodiffusion en volume par la methode directe des radiotraceurs. Par ailleurs, dans le domaine {gamma} on a pu mettre en evidence un second mecanisme de frittage qui interesse des durees de frittage beaucoup plus longues, a chaleur d'activation beaucoup plus faible semblant indiquer qu'il s'agit d'un mecanisme d'elimination des pores par diffusion intergranulaire de lacunes. En outre, les essois dilatometriques permettent de mettre en evidence l'influence simultanee de deux facteurs principaux regissant cette etude: les joints de grains et les coefficients de diffusion. Dans une seconde partie, les echantillons frittes ont ete etudies par diverses methodes afin de determiner leur structure et certaines de leurs proprietes physiques. C'est ainsi que des examens metallographiques effectues apres polissage par bombardement ionique ont permis de determiner l'evolution de la porosite dans les trois phases {alpha}, {beta} et {gamma} ainsi que la structure et la nature des inclusions dans chaque echantillon. Par ailleurs des mesures de densite et de porosite ont ete effectuees. L'evolution des deux series de resultats permet de confirmer les examens dilatometriques et micrographiques precedents. Enfin, une etude dilatometrique detaillee des echantillons frittes en phose {gamma} a permis de montrer l'influence des couches d'oxyde associees a la

  8. The peculiarities of spectral manifestations of high-voltage electric discharge in different phase states of ion systems.

    Science.gov (United States)

    Gafurov, M M; Aliev, A R; Ataev, M B; Rabadanov, K Sh

    2013-10-01

    The effects of high-voltage pulsed discharge (HVPD activation) on vibrational spectra of ion salt systems have been studied. The peculiarities of spectral display of HVPD in ion melts and aqueous solutions of electrolytes, in ion-conducting phases of crystalline and glassy salt systems have been investigated. After HVPD a salt system is in non-equilibrium activated state. In the activated state of a salt system, the relaxation time of the vibrational excited states of molecular ions is shorter than in the equilibrium state if the vibrational relaxation rate increases with temperature in the system. For those systems for which the relaxation rate decreases at elevated temperatures, the relaxation time of the vibrational excited states of molecular ions is longer than in the equilibrium state. HVPD activation of a salt system can change the configuration of the electron shell of molecular ions. Therefore, the lifetime values of activated state of salt systems are abnormally large. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. STRUCTURAL PHASE TRANSITION OF ALIPHATIC NYLONS VIEWED FROM THE WAXD/SAXS AND VIBRATIONAL SPECTRAL MEASUREMENTS AND MOLECULAR DYNAMICS CALCULATION

    Institute of Scientific and Technical Information of China (English)

    Kohji Tashiro

    2007-01-01

    The crystalline phase transition of aliphatic nylon 10/10 has been investigated on the basis of the simultaneous measurement of wide-angle and small-angle X-ray scatterings, the infrared spectral measurement and the molecular dynamics calculation. An interpretation of infrared spectra taken for a series of nylon samples and the corresponding model compounds was successfully made, allowing us to assign the infrared bands of the planar-zigzag methylene segments reasonably. As a result the methylene segmental parts of molecular chains were found to experience an order-to-disorder transition in the Brill transition region, where the intermolecular hydrogen bonds are kept alive although the bond strength becomes weaker at higher temperature. The small-angle X-ray scattering data revealed a slight change in lamellar stacking mode in the transition region. The crystal structure has been found to change more remarkably in the temperature region immediately below the melting point, where the conformationally disordered chains experienced drastic rotational and translational motions without any constraints by hydrogen bonds, and the lamellar thickness increased largely along the chain axis. These experimental results were reasonably reproduced by the molecular dynamics calculation performed at the various temperatures.

  10. Structure of two-phase air-water flows. Study of average void fraction and flow patterns; Structure des ecoulements diphasiques eau-air. Etude de la fraction de vide moyenne et des configurations d'ecoulement

    Energy Technology Data Exchange (ETDEWEB)

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

    1969-07-01

    This report deals with experimental work on a two phase air-water mixture in vertical tubes of different diameters. The average void fraction was measured in a 2 metre long test section by means of quick-closing valves. Using resistive probes and photographic techniques, we have determined the flow patterns and developed diagrams to indicate the boundaries between the various patterns: independent bubbles, agglomerated bubbles, slugs, semi-annular, annular. In the case of bubble flow and slug flow, it is shown that the relationship between the average void fraction and the superficial velocities of the phases is given by: V{sub sg} = f(<{alpha}>) * g(V{sub sl}). The function g(V{sub sl}) for the case of independent bubbles has been found to be: g(V{sub sl}) = V{sub sl} + 20. For semi-annular and annular flow conditions; it appears that the average void fraction depends, to a first approximation only on the ratio V{sub sg}/V{sub sl}. (author) [French] Ce rapport est une etude experimentale d'un melange diphasique eau-air dans des tubes verticaux de differents diametres. Nous avons mesure la fraction de vide moyenne dans une portion de canal de longueur 2 m, au moyen d'un systeme de vannes a fermeture rapide et simultanee. Au moyen de sondes resistives et de photographies nous avons determine la configuration de l'ecoulement et trace des cartes donnant les frontieres entre les differentes configurations d'ecoulement: bulles independantes, bulles agglomerees, bouchons, semi-annulaire, annulaire. Nous montrons que pour les regimes a bulles et a bouchons, une equation de la forme V{sub sg} = f(<{alpha}>) * g(V{sub sl}) relie la fraction de vide moyenne aux vitesses superficielles de chacune des phases. Nous avons pu determiner la fonction g(V{sub sl}) dans le cas du regime a bulles independantes, et nous trouvons g(V{sub sl}) = V{sub sl} + 20. Pour les regimes semi-annulaire et annulaire, il semble qu'en premiere approximation, la fraction de vide moyenne ne depende que

  11. Commission to review the financing for the phase-out of nuclear energy. Results, evaluation, implementation; Kommission zur Ueberpruefung der Finanzierung des Kernenergieausstiegs (KFK). Ergebnisse, Bewertung, Umsetzung

    Energy Technology Data Exchange (ETDEWEB)

    Brandmair, Lothar [Wirtschaftskanzlei Graf von Westphalen, Muenchen (Germany)

    2016-07-15

    The German Commission to Review the Financing for the Phase-out of Nuclear Energy (Kommission zur Ueberpruefung der Finanzierung des Kernenergieausstiegs, KFK) has unanimously adopted its report on 27 April 2016. Now the Federal Government is working on the implementation of the recommendations, which are directed to profound changes in the present system of financing and action responsibilities of government and operators. The proposals by KFK on their meaning and scope are described and analyzed. An overview of the tasks to implement the recommendations at the legislative and contractual level is given. The work of KFK is also classified in its social context and assessed as a viable compromise.

  12. Detection of burst cans in the reactors cooled by gaseous phase; Detection des ruptures de gaine dans les reacteurs refroidis par phase gazeuse

    Energy Technology Data Exchange (ETDEWEB)

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

    1955-07-01

    In a nuclear reactor including the bars or plates cooled by a gaseous fluid, burst risks to occur in the sheath assuring the tightness separation between the cooling gas and the fissile materials. It is necessary to be able to detect the formation of these cracks as possible in order to avoid all risk of fission products release or any reaction of uranium to the contact of the refrigerating gas. It is however the increase of the radioactivity in the cooling gas due to the scattering of the fission products that permits to signal the apparition of a crack or to follow its evolution. It is possible to detect cracks of the order of the square millimeter. In this report, we will detail the principle and the realization of a device used for the surveillance of a natural uranium reactor cooled by air circulation. (M.B.) [French] Dans un reacteur nucleaire comportant des barres ou des plaques refroidies par un fluide gazeux des fissures risquent de se produire dans les gaines assurant la separation etanche entre le gaz de refroidissement et les materiaux fissiles. II est necessaire de pouvoir detecter la formation de ces fissures des que possible afin d'eviter tout risque de liberation de produits de fission ou de reaction de l'uranium au contact du gaz refrigerant. C'est cependant l'augmentation de la radioactivite du gaz de refroidissement due a la dispersion des produits de fission qui permet de signaler l'apparition d'une fissure ou de suivre son evolution. On peut ainsi detecter des fissures de l'ordre du millimetre carre. Dans ce rapport, nous detaillerons le principe et la realisation d'un appareil utilise pour la surveillance d'un reacteur a uranium naturel refroidi par circulation d'air. (M.B.)

  13. Séparations par changement de phase. Etude et représentation des équilibres liquide-vapeur Separation by Phase Hange. Study and Computing Liquid-Vapor Equilibria

    Directory of Open Access Journals (Sweden)

    Asselineau L.

    2006-11-01

    Full Text Available Pour concevoir et optimiser les principales opérations de séparation (particulièrement les distillations avec ou sans solvant et l'extraction liquide-liquide on doit disposer de méthodes de corrélation ou, mieux, de prédiction des équilibres entre phases. A basse pression, et pour les mélanges d'hydrocarbures, les résultats présentés permettent la prévision des coefficients d'équilibre, même pour les séparations les plus délicates. En présence de constituants polaires, les données expérimentales d'équilibre liquide-liquide et liquide-vapeur de mélanges binaires et ternaires peuvent être simultanément corrélées dans le but de simuler et d'optimiser les distillations azéotropiques ou extractives. Sous haute pression, et particulièrement aux abords immédiats du point critique, le choix d'une équation d'état conduit à un traitement unitaire des phases en présence et permet, en particulier, la prédiction du lieu des points critiques des mélanges d'hydrocarbures et la corrélation de ce lieu en présence de solvants polaires. To determine and optimize the main separation operations (in particular distillations with or without a solvent, and liquid-liquid extraction correlation methods must be available or, better yet, methods of predicting phase equilibria. At low pressure and for hydrocarbon mixtures, the results described make the prediction of equilibrium coefficients possible, even for the most delicate separation. In the presence of polar constituents, the experimental data for the liquid-liquid and liquid-vapor equilibrium of binary and ternary mixtures can be simultaneously correlaten so as to simulate and optimize azeotropic or extractive distillations. Under high pressure and especially in the immediate vicinityof the critical point, the choice of an equation of state leads ta a unit treatment of the phases present and, in particular, makes it possible to predict the location of critical points in hydrocarbon

  14. Towards Eulerian-Eulerian large eddy simulation of reactive two-phase plows; Vers la simulation des grandes echelles en formulation Euler-Euler des ecoulements reactifs diphasiques

    Energy Technology Data Exchange (ETDEWEB)

    Kaufmann, A.

    2004-03-15

    Particle laden flows occur in industrial applications ranging from droplets in gas turbines to fluidized bed in chemical industry. Prediction of the dispersed phase properties such as concentration and dynamics are crucial for the design of more efficient devices that meet the new pollutant regulations of the European community. Numerical simulation coupling Lagrangian tracking of discrete particles with DNS or LES of the carrier phase provide a well established powerful tool to investigate particle laden flows. Such numerical methods have the drawback of being numerically very expensive for practical applications. Numerical simulations based on separate Eulerian balance equations for both phases, coupled through inter-phase exchange terms might be an effective alternative approach. This approach has been validated for the case of tracer particles with very low inertia that follow the carrier phase almost instantaneously due to their small response time compared with the micro-scale time scales of the carrier phase. Objective of this thesis is to extend this approach to more inertial particles that occur in practical applications such as fuel droplets in gas turbine combustors. Existing results suggest a separation of the dispersed phase velocity into a correlated and an uncorrelated component. The energy related to the uncorrelated component is about 30% of the total particle kinetic energy when the particle relaxation time is comparable to the Lagrangian integral time scale. The presence of this uncorrelated motion leads to stress terms in the Eulerian balance equation for the particle momentum. Models for this stress terms are proposed and tested. Numerical simulations in the Eulerian framework are validated by comparison with simulations using Lagrangian particle tracking. Additionally coupling of the Eulerian transport equations for the particles to combustion models is tested. (author)

  15. Correlation and Prediction of Phase Equilibria and Volumetric Behaviour of Hyperbaric Binary Fluids Corrélation et prédiction des équilibres de phases et du comportement volumétrique de fluides hyperbares binaires

    Directory of Open Access Journals (Sweden)

    Stamataki S. K.

    2006-11-01

    Full Text Available The capabilities of cubic Equations of State (EoS in the correlation and the prediction of phase equilibria at hyperbaric conditions is examined. PVT data of pure compounds as well as VLE and volumetric data of binary mixtures up to 2000 bar are used. Correlation and prediction results are presented with the translated and modified Peng-Robinson (t - mPR EoS and EoS/GE models. The performance of cubic EoS with a single interaction parameter (kij in describing VLE is remarkable considering the level of pressures involved. The same is valid for the PVT results including the relative liquid volumes of the C1/nC24 system. With typical errors of about 10% deviations in pressure of 100 - 200 bar are, of course, encountered which can be eliminated by the use of second interaction coefficient in the covolume combining rule. Predicted kij values obtained from generalized correlations developed from low pressure VLE data provide reasonable results for systems with hydrocarbons up to nC16 even at high pressures, but fail for higher asymmetric ones. Volume translation is essential for PVT predictions. The temperature independent translation of t - mPR and that of Jhaveri and Yougren give very satisfactory results. LCVM provides the best results of the EoS/GE models studied and gives very good predictions for rather symmetric systems which become poorer with asymmetric ones at very high pressures. La capacité des équations d'état (EoS cubiques pour corréler et prédire les équilibres de phases en conditions hyperbares est analysée. Les données PVT de corps purs ainsi que les données d'équilibres liquide-vapeur (VLE et volumétriques pour des mélanges binaires, jusqu'à 2000 bar sont utilisées. Les résultats des corrélations et des prédictions sont présentés pour l'équation de Peng-Robinson translatée et modifiée (t - mPR, ainsi que pour les modèles EoS/GE. Les performances des EoS cubiques avec un paramètre d'interaction unique (kij pour

  16. Influence of heat treatment in {beta} and {gamma} phases on the microscopic structure of uranium; Influence des traitements thermiques en phases {beta} et {gamma} sur la structure micrographique de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Robillard, A

    1958-06-02

    'orientation den structures polygonisees. En utilisant cette technique d'examen on a montre l'existence de sous-structures, differentes de celles dues a la polygonisation de la phase {alpha}, dans l'uranium traite en phase {gamma} et refroidi a une vitesse qui depend de la temperature de maintien en {gamma}. ces sous-structures sont materialisees par la precipitation d'impuretes sur les dislocations induites par les tensions qui accompagnent la transformation {gamma} {yields} {beta}. Des traitements analogues sur un alliage U-Cr 1,4 % ou la phase {beta} peut etre retenue a la temperature ambiante, confirme cette explication. En plus de ces sous-structures, on observe dans le reseau des discontinuites formant un reseau de 'joints blancs'. La comparaison avec les structures revelees par attaque thermique indique qu'il s'agit des traces des joints de la phase {gamma}. La methode d''attaque-oxydation' a permis la mise en evidence d'une phase 'aureolee' identifiee comme etant UH{sub 3}. Les conditions d'apparition et de disparition de cette phase sont etudiees. La sensibilite de la methode a detecter les traces ultimes d'H dans U est tres grande. On a enfin etudie l'influence de la teneur en hydrogene sur les proprietes mecaniques du metal uranium. (auteur)

  17. Influence of heat treatment in {beta} and {gamma} phases on the microscopic structure of uranium; Influence des traitements thermiques en phases {beta} et {gamma} sur la structure micrographique de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Robillard, A

    1958-06-02

    aux faibles variations d'orientation den structures polygonisees. En utilisant cette technique d'examen on a montre l'existence de sous-structures, differentes de celles dues a la polygonisation de la phase {alpha}, dans l'uranium traite en phase {gamma} et refroidi a une vitesse qui depend de la temperature de maintien en {gamma}. ces sous-structures sont materialisees par la precipitation d'impuretes sur les dislocations induites par les tensions qui accompagnent la transformation {gamma} {yields} {beta}. Des traitements analogues sur un alliage U-Cr 1,4 % ou la phase {beta} peut etre retenue a la temperature ambiante, confirme cette explication. En plus de ces sous-structures, on observe dans le reseau des discontinuites formant un reseau de 'joints blancs'. La comparaison avec les structures revelees par attaque thermique indique qu'il s'agit des traces des joints de la phase {gamma}. La methode d''attaque-oxydation' a permis la mise en evidence d'une phase 'aureolee' identifiee comme etant UH{sub 3}. Les conditions d'apparition et de disparition de cette phase sont etudiees. La sensibilite de la methode a detecter les traces ultimes d'H dans U est tres grande. On a enfin etudie l'influence de la teneur en hydrogene sur les proprietes mecaniques du metal uranium. (auteur)

  18. The use of phase modulation optimization for power lasers. Minimizing the FM-AM conversion while preserving spectral broadening functionalities required for fusion

    International Nuclear Information System (INIS)

    Hocquet, St.

    2009-11-01

    This research thesis deals with the problem of phase modulations in power lasers (such as the MegaJoule laser which is developed in France) and their impact of different physical phenomena like the suppression of the stimulated Brillouin scattering (which is necessary to avoid optics damage) and the optical smoothing which allows a spatial homogenisation of focal stains. The author deeply discusses the phase modulation counterparts, and more particularly the FM-AM conversion which is the source of unwanted intensity modulation and of energy loss. He reports the development of a comprehensive modelling of phenomena generating FM-AM conversion on a power laser chain. He theoretically and experimentally studies two methods allowing the FM-AM conversion to be reduced to a given spectral distortion: the compensation of transfer functions and the modification of the phase modulation signal to make it less sensitive to spectral distortion effects. For this last method, he determines the ideal spectrum shape for the phase modulation, and proposes a method to approach it. He shows the feasibility of such a method and reports experiments showing to which extent these solutions may improve performance of power lasers. Finally, he proposed optimised solutions for the MegaJoule Laser

  19. Spectral dependence of backscattering coefficient of mixed phase clouds over West Africa measured with two-wavelength Raman polarization lidar: Features attributed to ice-crystals corner reflection

    Science.gov (United States)

    Veselovskii, I.; Goloub, P.; Podvin, T.; Tanre, D.; Ansmann, A.; Korenskiy, M.; Borovoi, A.; Hu, Q.; Whiteman, D. N.

    2017-11-01

    The existing models predict that corner reflection (CR) of laser radiation by simple ice crystals of perfect shape, such as hexagonal columns or plates, can provide a significant contribution to the ice cloud backscattering. However in real clouds the CR effect may be suppressed due to crystal deformation and surface roughness. In contrast to the extinction coefficient, which is spectrally independent, consideration of diffraction associated with CR results in a spectral dependence of the backscattering coefficient. Thus measuring the spectral dependence of the cloud backscattering coefficient, the contribution of CR can be identified. The paper presents the results of profiling of backscattering coefficient (β) and particle depolarization ratio (δ) of ice and mixed-phase clouds over West Africa by means of a two-wavelength polarization Mie-Raman lidar operated at 355 nm and 532 nm during the SHADOW field campaign. The lidar observations were performed at a slant angle of 43 degree off zenith, thus CR from both randomly oriented crystals and oriented plates could be analyzed. For the most of the observations the cloud backscatter color ratio β355/β532 was close to 1.0, and no spectral features that might indicate the presence of CR of randomly oriented crystals were revealed. Still, in two measurement sessions we observed an increase of backscatter color ratio to a value of nearly 1.3 simultaneously with a decrease of the spectral depolarization ratio δ355/δ532 ratio from 1.0 to 0.8 inside the layers containing precipitating ice crystals. We attribute these changes in optical properties to corner reflections by horizontally oriented ice plates.

  20. Understanding Soliton Spectral Tunneling as a Spectral Coupling Effect

    DEFF Research Database (Denmark)

    Guo, Hairun; Wang, Shaofei; Zeng, Xianglong

    2013-01-01

    Soliton eigenstate is found corresponding to a dispersive phase profile under which the soliton phase changes induced by the dispersion and nonlinearity are instantaneously counterbalanced. Much like a waveguide coupler relying on a spatial refractive index profile that supports mode coupling...... between channels, here we suggest that the soliton spectral tunneling effect can be understood supported by a spectral phase coupler. The dispersive wave number in the spectral domain must have a coupler-like symmetric profile for soliton spectral tunneling to occur. We show that such a spectral coupler...

  1. Contrast Dose and Radiation Dose Reduction in Abdominal Enhanced Computerized Tomography Scans with Single-phase Dual-energy Spectral Computerized Tomography Mode for Children with Solid Tumors.

    Science.gov (United States)

    Yu, Tong; Gao, Jun; Liu, Zhi-Min; Zhang, Qi-Feng; Liu, Yong; Jiang, Ling; Peng, Yun

    2017-04-05

    Contrast dose and radiation dose reduction in computerized tomography (CT) scan for adult has been explored successfully, but there have been few studies on the application of low-concentration contrast in pediatric abdominal CT examinations. This was a feasibility study on the use of dual-energy spectral imaging and adaptive statistical iterative reconstruction (ASiR) for the reduction of radiation dose and iodine contrast dose in pediatric abdominal CT patients with solid tumors. Forty-five patients with solid tumors who had initial CT (Group B) and follow-up CT (Group A) after chemotherapy were enrolled. The initial diagnostic CT scan (Group B) was performed using the standard two-phase enhanced CT with 320 mgI/ml concentration contrast, and the follow-up scan (Group A) was performed using a single-phase enhanced CT at 45 s after the beginning of the 270 mgI/ml contrast injection using spectral mode. Forty percent ASiR was used for the images in Group B and monochromatic images with energy levels ≥60 keV in Group A. In addition, filtered back-projection (FBP) reconstruction was used for monochromatic images hounsfield unit (HU). The abdominal organs of Groups A and B had similar degrees of absolute and relative enhancement (t = 0.36 and -1.716 for liver, -0.153 and -1.546 for pancreas, and 2.427 and 0.866 for renal cortex, all P> 0.05). Signal-to-noise ratio of the abdominal organs was significantly lower in Group A than in Group B (t = -8.11 for liver, -7.83 for pancreas, and -5.38 for renal cortex, all P 3, indicating clinically acceptable image quality. Single-phase, dual-energy spectral CT used for children with solid abdominal tumors can reduce contrast dose and radiation dose and can also maintain clinically acceptable image quality.

  2. Impact of the spectral and spatial properties of natural light on indoor gas-phase chemistry: Experimental and modeling study.

    Science.gov (United States)

    Blocquet, M; Guo, F; Mendez, M; Ward, M; Coudert, S; Batut, S; Hecquet, C; Blond, N; Fittschen, C; Schoemaecker, C

    2018-05-01

    The characteristics of indoor light (intensity, spectral, spatial distribution) originating from outdoors have been studied using experimental and modeling tools. They are influenced by many parameters such as building location, meteorological conditions, and the type of window. They have a direct impact on indoor air quality through a change in chemical processes by varying the photolysis rates of indoor pollutants. Transmittances of different windows have been measured and exhibit different wavelength cutoffs, thus influencing the potential of different species to be photolysed. The spectral distribution of light entering indoors through the windows was measured under different conditions and was found to be weakly dependent on the time of day for indirect cloudy, direct sunshine, partly cloudy conditions contrary to the light intensity, in agreement with calculations of the transmittance as a function of the zenithal angle and the calculated outdoor spectral distribution. The same conclusion can be drawn concerning the position within the room. The impact of these light characteristics on the indoor chemistry has been studied using the INCA-Indoor model by considering the variation in the photolysis rates of key indoor species. Depending on the conditions, photolysis processes can lead to a significant production of radicals and secondary species. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Numerical analysis of the harmonic components of the Bragg wavelength content in spectral responses of apodized fiber Bragg gratings written by means of a phase mask with a variable phase step height.

    Science.gov (United States)

    Osuch, Tomasz

    2016-02-01

    The influence of the complex interference patterns created by a phase mask with variable diffraction efficiency in apodized fiber Bragg grating (FBGs) formation on their reflectance spectra is studied. The effect of the significant contributions of the zeroth and higher (m>±1) diffraction orders on the Bragg wavelength peak and its harmonic components is analyzed numerically. The results obtained for Gaussian and tanh apodization profiles are compared with similar data calculated for a uniform grating. It is demonstrated that when an apodized FBG is written using a phase mask with variable diffraction efficiency, significant enhancement of the harmonic components and a reduction of the Bragg wavelength peak in the grating spectral response are observed. This is particularly noticeable for the Gaussian apodization profile due to the substantial contributions of phase mask sections with relatively small phase steps in the FBG formation.

  4. Simple and fast spectral domain algorithm for quantitative phase imaging of living cells with digital holographic microscopy

    Science.gov (United States)

    Min, Junwei; Yao, Baoli; Ketelhut, Steffi; Kemper, Björn

    2017-02-01

    The modular combination of optical microscopes with digital holographic microscopy (DHM) has been proven to be a powerful tool for quantitative live cell imaging. The introduction of condenser and different microscope objectives (MO) simplifies the usage of the technique and makes it easier to measure different kinds of specimens with different magnifications. However, the high flexibility of illumination and imaging also causes variable phase aberrations that need to be eliminated for high resolution quantitative phase imaging. The existent phase aberrations compensation methods either require add additional elements into the reference arm or need specimen free reference areas or separate reference holograms to build up suitable digital phase masks. These inherent requirements make them unpractical for usage with highly variable illumination and imaging systems and prevent on-line monitoring of living cells. In this paper, we present a simple numerical method for phase aberration compensation based on the analysis of holograms in spatial frequency domain with capabilities for on-line quantitative phase imaging. From a single shot off-axis hologram, the whole phase aberration can be eliminated automatically without numerical fitting or pre-knowledge of the setup. The capabilities and robustness for quantitative phase imaging of living cancer cells are demonstrated.

  5. Adaptive Spectral Doppler Estimation

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2009-01-01

    . The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to pro- vide good spectral resolution and contrast even when the ob- servation window is very short. The 2 adaptive techniques are tested......In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence...... and compared with the averaged periodogram (Welch’s method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set...

  6. Characterization of weakly absorbing thin films by multiple linear regression analysis of absolute unwrapped phase in angle-resolved spectral reflectometry.

    Science.gov (United States)

    Dong, Jingtao; Lu, Rongsheng

    2018-04-30

    The simultaneous determination of t, n(λ), and κ(λ) of thin films can be a tough task for the high correlation of fit parameters. The strong assumptions about the type of dispersion relation are commonly used as a consequence to alleviate correlation concerns by reducing the free parameters before the nonlinear regression analysis. Here we present an angle-resolved spectral reflectometry for the simultaneous determination of weakly absorbing thin film parameters, where a reflectance interferogram is recorded in both angular and spectral domains in a single-shot measurement for the point of the sample being illuminated. The variations of the phase recovered from the interferogram as functions of t, n, and κ reveals that the unwrapped phase is monotonically related to t, n, and κ, thereby allowing the problem of correlation to be alleviated by multiple linear regression. After removing the 2π ambiguity of the unwrapped phase, the merit function based on the absolute unwrapped phase performs a 3D data cube with variables of t, n and κ at each wavelength. The unique solution of t, n, and κ can then be directly determined from the extremum of the 3D data cube at each wavelength with no need of dispersion relation. A sample of GaN thin film grown on a polished sapphire substrate is tested. The experimental data of t and [n(λ), κ(λ)] are confirmed by the scanning electron microscopy and the comparison with the results of other related works, respectively. The consistency of the results shows the proposed method provides a useful tool for the determination of the thickness and optical constants of weakly absorbing thin films.

  7. Performance Analysis of Spectral-Phase-Encoded Optical CDMA System Using Two-Photon-Absorption Receiver Structure for Asynchronous and Slot-Level Synchronous Transmitters

    Science.gov (United States)

    Jamshidi, Kambiz; Salehi, Jawad A.

    2007-06-01

    In this paper, we analyze the performance of a nonlinear two-photon-absorption (TPA) receiver and compare its performance with that of a single-photon-absorption (SPA) receiver in the context of spectral-phase-encoded optical code-division multiple access (CDMA) technique. The performances for the above systems are evaluated for two different transmission scenarios, namely, asynchronous and slot-level synchronous transmitters. Performance evaluation includes different sources of degradation such as multiple-access interference, noise due to optical amplification, shot noise, and thermal noise. In obtaining the performance, the mean and variance of the received signal in each of the above techniques are derived, and bit error rate is obtained using Gaussian approximation. In general, it is shown that TPA receivers are superior in performance with respect to SPA receivers when the receiver employs a much slower photodetector in comparison with the laser's transmitted pulse duration. This, indeed, is the reason behind the choice of nonlinear receivers, such as TPA, in most spectral-phase-encoded optical CDMA systems.

  8. Curvature Effect and the Spectral Softening Phenomenon Detected ...

    Indian Academy of Sciences (India)

    soft spectral evolution, indicating that this spectral softening is not a rare phenomenon .... of time, there exists a temporal steep decay phase accompanied by spectral softening. (d) In most cases, the temporal power law index α and the spectral.

  9. Cumulative-Phase-Alteration of Galactic-Light Passing Through the Cosmic-Microwave-Background: A New Mechanism for Some Observed Spectral-Shifts

    Directory of Open Access Journals (Sweden)

    Tank H. K.

    2012-07-01

    Full Text Available Currently, whole of the measured “cosmological-red-shift ” is interpreted as due to the “metric-expansion-of-space”; so for the required “closer -density” of the universe, we need twenty times more mass-energy than the visible baryonic-matter contained in the universe. This paper proposes a new mechanism, which can account for good per- centage of the red-shift in the extra-galactic-light, greatly reducing the requirement of dark matter-energy. Also, this mechanism can cause a new kin d of blue-shift reported here, and their observational evidences. These spectral-s hifts are proposed to result due to cumulative phase-alteration of extra-galactic-light b ecause of vector-addition of: (i electric-field of extra-galactic-light and (ii that of the cosmic-microwave-background (CMB. Since the center-frequency of CMB is much lower than extra-galactic-light, the cumulative-phase-alteration results in red -shift, observed as an additional contribu- tor to the measured “cosmological red-shift”; and since the center-frequency of CMB is higher than the radio-frequency-signals used to measure velocity of space-probes like: Pioneer-10, Pioneer-11, Galileo and Ulysses, the cum ulative-phase-alteration re- sulted in blue-shift, leading to the interpretation of deceleration of these space-probes. While the galactic-light experiences the red-shift, and th e ranging-signals of the space- probes experience blue -shift, they are comparable in magnitude, providing a supportive- evidence for the new mechanism proposed here. More confirmative-experiments for this new mechanism are also proposed.

  10. Spectral analysis and quantum chemical studies of chair and twist-boat conformers of cycloheximide in gas and solution phases

    Science.gov (United States)

    Tokatli, A.; Ucun, F.; Sütçü, K.; Osmanoğlu, Y. E.; Osmanoğlu, Ş.

    2018-02-01

    In this study the conformational behavior of cycloheximide in the gas and solution (CHCl3) phases has theoretically been investigated by spectroscopic and quantum chemical properties using density functional theory (wB97X-D) method with 6-31++G(d,p) basis set, for the first time. The calculated IR results reveal that in the ground state the molecule exits as a mixture of the chair and twist-boat conformers in the gas phase, while the calculated NMR results reveal that it only exits as the chair conformer in the solution phase. In order to obtain the contributions coming from intramolecular interactions to the stability of the conformers in the gas and solution phases, the quantum theory of atoms in molecules (QTAIM), noncovalent interactions (NCI) method, and natural bond orbital analysis (NBO) have been employed. The QTAIM and NCI methods indicated that by intramolecular interactions with bond critical point (BCP) the twist-boat conformer is more stabilized than the chair conformer, while by steric interactions it is more destabilized. Considering that these interactions balance each other, the stabilities of the conformers are understood to be dictated by the van der Waals interactions. The NBO analyses show that the hyperconjugative and steric effects play an important role in the stabilization in the gas and solution phases. Furthermore, to get a better understanding of the chemical behavior of this important antibiotic drug we have evaluated and, commented the global and local reactivity descriptors of the both conformers. Finally, the EPR analysis of γ-irradiated cycloheximide has been done. The comparison of the experimental and calculated data have showed the inducement of a radical structure of (CH2)2ĊCH2 in the molecule. The experimental EPR spectrum has also confirmed that the molecule simultaneously exists in the chair and twist-boat conformers in the solid phase.

  11. Bit-rate-transparent optical RZ-to-NRZ format conversion based on linear spectral phase filtering

    DEFF Research Database (Denmark)

    Maram, Reza; Da Ros, Francesco; Guan, Pengyu

    2017-01-01

    We propose a novel and strikingly simple design for all-optical bit-rate-transparent RZ-to-NRZ conversion based on optical phase filtering. The proposed concept is experimentally validated through format conversion of a 640 Gbit/s coherent RZ signal to NRZ signal.......We propose a novel and strikingly simple design for all-optical bit-rate-transparent RZ-to-NRZ conversion based on optical phase filtering. The proposed concept is experimentally validated through format conversion of a 640 Gbit/s coherent RZ signal to NRZ signal....

  12. Orientational relationships between phases in the {gamma}{yields}{alpha} transformations for uranium-molybdenum alloys; Relations d'orientation entre phases dans les transformations {gamma}{yields}{alpha} des alliages uranium-molybdene

    Energy Technology Data Exchange (ETDEWEB)

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

    1966-04-01

    A crystallographic study has been made of the {gamma} {yields} {alpha} + {gamma} transformation in the alloy containing 3 per cent by weight of molybdenum using electronic micro-diffraction; it has been possible to establish the orientational relationships governing the germination of the {alpha} phase in the {gamma} phase. One finds: (111){gamma} // (100) {alpha}, (112-bar){gamma} // (010) {alpha}, (11-bar 0){gamma} // (001){alpha}. By choosing a monoclinic lattice containing the same number of atoms as the orthorhombic lattice for defining the {gamma} mother phase, the change in structure has been explained by adding a homogeneous (112-bar){gamma} [111]{gamma} shearing deformation to a heterogeneous deformation brought about by slipping of the atoms which are not situated at the nodes of this lattice. The identity of the orientation relationships {gamma}/{alpha} and {gamma}/{alpha}''b and the loss of coherence {gamma} /{alpha} as a function of temperature or of time lead to the conclusion that, in the range studied, the {gamma} {yields} {alpha} transformation begins with a martensitic process and continues by germination and growth. (author) [French] Une etude cristallographique de la transformation {gamma} {yields} {alpha} + {gamma} dans l'alliage {alpha} 3 pour cent en poids de Mo, effectuee par microdiffraction electronique a permis d'etablir les relations d'orientation regissant la germination de {alpha} dans {gamma}. On a: (111){gamma} // (100){alpha}, (112-bar){gamma} // (010){alpha}, (11-bar 0){gamma} // (001){alpha}. En choisissant pour decrire la phase mere {gamma} une maille monoclinique contenant le meme nombre d'atomes que la maille orthorhombique {alpha}, le changement de structure a ete explique en superposant a une deformation homogene par cisaillement (112-bar){gamma} [111]{gamma} une deformation heterogene par glissement des atomes non situes aux noeuds de cette maille. L identite des relations d'orientation {gamma}/{alpha} et {gamma} /{alpha

  13. Numerical simulation of two phase flows in heat exchangers; Simulation numerique des ecoulements diphasiques dans les echangeurs

    Energy Technology Data Exchange (ETDEWEB)

    Grandotto Biettoli, M

    2006-04-15

    The report presents globally the works done by the author in the thermohydraulic applied to nuclear reactors flows. It presents the studies done to the numerical simulation of the two phase flows in the steam generators and a finite element method to compute these flows. (author)

  14. Dosage simultané des acides sorbique et benzoïque dans les vins par chromatographie en phase gazeuse

    Directory of Open Access Journals (Sweden)

    F. Ureta

    1984-12-01

    Dans ce travail nous décrivons une méthode par chromatographie en phase gazeuse sur colonne capillaire qui permet en une seule opération de déterminer les acides benzoïque et sorbique dans les vins.

  15. Etude de la dynamique en régimes quasiharmonique et anharmonique de la phase basse température de la triéthylènediamine par diffusion cohérente inélastique des neutrons

    OpenAIRE

    Hedoux , A.; Sauvajol , J.L.; More , M.

    1988-01-01

    La triéthylènediamine N(CH2CH2)3N cristallise jusqu'à Tc = 351 K dans une phase solide ordonnée de symétrie hexagonale compacte. Les expériences de diffusion cohérente inélastique des neutrons réalisées dans la phase basse température s'inscrivent dans le cadre de l'étude du processus de la transition martensitique à Tc à partir de l'évolution avec la température des paramètres dynamiques. Ainsi les courbes de dispersion ont été déterminées à 190 K, 245 K et 295 K. Les mesures effectuées à te...

  16. L-H bifurcations as phase transitions, the role of zonal flows and the spectral energy transfer

    International Nuclear Information System (INIS)

    Shats, M.G.; Punzmann, H.; Xia, H.; Solomon, W.M.

    2003-01-01

    An overview of new results related to the physics of confinement bifurcations in the H-1 heliac is presented. A macroscopic description of the transport modifications across L-H transitions in H-1 suggests several analogies between these bifurcations and phase transitions. Among them is the nucleation in phase transitions which is manifested in the plasma both in time and in space. A microscopic picture reveals the importance of zonal flows, or time-varying shear radial electric field in the spatio-temporal structure of confinement bifurcations. In particular, the effect of zonal flows on the fluctuation-driven transport in H-1 is discussed. Finally, new results on the mechanism of generation of large coherent structures and zonal flows are reviewed. It is shown that inverse energy cascades in turbulent spectra are responsible for the structure generation in H-1. (orig.)

  17. Performance analysis of spectral-phase-encoded optical code-division multiple-access system regarding the incorrectly decoded signal as a nonstationary random process

    Science.gov (United States)

    Yan, Meng; Yao, Minyu; Zhang, Hongming

    2005-11-01

    The performance of a spectral-phase-encoded (SPE) optical code-division multiple-access (OCDMA) system is analyzed. Regarding the incorrectly decoded signal (IDS) as a nonstationary random process, we derive a novel probability distribution for it. The probability distribution of the IDS is considered a chi-squared distribution with degrees of freedom r=1, which is more reasonable and accurate than in previous work. The bit error rate (BER) of an SPE OCDMA system under multiple-access interference is evaluated. Numerical results show that the system can sustain very low BER even when there are multiple simultaneous users, and as the code length becomes longer or the initial pulse becomes shorter, the system performs better.

  18. Absolute measurement of subnanometer scale vibration of cochlear partition of an excised guinea pig cochlea using spectral-domain phase-sensitive optical coherence tomography

    Science.gov (United States)

    Subhash, Hrebesh M.; Choudhury, Niloy; Jacques, Steven L.; Wang, Ruikang K.; Chen, Fangyi; Zha, Dingjun; Nuttall, Alfred L.

    2012-01-01

    Direct measurement of absolute vibration parameters from different locations within the mammalian organ of Corti is crucial for understanding the hearing mechanics such as how sound propagates through the cochlea and how sound stimulates the vibration of various structures of the cochlea, namely, basilar membrane (BM), recticular lamina, outer hair cells and tectorial membrane (TM). In this study we demonstrate the feasibility a modified phase-sensitive spectral domain optical coherence tomography system to provide subnanometer scale vibration information from multiple angles within the imaging beam. The system has the potential to provide depth resolved absolute vibration measurement of tissue microstructures from each of the delay-encoded vibration images with a noise floor of ~0.3nm at 200Hz.

  19. Spectral Analysis of Instantaneous Power in Single-phase and Three-phase Systems with Use of p-q-r Theory

    DEFF Research Database (Denmark)

    Kim, Hyosung; Blaabjerg, Frede; Bak-Jensen, Birgitte

    2002-01-01

    This paper proposes a novel power compensation algorithm in three-phase four-wire systems by using p-q-r theory. The p-q-r theory is compared with two previous instantaneous power theories, p-q theory and cross-vector theory. The p-q-r theory provides two-degrees of freedom to control the system...

  20. Studies of neo-formed phases occurring during spent nuclear fuel dissolution in geological repository: influence of silicate ions; Etude des phases neoformees lors de la dissolution du combustible nucleaire en condition de stockage geologique: influence des ions silicate

    Energy Technology Data Exchange (ETDEWEB)

    Robit-Pointeau, V

    2005-12-15

    Spent nuclear fuel alteration in deep storage conditions may proceed by local oxidising conditions at the fuel / water interface under influence of alpha irradiation. However, due to the strong redox buffer capacity of the near-field materials (especially the canister and the geological media), most of the near-field environment will remain reducing. Due to the relative high concentration in silica in such system, coffinite USiO{sub 4}.n(H{sub 2}O) may be a relevant phase to consider as it has been suggested from the natural analogues observations (Oklo). The aim of this work was to assess the relevance of coffinitisation of the spent fuel phenomena. The results of the experimental work contest the thermodynamic predictions. Instead of coffinite, a new U(IV)-Si phase has been observed in water simulating storage conditions. The thermodynamic data on coffinite validated by OECD are based on the average concentration of dissolved silica present in natural system containing uraninite and quartz. As the silica concentration in natural groundwaters is more probably controlled by minerals like chalcedony or silica gel, the coffinite present with uraninite in such systems, is probably not in equilibrium even in 2-billion years- old geological sites. Based on the results of this study, coffinitisation of the spent nuclear fuel in deep geological disposal is not anticipated to be a dominant short term process. (author)

  1. Study of Au+Au relativistic collisions with the Fopi-Phase I detector; Etude des collisions relativistes Au+Au avec le detecteur Fopi-Phase I

    Energy Technology Data Exchange (ETDEWEB)

    Dupieux, P

    1995-01-01

    Au+Au relativistic collisions, in a 100-1000 MeV energy domain per nucleon, are described. Experiments have been carried out with the SIS accelerator at GSI/Darmstadt. Data are analysed with the FOPI-phase I detector. These data are compared with IQMD model (Isospin Quantum Molecular Dynamics) Predictions. (S.G). 80 refs., 77 figs., 5 tabs.

  2. Modelling and numerical simulation of liquid-vapor phase transitions; Modelisation et simulation numerique des transitions de phase liquide-vapeur

    Energy Technology Data Exchange (ETDEWEB)

    Caro, F

    2004-11-15

    This work deals with the modelling and numerical simulation of liquid-vapor phase transition phenomena. The study is divided into two part: first we investigate phase transition phenomena with a Van Der Waals equation of state (non monotonic equation of state), then we adopt an alternative approach with two equations of state. In the first part, we study the classical viscous criteria for selecting weak solutions of the system used when the equation of state is non monotonic. Those criteria do not select physical solutions and therefore we focus a more recent criterion: the visco-capillary criterion. We use this criterion to exactly solve the Riemann problem (which imposes solving an algebraic scalar non linear equation). Unfortunately, this step is quite costly in term of CPU which prevent from using this method as a ground for building Godunov solvers. That is why we propose an alternative approach two equations of state. Using the least action principle, we propose a phase changing two-phase flow model which is based on the second thermodynamic principle. We shall then describe two equilibrium submodels issued from the relaxations processes when instantaneous equilibrium is assumed. Despite the weak hyperbolicity of the last sub-model, we propose stable numerical schemes based on a two-step strategy involving a convective step followed by a relaxation step. We show the ability of the system to simulate vapor bubbles nucleation. (author)

  3. Supramolecular organization of organic phases for DIAMEX solvent extraction process; Organisation supramoleculaire des phases organiques de malonamides du procede d'extraction DIAMEX

    Energy Technology Data Exchange (ETDEWEB)

    Martinet, L

    2005-04-15

    In the frame of nuclear waste cycle, supramolecular organization of organic phases has been studied for DIAMEX solvent extraction process. A general methodology has been developed in order to determine surfactant properties of an extractant at high concentration. An illustration is given by a malonamide (DMDBTDMA) at 0.7 mol/L, in dodecane and contacted with water, at 23 deg C. The concentrations of monomers (0.3 mol/L) and aggregates (0.4 mol/L), c.m.c. (0.25 mol/L), aggregation number (4,4), aggregation constant (7.7) and finally aggregates interactions (U/kT = -1.6) are quantified. The method is based on simultaneous utilization of four experimental techniques (small X-ray and neutron scattering, vapour pressure osmometry and tensiometry) added to the model of Baxter. The structure of malonamide organic phase is depending on extractant concentration. (i) Below 0.2 mol/L, it is a quasi-molecular liquid fluid, extracting few amount of solutes. (ii) From 0.2 to 1 mol/L, it is a complex liquid fluid, containing small spherical aggregates of 5 extractant molecules in coexistence with monomers. This phase behaves like typical microemulsions with reverse micelles, through its stabilizing effect of penetrating oil and steric repulsion between extractants. (iii) Above 1 mol/L, the organic phase is able to extract huge amount of solutes. When HNO{sub 3} or Nd(NO{sub 3} ){sub 3} are extracted, a gel with a pseudo-lamellar structure is observed. With UO{sub 2} (NO{sub 3} ){sub 2} a solid crystal with a ratio DMDBTDMA/UO{sub 2} (NO{sub 3} ){sub 2} equal to 1/1 is characteristic of the organic phase. The 'third phase' due to attractive interactions between aggregates has exactly the same supramolecular structure than an 'unsplitted organic phase' of the same composition. Aggregates interactions are independent on the chemical affinity of the extractant for solutes. (author)

  4. Supramolecular organization of organic phases for DIAMEX solvent extraction process; Organisation supramoleculaire des phases organiques de malonamides du procede d'extraction DIAMEX

    Energy Technology Data Exchange (ETDEWEB)

    Martinet, L

    2005-04-15

    In the frame of nuclear waste cycle, supramolecular organization of organic phases has been studied for DIAMEX solvent extraction process. A general methodology has been developed in order to determine surfactant properties of an extractant at high concentration. An illustration is given by a malonamide (DMDBTDMA) at 0.7 mol/L, in dodecane and contacted with water, at 23 deg C. The concentrations of monomers (0.3 mol/L) and aggregates (0.4 mol/L), c.m.c. (0.25 mol/L), aggregation number (4,4), aggregation constant (7.7) and finally aggregates interactions (U/kT = -1.6) are quantified. The method is based on simultaneous utilization of four experimental techniques (small X-ray and neutron scattering, vapour pressure osmometry and tensiometry) added to the model of Baxter. The structure of malonamide organic phase is depending on extractant concentration. (i) Below 0.2 mol/L, it is a quasi-molecular liquid fluid, extracting few amount of solutes. (ii) From 0.2 to 1 mol/L, it is a complex liquid fluid, containing small spherical aggregates of 5 extractant molecules in coexistence with monomers. This phase behaves like typical microemulsions with reverse micelles, through its stabilizing effect of penetrating oil and steric repulsion between extractants. (iii) Above 1 mol/L, the organic phase is able to extract huge amount of solutes. When HNO{sub 3} or Nd(NO{sub 3} ){sub 3} are extracted, a gel with a pseudo-lamellar structure is observed. With UO{sub 2} (NO{sub 3} ){sub 2} a solid crystal with a ratio DMDBTDMA/UO{sub 2} (NO{sub 3} ){sub 2} equal to 1/1 is characteristic of the organic phase. The 'third phase' due to attractive interactions between aggregates has exactly the same supramolecular structure than an 'unsplitted organic phase' of the same composition. Aggregates interactions are independent on the chemical affinity of the extractant for solutes. (author)

  5. Study of cements silicate phases hydrated under high pressure and high temperature; Etude des phases silicatees du ciment hydrate sous haute pression et haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Meducin, F.

    2001-10-01

    This study concerns the durability of oil-well cementing. Indeed, in oil well cementing a cement slurry is pumped down the steel casing of the well up the annular space between it and the surrounding rock to support and protect the casing. The setting conditions of pressure and temperature may be very high (up to 1000 bar and 250 deg C at the bottom of the oil-well). In this research, the hydration of the main constituent of cement, synthetic tri-calcium silicate Ca{sub 3}SiO{sub 2}, often called C{sub 3}S (C = CaO; S = SiO{sub 2} and H H{sub 2}O), is studied. Calcium Silicate hydrates are prepared in high-pressure cells to complete their phase diagram (P,T) and obtain the stability conditions for each species. Indeed, the phases formed in these conditions are unknown and the study consists in the hydration of C{sub 3}S at different temperatures, pressures, and during different times to simulate the oil-well conditions. In a first step (until 120 deg C at ambient pressure) the C-S-H, a not well crystallized and non-stoichiometric phase, is synthesized: it brings adhesion and mechanical properties., Then, when pressure and temperature increase, crystallized phases appear such as jaffeite (Ca{sub 6}(Si{sub 2}O{sub 7})(OH){sub 6}) and hillebrandite (Ca{sub 2}(SiO{sub 3})(OH){sub 2}). Silicon {sup 29}Si Nuclear Magnetic Resonance (using standard sequences MAS, CPMAS) allow us to identify all the silicates hydrates formed. Indeed, {sup 29}Si NMR is a valuable tool to determine the structure of crystallized or not-well crystallized phases of cement. The characterization of the hydrated samples is completed by other techniques: X- Ray Diffraction and Scanning Electron Microscopy. The following results are found: jaffeite is the most stable phase at C/S=3. To simulate the hydration of real cement, hydration of C{sub 3}S with ground quartz and with or without super-plasticizers is done. In those cases, new phases appear: kilchoanite mainly, and xonotlite. A large amount of

  6. Metallurgical study and phase diagram calculations of the Zr-Nb-Fe-(Sn,O) system; Etude metallurgique et calculs des diagrammes de phases des alliages base zirconium du systeme: Zr-Nb-Fe-(O,Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Toffolon, C. [CEA/Saclay, Dept. d' Etudes du Comportement des Materiaux (DECM), 91 - Gif-sur-Yvette (France)]|[Paris-6 Univ., 75 (France)

    2000-07-01

    The Framatome M5{sup TM} Zr-Nb-O alloy with small amounts of Fe is of interest for nuclear applications (PWR fuel cladding).The behaviour of this kind of alloy for in-service conditions strongly depends on the microstructure. Therefore, a metallurgical study of alloys of the Zr-Nb-Fe-(O-Sn) system has been developed in order to study the influence of chemical composition variabilities of Nb, Fe and O and thermal treatments on the resultant microstructure. In order to get some insight on the physical metallurgy of Zr-Nb-Fe-(Sn,O) alloys and to minimize the experiments, it is useful to build a thermodynamic database. With this object, it was necessary to re-optimize and to calculate the low order binary systems such as Fe-Nb and Nb-Sn in order to assess the Zr-Nb-Fe-(Sn,O) system. Then, the experimental studies concerned: the influence of small variations in Nb and O contents on the {alpha}/{beta} transus temperatures. A comparison between experimental results and thermodynamic predictions showed a good agreement; the precipitation kinetics of {beta}Nb and intermetallic phases in the {alpha} phase domain. These experiments showed that the kinetics depends on the initial metallurgical conditions; the determination of the crystallographic structure and the stoichiometry of the ternary Zr-Nb-Fe intermetallic compounds as a function of the temperature. Finally, these experimental data were used to propose a first assessment of the Zr-Nb-Fe(O{approx}1200 ppm) system. (author)

  7. Conception et evaluation d'une intervention didactique a propos des phases de la lune dans un planetarium numerique

    Science.gov (United States)

    Chastenay, Pierre

    Since the Quebec Education Program came into effect in 2001, Quebec classrooms have again been teaching astronomy. Unfortunately, schools are ill-equipped to teach complex astronomical concepts, most of which occur outside school hours and over long periods of time. Furthermore, many astronomical phenomena involve celestial objects travelling through three-dimensional space, which we cannot access from our geocentric point of view. The lunar phases, a concept prescribed in secondary cycle one, fall into that category. Fortunately, schools can count on support from the planetarium, a science museum dedicated to presenting ultra-realistic simulations of astronomical phenomena in fast time and at any hour of the day. But what type of planetarium will support schools? Recently, planetariums also underwent their own revolution: they switched from analogue to digital, replacing geocentric opto-mechanical projectors with video projectors that offer the possibility of travelling virtually through a completely immersive simulation of the three-dimensional Universe. Although research into planetarium education has focused little on this new paradigm, certain of its conclusions, based on the study of analogue planetariums, can help us develop a rewarding teaching intervention in these new digital simulators. But other sources of inspiration will be cited, primarily the teaching of science, which views learning no longer as the transfer of knowledge, but rather as the construction of knowledge by the learners themselves, with and against their initial conceptions. The conception and use of constructivist learning environments, of which the digital planetarium is a fine example, and the use of simulations in astronomy will complete our theoretical framework and lead to the conception of a teaching intervention focusing on the lunar phases in a digital planetarium and targeting students aged 12 to 14. This teaching intervention was initially tested as part of development

  8. The recommendations of the Commission to review the financing of the nuclear power phase-out (KFK); Die Empfehlungen der Kommission zur Ueberpruefung der Finanzierung des Kernenergieausstiegs (KFK)

    Energy Technology Data Exchange (ETDEWEB)

    Ziehm, Cornelia

    2016-07-15

    The federal government has decided to set up a ''Commission to review the financing of the nuclear power phase-out'' (KFK) on October 14, 2015. On April 27, 2016, KFK has submitted its final report. Proposed is the following fact: In the future, the one who have the financial security obligation, which also has the duty to act in the chain of nuclear waste management. Concretely, the tasks of storage and disposal of radioactive waste and the necessary resources be transferred to the state as security. For the remaining tasks, ie in particular the decommissioning and dismantling of nuclear power plants and the packaging of radioactive waste for interim storage, the tasks and financial assurance should remain with the company. For the storage and final disposal a public fund should be established. For a full deposit totaling 23.3 billion euros the risks for the storage and disposal will be transferred to the State. The liability of operators for interim storage and final disposal end with the complete transfer of funds and payment done of the full risk premium. For the decommissioning of nuclear power plants and the packaging of the radioactive waste it will then remain in the system of commercial law reserves. Although in terms of storage and final disposal shall be a departure of the system of the commercial law reserves. However, operators are being released from liabilities - at a time in which over decades and decades arising expenses are only partially quantifiable. [German] Die Bundesregierung hat am 14. Oktober 2015 die Einsetzung einer ''Kommission zur Ueberpruefung der Finanzierung des Kernenergieausstiegs'' (KFK) beschlossen. Am 27. April 2016 hat die KFK ihren Abschlussbericht vorgelegt. Vorgeschlagen wird darin Folgendes: Kuenftig soll derjenige die finanzielle Sicherungspflicht haben, der auch die Pflicht zur Handlung in der Kette der nuklearen Entsorgung hat. Konkret sollen die Aufgaben der Zwischen- und

  9. Self-consistent Random Phase Approximation applied to a schematic model of the field theory; Approximation des phases aleatoires self-consistante appliquee a un modele schematique de la theorie des champs

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, Thierry [Inst. de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France)

    1998-12-11

    The self-consistent Random Phase Approximation (SCRPA) is a method allowing in the mean-field theory inclusion of the correlations in the ground and excited states. It has the advantage of not violating the Pauli principle in contrast to RPA, that is based on the quasi-bosonic approximation; in addition, numerous applications in different domains of physics, show a possible variational character. However, the latter should be formally demonstrated. The first model studied with SCRPA is the anharmonic oscillator in the region where one of its symmetries is spontaneously broken. The ground state energy is reproduced by SCRPA more accurately than RPA, with no violation of the Ritz variational principle, what is not the case for the latter approximation. The success of SCRPA is the the same in case of ground state energy for a model mixing bosons and fermions. At the transition point the SCRPA is correcting RPA drastically, but far from this region the correction becomes negligible, both methods being of similar precision. In the deformed region in the case of RPA a spurious mode occurred due to the microscopical character of the model.. The SCRPA may also reproduce this mode very accurately and actually it coincides with an excitation in the exact spectrum 40 refs., 33 figs., 14 tabs.

  10. Influence of phase transformations on the mechanical behaviour of refractory ceramics at high temperature;Effets des transformations de phase sur la tenue mecanique a haute temperature des ceramiques refractaires

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, N. [LMT-Cachan, ENS de Cachan, UMR 8535 CNRS, Universite Paris 6, 94 - Cachan (France); IUFM de Creteil, Universite Paris-Est Creteil, 93 - Saint-Denis (France); Poirier, J. [CNRS-CEMHTI, 45 - Orleans (France); Polytech, Universite d' Orleans, 45 - Orleans (France)

    2009-07-01

    Refractories used at high temperature are subjected to high chemical and mechanical stresses. The mastery of their microstructure as well as the phase changes occurring in service is essential to ensure resistance to wear and failure of refractory linings. Great progress has been made: combining efficient techniques for the investigation of the microstructure with powerful numerical tools (thermochemical and thermo-mechanical computations) provides information (e.g., degradation mechanisms) that cannot be obtained directly. Also multi-physical and multi-scale models developing materials with high-performance for higher temperature and with longer lifetime. In this paper, through several examples we show some interactions between the mechanical behavior and the microstructure transformations of refractory ceramics. The tools developed to characterize their microstructure change in situ (e.g., at high temperature) and to identify their kinetics are described. Some methodologies and tools developed in recent years, today, provide a better understanding of in-service behavior of refractories while identifying the critical material and process parameters likely to increase life-time. (authors)

  11. X-ray-phase and IR-spectral study of clay rocks mineral content of the Caspian Sea Gulf depression

    International Nuclear Information System (INIS)

    Zakonov, A.N.; Mukhanova, M.U.

    2000-01-01

    Samples of clays selected from different oil fields (Sazankurak, Kemerkol, Kozha and others) and deposition depths are examined on both the X-ray diffractometers (Dron-2 and Dron-4) and the infrared-spectrometers (IR-20). In this diagnostic the American file with different minerals X-ray systematized data is used. The X-ray reflections, which are in compliance with suitable inter-plane distances and clay impurities reflex intensities are determined. With confirmation purpose for mineral content correctness obtained according X-ray-phase analysis the infrared-spectrometric method is used, in which principal attention was paid to absorption field (3,400-3,700 cm -1 ) of H 2 O and OH valency frequency vibrations

  12. Fundamental equations for two-phase flow. Part 1: general conservation equations. Part 2: complement and remarks; Equations fondamentales des ecoulements diphasiques. Premiere partie: equations generales de conservation. Deuxieme partie: complements et remarques

    Energy Technology Data Exchange (ETDEWEB)

    Delhaye, J M [Commissariat a l' Energie Atomique, 38 - Grenoble (France). Centre d' Etudes Nucleaires

    1968-12-01

    equations concerning different methods of presenting two-phase flows with those proposed in the literature. As a result a detailed study has been made of the work of C.G. TELETOV, S.S. KUTATELADZE, M.A. STYRIKOVICH and N. ZUBER; a summary of this work presented. (author) [French] Ce rapport traite des equations generales de conservation de la masse, de la quantite de mouvement et de l'energie pour un ecoulement diphasique. Ces equations sont presentees sous plusieurs formes a partir des equations integrales qui sont posees a priori. 1. Equations aux variables locales instantanees et conditions d'interface; 2. Equations aux variables instantanees moyennees dans une section et applications pratiques: ces equations renferment une donnee experimentale interessante qui est le rapport de la section de passage d'une phase sur la section totale d'une conduite. 3. Equations aux moyennes statistiques locales et equations moyennees dans le temps: une tentative plus poussee pour relier experience et theorie consiste a prendre les moyennes statistiques des equations locales. On obtient alors des equations ou interviennent des variables moyennees dans le temps par application d'une hypothese ergodique. 4. Combinaisons des moyennes statistiques et des moyennes dans une section: on considere dans cette etude des variables locales moyennees statistiquement, puis moyennees dans la section et egalement des variables moyennees dans la section puis moyennees statistiquement. 5. Equations generales relatives aux emulsions: dans ce cas, une phase se presente (localement sous un aspect tres divise. Cette particularite permet de definir une concentration volumique locale et d'etablir des equations aux applications multiples. On a complete et precise certains points de la premiere partie de ce rapport concernant les equations generales de conservation des ecoulements diphasiques. On a introduit dans les equations generales les termes correspondant a la tension interfaciale. Les conditions d

  13. Fundamental equations for two-phase flow. Part 1: general conservation equations. Part 2: complement and remarks; Equations fondamentales des ecoulements diphasiques. Premiere partie: equations generales de conservation. Deuxieme partie: complements et remarques

    Energy Technology Data Exchange (ETDEWEB)

    Delhaye, J.M. [Commissariat a l' Energie Atomique, 38 - Grenoble (France). Centre d' Etudes Nucleaires

    1968-12-01

    equations concerning different methods of presenting two-phase flows with those proposed in the literature. As a result a detailed study has been made of the work of C.G. TELETOV, S.S. KUTATELADZE, M.A. STYRIKOVICH and N. ZUBER; a summary of this work presented. (author) [French] Ce rapport traite des equations generales de conservation de la masse, de la quantite de mouvement et de l'energie pour un ecoulement diphasique. Ces equations sont presentees sous plusieurs formes a partir des equations integrales qui sont posees a priori. 1. Equations aux variables locales instantanees et conditions d'interface; 2. Equations aux variables instantanees moyennees dans une section et applications pratiques: ces equations renferment une donnee experimentale interessante qui est le rapport de la section de passage d'une phase sur la section totale d'une conduite. 3. Equations aux moyennes statistiques locales et equations moyennees dans le temps: une tentative plus poussee pour relier experience et theorie consiste a prendre les moyennes statistiques des equations locales. On obtient alors des equations ou interviennent des variables moyennees dans le temps par application d'une hypothese ergodique. 4. Combinaisons des moyennes statistiques et des moyennes dans une section: on considere dans cette etude des variables locales moyennees statistiquement, puis moyennees dans la section et egalement des variables moyennees dans la section puis moyennees statistiquement. 5. Equations generales relatives aux emulsions: dans ce cas, une phase se presente (localement sous un aspect tres divise. Cette particularite permet de definir une concentration volumique locale et d'etablir des equations aux applications multiples. On a complete et precise certains points de la premiere partie de ce rapport concernant les equations generales de conservation des ecoulements diphasiques. On a introduit dans les equations generales les termes correspondant a la tension

  14. Diffractive centrosymmetric 3D-transmission phase gratings positioned at the image plane of optical systems transform lightlike 4D-WORLD as tunable resonators into spectral metrics...

    Science.gov (United States)

    Lauinger, Norbert

    1999-08-01

    Diffractive 3D phase gratings of spherical scatterers dense in hexagonal packing geometry represent adaptively tunable 4D-spatiotemporal filters with trichromatic resonance in visible spectrum. They are described in the (lambda) - chromatic and the reciprocal (nu) -aspects by reciprocal geometric translations of the lightlike Pythagoras theorem, and by the direction cosine for double cones. The most elementary resonance condition in the lightlike Pythagoras theorem is given by the transformation of the grating constants gx, gy, gz of the hexagonal 3D grating to (lambda) h1h2h3 equals (lambda) 111 with cos (alpha) equals 0.5. Through normalization of the chromaticity in the von Laue-interferences to (lambda) 111, the (nu) (lambda) equals (lambda) h1h2h3/(lambda) 111-factor of phase velocity becomes the crucial resonance factor, the 'regulating device' of the spatiotemporal interaction between 3D grating and light, space and time. In the reciprocal space equal/unequal weights and times in spectral metrics result at positions of interference maxima defined by hyperbolas and circles. A database becomes built up by optical interference for trichromatic image preprocessing, motion detection in vector space, multiple range data analysis, patchwide multiple correlations in the spatial frequency spectrum, etc.

  15. Spectral emissivities at wavelengths in the range 500--653 nm, enthalpies, and heat capacities of the liquid phases of cobalt, titanium, and zirconium

    International Nuclear Information System (INIS)

    Qin, J.; Roesner-Kuhn, M.; Drewes, K.; Thiedemann, U.; Kuppermann, G.; Camin, B.; Blume, R.; Frohberg, M.G.

    1997-01-01

    A review is given of the literature data for spectral emissivities at wavelengths (λ) in the range 500--653 nm, the enthalpies, and heat capacities of the liquid phases of cobalt, titanium, and zirconium. Emissivity measurements were carried out by means of electromagnetic levitation at the solid-to-liquid transition with a partial-radiation pyrometer operating at λ = 547 and 650 nm. Considering the sensitivity of the optical properties to surface impurities, investigations on the surfaces of several titanium and zirconium samples by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were performed that confirmed a nitrogen- and oxygen-free process atmosphere during the measurements. Liquid phase normal emissivities obtained were var-epsilon n,547 = 0.365 and var-epsilon n,650 = 0.331 for cobalt, var-epsilon n,547 = 0.409 and var-epsilon n,650 = 0.393 for titanium, and var-epsilon n,547 = 0.365 and var-epsilon n,650 = 0.355 for zirconium. Enthalpy measurements on the liquid metals were carried out by means of levitation-drop calorimetry in the range 1591--2159 K for cobalt, 1847--2430 K for titanium, and 2025--2897 K for zirconium. The resulting heat capacities (values in J·mol -1 ·K -1 ) obtained were 42.78 for cobalt, 43.79 for titanium, and 39.81 for zirconium

  16. Application of the finite-element method and the eigenmode expansion method to investigate the periodic and spectral characteristic of discrete phase-shift fiber Bragg grating

    Science.gov (United States)

    He, Yue-Jing; Hung, Wei-Chih; Syu, Cheng-Jyun

    2017-12-01

    The finite-element method (FEM) and eigenmode expansion method (EEM) were adopted to analyze the guided modes and spectrum of phase-shift fiber Bragg grating at five phase-shift degrees (including zero, 1/4π, 1/2π, 3/4π, and π). In previous studies on optical fiber grating, conventional coupled-mode theory was crucial. This theory contains abstruse knowledge about physics and complex computational processes, and thus is challenging for users. Therefore, a numerical simulation method was coupled with a simple and rigorous design procedure to help beginners and users to overcome difficulty in entering the field; in addition, graphical simulation results were presented. To reduce the difference between the simulated context and the actual context, a perfectly matched layer and perfectly reflecting boundary were added to the FEM and the EEM. When the FEM was used for grid cutting, the object meshing method and the boundary meshing method proposed in this study were used to effectively enhance computational accuracy and substantially reduce the time required for simulation. In summary, users can use the simulation results in this study to easily and rapidly design an optical fiber communication system and optical sensors with spectral characteristics.

  17. Quantum field theory and phase transitions: universality and renormalization group; Theorie quantique des champs et transitions de phase: universalite et groupe de renormalisation

    Energy Technology Data Exchange (ETDEWEB)

    Zinn-Justin, J

    2003-08-01

    In the quantum field theory the problem of infinite values has been solved empirically through a method called renormalization, this method is satisfying only in the framework of renormalization group. It is in the domain of statistical physics and continuous phase transitions that these issues are the easiest to discuss. Within the framework of a course in theoretical physics the author introduces the notions of continuous limits and universality in stochastic systems operating with a high number of freedom degrees. It is shown that quasi-Gaussian and mean field approximation are unable to describe phase transitions in a satisfying manner. A new concept is required: it is the notion of renormalization group whose fixed points allow us to understand universality beyond mean field. The renormalization group implies the idea that long distance correlations near the transition temperature might be described by a statistical field theory that is a quantum field in imaginary time. Various forms of renormalization group equations are presented and solved in particular boundary limits, namely for fields with high numbers of components near the dimensions 4 and 2. The particular case of exact renormalization group is also introduced. (A.C.)

  18. 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

    1998-12-31

    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.

  19. 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.

  20. A Model of Secondary Hydrocarbon Migration As a Buoyancy-Driven Separate Phase Flow Un modèle de migration secondaire des hydrocarbures considéré comme un écoulement en phases séparées régi par la poussée d'Archimède

    Directory of Open Access Journals (Sweden)

    Lehner F. K.

    2006-11-01

    Full Text Available A mathematical model of secondary migration is described which permits the prediction of hydrocarbon migration and accumulation patterns in a sedimentary basin, if source rock expulsion rates and geometrical and hydraulic properties of major carrier systems are known through geological time. In this model, secondary migration is treated as buoyancy-driven, segregated flow of hydrocarbons in hydrostatic aquifers. Lateral, updip migration is conceived as a Boussinesq-type, free-surface flow, with source and sink terms representing supply from source rocks and leakage through cap rocks and faults. This permits a two-dimensional, map-view mathematical description of a three-dimensional, time-dependent secondary migration system. A nine-point finite difference approximation has been developed to minimize numerical dispersion, and upstream-weighting is used to obtain stable solutions. Example computations for simple, single carrier bed structures are presented. L'article décrit un modèle mathématique de migration secondaire prédisant la migration des hydrocarbures et leur accumulation dans un bassin sédimentaire, lorsque les taux d'expulsion des roches mères et les propriétés géométriques et hydrauliques des principaux systèmes de drainage sont connus à l'échelle du temps géologique. Dans ce modèle, la migration secondaire est traitée comme un écoulement des hydrocarbures en phase séparée, contrôlé par la poussée d'Archimède, dans des aquifères hydrostatiques. La migration latérale est considérée comme un écoulement de type Boussinesq, à surface libre, avec des termes sources et puits représentant les apports venant des roches mères et les fuites à travers les couvertures et les failles. Ceci permet une description mathématique bidimensionnelle cartographiable d'un système de migration secondaire tridimensionnel et dépendant du temps. On utilise une approximation type différences finies à neuf points pour minimiser

  1. Tunable optical switching in the near-infrared spectral regime by employing plasmonic nanoantennas containing phase change materials.

    Science.gov (United States)

    Savaliya, Priten B; Thomas, Arun; Dua, Rishi; Dhawan, Anuj

    2017-10-02

    We propose the design of switchable plasmonic nanoantennas (SPNs) that can be employed for optical switching in the near-infrared regime. The proposed SPNs consist of nanoantenna structures made up of a plasmonic metal (gold) such that these nanoantennas are filled with a switchable material (vanadium dioxide). We compare the results of these SPNs with inverted SPN structures that consist of gold nanoantenna structures surrounded by a layer of vanadium dioxide (VO 2 ) on their outer surface. These nanoantennas demonstrate switching of electric-field intensity enhancement (EFIE) between two states (On and Off states), which can be induced thermally, optically or electrically. The On and Off states of the nanoantennas correspond to the metallic and semiconductor states, respectively of the VO 2 film inside or around the nanoantennas, as the VO 2 film exhibits phase transition from its semiconductor state to the metallic state upon application of thermal, optical, or electrical energy. We employ finite-difference time-domain (FDTD) simulations to demonstrate switching in the EFIE for four different SPN geometries - nanorod-dipole, bowtie, planar trapezoidal toothed log-periodic, and rod-disk - and compare their near-field distributions for the On and Off states of the SPNs. We also demonstrate that the resonance wavelength of the EFIE spectra gets substantially modified when these SPNs switch between the two states.

  2. La cartog ra ph ie des inc iden ce s

    International Development Research Centre (IDRC) Digital Library (Canada)

    IDRC CRDI

    che d'ingénierie des incidences à la recherche pour le développe- ment. .... çoivent des stratégies visant à les doter des outils, techniques et ressources utiles pour contribuer au développement. Axer le ... Comment ? La première phase, la définition des intentions, aide le programme à en arriver à un consensus sur les.

  3. Application of wavelet analysis to the nuclear phase space study; Application de l`analyse en ondelettes a l`etude de l`espace des phases nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Jouault, B. [Nantes Univ., 44 (France)

    1996-11-22

    The objective of this thesis is to present a methodology, based on the projection methods used in statistical physics and on the wavelet approach, which allows to obtain various classes of information. A coherent modelling was elaborated as the tools used for generating and solving the evolution equations, expressed in terms of pertinent variables, are based on common concepts. The property of scale separation of the wavelet analysis allows an approximation hierarchy based on the geometrical structure of phase space to be defined. This information structuration offers the opportunity of solving the evolution equations with various degrees of precision by controlling the information loss and avoiding the sampling methods of Monte Carlo type. The application of this methodology to the case of heavy ion collisions needs an entirely numerical treatment of the density matrix evolution equation. This implies a very precise level of description in order to take into account the important dissipation effects occurring in intermediate energy nuclear dynamics. A proper solution less expensive was adopted by using the wavelets analytically expressed, this entailing also the testing of model validity by comparing its results with the analytical solutions. This model takes into account the structure of the system wave functions, thus conserving the microscopical information. The present methodology can be applied also at other energy domains providing the nuclear systems are subject to transient non steady-state regimes. The wavelet analysis was used extensively in the field of signal processing particularly to extract from background a physical signal and also in the field of turbulence phenomena 152 refs.

  4. Molecular Simulations As a Tool for Predicting Phase Equilibria and Transport Properties of Fluids Les simulations moléculaires comme outils pour prédire les équilibres de phases et les propriétés de transport des fluides

    Directory of Open Access Journals (Sweden)

    Fuchs A.

    2006-12-01

    Full Text Available koWe briefly review the molecular simulation methods which can be used to predict thermophysical properties of fluids and fluid mixtures. It is shown in this paper, on the one hand, how the Gibbs Ensemble Monte Carlo Method allows phase behavior predictions for real fluids under conditions for which experimental data are difficult or impossible to obtain. On the other hand, the molecular dynamics methods used for predicting transport properties of molecular fluids are described. Finally we discuss possible future applications of these methods. Dans cet article, nous passons brièvement en revue les méthodes de simulation moléculaire applicables à la prédiction des propriétés thermophysiques des fluides et des mélanges. Nous montrons, d'une part, comment la méthode de Monte-Carlo dans l'ensemble de Gibbs permet de prédire le comportement de phase de fluides réels dans des conditions telles que l'acquisition de données expérimentales serait difficile, voire impossible. D'autre part, nous décrivons les méthodes de dynamique moléculaire utilisées pour prédire les propriétés de transport de fluides moléculaires. Enfin, nous discutons le potentiel de ces méthodes pour les applications futures.

  5. Versatile high-repetition-rate phase-locked chopper system for fast timing experiments in the vacuum ultraviolet and x-ray spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Plogmaker, Stefan; Johansson, Erik M. J.; Rensmo, Haakan; Feifel, Raimund; Siegbahn, Hans [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Linusson, Per [Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden); Eland, John H. D. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom); Baker, Neville [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom)

    2012-01-15

    A novel light chopper system for fast timing experiments in the vacuum-ultraviolet (VUV) and x-ray spectral region has been developed. It can be phase-locked and synchronized with a synchrotron radiation storage ring, accommodating repetition rates in the range of {approx}8 to {approx}120 kHz by choosing different sets of apertures and subharmonics of the ring frequency (MHz range). Also the opening time of the system can be varied from some nanoseconds to several microseconds to meet the needs of a broad range of applications. Adjusting these parameters, the device can be used either for the generation of single light pulses or pulse packages from a microwave driven, continuous He gas discharge lamp or from storage rings which are otherwise often considered as quasi-continuous light sources. This chopper can be utilized for many different kinds of experiments enabling, for example, unambiguous time-of-flight (TOF) multi-electron coincidence studies of atoms and molecules excited by a single light pulse as well as time-resolved visible laser pump x-ray probe electron spectroscopy of condensed matter in the valence and core level region.

  6. Spectral stratigraphy

    Science.gov (United States)

    Lang, Harold R.

    1991-01-01

    A new approach to stratigraphic analysis is described which uses photogeologic and spectral interpretation of multispectral remote sensing data combined with topographic information to determine the attitude, thickness, and lithology of strata exposed at the surface. The new stratigraphic procedure is illustrated by examples in the literature. The published results demonstrate the potential of spectral stratigraphy for mapping strata, determining dip and strike, measuring and correlating stratigraphic sequences, defining lithofacies, mapping biofacies, and interpreting geological structures.

  7. Détermination automatique de l'indice d'octane et de la composition des reformats par chromatographie en phase gazeuse Automatic Determination of Reformate Octane Number and Composition by Gas Chromatography

    Directory of Open Access Journals (Sweden)

    Petroff N.

    2006-11-01

    Full Text Available Utilisant des analyses par chromatographie en phase gazeuse, diverses méthodes ont été testées pour calculer l'indice d'octane de reformats. L'une d'elles s'est imposée par la simplicité de l'appareillage, ses possibilités d'automatisation et son adéquation à des échantillons provenant de charges différentes. Cette étude décrit les conditions opératoires de la méthode chromatographique optimisées pour les réformes, en vue d'obtenir des valeurs calculées de l'indice d'octane (IO dit Recherche différant de moins de un point des valeurs mesurées sur un moteur CFR selon la norme ASTM/D2699 (NF MO7026. L'analyse chromatographique est faite sur une colonne capillaire fonctionnant en température programmée. Le traitement des données est réalisé par un logiciel qui assure àla fois l'identification des constituants et le calcul de l'indice d'octane, à partir des données chromatographiques standard (temps de rétention et surface des pics. Les résultats obtenus portent sur une soixantaine de reformats divers. La fiabilité de la méthode d'identification, la répétabilité et la reproductibilité des valeurs de IO calculés sont démontrées. Ces résultats permettent d'envisager l'exploitation de la méthode en sortie d'unité. Various methods were tested by gas chromatography analysis for calculating the octane number of reformates. One of them was superior because of the simplicity of its equipment, its possibilities of automation and its suitability for samples coming from different feeds. This article describes the operating conditions of the optimized chromatographic method for reformates with a view to obtaining calculated values of the so-called Researchoctane number (RON different by at least one point from the values measured with a CFR engine according to the ASTM/D2699 standard. Chromatographic analysis is performed in a capillary column operating with programmedtemperature. Data processing is done with a software

  8. Projecting phase terminated, implementation coming soon. Environment-friendly heat supply at Ruhpolding sports center; Projekt ausgereift - Betreiber gesucht.. Oekologische Waermeversorgung des Ruhpoldinger Sport- und Freizeitzentrums

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2000-02-01

    When the public indoor swimming pool at Ruhpolding was modernized, the community took the chance to convert the whole sports and recreation center (indoor and outdoor swimming pools, skating rink and multi-purpose hall) as well as the school buildings to district heat supply from a biomass-fuelled heating power station. Apart from the financial savings, this solution also reduces exhaust emissions and makes this recreation area mor attractive. [German] Mit der Sanierung und Erweiterung des Wellenhallenbades bietet sich der Gemeinde Ruhpolding die Gelegenheit, die Waermeversorgung des Sport- und Freizeitzentrums (Wellenhallenbad, Freibad, Eissporthalle und Mehrzweckhalle) und der Schulgebaeude von der Einzelversorgung mit Oelkesseln auf die Nahwaermeversorgung mittels Biomasse-Heizwerk umzustellen. Das bringt der Gemeinde nicht nur finanzielle Vorteile, sondern entlastet das Kurgebiet erheblich von schaedlichen Abgasen und erhoeht damit die Attraktivitaet des Erholungsortes. (orig.)

  9. Des proprietes de l'etat normal du modele de Hubbard bidimensionnel

    Science.gov (United States)

    Lemay, Francois

    Depuis leur decouverte, les etudes experimentales ont demontre que les supra-conducteurs a haute temperature ont une phase normale tres etrange. Les proprietes de ces materiaux ne sont pas bien decrites par la theorie du liquide de Fermi. Le modele de Hubbard bidimensionnel, bien qu'il ne soit pas encore resolu, est toujours considere comme un candidat pour expliquer la physique de ces composes. Dans cet ouvrage, nous mettons en evidence plusieurs proprietes electroniques du modele qui sont incompatibles avec l'existence de quasi-particules. Nous montrons notamment que la susceptibilite des electrons libres sur reseau contient des singularites logarithmiques qui influencent de facon determinante les proprietes de la self-energie a basse frequence. Ces singularites sont responsables de la destruction des quasi-particules. En l'absence de fluctuations antiferromagnetiques, elles sont aussi responsables de l'existence d'un petit pseudogap dans le poids spectral au niveau de Fermi. Les proprietes du modele sont egalement etudiees pour une surface de Fermi similaire a celle des supraconducteurs a haute temperature. Un parallele est etabli entre certaines caracteristiques du modele et celles de ces materiaux.

  10. Parametric Explosion Spectral Model

    Energy Technology Data Exchange (ETDEWEB)

    Ford, S R; Walter, W R

    2012-01-19

    Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. Explosion spectra can be fit with similar spectral models whose parameters are then correlated with near-source geology and containment conditions. We observe a correlation of high gas-porosity (low-strength) with increased spectral slope. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.

  11. ANALYSE DES PERCEPTIONS LOCALES ET DES FACTEURS ...

    African Journals Online (AJOL)

    AISA

    1Faculté des Sciences Agronomiques (FSA), Université d'Abomey-Calavi (UAC), 01 BP 526 Cotonou Bénin. Email : cgbemavo@yahoo.fr. 2Institut National des Recherches Agricoles du Bénin, Centre de Recherches Agricoles d'Agonkanmey (CRA-A),. Laboratoire des Sciences du Sol, Eau et Environnement (LSSEE).

  12. EFFET DES TRAITEMENTS THERMIQUES SUR LA REACTION ENTRE DES COUCHES MINCES DE TITANE ET DES SUBSTRATS EN ACIER

    Directory of Open Access Journals (Sweden)

    D Slimani

    2015-06-01

    Full Text Available Des couches minces du titane pur ont été déposées avec la méthode de pulvérisation cathodique sur des substrats en acier, type FF80 K-1 contenants ~1% mass. en carbone. La réaction entre les deux parties du système substrat-couche mince est activée avec des traitements thermiques sous vide dans l’intervalle de températures de 400 à900°Cpendant 30 minutes. Les Spectres de diffraction de rayons x confirment l’inter- diffusion des éléments  chimiques du système résultants la formation et la croissance des nouvelles phases en particulier le carbure binaire TiC ayant des caractéristiques thermomécaniques importantes. L’analyse morphologique des échantillons traités  avec le microscope électronique à balayage (MEB montre l’augmentation du flux de diffusion atomique avec la température de recuit, notamment la diffusion du manganèse et du fer vers la surface libre des échantillons aux températures élevées provoquant la dégradation des propriétés mécaniques des revêtements contrairement au premiers stades d’interaction où on a obtenu des bonnes valeurs de la microdureté.

  13. Noncommutativity from spectral flow

    Energy Technology Data Exchange (ETDEWEB)

    Heinzl, Thomas; Ilderton, Anton [School of Mathematics and Statistics, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)

    2007-07-27

    We investigate the transition from second- to first-order systems. Quantum mechanically, this transforms configuration space into phase space and hence introduces noncommutativity in the former. This transition may be described in terms of spectral flow. Gaps in the energy or mass spectrum may become large which effectively truncates the available state space. Using both operator and path integral languages we explicitly discuss examples in quantum mechanics (light-front) quantum field theory and string theory.

  14. Analyze of phase's mechanical behaviour of a multiphase polycrystalline alloy by X-ray and neutron diffraction; Analyse du comportement mecanique des constituants d'un alliage polycristallin multiphase par diffraction des rayons X et neutronique

    Energy Technology Data Exchange (ETDEWEB)

    Dakhlaoui, R

    2006-12-15

    The aim of this work is to propose a methodology using diffraction methods and theoretical approaches of self-consistent modeling in order to analyze and better understand the mechanical behavior of each phase of hot-rolled duplex stainless steel. The purpose of the experimental study is to characterize the local mechanical behavior of phases under uniaxial loading. X-ray and neutron diffraction which enable to measure strains in each phase separately were used in this aim. Austenitic and ferritic phase stresses are determined by X-ray diffraction during tensile tests. Evolution of the elastic strains in each phase was measured by neutron diffraction using 'time-of-flight' method during tensile and compression tests. Elastic constants were given using the self-consistent model for a purely elastic deformation. To reproduce the mechanical behaviour of the studied material, self-consistent polycrystalline micro-mechanical model for elastoplastic deformation has been adapted and confronted to experimental results. Crystallographic texture and initial residual stresses were considered in this analysis. Critical shear stresses and hardening parameters of each phase of the studied duplex steel have been identified. Results of this study showed that the austenitic phase represents the softest and the most hardenable phase. Taking into account in calculations the initial residual stresses in the non deformed sample leads to the conclusion that the initial stresses modify considerably the values of phase's yield stresses. Good agreement has been noted comparing results obtained by XRD to those obtained by neutron diffraction. The problem of relaxation of normal stresses in the analysed layer by X-rays was analysed and discussed. Using XRD and self-consistent modelling, the effect of the chemical composition of the duplex stainless steel and the influence of ageing at 400 C degrees for 1000 h on the mechanical behaviour of austenitic and ferritic phases have

  15. RÉALISATION D'UN FILTRE SPECTRAL ACCORDABLE ÉTROIT À 1.55 μm EN OPTIQUE INTÉGRÉE SUR NIOBATE DE LITHIUM. ÉTUDE DES LIMITATIONS IMPOSÉES PAR LA TECHNOLOGIE.

    OpenAIRE

    Chollet , Franck

    1995-01-01

    The exponential growth of the data rate in future telecommunication networks, requires the use of new transmission ways. Optical based networks show great promise for replacing 'slow' electronics technology. Through the use of wavelength division multiplexing technique (WDM), it becomes possible not only to increase the data rate on the line (here, an optical fibre) but also to use new alloptical based network. One of the key devices in these architectures is the tunable spectral filter. The ...

  16. Modelisation des effets physico-techniques pour la conception des ...

    African Journals Online (AJOL)

    automatisation dans les installations industrielles a besoin d'une régulation automatique des commandes des processus technologiques pour lesquelles certaines contraintes sont à relever compte tenu des exigences des innovations scientifiques de ...

  17. Determination of species activities in organic phase. Modelling of liquid-liquid extraction system using uniquac and unifac models; Determination des activites des especes en phase organique. Application d`uniquac et unifac a la modelisation des systemes d`extraction liquide-liquide

    Energy Technology Data Exchange (ETDEWEB)

    Rat, B. [CEA Saclay, 91 - Gif-sur-Yvette (France). Dept. de Recherche en Retraitement et en Vitrification]|[Paris-6 Univ., 75 (France)

    1998-12-31

    The aim of nuclear fuel reprocessing is to separate reusable elements, uranium and plutonium from the other elements, fission products and minor actinides. PUREX process uses liquid-liquid extraction as separation method. Numerical codes for modelling the extraction operations of PUREX process use a semi-empirical model to represent the partition of species. To improve the precision and precision and predictive nature of the models, we looked for a theoretical tool which permits to quantify medium effects, especially in the organic phase, for which few models are available. The Sergeivskii-Dannus model permits to quantify deviations from ideality in organic phase equilibrated with aqueous phase, but with parameters depending on extractant/diluent ratio. We decided to investigate UNIQUAC and UNIFAC models which permit to estimate activity coefficients in non-electrolytic phases taking account of the mutual interactions of molecules and their morphology. UNIFAC is based on UNIQUAC but molecules are considered as structural groups assemblies. Before applying these model to extraction systems, we investigate their abilities to describe simple systems, binary and ternary systems. UNIQUAC has been applied to TBP/diluent mixtures and permits to estimate activity coefficients for diluents whose interactions with TPB are very different in nature and strength. Group contribution (UNIFAC) applied to TBP/alkane mixtures permits to represent the effect of lengthening alkane chain but not the effect of branching. UNIQUAC fails to describe the TBP/diluent/water/non-extractable-salt systems in case of strong TBP diluent interactions. In order to obtain a correct description of these systems, we used the Chem-UNIFAC model, where the INIFAC equation is supplemented with chemical equilibria allowing explicitly for complexes formation and where group contribution is used to describes complexes. We have with Chem-UNIFAC a model available which can take the effect of the diluent into

  18. variabilite des productions et des revenus des exploitations

    African Journals Online (AJOL)

    3Centre de coopération internationale en recherche agronomique pour le développement (CIRAD), UMR Innovation,. Montpellier, France. Doubangolo COULIBALY, Email kone_b@yahoo.fr. RESUME. La durabilité des systèmes de production à base de coton dans un contexte de variabilité des prix aux producteurs et de ...

  19. Caractérisation de composites supraconducteurs aléatoires - phases au bismuth/argent : contribution à l'étude des jonctions faibles dans ces matériaux

    OpenAIRE

    Antunes , Laurent

    1998-01-01

    Les oxydes supraconducteurs à température critique élevée, à base de bismuth et comportant 2 ou 3 plans cuivre, sont synthétisés suivant diverses méthodes. Nous réalisons ensuite l'élaboration par frittage de matériaux composites aléatoires, constitués d'une dispersion de grains supraconducteurs de phase au bismuth 2212 dans une matrice d'argent. Nous étudions la résistivité électrique et l' aimantation en effet d'écran des matériaux en fonction de la température, du champ magnétique et de la...

  20. Two Phase Flow in Nodular Systems: Laboratory Experiments Écoulements polyphasiques dans des systèmes nodulaires : expériences de laboratoire

    Directory of Open Access Journals (Sweden)

    Alhanai W.

    2006-11-01

    Full Text Available Heterogeneity effects within the grid block of a reservoir numerical model are generally taken into account by using pseudo-relative permeability and capillary pressure curves. Some insight into the physics of these pseudo-functions can be obtained from multiple scale analysis such as largescale averaging. Previous theoretical results have shown specific behaviour associated with nodular systems. Laboratory scale experiments were performed that emphasize the difference in behaviour of nodular systems when the properties of the different regions are interchanged. Sandstone nodules embedded in a more permeable continuous region made of sand showed a quasi-static behaviour under experimental conditions while the reverse situation, i. e. sand nodules in a sandstone continuous region, exhibited a totally different behaviour in terms of final saturation and recovery curves. These results are discussed with respect to the large-scale averaging objective. Notre étude s'inscrit dans le cadre général de la prise en compte des hétérogénéités dans la modélisation des écoulements polyphasiques en milieu poreux. Les modèles de gisement utilisent le plus souvent les méthodes de pseudo-fonctions , faisant l'hypothèse que les équations décrivant les écoulements polyphasiques ne sont pas modifiées, dans leur forme, par le changement d'échelle. En fait, il est reconnu que le processus de changement d'échelle peut conduire à des propriétés transitoires, directionnelles et dynamiques. Il est donc nécessaire de bien connaître la physique des écoulements à l'échelle locale pour décrire l'écoulement à une échelle plus grande incluant les hétérogénéités. Le problème physique auquel nous nous intéressons est représenté figure 1. Lors de travaux précédents, Quintard et Whitaker (1988 ont obtenu les résultats suivants : - Dans le cas quasi-statique (écoulement contrôlé par les forces capillaires, les équations à grande

  1. Impact de la preparation des anodes crues et des conditions de cuisson sur la fissuration dans des anodes denses

    Science.gov (United States)

    Amrani, Salah

    electrique a ete suivie et l'etape de devolatilisation a ete identifiee. Certaines anodes ont ete cuites a differents taux de chauffage (bas, moyen, eleve et un autre combine) dans l'objectif de trouver les meilleures conditions de cuisson en vue de minimiser la fissuration. D'autres anodes ont ete cuites a differents niveaux de cuisson, cela dans le but d'identifier a quelle etape de l'operation de cuisson la fissuration commence a se developper. Apres la cuisson, les anodes ont ete recuperees pour, a nouveau, faire leur caracterisation par les memes techniques utilisees precedemment. L'objectif principal de cette partie etait de reveler l'impact de differents parametres sur le probleme de fissuration, qui sont repartis sur toute la chaine de production des anodes. Le pourcentage de megots, la quantite de brai et la distribution des particules sont des facteurs importants a considerer pour etudier l'effet de la matiere premiere sur le probleme de la fissuration. Concernant l'effet des parametres du procede de fabrication sur le meme probleme, le temps de vibration, la pression de compaction et le procede de refroidissement ont ete a la base de cette etude. Finalement, l'influence de la phase de cuisson sur l'apparition de la fissuration a ete prise en consideration par l'intermediaire du taux de chauffage et du niveau de cuisson. Les travaux realises au niveau industriel ont ete faits lors d'une campagne de mesure dans le but d'evaluer la qualite des anodes de carbone en general et l'investigation du probleme de fissuration en particulier. Ensuite, il s'agissait de reveler les effets de differents parametres sur le probleme de la fissuration. Vingt-quatre anodes cuites ont ete utilisees. Elles ont ete fabriquees avec differentes matieres premieres (brai, coke, megots) et sous diverses conditions (pression, temps de vibration). Le parametre de la densite de fissuration a ete calcule en se basant sur l'inspection visuelle de la fissuration des carottes. Cela permet de

  2. Examples of the use of preparative gas-phase chromatography for producing marked molecules; Exemples d'emploi de la chromatographie gazeuse preparative dans la fabrication des molecules marquees

    Energy Technology Data Exchange (ETDEWEB)

    Pichat, L; Baret, Ch; Guermont, J P; Audinot, M [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    the ethyl or methyl acrylate from the nickel carbonyl. The p-cymene-7-C{sup 14} obtained by reducing the cuminic acid labelled with C-14 in the carbonyl group with a mixture of LiAIH{sub 4} and AlCl{sub 3} is contaminated by cuminic alcohol-7-C{sup 14} which cannot be separated by distillation in microquantities. Gas chromatography on a silicone column at 125 deg. C made it, possible to obtain pure p-cymene. (author) [French] La chromatographie gazeuse est le plus couramment utilisee dans l'analyse des produits volatils. Quelques travaux mentionnent son emploi dans un but preparatif. Les preparations des molecules organiques marquees sont effectuees habituellement sur des quantites de l'ordre de 1 a 10 millimoles. La chromatographie gazeuse a donc pu etre utilisee sans grande modification pour la purification de molecules marquees {sup 14}C et leur separation de melanges reactionnels complexes. Les appareils utilises seront brievement decrits. Les colonnes de chromatographie employees (diametre 9 a 12 mm, longueur 4 a 6 m environ) ont permis de separer des produits marques ayant des points d'ebullition jusqu'a 180 deg. C et en quantites de l'ordre de 100 mg a 1 g. Les fractions detectees par un dispositif classique a cellule de conductivite sont condensees dans des pieges refroidis par l'azote liquide. La mesure simultanee de la radioactivite n'a pas ete faite, une chambre d'ionisation pouvant fonctionner jusqu'a 220 deg. C etant seulement a l'etude. Dans tous les cas le gaz vecteur a ete l'helium, le support de phase stationnaire la 'Celite 545' 80 mesh le plus souvent. L'acetone {sup 14}C-2 resultant de la pyrolyse de l'acetate de baryum a ete purifiee sur une colonne de 'polyglycol 200'. L'eau et des impuretes non identifiees sont aisement eliminees. Le benzene C-6 resultant de la polymerisation cyclisante de l'acetylene {sup 14}C dans l'acetonitrile est separe quantitativement du melange reactionnel complexe sur une colonne de phtalate de nonyle a 80 deg. C. Les

  3. Contrast Dose and Radiation Dose Reduction in Abdominal Enhanced Computerized Tomography Scans with Single-phase Dual-energy Spectral Computerized Tomography Mode for Children with Solid Tumors

    OpenAIRE

    Tong Yu; Jun Gao; Zhi-Min Liu; Qi-Feng Zhang; Yong Liu; Ling Jiang; Yun Peng

    2017-01-01

    Background: Contrast dose and radiation dose reduction in computerized tomography (CT) scan for adult has been explored successfully, but there have been few studies on the application of low-concentration contrast in pediatric abdominal CT examinations. This was a feasibility study on the use of dual-energy spectral imaging and adaptive statistical iterative reconstruction (ASiR) for the reduction of radiation dose and iodine contrast dose in pediatric abdominal CT patients with solid tumors...

  4. Civili, langue des Baloango

    DEFF Research Database (Denmark)

    Mavoungou, Paul Achille; Ndinga-Koumba-Binza, Hugues Steve

    , Congo, Angola, etc.) issus de la décolonisation. Il présente de façon succincte quelques phénomènes historiques, phonologiques, morphosyntaxiques, homonymiques et analogiques de la langue. Des faits sémantiques des emprunts linguistiques y sont également décrits dans le cadre des changements...

  5. Des racines et des ailes

    Directory of Open Access Journals (Sweden)

    Stéphanie Vincent-Geslin

    2012-05-01

    Full Text Available Les mobilités pendulaires semblent être en augmentation en Europe depuis une dizaine d’années. Cette croissance du temps passé à se déplacer amène à remettre en question la conjecture de Zahavi et apparaît relativement inexplicable en regard du paradigme classique de l’acteur rationnel traditionnellement utilisé dans le champ des transports. Si, dans la littérature, les temps de déplacements sont principalement expliqués par le contexte résidentiel, la forme urbaine et le travail, ce cadre explicatif ne dit rien des processus de décision eux-mêmes qui amènent aux pendularités intensives.À partir d’une enquête qualitative menée auprès de pendulaires français, suisses et belges, cette contribution propose d’analyser les arbitrages et les éléments déterminants des processus de la grande pendularité. Les mobilités quotidiennes pendulaires apparaissent comme le résultat de compromis entre activité professionnelle, attachement résidentiel et choix de vie et prennent ainsi la forme de stratégies de conciliation entre vie privée et vie professionnelle. Ces mobilités spatiales permettent alors paradoxalement la préservation des ancrages résidentiels, sociaux et familiaux.Roots and wings. Long-distance commuting patterns, or how to conciliate professional and personal lifeLong-distance commuting patterns appear to be increasing in Europe over the last ten years. These raising mobility patterns lead to reappraise the Zahavi conjecture and appear largely inexplicable by the classical rational actor paradigm traditionally used in transportation research. In literature, commuting is mainly explained by residential contexts, urban forms and job. Nevertheless this theoretical frame says little about the decision-making processes themselves. Based on a qualitative survey conducted in three European countries - France, Belgium and Switzerland – among a population of high commuters, this paper proposes an analysis of

  6. Self diffusion and spectral modifications of a membrane protein, the Rubrivivax gelatinosus LH2 complex, incorporated into a monoolein cubic phase.

    OpenAIRE

    Tsapis, N; Reiss-Husson, F; Ober, R; Genest, M; Hodges, R S; Urbach, W

    2001-01-01

    The light-harvesting complex LH2 from a purple bacterium, Rubrivivax gelatinosus, has been incorporated into the Q230 cubic phase of monoolein. We measured the self-diffusion of LH2 in detergent solution and in the cubic phase by fluorescence recovery after photobleaching. We investigated also the absorption and fluorescence properties of this oligomeric membrane protein in the cubic phase, in comparison with its beta-octyl glucoside solution. In these experiments, native LH2 and LH2 labeled ...

  7. Prise en compte de la dimension finie des faisceaux d'éclairage en granulométrie optique: anémométrie phase Doppler

    OpenAIRE

    Onofri, Fabrice

    1995-01-01

    The optical diagnosis by phase Doppler anemometry of particles encountered in two­phase flows require the use of focused laser beams. The influence of the intensity gradients induced on the particle surface is considered in the first part of this manuscript. Several new phase Doppler geometries are proposed, enabling to suppress the errors induced by the so­called « trajectory effects ». The second part of this work deals with the extension of the phase Doppler anemometry to particle refracti...

  8. Le transfert de la direction des activités vers des institutions ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    la recherche-action participative (RAP);. • l'éducation et la formation;. • les communications et le ... financé des ateliers de formation en anglais et en français sur les méthodes de RAP, l'évaluation des risques ... En 2010, le programme ACCA a financé une deuxième phase de l'ACCFP qui sera dirigée par l'Institut d' ...

  9. La châine andine du Pérou Central: chronologie, orientation et styles des phases tectoniques du Tertiaire Supérieur - Aperçus sur la Tectonique Quaternaire

    Directory of Open Access Journals (Sweden)

    1975-01-01

    Full Text Available Les phases tectoniques mio-pliocènes sont étudiées dans plusieurs secteurs des Andes Centrales péruviennes. Au sud de Huancavelica (Choclococha, Huachocolpa, Lircay on note une phase de déformation cassante pliocène, selon une direction de raccourcissement N 090 (entre 8 et 4,5 M.A. Une phase miocène récent (entre 14 et 10,5 M. A de direction N 000 dans les Hauts Plateaux et peut-être de direction N 0.45 dans la Cordillère Occidentale donne des déformations cassantes mais avec une légère tectonique souple. La phase miocène ancien (entre 21 et 14 M.A est caractérisée par une direction N 0 45, des structures cassantes et de larges structures souples. La phase oligocène inférieur (entre 21,5 et 40 M.A concerne des efforts beaucoup plus importants dans des structures plus profondes. Les phases miocènes et pliocène sont superposées. L'étude de la faille de Gran-Bretaña confirme ces résultats sans que l'on puisse avoir la preuve de deux phases miocènes il s'agit d'un accident décrochant à faibles rejeux horizontaux. Les failles de la zone La Oroya, Junin, Tarma ont une géométrie semblable à l'accident de Gran-Bretaña: trois phases sont observables sans qu'il soit possible de les dater mais leurs caractéristiques correspondent aux phases pliocène, miocène et oligocène inférieur. Quelques observations dans la Cordillère Blanche semblent se rattacher à celles du Sud de Huancavelica, mais restent à préciser. Le Quaternaire montre une tectonique compressive de directions N 130 pour la Cordillère Blanche et San Ramón, N 000 et N 040 dans le bassin de Huancayo (éventuellement aussi N 075 suivant l'âge de la formation Jauja. Des failles normales n'ont été observées que dans la Cordillère Blanche (distension? montée du massif granitique?. Las fases tectónicas mio-pliocenas son estudiadas en muchos sectores de los Andes Centrales peruanos. Al sur de Huancavelica (en Choclococha, Huachocolpa, Lircay se nota una

  10. Effets des electrons secondaires sur l'ADN

    Science.gov (United States)

    Boudaiffa, Badia

    Les interactions des electrons de basse energie (EBE) representent un element important en sciences des radiations, particulierement, les sequences se produisant immediatement apres l'interaction de la radiation ionisante avec le milieu biologique. Il est bien connu que lorsque ces radiations deposent leur energie dans la cellule, elles produisent un grand nombre d'electrons secondaires (4 x 104/MeV), qui sont crees le long de la trace avec des energies cinetiques initiales bien inferieures a 20 eV. Cependant, il n'y a jamais eu de mesures directes demontrant l'interaction de ces electrons de tres basse energie avec l'ADN, du principalement aux difficultes experimentales imposees par la complexite du milieu biologique. Dans notre laboratoire, les dernieres annees ont ete consacrees a l'etude des phenomenes fondamentaux induits par impact des EBE sur differentes molecules simples (e.g., N2, CO, O2, H2O, NO, C2H 4, C6H6, C2H12) et quelques molecules complexes dans leur phase solide. D'autres travaux effectues recemment sur des bases de l'ADN et des oligonucleotides ont montre que les EBE produisent des bris moleculaires sur les biomolecules. Ces travaux nous ont permis d'elaborer des techniques pour mettre en evidence et comprendre les interactions fondamentales des EBE avec des molecules d'interet biologique, afin d'atteindre notre objectif majeur d'etudier l'effet direct de ces particules sur la molecule d'ADN. Les techniques de sciences des surfaces developpees et utilisees dans les etudes precitees peuvent etre etendues et combinees avec des methodes classiques de biologie pour etudier les dommages de l'ADN induits par l'impact des EBE. Nos experiences ont montre l'efficacite des electrons de 3--20 eV a induire des coupures simple et double brins dans l'ADN. Pour des energies inferieures a 15 eV, ces coupures sont induites par la localisation temporaire d'un electron sur une unite moleculaire de l'ADN, ce qui engendre la formation d'un ion negatif transitoire

  11. Two-phase flow in a saliniferous final repository using the example of ERAM. Final report; Zweiphasenfluss in einem salinaren Endlager am Beispiel des ERAM. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Kock, Ingo; Frieling, Gerd; Navarro, Martin

    2016-10-15

    In the frame of the research project ZIESEL the GRS enhanced the state of science and technology for the realization and evaluation of long-term safety cases for the final deposition of radioactive wastes. The superior aim was the improved understanding of two-phase flow processes in a complex final repository system. The consideration of two-phase processes in modeling of final repository systems induces processes and effects that significantly affect the transport behavior of fluid and radionuclides. Two-phase processes include not only capillary pressures and relative permeabilities but also a basic competition of phases with respect to pore volume for storage and transport and density-driven vertical separation of phases. Basically seals have been shown to be essential for the system behavior because of their influence of the gas pressure dependent control function. The system behavior is also influences by the model geometry.

  12. Modeling and numerical analysis of non-equilibrium two-phase flows; Modelisation et analyse numerique des ecoulements diphasiques en desequilibre

    Energy Technology Data Exchange (ETDEWEB)

    Rascle, P.; El Amine, K. [Electricite de France (EDF), Direction des Etudes et Recherches, 92 - Clamart (France)

    1997-12-31

    We are interested in the numerical approximation of two-fluid models of nonequilibrium two-phase flows described by six balance equations. We introduce an original splitting technique of the system of equations. This technique is derived in a way such that single phase Riemann solvers may be used: moreover, it allows a straightforward extension to various and detailed exchange source terms. The properties of the fluids are first approached by state equations of ideal gas type and then extended to real fluids. For the construction of numerical schemes , the hyperbolicity of the full system is not necessary. When based on suitable kinetic unwind schemes, the algorithm can compute flow regimes evolving from mixture to single phase flows and vice versa. The whole scheme preserves the physical features of all the variables which remain in the set of physical states. Several stiff numerical tests, such as phase separation and phase transition are displayed in order to highlight the efficiency of the proposed method. The document is a PhD thesis divided in 6 chapters and two annexes. They are entitled: 1. - Introduction (in French), 2. - Two-phase flow, modelling and hyperbolicity (in French), 3. - A numerical method using upwind schemes for the resolution of two-phase flows without exchange terms (in English), 4. - A numerical scheme for one-phase flow of real fluids (in English), 5. - An upwind numerical for non-equilibrium two-phase flows (in English), 6. - The treatment of boundary conditions (in English), A.1. The Perthame scheme (in English) and A.2. The Roe scheme (in English). 136 refs. This document represents a PhD thesis in the speciality Applied Mathematics presented par Khalid El Amine to the Universite Paris 6.

  13. Dosage direct des alcools dans les carburols par chromatographie en phase gazeuse Direct Gas Chromatographie Determination of Alcohols in Gasolines Blended by Oxygenated Compounds

    Directory of Open Access Journals (Sweden)

    Petroff N.

    2006-11-01

    Full Text Available Dans cette étude, on décrit une méthode de chromatographie en phase gazeuse utilisant une colonne remplie ; elle permet de doser, sans préfractionnement, les alcools jusqu'aux butanols dans les carburols (carburants additionnés de composés oxygénés. La phase stationnaire sélectionnée est le glycérol. This report describes a gas chromatographie method using a packed column. It allows the direct determination of alcohols up to butanols in gasolines blended with oxygenated compounds without prefractionation. Glycerol has been selected as stationary phase.

  14. Hydrogen in intermetallic phases: the system titanium--nickel--hydrogen. Wasserstoff in intermetallischen phasen am beispiel des systems titan-nickel-wasserftoff

    Energy Technology Data Exchange (ETDEWEB)

    Buchner, H.; Gutjahr, M. A.; Beccu, K. D.; Saeufferer, H.

    1972-07-01

    The intermetallic phases Ti/sub 2/-Ni (E9/sub 3/-type) and TiNi (B2-type) are able to absorb great amounts of hydrogen interstitially. The E9/sub 3/-structure forms four isotypic hydrogen phases, the lattice parameters of which increase with increasing hydrogen contents (..delta..d/sub max/ = 5.3%). The stoichiometric formulas are: Ti/sub 2/NiH/sub 0/./sub 5/; Ti/sub 2/NiH; Ti/sub 2/NiH/sub 2/; Ti/sub 2/NiH/sub 2/./sub 5/. The lattice parameter of the B2-structure increases from 3.01 A to 3.10 A (..delta..d = 3%), thus forming the stoichiometric TiNiH phase. The TiNiH structure possesses an eight-fold superlattice having a B2 type cell. The positions of hydrogen in the two intermetallic phases Ti/sub 2/Ni and TiNi are discussed from the geometrical point of view. Neutron diffraction diagrams verify these positions for only two hydrogen phases (Ti/sub 2/NiH/sub 0/./sub 5/; Ti/sub 2/NiH). Because of extreme experimental difficulties, the exact hydrogen positions in the phases Ti/sub 2/NiH/sub 2/; Ti/sub 2/NiH/sub 2/./sub 5/; TiNiH are still unknown.

  15. Methodes spectrales paralleles et applications aux simulations de couches de melange compressibles

    OpenAIRE

    Male , Jean-Michel; Fezoui , Loula ,

    1993-01-01

    La resolution des equations de Navier-Stokes en methodes spectrales pour des ecoulements compressibles peut etre assez gourmande en temps de calcul. On etudie donc ici la parallelisation d'un tel algorithme et son implantation sur une machine massivement parallele, la connection-machine CM-2. La methode spectrale s'adapte bien aux exigences du parallelisme massif, mais l'un des outils de base de cette methode, la transformee de Fourier rapide (lorsqu'elle doit etre appliquee sur les deux dime...

  16. Some Possibilities of Radiation Polymerization from the Gaseous Phase on Solid Bases; Possibilites de polymerisation radiochimique en phase gazeuse sur des lits de matiere solide; O nekotorykh vozmozhnostyakh radiatsionnoj polimerizatsii iz gazovoj fazy na tverdykh podlozhkakh; Perspectivas de la radiopolimerizacion en fase gaseosa sobre lechos de sustancias solidas

    Energy Technology Data Exchange (ETDEWEB)

    Tsetlin, B. L.

    1963-11-15

    The unusual feature of graft polymer synthesis by solid ''bed'' irradiation in the presence of monomer vapours is that the activation centres initiating polymerization are in practice generated only on the bed; transmission of the kinetic chain to the monomer is impeded and new polymer chains grow only under the influence of the solid bed molecular forces. These features of gas phase processes enlarge the scope of the graft polymer technique, making it applicable to inorganic beds and usable in the synthesis of mineral organic products. If stretched synthetic fibres are used as a bed, on the other hand, their orientated macromolecules control the growth of new polymer chains and the graft polymer is formed directly as an orientated structure. Two-component combined fibres are formed as a result and the fibre-bed and ''grafted'' fibre may in appropriate circumstances each display their own particular complex of mechanical properties. (author) [French] La synthese des polymeres greffes par irradiation de ''lits'' de matiere solide en presence de vapeur de monomeres en voie de polymerisation presente les particularites suivantes: les centres actifs qui amorcent la polymerisation ne se forment pratiquement qu'a la surface du ''lit''; le transfertau monomere de la chaine en mouvement est rendu plus difficile; les nouvelles chafnes du polymere se developpent sous l'action unilaterale des forces moleculaires de la surface solide. Ces particularites du processus en phase gazeuse elargissent les possibilites qu'offre la methode de la polymerisation par greffage. La methode peut alors etre egalement appliquee aux lits non organiques et servir a la synthese de composes organomineraux. En revanche, lorsqu'on utilise comme lits des fibres synthetiques allongees, les macromolecules orientees de ces dernieres dirigent la croissance des nouvelles chaines du polymere de sorte que le polymere greffe se forme directement a l'etat oriente. On obtient ainsi des fibres cominees a deux

  17. Logarithmic compression methods for spectral data

    Science.gov (United States)

    Dunham, Mark E.

    2003-01-01

    A method is provided for logarithmic compression, transmission, and expansion of spectral data. A log Gabor transformation is made of incoming time series data to output spectral phase and logarithmic magnitude values. The output phase and logarithmic magnitude values are compressed by selecting only magnitude values above a selected threshold and corresponding phase values to transmit compressed phase and logarithmic magnitude values. A reverse log Gabor transformation is then performed on the transmitted phase and logarithmic magnitude values to output transmitted time series data to a user.

  18. Spectral Imaging by Upconversion

    DEFF Research Database (Denmark)

    Dam, Jeppe Seidelin; Pedersen, Christian; Tidemand-Lichtenberg, Peter

    2011-01-01

    We present a method to obtain spectrally resolved images using upconversion. By this method an image is spectrally shifted from one spectral region to another wavelength. Since the process is spectrally sensitive it allows for a tailored spectral response. We believe this will allow standard...... silicon based cameras designed for visible/near infrared radiation to be used for spectral images in the mid infrared. This can lead to much lower costs for such imaging devices, and a better performance....

  19. Spectral Decomposition Algorithm (SDA)

    Data.gov (United States)

    National Aeronautics and Space Administration — Spectral Decomposition Algorithm (SDA) is an unsupervised feature extraction technique similar to PCA that was developed to better distinguish spectral features in...

  20. Des Connaissances Aux Politiques

    International Development Research Centre (IDRC) Digital Library (Canada)

    Les synergies ont été mises en commun au fur et à mesure des progrès de la recherche. .... Recherche normative (sur le rôle et la performance des institutions .... Système national d'information sur la gestion environnementale connecté à 19 ...... Un fort contrôle centralisé sur l'élaboration des politiques nationales peut ...

  1. Lattice dynamics, phase transition, and tunable fundamental band gap of photovoltaic (K,Ba)(Ni,Nb)O3 -δ ceramics from spectral measurements and first-principles calculations

    Science.gov (United States)

    Li, Chuanqian; Wang, Fang; Sun, Yuyun; Jiang, Kai; Gong, Shijing; Hu, Zhigao; Zhou, Zhiyong; Dong, Xianlin; Chu, Junhao

    2018-03-01

    Ferroelectrics have long been recognized as one of the candidate class of materials for applications in photovoltaic devices. Recently, ferroelectric perovskite (K,Ba) (Ni,Nb) O3 -δ has been successfully synthesized and demonstrated to have a near-optimal band gap (1.39 eV), exhibiting good photovoltaic performance. However, the connection between the structural order-disorder transformation, electronic structure, bulk photovoltaic, and photocatalytic properties remains not well understood. Here, we investigate the phase transition evolutions of lead-free [KNbO3]1-x[BaNi1/2Nb1/2O3 -δ] x (KBNNO x , x =0 -0.5 ) ceramics via x-ray diffraction (XRD), Raman scattering, and computational evidences. The lattice dynamics and the origin of the successive rhombohedral→orthorhombic→tetragonal→cubic phase transitions have been systemically explored based on temperature-dependent XRD peak positions and phonon modes under different geometries. Moreover, the differences in the phase transition temperature and interior structure between the solid solution x =0.2 and the end member x =0 highlight local and nonlocal characteristics, which are helpful for understanding the photovoltaic mechanisms. Additionally, the robust photocatalytic decoloration effect on methylene blue can further confirm the photon-generated carrier behavior in the partly structural disordered orthorhombic phase. This identification of structural phases, combined with the ability to perform photocatalytic decoloration, give some insights on promising oxide applications as semiconducting ferroelectric absorbers and carrier-separating layers in photocatalytic or photovoltaic devices.

  2. Poly-phase flows in the vicinity of wells in hydrocarbon deposits; Les ecoulements polyphasiques aux abords des puits dans les gisements d`hydrocarbures

    Energy Technology Data Exchange (ETDEWEB)

    Betata, S.A.

    1998-02-13

    During the production phase of an oil reservoir, a pressure drawdown occurs in the near wellbore region. This may lower the pressure below the bubble-point pressure, leading to the appearance of a gas phase, thus decreasing the oil relative permeability and the well productivity. The main goal of this study is the development of an appropriate laboratory procedure and its modeling, so as to derive gas-oil relative permeabilities at conditions representative of the near wellbore region, e.g. for a dispersed gas phase. A set of depressurization tests in porous media are performed for various conditions of pressure gradient and supersaturation. They are interpreted using a model relating the gas saturation to the supersaturation, as well as the nucleation rate J. Gas-oil relative permeabilities and average gas saturation versus time are measured. Oil relative permeabilities are found to be a function of both the gas saturation and the supersaturation. In addition to that, above a given threshold pressure drop part of the gas is mobilized. The value of J, obtained from the oil production curve leads to the description of the bubble population, in terms of their number and size. It is shown that oil-phase flow impairment is caused more by a limited number of large bubbles rather than by the presence of regularly distributed small ones. The procedure thus established allows the description of the behavior of oil and gas, not only above the critical gas saturation (defined as the saturation above which the gas phase becomes continuous), but also in the early stage of the nucleation, when the gas, even in a dispersed form, can flow depending on the applied pressure gradient. (author) 39 refs.

  3. Évaluation des pratiques agricoles des légumes feuilles : le cas des ...

    African Journals Online (AJOL)

    SARAH

    30 sept. 2017 ... ... de Biochimie et Immunologie Appliquée, Centre de Recherche en Sciences Biologiques, Alimentaires et .... l'intoxication des agriculteurs et des consommateurs, ... source d'alimentation en eau et au pouvoir d'achat des.

  4. Partitioning and transmutation of transuranium elements under nuclear phase-out conditions. Technically reliable?; Transmutation von Transuranen unter den Randbedingungen des Kernenergieausstiegs. Technisch machbar?

    Energy Technology Data Exchange (ETDEWEB)

    Merk, Bruno; Rohde, Ulrich [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany)

    2016-04-15

    The German government has decided for the nuclear phase out, but a decision on a strategy for the management of the highly radioactive waste is not defined yet. Partitioning and Transmutation (P and T) could be considered as a technological option in the process of management of highly radioactive waste management, therefore a wide study has been conducted. In this group objectives for P and T and the boundary conditions of the phase out have been discussed. The fulfillment of the given objectives is analyzed using simulations of molten salt reactors with fast neutron spectrum. It is shown that the efficient transmutation of all existing transuranium isotopes would be possible in 3 to 4 reactors in a time frame of 45 to 60 years. Further on a detailed balance of different isotopic inventories is given to allow a deeper understanding of the processes during transmutation.

  5. The Importance of Water-Hydrocarbon Phase Equilibria During Reservoir Production and Drilling Operations Nouveaux défis liés à la présence d'équilibres eau-hydrocarbures lors des opérations de production et de forage

    Directory of Open Access Journals (Sweden)

    Zhou H.

    2006-12-01

    érature crée de nouveaux défis pour l'ingénieur pétrolier. Un bref état de l'art des équilibres eau-hydrocarbures est présenté dans un premier temps. À haute température, de grandes quantités d'eau peuvent se trouver dans la phase hydrocarbonée (jusqu'à 10% moles, et à haute pression, on trouvera des quantités non négligeables de gaz dissous dans l'eau. Des mesures de solubilités mutuelles ont donné lieu à un grand nombre de modèles. Étant donné les limites des données expérimentales, les restrictions des modèles sont soulignées. Des études récentes ont indiqué l'intérêt d'utiliser des constantes de Henry pour la prédiction de la solubilité d'hydrocarbures dans l'eau. Les nouveaux défis sont abordés sur la base de quelques publications récentes. L'eau présente en phase hydrocarbonée peut conduire à des dépôts de sels autour du puits, et peut modifier l'estimation de la quantité de gaz en place. Elle peut également donner lieu à une modification des pressions de saturation. La présence d'eau dans les conduites de transport impose un traitement supplémentaire pour éviter la formation d'hydrates. Les hydrocarbures dissous en phase aqueuse peuvent, de leur côté, modifier la composition du fluide, particulièrement lorsque la pression devient très faible. La toxicité de l'eau contenant du H2S ou des aromatiques peut créer de réels problèmes lorsqu'il s'agit de nappes aquifères ou lorsqu'il est question de rejeter les eaux de production. Lors du forage, la présence de gaz dissous dans le fluide de forage (souvent à base d'eau peut représenter un danger réel en causant des éruptions. Une attention particulière doit être portée aux injections de gaz acides dans des réservoirs, car l'effet de ces fluides injectés peut être difficile à prédire. En conclusion, au vu des besoins industriels présentés, des suggestions sont proposées pour des acquisitions de données supplémentaires ou pour améliorer les mod

  6. Theory of longitudinal atomic beam spin echo and parity violating Berry-phases in atoms; Theorie des longitudinalen Atomstrahl-Spinechos und paritaetsverletzende Berry-Phasen in Atomen

    Energy Technology Data Exchange (ETDEWEB)

    Bergmann, T.F.

    2006-07-19

    We present a nonrelativistic theory for the quantum mechanical description of longitudinal atomic beam spin echo experiments, where a beam of neutral atoms is subjected to static electric and magnetic fields. The atomic wave function is the solution of a matrix-valued Schroedinger equation and can be written as superposition of local (atomic) eigenstates of the potential matrix. The position- and time-dependent amplitude function of each eigenstate represents an atomic wave packet and can be calculated in a series expansion with a master formula that we derive. The zeroth order of this series expansion describes the adiabatic limit, whereas the higher order contributions contain the mixing of the eigenstates and the corresponding amplitude functions. We give a tutorial for the theoretical description of longitudinal atomic beam spin echo experiments and for the so-called Fahrplan model, which is a visualisation tool for the propagation of wave packets of different atomic eigenstates. As an example for the application of our theory, we study parity violating geometric (Berry-)phases. In this context, we define geometric flux densities, which for certain field configurations can be used to illustrate geometric phases in a vector diagram. Considering an example with a specific field configuration, we prove the existence of a parity violating geometric phase. (orig.)

  7. Angle of arrival estimation using spectral interferometry

    International Nuclear Information System (INIS)

    Barber, Z.W.; Harrington, C.; Thiel, C.W.; Babbitt, W.R.; Krishna Mohan, R.

    2010-01-01

    We have developed a correlative signal processing concept based on a Mach-Zehnder interferometer and spatial-spectral (S2) materials that enables direct mapping of RF spectral phase as well as power spectral recording. This configuration can be used for precise frequency resolved time delay estimation between signals received by a phased antenna array system that in turn could be utilized to estimate the angle of arrival. We present an analytical theoretical model and a proof-of-principle demonstration of the concept of time difference of arrival estimation with a cryogenically cooled Tm:YAG crystal that operates on microwave signals modulated onto a stabilized optical carrier at 793 nm.

  8. Angle of arrival estimation using spectral interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Z.W.; Harrington, C.; Thiel, C.W.; Babbitt, W.R. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Krishna Mohan, R., E-mail: krishna@spectrum.montana.ed [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States)

    2010-09-15

    We have developed a correlative signal processing concept based on a Mach-Zehnder interferometer and spatial-spectral (S2) materials that enables direct mapping of RF spectral phase as well as power spectral recording. This configuration can be used for precise frequency resolved time delay estimation between signals received by a phased antenna array system that in turn could be utilized to estimate the angle of arrival. We present an analytical theoretical model and a proof-of-principle demonstration of the concept of time difference of arrival estimation with a cryogenically cooled Tm:YAG crystal that operates on microwave signals modulated onto a stabilized optical carrier at 793 nm.

  9. Gestion des risques

    CERN Document Server

    Louisot, Jean-Paul

    2009-01-01

    Depuis le début du lie siècle, la gestion des risques connaît une véritable révolution culturelle. Jusqu'alors fonction technique, centrée autour de l'achat de couverture d'assurances, elle est devenue une discipline managériale et transversale : une valise d'instruments que chaque manager doit connaître et appliquer quels que soient son domaine de compétence et ses missions au sein de l'organisation. En effet, la gestion des risques est une culture qui doit être assimilée par chacun des acteurs. C'est précisément l'ambition des 101 questions rassemblées dans cet ouvrage : apporter à chaque manager d'entreprise, de collectivité, d'établissement de santé..., des réponses claires au " pourquoi " et au " comment " : Comment identifier les risques ? Comment analyser les risques ? Quels sont les objectifs de la gestion des risques ? Une carte des risques pour quoi faire ? Pourquoi faut-il financer les risques ? Les entreprises ont-elles des responsabilités pénales ? En quoi consiste la gestion...

  10. La gouvernance des risques naturels et la problematique des ...

    African Journals Online (AJOL)

    Depuis quelques années, la gouvernance des risques naturels dus aux inondations remet en cause les processus de mise en oeuvre des politiques urbaines et la qualité de la structure des aménagements dans les grandes villes du Golfe de Guinée. La perception de la gouvernance et l'application des politiques de ...

  11. Stochastic shock response spectrum decomposition method based on probabilistic definitions of temporal peak acceleration, spectral energy, and phase lag distributions of mechanical impact pyrotechnic shock test data

    Science.gov (United States)

    Hwang, James Ho-Jin; Duran, Adam

    2016-08-01

    Most of the times pyrotechnic shock design and test requirements for space systems are provided in Shock Response Spectrum (SRS) without the input time history. Since the SRS does not describe the input or the environment, a decomposition method is used to obtain the source time history. The main objective of this paper is to develop a decomposition method producing input time histories that can satisfy the SRS requirement based on the pyrotechnic shock test data measured from a mechanical impact test apparatus. At the heart of this decomposition method is the statistical representation of the pyrotechnic shock test data measured from the MIT Lincoln Laboratory (LL) designed Universal Pyrotechnic Shock Simulator (UPSS). Each pyrotechnic shock test data measured at the interface of a test unit has been analyzed to produce the temporal peak acceleration, Root Mean Square (RMS) acceleration, and the phase lag at each band center frequency. Maximum SRS of each filtered time history has been calculated to produce a relationship between the input and the response. Two new definitions are proposed as a result. The Peak Ratio (PR) is defined as the ratio between the maximum SRS and the temporal peak acceleration at each band center frequency. The ratio between the maximum SRS and the RMS acceleration is defined as the Energy Ratio (ER) at each band center frequency. Phase lag is estimated based on the time delay between the temporal peak acceleration at each band center frequency and the peak acceleration at the lowest band center frequency. This stochastic process has been applied to more than one hundred pyrotechnic shock test data to produce probabilistic definitions of the PR, ER, and the phase lag. The SRS is decomposed at each band center frequency using damped sinusoids with the PR and the decays obtained by matching the ER of the damped sinusoids to the ER of the test data. The final step in this stochastic SRS decomposition process is the Monte Carlo (MC

  12. Etude d'un modele de Boltzmann sur reseau pour la simulation assistee par ordinateur des fluides a plusieurs phases immiscibles

    Science.gov (United States)

    Leclaire, Sebastien

    The computer assisted simulation of the dynamics of fluid flow has been a highly rewarding topic of research for several decades now, in terms of the number of scientific problems that have been solved as a result, both in the academic world and in industry. In the fluid dynamics field, simulating multiphase immiscible fluid flow remains a challenge, because of the complexity of the interactions at the flow phase interfaces. Various numerical methods are available to study these phenomena, and, the lattice Boltzmann method has been shown in recent years to be well adapted to solving this type of complex flow. In this thesis, a lattice Boltzmann model for the simulation of two-phase immiscible flows is studied. The main objective of the thesis is to develop this promising method further, with a view to enhancing its validity. To achieve this objective, the research is divided into five distinct themes. The first two focus on correcting some of the deficiencies of the original model. The third generalizes the model to support the simulation of N-phase immiscible fluid flows. The fourth is aimed at modifying the model itself, to enable the simulation of immiscible fluid flows in which the density of the phases varies. With the lattice Boltzmann class of models studied here, this density variation has been inadequately modeled, and, after 20 years, the issue still has not been resolved. The fifth, which complements this thesis, is connected with the lattice Boltzmann method, in that it generalizes the theory of 2D and 3D isotropic gradients for a high order of spatial precision. These themes have each been the subject of a scientific article, as listed in the appendix to this thesis, and together they constitute a synthesis that explains the links between the articles, as well as their scientific contributions, and satisfy the main objective of this research. Globally, a number of qualitative and quantitative test cases based on the theory of multiphase fluid flows

  13. Structure of the amplitude equation of the climate; Struktur der Amplitudengleichung des Klimas

    Energy Technology Data Exchange (ETDEWEB)

    Hauschild, A. [Freie Univ. Berlin (Germany). Inst. fuer Meteorologie

    1999-04-01

    The structure of the `amplitude equation`, a new dynamic equation on the seasonal time scale is derived, in which the weather scales may be treated statistically. The elsewhere-introduced climate-specific seasonally smoothed amplitudes and phases of the Fourier spectral representation are used as new prognostic variables. For the vorticity it is shown, that the still unsolved problem of the parameterisation of subscale transports may be solved in the `amplitude equation`. The approach could be successful because of the empirically derived statistical properties of the amplitudes (Poisson distribution and ergodicity) and of the phases (equipartition) of sub-planetary waves could be used. They allow a scale separation of weather and climate and lead to a tremendous reduction of the number of the horizontal degree of freedom of the amplitude equation to be between 10{sup 3} and 10{sup 4}. (orig.) [Deutsch] Es wird die Struktur der `Amplitudengleichung`, einer neuen dynamischen Gleichung auf der saisonalen Zeitskala abgeleitet. Anhand analysierter Daten des EZMW wird gezeigt, dass in der `Amplitudengleichung` die explizite Dynamik des Wetters tatsaechlich statistisch behandelt werden kann. Als prognostische Variablen der Gleichung werden die woanders neu eingefuehrten, klimaspezifischen, saisonal geglaetteten Amplituden und Phasen der Fourier-Spektraldarstellung verwendet. Am Beispiel der Vorticity wird gezeigt, dass das bisher ungeloeste Problem der Behandlung der subskaligen Transporte in der `Amplitudengleichung` grundsaetzlich geloest werden kann. Dies gelingt durch Ausnutzung der ebenfalls empirisch abgeleiteten besonderen statistischen Eigenschaften der Amplituden (Poissonverteilung und Ergodizitaet) und Phasen (Gleichverteilung) der subplanetaren Wellen, die eine Skalentrennung von Wetter und Klima ermoeglichen. Dies fuehrt zur erheblichen Reduktion der Zahl der horizontalen Freiheitsgrade der Amplitudengleichung auf 10{sup 3} bis 10{sup 4}. Die Ableitung

  14. Phase and group refractive index curves for electromagnet waves moving in an ionised medium (1962); Courbes des indices de phase et de groupe d'ondes electromagnetiques se propageant dans un milieu ionise (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Consoli, T [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    The family of curves presented in this table give the phase and group refractive indexes of plane electromagnetic waves propagating along and across a static magnetic field in a plasma. (author) [French] Les courbes presentees sous formes de reseaux donnent les indices de phase et de groupe d'ondes electromagnetiques planes se propageant longitudinalement ou transversalement dans un plasma en presence d'un champ magnetique statique. (auteur)

  15. La quête des températures ultrabasses

    OpenAIRE

    Suchet , Daniel

    2018-01-01

    International audience; Des vendeurs de glace à l'industrie cryogénique, le froid est souvent perçu comme un produit. Pour le physicien, le froid, réduction de l'agitation aléatoire des particules, apparaît plutôt comme une force productrice, capable de faire émerger des structures complexes et de métamorphoser les propriétés des objets. Les basses températures ont été l'enjeu d'une course effrénée dont la première phase a pris fin en 1908 avec la liquéfaction de l'ensemble des gaz connus. Lo...

  16. Organisation des travaux ST-CV

    CERN Document Server

    Martel, C; CERN. Geneva. ST Division

    2003-01-01

    Débutée il y a deux ans, la phase de construction des installations de refroidissement du LHC a atteint en 2003 son apogée. De nombreux autres projets sont également gérés par le groupe dans divers secteurs du laboratoire. La spécificité du groupe est de réaliser des installations complexes impliquant des spécificités diverses telles qu’aéraulique, hydraulique, électrique, etc. Pour faire face à ces demandes la section travaux du groupe ST CV a adopté une structure capable de réaliser ces divers projets avec un minimum de personnel. La première partie de ce document décrit l’organisation de la section travaux ST CV. Dans une deuxième partie, les auteurs dressent un état des lieux des chantiers par projet en décrivant plus particulièrement les activités dans les domaines du traitement d’air et de refroidissement par eau.

  17. Le Phénomène Wolf-Rayet au Sein des Etoiles chaudes de Populations I et II: Histoire des Vents stellaires et Impact sur la Structure nébulaire circumstellaire

    Science.gov (United States)

    Grosdidier, Yves

    2000-12-01

    Les spectres des étoiles Wolf-Rayet pop. I (WR) présentent de larges raies en émission dues à des vents stellaires chauds en expansion rapide (vitesse terminale de l'ordre de 1000 km/s). Le modèle standard des étoiles WR reproduit qualitativement le profil général et l'intensité des raies observées. Mais la spectroscopie intensive à moyenne résolution de ces étoiles révèle l'existence de variations stochastiques dans les raies (sous-pics mobiles en accélération échelles de temps: environ 10-100 min.). Ces variations ne sont pas comprises dans le cadre du modèle standard et suggèrent une fragmentation intrinsèque des vents. Cette thèse de doctorat présente une étude de la variabilité des raies spectrales en émission des étoiles WR pop. II; la question de l'impact d'un vent WR fragmenté sur le milieu circumstellaire est aussi étudiée: 1) à partir du suivi spectroscopique intensif des raies CIIIl5696 et CIVl5801/12, nous analysons quantitativement (via le calcul des Spectres de Variance Temporelle) les vents issus de 5 étoiles centrales de nébuleuses planétaires (NP) galactiques présentant le phénomène WR; 2) nous étudions l'impact de la fragmentation des vents issus de deux étoiles WR pop. I sur le milieu circumstellaire via: i) l'imagerie IR (NICMOS2/HST) de WR 137, et ii) l'imagerie H-alpha (WFPC2/HST) et l'interférométrie Fabry-Perot H-alpha (SIS-CFHT) de la nébuleuse M 1-67 (étoile centrale: WR 124). Les principaux résultats sont les suivants: VENTS WR POP. II: (1) Nous démontrons la variabilité spectroscopique intrinsèque des vents issus des noyaux de NP HD 826 ([WC 8]), BD +30 3639 ([WC 9]) et LSS 3169 ([WC 9]), observés durant respectivement 22, 15 et 1 nuits, et rapportons des indications de variabilité pour les noyaux [WC 9] HD 167362 et He 2-142. Les variabilités de HD 826 et BD +30 3639 apparaissent parfois plus soutenues (``bursts'' qui se maintiennent durant plusieurs nuits); (2) La cinématique des sous

  18. Temperature measurements in fluid flows (eventually reactive, multi-phase...) using optical methods; Mesure des temperatures dans les ecoulements (eventuellement reactifs, multiphasiques...) par methodes optiques

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-12-31

    This conference day was organized by the `radiations` section of the French association of thermal engineers. This book of proceedings contains 8 papers entitled: `simultaneous temperature and NO concentration measurements in a hydrogen-air turbulent flame`; `application of iodine laser induced fluorescence to temperature, pressure and velocity measurements`; `Doppler phase measurement of refractive index and temperature`; `experimental and numerical study of temperature fields of particulates in plasma jets`; `measurement and determination of temperatures and concentrations of hot exhaust gases with FTIR emission spectroscopy`; `combustion control in gas turbines using CO{sub 2} emission spectroscopy`; `analysis of gases temperature fields and particulate jets. Application to hydrogen-air, kerosene stato-reactors and to solid propellant jets`; `restitution of temperature and species profiles in pre-mixing flames by inversion of transmission and IR emission data. (J.S.)

  19. Temperature measurements in fluid flows (eventually reactive, multi-phase...) using optical methods; Mesure des temperatures dans les ecoulements (eventuellement reactifs, multiphasiques...) par methodes optiques

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    This conference day was organized by the `radiations` section of the French association of thermal engineers. This book of proceedings contains 8 papers entitled: `simultaneous temperature and NO concentration measurements in a hydrogen-air turbulent flame`; `application of iodine laser induced fluorescence to temperature, pressure and velocity measurements`; `Doppler phase measurement of refractive index and temperature`; `experimental and numerical study of temperature fields of particulates in plasma jets`; `measurement and determination of temperatures and concentrations of hot exhaust gases with FTIR emission spectroscopy`; `combustion control in gas turbines using CO{sub 2} emission spectroscopy`; `analysis of gases temperature fields and particulate jets. Application to hydrogen-air, kerosene stato-reactors and to solid propellant jets`; `restitution of temperature and species profiles in pre-mixing flames by inversion of transmission and IR emission data. (J.S.)

  20. Virtual Monoenergetic Images From a Novel Dual-Layer Spectral Detector Computed Tomography Scanner in Portal Venous Phase: Adjusted Window Settings Depending on Assessment Focus Are Essential for Image Interpretation.

    Science.gov (United States)

    Hickethier, Tilman; Iuga, Andra-Iza; Lennartz, Simon; Hauger, Myriam; Byrtus, Jonathan; Luetkens, Julian A; Haneder, Stefan; Maintz, David; Doerner, Jonas

    We aimed to determine optimal window settings for conventional polyenergetic (PolyE) and virtual monoenergetic images (MonoE) derived from abdominal portal venous phase computed tomography (CT) examinations on a novel dual-layer spectral-detector CT (SDCT). From 50 patients, SDCT data sets MonoE at 40 kiloelectron volt as well as PolyE were reconstructed and best individual window width and level values manually were assessed separately for evaluation of abdominal arteries as well as for liver lesions. Via regression analysis, optimized individual values were mathematically calculated. Subjective image quality parameters, vessel, and liver lesion diameters were measured to determine influences of different W/L settings. Attenuation and contrast-to-noise values were significantly higher in MonoE compared with PolyE. Compared with standard settings, almost all adjusted W/L settings varied significantly and yielded higher subjective scoring. No differences were found between manually adjusted and mathematically calculated W/L settings. PolyE and MonoE from abdominal portal venous phase SDCT examinations require appropriate W/L settings depending on reconstruction technique and assessment focus.

  1. Photonique des Morphos

    CERN Document Server

    Berthier, Serge

    2010-01-01

    La photonique est déjà présente dans notre vie quotidienne, et on attend maintenant que la manipulation des photons permette aussi le traitement logique des informations. Cependant, l’élément de base qui permet cette manipulation de la lumière, le cristal photonique, est d’une réalisation complexe et mal contrôlée. Dans la course à la maîtrise de la lumière, les structures photoniques naturelles ont beaucoup à nous apprendre. C’est ce que nous montre Serge Berthier qui étudie dans ce livre la structure des écailles des Morphos. Tenant compte de l’essor récent des approches biomimétiques, il présente de manière détaillée plus de dix-huit techniques expérimentales utilisées pour ses analyses, ainsi que les diverses approches théoriques développées pour la modélisation de structures multi-échelles complexes. Première étude quasi-exhaustive des structures fines d’un genre et des propriétés optiques ainsi que colorimétriques générées, ce livre fournit aux entomologiste...

  2. Droit des organisations internationales

    CERN Document Server

    Sorel, Jean-Marc; Ndior, Valère

    2013-01-01

    Cet ouvrage collectif offre aux enseignants et chercheurs en droit international, aux praticiens et aux étudiants, une analyse actualisée du droit des organisations internationales. Il dresse en cinq parties un tableau, illustré par des exemples variés, des problématiques que soulève le phénomène polymorphe d institutionnalisation de la société internationale. La première partie est consacrée au phénomène des « organisations internationales », sous l angle à la fois de l institutionnalisation progressive des relations internationales et de la difficulté à cerner une catégorie unifiée. La deuxième partie rend compte de la création, de la disparition et des mutations des organisations internationales, ici envisagées comme systèmes institutionnels et ordres juridiques dérivés. La troisième partie analyse l autonomie que l acquisition de la personnalité juridique et de privilèges et immunités, un organe administratif intégré, un personnel ou un budget propres confèrent aux organi...

  3. Characterization and control of the electro-optic phase dispersion in lithium niobate modulators for wide spectral band interferometry applications in the mid-infrared.

    Science.gov (United States)

    Heidmann, S; Ulliac, G; Courjal, N; Martin, G

    2017-05-10

    Mid-infrared wideband modulation (3.2-3.7 μm) is achieved in an electro-optic Y-junction using lithium niobate waveguides in TE polarized light. Comparison between external (scanning mirror) and internal (electro-optical) modulation allows studying the chromatic polynomial dependence of the relative phase. Internal modulation consists on a V AC ramp up to 370 V at 0.25 Hz, applied over 14 mm long electrodes with 14 μm separation. The overall V π L π obtained is 17.5 V·cm, meaning that using a 300 V generator we can actively scan and track the whole L-band (3.4-4.1 μm) wideband fringes. We observe a dramatic reduction of the coherence length under electro-optic modulation, which is attributed to a strong nonlinear dependence of the electro-optic effect on the wavelength upon application of such high voltages. We study the effect of applying a V DC offset, from -50  V to 200 V (50 V step). We characterize this dispersion and propose an improved dispersion model that is used to show active dispersion compensation in wideband fringe modulation in the mid-infrared. This can be useful for long baseline interferometry or pulse compression applications when light propagates along fibers, in order to compensate for chromatic effects that induce differential dispersion or pulse spreading, respectively.

  4. Spectral Learning for Supervised Topic Models.

    Science.gov (United States)

    Ren, Yong; Wang, Yining; Zhu, Jun

    2018-03-01

    Supervised topic models simultaneously model the latent topic structure of large collections of documents and a response variable associated with each document. Existing inference methods are based on variational approximation or Monte Carlo sampling, which often suffers from the local minimum defect. Spectral methods have been applied to learn unsupervised topic models, such as latent Dirichlet allocation (LDA), with provable guarantees. This paper investigates the possibility of applying spectral methods to recover the parameters of supervised LDA (sLDA). We first present a two-stage spectral method, which recovers the parameters of LDA followed by a power update method to recover the regression model parameters. Then, we further present a single-phase spectral algorithm to jointly recover the topic distribution matrix as well as the regression weights. Our spectral algorithms are provably correct and computationally efficient. We prove a sample complexity bound for each algorithm and subsequently derive a sufficient condition for the identifiability of sLDA. Thorough experiments on synthetic and real-world datasets verify the theory and demonstrate the practical effectiveness of the spectral algorithms. In fact, our results on a large-scale review rating dataset demonstrate that our single-phase spectral algorithm alone gets comparable or even better performance than state-of-the-art methods, while previous work on spectral methods has rarely reported such promising performance.

  5. Up scaling two-phase flow in heterogeneous porous media; Mise a l'echelle des ecoulements diphasiques dans les milieux poreux heterogenes

    Energy Technology Data Exchange (ETDEWEB)

    Artus, V.

    2003-11-01

    For two-phase flow in heterogeneous media, the emergence of different flow regimes at large-scale is driven by local interactions between the viscous coupling and the heterogeneity. In particular, when the viscosity ratio is favorable, viscous effects induce a transverse flow that stabilizes the front while flooding. However, most of recent stochastic models neglect the influence of the viscous coupling. We developed a stochastic model for the dynamics of the front, taking the viscous coupling into account. For stable cases, this model relates the statistical properties of the front to the statistical properties of the permeability field. For stable flow in stratified media, we show that the front is stationary by parts in the reservoir. These parts can be identified as large-scale hydrodynamic layers and separately coarsened in the large-scale simulation model. For flows with favorable viscosity ratios in isotropic reservoirs, we show that a stationary front occurs, in a statistical sense. For unfavorable viscosity ratios, the flow is driven by the development of viscous fingering. These different regimes lead to different large-scale saturation profiles that can be matched with a macro-dispersion equation, if the effective convective flux is modified to take into account stabilizing or destabilizing viscous effects. (author)

  6. Dependence on Solar Phase Angle and Grain Size of the Spectral Reflectance of the Railroad Valley Playa for GOSAT/GOSAT-2 Vicarious Calibration

    Science.gov (United States)

    Arai, T.; Matsunaga, T.

    2017-12-01

    GOSAT and the next generation GOSAT-2 satellites estimate the concentration of greenhouse gasses, and distribution of aerosol and cloud to observe solar light reflection and radiation from surface and atmosphere of the Earth. Precise information of the surface and the bidirectional reflectance distribution function (BRDF) are required for the estimation because the surface reflectance of solar light varies with the observation geometry and the surface condition. The purpose of this study is to search an appropriate BRDF model of the GOSAT calibration site (Railroad Valley playa). In 2017, JAXA, NIES, and NASA/OCO-2 teams collaboratively performed 9th vicarious experiments by the simultaneous observation with GOSAT, OCO-2, and ground-based equipment (Kuze et al., 2014) at the Railroad Valley from June 25 to 30. We performed the BRDF measurement to observe solar light reflection by varying with observed angles using a spectroradiometer (FieldSpec4, ASD Inc.) mounted on a one-axis goniometer. The surface sand was shifted to several sizes of grain (75, 125, 250, 500, and 1000 μm), which was measured for the limited area of 5mm diameter with a collimating lens (74-UV, OceanOptics). The BRDF parameters for the observed reflectance were determined by the least squares fitting with the free parameters of a single scattering albedo and an asymmetric factor (Hapke, 2012) for the ultraviolet to near infrared wavelength bands of GOSAT. The resulting value of the single scattering albedo increased with decreasing the grain size of the sands. The observed reflectance of the fine grain sands (below 250 μm) is not varied with observed phase angles (solar incident light - surface sand - detector) as a Lambertian reflectance, but the spectra of coarse grain sands (above 500 μm) are varied with the observation angles. Therefore, a priori information of the target surface such as grain size is required for the determination of the precise reflectance of the target.

  7. Spectral gamuts and spectral gamut mapping

    Science.gov (United States)

    Rosen, Mitchell R.; Derhak, Maxim W.

    2006-01-01

    All imaging devices have two gamuts: the stimulus gamut and the response gamut. The response gamut of a print engine is typically described in CIE colorimetry units, a system derived to quantify human color response. More fundamental than colorimetric gamuts are spectral gamuts, based on radiance, reflectance or transmittance units. Spectral gamuts depend on the physics of light or on how materials interact with light and do not involve the human's photoreceptor integration or brain processing. Methods for visualizing a spectral gamut raise challenges as do considerations of how to utilize such a data-set for producing superior color reproductions. Recent work has described a transformation of spectra reduced to 6-dimensions called LabPQR. LabPQR was designed as a hybrid space with three explicit colorimetric axes and three additional spectral reconstruction axes. In this paper spectral gamuts are discussed making use of LabPQR. Also, spectral gamut mapping is considered in light of the colorimetric-spectral duality of the LabPQR space.

  8. Santé des adolescents et des jeunes au Burkina Faso : état des ...

    African Journals Online (AJOL)

    Il s'est agi d'une étude évaluative ayant utilisé une revue documentaire associée à une interview des acteurs clés et un atelier de validation et d'identification des interventions pertinentes pour un plan stratégique national. La situation de la santé des adolescents et des jeunes est caractérisée par des grossesses précoces ...

  9. Contribution to the study of the sintering of ex-carbonyl iron in the {alpha} and {gamma} phases using the micro-fractographic technique; Contribution a l'etude du frittage du fer ex-carbonyle en phases {alpha} et {gamma} par examen des surfaces de rupture au microscope electronique

    Energy Technology Data Exchange (ETDEWEB)

    Oxley Gaborit de Montjou, M.Th. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-07-01

    The micro-fractographic study of the sintering of ex-carbonyl iron has shown or confirmed a number of phenomena of which the principal are as followed: Sintering in the a phase: -) existence of two stages of sintering differentiated by the type of rupture (inter or trans-crystalline); -) marked influence of the content of oxygen in the atmosphere and in the initial compressed sample on the speed of sintering; -) formation of striations on the grain-boundary surfaces and on the inner surface of pores caused by the presence of oxygen. Sintering in the {gamma} phase: -) a pronounced decrease in the speed of sintering: the grains in the initial powder remain in the granular state within the final {alpha} crystal in the iron sintered in the lower {gamma} range even after several hours of sintering; -) this granular structure can be eliminated by intermediate compression thus enabling the sintering process to proceed. A considerable decrease in the speed of sintering if the A{sub 3} point is passed one or more times in the {alpha} range sintering. A high speed sintering if the treatment in the {gamma} range is carried out at or above 1300 C. The results of this study agree with micrographic investigation as well as with dilatometric measurements and known auto-diffusion coefficients. (author) [French] L'etude microfractographique du frittage du fer ex-carbonyle a permis de mettre en evidence ou verifier plusieurs phenomenes dont les principaux sont les suivants: Pour le frittoge en phase {alpha}: -) existence de deux stades de frittage differencies par le type de rupture (inter et transcristalline); -) importance de la teneur en oxygene dans l'atmosphere et dans le comprime initial sur la vitesse de frittage; -) formation de stries dues a la presence d'oxygene sur les plans de joints et a l'interieur des pores. Pour le frittage en phase {gamma}: -) un ralentissement tres prononce de la cinetique du frittage: les granules de la poudre initiale demeurent a l'etat de

  10. Dental Encounter System (DES)

    Data.gov (United States)

    Department of Veterans Affairs — Dental Encounter System (DES) is an automated health care application designed to capture critical data about the operations of VA Dental Services. Information on...

  11. Diethylstilbestrol (DES) and Cancer

    Science.gov (United States)

    ... DES-exposed grandchildren have? Researchers are also studying possible health effects among women and men who are the children ... for unexposed men. In addition, researchers are studying possible health effects on the grandchildren of mothers who were exposed ...

  12. Table des illustrations

    OpenAIRE

    2016-01-01

    Tableaux Dates d’inauguration des grands hôtels japonais entre 1860 et 1945… 19 Histoire, tourisme et hôtellerie en Corée depuis les années 1870… 59-60 Dates d’inauguration des grands hôtels chinois depuis 1863… 84 Les hôtels de luxe et leurs capacités d’hébergement en Corée en 2000… 103 Les flux de personnes suscités par les hôtels « super luxe » de Séoul en 2000… 105 L’activité des grands hôtels à Séoul en 1999 (en wons)… 106 Propriété et gestion des grands hôtels à Séoul en 1999…. 110 La c...

  13. Direction des Publications

    African Journals Online (AJOL)

    Synthese

    potential and surface properties of their mixtures were investigated, in an ... suppose that the electrostatic repulsive interactions between the two anion ... concentration, et de la conformation des ..... proteins and polysaccharides in solutions,.

  14. Evaluation of dual energy spectral CT in differentiating metastatic from non-metastatic lymph nodes in rectal cancer: Initial experience

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Huanhuan [Department of Radiology, Ruijin Hospital Affiliated to Shanghai Jiaotong University, School of Medicine, Shanghai 200025 (China); Department of Radiology, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine (China); Yan, Fuhua; Pan, Zilai; Lin, Xiaozhu; Luo, Xianfu; Shi, Cen [Department of Radiology, Ruijin Hospital Affiliated to Shanghai Jiaotong University, School of Medicine, Shanghai 200025 (China); Chen, Xiaoyan [Department of Pathology, Ruijin Hospital Affiliated to Shanghai Jiaotong University, School of Medicine, Shanghai 200025 (China); Wang, Baisong [Department of Biomedical Statistics, Shanghai Jiaotong University, School of Medicine, Shanghai 200025 (China); Zhang, Huan, E-mail: huanzhangy@126.com [Department of Radiology, Ruijin Hospital Affiliated to Shanghai Jiaotong University, School of Medicine, Shanghai 200025 (China)

    2015-02-15

    Highlights: • Colorectal cancer is the third most prevalent cancer and the status of the regional lymph nodes in rectal cancer is considered to be one of the most powerful prognostic factor in the absence of distant metastatic disease. Detecting LNs metastasis is still a challenging problem due to the presence of microscopic metastasis or inflammatory swelling of LNs. • We investigated the value of dual energy spectral CT in differentiating metastatic from non-metastatic lymph nodes in rectal cancer. Our study demonstrated that the quantitative normalized iodine concentration (nIC) could be useful for differentiating metastatic and non-metastatic lymph nodes. The combination of nIC in portal venous phase and conventional size criterion could improve the diagnostic accuracy, sensitivity, specificity, positive predictive value and negative predictive value of rectal cancer. - Abstract: Objectives: To investigate the value of dual energy spectral CT (DEsCT) imaging in differentiating metastatic from non-metastatic lymph nodes in rectal cancer. Methods: Fifty-five patients with rectal cancer underwent the arterial phase (AP) and portal venous phase (PP) contrast-enhanced DEsCT imaging. The virtual monochromatic images and iodine-based material decomposition images derived from DEsCT imaging were interpreted for lymph nodes (LNs) measurement. The short axis diameter and the normalized iodine concentration (nIC) of metastatic and non-metastatic LNs were measured. The two-sample t test was used to compare the short axis diameters and nIC values of metastatic and non-metastatic LNs. ROC analysis was performed to assess the diagnostic performance. Results: One hundred and fifty two LNs including 92 non-metastatic LNs and 60 metastatic LNs were matched using the radiological-pathological correlation. The mean short axis diameter of metastatic LNs was significantly larger than that of the non-metastatic LNs (7.28 ± 2.28 mm vs. 4.90 ± 1.64 mm, P < 0.001). The mean n

  15. The judgment of the Federal Constitutional Court on the phasing out of nuclear power. Consequences for phasing out of coal use; Das Urteil des Bundesverfassungsgerichts zum Atomausstieg. Konsequenzen fuer den Kohleausstieg

    Energy Technology Data Exchange (ETDEWEB)

    Ziehm, Cornelia

    2017-02-15

    The first nuclear phase out of 2002 has not been a subject of judicial review. The nuclear regulations at that time were based on negotiations between the then federal government and the operators. In the context of these negotiations, the operators themselves were committed to waive a judicial review. The Federal Constitutional Court now had first the opportunity to clarify the legal requirements for phase-out from a certain form of energy generation by means of the constitutional complaints lodged by the operators against the second nuclear phase-out amendment adopted by the 13th Atomic Energy Act. The nuclear phase-out of 2011 with fixed, staggered turn-off data for the individual nuclear power plants is, as a matter of principle, in accordance with the Karlsruher decision. The judgment of 6 December 2016 also merit relevance, especially with regard to the coal exit. [German] Der erste Atomausstieg von 2002 ist nicht gerichtlich ueberprueft worden. Die seinerzeitigen atomgesetzlichen Regelungen beruhten auf Verhandlungen zwischen der damaligen Bundesregierung und den Betreibern. Im Rahmen dieser Verhandlungen hatten sich die Betreiber ihrerseits verpflichtet, auf eine gerichtliche Ueberpruefung zu verzichten. Durch die von den Betreibern gegen den mit der 13. Atomgesetz-Novelle 2011 beschlossenen zweiten Atomausstieg eingelegten Verfassungsbeschwerden hatte das Bundesverfassungsgericht nunmehr erstmals die Gelegenheit, die rechtlichen Voraussetzungen eines Ausstiegs aus einer bestimmten Form der Energieerzeugung zu klaeren. Der Atomausstieg von 2011 mit fixen, gestaffelten Abschaltdaten fuer die einzelnen Atomkraftwerke ist nach der Karlsruher Entscheidung grundsaetzlich verfassungsgemaess. Dem Urteil vom 6. Dezember 2016 kommt auch und gerade im Hinblick auf den Kohleausstieg Relevanz dazu.

  16. La revolution des savants

    CERN Document Server

    Chavanne, A

    1989-01-01

    Premiere cassette : - 1666 : impact de la creation de l'Academie des Sciences par Colbert, trente ans apres le proces de Galile, et au moment des disparitions de Pascal, Descartes et Fermat. Elle dirigee par le hollandais Huyggens jusqu'a sa fuite de France au moment de la revocation de l'Edit de Nantes. - 1750 : l'Encyclopedie (ou "Dictionnaire raisonne des Sciences, des Arts et des Metiers") de Diderot et d'Alembert, soutenus par Malherbes, Buffon, Condorcet et Rousseau. - 1789 : Revolution francaise. - 8 aout 1793 : l'Assemblee, par une declaration de Marat, dissout l'Academie des Sciences. Celle-ci continue cependant ses travaux pour les poids et mesures jusqu'en 1795. - la Terreur : la condamnation a mort, pas au nom d'une "Revolution qui n'a pas besoin de savants" mais pour d'autres raisons, de trois grands hommes de science : Lavoisier, Bailly et Condorcet. - 1793-1794 : Au printemps 93, le Comite de Salut Publique s'inquiete du demi-million de soldats etrangers de toutes les pays frontaliers qui essai...

  17. Exclusive study of Ni+Ni and Ni+Au central collisions: phase coexistence and spinodal decomposition; Etude exclusive des collisions centrales Ni+Ni et Ni+Au: coexistence de phase et decomposition spinodale

    Energy Technology Data Exchange (ETDEWEB)

    Guiot, B

    2002-12-01

    The INDRA multidetector allowed us to study the Ni+Ni collisions at 32A MeV and the Ni+Au collisions at 52,4 MeV. Central collisions leading to 'quasi-fused' systems were isolated using multidimensional analysis techniques: the Discriminant Analysis and the Principal Component Analysis. Comparison with a statistical model shows that the selected events are compatible with thermodynamical equilibrium. The average thermal excitation energy is 5A MeV for both systems. Calculations of heat capacities show that the deexcitation of the hot sources are akin to a liquid-gas phase transition of nuclear matter. Indeed heat capacities exhibit a negative branch as expected for a phase transition of a finite system. The dynamics of this phase transition has been investigated by applying the charge correlation method. An enhanced production of events with equal-sized fragments has been evidenced for Ni+Au at 52A MeV. No signal was found for Ni+Ni at 32A MeV. Finally this method was improved by taking into account the total charge conservation. The signal is seen more clearly for Ni+Au at 52A MeV, but is ambiguous for Ni+Ni at 32A MeV. The path followed in the state diagram, or the involved time scales, seem to be different for these systems. (authors)

  18. Search for solar axions with the X-ray telescope of the CAST experiment (phase II); Suche nach solaren Axionen mit dem Roentgenteleskop des CAST-Experiments (Phase II)

    Energy Technology Data Exchange (ETDEWEB)

    Nordt, Annika

    2009-10-14

    The CAST (CERN Solar Axion Telescope) experiment is searching for solar axions by their conversion into photons inside a transverse magnetic field. So far, no solar axionsignal has been detected, but a new upper limit could be given (CAST Phase I). Since 2005, CAST entered in its second phase where it operates with a buffer gas ({sup 4}He) in the conversion region to extend the sensitivity of the experiment to higher axionmasses. For the first time it is possible to enter the theoretically favored axion massrange and to give an upper limit for this solar axion mass-range (>0.02 eV). This thesis is about the analysis of the X-ray telescope data Phase II with {sup 4}He inside the magnet. The result for the coupling constant of axions to photons is: g{sub {alpha}}{sub {gamma}}{sub {gamma}}<1.6-6.0 x 10{sup -10} GeV{sup -1} (95%C.L.) for m{sub a}=0.02-0.4 eV. (2) This result is better than any result that has been given before in this mass range for solar axions. (orig.)

  19. Extracting attosecond delays from spectrally overlapping interferograms

    Science.gov (United States)

    Jordan, Inga; Wörner, Hans Jakob

    2018-02-01

    Attosecond interferometry is becoming an increasingly popular technique for measuring the dynamics of photoionization in real time. Whereas early measurements focused on atomic systems with very simple photoelectron spectra, the technique is now being applied to more complex systems including isolated molecules and solids. The increase in complexity translates into an augmented spectral congestion, unavoidably resulting in spectral overlap in attosecond interferograms. Here, we discuss currently used methods for phase retrieval and introduce two new approaches for determining attosecond photoemission delays from spectrally overlapping photoelectron spectra. We show that the previously used technique, consisting in the spectral integration of the areas of interest, does in general not provide reliable results. Our methods resolve this problem, thereby opening the technique of attosecond interferometry to complex systems and fully exploiting its specific advantages in terms of spectral resolution compared to attosecond streaking.

  20. Feasibility of using of the second gradient theory for the direct numerical simulation of liquid-vapor flows with phase-change; Etude des potentialites de la theorie du second gradient pour la simulation numerique directe des ecoulements liquide-vapeur avec changement de phase

    Energy Technology Data Exchange (ETDEWEB)

    Jamet, D. [CEA Grenoble, 38 (France). Dept. de Thermohydraulique et de Physique]|[Ecole Centrale de Paris, 75 (France)

    1998-12-31

    One on the main difficulties encountered in the direct numerical simulation of two-phase flows in general and of liquid-vapor flows with phase-change in particular, is the interface tracking. The idea developed in this work consists in modeling a liquid-vapor interface as a volumetric zone across which physical properties vary continuously instead of a discontinuous surface. The second gradient theory allows to establish the evolution equations of the fluid in the whole system: bulk phases and interfaces. That means that the resolution of a unique system of partial differential equations is necessary to determine the whole two-phase flow, the interfaces and their evolution in time being a part of the solution of this unique system. We show in this work that it is possible to artificially enlarge an interface without changing its surface tension and the latent heat of vaporization. That means than it is possible to track all the interfaces of a liquid-vapor two-phase flow with phase-change on a mesh the size of which is imposed by the smallest Kolmogorov scale of the bulk phases for example. The artificial enlargement of an interfacial zone is obtained by modifying the thermodynamic behavior of the fluid within the binodal. We show that this modification does not change the dynamics of an interface. However, although the thickness of an interface and its surface tension vary with the mass and heat fluxes that go though it, the thermodynamic modification necessary to the artificial enlargement of an interface drastically increases these variations. Consequently, the artificial enlargement of an interface must be made carefully to avoid a too much important variation of its surface tension during dynamic situations. (author) 60 refs.

  1. Spectral evolution of galaxies: current views

    International Nuclear Information System (INIS)

    Bruzual, A.G.

    1985-01-01

    A summary of current views on the interpretation of the various evolutionary tests aimed at detecting spectral evolution in galaxies is presented. It is concluded that the evolution taking place in known galaxy samples is a slow process (perhaps consistent with no evolution at all), and that the early phases of rapid spectral evolution in early-type galaxies have not yet been detected. (author)

  2. First detection of lamella-gyroid-cylinder phase transition of neat polyethylene-poly(ethylene oxide) diblock copolymers on the basis of synchrotron WAXD/SAXS and infrared/Raman spectral measurements

    International Nuclear Information System (INIS)

    Weiyu, Cao; Tashiro, Kohji; Hanesaka, Makoto; Takeda, Shinichi; Masunaga, Hiroyasu; Sasaki, Sono; Takata, Masaki

    2009-01-01

    The phase transition behaviour of polyethylene-b-poly(ethylene oxide) (PE-b-PEO) diblock copolymer with relatively short chain lengths has been studied on the basis of temperature dependent infrared and Raman spectral measurements and synchrotron WAXD/SAXS simultaneous measurements, from which the concrete structural changes were deduced successfully from the various levels of molecular chain conformation, chain packing mode and higher-order structure. The higher-order structure has been found to transform between lamella, perforated lamella, gyroid, cylinder and sphere structures. The inner structural changes occurring in the polyethylene and poly(ethylene oxide) parts have been related with these morphological changes. The morphological transition from lamella to gyroid occurs with keeping the crystalline state of polyethylene parts. This apparently curious transition can be interpreted reasonably by assuming the thermally-activated chain motion in the crystal lattice, which may play an important role as a trigger to induce the morphological change from lamella to gyroid. This idea was supported by the measurement of half-width of Raman anti-symmetric CH 2 stretching band sensitive to the thermal mobility of alkyl chains.

  3. Oxidation and Reduction of Iron-Titanium Oxides in Chemical Looping Combustion: A Phase-Chemical Description Oxydation et réduction des minerais de fer-titane dans la combustion en boucle chimique

    Directory of Open Access Journals (Sweden)

    den Hoed P.

    2011-05-01

    Full Text Available Ilmenite (FeTiO3 is being explored as an oxygen carrier in chemical looping processes. Its reduction and oxidation are described by the system Fe-Fe2O3-TiO2-Ti2O3. The phase diagram at 1 000°C, presented here, offers a useful tool for predicting reactions and their products. We see that Fe2TiO5 (pseudobrookite and TiO2 (rutile form a stable phase assemblage following the oxidation of FeTiO3 (ilmenite in air. The subsequent reduction of Fe2TiO5 at oxygen partial pressures of 10-15.5atm stabilizes Fe1.02Ti0.98O3, a solid solution of ilmenite. Further reduction will produce metallic iron, which compromises the integrity of the oxygen carrier for chemical looping processes. We speculate that the reduction of Fe-Ti oxides in several practical instances does not reach completion (and equilibrium under the imposed atmospheres operating in fuel reactors. L’ilménite (FeTiO3 est considéré comme un transporteur d’oxygène potentiel pour les procédés en boucle chimique. Ses mécanismes de réduction et d’oxydation sont décrits à travers le système Fe-Fe2O3-TiO2-TiO3. Le diagramme de phase à 1 000°C, présenté ici, est un outil utile pour prédire les réactions et les produits. Nous constatons que Fe2TiO5 (pseudobrookite et TiO2 (rutile forment un assemblage de phase stable après oxydation de l’ilménite (FeTiO3 dans l’air. La réduction subséquente de Fe2TiO5 à la pression partielle de 10−15,5atm stabilise vers Fe1.02Ti0.98O3, une solution solide d’ilménite. Une réduction plus poussée va produire du fer métallique et compromettre l’intégrité du transporteur d’oxygène dans la boucle chimique. Il est probable que la réduction des oxydes Fe-Ti ne soit pas, en pratique, complète et n’atteigne pas l’équilibre dans les conditions rencontrées en opération dans les réacteurs de réduction.

  4. Contribution des radios communautaires a l'education des ...

    African Journals Online (AJOL)

    Contribution des radios communautaires a l'education des populations rurales pour un developpement durable au Benin: etude de cas. ... Journal de la Recherche Scientifique de l'Université de Lomé. Journal Home · ABOUT THIS JOURNAL ...

  5. La convergence des rôles respectifs des relationnistes et des journalistes influence-t-elle la perception qu'ils ont les uns des autres?

    DEFF Research Database (Denmark)

    Valentini, Chiara

    2017-01-01

    la convergence des rôles respectifs des praticiens des relations publiques et des journalistes a un effet favorable sur la perception qu’ils ont les uns des autres. L’effet est plus marqué chez les praticiens des relations publiques, car leur vision de la profession en journalisme correspond à celle...

  6. Promouvoir l'entrepreneuriat inclusif des jeunes et des femmes ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Le projet vise à analyser la contribution réelle et potentielle de l'entrepreneuriat inclusif au bien-être des jeunes et des femmes en Côte d'Ivoire, au Burkina Faso et au Kenya. Après un état des lieux de la pratique de l'entrepreneuriat inclusif dans chacun des pays ciblés, l'équipe de recherche étudiera son incidence sur ...

  7. Étude expérimentale de l'hydrodynamique des suspensions non ...

    African Journals Online (AJOL)

    Abstract. Nous avons mené des travaux de recherches sur l'hydrodynamique des suspensions dans le but de bien appréhender les problèmes liés à l'influence de la phase dispersée des écoulements chargés en sphères dures dans l'industrie agroalimentaire. Dans ce papier nous présentons les résultats de ces travaux.

  8. Indemnisation des dommages résultant de soins de santé. Phase V : impact budgétaire de la transposition du système français en Belgique

    OpenAIRE

    Yerna, Benoît-Laurent; Maréchal, Xavier; Denuit, Michel; Closon, Jean-Pierre; Vinck, Imgard

    2009-01-01

    L’objectif de la présente étude consiste, d’une part, à décrire le système français d’indemnisation des victimes de dommages médicaux et, d’autre part, à calculer l’impact budgétaire de la transposition d’un tel système en Belgique. Les spécificités du système qui sera introduit en Belgique n’étant pas connues au moment de l’étude, le coût a été calculé sur la base des modalités du système en vigueur en France. Les statistiques françaises de fréquences des différents types de dommages (infect...

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

    Science.gov (United States)

    Bendaoud, Adlane Larbi

    . Dans la partie theorique, un modele traitant les aspects thermique, hydrodynamique et massique a ete elabore. Sur la base de ce modele a ete ecrit un programme informatique en langage FORTRAN 6.6. Il est base sur la discretisation du serpentin en volumes de controle, est entierement automatise et peut traiter des echangeurs de chaleur avec des circuits de refrigerant complexes pouvant avoir des entrees et sorties multiples ainsi que des bifurcations. La presence simultanee des trois phases thermodynamiques du refrigerant (liquide sous refroidi, fluide sature, vapeur surchauffee) dans le serpentin est aussi prise en charge. Le modele a ete valide pour un fonctionnement avec et sans formation de givre en utilisant des donnees experimentales disponibles dans la litterature et celles obtenues sur le banc d'essai de CanmetENERGIE. Celui-ci a ete mis a jour pour les besoins de la presente recherche et pour cela, un systeme de surchauffe et d'injection de la vapeur d'eau dans une enceinte a tres basse temperature a ete dimensionne, fabrique et installe. Un dispositif de visualisation de la formation de givre, ainsi qu'un equipement de mesure de la temperature, de la pression et de l'humidite relative de l'air ont aussi ete ajoutes. Une fois le modele valide, des simulations numeriques sur le serpentin avec et sans formation de givre ont ete effectuees. Un premier cas de base a servi comme reference pour d'autres cas pour lesquels une etude parametrique sur la geometrie et le fonctionnement a ete menee. Il a ete montre par rapport au cas de base que : 1. la diminution de la densite des ailettes sur des rangees specifiques du serpentin donne une surface minimale (Amin) plus grande, retardant ainsi l'obstruction totale du serpentin par le givre et permet donc un temps de fonctionnement plus grand et une frequence de degivrage plus faible. 2. une bonne configuration de circuit de refrigerant augmente le temps de fonctionnement du serpentin de 200 % et delivre une puissance

  10. La fabrique des sciences des institutions aux pratiques

    CERN Document Server

    Benninghoff, Martin; Crettaz von Roten, Fabienne; Merz, Martina

    2006-01-01

    Aujourd'hui, les façons de produire, d'organiser, d'évaluer et d'utiliser les savoirs sont en profond débat. De plus en plus, l'Etat, la société civile et l'économie tentent d'influencer les activités des universités et des laboratoires de recherche. Ces développements mettent à l'épreuve tout à la fois les fondements des systèmes d'enseignement supérieur et de recherche, l'autonomie des institutions scientifiques, la définition des frontières des savoirs et l'acceptation des sciences. Dans des contextes suisses et européens, cet ouvrage s'intéresse aux manières dont les sciences et les technologies sont fabriquées, en analysant leurs institutions et les pratiques. A partir d'une approche relationnelle, les sciences et les technologies sont conçues comme des phénomènes profondément sociaux, culturels et politiques. Une telle démarche déstabilise les visions parfois idéalisées et stéréotypées de la construction des savoirs. Des études de cas détaillées décrivent des phénomè...

  11. Effets des extraits vegetaux sur la dynamique de populations des ...

    African Journals Online (AJOL)

    La présente étude se propose de trouver une alternative de l'utilisation des pesticides chimiques en testant l'effet insecticide des extraits aqueux des feuilles de Hyptis suaveolens, graines de Ricinus communis et de Azadirachta indica contre les ravageurs du niébé en conditions de champ en utilisant le cyperméthrine ...

  12. {gamma} alumina- and HY zeolite-supported molybdenum catalysts: characterisation of the oxidic and sulfided phases; Catalyseurs a base de molybdene supporte sur alumine {gamma} et zeolithe HY: caracterisation des phases oxydes et sulfures

    Energy Technology Data Exchange (ETDEWEB)

    Plazenet, G

    2001-10-01

    Oxidic precursors of hydro-treatment catalysts (Co)Mo/alumina or zeolite were characterised by Raman spectroscopy, NMR and EXAFS at the Mo and Co K-edges. The formation of an Anderson-type alumino-molybdate compound upon impregnation of the support with an ammonium hepta-molybdate solution was confirmed for alumina, and also observed for the HY zeolitic support, with consumption of the amorphous alumina of the zeolite. In absence of the latter, ammonium hepta-molybdate precipitates. The species are conserved upon drying; upon calcination, the alumino-molybdate evolves into a surface aluminium molybdate type phase, whereas the hepta-molybdate transforms into MoO{sub 3}. The species formed upon impregnation are located in the inter-granular porosity whereas MoO{sub 3} vapor-condensation leads to formation of dimers located inside the zeolitic structure. The study of the cobalt-promoted precursors showed that the evolution of the molybdenum is the same in the case of co-impregnation preparation. Impregnation with cobalt-molybdate prevents the formation of the alumino-molybdate anion and thus enables the preservation of the Mo-Co interaction but, whatever the precursor, the leveling effect of the calcination-re-hydration steps was demonstrated. An EXAFS study at different sulfur coverages of the MoS{sub 2} platelets in the alumina-supported sulfided catalysts showed the limitations of EXAFS for size determination of MoS{sub 2} crystallites, a parameter that can be reached by AWAXS, which also conveys information about sheet-stacking. The EXAFS study of sulfided (Co)Mo/HY systems revealed incomplete sulfidation of the samples and the very high dispersion of the active phase. The absence of an observable Mo-Co interaction whatever the preparation of the promoted catalysts is consistent with the absence of promoting effect in toluene hydrogenation. (author)

  13. New graphite/salt materials for high temperature energy storage. Phase change properties study; Nouveaux materiaux graphite/sel pour le stockage d'energie a haute temperature. Etude des proprietes de changement de phase

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, J

    2007-07-15

    This work is a contribution to the study of new graphite/salt composites dedicated to high temperature energy storage ({>=}200 C). The aim is to analyse and to understand the influence of both graphite and composite microstructure on the phase change properties of salts. This PhD is carried out within the framework of two projects: DISTOR (European) and HTPSTOCK (French). The major contributions of this work are threefold: 1) An important database (solid-liquid phase change properties) is provided from the DSC analysis of six salts and the corresponding composites. 2) Rigorous modeling of salts melting in confined media in several geometries are proposed to understand why, during the first melting of the compression elaborated composites, problems of salt leakage are observed. These models show that the materials morphology is responsible for these phenomena: the graphite matrix restrains the volume expansion due to salt melting: salt melts under pressure, which leads to a melting on a large temperature range and to a loss of energy density. Sensitivity analysis of parameters (geometric and physic) shows that matrix rigidity modulus is the parameter on which it is necessary to act during the composites elaboration to blur this phenomenon. 3) Finally, this work proposes a thermodynamic formulation of both surface/interface phenomena and the presence of dissolved impurities being able to explain a melting point lowering. It seems that the melting point lowering observed ({approx} 5 C) are mainly due to the presence of dissolved impurities (brought by graphite) in the liquid, along with an additional Gibbs-Thomson effect ({approx} 1 C, related to the size of the clusters crystals). (author)

  14. Modeling of Multiphase with Respect to Low Interfacial Tension by Pseudo-Two-Phase Relative Permeability Functions Modélisation d'un écoulement polyphasique à faible tension interfaciale par des fonctions pseudo-biphasiques de perméabilité relative

    Directory of Open Access Journals (Sweden)

    Pusch G.

    2006-11-01

    Full Text Available A new 2-parameter desaturation function is introduced which offers a broader range of applicability to reservoir rock. Based on this function two-phase relative permeabilities are derived for oil phase and microemulsion flow. These functions are used to match a laboratory experiment by using surfactant flooding for a single surfactant system. Les auteurs présentent une nouvelle fonction de désaturation à deux paramètres qui offre une plus large gamme de possibilités d'application aux roches réservoir. On tire de cette fonction des perméabilités relatives biphasiques pour l'écoulement de la phase pétrole et d'une microémulsion. Ces fonctions sont utilisées pour reproduire une expérience de laboratoire avec injection de surfactant pour un seul système surfactant.

  15. Heavy water reactors physics; Physique des reacteurs a eau lourde

    Energy Technology Data Exchange (ETDEWEB)

    Girard, Y; Lourme, P; Naudet, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    An important research programme on heavy water reactor physics has been carried out in France for quite a few years. The decision to build the EL 4 prototype and so to choose the heavy water gas cooled type has renewed the interest in this programme and at the same time given to it a more specific orientation A summary of the results gained in this field is presented in this paper. In the first part are described the experimental investigations, most of them were carried out in the criticality facility AQUILON II. The experiments are grouped in four parts - Systematic studies of lattices Buckling measurements. - Specific studies of gas-cooled lattices. - Fine structure, spectral indices measurements etc... - Measurements on lattices or samples containing Uranium of various enrichment or Plutonium. The second part is devoted to a summary of the theoretical studies. The whole results have allowed an improvement of the calculation methods, have led to a better understanding of the neutron balance in lattices, and have permitted the establishment of a set of formula to predict not only the clean fuel conditions but also the evolution of the nuclear properties with irradiation. Some specific studies on power reactor are quoted. (authors) [French] Un important programme d'etudes sur la physique des reacteurs a eau lourde est mene en France depuis assez longtemps. La decision de construire le prototype EL 4 et de s'engager ainsi dans la filiere des reacteurs a eau lourde refroidis par gaz a redonne un nouvel interet a ce programme et l'a en meme temps oriente dans une direction plus particuliere. La presente communication, rassemble les resultats des etudes faites dans ce domaine depuis la derniere conference de Geneve. Dans la premiere partie on decrit les etudes experimentales dont la plupart ont ete effectuees dans la pile d'experiences critiques Aquilon II. Les experiences sont groupees en quatre ensembles: etude systematique de reseaux (mesures de laplaciens) etudes

  16. Charte du Conseil des Gouverneurs

    International Development Research Centre (IDRC) Digital Library (Canada)

    Office 2004 Test Drive User

    7. favoriser des communications ouvertes et franches entre le personnel, la direction ..... de dresser le procès-verbal des réunions du Conseil et de ses comités et de veiller à ce ... et des résultats qu'il obtient, et non de sa gestion quotidienne.

  17. Study of the thorium phosphate-diphosphate (TPD) dissolution: kinetic aspect - thermodynamic aspect: analysis of the neo-formed phases; Etude de la dissolution du phosphate diphosphate de thorium: - aspect cinetique - aspect thermodynamique: analyse des phases neoformees

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, A.Ch

    2000-10-06

    The aim of this work is to study the aqueous corrosion of the thorium phosphate-diphosphate (TPD), of the formula Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}, in the framework of the actinides immobilization. In order to complete the anterior studies concerning solid solutions where thorium is substituted by a tetravalent ion (uranium (IV) or plutonium (IV)) in the TPD structure, compounds of thorium and neptunium phosphate-diphosphate, of formula Th{sub 4-x}Np{sub x}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}, have been prepared. Furthermore, a new chemical way of synthesis has been investigated in order to sinter solids solution of thorium and uranium phosphate-diphosphate (TUPD) in good conditions. The TPD dissolution study showed two principals steps. The first one corresponds to the control of element concentration by the material dissolution whereas the second corresponds to the formation of secondary precipitates for which thermodynamic equilibrium controls the concentration of the species in solution. Leaching tests have been performed varying several independent parameters in order to determine the TPD dissolution rate. The partial orders related to the protons or to the hydroxide ions have been found between 0.35 and 0.45 whereas the apparent dissolution rate constants are in the range 1.10{sup -5} for 9.10{sup -5} g.m{sup -2}.j{sup -1} for acidic and basic media. The neo-formed phases have been characterized after the dissolution of TPD and TUPD. We found that the TPD leaching in acidic medium leads to the formation of the crystallized thorium phosphate-hydrogen-phosphate (TPHP), of formula Th{sub 2}(PO{sub 4}){sub 2}(HPO{sub 4}), x H{sub 2}O, whereas the TUPD dissolution leads to the TPHP and an other compound, of formula (UO{sub 2}){sub 3}(PO{sub 4}){sub 2}, 5 H{sub 2}O. We calculated its solubility product which is in good agreement with those found in the literature. The phases formed during the leaching of solids containing plutonium; americium or curium (Th

  18. Introduction to spectral theory

    CERN Document Server

    Levitan, B M

    1975-01-01

    This monograph is devoted to the spectral theory of the Sturm- Liouville operator and to the spectral theory of the Dirac system. In addition, some results are given for nth order ordinary differential operators. Those parts of this book which concern nth order operators can serve as simply an introduction to this domain, which at the present time has already had time to become very broad. For the convenience of the reader who is not familar with abstract spectral theory, the authors have inserted a chapter (Chapter 13) in which they discuss this theory, concisely and in the main without proofs, and indicate various connections with the spectral theory of differential operators.

  19. Le statut vitaminique des individus et des populations…

    Directory of Open Access Journals (Sweden)

    Icart Jean-Claude

    2000-05-01

    Full Text Available Comme le souligne un récent rapport du Haut comité de santé publique, le statut vitaminique des individus et des populations demeure une question d’actualité. Si les études ne révèlent plus de signes évocateurs de carence, au plus des problèmes de déficiences pour certains groupes à risque, des interrogations, demeurent malgré le contexte d’abondance, concernant la couverture des besoins, laquelle pourrait s’avérer inférieure aux valeurs considérées comme satisfaisantes.

  20. Les lueurs des sables

    CERN Multimedia

    Les lueurs des sables

    2013-01-01

    Two CERN ladies are getting ready for the “Trophée Roses des Sables” rally adventure: Julie and Laetitia are finalizing the last details before setting off on Monday 7th October 2013. Julie from EN-MEF group and Laetitia from DGS-SEE group, met at the CERN Rugby club. This year, they are participating in the 100 % female rally which will take place in Morocco from 10 to 20 October. They will be carrying along 100 kg of humanitarian donation for children such as some clothes, books and medical material. Do not hesitate to show your support at their farewell party to be held on Monday 7 October, from 4 to 6 pm in front of the St Genis-Pouilly Mairie (city Hall). Follow their exciting adventure on the blog leslueursdessables.trophee-roses-des-sables.org and on their association’s Facebook page Les Lueurs des Sables.

  1. Liste des auteurs

    OpenAIRE

    2016-01-01

    Madeleine Akrich      Ecole des Mines – Centre de Sociologie de l’innovation – Paris Noël Barbe      Association comtoise des Arts et Traditions populaires – Besançon Lucien Bernot      Ecole des hautes études en sciences sociales (EHESS) – Paris Anni Borzeix      Centre national de la recherche scientifique (CNRS) –     Groupement d’intérêt public (GIP) « Mutations industrielles » – Paris François Boudarias      Laboratoire d’Anthropologie et de sociologie de Tours (LAST) Dominique Boullier ...

  2. 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)

  3. Towards a physical interpretation of third phase formation in liquid-liquid extraction. Application to the Diamex process for the treatment of high radioactive nuclear wastes; Vers une interpretation physique des phenomenes de troisieme phase en extraction liquide-liquide. Application au procede Diamex de traitement des effluents radioactifs de haute activite

    Energy Technology Data Exchange (ETDEWEB)

    Verdier-Erlinger, C

    1998-07-24

    Using SAXS, conductivity and phase behaviour determination we show that concentrated solutions of extractants are organised in reverse oligomeric aggregates which have many features in common with reverse micelles. The aggregation numbers of these reverse globular aggregates as well as their interaction potential are determined experimentally. The sticky sphere interaction is responsible for the de-mixing on the oil phase when in equilibrium with excess oil. Prediction of conductivity as well as formation condition for the third phase is possible using standard liquid theory applied to the reverse micelles. The attractive interaction, modeled with the sticky sphere model proposed by Baxter, is the balance of steric stabilisation introduced by the hydrophobic tails of the extracting molecule and the Van der Waals forces between the highly polarizable water core of the reverse molecule concentration, number of carbon atoms of aliphatic solvents, as well as proton and Neodymium cation concentration. It is shown that van der Waals interactions with a Hamaker constant of 2.5 kT explains the behaviour of DMDBTDMA in dodecane. (author) 184 refs.

  4. Évaluation des pratiques agricoles des légumes feuilles : le cas des ...

    African Journals Online (AJOL)

    Face à ce constat, le défi de la recherche serait la détermination du niveau actuel de contamination des légumes feuilles et des eaux du barrage et celui de l'État serait l'initiation de programmes de sensibilisation des producteurs par rapport à une gestion plus rigoureuse des pesticides. Mots-clés : pratiques paysannes, ...

  5. Avoir un impact à grande échelle au moyen des services de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Avoir un impact à grande échelle au moyen des services de vulgarisation reposant sur les TIC au Ghana (FCRSAI, phase II). En Afrique, les services de vulgarisation agricoles peuvent contribuer à développer les marchés et à renforcer la sécurité alimentaire des petits exploitants agricoles. La vulgarisation agricole se sert ...

  6. Variabilité de la composition chimique de l'huile essentielle des ...

    African Journals Online (AJOL)

    SARAH

    30 avr. 2015 ... elles sont séchées à l'abri de la lumière à température ... moyen des techniques de Chromatographie en phase ..... Figure 2: ACP - Carte des variables suivant les composantes PC1 et .... Guide pratique / GRD PAGE-PACA,.

  7. Application des TIC à l'atténuation des effets des catastrophes dans ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    L'Amérique centrale est souvent aux prises avec des inondations et des ... (SIG) et de traitement des images, afin de cartographier les dangers et de modéliser les ... de l'Institut d'étude du développement international de l'Université McGill.

  8. On Longitudinal Spectral Coherence

    DEFF Research Database (Denmark)

    Kristensen, Leif

    1979-01-01

    It is demonstrated that the longitudinal spectral coherence differs significantly from the transversal spectral coherence in its dependence on displacement and frequency. An expression for the longitudinal coherence is derived and it is shown how the scale of turbulence, the displacement between ...... observation sites and the turbulence intensity influence the results. The limitations of the theory are discussed....

  9. Optimisation des codes LDPC irréguliers et algorithmes de décodage des codes LDPC q-aires

    OpenAIRE

    Cances , Jean-Pierre

    2013-01-01

    Cette note technique rappelle les principes d'optimisation pour obtenir les profils de codes LDPC irréguliers performants et rappelle les principes des algorithmes de décodage utilizes pour les codes LDPC q-aires à grande efficacité spectrale.

  10. REPRISE DES COURS - Yoga

    CERN Multimedia

    Club de Yoga

    2015-01-01

    REPRISE DES COURS – Venez nombreux ! Yoga, Sophrologie, Tai Chi La liste des cours pour le semestre allant du 1er septembre 2015 au 31 janvier 2016 est disponible sur notre site web : http://club-yoga.web.cern.ch Lieu Les cours ont lieu dans la salle des clubs, à l’entresol du restaurant No 2, Bât. 504 (dans la salle no 3 pour la Sophrologie). Prix des cours Le prix pour le semestre (environ 18 leçons) est fixé à 220 CHF plus 10 CHF d’adhésion annuelle au Club. Couple : 200 CHF par personne. 2 cours par semaine : 400 CHF. Inscriptions Les inscriptions aux cours seront prises directement auprès du professeur, lors de la 1ère séance. Avant de s’inscrire pour le semestre, il est possible d’essayer une séance gratuitement. Informations : http://club-yoga.web.cern.ch ----------------------------------------- cern.ch/club-yoga/

  11. Praxis des Klebens

    CERN Document Server

    Theuerkauff, Petra

    1989-01-01

    Bei diesem Buch handelt es sich um einen Leitfaden fur Klebepraktiker. Es werden die verschiedenen Einzelschritte beim kleben beschrieben, als auch die vorbereitenden Massnahmen und anschliessenden Prufverfahren auf Festigkeit behandelt. Das Buch sollte an keinem Arbeitsplatz fehlen, wo man sich mit Problemen der Fugetechnik des Klebens beschaftigt.

  12. Dimensions des stabulations 2018

    OpenAIRE

    Früh, Barbara; Maurer, Veronika; Schneider, Claudia; Schürmann, Stefan; Spengler Neff, Anet; Werne, Steffen

    2018-01-01

    Les «Dimensions des stabulations» contiennent toutes les dimensions pour les stabulations et les parcours pour la production animale en agriculture biologique. Cette liste sert d’instrument de planification pour les éleveurs, d’outil de travail pour la vulgarisation et d’ouvrage de référence pour le contrôle bio.

  13. Direction des Publications

    African Journals Online (AJOL)

    Synthese

    économique des services rendus par les écosystèmes marins. La richesse ... croissance plus rapide que la moyenne de l‟économie ...... services and natural capital. Nature. 387, 253-260. .... d‟interactions où l‟humain est partie prenante. In.

  14. La physique des infinis

    CERN Document Server

    Bernardeau, Francis; Laplace, Sandrine; Spiro, Michel

    2013-01-01

    Écrire l'histoire de l'Univers, tel est l'objectif commun des physiciens des particules et des astrophysiciens. Pour y parvenir, deux approches s'épaulent : la voie de l'infiniment petit, que l'on emprunte via de gigantesques accélérateurs de particules, et celle de l'infiniment grand, dont le laboratoire est l'Univers. Un Univers qui est bien loin d'avoir livré tous ses secrets. On connaît à peine 4,8 % de la matière qui le constitue, le reste étant composé de matière noire (25,8 %) et d'énergie noire (69,4 %), toutes deux de nature inconnue. Et si la récente découverte du boson de Higgs valide le Modèle standard de la physique des particules, celui-ci est toujours incomplet et doit être étendu à ou dépassé. Est-on arrivé au bout du jeu de poupées russes de la matière ? Quelles sont les particules manquantes ? Faut-il revoir les lois fondamentales ? Quels instruments faut-il mettre en œuvre pour accéder à cette « nouvelle physique » ? Comment parler de Super Big Science aux citoye...

  15. Effets des sels sur la réflectance et télédétection des sols salés

    OpenAIRE

    Mougenot, Bernard

    1993-01-01

    La présence de sels dans les sols et les nappes modifie les états de surface. La télédétection facilite leur identification et améliore la cartographie des sols salés. On distingue des effets directs sur la réflectance avec la présence de sels en surface (croûtes ou efflorescences salines), et des effets indirects sur la structure (pseudosables), la végétation (stress salin, végétation spécifique) ou l'absence de végétation dans les cas extrêmes. Les caractéristiques spectrales des sels du vi...

  16. Counter-IED PPE Horizon 0, Phase 1 Human Factors Trial: Performance Evaluation of Soft Armour Personal Protective Equipment (Essai Ergonomique du Projet Horizon 0 d’EPI a l’Epreuve des IED, Phase 1: Evaluation du Rendement d’un Equipement de Protection Individual en Materiel Souple)

    Science.gov (United States)

    2008-03-31

    du rendement et d’évaluations produites par des observateurs en ergonomie . Les conditions d’essai ont eu recours au concept de protection que...du rendement et à des évaluations faites par des observateurs en ergonomie . Après avoir mise à l’épreuve toutes les conditions de protection souple...observateurs en ergonomie . Les conditions d’essai ont eu recours au concept de protection que constitue le Système de gilet pare balles tactique modulaire

  17. Injectabilite des coulis de ciment dans des milieux fissures

    Science.gov (United States)

    Mnif, Thameur

    Le travail presente ici est un bilan du travaux de recherche effectues sur l'injectabilite des coulis de ciment dans lu milieux fissures. Un certain nombre de coulis a base de ciment Portland et microfin ont ete selectionnes afin de caracteriser leur capacite a penetrer des milieux fissures. Une partie des essais a ete menee en laboratoire. L'etude rheologique des differents melanges a permis de tester l'influence de l'ajout de superplastifiant et/ou de fumee de silice sur la distribution granulometrique des coulis et par consequent sur leur capacite a injecter des colonnes de sable simulant un milieu fissure donne. La classe granulometrique d'un coulis, sa stabilite et sa fluidite sont apparus comme les trois facteurs principaux pour la reussite d'une injection. Un facteur de finesse a ete defini au cours de cette etude: base sur la classe granulometrique du ciment et sa stabilite, il peut entrer dans la formulation theorique du debit d'injection avant application sur chantier. La deuxieme et derniere partie de l'etude presente les resultats de deux projets de recherche sur l'injection realises sur chantier. L'injection de dalles de beton fissurees a permis le suivi de l'evolution des pressions avec la distance au point d'injection. L'injection de murs de maconnerie a caractere historique a montre l'importance de la definition de criteres de performance des coulis a utiliser pour traiter un milieu donne et pour un objectif donne. Plusieurs melanges peuvent ainsi etre predefinis et mis a disposition sur le chantier. La complementarite des ciments traditionnels et des ciments microfins devient alors un atout important. Le choix d'utilisation de ces melanges est fonction du terrain rencontre. En conclusion, cette recherche etablit une methodologie pour la selection des coulis a base de ciment et des pressions d'injection en fonction de l'ouverture des fissures ou joints de construction.

  18. Soutien organisationnel de la phase 2 de l'Initiative Think tank ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    À propos de l'Institute of Statistical, Social and Economic Research ... son rendement organisationnel et son interaction avec la sphère des politiques. ... moyen des services de vulgarisation reposant sur les TIC au Ghana (FCRSAI, phase II).

  19. Screening phytochimique et identification spectroscopique des ...

    African Journals Online (AJOL)

    Origin

    plante, effectuée pour la première fois, a révélé la présence des alcaloïdes, des flavonoïdes, des tanins catéchiques, des terpènes, des coumarines et des composés cyanogénétiques. Quant aux saponines et les quinones libres, ils sont présents chez les fleurs et absents chez les feuilles. La caractérisation des molécules.

  20. Efficacité des néonicotinoïdes et des pyréthrinoïdes utilisés contre le ...

    African Journals Online (AJOL)

    Efficacité des néonicotinoïdes et des pyréthrinoïdes utilisés contre le foreur des tiges du cacaoyer ( Eulophonotus myrmeleon Felder : Lepidoptera, Cossidae). Implications dans la stratégie de protection de la cacaoculture en Côte d'Ivoire.

  1. Spectral properties of nuclear matter

    International Nuclear Information System (INIS)

    Bozek, P

    2006-01-01

    We review self-consistent spectral methods for nuclear matter calculations. The in-medium T-matrix approach is conserving and thermodynamically consistent. It gives both the global and the single-particle properties the system. The T-matrix approximation allows to address the pairing phenomenon in cold nuclear matter. A generalization of nuclear matter calculations to the super.uid phase is discussed and numerical results are presented for this case. The linear response of a correlated system going beyond the Hartree-Fock+ Random-Phase-Approximation (RPA) scheme is studied. The polarization is obtained by solving a consistent Bethe-Salpeter (BS) equation for the coupling of dressed nucleons to an external field. We find that multipair contributions are important for the spin(isospin) response when the interaction is spin(isospin) dependent

  2. Estimation of spectral kurtosis

    Science.gov (United States)

    Sutawanir

    2017-03-01

    Rolling bearings are the most important elements in rotating machinery. Bearing frequently fall out of service for various reasons: heavy loads, unsuitable lubrications, ineffective sealing. Bearing faults may cause a decrease in performance. Analysis of bearing vibration signals has attracted attention in the field of monitoring and fault diagnosis. Bearing vibration signals give rich information for early detection of bearing failures. Spectral kurtosis, SK, is a parameter in frequency domain indicating how the impulsiveness of a signal varies with frequency. Faults in rolling bearings give rise to a series of short impulse responses as the rolling elements strike faults, SK potentially useful for determining frequency bands dominated by bearing fault signals. SK can provide a measure of the distance of the analyzed bearings from a healthy one. SK provides additional information given by the power spectral density (psd). This paper aims to explore the estimation of spectral kurtosis using short time Fourier transform known as spectrogram. The estimation of SK is similar to the estimation of psd. The estimation falls in model-free estimation and plug-in estimator. Some numerical studies using simulations are discussed to support the methodology. Spectral kurtosis of some stationary signals are analytically obtained and used in simulation study. Kurtosis of time domain has been a popular tool for detecting non-normality. Spectral kurtosis is an extension of kurtosis in frequency domain. The relationship between time domain and frequency domain analysis is establish through power spectrum-autocovariance Fourier transform. Fourier transform is the main tool for estimation in frequency domain. The power spectral density is estimated through periodogram. In this paper, the short time Fourier transform of the spectral kurtosis is reviewed, a bearing fault (inner ring and outer ring) is simulated. The bearing response, power spectrum, and spectral kurtosis are plotted to

  3. Spectrally accurate contour dynamics

    International Nuclear Information System (INIS)

    Van Buskirk, R.D.; Marcus, P.S.

    1994-01-01

    We present an exponentially accurate boundary integral method for calculation the equilibria and dynamics of piece-wise constant distributions of potential vorticity. The method represents contours of potential vorticity as a spectral sum and solves the Biot-Savart equation for the velocity by spectrally evaluating a desingularized contour integral. We use the technique in both an initial-value code and a newton continuation method. Our methods are tested by comparing the numerical solutions with known analytic results, and it is shown that for the same amount of computational work our spectral methods are more accurate than other contour dynamics methods currently in use

  4. Spectral radius of graphs

    CERN Document Server

    Stevanovic, Dragan

    2015-01-01

    Spectral Radius of Graphs provides a thorough overview of important results on the spectral radius of adjacency matrix of graphs that have appeared in the literature in the preceding ten years, most of them with proofs, and including some previously unpublished results of the author. The primer begins with a brief classical review, in order to provide the reader with a foundation for the subsequent chapters. Topics covered include spectral decomposition, the Perron-Frobenius theorem, the Rayleigh quotient, the Weyl inequalities, and the Interlacing theorem. From this introduction, the

  5. Spectral Purity Enhancement via Polyphase Multipath Circuits

    NARCIS (Netherlands)

    Mensink, E.; Klumperink, Eric A.M.; Nauta, Bram

    2004-01-01

    The central question of this paper is: can we enhance the spectral purity of nonlinear circuits by using polyphase multipath circuits? The basic idea behind polyphase multipath circuits is to split the nonlinear circuits into two or more paths and exploit phase differences between these paths to

  6. Finite size scaling and spectral density studies

    International Nuclear Information System (INIS)

    Berg, B.A.

    1991-01-01

    Finite size scaling (FSS) and spectral density (SD) studies are reported for the deconfining phase transition. This talk concentrates on Monte Carlo (MC) results for pure SU(3) gauge theory, obtained in collaboration with Alves and Sanielevici, but the methods are expected to be useful for full QCD as well. (orig.)

  7. La gestion des résultats des entreprises innovantes

    OpenAIRE

    Dumas, Guillaume

    2014-01-01

    Cette thèse s’intéresse à la gestion des résultats dans le cadre des entreprises innovantes. Elle est constituée de trois articles. Dans le premier, il s’agit d’examiner si les résultats des entreprises innovantes sont gérés et si le stade de développement des innovations influence cette gestion des résultats. Il apparaît que les résultats des entreprises innovantes sont gérés à la hausse. Cette gestion ne semble intervenir qu’au cours de l’activité d’innovation (c’est-à-dire lorsque les entr...

  8. Product analyses and kinetic studies on gas phase oxidation of the fuel additive ethyl tert-butyl ether and its products; Produktanalysen und Kinetikuntersuchungen der Gasphasenoxidation des Kraftstoffadditivs Ethyl-tert-butylether und seiner Produkte

    Energy Technology Data Exchange (ETDEWEB)

    Becker, K H; Thuener, L

    1997-04-01

    The widespread use of the additive ETBE in gasoline leads to an increased release of this compound into the atmosphere via evaporation or exhaust fumes. In order to determine the influence of this additive on trace gas cycles it is first necessary to carry out studies on the degradation mechanisms and pertinent kinetic properties of this substance. The aim of the present study was to examine the degradation mechanisms of the fuel additive t-butyl ethyl ether under atmospheric conditions. The reactions of the main degradation products (t-butyl formiate and t-butyl acetate, together ca. 80%) were also studied in order to obtain as complete a picture of the degradation paths as possible. This was to permit an assessment of the influence of ETBE and its products on tropospheric trace gas cycles and ozone formation. [Deutsch] Bei haeufigem Zusatz von ETBE in Benzin wird diese Verbindung durch Verdampfung oder als Abgas verstaerkt in die Atmosphaere abgegeben. Um den Einfluss des Additivs auf die Spurengas-Kreislaeufe zu bestimmen, sind daher Untersuchungen noetig, um die Abbau-Mechanismen und die zugehoerigen kinetischen Daten zu ermitteln. Das Ziel dieser Arbeit ist die Untersuchung der Abbaumechanismen des Kraftstoffadditivs t-Butylethylether unter atmosphaerischen Bedingungen. Fuer eine moeglichst vollstaendige Analyse des Abbauweges werden auch die Reaktionen der Hauptabbauprodukte (t-Butylformiat und t-Butylacetat, zusammen etwa 80%) untersucht. Dadurch soll der Einfluss auf troposphaerische Spurengas-Kreislaeufe und auf die Ozonbildung von ETBE und seinen Produkten abgeschaetzt werden. (orig./SR)

  9. Heat supply concept for trade. Vol. 3. Environmentally friendly and energy-saving heat supply for public institutions by private operator models (phase 1). Final report. Vol. 1; Waermelieferungskonzept des Handwerks. Bd. 3. Umweltfreundliche und energiesparende Waermeversorgung oeffentlicher Einrichtungen durch private Betreibermodelle (Phase 1). Abschlussbericht. Berichtsband 1

    Energy Technology Data Exchange (ETDEWEB)

    Hacker, J [ed.; Biermann, J; Koehler, U; Locke, R; Meyer, K

    1993-12-31

    Volume 1 of the report indicates two goals: (1): Investigation of the boundary conditions for heat supply models, using the example of the states of Berlin (West) and Niedersachsen. (2): Investigation of the available potential in Berlin (West). (HW) [Deutsch] Der Berichtsband 1 weist 2 Teilziele auf: Teilziel 1: Untersuchung der Rahmenbedingungen fuer Waermelieferungsmodelle am Beispiel des Stadtstaates Berlin (West) und des Flaechenstaates Niedersachsen. Teilziel 2: Potentialermittlung in Berlin (West). (HW)

  10. Spectral unmixing: estimating partial abundances

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2009-01-01

    Full Text Available techniques is complicated when considering very similar spectral signatures. Iron-bearing oxide/hydroxide/sulfate minerals have similar spectral signatures. The study focuses on how could estimates of abundances of spectrally similar iron-bearing oxide...

  11. Des dispositions responsables à prendre pour la protection des ...

    African Journals Online (AJOL)

    En considérant l'effet néfaste des maladies, des parasites, du changement climatique et d'autres facteurs environnementaux (les OGM par exemple) sur la survie des abeilles, la baisse de leurs populations dans certaines parties du monde ne saurait être attribuée aux seules pesticides. En plus, l'impact de ces derniers sur ...

  12. Aspects des Onychomycoses chez des patients camerounais de ...

    African Journals Online (AJOL)

    ... biologiques et évolutifs des onychomycoses chez des patients camerounais. Méthode : Il s'agit d'une étude rétrospective et descriptive menée de mars 2011 à mars 2014 dans l'unité de dermatologie de l'hôpital général de Douala (HGD), incluant des patients chez lesquels le diagnostic d'onychomycose avait été posé.

  13. Bidirectional soliton spectral tunneling effects in the regime of optical event horizon

    DEFF Research Database (Denmark)

    Gu, Jie; Guo, Hairun; Wang, Shaofei

    2015-01-01

    We study the cross-phase-modulation-induced soliton spectral shifting in the regime of the optical event horizon. The perturbed soliton to either red-shifting or blue-shifting is controllable, which could evoke bidirectional soliton spectral tunneling effects.......We study the cross-phase-modulation-induced soliton spectral shifting in the regime of the optical event horizon. The perturbed soliton to either red-shifting or blue-shifting is controllable, which could evoke bidirectional soliton spectral tunneling effects....

  14. Rectangular spectral collocation

    KAUST Repository

    Driscoll, Tobin A.; Hale, Nicholas

    2015-01-01

    Boundary conditions in spectral collocation methods are typically imposed by removing some rows of the discretized differential operator and replacing them with others that enforce the required conditions at the boundary. A new approach based upon

  15. Vowel Inherent Spectral Change

    CERN Document Server

    Assmann, Peter

    2013-01-01

    It has been traditional in phonetic research to characterize monophthongs using a set of static formant frequencies, i.e., formant frequencies taken from a single time-point in the vowel or averaged over the time-course of the vowel. However, over the last twenty years a growing body of research has demonstrated that, at least for a number of dialects of North American English, vowels which are traditionally described as monophthongs often have substantial spectral change. Vowel Inherent Spectral Change has been observed in speakers’ productions, and has also been found to have a substantial effect on listeners’ perception. In terms of acoustics, the traditional categorical distinction between monophthongs and diphthongs can be replaced by a gradient description of dynamic spectral patterns. This book includes chapters addressing various aspects of vowel inherent spectral change (VISC), including theoretical and experimental studies of the perceptually relevant aspects of VISC, the relationship between ar...

  16. Usages des TIC et socialisation professionnelle des enseignants-chercheurs

    OpenAIRE

    Lavielle-Gutnik, Nathalie; Massou, Luc

    2013-01-01

    En prenant appui sur une nouvelle analyse des données recueillies dans l’enquête Tec-Meus (2008-2011, MSH Lorraine) sur la place accordée par des enseignants-chercheurs en sciences humaines et sociales aux technologies de l’information et de la communication (TIC) dans leur activité d’enseignement, nous souhaitons nous focaliser dans cet article sur la compréhension des processus de socialisation professionnelle en jeu dans leur usage déclaré des TIC. Par socialisation professionnelle, nous e...

  17. Spectrally selective glazings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-08-01

    Spectrally selective glazing is window glass that permits some portions of the solar spectrum to enter a building while blocking others. This high-performance glazing admits as much daylight as possible while preventing transmission of as much solar heat as possible. By controlling solar heat gains in summer, preventing loss of interior heat in winter, and allowing occupants to reduce electric lighting use by making maximum use of daylight, spectrally selective glazing significantly reduces building energy consumption and peak demand. Because new spectrally selective glazings can have a virtually clear appearance, they admit more daylight and permit much brighter, more open views to the outside while still providing the solar control of the dark, reflective energy-efficient glass of the past. This Federal Technology Alert provides detailed information and procedures for Federal energy managers to consider spectrally selective glazings. The principle of spectrally selective glazings is explained. Benefits related to energy efficiency and other architectural criteria are delineated. Guidelines are provided for appropriate application of spectrally selective glazing, and step-by-step instructions are given for estimating energy savings. Case studies are also presented to illustrate actual costs and energy savings. Current manufacturers, technology users, and references for further reading are included for users who have questions not fully addressed here.

  18. Spectral analysis of linear relations and degenerate operator semigroups

    International Nuclear Information System (INIS)

    Baskakov, A G; Chernyshov, K I

    2002-01-01

    Several problems of the spectral theory of linear relations in Banach spaces are considered. Linear differential inclusions in a Banach space are studied. The construction of the phase space and solutions is carried out with the help of the spectral theory of linear relations, ergodic theorems, and degenerate operator semigroups

  19. Direction des Publications

    African Journals Online (AJOL)

    Synthese

    Unité de Recherche des Matériaux et des Energies Renouvelables (U.R.M.E.R). Université Abou –Baker Belkaid B.p : 119 Tlemcen 13000 Algerie. 2. Unité de Développement de la Technologie Du Silicium. UDTS, BP 399, Alger, Algérie. Accepté le : 08/06/2011. صخلم. داوﻣﻟا نﻣ ﻲﺗﻟا ﺔﺻﺎﺧو ،ﺔﻋﺎﻧﺻ يأ رﯾوطﺗ ﻲﻓ ﺎﯾﺳﯾﺋر ﻼﻣﺎﻋ ةرﯾﺧﻷا تاوﻧﺳﻟا ...

  20. Mykotische Infektionen des Penis

    Directory of Open Access Journals (Sweden)

    Mayser P

    1999-01-01

    Full Text Available Die häufigste mykotische Infektion des Penis stellt die Balanitis/Balonoposthitis durch Candida albicans dar. Sie weist eine steigende Inzidenz auf und scheint vornehmlich durch Genitalverkehr übertragen zu werden. Penile Infektionen durch Dermatophyten sind sehr selten, obwohl die Tinea inguinalis zu den häufigeren Erkrankungen zählt. Eine Mitbeteiligung des Penis im Rahmen von Systemmykosen kennzeichnet zumeist ein schwer verlaufende Erkrankung. Ursächlich kann beim immunoinkompetenten Patienten nahezu jeder Erreger in Frage kommen. Biopsie sowie Gewebekultur aus den meist ulzerativen Veränderungen können die Diagnose sichern. Die meisten superfiziellen Infektionen sprechen zufriedenstellend auf eine topische antimykotische Behandlung an, insbesondere wenn Provokationsfaktoren und die Möglichkeit der sexuellen Transmission berücksichtigt werden. Ausgedehnte Infektionen durch Dermatophyten, Hefen und natürlich systemische Infektionen erfordern eine systemische antimykotische Therapie.

  1. Chimie des processus biologiques

    OpenAIRE

    Fontecave, Marc

    2014-01-01

    Cours : Chimie biologique radicalaire : de l’origine de l’ADN au métabolisme d’aujourd’hui Il est généralement admis que les radicaux libres, espèces chimiques très réactives, sont des poisons pour les systèmes vivants qui ont élaboré des mécanismes efficaces pour s’en protéger et s’en débarrasser lorsqu’ils viennent à se former, par accident. Par exemple ce qu’on appelle communément le stress oxydant est une situation caractérisée par une accumulation de radicaux issus de l’oxygène moléculai...

  2. analyse de la variabilite des rendements du riz selon les varietes et ...

    African Journals Online (AJOL)

    ACSS

    15 févr. 2018 ... objectif, l'étude s'est basée sur une phase d'enquête basée sur un questionnaire intégré dans un Smartphone, et une autre phase d'observation, basée sur la mise en place des placettes et sous-placettes dans les champs des producteurs afin de recueillir les informations sur les pratiques culturales du riz ...

  3. La cogestion des Ressources naturelles

    International Development Research Centre (IDRC) Digital Library (Canada)

    L'eau, le sol, les nutriments, la lumière du soleil — ce sont des choses de la vie. .... habitent encore ces régions, soit de 9 % à 14 % de la population mondiale. ...... La guerre civile a fait vivre au Cambodge des années de chaos, d'anarchie et ...... et les allégeances politiques sont des facteurs qu'il est impossible d'ignorer.

  4. Des Ogle's old stump

    International Nuclear Information System (INIS)

    Jones, M.; Sutton, D.; Wallace, R.

    1998-01-01

    On 17 October 1997 Sylvia Bryan of RD4 Kaitaia wrote to 'Dear Somebody-Everybody' at the Anthropology Department, University of Auckland, urging further examination of an adzed stump found by Des Ogle during planting out of the Te Aupouri forest. The authors have since sought out relevant information and present it here for the interests of our readers. (author). 7 refs., 1 fig

  5. Santé de l'écosystème urbain à Katmandou, au Népal - phase III ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Les deux phases antérieures de ce projet (nos 003320 et 101277) ont permis la création et le renforcement de 18 groupes locaux ainsi que l'élaboration d'une nouvelle loi sur l'abattage des animaux et l'inspection des viandes, des amendements à la loi sur l'inspection des aliments et à la loi sur l'enlèvement des ordures ...

  6. Grundlagen des Tissue Engineering

    Science.gov (United States)

    Mayer, Jörg; Blum, Janaki; Wintermantel, Erich

    Die Organtransplantation stellt eine verbreitete Therapie dar, um bei krankheitsoder unfallbedingter Schädigung eines Organs die Gesamtheit seiner Funktionen wieder herzustellen, indem es durch ein Spenderorgan ersetzt wird. Organtransplantationen werden für die Leber, die Niere, die Lunge, das Herz oder bei schweren grossflächigen Verbrennungen der Haut vorgenommen. Der grosse apparative, personelle und logistische Aufwand und die Risiken der Transplantationschirurgie (Abstossungsreaktionen) sowie die mangelnde Verfügbarkeit von immunologisch kompatiblen Spenderorganen führen jedoch dazu, dass der Bedarf an Organtransplantaten nur zu einem sehr geringen Teil gedeckt werden kann. Sind Spenderorgane nicht verfügbar, können in einzelnen Fällen lebenswichtige Teilfunktionen, wie beispielsweise die Filtrationsfunktion der Niere durch die Blutreinigung mittels Dialyse ersetzt oder, bei mangelnder Funktion der Bauchspeicheldrüse (Diabetes), durch die Verabreichung von Insulin ein normaler Zustand des Gesamtorganismus auch über Jahre hinweg erhalten werden. Bei der notwendigen lebenslangen Anwendung apparativer oder medikamentöser Therapie können für den Patienten jedoch häufig schwerwiegende, möglicherweise lebensverkürzende Nebenwirkungen entstehen. Daher werden in der Forschung Alternativen gesucht, um die Funktionen des ausgefallenen Organs durch die Implantation von Zellen oder in vitro gezüchteten Geweben möglichst umfassend wieder herzustellen. Dies erfordert biologisch aktive Implantate, welche die für den Stoffwechsel des Organs wichtigen Zellen enthalten und einen organtypischen Stoffwechsel entfalten.

  7. Dictionnaire des risques psychosociaux

    CERN Document Server

    Zawieja, Philippe

    2014-01-01

    Stress, suicide, harcèlement, épuisement professionnel, workaholism... Au-delà de la souffrance qu'elles désignent, ces notions souvent récentes constituent une approche inédite, et demandent à mieux être comprises, dans leur ensemble et isolément. C'est tout l'enjeu de ce dictionnaire, pionnier en son genre. Le lecteur y trouvera représentés, avec les 314 entrées (rédigées par 251 contributeurs) qui le composent, tous les champs disciplinaires s'intéressant à la souffrance au travail : psychologie du travail et des organisations, psychologie sociale et psychosociologie, psychanalyse, psychopathologie et psychiatrie, ergonomie, sociologie du travail et des organisations, médecine du travail, droit du travail et de la sécurité sociale, sciences de gestion, philosophie... Y sont détaillés les principaux concepts, notions, approches, méthodes, théories, outils, études, etc., ayant cours dans l'étude des risques psychosociaux, mais aussi certaines professions emblématiques (infirmières,...

  8. Le vernis des apparences

    Directory of Open Access Journals (Sweden)

    Grazia Nicosia

    2010-04-01

    Full Text Available Le but de cet article est de comprendre l’incidence sémiotique du nettoyage d’un tableau ainsi que la résultante cognitive induite sur l’observateur. Cette étude confronte l’analyse des phénomènes visuels engendrés par le jaunissement du vernis et son retrait, à des entretiens réalisés à dessein. Le retrait d’un vernis jauni change considérablement l’image. L’heure, le climat, la saison et l’activité même des personnages s’en trouvent ainsi modifié. La patine peut être perçue, soit comme un obstacle à l’exploration, soit pour ceux qui l’apprécient, comme le medium d’une relation plus intime entre l’œuvre et l’observateur.The purpose of this article is to understand the semiotic impact of the cleaning of a painting and the cognitive effects induced on the observer. This study analyses conjointly the visual phenomenon generated by yellowing varnish and its removal and controlled interviews of observers.The removal of yellowing varnish modifies considerably the perception of the picture. Daytime, climate, season and characters activities are modified. The patina may be perceived either as an obstacle to the painting exploration, or, for those who appreciate it, as a medium for a closer relationship between the painting and the observer.

  9. Harmonische Reduktion des linken Ventrikels

    OpenAIRE

    Atila, M. (Mehmet)

    2005-01-01

    In der vorliegenden Arbeit wurde die harmonische Reduktion des linken Ventrikels am Modell des ausgewachsenen Hausschweins, unter Verwendung von Saugkappen variabler Größe untersucht. In 10 Schweinen mit Herzen normaler Größe und Funktion wurde eine Saugkappe, in Größe und Form an das abzufaltende Wandsegment angepasst, auf die epikardiale Oberfläche des schlagenden Herzens gesetzt. Wir führten Messungen der linksventrik. und der pulmonalart. Drücke, des ventrikulären Durchmessers und der Her...

  10. La recherche en action : des solutions locales, des effets durables ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    15 déc. 2010 ... Le Centre de recherches pour le développement international (CRDI) appuie la production et l'application de connaissances qui améliorent de façon notable la situation des habitants des pays en développement.

  11. Analyse des caractéristiques structurelles et des performances ...

    African Journals Online (AJOL)

    SARAH

    28 févr. 2014 ... performances technico-économiques de la riziculture irriguée en Côte d' .... en nous basant sur les prix des intrants et des produits en vigueur au cours ..... la recherche et de la vulgarisation et le transfert de technologies ; (2) ...

  12. Evaluation des pratiques de gestion des adventices en riziculture

    African Journals Online (AJOL)

    Les résultats ont montré que les méthodes de gestion de l'enherbement ont .... Le contrôle des adventices en riziculture irriguée a principalement .... mesurer la hauteur des plantes et la longueur ..... Performance agronomique du Sys- tème de ...

  13. Diversification des moyens de subsistance des petits producteurs de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    L'économie du Malawi repose essentiellement sur la culture du tabac, qui représente plus de 70 % des revenus d'exportation. Pour 60 % des 100 000 membres de la National Smallholder Farmers' Association of Malawi (NASFAM), le tabac est la seule et unique source de revenus. Les cultivateurs de tabac, au Malawi ...

  14. Roles et taches des accompagnateurs des patients hospitalises ...

    African Journals Online (AJOL)

    Roles et taches des accompagnateurs des patients hospitalises dans le service de pneumo-phtysiologie au Centre Hospitalier Universitaire Yalgado Ouedraogo de ... Logistical support represented by material support, drug supply, cleaning of premises, and littering occupied respectively 100%, 91%, 42% and 73%.

  15. Three-dimensional calculation of pollutant migration via compressible two-phase flow, for analysis of the methods of in situ air sparging and soil vapor extraction; Raeumliche Berechnung des Schadstofftransportes mit einer kompressiblen Zweiphasenstroemung zur Untersuchung der Drucklufteinblasung und Bodenluftabsaugung

    Energy Technology Data Exchange (ETDEWEB)

    Kuepper, S.

    1997-12-01

    In this study an analysis method is presented which allows numerical simulation of in situ air sparging coupled with soil vapor extraction. The improved FE-program takes the following phenomena into account: - Two-phase flow of compressible air and incompressible water - convective-dispersive contamination migration with air and water - transfer of volatile components from liquid phase to gas and water phase - sorption of contaminants onto soil - transfer of contaminants between air and water phase - biological processes. By means of back calculations of the results of laboratory experiments made by Eisele (1989) it was shown that with the developed program GWLCOND some of the necessary parameters for the numerical simulation of remedial systems can be determined. (orig./SR) [Deutsch] In dieser Arbeit wird ein Verfahren vorgestellt, mit dem eine numerische Simulation der Drucklufteinblasung und Bodenluftabsaugung durchgefuehrt werden kann. Das weiterentwickelte FE-Programmsystem beinhaltet folgende Ablaeufe: - Zweiphasenstroemung der kompressiblen Luft- und der inkompressiblen Wasserphase - Konvektiv-dispersiver Schadstofftransport mit der Gas- und der Wasserphase - Uebergang fluessiger Schadstoffe in die Gas- und in die Wasserphase - Sorption der Schadstoffe an der Feststoffphase - Uebergang der Schadstoffe zwischen der Gas- und der Wasserphase - Biologischer Abbau. Anhand der Nachrechnung eines Laborversuches von Eisele (1989) wird gezeigt, wie mit dem entwickelten Transportprogramm GWLCOND ein Teil der fuer die numerische Simulation des Sanierungsverfahrens benoetigten Kennwerte ermittelt werden kann. (orig./SR)

  16. CRISS power spectral density

    International Nuclear Information System (INIS)

    Vaeth, W.

    1979-04-01

    The correlation of signal components at different frequencies like higher harmonics cannot be detected by a normal power spectral density measurement, since this technique correlates only components at the same frequency. This paper describes a special method for measuring the correlation of two signal components at different frequencies: the CRISS power spectral density. From this new function in frequency analysis, the correlation of two components can be determined quantitatively either they stem from one signal or from two diverse signals. The principle of the method, suitable for the higher harmonics of a signal as well as for any other frequency combinations is shown for the digital frequency analysis technique. Two examples of CRISS power spectral densities demonstrates the operation of the new method. (orig.) [de

  17. Photovoltaic spectral responsivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Emery, K.; Dunlavy, D.; Field, H.; Moriarty, T. [National Renewable Energy Lab., Golden, CO (United States)

    1998-09-01

    This paper discusses the various elemental random and nonrandom error sources in typical spectral responsivity measurement systems. The authors focus specifically on the filter and grating monochrometer-based spectral responsivity measurement systems used by the Photovoltaic (PV) performance characterization team at NREL. A variety of subtle measurement errors can occur that arise from a finite photo-current response time, bandwidth of the monochromatic light, waveform of the monochromatic light, and spatial uniformity of the monochromatic and bias lights; the errors depend on the light source, PV technology, and measurement system. The quantum efficiency can be a function of he voltage bias, light bias level, and, for some structures, the spectral content of the bias light or location on the PV device. This paper compares the advantages and problems associated with semiconductor-detector-based calibrations and pyroelectric-detector-based calibrations. Different current-to-voltage conversion and ac photo-current detection strategies employed at NREL are compared and contrasted.

  18. Spectral analysis by correlation

    International Nuclear Information System (INIS)

    Fauque, J.M.; Berthier, D.; Max, J.; Bonnet, G.

    1969-01-01

    The spectral density of a signal, which represents its power distribution along the frequency axis, is a function which is of great importance, finding many uses in all fields concerned with the processing of the signal (process identification, vibrational analysis, etc...). Amongst all the possible methods for calculating this function, the correlation method (correlation function calculation + Fourier transformation) is the most promising, mainly because of its simplicity and of the results it yields. The study carried out here will lead to the construction of an apparatus which, coupled with a correlator, will constitute a set of equipment for spectral analysis in real time covering the frequency range 0 to 5 MHz. (author) [fr

  19. Spectral backward radiation profile

    International Nuclear Information System (INIS)

    Kwon, Sung Duck; Lee, Keun Hyun; Kim, Bo Ra; Yoon, Suk Soo

    2004-01-01

    Ultrasonic backward radiation profile is frequency-dependent when incident region has deptional gradient of acoustical properties or multi-layers. Until now, we have measured the profiles of principal frequencies of used transducers so that it was not easy to understand the change of the frequency component and spectrum of backward radiation from the profile. We tried to measure the spectral backward radiation profiles using DFP(digital filer package) Lecroy DSO. The very big changes in the shape and pattern of spectral backward radiation profiles leads to the conclusion that this new try could be very effective tool to evaluate frequency dependent surface area.

  20. Utilisation sans risque des eaux usées, des excréta et des eaux ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Les responsables de ce projet piloteront l'application et l'adaptation des principes directeurs relatifs à l'utilisation sans risque des eaux usées, des excreta et des eaux grises en agriculture et en aquaculture (Guidelines for the Safe Use of Wastewater, Excreta and Greywater in Agriculture and Aquaculture), que ...

  1. Analyse sexospécifique et générationnelle des conflits armés et des ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Les phases antérieures ont été financées dans le cadre du projet no 102081, Questions de genre et de génération dans les conflits armés, les processus de paix et de justice et le désarmement, et du projet no 103312, Analyse sexospécifique et générationnelle des conflits armés et des processus de paix et de justice ...

  2. Direction des Publications

    African Journals Online (AJOL)

    Synthese

    mélange pulvérulent de coke et de calcaire. La réduction est assurée par le gaz CO à 1250°C [2]. Le procédé Kawazaki iron powder utilise la calamine comme matière première et aussi CO comme gaz réducteur pour élaborer des poudres de fer. [3]. Un autre procédé plus connu qui fabrique les poudres de fer à partir de la.

  3. Glossaire des sigles

    OpenAIRE

    2015-01-01

    ABM Anti-ballistic missile = Missile antimissile balistique AGM Air-to-ground missile = Missile air-sol AIEA Agence Internationale de l’Energie Atomique ALCM Air-launched cruise missile = Missile de croisière air-sol ANSEA Association des Nations du Sud-Est asiatique ANT* Arme nucléaire tactique ASAT Anti-satellite = Arme antisatellite ASW Anti-submarine warfare = Guerre anti-sous-marine AWACS Airborne warning and control system = Système aérien de contrôle et d’alerte BMD Ballistic missile d...

  4. Counter-IED Initiative PPE Horizon 0, Phase 1, Protection Versus Performance Preliminary Trade-off Analysis, Behavioural Task Analysis (Initiative d’epi pour la Lutte aux IED - Horizon 0 Phase 1 - Analyse de Compromis Preliminaire de la Protection par Rapport au Rendement Analyse Comportementale des Taches)

    Science.gov (United States)

    2007-05-01

    fournit les connaissances spécialisées en ergonomie pour soutenir ce projet. Afin de formuler des recommandations relativement à l’EPI pour corriger...important. RDDC Toronto fournit les connaissances spécialisées en ergonomie pour soutenir ce projet. Afin de formuler des recommandations relativement à...Programme de démonstration de technologie (PDT) de C−IED plus important. RDDC Toronto fournit les connaissances spécialisées en ergonomie pour soutenir

  5. De l'importance des orbites periodiques: Detection et applications

    Science.gov (United States)

    Doyon, Bernard

    L'ensemble des Orbites Periodiques Instables (OPIs) d'un systeme chaotique est intimement relie a ses proprietes dynamiques. A partir de l'ensemble (en principe infini) d'OPIs cachees dans l'espace des phases, on peut obtenir des quantites dynamiques importantes telles les exposants de Lyapunov, la mesure invariante, l'entropie topologique et la dimension fractale. En chaos quantique (i.e. l'etude de systemes quantiques qui ont un equivalent chaotique dans la limite classique), ces memes OPIs permettent de faire le pont entre le comportement classique et quantique de systemes non-integrables. La localisation de ces cycles fondamentaux est un probleme complexe. Cette these aborde dans un premier temps le probleme de la detection des OPIs dans les systemes chaotiques. Une etude comparative de deux algorithmes recents est presentee. Nous approfondissons ces deux methodes afin de les utiliser sur differents systemes dont des flots continus dissipatifs et conservatifs. Une analyse du taux de convergence des algorithmes est aussi realisee afin de degager les forces et les limites de ces schemes numeriques. Les methodes de detection que nous utilisons reposent sur une transformation particuliere de la dynamique initiale. Cette astuce nous a inspire une methode alternative pour cibler et stabiliser une orbite periodique quelconque dans un systeme chaotique. Le ciblage est en general combine aux methodes de controle pour stabiliser rapidement un cycle donne. En general, il faut connaitre la position et la stabilite du cycle en question. La nouvelle methode de ciblage que nous presentons ne demande pas de connaitre a priori la position et la stabilite des orbites periodiques. Elle pourrait etre un outil complementaire aux methodes de ciblage et de controle actuelles.

  6. Spectral Ensemble Kalman Filters

    Czech Academy of Sciences Publication Activity Database

    Mandel, Jan; Kasanický, Ivan; Vejmelka, Martin; Fuglík, Viktor; Turčičová, Marie; Eben, Kryštof; Resler, Jaroslav; Juruš, Pavel

    2014-01-01

    Roč. 11, - (2014), EMS2014-446 [EMS Annual Meeting /14./ & European Conference on Applied Climatology (ECAC) /10./. 06.10.2014-10.10.2014, Prague] R&D Projects: GA ČR GA13-34856S Grant - others:NSF DMS-1216481 Institutional support: RVO:67985807 Keywords : data assimilation * spectral filter Subject RIV: DG - Athmosphere Sciences, Meteorology

  7. Mechanical spectral shift reactor

    International Nuclear Information System (INIS)

    Sherwood, D.G.; Wilson, J.F.; Salton, R.B.; Fensterer, H.F.

    1981-01-01

    A mechanical spectral shift reactor comprises apparatus for inserting and withdrawing water displacer elements from the reactor core for selectively changing the water-moderator volume in the core thereby changing the reactivity of the core. The apparatus includes drivemechanisms for moving the displacer elements relative to the core and guide mechanisms for guiding the displayer rods through the reactor vessel

  8. Mechanical spectral shift reactor

    International Nuclear Information System (INIS)

    Sherwood, D.G.; Wilson, J.F.; Salton, R.B.; Fensterer, H.F.

    1982-01-01

    A mechanical spectral shift reactor comprises apparatus for inserting and withdrawing water displacer elements from the reactor core for selectively changing the water-moderator volume in the core thereby changing the reactivity of the core. The apparatus includes drive mechanisms for moving the displacer elements relative to the core and guide mechanisms for guiding the displacer rods through the reactor vessel. (author)

  9. Isolement et identification des levures.

    Directory of Open Access Journals (Sweden)

    S. DOMERCQ

    1967-06-01

    Full Text Available La fermentation du moût de raisin est assurée par les levures qui se trouvent sur la pellicule du raisin, sur les rafles, et aussi, par celles qui envahissent le matériel de vendange et de vinification dès que la récolte est commencée. L'apparition deLa fermentation du moût de raisin est assurée par les levures qui se trouvent sur la pellicule du raisin, sur les rafles, et aussi, par celles qui envahissent le matériel de vendange et de vinification dès que la récolte est commencée. L'apparition des signes de la fermentation est spontanée. La fermentation est rapide dans la majorité des cas, si elle devient trop violente et que la température s'élève dangeureusement, il faut la « canaliser », la calmer. Des accidents peuvent se produire; des arrêts de fermentation laissant des sucres non fermentés pouvant être attaqués par d'autres microorganismes, des développements de levures formant des substances nuisibles à la qualité; par la suite, il s'agit d'obtenir la stabilité du vin, en particulier, éviter les refermentations des vins doux. L'étude de ces problèmes nécessite une étude préliminaire, celle des levures responsables de la fermentation alcoolique du jus de raisin, qui ne peut être faite que sur des cultures pures, isolées au préalable à l'aide de prélèvements soigneusement réalisés.s signes de la fermentation est spontanée. La fermentation est rapide dans la majorité des cas, si elle devient trop violente et que la température s'élève dangeureusement, il faut la « canaliser », la calmer. Des accidents peuvent se produire; des arrêts de fermentation laissant des sucres non fermentés pouvant être attaqués par d'autres microorganismes, des développements de levures formant des substances nuisibles à la qualité; par la suite, il s'agit d'obtenir la stabilité du vin, en particulier, éviter les refermentations des vins doux. L'étude de ces problèmes nécessite une étude pr

  10. Le Débat des semences

    International Development Research Centre (IDRC) Digital Library (Canada)

    Solutions pour les lois nationales régissant le contrôle des ressources génétiques et des ...... des pouvoirs) qui reconnaissent, dans une certaine mesure, les droits de gestion collectifs des ...... documentés, les performances physiques, etc.

  11. Mécanique des sols et des roches

    CERN Document Server

    Vullier, Laurent; Zhao, Jian

    2016-01-01

    La mécanique des sols et la mécanique des roches sont des disciplines généralement traitées séparément dans la littérature. Pour la première fois, un traité réunit ces deux spécialités, en intégrant également les connaissances en lien avec les écoulements souterrains et les transferts thermiques. A la fois théorique et pratique, cet ouvrage propose tout d'abord une description détaillée de la nature et de la composition des sols et des roches, puis s'attache à la modélisation de problèmes aux conditions limites et présente les essais permettant de caractériser les sols et les roches, tant d'un point de vue mécanique qu'hydraulique et thermique. La problématique des sols non saturés et des écoulements multiphasiques est également abordée. Une attention particulière est portée aux lois de comportement mécanique et à la détermination de leurs paramètres par des essais in situ et en laboratoire, et l'ouvrage offre également une présentation détaillée des systèmes de classi...

  12. A Simple Spectral Observer

    Directory of Open Access Journals (Sweden)

    Lizeth Torres

    2018-05-01

    Full Text Available The principal aim of a spectral observer is twofold: the reconstruction of a signal of time via state estimation and the decomposition of such a signal into the frequencies that make it up. A spectral observer can be catalogued as an online algorithm for time-frequency analysis because is a method that can compute on the fly the Fourier transform (FT of a signal, without having the entire signal available from the start. In this regard, this paper presents a novel spectral observer with an adjustable constant gain for reconstructing a given signal by means of the recursive identification of the coefficients of a Fourier series. The reconstruction or estimation of a signal in the context of this work means to find the coefficients of a linear combination of sines a cosines that fits a signal such that it can be reproduced. The design procedure of the spectral observer is presented along with the following applications: (1 the reconstruction of a simple periodical signal, (2 the approximation of both a square and a triangular signal, (3 the edge detection in signals by using the Fourier coefficients, (4 the fitting of the historical Bitcoin market data from 1 December 2014 to 8 January 2018 and (5 the estimation of a input force acting upon a Duffing oscillator. To round out this paper, we present a detailed discussion about the results of the applications as well as a comparative analysis of the proposed spectral observer vis-à-vis the Short Time Fourier Transform (STFT, which is a well-known method for time-frequency analysis.

  13. Les reseaux de politique publique comme facteur d'influence du choix des instruments de politique energetique canadienne a des fins environnementales de 1993 a nos jours

    Science.gov (United States)

    Fathy El Dessouky, Naglaa

    l'agenda politique du pays. Notre projet de recherche, par le truchement de l'approche des reseaux de politique publique, s'attarde a decrire et a expliquer le processus de la formulation d'une politique particuliere, soit la politique energetique a des fins de protection de l'environnement, elaboree en 1993. Il s'agit de mettre en evidence les facteurs affectant le choix des instruments de ces politiques publiques dans leur contexte national. Ainsi, la question generale de cette recherche est: Comment les phases evolutives de la formation d'un reseau de politique, en l'occurrence le Conseil canadien de l'energie (CCE), menent a des caracteristiques particulieres a ce reseau; et comment celles-ci determinent-elles les types des instruments de politique publique choisis, particulierement ceux de la recente orientation des politiques energetiques canadiennes a des fins environnementales elaborees en 1993? Afin d'atteindre l'objectif de notre recherche, deux facteurs primordiaux sont utilises, soit la circulation de l'information et l'exercice du controle sur les ressources des acteurs. L'analyse des caracteristiques du reseau en fonction des liens forts et des liens faibles autant que la presence ou l'absence des trous structuraux nous permettent de bien identifier les positions des differents acteurs, etatiques et non etatiques, sur le plan de l'information et du controle, qui a leur tour, nous semble-t-il, constituent des facteurs affectant les types des instruments des politiques publiques choisis: instruments substantifs, qui indiquent le degre de l'intervention du gouvernement, et instruments proceduraux, qui mettent plutot l'accent sur le degre de l'influence du gouvernement sur les acteurs non etatiques. L'etude soutient que l'approche des reseaux se distingue notamment par son potentiel a expliquer l'interrelation relative entre idees, interets et institutions, ce qui a son tour est susceptible de permettre une meilleure comprehension des processus de l

  14. Avancement des travaux électriques LHC point 1

    CERN Document Server

    Delidais, M

    2001-01-01

    Après la première phase d'analyse des principes de la distribution en électricité de la zone 1 du LHC et de l'expérience ATLAS, les études sont à présent orientées vers la définition des implantations des principaux équipements tels que transformateurs, tableaux basse tension, alimentations statiques de sécurité, ainsi que vers la détermination du cheminement des câbles dans les ouvrages de surface et à travers les ouvrages souterrains USA15, UX15 et les galeries de liaison. Les études des services généraux sont également menées pour les bâtiments de surface qui seront mis prochainement à disposition par le génie civil, en particulier la station de refroidissement SF1 ainsi que le bâtiment SUX1 pour lesquels les travaux d'installation devraient débuter sous peu pour être achevés dans le premier trimestre 2001.

  15. Chirurgie des grassmanniennes

    CERN Document Server

    Lafforgue, Laurent

    2003-01-01

    Les compactifications diverses de variétés de modules sont un thème important et récurrent des mathématiques modernes, et elles connaissent un grand nombre d'applications. Ce livre traite le cas de cellules de Schubert minces, qui sont de sous-variétés naturelles de grassmanniennes. L'auteur a été amené à traiter ces questions par un cas particulier lié à ses travaux sur le programme de Langlands. Dans cette monographie, il en développe une théorie plus systématique, présentant le fortes similarités avec celle des modules du courbes stables. The various compactifications of moduli spaces are an important recurrent theme of modern mathematics, and they have a large number of applications. This book treats the case of thin Schubert varieties, which are natural subvarieties of Grassmannians. The author was led to these questions by a particular case linked to his work on the Langlands program. In this monograph, he develops the theory in a more systematic way, which exhibits strong similarities...

  16. Comportement des polluants des eaux pluviales urbaines en ...

    African Journals Online (AJOL)

    développement et la croissance des organismes vivant dans l'eau et particulièrement les micro- organismes. Le suivi des températures enregistrées oscille entre 9 et 16°C dans les trois sites d'observation durant la période ... de la lumière du soleil. Le site C est bien aéré et .... Effets de différents modes de gestion des eaux ...

  17. La cassitérite zonée du gisement de Sokhret Allal (granite des Zaër ; Maroc central) : composition chimique et phases fluides associées

    OpenAIRE

    Giuliani, Gaston

    1987-01-01

    La composition chimique d'une cassitérite zonée provenant du gisement de tungstène-étain de Sokhret Allal (Maroc central) a été analysée par microsonde électronique. La zonation optique du minéral correspond à des variations en éléments mineurs tels Fe et Ti. Les inclusions fluides contemporaines du dépôt de la cassitérite sont primaires et constituées de fluides typiquement aqueux appartenant au système H2O-NaCl. La contribution de ces nouvelles données dans la métallogenèse W-Sn du Maroc ce...

  18. Approche historique des classifications en psychiatrie

    OpenAIRE

    Garrabé , J.

    2011-01-01

    Resume Des le milieu du xixe siecle s?est posee la question des criteres de classification des maladies. Pour les maladies mentales, diverses classifications ont alors ete proposees par des auteurs francais (Morel) et allemands (Kahlbaum, Kraepelin). A partir de la fin du xixe siecle, le Bureau International de Statistique (Paris) a publie a une Classification Internationale des Maladies, a revision decennale (J. Bertillon). Cette tache a ete poursuivie dans l?entre-deux-guerres pa...

  19. Complications du traitement traditionnel des fractures : aspects ...

    African Journals Online (AJOL)

    Tous les patients reçus avec des complications du traitement traditionnel des fractures ont été inclus dans ce travail. Le diagnostic des lésions était clinique et radiologique. Nous avions reçu 51 patients porteurs de complications suite à des traitements de médecine traditionnelle, soit 13,7% du total des patients hospitalisés ...

  20. Des cartes dans la classe…

    Directory of Open Access Journals (Sweden)

    R. Gimeno

    1990-09-01

    Full Text Available La majorité des enseignants qui veulent faire des cartes — et les faire réaliser aux élèves — pour répondre aux exigences des instructions officielles, doivent surmonter leur manque de compétences en cartographie et en didactique ainsi que les difficultés propres aux logiciels de cartographie encore peu performants. Ces compétences et la réflexion qui les accompagne sont pourtant accessibles aux enfants de l’école élémentaire…

  1. Measurements of spectral indices in homogeneous multiplying media; Mesures d'indices de spectre dans les milieux multiplicateurs homogenes

    Energy Technology Data Exchange (ETDEWEB)

    Bruna, J G; Brunet, J P; Clouet D' Orval, Ch; Verriere, Ph; Kremser, J; Moret-Bailly, J; Tellier, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    Methods for computation of spectra in light water are developed at Saclay and it is interesting to carry out at the same time experimental studies of simple media such as solutions of fissionable salts which allow quite direct comparisons with computed values. The spectral indices measurements were made with two small fission chambers, one containing deposited plutonium, the other deposited uranium 235. Their response, when neutron spectrum is modified, allows to study the epithermal part of the flux. The media studied with these chambers are fissionable solutions (of plutonium or 90 per cent enriched uranium) which were made critical in bare cylindrical geometry in the Alecto reactor. If the ratio of the chambers is normalized to unity in a Maxwell spectrum, then the noted variation of the ratio of the counts Pu chamber/ U{sup 235} chamber reaches 1,4 in the range of the studied concentrations. (authors) [French] Des calculs de spectres dans l'eau legere sont mis au point a Saclay et il est interessant de mener parallelement des etudes experimentale sur des milieux simples tels que des solutions de sels fissiles, qui permettent des comparaisons tres directes avec les valeurs calculees. On a choisi d'effectuer des mesures d' 'indices de spectres' a l'aide de de deux petites chambres a fission contenant des depots, l'une de plutonium, l'autre d'uranium 235. Leur reponse lorsque le spectre des neutrons est modifie permet d'etudier la partie epithermique du flux. Les milieux etudies a l'aide de ces chambres sont des solutions fissiles (plutonium ou uranium enrichi a 90 pour cent) rendus critiques, en geometrie cylindrique nue, dans le reacteur Alecto. Si le rapport des chambres est normalise a un dans un spectre de Maxwell, la variation constatee du rapport des comptages chambre Pu/ chambre U{sup 235} atteint, dans les gammes de concentrations etudiees, 1,4. (auteurs)

  2. Diversification des moyens de subsistance des petits producteurs de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Cette subvention permettra à l'Institut international de recherche sur les cultures des zones tropicales ... In ROSSA's latest bulletin issue: A farewell message from Simon Carter, the Regional Director of the ... Cigarette Taxation in Tanzania.

  3. Composes inter-halogenes sous pression: etude des transformations structurales dans le monobromure d'iode sous forme dense

    Science.gov (United States)

    Bouchard, Alexandre

    La famille des composes halogenes et inter-halogenes representent des solides moleculaires adoptant des phases denses communes avec des solides moleculaires diatomiques comme l'azote et l'hydrogene. Parmi les transformations structurales et electroniques induites sous haute pression et observees dans ces solides, on note, entre autres, la dissociation moleculaire et la metallisation. De plus, l'etude des phases denses de l'iode a permis recemment l'observation d'une structure cristalline possedant une modulation dite incommensurable, c'est-a-dire une modulation possedant une periodicite differente de celle de la structure cristalline, jetant ainsi une lumiere nouvelle sur le processus de dissociation moleculaire dans les solides halogenes. Dans ce memoire, on propose d'etudier les changements structuraux dans monobromure d'iode (IBr), un compose inter-halogene possedant des proprietes structurales semblables a celles de deux composes halogenes, soit l'iode (I 2) et le brome (Br2) sous leur forme solide. Des experiences de diffraction des rayons X de poudres en utilisant un rayonnement synchrotron ont ete realisees a temperature ambiante sur l'IBr en variant la pression jusqu'aux environs de 60 GPa. La nature chimique particuliere du compose IBr a necessite la mise au point de techniques de chargement d'echantillon destinees a preserver l'integrite chimique de la substance utilisee. On rapporte egalement l'observation d'une phase de l'IBr presentant une modulation incommensurable. Les phases observees dans l'IBr permettent d'etablir des paralleles avec les phases denses rapportees dans I2 et Br2 par le biais d'un modele phenomenologique decrivant la sequence structurale des solides halogenes sous forme condensee.

  4. L'exode des cerveaux et le renforcement des capacités en Afrique ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    1 févr. 2011 ... Ce phénomène ébranle les assises économiques et politiques de bien des pays africains. ... le défi consiste à recruter ces cerveaux. ... des missions africaines, des organisations non gouvernementales et des groupes de la diaspora réunis pour parler de l'exode des cerveaux en Afrique et des stratégies à ...

  5. Evaluation des pratiques de gestion des adventices en riziculture ...

    African Journals Online (AJOL)

    Le riz est l'aliment principal pour la quasi-totalité des populations vivant en Côte d'Ivoire. Cependant, les adventices sont considérées comme la contrainte biologique la plus importante faisant obstacle à la production rizicole. L'objectif de cette étude menée en 2015 était d'évaluer différentes techniques de gestion des ...

  6. Cartographie des zones d'intervention des partenaires techniques et ...

    African Journals Online (AJOL)

    cartographier les zones d'intervention des partenaires techniques et financiers au Bénin. L'approche méthodologique utilisée a consisté à la recherche documentaire, à la collecte de données auprès des partenaires techniques et financiers et à l'analyse de ces données. Les résultats ont permis de constater que cent dix ...

  7. Modernisation des marchés agroalimentaires - inclusion des petits ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Les marchés agroalimentaires connaissent de rapides changements dans les pays en développement et les pays en transition. Sous l'influence de la libéralisation du commerce et des nouvelles technologies de transformation des aliments et de commerce de détail, les marchés agroalimentaires évoluent vers une plus ...

  8. Hybrid spectral CT reconstruction.

    Directory of Open Access Journals (Sweden)

    Darin P Clark

    Full Text Available Current photon counting x-ray detector (PCD technology faces limitations associated with spectral fidelity and photon starvation. One strategy for addressing these limitations is to supplement PCD data with high-resolution, low-noise data acquired with an energy-integrating detector (EID. In this work, we propose an iterative, hybrid reconstruction technique which combines the spectral properties of PCD data with the resolution and signal-to-noise characteristics of EID data. Our hybrid reconstruction technique is based on an algebraic model of data fidelity which substitutes the EID data into the data fidelity term associated with the PCD reconstruction, resulting in a joint reconstruction problem. Within the split Bregman framework, these data fidelity constraints are minimized subject to additional constraints on spectral rank and on joint intensity-gradient sparsity measured between the reconstructions of the EID and PCD data. Following a derivation of the proposed technique, we apply it to the reconstruction of a digital phantom which contains realistic concentrations of iodine, barium, and calcium encountered in small-animal micro-CT. The results of this experiment suggest reliable separation and detection of iodine at concentrations ≥ 5 mg/ml and barium at concentrations ≥ 10 mg/ml in 2-mm features for EID and PCD data reconstructed with inherent spatial resolutions of 176 μm and 254 μm, respectively (point spread function, FWHM. Furthermore, hybrid reconstruction is demonstrated to enhance spatial resolution within material decomposition results and to improve low-contrast detectability by as much as 2.6 times relative to reconstruction with PCD data only. The parameters of the simulation experiment are based on an in vivo micro-CT experiment conducted in a mouse model of soft-tissue sarcoma. Material decomposition results produced from this in vivo data demonstrate the feasibility of distinguishing two K-edge contrast agents with

  9. Hybrid spectral CT reconstruction

    Science.gov (United States)

    Clark, Darin P.

    2017-01-01

    Current photon counting x-ray detector (PCD) technology faces limitations associated with spectral fidelity and photon starvation. One strategy for addressing these limitations is to supplement PCD data with high-resolution, low-noise data acquired with an energy-integrating detector (EID). In this work, we propose an iterative, hybrid reconstruction technique which combines the spectral properties of PCD data with the resolution and signal-to-noise characteristics of EID data. Our hybrid reconstruction technique is based on an algebraic model of data fidelity which substitutes the EID data into the data fidelity term associated with the PCD reconstruction, resulting in a joint reconstruction problem. Within the split Bregman framework, these data fidelity constraints are minimized subject to additional constraints on spectral rank and on joint intensity-gradient sparsity measured between the reconstructions of the EID and PCD data. Following a derivation of the proposed technique, we apply it to the reconstruction of a digital phantom which contains realistic concentrations of iodine, barium, and calcium encountered in small-animal micro-CT. The results of this experiment suggest reliable separation and detection of iodine at concentrations ≥ 5 mg/ml and barium at concentrations ≥ 10 mg/ml in 2-mm features for EID and PCD data reconstructed with inherent spatial resolutions of 176 μm and 254 μm, respectively (point spread function, FWHM). Furthermore, hybrid reconstruction is demonstrated to enhance spatial resolution within material decomposition results and to improve low-contrast detectability by as much as 2.6 times relative to reconstruction with PCD data only. The parameters of the simulation experiment are based on an in vivo micro-CT experiment conducted in a mouse model of soft-tissue sarcoma. Material decomposition results produced from this in vivo data demonstrate the feasibility of distinguishing two K-edge contrast agents with a spectral

  10. Mechanical spectral shift reactor

    International Nuclear Information System (INIS)

    Wilson, J.F.; Sherwood, D.G.

    1982-01-01

    A mechanical spectral shift reactor comprises a reactive core having fuel assemblies accommodating both water displacer elements and neutron absorbing control rods for selectively changing the volume of water-moderator in the core. The fuel assemblies with displacer and control rods are arranged in alternating fashion so that one displacer element drive mechanism may move displacer elements in more than one fuel assembly without interfering with the movement of control rods of a corresponding control rod drive mechanisms. (author)

  11. Speech recognition from spectral dynamics

    Indian Academy of Sciences (India)

    Carrier nature of speech; modulation spectrum; spectral dynamics ... the relationships between phonetic values of sounds and their short-term spectral envelopes .... the number of free parameters that need to be estimated from training data.

  12. Demolition of the FRJ-1 research reactor (MERLIN); Abbau des Reaktorblocks des Forschungsreaktors FRJ-1 (MERLIN)

    Energy Technology Data Exchange (ETDEWEB)

    Stahn, B.; Matela, K.; Zehbe, C. [Forschungszentrum Juelich GmbH (Germany); Poeppinghaus, J. [Gesellschaft fuer Nuklearservice, Essen (Germany); Cremer, J. [SNT Siempelkamp Nukleartechnik, Heidelberg (Germany)

    2003-06-01

    FRJ-2 (MERLIN), the swimming pool reactor cooled and moderated by light water, was built at the then Juelich Nuclear Research Establishment (KFA) between 1958 and 1962. In the period between 1964 and 1985, it was used for. The reactor was decommissioned in 1985. Since 1996, most of the demolition work has been carried out under the leadership of a project team. The complete secondary cooling system was removed by late 1998. After the cooling loops and experimental installations had been taken out, the reactor vessel internals were removed in 2000 after the water had been drained from the reactor vessel. After the competent authority had granted a license, demolition of the reactor block, the central part of the research reactor, was begun in October 2001. In a first step, the reactor operating floor and the reactor attachment structures were removed by the GNS/SNT consortium charged with overall planning and execution of the job. This phase gave rise to approx. The reactor block proper is dismantled in a number of steps. A variety of proven cutting techniques are used for this purpose. Demolition of the reactor block is to be completed in the first half of 2003. (orig.) [German] Der mit Leichtwasser gekuehlte und moderierte Schwimmbad-Forschungsreaktor FRJ-2 (MERLIN) wurde von 1958 bis 1962 fuer die damalige Kernforschungsanlage Juelich (KFA) errichtet. Von 1964 bis 1985 wurde er fuer Experimente mit zunaechst 5 MW und spaeter 10 MW thermischer Leistung bei einem maximalen thermischen Neutronenfluss von 1,1.10{sup 14} n/cm{sup 2}s genutzt. Im Jahr 1985 stellte der Reaktor seinen Betrieb ein. Die Brennelemente wurden aus der Anlage entfernt und in die USA und nach Grossbritannien verbracht. Seit 1996 erfolgen die wesentlichen Abbautaetigkeiten unter Leitung eines verantwortlichen Projektteams. Bis Ende 1998 wurde das komplette Sekundaerkuehlsystem entfernt. Dem Abbau der Kuehlkreislaeufe und Experimentiereinrichtungen folgte im Jahr 2000 der Ausbau der

  13. Der Zellzyklusregulator Rca1 - Inhibitor und Substrat des Anaphase-Promoting-Komplexes in Drosophila melanogaster

    OpenAIRE

    Morgenthaler, Christoph

    2014-01-01

    Ein wichtiger Kontrollmechanismus des Zellzyklus ist die irreversible Proteolyse von Zellzyklus-Regulatoren. Dabei markieren E3-Ligasen Zielproteine durch Ubiquitinmoleküle. Für den Abbau in der Mitose und der G1-Phase reguliert der APC/C-Komplex (Anaphase-Promoting-Complex/Cyclosome) als E3-Ligase den zeitlichen Verlauf des Zellzyklus. Die Aktivität des APC/C wiederum wird in den übrigen Zellzyklusstadien durch Phosphorylierung und durch Proteine der Rca1/Emi1-Proteinfamilie inaktiv gehalten...

  14. Die Versprachlichung des Sakralen

    DEFF Research Database (Denmark)

    Larsen, Øjvind

    2011-01-01

    transformation of the sacred as a harmonious theory of secularization. However, if we follow Weber in his religious-sociological considerations of modernity, we reach a tragic theory of secularization that poses the real problem that modernity’s connection to the sacred has been dissolved.......Habermas claims in connection with his development of the theory of communicative action that the sacred is transformed in a positive way and can take the form of free deliberation in society, the so-called Versprachlichung des Sakralen. The thesis is that the authority which could be found...... in religion and which is of fundamental significance for the integration of pre-modern societies is taken over by modern societies in forms of deliberation. Habermas develops his thesis in a discussion of Durkheim’s religious-sociological considerations. Habermas presents his thesis about the linguistic...

  15. Code des baux 2018

    CERN Document Server

    Vial-Pedroletti, Béatrice; Kendérian, Fabien; Chavance, Emmanuelle; Coutan-Lapalus, Christelle

    2017-01-01

    Le code des baux 2018 vous offre un contenu extrêmement pratique, fiable et à jour au 1er août 2017. Cette 16e édition intègre notamment : le décret du 27 juillet 2017 relatif à l’évolution de certains loyers dans le cadre d’une nouvelle location ou d’un renouvellement de bail, pris en application de l’article 18 de la loi n° 89-462 du 6 juillet 1989 ; la loi du 27 janvier 2017 relative à l’égalité et à la citoyenneté ; la loi du 9 décembre 2016 relative à la transparence, à la lutte contre la corruption et à la modernisation de la vie économique ; la loi du 18 novembre 2016 de modernisation de la justice du xxie siècle

  16. Spectrally resolved digital holography using a white light LED

    Science.gov (United States)

    Claus, D.; Pedrini, G.; Buchta, D.; Osten, W.

    2017-06-01

    This paper introduces the concept of spectrally resolved digital holography. The measurement principle and the analysis of the data will be discussed in detail. The usefulness of spectrally resolved digital holography is demonstrated for colour imaging and optical metrology with regards to the recovery of modulus information and phase information, respectively. The phase information will be used to measure the shape of an object via the application of the dual wavelength method. Based on the large degree of data available, multiple speckle de-correlated dual wavelength phase maps can be obtained, which when averaged result in a signal to noise ratio improvement.

  17. Digitalisierung des Kulturellen Erbes (Europas)

    NARCIS (Netherlands)

    Gruber, Marion

    2011-01-01

    Gruber, M. R. (2011, 13 December). Digitalisierung des Kulturellen Erbes (Europas). Guest lecture at the IPMZ - Institute of Mass Communication and Media Research, Devision Media Change & Innovation, University of Zurich, Switzerland.

  18. Vecteurs Singuliers des Theories des Champs Conformes Minimales

    Science.gov (United States)

    Benoit, Louis

    En 1984 Belavin, Polyakov et Zamolodchikov revolutionnent la theorie des champs en explicitant une nouvelle gamme de theories, les theories quantiques des champs bidimensionnelles invariantes sous les transformations conformes. L'algebre des transformations conformes de l'espace-temps presente une caracteristique remarquable: en deux dimensions elle possede un nombre infini de generateurs. Cette propriete impose de telles conditions aux fonctions de correlations qu'il est possible de les evaluer sans aucune approximation. Les champs des theories conformes appartiennent a des representations de plus haut poids de l'algebre de Virasoro, une extension centrale de l'algebre conforme du plan. Ces representations sont etiquetees par h, le poids conforme de leur vecteur de plus haut poids, et par la charge centrale c, le facteur de l'extension centrale, commune a toutes les representations d'une meme theorie. Les theories conformes minimales sont constituees d'un nombre fini de representations. Parmi celles-ci se trouvent des theories unitaires dont les representation forment la serie discrete de l'algebre de Virasoro; leur poids h a la forme h_{p,q}(m)=[ (p(m+1) -qm)^2-1] (4m(m+1)), ou p,q et m sont des entiers positifs et p+q= 2. Ces representations possedent un sous-espace invariant engendre par deux sous-representations avec h_1=h_{p,q} + pq et h_2=h_{p,q} + (m-p)(m+1-q) dont chacun des vecteurs de plus haut poids portent le nom de vecteur singulier et sont notes respectivement |Psi _{p,q}> et |Psi_{m-p,m+1-q}>. . Les theories super-conformes sont une version super-symetrique des theories conformes. Leurs champs appartiennent a des representation de plus haut poids de l'algebre de Neveu-Schwarz, une des deux extensions super -symetriques de l'algebre de Virasoro. Les theories super -conformes minimales possedent la meme structure que les theories conformes minimales. Les representations sont elements de la serie h_{p,q}= [ (p(m+2)-qm)^2-4] /(8m(m+2)) ou p,q et m sont

  19. Etat Des Lieux De La Reglementation Relative A L'homologation ...

    African Journals Online (AJOL)

    Notre étude a comporté d'une part une revue de textes législatifs et réglementaires sur les laits infantiles tant au plan national qu'international et une phase d'enquête transversale dans le district d'Abidjan, auprès des officines privées de pharmacie et des grossistes répartiteurs privés de produits pharmaceutiques.Il ressort ...

  20. Spectrally selective solar energy materials

    International Nuclear Information System (INIS)

    Sikkens, M.

    1981-01-01

    The performance and properties of spectrally selective materials are considered and, in particular, the selective absorption of solar radiation by free electrons is discussed, both in a homogeneous material in which these electrons are strongly scattered, and in a composite material consisting of small metal particles in a dielectric host. Such materials can be used as selective absorbers if they are deposited as a thin film onto a metal substrate, the latter providing the required low emittance. This type of selective surfaces is produced by reactive sputtering of Ni in an Ar/CH 4 gas mixture. This method can yield Ni films with a considerable carbon concentration. The carbon concentration can be varied over a wide range by adjusting the partial methane pressure. The associated experimental techniques are discussed. As the carbon concentration increases, the structure of the films changes from a Ni phase in which carbon is dissolved, via an intermediate Ni 3 C phase into an amorphous carbon phase with a high electrical resistivity in which small nickel particles are embedded. Both mechanisms of selective absorption by free electrons are observed and are found to be well described by rather simple models. The best selectivity is obtained at high carbon concentrations where the films consist of nickel particles in carbon. Depending on the film thickness and the substrate material, the solar absorptance varies between 0.78 and 0.90, while the thermal emittance varies between 0.025 and 0.04. Since the films are found to be stable at 400 0 C in vacuum, it appears that these films are good candidates for application in photothermal solar energy conversion at temperature levels around 200 0 C and higher. (Auth.)

  1. Heat transfer study of a two-phase refrigerant with liquid-solid phase change inside a smooth plates heat exchanger; Etude des transferts de chaleur d'un fluide frigoporteur diphasique a changement de phase liquide-solide dans un echangeur a plaques lisses

    Energy Technology Data Exchange (ETDEWEB)

    Demasles, H.

    2002-05-15

    The purpose of the work is to study two-phase mixture heat exchange composed of water particles suspended in silicone oil circulating in a closed loop. Water, contained in polymer porous matrix, is freezing by successive passages in plane plate heat exchanger. Thermo-hydraulic literature data analysis about these fluids in exchangers shows important blanks in exchange coefficient and pressure drop forecast methods and in experimental data. Experimental results, issued of global energy balance on a test section specifically conceived and made for this study, show doping effect on exchange coefficient. Before phase change, micro-convective effects of rotating particles improve exchange coefficient of 2,3 factor. Supplementary enhancement included between 2 and 16 appeared during phase change. Trial measured discrepancy are certainly induced by bed layer formation due to low flow speed. At the end of particle freezing, when latent heat is not involved anymore in exchange enhancement, important heat transfer reduction is observed. This is attributed to the cooling suspension rheological evolution and the change of flow particle distribution. Modelling results corroborate heat exchange improvement due to phase change: particles act as sources when discharging there latent heat. They stop fluid temperature dropping and enable to keep a high wall temperature gradient. A deepened suspension rheological study is necessary for a better understanding of observed phenomenon, nevertheless these first results show already an important energetic profit brings by particles in range temperature of 0 and -6 deg C. (author)

  2. On spectral pollution

    International Nuclear Information System (INIS)

    Llobet, X.; Appert, K.; Bondeson, A.; Vaclavik, J.

    1990-01-01

    Finite difference and finite element approximations of eigenvalue problems, under certain circumstances exhibit spectral pollution, i.e. the appearance of eigenvalues that do not converge to the correct value when the mesh density is increased. In the present paper this phenomenon is investigated in a homogeneous case by means of discrete dispersion relations: the polluting modes belong to a branch of the dispersion relation that is strongly distorted by the discretization method employed, or to a new, spurious branch. The analysis is applied to finite difference methods and to finite element methods, and some indications about how to avoiding polluting schemes are given. (author) 5 figs., 10 refs

  3. Mechanical spectral shift reactor

    International Nuclear Information System (INIS)

    Doshi, P.K.; George, R.A.; Dollard, W.J.

    1982-01-01

    A mechanical spectral shift arrangement for controlling a nuclear reactor includes a plurality of reactor coolant displacer members which are inserted into a reactor core at the beginning of the core life to reduce the volume of reactor coolant-moderator in the core at start-up. However, as the reactivity of the core declines with fuel depletion, selected displacer members are withdrawn from the core at selected time intervals to increase core moderation at a time when fuel reactivity is declining. (author)

  4. Spectral signatures of chirality

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Mortensen, Asger

    2009-01-01

    We present a new way of measuring chirality, via the spectral shift of photonic band gaps in one-dimensional structures. We derive an explicit mapping of the problem of oblique incidence of circularly polarized light on a chiral one-dimensional photonic crystal with negligible index contrast...... to the formally equivalent problem of linearly polarized light incident on-axis on a non-chiral structure with index contrast. We derive analytical expressions for the first-order shifts of the band gaps for negligible index contrast. These are modified to give good approximations to the band gap shifts also...

  5. Spectral shift reactor

    International Nuclear Information System (INIS)

    Carlson, W.R.; Piplica, E.J.

    1982-01-01

    A spectral shift pressurized water reactor comprising apparatus for inserting and withdrawing water displacer elements having differing neutron absorbing capabilities for selectively changing the water-moderator volume in the core thereby changing the reactivity of the core. The displacer elements comprise substantially hollow cylindrical low neutron absorbing rods and substantially hollow cylindrical thick walled stainless rods. Since the stainless steel displacer rods have greater neutron absorbing capability, they can effect greater reactivity change per rod. However, by arranging fewer stainless steel displacer rods in a cluster, the reactivity worth of the stainless steel displacer rod cluster can be less than a low neutron absorbing displacer rod cluster. (author)

  6. L'accumulation des métaux lourds au niveau des cultures : Cas des ...

    African Journals Online (AJOL)

    Le Bassin de Sebou présente une importance socio-économique pour le Maroc. En effet, il est sujet de diverses utilisations ; eau potable, eau d'irrigation et eau industrielle. Toutefois, ce bassin subit des pressions multiples, notamment par la pollution métallique. Considérant le risque de bioaccumulation des métaux par ...

  7. Study of a three-phase flow metering process for oil-water-gas flows; Etude d`un procede de mesure des debits d`un ecoulement triphasique de type eau-huile-gaz

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, Ch.

    1996-11-01

    We propose a theoretical and experimental study of a three-phase flow metering process for oil-water-gas flows. The selected process is based on a combination of a mixer, a Venturi and ultrasonic methods. To perform an experimental validation of this process an instrumented set-up for three-phase air-oil-water flows has been designed, conceived and adjusted. An original theoretical model have been built to predict three-phase dispersed flows across a contraction. Once validated with two-phase air-water, oil-water and air-oil-water flows data, this model has been used to solve the Venturi metering problems. After a critical review of the available techniques, the ultrasonic propagation velocity has been selected to determine two-phase liquid-liquid flow composition. Two original models have been developed to describe the ultrasonic propagation with the dispersed phase fraction. The comparison with experimental data in oil-water flows show the superiority of one of the two models, the scattering model. For the void fraction determination in air-water flows, the work of Bensler (1990) based on the ultrasonic attenuation measurement has been extended to take into account the multiple scattering effects. Finally these techniques have been combined to determine the different flow rates in air-water, oil-water flows. For two-phase air-water and oil-water flows the problem is solved and the flow rates are measured with a very good accuracy ({+-} 3%). The results quality obtained with three-phase oil-water-gas flows and the secure theoretical bases allowing their interpretation give us the opportunity to strongly recommend the development of an industrial prototype based on the process we studied. (author) 183 refs.

  8. 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)

  9. Spectral Efficiency of OCDMA Systems With Coherent Pulsed Sources

    Science.gov (United States)

    Rochette, Martin; Rusch, Leslie A.

    2005-03-01

    We present a model to evaluate the upper limit of the spectral efficiency of optical code-division multiple-access (OCDMA) systems with coherent sources. Phase-encoded and direct-sequence OCDMA systems are evaluated using this model. The results show that a spectral efficiency of 2.24x10^-2 b/s.Hz can be achieved with a maximum bit error rate of 10^-10 in these systems of the number of users. This result demonstrates that the maximum spectral efficiency of OCDMA systems with coherent sources is at least a factor of 5 higher than OCDMA systems with incoherent sources.

  10. Intensity Conserving Spectral Fitting

    Science.gov (United States)

    Klimchuk, J. A.; Patsourakos, S.; Tripathi, D.

    2015-01-01

    The detailed shapes of spectral line profiles provide valuable information about the emitting plasma, especially when the plasma contains an unresolved mixture of velocities, temperatures, and densities. As a result of finite spectral resolution, the intensity measured by a spectrometer is the average intensity across a wavelength bin of non-zero size. It is assigned to the wavelength position at the center of the bin. However, the actual intensity at that discrete position will be different if the profile is curved, as it invariably is. Standard fitting routines (spline, Gaussian, etc.) do not account for this difference, and this can result in significant errors when making sensitive measurements. Detection of asymmetries in solar coronal emission lines is one example. Removal of line blends is another. We have developed an iterative procedure that corrects for this effect. It can be used with any fitting function, but we employ a cubic spline in a new analysis routine called Intensity Conserving Spline Interpolation (ICSI). As the name implies, it conserves the observed intensity within each wavelength bin, which ordinary fits do not. Given the rapid convergence, speed of computation, and ease of use, we suggest that ICSI be made a standard component of the processing pipeline for spectroscopic data.

  11. Spectral Analysis of Vector Magnetic Field Profiles

    Science.gov (United States)

    Parker, Robert L.; OBrien, Michael S.

    1997-01-01

    We investigate the power spectra and cross spectra derived from the three components of the vector magnetic field measured on a straight horizontal path above a statistically stationary source. All of these spectra, which can be estimated from the recorded time series, are related to a single two-dimensional power spectral density via integrals that run in the across-track direction in the wavenumber domain. Thus the measured spectra must obey a number of strong constraints: for example, the sum of the two power spectral densities of the two horizontal field components equals the power spectral density of the vertical component at every wavenumber and the phase spectrum between the vertical and along-track components is always pi/2. These constraints provide powerful checks on the quality of the measured data; if they are violated, measurement or environmental noise should be suspected. The noise due to errors of orientation has a clear characteristic; both the power and phase spectra of the components differ from those of crustal signals, which makes orientation noise easy to detect and to quantify. The spectra of the crustal signals can be inverted to obtain information about the cross-track structure of the field. We illustrate these ideas using a high-altitude Project Magnet profile flown in the southeastern Pacific Ocean.

  12. Wave Separation. Part Two: Applications La séparation des ondes. Deuxième partie : applications

    Directory of Open Access Journals (Sweden)

    Glangeaud F.

    2006-11-01

    qui doit être de plus grande amplitude. Le filtrage est effectué sans effet de bord et les variations d'amplitude de l'onde sont préservées. Il permet de séparer les données en un espace signal et un espace bruit. Le filtre SMF (matrice spectrale est coûteux en temps de calcul. Il fait l'hypothèse que l'onde est localement stable. Il ne nécessite pas la mise à plat des données. Il permet de séparer des ondes très voisines sans faire appel à des hypothèses a priori fortes. Il donne une mesure des écarts de temps. Il donne une mesure des variations de spectre d'amplitude et de phase lors de la propagation bien supérieure à celle fournie par la méthode de Wiener puisqu'il opère sur l'ensemble des traces. Il permet également de séparer les données en un espace signal et un espace bruit. La méthode paramétrique est la plus coûteuse en temps. Elle est simple à mettre en oeuvre et ne nécessite ni mise à plat ni préparation de données. Elle extrait les ondes en fonction des paramètres retenus, notamment les écarts de temps. Elle est particulièrement recommandée en profil sismique déporté où la lenteur des ondes montantes n'est pas connue. Elle est robuste vis-à-vis de quelques paramètres d'entrée si le bruit est faible par le rapport au signal à extraire. Les multiples applications à des données réelles ont illustré l'efficacité de ces techniques de séparation d'ondes. Par contre, l'application à un nouveau type de données nécessite souvent un contrôle des performances pour choisir la meilleure méthode.

  13. Terre des hommes

    CERN Multimedia

    Staff Association

    2012-01-01

    Transformez votre téléphone portable en geste de solidarité ! Collecte du 12 au 23 novembre 2012   Faites un geste simple et utile en déposant vos téléphones portables inutilisés dans les urnes installées dans les trois restaurants du CERN. En Suisse, une personne change tous les 12 à 18 mois de téléphone portable. La plupart de nos vieux appareils sont simplement laissés à l’abandon avec comme seule fonction de parer une éventuelle panne à venir. On  estime ainsi que 8 millions de portables sont inutilisés, alors qu'entre 30 et 50% peuvent être réutilisés. L'action Solidarcomm leur offre une deuxième vie ! Terre des Hommes Suisse, dans le cadre de la campagne Solidarcomm, collecte et valorise vos téléphones inutilis&...

  14. Onlinespieler abseits des Mainstreams

    Directory of Open Access Journals (Sweden)

    Harald Baumgartlinger

    2012-12-01

    Full Text Available MMO(RPGs „Massively Multiplayer Online (Role-Playing Games“ nehmen einen Sonderstatus unter den Onlinespielen ein, welcher durch den wachsenden wirtschaftlichen Erfolg, insbesondere durch den „breakthrough hit“ (Duchenaut et al. 2006: 407 World of Warcraft (WoW, auch an Bedeutung für die Medien- und Kommunikationswissenschaft gewinnt (vgl. Inderst 2009: 15; vgl. Seifert/Jöckel 2008: 297. Der Primus des Genres, WoW, repräsentiert gemeinsam mit einigen nahezu identen Titeln insgesamt 85 Prozent der gespielten MMOGs (vgl. Williams et al. 2008: 999. Daher befasst sich auch die Mehrheit der vorliegenden Studien mit eben diesen Spielen. Neue Formen von MMO(Gs können jedoch zu ebenso neuartigen Spielerfahrungen führen und damit unterschiedliche Nutzungsmotive befriedigen (vgl. Seifert/Jöckel 2008: 309 und folglich zu einem gänzlich anderen Spielerleben führen. Während im Mainstream die kooperativen Spielerbeziehungen überwiegen, dominiert in Darkfall Online der soziale Wettbewerb. Der von Williams et al. 2008 verwendete Fragebogen diente als Rohling für die Kreation eines für die speziellen Anforderungen adaptierten Erhebungstools zur Erforschung der Spielertypologie und der Motive der Darkfall-Online-SpielerInnen. Die in der Onlinebefragung (N = 506 gesammelten Daten belegen, dass sich sowohl die Spielerdemographie, als auch die Motive der Spieler von den Mainstream MMOs unterscheiden. Zudem konnten realweltliche Eigenschaften der Spieler als signifikante Einflussfaktoren für die Spielzuwendung identifiziert werden.

  15. Gyrodactylidae et Gyrodactylose des Salmonidae

    Directory of Open Access Journals (Sweden)

    MALMBERG G.

    1993-01-01

    Full Text Available Vingt et une espèces de Gyrodactylus de Salmonidae arrangées en six groupes sont présentées. Les observations concernant ces espèces dans les milieux naturels et en pisciculture sont résumées. Sur la base de données générales relatives aux espèces de Gyrodactylus en milieu naturel en Scandinavie et Baltique, les observations biologiques, écologiques et comportementales de G. salaris Malmberg, 1957 et G. derjavini MALMBERG et MALMBERG (1987 des salmonidae sauvages des rivières norvégiennes et suédoises sont présentées. La viviparité unique, la reproduction asexuée et sexuée et le pouvoir de reproduction chez les Gyrodactylus sont développés. La Gyrodactylose à G. salaris est abordée en milieu naturel, dans les rivières norvégiennes et en pisciculture, en Suède et au Danemark. L'étude ultrastructurale des blessures causées par G. salaris ainsi que les résultats expérimentaux sur les espèces norvégiennes et canadiennes sont présentés. La distribution géographique naturelle des Salmonidae, les modifications liées à l'homme et à l'activité économique ainsi que les Salmonidae élevés sont revus. La présence de six groupes d'espèces de Gyrodactylus en Amérique du Nord et Eurasie est discutée en fonction de la distribution géographique des espèces hôtes. Il est souligné qu'une propagation intercontinentale des espèces de Gyrodactylus de Salmonidae a dû être impossible à cause de leur origine limnique d'une part et de la salinité élevée des océans atlantique et pacifique d'autre part. Les exigences micro et macro environnementales des espèces sont discutées dans les conditions naturelles et les variations saisonnières, préférendums et tolérances du parasitisme sont signalés. L'effet des conditions de pisciculture sur les espèces de Gyrocactylus sont discutées : la capacité reproductrice et de propagation ainsi que la spécificité — stricte dans la nature — peuvent être influenc

  16. Model France. Efficiently achieving climate protection targets. Nuclear power phase-out scenario adapted in favour of climate protection; Vorbild Frankreich. Klimaschutzziele effizient erreichen. Ausstiegszenario Kernkraft zugunsten des Klimaschutzes angepasst

    Energy Technology Data Exchange (ETDEWEB)

    Leidinger, Tobias [Luther Rechtsanwaltsgesellschaft, Duesseldorf (Germany)

    2017-12-15

    In Germany - after an abrupt, legally controversial and in some cases unconstitutional phase-out of nuclear power (''at any price'') - the next phase-out of is now being negotiated among new coalition partners. In France, on the other hand, energy and climate protection seem to be in the clear sense of the word: the French nuclear phase-out scenario is clearly being ''stretched out'' in order to achieve the promised climate protection targets. Reason seems to have the upper hand in France: instead of ''black-and-white scenarios'', one prefers to stick to what is in reality feasible and achievable. In reality, the expansion of renewable energies, the regulation of the transport sector and electricity production from nuclear energy are not opposites, but complement each other in the interests of affordable energy and effective climate protection.

  17. Current algebra; Algebre des courants

    Energy Technology Data Exchange (ETDEWEB)

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

    1967-07-01

    The first three chapters of these lecture notes are devoted to generalities concerning current algebra. The weak currents are defined, and their main properties given (V-A hypothesis, conserved vector current, selection rules, partially conserved axial current,...). The SU (3) x SU (3) algebra of Gell-Mann is introduced, and the general properties of the non-leptonic weak Hamiltonian are discussed. Chapters 4 to 9 are devoted to some important applications of the algebra. First one proves the Adler- Weisberger formula, in two different ways, by either the infinite momentum frame, or the near-by singularities method. In the others chapters, the latter method is the only one used. The following topics are successively dealt with: semi leptonic decays of K mesons and hyperons, Kroll- Ruderman theorem, non leptonic decays of K mesons and hyperons ( {delta}I = 1/2 rule), low energy theorems concerning processes with emission (or absorption) of a pion or a photon, super-convergence sum rules, and finally, neutrino reactions. (author) [French] La premiere partie de ce cours (trois premiers chapitres), traite des generalites concernant l'algebre de courants. Apres une definition rapide des courants faibles et un rappel de leurs proprietes (hypothese V-A, conservation du courant vecteur, regles de selection, courant axial partiellement conserve,...), l'on introduit l'algebre de Gell-Mann SU (3) x SU (3), et discute les proprietes generales de l'Hamiltonien faible non leptonique. Les chapitres IV a IX sont consacres a des applications importantes de l'algebre des courants. En premier lieu l'on demontre la formule de Adler et Weisberger, par deux methodes differentes, celle dite du repere de moment infini et celle des singularites proches. Cette derniere est seule utilisee dans la suite. Puis, l'on traite successivement les problemes suivants: desintegrations semi-leptoniques des mesons K et des hyperons, theoreme de Kroll-Ruderman, desintegrations non leptoniques des mesons

  18. Spectral Interferometry with Electron Microscopes

    Science.gov (United States)

    Talebi, Nahid

    2016-01-01

    Interference patterns are not only a defining characteristic of waves, but also have several applications; characterization of coherent processes and holography. Spatial holography with electron waves, has paved the way towards space-resolved characterization of magnetic domains and electrostatic potentials with angstrom spatial resolution. Another impetus in electron microscopy has been introduced by ultrafast electron microscopy which uses pulses of sub-picosecond durations for probing a laser induced excitation of the sample. However, attosecond temporal resolution has not yet been reported, merely due to the statistical distribution of arrival times of electrons at the sample, with respect to the laser time reference. This is however, the very time resolution which will be needed for performing time-frequency analysis. These difficulties are addressed here by proposing a new methodology to improve the synchronization between electron and optical excitations through introducing an efficient electron-driven photon source. We use focused transition radiation of the electron as a pump for the sample. Due to the nature of transition radiation, the process is coherent. This technique allows us to perform spectral interferometry with electron microscopes, with applications in retrieving the phase of electron-induced polarizations and reconstructing dynamics of the induced vector potential. PMID:27649932

  19. Multi-dimensional modeling of gas-liquid two-phase flows. Application to the simulation of ascending bubble flows in vertical ducts; Modelisation multidimensionnelle des ecoulements diphasiques gaz-liquide. Application a la simulation des ecoulements a bulles ascendants en conduite verticale

    Energy Technology Data Exchange (ETDEWEB)

    Morel, Ch

    1997-10-31

    The aim of this thesis is the 3-D modeling and numerical simulation of liquid/gas (water/vapor or water/air) two-phase flows in cooling circuits of nuclear power plants during normal and accidental situations. The development of a multidimensional dual-fluid model encounters two problems: the statistical effects of turbulence and the interface mass, momentum and energy transfers. The models developed in this study were introduced in the 3-D module of the CATHARE code developed by the CEA and the results were compared to experimental results available in the literature. The first chapter describes the equations of the local dual-fluid model for the 3-D description of two-phase flows. Closing relations adapted to dispersed flows with isothermal bubbles and without phase transformation are proposed and focus on the momentum transfer at the interfaces. The theoretical study of turbulence in the liquid phase of a bubble flow is modelled in chapter 2. Chapter 3 deals with the voluminal interface area used in the interface mass, momentum and energy transfers, and chapters 4 and 5 concern the application of the developed models to concrete situations. Chapter 4 describes in details the 3-D module of the CATHARE code while chapter 5 gives a comparison of numerical results obtained using the CATHARE code with other experimental results obtained at EdF. (J.S.) 109 refs.

  20. EFFET DU GETTERING SUR LA LONGUEUR DE DIFFUSION DES PLAQUETTES DE SILICIUM SEMICRISTALLIN "SOPLIN"

    Directory of Open Access Journals (Sweden)

    A MOUHOUB

    2003-06-01

    Full Text Available L’effet des diffusions du phosphore à haute température (T = 900°C sur la longueur de diffusion (Ln des plaquettes de silicium semicristallin SOPLIN (SOlidification by PLanar INterface est déterminé par la mesure de la réponse spectrale de la photopile réalisée sur le matériau traité. L’influence de ces recuits sur les paramètres photovoltaïques est enregistrée dans les caractéristiques courant - tension sous éclairement simulé et la réponse spectrale.

  1. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    pollution. L'objectif du présent travail est l'étude de la qualité des eaux superficielles et souterraines pour évaluer le degré de pollution provenant des lixiviats de la décharge et des cours d'eaux dans lesquels les ..... Les métaux lourds dosés ont montré une pollution métallique des eaux souterraine par rapport à la norme.

  2. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    D'autre part, à cause de la corrélation directe entre l'étendue des inondations et les quantités de poissons et de pâturages fournies par la plaine, il y a eu dégradation des ... aux changements climatiques en zone sahélienne du Cameroun. Un des objectifs de notre étude était de préciser le comportement des agriculteurs ...

  3. Rectangular spectral collocation

    KAUST Repository

    Driscoll, Tobin A.

    2015-02-06

    Boundary conditions in spectral collocation methods are typically imposed by removing some rows of the discretized differential operator and replacing them with others that enforce the required conditions at the boundary. A new approach based upon resampling differentiated polynomials into a lower-degree subspace makes differentiation matrices, and operators built from them, rectangular without any row deletions. Then, boundary and interface conditions can be adjoined to yield a square system. The resulting method is both flexible and robust, and avoids ambiguities that arise when applying the classical row deletion method outside of two-point scalar boundary-value problems. The new method is the basis for ordinary differential equation solutions in Chebfun software, and is demonstrated for a variety of boundary-value, eigenvalue and time-dependent problems.

  4. Spectral evolution of galaxies

    International Nuclear Information System (INIS)

    Rocca-Volmerange, B.

    1989-01-01

    A recent striking event in Observational Cosmology is the discovery of a large population of galaxies at extreme cosmological distances (extended from spectral redshifts ≅ 1 to ≥ 3) corresponding to a lookback time of 80% of the Universe's age. However when galaxies are observed at such remote epochs, their appearances are affected by at least two simultaneous effects which are respectively a cosmological effect and the intrinsic evolution of their stellar populations which appear younger than in our nearby galaxies. The fundamental problem is first to disentangle the respective contributions of these two effects to apparent magnitudes and colors of distant galaxies. Other effects which are likely to modify the appearance of galaxies are amplification by gravitational lensing and interaction with environment will also be considered. (author)

  5. Spectral Line Shapes. Proceedings

    International Nuclear Information System (INIS)

    Zoppi, M.; Ulivi, L.

    1997-01-01

    These proceedings represent papers presented at the 13th International Conference on Spectral Line Shapes which was held in Firenze,Italy from June 16-21, 1996. The topics covered a wide range of subjects emphasizing the physical processes associated with the formation of line profiles: high and low density plasma; atoms and molecules in strong laser fields, Dopple-free and ultra-fine spectroscopy; the line shapes generated by the interaction of neutrals, atoms and molecules, where the relavant quantities are single particle properties, and the interaction-induced spectroscopy. There were 131 papers presented at the conference, out of these, 6 have been abstracted for the Energy Science and Technology database

  6. ATR neutron spectral characterization

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, J.W.; Anderl, R.A.

    1995-11-01

    The Advanced Test Reactor (ATR) at INEL provides intense neutron fields for irradiation-effects testing of reactor material samples, for production of radionuclides used in industrial and medical applications, and for scientific research. Characterization of the neutron environments in the irradiation locations of the ATR has been done by means of neutronics calculations and by means of neutron dosimetry based on the use of neutron activation monitors that are placed in the various irradiation locations. The primary purpose of this report is to present the results of an extensive characterization of several ATR irradiation locations based on neutron dosimetry measurements and on least-squares-adjustment analyses that utilize both neutron dosimetry measurements and neutronics calculations. This report builds upon the previous publications, especially the reference 4 paper. Section 2 provides a brief description of the ATR and it tabulates neutron spectral information for typical irradiation locations, as derived from the more historical neutron dosimetry measurements. Relevant details that pertain to the multigroup neutron spectral characterization are covered in section 3. This discussion includes a presentation on the dosimeter irradiation and analyses and a development of the least-squares adjustment methodology, along with a summary of the results of these analyses. Spectrum-averaged cross sections for neutron monitoring and for displacement-damage prediction in Fe, Cr, and Ni are given in section 4. In addition, section4 includes estimates of damage generation rates for these materials in selected ATR irradiation locations. In section 5, the authors present a brief discussion of the most significant conclusions of this work and comment on its relevance to the present ATR core configuration. Finally, detailed numerical and graphical results for the spectrum-characterization analyses in each irradiation location are provided in the Appendix.

  7. Prise en charge des urgences au service d'accueil des urgences ...

    African Journals Online (AJOL)

    Introduction: La prise en charge des patients dans les services d'accueil des urgences est une des meilleures vitrines d'un système de santé. En Afrique subsaharienne, la gestion des urgences se heurte à des difficultés humaines et matérielles. Le but de ce travail était d'évaluer les difficultés de prise en charge au Service ...

  8. Evaluer des études de gestion des entreprises : combiner des éléments principales avec des éléments pratiques

    NARCIS (Netherlands)

    Pennink, B.J.W.

    2002-01-01

    Evaluer la recherche de gestion demande une combinaison des critères classiques et des critères pratiques. Par cette combinaison il est possible de trouver une réponse cerrecte concernant la validité et l'effet de la recherche. Dans cet article nous allons décrire comment une combinaison des

  9. Perceptions locales de la manifestation des changements ...

    African Journals Online (AJOL)

    SARAH

    . PRPR. ERMA. DC. UD cluster 1 cluster 2. Pauvres. Riches et moyens. Figure 4. Positionnement des classes d'impacts socio-économiques des changements climatiques dans un système d'axes de l'analyse factorielle des ...

  10. Migration transnationale des Vietnamiennes en Asie | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Souvent, cependant, les pays d'origine ne disposent pas des politiques ni des lois ayant force exécutoire qui permettraient d'assurer des pratiques d'embauche ... Women's movements in India are struggling to address problems arising from rapidly changing social relations and vulnerabilities associated with, among other ...

  11. Innovation, apprentissage et cadres institutionnels dans des ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Trois secteurs de transformation des ressources naturelles - ceux des pâtes et ... devrait déboucher sur des recommandations concrètes pour l'élaboration de ... bibliothèque de ressources aideront à améliorer les systèmes d'information et ...

  12. Mechanical disequilibria in two-phase flow models: approaches by relaxation and by a reduced model; Modelisation des desequilibres mecaniques dans les ecoulements diphasiques: approches par relaxation et par modele reduit

    Energy Technology Data Exchange (ETDEWEB)

    Labois, M

    2008-10-15

    This thesis deals with hyperbolic models for the simulation of compressible two-phase flows, to find alternatives to the classical bi-fluid model. We first establish a hierarchy of two-phase flow models, obtained according to equilibrium hypothesis between the physical variables of each phase. The use of Chapman-Enskog expansions enables us to link the different existing models to each other. Moreover, models that take into account small physical unbalances are obtained by means of expansion to the order one. The second part of this thesis focuses on the simulation of flows featuring velocity unbalances and pressure balances, in two different ways. First, a two-velocity two-pressure model is used, where non-instantaneous velocity and pressure relaxations are applied so that a balancing of these variables is obtained. A new one-velocity one-pressure dissipative model is then proposed, where the arising of second-order terms enables us to take into account unbalances between the phase velocities. We develop a numerical method based on a fractional step approach for this model. (author)

  13. Spectral Theory of Chemical Bonding

    National Research Council Canada - National Science Library

    Langhoff, P. W; Boatz, J. A; Hinde, R. J; Sheehy, J. A

    2004-01-01

    .... Wave function antisymmetry in the aggregate atomic spectral-product basis is enforced by unitary transformation performed subsequent to formation of the Hamiltonian matrix, greatly simplifying its construction...

  14. [Review of digital ground object spectral library].

    Science.gov (United States)

    Zhou, Xiao-Hu; Zhou, Ding-Wu

    2009-06-01

    A higher spectral resolution is the main direction of developing remote sensing technology, and it is quite important to set up the digital ground object reflectance spectral database library, one of fundamental research fields in remote sensing application. Remote sensing application has been increasingly relying on ground object spectral characteristics, and quantitative analysis has been developed to a new stage. The present article summarized and systematically introduced the research status quo and development trend of digital ground object reflectance spectral libraries at home and in the world in recent years. Introducing the spectral libraries has been established, including desertification spectral database library, plants spectral database library, geological spectral database library, soil spectral database library, minerals spectral database library, cloud spectral database library, snow spectral database library, the atmosphere spectral database library, rocks spectral database library, water spectral database library, meteorites spectral database library, moon rock spectral database library, and man-made materials spectral database library, mixture spectral database library, volatile compounds spectral database library, and liquids spectral database library. In the process of establishing spectral database libraries, there have been some problems, such as the lack of uniform national spectral database standard and uniform standards for the ground object features as well as the comparability between different databases. In addition, data sharing mechanism can not be carried out, etc. This article also put forward some suggestions on those problems.

  15. Steady-State Two-Phase Flow in Porous Media: Review of Progress in the Development of the DeProF Theory Bridging Pore to Statistical Thermodynamics Scales Écoulement diphasique stationnaire en milieu poreux : revue des avancées sur les développements de la théorie DeProF reliant l’échelle du pore à l’échelle de la thermodynamique

    Directory of Open Access Journals (Sweden)

    Valavanides M.S.

    2012-11-01

    Full Text Available Scope of present article is to present the research efforts (implementing experimental study, theoretical analysis and modeling taken towards the development of a complete theory for steady-state concurrent two-phase flow in porous media (the DeProF theory. The current state of progress is outlined and open problems are addressed. First attempts are traced back in the 1980s with the analysis, description and modeling of phenomena governing two-phase flow in pore scale. Appropriate simulators extending over hundreds and/or thousands of pores (network scale were developed in the following decade (1990s; in parallel, extensive experimental research work identified three prototype/elementary flows comprising the average macroscopic flow, namely connected-oil pathway flow, ganglion dynamics and drop traffic flow and mapped their relative contribution to the macroscopic flow in terms of the process parameters. Efforts to provide a consistent physical rationale to explain the experimental observations, i.e. the map of prototype flow regimes, laid the grounds for developing the DeProF (Decomposition in Prototype Flows theory. Amongst the main results/features of the DeProF theory was the identification of the actual operational and system parameters of the process and the introduction – according to ergodicity principles – of the domain of physically admissible internal flow arrangements of the average macroscopic flow. Use of the respective mechanistic model as a simulation tool (in the 2000s revealed many characteristic properties of the sought process. Important is the existence of optimum operating conditions in the form of a smooth and continuous locus in the domain of the process operational parameters. This characteristic remained in latency within the relative permeability curves, until recently unveiled by the DeProF theory. Research efforts continue in the present (2010s by elaborating appropriate physical considerations based on

  16. Aux origines des Jeux olympiques.

    Directory of Open Access Journals (Sweden)

    Isabelle Debilly

    2005-11-01

    Full Text Available Si les Jo modernes sont régulièrement sous les feux de l’actualité, soit par la répétition temporelle des Olympiades elle-même, soit par les enjeux économiques féroces qui découlent du choix des lieux, ceux de l’Antiquité sont en général cantonnés au domaine scolaire ou universitaire. Néanmoins, ils bénéficient tous les quatre ans d`un éclairage médiatique. L’ouvrage Olympie. La victoire pour les dieux est au croisement des deux domaines. En effet, écrit par un ...

  17. Romagnat – Bois des Goules

    OpenAIRE

    Leguet, Daniel

    2014-01-01

    Lien Atlas (MCC) : http://atlas.patrimoines.culture.fr/atlas/trunk/index.php?ap_theme=DOM_2.01.02&ap_bbox=3.027;45.698;3.133;45.745 La parcelle prospectée se situe sur le flanc nord du col des Goules, passage traditionnel vers l’oppidum de Gergovie, dans un profond thalweg emprunté jadis par un chemin descendant sur Romagnat. Sur la pente actuelle entièrement boisée, on trouve des sentiers récents et des pistes de motocross. C’est sur l’une de ces dernières que nous avions recueilli un poids ...

  18. Spectral information (gas, liquid and solid phase from EUV-VUV-UV-Vis-NIR) and related data (e.g. information concerning publications on quantum yield studies or photolysis studies) from published papers

    Science.gov (United States)

    Noelle, A.; Hartmann, G. K.; Martin-Torres, F. J.

    2010-05-01

    The science-softCon "UV/Vis+ Spectra Data Base" is a non-profit project established in August 2000 and is operated in accordance to the "Open Access" definitions and regulations of the CSPR Assessment Panel on Scientific Data and Information (International Council for Science, 2004, HYPERLINK "http://www.science-softcon.de/spectra/cspr.pdf" ICSU Report of the CSPR Assessment Panel on Data and Information; ISBN 0-930357-60-4). The on-line database contains currently about 5600 spectra (from low to very high resolution, at different temperatures and pressures) and datasheets (metadata) of about 850 substances. Additional spectra/datasheets will be added continuously. In addition more than 250 links to on-line free available original publications are provided. The interdisciplinary of this photochemistry database provides a good interaction between different research areas. So, this database is an excellent tool for scientists who investigate on different fields such as atmospheric chemistry, astrophysics, agriculture, analytical chemistry, environmental chemistry, medicine, remote sensing, etc. To ensure the high quality standard of the fast growing UV/Vis+ Spectra Data Base an international "Scientific Advisory Group" (SAG) has been established in 2004. Because of the importance of maintenance of the database the support of the scientific community is crucial. Therefore we would like to encourage all scientists to support this data compilation project thru the provision of new or missing spectral data and information.

  19. Contribution to the study of the thermal and hydrodynamical properties of a two-phase natural circulation flow of normal helium (He I) for the cooling of superconducting magnets; Contribution a l'etude des proprietes thermiques et hydrodynamiques d'un ecoulement d'helium normal (He I) diphasique en circulation naturelle pour le refroidissement des aimants supraconducteurs

    Energy Technology Data Exchange (ETDEWEB)

    Benkheira, L

    2007-06-15

    The method of cooling based on the thermosyphon principle is of great interest because of its simplicity, its passivity and its low cost. It is adopted to cool down to 4,5 K the superconducting magnet of the CMS particles detector of the Large Hadron Collider (LHC) experiment under construction at CERN, Geneva. This work studies heat and mass transfer characteristics of two phase He I in a natural circulation loop. The experimental set-up consists of a thermosyphon single branch loop mainly composed of a phase separator, a downward tube, and a test section. The experiments were conducted with varying several parameters such as the diameter of the test section (10 mm or 14 mm) and the applied heat flux up to the appearance of the boiling crisis. These experiments have permitted to determine the laws of evolution of the various parameters characterizing the flow (circulation mass flow rate, vapour mass flow rate, vapour quality, friction coefficient, two phase heat transfer coefficient and the critical heat flux) as a function of the applied heat flux. On the base of the obtained results, we discuss the validity of the various existing models in the literature. We show that the homogeneous model is the best model to predict the hydrodynamical properties of this type of flow in the vapour quality range 0{<=}x{<=}30%. Moreover, we propose two models for the prediction of the two phase heat transfer coefficient and the density of the critical heat flux. The first one considers that the effects of the forced convection and nucleate boiling act simultaneously and contribute to heat transfer. The second one correlates the measured critical heat flux density with the ratio altitude to diameter. (author)

  20. Problems Associated with the Monochromatisation of Slow Neutrons; Quelques aspects de la monochromatisation des neutrons thermiques; Nekotorye voprosy monokhromatizatsii medlennykh nejtronov; Algunos problemas de la monocromatizacion de neutrones lentos

    Energy Technology Data Exchange (ETDEWEB)

    Vertebnyj, V P; Kolotyj, V V; Majstrenko, A N

    1963-01-15

    The paper sets out the result of calculations to determine the shape of the spectral line of twin-rotor, pulsing, slow-neutron monochromators, as a function of the shifts in the phases between the rotors. Consideration is also given to die possibility of using certain light elements as slow-neutron filters. (author) [French] Les auteurs exposent les resultats de leurs calculs relatifs a la forme du spectre des monochromateurs a impulsions et a deux rotors pour neutrons thermiques en fonction de la distance et du dephasage entre les rotors. Ils examinent egalement la possibilite d*utiliser certains elements legers comme filtres a neutrons lents. (author) [Spanish] Los autores exponen ios resultadas de sus calculos relativos a la forma de la linea espectral de los monocromadores pulsantes de dos rotores para neutrones lentos en funcion de la distancia y del desias amiento de los rotores. Examinan asimismo la posibilidad de utilizar algunos elementos ligeros como filtros de neutrones lentos. (author)

  1. Cardiotoxicité des psychotropes

    OpenAIRE

    TAHIRI, Abdallah

    2013-01-01

    Même à dose thérapeutique, les médicaments psychotropes sont susceptibles d'engendrer des troubles du rythme cardiaque graves avec risque létal concourant à expliquer la pré valence de la mort subite dans la population psychiatrique. Les situations cliniques à risque telles que poly médication (des psychotropes entre eux ou d'un psychotrope avec un non psychotrope allongeur de QTc), interactions médicamenteuses aussi bien pharmacodynamiques que pharmacocinétiques, traitement pa...

  2. Tombes et cimetières éthiopiens : des rois, des saints, des anonymes1

    OpenAIRE

    Derat, Marie-Laure

    2009-01-01

    L’histoire des tombes et cimetières éthiopiens, dans la longue durée, en est encore à ses balbutiements. Si les tombes des saints et des rois nous sont un peu mieux connus grâce à des textes témoignant à la fois des enjeux entourant les sépultures de ces personnages hors du commun et des soins apportés à leur inhumation, en revanche, les cimetières ordinaires échappent encore largement à l’enquête, en grande partie parce que le commun des mortels est inhumé dans l’anonymat et dans un grand dé...

  3. L'intégration des accélérateurs du CERN

    CERN Document Server

    Chemli, S; CERN. Geneva. TS Department

    2008-01-01

    L?intégration du LHC a ouvert des perspectives pour une gestion plus complète des accélérateurs du CERN. La base de données LAYOUT a permis d'assurer la continuité des phases de définition optique du projet, d'intégration 3D et de contrôles de conformité des installations. Les scans et modélisations 3D en couches des installations réalisées constituent un outil déterminant pour la préparation des interventions dans le cadre des procédures de sécurité ALARA. Il est proposé de reproduire cette méthodologie pour les nouveaux projets comme pour les accélérateurs existants. La mise à jour de l'anneau SPS dans LAYOUT semble être la priorité. La base de données SURVEY contient déjà une vue d'ensemble des accélérateurs, chaque composant étant référencé dans le Système de Coordonnées du CERN, selon les définitions théoriques "sources" au 1/100 mm. Base pour l'alignement, elle stocke également les positions réelles des machines. Elle complète ainsi l'information linéaire de LAY...

  4. Traits morphologiques des graines et vigueur des jeunes plants de ...

    African Journals Online (AJOL)

    écologique du Sénégal afin de pouvoir sélectionner une meilleure semence qui sera destinée aux programmes de développement des énergies renouvelables. Morphological traits of seeds and seedling vigor of two sources of Jatropha curcas L. in ...

  5. Traits morphologiques des graines et vigueur des jeunes plants de ...

    African Journals Online (AJOL)

    SARAH

    écologique du Sénégal afin de pouvoir sélectionner une meilleure semence qui sera destinée aux programmes de développement des énergies renouvelables. Journal of Applied Biosciences 88:8249– 8255. ISSN 1997–5902 ...

  6. Original Paper Dynamique des peuplements des Parcelles d'Essais ...

    African Journals Online (AJOL)

    permanentes (PFTP) à Bensékou visait à évaluer la dynamique de la population de ... est alors important de mettre en œuvre une sensibilisation de la population locale sur les mérites de la gestion ..... contrôle des PES se sont encore montré.

  7. Evaluation des conditions de germination des noyaux de Grewia ...

    African Journals Online (AJOL)

    personnel

    31 janv. 2014 ... 1Laboratoire de Physiologie et Production Végétales, Université Marien NGOUABI,. Faculté des Sciences et Techniques, BP.69. Brazzaville, Republique du Congo. 2Ecole Nationale Supérieure d'Agronomie et Forestérie, Université Marien NGOUABI,. BP. 69. Brazzaville, Republique du Congo.

  8. Comparaison des modes de résolution de méthodes d'optimisation et d'invention

    OpenAIRE

    Rasovska , Ivana; Dubois , Sébastien; De Guio , Roland

    2009-01-01

    Dans la résolution des problèmes de conception, l'idée de proposer un modèle unifié de représentation des problèmes pour être utilisé à la fois par les approches d'optimisation et d'invention se révèle très prometteuse. Les deux approches sont en effet complémentaires et l'évolution des systèmes techniques passe par des phases successives d'optimisation et d'invention. Dans un article précédent, les parallèles entre les modèles de représentation des problèmes ont été établis. L'objectif de ce...

  9. Biodiesel production from ethanolysis of palm oil using deep eutectic solvent (DES) as co-solvent

    Science.gov (United States)

    Manurung, R.; Winarta, A.; Taslim; Indra, L.

    2017-06-01

    Biodiesel produced from ethanolysis is more renewable and have better properties (higher oxidation stability, lower cloud and pour point) compared to methanolysis, but it has a disadvantage such as complicated purification. To improve ethanolysis process, deep eutectic solvent (DES) can be prepared from choline chloride and glycerol and used as co-solvent in ethanolysis. The deep eutectic solvent is formed from a quaternary ammonium salt (choline chloride) and a hydrogen bond donor (Glycerol), it is a non-toxic, biodegradable solvent compared to a conventional volatile organic solvent such as hexane. The deep eutectic solvent is prepared by mixing choline chloride and glycerol with molar ratio 1:2 at temperature 80 °C, stirring speed 300 rpm for 1 hour. The DES is characterized by its density and viscosity. The ethanolysis is performed at a reaction temperature of 70 °C, ethanol to oil molar ratio of 9:1, potassium hydroxide as catalyst concentration of 1.2 wt. DES as co-solvent with concentration 0.5 to 3 wt. stirring speed 400 rpm, and a reaction time 1 hour. The obtained biodiesel is then characterized by its density, viscosity, and ester content. The oil - ethanol phase condition is observed in the reaction tube. The oil - ethanol phase with DES tends to form meniscus compared to without DES, showed that oil and ethanol become more slightly miscible, which favors the reaction. Using DES as co-solvent in ethanolysis showed increasing in yield and easier purification. The esters properties meet the international standards ASTM D6751, with the highest yield achieved 83,67 with 99,77 conversion at DES concentration 2 . Increasing DES concentration above 2 in ethanolysis decrease the conversion and yield, because of the excessive glycerol in the systems makes the reaction equilibrium moves to the reactant side.

  10. The structure of para-toluidine by X-ray and neutron diffraction; Etude de la structure de la para-toluidine par la diffraction des rayons X et des neutrons

    Energy Technology Data Exchange (ETDEWEB)

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

    1965-12-01

    The crystal and molecular structure of para-toluidine has been solved by X-ray and neutron diffraction counter techniques. The molecules are arranged in the form of infinite chains in the crystal, each molecule being linked to two neighbours by hydrogen bonds. The presence of the H bonds makes clear the difference in the melting points between para-toluidine and benzene hydrocarbons of related symmetry and molecular weight. Their direction accounts for the (001) cleavage and the growth anisotropy of crystals from supersaturated vapour phase. A structure-seeking method by computer has been elaborated, using lattice energy calculations applied to molecules treated as rigid bodies and making use of a simplex method for function minimization without calculation of derivatives. The way the available information is handled allows to increase the range of convergence, as shown in the case of para-toluidine. (author) [French] La structure cristalline et moleculaire de la para-toluidine a ete resolue a l'aide de la diffraction des rayons X et des neutrons. L'analyse a revele que la structure presentait un encha ement particulier des molecules, liees entre elles par des ponts hydrogene. La presence des liaisons rend compte de l'elevation du point de fusion de la para-toluidine par rapport a celui des carbures benzeniques de symetrie et de poids moleculaires voisins. La direction des liaisons explique le clivage facile (001) des cristaux obtenus par fusion et l'anisotropie de croissance des cristaux en phase vapeur. Une methode de recherche de structures par ordinateur a ete elaboree, faisant usage du concept d'energie reticulaire applique aux molecules considerees comme rigides et faisant appel a une methode de simplexe pour la minimisation des fonctions sans calcul de derivees. La maniere dont est exploitee l'information disponible permet d'accro re, comme cela est montre dans le cas de la para-toluidine, l'etendue du domaine de convergence. (auteur)

  11. Modelling and numerical simulation of two-phase flows using the two-fluid two-pressure approach; Modelisation et simulation numerique des ecoulements diphasiques par une approche bifluide a deux pressions

    Energy Technology Data Exchange (ETDEWEB)

    Guillemaud, V

    2007-03-15

    This thesis is devoted to the modelling and numerical simulation of liquid-vapor flows. In order to describe these phase transition flows, a two-fluid two-pressure approach is considered. This description of the liquid-vapor mixing is associated to the seven-equation model introduced by Baer and Nunziato. This work investigates the properties of this model in order to simulate the phase transition flows occurring in nuclear engineering. First, a theoretical thermodynamic framework is constructed to describe the liquid-vapor mixing. Provided with this framework, various modelling choices are suggested for the interaction terms between the phases. These closure laws comply with an entropy inequality. The mathematical properties of this model are thereafter examined. The convective part is associated to a nonconservative hyperbolic system. First, we focus on the definition of its weak solutions. Several flow regimes for the two-phase mixing derive from this analysis. Such regimes for the two-phase flows are analogous to the torrential and fluvial regimes for the shallow-water equations. Furthermore, we establish the linear and nonlinear stabilities of the liquid-vapor equilibrium. Finally, the implementation of a turbulence model and the introduction of a reconstruction process for the interfacial area are investigated in order to refine the description of the interfacial transfers. Using a fractional step approach, a Finite Volume method is at last constructed to simulate this model. First, various nonconservative adaptations of standard Riemann solvers are developed to approach the convective part. Unlike the classic nonconservative framework, these schemes converge towards the same solution. Furthermore, a new relaxation scheme is proposed to approach the interfacial transfers. Provided with these schemes, the whole numerical method preserves the liquid-vapor equilibria. Using this numerical method, a careful comparison between the one- and two-pressure two

  12. Optical spectral weight anomalies and strong correlation

    International Nuclear Information System (INIS)

    Toschi, A.; Capone, M.; Ortolani, M.; Calvani, P.; Lupi, S.; Castellani, C.

    2007-01-01

    The anomalous behavior observed in the optical spectral weight (W) of the cuprates provides valuable information about the physics of these compounds. Both the doping and the temperature dependences of W are hardly explained through conventional estimates based on the f-sum rule. By computing the optical conductivity of the doped Hubbard model with the Dynamical Mean Field Theory, we point out that the strong correlation plays a key role in determining the basic features of the observed anomalies: the proximity to a Mott insulating phase accounts simultaneously for the strong temperature dependence of W and for its zero temperature value

  13. Experimental investigation of smoothing by spectral dispersion

    International Nuclear Information System (INIS)

    Regan, Sean P.; Marozas, John A.; Kelly, John H.; Boehly, Thomas R.; Donaldson, William R.; Jaanimagi, Paul A.; Keck, Robert L.; Kessler, Terrance J.; Meyerhofer, David D.; Seka, Wolf

    2000-01-01

    Measurements of smoothing rates for smoothing by spectral dispersion (SSD) of high-power, solid-state laser beams used for inertial confinement fusion (ICF) research are reported. Smoothing rates were obtained from the intensity distributions of equivalent target plane images for laser pulses of varying duration. Simulations of the experimental data with the known properties of the phase plates and the frequency modulators are in good agreement with the experimental data. These results inspire confidence in extrapolating to higher bandwidths and other SSD configurations that may be suitable for ICF experiments and ultimately for direct-drive laser-fusion ignition. (c) 2000 Optical Society of America

  14. SPECTRAL ANALYSIS OF EXCHANGE RATES

    Directory of Open Access Journals (Sweden)

    ALEŠA LOTRIČ DOLINAR

    2013-06-01

    Full Text Available Using spectral analysis is very common in technical areas but rather unusual in economics and finance, where ARIMA and GARCH modeling are much more in use. To show that spectral analysis can be useful in determining hidden periodic components for high-frequency finance data as well, we use the example of foreign exchange rates

  15. La maison des mathématiques

    CERN Document Server

    Villani, Cédric; Moncorgé, Vincent

    2014-01-01

    Comment travaillent les mathématiciens ? C'est peut-être en se promenant dans les couloirs de la première des " maisons des mathématiques " de France, l'institut Henri Poincaré, que l'on trouvera quelques réponses. Le mathématicien Cédric Villani et le physicien Jean-Philippe Uzan nous invitent à découvrir cette discipline et ses acteurs. Au fil des pages on suit, à travers de superbes images signées du photographe Vincent Moncorgé, la façon dont se fabrique cette science qui reste souvent mystérieuse. Toutes les dimensions, scientifique, esthétique et poétique, des mathématiques sont convoquées grâce à des regards croisés : la diversité des inspirations des chercheurs, la source de leur créativité, l'imaginaire littéraire et artistique des mathématiques, la drôle de tribu des mathématiciens. Un voyage au cœur de cette " auberge espagnole " des mathématiques, campus " à la française " accueillant des centaines de chercheurs du monde entier, devenu un lieu d'émulation et d'éc...

  16. Etude des erreurs d'estimation des populations par la méthode des captures successives (DeLURY, 2 captures et des captures-recaptures (PETERSEN

    Directory of Open Access Journals (Sweden)

    LAURENT M.

    1978-01-01

    Full Text Available L'estimation des populations naturelles par capture-recapture et par captures successives est souvent entachée d'erreur car, dans de nombreux cas, l'hypothèse fondamentale d'égalité des probabilités de captures pour tous les individus dans le temps et dans l'espace n'est pas respectée. Dans le cas des populations de poissons envisagés ici, les captures ont lieu par la pêche électrique. On a pu chiffrer l'ordre de grandeur des erreurs systématiques faites sur l'estimation des peuplements, en fonction des conditions particulières, biotiques et abiotiques, des différents milieux inventoriés.

  17. ULTRAVIOLET RAMAN SPECTRAL SIGNATURE ACQUISITION: UV RAMAN SPECTRAL FINGERPRINTS.

    Energy Technology Data Exchange (ETDEWEB)

    SEDLACEK,III, A.J.FINFROCK,C.

    2002-09-01

    As a member of the science-support part of the ITT-lead LISA development program, BNL is tasked with the acquisition of UV Raman spectral fingerprints and associated scattering cross-sections for those chemicals-of-interest to the program's sponsor. In support of this role, the present report contains the first installment of UV Raman spectral fingerprint data on the initial subset of chemicals. Because of the unique nature associated with the acquisition of spectral fingerprints for use in spectral pattern matching algorithms (i.e., CLS, PLS, ANN) great care has been undertaken to maximize the signal-to-noise and to minimize unnecessary spectral subtractions, in an effort to provide the highest quality spectral fingerprints. This report is divided into 4 sections. The first is an Experimental section that outlines how the Raman spectra are performed. This is then followed by a section on Sample Handling. Following this, the spectral fingerprints are presented in the Results section where the data reduction process is outlined. Finally, a Photographs section is included.

  18. The Reactions of Hot Fluorine-18 with Gaseous Carbon Tetrafluoride; Reactions des Atomes {sup 18}F Chauds avec le Tetrafluorure de Carbone en Phase Gazeuse; Reaktsii goryachikh atomov ftora-18 s gazovoj fazoj tetraftormetana; Reacciones de Atomos Calientes de Fluor-18 con Tetrafluoruro de Carbono Gaseoso

    Energy Technology Data Exchange (ETDEWEB)

    Colebourne, N.; Todd, J. F.J.; Wolfgang, R. [Yale University, New Haven, CT (United States)

    1965-04-15

    'electrons de l'Universite Yale. Le processus {sup 19}F ({gamma}, n){sup 18}F donne des atomes de {sup 18}F d'une energie cinetique de l'ordre de 10{sup 5} a 10{sup 6} eV. Ces especes perdent de l'energie par choc et doivent atteindre la gamme des energies 'chimiques' (< 100 eV) en tant qu'atomes a l'etat fondamental. Les auteurs ont constate que Vethylene etait un excellent agent de balayage pour les atomes {sup 18}F thermiques. Ils ont analyse les produits a l'aide de methodes courantes de radiochromatographie en phase gazeuse. Le systeme s'est revele tres sensible aux effets de rayonnements etrangers; aussi les mesures de precaution appropriees ont-elles ete prises. Des reactions de deplacement, analbgues a celles qui ont ete observees pour l'hydrogene chaud mais beaucoup moins efficaces, ont ete relevees; ce sont les reactions suivantes: {sup 18}F + {sup 4}CF --> CF{sub 3}{sup 18}F + F, {sup 18}F + CF{sub 4} --> CF{sub 2}{sup 18}F + (F + F), Il n'a pas ete possible d'etudier directement la reaction d'enlevement {sup 18}F + CF{sub 4} --> CF{sub 3} + F{sup 18}F. Cependant, certains indices donnent a penser que cette reaction a egalement une faible efficacite. Les auteurs ont etudie en detail l'effet de ralentissement sur le systeme {sup 18}F + CF{sub 4}. Ils ont analyse les donnees obtenues en se fondant sur la theorie cinetique des reactions chaudes. Ils ont constate que le systeme etait conforme a cette theorie, ce qui a fourni une confirmation quantitative de l'interpretation actuelle des resultats. Les systemes methane et tetrafluorure de carbone fournissent une base a certaines conclusions provisoires sur les mecanismes des reactions des atomes de fluor chauds. Il semble a present que, moyennant certaines modifications importantes mais naturelles, le modele qui avait tout d'abord ete mis au point pour les atomes d'hydrogene chauds soit applicable aux atomes de fluor chauds. (author) [Spanish] La memoria describe estudios de las reacciones de atomos calientes de {sup 18}F

  19. Reduction des effectifs ou licenciements

    CERN Multimedia

    Maiani, Luciano

    2002-01-01

    "Vous faites un amalgame entre la reduction en cours des effectifs du CERN (organisation europeenne pour la recherche nucleaire) et les economies que le laboratoire doit realiser dans les cinq ans a venir pour financer le projet de grand collisionneur de hadrons (Le Monde du 4 septembre)" (1/2 page).

  20. Les parcs des porcelainiers Haviland

    Directory of Open Access Journals (Sweden)

    Colette Chabrely

    2012-04-01

    Full Text Available Les parcs du Reynou et de Mont-Méry en Limousin, anciennes propriétés des porcelainiers Haviland, présentent l’un et l’autre un grand intérêt paysager et botanique. Dans les deux cas, l’attribution de la création est incertaine. Cet article propose pour le Reynou une analyse de documents figurés anciens permettant de préciser la chronologie des travaux du château et du parc. Pour Mont-Méry il s’agit de poser de nouveaux jalons pour une étude plus approfondie des sources et de la composition des jardins afin d’envisager de nouvelles pistes pour leur attribution.The Reynou and Mont-Méry parks near Limoges originally belonged to the city’s porcelain manufacturers, the Havilands. Both parks are of considerable interest in terms of their landscaping and their botany. In both cases, there is some uncertainty as to the identity of their designers. This article offers an analysis of the graphic representations of the Reynou park, clarifying the chronology of the creation of the château and its park. For the Mont-Méry park, the aim is to offer some guidelines for further research in the source material and on the design of the park itself, perhaps allowing for the designer to be identified.

  1. Bangalore, ville des nouvelles technologies

    Directory of Open Access Journals (Sweden)

    Clarisse Didelon

    2003-06-01

    Full Text Available Bangalore est devenue la Silicon Valley de l’Inde. Une partie de ses habitants y vit à l’occidentale mais le reste de la population souffre de la croissance spectaculaire de la ville. Face à l’insuffisance des infrastructures, Bangalore devient de moins en moins attractive pour les entreprises internationales.

  2. Dimensioning of a two-phase loop for the study of the cooling of power electronics components; Dimensionnement d`une boucle diphasique pour l`etude du refroidissement des composants d`electronique de puissance

    Energy Technology Data Exchange (ETDEWEB)

    Bricard, A [CEA Centre d` Etudes Nucleaires de Grenoble, 38 (France). STTGRETh

    1997-12-31

    After having chosen between different cooling solutions for a given power electronics component, the dimensioning of a two-phase forced convection loop is described. The power electronics component is a 12 x 12 mm silicon pellet which can dissipate up to 400 W/cm{sup 2} heat fluxes. In a first step, the minimum size of channels is determined according to fluid characteristics, pressure drop and critical fluxes. In a second step, the coupled dimensioning of both the evaporator and the condenser is determined for different values of pipes diameter and mass flow rates. (J.S.) 8 refs.

  3. Dimensioning of a two-phase loop for the study of the cooling of power electronics components; Dimensionnement d`une boucle diphasique pour l`etude du refroidissement des composants d`electronique de puissance

    Energy Technology Data Exchange (ETDEWEB)

    Bricard, A. [CEA Centre d`Etudes Nucleaires de Grenoble, 38 (France). STTGRETh

    1996-12-31

    After having chosen between different cooling solutions for a given power electronics component, the dimensioning of a two-phase forced convection loop is described. The power electronics component is a 12 x 12 mm silicon pellet which can dissipate up to 400 W/cm{sup 2} heat fluxes. In a first step, the minimum size of channels is determined according to fluid characteristics, pressure drop and critical fluxes. In a second step, the coupled dimensioning of both the evaporator and the condenser is determined for different values of pipes diameter and mass flow rates. (J.S.) 8 refs.

  4. Évaluation de la valeur nutritive et recherche des substances ...

    African Journals Online (AJOL)

    SARAH

    30 juin 2016 ... et des lipides. Puis, l'évaluation a été effectuée sur ces échantillons pour rechercher la présence des alcaloïdes, des saponines, des quinones, des stéroïdes, des terpenoïdes, des flavonoïdes, des leucoanthocyanes, des tannoïdes et des hétérosides cyanogénétiques. Les teneurs moyennes en humidité ...

  5. Fatigue of the quenched and hardened steel 42CrMo4 under multiaxial in- and out-of-phase loading; Ermuedung des Stahles 42CrMo4 unter mehrachsiger, phasenverschobener Beanspruchung

    Energy Technology Data Exchange (ETDEWEB)

    Loewisch, G. [Stiftung Inst. fuer Werkstofftechnik, Bremen (Germany); Bomas, H.; Mayr, P.

    1999-10-01

    Two kinds of specimens out of the quenched and hardened steel 42CrMo4 (similar SAE 4140) were tested by combined tension-torsion in- and out-of-phase loading. The specimens batches differed in the residual stress state. Under cyclic, stress controlled loading an elastic behaviour is registrated until 50% of the life time. Then a rapid softening occurs, which correlates with the von-Mises equivalent stress in the case of in-phase loading. At high stress amplitudes, the residual stresses may be neglected. The lifetime is best described by the fatigue criterion of Zenner which considers the integral average of the stress state in every plane. This stress state is described by a linear combination of the shear stress amplitude and the normal stress amplitude. Below the cyclic yield strength, the residual stresses must be taken into account as static stresses. The comparison of the local residual stress distributions is possible by using the weakest link model of Heckel, which is described in detail. (orig.)

  6. Osteoporose und Genetik des Knochenstoffwechsels

    Directory of Open Access Journals (Sweden)

    Obermayer-Pietsch B

    2002-01-01

    Full Text Available Osteoporose ist in hohem Maß genetisch determiniert. Neue Wege der molekularbiologischen Forschung haben sich in den letzten Jahren auf diesem Gebiet etabliert. "Gene mapping" mit polymorphen genetischen Markern auf der Suche nach Phänotyp-assoziierten Genen ist ein aufwendiges, aber vielversprechendes Verfahren und wird durch die Erkenntnisse des Human Genome Projects beschleunigt. So wurde jüngst u. a. das Low-density Lipoprotein 5-Gen als wichtig für den Knochenstoffwechsel identifiziert. Kandidaten-gene wie Hormonrezeptor-, Cytokin- oder Kollagen-Gene werden hinsichtlich ihrer Gen-Gen- und Gen-Umwelt- Interaktionen untersucht und erlauben neue funktionelle Einsichten in Erkrankungen des Knochenstoffwechsels. Mutationen der Kollagen-Gene sind bei einigen seltenen Erkrankungen, wie dem Osteoporose-Pseudogliom-Syndrom oder der Osteogenesis imperfecta gefunden worden, könnten aber auch für häufige Varianten von Bindegewebsstörungen wie der congenitalen Hüftdysplasie verantwortlich sein, die etwa 10 % der weiblichen kaukasischen Bevölkerung in unterschiedlichem Ausmaß betrifft. Osteoporose am Schenkelhals und erhöhte Gelenkslaxizität sowie andere generalisierte Veränderungen des Knochen- und Kollagenstoffwechsels können hier möglicherweise ebenfalls durch Störungen des Kollagen I alpha 1-Gens erklärt werden. In Summe können wir zahlreiche neue Einsichten in die Pathophysiologie des Skelettsystems erwarten, die uns auch neue Zugangswege für Diagnostik und Therapie unserer Patienten ermöglichen werden.

  7. L'astronomie des Anciens

    Science.gov (United States)

    Nazé, Yaël

    2009-04-01

    Quelle que soit la civilisation à laquelle il appartient, l'être humain cherche dans le ciel des réponses aux questions qu'il se pose sur son origine, son avenir et sa finalité. Le premier mérite de ce livre est de nous rappeler que l'astronomie a commencé ainsi à travers les mythes célestes imaginés par les Anciens pour expliquer l'ordre du monde et la place qu'ils y occupaient. Mais les savoirs astronomiques passés étaient loin d'être négligeables et certainement pas limités aux seuls travaux des Grecs : c'est ce que l'auteur montre à travers une passionnante enquête, de Stonehenge à Gizeh en passant par Pékin et Mexico, fondée sur l'étude des monuments anciens et des sources écrites encore accessibles. Les tablettes mésopotamiennes, les annales chinoises, les chroniques médiévales, etc. sont en outre d'une singulière utilité pour les astronomes modernes : comment sinon remonter aux variations de la durée du jour au cours des siècles, ou percer la nature de l'explosion qui a frappé tant d'observateurs en 1054 ? Ce livre offre un voyage magnifiquement illustré à travers les âges, entre astronomie et archéologie.

  8. Concept for urban heating systems using co-generation; Conception de systemes de chauffage urbain pour la cogeneration. Phase I: application au quartier des Morasses (Martigny) de la methode de conception des reseaux de chauffage urbain developpe au LENI. Rapport final

    Energy Technology Data Exchange (ETDEWEB)

    Cherix, G. [Centre de competence en urbistique CREM, Martigny (Switzerland); Weber, C. [Swiss Federal Institute of Technology (EPFL), Laboratoire d' energetique industrielle (LENI), Lausanne (Switzerland)

    2006-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) reviews the work done in the first phase of a project concerning the concept for a district heating system in Martigny, Switzerland. This work was carried out by the Centre for Municipal and Energy Research CREM in Martigny, Switzerland, and the Laboratory for Industrial Energy LENI at the Swiss Federal Institute of Technology in Lausanne. Software developed at the LENI is introduced and its use for the determination of the necessary configuration and modes of operation of a district heating system in Martigny is discussed. The situation in the Morasses district of Martigny and the promising results obtained are looked at. These can lead to the optimisation of heating supply in other such areas.

  9. Ultraviolet spectral reflectance of carbonaceous materials

    Science.gov (United States)

    Applin, Daniel M.; Izawa, Matthew R. M.; Cloutis, Edward A.; Gillis-Davis, Jeffrey J.; Pitman, Karly M.; Roush, Ted L.; Hendrix, Amanda R.; Lucey, Paul G.

    2018-06-01

    A number of planetary spacecraft missions have carried instruments with sensors covering the ultraviolet (UV) wavelength range. However, there exists a general lack of relevant UV reflectance laboratory data to compare against these planetary surface remote sensing observations in order to make confident material identifications. To address this need, we have systematically analyzed reflectance spectra of carbonaceous materials in the 200-500 nm spectral range, and found spectral-compositional-structural relationships that suggest this wavelength region could distinguish between otherwise difficult-to-identify carbon phases. In particular (and by analogy with the infrared spectral region), large changes over short wavelength intervals in the refractive indices associated with the trigonal sp2π-π* transition of carbon can lead to Fresnel peaks and Christiansen-like features in reflectance. Previous studies extending to shorter wavelengths also show that anomalous dispersion caused by the σ-σ* transition associated with both the trigonal sp2 and tetrahedral sp3 sites causes these features below λ = 200 nm. The peak wavelength positions and shapes of π-π* and σ-σ* features contain information on sp3/sp2, structure, crystallinity, and powder grain size. A brief comparison with existing observational data indicates that the carbon fraction of the surface of Mercury is likely amorphous and submicroscopic, as is that on the surface of the martian satellites Phobos and Deimos, and possibly comet 67P/Churyumov-Gerasimenko, while further coordinated observations and laboratory experiments should refine these feature assignments and compositional hypotheses. The new laboratory diffuse reflectance data reported here provide an important new resource for interpreting UV reflectance measurements from planetary surfaces throughout the solar system, and confirm that the UV can be rich in important spectral information.

  10. Static and Dynamic Disorder in Bacterial Light-Harvesting Complex LH2: A 2DES Simulation Study.

    Science.gov (United States)

    Rancova, Olga; Abramavicius, Darius

    2014-07-10

    Two-dimensional coherent electronic spectroscopy (2DES) is a powerful technique in distinguishing homogeneous and inhomogeneous broadening contributions to the spectral line shapes of molecular transitions induced by environment fluctuations. Using an excitonic model of a double-ring LH2 aggregate, we perform simulations of its 2DES spectra and find that the model of a harmonic environment cannot provide a consistent set of parameters for two temperatures: 77 K and room temperature. This indicates the highly anharmonic nature of protein fluctuations for the pigments of the B850 ring. However, the fluctuations of B800 ring pigments can be assumed as harmonic in this temperature range.

  11. Research ICT Africa (RIA!) - phase III | CRDI - Centre de recherches ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Research ICT Africa (RIA!) - phase III. Depuis la création du réseau RIA! en 2003, ses responsables ont mené avec succès des études portant tant sur l'offre que sur la demande afin de permettre de mieux comprendre l'accès aux TIC et leur utilisation en Afrique. Au cours des deux premières phases du projet (nos 101584 ...

  12. Evaluation des risques-projet par une approche AHP/WPM: Application à un projet réel BTP

    OpenAIRE

    LMOUSSAOUI , Hafida; JAMOULI , Hicham

    2015-01-01

    International audience; La complexité et l'incertitude de l'environnement sont à l'origine de nouveaux défis auxquels les entreprises du domaine BTP font face quotidiennement. La maîtrise des paramètres des projets devient donc une nécessité pour leur pérennité. L'objectif du management des risques est de maîtriser ces paramètres pendant toutes les phases du projet. Il s'appuie sur un processus continu et itératif permettant successivement d'identifier et analyser les risques encourus, les év...

  13. Enquête de satisfaction des restaurants

    CERN Multimedia

    Staff Association

    2016-01-01

    Comité de surveillance des restaurants L’Association du personnel est représentée dans plusieurs comités dont le Comité de surveillance des restaurants (CSR) qui a pour mandat : de donner son avis sur toute question relative à la politique générale de l’Organisation en matière de restauration sur le site, y compris en ce qui concerne les termes et l’attribution des contrats d’exploitation des restaurants ; de définir dans le cadre des contrats d’exploitation des restaurants, les prestations correspondant aux besoins et, dans la mesure du possible, aux désirs du personnel ; de surveiller les prestations des restaurants, y compris en ce qui concerne la qualité et la préparation des produits ; de négocier avec les concessionnaires des restaurants au sujet des tarifs et de surveill...

  14. Administration et gestion des contrats XL

    CERN Document Server

    Senouf, J

    2000-01-01

    Les grands contrats de travaux génèrent un grand nombre de commandes (OSVC) passées par un grand nombre de responsables techniques. Ils sont généralement basés sur des bordereaux de prix associés à un éventail de conditions économiques adaptées aux besoins complexes et variés des multiples utilisateurs du CERN nécessitant des calculs sophistiqués. L'administration des commandes, le suivi des travaux et de la facturation doivent répondre aux besoins de tous les acteurs. Les responsables techniques doivent jouir de la plus large indépendance administrative dans le respect des règlements CERN et des conditions contractuelles. Le contrôle des métrés et décomptes doit être rigoureux et d'une traçabilité complète. L'utilisation des bases de données Oracle a déjà permis l'intégration des données administratives et techniques. Le Web nous invite à une communication totale et transparente entre les utilisateurs, les services techniques et les contractants. De nouveaux types de contrat so...

  15. Spectral analysis of the structure of ultradispersed diamonds

    Science.gov (United States)

    Uglov, V. V.; Shimanski, V. I.; Rusalsky, D. P.; Samtsov, M. P.

    2008-07-01

    The structure of ultradispersed diamonds (UDD) is studied by spectral methods. The presence of diamond crystal phase in the UDD is found based on x-ray analysis and Raman spectra. The Raman spectra also show sp2-and sp3-hybridized carbon. Analysis of IR absorption spectra suggests that the composition of functional groups present in the particles changes during the treatment.

  16. Timing calibration and spectral cleaning of LOFAR time series data

    NARCIS (Netherlands)

    Corstanje, A.; Buitink, S.; Enriquez, J. E.; Falcke, H.; Horandel, J. R.; Krause, M.; Nelles, A.; Rachen, J. P.; Schellart, P.; Scholten, O.; ter Veen, S.; Thoudam, S.; Trinh, T. N. G.

    We describe a method for spectral cleaning and timing calibration of short time series data of the voltage in individual radio interferometer receivers. It makes use of phase differences in fast Fourier transform (FFT) spectra across antenna pairs. For strong, localized terrestrial sources these are

  17. La production mondiale des vins

    Directory of Open Access Journals (Sweden)

    Pierre GALET

    1970-06-01

    On sait peu de choses précises sur l'origine de la culture de la vigne en Gaule. Il est probable qu'il existait des lambrusques sauvages dans les forêts et les sous-bois dont les habitants récoltaient les raisins pour les consommer à l'état frais et peut-être en tiraient-ils aussi une boisson fermentée comme ils le faisaient pour l'orge ou pour le miel (hydromel. Il est vraisemblable aussi que les navigateurs phocéens, venus commercer sur les rivages de la Méditerranée, apportèrent du vin aux gaulois, leur apprirent à tailler la vigne et finalement, en établissant des comptoirs, amenèrent des boutures de vignes de leur propre pays. On sait que les gaulois apprécièrent très vite le vin et ce fut une des raisons de leurs invasion de la Toscane pour y consommer sur place cette « boisson magique ». Plus tard avec l'occupation romaine la culture de la vigne s'étendit dans toute la province narbonnaise, dans la vallée du Rhône jusqu'aux portes de Lyon, puis en Aquitaine. A leur tour les romains se mirent à apprécier les vins gaulois, de qualité supérieure à ceux récoltés en Italie sur les Hautains. A l'aide de la navigation fluviale sur le Rhône les vins gagnèrent Rome, ainsi que ceux embarqués dans les petits ports du rivage méditerranéen. Puis au cours des siècles et grâce notamment aux religieux catholiques la vigne se répandit dans toutes les provinces. A la veille de la Révolution, en 1788, on estimait la superficie cultivée à 1.567.000 hectares, produisant 27 millions d'hectolitres. Au cours du XIXe siècle, les plantations augmentèrent en raison des facilités de transport que permettait l'établissement des lignes de chemin de fer. Le ravitaillement des grandes villes fut assuré par la création d'un important vignoble dans le Midi. En 1875, la superficie cultivée dépassait 2,4 millions d'hectares et la France produisit 83,8 millions d'hectolitres, record absolu qui ne fut jamais plus atteint depuis. La crise phyllox

  18. La territorialisation des politiques environnementales

    Directory of Open Access Journals (Sweden)

    Amédée Mollard

    2010-10-01

    Full Text Available Le point de départ de cet article est la grande variabilité de la pollution nitrique diffuse de l’eau due à l’agriculture. Celle-ci dépend en particulier du climat, des types de sol et des systèmes de production agricole. Nos recherches réalisées de façon interdisciplinaire à partir de deux sites différents en France, montrent que cette hétérogénéité spatio-temporelle conditionne les pratiques agricoles mises en œuvre pour réduire la pollution au niveau de la norme admise. De ce fait, les pratiques les plus « coût-efficaces » diffèrent d’un territoire à l’autre, en fonction des caractéristiques locales. Ces résultats mettent donc en évidence une efficacité potentielle d’une territorialisation des politiques publiques. En théorie, de telles politiques sont considérées comme optimales par les économistes, car elles incitent les agents à moduler leurs efforts en fonction de la sensibilité du milieu. Mais, selon les études empiriques, cet avantage serait annulé par un coût élevé de mise en œuvre, de contrôle et de surveillance. Pour maintenir leur avantage sur des politiques uniformes, les politiques territorialisées devraient être mises en œuvre à un niveau spatial optimal. Un tel niveau devrait au minimum atteindre un compromis entre l’économie réalisée grâce à une modulation adaptée aux conditions locales et les sur-coûts dus à la décentralisation des solutions mises en œuvre. Cet article analyse la pertinence d’une prise en compte de ces spécificités par des politiques territorialisées. L’efficacité d’une régulation différenciée de la pollution nitrique est étudiée ici en évaluant l’importance de la variabilité spatiale des paramètres physiques et des coûts de la territorialisation.The paper starts with the wide variability of nonpoint water nitrogenous pollution generated by agriculture. This variability depends especially on climate, soil types and farming

  19. Studies of the Solid and Liquid Phases of HF, HCl and HBr by Slow-Neutron Inelastic Scattering; Etude des Phases Solide et Liquide de HF, HCl Et HBr par la Diffusion Inelastique des Neutrons Lents; 0418 0417 0423 0427 0415 041d 0418 0415 0422 0412 0415 0420 0414 042b 0425 0418 0416 0418 0414 041a 0418 0425 0424 0410 0417 HF, HCl I HBr 0421 041f 041e 041c 041e 0429 042c 042e 041d 0415 0423 041f 0420 0423 0413 041e 0413 041e 0420 0410 0421 0421 0415 042f 041d 0418 042f 041c 0415 0414 041b 0415 041d 041d 042b 0425 041d 0415 0419 0422 0420 041e 041d 041e 0412 ; Estudio de las Fases Solida y Liquida del HF, HCl Y HBr por Dispersion Inelastica de Neutrones Lentos

    Energy Technology Data Exchange (ETDEWEB)

    Boutin, H. [Picatinny Arsenal, Dover, NJ (United States); Brookhaven National Laboratory, Upton, NY (United States); Safford, G. J. [Brookhaven National Laboratory, Upton, NY (United States)

    1965-06-15

    be attributed to a weaker degree of association, which is expected from the decreasing electronegativity of the anion. The systematic study of these spectra in the various phases and at variais temperatures allows a distinction to be made between the low frequency motions characteristic of the lattice or of an hydrogen-bonded chain and those low frequency motions which involve nearest-neighbour interactions or short-range forces. The results of these measurements are in agreement with previous infrared data and indicate that hydrogen bonding is an influential factor in explaining the spectra of the solid phases of both HCl and HBr. These data are not in agreement, however, with theories that account for the solid phases of these compounds only in terms of simple dipole arrays or in terms of long-range interactions involving the dipole moment of one single unit interacting with an average electric field. (author) [French] Les auteurs ont etudie les phases liquide et solide de HF, HCl et HBr entre les raies d'absorption 30 et 1200 cm{sup -1} employant la methode de la diffusion inelastique des neutrons froids (0, 005 eV). Ils ont procede a ces mesures pour examiner systematiquement l'influence qu'un accroissement du degre d'electronegativite et la dimension des anions exercent sur les mouvements moleculaires de basse frequence dans la phase solide et la phase liquide. L'etude a d'abord porte sur HF du fait que les donnees obtenues par diffraction des rayons X avaient montre que dans ce compose a l'etat solide apparaissaient de longues chaines en zigzag liees par l'hydrogene. Les spectres des neutrons inelastiquement diffuses par les phases liquide et solide de HF font ressortir le haut degre d'association qui existe dans toute la phase liquide en raison de la liaison hydrogenee. Aux fins d'interpretation, les auteurs comparent les donnees relatives a HF a des donnees analogues relatives aux ions HF{sub 2}{sup -} et H{sub 2}F{sub 3}{sup -} dont les structures sont

  20. DES EFFETS DURABLES DES VIES TRANSFORMÉES

    International Development Research Centre (IDRC) Digital Library (Canada)

    Son but est simple : veiller à ce que les personnes les plus vulnérables dans le monde, en particulier ... Simple et pourtant très efficace, le filtre biosable fournit de l'eau potable dans plus de 300 000 foyers de par le ... de rétablir la fertilité des sols dégradés par l'extraction de l'argile nécessaire à la fabrication de briques, ...

  1. Regroupement des statistiques sur le secteur des TIC et analyse ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    La présence et l'influence des technologies de l'information et de la communication (TIC) continuent de s'élargir et de s'accroître, tout comme leurs répercussions sur le développement économique. Toutefois, il reste encore beaucoup de travail à faire avant de pouvoir comprendre d'une manière systématique et ...

  2. Étude cytogenetique des aberrations chromosomiques chez des ...

    African Journals Online (AJOL)

    Ces techniciens et volontaires témoins ont été soumis à l'épreuve de prélèvement de 5 ml de sang veineux au pli du coude dans des tubes d'héparine sodique. Après 48 ... These technicians and Volunteers (controls) were subjected to the test sample of 5 ml of venous blood to the elbow crease in sodium heparin tubes.

  3. Des experts discutent des conflits non conventionnels dans les ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    21 juil. 2015 ... Le rapport souligne les principaux défis à relever lorsqu'il est question de conflits non conventionnels et de violence dans les Amériques. ... Bien que de nombreux États aient recours à la médiation avec des acteurs du crime organisé en vue de réduire le nombre de leurs actes de violence ou d'y mettre fin, ...

  4. Effets des biomasses vertes de Tithonia diversifolia et des engrais ...

    African Journals Online (AJOL)

    même dans les sols peu fertiles (McKey et al.,. 2012 ; Temegne et al., 2015). Cependant, il peut aussi produire beaucoup plus lorsqu'il est cultivé avec un supplément judicieux d'engrais. La fertilisation minérale conventionnelle est incompatible avec le contexte économique du paysan camerounais du fait du coût élevé des ...

  5. Caractérisation des plantes médicinales à flavonoïdes des marchés ...

    African Journals Online (AJOL)

    Les espèces guinéo-congolaises sont les plus abondantes et le mode de dissémination majoritaire des diaspores est la zoochorie. Les plantes à flavonoïdes les plus utilisées sont : Combretum micranthum, Aloe vera, Ageratum conyzoïdes et Cylicodiscus gabonensis. Elles rentrent dans le traitement de 73 maladies parmi ...

  6. Substitution dynamical systems spectral analysis

    CERN Document Server

    Queffélec, Martine

    2010-01-01

    This volume mainly deals with the dynamics of finitely valued sequences, and more specifically, of sequences generated by substitutions and automata. Those sequences demonstrate fairly simple combinatorical and arithmetical properties and naturally appear in various domains. As the title suggests, the aim of the initial version of this book was the spectral study of the associated dynamical systems: the first chapters consisted in a detailed introduction to the mathematical notions involved, and the description of the spectral invariants followed in the closing chapters. This approach, combined with new material added to the new edition, results in a nearly self-contained book on the subject. New tools - which have also proven helpful in other contexts - had to be developed for this study. Moreover, its findings can be concretely applied, the method providing an algorithm to exhibit the spectral measures and the spectral multiplicity, as is demonstrated in several examples. Beyond this advanced analysis, many...

  7. Spectral characterization of natural backgrounds

    Science.gov (United States)

    Winkelmann, Max

    2017-10-01

    As the distribution and use of hyperspectral sensors is constantly increasing, the exploitation of spectral features is a threat for camouflaged objects. To improve camouflage materials at first the spectral behavior of backgrounds has to be known to adjust and optimize the spectral reflectance of camouflage materials. In an international effort, the NATO CSO working group SCI-295 "Development of Methods for Measurements and Evaluation of Natural Background EO Signatures" is developing a method how this characterization of backgrounds has to be done. It is obvious that the spectral characterization of a background will be quite an effort. To compare and exchange data internationally the measurements will have to be done in a similar way. To test and further improve this method an international field trial has been performed in Storkow, Germany. In the following we present first impressions and lessons learned from this field campaign and describe the data that has been measured.

  8. Approche probabiliste des milieux poreux hétérogènes ou fracturés en relation avec les écoulements diphasiques Probabilistic Approach to Heterogeneous Or Fractured Porous Media in Relation to Two-Phase Flows

    Directory of Open Access Journals (Sweden)

    Jacquin C.

    2006-11-01

    Full Text Available La prise en compte des particularités structurales des gisements pétroliers fracturés ou hétérogènes est nécessaire à l'amélioration des prévisions de production. La description de ce type de gisements relève d'une approche probabiliste, qui conduit à une estimation des caractéristiques de la roche réservoir : distribution des dimensions des blocs d'un réservoir fissuré, échelles d'hétérogénéité. Ces caractéristiques sont introduites dans les modèles déterministes qui décrivent l'écoulement des fluides. On présente en particulier les problèmes que pose la transposition au gisement des résultats obtenus au laboratoire sur petits échantillons : changement d'échelle géométrique, estimation de la récupération finale et de l'évolution de la production en fonction du temps. The structural features of fractured or heterogenous oil fields must be taken into consideration to improve production forecasting. The description of such fields is based on a probabilistic approach leading to an estimate of the characteristics of the reservoir rock, i. e. distribution of the block sizes of a fissured reservoir, scales of heterogeneity. These characteristics are fed into deterministic models that describe fluid flows. Special attention is paid to problems raised by the transposition of laboratory results obtained on small samples to a field. Such problems include the change in geometric scale, the estimating of ultimate recovery and how production will evolve in time.

  9. 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)

  10. Dépollution des gaz d'échappement des moteurs diesel au moyen de pots catalytiques Depolluting Exhaust Gases from Diesel Engines by Catalytic Mufflers

    Directory of Open Access Journals (Sweden)

    Goldenberg E.

    2006-11-01

    Full Text Available On présente dans cet article les résultats d'une première série de recherches sur la dépollution des gaz d'échappement des moteurs diesel au moyen de pots catalytiques. L'efficacité des catalyseurs à base de platine pour l'oxydation du monoxyde de carbone et des hydrocarbures imbrûlés a pu être établie par des essais sur banc moteur et sur véhicule. L'emploi de certaines phases actives à base de métaux non nobles permet d'autre part d'abaisser la température de début d'oxydation des particules de suie de 380 à 250 °C environ, avec, entre 250 et 350 °C, élimination de 15 à 20 % des produits piégés. L'essai de divers media filtrants a mis en évidence l'importance des phénomènes d'adsorption des revêtements en alumine et a orienté la recherche vers de nouveaux supports pour filtres catalytiques. This article describes the results of a first series of research on the depollution of exhaust gases from diesel engines by catalytic mufflers. The effectiveness of platinum-base catalysts for the oxidation of carbon monoxide and unburned hydrocarbons was determined by test on an engine test bed and on vehicles on the road. The use of some active non-noble metal phases reduced on the other hand the starting oxidation temperature of soot particulates from 380°C to about 250°C, eliminating 15 to 20% of the trapped products between 250 and 350° C. Tests of different filtering media revealed the importance of adsorption phenomena on alumina coatings and directed research toward new supports for catalytic filters.

  11. Adiabatic theorem and spectral concentration

    International Nuclear Information System (INIS)

    Nenciu, G.

    1981-01-01

    The spectral concentration of arbitrary order, for the Stark effect is proved to exist for a large class of Hamiltonians appearing in nonrelativistic and relativistic quantum mechanics. The results are consequences of an abstract theorem about the spectral concentration for self-ad oint operators. A general form of the adiabatic theorem of quantum mechanics, generalizing an earlier result of the author as well as some results of Lenard, is also proved [ru

  12. NMR study of hyper-polarized {sup 129}Xe and applications to liquid-phase NMR experiments; Etude de la resonance magnetique nucleaire du Xenon{sup 129} hyperpolarise et applications en RMN des liquides

    Energy Technology Data Exchange (ETDEWEB)

    Marion, D

    2008-07-15

    In liquid samples where both nuclear polarization and spin density are strong, the magnetization dynamics, which can be analysed by NMR (nuclear magnetic resonance) methods, is deeply influenced by the internal couplings induced by local dipolar fields. The present thesis describes some of the many consequences associated to the presence in the sample of concentrated xenon hyper-polarized by an optical pumping process. First, we deal with the induced modifications in frequency and line width of the proton and xenon spectra, then we present the results of SPIDER, a coherent polarization transfer experiment designed to enhance the polarization of protons, in order to increase their NMR signal level. A third part is dedicated to the description of the apparition of repeated chaotic maser emissions by un unstable xenon magnetization coupled to the detection coil tuned at the xenon Larmor frequency (here 138 MHz). In the last part, we present a new method allowing a better tuning of any NMR detection probe and resulting in sensible gains in terms of sensitivity and signal shaping. Finally, we conclude with a partial questioning of the classical relaxation theory in the specific field of highly polarized and concentrated spin systems in a liquid phase. (author)

  13. On the modelling and the analysis of two-phase flow instabilities in pipeline-riser systems; Modelisation et analyse des instabilites d'ecoulements diphasiques dans les conduites petrolieres du type pipeline-riser

    Energy Technology Data Exchange (ETDEWEB)

    Zakarian, E.

    2000-03-10

    Recent estimations predict that over half the remaining offshore oil and gas reserves are located in deep water and marginal fields. For such reserves, economic recovery methods are required. Then, multiphase flows are transported within pipelines and separated on treatment platforms built in shallow water or processed in onshore facilities. Unfortunately, hydrodynamic instabilities may occur whenever gas and liquid flow in a pipeline, generating serious operating problems. This dissertation presents a new way to model two-phase flows in pipelines such as pipeline-riser systems. Equations are algebraic and differential. Their smoothness depends on the closure laws of the problem such as slip or friction laws. Smooth forms of these closure laws are presented for the first time in this dissertation. Therefore, a mathematical analysis of our model fits into a classical frame: a linear analysis leads to an analytical expression of the boundary between stable and unstable flows. A nonlinear analysis provides for the first time, the bifurcation curves of gas-liquid flows in pipe-riser systems, locally round their stability boundary. (author)

  14. The judgement of the Federal Constitutional Court on the nuclear phase-out in Germany. Every light hat its shadow; Das Urteil des BVerfG zum Atomausstieg in Deutschland. Licht und Schatten

    Energy Technology Data Exchange (ETDEWEB)

    Leidinger, Tobias [Luther Rechtsanwaltsgesellschaft, Duesseldorf (Germany)

    2017-01-15

    The 13th amendment of the German Atomic Energy Act (AtG) was a direct result of the accident in Fukushima in March 2011. As a result, not only the provisional (three-month) shutdown of the eight nuclear power plants immediately shut down after the accident finally passed the parliament, but fixed shutdown times were also decided for the remaining nine NPP's. This was both an increase of the AtG amendment of 2002 and the extension of the NPP licenses decided a few months earlier. Nuclear energy should therefore continue to serve as a ''bridge technology'' within the framework of the Federal Government's energy concept for a longer period. On 6 December 2016 the Federal Constitutional Court (BVerfG) has decided that the act on the accelerated phasing-out of nuclear energy in Germany is partly unconstitutional. The judgment is clear on a whole series of legal issues. At the same time, it raises new questions with a view to the final clarification of the compensation.

  15. The coordination of research and innovation activities relative to an emergent technology: the case of batteries for electric and hybrid vehicles; La coordination des activites de recherche et d'innovation dans les phases d'emergence: le cas des batteries pour vehicules electriques et hybrides

    Energy Technology Data Exchange (ETDEWEB)

    Larrue, Ph.

    2000-05-23

    In this thesis, we try to provide elements of a non-deterministic view of the coordination of research activities in the phase of emergence. Firstly, we try to identify the variables that determinate the strength and the characteristics of the imperative of coordination in this very preliminary period of an innovation process. Secondly, we try to evaluate the institutional arrangements that can effectively sustain the coordination of the activities of the various interdependent actors more or less involved in the innovation process. The basic idea of the thesis is that technological innovations do not originate as isolated according to a hypothetical underlying 'nature of the technology', especially when they are controversial and subject to great uncertainties as is the case with regard to batteries for Electric and hybrid Vehicles (EVs). Innovations appear to be generated by means of the interactions of a number of organizations belonging to different 'spheres' (different industries, scientific disciplines, public institutions, etc.). In order to validate a new area of opportunity which is still very uncertain at this preliminary stage, the competences and interests of these different organizations must be coordinated. Because of the complex mix of economic and technological barriers faced by the actors taking part in this innovation process, the area of batteries for electric and hybrid vehicles is the 'perfect laboratory' to investigate the institutional arrangements that can sustain the coordination of research and innovation activities relating to an emerging technology. The empirical and theoretical investigations are mainly focused on pre-competitive research consortia such as the United-States Advanced Battery Consortium (USABC). This case study is conducted through in-depth interviews with key-actors of the area of batteries and electric vehicles. We also use the results of an on-line experts opinions survey we performed

  16. The coordination of research and innovation activities relative to an emergent technology: the case of batteries for electric and hybrid vehicles; La coordination des activites de recherche et d'innovation dans les phases d'emergence: le cas des batteries pour vehicules electriques et hybrides

    Energy Technology Data Exchange (ETDEWEB)

    Larrue, Ph

    2000-05-23

    In this thesis, we try to provide elements of a non-deterministic view of the coordination of research activities in the phase of emergence. Firstly, we try to identify the variables that determinate the strength and the characteristics of the imperative of coordination in this very preliminary period of an innovation process. Secondly, we try to evaluate the institutional arrangements that can effectively sustain the coordination of the activities of the various interdependent actors more or less involved in the innovation process. The basic idea of the thesis is that technological innovations do not originate as isolated according to a hypothetical underlying 'nature of the technology', especially when they are controversial and subject to great uncertainties as is the case with regard to batteries for Electric and hybrid Vehicles (EVs). Innovations appear to be generated by means of the interactions of a number of organizations belonging to different 'spheres' (different industries, scientific disciplines, public institutions, etc.). In order to validate a new area of opportunity which is still very uncertain at this preliminary stage, the competences and interests of these different organizations must be coordinated. Because of the complex mix of economic and technological barriers faced by the actors taking part in this innovation process, the area of batteries for electric and hybrid vehicles is the 'perfect laboratory' to investigate the institutional arrangements that can sustain the coordination of research and innovation activities relating to an emerging technology. The empirical and theoretical investigations are mainly focused on pre-competitive research consortia such as the United-States Advanced Battery Consortium (USABC). This case study is conducted through in-depth interviews with key-actors of the area of batteries and electric vehicles. We also use the results of an on-line experts opinions survey we performed. (author)

  17. La participation des femmes à la vie politique se traduit par des ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    La participation des femmes à la vie politique se traduit par des économies locales plus vigoureuses. 08 juin 2016. Image. Des femmes assistent à une réunion d'un groupe d'entraide près d'. Edgard Rodriguez - IDRC. Des femmes assistent à une réunion d'un groupe d'entraide près d'Hyderabad, en Inde. Keenara ...

  18. statut de la matiere organique des cambisols et des lixisols sous

    African Journals Online (AJOL)

    Administrateur

    L'étude vise à évaluer la matière organique des Cambisols et des Lixisols sous formations naturelles de longue durée en zone climatique nord-soudanienne et à établir, les relations entre ... sont supérieures à celles des sols des zones sahélienne et sud-soudanienne. ... globale a eu une corrélation positive avec le pH.

  19. Renforcement de l'autonomie des collectivités au moyen des ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Cette subvention permettra au ministère des Communications et des Technologies de l'information de l'Égypte ainsi qu'au fonds spécial réservé aux TI de consolider le modèle actuel des clubs de TI en Égypte, par l'entremise de services d'assistance sur demande, d'activités de formation à l'intention du personnel des ...

  20. Accès à l'eau : des solutions techniques et sociales aident des ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Grâce à la modélisation par ordinateur faisant appel à des techniques de pointe et à la consultation des collectivités, l'organisme bolivien Agua Sustentable a trouvé des solutions politiques à des conflits qui auraient pu s'avérer désastreux au sujet de l'accès à l'eau. Cet organisme de recherche subventionné par le CRDI a ...

  1. Connaissances, attitudes et pratiques des prestataires de santé des ...

    African Journals Online (AJOL)

    ... des prestataires interrogés avaient respectivement une bonne connaissance des facteurs de risque et des moyens de dépistage. Les signes évocateurs et les examens complémentaires nécessaires au diagnostic du cancer du sein étaient connus par 15,3 % des prestataires. La définition du cancer du sein et les moyens ...

  2. Incidence des prix et des taxes sur la consommation de produits du ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Incidence des prix et des taxes sur la consommation de produits du tabac en Argentine, en Bolivie et au Chili. Partout en Amérique du Sud, les adultes et les enfants font une grande consommation de tabac. Un nouveau projet de recherche se penchera sur les avantages et les limites des stratégies de fixation des prix et de ...

  3. Exécution des marchés publics mise en oeuvre administrative et financière

    CERN Document Server

    Serr, Fabien

    2013-01-01

    L'exécution des marchés publics constitue la phase critique de mise en oeuvre de tous les éléments préparés lors de la passation du marché ; c'est aussi la période de gestion administrative, financière et technique des événements prévus ou non sur un chantier. Cet ouvrage opérationnel et juridique détaille la mise en oeuvre du marché et décrypte, au travers de 27 chapitres, chaque phase de l'exécution administrative et financière de tout type de marché : suivi, sous-traitance, garantie, paiement, décompte, réception, recours amiables, etc. Exécution des marchés publics permet de : - disposer d'une vue d'ensemble de l'exécution des marchés publics ; - s'approprier le cadre juridique de l'exécution (Code des marchés publics, textes réglementaires ou législatifs, CCAG et règles de la comptabilité publique, etc.) ; - maîtriser les différentes phases de l'exécution et leur articulation ; - respecter l'ensemble des étapes, les points de procédures à suivre, etc. De nombreux tabl...

  4. La production mondiale des vins

    Directory of Open Access Journals (Sweden)

    Pierre GALET

    1969-09-01

     Le continent européen constitue le principal foyer de la culture de la vigne. Il vient en tête, non seulement par l'importance de la superficie cultivée, mais également par le volume global de la récolte et par la qualité des produits qui y sont récoltés : vins fins rouges, rosés et blancs, vins mousseux, vins de dessert ou vins généreux, eaux-de-vie, raisins de table frais et raisins secs. Les pays européens sont également les principaux consommateurs de vins du monde et la majeure partie des échanges commerciaux se font vers l'Europe ou partent de ce continent.

  5. Poser et reposer des choix.

    Directory of Open Access Journals (Sweden)

    Corinne Van Hauwermeiren- Echement

    2009-10-01

    Full Text Available IntroductionEn 1955, le legs de la collection Franckignoul – composée notamment d’un ensemble de quatre panneaux du XVIe siècle – vient enrichir les collections du Musée des Beaux-Arts de la Ville de Liège (Belgique. La fermeture de ce dernier en 1976 débouche sur  la scission des collections. Une partie est donnée au Musée de l’Art Wallon, l’autre partie allant au Musée d’Art Moderne et d’Art Contemporain (Mamac. Toutes les œuvres n’entrant pas dans ces deux collections sont reléguées en r...

  6. On the structure of heavy metals; Sur la structure des metaux lourds

    Energy Technology Data Exchange (ETDEWEB)

    Friedel, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Faculte des Sciences de l' Universite de Paris, 75 (France)

    1958-07-01

    The properties of the last series of Mendeleef's table are compared with those of the elements of the preceding series. This comparison suggests an electronic structure of the 'transition metal' type, with narrow bands, at the beginning of this series (up to certain phases at least of plutonium); then of the rare earth metal type, with independent non-saturated internal layers, further on in the series. The 5 f orbits seem to play an important part in these two types of structure, from uranium on. A more detailed study of the very heavy elements (americium and beyond) and alloys would allow these conclusions to be confirmed. Certain general points, concerning the nature of homopolar connections and paramagnetism in the transition metals, are developed in an additional section. (author) [French] Les proprietes des elements de la derniere serie du tableau de Mendeleef sont comparees a celles des elements des series precedentes. Cette comparaison suggere une structure electronique du type 'metal de transition', a bandes etroites, au debut de cette serie (jusqu'a certaines phases au moins du plutonium); puis du type d'un metal des terres rares, a couches internes non saturees independantes, au-dela dans la serie. Les orbitales 5 f semblent jouer un r e important, dans ces deux types de structures, a partir de l'uranium. Une etude plus poussee des elements tres lourds (americium et au-dela) et des alliages permettrait de confirmer ces conclusions. Certains points generaux, concernant la nature des liaisons homopolaires et le paramagnetisme dans les metaux de transition, sont developpes en annexe. (auteur)

  7. (TEC) et ciblage des pauvres au Mali

    International Development Research Centre (IDRC) Digital Library (Canada)

    Comment est-ce que c'est vrai. La preuve par … □ Différentiel de ciblage entre P et NP. □ Part normalisée de consommation/achat des Pauvres. □ Part normalisée de la pression fiscale. (totale et de porte) sur les achats des P. □ Part normalisée des "exonérations" revenant aux Pauvres ...

  8. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    programme d'installations minières pour l'exploitation de l'or et du manganèse, intéressant des emprises foncières importantes. ... pour maitriser les risques liés aux sols pollués, lesquels peuvent conduire à des effets négatifs sur le long terme Meusy, & Giorni .... kaolinite et de type bentonite industrielle (SFBD). Le pH des ...

  9. Dynamik des Kaufverhaltens im Bio-Sortiment

    OpenAIRE

    Buder, Fabian; Hamm, Ulrich; Bickel, Malte; Bien, Barbara; Michels, Paul

    2010-01-01

    Das Gesamtziel des vorliegenden Forschungsprojekts war es, eine detaillierte Informationsgrundlage zum tatsächlichen Kaufverhalten von deutschen Haushalten bei ökologischen Lebensmitteln auf der Basis von Haushaltspaneldaten zu erstellen. Dazu sollten zum einen relevante Aspekte des Kaufverhaltens von Haushalten bei Öko-Lebensmitteln im Zeitverlauf von 2004 bis 2008 analysiert und zum anderen die Einflussfaktoren des Kaufverhaltens bei Öko-Lebensmitteln für das Jahr 2008 identifiziert werden....

  10. Revision des Symphurus du Siboga

    NARCIS (Netherlands)

    Chabanaud, Paul

    1955-01-01

    Ce m’est un devoir particulièrement agréable que de saisir l’occasion de ce petit mémoire pour remercier M. L. F. DE BEAUFORT, M. H. ENGEL, Directeur du Zoologisch Museum, ainsi que M. J. J. HOEDEMAN de l’accueil qu’à diverses reprises, j’ai reçu de leur part, au Zoölogisch Museum, et aussi des

  11. Study of the role of film flows in three-phase displacement mechanisms in porous media; Etude du role des ecoulements par film dans les mecanismes de deplacement triphasique en milieux poreux

    Energy Technology Data Exchange (ETDEWEB)

    Bataillon, D

    1996-12-11

    The determination of the role of liquid films in three phase flows in porous media is very important for enhanced oil recovery by gas injection in a petroleum reservoir. The existence of liquid films (water, oil), their thickness and their stability, control the distribution of fluids and the displacement of these fluids in the reservoir. The target of this research is to obtain, from experimental observations, the microscopic rules of flow by films taking into account the elementary mechanisms controlling the displacement of fluids. For this, a method of liquid film flow thickness measurement is developed in a quartz Hele-Shaw cell. It is based on infrared spectrometry, used for the first time to our knowledge for such an application, which gives the possibility to follow the drainage kinetics of oil and water in the presence of gas. When the thick oil film is initially stable on water in the presence of gas, it slowly drains until it reaches a constant thickness of about 20 nm. This film may breaks down into micro droplets of less than few micrometers in diameter. When this thick oil film is not initially stable, it immediately breaks down into droplets of 10 to 20 {mu}m in diameter prevents any oil flow. For spreading conditions, the initial oil thickness of about 200 nm is calculated form the Ca capillary number. The flow kinetics of this film is then determined when macroscopic forces are predominant. Finally, for the estimation of the stabilisation thickness, disjoining pressure isotherms, based on long-scale intermolecular forces (VdW), are calculated for pure n-alkanes. In order to study the macroscopic flow parameters, gravity drainage experiments are carried out in a 2D glass network (micro-model). Measurements of oil production (weight) and residual saturations (image analysis) show clearly the influence of the initial stability of oil, coating water in the presence of gas, on the flow mechanisms. (author) 73 refs.

  12. Contribution des TICs à l'abandon des mutilations génitales ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Contribution des TIC à l'abandon des MGF en Afrique de l'Ouest francophone : rôle des jeunes citoyennes; rapport technique no. 5 (rapport technique final), 18 octobre 2008 - 31 mars 2009. Download PDF. Related content. New website will help record vital life events to improve access to services for all. A new website ...

  13. Etat des lieux de la gestion des insecticides au Togo, Afrique de l ...

    African Journals Online (AJOL)

    Pour parvenir à une gestion optimale des maladies à transmission vectorielle ou tout au moins la nuisance culicidienne, une surveillance permanente des facteurs de risque devient nécessaire. Le principal facteur de risque est le vecteur qui transmet la maladie, et le contrôle du vecteur passe par des stratégies de lutte qui ...

  14. Ethnobotanique des plantes médicinales anti hémorroïdaires des ...

    African Journals Online (AJOL)

    SARAH

    2015-12-31

    Dec 31, 2015 ... but est de valoriser la médecine à base des plantes dans le traitement des pathologies ... médicinales anti hémorroïdaires et le coût réduit des recettes serait pour les populations démunies, ...... l'Afrique, Unesco/Aetfat/Unso.

  15. Spectral estimation for characterization of acoustic aberration.

    Science.gov (United States)

    Varslot, Trond; Angelsen, Bjørn; Waag, Robert C

    2004-07-01

    Spectral estimation based on acoustic backscatter from a motionless stochastic medium is described for characterization of aberration in ultrasonic imaging. The underlying assumptions for the estimation are: The correlation length of the medium is short compared to the length of the transmitted acoustic pulse, an isoplanatic region of sufficient size exists around the focal point, and the backscatter can be modeled as an ergodic stochastic process. The motivation for this work is ultrasonic imaging with aberration correction. Measurements were performed using a two-dimensional array system with 80 x 80 transducer elements and an element pitch of 0.6 mm. The f number for the measurements was 1.2 and the center frequency was 3.0 MHz with a 53% bandwidth. Relative phase of aberration was extracted from estimated cross spectra using a robust least-mean-square-error method based on an orthogonal expansion of the phase differences of neighboring wave forms as a function of frequency. Estimates of cross-spectrum phase from measurements of random scattering through a tissue-mimicking aberrator have confidence bands approximately +/- 5 degrees wide. Both phase and magnitude are in good agreement with a reference characterization obtained from a point scatterer.

  16. La production mondiale des vins

    Directory of Open Access Journals (Sweden)

    Pierre GALET

    1972-06-01

    Full Text Available La culture de la vigne en Autriche remonterait à l'occupation romaine, les premières plantations ayant été faites par les légions romaines de l'empereur Probus, dans la seconde moitié du IIIe siècle (Probus était né à Sirmium près du Danube et il favorisa l'extension des vignobles dans cette région pour approvisionner ses armées. Après la chute de l'empire romain et les invasions des Awares, on doit à Charlemagne le renouveau de la culture de la vigne, notamment dans la Wachau, en Basse- Autriche. Puis plus tard, à chaque avance de la colonisation, les vignes se répandirent sur les bords du Danube et dans les vallées latérales, l'extension étant favorisée par les communautés religieuses catholiques qui devinrent propriétaires de grands vignobles. La navigation sur le fleuve fut également un facteur favorable pour la culture de la vigne. Au XVIe siècle, apogée des cultures, le vin se vendait jusqu'en Pologne et dans les Etats Baltes.

  17. Modalites de consommation et valeur nutritionnelle des ...

    African Journals Online (AJOL)

    Les légumineuses niébé, voandzou et zamnè sont consommées sous forme de ragout et de plats associés à des céréales respectivement par 99%, 93% et 76%. L'arachide et le soja sont utilisés comme des ingrédients ou comme des collations. Les légumineuses ont des teneurs importantes en protéines, 35,76%, 31,04%, ...

  18. Smooth Phase Interpolated Keying

    Science.gov (United States)

    Borah, Deva K.

    2007-01-01

    Smooth phase interpolated keying (SPIK) is an improved method of computing smooth phase-modulation waveforms for radio communication systems that convey digital information. SPIK is applicable to a variety of phase-shift-keying (PSK) modulation schemes, including quaternary PSK (QPSK), octonary PSK (8PSK), and 16PSK. In comparison with a related prior method, SPIK offers advantages of better performance and less complexity of implementation. In a PSK scheme, the underlying information waveform that one seeks to convey consists of discrete rectangular steps, but the spectral width of such a waveform is excessive for practical radio communication. Therefore, the problem is to smooth the step phase waveform in such a manner as to maintain power and bandwidth efficiency without incurring an unacceptably large error rate and without introducing undesired variations in the amplitude of the affected radio signal. Although the ideal constellation of PSK phasor points does not cause amplitude variations, filtering of the modulation waveform (in which, typically, a rectangular pulse is converted to a square-root raised cosine pulse) causes amplitude fluctuations. If a power-efficient nonlinear amplifier is used in the radio communication system, the fluctuating-amplitude signal can undergo significant spectral regrowth, thus compromising the bandwidth efficiency of the system. In the related prior method, one seeks to solve the problem in a procedure that comprises two major steps: phase-value generation and phase interpolation. SPIK follows the two-step approach of the related prior method, but the details of the steps are different. In the phase-value-generation step, the phase values of symbols in the PSK constellation are determined by a phase function that is said to be maximally smooth and that is chosen to minimize the spectral spread of the modulated signal. In this step, the constellation is divided into two groups by assigning, to information symbols, phase values

  19. Characterizing CDOM Spectral Variability Across Diverse Regions and Spectral Ranges

    Science.gov (United States)

    Grunert, Brice K.; Mouw, Colleen B.; Ciochetto, Audrey B.

    2018-01-01

    Satellite remote sensing of colored dissolved organic matter (CDOM) has focused on CDOM absorption (aCDOM) at a reference wavelength, as its magnitude provides insight into the underwater light field and large-scale biogeochemical processes. CDOM spectral slope, SCDOM, has been treated as a constant or semiconstant parameter in satellite retrievals of aCDOM despite significant regional and temporal variabilities. SCDOM and other optical metrics provide insights into CDOM composition, processing, food web dynamics, and carbon cycling. To date, much of this work relies on fluorescence techniques or aCDOM in spectral ranges unavailable to current and planned satellite sensors (e.g., global variability in SCDOM and fit deviations in the aCDOM spectra using the recently proposed Gaussian decomposition method. From this, we investigate if global variability in retrieved SCDOM and Gaussian components is significant and regionally distinct. We iteratively decreased the spectral range considered and analyzed the number, location, and magnitude of fitted Gaussian components to understand if a reduced spectral range impacts information obtained within a common spectral window. We compared the fitted slope from the Gaussian decomposition method to absorption-based indices that indicate CDOM composition to determine the ability of satellite-derived slope to inform the analysis and modeling of large-scale biogeochemical processes. Finally, we present implications of the observed variability for remote sensing of CDOM characteristics via SCDOM.

  20. Spectral Ripple Discrimination in Normal Hearing Infants

    Science.gov (United States)

    Horn, David L.; Won, Jong Ho; Rubinstein, Jay T.; Werner, Lynne A.

    2016-01-01

    Objectives Spectral resolution is a correlate of open-set speech understanding in post-lingually deaf adults as well as pre-lingually deaf children who use cochlear implants (CIs). In order to apply measures of spectral resolution to assess device efficacy in younger CI users, it is necessary to understand how spectral resolution develops in NH children. In this study, spectral ripple discrimination (SRD) was used to measure listeners’ sensitivity to a shift in phase of the spectral envelope of a broadband noise. Both resolution of peak to peak location (frequency resolution) and peak to trough intensity (across-channel intensity resolution) are required for SRD. Design SRD was measured as the highest ripple density (in ripples per octave) for which a listener could discriminate a 90 degree shift in phase of the sinusoidally-modulated amplitude spectrum. A 2X3 between subjects design was used to assess the effects of age (7-month-old infants versus adults) and ripple peak/trough “depth” (10, 13, and 20 dB) on SRD in normal hearing listeners (Experiment 1). In Experiment 2, SRD thresholds in the same age groups were compared using a task in which ripple starting phases were randomized across trials to obscure within-channel intensity cues. In Experiment 3, the randomized starting phase method was used to measure SRD as a function of age (3-month-old infants, 7-month-old infants, and young adults) and ripple depth (10 and 20 dB in repeated measures design). Results In Experiment 1, there was a significant interaction between age and ripple depth. The Infant SRDs were significantly poorer than the adult SRDs at 10 and 13 dB ripple depths but adult-like at 20 dB depth. This result is consistent with immature across-channel intensity resolution. In contrast, the trajectory of SRD as a function of depth was steeper for infants than adults suggesting that frequency resolution was better in infants than adults. However, in Experiment 2 infant performance was