Some comments on the views of Niaz, Rodriguez and Brito on Mendeleev's periodic system
Scientific Electronic Library Online (English)
Eric, Scerri.
Full Text Available Many articles have been written about the value of incorporating an understanding of history and philosophy of science into science education and this has included the teaching of chemistry. Given the immense role that the periodic table plays in chemistry it is important to be clear about a histori [...] cal and philosophical perspective on the periodic table and its possible ramifications for the way in which chemistry is presented. The article presents a critique of a paper by Niaz, Rodriguez and Brito who have addressed the relevance of historical and philosophical aspects of the periodic table in an article in which they have claimed that Mendeleev's periodic table should be regarded as a theory. In addition they have claimed that Mendeleev was a supporter of the atomic theory and have addressed some general philosophical questions concerning inductivism and the role of prediction and accommodation in the acceptance of scientific discoveries.
The Different Periodic Tables of Dmitrii Mendeleev
Laing, Michael
2008-01-01
Between 1869 and 1905 the Russian chemist Dmitrii Mendeleev published several tables with different arrangements of the chemical elements. Four of these are compared with periodic tables by Russian scientists from 1934 and 1969. The difficulties caused by the lanthanoid elements are clearly seen in the table of 1905, which satisfactorily includes…
Novelty, coherence, and Mendeleev's periodic table.
Schindler, Samuel
2014-03-01
Predictivism is the view that successful predictions of "novel" evidence carry more confirmational weight than accommodations of already known evidence. Novelty, in this context, has traditionally been conceived of as temporal novelty. However temporal predictivism has been criticized for lacking a rationale: why should the time order of theory and evidence matter? Instead, it has been proposed, novelty should be construed in terms of use-novelty, according to which evidence is novel if it was not used in the construction of a theory. Only if evidence is use-novel can it fully support the theory entailing it. As I point out in this paper, the writings of the most influential proponent of use-novelty contain a weaker and a stronger version of use-novelty. However both versions, I argue, are problematic. With regard to the appraisal of Mendeleev' periodic table, the most contentious historical case in the predictivism debate, I argue that temporal predictivism is indeed supported, although in ways not previously appreciated. On the basis of this case, I argue for a form of so-called symptomatic predictivism according to which temporally novel predictions carry more confirmational weight only insofar as they reveal the theory's presumed coherence of facts as real. PMID:24984451
Interaction properties of ytterbium with elements of Mendeleev periodic table
International Nuclear Information System (INIS)
This article presents the new data on ytterbium interaction with elements of Mendeleev periodic table. The state diagrams of ytterbium with magnesium, calcium, strontium, and barium are constructed. The state diagrams of ytterbium with Cu, Ag, Au, Zn, Cd, Hg, B,Al, Ga, In, Tl are considered.
Modification and expansion of Mendeleev's periodic table
International Nuclear Information System (INIS)
The periodic table of the chemical elements has provided guidance for the discovery of many elements since its formulation as a guiding principle 125 years ago. It has misled investigators on occasion into temporary excursions along erroneous routes to new elements. Even these tortuous paths, however, have eventually led to the correct destination. It is described, the part that the periodic table has played in the discovery of the man-made elements, especially the transuranium elements, and its possible future role. (author). 7 refs., 6 figs
Directory of Open Access Journals (Sweden)
Khazan A.
2009-07-01
Full Text Available This paper gives a survey for the methods how a possible upper limit in Mendeleev's Periodic Table can be found. It is show, only the method of hyperbolas leads to exact answering this question.
From the Mendeleev periodic table to particle physics and back to the periodic table
Energy Technology Data Exchange (ETDEWEB)
Kibler, Maurice R. [Universite de Lyon, Institut de Physique Nucleaire, Universite Lyon 1 and CNRS/IN2P3, 43 Bd du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France)
2006-11-15
We briefly describe in this paper the passage from Mendeleev's chemistry (1869) to atomic physics (in the 1900's), nuclear physics (in the 1932's) and particle physics (from 1953 to 2006). We show how the consideration of symmetries, largely used in physics since the end of the 1920's, gave rise to a new format of the periodic table in the 1970's. More specifically, this paper is concerned with the application of the group SO(4,2)xSU(2) to the periodic table of chemical elements. It is shown how the Madelung rule of the atomic shell model can be used for setting up a periodic table that can be further rationalized via the group SO(4,2)xSU(2) and some of its subgroups. Qualitative results are obtained from this nonstandard table. (author)
From the Mendeleev periodic table to particle physics and back to the periodic table
International Nuclear Information System (INIS)
We briefly describe in this paper the passage from Mendeleev's chemistry (1869) to atomic physics (in the 1900's), nuclear physics (in the 1932's) and particle physics (from 1953 to 2006). We show how the consideration of symmetries, largely used in physics since the end of the 1920's, gave rise to a new format of the periodic table in the 1970's. More specifically, this paper is concerned with the application of the group SO(4,2)xSU(2) to the periodic table of chemical elements. It is shown how the Madelung rule of the atomic shell model can be used for setting up a periodic table that can be further rationalized via the group SO(4,2)xSU(2) and some of its subgroups. Qualitative results are obtained from this nonstandard table. (author)
Kaji, Masanori
2003-05-01
The favorable and relatively rapid reception of Mendeleev's periodic table of the elements can be attributed, in part at least, to his social connections. These connections were evident in the recently organized Russian Chemical Society. In addition, Mendeleev enjoyed the support of the editorial board of the journal of the German Chemical Society. PMID:12796115
Superconductivity, antiferromagnetism and ferromagnetism in periodic table of D.I. Mendeleev
International Nuclear Information System (INIS)
Basic tendencies in the distribution of ferromagnetic (FM), antiferromagnetic (AFM) and superconductive (SC) elements in the periodic table D.I. Mendeleev are traced. FM is observed at the elements in which 3d-shell is more than half-filled (the number of 3d-electrons 6?n?8), and at the elements with 4f-shell, contained k electrons in 4f-shell, at which the sum k+n?8. Estimation of the radii of the d-, f- and p-orbitals on Slater method shown that 3d- and 4f-shells of FM are more pressing, than the ones with smaller n and k+n, and are well separated in crystal. AFM is observed at the elements, at which 3d- or 4f-shells are precisely half-filled. SC is observed in the 3d-, 4d- and 5d-elements at 1?n?x, x grows from 3 in 3d-elements to 7 in 4d- and 5d-elements, and in 7th period only at n=2 and k+n=3. Further, SC is observed at the elements, at which 3p-, 4p-, 5p- and 6p-shells contain no more than 4 electrons. In SC crystals the wave functions of external d- and p-electrons of each atom penetrate inside neighbor atoms and overlap with corresponding wave functions with smaller main quantum number than of central atom. In this case the separation of spin and charge in electron is quite possible and the charges without spin become bosons. Spins obtained magnetic moments are ordered antiparallel by two. At transfer that pair in the parallel state by magnetic field its magnetic flux from magnetic field component along of magnetic field is equal to 1 fluxon (quant of magnetic flux)
Investigating Patterns: An introduction to Mendeleev, periodicity, and the Periodic Table
Jennifer Hogan
This activity is a puzzle where students organize samples and look for patterns in order to predict properties of missing puzzle pieces. The students then relate their experience to the historical development of the Periodic Table and the ways that the Periodic Table can be used to predict the properties of the elements.
Superconductivity, antiferromagnetism and ferromagnetism in periodic table of D.I. Mendeleev
International Nuclear Information System (INIS)
Definite regularity in the distribution of ferromagnetic, antiferromagnetic and superconducting elements is observed in the periodic table starting with the 4th period. Elements with superconductivity, by which d-shells start to fill up, are at the beginning of each period; then follow antiferromagnetics and ferromagnetics (in 4th period and lanthanides), or elements without any of the three listed order types (5th period and 6th period), in which the d (f)-shells continue to fill up almost exceedingly; then again appear superconductors by filling the p-shell up to the number is equal to 4. We calculated the radii of the external d (f)- and p-orbitals and the nearest to them orbitals with the Slater method. These trends were explained by distinction of degree of division of the external d (f)- or p-orbitals of the neighboring atoms in the crystal. Largest division occurs in ferromagnetics. In antiferromagnetics it is smaller than in ferromagnetics. It is demonstrated that in the superconducting crystals the external dor p-shells approach the nucleus of neighboring atoms are much closely those for ferromagnetic or antiferromagnetic crystals. Furthermore the external d- or p-shells of some elements in the 5th and 6th periods approach the deeper shells of neighboring atoms. Hence the electron in this shell is situated in neighboring atoms in a different electric field from its own. This fact is open to speculation that the separation of spin and charge in electron, disposed on the external d- or p-orbitals, is quite possible. The charges without spin become bosons. Spins that have the magnetic moments are ordered antiparallel in pairs. Magnetic field transfers this pair in a parallel state and a magnetic flux component along of magnetic field from the pair is equal to one fluxon (the quant of the magnetic flux).
Lanthanides and actinides among other groups of elements of the D.I. Mendeleev's Periodic Table
International Nuclear Information System (INIS)
The extent to which actinides are similar to other elements of the periodic table is discussed. Actinides show certain similarity with transition metals in trends in variation of stability of the highest and lowest oxidation states with increasing atomic number. Similarity between elements of the first half of the lanthanide family and those of the second half of the actinides family is demonstrated. In the lowest oxidation states, actinides and lanthanide are analogs of alkali and alkaline-earth elements, and in the tetravalent state they start to exhibit noticeable similarity with d elements. The formation of Pu(VIII) is suggested on the basis of essentially similar volatility of oxides of Os and Ru with that of Pu. Bivalent actinides and lanthanide ions with one d electron are of particular interest. Being analogs of bivalent elements, they form various types of clusters
The slow penetration of the Mendeleev Table in the French school curricula
International Nuclear Information System (INIS)
The great influence of the Berthelot's ideas about the non existence of atoms froze the teaching of chemistry in France for quite a long time. It is only after the Second World War that the study of the atom structure appeared in school curricula. The Mendeleev periodic system that sets the relationship between chemical properties and atom structure entered the curriculum even later in 1978. The article shows that the authors of most school manuals had anticipated the change, for in 1966 all the chemistry manuals of the 6. form had a chapter dedicated to the Mendeleev table while the issue was not yet on the syllabus. (A.C.)
Geometrochemistry vs Soft Computing of Mendeleev's Brain.
Czech Academy of Sciences Publication Activity Database
Gottvald, Aleš
Brno : Brno University of Technology, 2010, s. 558-564. ISBN 978-80-214-4120-0. [Mendel 2010 - International Conference on Soft Computing /16./. Brno (CZ), 23.06.2010-25.06.2010] Institutional research plan: CEZ:AV0Z20650511 Keywords : projective geometry * Law of Mass Action * Mendeleev periodic table * brain information processing * artificial neural networks * cross-ratio * incidence structure s Subject RIV: BD - Theory of Information
Czech Academy of Sciences Publication Activity Database
Štrbá?ová, So?a
Oxford : Oxford University Press, 2015 - (Kaji, M.; Kragh, H.; Pallo, G.), s. 121-149 ISBN 978-0-19-020007-7 R&D Projects: GA AV ?R IAAX00630801 Institutional support: RVO:68378114 Keywords : D. I. Mendeleev * B. Brauner * history of the periodic system of elements Subject RIV: AB - History
The role of the Czech chemists in reception and dissemination of the periodic system in Europe.
Czech Academy of Sciences Publication Activity Database
Štrbá?ová, So?a
Budapest : MKE, 2009. s. 40. ISBN 978-963-9319-96-7. [International conference on the history of chemistry. Consumers and experts. The uses of chemistry (and alchemy ) /7./. 02.08.2009-05.08.2009, Sopron] Institutional research plan: CEZ:AV0Z80630520 Keywords : D.I. Mendeleev * B. Brauner * periodic system of elements * history of chemistry * history of Czech chemistry Subject RIV: AB - History
Directory of Open Access Journals (Sweden)
Raos, N.
2011-12-01
Full Text Available The Croatian (Yugoslav Academy of Sciences and Arts was the first academy to elect D. I. Mendeleev as its honorary member (1882, whereas the periodic table of the elements has been taught regularly at the Zagreb University since 1888. The early interest of Croatian chemists in the periodic table should be attributed primarily to their pan-Slavic attitude, particularly as proof that Slavic people were able to produce "their own Newtons" (M. V. Lomonosov and D. I. Mendeleev. Such enthusiastic views, however, did not help in analyzing the contribution of Mendeleev and other scientists to the discovery and development of the periodic table of the elements.
Chernykh, Andrey; Astafurova, Ekaterina; Korneva, Maria; Egorova, Alena; Redko, Anton; Glebovsky, Vladimir
2014-05-01
The work was performed under Russian Federation State Geological mapping at a scale of 1:1 000 000 and UNCLOS programs. The study area is located between 76N-84N and 156E-168W and covers the Mendeleev Ridge, adjacent Podvodnikov, Mendeleev, Chukchi Basins and northern part of the East-Siberian Sea shelf. It is characterized by very poor magnetic and gravity data coverage. Majority of airborne magnetic and on-ice gravity surveys were carried out in the region about 40 years ago and have low spatial resolution and poor navigation. Seismic data collected earlier in the study area are presented by sparse lines of historical seismic reflection soundings and by results of deep seismic refraction and reflection observations along several geotransects. Hence, conclusions concerning tectonic structure and spatial relation of the Mendeleev Ridge with adjacent geological structures up to present day remain speculative. Joint analysis of recent seismic reflection and refraction data collected during Russian expeditions «Arctic-2011» and «Arctic-2012» with mentioned above geophysical information allowed to clarify the contours of geological structures in the study area and reveal some new peculiarities of their tectonic pattern. Particularly complex tectonic structure of the Mendeleev Ridge, changing from it's southern to the northern part and represented by two main systems of tectonic displacements is discovered. The first fault system comprises horsts/graben-bounding faults oriented preferably in N-S direction. The second system is presented by faults of NW-SE direction disturbing the first one. In the southern part of the Mendeleev Ridge such faults are the strike-slip faults with small horizontal displacements. Starting from the central part of the ridge and further to the north, displacements along strike-slip faults become progressively more pronounced and have sinistral character. In the northern part of the ridge a pull-apart structures are recognized which presumably correspond to the transitional shear zone between the Mendeleev and the Alpha ridges. Mentioned above features indicate that existed earlier as a single structure the Alpha-Mendeleev Ridge was exposed to transtension. As a result it was separated later by the shear zone on two ridges which moved from each other with forming the system of NW-SE left-lateral strike-slip (oblique-slip) faults. Some more details and speculations concerning the tectonic pattern of the Mendeleev Ridge and adjacent structures will be offered in presentation.
Superheavy elements in D I Mendeleev's Periodic Table
International Nuclear Information System (INIS)
The results on the synthesis of new superheavy elements, synthesized in complete fusion reactions of 48Ca ions with actinide targets, are summarized and analyzed. The perspectives for the synthesis of element 117, as well as of elements with Z?118 are also considered.
Periodic systems filtering and control
Bittanti, Sergio
2008-01-01
This book offers a comprehensive treatment of the theory of periodic systems, including the problems of filtering and control. It covers an array of topics, presenting an overview of the field and focusing on discrete-time signals and systems..
International Nuclear Information System (INIS)
By the methods of PMR and infrared-spectroscopy studied are the tungstate hydrates of Mg, Li, Cd, Al, Ge, In, Ti, Ln, Hf. The PMR spectra have been taken for air-dry and partly hydrated samples in the temperature range from 93 to 295 K. In tungstate hydrates of the 2nd and 4th groups found are the distorted moleculas of H2O with the intermolecular interproton distances different from 1.53 A, namely, increased up to 2.69 A and decreased to 1.38 A. Determined is the quantitative content of OH- groups and H2O moleculas, with different interproton distance. A formula content of the compounds studied is proposed. In tungstates of the 3d group the distorted moleculas are found only in compounds with H-/Me2O distortion is confirmed by the data of infrared spectr. The process of dehydration of distorted H2O moleculas is studied
Large minimal period orbits of periodic autonomous systems
Campos, Juan; Tarallo, Massimo
2004-01-01
We prove the existence of periodic orbits with minimal period greater than any prescribed number for a natural Lagrangian autonomous system in several variables that is analytic and periodic in each variable and whose potential is nonconstant. Work supported by Acción Integrada Italia-España HI2000-0112, Azione Integrata Italia-Spagna IT-117, MCYT BFM2002-01308, Spain.
A Periodic Lotka-Volterra System
Tsvetkov, D
1996-01-01
In this paper periodic time-dependent Lotka-Volterra systems are considered. It is shown that such a system has positive periodic solutions. It is done without constructive conditions over the period and the parameters.
Elkina, D.
2014-12-01
Nowadays the Arctic Ocean is an area of higher scientific interest. Investigation of composition, genesis, sources and source areas of marine sediments is necessary for a gain of geological knowledge and geo-engineering development of the region. One should note that the dating issue in the Arctic Ocean is a challenge by itself. However, magnetostratigraphy can offer a powerful stratigraphic tool applying to marine sediments here. The 6-meters length core was retrieved from the Mendeleev Ridge in 2012 and subjected to paleomagnetic studies. The examined core was revealed to dominate by normal polarity up to 123 cm below seafloor (cmbsf) and assigned there to the Brunhes polarity chron of the geomagnetic field (0.78 Ma). Then prevalence of reverse polarity persists up to 394-397 cmbsf, assigned to Matuyama age, and short positive intervals are believed to be subchrons of normal polarity. Change from reverse to normal polarity at 394-397 cmbsf is considered as the Matuyama - Gauss (2.58 Ma) boundary and is traced up to 530-531 cmbsf including one short reversal. After this depth a drop back to reverse polarity is ascribed to the beginning of the Gilbert polarity chron (3.58 Ma). The resultant magnetostratigraphy is presented on Figure 1. The stepwise alternating field demagnetization and demagnetization by heating were performed to remove viscous overprints and then to define component magnetization directions. Spikes of natural remanent magnetization intensity and magnetic susceptibility are discovered near almost all assigned chron boundaries, and it may act as an independent factor for determination of polarity boundaries. Anisotropy of magnetic susceptibility is also considered in order to find out additional peculiarities of the sedimentation. The relative abundance of shallow inclinations at least implies the existence of secondary processes, which may have altered the paleomagnetic record. The mean sedimentation rates on the Mendeleev Ridge do not exceed 1.58 mm kyr-1 for 3.58 Ma and therefore represent the sedimentation rates as low for the whole Quaternary period and also for the part of the Pliocene epoch.
Positive periodic solutions of delayed periodic Lotka-Volterra systems
Energy Technology Data Exchange (ETDEWEB)
Lin Wei [Laboratory of Nonlinear Mathematics Science, Institute of Mathematics, Fudan University, Shanghai 200433 (China)]. E-mail: weilin@fudan.edu.cn; Chen Tianping [Laboratory of Nonlinear Mathematics Science, Institute of Mathematics, Fudan University, Shanghai 200433 (China)]. E-mail: tchen@fudan.edu.cn
2005-01-17
In this Letter, for a general class of delayed periodic Lotka-Volterra systems, we prove some new results on the existence of positive periodic solutions by Schauder's fixed point theorem. The global asymptotical stability of positive periodic solutions is discussed further, and conditions for exponential convergence are given. The conditions we obtained are weaker than the previously known ones and can be easily reduced to several special cases.
Positive periodic solutions of delayed periodic Lotka-Volterra systems
International Nuclear Information System (INIS)
In this Letter, for a general class of delayed periodic Lotka-Volterra systems, we prove some new results on the existence of positive periodic solutions by Schauder's fixed point theorem. The global asymptotical stability of positive periodic solutions is discussed further, and conditions for exponential convergence are given. The conditions we obtained are weaker than the previously known ones and can be easily reduced to several special cases
Transgressive Legacies of Memory : The Concept of Techné in Primo Levi's 'Periodic Table'
Botez, Catalina
2012-01-01
This chapter is looking at Italian writer Primo Levi’s most original work Il sistema periodico (1975), translated in English as The Periodic Table (1995), which engages in a fascinating manner with the overlapping spheres of (auto)biography, memoir, poetical myth and fiction. This compelling literary hybrid mingles landmarks of personal pre- and post-WWII experience with significant fictitious tales, mapped around elements of Mendeleev’s periodic table.The concept that binds all twenty one st...
Design of periodic beam-transport systems
International Nuclear Information System (INIS)
Periodic beam-transport systems have several advantages including insensitivity to errors, minimum magnet apertures, and use of standardized components. A simple procedure is given for the design of modules, with and without bending magnets, that have the same matched beam properties. These modules can be combined in certain ways to produce systems that are achromatic and require a minimum number of matching elements
Localized States in Periodically Forced Systems
Gandhi, Punit; Knobloch, Edgar; Beaume, Cédric
2015-01-01
The theory of stationary spatially localized patterns in dissipative systems driven by time-independent forcing is well developed. With time-periodic forcing, related but time-dependent structures may result. These may consist of breathing localized patterns, or states that grow for part of the cycle via nucleation of new wavelengths of the pattern followed by wavelength annihilation during the remainder of the cycle. These two competing processes lead to a complex phase diagram whose structure is a consequence of a series of resonances between the nucleation time and the forcing period. The resulting diagram is computed for the periodically forced quadratic-cubic Swift-Hohenberg equation, and its details are interpreted in terms of the properties of the depinning transition for the fronts bounding the localized state on either side. The results are expected to shed light on localized states in a large variety of periodically driven systems.
Orbital stability for the periodic Zakharov system
International Nuclear Information System (INIS)
In this work we prove the existence of a smooth curve of periodic travelling wave solutions of dnoidal type for the one-dimensional Zakharov system. We also show that this type of solution is orbitally stable by periodic perturbations of the same wavelength as the underlying wave. As a consequence of our stability approach, we give an analysis of the stability parameters. We also give other proof of the orbital stability of the well-known solitary wave profiles. We hope that the techniques employed may be of further use in the study of the stability of periodic travelling wave solutions for other nonlinear evolution equations
Quantization of a Periodic Gravitational System
International Nuclear Information System (INIS)
We quantize a periodic gravitational system with a generalized covariant rule of Wilson-Sommerfeld type, for both special and general relativity theories. The result is a very interesting quantization rule of mass, which have similar shape to Dirac's charge quantization
On Periodic Maintenance of a Coherent System
Directory of Open Access Journals (Sweden)
G Chaudhuri
2015-07-01
Full Text Available In this paper, we study a coherent system that has periodic maintenance performed at regular intervals. The exact analytical expressions are obtained for some important maintenance performance measures such as mean time between failures, average availability and mean fractional dead time. The CHA algorithm is used to do the relevant calculations. Some s-coherent structures viz., series, parallel, 2-out-of-3:G and a fire-detector system are considered to illustrate the method.
Scaling Concepts in Periodically Modulated Noisy Systems
Vilar, J. M. G. (José M. G.), 1972-; Rubí, J. M.
1997-01-01
We show that scaling arguments are very useful to analyze the dynamics of periodically modulated noisy systems. Information about the behavior of the relevant quantities, such as the signal-to-noise ratio, upon variations of the noise level, can be obtained by analyzing the symmetries and invariances of the system. In this way, it is possible to predict diverse physical manifestations of the cooperative behavior between noise and input signal, as for instance stochastic reso...
Periodic inspections of the primary system
International Nuclear Information System (INIS)
An impression is given of the inspection techniques, preparations and background for periodic examinations of the primary system of the Dodewaard Nuclear Reactor over the past 10 years. Unfortunately reliable integral inspection techniques to enable 'listening-in' to developing faults, are not yet available. Until they are, inspections will continue to be executed from a distance using different continuous methods, often under water and with a shortage of space and in the presence of ionising radiations. (C.F.)
Onsager Coefficients in Periodically Driven Systems
Proesmans, Karel; Van den Broeck, Christian
2015-08-01
We evaluate the Onsager matrix for a system under time-periodic driving by considering all its Fourier components. By application of the second law, we prove that all the fluxes converge to zero in the limit of zero dissipation. Reversible efficiency can never be reached at finite power. The implication for an Onsager matrix, describing reduced fluxes, is that its determinant has to vanish. In the particular case of only two fluxes, the corresponding Onsager matrix becomes symmetric.
Periodic Solutions for Highly Nonlinear Oscillation Systems
DEFF Research Database (Denmark)
Ghadimi, M; Barari, Amin
2012-01-01
In this paper, Frequency-Amplitude Formulation is used to analyze the periodic behavior of tapered beam as well as two complex nonlinear systems. Many engineering structures, such as offshore foundations, oil platform supports, tower structures and moving arms, are modeled as tapered beams. The results obtained are compared with Variational Iteration Method (VIM) and other analytical methods as well as time marching solution. The results given show the effectiveness and accuracy of the proposed techniques.
An Application-Oriented Periodic Table of the Elements.
Bouma, J.
1989-01-01
A brief history of several of the early forms of the periodic table of the elements are discussed including those of Mendeleev, Meyer, Hubbard, Gmelin, Von Antropoff, and Strong. A more every-day-life form of the table is presented. (CW)
On periodic orbits in discrete-time cascade systems
Directory of Open Access Journals (Sweden)
Xiao-Song Yang
2006-12-01
Full Text Available We present some results on existence, minimum period, number of periodic orbits, and stability of periodic orbits in discrete-time cascade systems. Some examples are presented to illustrate these results.
Periodic solutions of a forced system with hysteresis.
Drew, J. H.
1972-01-01
Hysteresis damping arising in an oscillatory system due to the phenomenon of slip damping analyzed by Goodman and Klumpp (1956) is considered. An idealized physical model is proposed, and the existence of certain periodic motions is investigated in a system with small forcing which are near the largest periodic motion in a corresponding unforced system. Periodic solutions of the forced system are obtained.-
Ortiz, J. D.; Polyak, L.; Adler, R.; Jakobsson, M.; Darby, D.
2007-12-01
During the 2005 Healy-Oden Trans-Arctic Expedition (HOTRAX), core HLY0503-JPC08 was raised from the Mendeleev Ridge at the modern junction of the Beaufort Gyre and the Transpolar Drift. This core with sedimentation rates estimated on the order of 2 cm/ka is well situated to sample variations in sedimentation, and thus circulation patterns during the Quaternary. Some characteristic features such as a distinctive change in lithology and prominent IRD layers provide the basis for correlation with previously developed stratigraphies. This overall correlation is confirmed by 1 cm post-cruise diffuse spectral reflectance measurements generated using a Minolta CM-2600d spectrophotometer. Downcore analysis of principle components extracted from the DSR data indicate an inverse correlation between smectite-chlorite which reaches maxima during interglacial/interstadial intervals when sediment Mn is also high, and illite and goethite which reach maxima during glacial intervals when sediment Mn is low. These glacial-interglacial cycles are also evident in elemental composition measured using a handheld, Innov-X Alpha series XRF analyzer which we employ on Arctic sediment for the first time. Estimates of sediment Mn content inferred by diffuse spectral reflectance agree well with XRF based measurements. We observe three distinct end-members based on physical properties and elemental composition. Low density, fine- grained, glacial sediment exhibit low Mn, low Sr, and high Rb values, and thus a high Rb/Sr ratio. Moderately sandy interglacial sediment exhibits high Mn, high Sr, and low Rb values, while sediment from the transitions in to and out of glacial periods are marked by prominent spikes in density, coarse grains, and Zr concentration. Elevated Rb/Sr ratios during glacial periods may result from the re-suspension of fine-grained sediment previously deposited on the outer shelf during higher sea level, and/or by discharge from proglacial lakes. The increase in grain-size accompanied by lows in the Rb/Sr ratio during interglacial/interstadial conditions provides a proxy for fluvial sediment transport and sea-ice rafting from inner shelf environments. Zr spikes mark IRD events corresponding to ice-sheet instabilities. Because the Zr spikes are generally not associated with elevated Ca, a proxy for detrital carbonate, we infer that these spikes represent predominantly iceberg-rafted sediment of Eurasian origin, whereas three distinct Ca maxima indicate prominent iceberg events originating from the Laurentide ice sheet.
Scientific Electronic Library Online (English)
Helena S. A., Leite; Paulo A., Porto.
2015-05-01
Full Text Available [...] Abstract in english The aim of this paper was to analyze the historical approaches to the periodic table in general chemistry textbooks used in Brazilian universities in the twentieth century. Textbooks were qualitatively analyzed according to the following criteria: position of the discussion about the periodic table [...] in the book; presence or absence of a specific chapter on the subject; presentation of attempts to classify chemical elements before Mendeleev; presentation of the construction process of the periodic table by Mendeleev; identification of problems in the original table; discussion of Mendeleev's predictions about unknown elements; organization of the periodic table; periodic properties presented and discussed; and the enunciation of the periodic law. The analysis revealed different approaches at specific periods of the twentieth century, from more descriptive approaches to emphasis on attempts to explain the periodic table in terms of atomic orbitals. These changes point to different ways of understanding chemistry during the period studied.
International Nuclear Information System (INIS)
A two-species periodic competition Lotka-Volterra system with time delay and diffusion is investigated. Some sufficient conditions of the existence of positive periodic solution are established for the system by using the continuation theorem of coincidence degree theory
Energy Technology Data Exchange (ETDEWEB)
Sun Wen [School of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China); Chen Shihua [School of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China)]. E-mail: shcheng@whu.edu.cn; Hong Zhiming [School of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China); Wang Changping [Department of Mathematics and Statistics, Dalhousie University, Halifax, NS, B3H 3J5 (Canada)
2007-08-15
A two-species periodic competition Lotka-Volterra system with time delay and diffusion is investigated. Some sufficient conditions of the existence of positive periodic solution are established for the system by using the continuation theorem of coincidence degree theory.
Scientific Electronic Library Online (English)
Mario, Tolentino; Romeu C., Rocha-Filho; Aécio Pereira, Chagas.
1997-02-01
Full Text Available [...] Abstract in english A history of the periodic table of the elements is presented, from the first tentative classifications, passing through Meyer and Mendeleev, up to recent speculations on super-heavy elements still to be synthesized. Many of the discussions and discoveries related to chemical elements and their prope [...] r periodic classification are also presented.
Directory of Open Access Journals (Sweden)
Mario Tolentino
1997-02-01
Full Text Available A history of the periodic table of the elements is presented, from the first tentative classifications, passing through Meyer and Mendeleev, up to recent speculations on super-heavy elements still to be synthesized. Many of the discussions and discoveries related to chemical elements and their proper periodic classification are also presented.
Periodic Table of the Elements in the Perspective of Artificial Neural Networks
Lemes, Mauricio R.; Dal Pino, Arnaldo
2011-01-01
Although several chemical elements were not known by end of the 19th century, Mendeleev came up with an astonishing achievement, the periodic table of elements. He was not only able to predict the existence of (then) new elements, but also to provide accurate estimates of their chemical and physical properties. This is a profound example of the…
Dynamical system theory of periodically collapsing bubbles
Yukalov, V I; Sornette, D
2015-01-01
We propose a reduced form set of two coupled continuous time equations linking the price of a representative asset and the price of a bond, the later quantifying the cost of borrowing. The feedbacks between asset prices and bonds are mediated by the dependence of their "fundamental values" on past asset prices and bond themselves. The obtained nonlinear self-referencing price dynamics can induce, in a completely objective deterministic way, the appearance of periodically exploding bubbles ending in crashes. Technically, the periodically explosive bubbles arise due to the proximity of two types of bifurcations as a function of the two key control parameters $b$ and $g$, which represent, respectively, the sensitivity of the fundamental asset price on past asset and bond prices and of the fundamental bond price on past asset prices. One is a Hopf bifurcation, when a stable focus transforms into an unstable focus and a limit cycle appears. The other is a rather unusual bifurcation, when a stable node and a saddle...
Effective Hamiltonian approach to periodically perturbed quantum optical systems
International Nuclear Information System (INIS)
We apply the method of Lie-type transformations to Floquet Hamiltonians for periodically perturbed quantum systems. Some typical examples of driven quantum systems are considered in the framework of this approach and corresponding effective time dependent Hamiltonians are found
Analytical Hartree-Fock gradients for periodic systems
Doll, K.; SAUNDERS, VR; Harrison, NM
2000-01-01
We present the theory of analytical Hartree-Fock gradients for periodic systems as implemented in the code CRYSTAL. We demonstrate how derivatives of the integrals can be computed with the McMurchie-Davidson algorithm. Highly accurate gradients with respect to nuclear coordinates are obtained for systems periodic in 0,1,2 or 3 dimensions.
Dynamical Systems and Traveling Waves in Almost Periodic Structures
Shen, Wenxian
2001-01-01
The paper is devoted to the study of traveling waves in almost periodic structures by applying dynamical system theory. Motivated by the fact that almost automorphic dynamics often exists (though almost periodic dynamics may not) in scalar almost periodic ODEs and parabolic PDEs, we introduce a definition of almost automorphic traveling waves and investigate the existence of such traveling waves in general almost periodic structures. In the author's earlier work, a notion of almost periodic traveling wave solution is introduced. Roughly, a solution is an almost automorphic (almost periodic) traveling wave solution if its propagating profile and speed are almost automorphic (almost periodic) functions. Our basic point of view is that traveling wave solutions are the limits of certain wave-like solutions. We therefore study the existence of almost automorphic traveling wave solutions through the long time behavior of wave-like solutions. We first investigate the existence of wave-like solutions. Then by utilizing dynamical system theory, we explore the “convergence” of wave-like solutions to alsmot automorphic (almost periodic) traveling wave solutions. Besides, based on the arguments established in the author's earlier work on bistable equations, we show the stability, uniqueness, and almost periodicity of almost automorphic traveling wave solutions in almost periodic equations of multi-stable type. Applying the general theory developed in the paper to almost periodic equations of KPP type, we show the existence of a family of almost automorphic traveling waves under some conditions.
Computer-based Periodicals Management System in SAC Library
Directory of Open Access Journals (Sweden)
D.R. Patel,
1995-05-01
Full Text Available The paper discusses the efforts made for a Periodicals Management System developed and designed for implementation in SAC Library, using DBASE III software. It briefly describes the computer programmes in PMS and highlights the present system which is implemented by using 'LIBSYS', a comprehensive library software package and a multi-user system on Pentium system, under Unix environment.
Periodic solutions of nonautonomous differential systems modeling obesity population
Energy Technology Data Exchange (ETDEWEB)
Arenas, Abraham J. [Departamento de Matematicas y Estadistica, Universidad de Cordoba Monteria (Colombia)], E-mail: aarenas@sinu.unicordoba.edu.co; Gonzalez-Parra, Gilberto [Departamento de Calculo, Universidad de los Andes, Merida (Venezuela, Bolivarian Republic of)], E-mail: gcarlos@ula.ve; Jodar, Lucas [Instituto de Matematica Multidisciplinar, Universidad Politecnica de Valencia Edificio 8G, 2o, 46022 Valencia (Spain)], E-mail: ljodar@imm.upv.es
2009-10-30
In this paper we study the periodic behaviour of the solutions of a nonautonomous model for obesity population. The mathematical model represented by a nonautonomous system of nonlinear ordinary differential equations is used to model the dynamics of obese populations. Numerical simulations suggest periodic behaviour of subpopulations solutions. Sufficient conditions which guarantee the existence of a periodic positive solution are obtained using a continuation theorem based on coincidence degree theory.
Periodic orbits of Hamiltonian systems: Applications to perturbed Kepler problems
International Nuclear Information System (INIS)
We provide for a class of Hamiltonian systems in the action–angle variables sufficient conditions for showing the existence of periodic orbits. We expand this result to the study of the existence of periodic orbits of perturbed spatial Keplerian Hamiltonians with axial symmetry. Finally, we apply these general results for finding periodic orbits of the Matese–Whitman Hamiltonian, of the spatial anisotropic Hamiltonian and of the spatial generalized van der Waals Hamiltonian
Periodic solutions of nonautonomous differential systems modeling obesity population
International Nuclear Information System (INIS)
In this paper we study the periodic behaviour of the solutions of a nonautonomous model for obesity population. The mathematical model represented by a nonautonomous system of nonlinear ordinary differential equations is used to model the dynamics of obese populations. Numerical simulations suggest periodic behaviour of subpopulations solutions. Sufficient conditions which guarantee the existence of a periodic positive solution are obtained using a continuation theorem based on coincidence degree theory.
Equilibrium states of generic quantum systems subject to periodic driving.
Lazarides, Achilleas; Das, Arnab; Moessner, Roderich
2014-07-01
When a closed quantum system is driven periodically with period T, it approaches a periodic state synchronized with the drive in which any local observable measured stroboscopically approaches a steady value. For integrable systems, the resulting behavior is captured by a periodic version of a generalized Gibbs ensemble. By contrast, here we show that for generic nonintegrable interacting systems, local observables become independent of the initial state entirely. Essentially, this happens because Floquet eigenstates of the driven system at quasienergy ?(?) consist of a mixture of the exponentially many eigenstates of the undriven Hamiltonian, which are thus drawn from the entire extensive undriven spectrum. This is a form of equilibration which depends only on the Hilbert space of the undriven system and not on any details of its Hamiltonian. PMID:25122254
The periodic system of chemical elements: old and new developments
International Nuclear Information System (INIS)
Some historical facts about the construction of a periodic system of chemical elements are reviewed. The Madelung rule is used to generate an unusual format for the periodic table. Following the work of Byakov, Kulakov, Rumer and Fet, such a format is further refined on the basis of a chain of groups starting with SU(2)xS0(4.2)
Jumping particle model. Period doubling cascade in an experimental system
Piera?ski, P.
1983-01-01
An experimental model of a modification of the Fermi acceleration problem is described. Evidence is presented for three consecutive bifurcations on the period doubling route of the system from regular to chaotic behaviour.
Implementation of analytical Hartree-Fock gradients for periodic systems
Doll, K.
2001-01-01
We describe the implementation of analytical Hartree-Fock gradients for periodic systems in the code CRYSTAL, emphasizing the technical aspects of this task. The code is now capable of calculating analytical derivatives with respect to nuclear coordinates for systems periodic in 0, 1, 2 and 3 dimensions (i.e. molecules, polymers, slabs and solids). Both closed-shell restricted and unrestricted Hartree-Fock gradients have been implemented. A comparison with numerical derivati...
Periodic Solutions for a Discrete Mutual System with Delays
Directory of Open Access Journals (Sweden)
CHEN Da-xue
2012-01-01
Full Text Available In this paper, a discrete-time mutual system * is considered. By using coincidence degree and the related continuation the orem as well as prior estimates, easily sufficient conditions for the existence of positive periodic solutions are obtained,* if the following conditi * hold, then system has at least an w periodic solution. Our results are important complement to earlier results in the literature.(* Indicates a formula, please see the full text
Inverse crystallization if Abrikosov vortex system at periodic pinning
Zyubin, M V; Kashurnikov, V A
2002-01-01
The vortex system in the quasi-two-dimensional HTSC plate is considered in the case of the periodic pinning. The M(H) magnetization curves by various values of the external magnetic field and different temperatures are calculated through the Monte Carlo method. It is shown that in the case of the periodic pinning the crystallization of the vortex system is possible by the temperature increase. A number of peculiarities conditioned by the impact of the pinning centers periodic lattice are identified on the magnetization curves. The pictures of the vortex distribution corresponding to various points on the M(H) curve are obtained
Positive periodic solutions of periodic neutral Lotka-Volterra system with distributed delays
International Nuclear Information System (INIS)
By using a fixed point theorem of strict-set-contraction, some criteria are established for the existence of positive periodic solutions of the following periodic neutral Lotka-Volterra system with distributed delays (dxi(t))/(dt) =xi(t)[ai(t)-?j=1nbij(t)?-Tij0Kij(?)xj( t+?)d?-?j=1ncij(t)?-Tij0Kij(?) xj'(t+?)d?],i=1,2,...,n, where ai,bij,cij element of C(R,R+) (i, j = 1, 2, ..., n) are ?-periodic functions, Tij,Tij element of (0,?) (i, j = 1, 2, ..., n) and Kij,Kij element of (R,R+) satisfying ?-Tij0Kij(?)d?=1,?-Tij0Kij(?)d?=1, i, j = 1, 2, ..., n
Srivastava, S. P.; Varma, H.; Macnab, R.
2005-12-01
The land masses surrounding the Arctic Ocean feature several submerged prolongations into the deep central basin. These range in size from enormous i.e. the broad continental shelves off northern Russia and Scandinavia, to small i.e. the Yermak Plateau and the Morris Jesup Rise which flank Fram Strait. Lying between these extremes on the size scale are the Chukchi Borderlands and the Lomonosov, Alpha, and Mendeleev Ridges. At either end of the scale, the prolongations appear to satisfy the Test of Appurtenance in UNCLOS Article 76, where they qualify as components of outer continental shelves. In the middle of the scale, it is generally agreed that the Chukchi Borderlands satisfy the Test of Appurtenance, but the Lomonosov, Alpha, and Mendeleev Ridges are perceived by some as problematic. While the continental composition of the Lomonosov Ridge is generally acknowledged, the structural and tectonic relationships between its extremities and the adjacent continental margins are poorly understood. Meanwhile, the origin and history of the Alpha and Mendeleev Ridges remain shrouded because of the difficulty of undertaking systematic mapping and sampling that would reveal their ages and geological makeups, and shed light on their marginal junctions. There can be little doubt that the nature and emplacement of the Lomonosov, Alpha, and Mendeleev Ridges are related to the tectonic processes that accompanied the creation of the Arctic Ocean. An understanding of those processes would help establish a geological and historic framework for interpreting the sparse knowledge that is available for the three Ridges. This presentation will consider tectonic scenarios that could account for early stages in the development of the Lomonosov, Alpha, and Mendeleev Ridges, and in the process seek to dispel uncertainties concerning their linkages to the adjacent continental margins. Until further research leads to broad general agreement concerning the answers to such questions, it would seem premature to apply the Test of Appurtenance to these features.
Phase control of resonant systems: Interference, chaos and high periodicity
Greenman, J.V.; Pasour, V.B.
2011-01-01
Abstract Much progress has been made in understanding the effect of periodic forcing on epidemiological and ecological systems when that forcing acts on just one part of the system. Much less is known about situations in which several parts of the system are affected. In this case the interaction between the impacts of the different forcing components can lead to reinforcement of system responses or to their interference. This interference phenomenon is significant if some forcing ...
Statistical mechanics of time-periodic quantum systems
Wustmann, Waltraut
2010-01-01
The asymptotic state of a quantum system, which is in contact with a heat bath, is strongly disturbed by a time-periodic driving in comparison to a time-independent system. In this thesis an extensive picture of the asymptotic state of time-periodic quantum systems is drawn by relating it to the structure of the corresponding classical phase space. To this end the occupation probabilities of the Floquet states are analyzed with respect to their semiclassical property of being either regular o...
The distribution of period ratios in Kepler planetary systems
Steffen, Jason H.; Hwang, Jason A.
2015-01-01
Kepler's multi-planet systems are a valuable tool to understand the architectures and dynamics of the inner parts of planetary systems. I present an analysis of the distribution of orbital period ratios from candidate systems identified in the Quarter 8 catalog (Burke et al. 2014). This distribution is corrected for the effects of geometric transit probabilities and the completeness of the data reduction pipeline. We find that the distribution of period ratios falls as a power law with exponent -1.26 ± 0.05. We also identify a new, statistically significant feature near a period ratio of 2.2. These observations may provide insights into the formation and evolution of these systems.
Stabilization for a Periodic Predator-Prey System
Carmen Oana Tarniceriu; Sebastian Ani?a
2008-01-01
Ã¯Â»Â¿A reaction-diffusion system modelling a predator-prey system in a periodic environment is considered. We are concerned in stabilization to zero of one of the components of the solution, via an internal control acting on a small subdomain, and in the preservation of the nonnegativity of both components.
A nondestructive characterization system of periodically poled crystals
Chen, Huaixi; Zhou, Huang; Chen, Liyuan; Zou, Xiaolin; Miao, Long; Feng, Xinkai; Li, Guangwei; Liang, Wanguo
2015-08-01
Periodically poled crystals are widely used as SHG, DFG, SFG, OPO and THz generation, and there is a broad application prospect in some areas such as the laser display, optical fiber communication, atmospheric exploration and military confrontation. At present, to get the parameters of periodically poled crystals, like duty ratio, the main method is chemical etching of the samples. In this paper, we present a nondestructive characterization system of periodically poled crystals. When we apply a proper high voltage on both sides of the periodically poled crystal, the refractive index difference of positive and negative domain will be increased and we can observe a clear domain pattern by the a microscope so as to obtain general information. Then a single frequency laser is prepared to radiate on +z surface of the periodically poled crystal, we can get some orders of diffraction according to diffraction optics principle. Finally, we can measure the parameters such as period, duty ratio by use of numerical analysis. The testing sample size of this system can be up to 60mm, The accuracy of the testing period can be 0.1?m, and the measurement range of duty ratio is 20%-50%.
Periodic Orbit Quantization of Mixed Regular Chaotic Systems
Main, J
1999-01-01
A general technique for the periodic orbit quantization of systems with near-integrable to mixed regular-chaotic dynamics is introduced. A small set of periodic orbits is sufficient for the construction of the semiclassical recurrence function up to, in principle, infinite length. As in our recent work the recurrence signal is inverted by means of a high resolution spectral analyzer (harmonic inversion) to obtain the semiclassical eigenenergies. The method is demonstrated for the hydrogen atom in a magnetic field. To our knowledge this is the first successful application of periodic orbit quantization in the deep mixed regular-chaotic regime.
Development of Seismic Isolation Systems Using Periodic Materials
Energy Technology Data Exchange (ETDEWEB)
Yan, Yiqun [Univ. of Houston, Houston, TX (United States); Mo, Yi-Lung [Univ. of Houston, Houston, TX (United States); Menq, Farn-Yuh [Univ. of Texas, Austin, TX (United States); Stokoe, II, Kenneth H. [Univ. of Texas, Austin, TX (United States); Perkins, Judy [Prairie View A & M University, Prairie View, TX (United States); Tang, Yu [Argonne National Lab. (ANL), Argonne, IL (United States)
2014-12-10
Advanced fast nuclear power plants and small modular fast reactors are composed of thin-walled structures such as pipes; as a result, they do not have sufficient inherent strength to resist seismic loads. Seismic isolation, therefore, is an effective solution for mitigating earthquake hazards for these types of structures. Base isolation, on which numerous studies have been conducted, is a well-defined structure protection system against earthquakes. In conventional isolators, such as high-damping rubber bearings, lead-rubber bearings, and friction pendulum bearings, large relative displacements occur between upper structures and foundations. Only isolation in a horizontal direction is provided; these features are not desirable for the piping systems. The concept of periodic materials, based on the theory of solid-state physics, can be applied to earthquake engineering. The periodic material is a material that possesses distinct characteristics that prevent waves with certain frequencies from being transmitted through it; therefore, this material can be used in structural foundations to block unwanted seismic waves with certain frequencies. The frequency band of periodic material that can filter out waves is called the band gap, and the structural foundation made of periodic material is referred to as the periodic foundation. The design of a nuclear power plant, therefore, can be unified around the desirable feature of a periodic foundation, while the continuous maintenance of the structure is not needed. In this research project, three different types of periodic foundations were studied: one-dimensional, two-dimensional, and three-dimensional. The basic theories of periodic foundations are introduced first to find the band gaps; then the finite element methods are used, to perform parametric analysis, and obtain attenuation zones; finally, experimental programs are conducted, and the test data are analyzed to verify the theory. This procedure shows that the periodic foundation is a promising and effective way to mitigate structural damage caused by earthquake excitation.
National Oceanic and Atmospheric Administration, Department of Commerce — This is an archive of data of 47 distinct XBT casts taken at 41 locations in the Mendeleev Ridge and Chukchi Borderland region of the Arctic between 22nd August and...
Phase control of resonant systems: interference, chaos and high periodicity.
Greenman, J V; Pasour, V B
2011-06-01
Much progress has been made in understanding the effect of periodic forcing on epidemiological and ecological systems when that forcing acts on just one part of the system. Much less is known about situations in which several parts of the system are affected. In this case the interaction between the impacts of the different forcing components can lead to reinforcement of system responses or to their interference. This interference phenomenon is significant if some forcing components are anthropogenic for then management might be able to exercise sufficient control to bring about suppression of undesirable aspects of the forcing, for example resonant amplification and the problems this can cause. We set out the algebraic theory when forcing is weak and illustrate by example what can happen when forcing is strong enough to create subharmonics and chaotic states. Phase is the key control variable that can bring about interference, advantageously shift nonlinear response curves and create periodic states out of chaos. The phenomenon in which high period fluctuations appear to be generated by low period forcing is examined and different mechanisms compared in a two-strain epidemiological model. The effect of noise as a source of high period fluctuations is also considered. PMID:21397609
Many-body energy localization transition in periodically driven system
D'Alessio, Luca; Polkovnikov, Anatoli
2013-03-01
According to the second law of thermodynamics the total entropy and energy of a system is increased during almost any dynamical process. Notable exceptions are known in noninteracting systems of particles moving in periodic potentials. Here the phenomenon of dynamical localization can prevent heating beyond certain threshold. However, it was believed that driven ergodic systems will always heat without bound. Here, on the contrary, we report strong evidence of dynamical localization transition in periodically driven ergodic systems in the thermodynamic limit. This phenomenon is reminiscent of many-body localization in energy space. We report numerical evidence based on exact diagonalization of small spin chains and theoretical arguments based on the Magnus expansion. Our findings are valid for both classical and quantum systems.
Long period seismic ground motions for isolation systems
International Nuclear Information System (INIS)
In this paper numerical simulations of long period strong ground motions are calculated based on theoretical seismological models of the seismic source and wave propagation. The method includes both near-field and far-field terms and surface waves as well as body waves which allows valid simulations at both short and large distances. Long period ground motions for magnitude 6.75 and magnitude 8.0 events are computed at distances of 3 to 30 km. The resulting response spectral displacements are compared to the SEAOC 1990 spectrum for base-isolated system. At a period of 2 seconds, the SEAOC spectrum is close to the spectrum for a magnitude 8.0 earthquake. However, at a period of 5 seconds, the SEAOC spectrum is much larger than the simulated notions even for a magnitude 8 event
Conditions for high resistance to starvation periods in bioelectrochemical systems.
Ruiz, Yolanda; Ribot-Llobet, Edgar; Baeza, Juan Antonio; Guisasola, Albert
2015-12-01
The present work aims at understanding the performance of bioelectrochemical systems when subjected to different starvation periods, which is very relevant in view of their industrial application or use as biosensor. The results show that both microbial fuel cells (MFC) and microbial electrolysis cells (MEC) could resist starvation periods up to 10-11days without any significant decrease in their performance when endogenous consumption was enabled by closing the circuit in MFC or applying an external voltage in MEC. By contrast, starvation periods longer than 5days in both MFC and MEC when the flow of electrons from the anode to the cathode was not permitted thereby avoiding endogenous consumption, led to a reversible decrease in the cells performance. A longer starvation period of 21-days under open-circuit caused an irreversible performance loss of the MFC. PMID:26163745
Periodic behavior of a nonlinear third order vibrating system
Nakhaie Jazar, Gholamreza; Mahinfalah, Mohammad; Alimi, Mohammad H.; Khazaei, Ali
2005-06-01
A theorem is proved to show that the third order differential equation x?+ f( t, x, x', x?)=0 has nontrivial solutions characterized by x'(0)= x'( ?)=0 when x, x', x? and f( t, x, x', x?) are bounded. A second condition is introduced to prove the existence of periodic solution for this equation. It is shown that the equation has a ?-periodic solution if f( t, x, x', x?) is an even function with respect to x'. The existence and periodicity conditions would be applied to third order systems such as viscoelastic mechanical vibration isolator system. The concepts of Green's function and the Schauder's fixed-point theorem have been used for proving the third-order-existence theorem.
Electrostatics of solvated systems in periodic boundary conditions
Andreussi, Oliviero
2014-01-01
Continuum solvation methods can provide an accurate and inexpensive embedding of quantum simulations in liquid or complex dielectric environments. Notwithstanding a long history and manifold applications to isolated systems in open boundary conditions, their extension to materials simulations --- typically entailing periodic-boundary conditions --- is very recent, and special care is needed to address correctly the electrostatic terms. We discuss here how periodic-boundary corrections developed for systems in vacuum should be modified to take into account solvent effects, using as a general framework the self-consistent continuum solvation model developed within plane-wave density-functional theory [O. Andreussi et al. J. Chem. Phys. 136, 064102 (2012)]. A comprehensive discussion of real-space and reciprocal-space corrective approaches is presented, together with an assessment of their ability to remove electrostatic interactions between periodic replicas. Numerical results for zero-dimensional and two-dimen...
Periodic inspection for safety of CANDU heat transport piping systems
International Nuclear Information System (INIS)
Periodic inspection of heat transport and emergency core cooling piping systems is intended to maintain an adequate level of safety throughout the life of the plant, and to protect plant personnel and the public from the consequences of a failure and release of fission products. This report outlines a rational approach to the periodic inspection based on a fully probabilistic model. It demonstrates the methodology based on theoretical treatment and experimental data whereby the strength of a pressurized pipe or vessel containing a defect could be evaluated. It also shows how the extension of the defect at various lifetimes could be predicted. These relationships are prerequisite for the probabilistic formulation and analysis for the periodic inspection of piping systems
Periodic orbits for an infinite family of classical superintegrable systems
International Nuclear Information System (INIS)
We show that all bounded trajectories in the two-dimensional classical system with the potential V(r,?)=?2r2+(?k2)/(r2cos2k?)+(?k2)/(r2sin2k?) are closed for all integer and rational values of k. The period is T=?/2? and does not depend on k. This agrees with our earlier conjecture suggesting that the quantum version of this system is superintegrable.
Localization of periodic orbits of polynomial systems by ellipsoidal estimates
Energy Technology Data Exchange (ETDEWEB)
Starkov, Konstantin E. [CITEDI-IPN, Avenue del Parque 1310, Mesa de Otay, Tijuana, BC (Mexico)]. E-mail: konst@citedi.mx; Krishchenko, Alexander P. [Bauman Moscow State Technical University, 2nd Baumanskaya Street, 5, Moscow 105005 (Russian Federation)]. E-mail: apkri@999.ru
2005-02-01
In this paper we study the localization problem of periodic orbits of multidimensional continuous-time systems in the global setting. Our results are based on the solution of the conditional extremum problem and using sign-definite quadratic and quartic forms. As examples, the Rikitake system and the Lamb's equations for a three-mode operating cavity in a laser are considered.
Positive periodic solutions of periodic neutral Lotka-Volterra system with distributed delays
Energy Technology Data Exchange (ETDEWEB)
Li Yongkun [Department of Mathematics, Yunnan University Kunming, Yunnan 650091 (China)], E-mail: yklie@ynu.edu.cn
2008-07-15
By using a fixed point theorem of strict-set-contraction, some criteria are established for the existence of positive periodic solutions of the following periodic neutral Lotka-Volterra system with distributed delays (dx{sub i}(t))/(dt) =x{sub i}(t)[a{sub i}(t)-{sigma}{sub j=1}{sup n}b{sub ij}(t){integral}{sub -T{sub ij}}{sup 0}K{sub ij}({theta})x{sub j}( t+{theta})d{theta}-{sigma}{sub j=1}{sup n}c{sub ij}(t){integral}{sub -T{sub ij}}{sup 0}K{sub ij}({theta}) x{sub j}{sup '}(t+{theta})d{theta}],i=1,2,...,n, where a{sub i},b{sub ij},c{sub ij} element of C(R,R{sup +}) (i, j = 1, 2, ..., n) are {omega}-periodic functions, T{sub ij},T{sub ij} element of (0,{infinity}) (i, j = 1, 2, ..., n) and K{sub ij},K{sub ij} element of (R,R{sup +}) satisfying {integral}{sub -T{sub ij}}{sup 0}K{sub ij}({theta})d{theta}=1,{integral}{sub -T{sub ij}}{sup 0}K{sub ij}({theta})d{theta}=1, i, j = 1, 2, ..., n.
Generalized H2 Control Synthesis for Periodic Systems
DEFF Research Database (Denmark)
Wisniewski, Rafal; Stoustrup, Jakob
2001-01-01
A control synthesis of periodic processes is addressed in this paper. A class of linear discrete time periodic systems with performance specified by the generalized $H_2$ operator norm, is considered. The paper proposes an LMI solution to this problem, the sufficient and necessary conditions for solvability of $H_2$ suboptimal control are stated. An algorithm for state feedback control synthesis is provided. The findings are applied for the attitude control of a satellite equipped with electro-magnetic coils, which comprises a very attractive means of attitude corrections for small low-cost spacecraft missions.
Dynamic steady-state of periodically-driven quantum systems
Yudin, V I; Basalaev, M Yu; Kovalenko, D
2015-01-01
Using the density matrix formalism, we prove an existence theorem of the periodic steady-state for an arbitrary periodically-driven system. This state has the same period as the modulated external influence, and it is realized as an asymptotic solution ($t$$\\to$$+\\infty$) due to relaxation processes. The presented derivation simultaneously contains a simple computational algorithm non-using both Floquet and Fourier theories, i.e. our method automatically guarantees a full account of all frequency components. The description is accompanied by the examples demonstrating a simplicity and high efficiency of our method. In particular, for three-level $\\Lambda$-system we calculate the lineshape and field-induced shift of the dark resonance formed by the field with periodically modulated phase. For two-level atom we obtain the analytical expressions for signal of the direct frequency comb spectroscopy with rectangular light pulses. In this case it was shown the radical dependence of the spectroscopy lineshape on pul...
Periodic orbits of hybrid systems and parameter estimation via AD.
Energy Technology Data Exchange (ETDEWEB)
Guckenheimer, John. (Cornell University); Phipps, Eric Todd; Casey, Richard (INRIA Sophia-Antipolis)
2004-07-01
Rhythmic, periodic processes are ubiquitous in biological systems; for example, the heart beat, walking, circadian rhythms and the menstrual cycle. Modeling these processes with high fidelity as periodic orbits of dynamical systems is challenging because: (1) (most) nonlinear differential equations can only be solved numerically; (2) accurate computation requires solving boundary value problems; (3) many problems and solutions are only piecewise smooth; (4) many problems require solving differential-algebraic equations; (5) sensitivity information for parameter dependence of solutions requires solving variational equations; and (6) truncation errors in numerical integration degrade performance of optimization methods for parameter estimation. In addition, mathematical models of biological processes frequently contain many poorly-known parameters, and the problems associated with this impedes the construction of detailed, high-fidelity models. Modelers are often faced with the difficult problem of using simulations of a nonlinear model, with complex dynamics and many parameters, to match experimental data. Improved computational tools for exploring parameter space and fitting models to data are clearly needed. This paper describes techniques for computing periodic orbits in systems of hybrid differential-algebraic equations and parameter estimation methods for fitting these orbits to data. These techniques make extensive use of automatic differentiation to accurately and efficiently evaluate derivatives for time integration, parameter sensitivities, root finding and optimization. The boundary value problem representing a periodic orbit in a hybrid system of differential algebraic equations is discretized via multiple-shooting using a high-degree Taylor series integration method [GM00, Phi03]. Numerical solutions to the shooting equations are then estimated by a Newton process yielding an approximate periodic orbit. A metric is defined for computing the distance between two given periodic orbits which is then minimized using a trust-region minimization algorithm [DS83] to find optimal fits of the model to a reference orbit [Cas04]. There are two different yet related goals that motivate the algorithmic choices listed above. The first is to provide a simple yet powerful framework for studying periodic motions in mechanical systems. Formulating mechanically correct equations of motion for systems of interconnected rigid bodies, while straightforward, is a time-consuming error prone process. Much of this difficulty stems from computing the acceleration of each rigid body in an inertial reference frame. The acceleration is computed most easily in a redundant set of coordinates giving the spatial positions of each body: since the acceleration is just the second derivative of these positions. Rather than providing explicit formulas for these derivatives, automatic differentiation can be employed to compute these quantities efficiently during the course of a simulation. The feasibility of these ideas was investigated by applying these techniques to the problem of locating stable walking motions for a disc-foot passive walking machine [CGMR01, Gar99, McG91]. The second goal for this work was to investigate the application of smooth optimization methods to periodic orbit parameter estimation problems in neural oscillations. Others [BB93, FUS93, VB99] have favored non-continuous optimization methods such as genetic algorithms, stochastic search methods, simulated annealing and brute-force random searches because of their perceived suitability to the landscape of typical objective functions in parameter space, particularly for multi-compartmental neural models. Here we argue that a carefully formulated optimization problem is amenable to Newton-like methods and has a sufficiently smooth landscape in parameter space that these methods can be an efficient and effective alternative. The plan of this paper is as follows. In Section 1 we provide a definition of hybrid systems that is the basis for modeling systems with discontinuities or
Statistics of work distribution in periodically driven closed quantum systems
Dutta, Anirban; Das, Arnab; Sengupta, K.
2015-07-01
We study the statistics of the work distribution P (w ) in a d -dimensional closed quantum system with linear dimension L subjected to a periodic drive with frequency ?0. We show that the corresponding rate function I (w ) =-ln[P (w ) /?0] /Ld after a drive period satisfies a universal lower bound I (0 ) ?nd and has a zero at w =Q Ld/N , where nd and Q are the excitation and the residual energy densities generated during the drive, ?0 is a constant fixed by the normalization of P (w ) , and N is the total number of constituent particles or spins in the system. We supplement our results by calculating I (w ) for a class of d -dimensional integrable models and show that I (w ) has an oscillatory dependence on ?0 originating from Stuckelberg interference generated due to double passage through the critical point or region during the drive. We suggest experiments to test our theory.
Stability Analysis for Multi-Parameter Linear Periodic Systems
DEFF Research Database (Denmark)
Seyranian, A.P.; Solem, Frederik
1999-01-01
This paper is devoted to stability analysis of general linear periodic systems depending on real parameters. The Floquet method and perturbation technique are the basis of the development. We start out with the first and higher-order derivatives of the Floquet matrix with respect to problem parameters. Then the behaviour of simple and multiple multipliers of the system with a change of parameters is studied. Weak and strong interactions of multipliers in the complex plane are treated separately. The presented theory is exemplified and discussed.
Signatures of resonant terrestrial planets in long-period systems
Kennedy, Gareth F
2009-01-01
The majority of extrasolar planets discovered to date have significantly eccentric orbits, some if not all of which may have been produced through planetary migration. During this process, any planets interior to such an orbit would therefore have been susceptible to resonance capture, and hence may exhibit measurable orbital period variations. Here we summarize the results of our investigation into the possibility of detecting low-mass planets which have been captured into the strong 2:1 resonance. Using analytical expressions together with simulated data we showed that it is possible to identify the existence of a low-mass companion in the internal 2:1 resonance by estimating the time-dependant orbital period for piecewise sections of radial velocity data. This works as long as the amplitude of modulation of the orbital period is greater than its uncertainty, which in practice means that the system should not be too close to exact resonance. Here we provide simple expressions for the libration period and th...
Application of Periodic 3DPCM for Core Monitoring System
Energy Technology Data Exchange (ETDEWEB)
Jeong, Wi-Soo; Lee, Hae-Chan; Kim, Hyeong-Seog; Lee, Chang-Kue; Park, Sang-weon [KEPCO NF, Daejeon (Korea, Republic of); Baek, Jin-su [KHNP Hanul Nuclear Power, Uljin (Korea, Republic of)
2014-10-15
The OASIS (Online core Analysis and Simulation System) was developed for WH type PWR which has movable in-core detector. 3DPCM (3D Power Connection Method) was also developed to measure 3D core power distribution using the fixed in-core detector signals and tested for KSNP (Korea Standard Nuclear Plant) such as OPR1000 and APR1400. According to previous study, 3DPCM coupling with neutronics code shows high accuracy. However, this method requires the neutronics code results at each calculation. Therefore, the long calculation time makes it impractical in the online monitoring system requiring the real-time 3D power distribution. In this paper, the 3DPCM based alternative methodology which called periodic 3DPCM is proposed to reduce the calculation time within the reasonable accuracy. The periodic 3DPCM is proposed to reduce the number of neutronics calculation with reasonable accuracy for the application to the online monitoring system development. The periodic 3DPCM is analyzed by 3 cases of sensitivity studies. The errors for the results of power changing operation, ASI changing simulation, and lead control rod insertion are bounded in 0.25%, 1.07%, and 1.15%, respectively. If the update time is shorten as 1 hour, the errors for power changing operation and ASI changing simulation are bounded in 0.07% and 0.56%, respectively. As a result, the update time of 1 hour and prompt update at 30% control rod position change are reasonable considering both conservativeness and effectiveness to update the prediction values. OASIS program utilizing periodic 3DPCM is verified using the plant measurement data and snapshot files which were generated during 45 days operation.
Directory of Open Access Journals (Sweden)
Khazan A.
2011-01-01
Full Text Available In the earlier study (Khazan A. Upper Limit in Mendeleev's Periodic Table - Element No.155. 2nd ed., Svenska fysikarkivet, Stockholm, 2010 the author showed how Rhodium can be applied to the hyperbolic law of the Periodic Table of Elements in order to calculate, with high precision, all other elements conceivable in the Table. Here we obtain the same result, with use of fraction linear functions (adjacent hyperbolas.
ECONOMIC AND FINANCIAL PERIODS INDUCED THROUGH BANKING SYSTEM
Directory of Open Access Journals (Sweden)
Ionita Rodica -Oana
2013-07-01
Full Text Available Abstract:This paper is an empirical study which analyzes the influence of banking system to the economic and financial environment. At the basis of this research there are two subjective definitions of economic instability periods (CII and of financial instability periods (FII and two composite indexes called EWI (Economic Warning Index and FWI (Financial Warning Index defined in a prior research. Because it is not possible to predict the exact point in time at which the crisis sets in, the purpose of this paper is to identify possible vulnerabilities induced through banking system and to treat them in order to mitigate the costs of the economy. I defined a set of eighteen potential leading indicators from banking/financial sector, in the period 2000 - 2012. The countries included in the study are Czech Republic, Hungary and Romania. It was composed a balance panel with seven hundred and eighty observations. There is both a quantitative and qualitative approach. Using econometrics technicques as OLS regressions, Fixed effects and Fixed dummy effects there were identfied significant banking indicators in explaining economic and financial instability periods. Then, I compose a banking index which captures the costs occurred to the banking system and I assess its performance in explaining the economic and financial instability indexes through in the sample and out of the sample techniques. At the basis of my decision to choose a continuous model was the fact that it motivates policy makers in steering policy continuously and the fact that there is no need to decide between yes/ no value of crisis. This research aim to observe the influence of the banking sector evolution to the incidence of economic and financial instability periods and give us a warning regardless any negative trends in the macroeconomic or financial activity, affecting the national or the global situation. Using model simulations on historical data, the model performance was assessed upon in the sample and out of sample estimation techniques. The evaluation results suggest that banking indicators give us a warning signal of the negative trend of economic and financial environment.
Stabilizing non-Hermitian systems by periodic driving
Gong, Jiangbin; Wang, Qing-hai
2015-04-01
The time evolution of a system with a time-dependent non-Hermitian Hamiltonian is in general unstable with exponential growth or decay. A periodic driving field may stabilize the dynamics because the eigenphases of the associated Floquet operator may become all real. This possibility can emerge for a continuous range of system parameters with subtle domain boundaries. It is further shown that the issue of stability of a driven non-Hermitian Rabi model can be mapped onto the band structure problem of a class of lattice Hamiltonians. As a straightforward application, we show how to use the stability of driven non-Hermitian two-level systems (0 dimension in space) to simulate a spectrum analogous to Hofstadter's butterfly that has played a paradigmatic role in quantum Hall physics. The simulation of the band structure of non-Hermitian superlattice potentials with parity-time reversal symmetry is also briefly discussed.
On repellers in quasi-periodically forced logistic map system
Chawanya, Tsuyoshi; Sakai, Takafumi
2014-01-01
We propose a method to identify and to locate "repellers'' in quasi-periodically forced logistic map (QPLM), using a kind of Morse decomposition of nested attracting invariant sets. In order to obtain the invariant sets, we use an auxiliary 1+2-dimensional skew-product map system describing the evolution of a line segment in the phase space of QPLM. With this method, detailed structure of repellers can be visualized, and the emergence of a repeller in QPLM can be detected as...
Stability analysis of periodically switched linear systems using Floquet theory
Directory of Open Access Journals (Sweden)
Gökçek Cevat
2004-01-01
Full Text Available Stability of a switched system that consists of a set of linear time invariant subsystems and a periodic switching rule is investigated. Based on the Floquet theory, necessary and sufficient conditions are given for exponential stability. It is shown that there exists a slow switching rule that achieves exponential stability if at least one of these subsystems is asymptotically stable. It is also shown that there exists a fast switching rule that achieves exponential stability if the average of these subsystems is asymptotically stable. The results are illustrated by examples.
Semiclassical quantization of nonadiabatic systems with hopping periodic orbits
Fujii, Mikiya; Yamashita, Koichi
2015-02-01
We present a semiclassical quantization condition, i.e., quantum-classical correspondence, for steady states of nonadiabatic systems consisting of fast and slow degrees of freedom (DOFs) by extending Gutzwiller's trace formula to a nonadiabatic form. The quantum-classical correspondence indicates that a set of primitive hopping periodic orbits, which are invariant under time evolution in the phase space of the slow DOF, should be quantized. The semiclassical quantization is then applied to a simple nonadiabatic model and accurately reproduces exact quantum energy levels. In addition to the semiclassical quantization condition, we also discuss chaotic dynamics involved in the classical limit of nonadiabatic dynamics.
Coulomb disorder in periodic systems: Effect of unscreened charged impurities
International Nuclear Information System (INIS)
We study the effect of unscreened charged impurities on periodic systems. We show that the long-wavelength component of the disorder becomes long ranged and dominates static correlation functions. On the other hand, because of the statistical tilt symmetry, dynamical properties such as pinning remain unaffected. As a concrete example, we focus on the effect of Coulombian disorder generated by charged impurities on three-dimensional charge density waves with nonlocal elasticity. We calculate the x-ray intensity and find that it is identical to the one produced by thermal fluctuations in a disorder-free smectic-A phase. We discuss the consequences of these results for experiments
(n, 2n) reactions in iodate and periodate systems
International Nuclear Information System (INIS)
The chemical consequences of (n, 2n) reactions on crystalline sodium iodates and sodium periodates, containing sup(127)I or sup(127)I+sup(129)I were investigated measuring the initial yields and the post-irradiation thermal annealing yields at 90 deg C for three separated fractions: Isup(-)+Isup(0), IOsup(3)sup(-) and IOsub(4)sup(-). The results show different effects for each system and neither isotope effect nor qualitative differences on thermal annealing were observed. The influence of the nuclear reaction type, of the hot atom's nature and of the structural and chemical environment are discussed. (author)
Wensing, Thomas
2011-01-01
Firstly, this book provides an introduction into fundamental structural and behavioral aspects of periodic review inventory systems. Secondly, it includes a comprehensive study on analytical and optimization aspects of a specific class of those systems.
Robust detection of periodic time series measured from biological systems
Directory of Open Access Journals (Sweden)
Huttunen Heikki
2005-05-01
Full Text Available Abstract Background Periodic phenomena are widespread in biology. The problem of finding periodicity in biological time series can be viewed as a multiple hypothesis testing of the spectral content of a given time series. The exact noise characteristics are unknown in many bioinformatics applications. Furthermore, the observed time series can exhibit other non-idealities, such as outliers, short length and distortion from the original wave form. Hence, the computational methods should preferably be robust against such anomalies in the data. Results We propose a general-purpose robust testing procedure for finding periodic sequences in multiple time series data. The proposed method is based on a robust spectral estimator which is incorporated into the hypothesis testing framework using a so-called g-statistic together with correction for multiple testing. This results in a robust testing procedure which is insensitive to heavy contamination of outliers, missing-values, short time series, nonlinear distortions, and is completely insensitive to any monotone nonlinear distortions. The performance of the methods is evaluated by performing extensive simulations. In addition, we compare the proposed method with another recent statistical signal detection estimator that uses Fisher's test, based on the Gaussian noise assumption. The results demonstrate that the proposed robust method provides remarkably better robustness properties. Moreover, the performance of the proposed method is preferable also in the standard Gaussian case. We validate the performance of the proposed method on real data on which the method performs very favorably. Conclusion As the time series measured from biological systems are usually short and prone to contain different kinds of non-idealities, we are very optimistic about the multitude of possible applications for our proposed robust statistical periodicity detection method. Availability The presented methods have been implemented in Matlab and in R. Codes are available on request. Supplementary material is available at: http://www.cs.tut.fi/sgn/csb/robustperiodic/.
Optimal stabilization of unstable periodic orbits embedded in chaotic systems
Scientific Electronic Library Online (English)
C.A., Cruz-Villar.
2007-10-01
Full Text Available En este artículo se propone un enfoque basado en el flujo gradiente con el propósito de estabilizar órbitas periódicas inestables inmersas en sistemas caóticos. Tal enfoque considera al problema de estabilización como un problema de control óptimo, lo cual permite obtener una solución en línea al pr [...] oblema de interés, para lo cual se introduce el cálculo de las sensibilidades de los estados con respecto a la entrada de control. El controlador por retroalimentación resultante permite estabilizar órbitas periódicas inestables inmersas en ambas clases de sistemas caoticos, con o sin número de Floquet impar. Además, el enfoque propuesto se extiende para identificar el periodo de la órbita periódica inestable a ser estabilizada, en el caso en que este sea desconocido. Se realizan experimentos de simulación del controlador propuesto, para estabilizar orbitas periódicas inestables de los sistemas de Rössler y de Lorenz. Abstract in english A gradient-flow-based approach is proposed in this paper for stabilizing unstable periodic orbits (UPO) embedded in chaotic systems. In order to obtain an on-line stabilizing solution, the stabilization problem is considered to be an optimal control problem, and system state sensitivities with respe [...] ct to the control input are introduced. The resulting feedback controller is able to stabilize UPO embedded in both kind of systems, with or without an odd Floquet number. Moreover, the proposed approach is easily extended to identifying the period of the UPO to be stabilized when it is unknown. Simulation experiments of the proposed controller are carried out on the Rössler and the Lorenz systems.
Existence and continuation of periodic solutions of autonomous Newtonian systems
Fura, Justyna; Ratajczak, Anna; Rybicki, S?awomir
In this article, we study the existence and the continuation of periodic solutions of autonomous Newtonian systems. To prove the results we apply the infinite-dimensional version of the degree for SO(2)-equivariant gradient operators defined by the third author in Nonlinear Anal. Theory Methods Appl. 23(1) (1994) 83-102 and developed in Topol. Meth. Nonlinear Anal. 9(2) (1997) 383-417. Using the results due to Rabier [Symmetries, Topological degree and a Theorem of Z.Q. Wang, J. Math. 24(3) (1994) 1087-1115] and Wang [Symmetries and calculation of the degree, Chinese Ann. Math. 10 (1989) 520-536] we show that the Leray-Schauder degree is not applicable in the proofs of our theorems, because it vanishes.
A note on discrete-time dynamical systems under periodic perturbation
Directory of Open Access Journals (Sweden)
Xiaosong Yang
2006-07-01
Full Text Available We present some results on the existence and the minimum period of periodic orbits for discrete-time dynamical systems under periodic perturbation. Some examples are presented to illustrate these results.
International Nuclear Information System (INIS)
A period-by-period ion milling system has been developed for final reflection wavefront error correction of an imaging EUV multilayer mirror by a stepwise 0.1 nm-per-period correction of the residual nm figure errors. For effective, gentle and uniform milling of the surface areas selected by a template, the system is designed with a rotating substrate holder exposed to a 150 mm-wide ion beam with a dose homogenizer mask plate. For demonstration of the wavefront correction principle, local milling of a dielectric multilayer mirror for visible light was carried out by the system. The wavefront as measured by a phase shifting interferometer showed that the reflection phase was 'advanced' by the milling, which formed a geometrical depression at the multilayer mirror surface. This confirmed the physical optics principle of our method and proved the procedure of the method being promising and practical for the accurate reflection phase correction of an EUV multilayer mirror.
Directory of Open Access Journals (Sweden)
Dhaou Lassoued
2013-04-01
Full Text Available We prove that a family of $q$-periodic continuous matrix valued function ${A(t}_{tin mathbb{R}}$ has an exponential dichotomy with a projector $P$ if and only if $int_0^t e^{imu s}U(t,sPds$ is bounded uniformly with respect to the parameter $mu$ and the solution of the Cauchy operator Problem $$displaylines{ dot{Y}(t=-Y(tA(t+ e^{i mu t}(I-P ,quad tgeq s cr Y(s=0, }$$ has a limit in $mathcal{L}(mathbb{C}^n$ as s tends to $-infty$ which is bounded uniformly with respect to the parameter $mu$. Here, ${ U(t,s: t, sinmathbb{R}}$ is the evolution family generated by ${A(t}_{tin mathbb{R}}$, $mu$ is a real number and q is a fixed positive number.
Directory of Open Access Journals (Sweden)
Vyatkin V. B.
2013-05-01
Full Text Available In the article, for the first time we have considered group of electrons radial to atomic nucleus with equal value of orbital quantum number and equal sequence of emergence on subshells. As a result of this consideration, the exclusion orbital principle which regulates distribution of electrons in atom on values of spin has been established. On the basis of this principle, the orbital system of distribution of electrons which adequately corresponds to the valid system installed according to the spectral analysis is developed. From positions of orbital system the new explanation of reasons for deviation of the valid system of distribution of electrons in atom from ideal system of consecutive filling of electron shells has been offered and the nature of the empirical rule is opened. The structure of periodic system is also considered and the explanation of the reasons pair repetition of the periods on number of elements is offered. It is thus shown that borders of the chemical periods are displaced relatively borders of the periods of orbital system on two elements to the left
Dynamical System Approach to a Coupled Dispersionless System: Localized and Periodic Traveling Waves
International Nuclear Information System (INIS)
We investigate the dynamical behavior of a coupled dispersionless system describing a current-conducting string with infinite length within a magnetic field. Thus, following a dynamical system approach, we unwrap typical miscellaneous traveling waves including localized and periodic ones. Studying the relative stabilities of such structures through their energy densities, we find that under some boundary conditions, localized waves moving in positive directions are more stable than periodic waves which in contrast stand for the most stable traveling waves in another boundary condition situation. (general)
Gondhalekar, Ravi; Jones, Colin
2009-01-01
State-feedback model predictive control (MPC) of discrete-time linear periodic systems with possibly time-dependent state and control input dimension is considered. States and inputs are subject to hard, mixed, polytopic constraints. It is described how discrete-time linear systems, both time-invariant and periodic, with multirate or multiplexed control inputs can be modeled as such periodic systems. This makes linear periodic systems with possibly time-dependent dimensions a unified, coheren...
Nam, Seung-Il; Woo, Kyung Sik; Ji, Hyo Seon; Stein, Ruediger; Mackensen, Andreas; Matthiessen, Jens
2015-04-01
Authigenic carbonates and mud fractions of the glaciomarine sediments were investigated texturally and geochemically. The sediment core (PS72/410-1) was retrieved using a giant box corer from the central Mendeleev Ridge of the western Arctic Ocean (Station location= Lat. 80°30.37"N, Long. 175°44.38"W) during the Polarstern Arctic expedition (PS72) in 2008. The core is 39 cm long with age of ca. 76 ka BP and was collected from the water depth of 1,802 meters. The sediments show various colours from grey to brown as previously reported in other Arctic deep sea sediments, reflecting glacial-interglacial and/or stadial-interstadial cycles. Authigenic carbonate minerals are present through the whole sequence except for a few centimetres. These authigenic carbonates are composed of high Mg-calcite, low Mg-calcite and aragonite. Various crystal shapes of aragonite and calcite together with clear growth shapes of the crystals suggest that they are inorganic in origin. Highly enriched carbon isotope compositions (?13C = 0 ~ +5‰ vs. PDB) strongly indicate that they formed in methanogenic zone below sediment/water interface by the reaction between anoxic pore fluids and host sediments induced by methanogenic bacteria. However, a wide range of oxygen isotope values (?18O = -5 ~ +5‰ vs. PDB) may indicate that porewater has been changed due to reaction between residual seawater and volcanic sediments. Relatively higher contents of K, Al, Fe and Be values from muddy sediments as well as low ?18O compositions of authigenic carbonates may imply strong input of meltwater from volcanic region (Eastern Arctic region) whereas higher oxygen isotope compositions of authigenic carbonates and higher Sr and K contents of mud sediments may reflect stronger influence from carbonate-rich region (Canadian Arctic region). Mineralogical changes form low to high Mg-calcite together with decrease in Mg, Sr and Fe contents strongly support less freshwater input from glacial mode to interglacial mode. Based on the stable isotope data of authigenic carbonates and trace element contents of mud sediments, formation history of the Upper Deep Polar Water can be reconstructed.
Energy Technology Data Exchange (ETDEWEB)
Tsuru, T; Sakai, Y; Yamamoto, M [Division of Soft X-ray Microscopy, CAMS, IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Tosaka, A, E-mail: tsuru@tagen.tohoku.ac.j [present address: Basic and Applied Science, Division of Science, International College of Arts and Science, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, 236-0027 (Japan)
2009-09-01
A period-by-period ion milling system has been developed for final reflection wavefront error correction of an imaging EUV multilayer mirror by a stepwise 0.1 nm-per-period correction of the residual nm figure errors. For effective, gentle and uniform milling of the surface areas selected by a template, the system is designed with a rotating substrate holder exposed to a 150 mm-wide ion beam with a dose homogenizer mask plate. For demonstration of the wavefront correction principle, local milling of a dielectric multilayer mirror for visible light was carried out by the system. The wavefront as measured by a phase shifting interferometer showed that the reflection phase was 'advanced' by the milling, which formed a geometrical depression at the multilayer mirror surface. This confirmed the physical optics principle of our method and proved the procedure of the method being promising and practical for the accurate reflection phase correction of an EUV multilayer mirror.
Periodic orbits of radially symmetric Keplerian-like systems: A topological degree approach
Fonda, Alessandro; Toader, Rodica
We are concerned with non-autonomous radially symmetric systems with a singularity, which are T-periodic in time. By the use of topological degree theory, we prove the existence of large-amplitude periodic solutions whose minimal period is an integer multiple of T. Precise estimates are then given in the case of Keplerian-like systems, showing some resemblance between the orbits of those solutions and the circular orbits of the corresponding classical autonomous system.
Aeroelastic stability of periodic systems with application to rotor blade flutter
Friedmann, P.; Silverthorn, L. J.
1974-01-01
The dynamics of a helicopter blade in forward flight are described by a system of linear differential equations with periodic coefficients. The stability of this periodic aeroelastic system is determined, using multivariable Floquet-Liapunov theory. The transition matrix at the end of the period is evaluated by: (1) direct numerical integration, and (2) a new, approximate method, which consists in approximating a periodic function by a series of step functions. The numerical accuracy and efficiency of the methods is compared, and the second method is shown to be superior by far. Results illustrating the effect of the periodic coefficients and various blade parameters are presented.
Use of Harmonic Inversion Techniques in the Periodic Orbit Quantization of Integrable Systems
Weibert, K; Wunner, G
2000-01-01
Harmonic inversion has already been proven to be a powerful tool for the analysis of quantum spectra and the periodic orbit orbit quantization of chaotic systems. The harmonic inversion technique circumvents the convergence problems of the periodic orbit sum and the uncertainty principle of the usual Fourier analysis, thus yielding results of high resolution and high precision. Based on the close analogy between periodic orbit trace formulae for regular and chaotic systems the technique is generalized in this paper for the semiclassical quantization of integrable systems. Thus, harmonic inversion is shown to be a universal tool which can be applied to a wide range of physical systems. The method is further generalized in two directions: Firstly, the periodic orbit quantization will be extended to include higher order hbar corrections to the periodic orbit sum. Secondly, the use of cross-correlated periodic orbit sums allows us to significantly reduce the required number of orbits for semiclassical quantizatio...
Confrontation between Quantized Periods of Some Extra-Solar Planetary Systems and Observations
Morcos, A. B.
2013-01-01
A simple formula, using the quantum numbers of solar system planets and some quantized extra-solar planets, to estimate the periods, is done. The quantum numbers, calculated by other authors, have been used to find the orbital periods of solar system planets and some extra-solar planets. Observed periods have been used to compare them with the estimated periods from the given formula. It is found that the given relation is applicable perfectly for the solar system planets. Some extra-solar p...
The cyclicity of period annulus of a quadratic reversible Lotka–Volterra system
International Nuclear Information System (INIS)
We prove that by perturbing the periodic annulus of the quadratic polynomial reversible Lotka–Volterra differential system, inside the class of all quadratic polynomial differential systems we can obtain at most two limit cycles
Controlling chaos in a high dimensional system with periodic parametric perturbations
International Nuclear Information System (INIS)
The effect of applying a periodic perturbation to an accessible parameter of a high-dimensional (coupled-Lorenz) chaotic system is examined. Numerical results indicate that perturbation frequencies near the natural frequencies of the unstable periodic orbits of the chaotic system can result in limit cycles or significantly reduced dimension for relatively small perturbations
The virial theorem and exact properties of density functionals for periodic systems
Mirhosseini, H; Baldsiefen, T; Sanna, A; Proetto, C R; Gross, E K U
2014-01-01
In the framework of density functional theory, scaling and the virial theorem are essential tools for deriving exact properties of density functionals. Preexisting mathematical difficulties in deriving the virial theorem via scaling for periodic systems are resolved via a particular scaling technique. This methodology is employed to derive universal properties of the exchange-correlation energy functional for periodic systems.
Controlling chaos in a high dimensional system with periodic parametric perturbations
Energy Technology Data Exchange (ETDEWEB)
Mirus, K.A.; Sprott, J.C.
1998-10-01
The effect of applying a periodic perturbation to an accessible parameter of a high-dimensional (coupled-Lorenz) chaotic system is examined. Numerical results indicate that perturbation frequencies near the natural frequencies of the unstable periodic orbits of the chaotic system can result in limit cycles or significantly reduced dimension for relatively small perturbations.
Evaluation of electric power distribution systems: period 1984/89
International Nuclear Information System (INIS)
The historical evolution of electric power distribution systems in Brazil, during 1984 to 1989 is described, showing the consumer market with the physical expansion of Distribution Networks and the results of quality from the services made by the companies to their clients. (C.G.C.)
About periodic solutions of a planar system modelling neural activity
Treskov, S.; Volokitin, E.
2001-01-01
We derived explicit symbolic expressions for the first, second, and third Lyapunov coefficients of the complex focus of a planar system modelling activity of a neural network. The analysis of these expressions allowed us to obtain new results about the number and location of limit cycles in the model.
Portable system for periodical verification of area monitors for neutrons
International Nuclear Information System (INIS)
The Neutrons Laboratory develops a project viewing the construction of a portable test system for verification of functioning conditions of neutron area monitors. This device will allow to the users the verification of the calibration maintenance of his instruments at the use installations, avoiding the use of an inadequate equipment related to his answer to the neutron beam response
Implementing Multi-Periodic Critical Systems: from Design to Code Generation
Julien Forget; Frédéric Boniol; David Lesens; Claire Pagetti
2010-01-01
This article presents a complete scheme for the development of Critical Embedded Systems with Multiple Real-Time Constraints. The system is programmed with a language that extends the synchronous approach with high-level real-time primitives. It enables to assemble in a modular and hierarchical manner several locally mono-periodic synchronous systems into a globally multi-periodic synchronous system. It also allows to specify flow latency constraints. A program is translated...
The Kondo effect in periodic narrow-band systems
Irkhin, V Yu
1999-01-01
The Kondo divergences owing to interaction of current carriers with local moments in highly correlated electron systems are considered within the Hubbard and s-d exchange models with infinitely strong on-site interaction. The picture of density of states contaning a peak at the Fermi level is obtained. Various forms of the self-consistent approximation are used. Smearing of the peak owing to spin dynamics and finite temperatures is investigated.
The computerized reactor period measurement system for China fast burst reactor-II
International Nuclear Information System (INIS)
The article simply introduces the hardware, principle, and software of the computerized reactor period measurement system for China Fast Burst Reactor-II (CFBR-II). It also gives the relation between fission yield and pre-reactivity of CFBR-II reactor system of bared reactor with decoupled-component and system of bared reactor with multiple light-material. The computerized measurement system makes the reactor period measurement into automatical and intelligent and also improves the speed and precision of period data on-line process
The orbital periods of three sdB eclipsing binary systems
Kilkenny, D.
2014-12-01
Recent timings of eclipses made between 2011 and 2014 are presented for three binary systems with hot subdwarf primary stars, AA Dor, NY Vir and EC 10246-2707. In the case of AA Dor, the period remains constant. In NY Vir, a rapidly pulsating sdBVr with a cool companion, the period change now appears more complex than can be described by a simple quadratic. EC 10246-2707, which has previously appeared to have a constant period, now appears to be showing a significant period increase. The effect of gravitational radiation in HW Vir-like systems is briefly discussed.
Low energy theories describing topological properties of periodic systems
Budich, Jan Carl
2011-01-01
We discuss the ostensible paradox between the abstract definition of physical observables as topological properties of the Brillouin zone (BZ) of a condensed matter system as a whole and their successful prediction by effective low energy theories the validity of which is limited to the closest vicinity of a high symmetry point in the BZ. We show that the control parameter of a topological phase transition can act as the deformation parameter of a homotopy transformation localizing the topological defect in an arbitrarily small neighbourhood of a single point in $k$-space. We illustrate this mechanism and its limitations with the help of experimentally relevant examples such as HgTe/CdTe quantum wells and bilayer graphene nanostructures.
Controlling chaos in low and high dimensional systems with periodic parametric perturbations
International Nuclear Information System (INIS)
The effect of applying a periodic perturbation to an accessible parameter of various chaotic systems is examined. Numerical results indicate that perturbation frequencies near the natural frequencies of the unstable periodic orbits of the chaotic systems can result in limit cycles for relatively small perturbations. Such perturbations can also control or significantly reduce the dimension of high-dimensional systems. Initial application to the control of fluctuations in a prototypical magnetic fusion plasma device will be reviewed
Controlling chaos in low and high dimensional systems with periodic parametric perturbations
Energy Technology Data Exchange (ETDEWEB)
Mirus, K.A.; Sprott, J.C.
1998-06-01
The effect of applying a periodic perturbation to an accessible parameter of various chaotic systems is examined. Numerical results indicate that perturbation frequencies near the natural frequencies of the unstable periodic orbits of the chaotic systems can result in limit cycles for relatively small perturbations. Such perturbations can also control or significantly reduce the dimension of high-dimensional systems. Initial application to the control of fluctuations in a prototypical magnetic fusion plasma device will be reviewed.
Stabilization of Periodic Solutions in a Thedered Satellite System by Damping Injection
DEFF Research Database (Denmark)
Larsen, Martin Birkelund; Blanke, Mogens
2009-01-01
A spacecraft with electrodynamic tether orbiting the Earth will be subject to a periodic forcing term induced by the variation of the magnetic field along the orbit. The periodic forcing term leads to a family of unstable periodic solutions for a tether carrying a constant current. This paper presents a control design for stabilizing these periodic solutions. The design consists of a control law for stabilising the open-loo equibrilibrium and a bias term which forces the system trajectory away from the equilibrium. The tether needs to be positioned away from open-loop equilibrium for the tether to affect the orbit parameters. An approximation of the periodic solutions of the closed loop system is found as a series expansion in the parameter plane spanned by the controller gain and the bias term. The stability of the solutions is investigated using linear Floquet analysis of the variational equation and the region of stable periodic solutions in the parameter plane is found.
A numerical method for computing time-periodic solutions in dissipative wave systems
Yang, Jianke
2014-01-01
A numerical method is proposed for computing time-periodic and relative time-periodic solutions in dissipative wave systems. In such solutions, the temporal period, and possibly other additional internal parameters such as the propagation constant, are unknown priori and need to be determined along with the solution itself. The main idea of the method is to first express those unknown parameters in terms of the solution through quasi-Rayleigh quotients, so that the resulting...
Long-time behavior of periodically driven isolated interacting lattice systems
D'Alessio, Luca; Rigol, Marcos
2014-01-01
We study the dynamics of isolated interacting spin chains that are periodically driven by sudden quenches. Using full exact diagonalization of finite chains, we show that these systems exhibit three distinct regimes. For short driving periods, the Floquet Hamiltonian is well approximated by the time-averaged Hamiltonian, while for long periods the evolution operator exhibits properties of random matrices of a Circular Ensemble (CE). In-between, there is a crossover regime. B...
Gradient Based Control and Synchronization of Lorenz System with Periodic Parametric Forcing
Directory of Open Access Journals (Sweden)
Mohammad Ali Khan
2012-08-01
Full Text Available Several important properties of chaos synchronization with gradientbased control of chaotic system with periodic parametric forcing remainstill unexplored. This paper investigates the behavior of the Lorenz systemto change from chaotic to periodic, parametric forcing also entrainsthe system output with the forcing frequency. Secondly synchronizationof two identically chaotic Lorenz systems are derived by linear feedbackcontrol and then discussed the gradient based control method for Lorenzsystem with periodic parametric forcing. Finally numerical simulationresults are presented to show the feasibility and effectiveness of the approach.
Stochastic Long Term Modelling of a Drainage System with Estimation of Return Period Uncertainty
DEFF Research Database (Denmark)
Thorndahl, SØren
2008-01-01
Long term prediction of maximum water levels and combined sewer overflow (CSO) in drainage systems are associated with large uncertainties. Especially on rainfall inputs, parameters, and assessment of return periods. This paper proposes a Monte Carlo based methodology for stochastic prediction of both maximum water levels as well as CSO volumes based on operations of the urban drainage model MOUSE (Lindberg and Joergensen 1986) in a single catchment case study. Results show quite a wide confidence interval of the model predictions especially on the large return periods. Traditionally, return periods of drainage system predictions are based on ranking, but this paper proposes a new methodology for the assessment of return periods. Based on statistics of characteristic rainfall parameters and correlation with drainage system predictions, it is possible to predict return periods more reliably, and with smaller confidence bands compared to the traditional methodology.
Stochastic long term modelling of a drainage system with estimation of return period uncertainty
DEFF Research Database (Denmark)
Thorndahl, SØren
2009-01-01
Long term prediction of maximum water levels and combined sewer overflow (CSO) in drainage systems are associated with large uncertainties. Especially on rainfall inputs, parameters, and assessment of return periods. This paper proposes a Monte Carlo based methodology for stochastic prediction of both maximum water levels as well as CSO volumes based on operations of the urban drainage model MOUSE (Lindberg and Joergensen 1986) in a single catchment case study. Results show quite a wide confidence interval of the model predictions especially on the large return periods. Traditionally, return periods of drainage system predictions are based on ranking, but this paper proposes a new methodology for the assessment of return periods. Based on statistics of characteristic rainfall parameters and correlation with drainage system predictions, it is possible to predict return periods more reliably, and with smaller confidence bands compared to the traditional methodology.
Dynamic behaviors of the periodic Lotka-Volterra competing system with impulsive perturbations
International Nuclear Information System (INIS)
In this paper, we investigate a classical periodic Lotka-Volterra competing system with impulsive perturbations. The conditions for the linear stability of trivial periodic solution and semi-trivial periodic solutions are given by applying Floquet theory of linear periodic impulsive equation, and we also give the conditions for the global stability of these solutions as a consequence of some abstract monotone iterative schemes introduced in this paper, which will be also used to get some sufficient conditions for persistence. By using the method of coincidence degree, the conditions for the existence of at least one strictly positive (componentwise) periodic solution are derived. The theoretical results are confirmed by a specific example and numerical simulations. It shows that the dynamic behaviors of the system we consider are quite different from the corresponding system without pulses
Dynamic behaviors of the periodic Lotka-Volterra competing system with impulsive perturbations
Energy Technology Data Exchange (ETDEWEB)
Liu Bing [Department of Mathematics, Anshan Normal University, Anshan 114005, Liaoning (China) and Department of Mathematics, Xinjiang University, Urumqi 830046, Xinjiang (China)]. E-mail: liubing529@126.com; Teng Zhidong [Department of Mathematics, Xinjiang University, Urumqi 830046, Xinjiang (China); Liu Wanbo [Senior Middle School of Anshan Steel-Iron Company, Anshan 114034, Liaoning (China)
2007-01-15
In this paper, we investigate a classical periodic Lotka-Volterra competing system with impulsive perturbations. The conditions for the linear stability of trivial periodic solution and semi-trivial periodic solutions are given by applying Floquet theory of linear periodic impulsive equation, and we also give the conditions for the global stability of these solutions as a consequence of some abstract monotone iterative schemes introduced in this paper, which will be also used to get some sufficient conditions for persistence. By using the method of coincidence degree, the conditions for the existence of at least one strictly positive (componentwise) periodic solution are derived. The theoretical results are confirmed by a specific example and numerical simulations. It shows that the dynamic behaviors of the system we consider are quite different from the corresponding system without pulses.
Self-similarities of periodic structures for a discrete model of a two-gene system
Energy Technology Data Exchange (ETDEWEB)
Souza, S.L.T. de, E-mail: thomaz@ufsj.edu.br [Departamento de Física e Matemática, Universidade Federal de São João del-Rei, Ouro Branco, MG (Brazil); Lima, A.A. [Escola de Farmácia, Universidade Federal de Ouro Preto, Ouro Preto, MG (Brazil); Caldas, I.L. [Instituto de Física, Universidade de São Paulo, São Paulo, SP (Brazil); Medrano-T, R.O. [Departamento de Ciências Exatas e da Terra, Universidade Federal de São Paulo, Diadema, SP (Brazil); Guimarães-Filho, Z.O. [Aix-Marseille Univ., CNRS PIIM UMR6633, International Institute for Fusion Science, Marseille (France)
2012-03-12
We report self-similar properties of periodic structures remarkably organized in the two-parameter space for a two-gene system, described by two-dimensional symmetric map. The map consists of difference equations derived from the chemical reactions for gene expression and regulation. We characterize the system by using Lyapunov exponents and isoperiodic diagrams identifying periodic windows, denominated Arnold tongues and shrimp-shaped structures. Period-adding sequences are observed for both periodic windows. We also identify Fibonacci-type series and Golden ratio for Arnold tongues, and period multiple-of-three windows for shrimps. -- Highlights: ? The existence of noticeable periodic windows has been reported recently for several nonlinear systems. ? The periodic window distributions appear highly organized in two-parameter space. ? We characterize self-similar properties of Arnold tongues and shrimps for a two-gene model. ? We determine the period of the Arnold tongues recognizing a Fibonacci-type sequence. ? We explore self-similar features of the shrimps identifying multiple period-three structures.
HirofumiMorishita
2013-01-01
Early temporary windows of heightened brain plasticity called critical periods developmentally sculpt neural circuits and contribute to adult behavior. Regulatory mechanisms of visual cortex development –the preeminent model of experience-dependent critical period plasticity- actively limit adult plasticity and have proved fruitful therapeutic targets to reopen plasticity and rewire faulty visual system connections later in life. Interestingly, these molecular mechanisms have been implicated ...
Existence of Periodic Solutions of Linear Hamiltonian Systems with Sublinear Perturbation
Zhiqing Han
2010-01-01
We investigate the existence of periodic solutions of linear Hamiltonian systems with a nonlinear perturbation. Under generalized Ahmad-Lazer-Paul type coercive conditions for the nonlinearity on the kernel of the linear part, existence of periodic solutions is obtained by saddle point theorems. A note on a result of Rabinowitz is also given.
Scattering problem for quantum system with time-dependent periodic Hamiltonian
International Nuclear Information System (INIS)
Scattering theory for quantum systems located in time-dependent periodic strong field is considered. Scattering matrix is constructed in the quasi-energy states basis. Transition operators are introduced, perturbation series is constructed, interstates transition rate is calculated. Optical theorem is generalized in case of periodic field. (author). 7 refs
Hopf-pitchfork bifurcation and periodic phenomena in nonlinear financial system with delay
International Nuclear Information System (INIS)
Highlights: ? We derive the unfolding of a financial system with Hopf-pitchfork bifurcation. ? We show the coexistence of a pair of stable small amplitudes periodic solutions. ? At the same time, also there is a pair of stable large amplitudes periodic solutions. ? Chaos can appear by period-doubling bifurcation far away from Hopf-pitchfork value. ? The study will be useful for interpreting economics phenomena in theory. - Abstract: In this paper, we identify the critical point for a Hopf-pitchfork bifurcation in a nonlinear financial system with delay, and derive the normal form up to third order with their unfolding in original system parameters near the bifurcation point by normal form method and center manifold theory. Furthermore, we analyze its local dynamical behaviors, and show the coexistence of a pair of stable periodic solutions. We also show that there coexist a pair of stable small-amplitude periodic solutions and a pair of stable large-amplitude periodic solutions for different initial values. Finally, we give the bifurcation diagram with numerical illustration, showing that the pair of stable small-amplitude periodic solutions can also exist in a large region of unfolding parameters, and the financial system with delay can exhibit chaos via period-doubling bifurcations as the unfolding parameter values are far away from the critical point of the Hopf-pitchfork bifurcation.
Liu, Xinxin; Iwakiri, Kazuyuki; Sotoyama, Midori; Iwanaga, Koichi
2013-01-01
The purpose of the present study was to examine how an inserted break influences the cardiovascular and central nervous system responses during periods of mental work. Twelve males conducted two 20-min periods of mental work with a 3-min break between them. Cardiovascular and central nervous system responses were measured continuously. In comparison to the baseline, cardiovascular responses increased continuously even after the inserted break, while, on the contrary, central nervous system activity did not significantly increase during the work periods but relaxed during the break. The work performance increased during the second work period. These results suggest that the inserted break proposed by VDT guidelines in Japan was effective in relaxing the central nervous system but was insufficient to prevent the increase in cardiovascular load. The results also imply that taking rests frequently is important not only to maintaining performance but also to preventing cumulative physiological workloads. PMID:23268833
International Nuclear Information System (INIS)
In this thesis, the possibility of controlling low- and high-dimensional chaotic systems by periodically driving an accessible system parameter is examined. This method has been carried out on several numerical systems and the MST Reversed Field Pinch. The numerical systems investigated include the logistic equation, the Lorenz equations, the Roessler equations, a coupled lattice of logistic equations, a coupled lattice of Lorenz equations, the Yoshida equations, which model tearing mode fluctuations in a plasma, and a neural net model for magnetic fluctuations on MST. This method was tested on the MST by sinusoidally driving a magnetic flux through the toroidal gap of the device. Numerically, periodic drives were found to be most effective at producing limit cycle behavior or significantly reducing the dimension of the system when the perturbation frequency was near natural frequencies of unstable periodic orbits embedded in the attractor of the unperturbed system. Several different unstable periodic orbits have been stabilized in this way for the low-dimensional numerical systems, sometimes with perturbation amplitudes that were less than 5% of the nominal value of the parameter being perturbed. In high-dimensional systems, limit cycle behavior and significant decreases in the system dimension were also achieved using perturbations with frequencies near the natural unstable periodic orbit frequencies. Results for the MST were not this encouraging, most likely because of an insufficient drive amplitude, the extremely high dimension of the plasma behavior, large amounts of noise, and a lack of stationarity in the transient plasma pulses
Energy Technology Data Exchange (ETDEWEB)
Mirus, K.A.
1998-06-01
In this thesis, the possibility of controlling low- and high-dimensional chaotic systems by periodically driving an accessible system parameter is examined. This method has been carried out on several numerical systems and the MST Reversed Field Pinch. The numerical systems investigated include the logistic equation, the Lorenz equations, the Roessler equations, a coupled lattice of logistic equations, a coupled lattice of Lorenz equations, the Yoshida equations, which model tearing mode fluctuations in a plasma, and a neural net model for magnetic fluctuations on MST. This method was tested on the MST by sinusoidally driving a magnetic flux through the toroidal gap of the device. Numerically, periodic drives were found to be most effective at producing limit cycle behavior or significantly reducing the dimension of the system when the perturbation frequency was near natural frequencies of unstable periodic orbits embedded in the attractor of the unperturbed system. Several different unstable periodic orbits have been stabilized in this way for the low-dimensional numerical systems, sometimes with perturbation amplitudes that were less than 5% of the nominal value of the parameter being perturbed. In high-dimensional systems, limit cycle behavior and significant decreases in the system dimension were also achieved using perturbations with frequencies near the natural unstable periodic orbit frequencies. Results for the MST were not this encouraging, most likely because of an insufficient drive amplitude, the extremely high dimension of the plasma behavior, large amounts of noise, and a lack of stationarity in the transient plasma pulses.
Research on anti-disturbance property of HFETRC period monitoring system
International Nuclear Information System (INIS)
The anti-disturbance problem of the period monitoring system for test reactor critical assembly is mainly discussed and how to judge and search for the interference source using spotting experimental methods starting from the practical engineering without special equipment is introduced. So the electro-magnetic interference is removed. After finding out the reason, four measures are adopted to build up the anti-disturbance ability of the period monitoring system. (authors)
A general method for the existence of periodic solutions of differential systems in the plane
Fonda, Alessandro; Sfecci, Andrea
We propose a general method to prove the existence of periodic solutions for planar systems of ordinary differential equations, which can be used in many different circumstances. Applications are given to some nonresonant cases, even for systems with superlinear growth in some direction, or with a singularity. Systems "at resonance" are also considered, provided a Landesman-Lazer type of condition is assumed.
Relative equailibria and relative periodic solutions in systems with time-delay and $S^{1}$ symmetry
Yanchuk, Serhiy
2013-01-01
We study properties of basic solutions in systems with dime delays and $S^1$-symmetry. Such basic solutions are relative equilibria (CW solutions) and relative periodic solutions (MW solutions). It follows from the previous theory that the number of CW solutions grows generically linearly with time delay $\\tau$. Here we show, in particular, that the number of relative periodic solutions grows generically as $\\tau^2$ when delay increases. Thus, in such systems, the relative periodic solutions are more abundant than relative equilibria. The results are directly applicable to, e.g., Lang-Kobayashi model for the lasers with delayed feedback. We also study stability properties of the solutions for large delays.
The period-ratio and mass-ratio correlation in extra-solar multiple planetary systems
Jiang, Ing-Guey; Yeh, Li-Chin; Hung, Wen-Liang
2015-04-01
Employing the data from orbital periods and masses of extra-solar planets in 166 multiple planetary systems, the period ratio and mass ratio of adjacent planet pairs are studied. The correlation between the period ratio and mass ratio is confirmed, with a correlation coefficient of 0.5303 with a 99 per cent confidence interval (0.3807, 0.6528). A comparison with the distribution of synthetic samples from a Monte Carlo simulation reveals the imprint of planet-planet interactions on the formation of adjacent planet pairs in multiple planetary systems.
The Period-Ratio and Mass-Ratio Correlation in Extra-Solar Multiple Planetary Systems
Jiang, Ing-Guey; Hung, Wen-Liang
2015-01-01
Employing the data from orbital periods and masses of extra-solar planets in 166 multiple planetary systems, the period-ratio and mass-ratio of adjacent planet pairs are studied. The correlation between the period-ratio and mass-ratio is confirmed and found to have a correlation coefficient of 0.5303 with a 99% confidence interval (0.3807, 0.6528). A comparison with the distribution of synthetic samples from a Monte Carlo simulation reveals the imprint of planet-planet interactions on the formation of adjacent planet pairs in multiple planetary systems.
Localization of periodic orbits of the Roessler system under variation of its parameters
International Nuclear Information System (INIS)
The localization problem of compact invariant sets of the Roessler system is considered in this paper. The main interest is attracted to a localization of periodic orbits. We establish a number of algebraic conditions imposed on parameters under which the Roessler system has no compact invariant sets contained in half-spaces z > 0; z < 0 and in some others. We prove that if parameters (a, b, c) of the Roessler system are such that this system has no equilibrium points then it has no periodic orbits as well. In addition, we give localization conditions of compact invariant sets by using linear functions and one quadratic function
Localization of periodic orbits of the Roessler system under variation of its parameters
Energy Technology Data Exchange (ETDEWEB)
Starkov, Konstantin E. [CITEDI-IPN, Av. del Parque 1310, Mesa de Otay, Tijuana, BC (Mexico)]. E-mail: konst@citedi.mx; Starkov, Konstantin K. [UABC - Campus Tijuana, Facultad de Ciencias Quimicas e Ingenieria, Calzada Tecnologico, Mesa de Otay, Tijuana, BC (Mexico)
2007-08-15
The localization problem of compact invariant sets of the Roessler system is considered in this paper. The main interest is attracted to a localization of periodic orbits. We establish a number of algebraic conditions imposed on parameters under which the Roessler system has no compact invariant sets contained in half-spaces z > 0; z < 0 and in some others. We prove that if parameters (a, b, c) of the Roessler system are such that this system has no equilibrium points then it has no periodic orbits as well. In addition, we give localization conditions of compact invariant sets by using linear functions and one quadratic function.
Periodic solutions for a two-species nonautonomous competition system with diffusion and impulses
Energy Technology Data Exchange (ETDEWEB)
Dong Lingzhen [Department of Mathematics, Taiyuan University of Technology, Taiyuan 030024 (China)]. E-mail: linzhen_dong@yahoo.com.cn; Chen Lansun [Department of Applied Mathematics, Dalian University of Technology, Dalian 116023 (China); Shi Peilin [Department of Mathematics, Taiyuan University of Technology, Taiyuan 030024 (China)
2007-06-15
By re-estimating the upper bound of {integral}{sub 0}{sup {omega}}e{sup u{sub i}}{sup (t)}dt (i=1,2), we generalize a result about the existence of a positive periodic solution for a two-species nonautonomous patchy competition system with time delay. Based on that system, we consider the impulsive harvesting and stocking, and establish a two-species nonautonomous competition Lotka-Volterra system with diffusion and impulsive effects. With the continuation theorem of coincidence degree theory, we obtain the existence of a positive periodic solution for such a system. At last, two examples are given to demonstrate our results.
Periodic solutions for a two-species nonautonomous competition system with diffusion and impulses
International Nuclear Information System (INIS)
By re-estimating the upper bound of ?0?eui(t)dt (i=1,2), we generalize a result about the existence of a positive periodic solution for a two-species nonautonomous patchy competition system with time delay. Based on that system, we consider the impulsive harvesting and stocking, and establish a two-species nonautonomous competition Lotka-Volterra system with diffusion and impulsive effects. With the continuation theorem of coincidence degree theory, we obtain the existence of a positive periodic solution for such a system. At last, two examples are given to demonstrate our results
Periodic orbits and their stability in the Rössler prototype-4 system
International Nuclear Information System (INIS)
For the Rössler prototype-4 system x.=?y?z, y.=x, z.=?y(1?y)??z we prove the existence of periodic orbits and study their stability or instability. The main tool for proving these results is the averaging theory. Recently the existence of some of these periodic orbits were detected numerically. -- Highlights: ? We deal with the Rössler prototype-4 system x.=?y?z, y.=x, z.=?y(1?y)??z. ? It is one of the simplest autonomous differential equations exhibiting chaos. ? Recently some periodic orbits for this system has been detected numerically. ? We provide an analytical proof of these orbits and study their stability. ? Also we prove the existence of periodic orbits not detected numerically.
Ultra-Short-Period Binary Systems in the OGLE Fields Toward the Galactic Bulge
Soszynski, I; Pilecki, B; Mroz, P; Udalski, A; Szymanski, M K; Pietrzynski, G; Wyrzykowski, L; Ulaczyk, K; Poleski, R; Kozlowski, S; Pietrukowicz, P; Skowron, J; Pawlak, M
2015-01-01
We present a sample of 242 ultra-short-period (P < 0.22 d) eclipsing and ellipsoidal binary stars identified in the OGLE fields toward the Galactic bulge. Based on the light curve morphology, we divide the sample into candidates for contact binaries and non-contact binaries. In the latter group we distinguish binary systems consisting of a cool main-sequence star and a B-type subdwarf (HW Vir stars) and candidates for cataclysmic variables, including five eclipsing dwarf novae. One of the detected eclipsing binary systems - OGLE-BLG-ECL-000066 - with the orbital period below 0.1 d, likely consists of M dwarfs in a nearly contact configuration. If confirmed, this would be the shortest-period M-dwarf binary system currently known. We discuss possible evolutionary mechanisms that could lead to the orbital period below 0.1 d in an M-dwarf binary.
Shang, Haibin; Wu, Xiaoyu; Cui, Pingyuan
2015-01-01
This paper investigates the periodic motion of a particle in the doubly synchronous binary asteroid systems. Two typical doubly synchronous systems, 809 Lundia and 3169 Ostro, are discussed in detail. Under the Roche figure assumption, the two bodies of doubly synchronous system can be modeled as two triaxial ellipsoids. The Ivory's theorem is used to derive the gravitational potential of the system. Then, a global numerical method, which combines grid searching and differential correction, is developed for systematically searching periodic orbits in the doubly synchronous systems. A total of 30 and 28 families of periodic orbits around Lundia and Ostro are found, respectively. Furthermore, on the basis of the analysis of morphology, stabilities and invariant manifolds, the potential applications of these periodic orbit families are studied. Several quasi-circular orbit families with low instability index are found to be suitable for the observation of the two typical binary systems. The invariant manifolds of some periodic orbits near the equilibrium points can provide the fuel-free trajectories to achieve the ballistic landing to the surface of the asteroids and transfer between the binary asteroids.
H2 OPTIMAL CONTROLLERS FOR A LARGE CLASS OF LINEAR STOCHASTIC SYSTEMS WITH PERIODIC COEFFICIENTS
Directory of Open Access Journals (Sweden)
Adrian-Mihail Stoica
2011-07-01
Full Text Available In this paper the H2 type optimization problem for a class of timevarying linear stochastic systems modeled by Ito differential equations and Markovian jumping with periodic coefficients is considered. The main goal of such an optimization problem is to minimize the effect of additive white noise perturbations on a suitable output of the controlled system. It is assumed that only an output is available for measurements.The solution of the considered optimization problem is constructed via the stabilizing solutions of some suitable systems of generalized Riccati differential equations with periodic coefficients.
Implementing Multi-Periodic Critical Systems: from Design to Code Generation
Directory of Open Access Journals (Sweden)
Julien Forget
2010-03-01
Full Text Available This article presents a complete scheme for the development of Critical Embedded Systems with Multiple Real-Time Constraints. The system is programmed with a language that extends the synchronous approach with high-level real-time primitives. It enables to assemble in a modular and hierarchical manner several locally mono-periodic synchronous systems into a globally multi-periodic synchronous system. It also allows to specify flow latency constraints. A program is translated into a set of real-time tasks. The generated code (C code can be executed on a simple real-time platform with a dynamic-priority scheduler (EDF. The compilation process (each algorithm of the process, not the compiler itself is formally proved correct, meaning that the generated code respects the real-time semantics of the original program (respect of periods, deadlines, release dates and precedences as well as its functional semantics (respect of variable consumption.
Implementing Multi-Periodic Critical Systems: from Design to Code Generation
Forget, Julien; Lesens, David; Pagetti, Claire
2010-01-01
This article presents a complete scheme for the development of Critical Embedded Systems with Multiple Real-Time Constraints. The system is programmed with a language that extends the synchronous approach with high-level real-time primitives. It enables to assemble in a modular and hierarchical manner several locally mono-periodic synchronous systems into a globally multi-periodic synchronous system. It also allows to specify flow latency constraints. A program is translated into a set of real-time tasks. The generated code (\\C\\ code) can be executed on a simple real-time platform with a dynamic-priority scheduler (EDF). The compilation process (each algorithm of the process, not the compiler itself) is formally proved correct, meaning that the generated code respects the real-time semantics of the original program (respect of periods, deadlines, release dates and precedences) as well as its functional semantics (respect of variable consumption).
Existence of positive periodic solution of mutualism system with several delays
Energy Technology Data Exchange (ETDEWEB)
Wu Haihui [College of Mathematics and Computer Science, Fuzhou University, Fuzhou 350002 (China); Department of Computer Science and Technology, Sunshine College, Fuzhou University, Fuzhou 350002 (China); Xia Yonghui [College of Mathematics and Computer Science, Fuzhou University, Fuzhou 350002 (China)], E-mail: yhxia@fzu.edu.cn; Lin Muren [College of Mathematics and Computer Science, Fuzhou University, Fuzhou 350002 (China)
2008-04-15
In this paper, by using Mawhin coincidence degree, some sufficient conditions are obtained for the global existence of positive periodic solutions of a mutualism systems with bounded and unbounded delays. Our results generalize significantly improve those of Gopalsamy and He [Gopalsamy K, He XZ. Persistence, attractivity, and delay in facultative mutualism. J Math Anal Appl 1997;215:154-73], Yang et al. [Yang F, Jiang D, Ying A. Existence of positive solution of multidelays facultative mutualism system. J Eng Math 2002;3:64-8], Chen et al. [Chen FD, Shi JL, Chen XX. Periodicity in Lotka-Volterra facultative mutualism system with several delays. J Eng Math 2004;21(3)] and Xia and Lin [Xia YH, Lin M, Existence of positive periodic solution of mutualism system with infinite delays. Ann Diff Eqs 2005;21(3):448-53].
Directory of Open Access Journals (Sweden)
Xuan Li
2009-01-01
Full Text Available This study investigates the problem of integrity against actuator failures for networked control systems under variable-period sampling. Assuming that the distance between any two consecutive sampling instants is less than a given bound, by using the input delay approach, the networked control systems under variable-period sampling are transformed into the continuous-time networked control systems under time-varying delays. Then the existence conditions of guaranteed cost fault-tolerant control law is testified in terms of the Lyapunov stability theory combined with Linear Matrix Inequalities (LMIs. Furthermore, the guaranteed cost fault-tolerant controller gain and the minimization guaranteed cost can be obtained by solving a minimization problem. A numerical simulation example demonstrates the conclusions are feasible and effective. The proposed control method resolves the problems of variable-period sampling and actuator failures, which meets the requirements in industrial networked control systems.
Positive Periodic Solution for a Two-Species Predator-Prey System
Meiyu Cao; Xiaoping Li; Xiangjun Dai
2014-01-01
A two-species predator-prey system with time delay in a two-patch environment is investigated. By using a continuation theorem based on coincidence degree theory, we obtain some sufficient conditions for the existence of periodic solution for the system.
Periodic solutions for a delayed predator-prey system with dispersal and impulses
Directory of Open Access Journals (Sweden)
Shijie Dong
2005-03-01
Full Text Available A delayed predator-prey system with prey dispersal in n-patch environments and impulse effects is investigated. By using Gaines and Mawhin's continuation theorem of coincidence degree theory, a set of easily verifiable sufficient conditions are derived for the existence of positive periodic solutions to the system.
Global attractivity of almost periodic solutions for competitive Lotka-Volterra diffusion system
Muhammadhaji, Ahmadjan; Teng, Zhidong; Rehim, Mehbuba
2013-01-01
In this paper, two competitive Lotka-Volterra populations in the two-patch-system with diffusion are considered. Each of the two spiecies can diffuse indepently and discretely between its in intrapatch and interpatch. By means of constructing Liapunov function, under moderate condition, the system has a unique almost periodic solution and which is asymptotically stable and globally attractive .
Energy Technology Data Exchange (ETDEWEB)
Zhao Hongyong [Department of Mathematics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)]. E-mail: hongyongz@126.com; Ding Nan [Department of Mathematics, Xinjiang Normal University, Urumqi 830054 (China)
2006-07-15
In this paper, Lotka-Volterra competition-predator system with variable delays is considered. Some sufficient conditions ensuring the existence and global attractivity of periodic solution for this system are obtained by using coincidence degree theory and Lyapunov functional method. An example is also worked out to demonstrate the advantages of our results.
Stabilizing periodic orbits of chaotic systems using fuzzy adaptive sliding mode control
International Nuclear Information System (INIS)
In this paper by using a combination of fuzzy identification and the sliding mode control a fuzzy adaptive sliding mode scheme is designed to stabilize the unstable periodic orbits of chaotic systems. The chaotic system is assumed to have an affine form x(n) = f(X) + g(X)u where f and g are unknown functions. Using only the input-output data obtained from the underlying dynamical system, two fuzzy systems are constructed for identification of f and g. Two distinct methods are utilized for fuzzy modeling, the least squares and the gradient descent techniques. Based on the estimated fuzzy models, an adaptive controller, which works through the sliding mode control, is designed to make the system track the desired unstable periodic orbits. The stability analysis of the overall closed loop system is presented in the paper and the effectiveness of the proposed adaptive scheme is numerically investigated. As a case of study, modified Duffing system is selected for applying the proposed method to stabilize its 2? and 4? periodic orbits. Simulation results show the high performance of the method for stabilizing the unstable periodic orbits of unknown chaotic systems
International Nuclear Information System (INIS)
In this paper, Lotka-Volterra competition-predator system with variable delays is considered. Some sufficient conditions ensuring the existence and global attractivity of periodic solution for this system are obtained by using coincidence degree theory and Lyapunov functional method. An example is also worked out to demonstrate the advantages of our results
Laplace transformations of hydrodynamic type systems in Riemann invariants periodic sequences
Ferapontov, E V
1997-01-01
The conserved densities of hydrodynamic type system in Riemann invariants satisfy a system of linear second order partial differential equations. For linear systems of this type Darboux introduced Laplace transformations, generalising the classical transformations in the scalar case. It is demonstrated that Laplace transformations can be pulled back to the transformations of the corresponding hydrodynamic type systems. We discuss periodic Laplace sequences of with the emphasize on the simplest nontrivial case of period 2. For 3-component systems in Riemann invariants a complete description of closed quadruples is proposed. They turn to be related to a special quadratic reduction of the (2+1)-dimensional 3-wave system which can be reduced to a triple of pairwize commuting Monge-Ampere equations. In terms of the Lame and rotation coefficients Laplace transformations have a natural interpretation as the symmetries of the Dirac operator, associated with the (2+1)-dimensional n-wave system. The 2-component Laplace...
Long-time Behavior of Isolated Periodically Driven Interacting Lattice Systems
D'Alessio, Luca; Rigol, Marcos
2014-10-01
We study the dynamics of isolated interacting spin chains that are periodically driven by sudden quenches. Using full exact diagonalization of finite chains, we show that these systems exhibit three distinct regimes. For short driving periods, the Floquet Hamiltonian is well approximated by the time-averaged Hamiltonian, while for long periods, the evolution operator exhibits properties of random matrices of a circular ensemble (CE). In between, there is a crossover regime. Based on a finite-size scaling analysis and analytic arguments, we argue that, for thermodynamically large systems and nonvanishing driving periods, the evolution operator always exhibits properties of the CE of random matrices. Consequently, the Floquet Hamiltonian is a nonlocal Hamiltonian with multispin interaction terms, and the driving leads to the equivalent of an infinite temperature state at long times. These results are connected to the breakdown of the Magnus expansion and are expected to hold beyond the specific lattice model considered.
Directory of Open Access Journals (Sweden)
XU Tian-hua
2009-06-01
Full Text Available A competitive Lotka-volterra systemwith diffusion and infinite distributed delays is investigated. It is shown that the globally asymptotically stable trivial solution, when r1(ai>=0,(i=1,2,the globally asymptotically stable semi-trivial periodic solution(r1(t,x,,and 0,r2(t,x when p1(a1=0,p1(a2<0 of the models byconstruction of a pair of upper and lower solution (u1,u2,(0,0of parabolic periodic system (aui(t,x/at-Aiui(t,x=ui(t,x[ai(t,x-bi(t,xui(t,x],and in the use of eigenvalue theory and comparison principle. A T-periodic series are established by using the monotone iteration technique. It was obtained that the systems have a pair of periodic positive solutions with respect to every nonnegative initial function.
Gabale, Amit P.; Sinha, S. C.
2011-05-01
A methodology for determining reduced order models of periodically excited nonlinear systems with constant as well as periodic coefficients is presented. The approach is based on the construction of an invariant manifold such that the projected dynamics is governed by a fewer number of ordinary differential equations. Due to the existence of external and parametric periodic excitations, however, the geometry of the manifold varies with time. As a result, the manifold is constructed in terms of temporal and dominant state variables. The governing partial differential equation (PDE) for the manifold is nonlinear and contains time-varying coefficients. An approximate technique to find solution of this PDE using a multivariable Taylor-Fourier series is suggested. It is shown that, in certain cases, it is possible to obtain various reducibility conditions in a closed form. The case of time-periodic systems is handled through the use of Lyapunov-Floquet (L-F) transformation. Application of the L-F transformation produces a dynamically equivalent system in which the linear part of the system is time-invariant; however, the nonlinear terms get multiplied by a truncated Fourier series containing multiple parametric excitation frequencies. This warrants some structural changes in the proposed manifold, but the solution procedure remains the same. Two examples; namely, a 2-dof mass-spring-damper system and an inverted pendulum with periodic loads, are used to illustrate applications of the technique for systems with constant and periodic coefficients, respectively. Results show that the dynamics of these 2-dof systems can be accurately approximated by equivalent 1-dof systems using the proposed methodology.
Occurrence of periodic Lam\\'e functions at bifurcations in chaotic Hamiltonian systems
Brack, Matthias; Mehta, Mitaxi; Tanaka, Kaori
2001-01-01
We investigate cascades of isochronous pitchfork bifurcations of straight-line librating orbits in some two-dimensional Hamiltonian systems with mixed phase space. We show that the new bifurcated orbits, which are responsible for the onset of chaos, are given analytically by the periodic solutions of the Lam\\'e equation as classified in 1940 by Ince. In Hamiltonians with C_${2v}$ symmetry, they occur alternatingly as Lam\\'e functions of period 2K and 4K, respectively, where ...
Yang, Xiaosen
2014-01-01
We propose a simple approach to realize two-dimensional Floquet topological superfluid by periodically tuning the depth of square optical lattice potentials. We show that the periodic driving can induce topological phase transitions between trivial superfluid and Floquet topological superfluid. For this systems we verify the anomalous bulk-boundary correspondence, namely that the robust chiral Floquet edge states can appear even when the winding number of all the bulk Floque...
RICE, D; Barone, S.
2000-01-01
Vulnerable periods during the development of the nervous system are sensitive to environmental insults because they are dependent on the temporal and regional emergence of critical developmental processes (i.e., proliferation, migration, differentiation, synaptogenesis, myelination, and apoptosis). Evidence from numerous sources demonstrates that neural development extends from the embryonic period through adolescence. In general, the sequence of events is comparable among species, although t...
Jung, Soyeun
2012-01-01
In the previous paper \\cite{J1}, we established pointwise bounds for the Green function of the linearized equation associated with spatially periodic traveling waves $\\bar u$ of a system of reaction diffusion equations, and also obtained pointwise nonlinear stability and behavior of $\\bar u$ under small perturbations. In this paper, using periodic resolvent kernels and the Bloch-decomposition, we establish pointwise bounds for the Green function of the linearized equation as...
Soliton excitations and periodic waves without dispersion relation in shallow water system
International Nuclear Information System (INIS)
Using the nonstandard and standard truncations of a modified Conte's invariant Painleve expansion for the dispersive long wave equation system, two types of soliton excitations without any dispersive relations are found. Four types of periodic waves expressed by Jacobi elliptic functions are found by the truncations of a special extended Painleve expansion. The soliton solutions are special cases of the corresponding two of the given periodic solutions. The dispersion relations of the solutions are crucially dependent on the boundary conditions
Instability conditions for some periodic BGK waves in the Vlasov-Poisson system
Pankavich, Stephen; Allen, Robert
2014-12-01
A one-dimensional, collisionless plasma given by the Vlasov-Poisson system is considered and the stability properties of periodic steady state solutions known as Bernstein-Greene-Kruskal (BGK) waves are investigated. Sufficient conditions are determined under which BGK waves are linearly unstable under perturbations that share the same period as the equilibria. It is also shown that such solutions cannot support a monotonically decreasing particle distribution function.
DISK-PLANETS INTERACTIONS AND THE DIVERSITY OF PERIOD RATIOS IN KEPLER'S MULTI-PLANETARY SYSTEMS
International Nuclear Information System (INIS)
The Kepler mission is dramatically increasing the number of planets known in multi-planetary systems. Many adjacent planets have orbital period ratios near resonant values, with a tendency to be larger than required for exact first-order mean-motion resonances. This feature has been shown to be a natural outcome of orbital circularization of resonant planetary pairs due to star-planet tidal interactions. However, this feature holds in multi-planetary systems with periods longer than 10 days, in which tidal circularization is unlikely to provide efficient divergent evolution of the planets' orbits to explain these orbital period ratios. Gravitational interactions between planets and their parent protoplanetary disk may instead provide efficient divergent evolution. For a planet pair embedded in a disk, we show that interactions between a planet and the wake of its companion can reverse convergent migration and significantly increase the period ratio from a near-resonant value. Divergent evolution due to wake-planet interactions is particularly efficient when at least one of the planets opens a partial gap around its orbit. This mechanism could help account for the diversity of period ratios in Kepler's multiple systems from super-Earth to sub-Jovian planets with periods greater than about 10 days. Diversity is also expected for pairs of planets massive enough to merge their gap. The efficiency of wake-planet interactions is then much reduced, but convergent migration may stall with a variety of period ratios depending on the density structure in the common gap. This is illustrated for the Kepler-46 system, for which we reproduce the period ratio of Kepler-46b and c
International Nuclear Information System (INIS)
We present period change rates (dP/dt) for 42 RR Lyrae variables in the globular cluster IC 4499. Despite clear evidence of these period increases or decreases, the observed period change rates are an order of magnitude larger than predicted from theoretical models of this cluster. We find that there is a preference for increasing periods, a phenomenon observed in most RR Lyrae stars in Milky Way globular clusters. The period change rates as a function of position in the period-amplitude plane are used to examine possible evolutionary effects in OoI clusters, OoII clusters, field RR Lyrae stars, and the mixed-population cluster ? Centauri. It is found that there is no correlation between the period change rate and the typical definition of Oosterhoff groups. If the RR Lyrae period changes correspond with evolutionary effects, this would be in contrast to the hypothesis that RR Lyrae variables in OoII systems are evolved horizontal-branch stars that spent their zero-age horizontal-branch phase on the blue side of the instability strip. This may suggest that age may not be the primary explanation for the Oosterhoff types.
Directory of Open Access Journals (Sweden)
Y. Saiki
2007-09-01
Full Text Available An infinite number of unstable periodic orbits (UPOs are embedded in a chaotic system which models some complex phenomenon. Several algorithms which extract UPOs numerically from continuous-time chaotic systems have been proposed. In this article the damped Newton-Raphson-Mees algorithm is reviewed, and some important techniques and remarks concerning the practical numerical computations are exemplified by employing the Lorenz system.
Period Correction and Evolutionary Status of the MACHO Eclipsing Binary System 47.2135.29
Nematollah Riazi; Maysam Rezvani
2014-01-01
The eclipsing binary system which is catalogued in MACHO as 47.2135.29 is analyzed in detail for orbital elements and absolute parameters based on the MACHO observations and the latest values for the distance modulus of LMC. The period of the system is found more accurately, by minimizing the dispersion in the folded light curves. The binary is found to be a young semi-detached binary and is potentially a beta Lyrae system.
Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor-Blade Systems
DEFF Research Database (Denmark)
Christensen, Rene Hardam; Santos, Ilmar
2003-01-01
The demands for high efficiency machines initiate a demand for monitoring and active control of vibrations to improve machinery performance and to prolong machinery lifetime. Applying active control to reduce vibrations in flexible bladed rotor-systems imply that several difficulties have to be overcome. Among others it is necessary, that the control scheme is capable to cope with non-linear time-varying dynamical system behaviour. However, rotating at constant speed the mathematical model becomes periodic time-variant. In this framework the present paper gives a contribution to design procedures of active modal controllers. The main aim is to reduce vibrations in periodic time-varying structures. Special emphasis is given to vibration control of coupled bladed rotor systems. A state feedback modal control law is developed based on modal analysis in periodic time-varying structures. The first step in the procedure is a transformation of the model into a time-invariant modal form by applying the modal matrices, which are also periodic time-variant. Due to coupled rotor and blade motions complex vibration modes occur in the modal transformed state space model. This implies that the modal transformed model is reformulated using complex mode theory. Next, a linear constant gain controller for the reformulated system is designed by linear control technique. Finally, this constant gain controller is transformed to a time-periodic form by applying reverse modal transformation. The non-measurable states are estimated using a periodic time-varying state observer designed by a methodology similar to the controller design. Furthermore, the modal matrices are used to analyse the controllability of the system in order to determine optimal actuator placement in the system. For this the modal transform technique is a very effective tool. The control design methodology is applied to a coupled rotor-blade system to demonstrate the efficiency of such a procedure. A simulation model for the system is formulated and a time-periodic modal controller is designed using the described methodology. Simulation results are provided to demonstrate the applicability and effectiveness of the technique. The results obtained shows that the control design technique is capable to cope with the time periodicity of this class of systems.
Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor Blade Systems
DEFF Research Database (Denmark)
Christensen, Rene Hardam; Santos, Ilmar
2004-01-01
The demands for high efficiency machines initiate a demand for monitoring and active control of vibrations to improve machinery performance and to prolong machinery lifetime. Applying active control to reduce vibrations in flexible bladed rotor-systems imply that several difficulties have to be overcome. Among others it is necessary, that the control scheme is capable to cope with non-linear time-varying dynamical system behaviour. However, rotating at constant speed the mathematical model becomes periodic time-variant. In this framework the present paper gives a contribution to design procedures of active modal controllers. The main aim is to reduce vibrations in periodic time-varying structures. Special emphasis is given to vibration control of coupled bladed rotor systems. A state feedback modal control law is developed based on modal analysis in periodic time-varying structures. The first step in the procedure is a transformation of the model into a time-invariant modal form by applying the modal matrices, which are also periodic time-variant. Due to coupled rotor and blade motions complex vibration modes occur in the modal transformed state space model. This implies that the modal transformed model is reformulated using complex mode theory. Next, a linear constant gain controller for the reformulated system is designed by linear control technique. Finally, this constant gain controller is transformed to a time-periodic form by applying reverse modal transformation. The non-measurable states are estimated using a periodic time-varying state observer designed by a methodology similar to the controller design. Furthermore, the modal matrices are used to analyse the controllability of the system in order to determine optimal actuator placement in the system. For this the modal transform technique is a very effective tool. The control design methodology is applied to a coupled rotor-blade system to demonstrate the efficiency of such a procedure. A simulation model for the system is formulated and a time-periodic modal controller is designed using the described methodology. Simulation results are provided to demonstrate the applicability and effectiveness of the technique. The results obtained shows that the control design technique is capable to cope with the time periodicity of this class of systems.
From the counting room: Periodic performance checks on germanium gamma-ray-spectroscopy systems
International Nuclear Information System (INIS)
Periodic performance checks of germanium gamma-ray-spectroscopy systems are an essential part of a measurements quality assurance program. The reasons for doing periodic performance checks on a spectroscopy system are to demonstrate continuity between system calibrations and to alert the analyst to adverse changes in the system. It is essential to monitor the overall performance of a system and it is desirable to have a procedure which indicates which component of a system is causing deviations if any are observed. There are several tasks that could be included under the general classification of periodic performance checks: routine check-source counting, blind-sample analysis, and possibly system recalibration. Data from all of these tasks can be used to demonstrate accuracy and continuity of performance. Routine check-source counting or routine performance checks are discussed in two widely used references. This article will present a few additional ideas on system efficiency checks and refer the reader to the ANSI standard for energy calibration checks. The routine performance checks discussed in the references are counts of a check source which is in a geometry different from the sample geometries (nonsample-geometry source) such as a point or a button source. This article will discuss which system parameters this type of counting monitors and then point out some other parameters which must be monitored by other tasks
A Moebius-Strip Representation of the Matrix-Product Periodic System of Diatomic Molecules
Hefferlin, Ray
2007-04-01
Periodic systems of diatomic and triatomic molecules are well tested and documented [1]. The 3D form of the diatomic system consists of blocks, each having all molecules with two fixed-row atoms, on which the molecules are addressed by their atomic group numbers. The blocks can be replaced by tori [2], but in either case many redundancies exist (e.g., CO and OC). The tori [3] may be replaced by Moebius strips [4] which remove the redundancies. This representation of the periodic system will be presented. [1] Hefferlin, R., ``The Periodic Systems of Molecules, Presuppositions, Problems, and Prospects,'' Baird, D., Scerri, E., and McIntyre, L., Editors, Philosophy of Chemistry, Boston Studies in the Philosophy of Science, Springer, Dodrecht, the Netherlands, 2006. [2] Hefferlin, R,. ``Matrix-Product Periodic Systems of Molecules,'' J. Chem. Inf. Comput. Sci, 34, 314-317 (1994). [3] Hall, D. E, ``Quantitative Evaluation of Musical Scale Tunings,'' AJP, 42, 543-552 (1974). [4] Blau, S. K., ``Good Music unfolds in Small Steps,'' Physics Today, October 2006, pp. 19-21.
Periodic orbit analysis of a system with continuous symmetry-A tutorial.
Budanur, Nazmi Burak; Borrero-Echeverry, Daniel; Cvitanovi?, Predrag
2015-07-01
Dynamical systems with translational or rotational symmetry arise frequently in studies of spatially extended physical systems, such as Navier-Stokes flows on periodic domains. In these cases, it is natural to express the state of the fluid in terms of a Fourier series truncated to a finite number of modes. Here, we study a 4-dimensional model with chaotic dynamics and SO(2) symmetry similar to those that appear in fluid dynamics problems. A crucial step in the analysis of such a system is symmetry reduction. We use the model to illustrate different symmetry-reduction techniques. The system's relative equilibria are conveniently determined by rewriting the dynamics in terms of a symmetry-invariant polynomial basis. However, for the analysis of its chaotic dynamics, the "method of slices," which is applicable to very high-dimensional problems, is preferable. We show that a Poincaré section taken on the "slice" can be used to further reduce this flow to what is for all practical purposes a unimodal map. This enables us to systematically determine all relative periodic orbits and their symbolic dynamics up to any desired period. We then present cycle averaging formulas adequate for systems with continuous symmetry and use them to compute dynamical averages using relative periodic orbits. The convergence of such computations is discussed. PMID:26232963
Periodic orbit analysis of a system with continuous symmetry—A tutorial
Budanur, Nazmi Burak; Borrero-Echeverry, Daniel; Cvitanovi?, Predrag
2015-07-01
Dynamical systems with translational or rotational symmetry arise frequently in studies of spatially extended physical systems, such as Navier-Stokes flows on periodic domains. In these cases, it is natural to express the state of the fluid in terms of a Fourier series truncated to a finite number of modes. Here, we study a 4-dimensional model with chaotic dynamics and SO(2) symmetry similar to those that appear in fluid dynamics problems. A crucial step in the analysis of such a system is symmetry reduction. We use the model to illustrate different symmetry-reduction techniques. The system's relative equilibria are conveniently determined by rewriting the dynamics in terms of a symmetry-invariant polynomial basis. However, for the analysis of its chaotic dynamics, the "method of slices," which is applicable to very high-dimensional problems, is preferable. We show that a Poincaré section taken on the "slice" can be used to further reduce this flow to what is for all practical purposes a unimodal map. This enables us to systematically determine all relative periodic orbits and their symbolic dynamics up to any desired period. We then present cycle averaging formulas adequate for systems with continuous symmetry and use them to compute dynamical averages using relative periodic orbits. The convergence of such computations is discussed.
Multi-Period Optimization for Voltage Control System in Transmission Grids
DEFF Research Database (Denmark)
Qin, Nan; Chen, Si
2015-01-01
Automatic Voltage Control (AVC) systems maintain the voltage in an acceptable range and minimize the power loss of the grid by coordinately regulating the controllable components. Switchable shunts and tap-able transformers are expected to be operated as few times as possible. This paper proposes a two-level, multi-period optimal reactive power flow approach. In the upper level, the real-time measurements and short-term forecasts are used as the inputs of the multi-period optimization for one hour with 15 minutes intervals, to minimize the operational cost, subjected to a certain constraints. In the lower level, the optimization is focused on the correction of the voltage violations every single minute based on data from the measurements and state estimation. The presented case study shows that the multi-period optimization in the upper level of AVC system can reduce adjustment times of the discrete components for saving the total operational cost.
Directory of Open Access Journals (Sweden)
Flashner Henryk
1997-01-01
Full Text Available A point mapping analysis is employed to investigate the stability of periodic systems. The method is applied to simplified rotorcraft models. The proposed approach is based on a procedure to obtain an analytical expression for the period-to-period mapping description of system's dynamics, and its dependence on system's parameters. Analytical stability and bifurcation conditions are then determined and expressed as functional relations between important system parameters. The method is applied to investigate the parametric stability of flapping motion of a rotor and the ground resonance problem encountered in rotorcraft dynamics. It is shown that the proposed approach provides very accurate results when compared with direct numerical results which are assumed to be an “exact solution” for the purpose of this study. It is also demonstrated that the point mapping method yields more accurate results than the widely used classical perturbation analysis. The ability to perform analytical stability studies of systems with multiple degrees-of-freedom is an important feature of the proposed approach since most existing analysis methods are applicable to single degree-of-freedom systems. Stability analysis of higher dimensional systems, such as the ground resonance problems, by perturbation methods is not straightforward, and is usually very cumbersome.
Formation of nonlinear holographic images in a system of periodically located nonlinear mediums
Directory of Open Access Journals (Sweden)
Belkov S.A.
2013-11-01
Full Text Available The formation of nonlinear holographic images in a system of periodically located nonlinear mediums is studied. Analytical expressions which describe the magnitudes and locations of intensity maximums depending on the corresponding image number are derived. Comparison with numerical calculation results is presented.
Global Clock, Physical Time Order and Pending Period Analysis in Multiprocessor Systems
Chen, Yunji; Hu, Weiwu
2009-01-01
In multiprocessor systems, various problems are treated with Lamport's logical clock and the resultant logical time orders between operations. However, one often needs to face the high complexities caused by the lack of logical time order information in practice. In this paper, we utilize the \\emph{global clock} to infuse the so-called \\emph{pending period} to each operation in a multiprocessor system, where the pending period is a time interval that contains the performed time of the operation. Further, we define the \\emph{physical time order} for any two operations with disjoint pending periods. The physical time order is obeyed by any real execution in multiprocessor systems due to that it is part of the truly happened operation orders restricted by global clock, and it is then proven to be independent and consistent with traditional logical time orders. The above novel yet fundamental concepts enables new effective approaches for analyzing multiprocessor systems, which are named \\emph{pending period analy...
International Nuclear Information System (INIS)
Highlights: • A more practical form of harvesting management policy (DHP) has been proposed. • We analyze the periodic dynamics of a class of discontinuous and delayed Lotka–Volterra competition systems. • We present a new method to obtain the existence of positive periodic solutions via differential inclusions. • The global convergence in measure of harvesting solution is discussed. -- Abstract: This paper considers a general class of delayed Lotka–Volterra competition systems where the harvesting policies are modeled by discontinuous functions or by non-Lipschitz functions. By means of differential inclusions theory, cone expansion and compression fixed point theorem of multi-valued maps and nonsmooth analysis theory with generalized Lyapunov approach, a series of useful criteria on existence, uniqueness and global asymptotic stability of the positive periodic solution is established for the delayed Lotka–Volterra competition systems with discontinuous right-hand sides. Moreover, the global convergence in measure of harvesting solution is discussed. Our results improve and extend previous works on periodic dynamics of delayed Lotka–Volterra competition systems with not only continuous or even Lipschitz continuous but also discontinuous harvesting functions. Finally, we give some corollaries and numerical examples to show the applicability and effectiveness of the proposed criteria
A New Method for Studying the Periodic System Based on a Kohonen Neural Network
Chen, David Zhekai
2010-01-01
A new method for studying the periodic system is described based on the combination of a Kohonen neural network and a set of chemical and physical properties. The classification results are directly shown in a two-dimensional map and easy to interpret. This is one of the major advantages of this approach over other methods reported in the…
Existence of periodic solutions for non-autonomous second-order Hamiltonian systems
Yue Wu; Tianqing An
2013-01-01
The purpose of this paper is to study the existence of periodic solutions for a class of non-autonomous second order Hamiltonian systems. New results are obtained by using the least action principle and the minimax methods, without the so-called Ahmad-Lazer-Paul type condition.
Directory of Open Access Journals (Sweden)
Xinggui Liu
2011-01-01
Full Text Available In this paper, by using Mawhin's continuation theorem of coincidence degree theory, we establish the existence of at least four positive periodic solutions for a discrete time Lotka-Volterra competitive system with harvesting terms. An example is given to illustrate the effectiveness of our results.
Existence of Positive Periodic Solutions of a Lotka-Volterra System with Multiple Time Delays
Directory of Open Access Journals (Sweden)
Changjin Xu
2010-01-01
Full Text Available In this paper, a class of Lotka-Volterra system with multiple time delays is considered. By using the continuation theoremof coincidence degree theory, we derive a set of easily verifiable sucient conditions that guarantees the existence of atleast a positive periodic solution.
Existence of positive almost periodic solutions for delay Lotka-Volterra cooperative systems
Directory of Open Access Journals (Sweden)
Kaihong Zhao
2013-07-01
Full Text Available In this article, we study a Lotka-Volterra cooperative system of equations with time-varying delays and distributed delays. By using Mawhin's continuation theorem of coincidence degree theory, we obtain sufficient conditions for the existence of positive almost periodic solutions. Also we present an example to illustrate our results.
Existence of Positive Periodic Solutions of a Lotka-Volterra System with Multiple Time Delays
Changjin Xu; Maoxin Liao
2010-01-01
In this paper, a class of Lotka-Volterra system with multiple time delays is considered. By using the continuation theoremof coincidence degree theory, we derive a set of easily verifiable sucient conditions that guarantees the existence of atleast a positive periodic solution.
Existence of positive almost periodic solutions for delay Lotka-Volterra cooperative systems
Kaihong Zhao; Juqing Liu
2013-01-01
In this article, we study a Lotka-Volterra cooperative system of equations with time-varying delays and distributed delays. By using Mawhin's continuation theorem of coincidence degree theory, we obtain sufficient conditions for the existence of positive almost periodic solutions. Also we present an example to illustrate our results.
Czech Academy of Sciences Publication Activity Database
Domoshnitsky, A.; Hakl, Robert; Šremr, Ji?í
2012-01-01
Ro?. 112, May 22 (2012), s. 1-23. ISSN 1025-5834 Institutional support: RVO:67985840 Keywords : periodic problem * linear functional differential system * non-negative solution Subject RIV: BA - General Mathematics Impact factor: 0.879, year: 2010 http://www.journalofinequalitiesandapplications.com/content/2012/1/112
Infrared photometry of the RS CVn short-period systems - XY UMa and WY Cnc
International Nuclear Information System (INIS)
Infrared J and K light curves of two RS CVn short-period systems, XY UMa and WY Cnc, are presented. Both systems show similar variability in the infrared to that observed in the visual. From the colors an infrared excess is inferred for the primary component of both systems. A new determination of their geometrical elements is presented and the resulting parameters are compared to those previously obtained from visible photometry. The light curves show peculiarities that may indicate the presence of gas streams in the systems. 27 refs
Sign reversal of drag in bilayer systems with in-plane periodic potential modulation
DEFF Research Database (Denmark)
Alkauskas, A.; Flensberg, Karsten
2002-01-01
We develop a theory for describing frictional drag in bilayer systems with in-plane periodic potential modulations, and use it to investigate the drag between bilayer systems in which one of the layers is modulated in one direction. At low temperatures, as the density of carriers in the modulated layer is changed, we show that it is possible for the transresistivity component in the direction of modulation to change its sign. We also give a physical explanation for this behavior.
H2 OPTIMAL CONTROLLERS FOR A LARGE CLASS OF LINEAR STOCHASTIC SYSTEMS WITH PERIODIC COEFFICIENTS
Adrian-Mihail Stoica; Toader Morozan; Vasile Dragan
2011-01-01
In this paper the H2 type optimization problem for a class of timevarying linear stochastic systems modeled by Ito differential equations and Markovian jumping with periodic coefficients is considered. The main goal of such an optimization problem is to minimize the effect of additive white noise perturbations on a suitable output of the controlled system. It is assumed that only an output is available for measurements.The solution of the considered optimization problem is constructed via the...
The critical period of reservoir systems considering performance indices on Malaysia rivers
Issa Saket Oskoui; Rozi Abdullah; Majid Montaseri
2014-01-01
The behavior of reservoir systems can be investigated using Critical Period (CP) which determines the aggregation level of the data (monthly or annual) that are required to be utilized in the reservoir analysis. Currently there are a number of methods that could approximate the behavior of reservoir systems, however the efficiency of these approaches have not been studied and verified for the Malaysia Rivers. In this study two different hypothetical reservoirs on Malaysia Rivers are selected...
Orbital periods and Accretion disc structure of four AM CVn systems
Kupfer, T; Levitan, D; Steeghs, D; Marsh, T R; Rutten, R G M; Nelemans, G
2013-01-01
Phase-resolved spectroscopy of four AM CVn systems obtained with the William Herschel Telescope and the Gran Telescopio de Canarias (GTC) is presented. SDSS\\,J120841.96+355025.2 was found to have an orbital period of 52.96$\\pm$0.40\\,min and shows the presence of a second bright spot in the accretion disc. The average spectrum contains strong Mg\\,{\\sc i} and Si\\,{\\sc i/ii} absorption lines most likely originating in the atmosphere of the accreting white dwarf. SDSS\\,J012940.05+384210.4 has an orbital period of 37.555$\\pm$0.003 min. The average spectrum shows the Stark broadened absorption lines of the DB white dwarf accretor. The orbital period is close to the previously reported superhump period of 37.9\\,min. Combined, this results in a period excess $\\epsilon$=0.0092$\\pm$0.0054 and a mass ratio $q=0.031\\pm$0.018. SDSS\\,J164228.06+193410.0 displays an orbital period of 54.20$\\pm$1.60\\,min with an alias at 56.35\\,min. The average spectrum also shows strong Mg\\,{\\sc i} absorption lines, similar to SDSS\\,J120841...
Hillaire-Marcel, C.; Darby, D.; Francois, R.; Helie, J.; Lamziouaq, R.; Not, C.; Polyak, L.; Preda, M.; Satte, Y. M.; Stevenson, R.
2007-12-01
Sedimentological and geochemical properties, U-series isotopes, radiogenic isotopes and anthropogenic radionuclides contents were determined on two cores from the Mendeleev Ridge. Excesses in 210Pb over 226Ra activities are observed down to 1.25 cm from core-tops, due to shallow mixing by benthic organisms. Below, 210Pb-activity follows 226Ra-activity in turn controlled by parent 230Th-excess fluctuations in the sediment, except for some 226Ra-diffusion towards the water column from core-top and on both sides of 230Thxs peaks below. Thus, estimating 210Pb-excess requires precise knowledge of 226Ra-supported fraction, i.e., of 230Th- excess and Ra-diffusion. Both cores depict identical grain size, mineralogical, geochemical and isotopic distributions, despite bathymetric difference. This suggests negligible impact of bottom currents, limited scavenging of heavy metals in the lower water column, and a net export of particle reactive U-daughter isotopes (Th, Pa, Pb) produced from the overlying water column. Peaks in 230Thxs and 231Paxs (0-7cm, 17 cm and 30 cm sub-bottom) match high contents in clays and fine carbonates (primarily dolomite), and likely indicate interglacial/interstadial conditions and/or occurrence of turbidity events (e.g., during deglaciations). These peaks correspond to maximum illite supplies, minimum Sr-isotope ratios and epsilon-Nd values in the -10 to -12 range. Interlayered sediments, with high sand but low carbonate contents, minimum clay fluxes (low illite relative contents), minimum 230Th and 231Pa excesses, maximum Sr-isotope ratios, possibly indicate full glacial conditions and significantly reduced sedimentation rates.
Magnus' expansion for time-periodic systems: Parameter-dependent approximations
Butcher, Eric A.; Sari, Ma'en; Bueler, Ed; Carlson, Tim
2009-12-01
Magnus' expansion solves the nonlinear Hausdorff equation associated with a linear time-varying system of ordinary differential equations by forming the matrix exponential of a series of integrated commutators of the matrix-valued coefficient. Instead of expanding the fundamental solution itself, that is, the logarithm is expanded. Within some finite interval in the time variable, such an expansion converges faster than direct methods like Picard iteration and it preserves symmetries of the ODE system, if present. For time-periodic systems, Magnus expansion, in some cases, allows one to symbolically approximate the logarithm of the Floquet transition matrix (monodromy matrix) in terms of parameters. Although it has been successfully used as a numerical tool, this use of the Magnus expansion is new. Here we use a version of Magnus' expansion due to Iserles [Iserles A. Expansions that grow on trees. Not Am Math Soc 2002;49:430-40], who reordered the terms of Magnus' expansion for more efficient computation. Though much about the convergence of the Magnus expansion is not known, we explore the convergence of the expansion and apply known convergence estimates. We discuss the possible benefits to using it for time-periodic systems, and we demonstrate the expansion on several examples of periodic systems through the use of a computer algebra system, showing how the convergence depends on parameters.
DEFF Research Database (Denmark)
Rudner, Mark Spencer; Lindner, Netanel
2013-01-01
Recently, several authors have investigated topological phenomena in periodically driven systems of noninteracting particles. These phenomena are identified through analogies between the Floquet spectra of driven systems and the band structures of static Hamiltonians. Intriguingly, these works have revealed phenomena that cannot be characterized by analogy to the topological classification framework for static systems. In particular, in driven systems in two dimensions (2D), robust chiral edge states can appear even though the Chern numbers of all the bulk Floquet bands are zero. Here, we elucidate the crucial distinctions between static and driven 2D systems, and construct a new topological invariant that yields the correct edge-state structure in the driven case. We provide formulations in both the time and frequency domains, which afford additional insight into the origins of the “anomalous” spectra that arise in driven systems. Possibilities for realizing these phenomena in solid-state and cold-atomic systems are discussed.
Nabel, Elisa M; Morishita, Hirofumi
2013-01-01
Early temporary windows of heightened brain plasticity called critical periods developmentally sculpt neural circuits and contribute to adult behavior. Regulatory mechanisms of visual cortex development - the preeminent model of experience-dependent critical period plasticity-actively limit adult plasticity and have proved fruitful therapeutic targets to reopen plasticity and rewire faulty visual system connections later in life. Interestingly, these molecular mechanisms have been implicated in the regulation of plasticity in other functions beyond vision. Applying mechanistic understandings of critical period plasticity in the visual cortex to fear circuitry may provide a conceptual framework for developing novel therapeutic tools to mitigate aberrant fear responses in post traumatic stress disorder. In this review, we turn to the model of experience-dependent visual plasticity to provide novel insights for the mechanisms regulating plasticity in the fear system. Fear circuitry, particularly fear memory erasure, also undergoes age-related changes in experience-dependent plasticity. We consider the contributions of molecular brakes that halt visual critical period plasticity to circuitry underlying fear memory erasure. A major molecular brake in the visual cortex, perineuronal net formation, recently has been identified in the development of fear systems that are resilient to fear memory erasure. The roles of other molecular brakes, myelin-related Nogo receptor signaling and Lynx family proteins - endogenous inhibitors for nicotinic acetylcholine receptor, are explored in the context of fear memory plasticity. Such fear plasticity regulators, including epigenetic effects, provide promising targets for therapeutic interventions. PMID:24273519
Directory of Open Access Journals (Sweden)
HirofumiMorishita
2013-11-01
Full Text Available Early temporary windows of heightened brain plasticity called critical periods developmentally sculpt neural circuits and contribute to adult behavior. Regulatory mechanisms of visual cortex development –the preeminent model of experience-dependent critical period plasticity- actively limit adult plasticity and have proved fruitful therapeutic targets to reopen plasticity and rewire faulty visual system connections later in life. Interestingly, these molecular mechanisms have been implicated in the regulation of plasticity in other functions beyond vision. Applying mechanistic understandings of critical period plasticity in the visual cortex to fear circuitry may provide a conceptual framework for developing novel therapeutic tools to mitigate aberrant fear responses in post traumatic stress disorder. In this review, we turn to the model of experience-dependent visual plasticity to provide novel insights for the mechanisms regulating plasticity in the fear system. Fear circuitry, particularly fear memory erasure, also undergoes age-related changes in experience-dependent plasticity. We consider the contributions of molecular brakes that halt visual critical period plasticity to circuitry underlying fear memory erasure. A major molecular brake in the visual cortex, perineuronal net formation, recently has been identified in the development of fear systems that are resilient to fear memory erasure. The roles of other molecular brakes, myelin-related Nogo receptor signaling and Lynx family proteins– endogenous inhibitors for nicotinic acetylcholine receptor, are explored in the context of fear memory plasticity. Such fear plasticity regulators, including epigenetic effects, provide promising targets for therapeutic interventions.
Multistability and stable asynchronous periodic oscillations in a multiple-delayed neural system
Campbell, S. A.; Ncube, I.; Wu, J.
2006-02-01
We consider a network of three identical neurons with multiple discrete signal transmission delays. The model for such a network is a system of nonlinear delay differential equations. After some consideration of the absolute synchronization of the system and the global attractivity of the zero solution, we present a detailed discussion about the boundaries of the stability region of the trivial solution. This allows us to determine the possible codimension one bifurcations which occur in the system. In particular, we show the existence of standard Hopf bifurcations giving rise to synchronized periodic solutions and of D3 equivariant Hopf bifurcations giving rise to three types of periodic solutions: phase-locked, mirror-reflecting, and standing waves. Hopf-Hopf and Hopf-steady state bifurcations interactions are shown to exist and give rise to coexistence of stable synchronized and desynchronized solutions. Perturbation techniques coupled with the Floquet theory are used to determine the stability of the phase-locked oscillations.
Positive almost periodic solutions for state-dependent delay Lotka-Volterra competition systems
Directory of Open Access Journals (Sweden)
Yongkun Li
2012-06-01
Full Text Available In this article, using Mawhin's continuation theorem of coincidence degree theory, we obtain sufficient conditions for the existence of positive almost periodic solutions for the system of equations $$ dot{u}_i(t=u_i(tBig[r_i(t-a_{ii}(tu_i(t -sum_{j=1, jeq i}^na_{ij}(tu_jig(t-au_j(t,u_1(t, dots,u_n(tigBig], $$ where $r_i,a_{ii}>0$, $a_{ij}geq0(jeq i$, $i,j=1,2,dots,n$ are almost periodic functions, $au_iin C(mathbb{R}^{n+1},mathbb{R}$, and $au_i(i=1,2,dots,n$ are almost periodic in $t$ uniformly for $(u_1,dots,u_n^Tinmathbb{R}^n$. An example and its simulation figure illustrate our results.
Classification of the Floquet statistical distribution for time-periodic open systems
Liu, Dong E.
2015-04-01
How to understand the order of Floquet stationary states in the presence of external bath coupling and their statistical mechanics is challenging; the answers are important for preparation and control of those Floquet states. Here, we propose a scheme to classify the statistical distribution of Floquet states for time-periodic systems which couple to an external heat bath. If an effective Hamiltonian and a system-bath coupling operator, which are all time independent, can be simultaneously obtained via a time-periodic unitary transformation, the statistical mechanics of the Floquet states is equivalent to the equilibrium statistical mechanics of the effective Hamiltonian. In the large driving frequency cases, we also show that the conditions of this theorem can be weakened to the following: The time-period part in the system Hamiltonian commutes with the system-bath coupling operator. A Floquet-Markov approach is applied to numerically compute the Floquet state occupation distribution of a bosonic chain, and the results agree with the theoretical predictions.
Establishment of the optimal time interval between periodic inspections for redundant systems
International Nuclear Information System (INIS)
For redundant systems with periodic inspections, the establishment of the optimal time interval between inspections that maximize availability and minimize costs is a challenging issue. This paper develops a model to analyze the reliability and determine the optimal interval between inspections of redundant systems subjected to periodic inspections. It uses discrete time Markov Chains to define the transition probabilities between the state of the systems and the costs related with each state. To optimize the time between inspections, the total cost per cycle was minimized using the Markov Chain properties followed by a numerical search technique. Four models of systems are analyzed and numerical examples for systems comprised of two and three components are presented: Model I – Active redundancy without component repair; Model II – Active redundancy with component repair; Model III – Standby redundancy without component repair and Model IV – Standby redundancy with component repair. The main advantage of the model used in this paper is the inclusion of costs for unavailability and production losses through the definition of the downtime costs that penalize the model when the system fails. This model can also be extended and generalized to determine the optimal interval between inspections in systems with active or inactive redundancies and with n components
Reverse resonance in stock prices of financial system with periodic information
Li, Jiang-Cheng; Mei, Dong-Cheng
2013-07-01
We investigate the stochastic resonance of the stock prices in a finance system with the Heston model. The extrinsic and intrinsic periodic information are introduced into the stochastic differential equations of the Heston model for stock price by focusing on the signal power amplification (SPA). We find that for both cases of extrinsic and intrinsic periodic information a phenomenon of reverse resonance emerges in the behaviors of SPA as a function of the system and external driving parameters. Moreover, in both cases, a phenomenon of double reverse resonance is observed in the behavior of SPA versus the amplitude of volatility fluctuations, by increasing the cross correlation between the noise sources in the Heston model.
The effect of traffic light on accident probability in open and periodic boundaries system
Mhirech, Abdelaziz; Alaoui-Ismaili, Assia
2015-09-01
In this paper we numerically study the dependence of car accident probability Pac, per site and per time step on cycle time T of traffic light, both in open and periodic boundaries system. In this study one traffic light is placed in the middle of the system. This work is based on Nagel and Schreckenberg (NaSch) model (Nagel and Schreckenberg (1992)) in parallel dynamics. The Pac dependence on T and the (?, ?) phase diagrams are established. ? and ? are the injecting and extracting rates of cars in the traffic lane respectively. The increase of the cycle time light T causes an important decrease of the accident probability Pac both in the open and periodic cases.
International Nuclear Information System (INIS)
With the aim of formulating a method to control dynamic phase transitions in periodically driven bistable systems with reversal symmetry, a time-delayed feedback control method to stabilize an unstable periodic orbit in the broken symmetric regime is studied. In order to overcome a limitation of the conventional time-delayed feedback method, another extended scheme is proposed, and its improved ability with respect to stabilization is proved. Through the linear stability analysis of model controlled systems driven by sinusoidal fields, basic differences between the conventional and proposed methods are extracted. It is clarified that a few characteristics around the bifurcation point from the pitchfork critical branch to the Hopf branch and the turning point of the Hopf critical branch classify essential features of the stability diagram and concern restrictions for stabilization. Within the linear stability treatment, this paper estimates a safe choice and an effective range of feedback gains in the proposed method. (author)
Stability of Closed Loop Controlled Repetitive Periodic System applied to control of CD-Player
DEFF Research Database (Denmark)
Odgaard, Peter Fogh; Stoustrup, Jakob
2005-01-01
In this paper a criterion for stability of specific control scheme for handling linear dynamic control systems with repetitive periodic sensor faults is derived. The given system and control scheme are described and defined. By combining these with the lifting technique a necessary and sufficient stability criterion is derived. This criterion is following applied to an example on a feature based control scheme for handling CD-players playing CDs with surface faults. This feature based control scheme is handling repetitive periodic sensor faults. The feature based control scheme approximates the repetitive sensor faults (surface faults). The fault approximations are subsequently subtracted from the measurements, and the influence from these repetitive sensor faults are thereby removed from the computed control signals.
Periodic-orbit theory of the number variance ?2(L) of strongly chaotic systems
International Nuclear Information System (INIS)
We discuss the number variance ?2(L) and the spectral form factor F(?) of the energy levels of bound quantum systems whose classical counterparts are strongly chaotic. Exact periodic-orbit representations of ?2(L) and F(?) are derived which explain the breakdown of universality, i.e., the deviations from the predictions of random-matrix theory. The relation of the exact spectral form factor F(?) to the commonly used approximation K(?) is clarified. As an illustration the periodic-orbit representations are tested in the case of a strongly chaotic system at low and high energies including very long-range correlations up to L=700. Good agreement between 'experimental' data and theory is obtained. (orig.)
Partovi-Azar, Pouya
2015-01-01
We extend the method of Silvestrelli [P. L. Silvestrelli, J. Chem. Phys. 139, 054106 (2013)] to approximate long-range van der Waals interactions at the density functional theory level based on maximally localized Wannier functions combined with the quantum harmonic oscillator model, to periodic systems. Applying this scheme to study London dispersion forces between graphene and water layers, we demonstrate that collective many-body effects beyond simple additive pair-wise interactions are essential to accurately describe van der Waals forces.
Periodic systems of frustrated fluid films and « bicontinuous » cubic structures in liquid crystals
CHARVOLIN, J; Sadoc, J F
1987-01-01
We consider periodic organizations of two fluid media separated by interfaces in which interactions between the two media, normal to the interfaces, maintain constant distances between interfaces and constraints within each medium, parallel to the interfaces, control interfacial curvatures. The structures must therefore conciliate the constant interfacial distances and curvatures imposed by the thermodynamical parameters of the systems. This is a purely geometrical problem whose solutions con...
Time-periodic solutions to the full Navier–Stokes–Fourier system.
Czech Academy of Sciences Publication Activity Database
Feireisl, Eduard; Mucha, P.; Novotný, A.; Pokorný, M.
2012-01-01
Ro?. 204, ?. 3 (2012), s. 745-786. ISSN 0003-9527 R&D Projects: GA ?R GA201/09/0917; GA MŠk LC06052 Institutional research plan: CEZ:AV0Z10190503 Keywords : compressible Navier–Stokes–Fourier system * time-periodic solution * weak solution Subject RIV: BA - General Mathematics Impact factor: 2.292, year: 2012 http://www.springerlink.com/content/3t5r85w616158561/
Non-linear second-order periodic systems with non-smooth potential
Papageorgiou, Evgenia H; Papageorgiou, Nikolaos S.
2005-01-01
In this paper we study second order non-linear periodic systems driven by the ordinary vector $p$-Laplacian with a non-smooth, locally Lipschitz potential function. Our approach is variational and it is based on the non-smooth critical point theory. We prove existence and multiplicity results under general growth conditions on the potential function. Then we establish the existence of non-trivial homoclinic (to zero) solutions. Our theorem appears to be the first such result...
Eckardt, André; Anisimovas, Egidijus
2015-01-01
We derive a systematic high-frequency expansion for the effective Hamiltonian and the micromotion operator of periodically driven quantum systems. Our approach is based on the block diagonalization of the quasienergy operator in the extended Floquet Hilbert space by means of degenerate perturbation theory. The final results are equivalent to those obtained within a different approach [Phys.\\ Rev.\\ A {\\bf 68}, 013820 (2003), Phys.\\ Rev.\\ X {\\bf 4}, 031027 (2014)] and can also...
Partovi-Azar, Pouya; Kühne, T. D.
2015-01-01
We extend the method of Silvestrelli [P. L. Silvestrelli, J. Chem. Phys. 139, 054106 (2013)] to approximate long-range van der Waals interactions at the density functional theory level based on maximally localized Wannier functions combined with the quantum harmonic oscillator model, to periodic systems. Applying this scheme to study London dispersion forces between graphene and water layers, we demonstrate that collective many-body effects beyond simple additive pair-wise i...
Energy Technology Data Exchange (ETDEWEB)
Jin Zhen E-mail: jinzhn@263.net; Ma Zhien; Maoan Han
2004-10-01
In this paper, we study the existence of positive periodic solutions of periodic n-species Lotka-Volterra competition systems with impulses. By using the method coincidence degree theorem, a set of easily verifiable sufficient conditions are obtained for the existence of at least one strictly positive periodic solutions. Some known results are improved and generalized.
International Nuclear Information System (INIS)
In this paper, we study the existence of positive periodic solutions of periodic n-species Lotka-Volterra competition systems with impulses. By using the method coincidence degree theorem, a set of easily verifiable sufficient conditions are obtained for the existence of at least one strictly positive periodic solutions. Some known results are improved and generalized
THE HD 192263 SYSTEM: PLANETARY ORBITAL PERIOD AND STELLAR VARIABILITY DISENTANGLED
International Nuclear Information System (INIS)
As part of the Transit Ephemeris Refinement and Monitoring Survey, we present new radial velocities and photometry of the HD 192263 system. Our analysis of the already available Keck-HIRES and CORALIE radial velocity measurements together with the five new Keck measurements we report in this paper results in improved orbital parameters for the system. We derive constraints on the size and phase location of the transit window for HD 192263b, a Jupiter-mass planet with a period of 24.3587 ± 0.0022 days. We use 10 years of Automated Photoelectric Telescope photometry to analyze the stellar variability and search for planetary transits. We find continuing evidence of spot activity with periods near 23.4 days. The shape of the corresponding photometric variations changes over time, giving rise to not one but several Fourier peaks near this value. However, none of these frequencies coincides with the planet's orbital period and thus we find no evidence of star-planet interactions in the system. We attribute the ?23 day variability to stellar rotation. There are also indications of spot variations on longer (8 years) timescales. Finally, we use the photometric data to exclude transits for a planet with the predicted radius of 1.09 RJ , and as small as 0.79 RJ .
Ionization of Coulomb systems in $\\RR^3$ by time periodic forcings of arbitrary size
Costin, O.; Lebowitz, J. L.; Tanveer, S
2006-01-01
We analyze the long time behavior of solutions of the Schr\\"odinger equation $i\\psi_t=(-\\Delta-b/r+V(t,x))\\psi$, $x\\in\\RR^3$, $r=|x|$, describing a Coulomb system subjected to a spatially compactly supported time periodic potential $V(t,x)=V(t+2\\pi/\\omega,x)$ with zero time average. We show that, for any $V(t,x)$ of the form $2\\Omega(r)\\sin (\\omega t-\\theta)$, with $\\Omega(r)$ nonzero on its support, Floquet bound states do not exist. This implies that the system ionizes, {\\...
Periodic Density Modulation Effects on a Correlated two-dimensional Composite Fermion System
Sakhi, S
2001-01-01
We examine theoretically the effects caused by a periodic external potential on the correlated motion of a two-dimensional electron system under strong magnetic fields corresponding to a filling factor 1/2. To describe the resulting complex dynamics, we adopt a composite fermion approach and we determine in a two loop approximation the density-response function $K_{00}(\\bfq,\\omega)$ and the compressibility. We show explicitly that the long-wavelength limit of $K_{00}(\\bfq,\\omega)$ exhibits substantial anisotropic behavior induced by the modulation, and that the system tends to be incompressible in a direction orthogonal to the modulation as opposed to its response along the modulation.
Optimal selection of pit haulage system in transition period for mining-in-areas
Energy Technology Data Exchange (ETDEWEB)
Shang, T.; Cai, Q.; Liu, X.; Xu, Z. [CUMT, Xuzhou (China). School of Mineral and Safety Engineering
2004-07-01
Taking ATB surface mine, Pingshuo Coal Company as an example, the feature of pit haulage system was analysed in the transition period for mining-in-areas at flat-bedded or gently-inclined deposit. Methods for optimizing pit haulage system were proposed. According to dumping sites and their volumes, the best haulage paths for overburden from different bench areas were optimized. Other measures were suggested such as faster advancing the upper benches in the old mining areas. 5 refs., 3 figs., 2 tabs.
The Effects of Systemic Banking Crises in the Inter-War Period
Rocha, Bruno; Solomou, Solomos
2015-01-01
This paper examines the time-profile of the impact of systemic banking crises on GDP and industrial production using a panel of 24 countries over the inter-war period and compares this to the post-war experience of these countries. We show that banking crises have effects that induce medium-term adjustments on economies. Focusing on an eight-year horizon, it is clear that the negative effects of systemic banking crises last over the entirety of this time-horizon. The effect has been identifie...
Evaluation of raw milk quality in different production systems and periods of the year
Scientific Electronic Library Online (English)
Marcos Inácio, Marcondes; Daniele Canabrava, Jácome; Alex Lopes da, Silva; Luciana Navajas, Rennó; Ana Clarissa dos Santos, Pires.
2014-12-01
Full Text Available The objective of this study was to evaluate the quality of raw milk in different production systems and its variation throughout the year. The data were collected from 943 dairy farms in the South, Central-West and Central regions of the state of Minas Gerais, and in Vale do Paraíba, in the state of [...] São Paulo, Brazil. The data were collected in the period from January 2009 to September 2011, in a total of 18,206 samples. The properties were divided into confinement, semi-confinement and extensive production systems. The evaluated factors were somatic cell count (SCC), total bacterial count (TBC) and protein and fat contents. There was no effect of production system on the contents of protein, fat and SCC. Total bacterial count, however, was affected by production. Seasonal variations were found for SCC, TBC, protein and fat; the highest protein values were found from March to June; the highest fat contents were obtained from May to August; and TBC and SCC, from December to March. The production system does not interfere with the percentage of fat and protein and SCC of the milk. However, confinement systems present a better TBC content. Both month and year are factors that interfere with TBC, SCC, protein and milk fat, and the best patterns are found in the coldest periods of the year.
Markov analysis of redundant standby safety systems under periodic surveillance testing
International Nuclear Information System (INIS)
In modern applications of probabilistic safety assessment (PSA), maintenance planning and changes to technical specifications play an important role, not least due to regulatory requirements. In particular, standby safety systems under periodic surveillance testing are at the center of this issue. Since traditional PSA techniques impose limitations when complex maintenance and repair strategies are to be taken explicitly into account, we introduce continuous time Markov models to discuss various strategies for organizing repair and testing of two-train standby safety systems, which have the potential to replace traditional system models based on fault tree techniques in PSA. Besides a conventional steady state analysis of these Markov models, we provide a general numerical method which allows the calculation of the probability of exceeding allowed outage times of equipment in Markov models of safety systems, and we apply it to the models introduced in the present paper. - Highlights: • We consider Markov models of systems under periodic surveillance testing. • Besides the steady state availability we consider the probability of exceeding allowed outage times of equipment. • We provide a general method to calculate the probability of exceeding allowed outage times for Markov models
International Nuclear Information System (INIS)
A common scenario in engineering is that of a system which operates throughout several sequential and distinct periods of time, during which the modes and consequences of failure differ from one another. This type of operation is known as a phased mission, and for the mission to be a success the system must successfully operate throughout all of the phases. Examples include a rocket launch and an aeroplane flight. Component or sub-system failures may occur at any time during the mission, yet not affect the system performance until the phase in which their condition is critical. This may mean that the transition from one phase to the next is a critical event that leads to phase and mission failure, with the root cause being a component failure in a previous phase. A series of phased missions with no maintenance may be considered as a maintenance-free operating period (MFOP). This paper describes the use of a Petri net (PN) to model the reliability of the MFOP and phased missions scenario. The model uses Monte-Carlo simulation to obtain its results, and due to the modelling power of PNs, can consider complexities such as component failure rate interdependencies and mission abandonment. The model operates three different types of PN which interact to provide the overall system reliability modelling. The model is demonstrated and validated by considering two simple examples that can be solved analytically
Linear response as a singular limit for a periodically driven closed quantum system
International Nuclear Information System (INIS)
We address the issue of the validity of linear response theory for a closed quantum system subject to a periodic external driving. Linear response theory (LRT) predicts energy absorption at frequencies of the external driving where the imaginary part of the appropriate response function is different from zero. Here we show that, for a fairly general nonlinear many-body system on a lattice subject to an extensive perturbation, this approximation should be expected to be valid only up to a time t* depending on the strength of the driving, beyond which the true coherent Schrödinger evolution departs from the linear response prediction and the system stops absorbing energy from the driving. We exemplify this phenomenon in detail with the example of a quantum Ising chain subject to a time-periodic modulation of the transverse field, by comparing an exact Floquet analysis with the standard results of LRT. In this context, we also show that if the perturbation is just local, the system is expected in the thermodynamic limit to keep absorbing energy, and LRT works at all times. We finally argue more generally the validity of the scenario presented for closed quantum many-body lattice systems with a bound on the energy-per-site spectrum, discussing the experimental relevance of our findings in the context of cold atoms in optical lattices and ultra-fast spectroscopy experiments. (paper)
Internal Space-time Symmetries of Particles derivable from Periodic Systems in Optics
Kim, Y S
2010-01-01
While modern optics is largely a physics of harmonic oscillators and two-by-two matrices, it is possible to learn about some hidden properties of the two-by-two matrix from optical systems. Since two-by-two matrices can be divided into three conjugate classes depending on their traces, optical systems force us to establish continuity from one class to another. It is noted that those three classes are equivalent to three different branches of Wigner's little groups dictating the internal space-time symmetries massive, massless, and imaginary-mass particles. It is shown that the periodic systems in optics can also be described by have the same class-based matrix algebra. The optical system allow us to make continuous, but not analytic, transitions from massiv to massless, and massless to imaginary-mass cases.
International Nuclear Information System (INIS)
A comprehensive presentation of a new approach to finite periodic systems is given. The novel and general expressions obtained here, allow simple and precise calculations of various physical quantities characteristic of crystalline systems. Transmission amplitudes through n-cell multichannel quantum systems are rigorously derived. General expressions for several physical quantities are entirely expressed in terms of single-cell amplitudes and a new class of polynomials pN,n. Besides the general expressions, we study some superlattice properties as the band structure and its relation with the phase coherence phenomena, the level density and the Kronig-Penney model as its continuous espectrum limit. Bandstructure tailoring, optical multilayer systems, resonant energies and functions and channel-mixing effects in multichannel transport process are also analysed in the light of the new approach. (author)
Inventory of thermal solar energy systems in the Netherlands: Period 1975-1992
International Nuclear Information System (INIS)
An overview is given of the number of active thermal solar energy systems that have been installed in the Netherlands during the period 1975-1992. By the end of 1992, 8,300 systems have been installed, of which 6,000 were domestic solar hot water systems. The uncertainty in these figures is 10%. Several sources were used to determine the number of systems installed. The two main sources were the files of the solar industry association 'Holland Solar' (data until 1988), and the Dutch subsidy administrator 'Senter' for data from 1988 up to and including 1992. At the end of 1992 preparations were made for the installation of approximately 3,000 domestic solar water heaters in 1993. It is recommended to carry out an inventory every three months and to compile data on investment costs. 17 figs., 7 appendices
Periodic mesoporous silica monoliths templated by liquid crystals in complex systems
Feng, Pingyun; Bu, Xianhui; Stucky, Galen D.; Pine, David J.
2000-04-01
Periodic mesoporous oxides are usually synthesized from water/surfactant system with low surfactant concentrations and 1,3,5-trimethylbenzene has been sued as a swelling agent to increase the spore size under certain conditions. The use of pre-formed liquid crystal phases as template in multicomponent system holds promise for even large pore sizes, large monoliths, and a high level of phase, pore size, and morphology control. Here a generalized method has ben employed to prepare liquid crystal phase that subsequently act as template for the formation of periodic mesoporous silica. Once formed, liquid crystal phases persist throughout the inorganic polymerization and gelation processes and directly template the formation of inorganic mesophases. The method is applicable to a diversity of chemical compositions and offers a simultaneous control over the pore size and morphology. Synthetic variables that can be used to tune the pore size include cosurfactant chain length, cosurfactant/surfactant mass ratios, and the amount of oil. The removal of organic components leads to periodic mesoporous silica with excellent thermal and hydrothermal stability.
Self-isospectral tri-supersymmetry in PT-symmetric quantum systems with pure imaginary periodicity
International Nuclear Information System (INIS)
We study a reflectionless PT-symmetric quantum system described by the pair of complexified Scarf II potentials mutually displaced in the half of their pure imaginary period. Analyzing the rich set of intertwining discrete symmetries of the pair, we find an exotic supersymmetric structure based on three matrix differential operators that encode all the properties of the system, including its reflectionless (finite-gap) nature. The structure we revealed particularly sheds new light on the splitting of the discrete states into two families, related to the bound and resonance states in Hermitian Scarf II counterpart systems, on which two different series of irreducible representations of sl(2,C) are realized. - Highlights: ? A two-parametric family of pairs of reflectionless self-isospectral PT-symmetric systems is studied. ? A new exotic supersymmetric structure based on three integrals of motion is found. ? The splitting of the discrete states into two families is explained. ? The role of various discrete symmetries and the imaginary period is understood.
Gap opening and split band edges in waveguides coupled by a periodic system of small windows
Borisov, D
2012-01-01
At the example of two coupled waveguides we construct a periodic second order differential operator acting in a Euclidean domain and having spectral gaps whose edges are attained strictly inside the Brillouin zone. The waveguides are modeled by the Laplacian in two infinite strips of different width that have a common interior boundary. On this common boundary we impose the Neumann boundary condition but cut out a periodic system of small holes, while on the remaining exterior boundary we impose the Dirichlet boundary condition. It is shown that, by varying the widths of the strips and the distance between the holes, one can control the location of the extrema of the band functions as well as the number of the open gaps. We calculate the leading terms in the asymptotics for the gap lengths and the location of the extrema.
Rui Xu; Qiming Liu
2003-01-01
A delayed three-species periodic food-chain system with Holling type-II functional response is investigated. By using Gaines and Mawhin's continuation theorem of coincidence degree theory, a set of easily verifiable sufficient conditions is derived for the existence of positive periodic solutions to the system.
Johnson, Mathew A.; Zumbrun, Kevin
2010-01-01
Extending previous results of Oh--Zumbrun and Johnson--Zumbrun, we show that spectral stability implies linearized and nonlinear stability of spatially periodic traveling-wave solutions of viscous systems of conservation laws for systems of generic type, removing a restrictive assumption that wave speed be constant to first order along the manifold of nearby periodic solutions.
Range-separated double-hybrid density-functional theory applied to periodic systems
Sansone, Giuseppe; Civalleri, Bartolomeo; Usvyat, Denis; Toulouse, Julien; Sharkas, Kamal; Maschio, Lorenzo
2015-09-01
Quantum chemistry methods exploiting density-functional approximations for short-range electron-electron interactions and second-order Møller-Plesset (MP2) perturbation theory for long-range electron-electron interactions have been implemented for periodic systems using Gaussian-type basis functions and the local correlation framework. The performance of these range-separated double hybrids has been benchmarked on a significant set of systems including rare-gas, molecular, ionic, and covalent crystals. The use of spin-component-scaled MP2 for the long-range part has been tested as well. The results show that the value of ? = 0.5 bohr-1 for the range-separation parameter usually used for molecular systems is also a reasonable choice for solids. Overall, these range-separated double hybrids provide a good accuracy for binding energies using basis sets of moderate sizes such as cc-pVDZ and aug-cc-pVDZ.
Tunneling Dynamics of Dipolar Bosonic System with Periodically Modulated s-wave Scattering
International Nuclear Information System (INIS)
Within the mean-field three-site Bose—Hubbard model, the tunneling dynamics of dipolar bosonic gas with a periodically modulation of s-wave scattering is investigated. The system experiences complex and rich coherent tunneling (CT)-coherent destruction of tunneling (CDT) transitions resulting from the correlated effect among the next-neighbor dipole-dipole interaction, the on-site interaction and the modulated s-wave scattering. In particular, The region of the modulated s-wave scattering for generating CT (CDT) is the widest (narrowest) when the on-site interaction and the next-neighbor dipole-dipole interaction have some correlated values, which are closely related to the tunneling energy and the interaction energy of the system. The correlated values for appearing CDT can be theoretically gained from the tunneling energy and the interaction energy of the system. (general)
Soliton defects in one-gap periodic system and exotic supersymmetry
Arancibia, Adrian; Jakubsky, Vit; Guilarte, Juan Mateos; Plyushchay, Mikhail S
2014-01-01
By applying Darboux-Crum transformations to the quantum one-gap Lame system, we introduce an arbitrary countable number of bound states into forbidden bands. The perturbed potentials are reflectionless and contain two types of soliton defects in the periodic background. The bound states with finite number of nodes are supported in the lower forbidden band by the periodicity defects of the potential well type, while the pulse type bound states in the gap have infinite number of nodes and are trapped by defects of the compression modulations nature. We investigate the exotic nonlinear N=4 supersymmetric structure in such paired Schrodinger systems, which extends an ordinary N=2 supersymmetry and involves two bosonic generators composed from Lax-Novikov integrals of the subsystems. One of the bosonic integrals has a nature of a central charge, and allows us to liaise the obtained systems with the stationary equations of the Korteweg-de Vries and modified Korteweg-de Vries hierarchies. This exotic supersymmetry o...
Reliability of unstable periodic orbit based control strategies in biological systems
International Nuclear Information System (INIS)
Presence of recurrent and statistically significant unstable periodic orbits (UPOs) in time series obtained from biological systems is now routinely used as evidence for low dimensional chaos. Extracting accurate dynamical information from the detected UPO trajectories is vital for successful control strategies that either aim to stabilize the system near the fixed point or steer the system away from the periodic orbits. A hybrid UPO detection method from return maps that combines topological recurrence criterion, matrix fit algorithm, and stringent criterion for fixed point location gives accurate and statistically significant UPOs even in the presence of significant noise. Geometry of the return map, frequency of UPOs visiting the same trajectory, length of the data set, strength of the noise, and degree of nonstationarity affect the efficacy of the proposed method. Results suggest that establishing determinism from unambiguous UPO detection is often possible in short data sets with significant noise, but derived dynamical properties are rarely accurate and adequate for controlling the dynamics around these UPOs. A repeat chaos control experiment on epileptic hippocampal slices through more stringent control strategy and adaptive UPO tracking is reinterpreted in this context through simulation of similar control experiments on an analogous but stochastic computer model of epileptic brain slices. Reproduction of equivalent results suggests that far more stringent criteria are needed for linking apparent success of control in such experiments with possible determinism in the underlying dynamics
Reliability of unstable periodic orbit based control strategies in biological systems
Mishra, Nagender; Hasse, Maria; Biswal, B.; Singh, Harinder P.
2015-04-01
Presence of recurrent and statistically significant unstable periodic orbits (UPOs) in time series obtained from biological systems is now routinely used as evidence for low dimensional chaos. Extracting accurate dynamical information from the detected UPO trajectories is vital for successful control strategies that either aim to stabilize the system near the fixed point or steer the system away from the periodic orbits. A hybrid UPO detection method from return maps that combines topological recurrence criterion, matrix fit algorithm, and stringent criterion for fixed point location gives accurate and statistically significant UPOs even in the presence of significant noise. Geometry of the return map, frequency of UPOs visiting the same trajectory, length of the data set, strength of the noise, and degree of nonstationarity affect the efficacy of the proposed method. Results suggest that establishing determinism from unambiguous UPO detection is often possible in short data sets with significant noise, but derived dynamical properties are rarely accurate and adequate for controlling the dynamics around these UPOs. A repeat chaos control experiment on epileptic hippocampal slices through more stringent control strategy and adaptive UPO tracking is reinterpreted in this context through simulation of similar control experiments on an analogous but stochastic computer model of epileptic brain slices. Reproduction of equivalent results suggests that far more stringent criteria are needed for linking apparent success of control in such experiments with possible determinism in the underlying dynamics.
Inorganic carbon system dynamics in landfast Arctic sea ice during the early-melt period
Brown, Kristina A.; Miller, Lisa A.; Mundy, C. J.; Papakyriakou, Tim; Francois, Roger; Gosselin, Michel; Carnat, Gauthier; Swystun, Kyle; Tortell, Philippe D.
2015-05-01
We present the results of a 6 week time series of carbonate system and stable isotope measurements investigating the effects of sea ice on air-sea CO2 exchange during the early melt period in the Canadian Arctic Archipelago. Our observations revealed significant changes in sea ice and sackhole brine carbonate system parameters that were associated with increasing temperatures and the buildup of chlorophyll a in bottom ice. The warming sea-ice column could be separated into distinct geochemical zones where biotic and abiotic processes exerted different influences on inorganic carbon and pCO2 distributions. In the bottom ice, biological carbon uptake maintained undersaturated pCO2 conditions throughout the time series, while pCO2 was supersaturated in the upper ice. Low CO2 permeability of the sea ice matrix and snow cover effectively impeded CO2 efflux to the atmosphere, despite a strong pCO2 gradient. Throughout the middle of the ice column, brine pCO2 decreased significantly with time and was tightly controlled by solubility, as sea ice temperature and in situ melt dilution increased. Once the influence of melt dilution was accounted for, both CaCO3 dissolution and seawater mixing were found to contribute alkalinity and dissolved inorganic carbon to brines, with the CaCO3 contribution driving brine pCO2 to values lower than predicted from melt-water dilution alone. This field study reveals a dynamic carbon system within the rapidly warming sea ice, prior to snow melt. We suggest that the early spring period drives the ice column toward pCO2 undersaturation, contributing to a weak atmospheric CO2 sink as the melt period advances.
Multi-Layered Ring Log-Periodic Antennas Array Design for GPS Systems
M. Abri; S.M. Bahloul; H. Abri Badaoui
2012-01-01
The objective of the present study is the design of log periodic ring printed antennas array witch generates circular polarization with wide band by single feed linearly polarized elements for GPS systems. The radiating elements have been fed by magnetic coupling through a slot. The circular polarization is achieved by having a basic 2×2 sub-arrays with unique element angular and phase arrangement, both the element angular orientation and feed phase are arranged in the 0°, 90°, 180 and 270° f...
Chernyak, Vladimir Y; Sinitsyn, Nikolai A
2011-01-01
This article studies Markovian stochastic motion of a particle on a graph with finite number of nodes and periodically time-dependent transition rates that satisfy the detailed balance condition at any time. We show that under general conditions, the currents in the system on average become quantized or fractionally quantized for adiabatic driving at sufficiently low temperature. We develop the quantitative theory of this quantization and interpret it in terms of topological invariants. By implementing the celebrated Kirchhoff theorem we derive a general and explicit formula for the average generated current that plays a role of an efficient tool for treating the current quantization effects.
Buying Time—The Immune System Determinants of the Incubation Period to Respiratory Viruses
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Thomas M. Moran
2010-11-01
Full Text Available Respiratory viruses cause disease in humans characterized by an abrupt onset of symptoms. Studies in humans and animal models have shown that symptoms are not immediate and appear days or even weeks after infection. Since the initial symptoms are a manifestation of virus recognition by elements of the innate immune response, early virus replication must go largely undetected. The interval between infection and the emergence of symptoms is called the incubation period and is widely used as a clinical score. While incubation periods have been described for many virus infections the underlying mechanism for this asymptomatic phase has not been comprehensively documented. Here we review studies of the interaction between human pathogenic respiratory RNA viruses and the host with a particular emphasis on the mechanisms used by viruses to inhibit immunity. We discuss the concept of the “stealth phase”, defined as the time between infection and the earliest detectable inflammatory response. We propose that the “stealth phase” phenomenon is primarily responsible for the suppression of symptoms during the incubation period and results from viral antagonism that inhibits major pathways of the innate immune system allowing an extended time of unhindered virus replication.
Thermodynamics of Micro- and Nano-Systems Driven by Periodic Temperature Variations
Brandner, Kay; Saito, Keiji; Seifert, Udo
2015-07-01
We introduce a general framework for analyzing the thermodynamics of small systems that are driven by both a periodic temperature variation and some external parameter modulating their energy. This setup covers, in particular, periodic micro- and nano-heat engines. In a first step, we show how to express total entropy production by properly identified time-independent affinities and currents without making a linear response assumption. In linear response, kinetic coefficients akin to Onsager coefficients can be identified. Specializing to a Fokker-Planck-type dynamics, we show that these coefficients can be expressed as a sum of an adiabatic contribution and one reminiscent of a Green-Kubo expression that contains deviations from adiabaticity. Furthermore, we show that the generalized kinetic coefficients fulfill an Onsager-Casimir-type symmetry tracing back to microscopic reversibility. This symmetry allows for nonidentical off-diagonal coefficients if the driving protocols are not symmetric under time reversal. We then derive a novel constraint on the kinetic coefficients that is sharper than the second law and provides an efficiency-dependent bound on power. As one consequence, we can prove that the power vanishes at least linearly when approaching Carnot efficiency. We illustrate our general framework by explicitly working out the paradigmatic case of a Brownian heat engine realized by a colloidal particle in a time-dependent harmonic trap subject to a periodic temperature profile. This case study reveals inter alia that our new general bound on power is asymptotically tight.
Heijden, Matthieu van der; Harten, Aart van; Ebben, Mark
2001-01-01
We study vehicle waiting times at a traffic lane that is shared by traffic from two directions. In contrast to crossovers, we focus on instances where the vehicle passing time of the shared infrastructure can be large. The motivation for this model arises from our research on underground transportation systems. We examine vehicle waiting times under periodic control rules, i.e. the driving direction on the infrastructure is switched between two directions according to a fixed time schedule. W...
International Nuclear Information System (INIS)
The classification of closed periodic orbits of convection in a rapidly rotating system is given. It is shown that double torus knots and links, DTK, do occur, which is a very wide and important class of knots and links. We also proved that there is no double torus Lorenz knots, this answers question 6 raised by Hill and Murasugi in [Peter Hill, On double-torus knots 1. J Knot Theor Ramif 1999;8(8):1009-48]. It is also shown that the system produces torus knots and links, for some specific parameters. In fact this approach suggests the study of double torus knots and links through dynamical tools, such as symbolic dynamics and templates
The Education System in East Jerusalem during the Period of Jordanian Rule, 1948-1967
Directory of Open Access Journals (Sweden)
Mustafa Abbasi
2014-01-01
Full Text Available The article below deals with the Arab educational system in East Jerusalem during the period of Jordanian rule, 1948-1967. Its main aim is to examine the attempts and efforts of the Jordanian government promote a new sense of identity among the Palestinians residing in Jerusalem in order to strengthen their loyalty to the Hashemite regime that had annexed the West Bank and turned it into an inseparable part of the Kingdom of Jordan. The article shows how the educational system was inducted for the purpose of constructing this new identity through a comprehensive change in study programs and textbooks. However, in spite of this, these efforts failed and Palestinian identity was preserved and even strengthened.
Non-linear second-order periodic systems with non-smooth potential
Papageorgiou, E H; Papageorgiou, Evgenia H; Papageorgiou, Nikolaos S
2005-01-01
In this paper we study second order non-linear periodic systems driven by the ordinary vector $p$-Laplacian with a non-smooth, locally Lipschitz potential function. Our approach is variational and it is based on the non-smooth critical point theory. We prove existence and multiplicity results under general growth conditions on the potential function. Then we establish the existence of non-trivial homoclinic (to zero) solutions. Our theorem appears to be the first such result (even for smooth problems) for systems monitored by the $p$-Laplacian. In the last section of the paper we examine the scalar \\hbox{non-linear} and semilinear problem. Our approach uses a generalized Landesman--Lazer type condition which generalizes previous ones used in the literature. Also for the semilinear case the problem is at resonance at any eigenvalue.
International Nuclear Information System (INIS)
This paper is devoted to the numerical computation and continuation of families of heteroclinic connections between hyperbolic periodic orbits (POs) of a Hamiltonian system. We describe a method that requires the numerical continuation of a nonlinear system that involves the initial conditions of the two POs, the linear approximations of the corresponding manifolds and a point in a given Poincaré section where the unstable and stable manifolds match. The method is applied to compute families of heteroclinic orbits between planar Lyapunov POs around the collinear equilibrium points of the restricted three-body problem in different scenarios. In one of them, for the Sun–Jupiter mass parameter, we provide energy ranges for which the transition between different resonances is possible. (paper)
Quasi-periodic motions in families of dynamical systems order amidst chaos
Broer, Hendrik W; Sevryuk, Mikhail B
1996-01-01
This book is on Kolmogorov-Arnol'd-Moser theory for quasi-periodic tori in dynamical systems. It gives an up-to-date report on the role parameters play for persis- tence of such tori, typically occuring on Cantor sets of positive Hausdorff measure inside phase and parameter space. The cases with preservation of symplectic or volume forms or time-reversal symmetries are included. The concepts of Whitney-smoothness and Diophantine approximation of Cantor sets on submanifolds of Euclidean space are treated, as well as Bruno's theory on analytic continuation of tori. Partly this material is new to Western mathematicians. The reader should be familiar with dynamical systems theory, differen- tial equations and some analysis. The book is directed to researchers, but its entrance level is introductory.
Barrabés, E.; Mondelo, J. M.; Ollé, M.
2013-10-01
This paper is devoted to the numerical computation and continuation of families of heteroclinic connections between hyperbolic periodic orbits (POs) of a Hamiltonian system. We describe a method that requires the numerical continuation of a nonlinear system that involves the initial conditions of the two POs, the linear approximations of the corresponding manifolds and a point in a given Poincaré section where the unstable and stable manifolds match. The method is applied to compute families of heteroclinic orbits between planar Lyapunov POs around the collinear equilibrium points of the restricted three-body problem in different scenarios. In one of them, for the Sun-Jupiter mass parameter, we provide energy ranges for which the transition between different resonances is possible.
Directory of Open Access Journals (Sweden)
A. P. Shete
2013-03-01
Full Text Available Experiment with varied water circulation periods having 4, 8, 12, and 24 hrs/day as T1, T2, T3 and T4, respectively in aquaponics, evaluated against a control (without aquaponics revealed higher fish and plant growth in T3 and T4. The mean growth of fish varied significantly among treatments showing higher growth in T4 and control followed by T3, T2 and T1. Survival rate was 100% in all the treatments as well as control. Percentage weight gain, SGR (% day-1 also showed the similar trend as that of growth showing T4 as better treatment immediately followed by T3 then T2 and T1. The system maintained favourable water quality throughout the experiment. The growth in T3 and T4 did not vary significantly and was higher than the T1, T2 and control. Also percentage length gain at the end of the trial was maximum in T3 and T4. The Chl (a+b content in the control was higher than all the treatments whereas, T4 showed the maximum concentration among treatments followed by T3, T2 and then T1. Comparison of all the growth attributes and water quality parameters indicated that water circulation can be reduced to 12 hrs/day for economically effective aquaponics and can be considered as optimum water circulation period for goldfish production in aquaponic system.
The ground state of binary systems with a periodic modulation of the linear coupling
Niederberger, Armand; Lewenstein, Maciej
2010-01-01
We consider a quasi-one-dimensional two-component systm, described by a pair of Nonlinear Schr\\"{o}dinger/Gross-Pitaevskii Equations (NLSEs/GPEs), which are coupled by the linear mixing, with local strength $\\Omega $, and by the nonlinear incoherent interaction. We assume the self-repulsive nonlinearity in both components, and include effects of a harmonic trapping potential. The model may be realized in terms of periodically modulated slab waveguides in nonlinear optics, and in Bose-Einstein condensates too. Depending on the strengths of the linear and nonlinear couplings between the components, the ground states (GSs) in such binary systems may be symmetric or asymmetric. In this work, we introduce a periodic spatial modulation of the linear coupling, making $\\Omega $ an odd, or even function of the coordinate. The sign flips of $\\Omega (x)$ strongly modify the structure of the GS in the binary system, as the relative sign of its components tends to lock to the local sign of $\\Omega $. Using a systematic nu...
Raupach, Marc; Tonner, Ralf
2015-05-21
The development and first applications of a new periodic energy decomposition analysis (pEDA) scheme for extended systems based on the Kohn-Sham approach to density functional theory are described. The pEDA decomposes the bonding energy between two fragments (e.g., the adsorption energy of a molecule on a surface) into several well-defined terms: preparation, electrostatic, Pauli repulsion, and orbital relaxation energies. This is complemented by consideration of dispersion interactions via a pairwise scheme. One major extension toward a previous implementation [Philipsen and Baerends, J. Phys. Chem. B 110, 12470 (2006)] lies in the separate discussion of electrostatic and Pauli and the addition of a dispersion term. The pEDA presented here for an implementation based on atomic orbitals can handle restricted and unrestricted fragments for 0D to 3D systems considering periodic boundary conditions with and without the determination of fragment occupations. For the latter case, reciprocal space sampling is enabled. The new method gives comparable results to established schemes for molecular systems and shows good convergence with respect to the basis set (TZ2P), the integration accuracy, and k-space sampling. Four typical bonding scenarios for surface-adsorbate complexes were chosen to highlight the performance of the method representing insulating (CO on MgO(001)), metallic (H2 on M(001), M = Pd, Cu), and semiconducting (CO and C2H2 on Si(001)) substrates. These examples cover diverse substrates as well as bonding scenarios ranging from weakly interacting to covalent (shared electron and donor acceptor) bonding. The results presented lend confidence that the pEDA will be a powerful tool for the analysis of surface-adsorbate bonding in the future, enabling the transfer of concepts like ionic and covalent bonding, donor-acceptor interaction, steric repulsion, and others to extended systems. PMID:26001445
Predicting the onset of period-doubling bifurcations in noisy cardiac systems.
Quail, Thomas; Shrier, Alvin; Glass, Leon
2015-07-28
Biological, physical, and social systems often display qualitative changes in dynamics. Developing early warning signals to predict the onset of these transitions is an important goal. The current work is motivated by transitions of cardiac rhythms, where the appearance of alternating features in the timing of cardiac events is often a precursor to the initiation of serious cardiac arrhythmias. We treat embryonic chick cardiac cells with a potassium channel blocker, which leads to the initiation of alternating rhythms. We associate this transition with a mathematical instability, called a period-doubling bifurcation, in a model of the cardiac cells. Period-doubling bifurcations have been linked to the onset of abnormal alternating cardiac rhythms, which have been implicated in cardiac arrhythmias such as T-wave alternans and various tachycardias. Theory predicts that in the neighborhood of the transition, the system's dynamics slow down, leading to noise amplification and the manifestation of oscillations in the autocorrelation function. Examining the aggregates' interbeat intervals, we observe the oscillations in the autocorrelation function and noise amplification preceding the bifurcation. We analyze plots-termed return maps-that relate the current interbeat interval with the following interbeat interval. Based on these plots, we develop a quantitative measure using the slope of the return map to assess how close the system is to the bifurcation. Furthermore, the slope of the return map and the lag-1 autocorrelation coefficient are equal. Our results suggest that the slope and the lag-1 autocorrelation coefficient represent quantitative measures to predict the onset of abnormal alternating cardiac rhythms. PMID:26170301
Optimal dispatching in a periodically review in on-line manufacturing system with vendors evaluation
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Dipak Ranjan Jana
2011-04-01
Full Text Available This paper, we consider dynamic dispatching control of a fully flexible online manufacturing system. Hence, vendors, who supply the materials, play an important role in this system. So, selection of vendors is much important. In a periodically reviewed, online manufacturing system where materials are dispatched from a central control station to different manufacturing sales. After production process, the parts are routed to inspection and quality control room. Hence optimal dispatching policies are pursued to minimize the in-process inventory carrying / holding cost over finite horizon. A dynamic programming formulation is developed for optimal dispatching which shows that the dynamic recursive functions (i.e. cost – to go – function are convex and monotonic under the condition of low defects rates and relative low cost material handling. From the derivation we conclude that optimal dispatching sales for a combination of zero inventory and Non- zero inventory policies. Thus, the optimal input control is proved to be in the form a pulling system.
Chemical effects of (n,2n) reactions on iodate and periodates systems
International Nuclear Information System (INIS)
The chemical consequences of (n,2n) reactions on cristalline sodium iodate and periodates were investigated measuring the initial yield and the post irradiation thermal annealing yields (900C) of the separated fractions I-, IO3- and IO4-. NaIO3, NaIO3.H2O and NaIO4, Na4H2IO6, Na4I2O9.3H2O containing 127I and 129I, or both, were irradiated with 14 MeV neutrons. Results obtained show different effects for each system and that 126I and 128I isotopes keep the same behaviour in the irradiated compounds containing only ?127I or 129I and in compounds having both 127I and 129I. Neither isotope effect nor qualitative differences on thermal annealing at 900C were observed. The annealed fractions in the three studied periodates were IO-3 and IO-4. These results differ from the ones reported previously for (n,?) reactions on the same compounds
International Nuclear Information System (INIS)
It has been shown that in reality at least two general scenarios of data structuring are possible: (a) a self-similar (SS) scenario when the measured data form an SS structure and (b) a quasi-periodic (QP) scenario when the repeated (strongly correlated) data form random sequences that are almost periodic with respect to each other. In the second case it becomes possible to describe their behavior and express a part of their randomness quantitatively in terms of the deterministic amplitude–frequency response belonging to the generalized Prony spectrum. This possibility allows us to re-examine the conventional concept of measurements and opens a new way for the description of a wide set of different data. In particular, it concerns different complex systems when the ‘best-fit’ model pretending to be the description of the data measured is absent but the barest necessity of description of these data in terms of the reduced number of quantitative parameters exists. The possibilities of the proposed approach and detection algorithm of the QP processes were demonstrated on actual data: spectroscopic data recorded for pure water and acoustic data for a test hole. The suggested methodology allows revising the accepted classification of different incommensurable and self-affine spatial structures and finding accurate interpretation of the generalized Prony spectroscopy that includes the Fourier spectroscopy as a partial case. (paper)
IP Eri: A surprising long-period binary system hosting a He white dwarf
Merle, T; Masseron, T; Van Eck, S; Siess, L; Van Winckel, H
2014-01-01
We determine the orbital elements for the K0 IV + white dwarf (WD) system IP Eri, which appears to have a surprisingly long period of 1071 d and a significant eccentricity of 0.25. Previous spectroscopic analyses of the WD, based on a distance of 101 pc inferred from its Hipparcos parallax, yielded a mass of only 0.43 M$_\\odot$, implying it to be a helium-core WD. The orbital properties of IP Eri are similar to those of the newly discovered long-period subdwarf B star (sdB) binaries, which involve stars with He-burning cores surrounded by extremely thin H envelopes, and are therefore close relatives to He WDs. We performed a spectroscopic analysis of high-resolution spectra from the HERMES/Mercator spectrograph and concluded that the atmospheric parameters of the K0 component are $T_{\\rm eff} = 4960$ K, $\\log{g} = 3.3$, [Fe/H] = 0.09 and $\\xi = 1.5$ km/s. The detailed abundance analysis focuses on C, N, O abundances, carbon isotopic ratio, light (Na, Mg, Al, Si, Ca, Ti) and s-process (Sr, Y, Zr, Ba, La, Ce, N...
Dietel, J; Hekking, F; Von Oppen, F
2004-01-01
Motivated by the recently discovered microwave-induced ``zero-resistance'' states in two-dimensional electron systems, we study the microwave photoconductivity of a two-dimensional electron gas (2DEG) subject to a unidirectional static periodic potential. The combination of this potential, the classically strong magnetic field, and the microwave radiation may result in an anisotropic negative conductivity of the 2DEG. Similar to the case of a smooth random potential, two mechanisms contribute to the negative photoconductivity. The displacement mechanism arises from electron transitions due to disorder-assisted microwave absorption and emission. The distribution-function mechanism arises from microwave-induced changes in the electron distribution. However, the replacement of a smooth random potential by the unidirectional one, leads to different relative strengths of the two contributions to the photoconductivity. The distribution function mechanism dominates the photoconductivity in the direction of the stati...
Discharge formation systems for generating atomic iodine in a pulse-periodic oxygen-iodine laser
Aksinin, V. I.; Antsiferov, S. A.; Velikanov, S. D.; Gerasimov, A. Yu; Gostev, I. V.; Kazantsev, S. Yu; Kalinovskii, V. V.; Konovalov, V. V.; Kononov, I. G.; Mikhalkin, V. N.; Podlesnykh, S. V.; Sevryugin, I. V.; Firsov, K. N.
2014-01-01
Generation characteristics of a pulse-periodic oxygen-iodine laser with the electro-discharge production of atomic iodine were compared with inductively stabilised edged or anisotropic- resistive cathodes used for ignition of the volume discharge. The discharge was initiated by the radiation of a barrier discharge from the side of a grid anode. It was found that at equal specific electrical energy depositions to the gas-discharge plasma, the system with the anisotropic-resistive cathode provides a more stable and uniform volume discharge with the possibility of varying the composition and pressure of working mixtures over a wide range and a greater specific extraction of laser energy is observed (up to 2.4 J L-1). At a high pulse repetition rate of laser pulses (50 - 100 Hz) and long duration of the pulse trains (longer than a minute) the surface of anisotropic-resistive cathode became eroded.
Spin Waves in a Ferromagnetic Film with a Periodic System of Antidots
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V.V. Kulish
2015-03-01
Full Text Available In the paper, spin waves in a thin film (composed of a uniaxial ferromagnet with a two-dimensional periodical system of antidots are studied. The film ferromagnet is considered to have the “easy axis” type. To describe such waves, the magnetostatic approximation with account for the magnetic dipole-dipole interaction, the exchange interaction and the anisotropy effects is used. For such waves, an equation for the magnetic potential is derived; for the case of remote antidots, the dispersion relation and the transverse wavenumber spectrum are found. For the case of a film thin compared to the exchange length and for the case of a film bounded by a high-conductivity metal, the longitudinal wavenumber spectrum and the frequency spectrum of such spin waves are also obtained.
[The health and epidemic prevention system of Qingdao in German occupation period].
Jin, Xia
2012-07-01
In 1893, the German army occupied Qingdao and the 17-year-long control began. During the occupation period, the German colonial government had taken a series of health and epidemic prevention measures, including solving the drinking water problem, improving living conditions, sewer construction, and sewage and garbage disposal to promote the level of sanitation. They also established epidemic prevention and treatment institutions, including epidemic administration and reporting. A series of rules for epidemic prevention were put forward and executed by police officers. Those measures played a role in the administration, legalization and professionalization of the health and epidemic prevention system in Qingdao and initiated the preliminary modern transformation of the health prevention mechanism. PMID:23336277
The optimal P3M algorithm for computing electrostatic energies in periodic systems
Ballenegger, V; Holm, Ch; Lenz, O
2007-01-01
We optimize Hockney and Eastwood's Particle-Particle Particle-Mesh (P3M) algorithm to achieve maximal accuracy in the electrostatic energies (instead of forces) in 3D periodic charged systems. To this end we construct an optimal influence function that minimizes the RMS errors in the energies. As a by-product we derive a new real-space cut-off correction term, give a transparent derivation of the systematic errors in terms of Madelung energies, and provide an accurate analytical estimate for the RMS error of the energies. This error estimate is a useful indicator of the accuracy of the computed energies, and allows an easy and precise determination of the optimal values of the various parameters in the algorithm (Ewald splitting parameter, mesh size and charge assignment order).
Periodic and chaotic oscillations in a tumor and immune system interaction model with three delays
Energy Technology Data Exchange (ETDEWEB)
Bi, Ping [Department of Mathematics, Shanghai Key Laboratory of PMMP, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Center for Partial Differential Equations, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Ruan, Shigui, E-mail: ruan@math.miami.edu [Department of Mathematics, University of Miami, Coral Gables, Florida 33124-4250 (United States); Zhang, Xinan [School of Mathematics and Statistics, Central China Normal University, Wuhan 430079 (China)
2014-06-15
In this paper, a tumor and immune system interaction model consisted of two differential equations with three time delays is considered in which the delays describe the proliferation of tumor cells, the process of effector cells growth stimulated by tumor cells, and the differentiation of immune effector cells, respectively. Conditions for the asymptotic stability of equilibria and existence of Hopf bifurcations are obtained by analyzing the roots of a second degree exponential polynomial characteristic equation with delay dependent coefficients. It is shown that the positive equilibrium is asymptotically stable if all three delays are less than their corresponding critical values and Hopf bifurcations occur if any one of these delays passes through its critical value. Numerical simulations are carried out to illustrate the rich dynamical behavior of the model with different delay values including the existence of regular and irregular long periodic oscillations.
Scientific Electronic Library Online (English)
G. M., Ramírez Ávila; J. A., C. Gallas.
Full Text Available Se caracterizan diferentes sistemas dinámicos descritos por mapas mediante el cálculo de periodicidades. Este método es alternativo a los diagramas de bifurcación utilizando los exponentes de Lyapunov ya que no sólo permite visualizar las estructuras existentes en el espacio de parámetros, tales com [...] o los "camarones", sino también proporciona el detalle de los regímenes oscilatorios lo cual puede tener importancia desde el punto de vista práctico. Abstract in english We characterize, by means of periodicities, some dynamical systems represented by maps. This is an alternative method to the common bifurcation diagrams computed by using the Lyapunov exponents and allows us to visualize the typical structures onto the parameter space such as the "shrimps" but in ad [...] dition with the detail of the oscillatory regimes which could be important from a practical viewpoint.
Quantum effects on Lagrangian points and displaced periodic orbits in the Earth-Moon system
Battista, Emmanuele; Dell'Agnello, Simone; Esposito, Giampiero; Simo, Jules
2015-04-01
Recent work in the literature has shown that the one-loop long distance quantum corrections to the Newtonian potential imply tiny but observable effects in the restricted three-body problem of celestial mechanics; i.e., at the Lagrangian libration points of stable equilibrium, the planetoid is not exactly at an equal distance from the two bodies of large mass, but the Newtonian values of its coordinates are changed by a few millimeters in the Earth-Moon system. First, we assess such a theoretical calculation by exploiting the full theory of the quintic equation, i.e., its reduction to Bring-Jerrard form and the resulting expression of roots in terms of generalized hypergeometric functions. By performing the numerical analysis of the exact formulas for the roots, we confirm and slightly improve the theoretical evaluation of quantum corrected coordinates of Lagrangian libration points of stable equilibrium. Second, we prove in detail that for collinear Lagrangian points the quantum corrections are also of the same order of magnitude in the Earth-Moon system. Third, we discuss the prospects of measuring, with the help of laser ranging, the above departure from the equilateral triangle picture, which is a challenging task. On the other hand, a modern version of the planetoid is the solar sail, and much progress has been made, in recent years, on the displaced periodic orbits of solar sails at all libration points, both stable and unstable. Therefore, the present paper investigates, eventually, a restricted three-body problem involving Earth, the Moon, and a solar sail. By taking into account the one-loop quantum corrections to the Newtonian potential, displaced periodic orbits of the solar sail at libration points are again found to exist.
Assessment of the expected number and frequency of failures of periodically tested systems
International Nuclear Information System (INIS)
The safety and reliability analysis of any system necessarily requires first to model its behavior or its failure logic, and second to assess its performance by using the previously chosen model. Among these performance indicators there is the failure frequency. In spite of its interest, it is not very often used, except in the standards devoted to the so-called functional safety, in which its genuine nature is not always made explicit. A sound method dedicated to the modeling and computing of the failure frequency of periodically tested systems is proposed in this paper. This type of systems comprises components with an availability curve which is discontinuous at deterministic instants. These discontinuities induce, in turn and at the same instants, frequency discontinuities. The impact of the latter on the overall value of the failure frequency is important, but largely unknown and therefore not taken into account in the safety and reliability area, in spite of the fact that it generally induces optimistic estimation, if no compensatory action is planned. The presented method is based on the notion of “critical state” and the use of advanced fault tree models (FT). The results obtained from these models are checked by using Monte Carlo simulation technique supported by equivalent Petri nets models (PN)
Range-separated double-hybrid density-functional theory applied to periodic systems
Sansone, Giuseppe; Usvyat, Denis; Toulouse, Julien; Sharkas, Kamal; Maschio, Lorenzo
2015-01-01
Quantum chemistry methods exploiting density-functional approximations for short-range electron-electron interactions and second-order M{{\\o}}ller-Plesset (MP2) perturbation theory for long-range electron-electron interactions have been implemented for periodic systems using Gaussian-type basis functions and the local correlation framework. The performance of these range-separated double hybrids has been benchmarked on a significant set of systems including rare-gas, molecular, ionic, and covalent crystals. The use of spin-component-scaled MP2 for the long-range part has been tested as well. The results show that the value of $\\mu$ = 0.5 bohr^{--1} for the range-separation parameter usually used for molecular systems is also a reasonable choice for solids. Overall, these range-separated double hybrids provide a good accuracy for binding energies using basis sets of moderate sizes such as cc-pVDZ and aug-cc-pVDZ.
Directory of Open Access Journals (Sweden)
Jiwei He
2007-07-01
Full Text Available In this paper, we consider a nonautonomous multispecies competition predator-prey system with Holling's type III functional response and prey supplement. It is proved that the system is uniformly persistent under some conditions. Furthermore, we show that the system has a unique positive periodic solution which is globally asymptotically stable.
International Nuclear Information System (INIS)
In this paper, we investigate the dynamic behaviors of a two-prey two-predator system with impulsive effect concerning biological and chemical control strategy-periodic releasing natural enemies and spraying pesticide at different fixed time. By applying the Floquet theory of linear periodic impulsive equation and small amplitude perturbation method, we prove that there exists a globally asymptotically stable two-prey-eradication periodic solution when the impulsive period is less than some critical value. The conditions for the permanence of the system are given, and meanwhile the conditions for the extinction of one of the two prey species and permanence of the remaining three species are given. Our results suggest a new approach in pest control. The target pest population can be driven to extinction and the non-target pest can be permanent by choosing impulsive period. With the increasing of the predation rate for the super competitor and impulsive period, the system displays complicated behaviors including a sequence of direct and inverse cascades of periodic-doubling, periodic-halfing, chaos, and symmetry breaking bifurcation
Investigation of periodic systems by means of the generalized Hill method
International Nuclear Information System (INIS)
We propose the new method of investigation of infinite periodic determination which is a generalized Hill method. This method has been used for finding of the characteristic value for the Hill equation. finding the band structure of the one-dimensional periodic and obtaining of the dispersion equation for the electromagnetic wave propagation in the waveguide by plasma arbitrary periodic density modulation by plasma arbitrary periodic density modulation
Directory of Open Access Journals (Sweden)
YANG Zhi-chun
2010-09-01
Full Text Available Based on the previous studies of functional reaction Holling limited predator-prey system, this paper expands Limited class to N and discusses the permanence and existence of periodic solution for predator-prey system with Holling-N type functional response. Firstly, a discrete model of the systemis formulated.Then ,by the skills of inequalities,we obtain a sufficient condition ensuring the permanence for predator-prey system.*, where *. Under the assumption of *, based on the results ,the existence of periodic solution of system is derived by using Brouwer fixed point theory.(* Indicates a formula, please see the full text
Rigo, Tomeu; Llasat, Maria-Carmen
2007-02-01
The aim of this paper is to show a climatology of Mesoscale Convective Systems (MCS) in the NE of the Iberian Peninsula, on the basis of meteorological radar observations. Special attention was paid to those cases that have produced heavy rainfalls during the period 1996-2000. Identification of the MCS was undertaken using two procedures. Firstly, the precipitation structures at the lowest level were recognised by means of a 2D algorithm that distinguishes between convective and non-convective contribution. Secondly, the convective cells were identified using a 3D procedure quite similar to the SCIT (Storm Cell Identification and Tracking) algorithm that looks for the reflectivity cores in each radar volume. Finally, the convective cells (3D) were associated with the 2D structures (convective rainfall areas), in order to characterize the complete MCS. Once this methodology was presented the paper offers a proposal for classifying the precipitation systems, and particularly the MCS. 57 MCS structures were classified: 49% of them were identified as linearly well-organised systems, called TS (39%), LS (18%) and NS (43%). In addition to the classification, the following items were analysed for each MCS found: duration, season, time of day, area affected and direction of movement, and main radar parameters related with convection. The average features of those MCS show an area of about 25000 km 2, Zmax values of 47 dBz, an echotop of 12 km, the maximum frequency at 12 UTC and early afternoon and a displacement towards E-NE. The study was completed by analysing the field at surface, the presence of a mesoscale low near the system and the quasi-stationary features of three cases related with heavy rainfalls. Maximum rainfall (more then 200 mm in 6 h) was related with the presence of a cyclone in combination with the production of a convective train effect.
Hambleton, K M; Prsa, A; Guzik, J A; Pavlovski, K; Bloemen, S; Southworth, J; Conroy, K; Littlefair, S P; Fuller, J
2013-01-01
We present Kepler photometry and ground based spectroscopy of KIC 4544587, a short-period eccentric eclipsing binary system with self-excited pressure and gravity modes, tidally excited modes, tidally influenced p modes, and rapid apsidal motion of 182 y per cycle. The primary and secondary components of KIC 4544587 reside within the delta Scuti and gamma Dor instability region of the Hurtzsprung-Russell diagram, respectively. By applying the binary modelling software PHOEBE to prewhitened Kepler photometric data and radial velocity data obtained using the William Herschel Telescope and 4-m Mayall telescope at KPNO, the fundamental parameters of this important system have been determined, including the stellar masses, 1.98+/-0.07 MSun and 1.60+/-0.06 MSun, and radii, 1.76+/-0.03 RSun and 1.42+/-0.02 RSun, for the primary and secondary components, respectively. Frequency analysis of the residual data revealed 31 modes, 14 in the gravity mode region and 17 in the pressure mode region. Of the 14 gravity modes 8 ...
New dimensions of the periodic system: superheavy, superneutronic, superstrange, antimatter nuclei
Greiner, Walter
2010-12-01
The possibilities for the extension of the periodic system into the islands of superheavy (SH) elements, to and beyond the neutron drip line and to the sectors of strangeness and antimatter are discussed. The multi-nucleon transfer processes in low-energy damped collisions of heavy actinide nuclei may help us to fill the gap between the nuclei produced in the "hot" fusion reactions and the continent of known nuclei. In these reactions we may also investigate the "island of stability". In many such collisions the lifetime of the composite giant system consisting of two touching nuclei turns out to be rather long (?10-20 s); sufficient for observing line structure in spontaneous positron emission from super-strong electric fields (vacuum decay), a fundamental QED process not observed yet experimentally. At the neutron-rich sector near the drip line islands and extended ridges of quasistable nuclei are predicted by HF calculations. Such nuclei, as well as very long living superheavy nuclei may be provided in double atomic bomb explosions. A tremendously rich scenario of new nuclear structure emerges with new magic numbers in the strangeness domain. Various production mechanisms are discussed for these objects and for antinuclei in high energy heavy-ion collisions.
Analysis of the ancient river system in Loulan period in Lop Nur region
Zhu, Jianfeng; Jia, Peng; Nie, Yueping
2010-09-01
The Lop Nur region is located in the east of the Tarim Basin. It has served as the strategic passage and communication hub of the Silk Road since Han Dynasty. During Wei-Jin period, the river system there was well developed and the ancient city of Loulan was bred there. In this study, GIS is used to accomplish automatic extraction of the river course in the Lop Nur region at first using ArcGIS. Then the RCI index is constituted to extract ancient river course from Landsat ETM image with band 3 and band 4. It is concluded that the north river course of Peacock River conformed before the end of the 4th century AD according to the distribution of the entire river course of the Lop Nur region. Later, the Peacock River changed its way to south to Tarim River, and flowed into Lop Nur along the direction paralleling Altun Mountain from west to east. It was the change of the river system that mainly caused the decrease in water supply around ancient city of Loulan before the end of 4th century. The ancient city of Loulan has been gradually ruined in the sand because of the absence of water supply since then.
PHYSICAL PROPERTIES OF THE 0.94-DAY PERIOD TRANSITING PLANETARY SYSTEM WASP-18
International Nuclear Information System (INIS)
We present high-precision photometry of five consecutive transits of WASP-18, an extrasolar planetary system with one of the shortest orbital periods known. Through the use of telescope defocusing we achieve a photometric precision of 0.47-0.83 mmag per observation over complete transit events. The data are analyzed using the JKTEBOP code and three different sets of stellar evolutionary models. We find the mass and radius of the planet to be M b = 10.43 ± 0.30 ± 0.24 M Jup and R b = 1.165 ± 0.055 ± 0.014 R Jup (statistical and systematic errors), respectively. The systematic errors in the orbital separation and the stellar and planetary masses, arising from the use of theoretical predictions, are of a similar size to the statistical errors and set a limit on our understanding of the WASP-18 system. We point out that seven of the nine known massive transiting planets (M b > 3 M Jup) have eccentric orbits, whereas significant orbital eccentricity has been detected for only four of the 46 less-massive planets. This may indicate that there are two different populations of transiting planets, but could also be explained by observational biases. Further radial velocity observations of low-mass planets will make it possible to choose between these two scenarios.
Marrocu, M.; Chessa, P. A.
2003-04-01
The multi-model/multi-analysis technique to build ensemble forecasts has recently been applied to General Circulation Models both for Weather and Seasonal predictions. The application to regional models is seen as a natural extension of this technique, but a thoroughly study on its feasibility is not as yet available. Among the points to be carefully addressed is how to set the so called training period needed to assess the weights to be used for the blending of the different forecasts of the ensemble. For this reason, in the way of set up an operational mesoscale multi-model/multi-analysis ensemble system (MuSE), a preliminary assessment has been accomplished of a few methods devoted to find the ensemble weights. The study has been carried out using a simplified multi-analysis system composed of lagged forecasts verifying at the same time. The related ensembles have been built using two different sets of weights, obtained through a multi-linear regression and a kalman filter. A preliminary comparison of the results obtained using these two methods will be discussed.
Short-period low-mass binary system CC Com revisited
Kose, O; Keskin, V; Ulas, B; Yakut, K
2011-01-01
In this study we determined precise orbital and physical parameters of the very short period low-mass contact binary system CC Com. The parameters are obtained by analysis of the new CCD data with the archival spectroscopic data. The physical parameters of the components derived as $M_\\textrm{c}$ = 0.717(14) $M_{\\odot}$, $M_\\textrm{h}$ = 0.378(8) $M_{\\odot}$, $R_\\textrm{c}$ = 0.708(12) $R_{\\odot}$, $R_\\textrm{h}$ = 0.530(10) $R_{\\odot}$, $L_\\textrm{c}$ = 0.138(12) $L_{\\odot}$, $L_\\textrm{h}$ = 0.085(7) $L_{\\odot}$, and the distance of the system is estimated as 64(4) pc. The times of minima obtained in this study and with those published before enable us to calculate the mass transfer rate between the components which is $1.6\\times10^{-8}$ M$_{\\odot}$yr$^{-1}$. Finally, we discuss the possible evolutionary scenario of CC Com.
Alan, Emel; Liman, Narin; Sa?söz, Hakan
2015-06-01
The epidermal growth factor (EGF) plays a crucial role in the control of uterine cell proliferation, growth and differentiation. This study was designed to investigate the spatiotemporal expression pattern and localization of the EGF receptor/ligand system during the process of uterine involution using immunohistochemistry. Our results indicated that the expression of the ErbB/HER receptors and their ligands varied with structural changes in the uterus at different days of involution. Supranuclear punctate ErbB1 immunostaining was observed in the luminal and glandular epithelial cells and endometrial fibroblasts. Moderate ErbB2/HER2 immunoreactivity was observed in the lateral membrane and cytoplasm of the epithelial cells on the 1st, 3rd and 5th days and was decreased on the other days of involution. The amount of nuclear and cytoplasmic ErbB3/HER3 and ErbB4/HER4 immunostaining remained constant throughout the postpartum period. The EGF immunoreaction was weak in the luminal and glandular epithelium throughout the involution period. Although the cytoplasmic AREG immunoreactivity in the glandular epithelium was stronger on the 1st and 3rd days compared with the other days of involution, NRG1 immunostaining was weak on the 1st and 3rd days and was moderate in the apical cytoplasm on the 10th and 15th days of involution. The macrophages displayed strong cytoplasmic immunoreactivity for ErbB3/HER3, ErbB4/HER4, EGF, AREG and NRG. Strong, moderate and weak immunostaining for ErbB2/HER2, ErbB4/HER4 and other proteins (ErbB1, ErbB3, AREG and NRG), respectively, was present in the myometrial smooth muscle cells. These findings support the hypothesis that the EGFsystem plays a role in the development of various physiological changes associated with uterine involution. PMID:25754972
The Dynamics of known Short-period Multi-planet Systems in the Presence of Outer Planets
Granados Contreras, Agueda P.; Boley, Aaron C.
2014-11-01
Among the Kepler planet candidate sample, 23% of stellar hosts contain multiple transiting planet candidates (Burke et al. 2014). The false positive rate among the multi-candidate systems is expected to be very low, suggesting that the candidates in these systems are truly planets. The large abundance of these systems suggests that the formation of multi-planet systems at short orbital periods (the candidate period distribution peaks between 10 and 20 days) is a fundamental mode of planet formation. However, we do not understand what processes lead to the diversity of planetary systems or whether the formation processes that give rise to Kepler multi-planet systems also permit the formation of distant planets akin to the Solar System. To this end, we explore the consequences that outer planets have on the stability and observability of known Kepler and Kepler-like multi-planet systems.
Tamagawa, H; Ojima, M; Tanaka, M; Shizukuishi, S
1995-01-01
In this paper, we evaluate the efficiency of our multi-user system, which enables undergraduate students to now determine their progress in clinical requirements through their clinical training period. After implementing the system, instructors in each clinic can understand the progress or laziness of every student better than before. PMID:8591434
Exact solution for quantum dynamics of a periodically-driven two-level-system
Gangopadhyay, Anirban; Galitski, Victor
2010-01-01
We present a family of exact analytic solutions for non-linear quantum dynamics of a two-level system (TLS) subject to a periodic-in-time external field. In constructing the exactly solvable models, we use a "reverse engineering" approach where the form of external perturbation is chosen to preserve an integrability constraint, which yields a single non-linear differential equation for the ac-field. A solution to this equation is expressed in terms of Jacobi elliptic functions with three independent parameters that allows one to choose the frequency, average value, and amplitude of the time-dependent field at will. This form of the ac-drive is especially relevant to the problem of dynamics of TLS charge defects that cause dielectric losses in superconducting qubits. We apply our exact results to analyze non-linear dielectric response of such TLSs and show that the position of the resonance peak in the spectrum of the relevant correlation function is determined by the quantum-mechanical phase accumulated by th...
Directory of Open Access Journals (Sweden)
Afsin Kundak
2014-01-01
Full Text Available In the neonatal period, upper gastrointestinal system (GIS bleeding may be due to benign disorders which do not require any treatments or may be relevant to serious conditions requiring urgent intervention. There are two major causes of upper GIS bleeding developed in the newborns; vitamin K deficiency-induced hemorrhagic disease of the newborn and maternal blood swallowed during birth. Other causes of this type of bleeding include gastritis, esophagitis, peptic ulcus (PU, coagulopathy, sepsis, vascular malformations, trauma, and esofageal-gastric duplications. Rarely, gastric erosion or perforation due to oro/naso gastric tube might cause severe upper GIS bleeding. Hemodynamic resuscitation, bleeding control, and prevention of the recurrence form the basis of the management. However, a somatostatin analogue (ocreotide may be helpful by reducing the splanchnic blood if bleeding is caused by a known vascular lesion or arterial erosion. In this paper, a case of newborn with upper GIS bleeding developed within the first 24 hour life and probably caused by arterial erosion due to oro/gastric tube and treated by ocreotide was presented in the light of literature.
A Periodical Production Plan for Uncertain Orders in a Closed-Loop Supply Chain System
Directory of Open Access Journals (Sweden)
Hsiao-Fan Wang
2014-12-01
Full Text Available Production planning is a major activity in the manufacturing or processing industries. A good plan helps the company lower its expenses, increase profit, or both. However, the worldwide economy is made up of closely related systems. Thus, a small change induces fluctuation in the supply chain. Although a production plan is based on the predicted demand, economic fluctuations make prediction difficult. Therefore, coping with production risksof uncertain demands heavily depends on the judgment and experience of the producer or customer. In addition, the reuse of recyclable products has become a major approach in reducing resource consumption because of environmental consciousness. Thus, a closed-loop supply chain has replaced the traditional supply chain to facilitate recycling, accommodate reprocess, ease environmental degradation, and save on resource costs. This study thus considers a production plan in a closed-loop supply chain, where periodic orders of retailers are adjusted and described byfuzzy quantities. The goal of the producer is to maximize profit while trying to satisfy these orders to the greatest extent. Fuzzy Set Theory is applied to construct a Fuzzy Chance-Constrained Production Mix Model (FCCPMM to enable the risk attitude of the decision maker to be adopted to address uncertainty.Theoretical evidence is supported by numerical illustration
ABCD Matrices as Similarity Transformations of Wigner Matrices and Periodic Systems in Optics
Baskal, S
2008-01-01
The beam transfer matrix, often called the $ABCD$ matrix, is a two-by-two matrix with unit determinant, and with three independent parameters. It is noted that this matrix cannot always be diagonalized. It can however be brought by rotation to a matrix with equal diagonal elements. This equi-diagonal matrix can then be squeeze-transformed to a rotation, to a squeeze, or to one of the two shear matrices. It is noted that these one-parameter matrices constitute the basic elements of the Wigner's little group for space-time symmetries of elementary particles. Thus every $ABCD$ matrix can be written as a similarity transformation of one of the Wigner matrices, while the transformation matrix is a rotation preceded by a squeeze. This mathematical property enables us to compute scattering processes in periodic systems. Laser cavities and multilayer optics are discussed in detail. For both cases, it is shown possible to write the one-cycle transfer matrix as a similarity transformation of one of the Wigner matrices....
Review of nuclear air treatment system related License Event Reports for the period 1985 - 1987
International Nuclear Information System (INIS)
This paper will continue the review of HVAC/NATS related LERS presented at past Air Cleaning Conferences by Dr. D. W. Moeller and his associates. The general approach and format are similar. LER abstracts from mid 1985 through 1987 were reviewed and those related to HVAC/NATS classified and analyzed. The categories were jointly developed by Dr. Moeller, Dr. Casper Sun and myself. In appropriate cases both primary and secondary categories fora problem are given. A basic listing by category and brief statistical review are presented. Additionally a number of categories are discussed in some detail. The categories chosen for specific review are intended to highlight particular problem areas. NUREG/CR-2000 License Event Report (LER) Compilation is the basis for the initial review and coding. In essentially all cases where an LER is classified as of interest the complete LER was obtained and reviewed in full. The intent of this paper is to provide a basis for the industry to document and analyze problem areas that require additional attention. It appears that about 15% of all LERS in the subject period are HVAC/NATS related. This figure is generally consistent with those reported at the 17th DOE Nuclear Air Cleaning Conference. It is hoped that such attention will allow additional resources to be allocated to upgrade systems, procedures and training as well as in some cases government regulation
Vasile Dragan; Toader Morozan; Adrian Mihail Stoica
2013-01-01
The purpose of the paper is to present a design procedure of theoptimal filter for discrete-time stochastic linear system with periodic coefficients simultaneously affected by a non-homogeneous but periodic Markov chain and state multiplicative white noise perturbations. The optimal filter minimizes a performance index described by the Cesaro limit of the mean square of the deviations of the signal generated by the filter from the values of the signal which must be estimated. It is proved tha...
Energy Technology Data Exchange (ETDEWEB)
Zhang Long [College of Mathematics and System Sciences, Xinjiang University, Urumqi 830046 (China)], E-mail: longzhang_xj@sohu.com; Teng Zhidong [College of Mathematics and System Sciences, Xinjiang University, Urumqi 830046 (China)], E-mail: zhidong@xju.edu.cn
2008-12-15
In this paper, we study two species predator-prey Lotka-Volterra type dispersal system with periodic coefficients in two patches, in which both the prey and predator species can disperse between two patches. By utilizing analytic method, sufficient and realistic conditions on permanence and the existence of periodic solution are established. The theoretical results are confirmed by a special example and numerical simulations.
International Nuclear Information System (INIS)
Nuclear standby safety systems must frequently, be submitted to periodic surveillance tests. The main reason is to detect, as soon as possible, the occurrence of unrevealed failure states. Such interventions may, however, affect the overall system availability due to component outages. Besides, as the components are demanded, deterioration by aging may occur, penalizing again the system performance. By these reasons, planning a good surveillance test policy implies in a trade-off between gains and overheads due to the surveillance test interventions. In order maximize the systems average availability during a given period of time, it has recently been developed a non-periodic surveillance test optimization methodology based on genetic algorithms (GA). The fact of allowing non-periodic tests turns the solution space much more flexible and schedules can be better adjusted, providing gains in the overall system average availability, when compared to those obtained by an optimized periodic tests scheme. The optimization problem becomes, however, more complex. Hence, the use of a powerful optimization technique, such as GAs, is required. Some particular features of certain systems can turn it advisable to introduce other specific constraints in the optimization problem. The Emergency Diesel Generation System (EDGS) of a Nuclear Power Plant (N-PP) is a good example for demonstrating the introduction of seasonal constraints in the optimization problem. This system is responsible for power supply during an external blackout. Therefore, it is desirable during periods of high blackout probability to maintain the system availability as high as possible. Previous applications have demonstrated the robustness and effectiveness of the methodology. However, no seasonal constraints have ever been imposed. This work aims at investigating the application of such methodology in the Angra-II Brazilian NPP EDGS surveillance test policy optimization, considering the blackout probability growth during summer, due to the electrical power demand increase. Here, the model used penalizes test interventions by a continuous modulating function, which depends on the instantaneous blackout probability. Results have demonstrated the ability of the method in adapting the surveillance tests policy to seasonal behaviors. The knowledge acquired by the GA during the searching process has lead to test schedules that drastically minimize the test interventions at periods of high blackout probability. It is compensated by more frequent tests redistributed through the periods of low blackout probability, in order to provide improvement on the overall average availability at the system level. (authors)
Hine, N D M; Haynes, P D; Skylaris, C K
2011-01-01
We present a comparison of methods for treating the electrostatic interactions of finite, isolated systems within periodic boundary conditions (PBCs), within Density Functional Theory (DFT), with particular emphasis on linear-scaling (LS) DFT. Often, PBCs are not physically realistic but are an unavoidable consequence of the choice of basis set and the efficacy of using Fourier transforms to compute the Hartree potential. In such cases the effects of PBCs on the calculations need to be avoided, so that the results obtained represent the open rather than the periodic boundary. The very large systems encountered in LS-DFT make the demands of the supercell approximation for isolated systems more difficult to manage, and we show cases where the open boundary (infinite cell) result cannot be obtained from extrapolation of calculations from periodic cells of increasing size. We discuss, implement and test three very different approaches for overcoming or circumventing the effects of PBCs: truncation of the Coulomb ...
Complex dynamics and switching transients in periodically forced Filippov prey–predator system
International Nuclear Information System (INIS)
Highlights: •We develop a Filippov prey–predator model with periodic forcing. •The sliding mode dynamics and its domain have been investigated. •The existence and stability of sliding periodic solution have been discussed. •The complex dynamics are addressed through bifurcation analyses. •Switching transients and their biological implications have been discussed. - Abstract: By employing threshold policy control (TPC) in combination with the definition of integrated pest management (IPM), a Filippov prey–predator model with periodic forcing has been proposed and studied, and the periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of the prey. This study aims to address how the periodic forcing and TPC affect the pest control. To do this, the sliding mode dynamics and sliding mode domain have been addressed firstly by using Utkin’s equivalent control method, and then the existence and stability of sliding periodic solution are investigated. Furthermore, the complex dynamics including multiple attractors coexistence, period adding sequences and chaotic solutions with respect to bifurcation parameters of forcing amplitude and economic threshold (ET) have been investigated numerically in more detail. Finally the switching transients associated with pest outbreaks and their biological implications have been discussed. Our results indicate that the sliding periodic solution could be globally stable, and consequently the prey or pest population can be controlled such that its density falls below the economic injury level (EIL). Moreover, the switching transients have both advantages and disadvantages concerning pest control, and the magnitude and frequency of switching transients depend on the initial values of both populations, forcing amplitude and ET
Ottino, Julio M.
1991-01-01
Computer flow simulation aided by dynamical systems analysis is used to investigate the kinematics of time-periodic vortex shedding past a two-dimensional circular cylinder in the context of the following general questions: (1) Is a dynamical systems viewpoint useful in the understanding of this and similar problems involving time-periodic shedding behind bluff bodies; and (2) Is it indeed possible, by adopting such a point of view, to complement previous analyses or to understand kinematical aspects of the vortex shedding process that somehow remained hidden in previous approaches. We argue that the answers to these questions are positive. Results are described.
International Nuclear Information System (INIS)
A series of 62 critical and critical approach experiments were performed to evaluate a possible novel means of storing large volumes of fissile solution in a critically safe configuration. This study is intended to increase safety and economy through use of such a system in commercial plants which handle fissionable materials in liquid form. The fissile solution's concentration may equal or slightly exceed the minimum-critical-volume concentration; and experiments were performed for high-enriched uranium solution. Results should be generally applicable in a wide variety of plant situations. The method is called the 'Poisoned Tube Tank' because strong neutron absorbers (neutron poisons) are placed inside periodically spaced stainless steel tubes which separate absorber material from solution, keeping the former free of contamination. Eight absorbers are investigated. Both square and triangular pitched lattice patterns are studied. Ancillary topics which closely model typical plant situations are also reported. They include the effect of removing small bundles of absorbers as might occur during inspections in a production plant. Not taking the tank out of service for these inspections would be an economic advantage. Another ancillary topic studies the effect of the presence of a significant volume of unpoisoned solution close to the Poisoned Tube Tank on the critical height. A summary of the experimental findings is that boron compounds were excellent absorbers, as expected. This was true for granular materials such as Gerstley Borate and Borax; but it was also true for the flexible solid composed of boron carbide and rubber, even though only thin sheets were used. Experiments with small bundles of absorbers intentionally removed reveal that quite reasonable tanks could be constructed that would allow a few tubes at a time to be removed from the tank for inspection without removing the tank from production service
De Velasco, P C; Sandre, P C; Tavares Do Carmo, M G; Faria-Melibeu, A C; Campello-Costa, P; Ferraz, A C; Andrade Da Costa, B L S; Serfaty, C A
2015-07-30
Retinocollicular connections form precise topographical maps that are normally completed through the selective elimination of misplaced axons and the stabilization of topographically ordered axon terminals during early development. Omega-3 fatty acids, acquired exclusively through the diet, and its main metabolite, docosahexaenoic acid (DHA), are involved in brain development and synaptic maturation. We have previously shown that the nutritional restriction of omega-3/DHA results in abnormal retinocollicular topographical fine-tuning. Therefore, we studied the role of omega-3 fatty acids nutritional supplementation and the developmental time windows during which this postnatal supplementation would restore normal topographical maps in the visual system. Female rats and their litters were chronically fed with either control (soy oil) or restricted omega-3 (coconut oil) diets. Fish oil supplementation was introduced between either postnatal day (PND) 7-13, PND7-28 or PND21-42. At PND13, PND28 or PND42, animals received an anterograde eye injection of a neuronal tracer to visualize retinocollicular axons. Confirming previous observations we found that an omega-3/DHA deficiency resulted in an abnormally high innervation density of retinal axons at the visual layers of the superior colliculus (SC). Although a short-term fish oil supplementation between PND7-13 could not restore normal retinocollicular topography, an extended treatment between PND7-28 completely recovered normal innervation densities of retinotectal axons. However, a late onset supplementation protocol, between PND28-42, was no longer effective in the restoration of the abnormal topographical pattern induced by an early omega-3 nutritional malnutrition. The results suggest a critical period for omega3/DHA dietary intake for the proper development of visual topographical maps. PMID:25916576
Energy Technology Data Exchange (ETDEWEB)
Rothe, R.E.
1996-09-30
A series of 62 critical and critical approach experiments were performed to evaluate a possible novel means of storing large volumes of fissile solution in a critically safe configuration. This study is intended to increase safety and economy through use of such a system in commercial plants which handle fissionable materials in liquid form. The fissile solution`s concentration may equal or slightly exceed the minimum-critical-volume concentration; and experiments were performed for high-enriched uranium solution. Results should be generally applicable in a wide variety of plant situations. The method is called the `Poisoned Tube Tank` because strong neutron absorbers (neutron poisons) are placed inside periodically spaced stainless steel tubes which separate absorber material from solution, keeping the former free of contamination. Eight absorbers are investigated. Both square and triangular pitched lattice patterns are studied. Ancillary topics which closely model typical plant situations are also reported. They include the effect of removing small bundles of absorbers as might occur during inspections in a production plant. Not taking the tank out of service for these inspections would be an economic advantage. Another ancillary topic studies the effect of the presence of a significant volume of unpoisoned solution close to the Poisoned Tube Tank on the critical height. A summary of the experimental findings is that boron compounds were excellent absorbers, as expected. This was true for granular materials such as Gerstley Borate and Borax; but it was also true for the flexible solid composed of boron carbide and rubber, even though only thin sheets were used. Experiments with small bundles of absorbers intentionally removed reveal that quite reasonable tanks could be constructed that would allow a few tubes at a time to be removed from the tank for inspection without removing the tank from production service.
Chemiluminescence determination of mezlocillin by the luminol-potassium periodate system
Scientific Electronic Library Online (English)
Wen Bing, Shi; Ji Dong, Yang.
Full Text Available Um método novo, simples e sensível foi proposto para a determinação de mezlocilina. Baseia-se na amplificação da emissão de quimiluminescência (CL) gerada a partir da oxidação do luminol em meio alcalino pelo periodato de potássio. A otimização das variáveis experimentais e instrumentais que afetam [...] o efeito da amplificação de CL foi realizada usando-se sistema de injeção em fluxo. Em condições ótimas, o método é eficiente para determinar mezlocilina no intervalo linear de 0,01 a 30 ×10-6 g mL-1 com limite de detecção (3?) de 3,0×10-9 g mL-1 e desvio padrão relativo (RSD) de 1,0% para 1,0×10-6 g mL-1 de mezlocilina (n=11). O método tem sido aplicado com sucesso, para determinação de mezlocilina em preparações comerciais, amostras sintéticas e formulações biológicas fluidas. Abstract in english A new, simple and sensitive method has been proposed for the determination of mezlocillin. It is based on the enhancement of the chemiluminescence (CL) emission generated from the oxidation of luminol in alkaline medium by postassium periodate. The optimization of the experimental and instrumental v [...] ariables affecting the CL enhancement effect has been carried out using flow-injection system. In the optimum conditions, the method is efficient to determine mezlocillin in the linear range of 0.01-30×10-6 g mL-1 with a detection limit (3?) of 3.0×10-9 g mL-1 and the relative standard deviation (RSD) is 1.0% for 1.0×10-6 g mL-1 mezlocillin (n=11). It has been successfully applied to the mezlocillin determination in commercial preparations, synthetic samples and biological fluids formulations.
Transient flow analysis in reactor coolant pump systems during flow coastdown period
Energy Technology Data Exchange (ETDEWEB)
Gao Hong, E-mail: hgao@sjtu.edu.c [Institute of Design and Control Engineering for Heavy Equipment, State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, No. 800 Dong Chuan Road, Shanghai 200240 (China); Gao Feng; Zhao Xianchao; Chen Jie; Cao Xuewu [Institute of Design and Control Engineering for Heavy Equipment, State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, No. 800 Dong Chuan Road, Shanghai 200240 (China)
2011-02-15
The rapid flow transient calculation in reactor coolant pump system is important in the safety analysis of a nuclear reactor. An accurate transient analysis of flow coastdown is also important and necessary for the design and manufacture of a reactor coolant pump. Only under the reliable work of a reactor coolant pump the safety of a nuclear power plant can be guaranteed. A mathematical model is developed for solving flow rate transient and pump speed transient during flow coastdown period. The detailed information of the centrifugal pump characteristics is not required. The flow rate and pump speed are solved analytically. The analytic solution of non-dimensional flow rate indicates that non-dimensional flow rate is determined by energy ratio {beta}. The kinetic energy of the loop coolant fluid and the kinetic energy stored in the rotating parts are two important parameters in form of {beta}. When the steady-state flow rate and pump speed are constant, the inertia of primary loop fluid and the pump moment of inertia are also two important parameters in flow transient analysis. For the condition all pump shafts are seized, the flow decay depends on the inertia of primary loop fluid. For the case that pump inertia is very large, the flow decay is determined by the pump inertia. The calculated non-dimensional flow rate and non-dimensional pump speed using the model are compared with published experimental data of two nuclear power plants and a reactor model test on flow coastdown transients. The comparison results show a good agreement. As the flow rate approaches to zero, the increase difference between experimental and calculated value is due to the effect of the mechanical friction loss.
Directory of Open Access Journals (Sweden)
Vasile Dragan
2013-07-01
Full Text Available The purpose of the paper is to present a design procedure of theoptimal filter for discrete-time stochastic linear system with periodic coefficients simultaneously affected by a non-homogeneous but periodic Markov chain and state multiplicative white noise perturbations. The optimal filter minimizes a performance index described by the Cesaro limit of the mean square of the deviations of the signal generated by the filter from the values of the signal which must be estimated. It is proved that the optimal lter with respect to the considered performance criterion has a Luenberger observer form which gain depends on the unique periodic solution of a discrete-time linear equation together with the stabilizing solution of a suitable discrete-time Riccati typeequation with periodic coefficients. The theoretical developments are illustrated by a numerical example.
Period-3 catastrophe and enhanced diffusion in two-dimensional Hamiltonian systems
International Nuclear Information System (INIS)
Quantitative analysis of the period-3 catastrophe is developed for the standard map and for the stochastic heating map as illustrative examples of two-dimensional area preserving mappings. Analytic expression of the diffusion coefficient is derived for the stochastic heating, and compared to results of numerical observation. Here, as for the case of the standard map, the multi-periodic accelerator modes give rise to anomalous enhancement of the diffusion rate. (author)
Orbital period derivative of a binary system using an exact orbital energy equation
Zaveri, Vikram H.
2007-01-01
It is proposed that the equations of motion in periodic relativity which yielded major predictions of general relativity without utilizing Riemannian geometry and geodesic trajectories are exact in nature and can be applied to pulsars and inspiraling compact binaries for analyzing orbital period derivative and two polarization gravitational wave forms. Exactness of these equations eliminates the need for higher order xPN corrections to the orbital energy part of the balance ...
Effects of periodic force on the stability of the metastable state in logistic system
Yang, Lin-Jing; Lv, Feng; Mei, Dong-Cheng
2015-08-01
The effects of periodic force on the stability of the metastable state in logistic model are investigated. The expression of the mean first-passage time (MFPT) from the metastable state to the stable state is derived. Based on the expression, the effects of periodic force on the MFPT were analyzed. The results indicate that: (i) For the case of the multiplicative noise induced transition, the multiplicative noise and the periodic force weaken the stability of the metastable state; (ii) For the case of the additive noise induced transition, the stability of the metastable state is weakened by the additive noise when the periodic force takes value of the first half cycle, while the stability of the metastable state is enhanced by the additive noise when the periodic force takes value of the second half cycle; (iii) For the case of the correlation between the multiplicative and the additive noise induced transition, the correlation between the multiplicative and the additive noises and the periodic force weaken the stability of the metastable state.
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Francineudo Alves Silva
2015-02-01
Full Text Available Led-if this work aimed to evaluate the effect of Indian summer periods about the productivity of corn for silage grown in no-tillage and conventional systems.The experiment was conducted in split plots, distributed in randomized block design, and systems were evaluated plots of no-till and conventional tillage and subplots, six periods of dry spells (2, 6, 10, 14, 18 and 22 days applied from the 34 days after planting, respectively.The crop was irrigated by drip, with individual control of the water supply in each sub-plot, for interruption of the water supply during periods of Indian summer, as well as the irrigation management outside the periods of Indian summer, which was carried out separately for each sub-plot, based on soil water tension, in order to allow for the measurement of water consumption in the cycle of culture.It was found that Indian summer periods of 6, 10, 14, 18 and 22 days reduced dry matter productivity of corn for silage in 8.74; 26.47; 42.5; 48.05 and 64.60% of no-till and in 16.42; 32.04; 47.38; 65.23 and 74.19% in conventional tillage, respectively. The no-tillige system reduced consumption and improved water use efficiency in the production of corn for silage, reduced losses caused by water deficit.
Czech Academy of Sciences Publication Activity Database
Kuzmych, O.; Mukhigulashvili, Sulkhan; P?ža, B.
2010-01-01
Ro?. 11, ?. 1 (2010), s. 63-77. ISSN 1787-2405 Institutional research plan: CEZ:AV0Z10190503 Keywords : higher order linear functional differential system * periodic boundary value problem * uniqueness Subject RIV: BA - General Mathematics http://mat76.mat.uni-miskolc.hu/~mnotes/index.php?page=article&name=mmn_300
DEFF Research Database (Denmark)
Allen, Matthew S.; Sracic, Michael W.
2011-01-01
Many important systems, such as wind turbines, helicopters and turbomachinery, must be modeled with linear time-periodic equations of motion to correctly predict resonance phenomena. Time periodic effects in wind turbines might arise due to blade-to-blade manufacturing variations, stratification in the velocity of the wind with height and changes in the aerodynamics of the blades as they pass the tower. These effects may cause parametric resonance or other unexpected phenomena, so it is important to properly characterize them so that these machines can be designed to achieve high reliability, safety, and to produce economical power. This work presents a system identification methodology that can be used to identify models for linear, periodically time-varying systems when the input forces are unmeasured, broadband and random. The methodology is demonstrated for the well-known Mathieu oscillator and then used to interrogate simulated measurements from a rotating wind turbine. The measurements were simulated for a 5 MW turbine modeled in the HAWC2 simulation code, which includes both structural dynamic and aerodynamic effects. This simulated system identification provides insights into the test and measurement requirements and the potential pitfalls, and simulated experiments such as this may be useful to obtain a set of time-periodic equations of motion from a numerical model, since a closed form model is not readily available by other means due to the way in which the aeroelastic effects are treated in the simulation code.
International Nuclear Information System (INIS)
The paper presents a procedure for optimal one year unit commitment in Bulgarian electric power system during the transitional period to wholesale market, combining certain classical theoretical models with heuristic methods. Comments are made on the transition from yearly commitment to weekly and daily dispatching control. The stages of the theory and practices for results optimality
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Kaihong Zhao
2011-04-01
Full Text Available Using Mawhin's continuation theorem of coincidence degree theory, we establish the existence of $2^{n+m}$ positive periodic solutions for a non-autonomous Lotka-Volterra network-like predator-prey system with harvesting terms. Here n and m denote the number of prey and predator species respectively. An example is given to illustrate our results.
Weak interactions in Graphane/BN systems under static electric fields—A periodic ab-initio study.
Steinkasserer, Lukas Eugen Marsoner; Gaston, Nicola; Paulus, Beate
2015-04-21
Ab-initio calculations via periodic Hartree-Fock (HF) and local second-order Møller-Plesset perturbation theory (LMP2) are used to investigate the adsorption properties of combined Graphane/boron nitride systems and their response to static electric fields. It is shown how the latter can be used to alter both structural as well as electronic properties of these systems. PMID:25903899
Liu, Quan-Xing,; Li, Bai-Lian; Jin, Zhen
2007-01-01
In this paper, we present a spatial version of phytoplankton-zooplankton model that includes some important factors such as external periodic forces, noise, and diffusion processes. The spatially extended phytoplankton-zooplankton system is from the original study by Scheffer [M Scheffer, Fish and nutrients interplay determines algal biomass: a minimal model, Oikos \\textbf{62} (1991) 271-282]. Our results show that the spatially extended system exhibit a resonant patterns an...
Tunable wideband bandstop acoustic filter based on 2D multi-physical phenomena periodic systems
Romero-García, V; Garcia-Raffi, L M
2011-01-01
The physical properties of a periodic distribution of absorbent resonators is used in this work to design a tunable wideband bandstop acoustic filter. Analytical and numerical simulations as well as experimental validations show that the control of the resonances and the absorption of the scatterers along with their periodic arrangement in air introduces high technological possibilities to control noise. Sound manipulation is perhaps the most obvious application of the structures presented in this work. We apply this methodology to develop a device as an alternative to the conventional acoustic barriers with several properties from the acoustical point of view but also with additional aesthetic and constructive characteristics.
76 FR 12300 - Safety Management System for Certificated Airports; Extension of Comment Period
2011-03-07
...10-14] RIN 2120-AJ38 Safety Management System for Certificated Airports...certificate holder to establish a safety management system (SMS) for its entire...No. 10-14, entitled ``Safety Management System for Certificated...
75 FR 76928 - Safety Management System for Certificated Airports; Extension of Comment Period
2010-12-10
...10-14] RIN 2120-AJ38 Safety Management System for Certificated Airports...certificate holder to establish a safety management system (SMS) for its entire...No. 10-14, entitled ``Safety Management System for Certificated...
76 FR 5296 - Safety Management System for Part 121 Certificate Holders; Extension of Comment Period
2011-01-31
...10-15] RIN 2120-AJ86 Safety Management System for Part 121 Certificate...121 to develop and implement a safety management system (SMS) to improve its...No. 10-15, entitled ``Safety Management Systems for Part 121...
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Soyalp Tamçelik
2014-12-01
Full Text Available In this research, regulations concerning the ‘temporary period’ in the new system sought to be established in Cyprus and its properties have been addressed. From this point of view, as the main purpose of this research, the regulations required during the talks taking place between the parties in Cyprus before a federal state is established and how the institutions expected to fulfill these will be structured have been observed. As could be understood from its name, temporary period reflects a certain period and is the period assumed to continue in Cyprus until the formation envisioned to be established there is achieved. Therefore, it is also possible to call this period a ‘transition period’. Actually, the most consistent for-mula that could be brought forward towards this period seems to be the formula of ‘temporary joint administration based on the principle of equality’. This formula, which is important for providing the necessary element of trust for negotiation particularly on issues of territory and constitution and also for displaying whether or not the functional properties of the federal state to be established is based upon a true foundation, appears for now as the most realistic method. On the other hand, the regulations to be made during the temporary period will come into effect with the preparation of the Federal Constitution and the Electoral Law, installing federal bureaucracy, analyzing property claims, determining economic development and protective provisions, regulations regarding territorial adjustments and through Committees, formed by the two communities, in charge of preparing the activity programme. Before a Federal Republic is established, a new state of partnership will emerge after the ‘Temporary Regulations’ enter into force. This partnership will reveal itself as a new state system organized within a framework of a federation that consists of two communities from a constitutional aspect and of two regions from a territorial aspect. Based on this fact, this research consists of two main sections. In the first section, regulations regarding the Temporary Period and other works to be conducted based on the Ghali Set of Ideas have been addressed. In the second and final section, regulations concerning the Temporary Period have been observed based on the Annan Plan.
International Nuclear Information System (INIS)
The abstracts of the XIX Mendeleev Congress on general and applied chemistry held 25-30 September 2011 in Volgograd are presented. The program includes the Congress plenary and section reports, poster presentations, symposia and round tables on key areas of chemical science and technology, and chemical education. The work of the Congress was held the following sections: 1. Fundamental problems of chemical sciences; 2. Chemistry and technology of materials, including nanomaterials; 3. Physicochemical basis of metallurgical processes; 4. Current issues of chemical production, technical risk assessment; 5. Chemical aspects of modern power and alternative energy sources; 6. Chemistry of fossil and renewable hydrocarbons; 7. Analytical chemistry: new methods and instruments for chemical research and analysis; 8. Chemical education. Volume 3 contains the reports correspondence section participants Chemistry and technology of materials, including nanomaterials, abstracts of oral and poster presentations, messages of correspondence participants at meetings of the sections: Physicochemical basis of metallurgical processes; Topical issues of chemical production, technical risk assessment, reports roundtable Interaction chemistry and business, as well as an author index
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Cláudia Simone Madruga Lima
2010-12-01
Full Text Available A physalis (Physalis peruviana é uma pequena fruta com grandes potencialidades, que, associadas ao seu ciclo curto e às propriedades nutracêuticas, apresenta possibilidade de alto retorno econômico. O objetivo deste trabalho foi avaliar o sistema de tutoramento e a época de transplante mais adequados para o crescimento e a produção de frutos de P. peruviana nas condições edafoclimáticas do sul do Rio Grande do Sul. O trabalho foi desenvolvido em Pelotas, RS, na safra de 2007/2008. O transplante de mudas de physalis foi realizado em duas épocas (época 1, 21/11/2007 e época 2 15/01/2008, sendo as plantas tutoradas em quatro sistemas de condução (sistema "V" invertido, sistema triangular, sistema vertical com bambu e sistema vertical com fitilho, semelhantes aos utilizados na cultura do tomateiro. O delineamento experimental adotado foi de blocos casualizados, com três repetições, sendo cada um representado por dez plantas. Os tratamentos formaram um fatorial 2x4 (épocas de transplante x sistemas de tutoramento. As variáveis analisadas foram: incremento do comprimento e da área da seção do ramo principal, área da seção do ramo principal, produtividade e eficiência produtiva. Foi evidenciado que a primeira época de transplante associada aos sistemas de tutoramento "V" invertido e triangular proporciona melhor desempenho agronômico das plantas de physalis.The cape-gooseberry (Physalis peruviana is a small fruit with great potentialities that whether associated to its short cycle and nutraceutical properties it shows high economical return. The work aimed to evaluate the best training system and replant period to plant growth, production and fruit quality of P. peruviana under edaphoclimatic at conditions of southern Rio Grande do Sul. The trial was carried out in Pelotas, RS, in 2007/2008 crop. Transplanting seedlings cape-gooseberry was conducted in two seasons Plant replanting was done in two periods (period 1, 21/11/2007 and period 2, 15/01/2008. Plants were trained under four systems (inverted "V" system, triangular system, vertical system using bamboo or vertical system using polypropylene cord, similarly to the tomato culture. Experimental design adopted was a complete randomized block in a 2x4 factorial (replant period x training system with three replications of ten plants each. The variables analyzed were: increment of length and section area of the main branch, section area of the main branch, yield and yield efficiency. It was evidenced that the first period of replant associated to the training systems inverted "V" and triangular improved the agronomical performance of cape-gooseberry plants.
Scientific Electronic Library Online (English)
Cláudia Simone Madruga, Lima; Michel Aldrighi, Gonçalves; Zeni Fonseca Pinto, Tomaz; Andrea De Rossi, Rufato; José Carlos, Fachinello.
2010-12-01
Full Text Available A physalis (Physalis peruviana) é uma pequena fruta com grandes potencialidades, que, associadas ao seu ciclo curto e às propriedades nutracêuticas, apresenta possibilidade de alto retorno econômico. O objetivo deste trabalho foi avaliar o sistema de tutoramento e a época de transplante mais adequad [...] os para o crescimento e a produção de frutos de P. peruviana nas condições edafoclimáticas do sul do Rio Grande do Sul. O trabalho foi desenvolvido em Pelotas, RS, na safra de 2007/2008. O transplante de mudas de physalis foi realizado em duas épocas (época 1, 21/11/2007 e época 2 15/01/2008), sendo as plantas tutoradas em quatro sistemas de condução (sistema "V" invertido, sistema triangular, sistema vertical com bambu e sistema vertical com fitilho), semelhantes aos utilizados na cultura do tomateiro. O delineamento experimental adotado foi de blocos casualizados, com três repetições, sendo cada um representado por dez plantas. Os tratamentos formaram um fatorial 2x4 (épocas de transplante x sistemas de tutoramento). As variáveis analisadas foram: incremento do comprimento e da área da seção do ramo principal, área da seção do ramo principal, produtividade e eficiência produtiva. Foi evidenciado que a primeira época de transplante associada aos sistemas de tutoramento "V" invertido e triangular proporciona melhor desempenho agronômico das plantas de physalis. Abstract in english The cape-gooseberry (Physalis peruviana) is a small fruit with great potentialities that whether associated to its short cycle and nutraceutical properties it shows high economical return. The work aimed to evaluate the best training system and replant period to plant growth, production and fruit qu [...] ality of P. peruviana under edaphoclimatic at conditions of southern Rio Grande do Sul. The trial was carried out in Pelotas, RS, in 2007/2008 crop. Transplanting seedlings cape-gooseberry was conducted in two seasons Plant replanting was done in two periods (period 1, 21/11/2007 and period 2, 15/01/2008). Plants were trained under four systems (inverted "V" system, triangular system, vertical system using bamboo or vertical system using polypropylene cord), similarly to the tomato culture. Experimental design adopted was a complete randomized block in a 2x4 factorial (replant period x training system) with three replications of ten plants each. The variables analyzed were: increment of length and section area of the main branch, section area of the main branch, yield and yield efficiency. It was evidenced that the first period of replant associated to the training systems inverted "V" and triangular improved the agronomical performance of cape-gooseberry plants.
Johnson, Mathew A.; Zumbrun, Kevin
Extending previous results of Oh-Zumbrun and Johnson-Zumbrun, we show that spectral stability implies linearized and nonlinear stability of spatially periodic traveling wave solutions of viscous systems of conservation laws for systems of generic type, removing a restrictive assumption that wave speed be constant to first order along the manifold of nearby periodic solutions. Key to our analysis is a nonlinear cancellation estimate observed by Johnson and Zumbrun, along with a detailed understanding of the Whitham averaged system. The latter motivates a careful analysis of the Bloch perturbation expansion near zero frequency and suggests factoring out an appropriate translational modulation of the underlying wave, allowing us to derive the sharpened low-frequency estimates needed to close the nonlinear iteration arguments.
International Nuclear Information System (INIS)
It is known that natural systems are undeniably subject to random fluctuations, arising from either environmental variability or internal effects. In this paper, we present a spatial version of the phytoplankton–zooplankton model that includes some important factors such as external periodic forces, noise, and diffusion processes. The spatially extended phytoplankton–zooplankton system is from the original study by Scheffer (Scheffer 1991 Oikos 62 271). Our results show that the spatially extended system exhibits a resonant pattern and frequency-locking phenomena. The system also shows that the noise and the external periodic forces play a constructive role in the Scheffer's model: (i) the noise can enhance the oscillation of phytoplankton species' density and form large clusters in space when the noise intensity is within a certain interval; (ii) the external periodic forces can induce 4:1 and 1:1 frequency-locking and spatially homogeneous oscillation phenomena to appear; and (iii) resonant patterns are observed in the system when the spatial noises and external periodic forces are both turned on. Moreover, we find that the 4:1 frequency locking transforms into 1:1 frequency locking when the noise intensity is increased. In addition to elucidating our results outside the domain of Turing instability, we provide further analysis of linear stability with the help of numerical calculation using the Maple software. Significantly, oscillations are enhanced in the system when the noise term is present. These results indicate that the oceanic plankton bloom may be partly due to interplay between the stochastic factors and external forces instead of deterministic factors. These results also may help us to understand the effects arising from the undeniable susceptibility to random fluctuations in oceanic plankton bloom
Directory of Open Access Journals (Sweden)
Paulo Fortes Neto
2011-12-01
Full Text Available Education institutions are potential generators of large volumes of domestic sewage. Studies of natural systems for effluent treatment have shown good efficiency and low cost compared to traditional systems. This makes them suitable for various segments of society, including educational institutions. A characteristic shared by most educational institutions is that they have the same academic calendars that include a long period of recess when, in many cases, the flow of sewage systems drops to almost zero, causing damage to both macrophytes in sewage bed and their associated microorganisms. This study aimed to evaluate the efficiency of a wetland system in an educational institution, after the recess period. It was observed for 45 days if there were signs of natural recovery, without any intervention. After this period, 15 seedlings of Thypha sp. were planted in the sewage bed, and analyses were performed for 45 additional days. The system efficiency in reducing turbidity, NH3, NO3- and phosphorus was, respectively, 63.0%, 21.7%, 31.1% and 20.3%, and for BOD, COD and thermotolerant coliforms, the average efficiency was 46.0%, 29.7% and 44.0%, respectively. If considered only the period after planting the results improved, with the following results: turbidity = 78.2%, 38.0% = NH3, NO3- = 53.2% = 25.6% phosphorus, BOD = 66, 2% = 36.5% COD and thermotolerant coliform = 60.7%. The results demonstrated the importance of vegetation bed for the efficiency of such treatment system.
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Constanta ENEA
2014-02-01
Full Text Available Since the formation of the United Principalities (24/01/1859, Romania has undergone a series of profound, permanent reforms of its fundamental institutions. The international context had an influence important, often enteritis in shaping its institutions, including the system of taxes. We plan to make a brief review of taxation in modern Romania, starting from the formation of the United Principalities (1859 via the international recognition of Romania as a kingdom (1881, the formation of the National Unitary (1918 international recognition (1919 - 1921, the interwar period (1918-1939, the Second world War (1939-1945 suffered territorial losses in 1940 , the communist period (1945-1989, the post-communist period (1989-2006, will deepen in a future article pre and post EU accession in terms of fiscal and customs.
International Nuclear Information System (INIS)
We numerically study coherent tunneling oscillations of the particles between two levels in a double-well potential in the presence of anharmonic periodic potentials. Extremely short driving pulses modify the tunneling coefficient to ?eff=? cos A, where ? is the bare tunneling coefficient without the driving field and A is the pulse area of the driving wave form. The modulation amplitude of the ?eff gradually decreases as the driving wave form becomes broad and is given by ?eff=?J0(A) for the sinusoidal modulation, where J0(x) denotes the ordinary Bessel function of order zero. Theoretical derivation of the effective tunneling coefficient ?eff=? cos A is also shown for a periodic ? kick with alternating sign by means of the transfer matrix formula
Orbital period derivative of a binary system using an exact orbital energy equation
Zaveri, Vikram H
2007-01-01
It is proposed that the equations of motion that yielded two major predictions of general relativity without utilizing Riemannian geometry and geodesic trajectories are exact in nature and can be applied to pulsars and inspiralling compact binaries for analyzing orbital period derivative and two polarization gravitational wave forms. Exactness of these equations eliminates the need for higher order xPN corrections to the orbital energy part of the balance equation.
Hine, Nicholas D. M.; Dziedzic, Jacek; Haynes, Peter D.; Skylaris, Chris-Kriton
2011-11-01
We present a comparison of methods for treating the electrostatic interactions of finite, isolated systems within periodic boundary conditions (PBCs), within density functional theory (DFT), with particular emphasis on linear-scaling (LS) DFT. Often, PBCs are not physically realistic but are an unavoidable consequence of the choice of basis set and the efficacy of using Fourier transforms to compute the Hartree potential. In such cases the effects of PBCs on the calculations need to be avoided, so that the results obtained represent the open rather than the periodic boundary. The very large systems encountered in LS-DFT make the demands of the supercell approximation for isolated systems more difficult to manage, and we show cases where the open boundary (infinite cell) result cannot be obtained from extrapolation of calculations from periodic cells of increasing size. We discuss, implement, and test three very different approaches for overcoming or circumventing the effects of PBCs: truncation of the Coulomb interaction combined with padding of the simulation cell, approaches based on the minimum image convention, and the explicit use of open boundary conditions (OBCs). We have implemented these approaches in the ONETEP LS-DFT program and applied them to a range of systems, including a polar nanorod and a protein. We compare their accuracy, complexity, and rate of convergence with simulation cell size. We demonstrate that corrective approaches within PBCs can achieve the OBC result more efficiently and accurately than pure OBC approaches.
The existence of periodic orbits and invariant tori for some 3-dimensional quadratic systems.
Jiang, Yanan; Han, Maoan; Xiao, Dongmei
2014-01-01
We use the normal form theory, averaging method, and integral manifold theorem to study the existence of limit cycles in Lotka-Volterra systems and the existence of invariant tori in quadratic systems in ?(3). PMID:24982980
Progress report of the CEC project Rodos system development. Period: 1 september 92-31 august 93
International Nuclear Information System (INIS)
Within the context of the Radioprotection program of the CEC, the RODOS project (Real-time On-line DecisiOn Support system) aims at the development of a decision support system for nuclear emergencies. RODOS involves 22 research teams, divided in 4 sub-projects: 'Meteorology and Atmospheric Dispersion, 'System Development', 'Decision Aiding Techniques'. The fourth sub-project is a Joint Study Project of the Agreement between CEC ad the CIS republics. EDF is working in the 'System Development' sub-project and namely in the 'training' group. This group aims at the creation of a specific training course for health physics managers, based on RODOS. This note reproduces the progress report of the 'Development System' project. The reporting period is: September 92 - August 93. Progress bas been made within the reporting period in the: - development of data assimilation methods incorporating both monitoring data and model predictions for obtaining consistent pictures of the environmental contamination and the source term ; - improvement and extension of the modules ATSTEP-CORA (atmospheric dispersion and deposition), EMERSIM (simulation of emergency actions), ECOAMOR (exposure pathways and dose calculation) and FRODO (simulation of relocation and agricultural countermeasures) ; - preparation of training courses using RODOS as illustrative tool ; - extension of the functions of the RODOS operating system OSY, in particular of RoGIS, its geographical information system. (author). 2 figs
Energy Technology Data Exchange (ETDEWEB)
de la Hoz, Jordi; Boix, Oriol; Martin, Helena [Department of Electrical Engineering, Universitat Politecnica de Catalunya (UPC), Escola Tecnica d' Enginyeria Industrial de Barcelona (EUETIB), Carrer del Comte d' Urgell, 187, 08036 Barcelona (Spain); Martins, Blanca [Department of Business Management, Universitat Politecnica de Catalunya (UPC), Escola Tecnica d' Enginyeria Industrial de Barcelona (EUETIB), Carrer del Comte d' Urgell, 187, 08036 Barcelona (Spain); Graells, Moises [Department of Chemical Engineering, Universitat Politecnica de Catalunya (UPC), Escola Tecnica d' Enginyeria Industrial de Barcelona (EUETIB), Carrer del Comte d' Urgell, 187, 08036 Barcelona (Spain)
2010-12-15
This paper contributes a critical view of the development of grid-connected photovoltaic systems (GCPVS) in Spain during the period 1998-2008 by looking into the different actions that were intended to promote this technology. The Spanish photovoltaic (PV) sector has undergone bullish development in the recent years, but its underlying factors still lack systematic identification and analysis. Accordingly, this paper collects and presents detailed data for describing this evolution. It also makes a special case of the particular promotion of PV systems on roof and goes further to analyze how these actions have affected GCPVS evolution as well as the magnitude of their impact on its performance. The exponential growth of installed cumulative PV power at the end of this period, which largely exceeded the target set for 2008, is canvassed by building an analogy with feedback control systems. In this approach, market response or the PV power attained is considered as the system output, while the different regulation changes are regarded as control actions aimed at enabling GCPVS to hit the energy target. Such an analysis allows determining the most significant delays and control actions that explain the system's performance. Hence, this study suggests an alternative framework to support the formulation and assessment of energy policy as it puts the emphasis not only on the evolution of the system per se but rather on the performance of the system against the energy target. In this regard, it might contribute to enhance the promotion mechanisms of green technologies. (author)
Stabilizing periodic orbits of chaotic systems using fuzzy control of Poincare map
International Nuclear Information System (INIS)
In this paper a fuzzy control algorithm is used to stabilize the fixed points of a chaotic system. No knowledge of the dynamic equations of the system is needed in this approach and the whole system is considered as a black box. Two main approaches have been investigated: fuzzy clustering and table look up methods. As illustrative examples these methods have been applied to Bonhoeffer van der Pol oscillator and the Henon chaotic system and the convergence toward fixed points is observed
Directory of Open Access Journals (Sweden)
D Manzoori
2009-12-01
Full Text Available The solutions of photometric BV light curves for the Algol like system UV Leo were obtained using Wilson-Devinney code. The physical and orbital parameters along with absolute dimensions of the system were determined. It has been found that to best fit the V light curve of the system, assumptions of three dark spots were necessary two on the secondary and one on the primary. The absolute visual magnitudes (Mv of the individual components i.e., primary and secondary were estimated to 4.41 and 4.43, respectively, through the color curve analysis. The period analysis of the system presented elsewhere, indicated a cyclic period change of 12 yr duration, which was attributed to magnetic activity cycle, as a main cause of period variation in the system, through the Applegate mechanism. To verify the Applegate model I preformed calculations of some related parameters barrowed from Apllegate and Kalimeris. Values of all the calculated parameters were in accordance to those obtained for similar systems by Applegate. The differential magnitudes ? B and ? V, along with corresponding values of ?(B-V color index. The cyclic variations in brightness are quite clear. There are three predictions of Applegate's theory concerning effects of cyclic magnetic changes on the period variations, which can be checked through the observations, these are as follows: I The long term variations in mean brightness (at outside of eclipses and cyclic changes of orbital period, vary with the same period. II The active star gets bluer as it gets brightened and/or the brightness and color variations are to be in phase. III Changes in luminosity due to changes in quadrupole moment should be of the order 0.1 mag. All the above mentioned predictions of Applegate’s theory are verified. These results combined with cyclic character of P(E presented elsewhere and also consistency of parameters which are obtained in this paper, led me to conclude that one the main causes of period variability in UV Leo system is magnetic activity cycle (newly presented here. Since both components (G0&G2 of this system magnetically can be active, and separation of the components is relatively low (3.9Rs, the magnetic braking could also cause the period change. The magnetized star winds move outward from the star, but are twisted due to rapid rotation of star. Charged particles in the stars wind become trapped in the star's magnetic field and are dragged along the field lines .The result is angular momentum (AM transfer from the star by magnetic field to the charged particles. As the winds leave the star surface they are dragged by the magnetic field which in turn slows down the star's rotation.
Hohenemser, K. H.; Prelewicz, D. A.
1974-01-01
Computer experiments are described which used transient responses in flap-bending and torsion of a rotor blade at high advance ratio. It was found that a simple system identification method applying a linear sequential estimator also called equation of motion estimator, is suitable for this periodic system and can be used directly, if only the acceleration data are noise-polluted. In the case where noise is also present in the state-variable data, the direct application of the estimator gave poor results. However after prefiltering the data with a digital Graham filter having a cutoff frequency above the natural blade torsion frequency, the linear sequential estimator successfully recovered the parameters of the periodic coefficient analytical model.
Quasi-Periodic Post-Critical Response Types of a Harmonically Excited Auto-Parametric System.
Czech Academy of Sciences Publication Activity Database
Náprstek, Ji?í; Fischer, Cyril
Kippen : Civil-Comp Press, 2011 - (B.H.V. Topping; Y. Tsompanakis), s. 1-26 ISBN 978-1-905088-46-1. ISSN 1759-3433. [International Conference on Civil, Structural and Environmental Engineering Computing /13./. Chania (GR), 06.09.2011-09.09.2011] R&D Projects: GA AV ?R(CZ) IAA200710805; GA ?R(CZ) GA103/09/0094; GA AV ?R(CZ) IAA200710902 Institutional research plan: CEZ:AV0Z20710524 Keywords : non-linear vibration * quasi-periodic response * spherical pendulum Subject RIV: JM - Building Engineering http://dx.doi.org/10.4203/ccp.96.77
A. P. Shete; Verma, A K; R. S. Tandel; Chandra Prakash; Tiwari, V.K.; Tanveer Hussain
2013-01-01
Experiment with varied water circulation periods having 4, 8, 12, and 24 hrs/day as T1, T2, T3 and T4, respectively in aquaponics, evaluated against a control (without aquaponics) revealed higher fish and plant growth in T3 and T4. The mean growth of fish varied significantly among treatments showing higher growth in T4 and control followed by T3, T2 and T1. Survival rate was 100% in all the treatments as well as control. Percentage weight gain, SGR (% day-1) also showed the similar trend as ...
The RTA betatron-node experiment: Limiting cumulative BBU growth in a linear periodic system
International Nuclear Information System (INIS)
The successful operation of a Two-Beam accelerator based on extended relativistic klystrons hinges upon decreasing the cumulative dipole BBU growth from an exponential to a more manageable linear growth rate. The authors describe the theoretical scheme to achieve this, and a new experiment to test this concept. The experiment utilizes a 1-MeV, 600-Amp, 200-ns electron beam and a short beamline of periodically-spaced rf dipole-mode pillbox cavities and solenoid magnets for transport. Descriptions of the beamline are presented, followed by theoretical studies of the beam transport and dipole-mode growth
Starkov, Konstantin E.
2015-07-01
In this paper we study invariant domains with unbounded dynamics for one cosmological Hamiltonian system which is formed by the conformally coupled field; this system was introduced by Maciejewski et al. (2007). We find a few groups of conditions imposed on parameters of this system for which all trajectories are unbounded in both of time directions. Further, we present a few groups of other conditions imposed on system parameters under which we localize the invariant domain with unbounded dynamics; this domain is defined with help of bounds for values of the Hamiltonian level surface parameter. We describe one group of conditions when our system possesses two periodic orbits found explicitly. In some of rest cases we get localization bounds for compact invariant sets.
Aizin, Gregory R.; Dyer, Gregory C.
2012-01-01
We present a comprehensive theory of the one-dimensional plasmonic crystal formed in the grating gated two-dimensional electron gas (2DEG) in semiconductor heterostructures. To describe collective plasma excitations in the 2DEG, we develop a generalized transmission line theoretical formalism consistent with the plasma hydrodynamic model. We then apply this formalism to analyze the plasmonic spectra of 2DEG systems with step-like periodic changes of electron density and/or g...
Raupach, Marc; Tonner, Ralf
2015-01-01
The development and first applications of a new periodic energy decomposition analysis (pEDA) scheme for extended systems based on the Kohn-Sham approach to density functional theory are described. The pEDA decomposes the binding energy between two fragments (e.g. the adsorption energy of a molecule on a surface) into several well-defined terms: preparation, electrostatic and dispersion interaction, Pauli repulsion and orbital relaxation energies. The pEDA presented here for...
Richardson, D. L.
1980-01-01
A third-order analytical solution for halo-type periodic motion about the collinear points of the circular-restricted problem is presented. The three-dimensional equations of motion are obtained by a Lagrangian formulation. The solution is constructed using the method of successive approximations in conjunction with a technique similar to the Lindstedt-Poincare method. The theory is applied to the sun-earth system.
Kikugawa, Gota; Nakano, Takeo; Ohara, Taku
2015-07-14
In the present study, we use molecular dynamics (MD) simulations to provide an insight into the system size effect on the self-diffusion coefficient of liquids in the periodic rectangular parallelepiped system, from the hydrodynamic perspective. We have previously shown that in the rectangular box system, the diffusivity exhibits anomalous behaviors, i.e., the diffusion tensor appears to be anisotropic despite the bulk liquid simulation and the diffusion component in the direction along the short side of rectangular box with a high aspect ratio exceeding the diffusivity in the infinite system [Kikugawa et al., J.Chem. Phys. 142, 024503 (2015)]. So far, the size effect on the diffusivity has been intensively studied in the cubic system and has been interpreted quite well by the theoretical considerations employing the hydrodynamic interaction. Here, we have extended the hydrodynamic theory to be applied to periodic rectangular box systems and compared the theoretical predictions with MD simulation results. As a result, the diffusivity predicted by the hydrodynamic theory shows good agreement with the MD results. In addition, the system size effect was examined in a rod-shaped rectangular box in which the two shorter side lengths were equivalent and a film-type rectangular box in which the two longer side lengths were equivalent. It is of interest that we found that the aspect ratio, at which the diffusivity coincides with that in the infinite system, is a universal constant independent of the cross-sectional area for the rod system or the thickness for the film system. By extracting the universal structure in the hydrodynamic description, we also suggested a simplified approximate model to accurately predict the size effect on the diffusivity over a practical range of aspect ratios. PMID:26178118
Kikugawa, Gota; Nakano, Takeo; Ohara, Taku
2015-07-01
In the present study, we use molecular dynamics (MD) simulations to provide an insight into the system size effect on the self-diffusion coefficient of liquids in the periodic rectangular parallelepiped system, from the hydrodynamic perspective. We have previously shown that in the rectangular box system, the diffusivity exhibits anomalous behaviors, i.e., the diffusion tensor appears to be anisotropic despite the bulk liquid simulation and the diffusion component in the direction along the short side of rectangular box with a high aspect ratio exceeding the diffusivity in the infinite system [Kikugawa et al., J.Chem. Phys. 142, 024503 (2015)]. So far, the size effect on the diffusivity has been intensively studied in the cubic system and has been interpreted quite well by the theoretical considerations employing the hydrodynamic interaction. Here, we have extended the hydrodynamic theory to be applied to periodic rectangular box systems and compared the theoretical predictions with MD simulation results. As a result, the diffusivity predicted by the hydrodynamic theory shows good agreement with the MD results. In addition, the system size effect was examined in a rod-shaped rectangular box in which the two shorter side lengths were equivalent and a film-type rectangular box in which the two longer side lengths were equivalent. It is of interest that we found that the aspect ratio, at which the diffusivity coincides with that in the infinite system, is a universal constant independent of the cross-sectional area for the rod system or the thickness for the film system. By extracting the universal structure in the hydrodynamic description, we also suggested a simplified approximate model to accurately predict the size effect on the diffusivity over a practical range of aspect ratios.
International Nuclear Information System (INIS)
Quasi-one-dimensional periodic systems were investigated by the new proposed extrapolation method. The effect of the selection of the different structural units and their spin states on the periodic system was also studied. A quantum chemical calculation investigation of a 28 quasi-one-dimensional periodic system with MNDO (UHF) and EHMO/ASED-EHCO/ASED was undertaken. Quantum chemical calculation results with the MNDO (UHF) method showed that the proposed new method could be applied in the situation of the more precise semiempirical method. The selection of the different structural units and their spin states do not affect the extrapolated structural unit energy. The energy of suspending terminal group is generally higher for those with a higher bond order. The interaction energy between the suspending terminal groups generally decreases with the chain length. Comparison between the extrapolation results of EHMO/ASED and those from the crystal orbital calculation of EHCO/ASED indicates their equivalence, thus confirming the validity of the proposed method. 25 refs., 6 figs., 6 tabs
Duarte, B; Santos, D; Marques, J C; Caçador, I
2014-04-01
Submergence is one of the major constrains affecting wetland plants, with inevitable impacts on their physiology and productivity. Global warming as a driving force of sea level rise, tend to increase the submersion periods duration. Photosynthesis biophysical probing arise as an important tool to understand the energetics underlying plant feedback to these constrains. As in previous studies with Spartina maritima, there was no inhibition of photosynthetic activity in submerged individuals. Comparing both donor and acceptor sides of the PSII, the first was more severely affected during submersion, driven by the inactivation of the OEC with consequent impairment of the ETC. Although this apparent damage in the PSII donor side, the electron transport per active reaction centre was not substantially affected, indicating that this reduction in the electron flow is accompanied by a proportional increase in the number of active reaction centres. These conditions lead to the accumulation of excessive reducing power, source of damaging ROS, counteracted by efficient energy dissipation processes and anti-oxidant enzymatic defences. This way, S. maritima appears as a well-adapted species with an evident photochemical plasticity towards submersion, allowing it to maintain its photosynthetic activity even during prolonged submersion periods. PMID:24630362
The effect of colostrum period management on BW and immune system in lambs: from birth to weaning.
Hernández-Castellano, L E; Suárez-Trujillo, A; Martell-Jaizme, D; Cugno, G; Argüello, A; Castro, N
2015-10-01
The aim of this study was to investigate the BW and immune status of lambs reared under natural conditions or under artificial conditions fed two different colostrum amounts. In this study, 60 lambs were randomly divided into groups according to treatment. Twenty lambs remained with their dams (natural rearing (NR) group). Forty lambs were removed from their dams at birth. Lambs were bottle-fed with a pool of sheep colostrum, receiving either 4 g of IgG/kg of BW at birth (C4 group) or 8 g of IgG/kg of BW at birth (C8 group). The total colostrum amount was equally divided into three meals at 2, 14 and 24 h after birth. After this period, lambs were bottle-fed a commercial milk replacer. Blood plasma sample analysis and BW recordings were carried out before feeding at birth and then at 1, 2, 3, 4, 5 and 20 days after birth. Another blood sample analysis and BW recording was carried out when animals reached 10 kg of BW. During weaning (30 days), sampling was carried out every 5 days. Blood plasma was used to determine the concentrations of IgG and IgM and the complement system activity - total and alternative pathways. The NR group showed greater BW than the C4 and C8 groups during milk feeding period, whereas the C4 and C8 groups had greater BW than the NR group at the end of weaning period. The C8 and NR groups had greater plasma IgG and IgM concentrations than the C4 group during milk feeding period. In addition, C4 and C8 groups showed similar IgG concentrations and greater IgM concentrations than the NR group at the end of the weaning period. Complement system activity was greater in the NR group than in the C4 and C8 groups during the first 3 days after birth. In conclusion, lambs fed amounts of colostrum equivalent to 8 g of IgG/kg of BW showed similar immune variables compared to lambs reared under natural conditions, obtaining a greater BW at the end of the weaning period. Nevertheless, this study shows that not only the colostrum amount but also the management during the milk feeding and weaning period, such as stress produced by dam separation, milk quality and suckling frequency, can affect the final immune status of lambs. PMID:26148573
Henderson, M. G.; Skoug, R.; Thomsen, M. F.; Borovsky, J.; Reeves, G. D.; Immel, T. J.; Mende, S. B.; Lui, A. T.
2003-12-01
During intervals of prolonged moderate but steady southward IMF Bz, the magnetosphere frequently enters a state in which quasi-periodic, large-amplitude, global oscillations are observed in the geosynchronous energetic particle fluxes. These oscillations have been termed ``sawtooth events" because their shape -- a series of slow flux decreases followed by rapid increases -- resemble the teeth of a saw blade. Recent studies of sawtooth events have shown that each of the flux increases are associated with characteristic substorm onset signatures including field dipolarization, injection of energetic particles, ground magnetic perturbations, and embedded auroral onsets. Thus, it has been shown that sawtooth events are actually a sequence of recurrent quasi-periodic substorms. In addition, the level of solar wind driving necessary to induce sawtooth behavior appears to be transitional between driving levels that give rise to SMC (steady magnetospheric convection) and full-blown storm type behavior. Sawtooth events can therefore be viewed as a magnetospheric mode similar to SMCs except that for sawtooth events, the flow of energy from the solar wind into the magnetosphere becomes too large to dissipate without the (literally) periodic occurrence of substorms. I.e., the magnetosphere is continuously ``driven'' toward substorm-like reconfigurations in order to ``reset'' itself at periodic intervals. In this presentation we examine the possibility that during such long-lived, predominantly driven events, the energy input to the ionosphere/atmosphere system is greatly enhanced by the continuously driven auroral disturbances that occur.
Directory of Open Access Journals (Sweden)
Santhi Baskaran
2010-12-01
Full Text Available Energy consumption is a critical design issue in real-time systems, especially in battery- operated systems. Maintaining high performance, while extending the battery life between charges is an interesting challenge for system designers. Dynamic Voltage Scaling (DVS allows a processor to dynamically change speed and voltage at run time, thereby saving energy by spreading run cycles into idle time.Knowing when to use full power and when not, requires the cooperation of the operating system scheduler. Usually, higher processor voltage and frequency leads to higher system throughput whileenergy reduction can be obtained using lower voltage and frequency. Instead of lowering processorvoltage and frequency as much as possible, energy efficient real-time scheduling adjusts voltage andfrequency according to some optimization criteria, such as low energy consumption or high throughput,while it meets the timing constraints of the real-time tasks. As the quantity and functional complexity ofbattery powered portable devices continues to raise, energy efficient design of such devices has becomeincreasingly important. Many real-time scheduling algorithms have been developed recently to reduceenergy consumption in the portable devices that use DVS capable processors. Extensive power awarescheduling techniques have been published for energy reduction, but most of them have been focusedsolely on reducing the processor energy consumption. While the processor is one of the major powerhungry units in the system, other peripherals such as network interface card, memory banks, disks alsoconsume significant amount of power. Dynamic Power Down (DPD technique is used to reduce energyconsumption by shutting down the processing unit and peripheral devices, when the system is idle. Threealgorithms namely Red Tasks Only (RTO, Blue When Possible (BWP and Red as Late as Possible (RLPare proposed in the literature to schedule the real-time tasks in Weakly-hard real-time systems. Thispaper proposes optimal slack management algorithms to make the above existing weakly hard real-timescheduling algorithms energy efficient using DVS and DPD techniques.
Perruisseau-Carrier, Julien
2007-01-01
As a result of the ever growing number of functionalities and standards to be supported by communication systems, as well as the constant development of radar and imaging technologies, a key research area in the field of microwaves and millimeter waves is the achievement of reconfigurability capabilities. In recent years, the progress of MicroElectroMechanical Systems (MEMS) fabrication techniques has allowed radically challenging the performances of reconfigurable devices based on establishe...
Energy Technology Data Exchange (ETDEWEB)
Wang Fengyan [College of Science, Jimei University, Xiamen Fujian 361021 (China)]. E-mail: wangfy68@163.com; Zeng Guangzhao [Department of Mathematics, ShaoGuan University, ShaoGuan, GuangDong 512005 (China)]. E-mail: guangzhaoz@sgu.edu.cn
2007-05-15
In this paper, we introduce and study a Lotka-Volterra predator-prey system with impulsive ratio-harvesting the prey and time delays. By using Floquet theory and small amplitude perturbation skills, we discuss the boundary periodic solutions for predator-prey system under periodic pulsed conditions. The stability analysis of the boundary periodic solution yields an invasion threshold of the predator. Further, by use of the coincidence degree theorem and its related continuous theorem we prove the existence of the positive periodic solutions of the system when the value of the coefficient is large than the threshold. Finally, by comparing bifurcation diagrams with different bifurcation parameters, we show that the impulsive effect and the time delays bring to the system to be more complex, which experiences a complex process of cycles {sup {yields}} quasi-periodic oscillation {sup {yields}} periodic doubling cascade {sup {yields}} chaos.
International Nuclear Information System (INIS)
In this paper, we introduce and study a Lotka-Volterra predator-prey system with impulsive ratio-harvesting the prey and time delays. By using Floquet theory and small amplitude perturbation skills, we discuss the boundary periodic solutions for predator-prey system under periodic pulsed conditions. The stability analysis of the boundary periodic solution yields an invasion threshold of the predator. Further, by use of the coincidence degree theorem and its related continuous theorem we prove the existence of the positive periodic solutions of the system when the value of the coefficient is large than the threshold. Finally, by comparing bifurcation diagrams with different bifurcation parameters, we show that the impulsive effect and the time delays bring to the system to be more complex, which experiences a complex process of cycles ? quasi-periodic oscillation ? periodic doubling cascade ? chaos
International Nuclear Information System (INIS)
Highlights: ? Relationships between pump heads and the parameters of a system are established. ? Relationships between pump torques and the parameters of a system are established. ? The variables are non-dimensionlized in order to design a new system and pump. ? All variables are solved analytically. Pump characteristics are not required. ? Mechanism of reactor coolant pump start-up is mathematically solved and clarified. - Abstract: The reactor coolant pump is “the heart” of a nuclear reactor and the only high-speed revolving equipment in a pressurized water reactor primary cooling loop system. The accurate prediction of flow and pump transient performance, during start-up transients, is a very important factor in the reactor coolant pumps design and the nuclear reactor design. Based on the momentum conservation equation of the primary coolant and the moment balance relation of the reactor coolant pump, the transient pump total head, the acceleration head and the overcoming friction head during a pump start up are derived. The relationship between the above heads and the parameters of the system fluid and pump is established too. Furthermore, the transient torques during a pump start-up are also derived. They include the torques required to accelerate the coolant fluid, to accelerate the pump rotating parts and to overcome friction of coolant fluid in the pipes system. The relation between the above three transient torques and the parameters of the coolant fluid and the pump is respectively established. In addition, the above variables are all non-dimensionlized in order to design a new system. The transient flow rate and pump speed are solved analytically. The detailed information of the centrifugal pump characteristics is not required. The analytical non-dimensional flow rate, the pump speed, heads and torques are all affected by an energy ratio ?. The effects of ? on the three transient heads and the three transient torques are discussed respectively. A comparison with Tsukamoto’s experimental results, during the pump start-up, shows an excellent agreement
Energy Technology Data Exchange (ETDEWEB)
Kramer, P [Theoretische Physik, University Tuebingen (Germany); Kramer, T [Institute for Theoretical Physics, University Regensburg (Germany); Man' ko, V I [Lebedev Physical Institute, Moscow (Russian Federation)], E-mail: peter.kramer@uni-tuebingen.de
2009-05-15
We consider classical and quantum propagators for two different time intervals. If these propagators follow one another in a Fibonacci sequence we get a discrete quasi-periodic system. A theorem due to Nielsen provides a novel conserved quantity for this system. The Nielsen quantity controls the transition between commutative and non-commutative propagation in time. The quasi-periodically kicked oscillator, moreover, is dominated by quasi-periodic analogues of the Floquet theorem.
Bott periodicity for Z2 symmetric ground states of gapped free-fermion systems
Kennedy, Ricardo
2014-01-01
Building on the symmetry classification of disordered fermions, we give a proof of the proposal by Kitaev, and others, for a "Bott clock" topological classification of free-fermion ground states of gapped systems with symmetries. Our approach differs from previous ones in that (i) we work in the standard framework of Hermitian quantum mechanics over the complex numbers, (ii) we directly formulate a mathematical model for ground states rather than spectrally flattened Hamiltonians, and (iii) we use homotopy-theoretic tools rather than K-theory. Key to our proof is a natural transformation that squares to the standard Bott map and relates the ground state of a d-dimensional system in symmetry class s to the ground state of a (d+1)-dimensional system in symmetry class s+1. This relation gives a new vantage point on topological insulators and superconductors.
Fuel Cell/Battery Powered Bus System. Final Report for period August 1987 - December 31, 1997
Energy Technology Data Exchange (ETDEWEB)
Wimmer, R.
1999-01-01
Today, fuel cell systems are getting much attention from the automotive industry as a future replacement for the internal combustion engine (ICE). Every US automobile manufacturer and most foreign firms have major programs underway to develop fuel cell engines for transportation. The objective of this program was to investigate the feasibility of using fuel cells as an alternative to the ICE. Three such vehicles (30-foot buses) were introduced beginning in 1994. Extensive development and operational testing of fuel cell systems as a vehicle power source has been accomplished under this program. The development activity investigated total systems configuration and effectiveness for vehicle operations. Operational testing included vehicle performance testing, road operations, and extensive dynamometer emissions testing.
International Nuclear Information System (INIS)
Proton magnetic resonance spectroscopic, vapor pressure osmometric and Karl Fischer titrimetric measurements have provided support for our earlier findings obtained from interfacial tension and mass transfer experiments that reversed micelles are formed, under certain conditions, in the system HDEHP/n-hexane/CaCl2 solution. These studies were further extended to include different organophosphorus acid (PC 88A), diluent (benzene), and metal ions (Co2+, Ni2+, and Zn2+) to determine whether reversed micellization is a general phenomenon occurring in solvent extraction systems which employ organophosphorus acids. The data obtained so far, suggest that reversed micellization indeed is a general phenomenon operative in organophosphorus acid extractant systems. A new mass transfer cell has been constructed in order to investigate the metal distribution equilibria and extraction kinetics of Co, Ni and Zn using atomic absorption spectrophotometric technique. A quasi-elastic light-scattering apparatus has been installed to investigate aggregation phenomena in solvent extraction systems. Preliminary drop-interface coalescence studies were performed, and the results were correlated with those obtained from interfacial tension measurements. The laser heterodyne light-scattering apparatus for measurement of interfacial viscoelastic properties also has been set-up and is being optimized for high resolution measurements. 21 refs., 16 figs
International Nuclear Information System (INIS)
We investigate the singularity structure analysis of the higher-dimensional time-gated Manakov system referring to the (2+1)-dimensional coupled nonlinear Schroedinger (CNLS) equations, and we show that these equations are Painleve-integrable. By means of the Weiss et al.'s methodology, we show the arbitrariness of the expansion coefficients and the consistency of the truncation corresponding to a special Baecklund transformation (BT) of these CNLS equations. In the wake of such transformation, following the Hirota's formalism, we derive a one-soliton solution. Besides, by using the Zakharov-Shabat (ZS) scheme which provides a general Lax-representation of an evolution system, we show that the (2+1)-dimensional CNLS system under interests is completely integrable. Furthermore, using the arbitrariness of the above coefficients, we unearth and investigate a typical spectrum of periodic coherent structures while depicting elastic interactions amongst such patterns. (author)
Energy Technology Data Exchange (ETDEWEB)
Huynh, K.T., E-mail: tuan.huynh@utt.f [Universite de technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279-12, rue Marie Curie, BP2060, 10010 Troyes cedex (France); Barros, A., E-mail: anne.barros@utt.f [Universite de technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279-12, rue Marie Curie, BP2060, 10010 Troyes cedex (France); Berenguer, C., E-mail: christophe.berenguer@utt.f [Universite de technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279-12, rue Marie Curie, BP2060, 10010 Troyes cedex (France); Castro, I.T., E-mail: inmatorres@unex.e [Departamento de Matematicas, Escuela Politecnica, 10071 Caceres (Spain)
2011-04-15
This paper deals with the condition-based maintenance of single-unit systems which are subject to the competing and dependent failures due deterioration and traumatic shock events. The main aim is to provide a model to assess the value of condition monitoring information for the maintenance decision-making. A condition-based periodic inspection/replacement policy is developed and compared with a benchmark time-based block replacement policy. Numerical results show that it is indeed useful to follow closely the actual evolution of the system to adapt the maintenance decisions to the true system state to improve the performance of maintenance policies. The analysis of the maintenance costs savings can be used to justify or not the choice to implement a policy based on condition monitoring information and to invest in condition monitoring devices.
International Nuclear Information System (INIS)
This paper deals with the condition-based maintenance of single-unit systems which are subject to the competing and dependent failures due deterioration and traumatic shock events. The main aim is to provide a model to assess the value of condition monitoring information for the maintenance decision-making. A condition-based periodic inspection/replacement policy is developed and compared with a benchmark time-based block replacement policy. Numerical results show that it is indeed useful to follow closely the actual evolution of the system to adapt the maintenance decisions to the true system state to improve the performance of maintenance policies. The analysis of the maintenance costs savings can be used to justify or not the choice to implement a policy based on condition monitoring information and to invest in condition monitoring devices.
Directory of Open Access Journals (Sweden)
G.S. Vorobyov
2014-04-01
Full Text Available The article describes the experimental equipment and the results of investigations of nonlinear processes occurring during the excitation of electromagnetic oscillations in the resonant electron beam devices such as an orotron-generator of diffraction radiation. These devices are finding wide application in physics and microwave technology, now. A technique for experimental research, which bases on the using of the universal electro vacuum equipment diffraction radiation analyzer and the microprocessor system for collecting and processing data. The experimental investigations results of the energy and frequency characteristics for the most common modes of the excitation oscillations in the open resonant systems such as an orotron. The implementations on the optimum modes for the oscillations excitation in such devices were recommended.
Limit cycles and quasi periodic post-critical behaviour of a two dimensional aeroelastic system.
Czech Academy of Sciences Publication Activity Database
Pospíšil, Stanislav; Náprstek, Ji?í
Southampton : University of Southampton, 2008 - (Brennan, M.), s. 58-69 ISBN 978-0-85432-882-6. [EURODYN 2008. Southampton (GB), 07.07.2008-09.07.2008] R&D Projects: GA ?R(CZ) GA103/05/2396 Institutional research plan: CEZ:AV0Z20710524 Keywords : aeroelastic system * limit cycles * instability * post -critical behaviour Subject RIV: JN - Civil Engineering
Johansson, Stefan
2009-01-01
Modern control theory is today an interdisciplinary area of research. Just as much as this can be problematic, it also provides a rich research environment where practice and theory meet. This Thesis is conducted in the borderline between computing science (numerical analysis) and applied control theory. The design and analysis of a modern control system is a complex problem that requires high qualitative software to accomplish. Ideally, such software should be based on robust methods and num...
The hematopoietic system of the acute radiation syndrome reconvalescents in post-accidental period
International Nuclear Information System (INIS)
The state of hemopoietic system has been studied since 1986 up to now in 145 patients who had acute radiation sickness after the Chernobyl accident. We studied clinical, morpho functional, histological, ultrastructural, biophysical, cultural, cytochemical indexes of the hematopoietic elements. The connection between hemopoietic microenvironment and hemopoiesis state was put up. The realization of the hematological disorders as myelodysplastic syndrome testified the most important problem in future
Real-time Scheduling of periodic tasks in a monoprocessor system with a rechargeable battery
Chetto, Maryline; El Ghor, Hussein
2009-01-01
We are interested in a real-time computing system that is powered through a rechargeable battery. In this context, two constraints need to be addressed: energy and deadlines. Classical task scheduling, in particular Earliest Deadline First, only accounts for timing parameters of the tasks and conse- quently is not suitable when considering energy constraints. We show here how to modify Earliest Deadline so as to account for the properties of the energy source, capacity of the energy storage a...
Health care system of the Republic of Serbia in the period 2004-2012
Gaji?-Stevanovi? Milena; Aleksi? Jovana; Stojanovi? Neda; Živkovi? Slavoljub
2014-01-01
Introduction. The backbone of Serbian health system forms the public healthcare provider network with 355 institutions and around 112,000 employees, owned and controlled by the Ministry of Health and financed mainly by the Republican Health Insurance Fund. The law recognizes private practice that was not included, till recently, in the public funding scheme. New Health Insurance Law (2005) decreased the number of entitlements in the basic health service pac...
VALUE ADDED TAX SYSTEM AND DYNAMICS OF RATE IN THE PERIOD OF EUROPEAN UNION CRISIS
Directory of Open Access Journals (Sweden)
Dovil? Kurtinaityt?-Venediktovien?
2013-06-01
Full Text Available Purpose - the article aims to assess the economic efficiency of value-added tax as the prime indirect tax. The analysis focuses on flaws of the current value-added tax system; ways to eliminate the flaws and make European Union-wide improvements in the system are discussed. In her research article, the author also presents the research of the value-added tax rate dynamics in the European Union and assessment of value-added tax rate changes in Lithuania and Great Britain during the crisis. Design/methodology/approach - descriptive method, analysis of scientific literature, statistical analysis of data, analytical method, mathematical analysis, analysis of legal instruments, and comparative analysis. Findings – the author focuses on current scientific debates on ways to improve the value-added tax system according to the European Commission. In her article, the author presents the research of value-added tax rate dynamics in the European Union and the significance of value-added tax for the European Union budget revenue. Research limitations/implications – in the next paper would be added the most recent data, now they do not exist. Practical implications – the paper presents the theoretical framework for further study of value-added tax in European Union as basic material for classroom use. Originality/Value – the author presents the research of value-added tax rate dynamics in the European Union during economic crisis. Keywords: value added tax, indirect tax, dynamics, rate, European Union, economic crisis. Research type: research paper.
International Nuclear Information System (INIS)
It is of utmost importance to have a computer code in order to analyze how different parameters (like test duration time) affect the unavailability of safety systems of nuclear. In this context, a study was performed in order to evaluate the model employed by the FRANTIC computer code, which performs detailed calculations on the contribution to the system unavailability originated by hardware failures, component tests and repairs, aiming at considering the influence of different test schemes on the system unavailability. It was shown, by means of the results attained that the numerical model used by the FRANTIC code and the analytical model proposed by APOSTOLAKIS and CHU (4) give unavailability values much similar when the component tests are supposed to be perfect. When a test is supposed to be imperfect (that is, when it may induce a test is supposed to be imperfect (that is, when it may induce a failure on the component being tested), the analytical model presents more conservative results. (author)
Raupach, Marc
2015-01-01
The development and first applications of a new periodic energy decomposition analysis (pEDA) scheme for extended systems based on the Kohn-Sham approach to density functional theory are described. The pEDA decomposes the binding energy between two fragments (e.g. the adsorption energy of a molecule on a surface) into several well-defined terms: preparation, electrostatic and dispersion interaction, Pauli repulsion and orbital relaxation energies. The pEDA presented here for an AO-based implementation can handle restricted and unrestricted fragments for 0D to 3D systems considering periodic boundary conditions with and without the determination of fragment occupations. For the latter case, reciprocal space sampling is enabled. The new method gives comparable results to established schemes for molecular systems and shows good convergence with respect to the basis set (TZ2P), the integration accuracy and k-space sampling. Four typical bonding scenarios for surface adsorbate complexes were chosen to highlight th...
Directory of Open Access Journals (Sweden)
G. STEFAN
2013-12-01
Full Text Available The techniques of carp culture are highly diversified, ranging from the extensive production in pond or open water with no fertilization or supplemental feeding to highly intensive systems in concrete tanks or cages. Among the different carp species, common carp is the best species reared in intensive monoculture, the others (Chinese and Indian carps being usually cultivated in polyculture (P. Kestemont, 1995. An experiment was conducted in inside recirculation system conditions to identify the technological performances on carp growth and survival at the Fishing and Aquaculture Department, Galati, during winter period (February, 2007 – March, 2007. The 1-year-old carp (Cyprinus carpio 4792g; 4594 g; 4561 g and 4525 g (total weight grew to 7384g; 7017g; 6924g and 7125 g in 44 days in aquarium 1, 2, 3 and 4, respectively. In all aquariums, the fish appeared healthy and no mortality was observed. Feed conversion efficiencies (FCE had similar values among all aquariums, the highest FCE being found in B4 aquarium with 1, 57 value. Water quality parameters were acceptable range for fish culture. Results show that the carp rearing during winter period in the inside recirculation system is a very good economic solution.
Mishra, Punyashloke
1998-12-01
This dissertation attempts to understand the complete process of instructional software design by looking closely at one iteration of the development of an educational computer program. FLiPS (Flexible Learning In the Periodic System) is a World Wide Web based multi-media hypertext for learning complex concepts in chemistry related to the periodic system of elements. The process of design begins with a theoretical argument for seeing the periodic system of elements as being a complex and ill-structured domain. A significant aspect of this argument is the introduction of certain non-standard representations of the periodic system and a demonstration of how these representations emphasize different aspects of the complex relationships between elements. The design of FLiPS is based on Cognitive Flexibility Theory---a cognitive theory that emphasizes the use of multiple representations for advanced learning in complex domains. A detailed analysis of the process of design of FLiPS is offered within the context of significant themes/perspectives on the design process. A significant part of the process of design is studying the manner in which different users interact and learn with FLiPS. Multiple means of data collection are used to understand the patterns of interaction and the cognitive processes of four students as they worked with FLiPS. This data is used to construct rich narrative profiles of the individual students: their backgrounds, beliefs, and process of working and learning. Analysis indicates that the importance of FLiPS as a learning tool seems to be dependent on the ontological and epistemological beliefs of the participants. This data is also used to generate recommendations for the further development of FLiPS. This dissertation argues that the design of technological artifacts such as educational software is a complex process involving a continuous dialogue between theory and practice; between constraints and tradeoffs; between designers and their materials; between designers and the users/learners. It is through this dialogue that the meaning and nature of the artifact is defined and understood. This project ties together issues of instructional technology that are often seen in isolation, and emphasizes the cyclic and contingent nature of educational software design.
Okuno, Yuta; Small, Michael; Gotoda, Hiroshi
2015-04-01
We have examined the dynamics of self-excited thermoacoustic instability in a fundamentally and practically important gas-turbine model combustion system on the basis of complex network approaches. We have incorporated sophisticated complex networks consisting of cycle networks and phase space networks, neither of which has been considered in the areas of combustion physics and science. Pseudo-periodicity and high-dimensionality exist in the dynamics of thermoacoustic instability, including the possible presence of a clear power-law distribution and small-world-like nature.
Jacobs, J.; Marshall, N.; Cockmartin, L.; Zanca, F.; van Engen, R.; Young, K.; Bosmans, H.; Samei, E.
2010-04-01
As a collaborative effort between scientists affiliated with the American Association of Physicists in Medicine (AAPM) and the European reference center for breast cancer screening and diagnosis (EUREF), the Working Group on Phantoms for Breast Imaging (WGPBI) aims to develop phantoms and evaluation techniques for 2D & 3D breast imaging modalities. In the first phase of this collaboration, this project aimed to develop a phantom and associated procedure for constancy testing of digital breast tomosynthesis (DBT) systems. The procedure involves daily and weekly components. The daily evaluation is performed on a simple, homogenous PMMA plate of 4 cm thickness. For the weekly part, a new phantom has been designed consisting of a 45 mm thick homogeneous slab of PMMA with a set of spherical and rectangular inserts at specific 3D positions, and a thin wire positioned at a small angle to the plane of the detector. Quality control parameters are extracted from both projection images (if available) and reconstructed planes. The homogeneous phantom for daily QC allows a trend analysis of homogeneity and the assessment of detector artifacts. With the proposed phantom concept for weekly QC, the stability of the following parameters can be evaluated: the propagation and correlation of the noise in plane and across the reconstructed tomographic planes, lag, signal difference to noise ratio (SDNR) and signal to noise ratio (SNR), the geometry and the motion, effective thickness of the reconstructed planes, homogeneity, distance accuracy, frequency dependent SNR, and artifacts. Analysis of the DICOM header provides information on the stability of the automatic exposure control (AEC), exposure settings, and several system parameters. In an on-going study, the proposed strategy is being applied to five tomosynthesis systems both in Europe and in the US. In this paper we report on the specifics of the phantom, the QC procedure, the practicalities of remote data analysis, and the results of the initial trial.
International Nuclear Information System (INIS)
The conceptual design of an on-line, near-real-time nondestructive assay instrumentation network for the Los Alamos Plutonium Facility is complete. Analysis of instrument history data indicates that the instrument certification procedures need improvement. Analysis of exhaust filter data has led to the derivation of a buildup prediction equation that is a function of throughput. This suggests that development of a generalized model is possible. A number of routine reports are now available from the Plutonium Facility/Los Alamos Safeguards System including inventories and active reports
Axonal wiring defects and critical period plasticity in the postnatal motor system
Helmbrecht, Michaela Sabine
2015-01-01
This thesis investigates the postnatal consequences of axon miswiring in the spinal motor system and mechanisms of plasticity that allow for their compensation. I showed that depletion of Npn1 from motor neurons causes severe postnatal defects due to loss of motor axons from the radial nerve. Defective Sema3A-Npn1 binding does not induce the same defects, suggesting that additional binding partners for Npn1 might allow for the compensation of these deficits. Furthermore, I introduced Sema3F m...
International Nuclear Information System (INIS)
Interfacial behavior of extractant molecules and their interaction with metal ions has been investigated. Consideration was also given to the question of microscopic interfaces, i.e., those associated with reversed micelles as well as microemulsions. NMR spectroscopy, fluorescence spectroscopy, quasi-elastic light scattering, vapor pressure osmometry, and Karl-Fischer titrimetry provided support for findings obtained from interfacial tension experiments that reversed micelles are formed, under certain conditions, in the system di(2-ethylhexyl)phosphoric acid (HDEHP)/ n-hexane/CaCl2 solution. These techniques were further extended to include different organophosphorus acids (PC 88A and CYANEX 272), diluent (benzene), and metal ions (Co2+, Ni2+, and Zn2+) to determine whether reversed micellization occurs in solvent extraction systems which employ organophosphorus acids. A preliminary general model of the aggregation mechanism for metal-extractant complexes has been proposed. Also various laser techniques have been used to investigate the structure and dynamics of extractant films. A laser fluorescence apparatus for probing interfacial dynamics is under construction. 64 refs., 29 figs
International Nuclear Information System (INIS)
A model identification methodology for periodical verification of the regulating system parameters at Cernavoda NPP Unit 1 was developed. As support to this methodology, the computer program MODELIDENT was implemented in the Java programming language. This program is used for off-line evaluation of the real regulating systems characteristic parameters using an identification algorithm which takes as input data the system response collected for different input excitation signals, a structurally similar model of the analyzed regulating system, and some starting guess value of the unknown parameters. The real values of the parameters are determined during MODELIDENT program execution by applying an iterative algorithm and afterwards are retained as nominal reference values. The success of the identification algorithm is strongly dependent on how appropriately the structure of model's transfer function is chosen. By repeating periodically the identification method, using newly collected data from the process, the current value of the parameters are determined. Any deviations of the new values relative to the nominal reference values are interpreted as de-calibration of the control equipment and in this case corrective maintenance actions have to be taken. With the implementation of the presented methodology at Cernavoda NPP Unit 1 we can make the statement that the preventive maintenance activity is gaining a predictive feature, which can lead to the elimination of major degradation possibilities in the performances of the RS equipment and consequently to increase the NPP availability. On the basis of the experience gained in the practical application of the presented methodology we expect that the identification method will also have beneficial effects in the optimal control of the process systems and also in the activity of Full Scope Simulator software maintenance (the reference values of the identified parameters being used for fine tuning of the simulation models. (authors)
Few period quasisymmetric stellarators
Energy Technology Data Exchange (ETDEWEB)
Isaev, M.Y.; Mikhailov, M.I.; Shafranov, V.D.; Subbotin, A.A. [Russian Research Centre `Kurchatov Institute`, Moscow (Russian Federation); Cooper, W.A. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP); Medvedev, S.Y. [Keldysh Inst. of Applied Mathematics, Russian Academy of Sciences, Moscow (Russian Federation)
1997-06-01
The results of plasma equilibrium and local stability investigations in two and four-period quasisymmetric stellarators are presented. A near-axis approximation is used for 2-period systems and the 3D codes VMEC and TERPSICHORE are used for four-periods devices to optimise the configurations. (author) 4 figs., 8 refs.
A Practical Approach to Improve Optical Channel Utilization Period for Hybrid FSO/RF Systems
Directory of Open Access Journals (Sweden)
Ahmet Akbulut
2014-01-01
Full Text Available In hybrid FSO/RF systems, mostly a hard switching mechanism is preferred in case of the FSO signal level falls below to the predefined threshold. In this work, a computationally simple approach is proposed to increase the utilization of the FSO channels bandwidth advantage. For the channel, clear air conditions have been supposed with the atmospheric turbulence. In this approach, FSO bit rate is adaptively changed to achieve desired BER performance. An IM/DD modulation, OOK (NRZ format has been used to show the benefit of the proposed method. Furthermore, to be more realistic with respect to the atmospheric turbulence variations within a day, some experimental observations have been followed up.
Mitral restenosis in the early postoperative period of a patient with systemic lupus erythematosus
Directory of Open Access Journals (Sweden)
Pomerantzeff Pablo Maria Alberto
1999-01-01
Full Text Available A forty eight year old woman, who had undergone mitral comissurotomy and subsequently developed early restenosis, presented with major comissural fusion and verrucous lesions on the cuspid edges of the mitral valve, with normal subvalvar apparatus. Patient did well for the first six months after surgery when she began to present dyspnea on light exertion. A clinical diagnosis of restenosis was made, which was confirmed by an echocardiogram and cardiac catheterization. She underwent surgery, and a stenotic mitral valve with verrucous lesions suggesting Libman-Sacks' endocarditis was found. Because the diagnosis of systemic lupus erythematosus (SLE had not been confirmed at that time, a bovine pericardium bioprosthesis (FISICS-INCOR was implanted. The patient did well in the late follow-up and is now in NYHA Class I .
1986-05-01
This interim final rule sets forth revisions to the Medicare inpatient hospital prospective payment system. This rule is needed to implement those portions of sections 9101 through 9105 and 9112 of the Consolidated Omnibus Budget Reconciliation Act of 1985 having an effective date of May 1, 1986 or earlier. The changes required by this legislation affect the fiscal year 1986 prospective payment rates; the rate-of-increase limits (target amounts) for hospitals excluded from the prospective payment system; the length of the transition period and the method of payment; application of the hospital wage index; payment for the indirect costs of medical education; and payments for hospitals that serve a disproportionate share of low-income patients. PMID:10300763
DEFF Research Database (Denmark)
Olsen, Bjarke Tobias; Smith Korsholm, Ulrik
2015-01-01
At the Danish Meteorological Institute, the NWP nowcasting system has been enhanced to include assimilation of 2D precipitation rates derived from weather radar observations. The assimilation is performed using a nudging-based technique. Here the rain rates are used to estimate the changes in the vertical profile of horizontal divergence needed to induce the observed rain rate. Verification of precipitation forecasts for a 17-day period in August 2010 based on the NWP nowcasting system is presented and compared to a reference without assimilation of precipitation data. In Denmark, this period was particularly rainy, with several heavy precipitation events. Three of these events are studied in detail. The verification is mainly based on scatter plots and fractions skill scores, which give scale-dependant indicators of the spatial skill of the forecasts. The study shows that the inclusion of precipitation observations has a positive impact on the spatial skill of the forecasts. This positive impact is the largest in the first hour, and then gradually decreases. On the average, the forecasts with assimilation of precipitation are skilful after 4 h on scales down to a few tens of kilometers. For the events studied, the assimilation improves the forecasted frequencies of heavy and light precipitation relative to the control, while there is some tendency to overpredict intermediate precipitation levels.
Li, Yongkun; Ye, Yuan
2013-11-01
In this paper, by using Mawhin's continuation theorem of coincidence degree theory, we study an impulsive non-autonomous Lotka-Volterra predator-prey system with harvesting terms and obtain some sufficient conditions for the existence of multiple positive almost periodic solutions for the system under consideration. Our results of this paper are completely new and our method used in this paper can be used to study the existence of multiple positive almost periodic solutions to other types of population systems.
Finite Elements for a Beam System With Nonlinear Contact Under Periodic Excitation
Hazim, Hamad
2009-01-01
Solar arrays are structures which are connected to satellites; during launch, they are in a folded position and submitted to high vibrations. In order to save mass, the flexibility of the panels is not negligible and they may strike each other; this may damage the structure. To prevent this, rubber snubbers are mounted at well chosen points of the structure; a prestress is applied to the snubber; but it is quite difficult to check the amount of prestress and the snubber may act only on one side; they will be modeled as one sided springs (see figure 2). In this article, some analysis for responses (displacements) in both time and frequency domains for a clamped-clamped Euler-Bernoulli beam model with a spring are presented. This spring can be unilateral or bilateral fixed at a point. The mounting (beam +spring) is fixed on a rigid support which has a sinusoidal motion of constant frequency. The system is also studied in the frequency domain by sweeping frequencies between two fixed values, in order to save the...
Multi-periodic pulsations of a stripped red-giant star in an eclipsing binary system
Maxted, Pierre F. L.; Serenelli, Aldo M.; Miglio, Andrea; Marsh, Thomas R.; Heber, Ulrich; Dhillon, Vikram S.; Littlefair, Stuart; Copperwheat, Chris; Smalley, Barry; Breedt, Elmé; Schaffenroth, Veronika
2013-06-01
Low-mass white-dwarf stars are the remnants of disrupted red-giant stars in binary millisecond pulsars and other exotic binary star systems. Some low-mass white dwarfs cool rapidly, whereas others stay bright for millions of years because of stable fusion in thick surface hydrogen layers. This dichotomy is not well understood, so the potential use of low-mass white dwarfs as independent clocks with which to test the spin-down ages of pulsars or as probes of the extreme environments in which low-mass white dwarfs form cannot fully be exploited. Here we report precise mass and radius measurements for the precursor to a low-mass white dwarf. We find that only models in which this disrupted red-giant star has a thick hydrogen envelope can match the strong constraints provided by our data. Very cool low-mass white dwarfs must therefore have lost their thick hydrogen envelopes by irradiation from pulsar companions or by episodes of unstable hydrogen fusion (shell flashes). We also find that this low-mass white-dwarf precursor is a type of pulsating star not hitherto seen. The observed pulsation frequencies are sensitive to internal processes that determine whether this star will undergo shell flashes.
Existence of lattice solutions to semilinear elliptic systems with periodic potential
Directory of Open Access Journals (Sweden)
Nicholas D. Alikakos
2012-01-01
Full Text Available Under the assumption that the potential W is invariant under a general discrete reflection group $G'=TG$ acting on $mathbb{R}^n$, we establish existence of G'-equivariant solutions to $Delta u - W_u(u = 0$, and find an estimate. By taking the size of the cell of the lattice in space domain to infinity, we obtain that these solutions converge to G-equivariant solutions connecting the minima of the potential W along certain directions at infinity. When particularized to the nonlinear harmonic oscillator $u''+alpha sin u=0$, $alpha>0$, the solutions correspond to those in the phase plane above and below the heteroclinic connections, while the G-equivariant solutions captured in the limit correspond to the heteroclinic connections themselves. Our main tool is the G'-positivity of the parabolic semigroup associated with the elliptic system which requires only the hypothesis of symmetry for W. The constructed solutions are positive in the sense that as maps from $mathbb{R}^n$ into itself leave the closure of the fundamental alcove (region invariant.
Kang-Kang, Wang; Xian-Bin, Liu; Yu, Zhou
2015-08-01
In this paper, the stability and stochastic resonance (SR) phenomenon induced by the multiplicative periodic signal for a metapopulation system driven by the additive Gaussian noise, multiplicative non-Gaussian noise and noise correlation time is investigated. By using the fast descent method, unified colored noise approximation and McNamara and Wiesenfeld’s SR theory, the analytical expressions of the stationary probability distribution function and signal-to-noise ratio (SNR) are derived in the adiabatic limit. Via numerical calculations, each effect of the addictive noise intensity, the multiplicative noise intensity and the correlation time upon the steady state probability distribution function and the SNR is discussed, respectively. It is shown that multiplicative, additive noises and the departure parameter from the Gaussian noise can all destroy the stability of the population system. However, the noise correlation time can consolidate the stability of the system. On the other hand, the correlation time always plays an important role in motivating the SR and enhancing the SNR. Under different parameter conditions of the system, the multiplicative, additive noises and the departure parameter can not only excite SR phenomenon, but also restrain the SR phenomenon, which demonstrates the complexity of different noises upon the nonlinear system.
Occupational external irradiation according to the control system data for the period 1984-1988
International Nuclear Information System (INIS)
The dose load to subjects working with radiation sources in Bulgaria was analysed on the basis of data obtained from the Centralized System for Individual Dosimetric Control. Personnel film- and thermoluminenscent dosimetry had been used for monitoring of about 8000 persons including 66% medical personnel (54% of them practicians, 12% - researchers), 28% industrial personnel, 6% - working in the science/education sphere. The external irradiation is prevailing. The average annual equivalent doses (AAED) by branches were: medicine 0.6 - 0.9 mSv/a, industry 1.3 - 3.1 mSCv/a, science/education 1.0 - 1.2 mSv/a. The most badly loaded contingent (? 5 mSv/a) were the gamma-defectoscopists, which represent one third of the group of industrial workers. The irradiation levels in X-ray and radioisotope diagnosis are low. Similar are also the conclusions derived from the comparison of the weighted average annual equivalent doses (WAAED): medicine 0.85 mSv/a; industry 2.3 mSv/a; science/education 1.1 mSv/a. Higher than the average one for respective areas is the irradiation in gamma-defectoscopy, radiotherapy and services for electromedical equipment. The WAAED for the contingent in this study was 1.3 mSv/a, and 95% of AAED received were lower than 5 mSv/a. The low probability of irradiation with doses higher than 50 mSv/a in medicine and industry was established. 2 tabs., 2 figs., 6 refs
Investigation of periodic multilayers
Bodnarchuck, V; Ignatovich, V; Veres, T; Yaradaykin, S
2009-01-01
Periodic multilayers of various periods were prepared according to an algorithm proposed by the authors. The reflectivity properties of these systems were investigated using neutron reflectometry.The obtained experimental results were compared with the theoretical expectations. In first approximation, the results proved the main features of the theoretical predictions. These promising results initiate further research of such systems.
DEFF Research Database (Denmark)
Marzband, Mousa; Azarinejadian, Fatemeh
2015-01-01
Optimal operation programming of electrical systems through minimization of production cost and market clearing price (MCP) as well as better utilization of renewable energy resources has attracted the attention of many researchers. To reach this aim, energy management systems (EMS) has been studied in many research activities. Moreover, demand response (DR) expands customer participation to power systems and results in a paradigm shift from conventional to interactive activities in power systems due to the progress of smart grid technology. Therefore, modelling of consumer characteristic in DR is becoming so important issues in these systems. The customer information as the registration and participation information of DR is used to provide additional indices for evaluating customer response, such as consumer0s information based on the offer priority, DR magnitude, duration, and minimum cost of energy (COE). In this paper, a multi-period artificial bee colony (MABC) optimization algorithm is implemented for economic dispatch considering generation, storage and responsive load offers. The better performance of the proposed algorithm is shown in comparison with the modified conventional energy management system (MCEMS) and its effectiveness is validated experimentally over a Microgrid (MG) Testbed. The obtained results show cost reduction (by around 30%), convergence speed increase as well as remarkable improvement of efficiency and accuracy under uncertain conditions. An artificial neural network (ANN) combined with Markov-chain (MC) (ANN-MC) approach is used to predict non-dispatchable power generation and load demand considering uncertainties. Furthermore, other capabilities such as extendibility, reliability and flexibility are examined about the proposed approach.
Variability of the Spin Period of the White Dwarf in the Magnetic Cataclysmic Binary System EX Hya
Andronov, Ivan L
2013-01-01
The observations of the two-periodic magnetic cataclysmic system EX Hya have been carried out, using the telescopes RC16 and TOA-150 of the Tzec Maun observatory. 6 nights of observations were obtained in 2010-2011 (alternatively changing filters VR). Also the databases of WASP, ASAS and AAVSO have been analyzed. Processing time series was carried out using the program MCV. We analyzed changes in the rotation period of the white dwarf, and based on our own and previously published moments of maximum. The ephemeris was determined for the maxima of the radiation flux associated with the rotation of the magnetic white dwarf: Tmax=2437699.89079(59) +0.0465464808(69).E-6.3(2)*10^{-13}E^2, which corresponds to the characteristic timescale of the rotation spin-up of 4.67(14)*10^6 years. This contradicts the estimated value of the mass of the white dwarf of 0.42M_\\odot, based on X-ray observations made by Yuasa et al (2010), however, is consistent with estimates of the masses of 0.79 M_\\odot (white dwarf) and 0.108 M...
Lin, Shou-Tai; Hsieh, Chuan-Sheng
2012-12-31
This study presents a diode-pumped cw triple-wavelength Nd:GdVO? laser system using an electro-optic periodically poled lithium niobate (PPLN) Bragg modulator. The PPLN consists of two cascaded sections, 20.3 ?m and 25.7 ?m, functioning as loss modulators for 1063 and 1342 nm at the same Bragg incident angle. When switching the dc voltages on PPLN and applying 25 W pump power, the output wavelength can be selected among 912, 1063, and 1342 nm with output power of 2, 5, and 1.4 W, respectively. The device is capable of triple-wavelength generation simultaneous when applied voltages are 180 (? = 20.3 ?m) and -50 V (? = 25.7 ?m) at a 25 W pump power. Gain competition induced power instability was also observed. PMID:23388793
Levchenko, Sergey V.; Ren, Xinguo; Wieferink, Jürgen; Johanni, Rainer; Rinke, Patrick; Blum, Volker; Scheffler, Matthias
2015-07-01
We describe a framework to evaluate the Hartree-Fock exchange operator for periodic electronic-structure calculations based on general, localized atom-centered basis functions. The functionality is demonstrated by hybrid-functional calculations of properties for several semiconductors. In our implementation of the Fock operator, the Coulomb potential is treated either in reciprocal space or in real space, where the sparsity of the density matrix can be exploited for computational efficiency. Computational aspects, such as the rigorous avoidance of on-the-fly disk storage, and a load-balanced parallel implementation, are also discussed. We demonstrate linear scaling of our implementation with system size by calculating the electronic structure of a bulk semiconductor (GaAs) with up to 1,024 atoms per unit cell without compromising the accuracy.
International Nuclear Information System (INIS)
This work analyzes numerically the effects of delay time ? and cross-correlation strength between noises ? on the phenomena of noise enhanced stability (NES) and resonant activation (RA) in a periodically modulated bistable system. The simulation results indicate that: (i) multiplicative noise can produce the NES effect only for the larger ?, while additive noise always induces the NES effect; (ii) for the NES phenomenon induced by additive noise, there is a characteristic value of ?, below which the increasing of ? enhances it and above which the effect of ? reverses; however, the increasing of ? can only enhance the NES effect induced by multiplicative noise; (iii) increasing ? weakens the NES effect induced by additive noise and strengthens that induced by multiplicative noise; and (iv) the RA effect becomes more and more pronounced while the RA minimum of the mean first-passage time increases with the increase of ? or ?. (paper)
Searches for periodic neutrino emission from binary systems with 22 and 40 strings of IceCube
Abbasi, R; Abu-Zayyad, T; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Allen, M M; Altmann, D; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Bay, R; Alba, J L Bazo; Beattie, K; Beatty, J J; Bechet, S; Becker, J K; Becker, K -H; Benabderrahmane, M L; BenZvi, S; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bose, D; Böser, S; Botner, O; Brown, A M; Buitink, S; Caballero-Mora, K S; Carson, M; Chirkin, D; Christy, B; Clevermann, F; Cohen, S; Colnard, C; Cowen, D F; Silva, A H Cruz; D'Agostino, M V; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; Degner, T; Demirörs, L; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; Díaz-Vélez, J C; Dierckxsens, M; Dreyer, J; Dumm, J P; Dunkman, M; Eisch, J; Ellsworth, R W; Engdegård, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Fox, B D; Franckowiak, A; Franke, R; Gaisser, T K; Gallagher, J; Gerhardt, L; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Goodman, J A; Góra, D; Grant, D; Griesel, T; Groß, A; Grullon, S; Gurtner, M; Ha, C; Ismail, A Haj; Hallgren, A; Halzen, F; Han, K; Hanson, K; Heinen, D; Helbing, K; Hellauer, R; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, B; Homeier, A; Hoshina, K; Huelsnitz, W; Hülß, J -P; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Japaridze, G S; Johansson, H; Kampert, K -H; Kappes, A; Karg, T; Karle, A; Kenny, P; Kiryluk, J; Kislat, F; Klein, S R; Köhne, J -H; Kohnen, G; Kolanoski, H; Köpke, L; Kopper, S; Koskinen, D J; Kowalski, M; Kowarik, T; Krasberg, M; Kroll, G; Kurahashi, N; Kuwabara, T; Labare, M; Laihem, K; Landsman, H; Larson, M J; Lauer, R; Lünemann, J; Madsen, J; Marotta, A; Maruyama, R; Mase, K; Matis, H S; Meagher, K; Merck, M; Mészáros, P; Meures, T; Miarecki, S; Middell, E; Milke, N; Miller, J; Montaruli, T; Morse, R; Movit, S M; Nahnhauer, R; Nam, J W; Naumann, U; Nygren, D R; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Panknin, S; Paul, L; Heros, C Pérez de los; Petrovic, J; Piegsa, A; Pieloth, D; Porrata, R; Posselt, J; Price, P B; Przybylski, G T; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Richman, M; Rodrigues, J P; Rothmaier, F; Rott, C; Ruhe, T; Rutledge, D; Ruzybayev, B; Ryckbosch, D; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Schmidt, T; Schönwald, A; Schukraft, A; Schultes, A; Schulz, O; Schunck, M; Seckel, D; Semburg, B; Seo, S H; Sestayo, Y; Seunarine, S; Silvestri, A; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stezelberger, T; Stokstad, R G; Stößl, A; Strahler, E A; Ström, R; Stüer, M; Sullivan, G W; Swillens, Q; Taavola, H; Taboada, I; Tamburro, A; Tepe, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Tosi, D; van Eijndhoven, N; Vandenbroucke, J; Van Overloop, A; van Santen, J; Vehring, M; Voge, M; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Weaver, Ch; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wischnewski, R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, C; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Zoll, M
2011-01-01
Recent observations of GeV/TeV photon emission from several X-ray binaries have sparked a renewed interest in these objects as galactic particle accelerators. In spite of the available multi-wavelength data, their acceleration mechanisms are not determined, and the nature of the accelerated particles (hadrons or leptons) is unknown. While much evidence favors leptonic emission, it is very likely that a hadronic component is also accelerated in the jets of these binary systems. The observation of neutrino emission would be clear evidence for the presence of a hadronic component in the outflow of these sources. In this paper we look for periodic neutrino emission from binary systems. Such modulation, observed in the photon flux, would be caused by the geometry of these systems. The results of two searches are presented that differ in the treatment of the spectral shape and phase of the emission. The 'generic' search allows parameters to vary freely and best fit values, in a 'model-dependent' search, predictions...
IUPAC Periodic Table of Isotopes for the Educational Community
Energy Technology Data Exchange (ETDEWEB)
Holden N. E.; Holden,N.E.; Coplen,T.B.
2012-07-15
John Dalton first proposed the concept of atomic weights of the elements in the first decade of the nineteenth century. These atomic weights of the chemical elements were thought of as constants of nature, similar to the speed of light. Dmitri Mendeleev arranged the atomic weights of the elements in ascending order of value and used the systematic variation of their chemical properties to produce his Periodic Table of the Elements in 1869. Measurement of atomic weight values became an important chemical activity for a century and a half. Theodore Richards received a Noble Prize for his work in this area. In 1913, Fredrick Soddy found a species of radium, which had an atomic weight value of 228, compared to the familiar radium gas value of 226. Soddy coined the term 'isotope' (Greek for 'in the same place') to account for this second atomic weight value in the radium position of the Periodic Table. Both of these isotopes of radium are radioactive. Radioactive isotopes are energetically unstable and will decay (disintegrate) over time. The time it takes for one half of a sample of a given radioactive isotope to decay is the half-life of that isotope. In addition to having different atomic weight values, radium-226 and radium-228 also have different half-life values. Around the same time as Soddy's work, J.J. Thomson (discoverer of the electron) identified two stable (non-radioactive) isotopes of the same element, neon. Over the next 40 years, the majority of the known chemical elements were found to have two or more stable (or long-lived radioactive isotopes that contribute significantly to the determination of the atomic weights of the elements).
IUPAC Periodic Table of Isotopes for the Educational Community
International Nuclear Information System (INIS)
John Dalton first proposed the concept of atomic weights of the elements in the first decade of the nineteenth century. These atomic weights of the chemical elements were thought of as constants of nature, similar to the speed of light. Dmitri Mendeleev arranged the atomic weights of the elements in ascending order of value and used the systematic variation of their chemical properties to produce his Periodic Table of the Elements in 1869. Measurement of atomic weight values became an important chemical activity for a century and a half. Theodore Richards received a Noble Prize for his work in this area. In 1913, Fredrick Soddy found a species of radium, which had an atomic weight value of 228, compared to the familiar radium gas value of 226. Soddy coined the term 'isotope' (Greek for 'in the same place') to account for this second atomic weight value in the radium position of the Periodic Table. Both of these isotopes of radium are radioactive. Radioactive isotopes are energetically unstable and will decay (disintegrate) over time. The time it takes for one half of a sample of a given radioactive isotope to decay is the half-life of that isotope. In addition to having different atomic weight values, radium-226 and radium-228 also have different half-life values. Around the same time as Soddy's work, J.J. Thomson (discoverer of the electron) identified two stable (non-radioactive) isotopes of the same element, neon. Over the next 40 years, the majority of the known cnext 40 years, the majority of the known chemical elements were found to have two or more stable (or long-lived radioactive isotopes that contribute significantly to the determination of the atomic weights of the elements).
International Nuclear Information System (INIS)
In this paper, we study two species predator-prey Lotka-Volterra type dispersal system with periodic coefficients, in which the prey species can disperse among n patches, while the density-independent predator species is confined to one of the patches and cannot disperse. Sufficient conditions on the boundedness, permanence and existence of positive periodic solution for this system are established. The theoretical results are confirmed by a special example and numerical simulations
Energy Technology Data Exchange (ETDEWEB)
Zhang Long [College of Mathematics and System Sciences, Xinjiang University, Urumqi 830046 (China)], E-mail: longzhang_xj@sohu.com; Teng Zhidong [College of Mathematics and System Sciences, Xinjiang University, Urumqi 830046 (China)], E-mail: zhidong@xju.edu.cn
2008-05-15
In this paper, we study two species predator-prey Lotka-Volterra type dispersal system with periodic coefficients, in which the prey species can disperse among n patches, while the density-independent predator species is confined to one of the patches and cannot disperse. Sufficient conditions on the boundedness, permanence and existence of positive periodic solution for this system are established. The theoretical results are confirmed by a special example and numerical simulations.
... Date reviewed: October 2013 Back 1 ? 2 For Teens For Kids For Parents MORE ON THIS TOPIC Gyn Checkups I'm 14 and I Don't Have My Period Yet. Is This Normal? Can a Girl Get Pregnant if She Has Sex During Her Period? Birth Control Pill Coping With ...
Searches for Periodic Neutrino Emission from Binary Systems with 22 and 40 Strings of IceCube
Abassi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; BenZvi, S.; Berdermann, J.; Berghaus, P.
2011-01-01
Recent observations of GeV /TeV photon emission from several X-ray binaries have sparked a renewed interest in these objects as galactic particle accelerators. In spite of the available multi-wavelength data, their acceleration mechanisms are not determined, and the nature of the accelerated particles (hadrons or leptons) is unknown. While much evidence favors leptonic emission, it is very likely that a hadronic component is also accelerated in the jets of these binary systems. The observation of neutrino emission would be clear evidence for the presence of a hadronic component in the outflow of these sources. In this paper we look for periodic neutrino emission from binary systems. Such modulation, observed in the photon flux, would be caused by the geometry of these systems. The results of two searches are presented that differ in the treatment of the spectral shape and phase of the emission. The 'generic' search allows parameters to vary freely and best fit values, in a 'model-dependent' search, predictions are used to constrain these parameters. We use the IceCube data taken from May 31, 2007 to April 5, 2008 with its 22-string configuration, and from April 5, 2008 and May 20, 2009 with its 40-string configuration. For the generic search and the 40 string sample, we find that the most significant source in the catalog of 7 binary stars is Cygnus X-3 with a 1.8% probability after trials (2.10" sigma one-sided) of being produced by statistical fluctuations of the background. The model-dependent method tested a range of system geometries - the inclination and the massive star's disk size - for LS I+61 deg 303, no significant excess was found.
International Nuclear Information System (INIS)
VII All-Russian conference of young scientists, postgraduate students and students with international participation on chemistry and nanomaterials was conducted on the Chemistry department of Saint-Petersburg State University on April, 2-5, 2013. In the conference participants from 14 countries took part. There were five sections: Nanochemistry and nanomaterials, Analytic chemistry, Inorganic chemistry, Organic chemistry, Physical chemistry. In the collection (Section 5 - Physical chemistry) there are abstracts concerning the investigations of physico-chemical properties and structure of various materials: composites on the base of polymers and fullerenes, as well as catalysts, ion-exchange membranes, sorbents etc.; phase studies of different systems, rare earth elements among them; development of physico-chemical determination methods of biological active compounds, and many other problems
Shah, Shrenik
2013-01-01
We study the interpolation of Hodge-Tate and de Rham periods in families of Galois representations. Given a Galois representation on a coherent locally free sheaf over a reduced rigid space and a bounded range of weights, we obtain a stratification of this space by locally closed subvarieties where the Hodge-Tate and bounded de Rham periods (within this range) form locally free sheaves. At every thickened geometric point within one of the strata, we obtain a corresponding nu...
International Nuclear Information System (INIS)
The distribution of mercury contamination in the Santos - Sao Vicente Estuarine System was observed through the analysis of seventy seven surface sediments samples collected in two series. In different periods and points, since the Channel of Piacaguera, the head of the system, , through the estuarine arms of Santos and Sao Vicente as far as the Bay of Santos, about 30 Km downstream, and in different mangrove areas, including industrial and harbor influence zones. The obtained values ranged from 0.03 to 1.19 ?g g -1 About 90% of the samples of the first series collected among 1997-1998 and 50% of the second series collected among 1999-2000 presented levels of Hg > 0,13 ?g g -1 ,limit considered by the Canadian legislation and adopted by CETESB, below which doesn't happen adverse effect in the biological community. And about 35% of samples of the first series and 11 % of the second series presented concentrations of Hg > 0.698 ?g g -1 probable level of occurrence of adverse effect in the biological community. These results indicate an increase of the mercury levels caused by the industrial, port and urban activities. The mercury concentration in sediments was determined by using an Atomic Absorption Spectrophotometer, coupling with a flow injection system by a cold vapor generation, using a manual injection valve (FIA-CVAAS). The estimate of the uncertainties associated to this procedure was calculated. The following elements were also determined: Fe, Al, Zn, Ni, Pb, Cd, Cr and Co in 46 samples of the second series, by atomic absorption spectrometry. In order to verify possible relationship among all the investigated elements in the samples sediments, was carried out a statistical study, using the SPSS-8.0 software. Pearson correlation and Principal Component's analysis were used for with the objective to identify of major relationship for additional exploration of the general behavior of the data. (author)
El Aroudi A.
2014-01-01
In this paper closed-form conditions for predicting the boundary of period-doubling (PD) bifurcation or saddle-node (SN) bifurcation in a class of PWM piecewise linear systems are obtained from a time-domain asymptotic approach. Examples of switched system considered in this study are switching dc-dc power electronics converters, temperature control systems and hydraulic valve control systems among others. These conditions are obtained from the steady-state discrete-time model using an asympt...
International Nuclear Information System (INIS)
The proposed device for measuring the reactor period is in fact pulse system with variable sampling frequency. All the operations are pulse operation but in analog form and the variation of sampling frequency is automated. Analysis of errors due to statistical fluctuations showed that this system is self adaptive. Time constant of the linear input circuit enables sufficient attenuation of transients in the reactor and measuring the stable period without overflow in stationary state. The analysis of the system showed a series of advantages compared to the existing devices. Modern semiconductor technique was used in constructing the proposed period meter which enable high reliability
Gopalswamy, Nat; Yan, Yihua
2015-01-01
This paper presents an overview of results obtained during the CAWSES II period on the short term variability of the Sun and how it affects the near Earth space environment. CAWSES II was planned to examine the behavior of the solar terrestrial system as the solar activity climbed to its maximum phase in solar cycle 24. After a deep minimum following cycle 23, the Sun climbed to a very weak maximum in terms of the sunspot number in cycle 24 (MiniMax24), so many of the results presented here refer to this weak activity in comparison with cycle 23. The short term variability that has immediate consequence to Earth and geospace manifests as solar eruptions from closed field regions and high speed streams from coronal holes. Both electromagnetic (flares) and mass emissions (coronal mass ejections, CMEs) are involved in solar eruptions, while coronal holes result in high speed streams that collide with slow wind forming the so called corotating interaction regions (CIRs). Fast CMEs affect Earth via leading shocks ...
Energy Technology Data Exchange (ETDEWEB)
Funakoshi, Satoshi; Sato, Tomoyoshi; Miyazaki, Takeshi, E-mail: funakosi@miyazaki.mce.uec.ac.jp, E-mail: miyazaki@mce.uec.ac.jp [Department of Mechanical Engineering and Intelligent Systems, University of Electro-Communications, 1-5-1, Chofugaoka, Chofu, Tokyo 182-8585 (Japan)
2012-06-01
We investigate the statistical mechanics of quasi-geostrophic point vortices of mixed sign (bi-disperse system) numerically and theoretically. Direct numerical simulations under periodic boundary conditions are performed using a fast special-purpose computer for molecular dynamics (GRAPE-DR). Clustering of point vortices of like sign is observed and two-dimensional (2D) equilibrium states are formed. It is shown that they are the solutions of the 2D mean-field equation, i.e. the sinh-Poisson equation. The sinh-Poisson equation is generalized to study the 3D nature of the equilibrium states, and a new mean-field equation with the 3D Laplace operator is derived based on the maximum entropy theory. 3D solutions are obtained at very low energy level. These solution branches, however, cannot be traced up to the higher energy level at which the direct numerical simulations are performed, and transitions to 2D solution branches take place when the energy is increased. (paper)
Kobelková, Alena; Závodská, Radka; Sauman, Ivo; Bazalová, Olga; Dolezel, David
2015-04-01
Homologous circadian genes are found in all insect clocks, but their contribution to species-specific circadian timing systems differs. The aim of this study was to extend research within Lepidoptera to gain a better understanding of the molecular mechanism underlying circadian clock plasticity and evolution. The Mediterranean flour moth, Ephestia kuehniella (Pyralidae), represents a phylogenetically ancestral lepidopteran species. We have identified circadian rhythms in egg hatching, adult emergence, and adult locomotor activity. Cloning full-length complementary DNAs and further characterization confirmed one copy of period and timeless genes in both sexes. Both per and tim transcripts oscillate in their abundance in E. kuehniella heads under light-dark conditions. PER-like immunoreactivity (PER-lir) was observed in nuclei and cytoplasm of most neurons in the central brain, the ventral part of subesophageal complex, the neurohemal organs, the optic lobes, and eyes. PER-lir in photoreceptor nuclei oscillated during the day with maximal intensity in the light phase of the photoperiodic regime and lack of a signal in the middle of the dark phase. Expression patterns of per and tim messenger RNAs (mRNAs) were revealed in the identical location as the PER-lir was detected. In the photoreceptors, a daily rhythm in the intensity of expression of both per mRNA and tim mRNA was found. These findings suggest E. kuehniella as a potential lepidopteran model for circadian studies. PMID:25637625
International Nuclear Information System (INIS)
We investigate the statistical mechanics of quasi-geostrophic point vortices of mixed sign (bi-disperse system) numerically and theoretically. Direct numerical simulations under periodic boundary conditions are performed using a fast special-purpose computer for molecular dynamics (GRAPE-DR). Clustering of point vortices of like sign is observed and two-dimensional (2D) equilibrium states are formed. It is shown that they are the solutions of the 2D mean-field equation, i.e. the sinh-Poisson equation. The sinh-Poisson equation is generalized to study the 3D nature of the equilibrium states, and a new mean-field equation with the 3D Laplace operator is derived based on the maximum entropy theory. 3D solutions are obtained at very low energy level. These solution branches, however, cannot be traced up to the higher energy level at which the direct numerical simulations are performed, and transitions to 2D solution branches take place when the energy is increased. (paper)
Eleftherios Giovanis
2012-01-01
In this study two approaches are applied for the prediction of the economic recession or expansion periods in USA. The first approach includes Logit and Probit models and the second is an Adaptive Neuro-Fuzzy Inference System (ANFIS) with Gaussian and Generalized Bell membership functions. The in-sample period 1950-2006 is examined and the forecasting performance of the two approaches is evaluated during the out-of sample period 2007-2010. The estimation results show that the ANFIS model outp...
Jiang, Kejian; Zhu, Changsheng
2011-05-01
A method for multi-frequency periodic vibration suppressing in active magnetic bearing (AMB)-rotor systems is proposed, which is based on an adaptive finite-duration impulse response (FIR) filter in time domain. Firstly, the theoretic feasibility of the method is proved. However, two problems would be unavoidable, if the conventional adaptive FIR filter is adopted in practical application. One is that the convergence rate of the different frequency components may be highly disparate in multi-frequency vibration control. The other is that the computational complexity is significantly increased because the long memory FIR filter is required to match the transient response time of the AMB-rotor system. To overcome the problems above, the Fast Block Least Mean Square (FBLMS) algorithm is adopted to efficiently implement the computation in frequency domain at a computational cost far less than that of the conventional FIR filter. By the FBLMS algorithm, regardless of the number of the considered frequency components in vibration disturbance, the computational complexity would be invariable. Moreover, filter's weights in the FBLMS algorithm have the intuitional relation with signal's frequency. As a result, the convergence rate of each frequency component can be adjusted by assigning the individual step size parameter for each weight. Experiments with the reciprocating simulating disturbance test and the rotating harmonic vibration test were carried out on an AMB-rigid rotor test rig with a vertical shaft. The experiment results indicate that the proposed method with the FBLMS algorithm can achieve the good effectiveness for suppressing the multi-frequency vibration. The convergence property of each frequency component can be adjusted conveniently. Each harmonic component of the vibration can be addressed, respectively, by reconfiguring the frequency components of the reference input signal.
In this activity, students learn to recognize periodicity within a set of data by using the examples of pendulums and binary star systems. Included are prerequisites, enrichment activities, materials lists, datasets, instructions, and links to additional information..
International Nuclear Information System (INIS)
The primary emphasis during this time period was on documenting and improving fluctuation measurements with the heavy ion beam probe, improving the instrumentation and hardware and evaluating the requirements for scaling beam probes to reactor size confinement devices. All of the work has been reported in periodic progress reports and only a brief summary will be given here. 13 refs
2010-01-01
This unique periodic table presents the elements in an interesting visual display. Select an element, and find an image of the element, a description, history, and even an animation. Other chemical data is linked as a PDF file (requires Acrobat Reader).
International Nuclear Information System (INIS)
Thermo convective instabilities in horizontal fluid layers are discussed with emphasis on the Rayleigh-Bernard model problem. Steady solutions and time-dependent phenomena (relaxation oscillations and transition to turbulence) are studied within the nonlinear Boussinesq-Oberbeck approximation. Homogeneous steady solutions, limit cycles, and inhomogeneous (ordered) spatial structures are also studied in simple reaction-diffusion systems. Lastly, the non-periodic attractor that appears at large Rayleigh numbers in the truncated Boussinesq-Oberbeck model of Lorenz, is constructed, and a discussion of turbulent behavior is given. (Author) 105 refs
International Nuclear Information System (INIS)
By using cut flower culture method, effects of ?-ray radiation on mutant induction of fertilization period flower of the colza were investigated. Defining a seed formed after irradiation to M1, for M2 generation obtained by once and M3 generation obtained twice autophagy thereafter, systems different morphologically from its original kind were checked. As a result, it was confirmed that a system with rounded leaves, a system with spotted leaves, a system with fat end of pod, a system with deformed shape of pod, and so forth were found and mutant induction of radiation using cut flower culture was effective. (G.K.)
Directory of Open Access Journals (Sweden)
Dennis Nemzer
1989-09-01
Full Text Available A class of generalized functions, called periodic Boehmians, on the unit circle, is studied. It is shown that the class of Boehmians contain all Beurling distributions. An example of a hyperfunctlon that is not a Boehmian is given. Some growth conditions on the Fourier coefficients of a Boehmian are given. It is shown that the Boehmians, with a given complete metric topological vector space topology, is not locally bounded.
Energy Technology Data Exchange (ETDEWEB)
Khalaquzzaman, M.; Kang, Hyun Gook [Nuclear and Quantum Engineering Department, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Kim, Man Cheol [Integrated Safety Assessment Team, Korea Atomic Energy Research Institute, P.O. Box 1045, Yuseong, Daejeon 305-353 (Korea, Republic of); Seong, Poong Hyun, E-mail: phseong@kaist.ac.k [Nuclear and Quantum Engineering Department, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)
2011-05-15
Research highlights: Risk, cost, and public risk perception are incorporated to optimize test frequency. Protection system unavailability decreases with an increasing test frequency. CDF and spurious trip rate increase with human errors. Shorter interval tests are notably beneficial when the human error level is very low. Test error, moderator temperature coefficient, trip cost are key factors. - Abstract: Techniques for optimizing the frequency of periodic surveillance testing of nuclear power plant (NPP) safety systems have been receiving increased attention and growing importance because of the need to reduce system unavailability and maintenance cost. Economic losses from maintenance human errors should be included in estimating periodic testing and maintenance costs because the losses increase with maintenance human errors. This paper proposes a method for optimizing periodic testing intervals of a digital reactor protection system by balancing risk and cost of periodic surveillance tests, in which maintenance human error and public risk perception have been reflected. The risk and costs were estimated from both plant operator and socio-economic standpoints. This model determines the optimal testing frequency for the minimum value of an objective function that consists of all costs, including the monetary values of the consequence of maintenance human errors and reactor core damage. We present a case study using our model for the OPR1000 plant. The study results show the significance of reducing human errors in periodic testing and maintenance. The proposed method is expected to be useful to NPP operators as well as regulators for evaluating the optimal periodic testing frequency of a nuclear reactor protection system and for obtaining information needed in decision making processes.
International Nuclear Information System (INIS)
We present an update to seven stars with long-period planets or planetary candidates using new and archival radial velocities from Keck-HIRES and literature velocities from other telescopes. Our updated analysis better constrains orbital parameters for these planets, four of which are known multi-planet systems. HD 24040 b and HD 183263 c are super-Jupiters with circular orbits and periods longer than 8 yr. We present a previously unseen linear trend in the residuals of HD 66428 indicative of an additional planetary companion. We confirm that GJ 849 is a multi-planet system and find a good orbital solution for the c component: it is a 1 M Jup planet in a 15 yr orbit (the longest known for a planet orbiting an M dwarf). We update the HD 74156 double-planet system. We also announce the detection of HD 145934 b, a 2 M Jup planet in a 7.5 yr orbit around a giant star. Two of our stars, HD 187123 and HD 217107, at present host the only known examples of systems comprising a hot Jupiter and a planet with a well constrained period greater than 5 yr, and with no evidence of giant planets in between. Our enlargement and improvement of long-period planet parameters will aid future analysis of origins, diversity, and evolution of planetary systems
Energy Technology Data Exchange (ETDEWEB)
Katherina Feng, Y.; Wright, Jason T.; Nelson, Benjamin; Wang, Sharon X.; Ford, Eric B. [Center for Exoplanets and Habitable Worlds, Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Marcy, Geoffrey W.; Isaacson, Howard [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Howard, Andrew W., E-mail: astrowright@gmail.com [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
2015-02-10
We present an update to seven stars with long-period planets or planetary candidates using new and archival radial velocities from Keck-HIRES and literature velocities from other telescopes. Our updated analysis better constrains orbital parameters for these planets, four of which are known multi-planet systems. HD 24040 b and HD 183263 c are super-Jupiters with circular orbits and periods longer than 8 yr. We present a previously unseen linear trend in the residuals of HD 66428 indicative of an additional planetary companion. We confirm that GJ 849 is a multi-planet system and find a good orbital solution for the c component: it is a 1 M {sub Jup} planet in a 15 yr orbit (the longest known for a planet orbiting an M dwarf). We update the HD 74156 double-planet system. We also announce the detection of HD 145934 b, a 2 M {sub Jup} planet in a 7.5 yr orbit around a giant star. Two of our stars, HD 187123 and HD 217107, at present host the only known examples of systems comprising a hot Jupiter and a planet with a well constrained period greater than 5 yr, and with no evidence of giant planets in between. Our enlargement and improvement of long-period planet parameters will aid future analysis of origins, diversity, and evolution of planetary systems.
Energy Technology Data Exchange (ETDEWEB)
Mrochek, J.E.; Burtis, C.A.; Scott, C.D. (comps.)
1976-09-01
This document, which covers the period January 1-June 30, 1976, describes progress in the following areas: (1) advanced analytical techniques for the clinical laboratory, (2) fast clinical analyzers, (3) development of a miniaturized analytical clinical laboratory system, (4) centrifugal fast analyzers for animal toxicological studies, and (5) chemical profile of body fluids.
International Nuclear Information System (INIS)
The article considers the problems of necessity of revision of regulations and normative requirements to periodicity of complex impermeability tests for the VVER containment. On the basis of probabilistic approaches the method of conservative prognoses estimations of possibility of reduction of impermeability test time for the containment system is developed taking into account operating data on results the complex tests
Energy Technology Data Exchange (ETDEWEB)
Witzel, Andre [Gepla mbH and Co.KG, Edewecht (Germany); Schulz, Olav [GNS Gesellschaft fuer Nuklear-Service mbH, Gorleben (Germany)
2013-07-01
Especially for nuclear technological plants, periodic inspections of lightning protection systems are of great importance. This article shows the sequence of maintenance programs using the examples of the intermediate storage facilities of the nuclear technological plants Grohnde and Unterweser as well as the central intermediate storage facility in Gorleben and gives a description of the extensive measures of inspecting the external and internal lightning protection and the global earth termination system.
International Nuclear Information System (INIS)
Using a stationary phase approximation to calculate a functional integral defined on continuous overcomplete sets of vectors of the Hilbert space, one derives a generalized semi-classical quantization condition for periodic trajectories in the Hilbert space. This quantization condition is interpreted in terms of a variational principle. Application to the time dependent Hartree-Fock approximation is presented. (orig.)
Xu, Ming; Jiao, Yan; Li, Xiaoming; Cao, Qingfeng; Wang, Xiaoyang
2015-01-01
This paper presents a multi-period optimization model for high margin and zero salvage products in online distribution channels with classifying customers based on number of products required. Taking hotel customers as an example, one is regular customers who reserve rooms for one day, and the other is long term stay (LTS) customers who reserve rooms for a number of days. LTS may guarantee a specific amount of demand and generate opportunity income for a certain number of periods, meanwhile with risk of punishment incurred by overselling. By developing an operational optimization model and exploring the effects of parameters on optimal decisions, we suggest that service providers should make decisions based on the types of customers, number of products required, and duration of multi-period to reduce the loss of reputation and obtain more profit; at the same time, multi-period buying customers should buy products early. Finally, the paper conducts a numerical experiment, and the results are consistent with prevailing situations. PMID:26147663
Czech Academy of Sciences Publication Activity Database
Sehadová, Hana; Doležel, David; Šiffelová, Gulmíra; Šauman, Ivo
?eské Bud?jovice : Entomologický ústav AV ?R, 2002. s. 16. [Czech-Japanese Seminar on Entomology /2./. 05.08.2002-08.08.2002, ?eské Bud?jovice] Institutional research plan: CEZ:AV0Z5007907 Keywords : Periplaneta americana * period Subject RIV: EB - Genetics ; Molecular Biology
Scientific Electronic Library Online (English)
Wanderley Guilherme dos, Santos.
2013-03-01
Full Text Available [...] Abstract in english Between the absolutisms of the 17th and 18th centuries and the democratic variants identified after World War II, there remains a conceptual haze that hinders an understanding of the period's political and institutional history. With the oligarchy viewed sometimes as the seed of democracy and other [...] times as a vestige of autocracy, the period remains vulnerable to subjectivisms. The current article presents a different, trans-locally valid analytical model for the oligarchic system and attempts to demonstrate how the history of the Second Empire and First Republic of Brazil would appear in a preliminary approach using the general model.
Energy Technology Data Exchange (ETDEWEB)
Williams, Dean N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Foster, I. T. [Argonne National Lab. (ANL), Argonne, IL (United States); Middleton, D. E. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Ananthakrishnan, R. [Argonne National Lab. (ANL), Argonne, IL (United States); Siebenlist, F. [Argonne National Lab. (ANL), Argonne, IL (United States); Shoshani, A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sim, A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bell, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Drach, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ahrens, J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jones, P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Brown, D. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Chastang, J. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Cinquini, L. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Fox, P. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Harper, D. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Hook, N. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Nienhouse, E. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Strand, G. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); West, P. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Wilcox, H. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Wilhelmi, N. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Zednik, S. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Hankin, S. [National Oceanic and Atmospheric Administration (NOAA), Washington, DC (United States); Schweitzer, R. [National Oceanic and Atmospheric Administration (NOAA), Washington, DC (United States); Bernholdt, D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chen, M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Miller, R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shipman, G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bharathi, S. [Univ. of Southern California, Marina Del Rey, CA (United States). Information Sciences Institute; Chervenak, A. [Univ. of Southern California, Marina Del Rey, CA (United States). Information Sciences Institute; Schuler, R. [Univ. of Southern California, Marina Del Rey, CA (United States). Information Sciences Institute; Su, M. [Univ. of Southern California, Marina Del Rey, CA (United States). Information Sciences Institute
2010-04-21
This report summarizes work carried out by the ESG-CET during the period October 1, 2009 through March 31, 2009. It includes discussion of highlights, overall progress, period goals, collaborations, papers, and presentations. To learn more about our project, and to find previous reports, please visit the Earth System Grid Center for Enabling Technologies (ESG-CET) website. This report will be forwarded to the DOE SciDAC program management, the Office of Biological and Environmental Research (OBER) program management, national and international collaborators and stakeholders (e.g., the Community Climate System Model (CCSM), the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5), the Climate Science Computational End Station (CCES), the SciDAC II: A Scalable and Extensible Earth System Model for Climate Change Science, the North American Regional Climate Change Assessment Program (NARCCAP), and other wide-ranging climate model evaluation activities).
Directory of Open Access Journals (Sweden)
Eleftherios Giovanis
2012-03-01
Full Text Available In this study two approaches are applied for the prediction of the economic recession or expansion periods in USA. The first approach includes Logit and Probit models and the second is an Adaptive Neuro-Fuzzy Inference System (ANFIS with Gaussian and Generalized Bell membership functions. The in-sample period 1950-2006 is examined and the forecasting performance of the two approaches is evaluated during the out-of sample period 2007-2010. The estimation results show that the ANFIS model outperforms the Logit and Probit model. This indicates that neuro-fuzzy model provides a better and more reliable signal on whether or not a financial crisis will take place.
Directory of Open Access Journals (Sweden)
Derkach V.N.
2014-03-01
Full Text Available Purpose : To determine theoretically similar trends and differences in the periods of sports training athletes and Paralympic athletes with similar qualifications, without disabilities. Material : analyzed more than 80 references. Results : at present insufficiently developed periodization sports training many years to prepare athletes with disorders of the musculoskeletal system. Also - at the stage of maximum realization of individual empowerment athletes. This applies to the immediate preparation for the main competition. In the first case, periodization can be carried out on the basis of the classical theory. Also on stage, maximizing the individual capabilities. Need to adapt this theory to career achievements of athletes. Also, you must consider the disease. Conclusions : The main factors set differences training tools Paralympic athletes and physically healthy: increased attention to the psychological preparation for the Paralympics, inclusive education and sports training individualization programs already in the first stage of their training.
International Nuclear Information System (INIS)
Stem–leader transition and front-streamer inception are two essential conditions for the inception of positive upward leader–streamer system (LSS). Previous models have not considered the initial-leader propagation during dark period and have not been verified systematically. In this paper, a series of positive upward discharge simulation experiments was designed and carried out. Characteristic parameters of the discharge process related to the inception of positive upward LSS, namely, the first-corona inception voltage, the first-corona charge, the dark period, and the LSS inception voltage, were obtained. By comparing these experiment results with simulation results calculated using previous models, it was found that it is improper to assume that the length of the initial leader is a fixed value. Finally, an improved inception model of positive upward LSS considering the leader propagation during dark period was developed and verified with experiment results.
Florek, Wojciech
1999-01-01
Properties of the magnetic translation operators for a charged particle moving in a crystalline potential and a uniform magnetic field show that it is necessary to consider all inequivalent irreducible projective representations of the the crystal lattice translation group. These considerations lead to the concept of magnetic cells and indicate the periodicity of physical properties with respect to the charge. It is also proven that a direct product of such representations d...
Energy Technology Data Exchange (ETDEWEB)
Zee, R.H.; Rose, M.F.
1993-12-31
Objective was to understand the strengthening mechanisms in advanced refractory alloys for high-temperature thermionic applications. During the first 6 months, the role of substitutional solutes in refractory alloy single crystals was identified and modeled using a simple size misfit factor as the governing parameter. During the past period, effort was concentrated on the strengthening effects in various refractory structures and the growth of refractory alloy single crystals. 11 figs, 4 tabs.
Czech Academy of Sciences Publication Activity Database
Náprstek, Ji?í; Fischer, Cyril
Ljubljana : CTP National and University Library of Slovenia, 2015 - (Boltežar, M.), s. 662-671 ISBN 978-961-6536-97-4. [International conference on engineering vibration. Lubla? (SI), 07.09.2015-10.09.2015] R&D Projects: GA ?R(CZ) GA15-01035S Institutional support: RVO:68378297 Keywords : non-linear dynamics * quasi-periodic response * post-critical processes * dynamic stability Subject RIV: JM - Building Engineering
Energy Technology Data Exchange (ETDEWEB)
Williams, Dean N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Foster, I. T. [Argonne National Lab. (ANL), Argonne, IL (United States); Middleton, D. E. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States)
2009-10-15
This report summarizes work carried out by the ESG-CET during the period April 1, 2009 through September 30, 2009. It includes discussion of highlights, overall progress, period goals, collaborations, papers, and presentations. To learn more about our project, and to find previous reports, please visit the Earth System Grid Center for Enabling Technologies (ESG-CET) website. This report will be forwarded to the DOE SciDAC program management, the Office of Biological and Environmental Research (OBER) program management, national and international collaborators and stakeholders (e.g., the Community Climate System Model (CCSM), the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5), the Climate Science Computational End Station (CCES), the SciDAC II: A Scalable and Extensible Earth System Model for Climate Change Science, the North American Regional Climate Change Assessment Program (NARCCAP), and other wide-ranging climate model evaluation activities). During this semi-annual reporting period, the ESG-CET team continued its efforts to complete software components needed for the ESG Gateway and Data Node. These components include: Data Versioning, Data Replication, DataMover-Lite (DML) and Bulk Data Mover (BDM), Metrics, Product Services, and Security, all joining together to form ESG-CET's first beta release. The launch of the beta release is scheduled for late October with the installation of ESG Gateways at NCAR and LLNL/PCMDI. Using the developed ESG Data Publisher, the ESG II CMIP3 (IPCC AR4) data holdings - approximately 35 TB - will be among the first datasets to be published into the new ESG enterprise system. In addition, the NCAR's ESG II data holdings will also be published into the new system - approximately 200 TB. This period also saw the testing of the ESG Data Node at various collaboration sites, including: the British Atmospheric Data Center (BADC), the Max-Planck-Institute for Meteorology, the University of Tokyo Center for Climate System Research, and the Australian National University. This period, a total of 14 national and international sites installed an ESG Data Node for testing. During this period, we also continued to provide production-level services to the community, providing researchers worldwide with access to CMIP3 (IPCC AR4), CCES, and CCSM, Parallel Climate Model (PCM), Parallel Ocean Program (POP), and Cloud Feedback Model Intercomparison Project (CFMIP), and NARCCAP data.
Feng, Y. Katherina; Wright, Jason T.; Nelson, Benjamin; Wang, Sharon X.; Ford, Eric B.; Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.
2015-02-01
We present an update to seven stars with long-period planets or planetary candidates using new and archival radial velocities from Keck-HIRES and literature velocities from other telescopes. Our updated analysis better constrains orbital parameters for these planets, four of which are known multi-planet systems. HD 24040 b and HD 183263 c are super-Jupiters with circular orbits and periods longer than 8 yr. We present a previously unseen linear trend in the residuals of HD 66428 indicative of an additional planetary companion. We confirm that GJ 849 is a multi-planet system and find a good orbital solution for the c component: it is a 1 M Jup planet in a 15 yr orbit (the longest known for a planet orbiting an M dwarf). We update the HD 74156 double-planet system. We also announce the detection of HD 145934 b, a 2 M Jup planet in a 7.5 yr orbit around a giant star. Two of our stars, HD 187123 and HD 217107, at present host the only known examples of systems comprising a hot Jupiter and a planet with a well constrained period greater than 5 yr, and with no evidence of giant planets in between. Our enlargement and improvement of long-period planet parameters will aid future analysis of origins, diversity, and evolution of planetary systems. Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology.
Energy Technology Data Exchange (ETDEWEB)
Kinney, Troy; Reppen, Dag; Yee, David; Schlatter, Jim
2002-03-01
Catalytica Energy Systems Inc. (CESI) is developing a novel catalytic combustion system (called Xonon{reg_sign}) that produces ultra-low emissions for natural gas fired turbine engines. In this project, the Xonon{reg_sign} system was installed on a Kawasaki M1A-13A 1.4 kW engine connected to the Silicon Valley Power electrical grid. The purpose of the project was to demonstrate the ultra-low emission levels of the Xonon{reg_sign} system and to determine the system Reliability, Availability, Maintainability and Durability (RAMD). The engine accumulated 8,128 hours of on-grid operation while exhibiting average NOx levels of 1.3 ppm, CO of 0.9 ppm and unburned hydrocarbons of 1.3 ppm (all values corrected to 15% O{sub 2}). The Xonon{reg_sign} system reliability and availability were 99.2% and 91.2% respectively. Maintainability and durability values were not quantified due to the redesign of some key system components over the course of the program. The RAMD program also included control system development activities to improve the stability of the fuel control system to various levels of load application and shedding. Other control system modifications improved the ability of the system to re-synchronize with the grid after full load rejection.
DEFF Research Database (Denmark)
Johansen, Soren Glud; Thorstenson, Anders
2014-01-01
Emergency orders have shorter lead times but incur extra costs compared to normal orders. We present a discrete-time Markov decision model where normal orders are issued according to a reorder point policy with a fixed order quantity, whereas emergency orders are controlled by a state-dependent reorder point policy with a target stock level. A rapid policy iteration algorithm is used to find and evaluate the policy that minimizes the long-run average cost per review period. In addition to fixed and variable costs for normal and emergency orders our model includes linear holding and backorder costs. The review period is of any given length. Neither the normal order nor the emergency order lead time are required to be integer multiples of the review period. The numerical study shows that the mixed policy found from our Markov decision model generally outperforms the best pure replenishment policy using either only normal or only emergency orders. Our model provides results that are similar to or slightly better than the results obtained with earlier models in the literature. Moreover, because our model accommodates compound Poisson demand, we are able to demonstrate that considerable cost reductions can then be obtained with the mixed policy when compared to the best pure replenishment policy. Finally, using sensitivity analysis we observe that a result on when a mixed policy is most beneficial, which has been found to hold for the simpler model without fixed ordering costs, seems to hold also for the more complex model that we investigate. (C) 2014 Elsevier B.V. All rights reserved.
Internal character of the quasi-periodic response near the resonance of a single non-linear system.
Czech Academy of Sciences Publication Activity Database
Náprstek, Ji?í; Fischer, Cyril
Vol. 108. Kippen : Civil-Comp Press, 2015 - (Kruis, J.; Tsompanakis, Y.; Topping, B.), s. 101 ISBN 978-1-905088-63-8. ISSN 1759-3433. - (Civil-Comp Proceedings. 108). [Civil-Comp 2015. International Conference on Civil, Structural and Environmental Engineering Computing /15./. Praha (CZ), 01.09.2015-04.09.2015] R&D Projects: GA ?R(CZ) GA15-01035S Institutional support: RVO:68378297 Keywords : non-linear dynamics * quasi-periodic response * beating effect * stability of post-critical processes Subject RIV: JM - Building Engineering http://www.ctresources.info/ccp/paper.html?id=8659
Alvi, Ayesha; Devi, S Manjulata; Ahmed, Irshad; Hussain, M Abid; Rizwan, Mohammed; Lamouliatte, Hérve; Mégraud, Francis; Ahmed, Niyaz
2007-01-01
Helicobacter pylori cagA and vacA genotypes have been used for almost a decade as stable entities to link the severity of gastritis and ulcer disease. We describe here microevolution of the two genomic islands, cag pathogenicity island (cagPAI; 40 kb) and tfs3 (16 kb) from isolates obtained at inclusion (one subclone) and after a 10-year period (two subclones) from a duodenal ulcer patient. Our results indicate microevolution in cagA, cagE, and cag7 genes of the cagPAI and open reading frames...
International Nuclear Information System (INIS)
This paper focuses on the Noether symmetries and the conserved quantities for both holonomic and nonholonomic systems based on a new non-conservative dynamical model introduced by El-Nabulsi. First, the El-Nabulsi dynamical model which is based on a fractional integral extended by periodic laws is introduced, and El-Nabulsi—Hamilton's canonical equations for non-conservative Hamilton system with holonomic or nonholonomic constraints are established. Second, the definitions and criteria of El-Nabulsi—Noether symmetrical transformations and quasi-symmetrical transformations are presented in terms of the invariance of El-Nabulsi—Hamilton action under the infinitesimal transformations of the group. Finally, Noether's theorems for the non-conservative Hamilton system under the El-Nabulsi dynamical system are established, which reveal the relationship between the Noether symmetry and the conserved quantity of the system. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Directory of Open Access Journals (Sweden)
El Aroudi A.
2014-01-01
Full Text Available In this paper closed-form conditions for predicting the boundary of period-doubling (PD bifurcation or saddle-node (SN bifurcation in a class of PWM piecewise linear systems are obtained from a time-domain asymptotic approach. Examples of switched system considered in this study are switching dc-dc power electronics converters, temperature control systems and hydraulic valve control systems among others. These conditions are obtained from the steady-state discrete-time model using an asymptotic approach without resorting to frequency-domain Fourier analysis and without using the monodromy or the Jacobian matrix of the discrete-time model as it was recently reported in the existing literature on this topic. The availability of such design-oriented boundary expressions allows to understand the effect of the different parameters of the system upon its stability and its dynamical behavior.
Hai, G. -Q.; Peeters, F.M.
2015-01-01
Based on the metastable electron-pair energy band in a two-dimensional (2D) periodic potential obtained previously by Hai and Castelano [J. Phys.: Condens. Matter 26, 115502 (2014)], we present in this work a Hamiltonian of many electrons consisting of single electrons and electron pairs in the 2D system. The electron-pair states are metastable of energies higher than those of the single-electron states at low electron density. We assume two different scenarios for the singl...
A. F. Bouwman; Drecht, G van; Hoek, K W van der
2007-01-01
Data for the historical years 1970 and 1995 and the FAO-Agriculture Towards 2030 projection are used to calculate N inputs (N fertilizer, animal manure, biological N fixation and atmospheric deposition) and the N export from the field in harvested crops and grass and grass consumption by grazing animals. In most industrialized countries we see a gradual increase of the overall N recovery of the intensive agricultural production systems over the whole 1970-2030 period. In contrast, low N input...
Directory of Open Access Journals (Sweden)
G.S. Vorobjov
2010-01-01
Full Text Available The experimental plant and the general method of modeling of electromagnetic wave processes in multicoupled quasi-optical systems are described. Examples of choosing the optimum regimes of modeling and basic parameters of the investigated electrodynamic systems are shown. The functional scheme of the experimental plant is also described. The general method of modeling of electromagnetic phenomena in resonant and waveguide multicoupled quasi-optical systems is presented for the first time.
International Nuclear Information System (INIS)
The object of this communication is to describe methods used to assess the safety of the Integrated Protection System (SPIN) of the new Nuclear Power Plant. This very complex system is designed to be fault tolerant. The ESCAF simulator was considered to be best suited to the task of dealing with the large number of system components and dependances in the fault trees and providing dominant cut-sets. 3 refs
Xiang-Gruess, M.; Papaloizou, J. C. B.
2015-05-01
In order to study the origin of the architectures of low-mass planetary systems, we perform numerical surveys of the evolution of pairs of coplanar planets in the mass range (1-4) M?. These evolve for up to 2 × 107 yr under a range of orbital migration torques and circularization rates assumed to arise through interaction with a protoplanetary disc. Near the inner disc boundary, significant variations of viscosity, interaction with density waves or with the stellar magnetic field could occur and halt migration, but allow circularization to continue. This was modelled by modifying the migration and circularization rates. Runs terminated without an extended period of circularization in the absence of migration torques gave rise to either a collision, or a system close to a resonance. These were mostly first order with a few per cent terminating in second-order resonances. Both planetary eccentricities were small divergent migration occurs causing period ratios to increase. Depending on its strength the whole period ratio range between 1 and 2 can be obtained. A few systems close to second-order commensurabilities also occur. In contrast to when arising through convergent migration, resonant trapping does not occur and resonant angles circulate. Thus, the behaviour of the resonant angles may indicate the form of migration that led to near resonance.
DEFF Research Database (Denmark)
Dicke, Ulrike; Ewert, Stephan D.
2007-01-01
Periodic amplitude modulations AMs of an acoustic stimulus are presumed to be encoded in temporal activity patterns of neurons in the cochlear nucleus. Physiological recordings indicate that this temporal AM code is transformed into a rate-based periodicity code along the ascending auditory pathway. The present study suggests a neural circuit for the transformation from the temporal to the rate-based code. Due to the neural connectivity of the circuit, bandpass shaped rate modulation transfer functions are obtained that correspond to recorded functions of inferior colliculus IC neurons. In contrast to previous modeling studies, the present circuit does not employ a continuously changing temporal parameter to obtain different best modulation frequencies BMFs of the IC bandpass units. Instead, different BMFs are yielded from varying the number of input units projecting onto different bandpass units. In order to investigate the compatibility of the neural circuit with a linear modulation filterbank analysis asproposed in psychophysical studies, complex stimuli such as tones modulated by the sum of two sinusoids, narrowband noise, and iterated rippled noise were processed by the model. The model accounts for the encoding of AM depth over a large dynamic range and for modulation frequency selective processing of complex sounds.
International Nuclear Information System (INIS)
Appendix A covers major activities of the Artificial Heart Development program that supported the design, fabrication, and test of the system demonstration units. Section A.1.0 provides a listing beyond that of the body of the report on the components needed for an implantation. It also presents glove box sterilization calibration results and results of an extensive mock circulation calibration. Section A.2.0 provides detail procedures for assembly, preparing for use, and the use of the system and major components. Section A.3.0 covers the component research and development activities undertaken to improve components of the existing system units and to prepare for a future prototype system. Section A.4.0 provides a listing of the top assembly drawings of the major systems variations fabricated and tested
Alvi, Ayesha; Devi, S. Manjulata; Ahmed, Irshad; Hussain, M. Abid; Rizwan, Mohammed; Lamouliatte, Hérve; Mégraud, Francis; Ahmed, Niyaz
2007-01-01
Helicobacter pylori cagA and vacA genotypes have been used for almost a decade as stable entities to link the severity of gastritis and ulcer disease. We describe here microevolution of the two genomic islands, cag pathogenicity island (cagPAI; 40 kb) and tfs3 (16 kb) from isolates obtained at inclusion (one subclone) and after a 10-year period (two subclones) from a duodenal ulcer patient. Our results indicate microevolution in cagA, cagE, and cag7 genes of the cagPAI and open reading frames G, P, and L in tfs3, which possibly leads to inactivation or pseudogenization of these genes. Interestingly, no significant reduction in the severity of gastroduodenal pathology was found. These results point to an obvious difficulty in correlating the continuously evolving virulence factors such as the cagPAI genes with disease characteristics that appear to remain stable. PMID:17942650
Directory of Open Access Journals (Sweden)
Ngampongsai, W.
2007-05-01
Full Text Available The objective of this research was to study the effects of feeding systems on feed intake and milk yield of 50 % Thai Native-Anglo Nubian crossbred does. Twenty four does at 90 days of pregnancy werekept in individual pens and fed Napier grass (Pennisetum purpureum ad libitum. They were alloted to 3 groups of different feeding systems according to a completely randomized design: 1 no supplementedconcentrate during late pregnancy period but supplemented with 14 % crude protein (CP concentrate ad libitum during post-partum period; 2 supplemented with 14% CP concentrate ad libitum both during latepregnancy and post-partum periods; and 3 as group 2 but the concentrate contained 18% CP. Feeding systems significantly (P0.05. They were 865.32; 982.98 and 1,026.60 g/d or 62.27; 66.71 and 68.51 g/BW0.75/d or 1.73; 1.89 and 1.93 %BW, respectively. Similarly, feeding systems were significantly(P0.05. They were 1,599.19; 1,557.44 and 1,682.23g/d or 123.41; 109.22 and 117.17 g/BW0.75/d or 3.57; 3.04 and 3.25 %BW in group 1, 2 and 3 respectively. Feeding systems significantly (P<0.05 affected milk yield of does. Milk yield in weeks 1, 2 and 3 ofgroup 1 (1,043; 1,220 and 1,291 ml/d, respectively was significantly (P<0.05 lower than those of groups 2 and 3 (1,793; 1,964; 1,992 and 1,695; 1,901; 1,729 ml/d, respectively. Does giving twin kids produced significantlyhigher milk yield than single kid does.
AltiKa: a Ka-band Altimetry Payload and System for Operational Altimetry during the GMES Period
Directory of Open Access Journals (Sweden)
Jacques Verron
2006-03-01
Full Text Available This paper describes the Ka-band altimetry payload and system that has beenstudied for several years by CNES, ALCATEL SPACE and some science laboratories.Altimetry is one of the major elements of the ocean observing system to be madesustainable through the GEOSS (Global Earth Observation System of Systems and GMES(Global Monitoring of the Environment and Security programs. A short review of somemission objectives to be fulfilled in terms of mesoscale oceanography in the frame of theGEOSS and GMES programs is performed. To answer the corresponding requirements, theapproach consisting in a constellation of nadir altimeter is discussed. A coupled Ka-bandaltimeter-radiometer payload is then described; technical items are detailed to explain howthis payload shall meet the science and operational requirements, and expectedperformances are displayed. The current status of the payload development and flightperspectives are given.
Li, Yongkun; Wang, Pan; LI Bing
2015-01-01
In this paper, we first propose a single-species system with impulsive effects on time scales and by establishing some new comparison theorems of impulsive dynamic equations on time scales, we obtain sufficient conditions to guarantee the permanence of the system. Then we prove a Massera type theorem for impulsive dynamic equations on time scales and based on this theorem, we establish a criterion for the existence and uniformly asymptotic stability of unique positive almost...
International Nuclear Information System (INIS)
We present high-precision radial velocity (RV) observations of four solar-type (F7-G5) stars—HD 79498, HD 155358, HD 197037, and HD 220773—taken as part of the McDonald Observatory Planet Search Program. For each of these stars, we see evidence of Keplerian motion caused by the presence of one or more gas giant planets in long-period orbits. We derive orbital parameters for each system and note the properties (composition, activity, etc.) of the host stars. While we have previously announced the two-gas-giant HD 155358 system, we now report a shorter period for planet c. This new period is consistent with the planets being trapped in mutual 2:1 mean-motion resonance. We therefore perform an in-depth stability analysis, placing additional constraints on the orbital parameters of the planets. These results demonstrate the excellent long-term RV stability of the spectrometers on both the Harlan J. Smith 2.7 m telescope and the Hobby-Eberly telescope.
Ding, Yingchun; Zhang, Fengli; Chen, Zhaoyang; Lin, Chengyou; Yu, M Y
2013-01-01
Random excitation of intense periodic highly-localized single-cycle light pulses in a stochastic background by continuous-wave stimulated Brillouin scattering in long optical fibers with weak feedback is found experimentally. Events with low period numbers are dominant and the optical feedback is crucial for the phenomenon. A three-wave coupling model for the phenomenon is proposed. The results are in good qualitative agreement with the observed phenomenon. The latter should be relevant to the understanding of similar rogue wave events in other nonlinear dissipative systems.
Feng, Y Katherina; Nelson, Benjamin; Wang, Sharon X; Ford, Eric B; Marcy, Geoffrey W; Isaacson, Howard; Howard, Andrew W
2015-01-01
We present an update to seven stars with long-period planets or planetary candidates using new and archival radial velocities from Keck-HIRES and literature velocities from other telescopes. Our updated analysis better constrains orbital parameters for these planets, four of which are known multi-planet systems. HD 24040 b and HD 183263 c are super-Jupiters with circular orbits and periods longer than 8 yr. We present a previously unseen linear trend in the residuals of HD 66428 indicative on an additional planetary companion. We confirm that GJ 849 is a multi-planet system and find a good orbital solution for the c component: it is a $1 M_{\\rm Jup}$ planet in a 15 yr orbit (the longest known for a planet orbiting an M dwarf). We update the HD 74156 double-planet system. We also announce the detection of HD 145934 b, a $2 M_{\\rm Jup}$ planet in a 7.5 yr orbit around a giant star. Two of our stars, HD 187123 and HD 217107, at present host the only known examples of systems comprising a hot Jupiter and a planet...
Directory of Open Access Journals (Sweden)
Romanchuk ?.P.
2010-03-01
Full Text Available The vegetative adjusting of activity of the cardio-vessel system of girls is investigational. In an experiment took part girls of 9-12 years old. A type of sport is a dancing aerobics. The indexes of general power of spectrum of variability of cardiac rhythm are presented, systole and diastole arteriotony. Motion of the adaptation re-erecting is appraised under influence of the physical loadings in the conditions of current and operative control. Certain change activity and tone of vegetative influences on the cardio-vessel system. They determine the features of the further adaptation re-erecting in an organism.
International Nuclear Information System (INIS)
The main research activity on our project continues to be the very active field of proton-transfer spectroscopy. Categories of research are: (1) Systematics of Proton-Transfer classes; (2) Picosecond Spectroscopy of Proton-Transfer in Lumichrome (a photolysis product of riboflavin); (3) Proton-Transfer Laser Research; (4) Computer Calculations on Proton-Transfer Systems; and (5) Unscheduled Research. New facets of the research program are: (1) Charge-Transfer (CT) Perturbation of Proton-Transfer Spectroscopy; (2) Super Computer Calculations on Proton-Transfer; (3) Dielectric Effects on Extended Dipoles in Proton-Transfer Spectroscopy; and (4) Proton-Transfer in Biological Systems
Energy Technology Data Exchange (ETDEWEB)
Dutta, Saikat; Wu, Kevin C.-W., E-mail: hmkao@cc.ncu.edu.tw, E-mail: kevinwu@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Kao, Hsien-Ming, E-mail: hmkao@cc.ncu.edu.tw, E-mail: kevinwu@ntu.edu.tw [Department of Chemistry, National Central University, Chung-Li 32054, Taiwan (China)
2014-11-01
This manuscript presents the preparation and catalytic application of highly ordered benzene bridged periodic mesoporous organosilicas (PMOs) functionalized with carboxylic acid (–COOH) group at varied density. The COOH-functionalized PMOs were synthesized by one-step condensation of 1,4-bis (triethoxysilyl) benzene and carboxylic group containing organosilane carboxyethylsilanetriol sodium salt using Brij-76 as the template. The obtained materials were characterized by a mean of methods including powder X-ray diffraction, nitrogen adsorption-desorption, scanning- and transmission electron microscopy, and {sup 13}C solid-state nuclear magnetic resonance measurements. The potentials of the obtained PMO materials with ordered mesopores were examined as solid catalysts for the chemical conversion of fructose to 5-hydroxymethylfurfural (HMF) in an organic solvent. The results showed that COOH-functionalized PMO with 10% COOH loading exhibited best results for the fructose to HMF conversion and selectivity. The high surface area, the adequate density acid functional group, and the strength of the PMO materials contributing to a promising catalytic ability were observed.
International Nuclear Information System (INIS)
The first part of the parer considers the general problem of optimal yearly unit commitment in the new economical conditions in Bulgaria. The second part deals with non-convex problem , taking into account some costs for starting and stopping of power systems. The transition from yearly commitment to weekly or daily dispatching is commented
Gundra, Kondayya
2011-01-01
Pariser-Parr-Pople (P-P-P) model Hamiltonian is employed frequently to study the electronic structure and optical properties of $\\pi$-conjugated systems. In this paper we describe a Fortran 90 computer program which uses the P-P-P model Hamiltonian to solve the Hartree-Fock (HF) equation for infinitely long, one-dimensional, periodic, $\\pi$-electron systems. The code is capable of computing the band structure, as also the linear optical absorption spectrum, by using the tight-binding (TB) and the HF methods. Furthermore, using our program the user can solve the HF equation in the presence of a finite external electric field, thereby, allowing the simulation of gated systems. We apply our code to compute various properties of polymers such as $trans$-polyacetylene ($t$-PA), poly-\\emph{para}-phenylene (PPP), and armchair and zigzag graphene nanoribbons, in the infinite length limit.
Siwak, Michal; Szymanski, Tomasz; Kurpinska-Winiarska, Maria; Winiarski, Maciej; Koziel-Wierzbowska, Dorota; Waniak, Waclaw; Drahus, Michal
2012-01-01
We have analyzed the available spectra of WW And and for the first time obtained a reasonably well defined radial velocity curve of the primary star. Combined with the available radial velocity curve of the secondary component, these data led to the first determination of the spectroscopic mass ratio of the system at q-spec = 0.16 +/- 0.03. We also determined the radius of the accretion disc from analysis of the double-peaked H-alpha emission lines. Our new, high-precision, Johnson VRI and the previously available Stromgren vby light curves were modelled with stellar and accretion disc models. A consistent model for WW And - a semidetached system harbouring an accretion disc which is optically thick in its inner region, but optically thin in the outer parts - agrees well with both spectroscopic and photometric data.
Ravet, Stéphanie; Labied, Soraya; Blacher, Silvia; Frankenne, Francis; Munaut, Carine; Fridman, Viviana; Beliard, Aude; Foidart, Jean-Michel; Nisolle, Michelle
2007-01-01
BACKGROUND: Levonorgestrel-releasing intrauterine system (LNG-IUS), although inserted to reduce heavy menstruation, causes irregular early transient bleeding. The objective of the study was to document quantitative changes in endometrial vessels of short- ( or =12 months) LNG users. The area, density and maturation of endometrial vessels were quantified in 19 endometrial biopsies of women with LNG-IUS and in 10 normally ovulating patients during mid-luteal phas...
International Nuclear Information System (INIS)
On the basis of ERBR (existing residential building retrofit) work in the 11th five-year period, energy efficiency retrofits for old residential buildings have been further promoted in northern regions of China during the 12th five-year period. ERBR projects are capable of not only achieving energy conservation and emissions reductions but also providing warmer rooms for residents during cold winters. Therefore, this project should be continued in northern regions of China following a long-term management mode. With the aim of exploring methods and mechanisms for the evaluation of the retrofit effect, an evaluation method was established with the application of the multi-level expert evaluation method. The evaluation indexes cover the aspects of policy mechanisms, financing modes and technical measures. A rewards and punishment mechanism according to the evaluation system was also suggested. Such an evaluation system can be used as a valuable reference for future implementation of energy efficiency retrofit work. - Highlights: • With the AHPD method, the evaluation system of the ERBR was set up to complete. • There are 29 indicators, including policies, financings and technologies. • Rewards and punishment mechanisms are offered to the ERBR. • For weight value more than 0.06, long-term practice and accumulation are needed
Messina, Sergio; Worters, Hannah L; Bromage, Gordon E; Sanchez, Richardo Zanmar
2015-01-01
Stellar rotation depends on different parameters. The range of values of these parameters causes the dispersion in the rotation period distributions observed in young stellar clusters/associations. We focus our investigation on the effects of different circumstellar environments on stellar rotation. More specifically, we are searching in stellar Associations for visual triple systems where all stellar parameters are similar, with the only exceptions of the unknown initial rotation period, and of the circum-stellar environment, in the sense that one of the two about equal-mass components has a close-by third 'perturber' component. In the present study we analyse the 35-Myr old visual triple system TYC 9300-0891-1AB + TYC 9300-0529-1 in the young Octans stellar association consisting of three equal-mass K0V components. We collected from the literature all information that allowed us to infer that the three components are actually physically bound forming a triple system and are members of the Octans Association...
An EXOSAT observation of 1.5 orbital cycles of the 0.7 day short-period RS CVn system ER Vul
International Nuclear Information System (INIS)
Two EXOSAT observations of the short-period 0.7 day eclipsing RS Cvn binary system ER Vul are reported. The first observation in 1984 October lasted for 3 hr. while the second in 1985 May covered 1.5 orbital cycles. The overall counting rate decreased by a factor of approx. 2 in the 6 months separating the two observations. No strong orbital modulation of the X-ray flux was evident, nor were any deep eclipses seen. The spectrum measured in the 0.05-6 keV band was well fitted by a two-component thermal plasma model with temperatures of 6 and 40 million degrees. (author)
Moutou, C; Mayor, M; Bouchy, F; Benz, W; Lovis, C; Naef, D; Pepe, F; Queloz, D; Santos, N C; Segransan, D; Sousa, S G; Udry, S
2014-01-01
We describe radial-velocity time series obtained by HARPS on the 3.60 m telescope in La Silla (ESO, Chile) over ten years and report the discovery of five new giant exoplanets in distant orbits; these new planets orbit the stars HD 564, HD 30669, HD 108341, and BD-114672. Their periods range from 492 to 1684 days, semi-major axes range from 1.2 to 2.69 AU, and eccentricities range from 0 to 0.85. Their minimum mass ranges from 0.33 to 3.5 Mjup. We also refine the parameters of two planets announced previously around HD 113538, based on a longer series of measurements. The planets have a period of 663+-8 and 1818+-25 days, orbital eccentricities of 0.14+-0.08 and 0.20+-0.04, and minimum masses of 0.36+-0.04 and 0.93+-0.06 Mjup. Finally, we report the discovery of a new hot-Jupiter planet around an active star, HD 103720; the planet has a period of 4.5557+-0.0001 days and a minimum mass of 0.62+-0.025 Mjup. We discuss the fundamental parameters of these systems and limitations due to stellar activity in quiet s...
Scientific Electronic Library Online (English)
S.H., Tang; H., Nouri; O., Motlagh.
Full Text Available The bacteria foraging algorithm (BFA) is a new computation technique inspired by the social foraging behaviour of Escherichia coli (E. coli) bacteria. Since the introduction of the BFA by Kevin M. Passino, there have been many challenges in employing this algorithm to problems other than those for w [...] hich the algorithm was proposed. This research aims to apply this emerging optimisation algorithm to develop a mixed-integer programming model for designing cellular manufacturing systems (CMSs), and production planning in dynamic environments. In dynamic environments, product mix and part demand vary under multi-period planning horizons. Thus the best-designed cells for one period may not be adequate for subsequent periods, requiring their reconstruction. The advantages of the proposed model are as follows: consideration of batch inter-cell and intra-cell material handling by assuming the sequence of operations, allowing for alternative process plans for part types, and consideration of machine copying, with an emphasis on the effect of trade-offs between production and outsourcing costs. The goal is to minimise the sum of the machines' constant and variable costs, inter-cell and intra-cell material handling costs, reconstruction costs, partial subcontracting costs, and inventory carrying costs. In addition, a newly-developed BFA-based optimisation algorithm has been compared with the branch and bound algorithm. The results suggest that the proposed algorithm performs better than related works.
Esposito, P; Dall'Osso, S; Covino, S
2013-01-01
RX J0806.3+1527 (HM Cnc) is a pulsating X-ray source with 100 per cent modulation on a period of 321.5 s (5.4 min). This period reflects the orbital motion of a close binary system consisting of two interacting white dwarfs. Here we present a series of simultaneous X-ray (0.2-10 keV) and near-ultraviolet (2600 angstrom and 1928 angstrom) observations carried out with the Swift satellite. In the near-ultraviolet the counterpart of RX J0806.3+1527 was detected at flux densities consistent with a blackbody with temperature 27E+3 K. We found that the emission at 2600 angstrom is modulated at the 321.5-s period, with the peak ahead of the X-ray one by 0.28 cycles and coincident, within 0.05 cycles, with the optical. This phase-shift measurement confirms that the X-ray hot spot (located on the primary white dwarf) is at about 80-100 degrees from the direction connecting the two white dwarfs. Albeit at lower significance, the 321.5-s signature is present also in the 1928-angstrom data; at this wavelength, however, t...
DEFF Research Database (Denmark)
Jensen, Jens Oluf; Li, Qingfeng
2005-01-01
Polymer electrolyte membrane fuel cell (PEMFC) technology based on Nafion membranes can operate at temperatures around 80°C. The new development in the field is high temperature PEMFC for operation above 100°C, which has been successfully demonstrated through the previous EC Joule III and the 5th framework programme. New challenges are encountered, bottlenecks for the new technology have been identified, and new concepts and solutions have been provisionally identified. FURIM is directed at tackling these key issues by concentrating on the further materials development, compatible technologies, and system integration of the high temperature PEMFC. The strategic developments of the FURIM are in three steps: (1) further improvement of the high temperature polymer membranes and related materials; (2) development of technological units including fuel cell stack, hydrocarbon reformer, afterburner and power management system, that are compatible with the HT-PEMFC; and (3) integration of the HT-PEMFC stack with these compatible subunits. The main goal of the project is a 2kWel HT-PEMFC stack operating in a temperature range of 120-220°C, with a single cell performance target of 0.7 A/cm² at a cell voltage around 0.6 V. The target durability is more than 5,000 hours. A hydrocarbon reformer and a catalytic burner are to be developed and integrated with the stack. The key issue of the project is development and improvement of the temperature-resistant polymer membranes with respect to durability, conductivity, mechanical and other properties. For this purpose, basic polymers will be first synthesized and optimized. Different routes to functionalize the polymers will be explored to increate proton conductivity. By the development of advanced materials, demonstration of the high temperature PEMFC stack and integration of such a system, FURIM is expected to sufficiently promote the commercialisation of the fuel cell technology for both vehicle propulsion and stationary applications.
Siwak, Michal; Zola, Stanislaw; Szymanski, Tomasz; Kurpinska-Winiarska, Maria; Winiarski, Maciej; Koziel-Wierzbowska, Dorota; Waniak, Waclaw; Drahus, Michal
2012-01-01
We have analyzed the available spectra of WW And and for the first time obtained a reasonably well defined radial velocity curve of the primary star. Combined with the available radial velocity curve of the secondary component, these data led to the first determination of the spectroscopic mass ratio of the system at q-spec = 0.16 +/- 0.03. We also determined the radius of the accretion disc from analysis of the double-peaked H-alpha emission lines. Our new, high-precision, ...
Doern, GV; Brueggemann, AB; Dunne, WM; Jenkins, SG; Halstead, DC; McLaughlin, JC
1997-01-01
Blood culture records from 1994 to 1995 from five U.S. medical centers all using the Difco ESP continuous monitoring blood culture system were reviewed retrospectively. Among a total of 7,362 isolates of bacteria and yeasts, only 0.1% of possibly significant isolates would have been missed had blood cultures been routinely incubated for 4 days instead of the 5 days recommended by the manufacturer. Conversely, numerous contaminants, detected only on day 5, would have been eliminated by a 4-day...
International Nuclear Information System (INIS)
During FY97, the University of Wisconsin Fusion Technology Institute personnel have participated in the ARIES-RS and the ARIES-ST projects. The main areas of effort are: (1) neutronics analysis; (2) shielding of components and personnel; (3) neutron wall loading distribution; (4) radiation damage to in-vessel components; (5) components lifetimes; (6) embrittled materials designs issues; (7) stress and structural analysis; (8) activation, LOCA, and safety analysis; (9) support and fabrication of components; (10) vacuum system; and (11) maintenance. Progress made in these areas are summarized
Shafigh, Farhad; Defersha, Fantahun M.; Moussa, Soha Eid
2015-01-01
In this paper, we develop a new mathematical model that integrates layout configuration and production planning in the design of dynamic distributed layouts. The model incorporates a number of important manufacturing attributes such as demand fluctuation, system reconfiguration, lot splitting, work load balancing, alternative routings, machine capability and tooling requirements. In addition, the model allows several cost elements to be optimized in an integrated manner. These costs are associated with material handling, machine relocation, setup, inventory carrying, in-house production and subcontracting needs. Numerical examples of different sizes are presented to illustrate the nature of the developed model and shed light on several managerial insights.
This is a compendium of resources related to the periodic chart. From this site, one can surf a wide variety of presentations of the Periodic Chart of the Chemical Elements. Categories include: Periodic Tables with Basic nformation ; Periodic Table Tests; Periodic Table Link Lists; Periodic Table Games; Periodic Table Projects;Periodic Table News; Periodic Table Books; Software Downloads and much, much more. This site was last updated 11/02/2003.
Energy Technology Data Exchange (ETDEWEB)
Funk, Carolin; Uhlig, Jeanette; Zoch, Immo (eds.)
2011-10-15
In consideration of strategic climate mitigation, energy security and economic competitiveness goals, the EU passed the Directive 2009/28/EC, including a binding target of 20 per cent renewable energy consumption in the EU by 2020. This target is comprehensive and includes energy generation, transport, heating and cooling sectors. In 2008, renewable energy consumption in the EU was about 10 per cent. So meeting the 20 per cent renewable energy objective will require massive changes in energy production, transmission and consumption in the EU. Furthermore, it is obvious that the development of the energy system will not stop in 2020, but that it will continue towards 2050 and beyond. Over the past century, the European electricity system was developed in line with a national utilit y perspective which heavily emphasised large, centralised conventional power production. Investment decisions for new energy infrastructure and technology were typically made at the national level. In the future, much more energy production will be based on local or regional renewable energy sources (RES). Many consumers may also become energy producers feeding into the infrastructures. Transnational energy transfers will gain in importance. These changes will require very different electricity and gas infrastructures and decision-making processes from today. Lack of infrastructure capacity is already a barrier for the further deployment of RES-based energy production in some regions in Europe. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Smyrl, W.H.; Owens, B.B.
2002-09-05
The long-term objective of research has been to perform the enabling materials research necessary for the development of a battery oriented to the consumer market with special requirements in terms of safety, cycling life, and high specific energy and power. We have discovered novel processing of V{sub 2}O{sub 5} gels that leads to aerogel (ARG) and xerogel (XRG) films with specific energy and Li insertion capacity that are much higher than for other amorphous or crystalline forms of V{sub 2}O{sub 5}. We have also found that the new materials will host Mg{sup +2} and other cations which should be the basis for novel high-energy, high-power consumer battery systems. The investigation has examined (1) low-temperature synthesis of V{sub 2}O{sub 5} aerogel host materials, (2) characterization of insertion of Mg{sup 2+}, Zn{sup 2+}, and Al{sup 3+} into the V{sub 2}O{sub 5} hosts, (3) anode materials for the new systems, and alternate anode materials to replace the intrinsically unsafe lithium metal for lithium batteries, and (4) the feasibility of safer, nonaqueous, high-performance battery designs.
International Nuclear Information System (INIS)
In 1988 the Ministry of Social Affairs and Employment commissioned TNO Radiological Service to set up a National Dose REgistration and Information System (NDRIS). The government had three reasons in view to build NDRIS: To improve radiation protection by supervising the occupational doses of radiation workers by using one central database system; To improve the reliability of long term storage of dose data; To improve the possibilities for statistical analysis of occupational doses to guide policy making. Each approved dosimetry service (ADS) in the country sends its dose information to NDRIS on a monthly basis. IN its turn NDRIS sends back for each worker monitored by that ADS, the integrated dose as measured by any ADS. This creates the possibility for each ADS to report to the workers their total annual dose irrespectively whether they work for more than one employer or are monitored by more than one ADS, either simultaneously or successively in the course of the year. European legislation requires that the occupational dose should be controlled in this way. The availability of the centralized database replaces the need of a radiation passbook for national use. The passbook that is needed by radiation workers during interstate travelling can be produced using data from NDRIS
International Nuclear Information System (INIS)
The development of the microstructure of C3S paste and a Portland cement paste was studied between 7 and 24 h by means of backscattered electrons in a field-emission SEM. The course of hydration was measured by isothermal calorimetry. While the abundant occurrence of Hadley grains (hollow-shells) in Portland cement systems is well documented from a number of SEM and other microscopy studies, some earlier reports have noted that Hadley grains do not form in C3S or alite paste alone. This report shows evidence of Hadley grains in C3S paste, and follows their development from middle to late hydration stages. At around 10 h the microstructure with respect to Hadley grains were seen to develop in a very similar manner in C3S and cement. In both systems, a narrow gap often developed between the receding anhydrous cores and layer of reaction product enveloping the cores. By 1 day, Hadley grains had continued to develop only in the cement paste, where they became a prominent feature. Only small 'hollowed-out' hydration shells were observed in the C3S paste by 1 day. These were presumably reminiscences of the small gapped Hadley grains seen at the earlier hydration stages
Directory of Open Access Journals (Sweden)
Koh-ichi Nakamura
2008-02-01
Full Text Available Feeding and the circadian system regulate lipid absorption and metabolism, and the expression of enzymes involved in lipid metabolism is believed to be directly controlled by the clock system. To investigate the interaction between the lipid metabolism system and the circadian system, we analyzed the effect of a CLOCK/BMAL1 heterodimer on the transcriptional regulation of PPAR-controlled genes through PPAR response elements (PPREs. Transcription of acyl-CoA oxidase, cellular retinol binding protein II (CRBPII, and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA synthase was altered by CLOCK/BMAL1, and transcriptional activity via PPRE by PPARs/RXRÃŽÂ± was enhanced by CLOCK/BMAL1 and/or by PPARs ligand/activators. We also found that CLOCK/BMAL1-mediated transcription of period (PER and cryptochrome (CRY was modulated by PPARÃŽÂ±/RXRÃŽÂ±. These results suggest that there may be crosstalk between the PPARs/RXRÃŽÂ±-regulated system and the CLOCK/BMAL1-regulated system.
Periodically Driven Holographic Superconductor
Li, Wei-Jia; Tian, Yu; Zhang, Hongbao(Theoretische Natuurkunde, Vrije Universiteit Brussel and The International Solvay Institutes, Pleinlaan 2, B-1050, Brussels, Belgium)
2013-01-01
As a first step towards our holographic investigation of the far-from-equilibrium physics of periodically driven systems at strong coupling, we explore the real time dynamics of holographic superconductor driven by a monochromatically alternating electric field with various frequencies. As a result, our holographic superconductor is driven to the final oscillating state, where the condensate is suppressed and the oscillation frequency is controlled by twice of the driving fr...
International Nuclear Information System (INIS)
This research focused on the pre-Hispanic ceramic production and distribution systems of the Maipo region in central Chile by means of determining the concentration of the chemical elements in pottery of the Aconcagua culture (900-1450 A.D.) with instrumental neutron activation analysis (INAA). Pottery fragments from eight archaeological sites and natural clays from the study region were included. The differences in chemical composition between subsets of the sample (sites, paste group and ceramic type) were interpreted as indicators of resource and ceramic production locations as well as the imprint of the geological background. These results contributed to the understanding of the Aconcagua ceramic assemblage and helped to test some hypotheses about the Aconcagua social organization. (author)
DEFF Research Database (Denmark)
Li, Qingfeng; Jensen, Jens Oluf
2007-01-01
The new development in the field of polymer electrolyte membrane fuel cell (PEMFC) is high temperature PEMFC for operation above 100°C, which has been successfully demonstrated through the previous EC Joule III and the 5th framework programme. New challenges are encountered, bottlenecks for the new technology have been identified, and new concepts and solutions have been provisionally identified. FURIM is directed at tackling these key issues by concentrating on the further materials development, compatible technologies, and system integration of the high temperature PEMFC. The strategic developments of the FURIM are in three steps: (1) further improvement of the high temperature polymer membranes and related materials; (2) development of technological units including fuel cell stack, hydrocarbon reformer and afterburner, that are compatible with the HT-PEMFC; and (3) integration of the HT-PEMFC stack with these compatible subunits. The main goal of the project is a 2kWel HT-PEMFC stack operating in a temperature range of 150-200°C, with a single cell performance target of 0.7 A/cm² at a cell voltage around 0.6 V. The target durability is more than 5,000 hours. A hydrocarbon reformer and a catalytic burner are to be developed and integrated with the stack. The key issue of the project is development and improvement of the temperature-resistant polymer membranes with respect to durability, conductivity, mechanical and other properties. For this purpose, basic polymers will be first synthesized and optimized. Different routes to functionalize the polymers will be explored to increate proton conductivity. By the development of advanced materials, demonstration of the high temperature PEMFC stack and integration of such a system, FURIM is expected to sufficiently promote the commercialisation of the fuel cell technology for both vehicle propulsion and stationary applications.
UBVR-photometry of the CQ Cep system, the change of the period and mass loss of the Wolf-Rayet star
International Nuclear Information System (INIS)
The new photoelectric UBVR-observations have been obtained for the eclipsing binary system CQ Cep (WN7+O7, p=1sup(d), 641246). These observations, together with all published photographic and photoelectric data from 1899 to 1981, allow to find out change (decreasing) of the period for the system CQ Cep: t=(-0.019+-0.006) s/yr. The rate of the matter outflow from the star WN7 to the companion star 07 is greater than (0.69+-0.22)x10-5 M/yr., where M is the mass of the Sun One may expect the mass loss rate for the separate star WN7 to be close to 10-5 M/yr
Kupfer, T; Heber, U; Østensen, R H; Barlow, B N; Maxted, P F L; Heuser, C; Schaffenroth, V; Gänsicke, B T
2015-01-01
The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding hot subdwarf stars with massive compact companions like massive white dwarfs (M>1.0 M$_\\odot$), neutron stars, or stellar-mass black holes. We present orbital and atmospheric parameters and put constraints on the nature of the companions of 12 close hot subdwarf B star (sdB) binaries found in the course of the MUCHFUSS project. The systems show periods between 0.14 and 7.4 days. Three systems most likely have white dwarf companions. SDSS J083006.17+475150.3 is likely to be a rare example of a low-mass helium-core white dwarf. SDSS J095101.28+034757.0 shows an excess in the infrared that probably originates from a third companion in a wide orbit. SDSS J113241.58-063652.8 is the first helium deficient sdO star with a confirmed close companion. This study brings to 142 the number of sdB binaries with orbital periods of less than 30 days and with measured mass functions. We present an analysis of the minimu...
International Nuclear Information System (INIS)
An implementation of the vector potential approach (VPA) for treating the response of infinite periodic systems to static and dynamic electric fields has been initiated within the CRYSTAL code. The VPA method is based on the solution of a time-dependent Hartree-Fock or Kohn-Sham equation for the crystal orbitals wherein the usual scalar potential, that describes interaction with the field, is replaced by the vector potential. This equation may be solved either by perturbation theory or by finite field methods. With some modification all the computational procedures of molecular ab initio quantum chemistry can be adapted for periodic systems. Accessible properties include the linear and nonlinear responses of both the nuclei and the electrons. The programming of static field pure electronic (hyper)polarizabilities has been successfully tested. Dynamic electronic (hyper)polarizabilities, as well as infrared and Raman intensities, are in progress while the addition of finite fields for calculation of vibrational (hyper)polarizabilities, through nuclear relaxation procedures, will begin shortly
Directory of Open Access Journals (Sweden)
Coskun Erdal
2006-03-01
Full Text Available Abstract Background Ventriculoperitoneal (VP shunts are used for intracranial pressure management and temporary cerebrospinal fluid (CSF drainage. Infection of the central nervous system (CNS is a major cause of morbidity and mortality in patients with CSF shunts. The aim of the present study was to evaluate the clinical features, pathogens, and outcomes of 22 patients with CSF shunt infections collected over 4 years. Methods The patients with shunt insertions were evaluated using; age, sex, etiology of hydrocephalus, shunt infection numbers, biochemical and microbiological parameters, prognosis, clinical infection features and clinical outcome. Results The most common causes of the etiology of hydrocephalus in shunt infected patients were congenital hydrocephalus-myelomeningocele (32% and meningitis (23%. The commonest causative microorganism identified was Staphylococcus (S. aureus, followed by Acinetobacter spp., and S. epidermidis. Conclusion In a case of a shunt infection the timely usage of appropriate antibiotics, according to the antimicrobial susceptibility testing, and the removal of the shunt apparatus is essential for successful treatment.
Directory of Open Access Journals (Sweden)
Odilei Rogerio Prado
2013-12-01
Full Text Available The objective was to determine the effect of feeding system and time of the year on the in vivo and carcass characteristics of lambs slaughtered at the Cooperative Cooperaliança (Guarapuava-PR. Ile de France lambs and their crossbreds (n=253 were evaluated at slaughter with 39.6 kg of mean body weight in three periods between April and September 2010. Four feeding systems for finishing of lambs were identified: a grazing dams + lambs with creep-feeding for lambs (n=67; b no supplemented, grazing dams + lambs (n=47; c grazing dams + lambs, all of them supplemented with concentrate (n=30; d irregular system of feeding (n=109. Measurements on lambs were carried out in vivo and by ultrasound before slaughter and the carcass measurements were taken before and after chilling. Lambs delivered for slaughter between the end of August and the first half of September showed better results (p <0.05 for muscle development, dressing percentage and fat thickness in the carcass compared to that slaughtered in April and June. It was concluded that the feeding system with supplementation for dams and sucking lambs resulted in better characteristics for body and carcass measurements compared to other systems.
Beyond the periodic orbit theory
Cvitanovic, P; Rolf, J; Vattay, G; Cvitanovic, Predrag; Hansen, Kim; Rolf, Juri; Vattay, Gabor
1997-01-01
The global constraints on chaotic dynamics induced by the analyticity of smooth flows are used to dispense with individual periodic orbits and derive infinite families of exact sum rules for several simple dynamical systems. The associated Fredholm determinants are of particularly simple polynomial form. The theory developed suggests an alternative to the conventional periodic orbit theory approach to determining eigenspectra of transfer operators.
Kupfer, T.; Geier, S.; Heber, U.; Østensen, R. H.; Barlow, B. N.; Maxted, P. F. L.; Heuser, C.; Schaffenroth, V.; Gänsicke, B. T.
2015-04-01
The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding hot subdwarf stars with massive compact companions like massive white dwarfs (M > 1.0 M?), neutron stars, or stellar-mass black holes. The existence of such systems is predicted by binary evolution theory, and recent discoveries indicate that they exist in our Galaxy. We present orbital and atmospheric parameters and put constraints on the nature of the companions of 12 close hot subdwarf B star (sdB) binaries found in the course of the MUCHFUSS project. The systems show periods between 0.14 and 7.4 days. In nine cases the nature of the companions cannot be constrained unambiguously whereas three systems most likely have white dwarf companions. We find that the companion to SDSS J083006.17+475150.3 is likely to be a rare example of a low-mass helium-core white dwarf. SDSS J095101.28+034757.0 shows an excess in the infrared that probably originates from a third companion in a wide orbit, which makes this system the second candidate hierarchical triple system containing an sdB star. SDSS J113241.58-063652.8 is the first helium deficient sdO star with a confirmed close companion. This study brings to 142 the number of sdB binaries with orbital periods of less than 30 days and with measured mass functions. We present an analysis of the minimum companion mass distribution and show that it is bimodal. One peak around 0.1 M? corresponds to the low-mass main sequence (dM) and substellar companions. The other peak around 0.4 M? corresponds to the white dwarf companions. The derived masses for the white dwarf companions are significantly lower than the average mass for single carbon-oxygen white dwarfs. In a Teff - log g diagram of sdB+dM companions, we find signs that the sdB components are more massive than the rest of the sample. The full sample was compared to the known population of extremely low-mass white dwarf binaries as well as short-period white dwarfs with main sequence companions. Both samples show a significantly different companion mass distribution indicating either different selection effects or different evolutionary paths. We identified 16 systems where the dM companion will fill its Roche Lobe within a Hubble time and will evolve into a cataclysmic variable; two of them will have a brown dwarf as donor star. Twelve systems with confirmed white dwarf companions will merge within a Hubble time, two of them having a mass ratio to evolve into a stable AM CVn-type binary and another two which are potential supernova Ia progenitor systems. The remaining eight systems will most likely merge and form RCrB stars or massive C/O white dwarfs depending on the structure of the white dwarf companion. Appendix A is available in electronic form at http://www.aanda.org
International Nuclear Information System (INIS)
The classification of chest alterations in Cystic Fibrosis (CF) and related score proposed by Chrispin and Norman has been widely adopted in Europe and is still applied (although slightly modified) in most European Centres. Brasfield classification instead has been monstly used in the USA. Lately, however, to revise both classifications, the need has been felt, for a more precise correlation to anatomo-radiological data as well as for inclusion of headings which have not been taken into account so far. In 1980 one of the authors (Vichi) worked out a new scoring system for the chest alterations of CF. Results are reported from a follow-up of 15 patients with CF carried out at the FC Center of Meyer Ospedale in Florence from the late 1981 to 1985. The patients underwent periodic checking including determination of clinical scoring system-according to Shwachman and Kulczychi modified by Doershuk-respiratory function tests, chest X-rays evaluated by three radiologists separately, following both Chrispin and Norman and Vichi scoring systems. The latter system has proved to be well correlated to clinical data and to the ordinary pulmonary function tests but it mainly presents a high observer reproducibility
Moutou, C.; Lo Curto, G.; Mayor, M.; Bouchy, F.; Benz, W.; Lovis, C.; Naef, D.; Pepe, F.; Queloz, D.; Santos, N. C.; Ségransan, D.; Sousa, S. G.; Udry, S.
2015-04-01
We describe radial-velocity time series obtained by HARPS on the 3.60 m telescope in La Silla (ESO, Chile) over ten years and report the discovery of five new giant exoplanets in distant orbits; these new planets orbit the stars HD 564, HD 30669, HD 108341, and BD -114672. Their periods range from 492 to 1684 days, semi-major axes range from 1.2 to 2.69 AU, and eccentricities range from 0 to 0.85. Their minimum mass ranges from 0.33 to 3.5 MJup. We also refine the parameters of two planets announced previously around HD 113538, based on a longer series of measurements. The planets have a period of 663 ± 8 and 1818 ± 25 days, orbital eccentricities of 0.14 ± 0.08 and 0.20 ± 0.04, and minimum masses of 0.36 ± 0.04 and 0.93 ± 0.06 MJup. Finally, we report the discovery of a new hot-Jupiter planet around an active star, HD 103720; the planet has a period of 4.5557 ± 0.0001 days and a minimum mass of 0.62 ± 0.025 MJup. We discuss the fundamental parameters of these systems and limitations due to stellar activity in quiet stars with typical 2 m s-1 radial velocity precision. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope at La Silla (Chile), under the GTO program ID 072.C-0488, 183.C-0972 and the regular programs: 085.C-0019, 087.C-0831, 089.C-0732, 090.C-0421, 091.C-0034, and 092.C-0721.Figures 8 and 9 and Tables 4-9 are available in electronic form at http://www.aanda.org
International Nuclear Information System (INIS)
We investigate numerically the effects of time delay on the phenomenon of noise-enhanced stability (NES) in a periodically modulated bistable system. Three types of time-delayed feedback, including linear delayed feedback, nonlinear delayed feedback and global delayed feedback, are considered. We find a non-monotonic behaviour of the mean first-passage time (MFPT) as a function of the delay time ?, with a maximum in the case of linear delayed feedback and with a minimum in the case of nonlinear delayed feedback. There are two peculiar values of ? around which the NES phenomenon is enhanced or weakened. For the case of global delayed feedback, the increase of ? always weakens the NES phenomenon. Moreover, we also show that the amplitude A and the frequency ? of the periodic forcing play an opposite role in the NES phenomenon, i.e. the increase of A weakens the NES effect while the increase of ? enhances it. These observations demonstrate that the time-delayed feedback can be used as a feasible control scheme for the NES phenomenon
Scientific Electronic Library Online (English)
Néstor Alonso, Arias-Hernández; Martha Lucía, Molina-Prado; Jaime Enrique, Meneses-Fonseca.
2015-04-01
Full Text Available En este trabajo se presenta un método para extraer información 3D usando un microscopio interferométrico, sin la necesidad de utilizar un dispositivo transductor piezoeléctrico (PZT, por su siglas en inglés). En lugar de ello se utiliza un sistema de posicionamiento que aprovecha la sensibilidad a l [...] a fase de una mira periódica, que es registrada mediante el uso de un sistema de visión. El procesamiento de la mira permite calcular la distancia relativa entre el objetivo Mirau y el objeto. Reconstrucciones topográficas de algunas décimas de milímetros fueron calculadas con una precisión de aproximadamente 28 nanómetros. Se presenta un análisis teórico y algunos resultados experimentales. Abstract in english A method to extract 3D information using a white light interferometer without using PZT is presented. Instead a positioning system that uses the phase sensitivity of a target periodic is employed. The image treatment realized on the periodic target permits to calculate the relative distance between [...] Mirau objective and object surface. Topographic reconstructions of objects with dimensions of some tenths of millimeters were calculated with an accuracy of approximately 28 nanometers. Theoretical analysis and experimental results are shown.
Gandolfo, Sergio; BROCCOLETTI, Roberto
2007-01-01
AIM: To analyze the data collected in 13 years of clinical controls in patients with oral rehabilitation on Bone System dental implant systems and to evaluate the success, failure and complications in daily implant dentistry, without strict inclusion criteria, in order to define the success or survival or failure of dental implants. METHODS: A total of 477 patients (231 men and 246 women) received dental implants for oral rehabilitation in 3 different private dental offices in Piedmont, Italy...