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1

Heat-resistant metals in Mendeleev's periodic table  

Science.gov (United States)

The data from the Inorganic Crystal Structure Database (ICSD, version 1.7.1, 2010-2) on refractory elements of Mendeleev's periodic table have been analyzed. Insight is gained into the current state of structural studies of simple materials, the number of polymorphs, and their symmetry.

Podberezskaya, N. V.

2012-11-01

2

Evidence for Energy Regularity in the Mendeleev Periodic Table  

CERN Multimedia

We show that the dependence of the total energy of the atoms on their atomic number follows a q-exponential (proposed by Tsallis), for all elements of the periodic table. The result is qualitatively explained in terms of the way the atomic configurations are arranged to minimize energy.

Amador, Cassio H S

2008-01-01

3

The comparison of element composition of Venus, Earth, Mars, and chondrites in the light of the Mendeleev Periodic Law  

International Nuclear Information System (INIS)

[en] The share of free neutral atoms, N0, for all elements in Protoplanet nebula has been determined with the account of their abundance and physico-chemical properties. The linear dependence for the ratio of nonvolatile and volatile elements in chondrites and igneous rocks of the Earth on N0 was obtained. The Mendeleev Periodic Law was used to obtain the proof of the existence of the hypothetical process of element magnetic separation in Protoplanet nebula. To this end the concentration ratios of element-analogous with different N0 in the matters of Venus, Earth, Mars, and chondrites were compared. The data obtained are sufficient demonstration of the existence of the hypothetical process of element magnetic separation in Protoplanet nebula. With the account of the above said, it was shown that Shergotty and Tunguska meteorites by their relative elemental composition are close to Mars and asteroids, respectively. (author)

1998-01-01

4

The slow penetration of the Mendeleev Table in the French school curricula  

International Nuclear Information System (INIS)

[en] 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.)

2012-01-01

5

Periodic system and strength characteristics of the elements. Perio dicheskaya sistema d. i. mendeleeva i silovye kharakteristikt elementov  

Energy Technology Data Exchange (ETDEWEB)

An critical examination is made of the principles underlying the placement of the elements in the D.I. Mendeleev periodic system. A detailed study is made of the main, internal, secondary, and dual periodicity. An analysis is made of changes in orbital radii, ionization potentials, electron affinity, and strength characteristics of valent electrons with respect to atomic number. New forms of the system are proposed on whose basis an analysis is made of similarities and differences in the properties of elements within the subgroups and lateral positions of the short form of the Mendeleev chart. The work is designed for researchers working in mineralogy, geochemistry, chemisty, crystallochemistry, material studies, allied sciences, university- level instructors, graduate and undergraduate students. The book might also be useful to secondary school teachers and senior students. 150 references, 15 tables, 14 figures.

Godovikov, A.A.

1981-01-01

6

XVIII Mendeleev congress on general and applied chemistry. Summaries of reports in five volumes. Volume 5. IV Russian-French symposium Supramolecular systems in chemistry and biology. II Russian-Indian symposium on organic chemistry. International symposium on present-day radiochemistry Radiochemistry: progress and prospects. International symposium Green chemistry, stable evolution and social responsibility of chemists. Symposium Nucleophilic hydrogen substitution in aromatic systems and related reactions  

International Nuclear Information System (INIS)

The 5 volume of the XVIII Mendeleev congress on general and applied chemistry includes summaries of reports on the subjects of sypramolecular systems in chemistry and biology, organic chemistry, modern radiochemistry, green chemistry - development and social responsibility of chemists, nucleophilic hydrogen substitution in aromatic systems and related chemical reactions

2007-01-01

7

Contrasting glacial/interglacial regimes in the western Arctic Ocean as exemplified by a sedimentary record from the Mendeleev Ridge  

Science.gov (United States)

Distinct cyclicity in lithology and microfaunal distribution in sediment cores from the Mendeleev Ridge in the western Arctic Ocean (water depths ca. 1. 5 km) reflects contrasting glacial/interglacial sedimentary patterns. We conclude that during major glaciations extremely thick pack ice or ice shelves covered the western Arctic Ocean and its circulation was restricted in comparison with interglacial, modern-type conditions. Glacier collapse events are marked in sediment cores by increased contents of ice-rafted debris, notably by spikes of detrital carbonates and iron oxide grains from the Canadian Arctic Archipelago. Composition of foraminiferal calcite ?? 18O and ??13C also shows strong cyclicity indicating changes in freshwater balance and/or ventilation rates of the Arctic Ocean. Light stable isotopic spikes characterize deglacial events such as the last deglaciation at ca. 12 14C kyr BP. The prolonged period with low ??18O and ??13C values and elevated contents of iron oxide grains from the Canadian Archipelago in the lower part of the Mendeleev Ridge record is interpreted to signify the pooling of freshwater in the Amerasia Basin, possibly in relation to an extended glaciation in arctic North America. Unique benthic foraminiferal events provide a means for an independent stratigraphic correlation of sedimentary records from the Mendeleev Ridge and other mid-depth locations throughout the Arctic Ocean such as the Northwind and Lomonosov Ridges. This correlation demonstrates the disparity of existing age models and underscores the need to establish a definitive chronostratigraphy for Arctic Ocean sediments. ?? 2003 Elsevier B.V. All rights reserved.

Polyak, L.; Curry, W. B.; Darby, D. A.; Bischof, J.; Cronin, T. M.

2004-01-01

8

Late Quaternary Paleoceanography of the Mendeleev Ridge, Central Arctic Ocean: Planktonic Foraminiferal Composition and Stable Isotopy  

Science.gov (United States)

Mendeleev Ridge is located between the two major circulation systems of the Arctic Ocean, the Beaufort Gyre and the Transpolar Drift, thus offering a valuable sedimentary archive for investigating paleoceanographic changes. We perform a detailed investigation of a HOTRAX05 sediment core HLY0503-08JPC (79°35.6'N, 172°30.1'W, 2792 mwd, length 12m) from the Mendeleev Ridge flank that provides millennial to century scale resolution for upper Quaternary sediments. The core has been logged for VIS Diffuse Spectral Reflectance and XRF, u-channeled for paleomagnetic analyses and coninutously sampled at 1cm sample width. The washed >63um sediment fraction is being analyzed for planktonic foraminiferal content and stable isotopic composition. Age constraint for the upper Quaternary record is provided by AMS 14C dates and Amino Acid Racemization measurements from foraminiferal adundance maxima, as well as correlation with established Arctic Ocean stratigraphies. The brown, faunal rich intervals in the upper to middle Quaternary record correspond to interglacials when the influence of circum-arctic ice sheets on processes in the Arctic Ocean was minimal. Grayish, faunal poor intervals reflect glacial/deglacial environments characterized by discharge of icebergs and meltwater. The later part of the LGM contains a pronounced hiatus, possibly related to the ice cover over the basin at that time. We infer that earlier glaciations may also contain hiatuses, which should result in uneven sedimentation rates. Brown intervals are characterized by high biogenic sediment and high stable isotope values in planktonic foraminiferal tests, especially d13C. We presume that these features are related to better ventilation of the halocline from the continental margins at higher sea levels and less ice cover. d18O record displays prominent minima within glacial intervals, which, together with IRD spikes, indicate discharges of icebergs and meltwater from ice sheets at the Arctic periphery. In particular, sharp d18O minima in the penultimate glacial unit probably represent pulsed drainage of proglacial lakes in Eurasia.

Adler, R.; Polyak, L.; Ortiz, J.; Grottoli, A.; Kaufman, D.

2007-12-01

9

Availability of periodically tested systems  

International Nuclear Information System (INIS)

There is at the present time a need in accurate models to asess the availability of periodically tested stand-by systems. This paper shows how to improve the well known 'saw-tooth curve' model in order to take into account various reliability parameters. A model is developed to assess the pointwise and the mean availabilities of periodically tested stand-by systems. Exact and approxination formulae are given. In addition, the model developed herein leads to optimize the test interval in order to minimize the mean unavailability. A safety diesel in a nuclear power plant is given as an example

1979-03-30

10

Fractional-period excitations in continuum periodic systems  

International Nuclear Information System (INIS)

We investigate the generation of fractional-period states in continuum periodic systems. As an example, we consider a Bose-Einstein condensate confined in an optical-lattice potential. We show that when the potential is turned on nonadiabatically, the system explores a number of transient states whose periodicity is a fraction of that of the lattice. We illustrate the origin of fractional-period states analytically by treating them as resonant states of a parametrically forced Duffing oscillator and discuss their transient nature and potential observability.

2006-01-01

11

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.

2005-01-17

12

The Periodic Response of Periodically Perturbated Stochastic Systems  

CERN Document Server

The paper introduces a new numerical characteristic of one dimensionalstochastic systems. This quantity is a measure of minimal periodicity, can bedetected in the process deep differential structure. The claim is that this newmeasure of stochasticity is also a well adapted characteristic for research ofstochastic resonance phenomena.

Shahverdian, A Y

2000-01-01

13

Periodic solutions for planar autonomous systems with nonsmooth periodic perturbations  

CERN Multimedia

In this paper we consider a class of planar autonomous systems having an isolated limit cycle x_0 of smallest period T>0 such that the associated linearized system around it has only one characteristic multiplier with absolute value 1. We consider two functions, defined by means of the eigenfunctions of the adjoint of the linearized system, and we formulate conditions in terms of them in order to have the existence of two geometrically distinct families of T-periodic solutions of the autonomous system when it is perturbed by nonsmooth T-periodic nonlinear terms of small amplitude. We also show the convergence of these periodic solutions to x_0 as the perturbation disappears and we provide an estimation of the rate of convergence. The employed methods are mainly based on the theory of topological degree and its properties that allow less regularity on the data than that required by the approach, commonly employed in the existing literature on this subject, based on various versions of the implicit function the...

Makarenkov, Oleg

2007-01-01

14

Small parameter perturbations of nonlinear periodic systems  

CERN Document Server

In this paper we consider a class of nonlinear periodic differential systems perturbed by two nonlinear periodic terms with multiplicative different powers of a small parameter $e>0$. For such a class of systems we provide conditions which guarantee the existence of periodic solutions of given period $T>0$. These conditions are expressed in terms of the behaviour on the boundary of an open bounded set $U$ of $R^n$ of the solutions of suitably defined linearized systems. The approach is based on the classical theory of the topological degree for compact vector fields. An application to the existence of periodic solutions to the van der Pol equation is also presented.

Kamenskii, Mikhail; Nistri, Paolo

2004-01-01

15

Superheavy elements in D I Mendeleev's Periodic Table  

Energy Technology Data Exchange (ETDEWEB)

The results on the synthesis of new superheavy elements, synthesized in complete fusion reactions of {sup 48}Ca 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.

Oganessian, Yury Ts; Dmitriev, Sergey N [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation)

2009-12-31

16

Attractors of the periodically forced Rayleigh system  

Directory of Open Access Journals (Sweden)

Full Text Available The autonomous second order nonlinear ordinary differential equation(ODE) introduced in 1883 by Lord Rayleigh, is the equation whichappears to be the closest to the ODE of the harmonic oscillator withdumping.In this paper we present a numerical study of the periodic andchaotic attractors in the dynamical system associated with the generalized Rayleigh equation. Transition between periodic and quasiperiodic motion is also studied. Numerical results describe the system dynamics changes (in particular bifurcations), when the forcing frequency is varied and thus, periodic, quasiperiodic or chaotic behaviour regions are predicted.

Petre Bazavan

2011-01-01

17

General Periodic Boundary Value Problem for Systems  

Directory of Open Access Journals (Sweden)

Full Text Available The paper deals with the existence of nonzero periodic solution of systems, where k?(0, ?/T), ?, ? are n×n real nonsingular matrices, ?=(?1…?n), f(t, u)=(f1(t, u),…,fn(t, u))?C([0, T]×?n+,?+) is periodic of period T in the t variable are continuous and nonnegative functions. We determine the Green’s function and prove that the existence of nonzero periodic positive solutions if one of . In addition, if all i=?1…n?where ?1 is the principle eigenvalues of the corresponding linear systems. The proof based on the fixed point index theorem in cones. Application of our result is given to such systems with specific nonlinearities.

Mohammed Elnagi

2012-01-01

18

Late Pleistocene sediment provenance on the Mendeleev Ridge, Arctic Ocean, from XRF Elemental Analysis and Diffuse Spectral Reflectance measurements  

Science.gov (United States)

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.

Ortiz, J. D.; Polyak, L.; Adler, R.; Jakobsson, M.; Darby, D.

2007-12-01

19

Design of periodic beam-transport systems  

Energy Technology Data Exchange (ETDEWEB)

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.

Farrell, J.A.

1983-01-01

20

Periodically driven quantum open systems: Tutorial  

CERN Document Server

We present a short derivation and discussion of the master equation for an open quantum system weakly coupled to a heat bath and then its generalization to the case of with periodic external driving based on the Floquet theory. Further, a single heat bath is replaced by several ones. We present also the definition of heat currents which satisfies the second law of thermodynamics and apply the general results to a simple model of periodically modulated qubit.

Alicki, Robert; Kurizki, Gershon

2012-01-01

 
 
 
 
21

Periodic Orbits and Escapes in Dynamical Systems  

CERN Document Server

We study the periodic orbits and the escapes in two different dynamical systems, namely (1) a classical system of two coupled oscillators, and (2) the Manko-Novikov metric (1992) which is a perturbation of the Kerr metric (a general relativistic system). We find their simple periodic orbits, their characteristics and their stability. Then we find their ordered and chaotic domains. As the energy goes beyond the escape energy, most chaotic orbits escape. In the first case we consider escapes to infinity, while in the second case we emphasize escapes to the central "bumpy" black hole. When the energy reaches its escape value a particular family of periodic orbits reaches an infinite period and then the family disappears (the orbit escapes). As this family approaches termination it undergoes an infinity of equal period and double period bifurcations at transitions from stability to instability and vice versa. The bifurcating families continue to exist beyond the escape energy. We study the forms of the phase spac...

Contopoulos, George; Lukes-Gerakopoulos, Georgios

2012-01-01

22

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.

2008-01-01

23

Activated escape of periodically modulated systems  

CERN Document Server

The rate of noise-induced escape from a metastable state of a periodically modulated overdamped system is found for an arbitrary modulation amplitude $A$. The instantaneous escape rate displays peaks that vary with the modulation from Gaussian to strongly asymmetric. The prefactor $\

Dykman, M I

2005-01-01

24

On periodic solutions of superquadratic Hamiltonian systems  

Directory of Open Access Journals (Sweden)

Full Text Available We study the existence of periodic solutions for some Hamiltonian systems $dot z=JH_{z}(t,z)$ under new superquadratic conditions which cover the case $H(t,z)=|z|^{2}(ln (1+|z|^{p}))^q $ with $p, q>1$. By using the linking theorem, we obtain some new results.

Guihua Fei

2002-01-01

25

Activated escape of periodically driven systems  

CERN Multimedia

We discuss activated escape from a metastable state of a system driven by a time-periodic force. We show that the escape probabilities can be changed very strongly even by a comparatively weak force. In a broad parameter range, the activation energy of escape depends linearly on the force amplitude. This dependence is described by the logarithmic susceptibility, which is analyzed theoretically and through analog and digital simulations. A closed-form explicit expression for the escape rate of an overdamped Brownian particle is presented and shown to be in quantitative agreement with the simulations. We also describe experiments on a Brownian particle optically trapped in a double-well potential. A suitable periodic modulation of the optical intensity breaks the spatio-temporal symmetry of an otherwise spatially symmetric system. This has allowed us to localize a particle in one of the symmetric wells.

Dykman, M I; McCann, L I; Smelyanskiy, V N; Luchinsky, D G; Mannella, R; McClintock, P V E

2001-01-01

26

Periodic Solutions for Highly Nonlinear Oscillation Systems  

DEFF Research Database (Denmark)

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.

Ghadimi, M; Barari, Amin

2012-01-01

27

Matrix methods in periodic focusing systems  

Energy Technology Data Exchange (ETDEWEB)

A linear differential equation with periodic driving matrix P in the n-dimensional phase space, the matrizant R(P) of this equation and an envelope matrix {sigma}, representing the simultaneous transmission of an ensemble of trajectories, are considered. Three new nxn matrices are introduced: the oscillating antisymmetric matrix, the amplitude matrix and the phase orthogonal matrix, elements of which are derived as functions of the envelope and the driving matrices. The Courant-Snyder parametrization for n=2 in periodic systems is generalized to an arbitrary n. The generalized multiplicative representation of the matrizant R(P) is derived via the amplitude and phase matrices. For the particular case n=2 the Courant-Snyder representation is obtained.

Dymnikov, Alexander D. E-mail: ad455@columbia.edu

1999-05-01

28

Alguns aspectos históricos da classificação periódica dos elementos químicos Some historical aspects of the periodic classification of the chemical elements  

Directory of Open Access Journals (Sweden)

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.

Mario Tolentino; Romeu C. Rocha-Filho; Aécio Pereira Chagas

1997-01-01

29

Periodic Table of the Elements in the Perspective of Artificial Neural Networks  

Science.gov (United States)

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…

Lemes, Mauricio R.; Dal Pino, Arnaldo

2011-01-01

30

On the behavior of periodic solutions of planar autonomous Hamiltonian systems with multivalued periodic perturbations  

CERN Multimedia

Aim of the paper is to provide a method to analyze the behavior of $T$-periodic solutions $x_\\eps, \\eps>0$, of a perturbed planar Hamiltonian system near a cycle $x_0$, of smallest period $T$, of the unperturbed system. The perturbation is represented by a $T$-periodic multivalued map which vanishes as $\\eps\\to0$. In several problems from nonsmooth mechanical systems this multivalued perturbation comes from the Filippov regularization of a nonlinear discontinuous $T$-periodic term. \

Makarenkov, Oleg; Nistri, Paolo

2010-01-01

31

Estimates on the minimal period for periodic solutions of nonlinear second order Hamiltonian systems  

International Nuclear Information System (INIS)

[en] In this paper, we prove a sharper estimate on the minimal period for periodic solutions of autonomous second order Hamiltonian systems under precisely Rabinowitz' superquadratic condition. (author). 20 refs, 1 fig

1994-01-01

32

Nonlinear Stability for the Periodic and Non-Periodic Zakharov System  

CERN Document Server

We prove the existence of a smooth curve of periodic traveling wave solutions for the Zakharov system. We also show that this type of solutions are nonlinear stable by the periodic flow generated for the system mentioned before. An improvement of the work of Ya Ping is made, we prove the stability of the solitary wave solutions associated to the Zakharov system.

Angulo, Jaime

2010-01-01

33

On positive periodic solution of periodic competition Lotka-Volterra system with time delay and diffusion  

Energy Technology Data Exchange (ETDEWEB)

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.

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

34

On positive periodic solution of periodic competition Lotka-Volterra system with time delay and diffusion  

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.

2007-01-01

35

Holistic Approach to the Periodic System of Elements  

CERN Document Server

For studying the objectivity and the quality of a given form of the Periodic system as a single whole we compare plots of functions presenting properties of elements in pairs of periods. Using mathematical statistics we introduce a dimensionless parameter which indicates high quality of the long form of the Periodic system.

Trunov, N N

2009-01-01

36

Problem of unusual valent states of f-elements in relation to D.I. Mendeleev periodical law  

International Nuclear Information System (INIS)

[en] A question of participation of inner 6p-atomic orbitals in the formation of chemical bond and expansion of valency possibilities of actinides at the expense of it is discussed. The forecasting of new valency forms for actinides puts a question of their possible similarity with lantanides. It is shown that the similarity is of a ''cross'' character, and it is explained by cymbate change of excitation energy from fsup(n) to fsup(n-1)d-electron states. In the first half of lanthanides 4f-electron levels are more stable than in the second one, whereas in actinides in the first half 5f-levels are less stable than in the second one. Such similarity will be manifested in all properties, which are conditioned by partial participation in the formation of bonds of d-atomic orbitals. In the limiting case of ion configurations of fsup(n) tetrade effect should be manifested, which is conditioned by the fact that quantum numbers of complete orbital momentum are symmetric as to electron configurations of f3(f10) and f4(f11). It will be manifested in all the properties, which are determined by the diffusion of f-orbitals

1982-01-01

37

Periodic steady regime and interference in a periodically driven quantum system.  

UK PubMed Central (United Kingdom)

We study the coherent dynamics of a quantum many-body system subject to a time-periodic driving. We argue that in many cases, destructive interference in time makes most of the quantum averages time periodic, after an initial transient. We discuss in detail the case of a quantum Ising chain periodically driven across the critical point, finding that, as a result of quantum coherence, the system never reaches an infinite temperature state. Floquet resonance effects are moreover observed in the frequency dependence of the various observables, which display a sequence of well-defined peaks or dips. Extensions to nonintegrable systems are discussed.

Russomanno A; Silva A; Santoro GE

2012-12-01

38

Periodic Steady Regime and Interference in a Periodically Driven Quantum System  

Science.gov (United States)

We study the coherent dynamics of a quantum many-body system subject to a time-periodic driving. We argue that in many cases, destructive interference in time makes most of the quantum averages time periodic, after an initial transient. We discuss in detail the case of a quantum Ising chain periodically driven across the critical point, finding that, as a result of quantum coherence, the system never reaches an infinite temperature state. Floquet resonance effects are moreover observed in the frequency dependence of the various observables, which display a sequence of well-defined peaks or dips. Extensions to nonintegrable systems are discussed.

Russomanno, Angelo; Silva, Alessandro; Santoro, Giuseppe E.

2012-12-01

39

Fundamental cycle of a periodic box-ball system  

International Nuclear Information System (INIS)

We investigate a box-ball system with periodic boundary conditions. Since the box-ball system is a deterministic dynamical system that takes only a finite number of states, it will exhibit periodic motion. We determine its fundamental cycle for a given initial state

2003-01-10

40

Existence of periodic solutions of impulsive differential systems  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, the existence of periodic solutions of impulsive differential systems is considered. Since the solutions of such a system are peicewise continuous, it is necessary to introduce piecewise continuous Lyapunov functions. By means of such functions, together with the comparison principle, some sufficient conditions for the existence of periodic solutions of impulsive differential systems are established.

L. H. Erbe; Xinzhi Liu

1991-01-01

 
 
 
 
41

Stability, Resonance and Lyapunov Inequalities for Periodic Conservative Systems  

CERN Multimedia

This paper is devoted to the study of Lyapunov type inequalities for periodic conservative systems. The main results are derived from a previous analysis which relates the best Lyapunov constants to some especial (constrained or unconstrained) minimization problems. We provide some new results on the existence and uniqueness of solutions of nonlinear resonant and periodic systems. Finally, we present some new conditions which guarantee the stable boundedness of linear periodic conservative systems.

Canada, Antonio

2010-01-01

42

Periodic solutions of periodically perturbed planar autonomous systems: A topological approach  

CERN Multimedia

Aim of this paper is to investigate the existence of periodic solutions of a nonlinear planar autonomous system having a limit cycle x_0 of least period T_0>0 when it is perturbed by a small parameter, T_1-periodic, perturbation. In the case when T_0/T_1 is a rational number l/k, with l, k prime numbers, we provide conditions to guarantee, for the parameter perturbation e>0 sufficiently small, the existence of klT_0-periodic solutions x_e of the perturbed system which converge to the trajectory x_1 of the limit cycle as e->0. Moreover, we state conditions under which T=klT_0 is the least period of the periodic solutions x_e. We also suggest a simple criterion which ensures that these conditions are verified. Finally, in the case when T_0/T_1 is an irrational number we show the nonexistence, whenever T>0 and e>0, of T-periodic solutions x_e of the perturbed system converging to x_1. The employed methods are based on the topological degree theory.

Kamenskii, Mikhail; Nistri, Paolo

2006-01-01

43

Analysis of Periodic Discrete Event Systems in (Max,+) Algebra  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Discrete Event Dynamic Systems modeled by (max,+) linear equations with periodically varying coefficients are studied. It turns out that spectral properties of the so-called monodromy matrix can be used for the performance evaluation of these systems.

Lahaye, Sébastien; Boimond, Jean-Louis; Hardouin, Laurent

44

Late Quaternary history of circum-Arctic ice sheets and Arctic Ocean paleoceanography: New insights from a sediment core transect across Mendeleev Ridge  

Science.gov (United States)

The Arctic Ocean plays an important role in the global climate system. However, due to the major technological and/or logistical problems in reaching this permanently ice-covered region and in retrieving long and undisturbed sediment cores, the knowledge of its short and long term paleoceanographic and paleoclimatic history is still limited. More well-dated and detailed records are needed to study the late Quaternary history of circum-Arctic ice sheets and its relationship to the paleoceanographic circulation pattern in the central Arctic Ocean. In this context, our research is aiming to answer the following key questions: (1) Were extensive late Quaternary circum-Arctic ice sheets developed synchronously or asynchronously in North America, East Siberia, and Eurasia? (2) How is the evolution of circum-Arctic ice sheets related to the paleoceanographic circulation patterns in the central Arctic Ocean, i.e., how did the major surface-water current systems (Beaufort Gyre and Transpolar Drift) evolve and change their extension? For this research project, new sediment cores were recovered during the RV "Polarstern" ARK-XXIII/3 expedition (August-October 2008) along two transects from the Canada Basin across the central Mendeleev Ridge towards the Makarov Basin and the Lomonosov Ridge in the Eurasian Arctic (for background see Stein et al., 2010). Here, we mainly focus on the northern transect along 80°30'N. In all studied sediment cores, Clark's standard lithological units A to M (Clark et al, 1980) could be clearly identified, and the prominent pink-white layers and more sandy intervals are the key sedimentary characteristics used for core correlation and development of a preliminary age model (Stein et al, 2010). According to this age model, the first onset of coarse-grained dolomite-rich material probably occurred during MIS 16. In general, MIS 16, 12, 10, and 8 are characterized by increased dolomite contents and high amount of sand (>63?m) indicating ice-rafted debris (IRD) input from the Laurentide Ice Sheet (LIS). MIS 6, on the other hand, is characterized by low dolomite and high quartz contents, suggesting a different source region for the IRD input. In this poster, new XRD and grain-size data from the coarse-grained intervals related to major glaciations, are presented. These data allow a more detailed reconstruction of past Quaternary glaciations in North America, Siberia, and Eurasia.

Zou, H.; Schulte-Loh, I.; Bazhenova, E.; Stein, R.; Matthiessen, J.; Vogt, C.

2012-04-01

45

Changes in terrestrial organic matter input to the Mendeleev Ridge, western Arctic Ocean, during the Late Quaternary  

Science.gov (United States)

Hydrocarbons and glycerol dialkyl glycerol tetraethers (GDGTs) were analyzed in Late Pleistocene sediments of Core HLY0503-08JPC collected at the Mendeleev Ridge during the Healy-Oden Trans Arctic Expedition 2005 (HOTRAX"05) to investigate environmental changes in the western Arctic Ocean during the last full glacial cycle, ca. 130 kyr. Variations in long-chain n-alkane and GDGT concentrations correspond to alternated color banding, brown (interglacial/interstadial) and grayish (glacial/stadial) layers. Grayish layers are characterized by abundant higher plant n-alkanes and branched GDGTs, implying larger contribution of terrestrial plant and soil organic matter (OM) in glacial environments, possibly due to the deposition of fine-grained products of glacial erosion in the Amerasian basin. Concentration of lithic n- alkanes derived from mature OM, reflected as carbon preference index (CPI) reversely, shows sixteen major maximal peaks mainly at the boundary between grayish and brown layers. Some peaks are correlated to events of iceberg discharge and freshwater outbursts from proglacial lakes of the Eurasian and, possibly, Laurentide ice sheets, suggesting that other peaks may correspond to similar events.

Yamamoto, M.; Polyak, L.

2008-12-01

46

Periodic solutions for Hamiltonian systems in a nonconvex potential well  

International Nuclear Information System (INIS)

Recently there has been a considerable amount of work on the existence of T-periodic solutions for Hamiltonian systems with singular potentials. In this paper the existence of T-periodic solutions for non-conservative second-order dynamical systems in a nonconvex potential well is studied. 20 refs

1989-01-01

47

Controlling chaos with periodic parametric perturbations in Lorenz system  

Energy Technology Data Exchange (ETDEWEB)

Using periodic parametric perturbation to control chaos in Lorenz system will be finished in this paper. Based on the chaotic perturbation criteria-Melnikov method, a appropriate parametric condition for controlling chaos will be given out, which guide the system from chaotic motion to low-periodic motion. Some results of the numerical simulation are also explained clearly by rigorous analysis.

Wu Zhengmao [Department of Automation, Shanghai Jiaotong University, 800 Dong Chuan Road, Class A0303291, Shanghai 200030 (China)]. E-mail: zhengmaowu@sjtu.edu.cn; Xie Jianying [Department of Automation, Shanghai Jiaotong University, 800 Dong Chuan Road, Class A0303291, Shanghai 200030 (China); Fang Yanyan [Department of Art and Design, Shanghai University of Engineering Science, Shanghai 200336 (China); Xu Zhenyuan [School of Science, Southern Yangtze University, Jiangsu Wuxi 214036 (China)

2007-04-15

48

Controlling chaos with periodic parametric perturbations in Lorenz system  

International Nuclear Information System (INIS)

Using periodic parametric perturbation to control chaos in Lorenz system will be finished in this paper. Based on the chaotic perturbation criteria-Melnikov method, a appropriate parametric condition for controlling chaos will be given out, which guide the system from chaotic motion to low-periodic motion. Some results of the numerical simulation are also explained clearly by rigorous analysis.

2007-01-01

49

Optimization of maintenance periodicity of complex of NPP safety systems  

International Nuclear Information System (INIS)

The analysis of the positive and negative aspects connected to maintenance of the safety systems equipment which basically is in a standby state is executed. Tests of systems provide elimination of the latent failures and raise their reliability. Poor quality of carrying out the tests can be a source of the subsequent failures. Therefore excess frequency of tests can result in reducing reliability of safety systems. The method of optimization of maintenance periodicity of the equipment taking into account factors of its reliability and restoration procedures quality is submitted. The unavailability factor is used as a criterion of optimization of maintenance periodicity. It is offered to use parameters of reliability of the equipment and each of safety systems of NPPs received at developing PSA. And it is offered to carry out the concordance of maintenance periodicity of systems within the NPP maintenance program taking into account a significance factor of the system received on the basis of the contribution of system in CDF. Basing on the submitted method the small computer code is developed. This code allows to calculate reliability factors of a separate safety system and to determine optimum maintenance periodicity of its equipment. Optimization of maintenance periodicity of a complex of safety systems is stipulated also. As an example results of optimization of maintenance periodicity at Zaporizhzhya NPP are presented. (author)

2006-01-01

50

Optimum time between periodic test and maintenance for redundant systems  

International Nuclear Information System (INIS)

A model for analysis of the optimum time between periodic test and maintenance for redundant systems is provided. Conditions when this optimum time exists are analyzed. The optimum time is based on safety considerations, maintenance and repair costs, or total operating costs. Time between periodic test and maintenance is of great significance for safety and cost of operation of redundant systems. If the time between periodic test and maintenance is too large, then deterioration of the equipment may reduce safety and increase economic risk due to potential forced outages. If the period of time between periodic test and maintenance is too short, then safety will be reduced again because of the increase of unavailability due to frequent scheduled outages. Operating costs will also increase. In this paper the mathematical model for optimizing the time between periodic test and maintenance from the standpoint of safety and operational costs is developed

1985-01-01

51

Periodic solutions of nonautonomous differential systems modeling obesity population  

Energy Technology Data Exchange (ETDEWEB)

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.

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

52

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)

1987-01-01

53

Periodic solutions for a class of singulary perturbated systems  

CERN Document Server

In this paper we provide conditions to ensure the existence, for $e>0$ sufficiently small, of periodic solutions of given period $T>0$ in a prescribed domain $U$ for a class of singularly perturbed first order differential systems. Here $e>0$ is the perturbation parameter. Our approach, based on the topological degree theory and the averaging theory, permits to weaken the conditions in [K.R. Schneider, Vibrational control of singularly perturbed systems, in "Lectures Notes in Control and Information Science", 259, 397-408, Springer, London, 2001, Theorem 2] under which the existence of periodic solutions is proved.

Kamenskii, Mikhail; Nistri, Paolo

2004-01-01

54

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.

2008-01-01

55

Mechanism of extraction 4th period of periodic system metal ions with carboxylic acids in sulphate systems  

International Nuclear Information System (INIS)

Extraction of transition metal ions of the 4th period of Periodic system by carboxylic acids in sulfate systems was studied. It is shown that depending on composition and physicochemical properties of aqueous phase (pH, the type of metal ion, its complexing properties etc.) the solvent extraction may proceed according to two mechanisms: cation-exchange or hydration-solvation. The extraction is more effective in the field of cation-exchange mechanism

1988-01-01

56

Applying Adjacent Hyperbolas to Calculation of the Upper Limit of the Periodic Table of Elements, with Use of Rhodium  

Directory of Open Access Journals (Sweden)

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).

Khazan A.

2011-01-01

57

Bifurcations, Period doubling and chaos in clarinet-like systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Wind instruments provide interesting hydrodynamical systems where non-linearities are important but well localized. A simple analysis shows that these systems should undergo Feignebaum-type route to chaos, with a cascade of period doublings. Experiments have been performed fo confirm these predictio...

Maganza, Christian; Caussé, René; Laloë, Franck

58

Infinitely Many Periodic Solutions for Variable Exponent Systems  

Directory of Open Access Journals (Sweden)

Full Text Available We mainly consider the system ??p(x)u=f(v)+h(u) in ?, ??q(x)v=g(u)+?(v) in ?, where 1periodic functions, and ??p(x)u=?(|u?|p(x)?2u?)? is called p(x)-Laplacian. We give the existence of infinitely many periodic solutions under some conditions.

Xiaoli Guo; Mingxin Lu; Qihu Zhang

2009-01-01

59

Pathways of activated escape in periodically modulated systems  

CERN Document Server

We investigate dynamics of activated escape in periodically modulated systems. The trajectories followed in escape form diffusion broadened tubes, which are periodically repeated in time. We show that these tubes can be directly observed and find their shape. Quantitatively, the tubes are characterized by the distribution of trajectories that, after escape, pass through a given point in phase space for a given modulation phase. This distribution may display several peaks separated by the modulation period. Analytical results agree with the results of simulations of a model Brownian particle in a modulated potential.

Ryvkine, D

2006-01-01

60

A principle of valence and relativistic effects in the light of Mendeleev law  

International Nuclear Information System (INIS)

The influence of relativistic effects on the properties of heavy elements is shown. Using as an example transition d-elements, the role of relativistic effects in the stability of electron configuration of the ground state is studied, a comparison of chemical properties in series and periods is carried out. Special attention is paid to lanthanides and actinides. Importance of relativistic effects in the stability of valence forms, in changes of oxidation potentials, in existence of new oxidation rates is pointed out.

1984-01-01

 
 
 
 
61

Gastrointestinal system obstructuions in neonatal period-I  

Directory of Open Access Journals (Sweden)

Full Text Available The suspect of gasrointestinal system obstructions rises in the prenatal period and confirmation and diagnosis are made postnatally. Thorough questioning of gestational period of a pregnant mother gives some clues in terms of gastrointestinal system obstructions. Anamnesis indicating the presence of a congenital defect in the family or relatives would lead to more careful examination of the child. Polyhydramniosis is an indication requiring special attention almost everytime. Five to ten percent of the infants born from the mother with polyhydramniosis have gastrointestinal system obstructions. Inspection and physical exam,following the birth (in the postnatal period) is sufficient in diagnosis and even planning the treatment for the 90% of the patients. (Turk Arch Ped 2010; 45 Suppl: 35-7)

Ergun Erdo?an

2010-01-01

62

Periodic Modulation Induced Increase of Reaction Rates in Autocatalytic Systems  

CERN Document Server

We propose a new mechanism to increase the reactions ratesin multistable autocatalytic systems. The mechanism is based upon the possibility for the enhancement of the response of the system due to the cooperative behavior between the noise and an external periodic modulation. In order to illustrate this feature we compute the reaction velocities for the particular case of the Sel'Kov model, showing that they increase significantly when the periodic modulation is introduced. This behavior originates from the existence of a minimum in the mean first passage time, one of the signatures of stochastic resonance.

Alarcon, T; Rubí, J M

1998-01-01

63

Many-body energy localization transition in periodically driven system  

Science.gov (United States)

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.

D'Alessio, Luca; Polkovnikov, Anatoli

2013-03-01

64

Many-body energy localization transition in periodically driven systems  

Science.gov (United States)

According to the second law of thermodynamics the total entropy of a system is increased during almost any dynamical process. The positivity of the specific heat implies that the entropy increase is associated with heating. This is generally true both at the single particle level, like in the Fermi acceleration mechanism of charged particles reflected by magnetic mirrors, and for complex systems in everyday devices. 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. The dynamical localization is known to occur both at classical (Fermi-Ulam model) and at quantum levels (kicked rotor). 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 both classical and quantum periodically driven ergodic systems in the thermodynamic limit. This phenomenon is reminiscent of many-body localization in energy space.

D'Alessio, Luca; Polkovnikov, Anatoli

2013-06-01

65

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.

1991-01-01

66

Periodic orbits near heteroclinic cycles in a cyclic replicator system.  

UK PubMed Central (United Kingdom)

A species is semelparous if every individual reproduces only once in its life and dies immediately after the reproduction. While the reproduction opportunity is unique per year and the individual's period from birth to reproduction is just n years, the individuals that reproduce in the ith year (modulo n) are called the ith year class, i = 1, 2, . . . , n. The dynamics of the n year-class system can be described by a differential equation system of Lotka-Volterra type. For the case n = 4, there is a heteroclinic cycle on the boundary as shown in previous works. In this paper, we focus on the case n = 4 and show the existence, growth and disappearance of periodic orbits near the heteroclinic cycle, which is a part of the conjecture by Diekmann and van Gils (SIAM J Appl Dyn Syst 8:1160-1189, 2009). By analyzing the Poincaré map near the heteroclinic cycle and introducing a metric to measure the size of the periodic orbit, we show that (i) when the average competitive degree among subpopulations (year classes) in the system is weak, there exists an asymptotically stable periodic orbit near the heteroclinic cycle which is repelling; (ii) the periodic orbit grows in size when some competitive degree increases, and converges to the heteroclinic cycle when the average competitive degree tends to be strong; (iii) when the average competitive degree is strong, there is no periodic orbit near the heteroclinic cycle which becomes asymptotically stable. Our results provide explanations why periodic solutions expand and disappear and why all but one subpopulation go extinct.

Wang Y; Wu H; Ruan S

2012-04-01

67

Universality of the topology of period doubling dynamical systems  

International Nuclear Information System (INIS)

The evolution of the topology of the invariant manifolds of the attractors of 3-D autonomous dynamical systems during period doubling is shown to be universal. The overall topology of the nth attractor is shown to depend only on the topology of the first attractor at birth

1983-01-01

68

Existence and continuation of periodic solutions of Newtonian systems  

CERN Document Server

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. Using the results due to Rabier we show that the Leray-Schauder degree is not applicable in the proofs of our theorems, because it vanishes.

Fura, J

2005-01-01

69

Universality of the topology of period doubling dynamical systems  

Energy Technology Data Exchange (ETDEWEB)

The evolution of the topology of the invariant manifolds of the attractors of 3-D autonomous dynamical systems during period doubling is shown to be universal. The overall topology of the nth attractor is shown to depend only on the topology of the first attractor at birth.

Beiersdorfer, P.

1983-10-01

70

Periodic wavetrains for systems of coupled nonlinear Schrödinger equations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Exact, periodic wavetrains for systems of coupled nonlinear Schrödinger equations are obtained by the Hirota bilinear method and theta functions identities. Both the bright and dark soliton regimes are treated, and the solutions involve products of elliptic functions. The validity of these solutions...

Chow, KW; Lai, DWC

71

Existence of periodic solutions for nonlinear Lienard systems  

Directory of Open Access Journals (Sweden)

Full Text Available We prove the existence and multiplicity of periodic solutions for nonlinear Lienard System of the type x″(t)+ddt[∇F(x(t))]+g(x(t))+h(t,x(t))=e(t) under various conditions upon the functions g, h and e.

Wan Se Kim

1995-01-01

72

Development of Unani system of medicine during Asafjahi period.  

UK PubMed Central (United Kingdom)

During Asafjahi dynasty Unani system of medicine was used extensively. Works of the Persian and Arabian physicians were studied. The medical works were translated in Persian and subsequently in Urdu. Commentaries were written on them and therapeutic investigations of drugs were undertaken. This period produced an enormous number of highly experienced physicians and surgeons. Various Unani Institutions including directorate, hospitals, dispensaries, college and drug stores were established giving tremendous encouragement to this system of medicine.

Shafqat Azmi KA

1995-01-01

73

Energy transduction in periodically driven non-Hermitian systems  

CERN Multimedia

We show a new mechanism to extract energy from non-equilibrium fluctuations typical of periodically driven non-Hermitian systems. The transduction of energy between the driving force and the system is revealed by an \\emph{anomalous} behavior of the susceptibility, leading to a diminution of the dissipated power and consequently to an improvement of the transport properties. The general framework is illustrated by the analysis of some relevant cases.

Alarcon, T; Rubí, J M

2000-01-01

74

Calculation of Coulomb interactions in two-dimensionally periodic systems  

Science.gov (United States)

A generalized implementation is presented of the Lekner method (Lekner, J., 1991, Physica A, 176 , 485) of calculating Coulomb interactions in two-dimensionally periodic systems. The generalized scheme eliminates the restriction on the shape of the primary cell, so it is now applicable to systems with non-rectangular shape. The generalized scheme retains the simplicity of the original method so it is easy to incorporate it into molecular dynamics and Monte Carlo codes. Comparisons are made with two other methods for calculating long range interactions in two-dimensionally periodic systems which are based on a Ewald type approach (Heyes, D. M., Barber, M., and Clarke, J. H. R., 1977, J. chem. Soc. Faraday Trans ii , 73 , 1485; Hautman, J., and Klein, M. L., 1992, Molec. Phys ., 75 , 379). The results show that the generalized Lekner method is superior in terms of accuracy, and that the speed of the new implementation is comparable with the method devised by Hautman and Klein.

Liem, S. Y.; Clarke, J. H. R.

75

The gut mucosal immune system in the neonatal period.  

UK PubMed Central (United Kingdom)

Invasive sepsis in the newborn period is a major cause of childhood morbidity and mortality worldwide. The infant immune system undoubtedly differs intrinsically from the mature adult immune system. Current understanding is that the newborn infant immune system displays a range of competencies and is developing rather than deficient. The infant gut mucosal immune system is complex and displays a plethora of phenotypic and functional irregularities that may be clinically important. Various factors affect and modulate the infant gut mucosal immune system: components of the intestinal barrier, the infant gut microbiome, nutrition and the maternal-infant hybrid immune system. Elucidation of the phenotypic distribution of immune cells, their functional significance and the mucosa-specific pathways used by these cells is essential to the future of research in the field of infant immunology.

Battersby AJ; Gibbons DL

2013-08-01

76

Period Changes of the Algol System SZ Herculis  

Science.gov (United States)

New CCD photometric observations of SZ Her were obtained between February and May 2008. More than 1,100 times of minimum light spanning more than one century were used for the period analysis. We find that the orbital period of SZ Her has varied due to a combination of two periodic variations, with cycle lengths of P3 = 85.8 yr and P4 = 42.5 yr and semi-amplitudes of K3 = 0.013 days and K4 = 0.007 days, respectively. The most reasonable explanation for them is a pair of light-time-travel (LTT) effects driven by the existence of two M-type companions with minimum masses of M3 = 0.22 M? and M4 = 0.19 M?, located at nearly 2:1 mean motion resonance. Then, SZ Her is a quadruple system and the 3rd and 4th components would stay in the stable orbital resonance.

Lee, J. W.; Lee, C.-U.; Kim, S.-L.; Kim, H.-I.; Park, J.-H.; Hinse, T. C.

2012-04-01

77

Effect of Guard Period Insertion in MIMO OFDM System  

Directory of Open Access Journals (Sweden)

Full Text Available Orthogonal frequency-division multiplexing (OFDM) is the technique of choice in the digital broad-band applications, which divides a channel with a higher relative data rate into several orthogonal sub-channels with a lower data rate. This very special feature of OFDM technique attracts the new generation of communication, which in mobile communication terminology called as “4th generation technology”. This paper is an approach towards very important aspect/ performance parameter of OFDM. First we will talk about the key role of Guard Period insertion in OFDM system in optimize Inter-Symbol Interference (ISI). Secondly, how the different method/way of adding guard period effect the OFDM system performance is also discussed & elaborated with help of MATLAB simulated results.

Mitalee Agrawal,; Yudhishthir Raut

2011-01-01

78

Dielectric Response of Periodic Systems from Quantum Monte Carlo Calculations  

CERN Multimedia

We present a novel approach that allows to calculate the dielectric response of periodic systems in the quantum Monte Carlo formalism. We employ a many-body generalization for the electric enthalpy functional, where the coupling with the field is expressed via the Berry-phase formulation for the macroscopic polarization. A self-consistent local Hamiltonian then determines the ground-state wavefunction, allowing for accurate diffusion quantum Monte Carlo calculations where the polarization's fixed point is estimated from the average on an iterative sequence, sampled via forward-walking. This approach has been validated for the case of an isolated hydrogen atom, and then applied to a periodic system, to calculate the dielectric susceptibility of molecular-hydrogen chains. The results found are in excellent agreement with the best estimates obtained from the extrapolation of quantum-chemistry calculations.

Umari, P; Galli, G; Marzari, N; Galli, Giulia; Marzari, Nicola

2005-01-01

79

Fractal spectrum of a quasi-periodically driven spin system  

CERN Multimedia

We numerically perform a spectral analysis of a quasi-periodically driven spin 1/2 system, the spectrum of which is Singular Continuous. We compute fractal dimensions of spectral measures and discuss their connections with the time behaviour of various dynamical quantities, such as the moments of the distribution of the wave packet. Our data suggest a close similarity between the information dimension of the spectrum and the exponent ruling the algebraic growth of the 'entropic width' of wavepackets.

Guarneri, I; Guarneri, I; DiMeo, M

1995-01-01

80

Stability Analysis for Multi-Parameter Linear Periodic Systems  

DEFF Research Database (Denmark)

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.

Seyranian, A.P.; Solem, Frederik

1999-01-01

 
 
 
 
81

Averaging of time-periodic systems without a small parameter  

CERN Multimedia

In this article, we present a new approach to averaging in non-Hamiltonian systems with periodic forcing. The results here do not depend on the existence of a small parameter. In fact, we show that our averaging method fits into an appropriate nonlinear equivalence problem, and that this problem can be solved formally by using the Lie transform framework to linearize it. According to this approach, we derive formal coordinate transformations associated with both first-order and higher-order averaging, which result in more manageable formulae than the classical ones. Using these transformations, it is possible to correct the solution of an averaged system by recovering the oscillatory components of the original non-averaged system. In this framework, the inverse transformations are also defined explicitly by formal series; they allow the estimation of appropriate initial data for each higher-order averaged system, respecting the equivalence relation. Finally, we show how these methods can be used for identifyi...

Chekroun, Mickaël D; Roux, Jean; Varadi, Ferenc

2010-01-01

82

Geological and geochemical criteria for the continental nature of the Mendeleev Rise (the Arctic Ocean) from the data of drilling and dredging of seabed rock material  

Science.gov (United States)

The results are presented of geological and geophysical studies on the Mendeleev Rise at 10 test sites at 79°N to 83°N (expedition "Arktika-2012" in August-September 2012). During the expedition, for the first time, three boreholes were drilled in the bedrocks of the Mendeleev Rise basement at a depth of 1700-2600 m, and more than 20 thousand fragments of seabed rock material were dredged. Among them carbonate-bearing rocks including dolomite with relicts of trilobites and ostracoderms (D3-C) constitute up 65 %. Up to 20% are terrigenous rocks with a predominance of quartz sandstones. Magmatic rocks constitute 10-15% of the samples (including 8% of gabbro-dolerite and 2 % of granite) with 5% of metamorphic rocks. The boreholes revealed magmatic mafic rocks of basalt to basaltic andesite to trachyandesite series (SiO2-48-58% K2O+Na2O-3,4-9,2%) including epigenically altered volcanic breccias. All fragments of magmatic mafic rocks have a similar mineral and chemical composition and are grouped with gabbro dolerite (SiO2-49-51%, K2O+Na2O-2,5-3,0%). Preliminary results of mineralogic, geochemical and of isotopic geochemical (ICP-OEC, ICP-MS, RFA, Sm-Nd, Rb-Sr, EPMA and others) analyses suggest the continental nature of the studied rocks and show a distinct difference from rocks of the Gakkel Ridge in the Eurasian part of the ocean, which are of the oceanic origin. U-Pb dating of zircons from the core rocks and seabed rock material (SIMS SHRIMP II) indicate a wide range of their formation age: 2940-995, 639-385 and 303-203 Ma and thus suggest that they belong to volcanogenic terrigeneous carbonate-bearing bed of the ancient platform composing the floor of Amerasian part of the Arctic Ocean.

Morozov, Andrey; Petrov, Oleg; Kremenetskiy, Alexander; Kashubin, Sergey; Rekant, Pavel; Gusev, Eugene; Shokalskiy, Sergey; Shevchenko, Sergey; Sergeev, Sergey; Artyushkov, Eugene

2013-04-01

83

Dimension Reduction Near Periodic Orbits of Hybrid Systems  

CERN Multimedia

When the Poincar\\'{e} map associated with a periodic orbit of a hybrid dynamical system has constant-rank iterates, we demonstrate the existence of a constant-dimensional invariant subsystem near the orbit which attracts all nearby trajectories in finite time. This result shows that the long-term behavior of a hybrid model with a large number of degrees-of-freedom may be governed by a low-dimensional smooth dynamical system. The appearance of such simplified models enables the translation of analytical tools from smooth systems-such as Floquet theory-to the hybrid setting and provides a bridge between the efforts of biologists and engineers studying legged locomotion.

Burden, Samuel; Sastry, S Shankar

2011-01-01

84

ECONOMIC AND FINANCIAL PERIODS INDUCED THROUGH BANKING SYSTEM  

Directory of Open Access Journals (Sweden)

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.

Ionita Rodica -Oana

2013-01-01

85

Periodic solutions of second order Hamiltonian systems bifurcating from infinity  

CERN Multimedia

The goal of this article is to study closed connected sets of periodic solutions, of autonomous second order Hamiltonian systems, emanating from infinity. The main idea is to apply the degree for SO(2)-equivariant gradient operators defined by the second author. Using the results due to Rabier we show that we cannot apply the Leray-Schauder degree to prove the main results of this article. It is worth pointing out that since we study connected sets of solutions, we also cannot use the Conley index technique and the Morse theory.

Rybicki, J F S

2006-01-01

86

Stability analysis of periodically switched linear systems using Floquet theory  

Directory of Open Access Journals (Sweden)

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.

Gökçek Cevat

2004-01-01

87

Combinatorial Bethe Ansatz and Generalized Periodic Box-Ball System  

Science.gov (United States)

We reformulate the Kerov-Kirillov-Reshetikhin (KKR) map in the combinatorial Bethe ansatz from paths to rigged configurations by introducing local energy distribution in crystal base theory. Combined with an earlier result on the inverse map, it completes the crystal interpretation of the KKR bijection for Uq(widehat { {sl}}2). As an application, we solve an integrable cellular automaton, a higher spin generalization of the periodic box-ball system, by an inverse scattering method and obtain the solution of the initial value problem in terms of the ultradiscrete Riemann theta function.

Kuniba, Atsuo; Sakamoto, Reiho

88

Existence, Uniqueness and Asymptotic Stability of Time Periodic Traveling Waves for a Periodic Lotka-Volterra Competition System with Diffusion.  

Science.gov (United States)

We study the existence, uniqueness, and asymptotic stability of time periodic traveling wave solutions to a periodic diffusive Lotka-Volterra competition system. Under certain conditions, we prove that there exists a maximal wave speed c(*) such that for each wave speed c ? c(*), there is a time periodic traveling wave connecting two semi-trivial periodic solutions of the corresponding kinetic system. It is shown that such a traveling wave is unique modulo translation and is monotone with respect to its co-moving frame coordinate. We also show that the traveling wave solutions with wave speed c c(*). PMID:21572575

Zhao, Guangyu; Ruan, Shigui

2011-06-01

89

Robust detection of periodic time series measured from biological systems  

Directory of Open Access Journals (Sweden)

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/.

Ahdesmäki Miika; Lähdesmäki Harri; Pearson Ron; Huttunen Heikki; Yli-Harja Olli

2005-01-01

90

Z Cha in superoutburst: periodic variation in the systemic velocity  

International Nuclear Information System (INIS)

Photometric and spectroscopic data from the May 1984 and December 1985 superoutbursts of the SU UMa system Z Cha are presented. By fitting composite absorption and emission profiles to the spectroscopic data, radial velocity curves were produced for each night using H?, H?, H?, He I?4471, and Ca II K. The mean (?) of each of these velocity curves is found to be non-zero (i.e. they do not represent the quiescent value of the systemic velocity) and it is found that ? is modulated on the superhump beat period of 2.1 days with a zero-velocity phase of ? 0.75, and amplitude of ? 80 km s-1. The mean of the modulation is compatible with the quiescent value of ? = 0 ± 9 km s-1. This observational result is interpreted with new non-axisymmetric disc simulations as arising in an eccentric, precessing disc which is tidally distorted by the secondary. (author).

1988-01-01

91

Wide aperture periodic lens system for multiple Compton backscattering  

International Nuclear Information System (INIS)

Polarized ?-ray generation by Compton backscattering in a periodic focusing system of electron and laser beams is discussed for the production of polarized positron beam in a linear collider. Circularly polarized CO2 laser beams are focused by an optical lens series and collided with a 5.8 GeV electron beam to generate circularly polarized ?-rays with 60 MeV at a maximum. In the present work, the basic concept of periodic lens system discussed previously is reconsidered to reduce the laser power required for a ?-ray yield of 7x1015 ?/s and the peak laser power density at lenses as much as possible for technical practice. The electron beam is focused by a series of permanent quadrupole magnets with a FODO structure. The power is reduced to six sources with 5.6 kW each, and the peak power density is reduced to 1.4 GW/cm2. These values can be reduced further by using a longer laser pulse length and a damping ring for the electron beam.

2002-10-01

92

Wide aperture periodic lens system for multiple Compton backscattering  

CERN Multimedia

Polarized gamma-ray generation by Compton backscattering in a periodic focusing system of electron and laser beams is discussed for the production of polarized positron beam in a linear collider. Circularly polarized CO sub 2 laser beams are focused by an optical lens series and collided with a 5.8 GeV electron beam to generate circularly polarized gamma-rays with 60 MeV at a maximum. In the present work, the basic concept of periodic lens system discussed previously is reconsidered to reduce the laser power required for a gamma-ray yield of 7x10 sup 1 sup 5 gamma/s and the peak laser power density at lenses as much as possible for technical practice. The electron beam is focused by a series of permanent quadrupole magnets with a FODO structure. The power is reduced to six sources with 5.6 kW each, and the peak power density is reduced to 1.4 GW/cm sup 2. These values can be reduced further by using a longer laser pulse length and a damping ring for the electron beam.

Miyahara, Y

2002-01-01

93

Singular Continuous Floquet Operator for Periodic Quantum Systems  

CERN Document Server

Consider the Floquet operator of a time independent quantum system, acting on a separable Hilbert space, periodically perturbed by a rank one kick: $e^{-iH_0T}e^{-i\\kappa T |\\phi\\ket\\bra\\phi|}$ where $T$, $\\kappa$ are respectively the period and the coupling constant and $H_0$ is a pure point self-adjoint operator, bounded from below. Under some hypotheses on the vector $\\phi$, cyclic for $H_0$ we prove the following: If the gaps between the eigenvalues $(\\lambda_n)$ are such that: $\\lambda_{n+1}-\\lambda_{n}\\geq C n^{-\\gamma}$ for some $\\gamma \\in ]0,1[$ and $C>0$, then the Floquet operator of the perturbed system is purely singular continuous T-a.e. If $H_0$ is the Hamiltonian of the one-dimensional rotator on $L^2({\\mathbb R}/T_0{\\mathbb Z})$ and the ratio $2\\pi T/T_0^2$ is irrational, then the Floquet operator is purely singular continuous as soon as $\\kappa T \

Bourget, O

2004-01-01

94

On linear stability of steady space-periodic magnetohydrodynamic systems to perturbations involving large periods  

CERN Multimedia

I construct a complete asymptotic expansion of solutions to the problem of linear stability of three-dimensional steady space-periodic magnetohydrodynamic states to perturbations involving large periods. Eddy diffusivity tensor is derived for parity-invariant steady states. I present numerical evidences that if perturbations of the flow are permitted, then the effect of negative eddy diffusivity emerges at much larger magnetic molecular diffusivities than in the kinematic dynamo problem (where no perturbations of the flow are assumed).

Zheligovsky, V A

2005-01-01

95

Development of a Periodic Loading System using a Bellows  

International Nuclear Information System (INIS)

An instrumented capsule is one of the devices to investigate the irradiation effects of the nuclear reactor materials and components being used in a research reactor, HANARO. Among various capsules, a special capsule for in-pile creep and fatigue tests has been under development since 2002. A bellows was used to apply the constant load to the specimen in the creep capsule, and various studies have been performed to determine the specification of the bellows. But the load's concept for the fatigue test is slightly different with the creep test. It is necessary to repeat a force with a constant period and amplitude during the life of the specimen. Thus, for the fatigue test using an instrumented capsule, it is important to realize the load's shape being applied to the specimen. In this study, the out-pile loading system using the bellows to apply the actual fatigue capsule is developed, and it is performed by modifying the previous system which was developed for the out-pile creep test. The basic structure, the control system and the main function related to the new loading system are described, and the preliminary test results and the future works are also discussed

2005-01-01

96

Period and period change measurements for 143 SuperWASP eclipsing binary candidates near the short-period limit and discovery of a doubly eclipsing quadruple system  

Science.gov (United States)

Building on previous work, a new search of the SuperWASP archive was carried out to identify eclipsing binary systems near the short-period limit. 143 candidate objects were detected with orbital periods between 16 000 and 20 000 s, of which 97 are new discoveries. Period changes significant at 1? or more were detected in 74 of these objects, and in 38 the changes were significant at 3? or more. The significant period changes observed followed an approximately normal distribution with a half-width at half-maximum of ~0.1 s yr-1. There was no apparent relationship between period length and magnitude or direction of period change. Amongst several interesting individual objects studied, 1SWASP J093010.78+533859.5 is presented as a new doubly eclipsing quadruple system, consisting of a contact binary with a 19 674.575 s period and an Algol-type binary with a 112 799.109 s period, separated by 66.1 AU, being the sixth known system of this type. Table 1 and Fig. 12 are available in electronic form at http://www.aanda.org

Lohr, M. E.; Norton, A. J.; Kolb, U. C.; Maxted, P. F. L.; Todd, I.; West, R. G.

2013-01-01

97

Geometry optimization of periodic systems using internal coordinates.  

UK PubMed Central (United Kingdom)

An algorithm is proposed for the structural optimization of periodic systems in internal (chemical) coordinates. Internal coordinates may include in addition to the usual bond lengths, bond angles, out-of-plane and dihedral angles, various "lattice internal coordinates" such as cell edge lengths, cell angles, cell volume, etc. The coordinate transformations between Cartesian (or fractional) and internal coordinates are performed by a generalized Wilson B-matrix, which in contrast to the previous formulation by Kudin et al. [J. Chem. Phys. 114, 2919 (2001)] includes the explicit dependence of the lattice parameters on the positions of all unit cell atoms. The performance of the method, including constrained optimizations, is demonstrated on several examples, such as layered and microporous materials (gibbsite and chabazite) as well as the urea molecular crystal. The calculations used energies and forces from the ab initio density functional theory plane wave method in the projector-augmented wave formalism.

Bucko T; Hafner J; Angyán JG

2005-03-01

98

Geometry optimization of periodic systems using internal coordinates  

Science.gov (United States)

An algorithm is proposed for the structural optimization of periodic systems in internal (chemical) coordinates. Internal coordinates may include in addition to the usual bond lengths, bond angles, out-of-plane and dihedral angles, various ``lattice internal coordinates'' such as cell edge lengths, cell angles, cell volume, etc. The coordinate transformations between Cartesian (or fractional) and internal coordinates are performed by a generalized Wilson B-matrix, which in contrast to the previous formulation by Kudin et al. [J. Chem. Phys. 114, 2919 (2001)] includes the explicit dependence of the lattice parameters on the positions of all unit cell atoms. The performance of the method, including constrained optimizations, is demonstrated on several examples, such as layered and microporous materials (gibbsite and chabazite) as well as the urea molecular crystal. The calculations used energies and forces from the ab initio density functional theory plane wave method in the projector-augmented wave formalism.

Bu?ko, Tomáš; Hafner, Jürgen; Ángyán, János G.

2005-03-01

99

Spectral theory of time-periodic many-body systems  

CERN Multimedia

We study the spectrum of the monodromy operator for an N-body quantum system in a time-periodic external field with time-mean equal to zero. This includes AC-Stark and circularly polarized fields, and pair-potentials with a local singularity up to (and including) the Coulomb singularity. In the framework of Floquet theory we prove a local commutator estimate and use it to prove a Limiting Absorption Principle for the Floquet Hamiltonian as well as exponential decay estimates on non-threshold eigenfunctions. These two results are then used to obtain a second order perturbation theory for embedded eigenvalues. The principal tool is a new extended Mourre theory.

Schach-Moeller, J

2002-01-01

100

Existence, Uniqueness and Asymptotic Stability of Time Periodic Traveling Waves for a Periodic Lotka-Volterra Competition System with Diffusion.  

UK PubMed Central (United Kingdom)

We study the existence, uniqueness, and asymptotic stability of time periodic traveling wave solutions to a periodic diffusive Lotka-Volterra competition system. Under certain conditions, we prove that there exists a maximal wave speed c(*) such that for each wave speed c ? c(*), there is a time periodic traveling wave connecting two semi-trivial periodic solutions of the corresponding kinetic system. It is shown that such a traveling wave is unique modulo translation and is monotone with respect to its co-moving frame coordinate. We also show that the traveling wave solutions with wave speed c < c(*) are asymptotically stable in certain sense. In addition, we establish the nonexistence of time periodic traveling waves for nonzero speed c > c(*).

Zhao G; Ruan S

2011-06-01

 
 
 
 
101

The Higgs Boson in the Periodic System of Elementary Particles  

Directory of Open Access Journals (Sweden)

Full Text Available It is proposed that the observed Higgs Boson at the LHC is the Standard Model Higgs boson that adopts the existence of the hidden lepton condensate. The hidden lepton is in the forbidden lepton family, outside of the three lepton families of the Standard Model. Being forbidden, a single hidden lepton cannot exist alone; so it must exist in the lepton condensate as a composite of ?’ and ?’± hidden leptons and their corresponding antileptons. The calculated average mass of the hidden lepton condensate is 128.8 GeV in good agreements with the observed 125 or 126 GeV. The masses of the hidden lepton condensate and all elementary particles including leptons, quarks, and gauge bosons are derived from the periodic system of elementary particles. The calculated constituent masses are in good agreement with the observed values by using only four known constants: the number of the extra spatial dimensions in the eleven-dimensional membrane, the mass of electron, the mass of Z boson, and the fine structure constant.

Ding-Yu Chung; Ray Hefferlin

2013-01-01

102

Stability of periodic solutions of index-2 differential algebraic systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper deals with periodic index-2 differential algebraic equations and the question whether a periodic solution is stable in the sense of Lyapunov. As the main result, a stability criterion is proved.This criterion is formulated in terms of the original data so that it may be used in practi...

Lamour, René; März, Roswitha; Winkler, Renate

103

Relation between non uniform magnetic field and close binary systems period  

Directory of Open Access Journals (Sweden)

Full Text Available  Magnetic activity of one or both components of close binary systems can cause orbital period variation of the systems.Variation in gravitational quadropole moment will change the orbital period of the systems. In this article, we suppose that magnetic field is poloidal-troidal according to dynamo theory, and finds its relation with period change in the systems.

M Zahedi; D Jassur

2011-01-01

104

ORBITAL SYSTEM OF DISTRIBUTION OF ELECTRONS IN ATOM AND STRUCTURE OF PERIODIC SYSTEM OF ELEMENTS ??????????? ??????? ????????????? ?????????? ? ????? ? ????????? ????????????? ??????? ?????????  

Directory of Open Access Journals (Sweden)

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

Vyatkin V. B.

2013-01-01

105

Periodic Orbits in a Simple Ray-Splitting System  

CERN Multimedia

We study ray dynamics in a square billiard that allows mode conversion and is parametrised by $\\kappa$, the ratio of the velocities of the two modes. At orbits proliferate exponentially. As $\\kappa$ increases beyond $\\sqrt{2}$, the collection of daughter rays explore only three momentum directions and mode conversion is progressively inhibited. We provide an algorithm for determining periodic orbits when $\\kappa > \\sqrt{2}$ and show numerically that exponential proliferation persists around $\\kappa \\simeq \\sqrt{2}$ but as $\\kappa$ increases, a crossover to sub-exponential behaviour occurs for short periods. We discuss these results in the light of conservation laws.

Biswas, D

1996-01-01

106

Fixed Point Indices and Invariant Periodic Sets of Holomorphic Systems  

CERN Multimedia

This note presents a method to study center families of periodic orbits of complex holomorphic differential equations near singularities, based on some iteration properties of fixed point indices. As an application of this method, we will prove Needham's theorem in a more general version.

Zhang, G Y

2005-01-01

107

Branching of periodic orbits in reversible hamiltonian systems  

CERN Multimedia

This paper deals with the dynamics of time-reversible Hamiltonian vector fields with 2 and 3 degrees of freedom around an elliptic equilibrium point in presence of symplectic involutions. The main results discuss the existence of one-parameter families of reversible periodic solutions terminating at the equilibrium. The main techniques used are Birkhoff and Belitskii normal forms combined with the Liapunov-Schmidt reduction.

Buzzi, Claudio; Teixeira, Marco Antonio

2010-01-01

108

Chaos in periodically forced Holling type IV predator-prey system with impulsive perturbations  

Energy Technology Data Exchange (ETDEWEB)

The effect of periodic forcing and impulsive perturbations on predator-prey model with Holling type IV functional response is investigated. The periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of the prey. The impulsive perturbations are affected by introducing periodic constant impulsive immigration of predator. The dynamical behavior of the system is simulated and bifurcation diagrams are obtained for different parameters. The results show that periodic forcing and impulsive perturbation can easily give rise to complex dynamics, including (1) quasi-periodic oscillating, (2) period doubling cascade, (3) chaos, (4) period halfing cascade.

Zhang Shuwen [Institute of Biomathematics, Anshan Normal University, Liaoning, Anshan 114005 (China)] e-mail: anzsw_123@163.com; Tan Dejun [Institute of Biomathematics, Anshan Normal University, Liaoning, Anshan 114005 (China)] e-mail: tdj650314@163.com; Chen Lansun [Department of Applied Mathematics, Dalian University of Technology, Liaoning, Dalian 116024 (China)] e-mail: lschen@math08.math.ac.cn

2006-02-01

109

Chaos in periodically forced Holling type IV predator-prey system with impulsive perturbations  

International Nuclear Information System (INIS)

The effect of periodic forcing and impulsive perturbations on predator-prey model with Holling type IV functional response is investigated. The periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of the prey. The impulsive perturbations are affected by introducing periodic constant impulsive immigration of predator. The dynamical behavior of the system is simulated and bifurcation diagrams are obtained for different parameters. The results show that periodic forcing and impulsive perturbation can easily give rise to complex dynamics, including (1) quasi-periodic oscillating, (2) period doubling cascade, (3) chaos, (4) period halfing cascade.

2006-01-01

110

Chaos in periodically forced Holling type II predator-prey system with impulsive perturbations  

Energy Technology Data Exchange (ETDEWEB)

The effect of periodic forcing and impulsive perturbations on predator-prey model with Holling type II functional response is investigated. The periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of prey. The impulsive perturbation is affected by introducing periodic constant impulsive immigration of predator. The dynamical behavior of the system is simulated and bifurcation diagrams are obtained for different parameters. The results show that periodic forcing and impulsive perturbation can very easily give rise to complex dynamics, including (1) quasi-periodic oscillating, (2) period doubling cascade, (3) chaos, (4) period halfing cascade, (5) non-unique dynamics.

Zhang Shuwen [Institute of Biomathematics, Anshan Normal University, Liaoning, Anshan 114005 (China)] e-mail: anzsw_123@163.com; Tan Dejun [Institute of Biomathematics, Anshan Normal University, Liaoning, Anshan 114005 (China)] e-mail: tdj650314@163.com; Chen Lansun [Department of Applied Mathematics, Dalian University of Technology, Liaoning, Dalian 116024 (China)] e-mail: lschen@math08.math.ac.cn

2006-04-01

111

Chaos in periodically forced Holling type II predator-prey system with impulsive perturbations  

International Nuclear Information System (INIS)

The effect of periodic forcing and impulsive perturbations on predator-prey model with Holling type II functional response is investigated. The periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of prey. The impulsive perturbation is affected by introducing periodic constant impulsive immigration of predator. The dynamical behavior of the system is simulated and bifurcation diagrams are obtained for different parameters. The results show that periodic forcing and impulsive perturbation can very easily give rise to complex dynamics, including (1) quasi-periodic oscillating, (2) period doubling cascade, (3) chaos, (4) period halfing cascade, (5) non-unique dynamics.

2006-01-01

112

Periodic solutions of systems with asymptotically even nonlinearities  

Directory of Open Access Journals (Sweden)

Full Text Available New conditions of solvability based on a general theorem on the calculation of the index at infinity for vector fields that have degenerate principal linear part as well as degenerate ?next order? terms are obtained for the 2?-periodic problem for the scalar equation x?+n2x=g(|x|)+f(t,x)+b(t) with bounded g(u) and f(t,x)?0 as |x|?0. The result is also applied to the solvability of a two-point boundary value problem and to resonant problems for equations arising in control theory.

Peter E. Kloeden; Alexander M. Krasnosel'skii

2000-01-01

113

Permanence and Stable Periodic Solution for a Discrete Competitive System with Multidelays  

Directory of Open Access Journals (Sweden)

Full Text Available The permanence and the existence of periodic solution for a discrete nonautonomous competitive system with multidelays are considered. Also the stability of the periodic solution is discussed. Numerical examples are given to confirm the theoretical results.

Chunqing Wu

2009-01-01

114

A nonlinear system under combined periodic and random excitation  

Energy Technology Data Exchange (ETDEWEB)

The anharmonic oscillator under combined sinusoidal and white noise excitation is studied using the Gaussian closure approximation. The mean response and the steady-state variance of the system is obtained by the WKBJ approximation and also by the Fokker-Planck equation. The multiple steady-state solutions are obtained and their stability analysis is presented. Numeric al results are obtained for a particular set of system parameters. The theoretical results are compared with a digital simulation study to bring out the usefulness of the present approximate theory.

Iyengar, R.N.

1986-09-01

115

Hybrid control of period-doubling bifurcation and chaos in discrete nonlinear dynamical systems  

Energy Technology Data Exchange (ETDEWEB)

It is a typical route to generate chaos via period-doubling bifurcations in some nonlinear systems. In this paper, we propose a new hybrid control strategy in which state feedback and parameter perturbation are used to control the period-doubling bifurcations and to stabilize unstable periodic orbits embedded in the chaotic attractor of a discrete chaotic dynamical system. Simulation shows that the higher stable 2{sup n}-periodic orbit of the system can be controlled to lower stable 2{sup m}-periodic orbits (m

Luo Xiaoshu E-mail: xsluo@mail.ustc.edu.cn; Chen Guanrong; Bing, H.-W.; Jin, Q.-F

2003-11-01

116

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.)

1992-01-01

117

Periodic inspection for safety of CANDU heat transport piping systems  

International Nuclear Information System (INIS)

An approach has been developed for the prediction of the risk of failure or the survival of heat transport piping systems in a nuclear power plant. The effects of various inspection schemes on the risk of failure have been investigated and an inspection method proposed. A list of input data required to apply this method to real situations is specified. Using an example of a pressurized pipe containing a defect, it is shown that the required data can be obtained easily.

1981-01-01

118

Statistical mechanics of time-periodic quantum systems Statistische Mechanik zeitperiodischer Quantensysteme  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 str...

Waltraut Wustmann

119

Spectral singularities in PT-symmetric periodic finite-gap systems  

CERN Document Server

The origin of spectral singularities in finite-gap singly periodic PT-symmetric quantum systems is investigated. We show that they emerge from a limit of band-edge states in a doubly periodic finite gap system when the imaginary period tends to infinity. In this limit, the energy gaps are contracted and disappear, every pair of band states of the same periodicity at the edges of a gap coalesces and transforms into a singlet state in the continuum. As a result, these spectral singularities turn out to be analogous to those in the non-periodic systems, where they appear as zero-width resonances. The specific degeneration related to the presence of finite number of spectral singularities in periodic quantum systems with compact and non-compact topologies is shown to be coherently reflected by a hidden, bosonized nonlinear supersymmetry.

Correa, Francisco

2012-01-01

120

Controlling chaos in a high dimensional system with periodic parametric perturbations  

Energy Technology Data Exchange (ETDEWEB)

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.

Mirus, K.A.; Sprott, J.C.

1998-10-01

 
 
 
 
121

Positive periodic solutions for an impulsive ratio-dependent predator-prey system with delays  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, we study a periodic ratio-dependent predator-prey system of two species with impulse and multiple time delays. By means of analysis techniques and the continuation theorem of coincidence degree theory, we obtain sufficient conditions for the existence of positive periodic solutions of the system. Our results extend previous results obtained in [9].

Yan Liu; Quanyi Wang

2008-01-01

122

Tropical Krichever construction for the non-periodic box and ball system  

International Nuclear Information System (INIS)

A solution for an initial value problem of the box and ball system is constructed from a solution of the periodic box and ball system. The construction is done through a specific limiting process based on the theory of tropical geometry. This method gives a tropical analogue of the Krichever construction, which is an algebro-geometric method to construct exact solutions to integrable systems, for the non-periodic system. (paper)

2012-10-05

123

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.

1998-01-01

124

Stabilization of Periodic Solutions in a Thedered Satellite System by Damping Injection  

DEFF Research Database (Denmark)

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.

Larsen, Martin Birkelund; Blanke, Mogens

2009-01-01

125

Stability and robustness analysis of a linear time-periodic system subjected to random perturbations  

Science.gov (United States)

In this work, new methods of guaranteeing the stability of linear time periodic dynamical systems with stochastic perturbations are presented. In the approaches presented here, the Lyapunov-Floquet (L-F) transformation is applied first so that the linear time-periodic part of the equations becomes time-invariant. For the linear time periodic system with stochastic perturbations, a stability theorem and related corollary have been suggested using the results previously obtained by Infante. This technique is not only applicable to systems with stochastic parameters but also to systems with deterministic variation in parameters. Some illustrative examples are presented to show the practical applications. These methods can be used to investigate the degree of robustness and design controllers for systems with time periodic coefficients subjected to random perturbations.

Redkar, Sangram; Liu, J.; Sinha, S. C.

2012-03-01

126

Mean switching frequency locking in stochastic bistable systems driven by periodical force  

CERN Document Server

The nonlinear response of noisy bistable systems driven by strong amplitude periodical force is investigated by physical experiment. The new phenomenon of locking of the mean switching frequency between states of bistable system is found. It is shown that there is an interval of noise intensities in which the mean switching frequency remains constant and coincides with the frequency of external periodic force. The region on the parameter plane ``noise intensity - amplitude of periodic excitation'' which corresponds to this phenomenon is similar to the synchronization (phase-locking) region (Arnold's tongue) in classical oscillatory systems.

Shulgin, B; Anishchenko, V S; Shulgin, Boris; Neiman, Alexander; Anishchenko, Vadim

1995-01-01

127

The Periodic Solutions of the Compound Singular Fractional Differential System with Delay  

Directory of Open Access Journals (Sweden)

Full Text Available The paper gives sufficient conditions on the existence of periodic solution for a class of compound singular fractional differential systems with delay, involving Nishimoto fractional derivative. Furthermore, for the particular functions, the necessary conditions on the existence of periodic solution are also derived. Especially, for two-dimensional compound singular fractional differential equation with delay, the criteria of existence of periodic solution are obtained. Finally, two examples are presented to verify the validity of criteria.

XuTing Wei; XuanZhu Lu

2010-01-01

128

Stochastic long term modelling of a drainage system with estimation of return period uncertainty.  

UK PubMed Central (United Kingdom)

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 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.

Thorndahl S

2009-01-01

129

Stochastic long term modelling of a drainage system with estimation of return period uncertainty.  

Science.gov (United States)

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 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. PMID:19542638

Thorndahl, S

2009-01-01

130

Stochastic Long Term Modelling of a Drainage System with Estimation of Return Period Uncertainty  

DEFF Research Database (Denmark)

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.

Thorndahl, SØren

2008-01-01

131

Stochastic long term modelling of a drainage system with estimation of return period uncertainty  

DEFF Research Database (Denmark)

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.

Thorndahl, SØren

2009-01-01

132

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.

2007-01-01

133

The Bethe ansatz in a periodic box ball system and the ultradiscrete Riemann theta function  

Science.gov (United States)

Vertex models with quantum group symmetry give rise to integrable cellular automata at q = 0. We study a prototype example known as the periodic box-ball system. The initial value problem is solved in terms of an ultradiscrete analogue of the Riemann theta function whose period matrix originates in the Bethe ansatz at q = 0.

Kuniba, Atsuo; Sakamoto, Reiho

2006-09-01

134

Positive almost periodic solutions of non-autonomous delay competitive systems with weak Allee effect  

Directory of Open Access Journals (Sweden)

Full Text Available By using Mawhin's continuation theorem of coincidence degree theory, we obtain sufficient conditions for the existence of positive almost periodic solutions for a non-autonomous delay competitive system with weak Allee effect.

Yongkun Li; Kaihong Zhao

2009-01-01

135

Differences in cardiovascular and central nervous system responses to periods of mental work with a break.  

UK PubMed Central (United Kingdom)

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.

Liu X; Iwakiri K; Sotoyama M; Iwanaga K

2013-08-01

136

Dynamical system for learning the waveform and frequency of periodic signals - application to drumming  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper presents a two-layered system for learning and encoding a periodic signal and its application to a drumming task. The two layers are the dynamical system responsible for extracting the main frequency of the input signal, based on adaptive frequency oscillators, and the dynamical system res...

Gams, Andrej; Degallier, Sarah; Ijspeert, Auke; Lenarcic, Jadran

137

Control of nonlinear systems using periodic parametric perturbations with application to a reversed field pinch  

Energy Technology Data Exchange (ETDEWEB)

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.

Mirus, K.A.

1998-06-01

138

Bethe ansatz and inverse scattering transform in a periodic box-ball system  

CERN Document Server

We formulate the inverse scattering method for a periodic box-ball system and solve the initial value problem. It is done by a synthesis of the combinatorial Bethe ansa"tze at q=1 and q=0, which provides the ultradiscrete analogue of quasi-periodic solutions in soliton equations, e.g., action-angle variables, Jacobi varieties, period matrices and so forth. As an application we establish explicit formulas counting the states characterized by conserved quantities and the generic and fundamental period under the commuting family of time evolutions.

Kuniba, A; Takenouchi, A; Kuniba, Atsuo; Takagi, Taichiro; Takenouchi, Akira

2006-01-01

139

A Possible Correlation between Mass Ratio and Period Ratio in Multiple Planetary Systems  

CERN Document Server

We report on a possible correlation between the mass ratio and period ratio of pairs of adjacent planets in extra-solar planetary systems. Monte-Carlo simulations show that the effect is significant to level of 0.7%, as long as we exclude two pairs of planets whose periods are at the 1:2 resonance. Only the next few multiple systems can tell if the correlation is real.

Mazeh, T; Mazeh, Tsevi; Zucker, Shay

2003-01-01

140

A Unified Floquet Theory for Discrete, Continuous, and Hybrid Periodic Linear Systems  

CERN Multimedia

In this paper, we study periodic linear systems on periodic time scales which include not only discrete and continuous dynamical systems but also systems with a mixture of discrete and continuous parts (e.g. hybrid dynamical systems). We develop a comprehensive Floquet theory including Lyapunov transformations and their various stability preserving properties, a unified Floquet theorem which establishes a canonical Floquet decomposition on time scales in terms of the generalized exponential function, and use these results to study homogeneous as well as nonhomogeneous periodic problems. Furthermore, we explore the connection between Floquet multipliers and Floquet exponents via monodromy operators in this general setting and establish a spectral mapping theorem on time scales. Finally, we show this unified Floquet theory has the desirable property that stability characteristics of the original system can be determined via placement of an associated (but time varying) system's poles in the complex plane. We in...

DaCunha, Jeffrey J

2009-01-01

 
 
 
 
141

Stability of linear particle motion in arbitrary periodic focusing and accelerating systems  

Energy Technology Data Exchange (ETDEWEB)

Stability of transverse and longitudinal particle motion in arbitrary periodic system is studied. Actions of the focusing and phasing forces are approximated by linear thin lenses. On the basis of smooth approach to a solution of motion equations general formulas for the Floquet functions in focusing and accelerating systems are derived. The formulas are accurate for a period containing two thin lenses. If a period contains more lenses the formulas remain approximately valid over a wide parameter range. The proposed approach enables to study directly a dependence of specific values of the Floquet functions on a period structure. It significantly simplifies a search of an optimum period configuration satisfying the given requirements. Application of the formulas to calculate the particle motion stability in the RF crossed lens focused linac is considered.

Balabin, A.I.; Kropachev, G.N. E-mail: kropachev@vitep5.itep.ru; Ugarov, S.B

1999-05-01

142

Relative equailibria and relative periodic solutions in systems with time-delay and $S^{1}$ symmetry  

CERN Multimedia

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.

Yanchuk, Serhiy

2013-01-01

143

Speaking period detection device, voice recognition processing device, transmission system, signal level control device and speaking period detection method  

UK PubMed Central (United Kingdom)

A speaking period required for a voice recognition processing is detected with a simple and robust approach. A speaking period is detected based on an EMG generated when a speaker speaks. A large amplitude is observed in an EMG as muscular activity is caused when a speaker speaks. By observing this, a speaking period can be detected. The EMG can be measured from the speaker's skin via electrodes provided on a mobile-type terminal. Since a mobile-type terminal is usually pressed to the skin for use, affinity between this use form and the present invention is very high.

MANABE HIROYUKI; HIRAIWA AKIRA; HIRAIWA LEGAL REPRESENTATIVE YUMIKO; HAYASHI KOUKI; SUGIMURA TOSHIAKI; MIKI TOSHIO

144

The two-dimensional periodic box–ball system and its fundamental cycle  

International Nuclear Information System (INIS)

We study a two-dimensional box–ball system which is an ultradiscrete analogue of the discrete KP equation. We construct an algorithm to calculate the fundamental cycle, which is an important conserved quantity of the two-dimensional box–ball system with periodic boundary condition, by using the tropical curve theory. (paper)

2012-10-05

145

Periodic solutions of certain third order nonlinear differential systems with delay  

International Nuclear Information System (INIS)

This paper investigates the existence of 2?-periodic solutions of systems of third-order nonlinear differential equations, with delay, under varied assumptions. The results obtained extend earlier works of Tejumola and generalize to third order systems those of Conti, Iannacci and Nkashama as well as DePascale and Iannacci and Iannacci and Nkashama. 16 refs

1990-01-01

146

Doubly periodic waves of a discrete nonlinear Schrodinger system with saturable nonlinearity  

Science.gov (United States)

A system of two discrete nonlinear Schr\\"odinger equations of the Ablowitz-Ladik type with a saturable nonlinearity is shown to admit a doubly periodic wave, whose long wave limit is also derived. As a by-product, several new solutions of the elliptic type are provided for NLS-type discrete and continuous systems.

Conte, Robert; Chow, K. W.

147

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.

2008-01-01

148

Partial monitoring system Radioactivity of the Environment (final report for the period 2000-2004)  

International Nuclear Information System (INIS)

[en] In this Final report for the period 2000-2004 the Partial monitoring system 'Radioactivity of the Environment' is presented. International co-operation of the Slovak Hydrometeorological Institute in the Partial monitoring system 'Radioactivity of the Environment' as well as financial data are reviewed

2004-01-01

149

Existence of positive periodic solution of mutualism system with several delays  

International Nuclear Information System (INIS)

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].

2002-01-00

150

Existence of positive periodic solution of mutualism system with several delays  

Energy Technology Data Exchange (ETDEWEB)

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].

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

151

Guaranteed Cost Fault-tolerant Controller Design of Networked Control Systems under Variable-period Sampling  

Directory of Open Access Journals (Sweden)

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.

Xuan Li; Xiao-Bei Wu

2009-01-01

152

On the rate of convergence of periodic solutions in perturbed autonomous systems as the perturbation vanishes  

CERN Multimedia

We consider an autonomous system in R^n having a limit cycle x_0 of period T>0 which is nondegenerate in a suitable sense. We then consider the perturbed system obtained by adding to the autonomous system a T-periodic, not necessarily differentiable, term whose amplitude tends to 0 as a small parameter e>0 tends to 0. Assuming the existence of a T-periodic solution x_e of the perturbed system and its convergence to x_0 as e->0, the paper establishes the existence of d_e->0 as e->0 such that \\|x_e(t+d_e)-x_0(t)\\|0 and any e>0 sufficiently small.

Makarenkov, Oleg

2007-01-01

153

Global chaos in a periodically forced, linear system with a dead-zone restoring force  

Energy Technology Data Exchange (ETDEWEB)

The Poincare mapping and the corresponding mapping sections for global motions in a linear system possessing a dead-zone restoring force are introduced through switching planes pertaining to two constraints. The global periodic motions based on the Poincare mapping are determined, and the eigenvalue analysis for the stability and bifurcation of periodic motion is carried out. Global chaos in such a system is investigated numerically from the unstable global periodic motions analytically determined. The bifurcation scenario with varying parameters is presented. The mapping structures of periodic and chaotic motions are discussed. The Poincare mapping sections for global chaos are given for illustration. The grazing phenomenon embedded in chaotic motion is observed in this investigation.

Luo, Albert C.J. E-mail: aluo@siue.edu; Menon, Santhosh E-mail: santhosh.menon@uconn.edu

2004-03-01

154

Confrontation between Quantized Periods of Some Extra-Solar Planetary Systems and Observations  

Directory of Open Access Journals (Sweden)

Full Text Available 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 planets, of stars having approximately the same mass as the sun, are chosen to apply the same relation. The differences between the observed and calculated periods for the extra-solar systems have been calculated and tabulated. It is found that the percentage errors between the predicted values and the corresponding observed values for extra-planetary systems are controlled by the star’s mass and its quantum number. The percentage error decreases by increasing the quantum number, for quantum numbers over 4. When the quantum number is less than or equal 4, it is found that the percentage error decreases by decreasing the quantum number.

A. B. Morcos

2013-01-01

155

Soliton excitations and periodic waves without dispersion relation in shallow water system  

International Nuclear Information System (INIS)

[en] 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

2003-01-01

156

Forecasting Data from Periodic Systems of Molecules, and Other Systematics, Using Regression and Neural Networks  

Science.gov (United States)

Early interpolations of intensity constants led to constructing a periodic system of diatomic molecules, analogous to the element periodic chart, and testing it against data of many properties. The axes of this system (the period and group numbers of the two atoms) have been employed to forecast various data using regression and neural networks. Kong has constructed a periodic system for triatomic molecules. Periodic behavior is also seen in many-atom species and data forecasts have resulted. The axes employed are the number of substituents (e.g. of halogens substituted in benzenes) or of added ligands (e.g. of oxides of transition metals); and the period number of the central, substituted, or ligand species. It is hoped that the spectroscopists will suggest planetary, stellar, and interstellar molecules for which estimated data, obtainable with these methods, are of interest to their community.R. Hefferlin and L. A. Kuznetsova, “Systematics of Diatomic Molecular Transition Moments,” J. Quant. Spectr. Radiative Transf. 62 (1999) 765-774.Ray Hefferlin, W. Bradford Davis, and Jason Ileto, “An Atlas of Forecasted Molecular Data I: Internuclear Separations of Main-Group and Transition-Metal Neutral Gas-Phase Diatomic Molecules in the Ground State,” J. Chem. Inf. Comput. Sci. 43 (2002) 622-628.W. Bradford Davis and Ray Hefferlin, “An Atlas of Forecasted Molecular Data II: Vibration frequencies of Main-Group and Transition-Metal Neutral Gas-Phase Diatomic Molecules in the Ground State,” J. Chem. Inf. Comput. Sci., in press.F.-A. Kong, in R. Hefferlin, Periodic Systems of Molecules and their Relation to the Systematic Analysis of Molecular Data, Edwin Mellen Press, Lewiston, New York, 1989, Chapter 11.Ken Luk, Ray Hefferlin, and Gabriel Johnson, “How Deep in Molecular Space can Periodicity be Found?” World Science and Engineering Academy and Society 9th WSEAS CSCC Multiconference, Vouliagmeni, Athens, Greece, July 13, 2005.

Hefferlin, Ray

2006-06-01

157

Linear stability analysis for periodic traveling waves of the Boussinesq equation and the KGZ system  

CERN Multimedia

The question for linear stability of spatially periodic waves for the Boussinesq equation (the cases $p=2,3$) and the Klein-Gordon-Zakharov system is considered. For a wide class of solutions, we completely and explicitly characterize their linear stability (instability respectively), when the perturbations are taken with the same period $T$. In particular, our results allow us to completely recover the linear stability results, in the limit $T\\to \\infty$, for the whole line case.

Hakkaev, Sevdzhan; Stefanov, Atanas

2012-01-01

158

New periodic solutions to a generalized Hirota-Satsuma coupled KdV system  

Science.gov (United States)

Using expansions in terms of the Jacobi elliptic cosine function and third Jacobi elliptic function, some new periodic solutions to the generalized Hirota-Satsuma coupled KdV system are obtained with the help of the algorithm Mathematica. These periodic solutions are also reduced to the bell-shaped solitary wave solutions and kink-shape solitary solutions. As special cases, we obtain new periodic solution, bell-shaped and kink-shaped solitary solutions to the well-known Hirota-Satsuma equations.

Yan, Qing-You; Zhang, Yu-Feng; Wei, Xiao-Peng

2003-02-01

159

Flow rate oscillation period values in a system of parallel steam generating channels  

International Nuclear Information System (INIS)

The results of the analysis of the experimental data on flow rate pulsations period in the system of vertical parallel steam generating channels having unheated inlet and outlet sections are presented. It is shown that there exists linear dependence between oscillations period in pulsations zone and coolant transport time over the channel length from the begin of heating upto upper collector. Empirical dependences for determining pulsation period values for pressures of 2-16 MPa, heat flux 0.35-0.75 MW/m2, mass rate- 200-600 kg/m2xs are suggested

1984-01-01

160

A review of transparent insulation systems and the evaluation of payback period for building applications  

Energy Technology Data Exchange (ETDEWEB)

Research and development of transparent insulation systems (TI-systems) has been ongoing for 20 years with transparent insulation materials (TIMs) used to replace standard opaque insulation materials. TIM not only performs similar functions to opaque insulation, reducing heat losses and controlling indoor temperatures, but allows solar transmittance of more than 50%. With a thickness of less than 20 cm, it can provide a financial return to building occupants when applied to building facades, maximising occupiable and sellable spaces in urban areas, without compromising thermal comfort within buildings. In this review of TI-systems for building applications, drawbacks to previous applications, cost trends, and analysis of the limitation in information from previous studies are discussed. A major drawback in the development of TI-systems identified is the lack of cost information; the payback periods for TI-systems used in previous renovation projects are virtually unknown. Simple payback period calculations were undertaken based on information available from a demonstration project documented by the Solar Heating and Cooling (SHC) Programme of the International Energy Agency (IEA) Task 20 'Solar Energy in Building Renovation'. The calculations indicated an encouraging 5-8-year payback period for this particular case study. It was concluded that the simple payback period calculation may be used for feasibility studies to indicate the time required to recoup investment when installing TI-systems and to provide initial guidance for building designers when evaluating the potential application of TI-systems in their buildings. (author)

Wong, I.L.; Perera, R.S. [Centre for Sustainable Technologies, University of Ulster, Newtownabbey, Co. Antrim BT37 0QB (United Kingdom); Eames, P.C. [Warwick Institute for Sustainable Energy and Resources, School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom)

2007-09-15

 
 
 
 
161

Global Behaviors and Optimal Harvesting of a Class of Impulsive Periodic Logistic Single-Species System with Continuous Periodic Control Strategy  

Directory of Open Access Journals (Sweden)

Full Text Available Global behaviors and optimal harvesting of a class of impulsive periodic logistic single-species system with continuous periodic control strategy is investigated. Four new sufficient conditions that guarantee the exponential stability of the impulsive evolution operator introduced by us are given. By virtue of exponential stability of the impulsive evolution operator, we present the existence, uniqueness and global asymptotical stability of periodic solutions. Further, the existence result of periodic optimal controls for a Bolza problem is given. At last, an academic example is given for demonstration.

Wang JinRong; Xiang X; Wei W

2008-01-01

162

Global Behaviors and Optimal Harvesting of a Class of Impulsive Periodic Logistic Single-Species System with Continuous Periodic Control Strategy  

Directory of Open Access Journals (Sweden)

Full Text Available Global behaviors and optimal harvesting of a class of impulsive periodic logistic single-species system with continuous periodic control strategy is investigated. Four new sufficient conditions that guarantee the exponential stability of the impulsive evolution operator introduced by us are given. By virtue of exponential stability of the impulsive evolution operator, we present the existence, uniqueness and global asymptotical stability of periodic solutions. Further, the existence result of periodic optimal controls for a Bolza problem is given. At last, an academic example is given for demonstration.

JinRong Wang; X. Xiang; W. Wei

2009-01-01

163

PERIOD CHANGE SIMILARITIES AMONG THE RR LYRAE VARIABLES IN OOSTERHOFF I AND OOSTERHOFF II GLOBULAR SYSTEMS  

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.

2011-01-01

164

Suppression and creation of chaos in a periodically forced Lorenz system  

International Nuclear Information System (INIS)

Periodic forcing is introduced into the Lorenz model to study the effects of time-dependent forcing on the behavior of the system. Such a nonautonomous system stays dissipative and has a bounded attracting set which all trajectories finally enter. The possible kinds of attracting sets are restricted to periodic orbits and strange attractors. A large-scale survey of parameter space shows that periodic forcing has mainly three effects in the Lorenz system depending on the forcing frequency: (i) Fixed points are replaced by oscillations around them; (ii) resonant periodic orbits are created both in the stable and the chaotic region; and (iii) chaos is created in the stable region near the resonance frequency and in periodic windows. A comparison to other studies shows that part of this behavior has been observed in simulations of higher truncations and real world experiments. Since very small modulations can already have a considerable effect, this suggests that periodic processes such as annual or diurnal cycles should not be omitted even in simple climate models

1179-01-00

165

The effect of volatile bubble growth rate on the periodic dynamics of shallow volcanic systems  

Directory of Open Access Journals (Sweden)

Full Text Available Many volcanic eruptions exhibit periodic behavior. For instance, periodic ground inflations and deflations in proximity to a volcano are the consequences of periodic overpressure variations in the magma conduit and periodic magma flow rate. The period varies from a few hours to many years, depending on the volcano parameters. On the other hand, volatile components exsolve from an ascending magma by forming bubbles. The strong dependence of the melt viscosity with the volatile concentration generates a positive feedback on the magma flow. We consider here the effect of the growth of volatile bubbles on the dynamics of a magmatic flow in a shallow volcanic system. Various expressions for the bubble growth rate are treated, thus generalizing previous work. In particular, a growth rate law derived from a recent many-bubble theory is considered. It is seen that, for a range of flow rate values at the base of the magma conduit, the system undergoes a Hopf bifurcation. Periodic solutions compatible with the observations are generated. This work shows that measurements of volcanic activity have the potential to test various bubble growth models in magmatic systems.

I. L'Heureux

2010-01-01

166

Periodic solutions for small and large delays in a tumor-immune system model  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper we study the Hopf bifurcation for the tumor-immune system model with one delay. This model is governed by a system of two differential equations with one delay. We show that the system may have periodic solutions for small and large delays for some critical value of the delay parameter via Hopf bifurcation theorem bifurcating from the non trivial steady state.

Radouane Yafia

2006-01-01

167

Numerical detection of unstable periodic orbits in continuous-time dynamical systems with chaotic behaviors  

Directory of Open Access Journals (Sweden)

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.

Y. Saiki

2007-01-01

168

Human error considerations and annunciator effects in determining optimal test intervals for periodically inspected standby systems  

International Nuclear Information System (INIS)

This paper incorporates the effects of four types of human error in a model for determining the optimal time between periodic inspections which maximizes the steady state availability for standby safety systems. Such safety systems are characteristic of nuclear power plant operations. The system is assumed to possess the following characteristics: (1) system failures occur according to a specified lifetime distribution, while on standby, which may have a time-dependent failure rate. The system may include a detection/annunciator device which will announce a failure with a known constant probability; (2) the system is periodically inspected for failures which may not have been detected by the annunciator; (3) four types of human errors may occur in the inspection/repair process: the system may not be correctly replaced on-line after inspection; repair (type A error); a failed system may be judged good during a periodic inspection (type B error); a failed system may be improperly repaired (type C error); or the failure causing an annunciator-activated inspection may not be located (type D error); (4) inspection times are assumed fixed and known; (5) repair times are assumed to have a lognormal distribution. The system described above is modeled by means of an infinite state-space Markov chain. The purpose of the paper is to demonstrate techniques for computing steady-state availability A and the optimal periodic inspection interval tau* for the system described above. The model can be used to investigate the effects of human error probabilities on optimal availability, study the benefits of annunciating the standby-system, and to determine optimal inspection intervals. Several examples which are representative of nuclear power plant applications are presented

1981-01-27

169

Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor-Blade Systems  

DEFF Research Database (Denmark)

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.

Christensen, Rene Hardam; Santos, Ilmar

2003-01-01

170

Bifurcation for Second-Order Hamiltonian Systems with Periodic Boundary Conditions  

Directory of Open Access Journals (Sweden)

Full Text Available Through variational methods, we study nonautonomous systems of second-order ordinary differential equations with periodic boundary conditions. First, we deal with a nonlinear system, depending on a function u, and prove that the set of bifurcation points for the solutions of the system is not σ-compact. Then, we deal with a linear system depending on a real parameter λ>0 and on a function u, and prove that there exists λ∗ such that the set of the functions u, such that the system admits nontrivial solutions, contains an accumulation point.

Francesca Faraci; Antonio Iannizzotto

2008-01-01

171

The vacuum system of the regular magnetic structure period of the UNK 1-st stage  

International Nuclear Information System (INIS)

There has been described the vacuum system for a period of the magnetic structure of the 1-st UNK stage. It is a periodically repeating structural unit of the vacuum chamber of the 1-st UNK stage. The results of testing the full-scale sector of the vacuum system showed the design of the vacuum chamber and vacuum equipment to be satisfactory for operation. The obtained pressure is equal to 2.6x10-8 Pa in the nitrogen equivalent of Coulomb scattering, that is much less than the value required for the UNK (1.3x10-7 Pa). 8 refs.; 3 figs

1991-01-01

172

Human error considerations and annunciator effects in determining optimal test intervals for periodically inspected standby systems  

Energy Technology Data Exchange (ETDEWEB)

This paper incorporates the effects of four types of human error in a model for determining the optimal time between periodic inspections which maximizes the steady state availability for standby safety systems. Such safety systems are characteristic of nuclear power plant operations. The system is modeled by means of an infinite state-space Markov chain. Purpose of the paper is to demonstrate techniques for computing steady-state availability A and the optimal periodic inspection interval tau* for the system. The model can be used to investigate the effects of human error probabilities on optimal availability, study the benefits of annunciating the standby-system, and to determine optimal inspection intervals. Several examples which are representative of nuclear power plant applications are presented.

McWilliams, T.P.; Martz, H.F.

1981-01-01

173

Normal forms and complex periodic orbits in semiclassical expansions of Hamiltonian systems  

CERN Document Server

Bifurcations of periodic orbits as an external parameter is varied are a characteristic feature of generic Hamiltonian systems. Meyer's classification of normal forms provides a powerful tool to understand the structure of phase space dynamics in their neighborhood. We provide a pedestrian presentation of this classical theory and extend it by including systematically the periodic orbits lying in the complex plane on each side of the bifurcation. This allows for a more coherent and unified treatment of contributions of periodic orbits in semiclassical expansions. The contribution of complex fixed points is find to be exponentially small only for a particular type of bifurcation (the extremal one). In all other cases complex orbits give rise to corrections in powers of $\\hbar$ and, unlike the former one, their contribution is hidden in the ``shadow'' of a real periodic orbit.

Leboeuf, P

1998-01-01

174

Analytical stability analysis of periodic systems by Poincaré mappings with application to rotorcraft dynamics  

Directory of Open Access Journals (Sweden)

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.

Flashner Henryk; Guttalu Ramesh S.

1997-01-01

175

Disk-planets interactions and the diversity of period ratios in Kepler's multi-planetary systems  

CERN Multimedia

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 intriguing 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 ten days, for which tidal circularization is unlikely to provide efficient divergent evolution of the planets orbits. 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 part...

Baruteau, Clement

2013-01-01

176

Variables Scaling to Solve a Singular Bifurcation Problem with Applications to Periodically Perturbed Autonomous Systems  

CERN Multimedia

By means of a linear scaling of the variables we convert a singular bifurcation equation in $\\R^n$ into an equivalent equation to which the classical implicit function theorem can be directly applied. This allows to deduce the existence of a unique branch of solutions as well as a relevant property of the spectrum of the derivative of the singular bifurcation equation along the branch. We use these results to show the existence, uniqueness and the asymptotic stability of periodic solutions of a $T$-periodically perturbed autonomous system bifurcating from a $T$-periodic limit cycle of the autonomous unperturbed system. This problem is classical, but the novelty of the method proposed is that it allows us to solve the problem without any reduction of the dimension of the state space as it is usually done in the literature by means of the Lyapunov-Schmidt method.

Kamenskii, Mikhail; Nistri, Paolo

2009-01-01

177

Validation of a model for a residential heat pump system based on short-period measurements  

Energy Technology Data Exchange (ETDEWEB)

To improve the performance of a heat pump system and hence to provide a contribution to the quality assurance of heat pump systems, the application of modern model-based control techniques as well as model-based fault detection and diagnosis methods is imperative. This paper describes the derivation and validation of a low-order dynamic model of a widely used residential heat pump heating system together with its building. The parameters of the model are identified based on short-period measurements. In the case of model-based fault detection, they allow the quantification of the differences between the planned and the installed system after very brief test periods. (orig.)

Shafai, E.; Ginsburg, S.; Wimmer, R.; Zogg, D. [Measurement and Control Lab., Swiss Federal Inst. of Tech. (ETH), Zuerich (Switzerland)

1999-07-01

178

[Integrative analytic prediction systems in treating a patient in the acute period of ischemic stroke  

UK PubMed Central (United Kingdom)

Basing on the results of the analysis of the main clinical-paraclinical syndromes of ischemic stroke in its acute period, two integrative analytic-prognostic systems have been designed. These systems improve quality of disease prognosis. More accurate prognosis is achieved by the model, which shows that outcome of ischemic stroke depends both on the initial condition of the disease and on its dynamics in the acutest period. The computerized system of early prognosis of ischemic stroke allows to give a detailed prognosis of complications and outcome of the disease. The use of the computerized system of early prognosis helps to gain the reliable improvement in groups of moderately severe and severe ischemic stroke.

Ershov VI; Burdakov VV; Utkin SA

2006-01-01

179

[Integrative analytic prediction systems in treating a patient in the acute period of ischemic stroke].  

Science.gov (United States)

Basing on the results of the analysis of the main clinical-paraclinical syndromes of ischemic stroke in its acute period, two integrative analytic-prognostic systems have been designed. These systems improve quality of disease prognosis. More accurate prognosis is achieved by the model, which shows that outcome of ischemic stroke depends both on the initial condition of the disease and on its dynamics in the acutest period. The computerized system of early prognosis of ischemic stroke allows to give a detailed prognosis of complications and outcome of the disease. The use of the computerized system of early prognosis helps to gain the reliable improvement in groups of moderately severe and severe ischemic stroke. PMID:18196626

Ershov, V I; Burdakov, V V; Utkin, S A

2006-01-01

180

New periodic and soliton wave solutions for the generalized Zakharov system and (2 + 1)-dimensional Nizhnik-Novikov-Veselov system  

International Nuclear Information System (INIS)

In this paper, the Exp-function method is used to obtain generalized solitonary solutions and periodic solutions of the Generalized Zakharov system and (2 + 1)-dimensional Nizhnik-Novikov-Veselov system. It is shown that the Exp-function method, with the help of symbolic computation, provides a powerful mathematical tool for solving nonlinear evolution equations in mathematical physics.

2009-11-15

 
 
 
 
181

Infrared photometry of the RS CVn short-period systems - XY UMa and WY Cnc  

Energy Technology Data Exchange (ETDEWEB)

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.

Arevalo, M.J.; Lazaro, C. (Instituto de Astrofisica de Canarias, La Laguna (Spain))

1990-03-01

182

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

1990-01-01

183

Multiple periodic solutions for a fourth-order discrete Hamiltonian system  

Directory of Open Access Journals (Sweden)

Full Text Available By means of a three critical points theorem proposed by Brezis and Nirenberg and a general version of Mountain Pass Theorem, we obtain some multiplicity results for periodic solutions of a fourth-order discrete Hamiltonian system ?4u(t-2)+? F(t,u(t))=0 for all t? Z.

Jianwen Zhou; Yongkun Li

2010-01-01

184

Periodic solutions for nonautonomous second order Hamiltonian systems with sublinear nonlinearity  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Some existence and multiplicity of periodic solutions are obtained for nonautonomous second order Hamiltonian systems with sublinear nonlinearity by using the least action principle and minimax methods in critical point theory. Mathematics Subject Classification (2000): 34C25, 37J45, 58E50.

Wang Zhiyong; Zhang Jihui

2011-01-01

185

Doubly periodic waves of a discrete nonlinear Schrödinger system with saturable nonlinearity  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A system of two discrete nonlinear Schrödinger equations of the Ablowitz-Ladik type with a saturable nonlinearity is shown to admit a doubly periodic wave, whose long wave limit is also derived. As a by-product, several new solutions of the elliptic type are provided for NLS-type discrete and contin...

Conte, R; Chow, KW

186

Time evolution of two-level systems driven by periodic fields  

Science.gov (United States)

We describe a method to compute perturbative expansions for two-level systems driven by periodic time-dependent fields. Our expansions do not contain secular terms being, therefore, convenient for the study of long-time properties. We apply the method to the case of ac-dc fields and analyse situations where an approximate effect of dynamical localisation is exhibited.

Barata, J. C. A.; Cortez, D. A.

2002-09-01

187

Existence of positive almost periodic solutions for delay Lotka-Volterra cooperative systems  

Directory of Open Access Journals (Sweden)

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.

Kaihong Zhao; Juqing Liu

2013-01-01

188

Four positive periodic solutions of a discrete time Lotka-Volterra competitive system with harvesting terms  

Directory of Open Access Journals (Sweden)

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.

Xinggui Liu; Yaping Ren; Yongkun Li

2011-01-01

189

Twin periodic solutions of predator-prey dynamic system on time scales  

Directory of Open Access Journals (Sweden)

Full Text Available In this article, we consider a delayed predator-prey dynamic system with type IV functional responses on time scales. Sufficient criteria for the existence of at least two periodic solutions are established by using the well-known continuation theorem due to Mawhin. An example is given to illustrate the main result.

Rong-Hua He; Hong-Xu Li; Liang Zhang

2009-01-01

190

Stochastic Long Term Modelling of a Drainage System with Estimation of Return Period Uncertainty  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 bo...

Thorndahl, Søren

191

Uniform exponential stability of linear periodic systems in a Banach space  

Directory of Open Access Journals (Sweden)

Full Text Available This article is devoted to the study of linear periodic dynamical systems, possessing the property of uniform exponential stability. It is proved that if the Cauchy operator of these systems possesses a certain compactness property, then the asymptotic stability implies the uniform exponential stability. We also show applications to different classes of linear evolution equations, such as ordinary linear differential equations in the space of Banach, retarded and neutral functional differential equations, some classes of evolution partial differential equations.

David N. Cheban

2001-01-01

192

Standing, Periodic and Solitary Waves in (1 + 1)-Dimensional Caudry-Dodd-Gibbon-Sawada-Kortera System  

International Nuclear Information System (INIS)

In the paper, the variable separation approach, homoclinic test technique and bilinear method are successfully extended to a (1 + 1)-dimensional Caudry-Dodd-Gibbon-Sawada-Kortera (CDGSK) system, respectively. Based on the derived exact solutions, some significant types of localized excitations such as standing waves, periodic waves, solitary waves are simultaneously derived from the (1 + 1)-dimensional Caudry-Dodd-Gibbon-Sawada-Kortera system by entrancing appropriate parameters. (general)

2010-12-15

193

Periodic solutions of o.d.e. systems with a lipchitz non linearity  

CERN Multimedia

In this report, we address differential systems with Lipschitz non linearities; this study is motivated by the subject of vibrations of structures with unilateral springs or non linear stress-strain law close to the linear case. We consider existence and solution with fixed point methods; this method is constructive and provides a numerical algorithm which is under study. We describe the method for a static case example and we address periodic solutions of differential systems arising in the vibration of structures.

Rousselet, Bernard

2011-01-01

194

Anomalous Edge States and the Bulk-Edge Correspondence for Periodically Driven Two-Dimensional Systems  

Science.gov (United States)

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.

Rudner, Mark S.; Lindner, Netanel H.; Berg, Erez; Levin, Michael

2013-07-01

195

Investigation of unstable periodic space-time states in distributed active system with supercritical current  

International Nuclear Information System (INIS)

[en] The set of the unstable periodic space-time states, characterizing the chaotic space-time dynamics of the electron beam with the supercritical current in the Pierce diode is discussed. The Lyapunov indicators of the revealed instable space-time states of the chaotic dynamics of the distributed self-excited system are calculated. It is shown that change in the set of the unstable periodic states in dependence on the Pierce parameter is determined by change in the various orbits stability, which is demonstrated by the values of senior Lyapunov unstable state index[ru] ?????????? ????? ???????????? ????????????? ???????????????-????????? ?????????, ??????????????? ??????????? ???????????????-????????? ???????? ???????????? ????? ?? ???????????????? ????? ? ????? ?????. ?????????? ???????????? ??????????? ?????????? ?????????? ???????????? ???????????????-????????? ????????? ??????????? ???????? ?????????????? ????????????????? ???????. ????????, ??? ????????? ?????? ???????????? ????????????? ????????? ? ??????????? ?? ????????? ????? ???????????? ?????????? ???????????? ????????? ?????, ??? ????????????????? ?????????? ???????? ???????????? ?????????? ????????????? ?????????

2003-01-01

196

Continuous time random walks in periodic systems: fluid limit and fractional differential equations on the circle  

International Nuclear Information System (INIS)

In this paper, the continuous time random walk on the circle is studied. We derive the corresponding generalized master equation and discuss the effects of topology, especially important when Levy flights are allowed. Then, we work out the fluid limit equation, formulated in terms of the periodic version of the fractional Riemann-Liouville operators, for which we provide explicit expressions. Finally, we compute the propagator in some simple cases. The analysis presented herein should be relevant when investigating anomalous transport phenomena in systems with periodic dimensions.

2007-11-09

197

Time-Periodic Solutions in an Einstein AdS-Massless-Scalar-Field System.  

UK PubMed Central (United Kingdom)

We construct time-periodic solutions for a system of a self-gravitating massless scalar field, with a negative cosmological constant, in d+1 spacetime dimensions at spherical symmetry, both perturbatively and numerically. We estimate the convergence radius of the formally obtained perturbative series and argue that it is greater then zero. Moreover, this estimate coincides with the boundary of the convergence domain of our numerical method and the threshold for the black-hole formation. Then we confirm our results with a direct numerical evolution. This also gives strong evidence for the nonlinear stability of the constructed time-periodic solutions.

Maliborski M; Rostworowski A

2013-08-01

198

Multiple Periodic Solutions for Some Classes of First-Order Hamiltonian Systems  

Directory of Open Access Journals (Sweden)

Full Text Available Considering a decomposition R2N=A?B of R2N , we prove in this work, the existence of at least (1+dimA) geometrically distinct periodic solutions for the first-order Hamiltonian system Jx'(t)+H'(t,x(t))+e(t)=0 when the Hamiltonian H(t,u+v) is periodic in (t,u) and its growth at infinity in v is at most like or faster than |v|a, 0?ae is a forcing term. For the proof, we use the Least Action Principle and a Generalized Saddle Point Theorem.

Mohsen Timoumi

2011-01-01

199

Time-Periodic Solutions in an Einstein AdS-Massless-Scalar-Field System.  

Science.gov (United States)

We construct time-periodic solutions for a system of a self-gravitating massless scalar field, with a negative cosmological constant, in d+1 spacetime dimensions at spherical symmetry, both perturbatively and numerically. We estimate the convergence radius of the formally obtained perturbative series and argue that it is greater then zero. Moreover, this estimate coincides with the boundary of the convergence domain of our numerical method and the threshold for the black-hole formation. Then we confirm our results with a direct numerical evolution. This also gives strong evidence for the nonlinear stability of the constructed time-periodic solutions. PMID:23952381

Maliborski, Maciej; Rostworowski, Andrzej

2013-08-02

200

Time-periodic solutions in Einstein AdS - massless scalar field system  

CERN Document Server

We construct time-periodic solutions for a system of self-gravitating massless scalar field, with negative cosmological constant, in d+1 spacetime dimensions at spherical symmetry, both perturbatively and numerically. We estimate the convergence radius of the formally obtained perturbative series and argue that it is greater then zero. Moreover, this estimate coincides with the boundary of the convergence domain of our numerical method and the threshold for the black-hole formation. Then we confirm our results with a direct numerical evolution. This also gives strong evidence for nonlinear stability of the constructed time-periodic solutions.

Maliborski, Maciej

2013-01-01

 
 
 
 
201

Time-Periodic Solutions in an Einstein AdS–Massless-Scalar-Field System  

Science.gov (United States)

We construct time-periodic solutions for a system of a self-gravitating massless scalar field, with a negative cosmological constant, in d+1 spacetime dimensions at spherical symmetry, both perturbatively and numerically. We estimate the convergence radius of the formally obtained perturbative series and argue that it is greater then zero. Moreover, this estimate coincides with the boundary of the convergence domain of our numerical method and the threshold for the black-hole formation. Then we confirm our results with a direct numerical evolution. This also gives strong evidence for the nonlinear stability of the constructed time-periodic solutions.

Maliborski, Maciej; Rostworowski, Andrzej

2013-08-01

202

Resolution of identity approximation for the Coulomb term in molecular and periodic systems.  

UK PubMed Central (United Kingdom)

A new formulation of resolution of identity approximation for the Coulomb term is presented, which uses atom-centered basis and auxiliary basis functions and treats molecular and periodic systems of any dimensionality on an equal footing. It relies on the decomposition of an auxiliary charge density into charged and chargeless components. Applying the Coulomb metric under periodic boundary conditions constrains the explicit form of the charged part. The chargeless component is determined variationally and converged Coulomb lattice sums needed for its determination are obtained using chargeless linear combinations of auxiliary basis functions. The lattice sums are partitioned in near- and far-field portions which are treated through an analytical integration scheme employing two- and three-center electron repulsion integrals and multipole expansions, respectively, operating exclusively in real space. Our preliminary implementation within the TURBOMOLE program package demonstrates consistent accuracy of the method across molecular and periodic systems. Using common auxiliary basis sets the errors of the approximation are small, in average about 20 muhartree per atom, for both molecular and periodic systems.

Burow AM; Sierka M; Mohamed F

2009-12-01

203

Resolution of identity approximation for the Coulomb term in molecular and periodic systems  

Science.gov (United States)

A new formulation of resolution of identity approximation for the Coulomb term is presented, which uses atom-centered basis and auxiliary basis functions and treats molecular and periodic systems of any dimensionality on an equal footing. It relies on the decomposition of an auxiliary charge density into charged and chargeless components. Applying the Coulomb metric under periodic boundary conditions constrains the explicit form of the charged part. The chargeless component is determined variationally and converged Coulomb lattice sums needed for its determination are obtained using chargeless linear combinations of auxiliary basis functions. The lattice sums are partitioned in near- and far-field portions which are treated through an analytical integration scheme employing two- and three-center electron repulsion integrals and multipole expansions, respectively, operating exclusively in real space. Our preliminary implementation within the TURBOMOLE program package demonstrates consistent accuracy of the method across molecular and periodic systems. Using common auxiliary basis sets the errors of the approximation are small, in average about 20 ?hartree per atom, for both molecular and periodic systems.

Burow, Asbjörn M.; Sierka, Marek; Mohamed, Fawzi

2009-12-01

204

Exact-Exchange Kohn-Sham formalism applied to one-dimensional periodic electronic systems  

CERN Document Server

The Exact-Exchange Kohn-Sham formalism, which treats exchange interactions exactly within density-functional theory, is applied to one-dimensional periodic systems. The underlying implementation does not rely on specific symmetries of the considered system and can be applied to any kind of periodic structure in one- to three dimensions. As a test system, $trans$-polyacetylene, both in form of an isolated chain and in the bulk geometry has been investigated. Within this scheme, bandstructures and independent particle response functions are calculated and compared to experimental data as well as to data calculated via several other methods. Compared to results from the local-density approximation, the exact-exchange method leads to an increased value for the band gap, as it has already been observed for three dimensional semiconductors. An inclusion of correlation potentials within the local density approximation or generalized gradient approximations leads to only negligible effects in the bandstructure. The e...

Rohra, S; Görling, A; Rohra, Stefan; Engel, Eberhard; Goerling, Andreas

2005-01-01

205

Local ab initio methods for calculating optical bandgaps in periodic systems. II. Periodic density fitted local configuration interaction singles method for solids  

Science.gov (United States)

We present a density fitted local configuration interaction singles (CIS) method for calculating optical bandgaps in 3D-periodic systems. We employ an Ewald technique to carry out infinite lattice summations for the exciton-exciton interaction, and robust product-density specific local density fitting in direct space for the electron-hole interaction. Moreover, we propose an alternative to the usual cyclic model with Born-von Karman periodic boundary conditions, the so called Wigner-Seitz supercell truncated infinite model, which exhibits much improved convergence of the CIS excitation energy with respect to the size of the supercell. Test calculations on a series of prototypical systems demonstrate that the method at the present stage can be used to calculate the excitonic bandgaps of 3D periodic systems with up to a dozen atoms in the unit cell, ranging from wide-gap insulators to semiconductors.

Lorenz, Marco; Maschio, Lorenzo; Schütz, Martin; Usvyat, Denis

2012-11-01

206

Planetary period magnetic field oscillations in Saturn's magnetosphere: Postequinox abrupt nonmonotonic transitions to northern system dominance  

Science.gov (United States)

We examine the "planetary period" magnetic field oscillations observed in the "core" region of Saturn's magnetosphere (dipole L ? 12), on 56 near-equatorial Cassini periapsis passes that took place between vernal equinox in August 2009 and November 2012. Previous studies have shown that these consist of the sum of two oscillations related to the northern and southern polar regions having differing amplitudes and periods that had reached near-equal amplitudes and near-converged periods ~10.68 h in the interval to ~1 year after equinox. The present analysis shows that an interval of strongly differing behavior then began ~1.5 years after equinox, in which abrupt changes in properties took place at ~6- to 8-month intervals, with three clear transitions occurring in February 2011, August 2011, and April 2012, respectively. These are characterized by large simultaneous changes in the amplitudes of the two systems, together with small changes in period about otherwise near-constant values of ~10.63 h for the northern system and ~10.69 h for the southern (thus, not reversed postequinox) and on occasion jumps in phase. The first transition produced a resumption of strong southern system dominance unexpected under northern spring conditions, while the second introduced comparably strong northern system dominance for the first time in these data. The third resulted in suppression of all core oscillations followed by re-emergence of both systems on a time scale of ~85 days, with the northern system remaining dominant but not as strongly as before. This behavior poses interesting questions for presently proposed theoretical scenarios.

Provan, G.; Cowley, S. W. H.; Sandhu, J.; Andrews, D. J.; Dougherty, M. K.

2013-06-01

207

Uniform exponential stability of linear almost periodic systems in Banach spaces  

Directory of Open Access Journals (Sweden)

Full Text Available This article is devoted to the study linear non-autonomous dynamical systems possessing the property of uniform exponential stability. We prove that if the Cauchy operator of these systems possesses a certain compactness property, then the uniform asymptotic stability implies the uniform exponential stability. For recurrent (almost periodic) systems this result is precised. We also show application for different classes of linear evolution equations: ordinary linear differential equations in a Banach space, retarded and neutral functional differential equations, and some classes of evolution partial differential equations.

David N. Cheban

2000-01-01

208

Self-isospectral tri-supersymmetry in PT-symmetric quantum systems with pure imaginary periodicity  

CERN Multimedia

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.

Correa, Francisco

2012-01-01

209

Self-isospectral tri-supersymmetry in PT-symmetric quantum systems with pure imaginary periodicity  

Science.gov (United States)

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.

Correa, Francisco; Plyushchay, Mikhail S.

2012-06-01

210

Phlegmasia cerulea dolens in patient with systemic lupus erythematosus in the remote postpartum period.  

UK PubMed Central (United Kingdom)

Vascular manifestations are not rare in systemic lupus erythematosus and, in most cases, are associated with antiphospholipid antibodies. Phlegmasia cerulea dolens is an unusual and severe complication of deep venous thrombosis of the lower limbs, which has a high mortality rate. In the literature, only two cases of phlegmasia cerulea dolens associated with primary antiphospholipid syndrome have been reported, but none associated with systemic lupus erythematosus. We report one case of phlegmasia cerulea dolens with rapid evolution to death in a patient with systemic lupus erythematosus in the remote postpartum period.

Marques Filho J

2011-09-01

211

Positive almost periodic solutions for state-dependent delay Lotka-Volterra competition systems  

Directory of Open Access Journals (Sweden)

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 $$ dot{u}_i(t)=u_i(t)Big[r_i(t)-a_{ii}(t)u_i(t) -sum_{j=1, jeq i}^na_{ij}(t)u_jig(t-au_j(t,u_1(t), dots,u_n(t))ig)Big], $$ 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.

Yongkun Li; Chao Wang

2012-01-01

212

The RR Lyrae Period-Luminosity-(Pseudo-)Color and Period-Color-(Pseudo-)Color Relations in the Str\\"omgren Photometric System: Theoretical Calibration  

CERN Multimedia

We present a theoretical calibration of the RR Lyrae period-luminosity-color and period-color-color relations in the multiband uvby Stroemgren photometric system. Our theoretical work is based on calculations of synthetic horizontal branches (HBs) for four different metallicities, fully taking into account evolutionary effects for a wide range in metallicities and HB morphologies. While our results show that "pure" period-luminosity and period-color relations do not exist in the Stroemgren system, which is due to the large scatter that is brought about by evolutionary effects when the uvby bandpasses are used, they also reveal that such scatter can be almost completely taken into account by incorporating Stroemgren pseudo-color [C_0 = (u-v)_0 - (v-b)_0] terms into those equations, thus leading to tight period-luminosity-{\\em pseudo}-color (PLpsC) and period-color-{\\em pseudo}-color (PCpsC) relations. We provide the latter in the form of analytical fits, so that they can be applied with high precision even in ...

Cortés, C

2008-01-01

213

Development of an arc-shaped precipitation system during the pre-monsoon period in Bangladesh  

Science.gov (United States)

A numerical simulation is performed to understand the features and development processes of the arc-shaped precipitation system that dominates in Bangladesh during the pre-monsoon (March-May) period. An arc-shaped precipitation system of 26 April 2002 is simulated using the Cloud Resolving Storm Simulator (CReSS) with a horizontal grid increment of 2 km. The Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model is used for downscaling. Hourly outputs of the finest domain (grid increment of 5 km) of MM5 and National Oceanic and Atmospheric Administration Reynolds weekly mean sea surface temperature data are used as the initial and boundary conditions for CReSS. Younger and more intense cells are formed in the southwestern end of the system. These cells move northeastward and merge with the system producing intense rainfalls. Simulation results indicate that low-level southwesterly or southerly wind brings warm moist air from the Bay of Bengal and helps develop new cells. The propagation speed of the system is 8 m/s, and the northeastern end moves faster than the southwestern end, creating clockwise rotation of the system. The propagation speed and the rotation of the simulated system coincide well with radar observations. The clockwise rotation of the system can be explained by the stronger (weaker) outflow and weaker (stronger) inflow in the northeastern (southwestern) end. The propagation of the system is attributable to the weak (?7 m/s, storm relative) rear-to-front flow in the moist environment. Thus, the arc-shaped precipitation system common to the pre-monsoon period in Bangladesh develops through a balance of strong southwesterly or southerly moist inflow in the low altitudes below 2 km and relatively weak outflow in the rear of the system.

Rafiuddin, M.; Uyeda, Hiroshi; Kato, Masaya

2013-05-01

214

Amplification effects on the transmission and reflexion phases in 1D periodic systems  

International Nuclear Information System (INIS)

We investigate the localization recently observed for locally non-hermitian Hamiltonians by studying the effect of the amplification on the scaling behavior of the transmission and reflection phases in 1D periodic chains of ?-potentials. The amplification here is represented by an imaginary term added to the on-site potential. It is found that both phases of the transmission and reflection amplitudes are strongly affected by the amplification term. In particular, the phases in the region of amplification become independent of the length scale while they oscillate strongly near the maximum transmission (or reflection). The interference effects on the phase in passive systems are used to interpret those observed in the presence of amplification. The phases of the transmission and reflection are found to oscillate in passive systems with increasing periods in the allowed band for the transmission phase while for the reflection phase, its initial value is always less than ?/2 in this band. (author)

1999-01-01

215

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.).

1994-01-01

216

Periodic Surveillance Testing Improvement Approach for the Digital Plant Protection System  

International Nuclear Information System (INIS)

Periodic Surveillance Testing (PST) Improvement Project is being performed by Korea Power Eng. Company, Inc. (KOPEC) as a contractor of Korea Hydro and Nuclear Power Co. Ltd (KHNP) together with Westinghouse Electric Company LLC (WEC) as a subcontractor. Plant Protection System (PPS) is not required during normal operation. Thus, the integrity of the PPS shall be confirmed via the periodic tests. However, the testing of Digital Plant Protection System (DPPS) takes too long time compared to that of the analog PPS. The excessive testing time imposes too much burden on the plant operator and could be a cause of human error. Thus, the test improvement for DPPS is needed to reduce the testing time. The improvement approach for the DPPS PST provides the recommended surveillance improvement to make the testing time shorten.

2008-01-01

217

Periodic Surveillance Testing Improvement Approach for the Digital Plant Protection System  

Energy Technology Data Exchange (ETDEWEB)

Periodic Surveillance Testing (PST) Improvement Project is being performed by Korea Power Eng. Company, Inc. (KOPEC) as a contractor of Korea Hydro and Nuclear Power Co. Ltd (KHNP) together with Westinghouse Electric Company LLC (WEC) as a subcontractor. Plant Protection System (PPS) is not required during normal operation. Thus, the integrity of the PPS shall be confirmed via the periodic tests. However, the testing of Digital Plant Protection System (DPPS) takes too long time compared to that of the analog PPS. The excessive testing time imposes too much burden on the plant operator and could be a cause of human error. Thus, the test improvement for DPPS is needed to reduce the testing time. The improvement approach for the DPPS PST provides the recommended surveillance improvement to make the testing time shorten.

Choi, Woong Seock; Lee, Yoon Hee; Kwon, Jong Soo; Han, Suk Gyu [Korea Power Engineering Company Inc., Daejeon (Korea, Republic of)

2008-10-15

218

Amplification Effects on the Transmission and Reflexion Phases in 1D Periodic Systems  

CERN Document Server

We investigate the localization observed recently for locally non-hermitian Hamiltonians by studying the effect of the amplification on the scaling behavior of the transmission and reflection phases in 1D periodic chains of added to the on-site potential. It is found that both phases of the transmission and reflection amplitudes are strongly affected by the amplification term. In particular, the phases in the region of amplification become independent of the length scale while they oscillate strongly near the maximum transmission (or reflection). The interference effects on the phase in passive systems are used to interpret those observed in the presence of amplification. The phases of the transmission and reflection are found to oscillate in passive systems whith increasing periods in the allowed band for the transmission phase while for the reflection phase, its initial value is always less than $\\pi /2$ in this band.

Zekri, N; Maarouf, S

1999-01-01

219

Reverse resonance in stock prices of financial system with periodic information.  

UK PubMed Central (United Kingdom)

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.

Li JC; Mei DC

2013-07-01

220

A lack of short-period multiplanet systems with close-proximity pairs and the curious case of Kepler 42  

CERN Document Server

Many Kepler multiplanet systems have planet pairs near low-order, mean-motion resonances. In addition, many Kepler multiplanet systems have planets with orbital periods less than a few days. With the exception of Kepler-42, however, there are no examples of systems with both short orbital periods and nearby companion planets while our modeling predicts ~17 such pairs. For orbital periods of the inner planet that are less than three days, the minimum period ratio of adjacent planet pairs follows the rough constraint P_2/P_1 >~ 2.3 (P_1/day)^(-2/3). This excess is not due to a lack of planets with short orbital periods. We also show a statistically significant excess of small, single candidate systems with orbital periods below 3 days over the number of multiple candidate systems with similar periods---perhaps a small-planet counterpart to the hot Jupiters.

Steffen, Jason H

2013-01-01

 
 
 
 
221

Performance of Thomas-Fermi and linear response approaches in periodic two-dimensional systems  

International Nuclear Information System (INIS)

A study of the performance of Thomas-Fermi and linear response theories in the case of a two-dimensional periodic model system is presented. The calculated density distribution and total energy per unit cell compare very well with exact results except when there is a small number of particles per cell, even though the potential has narrow tight-binding bands. The results supplement earlier findings of Koivisto and Stott for a localized impurity in a two-dimensional uniform gas.

2010-04-16

222

XIX Mendeleev Congress on general and applied chemistry. Abstract book in 4 volumes. Volume 3. Chemistry and technology of materials, including nanomaterials. Physico-chemical basis of metallurgical processes. Topical problems of chemical industry, evaluation of technical risks  

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

2011-01-01

223

Long-Period Objects in the Extrasolar Planetary Systems 47 Ursae Majoris and 14 Herculis  

Science.gov (United States)

The possible existence of additional long-period planetary-mass objects in the extrasolar planetary systems 47 UMa and 14 Her is investigated. We combine all available radial velocity data on these stars, spanning up to 18 yr. For the 47 UMa system, we show that while a second planet improves the fit to all available data, there is still substantial ambiguity as to the orbital parameters of the proposed planetary companion 47 UMa c. We also present new observations that clearly support a long-period companion in the 14 Her system. With a period of 6906+/-70 days, 14 Her c may be in a 4:1 resonance with the inner planet. We also present revised orbital solutions for seven previously known planets, incorporating recent additional data obtained with the 2.7 m Harlan J. Smith Telescope at McDonald Observatory. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

Wittenmyer, Robert A.; Endl, Michael; Cochran, William D.

2007-01-01

224

THE HD 192263 SYSTEM: PLANETARY ORBITAL PERIOD AND STELLAR VARIABILITY DISENTANGLED  

Energy Technology Data Exchange (ETDEWEB)

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 {approx}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 R{sub J} , and as small as 0.79 R{sub J} .

Dragomir, Diana; Matthews, Jaymie M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T1Z1 (Canada); Kane, Stephen R.; Ciardi, David R.; Von Braun, Kaspar [NASA Exoplanet Science Institute, Caltech, MS 100-22, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Henry, Gregory W. [Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Blvd., Box 9501, Nashville, TN 37209 (United States); Fischer, Debra A. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Howard, Andrew W. [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Jensen, Eric L. N. [Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA 19081 (United States); Laughlin, Gregory [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Mahadevan, Suvrath; Pilyavsky, Genady; Wang, Sharon X.; Wright, Jason T., E-mail: diana@phas.ubc.ca [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

2012-07-20

225

On stability zones for discrete-time periodic linear Hamiltonian systems  

Directory of Open Access Journals (Sweden)

Full Text Available The main purpose of the paper is to give discrete-time counterpart for some strong (robust) stability results concerning periodic linear Hamiltonian systems. In the continuous-time version, these results go back to Liapunov and ?ukovskii; their deep generalizations are due to Kre?n, Gel'fand, and Jakubovi? and obtaining the discrete version is not an easy task since not all results migrate mutatis-mutandis from continuous time to discrete time, that is, from ordinary differential to difference equations. Throughout the paper, the theory of the stability zones is performed for scalar (2nd-order) canonical systems. Using the characteristic function, the study of the stability zones is made in connection with the characteristic numbers of the periodic and skew-periodic boundary value problems for the canonical system. The multiplier motion (“traffic”) on the unit circle of the complex plane is analyzed and, in the same context, the Liapunov estimate for the central zone is given in the discrete-time case.

Vladimir R?svan

2006-01-01

226

On stability zones for discrete-time periodic linear Hamiltonian systems  

Directory of Open Access Journals (Sweden)

Full Text Available The main purpose of the paper is to give discrete-time counterpart for some strong (robust) stability results concerning periodic linear Hamiltonian systems. In the continuous-time version, these results go back to Liapunov and ?ukovskii; their deep generalizations are due to Kre?n, Gel'fand, and Jakubovi? and obtaining the discrete version is not an easy task since not all results migrate mutatis-mutandis from continuous time to discrete time, that is, from ordinary differential to difference equations. Throughout the paper, the theory of the stability zones is performed for scalar (2nd-order) canonical systems. Using the characteristic function, the study of the stability zones is made in connection with the characteristic numbers of the periodic and skew-periodic boundary value problems for the canonical system. The multiplier motion ("traffic") on the unit circle of the complex plane is analyzed and, in the same context, the Liapunov estimate for the central zone is given in the discrete-time case.

R?svan Vladimir

2006-01-01

227

Influence of Cropping Systems on Soil Aggregate and Weed Seedbank Dynamics During the Organic Transition Period  

UK PubMed Central (United Kingdom)

Agronomic management during the 3-yr transition period to organic certification influences soil quality and the weed seedbank. We studied two cropping systems during the transition period and the first certified organic season. A 4-yr rotation of corn, soybean, wheat/alfalfa, corn (C-S-W/A-C) [Zea mays L., Glycine max (L.) Merr., Triticum aestivum L., Medicago sativa L.], produced under a more complex management that included manure and cover crop residue, was compared to a perennial based corn, alfalfa, alfalfa, corn (C-A-A-C) rotation. We compared soil aggregate size distribution and bulk density after Year 1 and on completion of the transition period. Weed seedbank populations were quantified through two seasons in the greenhouse. Weed surface density and aboveground weed biomass were quantified in the field. Over the course of the study, the percentage of large soil macroaggregates (>2000 ?m size class) had 2.7 and 3.4-fold increase for the C-A-A-C and C-S-W/A-C treatments, respectively. The C-S-W/A-C system generated a 4.5-fold increase in aggregates of this class when wheat that was interseeded with alfalfa was harvested as forage. Bulk density decreased 14 and 6% for the C-S-W/A-C and the C-A-A-C systems, respectively. There was a 60 to nearly 300% increase in total weed seeds germinated in the greenhouse for the C-S-W/A-C system. This same system had a 60 to more than 500% decreased weed seedbank density in the field. We conclude from this study that either strategy can improve soil quality while the weed seedbank was better managed in the more complicated C-S-W/A-C system.

Corbin AndrewT; Thelen KurtD; Robertson GP; Leep RichardH

2010-11-01

228

[Functional state of the hemostatic system in the early periods after artificial heart implantation in calves  

UK PubMed Central (United Kingdom)

The functional state of hemostasis in the early periods after implantation of an artificial heart was studied in experiments on calves. The importance of studying the initial indices of the hemostasis system in calves both for selection of the animals and for determination of the tactics of conducting the experiment was shown. Preliminary drug management of the animals for the purpose of creating optimum functional correction of the coagulation and anticoagulation systems may have a marked positive effect. Further study of the state of hemostasis in all stages of the experiment will disclose the mechanisms of the regulation of this process under conditions of artificial heart implantation in calves.

Kudriashov BA; Shtengol'd ESh; Kovaleva TN; Liapina LA; Krylova AI

1981-04-01

229

Histophysiology of immune system and barrier organs in the late period of orchiectomy in Wistar rats.  

UK PubMed Central (United Kingdom)

We studied the histological and physiological changes in the organs of the immune system, liver, and lungs as well as colon microflora in the late period after orchiectomy in Wistar rats. It was shown that on day 52 after surgical castration leading to a sharp decline in androgens, activation of the immune system was detected with enhanced production of IL-12 and IL-6 and accumulation of neutrophils in the interalveolar septa of the lungs. The level of aspartate aminotransferase was within the normal range. Qualitative and quantitative changes of microflora were associated with increased number of opportunistic bacteria.

Kosyreva AM

2013-02-01

230

Periodic Density Modulation Effects on a Correlated two-dimensional Composite Fermion System  

CERN Document Server

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.

Sakhi, S

2001-01-01

231

Hysteresis effect in the ?=1 quantum Hall system under periodic electrostatic modulation  

International Nuclear Information System (INIS)

[en] The effect of a one-dimensional periodic electrostatic modulation on quantum Hall systems with filling factor ?=1, is studied. We propose that, either when the amplitude of the modulation potential or the tilt angle of the magnetic field is varied, the system can undergo a first-order phase transition from a fully spin-polarized homogeneous state to a partially spin-polarized charge-density-wave state, and show hysteresis behavior of the spin polarization. This is confirmed by our self-consistent numerical calculations within the Hartree-Fock approximation

2001-08-15

232

Inventory of thermal solar energy systems in the Netherlands: Period 1975-1992  

International Nuclear Information System (INIS)

[en] 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

1993-01-01

233

Global well-posedness of NLS-KdV systems for periodic functions  

Directory of Open Access Journals (Sweden)

Full Text Available We prove that the Cauchy problem of the Schrodinger-Korteweg-deVries (NLS-KdV) system for periodic functions is globally well-posed for initial data in the energy space $H^1imes H^1$. More precisely, we show that the non-resonant NLS-KdV system is globally well-posed for initial data in $H^s(mathbb{T})imes H^s(mathbb{T})$ with $s>11/13$ and the resonant NLS-KdV system is globally well-posed with $s>8/9$. The strategy is to apply the I-method used by Colliander, Keel, Staffilani, Takaoka and Tao. By doing this, we improve the results by Arbieto, Corcho and Matheus concerning the global well-posedness of NLS-KdV systems.

Carlos Matheus

2007-01-01

234

CRYSCOR: a program for the post-Hartree-Fock treatment of periodic systems.  

Science.gov (United States)

Cryscor is a periodic post-Hartree-Fock program based on local functions in direct space, i.e., Wannier functions and projected atomic orbitals. It uses atom centered Gaussians as basis functions. The Hartree-Fock reference, as well as symmetry information, is provided by the Crystal program. Cryscor presently features an efficient and parallel implementation of periodic local second order Møller-Plesset perturbation theory (MP2), which allows us to study 1D-, 2D- and 3D-periodic systems beyond 1000 basis functions per unit cell. Apart from the correlation energy also the MP2 density matrix, and from that the Compton profile, are available. Very recently, a new module for calculating excitonic band gaps at the uncorrelated Configuration-Interaction-Singles (CIS) level has been added. Other advancements include new extrapolation techniques for calculating surface adsorption on semi-infinite solids. In this paper the diverse features and recent advances of the present Cryscor version are illustrated by exemplary applications to various systems: the adsorption of an argon monolayer on the MgO (100) surface, the rolling energy of a boron nitride nanoscroll, the relative stability of different aluminosilicates, the inclusion energy of methane in methane-ice-clathrates, and the effect of electron correlation on charge and momentum density of ?-quartz. Furthermore, we present some first tentative CIS results for excitonic band gaps of simple 3D-crystals, and their dependence on the diffuseness of the basis set. PMID:22334044

Pisani, Cesare; Schütz, Martin; Casassa, Silvia; Usvyat, Denis; Maschio, Lorenzo; Lorenz, Marco; Erba, Alessandro

2012-02-15

235

CRYSCOR: a program for the post-Hartree-Fock treatment of periodic systems.  

UK PubMed Central (United Kingdom)

Cryscor is a periodic post-Hartree-Fock program based on local functions in direct space, i.e., Wannier functions and projected atomic orbitals. It uses atom centered Gaussians as basis functions. The Hartree-Fock reference, as well as symmetry information, is provided by the Crystal program. Cryscor presently features an efficient and parallel implementation of periodic local second order Møller-Plesset perturbation theory (MP2), which allows us to study 1D-, 2D- and 3D-periodic systems beyond 1000 basis functions per unit cell. Apart from the correlation energy also the MP2 density matrix, and from that the Compton profile, are available. Very recently, a new module for calculating excitonic band gaps at the uncorrelated Configuration-Interaction-Singles (CIS) level has been added. Other advancements include new extrapolation techniques for calculating surface adsorption on semi-infinite solids. In this paper the diverse features and recent advances of the present Cryscor version are illustrated by exemplary applications to various systems: the adsorption of an argon monolayer on the MgO (100) surface, the rolling energy of a boron nitride nanoscroll, the relative stability of different aluminosilicates, the inclusion energy of methane in methane-ice-clathrates, and the effect of electron correlation on charge and momentum density of ?-quartz. Furthermore, we present some first tentative CIS results for excitonic band gaps of simple 3D-crystals, and their dependence on the diffuseness of the basis set.

Pisani C; Schütz M; Casassa S; Usvyat D; Maschio L; Lorenz M; Erba A

2012-06-01

236

Self-isospectral tri-supersymmetry in PT-symmetric quantum systems with pure imaginary periodicity  

International Nuclear Information System (INIS)

[en] 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.

2012-01-01

237

A new Lax-Oleinik type semigroup for time-periodic positive definite Lagrangian systems  

CERN Document Server

In this paper we introduce a new Lax-Oleinik type semigroup associated with positive definite Lagrangian systems for both the time-independent case and the time-periodic case. We show that the new Lax-Oleinik type semigroup can take the place of the Lax-Oleinik semigroup in the weak KAM theory. More than that, the new Lax-Oleinik type semigroup converges to a backward weak KAM solution faster than the Lax-Oleinik semigroup in the time-independent case, and the new Lax-Oleinik type semigroup converges to a backward weak KAM solution in the time-periodic case, while it is shown by Fathi and Mather that there is no such convergence of the Lax-Oleinik semigroup.

Wang, Kaizhi

2010-01-01

238

Extremely long period-stacking structure in the Sb-Te binary system.  

UK PubMed Central (United Kingdom)

The crystal structure of the delta-phase in the Sb-Te binary system has been determined by synchrotron powder diffraction. It is clearly shown that many intermetallic compounds, which have different stacking periods depending on compound composition, exist in this phase. These structures are based on the cubic ABC stacking structure, and two kinds of fundamental structural units form an intergrowth along the stacking direction at the atomic level. The chemical formulae of these compounds are expressed as Sb(2n)Te3, where n is an integer and the number of stacking layers is 2n + 3. There is a relationship of inverse proportionality between the stacking period and the Te concentration.

Kifune K; Kubota Y; Matsunaga T; Yamada N

2005-10-01

239

Fast and spectrally accurate Ewald summation for 2-periodic electrostatic systems  

CERN Multimedia

A new method for Ewald summation in planar/slablike geometry, i.e. systems where periodicity applies in two dimensions and the last dimension is "free" (2P), is presented. We employ a spectral representation in terms of both Fourier series and integrals. This allows us to concisely derive both the 2P Ewald sum and a fast PME-type method suitable for large-scale computations. The primary results are: (i) close and illuminating connections between the 2P problem and the standard Ewald sum and associated fast methods for full periodicity; (ii) a fast, O(N log N), and spectrally accurate PME-type method for the 2P k-space Ewald sum that uses vastly less memory than traditional PME methods; (iii) errors that decouple, such that parameter selection is simplified. We give analytical and numerical results to support this.

Lindbo, Dag

2011-01-01

240

Fast and spectrally accurate Ewald summation for 2-periodic electrostatic systems  

Science.gov (United States)

A new method for Ewald summation in planar/slablike geometry, i.e., systems where periodicity applies in two dimensions and the last dimension is ``free'' (2P), is presented. We employ a spectral representation in terms of both Fourier series and integrals. This allows us to concisely derive both the 2P Ewald sum and a fast particle mesh Ewald (PME)-type method suitable for large-scale computations. The primary results are: (i) close and illuminating connections between the 2P problem and the standard Ewald sum and associated fast methods for full periodicity; (ii) a fast, O(N log N), and spectrally accurate PME-type method for the 2P k-space Ewald sum that uses vastly less memory than traditional PME methods; (iii) errors that decouple, such that parameter selection is simplified. We give analytical and numerical results to support this.

Lindbo, Dag; Tornberg, Anna-Karin

2012-04-01

 
 
 
 
241

The existence of periodic solutions of the n-species Lotka-Volterra competition systems with impulsive  

Energy Technology Data Exchange (ETDEWEB)

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.

Jin Zhen E-mail: jinzhn@263.net; Ma Zhien; Maoan Han

2004-10-01

242

The existence of periodic solutions of the n-species Lotka-Volterra competition systems with impulsive  

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.

2004-01-01

243

Pseudo almost periodic solutions to some systems of nonlinear hyperbolic second-order partial differential equations  

Science.gov (United States)

In this Dissertation, the existence of pseudo almost periodic solutions to some systems of nonlinear hyperbolic second-order partial differential equations is established. For that, (Al-Islam [4]) is first studied and then obtained under some suitable assumptions. That is, the existence of pseudo almost periodic solutions to a hyperbolic second-order partial differential equation with delay. The second-order partial differential equation (1) represents a mathematical model for the dynamics of gas absorption, given by uxt+a x,tux=Cx,t,u x,t , u0,t=4 t, 1 where a : [0, L] x RR , C : [0, L] x R x RR , and ? : RR are (jointly) continuous functions ( t being the greatest integer function) and L > 0. The results in this Dissertation generalize those of Poorkarimi and Wiener [22]. Secondly, a generalization of the above-mentioned system consisting of the non-linear hyperbolic second-order partial differential equation uxt+a x,tux+bx,t ut+cx,tu=f x,t,u, x? 0,L,t? R, 2 equipped with the boundary conditions ux,0 =40x, u0,t=u 0t, uxx,0=y 0x, x?0,L, t?R, 3 where a, b, c : [0, L ] x RR and f : [0, L] x R x RR are (jointly) continuous functions is studied. Under some suitable assumptions, the existence and uniqueness of pseudo almost periodic solutions to particular cases, as well as the general case of the second-order hyperbolic partial differential equation (2) are studied. The results of all studies contained within this text extend those obtained by Aziz and Meyers [6] in the periodic setting.

Al-Islam, Najja Shakir

244

Quantum Intermittency in Almost-Periodic Lattice Systems Derived from their Spectral Properties  

CERN Multimedia

Hamiltonian tridiagonal matrices characterized by multi-fractal spectral measures in the family of Iterated Function Systems can be constructed by a recursive technique here described. We prove that these Hamiltonians are almost-periodic. They are suited to describe quantum lattice systems with nearest neighbours coupling, as well as chains of linear classical oscillators, and electrical transmission lines. We investigate numerically and theoretically the time dynamics of the systems so constructed. We derive a relation linking the long-time, power-law behaviour of the moments of the position operator, expressed by a scaling function $\\beta$ of the moment order $\\alpha$, and spectral multi-fractal dimensions, D_q, via $\\beta(\\alpha) = D_{1-\\alpha}$. We show cases in which this relation is exact, and cases where it is only approximate, unveiling the reasons for the discrepancies.

Mantica, G

1996-01-01

245

Resonance tongues and patterns in periodically forced reaction-diffusion systems  

CERN Multimedia

Various resonant and near-resonant patterns form in a light-sensitive Belousov-Zhabotinsky (BZ) reaction in response to a spatially-homogeneous time-periodic perturbation with light. The regions (tongues) in the forcing frequency and forcing amplitude parameter plane where resonant patterns form are identified through analysis of the temporal response of the patterns. Resonant and near-resonant responses are distinguished. The unforced BZ reaction shows both spatially-uniform oscillations and rotating spiral waves, while the forced system shows patterns such as standing-wave labyrinths and rotating spiral waves. The patterns depend on the amplitude and frequency of the perturbation, and also on whether the system responds to the forcing near the uniform oscillation frequency or the spiral wave frequency. Numerical simulations of a forced FitzHugh-Nagumo reaction-diffusion model show both resonant and near-resonant patterns similar to the BZ chemical system.

Lin, A L; Meron, E; Swinney, H L; Lin, Anna L.; Hagberg, Aric; Meron, Ehud; Swinney, Harry L.

2004-01-01

246

Enhancing functionality and performance in the PVM network computing system. Period 1 progress report  

Energy Technology Data Exchange (ETDEWEB)

The research funded by this grant is part of an ongoing research project in heterogeneous distributed computing with the PVM system, at Emory as well as at Oak Ridge Labs and the University of Tennessee. This grant primarily supports research at Emory that continues to evolve new concepts and systems in distributed computing, but it also includes the PI`s ongoing interaction with the other groups in terms of collaborative research as well as software systems development and maintenance. The research effort at Emory has, in this first project period of the renewal (September 1994-June 1995), focused on (a) I/O frameworks for supporting data management in PVM; (b) evolution of a multithreaded concurrent computing model; and (c) responsive and portable graphical profiling tools for PVM.

Sunderam, V.

1995-08-01

247

Anharmonic vibrational properties in periodic systems: energy, electron-phonon coupling, and stress  

Science.gov (United States)

A unified approach is used to study vibrational properties of periodic systems with first-principles methods and including anharmonic effects. Our approach provides a theoretical basis for the determination of phonon-dependent quantities at finite temperatures. The low-energy portion of the Born-Oppenheimer energy surface is mapped and used to calculate the total vibrational energy including anharmonic effects, electron-phonon coupling, and the vibrational contribution to the stress tensor. We report results for the temperature dependence of the electronic band gap and the linear coefficient of thermal expansion of diamond, lithium hydride, and lithium deuteride.

Monserrat, Bartomeu; Drummond, N. D.; Needs, R. J.

2013-04-01

248

Analysis of physicochemical properties of elements of the third group of Mendeleyev's Periodic System  

International Nuclear Information System (INIS)

[en] Genetic relations of the values of physical and chemical properties of the elements in the 3d group of Mendeleyev's Periodic Systems, in clouding boron, indium, scandium, yttrium, lanthanum, actinium and other elements, are studied. Proposed are the differential equations enabling the establishment of relationships between the values of fundamental properties (atomic number, relative density, molecular/atomic mass, atomic radius) and derived properties (heat capacity, entropy, melting and boiling temperatures, melting and evaporation enthalpies). These equations can be used both for identification of substances and forecasting the values of properties of the above elements and their compounds

1991-01-01

249

Quantization and Fractional Quantization of Currents in Periodically Driven Stochastic Systems I: Average Currents  

CERN Multimedia

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.

Chernyak, Vladimir Y; Sinitsyn, Nikolai A

2011-01-01

250

Buying Time—The Immune System Determinants of the Incubation Period to Respiratory Viruses  

Directory of Open Access Journals (Sweden)

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.

Tamar Hermesh; Bruno Moltedo; Carolina B. López; Thomas M. Moran

2010-01-01

251

Quasi-periodic propagation in time of some classical/quantum systems: Nielsen's conserved quantity and Floquet properties  

International Nuclear Information System (INIS)

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.

2009-01-01

252

Nonlinear stability of periodic traveling wave solutions of systems of viscous conservation laws in the generic case  

CERN Document Server

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.

Johnson, Mat

2010-01-01

253

Non-linear second-order periodic systems with non-smooth potential  

CERN Multimedia

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.

Papageorgiou, E H; Papageorgiou, Evgenia H; Papageorgiou, Nikolaos S

2005-01-01

254

An efficient algorithm for translationally invariant finite-size periodic lattice systems in one spatial dimension  

International Nuclear Information System (INIS)

We develop an efficient algorithm to find a matrix product state representation of the ground-state wavefunctions for translationally invariant finite-size periodic lattice systems in one spatial dimension. This is based on the observation that the efficient computation of the ground-state energy per site only needs to retain a certain number of the largest eigenvalues of the transfer matrix for a matrix product state, without any sacrifice of accuracy. The computational cost is independent of the system's size, and scales as ?3 with ? being the truncation dimension. The algorithm is tested for the critical quantum Ising model in a transverse field on a finite-size lattice, with the size as large as 4800 for the truncation dimension 200. (fast track communication)

2009-07-10

255

An efficient algorithm for translationally invariant finite-size periodic lattice systems in one spatial dimension  

Energy Technology Data Exchange (ETDEWEB)

We develop an efficient algorithm to find a matrix product state representation of the ground-state wavefunctions for translationally invariant finite-size periodic lattice systems in one spatial dimension. This is based on the observation that the efficient computation of the ground-state energy per site only needs to retain a certain number of the largest eigenvalues of the transfer matrix for a matrix product state, without any sacrifice of accuracy. The computational cost is independent of the system's size, and scales as {chi}{sup 3} with {chi} being the truncation dimension. The algorithm is tested for the critical quantum Ising model in a transverse field on a finite-size lattice, with the size as large as 4800 for the truncation dimension 200. (fast track communication)

Shi Qianqian; Zhou Huanqiang [Centre for Modern Physics and Department of Physics, Chongqing University, Chongqing 400044 (China)

2009-07-10

256

Light and colour curve observations and analysis of the short period eclipsing binary system UV Psc  

International Nuclear Information System (INIS)

The author has presented and analysed B and V light curves and the (B - V)-colour curve of the short period (RS CVn type) binary system UV Psc, and derived absolute information from the available data. Chi2 minimization procedures were utilized to a large extent in fitting light and colour curves. The solutions show the binary to be at a distance of about 90 pc with two detached components which are close to the main sequence (G2 and K0). The inclination of the orbit is close to 900. Photometric irregularities present in the light curve are briefly considered in relation to current ideas on RS CVn systems, and the colour information indicates a locally hotter (rather than cooler) region is responsible for the irregularities. (Auth.)

1979-01-01

257

Dynamical systems analysis of fluid transport in time-periodic vortex ring flows  

Science.gov (United States)

It is known that the stable and unstable manifolds of dynamical systems theory provide a powerful tool for understanding Lagrangian aspects of time-periodic flows. In this work we consider two time-periodic vortex ring flows. The first is a vortex ring with an elliptical core. The manifolds provide information about entrainment and detrainment of irrotational fluid into and out of the volume transported with the ring. The likeness of the manifolds with features observed in flow visualization experiments of turbulent vortex rings suggests that a similar process might be at play. However, what precise modes of unsteadiness are responsible for stirring in a turbulent vortex ring is left as an open question. The second situation is that of two leapfrogging rings. The unstable manifold shows striking agreement with even the fine features of smoke visualization photographs, suggesting that fluid elements in the vicinity of the manifold are drawn out along it and begin to reveal its structure. We suggest that interpretations of these photographs that argue for complex vorticity dynamics ought to be reconsidered. Recently, theoretical and computational tools have been developed to locate structures analogous to stable and unstable manifolds in aperiodic, or finite-time systems. The usefulness of these analogs is demonstrated, using vortex ring flows as an example, in the paper by Shadden, Dabiri, and Marsden [Phys. Fluids 18, 047105 (2006)].

Shariff, Karim; Leonard, Anthony; Ferziger, Joel H.

2006-04-01

258

Systemic and pulmonary screening of patients with Behcet's disease during periodic follow-up.  

UK PubMed Central (United Kingdom)

Behçet's disease (BD) is a multisystemic disease that may involve all systems, the most common symptoms being oral and genital ulcerations and ocular involvement. Pulmonary involvement is not usually investigated in BD unless there is a specific complaint. In this study, pulmonary parameters and findings were investigated in BD patients at periodic follow-ups. A total of 112 subjects with a definitive diagnosis of BD from the Ocular Diseases Polyclinic, Behçet Disease Center, Ankara Training and Research Hospital and who had been referred to the Thoracic Diseases Polyclinic between January-October 2010 were evaluated. In the patients, the absence of active smoking, pregnancy, lactation and systemic steroid use were especially considered. A total of 112 patients between 14 and 61 years-old (53 male, 59 female) were enrolled in the study. The duration of follow-up varied between 1 and 22 years. The most commonly encountered symptom was hemoptysis observed in 18 subjects. 43 patients had mild obstruction, 9 patients had moderate obstruction, 4 patients had advanced obstruction and 4 patients showed restrictive alterations. Thoracic CT was normal for 83 subjects. Pulmonary involvement was observed as a pulmonary artery aneurysm in 4 patients and was treated. In BD, although anyone of PFT and CT values is normal, others may show pathological values. We believe that it would be useful in the follow-up to keep a regular record of the patient data and to perform PFT and, if possible, CT periodically.

Bilgin G; Sungur G; Kucukterzi V

2013-03-01

259

Systemic and pulmonary screening of patients with Behçet's disease during periodic follow-up.  

Science.gov (United States)

Behçet's disease (BD) is a multisystemic disease that may involve all systems, the most common symptoms being oral and genital ulcerations and ocular involvement. Pulmonary involvement is not usually investigated in BD unless there is a specific complaint. In this study, pulmonary parameters and findings were investigated in BD patients at periodic follow-ups. A total of 112 subjects with a definitive diagnosis of BD from the Ocular Diseases Polyclinic, Behçet Disease Center, Ankara Training and Research Hospital and who had been referred to the Thoracic Diseases Polyclinic between January-October 2010 were evaluated. In the patients, the absence of active smoking, pregnancy, lactation and systemic steroid use were especially considered. A total of 112 patients between 14 and 61 years-old (53 male, 59 female) were enrolled in the study. The duration of follow-up varied between 1 and 22 years. The most commonly encountered symptom was hemoptysis observed in 18 subjects. 43 patients had mild obstruction, 9 patients had moderate obstruction, 4 patients had advanced obstruction and 4 patients showed restrictive alterations. Thoracic CT was normal for 83 subjects. Pulmonary involvement was observed as a pulmonary artery aneurysm in 4 patients and was treated. In BD, although anyone of PFT and CT values is normal, others may show pathological values. We believe that it would be useful in the follow-up to keep a regular record of the patient data and to perform PFT and, if possible, CT periodically. PMID:23266040

Bilgin, Gulden; Sungur, Gulten; Kucukterzi, Vildan

2012-12-21

260

Optimization of Water Circulation Period for the Culture of Goldfish with Spinach in Aquaponic System  

Directory of Open Access Journals (Sweden)

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.

A. P. Shete; A. K. Verma; R. S. Tandel; Chandra Prakash; V. K. Tiwari; Tanveer Hussain

2013-01-01

 
 
 
 
261

Inventory of thermal solar energy systems in the Netherlands: Period 1975-1992; Inventarisatie thermische zonne-energiesystemen in Nederland: Periode 1975-1992  

Energy Technology Data Exchange (ETDEWEB)

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

Warmerdam, J.M.; Stap, C.A.M.

1993-10-01

262

Optimal dispatching in a periodically review in on-line manufacturing system with vendors evaluation  

Directory of Open Access Journals (Sweden)

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.

Dipak Ranjan Jana; K. V. Santha Kumari; B. K. Singh

2011-01-01

263

Mean values of up time and down time of periodically tested redundant systems with exponential life distribution of sub systems  

International Nuclear Information System (INIS)

[en] Whereever non self-reporting faults have to be considered, (periodic) tests belong to the more important measures of reliability assurance. Although a general theory is still missing, the desired statements on mean time between failures and mean down time can be made for the important special case of exponential distribution of system's life. As examples the 1-out of-2- and the 2-out of-3-systems are treated extensively. (orig.)[de] Ueberall dort, wo Fehler beachtet werden muessen, die sich nicht selbst melden, gehoert die (periodische) Ueberpruefung zu den wichtigsten Massnahmen der Zuverlaessigkeitssicherung. Wenn auch die allgemeine Theorie noch fehlt, so koennen doch im wichtigen Spezialfall der exponentialverteilten Lebensdauer der Teilsysteme die gewuenschten Angaben ueber mittlere fehlerfreie Betriebsdauer und mittlere Ausfalldauer und damit ueber die mittlere Gefahrenhaeufigkeit gemacht werden. Als Beispiel werden das 1-von-2- und das 2-von-3-System ausfuehrlich behandelt. (orig.)

1977-01-01

264

Multi-period steam turbine network optimisation. Part II: Development of a multi-period MINLP model of a utility system  

Energy Technology Data Exchange (ETDEWEB)

Efficient utility systems are important both due to the impact utility systems have on the economic efficiency of the process industry, as well as the negative environmental effects of energy conversion. In this paper a methodology is used to build a multi-period MINLP model for steam turbine network of a utility system. The methodology consists of several steps, including the building of a simulation model of the system, the development of regression model(s) of the system based on simulation and D-optimal design, and finally the development of a MINLP model. The results show that the methodology is capable of analysing a relatively complex steam turbine network in a utility system. The systematic methodology can help to make the MINLP model compact and transparent, and thus avoid the major challenges that are connected with solving large (nonconvex) MINLP models. However, the MINLP models developed using the methodology should be regarded as 'ad hoc' models, and have certain limitations as the models are not so flexible compared to models where all the units in the utility system are modelled in detail. (author)

Tveit, Tor-Martin; Fogelholm, Carl-Johan [Helsinki University of Technology, Energy Engineering and Environmental Protection, P.O. Box 4400, FIN-02015 HUT (Finland)

2006-10-15

265

The periodical property of the transmission in a prefilter quadrupole system  

International Nuclear Information System (INIS)

A computer simulation program has been constructed to model the motion of ions in the field of quadrupole mass analyzers. It has been successfully used to calculate the resolution and transmission of the QMS as well as to optimize the length of the prefilter coupled to the analyzer. The program can calculate the average maximum displacement of ions from the axis of the quadrupole rod system. The average maximum displacement function (Dr) well characterizes the transmission of quadrupole mass filter: the higher the displacement is the smaller the probability of free ion transmission of a QMS with prefilter is a periodic function of the length of the prefilter. This behavior was experimentally proved for He ions earlier and experiments have been extended to higher masses in these measurement. The periodic nature of the transmission of quadrupole MS with prefilter as a function of prefilter length has been experimentally proved, without the influence of fringing fields at the entrance to the analyzer, in the mass range of 12-260 Da. (K.A.) 4 refs.; 3 figs.

1995-01-01

266

Coherent states of the driven Rydberg atom: Quantum-classical correspondence of periodically driven systems  

International Nuclear Information System (INIS)

A methodology to calculate generalized coherent states for a periodically driven system is presented. We study wave packets constructed as a linear combination of suitable Floquet states of the three-dimensional Rydberg atom in a microwave field. The driven coherent states show classical space localization, spreading, and revivals and remain localized along the classical trajectory. The microwave strength and frequency have a great effect in the localization of Floquet states, since quasienergy avoided crossings produce delocalization of the Floquet states, showing that tuning of the parameters is very important. Using wavelet-based time-frequency analysis, the classical phase-space structure is determined, which allows us to show that the driven coherent state is located in a large regular region in which the z coordinate is in resonance with the external field. The expectation values of the wave packet show that the driven coherent state evolves along the classical trajectory.

2005-01-01

267

Orbital-unrelaxed Lagrangian density matrices for periodic systems at the local MP2 level  

International Nuclear Information System (INIS)

In the present paper a method based on the Hylleraas functional is proposed in order to obtain correlated ground state density matrices for periodic systems at the level of local MP2. The general properties of these density matrices, namely size-extensivity, translational invariance, exponential decay of the off-diagonal elements, etc are discussed. As test examples we investigate the influence of the electron correlation on the density in diamond and strontium titanate (in the latter case via the Mulliken charges). The calculations reveal that in diamond the concentration of the electrons in the bond region decreases when the correlation is taken into account, but the change in the density relative to Hartree-Fock is small. In the case of SrTiO3, this change is more significant and causes a lowering of the ionicity of this crystal.

2008-06-01

268

System of Model Functions for the Two-Dimensional Periodic Magnetic Schrödinger Operator.  

UK PubMed Central (United Kingdom)

For the periodic magnetic Schrodinger operator in two dimensions wedescribe a set of model functions, which solve the equations for eigenfunctions approximately. There exist the model functions of two types: a weak diffraction typeand a strong diffraction type. It is shown that the model functions are mutually"almost orthogonal" and the model set is complete in the high energy region -- alleigenfunctions with eigenvalues large enough can be described in terms of the modelfunctions. The present paper contains the construction of the system. This is thefirst of two papers designed to prove that in the high energy region each eigenfunctionis close to exactly one of the model functions for a rich set of quasimomenta, forthe rest of quasimomenta it is close to a linear combination of the model functions.

Yu. E. Karpeshina

269

The optimal P3M algorithm for computing electrostatic energies in periodic systems  

CERN Document Server

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).

Ballenegger, V; Holm, Ch; Lenz, O

2007-01-01

270

Optimal Backup Interval for a Database System with Full and Periodic Incremental Backup  

Directory of Open Access Journals (Sweden)

Full Text Available This paper considers the following backup scheme for a database system: a database is updated at a nonhomogeneous Poisson process and an amount of updated files accumulates additively. To ensure the safety of data, full backup are performed at time NT=L or when the database fails, whichever occurs first, and between them, incremental backups are made at periodic times iT (i=1, 2, …, N-1) so as to make the backup efficiently. Using the theory of cumulative processes, the expected cost is obtained, and optimal numbers N* of incremental backup which minimizes it are analytically discussed when incremental backup interval T or full backup interval L is given. Finally, it is shown as examples that optimal numbers are numerically computed.

Cunhua Qian; Yingyan Huang; Xufeng Zhao; Toshio Nakagawa

2010-01-01

271

The endocannabinoid system in critical neurodevelopmental periods: sex differences and neuropsychiatric implications.  

UK PubMed Central (United Kingdom)

This review focuses on the endocannabinoid system as a crucial player during critical periods of brain development, and how its disturbance either by early life stressful events or cannabis consumption may lead to important neuropsychiatric signs and symptoms. First we discuss the advantages and limitations of animal models within the framework of neuropsychiatric research and the crucial role of genetic and environmental factors for the establishment of vulnerable phenotypes. We are becoming aware of important sex differences that have emerged in relation to the psychobiology of cannabinoids. We will discuss sexual dimorphisms observed within the endogenous cannabinoid system, as well as those observed with exogenously administered cannabinoids. We start with how the expression of cannabinoid CB(1) receptors is regulated throughout development. Then, we discuss recent results showing how an experimental model of early maternal deprivation, which induces long-term neuropsychiatric symptoms, interacts in a sex-dependent manner with the brain endocannabinoid system during development. This is followed by a discussion of differential vulnerability to the pathological sequelae stemming from cannabinoid exposure during adolescence. Next we talk about sex differences in the interactions between cannabinoids and other drugs of abuse. Finally, we discuss the potential implications that organizational and activational actions of gonadal steroids may have in establishing and maintaining sex dependence in the neurobiological actions of cannabinoids and their interaction with stress.

Viveros MP; Llorente R; Suarez J; Llorente-Berzal A; López-Gallardo M; de Fonseca FR

2012-01-01

272

Large-Scale, Synoptic-Period Weather Systems in Mars' Atmosphere  

Science.gov (United States)

During late autumn through early spring, extratropical regions on Mars exhibit profound mean zonal equator-to-pole thermal contrasts associated with its waxing and waning seasonal polar ice caps. The imposition of this strong meridional temperature gradient supports intense eastward-traveling, synoptic-period weather systems (i.e., transient baroclinic/barotropic waves) within Mars' extratropical atmosphere. These disturbances grow, mature and decay within the east-west varying seasonal-mean middle and high-latitude westerly jet stream (i.e., the polar vortex) on the planet. Near the surface, such weather disturbances indicated distinctive, spiraling "comma"-shaped dust cloud structures of large scale, and scimitar-shaped dust fronts, indicative of processes associated with cyclo- and fronto-genesis. The weather systems are most intense during specific seasons on Mars, and in both hemispheres. The northern hemisphere (NH) disturbances appear to be significantly more vigorous than their counterparts in the southern hemisphere (SH). Further, the NH weather systems and accompanying frontal waves appear to have significant impacts on the transport of tracer fields (e.g., particularly dust and to some extent water species (vapor/ice) as well). Regarding dust, frontal waves appear to be key agents in the lifting, lofting, organization and transport of this atmospheric aerosol. A brief background and supporting observations of Mars' extratropical weather systems is presented. This is followed by various modeling studies (i.e., ranging from highly simplified, mechanistic and fully complex global circulation modeling investigations) that we are pursuing. In particular, transport of scalar quantities (e.g., tracers and high-order dynamically revealing diagnostic fields) are investigated. A discussion of outstanding issues and future modeling pursuits is offered related to Mars' extratropical traveling weather systems.

Hollingsworth, Jeffery L.; Kahre, M.

2013-10-01

273

Investigation of periodic systems by means of the generalized Hill method  

International Nuclear Information System (INIS)

[en] 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

1994-01-01

274

A magnetic reconnection model for quasi-periodic oscillations in black hole systems  

Science.gov (United States)

The quasi-periodic oscillations (QPOs) in black hole (BH) systems with different scales are interpreted based on the magnetic reconnection of large-scale magnetic fields generated by toroidal electric currents flowing in the inner region of the accretion disk, where the current density is assumed to be proportional to the mass density of the accreting plasma. The magnetic connection (MC) is taken into account in resolving dynamic equations describing the accretion disk, in which the MC between the inner and outer disk regions, between the plunging region and the disk, and between the BH horizon and the disk are involved. It turns out that a single QPO frequency associated with several BH systems with different scales can be fitted by invoking the magnetic reconnection due to the MC between the inner and outer regions of the disk, including the BH binaries XTE J1859+226, XTE J1650-500 and GRS 1915+105 and the massive BHs in NGC 5408 X-1 and RE J1034+396. In addition, the X-ray spectra corresponding to the QPOs for these sources are fitted based on the typical disk-corona model.

Huang, Chang-Yin; Wang, Ding-Xiong; Wang, Jiu-Zhou; Wang, Zhi-Yun

2013-06-01

275

Analysis of the ancient river system in Loulan period in Lop Nur region  

Science.gov (United States)

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.

Zhu, Jianfeng; Jia, Peng; Nie, Yueping

2010-09-01

276

Physical properties of the 0.94-day period transiting planetary system WASP-18  

CERN Multimedia

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 defocussing we achieve a photometric precision of 0.47 to 0.83 mmag per observation over complete transit events. The data are analysed 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 Mjup R_b = 1.165 +/- 0.055 +/- 0.014 Rjup (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 Mjup) have eccentric orbits, whereas significant orbital eccentricity has been detected for only four of the 46 less massive planet...

Southworth, John; Dominik, M; Glitrup, M; Jørgensen, U G; Liebig, C; Mathiasen, M; Anderson, D R; Bozza, V; Browne, P; Burgdorf, M; Novati, S Calchi; Dreizler, S; Finet, F; Harpsoe, K; Hessman, F; Hundertmark, M; Maier, G; Mancini, L; Maxted, P F L; Rahvar, S; Ricci, D; Scarpetta, G; Skottfelt, J; Snodgrass, C; Surdej, J; Zimmer, F

2009-01-01

277

Equipartition design method of a quasi-periodic focusing-accelerating coupled system  

International Nuclear Information System (INIS)

Intense-beam proton linac sets a very severe requirement on the control of beam loss and emittance growth. Beam physics theory demonstrates that coupling of the strong space charge effect between different freedoms with different temperature will surely increase the beam emittance in the way of beam coherent instability. Therefore it is necessary to design an intense beam accelerator in accordance with the equipartition principle. However, this design is too tedious to reach full equipartition because the real proton linac is a quasi-periodic coupling system. Thus, the authors made a few modifications to TRACE3-D, which is a popular code in beam dynamics, and added the equipartition design function to it. When the modified TRACE3-D is used together with the PARMILA code, it is easy to realize equipartition. The author will introduce the modification to TRACE3-D code, and then illustrate its application to the design of a DTL linac section, which shows the importance of equipartition design in the intense beam linac

2002-01-01

278

Equipartitioning design method of a quasi-periodical focusing-accelerating coupled system  

International Nuclear Information System (INIS)

High-current proton linac sets a very severe requirement on the control of beam loss and emittance growth. Beam physics theory demonstrates that driven by the beam coherent instability, beam emittance grows due to the coupling of the strong space charge effect when an intense beam has different temperatures between different degrees of freedom. Therefore it is necessary to design an intense beam accelerator in line with the equipartitioning principle. However, this design becomes too tedious to reach full equipartitioning because a real proton linac is, in fact, a quasi-periodic coupling system. Taking the advantage of the code TRACE3-D, the authors modified it and added equipartitioning design function to it. It becomes a useful tool to readily realise equipartitioning design with the assistance of PARMILA code. The modification to TRACE3-D code is introduced, and then illustrate its application to the design of a DTL linac section, which shows the importance of equipartitioning design in the intense beam linac

2002-01-01

279

Multi-Layered Ring Log-Periodic Antennas Array Design for GPS Systems  

Directory of Open Access Journals (Sweden)

Full Text Available 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° fashion. The purpose of different angular orientations of the patches is to generate two orthogonally polarized fields, while -3dB coupler is used to provide the required amplitude and phase delays for circular polarization generation. This uniquely formed array has the capability of generating excellent circular polarization. An association of the coupler with the antennas has been established.This work is completed using the moment’s method of Momentum software. Good performances of adaptation and polarization were obtained. The simulation results are then presented and discussed.

M. Abri; S.M. Bahloul; H. Abri Badaoui

2012-01-01

280

The Period-Luminosity Relation of RR Lyrae Stars in the SDSS Photometric System  

CERN Multimedia

We provide the first detailed study of the RR Lyrae period-luminosity (PL) relation in the ugriz bandpasses of the Sloan Digital Sky Survey (SDSS) filter system. We argue that tight, simple PL relations are not present in the SDSS filters, except for the redder bandpasses i and (especially) z. However, for all bandpasses, we show that, by incorporating terms involving a (fairly reddening-independent) "pseudo-color" C_0 = (u-g)_0 - (g-r)_0, tight (non-linear) relations do obtain. We provide theoretically calibrated such relations in the present paper, which should be useful to derive precise absolute magnitudes (hence distances) and intrinsic colors (hence reddening values) to even {\\em individual} field RR Lyrae stars. For applications to cases where photometry in all five passbands may not be available, we also provide simple (though less precise) average PL relations for the i and z bandpasses, which read as follows: M_z = 0.839 - 1.295 log P + 0.211 log Z, M_i = 0.908 - 1.035 log P + 0.220 log Z. Similarly...

Cáceres, C

2008-01-01

 
 
 
 
281

KIC 4544587: an eccentric, short-period binary system with ? Sct pulsations and tidally excited modes  

Science.gov (United States)

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 yr per cycle. The primary and secondary components of KIC 4544587 reside within the ? Scuti and ? Dor instability region of the Hertzsprung-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 Kitt Peak Northern Observatory (KPNO), the fundamental parameters of this important system have been determined, including the stellar masses, 1.98 ±0.07 and 1.60 ± 0.06 M?, and radii, 1.76 ± 0.03 and 1.42 ± 0.02 R?, 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 are orbital harmonics: a signature of tidal resonance. While the measured amplitude of these modes may be partially attributed to residual signal from binary model subtraction, we demonstrate through consideration of the folded light curve that these frequencies do in fact correspond to tidally excited pulsations. Furthermore, we present an echelle diagram of the pressure mode frequency region (modulo the orbital frequency) and demonstrate that the tides are also influencing the p modes. A first look at asteroseismology hints that the secondary component is responsible for the p modes, which is contrary to our expectation that the hotter star should pulsate in higher radial overtone, higher frequency p modes.

Hambleton, K. M.; Kurtz, D. W.; Prša, A.; Guzik, J. A.; Pavlovski, K.; Bloemen, S.; Southworth, J.; Conroy, K.; Littlefair, S. P.; Fuller, J.

2013-09-01

282

Sensitive periods for the functional specialization of the neural system for human face processing.  

UK PubMed Central (United Kingdom)

The aim of the study was to identify possible sensitive phases in the development of the processing system for human faces. We tested the neural processing of faces in 11 humans who had been blind from birth and had undergone cataract surgery between 2 mo and 14 y of age. Pictures of faces and houses, scrambled versions of these pictures, and pictures of butterflies were presented while event-related potentials were recorded. Participants had to respond to the pictures of butterflies (targets) only. All participants, even those who had been blind from birth for several years, were able to categorize the pictures and to detect the targets. In healthy controls and in a group of visually impaired individuals with a history of developmental or incomplete congenital cataracts, the well-known enhancement of the N170 (negative peak around 170 ms) event-related potential to faces emerged, but a face-sensitive response was not observed in humans with a history of congenital dense cataracts. By contrast, this group showed a similar N170 response to all visual stimuli, which was indistinguishable from the N170 response to faces in the controls. The face-sensitive N170 response has been associated with the structural encoding of faces. Therefore, these data provide evidence for the hypothesis that the functional differentiation of category-specific neural representations in humans, presumably involving the elaboration of inhibitory circuits, is dependent on experience and linked to a sensitive period. Such functional specialization of neural systems seems necessary to archive high processing proficiency.

Röder B; Ley P; Shenoy BH; Kekunnaya R; Bottari D

2013-09-01

283

An integrated multi?period planning of the production and transportation of multiple petroleum products in a single pipeline system  

Directory of Open Access Journals (Sweden)

Full Text Available A multiproduct pipeline provides an economic way to transport large volumes of refined petroleum products over long distances. In such a pipeline, different products are pumped back?to?back without any separation device between them. The sequence and lengths of such pumping runs must be carefully selected in order to meet market demands while minimizing pipeline operational costs and satisfying several constraints. The production planning and scheduling of the products at the refinery must also be synchronized with the transportation in order to avoid the usage of the system at some peak?hour time intervals. In this paper, we propose a multi?period mixed integer nonlinear programming (MINLP) model for an optimal planning and scheduling of the production and transportation of multiple petroleum products from a refinery plant connected to several depots through a single pipeline system. The objective of this work is to generalize the mixed integer linear programming (MILP) formulation proposed by Cafaro and Cerdá (2004, Computers and Chemical Engineering) where only a single planning period was considered and the production planning and scheduling was not part of the decision process. Numerical examples show how the use of a single period model for a given time period may lead to infeasible solutions when it is used for the upcoming periods. These examples also show how integrating production planning with the transportation and the use of a multi?period model may result in a cost saving compared to using a single?period model for each period, independently.

Alberto Herrán; Fantahun M. Defersha; Mingyuan Chen; Jesús M. de la Cruz

2011-01-01

284

Almost Periodic Solution of a Diffusive Mixed System with Time Delay and Type III Functional Response  

Directory of Open Access Journals (Sweden)

Full Text Available A delayed predator-prey model with diffusion and competition is proposed. Some sufficient conditions on uniform persistence of the model have been obtained. By applying Liapunov-Razumikhin technique, we will point out, under almost periodic circumstances, a set of sufficient conditions that assure the existence and uniqueness of the positive almost periodic solution which is globally asymptotically stable.

Qiong Liu

2008-01-01

285

Peakon, compacton and loop excitations with periodic behavior in KdV type models related to Schrodinger system  

Energy Technology Data Exchange (ETDEWEB)

In this Letter, the linear variable separation approach is successfully extended to (1+1)-dimensional Korteweg-de Vries (KdV) type models related to Schrodinger system. Some significant types of solitons such as compacton, peakon and loop solutions with periodic behavior are simultaneously derived from the (1+1)-dimensional soliton system by entrancing appropriate piecewise smooth functions and multivalued functions.

Zheng Chunlong [Department of Physics, Zhejiang Lishui University, Lishui 323000 (China) and Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072 (China)]. E-mail: zjclzheng@yahoo.com.cn; Chen Liqun [Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072 (China); Zhang Jiefang [Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072 (China); Institute of Nonlinear Physics, Zhejiang Normal University, Jinhua 321004 (China)

2005-06-13

286

Effect of Periodic Variation of Sol-air Temperature on the Performance of Integrated Solar Collector Storage System  

Directory of Open Access Journals (Sweden)

Full Text Available Parametric study is carried out in the present article to investigate the unsteady performance of solar energy gain and heat retention of two different integrated-collector-storage systems. The systems are the conventional rectangular-shaped storage tank and the modified tank shaped as rectangular cuboid with one semi -circular top. The two systems have the same absorber surface area and volume for water. The heat and fluid flow is assumed to be unsteady, two-dimensional, laminar and incompressible. The performances of the two systems are evaluated based on the maximum temperature in the system during daytime heating period and nighttime cooling period. For comprehensive study, 24 hours simulations for 3 cases with different wall boundary condition impose on the absorber plate are investigated. The simulation results show that the modified system has better heat retain than the conventional system. Periodic variations of both systems are investigated, and it is found that both systems show consistent results on different days. The modified system is able to store most of the thermal energy in the semi-circular top region with higher temperature than that of the conventional system.

Nawaf H. Saeid; Tan Jun Wong

2010-01-01

287

Searches for Periodic Neutrino Emission from Binary Systems with 22 and 40 Strings of IceCube  

Science.gov (United States)

In this paper, we present the results of searches for periodic neutrino emission from a catalog of binary systems. Such modulation, observed in the photon flux, would be caused by the geometry of these systems. In the analysis, the period is fixed by these photon observations, while the phase and duration of the neutrino emission are treated as free parameters to be fit with the data. If the emission occurs during ~20% or less of the total period, this analysis achieves better sensitivity than a time-integrated analysis. We use the IceCube data taken from 2007 May 31 to 2008 April 5 with its 22 string configuration and from 2008 April 5 to 2009 May 20 with its 40 string configuration. No evidence for neutrino emission is found, with the strongest excess occurring for Cygnus X-3 at 2.1? significance after accounting for trials. Neutrino flux upper limits for both periodic and time-integrated emission are provided.

Abbasi, 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.; 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.; Cruz Silva, A. H.; 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.; Haj Ismail, A.; 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.; Pérez de los Heros, C.; 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.; IceCube Collaboration

2012-04-01

288

Chemiluminescence determination of mezlocillin by the luminol-potassium periodate system  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese 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 (more) 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 variables 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 th (more) e 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.

Shi, Wen Bing; Yang, Ji Dong

2008-01-01

289

Local ab initio methods for calculating optical band gaps in periodic systems. I. Periodic density fitted local configuration interaction singles method for polymers.  

UK PubMed Central (United Kingdom)

We present a density fitted local configuration interaction singles (CIS) method for calculating optical band gaps in 1D-periodic systems. The method is based on the Davidson diagonalization procedure, carried out in the reciprocal space. The one-electron part of the matrix-vector products is also evaluated in the reciprocal space, where the diagonality of the Fock matrix can be exploited. The contraction of the CIS vectors with the two electron integrals is performed in the direct space in the basis of localized occupied (Wannier) and virtual (projected atomic) orbitals. The direct space approach allows to utilize the sparsity of the integrals due to the local representation and locality of the exciton. The density fitting approximation employed for the two electron integrals reduces the nominal scaling with unit cell size to O(N(4)). Test calculations on a series of prototypical systems demonstrate that the method in its present stage can be used to calculate the excitonic band gaps of polymers with up to a few dozens of atoms in the cell. The computational cost depends on the locality of the exciton, but even relatively delocalized excitons occurring in the polybiphenyl in the parallel orientation, can be routinely treated with this method.

Lorenz M; Usvyat D; Schütz M

2011-03-01

290

Permanence for a class of periodic time-dependent predator-prey system with dispersal in a patchy-environment  

International Nuclear Information System (INIS)

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.

2008-01-01

291

Volcanic rocks of the Mendeleev Ridge (Arctic Ocean) - evidences for existence of the large igneous provinces within Arctic region: on the data of the High Arctic Russian Expedition "Arctic-2012"  

Science.gov (United States)

During the complex geological-geophysical survey within August-October 2012 cruise of the Russian Expedition "Arctica-2012" on 9 sampling station (dredge, box-corer, drill-core) spaced on 450 km from the south to north alongside the Mendeleev Ridge were recovered more than 100 kg submarine volcanic rocks (which is represented about 10-15% of the total recovered bottom material), from calc-alkaline basalts, normal and subalkaline tholeites till andesite-dacites, typical lavas with glassy matrix and volcanic breccias, tuff-breccias and subvolcanic dolerites. We have studied 4 volcanic samples which are drill-cored (30-60 cm) of basement rocks at the depths of 2000-2500 m (79° and 83°N) or consolidate fragments of 30 kg weight collected at the steep escarpments with >45° slopes, three of them are tholeitic basalts (SiO2: 45.4-50.7, Al2O3: 13.7-21.7, MgO: 3.4-4.8, TiO2: 2.5-2.8, CaO: 4.7-11.4, Fe2O3: 5.9-14.4, Na2O: 2.9-3.8, K2O: 0.5-2.1 %), but the other one - is tuffobreccia with angular fragments of crystallized basalts and dolerites, and hydrated carbonatized (LOI up to 20%, ??2 - 35%) matrix. Isotopic and geochemical characteristics of the sample studied (low degree of REE fractionation: Cen/Ybn 1.6-2.2, moderate enrichment of HREE - 10-15×?1, low ratios of highly incompatible trace elements: Th/Ce = 0.03-0.04, Th/Nb = 0.14-0.16, Ce/Nb = 1.0-4.1) are very similar to those of high-Ti alkaline basalts of continental traps (CFB) connected with large mantle plume activities [Arndt et al., 1998; Hofmann, 1988] and close to the earlier discovered basalts from Chukcha borderland [Mukasa et al., 2009, 2012]. Measured Sr, Nd ? Pb isotope compositions of basalts vary from moderately enriched to moderately depleted compositions (143Nd/144Nd= 0.512706 - 0.512887, 87Sr/86Sr=0.704127-0.708580, 206Pb/204Pb=18.66-19.07, 207Pb/204Pb= 15.51-15.65, 208Pb/204Pb=38.42-39.20), reflecting different stages of secondary alterations, melt contamination by sedimentary material of host rocks and progressive magmas evolution during mixing of asthenospheric substances of the upwelling plume with the lithospheric component. Relatively high-radiogenic osmium isotope composition of the studied basalts (187Os/188Omeas=0.51525-1.07316) indicates the presence of significant share of the enriched lithospheric component in the source of basalt melts and the formation of this source at expense of relatively aged substances (model Re-Os ages from 600 to 1200 Ma). Age determination of the studied basalts effusions by argon-argon method is ongoing process but we have separated about 30 zircon grains mainly magmatic appearance (Th/U=0.6-2.0, long-prismatic grains without any visible signs of digestion and recrystallization, and overgrowths) from 4 samples and determined their U-Pb SHRIMP ages. Obtained age clusters indicate existence of old sialic basement underlying Mendeleev Ridge rocks (captured zircons with the ages of 2.7, 1.9, 1.6 and 0.8-1.2 Ga), which composition could be correlated with continental complexes of the Eurasia margins. At the same time, the finding of the volcanogenic zircons within the basalts with the ages of 127 and 260 Ma does not exclude the plausible existence on the studied territory of Polar Arctic of basalt effusions of two (or more) of igneous complexes corresponded with activities of mantle plumes - Cretaceous-Cenozoic (HALIP) and Triassic-Permian (resembling Siberian traps) ages

Sergeev, Sergey; Petrov, Oleg; Morozov, Andrey; Kremenetsky, Alexander; Gusev, Evgeny; Shevchenko, Sergey; Krymsky, Robert; Belyatsky, Boris; Antonov, Anton; Rodionov, Nikolay

2013-04-01

292

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)

1990-01-01

293

Detecting unstable periodic orbits in high-dimensional chaotic systems from time series: reconstruction meeting with adaptation.  

UK PubMed Central (United Kingdom)

Detecting unstable periodic orbits (UPOs) in chaotic systems based solely on time series is a fundamental but extremely challenging problem in nonlinear dynamics. Previous approaches were applicable but mostly for low-dimensional chaotic systems. We develop a framework, integrating approximation theory of neural networks and adaptive synchronization, to address the problem of time-series-based detection of UPOs in high-dimensional chaotic systems. An example of finding UPOs from the classic Mackey-Glass equation is presented.

Ma H; Lin W; Lai YC

2013-05-01

294

H2 OPTIMAL FILTERING FOR DISCRETE-TIME LINEAR STOCHASTIC SYSTEMS WITH PERIODIC COEFFICIENTS AND MARKOVIAN JUMPING  

Directory of Open Access Journals (Sweden)

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.

Vasile Dragan; Toader Morozan; Adrian Mihail Stoica

2013-01-01

295

Tunable wideband bandstop acoustic filter based on 2D multi-physical phenomena periodic systems  

CERN Document Server

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.

Romero-García, V; Garcia-Raffi, L M

2011-01-01

296

76 FR 12300 - Safety Management System for Certificated Airports; Extension of Comment Period  

Science.gov (United States)

...Council International--North America (ACI-NA) and the American Association of Airport...extend the comment period for a second time. ACI-NA and AAAE also requested the FAA provide...comment on the proposed rule. Specifically, ACI-NA made the following requests:...

2011-03-07

297

The systemic velocities of four long-period cataclysmic variable stars  

CERN Multimedia

Although a large number of orbital periods of cataclysmic variable stars (CVs) have been measured, comparison of period and luminosity distributions with evolutionary theory is affected by strong selection effects. A test has been discovered which is independent of these selection effects and is based upon the kinematics of CVs (Kolb & Stehle, 1996). If the standard models of evolution are correct then long-period (P_orb > 5 hrs) CVs should be typically less than 1.5 Gyr old, and their line-of-sight velocity dispersion ($\\sigma_\\gamma$) should be small. We present results from a pilot study which indicate that this postulate is indeed true. Four long-period dwarf novae (EM Cyg, V426 Oph, SS Cyg and AH Her) were observed over a complete orbit, in order that accurate radial velocities be obtained. We find values of -1.7, 5.4, 15.4 and 1.8 km/s with uncertainties of order 3 km/s, referred to the dynamical Local Standard of Rest (LSR), leading to a dispersion of ~ 8 km/s. Calculation of a 95 per cent confiden...

North, R C; Kolb, U; Dhillon, V S; Moran, C K J

2002-01-01

298

Relationship between different types of stability for linear almost periodic systems in Banach spaces  

Directory of Open Access Journals (Sweden)

Full Text Available For the linear equation $x'= A(t)x$ with recurrent (almost periodic) coefficients in an arbitrary Banach space, we prove that the asymptotic stability of the null solution and of all limit equations implies the uniform stability of the null solution.

David N. Cheban

1999-01-01

299

Periodic solutions of a discrete-time diffusive system governed by backward difference equations  

Directory of Open Access Journals (Sweden)

Full Text Available A discrete-time delayed diffusion model governed by backward difference equations is investigated. By using the coincidence degree and the related continuation theorem as well as some priori estimates, easily verifiable sufficient criteria are established for the existence of positive periodic solutions.

Binxiang Dai; Jiezhong Zou

2005-01-01

300

Proof of the existence of wave operators for the hyperbolic systems with a potential periodic in time  

International Nuclear Information System (INIS)

[en] We prove the existence of the scattering operator for the wave equation with a potential which is periodic in time and has compact support in space, in dimension greater than or equal to 3, provided the energy is uniformly bounded. The key result is the decay of the local energy. The RAGE theorem of Georgiev and Petkov implies weak decay and we get strong convergence by using the compactness of the local evolution operator, derived from a microlocal analysis of the propagation of singularities. In the case where the dimension is odd, the decay is exponential for initial data: i) with compact support and ii) included in a subspace of finite codimension. We give some sufficient conditions for the boundedness of the energy by studying the spectrum of the local evolution operator. We extend these results to first order hermitian systems with arbitrary multiplicity and with a periodic potential such as the Dirac system in a periodic electromagnetic field

1987-01-01

 
 
 
 
301

Resolution of First- and Second-Order Linear Differential Equations with Periodic Inputs by a Computer Algebra System  

Directory of Open Access Journals (Sweden)

Full Text Available In signal processing, a pulse means a rapid change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value. A square wave function may be viewed as a pulse that repeats its occurrence periodically but the return to the baseline value takes some time to happen. When these periodic functions act as inputs in dynamic systems, the standard tool commonly used to solve the associated initial value problem (IVP) is Laplace transform and its inverse. We show how a computer algebra system may also provide the solution of these IVP straight forwardly by adequately introducing the periodic input.

M. Legua; I. Morales; L. M. Sánchez Ruiz

2008-01-01

302

Radar Observations of Convective System Variability in Relationship to African Easterly Waves during the 2006 AMMA Special Observing Period  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A radar-based analysis of the structure, motion, and rainfall variability of westward-propagating squall-line mesoscale convective systems (SLMCSs) in Niamey, Niger, during the African Monsoon Multidisciplinary Activities (AMMA) 2006 special observing period is combined with an analysis of 700-mb (h...

Williams, Earle R.; Rickenbach, Thomas; Guy, Nick; Nieto Ferreira, Rosana

303

Pareto efficiency of the pay-as-you-go pension system in a three-period-OLG model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper considers an unfunded linear pension system when workers make labor decisions more often than once in their life. To capture this feature, a three-period-overlapping-generations model is employed. On the one hand, the paper analyzes whether or not a Pay-as-you-go pension scheme is intergen...

Wrede, Matthias

304

Historiography of an initial period of the 50 years creation in USSR the system of long range detection  

International Nuclear Information System (INIS)

The paper specifies historiography of creation initial period of Soviet System of the Long Range Detection on the basis of newly discovered archival materials and the new approaches to the known facts and documents, mainly, from the comparison of the Long Range Detection history in USA and USSR. (author)

2006-01-01

305

Multiple positive periodic solutions to a non-autonomous Lotka-Volterra predator-prey system with harvesting terms  

Directory of Open Access Journals (Sweden)

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.

Kaihong Zhao; Yongkun Li

2011-01-01

306

Output-only modal analysis of linear time-periodic systems with application to wind turbine simulation data  

DEFF Research Database (Denmark)

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.

Allen, Matthew S.; Sracic, Michael W.

2011-01-01

307

Log-periodic oscillations in the specific heat behaviour for self-similar Ising type spin systems  

International Nuclear Information System (INIS)

[en] The self-similar model of spin-system of the Ising type is formulated. The thermodynamic properties of this model are considered. Analytically and numerically the specific heat of this system is calculated in the nearest neighbor approximation (only the influence of two neighboring spins was taken into account). It is shown that in temperature dependence of the specific heat the log-periodic oscillations are appeared. These oscillations are imposed on the expected power-law dependence.

2012-11-29

308

An observation regarding systems which converge to steady states for all constant inputs, yet become chaotic with periodic inputs  

CERN Document Server

This note provides a general construction, and gives a concrete example of, forced ordinary differential equation systems that have these two properties: (a) for each constant input u, all solutions converge to a steady state but (b) for some periodic inputs, the system has arbitrary (for example, "chaotic") behavior. An alternative example has the property that all solutions converge to the same state (independently of initial conditions as well as input, so long as it is constant).

Sontag, Eduardo D

2009-01-01

309

GENERAL Standing, Periodic and Solitary Waves in (1 + 1)-Dimensional Caudry—Dodd—Gibbon—Sawada—Kortera System  

Science.gov (United States)

In the paper, the variable separation approach, homoclinic test technique and bilinear method are successfully extended to a (1 + 1)-dimensional Caudry—Dodd—Gibbon—Sawada—Kortera (CDGSK) system, respectively. Based on the derived exact solutions, some significant types of localized excitations such as standing waves, periodic waves, solitary waves are simultaneously derived from the (1 + 1)-dimensional Caudry—Dodd—Gibbon—Sawada—Kortera system by entrancing appropriate parameters.

Zheng, Chun-Long; Qiang, Ji-Ye; Wang, Shao-Hua

2010-12-01

310

Calculating the r^{-n} Interactions, 1<= n< 3, in a Periodic System with a Neutralizing Background Charge Density  

CERN Multimedia

The $r^{-n}$ interaction energy, $1\\leq n< 3$, for a infinitely periodic system with explicit charges and a neutralizing, uniform background charge density is derived. An Ewald based expression for this energy has an extra term proportional to the square of the total explicit charges of the system. This expression may be useful for simulations in which explicit charge neutrality does not hold or for which the total explicit charges is a fluctuating quantity.

Wu, M G

2001-01-01

311

Peakon, compacton and loop excitations with periodic behavior in KdV type models related to Schrodinger system  

International Nuclear Information System (INIS)

[en] In this Letter, the linear variable separation approach is successfully extended to (1+1)-dimensional Korteweg-de Vries (KdV) type models related to Schrodinger system. Some significant types of solitons such as compacton, peakon and loop solutions with periodic behavior are simultaneously derived from the (1+1)-dimensional soliton system by entrancing appropriate piecewise smooth functions and multivalued functions

2000-01-00

312

On a possible linkage between W-type WUMa systems and the short period RSCVn-like binaries  

International Nuclear Information System (INIS)

[en] The authors analyze the general properties of a group of WUMa-type binaries, which show RSCVn-like activity. The position of these stars in the colour-density and mass-orbital momentum diagrams is studied, but no definite answer can be given on the linkage between short period RSCVn systems (SPG) and WUMa systems with RSCVn-like activity (WWG). (Auth.)

1981-09-03

313

Peer attachment formation by systemic redox regulation with social training after a sensitive period  

Science.gov (United States)

Attachment formation is the most pivotal factor for humans and animals in the growth and development of social relationships. However, the developmental processes of attachment formation mediated by sensory-motor, emotional, and cognitive integration remain obscure. Here we developed an animal model to understand the types of social interactions that lead to peer-social attachment formation. We found that the social interaction in a sensitive period was essential to stabilise or overwrite the initially imprinted peer affiliation state and that synchronised behaviour with others based on common motivations could be a driver of peer social attachment formation. Furthermore, feeding experience with supplementation of ubiquinol conferred peer social attachment formation even after the sensitive period. Surprisingly, the experience of feeding beyond the cage window was also effective to reduce the required amount ubiquinol, suggesting that peri-personal space modulation may affect socio-emotional cognition and there by lead to attachment formation.

Koshiba, Mamiko; Karino, Genta; Senoo, Aya; Mimura, Koki; Shirakawa, Yuka; Fukushima, Yuta; Obara, Saya; Sekihara, Hitomi; Ozawa, Shimpei; Ikegami, Kentaro; Ueda, Toyotoshi; Yamanouchi, Hideo; Nakamura, Shun

2013-01-01

314

Peer attachment formation by systemic redox regulation with social training after a sensitive period.  

Science.gov (United States)

Attachment formation is the most pivotal factor for humans and animals in the growth and development of social relationships. However, the developmental processes of attachment formation mediated by sensory-motor, emotional, and cognitive integration remain obscure. Here we developed an animal model to understand the types of social interactions that lead to peer-social attachment formation. We found that the social interaction in a sensitive period was essential to stabilise or overwrite the initially imprinted peer affiliation state and that synchronised behaviour with others based on common motivations could be a driver of peer social attachment formation. Furthermore, feeding experience with supplementation of ubiquinol conferred peer social attachment formation even after the sensitive period. Surprisingly, the experience of feeding beyond the cage window was also effective to reduce the required amount ubiquinol, suggesting that peri-personal space modulation may affect socio-emotional cognition and there by lead to attachment formation. PMID:23974241

Koshiba, Mamiko; Karino, Genta; Senoo, Aya; Mimura, Koki; Shirakawa, Yuka; Fukushima, Yuta; Obara, Saya; Sekihara, Hitomi; Ozawa, Shimpei; Ikegami, Kentaro; Ueda, Toyotoshi; Yamanouchi, Hideo; Nakamura, Shun

2013-08-26

315

Peer attachment formation by systemic redox regulation with social training after a sensitive period.  

UK PubMed Central (United Kingdom)

Attachment formation is the most pivotal factor for humans and animals in the growth and development of social relationships. However, the developmental processes of attachment formation mediated by sensory-motor, emotional, and cognitive integration remain obscure. Here we developed an animal model to understand the types of social interactions that lead to peer-social attachment formation. We found that the social interaction in a sensitive period was essential to stabilise or overwrite the initially imprinted peer affiliation state and that synchronised behaviour with others based on common motivations could be a driver of peer social attachment formation. Furthermore, feeding experience with supplementation of ubiquinol conferred peer social attachment formation even after the sensitive period. Surprisingly, the experience of feeding beyond the cage window was also effective to reduce the required amount ubiquinol, suggesting that peri-personal space modulation may affect socio-emotional cognition and there by lead to attachment formation.

Koshiba M; Karino G; Senoo A; Mimura K; Shirakawa Y; Fukushima Y; Obara S; Sekihara H; Ozawa S; Ikegami K; Ueda T; Yamanouchi H; Nakamura S

2013-08-01

316

Dynamic Stability Analysis of Periodically Time-Varying Rotor System with a Transverse Crack  

Directory of Open Access Journals (Sweden)

Full Text Available Fatigue cracks may appear in horizontal rotating machinery due to periodic stresses imposed to its shaft. The investigation of stability behavior of cracked rotors can lead to proper diagnosis of machinery and to prevent possible accidents caused by the rotor failure. In this study, the dynamic stability of a rotor with a transverse crack is investigated. Models of both open and breathing cracks are developed and then used in the model of a cracked Jeffcot (de Laval) rotor. The stability of rotor motion equations represented by differential equations with periodic coefficients is investigated using Floquet theory. While both crack models show instability regions around the first un-damped frequency, sub-harmonic regions are predicted by the breathing crack models. Compared to perturbation methods frequently used to determine the stability regions, the transition matrix approach used in this study can be applied to complex models of rotors and consequently may help in the identification of cracks in rotating machinery.

Costin D. Untaroiu; Alexandrina Untaroiu; Mihail Boiangiu

2011-01-01

317

Orbital periods of cataclysmic variables identified by the SDSS. II. Measurements for six objects, including two eclipsing systems  

CERN Document Server

Continuing our work from Paper I (Southworth et al., 2006) we present medium-resolution spectroscopy and broad-band photometry of seven cataclysmic variables (CVs) discovered by the SDSS. For six of these objects we derive accurate orbital periods, all which are measured for the first time. For SDSS J013132.39+090122.2, which contains a non-radially pulsating white dwarf, we find an orbital period of 81.54 +/- 0.13 min and a low radial velocity variation amplitude indicative of an extreme mass ratio. For SDSS J205914.87+061220.4, we find a period of 107.52 +/- 0.14 min. This object is a dwarf nova and was fading from its first recorded outburst throughout our observations. INT photometry of SDSS J155531.99-001055.0 shows that this system undergoes total eclipses which are 1.5 mag deep and occur on a period of 113.54 +/- 0.03 min. A NOT light curve of SDSS J075443.01+500729.2 shows that this system is also eclipsing, on a period of 205.965 +/- 0.014 min, but here the eclipses are V-shaped and only 0.5 mag deep...

Southworth, John; Gänsicke, B T; Aungwerojwit, A; Hakala, P; De Martino, D; Lehto, H

2007-01-01

318

Sistemas de tutoramento e épocas de transplante de physalis Periods replanting and training systems of cape-gooseberry  

Directory of Open Access Journals (Sweden)

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.

Cláudia Simone Madruga Lima; Michel Aldrighi Gonçalves; Zeni Fonseca Pinto Tomaz; Andrea De Rossi Rufato; José Carlos Fachinello

2010-01-01

319

New type of $B$-periodic magneto-oscillations in a two-dimensional electron system induced by microwave irradiation  

CERN Multimedia

We observe a new type of magneto-oscillations in the photovoltage and the longitudinal resistance of a two-dimensional electron system. The oscillations are induced by microwave irradiation and are periodic in magnetic field. The period is determined by the microwave frequency, the electron density, and the distance between potential probes. The phenomenon is accounted for by coherent excitation of edge magnetoplasmons in the regions near the contacts and offers perspectives for the development of new tunable microwave and terahertz detection schemes and spectroscopic techniques.

Kukushkin, I V; Smet, J H; Mikhailov, S A; Von Klitzing, K; Aleiner, I L; Fal'ko, V I

2003-01-01

320

Comments on PPPM, FMM, and the Ewald method for large periodic Coulombic systems  

CERN Document Server

The three most common methods, Ewald, fast multipole (FMM) and the particle-particle particle-mesh (PPPM), used to compute the interactions in many body Coulombic systems are compared for single and multi-processor machines. The Ewald method is recommended for systems of a few hundred particles per processor or less. For larger systems the PPPM method is suggested. The FMM is slower and more difficult to code efficiently.

Pollock, E L; Glosli, Jim

1995-01-01

 
 
 
 
321

Equilibrium and Stability in the Transport of Intense Off-Axis Beams in Periodic Focusing Systems  

CERN Document Server

A general equation for the centroid motion of free, continuous, intense beams propagating off-axis in solenoidal periodic focusing fields is derived.* The centroid equation is found to be independent of the specific beam distribution and may exhibit unstable solutions. A new Vlasov equilibrium for off-axis beam propagation is also obtained. Properties of the equilibrium and the relevance of centroid motion to beam confinement are discussed. The effects of a conducting pipe encapsulating the beam are also investigated.** It is shown that the charge induced at the pipe may generate chaotic orbits which can be detrimental to the beam transport.

Pakter, Renato; da Silva Moraes, Jorge

2005-01-01

322

Transport and current reversal in a periodic system driven by cross-correlated noises  

Energy Technology Data Exchange (ETDEWEB)

We study the noise-induced transport and current reversal of Brownian particles in a spatially symmetric periodic potential driven by cross correlation between a multiplicative white noise and an additive white noise. We found that directed motion of the Brownian particles can be induced by the correlation between the multiplicative white noise and the additive white noise. The current reversal and the direction of the current is controlled by the values of the intensity of the noise correlation ({lambda}) and a dimensionless parameter R (R=D/Q), Q is the intensity of multiplicative noise and D is the intensity of additive noise.

Wang, C J [Department of Physics, Yunnan University, Kunming 650091 (China); Mei, D C [Department of Physics, Yunnan University, Kunming 650091 (China)

2007-08-15

323

Quasi-gradient systems, modulational dichotomies, and stability of spatially periodic patterns  

CERN Multimedia

Extending the approach of Grillakis-Shatah-Strauss, Bronski-Johnson-Kapitula, and others for Hamiltonian systems, we explore relations between the constrained variational problem $\\min_{X:C(X)=c_0} \\mathcal{E}(X)$, $c_0\\in \\RM^r$, and stability of solutions of a class of degenerate "quasi-gradient" systems $dX/dt=-M(X)\

Pogan, Alin; Zumbrun, Kevin

2012-01-01

324

Stability analysis for sampled-data systems with a time-varying period  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper deals with a new analysis of the stability of linear systems with sampled-data inputs. Inspired by the input-delay approach and the stability of impulsive systems, the proposed method provides novel stability conditions. The stability analysis concerns both constant and time-varying sampl...

Seuret, Alexandre

325

Methods of topological degree theory in Malkin I. G. - Melnikov V. K.'s problems for periodically perturbed systems  

CERN Multimedia

A topological degree based averaging principle has been proposed by J. Mawhin in his PhD thesis [J. Mawhin, Le Probleme des Solutions Periodiques en Mecanique non Lineaire, These de doctorat en sciences, Universite de Liege, 1969]. In his thesis the author gives analogous topological degree versions of classical bifurcation results due to I.G. Malkin and V.K. Melnikov, namely the conditions for bifurcation of periodic solutions from families are expressed in term of the topological degree of the bifurcation function. Moreover, the topological index of bifurcated periodic solutions is evaluated over that degree. A third part of the thesis is devoted to the rate the bifurcated periodic solutions converge when the perturbation vanishes. The differentiability of perturbed systems is not assumed.

Makarenkov, Oleg

2007-01-01

326

Aspects of the optional maintenance policy of partially testable standby-systems with periodical testing  

International Nuclear Information System (INIS)

This paper proposes a procedure of application of a method, for the optimization of the maintenance policy of partially testable standby-systems, which takes into account the disadvantageous effect of imperfect testing operations to the system availability. The application refers to the optimization procedure with respect to the time intervals between tests and with respect to the mission time of the system in the case when the failure rates during the test interval of the testable and the untestable parts of the standby-system are not given but the composition of the parts and the failure rates of their components are known. As an illustration, the proposed procedure is applied to a simplified safety injection system. (author).

1985-01-01

327

Aspects of the optional maintenance policy of partially testable standby-systems with periodical testing  

Energy Technology Data Exchange (ETDEWEB)

This paper proposes a procedure of application of a method, for the optimization of the maintenance policy of partially testable standby-systems, which takes into account the disadvantageous effect of imperfect testing operations to the system availability. The application refers to the optimization procedure with respect to the time intervals between tests and with respect to the mission time of the system in the case when the failure rates during the test interval of the testable and the untestable parts of the standby-system are not given but the composition of the parts and the failure rates of their components are known. As an illustration, the proposed procedure is applied to a simplified safety injection system.

Nicolescu, T. (Eidgenoessisches Inst. fuer Reaktorforschung, Wuerenlingen (Switzerland))

1985-01-01

328

Human error considerations in determining the optimum test interval for periodically inspected standby systems  

Energy Technology Data Exchange (ETDEWEB)

This paper incorporates the effects of two types of human error in a model for determining the optimal time between inspections for a safety system. The possibility that a bad safety system is undetected upon inspection (Type B human error), as well as the possibility that a good safety system is inadvertently left in a bad state after the inspection (Type A human error), are considered. A Markov model is developed for the steady-state availability of the safety system which is then used to determine the optimum time between inspections which either maximizes the availability or minimizes the combined inspection and unavailability costs. The safety system failure (hazard) rate need not be constant. The optimum time between inspections increases as the probability of a Type A error increases and a Type B error decreases. The optimum availability decreases and the optimum total cost increases as the error probabilities increase.

McWilliams, T.P. (Univ. of Denver, CO); Martz, H.F.

1980-10-01

329

[Ammonia metabolism during perinatal period--ontogenesis of enzymes in pyrimidine biosynthesis and urea cycle system].  

UK PubMed Central (United Kingdom)

The enzymes and intermediate metabolite of pyrimidine biosynthesis and ammonia metabolism were studied during perinatal period in rats. The activity of carbamyl phosphate synthetase I(CPS I) in fetal rat liver was low up to the 19th day of gestation, but a rapid increase was observed on the 20th day of gestation. The activity of CPS I in adult liver was about three times as high as that on the 17th day of gestation in fetal rat liver. The activities of carbamyl phosphate synthetase II(CPS II) and aspartate transcarbamylase (ATC) in fetal rat liver were much higher than those in adult liver, but a rapid decrease was observed from the 17th day of gestation up to birth. The activities of CPS II and ATC in adult liver were about 5--10% of those on the 17th day of gestation. The change in orotate content during the perinatal period in fetal rat liver was parallel to changes in the activities of CPS I and ATC, and a rapid decrease in orotate content in the last gestational stage was related to a rapid decrease in CPS and ATC activities. These results indicate that the activities of CPS I and CPS II change from the end of the gestational stage up to birth, and the proposed metabolic regulation of fetal growth and developments of considerable interest.

Nagasaki T

1984-12-01

330

Progress report of the CEC project Rodos system development. Period: 1 september 92-31 august 93  

International Nuclear Information System (INIS)

[en] 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

331

Promotion of grid-connected photovoltaic systems in Spain: Performance analysis of the period 1998-2008  

Energy Technology Data Exchange (ETDEWEB)

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)

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

332

Electrostatic interactions in finite systems treated with periodic boundary conditions: application to linear-scaling density functional theory.  

Science.gov (United States)

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. PMID:22128924

Hine, Nicholas D M; Dziedzic, Jacek; Haynes, Peter D; Skylaris, Chris-Kriton

2011-11-28

333

Periodic and Solitary Wave Solutions of Two Component Zakharov-Yajima-Oikawa System, Using Madelung's Approach  

Directory of Open Access Journals (Sweden)

Full Text Available Using the multiple scales method, the interaction between two bright and one dark solitons is studied. Provided that a long wave-short wave resonance condition is satisfied, the two-component Zakharov-Yajima-Oikawa (ZYO) completely integrable system is obtained. By using a Madelung fluid description, the one-soliton solutions of the corresponding ZYO system are determined. Furthermore, a discussion on the interaction between one bright and two dark solitons is presented. In particular, this problem is reduced to solve a one-component ZYO system in the resonance conditions.

Anca Visinescu; Dan Grecu; Renato Fedele; Sergio De Nicola

2011-01-01

334

Medicaid management information systems performance standards: Health Care Financing Administration. Notice with comment period.  

UK PubMed Central (United Kingdom)

This notice contains performance standards (review elements and factors). We are required by section 1903(r)(6)(E) of the Social Security Act to notify all States of proposed procedures, standards, and other requirements at least one quarter prior to the fiscal year in which the procedures, standards, and other requirements will be used for Medicaid Management Information Systems reapproval reviews. This Notice meets that statutory requirements. By October 1, 1981, we will use the performance standards and existing systems requirements when conducting the annual review of State system performance.

1981-06-01

335

Orbital stability for periodic standing waves of the Klein-Gordon-Zakharov system and the beam equation  

Science.gov (United States)

The existence and stability of spatially periodic waves {(e^{i{?}t}\\varphi_?, ?_?)} in the Klein-Gordon-Zakharov (KGZ) system are studied. We show a local existence result for low regularity initial data. Then, we construct a one-parameter family of periodic dnoidal waves for (KGZ) system when the period is bigger than {sqrt{2}?} . We show that these waves are stable whenever an appropriate function satisfies the standard Grillakis-Shatah-Strauss (Grillakis et al. J Funct Anal 74(1):160-197, 1987; Grillakis et al. J Funct Anal 94(2):308-348, 1990) type condition. We compute the intervals for the parameter ? explicitly in terms of L and by taking the limit L ? ? we recover the previously known stability results for the solitary waves in the whole line case. For the beam equation, we show the existence of spatially periodic standing waves and show that orbital stability holds if an appropriate functional satisfies Grillakis-Shatah-Strauss type condition.

Hakkaev, Sevdzhan; Stanislavova, Milena; Stefanov, Atanas

2013-04-01

336

Dynamic Scheduling of Skippable Periodic Tasks With Energy Efficiency In Weakly Hard Real-Time System  

Directory of Open Access Journals (Sweden)

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 (RLP)are 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.

Santhi Baskaran; P. Thambidurai

2010-01-01

337

Floquet states and quasienergies of a periodically driven two-level system  

International Nuclear Information System (INIS)

We investigate the Floquet states and quasienergies of a two-level quantum system driven by a high-frequency driving field. This quantum system is mapped onto a classical one in a function transformation. The Floquet states and quasienergies are calculated in a multiple scale expansion in the inverse of the frequency (?) to order ?-2. It is shown that the coherent destruction of tunnelling is a second-order effect.

2009-05-28

338

Structure and Evolution of Nearby Stars with Planets; 1, Short-Period Systems  

CERN Multimedia

Using the Yale stellar evolution code, we have calculated theoretical models for nearby stars with planetary-mass companions in short-period nearly circular orbits: 51 Pegasi, Tau Bootis, Upsilon Andromedae, Rho Cancri, and Rho Coronae Borealis. We present tables listing key stellar parameters such as mass, radius, age, and size of the convective envelope as a function of the observable parameters (luminosity, effective temperature, and metallicity), as well as the unknown helium fraction. For each star we construct best models based on recently published spectroscopic data and the present understanding of galactic chemical evolution. We discuss our results in the context of planet formation theory, and, in particular, tidal dissipation effects and stellar metallicity enhancements.

Ford, E B; Sills, A; Ford, Eric B.; Rasio, Frederic A.; Sills, Alison

1999-01-01

339

Investigation of layered systems and temperature-dependent thermophysical characterization by photothermal methods with periodic excitation  

Science.gov (United States)

The salient features of periodically modulated photoacoustic (PA), photothermal radiometry (PTR) and photopyroelectric (PPE) methods are reviewed with emphasis on their use for characterization of layered samples. Using a general one-dimensional (1-D) heat diffusion model, explicit solutions for up to six layers are given in terms of thermal impedances. Two typical model configurations can be transformed and combined using symmetry properties in order to match a particular excitation/cell configuration couple. Different special cases allow for simultaneous measurement of two thermal parameters. For temperature-dependent investigations the direct temperature-conversion feature of the PPE method is advantageous. We show results on the temperature calibration of LiTaO3 and PVDF pyroelectric sensors.

Chirtoc, M.

2010-03-01

340

Light curve solutions and study of roles of magnetic fields in period variations of the UV Leo system  

Directory of Open Access Journals (Sweden)

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.

D Manzoori

2009-01-01

 
 
 
 
341

Nonlinear generalization of the Floquet theorem and an adiabatical theorem for dynamical systems with Hamiltonian periodic in time  

International Nuclear Information System (INIS)

The aim of this paper is to extend the theory of adiabatical invariance to classical Hamiltonian systems with time-periodic potentials or constraints. Such a generalization has been already performed in quantum mechanics (and later on extensively applied, namely in statistical mechanics) but it was based on the Floquet theorem, i.e., use was made of the linearity of the field equations. We show, in the present paper that the main idea of the Floquet theorem can be expressed in a non-linear way. We then introduce in analytical dynamics a new concept called canonical reducibility, which is a non-linear extension of Floquet theorem and we provide a theorem asserting that a dynamical periodic system which is canonically reducible to a conservative and integrable one possesses adiabatical invariants

1980-08-09

342

Data Quality Monitoring for the ATLAS trigger System during the first data taking period of the Large Hadron Collider  

CERN Document Server

The first long period of data taking of the Large Hadron Collider was finished after 2 years of data in February 2013. The increase of the instantaneous luminosity by more than six orders of magnitude documents impressively the extraordinary success of this running period enabling the ATLAS experiment to collect data of very high quality. However, to ensure a constant and reliable monitoring and data quality assessment of the trigger's point of view, a highly flexible and powerful software framework is essential, covering many different aspects. Aside from drastically changing beam conditions as e.g. increasing pile up, the monitoring frame work has to follow up immediately and flexible all developments of the TDAQ system. The TDAQ monitoring system of ATLAS covers very different aspects as rate measurements, trigger configuration and software tests, data quality assessment and handling of events where the trigger decision has failed. Especially the data quality assessment must be made coherent at the online ...

Damazio, D O; The ATLAS collaboration

2013-01-01

343

Data Quality Monitoring for the ATLAS trigger System during the first data taking period of the Large Hadron Collider  

CERN Multimedia

The first long period of data taking of the Large Hadron Collider was finished after 3 years of work in February 2013. The increase of the instantaneous luminosity by more than six orders of magnitude documents impressively the extraordinary success of this running period enabling the ATLAS experiment to collect very high quality data. However, to ensure a constant and reliable monitoring and data quality assessment from the trigger's point of view, a highly flexible and powerful software framework is essential, covering many different aspects. Aside from drastically changing beam conditions as e.g. increasing pile up, the monitoring frame work has to follow up immediately and in a flexible manner all developments of the TDAQ system. The TDAQ monitoring system of ATLAS covers very different aspects as rate measurements, trigger configuration and software tests, data quality assessment and handling of events where the trigger decision has failed. Especially the data quality assessment must be made coherent at ...

Oliveira Damazio, Denis; The ATLAS collaboration

2013-01-01

344

Fuel Cell/Battery Powered Bus System. Final Report for period August 1987 - December 31, 1997  

Energy Technology Data Exchange (ETDEWEB)

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.

Wimmer, R.

1999-01-01

345

Long Period Tidal Force Variations and Regularities in Orbital Motion of the Earth-Moon Binary Planet System  

CERN Multimedia

We have studied long period, 206 and 412 day, variations in tidal sea level corresponding to various moon phases collected from five observatories in the Northern and Southern hemispheres. Variations in sea level in the Bay of Fundy, on the eastern Canadian seaboard, with periods of variation 206 days, and 412 days, have been discovered and carefully studied by C. Desplanque and D. J. Mossman (2001, 2004). The current manuscript focuses on analyzing a larger volume of observational sea level tide data as well as on rigorous mathematical analysis of tidal force variations in the Sun-Earth-Moon system. We have developed a twofold model, both conceptual and mathematical, of astronomical cycles in the Sun-Earth-Moon system to explain the observed periodicity. Based on an analytical solution of the tidal force variation in the Sun-Earth-Moon system, it is shown that the tidal force can be decomposed into two components: the Keplerian component and the Perturbed component. The Perturbed component of the tidal force...

Avsyuk, Yu N; 10.1007/s11038-011-9381-8; 10.1007/s11038-011-9381-8

2012-01-01

346

Interfacial chemistry in solvent extraction systems: Progress report for period April 1, 1986-March 31, 1987  

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.

1986-01-01

347

Almost All S-Integer Dynamical Systems Have Many Periodic Points  

UK PubMed Central (United Kingdom)

We show that for almost every ergodic S--integer dynamical systemthe radius of convergence of the dynamical zeta function is no larger thanexp(Gamma12 htop ) ! 1. In the arithmetic case almost every zeta function is irrational.We conjecture that for almost every ergodic S--integer dynamical systemthe radius of convergence of the zeta function is exactly exp(Gammah top ) ! 1 andthe zeta function is irrational.In an important geometric case (the S--integer systems corresponding toisometric extensions of the full p--shift or, more generally, linear algebraic cellularautomata on the full p--shift) we show that the conjecture holds with thepossible exception of at most two primes p.Finally we explicitly describe the structure of S--integer dynamical systemsas isometric extensions of (quasi--)hyperbolic dynamical systems.1. IntroductionThe S--integer dynamical systems were introduced in [3], and the question oftypical behaviour for one family of these systems was cons...

T. B. Ward

348

Double scale expansion of periodic solutions of some vibrating systems, with non linear springs  

CERN Multimedia

We consider small solutions of a system with smooth non-linearities for which we provide an approximate solution by using double scale technique; a rigorous proof of convergence of the double scale method is included; for the forced response, a stability result is needed in order to prove convergence in a neighborhood of a primary resonance.

Brahim, Nadia Ben

2013-01-01

349

Automated Load Shedding Period Control System (An effective way to reduce human effort)  

Directory of Open Access Journals (Sweden)

Full Text Available Energy is the basic necessity for the economic development of a country. Many functions necessary to present-day living grind to halt when the supply of energy stops. It is practically impossibleto estimate the actual magnitude of the role that energy has played in building up present-day civilization. In this modern world, the dependence on electricity is so much that it has become a PART & PARCEL of our life. So we need to save more & more electrical power. Hence, the load shedding control system, which was earlier done manually, now-a-days, is controlled by a computer based system, developed to some more extent to direct the society to a more convenient life. This paper focuses on developing a computerized procedure for controlling the load-shedding system where manual work will be minimized by selecting the feeder, substation and duration of shedding time by the user. Simulation results’, using the above proposed model, verifies the suitability of choosing such an automated load shedding system.

Dwijen Rudrapal,; Smita Das,; Agnivesh Pandey,; Nirmalya Kar

2011-01-01

350

Cooling Fan and System Performance and Efficiency Improvements. Reporting Period: June 1, 2002-July 31, 2005.  

Science.gov (United States)

This report contains six tasks. They are: Develop an axial fan that will provide more airflow, with less input power and less noise; Develop for chine use, an 'aseroshroud' concept developed at Michigan State University; Improve the axial fan system model...

G. T. Eyck J. Harper J. McClain M. Thomas R. Dupree

2005-01-01

351

The existence and multiple periodic solutions for generalized asymptotical linear Hamiltonian systems without convexity condition  

Directory of Open Access Journals (Sweden)

Full Text Available This paper consider the existence and multiplicity of solutions forthe first order Hamiltonian systems satisfying Sturm-Liouville boundaryconditions without convexity assumption. The gradient of Hamiltonianfunction is generalized asymptotically linear. We find critical points ofthe corresponding functional by verifying the assumptions of Theoremsabout critical points given by Bartsch and Ding in [1].

Yuan Shan

2013-01-01

352

Novel use of intrathecal baclofen drug delivery system for periodic focal dystonia in a teenager.  

UK PubMed Central (United Kingdom)

INTRODUCTION: ?Focal dystonia, often affecting part of a limb, is a manifestation of complex regional pain syndrome (CRPS). This can be difficult to diagnose and treat. Furthermore, there may be significant latency between the onset of dystonia after the diagnosis of CRPS. We present the case of a 15-year-old girl with periodic focal dystonia who has been successfully treated with an intrathecal baclofen pump. MATERIALS AND METHODS: ?The patient had sustained a minor ankle fracture four years prior to presentation. Despite radiologic evidence of adequate bony union, the patient continued to complain of spasms and pain in her left foot leading to dystonic posturing of the foot. Multiple therapies including subcutaneous morphine infusion, ankle splinting, physiotherapy, and local botulinum injections had not provided adequate relief. Intrathecal baclofen on three separate occasions resulted in successful temporary resolution of the dystonia. A placebo double-blinded injection of intrathecal saline at a separate setting however did not resolve the dystonia. RESULTS: ?We then proceeded with permanent delivery of baclofen by implantation of an intrathecal drug delivery pump, which resulted in resolution of the dystonia. The patient also was able to receive bolus doses of intrathecal baclofen. The patient is now able to partake in sporting and dancing activities. A detailed history of the patient, along with the difficulties in diagnosis and management, is presented. CONCLUSION: ?Intrathecal baclofen therapy can be effective in the management of focal dystonia after rigorous preoperative testing and counseling of adolescents with CRPS.

Bahl A; Tripathi C; McMullan J; Goddard J

2013-05-01

353

The Beginning of Parlementer System And The Situation of K?r?ehir In This Period  

Directory of Open Access Journals (Sweden)

Full Text Available The hard arguments between Adnan Menderes from DP and Osman Bölükba?? from MP, the founding of Republican Nation Party in February,1954 and opening the first branch by defragmenting with Osman Bölükba?? and contending with election campaign and meetings and the result of 2nd of May, 1954 elections became the determining factor of becoming county of K?r?ehir.In 1957 government came into action for alleviating the being against of K?r?ehir and became the preparation for making the convince the K?r?ehir again and prepared the government bill. The law that was published on the official gazette that is numbered 9637 and dated 19th of June, 1957 and is admission dated 12th of June,1957 about refounding a new convince called K?r?ehir in K?r?ehir county affiliated with Nev?ehir province.K?r?ehir held a place in Turkish political life and democracy with the developments that became in this period.

Assist. Prof. Dr. Ya?ar ÖZÜÇET?N

2008-01-01

354

The Earth-Moon system during the Late Heavy Bombardment period  

CERN Document Server

The Late Heavy Bombardment (LHB) period is the narrow time interval between 3.8 and 3.9 Gyr ago, where the bulk of the craters we see on the Moon formed. Even more craters formed on the Earth. During a field expedition to the 3.8 Gyr old Isua greenstone belt in Greenland, we sampled three types of metasedimentary rocks, that contain direct traces of the LHB impactors by a seven times enrichment (150 ppt) in iridium compared to present day ocean crust (20 ppt). We show that this enrichment is in agreement with the lunar cratering rate, providing the impactors were comets, but not if they were asteroids. Our study is a first direct indication of the nature of the LHB impactors, and the first to find an agreement between the LHB lunar cratering rate and the Earth's early geochemical record (and the corresponding lunar record). The LHB comets that delivered the iridium we see at Isua will at the same time have delivered the equivalent of a km deep ocean, and we explain why one should expect a cometary ocean to be...

Jorgensen, Uffe Graae; Hatsukawa, Yuichi; Frei, Robert; Oshima, Masumi; Toh, Yosuke; Kimura, Atsushi

2009-01-01

355

Evidence for the validity of the Berry-Robnik surmise in a periodically pulsed spin system  

CERN Multimedia

We study the statistical properties of the spectrum of a quantum dynamical system whose classical counterpart has a mixed phase space structure consisting of two regular regions separated by a chaotical one. We make use of a simple symmetry of the system to separate the eigenstates of the time-evolution operator into two classes in agreement with the Percival classification scheme \\cite{Per}. We then use a method firstly developed by Bohigas et. al. \\cite{BoUlTo} to evaluate the fractional measure of states belonging to the regular class, and finally present the level spacings statistics for each class which confirm the validity of the Bery-Robnik surmise in our model.

Jacquod, P; Jacquod, Ph

1995-01-01

356

Near action degeneracy of periodic orbits in systems with non-conventional time reversal  

CERN Document Server

Recently, Sieber and Richter calculated semiclassically a first off-diagonal contribution to the orthogonal form factor for a billiard on a surface of constant negative curvature by considering orbit pairs having almost the same action. For a generalization of this derivation to systems invariant under non-conventional time reversal symmetry, which also belong to the orthogonal symmetry class, we show in this paper that it is necessary to redefine the configuration space in an appropriate way.

Braun, P A; Heusler, S

2001-01-01

357

A general formalism for quasi-local correction of multipole distortions in periodic transport systems  

International Nuclear Information System (INIS)

We generalize a new concept of local correction of nonlinearities due to multipole content by giving it a mathematical description. We present a general method which allows for a general reduction of all the distortions produced by a given set of multipole errors. The method can be applied to correct an arbitrary distribution of the errors in any transport system, such as transport lines, linacs, synchrotrons and storage rings. 11 refs., 3 figs., 2 tabs

1988-01-01

358

Time dependent unavailability analysis of nuclear safety systems considering periodically tested components  

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)

1988-01-01

359

A Meeting of Two Chronobiological Systems: Circadian Proteins Period1 and BMAL1 Modulate the Human Hair Cycle Clock.  

UK PubMed Central (United Kingdom)

The hair follicle (HF) is a continuously remodelled mini-organ that cycles between growth (anagen), regression (catagen) and relative quiescence (telogen). Since the anagen-catagen transformation of micro-dissected human scalp HFs can be observed in organ culture permits the study of the unknown controls of autonomous, rhythmic tissue remodelling of the HF which intersects developmental, chronobiological and growth-regulatory mechanisms. The hypothesis, that the peripheral clock system is involved in the hair cycle transition, i.e. the anagen-to-catagen transformation, was tested. We show that, in the absence of central clock influences, isolated, organ-cultured human HFs show circadian changes in the gene and protein expression of core clock genes (CLOCK, BMAL1, Period1) and clock-controlled genes (c-Myc, NR1D1, CDKN1A), with Period1 expression being hair cycle-dependent. Knock-down of either BMAL1 or Period1 in human anagen HFs significantly prolonged. This provides evidence that peripheral core clock genes modulate human HF cycling, and are an integral component of the human hair cycle clock. Specifically, our study identifies BMAL1 and Period1 as potential therapeutic targets for modulating human hair growth.Journal of Investigative Dermatology accepted article preview online, 4 September 2013; doi:10.1038/jid.2013.366.

Al-Nuaimi Y; Hardman JA; Bíró T; Haslam IS; Philpott M; Tóth BI; Farjo N; Farjo B; Baier G; Watson RE; Grimaldi B; Kloepper JE; Paus R

2013-09-01

360

Toward an international consensus strategy for periodic quality control of digital breast tomosynthesis systems  

Science.gov (United States)

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.

Jacobs, J.; Marshall, N.; Cockmartin, L.; Zanca, F.; van Engen, R.; Young, K.; Bosmans, H.; Samei, E.

2010-03-01

 
 
 
 
361

Los Alamos plutonium facility applied systems integration project status report for period ending August 31, 1981  

International Nuclear Information System (INIS)

[en] 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

1982-01-01

362

Los Alamos plutonium facility applied systems integration project status report for period ending August 31, 1981  

Energy Technology Data Exchange (ETDEWEB)

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.

Shirk, D.G.; Bearse, R.C.; Marshall, R.S.; Baker, A.L.; Thomas, C.C. Jr.

1982-02-01

363

Threshold dynamics for periodically forced ecological systems: the control of population invasion and exclusion.  

UK PubMed Central (United Kingdom)

Ecosystems are under increasing threat as a result of anthropogenic activity, through pollution, unregulated harvesting, habitat destruction and the inadvertent spread of pathogens and vertebrate and non-vertebrate species through global transportation links. Many of the necessary interventions to restore or restructure natural ecosystems require the exclusion of a population from the ecosystem or the inclusion of a population if robust biodiversity is the objective. The problem of how best to bring this about is not easy to solve in highly nonlinear systems, especially if the system is exposed to significant time varying external forces. We wish here to build on the understanding gained from previous work by developing an algebraic methodology that yields explicit formulae to analyse the effect of moderate multi-component forcing on the invasion/exclusion process. This can be of assistance to management in designing suitable intervention strategies if one or more of the forcing components is under management control. We apply this methodology to look at three important issues, involving the relationships between resonance and control, between vaccination policy and the stage structure of a disease and between apparent competition and coexistence.

Greenman JV; Pasour VB

2012-02-01

364

Interfacial chemistry in solvent extraction systems: Progress report for period April 1, 1985-March 31, 1988  

Energy Technology Data Exchange (ETDEWEB)

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/CaCl/sub 2/ solution. These techniques were further extended to include different organophosphorus acids (PC 88A and CYANEX 272), diluent (benzene), and metal ions (Co/sup 2 +/, Ni/sup 2 +/, and Zn/sup 2 +/) 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.

Neuman, R.D.

1987-11-01

365

Interfacial chemistry in solvent extraction systems: Progress report for period April 1, 1985-March 31, 1988  

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.

1987-01-01

366

Continuous solid solution of {kappa}-phase in the third period transition metals-aluminum-carbon pseudo-ternary systems  

Energy Technology Data Exchange (ETDEWEB)

Phase stability of {kappa}-phases (perovskite-type phases) was studied in the third-period transition-metals (M: Mn to Cu) - aluminum (Al) - carbon (C) systems. The concentrations of transition metals (C{sub M}) were systematically changed from 60mol%Mn to 20mol%Ni+40mol%Cu along the periodic table under the constant nominal alloy compositions of C{sub M1}+C{sub M2} = 60mol%, C{sub Al} = 20mol% and C{sub C} = 20mol%. Alloys were prepared using mechanical alloying and hot pressing. Constituent phases were investigated by X-ray diffraction analysis, scanning electron microscopy and electron probe microanalysis. It is confirmed that Mn{sub 3}Al(C,O){sub 0.95}, Fe{sub 3}Al(C,O){sub 0.87}, Co{sub 3}Al(C,O){sub 0.6} and Ni{sub 3}Al(C,O){sub 0.26} exist in their ternary systems where oxygen is introduced during the process. Also, only one {kappa}-phase is recognized in an alloy having an intermediate composition in every system. This suggests that continuous solid solutions between these {kappa}-phases are formed in the pseudo-ternary systems. Composition dependence of lattice parameter is discussed.

Hosoda, Hideki; Suzuki, Kensyo; Hanada, Shuji

1999-07-01

367

Orbitas periodicas em sistemas hamiltonianos nao integraveis com dois graus de liberdade. (Periodic orbits in non-integrable hamiltoniam systems with two degrees of freedom).  

Science.gov (United States)

We present extensive numerical data concerning the periodic orbits of a non integrable two degrees of freedom hamiltoniam system. These periodic orbits form a one-parameter family and the data are displayed in a plot of energy x period. These orbits exhib...

M. A. M. Aguiar

1987-01-01

368

Mitral restenosis in the early postoperative period of a patient with systemic lupus erythematosus  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english 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 (more) 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 .

Pomerantzeff, Pablo Maria Alberto; Corrêa, Jeanne D'Arc Honória; Brandão, Carlos Manuel de Almeida; Assis, Raimunda Violante Campos de; Jatene, Adib Domingos

1999-04-01

369

Mitral restenosis in the early postoperative period of a patient with systemic lupus erythematosus  

Directory of Open Access Journals (Sweden)

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 .

Pomerantzeff Pablo Maria Alberto; Corrêa Jeanne D'Arc Honória; Brandão Carlos Manuel de Almeida; Assis Raimunda Violante Campos de; Jatene Adib Domingos

1999-01-01

370

On the development of instability of the black hole-torus systems and quasi periodic oscillations  

CERN Document Server

We present the numerical study of dynamical instability of a pressure-supported relativistic torus, rotating around the black hole with a constant specific angular momentum on a fixed space-time background, in case of perturbation by a matter coming from the outer boundary. Two dimensional general relativistic hydrodynamical equations are solved at equatorial plane using the HRSCS to study the effect of perturbation on the stable systems. We have found that the perturbed torus creates an instability which causes the gas falling into the black hole in a certain dynamical time. All the models indicate an oscillating torus with certain frequency around their instant equilibrium. The dynamic of accreted torus varies with the size of initial stable torus, black hole spin and other variables, such as Mach number, sound speed, initial radius of the torus etc., but not their instability. The precessing torus not only effects the gravitational radiation, but also generates it. On the other hand, the mass accretion rat...

Donmez, Orhan

2013-01-01

371

The problem of oxidation state stabilisation and some regularities of a Periodic system of the elements  

Energy Technology Data Exchange (ETDEWEB)

The general principles of the concept of oxidation state stabilisation are formulated. Problems associated with the preparation and provision of the highest valent forms of transition elements are considered. The empirical data concerning the synthesis of new compounds of rare-earth elements and d elements in unusually high oxidation states are analysed. The possibility of occurrence of the oxidation states + 9 and + 10 for some elements (for example, for iridium and platinum in tetraoxo ions) are discussed. Approaches to the realisation of these states are outlined and it is demonstrated that solid phases or matrices containing alkali metal cations are the most promising systems for the stabilisation of these high oxidation states. Selected thermodynamic features typical of metal halides and oxides and the regularities of the changes in the extreme oxidation states of d elements are considered. The bibliography includes 266 references.

Kiselev, Yurii M; Tretyakov, Yuri D [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

1999-05-31

372

Implementation of empirical dispersion corrections to density functional theory for periodic systems.  

UK PubMed Central (United Kingdom)

A recently developed empirical dispersion correction (Grimme et al., J. Chem. Phys. 2010, 132, 154104) to standard density functional theory (DFT-D3) is implemented in the plane-wave program package VASP. The DFT-D3 implementation is compared with an implementation of the earlier DFT-D2 version (Grimme, J. Comput. Chem. 2004, 25, 1463; Grimme, J. Comput. Chem. 2006, 27, 1787). Summation of empirical pair potential terms is performed over all atom pairs in the reference cell and over atoms in shells of neighboring cells until convergence of the dispersion energy is obtained. For DFT-D3, the definition of coordination numbers has to be modified with respect to the molecular version to ensure convergence. The effect of three-center terms as implemented in the original molecular DFT-D3 version is investigated. The empirical parameters are taken from the original DFT-D3 version where they had been optimized for a reference set of small molecules. As the coordination numbers of atoms in bulk and surfaces are much larger than in the reference compounds, this effect has to be discussed. The results of test calculations for bulk properties of metals, metal oxides, benzene, and graphite indicate that the original parameters are also suitable for solid-state systems. In particular, the interlayer distance in bulk graphite and lattice constants of molecular crystals is considerably improved over standard functionals. With the molecular standard parameters (Grimme et al., J. Chem. Phys. 2010, 132, 154104; Grimme, J. Comput. Chem. 2006, 27, 1787) a slight overbinding is observed for ionic oxides where dispersion should not contribute to the bond. For simple adsorbate systems, such as Xe atoms and benzene on Ag(111), the DFT-D implementations reproduce experimental results with a similar accuracy as more sophisticated approaches based on perturbation theory (Rohlfing and Bredow, Phys. Rev. Lett. 2008, 101, 266106).

Reckien W; Janetzko F; Peintinger MF; Bredow T

2012-09-01

373

Stability and sensitivity of the stability of periodically timevariant systems in rotor-dynamics. Die Stabilitaet und die Empfindlichkeit der Stabilitaet periodisch zeitvarianter Systeme in der Rotordynamik  

Energy Technology Data Exchange (ETDEWEB)

Technical systems which can be described by periodical timevariant equations of motion sometimes show an unstable behaviour at certain constellations of parameters without an external excitation. The stability analysis for such systems via Floquet and via Hill are shortly described and compared. Thereafter it will be shown, how the stability behaviour caused by changes of parameters can be determined without analysing the stability completely new. As practical examples two one-bladed wind turbines with see-saw propellers are considered. (orig.).

Wiedemann, M.; Person, M. (Technische Univ. Berlin (Germany). Inst. fuer Luft- und Raumfahrt)

1992-09-01

374

Singularity Structure Analysis of the Higher-Dimensional Time-Gated Manakov System: Periodic Excitations and Elastic Scattering  

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)

2010-01-01

375

Element separation before matter accretion of solar system planets in the light of the periodic law  

International Nuclear Information System (INIS)

The proofs of element separation in protoplanet nebula of Protosolar system have been found. For this purpose the K1/K2 ratios of concentration of elements - chemical analogs in the rock samples of Venus, Earth, Mars and meteorites were compared. The new approach enabled the comparison of K1/K2 of the Earth and meteorites with K1/K2 of Venus and Mars obtained by elemental analysis of their rock samples. It has been found that at J2/J1>1 chemical analogs have K1/K2: on Venus probably less or at least commeasurable, on Mars and, especially in meteorites, considerably (several orders of magnitude) greater than in the Earth rocks (J1 and J2 are charged atoms fractions in photon flux of the Protosun). Other facts, which agree with the relationship K1/K2=f(R), where R is the average distance of a body from the Sun, were found. 41 refs.; 1 fig.; 5 tabs

1990-01-01

376

Multi-periodic pulsations of a stripped red-giant star in an eclipsing binary system.  

UK PubMed Central (United Kingdom)

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.

Maxted PF; Serenelli AM; Miglio A; Marsh TR; Heber U; Dhillon VS; Littlefair S; Copperwheat C; Smalley B; Breedt E; Schaffenroth V

2013-06-01

377

Existence of lattice solutions to semilinear elliptic systems with periodic potential  

Directory of Open Access Journals (Sweden)

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.

Nicholas D. Alikakos; Panayotis Smyrnelis

2012-01-01

378

Experimental study of the systems of induction accelerators of enhanced cycle periodicity. The SILUND 2  

International Nuclear Information System (INIS)

[en] The results of experimental study on the new collective accelerator injector-linear induction electron accelerator with the cycle repetition frequency of 50Hz - are given. Accelerating section consisting of 24 inductors on ferrites K 250x170x25 200 HH2 is able to create the accelerating field with the intensity of 4,5-5 kV/cm. Modulator supplying the accelerating section operates with one thyratron TGH-2500/5 and forms the 350 kV pulses with the duration of 30-40 ns at the current in load of 1000-1200 A. The elaborated supply system of the focusing coils shapes the current pulses of 1,5-2 kA with the duration of 40-50 ?s with the frequency 50 Hz in the focusing coils forming longitudinal magnetic field with the intensity of 2-3 kOe. The device analogous to the source operating at SILUND accelerator is used as the electron source. Resulting in the tuning and adjustment of the electron source jointly with the accelerating section, the electron beam with the current of 1000 A at the frequency of 50 Hz has been obtained

1979-01-01

379

Finite Elements for a Beam System With Nonlinear Contact Under Periodic Excitation  

CERN Document Server

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...

Hazim, Hamad

2009-01-01

380

Finite elements for a beam system with nonlinear contact under periodic excitation  

Science.gov (United States)

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 maximum of displacements corresponding to each frequency. Numerical results are compared with exact solutions in particular cases which already exist in the literature. On the other hand, a numerical and theoretical investigation of nonlinear normal mode (NNM) can be a new method to describe nonlinear behaviors, this work is in progress.

Hazim, H.; Rousselet, B.

 
 
 
 
381

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.

1991-01-01

382

Value of a modified early obstetric warning system (MEOWS) in managing maternal complications in the peripartum period: an ethnographic study.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To explore implementation of the modified early obstetric warning system (MEOWS) in practice to further understanding about the influence of contextual factors. METHODS: An ethnographic study using observations (>120 h), semi-structured interviews (n=45) and documentary review was performed in the maternity services in two UK hospitals over a 7-month period. Doctors, midwives and managers participated in the study and data were analysed thematically. RESULTS: For women admitted to hospital in the antenatal and postnatal period with an established risk of morbidity, the MEOWS enabled communication about vital signs from junior to senior midwives and obstetricians. The trigger prompts helped shape shared understandings of maternal complications. However, midwifery and obstetric staff questioned the added value of an extra chart in the postnatal period given the low incidence of maternal complications and the resulting increase in workload. In an effort to prioritise workload demands and respond to the immediate needs of both women and their babies, midwives exercised professional discretion regarding its use. However, discretionary use of MEOWS meant the loss of a potential universal safety net for detection of deterioration. CONCLUSIONS: Despite a decade of use in acute settings, research into the effectiveness of early warning systems still yields conflicting results. Widespread policy support for the MEOWS is based on its intuitive appeal and no validated system for use in the maternity population currently exists. Our findings suggest that, while the MEOWS has value in structuring the surveillance of hospitalised women with an established risk of morbidity, the complexities of managing risk and safety within the maternity pathway, the associated opportunity costs of MEOWS and variation in implementation currently call into question its role for routine use.

Mackintosh N; Watson K; Rance S; Sandall J

2013-07-01

383

Nonlinear dynamics of fluid-structure systems. Final technical report for period January 5, 1991 - December 31, 1997  

Energy Technology Data Exchange (ETDEWEB)

The technical research was directed at problems involving the dynamics of fluid flow and elastic structures. Such problems occur in heat-exchange systems in energy generating plants. Fluid excited vibrations of structures can result in unwanted impact forces which can lead to metal fatigue failures. Mathematical theories based on linear models have been used for several decades. In this research the authors explored the phenomena associated with nonlinear effects using experimental models, mathematical models and numerical computation. A number of nonlinear effects were observed experimentally including chaotic dynamics, multi-fractal Poincare maps, quasi-periodic vibrations, subcritical Hopf bifurcations, helical waves in a tube row and spatial localization.

Moon, Francis C.

1999-07-20

384

Implementation of screened hybrid density functional for periodic systems with numerical atomic orbitals: basis function fitting and integral screening.  

UK PubMed Central (United Kingdom)

We present an efficient O(N) implementation of screened hybrid density functional for periodic systems with numerical atomic orbitals (NAOs). NAOs of valence electrons are fitted with gaussian-type orbitals, which is convenient for the calculation of electron repulsion integrals and the construction of Hartree-Fock exchange matrix elements. All other parts of Hamiltonian matrix elements are constructed directly with NAOs. The strict locality of NAOs is adopted as an efficient two-electron integral screening technique to speed up calculations.

Shang H; Li Z; Yang J

2011-07-01

385

Implementation of screened hybrid density functional for periodic systems with numerical atomic orbitals: basis function fitting and integral screening.  

Science.gov (United States)

We present an efficient O(N) implementation of screened hybrid density functional for periodic systems with numerical atomic orbitals (NAOs). NAOs of valence electrons are fitted with gaussian-type orbitals, which is convenient for the calculation of electron repulsion integrals and the construction of Hartree-Fock exchange matrix elements. All other parts of Hamiltonian matrix elements are constructed directly with NAOs. The strict locality of NAOs is adopted as an efficient two-electron integral screening technique to speed up calculations. PMID:21786990

Shang, Honghui; Li, Zhenyu; Yang, Jinlong

2011-07-21

386

Periodic Review Probabilistic Multi-Item Inventory System with Zero Lead Time under Constraints and Varying Order Cost  

Directory of Open Access Journals (Sweden)

Full Text Available This study treats the probabilistic safety stock n-items inventory system having varying order cost and zero lead-time subject to two linear constraints. The expected total cost is composed of three components: the average purchase cost; the expected order cost and the expected holding cost. The policy variables in this model are the number of periods Nr* and the optimal maximum inventory level Qmr* and the minimum expected total cost. We can obtain the optimal values of these policy variables by using the geometric programming approach. A special case is deduced and an illustrative numerical example is added.

Hala A. Fergany

2005-01-01

387

On the common trend of temperature dependences of mechanical properties of metals in various groups of the Periodic system  

International Nuclear Information System (INIS)

Temperature dependences of mechanical properties are analyzed for the metals (Sc, Zr, Hf, V, Ta, Mo, W, Os and others) which can be used as binding materials in hard alloys. Melting points of the metals selected are above 1500 deg C. It is shown that the same structure of valence shells in atoms combining elements into Periodic system groups suggests that not only physical and chemical but mechanical properties as well are similar for metals of a given group at equal homologous temperatures. Approximating dependences of coefficients of actual strength variation with temperature are presented for various group metals

2006-01-01

388

Derivation of Phase Dynamics in Non-Locally Distributed Systems with Periodic Structures in Either Space or Time  

Science.gov (United States)

In the present paper, we derive phase equations for dynamical equations describing spatio-temporal dynamics in non-locally distributed systems. In the case of the spatial modulation of a periodic pattern, the phase equation is derived by carring out a suitable spatial average. The resulting equation has a structure with a generalized form that includes the Cahn-Hilliard equation. We also find that the phase equation for an oscillatory medium has the structure of a generalized form of the Kuramoto-Sivashinsky equation, implying the possibility of a Benjamin-Feir-type instability.

Tsukamoto, N.; Fujisaka, H.; Ouchi, K.

2006-10-01

389

Derivation of phase dynamics in non-locally distributed systems with periodic structures in either space or time  

International Nuclear Information System (INIS)

In the present paper, we derive phase equations for dynamical equations describing spatio-temporal dynamics in non-locally distributed systems. In the case of the spatial modulation of a periodic pattern, the phase equation is derived by carring out a suitable spatial average. The resulting equation has a structure with a generalized form that includes the Cahn-Hilliard equation. We also find that the phase equation for an oscillatory medium has the structure of a generalized form of the Kuramoto-Sivashinsky equation, implying the possibility of a Benjamin-Feir-type instability. (author)

2006-01-01

390

Chaos in a Lotka-Volterra predator-prey system with periodically impulsive ratio-harvesting the prey and time delays  

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.

2007-01-01

391

Quasi-periodic propagation in time of some classical/quantum systems: Nielsen's conserved quantity and Floquet properties  

Energy Technology Data Exchange (ETDEWEB)

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.

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

392

Transmission line theory of collective plasma excitations in periodic two-dimensional electron systems: Finite plasmonic crystals and Tamm states  

Science.gov (United States)

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 steplike periodic changes of electron density, gate screening, or both. We show that in a periodically modulated 2DEG, a plasmonic crystal is formed, and we derive closed-form analytical expressions describing its energy band spectrum for both infinite and finite size crystals. Our results demonstrate a nonmonotonic dependence of the plasmonic band gap width on the electron density modulation. At so-called transparency points, where the plasmon propagates through the periodic 2DEG in a resonant manner, the plasmonic band gaps vanish. In semi-infinite plasmonic crystals, we demonstrate the formation of plasmonic Tamm states and analytically derive their energy dispersion and spatial localization. Finally, we present detailed numerical analysis of the plasmonic band structure of a finite four-period plasmonic crystal terminated either by an ohmic contact or by an infinite barrier on each side. We trace the evolution of the plasmonic band spectrum, including the Tamm states, with changing electron density modulation and analyze the boundary conditions necessary for formation of the Tamm states. We also analyze interaction between the Tamm states formed at the opposite edges of the short length plasmonic crystal. The validity of our theoretical approach was confirmed in experimental studies of plasmonic crystals in short, modulated plasmonic cavities [Dyer , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.109.126803 109, 126803 (2012)], which demonstrated excellent quantitative agreement between theory and experiment.

Aizin, Gregory R.; Dyer, Gregory C.

2012-12-01

393

Decay of MHD Turbulence before the Final Period for Four-point Correlation in a Rotating System  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study is to determine decay of magnetic field fluctuations in MHD turbulence for four-point correlation in a rotating system before the final period. Two, three and four point correlation equations have been obtained and the set of correlation equations is made determinate by neglecting the quintuple correlations in comparison to the third and fourth order correlation terms. The correlation equations are converted to spectral form by taking their Fourier-transforms. Finally, integrating the energy spectrum over all wave numbers. The energy decay of magnetic field fluctuations for four-point correlations in a rotating system is obtained and is shown graphically in the text.

M.A. Bkar Pk; M.S. Alam Sarker; M.A.K. Azad

2013-01-01

394

Rotational sliding contact dynamics in a non-linear cam-follower system as excited by a periodic motion  

Science.gov (United States)

The rotational sliding contact dynamics of a cam-follower system is investigated using a single degree-of-freedom system given a periodic motion by the cam rotating about a fixed pivot. This mechanical system includes kinematic, dry friction, and contact non-linearities (loss of contact, non-linear contact stiffness, and non-linear damping) as it operates in both sliding contact and no-contact regimes. The Hertzian contact theory is used to calculate the contact stiffness under both line and point contacts. The non-linear formulation is numerically solved to calculate the dynamic motions and forces in time and frequency domains. Alternate damping formulations, including combined viscous-impact damping models, are assessed under impacting conditions, and the results are successfully compared with experimental results as available in the literature. The applicability of the coefficient of restitution model is critically analyzed. The friction and contact non-linearities of the system are investigated in the sliding contact regime. Finally, the kinematic non-linearity is studied in comparison with a linearized model.

Sundar, Sriram; Dreyer, Jason T.; Singh, Rajendra

2013-09-01

395

Electricity and heat system development scenarios integrated in the energy system sustainable development in Romania in the period 2005 - 2025  

International Nuclear Information System (INIS)

After 50 years of centralized economy, since 1989, Romania faces many challenges related to the internal conditions and to the new trends in energy markets over the world as: the existing low efficiency and availability, fast structural changes; the decentralization and privatization of the energy sector with new structures and entities; integration in EU and NATO structures. At present, with transition from the national vertical integrated monopolies to an open market, the determination of the global optimum development scenario of the power and heat sector becomes more important in order to find the policy which can lead the own strategies of different companies involved on market to a sustainable development of the society. The paper presents four long term development scenarios of the electricity and heat sector quantified from different points of view: technical, economical, environmental, social criteria, security of supply, risk diminishing etc and it continues by determining the long term global optimum development scenario integrated in the sustainable energy system. (authors)

2004-01-01

396

Periodic Table  

Science.gov (United States)

Using the Macromedia Shockwave Player, this American Chemical Society website offers three interactive periodic tables. Students can find the basic data on each element including its atomic radius, stable isotopes, melting point, and density in the first periodic table tab. The website identifies different elemental groups by color. Users can view the electron configuration by selecting elements on the periodic table in the second tab. The last tab offers plots of the elements' electronegativity, ionization energy, and other properties.

2007-05-04

397

Few period quasisymmetric stellarators  

Energy Technology Data Exchange (ETDEWEB)

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.

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

398

System and method for implementing periodic early discard in on-chip buffer memories of network elements  

Energy Technology Data Exchange (ETDEWEB)

An advance is made over the prior art in accordance with the principles of the present invention that is directed to a new approach for a system and method for a buffer management scheme called Periodic Early Discard (PED). The invention builds on the observation that, in presence of TCP traffic, the length of a queue can be stabilized by selection of an appropriate frequency for packet dropping. For any combination of number of TCP connections and distribution of the respective RTT values, there exists an ideal packet drop frequency that prevents the queue from over-flowing or under-flowing. While the value of the ideal packet drop frequency may quickly change over time and is sensitive to the series of TCP connections affected by past packet losses, and most of all is impossible to compute inline, it is possible to approximate it with a margin of error that allows keeping the queue occupancy within a pre-defined range for extended periods of time. The PED scheme aims at tracking the (unknown) ideal packet drop frequency, adjusting the approximated value based on the evolution of the queue occupancy, with corrections of the approximated packet drop frequency that occur at a timescale that is comparable to the aggregate time constant of the set of TCP connections that traverse the queue.

Francini, Andrea

2013-05-14

399

A system for generating long streamflow records for study of floods of long return period: Phase 2  

International Nuclear Information System (INIS)

Knowledge of the return periods of large floods is required to make risk analyses for nuclear power plants subject to flooding from rivers. The system reported here combined the stochastic simulation of hourly rainfall data and daily pan evaporation data with the deterministic simulation of streamflow by using the synthetic rainfall and evaporation data as input to a calibrated rainfall runoff model. The sequence of annual maximum flood peaks from a synthetic record of 10,000 years or more was then analyzed to obtain estimates of flood frequency. The reasonableness of the flood frequency results must be evaluated on the degree of mimicry of the key characteristics of the observed rainfall data and the ability of the rainfall-runoff model to mimic the observed flood frequency during the calibration period. On this basis, the flood frequency results appeared to be a reasonable extrapolation of the data used in defining the model parameters. There is a need to develop regional parameters for the stochastic models and to conduct research on the relationship between the stochastic structure of rainfall and stochastic structure of flood frequency. The methodology is applicable, assuming a highly skilled analyst, to watersheds similar to those already tested

1989-01-01

400

THE FIRST PHOTOMETRIC STUDY AND ORBITAL SOLUTION/PERIOD ANALYSIS OF THE MISCLASSIFIED BINARY SYSTEM V380 CAS  

International Nuclear Information System (INIS)

[en] We present the first multicolor CCD photometry for the eclipsing binary V380 Cassiopeia (V380 Cas) observed on 34 nights in 2009 and 2010 at the University of Patras Observatory. The PHOEBE program based on the Wilson-Devinney algorithm was used to analyze the first complete BVRc Ic light curves. It was found that V380 Cas was misclassified and it is a well-detached system consisting of two main-sequence stars. A range of solutions found to give satisfactory fits to the observations is also investigated. The first orbital solution based on the photometric mass ratio q = 1.08 of almost equal temperatures and masses and orbital inclination of i = 86.057 was obtained. In addition, based on all available times of light minima, including 12 new ones, a new orbital period of P = 2.714539884 days is given.

2012-01-01

 
 
 
 
401

THE FIRST PHOTOMETRIC STUDY AND ORBITAL SOLUTION/PERIOD ANALYSIS OF THE MISCLASSIFIED BINARY SYSTEM V380 CAS  

Energy Technology Data Exchange (ETDEWEB)

We present the first multicolor CCD photometry for the eclipsing binary V380 Cassiopeia (V380 Cas) observed on 34 nights in 2009 and 2010 at the University of Patras Observatory. The PHOEBE program based on the Wilson-Devinney algorithm was used to analyze the first complete BVR{sub c} I{sub c} light curves. It was found that V380 Cas was misclassified and it is a well-detached system consisting of two main-sequence stars. A range of solutions found to give satisfactory fits to the observations is also investigated. The first orbital solution based on the photometric mass ratio q = 1.08 of almost equal temperatures and masses and orbital inclination of i = 86.{sup 0}57 was obtained. In addition, based on all available times of light minima, including 12 new ones, a new orbital period of P = 2.714539884 days is given.

Christopoulou, P.-E.; Papageorgiou, A. [Department of Physics, University of Patras, 26500 Patra (Greece); Kleidis, S. [Helliniki Astronomiki Enosi, Athens (Greece); Tsantilas, S. [Department of Astrophysics, Astronomy and Mechanics, Faculty of Physics, Athens University, Panepistimiopolis, Zografos 15784, Athens (Greece)

2012-02-15

402

Periodic Review Probabilistic Multi-Item Inventory System with Zero Lead Time under Constraint and Varying Holding Cost  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: This study treats the probabilistic safety stock n-items inventory system having varying holding cost and zero lead-time subject to linear constraint. Approach: The expected total cost is composed of three components: the average purchase cost; the expected order cost and the expected holding cost. Results: The policy variables for this model are the number of periods N*r and the optimal maximum inventory level Q*mr and the minimum expected total cost. Conclusion/Recommendations: We can obtain the optimal values of these policy variables by using the geometric programming approach. A special case is deduced and an illustrative numerical example is added.

Naglaa H. El-Sodany

2011-01-01

403

Ab initio analytical infrared intensities for periodic systems through a coupled perturbed Hartree-Fock/Kohn-Sham method.  

UK PubMed Central (United Kingdom)

A fully analytical method for calculating Born charges and, hence, infrared intensities of periodic systems, is formulated and implemented in the CRYSTAL program, which uses a local gaussian type basis set. Our efficient formalism combines integral gradients with first-order coupled perturbed Hartree-Fock/Kohn Sham electronic response to an electric field. It avoids numerical differentiation with respect to wave vectors, as in some Berry phase approaches, and with respect to atomic coordinates. No perturbation equations for the atomic displacements need to be solved. Several tests are carried out to verify numerical stability, consistency in one, two, and three dimensions, and applicability to large unit cells. Future extensions to piezoelectricity and Raman intensities are noted.

Maschio L; Kirtman B; Orlando R; Rèrat M

2012-11-01

404

Ab initio analytical infrared intensities for periodic systems through a coupled perturbed Hartree-Fock/Kohn-Sham method.  

Science.gov (United States)

A fully analytical method for calculating Born charges and, hence, infrared intensities of periodic systems, is formulated and implemented in the CRYSTAL program, which uses a local gaussian type basis set. Our efficient formalism combines integral gradients with first-order coupled perturbed Hartree-Fock/Kohn Sham electronic response to an electric field. It avoids numerical differentiation with respect to wave vectors, as in some Berry phase approaches, and with respect to atomic coordinates. No perturbation equations for the atomic displacements need to be solved. Several tests are carried out to verify numerical stability, consistency in one, two, and three dimensions, and applicability to large unit cells. Future extensions to piezoelectricity and Raman intensities are noted. PMID:23205987

Maschio, Lorenzo; Kirtman, Bernard; Orlando, Roberto; Rèrat, Michel

2012-11-28

405

Searches for periodic neutrino emission from binary systems with 22 and 40 strings of IceCube  

CERN Multimedia

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...

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

406

On Late-Qing Scholars’ Understanding and Responding to Western Learning Classification System through Classification System for Translation Bibliography of the Late-Qing Period  

Directory of Open Access Journals (Sweden)

Full Text Available Modern science and Western thoughts were brought to China while missionaries arrived in the late 16th century. Learning Western Learning through translated books was the only manner that helps 19thcentury Chinese to build a strong and prosperous country. A number of translation bibliography specifically designed for translated books were invented as the demand for Western Learning and the number of translated books increased. These bibliographies were mainly developed by elite Chinese scholar, and they also found that traditional four-branch classification system could not cover Western Learning appropriately; this fact complicated classification systems for translation bibliography because scholars held different attitudes toward Western Learning. This paper analyzes the reformation of Chinese classification system in late-Qing by discussing the development of classification system for translation bibliography in that period, it also seeks to point out that this reformation helps people to conduct further research on the history of late-Qing books.

Chien-Yu Kuo

2012-01-01

407

Global well-posedness and non-linear stability of periodic travelling waves solutions for a Schr\\"odinger-Benjamin-Ono system  

CERN Multimedia

The objective of this paper is two-fold: firstly, we develop a local and global (in time) well-posedness theory of a system describing the motion of two fluids with different densities under capillary-gravity waves in a deep water flow (namely, a Schr\\"odinger-Benjamin-Ono system) for \\emph{low-regularity} initial data in both periodic and continuous cases; secondly, a family of new periodic travelling waves for the Schr\\"odinger-Benjamin-Ono system is given: by fixing a minimal period we obtain, via the implicit function theorem, a smooth branch of periodic solutions bifurcating of the Jacobian elliptic function called {\\it dnoidal}, and, moreover, we prove that all these periodic travelling waves are nonlinearly stable by perturbations with the same wavelength.

Angulo, J; Pilod, D; Angulo, Jaime; Matheus, Carlos; Pilod, Didier

2007-01-01

408

[The influence of frequency and blockade of the autonomic nervous system on the functional behaviour of the human conduction system. Part B: Refractory periods (author's transl)].  

Science.gov (United States)

32 patients were studied by His-bundle-electrocardiogram and programmed atrial stimulation to examine to which extent frequency and autonomic tone participate in influencing the effective (ERP) and functional (FRP) refractory periods of the atrium and AV-node. The measurements were performed during three electrically induced atrial frequencies before and after intravenous injection of 1 mg Atropine (15 patients) and 0.4 mg Visken (17 patients). For the atrium, frequency dominates the blockade of both components of the autonomic nervous system in influencing both refractory periods. Increase in frequency shortens both ERP and FRP of the atriu. The blockade of parasympathicus and sympathicus does not significantly influence the changes in atrial ERP and FRP induced by atrial pacing. The AV-node responses most sensitive to both pacing induced cycle length shortening and blockade of the autonomic tone. Cycle length shortening prolongs the nodal ERP. the FRP is either shortened or prolonged. Blockade of the parasympathicus shortens both nodal ERP and FRP. Blockade of the sympathicus lengthens both parameters. This behaviour of both refractory periods in response to atrial pacing and blockade of the autonomic tone are discussed with respect to the "gate mechanism" in the conduction system. In the majority of patients blockade of the parasympathicus shifts the "gate" from the AV-node to the atrium. Blockade of the sympathicus has the opposite effect in some cases. PMID:65171

Runge, M; Luckmann, E; Narula, O S

409

XIX Mendeleev Congress on general and applied chemistry. Abstract book in 4 volumes. Volume 4. Chemistry aspects of modern energy and alternative energy resources. Chemistry of fossil and renewable hydrocarbon raw materials. Analytical chemistry: novel methods and devices for chemical research and analysis. Chemical education  

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 4 includes abstracts of oral and poster presentations and presentations of correspondent participants of the sections: Chemistry aspects of modern energy and alternative energy resources; Chemistry of fossil and renewable hydrocarbon raw materials; Analytical chemistry: novel methods and devices for chemical research and analysis; Chemical education, and author index

2011-01-01

410

Period Cramps  

Science.gov (United States)

... ago. She's learned to handle using pads and tampons, but the cramps are really bothering her. Sometimes ... THIS TOPIC Do Periods Ever End? Pads and Tampons How Do Pain Relievers Work? Five Things Girls ...

411

Problem Periods  

Science.gov (United States)

... times you have to change your pads or tampons. Answering these questions can help you figure out ... very heavy You suddenly feel sick after using tampons You bleed in between periods or with sex ( ...

412

Periodized wavelets  

Energy Technology Data Exchange (ETDEWEB)

The properties of periodized Daubechies wavelets on [0,1] are detailed and contrasted against their counterparts which form a basis for L{sup 2}(R). Numerical examples illustrate the analytical estimates for convergence and demonstrate by comparison with Fourier spectral methods the superiority of wavelet projection methods for approximations. The analytical solution to inner products of periodized wavelets and their derivatives, which are known as connection coefficients, is presented, and several tabulated values are included.

Schlossnagle, G. [Johns Hopkins Univ., Baltimore, MD (United States); Restrepo, J.M.; Leaf, G.K. [Argonne National Lab., IL (United States). Mathematics and Computer Science Division

1993-12-01

413

Diurnal Effects of Periodic Litter Change on Egg Production and Physical Qualities in a Deep Litter System  

Directory of Open Access Journals (Sweden)

Full Text Available Five hundred and forty Lohmann hybrid point of lay birds aged 22 weeks were used to study the effect of periodic litter change on egg production and physical qualities. The birds were divided into 3 treatment groups consisting of 180 birds. Each treatment group was further replicated 3 times, made of 60 birds per replicate. Each treatment was allotted to three treatment periods of egg collection identified as T1 (morning 0700-1100 hrs). T2 (afternoon 1100-1400000 hrs) and T3 (evening 1400-1700 hrs) in a Completely Randomized Design (CRD). The birds were provided with water and feed ad-libitum. Litter was changed every 12 weeks and the experiment lasted for forty-eight weeks. The results of the climatic environmental conditions of the experimental site i.e. the ambient temperature, rectal temperature, relative humidity and wind velocity showed non significant difference (p>0.05) between T1 morning and T3 evening values but they differed significantly (p>0.05) from T2 afternoon values. The hen day egg production (61.15±0.87), hen housed egg production (59.04±0.91) and laying house mortality (4.69±0.43) for T1 morning were similar (p>0.05) to T3 evening hen day egg production (64.76±0.95), hen house egg production (61.41±0.73) and laying house mortality (3.91±0.42). Feed consumption, feed conversion and weight of the birds did not show any significant difference (p>0.05) between the treatment groups. The albumen weight, Haugh unit, egg length and width followed the same pattern as in the hen day egg production. The egg weight, yolk weight, shell weight and thickness in T1 morning, T2 afternoon and T3 evening did not differ (p>0.05) significantly between treatment groups. The pees-wees, cracked eggs and small-sized eggs were similar (p>0.05) in T1 morning and T3 evening period but significantly lower (p2 afternoon values. The large sized and extra large eggs were similar in T1 and T3 but significantly (p2 values. The results of this study show that litter change in a deep-litter system should be in the morning or evening must have finished egg laying for the day and when the ambient temperature must have fallen and is within the thermoneutrality zone between 12.8°C and 26°C.

E.C. Ndubuisi; F.C. Iheukwumere; P.E. Etusim

2008-01-01

414

Hymenolepis diminuta: experimental studies on the antioxidant system with short and long term infection periods in the rats.  

Science.gov (United States)

Many helminths cause long-lasting infections, living for several years in mammalian hosts reflecting a well balanced coexistence between host and parasite. There are many possible explanations as to how they can survive for lengthy periods. One possibility is their antioxidant systems, which can serve as defence mechanisms against host-generated oxygen radicals. Therefore, the aim of this experimental study was to examine the antioxidant system in Hymenolepisdiminuta during short (1.5 months young tapeworms) and long (1.5 years old tapeworms) term infection in the rat small intestine. The strobilae of H. diminuta tapeworms (14 young and three old) were divided into three pieces: the anterior part, containing the genital primordiae in the immature segments; the medial part, containing the early uterus in the mature, hermaphroditic proglottids and the terminal part with the mature gravid uterus in the gravid segments. Supernatants of these fragments were used for determination of markers of oxidative stress: concentration of thiobarbiturate reactive substances (TBARS) and of reduced glutathione (GSH), and the activity of antioxidant enzymes: superoxide dismutase (SOD1 and SOD2), catalase (CAT), glutathione peroxidases (GSHPxs), glutathione transferase (GST) and glutathione reductase (GSHR). The results indicated changes in levels of oxidative stress markers and antioxidant enzyme activity in both the young and old forms of H. diminuta. Relatively high activity of SOD (particularly in the anterior part of young tapeworms) was observed, as was increased activity of total GSHPx and a relatively high concentration of GSH in all parts of the tapeworms. These are caused by exposure to increased amount of ROS, which are produced during the inflammatory state. Due to the high activity of antioxidant enzymes, the anterior section of young and old tapeworms is equipped with a very effective antioxidant system. Old organisms also effectively resist oxidative stress due to reduced levels of lipid peroxidation and the high activity of GST, all of which suggest good adaptation to the hostile environment in the host's intestine. PMID:21782814

Skrzycki, Micha?; Majewska, Monika; Podsiad, Ma?gorzata; Czeczot, Hanna; Salamatin, Rus?an; Twarowska, Joanna; Grytner-Zi?cina, Barbara

2011-07-20

415

Hymenolepis diminuta: experimental studies on the antioxidant system with short and long term infection periods in the rats.  

UK PubMed Central (United Kingdom)

Many helminths cause long-lasting infections, living for several years in mammalian hosts reflecting a well balanced coexistence between host and parasite. There are many possible explanations as to how they can survive for lengthy periods. One possibility is their antioxidant systems, which can serve as defence mechanisms against host-generated oxygen radicals. Therefore, the aim of this experimental study was to examine the antioxidant system in Hymenolepisdiminuta during short (1.5 months young tapeworms) and long (1.5 years old tapeworms) term infection in the rat small intestine. The strobilae of H. diminuta tapeworms (14 young and three old) were divided into three pieces: the anterior part, containing the genital primordiae in the immature segments; the medial part, containing the early uterus in the mature, hermaphroditic proglottids and the terminal part with the mature gravid uterus in the gravid segments. Supernatants of these fragments were used for determination of markers of oxidative stress: concentration of thiobarbiturate reactive substances (TBARS) and of reduced glutathione (GSH), and the activity of antioxidant enzymes: superoxide dismutase (SOD1 and SOD2), catalase (CAT), glutathione peroxidases (GSHPxs), glutathione transferase (GST) and glutathione reductase (GSHR). The results indicated changes in levels of oxidative stress markers and antioxidant enzyme activity in both the young and old forms of H. diminuta. Relatively high activity of SOD (particularly in the anterior part of young tapeworms) was observed, as was increased activity of total GSHPx and a relatively high concentration of GSH in all parts of the tapeworms. These are caused by exposure to increased amount of ROS, which are produced during the inflammatory state. Due to the high activity of antioxidant enzymes, the anterior section of young and old tapeworms is equipped with a very effective antioxidant system. Old organisms also effectively resist oxidative stress due to reduced levels of lipid peroxidation and the high activity of GST, all of which suggest good adaptation to the hostile environment in the host's intestine.

Skrzycki M; Majewska M; Podsiad M; Czeczot H; Salamatin R; Twarowska J; Grytner-Zi?cina B

2011-10-01

416

Existence of Periodic Solutions for a Delayed Ratio-Dependent Three-Species Predator-Prey Diffusion System on Time Scales  

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Full Text Available This paper investigates the existence of periodic solutions of a ratio-dependent predator-prey diffusion system with Michaelis-Menten functional responses and time delays in a two-patch environment on time scales. By using a continuation theorem based on coincidence degree theory, we obtain suffcient criteria for the existence of periodic solutions for the system. Moreover, when the time scale 𝕋 is chosen as ? or ?, the existence of the periodic solutions of the corresponding continuous and discrete models follows. Therefore, the methods are unified to provide the existence of the desired solutions for the continuous differential equations and discrete difference equations.

Zhenjie Liu

2009-01-01

417

[Dynamics of parameters of systemic inflammation and hemocoagulation in early postoperative period in patients with heart valve prostheses].  

UK PubMed Central (United Kingdom)

In 42 patients with rheumatic heart defects before implantation of mechanical valves and on days 5 and 20 after surgery we measured parameters of hemostasis, levels of proinflammatory cytokines (interleukin 6 [IL-6], tumor necrosis factor- [TNF-] and C-reactive protein [CRP]) as well as activity of enzymes (alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, creatine phosphokinase and its MB fraction). On day 5 after surgery we revealed substantial elevation of IL-6, TNF-, and CRP levels, increase of activity of the studied enzymes, contents of fibrinogen and soluble fibrin monomer complexes (SFMC), and to the contrary lowering of antithrombin III level and decrease of number of platelets. On day 20 IL-6 and TNF- levels remained significantly elevated compared to preoperative values. Concentrations of enzymes and parameters of hemostasis returned to baseline values while content of SFMC remained significantly decreased. In early postoperative period levels of IL-6 and TNF- significantly correlated with that of SFMC and platelet count what reflected interrelation ship of processes of inflammation and coagulation. Severity of systemic inflammatory reaction in patients with implanted prosthetic valves influenced optimal doses of warfarin.

Iskenderov BG; Vasil'ev DA

2013-01-01

418

Light Microscopic Evaluation of Cardio-vasculare System in Alloksan-induced Diabetic Rats in Acute Period  

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Full Text Available Diabetic cardiomyopathy is one of the chronic complication of diabetes and acute effects of diabetes on heart and aorta is not clear. We aimed to determine acute effects of diabetes on cardio-vasculare system with light microscopy. We used 20 Spraque-Dawley rats and applied 150 mg/kg alloxan, intraperitoneally for inducing diabetes and 1 ml SF in control group. After 24 hours, venous blood samples were measured. Blood glucose levels higher than 250 mg/dl were accepted as DM and treated with 4 IU/d human insülin. After 7 days rats were sacrified under ketamin anaesthesia. Heart and aorta were fixed in 10 % buffered formalin. The sectiones were embedded in paraffin and were serially sectioned at 5 ?m thickness, then stained with Hematoxyline-Eosine (H&E) and Heidenhein’s Azan modification.There was no histopathological changes in cardiac muscle cells in control group. But there was a heterogen appearance in cardiac muscle cells and we determined some hydropic degenerations in some of the cardiac muscle cells and a minimal fibrosis in perivasculare and interstitial area in diabetic group. All histological stratums of aorta were seen normally in control group. In diabetic group, there was a clear anisostosis in smooth muscle cells and decreased in nucleus of smooth muscle cells in tunica media. We concluted that DM is caused degeneration and fibrosis in cardiac muscle cells and effective on smooth muscle cells in aorta in acute period.

Selen Bahçeci; Naime Canoruç; Yusuf Nergiz; Sevda Söker; Deniz Gökalp; Mehmet Erdem Akbal?k; Yekbun Tut?i

2007-01-01

419

Ti-chabazite as a model system of Ti(IV) in Ti-zeolites: A periodic approach  

Science.gov (United States)

For the first time, full ab initio periodic calculations on a Ti-chabazite with a very low content of Ti (Ti/Si=1/11) were done. The simulated crystal is less computationally demanding and it is similar to the real titanosilicates microporous materials such as TS-1 or Ti-?, where the Ti/Si is lower than 1/30, and hence it can be used as a model system. The geometric and energetic features of the interaction of Ti-CHA with NH3, H2O, H2CO, and CH3CN were studied, principally at the Hartree-Fock level. Bare Ti-CHA and its NH3, H2O, H2CO, and CH3CN complexes were fully optimized at Hartree-Fock level with an upgraded version of the CRYSTAL code [Chem. Phys. Lett. 348, 131 (2001)] and such optimized structures were employed to calculate BEc (binding energy corrected for the basis set superposition error) at the Hartree-Fock and B3-LYP levels.

Damin, Alessandro; Bordiga, Silvia; Zecchina, Adriano; Doll, Klaus; Lamberti, Carlo

2003-06-01

420

Morphometric analysis of diffuse endocrine system's components in esoph-agogastroduodenal zone in different periods after cholecystectomy  

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Full Text Available The examination of morphofunctional features of esophagus, stomach, and duodenum as well as the role of diffusive endocrine system's cells in development of esophagogastroduodenal zone in patients without gallbladder is the purpose of the study. 80 patients with various periods after cholecystectomy and 72 patients with cholelithiasis were examined. Endo-scopic, histological and immuno-histochemical studies were carried out against all examined patients. The amount of epitheliocytes producing motilin (EC2), glucagon (L), and pancreatic polypeptide (PP) in duodenum were determined using antibodies sets. Esophagitis, atrophic- and reflux-gastritis, duodenal reflux are positively rather frequently met, atrophy and dysplasia of gastric mucous membrane increase in patients without gallbladder during the time after cholecystectomy. Hypoplasia of epithelial cells producing motilin, glucagon and pancreatic polipetide progresses. The development of duodenal and gastroesophagial reflux is associated with hypoplasia of epithelicytes producing motilin; the development of erosive changes is connected with hypoplasia of L and PP cells; the development of atrophic changes is closely related with hypoplasia of all studied cell types. The decrease of hormone producing epythelicytes promotes initiation and persistence of morphofunctional changes in esophagogastricduodenal zone. And this in turn can serve as additional diagnostic and prognostic criterion.

Graushkina E.V.; Kozlova I.V.; Fedorov V.E.

2009-01-01

 
 
 
 
421

Bifurcations of periodic trajectories in non-integrable Hamiltonian systems with two degrees of freedom: Numerical and analytical results  

Energy Technology Data Exchange (ETDEWEB)

Numerical and analytical studies of the types of period n-upling bifurcations undergone by classical periodic trajectories of non-integrable Hamiltonians with two degrees of freedom are made. The Hamiltonians studied possess time reversal and reflection symmetries and we found that these symmetries give rise to additional types of period n-upling bifurcations. The analytical study explains most of the numerically observed birfucations. copyright 1987 Academic Press, Inc.

de Aguiar, M.A.M.; Malta, C.P.; Baranger, M.; Davies, K.T.R.

1987-12-01

422

Advanced development of particle beam probe diagnostic systems: Technical progress report covering the period October 1, 1985-August 31, 1987  

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

1987-01-01

423

Periodic Boehmians  

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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.

Dennis Nemzer

1989-01-01

424

Water erosion during a 17-year period under two crop rotations in four soil management systems on a Southbrazilian Inceptisol  

Science.gov (United States)

Soil erosion still remains a persistent issue in the world, and this in spite of the efforts to ameliorate soil management systems taken into account the point of view of environmental protection against soil losses. In South Brazil water erosion is mainly associated to rainfall events with a great volume and high intensity, which are more or less evenly distributed all over the year. Nowadays, direct drilling is the most widely soil management system used for the main crops of the region. However, some crops still are grown on conventionally tilled soils, which means mainly ploughing and harrowing and less frequently chisel ploughing. In Lages-Santa Catarina State, Brazil, a plot experiment under natural rain was started in 1992 on an Inceptisol with the aim of quantifying soil and water losses. Treatments included bare and vegetated plots. The crop succession was: oats (Avena strigosa), soybean (Glycine max), vetch (Vicia sativa), maize (Zea mays), fodder radish (Raphanus sativus) and beans (Phaseolus vulgaris). Soil tillage systems investigated in this study were: i) conventional tillage (CT), ii) reduced tillage (MT), iii) no tillage (NT) under crop rotation and iv) conventional tillage on bare soil (BS). Treatments CT and BS involved ploughing plus twice harrowing, whereas MT involved chisel ploughing plus harrowing. Rainfall erosivity from January 1 1992 to December 31 2009 was calculated. Soil losses from the BS treatment along the 17 year study period were higher than 1200 Mg ha-1. Crop cover significantly reduced erosion, so that under some crops soil losses in the CT treatment were 80% lower than in the BS treatment. In turn soil losses in the MT treatment, where tillage was performed by chiselling and harrowing, were on average about 50% lower than in the CT treatment. No tillage was the most efficient soil management system in reducing soil erosion, so that soil losses in the NT treatment were about 98% lower than in the BS treatment. The three vegetated treatments, CT, MT and NT showed a lower efficiency in reducing water losses than soil losses. Water losses by runoff during a number of events were of the same order of magnitude for all the management systems studied here; which was mainly true when the volume of rainfall was high and the lag between successive events was small. In general, soil losses in the autumn-winter seasons were lower than under the spring-summer seasons. Soil losses showed a positive correlation with rainfall erosivity. However, the degree of dependence between these two variables decreased as the efficiency of soil management in controlling soil erosion increased. The large soil and water losses in the BS and CT treatments suggest that there is a need to implement soil conservation measures in the study region. In this context soil conservation would take advantage from soil cover by previous crop residue as well as from terrace building. Acknowledgement: This work was partly supported by Spanish Ministry of Education (Project CGL2005-08219-C02).

Bertol, Ildegardis; Vidal Vázquez, Eva; Paz Ferreiro, Jorge

2010-05-01

425

Rhythmic profiles of cell cycle and circadian clock gene transcripts in mice: a possible association between two periodic systems.  

UK PubMed Central (United Kingdom)

The circadian system shapes the rhythms of most biological functions. The regulation of the cell cycle by a circadian clock was suggested to operate via stages S, G2 and G2/M. This study investigated a possible time link at stages G1 and G1/S as well. The daily expression profiles of cell cycle markers (Ccnd1, Ccne1 and Pcna) and circadian clock genes (Per2 and Clock) were monitored in liver and esophagus (low and high proliferation index, respectively) of BALB/c mice. Locomotor activity displayed a 24 h rhythm, establishing the circadian organization of the suprachiasmatic nucleus. In the liver, the mRNA level of Per2 and Clock fitted the circadian rhythm with a 7.5 h shift. This temporal pattern suggests that the liver harbors a functional circadian clock. The rhythm of the analyzed cell cycle genes, however, was of low significance fitness and showed an opposite peak time between Pcna and Clock. These results indicate a weak regulatory role of the circadian clock. In the esophagus, the rhythms of Clock and Per2 mRNA had a similar peak time and non-circadian periods. These results suggest either that the esophagus does not harbor a functional circadian apparatus or that the phenotypes stem from differences in phase and amplitude of the rhythms of its various cell types. The similarity in the rhythm parameters of Clock, Ccne1 and Pcna transcripts questions the control of the circadian clock on the cell cycle along the G1 and G1/S stages. Yet the G1/S transition may play a role in modulating the local clock of proliferating tissues.

Weigl Y; Ashkenazi IE; Peleg L

2013-06-01

426

Periodicities in the high-mass X-ray binary system RX J0146.9+6121/LS I+61 235  

CERN Multimedia

The high-mass X-ray binary RX J0146.9+6121, with optical counterpart LS I+61 235 (V831 Cas), is an intriguing system on the outskirts of the open cluster NGC 663. It contains the slowest X-ray pulsar known with a pulse period of around 1400s and, primarily from the study of variation in the emission line profile of H alpha, it is known to have a Be decretion disk with a one-armed density wave period of approximately 1240d. Here we present the results of an extensive photometric campaign, supplemented with optical spectroscopy, aimed at measuring short time-scale periodicities. We find three significant periodicities in the photometric data at, in order of statistical significance, 0.34d, 0.67d and 0.10d. We give arguments to support the interpretation that the 0.34d and 0.10d periods could be due to stellar oscillations of the B type primary star and that the 0.67d period is the spin period of the Be star with a spin axis inclination of 23 +10 -8 degrees. We measured a systemic velocity of -37.0 +- 4.3 km/s c...

Sarty, Gordon E; Huziak, Richard; Catalan, Lionel J J; Luciuk, Diane; Crawford, Timothy