WorldWideScience
 
 
1

New regularities in correlations of chemical properties of elements of Mendeleev's periodic system  

International Nuclear Information System (INIS)

Regularities in change of chemical properties of elements depending on their position in Mendeleev's periodic system are considered. Results of investigating compositions in which elements (astatine, technetium et al.) manifest unusual valence are presented. New data on chemical properties of rare earths and actinides are generalized. Similarity of properties of the first half lanthanide and the second half actinide elements is substantiated. On the basis of predictions of atomic electron structure of the end actinide series and the following transactinide elements their possible valent states are discussed

1986-02-01

2

Energetics of complex uranium halides in the light of D. I. Mendeleev Periodic System  

Energy Technology Data Exchange (ETDEWEB)

Thermochemical data for complex uranium halides are considered using published materials in the light of the periodic element system. The enthalpy list is compiled for complex halide production mutually correlated on the basis of the common system of the key thermochemical data. Using the proposed method the lattice energies, enthalpies of complex anion production, average binding energies and coordination enthalpies are calculated, the regularities of their variation in the complex halide series are discussed. The calculation results are compared with experimentally determined enthalpies of complex anion production.

Chirkst, D.Eh.

1982-01-01

3

On the molybdates and tungstates of the second group elements of D.I. Mendeleev periodic system  

International Nuclear Information System (INIS)

On the basis of the literature data analysed are the optimum conditions for preparation, thermodynamic and structural characteristics of orto- and oxymolybdates and tungstates of elements of the 2nd group of the periodic system. The regularities of changes of compound properties depending on the geometrical characteristics of cations are found out. The conditions of aquopolycompound preparation in 0.1 M solutions at 25+-0.1 deg C are studied. The intervals of thermal stability of para- and meta-salts are established. Considered is the character of OH- groups introduction in the composition of compounds, and shown is the coordination between the anions of aquopolymolybdates (tungstates) of the elements of the 2nd group of the periodic system and the generally adopted models for para- and metaanions

1979-01-01

4

Additional Explanations to "Upper Limit in Mendeleev’s Periodic Table - Element No.155". A Story How the Problem was Resolved  

Directory of Open Access Journals (Sweden)

Full Text Available This paper gives a survey for the methods how a possible upper limit in Mendeleev's Periodic Table can be found. It is show, only the method of hyperbolas leads to exact answering this question.

Khazan A.

2009-07-01

5

From the Mendeleev periodic table to particle physics and back to the periodic table  

CERN Document Server

We briefly describe in this paper the passage from Mendeleev's chemistry (1869) to atomic physics (in the 1900's), nuclear physics (in the 1932's) and particle physics (from 1953 to 2006). We show how the consideration of symmetries, largely used in physics since the end of the 1920's, gave rise to a new format of the periodic table in the 1970's. More specifically, this paper is concerned with the application of the group SO(4,2)xSU(2) to the periodic table of chemical elements. It is shown how the Madelung rule of the atomic shell model can be used for setting up a periodic table that can be further rationalized via the group SO(4,2)xSU(2) and some of its subgroups. Qualitative results are obtained from this nonstandard table.

Kibler, M R

2006-01-01

6

Evidence for Energy Regularity in the Mendeleev Periodic Table  

CERN Document Server

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

7

On character of dependence of heat capacity of simple bodies on number of element in the Mendeleev periodic system at different temperatures  

International Nuclear Information System (INIS)

The dependence of atomic heat capacity of simple bo--dies on the atomic numbers of the elements in the Periodic Table has been considered at temperatures above and below the Debye characteristic temperature. In both cases considerable deviation from the Dulong and Petit rule are observed, and the dependence Csub(p) approximately f(Z) is periodic. The periodicity character is different at high and low temperatures. This may be due to the differences in dependence of harmonic and anharmonic components of heat capacity which manifest themselves below and above the Debye temperature, respectively. The role of the chemical bond character is noted in the processes of alteration of heat capacity components within the corresponding temperature ranges

1978-05-01

8

On interrelation of phase diagrams of binary systems. f-d elements of Mendeleev's table  

International Nuclear Information System (INIS)

Considered are phases of state diagrams of REE and actinides with d-elements of Mendeleev's table, and the system of their interaction is built. The found regularities permit to forecast the existence of new unknown phases in the investigated alloys

1979-09-01

9

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

International Nuclear Information System (INIS)

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

10

Comments on Mendeleev's table  

International Nuclear Information System (INIS)

The spectroscopic study in a balloon carried out by Mendeleev during a solar eclipse is suggested as the first 'astronautical' experiment to find new elements. Future experiments are alluded to at the end. Intervals between elements in the early versions of the Periodic Table are reviewed and in particular, the relation to the dependency of the order in which shells are filled on (n + l). The regular sequences in non-relativistic treatments are broken up when the relativistic orbitals are used to find the ground state of heavy atoms. No rule of ordering has been developed to date for relativistic atoms. (author)

1972-09-08

11

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

2007-09-23

12

Reconstruction of late Quaternary sedimentary environments at the southern Mendeleev Ridge (Arctic Ocean)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The late Pleistocene history of the Arctic comprised cyclical changes in the extension of land-based ice sheets and sea-ice cover that affected sedimentary environments in the Arctic Ocean. This PhD thesis focuses on sediment records from the Mendeleev Ridge spanning the last 200 ka. Over this time period, variable sedimentation patterns were described and possible implications for reconstruction of glacial/interglacial paleoenvironments were provided. One of the main goals of this study was ...

Bazhenova, Evgenia

2012-01-01

13

On Periodic Dynamical Systems  

CERN Document Server

In this paper, we investigate the existence and the global stability of periodic solution for dynamical systems with periodic interconnections, inputs and self-inhibitions. The model is very general, the conditions are quite weak and the results obtained are universal.

Lu, Wenlian; Lu, wenlian; Chen, Tianping

2004-01-01

14

The Periodic Table in Croatia  

Directory of Open Access Journals (Sweden)

Full Text Available The Croatian (Yugoslav Academy of Sciences and Arts was the first academy to elect D. I. Mendeleev as its honorary member (1882, whereas the periodic table of the elements has been taught regularly at the Zagreb University since 1888. The early interest of Croatian chemists in the periodic table should be attributed primarily to their pan-Slavic attitude, particularly as proof that Slavic people were able to produce "their own Newtons" (M. V. Lomonosov and D. I. Mendeleev. Such enthusiastic views, however, did not help in analyzing the contribution of Mendeleev and other scientists to the discovery and development of the periodic table of the elements.

Raos, N.

2011-12-01

15

Tectonic pattern of the Mendeleev Ridge and adjacent basins: results of joint analysis of potential fields and recent Russian seismic data  

Science.gov (United States)

The work was performed under Russian Federation State Geological mapping at a scale of 1:1 000 000 and UNCLOS programs. The study area is located between 76N-84N and 156E-168W and covers the Mendeleev Ridge, adjacent Podvodnikov, Mendeleev, Chukchi Basins and northern part of the East-Siberian Sea shelf. It is characterized by very poor magnetic and gravity data coverage. Majority of airborne magnetic and on-ice gravity surveys were carried out in the region about 40 years ago and have low spatial resolution and poor navigation. Seismic data collected earlier in the study area are presented by sparse lines of historical seismic reflection soundings and by results of deep seismic refraction and reflection observations along several geotransects. Hence, conclusions concerning tectonic structure and spatial relation of the Mendeleev Ridge with adjacent geological structures up to present day remain speculative. Joint analysis of recent seismic reflection and refraction data collected during Russian expeditions «Arctic-2011» and «Arctic-2012» with mentioned above geophysical information allowed to clarify the contours of geological structures in the study area and reveal some new peculiarities of their tectonic pattern. Particularly complex tectonic structure of the Mendeleev Ridge, changing from it's southern to the northern part and represented by two main systems of tectonic displacements is discovered. The first fault system comprises horsts/graben-bounding faults oriented preferably in N-S direction. The second system is presented by faults of NW-SE direction disturbing the first one. In the southern part of the Mendeleev Ridge such faults are the strike-slip faults with small horizontal displacements. Starting from the central part of the ridge and further to the north, displacements along strike-slip faults become progressively more pronounced and have sinistral character. In the northern part of the ridge a pull-apart structures are recognized which presumably correspond to the transitional shear zone between the Mendeleev and the Alpha ridges. Mentioned above features indicate that existed earlier as a single structure the Alpha-Mendeleev Ridge was exposed to transtension. As a result it was separated later by the shear zone on two ridges which moved from each other with forming the system of NW-SE left-lateral strike-slip (oblique-slip) faults. Some more details and speculations concerning the tectonic pattern of the Mendeleev Ridge and adjacent structures will be offered in presentation.

Chernykh, Andrey; Astafurova, Ekaterina; Korneva, Maria; Egorova, Alena; Redko, Anton; Glebovsky, Vladimir

2014-05-01

16

Proton magnetic resonance in hydrates of tungstates of 2-4th group elements of D.I. Mendeleev periodic system  

International Nuclear Information System (INIS)

By the methods of PMR and infrared-spectroscopy studied are the tungstate hydrates of Mg, Li, Cd, Al, Ge, In, Ti, Ln, Hf. The PMR spectra have been taken for air-dry and partly hydrated samples in the temperature range from 93 to 295 K. In tungstate hydrates of the 2nd and 4th groups found are the distorted moleculas of H2O with the intermolecular interproton distances different from 1.53 A, namely, increased up to 2.69 A and decreased to 1.38 A. Determined is the quantitative content of OH- groups and H2O moleculas, with different interproton distance. A formula content of the compounds studied is proposed. In tungstates of the 3d group the distorted moleculas are found only in compounds with H-/Me2O distortion is confirmed by the data of infrared spectr. The process of dehydration of distorted H2O moleculas is studied

1979-01-01

17

The final elements of the Mendeleev table  

International Nuclear Information System (INIS)

Over two centuries ago, chemical elements classification has witnessed several surprising variations, which we live approximately their last stages. Workers in this field are similar to runners who progressed actively at the beginning for few seconds. Then they should struggle thereafter to gain very few percentage of a second. Physicists have shown, over the past three years, unlimited patience and ingenuity towards the filling of the final empty spaces of Mendeleiev table, especially that created elements usually disappear after its formation in about a millisecond time period. Identification of new elements is similar to police investigation, and we find here that the family of strange behavior and accurately tracked one is the trans actinides family. This article illustrates the great moments of this investigation which recently has been achieved. 16 refs., 8 figs

1992-01-01

18

From the other oil field : Mendeleev, the West and the Russian oil industry  

Energy Technology Data Exchange (ETDEWEB)

This thesis examines whether Dmitrii Ivanovich Mendeleev, a Russian chemist, was open to Western ideas and capital in the Russian petroleum industry. Five of Mendeleev's business trips which took place between 1863 and 1886 were studied. They included trips to France, the United States and the Caucasus. Personal letters, diaries, and published articles were produced from each trip. This thesis looks at both published and unpublished archival documents to reveal much about the history of the Russian petroleum industry, its industrialists and Mendeleev's personality. The first chapter summarizes Mendeleev's important formative years before he began to work in the oil industry in 1863. His youthful travels around Europe, studies in Germany and personal inclinations made him a multilingual and cosmopolitan individual. The following 5 chapters examined Mendeleev's trips to study the industry, and an epilogue recounts his final years. It was concluded that contrary to Soviet teaching, Mendeleev was open to the West. His sole request was that Western ideas and capital help develop the Russian oil industry to produce large volumes of inexpensive kerosene for the Russian population.

Butorac, M.

2004-07-01

19

Glacial freshwater discharge events recorded by authigenic neodymium isotopes in sediments from the Mendeleev Ridge, western Arctic Ocean  

Science.gov (United States)

The freshwater budget of the Arctic Ocean is a key component governing the deep water formation in the North Atlantic and the global climate system. We analyzed the isotopic composition of neodymium (?Nd) in authigenic phases of marine sediments on the Mendeleev Ridge in the western Arctic Ocean spanning an estimated time interval from present to about 75 ka BP. This continuous record was used to reconstruct the ?Nd of the polar deep water (PDW) and changes in freshwater sources to the PDW through time. Three deviations in ?Nd from a long term average of -10.2 were identified at estimated 46-51, 35-39 and 13-21 ka BP. The estimated 46-51 ka BP event can be traced to bursting of ice-dammed lakes accompanying the collapse of the Barents-Kara Ice Sheet, which would have released radiogenic Nd to the eastern Arctic Ocean. The cyclonic surface circulation in the eastern Arctic Ocean must have been stronger than at present for the event to be recorded on the Mendeleev Ridge. For the 35-39 and 13-21 ka BP events, it is likely that the Laurentide Ice Sheet (LIS) supplied the unradiogenic freshwater. The configuration of the anticyclonic circulation in the western Arctic was probably similar to today or expanded eastward. Our simple mass balance calculations suggest that large amounts of freshwater were released but due to significant deep water formation within the Arctic Ocean, the effect on the formation of NADW was probably minor.

Jang, Kwangchul; Han, Yeongcheol; Huh, Youngsook; Nam, Seung-Il; Stein, Ruediger; Mackensen, Andreas; Matthiessen, Jens

2013-05-01

20

A Periodic Lotka-Volterra System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper periodic time-dependent Lotka-Volterra systems are considered. It is shown that such a system has positive periodic solutions. It is done without constructive conditions over the period and the parameters.

Tsvetkov, D.

1996-01-01

 
 
 
 
21

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

22

Positive periodic solutions of delayed periodic Lotka-Volterra systems  

Energy Technology Data Exchange (ETDEWEB)

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.

Lin Wei [Laboratory of Nonlinear Mathematics Science, Institute of Mathematics, Fudan University, Shanghai 200433 (China)]. E-mail: weilin@fudan.edu.cn; Chen Tianping [Laboratory of Nonlinear Mathematics Science, Institute of Mathematics, Fudan University, Shanghai 200433 (China)]. E-mail: tchen@fudan.edu.cn

2005-01-17

23

Asymptotic Behavior of a Periodic Diffusion System  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract We study the asymptotic behavior of the nonnegative solutions of a periodic reaction diffusion system. By obtaining a priori upper bound of the nonnegative periodic solutions of the corresponding periodic diffusion system, we establish the existence of the maximum periodic solution and the asymptotic boundedness of the nonnegative solutions of the initial boundary value problem.

Li Songsong

2010-01-01

24

False periods in complex chaotic systems  

CERN Multimedia

Astrophysical objects frequently exhibit some irregularities or complex behaviour in their light curves. We focus primarily on hot stars, where both radial and non-radial pulsations are observed. One of the primary research goals is to determine physical parameters of stellar pulsations by analyzing their light curves or spectra, focusing on periodic or quasiperiodic behaviour. We analyse the feasibility of classical methods for period searches in a nonlinear chaotic system, such as the R\\"ossler system, where a period does not exist at all. As an astrophysical application of the chaotic system, we utilize a simple model of stellar pulsation with two different sets of parameters corresponding to periodic and chaotic behaviour. For both models we create a synthetic signal, and then apply widely used methods for period finding, such as the phase dispersion method and periodograms. For comparison, a quasi-periodic signal is employed as well. The period analysis indicates periods even for the chaotic signal. Such...

Votruba, V; Kor?áková, D; Hroch, F

2009-01-01

25

Late Quaternary sediment deposition of core MA01 in the Mendeleev Ridge, the western Arctic Ocean: Preliminary results  

Science.gov (United States)

Late Quaternary deep marine sediments in the Arctic Ocean are characterized by brown layers intercalated with yellowish to olive gray layers (Poore et al., 1999; Polyak et al., 2004). Previous studies reported that the brown and gray layers were deposited during interglacial (or interstadial) and glacial (or stadial) periods, respectively. A 5.5-m long gravity core MA01 was obtained from the Mendeleev Ridge in the western Arctic Ocean by R/V Xue Long during scientific cruise CHINARE-V. Age (~450 ka) of core MA01 was tentatively estimated by correlation of brown layers with an adjacent core HLY0503-8JPC (Adler et al., 2009). A total of 22 brown layers characterized by low L* and b*, high Mn concentration, and abundant foraminifera were identified. Corresponding gray layers are characterized by high L* and b*, low Mn concentration, and few foraminiferal tests. Foraminifera abundance peaks are not well correlated to CaCO3 peaks which occurred with the coarse-grained (>0.063 mm) fractions (i.e., IRD) both in brown and gray layers. IRDs are transported presumably by sea ice for the deposition of brown layers and by iceberg for the deposition of gray layers (Polyak et al., 2004). A strong correlation coefficient (r2=0.89) between TOC content and C/N ratio indicates that the major source of organic matter is terrestrial. The good correlations of CaCO3 content to TOC (r2=0.56) and C/N ratio (r2=0.69) imply that IRDs contain detrital CaCO3 which mainly originated from the Canadian Arctic Archipelago. In addition, high kaolinite/chlorite (K/C) ratios mostly correspond to CaCO3 peaks, which suggests that the fine-grained particles in the Mendeleev Ridge are transported from the north coast Alaska and Canada where Mesozoic and Cenozoic strata are widely distributed. Thus, the Beaufort Gyre, the predominant surface current in the western Arctic Ocean, played an important role in the sediment delivery to the Mendeleev Ridge. It is worthy of note that the TOC and CaCO3 peaks are obviously distinct in the upper part of core MA01, whereas these peaks are reduced in the lower part of the core. More study on these contrasting features is in progress. References Adler, R.E., Polyak, L., Ortiz, J.D., Kaufman, D.S., Channell, J.E.T., Xuan, C., Grottoli, A.G., Sellén, E., and Crawford, K.A., 2009. Global and Planetary Change 68(1-2), 18-29. Polyak, L., Curry, W.B., Darby, D.A., Bischof, J., and Cronin, T.M., 2004. Palaeogeography, Palaeoclimatology, Palaeoecology 203, 73-93. Poore, R., Osterman, L., Curry, W., and Phillips, R., 1999. Geology 27, 759-762.

Park, Kwang-Kyu; Kim, Sunghan; Khim, Boo-Keun; Xiao, Wenshen; Wang, Rujian

2014-05-01

26

EDUCATION SYSTEM IN VEDIC PERIOD  

Directory of Open Access Journals (Sweden)

Full Text Available The basic aim of ancient education was instilling into the minds, of peoples aspirit of being pious and religious for glory of God and good of man. The pursuit ofknowledge was a pursuit of religious values. The student had to observe strictregulations. Instruction was important, but was even more significant than teaching wasdiscipline – discipline inculcated through strict obedience to laws and regulations ofstudent life, discipline that was rooted in morality and religion A student was required togive up lust, anger, greed, vanity, conceit and over joy. Education was free. It was freebecause no student was required to pay any fees. It was free also because no outsideagency could interfere in the matters of education. There was perfect autonomy. Noexternal authority no external beneficiary, no politics was permitted to enter the schoolor college system. A student had to pay nothing in return for education he received in aGurukul. The inculcation of civic virtues and social values was an equally importantobjective of education in India. The Brahmachari after his education in the Gurukulaswent back to the society to serve the rich and the poor, to relieve the diseased and thedistressed.

R.B.KOKATANUR

2013-05-01

27

Optimized Periodic Control of Chaotic Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this work, we demonstrate the open-loop control of chaotic systems by means of optimized periodic signals. The use of such signals enables us to reduce control power significantly in comparison to simple harmonic perturbations. It is found that the stabilized periodic dynamics can be changed by small, specific alterations of the control signal. Thus, low power switching between different periodic states can be achieved without feedback. The robustness of the proposed cont...

Mettin, Robert; Kurz, Thomas

1995-01-01

28

On the structure of the periodic system  

International Nuclear Information System (INIS)

A recently derived theorem on the level order for potential models is used to get information on the structure of the periodic system. The usual explanation for the level order is seen to be not precise enough. (Author)

1984-01-01

29

SQL Application for Periodic System of Elements  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents SQL power of periodic system using for didactic aim. The article is based on a PHP application developed to present a periodic system in a form, which can be used for answer at different questions, which can be asked related at the structure of elements. There are presented all queries that are needed to be use for classification of elements after different properties, the database, and user interface design.

Delia GLIGOR

2004-02-01

30

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

2011-07-01

31

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

32

Periodic thermodynamics of isolated quantum systems.  

Science.gov (United States)

The nature of the behavior of an isolated many-body quantum system periodically driven in time has been an open question since the beginning of quantum mechanics. After an initial transient period, such a system is known to synchronize with the driving; in contrast to the nondriven case, no fundamental principle has been proposed for constructing the resulting nonequilibrium state. Here, we analytically show that, for a class of integrable systems, the relevant ensemble is constructed by maximizing an appropriately defined entropy subject to constraints, which we explicitly identify. This result constitutes a generalization of the concepts of equilibrium statistical mechanics to a class of far-from-equilibrium systems, up to now mainly accessible using ad hoc methods. PMID:24785013

Lazarides, Achilleas; Das, Arnab; Moessner, Roderich

2014-04-18

33

Multichannel long period seismic data acquisition system  

International Nuclear Information System (INIS)

This paper discusses the specifications and performance of an eight channel long period seismic digital data acquisition system, which is developed and installed at Seismic Array Station, Gauribidanur, Karnataka State. The paper describes how these data in an unedited form are recorded on a single track of magnetic tape inter-mittantly, which has resulted in recording of 50 days data on a single tapespool. A time indexing technique which enables quick access to any desired portion of a recorded tape is also discussed. Typical examples of long period seismic event signals recorded by this system are also illustrated. Various advantages, the system provides over the analog multichannel instrumentation tape recording system, operating at Seismic Array Station for th e last two decades, are also discussed. (author). 7 figs

1990-01-01

34

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

2008-11-01

35

Periodic solutions for second order Hamiltonian systems  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper we present some recent multiplicity results for a class of second order Hamiltonian systems. Exploiting the variational structure of the problem, it will be shown how the existence of multiple, even infinitely many, periodic solutions can be assured.

Giuseppina D'Aguì

2011-06-01

36

Scaling Concepts in Periodically Modulated Noisy Systems  

CERN Document Server

We show that scaling arguments are very useful to analyze the dynamics of periodically modulated noisy systems. Information about the behavior of the relevant quantities, such as the signal-to-noise ratio, upon variations of the noise level, can be obtained by analyzing the symmetries and invariances of the system. In this way, it is possible to predict diverse physical manifestations of the cooperative behavior between noise and input signal, as for instance stochastic resonance, spatiotemporal stochastic resonance, and stochastic multiresonance.

Gómez-Vilar, J M

1997-01-01

37

The long period seismic system of Gauribidanur  

International Nuclear Information System (INIS)

This report describes the seismic long-period data acquisition system at Gauribidanur. The field electronics was designed to achieve a configuration of improved stability and dynamic range in the pass band of 0.025-0.1 hz. Some typical records obtained by the system are shown. Surface wave magnitudes estimated at the Gauribidanur Seismic Array are found to be in general agreement with those of international estimates. (author)

1981-01-01

38

Clustering of periodic orbits in chaotic systems  

Science.gov (United States)

In the framework of the semiclassical approach, the universal spectral correlations in Hamiltonian systems with classical chaotic dynamics can be attributed to the systematic correlations between the actions of periodic orbits which (up to the switch in the momentum direction) pass through approximately the same points of the phase space. By considering symbolic dynamics of the system one can introduce a natural ultrametric distance between periodic orbits and organize them into clusters of orbits approaching each other in the phase space. We study the distribution of cluster sizes for the baker's map in the asymptotic limit of long trajectories. This problem is equivalent to the one of counting degeneracies in the length spectrum of the de Bruijn graphs. Based on this fact, we derive the probability P_k that k randomly chosen periodic orbits belong to the same cluster. Furthermore, we find asymptotic behaviour of the largest cluster size |C_{\\max}| and derive the probability P(t) that a random periodic orbit belongs to a cluster smaller than t|C_{\\max}| , t ? [0, 1].

Gutkin, Boris; Osipov, Vladimir Al

2013-01-01

39

On periodic orbits in discrete-time cascade systems  

Directory of Open Access Journals (Sweden)

Full Text Available We present some results on existence, minimum period, number of periodic orbits, and stability of periodic orbits in discrete-time cascade systems. Some examples are presented to illustrate these results.

Xiao-Song Yang

2006-12-01

40

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

 
 
 
 
41

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

2007-08-01

42

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

1997-02-01

43

Periodicity  

Science.gov (United States)

In thinking about a title for this chapter, the word periodicity came to mind. I was sure this had some kind of pop culture reference. After discussing this with my wife, we figured I was thinking of synchronicity, which is a reference to music by the band, The Police. Looking the word Periodicity up on the internet, I found that I was, in fact, a science geek and had not made a hip reference. Periodicity refers mainly to the Periodic Table, which is a focus of this chapter. No music, just science.

Robertson, William C.

2007-01-01

44

Periodicals collection management using a decision support system  

Energy Technology Data Exchange (ETDEWEB)

Sandia National Laboratories is a multiprogram national laboratory established in 1949. The Library currently uses DOBIS for its automated system, including the Periodicals Control function for periodical check-in. DOBIS performs processing and control functions adequately, but could not meet our reporting needs. Therefore the Library`s Periodicals Decision Team decided that they needed another ``system`` for collection management. A Periodicals Decision Support System was created using information downloaded from DOBIS and uploaded into dBASE IV. The Periodical Decision Support System functions as an information-processing system that has aided us in making collection management decisions for periodicals. It certainly allows us to do interactive ad-hoc analysis; although there are no modeling tools currently incorporated in the system. We hope that these modeling tools will come later. We have been gathering information and developing needed reports to achieve this goal.

Compton, M.L.; Moser, E.C.

1993-12-31

45

Periodic orbits of nonscaling Hamiltonian systems from quantum mechanics  

International Nuclear Information System (INIS)

Quantal (E,?) plots are constructed from the eigenvalues of the quantum system. We demonstrate that these representations display the periodic orbits of the classical system, including bifurcations and the transition from stable to unstable

1995-03-01

46

Numerical Analysis on Periodic Response of Nonsmooth Dynamic Systems.  

Science.gov (United States)

The periodic response analysis of a nonlinear dynamic system, which is of great significant in engineering, is usually carried out by using numerical methods because of high dimension and complicated characters of the system. The current well-known numeri...

H. Hu

1993-01-01

47

Effective Hamiltonian approach to periodically perturbed quantum optical systems  

International Nuclear Information System (INIS)

We apply the method of Lie-type transformations to Floquet Hamiltonians for periodically perturbed quantum systems. Some typical examples of driven quantum systems are considered in the framework of this approach and corresponding effective time dependent Hamiltonians are found

2006-02-20

48

Periodic and Almost Periodic Solutions of the Volterra-Lotka System.  

Science.gov (United States)

In this paper is considered the Volterra-Lotka system of differential equations. This system models the interaction between n species in an (almost) periodic environment. Two cases are studied: one is a generalized form of the Volterra-Lotka competing spe...

X. Huang J. W. Reyn

1995-01-01

49

Stabilising periodic orbits in a chaotic system with hysteresis  

Energy Technology Data Exchange (ETDEWEB)

This paper considers the implementation of a control algorithm based on the theory of split-hyperbolicity. Control of chaotic systems generally uses assumptions regarding the hyperbolicity of the underlying dynamical system. However this cannot apply to systems with hysteresis. Through the application to a 'toy' model, control of a chaotic system with hysteresis is demonstrated, stabilising periodic orbits of various periods.

Namara, H Mc [Department of Applied Mathematics, University College Cork (Ireland)], E-mail: h.mcnamara@ucc.ie

2008-11-01

50

Global Entrainment of Transcriptional Systems to Periodic Inputs  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper addresses the problem of providing mathematical conditions that allow one to ensure that biological networks, such as transcriptional systems, can be globally entrained to external periodic inputs. Despite appearing obvious at first, this is by no means a generic property of nonlinear dynamical systems. Through the use of contraction theory, a powerful tool from dynamical systems theory, it is shown that certain systems driven by external periodic signals have the property that all...

Russo, Giovanni; Di Bernardo, Mario; Sontag, Eduardo D.

2010-01-01

51

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

52

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)

2006-09-18

53

Periodic orbits of Hamiltonian systems: Applications to perturbed Kepler problems  

International Nuclear Information System (INIS)

We provide for a class of Hamiltonian systems in the action–angle variables sufficient conditions for showing the existence of periodic orbits. We expand this result to the study of the existence of periodic orbits of perturbed spatial Keplerian Hamiltonians with axial symmetry. Finally, we apply these general results for finding periodic orbits of the Matese–Whitman Hamiltonian, of the spatial anisotropic Hamiltonian and of the spatial generalized van der Waals Hamiltonian

2013-12-01

54

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

55

Development of the safety management support system in shutdown period  

International Nuclear Information System (INIS)

In Japan, almost all configuration changes occur during plant shut down period. We have developed a system by which instantaneous risk during plant shutdown period is evaluated in a short time. The system is designed to allow plant personnel to easily calculate the plant risk in order to obtain and utilize risk information for safety management during shutdown period. To verify the system functions, verification tests were carried out using hypothetical refueling outage schedule in which plant configurations were changed much more frequently than in an actual refueling, outage. The system identified high-risk portion and its major contributor. Therefore we conclude that this system is useful and powerful tool for plant personnel in managing plant risk during plant shutdown period. (author)

2000-12-01

56

Periodicity of a class of nonlinear fuzzy systems with delays  

Energy Technology Data Exchange (ETDEWEB)

The well known Takagi-Sugeno (T-S) model gives an effective method to combine some simple local systems with their linguistic description to represent complex nonlinear dynamic systems. By using the T-S method, a class of local nonlinear systems having nice dynamic properties can be employed to represent some global complex nonlinear systems. This paper proposes to study the periodicity of a class of global nonlinear fuzzy systems with delays by using T-S method. Conditions for guaranteeing periodicity are derived. Examples are employed to illustrate the theory.

Yu Jiali [Computational Intelligence Laboratory, School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054 (China)], E-mail: yujiali@uestc.edu.cn; Yi Zhang [Computational Intelligence Laboratory, School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054 (China)], E-mail: zhangyi@uestc.edu.cn; Zhang Lei [Computational Intelligence Laboratory, School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054 (China)], E-mail: leilazhang@uestc.edu.cn

2009-05-15

57

Periodic Modulation Induced Increase of Reaction Rates in Autocatalytic Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. ...

Alarcon, T.; Perez-madrid, A.; Rubi, J. M.

1998-01-01

58

Time reversal in dynamically tuned zero-gap periodic systems.  

Science.gov (United States)

We show that short pulses propagating in zero-gap periodic systems can be reversed with 100% efficiency by using weak nonadiabatic tuning of the wave velocity at time scales that can be much slower than the period. Unlike previous schemes, we demonstrate reversal of broadband (few cycle) pulses with simple structures. Our scheme may thus open the way to time reversal in a variety of systems for which it was not accessible before. PMID:21668158

Sivan, Yonatan; Pendry, John B

2011-05-13

59

Periodic event-triggered control for nonlinear systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Resources limitations of embedded systems and networked control systems have motivated the development of novel controller implementation paradigms in order to reduce the potential conservatism of traditional clock-driven setups. In this context periodic event-triggered control has recently been proposed. Based on a periodically evaluated and state-dependent criterion, it is decided, at every sampling instant, whether the control input needs to be updated or not. In this paper we propose a me...

Postoyan, Romain; Anta, Adolfo; Heemels, W. P. M. H.; Tabuada, Paulo; Nesic, Dragan

2013-01-01

60

Periodic Solutions for a Discrete Mutual System with Delays  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, a discrete-time mutual system * is considered. By using coincidence degree and the related continuation the orem as well as prior estimates, easily sufficient conditions for the existence of positive periodic solutions are obtained,* if the following conditi * hold, then system has at least an w periodic solution. Our results are important complement to earlier results in the literature.(* Indicates a formula, please see the full text

CHEN Da-xue

2012-01-01

 
 
 
 
61

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

2008-07-01

62

Comparison of element compositions of Venus, Earth, Mars and chondrites in the light of D.I. Mendeleev's Periodic law  

International Nuclear Information System (INIS)

The part of free neutral atoms N0 of all elements being contained in protoplanet cloud is estimated with regard to their abundance and physicochemical properties. Linear dependence of ratio of volatile and nonvolatile elements in chondrites and in eruptive Earth rocks on N0 is obtained. Ratios of concentrations of element-analogs with different N0 in substances of Venus, Earth, Mars and chondrites are compared. Obtained data are an evidence that hypothetical process of magnetic separation in protoplanet cloud has been taken place

1999-01-01

63

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

1988-07-18

64

Phase control of resonant systems: Interference, chaos and high periodicity  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Much progress has been made in understanding the effect of periodic forcing on epidemiological and ecological systems when that forcing acts on just one part of the system. Much less is known about situations in which several parts of the system are affected. In this case the interaction between the impacts of the different forcing components can lead to reinforcement of system responses or to their interference. This interference phenomenon is significant if some forcing ...

2011-01-01

65

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 predictions

Maganza, Christian; Causse?, Rene?; Laloe?, Franck

1986-01-01

66

Localization of periodic orbits of polynomial systems by ellipsoidal estimates  

International Nuclear Information System (INIS)

In this paper we study the localization problem of periodic orbits of multidimensional continuous-time systems in the global setting. Our results are based on the solution of the conditional extremum problem and using sign-definite quadratic and quartic forms. As examples, the Rikitake system and the Lamb's equations for a three-mode operating cavity in a laser are considered

2005-02-01

67

Convergence Time towards Periodic Orbits in Discrete Dynamical Systems  

Science.gov (United States)

We investigate the convergence towards periodic orbits in discrete dynamical systems. We examine the probability that a randomly chosen point converges to a particular neighborhood of a periodic orbit in a fixed number of iterations, and we use linearized equations to examine the evolution near that neighborhood. The underlying idea is that points of stable periodic orbit are associated with intervals. We state and prove a theorem that details what regions of phase space are mapped into these intervals (once they are known) and how many iterations are required to get there. We also construct algorithms that allow our theoretical results to be implemented successfully in practice.

San Martin, Jesus; Porter, Mason A.

2014-01-01

68

Dynamical localization for two-level systems periodically driven  

Energy Technology Data Exchange (ETDEWEB)

Here, we consider a two-level system driven by an external periodic field. We show that the coherent destruction of tunnelling, as proved by Grossmann and co-workers (1991 Phys. Rev. Lett. 67 516; 1992 Europhys. Lett. 18 571) in the case of a monochromatic field, also appears for any periodic driving field given by an even regular function with zero mean value and satisfying a technical condition on the zeros of this function. (letter to the editor)

Lodi, Daniele; Maioli, Marco; Sacchetti, Andrea [Department of Mathematics, University of Modena and Reggio Emilia, Via Campi 213/B, 41100, Modena (Italy)

2005-01-14

69

Direct energy recovery system using periodic focusing without grids  

International Nuclear Information System (INIS)

Results from a computational study of the efficiency of a direct energy recovery system are presented. This system is similar to R.F. Post's original (gridless) periodic-focus system. However, the computer code used here allows more flexibility than that used by Post. His code requires analytic expressions for the potentials; this code requires only the values of potential on the boundaries. Consequently, the code can be applied to systems where analytic expressions have not been written for the potential. The incident beam used in this study had an average thickness of 0.42 m (as might be expected in an ideal reactor situation) and a maximum divergence angle of +-3.30. Each of the systems tested, when operating at optimum efficiency, recovered 80 percent of the energy, as compared to 91 percent for Post's gridded periodic system

1973-01-01

70

Distribution of periodic orbits in 2-D Hamiltonian systems  

Science.gov (United States)

We study the disribution of stable and unstable periodic orbits on a Poincare surface of section of a 2-D Hamiltonian system with the hamiltonian H = frac {1}{2}(Ax2+By2)+ frac {1}{2}(dot{x}2+dot{y}2) - epsilon xy2 as the pertubation increases. We find that the density of periodic orbits is larger in regions where the average stability is larger. This is explained by an ergodic argument. We distinguish beetween two kinds of periodic orbits. The regular ones which form lines according to Farey tree rules and the irregular ones which are very close to the asymptotic curves of the unstable periodic orbits. We show that inside the lobes of the homoclinic tangle only irregular periodic orbits appear and some of them are stable.We conjecture that the opposite is also true ie all irregular orbits are inside lobes. We also find that the homoclinic tangle has gaps caused by regular stable periodic orbits which have been trapped inside it. Similar results are found for the distribution of periodic orbits for the Hamiltonian system H = frac{1}{2}(dot{x}^2 + dot{y}^2 + x^2 + y^2) + y^4 + x^2y^2~~~~~~~~~. In this case the central periodic orbit of of period 1 it is unstable for small energies and has infinite transitions from stability to instability and vice versa as the energy increases.This behaviour is explained by solving the variational equations ,which reduce to a Mathiew equation.

Grousouzakou, E.; Contopoulos, G.; Polymilis, C.

71

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

72

Real numbers having ultimately periodic representations in abstract numeration systems  

CERN Document Server

Using a genealogically ordered infinite regular language, we know how to represent an interval of R. Numbers having an ultimately periodic representation play a special role in classical numeration systems. The aim of this paper is to characterize the numbers having an ultimately periodic representation in generalized systems built on a regular language. The syntactical properties of these words are also investigated. Finally, we show the equivalence of the classical "theta"-expansions with our generalized representations in some special case related to a Pisot number "theta".

Lecomte, P

2002-01-01

73

Global entrainment of transcriptional systems to periodic inputs.  

Science.gov (United States)

This paper addresses the problem of providing mathematical conditions that allow one to ensure that biological networks, such as transcriptional systems, can be globally entrained to external periodic inputs. Despite appearing obvious at first, this is by no means a generic property of nonlinear dynamical systems. Through the use of contraction theory, a powerful tool from dynamical systems theory, it is shown that certain systems driven by external periodic signals have the property that all their solutions converge to a fixed limit cycle. General results are proved, and the properties are verified in the specific cases of models of transcriptional systems as well as constructs of interest in synthetic biology. A self-contained exposition of all needed results is given in the paper. PMID:20418962

Russo, Giovanni; di Bernardo, Mario; Sontag, Eduardo D

2010-04-01

74

Periodic orbits near heteroclinic cycles in a cyclic replicator system.  

Science.gov (United States)

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. PMID:21656008

Wang, Yuanshi; Wu, Hong; Ruan, Shigui

2012-04-01

75

Positive periodic solutions of periodic neutral Lotka-Volterra system with distributed delays  

Energy Technology Data Exchange (ETDEWEB)

By using a fixed point theorem of strict-set-contraction, some criteria are established for the existence of positive periodic solutions of the following periodic neutral Lotka-Volterra system with distributed delays (dx{sub i}(t))/(dt) =x{sub i}(t)[a{sub i}(t)-{sigma}{sub j=1}{sup n}b{sub ij}(t){integral}{sub -T{sub ij}}{sup 0}K{sub ij}({theta})x{sub j}( t+{theta})d{theta}-{sigma}{sub j=1}{sup n}c{sub ij}(t){integral}{sub -T{sub ij}}{sup 0}K{sub ij}({theta}) x{sub j}{sup '}(t+{theta})d{theta}],i=1,2,...,n, where a{sub i},b{sub ij},c{sub ij} element of C(R,R{sup +}) (i, j = 1, 2, ..., n) are {omega}-periodic functions, T{sub ij},T{sub ij} element of (0,{infinity}) (i, j = 1, 2, ..., n) and K{sub ij},K{sub ij} element of (R,R{sup +}) satisfying {integral}{sub -T{sub ij}}{sup 0}K{sub ij}({theta})d{theta}=1,{integral}{sub -T{sub ij}}{sup 0}K{sub ij}({theta})d{theta}=1, i, j = 1, 2, ..., n.

Li Yongkun [Department of Mathematics, Yunnan University Kunming, Yunnan 650091 (China)], E-mail: yklie@ynu.edu.cn

2008-07-15

76

Many-body energy localization transition in periodically driven systems  

International Nuclear Information System (INIS)

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. -- Highlights: •A dynamical localization transition in periodically driven ergodic systems is found. •This phenomenon is reminiscent of many-body localization in energy space. •Our results are valid for classical and quantum systems in the thermodynamic limit. •At critical frequency, the short time expansion for the evolution operator breaks down. •The transition is associated to a divergent time scale

2013-06-01

77

Population Growth and Periodic Instability of the International System  

CERN Multimedia

From the perspective developed in this paper, it can be argued that exponential population growth resulted in the exponential decrease of the life-span of consecutive stable periods during the life-span of the European international system (1480-1945). However, it becomes evident as well that population growth as such is not a sufficient condition to generate a punctuated equilibrium dynamic in the war dynamics of the international system: other conditions and factors - and their interplay - contribute to this typical dynamic as well. From 1945 until the collapse of the Soviet Union (1991), the conditions of international system differed fundamentally from the conditions of the European international system during the period 1480-1945. It can be argued, that sooner or later a punctuated equilibrium war dynamic will resume.

Piepers, I

2006-01-01

78

Entropy production of diffusion in spatially periodic deterministic systems  

CERN Document Server

This paper presents an {\\it ab initio} derivation of the expression given by irreversible thermodynamics for the rate of entropy production for different classes of diffusive processes. The first class are Lorentz gases, where non-interacting particles move on a spatially periodic lattice, and collide elastically with fixed scatterers. The second class are periodic systems where $N$ particles interact with each other, and one of them is a tracer particle which diffuses among the cells of the lattice. We assume that, in either case, the dynamics of the system is deterministic and hyperbolic, with positive Lyapunov exponents. This work extends methods originally developed for a chaotic two-dimensional model of diffusion, the multi-baker map, to higher dimensional, continuous time dynamical systems appropriate for systems with one or more moving particles. Here we express the rate of entropy production in terms of hydrodynamic measures that are determined by the fractal properties of microscopic hydrodynamic mod...

Dorfman, J R; Gilbert, T

2002-01-01

79

Existence and continuation of periodic solutions of Newtonian systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.; Ratajczak, A.; Rybicki, S.

2006-01-01

80

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

 
 
 
 
81

Semiclassical quantization of KAM resonances in time-periodic systems  

Energy Technology Data Exchange (ETDEWEB)

A semiclassical theory for the quasi-energy spectrum of time-periodic systems with accidental classical resonances is presented. The primitive EBK quantum conditions for integrable systems are extended to multiply periodic flux tubes occurring in resonant systems. Replacing classical actions by appropriate differential operators in a classical resonance Hamiltonian yields a uniform quantization of states related to a classical resonance region. The derivation being general for time-periodic systems unfolds the organization of the quasi-energy spectrum, reducing it to the spectrum of a single time-independent Hamiltonian of one degree of freedom with additional rational shifts of h(cross) {omega}. In a first-order approximation the resonance Hamiltonian is reduced to a pendulum leading to a differential equation of the Mathieu type for the quasi-energies. It is rigorously shown how parameters of the differential equation can be drawn from classical dynamics, using the data of the 'essential' orbits in the resonance zone, i.e. stability coefficients and actions of hyperbolic and elliptic orbits as well as actions of homoclinic orbits. The quasi-energy spectrum of a forced quartic oscillator is studied numerically and evaluated. Semiclassical quasi-energies related to a resonance of period three are computed and compared with exact quantum mechanical eigenvalues. (author)

Mirbach, B.; Korsch, H.J. [Fachbereich Phys., Kaiserslautern Univ. (Germany)

1994-10-07

82

Semiclassical quantization of KAM resonances in time-periodic systems  

International Nuclear Information System (INIS)

A semiclassical theory for the quasi-energy spectrum of time-periodic systems with accidental classical resonances is presented. The primitive EBK quantum conditions for integrable systems are extended to multiply periodic flux tubes occurring in resonant systems. Replacing classical actions by appropriate differential operators in a classical resonance Hamiltonian yields a uniform quantization of states related to a classical resonance region. The derivation being general for time-periodic systems unfolds the organization of the quasi-energy spectrum, reducing it to the spectrum of a single time-independent Hamiltonian of one degree of freedom with additional rational shifts of h(cross) ?. In a first-order approximation the resonance Hamiltonian is reduced to a pendulum leading to a differential equation of the Mathieu type for the quasi-energies. It is rigorously shown how parameters of the differential equation can be drawn from classical dynamics, using the data of the 'essential' orbits in the resonance zone, i.e. stability coefficients and actions of hyperbolic and elliptic orbits as well as actions of homoclinic orbits. The quasi-energy spectrum of a forced quartic oscillator is studied numerically and evaluated. Semiclassical quasi-energies related to a resonance of period three are computed and compared with exact quantum mechanical eigenvalues. (author)

1994-10-07

83

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

1995-06-01

84

Existence of periodic solutions for nonlinear Lienard systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

85

Transport of quantum states of periodically driven systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We discuss the transport of quantum states on quasi-energy surfaces of periodically driven systems and establish their non-trivial structure. The latter is shown to be caused by diabatic transitions at lines of narrow avoided crossings. Some experimental consequences pertaining to adiabatic transport and Landau-Zener transitions among Floquet states are briefly sketched.

1990-01-01

86

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 respe...

Zhao, Guangyu; Ruan, Shigui

2011-01-01

87

On the busy period of discretization queuing system  

International Nuclear Information System (INIS)

By the method of recurrent events the reproducing function, the mean value, and the distribution of the number of customers, served during the busy period of a queueing system GI/GI/GI/infinity with a discretized input and infiiely many servers are investigated. In the case of the simplest flow and the discrete service time, the Laplace transforms and the mean values of the busy period and their cycle are determined. As a particular result the mean value and the Laplace transform of the discretized streamer blob length are obtained

1982-01-01

88

M|G|? queue system transient behaviour and busy period  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper main subject is the M|G|? queue system transient probabilities study as time functions. We achieve it completely when the time origin is an unoccupied system instant. But we do not get such a goal when the time origin is a busy period beginning instant. We shall see that, in this last situation, the service time length distribution hazard rate function plays a very important role. And so the results got may be useful in the survival analysis field. As the M G queue system can...

2003-01-01

89

Binary systems: implications for outflows & periodicities relevant to masers  

CERN Document Server

Bipolar molecular outflows have been observed and studied extensively in the past, but some recent observations of periodic variations in maser intensity pose new challenges. Even quasi-periodic maser flares have been observed and reported in the literature. Motivated by these data, we have tried to study situations in binary systems with specific attention to the two observed features, i.e., the bipolar flows and the variabilities in the maser intensity. We have studied the evolution of spherically symmetric wind from one of the bodies in the binary system, in the plane of the binary. Our approach includes the analytical study of rotating flows with numerical computation of streamlines of fluid particles using PLUTO code. We present the results of our findings assuming simple configurations, and discuss the implications.

Singh, Nishant K

2012-01-01

90

Periodic orbits of hybrid systems and parameter estimation via AD  

International Nuclear Information System (INIS)

Rhythmic, periodic processes are ubiquitous in biological systems; for example, the heart beat, walking, circadian rhythms and the menstrual cycle. Modeling these processes with high fidelity as periodic orbits of dynamical systems is challenging because: (1) (most) nonlinear differential equations can only be solved numerically; (2) accurate computation requires solving boundary value problems; (3) many problems and solutions are only piecewise smooth; (4) many problems require solving differential-algebraic equations; (5) sensitivity information for parameter dependence of solutions requires solving variational equations; and (6) truncation errors in numerical integration degrade performance of optimization methods for parameter estimation. In addition, mathematical models of biological processes frequently contain many poorly-known parameters, and the problems associated with this impedes the construction of detailed, high-fidelity models. Modelers are often faced with the difficult problem of using simulations of a nonlinear model, with complex dynamics and many parameters, to match experimental data. Improved computational tools for exploring parameter space and fitting models to data are clearly needed. This paper describes techniques for computing periodic orbits in systems of hybrid differential-algebraic equations and parameter estimation methods for fitting these orbits to data. These techniques make extensive use of automatic differentiation to accurately and efficiently evaluate derivatives for time integration, parameter sensitivities, root finding and optimization. The boundary value problem representing a periodic orbit in a hybrid system of differential algebraic equations is discretized via multiple-shooting using a high-degree Taylor series integration method (GM00, Phi03). Numerical solutions to the shooting equations are then estimated by a Newton process yielding an approximate periodic orbit. A metric is defined for computing the distance between two given periodic orbits which is then minimized using a trust-region minimization algorithm (DS83) to find optimal fits of the model to a reference orbit (Cas04). There are two different yet related goals that motivate the algorithmic choices listed above. The first is to provide a simple yet powerful framework for studying periodic motions in mechanical systems. Formulating mechanically correct equations of motion for systems of interconnected rigid bodies, while straightforward, is a time-consuming error prone process. Much of this difficulty stems from computing the acceleration of each rigid body in an inertial reference frame. The acceleration is computed most easily in a redundant set of coordinates giving the spatial positions of each body: since the acceleration is just the second derivative of these positions. Rather than providing explicit formulas for these derivatives, automatic differentiation can be employed to compute these quantities efficiently during the course of a simulation. The feasibility of these ideas was investigated by applying these techniques to the problem of locating stable walking motions for a disc-foot passive walking machine (CGMR01, Gar99, McG91). The second goal for this work was to investigate the application of smooth optimization methods to periodic orbit parameter estimation problems in neural oscillations. Others (BB93, FUS93, VB99) have favored non-continuous optimization methods such as genetic algorithms, stochastic search methods, simulated annealing and brute-force random searches because of their perceived suitability to the landscape of typical objective functions in parameter space, particularly for multi-compartmental neural models. Here we argue that a carefully formulated optimization problem is amenable to Newton-like methods and has a sufficiently smooth landscape in parameter space that these methods can be an efficient and effective alternative. The plan of this paper is as follows. In Section 1 we provide a definition of hybrid systems that is the basis for modeling systems with discontinuities or

2004-07-19

91

Periodic orbits of hybrid systems and parameter estimation via AD.  

Energy Technology Data Exchange (ETDEWEB)

Rhythmic, periodic processes are ubiquitous in biological systems; for example, the heart beat, walking, circadian rhythms and the menstrual cycle. Modeling these processes with high fidelity as periodic orbits of dynamical systems is challenging because: (1) (most) nonlinear differential equations can only be solved numerically; (2) accurate computation requires solving boundary value problems; (3) many problems and solutions are only piecewise smooth; (4) many problems require solving differential-algebraic equations; (5) sensitivity information for parameter dependence of solutions requires solving variational equations; and (6) truncation errors in numerical integration degrade performance of optimization methods for parameter estimation. In addition, mathematical models of biological processes frequently contain many poorly-known parameters, and the problems associated with this impedes the construction of detailed, high-fidelity models. Modelers are often faced with the difficult problem of using simulations of a nonlinear model, with complex dynamics and many parameters, to match experimental data. Improved computational tools for exploring parameter space and fitting models to data are clearly needed. This paper describes techniques for computing periodic orbits in systems of hybrid differential-algebraic equations and parameter estimation methods for fitting these orbits to data. These techniques make extensive use of automatic differentiation to accurately and efficiently evaluate derivatives for time integration, parameter sensitivities, root finding and optimization. The boundary value problem representing a periodic orbit in a hybrid system of differential algebraic equations is discretized via multiple-shooting using a high-degree Taylor series integration method [GM00, Phi03]. Numerical solutions to the shooting equations are then estimated by a Newton process yielding an approximate periodic orbit. A metric is defined for computing the distance between two given periodic orbits which is then minimized using a trust-region minimization algorithm [DS83] to find optimal fits of the model to a reference orbit [Cas04]. There are two different yet related goals that motivate the algorithmic choices listed above. The first is to provide a simple yet powerful framework for studying periodic motions in mechanical systems. Formulating mechanically correct equations of motion for systems of interconnected rigid bodies, while straightforward, is a time-consuming error prone process. Much of this difficulty stems from computing the acceleration of each rigid body in an inertial reference frame. The acceleration is computed most easily in a redundant set of coordinates giving the spatial positions of each body: since the acceleration is just the second derivative of these positions. Rather than providing explicit formulas for these derivatives, automatic differentiation can be employed to compute these quantities efficiently during the course of a simulation. The feasibility of these ideas was investigated by applying these techniques to the problem of locating stable walking motions for a disc-foot passive walking machine [CGMR01, Gar99, McG91]. The second goal for this work was to investigate the application of smooth optimization methods to periodic orbit parameter estimation problems in neural oscillations. Others [BB93, FUS93, VB99] have favored non-continuous optimization methods such as genetic algorithms, stochastic search methods, simulated annealing and brute-force random searches because of their perceived suitability to the landscape of typical objective functions in parameter space, particularly for multi-compartmental neural models. Here we argue that a carefully formulated optimization problem is amenable to Newton-like methods and has a sufficiently smooth landscape in parameter space that these methods can be an efficient and effective alternative. The plan of this paper is as follows. In Section 1 we provide a definition of hybrid systems that is the basis for modeling systems with discontinuities or

Guckenheimer, John. (Cornell University); Phipps, Eric Todd; Casey, Richard (INRIA Sophia-Antipolis)

2004-07-01

92

Disordered periodic systems at the upper critical dimension  

CERN Multimedia

The effects of weak point-like disorder on periodic systems at their upper critical dimension D_c for disorder are studied. The systems studied range from simple elastic systems with D_c=4 to systems with long range interactions with D_c=2 and systems with D_c=3 such as the vortex lattice with dispersive elastic constants. These problems are studied using the Gaussian Variational method and the Functional Renormalisation Group. In all the cases studied we find a typical ultra-slow loglog(x) growth of the asymptotic displacement correlation function, resulting in nearly perfect translational order. Consequences for the Bragg glass phase of vortex lattices are discussed.

Chitra, R; Le Doussal, P

1998-01-01

93

Periodic solutions of second order Hamiltonian systems bifurcating from infinity  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 cann...

Fura, J.; Rybicki, S.

2006-01-01

94

A Bode sensitivity integral for linear time-periodic systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

For linear time-invariant systems Bode's sensitivity integral is a well-known formula that quantifies some of thelimitations in feedback control. In this paper we show that a very similar formula holds for linear time-periodicsystems. We use the infinite-dimensional frequency-response operator called the harmonic transfer function to prove the result. It is shown that the harmonic transfer function isan analytic operator and a trace class operator under the assumption that the periodic sy...

Sandberg, Henrik; Bernhardsson, Bo

2004-01-01

95

Periodic orbits for an infinite family of classical superintegrable systems  

CERN Multimedia

We show that all bounded trajectories in the two dimensional classical system with the potential $V(r,\\phi)=\\omega^2 r^2+ \\frac{\\al k^2}{r^2 \\cos^2 {k \\phi}}+ \\frac{\\beta k^2}{r^2 \\sin^2 {k \\phi}}$ are closed for all integer and rational values of $k$. The period is $T=\\frac{\\pi}{2\\omega}$ and does not depend on $k$. This agrees with our earlier conjecture suggesting that the quantum version of this system is superintegrable.

Tremblay, Frédérick; Winternitz, Pavel

2009-01-01

96

Rigorous KAM results around arbitrary periodic orbits for Hamiltonian Systems  

CERN Document Server

We set up a methodology for computer assisted proofs of the existence and the KAM stability of an arbitrary periodic orbit for Hamiltonian systems. We give two examples of application for systems with 2 and 3 degrees of freedom. The first example verifies the existence of tiny elliptic islands inside large chaotic domains for a quartic potential. In the 3-body problem we prove the KAM stability of the well-known figure eight orbit and two selected orbits of the so called family of rotating Eights. Some additional theoretical and numerical information is also given for the dynamics of both examples.

Kapela, Tomasz

2011-01-01

97

A Bode Sensitivity Integral for Linear Time-Periodic Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Bode's sensitivity integral is a well-known formula that quantifies some of the limitations in feedback control for linear time-invariant systems. In this note, we show that there is a similar formula for linear time-periodic systems. The harmonic transfer function is used to prove the result. We use the notion of roll-off 2, which means that the first time-varying Markov parameter is equal to zero. It then follows that the harmonic transfer function is an analytic operator and a trace cl...

Sandberg, Henrik; Bernhardsson, Bo

2005-01-01

98

Constraint Based Computation of Periodic Orbits of Chaotic Dynamical Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The chaos theory emerged at the end of the 19th century, and it has given birth to a deep mathematical theory in the 20th century, with a strong practical impact (e.g., weather forecast, turbulence analysis). Periodic orbits play a key role in understanding chaotic systems. Their rigorous computation provides some insights on the chaotic behavior of the system and it enables computer assisted proofs of chaos related properties (e.g., topological entropy). In this paper, we show that the (nume...

Goldsztejn, Alexandre; Granvilliers, Laurent; Jermann, Christophe

2013-01-01

99

Structural Responses of Infinite Periodic Systems to Electrostatic Fields  

Science.gov (United States)

A method for determining electronic and structural responses of infinite, periodic systems to electromagnetic fields, based on the vector potential approach (VPA), is reviewed. We focus particularly on the structural responses of quasi-one-dimensional systems to static fields. Analytical expressions for the Hartree-Fock forces are given. It is shown that the responses depend upon a term involving an unknown integer, which is related to the phase factors for the crystal orbitals. Using a model Hamiltonian the importance of this term is explicitly demonstrated for the piezoelectric effect. A simple practical procedure suffices for obtaining the value of the unknown integer.

Springborg, Michael; Kirtman, Bernard; Tevekeliyska, Violina

2009-08-01

100

Kinetic energy density functionals for non-periodic systems  

CERN Multimedia

Kinetic energy functionals of the electronic density are used to model large systems in the context of density functional theory, without the need to obtain electronic wavefunctions. We discuss the problems associated with the application of widely used kinetic energy functionals to non-periodic systems. We develop a method that circumvents this difficulty and allows the kinetic energy to be evaluated entirely in real space. We demonstrate that the method is efficient [O(N)] and accurate by comparing the results of our real-space formulation to calculations performed in reciprocal space, and to calculations using traditional approaches based on electronic states.

Choly, N; Choly, Nicholas; Kaxiras, Efthimios

2001-01-01

 
 
 
 
101

On resumming periodic orbits in the spectra of integrable systems  

CERN Document Server

Spectral determinants have proven to be valuable tools for resumming the periodic orbits in the Gutzwiller trace formula of chaotic systems. We investigate these tools in the context of integrable systems to which these techniques have not been previously applied. Our specific model is a stroboscopic map of an integrable Hamiltonian system with quadratic action dependence, for which each stage of the semiclassical approximation can be controlled. It is found that large errors occur in the semiclassical traces due to edge corrections which may be neglected if the eigenvalues are obtained by Fourier transformation over the long time dynamics. However, these errors cause serious harm to the spectral approximations of an integrable system obtained via the spectral determinants. The symmetry property of the spectral determinant does not generally alleviate the error, since it sometimes sheds a pair of eigenvalues from the unit circle. By taking into account the leading order asymptotics of the edge corrections, th...

D'Almeida, A M O; Tomsovic, S; Almeida, Alfredo M. Ozorio de; Lewenkopf, Caio H.; Tomsovic, Steven

2002-01-01

102

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

103

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

104

Rotational mixing in massive binaries: detached short-period systems  

CERN Multimedia

Models of rotating single stars can successfully account for a wide variety of observed stellar phenomena, such as the surface enhancements of N and He. However, recent observations have questioned the idea that rotational mixing is the main process responsible for the surface enhancements, emphasizing the need for a strong and conclusive test. We investigate the consequences of rotational mixing for massive main-sequence stars in short-period binaries. In these systems the tides spin up the stars to rapid rotation. We use a state-of-the-art stellar evolution code including the effect of rotational mixing, tides, and magnetic fields. We discuss the surface abundances expected in massive close binaries (M1~20 solar masses) and we propose using such systems to test the concept of rotational mixing. As these short-period binaries often show eclipses, their parameters can be determined with high accuracy, allowing for a direct comparison with binary evolution models. In more massive close systems (M1~50 solar mas...

de Mink, S E; Langer, N; Pols, O R; Brott, I; Yoon, S -Ch

2009-01-01

105

Grid-free density functional calculations on periodic systems.  

Science.gov (United States)

Density fitting scheme is applied to the exchange part of the Kohn-Sham potential matrix in a grid-free local density approximation for infinite systems with translational periodicity. It is shown that within this approach the computational demands for the exchange part scale in the same way as for the Coulomb part. The efficiency of the scheme is demonstrated on a model infinite polymer chain. For simplicity, the implementation with Dirac-Slater Xalpha exchange functional is presented only. Several choices of auxiliary basis set expansion coefficients were tested with both Coulomb and overlap metric. Their effectiveness is discussed also in terms of robustness and norm preservation. PMID:17887829

Varga, Stefan

2007-09-21

106

Large gaps in point-coupled periodic systems of manifolds  

International Nuclear Information System (INIS)

We study a free quantum motion on periodically structured manifolds composed of elementary two-dimensional 'cells' connected either by linear segments or through points where the two cells touch. The general theory is illustrated with numerous examples in which the elementary components are spherical surfaces arranged into chains in a straight or zigzag way, or two-dimensional square lattice 'carpets'. We show that the spectra of such systems have an infinite number of gaps and that the latter dominate the spectrum at high energies

2003-05-02

107

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

108

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/.

Huttunen Heikki

2005-05-01

109

Singular Continuous Floquet Operator for Periodic Quantum Systems  

CERN Multimedia

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

110

Periodic motions and bifurcations of a vibro-impact system  

International Nuclear Information System (INIS)

Based on the analysis of a two-degree-of-freedom plastic impact oscillator, we introduce a three-dimensional map with dynamical variables defined at the impact instants. The non-linear dynamics of the vibro-impact system is analyzed by using the Poincare map, in which piecewise property and singularity are found to exist. The piecewise property is caused by the transitions of free flight and sticking motions of two masses immediately after the impact, and the singularity of map is generated via the grazing contact of two masses and corresponding instability of periodic motions. These properties of the map have been shown to exhibit particular types of sliding and grazing bifurcations of periodic-impact motions under parameter variation. Simulations of the free flight and sticking solutions are carried out, and regions of existence and stability of different impact motions are therefore presented in (?, ?) plane of dimensionless clearance ? and frequency ?. The influence of non-standard bifurcations on dynamics of the vibro-impact system is elucidated accordingly

2008-06-01

111

The Shortest Period Detached Binary White Dwarf System  

CERN Document Server

We identify SDSS J010657.39-100003.3 (hereafter J0106-1000) as the shortest period detached binary white dwarf (WD) system currently known. We targeted J0106-1000 as part of our radial velocity program to search for companions around known extremely low-mass (ELM, ~ 0.2 Msol) WDs using the 6.5m MMT. We detect peak-to-peak radial velocity variations of 740 km/s with an orbital period of 39.1 min. The mass function and optical photometry rule out a main-sequence star companion. Follow-up high-speed photometric observations obtained at the McDonald 2.1m telescope reveal ellipsoidal variations from the distorted primary but no eclipses. This is the first example of a tidally distorted WD. Modeling the lightcurve, we constrain the inclination angle of the system to be 67 +- 13 deg. J0106-1000 contains a pair of WDs (0.17 Msol primary + 0.43 Msol invisible secondary) at a separation of 0.32 Rsol. The two WDs will merge in 37 Myr and most likely form a core He-burning single subdwarf star. J0106-1000 is the shortest...

Kilic, Mukremin; Kenyon, S J; Prieto, Carlos Allende; Andrews, J; Kleinman, S J; Winget, K I; Winget, D E; Hermes, J J

2011-01-01

112

Optimal stabilization of unstable periodic orbits embedded in chaotic systems  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish En este artículo se propone un enfoque basado en el flujo gradiente con el propósito de estabilizar órbitas periódicas inestables inmersas en sistemas caóticos. Tal enfoque considera al problema de estabilización como un problema de control óptimo, lo cual permite obtener una solución en línea al pr [...] oblema de interés, para lo cual se introduce el cálculo de las sensibilidades de los estados con respecto a la entrada de control. El controlador por retroalimentación resultante permite estabilizar órbitas periódicas inestables inmersas en ambas clases de sistemas caoticos, con o sin número de Floquet impar. Además, el enfoque propuesto se extiende para identificar el periodo de la órbita periódica inestable a ser estabilizada, en el caso en que este sea desconocido. Se realizan experimentos de simulación del controlador propuesto, para estabilizar orbitas periódicas inestables de los sistemas de Rössler y de Lorenz. Abstract in english A gradient-flow-based approach is proposed in this paper for stabilizing unstable periodic orbits (UPO) embedded in chaotic systems. In order to obtain an on-line stabilizing solution, the stabilization problem is considered to be an optimal control problem, and system state sensitivities with respe [...] ct to the control input are introduced. The resulting feedback controller is able to stabilize UPO embedded in both kind of systems, with or without an odd Floquet number. Moreover, the proposed approach is easily extended to identifying the period of the UPO to be stabilized when it is unknown. Simulation experiments of the proposed controller are carried out on the Rössler and the Lorenz systems.

C.A., Cruz-Villar.

113

Quasi-periodic and non-periodic waves in the (2 + 1)-dimensional generalized Broer-Kaup system  

International Nuclear Information System (INIS)

For a higher-dimensional integrable nonlinear dynamical system, there are abundant coherent soliton excitations. With the aid of an improved projective Riccati equation approach, the paper obtains several types of exact solutions to the (2 + 1)-dimensional generalized Broer-Kaup system, including multiple soliton solutions, periodic soliton solutions and Weierstrass function solutions. From which, new quasi-periodic and non-periodic excitations for the system are studied by means of the Jacobi elliptic functions with the space-time-dependent modulus

2007-10-01

114

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

2005-10-27

115

Periodic inspection optimization model for a complex repairable system  

Energy Technology Data Exchange (ETDEWEB)

This paper proposes a model to find the optimal periodic inspection interval on a finite time horizon for a complex repairable system. In general, it may be assumed that components of the system are subject to soft or hard failures, with minimal repairs. Hard failures are either self-announcing or the system stops when they take place and they are fixed instantaneously. Soft failures are unrevealed and can be detected only at scheduled inspections but they do not stop the system from functioning. In this paper we consider a simple policy where soft failures are detected and fixed only at planned inspections, but not at moments of hard failures. One version of the model takes into account the elapsed times from soft failures to their detection. The other version of the model considers a threshold for the total number of soft failures. A combined model is also proposed to incorporate both threshold and elapsed times. A recursive procedure is developed to calculate probabilities of failures in every interval, and expected downtimes. Numerical examples of calculation of optimal inspection frequencies are given. The data used in the examples are adapted from a hospital's maintenance data for a general infusion pump.

Taghipour, Sharareh, E-mail: sharareh@mie.utoronto.c [Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ont., M5S 3G8 (Canada); Banjevic, Dragan; Jardine, Andrew K.S. [Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ont., M5S 3G8 (Canada)

2010-09-15

116

The Generalized Gronwall Inequality and Its Application to Periodic Solutions of Integrodifferential Impulsive Periodic System on Banach Space  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract This paper deals with a class of integrodifferential impulsive periodic systems on Banach space. Using impulsive periodic evolution operator given by us, the -periodic PC-mild solution is introduced and suitable Poincaré operator is constructed. Showing the compactness of Poincaré operator and using a new generalized Gronwall's inequality with impulse, mixed type integral operators and -norm given by us, we utilize Leray-Schauder fixed point theorem to prove the existence of -periodic PC-mild solutions. Our method is much different from methods of other papers. At last, an example is given for demonstration.

Wei W

2008-01-01

117

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

118

Extension of the Periodic System: Superheavy, Superneutronic, Superstrange, Antimatter Nuclei  

International Nuclear Information System (INIS)

The possibilities for the extension of the periodic system into the islands of superheavy (SH) elements, to and beyond the neutron drip line and to the sectors of strangeness and antimatter are discussed in the paper. The multi-nucleon transfer processes in low-energy damped collisions of heavy actinide nuclei may help us to fill the gap between the nuclei produced in the 'hot' fusion reactions and the continent of known nuclei. In these reactions we may also investigate the 'island of stability'. In many such collisions the lifetime of the composite giant system consisting of two touching nuclei turns out to be rather long (?10-20 s); sufficient for observing line structure in spontaneous positron emission from super-strong electric fields (vacuum decay), a fundamental QED process not observed yet experimentally. A tremendously rich scenario of new nuclear structure emerges with new magic numbers in the strangeness domain. Various production mechanisms are discussed for these objects and for antinuclei in high energy heavy-ion collisions.

2010-03-01

119

Extension of the Periodic System: Superheavy, Superneutronic, Superstrange, Antimatter Nuclei  

Science.gov (United States)

The possibilities for the extension of the periodic system into the islands of superheavy (SH) elements, to and beyond the neutron drip line and to the sectors of strangeness and antimatter are discussed in the paper. The multi-nucleon transfer processes in low-energy damped collisions of heavy actinide nuclei may help us to fill the gap between the nuclei produced in the “hot” fusion reactions and the continent of known nuclei. In these reactions we may also investigate the “island of stability”. In many such collisions the lifetime of the composite giant system consisting of two touching nuclei turns out to be rather long (?10-20 s); sufficient for observing line structure in spontaneous positron emission from super-strong electric fields (vacuum decay), a fundamental QED process not observed yet experimentally. A tremendously rich scenario of new nuclear structure emerges with new magic numbers in the strangeness domain. Various production mechanisms are discussed for these objects and for antinuclei in high energy heavy-ion collisions.

Greiner, Walter; Zagrebaev, Valery

2010-03-01

120

Controlling Chaotic Rossler System via Synchronization, Using Bifurcation Parameter to Choose Desirable Periodic Orbit  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, using synchronization approach, chaos control for Rössler system is investigated. Based on essential structure of synchronization approach and using bifurcation diagram, periodic Rössler systems or master systems for both period-one and period-two orbits are found. Nonlinear and linear feedback methods are used to synchronize chaotic slave system with periodic master systems. Stability conditions are discussed analytically and numerical simulation results are presented.

H. Fatehi Marj

2009-01-01

 
 
 
 
121

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

122

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.

2013-05-01

123

Quantum diffusion in semi-infinite periodic and quasiperiodic systems  

International Nuclear Information System (INIS)

This paper studies quantum diffusion in semi-infinite one-dimensional periodic lattice and quasiperiodic Fibonacci lattice. It finds that the quantum diffusion in the semi-infinite periodic lattice shows the same properties as that for the infinite periodic lattice. Different behaviour is found for the semi-infinite Fibonacci lattice. In this case, there are still C(t) ? t?? and d(t) ? t?. However, it finds that 0 < ? < 1 for smaller time, and ? = 0 for larger time due to the influence of surface localized states. Moreover, ? for the semi-infinite Fibonacci lattice is much smaller than that for the infinite Fibonacci lattice. Effects of disorder on the quantum diffusion are also discussed

2008-03-01

124

Periodic orbits and their bifurcations in a 3-D system  

Science.gov (United States)

We study some simple periodic orbits and their bifurcations in the Hamiltonian (H = 1/2 ((x dot)2 + (y dot)2 + (z dot)2 + Ax2 + By2 + Cz2) - epsilon xz2 - eta yz2. We give the forms of the orbits, the characteristics of the main families, and some existence diagrams and stability diagrams. The existence diagram of the family 1a contains regions that are stable (S), simply unstable (U), doubly unstable (DU) and complex unstable (Delta). In the regions S and U there are lines of equal rotation number m/n. Along these lines we have bifurcations of families of periodic orbits of multiplicity n. When these lines reach the boundary of the complex unstable region, they are tangent to it. Inside the region Delta there are lines m/n, along which the orbits 1a, described n-times, are doubly unstable; however, along these lines there are no bifurcations of n-ple periodic orbits. The families bifurcating from 1a exist only in certain regions of the parameter space (epsilon, eta). The limiting lines of these regions join at particular points representing collisions of bifurcations. These collisions of bifurcations produce a nonuniqueness of the various families of periodic orbits. The complicated structure of the various bifurcations can be understood by constructing appropriate stability diagrams.

Contopoulos, G.; Barbanis, B.

1994-07-01

125

Wannier Functions in a Simple Non-Periodic System.  

Science.gov (United States)

The paper defines and analyzes in detail the Wannier functions a(l) of a one-dimensional periodic lattice with a point defect. It is shown that these functions have exactly the same exponential localization as the Wannier functions of the perfect lattice ...

W. Kohn J. R. Onffroy

1973-01-01

126

Analytical investigation of revival phenomena in periodically driven system  

CERN Document Server

We present theoretical study of revival phenomena for a wave packet initially well localized in a one-dimensional potential in the presence of an external periodic modulating field. The classical motion, revival, and super-revival time scale are derived exactly for wave packet excited in the one dimension box potential.

Shahzad, Muhammad A

2010-01-01

127

Signatures of resonant terrestrial planets in long-period systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The majority of extrasolar planets discovered to date have significantly eccentric orbits, some if not all of which may have been produced through planetary migration. During this process, any planets interior to such an orbit would therefore have been susceptible to resonance capture, and hence may exhibit measurable orbital period variations. Here we summarize the results of our investigation into the possibility of detecting low-mass planets which have been captured into ...

Kennedy, Gareth F.; Mardling, Rosemary A.

2009-01-01

128

Branching of periodic orbits in reversible hamiltonian systems  

CERN Document Server

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

129

On-Iine Management System for the Periodicals in JAERl  

Science.gov (United States)

The article describes the outlines of the on-line serials control system utilizing a mini-computer. The system is dealt with subscription, check-in, claiming, inquiry of serials information and binding of journals. In this system journal acquisition with serial arrival prediction in an on-line mode is carried on a priority principle to record the actual receipt of incoming issues.

Itabashi, Keizo; Mineo, Yukinobu

130

Maximal Regularity of the Time - Periodic Linearized Navier-Stokes System  

Science.gov (United States)

Time-periodic solutions to the linearized Navier-Stokes system in the n-dimensional whole-space are investigated. For time-periodic data in L q -spaces, maximal regularity and corresponding a priori estimates for the associated time-periodic solutions are established. More specifically, a Banach space of time-periodic vector fields is identified with the property that the linearized Navier-Stokes operator maps this space homeomorphically onto the L q -space of time-periodic data.

Kyed, Mads

2014-03-01

131

Feedback control in a general almost periodic discrete system of plankton allelopathy.  

Science.gov (United States)

We study the properties of almost periodic solutions for a general discrete system of plankton allelopathy with feedback controls and establish a theorem on the uniformly asymptotic stability of almost periodic solutions. PMID:24592189

Yin, Wenshuang

2014-01-01

132

Controlling chaos in a high dimensional system with periodic parametric perturbations.  

Science.gov (United States)

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 orb...

K. A. Mirus J. C. Sprott

1998-01-01

133

Forced periodic vibration of unsymmetric piecewise-linear systems  

Science.gov (United States)

The forced steady response of a single degree of freedom system involving a large nonlinearity, represented by unsymmetric piecewise-linear stiffness, is determined by a harmonic balance Newton-Raphson method with the application of the fast Fourier transformation (FFT) algorithm. All possible subharmonic, harmonic, and superharmonic responses are sought. The responses of two systems involving subharmonic and superharmonic dominant motions are calculated by the newly developed method and compared with previously published findings. The results obtained by using this method reveal the details of the response of the systems more efficiently than previous methods.

Choi, Y. S.; Noah, S. T.

1988-01-01

134

Periodic orbit quantization of chaotic systems with strong pruning  

CERN Multimedia

The three-disk system, which for many years has served as a paradigm for the usefulness of cycle expansion methods, represents an extremely hard problem to semiclassical quantization when the disks are moved closer and closer together, since (1) pruning of orbits sets in, rendering the symbolic code incomplete, and (2) the number of orbits necessary to obtain accurate semiclassical eigenvalues proliferates exponentially. In this note we show that an alternative method, viz. harmonic inversion, which does not rely on the existence of complete symbolic dynamics or other specific properties of systems, provides a key to solving the problem of semiclassical quantization of systems with strong pruning. For the closed three-disk system we demonstrate how harmonic inversion, augmented by a signal cross-correlation technique, allows one to semiclassically calculate the energies up to the 28th excited state with high accuracy.

Weibert, K; Wunner, G

2002-01-01

135

Linear Impulsive Periodic System with Time-Varying Generating Operators on Banach Space  

Directory of Open Access Journals (Sweden)

Full Text Available A class of the linear impulsive periodic system with time-varying generating operators on Banach space is considered. By constructing the impulsive evolution operator, the existence of T0-periodic PC-mild solution for homogeneous linear impulsive periodic system with time-varying generating operators is reduced to the existence of fixed point for a suitable operator. Further the alternative results on T0-periodic PC-mild solution for nonhomogeneous linear impulsive periodic system with time-varying generating operators are established and the relationship between the boundness of solution and the existence of T0-periodic PC-mild solution is shown. The impulsive periodic motion controllers that are robust to parameter drift are designed for a given periodic motion. An example given for demonstration.

JinRong Wang

2007-10-01

136

Linear Impulsive Periodic System with Time-Varying Generating Operators on Banach Space  

Directory of Open Access Journals (Sweden)

Full Text Available A class of the linear impulsive periodic system with time-varying generating operators on Banach space is considered. By constructing the impulsive evolution operator, the existence of -periodic -mild solution for homogeneous linear impulsive periodic system with time-varying generating operators is reduced to the existence of fixed point for a suitable operator. Further the alternative results on -periodic -mild solution for nonhomogeneous linear impulsive periodic system with time-varying generating operators are established and the relationship between the boundness of solution and the existence of -periodic -mild solution is shown. The impulsive periodic motion controllers that are robust to parameter drift are designed for a given periodic motion. An example given for demonstration.

Wei W

2007-01-01

137

Control of a unified chaotic system with delayed continuous periodic switch  

International Nuclear Information System (INIS)

A unified chaotic system with delayed continuous periodic switch is put forward based on the newly presented chaotic system with continuous periodic switch. This new system is more comprehensive and displays much richer dynamic behavior. The adaptive control and time-delay feedback control are concluded. In particular, we can find many unstable periodic orbits and stabilize them by the time-delay feedback technique. Theoretical analysis and numerical simulations show the effectiveness of these methods

2004-10-01

138

The European debate on rate systems in the interwar period  

Energy Technology Data Exchange (ETDEWEB)

This article describes a particular branch that evolved in the diffusion of electrical rate systems in twentieth-century Europe and the debate that ensued between the competitive, promotional and cost based approaches. Three major questions are addressed: What factors and historical circumstances favoured the emergence of more or less efficient pricing schemes? Why did some enterprises opt for promotional rates while others defended the cost based alternative? What is the historical origin of marginal cost pricing? It is shown how the volatility of the costs that characterize hydro-electric production made this particular technology very sensitive to a cost approach towards pricing and to a seasonal and time-of-day perspective on rate systems. (author)

Madureira, Nuno Luis [ISCTE cacifo 321B, Av Forcas Armadas, 1600 Lisboa (Portugal)

2010-08-15

139

Statistical properties of periodic orbits in 4-disk billiard system: pruning-proof property  

CERN Document Server

Periodic orbit theory for classical hyperbolic system is very significant matter of how we can interpret spectral statistics in terms of semiclassical theory. Although pruning is significant and generic property for almost all hyperbolic systems, pruning-proof property for the correlation among the periodic orbits which gains a resurgence of second term of the random matrix form factor remains open problem. In the light of the semiclassical form factor, our attention is paid to statistics for the pairs of periodic orbits. Also in the context of pruning, we investigated statistical properties of the ``actual'' periodic orbits in 4-disk billiard system. This analysis presents some universality for pair-orbits' statistics. That is, even if the pruning progress, there remains the periodic peak structure in the statistics for periodic orbit pairs. From such the property, we claim that if the periodic peak structure contributes to the correlation, namely the off-diagonal part of the semiclassical form factor, then ...

Asamizuya, T

2005-01-01

140

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 awa...

Larsen, Martin Birkelund; Blanke, Mogens

2009-01-01

 
 
 
 
141

Impulsive control, complete and lag synchronization of unified chaotic system with continuous periodic switch  

International Nuclear Information System (INIS)

The new unified chaotic system with continuous periodic switch between Lorenz and Chen systems is non-autonomous ones, which has many properties, such as symmetry and invariance, dissipative, tracking any target function etc. Control and synchronization of complete and lag for the system are discussed based on impulsive control theory in this paper. Some new general criteria for global asymptotical stability of continuous periodic switch system are established, and particularly some simple sufficient conditions are derived for stabilizing, complete and lag synchronizing chaotic system with continuous periodic switch. Theoretical analysis and numerical simulations are provided to show the effectiveness and feasibility of these methods

2005-11-01

142

Existence of periodic travelling waves in systems of nonlinear oscillators on 2Dlattice (in Ukrainian  

Directory of Open Access Journals (Sweden)

Full Text Available It is considered the system of differential equations that describes the dynamics of an infinite system of linearly coupled nonlinear oscillators on 2D-lattice. Results on existence of the periodic travelling waves are obtained.

S. M. Bak

2011-03-01

143

The cyclicity of period annulus of a quadratic reversible Lotka–Volterra system  

International Nuclear Information System (INIS)

We prove that by perturbing the periodic annulus of the quadratic polynomial reversible Lotka–Volterra differential system, inside the class of all quadratic polynomial differential systems we can obtain at most two limit cycles

2009-12-01

144

Quasilinearization for the periodic boundary value problem for systems of impulsive differential equations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The method of generalized quasilinearization for the system of nonlinear impulsive differential equations with periodic boundary conditions is studied. As a byproduct, the result for the system without impulses can be obtained, which is a new result as well.

2006-01-01

145

The virial theorem and exact properties of density functionals for periodic systems  

CERN Multimedia

In the framework of density functional theory, scaling and the virial theorem are essential tools for deriving exact properties of density functionals. Preexisting mathematical difficulties in deriving the virial theorem via scaling for periodic systems are resolved via a particular scaling technique. This methodology is employed to derive universal properties of the exchange-correlation energy functional for periodic systems.

Mirhosseini, H; Baldsiefen, T; Sanna, A; Proetto, C R; Gross, E K U

2014-01-01

146

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

147

Period-doubling bifurcations and routes to chaos of the vibratory systems contacting stops  

International Nuclear Information System (INIS)

A two-degree-of-freedom vibratory system contacting a single rigid stop is considered. The stop leads motions with repeat impacts, i.e., vibro-impacts. Such models play an important role in the studies of mechanical systems with amplitude constraining stops. Some non-typical routes to chaos, via period-doubling bifurcations of periodic motions with one impact, are studied. The period-doubling cascades of periodic orbits with one impact are usually discontinuous in the transition of periodic impact to chaos, in which there exist grazing bifurcation, torus bifurcation or Hopf bifurcation associated with multi-impact motions with higher period. A two-degree-of-freedom system having symmetrically placed rigid stops and subjected to periodic excitation is considered also. The system may exhibit more complicated dynamical behavior in the route to chaos via pitchfork bifurcation of period-one double-impact symmetrical motion. The routes to chaos, appearing in the vibro-impact systems, are qualitatively different form the typical period-doubling route to chaos in the usual consecutive maps

2004-03-22

148

Dynamics of a periodic Watt-type predator-prey system with impulsive effect  

International Nuclear Information System (INIS)

In this paper, an impulsive periodic predator-prey system with Watt-type functional response is investigated. By using the Floquet theory of linear periodic impulsive equation, the stability conditions for the prey-eradication positive periodic solution are given, and the boundedness of the system is proved. By the method of coincidence degree, the sufficient conditions for the existence of at least one strictly positive periodic solution are obtained. Furthermore, we give numerical analysis to confirm our theoretical results. It will be useful for ecosystem control.

2009-02-15

149

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

150

Periodic Solutions for Nonlinear Integro-Differential Systems with Piecewise Constant Argument  

Science.gov (United States)

We investigate the existence of the periodic solutions of a nonlinear integro-differential system with piecewise alternately advanced and retarded argument of generalized type, in short DEPCAG; that is, the argument is a general step function. We consider the critical case, when associated linear homogeneous system admits nontrivial periodic solutions. Criteria of existence of periodic solutions of such equations are obtained. In the process we use Green's function for periodic solutions and convert the given DEPCAG into an equivalent integral equation. Then we construct appropriate mappings and employ Krasnoselskii's fixed point theorem to show the existence of a periodic solution of this type of nonlinear differential equations. We also use the contraction mapping principle to show the existence of a unique periodic solution. Appropriate examples are given to show the feasibility of our results.

2014-01-01

151

Gradient Based Control and Synchronization of Lorenz System with Periodic Parametric Forcing  

Directory of Open Access Journals (Sweden)

Full Text Available Several important properties of chaos synchronization with gradientbased control of chaotic system with periodic parametric forcing remainstill unexplored. This paper investigates the behavior of the Lorenz systemto change from chaotic to periodic, parametric forcing also entrainsthe system output with the forcing frequency. Secondly synchronizationof two identically chaotic Lorenz systems are derived by linear feedbackcontrol and then discussed the gradient based control method for Lorenzsystem with periodic parametric forcing. Finally numerical simulationresults are presented to show the feasibility and effectiveness of the approach.

Mohammad Ali Khan

2012-08-01

152

Dynamic behaviors of the periodic Lotka-Volterra competing system with impulsive perturbations  

Energy Technology Data Exchange (ETDEWEB)

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.

Liu Bing [Department of Mathematics, Anshan Normal University, Anshan 114005, Liaoning (China) and Department of Mathematics, Xinjiang University, Urumqi 830046, Xinjiang (China)]. E-mail: liubing529@126.com; Teng Zhidong [Department of Mathematics, Xinjiang University, Urumqi 830046, Xinjiang (China); Liu Wanbo [Senior Middle School of Anshan Steel-Iron Company, Anshan 114034, Liaoning (China)

2007-01-15

153

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

154

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

155

Self-similarities of periodic structures for a discrete model of a two-gene system  

International Nuclear Information System (INIS)

We report self-similar properties of periodic structures remarkably organized in the two-parameter space for a two-gene system, described by two-dimensional symmetric map. The map consists of difference equations derived from the chemical reactions for gene expression and regulation. We characterize the system by using Lyapunov exponents and isoperiodic diagrams identifying periodic windows, denominated Arnold tongues and shrimp-shaped structures. Period-adding sequences are observed for both periodic windows. We also identify Fibonacci-type series and Golden ratio for Arnold tongues, and period multiple-of-three windows for shrimps. -- Highlights: ? The existence of noticeable periodic windows has been reported recently for several nonlinear systems. ? The periodic window distributions appear highly organized in two-parameter space. ? We characterize self-similar properties of Arnold tongues and shrimps for a two-gene model. ? We determine the period of the Arnold tongues recognizing a Fibonacci-type sequence. ? We explore self-similar features of the shrimps identifying multiple period-three structures.

2012-03-12

156

Periodicity in a delayed ratio-dependent predator-prey system with exploited term  

Directory of Open Access Journals (Sweden)

Full Text Available With the help of the coincidence degree and the related continuation theorem, we explore the existence of at least two periodic solutions of a delayed ratio-dependent predator-prey system with exploited term. Some easily verifiable sufficient criteria are established for the existence of at least two positive periodic solutions.

Li Zhai

2007-12-01

157

Systemic autonomic involvement in episodic cluster headache: a comparison between active and remission periods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study we compared systemic autonomic involvement in episodic cluster headache during active and silent periods. Seventeen patients were studied with sympathetic skin response, lying to standing test, Valsalva manoeuvre, deep breathing test and orthostatic hypotension evaluation. Each of them underwent these tests during active and silent periods. Values were then compared with normal controls. Our data show a parasympathetic, but not sympathetic,...

Meineri, P.; Pellegrino, G.; Rosso, M. G.; Grasso, E.

2005-01-01

158

Existence of Periodic Solutions of Linear Hamiltonian Systems with Sublinear Perturbation  

Directory of Open Access Journals (Sweden)

Full Text Available We investigate the existence of periodic solutions of linear Hamiltonian systems with a nonlinear perturbation. Under generalized Ahmad-Lazer-Paul type coercive conditions for the nonlinearity on the kernel of the linear part, existence of periodic solutions is obtained by saddle point theorems. A note on a result of Rabinowitz is also given.

Zhiqing Han

2010-01-01

159

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

CERN Multimedia

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

160

Periodic orbits in non-integrable hamiltoniam systems with two degrees of freedom  

International Nuclear Information System (INIS)

We present extensive numerical data concerning the periodics orbits of a non integrable two degrees of freedom hamiltoniam system. These periodics orbits form a one-parameter family and the data are displayed in a plot of energy x period. These orbits exhibit several kinds of bifurcations not predicted in the generic study by K.R. Meyer (Trans. Am. Math. Soc., 1970) due to the existence of symmetries in the hamiltonian. Using a perturbative treatment in the neighbourhood of the periodic trajectories, we analytically compute the effect of these symmetries in the bifurcations. These results are in perfect agreement with those obtained numerically. (author)

1987-01-01

 
 
 
 
161

Periodic solutions of nonlinear dynamical systems numerical computation, stability, bifurcation and transition to chaos  

CERN Document Server

Limit cycles or, more general, periodic solutions of nonlinear dynamical systems occur in many different fields of application. Although, there is extensive literature on periodic solutions, in particular on existence theorems, the connection to physical and technical applications needs to be improved. The bifurcation behavior of periodic solutions by means of parameter variations plays an important role in transition to chaos, so numerical algorithms are necessary to compute periodic solutions and investigate their stability on a numerical basis. From the technical point of view, dynamical systems with discontinuities are of special interest. The discontinuities may occur with respect to the variables describing the configuration space manifold or/and with respect to the variables of the vector-field of the dynamical system. The multiple shooting method is employed in computing limit cycles numerically, and is modified for systems with discontinuities. The theory is supported by numerous examples, mainly fro...

Reithmeier, Eduard

1991-01-01

162

System for Generation Long Streamflow Records for Study of Floods of Long Return Period. Phase II.  

Science.gov (United States)

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 ...

D. D. Franz B. A. Kraeger R. K. Linsley

1989-01-01

163

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

2009-08-01

164

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

International Nuclear Information System (INIS)

In this thesis, the possibility of controlling low- and high-dimensional chaotic systems by periodically driving an accessible system parameter is examined. This method has been carried out on several numerical systems and the MST Reversed Field Pinch. The numerical systems investigated include the logistic equation, the Lorenz equations, the Roessler equations, a coupled lattice of logistic equations, a coupled lattice of Lorenz equations, the Yoshida equations, which model tearing mode fluctuations in a plasma, and a neural net model for magnetic fluctuations on MST. This method was tested on the MST by sinusoidally driving a magnetic flux through the toroidal gap of the device. Numerically, periodic drives were found to be most effective at producing limit cycle behavior or significantly reducing the dimension of the system when the perturbation frequency was near natural frequencies of unstable periodic orbits embedded in the attractor of the unperturbed system. Several different unstable periodic orbits have been stabilized in this way for the low-dimensional numerical systems, sometimes with perturbation amplitudes that were less than 5% of the nominal value of the parameter being perturbed. In high-dimensional systems, limit cycle behavior and significant decreases in the system dimension were also achieved using perturbations with frequencies near the natural unstable periodic orbit frequencies. Results for the MST were not this encouraging, most likely because of an insufficient drive amplitude, the extremely high dimension of the plasma behavior, large amounts of noise, and a lack of stationarity in the transient plasma pulses

1998-01-01

165

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

166

The quasi-periodic stability condition (the KAM theorem) for partially-integrable systems  

CERN Document Server

Written with respect to an appropriate Poisson structure, a partially integrable Hamiltonian system is viewed as a completely integrable system with parameters. Then, the theorem on quasi-periodic stability in Ref. [1] (the KAM theorem) can be applied to this system.

Sardanashvily, G

2003-01-01

167

Time-reversal in dynamically-tuned zero-gap periodic systems  

CERN Multimedia

We show that short pulses propagating in zero-gap periodic systems can be reversed with 100% efficiency by using weak non-adiabatic tuning of the wave velocity at time-scales that can be much slower than the period. Unlike previous schemes, we demonstrate reversal of {\\em broadband} (few cycle) pulses with simple structures. Our scheme may thus open the way to time-reversal in a variety of systems for which it was not accessible before.

Sivan, Yonatan

2011-01-01

168

Research on anti-disturbance property of HFETRC period monitoring system  

International Nuclear Information System (INIS)

The anti-disturbance problem of the period monitoring system for test reactor critical assembly is mainly discussed and how to judge and search for the interference source using spotting experimental methods starting from the practical engineering without special equipment is introduced. So the electro-magnetic interference is removed. After finding out the reason, four measures are adopted to build up the anti-disturbance ability of the period monitoring system. (authors)

2006-01-01

169

The kinetics of quantum system with time-dependent periodic Hamiltonian  

International Nuclear Information System (INIS)

The kinetics of faintly non-ideal quantum system located in time-dependent periodic strong field is considered. The basis is introduced of quasi-energy states constructed with neglect to the inter system interaction. It is shown that in the indicated basis one can describe the system using the kinetic equation, that generalized the well-known Pauli equation.The system-thermostat interaction is taken into account. Possible types of system equilibrium are considered. (author). 6 refs

1994-01-01

170

Codimension two bifurcation of periodic vibro-impact and chaos of a dual component system  

International Nuclear Information System (INIS)

A two-degree-of-freedom vibro-impact system is considered. Dynamical behavior of the system, under the condition of codimension two bifurcation, is investigated by using qualitative analysis and numerical simulations. It is found that near by the point of codimension two bifurcation there exist not only supercritical and subcritical Hopf bifurcations of period 1 single-impact motions (1/1), but also Hopf bifurcation of period 2 two-impact motion occurs. Transition of different forms of 1/1 fixed points, near by the bifurcation point, is demonstrated, and different routes from period 1 single-impact motions to chaos are also discussed

2003-07-07

171

Periodic solutions for a two-species nonautonomous competition system with diffusion and impulses  

Energy Technology Data Exchange (ETDEWEB)

By re-estimating the upper bound of {integral}{sub 0}{sup {omega}}e{sup u{sub i}}{sup (t)}dt (i=1,2), we generalize a result about the existence of a positive periodic solution for a two-species nonautonomous patchy competition system with time delay. Based on that system, we consider the impulsive harvesting and stocking, and establish a two-species nonautonomous competition Lotka-Volterra system with diffusion and impulsive effects. With the continuation theorem of coincidence degree theory, we obtain the existence of a positive periodic solution for such a system. At last, two examples are given to demonstrate our results.

Dong Lingzhen [Department of Mathematics, Taiyuan University of Technology, Taiyuan 030024 (China)]. E-mail: linzhen_dong@yahoo.com.cn; Chen Lansun [Department of Applied Mathematics, Dalian University of Technology, Dalian 116023 (China); Shi Peilin [Department of Mathematics, Taiyuan University of Technology, Taiyuan 030024 (China)

2007-06-15

172

Periodic solutions for a two-species nonautonomous competition system with diffusion and impulses  

International Nuclear Information System (INIS)

By re-estimating the upper bound of ?0?eui(t)dt (i=1,2), we generalize a result about the existence of a positive periodic solution for a two-species nonautonomous patchy competition system with time delay. Based on that system, we consider the impulsive harvesting and stocking, and establish a two-species nonautonomous competition Lotka-Volterra system with diffusion and impulsive effects. With the continuation theorem of coincidence degree theory, we obtain the existence of a positive periodic solution for such a system. At last, two examples are given to demonstrate our results

2007-06-01

173

Localization of periodic orbits of the Roessler system under variation of its parameters  

International Nuclear Information System (INIS)

The localization problem of compact invariant sets of the Roessler system is considered in this paper. The main interest is attracted to a localization of periodic orbits. We establish a number of algebraic conditions imposed on parameters under which the Roessler system has no compact invariant sets contained in half-spaces z > 0; z < 0 and in some others. We prove that if parameters (a, b, c) of the Roessler system are such that this system has no equilibrium points then it has no periodic orbits as well. In addition, we give localization conditions of compact invariant sets by using linear functions and one quadratic function

2007-08-01

174

Stable 1 2 Resonant Periodic Orbits in Elliptic Three-Body Systems  

CERN Document Server

The results of an extensive numerical study of the periodic orbits of planar, elliptic restricted three-body planetary systems consisting of a star, an inner massive planet and an outer mass-less body in the external 1:2 mean-motion resonance are presented. Using the method of differential continuation, the locations of the resonant periodic orbits of such systems are identified and through an extensive study of their phase-parameter space, it is found that the majority of the resonant periodic orbits are unstable. For certain values of the mass and the orbital eccentricity of the inner planet, however, stable periodic orbits can be found. The applicability of such studies to the 1:2 resonance of the extrasolar planetary system GJ876 is also discussed.

Haghighipour, N; Varadi, F; Moore, W B; Haghighipour, Nader; Couetdic, Jocelyn; Varadi, Ferenc; Moore, William B.

2003-01-01

175

V456 Ophiuchi and V490 Cygni: Systems with the shortest apsidal-motion periods  

CERN Document Server

Our main aim is the first detailed analysis of the two eclipsing binaries V456 Oph and V490 Cyg. The system V456 Oph has been studied both photometrically via an analysis of its light curve observed by the INTEGRAL/OMC and by the period analysis of all available times of minima. V490 Cyg has been studied by means of a period analysis only. Many new times of minima for both systems have recently been observed and derived. This allows us for the first time to study in detail the processes that affect both binaries. The main result is the discovery that both systems have eccentric orbits. For V456 Oph we deal with the eccentric eclipsing binary system with the shortest orbital period known (about 1.016 day), while the apsidal motion period is about 23 years. V490 Cyg represents the eclipsing system with the shortest apsidal motion period (about 18.8 years only). The two components of V456 Oph are probably of spectral type F. We compare and discuss the V456 Oph results from the light curve and the period analysis...

Zasche, P; 10.1051/0004-6361/201015720

2011-01-01

176

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

2009-01-01

177

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 r...

2008-01-01

178

Universality and fractal dimension of mode locking structure in systems with competing periodicities  

Energy Technology Data Exchange (ETDEWEB)

We are concerned with the properties of physical systems with competing periodicities. Two very different situations are considered. In the first case the competition is between two periods in time, or two frequencies, in a system which is at the verge of entering into a chaotic state. In the second case the competition is between two periods in space. In both cases there is a nonlinear coupling which tend to lock the two periods together. An example of a system of the first type is a driven damped pendulum perturbed by an external oscillating force. In the absence of the periodic force the pendulum will oscillate, or rotate with a frequency of its own. If the coupling is weak the frequencies will lock only if the unperturbed frequencies are related to each other through almost rational numbers. If the coupling is stronger there will be an increased tendence towards locking. At some critical strength the modes may always be locked so that the resulting frequency is always a rational fraction of the frequency of the external perturbation. If the coupling is even stronger the motion may become chaotic, with no single basic frequency. In the second case one has a competition between the period, or wave vector of the spatially ordered structure, such as a spin-density wave, and the periodicity of the lattice on which the system is defined. A specific model of this type is the axial next-nearest-neighbor Ising (ANNNI) model. For some values of the parameters the magnetic structure has a period of its own, not related to the periodicity of the underlying lattice. In other regimes of the phase diagram, where the effective coupling is stronger, the resulting structure is always commensurable with the lattice. As a specific example we consider a simple one-dimensional Ising model with long range antiferromagnetic interactions.

Bak, P.

1983-01-01

179

On periodic solutions of parametrically excited complex non-linear dynamical systems  

Science.gov (United States)

An approximate analytical method, based on the generalized averaging method is extended to study periodic solutions of parametrically excited complex non-linear dynamical systems. It is well known that a great many problems of applied sciences often lead to the study of these dynamical systems. Our analytical approach provides us with specific values for the parameters of these dynamical systems for which such periodic solutions exist. An example which is related to rotor dynamics and spherical pendulum with vertically oscillating support is considered to illustrate this approach. Analytical results on this example are compared with numerical ones and excellent agreement is found between them.

Mahmoud, Gamal M.; Aly, Shaban A. H.

2000-04-01

180

Influence of external periodic and non-linear factors upon stability of economic systems ??????? ??????? ????????????? ? ?????????? ???????? ?? ???????????? ????????????? ??????  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The article conducts a study of influence of periodic effect upon economic systems. It shows a danger of the resonance case when frequency of external periodic effect on the system tends to its own frequency of vibrations near the state of equilibrium. In this case, the amplitude of vibrations of the system becomes proportional to time and grows with it. Account of impacts, proportional to the rate of shift from the state of equilibrium, results in limitation of growth of the amplitude of vib...

Kostenko Elena; Kuznichenko Vladimir M.; Lapshyn Vladimir I.

2013-01-01

 
 
 
 
181

Hyperchaotic behavior in a non-autonomous unified chaotic system with continuous periodic switch  

International Nuclear Information System (INIS)

This paper further investigates a non-autonomous unified chaotic system with continuous periodic switch found in [Lu J, Wu X. A unified chaotic system with continuous periodic switch. Chaos, Solitons and Fractals 2004;20:245-51], which is another different realization for the unified chaotic system developed in [Lue J, Chen G, Cheng D, Celikovsky S. Bridge the gap between the Lorenz system and the Chen system, Int J Bifurcat Chaos 2002;12:2917-26]. Hyperchaotic behavior is discovered within some system parameter range, which has not yet been reported before. The detailed behaviors of this system are not only demonstrated by computer simulations but also verified with Lyapunov exponents spectrum, bifurcation analysis and Poincare maps

2007-05-01

182

Laplace transformations of hydrodynamic type systems in Riemann invariants periodic sequences  

CERN Multimedia

The conserved densities of hydrodynamic type system in Riemann invariants satisfy a system of linear second order partial differential equations. For linear systems of this type Darboux introduced Laplace transformations, generalising the classical transformations in the scalar case. It is demonstrated that Laplace transformations can be pulled back to the transformations of the corresponding hydrodynamic type systems. We discuss periodic Laplace sequences of with the emphasize on the simplest nontrivial case of period 2. For 3-component systems in Riemann invariants a complete description of closed quadruples is proposed. They turn to be related to a special quadratic reduction of the (2+1)-dimensional 3-wave system which can be reduced to a triple of pairwize commuting Monge-Ampere equations. In terms of the Lame and rotation coefficients Laplace transformations have a natural interpretation as the symmetries of the Dirac operator, associated with the (2+1)-dimensional n-wave system. The 2-component Laplace...

Ferapontov, E V

1997-01-01

183

Global Exponential Stability of Almost Periodic Solution for A Large Class of Delayed Dynamical Systems  

CERN Multimedia

Research of delayed neural networks with variable self-inhibitions, inter-connection weights, and inputs is an important issue. %In the real world, self-inhibitions, %inter-connection weights, and inputs should vary through time. In In this paper, we discuss a large class of delayed dynamical systems with almost periodic self-inhibitions, inter-connection weights, and inputs. This model is universal and includes delayed systems with time-varying delays, distributed delays as well as combination of both. We prove that under some mild conditions, the system has a unique almost periodic solution, which is globally exponentially stable. We propose a new approach, which is independent of existing theory concerning with existence of almost periodic solution for dynamical systems.

Lu, W; Lu, Wenlian; Chen, Tianping

2006-01-01

184

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

2008-04-01

185

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

186

Existence and global attractivity of positive periodic solution for competition-predator system with variable delays  

International Nuclear Information System (INIS)

In this paper, Lotka-Volterra competition-predator system with variable delays is considered. Some sufficient conditions ensuring the existence and global attractivity of periodic solution for this system are obtained by using coincidence degree theory and Lyapunov functional method. An example is also worked out to demonstrate the advantages of our results

2006-07-01

187

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

188

Global attractivity of almost periodic solutions for competitive Lotka-Volterra diffusion system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, two competitive Lotka-Volterra populations in the two-patch-system with diffusion are considered. Each of the two spiecies can diffuse indepently and discretely between its in intrapatch and interpatch. By means of constructing Liapunov function, under moderate condition, the system has a unique almost periodic solution and which is asymptotically stable and globally attractive .

Muhammadhaji, Ahmadjan; Teng, Zhidong; Rehim, Mehbuba

2013-01-01

189

Existence and global attractivity of positive periodic solution for competition-predator system with variable delays  

Energy Technology Data Exchange (ETDEWEB)

In this paper, Lotka-Volterra competition-predator system with variable delays is considered. Some sufficient conditions ensuring the existence and global attractivity of periodic solution for this system are obtained by using coincidence degree theory and Lyapunov functional method. An example is also worked out to demonstrate the advantages of our results.

Zhao Hongyong [Department of Mathematics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)]. E-mail: hongyongz@126.com; Ding Nan [Department of Mathematics, Xinjiang Normal University, Urumqi 830054 (China)

2006-07-15

190

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

2008-08-01

191

Quasilinearization for the periodic boundary value problem for systems of impulsive differential equations  

Directory of Open Access Journals (Sweden)

Full Text Available The method of generalized quasilinearization for the system of nonlinear impulsive differential equations with periodic boundary conditions is studied. As a byproduct, the result for the system without impulses can be obtained, which is a new result as well.

S. G. Hristova

2006-01-01

192

Detecting unstable periodic orbits embedded in chaotic systems using the simplex method  

Science.gov (United States)

This paper proposes an approach for detecting unstable periodic orbits embedded in chaotic systems by using the simplex method. The simplex algorithm is easily implemented and does not require the derivatives of the function to be optimized. As a result, it is also applicable to chaotic systems with discontinuities or in which functions contain noise.

Fuh, Chyun-Chau

2009-04-01

193

Stability and Periodic Solution to Competitive Lotka-Volterra System with diffusion and Infinite Distributed Delay  

Directory of Open Access Journals (Sweden)

Full Text Available A competitive Lotka-volterra systemwith diffusion and infinite distributed delays is investigated. It is shown that the globally asymptotically stable trivial solution, when r1(ai>=0,(i=1,2,the globally asymptotically stable semi-trivial periodic solution(r1(t,x,,and 0,r2(t,x when p1(a1=0,p1(a2<0 of the models byconstruction of a pair of upper and lower solution (u1,u2,(0,0of parabolic periodic system (aui(t,x/at-Aiui(t,x=ui(t,x[ai(t,x-bi(t,xui(t,x],and in the use of eigenvalue theory and comparison principle. A T-periodic series are established by using the monotone iteration technique. It was obtained that the systems have a pair of periodic positive solutions with respect to every nonnegative initial function.

XU Tian-hua

2009-06-01

194

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.

2009-03-01

195

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.

Xiang X

2008-01-01

196

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

2013-06-01

197

Stochastic Responses of the Stable Period-$p$ Orbits in One-Dimensional Noisy Map Systems  

CERN Multimedia

We analytically derive the correlation functions of the stochastic response of period-$p$ orbits in a generic one-dimensional map system under the influence of weak external, additive white noise. Two approaches, a recurrence scheme and a path integral method, are provided. Beside the supercycle, we recognise that the fluctuations on each elements of the period-$p$ orbits are colored noise which have non-vanishing time correlation. The results also indicate that the stochastic responses will be stationary after a large number of period-$p$ iterations. The analytical results are confirmed by numerical simulations.

Wang, T N; Su, H T; Lin, W F; Chern, J L; Chen, C C; Wang, Tian-Nan; Hsu, Rue-Ron; Su, Han-Tzong; Lin, Wei-Fu; Chern, Jyh-Long; Chen, Chia-Chu

1997-01-01

198

Tuning the period of square-wave oscillations for delay-coupled optoelectronic systems  

Science.gov (United States)

We analyze the response of two delay-coupled optoelectronic oscillators. Each oscillator operates under its own delayed feedback. We show that the system can display square-wave periodic solutions that can be synchronized in phase or out of phase depending on the ratio between self- and cross-delay times. Furthermore, we show that multiple periodic synchronized solutions can coexist for the same values of the fixed parameters. As a consequence, it is possible to generate square-wave oscillations with different periods by just changing the initial conditions.

Martínez-Llinàs, Jade; Colet, Pere; Erneux, Thomas

2014-04-01

199

Analysis and enhancement of torsional vibration stopbands in a periodic shaft system  

Science.gov (United States)

The band structure and the enhancement of stopbands in a periodic shaft are investigated. The band structures created by a hard ring and a locally resonant (LR) ring are studied first. A uniform method for analysing the band structures of periodic shafts with various attached structures is proposed. Furthermore, the enhancement of the stopbands is discussed. The properties of a shaft with a hard ring and an LR ring in different positions are studied, and a wide, combined gap is created at low frequencies. Additionally, continuous beams are also introduced to enhance the stopbands. Some helpful methods for analysis, prediction and increasing the width of stopbands in a periodic shaft system are provided.

Song, Yubao; Wen, Jihong; Yu, Dianlong; Wen, Xisen

2013-04-01

200

Critical periods of vulnerability for the developing nervous system: evidence from humans and animal models.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Vulnerable periods during the development of the nervous system are sensitive to environmental insults because they are dependent on the temporal and regional emergence of critical developmental processes (i.e., proliferation, migration, differentiation, synaptogenesis, myelination, and apoptosis). Evidence from numerous sources demonstrates that neural development extends from the embryonic period through adolescence. In general, the sequence of events is comparable among species, although t...

Rice, D.; Barone, S.

2000-01-01

 
 
 
 
201

Existence and global stability of positive periodic solutions of a discrete delay competition system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The existence and the global stability of positive periodic solutions of a discrete competition model is studied. The model incorporates time delays and allows for a fluctuating environment. By means of some standard procedures of the topological degree method and the construction of a suitable Lyapunov function, sufficient conditions are obtained to ensure the existence and the global stability of positive periodic solutions of the above systems.

Hai-Feng Huo; Wan-Tong Li

2003-01-01

202

Existence and global stability of positive periodic solutions of a discrete delay competition system  

Directory of Open Access Journals (Sweden)

Full Text Available The existence and the global stability of positive periodic solutions of a discrete competition model is studied. The model incorporates time delays and allows for a fluctuating environment. By means of some standard procedures of the topological degree method and the construction of a suitable Lyapunov function, sufficient conditions are obtained to ensure the existence and the global stability of positive periodic solutions of the above systems.

Wan-Tong Li

2003-07-01

203

Period ratios in multi-planetary systems discovered by Kepler are consistent with planet migration  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Kepler planet candidates are an interesting testbed for planet formation scenarios. We present results from N-body simulations of multi-planetary systems that resemble those observed by Kepler. We add both smooth (Type I/II) and stochastic migration forces. The observed period ratio distribution is inconsistent with either of those two scenarios on its own. However, applying both stochastic and smooth migration forces to the planets simultaneously results in a period r...

Rein, Hanno

2012-01-01

204

Classical and quantum mechanical aspects of the nonlinear dynamics of periodically driven systems  

International Nuclear Information System (INIS)

The present thesis treats two aspects from the mentioned circle of themes. First we discuss in chapter 2 the foundation of adiabatic motion and the quantum holonomy in systems, which are described by periodically time-dependent Hamilton operators, connected with this. In difference to these purely quantum mechanical considerations the 3. chapter contains a classical study on the nonlinear dynamics of periodically driven anharmonic oscillators. (orig./HSI)

1990-01-01

205

Couplonics Of Cyclic Ternary Systems: From Coupled Periodic Waveguides To Discrete Photonic Crystals  

Directory of Open Access Journals (Sweden)

Full Text Available In the context of coupled periodic waveguides, "couplonics" refers to the rigorous equivalence between continuous wave coupling and localized interactions. We extend it here to a cyclic ternary system, looked upon as the simplest discrete photonic crystal with actual periodic boundary conditions. A linear decomposition on a supermode basis enables one to reduce the original sixwave problem to three independent two-wave distributed Bragg reflectors (or 1D PC.

Yann G. Boucher

2013-02-01

206

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

207

Period Change Similarities among the RR Lyrae Variables in Oosterhoff I and Oosterhoff II Globular Systems  

CERN Document Server

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 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 $\\omega$~ 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 HB stars that spent their ZAHB phase on the blue side of the instability strip. This ...

Kunder, Andrea; Stetson, Peter B; Bono, Giuseppe; Nemec, James M; de Propris, Roberto; Monelli, Matteo; Cassisi, Santi; Andreuzzi, Gloria; Dall'Ora, Massimo; Di Cecco, Alessandra; Zoccali, Manuela

2010-01-01

208

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

2010-04-01

209

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

2006-09-01

210

On the Planetary Orbital Period Ratio Distribution In Multiple Planet Systems  

Science.gov (United States)

Many multiple planet systems have been found by both radial velocity (RV) and transit surveys, such as the Kepler mission. Period ratio distribution of these planet candidates show that they do not prefer to be in or near Mean Motion Resonance (MMR). Nevertheless, there are small but significant excesses of candidate pairs both spaced slightly exterior to exact resonance, particular near the first order of MMR, such as 2:1 and 3:2. Here, we first review recent observational constraints on these multiple transiting systems and theoretical models, which attempt to understand their period ratio distributions. Then we identify a statistical effect based on an intrinsic asymmetry associated with MMR, and find it play an important role in shaping the period ratio distribution near MMR. Last but least, we also find such an intrinsic asymmetry is existing in asteroids of our solar system.

Xie, Ji-Wei

2014-04-01

211

The origin of Saturn's magnetic periodicities: Northern and southern current systems  

Science.gov (United States)

recent survey by Andrews et al. (2012) of the separate northern and southern ~10.7 h periodic magnetic signals in Saturn's magnetosphere limits very much their governing current systems. The existence of signals with pure or close to pure northern or southern periods in respective polar caps taken with the relatively narrow bandwidth of the signals indicates that the actual periodicities are imposed independently from northern and southern polar regions, i.e., the open field line regions. Field-aligned currents must flow on the boundaries of these regions to exclude signals from the other hemisphere. Equatorward of the polar cap, on closed magnetic shells, there are distinct north and south "cam" source currents, the distinction being made clear by a difference in polarization. We outline the consequences for the governing current systems and the implications for sustaining the energy and power dissipation in the system.

Southwood, D. J.; Cowley, S. W. H.

2014-03-01

212

Pattern formation in liquid-vapor systems under periodic potential and shear  

Science.gov (United States)

In this paper the phase behavior and pattern formation in a sheared nonideal fluid under a periodic potential is studied. An isothermal two-dimensional formulation of a lattice Boltzmann scheme for a liquid-vapor system with the van der Waals equation of state is presented and validated. Shear is applied by moving walls and the periodic potential varies along the flow direction. A region of the parameter space, where in the absence of flow a striped phase with oscillating density is stable, will be considered. At low shear rates the periodic patterns are preserved and slightly distorted by the flow. At high shear rates the striped phase loses its stability and traveling waves on the interface between the liquid and vapor regions are observed. These waves spread over the whole system with wavelength only depending on the length of the system. Velocity field patterns, characterized by a single vortex, will also be shown.

Coclite, A.; Gonnella, G.; Lamura, A.

2014-06-01

213

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

214

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

2004-01-01

215

Time-averaged properties of unstable periodic orbits and chaotic orbits in ordinary differential equation systems.  

Science.gov (United States)

It has recently been found in some dynamical systems in fluid dynamics that only a few unstable periodic orbits (UPOs) with low periods can give good approximations to the mean properties of turbulent (chaotic) solutions. By employing three chaotic systems described by ordinary differential equations, we compare time-averaged properties of a set of UPOs and those of a set of segments of chaotic orbits. For every chaotic system we study, the distributions of a time average of a dynamical variable along UPOs with lower and higher periods are similar to each other and the variance of the distribution is small, in contrast with that along chaotic segments. The distribution seems to converge to some limiting distribution with nonzero variance as the period of the UPO increases, although that along chaotic orbits inclines to converge to a delta -like distribution. These properties seem to lie in the background of why only a few UPOs with low periods can give good mean statistical properties in dynamical systems in fluid dynamics. PMID:19257096

Saiki, Yoshitaka; Yamada, Michio

2009-01-01

216

Stellar Rotation-Planetary Orbit Period Commensurability in the HAT-P-11 System  

Science.gov (United States)

A number of planet host stars have been observed to rotate with a period equal to an integer multiple of the orbital period of their close planet. We expand this list by analyzing Kepler data of HAT-P-11 and finding a period ratio of 6:1. In particular, we present evidence for a long-lived spot on the stellar surface that is eclipsed by the planet in the same position four times, every sixth transit. We also identify minima in the out-of-transit light curve and confirm that their phase with respect to the stellar rotation is mostly stationary for the 48 month time frame of the observations, confirming the proposed rotation period. For comparison, we apply our methods to Kepler-17 and confirm the findings of Bonomo & Lanza that the period ratio is not exactly 8:1 in that system. Finally, we provide a hypothesis on how interactions between a star and its planet could possibly result in an observed commensurability for systems where the stellar differential rotation profile happens to include a period at some latitude that is commensurable to the planetary orbit.

Béky, Bence; Holman, Matthew J.; Kipping, David M.; Noyes, Robert W.

2014-06-01

217

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 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

1981-01-29

218

Predictions of quasi-periodic and chaotic motions in nonlinear Hamiltonian systems  

International Nuclear Information System (INIS)

In this paper, the mechanism of chaotic motion in nonlinear Hamiltonian systems is discussed based on the KAM theory and resonance overlap criterion. The internal resonances and the corresponding chaotic motions are determined analytically for weak interactions. A numerical method based on the energy spectrum is presented for prediction of quasi-periodic and chaotic motions in nonlinear Hamiltonian systems. The presented numerical method can be applied to integrable, nonlinear Hamiltonian systems with many degrees of freedom. A 2-DOF integrable, nonlinear Hamiltonian system is investigated as an example for demonstration of the procedure to numerically determine the chaotic motion in nonlinear Hamiltonian systems. Finally, the Poincare mapping surfaces of chaotic motions for such nonlinear Hamiltonian systems are illustrated. The phase planes, displacement surfaces (or potential domains), and the velocity surfaces (or kinetic energy domains) for the chaotic and quasi-periodic motions are illustrated. The analytical estimates of regular and chaotic motions in nonlinear Hamiltonian systems need to be further investigated. The mathematical theory should be developed for a better prediction of chaotic and quasi-periodic motions in nonlinear Hamiltonian systems with many degrees of freedom

2006-05-01

219

XVIII Mendeleev congress on general and applied chemistry. Summaries of reports in five volumes. Volume 3. Actual problems of chemical industry, estimation of technical risks. Physicochemical basis of rational use of natural and technogenic resources. Chemical aspects of modern energetics. Petrochemistry, petroleum processing and catalysis  

International Nuclear Information System (INIS)

The 3 volume of the XVIII Mendeleev congress on general and applied chemistry includes summaries of reports, lectures and stand information on achievements and prospects of chemical science in such areas as chemical industry, physicochemical basis of rational use of natural and technogenic raw materials, chemical aspects of modern energetics, petrochemistry, petroleum processing and catalysis

2007-09-23

220

Nonlinearity and periodic solution of a standard-beam balance oscillation system  

International Nuclear Information System (INIS)

We present the motion equation of the standard-beam balance oscillation system, whose beam and suspensions, compared with the compound pendulum, are connected flexibly and vertically. The nonlinearity and the periodic solution of the equation are discussed by the phase-plane analysis. We find that this kind of oscillation can be equivalent to a standard-beam compound pendulum without suspensions; however, the equivalent mass centre of the standard beam is extended. The derived periodic solution shows that the oscillation period is tightly related to the initial pivot energy and several systemic parameters: beam length, masses of the beam, and suspensions, and the beam mass centre. A numerical example is calculated. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

2012-06-01

 
 
 
 
221

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

CERN Document Server

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

222

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

1997-01-01

223

The periodically pulsed mode of operation of magnet systems in particle accelerators  

International Nuclear Information System (INIS)

Since in many applications in particle accelerator technology the beam duty factor, defined by the ratio of beam pulse length to the pulse to pulse period, is very small- typically in the order of 10"-_3 to 10"-_9 - it is interesting to operate the beam optical magnetic system in the periodically pulsed mode as well. Thus, by reducing the average Ohmic losses, it is possible to save energy and material. The pulsed mode of operation of magnet systems is especially adapted to those of linear accelerators and their beam transport systems, since linear accelerators are exclusively operated in this mode. But it is equally suitable for transport systems between cyclic accelerators and large storage rings as they are under development at present. (orig./WL)

1980-01-01

224

Coexistence of unbounded and periodic solutions to planar systems at resonance  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We provide a new sufficient condition for the coexistence of periodic and unbounded solutions to a planar differential system at resonance. The proof is performed by using a result on the existence of unbounded orbits of mappings in ${\\bf R}^2$}

Capietto, Anna; Dambrosio, Walter

2008-01-01

225

A New Method for Studying the Periodic System Based on a Kohonen Neural Network  

Science.gov (United States)

A new method for studying the periodic system is described based on the combination of a Kohonen neural network and a set of chemical and physical properties. The classification results are directly shown in a two-dimensional map and easy to interpret. This is one of the major advantages of this approach over other methods reported in the…

Chen, David Zhekai

2010-01-01

226

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

227

Existence of Positive Periodic Solutions of a Lotka-Volterra System with Multiple Time Delays  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, a class of Lotka-Volterra system with multiple time delays is considered. By using the continuation theoremof coincidence degree theory, we derive a set of easily verifiable sucient conditions that guarantees the existence of atleast a positive periodic solution.

Changjin Xu; Maoxin Liao

2010-01-01

228

Existence of Positive Periodic Solutions of a Lotka-Volterra System with Multiple Time Delays  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, a class of Lotka-Volterra system with multiple time delays is considered. By using the continuation theoremof coincidence degree theory, we derive a set of easily verifiable sucient conditions that guarantees the existence of atleast a positive periodic solution.

Changjin Xu

2010-01-01

229

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.

Yongkun Li

2011-01-01

230

Global Clock, Physical Time Order and Pending Period Analysis in Multiprocessor Systems  

CERN Multimedia

In multiprocessor systems, various problems are treated with Lamport's logical clock and the resultant logical time orders between operations. However, one often needs to face the high complexities caused by the lack of logical time order information in practice. In this paper, we utilize the \\emph{global clock} to infuse the so-called \\emph{pending period} to each operation in a multiprocessor system, where the pending period is a time interval that contains the performed time of the operation. Further, we define the \\emph{physical time order} for any two operations with disjoint pending periods. The physical time order is obeyed by any real execution in multiprocessor systems due to that it is part of the truly happened operation orders restricted by global clock, and it is then proven to be independent and consistent with traditional logical time orders. The above novel yet fundamental concepts enables new effective approaches for analyzing multiprocessor systems, which are named \\emph{pending period analy...

Chen, Yunji; Hu, Weiwu

2009-01-01

231

Periodic dynamics of delayed Lotka–Volterra competition systems with discontinuous harvesting policies via differential inclusions  

International Nuclear Information System (INIS)

Highlights: • A more practical form of harvesting management policy (DHP) has been proposed. • We analyze the periodic dynamics of a class of discontinuous and delayed Lotka–Volterra competition systems. • We present a new method to obtain the existence of positive periodic solutions via differential inclusions. • The global convergence in measure of harvesting solution is discussed. -- Abstract: This paper considers a general class of delayed Lotka–Volterra competition systems where the harvesting policies are modeled by discontinuous functions or by non-Lipschitz functions. By means of differential inclusions theory, cone expansion and compression fixed point theorem of multi-valued maps and nonsmooth analysis theory with generalized Lyapunov approach, a series of useful criteria on existence, uniqueness and global asymptotic stability of the positive periodic solution is established for the delayed Lotka–Volterra competition systems with discontinuous right-hand sides. Moreover, the global convergence in measure of harvesting solution is discussed. Our results improve and extend previous works on periodic dynamics of delayed Lotka–Volterra competition systems with not only continuous or even Lipschitz continuous but also discontinuous harvesting functions. Finally, we give some corollaries and numerical examples to show the applicability and effectiveness of the proposed criteria

2013-09-01

232

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

2013-07-01

233

Existence and multiplicity of positive periodic solutions for first-order singular systems with impulse effects  

Directory of Open Access Journals (Sweden)

Full Text Available In this article, we consider the existence and multiplicity of positive periodic solutions for a first-order singular system with impulse effects. The proof of our main result is based on Krasnoselskii's fixed point theorem in a cone.

Bian-Xia Yang

2013-05-01

234

Three periodic solutions to an eigenvalue problem for a class of second-order Hamiltonian systems  

Directory of Open Access Journals (Sweden)

Full Text Available We establish a multiplicity result to an eigenvalue problem related to second-order Hamiltonian systems. Under new assumptions, we prove the existence of an open interval of positive eigenvalues in which the problem admits three distinct periodic solutions.

Giuseppe Cordaro

2003-12-01

235

Global search of non-linear systems periodic solutions: A rotordynamics application  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Introducing non-linearities into models contributes towards a better reality description but leads to systems having multiple solutions. It is then legitimate to look for all the solutions of such systems, that is to have a global analysis approach. However no effective method can be found in literature for systems described by more than two or three degrees of freedom. We propose in this paper a way to find all T-periodic solutions--where T is known--of a non-linear dynamical system. This me...

Sarrouy, Emmanuelle; Thouverez, Fabrice

2010-01-01

236

Explicit Soliton and Periodic Solutions to Three-Wave System with Quadratic and Cubic Nonlinearities  

International Nuclear Information System (INIS)

Lie group theoretical method and the equation of the Jacobi elliptic function are used to study the three wave system that couples two fundamental frequency (FF) and a single second harmonic (SH) one by competing ?(2) (quadratic) and ?(3) (cubic) nonlinearities and birefringence. This system shares some of the nice properties of soliton system. On the phase-locked condition, we obtain large families of analytical solutions as the soliton, kink and periodic solutions of this system. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

2011-04-15

237

Adaptive estimation and control of unstable periodic dynamics in excitable biological systems  

CERN Multimedia

Dynamical control of excitable biological systems is often complicated by the difficult and unreliable task of pre-control identification of unstable periodic orbits (UPOs). Here we show that, for both chaotic and nonchaotic systems, UPOs can be located, and their dynamics characterized, during control. Tracking of system nonstationarities emerges naturally from this approach. Such a method is potentially valuable for the control of excitable biological systems, for which pre-control UPO identification is often impractical and nonstationarities (natural or stimulation-induced) are common.

Christini, D J; Christini, David J.; Kaplan, Daniel T.

1999-01-01

238

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

239

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Baruteau, Clement; Papaloizou, John C. B.

2013-01-01

240

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

 
 
 
 
241

Dynamic scheduling of periodic skippable tasks in an overloaded real-time system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The need for supporting dynamic real-time environments where changes in workloads may occur requires a scheduling framework that explicitly addresses overload conditions, allows the system to achieve graceful degradation and supports a mechanism capable of determining the load to be shed from the system to handle the overload. In applications ranging from video reception to air-craft control, tasks enter periodically and have response time constraints, but missing a deadline is acceptable, pr...

2008-01-01

242

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 statistical analysis predicts ~17 such pairs. For orbital periods of the inner planet that are less than three days, the minimum period ratio ...

Steffen, Jason H.; Farr, Will

2013-01-01

243

Orbital periods and Accretion disc structure of four AM CVn systems  

CERN Multimedia

Phase-resolved spectroscopy of four AM CVn systems obtained with the William Herschel Telescope and the Gran Telescopio de Canarias (GTC) is presented. SDSS\\,J120841.96+355025.2 was found to have an orbital period of 52.96$\\pm$0.40\\,min and shows the presence of a second bright spot in the accretion disc. The average spectrum contains strong Mg\\,{\\sc i} and Si\\,{\\sc i/ii} absorption lines most likely originating in the atmosphere of the accreting white dwarf. SDSS\\,J012940.05+384210.4 has an orbital period of 37.555$\\pm$0.003 min. The average spectrum shows the Stark broadened absorption lines of the DB white dwarf accretor. The orbital period is close to the previously reported superhump period of 37.9\\,min. Combined, this results in a period excess $\\epsilon$=0.0092$\\pm$0.0054 and a mass ratio $q=0.031\\pm$0.018. SDSS\\,J164228.06+193410.0 displays an orbital period of 54.20$\\pm$1.60\\,min with an alias at 56.35\\,min. The average spectrum also shows strong Mg\\,{\\sc i} absorption lines, similar to SDSS\\,J120841...

Kupfer, T; Levitan, D; Steeghs, D; Marsh, T R; Rutten, R G M; Nelemans, G

2013-01-01

244

Using the isotropic periodic sum method to calculate long-range interactions of heterogeneous systems.  

Science.gov (United States)

Isotropic periodic sum (IPS) is a method for the calculation of long-range interactions in molecular simulation based on the homogeneity of simulation systems. Three IPS models, 3D IPS, 2D IPS, and 1D IPS have been developed for three common types of homogeneous systems. Based on the fact that 3D IPS can well describe the long-range interactions of a heterogeneous system if a local region larger than the homogeneity scale is used, this work presents a method based on 3D IPS to calculate long-range interactions for all kinds of simulation systems, including homogeneous, heterogeneous, and finite systems. Unlike the original 3D IPS method that uses a local region defined by the cutoff distance, this method uses a local region larger than that defined by the cutoff distance to reach the homogeneity scale. To efficiently calculate interactions within such a large local region, this method split long-range interactions into two parts, a cutoff part and a long-range part. The cutoff part is calculated by summing over atom pairs within a cutoff range (about 10 A), and the long-range part is calculated using the discrete fast Fourier transform (DFFT) technique. This method is applied to electrostatic and van der Waals interactions for both periodic and non-periodic systems. Example simulations demonstrate that this method can accurately and efficiently calculate long-range interactions for molecular simulation. PMID:19045184

Wu, Xiongwu; Brooks, Bernard R

2008-10-21

245

Orbital periods of cataclysmic variables identified by the SDSS. VII. Four new eclipsing systems  

CERN Document Server

We present photometry of nine cataclysmic variable stars identified by the Sloan Digital Sky Survey, aimed at measuring the orbital periods of these systems. Four of these objects show deep eclipses, from which we measure their orbital periods. The light curves of three of the eclipsing systems are also analysed using the LCURVE code, and their mass ratios and orbital inclinations determined. SDSS J075059.97+141150.1 has an orbital period of 134.1564 +/- 0.0008 min, making it a useful object with which to investigate the evolutionary processes of cataclysmic variables. SDSS J092444.48+080150.9 has a period of 131.2432 +/- 0.0014 min and is probably magnetic. The white dwarf ingress and egress phases are very deep and short, and there is no clear evidence that this object has an accretion disc. SDSS J115207.00+404947.8 and SDSS J152419.33+220920.1 are nearly identical twins, with periods of 97.5 +/- 0.4 and 93.6 +/- 0.5 min and mass ratios of 0.14 +/- 0.03 and 0.17 +/- 0.03, respectively. Their eclipses have w...

Southworth, John; Gansicke, B T; Pyrzas, S

2009-01-01

246

Anomalous edge states and the bulk-edge correspondence for periodically-driven two dimensional systems  

DEFF Research Database (Denmark)

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 â??anomalousâ? spectra that arise in driven systems. Possibilities for realizing these phenomena in solid-state and cold-atomic systems are discussed.

Rudner, Mark Spencer; Lindner, Netanel

2013-01-01

247

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

International Nuclear Information System (INIS)

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

2003-12-01

248

Orbital periods and accretion disc structure of four AM CVn systems  

Science.gov (United States)

Phase-resolved spectroscopy of four AM CVn systems obtained with the William Herschel Telescope and the Gran Telescopio de Canarias is presented. SDSS J120841.96+355025.2 was found to have an orbital period of 52.96 ± 0.40 min and shows the presence of a second bright spot in the accretion disc. The average spectrum contains strong Mg I and Si I/II absorption lines most likely originating in the atmosphere of the accreting white dwarf. SDSS J012940.05+384210.4 has an orbital period of 37.555 ± 0.003 min. The average spectrum shows the Stark-broadened absorption lines of the DB white dwarf accretor. The orbital period is close to the previously reported superhump period of 37.9 min. Combined, this results in a period excess ? = 0.0092 ± 0.0054 and a mass ratio q = 0.031 ± 0.018. SDSS J164228.06+193410.0 displays an orbital period of 54.20 ± 1.60 min with an alias at 56.35 min. The average spectrum also shows strong Mg I absorption lines, similar to SDSS J120841.96+355025.2. SDSS J152509.57+360054.50 displays a period of 44.32 ± 0.18 min. The overall shape of the average spectrum is more indicative of shorter period systems in the 20-35 min range. The accretor is still clearly visible in the pressure-broadened absorption lines most likely indicating a hot donor star and/or a high-mass accretor. Flux ratios for several helium lines were extracted from the Doppler tomograms for the disc and bright spot region, and compared with single-slab Local Thermodynamic Equilibrium (LTE) models with variable electron densities and path lengths to estimate the disc and bright spot temperature. Good agreement between data and the model in three out of four systems was found for the disc region. All three systems show similar disc temperatures of ˜10 500 K. In contrast, only weak agreement between observation and models was found for the bright spot region.

Kupfer, T.; Groot, P. J.; Levitan, D.; Steeghs, D.; Marsh, T. R.; Rutten, R. G. M.; Nelemans, G.

2013-07-01

249

Regulating Critical Period Plasticity: Insight from the Visual System to Fear Circuitry for Therapeutic Interventions  

Directory of Open Access Journals (Sweden)

Full Text Available Early temporary windows of heightened brain plasticity called critical periods developmentally sculpt neural circuits and contribute to adult behavior. Regulatory mechanisms of visual cortex development –the preeminent model of experience-dependent critical period plasticity- actively limit adult plasticity and have proved fruitful therapeutic targets to reopen plasticity and rewire faulty visual system connections later in life. Interestingly, these molecular mechanisms have been implicated in the regulation of plasticity in other functions beyond vision. Applying mechanistic understandings of critical period plasticity in the visual cortex to fear circuitry may provide a conceptual framework for developing novel therapeutic tools to mitigate aberrant fear responses in post traumatic stress disorder. In this review, we turn to the model of experience-dependent visual plasticity to provide novel insights for the mechanisms regulating plasticity in the fear system. Fear circuitry, particularly fear memory erasure, also undergoes age-related changes in experience-dependent plasticity. We consider the contributions of molecular brakes that halt visual critical period plasticity to circuitry underlying fear memory erasure. A major molecular brake in the visual cortex, perineuronal net formation, recently has been identified in the development of fear systems that are resilient to fear memory erasure. The roles of other molecular brakes, myelin-related Nogo receptor signaling and Lynx family proteins– endogenous inhibitors for nicotinic acetylcholine receptor, are explored in the context of fear memory plasticity. Such fear plasticity regulators, including epigenetic effects, provide promising targets for therapeutic interventions.

HirofumiMorishita

2013-11-01

250

Extended Horizon Liftings for Periodic Gain Adjustments in Control Systems, and for Equalization of Communication Channels  

Science.gov (United States)

Periodic gain adjustment in plants of irreducible order, n, or for equalization of communications channels is effected in such a way that the plant (system) appears to be minimum phase by choosing a horizon time N greater then n of liftings in periodic input and output windows Pu and Py, respectively, where N is an integer chosen to define the extent (length) of each of the windows Pu and Py, and n is the order of an irreducible input/output plant. The plant may be an electrical, mechanical or chemical system, in which case output tracking (OT) is carried out for feedback control or a communication channel, in which case input tracking (IT) is carried out. Conditions for OT are distinct from IT in terms of zero annihilation, namely for OT and of IT, where the OT conditions are intended for gain adjustments in the control system, and IT conditions are intended for equalization for communication channels.

Bayard, David S. (Inventor)

1996-01-01

251

POMULT: A program for computing periodic orbits in Hamiltonian systems based on multiple shooting algorithms  

Science.gov (United States)

POMULT is a FORTRAN code for locating Periodic Orbits and Equilibrium Points in Hamiltonian systems based on 2-point boundary value solvers which use multiple shooting algorithms. The code has mainly been developed for locating periodic orbits in molecular Hamiltonian systems with many degrees of freedom and it utilizes a damped Newton—Raphson method and a secant method. The Graphical User Interface has also been written in the tcl-tk script language for interactively manipulating the input and output data. POMULT provides routines for a general analysis of a dynamical system such as fast Fourier transform of the trajectories, Poincaré surfaces of sections, maximum Lyapunov exponents and evaluation of the classical autocorrelation functions and power spectra.

Farantos, Stavros C.

1998-02-01

252

Cataclysmic Variables below the Period Gap: Mass Determinations of 14 Eclipsing Systems  

CERN Document Server

We present high-speed, three-colour photometry of the eclipsing cataclysmic variables CTCV 1300, CTCV 2354 and SDSS 1152. All three systems are below the observed "period gap" for cataclysmic variables. For each system we determine the system parameters by fitting a parameterised model to the observed eclipse light curve by chi-squared minimisation. We also present an updated analysis of all other eclipsing systems previously analysed by our group. New donor masses are generally between 1 and 2 sigma of those originally published, with the exception of SDSS 1502 and DV UMa. We note that the donor mass of SDSS 1501 has been revised upwards by 0.024Msun. This system was previously identified as having evolved passed the minimum orbital period for cataclysmic variables, but the new mass determination suggests otherwise. Our new analysis confirms that SDSS 1035 and SDSS 1433 have evolved past the period minimum for cataclysmic variables, corroborating our earlier studies. We find that the radii of donor stars are...

Savoury, C D J; Dhillon, V S; Marsh, T R; Gaensicke, B T; Copperwheat, C M; Kerry, P; Hickman, R D G; Parsons, S G

2011-01-01

253

Period ratios in multi-planetary systems discovered by Kepler are consistent with planet migration  

CERN Document Server

The Kepler planet candidates are an interesting testbed for planet formation scenarios. We present results from N-body simulations of multi-planetary systems that resemble those observed by Kepler. We add both smooth (Type I/II) and stochastic migration forces. The observed period ratio distribution is inconsistent with either of those two scenarios on its own. However, applying both stochastic and smooth migration forces to the planets simultaneously results in a period ratio distribution that is similar to the observed one. This is a natural scenario if planets form in a turbulent proto-planetary disk where these forces are always present. We show how the observed period ratio and eccentricity distribution can constrain the relative strength of these forces, a parameter which has been notoriously hard to predict for decades. We make the source code of our simulations and the initial conditions freely available to enable the community to expand this study and include effect other than planetary migration.

Rein, Hanno

2012-01-01

254

Analysis and enhancement of torsional vibration stopbands in a periodic shaft system  

International Nuclear Information System (INIS)

The band structure and the enhancement of stopbands in a periodic shaft are investigated. The band structures created by a hard ring and a locally resonant (LR) ring are studied first. A uniform method for analysing the band structures of periodic shafts with various attached structures is proposed. Furthermore, the enhancement of the stopbands is discussed. The properties of a shaft with a hard ring and an LR ring in different positions are studied, and a wide, combined gap is created at low frequencies. Additionally, continuous beams are also introduced to enhance the stopbands. Some helpful methods for analysis, prediction and increasing the width of stopbands in a periodic shaft system are provided. (paper)

2013-04-10

255

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 $$ dot{u}_i(t=u_i(tBig[r_i(t-a_{ii}(tu_i(t -sum_{j=1, jeq i}^na_{ij}(tu_jig(t-au_j(t,u_1(t, dots,u_n(tigBig], $$ where $r_i,a_{ii}>0$, $a_{ij}geq0(jeq i$, $i,j=1,2,dots,n$ are almost periodic functions, $au_iin C(mathbb{R}^{n+1},mathbb{R}$, and $au_i(i=1,2,dots,n$ are almost periodic in $t$ uniformly for $(u_1,dots,u_n^Tinmathbb{R}^n$. An example and its simulation figure illustrate our results.

Yongkun Li

2012-06-01

256

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

257

Effect of dielectric responses on localization in 1D random periodic-on-average systems  

CERN Document Server

Dielectric response effects on wave localization in random periodic-on-average layered systems (POAS) are studied. Based on Monte Carlo simulations and products of Random Matrices, statistics of the Lyapunov exponent are determined efficiently for very long systems. A novel oscillatory behavior for localization is found and explained for mildly strong scattering conditions. We also show the emergence of strongly localized states in metallic layered systems with intermediate disorder for frequencies above the plasma frequency $\\omega_{p}$ of metals, as is not shown in dielectrics. Furthermore, the violation of universal single parameter scaling behaviors in different regimes of multiple scattering is discussed.

Wang Chao Cheng; Wang, Cheng-Ching; Luan, Pi-Gang

2002-01-01

258

Single thrust period missions to Uranus for unmanned nuclear-electric propulsion systems  

Science.gov (United States)

The effects of trip time, propulsion time, and specific powerplant mass are studied for optimized unmanned probe spacecraft on missions to Uranus with nuclear-electric propulsion systems. Electric propulsion is confined to a single thrust period at the beginning of each mission. Mission profiles include both high-thrust and electric-propulsion Earth-departure modes for planet flyby and orbital capture. Effects of propulsion time and propulsion system parameters are evaluated, and typical design features of the nuclear-electric spacecraft are outlined. Payload capability comparisons are made with systems employing ballistic transfer and solar-electric propulsion.

Zola, C. L.

1973-01-01

259

Using the isotropic periodic sum method to calculate long-range interactions of heterogeneous systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Isotropic periodic sum (IPS) is a method for the calculation of long-range interactions in molecular simulation based on the homogeneity of simulation systems. Three IPS models, 3D IPS, 2D IPS, and 1D IPS have been developed for three common types of homogeneous systems. Based on the fact that 3D IPS can well describe the long-range interactions of a heterogeneous system if a local region larger than the homogeneity scale is used, this work presents a method based on 3D IPS to calculate long-...

Wu, Xiongwu; Brooks, Bernard R.

2008-01-01

260

Chaotic ranges of a unified chaotic system and its chaos for five periodic switch cases  

International Nuclear Information System (INIS)

In this paper, a unified chaotic system is studied in detail. Non-chaotic ranges within ? element of [0, 1] are found, where ? is the constant parameter of the system. Chaotic range longer than ? element of [0, 1], ? element of [-0.015, 1.152], is discovered, which is the extended chaotic range of unified chaotic system. Next, its chaos behaviors for five continuous periodic switch cases, k sin2 ?T, m sin ?t, 0 ? 1 triangular wave, -1 ? 1 triangular wave, and 0 ? 1 sawtooth wave, are presented

2007-07-01

 
 
 
 
261

SEARCHES FOR PERIODIC NEUTRINO EMISSION FROM BINARY SYSTEMS WITH 22 AND 40 STRINGS OF ICECUBE  

Energy Technology Data Exchange (ETDEWEB)

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 {approx}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{sigma} significance after accounting for trials. Neutrino flux upper limits for both periodic and time-integrated emission are provided.

Abbasi, R.; Aguilar, J. A.; Andeen, K.; Baker, M. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Abdou, Y. [Department of Physics and Astronomy, University of Gent, B-9000 Gent (Belgium); Abu-Zayyad, T. [Department of Physics, University of Wisconsin, River Falls, WI 54022 (United States); Ackermann, M.; Bazo Alba, J. L. [DESY, D-15735 Zeuthen (Germany); Adams, J. [Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Ahlers, M. [Department of Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Allen, M. M. [Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Altmann, D. [III. Physikalisches Institut, RWTH Aachen University, D-52056 Aachen (Germany); Auffenberg, J. [Department of Physics, University of Wuppertal, D-42119 Wuppertal (Germany); Bai, X. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Barwick, S. W. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Bay, R. [Department of Physics, University of California, Berkeley, CA 94720 (United States); Beattie, K. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Beatty, J. J. [Department of Physics and Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States); Bechet, S. [Universite Libre de Bruxelles, Science Faculty CP230, B-1050 Brussels (Belgium); Becker, J. K. [Fakultaet fuer Physik and Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Collaboration: IceCube Collaboration; and others

2012-04-01

262

A LACK OF SHORT-PERIOD MULTIPLANET SYSTEMS WITH CLOSE-PROXIMITY PAIRS AND THE CURIOUS CASE OF KEPLER-42  

International Nuclear Information System (INIS)

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 statistical analysis 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?P2/P1?>2.3 (P1/day)-2/3. This absence 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 three days over the number of multiple candidate systems with similar periods—perhaps a small-planet counterpart to the hot Jupiters

2013-09-01

263

On the Eccentricity Distribution of Short-Period Single-Planet Systems  

CERN Document Server

We apply standard Markov chain Monte Carlo (MCMC) analysis techniques for 50 short- period, single-planet systems discovered with radial velocity technique. We develop a new method for accessing the significance of a non-zero orbital eccentricity, namely {\\Gamma} analysis, which combines frequentist bootstrap approach with Bayesian analysis of each simulated data set. We find the eccentricity estimations from {\\Gamma} analysis are generally consistent with results from both standard MCMC analysis and previous references. The {\\Gamma} method is particular useful for assessing the significance of small eccentricities. Our results suggest that the current sample size is insufficient to draw robust conclusions about the roles of tidal interaction and perturbations in shaping the eccentricity distribution of short-period single-planet systems. We use a Bayesian population analysis to show that a mixture of analytical distributions is a good approximation of the underlying eccentricity distribution. For short-perio...

Wang, Ji

2011-01-01

264

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

265

Fractal and chaotic patterns of Nizhnik-Novikov-Veselov system derived from a periodic wave solution  

Energy Technology Data Exchange (ETDEWEB)

Starting from an extended mapping method and a linear variable separation method, new families of variable separation solutions (including solitary wave solutions, periodic wave solutions and rational function solutions) with arbitrary functions for (2+1)-dimensional Nizhnik-Novikov-Veselov system (NNV) are derived. Usually, in terms of solitary wave solutions and rational function solutions, one can find some important localized excitations. However, based on the derived periodic wave solution in this Letter, we find that some novel and interesting localized coherent excitations such as stochastic fractal patterns, regular fractal patterns, chaotic line soliton patterns and chaotic patterns also exist in the NNV system as considering appropriate boundary conditions and/or initial qualifications.

Zhu Haiping [College of Mathematics and Physics, Lishui University, Lishui, Zhejiang 323000 (China)]. E-mail: zhp63521@163.com; Zheng Chunlong [College of Mathematics and Physics, Lishui University, Lishui, Zhejiang 323000 (China); Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072 (China); Fang Jianping [College of Mathematics and Physics, Lishui University, Lishui, Zhejiang 323000 (China)

2006-06-19

266

Fractal and chaotic patterns of Nizhnik-Novikov-Veselov system derived from a periodic wave solution  

International Nuclear Information System (INIS)

Starting from an extended mapping method and a linear variable separation method, new families of variable separation solutions (including solitary wave solutions, periodic wave solutions and rational function solutions) with arbitrary functions for (2+1)-dimensional Nizhnik-Novikov-Veselov system (NNV) are derived. Usually, in terms of solitary wave solutions and rational function solutions, one can find some important localized excitations. However, based on the derived periodic wave solution in this Letter, we find that some novel and interesting localized coherent excitations such as stochastic fractal patterns, regular fractal patterns, chaotic line soliton patterns and chaotic patterns also exist in the NNV system as considering appropriate boundary conditions and/or initial qualifications

2006-06-19

267

Fractal and chaotic patterns of Nizhnik Novikov Veselov system derived from a periodic wave solution  

Science.gov (United States)

Starting from an extended mapping method and a linear variable separation method, new families of variable separation solutions (including solitary wave solutions, periodic wave solutions and rational function solutions) with arbitrary functions for (2+1)-dimensional Nizhnik Novikov Veselov system (NNV) are derived. Usually, in terms of solitary wave solutions and rational function solutions, one can find some important localized excitations. However, based on the derived periodic wave solution in this Letter, we find that some novel and interesting localized coherent excitations such as stochastic fractal patterns, regular fractal patterns, chaotic line soliton patterns and chaotic patterns also exist in the NNV system as considering appropriate boundary conditions and/or initial qualifications.

Zhu, Hai-Ping; Zheng, Chun-Long; Fang, Jian-Ping

2006-06-01

268

Rough solutions for the periodic Schr\\"odinger - Kortweg-deVries system  

CERN Document Server

We prove two new mixed sharp bilinear estimates of Schr\\"odinger-Airy type. In particular, we obtain the local well-posedness of the Cauchy problem of the Schr\\"odinger - Kortweg-deVries (NLS-KdV) system in the \\emph{periodic setting}. Our lowest regularity is $H^{1/4}\\times L^2$, which is somewhat far from the naturally expected endpoint $L^2\\times H^{-1/2}$. This is a novel phenomena related to the periodicity condition. Indeed, in the continuous case, Corcho and Linares proved local well-posedness for the natural endpoint $L^2\\times H^{-{3/4}+}$. Nevertheless, we conclude the global well-posedness of the NLS-KdV system in the energy space $H^1\\times H^1$ using our local well-posedness result and three conservation laws discovered by M. Tsutsumi.

Arbieto, A; Mathéus, C; Arbieto, Alexander; Corcho, Adan; Matheus, Carlos

2005-01-01

269

Stability of Closed Loop Controlled Repetitive Periodic System applied to control of CD-Player  

DEFF Research Database (Denmark)

In this paper a criterion for stability of specific control scheme for handling linear dynamic control systems with repetitive periodic sensor faults is derived. The given system and control scheme are described and defined. By combining these with the lifting technique a necessary and sufficient stability criterion is derived. This criterion is following applied to an example on a feature based control scheme for handling CD-players playing CDs with surface faults. This feature based control scheme is handling repetitive periodic sensor faults. The feature based control scheme approximates the repetitive sensor faults (surface faults). The fault approximations are subsequently subtracted from the measurements, and the influence from these repetitive sensor faults are thereby removed from the computed control signals.

Odgaard, Peter Fogh; Stoustrup, Jakob

2005-01-01

270

A case for shutdown cooling system exemption from the periodic inspection program  

International Nuclear Information System (INIS)

The Periodic Inspection Program (PIP) is conducted at CANDU stations to comply with the mandatory requirements in Canadian Standards Association (CSA) Standards N285.4, N285.5 and N287.7. A heavily-inspected system in this program is the Shutdown Cooling (SDC) System, which accounts for about 15% of the overall inspections. This paper presents a case to remove most of the SDC System from the PIP since the worst-case accident of the SDC System results in public radiological doses that are low enough to allow exemption under N285.4. This provides an opportunity for CANDU owners to inspect the SDC System on an owner-prescribed basis at their own schedule. This will reduce costs and personnel doses and allow the allocation of resources and funding to more safety-important inspections. (author)

2007-06-03

271

A case for shutdown cooling system exemption from the periodic inspection program  

Energy Technology Data Exchange (ETDEWEB)

The Periodic Inspection Program (PIP) is conducted at CANDU stations to comply with the mandatory requirements in Canadian Standards Association (CSA) Standards N285.4, N285.5 and N287.7. A heavily-inspected system in this program is the Shutdown Cooling (SDC) System, which accounts for about 15% of the overall inspections. This paper presents a case to remove most of the SDC System from the PIP since the worst-case accident of the SDC System results in public radiological doses that are low enough to allow exemption under N285.4. This provides an opportunity for CANDU owners to inspect the SDC System on an owner-prescribed basis at their own schedule. This will reduce costs and personnel doses and allow the allocation of resources and funding to more safety-important inspections. (author)

Handbury, J. [Canadian Power Utility Services Ltd., Toronto, Ontario (Canada)

2007-07-01

272

A high-density ternary barcode detection system employing a stable fixed-period delay method  

Science.gov (United States)

A fixed-period delay method is proposed to increase the detection range and detection stability of a ternary barcode detection system. The system combines an envelope differential detection technique containing nonlinear filtering and a fixed-period delay to detect the barcode over a longer range and at higher scanning speeds while being simple and capable of handling a large amount of information. The system was demonstrated with its miniaturized circuit, and it was established that the detection range of the system for a minimum bar width W = 0.25 mm was 1.8 times that of the conventional count-latch envelope differential technique because of the stable delay achieved by a shift register and the noise suppression by a nonlinear filter. In addition, the system operated at a maximum scanning speed of 8.3 times that of conventional charge-coupled device cameras under the practical detection range for W = 0.3 mm. This system is expected to facilitate the real-time identification of goods on production lines and in automated warehouses.

Wakaumi, Hiroo

2011-09-01

273

Swift computation of the periodic steady state solution of power systems containing TCSCs  

Energy Technology Data Exchange (ETDEWEB)

In this contribution a state space model of the TCSC is described. The periodic steady state solution of the entire power system is efficiently obtained in the time domain with the application of a Newton method based on a numerical differentiation procedure. The solution is compared in terms of accuracy and efficiency against the solution obtained with a conventional brute force method based on the fourth order Runge-Kutta numerical integration method. (author)

Medina, A.; Ramos-Paz, A.; Fuerte-Esquivel, C.R. [Ciudad Universitaria Morelia (Mexico). Facultad de Ingenieria Electrica

2003-11-01

274

A low-dimensional model system for quasi-periodic plasma perturbations  

International Nuclear Information System (INIS)

Larger scale plasma instabilities not leading to an immediate termination of a discharge often result in periodic nonlinear perturbations of the plasma. A minimal possible model is formulated for description of the system with drive and relaxation processes which have different time scales. The model is based on two equations: the first being responsible for the relaxation dynamics and the second for the drive. The model can be generalized to describe the pellet injection.

2011-06-01

275

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 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 confi...

Thorndahl, Søren

2008-01-01

276

Vector Potential Approach for Response of Infinite Periodic Systems to Electric Fields  

Science.gov (United States)

A detailed study of the vector potential approach (VPA) for the response of periodic systems to a finite electric field is carried out using a parameterized model self-consistent field (SCF) polymer Hamiltonian. Specific issues discussed include ``smoothing'' of crystal orbitals, convergence and accuracy of SCF solutions as a function of field and number of k points, Zener tunneling, field-dependent band structure, determination of (non)linear susceptibilities, and nuclear relaxation.

Kirtman, Bernard; Springborg, Michael

2007-12-01

277

Markovian Controllable Queueing Systems with Hysteretic Policies: Busy Period and Waiting Time Analysis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study Markovian queueing systems in which the service rate varies whenever the queue length changes. More specifically we consider controllable queues operating under the so-called hysteretic policy which provides a rather versatile class of operating rules for increasing and decreasing service rate at the arrival and service completion times. The objective of this paper is to investigate algorithmically the busy period and the waiting time distributions. Our analysis supplements the class...

Artalejo, Jesu?s R.; Economou, Antonis

2005-01-01

278

The HD 192263 system: planetary orbital period and stellar variability disentangled  

CERN Document Server

As part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS), 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 \\pm 0.0022 days. We use 10 years of Automated Photoelectric Telescope (APT) 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 a...

Dragomir, Diana; Henry, Gregory W; Ciardi, David R; Fischer, Debra A; Howard, Andrew W; Jensen, Eric L N; Laughlin, Gregory; Mahadevan, Suvrath; Matthews, Jaymie M; Pilyavsky, Genady; von Braun, Kaspar; Wang, Sharon X; Wright, Jason T

2012-01-01

279

Monitoring and evaluation of radon mitigation systems over a two-year period  

Energy Technology Data Exchange (ETDEWEB)

Fourteen single-family detached houses in the Spokane, Washington, and Coeur D'Alene, Idaho, area were tracked for two years following mitigation for elevated indoor concentrations of radon. Each house was monitored quarterly using mailed alpha-track radon detectors deployed in each zone of the structure. During the second heating season following mitigation, radon concentrations were monitored continuously for several weeks in seven of the houses, each house and mitigation system was inspected and selected measurements were performed in order to access mitigation system performance. Occupants were also interviewed regarding their maintenance, operation, and subjective evaluation of the radon mitigation system(s). The quarterly alpha-track measurements showed an increase in radon levels in a majority of the homes during many of the follow-up measurement periods compared to concentrations measured immediately after mitigation. The greatest increases in radon concentrations occurred in 3 of the 4 houses equipped with basement pressurization systems where radon levels approached the pre-mitigation levels during at least one of the follow-up measurement periods. In some of the houses mitigated with subsurface ventilation, radon concentrations generally increased over the course of the follow-up periods. Factors causing decreased mitigation system performance included: (1) build up of debris on the soil at the outlet of subsurface pressurization pipes; (2) noisy and vibrating fans were turned off; (3) air-to-air heat exchanger, basement pressurization, and subsurface ventilation fans were turned off and fan speeds reduced; and (4) crawl space vents were closed or sealed. 7 refs., 2 figs., 2 tabs.

Prill, R.J.; Fisk, W.J.; Turk, B.H.

1988-09-01

280

Three-Dimensional Design of a Non-Axisymmetric Periodic Permanent Magnet Focusing System  

CERN Document Server

A three-dimensional (3D) design is presented of a non-axisymmetric periodic permanent magnet focusing system which will be used to focus a large-aspect-ratio, ellipse-shaped, space-charge-dominated electron beam. In this design, an analytic theory is used to specify the magnetic profile for beam transport. The OPERA3D code is used to compute and optimize a realizable magnet system. Results of the magnetic design are verified by two-dimensional particle-in-cell and three-dimensional trajectory simulations of beam propagation using PFB2D and OMNITRAK, respectively. Results of fabrication tolerance studies are discussed.

Chen Chi Ping; Radovinsky, Alexey; Zhou, Jing

2005-01-01

 
 
 
 
281

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

CERN Multimedia

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

282

Period changes in a close binary system with mass and angular momentum loss  

International Nuclear Information System (INIS)

The parameters of a close binary system with mass exchange between components and the primary filling its Roche lobe are estimated in the restricted three-body approximation. Gasodynamics of the mass transfer and processes in star interiors depending on it are not considered. It is assumed that the angular momentum of the exchaned matter entering the Roche lobe of the secondary is carried away from the system. The computed mass and momentum losses, the distance between component centers and the orbital period are different from the results obtained previously using another model of the mass transfer. (author)

1979-01-01

283

Shaping the spatial periodic electron beams in the system of magnetron guns with secondary emission cathodes  

CERN Document Server

The study on the electron beam generation processes in the system of the magnetron guns with the secondary-emission cathodes and anodes in form of periodically positioned metallic pins is carried out. It is shown, that the beam summary current of approximately 22 A is obtained in the system, consisting of four cells, which corresponds to the quadruplicate beam current value of the one cell. The pulse capacity thereby constituted approximately 600 kW. Such beams may be applied in the multipulse microwave devices

Ajzatskij, N I; Zakutin, V V; Reshetnyak, N G; Romasko, V P; Volkolupov, Yu Ya; Krasnogolovets, M A

2001-01-01

284

Optimal selection of pit haulage system in transition period for mining-in-areas  

Energy Technology Data Exchange (ETDEWEB)

Taking ATB surface mine, Pingshuo Coal Company as an example, the feature of pit haulage system was analysed in the transition period for mining-in-areas at flat-bedded or gently-inclined deposit. Methods for optimizing pit haulage system were proposed. According to dumping sites and their volumes, the best haulage paths for overburden from different bench areas were optimized. Other measures were suggested such as faster advancing the upper benches in the old mining areas. 5 refs., 3 figs., 2 tabs.

Shang, T.; Cai, Q.; Liu, X.; Xu, Z. [CUMT, Xuzhou (China). School of Mineral and Safety Engineering

2004-07-01

285

The Education System in East Jerusalem during the Period of Jordanian Rule, 1948-1967  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The article below deals with the Arab educational system in East Jerusalem during the period of Jordanian rule, 1948-1967. Its main aim is to examine the attempts and efforts of the Jordanian government promote a new sense of identity among the Palestinians residing in Jerusalem in order to strengthen their loyalty to the Hashemite regime that had annexed the West Bank and turned it into an inseparable part of the Kingdom of Jordan. The article shows how the educational system was inducted...

Mustafa Abbasi

2013-01-01

286

Models for maintenance optimization: a study for repairable systems and finite time periods  

Energy Technology Data Exchange (ETDEWEB)

The problem of selecting a suitable maintenance policy for repairable systems and for a finite time period is presented. Since the late seventies, examples of models assessing corrective and preventive maintenance policies over an equipment life cycle exist in the literature. However, there are not too many contributions regarding real implementation of these models in the industry, considering realistic timeframes and for repairable systems. Modeling this problem requires normally the representation of different corrective and/or preventive actions that could take place at different moments, driving the equipment to different states with different hazard rates. An approach to pattern the system under finite periods of time has been the utilization of semi-Markovian probabilistic models, allowing later a maintenance policy optimization using dynamic programming. These models are very flexible to represent a given system, but they are also complex and therefore very difficult to handle when the number of the system possible states increases. This paper explores the trade-off between flexibility and complexity of these models, and presents a comparison in terms of model data requirements versus potential benefits obtained with the model.

Crespo Marquez, Adolfo; Sanchez Heguedas, Antonio

2002-03-01

287

Phased mission modelling of systems with maintenance-free operating periods using simulated Petri nets  

International Nuclear Information System (INIS)

A common scenario in engineering is that of a system which operates throughout several sequential and distinct periods of time, during which the modes and consequences of failure differ from one another. This type of operation is known as a phased mission, and for the mission to be a success the system must successfully operate throughout all of the phases. Examples include a rocket launch and an aeroplane flight. Component or sub-system failures may occur at any time during the mission, yet not affect the system performance until the phase in which their condition is critical. This may mean that the transition from one phase to the next is a critical event that leads to phase and mission failure, with the root cause being a component failure in a previous phase. A series of phased missions with no maintenance may be considered as a maintenance-free operating period (MFOP). This paper describes the use of a Petri net (PN) to model the reliability of the MFOP and phased missions scenario. The model uses Monte-Carlo simulation to obtain its results, and due to the modelling power of PNs, can consider complexities such as component failure rate interdependencies and mission abandonment. The model operates three different types of PN which interact to provide the overall system reliability modelling. The model is demonstrated and validated by considering two simple examples that can be solved analytically

2008-07-01

288

Phased mission modelling of systems with maintenance-free operating periods using simulated Petri nets  

Energy Technology Data Exchange (ETDEWEB)

A common scenario in engineering is that of a system which operates throughout several sequential and distinct periods of time, during which the modes and consequences of failure differ from one another. This type of operation is known as a phased mission, and for the mission to be a success the system must successfully operate throughout all of the phases. Examples include a rocket launch and an aeroplane flight. Component or sub-system failures may occur at any time during the mission, yet not affect the system performance until the phase in which their condition is critical. This may mean that the transition from one phase to the next is a critical event that leads to phase and mission failure, with the root cause being a component failure in a previous phase. A series of phased missions with no maintenance may be considered as a maintenance-free operating period (MFOP). This paper describes the use of a Petri net (PN) to model the reliability of the MFOP and phased missions scenario. The model uses Monte-Carlo simulation to obtain its results, and due to the modelling power of PNs, can consider complexities such as component failure rate interdependencies and mission abandonment. The model operates three different types of PN which interact to provide the overall system reliability modelling. The model is demonstrated and validated by considering two simple examples that can be solved analytically.

Chew, S.P.; Dunnett, S.J. [Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough, Leics (United Kingdom); Andrews, J.D. [Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough, Leics (United Kingdom)], E-mail: j.d.andrews@lboro.ac.uk

2008-07-15

289

Theory of finite periodic systems - I: General expressions and various simple and illustrative examples  

International Nuclear Information System (INIS)

A comprehensive presentation of a new approach to finite periodic systems is given. The novel and general expressions obtained here, allow simple and precise calculations of various physical quantities characteristic of crystalline systems. Transmission amplitudes through n-cell multichannel quantum systems are rigorously derived. General expressions for several physical quantities are entirely expressed in terms of single-cell amplitudes and a new class of polynomials pN,n. Besides the general expressions, we study some superlattice properties as the band structure and its relation with the phase coherence phenomena, the level density and the Kronig-Penney model as its continuous espectrum limit. Bandstructure tailoring, optical multilayer systems, resonant energies and functions and channel-mixing effects in multichannel transport process are also analysed in the light of the new approach. (author)

2001-01-01

290

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

International Nuclear Information System (INIS)

An overview is given of the number of active thermal solar energy systems that have been installed in the Netherlands during the period 1975-1992. By the end of 1992, 8,300 systems have been installed, of which 6,000 were domestic solar hot water systems. The uncertainty in these figures is 10%. Several sources were used to determine the number of systems installed. The two main sources were the files of the solar industry association 'Holland Solar' (data until 1988), and the Dutch subsidy administrator 'Senter' for data from 1988 up to and including 1992. At the end of 1992 preparations were made for the installation of approximately 3,000 domestic solar water heaters in 1993. It is recommended to carry out an inventory every three months and to compile data on investment costs. 17 figs., 7 appendices

1993-01-01

291

Harmless delays in a discrete ratio-dependent periodic predator-prey system  

Directory of Open Access Journals (Sweden)

Full Text Available Verifiable criteria are established for the existence of positive periodic solutions and permanence of a delayed discrete periodic predator-prey model with Holling-type II functional response N1(k+1=N1(kexp⁡{b1(k−a1(kN1(k−[τ1]−α1(kN2(k/(N1(k+m(kN2(k} and N2(k+1=N2(kexp⁡{−b2(k+α2(kN1(k−[τ2]/(N1(k−[τ2]+m(kN2(k−[τ2]}. Our results show that the delays in the system are harmless for the existence of positive periodic solutions and permanence of the system. In particular our investigation confirms that if the death rate of the predator is rather small as well as the intrinsic growth rate of the prey is relatively large, then the species could coexist in the long run.

Wan-Tong Li

2006-06-01

292

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

2012-06-01

293

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

294

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

2004-10-01

295

Breathers on a Background Periodic and Quasiperiodic Solutions of Extended Discrete Nonlinear Wave Systems  

CERN Document Server

In this paper we investigate the emergence of time-periodic and and time-quasiperiodic (sometimes infinitely long lived and sometimes very long lived or metastable) solutions of discrete nonlinear wave equations: discrete sine Gordon, discrete $\\phi^4$ and discrete nonlinear Schr\\"odinger. The solutions we consider are periodic oscillations on a kink or standing wave breather background. The origin of these oscillations is the presence of internal modes, associated with the static ground state. Some of these modes are associated with the breaking of translational invariance, in going from a spatially continuous to a spatially discrete system. Others are associated with discrete modes which bifurcate from the continuous spectrum. It is also possible that such modes exist in the continuum limit and persist in the discrete case. The regimes of existence, stability and metastability of states as the lattice spacing is varied are investigated analytically and numerically. A consequence of our analysis is a class o...

Kevrekidis, P G

2002-01-01

296

Mixed-space formalism for the dielectric response in periodic systems  

International Nuclear Information System (INIS)

We present a useful formalism for the calculation of the polarizability and dielectric response of periodic systems. Our approach is to introduce intermediate ''mixed-space'' functions with the full translational periodicity of the lattice. This is a considerable advantage over existing real-space methods since the decay length of a response function [such as ?(r,r'|?)] can be significantly larger than the Wigner-Seitz cell radius. Further, we show that, in supercell calculations, these mixed-space functions decay as fast as the corresponding real-space quantities within one supercell, so that the present scheme can be combined with usual real-space cutoff techniques. The advantage of the present method compared to a standard reciprocal space approach is exemplified for the case of bulk silicon and for the case of a Si surface in a slab geometry

1995-07-15

297

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

CERN Multimedia

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

298

Large-scale periodicity in the distribution of QSO absorption-line systems  

CERN Multimedia

The spatial-temporal distribution of absorption-line systems (ALSs) observed in QSO spectra within the cosmological redshift interval z = 0.0--4.3 is investigated on the base of our updated catalog of absorption systems. We consider so called metallic systems including basically lines of heavy elements. The sample of the data displays regular variations (with amplitudes ~ 15 -- 20%) in the z-distribution of ALSs as well as in the eta-distribution, where eta is a dimensionless line-of-sight comoving distance, relatively to smoother dependences. The eta-distribution reveals the periodicity with period Delta eta = 0.036 +/- 0.002, which corresponds to a spatial characteristic scale (108 +/- 6) h(-1) Mpc or (alternatively) a temporal interval (350 +/- 20) h(-1) Myr for the LambdaCDM cosmological model. We discuss a possibility of a spatial interpretation of the results treating the pattern obtained as a trace of an order imprinted on the galaxy clustering in the early Universe.

Ryabinkov, A I; 10.1007/s10509-010-0448-1

2010-01-01

299

Study of universality and critical behavior in periodically driven interacting cold atomic system  

Science.gov (United States)

Strongly driven nonlinear oscillators show a variety of interesting phenomena such as period doubling, bifurcation, chaos. Since their resonant behaviors are very sensitive to external perturbation, they have now been widely adopted for the precise determination of physical quantities. The key concept to these researches is the development of bistable or period-2 states, which are, in most cases, energetically degenerate. If particles interact each other, however, this degeneracy of two attractors can be lifted up. For example, in the simple case of all-to-all attractive interaction, particles will be preferably directed into more populated attractors. Being incorporated with random fluctuation which tries to equilibrate population in each attractor, this lifting-up becomes dependent on the system size, or the total number of particles, as recently observed as spontaneous symmetry breaking in cold atomic system which inherently possesses the light-induced attractive interaction. In particular, this dependence seems to show a sort of critical behavior. Here we have elucidated the criticality existing in the strongly driven interacting many-particle system consisted up of cold atoms from static and dynamic perspectives.

Heo, Myoung-Sun; Kim, Yonghee; Jhe, Wonho; Noh, Heung-Ryoul

2008-03-01

300

Extended horizon lifting for periodic gain adjustment in control systems, and for equalization of communication channels  

Science.gov (United States)

Periodic gain adjustment in plants of irreducible order, n, or for equalization of communications channels is effected in such a way that the plant (system) appears to be minimum phase by choosing a horizon time N is greater than n of liftings in periodic input and output windows rho sub u and rho sub y, respectively, where N is an integer chosen to define the extent (length) of each of the windows rho sub u and rho sub y, and n is the order of an irreducible input/output plant. The plant may be an electrical, mechanical, or chemical system, in which case output tracking (OT) is carried out for feedback control or a communication channel, in which case input tracking (IT) is performed. Conditions for OT are distinct from IT in terms of zero annihilation, namely H(sub s)H(sub s)(sup +) = I for OT and H(sub s)H(sub s)(sup +) = I of IT, where the OT conditions are intended for gain adjustments in the control system, and IT conditions are intended for equalization for communication channels.

Bayard, David S. (inventor)

1994-01-01

 
 
 
 
301

Improvements of the Periodic Safety Review (PSR) System for Operating Nuclear Power Plants  

International Nuclear Information System (INIS)

A PSR (Periodic Safety Review) for operating nuclear power plants is a comprehensive safety review of all important aspects of safety, against current safety standards and practices, carried out at regular intervals of ten years. The PSR has been implemented by European States such as the UK, France, etc., and Japan in earlier times. IAEA has strongly recommended its implementation in accordance with the Convention on Nuclear Safety. Korea became a member of the Convention on Nuclear Safety in September 1995, and formally adopted the PSR system through revision of Atomic Energy Act in January 2001. Recently the PSR results of Kori Unit 1 and Wolsong Unit 1 was approved by the regulatory body. And, safety review of the PSR results for Kori units 3 and 4 is in progress. Korea has successfully carried out the implementation of the PSR system despite little experience. However, some findings were derived through the process of PSR implementations. For resolving these findings, the implementation cases of UK and France which have plenty of experiences in PSR were analyzed and the newly revised IAEA safety standards No. NS-G-2.10, 'Periodic safety review of nuclear power plants' was reviewed. Some improvements of the PSR system were proposed, based on this analysis and review

2005-05-26

302

Stationary vibrations of a system with an impact absorber subjected to periodic impulses of finite duration ???????????? ????????? ??????? ? ??????? ????????? ??? ???????? ????????????? ????????? ???????? ????????????  

Directory of Open Access Journals (Sweden)

Full Text Available Impulsive loadings, or repetitive brief impacts, produced by machines and mechanisms of the shock action, are widely spread in the engineering practice. In many cases, trustworthy results of their dynamic analyses can be obtained by taking account of the shape and duration of their impulses. In the paper, the periodic mode of the system motion and the parameters of the impact absorber applicable to one-sided periodic impulses of rectangular form are examined. The structure to be protected and the absorber are simulated as a system of a single collision of masses. The impacts are accepted to be instantaneous and taken into account by means of the coefficient of restitution. The damping properties of the protected structure and the absorber are considered on the basis of the viscid friction hypothesis; therefore, the damping properties of the whole system are disproportionate. The relations identified in the course of the research are used to find the impulse frequency characteristics (IFC of the protected structure to identify the absorber parameters. The affect of duration of external impulses produced onto the IFC, characterized by the drastic increase in the amplitudes as compared to that in the case of a single impulse of the same magnitude, is the subject of research. It is proven that the maximal ordinates of IFC decrease slightly against the increase in the duration of external impulses; therefore, the efficiency of the impact absorber changes insignificantly, and it is equivalent to that of a dynamic absorber. It is noteworthy that if the duration of external impulses is under 10 % of the duration of the period, they may be replaced by instantaneous impulses.??????????? ?????????????? ????????? ???????????? ???????????? ???????, ????????? ???????????????? ?????????????? ?????????? ? ???????????????? ???????????? ????. ??????? ????????????? ???????, ??????????? ?????????? ???????? ??????? ? ????? ??????????? ???? ?? ?????? ?????????? ??????? ????????? ????????????? ?????, ??????? ???????????? ??? ?????? ??????????? ?????????? ????????.

Dukart Adam Vilebal'dovich

2012-04-01

303

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 standa...

Lindbo, Dag; Tornberg, Anna-karin

2011-01-01

304

Simulated annealing algorithm for finding periodic orbits of multi-electron atomic systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We adapt the simulated annealing algorithm to the search of periodic orbits for classical multi-electron atomic systems. This is done by minimizing the n-th return distance to the initial position on a Poincare surface of section under an energy constraint. Here we give evidence of the feasibility of the method by applying it to the helium atom in the ground state for one to three spatial dimensions. We examine the structure of the dynamics and connect its organization to th...

Mauger, Francois; Chandre, Cristel; Uzer, Turgay

2010-01-01

305

Quantum Spectra and Wave Functions in Terms of Periodic Orbits for Weakly Chaotic Systems  

CERN Document Server

Special quantum states exist which are quasiclassical quantizations of regions of phase space that are weakly chaotic. In a weakly chaotic region, the orbits are quite regular and remain in the region for some time before escaping and manifesting possible chaotic behavior. Such phase space regions are characterized as being close to periodic orbits of an integrable reference system. The states are often rather striking, and can be concentrated in spatial regions. This leads to possible phenomena. We review some methods we have introduced to characterize such regions and find analytic formulas for the special states and their energies.

Prange, R E; Zaitsev, O P; Zaitsev, Oleg

2000-01-01

306

Real space method for the electronic structure of one-dimensional periodic systems  

Energy Technology Data Exchange (ETDEWEB)

We present a real space pseudopotential method for calculating the electronic structure of one-dimensional periodic systems such as nanowires. As an application of this method, we examine H-passivated Si nanowires. The band structure and heat of formation of the Si nanowires are presented and compared to plane wave methods. Our method is able to offer the same accuracy as the traditional plane wave methods but offers a number of computational advantages such as faster convergence for heteropolar nanowires. 2008 American Institute of Physics.

Han, Jiaxin [University of Texas, Austin; Tiago, Murilo L [ORNL; Chan, Tzu-Lian [University of Texas, Austin; Chelikowsky, James [University of Texas, Austin

2008-01-01

307

Existence of periodic travelling waves in Fermi-Pasta-Ulam system on 2D–lattice(in Ukrainian  

Directory of Open Access Journals (Sweden)

Full Text Available It is considered the system of differential equations that describes the dynamics of an infinite system of atoms on 2D{lattice. Results on existence of the periodic travelling waves are obtained.

S. M. Bak

2012-03-01

308

The procedure optimization of maintenance periodicity and planned switching of the important for NPP safety ladder logic systems  

International Nuclear Information System (INIS)

In this work the typical graphs and generalized account algorithms of an optimum control periodicity of the equipment of important for safety systems, are submitted. The criterion of this optimization is maximum probability of the nominated performance functions. Alternative computations of optimization periodicity of circuit system planned switching of the industrial WWER-1000/320 are executed

2000-01-01

309

Quasi-periodic motions in families of dynamical systems order amidst chaos  

CERN Multimedia

This book is on Kolmogorov-Arnol'd-Moser theory for quasi-periodic tori in dynamical systems. It gives an up-to-date report on the role parameters play for persis- tence of such tori, typically occuring on Cantor sets of positive Hausdorff measure inside phase and parameter space. The cases with preservation of symplectic or volume forms or time-reversal symmetries are included. The concepts of Whitney-smoothness and Diophantine approximation of Cantor sets on submanifolds of Euclidean space are treated, as well as Bruno's theory on analytic continuation of tori. Partly this material is new to Western mathematicians. The reader should be familiar with dynamical systems theory, differen- tial equations and some analysis. The book is directed to researchers, but its entrance level is introductory.

Broer, Hendrik W; Sevryuk, Mikhail B

1996-01-01

310

Closed periodic orbits of convective solutions in rapidly rotating system: Double torus knots and links, DTK  

International Nuclear Information System (INIS)

The classification of closed periodic orbits of convection in a rapidly rotating system is given. It is shown that double torus knots and links, DTK, do occur, which is a very wide and important class of knots and links. We also proved that there is no double torus Lorenz knots, this answers question 6 raised by Hill and Murasugi in [Peter Hill, On double-torus knots 1. J Knot Theor Ramif 1999;8(8):1009-48]. It is also shown that the system produces torus knots and links, for some specific parameters. In fact this approach suggests the study of double torus knots and links through dynamical tools, such as symbolic dynamics and templates

2008-04-01

311

Transfer of training on manual control systems differing in short period frequency and damping characteristics  

Science.gov (United States)

Each of four groups of 16 subjects was trained on one of four compensatory tracking tasks that differed with regard to short period natural frequency and damping characteristics. After completion of the training sessions, the members of each group either transferred to a task on which they had not been trained or continued with their original task. Analysis of the training data indicated that relative task difficulty was largely determined by system damping which, however, had little effect on the amount of transfer during the transfer trials. The effect of system frequency was essentially reversed, and a marked interaction between training and transfer frequencies was observed in the transfer data. Similar results were obtained both with relative error scores and transinformation scores. Positive transfer was exhibited by most of the groups when they transferred to tasks on which they had not been trained.

Lincoln, R. S.

1978-01-01

312

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

2013-03-01

313

Dynamical-systems analysis and unstable periodic orbits in reacting flows behind symmetric bluff bodies  

Science.gov (United States)

Dynamical systems analysis is performed for reacting flows stabilized behind four symmetric bluff bodies to determine the effects of shape on the nature of flame stability, acoustic coupling, and vortex shedding. The task requires separation of regular, repeatable aspects of the flow from experimental noise and highly irregular, nonrepeatable small-scale structures caused primarily by viscous-mediated energy cascading. The experimental systems are invariant under a reflection, and symmetric vortex shedding is observed throughout the parameter range. As the equivalence ratio—and, hence, acoustic coupling—is reduced, a symmetry-breaking transition to von Karman vortices is initiated. Combining principal-components analysis with a symmetry-based filtering, we construct bifurcation diagrams for the onset and growth of von Karman vortices. We also compute Lyapunov exponents for each flame holder to help quantify the transitions. Furthermore, we outline changes in the phase-space orbits that accompany the onset of von Karman vortex shedding and compute unstable periodic orbits (UPOs) embedded in the complex flows prior to and following the bifurcation. For each flame holder, we find a single UPO in flows without von Karman vortices and a pair of UPOs in flows with von Karman vortices. These periodic orbits organize the dynamics of the flow and can be used to reduce or control flow irregularities. By subtracting them from the overall flow, we are able to deduce the nature of irregular facets of the flows.

Hua, Jia-Chen; Gunaratne, Gemunu H.; Kostka, Stanislav; Jiang, Naibo; Kiel, Barry V.; Gord, James R.; Roy, Sukesh

2013-09-01

314

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

2011-04-01

315

Evaluation of radon mitigation systems in 14 houses over a two-year period  

International Nuclear Information System (INIS)

Fourteen single-family detached houses in Spokane, Washington, and Coeur D'Alene, Idaho, were monitored for two years after high concentrations of indoor radon had been mitigated. Each house was monitored quarterly using mailed alpha-track radon detectors deployed in each zone of the structure. To assess performance of mitigation systems during the second heating season after mitigation, radon concentrations in seven houses were monitored continuously for several weeks, mitigation systems in all houses were inspected, and selected other measurements were taken. In addition, occupants were also interviewed regarding their maintenance, operation, and subjective evaluation of the radon mitigation systems. Quarterly alpha-track measurements showed that radon levels had increased in most of the homes during many follow-up measurement periods when compared with concentrations measured immediately after mitigation. Mitigation-system performance was adversely affected by (1) accumulated outdoor debris blocking the outlets of subsurface pressurization pipes; (2) fans being turned off (e.g., because of excessive noise or vibration); (3) air-to-air heat exchanger, basement pressurization, and subsurface ventilation fans being turned off and fan speeds reduced; and (4) crawl-space vents being closed or sealed

1990-01-01

316

IP Eri: A surprising long-period binary system hosting a He white dwarf  

CERN Document Server

We determine the orbital elements for the K0 IV + white dwarf (WD) system IP Eri, which appears to have a surprisingly long period of 1071 d and a significant eccentricity of 0.25. Previous spectroscopic analyses of the WD, based on a distance of 101 pc inferred from its Hipparcos parallax, yielded a mass of only 0.43 M$_\\odot$, implying it to be a helium-core WD. The orbital properties of IP Eri are similar to those of the newly discovered long-period subdwarf B star (sdB) binaries, which involve stars with He-burning cores surrounded by extremely thin H envelopes, and are therefore close relatives to He WDs. We performed a spectroscopic analysis of high-resolution spectra from the HERMES/Mercator spectrograph and concluded that the atmospheric parameters of the K0 component are $T_{\\rm eff} = 4960$ K, $\\log{g} = 3.3$, [Fe/H] = 0.09 and $\\xi = 1.5$ km/s. The detailed abundance analysis focuses on C, N, O abundances, carbon isotopic ratio, light (Na, Mg, Al, Si, Ca, Ti) and s-process (Sr, Y, Zr, Ba, La, Ce, N...

Merle, T; Masseron, T; Van Eck, S; Siess, L; Van Winckel, H

2014-01-01

317

Nordic Lightning Information System: Thunderstorm climate of Northern Europe for the period 2002–2011  

Science.gov (United States)

A 10-year statistics (2002–2011) of the Nordic Lightning Information System (NORDLIS) are presented. NORDLIS is a joined lightning location network between Norway, Sweden, Finland, and Estonia, comprising in 2011 of 32 lightning location sensors. Our data set contains a total of 4,121,649 cloud-to-ground (CG) flashes. We show the regional and temporal distribution of lightning in Northern Europe during the study period. Our results indicate that the average annual ground flash density values are greatest in Southern Sweden, Baltic countries and Western Finland. The average number of thunderstorm days is largest in the Baltic countries and Southwestern Sweden, and the annual number of ground flashes has varied during the study period from 250,000 to 620,000. The largest observed daily number of ground flashes is 51,500, and the largest daily ground flash density is about 5 CGs km? 2; this has occurred in southern Sweden in July 2003. The average daily number of ground flashes peaks in mid-July–early-August. Cold season (October–April) thunderstorms occur frequently over the North Sea west of Norway and in the west coast of Denmark. Our results also show that an intense thunderstorm may occur practically anywhere in the Northern Europe except for certain maritime and mountain areas.

Mäkelä, Antti; Enno, Sven-Erik; Haapalainen, Jussi

2014-03-01

318

Chemical effects of (n,2n) reactions on iodate and periodates systems  

International Nuclear Information System (INIS)

The chemical consequences of (n,2n) reactions on cristalline sodium iodate and periodates were investigated measuring the initial yield and the post irradiation thermal annealing yields (90"0C) of the separated fractions I"-, IO_3"- and IO_4"-. NaIO_3, NaIO_3.H_2O and NaIO_4, Na_4H_2IO_6, Na_4I_2O_9.3H_2O containing "1"2"7I and "1"2"9I, or both, were irradiated with 14 MeV neutrons. Results obtained show different effects for each system and that "1"2"6I and "1"2"8I isotopes keep the same behaviour in the irradiated compounds containing only ?"1"2"7I or "1"2"9I and in compounds having both "1"2"7I and "1"2"9I. Neither isotope effect nor qualitative differences on thermal annealing at 90"0C were observed. The annealed fractions in the three studied periodates were IO"-_3 and IO"-_4. These results differ from the ones reported previously for (n,?) reactions on the same compounds

1975-01-01

319

Comparison of the polarizability of periodic systems computed by using the length and velocity operators  

Energy Technology Data Exchange (ETDEWEB)

The theorem relating the length (L) and velocity (V) operators, that permits to compute in two alternative ways the polarizabilities of finite systems, is generalized to periodic infinite cases. The two alternative strategies have been implemented in the CRYSTAL code, that uses Gaussian type basis sets, within the CPHF and CPKS formalisms. The dielectric constant of diamond, SiC, silicon and MgO has been obtained with four different hamiltonians (HF, LDA, PBE, B3LYP). The effect of basis set and other computational parameters are discussed. It turns out that when a relatively extended basis set is used, LDA and PBE results obtained with the L and V operators nearly coincide, whereas HF and B3LYP schemes provide different results, as expected on the basis of the non-commutability of the HF-exchange and length operators.

Rerat, M; Amzallag, E; Baraille, I [Equipe de Chimie Physique, IPREM UMR5254, Universite de Pau, F-64000 Pau (France); Ferrero, M; Dovesi, R [Dipartimento di Chimica IFM, Universita di Torino, Via Giuria 5, I-10125 Torino (Italy)], E-mail: michel.rerat@univ-pau.fr

2008-06-01

320

On the specific heat of heavy-fermion systems using the periodic Anderson model  

Science.gov (United States)

The periodic Anderson model (PAM) represents a paradigm for understanding the physics of heavy-fermion (HF) compounds. In this paper, we study the specific heat of HF systems using the PAM within the framework of dynamical mean-field theory. By examining the systematic variation of specific heat as a function of particle-hole asymmetry and coupling strength, with the natural focus being on strong coupling, it is demonstrated that experimentally measured specific heat of a variety of paramagnetic Kondo insulators such as YbB12, SmB6, FeSi, CeRhSb and HF metals such as CeFeGe3, YbAl3 and CeAl3 can be understood semi-quantitatively using the PAM.

Vidhyadhiraja, N. S.

2007-02-01

 
 
 
 
321

Existence of solutions for periodic elliptic system with general superlinear nonlinearity  

Science.gov (United States)

This paper is concerned with the following elliptic system: -triangle u+V(x)u=Wv(x, u, v), quad x in {R}N, \\ -triangle v+V(x)v=Wu(x, u, v), quad x in {R}N, \\ u, v in H1({R}N), . where V and W are 1-periodic in x, and W(x,s,t) is super-quadratic in {|as+bt|} as {|as+bt|? infty} a.e. {xin {R}^N} for some a, b > 0. By using a generalized linking theorem established by Li and Szulkin, we are able to obtain the existence of nontrivial solutions under some more generic assumptions on the nonlinearity.

Liao, Fangfang; Tang, X. H.; Zhang, Jian

2014-05-01

322

Periodic and chaotic oscillations in a tumor and immune system interaction model with three delays  

Energy Technology Data Exchange (ETDEWEB)

In this paper, a tumor and immune system interaction model consisted of two differential equations with three time delays is considered in which the delays describe the proliferation of tumor cells, the process of effector cells growth stimulated by tumor cells, and the differentiation of immune effector cells, respectively. Conditions for the asymptotic stability of equilibria and existence of Hopf bifurcations are obtained by analyzing the roots of a second degree exponential polynomial characteristic equation with delay dependent coefficients. It is shown that the positive equilibrium is asymptotically stable if all three delays are less than their corresponding critical values and Hopf bifurcations occur if any one of these delays passes through its critical value. Numerical simulations are carried out to illustrate the rich dynamical behavior of the model with different delay values including the existence of regular and irregular long periodic oscillations.

Bi, Ping [Department of Mathematics, Shanghai Key Laboratory of PMMP, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Center for Partial Differential Equations, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Ruan, Shigui, E-mail: ruan@math.miami.edu [Department of Mathematics, University of Miami, Coral Gables, Florida 33124-4250 (United States); Zhang, Xinan [School of Mathematics and Statistics, Central China Normal University, Wuhan 430079 (China)

2014-06-15

323

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

324

Periodic and chaotic oscillations in a tumor and immune system interaction model with three delays  

Science.gov (United States)

In this paper, a tumor and immune system interaction model consisted of two differential equations with three time delays is considered in which the delays describe the proliferation of tumor cells, the process of effector cells growth stimulated by tumor cells, and the differentiation of immune effector cells, respectively. Conditions for the asymptotic stability of equilibria and existence of Hopf bifurcations are obtained by analyzing the roots of a second degree exponential polynomial characteristic equation with delay dependent coefficients. It is shown that the positive equilibrium is asymptotically stable if all three delays are less than their corresponding critical values and Hopf bifurcations occur if any one of these delays passes through its critical value. Numerical simulations are carried out to illustrate the rich dynamical behavior of the model with different delay values including the existence of regular and irregular long periodic oscillations.

Bi, Ping; Ruan, Shigui; Zhang, Xinan

2014-06-01

325

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

Science.gov (United States)

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. PMID:21669929

Viveros, M P; Llorente, R; Suarez, J; Llorente-Berzal, A; López-Gallardo, M; de Fonseca, F Rodriguez

2012-01-01

326

Existence and global stability of positive periodic solutions of a discrete predator-prey system with delays  

Directory of Open Access Journals (Sweden)

Full Text Available We study the existence and global stability of positive periodic solutions of a periodic discrete predator-prey system with delay and Holling type III functional response. By using the continuation theorem of coincidence degree theory and the method of Lyapunov functional, some sufficient conditions are obtained.

Pei-Hao Zhao

2004-12-01

327

Existence and global stability of positive periodic solutions of a discrete predator-prey system with delays  

Directory of Open Access Journals (Sweden)

Full Text Available We study the existence and global stability of positive periodic solutions of a periodic discrete predator-prey system with delay and Holling type III functional response. By using the continuation theorem of coincidence degree theory and the method of Lyapunov functional, some sufficient conditions are obtained.

Li Wan-Tong

2004-01-01

328

Vitrification and some properties of BaO-Nb2O5-P2O5 system glasses  

International Nuclear Information System (INIS)

The study of glasses in niobium-phosphate systems with elements of groups 1 and 2 of the Mendeleev Periodic System is continued in the given work. The system BaO-Nb2O5-P2O5 is of interest from the viewpoint of creaction on its basis of phosphate flintglasses with a high refractive index, peculiar course of relative particular dispersion in the blue (g-F') part of spectrum and low density. In system BaO-Nb2O5-P2O5 vitrification region is ascertained and range of colourless glasses is isolated, which is restricted by the content of 25-30 mol.% Nb2O5. Compositions of glasses possessing the minimum tendency to crystallization are found. It is shown that with Nb2O5 content increase the refractive index, average dispersion and density increase. It is ascertained that glasses in the system studied possess peculiar course of relative particular dispersion in the range of spectrum (g-F'). The value ?b is shifted to the short-wave range of spectrum as compared with fluorotitanium and lead-silicated flintglasses

1990-01-01

329

Periodic orbit quantization of the closed three-disk billiard as an example of a chaotic system with strong pruning  

CERN Document Server

Classical chaotic systems with symbolic dynamics but strong pruning present a particular challenge for the application of semiclassical quantization methods. In the present study we show that the technique of periodic orbit quantization by harmonic inversion of trace formulae, which does not rely on the existence of a complete symbolic dynamics or other specific properties, lends itself ideally to calculating semiclassical eigenvalues from periodic orbit data even in strongly pruned systems. As the number of periodic orbits proliferates exponentially in chaotic systems, we apply the harmonic inversion technique to cross-correlated periodic orbit sums, which allows us to reduce the required number of orbits. The power of the method is demonstrated for the closed three-disk billiard as a prime example of a classically chaotic bound system with strong pruning.

Weibert, K; Wunner, G

2002-01-01

330

Positive periodic solutions for nonautonomous impulsive neutral functional differential systems with time-varying delays on time scales  

Directory of Open Access Journals (Sweden)

Full Text Available Using a fixed point theorem of strict-set-contraction, we prove the existence of positive periodic solutions for a class of nonautonomous impulsive neutral functional differential system with time-varying delays on time scales.

Jinchun Dai

2010-03-01

331

Effect of local or systemic hydrocortisone on skin wound healing resistance, in different postoperative periods  

Directory of Open Access Journals (Sweden)

Full Text Available Objectives: To compare the resistance of skin wound healing of mice submitted to local or systemic hydrocortisone administration, in different postoperative periods. Methods: An incision and suture was performed on the thoracic skin of 130 male mice: Group 1(n = 10 resistance of the integer skin; Group 2 (n = 30 submitted only to skin incision and suture; Group 3 (n = 30 skin incision and suture followed by administration of saline fluid; Group 4(n = 30 skin incision and suture followed by administration of local hydrocortisone; Group 5 (n = 30 skin incision and suture followed by administration of systemic hydrocortisone. The resistance of the wound healing and the weight of the animals were studied on the seventh, 14th and 21st postoperative days. Histologic examination was also performed. Rresults: The mice that received corticoid (Groups 4 and 5 presented significant decreasing on their weight (p = 0.02. The Groups 3, 4 and 5 showed lower scar resistance than Group 2 on the seventh postoperative day (p 0.05. Cconclusions: Administration of hydrocortisone in mice is responsible for weight decreasing and reduction of the skin wound healing resistance during the first postoperative week.

Luiz Ronaldo Alberti

2008-09-01

332

PHYSICAL PROPERTIES OF THE 0.94-DAY PERIOD TRANSITING PLANETARY SYSTEM WASP-18  

International Nuclear Information System (INIS)

We present high-precision photometry of five consecutive transits of WASP-18, an extrasolar planetary system with one of the shortest orbital periods known. Through the use of telescope defocusing we achieve a photometric precision of 0.47-0.83 mmag per observation over complete transit events. The data are analyzed using the JKTEBOP code and three different sets of stellar evolutionary models. We find the mass and radius of the planet to be M b = 10.43 ± 0.30 ± 0.24 M Jup and R b = 1.165 ± 0.055 ± 0.014 R Jup (statistical and systematic errors), respectively. The systematic errors in the orbital separation and the stellar and planetary masses, arising from the use of theoretical predictions, are of a similar size to the statistical errors and set a limit on our understanding of the WASP-18 system. We point out that seven of the nine known massive transiting planets (M b > 3 M Jup) have eccentric orbits, whereas significant orbital eccentricity has been detected for only four of the 46 less-massive planets. This may indicate that there are two different populations of transiting planets, but could also be explained by observational biases. Further radial velocity observations of low-mass planets will make it possible to choose between these two scenarios.

2009-12-10

333

New dimensions of the periodic system: superheavy, superneutronic, superstrange, antimatter nuclei  

Science.gov (United States)

The possibilities for the extension of the periodic system into the islands of superheavy (SH) elements, to and beyond the neutron drip line and to the sectors of strangeness and antimatter are discussed. The multi-nucleon transfer processes in low-energy damped collisions of heavy actinide nuclei may help us to fill the gap between the nuclei produced in the ``hot'' fusion reactions and the continent of known nuclei. In these reactions we may also investigate the ``island of stability''. In many such collisions the lifetime of the composite giant system consisting of two touching nuclei turns out to be rather long (>=10-20 s) sufficient for observing line structure in spontaneous positron emission from super-strong electric fields (vacuum decay), a fundamental QED process not observed yet experimentally. At the neutron-rich sector near the drip line islands and extended ridges of quasistable nuclei are predicted by HF calculations. Such nuclei, as well as very long living superheavy nuclei may be provided in double atomic bomb explosions. A tremendously rich scenario of new nuclear structure emerges with new magic numbers in the strangeness domain. Various production mechanisms are discussed for these objects and for antinuclei in high energy heavy-ion collisions.

Greiner, Walter

2010-12-01

334

New dimensions of the periodic system: superheavy, superneutronic, superstrange, antimatter nuclei  

International Nuclear Information System (INIS)

The possibilities for the extension of the periodic system into the islands of superheavy (SH) elements, to and beyond the neutron drip line and to the sectors of strangeness and antimatter are discussed. The multi-nucleon transfer processes in low-energy damped collisions of heavy actinide nuclei may help us to fill the gap between the nuclei produced in the ''hot'' fusion reactions and the continent of known nuclei. In these reactions we may also investigate the ''island of stability''. In many such collisions the lifetime of the composite giant system consisting of two touching nuclei turns out to be rather long (?10-20 s); sufficient for observing line structure in spontaneous positron emission from super-strong electric fields (vacuum decay), a fundamental QED process not observed yet experimentally. At the neutron-rich sector near the drip line islands and extended ridges of quasistable nuclei are predicted by HF calculations. Such nuclei, as well as very long living superheavy nuclei may be provided in double atomic bomb explosions. A tremendously rich scenario of new nuclear structure emerges with new magic numbers in the strangeness domain. Various production mechanisms are discussed for these objects and for antinuclei in high energy heavy-ion collisions.

2010-12-23

335

SERF photovoltaic systems. Technical report on system performance for the period, August 1, 1994--July 31, 1995  

Energy Technology Data Exchange (ETDEWEB)

This report presents an analysis of performance data on the two identical, 6 kW{sub ac}, grid-connected photovoltaic systems located on the roof of the Solar Energy Research Facility building at the National Renewable Energy Laboratory in Golden, Colorado. The data cover the monitoring period August 1, 1994, to July 31, 1995, and the performance parameters analyzed include direct current and alternating current power, aperture-area efficiency, energy, capacity factor, and performance index. These parameters are compared to plane-of-array irradiance, ambient temperature, and back-of-module temperature as a function of time, either daily or monthly. We also obtained power ratings of the systems for data corresponding to different test conditions. This study has shown, in addition to expected seasonal trends, that system monitoring is a valuable tool in assessing performance and detecting faulty equipment. Furthermore, methods applied for this analysis may be used to evaluate and compare systems using cells of different technologies. The systems were both found to be operating at approximately 7% below their estimated rating, which was based on Photovoltaics for Utility-Scale Applications test conditions. This may be attributed to the design inverter efficiency being estimated at 95% compared to measured values of approximately 88%, as well as the fact that aperture-area efficiency that was overestimated at 12.8% compared to a measured value of 11.0%. The continuous monitoring also revealed faulty peak-power point tracking equipment.

Dyk, E.E. van; Strand, T.R.; Hansen, R.

1996-06-01

336

Bifurcation and complex dynamics of a two-prey two-predator system concerning periodic biological and chemical control  

International Nuclear Information System (INIS)

In this paper, we investigate the dynamic behaviors of a two-prey two-predator system with impulsive effect concerning biological and chemical control strategy-periodic releasing natural enemies and spraying pesticide at different fixed time. By applying the Floquet theory of linear periodic impulsive equation and small amplitude perturbation method, we prove that there exists a globally asymptotically stable two-prey-eradication periodic solution when the impulsive period is less than some critical value. The conditions for the permanence of the system are given, and meanwhile the conditions for the extinction of one of the two prey species and permanence of the remaining three species are given. Our results suggest a new approach in pest control. The target pest population can be driven to extinction and the non-target pest can be permanent by choosing impulsive period. With the increasing of the predation rate for the super competitor and impulsive period, the system displays complicated behaviors including a sequence of direct and inverse cascades of periodic-doubling, periodic-halfing, chaos, and symmetry breaking bifurcation

2008-07-01

337

Bifurcation and complex dynamics of a two-prey two-predator system concerning periodic biological and chemical control  

Energy Technology Data Exchange (ETDEWEB)

In this paper, we investigate the dynamic behaviors of a two-prey two-predator system with impulsive effect concerning biological and chemical control strategy-periodic releasing natural enemies and spraying pesticide at different fixed time. By applying the Floquet theory of linear periodic impulsive equation and small amplitude perturbation method, we prove that there exists a globally asymptotically stable two-prey-eradication periodic solution when the impulsive period is less than some critical value. The conditions for the permanence of the system are given, and meanwhile the conditions for the extinction of one of the two prey species and permanence of the remaining three species are given. Our results suggest a new approach in pest control. The target pest population can be driven to extinction and the non-target pest can be permanent by choosing impulsive period. With the increasing of the predation rate for the super competitor and impulsive period, the system displays complicated behaviors including a sequence of direct and inverse cascades of periodic-doubling, periodic-halfing, chaos, and symmetry breaking bifurcation.

Xiang Zhongyi [Department of Mathematics, Hubei Institute for Nationalities Hubei Enshi 445000 (China); Department of Mathematics, Xinyang Normal University Henan Xinyang 464000 (China)], E-mail: zhyxiang260@yahoo.com.cn; Song Xinyu [Department of Mathematics, Xinyang Normal University Henan Xinyang 464000 (China) and Department of Mathematics, Yuncheng College Shanxi Yuncheng 044000 (China)], E-mail: xysong88@163.com; Zhang Fengqin [Department of Mathematics, Yuncheng College Shanxi Yuncheng 044000 (China)

2008-07-15

338

Dark Periods in Rabi Oscillations of Superconducting Phase Qubit Coupled to a Microscopic Two-Level System  

CERN Document Server

We proposed a scheme to demonstrate macroscopic quantum jumps in a superconducting phase qubit coupled to a microscopic two-level system in the Josephson tunnel junction. Irradiated with suitable microwaves, the Rabi oscillations of the qubit exhibit signatures of quantum jumps: a random telegraph signal with long intervals of intense macroscopic quantum tunneling events (bright periods) interrupted by the complete absence of tunneling events (dark periods). An analytical model was developed to describe the the width of the dark periods quantitatively. The numerical simulations indicate that our analytical model captured underlying physics of the system. Besides calibrating the quality of the microscopic two-level system, our results have significance in quantum information process since dark periods in Rabi oscillations are also responsible for errors in quantum computing with superconducting qubits.

Wen, Xueda; Yu, Yang

2009-01-01

339

Exact solution for quantum dynamics of a periodically driven two-level system  

Science.gov (United States)

We present a family of exact analytic solutions for nonlinear quantum dynamics of a two-level system (TLS) subject to a periodic-in-time external field. In constructing the exactly solvable models, we use a “reverse engineering” approach where the form of external perturbation is chosen to preserve an integrability constraint, which yields a single nonlinear differential equation for the ac field. A solution to this equation is expressed in terms of Jacobi elliptic functions with three independent parameters that allows one to choose the frequency, average value, and amplitude of the time-dependent field at will. This form of the ac drive is especially relevant to the problem of dynamics of TLS charge defects that cause dielectric losses in superconducting qubits. We apply our exact results to analyze nonlinear dielectric response of such TLSs and show that the position of the resonance peak in the spectrum of the relevant correlation function is determined by the quantum-mechanical phase accumulated by the TLS wave function over a time evolution cycle. It is shown that in the nonlinear regime, this resonance frequency may be shifted strongly from the value predicted by the canonical TLS model. We also analyze the “spin” survival probability in the regime of strong external drive and recover a coherent destruction of tunneling phenomenon within our family of exact solutions, which manifests itself as a strong suppression of “spin-flip” processes and suggests that such nonlinear dynamics in LC resonators may lead to lower losses.

Gangopadhyay, Anirban; Dzero, Maxim; Galitski, Victor

2010-07-01

340

Exact solution for quantum dynamics of a periodically-driven two-level-system  

CERN Document Server

We present a family of exact analytic solutions for non-linear quantum dynamics of a two-level system (TLS) subject to a periodic-in-time external field. In constructing the exactly solvable models, we use a "reverse engineering" approach where the form of external perturbation is chosen to preserve an integrability constraint, which yields a single non-linear differential equation for the ac-field. A solution to this equation is expressed in terms of Jacobi elliptic functions with three independent parameters that allows one to choose the frequency, average value, and amplitude of the time-dependent field at will. This form of the ac-drive is especially relevant to the problem of dynamics of TLS charge defects that cause dielectric losses in superconducting qubits. We apply our exact results to analyze non-linear dielectric response of such TLSs and show that the position of the resonance peak in the spectrum of the relevant correlation function is determined by the quantum-mechanical phase accumulated by th...

Gangopadhyay, Anirban; Galitski, Victor

2010-01-01

 
 
 
 
341

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

342

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

2011-09-25

343

On The Existence of Periodic Solutions for a Certain System of Third Order Nonlinear Differential Equations  

CERN Document Server

In this paper, we study the existence and uniqueness of periodic solutions of the differential equation of the form . Here, we obtain some sufficient conditions which guarantee the existence of periodic solutions. This equation is a quite general third- order nonlinear vector differential equation, and one example is given for illustration of the subject.

Ates, Muzaffer

2011-01-01

344

Rare-Earth Elements and Their Position in the Periodic System.  

Science.gov (United States)

Contents: Previous history and the origin of problem of rare earths; History of rare-earth elements after the discovery of periodic law; Problem of position of rare-earth elements in the table in the chemical stage of development of periodic law; Physical...

D. N. Trifonov

1970-01-01

345

Identifying parameters of multi-degree-of-freedom nonlinear structural dynamic systems using linear time periodic approximations  

Science.gov (United States)

The authors recently presented a new nonlinear system identification method, here dubbed the NL-LTP method, in which the system of interest is forced harmonically so that it responds in a stable periodic orbit, and then it is perturbed slightly and its response is recorded as it returns to the orbit. Under mild assumptions the response about the periodic orbit can be approximated using a linear time periodic system model, which can be identified from the measurements using techniques that are akin to linear modal analysis. While the prior work focused on simulated measurements from single degree-of-freedom systems, this work presents several tools that are needed in order to use this approach on multi-degree-of-freedom systems and focuses on applying the method to experimental hardware. The proposed system identification methodology is unique in that it identifies both the order of the nonlinear system and a mathematical model for the nonlinear restoring forces without assuming the mathematical form for the nonlinearities a priori. Towards these ends, this work explains how to extract the underlying nonlinear system model, or nonlinear restoring force versus displacement relationships, from the time periodic model that governs deviations of the system from its periodic orbit, and presents various metrics that can be used to determine which terms in the model are meaningful. These new tools are used to apply the identification method to a continuous, multi-degree-of-freedom structure with a discrete geometric nonlinearity, using both simulated and experimental measurements. The experimental hardware consists of a cantilever beam with a nonlinear spring attached to its tip, which is driven in a periodic limit cycle by an electromagnetic shaker.

Sracic, Michael W.; Allen, Matthew S.

2014-06-01

346

Study periods and energy price escalation rates: important factors in the economic evaluation of insulation systems  

Energy Technology Data Exchange (ETDEWEB)

The study period length and energy price escalation rate are two basic assumptions that must be established prior to the application of an economic evaluation technique. The study period length (the time period over which the costs of an investment are analyzed) may reflect the useful life of the investment or the time horizon of the investor. The energy price escalation rate (the rate of cost increase assumed for a given type of energy) will reflect the investor's expected inflation rate for energy costs. Presented here are a number of graphically illustrated examples that give detailed sensitivity analyses for varied study period lengths and energy price escalation rates. It is shown that the calculated cost-effectiveness of an investment in insulation can be extremely dependent upon the study period length and energy price escalation rate selected for the economic evaluation.

Albrecht, R.J.

1983-01-01

347

Positive periodic solution of a general discrete non-autonomous difference system of plankton allelopathy with delays  

Science.gov (United States)

The main purpose of this paper is to investigate a discrete time non-autonomous difference system of plankton allelopathy with delays. By employing continuous theorem proposed by Gains and Mawhin and some new techniques, a set of verifiable sufficient criteria are established for the existence of at least one strictly positive (componentwise) periodic solution, and as an application, we also examine some special case, showing that these conditions are similar to those of continuous differential system. It is also shown that the time delays are harmless for the existence of positive periodic solutions of system.

Liu, Zhijun; Chen, Lansun

2006-12-01

348

Existence and stability of almost periodic solutions of nonautonomous competitive systems with weak Allee effect and delays  

Science.gov (United States)

In this paper, a class of nonautonomous Lotka-Volterra type multispecies competitive systems with weak Allee effect and delays are considered. By using Mawhin's continuation theorem of coincidence degree theory, we obtain some sufficient conditions for the existence of almost periodic solutions for the Lotka-Volterra system. On the case of no delays of Allee effects, by constructing a suitable Lyapunov function, we get a sufficient condition for the globally attractivity of the almost periodic solution for the Lotka-Volterra system. Moreover, we also present an illustrative example to show the effectiveness of our results.

Wu, Wanqin; Ye, Yuan

2009-11-01

349

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

International Nuclear Information System (INIS)

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

350

New soliton-like and periodic solution of (2 + 1)-dimensional higher order Broer-Kaup system  

International Nuclear Information System (INIS)

In this paper, the (2 + 1)-dimensional higher order Broer-Kaup system is reduced to a simple nonlinear partial differential equation by a transformation. Based on the single equation and utilizing new generally projective Riccati equation method, we obtain many new exact solutions for the (2 + 1)-dimensional higher order Broer-Kaup system, including new soliton-like solutions and periodic solutions

2004-11-01

351

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

2010-10-01

352

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Kukushkin, I. V.; Akimov, M. Yu; Smet, J. H.; Mikhailov, S. A.; Von Klitzing, K.; Aleiner, I. L.; Falko, V. I.

2003-01-01

353

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

2008-12-01

354

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

Energy Technology Data Exchange (ETDEWEB)

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.

Zhang Long [College of Mathematics and System Sciences, Xinjiang University, Urumqi 830046 (China)], E-mail: longzhang_xj@sohu.com; Teng Zhidong [College of Mathematics and System Sciences, Xinjiang University, Urumqi 830046 (China)], E-mail: zhidong@xju.edu.cn

2008-12-15

355

Transient flow analysis in reactor coolant pump systems during flow coastdown period  

International Nuclear Information System (INIS)

The rapid flow transient calculation in reactor coolant pump system is important in the safety analysis of a nuclear reactor. An accurate transient analysis of flow coastdown is also important and necessary for the design and manufacture of a reactor coolant pump. Only under the reliable work of a reactor coolant pump the safety of a nuclear power plant can be guaranteed. A mathematical model is developed for solving flow rate transient and pump speed transient during flow coastdown period. The detailed information of the centrifugal pump characteristics is not required. The flow rate and pump speed are solved analytically. The analytic solution of non-dimensional flow rate indicates that non-dimensional flow rate is determined by energy ratio ?. The kinetic energy of the loop coolant fluid and the kinetic energy stored in the rotating parts are two important parameters in form of ?. When the steady-state flow rate and pump speed are constant, the inertia of primary loop fluid and the pump moment of inertia are also two important parameters in flow transient analysis. For the condition all pump shafts are seized, the flow decay depends on the inertia of primary loop fluid. For the case that pump inertia is very large, the flow decay is determined by the pump inertia. The calculated non-dimensional flow rate and non-dimensional pump speed using the model are compared with published experimental data of two nuclear power plants and a reactor model test on flow coastdown transients. The comparison results show a good agreement. As the flow rate approaches to zero, the increase difference between experimental and calculated value is due to the effect of the mechanical friction loss.

2011-02-01

356

Transient flow analysis in reactor coolant pump systems during flow coastdown period  

Energy Technology Data Exchange (ETDEWEB)

The rapid flow transient calculation in reactor coolant pump system is important in the safety analysis of a nuclear reactor. An accurate transient analysis of flow coastdown is also important and necessary for the design and manufacture of a reactor coolant pump. Only under the reliable work of a reactor coolant pump the safety of a nuclear power plant can be guaranteed. A mathematical model is developed for solving flow rate transient and pump speed transient during flow coastdown period. The detailed information of the centrifugal pump characteristics is not required. The flow rate and pump speed are solved analytically. The analytic solution of non-dimensional flow rate indicates that non-dimensional flow rate is determined by energy ratio {beta}. The kinetic energy of the loop coolant fluid and the kinetic energy stored in the rotating parts are two important parameters in form of {beta}. When the steady-state flow rate and pump speed are constant, the inertia of primary loop fluid and the pump moment of inertia are also two important parameters in flow transient analysis. For the condition all pump shafts are seized, the flow decay depends on the inertia of primary loop fluid. For the case that pump inertia is very large, the flow decay is determined by the pump inertia. The calculated non-dimensional flow rate and non-dimensional pump speed using the model are compared with published experimental data of two nuclear power plants and a reactor model test on flow coastdown transients. The comparison results show a good agreement. As the flow rate approaches to zero, the increase difference between experimental and calculated value is due to the effect of the mechanical friction loss.

Gao Hong, E-mail: hgao@sjtu.edu.c [Institute of Design and Control Engineering for Heavy Equipment, State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, No. 800 Dong Chuan Road, Shanghai 200240 (China); Gao Feng; Zhao Xianchao; Chen Jie; Cao Xuewu [Institute of Design and Control Engineering for Heavy Equipment, State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, No. 800 Dong Chuan Road, Shanghai 200240 (China)

2011-02-15

357

Critical experiments on an enriched uranium solution system containing periodically distributed strong thermal neutron absorbers  

International Nuclear Information System (INIS)

A series of 62 critical and critical approach experiments were performed to evaluate a possible novel means of storing large volumes of fissile solution in a critically safe configuration. This study is intended to increase safety and economy through use of such a system in commercial plants which handle fissionable materials in liquid form. The fissile solution's concentration may equal or slightly exceed the minimum-critical-volume concentration; and experiments were performed for high-enriched uranium solution. Results should be generally applicable in a wide variety of plant situations. The method is called the 'Poisoned Tube Tank' because strong neutron absorbers (neutron poisons) are placed inside periodically spaced stainless steel tubes which separate absorber material from solution, keeping the former free of contamination. Eight absorbers are investigated. Both square and triangular pitched lattice patterns are studied. Ancillary topics which closely model typical plant situations are also reported. They include the effect of removing small bundles of absorbers as might occur during inspections in a production plant. Not taking the tank out of service for these inspections would be an economic advantage. Another ancillary topic studies the effect of the presence of a significant volume of unpoisoned solution close to the Poisoned Tube Tank on the critical height. A summary of the experimental findings is that boron compounds were excellent absorbers, as expected. This was true for granular materials such as Gerstley Borate and Borax; but it was also true for the flexible solid composed of boron carbide and rubber, even though only thin sheets were used. Experiments with small bundles of absorbers intentionally removed reveal that quite reasonable tanks could be constructed that would allow a few tubes at a time to be removed from the tank for inspection without removing the tank from production service

1996-01-01

358

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

Science.gov (United States)

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. PMID:21384944

Lorenz, Marco; Usvyat, Denis; Schütz, Martin

2011-03-01

359

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 e?cient and parallel implementation of periodic local second order Møller-Plesset perturbation theory (MP2), which allows to study 1D-, 2D- and 3D-periodic sy...

Erba, Alessandro; Maschio, Lorenzo; Casassa, Silvia Maria; Pisani, Cesare

2012-01-01

360

Periodic Semifolded Solitary Waves for (2+1)-Dimensional Variable Coefficient Broer-Kaup System  

International Nuclear Information System (INIS)

Applying the extended mapping method via Riccati equation, many exact variable separation solutions for the (2+1)-dimensional variable coefficient Broer-Kaup equation are obtained. Introducing multiple valued function and Jacobi elliptic function in the seed solution, special types of periodic semifolded solitary waves are derived. In the long wave limit these periodic semifolded solitary wave excitations may degenerate into single semifolded localized soliton structures. The interactions of the periodic semifolded solitary waves and their degenerated single semifolded soliton structures are investigated graphically and found to be completely elastic

2008-06-15

 
 
 
 
361

Periodic Semifolded Solitary Waves for (2+1)-Dimensional Variable Coefficient Broer Kaup System  

Science.gov (United States)

Applying the extended mapping method via Riccati equation, many exact variable separation solutions for the (2+1)-dimensional variable coefficient Broer Kaup equation are obtained. Introducing multiple valued function and Jacobi elliptic function in the seed solution, special types of periodic semifolded solitary waves are derived. In the long wave limit these periodic semifolded solitary wave excitations may degenerate into single semifolded localized soliton structures. The interactions of the periodic semifolded solitary waves and their degenerated single semifolded soliton structures are investigated graphically and found to be completely elastic.

Huang, Wen-Hua

2008-06-01

362

Hybrid coupled-cluster and perturbation method for extended systems of one-dimensional periodicity.  

Science.gov (United States)

A hybrid of the coupled-cluster singles and doubles (CCSD) and second-order Møller-Plesset perturbation (MP2) methods [M. Nooijen, J. Chem. Phys. 111, 10815 (1999); A. D. Bochevarov and C. D. Sherrill, ibid. 122, 234110 (2005); A. D. Bochevarov et al., ibid. 125, 054109 (2006)] is formulated and implemented for one-dimensional periodic extended systems, in which the excitation (T) amplitudes of active bands are determined iteratively by CCSD, while the T amplitudes of mixed active/inactive bands are held fixed at the first-order Møller-Plesset perturbation values. The occupied and virtual bands near the Fermi level, which can cause instability in MP2 when they are (quasi-)degenerate, are selected as active bands to be treated by CCSD, which can, in principle, resist such instability. Two contraction schemes of the T amplitudes (Contractions A and B) are considered. Contraction A is the one proposed for molecules and used also for extended systems because it is efficient for CCSD, but not necessarily so for the hybrid CCSD/MP2. Contraction B is introduced to be more optimally efficient for the hybrid CCSD/MP2 by maximizing the number of intermediate quantities made of the inactive T amplitudes and molecular integrals, which do not vary during CCSD iterations and are computed only once, stored, and reused. In an application to trans-polyacetylene, a smooth transition of the results of the hybrid CCSD/MP2 is observed toward those of CCSD and MP2 by increasing and decreasing, respectively, the number of active bands. With the smallest active space, the hybrid CCSD/MP2 with Contractions A and B achieves a speedup by a factor of 360 and 520, respectively, relative to CCSD. When all of the occupied bands and about half of the virtual bands are active, the hybrid CCSD/MP2 can recover 98% of the CCSD correlation energy or half of the difference between CCSD and MP2 at less than a tenth of the usual CCSD cost. PMID:21913754

Ohnishi, Yu-ya; Hirata, So

2011-09-01

363

Emergency Diesel Generation System Surveillance Test Policy Optimization Through Genetic Algorithms Using Non-Periodic Intervention Frequencies and Seasonal Constraints  

International Nuclear Information System (INIS)

Nuclear standby safety systems must frequently, be submitted to periodic surveillance tests. The main reason is to detect, as soon as possible, the occurrence of unrevealed failure states. Such interventions may, however, affect the overall system availability due to component outages. Besides, as the components are demanded, deterioration by aging may occur, penalizing again the system performance. By these reasons, planning a good surveillance test policy implies in a trade-off between gains and overheads due to the surveillance test interventions. In order maximize the systems average availability during a given period of time, it has recently been developed a non-periodic surveillance test optimization methodology based on genetic algorithms (GA). The fact of allowing non-periodic tests turns the solution space much more flexible and schedules can be better adjusted, providing gains in the overall system average availability, when compared to those obtained by an optimized periodic tests scheme. The optimization problem becomes, however, more complex. Hence, the use of a powerful optimization technique, such as GAs, is required. Some particular features of certain systems can turn it advisable to introduce other specific constraints in the optimization problem. The Emergency Diesel Generation System (EDGS) of a Nuclear Power Plant (N-PP) is a good example for demonstrating the introduction of seasonal constraints in the optimization problem. This system is responsible for power supply during an external blackout. Therefore, it is desirable during periods of high blackout probability to maintain the system availability as high as possible. Previous applications have demonstrated the robustness and effectiveness of the methodology. However, no seasonal constraints have ever been imposed. This work aims at investigating the application of such methodology in the Angra-II Brazilian NPP EDGS surveillance test policy optimization, considering the blackout probability growth during summer, due to the electrical power demand increase. Here, the model used penalizes test interventions by a continuous modulating function, which depends on the instantaneous blackout probability. Results have demonstrated the ability of the method in adapting the surveillance tests policy to seasonal behaviors. The knowledge acquired by the GA during the searching process has lead to test schedules that drastically minimize the test interventions at periods of high blackout probability. It is compensated by more frequent tests redistributed through the periods of low blackout probability, in order to provide improvement on the overall average availability at the system level. (authors)

2002-04-14

364

Periodic Solutions of Impulsive Predator?prey System With Time?Varying ?Delays and Watt?Type Functional Response  

Directory of Open Access Journals (Sweden)

Full Text Available Delay phenomenon and pulse effects in biological systems exist widespread. Because taking into account the ecological system with time?delay and pulse effect is of great theoretical and practical significance, a class model of impulsive predator?prey system with variable delays and Watt type functional response is considered in this paper. By using the differential inequality comparison with pulse, the continuation theorem of coincidence degree theory, homotopy invariance property, some sufficient conditions ensuring the existence of positive periodic solutions of the system are obtained. That is, there is at least one positive periodic solution for the impulsive system if one of the following conditions is satisfied. And prior bounds are given to keep these qualities of the system. The results improve and extend some recent works.

YANG Zhi-chun

2012-09-01

365

Photometric study of the short period W UMa system VW Cephei  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A total of 431 photoelectric B and V observations are presented for the short period . The measurements have been obtained in two successive nights, 27/28 and 28/29 of September 1995, and represent the whole light curve phases. Four times of minimum light, for each filter, were deduced and new periods have been derived as 0.277892 day from the present photometric observations. New light curves have been constructed, investigated and analyzed by using the recent version of W-...

Essam, A.; Alawy, A. E.; Haroon, A. A.

2014-01-01

366

Weed populations and crop rotations : Exploring dynamics of a structured periodic system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The periodic growing of a certain set of crops in a prescribed order, called a crop rotation, is considered to be an important tool for managing weed populations. Nevertheless, the effects of crop rotations on weed population dynamics are not well understood. Explanations for rotation effects on weed populations usually invoke the diversity of environments caused by different crops that a weed population encounters. Using a periodic matrix model, we show that the number of different crops is ...

Mertens, S. K.; Bosch, F. Den; Heesterbeek, J. A. P.

2002-01-01

367

A simple phenomenologic model for particle transport in space-periodic potentials in underdamped systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We consider the motion of an underdamped Brownian particle in a tilted periodic potential in a wide temperature range. Based on the previous data [1] and the new simulation results we show that the underdamped motion of particles in space-periodic potentials can be considered as the overdamped motion in the velocity space in the effective double-well potential. Simple analytic expressions for the particle mobility and diffusion coefficient have been derived with the use of t...

Marchenko, I. G.; Marchenko, I. I.; Zhiglo, A. V.

2013-01-01

368

Electrostatic Interactions in Finite Systems treated with Periodic Boundary Conditions: Application to Linear-Scaling Density Functional Theory  

CERN Document Server

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 ...

Hine, N D M; Haynes, P D; Skylaris, C K

2011-01-01

369

Cogging effect minimization in PMSM position servo system using dual high-order periodic adaptive learning compensation.  

Science.gov (United States)

Cogging effect which can be treated as a type of position-dependent periodic disturbance, is a serious disadvantage of the permanent magnetic synchronous motor (PMSM). In this paper, based on a simulation system model of PMSM position servo control, the cogging force, viscous friction, and applied load in the real PMSM control system are considered and presented. A dual high-order periodic adaptive learning compensation (DHO-PALC) method is proposed to minimize the cogging effect on the PMSM position and velocity servo system. In this DHO-PALC scheme, more than one previous periods stored information of both the composite tracking error and the estimate of the cogging force is used for the control law updating. Asymptotical stability proof with the proposed DHO-PALC scheme is presented. Simulation is implemented on the PMSM servo system model to illustrate the proposed method. When the constant speed reference is applied, the DHO-PALC can achieve a faster learning convergence speed than the first-order periodic adaptive learning compensation (FO-PALC). Moreover, when the designed reference signal changes periodically, the proposed DHO-PALC can obtain not only faster convergence speed, but also much smaller final error bound than the FO-PALC. PMID:20605022

Luo, Ying; Chen, Yangquan; Pi, Youguo

2010-10-01

370

OBGMX: a web-based generator of GROMACS topologies for molecular and periodic systems using the universal force field.  

Science.gov (United States)

OBGMX is a web service providing topologies for the GROMACS molecular dynamics software package according to the Universal Force Field, as implemented in the Open Babel package. OBGMX can deal with molecular and periodic systems. The geometrical parameters appearing in the potential energy functions for the bonded interactions can be set to those measured in the input configuration. The performance of OBGMX in reproducing the structure of periodic systems is analyzed by calculating the root mean-squared displacements of optimized configurations of a large set of metal-organic frameworks. OBGMX is available at http://software-lisc.fbk.eu/obgmx/. PMID:22718537

Garberoglio, Giovanni

2012-10-15

371

Permanence and periodic solutions for an impulsive reaction-diffusion food-chain system with ratio-dependent functional response  

Science.gov (United States)

An impulsive reaction-diffusion periodic food-chain system with ratio-dependent functional response is investigated in the present paper. Sufficient conditions for the ultimate boundedness and permanence of the food-chain system are established based on the comparison theory of differential equation and upper and lower solution method. By constructing appropriate auxiliary function, the conditions for the existence of a unique globally stable positive periodic solution are also obtained. Some numerical examples are presented to verify our results. A discussion is given in the end of the paper.

Liu, Zijian; Zhong, Shouming; Liu, Xiaoyun

2014-01-01

372

YIELD AND CHOSEN QUALITY TRAITS OF OAT GROWN IN THE PERIOD OF CONVERSION TO ORGANIC CROPPING SYSTEM  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the period of 2004-2005 researches were done at the Agricultural Experimental Station in Ba?cyny (53o35’ N; 19o51’ E) of the University of Warmia and Mazury to determine the results of conversion of oat growing from the conventional system to the organic one. In the first crop rotation it was cultivated according to the principles of the conventional cropping system, applying mineral fertilizers and pesticides. In the second one, a two-year period of conversion of crops to the organic...

2009-01-01

373

Mutual Inhibition, Competition, and Periodicity in a Two Species Chemostat-like System  

Directory of Open Access Journals (Sweden)

Full Text Available A model addressing mutual inhibition in a peiodic chemostat is presented in this paper. The operating parameters, including the nutirent uptake function, washout rate, and nutrient concentration are allowed to be periodic functions of time, with comensurate periods. It is shown that with mutual inhibition, competitive exclusion always holds in models that would allow coexistence without inhibition. We further show that initial conditions play a crucial role in determining which species survives. Simulations using MATLAB appear to confirm the predictions of the models. Some results from the simulations are presented graphically.

George Kimathi

2012-05-01

374

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

375

Gaps in the spectrum of the Neumann Laplacian generated by a system of periodically distributed trap  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The article deals with a convergence of the spectrum of the Neumann Laplacian in a periodic unbounded domain $\\Omega^\\varepsilon$ depending on a small parameter $\\varepsilon>0$. The domain has the form $\\Omega^\\varepsilon=\\mathbb{R}^n\\setminus S^\\varepsilon$, where $S^\\varepsilon$ is an $\\varepsilon\\mathbb{Z}^n$-periodic family of trap-like screens. We prove that for an arbitrarily large $L$ the spectrum has just one gap in $[0,L]$ when $\\varepsilon$ small enough, moreover w...

Khrabustovskyi, Andrii; Khruslov, Evgeni

2013-01-01

376

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

377

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.

Jiezhong Zou

2005-09-01

378

Generalized synchronization in the action of a chaotic signal on a periodic system  

Science.gov (United States)

Generalized synchronization is observed during the action of a chaotic signal on generators of periodic oscillations. The features in the behavior of the synchronous regime threshold upon a change in the chaotic signal parameters are investigated. The possibility of using such devices for concealed information transfer is demonstrated.

Koronovskii, A. A.; Moskalenko, O. I.; Pavlov, A. S.; Frolov, N. S.; Hramov, A. E.

2014-05-01

379

Note: Optimal base-stock policy for the inventory system with periodic review, backorders and sequential lead times  

DEFF Research Database (Denmark)

We show that well-known textbook formulae for determining the optimal base stock of the inventory system with continuous review and constant lead time can easily be extended to the case with periodic review and stochastic, sequential lead times. The provided performance measures and conditions for optimality are exact.

Johansen, Søren Glud; Thorstenson, Anders

2006-01-01

380

Optimal base-stock policy for the inventory system with periodic review, backorders and sequential lead times  

DEFF Research Database (Denmark)

We extend well-known formulae for the optimal base stock of the inventory system with continuous review and constant lead time to the case with periodic review and stochastic, sequential lead times. Our extension uses the notion of the 'extended lead time'. The derived performance measures are exact for Poisson demands.

Johansen, Søren Glud; Thorstenson, Anders

2008-01-01

 
 
 
 
381

A simple global representation for second-order normal forms of Hamiltonian systems relative to periodic flows  

International Nuclear Information System (INIS)

We study the determination of the second-order normal form for perturbed Hamiltonians relative to the periodic flow of the unperturbed Hamiltonian H0. The formalism presented here is global, and can be easily implemented in any computer algebra system. We illustrate it by means of two examples: the Hénon–Heiles and the elastic pendulum Hamiltonians. (paper)

2013-10-04

382

Optimal base-stock policy for the inventory system with periodic review, backorders and sequantial lead times  

DEFF Research Database (Denmark)

We extend well-known formulae for the optimal base stock of the inventory system with continuous review and constant lead time to the case with periodic review and stochastic, sequential lead times. Our extension uses the notion of the â??extended lead timeâ??. The derived performance measures are exact for Poisson demands.

Johansen, Søren Glud; Thorstenson, Anders

2008-01-01

383

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

Science.gov (United States)

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.; Chauhan, Shashank; Hansen, Morten Hartvig

2011-05-01

384

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

2011-04-01

385

Optimal unit commitment of the power system in Bulgaria during the transitional period to power wholesale market  

International Nuclear Information System (INIS)

The paper presents a procedure for optimal one year unit commitment in Bulgarian electric power system during the transitional period to wholesale market, combining certain classical theoretical models with heuristic methods. Comments are made on the transition from yearly commitment to weekly and daily dispatching control. The stages of the theory and practices for results optimality

2001-01-01

386

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

Science.gov (United States)

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.

Khamzin, A. A.; Nigmatullin, R. R.; Popov, I. I.; Zhelifonov, M. P.

2012-11-01

387

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

International Nuclear Information System (INIS)

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

388

Phase Behavior of Two-Dimensional Colloidal Systems in the Presence of Periodic Light Fields  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate the phase behavior of a two-dimensional suspension of charge stabilized polystyrene spheres in the presence of a one-dimensional periodic light field. With increasing light intensity we observe a liquid-solid followed by a solid-liquid transition which are known as laser-induced freezing and melting, respectively. Here we report on measurements where, in addition to the light intensity, the single particle density was also systematically varied. As a result, we obtain for the f...

2001-01-01

389

Noise-Induced Phase Space Transport in Time-Periodic Hamiltonian Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Orbits in a three-dimensional potential subjected to periodic driving, V(x^i,t)=[1+m_0 sin(omega t) V_0(x^i), divide naturally into two types, regular and chaotic, between which transitions are seemingly impossible. The chaotic orbits divide in turn into two types, apparently separated by entropy barriers, namely `sticky' orbit segments, which are `locked' to the driving frequency and exhibit little systematic energy diffusion, and `wildly' chaotic segments, which are not so...

Terzic, Balsa; Kandrup, Henry E.

2003-01-01

390

The existence of periodic orbits and invariant tori for some 3-dimensional quadratic systems.  

Science.gov (United States)

We use the normal form theory, averaging method, and integral manifold theorem to study the existence of limit cycles in Lotka-Volterra systems and the existence of invariant tori in quadratic systems in ?(3). PMID:24982980

Jiang, Yanan; Han, Maoan; Xiao, Dongmei

2014-01-01

391

Stabilizing periodic orbits of chaotic systems using fuzzy control of Poincare map  

International Nuclear Information System (INIS)

In this paper a fuzzy control algorithm is used to stabilize the fixed points of a chaotic system. No knowledge of the dynamic equations of the system is needed in this approach and the whole system is considered as a black box. Two main approaches have been investigated: fuzzy clustering and table look up methods. As illustrative examples these methods have been applied to Bonhoeffer van der Pol oscillator and the Henon chaotic system and the convergence toward fixed points is observed

2008-05-01

392

Dynamic Scheduling of Skippable Periodic Tasks with Energy Efficiency in Weakly Hard Real-Time System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Santhi Baskaran,; Thambidurai, P.

2010-01-01

393

Qualitative control of periodic solutions in piecewise affine systems; application to genetic networks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Hybrid systems, and especially piecewise affine (PWA) systems, are often used to model gene regulatory networks. In this paper we elaborate on previous work about control problems for this class of models, using also some recent results guaranteeing the existence and uniqueness of limit cycles, based solely on a discrete abstraction of the system and its interaction structure. Our aim is to control the transition graph of the PWA system to obtain an oscillatory behaviour, which is indeed of p...

Farcot, Etienne; Gouze?, Jean-luc

2009-01-01

394

Qualitative control of periodic solutions in piecewise affine systems; application to genetic networks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Hybrid systems, and especially piecewise affine (PWA) systems, are often used to model gene regulatory networks. In this paper we elaborate on previous work about control problems for this class of models, using also some recent results guaranteeing the existence and uniqueness of limit cycles, based solely on a discrete abstraction of the system and its interaction structure. Our aim is to control the transition graph of the PWA system to obtain an oscillatory behaviour, wh...

Farcot, Etienne; Gouze?, Jean-luc

2009-01-01

395

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

2010-12-01

396

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A physalis (Physalis peruviana) é uma pequena fruta com grandes potencialidades, que, associadas ao seu ciclo curto e às propriedades nutracêuticas, apresenta possibilidade de alto retorno econômico. O objetivo deste trabalho foi avaliar o sistema de tutoramento e a época de transplante mais adequad [...] os para o crescimento e a produção de frutos de P. peruviana nas condições edafoclimáticas do sul do Rio Grande do Sul. O trabalho foi desenvolvido em Pelotas, RS, na safra de 2007/2008. O transplante de mudas de physalis foi realizado em duas épocas (época 1, 21/11/2007 e época 2 15/01/2008), sendo as plantas tutoradas em quatro sistemas de condução (sistema "V" invertido, sistema triangular, sistema vertical com bambu e sistema vertical com fitilho), semelhantes aos utilizados na cultura do tomateiro. O delineamento experimental adotado foi de blocos casualizados, com três repetições, sendo cada um representado por dez plantas. Os tratamentos formaram um fatorial 2x4 (épocas de transplante x sistemas de tutoramento). As variáveis analisadas foram: incremento do comprimento e da área da seção do ramo principal, área da seção do ramo principal, produtividade e eficiência produtiva. Foi evidenciado que a primeira época de transplante associada aos sistemas de tutoramento "V" invertido e triangular proporciona melhor desempenho agronômico das plantas de physalis. Abstract in english The cape-gooseberry (Physalis peruviana) is a small fruit with great potentialities that whether associated to its short cycle and nutraceutical properties it shows high economical return. The work aimed to evaluate the best training system and replant period to plant growth, production and fruit qu [...] ality of P. peruviana under edaphoclimatic at conditions of southern Rio Grande do Sul. The trial was carried out in Pelotas, RS, in 2007/2008 crop. Transplanting seedlings cape-gooseberry was conducted in two seasons Plant replanting was done in two periods (period 1, 21/11/2007 and period 2, 15/01/2008). Plants were trained under four systems (inverted "V" system, triangular system, vertical system using bamboo or vertical system using polypropylene cord), similarly to the tomato culture. Experimental design adopted was a complete randomized block in a 2x4 factorial (replant period x training system) with three replications of ten plants each. The variables analyzed were: increment of length and section area of the main branch, section area of the main branch, yield and yield efficiency. It was evidenced that the first period of replant associated to the training systems inverted "V" and triangular improved the agronomical performance of cape-gooseberry plants.

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

397

Progress report of the CEC project Rodos system development. Period: 1 september 92-31 august 93; Rapport d`avancement du projet europeen Rodos ``developpement du systeme``. Periode du 1er septembre 1992 au 31 aout 1993  

Energy Technology Data Exchange (ETDEWEB)

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.

Marchand, O.

1994-12-31

398

A Phase-Locked Loop Model of the Response of the Postural Control System to Periodic Platform Motion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A phase-locked loop (PLL) model of the response of the postural control system to periodic platform motion is proposed. The PLL model is based on the hypothesis that quiet standing (QS) postural sway can be characterized as a weak sinusoidal oscillation corrupted with noise. Because the signal to noise ratio is quite low, the characteristics of the QS oscillator are not measured directly from the QS sway, instead they are inferred from the response of the oscillator to periodic motion of the ...

Schilling, Robert J.; Robinson, Charles J.

2010-01-01

399

Calibrated simulation of a solar hot water system to match degraded performance over a 22-year period using two models  

Energy Technology Data Exchange (ETDEWEB)

This paper reports on the measured performance of a residential solar water heating system over a period of 22 years and the modeling of the system to simulate its degradation over that period. The system consists of three fixed flat-plate collectors with a total of 5 m{sup 2} of double-layer glass cover plates and black aluminum fin-tube absorber plates. The solar storage tank capacity is 303 L, which is used as a pre-heater to a 114-L conventional electric water heater. Measurements and simulations indicate that fogging of the glass cover plates has reduced the transmissivity by around 63% over the 22 years. (author)

Degelman, Larry O. [Texas A and M University, College Station, TX (United States)

2008-04-15

400

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

Science.gov (United States)

Extending previous results of Oh-Zumbrun and Johnson-Zumbrun, we show that spectral stability implies linearized and nonlinear stability of spatially periodic traveling wave solutions of viscous systems of conservation laws for systems of generic type, removing a restrictive assumption that wave speed be constant to first order along the manifold of nearby periodic solutions. Key to our analysis is a nonlinear cancellation estimate observed by Johnson and Zumbrun, along with a detailed understanding of the Whitham averaged system. The latter motivates a careful analysis of the Bloch perturbation expansion near zero frequency and suggests factoring out an appropriate translational modulation of the underlying wave, allowing us to derive the sharpened low-frequency estimates needed to close the nonlinear iteration arguments.

Johnson, Mathew A.; Zumbrun, Kevin

 
 
 
 
401

Stability of non-sticking periodic oscillations obtained via the averaging method in discontinuous systems. I. Smooth outside of the discontinuity surfaces systems  

CERN Multimedia

In this paper the statement of the second Bogolyubov's theorem on periodic solutions of smooth systems with small parameter is justified for discountinuous systems. It is assumed that the generating solution intersects the discontinuity hyperplanes transversally and that the system is smooth outside of these hyperplanes. Such a situation is natural for mechanical systems with dry friction and without constraints and sticking of oscillations. To illustrate the result we prove stability of the velocity of vibration-induced displacement.

Makarenkov, Oleg

2008-01-01

402

Performance of wetland systems in the treatment of sewage generated at an educational institution, after a recession period  

Directory of Open Access Journals (Sweden)

Full Text Available Education institutions are potential generators of large volumes of domestic sewage. Studies of natural systems for effluent treatment have shown good efficiency and low cost compared to traditional systems. This makes them suitable for various segments of society, including educational institutions. A characteristic shared by most educational institutions is that they have the same academic calendars that include a long period of recess when, in many cases, the flow of sewage systems drops to almost zero, causing damage to both macrophytes in sewage bed and their associated microorganisms. This study aimed to evaluate the efficiency of a wetland system in an educational institution, after the recess period. It was observed for 45 days if there were signs of natural recovery, without any intervention. After this period, 15 seedlings of Thypha sp. were planted in the sewage bed, and analyses were performed for 45 additional days. The system efficiency in reducing turbidity, NH3, NO3- and phosphorus was, respectively, 63.0%, 21.7%, 31.1% and 20.3%, and for BOD, COD and thermotolerant coliforms, the average efficiency was 46.0%, 29.7% and 44.0%, respectively. If considered only the period after planting the results improved, with the following results: turbidity = 78.2%, 38.0% = NH3, NO3- = 53.2% = 25.6% phosphorus, BOD = 66, 2% = 36.5% COD and thermotolerant coliform = 60.7%. The results demonstrated the importance of vegetation bed for the efficiency of such treatment system.

Paulo Fortes Neto

2011-12-01

403

Resonance and frequency-locking phenomena in spatially extended phytoplankton–zooplankton system with additive noise and periodic forces  

International Nuclear Information System (INIS)

It is known that natural systems are undeniably subject to random fluctuations, arising from either environmental variability or internal effects. In this paper, we present a spatial version of the phytoplankton–zooplankton model that includes some important factors such as external periodic forces, noise, and diffusion processes. The spatially extended phytoplankton–zooplankton system is from the original study by Scheffer (Scheffer 1991 Oikos 62 271). Our results show that the spatially extended system exhibits a resonant pattern and frequency-locking phenomena. The system also shows that the noise and the external periodic forces play a constructive role in the Scheffer's model: (i) the noise can enhance the oscillation of phytoplankton species' density and form large clusters in space when the noise intensity is within a certain interval; (ii) the external periodic forces can induce 4:1 and 1:1 frequency-locking and spatially homogeneous oscillation phenomena to appear; and (iii) resonant patterns are observed in the system when the spatial noises and external periodic forces are both turned on. Moreover, we find that the 4:1 frequency locking transforms into 1:1 frequency locking when the noise intensity is increased. In addition to elucidating our results outside the domain of Turing instability, we provide further analysis of linear stability with the help of numerical calculation using the Maple software. Significantly, oscillations are enhanced in the system when the noise term is present. These results indicate that the oceanic plankton bloom may be partly due to interplay between the stochastic factors and external forces instead of deterministic factors. These results also may help us to understand the effects arising from the undeniable susceptibility to random fluctuations in oceanic plankton bloom

2008-05-01

404

IMPACT ON THE EVOLUTION OF THE INTERNATIONAL SYSTEM OF TAXATION AND CUSTOMS OF ROMANIAN MODERN AND CONTEMPORARY PERIOD (1859 - 2013  

Directory of Open Access Journals (Sweden)

Full Text Available Since the formation of the United Principalities (24/01/1859, Romania has undergone a series of profound, permanent reforms of its fundamental institutions. The international context had an influence important, often enteritis in shaping its institutions, including the system of taxes. We plan to make a brief review of taxation in modern Romania, starting from the formation of the United Principalities (1859 via the international recognition of Romania as a kingdom (1881, the formation of the National Unitary (1918 international recognition (1919 - 1921, the interwar period (1918-1939, the Second world War (1939-1945 suffered territorial losses in 1940 , the communist period (1945-1989, the post-communist period (1989-2006, will deepen in a future article pre and post EU accession in terms of fiscal and customs.

Constanta ENEA

2014-02-01

405

Spectral broadening and compression of high-intensity laser pulses in quasi-periodic systems with Kerr nonlinearity  

Energy Technology Data Exchange (ETDEWEB)

We report the results of theoretical studies and numerical simulations of optical high-power pulse compression systems based on the spectral broadening in a Kerr nonlinear medium with subsequent pulse compression in a dispersive delay line. It is shown that the effective spectral broadening requires suppressing a smallscale instability arising due to self-focusing, which is possible in quasi-periodic systems consisting of a nonlinear medium and optical relay telescopes transmitting images of the laser beam through the system. The numerical calculations have shown the possibility of broadening the spectrum, followed by 15-fold pulse compression until the instability is excited. (control of laser radiation parameters)

Vlasov, Sergei N; Koposova, E V; Yashin, V E

2012-11-30

406

A multi-wavelength study of the long-period AM Her system E2003+225  

International Nuclear Information System (INIS)

The longest period AM Her system E2003+225 was observed on 1984 July 24 with IUE, with simultaneous optical spectroscopy and photometry from La Palma. The variations of the overall continuum from 1200 to 5000 A with orbital phase allow a study of the different spectral components in the system. High-resolution optical spectra show complex line profiles containing broad and narrow components. We associate one narrow component with the heated surface of the secondary star, which has enabled us to estimate the parameters of the binary system. E2003+225 has revealed substantial changes compared with the earlier observations. (author)

1986-08-15

407

RTA beam dynamics experiments: limiting cumulative transverse instability growth in a linear periodic system  

International Nuclear Information System (INIS)

A critical issue for a Two-Beam accelerator based upon extended relativistic klystrons is controlling the cumulative dipole instability growth We describe a theoretical scheme to reduce the growth from an exponential to a more manageable linear rate, and a new experiment to test this concept. The experiment utilizes a 1-MeV, 600-Amp, 200-ns electron beam and a short beamline of periodically spaced RF dipole pillbox cavities and solenoid magnets for transport. Descriptions of the RTA injector and the planned beamline are presented, followed by theoretical studies of the beam transport and dipole mode growth

2000-06-10

408

RTA beam dynamics experiments: Limiting cumulative transverse instability growth in a linear periodic system  

International Nuclear Information System (INIS)

A critical issue for a Two-Beam accelerator based upon extended relativistic klystrons is controlling the cumulative dipole instability growth. We describe a theoretical scheme to reduce the growth from an exponential to a more manageable linear rate, and a new experiment to test this concept. The experiment utilizes a 1-MeV, 600-Amp, 200-ns electron beam and a short beamline of periodically spaced RF dipole pillbox cavities and solenoid magnets for transport. Descriptions of the RTA injector and the planned beamline are presented, followed by theoretical studies of the beam transport and dipole mode growth

2001-05-31

409

The RTA Betatron-Node Experiment Limiting Cumulative BBU Growth In A Linear Periodic System  

CERN Document Server

The successful operation of a Two-Beam accelerator based on extended relativistic klystrons hinges upon decreasing the cumulative dipole BBU growth from an exponential to a more manageable linear growth rate. We describe the theoretical scheme to achieve this, and a new experiment to test this concept. The experiment utilizes a 1-MeV, 600-Amp, 200-ns electron beam and a short beamline of periodically-spaced rf dipole-mode pillbox cavities and solenoid magnets for transport. Descriptions of the beamline are presented, followed by theoretical studies of the beam transport and dipole-mode growth.

Lidia, S M; Westenskow, G A

2000-01-01

410

The RTA betatron-node experiment: Limiting cumulative BBU growth in a linear periodic system  

International Nuclear Information System (INIS)

The successful operation of a Two-Beam accelerator based on extended relativistic klystrons hinges upon decreasing the cumulative dipole BBU growth from an exponential to a more manageable linear growth rate. The authors describe the theoretical scheme to achieve this, and a new experiment to test this concept. The experiment utilizes a 1-MeV, 600-Amp, 200-ns electron beam and a short beamline of periodically-spaced rf dipole-mode pillbox cavities and solenoid magnets for transport. Descriptions of the beamline are presented, followed by theoretical studies of the beam transport and dipole-mode growth

2000-08-21

411

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

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

2013-01-01

412

Design of a period batch control planning system for cellular manufacturing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study aimed at gaining insight into the main factors that have to be taken into account when designing a planning system for the co-ordination between cells in a cellular manufacturing system. In the last decades, the application of cellular manufacturing systems has become increasingly popular, both in production and service industries. The concept is known under various names: team based production, semi-autonomous groups, group technology, and so on. A change towards cellular manu...

Riezebos, Jan

2001-01-01

413

Sub-daily periodic radon signals in a confined radon system.  

Science.gov (United States)

Signals from radon in air enclosed in a tight canister are recorded by five gamma detectors located around the horizontal plane and along the vertical axis. At steady state conditions (diffusion input = radon decay) the primary variation is of daily radon (DR) signals with amplitudes of around 20-25%. The DR signal, with a rounded form, is characterized by periodicities of 24-, 12- and 8-h (i.e. 1, 2 & 3 CPD). Similar DR variation patterns occur in the east and west sensors whereas inverse DR patterns are recorded by the north and south sensors. Short term (ST) signals, having saw tooth form and periods of 2-3 h (frequencies in the range of 9-12 CPD) are observed at all five sensors and are superimposed on the DR signals with relative amplitudes of around 20%. They exhibit differing forms and phase at the different sensors, located at different directions around the canister. The latter is similar to the spatial manifestation of form and phase of the DR signal in such experiments, indicating a communality of the driving mechanism. At this stage a geophysical explanation cannot be presented for the ST signals. In this respect a peculiar observation is that their extraordinary occurrence coincides in time with the Tohoku Earthquake (Mw = 9.0; 11 March 2011). PMID:24704767

Steinitz, G; Piatibratova, O; Kotlarsky, P

2014-08-01

414

Formation of surface periodic microstructure at laser irradiation of the multilayer Ni/Cu/Cr system  

Energy Technology Data Exchange (ETDEWEB)

The effect of periodic pulsed laser irradiation ({lambda} = 1.06 {mu}m and power density of 0.6-0.8 x 10{sup 4} W/cm{sup 2}) on the solid-phase reaction in thin-film Ni/Cu/Cr structure (each layer of 100 nm thick) is studied by means of Auger electron spectroscopy and scanning electron microscopy. Thin-film structure is found to transform under irradiation into eutectic Cr-Ni structure with the particles of the leading Cr(Ni) phase having the radii equal to the total thickness of the film (300 nm). Eutectic colonies of these particles form the surface microstructure which consists of periodic arc-shaped bands with bars between them. The laser-induced diffusion is shown to occur under the sign-variable temperature gradient ({approx}10{sup 5} K/s), high deformation rate ({approx}20 s{sup -1}), and large dislocation flow ({rho}v{approx}10{sup 11}cm{sup -1}s{sup -1}) at low deformation degree ({approx}0.01)

Vasylyev, M.A.; Nischenko, M.M. [Institute for Metal Physics, National Academy of Sciences of Ukraine, Acad. Vernadsky Boulevard 36, 03680 Kyiv-142 (Ukraine); Tinkov, V.A. [Institute for Metal Physics, National Academy of Sciences of Ukraine, Acad. Vernadsky Boulevard 36, 03680 Kyiv-142 (Ukraine)], E-mail: sheyh@imp.kiev.ua; Sidorenko, S.I.; Voloshko, S.M. [National Technical University of Ukraine ' Kyiv Polytechnic Institute' , 37 Prospect Peremohy, 03056 Kyiv-56 (Ukraine)

2008-12-30

415

18 CFR 301.4 - Exchange Period Average System Cost determination.  

Science.gov (United States)

...of their Contract System Load and associated Exchange Load, as well as a current distribution loss analysis as described in Endnote e of Appendix 1, with their Appendix 1 filings. The load forecast for Contract System Load and Exchange Load will...

2010-04-01

416

18 CFR 301.5 - Exchange Period Average System Cost Determination.  

Science.gov (United States)

...forecast of their Contract System Load and associated Exchange Load, as well as a current distribution loss study as described in endnote e/ of Appendix 1, with their Appendix 1 listing. The load forecast for Contract System Load and Exchange Load will be...

2009-04-01

417

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

CERN Document Server

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

418

Short period dispersion management of 160 Gb/s single channel fiber system  

DEFF Research Database (Denmark)

A transmission distance of 7500 km is numerically predicted for 160 Gb/s single channel fiber systems by using realistic dispersion parameters of ± 6 ps/nm/km. System tolerance on third order dispersion and optical filtering is investigated.

Zhenbo, Xu; Peucheret, Christophe

2002-01-01

419

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

International Nuclear Information System (INIS)

Within the context of the Radioprotection program of the CEC, the RODOS project (Real-time On-line DecisiOn Support system) aims at the development of a decision support system for nuclear emergencies. RODOS involves 22 research teams, divided in 4 sub-projects: 'Meteorology and Atmospheric Dispersion, 'System Development', 'Decision Aiding Techniques'. The fourth sub-project is a Joint Study Project of the Agreement between CEC ad the CIS republics. EDF is working in the 'System Development' sub-project and namely in the 'training' group. This group aims at the creation of a specific training course for health physics managers, based on RODOS. This note reproduces the progress report of the 'Development System' project. The reporting period is: September 92 - August 93. Progress bas been made within the reporting period in the: - development of data assimilation methods incorporating both monitoring data and model predictions for obtaining consistent pictures of the environmental contamination and the source term ; - improvement and extension of the modules ATSTEP-CORA (atmospheric dispersion and deposition), EMERSIM (simulation of emergency actions), ECOAMOR (exposure pathways and dose calculation) and FRODO (simulation of relocation and agricultural countermeasures) ; - preparation of training courses using RODOS as illustrative tool ; - extension of the functions of the RODOS operating system OSY, in particular of RoGIS, its geographical information system. (author). 2 figs

420

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

International Nuclear Information System (INIS)

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

1980-01-01

 
 
 
 
421

Qualitative control of periodic solutions in piecewise affine systems; application to genetic networks  

CERN Document Server

Hybrid systems, and especially piecewise affine (PWA) systems, are often used to model gene regulatory networks. In this paper we elaborate on previous work about control problems for this class of models, using also some recent results guaranteeing the existence and uniqueness of limit cycles, based solely on a discrete abstraction of the system and its interaction structure. Our aim is to control the transition graph of the PWA system to obtain an oscillatory behaviour, which is indeed of primary functional importance in numerous biological networks; we show how it is possible to control the appearance or disappearance of a unique stable limit cycle by hybrid qualitative action on the degradation rates of the PWA system, both by static and dynamic feedback, i.e. the adequate coupling of a controlling subnetwork. This is illustrated on two classical gene network modules, having the structure of mixed feedback loops.

Farcot, Etienne

2009-01-01

422

Dynamic Scheduling of Skippable Periodic Tasks with Energy Efficiency in Weakly Hard Real-Time System  

CERN Document Server

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 while energy reduction can be obtained using lower voltage and frequency. Instead of lowering processor voltage and frequency as much as possible, energy efficient real-time scheduling adjusts voltage and frequency 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 of battery powered porta...

Baskaran, Santhi

2010-01-01

423

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

2011-04-01

424

Safety characteristics of non-lithium battery systems. Final report for period ending FY84  

Energy Technology Data Exchange (ETDEWEB)

A study was conducted to determine the safety characteristics for both primary and secondary non-lithium battery systems. Of particular interest was the behavior of these battery systems when subjected to the electrical and thermal-abuse testing procedures of NAVSEAINST 9310.1A (i.e., short circuit, forced overdischarge, and incineration). Also included are the safety/hazard characteristics associated with charging primary batteries and overcharging secondary batteries. This report also summarizes the manufacture, electrical performance, failure mechanisms, self-discharge, and applications for twenty-two primary and nineteen secondary battery systems.

Murphy, R.M.; Bis, R.F.

1984-07-01

425

Pork meat matured for different periods of time in vacuum-packaging system  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this study was to evaluate the quality of pork meat when matured. The treatments evaluated were: meat no maturated; meat matured for 3 days; meat matured for 6 days. The pH, water loss percentage, and liquid lost in thawing displayed a decreasing linear regression while the fluid lost in cooking showed an increasing linear regression. The L*, a*, b* and chroma showed an increasing linear effect while the tone displayed a decreasing linear regression. The mesophilic and psychrotrophic bacteria counts were greater for the treatments that underwent maturation. The shear force decrease linearly with the increase in the maturation period. The MFI, lipid oxidation, and sensory analyses were not affected by treatments. The maturation of the pork meat improved the color, reduced the pH and increased the tenderness. There was no change in the lipid stability of the meat, nor sensory damage.

Marina Avena Tarsitano

2014-02-01

426

Optimization of congested traffic flow in systems with a localized periodic inhomogeneity  

CERN Document Server

We study traffic flow on roads with a localized periodic inhomogeneity such as traffic signals, using a stochastic car-following model. We find that in cases of congestion, traffic flow can be optimized by controlling the inhomogeneity's frequency. By studying the wavelength dependence of the flux in stop-and-go traffic states, and exploring their stability, we are able to explain the optimization process. A general conclusion drawn from this study is, that the fundamental diagram of traffic (density flux relation) has to be generalized to include the influence of wavelength on the flux, for the stop-and-go traffic. Projecting the generalized fundamental diagram on the density-flux plane yields a 2D region, qualitatively similar to that found empirically [B. S. Kerner, Phys. Rev. Lett. {\\bf 81}, 3797 (1998)] in synchronized flow.

Tomer, E; Madar, N; Havlin, S; Tomer, Elad; Safonov, Leonid; Madar, Nilly; Havlin, Shlomo

2001-01-01

427

ARPES in strongly correlated 4f and 5f systems: Comparison to the Periodic Anderson Model  

International Nuclear Information System (INIS)

The electronic structure of both Ce and U heavy fermions appears to consist of extremely narrow, nearly temperature independent bands (i.e., no spectral weight loss or transfer with temperature). A small dispersion of the f-bands above the Kondo temperature is easily measurable so that a Kondo resonance, as defined by NCA, is not evident. Preliminary results, however, indicate that the Periodic Anderson Model captures some of the essential physics. Angle-integrated resonant photoemission results on ?-Pu indicate a narrow 5f feature at E_F, similar in width to f-states in Ce and U compounds, but differing in that cross-section behavior of the near-E_F feature suggests substantial 6D admixture

1997-09-21

428

ARPES in strongly correlated 4f and 5f systems: Comparison to the Periodic Anderson Model  

Energy Technology Data Exchange (ETDEWEB)

The electronic structure of both Ce and U heavy fermions appears to consist of extremely narrow, nearly temperature independent bands (i.e., no spectral weight loss or transfer with temperature). A small dispersion of the f-bands above the Kondo temperature is easily measurable so that a Kondo resonance, as defined by NCA, is not evident. Preliminary results, however, indicate that the Periodic Anderson Model captures some of the essential physics. Angle-integrated resonant photoemission results on {delta}-Pu indicate a narrow 5f feature at E{sub F}, similar in width to f-states in Ce and U compounds, but differing in that cross-section behavior of the near-E{sub F} feature suggests substantial 6D admixture.

Arko, A.J.; Joyce, J.J.; Cox, L.E. [and others

1997-12-01

429

Transfer of elliptical emittance of a charged particle beam through a periodical optical system  

International Nuclear Information System (INIS)

The matrix formalism was used to search for the relation between the ?, ? and ? parameters of the magnetic module and the emittance parameters of a beam of charged particles transferred through a magneto-optical system. (author). 1 fig., 3 refs

1989-01-01

430

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

2009-12-01

431

The HD 192263 system: planetary orbital period and stellar variability disentangled  

Digital Repository Infrastructure Vision for European Research (DRIVER)

As part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS), 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...

Dragomir, Diana; Kane, Stephen R.; Henry, Gregory W.; Ciardi, David R.; Fischer, Debra A.; Howard, Andrew W.; Jensen, Eric L. N.; Laughlin, Gregory; Mahadevan, Suvrath; Matthews, Jaymie M.; Pilyavsky, Genady; Von Braun, Kaspar; Wang, Sharon X.; Wright, Jason T.

2012-01-01

432

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.