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1

Some comments on the views of Niaz, Rodriguez and Brito on Mendeleev's periodic system  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in english Many articles have been written about the value of incorporating an understanding of history and philosophy of science into science education and this has included the teaching of chemistry. Given the immense role that the periodic table plays in chemistry it is important to be clear about a histori [...] cal and philosophical perspective on the periodic table and its possible ramifications for the way in which chemistry is presented. The article presents a critique of a paper by Niaz, Rodriguez and Brito who have addressed the relevance of historical and philosophical aspects of the periodic table in an article in which they have claimed that Mendeleev's periodic table should be regarded as a theory. In addition they have claimed that Mendeleev was a supporter of the atomic theory and have addressed some general philosophical questions concerning inductivism and the role of prediction and accommodation in the acceptance of scientific discoveries.

Eric, Scerri.

2

The Different Periodic Tables of Dmitrii Mendeleev  

Science.gov (United States)

Between 1869 and 1905 the Russian chemist Dmitrii Mendeleev published several tables with different arrangements of the chemical elements. Four of these are compared with periodic tables by Russian scientists from 1934 and 1969. The difficulties caused by the lanthanoid elements are clearly seen in the table of 1905, which satisfactorily includes…

Laing, Michael

2008-01-01

3

Novelty, coherence, and Mendeleev's periodic table.  

Science.gov (United States)

Predictivism is the view that successful predictions of "novel" evidence carry more confirmational weight than accommodations of already known evidence. Novelty, in this context, has traditionally been conceived of as temporal novelty. However temporal predictivism has been criticized for lacking a rationale: why should the time order of theory and evidence matter? Instead, it has been proposed, novelty should be construed in terms of use-novelty, according to which evidence is novel if it was not used in the construction of a theory. Only if evidence is use-novel can it fully support the theory entailing it. As I point out in this paper, the writings of the most influential proponent of use-novelty contain a weaker and a stronger version of use-novelty. However both versions, I argue, are problematic. With regard to the appraisal of Mendeleev' periodic table, the most contentious historical case in the predictivism debate, I argue that temporal predictivism is indeed supported, although in ways not previously appreciated. On the basis of this case, I argue for a form of so-called symptomatic predictivism according to which temporally novel predictions carry more confirmational weight only insofar as they reveal the theory's presumed coherence of facts as real. PMID:24984451

Schindler, Samuel

2014-03-01

4

Interaction properties of ytterbium with elements of Mendeleev periodic table  

International Nuclear Information System (INIS)

This article presents the new data on ytterbium interaction with elements of Mendeleev periodic table. The state diagrams of ytterbium with magnesium, calcium, strontium, and barium are constructed. The state diagrams of ytterbium with Cu, Ag, Au, Zn, Cd, Hg, B,Al, Ga, In, Tl are considered.

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Energy capacity of elements in periodic table of D.I.Mendeleev  

International Nuclear Information System (INIS)

A great difference in the intensity of heat constent variation from one element to another is detected. The notion of energy capacity of elements is introduced. It is an energy characteristic, determining arrangement of elements in the D.I.Mendeleev Periodic system. The value of energy capacity depends on external conditions (temperature, pressure, etc.). Lanthanides and actinides are systematized on the basis of their energy capacity, atomic mass and melting points. It is shown, that energy capcity, determining element location in thePeriodic system, characterizes the intensity of their energy state variation. Energy state of monocomponent systems with any mass number determines their physicomechanical properties

6

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

7

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 elem...

Kibler, M. R.

2007-01-01

8

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

Energy Technology Data Exchange (ETDEWEB)

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

Kibler, Maurice R. [Universite de Lyon, Institut de Physique Nucleaire, Universite Lyon 1 and CNRS/IN2P3, 43 Bd du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France)

2006-11-15

9

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

International Nuclear Information System (INIS)

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

10

Evidence for Energy Regularity in the Mendeleev Periodic Table  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We show that the dependence of the total energy of the atoms on their atomic number follows a q-exponential (function proposed by C. Tsallis), for almost 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.; Zambrano, Liliana S.

2008-01-01

11

Social background of the discovery and the reception of the periodic law of the elements: recognizing the contributions of Dmitri Ivanovich Mendeleev and Julius Lothar Meyer.  

Science.gov (United States)

The favorable and relatively rapid reception of Mendeleev's periodic table of the elements can be attributed, in part at least, to his social connections. These connections were evident in the recently organized Russian Chemical Society. In addition, Mendeleev enjoyed the support of the editorial board of the journal of the German Chemical Society. PMID:12796115

Kaji, Masanori

2003-05-01

12

Investigating Patterns: An introduction to Mendeleev, periodicity, and the Periodic Table  

Science.gov (United States)

This activity is a puzzle where students organize samples and look for patterns in order to predict properties of missing puzzle pieces. The students then relate their experience to the historical development of the Periodic Table and the ways that the Periodic Table can be used to predict the properties of the elements.

Jennifer Hogan

13

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)

14

Superconductivity, antiferromagnetism and ferromagnetism in periodic table of D.I. Mendeleev  

International Nuclear Information System (INIS)

Definite regularity in the distribution of ferromagnetic, antiferromagnetic and superconducting elements is observed in the periodic table starting with the 4th period. Elements with superconductivity, by which d-shells start to fill up, are at the beginning of each period; then follow antiferromagnetics and ferromagnetics (in 4th period and lanthanides), or elements without any of the three listed order types (5th period and 6th period), in which the d (f)-shells continue to fill up almost exceedingly; then again appear superconductors by filling the p-shell up to the number is equal to 4. We calculated the radii of the external d (f)- and p-orbitals and the nearest to them orbitals with the Slater method. These trends were explained by distinction of degree of division of the external d (f)- or p-orbitals of the neighboring atoms in the crystal. Largest division occurs in ferromagnetics. In antiferromagnetics it is smaller than in ferromagnetics. It is demonstrated that in the superconducting crystals the external dor p-shells approach the nucleus of neighboring atoms are much closely those for ferromagnetic or antiferromagnetic crystals. Furthermore the external d- or p-shells of some elements in the 5th and 6th periods approach the deeper shells of neighboring atoms. Hence the electron in this shell is situated in neighboring atoms in a different electric field from its own. This fact is open to speculation that the separation of spin and charge in electron, dispotion of spin and charge in electron, disposed on the external d- or p-orbitals, is quite possible. The charges without spin become bosons. Spins that have the magnetic moments are ordered antiparallel in pairs. Magnetic field transfers this pair in a parallel state and a magnetic flux component along of magnetic field from the pair is equal to one fluxon (the quant of the magnetic flux).

15

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

International Nuclear Information System (INIS)

The great influence of the Berthelot's ideas about the non existence of atoms froze the teaching of chemistry in France for quite a long time. It is only after the Second World War that the study of the atom structure appeared in school curricula. The Mendeleev periodic system that sets the relationship between chemical properties and atom structure entered the curriculum even later in 1978. The article shows that the authors of most school manuals had anticipated the change, for in 1966 all the chemistry manuals of the 6. form had a chapter dedicated to the Mendeleev table while the issue was not yet on the syllabus. (A.C.)

16

The slow penetration of the Mendeleev Table in the French school curricula; La lente introduction de la classification periodique dans les programmes d'enseignement en France  

Energy Technology Data Exchange (ETDEWEB)

The great influence of the Berthelot's ideas about the non existence of atoms froze the teaching of chemistry in France for quite a long time. It is only after the Second World War that the study of the atom structure appeared in school curricula. The Mendeleev periodic system that sets the relationship between chemical properties and atom structure entered the curriculum even later in 1978. The article shows that the authors of most school manuals had anticipated the change, for in 1966 all the chemistry manuals of the 6. form had a chapter dedicated to the Mendeleev table while the issue was not yet on the syllabus. (A.C.)

Vigouroux, C.H. [42300 Roanne (France)

2012-02-15

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XVII Mendeleev congress on general and applied chemistry. Summary of reports. Volume 4. Russian-French symposium Supramolecular systems in chemistry and biology. Chemical education. Russian-American symposium on chemical education. Biomolecular chemistry and biotechnology. Petrochemistry and catalysis. Symposium devoted to centenary from discovery of chromatography by M.S. Tsvet  

International Nuclear Information System (INIS)

Reports of the XVII Mendeleev congress on general and applied chemistry, volume 4 (Kazan', 21 - 26 September, 2003) are presented. Current status and prospects of chemical science, biomolecular chemistry and biotechnology, petrochemistry and catalysis, chemical education, as well as some ecological problems are treated in the collection. Materials of the Russian-French symposium: Supramolecular systems in chemistry and biology, Russian-American symposium on chemical education as well as symposium devoted to the 100 anniversary from the discovery of chromatography by Russian scientist M.S. Tsvet are included in the volume. Prospects for the development of chromatography and applications of this method are discussed

18

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

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The Periodic Table in Croatia  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 enthusiasti...

Raos, N.

2011-01-01

20

Superheavy elements in D I Mendeleev's Periodic Table  

International Nuclear Information System (INIS)

The results on the synthesis of new superheavy elements, synthesized in complete fusion reactions of 48Ca ions with actinide targets, are summarized and analyzed. The perspectives for the synthesis of element 117, as well as of elements with Z?118 are also considered.

 
 
 
 
21

Availability of periodically tested systems  

International Nuclear Information System (INIS)

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

22

Soliton Management in Periodic Systems  

CERN Document Server

During the past ten years, there has been intensive development in theoretical and experimental research of solitons in periodic media. This book provides a unique and informative account of the state-of-the-art in the field. The volume opens with a review of the existence of robust solitary pulses in systems built as a periodic concatenation of very different elements. Among the most famous examples of this type of systems are the dispersion management in fiber-optic telecommunication links, and (more recently) photonic crystals. A number of other systems belonging to the same broad class of spatially periodic strongly inhomogeneous media (such as the split-step and tandem models) have recently been identified in nonlinear optics, and transmission of solitary pulses in them was investigated in detail. Similar soliton dynamics occurs in temporal-domain counterparts of such systems, where they are subject to strong time-periodic modulation (for instance, the Feshbach-resonance management in Bose-Einstein conde...

Malomed, Boris A

2006-01-01

23

Half-Period Excitations in Continuum Periodic Systems  

CERN Document Server

We investigate the generation of half-period states in continuum periodic systems. As a prototypical example, we use a trapped Bose-Einstein condensate confined in a periodic optical-lattice potential. We show that when the potential is turned on sufficiently nonadiabatically, the system tries to reach its new ground state by transiting through states with periodicity half that of the lattice. The particularly intriguing characteristic of such states is that they cannot be captured by discrete systems such as the discrete nonlinear Schr{\\"o}dinger equation. We illustrate the origin of these states mathematically by treating them as superharmonic resonances of a parametrically forced Duffing oscillator and discuss their transient nature and potential observability.

Nistazakis, H E; Kevrekidis, P G; Frantzeskakis, D J; Nicolin, A; Chin, J K; Porter, Mason A.

2005-01-01

24

Origin of the Periodic Table  

Science.gov (United States)

This site provides a description of the development of the periodic table by Dmitri Mendeleev based on weight and common physical and chemical properties. An overview of the tableâs organization scheme is contained along with links to information about the Schrödinger and Rutherford atomic models. More information about Mendeleevâs methods and the chemistry of his time are also provided.

2006-12-25

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

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

28

Design of periodic beam-transport systems  

International Nuclear Information System (INIS)

Periodic beam-transport systems have several advantages including insensitivity to errors, minimum magnet apertures, and use of standardized components. A simple procedure is given for the design of modules, with and without bending magnets, that have the same matched beam properties. These modules can be combined in certain ways to produce systems that are achromatic and require a minimum number of matching elements

29

Localized States in Periodically Forced Systems  

Science.gov (United States)

The theory of stationary spatially localized patterns in dissipative systems driven by time-independent forcing is well developed. With time-periodic forcing, related but time-dependent structures may result. These may consist of breathing localized patterns, or states that grow for part of the cycle via nucleation of new wavelengths of the pattern followed by wavelength annihilation during the remainder of the cycle. These two competing processes lead to a complex phase diagram whose structure is a consequence of a series of resonances between the nucleation time and the forcing period. The resulting diagram is computed for the periodically forced quadratic-cubic Swift-Hohenberg equation, and its details are interpreted in terms of the properties of the depinning transition for the fronts bounding the localized state on either side. The results are expected to shed light on localized states in a large variety of periodically driven systems.

Gandhi, Punit; Knobloch, Edgar; Beaume, Cédric

2015-01-01

30

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

31

On periodic solutions of superquadratic Hamiltonian systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Guihua Fei

2002-01-01

32

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)

33

On systems of periodic differential equations  

International Nuclear Information System (INIS)

For many problems in theoretical physics it is necessary to know as much as possible about the solutions of linear differential equations with periodic coefficients. Such systems appear for instance in the theory of parametric oscillations, in connection with the motion of particles in periodic fields etc. The most important task in this context is the determination of the characteristic exponents, which decide about the stability or instability of the solutions. In practice the system in question is frequently not of the most general form, but has certain symmetry properties. In this case one may obtain statements about the characteristic exponents directly from simple symmetry considerations. The authors derive some theorems of this sort, which have been found to be useful in applications. (Auth.)

34

Effective imaging systems based on periodic lattices  

International Nuclear Information System (INIS)

A crucial question in imaging problems from diffracted wavefields is the evaluation of the information content of data and the related reconstruction performance in terms of spatial resolution. It is well-known that full-view tomographic reconstructions are characterized by resolution limits of the order of one half propagated wavelength. These limits are further deteriorated when a truncated measurement domain is exploited for the imaging. In this Letter, we show that when the imaging system comprises a periodic layer located between a linear array of probes and the investigated domain, the resolution limits are substantially improved compared to the case of a homogenous scenario. This intriguing result is a consequence of the multiscattering effects arising from the periodicity of the structure. The study provides physical insight supported by mathematical arguments paving the way to the development of effective imaging systems requiring few radiating elements

35

Effective imaging systems based on periodic lattices  

Energy Technology Data Exchange (ETDEWEB)

A crucial question in imaging problems from diffracted wavefields is the evaluation of the information content of data and the related reconstruction performance in terms of spatial resolution. It is well-known that full-view tomographic reconstructions are characterized by resolution limits of the order of one half propagated wavelength. These limits are further deteriorated when a truncated measurement domain is exploited for the imaging. In this Letter, we show that when the imaging system comprises a periodic layer located between a linear array of probes and the investigated domain, the resolution limits are substantially improved compared to the case of a homogenous scenario. This intriguing result is a consequence of the multiscattering effects arising from the periodicity of the structure. The study provides physical insight supported by mathematical arguments paving the way to the development of effective imaging systems requiring few radiating elements.

Gennarelli, Gianluca, E-mail: gennarelli.g@irea.cnr.it; Soldovieri, Francesco [Institute for Electromagnetic Sensing of the Environment, National Research Council of Italy, Via Diocleziano 328, 80124 Napoli (Italy); Persico, Raffaele [Institute for Archaeological and Monumental Heritage, National Research Council of Italy, Via Monteroni, Campus Universitario, 73100 Lecce (Italy)

2014-05-12

36

Periodic Solutions for Highly Nonlinear Oscillation Systems  

DEFF Research Database (Denmark)

In this paper, Frequency-Amplitude Formulation is used to analyze the periodic behavior of tapered beam as well as two complex nonlinear systems. Many engineering structures, such as offshore foundations, oil platform supports, tower structures and moving arms, are modeled as tapered beams. The results obtained are compared with Variational Iteration Method (VIM) and other analytical methods as well as time marching solution. The results given show the effectiveness and accuracy of the proposed techniques.

Ghadimi, M; Barari, Amin

2012-01-01

37

Close binary systems of short period  

International Nuclear Information System (INIS)

Information on 406 close binary systems with periods less than 1.5 days for which the primary is of known spectral type, is assembled from recent sources. The organization of the presentation depends on a light curve descriptor which takes the values EA1, EA2, EA3, EB, EW and E 11. Within these groups the distribution in the spectral type (s):period (P) plane is examined. An additional distribution of this kind is presented for 311 EA2 candidate stars (evolved Algols), with periods of up to 15 days. Recent empirical information on Main Sequence stars is presented for comparison, and the condition that a Main Sequence component of a binary system be in 'contact' with its surrounding Roche lobe provides an interesting discriminant in relation to the (s:P) distributions of the different light curve groups. Certain anomalous cases come to light. Concerning the EW (W UMa) group, detailed investigation of a particular case reveals the extent of parameter indeterminacy. A compelling case for 'contact' can only be found among the accumulation which occurs at later spectral type. A recommendation is made for a simple but more quantitative means of defining light curve type. Such a parameter could be of considerable significance in relation to statistical tests of binary evolution theory. (Auth.)

38

Collapse period of degrading SDOF systems  

Science.gov (United States)

Seismic demand estimation for a structure is a critical issue for seismic performance assessment so that the potential damage can be estimated realistically. Many researchers proposed simplified methods to estimate the demand of a structure under strong ground motions. However, most of them did not consider degradation and collapse potential of the structures. Even some of theme considered the degradation effect, stiffness and strength degradation effects were considered separately without collapse potential caused by dynamic instability. In this study, collapse potential of SDOF systems caused by dynamic instability with stiffness and strength degradation has been investigated. Nonlinear time history analyses were performed, using an energy-based, strength and stiffness degraded hysteretic model that considers the collapse potential, with 160 earthquake acceleration time histories. An equation was proposed for the estimation of collapse period of SDOF systems as a function of certain strength reduction factor, ductility level and post-capping stiffness ratio. Finally, effects of parameters of the considered hysteretic model and local site conditions on the collapse period were investigated.

Borekci, M.; Kirçil, M. S.; Ekiz, I.

2014-12-01

39

Occurrence of multiple period-doubling bifurcation route to chaos in periodically pulsed chaotic dynamical systems  

International Nuclear Information System (INIS)

We consider the effect of discrete-time signal or periodically pulsed forcing on chaotic dynamical systems and show that the systems can undergo novel multiple period-doubling bifurcations prior to the onset of chaos, followed by a rich variety of dynamical phenomena including enlarged periodic windows, attractor crises, distinctly modified bifurcation structures and so on. Under certain circumstances, these systems also admit transcritical bifurcations preceding the onset of multiple period-doubling bifurcations. These properties are demonstrated for the case of Duffing oscillator. We also explain the occurrence of multiple period-doubling by means of a periodically forced logistic map

40

Nucleation in periodically driven electrochemical systems  

Science.gov (United States)

We calculate both the exponent and the prefactor in the nucleation rate of a periodically driven system. Nucleation dynamics is described by the Fokker-Planck equation for the probability distribution of the nuclei over their size. This distribution is found using the concept of the most probable (optimal) nucleation path. The results apply in a broad range of driving force amplitudes, from weak to moderately strong forces where the nucleation rate is changed exponentially strongly, and also in the broad range of the driving frequencies, from low-frequency driving, where the system follows the force adiabatically, to high-frequency nonadiabatic driving. For strong driving forces, the time dependence of the nucleation rate changes from strongly nonsinusoidal to a weak with the increasing frequency of driving. The response of the nucleation rate to the driving force is described in terms of logarithmic susceptibility (LS), which can be obtained from the optimal nucleation path in the absence of the driving. LS is a smooth function of frequency, and therefore even a driving force with comparatively high frequency can change the modulation rate exponentially strongly. LS and the Faraday current are calculated for simple models of electrochemical systems, where the ac driving is produced by modulation of the electrode potential. We also suggest how to find LS from measurements of the average nucleation rate.

Smelyanskiy, V. N.; Dykman, M. I.; Rabitz, H.; Vugmeister, B. E.; Bernasek, S. L.; Bocarsly, A. B.

1999-06-01

 
 
 
 
41

Periodic solutions of a forced system with hysteresis.  

Science.gov (United States)

Hysteresis damping arising in an oscillatory system due to the phenomenon of slip damping analyzed by Goodman and Klumpp (1956) is considered. An idealized physical model is proposed, and the existence of certain periodic motions is investigated in a system with small forcing which are near the largest periodic motion in a corresponding unforced system. Periodic solutions of the forced system are obtained.-

Drew, J. H.

1972-01-01

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 and quasi-periodicity for super-integrable hamiltonian systems  

International Nuclear Information System (INIS)

Classical trajectories are calculated for two Hamiltonian systems with ring shaped potentials. Both systems are super-integrable, but not maximally super-integrable, having four globally defined single-valued integrals of motion each. All finite trajectories are quasi-periodical; they become truly periodical if a commensurability condition is imposed on an angular momentum component

44

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

Science.gov (United States)

Although several chemical elements were not known by end of the 19th century, Mendeleev came up with an astonishing achievement, the periodic table of elements. He was not only able to predict the existence of (then) new elements, but also to provide accurate estimates of their chemical and physical properties. This is a profound example of the…

Lemes, Mauricio R.; Dal Pino, Arnaldo

2011-01-01

45

Poincare index and periodic solutions of perturbed autonomous systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The basic tool of classical results by Malkin and Melnikov on bifurcation of periodic solutions from nondegenerate cycles of autonomous systems with periodic perturbations is an implicit function theorem. In this paper the Poincare index is used to avoid the requirement of nondegeneracity for the unperturbed cycles and to provide additional geometrical properties of periodic solutions of the perturbed system.

Makarenkov, Oleg

2007-01-01

46

On the periodic Schr\\"odinger-Boussinesq System  

CERN Document Server

We study the local and global well-posedness of the periodic boundary value problem for the nonlinear Schr\\"odinger-Boussinesq system. The existence of periodic pulses as well as the stability of such solutions are also considered.

Farah, Luiz Gustavo

2009-01-01

47

Existence of periodic solutions of impulsive differential systems  

Directory of Open Access Journals (Sweden)

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

L. H. Erbe

1991-01-01

48

On the prescribed-period problem for autonomous Hamiltonian systems  

Directory of Open Access Journals (Sweden)

Full Text Available systems are considered. Lower bounds for the number of periodic solutions with a prescribed minimal period are obtained. These bounds are expressed in terms of the numbers of frequencies corresponding to the critical points of the Hamiltonian. Results are based on a global analysis of families of periodic solutions emanating from these points.

A. A. Zevin

1998-02-01

49

Manifold structures of unstable periodic orbits and the appearance of periodic windows in chaotic systems  

Science.gov (United States)

Manifold structures of the Lorenz system, the Hénon map, and the Kuramoto-Sivashinsky system are investigated in terms of unstable periodic orbits embedded in the attractors. Especially, changes of manifold structures are focused on when some parameters are varied. The angle between a stable manifold and an unstable manifold (manifold angle) at every sample point along an unstable periodic orbit is measured using the covariant Lyapunov vectors. It is found that the angle characterizes the parameter at which the periodic window corresponding to the unstable periodic orbit finishes, that is, a saddle-node bifurcation point. In particular, when the minimum value of the manifold angle along an unstable periodic orbit at a parameter is small (large), the corresponding periodic window exists near (away from) the parameter. It is concluded that the window sequence in a parameter space can be predicted from the manifold angles of unstable periodic orbits at some parameter. The fact is important because the local information in a parameter space characterizes the global information in it. This approach helps us find periodic windows including very small ones.

Kobayashi, Miki U.; Saiki, Yoshitaka

2014-02-01

50

Periodic Behaviors in Constrained Multi-agent Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, we provide two discrete-time multi-agent models which generate periodic behaviors. The first one is a multi-agent system of identical double integrators with input saturation constraints, while the other one is a multi-agent system of identical neutrally stable system with input saturation constraints. In each case, we show that if the feedback gain parameters of the local controller satisfy a certain condition, the multi-agent system exhibits a periodic solut...

Yang, Tao; Meng, Ziyang; Dimarogonas, Dimos V.; Johansson, Karl H.

2014-01-01

51

Periodic integrable systems with delta-potentials  

CERN Document Server

In this paper we study root system generalizations of the quantum Bose-gas on the circle with pair-wise delta function interactions. The underlying symmetry structures are shown to be governed by the associated graded of Cherednik's (suitably filtered) degenerate double affine Hecke algebra, acting by Dunkl-type differential-reflection operators. We use Gutkin's generalization of the equivalence between the impenetrable Bose-gas and the free Fermi-gas to derive the Bethe ansatz equations and the Bethe ansatz eigenfunctions.

Emsiz, E; Stokman, J V; Emsiz, Erdal; Opdam, Eric M.; Stokman, Jasper V.

2005-01-01

52

Asymptotic stability on slow time scales from periodic systems  

International Nuclear Information System (INIS)

Asymptotic stability for a periodic system of ordinary differential equations with a small parameter is shown to follow from the stability of the corresponding iterated-average system. Applications are made to biological systems experiencing varying seasonal factors, to large scale dynamical systems that are principally irrotational and to nuclear reactor dynamics. 7 refs

53

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)

54

Periodic solutions of nonautonomous differential systems modeling obesity population  

International Nuclear Information System (INIS)

In this paper we study the periodic behaviour of the solutions of a nonautonomous model for obesity population. The mathematical model represented by a nonautonomous system of nonlinear ordinary differential equations is used to model the dynamics of obese populations. Numerical simulations suggest periodic behaviour of subpopulations solutions. Sufficient conditions which guarantee the existence of a periodic positive solution are obtained using a continuation theorem based on coincidence degree theory.

55

The periodic system of chemical elements: old and new developments  

International Nuclear Information System (INIS)

Some historical facts about the construction of a periodic system of chemical elements are reviewed. The Madelung rule is used to generate an unusual format for the periodic table. Following the work of Byakov, Kulakov, Rumer and Fet, such a format is further refined on the basis of a chain of groups starting with SU(2)xS0(4.2)

56

Periodicity of a class of nonlinear fuzzy systems with delays  

International Nuclear Information System (INIS)

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.

57

Nontrivial periodic solutions of asymptotically linear Hamiltonian systems  

Directory of Open Access Journals (Sweden)

Full Text Available We study the existence of periodic solutions for some asymptotically linear Hamiltonian systems. By using the Saddle Point Theorem and Conley index theory, we obtain new results under asymptotically linear conditions.

Guihua Fei

2001-11-01

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

Gastrointestinal system obstructuions in neonatal period-I  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The suspect of gasrointestinal system obstructions rises in the prenatal period and confirmation and diagnosis are made postnatally. Thorough questioning of gestational period of a pregnant mother gives some clues in terms of gastrointestinal system obstructions. Anamnesis indicating the presence of a congenital defect in the family or relatives would lead to more careful examination of the child. Polyhydramniosis is an indication requiring special attention almost everytime. Five to ten perc...

Ergun Erdo?an

2010-01-01

60

Stabilization with finite dimensional controllers for a periodic parabolic system under perturbations in the system conductivity  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This work studies the stabilization for a periodic parabolic system under perturbations in the system conductivity. A perturbed system does not have any periodic solution in general. However, we will prove that the perturbed system can always be pulled back to a periodic system after imposing a control from a fixed finite dimensional subspace.

Lei, Ling

2009-01-01

 
 
 
 
61

Suppression of period-doubling and nonlinear parametric effects in periodically perturbed systems  

International Nuclear Information System (INIS)

We consider the effect on a generic period-doubling bifurcation of a periodic perturbation, whose frequency ?1 is near the period-doubled frequency ?0/2. The perturbation is shown to always suppress the bifurcation, shifting the bifurcation point and stabilizing the behavior at the original bifurcation point. We derive an equation characterizing the response of the system to the perturbation, analysis of which reveals many interesting features of the perturbed bifurcation, including (1) the scaling law relating the shift of the bifurcation point and the amplitude of the perturbation, (2) the characteristics of the system's response as a function of bifurcation parameter, (3) parametric amplification of the perturbation signal including nonlinear effects such as gain saturation and a discontinuity in the response at a critical perturbation amplitude, (4) the effect of the detuning (?1-?0/2) on the bifurcation, and (5) the emergence of a closely spaced set of peaks in the response spectrum. An important application is the use of period-doubling systems as small-signal amplifiers, e.g., the superconducting Josephson parametric amplifier

62

Periodic orbits for perturbations of piecewise linear systems  

Science.gov (United States)

We consider the existence of periodic orbits in a class of three-dimensional piecewise linear systems. Firstly, we describe the dynamical behavior of a non-generic piecewise linear system which has two equilibria and one two-dimensional invariant manifold foliated by periodic orbits. The aim of this work is to study the periodic orbits of the continuum that persist under a piecewise linear perturbation of the system. In order to analyze this situation, we build a real function of real variable whose zeros are related to the limit cycles that remain after the perturbation. By using this function, we state some results of existence and stability of limit cycles in the perturbed system, as well as results of bifurcations of limit cycles. The techniques presented are similar to the Melnikov theory for smooth systems and the method of averaging.

Carmona, Victoriano; Fernández-García, Soledad; Freire, Emilio

63

Optimal periodic orbits of continuous time chaotic systems  

International Nuclear Information System (INIS)

In previous work [B. R. Hunt and E. Ott, Phys. Rev. Lett. 76, 2254 (1996); Phys. Rev. E 54, 328, (1996)], based on numerical experiments and analysis, it was conjectured that the optimal orbit selected from all possible orbits on a chaotic attractor is ''typically'' a periodic orbit of low period. By an optimal orbit we mean the orbit that yields the largest value of a time average of a given smooth ''performance'' function of the system state. Thus optimality is defined with respect to the given performance function. (The study of optimal orbits is of interest in at least three contexts: controlling chaos, embedding of low-dimensional attractors of high-dimensional dynamical systems in low-dimensional measurement spaces, and bubbling bifurcations of synchronized chaotic systems.) Here we extend this previous work. In particular, the previous work was for discrete time dynamical systems, and here we shall consider continuous time systems (flows). An essential difference for flows is that chaotic attractors can have embedded within them, not only unstable periodic orbits, but also unstable steady states, and we find that optimality can often occur on steady states. We also shed further light on the sense in which optimality is ''typically'' achieved at low period. In particular, we find that, as a system parameter is tuned to be closer to a crisis of the chaotic attractor, optimality may occur at higher period. (c) 2000 The American Physical Societyrican Physical Society

64

Pseudo analytical solution to time periodic stiffness systems  

International Nuclear Information System (INIS)

An analytical form of state transition matrix for a system of equations with time periodic stiffness is derived in order to solve the free response and also allow for the determination of system stability and bifurcation. A pseudo-closed form complete solution for parametrically excited systems subjected to inhomogeneous generalized forcing is developed, based on the Fourier expansion of periodic matrices and the substitution of matrix exponential terms via Lagrange—Sylvester theorem. A Mathieu type of equation with large amplitude is presented to demonstrate the method of formulating state transition matrix and Floquet multipliers. A two-degree-of-freedom system with irregular time periodic stiffness characterized by spiral bevel gear mesh vibration is presented to find forced response in stability and instability. The obtained results are presented and discussed. (general)

65

The distribution of period ratios in Kepler planetary systems  

Science.gov (United States)

Kepler's multi-planet systems are a valuable tool to understand the architectures and dynamics of the inner parts of planetary systems. I present an analysis of the distribution of orbital period ratios from candidate systems identified in the Quarter 8 catalog (Burke et al. 2014). This distribution is corrected for the effects of geometric transit probabilities and the completeness of the data reduction pipeline. We find that the distribution of period ratios falls as a power law with exponent -1.26 ± 0.05. We also identify a new, statistically significant feature near a period ratio of 2.2. These observations may provide insights into the formation and evolution of these systems.

Steffen, Jason H.; Hwang, Jason A.

2015-01-01

66

Periodic solutions of second-order nonautonomous dynamical systems  

Directory of Open Access Journals (Sweden)

Full Text Available We study the existence of periodic solutions for second-order nonautonomous dynamical systems. We give four sets of hypotheses which guarantee the existence of solutions. We were able to weaken the hypotheses considerably from those used previously for such systems. We employ a new saddle point theorem using linking methods.

Martin Schechter

2006-08-01

67

Periodic solutions of second-order nonautonomous dynamical systems  

Directory of Open Access Journals (Sweden)

Full Text Available We study the existence of periodic solutions for second-order nonautonomous dynamical systems. We give four sets of hypotheses which guarantee the existence of solutions. We were able to weaken the hypotheses considerably from those used previously for such systems. We employ a new saddle point theorem using linking methods.

Schechter Martin

2006-01-01

68

Periodic solutions and flip bifurcation in a linear impulsive system  

International Nuclear Information System (INIS)

In this paper, the dynamical behaviour of a linear impulsive system is discussed both theoretically and numerically. The existence and the stability of period-one solution are discussed by using a discrete map. The conditions of existence for flip bifurcation are derived by using the centre manifold theorem and bifurcation theorem. The bifurcation analysis shows that chaotic solutions appear via a cascade of period-doubling in some interval of parameters. Moreover, the periodic solutions, the bifurcation diagram, and the chaotic attractor, which show their consistence with the theoretical analyses, are given in an example. (general)

69

Classification of homoclinic tangencies for periodically perturbed systems  

International Nuclear Information System (INIS)

Classification of homoclinic tangencies for periodically perturbed systems is discussed. A relationship between the order of Melnikov function's zeros and the harmonic components of a dynamical system is derived. By applying the singularity theory to the Melnikov function, possible types of homoclinic tangencies are studied for realization of the classification. In addition, certain multi-harmonically perturbed systems are investigated, showing the corresponding homoclinic bifurcation with their bifurcation diagrams

70

Long period seismic ground motions for isolation systems  

International Nuclear Information System (INIS)

In this paper numerical simulations of long period strong ground motions are calculated based on theoretical seismological models of the seismic source and wave propagation. The method includes both near-field and far-field terms and surface waves as well as body waves which allows valid simulations at both short and large distances. Long period ground motions for magnitude 6.75 and magnitude 8.0 events are computed at distances of 3 to 30 km. The resulting response spectral displacements are compared to the SEAOC 1990 spectrum for base-isolated system. At a period of 2 seconds, the SEAOC spectrum is close to the spectrum for a magnitude 8.0 earthquake. However, at a period of 5 seconds, the SEAOC spectrum is much larger than the simulated notions even for a magnitude 8 event

71

Electrostatics of solvated systems in periodic boundary conditions  

CERN Document Server

Continuum solvation methods can provide an accurate and inexpensive embedding of quantum simulations in liquid or complex dielectric environments. Notwithstanding a long history and manifold applications to isolated systems in open boundary conditions, their extension to materials simulations --- typically entailing periodic-boundary conditions --- is very recent, and special care is needed to address correctly the electrostatic terms. We discuss here how periodic-boundary corrections developed for systems in vacuum should be modified to take into account solvent effects, using as a general framework the self-consistent continuum solvation model developed within plane-wave density-functional theory [O. Andreussi et al. J. Chem. Phys. 136, 064102 (2012)]. A comprehensive discussion of real-space and reciprocal-space corrective approaches is presented, together with an assessment of their ability to remove electrostatic interactions between periodic replicas. Numerical results for zero-dimensional and two-dimen...

Andreussi, Oliviero

2014-01-01

72

Periodic inspection for safety of CANDU heat transport piping systems  

International Nuclear Information System (INIS)

Periodic inspection of heat transport and emergency core cooling piping systems is intended to maintain an adequate level of safety throughout the life of the plant, and to protect plant personnel and the public from the consequences of a failure and release of fission products. This report outlines a rational approach to the periodic inspection based on a fully probabilistic model. It demonstrates the methodology based on theoretical treatment and experimental data whereby the strength of a pressurized pipe or vessel containing a defect could be evaluated. It also shows how the extension of the defect at various lifetimes could be predicted. These relationships are prerequisite for the probabilistic formulation and analysis for the periodic inspection of piping systems

73

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

74

Multiple population-period transient spectroscopy (MUPPETS) in excitonic systems.  

Science.gov (United States)

Time-resolved experiments with more than one period of incoherent time evolution are becoming increasingly accessible. When applied to a two-level system, these experiments separate homogeneous and heterogeneous contributions to kinetic dispersion, i.e., to nonexponential relaxation. Here, the theory of two-dimensional (2D) multiple population-period transient spectroscopy (MUPPETS) is extended to multilevel, excitonic systems. A nonorthogonal basis set is introduced to simplify pathway calculations in multilevel systems. Because the exciton and biexciton signals have different signs, 2D MUPPETS cleanly separates the exciton and biexciton decays. In addition to separating homogeneous and heterogeneous dispersion of the exciton, correlations between the exciton and biexciton decays are measurable. Such correlations indicate shared features in the two relaxation mechanisms. Examples are calculated as both 2D time decays and as 2D rate spectra. The effect of solvent heating (i.e., thermal gratings) is also calculated in multidimensional experiments on multilevel systems. PMID:23343269

Wu, Haorui; Berg, Mark A

2013-01-21

75

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)

76

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

77

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

78

Periodic solutions for some second order Hamiltonian systems  

International Nuclear Information System (INIS)

We use the saddle point theorem of Benci–Rabinowitz to study the existence of periodic solutions with a fixed energy for second order Hamiltonian conservative systems without any symmetry; the key difficulty of the proof is proving the Palais–Smale condition and the non-constant property for the minimax critical point

79

Kinetic energy density functionals for non-periodic systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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)]...

Choly, Nicholas; Kaxiras, Efthimios

2001-01-01

80

Local response dispersion method in periodic systems: Implementation and assessment.  

Science.gov (United States)

We report the implementation of the local response dispersion (LRD) method in an electronic structure program package aimed at periodic systems and an assessment combined with the Perdew-Burke-Ernzerhof (PBE) functional and its revised version (revPBE). The real-space numerical integration was implemented and performed exploiting the electron distribution given by the plane-wave basis set. The dispersion-corrected density functionals revPBE+LRD was found to be suitable for reproducing energetics, structures, and electron distributions in simple substances, molecular crystals, and physical adsorptions. © 2014 Wiley Periodicals, Inc. PMID:25487530

Ikabata, Yasuhiro; Tsukamoto, Yusuke; Imamura, Yutaka; Nakai, Hiromi

2015-02-15

 
 
 
 
81

Generalized H2 Control Synthesis for Periodic Systems  

DEFF Research Database (Denmark)

A control synthesis of periodic processes is addressed in this paper. A class of linear discrete time periodic systems with performance specified by the generalized $H_2$ operator norm, is considered. The paper proposes an LMI solution to this problem, the sufficient and necessary conditions for solvability of $H_2$ suboptimal control are stated. An algorithm for state feedback control synthesis is provided. The findings are applied for the attitude control of a satellite equipped with electro-magnetic coils, which comprises a very attractive means of attitude corrections for small low-cost spacecraft missions.

Wisniewski, Rafal; Stoustrup, Jakob

2001-01-01

82

The gut mucosal immune system in the neonatal period.  

Science.gov (United States)

Invasive sepsis in the newborn period is a major cause of childhood morbidity and mortality worldwide. The infant immune system undoubtedly differs intrinsically from the mature adult immune system. Current understanding is that the newborn infant immune system displays a range of competencies and is developing rather than deficient. The infant gut mucosal immune system is complex and displays a plethora of phenotypic and functional irregularities that may be clinically important. Various factors affect and modulate the infant gut mucosal immune system: components of the intestinal barrier, the infant gut microbiome, nutrition and the maternal-infant hybrid immune system. Elucidation of the phenotypic distribution of immune cells, their functional significance and the mucosa-specific pathways used by these cells is essential to the future of research in the field of infant immunology. PMID:23682966

Battersby, Anna J; Gibbons, Deena L

2013-08-01

83

A family of Nikishin systems with periodic recurrence coefficients  

International Nuclear Information System (INIS)

Suppose we have a Nikishin system of p measures with the kth generating measure of the Nikishin system supported on an interval ?k subset of R with ?k ? ?k+1 = ? for all k. It is well known that the corresponding staircase sequence of multiple orthogonal polynomials satisfies a (p+2)-term recurrence relation whose recurrence coefficients, under appropriate assumptions on the generating measures, have periodic limits of period p. (The limit values depend only on the positions of the intervals ?k.) Taking these periodic limit values as the coefficients of a new (p+2)-term recurrence relation, we construct a canonical sequence of monic polynomials {Pn}n=0?, the so-called Chebyshev-Nikishin polynomials. We show that the polynomials Pn themselves form a sequence of multiple orthogonal polynomials with respect to some Nikishin system of measures, with the kth generating measure being absolutely continuous on ?k. In this way we generalize a result of the third author and Rocha [22] for the case p=2. The proof uses the connection with block Toeplitz matrices, and with a certain Riemann surface of genus zero. We also obtain strong asymptotics and an exact Widom-type formula for functions of the second kind of the Nikishin system for {Pn}n=0?. Bibliography: 27 titles.

84

Electrostatics of solvated systems in periodic boundary conditions  

Science.gov (United States)

Continuum solvation methods can provide an accurate and inexpensive embedding of quantum simulations in liquid or complex dielectric environments. Notwithstanding a long history and manifold applications to isolated systems in open boundary conditions, their extension to materials simulations, typically entailing periodic boundary conditions, is very recent, and special care is needed to address correctly the electrostatic terms. We discuss here how periodic boundary corrections developed for systems in vacuum should be modified to take into account solvent effects, using as a general framework the self-consistent continuum solvation model developed within plane-wave density-functional theory [O. Andreussi et al., J. Chem. Phys. 136, 064102 (2012), 10.1063/1.3676407]. A comprehensive discussion of real- and reciprocal-space corrective approaches is presented, together with an assessment of their ability to remove electrostatic interactions between periodic replicas. Numerical results for zero- and two-dimensional charged systems highlight the effectiveness of the different suggestions, and underline the importance of a proper treatment of electrostatic interactions in first-principles studies of charged systems in solution.

Andreussi, Oliviero; Marzari, Nicola

2014-12-01

85

Synchronous 231Pa/230Th Holocene variability from the Mendeleev and Lomonosov Ridges at mid-depths  

Science.gov (United States)

The Arctic Ocean contributes to global thermohaline circulation through export of intermediate and deep water through Fram Strait; however, the history of formation and circulation of Arctic waters at these depths is little known and presents a major challenge to paleoceanographers. Sedimentary measurements of the uranium-series radionuclides 231Pa and 230Th may provide a means of investigating the past dynamics of these deeper waters. We present 231Pa/230Th records from two well-dated box cores at mid-depths in the Arctic: PL-AR-94 BC 17 from 2255 m on the flank of the Mendeleev Ridge, Makarov Basin, and PL-94-AR BC 28 from 1990 m on the Lomonosov Ridge flank, Amundsen Basin. These records show synchronous millennial-scale variability through the Holocene, with peaks in 231Pa/230Th at 10.5, 7, and 5 ka, interspersed with low ratio values at 8, 6, and 4 ka. Indicators of surface ocean processes at these sites, such as particle fluxes and planktonic ?18O, do not show similar synchronous variation; nor do 231Pa/230Th records from shallower and deeper waters in the central Arctic. We therefore hypothesize that these millennial-scale variations in 231Pa/230Th ratios reflect paleoceanographic changes specific to mid-depth waters across Arctic subbasins, and that these common features may reflect a common source in the core flow of the Arctic Ocean Boundary Current between 1500 and 2500 m.

Hoffmann, S. S.; McManus, J. F.; Curry, W. B.; Brown-Leger, S.

2011-12-01

86

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] Abstract in english A history of the periodic table of the elements is presented, from the first tentative classifications, passing through Meyer and Mendeleev, up to recent speculations on super-heavy elements still to be synthesized. Many of the discussions and discoveries related to chemical elements and their prope [...] r periodic classification are also presented.

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

1997-02-01

87

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

88

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

89

Automatic Transmission Period Setting for Intermittent Periodic Transmission in Wireless Backhaul System  

Science.gov (United States)

Intermittent Periodic Transmission (IPT forwarding) has been proposed as an efficient packet relay method for wireless backhaul. In IPT forwarding, a source node sends packets to a destination node with a certain time interval (IPT duration) so that signal interference between relay nodes that send packets simultaneously are reduced and frequency reuse is realized which brings about an improvement of system throughput. However, optimum IPT duration setting for each node is a difficult problem which is not solved adequately yet. In this paper, we propose a new IPT duration setting protocol which employs some training packets to search for the optimum IPT duration for each node. A simulation and experiment show that the proposed method is not only very effective but also practical for wireless backhaul.

Jin, Guangri; Furukawa, Hiroshi

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 a 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

91

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

92

Periodically driven ergodic and many-body localized quantum systems  

Science.gov (United States)

We study dynamics of isolated quantum many-body systems whose Hamiltonian is switched between two different operators periodically in time. The eigenvalue problem of the associated Floquet operator maps onto an effective hopping problem. Using the effective model, we establish conditions on the spectral properties of the two Hamiltonians for the system to localize in energy space. We find that ergodic systems always delocalize in energy space and heat up to infinite temperature, for both local and global driving. In contrast, many-body localized systems with quenched disorder remain localized at finite energy. We support our conclusions by numerical simulations of disordered spin chains. We argue that our results hold for general driving protocols, and discuss their experimental implications.

Ponte, Pedro; Chandran, Anushya; Papi?, Z.; Abanin, Dmitry A.

2015-02-01

93

Periodic dynamic systems for infected hosts and mosquitoes  

Directory of Open Access Journals (Sweden)

Full Text Available A mathematical model for the purpose of analysing the dynamic of the populations of infected hosts anf infected mosquitoes when the populations of mosquitoes are periodic in time is here presented. By the computation of a parameter lambda (the spectral radius of a certain monodromy matrix one can state that either the infection peters out naturally (lambda 1 the infection becomes endemic. The model generalizes previous models for malaria by considering the case of periodic coefficients; it is also a variation of that for gonorrhea. The main motivation for the consideration of this present model was the recent studies on mosquitoes at an experimental rice irrigation system, in the South-Eastern region of Brazil.

Oliva W. M.

1996-01-01

94

Response of the Ionosphere-Plasmasphere System to Periodic Forcing  

Science.gov (United States)

The role of different mechanisms for generating periodic variability in the ionosphere and plasmasphere is studied in this dissertation. The impact of vertically propagating waves of lower atmospheric origin on introducing periodic spatial and temporal variability in the ionosphere and plasmasphere is first investigated. This is comprised of several different aspects. Initial focus is on the seasonal, local time, and altitude dependence of longitude variations due to nonmigrating tides in the F-region and topside ionosphere/plasmasphere using a combination of observations and numerical models. This is facilitated by the development of a new method for mitigating the effect of multipath on low-Earth orbit (LEO) satellite Global Positioning System (GPS) observations. The impact of large-scale changes in tropospheric convection due to the El-Nino Southern Oscillation on the ionosphere is also explored observationally. The influence of nonmigrating tides on the global ionosphere is revealed through study of the longitude variations in the solar quiet current system. Periodic temporal variability in the ionosphere due to planetary waves originating in the lower atmosphere is also investigated. The response of the global ionosphere to the quasi-16 day planetary wave is first presented. This is followed by observational evidence demonstrating that the nonlinear interaction between planetary waves and tides is the primary mechanism responsible for low-latitude ionospheric variability during sudden stratospheric warmings. Periodic temporal variability in the ionosphere and plasmasphere of solar origin is also studied. During the declining phase of solar cycle 23, near-Earth geospace was routinely disturbed due to high-speed solar wind streams emanating from solar coronal holes. The nature of the coronal holes was such that the Earth's upper atmosphere exhibited periodic behavior due to recurrent geomagnetic activity. A study of the latitude and local time response of the ionosphere to recurrent geomagnetic activity is performed herein. A method for estimating the location of the plasmapause from LEO GPS observations is also developed and applied to study periodic oscillations in the plasmapause.

Pedatella, Nicholas M.

95

Dimension Reduction Near Periodic Orbits of Hybrid Systems  

CERN Document Server

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

96

Discrete changes of current statistics in periodically driven stochastic systems  

International Nuclear Information System (INIS)

We demonstrate that the counting statistics of currents in periodically driven ergodic stochastic systems can show sharp changes of some of its properties in response to continuous changes of the driving protocol. To describe this effect, we introduce a new topological phase factor in the evolution of the moment generating function which is akin to the topological geometric phase in the evolution of a periodically driven quantum mechanical system with time-reversal symmetry. This phase leads to the prediction of a sign change for the difference of the probabilities to find even and odd numbers of particles transferred in a stochastic system in response to cyclic evolution of control parameters. The driving protocols that lead to this sign change should enclose specific degeneracy points in the space of control parameters. The relation between the topology of the paths in the control parameter space and the sign changes can be described in terms of the first Stiefel–Whitney class of topological invariants. (letter)

97

Periodic solutions to systems of reaction-diffusion equations  

Science.gov (United States)

Necessary and sufficient conditions are derived for the existence of temporally periodic 'dissipative structure' solutions in weak diffusion with the reaction rate terms dominant in a generic system of reaction-diffusion differential equations. The enumerator index i of the equations denotes the density or concentration of the ith participating molecular or biological species, and D sub i is the diffusivity constant for the ith species while Q sub i (c), an algebraic function of the n-tuple c, expresses the local rate of production of the ith species due to chemical reactions or biological interactions.

Rosen, G.

1976-01-01

98

Topological Changes in Periodicity Hubs of Dissipative Systems  

Science.gov (United States)

We reveal the existence of a new codimension-1 curve that involves a topological change in the structure of the chaotic invariant sets (attractors and saddles) in generic three-dimensional dissipative systems with Shilnikov saddle foci. This curve is related to the spiral-like structures of periodicity hubs that appear in the biparameter phase plane. We show how this curve configures the spiral structure (via the doubly superstable points) originated by the existence of Shilnikov homoclinics and how it separates two regions with different kinds of chaotic attractors or chaotic saddles. Inside each region, the topological structure is the same for both chaotic attractors and saddles.

Barrio, Roberto; Blesa, Fernando; Serrano, Sergio

2012-05-01

99

Periodic Solutions of Singular Hamiltonian Systems with Fixed Energies  

CERN Document Server

We use the variational minimizing method with a suitable constraint and a variant of the famous Benci-Rabinowitz's saddle point Theorem to study the existence of new non-trival periodic solutions with a prescribed energy for second order Hamiltonian systems with singular potentials $V\\in C^2(R^n\\backslash O,R)$ and $V\\in C^1(R^n\\backslash O,R)$ which may have an unbounded potential well, our results can be regarded as some complementaries of the well-known Theorems of Benci-Gluck-Ziller-Hayashi and Ambrosetti-Coti Zelati etc..

Hua, Qingqing

2011-01-01

100

Spin-boson models for periodic N-site systems  

Science.gov (United States)

The single/multi-mode spin-boson model provides a description for numerous two-level exciton-phonon and atom-cavity systems. Existing many-level extensions conserve symmetries but quickly become intractable due to the inclusion of multiple interacting modes. Other ad-hoc single-mode extensions contain arbitrary numbers of parameters and often ignore the symmetries of their respective systems. This work presents a simple model for the interaction of a periodic system of N coupled sites with one or more non-interacting boson modes using a minimal number of parameters [1]. A group theoretic approach allows one to partially diagonalize the Hamiltonian, providing numerical advantages, physical insight, and a gateway to accurate approximations. The single-mode two-site system reduces to the single-mode spin-boson model, also known as the Rabi Hamiltonian. Two higher dimensional generalizations are reviewed in the exciton-phonon/atom-field interpretations and related to a new integrability criterion [2]. The model predicts that 2N-level systems have parity symmetry and that the ground state of certain four-level atom-cavity systems will undergo parity change at large coupling. [4pt] [1] V. V. Albert, arXiv:1112.0849 [0pt] [2] D. Braak, PRL 107, 100401 (2011)

Albert, Victor V.

2012-02-01

 
 
 
 
101

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

102

Maximum population transfer in a periodically driven quantum system  

Science.gov (United States)

We study the dynamics of a two-level quantum system under the influence of sinusoidal driving in the intermediate-frequency regime. Analyzing the Floquet quasienergy spectrum, we find combinations of the field parameters for which population transfer is optimal and takes place through a series of well-defined steps of fixed duration. We also show how the corresponding evolution operator can be approximated at all times by a very simple analytical expression. We propose this model as being specially suitable for treating periodic driving at avoided crossings found in complex multilevel systems, and thus show a relevant application of our results to designing a control protocol in a realistic molecular model.

Poggi, P. M.; Arranz, F. J.; Benito, R. M.; Borondo, F.; Wisniacki, D. A.

2014-12-01

103

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

CERN Document Server

Building on previous work, a new search of the SuperWASP archive was carried out to identify eclipsing binary systems near the short-period limit. 143 candidate objects were detected with orbital periods between 16000 and 20000 s, of which 97 are new discoveries. Period changes significant at 1 sigma or more were detected in 74 of these objects, and in 38 the changes were significant at 3 sigma or more. The significant period changes observed followed an approximately normal distribution with a half-width at half-maximum of ~0.1 s/yr. There was no apparent relationship between period length and magnitude or direction of period change. Amongst several interesting individual objects studied, 1SWASP J093010.78+533859.5 is presented as a new doubly eclipsing quadruple system, consisting of a contact binary with a 19674.575 s period and an Algol-type binary with a 112799.109 s period, separated by 66.1 AU, being the sixth known system of this type.

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

2012-01-01

104

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

105

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.

2007-10-01

106

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

107

Delayed feedback control of periodic orbits in autonomous systems  

CERN Document Server

For controlling periodic orbits with delayed feedback methods the periodicity has to be known a priori. We propose a simple scheme, how to detect the period of orbits from properties of the control signal, at least if a periodic but nonvanishing signal is observed. We analytically derive a simple expression relating the delay, the control amplitude, and the unknown period. Thus, the latter can be computed from experimentally accessible quantities. Our findings are confirmed by numerical simulations and electronic circuit experiments

Just, W; Möckel, J; Reibold, E; Benner, H; Just, Wolfram; Reckwerth, Dirk; Möckel, Johannes; Reibold, Ekkehard; Benner, Hartmut

1998-01-01

108

Delayed feedback control of periodic orbits in autonomous systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

For controlling periodic orbits with delayed feedback methods the periodicity has to be known a priori. We propose a simple scheme, how to detect the period of orbits from properties of the control signal, at least if a periodic but nonvanishing signal is observed. We analytically derive a simple expression relating the delay, the control amplitude, and the unknown period. Thus, the latter can be computed from experimentally accessible quantities. Our findings are confirmed ...

Just, Wolfram; Reckwerth, Dirk; Mo?ckel, Johannes; Reibold, Ekkehard; Benner, Hartmut

1998-01-01

109

XVIII Mendeleev congress on general and applied chemistry. Summaries of reports in five volumes. Volume 4. New methods and devices for chemical investigations and analysis. Chemical education. Actual problems of high energy chemistry. Biomolecular chemistry and biotechnology  

International Nuclear Information System (INIS)

The 4 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 methods and devices for chemical investigations and analysis, education, high energy chemistry, biomolecular chemistry and biotechnology

110

Comment on "Optimal Periodic Orbits of Chaotic Systems"  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In a recent Letter, Hunt and Ott argued that SHORT-period unstable periodic orbits (UPOs) would be the invariant sets associated with a chaotic attractor that are most likely to optimize the time average of some smooth scalar performance function. In this Comment, we show that their conclusion does not hold generally and that optimal time averages may specifically require long-period UPOs. This situation can arise when long-period UPOs are able to spend substantial amounts o...

Zoldi, Scott M.; Greenside, Henry S.

1997-01-01

111

On the stability of periodically time-dependent quantum systems  

CERN Document Server

The main motivation of this article is to derive sufficient conditions for dynamical stability of periodically driven quantum systems described by a Hamiltonian H(t), i.e., conditions under which it holds sup_{t in R} | (psi(t),H(t) psi(t)) |<\\infty where psi(t) denotes a trajectory at time t of the quantum system under consideration. We start from an analysis of the domain of the quasi-energy operator. Next we show, under certain assumptions, that if the spectrum of the monodromy operator U(T,0) is pure point then there exists a dense subspace of initial conditions for which the mean value of energy is uniformly bounded in the course of time. Further we show that if the propagator admits a differentiable Floquet decomposition then || H(t) psi(t) || is bounded in time for any initial condition psi(0), and one employs the quantum KAM algorithm to prove the existence of this type of decomposition for a fairly large class of H(t). In addition, we derive bounds uniform in time on transition probabilities betwe...

Duclos, Pierre; Stovicek, Pavel; Vittot, Michel

2007-01-01

112

Origin of authigenic calcite and aragonite in pelagic sediments of the Mendeleev Ridge (Arctic Ocean) and their paleoceanographicimplications  

Science.gov (United States)

Carbonate minerals were discovered from the giant box core (PS72/410-1) of the pelagic sediments recovered from the Canadian Arctic across the central Mendeleev Ridge (Station location= Lat. 80°30.37"N, Long. 175°44.38"W) during the Arctic cruise by Polarstern in 2008. The core was 39 cm long and was collected from the water depth of 1802 meters. The sediments show various colours from grey to brown as previously reported in other Arctic pelagic sediments. The sediments include planktonic foraminifers together with carbonate minerals. The contents of planktonic foraminifers and carbonate minerals vary with core depth, however these carbonate minerals are present through the whole sequence except for a few centimetres. After wet sieving, coarse fractions were texturally examined with binocular microscope and SEM, and stable isotope and trace element contents were obtained. Mineralogy of carbonate minerals were determined using crystal shapes and qualitative Sr contents by EDAX together with trace element analysis. The carbonates are composed of high Mg-calcite, low Mg-calcite and aragonite. Aragonite crystals show (1) radiating fibrous texture, (2) randomly oriented fibrous texture, (3) spherulitic fibrous texture, and (4) bladed texture, and calcite crystals show (1) foliated texture, (2) randomly bladed texture, (3) spherulitic fibrous texture, and (4) equant texture. Various crystal shapes of aragonite and calcite together with clear growth shapes of the crystals suggest that they are inorganic in origin. Highly enriched carbon isotope compositions (?13C = 0 ~ +5‰ vs. PDB) strongly indicate that they formed in methanogenic zone below sediment/water interface by the reaction between anoxic pore fluids and host sediments induced by methanogenic bacteria. However, a wide range of oxygen isotope values (?18O = -5 ~ +5‰ vs. PDB) may indicate that porewater has been changed due to reaction between residual seawater and volcanic sediments. Four types of stable isotope compositions are recognized and they imply complicated evolution of early diagenetic pore waters. Because the core sediments are not organic-rich, the presence of the authigenic carbonates may be related to paleoceanograhic conditions of the Arctic Ocean which resulted in anoxic pore water conditions just a few centimetres below the sediment/water interface. Trace elemental compositions show clear divisions at the boundary of ca. 10 cm in core depth. Carbonates found shallower than this depth show higher Mg, Mn, Fe and Sr compositions which may imply paleoenvironmental changes with time.

Woo, K. S.; Ji, H. S.; Nam, S.; Stein, R. H.; Mackensen, A.; Matthiessen, J. J.

2013-12-01

113

M|G|? Queue Systems in the Pandemic Period Study  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Even after the Humanity efforts and great success in infectious diseases control, still epidemics happen, being the annual influenza outbreaks examples of those occurrences. To forecast the epidemic period length is very important because, in this period, it is necessary to strengthen the health care, demanding extra availability in human and material resources, with a huge increase of expenses. More pertinently, this happens with the pandemic period, since a pandemic is an epidemic w...

Ferreira, Manuel Alberto M.

2014-01-01

114

A Long-Period Grating Sensor System Monitoring Loads on a Wind Turbine Blade  

DEFF Research Database (Denmark)

We demonstrate the utilization of a blade load sensor system based on two identical Long-Period Gratings in a Mach-Zehnder configuration. The experimental results demonstrate the potential of a Long-Period Grating based load interrogation system.

Glavind, Lars; Buggy, Stephen

2014-01-01

115

Dynamical Localization in Quasi-Periodic Driven Systems  

CERN Document Server

We investigate how the time dependence of the Hamiltonian determines the occurrence of Dynamical Localization (DL) in driven quantum systems with two incommensurate frequencies. If both frequencies are associated to impulsive terms, DL is permanently destroyed. In this case, we show that the evolution is similar to a decoherent case. On the other hand, if both frequencies are associated to smooth driving functions, DL persists although on a time scale longer than in the periodic case. When the driving function consists of a series of pulses of duration $\\sigma$, we show that the localization time increases as $\\sigma^{-2}$ as the impulsive limit, $\\sigma\\to 0$, is approached. In the intermediate case, in which only one of the frequencies is associated to an impulsive term in the Hamiltonian, a transition from a localized to a delocalized dynamics takes place at a certain critical value of the strength parameter. We provide an estimate for this critical value, based on analytical considerations. We show how, i...

Abal, G; Romanelli, A; Schifino, A C S; Siri, R

2001-01-01

116

The Higgs Boson in the Periodic System of Elementary Particles  

Directory of Open Access Journals (Sweden)

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

Ding-Yu Chung

2013-04-01

117

Exponential dichotomy of nonautonomous periodic systems in terms of the boundedness of certain periodic Cauchy problems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We prove that a family of $q$-periodic continuous matrix valued function ${A(t)}_{tin mathbb{R}}$ has an exponential dichotomy with a projector $P$ if and only if $int_0^t e^{imu s}U(t,s)Pds$ is bounded uniformly with respect to the parameter $mu$ and the solution of the Cauchy operator Problem $$displaylines{ dot{Y}(t)=-Y(t)A(t)+ e^{i mu t}(I-P) ,quad tgeq s cr Y(s)=0, }$$ has a limit in $mathcal{L}(mathbb{C}^n)$ as s tends to $-infty$ which is bounded uniformly with respect to the...

Dhaou Lassoued

2013-01-01

118

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

119

Dynamical System Approach to a Coupled Dispersionless System: Localized and Periodic Traveling Waves  

International Nuclear Information System (INIS)

We investigate the dynamical behavior of a coupled dispersionless system describing a current-conducting string with infinite length within a magnetic field. Thus, following a dynamical system approach, we unwrap typical miscellaneous traveling waves including localized and periodic ones. Studying the relative stabilities of such structures through their energy densities, we find that under some boundary conditions, localized waves moving in positive directions are more stable than periodic waves which in contrast stand for the most stable traveling waves in another boundary condition situation. (general)

120

Gravitational Waves from Periodic Three-Body Systems  

CERN Document Server

Three bodies moving in a periodic orbit under the influence of Newtonian gravity ought to emit gravitational waves. We have calculated the gravitational radiation quadrupolar waveforms and the corresponding luminosities for the 13+11 recently discovered three-body periodic orbits in Newtonian gravity. These waves clearly allow one to distinguish between their sources: all 13+11 orbits have different waveforms and their luminosities (evaluated at the same orbit energy and body mass) vary by up to 13 orders of magnitude in the mean, and up to 20 orders of magnitude for the peak values.

Dmitrašinovi?, V; Hudomal, Ana

2015-01-01

 
 
 
 
121

High Frequency Stochastic Resonance in Periodically Driven Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

High frequency stochastic resonance (SR) phenomena, associated with fluctuational transitions between coexisting periodic attractors, have been investigated experimentally in an electronic model of a single-well Duffing oscillator bistable in a nearly resonant field of frequency $\\omega_F$. It is shown that, with increasing noise intensity, the signal/noise ratio (SNR) for a signal due to a weak trial force of frequency $\\Omega \\sim \\omega_F$ at first decreases, then {\\it in...

Dykman, M. I.; Luchinsky, D. G.; Mannella, R.; Mcclintock, P. V. E.; Soskin, S. M.; Stein, N. D.; Stocks, N. G.

1993-01-01

122

Convergent series for quasi-periodically forced strongly dissipative systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study the ordinary differential equation ${\\varepsilon}\\ddot x+\\dot x + {\\varepsilon} g(x) = {\\varepsilon} f(\\omega t)$, with $f$ and $g$ analytic and $f$ quasi-periodic in $t$ with frequency vector $\\omega\\in R^{d}$. We show that if there exists $c_0\\in R$ such that $g(c_0)$ equals the average of $f$ and the first non-zero derivative of $g$ at $c_0$ is of odd order $n$, then, for ${\\varepsilon}$ small enough and under very mild Diophantine conditions on $\\omega$, there e...

Corsi, Livia; Feola, Roberto; Gentile, Guido

2012-01-01

123

On the stabilization of periodic orbits for discrete time chaotic systems  

International Nuclear Information System (INIS)

In this Letter we consider the stabilization problem of unstable periodic orbits of discrete time chaotic systems. We propose a novel and simple periodic delayed feedback law and present some stability results. These results show that all hyperbolic periodic orbits as well as some non-hyperbolic periodic orbits can be stabilized with the proposed method. The stability proofs also give the possible feedback gains which achieve stabilization. We will also present some simulation results

124

Mobility induces global synchronization of oscillators in periodic extended systems  

International Nuclear Information System (INIS)

We study the synchronization of locally coupled noisy phase oscillators that move diffusively in a one-dimensional ring. Together with the disordered and the globally synchronized states, the system also exhibits wave-like states displaying local order. We use a statistical description valid for a large number of oscillators to show that for any finite system there is a critical mobility above which all wave-like solutions become unstable. Through Langevin simulations, we show that the transition to global synchronization is mediated by a shift in the relative size of attractor basins associated with wave-like states. Mobility disrupts these states and paves the way for the system to attain global synchronization.

125

Spectral singularities in PT-symmetric periodic finite-gap systems  

CERN Document Server

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

Correa, Francisco

2012-01-01

126

Computer Assisted 'Proof' of the Global Existence of Periodic Orbits in the R\\"ossler System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The numerical optimized shooting method for finding periodic orbits in nonlinear dynamical systems was employed to determine the existence of periodic orbits in the well-known R\\"ossler system. By optimizing the period $T$ and the three system parameters, $a$, $b$ and $c$, simultaneously, it was found that, for any initial condition $(x_0,y_0,z_0) \\in \\Re^3$, there exists at least one set of optimized parameters corresponding to a periodic orbit passing through $ (x_0,y_0,z_...

Botha, A. E.; Dednam, W.

2014-01-01

127

Portable system for periodical verification of area monitors for neutrons  

International Nuclear Information System (INIS)

The Neutrons Laboratory develops a project viewing the construction of a portable test system for verification of functioning conditions of neutron area monitors. This device will allow to the users the verification of the calibration maintenance of his instruments at the use installations, avoiding the use of an inadequate equipment related to his answer to the neutron beam response

128

The direct approach to gravitation and electrostatics method for periodic systems  

DEFF Research Database (Denmark)

The direct approach to gravitation and electrostatics (DAGE) algorithm is an accurate, efficient, and flexible method for calculating electrostatic potentials. In this paper, we show that the algorithm can be easily extended to consider systems with many different kinds of periodicities, such as crystal lattices, surfaces, or wires. The accuracy and performance are nearly the same for periodic and aperiodic systems. The electrostatic potential for semiperiodic systems, namely defects in crystal lattices, can be obtained by combining periodic and aperiodic calculations. The method has been applied to an ionic model system mimicking NaCl, and to a corresponding covalent model system.

Losilla, Sergio Alberto; Sundholm, D

2010-01-01

129

18 CFR 301.4 - Exchange Period Average System Cost determination.  

Science.gov (United States)

... AVERAGE SYSTEM COST METHODOLOGY FOR...Period Average System Cost determination...CSERVE—Customer Service. (vii) COAL...NATGAS—Natural Gas. (xiv) NFUEL... (xxi) TMN—Transmission Maintenance. (xxii...Bonneville will base the costs of power...

2010-04-01

130

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

CERN Document Server

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

131

Enhancing Quantum Effects via Periodic Modulations in Optomechanical Systems  

CERN Document Server

Parametrically modulated optomechanical systems have been recently proposed as a simple and efficient setting for the quantum control of a micromechanical oscillator: relevant possibilities include the generation of squeezing in the oscillator position (or momentum) and the enhancement of entanglement between mechanical and radiation modes. In this paper we further investigate this new modulation regime, considering an optomechanical system with one or more parameters being modulated over time. We first apply a sinusoidal modulation of the mechanical frequency and characterize the optimal regime in which the visibility of purely quantum effects is maximal. We then introduce a second modulation on the input laser intensity and analyze the interplay between the two. We find that an interference pattern shows up, so that different choices of the relative phase between the two modulations can either enhance or cancel the desired quantum effects.

Farace, Alessandro

2012-01-01

132

Periodic inspection for safety of CANDU heat transport piping systems  

International Nuclear Information System (INIS)

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

133

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

CERN Document Server

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

Iwao, Shinsuke; Isojima, Shin

2012-01-01

134

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

International Nuclear Information System (INIS)

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

135

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

Science.gov (United States)

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

Iwao, Shinsuke; Nagai, Hidetomo; Isojima, Shin

2012-10-01

136

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

137

The computerized reactor period measurement system for China fast burst reactor-II  

International Nuclear Information System (INIS)

The article simply introduces the hardware, principle, and software of the computerized reactor period measurement system for China Fast Burst Reactor-II (CFBR-II). It also gives the relation between fission yield and pre-reactivity of CFBR-II reactor system of bared reactor with decoupled-component and system of bared reactor with multiple light-material. The computerized measurement system makes the reactor period measurement into automatical and intelligent and also improves the speed and precision of period data on-line process

138

The orbital periods of three sdB eclipsing binary systems  

Science.gov (United States)

Recent timings of eclipses made between 2011 and 2014 are presented for three binary systems with hot subdwarf primary stars, AA Dor, NY Vir and EC 10246-2707. In the case of AA Dor, the period remains constant. In NY Vir, a rapidly pulsating sdBVr with a cool companion, the period change now appears more complex than can be described by a simple quadratic. EC 10246-2707, which has previously appeared to have a constant period, now appears to be showing a significant period increase. The effect of gravitational radiation in HW Vir-like systems is briefly discussed.

Kilkenny, D.

2014-12-01

139

Period two implies chaos for a class of ODEs: a dynamical system approach  

CERN Document Server

The aim of this note is to set in the field of dynamical systems a recent theorem by Obersnel and Omari about the presence of periodic solutions of all periods for a class of scalar time-periodic first order differential equations without uniqueness, provided a subharmonic solution (and thus, for instance, a solution of period two) does exist. Indeed, making use of the Bebutov flow, we try to clarify in what sense the term "chaos" has to be understood and which dynamical features can be inferred for the system under analysis.

Pireddu, Marina

2009-01-01

140

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a theoretical calibration of the RR Lyrae period-luminosity-color and period-color-color relations in the multiband uvby Stroemgren photometric system. Our theoretical work is based on calculations of synthetic horizontal branches (HBs) for four different metallicities, fully taking into account evolutionary effects for a wide range in metallicities and HB morphologies. While our results show that "pure" period-luminosity and period-color relations do not exist in...

Corte?s, C.; Catelan, M.

2008-01-01

 
 
 
 
141

Optimized shooting method for finding periodic orbits of nonlinear dynamical systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An alternative numerical method is developed to find stable and unstable periodic orbits of nonlinear dynamical systems. The method exploits the high-efficiency of the Levenberg-Marquardt algorithm for medium-sized problems and has the additional advantage of being relatively simple to implement. It is also applicable to both autonomous and non-autonomous systems. As an example of its use, it is employed to find periodic orbits in the R\\"ossler system, a coupled R\\"ossler sy...

Dednam, W.; Botha, A. E.

2014-01-01

142

Immune system adaptations during competition period in female cross-country skiers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Stenholm, Johanna. Immune system adaptations during competition period in female cross-country skiers. Master’s Thesis in Exercise Physiology, Department of Biology of Physical Activity. University of Jyväskylä. 95pp. Purpose. This study was undertaken to characterize the extent of immune and endocrine changes in competition period and related to two competition weekends in well trained athletes in different parts of the competition period. An additional purpose was to evaluate if the...

Stenholm, Johanna

2011-01-01

143

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

DEFF Research Database (Denmark)

Long term prediction of maximum water levels and combined sewer overflow (CSO) in drainage systems are associated with large uncertainties. Especially on rainfall inputs, parameters, and assessment of return periods. This paper proposes a Monte Carlo based methodology for stochastic prediction of both maximum water levels as well as CSO volumes based on operations of the urban drainage model MOUSE (Lindberg and Joergensen 1986) in a single catchment case study. Results show quite a wide confidence interval of the model predictions especially on the large return periods. Traditionally, return periods of drainage system predictions are based on ranking, but this paper proposes a new methodology for the assessment of return periods. Based on statistics of characteristic rainfall parameters and correlation with drainage system predictions, it is possible to predict return periods more reliably, and with smaller confidence bands compared to the traditional methodology.

Thorndahl, SØren

2009-01-01

144

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

Energy Technology Data Exchange (ETDEWEB)

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.

Souza, S.L.T. de, E-mail: thomaz@ufsj.edu.br [Departamento de Física e Matemática, Universidade Federal de São João del-Rei, Ouro Branco, MG (Brazil); Lima, A.A. [Escola de Farmácia, Universidade Federal de Ouro Preto, Ouro Preto, MG (Brazil); Caldas, I.L. [Instituto de Física, Universidade de São Paulo, São Paulo, SP (Brazil); Medrano-T, R.O. [Departamento de Ciências Exatas e da Terra, Universidade Federal de São Paulo, Diadema, SP (Brazil); Guimarães-Filho, Z.O. [Aix-Marseille Univ., CNRS PIIM UMR6633, International Institute for Fusion Science, Marseille (France)

2012-03-12

145

Hopf-pitchfork bifurcation and periodic phenomena in nonlinear financial system with delay  

International Nuclear Information System (INIS)

Highlights: ? We derive the unfolding of a financial system with Hopf-pitchfork bifurcation. ? We show the coexistence of a pair of stable small amplitudes periodic solutions. ? At the same time, also there is a pair of stable large amplitudes periodic solutions. ? Chaos can appear by period-doubling bifurcation far away from Hopf-pitchfork value. ? The study will be useful for interpreting economics phenomena in theory. - Abstract: In this paper, we identify the critical point for a Hopf-pitchfork bifurcation in a nonlinear financial system with delay, and derive the normal form up to third order with their unfolding in original system parameters near the bifurcation point by normal form method and center manifold theory. Furthermore, we analyze its local dynamical behaviors, and show the coexistence of a pair of stable periodic solutions. We also show that there coexist a pair of stable small-amplitude periodic solutions and a pair of stable large-amplitude periodic solutions for different initial values. Finally, we give the bifurcation diagram with numerical illustration, showing that the pair of stable small-amplitude periodic solutions can also exist in a large region of unfolding parameters, and the financial system with delay can exhibit chaos via period-doubling bifurcations as the unfolding parameter values are far away from the critical point of the Hopf-pitchfork bifurcation.

146

Periodic solutions for second-order Hamiltonian systems with the p-Laplacian  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, we investigate the periodic solutions of Hamiltonian system with the p-Laplacian. By using Mountain Pass Theorem the existence of at least one periodic solution is obtained, Furthermore, under suitable assumptions, we obtain the existence of infinitely many solutions via $Z_2$-symmetric version of the Mountain Pass Theorem.

Weigao Ge

2006-10-01

147

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

148

Stochastic period-doubling bifurcation in biharmonic driven Duffing system with random parameter  

International Nuclear Information System (INIS)

Stochastic period-doubling bifurcation is explored in a forced Duffing system with a bounded random parameter as an additional weak harmonic perturbation added to the system. Firstly, the biharmonic driven Duffing system with a random parameter is reduced to its equivalent deterministic one, and then the responses of the stochastic system can be obtained by available effective numerical methods. Finally, numerical simulations show that the phase of the additional weak harmonic perturbation has great influence on the stochastic period-doubling bifurcation in the biharmonic driven Duffing system. It is emphasized that, different from the deterministic biharmonic driven Duffing system, the intensity of random parameter in the Duffing system can also be taken as a bifurcation parameter, which can lead to the stochastic period-doubling bifurcations

149

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)

150

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

CERN Document Server

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

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

2006-01-01

151

Evolution with size in a locally periodic system: scattering and deterministic maps  

International Nuclear Information System (INIS)

In this paper, we study the evolution of the wavefunction with the system size in a locally periodic structure. In particular, we analyse the dependence of the wavefunction with the number of unit cells, which also reflects information about its spatial behaviour in the system. We reduce the problem to a nonlinear map and find an equivalence of its energy regions of single periodicity and weak chaos, with the forbidden and allowed bands of the fully periodic system, respectively. At finite size the wavefunction decays exponentially with the system size, as well as in space, when the energy lies inside a region of single periodicity, while for energies in the weak chaotic region it never decays. At the transition between those regions the wavefunction still decays but in a q-exponential form; we find that the decay length is a half of the mean free path, which is larger than the lattice constant. (paper)

152

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

153

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

154

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

155

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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; Pendry, John B.

2011-01-01

156

Spreading Speeds and Linear Determinacy for Two Species Competition Systems with Nonlocal Dispersal in Periodic Habitats  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The current paper is concerned with the existence of spreading speeds and linear determinacy for two species competition systems with nonlocal dispersal in time and space periodic habitats. The notion of spreading speed intervals for such a system is first introduced via the natural features of spreading speeds. The existence and lower bounds of spreading speed intervals are then established. When the periodic dependence of the habitat is only on the time variable, the exist...

Kong, Liang; Rawal, Nar; Shen, Wenxian

2014-01-01

157

Bifurcation analysis and control of periodic solutions changing into invariant tori in Langford system  

International Nuclear Information System (INIS)

Bifurcation characteristics of the Langford system in a general form are systematically analysed, and nonlinear controls of periodic solutions changing into invariant tori in this system are achieved. Analytical relationship between control gain and bifurcation parameter is obtained. Bifurcation diagrams are drawn, showing the results of control for secondary Hopf bifurcation and sequences of bifurcations route to chaos. Numerical simulations of quasi-periodic tori validate analytic predictions

158

Stochastic Resonance in Time-delayed Bistable Systems Driven by Weak Periodic Signal  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study theoretically a bistable systems with time-delayed feedback driven by weak periodic force. The effective potential function and the steady-state probability density are derived. The delay time and the strength of its feedback can change the shapes of the potential wells. In the adiabatic approximation, the signal-to-noise ratio (SNR) of the system with a weak periodic force is obtained. The time-delayed feedback modulates the magnitude of SNR by changing the shape o...

Shao, Rui-hua; Chen, Yong

2008-01-01

159

Linear time periodic modeling of power electronic devices for power system harmonic analysis and simulation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents an analytical frequency-domain method for harmonic estimation able to evaluate harmonics and interharmonics and to capture the coupling between frequencies. It is based on the linear time – periodic system theory as a result of the periodic behaviour of the state variables in steady state operation. It consists of describing the considered system with a set of differential equations, presenting them in a matrix form in the frequency domain by decomposition of the convert...

Ignatova, Vanya; Bacha, Seddik; Granjon, Pierre; Retie?re, Nicolas

2004-01-01

160

Validation of distributed periodic real-time systems using CAN protocol with finite automata  

Digital Repository Infrastructure Vision for European Research (DRIVER)

‘In a previous work, we have defined a temporal model based on regular languages to validate periodic real-time systems: the feasability decisional process is expressed by means of algebraic operations on languages, such as intersection, Hadamard product, and language center computing. Here, we describe how this model can be used to validate periodic distributed real-time systems. We base this description on the example of the CAN network protocol.

Largeteau-skapin, Gae?lle; Geniet, Dominique; Dubernard, Jean-philippe

2002-01-01

 
 
 
 
161

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

CERN Document Server

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

DaCunha, Jeffrey J

2009-01-01

162

Non-existence of periodic solutions in fractional-order dynamical systems and a remarkable difference between integer and fractional-order derivatives of periodic functions  

CERN Document Server

Using the Mellin transform approach, it is shown that, in contrast with integer-order derivatives, the fractional-order derivative of a periodic function cannot be a function with the same period. The three most widely used definitions of fractional-order derivatives are taken into account, namely, the Caputo, Riemann-Liouville and Grunwald-Letnikov definitions. As a consequence, the non-existence of exact periodic solutions in a wide class of fractional-order dynamical systems is obtained. As an application, it is emphasized that the limit cycle observed in numerical simulations of a simple fractional-order neural network cannot be an exact periodic solution of the system.

Kaslik, Eva

2011-01-01

163

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

CERN Document Server

We study properties of basic solutions in systems with dime delays and $S^1$-symmetry. Such basic solutions are relative equilibria (CW solutions) and relative periodic solutions (MW solutions). It follows from the previous theory that the number of CW solutions grows generically linearly with time delay $\\tau$. Here we show, in particular, that the number of relative periodic solutions grows generically as $\\tau^2$ when delay increases. Thus, in such systems, the relative periodic solutions are more abundant than relative equilibria. The results are directly applicable to, e.g., Lang-Kobayashi model for the lasers with delayed feedback. We also study stability properties of the solutions for large delays.

Yanchuk, Serhiy

2013-01-01

164

The Period-Ratio and Mass-Ratio Correlation in Extra-Solar Multiple Planetary Systems  

CERN Document Server

Employing the data from orbital periods and masses of extra-solar planets in 166 multiple planetary systems, the period-ratio and mass-ratio of adjacent planet pairs are studied. The correlation between the period-ratio and mass-ratio is confirmed and found to have a correlation coefficient of 0.5303 with a 99% confidence interval (0.3807, 0.6528). A comparison with the distribution of synthetic samples from a Monte Carlo simulation reveals the imprint of planet-planet interactions on the formation of adjacent planet pairs in multiple planetary systems.

Jiang, Ing-Guey; Hung, Wen-Liang

2015-01-01

165

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

166

Occurrence of periodic Lame functions at bifurcations in chaotic Hamiltonian systems  

International Nuclear Information System (INIS)

We investigate cascades of isochronous pitchfork bifurcations of straight-line librating orbits in some two-dimensional Hamiltonian systems with mixed phase space. We show that the new bifurcated orbits, which are responsible for the onset of chaos, are given analytically by the periodic solutions of the Lame equation as classified in 1940 by Ince. In Hamiltonians with C2? symmetry, they occur alternatingly as Lame functions of period 2K and 4K, respectively, where 4K is the period of the Jacobi elliptic function appearing in the Lame equation. We also show that the two pairs of orbits created at period-doubling bifurcations of island-chain type are given by two different linear combinations of algebraic Lame functions with period 8K. (author)

167

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

Directory of Open Access Journals (Sweden)

Full Text Available This study investigates the problem of integrity against actuator failures for networked control systems under variable-period sampling. Assuming that the distance between any two consecutive sampling instants is less than a given bound, by using the input delay approach, the networked control systems under variable-period sampling are transformed into the continuous-time networked control systems under time-varying delays. Then the existence conditions of guaranteed cost fault-tolerant control law is testified in terms of the Lyapunov stability theory combined with Linear Matrix Inequalities (LMIs. Furthermore, the guaranteed cost fault-tolerant controller gain and the minimization guaranteed cost can be obtained by solving a minimization problem. A numerical simulation example demonstrates the conclusions are feasible and effective. The proposed control method resolves the problems of variable-period sampling and actuator failures, which meets the requirements in industrial networked control systems.

Xuan Li

2009-01-01

168

Local electric dipole moments for periodic systems via density functional theory embedding  

Science.gov (United States)

We describe a novel approach for the calculation of local electric dipole moments for periodic systems. Since the position operator is ill-defined in periodic systems, maximally localized Wannier functions based on the Berry-phase approach are usually employed for the evaluation of local contributions to the total electric dipole moment of the system. We propose an alternative approach: within a subsystem-density functional theory based embedding scheme, subset electric dipole moments are derived without any additional localization procedure, both for hybrid and non-hybrid exchange-correlation functionals. This opens the way to a computationally efficient evaluation of local electric dipole moments in (molecular) periodic systems as well as their rigorous splitting into atomic electric dipole moments. As examples, Infrared spectra of liquid ethylene carbonate and dimethyl carbonate are presented, which are commonly employed as solvents in Lithium ion batteries.

Luber, Sandra

2014-12-01

169

Implementing Multi-Periodic Critical Systems: from Design to Code Generation  

CERN Document Server

This article presents a complete scheme for the development of Critical Embedded Systems with Multiple Real-Time Constraints. The system is programmed with a language that extends the synchronous approach with high-level real-time primitives. It enables to assemble in a modular and hierarchical manner several locally mono-periodic synchronous systems into a globally multi-periodic synchronous system. It also allows to specify flow latency constraints. A program is translated into a set of real-time tasks. The generated code (\\C\\ code) can be executed on a simple real-time platform with a dynamic-priority scheduler (EDF). The compilation process (each algorithm of the process, not the compiler itself) is formally proved correct, meaning that the generated code respects the real-time semantics of the original program (respect of periods, deadlines, release dates and precedences) as well as its functional semantics (respect of variable consumption).

Forget, Julien; Lesens, David; Pagetti, Claire

2010-01-01

170

Implementing Multi-Periodic Critical Systems: from Design to Code Generation  

Directory of Open Access Journals (Sweden)

Full Text Available This article presents a complete scheme for the development of Critical Embedded Systems with Multiple Real-Time Constraints. The system is programmed with a language that extends the synchronous approach with high-level real-time primitives. It enables to assemble in a modular and hierarchical manner several locally mono-periodic synchronous systems into a globally multi-periodic synchronous system. It also allows to specify flow latency constraints. A program is translated into a set of real-time tasks. The generated code (C code can be executed on a simple real-time platform with a dynamic-priority scheduler (EDF. The compilation process (each algorithm of the process, not the compiler itself is formally proved correct, meaning that the generated code respects the real-time semantics of the original program (respect of periods, deadlines, release dates and precedences as well as its functional semantics (respect of variable consumption.

Julien Forget

2010-03-01

171

On the control of linear systems using two level periodic output feedback.  

Science.gov (United States)

A class of second order linear time-invariant systems which are unstable for any constant feedback but which are stabilized by a two level periodic feedback is identified. Necessary and sufficient conditions for this type of stabilization are found. In addition, the sensitivity of the closed-loop system to changes in feedback gains is investigated.

Welch, R. V.; Levine, W. S.

1972-01-01

172

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

173

A finite temperature linear tetrahedron method for electronic structure calculations of periodic systems.  

Science.gov (United States)

A finite-temperature linear tetrahedron method for electronic structure calculations of periodic systems is developed. When compared to widely used simple temperature broadening, the number of k points necessary for accurate integration at finite temperatures is reduced. The utility of the method is demonstrated with benchmark calculations on 1D, 2D, and 3D systems. PMID:15281843

Yazyev, Oleg V; Brothers, Edward N; Kudin, Konstantin N; Scuseria, Gustavo E

2004-08-01

174

Stabilization of unstable periodic attractors of complex damped non-linear dynamical systems  

International Nuclear Information System (INIS)

In the recent paper [Int. J. Non-Linear Mech. 35 (2000) 309], periodic attractors were studied for a class of complex damped non-linear dynamical systems of the form:z-double dot+?2z+?z-dotf(z,z-bar,z-dot,z-bar-dot)P(?t)=0,where z(t)=x(t)+iy(t), i=?-1, the bar denotes the complex conjugate and -bar is a small positive parameter.The object of this paper is to continue our investigation of this class by studying the stabilization of unstable periodic attractors of system . A feedback control method which is suggested by Pyragas is used to stabilize these unstable periodic attractors. We construct Poincare plots before and after control to prove that the stabilization is achieved. Two examples are presented which served to illustrate this investigation. Maximal Lyapunov exponents and the power spectrum are calculated to show that our periodic attractors are not chaotic attractors

175

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

International Nuclear Information System (INIS)

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

176

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

177

Model reduction of nonlinear systems with external periodic excitations via construction of invariant manifolds  

Science.gov (United States)

A methodology for determining reduced order models of periodically excited nonlinear systems with constant as well as periodic coefficients is presented. The approach is based on the construction of an invariant manifold such that the projected dynamics is governed by a fewer number of ordinary differential equations. Due to the existence of external and parametric periodic excitations, however, the geometry of the manifold varies with time. As a result, the manifold is constructed in terms of temporal and dominant state variables. The governing partial differential equation (PDE) for the manifold is nonlinear and contains time-varying coefficients. An approximate technique to find solution of this PDE using a multivariable Taylor-Fourier series is suggested. It is shown that, in certain cases, it is possible to obtain various reducibility conditions in a closed form. The case of time-periodic systems is handled through the use of Lyapunov-Floquet (L-F) transformation. Application of the L-F transformation produces a dynamically equivalent system in which the linear part of the system is time-invariant; however, the nonlinear terms get multiplied by a truncated Fourier series containing multiple parametric excitation frequencies. This warrants some structural changes in the proposed manifold, but the solution procedure remains the same. Two examples; namely, a 2-dof mass-spring-damper system and an inverted pendulum with periodic loads, are used to illustrate applications of the technique for systems with constant and periodic coefficients, respectively. Results show that the dynamics of these 2-dof systems can be accurately approximated by equivalent 1-dof systems using the proposed methodology.

Gabale, Amit P.; Sinha, S. C.

2011-05-01

178

Reliability modelling for wear out failure period of a single unit system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present paper deals with two time-shifted density models for wear out failure period of a single unit system. The study, considered the time-shifted Gamma and Normal distributions. Wear out failures occur as a result of deterioration processes or mechanical wear and its probability of occurrence increases with time. A failure rate as a function of time deceases in an early failure period and it increases in wear out period. Failure rates for time shifted distributions and expression for m...

Arekar, Kirti; Ailawadi, Satish; Jain, Rinku

2012-01-01

179

The analog channel periodic test of protect system in Qinshan second nuclear power plant  

International Nuclear Information System (INIS)

The thesis introduced the essentiality and principle of the analog channel periodic test of protect system (for short the T1 periodic test hereinafter) in Qinshan Nuclear Power Phase II, including the composing of the T1 test unit, and summarized the trouble during the unit debugging and commercial operation.At the same time,it points out the analysis and solving measures to the trouble. There is positive meaning to lower the risk in later work in nuclear power plant. (authors)

180

Periodic Solution of n-Species Gilpin-Ayala Competition System with Impulsive Perturbations  

Directory of Open Access Journals (Sweden)

Full Text Available The principle aim of this paper is to explore the existence of periodic solution of n-Species Gilpin-Ayala competition system with impulsive perturbations. Sufficient and realistic conditions are obtained by using Mawhin's continuation theorem of the coincidence degree. Further, some numerical simulations show that our model can occur in many forms of complexities including periodic oscillation and chaotic strange attractor.

2013-01-01

 
 
 
 
181

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

182

Stochastic period-doubling bifurcation analysis of a Roessler system with a bounded random parameter  

International Nuclear Information System (INIS)

This paper aims to study the stochastic period-doubling bifurcation of the three-dimensional Roessler system with an arch-like bounded random parameter. First, we transform the stochastic Roessler system into its equivalent deterministic one in the sense of minimal residual error by the Chebyshev polynomial approximation method. Then, we explore the dynamical behaviour of the stochastic Roessler system through its equivalent deterministic system by numerical simulations. The numerical results show that some stochastic period-doubling bifurcation, akin to the conventional one in the deterministic case, may also appear in the stochastic Roessler system. In addition, we also examine the influence of the random parameter intensity on bifurcation phenomena in the stochastic Roessler system. (general)

183

Busy Period Analysis of a Man-machine System Operating Subject To Different Physical Conditions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study deals with some characteristics of a single-unit of a man-machine system operating under different physical conditions. The failure, repair and change of physical conditions (good-poor) are stochastically independent random variables each having an arbitrary distribution. The system analysed by some Markov process technique. The busy period, expected number of visits by the repairman and the cost per unit time in a steady state of the system are obtained. Severa...

Mokaddis, G. S.; Tawfek, M. L.; Elhssia, S. A. M.

2005-01-01

184

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. PMID:25019908

Coclite, A; Gonnella, G; Lamura, A

2014-06-01

185

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

186

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

187

Variation in the orbital period of W UMa-type contact systems  

Science.gov (United States)

The secular variation in the orbital period Porb is studied as a function of the mass ratio q of the components in a sample of 73 contact systems of class W UMa constructed from a survey of current (1991-2003) published photometric and spectroscopic data. Almost all the W UMa-systems (>93% of this sample) are found to have a variation in their orbital periods Porb which alternates in sign independently of their division into A-and Wsubclasses. A statistical study of this sample in terms of the observed characteristics dPorb/dt and q showed that on the average the numbers of increases (35 systems) and decreases (33 systems) in the periods are the same, which indicates the existence of flows directed alternately from one component to the other and illustrates the cyclical character of the thermal oscillations. An analysis of the behavior of dPorb/dt as a function of the mass interval of the primary component yields a more accurate value for the mass ratio, q ? 0.4 ÷ 0.45 at which contact binaries are separated into A-and W-subclasses. No correlations were observed between the fill-out factor for the outer contact configuration, the total mass of the contact system, and the mass ratio of the components, on one hand, and the sign of the secular variation in the period. The physical properties and evolutionary features of these systems are discussed.

Dryomova, G. N.; Svechnikov, M. A.

2006-07-01

188

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

International Nuclear Information System (INIS)

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

189

Frequency domain system identification of helicopter rotor dynamics incorporating models with time periodic coefficients  

Science.gov (United States)

One of the most prominent features of helicopter rotor dynamics in forward flight is the periodic coefficients in the equations of motion introduced by the rotor rotation. The frequency response characteristics of such a linear time periodic system exhibits sideband behavior, which is not the case for linear time invariant systems. Therefore, a frequency domain identification methodology for linear systems with time periodic coefficients was developed, because the linear time invariant theory cannot account for sideband behavior. The modulated complex Fourier series was introduced to eliminate the smearing effect of Fourier series expansions of exponentially modulated periodic signals. A system identification theory was then developed using modulated complex Fourier series expansion. Correlation and spectral density functions were derived using the modulated complex Fourier series expansion for linear time periodic systems. Expressions of the identified harmonic transfer function were then formulated using the spectral density functions both with and without additive noise processes at input and/or output. A procedure was developed to identify parameters of a model to match the frequency response characteristics between measured and estimated harmonic transfer functions by minimizing an objective function defined in terms of the trace of the squared frequency response error matrix. Feasibility was demonstrated by the identification of the harmonic transfer function and parameters for helicopter rigid blade flapping dynamics in forward flight. This technique is envisioned to satisfy the needs of system identification in the rotating frame, especially in the context of individual blade control. The technique was applied to the coupled flap-lag-inflow dynamics of a rigid blade excited by an active pitch link. The linear time periodic technique results were compared with the linear time invariant technique results. Also, the effect of noise processes and initial parameter guess on the identification procedure were investigated. To study the effect of elastic modes, a rigid blade with a trailing edge flap excited by a smart actuator was selected and system parameters were successfully identified, but with some expense of computational storage and time. Conclusively, the linear time periodic technique substantially improved the identified parameter accuracy compared to the linear time invariant technique. Also, the linear time periodic technique was robust to noises and initial guess of parameters. However, an elastic mode of higher frequency relative to the system pumping frequency tends to increase the computer storage requirement and computing time.

Hwang, Sunghwan

1997-08-01

190

Period Changes of BW Vulpeculae: the Influence of Motion in a Binary System  

Science.gov (United States)

This paper presents the reduced photoelectric observational data on the variable star BW Vulpeculae obtained at Timisoara Astronomical Observatory. Using the moments of the observed minima and others from references, we computed a quadratic ephemeris describing a secular evolution. Removing the evolutionary term, from the O-C diagram, it still remains a periodicity. Assuming this due to the light-time effect in a binary system, these residuals allowed us to compute the orbital elements. Finally we concluded that the period variation is described by the superposition of two separate physical effects: the evolution of the pulsating star and the orbital motion in a binary system.

Horvath, Alexandru; Gherega, Octavian; Farkas, Ladislau

191

Stellar rotation--planetary orbit period commensurability in the HAT-P-11 system  

CERN Document Server

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 lightcurve and confirm that their phase with respect to the stellar rotation is mostly stationary for the 48-month timeframe of the observations, confirming the proposed rotation period. For comparison, we apply our methods to Kepler-17 and confirm the findings of Bonomo & Lanza (2012) 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 a...

Béky, Bence; Kipping, David M; Noyes, Robert W

2014-01-01

192

Onset of secular chaos in planetary systems: period doubling and strange attractors  

Science.gov (United States)

As a result of resonance overlap, planetary systems can exhibit chaotic motion. Planetary chaos has been studied extensively in the Hamiltonian framework, however, the presence of chaotic motion in systems where dissipative effects are important, has not been thoroughly investigated. Here, we study the onset of stochastic motion in presence of dissipation, in the context of classical perturbation theory, and show that planetary systems approach chaos via a period-doubling route as dissipation is gradually reduced. Furthermore, we demonstrate that chaotic strange attractors can exist in mildly damped systems. The results presented here are of interest for understanding the early dynamical evolution of chaotic planetary systems, as they may have transitioned to chaos from a quasi-periodic state, dominated by dissipative interactions with the birth nebula.

Batygin, Konstantin; Morbidelli, Alessandro

2011-10-01

193

Onset of Secular Chaos in Planetary Systems: Period Doubling & Strange Attractors  

CERN Document Server

As a result of resonance overlap, planetary systems can exhibit chaotic motion. Planetary chaos has been studied extensively in the Hamiltonian framework, however, the presence of chaotic motion in systems where dissipative effects are important, has not been thoroughly investigated. Here, we study the onset of stochastic motion in presence of dissipation, in the context of classical perturbation theory, and show that planetary systems approach chaos via a period-doubling route as dissipation is gradually reduced. Furthermore, we demonstrate that chaotic strange attractors can exist in mildly damped systems. The results presented here are of interest for understanding the early dynamical evolution of chaotic planetary systems, as they may have transitioned to chaos from a quasi-periodic state, dominated by dissipative interactions with the birth nebula.

Batygin, Konstantin

2011-01-01

194

Water quality in the Gillham Lake-Cossatot River system during dry and wet periods  

Science.gov (United States)

Water samples were collected in the Cossatot River-Gillham Lake system during an extended dry period and after heavy rains to determine the spatial variations in certain water quality characteristics. Of particular interest was the influence of the reservoir discharge on the water quality of the tailwater compared with the effects of four tributaries entering the tailwater below the reservoir. The water quality of the Cossatot River below Gillman Lake at low-flow (dry periods) and during the first 3 days after heavy rainfall (wet period) was influenced more by the tributaries entering the tailwater than by the reservoir water release. We estimated, however, that the amount of particulate inorganic matter released to the tailwater from the reservoir after the initial 3-day wet period would be greater than the amounts entering the tailwater from the tributaries.

Smith, Stephen B.; Moen, Thomas E.

1984-01-01

195

Dispersionless motion and ratchet effect in a square-wave-driven inertial periodic potential system  

Energy Technology Data Exchange (ETDEWEB)

The underdamped Langevin equation of motion of a particle, in a symmetric periodic potential and subjected to a symmetric periodic forcing with mean zero over a period, with nonuniform friction, is solved numerically. The particle is shown to acquire a steady state mean velocity at asymptotically large timescales. At these large timescales the position dispersion grows proportionally with time, t, allowing for calculating the steady state diffusion coefficient D. Interestingly, D shows a peaking behaviour around the same F{sub 0} where the net current peaks. The net (ratchet) current, however, turns out to be largely coherent. At an intermediate timescale, which bridges the small timescale behaviour of dispersion {approx}t{sup 2} to the large time one, the system shows periodic oscillation between dispersionless and steeply growing dispersion depending on the amplitude and frequency of the forcing. The contribution of these different dispersion regimes to ratchet current is analysed.

Saikia, S; Mahato, Mangal C [Department of Physics, North-Eastern Hill University, Shillong 793022 (India)], E-mail: mangal@nehu.ac.in

2009-04-29

196

Dispersionless motion and ratchet effect in a square-wave-driven inertial periodic potential system  

International Nuclear Information System (INIS)

The underdamped Langevin equation of motion of a particle, in a symmetric periodic potential and subjected to a symmetric periodic forcing with mean zero over a period, with nonuniform friction, is solved numerically. The particle is shown to acquire a steady state mean velocity at asymptotically large timescales. At these large timescales the position dispersion grows proportionally with time, t, allowing for calculating the steady state diffusion coefficient D. Interestingly, D shows a peaking behaviour around the same F0 where the net current peaks. The net (ratchet) current, however, turns out to be largely coherent. At an intermediate timescale, which bridges the small timescale behaviour of dispersion ?t2 to the large time one, the system shows periodic oscillation between dispersionless and steeply growing dispersion depending on the amplitude and frequency of the forcing. The contribution of these different dispersion regimes to ratchet current is analysed.

197

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

198

Weak periodic signal detection with the fractional order modified Duffing-Holmes system  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction. The problem of the weak periodic signal detection is very important in the modern radio engineering and communications. The new chaotic systems have been being proposed for the weak signal detection for the last 20 years. The modified Duffing-Holmes system. The modified Duffing-Holmes system detects the weak periodic signals with the minimum signal-to-noise ratio near -91dB. Such result is achieved by means of the system equation with increasing of the equation order. The fractional-order Duffing-Holmes system. The fractional-order Duffing-Holmes systems have been proposed only few years ago. These systems are mostly used in the generation of the fractional chaotic signal which may be used in the secure communications. The modified fractional-order Duffing-Holmes system. In this article the modified fractional-order Duffing-Holmes system is proposed. This system allows increasing the weak-signal sensitivity comparing to the modified Duffing-Holmes system. The proposed weak signal detection system is differed of the modified Duffing-Holmes system by using of the fractional order differential equation instead of the integer order differential equation. Conclusions. The oscillations of the modified fractional order Duffing-Holmes system strongly depend on the fractional order value. As a result the -105dB signal-to-noise ratio for of the weak periodic signals was obtained. The simulation results show that the accurate adjustment of the fractional order leads to the increasing of the detection efficiency.

V. V. Martynyuk

2013-07-01

199

NSVS4484038, a Contact Binary System at the Short-period Cutoff  

Science.gov (United States)

We present a photometric study of the short-period eclipsing binary NSVS4484038. Time-series CCD photometry of the star in the B and V band was carried out. An orbital period of 0.218551 days was determined for the eclipsing binary and a revised linear ephemeris was given. The first photometric solution of the binary system was detected through light-curve synthesis using the Wilson-Devinney method. It reveals an overcontact configuration for the system with a filling-out factor of about 10%. The mass ratio was determined to be 2.74 with an inclination of 72.°1. The less massive secondary component is found to have a higher surface temperature than the primary by about 90 K, indicating that NSVS4484038 could be a contact system of W subtype. The star is then identified to be a new member of W UMa systems at the short-period cutoff. Comparisons with known contact binaries at the short-period cutoff, the properties, and the evolutionary status of the binary system are discussed.

Zhang, X. B.; Deng, L. C.; Wang, K.; Yan, Z. Z.; Tian, J. F.; Peng, Y. J.; Pan, Y.; Luo, Z. Q.; Sun, J. J.; Liu, Q. L.; Xin, H. Q.; Zhou, Q.

2014-09-01

200

Chiral symmetry and bulk-boundary correspondence in periodically driven one-dimensional systems  

Science.gov (United States)

In periodically driven lattice systems, the effective (Floquet) Hamiltonian can be engineered to be topological; then, the principle of bulk-boundary correspondence guarantees the existence of robust edge states. However, such setups can also host edge states not predicted by the Floquet Hamiltonian. The exploration of such edge states and the corresponding unique bulk topological invariants has only recently begun. In this work we calculate these invariants for chiral symmetric periodically driven one-dimensional systems. We find simple closed expressions for these invariants, as winding numbers of blocks of the unitary operator corresponding to a part of the time evolution. This gives a robust way to tune these invariants using sublattice shifts. We illustrate our ideas on the periodically driven Su-Schrieffer-Heeger model, which, as we show, can realize a discrete-time quantum walk; this opens a useful connection between periodically driven lattice systems and discrete-time quantum walks. Our work helps interpret the results of recent simulations where a large number of Floquet Majorana fermions in periodically driven superconductors have been found.

Asbóth, J. K.; Tarasinski, B.; Delplace, P.

2014-09-01

 
 
 
 
201

Control of stochastic resonance in bistable systems by using periodic signals  

International Nuclear Information System (INIS)

According to the characteristic structure of double wells in bistable systems, this paper analyses stochastic fluctuations in the single potential well and probability transitions between the two potential wells and proposes a method of controlling stochastic resonance by using a periodic signal. Results of theoretical analysis and numerical simulation show that the phenomenon of stochastic resonance happens when the time scales of the periodic signal and the noise-induced probability transitions between the two potential wells achieve stochastic synchronization. By adding a bistable system with a controllable periodic signal, fluctuations in the single potential well can be effectively controlled, thus affecting the probability transitions between the two potential wells. In this way, an effective control can be achieved which allows one to either enhance or realize stochastic resonance

202

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

203

Can The Periods of Some Extra-Solar Planetary Systems be Quantized?  

Science.gov (United States)

A simple formula was derived before by Morcos (2013 ), to relate the quantum numbers of planetary systems and their periods. This formula is applicable perfectly for the solar system planets, and some extra-solar planets , of stars of approximately the same masses like the Sun. This formula has been used to estimate the periods of some extra-solar planet of known quantum numbers. The used quantum numbers were calculated previously by other authors. A comparison between the observed and estimated periods, from the given formula has been done. The differences between the observed and calculated periods for the extra-solar systems have been calculated and tabulated. It is found that there is an error of the range of 10% The same formula has been also used to find the quantum numbers, of some known periods, exo-planet. Keywords: Quantization; Periods; Extra-Planetary; Extra-Solar Planet REFERENCES [1] Agnese, A. G. and Festa, R. “Discretization on the Cosmic Scale Inspirred from the Old Quantum Mechanics,” 1998. http://arxiv.org/abs/astro-ph/9807186 [2] Agnese, A. G. and Festa, R. “Discretizing ups-Andro- medae Planetary System,” 1999. http://arxiv.org/abs/astro-ph/9910534. [3] Barnothy, J. M. “The Stability of the Solar Systemand of Small Stellar Systems,” Proceedings of the IAU Sympo-sium 62, Warsaw, 5-8 September 1973, pp. 23-31. [4] Morcos, A.B. , “Confrontation between Quantized Periods of Some Extra-Solar Planetary Systems and Observations”, International Journal of Astronomy and Astrophysics, 2013, 3, 28-32. [5] Nottale, L. “Fractal Space-Time and Microphysics, To-wards a Theory of Scale Relativity,” World Scientific, London, 1994. [6] Nottale , L., “Scale-Relativity and Quantization of Extra- Solar Planetary Systems,” Astronomy & Astrophysics, Vol. 315, 1996, pp. L9-L12 [7] Nottale, L., Schumacher, G. and Gay, J. “Scale-Relativity and Quantization of the Solar Systems,” Astronomy & Astrophysics letters, Vol. 322, 1997, pp. 1018-10 [8]Nottale, L. “Scale-Relativity and Quantization of Exo- planet Orbital Semi-Major Axes,” Astronomy & Astro- physics, Vol. 361, 2000, pp. 379-387.

El Fady Morcos, Abd

204

Binary systems at and beyond the short-period limit of WUMa systems  

Science.gov (United States)

The short-period limit of W UMa-type contact binaries of about 0.22 days is very sharp and well defined. Observations and investigations of close binaries beyond this limit can provide important information on the origin and evolutionary processes of contact binaries, as well as on the formation and migration history of low-mass stars. In the past several years, we have monitored some close binaries below the short-period limit by using several small telescopes and 2m-class telescopes. Photometric solutions and period changes of these binary stars were analyzed and investigated. Some new contact binaries below the limit were detected. Our results reveal that the rarity of contact binaries below the short-period limit could not be explained by rapid dynamical destruction. %

Qian, S.-B.; Jiang, L.-Q.; Zhu, L.-Y.; Zejda, M.; Mikulášek, Z.; Fernández-Lajús, E.; Liu, N.-P.

2014-03-01

205

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)

206

Infinitely many periodic solutions for some second-order differential systems with p(t-Laplacian  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract In this article, we investigate the existence of infinitely many periodic solutions for some nonautonomous second-order differential systems with p(t-Laplacian. Some multiplicity results are obtained using critical point theory. 2000 Mathematics Subject Classification: 34C37; 58E05; 70H05.

Zhang Liang

2011-01-01

207

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

208

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

209

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

CERN Document Server

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

210

Sturm intersection theory for periodic Jacobi matrices and linear Hamiltonian systems  

CERN Document Server

Sturm-Liouville oscillation theory for periodic Jacobi operators with matrix entries is discussed and illustrated. The proof simplifies and clarifies the use of intersection theory of Bott, Maslov and Conley-Zehnder. It is shown that the eigenvalue problem for linear Hamiltonian systems can be dealt with by the same approach.

Schulz-Baldes, Hermann

2011-01-01

211

Two-Well System under Large Amplitude Periodic Forcing: Stochastic Synchronization, Stochastic Resonance and Stability  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study the residence time distributions and explore the possibility of observing stochastic resonance and synchonization of passages in a two-well system driven by a periodic forcing of amplitude larger than a marginal value beyond which one of the two wells become unstable and diasppear. We define and calculate hysteresis loop in the system, the area of which measures the degree of synchronization between the residence time statistics and the input signal, as a function o...

Mahato, Mangal C.; Jayannavar, A. M.

1997-01-01

212

Orbital periods and Accretion disc structure of four AM CVn systems  

CERN Document Server

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

213

Rotating machine vibration signals modelling by a linear and periodically time-varying system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Most of rotating machine vibrations contain possibly modulated periodic components, which are interesting to analyse from the point of view of diagnostic. To this end, a method to estimate sine wave components of frequency fc+m*fd (m in Z) in wide-band noise is elaborated in this article. The originality of this processing comes from the use of a linear and periodically time-varying system. Its input is a sine wave of frequency fc, and its variation is synchronised on the frequency spacing of...

Granjon, Pierre

2001-01-01

214

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

International Nuclear Information System (INIS)

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

215

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 “anomalous” 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

216

Multistability and stable asynchronous periodic oscillations in a multiple-delayed neural system  

Science.gov (United States)

We consider a network of three identical neurons with multiple discrete signal transmission delays. The model for such a network is a system of nonlinear delay differential equations. After some consideration of the absolute synchronization of the system and the global attractivity of the zero solution, we present a detailed discussion about the boundaries of the stability region of the trivial solution. This allows us to determine the possible codimension one bifurcations which occur in the system. In particular, we show the existence of standard Hopf bifurcations giving rise to synchronized periodic solutions and of D3 equivariant Hopf bifurcations giving rise to three types of periodic solutions: phase-locked, mirror-reflecting, and standing waves. Hopf-Hopf and Hopf-steady state bifurcations interactions are shown to exist and give rise to coexistence of stable synchronized and desynchronized solutions. Perturbation techniques coupled with the Floquet theory are used to determine the stability of the phase-locked oscillations.

Campbell, S. A.; Ncube, I.; Wu, J.

2006-02-01

217

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

218

Periodic and chaotic synchronizations of two distinct dynamical systems under sinusoidal constraints  

International Nuclear Information System (INIS)

Highlights: ? Function synchronization of distinct dynamical systems. ? Synchronization onset and vanishing. ? Invariant sets of synchronization. ? Discontinuous dynamical systems. ? Synchronizations of pendulum and Duffing oscillator. - Abstract: In this paper, periodic and chaotic synchronizations between two distinct dynamical systems under specific constraints are investigated from the theory of discontinuous dynamical systems. The analytical conditions for the sinusoidal synchronization of the pendulum and Duffing oscillator were obtained, and the invariant domain of sinusoidal synchronization is achieved. From analytical conditions, the control parameter map is developed. Numerical illustrations for partial and full sinusoidal synchronizations of chaotic and periodic motions of the controlled pendulum with the Duffing oscillator are carried out. This paper presents how to apply the theory of discontinuous dynamical systems to dynamical system synchronization with specific constraints. The function synchronization of two distinct dynamical systems with specific constraints should be identified only by G-functions. The significance of function synchronization of distinct dynamical systems is to make the synchronicity behaviors hidden, which is very useful for telecommunication synchronization and network security.

219

Ultrashort-period MS eclipsing systems. New observations and light curve solutions of six NSVS binaries  

CERN Document Server

We carried out photometric and low-resolution spectral observations of six eclipsing ultrashort-period binaries with MS components. The light curve solutions of the Rozhen observations show that all targets are overcontact systems. We found well-defined empirical relation "period -- semi-major axis" for the short-period binaries and used it for estimation of the global parameters of the targets. Our results revealed that NSVS 925605 is quite interesting target: (a) it is one of a few contact binaries with M components; (b) it exhibits high activity (emission in H$\\alpha$ line, X-ray emission, large cool spots, non-Planck energy distribution); (c) its components differ in temperature by 700 K. All appearances of high magnetic activity and huge fillout factor (0.7) of NSVS 925605 might be assumed as a precursor of the predicted merging of close magnetic binaries. Another unusual binary is NSVS 2700153 which reveals considerable long-term variability.

Dimitrov, Dinko

2015-01-01

220

Effects of time delay on stochastic resonance of a periodically driven linear system with multiplicative and periodically modulated additive white noises  

International Nuclear Information System (INIS)

Stochastic resonance (SR) of a periodically driven time-delayed linear system with multiplicative white noise and periodically modulated additive white noise is investigated. In the condition of small delay time, an approximate analytical expression of output signal-to-noise ratio (SNR) is obtained. The analytical results indicate that (1) there exists a resonance peak in the curve for SNR versus time delay; (2) the time delay will suspend the SR dramatically for SNR versus other parameters of the system, such as noise intensity, correlation intensity, and signal frequency, once a certain value is reached, the SR phenomenon disappears. (general)

 
 
 
 
221

Chaotic attractor in a periodically forced two-phase flow system  

International Nuclear Information System (INIS)

Motivated by the enhancement of heat transfer under oscillating flow conditions in single-phase heated channels and by stability problems in two-phase systems such as those in boiling water reactors, density-wave oscillations have been analyzed by numerically solving the nonlinear, variable delay, functional, ordinary integrodifferential equations that result from integrating the nonlinear partial differential equations for the single- and two-phase heated channel regions along characteristics and along channel length for axially uniform heat fluxes. In the periodic ?P/sub ex/ case (feed pump oscillations) when the system is in the linearly unstable region, it usually evolves asymptotically to one of several different attracting sets, depending on the frequency of ?P/sub ex/: stable period-N limit cycles, stable invariant tori, and a chaotic (or strange) attractor. The nature of the strange attractor was analyzed quantitatively by calculating its correlation dimension - an estimate of its fractal dimension - and the dimension of the phase space in which it can be embedded. These calculations indicate that the strange attractor is indeed a fractal object of fractional dimension 2.048 +- 0.003 and embedding dimension 6. The results of these numerical studies suggest that the heated channel model can operate safely in the linearly unstable region in a dynamically stable mode without excessively large excursions when driven at many frequencies; however, at many other fry frequencies; however, at many other frequencies it cannot. The trajectories that do remain in bounded regions of phase space can be, depending on the forcing frequency, periodic with a short or very long period, very near periodic, or completely aperiodic or chaotic. Hence, it is possible to enhance heat transfer while maintaining safety in two-phase flow systems by operating them in an oscillatory mode

222

Dynamics of a two-degree-of freedom periodically-forced system with a rigid stop: Diversity and evolution of periodic-impact motions  

Science.gov (United States)

A two-degree-of-freedom periodically-forced system with a clearance is considered. The correlation between dynamic performance and system parameters is studied to find their feasible matching law. The fundamental group of impact motions is defined, which have the excitation period and differ by the number p of impacts. The generation mechanism of complete and incomplete chattering-impact vibration of the system is studied. A series of singular points between any two adjacent fundamental impact motions are found, at which real-grazing and bare-grazing bifurcation boundaries of one of them, saddle-node and period-doubling bifurcation boundaries of the other alternately intersect and create two types of transition regions: hysteresis and tongue-shaped regions. Subharmonic impact motions are found to regularly appear in the tongue-shaped regions. Based on the sampling ranges of parameters, dynamics of the system is studied with emphasis on the influence of system parameters on impact velocities, existence regions and correlative distribution of single-impact periodic motions by multi-parameter and multi-performance co-simulation analysis.

Luo, G. W.; Zhu, X. F.; Shi, Y. Q.

2015-01-01

223

Stabilization of unstable periodic attractors of complex damped non-linear dynamical systems  

Energy Technology Data Exchange (ETDEWEB)

In the recent paper [Int. J. Non-Linear Mech. 35 (2000) 309], periodic attractors were studied for a class of complex damped non-linear dynamical systems of the form:z-double dot+{omega}{sup 2}z+{epsilon}z-dotf(z,z-bar,z-dot,z-bar-dot)P({omega}t)=0,where z(t)=x(t)+iy(t), i={radical}-1, the bar denotes the complex conjugate and -bar is a small positive parameter.The object of this paper is to continue our investigation of this class by studying the stabilization of unstable periodic attractors of system . A feedback control method which is suggested by Pyragas is used to stabilize these unstable periodic attractors. We construct Poincare plots before and after control to prove that the stabilization is achieved. Two examples are presented which served to illustrate this investigation. Maximal Lyapunov exponents and the power spectrum are calculated to show that our periodic attractors are not chaotic attracto0008.

Mahmoud, G.M.; Farghaly, A.A.M

2003-07-01

224

Periodic Surveillance Testing Improvement Approach for the Digital Plant Protection System  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-10-15

225

Periodic Surveillance Testing Improvement Approach for the Digital Plant Protection System  

International Nuclear Information System (INIS)

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

226

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

227

Stripe systems with competing interactions on quasi-one dimensional periodic substrates.  

Science.gov (United States)

We numerically examine the two-dimensional ordering of a stripe forming system of particles with competing long-range repulsion and short-range attraction in the presence of a quasi-one-dimensional corrugated substrate. As a function of increasing substrate strength or period we show that a remarkable variety of distinct orderings can be realized, including modulated stripes, prolate clump phases, two dimensional ordered kink structures, crystalline void phases, and smectic phases. Additionally in some cases the stripes align perpendicular to the substrate troughs. Our results suggest that a new route to self assembly for systems with competing interactions can be achieved through the addition of a simple periodic modulated substrate. PMID:25030212

McDermott, Danielle; Olson Reichhardt, Cynthia J; Reichhardt, Charles

2014-09-01

228

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)

229

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

230

Notes on Multiple Periodic Solutions for Second-order Discrete Hamiltonian System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

By a new orthogonal direct sum decomposition $E_{M} = Y \\oplus Z$, which $Z$ is related to $\\Delta u_i(i=1,2,3,....,M)$, and a new functional $I(u)$, the method in [2] is improved to obtain new multiple periodic solutions with negativity hypothesis on $F$ for a second-order discrete Hamiltonian system. Moreover, we exhibit an instructive example to make our result more clear, which hasn't been solved by the known results.

Ding, Liang; Wei, Jinlong

2014-01-01

231

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The objective of the present study is the design of log periodic ring printed antennas array witch generates circular polarization with wide band by single feed linearly polarized elements for GPS systems. The radiating elements have been fed by magnetic coupling through a slot. The circular polarization is achieved by having a basic 2×2 sub-arrays with unique element angular and phase arrangement, both the element angular orientation and feed phase are arranged in the 0°, 90°, 180 and 270...

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

2012-01-01

232

Diffusive mixing of periodic wave trains in reaction-diffusion systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We consider reaction-diffusion systems on the infinite line that exhibit a family of spectrally stable spatially periodic wave trains $u_0(kx-\\om t;k)$ that are parameterized by the wave number $k$. We prove stable diffusive mixing of the asymptotic states $u_0(k x+\\phi_{\\pm};k)$ as $x\\ra \\pm\\infty$ with different phases $\\phi_-\

Sandstede, Bjo?rn; Scheel, Arnd; Schneider, Guido; Uecker, Hannes

2011-01-01

233

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

234

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

International Nuclear Information System (INIS)

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

235

Periodical gait asymmetry assessment using real-time wireless gyroscopes gait monitoring system.  

Science.gov (United States)

A real-time gait monitoring system that incorporates an immediate and periodical assessment of gait asymmetry is described. This system was designed for gait analysis and rehabilitation of patients with pathologic gait. It employs wireless gyroscopes to measure the angular rate of the thigh and shank in real time. Cross-correlation of the lower extremity (Cc(norm)), and normalized Symmetry Index (SI(norm)) are implemented as new approaches to periodically determine the gait asymmetry in each gait cycle. Cc(norm) evaluates the signal patterns measured by wireless gyroscopes in each gait cycle. SI(norm) determines the movement differences between the left and right limb. An experimental study was conducted to examine the viability of these methods. Artificial asymmetrical gait was simulated by placing a load on one side of the limbs. Results showed that there were significant differences between the normal gait and asymmetrical gait (p < 0.01). They also indicated that the system worked well in periodically assessing the gait asymmetry. PMID:22074136

Gouwanda, D; Senanayake, S M N A

2011-11-01

236

On stability zones for discrete-time periodic linear Hamiltonian systems  

Directory of Open Access Journals (Sweden)

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

2006-01-01

237

On stability zones for discrete-time periodic linear Hamiltonian systems  

Directory of Open Access Journals (Sweden)

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

R?svan Vladimir

2006-01-01

238

On the structure of the set of bifurcation points of periodic solutions for multiparameter Hamiltonian systems  

International Nuclear Information System (INIS)

This paper deals with periodic solutions of the Hamilton equation x-dot (t)=J?x H(x(t),?), where H element of C2,0(R2n×Rk,R) and ? element of Rk is a parameter. Theorems on global bifurcation of solutions with periods (2?)/j, j element of N, from a stationary point (x0,?0) element of R2n×Rk are proved. ?x2 H(x0,?0) can be singular. However, it is assumed that the local topological degree of ?xH(·, ?0) at x0 is nonzero. For systems satisfying ?xH(x0, ?) = 0 for all ? element of Rk it is shown that (global) bifurcation points of solutions with periods (2?)/j can be identified with zeros of appropriate continuous functions Fj:Rk?R. If, for all ? element of Rk, ?x2H(x0,?)=diag(A(?),B(?)), where A(?) and B(?) are (n × n)-matrices, then Fj can be defined by Fj(?) = det[A(?)B(?) ? j2I]. Symmetry breaking results concerning bifurcation of solutions with different minimal periods are obtained. A geometric description of the set of bifurcation points is given. Examples of constructive application of the theorems proved to analytical and numerical investigation and visualization of the set of all bifurcation points in given domain are provided. This paper is based on a part of the author's thesis (Radzki 2005 Branching points of periodic solutions of autonomous Hamiltonian systems (Polish) PhD Thesis Nicolaus Copernicus University, Faculty of Mathematics and Computer Science, Toru?)

239

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)

240

Magnet power supply control system for CSRm super-long-period slow extraction  

International Nuclear Information System (INIS)

In order to realize the HIRFL-CSR super-long-period slow extraction, the distributed control system of the CSR main ring (CSRm) power supply is designed based on high-speed ethernet, with the controller of the power supply employing ARM + DSP architecture. The control cycle adopts multipart handling mechanism to solve the problem that the waveform data is too large to be stored in the controller. The control system has been tested in the HIRFL-CSR, and successfully conducted the carbon ion's ten-thousand-second slow extraction. (authors)

 
 
 
 
241

Accurate frequency domain measurement of the best linear time-invariant approximation of linear time-periodic systems including the quantification of the time-periodic distortions  

Science.gov (United States)

Time-periodic (TP) phenomena occurring, for instance, in wind turbines, helicopters, anisotropic shaft-bearing systems, and cardiovascular/respiratory systems, are often not addressed when classical frequency response function (FRF) measurements are performed. As the traditional FRF concept is based on the linear time-invariant (LTI) system theory, it is only approximately valid for systems with varying dynamics. Accordingly, the quantification of any deviation from this ideal LTI framework is more than welcome. The “measure of deviation” allows us to define the notion of the best LTI (BLTI) approximation, which yields the best - in mean square sense - LTI description of a linear time-periodic LTP system. By taking into consideration the TP effects, it is shown in this paper that the variability of the BLTI measurement can be reduced significantly compared with that of classical FRF estimators. From a single experiment, the proposed identification methods can handle (non-)linear time-periodic [(N)LTP] systems in open-loop with a quantification of (i) the noise and/or the NL distortions, (ii) the TP distortions and (iii) the transient (leakage) errors. Besides, a geometrical interpretation of the BLTI approximation is provided, leading to a framework called vector FRF analysis. The theory presented is supported by numerical simulations as well as real measurements mimicking the well-known mechanical Mathieu oscillator.

Louarroudi, E.; Pintelon, R.; Lataire, J.

2014-10-01

242

Linear response as a singular limit for a periodically driven closed quantum system  

International Nuclear Information System (INIS)

We address the issue of the validity of linear response theory for a closed quantum system subject to a periodic external driving. Linear response theory (LRT) predicts energy absorption at frequencies of the external driving where the imaginary part of the appropriate response function is different from zero. Here we show that, for a fairly general nonlinear many-body system on a lattice subject to an extensive perturbation, this approximation should be expected to be valid only up to a time t* depending on the strength of the driving, beyond which the true coherent Schrödinger evolution departs from the linear response prediction and the system stops absorbing energy from the driving. We exemplify this phenomenon in detail with the example of a quantum Ising chain subject to a time-periodic modulation of the transverse field, by comparing an exact Floquet analysis with the standard results of LRT. In this context, we also show that if the perturbation is just local, the system is expected in the thermodynamic limit to keep absorbing energy, and LRT works at all times. We finally argue more generally the validity of the scenario presented for closed quantum many-body lattice systems with a bound on the energy-per-site spectrum, discussing the experimental relevance of our findings in the context of cold atoms in optical lattices and ultra-fast spectroscopy experiments. (paper)

243

Evaluation of raw milk quality in different production systems and periods of the year  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The objective of this study was to evaluate the quality of raw milk in different production systems and its variation throughout the year. The data were collected from 943 dairy farms in the South, Central-West and Central regions of the state of Minas Gerais, and in Vale do Paraíba, in the state of [...] São Paulo, Brazil. The data were collected in the period from January 2009 to September 2011, in a total of 18,206 samples. The properties were divided into confinement, semi-confinement and extensive production systems. The evaluated factors were somatic cell count (SCC), total bacterial count (TBC) and protein and fat contents. There was no effect of production system on the contents of protein, fat and SCC. Total bacterial count, however, was affected by production. Seasonal variations were found for SCC, TBC, protein and fat; the highest protein values were found from March to June; the highest fat contents were obtained from May to August; and TBC and SCC, from December to March. The production system does not interfere with the percentage of fat and protein and SCC of the milk. However, confinement systems present a better TBC content. Both month and year are factors that interfere with TBC, SCC, protein and milk fat, and the best patterns are found in the coldest periods of the year.

Marcos Inácio, Marcondes; Daniele Canabrava, Jácome; Alex Lopes da, Silva; Luciana Navajas, Rennó; Ana Clarissa dos Santos, Pires.

2014-12-01

244

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

245

A Multiple Period Problem in Distributed Energy Management Systems Considering CO2 Emissions  

Science.gov (United States)

Consider a special district (group) which is composed of multiple companies (agents), and where each agent responds to an energy demand and has a CO2 emission allowance imposed. A distributed energy management system (DEMS) optimizes energy consumption of a group through energy trading in the group. In this paper, we extended the energy distribution decision and optimal planning problem in DEMSs from a single period problem to a multiple periods one. The extension enabled us to consider more realistic constraints such as demand patterns, the start-up cost, and minimum running/outage times of equipment. At first, we extended the market-oriented programming (MOP) method for deciding energy distribution to the multiple periods problem. The bidding strategy of each agent is formulated by a 0-1 mixed non-linear programming problem. Secondly, we proposed decomposing the problem into a set of single period problems in order to solve it faster. In order to decompose the problem, we proposed a CO2 emission allowance distribution method, called an EP method. We confirmed that the proposed method was able to produce solutions whose group costs were close to lower-bound group costs by computational experiments. In addition, we verified that reduction in computational time was achieved without losing the quality of solutions by using the EP method.

Muroda, Yuki; Miyamoto, Toshiyuki; Mori, Kazuyuki; Kitamura, Shoichi; Yamamoto, Takaya

246

Computer aided periodical and regulated service tests on radiation measuring systems  

International Nuclear Information System (INIS)

Measuring systems for radioactive radiation, which must be registered by official order, have to be tested periodically according to laid down rules (WKP). A strategy for a test-device was drawn up for a flexible adaption of the procedure to individual requests, but also for a standardization of the logical interface to the measuring system. Especially the interaction of testing and normal measuring procedures is clearly defined and transparent; the original functional parts of the measuring run are used during the test as far as possible. Adapation to individual requirements is controlled by ASCII-Files, so that the program code remains unchanged. The functional possibilities are extensive also for the inspections by customers and authorities. Due to the nearly automatical run of the procedure, including printout of the results, the tests are always comparable. The standard was checked by some actual projects, basede on SYSTEM 7000 (Thermo Instrument Systems GmbH) and PC runing under DOS. (orig.)

247

Stabilizing chaotic system on periodic orbits using multi-interval and modern optimal control strategies  

Science.gov (United States)

In this paper, optimal approaches for controlling chaos is studied. The unstable periodic orbits (UPOs) of chaotic system are selected as desired trajectories, which the optimal control strategy should keep the system states on it. Classical gradient-based optimal control methods as well as modern optimization algorithm Particle Swarm Optimization (PSO) are utilized to force the chaotic system to follow the desired UPOs. For better performance, gradient-based is applied in multi-intervals and the results are promising. The Duffing system is selected for examining the proposed approaches. Multi-interval gradient-based approach can put the states on UPOs very fast and keep tracking UPOs with negligible control effort. The maximum control in PSO method is also low. However, due to its inherent random behavior, its control signal is oscillatory.

Abedini, Mohammad; Vatankhah, Ramin; Assadian, Nima

2012-10-01

248

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)

249

Resonant motions in the presence of degeneracies for quasi-periodically perturbed systems  

CERN Document Server

We consider one-dimensional systems in the presence of a quasi-periodic perturbation, in the analytical setting, and study the problem of existence of quasi-periodic solutions which are resonant with the frequency vector of the perturbation. We assume that the unperturbed system is locally integrable and anisochronous, and that the frequency vector of the perturbation satisfies the Bryuno condition. Existence of resonant solutions is related to the zeroes of a suitable function, called the Melnikov function - by analogy with the periodic case. We show that, if the Melnikov function has a zero of odd order and under some further condition on the sign of the perturbation parameter, then there exists at least one resonant solution which continues an unperturbed solution. If the Melnikov function is identically zero then one can push perturbation theory up to the order where a counterpart of Melnikov function appears and does not vanish identically: if such a function has a zero of odd order and a suitable positi...

Corsi, Livia

2012-01-01

250

Detection of a Cyclic Period Change in the W UMa-Type System HT Virginis  

Science.gov (United States)

HT Vir is a well-known quadruple system with three components visible in the spectra. However, the cyclic variation of the O - C diagram has not been presented until now. To search for a variation in the O - C diagram of HT Vir, we monitored it from 2007 March to 2009 February, and as a result, 7 times of light minimum were obtained. Also, 3 times of light minimum were determined by us with photoelectric data obtained at Mt. Suhora observatory by using three channel photometers attached on the 60-cm Cassegrain telescope (Zola et al. 2005). Based on 56 times of light minimum, we report the discovery of a cyclic variation in the orbital period of HT Vir. It was found that the orbital period of the binary shows a 30.5 yr cyclic change with a semiamplitude of 0.0066 d. The period variation may be caused by a disturbance of component A to the contact system orbit. More times of light minimum with high precision are needed to check the nature of the O - C plot in the future.

Liao, Wen-Ping; Qian, Sheng-Bang

2010-06-01

251

1/1 resonant periodic orbits in three dimensional planetary systems  

CERN Document Server

We study the dynamics of a two-planet system, which evolves being in a $1/1$ mean motion resonance (co-orbital motion) with non-zero mutual inclination. In particular, we examine the existence of bifurcations of periodic orbits from the planar to the spatial case. We find that such bifurcations exist only for planetary mass ratios $\\rho=\\frac{m_2}{m_1}<0.0205$. For $\\rho$ in the interval $0<\\rho<0.0205$, we compute the generated families of spatial periodic orbits and their linear stability. These spatial families form bridges, which start and end at the same planar family. Along them the mutual planetary inclination varies. We construct maps of dynamical stability and show the existence of regions of regular orbits in phase space.

Antoniadou, Kyriaki I; Varvoglis, Harry

2014-01-01

252

The BVRI Light Curves And Period Analysis Of The Beta Lyrae System XX Leonis  

CERN Document Server

The contact eclipsing binary system XX Leonis (P = 0.97 days, sp A8) has been analysed using the PHOEBE programme, based on the Wilson Devinney code. The BVRI light curves were obtained during spring 2006 using the 20-cm telescope and ST-7 CCD detector. The effective temperature of the primary component determined from the photometric analysis is T=(7889+/-61)K, the inclination of the orbit is i=(89.98+/-2.45)deg and the photometric mass ratio q=(0.41+/-0.01). Also the third body hypothesis was suggested, based on the period analysis using 57 minimum times and resulting the period of the third body p3= (52.96+/-0.01)yr, amplitude A=(0.057+/-0.029)d and eccentricity e=(0.79+/-0.08) which gives the minimum mass m3,min=(3.6+/-0.8)M_sun.

Zasche, P; Svoboda, P

2007-01-01

253

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

Science.gov (United States)

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

Lindbo, Dag; Tornberg, Anna-Karin

2012-04-01

254

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

CERN Document Server

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

Lindbo, Dag

2011-01-01

255

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

Directory of Open Access Journals (Sweden)

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

Mohsen Timoumi

2011-07-01

256

Health care system of the Republic of Serbia in the period 2004-2012  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction. The backbone of Serbian health system forms the public healthcare provider network with 355 institutions and around 112,000 employees, owned and controlled by the Ministry of Health and financed mainly by the Republican Health Insurance Fund. The law recognizes private practice that was not included, till recently, in the public funding scheme. New Health Insurance Law (2005 decreased the number of entitlements in the basic health service package. It abolished the right to dental health care for adults (exceptions are: children, older than 65, pregnant women and emergency cases as well as the right to compensate travel expenses. The aim of this study was to evaluate the effects of health care system of the Republic of Serbia and indicate parameters that determine the state of health of the population, on the ground of data obtained by the Institute of Public Health of Serbia. Results. In the period 2004-2012, cardiovascular diseases represented the main cause of illness in Serbia (50%. In 2012 digestive system diseases were on the second place. Neoplasm and nervous system diseases were on the third place. From 2007 to 2012 there was slight decline in the birth rate and number of deaths, but the death rate increased from 13.9 to 14.2. Health care system in Serbia is funded through the combination of public finances and private contributions. Primary care is provided in 158 health care centres and health care stations, secondary and tertiary care services are offered in general hospitals, specialized hospitals, clinics, clinico-hospital centers and clinical centres. Conclusion. A significant but not satisfactory progress has been achieved in the field of health status indicators as the most important outcome of the final performance of the health system. The transition of public health care system in Serbia since the communist period to present and slow integration with European Union is unfinished process.

Gaji?-Stevanovi? Milena

2014-01-01

257

Tracking unstable steady states and periodic orbits of oscillatory and chaotic electrochemical systems using delayed feedback control.  

Science.gov (United States)

Experimental results are presented on successful application of delayed-feedback control algorithms for tracking unstable steady states and periodic orbits of electrochemical dissolution systems. Time-delay autosynchronization and delay optimization with a descent gradient method were applied for stationary states and periodic orbits, respectively. These tracking algorithms are utilized in constructing experimental bifurcation diagrams of the studied electrochemical systems in which Hopf, saddle-node, saddle-loop, and period-doubling bifurcations take place. PMID:17014214

Kiss, István Z; Kazsu, Zoltán; Gáspár, Vilmos

2006-09-01

258

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 t...

Vyatkin V. B.

2013-01-01

259

Periodic solution for a delayed three-species food-chain system with Holling type-II functional response  

Directory of Open Access Journals (Sweden)

Full Text Available A delayed three-species periodic food-chain system with Holling type-II functional response is investigated. By using Gaines and Mawhin's continuation theorem of coincidence degree theory, a set of easily verifiable sufficient conditions is derived for the existence of positive periodic solutions to the system.

Rui Xu

2003-11-01

260

Periodic solution for a delayed three-species food-chain system with Holling type-II functional response  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A delayed three-species periodic food-chain system with Holling type-II functional response is investigated. By using Gaines and Mawhin's continuation theorem of coincidence degree theory, a set of easily verifiable sufficient conditions is derived for the existence of positive periodic solutions to the system.

Rui Xu; Qiming Liu

2003-01-01

 
 
 
 
261

Spectra and gap amplification for systems with two widely different incommensurate periodicities  

International Nuclear Information System (INIS)

We derive analytically the spectrum for the Schroedinger equation for quasiperiodic systems with two length scales: one large ''macroscopic'' scale [e.g., a cos(2?x/lambda)] and one small ''microscopic'' scale [e.g., v cos(2?x)]. The phase diagram includes regimes with exponentially narrow gaps due to the slowly varying potential, regimes where the rapidly varying potential amplifies these narrow gaps, and regimes with exponentially narrow ''Landau bands.'' The full ''devil's-staircase'' spectrum with gaps at wave vectors q = m?+n?/lambda develops in a hierarchical manner as a increases. The results apply to systems with superlattices, to celestial orbits with two periodic perturbations, to systems with slowly varying lattice distortions, and, in particular, to quasi-one-dimensional magnets such as bis(tetramethyltetraselenafulvalene) perchlorate [(TMTSF)2ClO4] in magnetic fields, where our findings may provide insight into the experimentally observed cascade of phase transitions

262

Resonance tongues and patterns in periodically forced reaction-diffusion systems  

CERN Document Server

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

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

2004-01-01

263

Tunneling Dynamics of Dipolar Bosonic System with Periodically Modulated s-wave Scattering  

Science.gov (United States)

Within the mean-field three-site Bose—Hubbard model, the tunneling dynamics of dipolar bosonic gas with a periodically modulation of s-wave scattering is investigated. The system experiences complex and rich coherent tunneling (CT)-coherent destruction of tunneling (CDT) transitions resulting from the correlated effect among the next-neighbor dipole-dipole interaction, the on-site interaction and the modulated s-wave scattering. In particular, The region of the modulated s-wave scattering for generating CT (CDT) is the widest (narrowest) when the on-site interaction and the next-neighbor dipole-dipole interaction have some correlated values, which are closely related to the tunneling energy and the interaction energy of the system. The correlated values for appearing CDT can be theoretically gained from the tunneling energy and the interaction energy of the system.

Yu, Zi-Fa; Xue, Ju-Kui

2014-05-01

264

Effect of periodic surface cracks on the interfacial fracture of thermal barrier coating system  

Science.gov (United States)

Periodic surface cracks and interfacial debonding in thermal barrier coating (TBC) system may be induced during cooling process. The objective of this work is to investigate the effect of periodic surface cracks on the interfacial fracture of TBC system. The finite element method (FEM) incorporating cohesive zone model is used in analysis. It is found that surface crack spacing has significant effect on the initiation and propagation of short interface crack. Three different regions are identified for describing the effect of surface crack spacing. In Region I the interface crack driving force is dramatically reduced due to high surface crack density. In this case, the initiation of interfacial delamination can be delayed. Region II applies as the surface crack spacing is moderate. Analysis of this transition zone brings to the definition of normalized critical surface crack spacing. Region III arises for sufficient large surface crack spacing. In this case, the interface crack driving force reaches a steady state, where the effects of adjacent surface cracks are relatively insignificant and can be ignored. It can be concluded that an appropriately high surface crack density can enhance the durability of TBC system.

Fan, X. L.; Xu, R.; Zhang, W. X.; Wang, T. J.

2012-10-01

265

Design of tapered arm impulse radiating antenna with log periodic lens system for skin cancer treatment.  

Science.gov (United States)

A Prolate-Spheroidal Impulse Radiating Antenna (PSIRA) is used as a non-invasive technique for generating an electromagnetic implosion to kill melanoma cells. It can launch and focus fast (100?ps) high voltage (>50?KV) pulses into the biological targets. It can be used to obtain electromagnetic focusing on the target to reduce the damage to the tissue layers surrounding the target (skin). The main aim of this work is to improve the gain of the antenna, enhance the electric field intensity and to reduce the spot size at the focal point. In this work the PSIRA with tapered arm is designed to increase the gain of the antenna. The log periodic lens system is designed to enhance the electric field and reduce the spot size. The IRA with tapered arms located at the position of ??=?60° gives a gain improvement of 14.28% when compared to a traditional IRA. In this work a 10-layer dielectric lens system is designed to match the 100?ps pulses to the skin phantom. Simulation results show that the electric field is increased by a factor of 2. The spot size is reduced from 1?cm to 0.75?cm at the focal point where the target is placed. The proposed Log periodic lens system provides an increase in electric field amplitude and reduction in spot size. PMID:24548051

Petrishia, A; Sasikala, M

2014-04-01

266

Soliton defects in one-gap periodic system and exotic supersymmetry  

Science.gov (United States)

By applying Darboux-Crum transformations to the quantum one-gap Lamé system, we introduce an arbitrary countable number of bound states into forbidden bands. The perturbed potentials are reflectionless and contain two types of soliton defects in the periodic background. The bound states with a finite number of nodes are supported in the lower forbidden band by the periodicity defects of the potential well type, while the pulse-type bound states in the gap have an infinite number of nodes and are trapped by defects of the compression modulations nature. We investigate the exotic nonlinear N =4 supersymmetric structure in such paired Schrödinger systems, which extends an ordinary N =2 supersymmetry and involves two bosonic generators composed from Lax-Novikov integrals of the subsystems. One of the bosonic integrals has a nature of a central charge and allows us to liaise the obtained systems with the stationary equations of the Korteweg-de Vries and modified Korteweg-de Vries hierarchies. This exotic supersymmetry opens the way for the construction of self-consistent condensates based on the Bogoliubov-de Gennes equations and associated with them new solutions to the Gross-Neveu model. They correspond to the kink or kink-antikink defects of the crystalline background in dependence on whether the exotic supersymmetry is unbroken or spontaneously broken.

Arancibia, Adrián; Correa, Francisco; Jakubský, Vít; Mateos Guilarte, Juan; Plyushchay, Mikhail S.

2014-12-01

267

Soliton defects in one-gap periodic system and exotic supersymmetry  

CERN Document Server

By applying Darboux-Crum transformations to the quantum one-gap Lame system, we introduce an arbitrary countable number of bound states into forbidden bands. The perturbed potentials are reflectionless and contain two types of soliton defects in the periodic background. The bound states with finite number of nodes are supported in the lower forbidden band by the periodicity defects of the potential well type, while the pulse type bound states in the gap have infinite number of nodes and are trapped by defects of the compression modulations nature. We investigate the exotic nonlinear N=4 supersymmetric structure in such paired Schrodinger systems, which extends an ordinary N=2 supersymmetry and involves two bosonic generators composed from Lax-Novikov integrals of the subsystems. One of the bosonic integrals has a nature of a central charge, and allows us to liaise the obtained systems with the stationary equations of the Korteweg-de Vries and modified Korteweg-de Vries hierarchies. This exotic supersymmetry o...

Arancibia, Adrian; Jakubsky, Vit; Guilarte, Juan Mateos; Plyushchay, Mikhail S

2014-01-01

268

The short-period low-mass binary system CC Com revisited  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study we determined precise orbital and physical parameters of the very short period low-mass contact binary system CC Com. The parameters are obtained by analysis of the new CCD data with the archival spectroscopic data. The physical parameters of the components derived as $M_\\textrm{c}$ = 0.717(14) $M_{\\odot}$, $M_\\textrm{h}$ = 0.378(8) $M_{\\odot}$, $R_\\textrm{c}$ = 0.708(12) $R_{\\odot}$, $R_\\textrm{h}$ = 0.530(10) $R_{\\odot}$, $L_\\textrm{c}$ = 0.138(12) $L_{\\odot}...

Kose, O.; Kalomeni, B.; Keskin, V.; Ulas, B.; Yakut, K.

2011-01-01

269

Interventions to safeguard system effectiveness during periods of emergency department crowding.  

Science.gov (United States)

This article summarizes the proceedings of a breakout session, "Interventions to Safeguard System Effectiveness," at the 2011 Academic Emergency Medicine consensus conference, "Interventions to Assure Quality in the Crowded Emergency Department." Key definitions fundamental to understanding the effectiveness of emergency care during periods of emergency department (ED) crowding are outlined. Next, a proposed research agenda to evaluate interventions directed at improving emergency care effectiveness is outlined, and the paper concludes with a prioritization of those interventions based on breakout session participant discussion and evaluation. PMID:22168196

Kocher, Keith E; Shane, Steven A; Venkatesh, Arjun K; Aronsky, Dominik; Asplin, Brent R; Rathlev, Niels K

2011-12-01

270

Possibility of the Solid-Fluid Transition in Moving Periodic Systems  

CERN Document Server

The steady sliding state of periodic structures such as charge density waves and flux line lattices is numerically studied based on two and three dimensional driven random field XY models. We focus on the dynamical phase transition between plastic flow and moving solid phases controlled by the magnitude of the driving force. By analyzing the connectivity of co-moving clusters, we find that they percolate the system within a finite observation time under driving forces larger than a certain critical force. The critical force, however, logarithmically diverges with the observation time, i.e. the moving solid phase exhibits only within a certain finite time, which exponentially grows with the driving force.

Nogawa, T; Matsukawa, H; Nogawa, Tomoaki; Yoshino, Hajime; Matsukawa, Hiroshi

2005-01-01

271

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

Directory of Open Access Journals (Sweden)

Full Text Available Respiratory viruses cause disease in humans characterized by an abrupt onset of symptoms. Studies in humans and animal models have shown that symptoms are not immediate and appear days or even weeks after infection. Since the initial symptoms are a manifestation of virus recognition by elements of the innate immune response, early virus replication must go largely undetected. The interval between infection and the emergence of symptoms is called the incubation period and is widely used as a clinical score. While incubation periods have been described for many virus infections the underlying mechanism for this asymptomatic phase has not been comprehensively documented. Here we review studies of the interaction between human pathogenic respiratory RNA viruses and the host with a particular emphasis on the mechanisms used by viruses to inhibit immunity. We discuss the concept of the “stealth phase”, defined as the time between infection and the earliest detectable inflammatory response. We propose that the “stealth phase” phenomenon is primarily responsible for the suppression of symptoms during the incubation period and results from viral antagonism that inhibits major pathways of the innate immune system allowing an extended time of unhindered virus replication.

Thomas M. Moran

2010-11-01

272

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

Science.gov (United States)

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?, 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 Teff = 4960 K, log g = 3.3, [Fe/H] = 0.09 and ? = 1.5 km s-1. 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, Nd) elements. We conclude that IP Eri abundances agree with those of normal field stars of the same metallicity. The long period and non-null eccentricity indicate that this system cannot be the end product of a common-envelope phase; it calls instead for another less catastrophic binary-evolution channel presented in detail in a companion paper. Appendix A is available in electronic form at http://www.aanda.orgHERMES spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A30

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

2014-07-01

273

Precise alignment of laser and electron beams in a periodic focusing system for multiple Compton backscattering  

International Nuclear Information System (INIS)

In the present paper, methods of precise alignment of laser and electron beams in a periodic focusing system for generating intense ?-rays by multiple Compton backscattering are discussed. In the system, a CO2 laser beam and a 5.8 GeV electron beam are focused by a series of optical lenses and permanent quadrupole magnets, respectively. Since the beam sizes are as small as 20-50 ?m at 120 collision points, a precise alignment within about 3 ?m is required. The electron beam can be aligned by the energy-scanned beam-based method, but this method is not appropriate for the laser beam since the wavelength is not changed easily. Instead, a new method of normal reflection using Michelson interferometers is considered. Diffraction analysis shows that the misalignment of lenses can be corrected by reducing the integrated intensity of the laser beam at the detector of the interferometer, which decreases monotonically with the reduction of alignment errors

274

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

CERN Document Server

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

275

Numerical continuation of families of heteroclinic connections between periodic orbits in a Hamiltonian system  

International Nuclear Information System (INIS)

This paper is devoted to the numerical computation and continuation of families of heteroclinic connections between hyperbolic periodic orbits (POs) of a Hamiltonian system. We describe a method that requires the numerical continuation of a nonlinear system that involves the initial conditions of the two POs, the linear approximations of the corresponding manifolds and a point in a given Poincaré section where the unstable and stable manifolds match. The method is applied to compute families of heteroclinic orbits between planar Lyapunov POs around the collinear equilibrium points of the restricted three-body problem in different scenarios. In one of them, for the Sun–Jupiter mass parameter, we provide energy ranges for which the transition between different resonances is possible. (paper)

276

Controlling chaos to unstable periodic orbits and equilibrium state solutions for the coupled dynamos system  

International Nuclear Information System (INIS)

In the case where the knowledge of goal states is not known, the controllers are constructed to stabilize unstable steady states for a coupled dynamos system. A delayed feedback control technique is used to suppress chaos to unstable focuses and unstable periodic orbits. To overcome the topological limitation that the saddle-type steady state cannot be stabilized, an adaptive control based on LaSalle's invariance principle is used to control chaos to unstable equilibrium (i.e. saddle point, focus, node, etc.). The control technique does not require any computer analysis of the system dynamics, and it operates without needing to know any explicit knowledge of the desired steady-state position. (general)

277

Non-linear space-periodic dynamo in an ABC-forced magnetohydrodynamic system  

CERN Document Server

Non-linear behavior of an MHD system with ABC forcing under periodic boundary conditions is considered. Most computations are performed for a fixed kinematic Reynolds number and magnetic Reynolds numbers increasing from 0 to 60. The kinematic Reynolds number is small enough for the trivial solution with a zero magnetic field to be stable to velocity perturbations. At the critical magnetic Reynolds number for the onset of instability of the trivial solution the dominant eigenvalue of the kinematic dynamo problem is real. In agreement with the bifurcation theory new steady states with non-vanishing magnetic field appear in this bifurcation. Subsequent bifurcations are investigated. A regime is detected, where chaotic variations of the magnetic field direction (analogous to magnetic field reversals) are observed in the temporal evolution of the system.

Podvigina, O M

2001-01-01

278

Development of periodic safety review plan for post-tensioning system in operating nuclear power plants  

International Nuclear Information System (INIS)

According to the Korean nuclear code, the safety review should be performed for operating nuclear power plants every 10 years. Although there have been studies and efforts of many scientists and engineers for integrity evaluation in NPPs, they were limited to most specific structures, systems, components and phenomena. Therefore they were insufficient for integrated evaluation in NPPs. By reason that the need of making confidence for the integrated safety in operating NPPs was raised, the overall integration and safety evaluation in NPPs have been performed through the periodic safety review (PSR). In this paper, plan and procedure of PSR will contribute to the enhanced safety of structures for post-tensioning system in containment building of operating NPPs

279

Dynamical tunneling of a Bose-Einstein condensate in periodically driven systems.  

Science.gov (United States)

We report measurements of dynamical tunneling rates of a Bose-Einstein condensate across a barrier in classical phase space. The atoms are initially prepared in quantum states that extend over a classically regular island region. We focus on the specific system of quantum accelerator modes of the kicked rotor in the presence of gravity. Our experimental data is supported by numerical simulations taking into account imperfections mainly from spontaneous emission. Furthermore, we predict experimentally accessible parameter ranges over which direct tunneling could be readily observed if spontaneous emission was further suppressed. Altogether, we provide a proof-of-principle for the experimental accessibility of dynamical tunneling rates in periodically driven systems. PMID:24125389

Shrestha, R K; Ni, J; Lam, W K; Summy, G S; Wimberger, S

2013-09-01

280

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. PMID:24125348

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

2013-09-01

 
 
 
 
281

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

282

Energy pay-back period analysis of stand-alone photovoltaic systems  

Energy Technology Data Exchange (ETDEWEB)

The exploitation of solar energy by autonomous, photovoltaic (PV) based systems offers the opportunity for satisfying the electrification needs of numerous remote consumers worldwide in an environmentally friendly way. On the other hand, the sustainable character of these systems is strongly questioned by the energy intensity of processes involved in the various life cycle (LC) stages of the system components. Although there are several studies concerned with the estimation of the energy pay-back period (EPBP) for grid-connected systems, the same is not valid for stand-alone configurations. In this context, an integrated methodology is currently developed in order to estimate the EPBP of PV-battery (PV-Bat) configurations ensuring 100% energy autonomy. The main scope of the proposed analysis is to determine the optimum size of a corresponding system, comprised of multi-crystalline (mc-Si) PV modules and lead-acid (PbA) batteries, based on the criterion of minimum embodied energy, i.e. minimum EPBP. For this purpose, a representative case study examined considers the electrification needs of a typical remote consumer on the Island of Rhodes, Greece. According to the results obtained, the autonomous energy character of the system is reflected by the comparatively higher EPBP in comparison with the corresponding grid-connected option, nevertheless the PV-Bat configurations analyzed clearly constitute sustainable energy solutions. Finally, in order to increase the reliability of the calculation results, a sensitivity analysis is carried out, based on the variation of the input energy content data. (author)

Kaldellis, J.K.; Zafirakis, D. [Lab of Soft Energy Applications and Environmental Protection, TEI Piraeus, P.O. Box 41046, Athens 12201 (Greece); Kondili, E. [Optimisation of Production Systems Lab, Mechanical Eng. Dept., TEI of Piraeus, P.O. Box 41046, Athens 12201 (Greece)

2010-07-15

283

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

International Nuclear Information System (INIS)

The chemical consequences of (n,2n) reactions on cristalline sodium iodate and periodates were investigated measuring the initial yield and the post irradiation thermal annealing yields (900C) of the separated fractions I-, IO3- and IO4-. NaIO3, NaIO3.H2O and NaIO4, Na4H2IO6, Na4I2O9.3H2O containing 127I and 129I, or both, were irradiated with 14 MeV neutrons. Results obtained show different effects for each system and that 126I and 128I isotopes keep the same behaviour in the irradiated compounds containing only ?127I or 129I and in compounds having both 127I and 129I. Neither isotope effect nor qualitative differences on thermal annealing at 900C were observed. The annealed fractions in the three studied periodates were IO-3 and IO-4. These results differ from the ones reported previously for (n,?) reactions on the same compounds

284

Photometric Study of the near-contact short period Algol system, AK Canis Minoris  

Science.gov (United States)

As a part of our departments new undergraduate research program, we are surveying the eccentric eclipsing binary (EEB) candidates of Hegedus (1988). AK CMi is listed as a system with a displaced secondary. The observations were taken 10 to 15 February 1994, inclusive, at Lowell Obsevatory, Flagstaff, Arizona. A thermoelectrically cooled EMI 6256S ( S-13 cathode) PMT was used in conjunction with the 0.78 m National Undergraduate Research Observatory reflector. Two precision epochs of minimicrons light were determined from the observations made during primary and secondary eclipses. They are: Min I = 2449396.7032(5) and Min II = 2449395.8546(3). Targeting the last twenty-three years of data, we calculated improved linear and quadratic ephemerides. The quadratic term, -1.0(2)E-10, suggests that AK CMi is undergoing a continuous period decrease. This may be due to magnetic braking arising from the fast rotating solar-type secondary component. There is little evidence from the present light curves that AK CMi has a eccentric orbit. Assymetries near secondary minima possibly induced by an intermittent gas stream may be responsible for the classification of AK CMi as an EEB. The light curve solution reveals that AK CMi is a short period Algol with an A spectral-type primary component and an early K-type secondary. We calculated mass ratio of 0.5 and a secondary component fillout of 90% showing that AK CMi is a near contact binary.

Samec, Ronald G.; McDermith, Richard J.; Gray, Jamison D.; Carrigan, Brian

1995-05-01

285

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

286

Load Balancing Using Time Series Analysis for Soft Real Time Systems with Statistically Periodic Loads  

Science.gov (United States)

This thesis provides design and analysis of techniques for global load balancing on ensemble architectures running soft-real-time object-oriented applications with statistically periodic loads. It focuses on estimating the instantaneous average load over all the processing elements. The major contribution is the use of explicit stochastic process models for both the loading and the averaging itself. These models are exploited via statistical time-series analysis and Bayesian inference to provide improved average load estimates, and thus to facilitate global load balancing. This thesis explains the distributed algorithms used and provides some optimality results. It also describes the algorithms' implementation and gives performance results from simulation. These results show that our techniques allow more accurate estimation of the global system load ing, resulting in fewer object migration than local methods. Our method is shown to provide superior performance, relative not only to static load-balancing schemes but also to many adaptive methods.

Hailperin, Max

1993-01-01

287

Stochastic Resonance of a Periodically Driven Bistable System with Two Different Kinds of Time Delays  

International Nuclear Information System (INIS)

In this paper, we study the phenomenon of stochastic resonance (SR) in a periodically driven bistable system with correlations between multiplicative and additive white noise terms when there are two different kinds of time delays existed in the deterministic and fluctuating forces, respectively. Using the small time delay approximation and the theory of signal-to-noise ratio (SNR) in the adiabatic limit, the expression of SNR is obtained. The effects of the delay time ? in the deterministic force, and the delay time ? in the fluctuating force on SNR are discussed. Based on the numerical computation, it is found that: (i) There appears a reentrant transition between one peak and two peaks and then to one peak again in the curve of SNR when the value of the time delay ? is increased. (ii) SR can be realized by tuning the time delay ? or ? with fixed noise, i.e., delay-induced stochastic resonance (DSR) exists. (general)

288

Discharge formation systems for generating atomic iodine in a pulse-periodic oxygen-iodine laser  

Science.gov (United States)

Generation characteristics of a pulse-periodic oxygen-iodine laser with the electro-discharge production of atomic iodine were compared with inductively stabilised edged or anisotropic- resistive cathodes used for ignition of the volume discharge. The discharge was initiated by the radiation of a barrier discharge from the side of a grid anode. It was found that at equal specific electrical energy depositions to the gas-discharge plasma, the system with the anisotropic-resistive cathode provides a more stable and uniform volume discharge with the possibility of varying the composition and pressure of working mixtures over a wide range and a greater specific extraction of laser energy is observed (up to 2.4 J L-1). At a high pulse repetition rate of laser pulses (50 - 100 Hz) and long duration of the pulse trains (longer than a minute) the surface of anisotropic-resistive cathode became eroded.

Aksinin, V. I.; Antsiferov, S. A.; Velikanov, S. D.; Gerasimov, A. Yu; Gostev, I. V.; Kazantsev, S. Yu; Kalinovskii, V. V.; Konovalov, V. V.; Kononov, I. G.; Mikhalkin, V. N.; Podlesnykh, S. V.; Sevryugin, I. V.; Firsov, K. N.

2014-01-01

289

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

International Nuclear Information System (INIS)

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

290

Stochastic resonance in a time-delayed asymmetric bistable system with mixed periodic signal  

International Nuclear Information System (INIS)

This paper studies the phenomenon of stochastic resonance in an asymmetric bistable system with time-delayed feedback and mixed periodic signal by using the theory of signal-to-noise ratio in the adiabatic limit. A general approximate Fokker–Planck equation and the expression of the signal-to-noise ratio are derived through the small time delay approximation at both fundamental harmonics and mixed harmonics. The effects of the additive noise intensity Q, multiplicative noise intensity D, static asymmetry r and delay time ? on the signal-to-noise ratio are discussed. It is found that the higher mixed harmonics and the static asymmetry r can restrain stochastic resonance, and the delay time ? can enhance stochastic resonance. Moreover, the longer the delay time ? is, the larger the additive noise intensity Q and the multiplicative noise intensity D are, when the stochastic resonance appears. (general)

291

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. PMID:24985415

Bi, Ping; Ruan, Shigui; Zhang, Xinan

2014-06-01

292

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

Directory of Open Access Journals (Sweden)

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

Cunhua Qian

2010-04-01

293

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

294

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

295

Light-harvesting three-chromophore systems based on biphenyl-bridged periodic mesoporous organosilica.  

Science.gov (United States)

Three-chromophore systems with light-harvesting behavior were prepared, which are based on periodic mesoporous organosilica (PMO) with crystal-like ordered structure. The organic bridges of biphenyl-PMO in the pore walls act as donors and two types of dye are incorporated in the one-dimensional channels. Consecutive two-step-Förster resonance energy transfer is observed from the biphenyl moieties to mediators (diethyl-aminocoumarin or aminoacridone), followed by energy transfer from mediators to acceptors (dibenzothiacarbocyanine, indodicarbocyanine, sulforhodamine?G). High energy-transfer efficiencies ranging from 70 to 80?% are obtained for two-step-FRET, indicating that the mesochannel structure with one-dimensional ordering provides spatial arrangement of chromophore pairs for an efficient direct energy transfer. The emission wavelength can be tuned by a choice of acceptor dye: 477?nm (diethylaminocoumarin), 519?nm (aminoacridone), 567?nm (sulforhodamine?G), 630?nm (dibenzothiacarbocyanine), and 692?nm (indodicarbocyanine). PMID:25352478

Grösch, Lyubov; Lee, Young Joo; Hoffmann, Frank; Fröba, Michael

2015-01-01

296

Assessment of the expected number and frequency of failures of periodically tested systems  

International Nuclear Information System (INIS)

The safety and reliability analysis of any system necessarily requires first to model its behavior or its failure logic, and second to assess its performance by using the previously chosen model. Among these performance indicators there is the failure frequency. In spite of its interest, it is not very often used, except in the standards devoted to the so-called functional safety, in which its genuine nature is not always made explicit. A sound method dedicated to the modeling and computing of the failure frequency of periodically tested systems is proposed in this paper. This type of systems comprises components with an availability curve which is discontinuous at deterministic instants. These discontinuities induce, in turn and at the same instants, frequency discontinuities. The impact of the latter on the overall value of the failure frequency is important, but largely unknown and therefore not taken into account in the safety and reliability area, in spite of the fact that it generally induces optimistic estimation, if no compensatory action is planned. The presented method is based on the notion of “critical state” and the use of advanced fault tree models (FT). The results obtained from these models are checked by using Monte Carlo simulation technique supported by equivalent Petri nets models (PN)

297

Connection between the periodic solutions of the Hamilton-Jacobi equation and the wave properties of the conservative bound systems  

International Nuclear Information System (INIS)

It is well known that the Schroedinger equation is equivalent to the wave equation for conservative bound quantum systems. Consequently, the motion of such a system is represented - from a mathematical point of view - by the motion of the characteristic surface of the wave equation. In this paper we present a demonstration of the periodic motion of the characteristic surface. It results that the normal curves of the characteristic surface are periodic solutions of the Hamilton-Jacobi equation written for the same system. This leads to a direct connection between the periodic solutions of the Hamilton-Jacobi equation and the wave properties of the system. The constants of motion corresponding to the above periodic solutions of the Hamilton-Jacobi equation are identical to the eigenvalues of the Schroedinger equation. These properties are proved without any approximation and they are valid for all the values of the principal quantum number

298

On the periodic dependence of baric coefficient of melting-point curves of simple substances  

International Nuclear Information System (INIS)

The values of the baric coefficient for simple substances have been refined on the basis of the Mendeleev's Periodic Law by two methods: plotting the correlative dependences of dT/dP on the conditional atomic volume; plotting the rigid schemes of relationships between dT/dP and atomic volume and by characteristics of the strength of an interatomic bond. The baric coefficient of the melting curves of simple bodies reflects a change in the character and strength of interatomic bonds upon transition from a solid state into liquid. This underlines the meaning of the baric coefficient as not only the characteristics of the phase transition nature but as an important property reflecting the character of electron melts

299

Wave-breaking phenomena and global solutions for periodic two-component Dullin-Gottwald-Holm systems  

Directory of Open Access Journals (Sweden)

Full Text Available In this article we study the initial-value problem for the periodic two-component b-family system, including a special case, when b = 2, which is referred to as the two-component Dullin-Gottwald-Holm (DGH system. We first show that the two-component b-family system can be derived from the theory of shallow-water waves moving over a linear shear flow. Then we establish several results of blow-up solutions corresponding to only wave breaking with certain initial profiles for the periodic two-component DGH system. Moreover, we determine the exact blow-up rate and lower bound of the lifespan for the system. Finally, we give a sufficient condition for the existence of the strong global solution to the periodic two-component DGH system.

Min Zhu

2013-02-01

300

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

Science.gov (United States)

...the comment period. The FAA believes...the NPRM and Initial Regulatory...of the pilot study. To address...the NPRM or Initial Regulatory...a 30-day period for the public...the NPRM and Initial Regulatory...third pilot study or AC would...the comment period open...

2011-03-07

 
 
 
 
301

Persistence and Existence of Periodic Solution for Predator-Prey System with Holling-N Type Functional Response  

Directory of Open Access Journals (Sweden)

Full Text Available Based on the previous studies of functional reaction Holling limited predator-prey system, this paper expands Limited class to N and discusses the permanence and existence of periodic solution for predator-prey system with Holling-N type functional response. Firstly, a discrete model of the systemis formulated.Then ,by the skills of inequalities,we obtain a sufficient condition ensuring the permanence for predator-prey system.*, where *. Under the assumption of *, based on the results ,the existence of periodic solution of system is derived by using Brouwer fixed point theory.(* Indicates a formula, please see the full text

YANG Zhi-chun

2010-09-01

302

Frictional systems under periodic loads — History-dependence, non-uniqueness and energy dissipation  

International Nuclear Information System (INIS)

Nominally static contacts such as bolted or shrink-fit joints typically experience regions of microslip when subjected to oscillatory loading. This results in energy dissipation, reflected as apparent hysteretic damping of the system, and also may cause the initiation of fretting fatigue cracks. Early theoretical studies of the Hertzian contact problem by Cattaneo and Mindlin were confirmed experimentally by Johnson, who identified signs of fretting damage in the slip annulus predicted by the theory. For many years, tribologists assumed that Melan's theorem in plasticity could be extended to frictional systems — i.e. that if there exists a state of residual stress associated with frictional slip that is sufficient to prevent periodic slip in the steady state, then the system will shake down, regardless of the initial condition. However, we now know that this is true only if there is no coupling between the normal and tangential loading problems, as will be the case notably when contact occurs on a symmetry plane. For all other cases, periodic loading scenarios can be devised such that shakedown occurs for some initial conditions and not for others. The initial condition here might be determined by the assembly protocol — e.g. the order in which a set of bolts is tightened — or by the exact loading path before the steady cycle is attained. This non-uniqueness of the steady state persists at load amplitudes above the shakedown limit, in which case there is always imit, in which case there is always some dissipation, but the dissipation per cycle (and hence both the effective damping and the susceptibility to fretting damage) depends on the initial conditions. This implies that fretting fatigue experiments need to follow a well-defined assembly protocol if reproducible results are to be obtained. We shall also present results showing that when both normal and tangential forces vary in time, the energy dissipation is very sensitive to the relative phase of the oscillatory components, being greatest when they are out of phase. With sufficient clamping force, 'complete' contacts (i.e. those in which the contact area is independent of the normal load) can theoretically be prevented from slipping, but on the microscale, all contacts are incomplete because of surface roughness and some microslip is inevitable. In this case, the local energy dissipation density can be estimated from relatively coarse-scale roughness models, based on a solution of the corresponding 'full stick' problem.

303

Frictional systems under periodic loads — History-dependence, non-uniqueness and energy dissipation  

Science.gov (United States)

Nominally static contacts such as bolted or shrink-fit joints typically experience regions of microslip when subjected to oscillatory loading. This results in energy dissipation, reflected as apparent hysteretic damping of the system, and also may cause the initiation of fretting fatigue cracks. Early theoretical studies of the Hertzian contact problem by Cattaneo and Mindlin were confirmed experimentally by Johnson, who identified signs of fretting damage in the slip annulus predicted by the theory. For many years, tribologists assumed that Melan's theorem in plasticity could be extended to frictional systems — i.e. that if there exists a state of residual stress associated with frictional slip that is sufficient to prevent periodic slip in the steady state, then the system will shake down, regardless of the initial condition. However, we now know that this is true only if there is no coupling between the normal and tangential loading problems, as will be the case notably when contact occurs on a symmetry plane. For all other cases, periodic loading scenarios can be devised such that shakedown occurs for some initial conditions and not for others. The initial condition here might be determined by the assembly protocol — e.g. the order in which a set of bolts is tightened — or by the exact loading path before the steady cycle is attained. This non-uniqueness of the steady state persists at load amplitudes above the shakedown limit, in which case there is always some dissipation, but the dissipation per cycle (and hence both the effective damping and the susceptibility to fretting damage) depends on the initial conditions. This implies that fretting fatigue experiments need to follow a well-defined assembly protocol if reproducible results are to be obtained. We shall also present results showing that when both normal and tangential forces vary in time, the energy dissipation is very sensitive to the relative phase of the oscillatory components, being greatest when they are out of phase. With sufficient clamping force, 'complete' contacts (i.e. those in which the contact area is independent of the normal load) can theoretically be prevented from slipping, but on the microscale, all contacts are incomplete because of surface roughness and some microslip is inevitable. In this case, the local energy dissipation density can be estimated from relatively coarse-scale roughness models, based on a solution of the corresponding 'full stick' problem.

Barber, J. R.

2012-08-01

304

The Endocannabinoid System in the Postimplantation Period: A Role during Decidualization and Placentation  

Science.gov (United States)

Although the detrimental effects of cannabis consumption during gestation are known for years, the vast majority of studies established a link between cannabis consumption and foetal development. The complex maternal-foetal interrelationships within the placental bed are essential for normal pregnancy, and decidua definitively contributes to the success of this process. Nevertheless, the molecular signalling network that coordinates strategies for successful decidualization and placentation are not well understood. The discovery of the endocannabinoid system highlighted new signalling mediators in various physiological processes, including reproduction. It is known that endocannabinoids present regulatory functions during blastocyst development, oviductal transport, and implantation. In addition, all the endocannabinoid machinery was found to be expressed in decidual and placental tissues. Additionally, endocannabinoid's plasmatic levels were found to fluctuate during normal gestation and to induce decidual cell death and disturb normal placental development. Moreover, aberrant endocannabinoid signalling during the period of placental development has been associated with pregnancy disorders. It indicates the existence of a possible regulatory role for these molecules during decidualization and placentation processes, which are known to be particularly vulnerable. In this review, the influence of the endocannabinoid system in these critical processes is explored and discussed. PMID:24228028

Fonseca, B. M.; Correia-da-Silva, G.; Almada, M.; Costa, M. A.; Teixeira, N. A.

2013-01-01

305

Short-period low-mass binary system CC Com revisited  

CERN Document Server

In this study we determined precise orbital and physical parameters of the very short period low-mass contact binary system CC Com. The parameters are obtained by analysis of the new CCD data with the archival spectroscopic data. The physical parameters of the components derived as $M_\\textrm{c}$ = 0.717(14) $M_{\\odot}$, $M_\\textrm{h}$ = 0.378(8) $M_{\\odot}$, $R_\\textrm{c}$ = 0.708(12) $R_{\\odot}$, $R_\\textrm{h}$ = 0.530(10) $R_{\\odot}$, $L_\\textrm{c}$ = 0.138(12) $L_{\\odot}$, $L_\\textrm{h}$ = 0.085(7) $L_{\\odot}$, and the distance of the system is estimated as 64(4) pc. The times of minima obtained in this study and with those published before enable us to calculate the mass transfer rate between the components which is $1.6\\times10^{-8}$ M$_{\\odot}$yr$^{-1}$. Finally, we discuss the possible evolutionary scenario of CC Com.

Kose, O; Keskin, V; Ulas, B; Yakut, K

2011-01-01

306

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

CERN Document Server

We present high-precision photometry of five consecutive transits of WASP-18, an extrasolar planetary system with one of the shortest orbital periods known. Through the use of telescope defocussing we achieve a photometric precision of 0.47 to 0.83 mmag per observation over complete transit events. The data are analysed using the JKTEBOP code and three different sets of stellar evolutionary models. We find the mass and radius of the planet to be M_b = 10.43 +/- 0.30 +/- 0.24 Mjup R_b = 1.165 +/- 0.055 +/- 0.014 Rjup (statistical and systematic errors) respectively. The systematic errors in the orbital separation and the stellar and planetary masses, arising from the use of theoretical predictions, are of a similar size to the statistical errors and set a limit on our understanding of the WASP-18 system. We point out that seven of the nine known massive transiting planets (M_b > 3 Mjup) have eccentric orbits, whereas significant orbital eccentricity has been detected for only four of the 46 less massive planet...

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

2009-01-01

307

Verification of precipitation from the NWP nowcasting system at the DMI for a wet summer period  

Science.gov (United States)

At the Danish Meteorological Institute the operational nowcasting modeling system utilizes a newly introduced nudging-based radar-assimilation technique (Korsholm et al., 2014) in the NWP model. In this method radar-derived rain-rates are used to estimate a vertical profile of horizontal divergence that the horizontal divergence in the model is nudged towards. Verification of precipitation forecasts by the nowcasting system using this technique is presented for 17 days of august 2010 and compared to a reference where the radar nudging is excluded. In Denmark this period in 2010 was particularly wet with several heavy precipitation events with observed precipitation above 36 mm of rain during one hour. Three of these events are studied in some detail. The verification is based on fractional skill scores which give scale-selective scores of the spatial skill of the forecasts based on radar-derived precipitation fields. The study shows that for precipitation values above the 95th percentile the nudging technique have a strong impact on the spatial skill of the forecast in the first 1-2 hours, and a smaller but still clear impact on the 3-4 hour forecast length where skill percists in the forecast on scales down to tens of kilometers. It is clear that the spatial smoothing of the model reduce the forecast quality, and some indications of positive bias in precipitation intensities are observed.

Olsen, Bjarke Tobias; Smith Korsholm, Ulrik; Petersen, Claus; Woetmann Nielsen, Niels; Vedel, Henrik; Hansen Sass, Bent

2014-05-01

308

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

Science.gov (United States)

The Lop Nur region is located in the east of the Tarim Basin. It has served as the strategic passage and communication hub of the Silk Road since Han Dynasty. During Wei-Jin period, the river system there was well developed and the ancient city of Loulan was bred there. In this study, GIS is used to accomplish automatic extraction of the river course in the Lop Nur region at first using ArcGIS. Then the RCI index is constituted to extract ancient river course from Landsat ETM image with band 3 and band 4. It is concluded that the north river course of Peacock River conformed before the end of the 4th century AD according to the distribution of the entire river course of the Lop Nur region. Later, the Peacock River changed its way to south to Tarim River, and flowed into Lop Nur along the direction paralleling Altun Mountain from west to east. It was the change of the river system that mainly caused the decrease in water supply around ancient city of Loulan before the end of 4th century. The ancient city of Loulan has been gradually ruined in the sand because of the absence of water supply since then.

Zhu, Jianfeng; Jia, Peng; Nie, Yueping

2010-09-01

309

Interuser Interference Analysis for Direct-Sequence Spread-Spectrum Systems Part I: Partial-Period Cross-Correlation  

Science.gov (United States)

This presentation discusses an analysis approach to evaluate the interuser interference for Direct-Sequence Spread-Spectrum (DSSS) Systems for Space Network (SN) Users. Part I of this analysis shows that the correlation property of pseudo noise (PN) sequences is the critical factor which determines the interuser interference performance of the DSSS system. For non-standard DSSS systems in which PN sequence s period is much larger than one data symbol duration, it is the partial-period cross-correlation that determines the system performance. This study reveals through an example that a well-designed PN sequence set (e.g. Gold Sequence, in which the cross-correlation for a whole-period is well controlled) may have non-controlled partial-period cross-correlation which could cause severe interuser interference for a DSSS system. Since the analytical derivation of performance metric (bit error rate or signal-to-noise ratio) based on partial-period cross-correlation is prohibitive, the performance degradation due to partial-period cross-correlation will be evaluated using simulation in Part II of this analysis in the future.

Ni, Jianjun (David)

2012-01-01

310

Orbital periods of cataclysmic variables identified by the SDSS. IX. NTT photometry of eight eclipsing and three magnetic systems  

CERN Document Server

We report the discovery of eclipses and the first orbital period measurements for four cataclysmic variables, plus the first orbital period measurements for one known eclipsing and two magnetic systems. SDSS J093537.46+161950.8 exhibits 1-mag deep eclipses with a period of 92.245 min. SDSS J105754.25+275947.5 has short and deep eclipses and an orbital period of 90.44 min. Its light curve has no trace of a bright spot and its spectrum is dominated by the white dwarf component, suggesting a low mass accretion rate and a very low-mass and cool secondary star. CSS J132536+210037 shows 1-mag deep eclipses each separated by 89.821 min. SDSS J075653.11+085831.8 shows 2-mag deep eclipses on a period of 197.154 min. CSS J112634-100210 is an eclipsing dwarf nova identified in the Catalina Real Time Transit Survey, for which we measure a period of 111.523 min. SDSS J092122.84+203857.1 is a magnetic system with an orbital period of 84.240 min; its light curve is a textbook example of cyclotron beaming. A period of 158.72...

Southworth, John; Gaensicke, B T; Copperwheat, C M

2014-01-01

311

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

312

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.)

313

Upper gastrointestinal system bleeding treated by somatostatin analogue (ocreotide in the neonatal period: a case report  

Directory of Open Access Journals (Sweden)

Full Text Available In the neonatal period, upper gastrointestinal system (GIS bleeding may be due to benign disorders which do not require any treatments or may be relevant to serious conditions requiring urgent intervention. There are two major causes of upper GIS bleeding developed in the newborns; vitamin K deficiency-induced hemorrhagic disease of the newborn and maternal blood swallowed during birth. Other causes of this type of bleeding include gastritis, esophagitis, peptic ulcus (PU, coagulopathy, sepsis, vascular malformations, trauma, and esofageal-gastric duplications. Rarely, gastric erosion or perforation due to oro/naso gastric tube might cause severe upper GIS bleeding. Hemodynamic resuscitation, bleeding control, and prevention of the recurrence form the basis of the management. However, a somatostatin analogue (ocreotide may be helpful by reducing the splanchnic blood if bleeding is caused by a known vascular lesion or arterial erosion. In this paper, a case of newborn with upper GIS bleeding developed within the first 24 hour life and probably caused by arterial erosion due to oro/gastric tube and treated by ocreotide was presented in the light of literature.

Afsin Kundak

2014-01-01

314

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

Directory of Open Access Journals (Sweden)

Full Text Available The objective of the present study is the design of log periodic ring printed antennas array witch generates circular polarization with wide band by single feed linearly polarized elements for GPS systems. The radiating elements have been fed by magnetic coupling through a slot. The circular polarization is achieved by having a basic 2×2 sub-arrays with unique element angular and phase arrangement, both the element angular orientation and feed phase are arranged in the 0°, 90°, 180 and 270° fashion. The purpose of different angular orientations of the patches is to generate two orthogonally polarized fields, while -3dB coupler is used to provide the required amplitude and phase delays for circular polarization generation. This uniquely formed array has the capability of generating excellent circular polarization. An association of the coupler with the antennas has been established.This work is completed using the moment’s method of Momentum software. Good performances of adaptation and polarization were obtained. The simulation results are then presented and discussed.

M. Abri

2012-06-01

315

Review of nuclear air treatment system related License Event Reports for the period 1985 - 1987  

International Nuclear Information System (INIS)

This paper will continue the review of HVAC/NATS related LERS presented at past Air Cleaning Conferences by Dr. D. W. Moeller and his associates. The general approach and format are similar. LER abstracts from mid 1985 through 1987 were reviewed and those related to HVAC/NATS classified and analyzed. The categories were jointly developed by Dr. Moeller, Dr. Casper Sun and myself. In appropriate cases both primary and secondary categories fora problem are given. A basic listing by category and brief statistical review are presented. Additionally a number of categories are discussed in some detail. The categories chosen for specific review are intended to highlight particular problem areas. NUREG/CR-2000 License Event Report (LER) Compilation is the basis for the initial review and coding. In essentially all cases where an LER is classified as of interest the complete LER was obtained and reviewed in full. The intent of this paper is to provide a basis for the industry to document and analyze problem areas that require additional attention. It appears that about 15% of all LERS in the subject period are HVAC/NATS related. This figure is generally consistent with those reported at the 17th DOE Nuclear Air Cleaning Conference. It is hoped that such attention will allow additional resources to be allocated to upgrade systems, procedures and training as well as in some cases government regulation

316

Unavailability, spurious operation and cost analysis of periodically tested and maintained standby k-out- of-n systems  

International Nuclear Information System (INIS)

Control systems in safety-critical applications often consist of two categories: on-line systems and standby systems. When the on-line systems fail to operate properly, the standby systems should automatically take actions to prevent any catastrophic consequences. However, the standby systems might fail as well. Therefore, regular test and maintenance need to be performed to reveal hidden failures. The objective of this paper is to investigate and compare there test and maintenance strategies for a standby k-out-of-n safety-critical system. The three strategies are periodic test, periodic preventive maintenance and periodic predictive maintenance and they are all performed on-line. Each channel of the k-out-of-n system adopts an age-dependent reliability model. Based on this model, the system unavailability, the probability of spurious operation and the overall cost are investigated, with consideration of the three test and maintenance strategies. One of the main standby safety systems in Canadian Deuterium-Uranium (CANDU) based Nuclear Power Plants (NPPs), the Shutdown System Number One (SDS1), is used as an example to illustrate the proposed analysis. (authors)

317

Orbital periods of cataclysmic variables identified by the SDSS. IX. NTT photometry of eight eclipsing and three magnetic systems  

Science.gov (United States)

We report the discovery of eclipses and the first orbital period measurements for four cataclysmic variables, plus the first orbital period measurements for one known eclipsing and two magnetic systems. SDSS J093537.46+161950.8 exhibits 1 mag deep eclipses with a period of 92.245 min. SDSS J105754.25+275947.5 has short and deep eclipses and an orbital period of 90.44 min. Its light curve has no trace of a bright spot and its spectrum is dominated by the white dwarf component, suggesting a low mass accretion rate and a very low-mass and cool secondary star. CSS J132536+210037 shows 1 mag deep eclipses each separated by 89.821 min. SDSS J075653.11+085831.8 shows 2 mag deep eclipses on a period of 197.154 min. CSS J112634-100210 is an eclipsing dwarf nova identified in the Catalina Real Time Transit Survey, for which we measure a period of 111.523 min. SDSS J092122.84+203857.1 is a magnetic system with an orbital period of 84.240 min; its light curve is a textbook example of cyclotron beaming. A period of 158.72 min is found for the faint magnetic system SDSS J132411.57+032050.4, whose orbital light variations are reminiscent of AM Her. Improved orbital period measurements are also given for three known SDSS cataclysmic variables. We investigate the orbital period distribution and fraction of eclipsing systems within the SDSS sample and for all cataclysmic variables with a known orbital period, with the finding that the fraction of known CVs which are eclipsing is not strongly dependent on the orbital period. The reduced observational data presented in this work are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/573/A61 and at http://www.astro.keele.ac.uk/~jkt/

Southworth, J.; Tappert, C.; Gänsicke, B. T.; Copperwheat, C. M.

2015-01-01

318

The rate of convergence of new Lax–Oleinik type operators for time-periodic positive definite Lagrangian systems  

International Nuclear Information System (INIS)

Assume that the Aubry set of the time-periodic positive definite Lagrangian L consists of one hyperbolic 1-periodic orbit. We provide an upper bound estimate of the rate of convergence of the family of new Lax–Oleinik type operators associated with L introduced by the authors in Wang and Yan (2012 Commun. Math. Phys. 309 663–91). In addition, we construct an example where the Aubry set of a time-independent positive definite Lagrangian system consists of one hyperbolic periodic orbit and the rate of convergence of the Lax–Oleinik semigroup cannot be better than O(1/t) as t ? +?

319

DISK-PLANETS INTERACTIONS AND THE DIVERSITY OF PERIOD RATIOS IN KEPLER'S MULTI-PLANETARY SYSTEMS  

Energy Technology Data Exchange (ETDEWEB)

The Kepler mission is dramatically increasing the number of planets known in multi-planetary systems. Many adjacent planets have orbital period ratios near resonant values, with a tendency to be larger than required for exact first-order mean-motion resonances. This feature has been shown to be a natural outcome of orbital circularization of resonant planetary pairs due to star-planet tidal interactions. However, this feature holds in multi-planetary systems with periods longer than 10 days, in which tidal circularization is unlikely to provide efficient divergent evolution of the planets' orbits to explain these orbital period ratios. Gravitational interactions between planets and their parent protoplanetary disk may instead provide efficient divergent evolution. For a planet pair embedded in a disk, we show that interactions between a planet and the wake of its companion can reverse convergent migration and significantly increase the period ratio from a near-resonant value. Divergent evolution due to wake-planet interactions is particularly efficient when at least one of the planets opens a partial gap around its orbit. This mechanism could help account for the diversity of period ratios in Kepler's multiple systems from super-Earth to sub-Jovian planets with periods greater than about 10 days. Diversity is also expected for pairs of planets massive enough to merge their gap. The efficiency of wake-planet interactions is then much reduced, but convergent migration may stall with a variety of period ratios depending on the density structure in the common gap. This is illustrated for the Kepler-46 system, for which we reproduce the period ratio of Kepler-46b and c.

Baruteau, Clement; Papaloizou, John C. B., E-mail: C.Baruteau@damtp.cam.ac.uk, E-mail: J.C.B.Papaloizou@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics (DAMTP), University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

2013-11-20

320

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

 
 
 
 
321

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 t...

Paulo Fortes Neto; Luis Carlos Laureano da Rosa; Mariko Ueno; Juliano Guimarães Assumpção

2011-01-01

322

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

323

An efficient tracer experimental design for measuring time-variable transit time distributions in periodic hydrodynamic systems  

Science.gov (United States)

The time-varying transport dynamics of complex hydrodynamic systems with long transit times are difficult to observe even in experimental systems due to the need for multiple tracer injections. Where only one or two distinct tracers are available, overprinting in the output concentrations limits the injection frequency. We will present an experimental method (the PERiodic Tracer Hierarchy - PERTH) that allows overprinted breakthrough curves to be decomposed into contributions from multiple injections of the same tracer, so long as the transporting flow is periodic. This method allows the time varying transit time distributions to be observed efficiently while making no a priori assumptions about the transport processes operating in the system. Simulations of transport through a soil column subject to a periodic sequence of irrigation events demonstrate that the distinct transit time distributions associated with each irrigation event can be retrieved almost exactly.

Harman, Ciaran; Kim, Minseok

2014-05-01

324

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

Energy Technology Data Exchange (ETDEWEB)

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.

Rothe, R.E.

1996-09-30

325

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

326

A dynamical systems analysis of the kinematics of time-periodic vortex shedding past a circular cylinder  

Science.gov (United States)

Computer flow simulation aided by dynamical systems analysis is used to investigate the kinematics of time-periodic vortex shedding past a two-dimensional circular cylinder in the context of the following general questions: (1) Is a dynamical systems viewpoint useful in the understanding of this and similar problems involving time-periodic shedding behind bluff bodies; and (2) Is it indeed possible, by adopting such a point of view, to complement previous analyses or to understand kinematical aspects of the vortex shedding process that somehow remained hidden in previous approaches. We argue that the answers to these questions are positive. Results are described.

Ottino, Julio M.

1991-01-01

327

Microwave photoconductivity of a periodically modulated two-dimensional electron system: Striped states and overlapping Landau levels  

CERN Document Server

We study the dc-response of the striped state under microwave irradiation. The striped state can be modeled by a two-dimensional electron system under the influence of a unidirectional periodic modulation potential, which was examined in [J. Dietel et al. Phys. Rev. B (71), 045329 (2005)]. We further extend our study of the periodically modulated system to the case of strongly overlapping Landau levels and calculate the dark and photoconductivities. The strength of the modulation potential serves as an additional parameter which allows to vary the overlap of the Landau levels independently of the filling fraction.

Dietel, J

2005-01-01

328

Photometric Investigation and Possible Light-Time Effect in the Orbital Period of a Marginal Contact System, CW Cassiopeiae  

Science.gov (United States)

The first complete charge-coupled device (CCD) light curves in B and V passbands of a neglected contact binary system, CW Cassiopeiae (CW Cas), are presented. They were analyzed simultaneously by using the Wilson and Devinney (WD) code (1971, ApJ, 166, 605). The photometric solution indicates that CW Cas is a W-type W UMa system with a mass ratio of m2/m1 2.234, and that it is in a marginal contact state with a contact degree of ˜6.5% and a relatively large temperature difference of ˜327K between its two components. Based on the minimum times collected from the literature, together with the new ones obtained in this study, the orbital period changes of CW Cas were investigated in detail. It was found that a periodical variation overlaps with a secular period decrease in its orbital period. The long-term period decrease with a rate of dP/dt = -3.44 × 10-8d yr-1 can be interpreted either by mass transfer from the more-massive component to the less-massive with a rate of dm2/dt = -3.6 × 10-8M? yr-1, or by mass and angular-momentum losses through magnetic braking due to a magnetic stellar wind. A low-amplitude cyclic variation with a period of T = 63.7 yr might be caused by the light-time effect due to the presence of a third body.

Jiang, Tian-Yu; Li, Li-Fang; Han, Zhan-Wen; Jiang, Deng-Kai

2010-04-01

329

75 FR 76928 - Safety Management System for Certificated Airports; Extension of Comment Period  

Science.gov (United States)

...OF TRANSPORTATION Federal Aviation Administration 14 CFR Part...Comment Period AGENCY: Federal Aviation Administration (FAA), DOT...for its entire airfield environment (including movement and non...representing airports and other aviation industry segments have...

2010-12-10

330

On the structure of the set of bifurcation points of periodic solutions for multiparameter Hamiltonian systems  

CERN Document Server

This paper deals with periodic solutions of the Hamilton equation with many parameters. Theorems on global bifurcation of solutions with periods $2\\pi/j,$ $j\\in\\mathbb{N},$ from a stationary point are proved. The Hessian matrix of the Hamiltonian at the stationary point can be singular. However, it is assumed that the local topological degree of the gradient of the Hamiltonian at the stationary point is nonzero. It is shown that (global) bifurcation points of solutions with given periods can be identified with zeros of appropriate continuous functions on the space of parameters. Explicit formulae for such functions are given in the case when the Hessian matrix of the Hamiltonian at the stationary point is block-diagonal. Symmetry breaking results concerning bifurcation of solutions with different minimal periods are obtained. A geometric description of the set of bifurcation points is given. Examples of constructive application of the theorems proved to analytical and numerical investigation and visualization...

Radzki, Wiktor

2008-01-01

331

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

332

Non-existence of periodic solutions in fractional-order dynamical systems and a remarkable difference between integer and fractional-order derivatives of periodic functions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Using the Mellin transform approach, it is shown that, in contrast with integer-order derivatives, the fractional-order derivative of a periodic function cannot be a function with the same period. The three most widely used definitions of fractional-order derivatives are taken into account, namely, the Caputo, Riemann-Liouville and Grunwald-Letnikov definitions. As a consequence, the non-existence of exact periodic solutions in a wide class of fractional-order dynamical syst...

Kaslik, Eva; Sivasundaram, Seenith

2011-01-01

333

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)

334

Assessment of Tension of the Students’ Organism Regulatory Systems during the Initial Period of Study at the University  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The article presents research results of the current functional state of students by recording the heart rate variability during the study period. Imbalance of parts of the autonomic nervous system and reactivity reduction of parasympathetic and sympathetic divisions at large number of examinees were detected.

Konkabaeva, Aiman E.; Kozhuhova, Sabina S.; Bodeeva, Rakhat T.

2012-01-01

335

Assessment of Tension of the Students’ Organism Regulatory Systems during the Initial Period of Study at the University  

Directory of Open Access Journals (Sweden)

Full Text Available The article presents research results of the current functional state of students by recording the heart rate variability during the study period. Imbalance of parts of the autonomic nervous system and reactivity reduction of parasympathetic and sympathetic divisions at large number of examinees were detected.

Aiman E. Konkabaeva

2012-08-01

336

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

337

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

338

Modeling, analysis, and robust controls for electrophotographic imaging systems subject to spatially periodic disturbances and measurable nonlinearities  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis is devoted to modeling, identification, control, and performance improvement for a class of electrophotography (EP)-based imaging systems, which are commercially known as laser printers. For this type of systems, halftone banding is a well-known artifact that causes periodic density variation perpendicular to the print direction on printed images. It is known that gear eccentricity and tooth profile error are main contributors to scanline spacing variation, which introduces densit...

Chen, Cheng-lun

2003-01-01

339

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

340

A New Framework For Helicopter Vibration Suppression; Time-Periodic System Identification and Controller Design  

Science.gov (United States)

In forward flight, helicopter rotor blades function within a highly complex aerodynamic environment that includes both near-blade and far-blade aerodynamic phenomena. These aerodynamic phenomena cause fluctuating aerodynamic loads on the rotor blades. These loads when coupled with the dynamic characteristics and elastic motion of the blade create excessive amount of vibration. These vibrations degrade helicopter performance, passenger comfort and contributes to high cost maintenance problems. In an effort to suppress helicopter vibration, recent studies have developed active control strategies using active pitch links, flaps, twist actuation and higher harmonic control of the swash plate. In active helicopter vibration control, designing a controller in a computationally efficient way requires accurate reduced-order models of complex helicopter aeroelasticity. In previous studies, controllers were designed using aeroelastic models that were obtained by coupling independently reduced aerodynamic and structural dynamic models. Unfortunately, these controllers could not satisfy stability and performance criteria when implemented in high-fidelity computer simulations or real-time experiments. In this thesis, we present a novel approach that provides accurate time-periodic reduced-order models and time-periodic H2 and H infinity controllers that satisfy the stability and performance criteria. Computational efficiency and the necessity of using the approach were validated by implementing an actively controlled flap strategy. In this proposed approach, the reduced-order models were directly identified from high-fidelity coupled aeroelastic analysis by using the time-periodic subspace identification method. Time-periodic H2 and Hinfinity controllers that update the control actuation at every time step were designed. The control synthesis problem was solved using Linear Matrix Inequality and periodic Riccati Equation based formulations, for which an in-house periodic Riccati solver was developed. The results show that first, important helicopter aeroelastic features can only be captured using high-fidelity coupled aeroelastic analysis; ignoring these features through uncoupled analysis leads to closed-loop performance degradation and instabilities. Second, time-periodic models are necessary to obtain an accurate map between control actuation and helicopter aeroelastic response; time-invariant models fail to provide accurate prediction. Third, time-Periodic H2 and H infinity controllers satisfy the stability and design performance criteria when implemented in high-fidelity aeroelastic analysis. Finally, we propose robust H2 and Hinfinity controller design strategies that are capable of modeling variable advance ratios.

Ulker, Fatma Demet

 
 
 
 
341

The first photometric analysis and period investigation of the W UMa type binary system V1139 Cas  

Science.gov (United States)

V1139 Cas, which is a very short period W UMa type binary star, was a neglected object since its discovery. BVRI light curves of this system observed using the 1 m telescope at Weihai Observatory of Shandong University are presented and are analyzed using the Wilson-Devinney code. It is discovered that V1139 Cas is a shallow contact binary system (f=3.6%) with a mass ratio of q=1.583. By using all available times of minimum light, the orbital period variation is studied for the first time. We found that the orbital period has varied by a combination of an downward parabola and a sinusoid. The downward parabola means continuous period decrease at a rate of dP/dt=3.66×10-7 d yr-1 and may be caused by angular momentum loss via stellar wind. The sinusoidal variation with a period of 12.8 yr and a semi-amplitude of 0.0064 days can most likely be interpreted as the light travel time effect due to the existence of an unseen tertiary companion.

Li, K.; Hu, S.-M.; Guo, D.-F.; Jiang, Y.-G.; Gao, D.-Y.; Chen, X.

2015-01-01

342

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

CERN Document Server

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

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

2007-01-01

343

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

344

18 CFR 301.4 - Exchange Period Average System Cost determination.  

Science.gov (United States)

...the ASC forecast model to calculate the...Bonneville's most current forecast of natural...the same rate of growth as total Contract...However, load growth will be assumed...Load, as well as a current distribution...Period. (e) Load growth not met by...

2010-04-01

345

Diffusion in a quasi-one-dimensional system on a periodic substrate.  

Science.gov (United States)

The diffusion of charged particles interacting through a repulsive Yukawa potential, exp(-r/?)/r, confined by a parabolic potential in the y direction and subjected to a periodic substrate potential in the x direction is investigated. Langevin dynamic simulations are used to investigate the effect of the particle density, the amplitude of the periodic substrate, and the range of the interparticle interaction potential on the diffusive behavior of the particles. We found that in general the diffusion is suppressed with increasing the amplitude of the periodic potential, but for specific values of the strength of the substrate potential a remarkable increase of the diffusion is found with increasing the periodic potential amplitude. In addition, we found a strong dependence of the diffusion on the specific arrangement of the particles, e.g., single-chain versus multichain configuration. For certain particle configurations, a reentrant behavior of the diffusion is found as a function of the substrate strength due to structural transitions in the ordering of the particles. PMID:22463181

Carvalho, J C N; Nelissen, K; Ferreira, W P; Farias, G A; Peeters, F M

2012-02-01

346

[Pharmacists (Yakuzaikan) in the Japanese Military System during the Meiji period].  

Science.gov (United States)

The medical organization in the Japanese Army and the activity of army pharmacists during the Meiji period (1868-1912) are described. The army pharmacists worked to not only prepare medicines in the pharmacies of military hospitals, but also were in charge of supplying and maintaining medical machinery, equipment and other materials including bandages, gauzes, etc. used by the army troops. Basically, the responsibilities for these tasks have been passed on to the present self Defense Force pharmacists. Some army pharmacists went to Germany with the aide of governmental scholarships or at their own expense to study advanced pharmacy during Meiji period. The first army clinic was founded in Meiji 1 (1868), and the number of army hospitals increased to a total of 87 in all Japanese territories including Korea, Manchuria, Taiwan and South Sakhalin in Meiji 43 (1910). The number of Japanese army doctors and pharmacists working in the Meiji period, as well as their titles, are also reported. The activities of army pharmacists during the Meiji period are more specifically clarified as well. PMID:19227659

Horiguchi, Norihiro

2008-01-01

347

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

CERN Document Server

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

348

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.

2472-24-01

349

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

350

[Effect of alimentary protein deficiency in the early postnatal period on the function of the immunocompetent system in rats].  

Science.gov (United States)

The influence of protein deficiency in the early postnatal period on the functional and morphological characteristics of the immunocompetent system was studied in 76 test and 60 control rats, 4 and 12 months after the experiment commencement. It was shown that protein deficiency in the early postnatal period induced shifts in the cellular parameters of the immunologic responsiveness, mainly, producing no significant changes in the nonspecific factors of body defence. The impairing effect of protein deficiency was more manifest at the early steps of the body development. PMID:3765538

Volgarev, M N; Sergeeva, K V; Trushina, E N; Tokareva, T V; Leshcheva, O A

1986-01-01

351

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

352

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 sys, 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

353

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

354

Determination of induction period and crystal growth mechanism of dexamethasone sodium phosphate in methanol-acetone system  

Science.gov (United States)

The induction period of dexamethasone sodium phosphate at different supersaturation was experimentally determined in a methanol-acetone system. The laser monitoring observation technique was used to determine the appearance of the first nucleus in solution. The effect of solution composition on induction period was discussed. Based on classical homogeneous nucleation theory, the solid-liquid interfacial tension and surface entropy factor were calculated from the induction period data. The experimentally determined values of interfacial tension are in agreement with the theoretical values predicted by the Mersmann equation. It was found that the nucleus of dexamethasone sodium phosphate grows continuously in pure methanol and turns from continuous growth to birth and spread growth with increasing acetone content in a methanol-acetone mixture.

Hao, Hongxun; Wang, Jingkang; Wang, Yongli

2005-02-01

355

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

CERN Document Server

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

Makarenkov, Oleg

2007-01-01

356

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)

357

Operator support systems in NPPs. Summary of the activities in the period 1993-1995  

International Nuclear Information System (INIS)

The report presents an overview of major activities performed in ENEA and ANPA in the period 1993-1995 related to CRP subject. Being in Italy the Nuclear Power Plant not in operation since 1987, studied and research under development related to the CRP subject make reference to technological themes such as the methods to improve the software quality in critical application and the methods to improve the operator training. (author). 5 refs

358

Ratchet effects in two-dimensional systems with a lateral periodic potential  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Radiation-induced ratchet electric currents have been studied theoretically in graphene with a periodic noncentrosymmetric lateral potential. The ratchet current generated under normal incidence is shown to consist of two contributions, one of them being polarization-independent and proportional to the energy relaxation time, and another controlled solely by elastic scattering processes and sensitive to both the linear and circular polarization of radiation. Two realistic me...

Nalitov, A. V.; Golub, L. E.; Ivchenko, E. L.

2012-01-01

359

Rigorous derivation of coherent resonant tunneling time and velocity in finite periodic systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The velocity $v_{res}$ of resonant tunneling electrons in finite periodic structures is analytically calculated in two ways. The first method is based on the fact that a transmission of unity leads to a coincidence of all still competing tunneling time definitions. Thus, having an indisputable resonant tunneling time $\\tau_{res},$ we apply the natural definition $v_{res}=L/\\tau_{res}$ to calculate the velocity. For the second method we combine Bloch's theorem with the transf...

Pacher, C.; Boxleitner, W.; Gornik, E.

2004-01-01

360

Chaos in driven Alfvén systems: unstable periodic orbits and chaotic saddles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The chaotic dynamics of Alfvén waves in space plasmas governed by the derivative nonlinear Schrödinger equation, in the low-dimensional limit described by stationary spatial solutions, is studied. A bifurcation diagram is constructed, by varying the driver amplitude, to identify a number of nonlinear dynamical processes including saddle-node bifurcation, boundary crisis, and interior crisis. The roles played by unstable periodic orbits and chaotic saddles in these transitions are analyzed, ...

-l Chian, A. C.; Santana, W. M.; Rempel, E. L.; Borotto, F. A.; Hada, T.; Kamide, Y.

2007-01-01

 
 
 
 
361

Chaos in driven Alfvén systems: unstable periodic orbits and chaotic saddles  

Directory of Open Access Journals (Sweden)

Full Text Available The chaotic dynamics of Alfvén waves in space plasmas governed by the derivative nonlinear Schrödinger equation, in the low-dimensional limit described by stationary spatial solutions, is studied. A bifurcation diagram is constructed, by varying the driver amplitude, to identify a number of nonlinear dynamical processes including saddle-node bifurcation, boundary crisis, and interior crisis. The roles played by unstable periodic orbits and chaotic saddles in these transitions are analyzed, and the conversion from a chaotic saddle to a chaotic attractor in these dynamical processes is demonstrated. In particular, the phenomenon of gap-filling in the chaotic transition from weak chaos to strong chaos via an interior crisis is investigated. A coupling unstable periodic orbit created by an explosion, within the gaps of the chaotic saddles embedded in a chaotic attractor following an interior crisis, is found numerically. The gap-filling unstable periodic orbits are responsible for coupling the banded chaotic saddle (BCS to the surrounding chaotic saddle (SCS, leading to crisis-induced intermittency. The physical relevance of chaos for Alfvén intermittent turbulence observed in the solar wind is discussed.

A. C.-L. Chian

2007-01-01

362

76 FR 5296 - Safety Management System for Part 121 Certificate Holders; Extension of Comment Period  

Science.gov (United States)

...a safety management system (SMS) to improve its...10-15, entitled ``Safety Management Systems for Part 121 Certificate...Station Association, Aircraft Electronics Association...10-15. The Airline Safety and Federal...

2011-01-31

363

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

364

Analysis and Comparison of Greek Parliamentary Electoral Systems of the Period 1974-1999  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An important topic, in electoral studies, is the choice of the electoral system, which will be applied in parliamentary elections, because parliamentary seats distributed to political parties differ when a different system is applied. In this paper we focus on the five latest electoral systems applied in Greek Parliamentary Elections. Each one of them is described and analysed, in detail. Different measures of disproportionality are used in order to evaluate and compare these systems. We prov...

Kalogirou, Aikaterini; Panaretos, John

1999-01-01

365

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

Science.gov (United States)

We present a comparison of methods for treating the electrostatic interactions of finite, isolated systems within periodic boundary conditions (PBCs), within density functional theory (DFT), with particular emphasis on linear-scaling (LS) DFT. Often, PBCs are not physically realistic but are an unavoidable consequence of the choice of basis set and the efficacy of using Fourier transforms to compute the Hartree potential. In such cases the effects of PBCs on the calculations need to be avoided, so that the results obtained represent the open rather than the periodic boundary. The very large systems encountered in LS-DFT make the demands of the supercell approximation for isolated systems more difficult to manage, and we show cases where the open boundary (infinite cell) result cannot be obtained from extrapolation of calculations from periodic cells of increasing size. We discuss, implement, and test three very different approaches for overcoming or circumventing the effects of PBCs: truncation of the Coulomb interaction combined with padding of the simulation cell, approaches based on the minimum image convention, and the explicit use of open boundary conditions (OBCs). We have implemented these approaches in the ONETEP LS-DFT program and applied them to a range of systems, including a polar nanorod and a protein. We compare their accuracy, complexity, and rate of convergence with simulation cell size. We demonstrate that corrective approaches within PBCs can achieve the OBC result more efficiently and accurately than pure OBC approaches.

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

2011-11-01

366

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

367

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

368

Formation of nitrides of group 6 transition metals of the Periodic system  

International Nuclear Information System (INIS)

The article deals with a thermodynamic possibility to form nitrides of the Periodic group 6 metals in different reactions. The formation kinetics of molybdenum and tungsten nitrides is investigated in ammonia flow from powdered metals and their oxides. It is established that the formation kinetics for molybdenum and tungsten nitrides is described by pseudotopokinetic equations and nitride formation is controlled by topochemical processes with surface activation. Kinetic, chemical and X-ray methods were used to determine production cycles of quantitative synthesis of pure molybdenum and tungsten nitrides

369

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

370

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

CERN Document Server

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

Oliveira Damazio, Denis; The ATLAS collaboration

2013-01-01

371

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

CERN Document Server

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

Damazio, D O; The ATLAS collaboration

2013-01-01

372

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

373

Light-guide plate using periodical and single-sized microstructures to create a uniform backlight system.  

Science.gov (United States)

Light-guide plates (LGPs) with aperiodic or size-varied microstructures are widely used in edge-lit light-source backlight systems for their high uniformity. In this Letter we designed a LGP with periodic and single-sized microstructures and analyzed the relationship between the holistic arrangement density of the microstructures and the uniformity. By controlling the holistic arrangement density of the microstructures, the uniformity could also be increased. PMID:22941004

Pan, Jui-Wen; Hu, Ya-Wen

2012-09-01

374

On the periodic coordination of linear stochastic systems. [open-loop and closed-loop feedback optimal control  

Science.gov (United States)

The decentralized stochastic control of a linear dynamic system consisting of several subsystems is considered. A two-level approach is used by the introduction of a coordinator who collects measurements from the local controllers periodically and in return transmits coordinating parameters. Two types of coordination are considered: open-loop feedback and closed loop. The resulting control laws are found to be intuitively attractive.

Chong, C.-Y.; Athans, M.

1975-01-01

375

Time-periodic solutions to the full Navier--Stokes--Fourier system with radiation on the boundary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Navier-Stokes-Fourier system is a well established model for describing the motion of viscous compressible heat-conducting fluids. We study the existence of time-periodic weak solutions and improve the known result in the following sense: we extend the class of pressure functions (i.e. consider lower exponent $\\gamma$) and include also the effect of radiation on the boundary.

Axmann, Simon; Pokorny, Milan

2014-01-01

376

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The examination of morphofunctional features of esophagus, stomach, and duodenum as well as the role of diffusive endocrine system's cells in development of esophagogastroduodenal zone in patients without gallbladder is the purpose of the study. 80 patients with various periods after cholecystectomy and 72 patients with cholelithiasis were examined. Endo-scopic, histological and immuno-histochemical studies were carried out against all examined patients. The amount of epitheliocytes prod...

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

2009-01-01

377

Biophysical probing of Spartina maritima photo-system II changes during prolonged tidal submersion periods.  

Science.gov (United States)

Submergence is one of the major constrains affecting wetland plants, with inevitable impacts on their physiology and productivity. Global warming as a driving force of sea level rise, tend to increase the submersion periods duration. Photosynthesis biophysical probing arise as an important tool to understand the energetics underlying plant feedback to these constrains. As in previous studies with Spartina maritima, there was no inhibition of photosynthetic activity in submerged individuals. Comparing both donor and acceptor sides of the PSII, the first was more severely affected during submersion, driven by the inactivation of the OEC with consequent impairment of the ETC. Although this apparent damage in the PSII donor side, the electron transport per active reaction centre was not substantially affected, indicating that this reduction in the electron flow is accompanied by a proportional increase in the number of active reaction centres. These conditions lead to the accumulation of excessive reducing power, source of damaging ROS, counteracted by efficient energy dissipation processes and anti-oxidant enzymatic defences. This way, S. maritima appears as a well-adapted species with an evident photochemical plasticity towards submersion, allowing it to maintain its photosynthetic activity even during prolonged submersion periods. PMID:24630362

Duarte, B; Santos, D; Marques, J C; Caçador, I

2014-04-01

378

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

379

Bifurcation boundaries of three-frequency quasi-periodic oscillations in discrete-time dynamical system  

Science.gov (United States)

This report presents an extensive investigation of bifurcations of quasi-periodic oscillations based on an analysis of a coupled delayed logistic map. This map generates an invariant two-torus (IT>2) that corresponds to a three-torus in vector fields. We illustrate detailed Lyapunov diagrams and, by observing attractors, derive a quasi-periodic saddle-node (QSN) bifurcation boundary with a precision of 10-9. We derive a stable invariant one-torus (IT>1) and a saddle IT>1, which correspond to a stable two-torus and a saddle two-torus in vector fields, respectively. We confirmed that the QSN bifurcation boundary coincides with a saddle-node bifurcation point of a stable IT>1 and a saddle IT>1. Our major concern in this study is whether the qualitative transition from an IT>1 to an IT>2 via QSN bifurcations includes phase-locking. We prove with a precision of 10-9 that there is no resonance at the bifurcation point.

Kamiyama, Kyohei; Inaba, Naohiko; Sekikawa, Munehisa; Endo, Tetsuro

2014-12-01

380

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

CERN Document Server

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

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

2012-01-01

 
 
 
 
381

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

382

The short-period non-contact binary systems UU Lyn and GR Tau  

International Nuclear Information System (INIS)

Two binary systems UU Lyn and GR Tau are discussed on the basis of BV photoelectric observations and spectroscopic observations which were made between 1980 and 1981 at the Tokyo Astronomical Observatory. The component stars in both systems are found to be still inside their Roche lobes but very close to them. (Auth.)

383

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

384

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

385

Simulations of membranes and other interfacial systems using P2(1) and Pc periodic boundary conditions.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We demonstrate the ease and utility of simulating heterogeneous interfacial systems with P2(1) and Pc periodic boundary conditions which allow, for example, lipids in a membrane to switch leaflets. In preliminary tests, P2(1) was shown to yield equivalent results to P1 in simulations of bulk water, a water/vacuum interface, and pure DPPC bilayers with an equal number of lipids per leaflet; equivalence of Pc and P1 was also demonstrated for the former two systems. P2(1) was further tested in s...

Dolan, Elizabeth A.; Venable, Richard M.; Pastor, Richard W.; Brooks, Bernard R.

2002-01-01

386

Role of staircase potential in the energy spectrum of a periodic system  

Energy Technology Data Exchange (ETDEWEB)

An exhaustive study on the energy spectrum and the wave functions of semiconductor superlattices (SLs) in the presence of saw-tooth potential, step potential and the combined potential has been carried out. The study uses a realistic model for the SL based on the periodic crystal potential of the host crystals. The application of the staircase potential results in the formation of discrete Wannier-Stark ladder (WSL) which is experimentally exploited to achieve quantum cascade laser. The conditions for the WSL in SL has been pointed out. For the purpose of comparison, the effect of these potentials on the energy spectrum and the wave functions has also been reported for a single crystal.

Mahapatra, P.K. [Department of Physics and Technophysics, Vidyasagar University, Midnapore 721102 (India)], E-mail: mahapatrap@yahoo.com; Sinha, S. [Department of Physics and Technophysics, Vidyasagar University, Midnapore 721102 (India)], E-mail: ssinhaphy.vu@gmail.com; Panchadhyayee, P. [Department of Physics and Technophysics, Vidyasagar University, Midnapore 721102 (India); Department of Physics, P.K. College, Contai, Purba Medinipur 721401 (India)], E-mail: ppcontai@gmail.com

2008-10-01

387

Role of staircase potential in the energy spectrum of a periodic system  

International Nuclear Information System (INIS)

An exhaustive study on the energy spectrum and the wave functions of semiconductor superlattices (SLs) in the presence of saw-tooth potential, step potential and the combined potential has been carried out. The study uses a realistic model for the SL based on the periodic crystal potential of the host crystals. The application of the staircase potential results in the formation of discrete Wannier-Stark ladder (WSL) which is experimentally exploited to achieve quantum cascade laser. The conditions for the WSL in SL has been pointed out. For the purpose of comparison, the effect of these potentials on the energy spectrum and the wave functions has also been reported for a single crystal

388

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

International Nuclear Information System (INIS)

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

389

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

Science.gov (United States)

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

Chirtoc, M.

2010-03-01

390

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

Energy Technology Data Exchange (ETDEWEB)

The salient features of periodically modulated photoacoustic (PA), photothermal radiometry (PTR) and photopyroelectric (PPE) methods are reviewed with emphasis on their use for characterization of layered samples. Using a general one-dimensional (1-D) heat diffusion model, explicit solutions for up to six layers are given in terms of thermal impedances. Two typical model configurations can be transformed and combined using symmetry properties in order to match a particular excitation/cell configuration couple. Different special cases allow for simultaneous measurement of two thermal parameters. For temperature-dependent investigations the direct temperature-conversion feature of the PPE method is advantageous. We show results on the temperature calibration of LiTaO{sub 3} and PVDF pyroelectric sensors.

Chirtoc, M, E-mail: mihai.chirtoc@univ-reims.f [Equipe de Caracterisation Thermophysique Mutiechelle, GRESPI-ECATHERM, University Reims Champagne Ardenne URCA, BP 1039, 51687 Reims (France)

2010-03-01

391

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 EF, similar in width to f-states in Ce and U compounds, but differing in that cross-section behavior of the near-EF feature suggests substantial 6D admixture

392

A meeting of two chronobiological systems: circadian proteins Period1 and BMAL1 modulate the human hair cycle clock.  

Science.gov (United States)

The hair follicle (HF) is a continuously remodeled mini organ that cycles between growth (anagen), regression (catagen), and relative quiescence (telogen). As the anagen-to-catagen transformation of microdissected human scalp HFs can be observed in organ culture, it permits the study of the unknown controls of autonomous, rhythmic tissue remodeling of the HF, which intersects developmental, chronobiological, and growth-regulatory mechanisms. The hypothesis that the peripheral clock system is involved in hair cycle control, i.e., the anagen-to-catagen transformation, was tested. Here we show that in the absence of central clock influences, isolated, organ-cultured human HFs show circadian changes in the gene and protein expression of core clock genes (CLOCK, BMAL1, and Period1) and clock-controlled genes (c-Myc, NR1D1, and CDKN1A), with Period1 expression being hair cycle dependent. Knockdown of either BMAL1 or Period1 in human anagen HFs significantly prolonged anagen. This provides evidence that peripheral core clock genes modulate human HF cycling and are an integral component of the human hair cycle clock. Specifically, our study identifies BMAL1 and Period1 as potential therapeutic targets for modulating human hair growth. PMID:24005054

Al-Nuaimi, Yusur; Hardman, Jonathan A; Bíró, Tamás; Haslam, Iain S; Philpott, Michael P; Tóth, Balázs I; Farjo, Nilofer; Farjo, Bessam; Baier, Gerold; Watson, Rachel E B; Grimaldi, Benedetto; Kloepper, Jennifer E; Paus, Ralf

2014-03-01

393

The Langevin Hull: Constant pressure and temperature dynamics for non-periodic systems.  

Science.gov (United States)

We have developed a new isobaric-isothermal (NPT) algorithm which applies an external pressure to the facets comprising the convex hull surrounding the system. A Langevin thermostat is also applied to the facets to mimic contact with an external heat bath. This new method, the "Langevin Hull", can handle heterogeneous mixtures of materials with different compressibilities. These systems are problematic for traditional affine transform methods. The Langevin Hull does not suffer from the edge effects of boundary potential methods, and allows realistic treatment of both external pressure and thermal conductivity due to the presence of an implicit solvent. We apply this method to several different systems including bare metal nanoparticles, nanoparticles in an explicit solvent, as well as clusters of liquid water. The predicted mechanical properties of these systems are in good agreement with experimental data and previous simulation work. PMID:21547015

Vardeman, Charles F; Stocker, Kelsey M; Gezelter, J Daniel

2011-04-12

394

The Langevin Hull: Constant pressure and temperature dynamics for non-periodic systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have developed a new isobaric-isothermal (NPT) algorithm which applies an external pressure to the facets comprising the convex hull surrounding the system. A Langevin thermostat is also applied to the facets to mimic contact with an external heat bath. This new method, the “Langevin Hull”, can handle heterogeneous mixtures of materials with different compressibilities. These systems are problematic for traditional affine transform methods. The Langevin Hull does not suffer from the ed...

Vardeman, Charles F.; Stocker, Kelsey M.; Gezelter, J. Daniel

2011-01-01

395

Microwave periodic structures based on MicroElectroMechanical Systems (MEMS) and micromachining techniques  

Digital Repository Infrastructure Vision for European Research (DRIVER)

As a result of the ever growing number of functionalities and standards to be supported by communication systems, as well as the constant development of radar and imaging technologies, a key research area in the field of microwaves and millimeter waves is the achievement of reconfigurability capabilities. In recent years, the progress of MicroElectroMechanical Systems (MEMS) fabrication techniques has allowed radically challenging the performances of reconfigurable devices based on establishe...

Perruisseau-carrier, Julien

2007-01-01

396

Periodic pattern formation in reaction-diffusion systems: an introduction for numerical simulation.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of the present review is to provide a comprehensive explanation of Turing reaction-diffusion systems in sufficient detail to allow readers to perform numerical calculations themselves. The reaction-diffusion model is widely studied in the field of mathematical biology, serves as a powerful paradigm model for self-organization and is beginning to be applied to actual experimental systems in developmental biology. Despite the increase in current interest, the model is not well understoo...

Miura, T.; Maini, Pk

2004-01-01

397

Analysis of reactor coolant pump transient performance in primary coolant system during start-up period  

International Nuclear Information System (INIS)

Highlights: ? Relationships between pump heads and the parameters of a system are established. ? Relationships between pump torques and the parameters of a system are established. ? The variables are non-dimensionlized in order to design a new system and pump. ? All variables are solved analytically. Pump characteristics are not required. ? Mechanism of reactor coolant pump start-up is mathematically solved and clarified. - Abstract: The reactor coolant pump is “the heart” of a nuclear reactor and the only high-speed revolving equipment in a pressurized water reactor primary cooling loop system. The accurate prediction of flow and pump transient performance, during start-up transients, is a very important factor in the reactor coolant pumps design and the nuclear reactor design. Based on the momentum conservation equation of the primary coolant and the moment balance relation of the reactor coolant pump, the transient pump total head, the acceleration head and the overcoming friction head during a pump start up are derived. The relationship between the above heads and the parameters of the system fluid and pump is established too. Furthermore, the transient torques during a pump start-up are also derived. They include the torques required to accelerate the coolant fluid, to accelerate the pump rotating parts and to overcome friction of coolant fluid in the pipes system. The relation between the above three transient torques and the parameters of the coolant fluid and the pump is respectively established. In addition, the above variables are all non-dimensionlized in order to design a new system. The transient flow rate and pump speed are solved analytically. The detailed information of the centrifugal pump characteristics is not required. The analytical non-dimensional flow rate, the pump speed, heads and torques are all affected by an energy ratio ?. The effects of ? on the three transient heads and the three transient torques are discussed respectively. A comparison with Tsukamoto’s experimental results, during the pump start-up, shows an excellent agreement

398

Wavefunction-based method for excited-state electron correlations in periodic systems - application to polymers  

CERN Document Server

A systematic method for determining correlated wavefunctions of extended systems in the ground and excited states is presented. It allows to fully exploit the power of quantum-chemical programs designed for correlation calculations of finite molecules. Using localized Hartree-Fock (HF) orbitals (both occupied and virtual ones), an effective Hamiltonian which can easily be transferred from finite to infinite systems is built up. Correlation corrections to the matrix elements of the effective Hamiltonian are derived from clusters. To treat correlation effects, multireference configuration interaction (MRCI) calculations with singly and doubly excited configurations (SD) are performed. This way one is able to generate both valence and conduction bands where all correlation effects in the excited states as well as in the ground state of the system are taken into account. An appropriate size-extensivity correction to the MRCI(SD) correlation energies is developed which takes into account the open-shell character o...

Bezugly, V

2004-01-01

399

Upregulation of cardiac NO/NOS system during short-term hypoxia and the subsequent reoxygenation period  

Directory of Open Access Journals (Sweden)

Full Text Available Hypoxia/reoxygenation (H/R reportedly influences nitric oxide (NO production and NO synthase (NOS expression in the heart. Nonetheless, a number of works have shown controversial results regarding the changes that the cardiac NO/NOS system undergoes under such situations. Therefore, this study aims to clarify the behaviour of this system in the hypoxic heart by investigating seven different reoxygenation times. Wistar rats were submitted to H/R (hypoxia for 30 min; reoxygenation of 0, 2, 12, 24, 48, 72 h, and 5 days in a novel approach to address the events provoked by assaults under such circumstances. Endothelial and inducible NOS (eNOS and iNOS mRNA and protein expression, as well as enzymatic activity and enzyme location were determined. NO levels were indirectly quantified as nitrate/nitrite, and other S-nitroso compounds (NOx, which would act as NO-storage molecules. The results showed a significant increase in eNOS mRNA, protein and activity, as well as in NOx levels immediately after hypoxia, while iNOS protein and activity were induced throughout the reoxygenation period. These findings indicate that, not only short-term hypoxia, but also the subsequent reoxygenation period upregulate cardiac NO/NOS system until at least 5 days after the hypoxic stimulus, implying major involvement of this system in the changes occurring in the heart in response to H/R.

A. Rus

2011-05-01

400

System size dependence of the log-periodic oscillations of transverse momentum spectra  

CERN Document Server

Recently the inclusive transverse momentum distributions of primary charged particles were measured for different centralities in $Pb+Pb$ collisions. A strong suppression of the nuclear modification factor in central collisions around $p_T \\sim 6-7$ GeV/c was seen. As a possible explanation, the hydrodynamic description of the collision process was tentatively proposed. However, such effect, (albeit much weaker) also exists in the ratio of data/fits, both in nuclear $Pb+Pb$ collisions, and in the elementary $p+p$ data in the same range of transverse momenta for which such an explanation is doubtful. As shown recently, in this case, assuming that this effect is genuine, it can be attributed to a specific modification of a quasi-power like formula usually used to describe such $p_T$ data, namely the Tsallis distribution. Following examples from other branches of physics, one simply has to allow for the power index becoming a complex number. This results in specific log-periodic oscillations dressing the usual p...

Rybczynski, Maciej; Wlodarczyk, Zbigniew

2014-01-01

 
 
 
 
401

GSC 2314-0530: the shortest-period eclipsing system with dMe components  

CERN Document Server

CCD photometric observations in VRI colors and spectroscopic observations of the newly discovered eclipsing binary GSC 2314-0530 (NSVS 6550671) with dMe components and very short period of P=0.192636 days are presented. The simultaneous light-curve solution and radial velocity solution allows to determine the global parameters of GSC 2314-0530: T_{1}=3735 K; T_{2}=3106 K; M_{1}=0.51 M_sun; M_{2}=0.26 M_sun; R_{1}=0.55 R_sun; R_{2}=0.29 R_sun; L_{1}=0.053 L_sun; L_{2}=0.007 L_sun; i=72.5 degr; a=1.28 R_sun; d=59 pc. The chromospheric activity of its components is revealed by strong emission in the H_alpha line (with mean EW=5 A) and observed several flares. Empirical relations mass-M_{bol}, mass-radius and mass-temperature are derived on the basis of the parameters of known binaries with low-mass dM components.

Dimitrov, D

2010-01-01

402

Galilean invariance in confined quantum systems: implications for spectral gaps, superfluid flow, and periodic order.  

Science.gov (United States)

Galilean invariance leaves its imprint on the energy spectrum and eigenstates of N quantum particles, bosons, or fermions, confined in a bounded domain. It endows the spectrum with a recurrent structure, which in capillaries or elongated traps of length L and cross-section area s(?) leads to spectral gaps n(2)h(2)s(?)?/(2 mL) at wave numbers 2n?s(?)?, where ? is the number density and m is the particle mass. In zero temperature superfluids, in toroidal geometries, it causes the quantization of the flow velocity with the quantum h/(mL) or that of the circulation along the toroid with the known quantum h/m. Adding a "friction" potential, which breaks Galilean invariance, the Hamiltonian can have a superfluid ground state at low flow velocities but not above a critical velocity, which may be different from the velocity of sound. In the limit of infinite N and L, if N/L = s(?)? is kept fixed, translation invariance is broken, and the center of mass has a periodic distribution, while superfluidity persists at low flow velocities. This conclusion holds for the Lieb-Liniger model. PMID:24655263

Süt?, András

2014-03-01

403

The Earth-Moon system during the Late Heavy Bombardment period  

CERN Document Server

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

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

2009-01-01

404

18 CFR 301.4 - Exchange Period Average System Cost determination.  

Science.gov (United States)

...Construction, Distribution Plant. (iv) CONSTANT...base the costs of power products purchased...total Contract System Load. ...sales for resale and power purchases —(1) Long-term and intermediate-term sales for...allowed to include new plant additions,...

2010-04-01

405

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

Directory of Open Access Journals (Sweden)

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

Dwijen Rudrapal,

2011-05-01

406

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

International Nuclear Information System (INIS)

Proton magnetic resonance spectroscopic, vapor pressure osmometric and Karl Fischer titrimetric measurements have provided support for our earlier findings obtained from interfacial tension and mass transfer experiments that reversed micelles are formed, under certain conditions, in the system HDEHP/n-hexane/CaCl2 solution. These studies were further extended to include different organophosphorus acid (PC 88A), diluent (benzene), and metal ions (Co2+, Ni2+, and Zn2+) to determine whether reversed micellization is a general phenomenon occurring in solvent extraction systems which employ organophosphorus acids. The data obtained so far, suggest that reversed micellization indeed is a general phenomenon operative in organophosphorus acid extractant systems. A new mass transfer cell has been constructed in order to investigate the metal distribution equilibria and extraction kinetics of Co, Ni and Zn using atomic absorption spectrophotometric technique. A quasi-elastic light-scattering apparatus has been installed to investigate aggregation phenomena in solvent extraction systems. Preliminary drop-interface coalescence studies were performed, and the results were correlated with those obtained from interfacial tension measurements. The laser heterodyne light-scattering apparatus for measurement of interfacial viscoelastic properties also has been set-up and is being optimized for high resolution measurements. 21 refs., 16 figs

407

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

Energy Technology Data Exchange (ETDEWEB)

We consider classical and quantum propagators for two different time intervals. If these propagators follow one another in a Fibonacci sequence we get a discrete quasi-periodic system. A theorem due to Nielsen provides a novel conserved quantity for this system. The Nielsen quantity controls the transition between commutative and non-commutative propagation in time. The quasi-periodically kicked oscillator, moreover, is dominated by quasi-periodic analogues of the Floquet theorem.

Kramer, P [Theoretische Physik, University Tuebingen (Germany); Kramer, T [Institute for Theoretical Physics, University Regensburg (Germany); Man' ko, V I [Lebedev Physical Institute, Moscow (Russian Federation)], E-mail: peter.kramer@uni-tuebingen.de

2009-05-15

408

Automated System of Study Nonlinear Processes in Electro-vacuum Devices with Open Resonant Periodic Structures  

Directory of Open Access Journals (Sweden)

Full Text Available The article describes the experimental equipment and the results of investigations of nonlinear processes occurring during the excitation of electromagnetic oscillations in the resonant electron beam devices such as an orotron-generator of diffraction radiation. These devices are finding wide application in physics and microwave technology, now. A technique for experimental research, which bases on the using of the universal electro vacuum equipment diffraction radiation analyzer and the microprocessor system for collecting and processing data. The experimental investigations results of the energy and frequency characteristics for the most common modes of the excitation oscillations in the open resonant systems such as an orotron. The implementations on the optimum modes for the oscillations excitation in such devices were recommended.

G.S. Vorobyov

2014-04-01

409

Properties of stationary nonequilibrium states in the thermostatted periodic Lorentz gas: the multiparticle system.  

Science.gov (United States)

We study the stationary nonequilibrium states of N-point particles moving under the influence of an electric field E among fixed obstacles (disk) in a two-dimensional torus. The total kinetic energy of the system is kept constant through a Gaussian thermostat that produces a velocity dependent mean field interaction between the particles. The current and the particle distribution functions are obtained numerically and compared for small /E/ with analytic solutions of a Boltzmann-type equation obtained by treating the collisions with the obstacles as random independent scatterings. The agreement is surprisingly good for both small and large N. The latter system in turn agrees with a self-consistent one-particle evolution expected to hold in the N-->infinity limit. PMID:12059542

Bonetto, F; Daems, D; Lebowitz, J L; Ricci, V

2002-05-01

410

The Effects of Quercetin and Retinoic acid on Skeletal System of Rat Embryos in Prenatal Period  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: Prenatal rat embryo exposure to retinoid induces some malformations in various organs, the most active and teratogenic metablolite is all-trans-retinoic acid (atRA). The teratogenic effects of some drugs can be prevented by the application of antioxidant drugs and stimulation of the maternal immune system. Also, quercetin, a naturally occurring flavonoid has excellent antioxidant properties. Therefore, in this study, the prophylactic effect of quercetin on teratogenic effects of a...

Nahid Gohari-Behbahani; Mahmood Khaksary-Mahabady; Reza Ranjbar; Hossein Najafzadeh-Varzi; Babak Mohammadian Department Of Pathology, Faculty Of Veterinary Medicine

2014-01-01

411

Assessment of financial flow in the health system of Serbia in a period 2003-2006  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background/Aim. The main goal of every health policy is not merely the establishment of the health system sustainability, but the accessibility of health services to the whole population, as well. This objective is shared in European Union countries, and the consequence is the implementation of National Health Accounts (NHA). NHA, as a tool for evidence-based management, provides data regarding financial flow in health at national level and alows international comparability. The aim of this s...

Gaji?-Stevanovi? Milena; Teodorovi? Nevenka; Dimitrijevi? Snežana; Jovanovi? Dragan

2010-01-01

412

Measuring and decomposing the overall efficiency of multi-period and -division systems associated with DEA  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The combination way of component efficiencies into the overall efficiency is a central topic in the efficiency modeling of network systems based on data envelopment analysis (DEA). In terms of the feature and advantage of DEA modeling as the multiplier generation on inputs/outputs, it is desirable that the combination weights are derived from the data and self-generated in calculation process. The prior weights choice makes DEA modeling lose the objectivity and generalization in efficiency me...

Chen, Kaihua

2014-01-01

413

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

International Nuclear Information System (INIS)

It is of utmost importance to have a computer code in order to analyze how different parameters (like test duration time) affect the unavailability of safety systems of nuclear. In this context, a study was performed in order to evaluate the model employed by the FRANTIC computer code, which performs detailed calculations on the contribution to the system unavailability originated by hardware failures, component tests and repairs, aiming at considering the influence of different test schemes on the system unavailability. It was shown, by means of the results attained that the numerical model used by the FRANTIC code and the analytical model proposed by APOSTOLAKIS and CHU (4) give unavailability values much similar when the component tests are supposed to be perfect. When a test is supposed to be imperfect (that is, when it may induce a test is supposed to be imperfect (that is, when it may induce a failure on the component being tested), the analytical model presents more conservative results. (author)

414

A periodic Energy Decomposition Analysis (pEDA) method for the Investigation of Chemical Bonding in Extended Systems  

CERN Document Server

The development and first applications of a new periodic energy decomposition analysis (pEDA) scheme for extended systems based on the Kohn-Sham approach to density functional theory are described. The pEDA decomposes the binding energy between two fragments (e.g. the adsorption energy of a molecule on a surface) into several well-defined terms: preparation, electrostatic and dispersion interaction, Pauli repulsion and orbital relaxation energies. The pEDA presented here for an AO-based implementation can handle restricted and unrestricted fragments for 0D to 3D systems considering periodic boundary conditions with and without the determination of fragment occupations. For the latter case, reciprocal space sampling is enabled. The new method gives comparable results to established schemes for molecular systems and shows good convergence with respect to the basis set (TZ2P), the integration accuracy and k-space sampling. Four typical bonding scenarios for surface adsorbate complexes were chosen to highlight th...

Raupach, Marc

2015-01-01

415

RESEARCHES REGARDING THE TECHNOLOGICAL PERFORMANCES OF CARP REARING DURING WINTER PERIOD IN THE CONDITIONS OF A RECIRCULATING AQUACULTURE SYSTEM  

Directory of Open Access Journals (Sweden)

Full Text Available The techniques of carp culture are highly diversified, ranging from the extensive production in pond or open water with no fertilization or supplemental feeding to highly intensive systems in concrete tanks or cages. Among the different carp species, common carp is the best species reared in intensive monoculture, the others (Chinese and Indian carps being usually cultivated in polyculture (P. Kestemont, 1995. An experiment was conducted in inside recirculation system conditions to identify the technological performances on carp growth and survival at the Fishing and Aquaculture Department, Galati, during winter period (February, 2007 – March, 2007. The 1-year-old carp (Cyprinus carpio 4792g; 4594 g; 4561 g and 4525 g (total weight grew to 7384g; 7017g; 6924g and 7125 g in 44 days in aquarium 1, 2, 3 and 4, respectively. In all aquariums, the fish appeared healthy and no mortality was observed. Feed conversion efficiencies (FCE had similar values among all aquariums, the highest FCE being found in B4 aquarium with 1, 57 value. Water quality parameters were acceptable range for fish culture. Results show that the carp rearing during winter period in the inside recirculation system is a very good economic solution.

G. STEFAN

2013-12-01

416

The BVRI Light Curves And Period Analysis Of The Beta Lyrae System XX Leonis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The contact eclipsing binary system XX Leonis (P = 0.97 days, sp A8) has been analysed using the PHOEBE programme, based on the Wilson Devinney code. The BVRI light curves were obtained during spring 2006 using the 20-cm telescope and ST-7 CCD detector. The effective temperature of the primary component determined from the photometric analysis is T=(7889+/-61)K, the inclination of the orbit is i=(89.98+/-2.45)deg and the photometric mass ratio q=(0.41+/-0.01). Also the third...

Zasche, P.; Wolf, M.; Svoboda, P.

2007-01-01

417

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

International Nuclear Information System (INIS)

The conceptual design of an on-line, near-real-time nondestructive assay instrumentation network for the Los Alamos Plutonium Facility is complete. Analysis of instrument history data indicates that the instrument certification procedures need improvement. Analysis of exhaust filter data has led to the derivation of a buildup prediction equation that is a function of throughput. This suggests that development of a generalized model is possible. A number of routine reports are now available from the Plutonium Facility/Los Alamos Safeguards System including inventories and active reports

418

The Rotne-Prager-Yamakawa approximation for periodic systems in a shear flow.  

Science.gov (United States)

Rotne-Prager-Yamakawa approximation is a commonly used approach to model hydrodynamic interactions between particles suspended in fluid. It takes into account all the long-range contributions to the hydrodynamic tensors, with the corrections decaying at least as fast as the inverse fourth power of the interparticle distances, and results in a positive definite mobility matrix, which is fundamental in Brownian dynamics simulations. In this communication, we show how to construct the Rotne-Prager-Yamakawa approximation for the bulk system under shear flow, which is modeled using the Lees-Edwards boundary conditions. PMID:24832249

Mizerski, Krzysztof A; Wajnryb, Eligiusz; Zuk, Pawel J; Szymczak, Piotr

2014-05-14

419

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

International Nuclear Information System (INIS)

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

420

Localized orbital description of electronic structures of extended periodic metals, insulators, and confined systems: Density functional theory calculations  

Science.gov (United States)

We present a simple and general method for construction of localized orbitals to describe an electronic structure of extended periodic metals and insulators as well as confined systems. Spatial decay of these orbitals is found to exhibit exponential behavior for insulators and power law for metals. While these orbitals provide a clear description of bonding, they can be also used to determine polarization of insulators. Within density functional theory, we illustrate applications of this method to crystalline aluminium, copper, silicon, PbTiO3 , and molecules, such as ethane and diborane.

Bhattacharjee, Joydeep; Waghmare, Umesh V.

2006-03-01

 
 
 
 
421

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

Science.gov (United States)

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

Shang, Honghui; Li, Zhenyu; Yang, Jinlong

2011-07-21

422

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

International Nuclear Information System (INIS)

Interfacial behavior of extractant molecules and their interaction with metal ions has been investigated. Consideration was also given to the question of microscopic interfaces, i.e., those associated with reversed micelles as well as microemulsions. NMR spectroscopy, fluorescence spectroscopy, quasi-elastic light scattering, vapor pressure osmometry, and Karl-Fischer titrimetry provided support for findings obtained from interfacial tension experiments that reversed micelles are formed, under certain conditions, in the system di(2-ethylhexyl)phosphoric acid (HDEHP)/ n-hexane/CaCl2 solution. These techniques were further extended to include different organophosphorus acids (PC 88A and CYANEX 272), diluent (benzene), and metal ions (Co2+, Ni2+, and Zn2+) to determine whether reversed micellization occurs in solvent extraction systems which employ organophosphorus acids. A preliminary general model of the aggregation mechanism for metal-extractant complexes has been proposed. Also various laser techniques have been used to investigate the structure and dynamics of extractant films. A laser fluorescence apparatus for probing interfacial dynamics is under construction. 64 refs., 29 figs

423

Rapid supersensitive laser-semiconductor monitoring system. Time period covered: Dec. 15, 1993 - Dec. 15, 1994  

International Nuclear Information System (INIS)

The creation of the rapid and sensitive system for the determination of the Alpha-radioactivity in the Environmental samples has been determined as the main goal of the Research Contract No. 7200RO/RB. As a result of the first stage of the research accomplished in the year 1993, the prototype of the system based on the combination of the laser photoionization mass spectrometry and many-channel alpha-spectrometer has been built and tested. To improve the sensitivity it was proposed to add one more stage to the laser photoionization mass-spectrometer. To develop the high position sensitivity of the system it was proposed to include into the alpha-radiometer SI strip-detector with submicron position sensitivity. Hardware and software for the laser-semiconductor monitoring system of alpha-radionuclides in the environment have been further developed and tested in frames of the IAEA Research Contract No. 7200/R1/RB. Optimization of the sample evaporation with one more stage of photoionization has been successfully performed in the laser photoionization mass-spectrometer. The automatization of the measurement procedure is under way by means of the IBM PC-386 and specially designed electronic units. The evaluated sensitivity of the new set-up is in the range of 1.0 Bq/kg. A bulk measurement of the alpha-radioactivity concentration in soil samples from the Chernobyl region (100 km) have been performed by means of thick samples method and built under this contract alpha-radiometer with large area SI semiconductor detectors. The lowest detectable level was in the range 100 Bq/kg without any radiochemical separation. Comparison with the data obtained for the same probes by means of the thin sample (with radiochemical separation) has shown higher Pu-concentration values obtained by means of the thick samples. For the first time the Sl-strip-detector with 128 channels has been applied for the alpha-radiometry purposes. Different read-out electronics (including the most sophisticated one used in high energy physics experiments) has been studied and tested. The most suitable set (preamplifier, shaper, discriminator) of electronics has been found and built for the test measurements with the 128-channel Sl-strip-detector produced for the purposes of the alpha-radiometry by Kiev firm 'Detector'. The studies have been performed to use for the alpha-radiometry purposes sub-micron position sensitivity of the Sl-strip-detector. Such high accuracy of the position measurements could be useful for some radiobiological applications if the cell level accuracy of the tracer radioactive element position is concerned. Another application of the Sl-strip-detectors for alpha-radiometry purposes could be realized for the detection of the radioactive contamination spots with high position accuracy

424

Quantum phase transition and thermodynamic properties of a fourfold magnetic periodic system  

Science.gov (United States)

Based on the experimental synthesis of organic compound verdazyl radical ?-3-(2,6-dichlorophenyl)-1,5-diphenylverdazyl, consisting of four antiferromagnetic couplings, we study the magnetic properties and thermodynamic behaviors for different antiferromagnetic interactions using Green’s function theory. Under different fields, there are five regimes containing two gapless phases and three magnetization plateaus (M=0, 1/2 and saturated magnetization) distinguished by four critical lines, which are evidenced by the two-site entanglement entropy and closely related to the energy spectra. In addition, we calculate the susceptibility and specific heat, to demonstrate the low-lying excitations at low temperatures. It will provide guidance for us to synthesize varieties of unconventional magnetic materials, and stimulate future studies on quantum spin systems.

Wang, Shuling; Li, Ruixue; Ding, Linjie; Fu, Hua-Hua; Zhu, Si-cong; Ni, Yun; Meng, Yan; Yao, Kailun

2014-12-01

425

Irregular Periods  

Science.gov (United States)

... Date reviewed: October 2013 Back 1 ? 2 For Teens For Kids For Parents MORE ON THIS TOPIC Coping With Common Period Problems I'm 14 and I Don't Have My Period Yet. Is This Normal? Can a Girl Get Pregnant if She Has Sex During Her Period? Birth Control Pill Gyn Checkups ...

426

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

CERN Document Server

Solar arrays are structures which are connected to satellites; during launch, they are in a folded position and submitted to high vibrations. In order to save mass, the flexibility of the panels is not negligible and they may strike each other; this may damage the structure. To prevent this, rubber snubbers are mounted at well chosen points of the structure; a prestress is applied to the snubber; but it is quite difficult to check the amount of prestress and the snubber may act only on one side; they will be modeled as one sided springs (see figure 2). In this article, some analysis for responses (displacements) in both time and frequency domains for a clamped-clamped Euler-Bernoulli beam model with a spring are presented. This spring can be unilateral or bilateral fixed at a point. The mounting (beam +spring) is fixed on a rigid support which has a sinusoidal motion of constant frequency. The system is also studied in the frequency domain by sweeping frequencies between two fixed values, in order to save the...

Hazim, Hamad

2009-01-01

427

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

Science.gov (United States)

Low-mass white-dwarf stars are the remnants of disrupted red-giant stars in binary millisecond pulsars and other exotic binary star systems. Some low-mass white dwarfs cool rapidly, whereas others stay bright for millions of years because of stable fusion in thick surface hydrogen layers. This dichotomy is not well understood, so the potential use of low-mass white dwarfs as independent clocks with which to test the spin-down ages of pulsars or as probes of the extreme environments in which low-mass white dwarfs form cannot fully be exploited. Here we report precise mass and radius measurements for the precursor to a low-mass white dwarf. We find that only models in which this disrupted red-giant star has a thick hydrogen envelope can match the strong constraints provided by our data. Very cool low-mass white dwarfs must therefore have lost their thick hydrogen envelopes by irradiation from pulsar companions or by episodes of unstable hydrogen fusion (shell flashes). We also find that this low-mass white-dwarf precursor is a type of pulsating star not hitherto seen. The observed pulsation frequencies are sensitive to internal processes that determine whether this star will undergo shell flashes. PMID:23803845

Maxted, Pierre F L; Serenelli, Aldo M; Miglio, Andrea; Marsh, Thomas R; Heber, Ulrich; Dhillon, Vikram S; Littlefair, Stuart; Copperwheat, Chris; Smalley, Barry; Breedt, Elmé; Schaffenroth, Veronika

2013-06-27

428

Few period quasisymmetric stellarators  

Energy Technology Data Exchange (ETDEWEB)

The results of plasma equilibrium and local stability investigations in two and four-period quasisymmetric stellarators are presented. A near-axis approximation is used for 2-period systems and the 3D codes VMEC and TERPSICHORE are used for four-periods devices to optimise the configurations. (author) 4 figs., 8 refs.

Isaev, M.Y.; Mikhailov, M.I.; Shafranov, V.D.; Subbotin, A.A. [Russian Research Centre `Kurchatov Institute`, Moscow (Russian Federation); Cooper, W.A. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP); Medvedev, S.Y. [Keldysh Inst. of Applied Mathematics, Russian Academy of Sciences, Moscow (Russian Federation)

1997-06-01

429

Study of short-period RS Canum Venaticorum and W Ursae Majoris binary systems: The global nature of H?  

International Nuclear Information System (INIS)

I present the rotation versus emission characteristics of the H? line for several short-period (P-5) and the Rossby number (the ratio between the rotational period and the convective time scale) is seen for those components showing emission. Such a correlation suggests that the H? line is a good diagnostic for the study of the magnetic-related activity in late-type stellar systems. Plotting the L/sub Halpha//L/sub bol/ against a measure of the tidal amplitude of Scharlemann shows that the activity of the W UMa secondary components may be shut off by the tidal forces of the primaries. The shut-off appears in those components having a tidal amplitude > or approx. =0.02. It is, however, unclear whether the tidal damping of the diffe whether the tidal damping of the differential rotation is the sole mechanism responsible for the shut-off of the H? emission, as the activity damping may also be attributable to the contact nature of the W UMa systems

430

Masses and Radii of Low-Mass Companions in Short Period Eclipsing Binary Systems Selected from STEREO Data  

Science.gov (United States)

As part of our project for studying bright (V light curves extracted from STEREO photometry, wide coverage Echelle spectra obtained at Apache Point Observatory for stellar characterization and Coude spectra obtained at NAO Rozhen for radial velocity curves. Here we present physical parameters for six short period (p light curves, the RV curves, and the Echelle spectra, makes it possible to determine the masses and radii of individual components. The second method relies on modeling the binary systems with the Wilson-Devinney code. Basic parameters measured from the light curves (period, radii ratio) and RV curves (amplitude, eccentricity) are fixed and used to feed the code. This helps to reduce the number of free parameters and to fully utilize the available information. A complete simultaneous solution is obtained that includes orbital elements of the binary systems along with fundamental parameters such as masses and radii of both components. We compare the results from the two approaches and discuss the uncertainties and caveats in each of the two methods.

Tsvetanov, Zlatan I.; Markov, H.; Belcheva, M.; Iliev, I.; Stateva, I.

2014-01-01

431

Brownian dynamics of double-stranded DNA in periodic systems with discrete salt  

Science.gov (United States)

Numerical models of mesoscale DNA dynamics relevant to in vivo scenarios require methods that incorporate important features of the intracellular environment, while maintaining computational tractability. Because the explicit inclusion of ions leads to electrostatic calculations that scale as the square of the number of charged particles, such models typically handle these calculations using low-potential, mean-field approaches, rather than by considering the discrete interactions of ions. This allows approximation of the long-range, screened self-repulsion of DNA, but is unable to capture detailed electrostatic phenomena, such as short-range attractions mediated by ion-ion correlations. Here, we develop a dynamical model of explicitly double-stranded, sequence-specific DNA in a bulk environment consisting of other polyions and explicitly represented counterions and coions. DNA is represented as two interwound chains of charged Stokes spheres, and ions as free, monovalently charged Stokes spheres. Brownian dynamics simulations performed at salt concentrations of 0.1, 1, 10, and 100 mM demonstrate this model captures anticipated behaviors of the system, including increasing compaction of the polyion by the ionic atmosphere with increasing ionic strength. The decay of the distance dependence of the ion concentrations as one moves away from the polyion approaches their equilibrium values in quantitative agreement with predictions of Poisson-Boltzmann theory. The simulation results also demonstrate quantitative agreement with experimental measurements of the persistence length of B-DNA, which increases significantly at low ionic strengths. The model also captures behaviors intimating the importance of explicitly representing ionic and polyionic structure. These include penetration of the polyion interior by both coions and counterions, and counterion-mediated accumulation of coions near the surface of the polyion. Such phenomena are likely to play an important role in the formation of alternative DNA secondary structures, suggesting the present methods will prove valuable to dynamic models of superhelical stress-induced DNA structural transitions.

Mielke, Steven P.; Grønbech-Jensen, Niels; Benham, Craig J.

2008-03-01

432

The Effects of Quercetin and Retinoic acid on Skeletal System of Rat Embryos in Prenatal Period  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Prenatal rat embryo exposure to retinoid induces some malformations in various organs, the most active and teratogenic metablolite is all-trans-retinoic acid (atRA. The teratogenic effects of some drugs can be prevented by the application of antioxidant drugs and stimulation of the maternal immune system. Also, quercetin, a naturally occurring flavonoid has excellent antioxidant properties. Therefore, in this study, the prophylactic effect of quercetin on teratogenic effects of atRA was evaluated. Materials and Methods: In this experimental study, 40 pregnant rats were divided into 7 groups. Control group received normal saline and test groups received dimethylsulfoxide (DMSO, quercetin (75 mg/kg, quercetin (200 mg/kg, atRA (25 mg/kg, atRA (25 mg/kg plus quercetin (75 mg/kg and atRA (25 mg/kg plus quercetin (200 mg/kg, intraperitoneally at 8-10th days of gestation. Fetuses were collected at 20th day of gestation and after determination of weight and length; they were stained by Alizarin red-Alcian blue method. Results: Cleft palate, exencephaly and spina bifida incidence were 30.76%, 61.53% and 30.76% range in group which received only atRA. Cleft palate, exencephaly and spina bifida incidence were 11.11%, 16.66% and 5.55% in group which received atRA plus quercetin (75 mg/kg. However, cleft palate, exencephaly and spina bifida incidence were 10.52%, 10.52% and 0% in group which received atRA plus quercetin (200 mg/kg. The means of weight and length of fetuses from rat that received atRA plus quercetin (75 mg/kg were significantly greater than those received only atRA. Conclusion: It is concluded that quercetin decreased teratogenicity induced by atRA, but this subject needs more detailed evaluation.

Nahid Gohari-Behbahani

2014-12-01

433

Investor's requirements on software of operating diagnostic system in period of nuclear power unit start-up  

International Nuclear Information System (INIS)

The demands are summed up on the software for the diagnostic system of the Dukovany nuclear power plant in the period of the integrated hydraulic trial, the physical and power start-up of the unit. These demands have followed from experience gained with the first and second units of the plant which showed that it was very difficult to locate, using the installed diagnostic system, the source of the failure by analyzing an arbitrary signal from the sensor output. The functions are defined which the diagnostic system software must fulfil during the start-up when it is necessary to detect defects of delivered components including defects of assembly such as to allow their removal during the revision of the installation. Special attention is devoted to the identification of loose parts in the primary circuit and to the possibility of calibrating and simulating the system of loose parts in operation. The software of the system must proceed from an estimate of weight and kinetic energy of the loose part which must be identified, including the distance between the point of impact and the sensor, and the time of contact of the part with the point of impact. (Z.M.)

434

Assessment of transport parameters in a karst system under various flow periods through extensive analysis of artificial tracer tests  

Science.gov (United States)

It is primordial to understand the sensibility of a catchment or a spring against contamination to secure a sustainable water resource management in karst aquifers. Artificial tracer tests have proven to be excellent tools for the simulation of contaminant transport within an aquifer before its arrival at a karst spring as they provide information about transit times, dispersivities and therefore insights into the vulnerability of a water body against contamination (Geyer et al. 2007). For this purpose, extensive analysis of artificial tracer tests was undertaken in the following work, in order to acquire conservative transport parameters along fast and slow pathways in a mature karst system under various flow conditions. In the framework of the project "Protection of Jeita Spring" (BGR), about 30 tracer tests were conducted on the catchment area of the Jeita spring in Lebanon (Q= 1 to 20 m3/s) under various flow conditions and with different injection points (dolines, sinkholes, subsurface, and underground channel). Tracer breakthrough curves (TBC) observed at karst springs and in the conduit system were analyzed using the two-region non-equilibrium approach (2NREM) (Toride & van Genuchten 1999). The approach accounts for the skewness in the TBCs long tailings, which cannot be described with one dimensional advective-dispersive transport models (Geyer et al. 2007). Relationships between the modeling parameters estimated from the TBC were established under various flow periods. Rating curves for velocity and discharge show that the flow velocity increases with spring discharge. The calibrated portion of the immobile region in the conduit system is relatively low. Estimated longitudinal dispersivities in the conduit system range between 7 and 10 m in high flow periods and decreases linearly with increasing flow. In low flow periods, this relationship doesn't hold true as longitudinal dispersivities range randomly between 4 and 7 m. The longitudinal dispersivity decreases with increasing flow rates because of the increase of advection control over dispersion and increasing dilution. Therefore variance of the TBC is controlled on the hand by dispersivity during high flow periods and on the other hand by increasing mobile phase in low flow periods due to an increase of the portion of immobile zones (pools and ripples) as water level decreases. For tracer tests with injection points at the surface, longitudinal dispersivities are found to be of higher ranges (8-27 m) and highly reflective of the compartments in which the tracer is flowing (unsaturated rock matrix, conduits or channel). The comparison of tracer tests with different injection points shows clearly that the tailing observed in some of the breakthrough curves is mainly generated in the unsaturated zone before the tracer arrives to the main channel draining the system and decreases gradually within the channel. Geyer, T. , Birk S., Licha T., Liedl R., Sauter M. (2007): Multitracer Approach to Characterize Reactive Transport in Karst Aquifers. Groundwater, Vol. 35, No 1. 35-45. Toride, N., Leij, F.J., van Genuchten, M.T., 1999. The CXTFIT code (version 2.1) for estimating transport parameters from laboratory or field tracer experiments. U.S. Salinity Laboratory Agricultural Research Service, U.S. Department of Agriculture Riverside, California. Research Report 137.

Doummar, J.; Margane, A.; Sauter, M.; Geyer, T.

2012-04-01

435

Mendeleev-2013. VII All-Russian conference of young scientists, postgraduate students and students with international participation on chemistry and nanomaterials. Book of abstracts. Section 5. Physical chemistry  

International Nuclear Information System (INIS)

VII All-Russian conference of young scientists, postgraduate students and students with international participation on chemistry and nanomaterials was conducted on the Chemistry department of Saint-Petersburg State University on April, 2-5, 2013. In the conference participants from 14 countries took part. There were five sections: Nanochemistry and nanomaterials, Analytic chemistry, Inorganic chemistry, Organic chemistry, Physical chemistry. In the collection (Section 5 - Physical chemistry) there are abstracts concerning the investigations of physico-chemical properties and structure of various materials: composites on the base of polymers and fullerenes, as well as catalysts, ion-exchange membranes, sorbents etc.; phase studies of different systems, rare earth elements among them; development of physico-chemical determination methods of biological active compounds, and many other problems

436

A Fortran 90 Hartree-Fock program for one-dimensional periodic ?-conjugated systems using Pariser-Parr-Pople model  

Science.gov (United States)

Pariser-Parr-Pople (P-P-P) model Hamiltonian is employed frequently to study the electronic structure and optical properties of ?-conjugated systems. In this paper we describe a Fortran 90 computer program which uses the P-P-P model Hamiltonian to solve the Hartree-Fock (HF) equation for infinitely long, one-dimensional, periodic, ?-electron systems. The code is capable of computing the band structure, as also the linear optical absorption spectrum, by using the tight-binding and the HF methods. Furthermore, using our program the user can solve the HF equation in the presence of a finite external electric field, thereby, allowing the simulation of gated systems. We apply our code to compute various properties of polymers such as trans-polyacetylene, poly- para-phenylene, and armchair and zigzag graphene nanoribbons, in the infinite length limit. Program summaryProgram title: ppp_bulk.x Catalogue identifier: AEKW_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKW_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 87 464 No. of bytes in distributed program, including test data, etc.: 2 046 933 Distribution format: tar.gz Programming language: Fortran 90 Computer: PCs and workstations Operating system: Linux, Code was developed and tested on various recent versions of 64-bit Fedora including Fedora 14 (kernel version 2.6.35.12-90). Classification: 7.3 External routines: This program needs to link with LAPACK/BLAS libraries compiled with the same compiler as the program. For the Intel Fortran Compiler we used the ACML library version 4.4.0, while for the gfortran compiler we used the libraries supplied with the Fedora distribution. Nature of problem: The electronic structure of one-dimensional periodic ?-conjugated systems is an intense area of research at present because of the tremendous interest in the physics of conjugated polymers and graphene nanoribbons. The computer program described in this paper provides an efficient way of solving the Hartree-Fock equations for such systems within the P-P-P model. In addition to the Bloch orbitals, band structure, and the density of states, the program can also compute quantities such as the linear absorption spectrum, and the electro-absorption spectrum of these systems. Solution method: For a one-dimensional periodic ?-conjugated system lying in the xy-plane, the single-particle Bloch orbitals are expressed as linear combinations of p-orbitals of individual atoms. Then using various parameters defining the P-P-P Hamiltonian, the Hartree-Fock equations are set up as a matrix eigenvalue problem in the k-space. Thereby, its solutions are obtained in a self-consistent manner, using the iterative diagonalizing technique at several k points. The band structure and the corresponding Bloch orbitals thus obtained are used to perform a variety of calculations such as the density of states, linear optical absorption spectrum, electro-absorption spectrum, etc. Running time: Most of the examples provided take only a few seconds to run. For a large system, however, depending on the system size, the run time may be a few minutes to a few hours.

Kondayya, Gundra; Shukla, Alok

2012-03-01

437

IUPAC Periodic Table of Isotopes for the Educational Community  

Energy Technology Data Exchange (ETDEWEB)

John Dalton first proposed the concept of atomic weights of the elements in the first decade of the nineteenth century. These atomic weights of the chemical elements were thought of as constants of nature, similar to the speed of light. Dmitri Mendeleev arranged the atomic weights of the elements in ascending order of value and used the systematic variation of their chemical properties to produce his Periodic Table of the Elements in 1869. Measurement of atomic weight values became an important chemical activity for a century and a half. Theodore Richards received a Noble Prize for his work in this area. In 1913, Fredrick Soddy found a species of radium, which had an atomic weight value of 228, compared to the familiar radium gas value of 226. Soddy coined the term 'isotope' (Greek for 'in the same place') to account for this second atomic weight value in the radium position of the Periodic Table. Both of these isotopes of radium are radioactive. Radioactive isotopes are energetically unstable and will decay (disintegrate) over time. The time it takes for one half of a sample of a given radioactive isotope to decay is the half-life of that isotope. In addition to having different atomic weight values, radium-226 and radium-228 also have different half-life values. Around the same time as Soddy's work, J.J. Thomson (discoverer of the electron) identified two stable (non-radioactive) isotopes of the same element, neon. Over the next 40 years, the majority of the known chemical elements were found to have two or more stable (or long-lived radioactive isotopes that contribute significantly to the determination of the atomic weights of the elements).

Holden N. E.; Holden,N.E.; Coplen,T.B.

2012-07-15

438

Yukawa potentials in systems with partial periodic boundary conditions II : Lekner sums for quasi-two dimensional systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Yukawa potentials may be long ranged when the Debye screening length is large. In computer simulations, such long ranged potentials have to be taken into account with convenient algorithms to avoid systematic bias in the sampling of the phase space. Recently, we have provided Ewald sums for quasi-two dimensional systems with Yukawa interaction potentials [M. Mazars, {\\it J. Chem. Phys.\\/}, {\\bf 126}, 056101 (2007) and M. Mazars, {\\it Mol. Phys.\\/}, Paper I]. Sometimes, Lek...

Mazars, Martial

2007-01-01

4