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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Automatic Billiards Table / Automatisk Biljard

Zhou, Fei, Cai, Hantao, Zhang, Ruoyu January 2014 (has links)
With the development of the society, people are more willing to focus on their leisure activities. A growing number of new equipment are created nowadays. For example, automatic mahjong machine in China. Inspired by the automatic mahjong machine, we propose to add some devices on the billiard table to achieve sorting balls automatically. It includes recognition system, ball-separating system, and sorting system. We use Autodesk Inventor 2012 to model the billiards table. Some complex calculations and nonlinear analysis are completed by Matlab. Through our method, we can achieve the purpose of sorting balls automatically. / Med utvecklingen av samhället, människor är mer villiga att fokusera på sina fritidsaktiviteter. Ett växande antal av ny utrustning skapas nuförtiden. Till exempel, automatisk mahjong maskin i Kina. Inspirerad av den automatiska mahjong maskin, föreslår vi att lägga till några enheter på biljardbordet för att uppnå sorterings bollar automatiskt. Den innehåller igenkänningssystem, boll-separerar systemet, och sorteringssystem. Vi använder Autodesk Inventor 2012 för att modellera tabellen biljard. Vissa komplexa beräkningar och olinjär analys är klara med Matlab. Genom vår metod kan vi uppnå syftet att sortera bollar automatiskt.
12

Persistent Currents and Quantum Critical Phenomena in Mesoscopic Physics

Zelyak, Oleksandr 01 January 2009 (has links)
In this thesis, we study persistent currents and quantum critical phenomena in the systems of mesoscopic physics. As an introduction in Chapter 1 we familiarize the reader with the area of mesoscopic physics. We explain how mesoscopic systems are different from quantum systems of single atoms and molecules and bulk systems with an Avogadro number of elements. We also describe some important mesoscopic phenomena. One of the mathematical tools that we extensively use in our studies is Random Matrix Theorty. This theory is not a part of standard physics courses and for educational purposes we provide the basics of Random Matrix Theory in Chapter 2. In Chapter 3 we study the persistent current of noninteracting electrons in quantum billiards. We consider simply connected chaotic Robnik-Berry quantum billiard and its annular analog. The electrons move in the presence of a point-like magnetic flux at the center of the billiard. For the simply connected billiard, we find a large diamagnetic contribution to the persistent current at small flux, which is independent of the flux and is proportional to the number of electrons (or equivalently the density since we keep the area fixed). The size of this diamagnetic contribution is much larger than the previously studied mesoscopic fluctuations in the persistent current in the simply connected billiard. This behavior of persistent current can ultimately be traced to the response of the angular-momentum l = 0 levels (neglected in semiclassical expansions) on the unit disk to a point-like flux at its center. We observe the same behavior for the annular billiard when the inner radius is much smaller than the outer one. We also find that the usual fluctuating persistent current and Anderson-like localization due to boundary scattering are seen when the annulus tends to a one-dimensional ring. We explore the conditions for the observability of this phenomenon. In Chapter 4 we study quantum critical phenomena in a system of two coupled quantum dots connected by a hopping bridge. Both the dots and connecting region are assumed to be in universal Random Matrix crossover regimes between Gaussian orthogonal and unitary ensembles (defined in Chapter 2). We exploit a diagrammatic approach appropriate for energy separations much larger than the level spacing, to obtain the ensemble-averaged one- and two-particle Greens functions. We find that two main components of the twoparticle Green’s function (diffuson and Cooperon) can be described by separate scaling functions. We then use this information to investigate a model interacting system in which one dot has an attractive s-wave reduced Bardeen-Cooper-Schrieffer interaction, while the other is noninteracting but subject to an orbital magnetic field. We find that the critical temperature TC of the mean-field transition into the superconducting state in the first dot is non-monotonic in the flux through the second dot in a certain regime of interdot coupling. Likewise, the fluctuation magnetization above the critical temperature is also non-monotonic in this regime, can be either diamagnetic or paramagnetic, and can be deduced from the Cooperon scaling function. We end this thesis with conclusion in Chapter 5.
13

Quantum Mechanical Computation Of Billiard Systems With Arbitrary Shapes

Erhan, Inci 01 October 2003 (has links) (PDF)
An expansion method for the stationary Schrodinger equation of a particle moving freely in an arbitrary axisymmeric three dimensional region defined by an analytic function is introduced. The region is transformed into the unit ball by means of coordinate substitution. As a result the Schrodinger equation is considerably changed. The wavefunction is expanded into a series of spherical harmonics, thus, reducing the transformed partial differential equation to an infinite system of coupled ordinary differential equations. A Fourier-Bessel expansion of the solution vector in terms of Bessel functions with real orders is employed, resulting in a generalized matrix eigenvalue problem. The method is applied to two particular examples. The first example is a prolate spheroidal billiard which is also treated by using an alternative method. The numerical results obtained by using both the methods are compared. The second exampleis a billiard family depending on a parameter. Numerical results concerning the second example include the statistical analysis of the eigenvalues.
14

Dynamique des systèmes physiques, formes normales et chaînes de Markov / Dynamics of physical systems , normal forms and Markov chains

Romaskevich, Olga 07 December 2016 (has links)
Cette thèse porte sur le comportement asymptotique des systèmes dynamiques et contient cinq chapitres indépendants.Nous considérons dans la première partie de la thèse trois systèmes dynamiques concrets. Les deux premiers chapitres présentent deux modèles de systèmes physiques : dans le premier, nous étudions la structure géométrique des langues d'Arnold de l'équation modélisant le contact de Josephson; dans le deuxième, nous nous intéressons au problème de Lagrange de recherche de la vitesse angulaire asymptotique d'un bras articulé sur une surface. Dans le troisième chapitre nous étudions la géométrie plane du billard elliptique avec des méthodes de la géométrie complexe.Les quatrième et cinquième chapitres sont dédiés aux méthodes générales d'étude asymptotique des systèmes dynamiques. Dans le quatrième chapitre nous prouvons la convergence des moyennes sphériques pour des actions du groupe libre sur un espace mesuré. Dans le cinquième chapitre nous fournissons une forme normale pour un produit croisé qui peut s'avérer utile dans l'étude des attracteurs étranges de systèmes dynamiques. / This thesis deals with the questions of asymptotic behavior of dynamical systems and consists of six independent chapters. In the first part of this thesis we consider three particular dynamical systems. The first two chapters deal with the models of two physical systems: in the first chapter, we study the geometric structure and limit behavior of Arnold tongues of the equation modeling a Josephson contact; in the second chapter, we are interested in the Lagrange problem of establishing the asymptotic angular velocity of the swiveling arm on the surface. The third chapter deals with planar geometry of an elliptic billiard.The forth and fifth chapters are devoted to general methods of studying the asymptotic behavior of dynamical systems. In the forth chapter we prove the convergence of markovian spherical averages for free group actions on a probablility space. In the fifth chapter we provide a normal form for skew-product diffeomorphisms that can be useful in the study of strange attractors of dynamical systems.
15

Natural Smooth Measures on the Leaves of the Unstable Manifold of Open Billiard Dynamical Systems

Richardson, Peter A. (Peter Adolph), 1955- 12 1900 (has links)
In this paper, we prove, for a certain class of open billiard dynamical systems, the existence of a family of smooth probability measures on the leaves of the dynamical system's unstable manifold. These measures describe the conditional asymptotic behavior of forward trajectories of the system. Furthermore, properties of these families are proven which are germane to the PYC programme for these systems. Strong sufficient conditions for the uniqueness of such families are given which depend upon geometric properties of the system's phase space. In particular, these results hold for a fairly nonrestrictive class of triangular configurations of scatterers.
16

Directed Chaos in Magnetic Billiard Systems / Gerichtetes Chaos in magnetischen Billiad-Systemen

Prusty, Manamohan 15 December 2006 (has links)
No description available.
17

Automates Cellulaires, Automates à Partitions et Tas de Sable

Durand-Lose, Jérôme 17 June 1996 (has links) (PDF)
Cette thèse s'intéresse dans un premier temps aux automates cellulaires réversibles, et dans un second temps aux tas de sable linéaires. Nous construisons diverses simulations reliant les automates cellulaires aux automates à partitions, en particulier celle des automates cellulaires réversibles par les automates à partitions réversibles, ce qui était une conjecture depuis 1990. Par des constructions successives, nous montrons que le ``Billiard ball model'' de Toffoli et Margolus est capable de simuler tous les automates à partitions réversibles de dimension 2. En rassemblant ces résultats, nous montrons qu'il existe des automates cellulaires réversibles capables de simuler tous les automates cellulaires réversibles de même dimension. Dans un espace linéaire, ``Tas de sable'' et ``Chip firing game'' sont équivalents. Nous portons notre attention sur le cas où les grains tombent un à un. Des motifs délimités par des signaux apparaissent au sein des configurations engendrées. Nous étudions la dynamique du système et démontrons un équivalent asymptotique. Nous étendons nos méthodes et nos résultats à d'autres types de configurations initiales. Dans chaque cas étudié, le temps parallèle est inférieur au temps séquentiel dans un rapport de l'ordre du nombre de piles mises en œuvre.
18

Animovaný 3D model / Animated 3D Model

Konečný, Kamil January 2016 (has links)
This  thesis  deals  with  production  of  three-dimensional  animated  model. Thesis is about model of billiard table and visualization of balls motion on its surface. Using simulation methods to solve the problem of balls motion is the goal of this work. This thesis contains summary of physical phenomena which describe the ball motion. There are also animation and simulation techniques which are used to create a model involved in this work. This thesis also deals with description of software, which can be used to create a three-dimensional model, animation and define user interaction. The second part of thesis describes how simulation program and visualization application was made. In the end, there are charts which describe ball behaviour involved in this work.
19

Flutuações universais da condutância de Spin-Hall em uma cavidade caótica de Dirac

VASCONCELOS, Thiago Conrado de 22 February 2016 (has links)
Submitted by Mario BC (mario@bc.ufrpe.br) on 2017-02-07T13:36:07Z No. of bitstreams: 1 Thiago Conrado de Vasconcelos.pdf: 4646767 bytes, checksum: 61c228fc4590858e8ee056ac3909187e (MD5) / Made available in DSpace on 2017-02-07T13:36:07Z (GMT). No. of bitstreams: 1 Thiago Conrado de Vasconcelos.pdf: 4646767 bytes, checksum: 61c228fc4590858e8ee056ac3909187e (MD5) Previous issue date: 2016-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Throughout the latest years, the interest on Spintronics has increased. The principal purposes of the eld are to detect, manipulate, create and polarize spin currents. Within this topic, it is possible to emphasize the Spin Hall E ect(SEH) and the Inverse Spin Hall E ect(ISEH). In this dissertation, we analytically investigate the universal fluctuation of the conductance of the spin in a chaotic quantum point with chiral symmetry at low temperatures. We used random matrices theory and the expansion of the diagrammatic method for that purpose. We showed that when the chirality is broken, the universal fluctuation of the conductance dispersion is in the order of rms hGf sHi 0:18e=4 and that when there is the preservation of the chiral symmetry, the universal fluctuation of the conductance dispersion occurs in the order of rms [GqsH] 0:283e=4 which coincides with the literature. We also worked on ISEH, through the analytical analysis with the semi-classic expansion of the conductance and showed that in the semi-classic limit the relation rms [GqsH] = p2 rms hGf sHi is valid. / Ao longo dos últimos anos tem aumentado o interesse pelo estudo da spintrônica. O objetivo principal deste campo é detectar, manipular, criar e polarizar correntes de spin. Dentro deste tópico, se destaca o Efeito Hall (SHE) de Spin e Efeito Hall de Spin Inverso (ISHE). Neste trabalho investigamos analiticamente a flutuação universal da condutância de spin num ponto quântico caótico com simetria quiral a baixas temperaturas. Para isso, utilizamos a teoria de matrizes aleatória e a expansão do método diagramático. Mostramos que, quando a simetria de quiralidade é quebrada, a flutuação universal da condutância tem uma dispersão na ordem de na ordem de rms[GfsH] p2 0:18 e/4 e que, quando a simetria de quiralidade é preservada, a flutuação universal da condutância ocorre na ordem de rms[GqsH] 0.283 e/4 , o que está de acordo com a literatura. Em nosso trabalho também investigamos o (ISHE), por meio de uma análise analítica utilizamos a expansão semi-clássica da condutância e mostramos que no limite semi-clássico vale a relação rms[GqIsH] = p2 rms[GfIsH].
20

Propriedades de tranporte, caos e dissipação num sistema dinâmico não linear

Abud, Celso Vieira [UNESP] 19 February 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:25:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-19Bitstream added on 2014-06-13T20:53:31Z : No. of bitstreams: 1 abud_cv_me_rcla.pdf: 2091525 bytes, checksum: f8a3b24150a2a718ad53ff294a3c6844 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Procuramos nesta dissertação, entender e desenvolver estudos relacionados com o movimento de trajetórias caóticas num sistema dinâmico não linear. Esses estudos, envolvem uma abordagem sobre a quantificação de recorrências de trajetórias a uma região e sobre o transporte no espaço de fases. Nós escolhemos como modelo o bilhar anular em duas configurações: primeiramente com as fronteiras estáticas e posteriormente, uma dependência temporal (pulsante) e introduzida. Inicialmente reproduzimos os resultados sobre aprisionamentos para caso do bilhar estático, existentes na literatura, a fim de ganharmos experiência para estudar o sistema pulsante. Nesse caso, a topologia dos dois planos de fases possíveis constituídos de variáveis canônicas, apesar de bastante complexas, apresentaram resultados interessantes. Os principais resultados obtidos foram: a observação de regiões de aprisionamentos nos dois planos de fases conectadas entre si; a aceleração de Fermi caracterizada por vários regimes anômalos; ( uma explicação para a diferença desses regimes e dada por aprisionamentos no plano do bilhar) e a evolução do espaço de fases, dito geométrico, que tende a se recuperar conforme a velocidade relativa partícula-fronteira aumenta. Estudamos ainda os efeitos de dissipação no sistema pulsante através de colisões inelásticas. Os resultados indicam que qualquer dissipação desse tipo, independente da magnitude, é suficiente para saturar o crescimento de energia. Porém, em situações especiais essa mesma dissipação pode ser usada para que na média o sistema ganhe energia. / We reach in this dissertation, understand and develop studies related to the motion of the chaotic trajectories in a non-linear dynamical system. These studies require an approach on the quanti cation of the recurrences of trajectories to a region and on the transport in the phase space. We choose as a model the annular billiard with two con gurations: rstly with the static boundaries and next, a time-dependent (pulsating)is introduced. Initially we reproduced some results about stickiness in the static case in order to gain experience to study the pulsating system. In such case the topology of the two possible phase space of canonical variables, showed interesting results. The main results were: the observation of sticky regions in both connected phase spaces; the Fermi acceleration characterized by di erent anomalous regimes ( an explanation to this diferent regimes is given by the stickiness on the billiard plane) and the evolution of the phase space, called geometric, which tends to be recovered as the relative velocity particle-boundary increases. We also studied the e ects of dissipation in the pulsating system through inelastic collisions. The results show that this kind of dissipation, regardless of its magnitude, is enough to saturate the energy growth. However, in special situations the mean average of the system can increase with the introduction of inelastic collisions.

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