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Thèses sur le sujet « Degenerine »

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Auteur : Grafiati

Publié le 10 mars 2023

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1

Limic, Mirna. « Monotone schemes for degenerate and non-degenerate parabolic problems ». Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/31763.

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This thesis analyses several monotone schemes for degenerate second order parabolic PDEs over two-dimensional domains which is in most cases equal (0, l )2 . For such problems the degeneracy means that in addition to the axis spanned by the standard basis vectors, there exists another pair of orthogonal cordinate axes such that the spatial difference operator is of the second order in one of the directions, and of the first order in the remaining directions. The direction of one axis along which the spatial difference operator is of the second order we call the direction of diffusion. The thesis considers only constant coefficient PDE's and therefore the degeneracy can be easily determined by solving the eigenvalue problem for diffusion tensor. We analyse the impact of the direction of diffusion on the convergence of a scheme. Previous work on a second order elliptic problem has shown that central differences taken in the direction of diffusion produce a convergent scheme, wherease disalignment between the two result in non-convergent schemes. One of our aims was to check the validity of this finding and possibly improve the construction of schemes. As a result we present a novel approach to building monotone schemes from the diffusion tensor by taking spatial step sizes of different length in order to align the second order central differences with the direction of diffusion. We give a step by step algorithm and supply all of the findings. Our findings are based on MATLAB m file, and C language implementations.
Science, Faculty of
Computer Science, Department of
Graduate

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2

Sinclair, Keith Ian. « Focussed microwave heating using degenerate and non-degenerate cavity modes ». Thesis, Heriot-Watt University, 2009. http://hdl.handle.net/10399/2288.

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Microwave ovens have long been recognised as a means of reducing heating times versus conventional convection ovens. The principle design feature is based on the procurement of uniform heating within any material placed in the interior of the microwave cavity oven. Materials within the oven are subjected to a degree of heating dependent on their electromagnetic properties. For many applications, it is desirable to maintain control over the distribution of heat deposition. This can be achieved through focussing of the electromagnetic field within the cavity. Two new mechanisms are identified where an increased level of control over the heating pattern and its location could be advantageous. The research described within this thesis aims to improve heating selectivity in microwave cavity ovens by the identification and enhanced control of modal patterns in degenerate and non-degenerate resonators. This is achieved through the analysis of two novel oven arrangements. The first of these addresses the requirement for highly selective heating in hyperthermia treatment. It is demonstrated that proper selection of a forced degenerate mode set can lead to an enhancement in field focussing within the centre of the cavity through constructive and destructive interference of the fields in each mode pattern. It is found that a highly selective peak of field can be produced within the centre of a large cylindrical waveguide cavity for the purpose of hyperthermia treatment. The peak is produced using a quasi degenerate mode set excited at approximately 1:3GHz. The second example presents an open oven design for the curing of epoxy and encapsulant materials within the micro-electronics packaging industry. It is intended that the oven be placed on the arm of a precision alignment machine such that the curing and placement stages of production be combined, suggesting an increase in production efficiency. Two excitation schemes are presented based on the coupling of quasi degenerate mode sets through a wide frequency range and the excitation of a single high order mode enabling uniform field distribution for heating of encapsulant material and increased selective heating through spatial alignment of modal field peaks, respectively. Experimental results demonstrate the viability of the open-ended microwave oven for curing. Both proposed excitation methods within the open oven design are investigated with results presented. Optimisation of the heating fields is achieved through inclusion of lowloss materials within the oven. Curing of an encapsulant material covering a commercial chip package is achieved and the overall design validated.

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3

柳井, 裕道, et HIROMICHI YANAI. « On Degenerate CM-types ». Elsevier, 1994. http://hdl.handle.net/2237/16361.

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4

Dugrain, Vincent. « Metrology with trapped atoms on a chip using non-degenerate and degenerate quantum gases ». Paris 6, 2012. http://www.theses.fr/2012PA066670.

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Le piégeage d’atomes sur puce ouvre de nouvelles possibilités pour la métrologie temps-fréquence et l’interférométrie atomique intégrée. L’expérience TACC (Trapped Atomic Clock on a Chip) a pour but d’étudier le potentiel des gaz quantiques, dégénérés ou non, pour la métrologie, et d’élaborer de nouveaux outils pour la manipulation des atomes. Elle vise notamment la réalisation d’un étalon secondaire de fréquence avec une stabilité de quelques 10-13 à une seconde. Cette thèse s’inscrit dans ce contexte. Nous y présentons les résultats de quelques expériences de métrologie réalisées avec des nuages thermiques ou des condensats de Bose-Einstein. Dans un premier temps nous démontrons une stabilité de 5. 8 x 10-13 à une seconde et caractérisons les bruits techniques limitant cette stabilité. Nous présentons ensuite une étude de la cohérence des condensats et en particulier l’effet des interactions. Les données sont comparées à un modèle numérique. Dans un deuxième temps nous présentons quelques outils développés pour la production et la manipulation d’atomes sur puce. Nous démontrons d’abord la réalisation d’un puissancemètre atomique pour la micro-onde et estimons les limites actuelles de ses performances. Nous démontrons ensuite que des champs micro-onde ayant des gradients élevés permettent la manipulation cohérente de l’état externe des atomes. Enfin nous présentons et caractérisons un nouveau dispositif pour la production de nuages d’atomes froids à haute cadence consistant en la modulation rapide de la pression de rubidium dans une cellule
Atom trapping on chip opens new perspectives for time and frequency metrology and integrated atom interferometry. The TACC experiment (Trapped Atomic Clock on a Chip) was built to study the potential of degenerate and non-degenerate quantum gases for metrology and to develop new tools for atom manipulation. One of the aims is the demonstration of a secondary frequency standard with a stability of a few 10-13 at one second. This is the context of this thesis. We report on several metrology experiments carried out with thermal clouds or Bose-Einstein condensates. Firstly, we demonstrate a stability of 5. 8 x 10-13 at one second and characterize the limiting technical noise. We then present a study of the coherence of Bose-Einstein condensates and, in particular, the effect of interactions. The data is compared with a numerical model. Secondly, we introduce several tools for producing and manipulating atoms on a chip. We show the realization of an atomic microwave powermeter and assess the current limits of its performance. We then demonstrate that high-gradient microwave fields allow one to coherently manipulate the atoms’ external motion. Finally, we present and characterize a new device for high-repetition rate atom loading involving fast modulation of the rubidium pressure

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5

Abed, Jamil, et Bert-Wolfgang Schulze. « Operators with corner-degenerate symbols ». Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2009/3029/.

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We establish elements of a new approch to ellipticity and parametrices within operator algebras on a manifold with higher singularities, only based on some general axiomatic requirements on parameter-dependent operators in suitable scales of spaces. The idea is to model an iterative process with new generations of parameter-dependent operator theories, together with new scales of spaces that satisfy analogous requirements as the original ones, now on a corresponding higher level. The “full” calculus is voluminous; so we content ourselves here with some typical aspects such as symbols in terms of order reducing families, classes of relevant examples, and operators near the conical exit to infinity.

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6

Grundling, Hendrik. « Algebraic structure of degenerate systems / ». Title page, table of contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phg888.pdf.

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7

BRUHN, KATHERINE LENEE. « DEGENERATE ART AND NAZI GERMANY ». Thesis, The University of Arizona, 2008. http://hdl.handle.net/10150/190433.

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8

Schmidt, Wolfram. « Turbulent thermonuclear combustion in degenerate stars ». [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970936532.

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9

Hofmanová, Martina. « Degenerate parabolic stochastic partial differential equations ». Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2013. http://tel.archives-ouvertes.fr/tel-00916580.

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In this thesis, we address several problems arising in the study of nondegenerate and degenerate parabolic SPDEs, stochastic hyperbolic conservation laws and SDEs with continues coefficients. In the first part, we are interested in degenerate parabolic SPDEs, adapt the notion of kinetic formulation and kinetic solution and establish existence, uniqueness as well as continuous dependence on initial data. As a preliminary result we obtain regularity of solutions in the nondegenerate case under the hypothesis that all the coefficients are sufficiently smooth and have bounded derivatives. In the second part, we consider hyperbolic conservation laws with stochastic forcing and study their approximations in the sense of Bhatnagar-Gross-Krook. In particular, we describe the conservation laws as a hydrodynamic limit of the stochastic BGK model as the microscopic scale vanishes. In the last part, we provide a new and fairly elementary proof of Skorkhod's classical theorem on existence of weak solutions to SDEs with continuous coefficients satisfying a suitable Lyapunov condition.

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10

Dekkers, Sophia Antonia Janna. « Degenerate parabolic equations on Riemannanian manifolds ». Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405755.

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11

Setiawan, Widagdo. « A new degenerate Fermi gas apparatus ». Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40912.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.
Includes bibliographical references (leaf 79).
In the summer of 2004, the BEC 2 lab of Wolfgang Ketterle's group at MIT started a new research direction of studying degenerate fermionic Lithium atoms in optical lattices. The major contributions to the new experimental setup are the Lithium laser system, a new imaging technique, and an advanced experiment control system. First, a tapered amplifier laser diode system is discussed. The laser is locked using an error signal generated using frequency modulation of saturated absorption spectroscopy of Lithium Vapor. The laser is then locked using a PID controller. Second, a new imaging system is developed. The imaging system is designed to eliminate noise generated by the mechanical vibrations of the machine. The system relies on taking multiple images with time scale shorter than typical vibration periods. Third, a new experiment control system is developed. The new control system replaced the outdated 8 years old control system by providing us with more channels and speed, combined with an automation feature. The new system is designed to accommodate more complex experiments in the future.
by Widagdo Setiawan.
S.B.

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12

Bernat, Lukáš. « Entropická degenerace demokracie a její modelování ». Master's thesis, Vysoká škola ekonomická v Praze, 2009. http://www.nusl.cz/ntk/nusl-19165.

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Democracy is always included in the discourse ?ver the theme of freedom and it is almost always considered an integral part of social order. In this context, it is a balance between freedom and power. Such discourses, however, view democracy as a political ideal and the real applications often run into democratic influences and social barriers of degenerative nature. These barriers leave nothing but the torso under the formal guise of democratic principles. This thesis unravels the influences and barriers that interfere with the application of the ideal of democracy. In this context, the technological development with which the dynamics of both social and political order changes, cannot be ignored. Based on the pieces of information about what kind of threat the degenerative effects of democracy represent, the thesis searches for such attributes, on the basis of which it is possible to construct a model of the entropic degeneration of democracy.

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13

DIDELOT, SOPHIE. « Etude d'une perturbation singuliere elliptique degeneree ». Reims, 1999. http://www.theses.fr/1999REIMS030.

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Cette these etudie un probleme de perturbation singuliere en dimension un pour un probleme aux limites concernant un operateur de type schrodinger. Ce dernier depend d'un petit parametre strictement positif, et le potentiel, egalement positif, degenere au bord. Cette particularite conduit a introduire des espaces a poids bien adaptes au probleme. On peut alors montrer que le probleme admet une solution bien definie dans ces espaces, pour des donnees convenables. On indique ensuite comment on peut construire des solutions approchees grace a des operateurs integraux bases sur les fonctions d'airy. On peut enfin en deduire des formules asymptotiques pour la vraie solution lorsque le petit parametre tend vers 0. Les termes d'erreur sont controles uniformement par rapport au petit parametre. La seconde partie est consacree a l'etude du probleme spectral. Apres avoir determine la nature du spectre, on utilise les techniques de la premiere partie pour obtenir des developpements asymptotiques des premieres valeurs propres et des fonctions propres associees. Dans le cas de double puits, ce developpement asymptotique des fonctions propres ne suffit pas pour analyser l'effet tunnel. On les approche alors par une methode bkw basee sur les points tournants. On en deduit le premier terme de l'asymptotique de l'effet tunnel.

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14

Schrohe, Elmar, et Bert-Wolfgang Schulze. « Edge-degenerate boundary value problems on cones ». Universität Potsdam, 1999. http://opus.kobv.de/ubp/volltexte/2008/2543/.

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We consider edge-degenerate families of pseudodifferential boundary value problems on a semi-infinite cylinder and study the behavior of their push-forwards as the cylinder is blown up to a cone near infinity. We show that the transformed symbols belong to a particularly convenient symbol class. This result has applications in the Fredholm theory of boundary value problems on manifolds with edges.

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15

Schwarzacher, Sebastian. « Regularity for degenerate elliptic and parabolic systems ». Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-162092.

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In this work local behavior for solutions to the inhomogeneous p-Laplace in divergence form and its parabolic version are studied. It is parabolic and non-linear generalization of the Calderon-Zygmund theory for the Laplace operator. I.e. the borderline case BMO is studied. The two main results are local BMO and Hoelder estimates for the inhomogenious p-Laplace and the parabolic p-Laplace system. An adaption of some estimates to fluid mechanics, namely on the p-Stokes equation are also proven. The p-Stokes system is a very important physical model for so-called non Newtonian fluids (e.g. blood). For this system BMO and Hoelder estimates are proven in the stationary 2-dimensional case.

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16

Giroux, Yves. « Degenerate enveloping algebras of low-rank groups ». Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74026.

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17

Charlton, A. « Degenerate four-wave mixing with pulsed lasers ». Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376890.

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18

Noorizadeh, Emad. « Highly degenerate diffusions for sampling molecular systems ». Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/7584.

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This work is concerned with sampling and computation of rare events in molecular systems. In particular, we present new methods for sampling the canonical ensemble corresponding to the Boltzmann-Gibbs probability measure. We combine an equation for controlling the kinetic energy of the system with a random noise to derive a highly degenerate diffusion (i.e. a diffusion equation where diffusion happens only along one or few degrees of freedom of the system). Next the concept of hypoellipticity is used to show that the corresponding Fokker-Planck equation of the highly degenerate diffusion is well-posed, hence we prove that the solution of the highly degenerate diffusion is ergodic with respect to the Boltzmann-Gibbs measure. We find that the new method is more efficient for computation of dynamical averages such as autocorrelation functions than the commonly used Langevin dynamics, especially in systems with many degrees of freedom. Finally we study the computation of free energy using an adaptive method which is based on the adaptive biasing force technique.

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19

Gotlibovych, Igor. « Degenerate Bose gases in a uniform potential ». Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708187.

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20

Gaunt, Alexander Lloyd. « Degenerate Bose gases : tuning interactions & ; geometry ». Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708720.

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21

Zhang, Zhou Ph D. Massachusetts Institute of Technology. « Degenerate Monge-Ampere equations over projective manifolds ». Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/34685.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2006.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 253-257).
In this thesis, we study degenerate Monge-Ampere equations over projective manifolds. The main degeneration is on the cohomology class which is Kähler in classic cases. Our main results concern the case when this class is semi-ample and big with certain generalization to more general cases. Two kinds of arguments are applied to study this problem. One is maximum principle type of argument. The other one makes use of pluripotential theory. So this article mainly consists of three parts. In the first two parts, we apply these two kinds of arguments separately and get some results. In the last part, we try to combine the results and arguments to achieve better understanding about interesting geometric objects. Some interesting problems are also mentioned in the last part for future consideration. The generalization of classic pluripotential theory in the second part may be of some interest by itself.
by Zhou Zhang.
Ph.D.

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22

Pears, J. R. « Degenerate critical points and the Conley index ». Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/15617.

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The thesis has two main themes: some homological results on the Conley index are put into a more natural homotopical context; and degenerate isolated critical points are studied from the point of view of the Conley index theory. A critical point of a smooth function is a rest point of the induced gradient flow so, if isolated, has a Conley index; this is the k-sphere, S^k, if the point is non-degenerate with Morse index k. The question as to which spaces can occur as the Conley index of a (degenerate) critical point is addressed. It is shown that the Lusternik Schnirelmann category of an invariant set (in general) is at least that of its Conley index less one. Consequently, the Conley index of a critical point can have Lusternik Schnirelmann category at most two. Conversely, the suspension of any finite CW-complex is shown to be the Conley index of a critical point of some function. A degenerate critical point may be broken up into a collection of non-degenerate points by perturbing the function in a neighbourhood of the point. The Conley index of the degenerate point is used to study this collection - homotopy invariants are introduced that give lower bounds on the number of critical values obtained in this manner. Despite its homotopical definition, much of the previous work using methods of algebraic topology with the Conley index concentrates on the homological properties of the index. This thesis, exploiting the definition of the Conley index as the homotopy type of a pointed space, studies the implications a flow on a space has on the homotopy of that space. It is shown that S-duality relates the forward and reverse flow Conley indices, generalising and clarifying a known Poincaré duality theorem on the homology of the indices.

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23

Burr, Justin R. « Degenerate Band Edge Resonators in Silicon Photonics ». The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449233730.

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24

Canto, Edesly J. « Picosecond degenerate four-wave mixing in semiconductors ». Thesis, University of North Texas, 1990. https://digital.library.unt.edu/ark:/67531/metadc798147/.

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This study reports on a variety of experimental and theoretical studies conducted in ZnSe, CdTe, and in semiconductor-doped glasses. The transient picosecond degenerate four-wave mixing (DFWM) experiments performed in these II-VI direct-gap semiconductors are part of our efforts to understand the picosecond dynamics of the free-carriers generated via two and three-photon absorption.

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25

Chen, Wenzhou. « QUANTUM DEGENERATE ATOMIC GASES IN OPTICAL CAVITIES ». Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195462.

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This dissertation contains a study of ultracold atoms in optical cavities. We particularly focus on two aspects of the coupled atom-cavity systems. In the first aspect, we implement the quantum nature of the light field to probe the quantum state of the atoms. This is interesting due to the nondestructive nature of the characterization of many-body atomic states. In the second aspect we study the cavity optomechanics that investigates the coupling of mechanical and optical degrees of freedom via radiation pressure. The optomechanical cavity provides an interesting nonlinear system to study the coupling between atoms and the intracavity field.In the context of cavity quantum electrodynamics we study the reflection of two counter-propagating modes of the light field in a high-Q ring cavity by ultracold atoms either in the Mott insulator state or in the superfluid state of an optical lattice. We find that the dynamics of the reflected light strongly depends on both the lattice spacing and the state of the matter-wave field. By using the Monte Carlo wave-function method to account for the cavity damping we also determine the two-time correlation function and the time-dependent physical spectrum of theretroreflected field. We find that the light field and the atoms become entangled if the latter are in a superfluid state. We also analyze quantitatively the entanglement between the atoms and the light.In cavity optomechanics the mechanical effect can either comes from a vibrating macroscopic oscillator or a collective density excitation of a Bose-Einstein condensate. First we use a Fabry-Perot-type cavity to study the opto-mechanically-induced bistable quantum phase transitions between superfluid and a Mott insulator states of an ultracold bosonic gases trapped inside the cavity. Secondly, we study the symmetricand antisymmetric collective density side modes of the BEC which results from the optomechanical effects of the light fields in a ring cavity.

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26

Voldman, Aleksandr. « Topological classification of non-degenerate quadratic system ». CSUSB ScholarWorks, 1996. https://scholarworks.lib.csusb.edu/etd-project/1192.

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27

Abdelrahman, Ahmed M. « Magnetic micro-confinement of quantum degenerate gases ». Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2011. https://ro.ecu.edu.au/theses/411.

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In this dissertation we explore the basic principles of the magnetic micro-confinement of the quantum degenerate gases where the approach of the so-called two-dimensional magnetic lattices has been theoretically and experimentally investigated. In this research a new generation of two-dimensional magnetic lattice has been proposed and considered as a developing phase for the previous approaches. Its advantage relies on introducing a simplified method to create single or multiple micro-traps of magnetic field local minima distributed, at a certain working distance, above the surface of a thin film of permanent magnetic material. The simplicity in creating the magnetic field local minima at the micro-scale manifests itself as a result of imprinting specific patterns through the thin film using suitable and available micro-fabrication techniques. In this approach, to create multiple micro-traps, patterned square holes of size αh X αh spaced by αs are periodically distributed across the x/y plane taking a two-dimensional grid configuration. These magnetic field local minima are recognized by their ability to trap and confine quantum single-particles and quantum degenerate gases at various levels of distribution in their phase spaces, such as ultracold atoms and virtual quantum particles. Based on the nature of the interaction between the external confining potential fields and the different types of quantum particles, this research is conducted through two separate but not different phases. We performed theoretical and/or experimental investigations, for both phases, at the vicinity of the magnetic micro-confinement and its suitability for trapping quantum particles. A special attention is paid to inspect the coherence in such systems defined in terms of providing an accessible coupling to the internal quantum states of the magnetically trapped particles. Such coherence is considered as one of the important ingredients for simulating condensed matter systems and processing quantum information.

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28

Bowen, Mark. « High order diffusion ». Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267628.

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29

Occhiuto, Enrico. « Materia degenere : fisica e applicazioni astrofisiche ». Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16166/.

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La degenerazione rappresenta uno stato della materia, in condizioni estreme di temperatura e densità, nel quale per descrivere il comportamento delle particelle bisogna tenere conto di effetti quantistici. Col seguente elaborato si vuole fornire una panoramica generale sullo stato degenere della materia e le sue principali applicazioni in astrofisica. L’obiettivo di questa tesi di laurea è quello di fornire un’analisi del diverso comportameto di partcelle bosoniche e fermioniche in stato di degenereazione, portando poi l’attenzione su come tali aspetti si riflettano in strutture stellari come le nane bianche e le stelle di neutroni. La tesi è articolata su due capitoli: nel primo viene fornita un introduzione sulla fisica della materia degenere, enunciando il principio di esclusione di Pauli e descrivendo le distribuzioni di Fermi-Dirac e Bose-Einstein. Nel secondo capitolo viene mostrato come cambi la descrizione della pressione in ambiente degenere. Infine, sulla base di questi risultati, vengono trattati alcuni esempi astrofisici, in particolare si pone particolare attenzione a come la degenerazione caratterizzi il raggio e la massa di stelle come le nane bianche e le stelle di neutroni.

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Albini, Silvio. « Materia degenere : fisica e applicazioni astrofisiche ». Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20012/.

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Il comportamento della materia risente in maniera rilevante delle particolari condizioni di temperatura e di pressione in cui si trova. Con il seguente elaborato si vuole inizialmente dare una panoramica di come un insieme di particelle si comporta in condizioni termodinamiche "standard", successivamente descrivere come la materia modifichi il proprio comportamento in condizioni di pressione estrema e quali risultano essere le applicazioni astrofisiche. Nella prima parte, dopo aver descritto un sistema di N particelle, si cercherà di mostrare il confine sottile oltre il quale gli effetti quantistici entrano in gioco in maniera predominante, approfondendo poi le due categorie di particelle utili alla descrizione degli interni stellari: Bosoni e Fermioni. Nella seconda parte si mostrano tutte le componenti che contribuiscono alla pressione totale negli interni stellari, riassumendoli in un grafico utile alla collocazione delle Stelle nelle loro diverse fasi evolutive. Dopo aver dato una panoramica dei diversi stadi caratterizzanti la vita di una stella in base alla propria massa iniziale, ci concentreremo su due casi specifici in cui la pressione di degenerazione gioca un ruolo fondamentale: le nane bianche e la stella di neutroni.

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Arico, Giovanni. « Materia degenere : Fisica e applicazioni astrofisiche ». Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7393/.

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Con la presente Tesi si vuole trattare lo Stato Degenere della materia. Nella prima parte si presenteranno le caratteristiche fisiche principali: limite di non degenerazione, differenze tra bosoni e fermioni, equazioni di stato e distribuzioni di velocità. Nella seconda parte si introdurranno i risvolti astrofisici più interessanti: pressione negli interni stellari, nane bianche, stelle di neutroni e Supernovae di tipo Ia.

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Hamburger, Christoph. « Regularity of differential forms minimizing degenerate elliptic functionals ». Bonn : [s.n.], 1989. http://catalog.hathitrust.org/api/volumes/oclc/20436844.html.

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Spani, Molella Luca. « Nonlinear spectroscopy of closed degenerate two-level systems ». [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=983879591.

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Tepoyan, L. « The mixed problem for a degenerate operator equation ». Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2009/3033/.

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We consider a mixed problem for a degenerate differentialoperator equation of higher order. We establish some embedding theorems in weighted Sobolev spaces and show existence and uniqueness of the generalized solution of this problem. We also give a description of the spectrum for the corresponding operator.

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Ikeda, Katsumoto. « Magnetothermoelectric properties of the degenerate semiconductor Hg1-xFexSe ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ53000.pdf.

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Berhane, Bereket H. « Quantum optical interactions in trapped degenerate atomic gases ». Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/29891.

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Bratfalean, Radu T. « Theory and applications of degenerate four-wave mixing ». Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301172.

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McCarron, Daniel John. « A quantum degenerate mixture of ⁸⁷Rb and ¹³³Cs ». Thesis, Durham University, 2011. http://etheses.dur.ac.uk/3242/.

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This thesis reports the formation of a dual-species Bose-Einstein condensate of ⁸⁷Rb and ¹³³Cs in the same trapping potential. Quantum degenerate mixtures exhibit rich physics inaccessible to single species experiments and provide an ideal starting point for the creation of ultracold dipolar molecules. These molecules offer a wealth of new research avenues including precision metrology, quantum simulation and computation. The experimental method exploits the efficient sympathetic cooling of ¹³³Cs via elastic collisions with ⁸⁷Rb, initially in a magnetic quadrupole trap and subsequently in a levitated optical trap. Evaporative cooling in the dipole trap must compete against a high interspecies three-body inelastic collision rate ~ 10⁻²⁵ - 10⁻²⁶ cm⁶/s. The two condensates each contain up to 2 x 10⁴ atoms and exhibit a striking phase separation, revealing the mixture to be immiscible due to strong repulsive interspecies interactions. Sacrificing all the ⁸⁷Rb during the cooling leads to the creation of single-species ¹³³Cs condensates of up to 6 x 10⁴ atoms. In addition this thesis reports the observation of an interspecies Feshbach resonance at 181.7(5)G and the creation of a pure sample of Cs₂ molecules via magneto-association on the 4(g)4 resonance at 19.8 G. These results represent important steps towards the creation of ultracold polar RbCs molecules.

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Hakulinen, Ville. « Passive advection and the degenerate elliptic operators Mn ». Helsinki : University of Helsinki, 2002. http://ethesis.helsinki.fi/julkaisut/mat/matem/vk/hakulinen/.

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Fukuhara, Takeshi. « Production of Quantum Degenerate Gases of Ytterbium Atoms ». 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124403.

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Kulp, Christopher W. « Control of integrable Hamiltonian systems and degenerate bifurcations ». W&M ScholarWorks, 2004. https://scholarworks.wm.edu/etd/1539623443.

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In this dissertation, we study the control of near-integrable systems. A near-integrable system is one whose phase space has a similar structure to an integrable system during short time periods and for some parameter regime. We begin by studying the control of integrable Hamiltonian systems. The controller targets an exact solution to the integrable system using dissipative and conservative terms. We find that a Takens-Bogdanov bifurcation occurs in the limit of no dissipative control. The presence of a Takens-Bogdanov bifurcation implies that the control is highly susceptible to noise. We illustrate our results using a two- and four-dimensional integrable systems generated by low order truncations of solutions to the nonlinear Schrodinger equation (NLS). We then extend our results to a near-integrable system related to the NLS; the Ginzburg-Landau equation. We attempt to control the Ginzburg-Landau equation to a plane wave solution of the NLS. We show that for a certain parameter regime; a Takens-Bogdanov bifurcation occurs in the limit of no dissipative control. Through this example, we show that solutions of integrable systems can be viable control targets for related near-integrable systems.

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Burnett, P. D. S. « Radiative properties of confined plasmas ». Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275600.

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Kimber, Andrew. « The Jahn-Teller effect : some numerical and analytic methods ». Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257927.

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Di, Marco Marco. « Superfici rigate con mappa di Gauss degenere ». Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20962/.

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Obiettivo di questa tesi è studiare la relazione tra le superfici rigate sviluppabili e la mappa di Gauss. Una superficie rigata è, in maniera euristica, una superficie ottenuta da una retta che si muove nello spazio. Alcune di queste superfici vengono dette sviluppabili: sono le superfici rigate che godono della proprietà di essere localmente isometriche ad un piano. Intuitivamente ciò vuol dire che possono essere localmente “srotolate” su un piano: ne sono un esempio i coni e i cilindri. Per mappa di Gauss in geometria differenziale classica si intende una mappa che (almeno localmente) a ogni punto della superficie assegna un versore normale alla superficie. Tuttavia per i nostri scopi sarà più utile considerare una generalizzazione di tale mappa: considereremo una mappa che a ogni punto di una superficie associa il suo piano tangente. Diremo poi che una mappa di Gauss è degenere per una superficie quando la dimensione dell'immagine della superficie ottenuta attraverso la mappa di Gauss è minore della dimensione della superficie. Vedremo sostanzialmente che una superficie rigata è sviluppabile se e solo se ha mappa di Gauss degenere e che questa condizione non vale solo in R^3 ma anche in P^3(C).

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Zoboli, Marco. « Controllabilità a zero per equazioni differenziali degeneri ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4585/.

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Pesce, Antonello. « Stochastic fundamental solutions for a class of degenerate SPDEs ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14559/.

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In this thesis, we look for a fundamental solution for a broad, possibly degenerate class of stochastic partial differential equations (SPDEs), whose deterministic part is a Kolmogorov equation with coefficients measurable in the time variable. We use a version of the It\^o-Wentzell formula to reduce the SPDE to a PDE, for which we extend the classic Levi's parametrix method to find a fundamental solution.

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Herrmann, Torsten. « H^infinity well-posedness for degenerate p-evolution operators ». Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2012. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-99818.

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Untersucht wird das Cauchy Problem für degenerierte $p$-Evolutionsgleichungen. Dabei kann für Gleichungen höherer Ordnung in $D_t$, die nur von der Zeit abhängen, gezeigt werden, dass das Problem $H^\\infinity$ korrekt ist. Dafür werden gewisse Bedingungen an die Koeffizienten und deren erste Ableitungen gestellt. $H^\\infinity$ korrekt bedeutet dabei, dass die Anfangsdaten $u_0\\in H^s$, $u_1$ in einem dazugehörigen Sobolevraum und die Lösung bezüglich $x$ in $H^{s-s_0}$ liegen. Eine Notwendigkeit für die Bedingungen kann allerdings nicht gezeigt werden. Auch ist offen, ob der Regularitätsverlust wirklich eintritt. Später wird der Beweis erweitert um das Ergebniss für Koeffizienten zu zeigen, die in gewisser Weise auch vom Ort abhängen können. Im zweiten Teil der Dissertation geht es um Korrektheit für degenerierte $p$-Evolutionsgleichungen mit zeitabhängigen Koeffizienten und zweiter Ordnung in $D_t$. Gefordert werden Bedingungen an die Koeffizienten und die ersten beiden Ableitungen bezüglich der Zeit. Damit wird gezeigt, dass diese in Skalen von Sobolevräumen korrekt gestellt sind. Abschließend wird die Schärfe der Bedingungen und das tatsächliche Auftreten des Regularitätsverlustes in der Lösung bewiesen.

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Voigt, Arne-Christian. « Heteronuclear Molecules from a Quantum Degenerate Fermi-Fermi Mixture ». Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-106171.

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Jaiani, George, et Bert-Wolfgang Schulze. « Some degenerate elliptic systems and applications to cusped plates ». Universität Potsdam, 2004. http://opus.kobv.de/ubp/volltexte/2008/2686/.

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The tension-compression vibration of an elastic cusped plate is studied under all the reasonable boundary conditions at the cusped edge, while at the noncusped edge displacements and at the upper and lower faces of the plate stresses are given.

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Abed, Jamil, et Bert-Wolfgang Schulze. « Edge-degenerate families of ΨDO’s on an infinite cylinder ». Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2009/3036/.

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We establish a parameter-dependent pseudo-differential calculus on an infinite cylinder, regarded as a manifold with conical exits to infinity. The parameters are involved in edge-degenerate form, and we formulate the operators in terms of operator-valued amplitude functions.

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