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Rozprawy doktorskie na temat „Dynamical Correlation”

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Data publikacji: 7 września 2023

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1

Kobayashi, Miki U. "Determination of dynamical correlation functions in chaotic systems". 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136009.

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2

Guzzo, Matteo. "Dynamical correlation in solids : a perspective in photoelectron spectroscopy". Phd thesis, Ecole Polytechnique X, 2012. http://pastel.archives-ouvertes.fr/pastel-00784815.

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My thesis fits into the domain of theoretical spectroscopy. This term describes a set of theoretical approaches that go hand-in-hand with several experimental techniques such as optical absorption and reflectivity, inelastic X-ray scattering (IXS), electron energy-loss spectroscopy (EELS) and photoelectron (or photoemission) spectroscopy. This set of ab-initio theories is used to simulate, study, predict and understand what is and will be seen in experiment. These spectroscopies are all connected to the dielectric function ε(ω ) of an electronic system which is, in fact, a fundamental quantity in many modern electronic structure theories. In particular I focused my research on photoemission spectroscopy, where the dielectric function enters as the screening of the hole due to the system. During my thesis I have worked on the development of new theoretical approaches, the aim of my project being to go beyond state-of-the-art methods used in electronic structure calculations. These methods stem mainly from two larger theoretical frameworks: Time-Dependent Density-functional Theory (TDDFT) and Green's function theory -- also known as Many-Body Perturbation Theory (MBPT). I carried on the theoretical development in parallel with numerical simulations on real materials and with experimental measurements, performed to verify the reliability of theory.
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3

Tupikina, Liubov. "Temporal and spatial aspects of correlation networks and dynamical network models". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17746.

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In der vorliegenden Arbeit untersuchte ich die komplexen Strukturen von Netzwerken, deren zeitliche Entwicklung, die Interpretationen von verschieden Netzwerk-Massen und die Klassen der Prozesse darauf. Als Erstes leitete ich Masse für die Charakterisierung der zeitlichen Entwicklung der Netzwerke her, um räumlich Veränderungsmuster zu erkennen. Als Nächstes führe ich eine neue Methode zur Konstruktion komplexer Netzwerke von Flussfeldern ein, bei welcher man das Set-up auch rein unter Berufung Berufung auf das Geschwindigkeitsfeld ändern kann. Diese Verfahren wurden für die Korrelationen skalarer Grössen, z. B. Temperatur, entwickelt, welche eine Advektions-Diffusions-Dynamik in der Gegenwart von Zwingen und Dissipation. Die Flussnetzwerk-Methode zur Zeitreihenanalyse konstruiert die Korrelationsmatrizen und komplexen Netzwerke. Dies ermöglicht die Charakterisierung von Transport in Flüssigkeiten, die Identifikation verschiedene Misch-Regimes in dem Fluss und die Anwendung auf die Advektions-DiffusionsDynamik, Klimadaten und anderen Systemen, in denen Teilchentransport eine entscheidende Rolle spielen. Als Letztes, entwickelte ich ein neuartiges Heterogener Opinion Status Modell (HOpS) und Analysetechnik basiert auf Random Walks und Netzwerktopologie Theorien, um dynamischen Prozesse in Netzwerken zu studieren, wie die Verbreitung von Meinungen in sozialen Netzwerken oder Krankheiten in der Gesellschaft. Ein neues Modell heterogener Verbreitung auf einem Netzwerk wird als Beispielssystem für HOpS verwendent, um die vergleichsweise Einfachheit zu nutzen. Die Analyse eines diskreten Phasenraums des HOPS-Modells hat überraschende Eigenschaften, welches sensibel auf die Netzwerktopologie reagieren. Sie können verallgemeinert werden, um verschiedene Klassen von komplexen Netzwerken zu quantifizieren, Transportphänomene zu charakterisieren und verschiedene Zeitreihen zu analysieren.
In the thesis I studied the complex architectures of networks, the network evolution in time, the interpretation of the networks measures and a particular class of processes taking place on complex networks. Firstly, I derived the measures to characterize temporal networks evolution in order to detect spatial variability patterns in evolving systems. Secondly, I introduced a novel flow-network method to construct networks from flows, that also allows to modify the set-up from purely relying on the velocity field. The flow-network method is developed for correlations of a scalar quantity (temperature, for example), which satisfies advection-diffusion dynamics in the presence of forcing and dissipation. This allows to characterize transport in the fluids, to identify various mixing regimes in the flow and to apply this method to advection-diffusion dynamics, data from climate and other systems, where particles transport plays a crucial role. Thirdly, I developed a novel Heterogeneous Opinion-Status model (HOpS) and analytical technique to study dynamical processes on networks. All in all, methods, derived in the thesis, allow to quantify evolution of various classes of complex systems, to get insight into physical meaning of correlation networks and analytically to analyze processes, taking place on networks.
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4

Vanzini, Marco. "Auxiliary systems for observables : dynamical local connector approximation for electron addition and removal spectra". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX012/document.

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Cette thèse propose une méthode théorique innovante pour l'étude des spectres d'excitation à un électron, mesurée par spectroscopie de photoémission directe et inverse.La plupart des calculs actuels au niveau de l’état de l’art reposent sur des fonctions de Green à plusieurs corps et des self-énergies complexes et non locales, évaluées spécifiquement pour chaque matériau. Même lorsque les spectres calculés sont en très bon accord avec les expériences, le coût de calcul est très important. La raison est que la méthode elle-même n'est pas efficace, car elle fournit beaucoup d'informations superflues qui ne sont pas nécessaires pour l'interprétation des données expérimentales.Dans cette thèse, nous proposons deux raccourcis par rapport à la méthode standard. Le premier est l'introduction d'un système auxiliaire qui cible, en principe, le spectre d'excitation du système réel. L'exemple type est la théorie de la fonctionnelle de la densité, pour lequel le système auxiliaire est le système de Kohn-Sham : elle reproduit exactement la densité du système réel par l'intermédiaire d'un potentiel réel et statique, le potentiel de Kohn-Sham. La théorie de la fonctionnelle de la densité est, cependant, une théorie de l'état fondamental, qui ne fournit que rarement des propriétés d'état excités : un exemple est le fameux problème de la sous-estimation de la bande interdite. Le potentiel que nous proposons (le potentiel spectral), local et dépendant de la fréquence, mais réelle, peut être considéré comme une généralisation dynamique du potentiel de Kohn-Sham qui donne en principe le spectre exact.Le deuxième raccourci est l'idée de calculer ce potentiel une fois pour toute dans un système modèle, le gaz d'électrons homogène, et de le tabuler. Pour étudier des matériaux réels, nous concevons un connecteur qui prescrit l'utilisation des résultats du gaz pour calculer les spectres électroniques.La première partie de la thèse traite de l'idée de systèmes auxiliaires, montrant le cadre général dans lequel ils peuvent être introduits et les équations qu'ils doivent satisfaire. Nous utilisons des modèles de Hubbard solubles exactement pour mieux comprendre le rôle du potentiel spectral ; en particulier, il est démontré que le potentiel peut être défini uniquement chaque fois que le spectre est non nul, et donne toujours les spectres attendus, même lorsque la partie imaginaire ou les contributions non locales de la self-énergie jouent un rôle de premier plan.Dans la deuxième partie de la thèse, nous nous concentrons sur les calculs pour les systèmes réels. Nous évaluons d'abord le potentiel spectral dans le gaz d'électrons homogène, puis l'importons dans le système auxiliaire pour évaluer le spectre d'excitation. Toute l’interdependence non triviale entre l'interaction électronique et l'inhomogénéité du système réel entre dans la forme du connecteur. Trouver une expression pour cela est le véritable défi de la procédure. Nous proposons une approximation raisonnable basée sur les propriétés locales du système, que nous appelons approximation du connecteur dynamique local.Nous mettons en œuvre cette procédure pour quatre prototypes de matériaux différents : le sodium, un métal presque homogène ; l'aluminium, encore un métal mais moins homogène ; le silicium, un semi-conducteur ; l'argon, un isolant inhomogène. Les spectres que nous obtenons avec cette approche concordent de manière impressionnante avec ceux qui sont évalués via la self-énergie, très coûteuse en temps de calcul, démontrant ainsi le potentiel de cette théorie
This thesis proposes an innovative theoretical method for studying one-electron excitation spectra, as measured in photoemission and inverse photoemission spectroscopy.The current state-of-the-art realistic calculations rely usually on many-body Green’s functions and complex, non-local self energies, evaluated specifically for each material. Even when the calculated spectra are in very good agreement with experiments, the computational cost is very large. The reason is that the method itself is not efficient, as it yields much superfluous information that is not needed for the interpretation of experimental data.In this thesis we propose two shortcuts to the standard method. The first one is the introduction of an auxiliary system that exactly targets, in principle, the excitation spectrum of the real system. The prototypical example is density functional theory, in which the auxiliary system is the Kohn-Sham system: it exactly reproduces the density of the real system via a real and static potential, the Kohn-Sham potential. Density functional theory is, however, a ground state theory, which hardly yields excited state properties: an example is the famous band-gap problem. The potential we propose (the spectral potential), local and frequency-dependent, yet real, can be viewed as a dynamical generalisation of the Kohn-Sham potential which yields in principle the exact spectrum.The second shortcut is the idea of calculating this potential just once and forever in a model system, the homogeneous electron gas, and tabulating it. To study real materials, we design a connector which prescribes the use of the gas results for calculating electronic spectra.The first part of the thesis deals with the idea of auxiliary systems, showing the general framework in which they can be introduced and the equations they have to fulfill. We then use exactly-solvable Hubbard models to gain insight into the role of the spectral potential; in particular, it is shown that a meaningful potential can be defined wherever the spectrum is non-zero, and that it always yields the expected spectra, even when the imaginary or the non-local parts of the self energy play a prominent role.In the second part of the thesis, we focus on calculations for real systems. We first evaluate the spectral potential in the homogeneous electron gas, and then import it in the auxiliary system to evaluate the excitation spectrum. All the non-trivial interplay between electron interaction and inhomogeneity of the real system enters the form of the connector. Finding an expression for it is the real challenge of the procedure. We propose a reasonable approximation for it, based on local properties of the system, which we call dynamical local connector approximation.We implement this procedure for four different prototypical materials: sodium, an almost homogeneous metal; aluminum, still a metal but less homogeneous; silicon, a semiconductor; argon, an inhomogeneous insulator. The spectra we obtain with our approach agree to an impressive extent with the ones evaluated via the computationally expensive self energy, demonstrating the potential of this theory
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5

Hagy, Matthew Canby. "Dynamical simulation of structured colloidal particles". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50328.

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In this thesis, computer simulations are used to study the properties of new colloidal systems with structured interactions. These are pair interactions that include both attraction and repulsion. Structured colloids differ from conventional colloids in which the interactions between particles are either strictly attractive or strictly repulsive. It is anticipated that these novel interactions will give rise to new microscopic structure and dynamics and therefore new material properties. Three classes of structured interactions are considered: radially structured interactions with an energetic barrier to pair association, Janus surface patterns with two hemispheres of different surface charge, and striped surface patterns. New models are developed to capture the structured interactions of these novel colloid systems. Dynamical computer simulations of these models are performed to quantify the effects of structured interactions on colloid properties. The results show that structured interactions can lead to unexpected particle ordering and novel dynamics. For Janus and striped particles, the particle order can be captured with simpler isotropic coarse-grained models. This relates the static properties of these new colloids to conventional isotropically attractive colloids (e.g. depletion attracting colloids). In contrast, Janus and striped particles are found to have substantially slower dynamics than isotropically attractive colloids. This is explained by the observation of longer-duration reversible bonds between pairs of structured particles. Dynamical mapping methods are explored to relates the dynamics of these structured colloids to isotropically attractive colloids. These methods could also facilitate future nonequilibrium simulation of structured colloids with computationally efficient coarse-grained models.
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6

Thunström, Patrik. "Correlated Electronic Structure of Materials : Development and Application of Dynamical Mean Field Theory". Doctoral thesis, Uppsala universitet, Materialteori, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-173300.

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This thesis is dedicated to the development, implementation and application of a combination of Density Functional Theory and Dynamical Mean Field Theory. The resulting program is shown through several examples to be a powerful and flexible tool for calculating the electronic structure of strongly correlated materials. The main part of this work is focused on the development and implementation of three methods for solving the effective impurity model arising in the Dynamical Mean Field Theory: Hubbard-I approximation (HIA), Exact Diagonalization (ED), and Spin-Polarized T-matrix Fluctuation-exchange (SPTF). The Hubbard-I approximation is limited to systems where the hybridization between the 4f-orbitals and the rest of the material can be completely neglected, and can therefore not capture any Kondo physics. It has been used to study the atomic-like multiplet spectrum of the strongly localized 4f-electrons in the Lanthanide compounds YbInCu4, YbB12, Yb2Pd2Sn, YbPd2Sn, SmB6, SmSn3, and SmCo5. The calculated spectral properties are shown to be in excellent agreement with experimental direct and inverse photoemission data, clearly affirming the applicability of the Hubbard-I approximation for this class of systems if we are not focusing on Kondo physics. Full self-consistence in both self-energy and electron density is shown to be of key importance in the extraction of the magnetic properties of the hard permanent magnet SmCo5. The Exact Diagonalization solver is implemented as an extension of the Hubbard-I approximation. It takes into account a significant part of the hybridization between the correlated atom and the host through the use of a few effective bath orbitals. This approach has been applied to the long-standing problem of the electronic structure of NiO, CoO, FeO, and MnO. The resulting spectral densities are favorably compared to photoemission spectroscopy. Apart from predicting the correct spectral properties, the Exact Diagonalization solver also provides full access to the many-body density operator. This feature is used to make an in-depth investigation of the correlations in the electronic structure, and two measures of the quantum entanglement of the many-body ground-states are presented. It is shown that CoO possesses the most intricate entanglement properties, due to a competition between crystal field effects and Coulomb interaction, and such a mechanism likely carries over to several classes of correlated electron systems. The Exact Diagonalization solver has also been applied to the prototypical dilute magnetic semiconductor Mn doped GaAs, a material of great importance in the study of future spintronics applications. The problem of Fe impurities in Cs has been used to study the dependence of the spectral properties on the local environment. Finally, the Spin-polarized T-matrix Fluctuation-exchange solver has been implemented and applied to more delocalized electron systems where the effective impurity problem can be solved as a perturbation with respect to the strength of the local Coulomb interaction. This approach has been used to study the magnetic and spectral properties of the late transition metals, Fe, Co and Ni, and NiS.
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Avila, Karina E. "Dynamical Heterogeneity in Granular Fluids and Structural Glasses". Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1389072160.

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8

Lacevic, Naida. "Dynamical heterogeneity in simulated glass-forming liquids studied via a four-point spatiotemporal density correlation function". Available to US Hopkins community, 2003. http://wwwlib.umi.com/dissertations/dlnow/3080704.

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Lott, Geoffrey Adam 1980. "Probing local conformation and dynamics of molecular complexes using phase-selective fluorescence correlation and coherence spectroscopy". Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/10914.

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xv, 177 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
When two or more fluorescent chromophores are closely spaced in a macromolecular complex, dipolar coupling leads to delocalization of the excited states, forming excitons. The relative transition frequencies and magnitudes are sensitive to conformation, which can then be studied with optical spectroscopy. Non-invasive fluorescence spectroscopy techniques are useful tools for the study of dilute concentrations of such naturally fluorescent or fluorescently labeled biological systems. This dissertation presents two phase-selective fluorescence spectroscopy techniques for the study of dynamical processes in bio-molecular systems across a wide range of timescales. Polarization-modulated Fourier imaging correlation spectroscopy (PM-FICS) is a novel phase-selective fluorescence spectroscopy for simultaneous study of translational and conformational dynamics. We utilize modulated polarization and intensity gratings with phase-sensitive signal collection to monitor the collective fluctuations of an ensemble of fluorescent molecules. The translational and conformational dynamics can be separated and analyzed separately to generate 2D spectral densities and joint probability distributions. We present results of PM-FICS experiments on DsRed, a fluorescent protein complex. Detailed information on thermally driven dipole-coupled optical switching pathways is found, for which we propose a conformation transition mechanism. 2D phase-modulation electronic coherence spectroscopy is a third-order nonlinear spectroscopy that uses collinear pulse geometry and acousto-optic phase modulation to isolate rephasing and nonrephasing contributions to the collected fluorescence signal. We generate 2D spectra, from which we are able to determine relative dipole orientations, and therefore structural conformation, in addition to detailed coupling information. We present results of experiments on magnesium tetraphenylporphyrin dimers in lipid vesicle bilayers. The 2D spectra show clearly resolved diagonal and off-diagonal features, evidence of exciton behavior. The amplitudes of the distinct spectral features change on a femtosecond timescale, revealing information on time-dependent energy transfer dynamics. This dissertation includes co-authored and previously published material.
Committee in charge: Hailin Wang, Chairperson, Physics; Andrew Marcus, Advisor, Chemistry; Stephen Gregory, Member, Physics; Michael Raymer, Member, Physics; Marina Guenza, Outside Member, Chemistry
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Tupikina, Liubov [Verfasser], Jürgen [Gutachter] Kurths, Lutz [Gutachter] Schimansky-Geier i Sergei [Gutachter] Nechaev. "Temporal and spatial aspects of correlation networks and dynamical network models : analytical approaches and physical applications / Liubov Tupikina ; Gutachter: Jürgen Kurths, Lutz Schimansky-Geier, Sergei Nechaev". Berlin : Mathematisch-Naturwissenschaftliche Fakultät, 2017. http://d-nb.info/1130698483/34.

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dePillis-Lindheim, Lydia. "Disease Correlation Model: Application to Cataract Incidence in the Presence of Diabetes". Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/scripps_theses/294.

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Diabetes is a major risk factor for the development of cataract [3,14,20,22]. In this thesis, we create a model that allows us to understand the incidence of one disease in the context of another; in particular, cataract in the presence of diabetes. The World Health Organization's Vision 2020 blindness-prevention initiative administers surgeries to remove cataracts, the leading cause of blindness worldwide [24]. One of the geographic areas most impacted by cataract-related blindness is Sub-Saharan Africa. In order to plan the number of surgeries to administer, the World Health Organization uses data on cataract prevalence. However, an estimation of the incidence of cataract is more useful than prevalence data for the purpose of resource planning. In 2012, Dray and Williams developed a method for estimating incidence based on prevalence data [5]. Incidence estimates can be further refined by considering associated risk factors such as diabetes. We therefore extend the Dray and Williams model to include diabetes prevalence when calculating cataract incidence estimates. We explore two possible approaches to our model construction, one a detailed extension, and the other, a simplification of that extension. We provide a discussion comparing the two approaches.
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Jeffrey, Chris C. "Applications of Single Reference Methods to Multi-Reference Problems". Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc801919/.

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Density functional theory is an efficient and useful method of solving single-reference computational chemistry problems, however it struggles with multi-reference systems. Modifications have been developed in order to improve the capabilities of density functional theory. In this work, density functional theory has been successfully applied to solve multi-reference systems with large amounts of non-dynamical correlation by use of modifications. It has also been successfully applied for geometry optimizations for lanthanide trifluorides.
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Forti, Rodrigo Menezes 1990. "Determination of the dynamical properties in turbid media using diffuse correlation spectroscopy = applications to biological tissue = Determinação das propriedades dinâmicas em meios turvos usando espectroscopia de correlação de difusão: aplicações ao tecido biológico". [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276955.

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Orientador: Rickson Coelho Mesquita
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
Made available in DSpace on 2018-08-27T04:25:10Z (GMT). No. of bitstreams: 1 Forti_RodrigoMenezes_M.pdf: 12387880 bytes, checksum: 7008f6dbed4a5d63effefff5a6582b33 (MD5) Previous issue date: 2015
Resumo: Técnicas de espectroscopia baseadas em óptica de difusão são essenciais para a obtenção das propriedades ópticas e dinâmicas em meios turvos, caracterizados pela predominância dos efeitos de espalhamento sobre a absorção. Nestas condições, a luz se propaga esfericamente no meio, num regime aproximadamente difusivo. A luz espalhada pode então ser detectada no mesmo plano de incidência, e sua detecção fornece informação das propriedades ópticas e dinâmicas das moléculas que compõem o meio. Em particular, a técnica encontra uma vasta aplicação no estudo das propriedades do tecido biológico, uma vez que este se comporta como um meio turvo na região do infravermelho próximo. Por se tratar de uma técnica experimental relativamente recente, pouco é conhecido em relação à propagação da luz em meios com diferentes geometrias, principalmente em relação às propriedades dinâmicas do meio. Este projeto propôs um estudo teórico-experimental detalhado da propagação da luz em meios turvos semi-infinitos e de duas camadas, com foco na obtenção das propriedades dinâmicas do meio, através de uma técnica óptica de difusão conhecida como espectroscopia de correlação de difusão (DCS). Mais especificamente, esse projeto testou as geometrias de um meio semi-infinito e de duas camadas, com o uso de simulações de Monte Carlo e experimentos em ambientes controlados. Foi mostrado que o uso da geometria de duas camadas, ao invés da de um meio semi-infinito, como é usualmente feito na literatura, traz melhoras significativas para a recuperação das propriedades de fluxo do meio. As geometrias usadas neste trabalho representam aproximações mais precisas das estruturas muscular e cerebral, por exemplo, e retratam diferentes situações encontradas em Biologia e Medicina. Por fim, o sistema também foi testado em voluntários sadios. Os resultados obtidos neste projeto tem aplicação direta nas áreas citadas, e podem contribuir significativamente para o desenvolvimento de técnicas físicas para o monitoramento cerebral e muscular na clínica médica
Abstract: Spectroscopic techniques based on diffuse optics are essential for determination of the optical and dynamical properties of turbid media, in which scattering predominates over absorption. Under these conditions, light propagates spherically in the medium, in an approximate diffusive regimen. Scattered light can thus be detected at the same plane of incidence, and its detection can provide information both on the optical and dynamical properties of the medium. Diffuse optical techniques are particularly useful to study the properties of biological tissue, since it behaves like a turbid medium in the near infrared region. Because diffuse optics is a relatively novel experimental technique, not much is known regarding the propagation of light in media with different geometries, particularly with relation to the dynamical properties of the medium. This project proposes a combined theoretical and experimental study of light propagation in semi-infinite and two-layered turbid media, focusing on the dynamical properties of the medium with a diffuse optical technique called diffuse correlation spectroscopy (DCS). More specifically, this project employed the semi-infinite and the two-layer geometries, testing them using Monte Carlo simulations and controlled enviroments. It was shown that by using a two-layer geometry, instead of the semi-infinite geometry, as routinely done in the literature, it is possible to significantly improve the accuracy of the recovered dynamical properties. The geometries tested in this work represent more accurate approximations for muscle and brain structures, for example, and therefore could depict different situations encountered in problems in the fields of Biology and Medicine. Last, the system was also tested in healthy subjects. The results obtained in this project have direct application in the above-cited fields, and may significantly contribute to the development of experimental techniques for diagnosis and/or monitoring of the brain and muscle in the clinic
Mestrado
Física
Mestre em Física
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Fontes, Nuno Ricardo Moura. "Sistemas dinâmicos, análise numérica de séries temporais e aplicações às finanças". Master's thesis, Instituto Superior de Economia e Gestão, 2013. http://hdl.handle.net/10400.5/6454.

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Mestrado em Matemática Financeira
Taken's theorem (1981) shows how the series of measurements from a given system can be used to reconstruct the original system's underlying dynamic process. In this work we start from this point and build a bridge between theoretical results and its practical application. Several algorithms are presented and then rebuilt in an effort to reach a middle ground between computer resources optimization and output accuracy. Among these algorithms, the biggest emphasis is put on the correlation dimension algorithm by Grassberger and Procaccia which allows for the deduction of the system's embedding dimension. The results derived are then used to build a forecast approach inspired by the analogues method. The purpose of this work is to show there is potential for dynamical systems' modelling tools to be used in financial markets, especially for intra-day purposes where decision and computational times need to be very small.
O teorema de Takens (1981) mostra como uma série de medições obtidas de um dado sistema podem ser usadas para reconstruir o sistema dinâmico original. Neste trabalho, parte-se deste teorema e constrói-se a ponte entre conceitos teóricos e a sua aplicação numérica. Vários algoritmos são apresentados e depois reconstruídos com o objetivo de se atingir um compromisso entre otimização de recursos computacionais e rigor nos resultados. Entre esses algoritmos, a maior ênfase é colocada no do cálculo do integral de correlação de Grassberger-Procaccia que permite a dedução da dimensão de imersão de um dado sistema. Os resultados obtidos são usados na construção de um modelo de previsão inspirado pela abordagem dos pontos análogos, ou método dos análogos. O objetivo deste trabalho é mostrar que existe potencial na aplicação de ferramentas de modelação de sistemas dinâmicos caóticos no mercado financeiro, em especial em transações intra-diárias onde tempos de decisão e computação têm de ser muito reduzidos.
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James, Andrew J. A. "Dynamical Correlations of Low Dimensional Quantum Magnets". Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490085.

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The dynamical structure factor (DSF) is an important quantity in the characterization and understanding of quantum magnets, both experimentally and theoretically. In this thesis the DSF is calculated for three different spin-1/2 systems with reduced spatial dimensions. These are: the bond alternating Heisenberg chain; the anisotropic Heisenberg, or XXZ, chain; and n a anisotropic triangular antiferromagnet with Dzyaloshinskii-Moriya interaction. All three cases are motivated by inelastic neutron scattering experiments on realistic manifestations of the models.
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DeVane, Russell H. "Molecular dynamics and time correlation function theories". [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001309.

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17

Pereira, Rodrigo Gonçalves. "Dynamical correlations of S=1/2 quantum spin chains". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/939.

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Spin-1/2 chains demonstrate some of the striking effects of interactions and quantum fluctuations in one-dimensional systems. The XXZ model has been used to study the unusual properties of anisotropic spin chains in an external magnetic field. The zero temperature phase diagram for this model exhibits a critical or quasi-long-range-ordered phase which is a realization of a Luttinger liquid. While many static properties of spin-1/2 chains have been explained by combinations of analytical techniques such as bosonization and Bethe ansatz, the standard approach fails in the calculation of some time-dependent correlation functions. I present a study of the longitudinal dynamical structure factor for the XXZ model in the critical regime. I show that an approximation for the line shape of the dynamical structure factor in the limit of small momentum transfer can be obtained by going beyond the Luttinger model and treating irrelevant operators associated with band curvature effects. This approach is able to describe the width of the on-shell peak and the high-frequency tail at finite magnetic field. Integrability is shown to affect the low-energy effective model at zero field, with consequences for the line shape. The power-law singularities at the thresholds of the particle-hole continuum are investigated using an analogy with the X-ray edge problem. Using methods of Bethe ansatz and conformal field theory, I compute the exact exponents for the edge singularities of the dynamical structure factor. The same methods are used to study the long-time asymptotic behavior of the spin self-correlation function, which is shown to be dominated by a high-energy excitation.
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18

Stenberg, Kristoffer, i Henrik Wikerman. "Evaluating Regime Switching in Dynamic Conditional Correlation". Thesis, KTH, Matematisk statistik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134214.

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This paper provides a comparative study of the Dynamic Conditional Correlation model introduced by Engle (2002) and the Independent Switching Dynamic Conditional Correlation model introduced by Lee (2010) by evaluating the models for a set of known correlation processes. The evaluation is also extended to cover empirical data to assess the practical performance of the models. The data include the price of gold and oil, the yield on benchmark 10 year U.S. Treasury notes and the Euro-U.S. dollar exchange rate from January 2007 to December 2009. In addition, a general description of the difficulties of estimating correlations is presented to give the reader a better understanding of the limitations of the models. From the results, it is concluded that there is no general superiority of neither the IS-DCC model nor the DCC model, except for very short-lived correlation shifts. For short-lived shifts, the IS-DCC model outperforms in both detecting and measuring correlations. However, this paper recommends that these models are used in combination with a qualitative study in empirical situations to better understand the underlying correlation dynamics.
Denna rapport innehåller en jämförande studie av den dynamiska korrelationsmodellen DCC som presenterades av Engle (2002) och den regimskiftande dynamiska korrelationsmodellen IS-DCC vilken presenterades av Lee (2010). Studien är uförd genom att jämföra modellerna för en uppsättning kända korrelationsprocesser samt för empiriska data. Den empiriska datan inkluderar priset på guld och olja , referensavkastningen på amerikanska statsobligationer med 10 årig löptid samt valutakursen mellan Euro och den amerikanska dollarn under perioden januari 2007 till december 2009. Utöver jämförelsen ges även en allmän beskrivning av svårigheterna med att uppskatta korrelation för att ge läsaren en utökad förståelse av modellernas begränsningar. Resultaten visar att varken DCC eller IS-DCC modellen är bättre än den andra förutom vid snabba korrlationsskiften. För snabba korrelationsskiften visar sig IS-DCC modellen bättre både vad gäller att flagga för dessa skiften som att uppskatta korrelationen. Slutligen rekommenderas ändå att båda dessa modeller används i kombination med en kvalitativ studie i praktiska situationer för att ge en omfattande förståelse av tidsvarierande korrelationsdynamik.
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19

Kaparis, Stathis. "Dynamic conditional correlation modelling for asset returns". Thesis, Imperial College London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536010.

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20

Kang, Zhongbo. "QCD quantum correlation and multi-parton dynamic". [Ames, Iowa : Iowa State University], 2009.

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21

Ries, Jonas. "Advanced Fluorescence Correlation Techniques to Study Membrane Dynamics". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1219846317196-73420.

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Fluorescence Correlation Spectroscopy (FCS) is a powerful tool to measure important physical quantities such as concentrations, diffusion coefficients, diffusion modes or binding parameters, both in solution and in membranes. However, it can suffer from severe artifacts, especially in non-ideal systems. Here we develop several novel implementations of FCS which overcome these limitations and facilitate accurate and quantitative determination of dynamic parameters in membranes. Two-focus FCS with camera-detection allows for accurate and calibration-free determination of diffusion coefficients. Confocal FCS using a laser scanning microscope provides an unprecedented positioning accuracy which enabled us to study, for the first time with FCS, dynamics in bacterial membranes. Scanning FCS with a scan path perpendicular to the membrane plane allows to correct for instabilities permitting long measurement times necessary to study slow diffusion. It can easily be extended to measure calibration-free diffusion coefficients with two-focus scanning FCS and to quantify binding with dual color scanning FCS. Spectral crosstalk can be avoided effectively by using alternating excitation. Using this method we were able to perform measurements in systems previously not accessible with FCS, such as yeast cell membranes or membranes of living zebrafish embryos. Line-scan FCS with a scan path in the membrane plane uses the parallel acquisition along the line to increase the statistical accuracy and decrease the measurement times. Knowledge of the scan speed serves as an internal calibration, enabling accurate diffusion and concentration measurements within seconds, hardly affected by photobleaching. Both realizations of scanning FCS can be easily implemented with commercial laser scanning microscopes. Often, a fluorescence background around the membrane cannot be avoided. The high surface selectivity needed in this case can be achieved efficiently by using a novel objective for FCS, the supercritical angle objective, which produces a very flat and laterally confined detection volume. Another technique with similar surface selectivity is FCS with total internal reflection excitation (TIRFCS). Due to the lack of a correct model, the accurate analysis of TIR-FCS data was previously not possible. In this work we develop such a model, enabling quantitative measurements of membrane dynamics with TIR-FCS. The novel FCS techniques developed here will have a high impact on the use of FCS to address key questions in biological systems, previously inaccessible by other methods
Fluoreszenz-Korrelations-Spektroskopie (FCS) ist eine mächtige Methode, um wichtige physikalische Parameter wie Konzentrationen, Diffusionskoeffizienten, Diffusionsarten oder Bindungsparameter in Lösung und in Modell- oder Zellmembranen zu bestimmen. In nichtidealen Systemen ist FCS fehleranfällig. In dieser Arbeit entwickeln wir mehrere neuartige Realisierungen von FCS, welche diese Fehlerquellen umgehen und die genaue und quantitative Messung dynamischer Parameter in Membranen ermöglichen. Zwei-Fokus FCS mit Kamera-Detektion erlaubt eine genaue und kalibrationsfreie Messung von Diffusionskoeffizienten. Konfokale FCS mit einem Laserscanningmikroskop besitzt eine bislang unerreichte Positionsgenauigkeit, welche uns erstmals dynamische Messungen in Bakterienmembranen mit FCS ermöglichte. Scanning FCS mit einem Scanweg senkrecht zur Membran ermöglicht eine Korrektur von Instabilitäten und damit lange Messzeiten, die zur Bestimmung langsamer Diffusionskoeffizienten notwendig sind. Eine Erweiterung zur kalibrationsfreien Messung von Diffusionskoeffizienten mit Zwei-Fokus Scanning FCS und von Bindungsparametern mit Zwei-Farben Scanning FCS ist einfach. Mit diesen Methoden konnten wir in Systemen messen, die bislang FCS nicht zugänglich waren, so in Hefezellmembranen oder in Membranen lebender Zebrafischembryonen. Line-scan FCS besitzt einen Scanweg parallel zur Membran. Die parallele Messung entlang der ganzen Linie führt zu einer deutlichen Verbesserung der Statistik und damit zu kurzen Messzeiten. Die Kenntnis der Scangeschwindigkeit dient einer internen Kalibration und erlaubt eine akkurate Bestimmung von Diffusionskoeffizienten und Konzentrationen innerhalb weniger Sekunden, kaum beeinflusst vom Bleichen von Fluorophoren. Beide Arten von Scanning FCS können mit einem kommerziellen Laserscanningmikroskop realisiert werden. Häufig kann bei FCS Messungen ein fluoreszierender Hintergrund nicht vermieden werden. Hier ist eine hohe Oberflächenselektivitiät nötig, welche effizient mit einem neuartigen Objektiv erreicht werden kann. Dieses Supercritical Angle-Objektiv erzeugt ein sehr flaches und lateral begrenztes Detektionsvolumen. Eine weitere Methode mit einer ähnlich guten Oberflächenselektivität ist FCS mit Anregung über totale interne Reflektion (TIR-FCS). Bislang war eine quantitative Analyse der TIR-FCS Daten kaum möglich, da keine ausreichend genaue theoretische Beschreibung existierte. In dieser Arbeit entwickeln wir ein akkurates Modell, welches quantitative Messungen mit TIR-FCS erlaubt. Die hier entwickelten neuartgien FCS-Techniken ermöglichen die Untersuchung biologischer Fragestellungen, welche bislang keiner anderen Methode zugänglich sind
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22

Holland, Mark Paul. "Physical measures for chaotic dynamical systems and decay of correlations". Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247950.

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23

Shakil, Sadia. "Windowing effects and adaptive change point detection of dynamic functional connectivity in the brain". Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/55006.

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Evidence of networks in the resting-brain reflecting the spontaneous brain activity is perhaps the most significant discovery to understand intrinsic brain functionality. Moreover, subsequent detection of dynamics in these networks can be milestone in differentiating the normal and disordered brain functions. However, capturing the correct dynamics is a challenging task since no ground truths' are present for comparison of the results. The change points of these networks can be different for different subjects even during normal brain functions. Even for the same subject and session, dynamics can be different at the start and end of the session based on the fatigue level of the subject scanned. Despite the absence of ground truths, studies have analyzed these dynamics using the existing methods and some of them have developed new algorithms too. One of the most commonly used method for this purpose is sliding window correlation. However, the result of the sliding window correlation is dependent on many parameters and without the ground truth there is no way of validating the results. In addition, most of the new algorithms are complicated, computationally expensive, and/or focus on just one aspect on these dynamics. This study applies the algorithms and concepts from signal processing, image processing, video processing, information theory, and machine learning to analyze the results of the sliding window correlation and develops a novel algorithm to detect change points of these networks adaptively. The findings in this study are divided into three parts: 1) Analyzing the extent of variability in well-defined networks of rodents and humans with sliding window correlation applying concepts from information theory and machine learning domains. 2) Analyzing the performance of sliding window correlation using simulated networks as ground truths for best parameters’ selection, and exploring its dependence on multiple frequency components of the correlating signals by processing the signals in time and Fourier domains. 3) Development of a novel algorithm based on image similarity measures from image and video processing that maybe employed to identify change points of these networks adaptively.
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24

Charles, Adam Shabti. "Dynamics and correlations in sparse signal acquisition". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53592.

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One of the most important parts of engineered and biological systems is the ability to acquire and interpret information from the surrounding world accurately and in time-scales relevant to the tasks critical to system performance. This classical concept of efficient signal acquisition has been a cornerstone of signal processing research, spawning traditional sampling theorems (e.g. Shannon-Nyquist sampling), efficient filter designs (e.g. the Parks-McClellan algorithm), novel VLSI chipsets for embedded systems, and optimal tracking algorithms (e.g. Kalman filtering). Traditional techniques have made minimal assumptions on the actual signals that were being measured and interpreted, essentially only assuming a limited bandwidth. While these assumptions have provided the foundational works in signal processing, recently the ability to collect and analyze large datasets have allowed researchers to see that many important signal classes have much more regularity than having finite bandwidth. One of the major advances of modern signal processing is to greatly improve on classical signal processing results by leveraging more specific signal statistics. By assuming even very broad classes of signals, signal acquisition and recovery can be greatly improved in regimes where classical techniques are extremely pessimistic. One of the most successful signal assumptions that has gained popularity in recet hears is notion of sparsity. Under the sparsity assumption, the signal is assumed to be composed of a small number of atomic signals from a potentially large dictionary. This limit in the underlying degrees of freedom (the number of atoms used) as opposed to the ambient dimension of the signal has allowed for improved signal acquisition, in particular when the number of measurements is severely limited. While techniques for leveraging sparsity have been explored extensively in many contexts, typically works in this regime concentrate on exploring static measurement systems which result in static measurements of static signals. Many systems, however, have non-trivial dynamic components, either in the measurement system's operation or in the nature of the signal being observed. Due to the promising prior work leveraging sparsity for signal acquisition and the large number of dynamical systems and signals in many important applications, it is critical to understand whether sparsity assumptions are compatible with dynamical systems. Therefore, this work seeks to understand how dynamics and sparsity can be used jointly in various aspects of signal measurement and inference. Specifically, this work looks at three different ways that dynamical systems and sparsity assumptions can interact. In terms of measurement systems, we analyze a dynamical neural network that accumulates signal information over time. We prove a series of bounds on the length of the input signal that drives the network that can be recovered from the values at the network nodes~[1--9]. We also analyze sparse signals that are generated via a dynamical system (i.e. a series of correlated, temporally ordered, sparse signals). For this class of signals, we present a series of inference algorithms that leverage both dynamics and sparsity information, improving the potential for signal recovery in a host of applications~[10--19]. As an extension of dynamical filtering, we show how these dynamic filtering ideas can be expanded to the broader class of spatially correlated signals. Specifically, explore how sparsity and spatial correlations can improve inference of material distributions and spectral super-resolution in hyperspectral imagery~[20--25]. Finally, we analyze dynamical systems that perform optimization routines for sparsity-based inference. We analyze a networked system driven by a continuous-time differential equation and show that such a system is capable of recovering a large variety of different sparse signal classes~[26--30].
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25

Quintero, Quiroz Carlos Alberto. "Temporal correlations and dynamical transitions in semiconductor lasers with optical feedback". Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/405941.

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Optical excitable systems that mimic neuronal behavior have potential to be building-blocks of novel, ultra-fast, neuron-inspired photonic information processing systems. In particular, semiconductor lasers with optical feedback (SLOF) can emit optical spikes with temporal correlations resembling those present in neuronal spike. SLOF can also generate a rich variety of dynamical behaviors, and thus, are ideal testbeds for studying dynamical transitions and testing novel analysis tools. In order to advance in the development of neuron-inspired laser processors it is important to understand how SLOF represent (or encode), in the sequence of spikes, an external input. It is also important to understand how the different dynamic regimes develop, and how they are affected by external perturbations. Hence, the aim of this Thesis is the study of temporal correlations and dynamical transitions in the dynamics of an SLOF. To do this, we perform experiments, model simulations, and use a symbolic method to analyze the obtained intensity time-series. First, we investigate how the spiking laser output encodes a weak periodic input that is implemented via direct modulation of the laser pump current. Experimental sequences of optical spikes were recorded and analyzed by using the ordinal symbolic methodology that identifies and characterizes serial correlations in data sets. When changing the frequency and amplitude of the modulation, transitions among different locking regimes are detected in the form of changes in the statistics of the ordinal patterns. A good qualitative agreement is also found with simulations of the Lang and Kobayashi model. Second, we identify the onset of different dynamical regimes that occur as the laser pump current increases. We apply three analysis tools that allow quantifying various aspects of the dynamical regime transitions. The first method is based on the analysis of the standard deviation of the intensity time-series, recorded with different oscilloscope sampling rates; the second method relies on the analysis of the number of spikes as a function of the threshold used to define the spikes. The third method is based on the ordinal analysis of the inter-spike-intervals. These tools allow us to quantitatively detect the onset of two different dynamical regimes, know as low-frequency fluctuations (LFF), and coherence collapse (CC). We also analyzed the transition from a noise-dominated regime to a more deterministic (less stochastic) dynamics. For this study, in addition to the experimental laser system (an SLOF), we used as numerical examples the logistic map and the Rössler chaotic system. We find that, when the noise is strong, the permutation entropy (computed from the probabilities of the ordinal patterns) increases faster than linearly. By comparing the results of these three systems, we discuss the possibility of determining, from time series analysis, whether the underlying dynamics is dominated by noise or by deterministic processes. The results reported in this Thesis are relevant in a number of ways. The methodologies developed allow detecting parameter regions of noisy locking to an external weak periodic input and may be useful to investigate other forced excitable systems. In addition, the methods developed to detect the onset of different regimes can be valuable for analyzing regime transitions in many real world systems. Finally, the methodology for determining, for observed data, whether the underlying dynamic is mainly driven by noise or by deterministic effects can also be used in multidisciplinary applications (finances, geosciences, social systems,etc.).
Los sistemas ópticos excitables capaces de imitar el comportamiento neuronal, pueden contribuir al desarrollo de nuevos sistemas fotónicos de procesamiento de información ultra-rápidos, inspirados en el procesamiento neuronal de información. En particular, los láseres semiconductores con retroalimentación óptica (LCRO), pueden emitir pulsos ópticos con correlaciones temporales similares a las que presentan las series disparos neuronales. Un LCRO puede generar una gran variedad de comportamientos dinámicos, por lo tanto, es ideal para estudiar transiciones dinámicas y probar nuevas herramientas de análisis de datos. Para avanzar en el desarrollo de procesadores basados en láseres de semiconductor que emulen neuronas, es importante entender como estos láseres codifican un estimulo externo en la secuencia de pulsos de intensidad emitidos; como se desarrollan los diferentes regímenes dinámicos y como se ven afectados por perturbaciones externas. El objetivo de esta Tesis es el estudio de las correlaciones temporales y de las transiciones dinámicas en un LCRO. Para ello se ha realizado experimentos y simulaciones, y se han analizado los datos obtenidos empleando una técnica de analisis simbólico. En primer lugar, investigamos como los pulsos emitidos por el láser codifican una señal de entrada periódica débil, suministrada a través de modulación directa de la corriente de inyección del láser. Se han registrado secuencia experimentales de pulsos opticos y se han analizado usando el analisis simbólico ordinal. Dicho método, las identifica y caracteriza a través de de un conjunto de datos. Las variaciones en frencuencia y amplitud de modulación de la señal introducida producen transiciones entre diferentes regímenes del láser, que se detectan mediante cambios en la estadística del análisis simbólico. Los resultados obtenidos de las simulaciones usando el modelo de Lang-Kobayashi, concuerdan cualitativamente con las observaciones experimentales. En segundo lugar, hemos aplicado tres herramientas de análisis que permiten cuantificar diversos aspectos de las transiciones de régimen dinámico. De tal modo, hemos identificado el inicio de diferentes regímenes que se producen al aumentar la corriente de inyección del láser. El primer método se basa en el análisis de la desviación estándar de las series temporales de la intensidad, registradas con diferentes frecuencias de muestreo del osciloscopio; el segundo método, se basa en el análisis del número de pulsos que cruzan un determinado un umbral, en función del umbral utilizado. El tercer método, consiste en el análisis ordinal de los distintos intervalos temporales entre pulsos. Estas herramientas detectan cuantitativamente el inicio de dos regímenes dinámicos, conocidos como fluctuaciones de baja frecuencia (LFF) y colapso de coherencia (CC). También hemos analizado la transición de un régimen dominado por ruido hacia una dinámica más determinista. Para este estudio, además del sistema experimental (un LCRO), hemos utilizado como ejemplos numéricos el mapa logístico y el sistema de Rössler. Encontramos que, cuando el nivel de ruido es alto, la entropía de permutación (calculada a partir de las probabilidades de patrones ordinales) aumenta mas rápido que linealmente y discutimos la posibilidad de determinar, a partir del análisis de series temporales, si la dinámica subyacente está dominada por ruido o por un proceso determinísta. Los resultados presentados en esta Tesis son relevantes en varios aspectos. Las metodologías desarrolladas, pueden ser útiles para investigar otros sistemas excitables porque permiten detectar regiones de “loking” producidos por una perturbación externa periódica y débil. Además, los métodos desarrollados, pueden detectar cualitativamente el inicio de diferentes regímenes dinámicos y pueden ser valiosos para analizar transiciones entre regímenes en otros sistemas. Por último, la metodología propuesta para determinar en los datos observados, si la dinámica subyacente es principalmente dominada por el ruido o por efectos deterministas, puede también tener aplicaciones multidisiplinarias
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26

Lee, Jin Kuk. "Surface Dynamics of Partially Tethered Polymer Films". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1357660313.

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27

Zhang, Luyuan. "Ultrafast Protein Hydration Dynamics Probed by Intrinsic Tryptophan". The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1276524825.

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28

McGurk, Stephen James. "Scalar and vector correlations in molecular collision dynamics". Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2959.

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This thesis concerns the fundamental scalar and vector attributes of molecular collisions. A translationally relaxed sample of fully state-selected and rotationally anisotropic CN(A² ∏,v = 4, jFɛ) was prepared within a thermal bath (~298 K) of partner gas (either Ar, N2, O2 or CO2) by ns-pulsed laser excitation. The collisional evolution of the prepared polarised rotational angular momentum was monitored using highresolution frequency modulation spectroscopy (FMS). The total removal and depolarisation of oriented or aligned rotational angular momentum was measured in CN(A² ∏,v = 4, j = 2.5, 3.5, 6.5, 11.5, 13.5, and 18.5, F1e). The state-to-state rotational energy transfer (RET) and orientation transfer from CN(A² ∏,v = 4, j = 6.5 F1e or j = 10.5 F2f) to ∆j ≤ |5| was investigated. The results for the CN(A² ∏,+Ar system generally agree very well with complementary exact quantum scattering (QS) calculations on the best available ab initio potential energy surfaces (PESs). For all systems, a three-level multiple-collision kinetic model satisfactorily reproduces the observed removal of population and polarisation. Elastic depolarisation is found to be a relatively minor pathway relative to population removal and inelastic depolarisation, as confirmed by complete master equation (ME) simulations for CN(A² ∏, v=4, j = 6.5 F1e)+Ar. The total removal efficiencies lie in the order CO2 > N2 > O2 > Ar, loosely correlated with long-range attractive forces. O2 and CO2 exhibit rapid removal channels in addition to RET, likely to be electronic quenching to CN(X2∑+). There are substantial parity-dependent alternations with Dj in state-to-state RET and polarisation transfer, sufficient for a striking change in sign of orientation for specific transitions. This is attributed to the near-homonuclear nature of CN(A² ∏) and consequent even character of the PESs. QS calculations indicate that the dynamics of parity-conserving and changing transitions differ fundamentally. A preference for spinorbit conservation, strongest for Ar, comes from the near-Hund’s case-(a) character of CN(A² ∏) at low-j. Despite the additional dimensions available, the qualitatively similar behaviour of the molecular partners with Ar suggests that these systems have comparable interaction potentials with CN(A² ∏). Therefore, small centrosymmetric molecules, such as N2, O2 and CO2, may approximately be treated as spherical targets. This is supported by recent spherically-averaged CN(A² ∏)-N2 PESs and associated QS calculations from the literature.
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29

Camati, Patrice Audibert [UNESP]. "A study of the dynamics of quantum correlations". Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/108887.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Neste trabalho, apresentamos uma introdução à teoria da informação quântica. Antes de lidarmos com a informação quântica propriamente dita, desenvolvemos alguns assuntos preliminares, a teoria clássica da informação e conceitos relevantes em dinâmica de sistemas quânticos. Depois, de?nimos medidas de correlações quânticas, concorrência e discórdia quântica, e estudamos sua evolução dinâmica quando o acoplamento do sistema com o ambiente é modelado como aleatório. Concluímos que um ambiente aleatório impõe uma perda permanente nas correlações do sistema
In this work, we present an introduction to the quantum information theory. Before dealing with quantum information we develop some necessary tools, the classical information theory and some important concepts in quantum dynamics. We de?ne measures of quantum correlations, concurrence and quantum discord, and study their dynamical evolution when the coupling between the system and environment is considered random. We conclude that a random environment imposes permanent loss of correlations to the system
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30

Kambili, Agapi. "Lattice dynamics and electron correlations in mesoscopic systems". Thesis, Lancaster University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310459.

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31

Camati, Patrice Audibert. "A study of the dynamics of quantum correlations /". São Paulo, 2014. http://hdl.handle.net/11449/108887.

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Orientador: Gastão Inácio Krein
Banca: Diógenes Galetti
Banca: Roberto Menezes Serra
Resumo: Neste trabalho, apresentamos uma introdução à teoria da informação quântica. Antes de lidarmos com a informação quântica propriamente dita, desenvolvemos alguns assuntos preliminares, a teoria clássica da informação e conceitos relevantes em dinâmica de sistemas quânticos. Depois, definimos medidas de correlações quânticas, concorrência e discórdia quântica, e estudamos sua evolução dinâmica quando o acoplamento do sistema com o ambiente é modelado como aleatório. Concluímos que um ambiente aleatório impõe uma perda permanente nas correlações do sistema
Abstract: In this work, we present an introduction to the quantum information theory. Before dealing with quantum information we develop some necessary tools, the classical information theory and some important concepts in quantum dynamics. We define measures of quantum correlations, concurrence and quantum discord, and study their dynamical evolution when the coupling between the system and environment is considered random. We conclude that a random environment imposes permanent loss of correlations to the system
Mestre
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32

McCrudden, Garreth. "Vector correlations in gas-phase inelastic collision dynamics". Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:967fbe54-98a9-48e9-a0b2-707811804d7a.

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This thesis presents a joint experimental and theoretical study of vector correlations in the electronically, vibrationally, and rotationally inelastic collisions of simple molecules with rare-gas atoms. In the first instance, empirical and calculated data are presented for rotationally inelastic scattering in the NO(X)+Ar and ND3(X̃)+Ar systems at collision energies in the range 405-2210 cm-1. These experiments - the first to be conducted on a newly commissioned crossed-molecular beam machine - measured the k-k' correlation, i.e. that between the vectors describing the relative velocities before and after collision, respectively. The empirical data were subjected to rigorous comparison with both quantum-mechanical and quasi-classical trajectory (QCT) calculations. For both the NO(X)+Ar and ND3(X̃)+Ar systems, there is generally good agreement between experiment and theory at all four collision energies investigated. Two chapters of this thesis focus on the development of trajectory surface-hopping (TSH) QCT models of the OH(A, v = 0)+Kr and OH(A, v = 0)+Xe systems. Experimental data relating to scalar quantities (rotational energy transfer (RET) and electronic quenching) and to the j-j' correlation (which quantifies the depolarisation of the angular momentum of the OH(A) radical) are compared to variable-collision-energy TSH QCT calculations in which the length of the OH bond is fixed. The algorithms involve all three PESs of the OH(A/X)+Kr system, and the full range of electrostatic and roto-electronic mechanisms that couple them, for the first time. The most complete model succeeded in accounting for 93% of experimentally observed quenching. For the OH(A/X)+Xe system, coupling matrix elements were estimated from those of OH(A/X)+Kr, and the most complete model recovered 63% of experimentally observed quenching. This thesis also presents a novel theoretical study of rotationally inelastic dynamics in the OH(A, v = 1)+Kr system. Provisional results from adiabatic calculations in which the OH bond length is allowed to vary over the course of a trajectory are presented alongside experimental data that were reported previously. To date, these calculations continue to underestimate the extent of empirical RET data. Reasons for the observed discrepancy, and suggestions to resolve it, are outlined in detail.
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33

Burdett, Yan Liu. "Correlation of Software Quality Metrics and Performance". NSUWorks, 2012. http://nsuworks.nova.edu/gscis_etd/109.

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Performance is an aspect of software quality that is often not considered at early stages of software design. Common approaches to performance analysis include utilizing profiling tools after the software has been developed to find bottlenecks and executing simulation models that are either manually constructed or derived from UML design diagrams. Many projects attempt to correct performance issues by adding more powerful hardware instead of attacking the root cause. Software metrics have been used to predict many aspects of software quality such as maintainability and fault-tolerance by correlation and regression analysis. Metrics proposed by Chidamber and Kemerer, also known as the CK metric suite, have been studied extensively in software quality model analyses. These studies examined maintainability, fault tolerance, error proneness, and scalability of the software as it evolved through time. Correlations were made between metrics and the likely quality models they represented. Other metrics such as Cyclomatic Complexity by McCabe and class couplings by Martin have also been used in quality predictions. No research has been conducted to analyze relationship between performance and metrics. The goal of this research was to construct a decision tree that used software metrics to forecast performance characteristics. The relationship between metrics and performance was derived by correlation between static code metrics and three runtime variables: number of objects, method call frequency, and average method call lengths on selected software benchmarks. The decision tree was constructed using the C4.5 algorithm implemented in the WEKA software. Pearson correlation coefficients were obtained for the combined datasets from all benchmarks. The decision trees and Pearson statistics showed that weighted methods per class (WMC), total lines of code (TLOC), and coupling between objects (CBO) have significant correlation with software performance. WMC showed positive correlation with number of objects and calls. CBO correlated positively with average method call lengths and negatively with number of objects. TLOC correlated positively with number of calls.
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34

Radiom, Milad. "Correlation Force Spectroscopy for Single Molecule Measurements". Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/49677.

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This thesis addresses development of a new force spectroscopy tool, correlation force spectroscopy (CFS), for the measurement of the mechanical properties of very small volumes of material (molecular to µm³) at kHz-MHz time-scales. CFS is based on atomic force microscopy (AFM) and the principles of CFS resemble those of dual-trap optical tweezers. CFS consists of two closely-spaced micro-cantilevers that undergo thermal fluctuations. Measurement of the correlation in thermal fluctuations of the two cantilevers can be used to determine the mechanical properties of the soft matter, e.g. a polymeric molecule, that connects the gap between the two cantilevers. Modeling of the correlations yields the effective stiffness and damping of the molecule. The resolution in stiffness is limited by the stiffness of the cantilever and the frequency by the natural frequency of the cantilevers, but, importantly, the damping resolution is not limited by the damping of the cantilever, which has enabled high-resolution measurements of the internal friction of a polymer. The concept of CFS was originally presented by Roukes' group in Caltech [Arlett et al., Lecture Notes in Physics, 2007]; I developed the first practical versions of CFS for experimentation, and have used it in two applications (1) microrheology of Newtonian fluids and (2) single molecule force spectroscopy. To understand the correlation in thermal fluctuations of two cantilevers I initially validated the theoretical approach for analyzing correlation in terms of deterministic model using the fluctuation-dissipation theorem [Paul and Cross, PRL, 2004]. I have shown that the main advantages of such correlation measurements are a large improvement in the ability to resolve stiffness and damping. Use of CFS as a rheometer was validated by comparison between experimental data and finite element modeling of the deterministic vibrations of the cantilevers using the known viscosity and density of fluids. Work in this thesis shows that the data can also be accurately fitted using a simple harmonic oscillator model, which can be used for rapid rheometric measurements, after calibration. The mechanical properties of biomolecules such as dextran and single stranded DNA (ssDNA) are also described. CFS measurements of single molecule properties of ssDNA reveal the internal friction of the molecule in solution.
Ph. D.
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35

Precup, Ovidiu Vasile. "New methods for measuring correlation and modelling asset price dynamics". Thesis, London School of Economics and Political Science (University of London), 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.551341.

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The first two chapters of the thesis are a comparative study of several methods for correlation estimation from high-frequency data. These range from the well established Pearson correlation coefficient and Spearman's rho to the more recently proposed realised correlation and Fourier method estimators. Measuring correlation from high-frequency data is impeded by two main problems. One problem stems from the asynchronous and non-homogeneous nature of the time series and the other is caused by a market microstructure effect called the "Epps effect". The performance of each correlation method in dealing with both problems is first assessed with simulated data and then with real time series spanning 14 years of trades in S&P1 00 stocks. The correlation matrices thus obtained are analysed with the aid of Random Matrix Theory and network analysis tools such as Minimum Spanning Trees. In the third chapter, network analysis tools are applied to the Italian interbank payments system. The objective is to analyse the network topology of the system in order to ascertain the differences in the activities of banks of different sizes and the evolution of their connectivity structure over time. This helps in assessing the stability of the banking system and the efficiency of the interbank market. The fourth chapter introduces a new class of stochastic processes called Ito semi-diffusions as an alternative modelling framework for asset price dynamics. These models provide a better fit for the distributional properties of asset prices whilst maintaining analytical tractability. Numerous examples are given together with an illustration of a pricing method for the valuation of contingent claims. In the final chapter a stochastic control problem that arises in the context of commodity storage valuation is considered. The model's operational characteristics can be associated with different types of inventories such as hydro-electric reservoirs or gas storage facilities. Under suitable assumptions, it is shown that the optimal storage strategy depends only on the planning horizon and on the amount of stored commodity but not on the actual commodity price.
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36

Mattiussi, Vanessa. "Non parametric estimation of high-frequency volatility and correlation dynamics". Thesis, City University London, 2010. http://openaccess.city.ac.uk/12095/.

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This thesis addresses the problem of quantitatively evaluating the temporal dynamics that characterized financial time series. In particular, we perform an accurate analysis of the Fourier estimator, a newly proposed nonparametric methodology to measure ex-post volatility and cross-volatilities as functions of time, when financial assets are observed at different highfrequency levels over the day. The estimator has the peculiar feature to employ the observed data in their original form, therefore exploiting all the available information in the sample. We first show how to considerably improve the numerical performance of the Fourier method making possible the analysis of large sets of data, as it is usually the case with high-frequency series. Secondly, we use Monte Carlo simulation methods to study the behavior of three driving parameters in the estimation procedure, when the effects of both irregular sampling and microstructure noise are taken into account. The estimator is showed to be particularly sensitive to one of these quantities, which is in turn used to control the contribution of the above effects. Integrated financial correlation is also analyzed within two distinct comparative studies that involve other multivariate measures. The analysis is then extended to consider the entire evolution of the underlying correlation process. Finally, we propose a new class of nonparametric spot volatility estimators, which is showed to include the Fourier method as a particular case. The full limit theory under infill asymptotics in the pure diffusive settings of the class is derived. Empirical evidence in support of our conclusions is also provided.
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37

Chang, Patrick. "High-frequency correlation dynamics: Is the Epps effect a bias?" Master's thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33682.

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We tackle the question of whether Trade and Quote data from high-frequency finance are representative of discrete connected events, or whether these measurements can still be faithfully represented as random samples of some underlying Brownian diffusion in the context of modelling correlation dynamics. In particular, if the implicit notion of instantaneous correlation dynamics that are independent of the time-scale a reasonable assumption. To this end, we apply kernel averaging non-uniform fast Fourier transforms in the context of the Malliavin-Mancino integrated and instantaneous volatility estimators to speed up the estimators. We demonstrate the implicit time-scale investigated by the estimator by comparing it to the theoretical Epps effect arising from asynchrony. We compare the Malliavin-Mancino and Cuchiero-Teichmann Fourier instantaneous estimators and demonstrate the relationship between the instantaneous Epps effect and the cutting frequencies in the Fourier estimators. We find that using the previous tick interpolation in the Cuchiero-Teichmann estimator results in unstable estimates when dealing with asynchrony, while the ability to bypass the time domain with the Malliavin-Mancino estimator allows it to produce stable estimates and is therefore better suited for ultra high-frequency finance. We derive the Epps effect arising from asynchrony and provide a refined approach to correct the effect. We compare methods to correct for the Epps effect arising from asynchrony when the underlying process is a Brownian diffusion, and when the underlying process is from discrete connected events (proxied using a D-type Hawkes process). We design three experiments using the Epps effect to discriminate the underlying processes. These experiments demonstrate that using a Hawkes representation recovers the empiricism reported in the literature under simulation conditions that cannot be achieved when using a Brownian representation. The experiments are applied to Trade and Quote data from the Johannesburg Stock Exchange and the evidence suggests that the empirical measurements are from a system of discrete connected events where correlations are an emergent property of the time-scale rather than an instantaneous quantity that exists at all time-scales.
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38

DI, BONA MELODY. "Advanced Fluorescence Correlation Spectroscopy for The Study of Nuclear Dynamics". Doctoral thesis, Università degli studi di Genova, 2019. http://hdl.handle.net/11567/941688.

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Chromatin is a macromolecule mainly composed by DNA and histones. Chromatin not only has the function of compacting the DNA in order to make it fit into the nucleus, but also plays an active role in the regulation of all biological processes using DNA as template in eukaryotes, such as transcription, DNA replication and DNA repair. The architectural organization of chromatin can play an important role in gene expression by regulating the diffusion of molecules via binding interactions and molecular crowding. In this respect, understanding how variations of chromatin architecture affect nuclear dynamics is of fundamental importance. Among the techniques that are able to probe the nuclear interior, fluorescence microscopy is sensitive, specific and does not require strong manipulation of the sample, allowing also measurements to be performed in living samples. But not all the fluorescence microscopy techniques have the adequate temporal resolution to follow the dynamics of the nuclear environment. Fluorescence Correlation Spectroscopy (FCS) is able to probe chromatin accessibility and molecular crowding in live cells by measuring fast diffusion of molecules in the range between microseconds and milliseconds. In particular, single point FCS (spFCS) has a high temporal resolution but lacks spatial information. Conversely, spatially-resolved methods, like scanning FCS, have in general limited temporal resolution. The aim of this thesis is to overcome these limitations through the Intensity Sorted FCS technique. This technique is able to probe fast molecular diffusion in nuclear environment distinguishing between different regions of the space at a high temporal resolution. This achievement is due to the idea of dividing a whole FCS measurement, performed through a slow scan of the beams, into short temporal segment: each segment is analyzed and for each one an ACF is calculated. Then the ACFs are sorted into two populations basing on the intensity of a reference trace, that specifically distinguish the two nuclear regions probed: for each set of ACFs corresponding to a region, the average ACF is calculated. In this way it is possible to retrieve statistically robust information about diffusion in two distinct nuclear regions in the same measurement.
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39

Perez, Waldo Flores, Jorge Chavez Cerdena, Gary Duran Ramirez i Maggie Martinelli Montoya. "Correlation of dynamic probing light (DPL) and standard penetration test (SPT) for sandy soil of alluvial origin". Institute of Electrical and Electronics Engineers Inc, 2020. http://hdl.handle.net/10757/656568.

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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.
In geotechnical studies, the dynamic probing light (DPL) turns out to be an alternative method to the Standard Penetration test (SPT) for the determination of soil parameters. The requirement of various regulations for correlating both tests in the same field and not establishing a methodology to carry it out, limits the practical scope of dynamic probing light. Thus, this research presents a correlation methodology between the dynamic probing light (DPL) and the Standard Penetration test (SPT) specifically for sandy soils (SP and SP-SM) located in an area of Chilca, located in Cañete. - Lima Peru. For the analysis, more than 400 data pairs were used, obtaining two linear correlations between the count blow of Standard Penetration-NSPT test and the dynamic probing light method-N10, which presented an adjustment correlation between 84% and 87 %.
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40

DUARTE, ANDRE SENNA. "THE ECONOMIC VALUE OF CONSTANT AND DYNAMIC CONDITIONAL CORRELATION MODEL". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10613@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
Em Fleming, Kirby e Ostdiek (2001), encontram-se evidências de que a utilização de modelos de previsão da volatilidade, possui valor econômico significante quando se compara simplesmente com a matriz de variância incondicional, num arcabouço de otimização de portfólio. Indo além, este trabalho propõem averiguar se os modelos mais complexos de Correlação Condicional Constante (CCC) e Dinâmica (DCC) sugeridos respectivamente por Bollerslev (1990) e Engle (2002) podem oferecer melhores resultados. Os resultados encontrados são dependentes da preferência do investidor. Um investidor mais avesso ao risco, terá maior utilidade ao empregar o modelo DCC e CCC quando comparado ao simples modelo da média móvel com decaimento exponencial, popularizados por RiskMetrics. Isso ocorre porque os modelos DCC e CCC apresentam desvio padrão e retorno geralmente inferiores. Ainda, não é possível afirmar como em Fleming, Kirby e Ostdiek (2001) que a utilização de modelos de previsão da volatilidade, possui valor econômico significante.
At Fleming, Kirby e Ostdiek (2001), evidences are found that volatility timming models, have signicant economic value when comparing with the simple unconditional variance matrix, in a framework of portfolio optimization. Going further, this work analyze if the more complex Constant (CCC) and Dynamic (DCC) Conditional Corrrelation models, suggested respectivily by Bollerslev (1990) and Engle (2002) can have a higher performance. The results found depend on the investor´s preference. A more risk averse investor has a higher utility level employing the DCC and CCC models when comparing with the simple exponencial moving avarage model, popularized by RiskMetrics. This happens because the DCC and CCC models usually have smaller standard deviation and return. Futhermore, it is not possible to assert, like at Fleming, Kirby e Ostdiek (2001), that volatility timming models have higher economic value.
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41

Arzamasovs, Maksims. "Static and dynamic correlation functions in one-dimensional bose liquids". Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5483/.

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This Thesis discusses approaches to calculating static and dynamic correlation functions in onedimensional gases of interacting bosons. The first part of the Thesis deals with the momentummomentum correlation function in the weakly interacting 1D Bose gas. In the regime of phase fluctuating quasicondensate this correlator is found to differ qualitatively from the form predicted by Bogoliubov theory of the true condensate in that correlations between any two values of momentum become finite. Linear hydrodynamics used to calculate the quasicondensate correlation function prove to be adequate. A classical field approximation is used to smoothly interpolate between the quasicondensate and strongly degenerate gas regimes. In the second part the focus is shifted to the dynamical structure factor and it is shown that hydrodynamics is generally inapplicable to calculating the dynamical correlators. The hydrodynamic treatment is enhanced using impurity theory and an exact model-dependent boundary is obtained for the region of applicability of hydrodynamics on the momentum-energy plane. Numerical estimates show that non-hydrodynamic behavior should be observable for the currently available values of experimental parameters.
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42

Faria, Rodrigo Augusto Dias. "Human skin segmentation using correlation rules on dynamic color clustering". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/45/45134/tde-01102018-101814/.

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Human skin is made of a stack of different layers, each of which reflects a portion of impinging light, after absorbing a certain amount of it by the pigments which lie in the layer. The main pigments responsible for skin color origins are melanin and hemoglobin. Skin segmentation plays an important role in a wide range of image processing and computer vision applications. In short, there are three major approaches for skin segmentation: rule-based, machine learning and hybrid. They differ in terms of accuracy and computational efficiency. Generally, machine learning and hybrid approaches outperform the rule-based methods but require a large and representative training dataset and, sometimes, costly classification time as well, which can be a deal breaker for real-time applications. In this work, we propose an improvement, in three distinct versions, of a novel method for rule-based skin segmentation that works in the YCbCr color space. Our motivation is based on the hypotheses that: (1) the original rule can be complemented and, (2) human skin pixels do not appear isolated, i.e. neighborhood operations are taken into consideration. The method is a combination of some correlation rules based on these hypotheses. Such rules evaluate the combinations of chrominance Cb, Cr values to identify the skin pixels depending on the shape and size of dynamically generated skin color clusters. The method is very efficient in terms of computational effort as well as robust in very complex images.
A pele humana é constituída de uma série de camadas distintas, cada uma das quais reflete uma porção de luz incidente, depois de absorver uma certa quantidade dela pelos pigmentos que se encontram na camada. Os principais pigmentos responsáveis pela origem da cor da pele são a melanina e a hemoglobina. A segmentação de pele desempenha um papel importante em uma ampla gama de aplicações em processamento de imagens e visão computacional. Em suma, existem três abordagens principais para segmentação de pele: baseadas em regras, aprendizado de máquina e híbridos. Elas diferem em termos de precisão e eficiência computacional. Geralmente, as abordagens com aprendizado de máquina e as híbridas superam os métodos baseados em regras, mas exigem um conjunto de dados de treinamento grande e representativo e, por vezes, também um tempo de classificação custoso, que pode ser um fator decisivo para aplicações em tempo real. Neste trabalho, propomos uma melhoria, em três versões distintas, de um novo método de segmentação de pele baseado em regras que funciona no espaço de cores YCbCr. Nossa motivação baseia-se nas hipóteses de que: (1) a regra original pode ser complementada e, (2) pixels de pele humana não aparecem isolados, ou seja, as operações de vizinhança são levadas em consideração. O método é uma combinação de algumas regras de correlação baseadas nessas hipóteses. Essas regras avaliam as combinações de valores de crominância Cb, Cr para identificar os pixels de pele, dependendo da forma e tamanho dos agrupamentos de cores de pele gerados dinamicamente. O método é muito eficiente em termos de esforço computacional, bem como robusto em imagens muito complexas.
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43

Olaya-Castro, Alexandra. "Dynamics of quantum correlations in multi-qubit-cavity systems". Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419329.

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44

Yonetani, Ryo. "Modeling Spatiotemporal Correlations between Video Saliency and Gaze Dynamics". 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180614.

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45

Geier, Kevin Thomas. "Probing Dynamics and Correlations in Cold-Atom Quantum Simulators". Doctoral thesis, Università degli studi di Trento, 2022. http://hdl.handle.net/11572/351120.

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Cold-atom quantum simulators offer unique possibilities to prepare, manipulate, and probe quantum many-body systems. However, despite the high level of control in modern experiments, not all observables of interest are easily accessible. This thesis aims at establishing protocols to measure currently elusive static and dynamic properties of quantum systems. The experimental feasibility of these schemes is illustrated by means of numerical simulations for relevant applications in many-body physics and quantum simulation. In particular, we introduce a general method for measuring dynamical correlations based on non-Hermitian linear response. This enables unbiased tests of the famous fluctuation-dissipation relation as a probe of thermalization in isolated quantum systems. Furthermore, we develop ancilla-based techniques for the measurement of currents and current correlations, permitting the characterization of strongly correlated quantum matter. Another application is geared towards revealing signatures of supersolidity in spin-orbit-coupled Bose gases by exciting the relevant Goldstone modes. Finally, we explore a scenario for quantum-simulating post-inflationary reheating dynamics by parametrically driving a Bose gas into the regime of universal far-from-equilibrium dynamics. The presented protocols also apply to other analog quantum simulation platforms and thus open up promising applications in the field of quantum science and technology.
I simulatori quantistici ad atomi freddi offrono possibilità uniche per preparare, manipolare e sondare sistemi quantistici a molti corpi. Tuttavia, nonostante l'alto livello di controllo raggiunto negli esperimenti moderni, non tutte le osservabili di interesse sono facilmente accessibili. Lo scopo di questa tesi è quello di stabilire protocolli per misurare delle proprietà statiche e dinamiche dei sistemi quantistici attualmente inaccessibili. La fattibilità sperimentale di questi schemi è illustrata mediante simulazioni numeriche per applicazioni rilevanti nella fisica a molti corpi e nella simulazione quantistica. In particolare, introduciamo un metodo generale per misurare le correlazioni dinamiche basato su una risposta lineare non hermitiana. Ciò consente test imparziali della famosa relazione fluttuazione-dissipazione come sonda di termalizzazione in sistemi quantistici isolati. Inoltre, sviluppiamo tecniche basate su ancilla per la misura di correnti e correlazioni di corrente, consentendo la caratterizzazione della materia quantistica fortemente correlata. Un'altra applicazione è orientata a rivelare l'impronta della supersolidità nei gas Bose con accoppiamento spin-orbita eccitando il corrispondente modo di Goldstone. Infine, esploriamo uno scenario per la simulazione quantistica della dinamica di riscaldamento post-inflazione modulando parametricamente un gas Bose e portandolo nel regime della dinamica universale lontana dall'equilibrio. I protocolli presentati si applicano anche ad altre piattaforme di simulazione quantistica analogica e aprono quindi applicazioni promettenti nel campo della scienza e della tecnologia quantistica.
Quantensimulatoren auf Basis ultrakalter Atome eröffnen einzigartige Möglichkeiten zur Präparation, Manipulation und Untersuchung von Quanten-Vielteilchen-Systemen. Trotz des hohen Maßes an Kontrolle in modernen Experimenten sind jedoch nicht alle interessanten Observablen auf einfache Weise zugänglich. Ziel dieser Arbeit ist es, Protokolle zur Messung aktuell nur schwer erfassbarer statischer und dynamischer Eigenschaften von Quantensystemen zu etablieren. Die experimentelle Realisierbarkeit dieser Verfahren wird durch numerische Simulationen anhand relevanter Anwendungen in der Vielteilchenphysik und Quantensimulation veranschaulicht. Insbesondere wird eine allgemeine Methode zur Messung dynamischer Korrelationen basierend auf der linearen Antwort auf nicht-hermitesche Störungen vorgestellt. Diese ermöglicht unabhängige Tests des berühmten Fluktuations-Dissipations-Theorems als Indikator der Thermalisierung isolierter Quantensysteme. Darüber hinaus werden Verfahren zur Messung von Strömen und Strom-Korrelationen mittels Kopplung an einen Hilfszustand entwickelt, welche die Charakterisierung stark korrelierter Quantenmaterie erlauben. Eine weitere Anwendung zielt auf die Enthüllung spezifischer Merkmale von Supersolidität in Spin-Bahn-gekoppelten Bose-Einstein-Kondensaten ab, indem die relevanten Goldstone-Moden angeregt werden. Schließlich wird ein Szenario zur Quantensimulation post-inflationärer Thermalisierungsdynamik durch die parametrische Anregung eines Bose-Gases in das Regime universeller Dynamik fern des Gleichgewichts erschlossen. Die dargestellten Protokolle lassen sich auch auf andere Plattformen für analoge Quantensimulation übertragen und eröffnen damit vielversprechende Anwendungen auf dem Gebiet der Quantentechnologie.
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46

Kasprzyk, Christina Ridley. "Practical applications of molecular dynamics techniques and time correlation function theories". [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001644.

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47

Fawcett, Philip Andrew. "An investigation on planar velocimetry by spatial cross correlation". Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/15731.

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48

Hopkins, Paul. "Static and dynamic correlations in some models of fluids". Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492547.

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In this thesis we investigate the equilibrium and dynamic correlations in a number of model fluids. We make extensive use of the bulk Ornstein-Zernike (OZ) framework for determining two-body correlation functions, and equilibrium density functional theory (DFT) for determining equilibrium one-body density profiles.
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49

Prieto, Judith Helena. "Correlations between dynamic motions and function in modular proteins /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3167828.

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50

Martins, Marcio Marques. "Influência de parâmetros moleculares em funções de correlação temporal na dinâmica de solvatação mecânica". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2004. http://hdl.handle.net/10183/6896.

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No presente trabalho descrevemos nossos resultados relativos à investigação da dinâmica de solvatação mecânica por meio de simulações por dinâmica molecular, respeitando o regime da resposta linear, em sistemas-modelo de argônio líquido com um soluto monoatômico ou diatômico dissolvido. Estudamos sistematicamente a influência dos parâmetros moleculares dos solutos (tamanho, polarizabilidade) e da densidade frente a vários modelos de solvatação. Funções de Correlação Temporal da Energia de Solvatação foram calculadas com relação à correlações de n-corpos (n = 2; 3) distinguindo interações repulsivas e atrativas para ambos os sistemas líquidos. Também obtivemos segundas derivadas temporais dessas funções referindo-se à parcelas translacionais, rotacionais e roto-translacionais na solução do diatômico. Encontramos que funções de correlação temporal coletivas podem ser razoavelmente bem aproximadas por correlações binárias a densidades baixas e, a densidades altas, correlações ternárias tornam-se mais importantes produzindo um descorrelacionamento mais rápido das funções coletivas devido a efeitos de cancelamento parciais. As funções de correlação para interações repulsivas e atrativas exibem comportamentos dinâmicos independentes do modelo de solvatação devido a fatores de escalonamento linear que afetam apenas as amplitudes das dessas funções de correlação temporal. Em geral, os sistemas com grau de liberdade rotacional apresentam tempos de correlação mais curtos para a dinâmica coletiva e tempos de correlação mais longos para as funções binárias e ternárias. Finalmente, esse estudo mostra que os sistemas contendo o diatômico relaxam-se predominantemente por mecanismos translacionais binários em modelos de solvatação envolvendo alterações apenas na polarizabilidade do soluto, e por mecanismos rotacionais atrativos binários em modelos envolvendo alterações no comprimento de ligação.
In the present work, we describe our results concerning our molecular dynamics investigation of the mechanical solvation dynamics within the linear response regime in model systems composed by liquid argon with a monoatomic or diatomic solute. The effect of molecular parameters (size, polarizability) and density has been elucidated for various solvation models. Time Correlation Functions for the solvation energy were calculated and separated into n-body (n = 2; 3) contributions distinguishing repulsive and attractive interactions in both liquid systems. In addition, we computed second time derivatives of these functions in order to describe translational, rotational, and roto-translational portions in the solutions containing the diatomics. We found that collective time correlation functions are well described by binary correlations at low liquid densities and, at high densities, ternary correlations become more important producing faster decaying collective time correlation functions due to partial cancellation effects. The repulsive and attractive time correlation functions exhibit a dynamic behavior that is independent on the solvation model due to linear scaling factors that only affect the absolute amplitudes of these functions. In general, the systems involving a rotational degree of freedom furnish smaller correlation times for the collective solvation dynamics, but stronger correlated two-body and three-body terms. Finally, this study shows that the solvation dynamics for the solution containing the diatomics relaxes predominatly by binary translational mechanisms when solvation models involving changes only in the polarizability parameter are considered. Binary attractive rotational mechanism become important in models with changes in the bond length.
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