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Staniscia, Fabio. "Out-of-equilibrium behavior of many-body Hamiltonian systems with different interaction ranges." Doctoral thesis, Università degli studi di Trieste, 2011. http://hdl.handle.net/10077/4972.
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2009/2010In this Thesis we describe the theoretical-computational study performed on the behavior of isolated systems, far from thermodynamic equilibrium. Analyzing models well-known in literature we follow a path bringing to the classification of different behaviors in function of the interaction range of the systems' particles. In the case of systems with long-range interaction we studied the "Quasi-Stationary states" (QSSs) which emerge at short times when the system evolves with Hamiltonian dynamics. Their interest is in the fact that in many physical systems, such as self-gravitating systems, plasmas and systems characterized by wave-particle interaction, QSSs are the only experimentally accessible regime. QSS are defined as stable solutions of the Vlasov equation and, as their duration diverges with the system size, for large systems' size they can be seen as the true equilibria. They do not follow the Boltzmann statistics, and it does not exists a general theory which describes them. Anyway it is possible to give an approximate description using Lynden-Bell theory. One part of the thesis is devoted to shed light on the characteristics of the phase diagram of the "Hamiltonian mean field" model (HMF), during the QSS, calculated with the Lynden-Bell theory. The results of our work allowed to confirm numerically the presence of a phase re-entrance. In the Thesis is present also a detailed description on the system's caloric curves and on the metastability. Still in this context we show an analysis of the equivalence of the statistical ensembles, confirmed in almost the totality of the phase diagram (except for a small region), although the presence of negative specific heat in the microcanonical ensemble, which in Boltzmannian systems implies the non-equivalence of statistical ensembles. This result allowed us to arrive to a surprising conclusion: the presence of negative specific heat in the canonical ensemble. Still in the context of long-range interacting systems we analyze the linear stability of the non-homogeneous QSSs with respect to the Vlasov equation. Since the study of QSS find an application in the Free-electron laser (FEL) and other light sources, which are characterized by wave-particle interaction, we analyze, in the last chapter, the experimental perspectives of our work in this context. The other class of systems we studied are short-range interacting systems. Here the behavior of the components of the system is strongly influenced by the neighbors, and if one takes a system in a disordered state (a zero magnetization state for magnetic systems), which relaxes towards an ordered equilibrium state, one sees that the ordering process first develops locally and then extends to the whole system forming domains of opposed magnetization which grow in size. This process is called "coarsening". Our work in this field consisted in investigating numerically the laws of scale, and in the Thesis we characterize the temporal dependence of the domain sizes for different interaction ranges and we show a comparison between Hamiltonian and Langevin dynamics. This work inserts in the open debate on the equivalence of different dynamics where we found that, at least for times not too large, the two dynamics give different scaling laws.
In questa Tesi è stato fatto uno studio di natura teorico-computazionale sul comportamento dei sistemi isolati lontani dall'equilibrio termodinamico. Analizzando modelli noti in letteratura è stato seguito un percorso che ha portato alla classificazione di differenti comportamenti in funzione del range di interazione delle particelle del sistema. Nel caso di sistemi con interazione a lungo raggio sono stati studiati gli "stati quasi-stazionari" (QSS) che emergono a tempi brevi quando il sistema evolve con dinamica hamiltoniana. Il loro interesse risiede nel fatto che in molti sistemi fisici, come i sistemi auto-gravitanti, plasmi e sistemi caratterizzati da interazione onda-particella, i QSS risultano essere gli unici regimi accessibili sperimentalmente. I QSS sono definiti come soluzioni stabili dell'equazione di Vlasov, e visto che la loro durata diverge con la taglia del sistema, per sistemi di grandi dimensioni possono essere visti come i veri stati di equilibrio. Questi non seguono la statistica di Bolzmann, e non esiste una teoria generale che li descriva. E' tuttavia possibile fare una descrizione approssimata utilizzando la teoria di Lynden-Bell. Una parte della tesi è dedicata alla comprensione delle caratteristiche del diagramma di fase del modello "Hamiltonian mean field" (HMF) durante il QSS, calcolato con la teoria di Lynden-Bell. Il risultato del nostro lavoro ha permesso di confermare numericamente la presenza di fasi rientrati. E' inoltre presente un'analisi dettagliata sulle curve caloriche del sistema e sulla metastabilità. Sempre in questo contesto è stata fatto uno studio sull'equivalenza degli ensemble statistici, confermata nella quasi totalità del diagramma di fase (tranne in una piccola regione), nonostante la presenza di calore specifico negativo nell'insieme microcanonico, che in sistemi Boltzmanniani è sinonimo di non-equivalenza degli ensemble statistici. Questo risultato ci ha permesso di arrivare ad una sorprendente conclusione: la presenza di calore specifico negativo nell'insieme canonico. Sempre nel contesto dei sistemi con interazione a lungo range, è stata analizzata la stabilità lineare rispetto all'equazione di Vlasov degli stati quasi-stazionari non-omogenei. Poiché lo studio dei QSS trova applicazione nel Free-electron laser (FEL) e in altre sorgenti di luce, caratterizzate dall'interazione onda-particella, abbiamo analizzato anche le prospettive sperimentali del nostro lavoro in questo contesto. L'altra classe di sistemi che è stata studiata sono i sistemi con interazione a corto raggio. Qui il comportamento dei componenti del sistema è fortemente influenzato dai vicini, e se si prende un sistema in uno stato disordinato (a magnetizzazione nulla nei sistemi magnetici) che rilassa verso l'equilibrio ordinato, si vede che il processo di ordinamento si sviluppa prima localmente e poi si estende a tutto il sistema formando dei domini di magnetizzazione opposta che crescono in taglia. Questo processo si chiama "coarsening". Il nostro lavoro in questo contesto è consistito in una investigazione numerica delle leggi di scala, e nella tesi è stata caratterizzata la dipendenza temporale della taglia dei domini per differenti range di interazione ed è stato fatto un confronto fra dinamica hamiltoniana e dinamica di Langevin. Questi risultati si inseriscono nel dibattito aperto sull'equivalenza di differenti dinamiche, e si è mostrato che, almeno per tempi non troppo grandi, le due dinamiche portano a leggi di scala differenti.
XXIII Ciclo
1982
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Benitez, Federico. "Non Perturbative Renormalization Group : from equilibrium to non-equilibrium." Paris 6, 2013. http://www.theses.fr/2013PA066009.
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Un grand nombre de problèmes ouverts parmi les plus importants en mécanique statistique sont liés aux systèmes hors de l'équilibre thermique. Dans ce travail, nous utilisons des méthodes de théorie de champs pour étudier certains de ces systèmes. Pour ce faire, nous introduisons une représentation de type théorie de champs pour les systèmes d'intérêt, ainsi que le formalisme spécifique utilisé partout dans ce travail, le groupe de renormalisation non perturbatif (NPRG). Ce formalisme a émergé dans les dernières années comme un moyen très efficace pour étudier les systèmes fortement corrélés, et il a été appliqué avec succès à certains problèmes dans et hors de l'équilibre thermique. Avant de traiter les systèmes qui nous intéressent, nous développons de nouveaux outils et méthodes dans le cadre du NPRG, et nous les testons dans le cas relativement simple d'une théorie de champ scalaire, appartenant à la classe d'universalité d'Ising. Celui ci nous permet d'obtenir la fonction d'échelle du modèle d'Ising en d = 3, sans avoir à fixer aucun paramètre libre. En outre, afin de faire face de manière efficace à la physique des systèmes hors d'équilibre, nous étudions en détail certains aspects formels de leur passage à une représentation de type théorie des champs, ainsi que les équivalences entre les différentes voies possibles pour mettre en oeuvre ce passage. Après ces préliminaires, nous nous concentrons sur les transitions de phase hors d'équilibre dans des systèmes de réaction-diffusion, et en particulier dans la sous-classe connue sous le nom de marches aléatoires avec branchement et annihilation (BARW). Parmi d'autres résultats, nous utilisons le NPRG pour trouver une solution exacte pour un des cas les plus simples de système de réaction-diffusion, connu comme l'annihilation pure. Avec cette solution, nous analysons certaines propriétés des systèmes BARW à bas taux de branchement, en utilisant un développement autour de l'annihilation pure. Ce développement perturbatif, qui est réalisé autour d'un modèle non trivial, nous permet de trouver des résultats exacts pour certaines des plus importantes classes d'universalité de ces systèmesMany of the most important open problems in statistical mechanics are related with systems out of thermal equilibrium. In this work we use field theory methods to study some of these systems. To do so, we first introduce a field theory representation for the systems of interest, as well as the specific formalism to be used throughout, the so-called non perturbative renormalization group (NPRG). This formalism has emerged in the last years as a very efficient way to deal with strongly correlated systems, and has been applied with success to problems both in and out of equilibrium. Before treating the actual systems of interest, we develop some new tools and methods within the NPRG context, and test them in a simple scalar field theory, belonging to the Ising universality class. We are able to obtain results for the momentum-dependent scaling function of the d=3 Ising model, without having to fix any free parameter. Also, in order to tackle in an efficient way the physics of out of equilibrium systems, we study in detail some formal aspects of their passage to a field theory representation, as well as the equivalences between different possible ways to perform this passage. After these preliminaries, we concentrate in out of equilibrium active-to-absorbing phase transitions in reaction-diffusion systems, and in particular in the subclass known as branching and annihilating random walks (BARW). Among other results, we use the NPRG to find an exact solution to any vertex in a simple system, known as pure annihilation. With this, we analyze some properties of BARW at low branching rates, by means of an expansion in the branching rate around pure annihilation. This perturbative expansion, which is performed around a nontrivial model, allows us to find some striking exact results for some of the most important universality classes in these systems
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Pop, Cristina-Maria. "Non-equilibrium relaxation." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-151719.
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Jizba, Petr. "Equilibrium and non-equilibrium quantum field theory." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624406.
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Degawa, Masashi. "Equilibrium and non-equilibrium properties of finite-volume crystallites." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3377.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Solbraa, Even. "Equilibrium and Non-Equilibrium Thermodynamics of Natural Gas Processing." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-96.
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The objective of this work has been to study equilibrium and non equilibrium situations during high pressure gas processing operations with emphasis on utilization of the high reservoir pressure. The well stream pressures of some of the condensate and gas fields in the North Sea are well above 200 bar. Currently the gas is expanded to a specified processing condition, typically 40-70 bar, before it is recompressed to the transportation conditions. It would be a considerable environmental and economic advantage to be able to process the natural gas at the well stream pressure. Knowledge of thermodynamic- and kinetic properties of natural gas systems at high pressures is needed to be able to design new high pressure process equipment.
Nowadays, reactive absorption into a methyldiethanolamine (MDEA)solution in a packed bed is a frequently used method to perform acid gas treating. The carbon dioxide removal process on the Sleipner field in the North Sea uses an aqueous MDEA solution and the operation pressure is about 100 bar. The planed carbon dioxide removal process for the Snøhvit field in the Barents Sea is the use of an activated MDEA solution.
The aim of this work has been to study high-pressure effects related to the removal of carbon dioxide from natural gas. Both modelling and experimental work on high-pressure non-equilibrium situations in gas processing operations have been done.
Few experimental measurements of mass transfer in high pressure fluid systems have been published. In this work a wetted wall column that can operate at pressures up to 200 bar was designed and constructed. The wetted wall column is a pipe made of stainless steel where the liquid is distributed as a thin liquid film on the inner pipewall while the gas flows co- or concurrent in the centre of the pipe. The experiments can be carried out with a well-defined interphase area and with relatively simple fluid mechanics. In this way we are able to isolate the effects we want to study in a simple and effective way.
Experiments where carbon dioxide was absorbed into water and MDEA solutions were performed at pressures up to 150 bar and at temperatures 25 and 40°C. Nitrogen was used as an inert gas in all experiments.
A general non-equilibrium simulation program (NeqSim) has been developed. The simulation program was implemented in the object-oriented programming language Java. Effort was taken to find an optimal object-oriented design. Despite the increasing popularity of object-oriented programming languages such as Java and C++, few publications have discussed how to implement thermodynamic and fluid mechanic models. A design for implementation of thermodynamic, mass transfer and fluid mechanic calculations in an object-oriented framework is presented in this work.
NeqSim is based on rigorous thermodynamic and fluid mechanic models. Parameter fitting routines are implemented in the simulation tool and thermodynamic-, mass transfer- and fluid mechanic models were fitted to public available experimental data. Two electrolyte equations of state were developed and implemented in the computer code. The electrolyte equations of state were used to model the thermodynamic properties of the fluid systems considered in this work (non-electrolyte, electrolyte and weak-electrolyte systems).
The first electrolyte equation of state (electrolyte ScRK-EOS) was based on a model previously developed by Furst and Renon (1993). The molecular part of the equation was based on a cubic equation of state (Scwarzentruber et.al. (1989)’s modification of the Redlich-Kwong EOS) with the Huron-Vidal mixing rule. Three ionic terms were added to this equation – a short-range ionic term, a long-range ionic term (MSA) and a Born term. The thermodynamic model has the advantage that it reduces to a standard cubic equation of state if no ions are present in the solution, and that public available interaction parameters used in the Huron-Vidal mixing rule could be utilized. The originality of this electrolyte equation of state is the use of the Huron-Vidal mixing rule and the addition of a Born term. Compared to electrolyte models based on equations for the gibbs excess energy, the electrolyte equation of state has the advantage that the extrapolation to higher pressures and solubility calculations of supercritical components is less cumbersome. The electrolyte equation of state was able to correlate and predict equilibrium properties of CO2-MDEA-water solutions with a good precision. It was also able to correlate high pressure data of systems of methane-CO2-MDEA and water.
The second thermodynamic model (electrolyte CPA-EOS) evaluated in this work is a model where the molecular interactions are modelled with the CPA (cubic plus association) equation of state (Kontogeorgios et.al., 1999) with a classical one-parameter Van der Walls mixing rule. This model has the advantage that few binary interaction parameters have to be used (even for non-ideal solutions), and that its extrapolation capability to higher pressures is expected to be good. In the CPA model the same ionic terms are used as in the electrolyte ScRK-EOS.
A general non-equilibrium two-fluid model was implemented in the simulation program developed in this work. The heat- and mass-transfer calculations were done using an advanced multicomponent mass transfer model based on non-equilibrium thermodynamics. The mass transfer model is flexible and able to simulate many types of non-equilibrium processes we find in the petroleum industry. A model for reactive mass transfer using enhancement factors was implemented for the calculation of mass transfer of CO2 into amine solutions. The mass transfer model was fitted to the available mass transfer data found in the open literature.
The simulation program was used to analyse and perform parameter fitting to the high pressure experimental data obtained during this work. The mathematical models used in NeqSim were capable of representing the experimental data of this work with a good precision. From the experimental and modelling work done, we could conclude that the mass transfer model regressed to pure low-pressure data also was able to represent the high-pressure mass transfer data with an acceptable precision. Thus the extrapolation capability of the model to high pressures was good.
For a given partial pressure of CO2 in the natural gas, calculations show a decreased CO2 capturing capacity of aqueous MDEA solutions at increased natural gas system pressure. A reduction up to 40% (at 200 bar) compared to low pressure capacity is estimated. The pressure effects can be modelled correctly by using suitable thermodynamic models for the liquid and gas. In a practical situation, the partial pressure of CO2 in the natural gas will be proportional to the total pressure. In these situations, it is shown that the CO2 capturing capacity of the MDEA solution will be increased at rising total pressures up to 200 bar. However, the increased capacity is not as large as we would expect from the higher CO2 partial pressure in the gas.
The reaction kinetics of CO2 with MDEA is shown to be relatively unaffected by the total pressure when nitrogen is used as inert gas. It is however important that the effects of thermodynamic and kinetic non- ideality in the gas and liquid phase are modelled in a consistent way. Using the simulation program NeqSim – some selected high-pressure non-equilibrium processes (e.g. absorption, pipe flow) have been studied. It is demonstrated that the model is capable of simulating equilibrium- and non-equilibrium processes important to the process- and petroleum industry.
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Willis, Gary. "On topics in equilibrium and non-equilibrium statistical physics." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/28952.
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This thesis divides very naturally into three chapters, reflecting the three separate areas I have worked in throughout my PhD studies. During my PhD, I published two papers, one relating to the work in the first chapter, and one to that of the second. At the time of submission, the project which the third chapter relates to was still ongoing, with plans for a future publication. The first chapter discusses work done on the real space renormalisation group (RG) for Ising and Potts models in 2 dimensions. Taking inspiration from Hasenbusch's work, a new framework for carrying out the RG is developed, its computational implementation discussed in some detail, as well as the results for a variety of systems and the implications of these results. The numerical scaling of the procedure and the consequences of this for future work are also covered. The results documented in chapter two are purely theoretical and presented in closed form. The research conducted is to do with properties of free interfaces. The second chapter is by and large critical of previous assumptions which have been made about the so-called wave vector dependent, in order to attempt to experimentally measure it and use these measurements to make further predictions. Using some simple toy models, many of these assumptions are shown to be false. In a sense, the goal of the research presented in the chapter two, is not to motivate further research, but to dissuade research in a direction we consider to be misguided, due to the faulty assumptions it is based on. The third chapter covers a small subset of a project concerned with studying correlations within the so-called Abelian Manna Model. The majority of the project involves (computational) Monte Carlo simulations of the dynamics of such systems, but as these results are not ready to present at the time of writing, the chapter is mainly concerned with some analytical results which were derived in order to validate our models for small systems, explain certain quirky phenomena arising from our simulations, and help quantify errors. Finally, there is an appendix which expands upon various topics from the first two chapters.
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Harris, Rosemary J. "Disorder in non-equilibrium models." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408687.
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Depken, Martin. "Models of non-equilibrium systems." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398044.
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Hornett, Samuel Martyn. "Non-equilibrium phenomena in graphene." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/13022.
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Graphene has displayed much promise as an electrical conductor and as a optical material. To date there is a large body of literature dedicated to the equilibrium properties of graphene. In this thesis the properties of graphene out of equilibrium are probed. Through combined optical and transport measurements the behaviour of hot electrons are probed at temperatures over five orders of magnitude from 50mK to 2000K. This wide range of temperatures allows access to the behaviour of quantum corrections at the lowest temperatures to the highest energy phonon modes. From ultrafast femtosecond laser pulses to steady state heating from an electric field the cooling of hot electron populations through coupling to various phonon modes in the graphene and the substrate are explored. Additionally the effect of an electric field on the weak localisation correction to the conductivity was separated from heating effects using applied magnetic fields combined with careful modelling of the heat transport properties of the graphene. Finally the desorption dynamics of oxygen bound to the surface are shown using a combination of transport and two pulse correlation technique using an ultrafast laser. Surprisingly the cooling of hot carriers in graphene at low energies shows substrate surface phonons as an important cooling mechanism, highlighting the importance of substrate choice in future graphene devices. In contrast at the very highest energy scales accessed only by photoexcitation the cooling is shown not to be influenced by the presence of a substrate, but out-of-plane phonon modes increase cooling of the hot optical phonons.
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Johnson, Tomi Harry. "Non-equilibrium strongly-correlated dynamics." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:55d438cc-d9a1-4898-ac05-49299bad6806.
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We study non-equilibrium and strongly-correlated dynamics in two contexts. We begin by analysing quantum many-body systems out of equilibrium through the lens of cold atomic impurities in Bose gases. Such highly-imbalanced mixtures provide a controlled arena for the study of interactions, dissipation, decoherence and transport in a many-body quantum environment. Specifically we investigate the oscillatory dynamics of a trapped and initially highly-localised impurity interacting with a weakly-interacting trapped quasi low-dimensional Bose gas. This relates to and goes beyond a recent experiment by the Inguscio group in Florence. We witness a delicate interplay between the self-trapping of the impurity and the inhomogeneity of the Bose gas, and describe the dissipation of the energy of the impurity through phononic excitations of the Bose gas. We then study the transport of a driven, periodically-trapped impurity through a quasi one-dimensional Bose gas. We show that placing the weakly-interacting Bose gas in a separate periodic potential leads to a phononic excitation spectrum that closely mimics those in solid state systems. As a result we show that the impurity-Bose gas system exhibits phonon-induced resonances in the impurity current that were predicted to occur in solids decades ago but never clearly observed. Following this, allowing the bosons to interact strongly, we predict the effect of different strongly-correlated phases of the Bose gas on the motion of the impurity. We show that, by observing the impurity, properties of the excitation spectrum of the Bose gas, e.g., gap and bandwidth, may be inferred along with the filling of the bosonic lattice. In other words the impurity acts as a probe of its environment. To describe the dynamics of such a strongly-correlated system we use the powerful and near-exact time-evolving block decimation (TEBD) method, which we describe in detail. The second part of this thesis then analyses, for the first time, the performance of this method when applied to simulate non-equilibrium classical stochastic processes. We study its efficacy for a well-understood model of transport, the totally-asymmetric exclusion process, and find it to be accurate. Next, motivated by the inefficiency of sampling-based numerical methods for high variance observables we adapt and apply TEBD to simulate a path-dependent observable whose variance increases exponentially with system size. Specifically we calculate the expected value of the exponential of the work done by a varying magnetic field on a one-dimensional Ising model undergoing Glauber dynamics. We confirm using Jarzynski's equality that the TEBD method remains accurate and efficient. Therefore TEBD and related methods complement and challenge the usual Monte Carlo-based simulators of non-equilibrium stochastic processes.
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Willmer, D. "Non-equilibrium polymeric complex fluids." Thesis, Nottingham Trent University, 2011. http://irep.ntu.ac.uk/id/eprint/247/.
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Complex fluids are commercially- and industrially-important materials which exhibit ordering on scales much larger than atomic. Their usage is typically in non-equilibrium conditions, however traditional methods for measuring rheology are not appropriate for measuring samples with gradients present, such as temperature and concentration. In this work a safe and easy to use optical tweezer (OT) apparatus has been developed in order to facilitate the investigation of various systems during dilution or drying. In contrast to other OT setups, this equipment is safe to use without laser goggles or interlocked rooms, yet still allows full access to the microscope. Proof-of-concept experiments are performed on aqueous poly (ethylene oxide) (PEO) solutions to demonstrate the changes in viscosity and concentration over time, and the OT is then used in a rheological investigation into a commercially-relevant wormlike micelle (WLM) system, in conjunction with Diffusing Wave Spectroscopy (DWS) and traditional bulk rheology. It is shown for the first time that equimolar (eM) SDS:CAPB WLM samples can be considered ‘model’ systems, and form close approximations of Maxwellian systems on the addition of extra salt or surfactant above 0.1eM. The effect of an uncharged polymer (PEO 4M MW) on this WLM network structure was subsequently investigated; its effects are consistent with current theories of polymer-surfactant interactions. The effect of a conditioning polyelectrolyte on the network structure was also studied; its effect was highly dependent on surfactant and electrolyte concentration, but hinted at the previously unreported behaviour of a polyelectrolyte initiating micellar branching. A precursor investigation into evaporation of sessile droplets of aqueous PEO solutions is presented last, reporting a previously unseen droplet evaporation regime in which the solid deposits grow to nearly twice their starting height. This research concludes that the growth phenomena is due to the unusual solvation mechanism of PEO, and a predictive theory is presented in support of this.
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Hader, J., I. Kilen, S. W. Koch, and J. V. Moloney. "Non-equilibrium effects in VECSELs." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/625513.
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A systematic study of microscopic many-body dynamics is used to analyze a strategy for how to generate ultrashort mode locked pulses in the vertical external-cavity surface-emitting lasers with a saturable absorber mirror. The field propagation is simulated using Maxwell's equations and is coupled to the polarization from the quantum wells using the semiconductor Bloch equations. Simulations on the level of second Born-Markov are used to fit coefficients for microscopic higher order correlation effects such as dephasing of the polarization, carrier-carrier scattering and carrier relaxation. We numerically examine recent published experimental results on mode locked pulses, as well as the self phase modulation in the gain chip and SESAM.
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Harada, Takahiro. "Energetics of non-equilibrium fluctuations." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/144602.
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Kyoto University (京都大学)0048
新制・課程博士
博士(理学)
甲第11823号
理博第2944号
新制||理||1441(附属図書館)
23583
UT51-2005-K489
京都大学大学院理学研究科物理学･宇宙物理学専攻
(主査)教授 吉川 研一, 教授 小貫 明, 教授 太田 隆夫
学位規則第4条第1項該当
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Antunes, Nuno Dias. "Equilibrium and non-equilibrium aspects of early universe phase transitions." Thesis, University of Sussex, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264553.
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Barkhudarov, Evgeny. "Renormalization group analysis of equilibrium and non-equilibrium charged systems." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11049.
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In this thesis we investigate properties of equilibrium and non-equilibrium systems by means of renormalization group (RG) analysis. In the study of the d-dimensional Coulomb gas we have formulated a continuum model from the underlying hyper-cubic lattice and employed the irreducible differential formulation of the Wilson RG.We have identified a Thouless-Kosterletz transition in d=2 and found no non-trivial fixed points for d>2. As an example of a non-equilibrium system, we have investigated properties of quasi-neutral plasmas which are governed by stochastic magnetohydrodynamic (MHD) equations. The present method is based upon the Martin-Siggia-Rose field-theory formulation of stochastic dynamics. We develop a diagrammatic representation for the theory and carry out a momentum-shell RG of Wilson-Kadanoff type. An infinite set of diagrams is identified which are marginal in the RG sense. We have shown, in accordance with previous literature, that the same problem arises for the randomly-forced Navier-Stokes equation. The problem of marginal variables can be suppressed by working near equilibrium, where stochastic forcing represents thermal fluctuations. In a similar manner we have considered regimes when MHD equations are subject either to kinetic or magnetic forcing only. In such models the macroscopic limit can be taken such that all marginal terms are irrelevant and the dynamics is governed by linear equations. Furthermore, non-trivial fixed points are identified in such regimes and limiting values of either kinematic viscosity or magnetic diffusivity are derived. A consistent description of MHD dynamics far from equilibrium is still absent. We highlight some of the aspects of the functional integral formulation with regards to the symmetries of the system and propose possible ways in which the system can be studied non-pertubatively.
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Voldsund, Mari. "Modelling distillation with non-equilibrium thermodynamics." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-6864.
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Rossokhaty, Oleksandr. "Non-equilibrium transport in electron solids." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/60199.
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Electron-electron interactions inside of two dimensional electron gases (2DEG) in out-of-plane magnetic field and at very low temperatures under certain conditions can lead to electron localization in Wigner crystals or even more complex periodic structures. These states are usually referred to as electron solid phases and result in Reentrant Integer Quantum Hall Effect (RIQHE) in transport measurements. However, their microscopic description remains unclear, as insulating phases with different microscopic structure demonstrate indistinguishable macroscopic transport properties. In this work the transport of the electron solids is investigated away from equilibrium conditions. This approach allows to break an insulating state by application of significant current bias to the 2DEG. As bias current increases, longitudinal and Hall resistivities measured for these states show multiple sharp breakdown transitions. Whereas the high bias breakdown of fractional quantum Hall states is consistent with simple heating, the nature of RIQH breakdown remains to be a subject of a considerable debate. A comparison of RIQH breakdown characteristics at multiple voltage probes indicates that these signatures can be ascribed to a phase boundary between broken-down and unbroken regions, spreading chirally from source and drain contacts as a function of bias current and passing voltage probes one by one. It is shown, that the chiral sense of the spreading is not set by the chirality of the edge state itself, instead depending on electron- or hole-like character of the RIQH state. Although at high current bias the electron temperature is unmeasurable with standard techniques, the data shows that electron solid states appear to stay temperature sensitive even after the RIQH effect is destroyed. A comparison of temperature dependence and the spatial distribution of the Hall potential along the edge provides an evidence, that the bulk 2DEG remains insulating up to surprisingly high biases. Finally a metastable stripe phase around $\nu=9/2$ is investigated under non-equilibrium conditions in the sample with electron density, which is close to the stripe reorientation critical point. The anisotropy of non-equilibrium stripe phase under high current biases shows a strong dependence of the natural orientation of stripes on exact filling factor.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Wiener, Alexander David. "Non-equilibrium current fluctuations in graphene." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/47737.
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We analyze experimental evidence of transport through evanescent waves in graphene, reconciling existing experimental data with theory. We propose novel experimental geometries that provide even more compelling evidence of evanescent waves. We investigate the shot noise generated by evanescent modes in graphene for several experimental setups. For two impurity-free graphene strips kept at the Dirac point by gate potentials, separated by a long highly doped region, we find that the Fano factor takes the universal value F=1/4. For a large superlattice consisting of many strips gated to the Dirac point, interspersed among doped regions, we find F=1/(8ln2). These results differ from the value F=1/3 predicted for a disordered metal, providing an unambiguous experimental signature of evanescent mode transport in graphene. For a graphene nano-ribbon transistor geometry, we explain that the experimentally observed anomalous voltage scale of the shot noise can arise from doping by the contacts to the electrical circuit. These observations provide strong evidence of evanescent mode transport in graphene.
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Ke, Youqi. "Theory of non-equilibrium vertex correction." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=96987.
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For realistic nanostructures, there are inevitably some degree ofdisorder such as impurity atoms, imperfect lattices, surfaceroughness, etc.. For situations where disorder locate randomly inthe nanostructure, any calculated quantum transport results shouldbe averaged over disorder distributions. A brute force approach isto generate many disorder configurations, calculate each of them,and then average the results. For atomistic first principlesmodeling, such a brute force averaging is computationallyprohibitive - if not impossible, to perform. It is therefore veryimportant and useful to develop a theoretical framework where thedisorder averaging is done analytically before atomic firstprinciples analysis is carried out.In this thesis, we have developed such a first principlesnon-equilibrium quantum transport theory and its associated modelingsoftware for predicting disorder scattering in nano-electronicdevices. Our theoretical formalism is based on carrying out densityfunctional theory (DFT) within the Keldysh non-equilibrium Green'sfunction (NEGF) framework, and a non-equilibrium vertex correction(NVC) theory for handling disorder configurational average at thenon-equilibrium density matrix level. In our theory, we use thecoherent potential approximation to calculate disorder averaging ofthe device Hamiltonian and one particle Green's functions, and useNVC to calculate correlated multiple impurity scattering at thenon-equilibrium density matrix level. After the NEGF-DFT-NVCself-consistent calculation is converged, we calculate thetransmission coefficients by a second, unavoidable, vertexcorrection. The NEGF-DFT-NVC theory allows us to predictnon-equilibrium quantum transport properties of nanoelectronicdevices with atomistic disorder from first principles without anyphenomenological parameters. The theory and implementation detailsare presented.We have applied the NEGF-DFT-NVC method to investigate severalimportant problems associated with disorder scattering innano-electronic device systems. These include interface roughnessscattering in Fe/vacuum/Fe magnetic tunnel junctions; the diffusivescattering of carriers due to oxygen vacancies in Fe/MgO/Fe magnetictunnel junctions; the surface roughness scattering that enhancesresistivity of copper interconnect wires; and effects of barrierlayer coating for Cu interconnects. Our investigations reveal veryimportant role played by the atomic level defects and impurities toboth equilibrium and nonequilibrium quantum transport properties,and results compare favorably with the corresponding experimentaldata.Dans le cas de nanostructures concrètes, un certain degré de désordre apparaît inévitable tel que la présence d'impuretés, de structures cristallines imparfaites, de surfaces rugueuses, etc. Dans les situations où le désordre se matérialise aléatoirement dans la nanostructure, tout calcul de transport quantique devrait être réalisé en tant que moyenne sur plusieurs distributions désordonnées. Une approche par force brute consiste à générer plusieurs configurations désordonnées, calculer les propriétés d'intérêt pour chacune d'entre elles, et ensuite effectuer la moyenne des résultats. Dans le cas de la modélisation atomique à partir des principes premiers, une telle moyenne par force brute est prohibitive en terme de temps de calcul - sinon impossible. Il est ainsi très important et utile de développer un cadre théorique où la moyenne de désordre est faite analytiquement avant que l'analyse par les principes premiers ne soit effectuée. Dans cette thèse, nous avons développé une telle théorie de transport quantique hors équilibre à partir des principes premiers et le logiciel de modélisation associé pour la prédiction de la diffusion par désordre dans des dispositifs nanoélectroniques. Notre formalisme théorique est basé sur l'utilisation de la théorie de la fonctionnelle de densité (DFT) dans le cadre de la fonction de Green hors équilibre de Keldysh(NEGF), et sur l'emploi d'une correction de sommet hors équilibre (NVC) pour le traitement des moyennes configurationnelles de désordre au niveau de la matrice de densité hors équilibre. Dans notre théorie, nous utilisons l'approximation du potentiel cohérent afin de calculer les moyennes de désordre de l'Hamiltonien du dispositif et les fonctions de Green à une particule, et nous utilisons la NVC pour calculer la diffusion par impuretés multiples corrélée au niveau de la matrice de densité hors équilibre. Après que le calcul auto-cohérent NEGF-DFT-NVC ait convergé, nous calculons les coefficients de transmission par le biais d'une seconde correction de sommet inévitable. La théorie NEGF-DFT-NVC nous permet de prédire les propriétés de transport quantique hors équilibre de dispositifs nanoélectroniques avec désordre au niveau atomique à partir des principes premiers sans aucun paramètre phénoménologique. La théorie et les détails d'implémentation sont présentés dans ce travail. Nous avons appliqué la méthode NEGF-DFT-NVC afin d'examiner plusieurs problèmes importants associés à la diffusion par désordre dans des systèmes de dispositif nanoélectronique. Cela inclut la diffusion par rugosité de surface dans des jonctions tunnel magnétiques Fe/vide/Fe; la diffusion due à des lacunes d'oxygène dans des jonctions tunnel magnétiques Fe/MgO/Fe; la diffusion par rugosité de surface qui décuple la resistivité de fils deconnexion en cuivre; et les effets des revêtements couche barrière pour des connexionsen Cu. Notre étude révèle le rôle très important joué par les défauts de niveau atomique et les impuretés vis-à-vis des propriétés de transport quantique à la fois en équilibre et hors équilibre, et les résultats se comparent favorablement aux données expérimentales correspondantes.
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Evans, Allan Kenneth. "Foundations of non-equilibrium statistical mechanics." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389831.
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Head, David Andrew. "Topics in non-equilibrium systems theory." Thesis, Brunel University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246169.
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Barroy, Pierre ReneÌ Jean. "Electron kinetics in non-equilibrium plasmas." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272394.
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Caio, Marcello Davide. "Non-equilibrium dynamics of Chern insulators." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/nonequilibrium-dynamics-of-chern-insulators(32b36d8e-f927-4224-999c-3170f749f213).html.
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Topological states of matter exhibit a wealth of novel properties including the exact quantisation of macroscopic observables and the presence of edge states. In this thesis, we study the non-equilibrium dynamics of a class of topological phases, known as Chern insulators. By focusing on the Haldane model, we study quenches between the topological and non-topological phases, and the dynamics induced on physical observables. A notable feature is that the Chern number, calculated for an infinite system, is unchanged under the dynamics following such a quench. However, in finite-size geometries, the initial and final Hamiltonians are distinguished by the presence or absence of edge states. We study the edge excitations and describe their impact on the dynamics of the edge currents and the magnetisation. We show that, following a quantum quench, the edge currents relax towards new steady-state values, and that there is light-cone spreading of the currents into the interior of the sample. The late-time behaviour of the edge currents, after multiple traversals of the sample, is captured by a Generalised Gibbs Ensemble. We further provide an analysis of the Hall response following a quantum quench in an isolated system, with explicit results for the Haldane model. We show that the Hall conductance is no longer related to the Chern number in the post-quench state, in contrast to the equilibrium case. We also discuss the effects of generic open boundary conditions and confinement potentials. Finally, we discuss the impact of disorder on the phases of the Haldane model, both in and out of equilibrium. We conclude with a discussion of ongoing work on the non-equilibrium dynamics of the entanglement spectrum of the Haldane model, and with prospects for further research. The results presented in Chapters 2 and 3 are published in Refs [1, 2]. The results in Chapter 4 are currently in preparation for publication [3].
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Chou, Yen-Liang. "Relaxation phenomena during non-equilibrium growth." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/28574.
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The surface width, a global quantity that depends on time, is used to characterize the temporal evolution of growing surfaces. One of the most successful concepts for describing the property of the surface width is the famous Family-Vicsek scaling relation. We discuss an extended scaling relation that yields a complete description for various growth models.
For two linear Langevin equations, namely the Edwards-Wilkinson equation and the Mullins-Herring equation, we furthermore study analytically the behavior of global quantities related to the surface width or to a quantity which is conjugated to the diffusion constant. The global quantities depend in a non-trivial way on two different times. We discuss the dynamical scaling forms of global correlation and response functions.
For global functions related to the surface width, we show that the scaling behavior of the response can depend on how the system is perturbed. Different dynamic regimes, characterized by a power-law or by an exponential relaxation, are identified, and a dynamic phase diagram is constructed. We discuss global fluctuation-dissipation ratios and how to use them for the characterization of non-equilibrium growth processes. We also numerically study the same two-time quantities for the non-linear Kardar-Parisi-Zhang equation.
For global functions related to the quantity which is conjugated to the diffusion constant of the linear Langevin equations, we show that the integrated response is proportional to the correlation in the linear response regime. In the aging regime, the autocorrelation and autoresponse exponents are identical and the aging exponent for the response is equal to the aging exponent for the correlation. We investigate the non-equilibrium fluctuation-dissipation theorem for non-equilibrium states based on this quantity. In the non-linear response regime a certain dissipation-fluctuation ratio approximates unity for small waiting times but approaches the ratio of perturbed and unperturbed diffusion constants for larger waiting times.Ph. D.
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Compton, Ryan Edward. "Nonlinear Optics in Non-Equilibrium Microplasmas." Diss., Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/123146.
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ChemistryPh.D.
This dissertation details the nature of subnanosecond laser-induced microplasma dynamics, particularly concerning the evolution of the electron temperature and concentration. Central to this development is the advent of a femtosecond four-wave mixing (FWM) spectroscopic method. FWM (in the form of coherent anti-Stokes Raman scattering (CARS)) measurements are performed on the fundamental oxygen vibrational transition. An analytical expression is provided that accounts for the resonant and nonresonant contributions to the CARS signal generated from the interaction of broadband pump and Stokes pulses. The inherent phase mismatch is also accounted for, resulting in quantitative agreement between experiment and theory. FWM is then used to measure the early-time electron dynamics in the noble gas series from He to Xe following irradiation by an intense (10^14 Wcm-2) nonresonant 80 fs laser pulse. An electron impact ionization cooling model is presented to determine the evolution of electron kinetic energies following ionization. Kinetic energies are predicted to evolve from > 20 eV to < 1 eV in the first 1.5 ns. The initial degree of ionization is determined experimentally via measurement of the Bremsstrahlung background emission, and modeled with a modified ADK theory based on tunnel ionization. Combined, these two descriptions account for the evolution of both the electron temperature and concentration and provide quantitative agreement with the FWM measurements. The model is further tested with measurements of the gas pressure and pump laser intensity on the electron dynamics. The FWM experiments are concluded with a qualitative discussion of dissociative recombination dynamics occurring in molecular microplasmas. The microplasma environment is used as a source for the generation of two-level systems in the excited state manifold of atomic oxygen and argon. These two-level systems are coupled using moderately intense ~1 ps near-infrared (and near-resonant) pulses, resulting in Rabi sidebands with unprecedentedly large shifts in excess of 90 meV. A time-dependent generalized Rabi-cycling model is developed to account for the time-dependence of the laser electric field and subsequently the Rabi frequency. The Rabi radiation is determined to be coherent and tunable (up to 200 meV), providing a new method for ultrashort pulse generation. The dependence of the spectral positions of the Rabi sidebands on laser intensity affords the opportunity to simultaneously determine the ratios of transition dipole moments for the states accessed.
Temple University--Theses
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Hamadani, Kambiz Moshfegh. "Non-equilibrium single-molecule protein folding." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1672117101&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Busiello, Daniel Maria. "Entropy production in non-equilibrium systems." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3422682.
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In this thesis we study the entropy production of systems out of equilibrium. Initially we focus on discrete-state systems close to equilibrium amenable to be described by a master equation. It is possible to map the dynamics into a network of states, represented by nodes, connected by transition rates, identified by links. Using this framework, we analyze the entropy production of ensembles of randomly generated networks with specific constraints, for example size or symmetries, and identify the most important parameters which determine its value. This analysis provides an estimation for the entropy production based on a null-model that can be used for comparison with specific systems. In the second part of the thesis we investigate how coarse-graining influences our prediction of the physical properties of a system. For systems described by a Master Equation, the entropy production can be estimated using Schnakenberg's formula. On the other hand, some years ago Seifert derived an analogous formula for dynamics described by a Fokker-Planck. In this thesis, we aim at connecting both formulations, and starting from a Master-Equation system we calculate how Schnakenberg's entropy production is influenced by coarse-graining of the system. We show that such a value can be reduced to the Seifert's formula for some simple choices of the dynamics, but, surprisingly enough, we demonstrate that, in general, microscopic fluxes circulating in the system give a macroscopic non-negative contribution to the entropy production. As a consequence, neglecting information leads to an underestimation of the entropy production, and only a lower bound can be provided when the dynamics is coarse-grained. Finally, we study similarities and differences between non-equilibrium steady states and time-periodic driving in diffusive systems. A system that violates detailed balance evolves asymptotically into a steady state, which is not an equilibrium state since it has non-vanishing currents. Analogously, when detailed balance holds at any instant of time but the system is driven through time-periodic variations of external parameters, it evolves toward a time-periodic state, in which there are non-vanishing currents. In both cases the maintenance of currents throughout the system has a cost in terms of entropy production. Here we aim at comparing these two scenarios for a one dimensional continuous diffusive systems with periodic boundary condition, described by a Fokker-Planck equation, which is a natural framework to analyze molecular machines. First, we show that the entropy production is not equivalent in these two scenarios: the entropy production rate of a periodically driven system is always larger than the entropy production rate of a stationary system without detailed balance, when both are driving the same current and have the same averaged probability distribution. Next, we show constructively how to build both a non-equilibrium steady state and a periodic driving that support a given (time averaged) probabilities and current.In questa tesi studiamo la produzione di entropia in sistemi fuori dall'equilibrio. Nella prima parte ci concentriamo su sistemi con un numero finito di stati, vicini all'equilibrio termodinamico, che possono essere descritti da una Master Equation. Per sistemi di questo tipo è possibile mappare la dinamica in una rete di stati, rappresentati da nodi, collegati da rate di transizione, identificati da links. In questo contesto, analizziamo la produzione di entropia di ensemble di reti generate casualmente con vincoli specifici, ad esempio la taglia del sistema, e identifichiamo i parametri più importanti che ne determinano il valore. Questa analisi fornisce una stima per la produzione di entropia basata che può essere utilizzata come punto di partenza per il confronto con particolari sistemi di interesse. Nella seconda parte della tesi esaminiamo come il coarse-graining influenzi la nostra capacità di stimare alcune proprietà fisiche di un sistema. Per sistemi fuori dall’equilibrio descritti da una Master Equation, la produzione di entropia può essere stimata utilizzando la formula di Schnakenberg. D'altra parte, alcuni anni fa Seifert ha derivato una formula analoga per sistemi descritti da una Fokker-Planck Equation. In questa tesi miriamo a creare un ponte fra queste due formulazioni e, partendo da un sistema con un numero finito di stati calcoliamo come la produzione di entropia di Schnakenberg sia influenzata dalla procedura di coarse-graining. Mostriamo che tale valore può essere ridotto alla formula di Seifert per alcune scelte particolari della dinamica, ma che, abbastanza sorprendentemente, in generale i flussi microscopici presenti nel sistema danno un contributo macroscopico non negativo alla produzione di entropia. Di conseguenza, trascurare alcune informazioni porta a sottostimare la produzione di entropia, e solo un limite inferiore può essere fornito quando la dinamica è coarse-grained. Infine, nell’ultima sezione della tesi, studiamo somiglianze e differenze tra stati stazionari di non equilibrio e driving periodico in sistemi diffusivi. Un sistema che viola il bilancio dettagliato evolve asintoticamente in uno stato stazionario, che non è uno stato di equilibrio poiché presenta correnti non nulle. Analogamente, quando il bilancio dettagliato è presente in ogni istante di tempo, ma il sistema subisce variazioni periodiche dei parametri esterni, quest’ultimo evolve verso uno stato periodico in cui sono presenti correnti non nulle. In entrambi i casi il costo per produrre tali correnti in tutto il sistema è rappresentato dalla produzione di entropia. In questa tesi miriamo a confrontare questi due scenari per un sistema diffusivo continuo monodimensionale con condizioni al contorno periodiche, descritto da un'equazione di Fokker-Planck, che è il modo più naturale per analizzare le macchine molecolari. Innanzitutto, mostriamo che la produzione di entropia non è equivalente in questi due scenari: il rate di produzione di entropia in un sistema con driving periodico è sempre maggiore del rate di produzione di entropia in un sistema stazionario senza bilancio dettagliato, quando entrambi producono la stessa corrente e hanno la stessa distribuzione di probabilità (mediata nel tempo). Successivamente, mostriamo come costruire sia uno stato stazionario di non equilibrio sia un protocollo di variazione periodica dei parametri esterni che producano una data probabilità (mediata nel tempo) e una data corrente.
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Gatti, Nicola. "Laser diagnostics of non-equilibrium plasmas." Doctoral thesis, Università degli studi di Trento, 2018. https://hdl.handle.net/11572/367593.
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In the context of the electrification of the chemical industry, this thesis sets itself the goal of studying two promising plasma reactors: a nanosecond repetitively pulsed (NRP) discharge and a microwave discharge. The NRP reactor has been investigated for the dissociation of CO2. The microwave discharge has been used for studies of vibrational energy loading into N2 , as a first step towards the non-thermal synthesis of NO for fertilizer production. The complicated system that a non-equilibrium plasma represents requires sophisticated diagnostics. Such diagnostics have to be species specific and provide spatial and time resolved information about the quantities of interest, such as temperature (vibrational and rotational), product concentration and energy deposition. Given these require ments, diagnostics based upon the use of pulsed lasers are usually employed to study systems where fast kinetics are at play. The diagnostics of choice are Laser Induced Fluorescence (LIF) and vibrational Raman scattering.
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Cupani, Guido. "Non equilibrium dynamics of galaxy clusters." Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3065.
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2007/2008The thesis is focused on the dynamics of galaxies in the outskirts of galaxy clusters, where the matter is affected by an overall infall motion towards the cluster centre. Starting from the classical results of the spherical collapse model, we determined new theoretical constraints for the mass profile of clusters as a function of the cosmological parameters. We investigated the importance of the turnaround radius (i.e. the radius where the infall motion counterbalances the Hubble expansion motion) as well as the possibility of directly extracting the mass profile from the infall velocity pattern of member galaxies. The theoretical results were applied to a sample of simulated clusters (Borgani et al. 2004, Biviano et al. 2006) to keep the 3-dimensional dynamics under control. We demonstrated that: (1) most clusters are compatible with a single mass profile in the external region (provided their size and mass are normalized to the turnaround scale); (2) it is possible to extract the individual mass profiles of clusters using a selected subset of galaxies identified on their redshift-position distribution; (3) the Jeans equation and the virial theorem must be corrected in the outskirts of clusters to take into account the overall infall motion of matter. Taking advantage of these results, we developed a new technique for estimating the mass profile in cluster outskirts which only relies on the observational properties of member galaxies. This technique turns out to be simpler and more reliable than the current methods and is suitable to be applied to observations.
La tesi è incentrata sulla dinamica delle galassie nelle periferie degli ammassi di galassie, dove la materia è interessata da un moto complessivo di caduta verso il centro dell'ammasso. A partire dai risultati classici del modello di collasso sferico, abbiamo determinato dei nuovi vincoli teorici al profilo di massa degli ammassi in funzione dei parametri cosmologici. Abbiamo analizzato l'importanza del raggio di "turnaround" (ossia il raggio dove il moto di caduta è controblanciato dal moto di espansione di Hubble) e la possibilità di estrarre il profilo di massa direttamente dalla velocità di caduta delle galassie. Abbiamo poi applicato questi risultati teorici a un campione di ammassi simulati (Borgani et al. 2004, Biviano et al. 2006) per tenere sotto controllo la dinamica in tre dimensioni. Con quest'analisi, siamo stati in grado di dimostrare che: (1) la quasi totalità degli ammassi è compatibile con un unico profilo di massa nelle regioni esterne (purché le loro dimensioni e masse siano riscalate rispetto al raggio di turnaround); (2) è possibile estrarre il profilo individuale di un ammasso utilizzando un ristretto sottoinsieme di galassie, identificate dalla distribuzione dei loro redshift e delle loro posizioni; (3) l'equazione di Jeans e il teorema del viriale devono essere corretti nelle periferie degli ammassi in modo da tener conto del moto di caduta della materia. Grazie a questi risultati, abbiamo sviluppato una nuova tecnica per stimare il profilo di massa nelle zone esterne, basata unicamente sulle proprietà osservative delle galassie. Questa tecnica risulta essere più semplice e affidabile degli altri metodi attualmente utilizzati ed è adatta ad essere applicata alle osservazioni.
XXI Ciclo
1981
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Pechenik, Leonid. "Pattern formation and non-linear dynamics of non-equilibrium systems /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p9970653.
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Ecker, Christof. "Conformations of single polymer chains on surfaces non-equilibrium, equilibrium and manipulation /." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=976610140.
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Young, Michael J. (Michael Joseph). "Equilibrium and non-equilibrium phenomena in two- and three-dimensional correlated systems." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38386.
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Martinelli, Alessandro. "Density relaxations across the glass-transition under equilibrium and non-equilibrium conditions." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/302591.
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Cooling down a liquid below its melting temperature can lead to an amorphous frozen system commonly known as a glass. Despite glasses are common in everyday life, the nature of the glass transition still remains one of the most intriguing unsolved problems of condensed matter physics. In this Thesis the atomic length-scale rearrangements of glassy systems close to the glass transition temperature are explored under equilibrium and non-equilibrium conditions with X-Ray Photon Correlation Spectroscopy (XPCS). In particular, we explore the role of directional stresses on the dynamics in a colloidal glass of silica nanoparticles dispersed in a binary solvent. Our results show that the macroscopic stress stored in this glass relaxes via the cooperative ballistic motion of groups of particles with a characteristic size of the order of ten particle diameters. The role of stresses is further investigated in borate-based glasses, where the dynamics well below the glass transition are dictated by the recently discovered X-ray beam-induced dynamics. We show that these dynamics are related to the topology of the network, with peculiar similarities with the stress-phenomenology observed in colloids and metallic glasses.
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Martinelli, Alessandro. "Density relaxations across the glass-transition under equilibrium and non-equilibrium conditions." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/302591.
Full textAbstract:
Cooling down a liquid below its melting temperature can lead to an amorphous frozen system commonly known as a glass. Despite glasses are common in everyday life, the nature of the glass transition still remains one of the most intriguing unsolved problems of condensed matter physics. In this Thesis the atomic length-scale rearrangements of glassy systems close to the glass transition temperature are explored under equilibrium and non-equilibrium conditions with X-Ray Photon Correlation Spectroscopy (XPCS). In particular, we explore the role of directional stresses on the dynamics in a colloidal glass of silica nanoparticles dispersed in a binary solvent. Our results show that the macroscopic stress stored in this glass relaxes via the cooperative ballistic motion of groups of particles with a characteristic size of the order of ten particle diameters. The role of stresses is further investigated in borate-based glasses, where the dynamics well below the glass transition are dictated by the recently discovered X-ray beam-induced dynamics. We show that these dynamics are related to the topology of the network, with peculiar similarities with the stress-phenomenology observed in colloids and metallic glasses.
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DeSimone, Anthony Joseph Jr Gilmore Robert. "Symmetries and relaxations in non-equilibrium thermodynamics /." Philadelphia, Pa. : Drexel University, 2005. http://dspace.library.drexel.edu/handle/1860/483.
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Gustafsson, Alexander. "Modeling of non-equilibrium scanning probe microscopy." Licentiate thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-46448.
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The work in this thesis is basically divided into two related but separate investigations. The first part treats simple chemical reactions of adsorbate molecules on metallic surfaces, induced by means of a scanning tunneling probe (STM). The investigation serves as a parameter free extension to existing theories. The theoretical framework is based on a combination of density functional theory (DFT) and non-equilibrium Green's functions (NEGF). Tunneling electrons that pass the adsorbate molecule are assumed to heat up the molecule, and excite vibrations that directly correspond to the reaction coordinate. The theory is demonstrated for an OD molecule adsorbed on a bridge site on a Cu(110) surface, and critically compared to the corresponding experimental results. Both reaction rates and pathways are deduced, opening up the understanding of energy transfer between different configurational geometries, and suggests a deeper insight, and ultimately a higher control of the behaviour of adsorbate molecules on surfaces. The second part describes a method to calculate STM images in the low bias regime in order to overcome the limitations of localized orbital DFT in the weak coupling limit, i.e., for large vacuum gaps between a tip and the adsorbate molecule. The theory is based on Bardeen's approach to tunneling, where the orbitals computed by DFT are used together with the single-particle Green's function formalism, to accurately describe the orbitals far away from the surface/tip. In particular, the theory successfully reproduces the experimentally well-observed characteristic dip in the tunneling current for a carbon monoxide (CO) molecule adsorbed on a Cu(111) surface. Constant height/current STM images provide direct comparisons to experiments, and from the developed method further insights into elastic tunneling are gained.
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Shvarchuck, Igor Yevgeniiovich. "Bose-Einstein condensation into non-equilibrium states." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2003. http://dare.uva.nl/document/67440.
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Santos, Jaime Eduardo Moutinho. "Non-equilibrium dynamics of reaction-diffusion processes." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361994.
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Barrett-Freeman, Conrad. "Effects of advection on non-equilibrium systems." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/5846.
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We study a number of non-equilibrium models of interest to both active matter and biological physicists. Using microscopic agent-based simulation as well as numerical integration of stochastic PDEs, we uncover the non-trivial behaviour exhibited when active transport, or an advection field, is added to out of equilibrium systems. When gravity is included in the celebrated Fisher-Kolmogoro Petrovsky Piscouno (F-KPP) equation, to model sedimentation of active bacteria in a container, we observe a discontinuous phase transition between a `sedimentation' and a `growth' phase, which should in principle be observable in real systems. With the addition of multiplicative noise, the resulting model contains, as its limits, both the bacterial sedimentation previously described and the fluctuating hydrodynamic description of Directed Percolation (DP), an important and well-studied non-equilibrium system whose physics incorporate many universal features which are typical of systems with absorbing states. We map out the phase diagram describing all the systems in between these two limiting cases, finding that adding an advection term, however small, immediately lifts the resulting system out of the DP universality class. Furthermore, we find two distinct low-density phases separated by a dynamical phase transition reminiscent of a spinodal transition. Finally, we attempt to improve the current diffusion-limited model for the growth of filopodia, which are intriguing networks of actin fibres used by moving cells to sense their environment. By the addition of directed transport of actin monomers to the fibre tip complex by myosin molecular motors, we show that, under appropriate conditions, the resulting dynamics may be more efficient that transport by diffusion alone, which would result in filopodial lengths better corresponding to experimental observation.
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Flynn, Harry. "The non-equilibrium dynamics of blocked systems." Thesis, University of Derby, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489957.
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Packwood, David. "Non-equilibrium dynamics of discrete time Boltzmann." Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/10941.
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Lattice Boltzmann methods are a fully discrete model and numerical method for simulating fluid dynamics, historically they have been developed as a continuation of lattice gas systems. Another route to a lattice Boltzmann system is a discrete approximation to the Boltzmann equation. An analysis of lattice Boltzmann systems is usually performed from one of these directions. In this thesis the lattice Boltzmann method is presented ab initio as a fully discrete system in its own right. Using the Invariant Manifold hypothesis the microscopic and macroscopic fluid dynamics arising from such a model are found. In particular this analysis represents a validation for lattice Boltzmann methods far from equilibrium. Far from equilibrium, at high Reynolds or Mach numbers, lattice Boltzmann methods can exhibit stability problems. In this work a conditional stability theorem for lattice Boltzmann methods is established. Furthermore several practical numerical techniques for stabilizing lattice Boltzmann schemes are tested.
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Riesch, Christian. "Non-equilibrium dynamics in ordered modulated phases." Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-172821.
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In der vorliegenden Arbeit wird die Dynamik geordneter modulierter Phasen außerhalb des thermischen Gleichgewichts untersucht. Der Schwerpunkt liegt auf einem zweidimensionalen, streifenbildenden System, genannt Modell B mit Coulomb-Wechselwirkung, welches aus einem geordneten Anfangszustand unter dem Einfluß eines Rauschterms relaxiert. Aus den mittels numerischer Simulationen gewonnenen Daten wird die lokale Orientierung der Streifen extrahiert und deren raum-zeitliche Korrelationsfunktionen berechnet. Wir beobachten eine langsame Dynamik und Alterungseffekte in der Zwei-Zeit-Autokorrelationsfunktion, welche einer Skalenform folgt, die aus kritischen Systemen bekannt ist. Dies geht einher mit dem Wachstum einer räumlichen Korrelationslänge senkrecht zu den Streifen. Zu sehr späten Zeiten klingt die zugehörige räumliche Korrelationsfunktion mit einem Potenzgesetz ab. Weiterhin wird der Einfluß der Systemgröße und verschiedener Seitenverhältnisse auf die Dynamik des Orientierungsfeldes studiert, wobei ein Wachstumsprozeß parallel zur Ausrichtung der Streifen identifiziert wird. Es zeigt sich, daß dieser Prozeß für die Nichtgleichgewichtsdynamik entscheidend ist. Zwei weitere Modelle für modulierte Phasen werden in ähnlicher Weise untersucht. Die Swift-Hohenberg-Gleichung in der Variante mit erhaltenem sowie nicht erhaltenem Ordnungsparameter zeigt ebenfalls Alterungseffekte in der Dynamik der Streifenorientierung. In einem System, welches zweidimensionale hexagonale Muster bildet, werden Alterungseffekte in der Autokorrelationsfunktion der Verschiebung beobachtet. Jedoch sättigt die zugehörige räumliche Korrelationslänge bei einem endlichen Wert, was auf eine Unterbrechung der Alterung hindeutet.
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Kitagawa, Takuya. "New phenomena in non-equilibrium quantum physics." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10735.
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From its beginning in the early 20th century, quantum theory has become progressively more important especially due to its contributions to the development of technologies. Quantum mechanics is crucial for current technology such as semiconductors, and also holds promise for future technologies such as superconductors and quantum computing. Despite of the success of quantum theory, its applications have been mostly limited to equilibrium or static systems due to 1. lack of experimental controllability of non-equilibrium quantum systems 2. lack of theoretical frameworks to understand non-equilibrium dynamics. Consequently, physicists have not yet discovered too many interesting phenomena in non-equilibrium quantum systems from both theoretical and experimental point of view and thus, non-equilibrium quantum physics did not attract too much attentions.Physics
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Babadi, Mehrtash. "Non-equilibrium dynamics of artificial quantum matter." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11114.
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The rapid progress of the field of ultracold atoms during the past two decades has set new milestones in our control over matter. By cooling dilute atomic gases and molecules to nano-Kelvin temperatures, novel quantum mechanical states of matter can be realized and studied on a table-top experimental setup while bulk matter can be tailored to faithfully simulate abstract theoretical models. Two of such models which have witnessed significant experimental and theoretical attention are (1) the two-component Fermi gas with resonant $s$-wave interactions, and (2) the single-component Fermi gas with dipole-dipole interactions. This thesis is devoted to studying the non-equilibrium collective dynamics of these systems using the general framework of quantum kinetic theory.Physics
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Stewart, Andrew. "Non-equilibrium detectors for the mid-infrared." Thesis, Heriot-Watt University, 2003. http://hdl.handle.net/10399/275.
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Howard, Martin. "Non-equilibrium dynamics of reaction-diffusion systems." Thesis, University of Oxford, 1996. http://ora.ox.ac.uk/objects/uuid:4485a178-6262-4487-b40f-7c7ec790d687.
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Fluctuations are known to radically alter the behaviour of reaction-diffusion systems. Below a certain upper critical dimension dc , this effect results in the breakdown of traditional approaches, such as mean field rate equations. In this thesis we tackle this fluctuation problem by employing systematic field theoretic/renormalisation group methods, which enable perturbative calculations to be made below dc. We first consider a steady state reaction front formed in the two species irreversible reaction A + B → Ø. In one dimension we demonstrate that there are two components to the front - one an intrinsic width, and one caused by the ability of the centre of the front to wander. We make theoretical predictions for the shapes of these components, which are found to be in good agreement with our one dimensional simulations. In higher dimensions, where the intrinsic component dominates, we also make calculations for its asymptotic profile. Furthermore, fluctuation effects lead to a prediction of asymptotic power law tails in the intrinsic front in all dimensions. This effect causes high enough order spatial moments of a time dependent reaction front to exhibit multiscaling. The second system we consider is a time dependent multispecies reaction-diffusion system with three competing reactions A+A → Ø, B + B → Ø, and A + B → Ø, starting with homogeneous initial conditions. Using our field theoretic formalism we calculate the asymptotic density decay rates for the two species for d ≤ dc. These calculations are compared with other approximate methods, such as the Smoluchowski approach, and also with previous simulations and exact results.
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Faghfoor, M. Mohammad (Faghfoor Maghrebi). "Fluctuation-induced phenomena in non-equilibrium systems." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83826.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 128-134).
In this thesis, we investigate the implications of fluctuations in systems away, possibly even far, from equilibrium due to their motion either in or out of thermal equilibrium. This subject encompasses several topics in physics including the dynamical Casimir effect in the presence of moving boundaries, and non-contact friction between objects in relative motion. In both cases, photons are created due to the coupling of the motion and zero-point fluctuations in the vacuum, resulting in dissipation and radiative loss. We introduce a general formalism, equally applicable to lossy and ideal objects, to compute the quantum radiation and dissipation effects solely in terms of the classical scattering matrices. We obtain trace formulas which are general and independent of any approximation scheme where numerous examples, many novel, are discussed in great detail. Specifically, we give an exact treatment of quantum fluctuations in the context of a neutral rotating object, and show that it spontaneously emits photons and drags objects nearby, and compute the associated photon statistics and entropy generation. In the context of non-contact friction, we find a quantum analog of the classical Cherenkov effect for two neutral plates in relative motion, purely due to quantum fluctuations. We present a number of arguments and exact proofs, including a method introduced in the context of quantum field theory in curved space, as well as the scattering approach, to show that a friction force between two plates appears at a threshold velocity set by the speed of light in their medium.
by Mohammad F. Maghrebi.
Ph.D.
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Shea, Joan-Emma. "Brownian motion in a non-equilibrium bath." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42646.
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Silva, Giancarlo Thales Camilo da. "Non-equilibrium aspects of the holographic duality." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-09032017-113154/.
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This thesis is devoted to study far-from-equilibrium aspects of quantum systems at strong coupling using the holographic duality as a tool. The duality, originated from string theory and further generalized to broader scenarios, relates certain strongly coupled gauge theories to classical gravity theories in higher dimensions. Over the last years, it has proved itself useful as a calculational tool to map difficult questions of interest in the gauge theory into a dual (i.e., equivalent) problem in a higher-dimensional gravity language where the solution may become feasible. The interest in strongly coupled quantum field theories, in particular non-Abelian gauge theories, is motivated by a number of nuclear and condensed matter physics phenomena which are known to take place at a non-perturbative regime, such as the quark-gluon plasma phase of quantum chromodynamics or high-Tc superconducting materials. While dealing with strong coupling is typically a very hard task even at equilibrium, the situation becomes yet more dramatic when non-equilibrium setups are concerned since the main non-perturbative tool available nowadays lattice field theory suffers from serious problems when it comes to real-time dynamics. This is the reason why unconventional techniques such as the ones provided by holography are welcome. Of particular interest here are the problems of thermalization of strongly coupled plasmas as well as the quench dynamics of quantum systems, both of which admit a dual gravitational description involving time-dependent solutions to the corresponding classical equations of motion in the bulk of Anti de Sitter (AdS) spacetimes, such as collapsing solutions describing AdS black hole formation. Specifically, and always from a holographic point of view, in this thesis we deal with three classes of problems: the thermalization properties of a charged non-Abelian plasma after a sudden injection of energy (such as a heavy ion collision); the dynamics of a symmetry breaking quench process from a relativistic to a non-relativistic setup of the Lifshitz type with dynamical exponent z; and, finally, a new analytical approach to the non- equilibrium properties of conformal field theory plasmas placed in an expanding background. Apart from the specific problems, we also provide a self-contained but concise introduction to the holographic duality with a view towards newcomers with an elementary general relativity and quantum field theory background.Esta tese designa-se ao estudo de sistemas quânticos fortemente acoplados e fora do equilíbrio utilizando como ferramenta a dualidade holográfica. A dualidade, originária da teoria de cordas e posteriormente generalizada a cenários mais abrangentes, relaciona certas teorias de calibre fortemente acopladas e teorias de gravidade clássica em dimensões mais altas. Nos últimos anos, ela tem se mostrado útil como uma ferramenta de cálculo para mapear questões complicadas na teoria de gauge em um problema \\q{dual} (isto é, equivalente) formulado na linguagem completamente diferente de gravidade em dimensões extras, onde obter uma solução pode ser viável. O interesse em teorias quânticas de campo fortemente acopladas, em particular teorias de calibre não-Abelianas, motiva-se por uma variedade de fenômenos das físicas nuclear e da matéria condensada que, reconhecidamente, ocorrem em um regime não-perturbativo, tais como o plasma de quarks e glúons da cromodinâmica quântica ou certos materiais supercondutores com temperatura crítica alta. Em geral, lidar com acoplamentos fortes é uma tarefa bastante complicada mesmo em configurações de equilíbrio, mas a situação se torna ainda mais dramática quando configurações longe do equilíbrio são tratadas, visto que a principal ferramenta não-perturbativa disponível atualmente (teoria de campos na rede) enfrenta sérios problemas em situações dinâmicas. Esta é a principal razão pela qual técnicas alternativas tais como as fornecidas pela dualidade holográfica são bem vindas. De particular interesse aqui são os problemas da termalização de plasmas fortemente acoplados bem como a dinâmica pós-\\emph{quench} de sistemas quânticos, ambos os quais admitem uma descrição gravitacional dual envolvendo soluções dependentes do tempo às correspondentes equações gravitacionais em espaços-tempo de Anti de Sitter (AdS), tais como soluções de colapso descrevendo a formação de buracos negros assintoticamente AdS. Especificamente, e sempre sob um ponto de vista holográfico, nesta tese lidamos com três tipos diferentes de problemas: a termalização de um plasma não-Abeliano carregado como resultado de uma injeção repentina de energia (tal como uma colisão de íons pesados); a dinâmica durante um processo de quebra da simetria relativística para uma simetria não-relativística do tipo Lifshitz com expoente dinâmico $z$; e, finalmente, uma nova abordagem analítica para tratar propriedades fora do equílibrio de plasmas conformes colocados em um fundo que se expande. Além de tais problemas específicos, este texto fornece também uma introdução sucinta e auto-contida à dualidade holográfica direcionada a um leitor com conhecimento elementar de relatividade geral e teoria quântica de campos.