Rozprawy doktorskie na temat „Modèle URANS”
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Charrière, Boris. "Modélisation et simulation d'écoulements turbulents cavitants avec un modèle de transport de taux de vide". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAI108/document.
Pełny tekst źródłaThe computation of turbulent cavitating flows involves many difficulties both in modeling the physical phenomena and in the development of robust numerical methods. Indeed such flows are characterized by phase transitions and large density gradients, Mach number variation due to speed of sound decrease, two-phase turbulent areas and unsteadiness.This thesis follows experimental and numerical studies led at the Laboratoire des Ecoulements Géophysiques et Industriels which aim to improve the understanding and modeling of cavitating flows. Simulations are based on a compressible code coupled with a pre-conditionning technique which handles low-Mach number areas. The two-phase flows are reproduced using a one-fluid homogeneous model and temporal discretisation is performed using an implicit dual-time stepping method . The resolution is based on the RANS approach that couples conservation equations with firts-order closure models to compute eddy viscosity.In two-phase flows areas, the computation of thermodynamic quantities requires to close the system with equations of state (EOS). Thus, two formulations are investigated to determine the pressure in the mixture. The stiffened gas EOS is written with conservative quantities while a sinusoidal law deduces the pressure from the volume fraction of vapor (the void fraction). The present study improves the homogeneous equilibrium models by including a transport equation for the void ratio. The mass transfer between phases is assumed to be proportional to the divergence of the velocity. In addition to a better modeling of convection, expansion and collapse phenomenon, this added transport equation allows to relax the local thermodynamic equilibrium and to introduce a mestastable state to the vapor phase.2D and 3D simulations are performed on Venturi type geometries characterized by the development of unstable partial cavitation pockets. The goal is to reproduce unsteadiness linked to each profile such as the formation of a re-entrant jet or the quasi-periodic vapor clouds shedding. Numerical results highlight frequency variations of unsteadiness depending on the speed of sound computation. Moreover, the simulation conducted with a relaxed vapor density increase the pressure wave propagation magnitude generated by the collapse of cavitating structures. It contributes to the destabilization of the pocket. Finally, the role of the void ratio equation is analyzed by comparing the simulation results to those obtained subsequently from a model involving only three conservation equations
Alam, Boulos. "Modélisation numérique de la turbulence et de la dispersion atmosphérique par faibles vents en milieu urbain". Electronic Thesis or Diss., université Paris-Saclay, 2023. https://www.biblio.univ-evry.fr/theses/2023/interne/2023UPAST179.pdf.
Pełny tekst źródłaThis thesis is situated in the context of atmospheric dispersion modeling, particularly in the presence of low winds. Atmospheric pollution sources, often located near the ground and influenced by complex obstacles, generate high concentrations of pollutants nearby, resulting in significant concentration fluctuations. Low winds, typically associated with stable atmospheric conditions, pose a specific challenge in modeling pollutant dispersion, requiring a thorough analysis of meteorological data and adaptation of prediction models. To address this complex challenge, the use of Computational Fluid Dynamics (CFD) is necessary, although further research is needed to validate its effectiveness in the near-field and in the presence of low winds. The Code_Saturne® software (EDF R&D) is selected due to its proven efficiency in simulating atmospheric pollutant dispersion. This thesis is divided into three distinct phases : the first phase focuses on the fundamentals of atmospheric dispersion, exploring the impact of various parameters such as the atmospheric boundary layer structure, atmospheric turbulence, and atmospheric stability. These elements play a crucial role in how pollutants disperse in the air. The second phase details the methodology used in Code_Saturne for conducting simulations, including the turbulence models employed and the criteria for evaluating these models. In addition to traditional isotropic models, this research investigates the use of anisotropic turbulence models to study dispersion in various contexts. The third phase of the thesis concentrates on the evaluation of different turbulence models and velocity-scalar correlations using observations conducted in urban environments under neutral and stable atmospheric conditions. Finally, the last phase of the research explores conditions of low and stable winds, typically characterized by wind speeds below 2 m/s and random wind variations. This phase examines the meandering patterns in pollutant dispersion and assesses the limitations of analytical and CFD models in predicting concentration in such conditions. To this end, a URANS model is developed and evaluated. Ultimately, a segmented Gaussian method is devised to compare the results with CFD predictions and field observations
Fadai-Ghotbi, Atabak. "Modélisation de la turbulence en situation instationnaire par approches URANS et hybride RANS-LES : prise en compte des effets de paroi par pondération elliptique". Phd thesis, Université de Poitiers, 2007. http://tel.archives-ouvertes.fr/tel-00163592.
Pełny tekst źródłaGrondin, Julissa. "Analyse des instabilités et de la restabilisation d'un rouet centrifuge à régime partiel". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEC019.
Pełny tekst źródłaThis work presents a numerical investigation of the aerodynamic instabilities occurring in the centrifugal compressor Turbocel, which is currently tested at the LMFA laboratory. The study aims at better understanding the mechanisms of these instabilities, as well as the mechanisms of the restabilization which is observed in the compressor at low mass flow rates and partial regime. The computational domain is restricted to the isolated impeller without the other components of the stage (Inlet Guide Vane and radial diffuser). RANS and URANS simulations are carried out on a single channel of the impeller, with the elsA solver. RANS simulations are able to capture the strong increase in impeller pressure ratio, which is observed in the tests at low flow rate. The simulations show that this increase results from a strong rise in the work transferred to the flow by the blades. This coincides with the initiation of a reversed flow zone in the impeller inducer, in the zone between the main blades and the splitter blades leading edges. The first flow particles to reverse are those coming from a stall zone on the main blade leading edge, after they have gone up to the shroud and have been transported by the tip clearance flow. This recirculation zone extends towards both the hub and the inlet when the mass flow decreases. Secondly, URANS simulations are used to characterize the unsteady flow in the impeller. Albeit restricted to a single channel, these simulations capture the existence of rotating structures in the impeller inducer, at mass flow rates which correspond to the positively-sloped part of the pressure ratio performance curve obtained from RANS results. On the other hand, in the two negatively-sloped parts of the characteristic, the field remains steady and equal to the corresponding RANS solution. The simulated rotating structures differ from classical rotating stall because their propagation is due to a convection effect by the tip flow around the circumference, rather than a mass flow repartition between the different channels. The numerical results are then validated against experimental results, and against a full-annulus simulation as well. Without external perturbation, the results of the full-annulus and isolated channel simulations remain identical during the simulated time. In the computations the presence of such rotating instabilities coincides with mass flow rate oscillations in the whole computational domain. The latter are attributed to a mechanism of rotor-stator interaction between the blades and the stall cells, due to the fact that the number of blades and the number of stall cells are equal. Moreover, when these stall cells are observed in the simulations, the average performance of the impeller is higher than the RANS performance. Illustrative results with the analytical model of Moore-Greitzer for surge and rotating stall are presented in an axial configuration. They also result in a performance which stands above the steady, underlying characteristic of the compressor. Finally, the Moore-Greitzer model proves to be unable to capture the mass flow rate oscillations which are observed in the simulations. As an outlook, this suggests to integrate the rotor-stator interaction between the rotating stall cells and the blades in the analytical model, in order to improve the fast prediction of aerodynamic instabilities in the future
Dominguez, Bermudez Favio Enrique. "Simulation numérique de parcs d'hydroliennes à axe vertical carénées par une approche de type cylindre actif". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI020.
Pełny tekst źródłaThe capture, thanks to hydrokinetic turbines, of the kinetic energy generated by sea and river currents provides a significant and predictable source of renewable energy. The detailed simulation, using an unsteady statistical description of URANS type, of the flow around an isolated water turbine of HARVEST type (cross flow vertical axis ducted water turbine) provides an accurate estimate of the power output. However, the cost of the URANS approach is much too expensive to be applied to a farm of several turbines. A review of the literature leads to select a low-fidelity model of Blade Element Momentum (BEM) type to describe at a reduced cost the rotor effect on the flow, in a 2D context (horizontal cross-section). The turbine performance is then predicted using a steady RANS simulation including source terms distributed within a virtual rotor ring and preserving the mesh of the turbine fixed parts (duct). These source terms are derived using an original procedure which exploits both the local flow conditions upstream of the virtual rotor cells and the flow rate through the turbine. The hydrodynamic coefficients used to compute the BEM-RANS source terms are built once for all from a series of preliminary URANS simulations; they include the effects of the duct on the flow and the rotor operating at optimal rotational speed (maximizing the power output) thanks to the turbine regulation system. The BEM-RANS model is validated against reference URANS simulations: it provides a reliable prediction for the power output (within a few % of the URANS results) at a computational cost which is lowered by several orders of magnitude. This model is applied to the analysis of the power produced by a row of Vertical Axis Water Turbines in a channel for various values of the blockage ratio and lateral spacing as well as to a 3-machine sea farm
Junior, Silvio Rodrigues de Faria. "Genotipagem de poliplóides: um modelo de urnas e bolas". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/45/45133/tde-08092013-214551/.
Pełny tekst źródłaSince the beginnings of agriculture and livestock, the man selects individuals with desirable characteristics to breed and increase the proportion of new individuals with such qualities. With knowledge of the DNA structure and the advent of genetic engineering, the identification and characterization of individual species can make use of new technologies to help develop new varieties of plants and animals for many purposes. These technologies involve complex biochemical and physical procedures that produce even more accurated measures, like techniques that employ mass spectrometry to compare single nucleotide polymorphisms (SNPs). In plants it is common the occurrence of polyploidy, which is the presence of more than two chromosomes in the same group of homology. The determination of polyploidy level is essential for correct SNPs genotype calling and therefore greater efficiency in the study and genetic improvement of plants. In this work we characterize the phenomenon of poliploidy with probabilistic urns and balls models, proposing an efficient and appropriate method of simulation, as well as a simple technique to infer ploydy levels and classify biallelic samples accurately taking advantage of geometrical characteristics of the problem. Analysis of simulated and real data from an experiment of sugarcane were conducted with different measures of separation between groups and different experimental conditions. For the actual data, descriptive graphical methods show the correctness and consistency of the proposed method, which can be generalized to multi-allelic loci genotyping polyploid. We end our work comparing our results with the SuperMASSA [Serang2012] approach that brought excellent results to the problem. All code developed in language R were provided with the text.
Oliveira, Paulo Roberto de. "Modelos de urnas e loterias". Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/3960.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Many monthly, others weekly play in lottery games ignoring the randomness of the results, believing in luck or strategies that are sold to them in books about games. This monograph aims to show some concepts of probability and statistics unexplored in high school and also day to day situations that contain mathematical concepts of probability more accessible to this level of education showing some mathematical theories applied in practice games. Concepts will be discussed here: some probability distributions, their hope and variance, as well as lottery games and their probability calculations. Probability distributions will be calculated and listed in situations created from models of urns with two colors of balls, always having green as the color whose extraction will be considered successful and the red, whose extraction will be considered a failure. Now extractions with replacement balls will be made and sometimes extractions will be done without replacing them. Also, there is the case where new balls are added to both colors or one color.
Muitos jogam mensalmente, outros semanalmente, em jogos de loterias desconhecendo a aleatoriedade dos seus resultados, acreditando na sorte ou em estratégias que lhes são vendidas em livros sobre jogos. A presente monogra a tem como objetivo mostrar alguns conceitos da Probabilidade e Estatística não explorados no Ensino Médio e também situações do dia a dia que contenham conceitos matemáticos sobre Probabilidade mais acessíveis a este nível de ensino, mostrando um pouco de teorias matemáticas aplicadas na prática de jogos. Serão conceitos aqui discutidos: algumas distribuições de probabilidade, sua esperan ça e variância, além de jogos de loterias e seus cálculos de probabilidade. As distribuições de probabilidade serão enunciadas e calculadas em situações criadas a partir de modelos de urnas com duas cores de bolas, tendo sempre o verde como a cor cuja extração será considerada sucesso e, o vermelho, cuja extração será considerada insucesso. Ora serão feitas extrações com reposições das bolas e ora serão feitas extrações sem a reposição das mesmas. Também, há o caso em que serão adicionadas novas bolas de ambas as cores ou uma cor apenas.
Benyoucef, Farid. "Amélioration de la prévision des écoulements turbulents par une approche URANS avancée". Thesis, Toulouse, ISAE, 2013. http://www.theses.fr/2013ESAE0014/document.
Pełny tekst źródłaThis research work is meant to assess an upgraded URANS approach, namely the Scale-Adaptive Simulation (SAS). This method is similar to a conventional RANS approach (namelythe SSTmodel) in attached areas and is able to adapt the eddy-viscosity level in detached areas toensure the resolution, at least partially, of the turbulent structures. In a first part of this researchwork, an improvement of the SAS approach is suggestedto allowa better sensitivity of themodelto instabilities such as Kelvin-Helmholtz ones. This "improved" model is referred to as SAS-αLmodel. Both SAS and SAS-αL models were implemented in the ONERA Navier-Stokes solverelsA and both of themaswell as the SSTmodelwere tested on academic test cases : a cylinder in acrossflowat a high Reynolds number, a backward-facing step flowcorresponding to theDriver&Seegmiller experiment and the transonic flow over the M219 cavity experimentally investigatedby de Henshaw. The influence of the numerical parameters was deeply investigated and particularattention was paid to the high-order space-discretization schemes effects. The reliabilityof the SAS approach in an industrial framework was assessed on an aeronautic configurationnamely a nacelle de-icing device. Comparisons between the threemodels (SST, SAS and SAS-αL)and an experimental database available at ONERA - The French Aerospace Lab have shown thebetter accuracy of the SAS approach as well as the high potential of the SAS-αL model
Thiery, Mylène. "Modélisation numérique du tremblement sur profil d'aile supercritique". Toulouse, ENSAE, 2005. http://www.theses.fr/2005ESAE0022.
Pełny tekst źródłaAmmour, Dalila. "Highly resolved LES and tests of the effectiveness of different URANS models for the computation of challenging natural convection cases". Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/highly-resolved-les-and-tests-of-the-effectiveness-of-different-urans-models-for-the-computation-of-challenging-natural-convection-cases(bc3e7813-b1b0-4d5b-9f27-4e50180dff59).html.
Pełny tekst źródłaBennis, Anne-Claire. "Etude de quelques modèles de turbulence pour l'océanographie". Phd thesis, Université Rennes 1, 2008. http://tel.archives-ouvertes.fr/tel-00343712.
Pełny tekst źródłaValdunciel, i. Coll Julio. "Paisatge i models urbans contemporanis. Les comarques gironines (1979-2006): del "desarrollismo" a la globalització". Doctoral thesis, Universitat de Girona, 2011. http://hdl.handle.net/10803/32044.
Pełny tekst źródłaLa present Tesi doctoral conté una anàlisi quantitativa i qualitativa dels canvis en la forma i el paisatge urbans a les Comarques Gironines entre 1979 i 2006. La part teòrica situa la recerca en el marc del fenomen de la ciutat dispersa i parteix de la hipòtesi de la convergència cap a un model urbà global. La part empírica demostra aquest pressupost a través de l’estudi dels 522 plans parcials d’urbanisme aprovats durant aquest període. Els resultats permeten validar la consolidació del fenomen de la ciutat dispersa en tant que explosió de l’espai urbanitzat, difusió de la urbanització sobre el territori i aparició d’un nou paisatge cada cop més genèric, format per tres grans tipologies morfològiques: eixamples, urbanitzacions i polígons d’activitat econòmica. Tot plegat posa de manifest les carències que ha tingut el planejament per ordenar el creixement urbà, el debilitament de la ciutat com a projecte públic i una degradació del model de ciutat mediterrània.
Al-Sharif, Sharaf. "Computation of unsteady and non-equilibrium turbulent flows using Reynolds stress transport models". Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/computation-of-unsteady-and-nonequilibrium-turbulent-flows-using-reynolds-stress-transport-models(935dbd20-b049-4b62-9e1c-eebb261675e5).html.
Pełny tekst źródłaBonneau, Virginie. "Prévision du bruit d'interaction tonal et à large bande d'une soufflante de nouvelle génération en régime subsonique". Thesis, Poitiers, 2015. http://www.theses.fr/2015POIT2272.
Pełny tekst źródłaModern turbofans are characterized by rotor blades with large chords, as well as heterogeneous OGV with mechanical struts integrated.The aim of this thesis is to characterize the impact of these technological innovations on sources generation and sound radiation in the bypass duct due to the interaction of the rotor wakes with the OGV. This mechanism is mainly responsible in tonal and broadband noise emissions which are dealt separately.On one hand, a URANS computation of the rotor-stator row provides the periodic sources on the heterogeneous stator as well as the sound field in the bypass duct crossed by the struts. The expansion of sound models allows to access to the tonal spectra obtained either by propagating sources thanks to a model based on the acoustic analogy principle, or by the sound field directly issued from the CFD. Then, it is shown that the stator heterogeneity induces the appearance of the fundamental tone, and that the struts lead to standing waves in the bypass duct.On the other hand, the simulation of a complete rotor channel with a ZDES approach provides the turbulent wakes. These erturbations feed an acoustic code based on the Amiet theory to predict the broadband noise radiated in the bypass duct. Despite the cost, ZDES stays clear of restrictive assumptions and sensitive calibration of isotropic homogeneous turbulence models by providing data directly workable, leading to more accurate predictions. Each of numerical simulations and acoustic predictions is validated thanks to the measurements performed in the RACE test rig
Annaduzzaman, Md. "Chitosan biopolymer as an adsorbent for drinking water treatment : Investigation on Arsenic and Uranium". Licentiate thesis, KTH, Mark- och vattenteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-167973.
Pełny tekst źródłaI många länder världen runt (även i Sverige) orsakar metallers toxicitet besvärliga vattenkvalitetsproblem och utgör ett hot mot människors hälsa. Bland de toxiska metaller som finns i svenska vatten utgör arsenik och uran i dricksvatten allvarliga hälsorisker vid långvarig exposition då de kan orsaka cancer och neurologiska problem. Flertalet brunnar är installerade i kristallint berg och sedimentära bergarter och vattnet kommer vanligen från sprickor i berggrunden. Hanteringen av sådant vatten kan kräva reduktion av expositionen för arsenik- och uraninnehåll genom förbättrade processer och teknologier. Detta är ett angeläget problem som kräver en säker, pålitlig och ekovänlig teknologi att tillämpas innan vattnet distribueras. En rad olika behandlingssystem är tillgängliga men många av dem är inte lämpliga beroende på deras höga kostnad, den komplicerade tillämpningen och problem med hanteringen av restprodukter. I denna studie has biopolymeren chitosan, den näst vanligaste polymeren efter cellulosa, konstaterats vara en möjlig adsorbent för att avlägsna arsenik(V) och uran(VI) från vatten. Karakterisering av adsorbenten har också genomförts genom XRD, FTIR, SEM, UV och strålning i synligt ljus samt TGA/DTA undersökningar. Batch-tester i bänkskala har genomförts med användning av chitosan (DDA-85%) som adsorbent för att bestämma dess förmåga att avlägsna arsenik(V) och uran(VI)genom att variera fyra parametrar, nämligen kontakttid, pH, dos av chitosan och halt av föroreningen. Adsorptionsdata vid optimala förhållanden bestämdes genom tillämpning av Langmuir, Freundlich och Dubinin-Radushkhevic (D-R) isotermerna. Vidare tillämpades Lagergrens pseudo-first-order och pseudo-second-order kinetiska modell för att undersöka adsorptionsprocessen. Karakteriseringen av materialet visade förefintligheten av effektiva amino- (N-H), hydroxyl- (O-H) samt karboxylgrupper (C=O) i chitosan-polysackariden och att det är lätt nedbrytbart. Preliminära resultat visar att reduktionen av arsenik(V) och uran(VI) var 100 respektive 97,45 % efter 300 minuters kontakttid med optimalt pH på 6,0 respektive 7,0. De optimala doserna av adsorbent och den initiala koncentrationen var 60 och 80 g/L och 100 och 250 µg/L. Adsorptions process beskrevs bäst av Freundlich-isotermen för arsenik(V) (R2 = 0.9933) och med Langmuir-isotermen för uran(VI) (R2 = 0,9858) jämfört med andra isotermer vilket var en viktig indikation på en homogen monolager-adsorption. För både arsenik(V) och uran(VI) beskrev pseudo-second order adsorptionen bättre än pseudo-first-order. Second-order kinetiska regressionskoefficienten (R2) var 0.9959 och 0.9872 respektive. De ovanstående resultaten visar sammanfattningsvis att chitosan (DDA-85%) kan användas som en billig, pålitlig och miljövänlig behandlingsmetod av vatten för arsenik(V) och uran(VI).
QC 20150526
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Perachia, Florencia. "Estudio de la dinámica temporal de un modelo de urnas : probabilidades de primer pasaje y criticalidad auto-organizada". Bachelor's thesis, 2020. http://hdl.handle.net/11086/15293.
Pełny tekst źródłaEn este trabajo estudiamos una combinación de los clásicos modelos de urnas de Ehrenfest y del votante. En nuestro modelo, a cada paso temporal se efectúa el modelo de Ehrenfest con probabilidad α, o el del votante con probabilidad (1 − α). Este modelo puede ser visto como una caminata aleatoria unidimensional en una red finita. Analizamos los estados de equilibrio del sistema y determinamos una transición de fase para α = 1/N . Asimismo, definiendo el tamaño de avalancha como la cantidad de pasos necesarios para volver al estado de equilibrio por primera vez, estudiamos la distribuciones de tamaños de avalanchas y de retornos, para determinar si el comportamiento del sistema presenta, además, criticalidad auto- organizada. Desde el punto de vista de la sociofı́sica, este modelo representa un modelo de opinión, donde el cambio de opinión puede darse por interacción, (modelo del votante), o sin interacción, (modelo de Ehrenfest). Para valores de α relativamente chicos (∼ 1/N ), el sistema evoluciona a una sociedad polarizada.
In this work we present a combination of two classical urn models: Ehrenfest and voter . At every time step of our model either an Ehrenfest step is performed with probability \alpha or a voter step is performed with probability (1 − α). This model can be seen as an unidimensional random walk in a finite lattice. We analyzed the equilibrium states of the system and found a phase transition at α = 1/N. Furthermore, by defining the size of an avalanche as the amount of steps needed for the system to return to the equilibrium state for the first time, we studied the distribution of avalanches sizes and returns, in order to determine also if the system has Self-Organized Criticality. From the point of view of social physics this model represents an opinion model, where an agent can change its opinion by interacting with other agents (voter model) or without any interaction at all (Ehrenfest model). For relatively small α values (∼ 1 / N), the system evolves into a polarized society.
Fil: Perachia, Florencia. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.
Klein, Markus. "Starke Korrelationen in Festkörpern : von lokalisierten zu itineranten Elektronen". Doctoral thesis, 2009. https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-36459.
Pełny tekst źródłaIn this thesis angle-resolved photoemission investigations on diverse strongly- correlated systems were presented. It was shown that this technique gives a direct access to the low-energy excitations of a solid and therefore provides important information about its many-body physics. In particular the spectroscopic investigation of the sharp quasi-particle features near the Fermi edge gave information about the following points: 1. quantum phase transition: as already investigated in [27], it was shown that high resolution PES gives a direct access to the local energy scale TK. In the framework of a pertubative model, it was presented how small RKKY corrections influence the Kondo temperature. From the experimental evolution of TK(x) in CeCu6-xAux conclusions could be drawn about the quantum phase transition at T = 0. 2. Kondo lattice: an ordered CePt5/Pt(111) surface alloy was prepared and investigated by ARPES. The sharp spectra show the characteristics of a Kondo lattice: hybridization gaps and a strong renormalization of the band mass in the vicinity of the Fermi edge. With the aid of different excitation energies and measurements on an isostructural LaPt5 surface alloy it was shown, that these effects are due to a d f -mixing. For the first time, the transition from the single-impurity to the heavy-fermion regime could be observed by ARPES. 3. phase transitions: for FeSi and URu2Si2 the sensitivity of ARPES to small changes in the Fermi surface was shown in the temperature dependent spectra. The measurements reveal characteristic energies and temperatures of the phase transitions. Furthermore the bands which are involved in the phase transition and their effective masses m* could be quantified. In the case of URu2Si2 it was shown that a heavy-fermion band with m* = 40 me is affected by the hidden-order phase transition. 4. surface effects: besides CeCu6-xAux all samples showed significant surface contribution to the spectra. Excitation energy dependent measurements were found to be a good tool to distinguish between bulk and surface contributions. 5. theoretical models: despite the shared expression “strongly correlated systems” the compounds differ in their theoretical description: it was found that the physics of cerium systems (CeCu6, CePt5/Pt(111)) at T > TK can be described in the framework of the SIAM. However, at lower temperatures (T < TK) the signatures of coherence appear in the spectra. These can only be described by the PAM. Heavy dispersing bands have been observed for URu2Si2 and FeSi. Thus these systems must be described by a Hamiltonian with lattice properties, too. Especially the transition metal compound FeSi was shown to be no Kondo insulator. A description in the framework of a multi-band Hubbard Hamiltonian seems to be more appropriate for this compound