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Damewood, Liam James. "Theoretical Models of Spintronic Materials." Thesis, University of California, Davis, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3602035.
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In the past three decades, spintronic devices have played an important technological role. Half-metallic alloys have drawn much attention due to their special properties and promised spintronic applications. This dissertation describes some theoretical techniques used in first-principal calculations of alloys that may be useful for spintronic device applications with an emphasis on half-metallic ferromagnets. I consider three types of simple spintronic materials using a wide range of theoretical techniques. They are (a) transition metal based half-Heusler alloys, like CrMnSb, where the ordering of the two transition metal elements within the unit cell can cause the material to be ferromagnetic semiconductors or semiconductors with zero net magnetic moment, (b) half-Heusler alloys involving Li, like LiMnSi, where the Li stabilizes the structure and increases the magnetic moment of zinc blende half-metals by one Bohr magneton per formula unit, and (c) zinc blende alloys, like CrAs, where many-body techniques improve the fundamental gap by considering the physical effects of the local field. Also, I provide a survey of the theoretical models and numerical methods used to treat the above systems.
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Gray, M. D. "Theoretical models of galactic starbursts." Thesis, University of Sussex, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377053.
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Wåhlin, Pernilla. "Theoretical Actinide Chemistry – Methods and Models." Doctoral thesis, Stockholms universitet, Fysikum, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-54848.
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The chemistry of actinides in aqueous solution is important, and it is essential to build adequate conceptual models and develop methods applicable for actinide systems. The complex electronic structure makes benchmarking necessary. In the thesis a prototype reaction of the water exchange reaction for uranyl(VI), for both ground and luminescent states, described with a six-water model, was used to study the applicability of density functional methods on actinides and different solvation models. An excellent agreement between the wave function methods CCSD(T) and MP2 was obtained in the ground state, implying that near-minimal CASPT2 can be used with confidence for the reaction in the luminescent state of uranyl(VI), while density functionals are not suited to describe energetics for this type of reaction. There was an ambiguity concerning the position of the waters in the second hydration sphere. This issue was resolved by investigating a larger model, and prop- erly used the six-water model was found to adequately describe the water exchange reaction. The effect of solvation was investigated by comparing the results from conductor-like polarizable continuum models using two cavity models. Scattered numbers made it difficult to determine which solvation model to use. The final conclusion was that the water exchange reaction in the luminescent state of uranyl(VI) should be addressed with near-minimal CASPT2 and a solvation model without explicit cavities for hydrogens. Finally it was shown that no new chemistry appears in the luminescent state for this reaction. The thesis includes a methodological investigation of a multi-reference density functional method based on a range separation of the two-electron interaction. The method depends on a universal parameter, which has been determined for lighter elements. It is shown here that the same parameter could be used for actinides, a prerequisite for further development of the method. The results are in that sense promising.
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de, Kock J. P. "Pulse oximetry : theoretical and experimental models." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302928.
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Glossop, Matthew T. "Theoretical studies of Anderson impurity models." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365734.
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Enache, Andreea. "Structural Econometrics for Game Theoretical Models." Paris, EHESS, 2015. http://www.theses.fr/2015EHES0126.
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Cette thèse inclut quatre chapitres réunis autour d'un thème commun: les problèmes inverses dans les jeux stochastiques en information incomplète. L'objectif de cette thèse est d'étudier l'identification et l'estimation d'un paramètre fonctionnel dans le contexte des variables inobservables, situation courante dès qu'il y a une asymétrie d'information. On cherche à retrouver la distribution des primitives dans des modèles d'enchères et de la théorie des contrats à partir des variables observées et du concept d'équilibre "Bayesian Nash Equilibrium". La méthodologie d'identification et d'estimation dans tous les quatre essais est basée sur une réécriture du modèle économique en termes de quantiles et l'analyse économétrique est conduite entièrement dans un contexte non paramétrique. Néanmoins, pour une certaine classe de problèmes que l'on appelle "problèmes bien-posés", la vitesse de convergence de nos estimateurs est une vitesse paramétrique. En général, les modèles de la théorie des jeux mènent souvent à des problèmes inverses non-linéaires mal-posés. Cependant, les deux premiers essais de cette thèse traitent des exemples des problèmes inverses bien-posés (l'enchère au troisième prix et le modèle d'anti-sélection). Le troisième essai est une généralisation de la méthodologie proposée dans les deux premiers articles et introduit une nouvelle classe de problèmes bien-posés que l'on appelle "hazard-rate game models". Le dernier article étudie l'enchère au premier prix en utilisant l'approche par les quantiles ce qui permet d'obtenir, par opposition avec la littérature existante, une forme explicite pour la fonction des quantiles des variables latentesThis thesis consists of four essays articulated around the topic of inverse problems in games of incomplete information. The objective of the dissertation is to study the identification and the estimation of a functional parameter in a context of unobserved variables, situation often encountered in the presence of asymmetric information. We recover the distribution of primitives in auctions and contract-theory models using the data and the concept of Bayesian Nash Equilibrium. All chapters use a quantile approach both in terms of identification and estimation methodology. Another common feature is that all the economic issues are studied in a fully nonparametric setting. In spite of that, for a class of problems that turn out to be well-posed inverse problems, we find parametric speed of convergence for our estimators. Usually, many game-theoretical models belong to a class of ill-posed inverse problems. Nevertheless, the two first papers (the third-price auction model and the pure adverse selection model) of this thesis treat models that belong in fact to a class of well-posed inverse problems. The third essay generalizes the results of the first two articles by considering a general form for the strategy function of the game and introduces a new class of well-posed games called "hazard-rate game models". The last chapter of the dissertation studies the first-price auction model using the quantile approach which, by contrast with the existing literature, leads to a closed-form solution for the quantiles of the latent variables
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Arciero, Julia. "Theoretical Models of Blood Flow Regulation." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/195903.
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In normal tissues, blood supply is closely matched to tissue demand for wide ranges of oxygen demand and arterial pressure. This suggests that multiple mechanisms regulate blood flow. Theoretical models can be used to analyze these interacting mechanisms. One proposed mechanism for metabolic flow regulation involves the saturation-dependent release of ATP by red blood cells, which triggers an upstream conducted response signal and arteriolar vasodilation. To analyze this mechanism, oxygen and ATP levels are calculated along a flow pathway of seven representative segments, including two vasoactive arteriolar segments. The conducted response signal is dependent on ATP concentration. Arteriolar tone depends on the conducted response signal, local wall shear stress and wall tension. Arteriolar diameters are calculated based on vascular smooth muscle mechanics. The model can account for increases in perfusion consistent with experimental findings at low and moderate oxygen consumption rates despite the opposing effects of the myogenic and shear-dependent responses. Autoregulation, the maintenance of nearly constant blood flow as arterial pressure varies, is assessed in the presence or absence of the myogenic, shear-dependent and/or metabolic responses. The model results indicate that the combined effects of myogenic and metabolic regulation overcome the vasodilatory effect of the shear-dependent response to generate autoregulatory behavior. Capillary recruitment has been shown to increase the capacity for oxygen delivery during exercise. In the model, capillary density is assumed to depend on small arteriole diameter. The model predicts a significant increase in the range over which perfusion can be regulated when recruitment is included. Oscillations in diameter and tone are predicted under certain conditions, suggesting a novel mechanism for vasomotion. The conditions that give rise to oscillations are analyzed. It is shown that the appearance of oscillations depends in a complex way on a number of system parameters. In summary, the theoretical model provides a quantitative assessment of the myogenic, shear-dependent and metabolic responses that affect blood flow regulation and identifies a role for capillary recruitment and vasomotion in the control of blood flow.
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Shivani, Krishnamurthy Vikas. "Theoretical models for compressible vortex dynamics." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/47963.
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In this thesis, we study the effects of weak compressibility on staggered vortex streets, which are a ubiquitous phenomenon observed in nature. They are formed by fluid flowing past an obstacle, and can be found at several different length scales ranging from human length scales such as in water flowing under a bridge, to astronomical length scales such as planetary atmospheres, and beyond. They are of fundamental importance in fluid flows of interest to engineers and applied mathematicians alike. Yet, these vortex streets have not been studied as much theoretically. The classical exact solutions of Kármán are more than a century old, and used singular vortex models. The studies by Saffman and co-workers considered a vortex patch street, thus removing the singularity, however this study was numerical. Part of the difficulty in de-singularised models arises because of the unknown shape of the free-boundary of a finite-sized vortex. In particular, the effects of compressibility have not been taken into account in any theoretical investigation from first principles. We undertake a theoretical study of weakly compressible vortex streets, and obtain solutions to first-order for the velocity field. The vortices are modelled as hollow vortices, which are bounded regions of constant pressure with a non-zero circulation around them. For incompressible hollow vortex streets, exact solutions based on a conformal mapping approach were found by Crowdy and Green (2011). We perform a Rayleigh-Jansen (perturbation) analysis on these solutions, assuming isentropic flow of an ideal gas. We develop a novel method involving a rare use of complex analysis in studying compressible flows of this type. We utilise the Imai-Lamla formula [Imai (1942)] for the complex potential, which reduces the solution of the weakly compressible flow to computing analytic functions. Combining this with a conformal mapping approach, we solve the free-boundary problem by obtaining boundary value problems in multiply-connected pre-image domains (an annulus), which are solved through modern applications of classical methods. We utilise the machinery of the Schottky-Klein prime function for this domain, which helps in solving the boundary value problems for the analytic functions. We find that the speed of the vortex street changes due to compressibility, but the details of this change depends importantly on the area of the vortices. The vortex street is found to speed up for smaller areas and slow down at larger areas. The critical area of transition is found to be further dependant on the vortex configuration in the flow. We discuss the relationship of the present results with a few other known results in the context of different flows. We compare our results in the zero vortex size limit, to the results from a weakly compressible point vortex analysis undertaken in Crowdy and Krishnamurthy (2017b) and find agreement. Parts of the results in this thesis are reported as a paper Crowdy and Krishnamurthy (2017a). It is hoped that the present study leads to further studies on related problems such as the stability of vortex streets and vortex wake modelling for both incompressible and compressible flows. Other related problems likely to be influenced by this study include the free compressible vortex pair, which is important from the point-of-view of the theory of vortex sound.
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Hillhouse, Joel J., and Rob Turrisi. "Motivations for Indoor Tanning: Theoretical Models." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etsu-works/63.
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This chapter reviews the literature applying health behavior theories to indoor tanning. Few studies have tried to fit full versions of health behavior models to indoor tanning. Theoretical models from the family of theories referred to as the reasoned action approach (e.g., theory of planned behavior, behavioral alternative model, prototype willingness model, etc.) have been most commonly used to study indoor tanning. Results indicate that these models fit indoor tanning data moderately to extremely well. Two lesser known models, problem behavior theory and the terror management health model, have also demonstrated a reasonable fit. Two other common models, the health belief model and social cognitive theory, have never been fully tested with indoor tanning. However, key constructs from these models (e.g., perceived susceptibility and threat, modeling) have been used to understand indoor tanning. Empirical research conducted represents a solid start toward developing strong, comprehensive models of indoor tanning that can guide intervention efforts. This initial work needs to be expanded by conducting longitudinal studies and by including a broader age range in studies because the majority of existing work has focused on young adults. Incorporating findings related to tanning dependency, peer group affiliation, media influences and other constructs into these foundational models will also improve our understanding and ability to develop efficacious interventions to reduce engagement in this health risk behavior.
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Micheletti, Cristian. "Models with competing interactions." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318919.
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Gomshi, Nobary M. A. "Heavy quark fragmentation models." Thesis, Durham University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328988.
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McCarthy, J. F. "Physical models on random lattices." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235053.
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The thesis will consist of five main chapters. In Chapter 1 a general description of random lattices and their geometrical properties will be given as well as a discussion of the formulation of random lattice field theory. The details of the construction of random lattices will be given in an appendix. In Chapter 2 there will be a discussion of the results of a simulation of the XY-model on a two dimensional random lattice. This simulation was carried out with the intention of comparing the behaviour of the XY-model on regular and random lattices. Chapter 3 will contain the results of a simulation of percolation models on random lattices using the technique of invasion percolation. In Chapter 4 there will be a proof that the problem of continuum percolation of disks can be formulated as a particular correlated bond percolation problem on a two dimensional random lattice. A simulation of continuum percolation based on the result of this proof will be described. The final chapter, Chapter 5, will be about diffusion in invasion percolation clusters.
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Jenkins, D. R. "Nonlinear convection and solidification models." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372654.
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Sung, Shih-Ta. "Black hole entropy and models." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4677/.
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No universally accepted statistical explanation of black hole entropy exists up to now, therefore, it is worth another try. Admittedly, black hole entropy does not have to have a statistical origin. If the "black hole entropy" is called "black hole index" instead, someone might be lured to give it an economic explanation. Nonetheless, the only way to justify one's claim about the statistical origin of black hole entropy is to compute it statistically. This is the motivation for the construction of black hole models. In chapter 1, I first review the four laws of classical black hole mechanics which form the basis for the introduction of black hole thermodynamics. After observing the formal analogy between the four laws of the black hole mechanics and that of the ordinary thermodynamics, I further explore the thermodynamic properties of black holes in chapter 2 by reviewing the phenomenon of Hawking radiation and introducing the idea of black hole entropy. Three statistical explanations of black hole entropy are introduced in chapter 3. I will start with’t Hooft's brick wall model. Then, á la Brown and York, I review the approach based on the gravitational degrees of freedom via path integral. In the final part of this chapter, I present my own version of a quantum statistical explanation of black hole entropy by regarding a black hole as a cavity with thermal states inside. The final chapter will be devoted to the construction of black hole models to materialise the idea that a black hole, in some sense, can be regarded as a cavity where thermalised quantum states reside with quantised spectrum. These quantum states and the corresponding spectrum will then justify the statistical explanation of black hole entropy presented in the final section of chapter 3.
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Camp, Philip James. "Simple models of liquid crystals." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388019.
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Hendriks, Gert. "Theoretical models in bioanalytical method development development and use of theoretical models in pharmaceutical bioanalysis of small molecules /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2009. http://irsw.ub.rug/nl/ppn/316.
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Torracchi, Federico. "Essays in empirical and theoretical labor market models." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:4703d768-3796-42ce-ae6c-75c1f582db67.
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This DPhil thesis is a collection of three theoretical and empirical papers studying labor markets in several advanced economies. Two chapters examine the relationship between the banking sector and the labor market in the US and the UK, while one evaluates a policy that has been proposed to help labor markets in the Euro Area adjust to economic shocks. In the first chapter, I develop a New Keynesian DSGE model that integrates a banking sector subject to moral hazard with a standard random search model of the labor market. I estimate the model using US data and study the role of the banking sector in determining labor market fluctuations. In the second chapter, I estimate a structural VAR model of the UK and US economies and identify bank lending shocks using a mix of sign and short-run exclusion restrictions. Consistent with the predictions of the DSGE model, an expansionary loan supply shock decreases job-destruction and increases job-creation, reducing the unemployment rate persistently. Bank lending shocks are also important drivers of labor market fluctuations, particularly during the Great Recession. Lastly, in the third chapter, I calibrate to the Euro Area a currency union DSGE model to evaluate the aggregate properties of European Unemployment Insurance (EUI). I find that EUI cannot contemporaneously stabilize the monetary union and achieve convergence in regional unemployment and inflation rates.
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Suarez, Mauricio. "Models of the world, data-models and the practice of science : the semantics of quantum theory." Thesis, London School of Economics and Political Science (University of London), 1997. http://etheses.lse.ac.uk/2480/.
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The most important problems in the philosophy of quantum mechanics are the problem of measurement and the problem of the 'acausal' EPR correlations. It is commonly thought that these problems call for a new interpretation of the quantum theory. I argue that it is possible to construe both problems rather differently, as resulting from a mistaken understanding of scientific theory-application. It then becomes possible to tackle both problems independently of questions of interpretation, by attending carefully to what constitutes a successful application of a scientific theory, and of the quantum theory in particular. In the first part of the Thesis, I argue against a standard conception of scientific theory-application. This standard conception, which is often presupposed in the philosophical discussions of quantum mechanics, takes the applications of a scientific theory to constitute its domain of empirical adequacy. I argue that, on the contrary, a scientific theory can be applied to phenomena that it does not subsume. I present a case study in the history of superconductivity to illustrate and to motivate this claim. In the second part, I argue that the problem of measurement can be construed as the impossibility of applying the quantum theory to measurement interactions. I then argue that Arthur Fine's proposed solution to the measurement problem implicitly abandons the standard conception of application. Finally I look at quantum correlation phenomena. Bas Van Fraassen has claimed that the EPR correlations fit no causal model. The correctness of this claim depends on what probabilistic constraints a causal model is taken to have to satisfy. I argue, following Nancy Cartwright, that Van Fraassen's constraints on common-cause models are too strong; and I describe a direct-cause model that, I urge, constitutes a successful application of the quantum theory to the EPR correlations.
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Wohlgenannt, Michael. "Field Theoretical Models on Non-Commutative Spaces." Diss., lmu, 2003. http://nbn-resolving.de/urn:nbn:de:bvb:19-11342.
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Magic, Zazralt. "Theoretical stellar atmosphere models for cool stars." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-173446.
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In kühlen Sternen wie der Sonne wird die nuklear erzeugte Energie aus dem Inneren an die Oberfläche transportiert. Diese kann dann in den freien Weltraum entfliehen, und so können wir das Sternenlicht letztlich beobachten. Die theoretische Modellierung des photosphärischen Übergangsbereiches – vom konvektiven zum radiativen Energietransport – ist aufgrund der inhärenten dreidimensionalen (3D) Natur der Konvektion und der komplexen, nicht-linearen und nicht-lokalen Interaktionen des Strahlungsfelds mit dem stellaren Plasma sehr anspruchsvoll. Theoretische Atmosphärenmodelle stellen die fundamentale Basis für die Untersuchung von Sternen dar, daher sind Astronomen für ihr Verständnis der Sterne auf diese letztlich angewiesen. Die üblicherweise verwendeten eindimensionalen (1D) Atmosphärenmodelle beinhalten verschiedene Vereinfachungen. Insbesondere wird die Konvektion für gewöhnlich mit der Mischungswegtheorie berechnet, trotz ihrer wohlbekannten Fehler, da derzeit keine deutlich besseren Alternativen vorhanden sind. Der einzige Ausweg, um dieses Problem zu überwinden ist, die zeitabhängigen, dreidimensionalen, hydrodynamischen Gleichungen, welche mit einem realistischen Strahlungstransport gekoppelt sind, zu lösen. Aufgrund der in den vergangenen Jahrzehnten rasch gestiegenen Rechenleistung wurden bedeutende Fortschritte mit Simulationen für 3D Strahlungshydrodynamik (RHD) von Atmosphären erzielt. Diese Modelle sind außerordentlich leistungsfähig, und besitzen eine enorme Vorhersagekraft, wie präzise Vergleiche mit Sonnenbeobachtungen wiederholt beweisen konnten.
Ausgestattet mit diesen ausgereiften Methoden möchte ich als Ziel meiner Dissertation die drei folgenden Fragen näher untersuchen: Was sind die Eigenschaften der Atmosphären von kühlen Sternen? Welche Unterschiede sind zwischen den 1D und 3D Modellen vorhanden? Wie verändern sich die Vorhersagen für die Sternstrukturen und Spektrallinien? Um mich dieser Aufgabenstellung systematisch anzunehmen, habe ich das Stagger-Gitter berechnet. Das Stagger-Gitter ist ein umfangreiches Gitter aus 3D RHD Atmosphärenmodellen von kühlen Sternen, welches einen großen stellaren Parameterbereich abdeckt. In der vorliegenden Dissertation beschreibe ich die Methoden, welche angewendet wurden, um die vielen Atmosphärenmodelle zu berechnen. Zudem werden die allgemeinen Eigenschaften der resultierenden 3D Modelle, auch deren zeitliche und räumliche Mittelwerte detailliert dargestellt und diskutiert. Die Unterschiede zwischen den 1D und 3D Schichtungen, sowie die Details der stellaren Granulation (die Manifestation der Konvektion unterhalb der Sternoberfläche) werden ebenfalls umfangreich erläutert und beschrieben. Des Weiteren habe ich folgende Anwendungen für die 3D Atmosphärenmodelle untersucht: Berechnung theoretischer Spektrallinien, wichtig für die Bestimmung von Sternparametern, Spektroskopie und Häufigkeiten-Analyse; die sogenannte Randverdunkelung, notwendig für die Analyse interferometrischer Beobachtungen und Suche nach extrasolaren Planeten; und die Kalibrierung der Mischungsweglänge, womit 1D-Sternmodelle verbessert werden können.
Die Qualität der hochauflösenden Beobachtungen hat inzwischen die der theoretischen 1D Atmosphärenmodelle aufgrund der technischen Entwicklungen in den vergangenen Jahren überschritten. Daher hat sich der Bedarf an besseren Simulationen für Atmosphärenmodelle erhöht. Durch die Bereitstellung eines umfangreichen Gitters aus 3D RHD Atmosphärenmodellen wurde dazu ein erheblicher Beitrag geleistet. Damit werden wir den Anforderungen an die Theorie für die derzeitigen und zukünftigen Beobachtungen gerecht werden, und können somit zu einem besseren Verständnis der kühlen Sterne beitragen.In cool stars, like the Sun, energy from the inside is transported to its surface by convection, which then can escape into space as radiation that we can observe. Modeling this photospheric transition region – from convective to radiative energy transport – is notoriously challenging due to the inherent three-dimensional (3D) nature of convection itself and the complex non-linear and non-local interaction of the radiation field with the stellar plasma. Astronomers rely on theoretical atmosphere models, which provide the fundamental basis to study and understand stars. The commonly employed one-dimensional (1D) atmosphere models make use of several simplifications, in particular, convection is usually treated with the mixing-length theory (MLT), despite its well-known wrongness simply due to the lack of a considerably improved alternative. Therefore, the only appropriate approach to overcome this issue, is to solve the time-dependent, 3D, hydrodynamic equations coupled a with the realistic treatment of radiative transfer. Due to the soaring computational power in the recent decades, significant progress has been established with the advent of 3D radiative hydrodynamic (RHD) atmosphere simulations. Nowadays, these perform exceedingly well and offer exceptional predictive potential as detailed comparisons with the Sun have repeatedly revealed. Equipped with this matured, powerful tool, I want to address the following three main questions as the aim of my thesis: What are the atmospheric properties of cool stars besides the Sun? Which differences are given between 1D and 3D models? How do the application-based predictions change? To attend to this matter in a systematical approach, I have computed the Stagger-grid, a comprehensive grid of 3D RHD model atmospheres of cool stars covering a wide range in stellar parameters. In this thesis I describe the methods I have applied for the computation of the grid models, and the general properties of the 3D models, as well as their temporal and spatial averages are presented and discussed in detail. Also, the differences between 1D and 3D stratifications are determined, and the details of stellar granulation, the manifestation of subsurface convection, is extensively depicted. Furthermore, I investigated with the Stagger-grid several applications for 3D atmosphere simulations including: spectral line profiles, important for stellar parameter determination, stellar spectroscopy and abundance analysis; limb darkening, necessary for interferometry and extrasolar planet search; and the calibration of the mixing length, which will improve stellar evolution models. The cumulative technical developments of high-resolution observations in the recent years have surpassed the standards of theoretical 1D atmosphere models, thereby, it has given rise to the enhanced demand of improved atmosphere simulations. By providing a comprehensive grid of 3D RHD atmosphere models to the astronomical community, a major contribution has been achieved to live up to the current and future high-precision observations, which ultimately will lead to a better understanding of cool stars.
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Nicole, Robin Maxime Jacques. "Fluctuations and large deviationsin game theoretical models." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/fluctuations-and-large-deviationsin-game-theoretical-models(9123000e-e9c7-4c23-891c-ef1748ab3f4f).html.
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This thesis uses advanced methods from statistical physics to investigate collective effects in game theoretical models with a large number of players. Specifically, I study the strategy distributions in a large game that models how agents choose among double auction markets. I provide a classification of the possible mean field Nash equilibria, which include potentially segregated states where an agent population can split into subpopulations adopting different strategies. I compare this classification with the results of Experience-Weighted Attraction (EWA) learning, which in the long run leads to Nash equilibria in the appropriate limits of large intensity of choice, low noise (long agent memory) and perfect imputation of missing scores (fictitious play). Non-trivially, depending on how the relevant limits are taken, more than one type of equilibrium can be selected. These include the standard homogeneous mixed and heterogeneous pure states, but also heterogeneous mixed states in which different agents play different strategies that are not all pure. I also investigate the influence of heterogeneity in traders’ behaviour on the emergence of segregation described previously. The theoretical machinery is then extended from the study of systems with two markets, to the analysis of multi-agent systems where traders can choose between multiple markets. The last part of the thesis focuses on how the interaction among players in a repeated game can be represented as an evolutionary process in a “population of ideas”. I propose the interpretation of reinforcement learning as a stochastic process in a finite population of this type. The resulting birth-death dynamics has absorbing states and allows for the extinction of ideas, which marks a key difference with mutation-selection processes. I characterise the outcome of evolution in populations of ideas for several classes of symmetric and asymmetric games.
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Roper, Steven Michael. "Theoretical models for dyke geometries and trajectories." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614961.
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Kempe, Marius. "Experimental and theoretical models of cultural evolution." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/9513/.
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This thesis contributes to the field of cultural evolution by presenting two experimental and two theoretical models of cultural evolution. Prior to presenting these I survey existing experimental and theoretical models of cultural evolution. In the first experiment, I test the hypothesis that increasing group size speeds up cultural accumulation, using a novel puzzle-solving task and within a transmission chain design. I find support for this hypothesis, in contrast with previous experiments. In the second experiment, also using a transmission chain design, I examine perceptual errors in recreating Acheulean handaxes and ask whether such errors can account for the variability of Acheulean technology over time. Using the accumulated copying error model to compare the experimental data to archaeological records, I conclude that perceptual errors alone were likely not the driving force behind Acheulean evolution. In the first theoretical chapter, I present models of cultural differences between populations and of cumulative culture, which build on existing models and accord with empirical data. I then show that the models, when combined, have two qualitative regimes which may correspond to human and nonhuman culture. In the second theoretical chapter, I present a ‘fundamental theorem of cultural selection’, an equivalent of Fisher’s Fundamental Theorem of Natural Selection for cultural evolution. I discuss how this theorem formalizes and sheds light on cultural evolutionary theory. Finally I conclude and discuss future research directions.
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Billig, Ian A. "Bayesian Analysis of Systematic Theoretical Errors Models." Ohio University Honors Tutorial College / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors155619979679762.
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Guidi, Giacomo <1992>. "Price manipulation: theoretical models and empirical investigation." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10349/1/Phd%20Thesis%20Guidi%20Giacomo.pdf.
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Understanding why market manipulation is conducted, under which conditions it is the most profitable and investigating the magnitude of these practices are crucial questions for financial regulators. Closing price manipulation induced by derivatives’ expiration is the primary subject of this thesis. The first chapter provides a mathematical framework in continuous time to study the incentive to manipulate a set of securities induced by a derivative position. An agent holding a European-type contingent claim, depending on the price of a basket of underlying securities, is considered. The agent can affect the price of the underlying securities by trading on each of them before expiration. The elements of novelty are at least twofold: (1) a multi-asset market is considered; (2) the problem is solved by means of both classic optimisation and stochastic control techniques. Both linear and option payoffs are considered. In the second chapter an empirical investigation is conducted on the existence of expiration day effects on the UK equity market. Intraday data on FTSE 350 stocks over a six-year period from 2015-2020 are used. The results show that the expiration of index derivatives is associated with a rise in both trading activity and volatility, together with significant price distortions. The expiration of single stock options appears to have little to no impact on the underlying securities. The last chapter examines the existence of patterns in line with closing price manipulation of UK stocks on option expiration days. The main contributions are threefold: (1) this is one of the few empirical studies on manipulation induced by the options market; (2) proprietary equity orderbook and transaction data sets are used to define manipulation proxies, providing a more detailed analysis; (3) the behaviour of proprietary trading firms is studied. Despite the industry concerns, no evidence is found of this type of manipulative behaviour.
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Wilmott, P. "The asymptotic solution of models in theoretical mechanics." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354870.
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Frade, Carlos Augusto Zerpa. "Performance of return models : a portfolio theoretical approach." Master's thesis, Instituto Superior de Economia e Gestão, 2017. http://hdl.handle.net/10400.5/14699.
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Mestrado em FinançasO objetivo desta investigação é avaliar o impacto das assunções dos modelos geradores de retornos nas fronteira eficiente e seus portafolios. Isto foi conseguido mediante o trabalho in-sample (assim eliminando o risco de estimação, focando a investigação no risco de modelo) em ambos mercados de ativos financeiros, o Europeo e Americano, nos 7 anos anteriores, considerando ambos, o caso em que shortselling esta permitido como também o caso em que esta proibido. O processo inclui o calculo da fronteira eficiente seguindo as assunções dos modelos geradores de retornos. Em particular o Constant Correlation Model (CCM), o Single-Index Model (SIM) e o modelo de tres factores de Fama e French (1993) Multi-Factor Model (MFM). Para os dois mercados de investimentos, comparamos a fronteira eficiente gerada aplicando MVT nos dados in-sample com a fronteira eficiente dos modelos de retorno seleccionados. Mostramos que o risco do model è importante na aplicação do MVT. Sendo os erros encontrados em todos os modelos consideravel. Também, considerando o risco de modelo para o caso de shortselling proibido, o CCM mostra melhor desempenho que os modelos mais sofisticados. Por outra parte, em condiçoes de shortselling permitido, o SIM mostra melhor desempenho.
The objective of this research is evaluating the impact of the return generating models assumptions in the efficient frontier and its portfolios. This is accomplished by working with in-sample data (eliminating the estimation risk and focus on the model risk) looking at both the European and American stock markets for the past 7 years, and considering both, the case when shortselling is allowed and the case when it is forbidden. The process includes the calculation of efficient frontier under the assumptions of return generating models. In particular, we look at the Constant Correlation Model (CCM), the Single-Index Model (SIM) and the three factors Fama and French (1993) Multi-Factor Model (MFM). For both markets we compared the true efficient frontier generated from the in-sample MVT with the corresponding efficient frontiers from the return generating models. We show model risk is an important issue when applying MVT. The errors in all model are considerable. In addition, considering model risk for cases when the short-sell is not allowed, the CCM is more accurate than more sophisticated models. On the other hand, under conditions of short-sell allowed, the SIM seams to be more accurate.
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Weston, Robert Andrew. "Lattice field theory and statistical-mechanical models." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315971.
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Dickens, Nigel L. "Quantum impurity models : a local moment approach." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270010.
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Rashid, Maher S. "Quasi-integrable models in (2+1) dimensions." Thesis, Durham University, 1992. http://etheses.dur.ac.uk/5780/.
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Recently σ-models have received a lot of attention for many reasons. One interesting aspect of the CP(^n) sigma models is the fact they are the simplest Lorentz invariant models which possess topologically stable (minimum of the action) solutions in (2+0) dimensions. Unfortunately, it appears that Lorentz covariance and integrability are incompatable in (2+1) dimensions. In the literature a few integrable models were constructed in (2+1) dimensions at the expense of Lorentz invariance (e.g. modified chiral model,...). An alternative way to proceed is to retain Lorentz invariance and relax the property of integrability by replacing it with a new property of quasi-integrability. Zakrzewski and others have constructed an example of such quasi-integrable models. Their example is based on the CP(^1) model modified by the addition of two stabilising terms (the first called the "Skyrme-like" term and the second the "potential-like" term) to the basic Lagrangian. In this thesis we have addressed the following relevant questions: How unique is this model? What are the properties of its static structures (skyrmions)? Is it possible to generalise this model? Is quasi-integrabilty, as a property, shared by all CP(^2) models, or it is only restricted to the CP(^1) model? It turns out that the first stabilising term [i.e the Skyrme-like term) is only unique for CP(^1) model and this uniqueness does not survive the generalisations to larger coset spaces, say, CP(^n). The second stabilising term is not unique. By taking advantage of this observation, i.e arbitrariness of the potential term, a generalisation of Zakrzewski's model has become possible. Most important of all is the fact that all the CP" models are quasi-integrable provided one incurs the size instabilities of their soliton solutions.
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Yannacopoulos, A. N. "Diffusion models in strongly chaotic Hamiltonian systems." Thesis, University of Warwick, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357654.
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Ceballos, Myriam Mondragon. "The low-energy structure of compactified superstring models." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291440.
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Sanchez, Marcela Beltran. "Models of defects near Si/SiOâ†2 interfaces." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303579.
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Burnham, Christian James. "Structural and dynamical properties of mathematical water models." Thesis, University of Salford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299208.
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Rayner, David Andrew James. "Type I string phenomenology and extra dimensional models." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249946.
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Thorpe, Richard N. "Theoretical and computational models of active galactic nuclei." Thesis, University of Leicester, 2000. http://hdl.handle.net/2381/30628.
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This thesis discusses the origin of the broad emission lines seen in active galactic nuclei (AGN), in the context of a disc-wind model. An out-flowing nuclear wind generates Kelvin-Helmholtz instabilities within the atmosphere of an accretion disc, which surrounds a super-massive (~ 3 x 10 7 M⊙ ) black hole. The broad line region (BLR) clouds are a direct result of this interaction. The BLR clouds reach velocities required to explain the broad-bases of the permitted lines, within a few sound crossing times, and are destroyed on a similar time scale. We examine NGC5548, and NGC4151 in detail, and conclude that both sources have a small inner BLR radius (1016 cm). By using near simultaneous CIV and Hbeta profiles of NGC.5.548 it is possible to examine the optical and UV spectral regions simultaneously. Observed continuum light curves were used to predict line light curves. Comparisons with observation indicate that the inner and outer BLR radius, ionisation parameter, column and particle density, for both sources are plausible. I examine NGC4151 in detail, particularly the CIV line. The line probably comprises more components than the simpler configuration in NGC5548. For example, reflection of CIV line photons off of a surface subtending a solid angle larger than 2pi, can explain the excess flux in the long-wavelength side of the line, and why this is seen to respond before the short-wavelength side, without invoking in-falling clouds. It is possible to rule out the BLR clouds as directly responsible for the UV absorption. However, the cloud-wind interaction is shown to provide a source of highly ionised, low-column density material, that could be the source of UV absorption. This material covers a large solid angle, which implies that a significant fraction (~ 30%) of Seyfert-1s should show an absorbing component.
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Volkmann, Jörg. "Exhaust systems' models investigation by theoretical group methods." Göttingen Cuvillier, 2007.
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Govind, Niranjan. "Theoretical study of models for driven interface dynamics." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56667.
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In this dissertation, we review the physics associated with surfaces and interfaces in equilibrium and non-equilibrium. Our emphasis will be on interfaces that are driven far away from equilibrium with special interest in the phenomenon of kinetic roughening. Models which describe non-equilibrium interfaces will be introduced and analyzed using techniques such as the Renormalization Group, Monte Carlo simulations, and direct integration of the equation of motion. Different interface relaxation mechanisms will be discussed with a focus on surface diffusion, which is believed to be the dominant effect in Molecular Beam Epitaxy. These interface growth models generate self-affine structures with various correlations satisfying a dynamic scaling law. We compute the scaling exponents and functions. Finally, we study the effect of quenched impurities on the dynamics of a driven interface with a conservation law. The impurity effect leads to anomalous scaling exponents and qualitatively changes the interface dynamics. Our results are summarized in two articles to be published: Refs. (Govind and Guo, 1992; Govind, Guo and Grant, 1992).
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Rowan, David Glenn. "Theoretical studies of disordered short-range spin models." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299226.
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Kendall, Toby. "Theoretical models of trade blocs and integrated markets." Thesis, University of Warwick, 2000. http://wrap.warwick.ac.uk/4014/.
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This thesis consists of four main chapters, together with a general introduction and conclusion. The thesis examines, both separately and together, the formation of trade blocs and global market integration. All the models use a partial equilibrium framework, with firms competing as Cournot oligopolists. Chapter 2 presents two models of trade bloc formation under segmented markets. In the first model, with common constant marginal costs, global free trade is optimal for all countries when there are no more than four countries, but with five or more countries there is an incentive to form a trade bloc containing most countries, but excluding at least one. The second model introduces a cost function where a firm's marginal cost is lower when it is located in a larger trade bloc, with little effect on the results. Chapter 3 analyses the formation of trade blocs between countries with different market sizes under segmented markets. The formation of a two country customs union or free trade area will always raise the smaller country's welfare, while the larger country will usually lose from a free trade area, and sometimes from a customs union. Chapter 4, which is joint work with David R. Collie and Morten Hviid, presents a model of strategic trade policy under integrated markets, under complete and incomplete information. In the former case, a low cost country will give an export subsidy which is fully countervailed by the high cost country's import tariff. In the simultaneous signalling game, each country's expected welfare is higher than under free trade. Chapter 5 considers models of trade bloc formation under integrated markets. With common constant costs, there is no incentive for blocs to form. When costs are decreasing in membership of a bloc, either global free trade is optimal or countries would prefer to belong to the smaller of two blocs.
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Jenkins, Stephen Allen. "Theoretical models of eddy current interaction with defects." Thesis, University of Surrey, 1991. http://epubs.surrey.ac.uk/1047/.
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Dong, Yingying. "Microeconometric Models with Endogeneity -- Theoretical and Empirical Studies." Thesis, Boston College, 2009. http://hdl.handle.net/2345/753.
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Thesis advisor: Arthur LewbelThis dissertation consists of three independent essays in applied microeconomics and econometrics. Essay 1 investigates the issue why individuals with health insurance use more health care. One obvious reason is that health care is cheaper for the insured. But additionally, having insurance can encourage unhealthy behavior via moral hazard. The effect of health insurance on medical utilization has been extensively studied; however, previous work has mostly ignored the effect of insurance on behavior and how that in turn affects medical utilization. This essay examines these distinct effects. The increased medical utilization due to reduced prices may help the insured maintain good health, while that due to increased unhealthy behavior does not, so distinguishing these two effects has important policy implications. A two-period dynamic forward-looking model is constructed to derive the structural causal relationships among the decision to buy insurance, health behaviors (drinking, smoking, and exercise), and medical utilization. The model shows how exogenous changes in insurance prices and past behaviors can identify the direct and indirect effects of insurance on medical utilization. An empirical analysis also distinguishes between intensive and extensive margins (e.g., changes in the number of drinkers vs. the amount of alcohol consumed) of the insurance effect, which turns out to be empirically important. Health insurance is found to encourage less healthy behavior, particularly heavy drinking, but this does not yield a short term perceptible increase in doctor or hospital visits. The effects of health insurance are primarily found at the intensive margin, e.g., health insurance may not cause a non-drinker to take up drinking, while it encourages a heavy drinker to drink even more. These results suggest that to counteract behavioral moral hazard, health insurance should be coupled with incentives that target individuals who currently engage in unhealthy behaviors, such as heavy drinkers. Essay 2 examines the effect of repeating kindergarten on the retained children's academic performance. Although most existing research concludes that grade retention generates no benefits for retainees' later academic performance, holding low achieving children back has been a popular practice for decades. Drawing on a recently collected nationally representative data set in the US, this paper estimates the causal effect of kindergarten retention on the retained children's later academic performance. Since children are observed being held back only when they enroll in schools that permit retention, this paper jointly models 1) the decision of entering a school allowing for kindergarten retention, 2) the decision of undergoing a retention treatment in kindergarten, and 3) children's academic performance in higher grades. The retention treatment is modeled as a binary choice with sample selection. The outcome equations are linear regressions including the kindergarten retention dummy as an endogenous regressor with a correlated random coefficient. A control function estimator is developed for estimating the resulting double-hurdle treatment model, which allows for unobserved heterogeneity in the retention effect. As a comparison, a nonparametric bias-corrected nearest neighbor matching estimator is also implemented. Holding children back in kindergarten is found to have positive but diminishing effects on their academic performance up to the third grade. Essay 3 proves the semiparametric identification of a binary choice model having an endogenous regressor without relying on outside instruments. A simple estimator and a test for endogeneity are provided based on this identification. These results are applied to analyze working age male's migration within the US, where labor income is potentially endogenous. Identification relies on the fact that the migration probability among workers is close to linear in age while labor income is nonlinear in age(when both are nonparametrically estimated). Using data from the PSID, this study finds that labor income is endogenous and that ignoring this endogeneity leads to downward bias in the estimated effect of labor income on the migration probability
Thesis (PhD) — Boston College, 2009
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Economics
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Burton, III Jackson Kemper, and III Jackson Kemper Burton. "Theoretical Models for Drug Delivery to Solid Tumors." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621828.
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A cancer drug's effectiveness is contingent upon on its ability to reach all parts of the tumor. The distribution of drug in the tumor depends on several transport processes and depends on the physicochemical properties of the drug. These factors can lead to highly heterogeneous distributions of drug in the tumor interstitial space, leaving parts of the tumor unreached, and make it difficult to predict cellular exposure and understand its dependence on key system parameters. Theoretical models are powerful tools that can provide insight by simulating conditions that cannot be achieved or observed experimentally. Here, a Green's function method is utilized to simulate three-dimensional time-dependent diffusion and uptake of drugs in solid tumors with realistic vascular geometry. Regimes dependent on the time scales for transport are used to determine whether spatial and temporal effects must be resolved to predict cellular exposure. Simulations are performed to show the relationship between the plasma pharmacokinetics and cellular exposure for these regimes. Steep gradients in concentration arise when time scales for diffusion and uptake are comparable, implying that models based on well mixed compartments are inaccurate. Effects of linear and nonlinear kinetics of drug uptake on cellular exposure are demonstrated. The drug doxorubicin is commonly used against solid tumors. Cellular exposure to doxorubicin is complicated in vivo by its transport and physicochemical properties. The Green's function method is used to describe the in vivo transport and kinetics of doxorubicin, using parameters derived from in vitro results. Simulations show agreement with observed in vivo distributions of doxorubicin in tumor tissue as well as in vitro kinetics, and provide a link between the two types of experimental observations. The method is applied to the class of cancer drugs called antibody-drug conjugates (ADCs) which consist of a humanized antibody conjugated to extremely toxic small molecular weight drugs. ADCs exhibit complex in vivo kinetics dependent on many design parameters. A phenomenon exhibited by ADCs is the bystander effect, i.e. non-targeted cell killing, which is difficult to analyze based on in vivo observations. Simulations results agree with the observed in vivo distribution of ADCs in tumor tissue and with experimentally observed bystander effects. In summary, the the models presented here provide a novel approach for simulating the complex transport and cellular uptake kinetics exhibited by several cancer drugs. The models give a mechanistic basis for predicting cellular exposure to drugs which can aid, explain, and direct experimental approaches for improving cancer treatment.
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Devonald, Luke. "Theoretical models of sports leagues and other contests." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/theoretical-models-of-sports-leagues-and-other-contests(95eddb3d-4d15-45d0-8473-d7aec3d31541).html.
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The thesis consists of three separate chapters all of which investigate Theoretical Models of Sports Leagues and Other Contests. Chapter One outlines a new approach for modelling sports leagues, which complements traditional analyses of clubs' off-field talent recruitments with a subsequent analysis of players' on-field efforts. Most notably, the approach reveals a new theoretical basis for the hypothesis that sports fans prefer outcome uncertainty. Chapter Two provides a new theoretical model of the soft budget constraint phenomenon, in which governments provide bailouts for loss-making clubs in European soccer leagues. Most notably, the model indicates that governments provide an inefficiently high level of bailout funding to clubs. However, the model reveals that some positive level of bailout funding may be optimal. Chapter Three analyses a generic contest model with the possibility of a draw; an outcome in which no contestant is the winner. Most notably, our analysis reveals that introducing the possibility of a draw reduces homogeneous contestants' efforts. However, with heterogeneous contestants, introducing the possibility of a draw may induce greater effort from the strongest contestant.
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Naugle, Cameron R. "Rotordynamic Analysis of Theoretical Models and Experimental Systems." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1867.
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This thesis is intended to provide fundamental information for the construction and
analysis of rotordynamic theoretical models, and their comparison the experimental
systems. Finite Element Method (FEM) is used to construct models using Timoshenko
beam elements with viscous and hysteretic internal damping. Eigenvalues
and eigenvectors of state space equations are used to perform stability analysis, produce
critical speed maps, and visualize mode shapes. Frequency domain analysis
of theoretical models is used to provide Bode diagrams and in experimental data
full spectrum cascade plots. Experimental and theoretical model analyses are used
to optimize the control algorithm for an Active Magnetic Bearing on an overhung
rotor.
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Goffi, Gianluca. "Tourism destination competitiveness: theoretical models and empirical evidence." Doctoral thesis, Università Politecnica delle Marche, 2013. http://hdl.handle.net/11566/242690.
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La competitività delle destinazioni turistiche è uno dei temi più studiati in letteratura ed è il
principale fattore di successo di una destinazione. Molti studi si sono focalizzati sui fattori che
incidono sulla competitività di una destinazione. Nonostante ciò, non vi è ancora un’evidenza
scientifica dell’impatto di tali fattori sulle performance di una destinazione: questo studio si
pone quindi questo obiettivo, adattando ed estendendo il modello di Ritchie e Crouch e
applicandolo ad un dataset di 610 destinazioni di eccellenza italiane medio-piccole. Per ridurre il
numero delle variabili, è stata applicata un’analisi delle componenti principali. La dipendenza fra
gli indicatori di performance e le variabili dipendenti è stata analizzata attraverso una
regressione lineare e una regressione parziale dei minimi quadrati.
I risultati empirici dimostrano che una politica turistica e una gestione della destinazione
turistica sostenibile, non solo è importante per la protezione dell’ambiente e per minimizzare gli
impatti negativi di tipo socio-culturale, ma ha una notevole rilevanza nel migliorare la
competitività di una destinazione turistica.
Il modello è stato inoltre applicato per misurare la competitività di due destinazioni turistiche
leader in America Latina: Rio de Janeiro e Salvador de Bahia. Nonostante il Brasile ospiterà la
Coppa del Mondo di Calcio del 2014 e i Giochi Olimpici del 2016, la competitività delle sue
destinazioni turistiche non è ancora stata adeguatamente studiata. E’ stata quindi realizzata una
survey presso esperti di turismo locali, alla quale hanno risposto 277 individui a Rio de Janeiro e
164 a Salvador de Bahia. I risultati forniscono ai policy maker e agli stakeholder locali un nucleo
di dati e informazioni ampio e accurato su cui basare le loro future strategie di destination
management.Competitiveness has been identified in the tourism literature as a critical factor for the success of tourism destinations. Many studies focus on the main factors affecting destination competitiveness. Nevertheless, there is still no evidence of a significant impact of these factors on the performance of a destination. This study aims at filling this gap, by adapting and extending the Richie & Crouch’s model and applying it on a unique dataset of 610 small and medium Italian Destinations of Excellence. To reduce the large set of variables, a principal component analysis (PCA) has been performed. The dependency between the performance scores and the explanatory variables has been then analysed by an ordinary least square and a partial least square regression. The empirical findings show that a sustainable tourism policy and destination management is not only good for preserving the ecologic balance and for minimize negative cultural and social impacts, but has a great importance for improving the competitiveness of a tourism destination. The model has also been applied to measure the competitiveness of two leading tourism destination in Latin America: Rio de Janeiro and Salvador de Bahia. Despite Brazil will host both the FIFA World Cup 2014 and the Olympic Games 2016, the competitiveness of its tourism destinations is still not adequately studied. Primary quantitative data were collected through experts’ judgement: 277 usable responses were received in the case of Rio de Janeiro, 164 in the case of Salvador. The evidences provide tourism policy makers and stakeholders with a valuable and accurate body of data on which to base their future destination management strategies.
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Perondi, Leonel Fernando. "Theoretical studies of diffusion in disordered systems." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334896.
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Allen, Robin William. "Topics in non-linear sigma models and string theory." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.232940.
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Dalley, Simon. "Matrix models and non-perturbative two-dimensional quantum gravity." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357132.
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Frankel, Jay Irwin. "A theoretical investigation of thermal waves." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/76212.
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A unified and systematic study of one-dimensional heat conduction based on thermal relaxation is presented. Thermal relaxation is introduced through the constitutive equation (modified Fourier's law) which relates this heat flux and temperature. The resulting temperature and flux field equations become hyperbolic rather than the usual classical parabolic equations encountered in heat conduction. In this formulation, heat propagates at a finite speed and removes one of the anomalies associated to parabolic heat conduction, i.e., heat propagating at an infinite speed. In situations involving very short times, high heat fluxes, and cryogenic temperatures, a more exact constitutive relation must be introduced to preserve a finite speed to a thermal disturbance.
The general one-dimensional temperature and flux formulations for the three standard orthogonal coordinate systems are presented. The general solution, in the temperature domain, is developed by the finite integral transform technique. The basic physics and mathematics are demonstrated by reviewing Taitel's problem. Then attention is turned to the effects of radially dependent systems, such as the case of a cylinder and sphere. Various thermal disturbances are studied showing the unusual physics associated with dissipative wave equations. The flux formulation is shown to be a viable alternative domain to develop the flux distribution. Once the flux distribution has been established, the temperature distribution may be obtained through the conservation of energy.
Linear one-dimensional composite regions are then investigated in detail. The general temperature and flux formulations are developed for the three standard orthogonal coordinate systems. The general solution for the flux and temperature distributions are obtained in the flux domain using a generalized integral transform technique. Additional features associated with hyperbolic heat conduction are displayed through examples with various thermal disturbances.
A generalized expression for temperature dependent thermal conductivity is introduced and incorporated into the one-dimensional hyperbolic heat equation. An approximate analytical solution is obtained and compared with a standard numerical method.
Finally, recommendations for future analytical and experimental investigations are suggested.Ph. D.