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Etudes théoriques des transitions de phase dans des réseaux bidimensionnels périodiques de spinsAl Hajj, Mohamad 08 July 2005 (has links) (PDF)
Cette thèse présente des développements de méthodes applicables au traitement théorique de réseaux de spins périodiques. Une méthode (Self-Consistent Perturbation), est inspirée par une expansion perturbative de la fonction d'onde à partir d'une fonction de référence très localisée. Cette variante d'un formalisme Coupled Cluster conduit à des équations polynomiales couplées, aisément résolues. Les autres méthodes sont basées sur des changements d'échelle, dans l'esprit du Groupe de Renormalisation dans l'Espace Réel, le réseau étant vu comme des blocs en interaction. La théorie des Hamiltoniens effectifs, utilisant le spectre exact de dimères ou trimères de blocs, permet de définir des interactions effectives. On a considéré soit des blocs à nombre impair de sites, qu'on peut voir comme des quasi-spins, ce qui est susceptible de produire des réseaux isomorphes et permet, d'itérer le processus et de garder l'élégance et les concepts du formalisme du Groupe de Renormalisation, soit des blocs à nombre pair de sites, qui conduisent à une description excitonique renormalisée des états excités. Les méthodes ont été testées sur des réseaux simples, puis appliquées à la recherche de transitions de phase sur une série de réseaux bidimensionnels (carré anisotrope, 1/5-depleted, plaquette, Shastry-Sutherland) et à des rubans graphitiques. Les localisations des transitions de phase (et les valeurs des gaps) sont prédites de façon très cohérentes par les diverses méthodes utilisées et en bon accord avec les meilleurs évaluations disponibles. L'hypothèse de l'existence d'une phase intermédiaire dans le réseau Shastry-Sutherland est confortée par nos calculs.
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Matrix Quantum Mechanics And Integrable SystemsPehlivan, Yamac 01 July 2004 (has links) (PDF)
In this thesis we improve and extend an algebraic technique pioneered by M. Gaudin. The technique is based on an infinite dimensional Lie algebra and a related family of mutually commuting Hamiltonians. In order to find energy eigenvalues of such Hamiltonians one has to solve the equations of Bethe ansatz. However, in most cases analytical solutions are not available. In this study we examine a special case for which analytical solutions of Bethe ansatz equations are not needed. Instead, some special properties of these equations are utilized to evaluate the energy eigenvalues. We use this method to find exact expressions for the energy eigenvalues of a class of interacting boson models.
In addition to that, we also introduce a q-deformation of the algebra of Gaudin. This deformation leads us to another family of mutually commuting Hamiltonians which we diagonalize using algebraic Bethe ansatz technique. The motivation for this deformation comes from a relationship between Gaudin algebra and a spin extension of the integrable model of F. Calogero. Observing this relation, we then consider a well known periodic version of Calogero' / s model which is due to B. Sutherland. The search for a Gaudin-like algebraic structure which is in a similar relationship with the spin extension of Sutherland' / s model naturally leads to the above mentioned q-deformation of Gaudin algebra. The deformation parameter q and the periodicity d of the Sutherland model are related by the formula q=i{pi}/d.
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Composing biographies of four Australian women: feminism, motherhood and musicGraham, Jillian January 2009 (has links)
This thesis examines the impact of gender, feminism and motherhood on the careers of four Australian composers: Margaret Sutherland (1897–1984), Ann Carr-Boyd (b. 1938), Elena Kats-Chernin (b. 1957) and Katy Abbott (b. 1971). / Aspects of the biographies of each of these women are explored, and I situate their narratives within the cultural and musical contexts of their eras, in order to achieve heightened understanding of the ideologies and external influences that have contributed to their choices and experiences. Methodologies derived from feminist biography and oral history/ethnography underpin this study. Theorists who inform this work include Marcia Citron, Daphne de Marneffe, Sherna Gluck, Carolyn Heilbrun, Anne Manne, Ann Oakley, Alessandro Portelli, Adrienne Rich and Robert Stake, along with many others. / The demands traditionally placed on women through motherhood and domesticity have led to a lack of time and creative space being available to develop their careers. Thus they have faced significant challenges in gaining public recognition as serious composers. There is a need for biographical analysis of these women’s lives, in order to consider their experiences and the encumbrances they have faced through attempting to combine their creative and mothering roles. Previous scholarship has concentrated more on their compositions than on the women who created them, and the impact of private lives on public lives has not been considered worthy of consideration. / Three broad themes are investigated. First, the ways in which each composer’s family background, upbringing and education have impacted on their decision to enter the traditionally male field of composition are explored. The positive influence from family and other mentors, and opportunities for a sound musical education, are factors particularly necessary for aspiring female composers. I argue that all four women have benefited from upbringings in families where education and artistic endeavour have been valued highly. / The second theme concerns the extent to which the feminist movement has influenced the women’s lives as composers and mothers, and the levels of frustration, and/or satisfaction or pleasure each has felt in blending motherhood with composition. I contend that all four composers have led feminist lives in the sense that they have exercised agency and a sense of entitlement in choices regarding their domestic and work lives. The three living composers have reaped the benefits of second-wave feminism, but have eschewed complete engagement with its agenda, especially its repudiation of motherhood. They can more readily be identified with the currently evolving third wave of feminism, which advocates women’s freedom to choose how to balance the equally-valued roles of motherhood and the public world of work. I assert that Sutherland was a third-wave prototype, a position that was atypical of her era. / The third and final theme comprises an investigation of the ways in which historical and enduring negative attitudes towards women as musical creators have played out in the musical careers in these composers. It is contested that Sutherland experienced greater challenges than her successors in the areas of dissemination, composition for larger forces, and critical reception, but appears to have been more comfortable in promoting her work. The exploration of their careers demonstrates that all four of these creative mothers are well-respected and recognised composers. They are ‘third-wave’ women who have considerably enriched Australia’s musical landscape.
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Svobodné školy a jejich uplatnění v současném školství / Free schools and its application on contemporary educationBartošová, Alexandra January 2020 (has links)
I deal with the democratic school term in my diploma thesis. I clarify the term, I present few of the democratic schools and critical pedagogy. My goal is to highlight the qualities of the democratic school and demonstrate the arguments for considering it as equal and adequate to classical education system. I highlight the importance of attention and financial support from MŠMT for the democratic schools. Few of the democratic schools and the movements were inspired by the concept of independent british boarding Summerhill school and his founder Alexander Sutherland Neill. I will describe pedagogical principles of A. S. Nell and the history of Summerhill school in my thesis. Partial goals are to clarify in what extant and how were employed the principles of Summerhill school in schools in the Czech republic; and how can be the pedagogy of A. S. Neill followed in Czech settings. I will decribe my own point of view on the schooling and teaching. I will compare them to several schools, e.g. Scio school, Ježek bez klece school, Neškola, Sudbury Valley School, Neue Schule etc. after that. I will address the terms unschooling, democracy and boarding school. I employ a method of comparison, analogy, analisis and synthesis.
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Athletic Participation: A Test of Learning and Neutralization Theories.Hankerson, Mario Bernard 14 December 2002 (has links) (PDF)
Athletics has been regarded as a means of encouraging youth to build character, discipline, and develop healthy habits. However, literature has emerged that asserts athletics do not prevent deviant behaviors, but instead, influence one to commit deviant acts. As such, this research examined effects of athletics on the commission of deviant behaviors via learning and techniques of neutralization theories.
Subjects for this project included 325 college students from a southern regional university. Data were generated through the use of a self-report questionnaire, which measured variables pertaining to self-reported deviant behaviors including perceptions of peer deviance, neutralizing indicators, and sports participation.
The findings suggest some support for each theoretical model, differential association and techniques of neutralization. Both theoretical models were supported, in general, with learning theory having the most support. When participation in sporting activity was considered, however, the results consistently showed no effect on various types of self-reported deviant behavior.
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Finding Junctions in Spline-based Road GenerationNyström, Isak, Darwiche, Danny January 2022 (has links)
Splines are a common mixed-initiative technique for road generation. A designer draws the shape of the curve but the mesh can be procedurally generated along the spline. This relationship improves the workflow of building roads in virtual environments and video games without taking away all of the control of the designer. Whilst this technique is useful when building single roads such as race tracks, it unfortunately struggles when dealing with more complex road networks that feature intersections. These intersections struggle with overlapping meshes and flickering textures without a straightforward solution. This problem significantly limits the usefulness of spline tools when generating roads. This paper aims to solve part of this problem by suggesting a method for detecting intersections in splines that support procedural mesh generation.
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Investigation of soliton equations with integral operators and their dynamicsVikars Hall, Ruben, Svennerstedt, Carl January 2023 (has links)
We present Lax pairs and functions called Lax functions corresponding to Calogero- Moser-Sutherland (CMS) systems. We present the Benjamin-Ono (BO) equation and a pole ansatz to the BO equation, constructed from a specific type of Lax function called a special Lax function corresponding to Rational and Trigonometric CMS systems. We present a generalization of the BO equation called the non-chiral Intermediate wave (ncILW) equation and show that a family of solutions to the ncILW equation can be constructed from the special Lax function corresponding to the hyperbolic CMS system. We present the Szegö equation on the circle and the real line. We obtain a family of solutions to the Szegö equation on the real line using a pole ansatz. Using numerical methods, we display solution plots to the BO equation and Szegö equation.
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Understanding small infantry unit behaviour and cohesion : the case of the Scots Guards and the Argyll and Sutherland Highlanders (Princess Louise's) in Northern Ireland, 1971-1972Burke, Edward January 2016 (has links)
This is the first such study of Operation Banner: taking three Battalions as case studies, drawing upon extensive interviews with former soldiers, primary archival sources including unpublished diaries, this thesis closely examines soldiers' behaviour at the small infantry-unit level (Battalion downwards), including the leadership, cohesion, orientation and motivation that sustained, restrained and occasionally obstructed soldiers in Northern Ireland. It contends that there are aspects of wider scholarly literatures - from sociology, anthropology, criminology, and psychology - that can throw new light on our understanding of the British Army in Northern Ireland. The thesis will also contribute fresh insights and analysis of important events during the early years of Operation Banner, including the murders of two men in County Fermanagh, Michael Naan and Andrew Murray, and that of Warrenpoint hotel owner Edmund Woolsey in South Armagh in the autumn of 1972. The central argument of this thesis is that British Army small infantry units enjoyed considerable autonomy during the early years of Operation Banner and could behave in a vengeful, highly aggressive or benign and conciliatory way as their local commanders saw fit. The strain of civil-military relations at a senior level was replicated operationally â as soldiers came to resent the limitations of waging war in the UK. The unwillingness of the Army's senior leadership to thoroughly investigate and punish serious transgressions of standard operating procedures in Northern Ireland created uncertainty among soldiers over expected behaviour and desired outcomes. Mid-ranking officers and NCOs often played important roles in restraining soldiers in Northern Ireland. The degree of violence used in Northern was much less that that seen in the colonial wars fought since the end of World War II. But overly aggressive groups of soldiers could also be mistaken for high-functioning units â with negative consequences for the Army's overall strategy in Northern Ireland.
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Espaces dynamiques réduits en physique de la matière condensée :<br />Systèmes à effet Hall bicouches, réduction dimensionnelle et systèmes de spins magnétiquesMöller, Gunnar 21 September 2006 (has links) (PDF)
Pour la description des propriétés de basse température des systèmes en physique de la matière condensée, il est souvent utile de travailler avec un espace dynamique réduit. Cette philosophie s'applique aux systèmes bicouches à effet Hall quantique comme aux systèmes d'anyons et aux systèmes magnétiques frustrés qui représentent les exemples discutés dans cette thèse. <br /><br />On introduit une classe générale d'états appariés de fermions composites. Ces fonctions d'onde sont exploitées pour analyser l'état fondamental des systèmes bicouches à effet Hall au facteur de remplissage total un. A partir d'une étude de Monte Carlo variationnel nous concluons que la transition de phase compressible à incompressible observée dans ce système est du deuxième ordre. Nous étudions également la question de l'existence d'un état apparié à demi-remplissage dans les simples couches. Ensuite nous considérons des schémas de réduction dimensionnelle de systèmes bidimensionnels sur la sphère vers des systèmes unidimensionnels sur le cercle. Un tel mapping est établi pour des systèmes libres et un candidat pour un système d'anyons généralisé est proposé. Finalement, nous analysons les systèmes de spins magnétiques sur réseaux bidimensionnels et discutons si un état de glace de spins peut exister en présence d'interactions dipolaires à longue portée.
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A fundamental approximation in MATLAB of the efficiency of an automotive differential in transmitting rotational kinetic energyVaughn, James Roy 30 July 2012 (has links)
The VCOST budgeting tool uses a drive cycle simulator to improve fuel economy predictions for vehicle fleets. This drive cycle simulator needs to predict the efficiency of various components of the vehicle's powertrain including any differentials. Existing differential efficiency models either lack accuracy over the operating conditions considered or require too great an investment. A fundamental model for differential efficiency is a cost-effective solution for predicting the odd behaviors unique to a differential. The differential efficiency model itself combines the torque balance equation and the Navier-Stokes equations with models for gear pair, bearing, and seal efficiencies under a set of appropriate assumptions. Comparison of the model with existing data has shown that observable trends in differential efficiency are reproducible in some cases to within 10% of the accepted efficiency value over a range of torques and speeds that represents the operating conditions of the differential. Though the model is generally an improvement over existing curve fits, the potential exists for further improvement to the accuracy of the model. When the model performs correctly, it represents an immense savings over collecting data with comparable accuracy. / text
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