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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
641

Z Excursion : Spel-bidrag till Swedish Game Awards / Z Excursion : Game Entry for Swedish Game Awards

Nylin, Tobias January 2012 (has links)
This report describes my degree project. For my degree project I made a demo for a game idea that I've developed, and implemented for use with Xbox 360. The idea was about converting the feeling and gameplay of old 2D side-scrolling platform games into 3D, viewed from a first-person perspective. The Xbox 360 version of the demo was also submitted for the game competition Swedish Game Awards.  In the report, I explain this idea more extensive, what software I used to implement it, and how I implemented it. Finally, at the end I clarify the results and discuss fulfilled tasks and future improvements. I'm very pleased with my progress so far and I will continue to work on this on my own until it feels like a finished product that can be distributed. / Den här rapporten beskriver mitt examensarbete. För mitt examensarbete så gjorde jag en demoversion av en spelidé som jag utvecklat, och som implementerades för användning på Xbox 360. Idén bestod av att överföra känslan och spelmekaniken från gamla tvådimensionella sidoskrollande plattformsspel till 3D, sett ur ett förstapersonsperspektiv. Demoversionen för Xbox 360 skickades också in som ett bidrag till speltävlingen Swedish Game Awards.  I rapporten så förklarar jag idén mer utförligt, vad för mjukvara jag använde för att implementera den, och hur jag implementerade den. I slutet av rapporten så klargör jag resultaten och diskuterar mål som har uppfyllts samt idéer för att vidareutveckla spelet. Jag är nöjd med det jag åstadkommit hitintills och jag kommer att fortsätta arbeta på spelet själv tills det känns som en färdig produkt som kan distribueras.
642

Frottement saccadé dans les matériaux granulaire modèles / Characterisation of stick-slip in model granular materials

Hoang, Minh Tam 08 July 2011 (has links)
Cette étude a pour objectifs la caractérisation expérimentale des frottements saccadés dans les matériaux granulaires modèles constitués des billes de verre monodisperses en compression triaxiale drainée et l'identification des paramètres de contrôle. Cinq paramètres macroscopiques caractérisent ces frottements saccadés : la chute de déviateur et la contraction volumique, l'intermittence de déformation axiale, le module d'Young et le coefficient de Poisson. Les frottements saccadés affectent simultanément le déviateur et la déformation volumique. Le comportement macroscopique est globalement contractant tandis que le matériau tend vers un état limite critique en grandes déformations, à la manière des sables lâches. Cependant il présente localement, dans les phases de blocage qui suivent immédiatement les ruptures temporaires, le comportement dilatant des sables denses, qui obéit à une relation contrainte-dilatance linéaire et unique. Les frottements saccadés disparaissent au-delà d'une vitesse critique d'écrasement axial, qui dépend de la contrainte de confinement et de la taille des grains. Le module d'Young dynamique par propagation d'ondes varie avec la contrainte de confinement selon une loi de puissance. Le module d'Young quasi-élastique au départ des phases de blocage est constant à l'intérieur du domaine élastique, de même que le coefficient de Poisson. Le suivi par granulométrie laser et par analyse d'images des matériaux après un ou plusieurs essais triaxiaux permet de suivre l'évolution de la taille moyenne et de la forme des grains. Tandis que les instabilités par saccade disparaissent suite à un certain nombre d'essais, on observe, simultanément à une légère diminution du volume moyen, l'apparition progressive de populations d'objets non sphériques par une fusion des grains analogue au frittage. / The objectives of this study are the experimental characterisatino of the stick-slip instabilities in a model granular material and the identification of relevant control parameters. As monodisperse glass beads are subjected to drained triaxial compression tests, five macroscopic parameters characterize the stick-slip phenomenon: the deviator drop, the jump in volumetric contraction, the intermittence of the axial strain, Young’s modulus and Poisson’s ratio. The stick-slip events simultaneously affect the deviator stress and the volumetric strain. While the global material behavior is that of a loose sand, gradually contracting and hardening as it approaches its large strain critical state, its response in the “stick” phases immediately following the “slip” instabilities is similar to that of dense, dilatant sands, with a unique, linear stress-dilatancy relationship. Stick-slip events disappear beyond a critical axial strain rate, depending on the confining stress and on the grain diameter. The Young modulus associated to wave propagation varies with the confining stress according to a power law. The quasi-elastic modulus measured at the beginning of the stick phase is constant inside the elastic domain, as well as the Poisson ratio. The evolution of grain size and shape after one or several triaxial tests is monitored by laser granulometry and image analysis. The gradual vanishing of stick-slip events, on repeating the tests, is likely related to the global decreasing trend of average particle volume and to the formation of non-spherical objects, apparently by some phenomenon analogous to sintering.
643

Couches absorbantes hybrides multi-pas de temps en dynamique des sols / Multi-time step absorbing layers for soil dynamics problems

Zafati, Eliass 09 June 2015 (has links)
Ce travail de thèse qui a pour objet la génération et l'étude des couches absorbantes dans les problèmes impliquant la dynamique des sols, est divisé en trois parties essentielles. La première consiste à proposer une méthode de dimensionnement des couches absorbantes par l'amortissement de Rayleigh afin de simuler des problèmes de propagation d'ondes dans les milieux infinis. Cette méthode repose sur une analyse mathématique du problème de propagation d'ondes dans un milieu caractérisé par la matrice de Rayleigh, qui nous permet, d'une part, d'établir des conditions de minimisation des réflexions parasites aux interfaces, et d'autre part, de proposer une simple relation de dimensionnement du domaine absorbant basée sur la notion de décrément logarithmique. On se propose dans la deuxième partie d'appliquer une stratégie de couplage des schémas temporels pour des problèmes de propagation d'ondes dans les milieux infinis 1D et 2D. L'approche proposée est d'intégrer le domaine d'étude par un schéma explicite et le domaine absorbant par un schéma implicite, et d'évaluer le potentiel de cette méthode en faisant varier les rapports de pas de temps entre les sous domaines. Une attention particulière est accordée au cas 1D pour lequel l'effet de la finesse du maillage définie par le nombre d'éléments finis par longueur d'onde est également analysé. Par ailleurs, l'évolution du temps de calcul en fonction du rapport entre les pas de temps est étudiée afin d'estimer les gains réalisés par rapport à un calcul de référence où le problème global est intégré uniquement avec un schéma explicite. La dernière partie est dédiée à l'étude des couches amortissantes de type PML ("Perfectly Matched Layer") dans le cadre des couplages hybrides multi-pas de temps. Cette partie est introduite par une étude de stabilité des schémas temporels dans le cas d'une PML en 1D. La couche absorbante PML est intégrée selon un schéma implicite en adoptant des pas de temps plus importants que le domaine d'intérêt intégré selon un schéma explicite. Bien que cette méthodologie de couplage s'avère très efficace pour la reproduction des milieux infinis, les études paramétriques montrent une sensibilité à la taille du pas de temps plus forte que celle exhibée par les couches amortissantes de Rayleigh. / This thesis which deals with the study of absorbing layers for soil dynamics problems, is divided into three essential parts. The first part aims to propose a design method of absorbing layers by the Rayleigh damping to simulate wave propagation problems in infinite media. This method is based on a mathematical analysis of the wave propagation problem in a media characterized by a Rayleigh damping matrix, which allows us, firstly, to establish conditions for minimizing spurious waves at the interfaces, and another hand, to provide a simple design relationship for the absorbing domain based on the notion of the logarithmic decrement. The second part aims to apply the multi-time step strategy for wave propagation problems in 1D and 2D infinite media. The proposed approach is to integrate the physical domain by an explicit scheme and the absorbing domain by an implicit scheme and to evaluate the potential of this method by varying the time step ratio between subdomains. Special attention is given to the 1D case for which the effect of the mesh fineness, defined by the number of finite elements per wavelength, is also analyzed. Furthermore, the evolution of computing time depending on the time ratio is studied in order to estimate the gains made with respect to a reference computation achieved by a full explicit integration. The last part is dedicated to the study of the Perfectly Matched Layer (PML) as part of hybrid couplings multi-time step. This section is introduced by a stability study of temporal scheme for 1D cases. The absorbing layer PML is integrated by an implicit scheme with a time step larger than that of the domain of interest. Although this coupling methodology is very effective for the reproduction of infinite media, parametric studies show a sensitivity to the time ratio greater than that exhibited by the Rayleigh damping layers.
644

Aerodynamic Analysis of Conventional and Spherical Tires

Pakala, Akshay Kumar January 2020 (has links)
No description available.
645

AN EXAMINATION OF THE RELATIONSHIP BETWEEN PERSONALITY TYPE, SELF PERCEPTION ACCURACY AND TRANSFORMATIONAL LEADERSHIP PRACTICES OF FEMALE HOSPITAL LEADERS

Carroll, Gretchen Kay 10 November 2010 (has links)
No description available.
646

The analysis of Toeplitz operators, commutative Toeplitz algebras and applications to heat kernel constructions. / The analysis of Toeplitz operators, commutative Toeplitz algebras and applications to heat kernel constructions.

Issa, Hassan 19 June 2012 (has links)
No description available.
647

Dimensionseffekte in Halbleiternanodrähten / Dimensional Effects in Semiconductor Nanowires

Stichtenoth, Daniel 23 June 2008 (has links)
No description available.
648

Extension, Evaluation, and Validation of Load Based Testing for Residential and Commercial HVAC Equipment

Parveen Dhillon (14203079) 02 December 2022 (has links)
<p>With rising temperatures, urbanization, population growth, improving economic wellbeing, decarbonization and electrification efforts, the demand for space cooling and heating equipment is continuously increasing around the world. To counteract the effect of rising demand for air conditioners and heat pumps on total energy consumption, peak electricity demand, and emissions, it is crucial to promote the development and market penetration of energy-efficient systems. Establishing minimum energy performance standards (MEPS), energy labeling and utility programs are some of the effective and tested methods for achieving this goal. The technical basis for these energy efficiency standards is a testing and rating procedure for estimating equipment seasonal performance from laboratory tests. Although the current rating procedures provide standardized metrics to compare different equipment performances, they fail to appropriately characterize the field representative performance of systems by not considering the effects of: 1) test unit embedded controls, thermostat, and realistic interactions with the building load and dynamics; 2) different climate zones and building types; and 3) and other integrated accessories for improving energy efficiency such as economizer for rooftop units (RTUs). Therefore, current approaches for performance ratings neither incentives the development and implementation of improved system and control designs nor consumers with a metric that represents the advanced systems' actual energy savings. To address this, a load-based testing methodology that enables dynamic performance evaluation of equipment with its integrated controls, thermostat, and other accessories was recently proposed. The test methodology is based on the concept of emulating the response of a representative building conditioned by the test unit in a test lab using a virtual building model. </p> <p>In this work, the proposed load-based testing methodology was further extended, evaluated, and validated for residential heat pumps to integrate it into next-generation energy efficiency testing and rating procedures and to serve as a tool for engineers to develop and validate improved control algorithms in a laboratory setting. Further, a load-based testing method for evaluating the dynamic performance of RTUs with integrated economizers was also developed and demonstrated.</p> <p>A load-based testing approach previously developed for residential cooling equipment is extended for heat pump heating-mode and demonstrated for a variable-speed system. The heat pump's typical dynamic behaviors are captured along with controller imperfections that aren't reflected in current testing approaches. Further, a comprehensive comparison was performed between the proposed load-based testing approach to the current steady-state testing approach in the U.S., AHRI 210/240, based on performance evaluation of three residential variable-speed heat pumps to understand the differences and their significance for the next-generation rating procedure. For cooling mode, steady-state testing estimates higher seasonal performance, but for heating mode, the steady-state testing approach estimates higher seasonal performance for warmer climates and is comparable for colder climates. The load-based testing methodology was validated by comparing the laboratory performance of a heat pump to that of a residential building in a controlled environment. The virtual building modeling approach for building loads and thermal dynamics effectively captured these characteristics of the house. The heat pump's cycling rate response with run-time fraction, which represents the unit's overall dynamic response, matched well between lab load-based tests and house tests. The test unit's COP difference for cooling and heating tests was within 3% between the two facilities, except for 9% in 95°F and 6% in 104°F cooling dry-coil test intervals. To evaluate the applicability of the developed load-based testing methodology as next-generation rating standards, its repeatability and reproducibility were assessed based on multiple heat pump round-robin tests conducted in two labs. Overall, reasonable to good repeatability was observed in load-based test results in both labs, however, poor reproducibility was observed except for one heat pump heating mode results. A root cause analysis of the observed differences along with recommendations for a next-generation rating approach are presented. This work aided in the development of a CSA (Canadian Standards Association) standard EXP07:19 and its subsequent revision for equipment rating based on load-based testing.</p> <p>The application of the load-based testing methodology as a tool for the development and evaluation of a residential heat pump controller design was demonstrated. Further, a load-based testing methodology was developed and demonstrated for the dynamic performance evaluation of RTUs with integrated economizers in a test laboratory setting. Recommendations for future work to further develop and improve the repeatability, reproducibility, and representativeness of the load-based testing and rating approach for residential and commercial air conditioners and heat pumps are summarized at the end of the dissertation. </p>
649

Econometric Measures of Financial Risk in High Dimensions

Chen, Shi 09 January 2018 (has links)
Das moderne Finanzsystem ist komplex, dynamisch, hochdimensional und oftmals nicht stationär. All diese Faktoren stellen große Herausforderungen beim Messen des zugrundeliegenden Finanzrisikos dar, das speziell für Marktteilnehmer von oberster Priorität ist. Hochdimensionalität, die aus der ansteigenden Vielfalt an Finanzprodukten entsteht, ist ein wichtiges Thema für Ökonometriker. Ein Standardansatz, um mit hoher Dimensionalität umzugehen, ist es, Schlüsselvariablen auszuwählen und kleine Koeffizientenen auf null zu setzen, wie etwa Lasso. In der Finanzmarktanalyse kann eine solche geringe Annahme helfen, die führenden Risikofaktoren aus dem extrem großen Portfolio, das letztendlich das robuste Maß für finanzielles Risiko darstellt, hervorzuheben. In dieser Arbeit nutzen wir penalisierte Verfahren, um die ökonometrischen Maße für das finanzielle Risiko in hoher Dimension zu schätzen, sowohl mit nieder-, als auch hochfrequenten Daten. Mit Fokus auf dem Finanzmarkt, können wir das Risikonetzwerk des ganzen Systems konstruieren, das die Identifizierung individualspezifischen Risikos erlaubt. / Modern financial system is complex, dynamic, high-dimensional and often possibly non-stationary. All these factors pose great challenges in measuring the underlying financial risk, which is of top priority especially for market participants. High-dimensionality, which arises from the increasing variety of the financial products, is an important issue among econometricians. A standard approach dealing with high dimensionality is to select key variables and set small coefficient to zero, such as lasso. In financial market analysis, such sparsity assumption can help highlight the leading risk factors from the extremely large portfolio, which constitutes the robust measure for financial risk in the end. In this paper we use penalized techniques to estimate the econometric measures of financial risk in high dimensional, with both low-frequency and high-frequency data. With focus on financial market, we could construct the risk network of the whole system which allows for identification of individual-specific risk.
650

Structural and optical impact of transition metal implantation into zinc oxide single crystals and nanowires / Strukturelle und optische Auswirkungen derÜbergangsmetallimplantation in ZnO Einkristalle und Nanodrähte

Müller, Sven 30 March 2009 (has links)
No description available.

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