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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.
1

Generative models of similarity-based classification /

Cazzanti, Luca. January 2007 (has links)
Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 101-107).
2

Numerical investigation of liquid film dynamics and atomisation in jet engine fuel injectors

Bilger, Camille January 2018 (has links)
Today’s aerospace industry continues to exploit liquid hydrocarbon fossil fuels. Motivated by operational considerations, continued availability and cost, this is likely to be the case for many years, despite the obvious environmental concerns. The interplay of liquid atomisation, spray vaporisation and the combustion process are intricately linked. However, the physical process of fuel injection and its atomisation into tiny droplets prior to combustion remains poorly understood. Because atomisation governs the size of the fuel droplets, and therefore their subsequent evaporation rate, adjusting the injection sequence is of paramount importance and will have far-reaching repercussions on many aspects of the combustion process, for example pollutant formation. In the context of jet engines, kerosene is usually injected in its liquid form via an airblast-type fuel injector. A coflowing high-speed airstream destabilises the liquid fuel, which is thus sprayed into fine droplets into the combustion chamber. The prediction of this phenomenon for various operating conditions relevant to the aeronautical industry requires a deeper understanding of the mechanisms involved in the interaction of the two fluids. A key element in predicting the complex behaviour of spray formation and evolution in jet engines is accurate modelling of fuel atomisation. Atomisation represents one of the key challenges that remains to be undertaken to make predictive computational simulations possible. However, the inherent multi-physics and multi-scale nature of this process limits numerical investigations. Thanks to the steady progress in computer power and Computational Fluid Dynamics (CFD) methods, computational modelling of injection systems emerges as a promising tool that can drive the design of future devices. This research project sets out to investigate the atomisation process in detail, in particular in providing physical insight into the fundamental physics of the phenomenon, in conjunction with an analysis on wetting behaviours and liquid droplet tracking. High-fidelity numerical simulations are performed using a novel in-house state-of-the-art multiphase flow modelling capability, RCLSFoam. The performance of the numerical scheme is demonstrated on typical two-dimensional and three-dimensional benchmark test cases relevant to both multiphase flow modelling and atomisation, and validated against other computational methods. An informed and systematic qualitative assessment of the topological variations of the phase interface during primary atomisation of a liquid film is made through dynamical analysis, while investigating an extensive domain of operating conditions at ambient and aero-engine injection conditions relevant to industry. This analysis demonstrated the influence of shear-driven instabilities on the atomisation process. The shear stress and difference in inertia between liquid and gas are observed to play a significant role in the atomisation process. In addition, the key physical mechanisms and their competing effects have been mapped out in order to predict the evolution of the process according to the operating conditions of the injection system. The proposed cartography gathers four different atomisation mechanisms. In particular, for sufficiently high liquid injection speeds, three-dimensional wave modes were observed to co-exist (the “3-D wave mode” regime). For very low liquid flow rates, accumulated liquid at the atomising edge undergoes deformation by which droplets are generated (the “accumulation” regime). For an increasing gas injection speed and a fixed liquid velocity, the effects of surface tension were observed to result in the generation of streamwise ligaments only, which tend to pair up (the “ligament-merging” regime). Finally, “vortex action” is another observed mechanism by which the liquid film is fragmented. Overall, this research project culminated in (i) the study of dynamic wetting behaviours, with the implementation and validation against experimental data of the Kistler dynamic contact model; and (ii) the demonstration of an algorithm for droplet capture and subsequent post-processing analysis of the droplet characteristics.
3

Aspects of n-tuple character recognition for a blind reading aid

Nappey, John Anthony January 1977 (has links)
This thesis reports research conducted into a character recognition system suitable for use in a reading aid for the blind. A brief review of blind reading aids is given, showing the need for a device which is cheap, simple and effective. The structure of a proposed reading aid fulfilling these needs is outlined, with a list of the desired characteristics of each of its subsystems. The remainder of the thesis is concerned with research into just two of these subsystems: the input device and the character recognizer. A detailed review of pattern recognition by the n-tuple method is presented, followed by a description of the experimental techniques used in obtaining real data from a camera system, and in simulating various recognizer structures. The camera system and computer programs developed specifically for the research are described in detail. Several series of experiments are reported, concerned mainly with investigating problems associated directly with the blind reading aid, namely accommodation of multifont printed text and of the tracking errors inherent in data from a hand-held probe. A further series of experiments, aimed at improving the performance of the recognizer within fixed size constraints, i. e., optimisation, has a wider field of application. Finally suggestions are made as to how the recognizer might be implemented in a reading aid, using RAMs, ROMs, or PLAs as the main storage elements.
4

L'assistance médicale à la procréation en droit international privé comparé / Medically assisted reproduction in comparative private international law

Rokas, Konstantinos 29 November 2016 (has links)
L'assistance médicale bouleverse les données de la procréation humaine. La gestation pour autrui, la procréation médicalement assistée en faveur des couples de même sexe ou effectuée post mortem changent radicalement la conception de la filiation. La dimension transfrontalière du phénomène suscite des difficultés, notamment s'agissant de la reconnaissance de liens de filiation créés à l'étranger. L'étude des législations étrangères libérales ainsi que de la jurisprudence relative à la circulation des filiations révèle un certain recul de la règle de conflit en matière de filiation. La méthode de la reconnaissance ne semble pas non plus à même de faciliter considérablement la reconnaissance des liens de filiation établis à l'étranger. Néanmoins, la protection de la vie familiale constitue un fondement commun aux États européens en faveur de cette reconnaissance. La reconnaissance peut d'ailleurs être promue par l'adoption d'une règle matérielle de droit international privé et par le renforcement de la motivation dans la mise en œuvre du mécanisme de l'ordre public international. Un tel renforcement, combiné avec l'influence du droit européen sur la circulation du statut personnel permettrait de mieux satisfaire les objectifs de sécurité juridique et de prévisibilité. En définitive, la lutte contre les risques posés par une assistance médicale à la procréation à caractère international requiert l'adoption des règles matérielles aussi bien au niveau national qu'au niveau international et une meilleure coopération entre États-membres de l'Union européenne. / Medically assisted reproduction radically affects human reproduction. Surrogacy, artificial reproduction technologies for same-sex couples, or which take place post mortem, profoundly change our concept of parentage. The cross-border dimension of this phenomenon provokes difficulties especially with respect to the recognition of parentage relationships that have been established in countries that authorise the aforementioned techniques. The study foreign liberal legislation, as well as of the case law on the circulation of legal parent-child relationships indicates that the conflict-of-laws rules on parentage becomes less significant. The method of recognition does not seem either able to facilitate considerably the recognition of parentage bonds that have been established in a foreign country. Nonetheless, the protection of family life constitutes a legal basis common in European states that can be invoked in favour of such recognition. Such recognition can furthermore be promoted by adopting a private international law rule of substantive nature and by strengthening the reasoning behind the recourse to the public policy exception mechanism this reinforcement of the reasoning and the influence of European law on the circulation of personal status can promote legal certainty and foreseeability. Finally, efficient solutions to cater for the risks inherent in cross­border access to assisted reproduction necessitates the adoption of rules substantial nature both in national and in international level and a better cooperation among member states of the European Union.
5

Развитие теоретико-методических основ учета и анализа в сфере розничной торговли : магистерская диссертация / Development of theoretical and methodological foundations of accounting and analysis in the retail sector

Дубцова, В. Э., Dubtsova, V. Je. January 2019 (has links)
Управление организацией розничной торговли невозможно без постановки эффективной системы бухгалтерского учета, основанной на соблюдении правил ведения бухгалтерского учета, связанных с товарно-материальными операциями и установленных законодательными и нормативными актами. Особенности учета доходов и расходов в сфере розничной торговли, заключаются в применении кассового метода, что вызывает необходимость усиления контроля за движением денежных средств. Предложенные меры совершенствования учетной политики по мониторингу движения денежных средств и за финансовыми результатами с помощью онлайн-касс позволят повысить эффективность учетно-аналитической деятельности в области бухгалтерского и налогового учета. Проведен анализ значимости влияния внешних и внутренних факторов на стратегическое планирование торговых организаций, в результате которого выявлено, что наиболее существенное воздействие оказывает совокупность внешних факторов федерального и регионального уровня. На основании исследования предложен алгоритм оценки факторов внешней среды организации розничной торговли для целей стратегического планирования. Овладение современными методами и средствами стратегического анализа позволит вести эффективный торговый бизнес. / Management of the organization of retail trade is impossible without the establishment of an effective accounting system based on compliance with the rules of accounting related to commodity and material operations and established by legislative and regulatory acts. Features of accounting for income and expenses in the retail sector, are the use of the cash method, which necessitates greater control over the movement of funds. The proposed measures to improve the accounting policy for monitoring cash flows and financial results with the help of online cash registers will improve the efficiency of accounting and analytical activities in the field of accounting and tax accounting. The analysis of the importance of the influence of external and internal factors on the strategic planning of trade organizations, which revealed that the most significant impact has a set of external factors at the Federal and regional levels. Based on the study, an algorithm for assessing the factors of the external environment of the retail trade organization for the purposes of strategic planning is proposed. Mastering modern methods and means of strategic analysis will allow you to conduct an effective trading business.

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