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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.
31

Modeling and Control of Voltage-Controlling Converters for Enhanced Operation of Multi-Source Power Systems

Cvetkovic, Igor 14 November 2018 (has links)
The unconventional improvements in the power electronics field have been the primary reason for massive deployment of renewable energy sources in the electrical power grid over the past several decades. This needed trend, together with the increasing penetration of micro-, and nano- grids, is bringing significant improvements in system controllability, performance, and energy availability, but is fundamentally changing the nature of electronically-interfaced sources and loads, altering their conventionally mild aggregate dynamics, and inflicting low- and high- frequency dynamic interactions that never before existed at this magnitude. This problem is not restricted only to the grid; modern electronic power distribution systems built for airplanes, ships, electric vehicles, data-centers, and homes, comprise dozens, even hundreds of power electronics converters, produced by different manufacturers, who provide very limited details on converters' dynamic behavior - distinctiveness that has the highest impact on how two converters, or converter and a system interact. Consequently, substantial dispersion of power electronics into the future grid will significantly depend on engineers' capability to understand how to model and dynamically control power flow and subsystem interactions. It is therefore essential to continue developing innovative methods that allow easier system-level modeling, continuous monitoring of dynamic interactions, and advanced control concepts of power electronics converters and systems. The dissertation will start with a "black box" approach to modeling of three-phase power electronics converters, introducing a method to remove source and load dynamics from in-situ measured terminated frequency responses. It will be then shown how converter, itself, can perform an online stability assessment knowing its own unterminated dynamics, and being able to measure all terminal immittances. The dissertation will further advance into an approach to control power electronics converters based on the electro-mechanical duality with synchronous machines, and end with selected examples of system-level operation, where small-signal instability in multi-source power systems can be mitigated using this concept. / Ph. D. / The modern technological advancements and ever-increasing needs for a sustainable future silently demand a serious revision of the conventional practice in electricity production, distribution, and utilization. These technologies are already challenging the limits of the biggest and most complex system ever built by humankind - the electrical grid. One practical solution to this problem is much higher dispersion of electronic power conversion systems capable of decoupling dynamics between system sources, distribution, and loads, while improving system controllability, reliability, and efficiency. Such a trend is already happening, and there has been an increased immersion of power electronics converters in electric cars, ships, airplanes, and the grid, in an effort to replace their traditional thermal, mechanical, hydraulic, and pneumatic systems. The goals have been to reduce the size, weight, and operational costs while increasing efficiency and reliability. In all these applications, a majority of energy sources and loads are interfaced to the power system through power electronics converters ranging in power from few watts to hundreds of megawatts. However, massive dispersion of power electronics into the future grid will significantly depend on engineers’ capability to understand how to model and dynamically control power flow and subsystem interactions. It is important to continue researching innovative methods that allow easier system-level modeling, continuous monitoring of interactions, and advanced control concepts of power electronics converters and systems. This dissertation hence addresses modeling of power electronics converters using their behavioral models, and shows how these models can assist the stability assessment of the system converters operate in. Additionally, dissertation presents an alternative way to control power electronics converters to behave as synchronous machines, and how this concept can be used to mitigate some stability problems.
32

tapestry: towards a newer 'parchitecture, that which is 'pataphysical

Fendik, Erik 11 June 2018 (has links)
How do we design for a local community while respecting heritage and touching their hearts? We know through our minds and we understand through our hearts. Consciousness touches minds and experience touches hearts. Since phenomenology is the study of both consciousness and experience, this phenomenological architectural thesis is designed to touch both minds and hearts. Instead of replacement, we need embracement in order to root one's social identity. Only then we will elevate cultural heritage in any context, for example African. This thesis includes a case study of light followed by a 'pataphysical design proposal for Tapestry: a new library at Mzuzu University in Malawi. The library proposal is introduced through poems and visual information in the following sets: metaphysical, physical, 'pataphysical. Through the inquiry in haiku writing style, this poetry collection evaluates corners, windows, light, intensity, form. Not only we propose an exciting and unique library design, but we also discover that dignity is the key to unlocking the spirit of light in any project, regardless of its form. / Master of Architecture
33

Théorèmes de point fixe et principe variationnel d'Ekeland

Dazé, Caroline 02 1900 (has links)
Le principe de contraction de Banach, qui garantit l'existence d'un point fixe d'une contraction d'un espace métrique complet à valeur dans lui-même, est certainement le plus connu des théorèmes de point fixe. Dans plusieurs situations concrètes, nous sommes cependant amenés à considérer une contraction qui n'est définie que sur un sous-ensemble de cet espace. Afin de garantir l'existence d'un point fixe, nous verrons que d'autres hypothèses sont évidemment nécessaires. Le théorème de Caristi, qui garantit l'existence d'un point fixe d'une fonction d'un espace métrique complet à valeur dans lui-même et respectant une condition particulière sur d(x,f(x)), a plus tard été généralisé aux fonctions multivoques. Nous énoncerons des théorèmes de point fixe pour des fonctions multivoques définies sur un sous-ensemble d'un espace métrique grâce, entre autres, à l'introduction de notions de fonctions entrantes. Cette piste de recherche s'inscrit dans les travaux très récents de mathématiciens français et polonais. Nous avons obtenu des généralisations aux espaces de Fréchet et aux espaces de jauge de quelques théorèmes, dont les théorèmes de Caristi et le principe variationnel d'Ekeland. Nous avons également généralisé des théorèmes de point fixe pour des fonctions qui sont définies sur un sous-ensemble d'un espace de Fréchet ou de jauge. Pour ce faire, nous avons eu recours à de nouveaux types de contractions; les contractions sur les espaces de Fréchet introduites par Cain et Nashed [CaNa] en 1971 et les contractions généralisées sur les espaces de jauge introduites par Frigon [Fr] en 2000. / The Banach contraction principle, which certifies that a contraction of a complete metric space into itself has a fixed point, is for sure the most famous of all fixed point theorems. However, in many case, the contraction we consider is only defined on a subset of a complete metric space. Of course, to certify that such a contraction has a fixed point, we need to add some restrictions. The Caristi theorem, which certifies the existence of a fixed point of a function of a complete metric space into itself satisfying a particular condition on d(x,f(x)), was later generalized to multivalued functions. By introducing different types of inwardness assumptions, we will be able to state some fixed point theorems for multivalued functions defined on a subset of a metric space. This is related to the recent work of French and Polish mathematicians. We were able to generalize some theorems to Fréchet spaces and gauge spaces such as the Caristi theorems and the Ekeland variational principle. We were also able to generalize some fixed point theorems for functions that are only defined on a subset of a Fréchet space or a gauge space. To do so, we used new types of contractions; contractions on Fréchet spaces introduced by Cain and Nashed [CaNa] in 1971 and generalized contractions on gauge spaces introduced by Frigon [Fr] in 2000.
34

Implementación de Sistema Integrador de Comunicaciones de Voz y Datos para el Gobierno Regional de Lima - Utilizando Plataforma Cisco Unified Communications Manager 7.0

Farro Lazo, Jorge January 2010 (has links)
Technology nowadays is evolving at rates that surpass anything imagination could perceive and it certainly affects every public or private enterprise. Well, according to this topic, I’m suggesting the improvement of the communications network of the Regional Government of Lima based on an integrated data and voice platform which includes a Cisco Centralized IP Telephony solution, called Cisco Unified Communications Manager 7.0, that works as a main element in order to achieve meaningful and complete management of internal and external telephone calls within MPLS Networks. Regional Government of Lima has been chosen because of its importance related to the economic activities of the population and the support that could be brought by an institution which could make success and generate productivity about rapid administrative processes . The thesis is divided into distinct chapters that make up the context of the investigation which involves network planning and design as an iterative process, encompassing topological design, network realization, IT asset sourcing and operations planning. For this purpose, information about the old and non sophisticated network status was raised. Costs and more details such as hardware and software features and more ways to make this network work so much better, with all the resources at its disposal, will be found on this whole solution
35

Piety, Intimacy and Mobility : A Case Study of Charismatic Christianity in Present-day Stockholm

Moberg, Jessica January 2013 (has links)
Stockholm County is a post-industrial Swedish region characterized by high levels of mobility and technologization as well as ethnic and religious diversity. Among its religious minorities exist various strands of charismatic Christianity, some of which originate from the Pentecostal revival of the early 20th century and some of which belong to more recent movements. The aim of this ethnographic study is to examine how affiliates of the multicultural charismatic Christian congregation New Life Church practice religiosity within the context of their personal daily lives, within the framework of the general congregation and in terms of their involvements with other religious organizations in the area of Stockholm. Beginning with the assumption that the practice of contemporary religiosity and the development of a religious identity are part of an ongoing process of habituation, the study describes how practitioners cultivate a form of charismatic piety characterized by certain embodied orientations, patterns of ritualization and narrative genres. To shed further light on this process, it draws upon a variety of theories concerning ritualization, embodiment, performance, narratives and materiality. Apart from this, the study also constitutes an attempt to explore and measure the impact on the practitioners’ religiosity of late modern developments such as urbanization, detraditionalization and global mobility as well as the growing absorption in consumerism, emotional intimacy and the unfolding of the “authentic” inner self. While pursuing these ends, the study also calls into question previous assumptions about charismatic Christianity in Sweden, most particularly the assumption that today’s practitioners remain inclined to be entirely faithful to one given institution and its system of beliefs and practices. Indeed this view is directly challenged herein by the finding that contemporary charismatics are far more inclined to eclectically appropriate elements and models of thoughts from various contexts of origin as well as to affiliate with and/or visit multiple Christian institutions.
36

Théorèmes de point fixe et principe variationnel d'Ekeland

Dazé, Caroline 02 1900 (has links)
Le principe de contraction de Banach, qui garantit l'existence d'un point fixe d'une contraction d'un espace métrique complet à valeur dans lui-même, est certainement le plus connu des théorèmes de point fixe. Dans plusieurs situations concrètes, nous sommes cependant amenés à considérer une contraction qui n'est définie que sur un sous-ensemble de cet espace. Afin de garantir l'existence d'un point fixe, nous verrons que d'autres hypothèses sont évidemment nécessaires. Le théorème de Caristi, qui garantit l'existence d'un point fixe d'une fonction d'un espace métrique complet à valeur dans lui-même et respectant une condition particulière sur d(x,f(x)), a plus tard été généralisé aux fonctions multivoques. Nous énoncerons des théorèmes de point fixe pour des fonctions multivoques définies sur un sous-ensemble d'un espace métrique grâce, entre autres, à l'introduction de notions de fonctions entrantes. Cette piste de recherche s'inscrit dans les travaux très récents de mathématiciens français et polonais. Nous avons obtenu des généralisations aux espaces de Fréchet et aux espaces de jauge de quelques théorèmes, dont les théorèmes de Caristi et le principe variationnel d'Ekeland. Nous avons également généralisé des théorèmes de point fixe pour des fonctions qui sont définies sur un sous-ensemble d'un espace de Fréchet ou de jauge. Pour ce faire, nous avons eu recours à de nouveaux types de contractions; les contractions sur les espaces de Fréchet introduites par Cain et Nashed [CaNa] en 1971 et les contractions généralisées sur les espaces de jauge introduites par Frigon [Fr] en 2000. / The Banach contraction principle, which certifies that a contraction of a complete metric space into itself has a fixed point, is for sure the most famous of all fixed point theorems. However, in many case, the contraction we consider is only defined on a subset of a complete metric space. Of course, to certify that such a contraction has a fixed point, we need to add some restrictions. The Caristi theorem, which certifies the existence of a fixed point of a function of a complete metric space into itself satisfying a particular condition on d(x,f(x)), was later generalized to multivalued functions. By introducing different types of inwardness assumptions, we will be able to state some fixed point theorems for multivalued functions defined on a subset of a metric space. This is related to the recent work of French and Polish mathematicians. We were able to generalize some theorems to Fréchet spaces and gauge spaces such as the Caristi theorems and the Ekeland variational principle. We were also able to generalize some fixed point theorems for functions that are only defined on a subset of a Fréchet space or a gauge space. To do so, we used new types of contractions; contractions on Fréchet spaces introduced by Cain and Nashed [CaNa] in 1971 and generalized contractions on gauge spaces introduced by Frigon [Fr] in 2000.
37

Influencing consumer perceptions of a social issue: an experiment on the effects of credibility of the source, message sidedness and inward/outward focus on consumer attitudes toward genetically modified foods.

Renton, Michelle Susan January 2008 (has links)
This thesis aims to increase understanding of New Zealand consumer reactions to messages promoting genetically modified food products (GMFs) and to determine how the manipulation of three persuasion variables, message sidedness, source credibility and inward vs. outward focus impact upon consumer attitudes. To achieve this aim, the study integrated two frameworks, Bredahl's, (2001) determinants of attitudes towards GMFs and Wansink and Kim's, (2001) strategies for educating consumers about GMFs, into a new model. To empirically examine the model, a web-based experiment using a 2x2x2 between-subjects factorial design was conducted. The experiment exposed participants to one of eight treatment groups containing a promotional message for Genetically Modified foods. The participants then completed an on-line questionnaire detailing their responses to the messages. A total of 380 useable questionnaires were collected from a national sample of consumers and analysed using ANCOVA. The results of the study suggest that the outwardly focused, two-sided message was more powerful at lowering perceptions of risks, raising perceptions of benefits and positively influencing attitudes toward the ad than either the one-sided, outwardly focused message, or the inwardly focused messages of either sidedness condition. For purchase intentions individual differences appeared to be of greater influence than message factors.
38

社会へ働きかける医療ソーシャルワーカーの可能性 : マネジメント化による内向き姿勢を克服するために / シャカイ エ ハタラキ カケル イリョウ ソーシャル ワーカー ノ カノウセイ : マネジメントカ ニヨル ウチムキ シセイ オ コクフク スル タメ ニ

小畑 美穂, Miho Obata 20 March 2022 (has links)
近年の医療ソーシャルワークのマネジメント重視=内向き姿勢への疑問を呈し、(1)業務のマネジメント化への背景を探り、(2)歴史的資料の検討や医療従事者への質的調査を通し,それを克服する方途を探った。知見として,共感的対話,対象認識の重要性を得,①【業務を超えたつながり】が組織化への一歩,②【ソーシャルワーク経験・体験、覚悟】ができる環境と仕掛けづくり、③患者と【外来での継続的関わり】の三方法を示した. / Starting from the question of the recent management-oriented (inward-looking) attitude of medical social work, we explored (1) the background to the shift to management of work and (2) ways to overcome it through a review of historical data and qualitative surveys of medical professionals. The findings showed the importance of empathetic dialogue and recognition of the subject, and the three methods of 1) [connections beyond work] as a step toward organization, 2)creation of an environment and mechanism for [social work experience, and preparedness], then 3) [continuous involvement with patients in the outpatient setting]. / 博士(社会福祉学) / Doctor of Philosophy in Social Welfare / 同志社大学 / Doshisha University

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