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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.
41

Design and Implementation of a Novel Single-Phase Switched Reluctance Motor Drive System

Staley, Amanda Martin 22 August 2001 (has links)
Single phase switched reluctance machines (SRMs) have a special place in the emerging high-volume, low-cost and low-performance applications in appliances and also in high-speed low-power motor drives in various industrial applications. Single phase SRMs have a number of drawbacks: low power density as they have only 50% utilization of windings, lack of self-starting feature unless otherwise built in to the machine, most of the times with permanent magnets or sometimes with distinct and special machine rotor configurations or additional mechanisms. Many of these approaches are expensive or make the manufacturing process more difficult. In order to overcome such disadvantages a method involving interpoles and windings is discussed in this research. Also, a new and novel converter topology requiring only a single switch and a single diode is realized. This research tests the concepts and feasibility of this new single-phase SRM motor topology and converter in one quadrant operation. The converter electronics and a simple minimum component, minimum cost analog converter are designed and implemented. The entire system is simulated and evaluated on its advantages and disadvantages. Simple testing without load is performed. This system has a large number of possibilities for development. Due to its lightweight, compact design and efficient, variable high-speed operation, the system might find many applications in pumps, fans, and drills. / Master of Science
42

Design and Implementation of Four-quadrant Operation in Single-Switch Based Switched Reluctance Motor Drive System

Park, Sung Yeul 27 July 2004 (has links)
In step with development of advanced, cost effective semiconductors and electrical motor drive components, the Switched Reluctance Machine (SRM) has become the center of public attention. Interest in a single-phase SRM has arisen in many places, especially because of its low cost applications. However, some drawbacks have plagued single-phase SRM: the lack of self-starting capability and restricted operation conditions. This thesis presents a four-quadrant operation SRM drive system with a single controllable switch for two phase configuration. The SRM's configuration has four main stator poles, four rotor poles, and four auxiliary stator poles. Because of this special arrangement, a four-quadrant operation with a given power converter topology and proposed control algorithms has been realized. The focus of the paper is to realize a four-quadrant operation with a single-switch converter based SRM. In addition, this research resulted in a new self-starting scheme without adding permanent magnets. Simulation results and experimental results utilizing the control algorithm verify the performance of the system. / Master of Science
43

Implications of Multiple Curve Construction in the Swedish Swap Market / Implikationer från Skapande av Multipla Kurvor på den Svenska Swapmarknaden

Lidholm, Erik, Nudel, Benjamin January 2014 (has links)
The global financial crisis of 2007 caused abrupt changes in the financial markets. Interest rates that were known to follow each other diverged. Furthermore, both regulation and an increased awareness of counterparty credit risks have fuelled a growth of collateralised contracts. As a consequence, pre-crisis swap pricing methods are no longer valid. In light of this, the purpose of this thesis is to apply a framework to the Swedish swap market that is able to consistently price interest rate and cross currency swaps in the presence of non-negligible cross currency basis spreads, and to investigate the pricing differences arising from the use and type of collat- eral. Through the implementation of a framework proposed by Fujii, Shimada and Takahashi (2010b), it is shown that the usage of collateral has a noticeable impact on the pricing. Ten year forward starting swaps are found to be priced at lower rates under collateral. Moreover, the results from pricing off-market swaps show that disregarding the impact of collateral would cause one to consistently underestimate the change in value of a contract, whether in or out of the money. The choice of collateral currency is also shown to matter, as pricing under SEK and USD as the collateral currencies yielded different results, in terms of constructed curves as well as in the pricing of spot starting, forward starting and off-market swaps. Based on the results from the pricing of off-market swaps, two scenarios are outlined that exemplify the importance of correct pricing methods when terminating and novating swaps. It is concluded that a market participant who fails to recognise the pricing implications from the usage and type of collateral could incur substantial losses. / Finanskrisens utbrott år 2007 orsakade abrupta förändringar i finansmarknaden. Räntor som tidigare följt varandra divergerade. Vidare gav både reglering av finansmarknaden och en ökad medvetenhet om motparters kreditrisk upphov till en tillväxt av kontrakt med ställda säkerheter. Följaktligen är det inte längre korrekt att prissätta swappar enligt metoder från tiden före finanskrisen. Mot bakgrund av detta är syftet med denna uppsats att applicera ett ramverk på den svenska swapmarknaden som på ett konsekvent sätt kan prissätta ränte- och valutaswappar med icke negligerbara räntespreadar, samt att undersöka prisskillnaderna som uppstår från användandet och typen av ställda säkerheter. Genom implementering av ett ramverk av Fujii, Shimada och Takahashi (2010b) visar denna studie att användandet av ställda säkerheter har en noterbar påverkan på prissättningen. Swappar med tio års löptider och framtida startdatum prissattes lägre när ställda säkerheter inkluderades i prissättningen. Vidare visar resultaten från prissättningen av off-market swappar att genom att bortse från effekten av ställda säkerheter så undervärderas ett kontrakts värdeförändring genomgående, oavsett om kontraktet är in the money eller out of the money. Valet av valuta på de ställda säkerheterna visade sig också spela roll, då prissättningen med SEK och USD som säkerhetsvalutor gav olika resultat i termer av konstruerade kurvor och i prissättning av spot-startande, framtida startande och off-market swappar. Baserat på resultaten ovan genererades två scenarion som påvisade vikten av en korrekt prissättningsmetod vid byte av motpart eller stängning av en swap. Härifrån dras slutsatsen att en marknadsaktör som inte inser vilken påverkan valet av ställda säkerheter har på prissättningen kan drabbas av betydande förluster.
44

Um olhar sobre a constituição dos saberes do trabalho dos leituristas de hidrômetros

Rodrigues, Ângela Beatriz Cavalli 29 March 2006 (has links)
Made available in DSpace on 2015-03-04T19:59:49Z (GMT). No. of bitstreams: 0 Previous issue date: 29 / Nenhuma / Esta dissertação é resultado de uma pesquisa de mestrado realizada no Programa de Pós-Graduação em Educação da Universidade do Vale do Rio dos Sinos - UNISINOS. A pesquisa situa-se no campo de estudos Trabalho e Educação e parte do entendimento de que o local de trabalho é um espaço educativo. Através de uma pesquisa qualitativa, investiga os saberes do trabalho de treze servidores públicos responsáveis pela leitura do consumo de água de uma capital brasileira, Porto Alegre. Para compreensão e análise dos dados pesquisados foi realizado um diálogo com autores que estudam a respeito da educação, do trabalho e dos saberes: Acácia Eneida Kuenzer, Bernard Charlot, Eloísa Helena Santos, Miguel Arroyo, entre outros. A pesquisa objetiva, desta forma, contribuir com os estudos que vêm sendo realizados acerca do saber prescrito e do saber real produzidos em situações de trabalho, olhando-os a partir do trabalho realizado na esfera pública / This paper is the result of a research undertaken for master degree certification. It was done at the Post Graduation Program on Education in the Universidade do Vale do Rio dos Sinos – UNISINOS. The research is set in the field of work and education studies and takes into account that the workplace is an educational place. Through a qualitative research, it investigates the workplace learning of thirteen public workers responsible for the water consume-reading of Capital of the Brazilian State of Rio Grande do Sul, Porto Alegre. For research data comprehension and analysis, a review of literature of some authors who have studied about education, knowledge and work was done; authors such as Acácia Eneida Kuenzer, Bernard Charlot, Eloísa Helena Santos and Miguel Arroyo, among others. Thus, this research aims to contribute with recent studies about prescript and real knowledge produced at the workplace, taking them from the public area starting-point
45

Ensaios de biodegradabilidade aeróbia para apoio à operação de contactor biológico rotatório tratando lixiviados / Aerobic biodegradability tests to support the operation of rotating biological contactor treating leachates

Soares, Carina Ines dos Santos 17 June 2013 (has links)
Submitted by Maicon Juliano Schmidt (maicons) on 2015-07-13T19:50:28Z No. of bitstreams: 1 Carina Ines dos Santos Soares.pdf: 7765458 bytes, checksum: dd167d7c7fa47d7d5c8180d36e705731 (MD5) / Made available in DSpace on 2015-07-13T19:50:28Z (GMT). No. of bitstreams: 1 Carina Ines dos Santos Soares.pdf: 7765458 bytes, checksum: dd167d7c7fa47d7d5c8180d36e705731 (MD5) Previous issue date: 2013-06-17 / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / FINEP - Financiadora de Estudos e Projetos / Ministério da Ciência e Tecnologia / te estudo teve como objetivo avaliar o potencial de biodegradação aeróbia de lixiviado de aterro sanitário e servir como apoio à operação de unidade piloto de tratamento biológico aeróbio, do tipo Contactor Biológico Rotatório (CBR), operado na Unisinos para tratamento de lixiviado gerado no Aterro Sanitário de São Leopoldo - RS. Esse sistema emerge como uma alternativa para o tratamento biológico de lixiviado de aterro sanitário, visto que fornece aos microorganismos as condições necessárias para a degradação de grande parte dos poluentes contidos neste tipo de efluente. Por meio de ensaios de biodegradabilidade aeróbia, utilizando o teste Zahn-Wellens, o potencial de biodegração aeróbia do lixiviado foi avaliado. A etapa de partida no CBR foi monitorada através de análises de parâmetros específicos (DQO e COT) e esses resultados foram comparados posteriormente com os resultados obtidos nos ensaios de biodegradabilidade aeróbia. O CBR foi operado de duas formas diferentes, variando-se a vazão e o tempo de retenção hidráulica do lixiviado no sistema. Na primeira forma de operação, a vazão utilizada foi de 8,5 L/h e tempo de retenção hidráulica de 15 h. Já a segunda forma de operação, a vazão utilizada foi de 5,1 L/h e tempo de retenção hidráulica de 24 horas. Os ensaios de biodegradabilidade revelaram potencial médio de biodegradação aeróbia do lixiviado, que alimentava o CBR, de 44,3% e 54,5% para os parâmetros de DQO e COT respectivamente. O final da etapa de partida ocorreu na segunda forma de operação, quando os percentuais médios atingidos de remoção no CBR chegaram a 15% e 18%, para os parâmetros de DQO e COT, respectivamente. / This study aims at evaluating the potential for aerobic bio-degradation of landfill leachate and being the support for the operation for the aerobic biological treatment pilot plant. This treatment is a Rotating Biological Contactor (RBC) kind, operated at Unisinos to process the leachate generated at the landfill located in São Leopoldo city - RS. This system has emerged as an alternative for the biological treatment of leachate, because it provides the necessary conditions for the micro-organisms to degrade most part of the pollutants contained in the effluent. The potential for aerobic bio-degradation of leachate was evaluated by testing for aerobic biodegradability using the Zahn-Wellens test. The starting period in RBC was monitored by the analysis of the specific parameters (COD and TOC) and then these results were compared to the results obtained in the tests for aerobic biodegradability. The RBC was operated in two different ways, varying the flow rate and the hydraulic retention time of the leachate system. In the first mode of operation, the flow used was 8.5 L/h and the hydraulic retention times (HRT) was 15 h. In the second mode of operation, the flow used was 5.1 L/h and the hydraulic retention time was 24 hours. The biodegradability tests showed that the average potential for the aerobic bio-degradation of the leachate used in RBC was 44.3% and 54.5% for COD and TOC parameters, respectively. The end of the starting period was in the second mode of operation when the average percentage of removal achieved in the RBC reached 15% and 18% for COD and TOC parameters, respectively.
46

Začínající učitel / Teacher the beginner

Lukášová, Jana January 2012 (has links)
My Diploma Thesis "Newly qualified teachers" is devoted to new teachers with less than 3 years of teaching experience after they graduated from accredited college and received a degree as a teacher. My focus is on the teachers in elementary schools. The goal of the theoretical part of my thesis is to collect technical information, opinions, ideas and knowledge from experts in the teaching profession in general, to characterize the new teacher's personality. In the few chapters I ponder possible fears, concerns, weaknesses and needs of the new teachers, and I also mention problematic field of the evaluation and self assessment of a new teacher. The content of the practical part of my thesis is exploratory inquiry using a method of survey. The goal of the questions and answers is to find out if the orientation of new teachers in elementary schools is functioning well with prepared orientation plan, and to identify and map out the problem areas that the new, inexperienced teachers feel in the beginning of their teaching carrier, and subsequently to detect and identify the new teachers' needs. I set preconditions for which I had the knowledge base from studying professional literature and from my many years of experience as an elementary school teacher. The topics of preconditions are: preparation for...
47

Podnikatelský projekt ve vybrané oblasti

KLÍMA, Petr January 2017 (has links)
Thesis: "Entrepreneurial Project in selected areas" processing business plan for a real business in an appropriate range. The theoretical part focuses on the general characteristics of a small company, its importance to the national economy and the terms and structure of the plan at its inception. The practical part deals with creating a business plan for a real project that will have a major operation to sell their products and services. Mapping the competition in the industry, customer structure, the financial aspects of the project, grant opportunities in business. The work ends with conclusions and recommendations that may in the future contribute to the establishment and development of the project.
48

Small wind turbine starting behaviour

Worasinchai, Supakit January 2012 (has links)
Small wind turbines that operate in low-wind environments are prone to suffer performance degradation as they often fail to accelerate to a steady, power-producing condition. The behaviour during this process is called “starting behaviour” and it is the subject of this present work. This thesis evaluates potential benefits that can be obtained from the improvement of starting behaviour, investigates, in particular, small wind turbine starting behaviour (both horizontal- and vertical-axis), and presents aerofoil performance characteristics (both steady and unsteady) needed for the analysis. All of the investigations were conducted using a new set of aerodynamic performance data of six aerofoils (NACA0012, SG6043, SD7062, DU06-W-200, S1223, and S1223B). All of the data were obtained at flow conditions that small wind turbine blades have to operate with during the startup - low Reynolds number (from 65000 to 150000), high angle of attack (through 360◦), and high reduced frequency (from 0.05 to 0.20). In order to obtain accurate aerodynamic data at high incidences, a series of CFD simulations were undertaken to illustrate effects of wall proximity and to determine test section sizes that offer minimum proximity effects. A study was carried out on the entire horizontal-axis wind turbine generation system to understand its starting characteristics and to estimate potential benefits of improved starting. Comparisons of three different blade configurations reveal that the use of mixed-aerofoil blades leads to a significant increase in starting capability. The improved starting capability effectively reduces the time that the turbine takes to reach its power-extraction period and, hence, an increase in overall energy yield. The increase can be as high as 40%. Investigations into H-Darriues turbine self-starting capability were made through the analogy between the aerofoil in Darrieus motion and flapping-wing flow mechanisms. The investigations reveal that the unsteadiness associated with the rotor is key to predicting its starting behaviour and the accurate prediction can be made when this transient aerofoil behaviour is correctly modelled. The investigations based upon the analogy also indicate that the unsteadiness can be exploited to promote the turbine ability to self-start. Aerodynamically, this exploitation is related to the rotor geometry itself.
49

Podnikatelský plán / Business Plan

Veselá, Jana January 2014 (has links)
Theme of my thesis is to create a business plan for establishing a limited liability company, which will deal with buying and selling animal feed, including presentation and processing of important aspects affecting the business of the undertaking, further assessments of its feasibility and usefulness. The theoretical part describes the possibilities and forms of business and content of business plan. In the practical part are elaborated the various steps required to establish a new company and its business plan. For purpose of processing individual analysis was used information from Czech and European institutions, market analysis, communication with selected suppliers and potential customers.
50

Podnikatelský plán / Business Plan

Marečková, Edita January 2014 (has links)
This thesis deals with the business plan. Intended business plan is to open a soup bar in a small French mountain town Chamonix Mont-Blanc. This business plan will serve primarily for internal purposes to identify the feasibility of the business idea. The thesis is divided into theoretical and practical part. The theoretical part first describes the typology of enterprises in France, then focuses on French tax system and social and health security system. The theoretical part also includes theory for processing the buiness plan, which is then applied in the practical part. The practical part deals with the specific business plan of the soup bar Le Nouveau Papillon. Important components of this business plan is a description of the business idea, analysis of the business environment and competition, financial plan and financial analysis, evaluating the effectiveness of investment and SWOT analysis.

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