Дисертації: "History of electrical engineering"

1

Su, Sara Lee 1982. "Enhanced visual authoring using operation history." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/52805.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 117-123).
Graphical editors have introduced great flexibility to the designer's workflow, providing powerful digital tools and enabling the creation of complex and compelling designs. This thesis presents methods for improving these interactions by leveraging operation history. Much instrumentation and activity logging in software has been for the purpose of debugging, that is, for the benefit of the programmer or analyst. Our work addresses the mining of operation history for the benefit of the end user. We present three main contributions in this area. First, we introduce selection expansion, a method for facilitating the reuse of complex multiple-itemselections by identifying items that are likely to be edited together. We then discuss an extension of this work, soft grouping, which gives users more control than standard selection and more flexibility than standard grouping. Finally, we present an interactive visualization of operation history, interactive storyboards, which enables in-context browsing and manipulation of operation history. We demonstrate these approaches in the context of vector graphics editing and present the results of pilot studies using our software implementation. While this thesis focuses on the usage patterns of graphic designers, many of the strategies could be generalized to other domains.
by Sara Lee Su.
Ph.D.

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2

Owens, James Webster 1966. "Compression of synthetic aperture radar phase history data." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282500.

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Synthetic aperture radars (SARs) are modern airborne or spaceborne high-resolution imaging systems used in target imaging and terrain mapping applications. SAR systems collect large volumes of complex phase history data that, in some systems, is downlinked to predetermined ground receiving stations for storage and/or subsequent processing. Considering the volume of data generated, SAR phase history data compression techniques are naturally of interest. In this dissertation, three complete SAR phase history data compression systems are presented. Two compression systems are based on trellis coded quantization and can be used to compress phase history data collected by a SAR system, independent of the SAR's mode of operation. The third compression system employs an optimal rate allocation strategy. It is designed specifically for spotlight mode SAR systems and utilizes the fundamental result that a complex image can be formed from spotlight mode SAR phase history data using a (windowed) two-dimensional FFT. Performance evaluations are presented for these compression systems relative to other existing SAR phase history data compression systems.

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3

Kim, Taesoo Ph D. Massachusetts Institute of Technology. "Automatic intrusion recovery with system-wide history." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91107.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 67-71).
Compromises of our computer systems are inevitable. New software vulnerabilities are discovered and exploited daily, but even if the software is bug-free, administrators may inadvertently make mistakes in configuring permissions, or unaware users may click on buttons in application installers with little understanding of its consequences. Unfortunately, recovering from those inevitable compromises leads to days and weeks of wasted effort by users or system administrators, with no conclusive guarantee that all traces of the attack have been cleaned up. This dissertation presents RETRO, an automatic recovery system that repairs a computer after an adversary compromises it, by undoing the adversary's changes while preserving legitimate user actions, with minimal user involvement. During normal operation, RETRO records an action history graph to describe the system's execution, enabling RETRO to trace the adversary's changes and their effects. During repair, RETRO uses the action history graph to undo an unwanted action and its indirect effects by first rolling back its direct effects, and then re-executing legitimate actions that were influenced by that change. To minimize re-execution and user involvement, RETRO uses predicates to selectively re-execute only actions that were semantically affected by the adversary's changes, uses refinement to represent high level semantics into the action history graph, and uses compensating actions to handle external effects. An evaluation of a prototype of RETRO for Linux with 2 real-world attacks, 2 synthesized challenge attacks, and 6 attacks from previous work, shows that RETRO can handle a wide range of real attacks with minimal user involvement, and preserve user's changes by efficiently re-executing parts of an action history graph. These benefits come at the cost of 35-127% in execution time overhead and of 4-150 GB of log space per day, depending on the workload. For example, a HotCRP paper submission web site incurs 35% slowdown and generates 4 GB of logs per day under the workload from 30 minutes prior to the SOSP 2007 deadline. We believe those overheads are acceptable in systems whose integrity is critical in their operations.
by Taesoo Kim.
Ph. D.

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4

D'Ambrosio, Marco, and Marco Medaglia. "Vertical Axis Wind Turbines: History, Technology and Applications." Thesis, Halmstad University, Halmstad University, School of Business and Engineering (SET), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-4986.

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In this Master Thesis a review of different type of vertical axis wind turbines (VAWT) and a preliminary investigation of a new kind of VAWT are presented.

After an introduction about the historical background of wind power, the report deals with a more accurate analysis of the main type of VAWT, showing their characteristics and their operations. The aerodynamics of the wind turbines and a review of different type on generators that can be used to connect the wind mill to the electricity grid are reported as well.

Several statistics are also presented, in order to explain how the importance of the wind energy has grown up during the last decades and also to show that this development of the market of wind power creates new opportunity also for VAWT, that are less used than the horizontal axis wind turbine (HAWT).

In the end of 2009 a new kind of vertical axis wind turbine, a giromill 3 blades type, has been built in Falkenberg, by the Swedish company VerticalWind. The tower of this wind turbine is made by wood, in order to get a cheaper and more environment friendly structure, and a direct driven synchronous multipole with permanent magnents generator is located at its bottom. This 200 kW VAWT represents the intermediate step between the 12 kW prototype, built in collaboration with the Uppsala University, and the common Swedish commercial size of 2 MW, which is the goal of the company.

A preliminary investigation of the characteristics of this VAWT has been done, focusing in particular on the value of the frequency of resonance of the tower, an important value that must be never reached during the operative phase in order to avoid serious damage to all the structure, and on the power curve, used to evaluate the coefficient of power (Cp) of the turbine. The results of this investigation and the steps followed to get them are reported. Moreover a energy production analysis of the turbine has been done using WindPro, as well as a comparison with and older type on commercial VAWT.

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5

Basu, Anirban. "A reputation framework for behavioural history : developing and sharing reputations from behavioural history of network clients." Thesis, University of Sussex, 2010. http://sro.sussex.ac.uk/id/eprint/2458/.

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The open architecture of the Internet has enabled its massive growth and success by facilitating easy connectivity between hosts. At the same time, the Internet has also opened itself up to abuse, e.g. arising out of unsolicited communication, both intentional and unintentional. It remains an open question as to how best servers should protect themselves from malicious clients whilst offering good service to innocent clients. There has been research on behavioural profiling and reputation of clients, mostly at the network level and also for email as an application, to detect malicious clients. However, this area continues to pose open research challenges. This thesis is motivated by the need for a generalised framework capable of aiding efficient detection of malicious clients while being able to reward clients with behaviour profiles conforming to the acceptable use and other relevant policies. The main contribution of this thesis is a novel, generalised, context-aware, policy independent, privacy preserving framework for developing and sharing client reputation based on behavioural history. The framework, augmenting existing protocols, allows fitting in of policies at various stages, thus keeping itself open and flexible to implementation. Locally recorded behavioural history of clients with known identities are translated to client reputations, which are then shared globally. The reputations enable privacy for clients by not exposing the details of their behaviour during interactions with the servers. The local and globally shared reputations facilitate servers in selecting service levels, including restricting access to malicious clients. We present results and analyses of simulations, with synthetic data and some proposed example policies, of client-server interactions and of attacks on our model. Suggestions presented for possible future extensions are drawn from our experiences with simulation.

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6

Simons, Brad, and Brad Simons. "Set-Associative History-Aided Adaptive Replacement for On-Chip Caches." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/621128.

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Last Level Caches (LLCs) are critical to reducing processor stalls to off-chip memory and improving processing throughput, and replacement policy plays an important role in the performance of LLCs. Many replacement algorithms are designed to be thrash-resistant to protect the working set in the cache from scans, but a fundamental challenge is balancing thrash-resistance to changes to the working set over time as an application executes. In this thesis a novel Set-Associative History-Aided Adaptive Replacement Cache (SHARC) LLC replacement algorithm is proposed, which adjusts scan-resistance at run-time based on the current memory access properties of the application. This policy segregates the cache to protect the working set from scans and utilizes history information from recently evicted cache lines to increase or decrease amount of cache reserved for the working set. On average, SHARC improves IPC by approximately 11% over LRU replacement policy while only requiring 14% increase in overhead. The SHARC-NRU replacement policy is also proposed to reduce this overhead and achieves approximately 10% performance improvement and requires 11% less overhead than LRU.

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7

Manzi, Eric R. "SQL-ACT : content-based and history-aware input prediction for non-trivial SQL queries." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/119534.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 79-81).
This thesis presents SqlAct, a SQL auto-completion system that uses content-based and history-aware input prediction to assist in the process of composing non-trivial queries. By offering the most relevant suggestions to complete the partially typed query first at the word-level and then at the statement-level, SqlAct hopes to help both novice and expert SQL developers to increase their productivity. Two approaches are explored: word-level suggestions are optimized based on the database's schema and content statistics, and statement-level suggestions that rely on Long Short-term Memory (LSTM) Recurrent Neural Networks language models trained on historical queries. The word-level model is integrated in a responsive command-line interface database client which is evaluated quantitatively and qualitatively. Results shows SqlAct provides a highly-responsive interface that makes high quality suggestions to complete the currently typed query. Possible directions for integration with the word-level model in the command-line tool are explored as well as the planned evaluation techniques.
by Eric R. Manzi.
M. Eng.

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8

Christman, Jordan Louis. "Efficient Digital Spotlighting Phase History Re-Centering Hardware Implementation." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1480934083897465.

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9

Battaglin, Paulo David. "Contribuições sobre a gênese da Engenharia elétrica." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259122.

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Orientador: Gilmar Barreto
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Este trabalho mostra a evolução do conhecimento sobre a Eletricidade e suas aplicações, que com o passar dos séculos foram denominadas de Engenharia Elétrica. As contribuições desta pesquisa evidenciam os fatos principais que revelam os benefícios desta evolução para a sociedade humana, que tem aprendido a utilizar os fenômenos da Eletricidade na natureza. A Eletricidade está em estado latente na natureza e o seu potencial tem sido descoberto e desenvolvido pelos seres humanos através dos milênios. A sua utilização nos primórdios pelas civilizações antigas, o desenvolvimento do conhecimento sobre ela e suas aplicações elementares, bem como a descoberta da inter-relação integrada das várias formas de Eletricidade como a Eletrostática, a Corrente elétrica e o Eletromagnetismo constituem fundamentos da Engenharia Elétrica atual. A medição de grandezas elétricas é um processo fundamental na obtenção de conhecimento. Todavia, estamos apenas iniciando a compreensão deste processo que envolve a interface de medida, conforme explicita o resumo da história dos medidores elétricos a ser apresentada. A divulgação deste processo de acúmulo de conhecimento tem o objetivo de transmitir aspectos fundamentais sobre a Engenharia Elétrica na Universidade e na sociedade em geral
Abstract: This project presents the knowledge evolution concerning the Electricity and its applications, as well as it shows evidences they were called Electrical Engineering as time is up through the centuries. The collaboration of this research is the disclosure of some key realities that point out the evolution's benefits to human society, who has learnt through the applications of Electricity phenomena of nature Electricity has been latent in nature and human beings have discovered and developed its potential through millenniums. Electricity utilization by ancient civilizations in the beginnings, its knowledge development and its basic applications, the make into a whole interconnection among Electricity's shapes such as Electrostatics, Electrical current and Electromagnetism establish the existing Electrical Engineering's fundamentals. The measurement of electrical quantities is a key process for getting knowledge of them. However, we have just begun this process comprehension within a measurement interface, as it is presented ahead in electrical instruments history summary. The well endowed disclosure of this accumulated knowledge has a target to transmit key views on Electrical Engineering in University and to reach the local society
Mestrado
Automação
Mestre em Engenharia Elétrica

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10

Terry, Jason. "Incorporating mechanical, electrical and plumbing systems into historic preservation projects : three case studies." Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/803.

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11

Adamek, Anna. "Incorporating power and assimilating nature: Electric power generation and distribution in Ottawa, 1882--1905." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26435.

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The history of electric power generation and distribution in Ottawa reflects the city's political, economic, and environmental conditions. The process of electrification of the Canadian capital was shaped by strong personalities, by municipal, provincial and federal politics, and by the city's location on the Ottawa River, an interprovincial border. The idea of electrification was introduced by municipal politicians in 1880s as a way of redefining Ottawa as a 'power capital of the Dominion' rather than as the locus of the federal bureaucracy. Yet the process was soon dominated by three powerful Liberals---Thomas Ahearn, Erskine H. Bronson and Warren Y. Soper---who gained influence among the three social groups who constituted the majority of Ottawa residents, Irish Catholics English Protestants, and Methodists. Their strong political influence in the Canadian capital allowed the three industrialists to form alliances within the provincial and federal government to permit them to build an electric empire. By 1894, the year in which they created the Ottawa Electric Company and the Ottawa Electric Railway Company, Ahearn, Bronson and Soper held a monopoly over the city's power generation and distribution. Yet as the three entrepreneurs shaped the electric market and urban development of the city, their endeavours were influenced by the politics, location, and natural resources of the Ottawa area. The same factors that fashioned a strong monopoly, also obstructed it, leading to establishment of a municipal plant in 1905 and consequently creating an electric duopoly in Ottawa.

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12

Castro, Rosangela Nunes Almeida de. "A ENGENHARIA ELÉTRICA NA UNIVERSIDADE FEDERAL DE GOIÁS: reconstrução histórica do curso (1948 - 2012)." Pontifícia Universidade Católica de Goiás, 2013. http://localhost:8080/tede/handle/tede/699.

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This research analyzes the process of constitution and consolidation of the Electrical Engineering course of Universidade Federal de Goiás (UFG), as well as identify in this process the historical agents, laws and ideas that guided the organizational rules of the course. The hypothesis is that the Electrical Engineering course of UFG has three logical-historical moments: one that came up with the ideas of its creation (1948-1960), one of its foundation (1964-1985) and one that searched for the course s identity, its consolidation (1986-2012). This periodicity happens because of the historical, institutional and cognitive scenery. The transition from one logicalhistorical moment to another occurs because of the ruptures and continuities between the periods. In this way, based on a historical-sociological perspective, this work aims to search the logical-historical moments of the course, trying to uncover and interpret its current configuration. The inquiry way contemplates a bibliographical research, a documentary research and a field research. The bibliographical research happened during all the work and made it possible to verify the growing interest on engineering education . In the last eleven years there were done 53 thesis by engineers in postgraduate programs in education. The documentary research sought documents about the foundation meeting, of the council meetings, speeches, legislation, official gazette of the union, newspapers, curriculums, teachers dossiers, pictures and personal documents of the founders of the course. The field research used the oral history as methodology, to pick up the testimonial of the historical agents by opened interviews with the aim to solve disagreements and doubts about fates that occured all long the history of the course. The option for qualitative approach is justified because of its positive characteristics for the purposes of the study, such as the identification of important witnesses to determinant facts in the historical context of the electrical engineering course of UFG. The theoretical frameworks of this research are categories inherited from Bourdieu s sociological thought. Sociology is sought because the Electrical Engineering School is a social, scientific and educational institution, whose identity is based on principals, values, rules and organization forms that are given to it by agents that together wrote its history. The concepts of field, habitus and symbolical systems of Pierre Bourdieu substantiate the understanding of the Electrical Engineering School as a place of permanent fights and strategies of maintenance or subversion motivated by conscious or inconscious interest in obtaining vantages by owning the symbolical systems.
Esta pesquisa analisa o processo de constituição e consolidação do curso de Engenharia Elétrica da Universidade Federal de Goiás (UFG), bem como identifica nesse processo os agentes históricos, as leis e as ideias que orientavam as normas de organização do curso. Parte-se da hipótese que o curso de Engenharia Elétrica da UFG possui três momentos lógico-históricos: o das ideias de sua origem (1948-1960), o da fundação (1964-1985) e o da busca pela identidade do curso, ou seja, da consolidação (1986-2012). Esta periodicidade acontece em função do cenário histórico, institucional e cognitivo. A transição de cada momento lógico-histórico para o outro se dá em função das rupturas e permanências entre os períodos. Portanto, com base em uma perspectiva histórico-sociológica, objetiva-se perquirir os momentos lógico-históricos que constituíram o curso, buscando desvendar e interpretar a sua configuração atual. O modo de investigação contempla uma pesquisa bibliográfica, uma pesquisa documental e uma pesquisa de campo. O levantamento bibliográfico acompanhou todo o processo de pesquisa e possibilitou verificar o crescente interesse pelo tema ensino de engenharia . Nos últimos 11 anos foram defendidas 53 teses por engenheiros em programas de pós-graduação em educação. Na pesquisa documental para fundamentar esta tese, buscou-se a Ata da Assembleia de Fundação, as atas das reuniões de conselho, discursos, legislações, diário oficial da união, jornais, currículos, plataforma Lattes, dossiês dos professores, fotos e documentos pessoais dos fundadores do curso. Com relação à pesquisa de campo utilizou-se como metodologia a história oral para colher o depoimento dos agentes históricos, através de entrevistas abertas, com o objetivo de solucionar desacordos e dúvidas sobre fatos ocorridos ao longo da história do curso. A opção pela abordagem qualitativa deve-se às suas características favoráveis aos propósitos do estudo, como a identificação de testemunhas-chave para fatos determinantes no contexto histórico do curso de Engenharia Elétrica da UFG. Esta pesquisa tem como referencial teórico categorias herdadas do pensamento sociológico bourdieusiano. Os conceitos de campo, habitus, e sistemas simbólicos em Pierre Bourdieu fundamentam a compreensão da Escola de Engenharia Elétrica como um espaço de lutas permanentes e de estratégias de manutenção ou de subversão motivadas pelo interesse consciente ou inconsciente de obter os proveitos decorrentes da posse dos sistemas simbólicos.

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13

Roberts, Ivy. "Distant Electric Vision: Cultural Representations Of Television From “Edison’s Telephonoscope” To The Electronic Screen." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4720.

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Do inventions that exist only on paper have less credibility than functional technologies? How has the meaning and significance of audiovisual media and technology changed over time? This dissertation examines historiography and methodology for media history, arguing for an interdisciplinary approach. It addresses methodological issues in media history—media in transition, media archaeology, and film history—through an examination of television’s speculative era. It tackles moving-image history through an historical investigation of Victorian and Machine age “television”. Because the concept and terminology of “television” changed dramatically during this period, I use the phrases “distant electric vision” and “seeing by electricity,” to define the concept of electric and electronic moving-image technology. By identifying manifestations of “television” before functional models existed, this dissertation examines the ways in which a modern concept of moving-image technology came into existence. Engineers and inventors, as well as audiences and journalists contributed to the construction of “television.” Newspaper announcements, editorial columns, letters to the editor, rumors and satires circulated. Victorian-era readers, writers and inventors pictured “seeing by electricity” to do for the eye what the telephone had done for the ear, bringing people closer together though separated by great distances. In contrast, early twentieth-century Machine-age engineers placed more emphasis on systems, communication, design, and picture quality. Developments in the 1920s with complex systems and electronics made “distant electric vision” a reality. This dissertation identifies several shifts that took place during television’s speculative era from the Victorian “annihilation of space” to Machine-Age systems engineering. Journalists, readers, and engineers all play a part in the rhetoric of innovation. From the Victorian era to the Machine age, the educational function of popular science and the role of audiences in constructing meaning and value for new technologies remain relatively consistent. I offer several case studies, including Thomas Edison’s inventions, illuminating engineering, and Bell Labs experiments with television. This dissertation argues that modern television design relies on the ability of the technology to make an unnatural experience seem as effortless as possible. Ultimately, it advocates for an expanded definition of media and technology, along with an historical emphasis on context.

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Diniz, Renato de Oliveira. "A intervenção estatal no setor elétrico paulista: as grandes empresas e as grandes usinas - 1953/1997." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/8/8138/tde-25102011-090613/.

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A Criação da CESP em 1966 e de suas antecessoras (USELPA, CHERP, e CELUSA), foi um fator decisivo para o desenvolvimento do ramo da construção hidrelétrica na engenharia brasileira: o planejamento e implantação das usinas, sistemas de transmissão e redes de distribuição demandou um intenso esforço da estatal, das empresas projetistas e das construtoras das usinas. Esse esforço traduziu-se, além da implantação do parque gerador, constituído por grandes centrais hidrelétricas, integrado, entre si e o mercado consumidor, por um conjunto de extensas linhas de transmissão; produziu experiências e conhecimentos que ainda hoje destacam a engenharia hidrelétrica brasileira no contexto internacional. Possibilitou a implantação da indústria de equipamento elétrico pesado, ainda que sob domínio de empresas de capital internacional; e o forte crescimento da indústria de material elétrico leve: e capitalizou e capacitou empresas privadas de construção civil pesada, muitas delas hoje constituídas como fortes grupos empresarias nacionais em processo de internacionalização. O conhecimento produzido não se resumiu às questões de engenharia e construção. Ao herdar as obras e projetos em execução por suas antecessoras, o corpo técnico da CESP precisou desenvolver a percepção de que construir uma grande usina pressupõe uma série de necessidades que, podem parecer apenas de como desenvolver a maior capacidade possível de produzir quilowatts/hora a partir da construção de uma barragem e de uma casa de máquinas. Desenvolveu-se métodos de trabalho que também deram conta das dimensões sociais, culturais, econômicas e ambientais de modo abrangente e complexo. O projeto das usinas de Urubupungá (Jupiá e Ilha Solteira), construídas distantes dos centros de consumo para os quais deveriam fornecer energia, previu a criação de um polo de desenvolvimento na região em que se instalava, o estabelecimento de novas vias de comunicação entre o então estado de Mato Grosso e o oeste paulista, e o desenvolvimento de estudos dos impactos sobre a natureza das áreas alagadas e na vida das populações ribeirinhas afetadas.
The founding of CESP, in 1966, and of its predecessors (USELPA, CHERP, and CELUSA), was a decisive factor for the development of the area of hydroelectric plant construction in Brazilian engineering. The planning and implementation of the plants, transmission systems, and distribution networks demanded intense efforts on the part of the State-owned company, of the design firms, and of the builders of the plants. Those efforts resulted in, not only the implementation of the widespread energy generating system, consisting of large hydroelectric plants that are integrated among themselves and the consumer market by an extensive complex of transmission lines, but they produced experiences and knowledge that continue to highlight Brazilian electrical engineering on the international scene. It established the heavy electrical equipment industry, although under the aegis of companies backed by international capital, resulting in strong growth for the light electrical materials industry. It also brought capital and capacity to private heavy construction companies, many of which are strong national corporate groups that are in the process of becoming international. The knowledge that was produced is not limited to engineering and construction issues. Upon inheriting the works and projects of its predecessors, which were already underway, CESPs technical staff was forced to perceive that building a large plant presupposes a whole series of needs that might seem, at first, to be related only to how to develop the largest capacity possible for producing kilowatts/hour by building a dam and a machine hall. Working methods were developed that also handled the social, cultural, economic, and environmental dimensions in a broad a complex manner. The project of Urubupungás Jupiá and Ilha Solteira plants, which were built far from the consumer markets they were to supply with energy, provided for the creation of a development hub in the region where they were installed, the establishment of new means of communication between the then-State of Mato Grosso and western State of São Paulo, and the performance of studies regarding impacts on Nature in the flooded areas and on the lives of the river dwellers, who were affected.

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15

Holmgren, Lisa, and Isac Sanderberg. "SKYLTFÖNSTERS PÅVERKAN PÅ LJUS & RUM I HISTORISKA GATUMILJÖER." Thesis, Jönköping University, JTH, Byggnadsteknik och belysningsvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-53989.

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Syfte: Många aktörer har möjligheter att påverka hur gatans rum och ljusmiljö upplevs. Med möjligheten följer också ett ansvar att skapa en god och sammanhängande miljö som är lätt att röra sig i, inte minst på de platser där stadsrummet i sig är ett besöksmål. Målet med studien är således att öka kunskapsläget kring hur belysning i skyltfönster kan påverka gatans upplevda ljusmiljö och rumsuppfattningen samt att identifiera potentiella för- och nackdelar med belysta och släckta skyltfönster. Metod: I fallstudier utförda på plats i Stockholm samlades fysikaliska mätvärden in i form av luminansberäkningar och fältmätningar samt genom perceptiva analyser. För att undersöka upplevelsen utfördes tre analyser i kombination, Arne Branzells rumsanalys, Gordon Cullens ”Serial vision” och PERCIAL analys. Resultat: Skyltfönsterbelysning visade sig ha en påverkan på den upplevda ljusmiljön. Resultaten indikerar på att stora skyltfönster med jämn ljusnivå utan stora kontrastförhållanden förbättrade ljusmiljön. Likväl orsakade bländning en försämrad upplevd ljusmiljö. Helt släckta skyltfönster påverkade ljusmiljön negativt och rummet upplevdes även smalare. Vidare visar resultaten även att skyltfönsterbelysning ökar upplevd rumshöjd på motsatt sida av gatan då ljusnivån ökar. Konsekvenser: Studien resulterar i ett antal hypoteser om skyltfönsterbelysning i historiska gatumiljöer. Resultaten indikerar att skyltfönsterbelysning påverkar både rummet och ljusmiljöns upplevelse. Förmågan att orientera sig upplevdes bland annat bättre då skyltfönster var tända. Gatans upplevdes bredare vid tända skyltfönster respektive smalare vid nedsläckta. Storleken på skylfönster visades också vara en faktor i hur stor påverkan dess ljus hade på gatans ljusmiljö. Slutligen visar studien tydligt att bländning från skyltfönsterbelysning bör undvikas på grund av en negativ påverkan av individers uppfattning av miljön. Förbättrad kunskapsutveckling och samordning hos samtliga av stadens aktörer som belyser stadsrummet rekommenderas för att öka kvalitén den övergripande ljusmiljön för Västerlånggatan i Stockholm. Begränsningar: I studien har enbart ett område undersökts med ett antal unika egenskaper. Slutsatserna som dras är inte direkt generaliserbara för alla gatumiljöer. I stället har ett antal hypoteser presenterats som kan vara viktiga att ta hänsyn till vid belysningsplanering i miljöer där gatubelysning förekommer.

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16

Makhalas, Kharsan Al, and Faisal Alsehlli. "Wind Power." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-4336.

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This Bachelor thesis has been written at the Blekinge Institute of Technology. This thesis concentrates on the wind power and their components, also the large wind farm is studied. The electrical power is generated by using the power in wind to drive a wind turbine to produce mechanical power. This mechanical power can be converted into electrical power by using electrical induction generators. There are two types of the wind turbines, the horizontal axis and vertical axis wind turbine, where the horizontal axis wind turbine is mostly used and was studied in this thesis. The rotor can be placed in two directions: an upwind rotor where the blade of turbine faces to the wind, so it operates more smoothly and transmit more power. The other type is a downwind rotor which orients itself with respect for the wind direction. Moreover, the tower shadow makes the blade to flex, consequently resulting in fatigue, noise, and reduces output of the power. The modern wind turbine has been built with an odd number of blades which is important for the stability of the turbine. The rotor with an odd number of blades can be considered to be similar to a disc when calculating the dynamic properties of the machine. The main idea of this thesis is to study the wind power in general and large wind parks specifically. The Horns Rev wind park was taken as an example of a wind park in Denmark and the Gotland wind park as an example of a wind park in Sweden too. Into account, the distance between wind turbine in the wind direction cannot be too small. If the wind turbines are located to close to each other, the wind will be more and more turbulent after it passes through each single wind turbine. This would lead to that wind turbines downstream in the wind park, and it might even have to shut down due to that mechanical loading gets to high during strong conditions. This is due to the fact that when wind passes through the rotor of the wind turbine it gets very turbulent and the wind speed is decreased. The minimum length of the rotor should be approximately 5-7 rotor diameters to avoid that issue. Gotland Energy AB (GEAB) considered, that high voltage direct current light would be the only realistic way to solve the technical problems for the high amount of wind power in-feed. One result is that The stability of voltage during transient events, has become much better by using the high voltage direct current light so that the output current stability from the asynchronous generators have been improved, which reduces the stresses on the AC grid and on the mechanical construction of the windmills.
In general the wind turbines with three blades accommodated a thicker root are used. It is obvious that, the less number of blades on the wind turbine, the cost of material and manufacturing will be lower. It is worthy to mentioned that, the modern wind turbine has been built with an odd number of blades. When the length of the blade increases the deflection of blade tip due to axial wind force also increase as well. So without consider the increase in length of blade may lead to dangerous situation of collision of tower and blade. Moreover, by increasing the number of blades cost of the system would increased as well. The limit of transfer for the AC transmission system depends on the distance from shore and is therefore physically limited by this. AC large wind parks that are placed at a long distance from the shore, which means AC long transmission line, and more drop voltage A solution to AC long transmission line, it could be to decrease the offshore frequency and use a low frequency AC networks. There is a suggestion by for instance (Schütte, Gustavsson and Ström 2011). The usages of a low frequency system are in electrified railway systems, where the frequency ranges from 16.67 Hz to 25 Hz. However, the network of a low frequency would allow a simpler design of the offshore WTs and The aerodynamic rotor of a large WT operates at maximum revolutions at 15-20 rpm. The lower frequency would then allow a smaller gear ratio for turbines with a gearbox, or decrease the poles number for WTs with direct driven generators. This would lead to lighter and cheaper turbines. One of the disadvantages by using a low frequency system is the size of transformer would be increased, and hence, the costs of transformer will increased too. The operator of the grid, Gotland Energy AB (GEAB) considered, that HVDC light would be the only realistic way to solve the technical problems for the high amount of wind power in-feed. The experiences have supported expected improvements in the characteristics for example: - Stability in the system arose. - Reactive demands, power flows, as well as voltage level in the harmonic and system were reduced. - Flicker problems were eliminated with the installation of HVDC light and transient phenomena disappeared. Moreover, Overall experiences of Gotland Energy AB (GEAB) are that the control of power flow from the converters makes the AC grid easier to observe than a conventional AC network and the power variations do not stress the AC grid as much as in normal network. Voltage quality has been better with the increased wind power production. A topic to study in the future is the consequences of blackouts in power supply with many wind power farm.
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17

Fregonese, Lucio. "Volta's electrical programme." Thesis, University of Cambridge, 1999. https://www.repository.cam.ac.uk/handle/1810/272492.

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18

Shi, Bowen. "High performance permanent magnet electrical machine for electrical vehicle applications." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52331/.

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For electrical vehicle system, torque density, power density, output performance, high-speed range, reliability and cost are of the most importance. This means that the designing and manufacturing of high-performance traction system must be employed, regarding electrical machine, drive and battery. In this work, the main target is to propose and investigate methods for improving the designing of the electrical machine on EVs traction system. Permanent Magnet Synchronous Machine (PMSM) with the advantage on high power density, high efficiency and excellent power factor has been widely used in EVs applications, especially the high saliency type motor called Interior Permanent Magnet Machine (IPM). The use of performance map is a valuable evaluation tool for EVs machines, in terms of torque-speed ability and efficiency presentation. A FEM based performance mapping tool is designed and presented to improve such evaluation abilities, with motor control method evolved, advanced losses evaluation and optimal running time. With the evaluation tool secured, the design of an IPM traction motor is employed with prototype and experimental test, to deliver high power density, good torque performance, low harmonic content and wide speed capability. To ensure the smooth running of EVs, novel skewing method for motor, called modular skewing, is then introduced to archive optimal torque ripple minimization on IPM, rather than optimizing the cogging torque. The technique has been developed through vector redistribution algorithm and testified by 2D FEM modelling. Basing on the new designed IPM motor, a novel motor structure, named End-winding Flux Motor (EWFM), is invented, whose structure can be embedded to most type of conventional PMSM end-winding side for the purpose of end-winding utilization, power density increases and thermal improvements. In the end, the 3D FEM and experimental tests validate the concept of EWFM.

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19

Albrecht, Martin. "Enabling socio-technical transitions – electric vehicles and high voltage electricity grids as focal points of low emission futures." Licentiate thesis, KTH, Miljöstrategisk analys (fms), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-206973.

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Today humankind is facing numerous sustainability challenges that require us to question CO2 intensive practices like those present in the transport and energy sector. To meet those challenges, many countries have adopted ambitious climate targets. Achieving such targets requires an understanding of the wider socio-technical context of transitions. The aim of this licentiate thesis is therefore to analyse such socio-technical transitions towards low-emission futures enabled by the electrification of passenger cars and high voltage grid development. A combination of different transitions theories (for ex. Multi-level perspective and Technological innovation systems) and institutional theory has been used. To reach the aim paper I analyses the climate impacts of electric vehicles (EVs) and policy measures to achieve a breakthrough scenario for EVs. The results show that a mixture of short and long term policies are needed that take into account the technology development stage and behavioural aspects of EV adopters. Paper II addresses the need to include the high voltage transmission grid and its planning procedures as a central part of debates on transitions. Therefore the opportunities, challenges and reasons for conflict in the established regime are studied. The results show that in order to achieve a sustainable grid development regime, it is necessary to spend time on achieving legitimacy and social sustainability. The third paper uses semi-structured expert interviews and focuses on innovation dynamics for EV adoption. By focusing on dynamics instead of single policy measures, it is possible to grasp interactions within a niche, but also in between a niche, regime and landscape. The results show that strong initial technology legitimacy was needed to start substantial innovation dynamics. This could be further strengthened with a strong and broad coalition of actors. Both those factors led, if present, to an improved variety and match of policy instruments. As such this thesis has shown that transitions are not just about technology or policy instruments as such but about the dynamics and processes needed to enable them. This can be relevant in other transitions that otherwise may underestimate the importance of these components.

QC 20170512

Norstrat

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20

Chien, Yu-Chien. "Electrical Aspects of Impinging Flames." Thesis, University of California, Irvine, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3682710.

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This dissertation examines the use of electric fields as one mechanism for controlling combustion as flames are partially extinguished when impinging on nearby surfaces. Electrical aspects of flames, specifically, the production of chemi-ions in hydrocarbon flames and the use of convective flows driven by these ions, have been investigated in a wide range of applications in prior work but despite this fairly comprehensive effort to study electrical aspects of combustion, relatively little research has focused on electrical phenomena near flame extinguishment, nor for flames near impingement surfaces. Electrical impinging flames have complex properties under global influences of ion-driven winds and flow field disturbances from the impingement surface. Challenges of measurements when an electric field is applied in the system have limited an understanding of changes to the flame behavior and species concentrations caused by the field. This research initially characterizes the ability of high voltage power supplies to respond on sufficiently short time scales to permit real time electrical flame actuation. The study then characterizes the influence of an electric field on the impinging flame shape, ion current and flow field of the thermal plume associated with the flame. The more significant further examinations can be separated into two parts: 1) the potential for using electric fields to control the release of carbon monoxide (CO) from surface-impinging flames, and 2) an investigation of controlling electrically the heat transfer to a plate on which the flame impinges. Carbon monoxide (CO) results from the incomplete oxidation of hydrocarbon fuels and, while CO can be desirable in some syngas processes, it is usually a dangerous emission from forest fires, gas heaters, gas stoves, or furnaces where insufficient oxygen in the core reaction does not fully oxidize the fuel to carbon dioxide and water. Determining how carbon monoxide is released and how heat transfer from the flame to the plate can be controlled using the electric field are the two main goals of this research. Multiple diagnostic techniques are employed such as OH chemiluminescence to identify the reaction zone, OH PLIF to characterize the location of this radical species, CO released from the flame, IR imaging and OH PLIF thermometry to understand the surface and gas temperature distribution, respectively. The principal finding is that carbon monoxide release from an impinging diffusion flame results from the escape of carbon monoxide created on the fuel side of the flame along the boundary layer near the surface where it avoids oxidation by OH, which sits to the air side of the reaction sheet interface. In addition, the plate proximity to the flame has a stronger influence on the emission of toxic carbon monoxide than does the electric field strength. There is, however, a narrow region of burner to surface distance where the electric field is most effective. The results also show that heat transfer can be spatially concentrated effectively using an electric field driven ion wind, particularly at some burner to surface distances.

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21

Carnes, Mark T. "Conceptual understanding of threshold concepts of electrical phenomena| Mental models of senior undergraduates in electrical engineering." Thesis, Purdue University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10244516.

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Every field of study has a set of domain-specific concepts that anyone who desires to work in that field must know and understand. Most students who pursue university degrees in engineering trust that their education is designed to provide them with this knowledge. But does it? In electrical engineering (EE), conceptual understanding of electrical phenomena has rarely been addressed. Even though the presumed goal of instructors and students alike is to learn the concepts of electrical phenomena well enough to be able to use the concepts to design useful things, it is difficult to determine whether this goal is being achieved. The purpose of this study was to develop reasonable representations of the mental models used by senior EE students as they thought about and worked with electrical phenomena. Focusing on students’ mental models of threshold concepts in electrical phenomena can thus increase knowledge of students’ conceptual understanding, which can contribute to systematic research into pedagogical and assessment methods in this area of study, which forms one of the most basic and fundamental areas of knowledge needed by EE students.

Thus, the research question addressed by this study was:

What do senior EE students’ mental models of the fundamental electrical phenomena of voltage, current, and the relationship between them look like?

The theory of mental models claims that everyone organizes their understanding of the way the world works by constructing models in the mind by which they both explain phenomena that they observe, and make predictions about what is likely to occur in a given situation.

To observe the students’ mental models in operation, semi-structured interviews were used to engage the participants in a conversation concerning their knowledge and experience in applying electrical ideas. Using discourse analysis, a representation of each student’s mental model was created, consisting of a concept map and a short narrative. While the models were all different, analysis of them as a group led to the emergence of five dominant themes, or ways of thinking.

The findings of this study have implications for the course of study that these students are engaged in. How effective has it been in developing the conceptual understanding that they will need after they graduate? Knowledge of the outcomes of a course of study: the conceptual understanding of these students, the misconceptions present in their models, and the dominant themes that drive their models, can inform ongoing efforts in curriculum development.

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22

Chauhan, Shweta. "Hysteretic controlled DC-DC converters." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1418308376.

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23

Chen, Hui. "Distributed Sensor Fault Diagnosis for Automated Highway Systems." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1390227394.

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24

Lawyer, Cody A. "Impact of SAR Image Formation Quality on Target Separability." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1400783630.

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25

Sanderson, Josh. "Hierarchical Modulation Detection of Underwater Acoustic Communication Signals Through Maximum Likelihood Combining." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1410872323.

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26

Li, Shuo. "6 GHz RF CMOS Active Inductor Band Pass Filter Design and Process Variation Detection." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1420812588.

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27

Zhang, Xiaomeng. "Multi-finger MOSFET Low Noise Amplifier Performance Analysis." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1420814124.

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28

Li, Dong. "Mixed Signal Detection and Parameter Estimation based on Second-Order Cyclostationary Features." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1448386709.

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29

Compaleo, Joshua David. "Split Ring Resonator Design for Agricultural Based Applications." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1452981065.

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30

Buchenroth, Anthony. "Ambiguity-Based Classification of Phase Modulated Waveforms." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1453302765.

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31

Chen, Jian. "RF CMOS Band Pass Filters with Wide Tuning Frequency, Controllable Pass Band and High Stopband Rejection: Using Passive and Active Inductors." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1472300517.

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32

Kolker, Rachael E. "GNSS Receiver Testing and Algorithm Development." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1495063279434231.

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33

Patel, Rishit Navinbhai. "Implementation of High Speed and Low Power Radix-4 8*8 Booth Multiplier in CMOS 32nm Technology." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1495371138748713.

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34

Smith, Jared. "Improvement of Continuous Wave Radar Measurements in a Partially Controlled Environment." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1496094047730053.

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35

Kotti, Vivek. "Design of an 8-bit Successive Approximation Pipelined Analog to Digital Converter (SAP-ADC) in 90 nm CMOS." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1503596547020087.

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36

Namala, Praneeth. "A 13T Single-Ended Low Power SRAM Using Schmitt-Trigger and Write-Assist." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1504191949021882.

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37

Chunchu, Vinay Kumar. "Layout Implementation of A 10-Bit 1.2 GS/s Digital-to-Analog Converter In 90nm CMOS." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1515626468169571.

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38

Tandon, Nina. "Biomimetic electrical stimulation for cardiac tissue engineering." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38323.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.
Includes bibliographical references (leaves 66-69).
A major challenge of tissue engineering is directing cells to establish the physiological structure and function of the tissue being replaced. Electrical stimulation has been used to induce synchronous contractions of cultured cardiac constructs. The hypothesis adopted for this study is that functional cardiac constructs can be engineered by "mimicking" the conditions present during cardiac development, and in particular, electrical stimulation using supra-threshold signals. For this Master's Thesis research, I have compared the material properties and charge-transfer characteristics at the electrode-electrolyte interface of various biocompatible materials, including carbon, stainless steel, titanium and titanium nitride, for use as electrodes in a biomimetic system for cardiac tissue engineering. I have also designed and implemented an electrical stimulator which is capable of modulating several important parameters of electrical stimulation, including stimulus amplitude and frequency.
(cont.) In addition, I have built an experimental setup incorporating this electrical stimulator and used it for experiments with C2C12 mouse myoblast cells and neonatal rat cardiomyocytes. Lastly, I have analyzed cell morphology as well as functional performance of engineered tissue by assessing excitation thresholds and maximum capture rates.
by Nina Tandon.
S.M.

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39

Uudelepp, Oscar, Ellen Nordén, and Douglas Lowén. "Electric Bike : Independent Project in Electrical Engineering." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-353617.

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A group project has been made in which the goal was to build an electric bike. The main focus of the project was to build the surrounding control system of a BLDC motor. A complete BLDC hub motor was purchased. The wheel managed to spin forward but it was never implemented on a bike due to time constraints. This was a rewarding and educational project that can be replicated or improved for future students.

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40

Khrapach, Ivan. "Engineering the electrical properties of graphene materials." Thesis, University of Exeter, 2012. http://hdl.handle.net/10871/8168.

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In this thesis the properties of graphene and its few-layers are engineered to make them highly conductive. Two different approaches were implemented to achieve this goal. One approach was to increase the concentration of charge carriers by intercalation of acceptor FeCl3 molecules between graphene planes. This resulted in a highly conductive yet transparent material which can be useful for applications. Another approach was to increase the mobility of carriers by means of removing surface contamination in the current annealing process. Optimal annealing parameters were found and a reproducible cleaning method was suggested.

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41

Björklund, Marcus, and Eric Fjärstedt. "Active Stabilizer : Independent Project in Electrical Engineering." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-324765.

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42

Goel, Vishu. "Novel coating technologies for electrical steels." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/93813/.

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Power loss in transformer cores accounts for approximately 5% of the energy lost as heat. The loss could be reduced by improving the secondary recrystallization methods, grain orientation control, increasing the electrical resistivity of the steel, reducing the thickness of laminations, manipulating the domain structure and applying coatings. Coating grain oriented electrical steel (GOES) helps in reducing the loss by providing electrical resistance, improving the surface roughness and applying beneficial tensile stress. In this work a range of coatings were explored that can be economically applied on GOES to reduce power loss and magnetostriction in working transformers. Coatings were investigated using a range of coating processes including electroless plating, thermal evaporation physical vapour deposition and electron beam physical vapour deposition. The coatings were characterised using a range of processes including Single Strip Testing (SST), Magnetostriction measurement, Vibrating Sample Magnetometer (VSM), magnetic domain imaging, Optical microscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD), Surface profilometry, Atomic force microscopy and Raman spectroscopy. Co-Ni-P applied on GOES improved the magnetic properties by applying beneficial tensile stress which aligns the domains in the direction of magnetization and by improving the surface roughness which reduces the number of pinning sites on the surface of steel. The magnetostriction was improved due to the effect of beneficial tensile stress. Similarly Co-PCNT applied on GOES reduced the power loss by improving the surface roughness. CrN, CrAlN, TiAlN improved the power loss and magnetostriction as tensile stress was applied by the coatings which reduced the domain width and hence loss was reduced. The reduction in magnetostriction was due to the high value of Young’s modulus of the coatings as compared to GOES which did not allow the steel to expand under the influence of applied magnetic field. The ceramic coatings could be directly employed in the production line replacing the phosphate coating unit with the Chemical/Physical vapour deposition.

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43

Zhang, Yuxi Ph D. Massachusetts Institute of Technology. "Electrospun nanofibers with tunable electrical conductivity." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81690.

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Анотація:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 114-117).
Electrospinning is a convenient method to produce nanofibers with controlled diameters on the order of tens to hundreds of nanometers. The resulting nonwoven fiber mats are lightweight, highly porous, and have high specific surface areas around 1 to 100 m2/g. Combined with the high electrical conductivity of intrinsically conductive polymers, conductive electrospun fiber mats are promising for a variety of applications, such as multifunctional textiles, resistance-based sensors, flexible reversibly hydrophobic surfaces, organic photovoltaics, scaffolds for tissue engineering, and conductive substrates for surface functionalization and modification Intrinsically conductive polymers, such as polyaniline (PAni), however, are relatively hard to Intrinsically conductive polymers, such as polyaniline (PAni), however, are relatively hard to process compared to most other polymers. They have fairly rigid backbones due to the high aromaticity, and are usually available only in relatively low molecular weight forms, so that the elasticity of their solutions is insufficient for it to be electrospun directly into fibers. Considerable amount of recent work has been reported trying to make electrospun polymeric nanofibers with intrinsically conductive polymers or composites. However, a large fraction of the work only showed the morphology and did not characterize the actual performance of these fibers, nor did they test the variability of the fibers and mats from a wide range of processing conditions and resulting structures. Therefore, this thesis aims to make a comprehensive study of the electrical tunability of electrospun fibers with intrinsically conductive polymers and its composites, to establish a clear processing-structure-property relationship for these fibers and fiber mats, and to test the resultant fibers with the targeted applications such as gas sensing. We have first developed a reliable method to characterize fiber electrical conductivity using interdigitated electrodes (IDE) and high-impedance analyzers with contact-resistance corrections, and applied to electrospun conductive polymer nanofibers. This method was shown to be reliable and sensitive, as opposed to some of the other methods that have been reported in literature. Facing with the challenge of overcoming the relatively low elasticity of the conductive polymer solutions to achieve electrospinnability, we have fabricated electrospun fibers of PAni and poly(3,4-ethylenedioxythiophene) (PEDOT), blended with poly(ethylene oxide) (PEO) or poly(methyl methacrylate) (PMMA) over a range of compositions. Pure PAni (doped with (+)- camphor-i 0-sulfonic acid (HCSA)) fibers were successfully fabricated for the first time by co-axial electrospinning and subsequent removal of the PMMA shell by dissolution. This allowed for the pure electrospun PAni/HCSA fibers to be tested for electrical performances and its enhancement as well as gas sensing application. The conductivities of the PAni-blend fibers are found to increase exponentially with the weight percent of doped PAni in the fibers, to as high as 50 ± 30 S/cm for as-electrospun fibers of 100% PAni/HCSA. This fiber conductivity of the pure doped PAni fibers was found to increase to 130 ± 40 S/cm with increasing molecular orientation, achieved through solid state drawing. The experimental results thus support the idea that enhanced molecular alignment within electrospun fibers, both during the electrospinning process and subsequent post-treatment, contributes positively to increasing electrical conductivity of conductive polymers. Using a model that accounts for the effects of intrinsic fiber conductivity (including both composition and molecular orientation), mat porosity, and the fiber orientation distribution within the mat, calculated mat conductivities are obtained in quantitative agreement with the mat conductivities measured experimentally. This correlation, along with the reliable method of fiber conductivity measurement by IDE, presents a way to resolve some of the inconsistencies in the literature about reporting electrical conductivity values of electrospun fibers and fiber mats. Pure PAni fibers with different levels of doping were also fabricated by co-axial electrospinning and subsequent removal of the shell by dissolution, and shown to exhibit a large range of fiber electrical conductivities, increasing exponentially with increasing ratio of dopant to PAni. These fibers are found to be very effective nanoscale chemiresistive sensors for both ammonia and nitrogen dioxide gases, thanks to this large range of available electrical conductivities. Both sensitivity and response times are shown to be excellent, with response ratios up to 58 for doped PAni sensing of ammonia and up to more than 105 for nitrogen dioxide sensing by undoped PAni fibers. The characteristic times for the gas sensing are shown to be on the order of 1 to 2 minutes. We have also developed a generic time-dependent reaction-diffusion model that accounts for reaction kinetics, reaction equilibrium, and diffusivity parameters, and show that the model can be used to extract parameters from experimental results and used to predict and optimize the gas sensing of fibers under different constraints without the need to repeat experiments under different fiber and gas conditions.
by Yuxi Zhang.
Ph.D.

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44

Proctor, Laura L. (Laura Lynne) 1975. "Tissue electrical impedance determination via microneedles." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/89893.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.
MIT Institute Archives copy bound: p. 1-78, 81-82, 79-80, 83-101.
Vita.
Includes bibliographical references (p. 81-84).
by Laura L. Proctor.
S.M.

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45

Cho, Margaret H. (Margaret Hyunjoo) 1982. "Environmental constituents of Electrical Discharge Machining." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32827.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.
Includes bibliographical references (leaves 30-31).
Electrical Discharge Machining (EDM) is a non-traditional process that uses no mechanical forces to machine metals. It is extremely useful in machining hard materials. With the advantages EDM has to offer and its presence as a common and useable technique, along with the other machining processes available to the industrial world, there is an added strain on the environment. The scope of this thesis includes analyzing the various inputs into EDM and the resulting outputs into the environment. A simplified model is used to analyze the process. The main categories of flow scrutinized in the model are material flow and energy flow. The most hazardous effect to the environment is found in the resin interaction of the wire EDM process where depending on the type of material machined, there is a potential presence of hazardous materials. There are efforts to recycle all salvageable materials such as wire and metal wastes, but currently no accountability system exists as manufacturers are responsible for their actions.
by Margaret H. Cho.
S.B.

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46

Lanka, Avinash. "Electrical Characterization and Applications of Supercapacitors." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1472052551.

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47

Risemark, Eriksson Martin. "Environmental stress of electrical machine winding insulation." Thesis, Uppsala universitet, Elektricitetslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-326711.

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The conducting winding of an electrical machine is insulated in order to prevent any short circuits to occur within the machine. This insulation is during its lifetime exposed to several environmental stresses and therefore plays an important role in the life length of the machine. Accelerated stress tests are used to investigate what design and material is most suitable for a good endurance of a product. In this master thesis, new accelerated test methods for the insulation system in an electrical machine are developed and evaluated. The study resulted in four stress tests that simulate the thermal stress, the thermomechanical stress and the ambient stress from direct oil cooling. Three diagnosis tests and a material analysis were used in order to evaluate how these accelerated stress test methods affected the insulation. The diagnosis tests showed no clear sign of deterioration of the insulation in terms of change in electrical characteristics. However, the material analysis indicated deterioration of the insulation, such as cracks and oxidation of the material. These changes show that the test methods are capable to affect the insulation, but will need more time to cause a breakdown, since a stator of this kind is expected to have a very long life length. Therefore, in future work on this topic, these test methods should continue for a longer time and it would likely be interesting to look into other diagnosis tests.

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48

Berrie, Jeffery A. "Measurement of electrical parameters for planar materials /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487759436328874.

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49

Hierro, Adrian. "Electrical characterization of defects in n-GaN /." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488204276532651.

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50

Raja, Muneeb Masood. "Extended Kalman Filter and LQR controller design for quadrotor UAVs." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1496152489565477.

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Дисертації з теми "History of electrical engineering"

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