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1
Hodge, Toni Ann. "Accreditation of Business Schools: An Explanatory Multiple-Case Study of their Motivations." Thesis, University of Canterbury. Management, 2010. http://hdl.handle.net/10092/3755.
Full textAbstract:
The commitment required of a university or business school to gain international
accreditation is significant, both in dollar terms and staff time. This thesis seeks to explain the motivations for business schools to seek accreditation with three major accrediting bodies, AACSB International, EFMD and AMBA, using a multiple-case study methodology underpinned by the frameworks of institutional isomorphism, bandwagon pressures and information asymmetry.
Interviews were carried out with 17 business school deans; five deans of accredited schools in Europe, five deans of accredited schools in the United States of America and seven
business school deans in New Zealand. All the New Zealand schools were either accredited, formally in the process of seeking accreditation or about to enter the application stage. The results provide supporting evidence for the notion that business schools are seeking
accreditation in order to achieve legitimacy benefits rather than performance benefits, and that intangible benefits are seen as having more importance than the costs involved with achieving accreditation. It was also found that where the focus is at an international level, accreditation is found to be underpinned by information asymmetries whereby schools are seeking to gain legitimacy by providing signals to the market regarding their quality. At a regional or national level information regarding quality is more well known and, instead, isomorphic and bandwagon pressures become evident as the pathway towards legitimacy. This study will be of value to business school deans in understanding the forces they are being subjected to when considering the value of seeking international accreditation. The results provide an understanding of why, in the absence of a formal business case, a school may consider such a move, or may have entered the process without the hard data that
identifies the costs and estimates the benefits in a measurable way. In this regard it will also be of value to all staff of business schools, and of the wider organisation, to understand the
phenomenon that is accreditation.
2
Dickinson, John C. "AFM, CAFM, and EFM Studies of the GaN System." VCU Scholars Compass, 2003. http://scholarscompass.vcu.edu/etd/4522.
Full textAbstract:
This thesis discusses a variety of techniques based on the atomic force microscope (AFM), and their application to the GaN materials system. In particular, the local conductivity and contact potential of surfaces have been measured using the techniques of Conductive AFM (CAFM) and Surface Potential Electric Force Microscopy (SPEFM), respectively. CAFM studies of GaN surfaces have revealed that prismatic planes around islands and pits on surfaces can lead to enhanced conductivity, which may be related to leakage problems in device applications. With regard to SP-EFM work, the change in surface potential associated with inversion domains on Ga-polar GaN has been imaged, yielding voltage differences up to 90 mV. Given that such inversion domains increase carrier scattering and can degrade device performance, their identification using this technique is important. SP-EFM has also been used to map the local surface potential in the active region of Modulation Doped Field Effect Transistors (MODFET's). This is the first step in a proposed study to investigate the effects of current lag in such devices.
3
Glassér, Charlotte. "Entreprenörskapets, Företagandets och det Innovativa tänkandets Läroplansdidaktik (EFID) i Gymnasieskolan : En fallstudie av Sveagymnasium." Thesis, Umeå universitet, Institutionen för tillämpad utbildningsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-135307.
Full textAbstract:
År 2010 fick Sverige en ny skollag för grund- och gymnasieskolan och år 2011 kom dess relaterade nya läroplaner. I styrdokumenten för gymnasieskolan formuleras och betonas starkt ”entreprenörskap, företagande och innovation”, som politiska utbildnings- och lärandemål, vilka ska genomsyra alla utbildningsår och ämnen. Syftet med denna studie är att bredda och fördjupa forskningen och kunskapen om hur läroplanen för gymnasiet 2011 transformerats och realiserats, vad avser utbildning och didaktiska praktiker i ”entreprenörskap, företagande och innovativt tänkande” (EFI Lgy 2011). Med en abduktiv, och hermeneutisk forskningsdesign och fallbeskrivning som metodansats kartläggs, analyseras och beskrivs hur skolledningen och kollegiet på den utvalda skolan ”Sveagymnasium”, och dess erbjudna treåriga högskoleförberedande utbildningsprogram, har transformerat och realiserat läroplanens direktiv om utbildning och lärande i EFI Lgy2011 under perioden 2012–2016. Studiens huvudsakliga bidrag är fallbeskrivningen av Entreprenörskapets, Företagandets och det Innovativa tänkandets läroplansdidaktik (EFID) på Sveagymnasium. Fallbeskrivningen förmedlar förståelsen av en skola där det föreligger formell och fastställd samordning mellan lärandemålen i entreprenörskap, företagande och innovativt tänkande (EFI Lgy 2011), relaterad schemabunden- och ämnesintegrerad undervisning, bedömning och betygssättning. Detta är den empiriska grunden för deninitierade teoribildningen och forskningen om Entreprenörskapets, Företagandets och det Innovativa tänkandets Didaktik (EFID Lgy 2011). Fallstudien kan även användas som pedagogiskt redskap i utbildande och skolutvecklande syfte. Studien avser främst att bidra till den empiriska, läroplansdidaktiska, forskningen och dess teoribildning med en sociokulturell och redskapsmedierad betraktelselins
4
Saborit, Rojas Enrique. "Update of a Externally Fired Micro Turbine (EFMT) for residential micro combined Heat and Power." Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118754.
Full text
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Barbosa, Maria Helena Neves. "Requalificação e gestão de ribeiras em áreas irrigadas mediterrânicas: aplicação ao perímetro de rega do EFMA." Doctoral thesis, ISA/UL, 2014. http://hdl.handle.net/10400.5/7346.
Full textAbstract:
Doutoramento em Restauro e Gestão Fluviais - Instituto Superior de Agronomia / Faculdade de Arquitectura / Instituto Superior TécnicoIn order to improve the drainage conditions of the several streams located in the Alqueva Multipurpose project, rehabilitation interventions (such as cleaning and reprofiling) are implemented. Little is known about the ecology of this streams, specially the analysis between these interventions' impact and vegetation recovery. Considering the legal requirements of Water Framework Directive, stream rehabilitation effects and overall effectiveness were assessed, and ecological deviations were analyzed between natural and agricultural streams (intervened and not intervened ones). Two types of streams were taken into account, small and large, so as to allow cause-effect relationships. To assess ecological functioning before and after interventions, and also to identify restoration standards between natural and agricultural streams, measurements expressed as categorized variables were performed, as well as statistical tests based on vegetation structure, riparian disturbance and morphological structure variables. The obtained results demonstrated that there are affections in both ecological structure and evolution after small stream reprofiling, as well as small deviations between not intervened and intervened streams and large deviations between agricultural and natural ones. Rehabilitation recommendations for future drainage regarding intervened streams are proposed.
6
Monteiro, Chrystel Nunes. "Evolução da paisagem de montado na área abrangida pelo EFMA: caso de estudo no concelho de Beja." Master's thesis, Universidade de Évora, 2016. http://hdl.handle.net/10174/19428.
Full textAbstract:
A construção da Barragem de Alqueva foi durante anos considerada como
fundamental no desenvolvimento da sustentabilidade e modernização da agricultura no
Alentejo.
Por outro lado a sua representação paisagística sempre se agregou a imagens de uma
agricultura de sequeiro e extensiva mas hoje estamos perante uma agricultura regada e
intensiva, tendo as alterações na agricultura levantado questões relativas à transformação da
paisagem desta região.
Na atual campanha de rega do Alqueva está previsto no sistema global de rega do
projeto um total de 120 mil hectares de regadio, no entanto já existem estudos que
possibilitam o aumento desta área, cerca de 45 mil hectares além do projeto inicial (EDIA,
acesso em 23-2-2016)
Desta forma pretende-se analisar a transformação da ocupação do solo, numa área
abrangida pelo EFMA, o concelho de Beja, de modo a perceber como essa transformação ao
longo do tempo tem incidido sobre a paisagem e afetado o Montado; EVOLUÇÃO DA PAISAGEM DE MONTADO NA ÁREA ABRANGIDA PELO EFMA
C a s o d e E s t u d o n o C o n c e l h o d e B e j a
A B S T R A C T:
The construction of the Alqueva Dam was fundamental to the sustainable
development and modernization of agriculture in the Alentejo.
On the other hand its landscape representation has always added an image of an
extensive and cutting agriculture but today we are facing a irrigated and intensive
agriculture, having as changes in agriculture raised questions related to the transformation of
the landscape of the region.
In the current irrigation campaign of Alqueva is planned for a total of 120 thousand
hectares of irrigation, there are no studies that allow the increase of the area, about 45
thousand hectares beyond the initial project (EDIA, access On 23-2-2016)
In this way we intend to analyze a transformation of the land occupation, in an area
covered by the EFMA, the Beja municipality, in order to understand how this transformation
over time has affected a landscape and affected the Montado.
7
Patrício, Marta Soraia Ribeiro. "A qualidade da água na Albufeira do Alvito e o empreendimento de fins múltiplos de Alqueva (EFMA)." Master's thesis, FCT - UNL, 2008. http://hdl.handle.net/10362/1943.
Full textAbstract:
Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de
Lisboa para obtenção do grau de Mestre em Engenharia do AmbienteO Empreendimento de Fins Múltiplos de Alqueva (EFMA) é um empreendimento que tem como objectivo principal a rega de cerca de 112 000 ha de terrenos que se distribuem entre as Bacias Hidrográficas do Guadiana e do Sado. A albufeira do Alvito integra-se no Subsistema de Rega Global de Alqueva sendo um dos reservatórios que receberá água provinda da albufeira do Alqueva. Esta albufeira será o principal centro distribuidor para todo o Baixo Alentejo. A presente dissertação pretende avaliar a influência da transferência da água do Alqueva na qualidade da água da albufeira do Alvito, com base no modelo matemático unidimensional Water Quality for River and Reservoir Systems. Para o cumprimento do objectivo proposto definiram-se dois cenários de simulação, com diferentes condições de exploração, um em regime natural e outro em regime de transferência de água. Os resultados obtidos por simulação permitiram identificar as principais alterações no sistema em termos de qualidade da água. No cômputo geral, os parâmetros simulados evidenciam uma degradação da qualidade da água após a adução de água proveniente da Bacia Hidrográfica do Guadiana. Atendendo às conclusões obtidas considera-se importante a formulação de estratégias que visem a mitigação dos potenciais efeitos decorrentes da transferência da água da Bacia Hidrográfica do Guadiana até à albufeira do Alvito.
8
Rezende, Angela Maria. "Eco-eficiência: um instrumento para enfrentar as exigência da Escrituração Fiscal Digital (EFD)." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/169628.
Full textAbstract:
Dissertação (mestrado profissional) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Ambiental, Florianópolis, 2015.Made available in DSpace on 2016-10-19T13:18:18Z (GMT). No. of bitstreams: 1 338950.pdf: 1976284 bytes, checksum: c23c73373158075c108c173b0e7d516e (MD5) Previous issue date: 2015
A Escrituração Fiscal Digital (EFD) é a nova obrigação tributária estabelecida no Brasil pela Secretaria da Fazenda, através do Sistema Público de Escrituração Digital (SPED), em que as empresas devem informar aos órgãos públicos todas as informações de estoques, movimentações e inventários relacionados à matéria prima e ao produto acabado, assim como apresentar a lista técnica de materiais (Bill of Material) a ser utilizada na produção dos produtos acabados. Isso abrange todas as operações de produção que influenciam na composição da base de cálculo e no valor devido do Imposto sobre a Renda da Pessoa Jurídica (IRPJ) e da Contribuição Social sobre o Lucro Líquido (CSLL). A iniciativa apresenta-se uma grande oportunidade para as empresas compartilharem com os Governos os indicadores de ecoeficiência, usando os mesmos recursos e processos das áreas de engenharia, produção, planejamento e controle e tecnologia de informação, necessários para atender às exigências tributárias. O presente estudo visa a elaborar uma proposta de classificação de risco ambiental e a designar indicadores para análise de desempenho ambiental no setor privado, com base no conceito de eco-eficiência e ecologia industrial. Estratégia usada para a geração de relatórios ambientais das empresas e divulgação aos órgãos governamentais, utilizando o mesmo fluxo de informação adotado nessa nova obrigação tributária.Tais informações possibilitam ao Estado exercer, na forma da lei, as funções de fiscalização, incentivo e planejamento de atividades, como intuito de garantir os interesses e o bem-estar das gerações presentes e futuras.
Abstract : Digital Tax Bookkeeping (EFD) is the new tax obligation established in Brazil, by the Ministry of Finance, through the public Digital Bookkeeping System (SPED), which companies must inform to the public agencies all inventory information, movements and inventories related to raw material and finished product, as well as presenting the bill of materials, to be used in the production of finished products. This means all production operations that influence the composition of the tax basis and the amount due to the Income Tax (IRPJ) and Social Contribution on Net Income (CSLL). The initiative presents a great opportunity for companies to share with governments the indicators of eco-efficiency, using the same resources and processes of engineering, production, planning and control and information technology, needed to meet the tax requirements.This study aims to develop a proposal for environmental risk assessment and designate indicators for analysis of environmental performance in the private sector, based on the concept of eco-efficiency and industrial ecology, to generate environmental reports of companies and disclosure to government agencies using the same flow of information adopted on this new tax obligation.This information enables the State to exercise, according to the law, the supervisory functions, encouragement and planning activities in order to ensure the interests and well-being of present and future generations.
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Desai, Vandana. "Aspects of community participation among slum dwellers in achieving housing in Bombay." Thesis, University of Oxford, 1992. http://ora.ox.ac.uk/objects/uuid:d4839cdd-effd-4ff2-975a-9a73c7b31d75.
Full textAbstract:
This thesis is concerned with the housing and service needs of the poor (slum dwellers) in Bombay and how they are articulated and satisfied. It discusses how the poor perceive the constraints on slum servicing and improvement, their involvement in community organizations, and the role the community and its leaders play in influencing state action. Since housing and servicing issues directly impinge on the interests of politicians and bureaucrats as well as on those of the poor, patterns of provision mirror closely the nature of the relationship between the poor and how political and administrative power operates at various levels. Chapter 1 provides the research aims and objectives while Chapter 2 reviews the literature on community participation. Chapter 3 on Bombay places housing development in context and also serves as background study to the thesis. This research studies three different slum settlements housing migrants to Bombay. Two surveys of these three slum settlements were carried out, involving interviews with 135 households. Chapter 4 describes the characteristics of these households, while chapters 5, 6, and 7 give the arguments of the thesis. It is shown that, despite an established system of representative community organisations and a pro-participation rhetoric in bureaucratic discourse, most slum dwellers are excluded from participating in decision-making. A patron-client relationship exists between politicians, bureaucrats and community leaders, both in determining the community leaders' power as well as the level of services and physical benefits that he/she could win for the slum community. Leaders are generally better educated, better employed, more prosperous and highly motivated than most of their community. The NGO in this study has acted mainly as intermediary between the government and the slum-dwellers.
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Silva, José Júnior Alves da. "Microscopia de força elétrica em amostra de óxido de grafeno." reponame:Repositório Institucional da UFC, 2013. http://www.repositorio.ufc.br/handle/riufc/8048.
Full textAbstract:
SILVA, José Júnior Alves da. Microscopia de força elétrica em amostra de óxido de grafeno. 2013. 100 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2013.Submitted by Edvander Pires (edvanderpires@gmail.com) on 2014-05-13T21:31:02Z No. of bitstreams: 1 2013_tese_jjasilva.pdf: 30925308 bytes, checksum: b2e1379686008553b3699b7736b7335b (MD5)
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Carbon-based structures have played a major role in scientific and technological fields. This is due to the versatility of the element carbon, the pillar of organic chemistry, which can form a variety of structures (about 10 million compounds), besides being a basic constituent of all known life forms. Depending on the conditions, this phenomenal element can occur in several allotropic forms: from an extremely brittle material, such as graphite, so incredibly resistant materials such as diamond, carbon nanotubes and graphene. These graphitic materials have been studied extensively, and present unique properties and great potential for technological applications. Among these materials, graphene currently occupies the most prominent position by having special electronic and mechanical properties. The graphene oxide is a class of graphitic structure consisting essentially of a graphene layer decorated with epoxide and hydroxyl groups on the surface and carboxyl and carbonyl groups on the edges. Its stoichiometry depends strongly on the method of production. In addition the graphene oxide is one of the main routes for obtaining large-scale graphene also it has several interesting properties, which allow, for example, biological applications, since their functional groups make it very reactive, besides being easily dispersed in water. Many issues related to graphene oxide are yet unclear, as also its structure, training procedure and mechanisms of interaction. Thus, the electric force microscopy (EFM) was used as the main tool to study electrostatic properties of a graphene oxide sample obtained by a modified Hummer method. By means of a simplified model, it was possible to develop a method for the analysis of the EFM measurements and so determine the presence and the sign of the net charge of the sample. Furthermore it is possible to clarify the origin of the edge phenomenon observed in EFM experiments.
As estruturas a base de carbono tem um papel de grande importância nos campos da ciência e da tecnologia. Isso graças à versatilidade do elemento carbono, pilar da química orgânica, que consegue formar uma diversidade de estruturas (cerca de 10 milhões de compostos), além de ser um constituinte básico de toda forma de vida conhecida. Dependendo das condições de formação, este fenomenal elemento, pode se apresentar em diversas formas alotrópicas: desde um material extremamente frágil, como o grafite, até materiais incrivelmente resistentes como o diamante, nanotubos de carbono e o grafeno. Esses materiais grafíticos têm sido extensivamente estudados, apresentando propriedades únicas e grande potencial em aplicações tecnológicas. Dentre eles, o grafeno ocupa, atualmente, a posição de maior destaque por possuir propriedades mecânicas e eletrônicas diferenciadas. O óxido de grafeno é uma classe de estruturas grafíticas constituída basicamente de uma camada de grafeno decorada com grupos epóxido e hidroxila na superfície e grupos carboxílicos e carbonila nas bordas. A sua estequiometria depende fortemente do método de obtenção. Esse material, além de ser uma das principais rotas para a obtenção em larga escala do grafeno, também apresenta diversas propriedades interessantes, que possibilitam, por exemplo, aplicações biológicas, uma vez que seus grupos funcionais o tornam bastante reativo além de ser facilmente dispersado em água. Muitas questões relacionadas ao óxido de grafeno ainda não estão bem esclarecidas, como sua própria estrutura, processo de formação e mecanismos de interação. Nesse sentido, foi utilizada, como principal ferramenta, a microscopia de força elétrica (EFM) para estudar propriedades eletrostáticas de uma amostra de óxido de grafeno obtida utilizando-se um método de Hummer modificado. Por meio de um modelo simplificado, foi possível desenvolver um método para análise das medições de EFM e assim determinar a presença e o sinal da carga líquida da amostra. Além de ser possível esclarecer a origem do fenómeno de borda observado nos experimentos de EFM.
11
O'Shea, Jacinta. "Human frontal eye fields and visual search." Thesis, University of Oxford, 2005. http://ora.ox.ac.uk/objects/uuid:42ba15a7-ef0d-4787-a313-bc54462bb831.
Full textAbstract:
This thesis tested whether the human frontal eye fields (FEFs) have visuospatial functions that are dissociable from FEF oculomotor functions. Functional magnetic resonance imaging (fMRI) was used to localize the FEFs, and transcranial magnetic stimulation (TMS) was applied in a series of experiments to transiently disrupt information processing in the FEFs. It was shown that TMS applied over the right FEFs degrades subjects' performance on a visual conjunction search task in which eye movements were not required and were not made. A TMS timing protocol subsequently showed that computations in the FEFs that occur between 40 and 80ms after the onset of a visual search array are critical for accurate performance. This suggests that, as in the monkey, the human FEFs may accumulate and use visual evidence from extrastriate cortex, which forms the basis for accurate visuospatial discrimination. A training protocol showed that the right FEFs are no longer critical for accurate visuospatial discrimination performance once a search task has been extensively practised. This study further suggested that the FEFs may have a previously unknown role in the perception of left-right rotated shapes. A study on feature and spatial priming indicated that these two phenomena have distinct causal mechanisms. The left FEFs appear to access a spatial memory signal during the process of saccade programming. When TMS is applied during this period, the spatial priming benefit is abolished. Altogether, this thesis presents evidence that visuospatial and oculomotor functions can be dissociated in the human FEFs. The data on timing and the effects of learning correspond well with results reported in monkeys. The priming experiment offers the first evidence that the left FEFs are crucial for spatial priming, while the learning study suggests the novel hypothesis that the FEFs are crucial for left-right rotated shape perception.
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Wilman, Henry R. "Computational studies of protein helix kinks." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:21225f0e-efed-49c6-af27-5d3fe78fa731.
Full textAbstract:
Kinks are functionally important structural features found in the alpha-helices of many proteins, particularly membrane proteins. Structurally, they are points at which a helix abruptly changes direction. Previous kink definition and identification methods often disagree with one another. Here I describe three novel methods to characterise kinks, which improve on existing approaches. First, Kink Finder, a computational method that consistently locates kinks and estimates the error in the kink angle. Second the B statistic, a statistically robust method for identifying kinks. Third, Alpha Helices Assessed by Humans, a crowdsourcing approach that provided a gold-standard data set on which to train and compare existing kink identification methods. In this thesis, I show that kinks are a feature of long -helices in both soluble and membrane proteins, rather than just transmembrane -helices. Characteristics of kinks in the two types of proteins are similar, with Proline being the dominant feature in both types of protein. In soluble proteins, kinked helices also have a clear structural preference in that they typically point into the solvent. I also explored the conservation of kinks in homologous proteins. I found examples of conserved and non-conserved kinks in both the helix pairs and the helix families. Helix pairs with non-conserved kinks generally have less similar sequences than helix pairs with conserved kinks. I identified helix families that show highly conserved kinks, and families that contain non-conserved kinks, suggesting that some kinks may be flexible points in protein structures.
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Silva, Josà JÃnior Alves da. "Microscopia de forÃa elÃtrica em amostra de Ãxido de grafeno." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11333.
Full textAbstract:
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoAs estruturas a base de carbono tem um papel de grande importÃncia nos campos da ciÃncia e da tecnologia. Isso graÃas à versatilidade do elemento carbono, pilar da quÃmica orgÃnica, que consegue formar uma diversidade de estruturas (cerca de 10 milhÃes de compostos), alÃm de ser um constituinte bÃsico de toda forma de vida conhecida. Dependendo das condiÃÃes de formaÃÃo, este fenomenal elemento, pode se apresentar em diversas formas alotrÃpicas: desde um material extremamente frÃgil, como o grafite, atà materiais incrivelmente resistentes como o diamante, nanotubos de carbono e o grafeno. Esses materiais grafÃticos tÃm sido extensivamente estudados, apresentando propriedades Ãnicas e grande potencial em aplicaÃÃes tecnolÃgicas. Dentre eles, o grafeno ocupa, atualmente, a posiÃÃo de maior destaque por possuir propriedades mecÃnicas e eletrÃnicas diferenciadas. O Ãxido de grafeno à uma classe de estruturas grafÃticas constituÃda basicamente de uma camada de grafeno decorada com grupos epÃxido e hidroxila na superfÃcie e grupos carboxÃlicos e carbonila nas bordas. A sua estequiometria depende fortemente do mÃtodo de obtenÃÃo. Esse material, alÃm de ser uma das principais rotas para a obtenÃÃo em larga escala do grafeno, tambÃm apresenta diversas propriedades interessantes, que possibilitam, por exemplo, aplicaÃÃes biolÃgicas, uma vez que seus grupos funcionais o tornam bastante reativo alÃm de ser facilmente dispersado em Ãgua. Muitas questÃes relacionadas ao Ãxido de grafeno ainda nÃo estÃo bem esclarecidas, como sua prÃpria estrutura, processo de formaÃÃo e mecanismos de interaÃÃo. Nesse sentido, foi utilizada, como principal ferramenta, a microscopia de forÃa elÃtrica (EFM) para estudar propriedades eletrostÃticas de uma amostra de Ãxido de grafeno obtida utilizando-se um mÃtodo de Hummer modificado. Por meio de um modelo simplificado, foi possÃvel desenvolver um mÃtodo para anÃlise das mediÃÃes de EFM e assim determinar a presenÃa e o sinal da carga lÃquida da amostra. AlÃm de ser possÃvel esclarecer a origem do fenÃmeno de borda observado nos experimentos de EFM.
Carbon-based structures have played a major role in scientific and technological fields. This is due to the versatility of the element carbon, the pillar of organic chemistry, which can form a variety of structures (about 10 million compounds), besides being a basic constituent of all known life forms. Depending on the conditions, this phenomenal element can occur in several allotropic forms: from an extremely brittle material, such as graphite, so incredibly resistant materials such as diamond, carbon nanotubes and graphene. These graphitic materials have been studied extensively, and present unique properties and great potential for technological applications. Among these materials, graphene currently occupies the most prominent position by having special electronic and mechanical properties. The graphene oxide is a class of graphitic structure consisting essentially of a graphene layer decorated with epoxide and hydroxyl groups on the surface and carboxyl and carbonyl groups on the edges. Its stoichiometry depends strongly on the method of production. In addition the graphene oxide is one of the main routes for obtaining large-scale graphene also it has several interesting properties, which allow, for example, biological applications, since their functional groups make it very reactive, besides being easily dispersed in water. Many issues related to graphene oxide are yet unclear, as also its structure, training procedure and mechanisms of interaction. Thus, the electric force microscopy (EFM) was used as the main tool to study electrostatic properties of a graphene oxide sample obtained by a modified Hummer method. By means of a simplified model, it was possible to develop a method for the analysis of the EFM measurements and so determine the presence and the sign of the net charge of the sample. Furthermore it is possible to clarify the origin of the edge phenomenon observed in EFM experiments.
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Calavalle, Francesco. "Caratterizzazione microscopica di un transistor organico a effetto di campo." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7812/.
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Negli ultimi anni uno dei settori di ricerca più interessanti in ambito tecnologico è sicuramente quello dell'elettronica organica. Lo sviluppo è spinto dai vantaggi che portano i dispositivi basati su materiali organici: bassi costi di produzione, facilità di fabbricazione su grandi aree e flessibilità.
In questa tesi andiamo ad esaminare un transistor organico a effetto di campo (OFET) dal punto di vista macroscopico e microscopico, cercando di mettere in relazione le sue caratteristiche morfologiche ed elettriche.
Il dispositivo sottoposto ai test è un OFET realizzato con TIPS-pentacene come semiconduttore. Dai risultati ottenuti si evince che le prestazioni elettriche del transistor sono fortemente legate alla microstruttura assunta dal materiale organico durante la deposizione.
I primi due capitoli illustrano i principi di funzionamento degli OFET e la tecnica SPM (scanning probe microscopy) utilizzata per l'indagine microscopica. Il terzo e quarto capitolo descrivono rispettivamente gli apparati sperimentali e i risultati ottenuti dall'indagine su due aree diverse del dispositivo.
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Xu, JiaPeng. "A Novel Nanoparticle Manipulation Method Using Atomic Force Microscope." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243987021.
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Högvall, Filip. "Simulating changes in Swedish wood supply from increased forest certification : An area-based matrix model approach using National Forest Inventory data and EFDM software." Thesis, Umeå universitet, Nationalekonomi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-159311.
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The first law regarding the protection of Swedish forests was implemented in 1903 and the scope has only ever increased since then. By the 1990s a new method of forest protection was founded in the form of FSC and later also PEFC certification programs. These provide a market-based approach to forest protection by through the use of price premiums incentivize forest owners to participate in voluntary forest conservation. 63% of Swedish productive forests was certified in 2017 and this number has potential to increase which can have significant implications for future forest supply. In this study I use an area-based matrix model on NFI data within the EFDM software to simulate forest supply in the next 100 years in two management scenarios: Current practices and if all forest is managed according to the FSC and PEFC standard. The timber stock is simulated to grow faster when all forest is certified and reach a stable level that is 101 mill. m3sk greater than if forests are managed as today. Harvests are simulated to grow in a similar way but remain lower when all forests are certified than if managed according to current practices. The difference does however decrease slightly as the simulation progresses. The levels of harvest are simulated at substantially lower levels in both scenarios than actual levels due to insufficient information on management in NFI data, indicating a necessity for external information to compliment the NFI.
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Mottaghizadeh, Alireza. "Non-conventional insulators : metal-insulator transition and topological protection." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066652/document.
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Ce manuscrit présente une étude expérimentale de phase isolante non-conventionnelle, l'isolant d'Anderson, induit par le désordre, l'isolant de Mott, induit par les interactions de Coulomb, et les isolants topologiques.Dans une première partie du manuscrit, je décrirais le développement d'une méthode pour étudier la réponse de charge de nanoparticules par Microscopie à Force Electrostatique (EFM). Cette méthode a été appliquée à des nanoparticules de magnétite (Fe3O4), un matériau qui présente une transition métal-isolant, i.e. la transition de Verwey, lors de son refroidissement en dessous d'une température TV~120 K.Dans une seconde partie, ce manuscrit présente une étude détaillée de l'évolution de la densité d'états au travers de la transition métal-isolant entre un isolant de type Anderson-Mott et une phase métallique dans le matériau SrTiO3, et ceci, en fonction de la concentration de dopants, les lacunes d'oxygènes. Nous avons trouvé que dans un dispositif memoresistif de type Au-SrTiO3-Au, la concentration de dopants pouvait être ajustée par migration des lacunes d'oxygènes à l'aide d'un champ. Dans cette jonction tunnel, l'évolution de la densités d'états au travers de la transition métal-isolant peut être étudiée de façon continue. Finalement, dans une troisième partie, le manuscrit présente le développement d'une méthode pour la microfabrication d'anneaux de Aharonov-Bohm avec l'isolant topologique, Bi2Se3, déposée par épitaxie à jet moléculaire. Des résultats préliminaires sur les propriétés de transport quantique de ces dispositifs seront présentésThis manuscript presents an experimental study of unconventional insulating phases, which are the Anderson insulator, induced by disorder, the Mott insulator, induced by Coulomb interactions, and topological insulators.In a first part of the manuscript, I will describe the development of a method to study the charge response of nanoparticles through Electrostatic Force Microscopy (EFM). This method has been applied to magnetite Fe3O4 nanoparticles, a material that presents a metal-insulator transition, i.e. the Verwey transition, upon cooling the system below a temperature Tv=120K. In a second part, this manuscript presents a detailed study of the evolution of the Density Of States (DOS) across the metal-insulator transition between an Anderson-Mott insulator and a metallic phase in the material SrTiO3 and this, as function of dopant concentration, i.e. oxygen vacancies. We found that in this memristive type device Au-SrTiO3-Au, the dopant concentration could be fine-tuned through electric-field migration of oxygen vacancies. In this tunnel junction device, the evolution of the DOS can be followed continuously across the metal-insulator transition. Finally, in a third part, the manuscript presents the development of a method for the microfabrication of Aharonov-Bohm rings with the topological insulator material, Bi2Se3, grown by molecular beam epitaxy. Preliminary results on the quantum transport properties of these devices will be presented
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Correia, Daniel Santos de Quadros. "Análise modal de bombas de cavidades progressivas." Escola Politécnica /Instituto de Matemática, 2017. http://repositorio.ufba.br/ri/handle/ri/22926.
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O objetivo deste trabalho é desenvolver e aplicar uma metodologia para a realização da análise modal experimental em um conjunto de bombeio por cavidades progressivas (BCP), em condições de instalação similares às de poços reais. A técnica utilizada neste trabalho, conhecida como Enhanced Frequency Domain Decomposition (EFDD), é capaz de estimar os parâmetros modais com boa acurácia, mesmo na presença de ruído. Ela pode estimar as frequências naturais e formas modais através da decomposição em valores singulares (SVD - Singular value decomposition) da matriz densidade espectral de potência (PSD - Power spectral density) da resposta do sistema a uma excitação de entrada. A taxa de amortecimento pode ser obtida através do cálculo do decremento logarítmico nas funções de autocorrelação. A primeira etapa do estudo consiste no desenvolvimento de algoritmos para a implementação de alguns métodos de análise modal experimental comuns na literatura. Foram implementados os métodos do Peak picking (PP), do Frequency Domain Decomposition (FDD), EFDD e do Least Square Complex Exponential (LSCE). É utilizado um sinal sintético de parâmetros conhecidos para comparar os resultados obtidos entre tais técnicas. Além disso, este sinal teve alguns parâmetros alterados, a exemplo da razão sinal-ruído, e o comportamento da estimação com estas técnicas foi avaliado. Na etapa seguinte, são analisadas estruturas relacionadas ao conjunto BCP, como a coluna de revestimento, onde o conjunto será instalado, além de um dos seus principais subsistemas, o conjunto rotor-estator. Por fim, é realizada a análise modal experimental do conjunto BCP, no interior do poço de testes, em condições de instalação similares àquelas encontradas em um poço real.
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Wang, Debin. "Thermochemical nanolithography fabrication and atomic force microscopy characterization of functional nanostructures." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34776.
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This thesis presents the development of a novel atomic force microscope (AFM) based nanofabrication technique termed as thermochemical nanolithography (TCNL). TCNL uses a resistively heated AFM cantilever to thermally activate chemical reactions on a surface with nanometer resolution. This technique can be used for fabrication of functional nanostructures that are appealing for various applications in nanofluidics, nanoelectronics, nanophotonics, and biosensing devices.
This thesis research is focused on three main objectives. The first objective is to study the fundamentals of TCNL writing aspects. We have conducted a systematic study of the heat transfer mechanism using finite element analysis modeling, Raman spectroscopy, and local glass transition measurement. In addition, based on thermal kinetics analysis, we have identified several key factors to achieve high resolution fabrication of nanostructures during the TCNL writing process.
The second objective is to demonstrate the use of TCNL on a variety of systems and thermochemical reactions. We show that TCNL can be employed to (1) modify the wettability of a polymer surface at the nanoscale, (2) fabricate nanoscale templates on polymer films for assembling nano-objects, such as proteins and DNA, (3) fabricate conjugated polymer semiconducting nanowires, and (4) reduce graphene oxide with nanometer resolution.
The last objective is to characterize the TCNL nanostructures using AFM based methods, such as friction force microscopy, phase imaging, electric force microscopy, and conductive AFM. We show that they are useful for in situ characterization of nanostructures, which is particularly challenging for conventional macroscopic analytical tools, such as Raman spectroscopy, IR spectroscopy, and fluorescence microscopy.
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Bartolucci, Alberto. "Morphological characterization of ZnS thin films for photovoltaic applications." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10540/.
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Le celle solari a film sottile sono tra le alternative più promettenti nel campo fotovoltaico. La ricerca di materiali non tossici ed economici per la passivazione delle superfici è di fondamentale importanza. Il presente è uno studio sulla morfologia di film sottili di ZnS. I campioni analizzati sono stati cresciuti tramite DC sputtering a diversa potenza (range 50-150W) per studiare le connessioni tra condizioni di deposizione e proprietà strutturali. Lo studio è stato condotto mediante acquisizione di mappe AFM. E' stata effettuata un'analisi dei buchi (dips) in funzione della potenza di sputtering, per individuare il campione con la minore densità di dips in vista di applicazioni in celle solari a film sottile. I parametri strutturali, quali la rugosità superficiale e la lunghezza di correlazione laterale sono stati determinati con un'analisi statistica delle immagini. La densità e dimensione media dei grani sono state ricavate da una segmentazione delle immagini. Le analisi sono state svolte su due campioni di ZnO per fini comparativi. Tramite EFM sono state ottenute mappe di potenziale di contatto. Tramite KPFM si è valutata la differenza di potenziale tra ZnS e un layer di Al depositato sulla superficie. La sheet resistance è stata misurata con metodo a quattro punte. Dai risultati la potenza di sputtering influenza la struttura superficiale, ma in maniera non lineare. E' stato individuato il campione con la minore rugosità e densità di dips alla potenza di 75 W. Si è concluso che potenze troppo grandi o piccole in fase di deposizione promuovono il fenomeno di clustering dei grani e di aumentano la rugosità e densità di dips. E' emersa una corrispondenza diretta tra morfologia e potenziale di contatto alla superficie. La differenza di potenziale tra Al e ZnS è risultata inferiore al valore noto, ciò può essere dovuto a stati superficiali indotti da ossidi. Il campione risulta totalmente isolante.
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Lanzoni, Evandro Martin. "Electric force microscopy techniques on GaAs mesoscopic structures." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/154116.
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As técnicas de microscopia de sonda Kelvin (KPFM) e de microscopia de força eletrostática (EFM) são amplamente utilizadas para analisar a distribuição do potencial de superfície, porém com pouca aplicação em nanoestruturas semicondutoras auto-organizadas embutidas em um substrato. Neste trabalho, investigamos diretamente o acúmulo de carga dentro de estruturas mesoscópicas de GaAs (MGS) [1]. As estruturas são fabricadas através do crescimento sobreposto de um modelo de nano orifícios usando epitaxia de feixe molecular. Para tal, uma combinação de desoxidação assistida por Ga e ataque químico por gotículas localizadas foram utilizadas para criar orifícios iniciais com uma profundidade de ca. 10 a 15nm, que são posteriormente cobertos com 15nm de barreira AlxGax-1As e GaAs com 1nm, 2nm, 5nm, 10nm de espessura. Microscopia de força atômica e microscopia eletrônica de transmissão mostraram que a forma do orifício é preservada durante o crescimento de AlGaAs. Em seguida, esses orifícios são preenchidos com GaAs formando uma estrutura alongada sobre o buraco [1]. Investigamos o potencial de superfície local e a distribuição das cargas nestas estruturas com a técnica KPFM de passagem única. Portanto, uma voltagem AC de 5 V é aplicada a uma ponta metalizada e varremos a amostra no modo de contato intermitente. Observamos uma clara diferença de potencial na região central da estrutura, onde esperamos o furo preenchido. Então, um estudo sistemático com a técnica de KPFM mostrou a influência no acúmulo de carga quando a espessura de GaAs é alterada, bem como, quando modificamos a concentração de Al na barreira de AlGaAs. O cálculo simulando um poço de potencial com barreiras semi-finitas e finitas mostrou que não ocorre acúmulo de carga quando a espessura do GaAs é menor que 1,5 nm, corroborando com nossos resultados. Simulações do diagrama de banda e da densidade de elétron da estrutura permitem atribuir o acumulo de carga observado, aos diferentes níveis de energia da estrutura mesoscópica de GaAs em comparação com as camadas de GaAs circundantes.
Kelvin probe force microscopy and electric force microscopy techniques are widely used to analyze the distribution of the surface potential with little application to self-assembled semiconductor nanostructures embedded into a substrate. In this work, we directly investigate the charge accumulation inside mesoscopic GaAs structures [1]. The structures are fabricated by overgrowth of a nanohole template using molecular beam epitaxy. Therefore, a combination of Ga assisted deoxidation and local droplet etching is used to create initial holes with a depth of ca. 10 to 15nm, which are covered subsequently with 15nm of AlxGax-1As barrier and GaAs caps with 1nm, 2nm, 5nm, 10nm thicknesses. Atomic force microscopy and transmission electron microscopy results showed that the hole shape is preserved during the AlGaAs overgrowth. Then filled with GaAs forming an elongated mount over the hole [1]. We investigate the local potential and the charge distribution in these structures with a single pass Kelvin probe force microscopy technique. Therefore, an AC voltage of 5 V is applied to a metalized tip and scanned in tapping mode over the sample. We observed a clear potential difference in Kelvin probe force microscopy measurements in the middle of the structure, where we expect a filled hole. We systematically study by Kelvin probe force microscopy the influence on the charge accumulation when the GaAs thickness is changed, as well as the Al concentration in the AlGaAs barrier. Calculation of the particle in the box for semi-finite and finite barriers were done and show that no charge accumulation is observed for GaAs thickness lower than 1.5nm in the semi-finite barrier, corroborating with our results. Simulations of band gap and electron wavefunction of the structure allow us to ascribe the charge accumulation observed, to the different confinement of carriers inside of the unstrained mesoscopic GaAs structure compared to the surrounding GaAs layers.
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Li, Xiaxi. "In situ characterization of electrochemical processes of solid oxide fuel cells." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54256.
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Solid oxide fuel cells (SOFCs) represent a next generation energy source with high energy conversion efficiency, low pollutant emission, good flexibility with a wide variety of fuels, and excellent modularity suitable for distributed power generation. As an electrochemical energy conversion device, SOFC’s performance and reliability depend sensitively on the catalytic activity and stability of the electrode materials. To date, however, the development of electrode materials and microstructures is still based largely on trial-and-error methods because of inadequate understanding of the mechanisms of the electrode processes. Identifying key descriptors/properties of electrode materials or functional heterogeneous interfaces, especially under in situ conditions, may provide guidance to the design of electrode materials and microstructures. This thesis aims to gain insight into the electrochemical and catalytic processes occurring on the electrode surfaces using unique characterization tools with superior sensitivity, high spatial resolution, and excellent surface specificity applicable under in situ/operando conditions.
Carbon deposition on nickel-based anodes is investigated with in situ Raman spectroscopy and SERS. Analysis shows a rapid nucleation of carbon deposition upon exposure to small amount of propane. Such nucleation process is sensitive to the presence of surface coating (e.g., GDC) and the concentration of steam. In particular, operando analysis of the Ni-YSZ boundary indicates special function of the interface for coking initiation and reformation.
The coking-resistant catalysts (BaO, BZY, and BZCYYb) are systematically studied using in situ Raman spectroscopy, SERS, and EFM. In particular, time-resolved Raman analysis of the surface functional groups (-OH, -CO3, and adsorbed carbon) upon exposure to different gas atmospheres provides insight into the mechanisms related to carbon removal. The morphology and distribution of early stage carbon deposition are investigated with EFM, and the impact of BaO surface modification is evaluated.
The surface species formed as a result of sulfur poisoning on nickel-based anode are examined with SERS. To identify the key factors responsible for sulfur tolerance, model cells with welldefined electrode-electrolyte interfaces are systematically studied. The Ni-BZCYYb interface exhibits superior sulfur tolerance.
The oxygen reduction kinetics on LSCF, a typical cathode material of SOFC, is studied using model cells with patterned electrodes. The polarization behaviors of these micro- electrodes, as probed using a micro-probe impedance spectroscopy system, were correlated with the systematically varied geometries of the electrodes to identify the dominant paths for oxygen reduction under different electrode configurations. Effects of different catalyst modifications are also evaluated to gain insight into the mechanisms that enhance oxygen reduction activity.
The causes of performance degradation of LSCF cathodes over long term operation are investigated using SERS. Spectral features are correlated with the formation of surface contamination upon the exposure to air containing Cr vapor, H2O, and CO2. Degradation in cathode performance occurs under normal operating conditions due to the poisoning effect of Cr from the interconnect between cells and the high operating temperature. The surface-modified LSCF cathode resists surface reactions with Cr vapor that impairs electrode performance, suggesting promising ways to mitigate performance degradation.
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Riedel, Clément. "Propriétés diélectrique et mécanique des polymères aux échelles macro et nanoscopiques." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2010. http://tel.archives-ouvertes.fr/tel-00582827.
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Le but de cette thèse était tout d'abord d'étudier les théories physiques qui décrivent la dynamique des polymères à l'échelle macroscopique. Le modèle de Rouse et la théorie d'enchevêtrement de P-G. de Gennes décrivent la dynamique des polymères non enchevêtrés et enchevêtrés, respectivement. Nous avons étudié les différentes transitions entre ces deux régimes en utilisant deux techniques expérimentales : Spéctroscopie dielectrique large bande et rhéologie. Un test complet du modèle de Rouse à été effectué en comparant les prédictions de ce modèle pour la dépendance en fréquence de la permittivité diélectrique et du module de cisaillement aux données expérimentales. Les effets d'enchevêtrement sur les spectres diélectriques ont été discutés. Nous avons ensuite développé des méthodes basées sur la microscopie à force électrostatique afin d'étudier les propriétés diélectriques locales. En utilisant une simulation numérique basée sur la Méthode des Charges Equivalentes, nous avons quantifié la constante diélectrique à partir de la mesure du gradient de force crée par un potentiel statique entre une pointe et un diélectrique. Cette méthode permet d'imager la constante diélectrique avec une résolution spatial de 40 nm. Le retard de phase de la composante en 2 omega de la force ou du gradient de force crée par un voltage alternatif est relié aux pertes diélectriques. Nous avons développé un mode d'imagerie des pertes diélectriques. Cette méthode simple pourrait être appliqué en biologie ou matière molle en générale afin d'étudier des variations locales de constantes dielectriques.
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Habrard, Florian. "Élaboration de dispositifs et matériaux mixtes à base de polymères conjugués électroluminescents." Phd thesis, Université Joseph Fourier (Grenoble), 2006. http://tel.archives-ouvertes.fr/tel-00130247.
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Le sujet de cette thèse se situe dans le contexte de l'électronique organique à base de polymères conjugués. Nous avons choisi la famille des polyfluorènes principalement en raison de leur émission dans le bleu, leur bon rendement quantique ainsi que pour la facilité avec laquelle on peut modifier leurs propriétés en greffant différents groupements fonctionnels sur la structure de base du fluorène. L'originalité des recherches effectuées au laboratoire concerne la structure des dispositifs électroluminescents (cellules électrochimiques électroluminescentes ou OLEC) que nous réalisons. Leur principe de fonctionnement repose sur l'utilisation de liquides ioniques ajoutés directement au polymère conjugué sans l'intervention d'un polymère conducteur ionique. Le travail réalisé au cours de cette thèse a principalement consisté à tenter d'améliorer les performances du polyfluorène par l'utilisation de groupements fonctionnels permettant d'augmenter la compatibilité polymère / liquide ionique. Dans cette optique, nous avons mis en œuvre l'utilisation d'un outil de caractérisation particulièrement adapté à nos échantillons : la microscopie à force atomique en mode EFM ou KFM. Cela nous a permis de visualiser précisément la séparation de phase entre le polymère et le liquide ionique. Nous avons ainsi pu montrer que le courant dans un dispositif était grossièrement proportionnel à l'interface polymère / liquide ionique. Nous avons alors proposé une hypothèse expliquant le mode de vieillissement des OLEC. L'amélioration du mélange, c'est-à-dire la maximisation de l'interface polymère / liquide ionique devrait ainsi permettre d'améliorer la durée de vie des dispositifs. L'utilisation de groupements PEO et cyano greffés sur le polyfluorène semble une voie à explorer. Enfin, nous avons décrit le comportement particulier du mélange polyfluorène cyano – THA-TFSI dont la morphologie évolue suivant les conditions de température et de pression.
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Notari, Airton Carlos. "Estudo de incorporações de impurezas doadoras em estruturas semicondutoras III-V crescidas por epitaxia por feixes moleculares." Universidade de São Paulo, 1993. http://www.teses.usp.br/teses/disponiveis/54/54132/tde-09032009-150110/.
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Amostras de Semicondutores III-V foram crescidas usando a técnica de Epitaxia por feixes Moleculares. As propriedades elétricas das estruturas de GaAs com dopagem planar com Silício foram investigadas, e também a saturação e a difusão do Silício nestas amostras. As propriedades ópticas e elétricas das estruturas dopadas planarmente com Selênio foram analisadas, usando as técnicas de Capacitância-voltagem e a de Tunelamento resonante. As propriedades elétricas dos poços quânticos a base de InGaAs/GaAs foram investigadas, em função da posição da impureza planarmente dopada com Silício.III-V semiconductor samples were grown using the Molecular beam epitaxy technique, the electrical properties of the GaAs structures planar doped with silicon were investigated as well as the Silicon saturation and diffusion in these samles. The optcal and electrical properties of structures planar doped with Selenium were analyzed using the Capacitance Voltage and resonant Tunneling techniques. The electrical properties of InGaAs/ GaAs based quantum wells were investigated as a function of the planar doped with Silicon impurity position.
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Li, Wei. "Investigation of Pseudo-Passive Layer Formation in CO2 Corrosion." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1307119897.
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Chevtchenko, Serguei Aleksandrovich. "DEFECTS IN GaN: AN EXPERIMENTAL STUDY." VCU Scholars Compass, 2007. http://scholarscompass.vcu.edu/etd_retro/72.
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This work examines extended, point, and surface defects in GaN by means of electric force microscopy, photoluminescence and deep-level transient spectroscopy. Modeling of the surface band bending, its origin, and the effects of fabrication processing steps are discussed in the first part of the dissertation. Experimental results indicate that spontaneous polarization does not play a predominant role in GaN band bending. An increase of surface band bending due to annealing and etching was observed, while passivation did not produce changes. However, passivation did reduce reverse-bias leakage current by one to two orders of magnitude in GaN Schottky diodes. The optical properties of GaN were found to be sensitive to fabrication processing steps, most likely due to changes in the total density of surface states.The second part of this dissertation concerns the reduction of extended defects and associated deep levels in layers of GaN grown on different templates. Templates employing a low temperature GaN nucleation layer, epitaxial lateral overgrowth, and SiNx nanonetwork are compared in terms of deep level concentrations in the resulting GaN films. The concentrations of two types of traps, A (Ec-ET ~ 0.54-0.58 eV) and B (Ec-ET ~ 0.20-0.24 eV), were the highest for the sample with a low temperature nucleation layer and lowest for a sample with a 6 min SiNx deposition time. We surmise that the defects responsible for the dominant trap A are located along dislocation lines and form clusters.In the last part we investigate the piezoelectric and ferroelectric properties of PZT in Pb(Zr, Ti)O3(PZT)/GaN structures, and the effects of interface states. Sol-gel derived thin PZT films on GaN and Pt/Ti/SiO2/Si surfaces were studied by piezoresponse force microscopy (PFM), where quantitative characterization of piezoelectric properties of PZT films was performed. Superior piezoelectric properties of PZT/GaN/sapphire structures as compared to PZT/ Pt/Ti/SiO2/Si structures were observed and explained by a different preferred orientation of PZT. Despite the possible existence of a strong depolarization field at the PZT/GaN interface, we confirm with PFM the presence of a remanent polarization in PZT/GaN/sapphire structures.
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Vernié, Tatiana. "Analyse fonctionnelle d'EFD, un régulateur transcriptionnel de la nodulation au cours de l'interaction symbiotique entre Medicago truncatula et Sinorhizobium meliloti." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/222/.
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Les Légumineuses sont capables d'établir une interaction symbiotique avec des bactéries de la rhizosphère, appelées Rhizobia. Cette interaction implique deux processus strictement contrôlés par la plante : une infection bactérienne et la formation d'un nouvel organe : le nodule, dans lequel l'azote atmosphérique est réduit. Les mécanismes de ces contrôles restent peu connus. A partir d'études transcriptomiques, nous avons sélectionné un régulateur potentiel, EFD (Ethylene response Factor required for nodule Differentiation), codant pour un facteur de transcription de type ERF. Le profil d'expression d'EFD a été caractérisé par des analyses de RT-PCR quantitatives, d'hybridation in situ et de fusions promoteur:GUS. Ces études ont révélé une expression spécifique d'EFD dans les primordia nodulaires et racinaires, ainsi que dans la zone d'infection des nodules, où les bactéries et tissus végétaux se différencient. Puis, grâce à des approches de surexpression et de RNAi sur des racines transformées, et à l'analyse d'un mutant de délétion, un rôle d'EFD lors de l'initiation et de la différenciation des nodules a été mis en évidence. Enfin, une cible principale, Mt RR4, a été identifiée par une approche transcriptomique. RR4 code pour un régulateur de la réponse aux cytokinines, dont le rôle lors de l'initiation des nodules a récemment été démontré. Nous proposons donc qu'en régulant l'expression de RR4, EFD modulerait la voie de réponse des cytokinines lors de la nodulation et coordonnerait ainsi l'initiation et le développement des nodules. .Leguminous plants can establish symbiotic interaction with bacteria from the rhizosphere, called Rhizobia. During this interaction, plants control tightly two mechanisms: bacterial infection and formation of a new organ, the nodule in which nitrogen is fixed. But how plants control these mechanisms is still largely unknown. Starting from transcriptomic studies, we selected a potential regulator, EFD (Ethylene response Factor required for nodule Differentiation), coding for a transcription factor belonging to the ERF family. The expression profile of EFD has been characterized by quantitative RT-PCR, in situ hybridization and promoter:GUS fusion. These studies revealed a specific expression of EFD in nodule and root primordia, and in the infection zone of mature nodules, where bacteria and plant tissues differentiate. Using overexpression and RNAi approaches on transformed roots, and study of a deletion mutant, we then showed that EFD plays a role to control the number of nodules and their differentiation. Finally, we identified a major target of EFD by a transcriptomic approach. This target, Mt RR4, encodes a cytokinin response regulator. Cytokinins have recently been shown to be positive regulators of nodule initiation. Consequently, we propose that by regulating RR4 expression, EFD modulates the cytokinin pathway during nodulation to coordinate nodule initiation and development. .
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Imran, Saeed Sohail. "Investigation of Mechanisms for Spur Generation in Fractional-N Frequency Synthesizers." Thesis, Linköpings universitet, Elektroniksystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-80886.
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With the advances in wireless communication technology over last two decades, the use of fractional-N frequency synthesizers has increased widely in modern wireless communication applications due to their high frequency resolution and fast settling time. The performance of a fractional-N frequency synthesizer is degraded due to the presence of unwanted spurious tones (spurs) in the output spectrum. The Digital Delta-Sigma Modulator can be directly responsible for the generation of spur because of its inherent nonlinearity and periodicity. Many deterministic and stochastic techniques associated with the architecture of the DDSM have been developed to remove the principal causes responsible for production of spurs. The nonlinearities in a frequency synthesizer are another source for the generation of spurs. In this thesis we have predicted that specific nonlinearities in a fractional-N frequency synthesizer produce spurs at well-defined frequencies even if the output of the DDSM is spur-free. Different spur free DDSM architectures have been investigated for the analysis of spurious tones in the output spectrum of fractional-N frequencysynthesizers. The thesis presents simulation and experimental investigation of mechanisms for spur generation in a fractional-N frequency synthesizer. Simulations are carried out using the CppSim system simulator, MATLAB and Simulink while the experiments are performed on an Analog Devices ADF7021, a high performance narrow-band transceiver IC.
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Sundström, Ulla. "Mässhaken i förändring." Thesis, University of Gävle, Department of Humanities and Social Sciences, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-488.
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Mitt syfte är att ta reda på om mässhaken har ändrat sitt utseende på något vis. Jag har försökt följa mässhakens utveckling från den allra tidigaste kristendomen till i dag. Vilken form av förändring har skett hos mässhaken? Har reformationen påverkat mässhaken på ett eller annat sätt? Finns det någon politisk eller social påverkan som kan ses i mässhaken? Har den möjligen påverkats av modet? Varifrån kommer mässhaken och hur har den fått sin nuvarande form?
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Murteira, Martinho José Badagola. "Caracterização da qualidade da água para rega nas captações do sistema Alqueva-Pedrogão." Master's thesis, Universidade de Évora, 2009. http://hdl.handle.net/10174/18527.
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O Empreendimento de Fins Múltiplos de Alqueva (EFMA) é um projecto estruturante centrado na barragem do Alqueva, que pretende garantir o recurso Água na região e com isso viabilizar uma série de infra-estruturas que contribuirão para o desenvolvimento, em termos económicos e sociais, de uma das regiões mais desfavorecidas da Europa. O EFMA é constituído pelo "Reservatório Mãe" e por um conjunto de outras albufeiras de menor dimensão, interligados por uma rede com cerca de dois mil quilómetros de canais e condutas e mais de meia centena de estações de bombagem, contemplando os seguintes usos da água: - Abastecimento público. - Fornecimento de água para o desenvolvimento de actividades agrícolas e agro-industriais; - Produção de energia; Este trabalho tem por objectivo avaliar a adequabilidade da qualidade da água para o uso rega na origem e produzir informação adequada de suporte à decisão. Os resultados obtidos permitem afirmar que de um modo geral a qualidade da água captada no sistema Alqueva- Pedrógão é adequada para o uso rega, apesar de se verificar uma persistente contaminação de coliformes fecais. ABSTRACT; The Multipurpose Alqueva Project (EFMA- Empreendimento de Fins Múltiplos de Alqueva) is a groundwork project centred in Alqueva dam and its reservoir, which intends to guarantee a strategic water reserve in the region, and therefore making possible a series of associated infrastructures, contributing for the potential development of the region, in economic and social terms, in one of the most poorest regions of Europe. The EFMA includes a "Main Reservoir" and set of other dams with lesser dimension, connected by a several canals and pipelines about two thousand kilometers long (including Primary and Secondary Network), and about 50 pumping stations, with the goal of attaining the following main objectives: - Water supply for the development of agricultural and agro-industrial activities; - Production of energy; - Public Water Supply. This study intends to evaluate the suitability of water quality in the origin for irrigation use and to achieve adequate information for support decision. The results have revealed that the quality of water abstracted in the Alqueva - Pedrógão System is suitable for irrigation, although the persistent contamination of fecal coliforms.
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Markwick, Rachel Loretta Lane. "Regulation of DAG lipase activity : implications for 'on-demand' endocannabinoid signalling." Thesis, King's College London (University of London), 2015. http://kclpure.kcl.ac.uk/portal/en/theses/regulation-of-dag-lipase-activity--implications-for-ondemand-endocannabinoid-signalling(8480a494-ef2d-4b4e-9fcc-891b49ecf8d3).html.
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The diacylglycerol lipases (DAGL α and β) are key enzymes in the biosynthesis of 2-AG, the major endocannabinoid (eCB) in the brain. 2-AG acts on CB1 and/or CB2 receptors and DAGL-dependent eCB signalling regulates a large number of responses including axonal growth during development, as well as neurogenesis and retrograde synaptic plasticity in the adult. The enzymes also play a major role in driving pathogenic inflammatory responses via a DAGL/MAGL pathway that generates arachidonic acid as a precursor to prostaglandin synthesis. DAGL antagonists are being developed as novel therapeutics based on their ability to regulate eCB-mediated signalling and/or inflammatory responses, but the mechanisms underlying the regulation of these enzymes is poorly understood. The DAGLs appear to display ‘on-demand’ synthesis, generating increasing amounts of 2-AG in response to cellular messengers. Using a bioinformatics approach, we have postulated that phosphorylation is key mechanism for regulation of DAGL function. We overexpressed each enzyme in U2OS cells that harbour the Tango assay system. We showed the transgenic DAGLs to be expressed at the membrane, and DAGLα to be active using surrogate substrates. We measured an eCB-dependent CB1 response in the Tango assay, with evidence for kinase activation-dependent eCB signalling, but only a portion of this response appeared to be DAGL-dependent. As a result, we are pursuing a genetic strategy to systematically ‘switch off’ endogenous eCB production. We first targeted the DAGLs using the CRISPR/Cas9 system, using both wild-type and nickase Cas9. Our next strategy will be to knockout other eCB-producing enzymes in these cells to tease out which enzymes are resulting in the eCB-CB1 activation in the Tango assay. This will also provide us with a ‘parent’ cell line to support future mutagenesis studies to understand which (if any) phospho-sites are important for DAGL regulation.
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Quinlan, John Mathew. "Investigation of driving mechanisms of combustion instabilities in liquid rocket engines via the dynamic mode decomposition." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54343.
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Combustion instability due to feedback coupling between unsteady heat release and natural acoustic modes can cause catastrophic failure in liquid rocket engines and to predict and prevent these instabilities the mechanisms that drive them must be further elucidated. With this goal in mind, the objective of this thesis was to develop techniques that improve the understanding of the specific underlying physical processes involved in these driving mechanisms. In particular, this work sought to develop a small-scale, optically accessible liquid rocket engine simulator and to apply modern, high-speed diagnostic techniques to characterize the reacting flow and acoustic field within the simulator. Specifically, high-speed (10 kHz), simultaneous data were acquired while the simulator was experiencing a 170 Hz combustion instability using particle image velocimetry, OH planar laser induced fluorescence, CH* chemiluminescence, and dynamic pressure measurements. In addition, this work sought to develop approaches to reduce the large quantities of data acquired, extracting key physical phenomena involved in the driving mechanisms. The initial data reduction approach was chosen based on the fact that the combustion instability problem is often simplified to the point that it can be characterized by an approximately linear constant coefficient system of equations. Consistent with this simplification, the experimental data were analyzed by the dynamic mode decomposition method. The developed approach to apply the dynamic mode decomposition to simultaneously acquired data located a coupled hydrodynamic/combustion/acoustic mode at 1017 Hz. On the other hand, the dynamic mode decomposition's assumed constant operator approach failed to locate any modes of interest near 170 Hz. This led to the development of two new data analysis techniques based on the dynamic mode decomposition and Floquet theory that assume that the experiment is governed by a linear, periodic system of equations. The new periodic-operator data analysis techniques, the Floquet decomposition and the ensemble Floquet decomposition, approximate, from experimental data, the largest moduli Floquet multipliers, which determine the stability of the periodic solution trajectory of the system. The unstable experiment dataset was analyzed with these techniques and the ensemble Floquet decomposition analysis found a large modulus Floquet multiplier and associated mode with a frequency of 169.6 Hz. Furthermore, the approximate Rayleigh criterion indicated that this mode was unstable with respect to combustion instability. Overall, based on the positive finding that the ensemble Floquet decomposition was able to locate an unstable combustion mode at 170 Hz when the operator's time period was set to 1 ms, suggests that the dynamic mode decomposition based 1017 Hz mode parametrically forces the 170 Hz mode, resulting in what could be characterized as a parametric combustion instability.
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Bica, Manuel Francisco Pinela Aires da. "Barragem do Pisão - análise dos aspectos condicionantes na sua construção." Master's thesis, Universidade de Évora, 2010. http://hdl.handle.net/10174/20859.
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O presente trabalho descreve as principais características da barragem do Pisão e aborda as principais alterações efectuadas durante a empreitada de construção. Descreve os materiais utilizados na construção, caracteriza a fundação, bem como, a metodologia adoptada para a realização do aterro experimental da barragem. Simultaneamente procura identificar e caracterizar alguns dos principais problemas que foram detectados na concepção e construção e que, como tal, condicionam a sua execução. Por fim, apresenta-se paralelamente algumas sugestões, que sirvam de orientação para futuros projectos a implementar de idêntica natureza. – ÁBSTRACT: This study aim to describe the most relevant characteristics of Pisão dam at the sarne time it focus upon the main changes undertaken during the construction works. Construction materials description, foundation characterization and work method used during construction of the dam landfill, are presented. Furthermore, the study seeks to identify and characterize the main constraints that have limited the project execution during the dam conception and construction. Finally, some suggestions that may be used as major guidelines in similar projects, are also presented.
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SILVA, JÚNIOR João Ferreira da. "Um Algoritmo para Distribuição Balanceada de Carga Elétrica e Redução de Consumo de Energia em Centros de Dados e Nuvens." Universidade Federal de Pernambuco, 2013. https://repositorio.ufpe.br/handle/123456789/12376.
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Os avanços tecnológicos acontecem por intermédio de pesquisas e estudos, inclusive com a criação de novos paradigmas, tais como a computação em nuvem, comércio eletrônico e redes sociais. Em alguns casos, grandes centros de dados são utilizados para suportar esses paradigmas. Com isso, estes grandes centros de dados tornaram-se elementos críticos no desenvolvimento de tarefas diárias, o que sugere que, a cada dia, utilizamos mais seus recursos, aumentando a demanda e, consequentemente, o consumo elétrico. Hodiernamente, o consumo de energia é uma questão de interesse comum. Pesquisas demonstram que, como consequência da constante evolução e expansão da tecnologia da informação, os centros de dados e as nuvens (cloud computing) são grandes consumidores de energia elétrica. Com esse alto consumo, destacam-se as questões de sustentabilidade e custo. Neste contexto, a presente dissertação propõe um algoritmo de distribuição de carga elétrica (ADCE) para otimizar a distribuição de energia em infraestruturas elétricas de centros de dados e nuvens privadas. O ADCE é suportado pelo ambiente denominado Mercury, que é capaz de realizar uma avaliação integrada das métricas de confiabilidade, custo e sustentabilidade. O ADCE otimiza, mais especificamente, a distribuição da corrente elétrica na modelagem de fluxo de energia (EFM - Energy Flow Model). A modelagem em EFM é responsável por estimar as questões de sustentabilidade e de custo das infraestruturas elétricas de centros de dados e nuvens, respeitando as restrições de capacidade de energia que cada dispositivo é capaz de fornecer (considerando o sistema elétrico) ou extrair (considerando o sistema de refrigeração). Ademais, dois estudos de caso são apresentados, onde são analisadas sete infraestruturas elétricas de um centro de dados e seis de uma nuvem privada. Para os centros de dados foi alcançada uma redução no consumo de energia de até 15,5% e a métrica utilizada para avaliar a redução do impacto ambiental (exergia) foi reduzida em mais da metade de seu valor. No que concerne ao estudo das nuvens privadas a redução do consumo de energia foi de até 9,7% e da exergia de para quase um terço de seu valor inicial. Os resultados obtidos foram significativos, uma vez que as preocupações ambientais ganham destaque com o passar dos anos e os recursos financeiros das empresas são finitos e muito valiosos.
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McNulty, Mel William Edward. "Military intervention in theory and practice : French policy in sub-Saharan Africa since 1960." Thesis, University of Portsmouth, 1999. https://researchportal.port.ac.uk/portal/en/theses/military-intervention-in-theory-and-practice-french-policy-in-subsaharan-africa-since-1960(deb36e31-efed-4e14-b218-17bcefea10eb).html.
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French military intervention in sub-Saharan Africa since 1960 has operated according to a bilateral dynamic independent of - although often influenced by and justified in terms of - global ideological or bloc alignments. It has been characterised by mechanical responses to perceived intervention stimuli. It has frequently disregarded international law and contradicted France's self-image as homeland and promoter of human rights. It reached its nadir as a result of French support for the genocidal regime in Rwanda. Accordingly, this study advances two principal arguments: French military intervention in sub-Saharan Africa has been driven by a unique French or Franco-African dynamic which has operated largely independently of global bloc politics and geostrategy; and the first failure of French intervention - in Rwanda from 1990 up to and including 1994 - marked a watershed in the practice, and the beginning of a military retreat from the continent more forced than voluntary. International Relations intervention theory has typically disregarded the Franco-African interventionary system, although France acts in defence of its allies and interests as Realism tells us it will, in an interventionary sphere of influence comparable to that of the US in Latin America. This study considers France's legitimisation for its interventions through claimed derogations from the non-intervention norm, and identifies France's unique interventionary dynamic which arose from its regular activation of mechanical responses to perceived intervention stimuli. The context for these responses may be found in France's unique role in Africa since decolonisation. Throughout the Cold War, France was given carte blanche by the West to intervene in its exclusive African sphere, often in breach of those states' sovereignty. This derogation from international norms was made possible by the French-controlled creation of the new states to emerge from decolonisation, the sovereignty of which was deliberately circumscribed by military accords so that intervention frequently became an automatic feature of interstate relations along the Franco-African axis. This study's empirical focus - the uniqueness of this axis in the international system - was demonstrated by the continuity of French interventionary behaviour in the early 1990s, with no immediate change correspondent to the global shift in the balance of power and in the use and justification of military intervention. A perceived need to rework the legitimisation of French intervention only came about in 1994, during preparation for Operation Turquoise in Rwanda, following the first failure of intervention (and the collapse of a French-backed army and regime) in France's African sphere. Although the justificatory discourse of French military intervention was changed at this time to embrace a humanitarian agenda under a UN mandate, its practice changed - to a reluctant observance of the nonintervention norm - against France's will, and only as a result of the transformation since 1994 of the political and military environment in central Africa.
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Cooper, Sharon Rose. "δ-Protocadherin Function: From Molecular Adhesion Properties to Brain Circuitry." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492457066344753.
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Aba'a, Ndong Arthur. "Décharges à barrière diélectrique pulsées de volume et de surface appliquées à la précipitation électrostatique et à la régénération de surface." Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2322/document.
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Dans le cadre de cette thèse, des Décharges à Barrières Diélectrique (DBD) pulsées de volume et de surface ont été étudiées expérimentalement, dans le but de les appliquer respectivement à la précipitation électrostatique de particules submicroniques et à la régénération de surface.La caractérisation des DBD pulsées a consisté à effectuer des mesures électriques (courant, énergie) et optiques (imagerie ICCD), afin d'observer l'influence des paramètres électriques et géométriques, ainsi que des matériaux utilisés, sur les propriétés de la décharge. Il en ressort que pour les deux types de DBD (surface et volume), le courant présente deux pics durant les fronts montant et descendant du pulse de tension, et que les deux décharges ont des aspects différents (filamentaire ou diffus).Concernant la précipitation électrostatique, l'efficacité de collecte des électrofiltres a été déterminée par des mesures granulométriques. Les résultats montrent que celle-ci est influencée par les paramètres électriques et géométriques des électrofiltres. Une caractérisation des phénomènes EHD au sein des électrofiltres par métrologie optique (LDV et PIV) a été effectuée afin de comprendre les mécanismes de charge et de dérive des particules.Ensuite, la régénération de surface a été étudiée en analysant les images de la surface polluée, avant et après le traitement. Les résultats révèlent que les performances de la régénération sont influencées par les paramètres électriques, géométriques et les matériaux des réacteurs DBD. Les mécanismes de la régénération ont été analysés en relevant l'évolution de la taille et la concentration des particules générées lors du processus de régénérationAs part of this thesis, volume and surface pulsed Dielectric Barrier Discharges (DBD) were investigated experimentally for applications in the electrostatic precipitation of submicron particles and surface regeneration, respectively. First, the characterization of pulsed DBDs consisted of performing electrical measurements (current, power) and optical measurements (ICCD imaging) in order to observe the influence of electrical and geometrical parameters as well as materials on the properties of the discharge. It is demonstrated that for both types of DBD (surface and volume), the current has two peaks during the rising and falling times of the voltage pulse, corresponding to distinct streamer and glow discharge regimes, respectively.Next, the collection efficiency of electrostatic precipitation (ESP) was determined by granulometric measurements. The results show that the efficiency is influenced by the electrical and geometrical parameters of the precipitator. A characterization of EFD phenomena was performed inside the precipitator by optical metrology (LDV and PIV) to understand the mechanisms of charge and particle drift. Finally, surface regeneration was investigated by analyzing images of the contaminated surface, before and after treatment. The results reveal that the regeneration process is influenced by electrical and geometrical parameters and DBD reactor materials. The mechanisms of regeneration were analyzed in-situ by measuring changes in the size and concentration of the generated particles during the process of regeneration
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Smit, Imogan. "The application of the business judgment rule in fundamental transactions and insolvent trading in South Africa : foreign precedents and local choices." Thesis, University of the Western Cape, 2016. http://hdl.handle.net/11394/5523.
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Vaillancourt, Kyla. "Maternal history of abuse and maternal 'mind-mindedness' in a sample of mothers with severe mental illness treated in a mother-baby inpatient unit." Thesis, King's College London (University of London), 2015. http://kclpure.kcl.ac.uk/portal/en/theses/maternal-history-of-abuse-and-maternal-mindmindedness-in-a-sample-of-mothers-with-severe-mental-illness-treated-in-a-motherbaby-inpatient-unit(62058c25-ef0d-474c-9e94-8b3c5cb1837e).html.
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The objective of this paper is to systematically review the literature that has examined maternal self-reported history of abuse in relation to an observational assessment of infantmother interaction. Electronic databases were searched and studies that met pre-defined criteria were included. A total of 13 studies (representing 12 independent samples) were included and assessed for quality using the EPHPP tool. Nine of the 13 studies (69% of reviewed articles) found a relationship between self-reported abuse and observed caregiving. Due to variation in sample characteristics and measurement the ability to compare studies is limited. Studies identified as having the highest methodological quality were most consistent, reporting an indirect effect of maternal abuse history on caregiving via parenting stress or depressive symptoms. This review would support the notion that self-reported abuse history in the mother is a risk factor for non-optimal caregiving behaviours; however there is a need for greater understanding of what pathways are responsible for this effect. The current review discusses strengths and limitations of the existing literature and offers suggestions for future research.
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Lin, Y. J., and 林揚展. "The weighting function and base functionof EFM." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/17973084109774270426.
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碩士國立中央大學
土木工程研究所
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The weighting function and base function of EFM ABSTRACT Keywords：element free，weighting function，base function，moving least square In this thesis,treatment of the interpolated function including the weighting and base functions in the element free method is studied in detail. The element free method(EFM) is a newly proposed numerical method in applied mechanics. This method is formulated by a technique so called “ moving least square”(MLS) to interpolate the discrete data within the domain to be analysed. Both the weighting and base functions influence the interpolated function which controls the accuracy of solving solid mechanics problems. After introducing many kinds of weighting function,the cantliver beam problems have been solved with EFM in diffrent kind weighting function and different base function. Numerical examples illustrate that some kinds of weighting function will get better solutions than others. After all,the rule of the choice of the weighting function has been presented. Numerical examples illustrate that the 2 order base function will get better solutions than the 1order base function in some problems.
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Kaminski, Tom. "Coupled electrostatic-mechanical analysis of probes used in Dynamic EFM." 2004. http://hdl.handle.net/1993/16309.
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Long, Stephen A. "A COGNITIVE COMPENSATION MECHANSIM FOR DEFORMABLE ANTENNAS." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-521.
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This thesis presents the design, theory, and measurement of a linearly polarized microstrip patch antenna with a novel substrate-integrated mechanism that can compensate the detuning effects from a physical deformation. Specifically, this antenna bends sharply through the center up to 90 (pivoted about the ground plane) and retuning (compensation) occurs by displacing electromagnetically functionalized colloidal dispersions (EFCDs) through a capillary in the substrate (parallel to the radiating edge). The displacement of a high permittivity EFCD by a low permittivity EFCD acts as a net length reduction (shown mathematically using perturbation theory). This mitigates the physical length extension from the deformation and stretching of the conductors. The design can be considered cognitive (conceptually in this thesis) by allowing the deformation and resulting compressive forces in the substrate to actuate displacement.
The antennas to demonstrate this concept have been chosen to operate at 3 GHz and use a Sylgard 184 (a flexible silicone-based elastomer) substrate material with a height of 4 mm. Simulations of an HFSS model demonstrate a stable VSWR 2:1 bandwidth of 141 MHz across the entire range of bending. Currently available fabrication methods and EFCD material systems provide some limitations. Therefore, proof-of-concept is provided using 2 microstrip patch antennas (one flat patch and one patch bent 90) designed using 4 mm thick Rochelle Foam substrates and rigid copper sheets. A flexible patch was fabricated using Sylgard 184 and SEC 1233 (a conductive elastomer) but bending created several tears in the material and delaminating of the flexible conductor. However, the comparison of trends between simulated and measured results show good agreement and are used to validate this compensation mechanism.
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Tasi, Ming-Shiung, and 蔡明雄. "Blind Equalizer and Timing Recovery Circuit Design for 100Mbps Receiver of Mixed Copper/Fiber EFM Systems." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/00082450140751639973.
Full textAbstract:
碩士國立中央大學
電機工程研究所
94
In recent years, all kinds of network application have been develoed, and bandwidth is not satisfied with appetite of consumers. From Modem to present Asymmetric Digital Subscriber Line(ADSL) and Cable Modem, the bottleneck is user’s bandwidth develop(First Mile/Last Mile). The speed is unable to promote, and the price of the ethernet service is a very heavy burden to users. If ethernet connects directly to user, then the ethernet signal will transmit to user. Hence, this will save unnecessary transmit equipment, bandwidth and has at least 10 Mbps data rate. We build EFM receiver simulation platform utilizing Matlab with finite wordlength. This simulation includes blind equalizer, timing recovery loop. In this simulation, equalizer coefficients convergence and does not need any training sequence. This equalizer can operate at least at data rate of 100Mbps with system requirement, where a 9bit ADC is used for sampling the receiver signal. And, we utilize some techniques to reduce the circuit area .The timing recovery loop contains timing extracting circuit, loop filter and NCO. The timing error detects from equalizer output. We utilize PLL and NCO to adjust sampling phase of ADC. The correction range of timing recovery loop is ±200ppm.
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Belz, Michael. "Competitive, Neutral, or Cooperative Outcome Interdependence? - Consequences on the Behavioral and Perceptional Level." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-EF5D-F.
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Schmitt, Vanessa. "Social and Physical Cognition in Old World Monkeys - A Comparative Perspective." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-EF6D-B.
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Schliehe-Diecks, Susanne. "Sex-specific differences in dispersal propensities and their consequences for grey mouse lemurs (Microcebus murinus)." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-EF7D-7.
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Roloff, Stephanie. "Analysis of CRM1- and Nup214- dependent nuclear export of proteins." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-EF8D-3.
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Ostertag, Karoline Dorothea. "Analyse der Rolle des Purin-Rezeptors P2X4 in der Pathophysiologie der Amyotrophen Lateralsklerose durch vergleichende Untersuchung seiner Expression im ALS-Mausmodell und humanen Gewebe." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-EF9D-0.
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Brinkmann, Bastian Gerrit. "UNtersuchung der unterschiedlichen Funktion des Neuregulin-1 im Hinblick auf die Myelinisierung des peripheren und zentralen Nervensystems." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-EFAD-C.
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