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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Non-Contact Lap Splices in Dissimilar Concretes

Grant, James Philip 14 September 2015 (has links)
Non-contact lap splices placed within a single concrete placement are often used and have been studied in previous research projects. However, non-contact lap splices used with each bar in a different concrete placement such that there is a cold joint between the bars, have not been investigated. This situation is found in the repair of adjacent box beam bridges and in the construction of inverted T-beam systems, among others. It is vital to understand whether the same mechanisms are present across a cold joint with two different types of concrete as are present in traditional non-contact lap splices. In this research, eight T-beam specimens with non-contact lap splices were tested. The spacing between the bars, the splice bar blockout length, and presence of transverse bars were varied to study the effectiveness of the splices. The beams were tested in four point bending so that the splice region was under constant moment and the tension forces in the spliced bars were constant. End and midspan deflections were measured along with surface strain measurements at midspan and at the quarter span points, top and bottom. Gap openings were also measured at the ends of the blockouts. The main conclusions found from this research are that beams containing non-contact lap splices were able to develop nominal capacity with the bar spacing less than or equal to 4 in. and the blockout between 17 and 20 in. long. Extending the blockouts and adding transverse bars underneath the splices did not add to the capacity. / Master of Science
172

Vi är med eleverna hemma : En studie av lärares erfarenheter av Flippad undervisning / We are with the Pupils at Home : a Study of Teachers' Experiences of Flipped Teaching

Bäcklund, Johan January 2016 (has links)
Den här studien undersöker lärares erfarenheter av Flippad undervisning (Flipped Classroom). I den här studien har två forskningsfrågor ställts till ämneslärare i grund- och gymnasieskolan: Vad karaktäriserar Flippad undervisning? samt Vad är syftet med Flippad undervisning?. Teoretisk utgångspunkt i studien är ett sociokulturellt perspektiv. Empirin har samlats in genom kvalitativa intervjuer, analyserade enligt den kvalitativa innehållsanalysen som metodansats. Nio lärare, baserade på ett kriterieurval, från olika kommuner i den södra delen av Sverige har utgjort empirin i studien. Samtliga lärare har intervjuats vid sina respektive arbetsplatser. Fem teman har utkristalliserat sig i resultatet med utgångspunkt i den första forskningsfrågan: Förändrad yrkesroll, Tiden, Att motivera eleverna och ha en kontinuitet, Tekniken samt Kommunikationen med eleverna. Den andra forskningsfrågan genererade tre teman i resultatdelen: Förståelseförberedande, Elevers lärande synliggörs och Tillgänglighet. Resultatet belyser att läraren blir mer av en handledare i klassrummet, tid frigörs under lektionen som medger en förändrad, och ökad kommunikation. Resultatet visar också att det är viktigt att göra eleverna delaktiga. Tekniken är en av artefakterna som möjliggör undervisningsformen och bidrar till en förändrad kommunikation. Flera av respondenterna i studien ser möjligheten till ett ökat lärande och upplever också att formativa bedömningsprocesser underlättas av undervisningsformen. / This study examines teachers’ experiences of Flipped Teaching. Two questions have been asked: What characterizes the Flipped Classroom? and What’s the purpose of Flipped Teaching? The theoretical framework is the sociocultural perspective by Vygotsky. The empirical material has been gathered through the qualitative interview and the method used to process the data has been the qualitative content analysis method. Nine teachers from various parts of southern Sweden have been interviewed. The two research questions resulted in eight categories, five from the first question: Changes in profession, Time, Key aspects – Participation, motivation and continuity, Tools involved and Communication with pupils. The second question generated three categories: Understanding preparatory, Visible learning and Access to the material. The results show that the teachers have become more guides on the side rather than lecturers and that time together with the students, interacting with them, has changed the ways of communication. The result also shows that the technical artefacts suports the Flipped Classroom, in some ways even as a conditional precedent for the Flipped Classroom. Many of the respondents in the study also express that the Flipped Classroom helps them assess the pupils’ abilities more formatively.
173

Modelling and optimisation of batch distillation involving esterification and hydrolysis reaction systems : modelling and optimisation of conventional and unconventional batch distillation process : application to esterification of methanol and ethanol using acetic acid and hydrolysis of methyl lactate system

Edreder, Elmahboub A. January 2010 (has links)
Batch distillation with chemical reaction when takes place in the same unit is referred to as batch reactive distillation process. The combination reduces the capital and operating costs considerably. Among many different types of batch reactive distillation column configurations, (a) conventional (b) inverted (c) semi-batch columns are considered here. Three reaction schemes such as (a) esterification of methanol (b) esterification of ethanol (c) hydrolysis of methyl lactate are studied here. Four different types of dynamic optimisation problems such as (a) maximum conversion (b) maximum productivity (c) maximum profit and (d) minimum time are formulated in this work. Optimal design and or operation policies are obtained for all the reaction schemes. A detailed rigorous dynamic model consisting of mass, energy balances, chemical reaction and thermodynamic properties is considered for the process. The model was incorporated within the dynamic optimisation problems. Control Vector Parameterisation (CVP) technique was used to convert the dynamic optimisation problem into a nonlinear programming problem which was solved using efficient SQP (Successive Quadratic Programming) method available within the gPROMS (general PROcess Modelling System) software. It is observed that multi-reflux ratio or linear reflux operation always led to better performance in terms of conversion, productivity for all reaction schemes compared to that obtained using single reflux operation. Feed dilution (in the case of ethanol esterification) led to more profit even though productivity was found to be lower. This was due to reduction in feed price because of feed dilution. Semi-batch reactive distillation opertation (for ethanol esterification) led to better conversion compared to conventional batch distillation, however, the total amount of acetic acid (reactant) was greater in semi-batch operation. Optimisation of design and operation (for ethanol esterification) clearly showed that a single cloumn will not lead to profitable operation for all possible product demand profile. Also change in feed and /or product price may lead to adjust the production target to maximise the profitability. In batch distillation, total reflux operation is recommended or observed at the begining of the operation (as is the case for methnaol or ethanol esterification). However, in the case of hydrolysis, total reflux operation was obseved at the end of the operation. This was due to lactic acid (being the heaviest) was withrawn as the final bottom product.
174

Contribution à l'étude des structures passives verre-silicium dans le domaine millimétrique / Contribution to the study of glass-silicon passive millimeter structures

Emond, Julien 02 July 2010 (has links)
Nous proposons dans cette thèse de nouvelles structures à faibles pertes en vue de leur utilisation dans les bandes millimétriques. L'hypothèse forte sur laquelle es t construite notre étude est que la présence du silicium permet d'envisager une intégration plus facile des circuits. Pour ce faire nous avons étudié les caractéristiques électriques des lignes inversées silicium-verre à 60 GHz ainsi que la ligne de Goubau sur silicium aux mêmes fréquences. Nous nous sommes focalisés sur l'étude des pertes des lignes. Les simulations présentées jusqu'à 60 GHz ont montré que les qualités de la technologie verre-silicium sont bonnes en termes de paramètres hyperfréquences. Nous proposons donc d'utiliser plutôt le verre pour la partie passive et le silicium pour la partie active. Nous montrons ainsi que cette technologie admet la réalisation des fonctions diverses et qu'elle est susceptible de permettre l'obtention de systèmes intégrés / We propose in this thesis several new structures with low loss for use in millimeter bands. The strong supposition with which is built our study is : the presence of silicon can be considered easier integration of circuits. That the reason why we have been studied the electrical characteristics of glass-silicon lines inverted at 60 GHz and the Goubau line on silicon with the same frequencies. We focus our attention on these studies of losses in lines. The simulations up to 60 GHz showed the qualities of the glass-silicon technology are good in terms of microwave parameters. So we propose to use glass for the passive and silicon for the active part. And we show that this technology allows the realization of various functions and is likely to allow the acquisition of integrated systems
175

Competition and Innovation: Revisiting the Relationship Using Alternative Measures of Rivalry

Astakhov, Anton January 2015 (has links)
This study re-examines the relationship between competition and innovation in a detailed firm-level dataset of publicly traded US companies spanning from 1975 to 2013. Using R&D expenditures, patent counts and patent citations as the measures of innovation, and Herfindahl-Hirschman Index, Lerner Index, Profit Elasticity and Product Market Fluidity as the proxies for competition we document a robust positive association between the two variables, as well as strong evidence of the non-linear relationship known as "inverted-U shape", when controlling for size, distance to technological frontier, level of knowledge spillovers, technological opportunities and other firm- and industry-specific characteristics. We address overdispersion in the data by using negative binomial and zero-inflated negative binomial count data regressions, and the results are robust in these specifications. Additionally, in order to address potential endogeneity issues, we employ a set of instruments based on the import tariff rates and the level of Chinese import penetration, and find a weak evidence of positive relationship as well. Overall the results strongly support the prediction of agency models, "replacement effect" and "escape- competition effect" about the positive influence of competition on innovation. Powered by TCPDF...
176

Construção, acionamento e ensaios do motor bifásico de imã permanente no rotor (MBIPR) / not available

Borelli, Rafael 10 June 2005 (has links)
Visando uma opção de substituição, onde for possível e aplicável, do motor de indução monofásico, este trabalho relata o estudo teórico, a construção, o acionamento e os ensaios de um motor bifásico com ímã permanente no rotor, de baixa potência, utilizando imãs de ferrita na confecção do rotor. / This work shows the theoretical studies, building, driving systems and tests of a small-power double-phase motor with ferrite permanent-magnet in the rotor, based on the original structure of a single-phase induction motor. The objective is to create an option to replace the single-phase induction motor where it is possible and applicable.
177

Filtragem e controle recursivos robustos aplicados em um pêndulo invertido / Robust recursive filter and control applied to an inverted pendulum

Ortega, Felix Mauricio Escalante 21 July 2016 (has links)
O estudo da estabilidade e desempenho em sistemas de controle é um tópico relevante na teoria de sistemas. Quando são assumidas incertezas no modelo da planta, existe uma maior dificuldade para garantir um nível de desempenho adequado do sistema dinâmico e a estabilidade pode ser comprometida. Neste trabalho são utilizados um regulador linear quadrático robusto e um filtro de Kalman robusto combinados em uma única formulação para tratar de sistemas dinâmicos incertos em tempo real. O caso de estudo selecionado é o pêndulo invertido. Seus principais desafios de controle encontrados na literatura: estabilização, seguimento e levantamento-captura, serão considerados. Os algoritmos utilizados são motivados pelo fato de que problemas estocásticos podem ser resolvidos por meio de argumentos determinísticos, baseados nos conceitos de função penalidade e mínimos quadrados regularizados. Desta forma, é possível a obtenção do melhor desempenho em contrapartida à máxima influência de incerteza admissível. A análise de desempenho do controlador robusto é realizada por meio de ensaios práticos incluindo incertezas na planta, ruído nos sensores e distúrbios no sinal de controle do pêndulo. / The study of stability and performance in control systems is a relevant topic in systems theory. When uncertainties are considered in the model of the plant, there is a greater difficulty in ensuring an appropriate performance level of the dynamic system, plus, the stability could be compromised as well. In this dissertation a robust linear quadratic regulator and a robust Kalman filter are used in a unified manner to deal with uncertain dynamic systems in real time. The selected case study is the inverted pendulum. Its main control challenges found in the literature will be considered: stabilization, tracking and catching swing-up. The used algorithms are motivated by the fact that stochastic problems can be solved through deterministic arguments based on the concepts of penalty function and regularized least-squares. Thus, it is possible to obtain an optimal performance for the maximum acceptable uncertainty. The performance analysis of the robust control is carried out by practical experiments including uncertainties in the plant, noise in the sensors and disturbance in the pendulum control signal.
178

Influência nas características do escoamento em função da alteração da geometria do conduto a jusante de válvula tipo segmento invertida em sistema de enchimento e esvaziamento de eclusas de navegação

Santos, Jessé Baptista Veronese dos 21 December 2012 (has links)
Submitted by Mariana Dornelles Vargas (marianadv) on 2015-04-09T18:40:24Z No. of bitstreams: 1 influencia_caracteristicas.pdf: 5180915 bytes, checksum: df667ffda685e6774d46e64735e32e82 (MD5) / Made available in DSpace on 2015-04-09T18:40:25Z (GMT). No. of bitstreams: 1 influencia_caracteristicas.pdf: 5180915 bytes, checksum: df667ffda685e6774d46e64735e32e82 (MD5) Previous issue date: 2012 / Nenhuma / Este trabalho apresenta um estudo de comportamento fluidodinâmico na operação de válvula do tipo segmento invertida, utilizadas em sistemas de enchimento e esvaziamento de navegação de eclusas. Nesta pesquisa é verificada a influência da alteração geométrica no conduto a jusante da comporta. O objetivo principal é encontrar dentre alterações geométricas aquela que oferece melhores condições de operação, isto é, minimizando os efeitos nocivos provocados pelas baixas pressões. O estudo é realizado através de abordagem numérica (CFD -Computer Fluid Dynamics), com o software comercial ANSYS-CFX, utilizando-se as equações da conservação da massa e quantidade de movimento como modelo básico. Foram simulados 3 comprimentos de expansão (Lexp = 0,3, 0,6 e 0,9 m) no teto a jusante da comporta, mantendo a mesma inclinação (1E:10 Lexp, onde E é a elevação do teto). Para cada comprimento de expansão foram simuladas 3 vazões (Q) e 3 aberturas (a), totalizando 27 simulações.As comparações entre os resultados numéricos para as expansões propostas são realizadas a partir do modelo numérico (original) já validado em trabalhos publicados. Também são feitas análises de parâmetros, como: alterações geométricas, pressões mínimas, regiões do conduto submetidas à pressões críticas (negativas), recuperação da pressão, coeficientes de perda de carga e de contração. Estas análises permitiram observar qual a influência da expansão no escoamento, mostrando que a simulação numérica pode ser utilizada como de apoio na definição de novas geometrias a serem adotadas nos projetos de novas eclusas, bem como na avaliação de eclusas já existentes identificando condições de operação nocivas na região junto a comporta. Verifica-se neste trabalho que as alterações geométricas propostas não são capazes de resolverem os problemas relativos às pressões negativas, e que seu desempenho depende das condições operação (principalmente a vazão). Contudo, quanto maiores forem as vazões, maiores serão as pressões mínimas obtidas com a expansão para o teto. Espera-se que os resultados obtidos possam ser usados como base para projetos, visando à diminuição dos efeitos nocivos na válvula (como cavitação, vibrações, erosões, ruídos e esforços espasmódicos) e perturbações que danificam as embarcações, durante a operação dentro da eclusa. / This paper presents a study of fluid dynamic behavior in the operation of inverted Tainter gate, used in filling and emptying systems of navigation locks. In this research is verified the influence of geometric change in the conduit downstream of the gate. The main objective is to find among geometric changes one that offers the best operating condition, i.e., minimizing the harmful effects of low pressures. The study is conducted through numerical approach (CFD-Computer Fluid Dynamics) with the commercial software ANSYS-CFX, using the equations of conservation of mass and momentum as the basic model. Were simulated 3 expansion lengths (Lexp = 0.3, 0.6 and 0.9 m) in the roof of downstream gate, keeping the same slope (1E:10 Lexp, where E is the elevation of the roof). For each expansion length were three simulated stream flow (Q) and 3 openings (a), totaling 27 numerical simulations. Comparisons between the numerical results for the proposed expansions are made from the numerical model (original) previously validated in published works. Also analysis are made of parameters such as geometric changes, minimum pressures, the conduit regions undergoing critical pressures (negative) pressure recovery, pressure loss and contraction coefficients. This analysis allowed observing the influence of the expansion in the flow, showing that the numerical simulation can be used to support the definition of new geometries to be adopted in the design of new navigation locks, as well as evaluation of existing locks, identifying the harmful operating conditions in the region near the gate. It is verified in this work that the geometric changes proposed are not able to solve the problems relating to negative pressures, and its performance depends on operating conditions (mainly the flow). However, the higher the flow rate, the greater the pressures obtained with minimal expansion to the roof. It is hoped that the results obtained can be used as a basis for projects in order to reduce the harmful effects on the valve (as cavitation, vibration, erosion, noise and spasmodic efforts) and disorders that damage the vessels, while operating within the lock.
179

Desconsideração da personalidade jurídica: limitações e aplicação no direito da família e sucessões / Disregard of legal entity: limitations and application on family and inheritance law.

Campos, Renato Luiz Franco de 12 February 2015 (has links)
O objetivo desta dissertação foi o estudo do instituto da desconsideração da personalidade jurídica, em sua modalidade inversa, e sua aplicabilidade no direito de família e sucessões, principalmente na partilha de bens - efetivada no divórcio ou dissolução de união estável -, na execução de alimentos e na sucessão legítima. A escolha do tema decorreu da necessidade do estabelecimento de pressupostos e requisitos objetivos para a aplicação da disregard na seara do direito de família e sucessões. A utilidade e adequação da abordagem da matéria se justifica pela instabilidade jurídica provocada pela acriteriosa aplicação da desconsideração da personalidade jurídica nas relações familiares. Por outro lado, o enfoque crítico desenvolvido no presente trabalho se justifica pela existência de corrente doutrinária que defende a aplicação da desconsideração em inúmeras situações familiares nas quais outros remédios, já seculares, de direito material ou processual seriam igualmente eficazes, sem que fosse necessária a drástica declaração de ineficácia da separação patrimonial entre a pessoa jurídica e seu sócio. Buscou-se apontar, desta forma, os meios existentes para se alcançar o mesmo resultado prático apresentado pela disregard, mas com a utilização de outras figuras, tais como a simulação, a fraude contra credores e a fraude à execução, ficando, por via de consequência, a aplicação da desconsideração da personalidade jurídica, restrita às hipóteses em que não há quaisquer outros meios para se evitar ou buscar a reparação dos prejuízos advindos da utilização das pessoas jurídicas com abuso da personalidade jurídica, desvio de finalidade ou confusão patrimonial. / The aim of this dissertation was the study of the doctrine of the disregard of legal entity, but in its inverted form, as well as its application to family law, particularly in the division of assets usually enforced in divorces and dissolution of stable union in alimony claims and inheritance law, specifically the forced heirship - legitimacy. The choice of this topic resulted from the necessity of stablishing objective assumptions and requirements for the application of the disregard doctrine to family and inheritance law. The utility and adequacy of the approach to this dissertation title is the legal instability generated by the inaccurate application of the disregard doctrine in family relationships. On the other hand, the critic approach developed over this dissertation is justified by the existence of positions sustained by renowned lawyers in the sense that the disregard doctrine may be applicable to family situations that should be, in fact, subjected to other existing remedies, without the Court interference declaring the void of the splitting of assets of the company and the assets of the shareholder. This dissertation intended to demonstrate the existing ways to have the same practical result eventually reached with the application of the disregard doctrine, using other figures such as sham, disguising and fraud, what makes the disregard doctrine restricted to cases in which there is no alternative other that its application to compensate damages resulted from the misuse or the abuse of legal entities.
180

Heurísticas para aprimorar o método BMW e suas variantes

Carvalho, Lídia Lizziane Serejo de 11 March 2015 (has links)
Submitted by Kamila Costa (kamilavasconceloscosta@gmail.com) on 2015-06-11T19:18:34Z No. of bitstreams: 1 Dissertação-Lídia L S de Carvalho.pdf: 837456 bytes, checksum: 620d89f05fc84dc2af7b89b6b6e587a0 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-06-15T17:53:19Z (GMT) No. of bitstreams: 1 Dissertação-Lídia L S de Carvalho.pdf: 837456 bytes, checksum: 620d89f05fc84dc2af7b89b6b6e587a0 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-06-15T17:57:19Z (GMT) No. of bitstreams: 1 Dissertação-Lídia L S de Carvalho.pdf: 837456 bytes, checksum: 620d89f05fc84dc2af7b89b6b6e587a0 (MD5) / Made available in DSpace on 2015-06-15T17:57:19Z (GMT). No. of bitstreams: 1 Dissertação-Lídia L S de Carvalho.pdf: 837456 bytes, checksum: 620d89f05fc84dc2af7b89b6b6e587a0 (MD5) Previous issue date: 2015-03-11 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Several research efforts have been conducted in the literature to develop methods to reduce the cost of query processing in search engines. This research aims to propose modifications to improve the performance of the block-Max WAND (BMW) algorithm, one of the most efficient algorithms proposed previously. The BMW algorithm uses heuristics to discard the documents entries at query processing, which makes it extremely fast. In this dissertation, we propose and evaluate additional heuristics to improve the perfomance of BMW and your variant BMW-CS in an attempt to both further reduces query processing times and the amount of memory required for processing queries. / Nos últimos anos, pesquisas relacionadas ao processamento de consultas em máquinas de busca têm sido realizadas com o objetivo de desenvolver métodos que reduzam o seu custo. Este trabalho visa propor modificações para melhorar o desempenho do algoritmo Block-Max WAND (BMW), um dos algoritmos mais eficientes propostos na literatura. O algoritmo BMW utiliza heurísticas para descartar documentos da resposta durante o processamento de consultas, o que torna sua execução extremamente veloz. Nesta dissertação, serão propostas e experimentadas modificações nas heurísticas de descarte de documentos e redução na quantidade de memória utilizada para processar consultas pelo algoritmo BMW e suas variantes, buscando-se assim ganhos de desempenho.

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