Thesis (M.A.)--University of California, 1914. / Bibliography: p. 119-122.

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2016-10-19T12:54:26Z No. of bitstreams: 1 PDF - Alexandre dos Santos Pascoal.pdf: 2352988 bytes, checksum: c311ea77167cf72630e47d718c89ef19 (MD5) / Approved for entry into archive by Secta BC (secta.csu.bc@uepb.edu.br) on 2016-10-19T17:11:33Z (GMT) No. of bitstreams: 1 PDF - Alexandre dos Santos Pascoal.pdf: 2352988 bytes, checksum: c311ea77167cf72630e47d718c89ef19 (MD5) / Made available in DSpace on 2016-10-19T17:11:34Z (GMT). No. of bitstreams: 1 PDF - Alexandre dos Santos Pascoal.pdf: 2352988 bytes, checksum: c311ea77167cf72630e47d718c89ef19 (MD5) Previous issue date: 2016-08-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / History and Philosophy of Science (HFC) has gained ground as an instrument to facilitate the teaching / learning for teachers and students of the sciences. This phenomenon can be explained by the degree of difficulty to explain / understand some scientific principles, when exposed out of context. The HFCs, to situate the scientific changes in the historical and philosophical context, at the same time it facilitates understanding, enables interdisciplinary practice in the academic environment. Our work is part of this new trend and the central idea was to create an innovative proposal of teaching from a problem that we see in the physical education field; the difficulty of understanding the Second Law of Thermodynamics. To this aim, starting from the HFC and the context of the Industrial Revolution, we conducted a literature search of exploratory and qualitative character on the subject and situate the importance of Carnot machine and its relation to our problem. As a result, in addition to academic text, we built a paradidactic and a proposal for practical application in the classroom and hope that these instruments contribute to the construction of an innovative teaching proposal. / A História e Filosofia da Ciência (HFC) tem ganhado espaço como um instrumento facilitador do processo de ensino/aprendizagem para professores e estudantes da área das ciências. Esse fenômeno pode ser explicado pelo grau de dificuldade encontrada para se explicar/entender alguns princípios científicos, quando expostos de maneira descontextualizada. A HFC, ao situar as mudanças científicas no contexto histórico e filosófico, ao mesmo tempo em que facilita o entendimento, possibilita a prática interdisciplinar no ambiente acadêmico. Nosso trabalho se insere nessa nova corrente e a ideia central foi à criação de uma proposta inovadora de ensino a partir de uma problemática que constatamos no campo do ensino da física; a dificuldade de compreensão da Segunda Lei da Termodinâmica. Para tal desiderato, partindo da HFC e do contexto da Revolução Industrial, realizamos uma pesquisa bibliográfica de caráter exploratória e qualitativa sobre a temática e situamos a importância da Máquina de Carnot e a relação desta com a nossa problemática. Como resultados, além do texto acadêmico, construímos um paradidático e uma proposta de aplicação prática em sala de aula e esperamos que estes instrumentos contribuam para a construção de uma proposta inovadora de ensino.

In this thesis, we will examine the properties of subelliptic jets in the Engel group of step 3. Step-2 groups, such as the Heisenberg group, do not provide insight into the general abstract calculations. This thesis then, is the first explicit non-trivial computation of the abstract results.

The Marnoch Heat Engine (MHE) is a recently patented type of new heat engine that produces electricity from lower temperature heat sources. The MHE utilizes lower temperature differences to generate electricity than any currently available conventional technologies. Heat can be recovered from a variety of sources to generate electricity, i.e., waste heat from thermal power plants, geothermal, or solar energy. This thesis examines the performance of an MHE demonstration unit, which uses air and a pneumatic piston assembly to convert mechanical flow work from pressure differences to electricity. This thesis finds that heat exchangers and the piston assembly do not need to be co-located, which allows benefits of positioning the heat exchangers in various configurations. This thesis presents a laboratory-scale, proof-of-concept device, which has been built and tested at the University of Ontario Institute of Technology, Canada. It also presents a thermodynamic analysis of the current system. Based on the MHE results, component modifications are made to improve the thermal performance and efficiency. The current configuration has an efficiency of about thirty percent of the maximum efficiency of a Carnot heat engine operating in the temperature range of 0oC to 100oC. The analysis and experimental studies allow future scale-up of the MHE into a pre-commercial facility for larger scale production of electricity from waste heat. / UOIT

La valorisation des rejets thermiques industriels par leur conversion en énergie mécanique, et éventuellement en électricité, est un moyen de réduire les émissions de gaz à effet de serre et de réduire la consommation énergétique des industries. La présente bourse de thèse est cofinancée par l’Agence De l’Environnement et de la Maitrise de l’Energie (ADEME) dans ce contexte. Le co-financeur de la thèse, Hevatech, est une entreprise qui exploite le brevet d’un nouveau convertisseur de chaleur en électricité appelé Turbosol®. Turbosol® est un bon candidat pour la valorisation de la chaleur fatale industrielle. Le concept en est au stade du développement du prototype et de l’installation de pilotes sur site. L’originalité du cycle de Turbosol® est la détente quasi-isotherme de la vapeur d’eau. Ainsi, le cycle de Turbosol® est proche du cycle de Carnot. La première partie de la thèse porte sur le cycle de Carnot et la faisabilité d’une machine fonctionnant selon le cycle de Carnot. Une machine fonctionnant selon le cycle de Carnot avec de l’eau changeant de phase pendant le chauffage est modélisée, puis optimisée par maximisation de la puissance nette produite. Les variables de l’optimisation sont les températures de vaporisation et de condensation du fluide cyclé, ainsi que la répartition de la surface d’échange entre l’évaporateur et le condenseur. Puis, dans la seconde partie, le modèle de la machine de Carnot est adapté au cas particulier de Turbosol®. Cela permet de simuler le fonctionnement du prototype de Turbosol. L’étude de sensibilité aux variables de commande du modèle a permis d’identifier la température de vaporisation et le débit massique du fluide de travail comme des variables d’optimisation. Ainsi, le convertisseur est optimisé par maximisation de la puissance nette produite et par maximisation du rendement pour un rejet thermique à valoriser donné / To convert the industrial waste heat into mechanical, or electrical energy, is a way to decrease the greenhouse gases emission and the energy consumption. The present PhD thesis is co-financed by the french Environment and Energy Management Agency (ADEME), in this context. The other co-financer, the company Hevatech, exploits the patent of a new heat converter into electricity named Turbosol®. Turbosol® is a good candidate for the industrial waste heat recovery. The concept is currently developed by the study of a prototype and the installation of the prototype on industrial site. The Turbosol® cycle originality is the quasi-isothermal expansion of the water vapor. Consequently, the Turbosol® cycle is close to the Carnot cycle. In the manuscript first part, the possibility of the feasibility of an engine operating according to the Carnot cycle is studied. A Carnot engine with a changing phase working fluid is modeled and optimized by maximization of the net power output. The variables are the optimal vaporization and condensation temperatures, and the optimal allocation of a total thermal transfer area between the condenser and the evaporator. Then, in the second part, the model of the Carnot engine is adapted to the Turbosol® prototype. In the sensitivity analysis, the vaporization temperature and the mass flow rate of the working fluid are identified as optimization variables. So, the Turbosol® converter is optimized by maximization of the net power output and the first law efficiency for a given waste heat fluid to valorize

Ce travail porte sur l'étude des propriétés optiques de l'oxyde de zinc (ZnO), matériau semi-conducteur à grand gap. La technique de caractérisation principale de ce travail est la spectroscopie par photoluminescence, technique non destructive permettant d'obtenir des informations relatives à la structure électronique d'un matériau. Après avoir présenté les propriétés du ZnO, de ses alliages, et rappelé quelques principes de base associés à la luminescence des matériaux semi-conducteurs., nous comparerons dans un premier temps les propriétés optiques de différents types de ZnO monocristallin, selon leur mode d'élaboration : matériaux massifs de différentes origines, couches épitaxiées et nanofils. Ces comparaisons ainsi que l'étude des effets sur les spectres de photoluminescence des traitements tels que recuit et passivation nous permettront d'avancer différentes hypothèses quant à l'origine de la luminescence visible dans ce matériau grand gap, sujet encore controversé dans la littérature. Dans un deuxième temps, nous présenterons notre contribution à l'étude du dopage p du matériau, qui est encore aujourd'hui le verrou pour l'obtention de diodes électroluminescentes à base de ZnO. Nous examinerons le problème du dopage intrinsèque de type n et de la compensation, préalable indispensable avant d'aborder le dopage de type p. Le dopage p est traité ici principalement au travers des études optiques d'échantillons implantés et recuits. Plusieurs variantes liées à l'implantation d'azote seront présentées et l'obtention de paires donneur accepteurs clairement mise en évidence pour des conditions de recuit optimisées. La nature des accepteurs présents est discutée par référence aux travaux antérieurs. . / We have studied the optical properties of Zinc Oxide (ZnO), a wide band gap semiconductor material. The main characterization technique used in this work is the photoluminescence spectroscopy, a non destructive technique which gives information about the electronic structure of the material. After presenting the properties of ZnO, its alloys, and reminding some basic principles relative to the luminescence in semiconductor materials, we will compare the optical properties of ZnO single-crystals from different growth methods: bulk material from different origins, epitaxial layers and nanowires. These comparisons and the effects of different treatments (annealing, passivation...) on the PL spectra unable us to emit hypothesis about the origin of the visible luminescence, which is a controversial subject in the literature. Secondly, we will present our contribution to the study of the p doping of ZnO, which is indispensable for device applications based on the p–n junction. We will take a look at the n type intrinsic doping problem before examining the p type doping. We investigate here p type doping through optical studies of implanted and annealed samples. We present here some variants of nitrogen implantation and the presence of donor acceptor pairs has been proven, leading to the optimization of the annealing conditions. Nature of the acceptors is discussed with the literature.

Este trabalho trata da questão de aprendizagem presente frequentemente entre estudantes do ensino médio e de um curso de Licenciatura em física: a dificuldade em empregar corretamente concepções científicas em questões que se referem a fenômenos termodinâmicos, mesmo tendo já passado pelo ensino desse conteúdo na escola. A pesquisa considera a importância de estabelecer conexões entre áreas de conhecimento complementares e essenciais para promover um ensino consistente; o resgate das raízes filosóficas da termodinâmica, fazendo emergir as estruturas que permitem a elaboração de seu arcabouço teórico em diferentes períodos históricos constitui uma base da pesquisa. Esse resgate nas aulas de física proporcionaria as condições para a emergência das potencialidades criativas dos sujeitos envolvidos no processo de ensino/aprendizagem e poderiam talvez possibilitar aos estudantes fazer uso dos conceitos científicos quando necessário. A análise das pesquisas de Kuhn sobre a conservação da energia e do conceito de obstáculo epistemológico de Bachelard reforçou nossa crença na importância de revolver o passado da ciência na busca das estruturas que sustentam a produção científica de uma época. Essas estruturas orientam a análise do corpus da pesquisa constituído pelas respostas escritas dos estudantes, para questões de termodinâmica e pelas ideias encontradas nos originais de Carnot e Clausius; o levantamento dos estruturantes, bem como as contribuições de outras pesquisas didáticas, resultam em subsídios relevantes para o planejamento de boas situações de ensino. Assim espera-se poder reverter as percepções prévias inadequadas dos estudantes em outras percepções mais amplas apoiadas nos princípios organizadores do conhecimento. / This work is concerned with a Physics learning problem that frequently appears both among secondary school students and also with scienc teaching students: the difficulty for adequately using Physics conceptions regarding to thermodynamics phenomena even after this content has been seen in their scholl activities. The research considers the importance of establishing connections between complementary knowledge areas that are essential for consistent teaching; a recall of the thermodynamical philosophical roots may favor the emergence of structures that have led to its theoretical framework in different historical periods and this has been taken as the basis for this research. This recall in Physics classes favors conditions for the emergence of a creative potential involved in the teaching/learning process and could perhaps enable students do use scientific concepts when necessary. The analysis of Kuhn\'s research on energy conservation and on Bachelard epistemological obstacle concept strengthened our belief on the importance of looking into the past of science in search of structures that sustain the scientific production of na epoch. These structures pointed towards an analysis of the research corpus a constituted by students answers and to thermodynamics questions found in Carnot\'s and Clausius\'s originals; the identification of such structures as well as work by other didactic research authors as relevant contributions for planning favorable teaching situations. Therefore it is expected that students inadequate previous conceptions may be reverted into broader perceptions based on knowledge organizing principles.

Este trabalho trata da questão de aprendizagem presente frequentemente entre estudantes do ensino médio e de um curso de Licenciatura em física: a dificuldade em empregar corretamente concepções científicas em questões que se referem a fenômenos termodinâmicos, mesmo tendo já passado pelo ensino desse conteúdo na escola. A pesquisa considera a importância de estabelecer conexões entre áreas de conhecimento complementares e essenciais para promover um ensino consistente; o resgate das raízes filosóficas da termodinâmica, fazendo emergir as estruturas que permitem a elaboração de seu arcabouço teórico em diferentes períodos históricos constitui uma base da pesquisa. Esse resgate nas aulas de física proporcionaria as condições para a emergência das potencialidades criativas dos sujeitos envolvidos no processo de ensino/aprendizagem e poderiam talvez possibilitar aos estudantes fazer uso dos conceitos científicos quando necessário. A análise das pesquisas de Kuhn sobre a conservação da energia e do conceito de obstáculo epistemológico de Bachelard reforçou nossa crença na importância de revolver o passado da ciência na busca das estruturas que sustentam a produção científica de uma época. Essas estruturas orientam a análise do corpus da pesquisa constituído pelas respostas escritas dos estudantes, para questões de termodinâmica e pelas ideias encontradas nos originais de Carnot e Clausius; o levantamento dos estruturantes, bem como as contribuições de outras pesquisas didáticas, resultam em subsídios relevantes para o planejamento de boas situações de ensino. Assim espera-se poder reverter as percepções prévias inadequadas dos estudantes em outras percepções mais amplas apoiadas nos princípios organizadores do conhecimento. / This work is concerned with a Physics learning problem that frequently appears both among secondary school students and also with scienc teaching students: the difficulty for adequately using Physics conceptions regarding to thermodynamics phenomena even after this content has been seen in their scholl activities. The research considers the importance of establishing connections between complementary knowledge areas that are essential for consistent teaching; a recall of the thermodynamical philosophical roots may favor the emergence of structures that have led to its theoretical framework in different historical periods and this has been taken as the basis for this research. This recall in Physics classes favors conditions for the emergence of a creative potential involved in the teaching/learning process and could perhaps enable students do use scientific concepts when necessary. The analysis of Kuhn\'s research on energy conservation and on Bachelard epistemological obstacle concept strengthened our belief on the importance of looking into the past of science in search of structures that sustain the scientific production of na epoch. These structures pointed towards an analysis of the research corpus a constituted by students answers and to thermodynamics questions found in Carnot\'s and Clausius\'s originals; the identification of such structures as well as work by other didactic research authors as relevant contributions for planning favorable teaching situations. Therefore it is expected that students inadequate previous conceptions may be reverted into broader perceptions based on knowledge organizing principles.

The object of this thesis is a graphic based interface to endoreversible thermodynamics. It is meant to enable the user to visually create endoreversible systems and add the properties of the system by choosing features from a list and in form of equations. Then an equation system is built and the power output and efficiency of the endoreversible system is calculated and plotted. To illustrate the functions of the interface, some examples of heat and chemical engines are discussed.

In this Ph.D. thesis we discuss results concerning variational convergences for functionals and differential operators on Lipschitz continuous vector fields. The convergences taken into account are gamma-convergence (for functionals) and H-convergence (for differential operators).