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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.
11

Brahms and the Character Piece: Emotion Guided by Intellect, a Lecture Recital, Together with Three Recitals of Selected Compositions by Beethoven, Brahms, Chopin, Debussy, Mozart, Prokofieff, and Ravel

Blocker, Robert L. (Robert Lewis), 1946- 12 1900 (has links)
The lecture recital was given October 15, 1971. The subject of the discussion was Brahms and the Character Piece: Emotion Guided by Intellect, and it included historical and biographical information, an analysis of Brahms' romantic-classic style, a general analysis of the six character pieces in Opus 118, and performance of Opus 118 by memory. In addition to the lecture recital, three other public recitals were performed. These three programs were comprised of solo literature for the piano. The first solo recital was on April 15, 1971, and included works of Brahms, Chopin, Mozart, and Ravel. The second program, presented on April 28, 1972, featured several works of Beethoven. Performed on Septemhber 25, 1972, the third recital programmed compositions by Chopin, Debussy, and Prokofieff. Magnetic tape recordings of all four programs and the written lecture material are filed together as the dissertation.
12

Acordo de voto: elementos e vinculação / Voting agreements: elements and binding effects.

Carvalho, Eduardo Henrique Pinto de 27 May 2013 (has links)
Esta dissertação procura analisar os acordos de acionistas tipificados pelo art. 118 da Lei nº 6.404/76, mais especificamente, os acordos que regulam o exercício do voto e/ou o exercício do poder de controle. O interesse pelo tema é decorrente da falta de consenso da doutrina e da jurisprudência acerca do assunto, o que contribuiu fortemente para a insegurança jurídica no uso do instituto. Além disso, tal falta de consenso foi acentuada com a reforma da lei acionária pela Lei nº 10.303/01. Dessa forma, o presente trabalho busca, a partir da análise da doutrina pátria e da doutrina estrangeira, delimitar corretamente os principais conceitos acerca do acordo de voto. Com este objetivo, o presente trabalho começa com a análise das características históricas das sociedades anônimas, focada na definição de competência e interação entre os órgãos da companhia, resultando na conclusão de que no direito brasileiro, não há uma divisão fixa de competências entre os órgãos e há hierarquia entre tais órgãos, prevalecendo a assembleia geral de acionistas. Nos demais capítulos, o presente trabalho analisa: (a) o conceito de partes, estabelecendo que apenas acionistas podem ser partes em acordo de votos, (b) o objeto, reconhecendo o exercício do direito de voto e o exercício do poder de controle como objetos legítimos, admitindo-se assim a diferenciação entre acordo de comando e acordo de defesa, (c) as delimitações do objeto, demonstrando que interesse social e abuso de poder de controle são dois fortes delineadores do conteúdo dos acordos de voto, e (d) os efeitos dos acordos de voto, especificamente os acordos de defesa e os acordos de comando, vez que podem irradiar efeitos para os órgãos administrativos da companhia. Espera-se que este trabalho possa contribuir com o debate acerca do tema acordo de voto. / This dissertation endeavors an investigation on shareholders agreements set forth by Article 118 of Federal Law N. 6,404/76, more precisely, shareholders agreements that regulates the exercise of voting rights and/or the control over the company. The interest for the subject developed in view of the nonexistence of an agreement on the matter, either by the legal doctrine or the case law. Furthermore, the dissensions were heightened by the modifications Federal Law N. 10,303/01 implemented to Federal Law N. 6,404/76. In this sense, the present study pursues to correctly circumscribe the main concepts regarding voting agreements, through an analysis of Brazilian and foreign legal doctrine. With such purpose, this work starts with an examination of historical characteristics of joint-stock corporations, focusing on the definition of the powers regarding each body of the company, and on the interaction between them, coming to the conclusion that, under Brazilian law, there is no fixed partition of powers between the bodies, but there is hierarchy between them, being the shareholders meeting the prevalent body. Moreover, this dissertation investigates: (a) the concept of parties, concluding that only shareholders can be parties in voting agreements; (b) the object of shareholders agreements, recognizing the exercise of voting rights and the control over the company as lawful objects, acknowledging, therefore, the difference between commanding agreements and defense agreements; (c) the delimitations of the object, demonstrating that social interest and abuse of control over the company are two main aspects that bound the content of voting agreements; and (d) the effects of shareholders agreements, more specifically, the commanding agreements and defense agreements, considering that they may be effective over administrative bodies of the company. This work is expected to contribute with the debate regarding the matter on voting agreements.
13

Finite difference methods for the advection equation / Peter John Steinle

Steinle, Peter John January 1993 (has links)
Bibliography : leaves 211-216 / 216 leaves : ill ; 20 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied Mathematics, 1994?
14

Attenuation Of Polychlorinated Biphenyls Under Anaerobic Conditions

Kaya, Devrim 01 September 2012 (has links) (PDF)
Polychlorinated biphenyls (PCBs) are toxic and persistent anthropogenic contaminants. Concern on their adverse health effects has led to their regulation in air, water and/or soil in addition to sludge. Hence, removal of PCBs in various matrices, including transformer oils (TO) is a priority. This study aims to investigate PCB-118 and Aroclor 1254 toxicity and dechlorination by varying certain critical experimental components including electron donor (sludge or fatty acids), inocula (unacclimated or acclimated culture) and the doses of PCB and TO under anaerobic conditions. Anaerobic toxicity assays (ATA) reactors, lab-scale anaerobic batch digesters and sediment microcosms were used for this purpose. Increase in PCB-118 and TO doses affected anaerobic digester performance by negatively influencing methanogenesis, while favoring dechlorination only with the increase in PCB-118 dose. Up to 22% PCB-118 removal was attained with unacclimated culture. Studies with acclimated cultures showed Grasse River (GR) sediment to be the most active when compared to Fox River and Baltimore Harbor sediments. In GR sediment microcosms, PCB-118 and Aroclor 1254 removal efficiencies decreased when TO was present (1%), while 10% TO inhibited PCB dechlorination. Waste activated sludge was shown to be an effective electron donor, similar to fatty acids. Aroclor 1254 dechlorination was dechlorinated through removal of flanked meta and para chlorines, however, dechlorination pathways appeared to differ according to the presence/absence of TO. No ortho or unflanked chlorines were removed. Molecular tools (qPCR and DHPLC) were used to confirm the presence of active PCB dechlorinators. Dechlorination of PCBs was shown to be growth-linked.
15

Avaliação da atividade e mecanismo de ação da LQB-118 em leishmania amazonensis

Cunha Júnior, Edézio Ferreira January 2011 (has links)
Submitted by Anderson Silva (avargas@icict.fiocruz.br) on 2012-11-27T11:46:56Z No. of bitstreams: 1 edezio_f_cunhajunior_ioc_bcm_0046_2011.pdf: 1328543 bytes, checksum: 6f45369f40d42516302f4eecaec5409c (MD5) / Made available in DSpace on 2012-11-27T11:46:56Z (GMT). No. of bitstreams: 1 edezio_f_cunhajunior_ioc_bcm_0046_2011.pdf: 1328543 bytes, checksum: 6f45369f40d42516302f4eecaec5409c (MD5) Previous issue date: 2011 / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil. / A leishmaniose é, ainda hoje, uma doença negligenciada, estando entre os agravos prioritários do programe de pesquisa sobre doenças da pobreza da Organização Mundial da Saúde (TDR/OMS). Além de não haver vacinas disponíveis, a terapia é baseada em medicamentos injetáveis que causam sérios efeitos colaterais, tornando o tratamento inviável para muitos países endêmicos. Fica evidente, então, a necessidade e urgência do desenvolvimento de novos medicamentos eficazes, seletivos, de baixo custo e, de preferência, de administração oral. A LQB-118 e seus análogos surgiram da união de dois grupos de moléculas bioativas, os pterocarpanos e as quinonas, formando as naftopterocarpanoquinonas, que vem demonstrando atividade leishmanicida. Neste trabalho avaliamos a atividade in vitro e in vivo do protótipo mais promissor. A LQB-118 demonstrou atividade leishmanicida em promastigotas de diferentes espécies de Leishmania, tanto do novo mundo como do velho mundo. No tratamento da leishmaniose cutânea em modelo murino, mostrou-se eficaz, tanto no tratamento subcutâneo por vias de administração sistêmica, oral e intraperitoneal. Ensaios bioquímicos indicaram que a LQB-118 induz um aumento expressivo da atividade de redutases mitocondriais nas primeiras horas, com concomitante aumento da produção de espécies reativas de oxigênio (ERO) pelos parasitos. Juntos, esses resultados indicaram que a LQB-118 é um protótipo seletivo, atuando primariamente sobre a mitocôndria dos parasitos, com atividade in vivo por via oral, o que a credencia como uma potencial candidata a fármaco.(AU) / Leishmaniasis is still today a neglected disease, and it is among the priorities of the research program on diseases of poverty of World Health Organization (TDR/WHO). There is no available vaccine and the treatment is based on injectable drugs that cause serious side effects, which is unaffordable for several endemic countries. It is evident, then, the need and urgency of developing new selective, inexpensive, effective drugs, preferably orally delivered. LQB-118 and its analogues have emerged from the union of two groups of bioactive molecules, pterocarpans and quinones, forming the naphthopterocarpanoquinones, which have shown leishmanicidal activity. In this study, the in vitro and in vivo activity of the most promising prototype is demonstrated. The LQB-118 showed antileishmanial activity in promastigotes of different species of Leishmania, both of new as the old world. LQB-118 has shown to be effective in treatment of cutaneous leishmaniasis in a murine model by subcutaneous, oral, and intraperitoneal routes. Biochemical assays indicate that the LQB-118 induces an expressive enhancement of mitochondrial reductases activity in the early hours of incubation, which is paralleled with enhancement of reactive oxygen species (ROS) production by the parasites. Altogether, these results indicate that LQB-118 is a selective lead compound, acting primarily on the parasite mitochondria, orally active in murine model, what qualifies it as a potential drug candidate.
16

Acordo de voto: elementos e vinculação / Voting agreements: elements and binding effects.

Eduardo Henrique Pinto de Carvalho 27 May 2013 (has links)
Esta dissertação procura analisar os acordos de acionistas tipificados pelo art. 118 da Lei nº 6.404/76, mais especificamente, os acordos que regulam o exercício do voto e/ou o exercício do poder de controle. O interesse pelo tema é decorrente da falta de consenso da doutrina e da jurisprudência acerca do assunto, o que contribuiu fortemente para a insegurança jurídica no uso do instituto. Além disso, tal falta de consenso foi acentuada com a reforma da lei acionária pela Lei nº 10.303/01. Dessa forma, o presente trabalho busca, a partir da análise da doutrina pátria e da doutrina estrangeira, delimitar corretamente os principais conceitos acerca do acordo de voto. Com este objetivo, o presente trabalho começa com a análise das características históricas das sociedades anônimas, focada na definição de competência e interação entre os órgãos da companhia, resultando na conclusão de que no direito brasileiro, não há uma divisão fixa de competências entre os órgãos e há hierarquia entre tais órgãos, prevalecendo a assembleia geral de acionistas. Nos demais capítulos, o presente trabalho analisa: (a) o conceito de partes, estabelecendo que apenas acionistas podem ser partes em acordo de votos, (b) o objeto, reconhecendo o exercício do direito de voto e o exercício do poder de controle como objetos legítimos, admitindo-se assim a diferenciação entre acordo de comando e acordo de defesa, (c) as delimitações do objeto, demonstrando que interesse social e abuso de poder de controle são dois fortes delineadores do conteúdo dos acordos de voto, e (d) os efeitos dos acordos de voto, especificamente os acordos de defesa e os acordos de comando, vez que podem irradiar efeitos para os órgãos administrativos da companhia. Espera-se que este trabalho possa contribuir com o debate acerca do tema acordo de voto. / This dissertation endeavors an investigation on shareholders agreements set forth by Article 118 of Federal Law N. 6,404/76, more precisely, shareholders agreements that regulates the exercise of voting rights and/or the control over the company. The interest for the subject developed in view of the nonexistence of an agreement on the matter, either by the legal doctrine or the case law. Furthermore, the dissensions were heightened by the modifications Federal Law N. 10,303/01 implemented to Federal Law N. 6,404/76. In this sense, the present study pursues to correctly circumscribe the main concepts regarding voting agreements, through an analysis of Brazilian and foreign legal doctrine. With such purpose, this work starts with an examination of historical characteristics of joint-stock corporations, focusing on the definition of the powers regarding each body of the company, and on the interaction between them, coming to the conclusion that, under Brazilian law, there is no fixed partition of powers between the bodies, but there is hierarchy between them, being the shareholders meeting the prevalent body. Moreover, this dissertation investigates: (a) the concept of parties, concluding that only shareholders can be parties in voting agreements; (b) the object of shareholders agreements, recognizing the exercise of voting rights and the control over the company as lawful objects, acknowledging, therefore, the difference between commanding agreements and defense agreements; (c) the delimitations of the object, demonstrating that social interest and abuse of control over the company are two main aspects that bound the content of voting agreements; and (d) the effects of shareholders agreements, more specifically, the commanding agreements and defense agreements, considering that they may be effective over administrative bodies of the company. This work is expected to contribute with the debate regarding the matter on voting agreements.
17

The reception of Psalm 118 in the New Testament : application of a “New Exodus Motif”?

Kwon, Hyukjung 17 October 2007 (has links)
Please read the abstract in the section 00front of this document / Thesis (PhD (New Testament Studies))--University of Pretoria, 2007. / New Testament Studies / PhD / unrestricted
18

Proposta e implementação de uma Micro-PMU

Aleixo, Renato Ribeiro 01 March 2018 (has links)
Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-04-10T14:04:24Z No. of bitstreams: 1 renatoribeiroaleixo.pdf: 11717772 bytes, checksum: 92418eff47ec8bfa0e099a19d849c068 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-04-10T14:22:50Z (GMT) No. of bitstreams: 1 renatoribeiroaleixo.pdf: 11717772 bytes, checksum: 92418eff47ec8bfa0e099a19d849c068 (MD5) / Made available in DSpace on 2018-04-10T14:22:50Z (GMT). No. of bitstreams: 1 renatoribeiroaleixo.pdf: 11717772 bytes, checksum: 92418eff47ec8bfa0e099a19d849c068 (MD5) Previous issue date: 2018-03-01 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho tem como objetivo a proposta de uma Unidade de Medição Fasorial (do inglês, Phasor Measurement Unit)(PMU), de baixo custo, voltada para o monito-ramento da distribuição de energia elétrica. O medidor proposto pode ser conectado à rede de baixa tensão, possibilitando assim o monitoramento dos sistemas de dis-tribuição e transmissão de energia. O algoritmo de estimação fasorial que compõe o software embarcado do equipamento faz uso do filtro Savitzky-Golay como aproxima-ção da derivada, necessária no processo de estimação da frequência do componente fundamental do sinal. O hardware utilizado é composto pelo microprocessador ARM TM4C1294NCPDT da Texas Instruments, um módulo GPS NEO-6M da uBlox, um módulo Wi-Fi ESP8266, além de um circuito de condicionamento do sinal analógico. O sincronismo das medições realizadas é garantido graças ao sinal composto por um pulso por segundo fornecido pelo GPS. Para o envio dos dados gerados pelo medidor pro-posto, o protocolo definido na norma vigente para PMUs foi utilizado. As estimações podem ser armazenadas e vizualizadas em tempo real através de um software monitor de dados de sincrofasores. Os resultados contemplam os testes exigidos pela norma, avaliando-se o erro total da estimação do fasor, o erro de frequência e o erro de taxa de variação da frequência. Por último, a fim de se reafirmar o sincronismo existente entre as medições realizadas por mais de um equipamento, estimou-se os fasores e a frequência em pontos distintos do sistema 4 Barras do IEEE, simulado em tempo real no RTDS, onde pode-se observar a estimação correta da defasagem entre duas barras desse sistema. / The present work proposes of a low cost Phasor Measurement Unity (PMU), for monitoring the power distribution system. The proposed meter can be connected at the low voltage level, making possible the monitoring of the distribution system and the transmission system. The algorithm used to compute the phasor estimation that composes the embedded software in the equipment uses the Savitzky-Golay filter to approximate the differentiation process, necessary in the frequency estimation of the fundamental component of the signal. The hardware of the equipment is composed by a microprocessor AMR TM4C1294NCPDT of Texas Instruments, a uBlox GPS NEO-6M module, a Wi-Fi ESP8266 module and an analog conditioning circuit. The synchronism of the measurements is guaranteed due to a pulse per second signal from the GPS module. For the transmission of the data generated by the PMU, the protocol suggested by the standard is used. The estimated parameters can be visualized in real time through the Synchrophasor Data Monitor Software. The results contemplate the tests required by the IEEE standard C37.118.1 and the analyses of the total vector error, frequency error and rate of change of frequency error. Finally, to attest the synchronism between different PMUs, a test in a Real Time Digital Simulator (RTDS) was made, where the 4 bus IEEE system was simulated. The difference of the angles estimated for different buses was computed and the obtained values were according to the expected.
19

Model Based Design of a Magnetoelectric Vibration Converter from Weak Kinetic Sources

Naifar, Slim 04 March 2019 (has links)
The main challenge in the design of vibration energy harvesters is the optimization of energy outcome relative to the applied excitation to reach a higher efficiency in spite of the weakness of ambient energy sources. One promising principle of vibration converters is magnetoelectricity due to the outstanding properties of magnetostrictive and piezoelectric laminate composites, which provide interesting possibilities to harvest energy from low amplitude and low frequency vibration with relatively high energy outcome. For these devices, ensuring high deformations in the magnetostricive layers, improvement of the magnto-mechanical and the electro-mechanical couplings are highly required for the optimization of the energy outcome. This thesis primarily aims to develop a model based harvester design for magnetoelectric (ME) converters. Based on a comprehensive understanding of the complex energy flow in magnetoelectric transducers, several design parameters are investigated. For instance, magnetostriction in a Terfenol-D plate is investigated by means of atomic force microscopy under similar conditions as within magnetoelectric transducers. A novel measurement approach was successfully developed to detect the evolution of magnetic domains and measure deformations in a Terfenol-D plate in response to externally non-uniform applied magnetic fields. Furthermore, a finite element model is developed to predict the induced voltage in the ME transducer as a response to the magnet’s displacement, corrected based on atomic force microscopy measurements, and used for the design of the harvester. The presented three- dimensional model takes into consideration the nonlinear behaviour of the magnetostrictive and piezoelectric materials. Additionally, three novel converters having different magnetic circuits are designed and analysed analytically based on Lindstedt-Poincaré method. The effects of the structure parameters, such as the nonlinear magnetic forces, the magnetic field distribution and the resonance frequency are discussed, and the electric output performances of the three designed converters are evaluated. In order to improve both mechanical and electrical coupling between the piezoelectric and the magnetostrictive layers, a bonding technique at room temperature is proposed which uses conductive polymer nanocomposites. Two magnetoelectric transducers are fabricated based on this technique having 1 wt.% and 2 wt.% concentration of multiwalled carbon nanotubes in epoxy resin. Another magnetoelectric transducer is fabricated by a classical technique for comparison purposes. In order to validate the design, a series of demonstrators are designed and fabricated according to the simulation and optimization results. The proposed design is composed by a cantilever beam, a magnetic circuit with several magnet arrangements and a magnetoelectric transducer, which is formed by a piezoelectric PMNT plate bonded to two magnetostrictive Terfenol-D layers. In this design, external vibrations are converted to magnetic field changes acting on the magnetostrictive layers leading to deformations, which are transmitted directly to the piezoelectric layer. The converters are tested under harmonic excitations and real vibration profiles reproduced by an artificial vibration source. Different parameters were investigated experimentally including the magnetic forces between the transducer and the magnetic circuit and the used bonding technique. Tuning the resonance frequency of the ME converter is also addressed using a simple screw/nut system, which allows to control the relative position and therefore the magnetic forces between the magnetic circuit and the transducer. The magnetoelectric transducer bonded with 2 wt.% concentration of multiwalled carbon nanotubes shows better output performances than the two other ME transducers under similar excitations. A maximum power output of 2.42 mW is reached under 1 mm applied vibration at 40 Hz. This performance presents an improvement of minimum 20 % of the reached energy outcome by other magnetoelectric vibration converters using single ME transducer at comparable applied excitations. / Die größte Herausforderung bei der Konstruktion von Vibrations-Energiewandlern ist die Optimierung der gewonnenen Energie im Verhältnis zur angewandten Anregung, um trotz schwacher Umgebungsenergiequellen einen hohen Wirkungsgrad zu erreichen. Ein vielversprechendes Prinzip von Vibrationswandlern ist die Magnetoelektrizität aufgrund der hervorragenden Eigenschaften von magnetostriktiven und piezoelektrischen Verbundwerkstoffen, die interessante Möglichkeiten bieten, Energie aus niederfrequenten Schwingungen mit kleinen Amplituden zu gewinnen. Bei diesen Wandlern ist die Sicherstellung hoher Verformungen in den magnetostriktiven Schichten, die Verbesserung der magnetisch-mechanischen und der elektromechanischen Kopplungen für die Optimierung des Energieertrages sehr wichtig. Diese Arbeit zielt in erster Linie auf die Entwicklung eines modellbasierten Entwurfs für magnetoelektrische (ME) Wandler ab. Basierend auf einem umfassenden Verständnis des komplexen Energieflusses in magnetoelektrischen Wandlern werden mehrere Entwurfsparameter untersucht. So wird beispielsweise die Magnetostriktion in einer Terfenol-D-Platte mittels Rasterkraftmikroskopie unter ähnlichen Bedingungen untersucht wie in magnetoelektrischen Wandlern. Dabei wurde eine neuartige Messmethode erfolgreich entwickelt, um die Entwicklung von magnetischen Domänen zu erfassen und die Deformation in einer Terfenol-D-Platte als Reaktion auf extern ungleichmäßig angelegte Magnetfelder zu messen. Darüber hinaus wird ein Finite-Elemente-Modell entwickelt, um die induzierte Spannung im ME-Wandler als Reaktion auf die Verschiebung des Magneten vorherzusagen, welches auf der Grundlage von Atomkraftmikroskopie Messungen korrigiert und für den Entwurf des Energiewandlers verwendet wird. Das vorgestellte dreidimensionale Modell berücksichtigt das nichtlineare Verhalten der magnetostriktiven und piezoelektrischen Materialien. Zusätzlich werden drei neuartige Wandler mit unterschiedlichen Magnetkreisen nach dem Lindstedt-Poincaré Verfahren konzipiert und analytisch analysiert. Die Auswirkungen der Strukturparameter, wie die nichtlinearen Magnetkräfte, die Magnetfeldverteilung und die Resonanzfrequenz, werden diskutiert und die elektrischen Ausgangsleistungen der drei ausgelegten Wandler ausgewertet. Um die mechanische und elektrische Kopplung zwischen der piezoelektrischen und der magnetostriktiven Schicht zu verbessern, wird eine bei Raumtemperatur prozessierbare Verbindungstechnik vorgeschlagen, bei der leitfähige Nanokomposite verwendet werden. Zwei magnetoelektrische Wandler werden basierend auf dieser Technik mit einer Konzentration von 1 wt.% und 2 wt.% an mehrwandigen Kohlenstoff-Nanoröhren in Epoxidharz hergestellt. Ein weiterer magnetoelektrischer Wandler wurde zu Vergleichszwecken mit einer klassischen Technik hergestellt. Für die Validierung des Entwurfes wird eine Reihe von Demonstratoren entsprechend den Simulations- und Optimierungsergebnissen konstruiert und gefertigt. Der vorgeschlagene Entwurf besteht aus einem Trägerbalken, einem Magnetkreis mit mehreren Magnetanordnungen und einem magnetoelektrischen Wandler, der aus einer piezoelektrischen PMNT-Platte besteht, die mit zwei magnetostriktiven Terfenol-D-Schichten verbunden ist. Bei dieser Konstruktion werden externe Schwingungen in Magnetfeldänderungen umgewandelt, die auf die magnetostriktiven Schichten wirken und zu Verformungen führen, die direkt auf die piezoelektrische Schicht übertragen werden. Die Wandler werden unter harmonischen Anregungen und mit realen Schwingungsprofilen getestet, die von einer künstlichen Schwingungsquelle reproduziert werden. Verschiedene Parameter wurden experimentell untersucht, darunter die magnetischen Kräfte zwischen dem Wandler und dem Magnetkreis sowie die verwendete Verbindungstechnik. Die Abstimmung der Resonanzfrequenz des ME-Wandlers erfolgt ebenfalls über ein einfaches Schrauben-Mutter-System, das es ermöglicht, die relative Position und damit die magnetischen Kräfte zwischen Magnetkreis und Wandler zu steuern. Der magnetoelektrische Wandler, der mit einer Konzentration von 2 wt.% mehrwandiger Kohlenstoff-Nanoröhrchen verbunden ist, zeigt bessere Ausgangsleistungen als die beiden anderen ME-Wandler bei ähnlichen Anregungen. Eine maximale Ausgangsleistung von 2,42 mW wird bei 1 mm angelegter Vibration bei 40 Hz erreicht. Diese Leistung stellt eine Verbesserung von mindestens 20 % im Vergleich zu anderen magnetoelektrischen Schwingungsumrichtern dar, welche mit einem einzigen ME-Wandler bei vergleichbaren Anregungen getestet werden.
20

Continuous formulation of implicit structural modeling discretized with mesh reduction methods / Formulation continue du problème de modélisation implicite de structures géologiques discrétisée avec des méthodes de réduction de maillage

Renaudeau, Julien 24 April 2019 (has links)
La modélisation structurale consiste à approximer les structures géologiques du sous-sol en un modèle numérique afin d'en visualiser la géométrie et d'y effectuer des calculs d'estimation et de prédiction. L'approche implicite de la modélisation structurale utilise des données de terrain interprétées pour construire une fonction volumétrique sur le domaine d'étude qui représente la géologie. Cette fonction doit honorer les observations, interpoler entre ces dernières, et extrapoler dans les zones sous-échantillonnées tout en respectant les concepts géologiques. Les méthodes actuelles portent cette interpolation soit sur les données, soit sur un maillage. Ensuite, le problème de modélisation est posé selon la discrétisation choisie : par krigeage dual sur les points de donnée ou en définissant un critère de rugosité sur les éléments du maillage. Dans cette thèse, nous proposons une formulation continue de la modélisation structurale par méthodes implicites. Cette dernière consiste à minimiser une somme de fonctionnelles arbitraires. Les contraintes de donnée sont imposées avec des fonctionnelles discrètes, et l'interpolation est contrôlée par des fonctionnelles continues. Cette approche permet de (i) développer des liens entre les méthodes existantes, (ii) suggérer de nouvelles discrétisations d'un même problème de modélisation, et (iii) modifier le problème de modélisation pour mieux honorer certains cas géologiques sans dépendre de la discrétisation. Nous portons également une attention particulière à la gestion des discontinuités telles que les failles et les discordances. Les méthodes existantes nécessitent soit la création de zones volumétriques avec des géométries complexes, soit la génération d'un maillage volumétrique dont les éléments sont conformes aux surfaces de discontinuité. Nous montrons, en explorant des méthodes sans maillage locales et des concepts de réduction de maillage, qu'il est possible d'assurer l'interpolation des structures tout en réduisant les contraintes liées à la gestion des discontinuités. Deux discrétisations de notre problème de minimisation sont suggérées : l'une utilise les moindres carrés glissants avec des critères optiques pour la gestion des discontinuités, et l'autre utilise des fonctions issues de la méthode des éléments finis avec le concept de nœuds fantômes pour les discontinuités. Une étude de sensibilité et une comparaison des deux méthodes sont proposées en 2D, ainsi que quelques exemples en 3D. Les méthodes développées dans cette thèse ont un grand impact en termes d'efficacité numérique et de gestion de cas géologiques complexes. Par exemple, il est montré que notre problème de minimisation au sens large apporte plusieurs solutions pour la gestion de cas de plis sous-échantillonnés et de variations d'épaisseur dans les couches stratigraphiques. D'autres applications sont également présentées tels que la modélisation d'enveloppe de sel et la restauration mécanique. / Implicit structural modeling consists in approximating geological structures into a numerical model for visualization, estimations, and predictions. It uses numerical data interpreted from the field to construct a volumetric function on the domain of study that represents the geology. The function must fit the observations, interpolate in between, and extrapolate where data are missing while honoring the geological concepts. Current methods support this interpolation either with the data themselves or using a mesh. Then, the modeling problem is posed depending on these discretizations: performing a dual kriging between data points or defining a roughness criterion on the mesh elements. In this thesis, we propose a continuous formulation of implicit structural modeling as a minimization of a sum of generic functionals. The data constraints are enforced by discrete functionals, and the interpolation is controlled by continuous functionals. This approach enables to (i) develop links between the existing methods, (ii) suggest new discretizations of the same modeling problem, and (iii) modify the minimization problem to fit specific geological issues without any dependency on the discretization. Another focus of this thesis is the efficient handling of discontinuities, such as faults and unconformities. Existing methods require either to define volumetric zones with complex geometries, or to mesh volumes with conformal elements to the discontinuity surfaces. We show, by investigating local meshless functions and mesh reduction concepts, that it is possible to reduce the constraints related to the discontinuities while performing the interpolation. Two discretizations of the minimization problem are then suggested: one using the moving least squares functions with optic criteria to handle discontinuities, and the other using the finite element method functions with the concept of ghost nodes for the discontinuities. A sensitivity analysis and a comparison study of both methods are performed in 2D, with some examples in 3D. The developed methods in this thesis prove to have a great impact on computational efficiency and on handling complex geological settings. For instance, it is shown that the minimization problem provides the means to manage under-sampled fold structures and thickness variations in the layers. Other applications are also presented such as salt envelope surface modeling and mechanical restoration.

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