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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

Otimização de estruturas com fluido contido sujeita a múltiplos carregamentos. / Optimization of contained fluid structures subjected to multiple load cases.

Miracca, Fábio Brescia 26 March 2007 (has links)
Muitas vezes encontram-se na Engenharia, estruturas que contenham fluido em seu interior, (estruturas com fluido contido). Uma vez que para determinados casos de carregamento, como por exemplo, carregamento hidrostático, o fluido colabora com a rigidez, pode ser conveniente para o engenheiro considerar a presença deste fluido com o objetivo de se obter uma estrutura mais leve, principalmente nos casos onde a presença do fluido é obrigatória à operação da estrutura. Nesta dissertação, uma metodologia para otimização de estruturas com fluido contido é apresentada. Tal metodologia engloba a otimização de uma estrutura real, utilizando otimização paramétrica (OP) e topológica (OT). A rotina de OT implementada permite projetar estruturas compostas de aço e fluido contido (FC), e considera múltiplos casos de carregamento, peso próprio e a possibilidade de escolha de regiões a serem otimizadas ou não. Para validação da rotina de OT, exemplos clássicos da literatura considerando a presença de um ou dois materiais são apresentados. Para implementar o algoritmo para resolução da OT utiliza-se um programa comercial para a análise de elementos finitos, complementado com uma rotina externa elaborada em linguagem do próprio programa. Isto possibilita agregar a vantagem da utilização de um programa comercial, multidisciplinar, e com um grande número de elementos finitos implementados, com a versatilidade de uma linguagem de programação, permitindo implementar uma solução específica para o problema estudado. Como exemplo, apresenta-se um estudo de caso real, voltado a estruturas navais, apresentando, além da análise da estrutura inicial estudada, uma otimização paramétrica, e uma otimização topológica tridimensional da estrutura. Os resultados alcançados, mostram-se satisfatórios, uma vez que a estrutura obtida no estudo de caso específico apresenta uma redução significativa em seu peso atendendo aos requisitos de projeto. / Several times, it is found in Engineering, structures with fluid inside (contained fluid structures). Since for some load cases, for instance, hydrostatic load, the fluid collaborates with stiffness, it may be convenient for the engineer to take into account this fluid to make the structure lighter, mainly if the presence of fluid is mandatory for operation. In this work, a methodology for contained fluid structures optimization is presented. This methodology includes parametric and topology optimizations of a real structure. Topology optimization routine implemented allows us to design structures made by steel and contained fluid, and includes several load cases, self-weight, and the possibility of choosing areas to optimize or not. To validate the topology optimization routine, classical examples with one or two material are showed. To perform topology optimization procedure, Finite Element Analysis commercial software is applied together with an external routine implemented using the software programming language, this allows us to take advantage of a multidisciplinary commercial software, which has a large number of finite elements implemented, and the versatility of a customized program for the studied problem. As an example, it is showed a real case, within naval structures describing the initial structure analysis and its parametric optimization, and a tridimensional topology optimization. The results obtained are satisfactory, since the final structure obtained has a significant reduction in its weight.
12

Otimização de estruturas com fluido contido sujeita a múltiplos carregamentos. / Optimization of contained fluid structures subjected to multiple load cases.

Fábio Brescia Miracca 26 March 2007 (has links)
Muitas vezes encontram-se na Engenharia, estruturas que contenham fluido em seu interior, (estruturas com fluido contido). Uma vez que para determinados casos de carregamento, como por exemplo, carregamento hidrostático, o fluido colabora com a rigidez, pode ser conveniente para o engenheiro considerar a presença deste fluido com o objetivo de se obter uma estrutura mais leve, principalmente nos casos onde a presença do fluido é obrigatória à operação da estrutura. Nesta dissertação, uma metodologia para otimização de estruturas com fluido contido é apresentada. Tal metodologia engloba a otimização de uma estrutura real, utilizando otimização paramétrica (OP) e topológica (OT). A rotina de OT implementada permite projetar estruturas compostas de aço e fluido contido (FC), e considera múltiplos casos de carregamento, peso próprio e a possibilidade de escolha de regiões a serem otimizadas ou não. Para validação da rotina de OT, exemplos clássicos da literatura considerando a presença de um ou dois materiais são apresentados. Para implementar o algoritmo para resolução da OT utiliza-se um programa comercial para a análise de elementos finitos, complementado com uma rotina externa elaborada em linguagem do próprio programa. Isto possibilita agregar a vantagem da utilização de um programa comercial, multidisciplinar, e com um grande número de elementos finitos implementados, com a versatilidade de uma linguagem de programação, permitindo implementar uma solução específica para o problema estudado. Como exemplo, apresenta-se um estudo de caso real, voltado a estruturas navais, apresentando, além da análise da estrutura inicial estudada, uma otimização paramétrica, e uma otimização topológica tridimensional da estrutura. Os resultados alcançados, mostram-se satisfatórios, uma vez que a estrutura obtida no estudo de caso específico apresenta uma redução significativa em seu peso atendendo aos requisitos de projeto. / Several times, it is found in Engineering, structures with fluid inside (contained fluid structures). Since for some load cases, for instance, hydrostatic load, the fluid collaborates with stiffness, it may be convenient for the engineer to take into account this fluid to make the structure lighter, mainly if the presence of fluid is mandatory for operation. In this work, a methodology for contained fluid structures optimization is presented. This methodology includes parametric and topology optimizations of a real structure. Topology optimization routine implemented allows us to design structures made by steel and contained fluid, and includes several load cases, self-weight, and the possibility of choosing areas to optimize or not. To validate the topology optimization routine, classical examples with one or two material are showed. To perform topology optimization procedure, Finite Element Analysis commercial software is applied together with an external routine implemented using the software programming language, this allows us to take advantage of a multidisciplinary commercial software, which has a large number of finite elements implemented, and the versatility of a customized program for the studied problem. As an example, it is showed a real case, within naval structures describing the initial structure analysis and its parametric optimization, and a tridimensional topology optimization. The results obtained are satisfactory, since the final structure obtained has a significant reduction in its weight.
13

Amplificateur de puissance autonome pour applications OFDM et beamforming de la 5G aux fréquences millimétriques en technologie CMOS avancée / Self-contained Power Amplifier for OFDM and Beamforming 5G Applications at Millimeter-wave Frequencies in Advanced CMOS Technology

Moret, Boris 05 October 2017 (has links)
Afin de répondre à la demande croissante du nombre d'objets connectés et de débits de données plus élevés, la cinquième génération de réseau mobile (5G) va être déployée.Pour répondre à ces défis, la 5G utilisera le beamforming pour améliorer la qualité de transmission et étendre la couverture du réseau. En raison du manque de spectre RF disponible en dessous de 6 GHz, l'industrie de la téléphonie mobile étudie actuellement les bandes de fréquences millimétriques en particulier autour de 28 GHz. L'utilisation de la technologie CMOS pour les applications 5G apparait prometteuse pour le marché de masse que vise la 5G, d'autant qu'aujourd'hui la miniaturisation des transistors CMOS permet un fonctionnement compétitif aux fréquences millimétriques. Pour répondre à toutes les attentes de la 5G notamment en termes de fiabilité, de nouvelles idées en rupture, avec le self-healing et le self-contained, permettent d’utiliser au maximum les avantages de la technologie CMOS tout en proposant un fonctionnement fiable pou rl’amplificateur. Dans le cadre du self-healing et du self-contained, plusieurs circuits son tintégrés sur silicium tel qu'un amplificateur intégrant un détecteur de puissance totalement non invasif pour le self-healing et un amplificateur équilibré pour le selfcontained. / In order to meet the growing demand for more connected objects and higher data rates,the fifth generation of mobile network (5G) will be deployed. To address thesechallenges, the 5G will use beamforming to improve the transmission quality and extendthe network coverage. Due to the lack of available RF spectrum below 6 GHz, the mobileindustry is studying millimeter wave frequency bands in particular around 28 GHz. Theuse of CMOS technology for 5G applications is promising for the 5G mass market,especially nowadays the miniaturization of CMOS transistors allows competitiveoperation at millimeter frequencies. To meet all the expectations of the 5G especially interms of reliability, new breakthrough ideas, with the self-healing and the selfcontained,allow to use all the benefits of CMOS technology to the maximum whileoffering reliable operation for the amplifier. Within the framework of self-healing andself-contained, several circuits are integrated on silicon such as an amplifier integratedwith a totally non-invasive power detector for self-healing and a balanced self-containedamplifier.
14

Ayurvedic and Bionian Theories of Thinking: Mental Digestion and the Truth Instinct

Labbe-Watson, Jenna G. 18 August 2020 (has links)
No description available.
15

A System Approach to Fission-Fusion Symbiosis

Gordon, Charles William 04 1900 (has links)
<p> Three symbiotic systems are considered. These include the possibility of coupling the tritium production in a fission reactor with the fertile conversion in a fusion blanket. Equations for the fuel dynamics, power output, efficiency and costs of a symbiotic, selfcontained power station are developed and evaluated for a specific, 1500 MWe fission reactor operating on a thorium cycle and some fusion parameters. It is concluded that a system using the tritium produced in a fission reactor has lower costs and increased power output when compared to an alternate system. </p> / Thesis / Master of Engineering (MEngr)
16

Contained-Electrospray Ionization: A Multi-Modal Ionization Platform for the Facile On-Line Modification of Biological Molecules for Rapid Detection via Mass Spectrometry

Burris, Benjamin James 15 September 2022 (has links)
No description available.
17

Flottation réactive à l'ozone de contaminants modèles issus de papiers récupérés : étude hydrodynamique et réactivité / Ozone reactive flotation of model contaminants contained in recovered papers : hydrodynamics and reactivity study

Herisson, Alexandre 25 June 2018 (has links)
La diminution de la qualité des collectes des papiers récupérés ainsi que l’accumulation de substances dissoutes dans les eaux de procédés affecte l’efficacité des lignes de désencrage industrielles et contamine davantage les effluents liquides. Dans ce contexte, le LGP2 a développé depuis quelques années un procédé innovant de désencrage, la flottation réactive à l’ozone, afin de dégrader chimiquement les polluants dissouts en parallèle de l’élimination de l’encre. Afin de mieux comprendre les mécanismes mis en jeu, des essais de flottation à l’air et à un mélange ozone/oxygène, sur trois contaminants modèles, sélectionnés après une étude bibliographique préalable, ont été réalisés dans un milieu diphasique gaz/liquide, en l’absence de fibres cellulosiques. Les expérimentations ont été conduites sur deux pilotes de laboratoire instrumentés : une colonne à bulles fonctionnant avec de l’air uniquement, pour l’étude du comportement hydrodynamique (taille et distribution de bulles, rétention gazeuse) en présence des contaminants dissouts, et une deuxième colonne à bulles, similaire mais conçue avec des matériaux résistants aux gaz corrosifs, dédiée à l’étude des réactions d’oxydation en présence d’ozone. L’examen du comportement hydrodynamique montre que les conditions de débit de gaz et d’injection retenues conduisent à des tailles de bulles optimales pour une flottation efficace, que ce soit en présence ou absence de contaminants. Ces conditions obtenues avec de l’air ont été transposées en première approximation au système ozone/oxygène. L’étude du transfert de l’ozone et de sa réactivité avec les trois contaminants modèles, à différentes températures et concentrations en ozone, a conduit à la détermination des constantes cinétiques de réaction et a montré que les contaminants étaient, selon leur nature, oxydés ou dépolymérisés. Bien que la DCO des solutions traitées diminue très peu après la flottation réactive à l’ozone, la qualité des effluents est améliorée sur le plan de leur biodégradabilité. / The decrease of the recovered paper collection quality and the accumulation of dissolved substances in process water affect the deinking line efficiency and contaminate more and more the liquid effluents. In this context the LGP2 has developed an innovative deinking process, the ozone reactive flotation, to chemically degrade dissolved pollutants in parallel with ink removal. To better understand the mechanisms involved, air and ozone/oxygen flotation trials have been conducted on three model contaminants selected in a preliminary bibliographic review, in a two-phase gas/liquid system, in the absence of fibers. Experiments have been carried out on two instrumented laboratory pilots: a bubble column operating only with air for the study of the hydrodynamics of the reactor (bubbles size and distribution, gas hold-up) in the presence of dissolved contaminants, and a second one, similar in its conception but built using materials resistant to corrosive gas, dedicated to the study of the oxidation reactions with ozone. The evaluation of the hydrodynamics related to gas flow and injection system selected, studied with air but supposed to be the same with ozone/oxygen gas mixture, shows that the bubble size, with or without contaminants, is optimal for an efficient flotation process. The study of ozone mass transfer and reactivity with the three model contaminants, for several temperatures and ozone concentrations, leads to the calculation of kinetic constants and shows that the contaminants, depending on their nature, have been oxidized or depolymerized. Although the COD of the treated solutions does not decrease a lot after the ozone reactive flotation, the effluent quality has been improved in terms of biodegradability since contaminants are partially degraded.
18

Logistické zabezpečení zásahu při výskytu slintavky a kulhavky ve velkochovu s 300 kusy skotu / Logistics, security and intervention, a strategic approach to the occurrence of foot-and-mouth disease on 300 livestock in a farming community

ŘEZNÍČKOVÁ, Martina January 2008 (has links)
The foot and mouth disease is an acute, very contagious virus disease of even-toed ungulates (cattle, Wheel, pigs). The primary source of the infection is an ill animal, a secondary source are all the subject contaminated by the originator of the illness. Also people often pass the illness (on their shoes and also clothes). At present, the foot and mouth disease in Great Britain is mentioned at most; however, the epi-centers of the contagion of this illness may be found in many other places all around the world. Although the last occurrence of the foot and mouth disease was recorded in 1975 in the Czech Republic, the real risk of spreading this infection in our territory exists also at present. The people get infected with foot and mouth disease may very seldom. Also the most animals are able to survive this disease; in spite of this fact, spreading the infection in the breeding causes immense economic loss. For this reason, many countries consider necessary to fight against the infection by all the possible means. First of all the prevention and preparation of various plans and preparation of experts is accentuated. In case of any suspicion concerning the foot and mouth disease it is necessary to take the necessary measures. Only thanks to a thorough preparation and correct observation of all the measures it is possible to fight effectively with this dangerous infection, although at the expense of lives of many animals.
19

Multi-objective control of a self-locking compact electro-hydraulic cylinder drive

Grønkær, Nikolaj, Nielsen, Lasse Nørby, Nielsen, Frederik Ødum, Ketelsen, Søren, Schmidt, Lasse 25 June 2020 (has links)
The field of self-contained linear hydraulic drives based on variable-speed electrical motors and fixed displacement pumps is gaining interest from both industry and academia. Some of the main reasons for this is the possibility to improve the energy efficiency of such drives compared to conventional valve controlled drives, and the possibility for electrical regeneration allowing power sharing between multiple drives [1]. The main drawback for such types of drive concepts is a low pressure in the nonload carrying cylinder chamber. This induces a low drive stiffness limiting the achievable drive bandwidth and hence the application range. However, a so-called self-locking compact drive architecture recently proposed allows maintaining a proper drive stiffness by virtue of separate forward and return flow paths, combining the advantages of efficient flow control into the cylinder and a throttle driven flow out of the cylinder. The multiple inputs available in this architecture allow the control to target several objectives concurrently, for example piston motion, drive stiffness and fluid temperature. The purpose of the study presented is to analyse the dynamic couplings between the control objectives via relative gain array (RGA) methods, and the realization of input- and output transformations effectively decoupling relevant dynamic interactions. These transformations allow the usage of simple SISO-controllers for each control objective, and a method for controlling motion and fluid temperature concurrently, is proposed and experimentally verified.
20

Bootstrap reservoir concepts for electro-hydraulic compact cylinder drives

Ketelsen, Søren, Kolks, Giacomo, Andersen, Torben Ole, Schmidt, Lasse, Weber, Jürgen 26 June 2020 (has links)
This paper presents a conceptual study aiming to improve the compactness of electro-hydraulic compact drives (ECD ). In most current ECD architectures, gas accumulators are used as volume compensators for the flow imbalance emerging whenever asymmetric single rod cylinders are used. To stay within a required reservoir pressure range typically from two to four bar, a large gas volume is required, compromising system compactness. Combining conventional ECD architectures with a bootstrap reservoir offers a greater degree of freedom in system design, which enables downsizing or avoidance of the gas volume. Another potential benefit by including a bootstrap reservoir is the possibility of elevating the backpressure of the ECD thus enhancing drive stiffness, expanding the application range and market acceptance. Based on an open analysis of the solution space occurring when introducing a bootstrap reservoir, three system architectures are selected for a conceptual study. The results show that the downsizing potential is strongly dependent on the maximum friction force and the area ratio of the bootstrap reservoir pistons, while a linear analysis reveals that for some system architectures the bootstrap reservoir may severely influence the system dynamics. Simulation results confirm the functionality of the proposed system architectures, and show that a potential for downsizing/avoiding the gas volume, as well as increasing the ECD stiffness is present.

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