Global ETD Search

61	Quadruped robot control and variable leg transmissions Ingvast, Johan January 2006 (has links) The research presented in this thesis regards walking of quadruped robots, and particularly the walking of the Warp1 robot. The motivation for the robot is to provide a platform for autonomous walking in rough terrain. The thesis contains six papers ranging from development tools to actuation of robot legs. The first paper describes the methods and tools made for control development. These tools feature: programming of the robot without low level coding (C-code); that the controller has to be built only once for simulation and experiments; and that names of variables and constants are unchanged through the chain of software Maple -- Matlab -- Simulink -- Real~Time~Workshop -- xPC--Target. Three controllers, each making the robot walk are presented. The first controller makes the robot walk using the crawl gait. The method uses static stability as method for keeping balance and the instantaneous trunk motions are given by a concept using the so called weight ratios. A method for planning new footholds based on the positions of the existing footholds is also proposed and the controller experimentally verified. The second walking controller shows that the robot also can walk dynamically using the trot gait. The method proposed uses information from ground contact sensors on the feet as input to control balance, instead of, which is common, inertial sensors. It is experimentally verified that Warp1 can trot from level ground onto a slope and turn around while staying balanced. The main ideas of these two walking controllers are fused in the third which enables smooth transitions between crawl and trot. The idea of using the ground contact sensors from the first controller is here used to estimate the position of the center of mass. This controller uses weight ratios in the gait crawl as well as in the dynamic gait trot. Hence, the method of using weight ratios is not only useful for static stability for which it was originally intended. The controller is experimentally verified on Warp1. The Warp1 robot weighs about 60 kg, has 0.6 m long legs with three actuated joints on each. The speed and strength is sufficient only for slow walking, even though the installed power indicates that it should be enough for faster walking. The reason is that a walking robot often needs to be strong but slow when the feet are on the ground and the opposite when in the air. This can not be achieved with the motors and transmissions currently used. A transmission called the passively variable transmission (PVT) is proposed which enhance motor capabilities of robot joints. It is elastic, nonlinear and conservative. Some general properties for elastic transmissions are derived such that they can be compared with conventional transmissions. The PVT gives strong actuation at large loads and fast actuation at small loads. The proposed transmission is compared to a conventional transmission for a specific task, and the result is that a smaller motor can be used. / QC 20100831 walking robot quadruped walking crawl trot passively variable transmission PVT variable transmission continuously variable transmission velocity ratio torque ratio Other engineering mechanics Övrig teknisk mekanik
62	Contribution à l'étude de la croissance par transport en phase gazeuse des semi-conducteurs Pb0,8Sn0,2Te et GaAs dans un environnement de gravité réduite : expérience MF095 EURECA-1 : aspects thermodynamique et hydrodynamique Bouchet, Stéphanie 30 April 1993 (has links) (PDF) Avec pour objectifs la modélisation des mécanismes de croissance par transport en phase gazeuse et l'influence du vecteur gravité sur l'anisotropie et la cinétique de croissance, des expériences ont été préparées et réalisées sur terre, en microgravité et en hypergravité. Les matériaux choisis sont le ternaire Pb0,8Sn0,2Te par transport physique et le binaire GaAS sur des demi-billes orientées de GaAs par transport chimique.<br />Une étude thermodynamique des différentes pressions partielles des éléments présents dans la phase gazeuse a été réalisée. La diffraction de Läue en retour et la microscopie électronique nous ont permis d'identifier les facettes de GaAs et leurs épaisseurs. Par spectroscopie RAMAN, nous avons mis en évidence des gradients de concentration en fonction de g du dopant Sn dans les couches déposées de GaAs.<br />Une modélisation numérique des écoulements basée sur une méthode spectrale de tye Tau - Chebyshev a été effectuée. Système ternaire PVT CVT Thermodynamique Transfert de masse par diffusion Diffraction Läue en retour Spectroscopie Raman Hypergravité Régimes de Coriolis et centrifuge
63	Integration of Photovoltaic Thermal Technology in the Greenhouses (A case study of Greece and Portugal) Shah, Syed Aman January 2022 (has links) The thesis work was done as a part of the company's proposal writing work for the Horizon Europe projects, which is the European Union's key funding program for research and innovation with a budget of €95.5 billion. The budget for this project call was €5 million and aimed towards demonstrating the possibilities of Photovoltaic thermal technologies (PVT), which will produce heat and electricity at the same time on agricultural land to combat climate change. The initial stage of the project, which the thesis work corresponds to, consists of the concept of implementing the objectives of the call and demonstrating how it could be achieved by forming a consortium of different companies, allocating the sites, possible applications of the PVT technology, understanding the plants which can grow in the relevant climate conditions under the shading of the panels. There are different companies who participate in the project call and, if they succeed, are liable to demonstrate the objectives of the call under the allocated budget and share the results with the European Union. The thesis work tried to focus on the company's objective for the call, which was to find out the suitable crops to be planted under the integrated PVT greenhouses, details on the weather conditions and applications of heat and electricity on the demonstration sites, i.e., Greece and Portugal. The emphasis was also given to creating a business canvas model and doing the strengths, weaknesses, opportunities, and threats (SWOT) analysis to make a business plan for this project. In this project, an Absolicon X10 PVT collector has been proposed with thermal heat up to 75 ºC and electricity at 230V. The outcomes also showed that each PVT collector integrated into the greenhouse could produce 4.73 MWh/year of thermal energy and can supply 2.2 MWh/year of electrical energy, which can save up to 0.48 tons/year of oil equivalent and avoid 37.6 tons of CO2 emissions during its lifetime of 25 years compared to burning oil. Considering the weather conditions in Greece and Portugal and to make sure the plants do not need much shading, tomatoes, barley and cacao seeds were identified as the potential crops to be planted in the PVT-integrated greenhouses. Renewable energy photovoltaic photovoltaic thermal solar thermal PV PVT crops plantation under greenhouses greenhouses climate change and arable lands. Annan elektroteknik och elektronik
64	Novel Application of Combined Heat and Power for Multi-Family Residences and Small Remote Communities Alqaed, Saeed A. 24 May 2017 (has links) No description available. Mechanical Engineering
65	The Effects of Caffeine Gum Administration on Reaction Time and Lower Body Pain During Cycling to Exhaustion Jankowski-Wilkinson, Andrea Faye 02 September 2008 (has links) No description available. Behaviorial Sciences Biomedical Research Health Health Care Pharmacology Physical Education Sports Medicine caffeine reaction time lower body pain caffeine gum stay alert gum cycling to exhaustion psychomotor vigilance test PVT
66	Thermo-Economic Study of Hybrid Photovoltaic-Thermal (PVT) Solar Collectors Combined with Borehole Thermal Energy Storage Systems Aldubyan, Mohammad Hasan 24 May 2017 (has links) No description available. Mechanical Engineering Engineering Energy Photovoltaic Thermal PVT PV thermal collector Geothermal Ground loop GCHP GHX BTES solar energy renewable energy building cell temperature cell efficiency thermo economic borehole storage TRNSYS simulation
67	The impact of voltage scaling over delay elements with focus on post-silicon tests Heck, Guilherme 09 March 2018 (has links) Submitted by PPG Ci?ncia da Computa??o (ppgcc@pucrs.br) on 2018-08-22T17:30:17Z No. of bitstreams: 1 GUILHERME HECK_TES.pdf: 7520580 bytes, checksum: 0abf48b5a455b7c50fa0b30109a1ee57 (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-08-23T12:09:32Z (GMT) No. of bitstreams: 1 GUILHERME HECK_TES.pdf: 7520580 bytes, checksum: 0abf48b5a455b7c50fa0b30109a1ee57 (MD5) / Made available in DSpace on 2018-08-23T13:31:43Z (GMT). No. of bitstreams: 1 GUILHERME HECK_TES.pdf: 7520580 bytes, checksum: 0abf48b5a455b7c50fa0b30109a1ee57 (MD5) Previous issue date: 2018-03-09 / A demanda sem precedentes por poderosos dispositivos de processamento gerou quebras consecutivas de paradigma de projeto de circuito na ?rea de Circuitos Integrados (CIs). O uso de tecnologia submicrom?trica profunda aumenta a densidade de integra??o a n?veis nunca vistos antes. No entanto, com CIs mais densos, a inclina??o do rel?gio e outros efeitos requerem compensa??es em design s?ncrono, o que pode aumentar a ?rea e o consumo de energia a valores inaceit?veis. Como alternativa, o paradigma ass?ncrono est? re-emergindo, focado na efici?ncia de energia. Entre os modelos cl?ssicos de projeto ass?ncrono, o Empacotamento-de-Dados (ED) se destaca pela sua capacidade de fornecer alto desempenho, reduzir a pot?ncia e obter resultados de ?rea semelhante ? dos modelos s?ncronos. Diferentemente dos modelos mais robustos de quase-atraso insens?vel, uma outra classe comum de modelos para implementar circuitos ass?ncronos, circuitos ED requerem o uso extensivo de Elementos de Atraso (EAs) para garantir a correta funcionalidade. No entanto, todos os circuitos s?o afetados por varia??es de Processo, Tens?o e Temperatura (PTT), incluindo a L?gica Combinacional (LC) em ED impondo margem em elementos de atraso. Al?m disso, projetos atuais usam escalonamento de tens?o para melhorar a efici?ncia de energia, o que afeta o atraso diferentemente em LCs e EAs adicionando mais margem em EAs. Um novo modelo baseado em ED chamado Blade usa o conceito de resili?ncia como uma esperan?a para evitar a margem de atraso causada por PTT e escalonamento de tens?o. Contudo, o uso de dois elementos de atraso ir? representar mais margens e mais tempo de teste no circuito final. Assim, este trabalho mostra uma an?lise do comportamento de elementos de atraso sob escalonamento de tens?o e o impacto em testes p?s-sil?cio. Ele introduz um novo termo para determinar o impacto da escala de tens?o sobre os elementos de atraso e tamb?m a compara??o entre os EAs mais utilizados em projetos ED usando esta nova m?trica. Uma an?lise de testes em modelos ED e Blade ? apresentada e o impacto da escala de tens?o nestes projetos ? analisado. Finalmente, um novo elemento de atraso ? proposto focando na redu??o de margem e redu??o no tempo de teste para o modelo Blade. / The unprecedented demand for powerful processing devices has generated consecutive circuit design paradigm breaks in the Integrated Circuits (ICs) arena. The use of deep submicron technology increases the integration density to levels never seen before. However, with denser ICs, clock skew and other effects require compensations in synchronous design, which can increase area overhead and power consumption to unacceptable values. As an alternative, the asynchronous paradigm is re-emerging, focused on power efficiency. Among classical asynchronous design templates, the Bundled-Data (BD) one stands off for its capability to provide high performance, reduce power and achieve area results similar to that of synchronous designs. Unlike the more robust Quasi-Delay Insensitive (QDI) templates, another common class of templates to implement asynchronous circuits, BD circuits require the extensive use of Delay Elements (DEs) to guarantee correct functionality. However, all circuits are affected by Process, Voltage and Temperature (PVT) variations, including the Combinational Logic (CL) on BD imposing margin on delay elements. In addition, current designs use voltage scaling to improve power efficiency, which impacts the delay differently in CLs and DEs adding more margin in DEs. A new template based on BD called Blade uses resiliency concept as a hope to avoid the delay margin caused by PVT and voltage scaling. Although, the use of two delay elements will represents more margins and extra test time on final circuit. So, this work shows an analysis of delay elements behavior under voltage scaling and the impact on post-silicon tests. It introduces a new term to determine the voltage scaling impact on delay elements and also the comparison between the most used DEs on BD designs using this novel metric. An analysis of tests in BD and Blade templates are presented and the impact of voltage scaling in these designs is analyzed. Finally, a novel delay element is proposed focusing in margin reduction and reduction in test time for Blade template. Delay Elements Voltage Scaling Asynchronous Bundled-Data Resiliency Blade Process Post-Silicon Tests Voltage and Temperature (PVT) Variations Elementos de Atraso Escalonamento de Tens?o Ass?ncronos Empacotamento de Dados Resili?ncia Varia??o de Processo Tens?o de Temperatura Teste P?s-Sil?cio
68	Analysis of a novel thermoelectric generator in the built environment Lozano, Adolfo 05 October 2011 (has links) This study centered on a novel thermoelectric generator (TEG) integrated into the built environment. Designed by Watts Thermoelectric LLC, the TEG is essentially a novel assembly of thermoelectric modules whose required temperature differential is supplied by hot and cold streams of water flowing through the TEG. Per its recommended operating conditions, the TEG nominally generates 83 Watts of electrical power. In its default configuration in the built environment, solar-thermal energy serves as the TEG’s hot stream source and geothermal energy serves as its cold stream source. Two systems-level, thermodynamic analyses were performed, which were based on the TEG’s upcoming characterization testing, scheduled to occur later in 2011 in Detroit, Michigan. The first analysis considered the TEG coupled with a solar collector system. A numerical model of the coupled system was constructed in order to estimate the system’s annual energetic performance. It was determined numerically that over the course of a sample year, the solar collector system could deliver 39.73 megawatt-hours (MWh) of thermal energy to the TEG. The TEG converted that thermal energy into a net of 266.5 kilowatt-hours of electricity in that year. The second analysis focused on the TEG itself during operation with the purpose of providing a preliminary thermodynamic characterization of the TEG. Using experimental data, this analysis found the TEG’s operating efficiency to be 1.72%. Next, the annual emissions that would be avoided by implementing the zero-emission TEG were considered. The emission factor of Michigan’s electric grid, RFCM, was calculated to be 0.830 tons of carbon dioxide-equivalent (CO2e) per MWh, and with the TEG’s annual energy output, it was concluded that 0.221 tons CO2e would be avoided each year with the TEG. It is important to note that the TEG can be linearly scaled up by including additional modules. Thus, these benefits can be multiplied through the incorporation of more TEG units. Finally, the levelized cost of electricity (LCOE) of the TEG integrated into the built environment with the solar-thermal hot source and passive ground-based cold source was considered. The LCOE of the system was estimated to be approximately $8,404/MWh, which is substantially greater than current generation technologies. Note that this calculation was based on one particular configuration with a particular and narrow set of assumptions, and is not intended to be a general conclusion about TEG systems overall. It was concluded that while solar-thermal energy systems can sustain the TEG, they are capital-intensive and therefore not economically suitable for the TEG given the assumptions of this analysis. In the end, because of the large costs associated with the solar-thermal system, waste heat recovery is proposed as a potentially more cost-effective provider of the TEG’s hot stream source. / text Thermoelectric generator TEG Novel thermoelectric generator Thermoelectrics Thermoelectric effect Thermoelectric modules Thermoelectric device Patent application Hot stream source Cold stream source EIA EERE Systems-level analysis Energy balance Control volume analysis Thermodynamic analysis Insolation data Insolation incident on a panel Incident insolation Extraterrestrial insolation NREL Ambient temperature data NOAA Renewable energy sources Energy generation technology Electricity generation technology Thermal energy Coupled system Emissions Greenhouse gas GHG Emissions analysis Zero-emission Emissions avoided Emission factor EF Reliability First Corporation RFC Built environment Integrated into the built environment Solar-thermal energy Solar collector system Photovoltaic thermal PVT panel Thermal storage tank Geothermal energy Geothermal heat pump GHP Ground source heat pump GSHP Numerical analysis Numerical model MATLAB Finite-difference Euler explicit Electric grid Annual energetic performance Annual electricity generation Operating efficiency System efficiency Thermodynamic characterization Economic analysis Levelized cost of energy LCOE Waste heat recovery Carbon dioxide equivalent CO2e Capital costs Installed costs Operating and maintenance costs

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