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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.
81

Análise estrutural de reservatórios enterrados de argamassa armada com telas de aço soldadas / Structural analysis of swimming pools and water tanks in ferrocement with welded mesh

Dálim Gomes Paniago 25 June 1998 (has links)
A argamassa armada passou a ser utilizada na construção de reservatórios de água e piscinas no início da década de 60. Apesar do sucesso de várias aplicações, até hoje a tecnologia tem se fundamentado em bases empíricas, sem o estabelecimento de metodologias que permitam a elaboração de projetos, melhorias no método de construção e uma melhor avaliação dos riscos e da confiabilidade do sistema construtivo. O presente trabalho pretende contribuir para aumentar o conhecimento acerca do comportamento estrutural da membrana de argamassa armada em piscinas e reservatórios. Foram realizadas simulações numéricas por computador com o intuito de se investigar o comportamento da membrana quando submetidas à ação da água, de recalques e de variações de temperatura. A influência das dimensões da estrutura e da resistência da argamassa também foram analisadas. São discutidos estes e outros aspectos relacionados à fase de projeto. O trabalho apresenta ainda comentários sobre cada etapa de construção, bem como alguns cuidados necessários para a garantia de um material de boa qualidade. Tendo em vista a obtenção de uma estrutura durável e com bom desempenho, é preciso que cada equipe de trabalho tenha um palavra de ordem: aos projetistas, detalhamento; aos construtores, controle; à mão-de-obra, conscientização. / Ferrocement application in water tanks and swimming pools have started at the early 60\'s. Even though various applications had been succeed, until nowadays the techonology is essentially based on practical experience. There are no established methodologies which permit rational design, construction method improvement and a better assessment of the risks and reliability of the construction system. This work intend to contribute to the knowledge about the structural behavior of the ferrocement folded plate swimming pools and water tanks. Computer numerical simulations were made to investigate the membrane behavior under water loading, settlement and temperature variations. The influence of structure dimensions and mortar strength were also studied. These and others aspects related with the design method are discussed. The thesis also presents some comments about each construction stage as well as some cares needed to guarantee a good quality material. Looking for a durable and good performance structure, the order word to the designer is detailing, to the constructor is control and to the staff is awareness.
82

Análise do ciclo de esterilização de tanques assépticos em procesamento de alimentos / Evaluation of sterilization cycle of aseptic tank applied in food processing

Scucuglia, Márcio, 1974- 26 August 2018 (has links)
Orientador: Flavio Luis Schmdit / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-26T04:59:10Z (GMT). No. of bitstreams: 1 Scucuglia_Marcio_M.pdf: 2766345 bytes, checksum: df718c4c465f3ea8e35d990cbd5ffbc6 (MD5) Previous issue date: 2014 / Resumo: Tanques assépticos são equipamentos aplicados em linhas de processamento de produtos longa-vida, com o objetivo de estocar o produto previamente esterilizado até o envase asséptico, mantendo a condição de esterilidade comercial obtida nas etapas anteriores. Para evitar a recontaminação do produto, o equipamento deve ser levado a condição de esterilidade, sendo aplicado um procedimento de aquecimento, desaeração e esterilização. Por ser uma etapa crítica, o ciclo de esterilização é validado por protocolos específicos que visam garantir a integridade da operação. A demanda de equipamentos com capacidades cada vez maiores e as implicações desse aumento na eficiência da esterilização tornaram importante uma análise mais detalhada dos resultados obtidos nos protocolos atuais. Este trabalho teve por objetivo avaliar os ciclos de esterilização de um tanque asséptico, baseado na distribuição de temperatura e pressão em seu interior, e a partir dos resultados, aumentar a compreensão dos fenômenos envolvidos na esterilização e quantificar sua eficiência. A análise das variáveis revelou que o ciclo de desaeração do tanque asséptico não foi completa, com retenção de ar representando de 13 a 23% do volume total do equipamento. Como consequência o processo de esterilização ocorreu em condição de não saturação de vapor. Esta situação altera o mecanismo de destruição térmica de microrganismos da condição úmida para não-úmida, na qual a resistência térmica dos esporos é mais elevada, levantando a questão da real eficiência dos processos e protocolos de esterilização atuais. .A aparente garantia da esterilidade comercial dos processos atuais pode ser explicada pelo uso de temperaturas e tempos excessivos. A revisão de procedimentos, protocolos e critérios de sucesso dos projetos existentes pode resultar em maior segurança quanto à eficiência de esterilização e redução de custos. Um novo protocolo de validação é proposto em refletindo os novos critérios de sucesso estabelecidos neste trabalho / Abstract: Aseptic tank systems are applied to production lines for shelf-stable, long-life products in order to store sterile product until aseptic filling, maintaining the commercial sterility condition achieved from previous production steps. To avoid microbial recontamination of the product, a sterility condition must be achieved in the aseptic tank system through the application of a heating, venting, and sterilization cycle. This cycle must be submitted to specific validation protocols to ensure operational integrity. The demand for larger capacity systems and the implication of this volume increase on sterilization efficiency require a more detailed review of the results obtained from current validation protocols. The purpose of this work was to evaluate an aseptic tank¿s sterilization cycles, through study of temperature distribution and internal pressure, in order to better understand key phenomena in aseptic tank sterilization and to quantify its efficiency. The analysis showed that the venting cycle was insufficient, with remaining air on the order of 13%-23% of the total tank volume. Consequently, the subsequent sterilization process was not conducted at the saturation point for steam. This different condition changes the kinetics for thermal destruction of microorganisms from a wet state to a dry state in which thermal resistance of spores is higher. This finding raises a question regarding the true efficacy of the sterilization process and validation protocols currently applied. The apparent success of current sterilization processes could be explained by the usage of excessive temperature and time. The review of procedures, protocols, and success criteria of current projects could result in greater assurance of sterilization efficacy and in cost reduction. A new validation protocol is proposed to reflect the new success criteria developed in this work / Mestrado / Tecnologia de Alimentos / Mestre em Tecnologia de Alimentos
83

Determinação experimental da curva do sistema e da potência consumida em unidade de bombeamento alimentando dois tanques em desnível com fluidos diferentes / Experimental determination of the curve of the system and power consumed in pumping unit feeding two tanks in different fluids with gap

Pereira, Flavio Nelson 12 December 2011 (has links)
Orientador: Elias Basile Tambourgi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T18:15:28Z (GMT). No. of bitstreams: 1 Pereira_FlavioNelson_M.pdf: 3206674 bytes, checksum: 13d3a08e501d1a7a3efe94db596a1123 (MD5) Previous issue date: 2011 / Resumo: A bomba centrífuga é uma máquina dinâmica que só pode trabalhar nos pontos de sua curva. Consequentemente, a soma das resistências da tubulação e seus componentes durante a operação deve se situar exatamente na sua curva ou curva da bomba. A literatura para a seleção e especificação deste equipamento alimentando apenas um ponto como um tanque ou vaso é vasta, porém, são raros os trabalhos no que concerne a alimentação simultânea de dois ou mais tanques em cotas diferentes, que mostrem o comportamento da pressão ao longo do processo e a curva desse sistema. Esta alimentação simultânea é dita ramificada. O presente trabalho teve por objetivo projetar e montar uma unidade experimental em escala piloto para determinar a curva do sistema e a potência consumida de uma bomba centrífuga quando esta alimenta dois tanques em cotas diferentes utilizando a água como fluido referência, com viscosidade de 1,0 cP e também uma solução de açúcar a 1,2 cP. A unidade consistiu de um tanque de alimentação de 162,5 L construído em acrílico, uma bomba centrífuga com diâmetro do rotor de 200 mm acoplado a um motor em balanço de 2 CV de potência nominal, um inversor de freqüência para controlar a rotação do motor, tubulações de PVC transparentes de 1 in. de diâmetro nominal na descarga da bomba, um rotâmetro com escala de 0 - 12 m3/h, manômetro com escala 0 - 4 kgf/cm2, e dois tanques em acrílico de 72 L cada na descarga instalados em cotas diferentes. A unidade experimental que operou em regime permanente permitiu a verificação da vazão total e, por conseqüência, a determinação da vazão real em cada trecho ramificado. Os poucos trabalhos teóricos nesta área não comprovam experimentalmente a teoria, não analisam a influência de propriedades físicas e nem estimam a potência do motor. O experimento, portanto, procura comparar os dados coletados com a teoria utilizando fluidos com propriedades físicas diferentes. Este trabalho permitiu comparar os valores teóricos e experimentais com desvio de 12,5 a 20,5%, sendo proposta uma sequência teórica dividida em passos para a determinação do ponto de operação do sistema. O emprego desta sequência proposta permite reduzir os custos de instalação evitando malhas de controle, e os custos operacionais com a redução da energia consumida em sistemas industriais / Abstract: A centrifugal pump is a dynamic machine that can perform only on points on the head capacity curve or curve pump. Consequently, the sum of piping and components resistances during operation must fall exactly on the head capacity curve. The literature for the selection and specification of this equipment feeding only one point as a tank or vessel is large, however is hard to find studies regarding the simultaneous feeding of two or more tanks in different heights and showing the pressure behavior during process and the system curve. This simultaneously feeding is said branched. This study aimed to design and build a pilot-scale experimental unit to determine the system curve and the power consumption of a centrifugal pump when it feeds two tanks in different heights using in fluid viscosity of 1.0 cP, water as fluid reference as well sugar solution to 1.2 cP. The unit consisted of a feed tank of 162.5 L built in acrylic, centrifugal pump with a rotor diameter of 200 mm combined with a balance of motor 2 hp rated power, a frequency inverter to control the engine speed, PVC pipes in a transparent 1 in.nominal discharge of the pump, a flowmeter with a scale from 0 to 12 m3/ h, pressure gauge with a scale from 0 to 4 kgf/cm2, and two tanks of 72 L each in discharge also acrylic installed in different heights. The experimental unit that operated in steady state allowed the verification of the total flow and, consequently, the determination of actual flow in each passage branched. The few theoretical works in this area do not prove the theory experimentally, does not analyze the influence of physical properties and do not estimate the power of the engine. This work allowed us to compare the theoretical and experimental values with deviation of 12,5 to 20,5% being proposed after a theoretical split into steps for determining the operating point of the system. The use of this proposed sequence reduces installation costs by avoiding control loops, and operating costs by reducing the energy consumed in industrial systems / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química
84

Tank sizing from rainfall records for rainwater harvesting under constant demand

Allen, Jacqueline Elsa 17 April 2013 (has links)
M.Ing. (Civil Engineering Science) / In recent years, there has been an international trend towards installing rainwater tanks in an attempt to save water. However, there are no clear guidelines for determining the optimal size of such a tank in South Africa. This study investigates the possibility of simplifying the process of sizing a rainwater tank for optimal results. It utilises daily data from four rainfall stations, namely Kimberley, Mossel Bay, Punda Maria and Rustenburg, obtained from the South African Weather Services. The water use is considered to be for indoor purposes only, therefore assuming a constant daily demand to be extracted from the tank. The required size of a rainwater tank is influenced by the MAP, the area of the roof draining into the tank, the water demand (both the average demand and seasonal variations), the desired reliability of supply, and the rainfall patterns. The first step in simplifying the process is to consolidate the above variables. The tank volume is expressed as the number of days it could supply the average daily water demand. Another variable is created which provides the ratio of the total water volume which could theoretically be harvested from the roof in an average year, to the total water demand, from the tank, for a year. This has the effect of consolidating the MAP, the roof area, the water demand and the tank volume into two variables only and eliminates the need to consider numerous demand values. Using simulations over 16 years for each location, the relationships between these variables were determined to ensure 90%, 95% and 98% assurance of supply.
85

Experimental and Numerical Investigation of Liquid Storage Tanks Under Seismic Excitation

Bahreini Toussi, Iman January 2016 (has links)
Liquid storage tanks are a crucial type of structures. They are used to store various types of liquids and liquefied gases in different situations. In seismic regions, functionality of these structures after severe earthquakes is an important factor in their design. In earthquake-prone regions, the sloshing phenomena has an important role in the design procedure. Current design codes and guidelines (e.g. ACI 350.3 and ASCE 7) are based on analytical studies that in some cases can be inaccurate in prediction of forces and pressures. Since a long time ago scientists have studied the sloshing phenomena in liquid storage tanks with different methods including analytical, numerical and experimental studies. In the current study, rectangular ground-supported tanks are studied and the effect of seismic loading on them is investigated both experimentally and numerically. For the experimental tests, the tanks were placed on a shaking table and using high-speed HD cameras, tests were filmed and later analyzed frame by frame to capture the critical moments. To investigate the bi-lateral effect of base excitation on the tanks, they were oriented on the table with four different angles. In the numerical study, a computational fluid dynamics tool - OpenFOAM - was used to simulate the tank motion and finally the results were compared with the experiment in order to develop a reliable model.
86

Potencial de aproveitamento da água de chuva na produção de leite : um estudo de caso / Rainwater utilization of potencial in milk production : a case study

Santos, João Luis dos, 1968- 26 August 2018 (has links)
Orientadores: José Euclides Stipp Paterniani, Júlio Cesar Pascale Palhares / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-26T21:30:20Z (GMT). No. of bitstreams: 1 Santos_JoaoLuisdos_M.pdf: 2474199 bytes, checksum: e55fe5124e1e3d95564a8a55c50993f2 (MD5) Previous issue date: 2015 / Resumo: A escassez hídrica provocada pelo longo período de estiagem na região sudeste do Brasil, mais particularmente no estado de São Paulo, na região metropolitana, trouxe à tona, paradoxalmente, a ineficiência dos gestores públicos e a ausência de políticas que pudessem previnir os prejuízos decorrentes desse problema. Enquanto a Austrália e outros países possuem um amplo programa de uso da água de chuva, inclusive para consumo humano, no Brasil a técnica está segregada para população do nordeste, causando um preconceito sobre o tema em regiões onde, sempre se acreditou, haver disponibilidade hídrica eterna. Nesta pesquisa, um projeto de captação e uso da água de chuva foi montado em uma região de serra em Minas Gerais, na cidade de Inconfidentes, numa unidade de produção de leite, sendo monitorado e avaliado no período de outubro de 2013 a abril de 2014. Em todo período, típico para chuvas, já fica um alerta, menos da metade da precipitação esperada foi registrada. Ainda assim, na área de apenas 218 m² de captação haveria uma redução de consumo de 5% de toda água consumida, representando uma economia de pouco mais do 20 m³/mês da água nobre, retirada das nascentes e utilizadas para afastamento de dejetos, uma carga altamente poluidora. O volume de 20 m³/mês abasteceria com conforto uma família de 5 (cinco) pessoas. Com a Portaria MS 2914/11 como referência de qualidade da água para consumo humano, foram realizadas mais de 10 coletas e avaliadas em laboratório particular com Certificação NBR ISO 17025:2005- INMETRO. Os resultados demonstram que apenas a questão microbiológica deve ser uma preocupação prioritária. Mas, revelam ainda a necessidade de melhor investigação quanto a formação de THM na cloração da água de chuva. Com um sistema de cloração e filtração simples e de fácil operação foi possível atingir um padrão de qualidade seguro, sem colocar em risco a saúde mesmo no consumo indireto, como contato com a pele ou aspiração de gotículas de aspersão. A pesquisa propõe, ainda, estudo para a criação de uma regulamentação que classifique os tipos de água de chuva em função da região de captação bem como um plano para implantação do uso da água de chuva cumprindo etapas que passariam por um programa de monitoramento, um processo de tratamento e um sistema de captação e armazenamento / Abstract: Water scarcity caused by the long period of drought in southeastern Brazil, particularly in São Paulo metropolitan region brought up, paradoxically, the inefficiency of public officials and the absence of policies that could avoid the damage caused this problem. While countries like Australia, since there is ample rainwater use program including for human consumption, in Brazil the technique is restricted into the northeast population, causing a bias on the subject in regions wherever it was believed be water availability eternal. In this research a rain water harvesting project in a mountain region in Minas Gerais, in the city of Inconfidentes, a milk production unit, was evaluated from October 2013 to April 2014. In any period, typical for rain, it is a warning; there was less than half the expected rainfall. Still, in an area of 218m² only capture would be a 5% consumption reduction of all water consumed, representing a saving of little more than 20m³ / month of spring water, used for removal of waste, a highly pollutant load. The volume of 20m³ / month supplies comfort with a family of five people. With the Ordinance 2914 as water quality reference for human consumption, there were more than 10 collections and evaluated in a private laboratory with certification NBR ISO 17025:2005- INMETRO. The results show that only the microbiological matter must be a priority concern. Also, reveal the need for further investigation as the formation of THM in rainwater chlorination. With a simple chlorination and filtration system and easy operation was possible to achieve a standard of quality insurance without putting at risk the health even in indirect consumption, such as contact with the skin or suction spray droplets. The research also proposes to study the creation of a regulation which classifies types of rain water due to the capture region and a plan for rainwater use deployment fulfilling steps that would pass through a monitoring program, treatment process and capture and storage system / Mestrado / Agua e Solo / Mestre em Engenharia Agrícola
87

Integration of cryogenic tanks and fuel cells for future hydrogen-powered aircraft

Dannet, Grégoire January 2021 (has links)
Hydrogen is seen as the green fuel of the future for the aeronautical sector allowing to reduce the carbon footprint of commercial aviation. It is well established that the release of carbon emissions triggers global warming. Aviation, like many other industries, must reduce them. This study aims to integrate cryogenic hydrogen storage onboard an existing aircraft and study two different propulsion systems, namely hydrogen combustion and fuel cells. A cryogenic tank was modelled and then designed to fit in the fuselage of an A321. Two configurations were studied, one consisting of one tank at the rear and the other with two tanks, one at the front and one at the aft. The result showed a significant variation of the centre of gravity for the rear tank configuration, whether the airplane is empty or with payload. Among the two propulsion systems investigated, hydrogen combustion requires less of a technological leap than hydrogen fuel cell aircraft. The limitation would be the range due to the lack of volume onboard the aircraft to store the hydrogen fuel. But this new type of propulsion could lay the groundwork for future fuel cell aircraft. The fuel cells technology still needs to improve its power density to compete with current engines but would o er more efficient aircraft and therefore greater range.
88

Conformal Propellant Tanks and Vane Design

Robert Paul Beggs (11927936) 28 April 2022 (has links)
<p>Current small satellite propellant tank design is driven by three factors: volume op-timization, manufacturing capability, and propellant management. Conformal propellanttanks offer solutions to the design challenges of optimizing satellite volume and manufac-turing costs. Conformal propellant tank designs that meet these challenges have unknowneffects on propellant management. Compounding this uncertainty is the industry shift to-wards new green propellants with large contact angles. Improper propellant managementcan deliver gas to a thruster or leave propellant trapped away from the tank outlet whiledraining. Both scenarios reduce the lifespan of satellites.</p> <p>Stamping is one manufacturing process that can produce tanks that optimize volumeand are relatively easy to manufacture. The effects of the stamping process on tank shapeand propellant management is evaluated through testing four different tank geometries. Thestamping process sometimes leaves behind a seam where two sides of a tank are joinedtogether. A total of six tank and vane combinations are tested. One set of traditional tanksserve as a control. Three tanks tested share vane geometry and have different interiors toevaluate the effects of the stamping process on propellant management. The first tank hasa smooth interior, the second has a seam at the joints and the third tank has a seam andridges for increased stiffness. The last two tanks have an interior in the shape of an arc andhave different vanes. The experiment is flown on the ZeroG airplane to test the tank andvane designs in a weightless environment.</p> <p>The experiment consists of a payload rack, eleven experimental pods and one powerdistribution pod. Each experimental pod is designed to be modular and independent fromall other experimental pods. Each experimental pod hosts a camera, electrical box, secondcontainment and fluid system with four tanks.</p> <p>The results of this study show no discernible difference could be observed between tankswith or without a seam from the stamping process. When ridges are added to a tank thatare parallel to the contact line, liquid may not wick into the ridge if it is dry. If the ridgeis wet the liquid spreads out on the surface of the tank further. The differences betweenpropellant positioning for zero and nonzero contact angle fluids are discussed</p> <p><br></p>
89

La perméabilité des réservoirs à lisier en béton /

Denis, Jacques January 1989 (has links)
No description available.
90

Global Optimization of an Aircraft Thermal Management System through Use of a Genetic Algorithm

Allen, Christopher T. 26 September 2008 (has links)
No description available.

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