.Les think tanks sont des acteurs qui s’inscrivent dans une perspective d’information et d’influence. A travers des expertises et des recommandations politiques, ils cherchent à atteindre la sphère politique. Bien qu’ils soient majoritairement apparus en Europe dans les années 1970 et 1980 et que leur essor date des années 2000, les think tanks sont des acteurs émergents dans le processus décisionnel européen. Ils ont rapidement su se saisir des différents points d’accès proposés par les institutions européennes et sont progressivement devenus des acteurs incontournables et influents dans le processus décisionnel européen. Les cibles d’action sont plus précisément la Commission européenne, le Parlement européen, le Comité des Régions ainsi que le Comité Economique et Social Européen. Les modalités et les stratégies d’influence mises en place par les think tanks pour atteindre ces institutions et organes prennent des formes variées. / .Think tanks are actors that are part of a didactic and influence perspective. Through expertise and political recommendations, they seek to reach the political sphere. Although most of them emerged in Europe in the 1970s and 1980s and their growth began in the 2000s, think tanks are emerging players in the European decision-making process. They quickly managed to seize the various access points proposed by the European institutions and gradually became key and influential actors in the European decision-making process. The action targets are more specifically the European Commission, the European Parliament, the Committee of the Regions and the European Economic and Social Committee. The modalities and strategies of influence put in place by the think tanks to reach these institutions and organs take various forms.

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Master of Science / Department of Mechanical Engineering / Donald Fenton / The need to store and access electronic information is growing on a daily basis as more and more people conduct business and personal affairs through email and the internet. To meet these demands, high energy density data centers have sprung up across the United States and around world. To ensure that vital data centers run constantly, proper cooling must be maintained to prevent overheating and possible server damage from occurring. Emergency cooling systems for such systems typically utilize traditional batteries, backup generator, or a combination thereof. The electrical backup provides enough power to support cooling for essential components within the data centers. While this method has shown to be reliable and effective, there are several other methods that provide reliable emergency cooling at a fraction of the cost. This paper address the lack of information regarding the initial, operation, and maintenance costs of using Thermal Energy Storage (TES) tanks for emergency cooling. From research and various field examples, five emergency cooling system layouts were designed for various peak cooling loads. Looking at the different cooling loads, components, and system operations an economic evaluation of the system over a 20 year period was conducted. The economic analysis included the initial and maintenance costs of each system. In an effort to better understand power consumption of such systems and to help designer’s better estimate the long term costs of TES tanks systems, five layouts were simulated through a program called TRNSYS developed for thermal systems. To compare against current systems in place, a benefit to cost ratio was done to analyze TES versus a comparable UPS. The five simulated systems were one parallel pressurized tank, one parallel and one series atmospheric tank, one parallel low temperature chilled water, and one series ice storage tank. From the analysis, the ice storage and pressurized systems were the most cost effective for 1 MW peak cooling loads. For 5 MW peak cooling loads the ice storage and chilled water systems were the most cost effective. For 15 MW peak loads the chilled water atmospheric TES tanks were the most cost effective. From the simulations we concluded that the pressurized and atmospheric systems consumed the least amount of power over a 24 hour period during a discharge and recharge cycle of the TES tank. From the TRNSYS simulations, the ice storage system consumed 22 – 25% more energy than a comparable chilled water system, while the low temperature storage system consumed 6 – 8% more energy than the chilled water system. From the benefit-cost-ratio analysis, it was observed that all systems were more cost effective than a traditional battery UPS system of comparable size. For the smaller systems at 1 MW the benefit-cost-ratio ranged between 0.25 to 0.55, while for larger systems (15 MW) the ratio was between 1.0 to 3.5 making TES tanks a feasible option for providing emergency cooling for large and small systems.

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.

Deviations from ideal flow and settling occur in circular wastewater treatment tanks because of tank geometry, flow conditions, and density currents caused by variations in suspended solids concentration and temperature distributions. Thermally induced density currents were investigated in this study. Under winter, low flow conditions, measurements were made of vertical and radial temperature distributions in the circular chlorination tank at Lake Oswego, Or., and in the circular primary and secondary clarifiers at Bend, Or. Thermistor arrays were used to collect the data which exhibited both vertically well-mixed and a two-layer flow regime. Inlet geometry and suspended solids in the secondary clarifiers caused a warm bottom inflow and apparent thermal instability. Meteorological measurements were also made. The calculated winter heat loss values indicated that convective mixing may have inhibited particle sedimentation in the clarifiers.

The object with this project is to develop a more accurate way to measure the level in the fuel tank in Scaniavehicles. The level should be displayed for the driver and a warning system be implemented to make the driveraware if the fuel level is too low. Furthermore a main goal is to develop an estimation of the distance that thevehicle could travel before refueling is needed.The fuel level estimation system is modeled using Matlab Simulink and simulated with measurement datacollected from real driving scenarios. After evaluating the system it is implemented in one of the electricalcontrol units located on a test vehicle which communicates with other systems. After implementation more testsare performed with the test vehicle to verify that the same functionality achieved during simulations is achievedusing the system implemented in a vehicle.The fuel level estimated with a KF (Kalman filter) that uses fuel consumption and level measurement results ingood performance. A more stable level estimate is achieved and a negative elevation of the estimate most of thetime, as a result of fuel use. Compared to the method Scania vehicles estimate their fuel level with today thenew level estimate is more steady and not that easily affected by fuel movements. The KF is more demanding interms of memory allocation, processor speed and inputs needed, which has to be considered when comparingboth methods. Another disadvantage with the KF is that it is dependent on the samples from the fuel levelsensor to get an initial estimate during startup.Furthermore the KF is easily expanded with more inputs that use information from other sensors on other parts of the vehicle.

Die Nutzung regenerativer Energiequellen stellt in vielen Systemen und Versorgungsnetzen wesentlich höhere Anforderungen an die Konstruktion, Auslegung und Betriebsführung von Wärmespeichern als konventionelle Energieträger. Aber auch das Potenzial eines Brennwertkessels kann mit einem optimierten Wasserwärmespeicher besser ausgeschöpft werden. Entscheidend für die Effizienzsteigerung von Wärmespeichern mit ausgeprägter thermischer Schichtung ist die Ausbildung und Aufrechterhaltung einer schmalen Mischzone zwischen dem wärmeren und kälteren Bereich des Speichers. Eine schmale Mischzone und eine niedrige Temperatur im unteren „entladenen“ Speicherbereich wirken sich positiv auf den Wirkungsgrad von Sonnenkollektoren und Brennwertkesseln aus. Beim Einsatz von Wärmepumpen verbessert sich deren Leistungszahl. Der Beitrag zeigt die Auswirkungen der Betriebsweise und der konstruktiven Details des Wärmespeichers, insbesondere der Be- und Entladevorrichtungen, auf, welche durch experimentelle und numerische Untersuchungen ermittelt wurden. / The spreading integration of renewable sources of energy into conventional heat supply systems places high demands on the designing, dimensioning and operation of hot water storage tanks. A pronounced thermal stratification is of positive influence for the efficiency of solar collectors, condensing boilers and the COP of heat pumps connected to the storage tank. The extent of the thermal mixing layer determines the volumetric efficiency of the tank and thus the economics of investment and operation. In this paper, a method is presented by which the losses of hot water storage tanks are correlated to the tank design and operating conditions.

<p>The object with this project is to develop a more accurate way to measure the level in the fuel tank in Scaniavehicles. The level should be displayed for the driver and a warning system be implemented to make the driveraware if the fuel level is too low. Furthermore a main goal is to develop an estimation of the distance that thevehicle could travel before refueling is needed.The fuel level estimation system is modeled using Matlab Simulink and simulated with measurement datacollected from real driving scenarios. After evaluating the system it is implemented in one of the electricalcontrol units located on a test vehicle which communicates with other systems. After implementation more testsare performed with the test vehicle to verify that the same functionality achieved during simulations is achievedusing the system implemented in a vehicle.The fuel level estimated with a KF (Kalman filter) that uses fuel consumption and level measurement results ingood performance. A more stable level estimate is achieved and a negative elevation of the estimate most of thetime, as a result of fuel use. Compared to the method Scania vehicles estimate their fuel level with today thenew level estimate is more steady and not that easily affected by fuel movements. The KF is more demanding interms of memory allocation, processor speed and inputs needed, which has to be considered when comparingboth methods. Another disadvantage with the KF is that it is dependent on the samples from the fuel levelsensor to get an initial estimate during startup.Furthermore the KF is easily expanded with more inputs that use information from other sensors on other parts of the vehicle.</p>

A suite of models were integrated to predict the potential of a large liquid hydrocarbon storage tank fire escalating and involving neighbouring tanks, as a result of thermal loading. A steady state pool fire radiant heat model was combined with a further model, in order to predict the distribution of thermal loading over the surface of an adjacent tank, and another model was incorporated to predict the thermal response of the contents of the adjacent tank. In order to predict if, or when, an adjacent tank will ignite, the radiant heat from the fire received by the adjacent tank must be quantified. There are a range of mathematical models available in the literature to calculate the radiant heat flux to a specified target and each of these models is based on assumptions about the fire. The performance of three of these models, which vary in complication, was analysed (the single point source model, the solid flame model and the fire dynamics simulator computational fluid dynamics model) and, in order to determine the performance of each model, the predictions made by each of the models were compared with actual experimental measurements of radiant heat flux. Experiments were undertaken involving different liquid fuels and under a range of weather conditions and, upon comparing the predictions of the models with the experimental measurements, the solid flame model was found to be the one most appropriate for safety assessment work. Thus, the solid flame model was incorporated into the thermal loading model, in order to predict the distribution of radiant heat flux falling onto an adjacent tank wall and roof. A model was developed to predict the thermal response of the contents of an adjacent tank, in order to predict variations in the liquid and vapour temperature, any increase in the vapour space pressure and the evolution of the vapours within the given time and the distribution of thermal loading over the surface of the tank as predicted by previous models; of particular importance was the identification of the possibility of forming a flammable vapour/air mixture outside the adjacent tank. To assess the performance of the response model, experiments were undertaken at both laboratory and field scale. The laboratory experiments were conducted in the Chemical Engineering Laboratory at Loughborough University and required the design and construction of an experimental facility representing a small-scale storage tank exposed to an adjacent fire. The field scale experiments were undertaken at Centro Jovellanos, Asturias, Spain. An experimental vessel was designed and fabricated specifically to conduct the laboratory tests and to measure the response of a tank containing hydrocarbon liquids to an external heat load. The vessel was instrumented with a network of thermocouples and pressure transmitter and gauge, in order to monitor the internal pressure and distribution in temperature throughout the liquid and its variation with time. The model predicting the thermal response of an adjacent tank was shown to produce predictions that correlated with the experimental results, particularly in terms of the vapour space pressure and liquid surface temperature. The vapour space pressure is important in predicting the time when the vacuum/pressure valve opens, while the liquid surface temperature is important as it governs the rate of evaporation. Combining the three models (the Pool Fire model, the Thermal Loading model and the Response model) forms the basis of the storage tanks spacing international codes and presents a number of innovative features, in terms of assessing the response to an adjacent tank fire: such features include predicting the distribution of thermal load on tanks adjacent to the tank on fire and thermal load on the ground. These models can predict the time required for the opening of the pressure vacuum relief valve on adjacent tanks and the release of the flammable vapour/air mixture into the atmosphere. A wide range of design and fire protection alternatives, such as the water cooling system and the minimum separation distance between storage tanks, can be assessed using these models. The subsequent results will help to identify any recommended improvements in the design of facilities and management systems (inspection and maintenance), in addition to the fire fighting response to such fires.

This is an investigation of the buckling characteristics of short, thin-walled cylinders. This study was required as large storage tanks, which were converted from Boating roof to fixed roofed tanks, were found to buckle when severe atmospheric temperature drops and thus pressure differentials occurred. These severe ambient temperature changes are characteristic of the Highveld in South Africa where the tanks in question are situated. Since this modification is an uncommon procedure, codes of practice for storage vessels do not cover this type of cylinder. For the same reason, research performed in this field is limited. Buckling due to axial loading, lateral external pressure, hydrostatic pressure and a combination of axial loading and hydrostatic pressure are explored in this study. To compare with and verify theory, existing research for each case is examined, and the Finite Element Analysis package MSC Nastran used to determine trends. In some cases, to the best of the author's knowledge, no research exists and numerical analysis is performed to establish the relationships present in those cases. The study is extended to include the design of imperfect cylinders, as defined in the tank code AD Merkblatter where it is stated as being dependant on the major and minor diameters of the imperfect section . The study is also extended to the case of variable wall thickness cylinders, where the thickness variation is symmetrical about the axis of the cylinder. / Thesis (M.Sc.)-University of Natal, Durban, 2001.