Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 109-115). Also available on the World Wide Web.

<p>Most of the heavy-duty machines, in particular construction vehicles, employ hydraulically actuated functions that are used to perform multiple tasks with elevated power requirements. Such high-power demand motivates the Original Equipment Manufacturers (OEMs) to minimize the costs associated with energy consumption through the design of such hydraulic systems. The human-machine interaction (human factors) and the efficiency of the hydraulic control system are considered key elements towards a successful design. The interaction between the operator and the machine considerably affects the performance of construction machines. In order to maintain high levels of productivity, the operators require comfort and effortless controllability of the multiple hydraulic functions. The comfort requirement can include limited shocks and oscillations while operating the machines (while driving and controlling the implement motion), cabin accessories (AC, radio, cameras, etc.) and accessibility to the instrumentation. Besides, the operators have to control multiple functions simultaneously in an efficient manner while maintaining high levels of productivity. Consequently, the operators require smooth controllability of such functions. Such demand can largely affect the efficiency of the expected hydraulic control system and can induce additional costs and complexity. The OEMs are therefore forced to find a balance between efficiency and operators’ requirements to be competitive on the market. As a result, the currently adopted hydraulic architectures rely on purely hydraulic components to ensure robustness and functionality of the hydraulic functions at the expenses of limited performance and high-power consumption. In this dissertation, electro-hydraulic components are employed to induce improvements of the commercially available solutions while still complying with the operators’ demands and energy efficiency. To this end, this work tackles the weaknesses of traditional hydraulic architectures and it proposes alternative solutions to overcome their limitations. Two full-size wheel loaders are used to study the behavior of the existing system and later to implement the proposed variations. First, the development of an innovative ride control feature to improve the operators’ comfort is presented. Experimental results show the proposed strategy having better comfort performances compared to the purely hydraulic solution. Besides, the electro-hydraulic alternative does not demand the costly additional components the commercial solution instead requires. Second, this work faces the concern for efficiency of the present hydraulic architecture. The most diffused hydraulic system for the studied category of construction machines, commonly known as Load Sensing (LS), is sized to work most efficiently for elevated power conditions. During this work, an electronically controlled hydraulic supply unit and a flow-sharing method are used to reduce the hydraulic power consumption in the regions where the traditional LS system is less efficient. With a simple and cost-effective modification, the presented control strategy can induce an efficiency improvement over a wide range of operating conditions. Third, this dissertation proposes an operator-assistance feature to potentially increase the overall productivity and reduce the operator’s stress. An online estimation algorithm was developed to predict the payload weight of the transported material inside the bucket and the pushing forces during a typical loading cycle. The calculated payload mass provides an estimate of the user’s productivity level and it is extremely advantageous when the loaded material should reach a certain target weight. The developed estimation algorithm can also support an optimized autonomous excavation process, which can progressively limit the operator-machine interaction.</p>

No description available.

Load sensing pumps in hydraulic system of wheel loaders helps in increasing the energy efficiency of wheel loaders. Present day machines have hydro mechanical load sensing system. After the advent of hydro mechanical load sensing concept, over the years, lots of research has been carried out relevant to electro hydraulic load sensing, trying to control the pump electronically. Currently, Volvo Construction Equipments (VCE) is interested in investigating the possibility of implementing electro hydraulic load sensing system in the wheel loaders. Research works has shown existence of several configurations of electro hydraulic load sensing pumps. Successful simulation results of an electro hydraulic load sensing pump configuration would provide a backing for the proposal of building and testing that configuration of electro hydraulic load sensing pump prototype. Also, the thesis work aims in benchmarking hydraulic system simulation capabilities of AMESim and GT- Suite by simulating the existing hydro mechanical load sensing system in both in both the simulation packages. / The thesis work has been carried out at Virtual Product Development (VPD) division of Volvo Construction Equipments (VCE), Eskilstuna, Sweden.

Submitted by Pedro Silva Filho (pfsilva@ipen.br) on 2017-11-17T17:27:31Z No. of bitstreams: 0 / Made available in DSpace on 2017-11-17T17:27:31Z (GMT). No. of bitstreams: 0 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Os elementos de combustível de um reator nuclear de pesquisa tipo MTR (\"Material Testing Reactor\") são, em sua grande maioria, formados por placas de combustível revestidas com alumínio contendo no cerne silicileto de urânio (U3Si2) disperso em matriz de alumínio. Essas placas possuem espessura da ordem de milímetros e comprimentos muito maiores em relação à sua espessura. Elas são dispostas paralelamente no conjunto que forma o elemento combustível, de maneira a formar canais entre elas com poucos milímetros de espessura, por onde escoa o fluido de refrigeração (água leve ou água pesada). Essa configuração, associada à necessidade de um escoamento com altas vazões para garantir o resfriamento das placas em operação, pode gerar problemas de falhas mecânicas das placas de combustível devido às vibrações induzidas pelo escoamento nos canais e, consequentemente, acidentes de proporções graves no caso de velocidade crítica que possa gerar o colapso das placas. Embora não haja ruptura das placas de combustível durante o colapso, as deflexões permanentes excessivas das placas podem causar bloqueio do canal de escoamento no núcleo do reator e levar ao superaquecimento nas placas. Para este trabalho, foram desenvolvidas uma bancada experimental com capacidade para altas vazões volumétricas (Q=100 m3/h) e uma seção de testes que simula um elemento combustível do tipo placa com três canais de resfriamento. A seção de testes foi construída com placas de alumínio e acrílico e foi instrumentada com sensores de deformação, sensores de pressão, um acelerômetro e um tubo de pitot. As dimensões da seção de testes foram baseadas nas dimensões do Elemento Combustível do Reator Multipropósito Brasileiro (RMB), cujo projeto está sendo coordenado pela Comissão Nacional de Energia Nuclear - CNEN. Os experimentos realizados alcançaram o objetivo de chegar à condição de velocidade crítica de Miller com o colapso das placas. A velocidade crítica foi atingida com 14,5 m/s levando a consequente deformação plástica das placas que formam o canal do escoamento. O canal central na entrada da seção de testes apresentou uma abertura de 3 mm em seu centro, causando um grande bloqueio do escoamento nos canais laterais. Este comportamento foi v constatado visualmente durante a desmontagem da seção de testes, ilustrado e discutido na análise de resultados apresentado neste trabalho. O bloqueio dos canais também foi observado por meio de gráficos de queda de pressão e por gráficos das deformações da entrada, centro e saída das placas contra a velocidade média da seção de testes. Observou-se uma queda da resistência hidráulica da seção de testes devido ao aumento da seção transversal de escoamento no canal central e um aumento exponencial das deformações quando da ocorrência da velocidade crítica. Comparativamente, o valor experimental obtido para velocidade crítica na seção de testes foi da ordem de 85% do valor obtido por cálculo com a expressão teórica de Miller. Os experimentos realizados permitiram um melhor entendimento da interação fluido estrutura em elementos de combustível tipo placa como: valores de frequências de vibrações naturais, instabilidade fluido elástica e desenvolvimento de técnicas para a detecção de valores de velocidade crítica. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP / CNPq:481193/2012-0

Due to the robustness and flexibility of hydraulic components, hydraulic control systems are used in a wide range of applications under various environmental conditions. However, the coverage of this broad field of applications often comes with a loss of performance. Especially when conditions and working points change often, hydraulic control systems cannot work at their optimum. Flexible electronic controllers in combination with techniques from the field of machine learning have the potential to overcome these issues. By applying a reinforcement learning algorithm, this paper examines whether learned controllers can compete with an expert-tuned solution. Thereby, the method is thoroughly validated by using simulations and experiments as well.

Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2016-08-26T12:15:03Z No. of bitstreams: 0 / Made available in DSpace on 2016-08-26T12:15:03Z (GMT). No. of bitstreams: 0 / O escoamento bifásico de gás-líquido é encontrado em muitos circuitos fechados que utilizam circulação natural para fins de resfriamento. O fenômeno da circulação natural é importante nos recentes projetos de centrais nucleares para a remoção de calor. O circuito de circulação natural (Circuito de Circulação Natural - CCN), instalado no Instituto de Pesquisas Energéticas e Nucleares, IPEN / CNEN, é um circuito experimento concebido para fornecer dados termo-hidráulicos relacionados com escoamento monofásico ou bifásico em condições de circulação natural. A estimativa de transferência de calor tem sido melhorada com base em modelos que requerem uma previsão precisa de transições de padrão de escoamento. Este trabalho apresenta testes experimentais desenvolvidos no CCN para a visualização dos fenômenos de instabilidade em ciclos de circulação natural básica e classificar os padrões de escoamento bifásico associados aos transientes e instabilidades estáticas de escoamento. As imagens são comparadas e agrupadas utilizando mapas auto-organizáveis de Kohonen (SOM), aplicados em diferentes características da imagem digital. Coeficientes da Transformada Discreta de Cossenos de Quadro Completo (FFDCT) foram utilizados como entrada para a tarefa de classificação, levando a bons resultados. Os protótipos de FFDCT obtidos podem ser associados a cada padrão de escoamento possibilitando uma melhor compreensão da instabilidade observada. Uma metodologia sistemática foi utilizada para verificar a robustez do método. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

La marée interne générée sur une topographie est un élément clé des transferts énergétiques des échelles de forçage de l'océan vers les échelles de mélange turbulent. Elle contribuerait à près de la moitié du mélange turbulent nécessaire au maintien de la stratification océanique. Une compréhension plus approfondie des processus mis en jeu est nécessaire pour décrire plus précisément son rôle dans le maintien de la circulation océanique. Cette thèse s'inscrit dans la continuité des travaux d'Y. Dossmann (2012) portant sur les ondes internes solitaires générées au dessus d'une dorsale océanique. Ces travaux reposent sur une utilisation complémentaire d'expériences physiques menées dans le grand canal du CNRM-GAME et d'expériences numériques à l'échelle du laboratoire effectuées avec le modèle d'océanographie côtière SNH. L'utilisation simultanée de ces deux outils a notamment permis d'évaluer la validité des hypothèses sous-jacentes de ce modèle et le développement de nouveaux schémas numériques. Dans cette thèse, des simulations numériques utilisant la version non-hydrostatique et non-Boussinesq du modèle SNH sont utilisées pour décrire les différents régimes d'ondes internes dans des régions " supercritiques ". Le terme supercritique désigne à la fois des courants de marée intenses dont la vitesse U est supérieure à la vitesse de propagation des ondes internes cn, et des topographies très abruptes dont l'angle de la pente est supérieur à l'angle du rayon d'onde interne dans la pycnocline . De telles conditions environnementales correspondent à des régions de mélange intense, jusqu'à 10 000 fois supérieur au mélange turbulent observé dans l'océan ouvert. Les processus physiques ayant lieu dans ces régions restent encore mal compris et mal représentés par les paramétrisations d'ondes internes existantes. De plus, ces régions sont également des zones propices à la génération d'ondes internes non-linéaires pouvant se propager pendant plusieurs jours et entraînant ainsi des transferts d'énergie significatifs loin de leur zone de génération. La description des processus turbulents en jeu dans ces régions " extrêmes " constitue le cœur de ma thèse. Dans une première partie, des configurations académiques à l'échelle du laboratoire sont mises en place pour étudier les processus en jeu dans différents régimes " supercritiques " de génération d'onde internes. Des simulations numériques directes sont réalisées et permettent d'identifier un nombre limité de paramètres physiques adimensionnés contrôlant la dynamique des ondes internes dans ces régions. Une attention particulière est portée sur le rôle joué par la topographie sur la génération des modes verticaux d'ondes internes et sur la formation de modes " hauts " d'ondes internes solitaires. Le second objectif de cette thèse est de faire le lien entre les précédentes études académiques à l'échelle du laboratoire et l'échelle océanique. Pour cela, un principe de similitude permettant de conserver la dynamique des ondes internes tout en modifiant l'échelle de l'écoulement est mise en place. Par le biais de ce principe de similitude, nous partons de cas idéalisés à l'échelle du laboratoire, que nous transposons à l'échelle océanique, pour nous rapprocher de cas océaniques plus réalistes et de plus en plus complexes. Puis notre étude de régime est étendue à deux régions océaniques " supercritiques " bien connues : le détroit de Gibraltar et le plateau situé à l'entrée du golfe du Maine (nommé " Georges Bank " en anglais). L'applicabilité de nos paramètres clés est étudiée dans le cas de ces deux environnements complexes par le biais de simulations haute résolution de grande échelle (LES). / Internal tides are involved in the Meridional Overturning Circulation energy balance. The issue about the relative importance of the mechanical and thermodynamical energy sources induces a need for a quantitative evaluation of the energy transfers and for a clear understanding of the physical processes involved in these energy transfers. In supercritical regions such as the strait of Gibraltar or the Hawaiian Ridge, large topography variations and strong currents lead to more complex generation mechanisms of internal waves and environmental interactions. They can be subject locally to spectacular breaking, with turbulent structures observed hundreds of meters above the seafloor, and driving turbulence orders of magnitude higher than open-ocean levels. These regions are also effective at generating nonlinear internal waves (ISWs) which persist for days after their generation and are suspected to be responsible for important remote energy transfers. In these "extreme" regions, ISWs dynamics is also more difficult to model. These situations are highly non-hydrostatic and non-linear with strong instabilities, strong velocity and density gradients and steep slopes. Moreover, in these regions, actual internal wave's parameterizations are often inadequate. So there is a real need to understand and represent better the ISWs dynamic in these areas. This thesis follows the line of research of Dossmann (2012), on topographically induced internal solitary waves which used a complementary approach relying on numerical and experimental configurations at laboratory scale. In this context, we continue to explore internal tide regimes but in "supercritical" regions: internal tide generation area with supercritical topography and hydraulic control. Simulations are performed using the nonhydrostatic and non-Boussinesq version of the regional oceanic circulation model SNH. In a first part, taking an idealized modeling approach at laboratory scale, we examined a range of different internal waves regimes in "supercritical" regions. Relying on quasi-direct numerical simulations (quasi-DNS), a regime analysis has been proposed using and identifying key non-dimensional parameters for ISWs dynamics. This analysis has permitted to recover a topographic control on vertical mode generation characterized by the ratio of vertical mode wavelength to topography width, even above supercritical topography. The topographic selection criterion has proven to be a useful indicator of high mode solitary wave formation in non-linear regime. The purpose of the second part is to extend the previous studies at laboratory scales towards more realistic oceanic conditions. In this regard, the regime analysis is applied to a idealized large scale oceanic strait through a similitude principle. The idealized strait configuration succeeds in representing laboratory scale strait regime at largest and realistic scales. Then our analysis is applied to two well-known realistic cases: the Strait of Gibraltar and Georges Bank through large eddy simulations. These two oceanographic "supercritical" regions are particularly interesting for their specific topography and stratification conditions.

<p>The electrification trend affecting off-road vehicles is paving the way toward dedicated electrified hydraulic actuation systems. Although traditional centralized fluid power architectures are still utilized in many applications for low cost, power density, and reliability, nowadays emission policy results in an increasing interest in developing electro-hydraulic actuator (EHA) solutions. EHAs enable non-throttling actuation and energy recuperation during overrunning loads, leading to higher transmission efficiency and lower fuel consumption. These features in energy efficiency make EHAs competitive in meeting emission regulations compared to conventional hydraulic solutions.</p> <p>The key challenge in developing the EHA solution comes from the high cost and space requirements, especially for the adoption of self-contained EHAs in mobile applications. In this study, two architectures for the EHA are proposed, a closed-circuit architecture and an open-circuit one, to determine the most practical and efficient configuration. The most effective open-circuit architecture with distributed concepts is further investigated for implementation, which requires less modification of the mechanical structures and performs more efficiently than the closed-circuit alternative. The proposed EHA is driven by an electro-hydraulic unit (EHU) consisting of a variable-speed electric motor and a fixed-displacement hydraulic pump, which is relatively cost-effective. A novel hydraulic configuration is proposed, which allows the EHA to cover full-speed operating ranges in four quadrants. </p> <p>To verify the EHA design, the behavior of the proposed system should be predicted prior to costly experiments and demonstrations. For this purpose, an integrated simulation model is developed based on the lumped parameter approach in the Amesim environment. The model includes the electric system, the hydraulic system, and the mechanism to be implemented, which are capable of flexible analysis of functionality, efficiency, and thermal performance.</p> <p>In this work, a dedicated test rig for EHA testing is developed. The test rig can help verify EHA performance, test the control algorithm, and diagnose errors before implementing the system on real applications. The experimental results from the test rig also validate the simulation model. An independent load drive of the test rig allows testing all possible  loading conditions of the proposed EHA, thus demonstrating the energy performance in four quadrants. Thermal behavior is investigated with long duty cycles to determine the need for additional cooling equipment. After the validation of the hydraulic configuration, a power electronics setup is added to the test rig, which allows to drive the EHA system with the novel designed EHUs. Validation on the test platform paves the way for implementation in a vehicle. </p> <p>As a final step, the proposed EHA system is implemented in a reference vehicle, a Case New Holland TV380 skid steer loader. A novel designed EHU is adopted to drive the system for technology demonstration. The energy savings capacity of the EHA is investigated in comparison to the baseline measurements of the traditional open-center hydraulic architecture. The impressive savings from the reduction of throttling losses and energy recovery guide the possible commercialization of such EHAs in mobile hydraulic applications. The controller design of the implemented EHA system is investigated with the aim of improving the dynamic performance, e.g., reducing damping oscillation. Basic power management strategies are also studied to integrate EHA with the power train of current hydraulic machines. Regarding future work, based on this research but not within the scope of this study, the proposed EHA system can be adopted with different types of prime movers, such as axial piston machines as the hydraulic part of an EHU. Furthermore, the design approach proposed in this study can help resize the EHA system for other applications with different loading conditions and power requirements, and the energy savings capability can be further investigated. With this, a comprehensive market analysis will be performed for the commercialization of EHA. </p>

Det här arbetet ger en orientering i växters olika förmågor att rehabilitera miljöskador och belyser möjligheten att använda växternas essentiella och varierande förmågor i miljöarbetet. De ämnen som har skadlig inverkan på miljön kallas för miljögifter. Både globalt och i Sverige har omloppet av många miljögifter ökat markant de senaste århundradet. Växter kan användas för att rena förorenad mark. De olika processerna när växter renar mark, vatten och luft från föroreningar samlas under begreppet fytoremediering. Det finns olika metoder och reningsprocesser inom fytoremediering. Växter kan dels ta upp och lagra föroreningar, bryta ned dem till ofarliga beståndsdelar samt förhindra så att de inte sprider sig ut i ekosystemet. I det här examensarbetet har föroreningssituation vid järnvägsstationen i Ockelbo använts som exempel för att konkretisera fytoremediering till en specifik plats. En beskrivning av de till platsen relaterade föroreningarna arsenik, bly, kadmium, kvicksilver, koppar, zink, PAH (polycykliska aromatiska kolväten) och olja presenteras tillsammans med aktuella fytoremedieringsmetoder och grödor för respektive förorening. Som slutsats bedöms fytoremediering vara möjligt för järnvägsstationen i Ockelbo. Fördelar och nackdelar med fytoremediering på stationen lyfts fram och möjliga parallella användningsområden medan fytoremedieringen pågår diskuteras. Vidare diskussion förs kring fytoremediering, miljöfrågor och rådande regelverk och logistik i Sverige. Arbetet innefattar ett förslag till utformning av fytoremediering på stationsområdet. Förslaget inkluderar ett växtval av olika fytoremedieringsgrödor lämpliga för platsen.