Increasing population, diminishing supplies and variable climatic conditions can cause difficulties in meeting water demands. When this long range water supply plan is developed to cope with future water demand changes, accuracy and reliability are the two most important factors. To develop an accurate model, the water supply system has become more complicated and comprehensive structures. Future uncertainty also has been considered to improve system reliability as well as economic feasibility.In this study, a general large-scale water supply system that is comprised of modular components was developed in a dynamic simulation environment. Several possible scenarios were simulated in a realistic hypothetical system. In addition to water balances and quality analyses, construction and operation of system components costs were estimated for each scenario. One set of results demonstrates that construction of small-cluster decentralized wastewater treatment systems could be more economical than a centralized plant when communities are spatially scattered or located in steep areas.The Shuffled Frog Leaping Algorithm (SFLA), then, is used to minimize the total system cost of the general water supply system. Decisions are comprised of sizing decisions - pipe diameter, pump design capacity and head, canal capacity, and water/wastewater treatment capabilities - and flow allocations over the water supply network. An explicit representation of energy consumption cost for the operation is incorporated into the system in the optimization process of overall system cost. Although the study water supply systems included highly nonlinear terms in the objective function and constraints, a stochastic search algorithm was applied successfully to find optimal solutions that satisfied all the constraints for the study networks.Finally, a robust optimization approach was introduced into the design process of a water supply system as a framework to consider uncertainties of the correlated future data. The approach allows for the control of the degree of conservatism which is a crucial factor for the system reliabilities and economical feasibilities. The system stability is guaranteed under the most uncertain condition and it was found that the water supply system with uncertainty can be a useful tool to assist decision makers to develop future water supply schemes.

Depuis quelques années, les exigences des occupants de bâtiments ont sensiblement changé. On observe en effet une demande de confort de plus en plus rigoureux en particulier en période estivale. Cette augmentation des besoins de climatisation induit un accroissement important de la consommation d'énergie électrique dans les bâtiments, dû à une utilisation majoritaire de climatiseurs à compression mécanique de vapeur. Dans ce contexte énergétique difficile, les systèmes de rafraîchissement solaire font partie des alternatives intéressantes aux systèmes de climatisation classiques, dans la mesure où l'énergie primaire est principalement consommée sous forme de chaleur et provenant du soleil donc gratuite. L'autre grand intérêt de ces procédés est que le besoin en rafraîchissement coïncide la plupart du temps avec la disponibilité du rayonnement solaire. La compréhension et le développement de cette technologie passent par une étude expérimentale avec la réalisation d'installations pilotes à échelle réelle dans le but d'acquérir une expérience concrète. C'est dans ce sens que notre laboratoire s'est proposé de mettre en place une plateforme expérimentale d'une puissance frigorifique de 30 kWf chargée de rafraîchir des locaux d'enseignement de l'Institut Universitaire Technologique de Saint Pierre à La Réunion. La première partie de ce manuscrit présente une analyse expérimentale de cette installation. Une seconde approche purement fondamentale a été envisagée avec l'élaboration de modèles numériques permettant de prédire le comportement de l'installation dans son ensemble. Ces modèles numériques décrits sous plusieurs niveaux de finesse, sont validés par les données expérimentales avant d'être utilisés, soit comme outils de pré‐dimensionnement pour les modèles à descriptions simplifiés, soit comme outil d'optimisation et d'analyse pour les modèles détaillés. Le modèle détaillé représentant notre plateforme expérimentale a permis de réaliser une optimisation du fonctionnement de l'installation et de proposer des améliorations pour réduire la consommation d'électricité et augmenter le coefficient de performance électrique global. / In the last few years, thermal comfort research in summer has significantly increased the electricity consumption in buildings. This is mainly due to the use of conventional air conditioning systems operating with mechanical vapor compression. Solar cooling systems applied to buildings is an interesting alternative for reducing energy consumption in traditional mechanical steam compression air conditioning systems. But the understanding of this technology has to be refined through experimental study by setting up pilot plants. This study is a practical method to gain experience by analyzing all the processes behind solar cooling technology. For that purpose, our laboratory decided to install a solar cooling absorption system implemented in Reunion Island, located in the southern hemisphere. The particularity of this project is to achieve an effective cooling of classrooms, by a solar cooling system without any backup systems (hot or cold). The first part of this work presents an experimental study of this installation. Moreover, the study of these systems should have a closely purely fundamental approach including the development of numerical models in order to predict the overall installation performance. The final objective is to estimate cooling capacity, power consumption, and overall installation performance with relation to outside factors (solar irradiation, outside temperature, building loads). These numerical models described in several levels of accuracy, are validated by experimental data before being used either as tools for pre‐sizing models with simplified descriptions, either as a tool for optimization and analysis for the detailed models. The detailed model describing our experimental platform is used to carry out an optimization of pilot plant operation and to propose improvements to reduce electricity consumption and increase the overall electrical performance coefficient.

A pasteurização é um processo térmico para inativar micro-organismos patogênicos e deterioradores em alimentos líquidos. O controle do processo é fundamental para a manutenção da temperatura de pasteurização, de forma que a modelagem dinâmica se torna útil no desenvolvimento, nos testes de controladores e nos procedimentos de operação. O objetivo deste trabalho foi o desenvolvimento e a validação experimental da modelagem dinâmica de um pasteurizador a placas com três seções de troca térmica para estudar sua operação em regime transiente. A modelagem consiste em balanços diferenciais de energia entre canais e placas do trocador, perda de calor para o ambiente do tubo de retenção e conexões e as respectivas condições iniciais e de contorno. Os coeficientes de troca térmica do equipamento foram determinados experimentalmente. Na simulação foram adotados métodos de diferenças finitas e a resolução matemática foi realizada através do software gPROMS. O modelo foi aplicado para representar o comportamento de um pasteurizador a placas de escala laboratorial (Armfield FT43A), operando em duas condições: sem e com a influência da incrustação na seção de aquecimento do trocador. Para a validação do modelo foram realizados ensaios experimentais da partida e de perturbação das vazões de alimentação do processo. Foram inseridos termopares em diversos pontos do equipamento e as temperaturas foram registradas com um sistema de aquisição de dados. Para estudar a influência da incrustação na pasteurização, foram realizados ensaios experimentais com dois tipos de leite para se ter alta e baixa incrustação. As placas do trocador foram pesadas e fotografadas antes e depois dos ensaios de incrustação para avaliar o depósito formado. Foram utilizados modelos genéricos de incrustação para a simulação desse efeito sobre o processo de pasteurização. Através da comparação dos resultados experimentais e simulados foi verificada que a modelagem matemática para a operação transiente do processo de pasteurização analisado foi muito satisfatória. / Pasteurization is a thermal process used to inactivate pathogenic and deteriorative microorganisms in liquid foods. Process control is essential for the temperature maintenance of pasteurization, so that the dynamic model is an important tool in the development, controller tests, and also in the procedure of operation. The aim of this work was the development and experimental validation of the dynamic model of a plate pasteurizer with three sections of heat exchange studying the transient state operation. The model consists of differential equations of thermal energy balance between channels and plates of heat exchanger, heat loss to the environment of the holding tube and connections and their respective initial and boundary conditions. The heat transfer coefficients of plate heat exchanger and tubes were determined experimentally. In the simulation, finite difference methods were adopted and the math solving was performed using the gPROMS software. The model was applied to represent the behavior of a plate pasteurizer in laboratory scale (Armfield FT43A), operating in two conditions: free of fouling and with fouling influence on the heating section of the heat exchanger. Experimental tests of the start-up and of disturbances in flow rates of the process were performed for the model validation. Thermocouples were inserted at various points of the equipment and the temperatures were recorded with a data acquisition system. In order to study the influence of the fouling, experimental tests were performed with two kinds of milk to obtain high and low fouling. Plates of the heat exchanger were weighed and photographed before and after of the fouling tests for evaluate the deposit formed. Generic models of fouling were used to simulate the effect of fouling on the pasteurization process. Through the comparison of experimental and simulated results, it was verified that the mathematical modeling for the transient operation of the pasteurization process was very satisfactory.

A ventilação natural é uma das estratégias mais eficientes para o condicionamento térmico passivo de edificações, ocorrendo por ação dos ventos, por efeito chaminé ou pela combinação de ambos. Em áreas densamente ocupadas, a velocidade do vento é reduzida pelos diversos obstáculos locais, tornando o efeito chaminé e a captação pela cobertura as alternativas mais viáveis para indução da ventilação natural em edificações. Dentre as estratégias de ventilação, destacam-se os sheds, aberturas no telhado, que funcionam como captadores ou extratores de ar, dependendo de sua localização em relação aos ventos dominantes. Apesar de terem um grande potencial, são pouco utilizados devido à falta de dados técnicos acessíveis ao projetista. Além disso, muitas vezes são utilizados para captação ou para extração do ar de forma aleatória, sem uma análise da influência dos parâmetros projetuais na ventilação natural. Essa pesquisa parte da hipótese que existe diferença nesses parâmetros para um shed extrator e para um shed captador de ar e que é possível otimizar a ventilação natural através desses dispositivos. O objetivo geral foi avaliar o impacto de diferentes parâmetros projetuais e climáticos no desempenho de sheds captadores e extratores de ar e propor diretrizes para o projeto desses dispositivos. A metodologia foi composta de estudos paramétricos, a fim de investigar a interdependência de diferentes parâmetros projetuais na ventilação natural por sheds e realizar análises comparativas. O processo baseou-se em análises numéricas através de simulações CFD e a verificação desses resultados por meio de ensaios experimentais em túnel de vento. As análises mostraram uma boa compatibilidade entre os resultados numéricos e experimentais, obtendo uma diferença de no máximo 10% entre as duas ferramentas para a maioria dos pontos monitorados. Com relação às simulações computacionais, constatou-se que o desempenho de sheds é fortemente influenciado pela velocidade e pelos ângulos de incidência dos ventos externos. Além disso, notou-se que existem diferenças nos parâmetros projetuais para um shed extrator e para um captador, sendo que alguns casos apresentaram bons desempenhos em ambas as situações. Por fim, conclui-se que é possível otimizar o uso da ventilação natural através desses dispositivos, sendo que esses resultados auxiliam a prática do projeto arquitetônico na determinação de configurações adequadas. / Natural ventilation is one of the most important strategies for passive cooling of indoor environments. It can occur by wind forces, stack effect or a combination of both strategies. In urban areas the wind speed is reduced due to several obstacles. Stack effect and air intake by the roof can be viable alternatives to induce natural ventilation in buildings. Among the ventilation strategies, sheds can be highlighted. These structures consist of roof openings that work as collectors or extractors of air, depending on their location in relation to the prevailing wind directions. Although they have great potential, they are seldom used by Brazilian architecture, due to lack of technical data available to the designer. Besides, sometimes the sheds are used for air intake or exhaustion without any detailed analysis on the influence of different building design parameters on natural ventilation. The starting hypothesis of this research is that there is a difference in construction parameters for an exhaustion and intake sheds and it is possible to optimize the use of natural ventilation through these devices. The research aims to investigate the potential of air extracting and capturing sheds to promote indoor natural ventilation and proposes guidelines for the design of these devices. The applied methodology consists on parametric studies to investigate the interdependence of different design parameters for natural ventilation in sheds and perform comparative analyzes. The procedure was based on CFD simulations and the verification of such results through experimental tests using wind tunnel. The analyses showed a good compatibility between the numerical and experimental results, obtaining a maximum difference of 10% between the two tools for most of the monitored points. The computer simulations showed that sheds performance is strongly influenced by the external wind speed and its incidence angles. In addition, it was noted that there are differences in design parameters for air extracting and capturing sheds and some cases showed a good performance in both situations. Finally, it was concluded that it is possible to optimize the use of natural ventilation through these devices, and these results support the practice of architectural design in determining appropriate settings.

Esse trabalho investiga o impacto do comportamento transitório e em regime permanente da carga sobre a estabilidade de tensão do sistema elétrico. Para isso, utiliza-se uma modelagem detalhada da rede elétrica, capaz de representar os principais eventos inerentes aos fenômenos de instabilidade e colapso de tensão. A simulação numérica do sistema algébrico-diferencial resultante é realizada utilizando-se o solver DASSLC. Ao final desse trabalho, faz-se uma análise da resposta dos diferentes modelos de carga sobre a estabilidade de tensão do sistema de 14 barras do IEEE. / This work investigates the impact of transient and steady state load behavior on power systems voltage stability. In order to do this, a detailed electric power system model is used to reproduce the main aspects of voltage instability and collapse phenomena. The numerical solution of the resulting non-linear differential-algebraic equations is carried out by using the DASSLC solver. An analysis of different load models behaviour for some voltage instability situations is presented for IEEE 14 bus system.

Esse trabalho investiga o impacto do comportamento transitório e em regime permanente da carga sobre a estabilidade de tensão do sistema elétrico. Para isso, utiliza-se uma modelagem detalhada da rede elétrica, capaz de representar os principais eventos inerentes aos fenômenos de instabilidade e colapso de tensão. A simulação numérica do sistema algébrico-diferencial resultante é realizada utilizando-se o solver DASSLC. Ao final desse trabalho, faz-se uma análise da resposta dos diferentes modelos de carga sobre a estabilidade de tensão do sistema de 14 barras do IEEE. / This work investigates the impact of transient and steady state load behavior on power systems voltage stability. In order to do this, a detailed electric power system model is used to reproduce the main aspects of voltage instability and collapse phenomena. The numerical solution of the resulting non-linear differential-algebraic equations is carried out by using the DASSLC solver. An analysis of different load models behaviour for some voltage instability situations is presented for IEEE 14 bus system.

<p>VIRTUAL PROTOTYPING has been generally adopted in product development in order to minimise the traditional reliance on testing of physical prototypes. It thus constitutes a major step towards solving the conflict of actual increasing development cost and time due to increasing customer demands on one side, and the need to decrease development cost and time due to increasing competition on the other. Particularly challenging for the off-road equipment industry is that its products, working machines, are complex in architecture. Tightly coupled, non-linear sub-systems of different technical domains make prediction and optimisation of the complete system’s dynamic behaviour difficult.</p><p>Furthermore, in working machines the human operator is essential for the performance of the total system. Properties such as productivity, fuel efficiency, and operability are all not only dependent on inherent machine properties and working place conditions, but also on how the operator uses the machine. This is an aspect that is traditionally neglected in dynamic simulations, because the modelling needs to be extended beyond the technical system.</p><p>The research presented in this thesis focuses on wheel loaders, which are representative for working machines. The technical system and the influence of the human operator is analysed, and so-called short loading cycles are described in depth. Two approaches to rule-based simulation models of a wheel loader operator are presented and used in simulations. Both operator models control the machine model by means of engine throttle, lift and tilt lever, steering wheel, and brake only – just as a human operator does. Also, only signals that a human operator can sense are used in the models. It is demonstrated that both operator models are able to adapt to basic variations in workplace setup and machine capability. Thus, a “human element” can be introduced into dynamic simulation of working machines, giving more relevant answers with respect to operator-influenced complete-machine properties such as productivity, fuel efficiency, and operability already in the concept phase of the product development process.</p> / ISRN/Report code: LiU-Tek-Lic 2005:44

Remote communities, characterized by no connection to the main power grid, traditionally get their power from diesel generators. Long geographical distances and lack of suitable roads make the fuel transportation difficult and costly, increasing the final cost of electricity. A microgrid using renewable energy as the main source can serve as a viable solution for this problem with considerable economical and environmental benefits. The focus of this research is to develop a microgrid for a remote community in northern Ontario (Canada) that combines wind, as a renewable source of energy, and a hydrogen-based energy storage system, with the goal of meeting the demand, while minimizing the cost of energy and adverse effect on the environment. The existing diesel generators remain in the system, but their use is minimized. The microgrid system studied in this research uses a wind turbine to generate electricity, an electrolyser to absorb the excess power from the wind source, a hydrogen tank to store the hydrogen generated by the electrolyser, a fuel cell to supply the demand when the wind resource is not adequate, and a diesel generator as a backup power. Two scenarios for unit-sizing are defined and their pros. and cons. are discussed. The economic evaluation of scenarios is performed and a cost function for the system is defined. The optimization problem thus formulated is solved by solvers in GAMS. The inputs are wind profile of the area, load profile of the community, existing sources of energy in the area, operating voltage of the grid, and sale price of electricity in the area. The outputs are the size of the fuel cell and electrolyser units that should be used in the microgrid, the capital and running costs of each system, the payback period of the system, and cost of generated electricity. Following this, the best option for the microgrid structure and component sizes for the target community is determined. Finally, a MATLAB-based dynamic simulation platform for the system under study with similar load/wind profile and sizing obtained in optimization problem is developed and the dynamic behaviour of microgrid at different cases is studied.

The omnipresent tendency to &ldquo / live easy&rdquo / is a sign of our need for automatization. To enable for such a &ldquo / comfortable and safe&rdquo / world, the automatic systems have to be developed that satisfies the necessities of life. Biologically inspired robots, especially the humanoids, are thus the key, and research in this area focuses on the improvement of such systems. Lately, it has been shown by high dexterity examples that the humanoid robots achieved to a mature level even if there are still open issues to be improved, especially in the control and stability of the bipeds. The purpose of this thesis is to study biped locomotion in different floor conditions, such as stairs and obstacles / to improve the research done in this area / to contribute to the development of autonomous biped robots, dynamic modeling, gait planning, supervisory and guidence control, stability analysis of biped robots / and to implement new control algorithms for biped locomotion, especially by using optimization and high level intelligent control techniques. The locomotion aimed to be realized results from complex, high-dimensional, nonlinear and dynamically related interactions between the robot and its environment. The mathematical modeling of the physical system is realized based on a 5-link 7 DOF biped robot model walking on a 3D planar surface and the dynamic simulation is performed using MATLAB. In terms of control, several different methods applied, comparison and the performance of each method are given. The 3D dynamic simulation software is developed, which allows the user to operate the biped systems within a 3D virtual environment.

There is a considerable scope for improving the temperature control of exothermic processes. In this thesis, a sub-optimal control strategy is developed through utilizing the dynamic, simulation tool. This scheme is built around easily obtained knowledge of the system and still retains flexibility. It can be applied to both exothermic batch and fed-batch processes. It consists of servo and regulatory modes, where a Generalized Predictive Controller (GPC) was used to provide self-tuning facilities. The methods outlined allow for limited thermal runaway whilst keeping some spare cooling capacity to ensure that operation at constraints are not violated. A special feature of the method proposed is that switching temperatures and temperature profiles can be readily found from plant trials whilst the addition rate profile Is capable of fairly straightforward computation. The work shows that It is unnecessary to demand stability for the whole of the exothermic reaction cycle, permitting a small runaway has resulted in a fast temperature response within the given safety margin. The Idea was employed for an exothermic single Irreversible reaction and also to a set of complex reactions. Both are carried out in a vessel with a heating/cooling coil. Two constraints are Imposed; (1) limited heat transfer area, and (11) a maximum allowable reaction temperature Tmax. The non-minimum phase problem can be considered as one of the difficulties in managing exothermic fed-batch process when cold reactant Is added to vessel at the maximum operating temperature. The control system coped with this within limits, a not unexpected result. In all cases, the new strategy out-performed the conventional controller and produced smoother variations in the manipulated variable. The simulation results showed that batch to batch variations and disturbances In cooling were successfully handled. GPC worked well but can be susceptible to measurement noise.