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Correia, Daniel Fortuna. "Management and Control of Water Supply Systems." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/13834.
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Mestrado em Engenharia MecânicaThe fast increase in the energy’s price has brought a growing concern about the highly expensive task of transporting water. By creating an hydraulic model of the Water Supply System’s (WSS) network and predicting its behaviour, it is possible to take advantage of the energy’s tariffs, reducing the total cost on pumping activities. This thesis was developed, in association with a technology transfer project called the E-Pumping. It focuses on finding a flexible supervision and control strategy, adaptable to any existent Water Supply System (WSS), as well as forecasting the water demand on a time period chosen by the end user, so that the pumping actions could be planned to an optimum schedule, that minimizes the total operational cost. The OPC protocol, associated to a MySQL database were used to develop a flexible tool of supervision and control, due to their adaptability to function with equipments from various manufacturers, being another integrated modular part of the E-Pumping project. Furthermore, in this thesis, through the study and performance tests of several statistical models based on time series, specifically applied to this problem, a forecasting tool adaptable to any station, and whose model parameters are automatically refreshed at runtime, was developed and added to the project as another module. Both the aforementioned modules were later integrated with an Graphical User Interface (GUI) and installed in a pilot application at the ADDP’s network. The implementation of this software on WSSs across the country will reduce the water supply companies’ running costs, improving their market competition and, ultimately, lowering the water price to the end costumer.
O rápido aumento dos preços da electricidade tem provocado um aumento na preocupação com a tarefa extremamente dispendiosa de transporte de água. Através da criação de modelos hidráulicos de redes de Sistemas de Fornecimento de Água, e da previsão do seu comportamento, é possível tirar vantagem das diferentes tarifas horárias de consumo de energia, reduzindo desta forma os custos totais do bombeamento de água. Esta tese foi desenvolvida em associação com o projecto de transferência de tecnologia denominado E-Pumping. Foca-se na procura de uma estratégia de supervisão e controlo flexível e adaptável a qualquer Sistema de Fornecimento de Água existente, bem como na previsão do consumo de água durante um período escolhido pelo utilizador final, o objectivo final é permitir o planeamento de um horário óptimo que minimize o custo do consumo de energia eléctrica. O Protocolo OPC, associado a uma Base de Dados MySQL, foi usado para o desenvolvimento da ferramenta de supervisão e controlo flexível, constituindo no seu conjunto um módulo do Projecto E-Pumping. A escolha baseou-se em ambas as tecnologias serem adaptáveis a equipamentos de diferentes fabricantes. Esta tese produziu ainda uma ferramenta de previsão do consumo de água, adaptável a qualquer estação, constituindo um segundo módulo do projecto. Esta ferramenta foi obtida através do estudo e testes de performance a variados modelos baseados em séries temporais, especificamente aplicadas a este problema. Os parâmetros do modelo de base desta ferramenta são automaticamente actualizados a cada execução do programa. Ambos os módulos referidos foram integrados com uma Interface Gráfica (GUI) e implementados numa aplicação piloto instalada na rede de abastecimento de água da empresa Águas do Douro e Paiva (ADDP). A implementação deste software em Sistemas de Abastecimento de Água por todo o país reduziria os seus custos de funcionamento, melhorando a sua capacidade de competição no mercado e, em última instância, diminuindo os preços da água para o consumidor final.
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Heinze, Alexander. "Modelling, simulation and control of a hydraulic crane." Thesis, Växjö University, School of Technology and Design, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-1932.
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The objective of this thesis is to develop a model that represents the dynamics of a hydraulically operated forestry crane. The model was derived with the traditional Euler-Lagrange formalism and considers the crane mechanics, three double-acting hydraulic cylinders and the valve control unit. On the basis of the derived model we reproduced the entire crane model in MATLAB in order to run simulations herewith. This gave us the possibility to do parameter changes for further studies of the crane in motion.
Another major goal within the thesis work was to estimate cylinder friction of the hydraulic actuators. We built up a test rig and used double-acting cylinders for determing their frictional behaviour. For this, we ran open-loop experiments in order to create velocity-friction maps that represented the static friction force of the cylinders. In this concern, we varied system pressure and cylinder load to study their influence on the friction force. By means of the derived static friction maps we approached the cylinder’s dynamic friction behaviour and applied both step and ramp control inputs to examine the spring-damping characteristics of the microspoic bristles in the contacting area. The dynamic friction experiments have been exerted in the fashion of the LuGre model. As a result we acquired different nominal friction parameters that we necessarily used to develope adequate friction models.
A third objective of this thesis was to establish a crane-tip control. Instead of a traditional control, providing a direct relationship between joystick input and cylinder extension, the focus was to build up a control for the end-effector’s trajectory in a two-dimensional frame. This could be achieved by using inverse kinematics in order to determine the required joint angles that corresponded to the desired position of the crane-tip.
The work also contains a CD including all developed MATLAB models that have been written within this project.
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Skjong, Stian. "Modeling, Simulation and Control of Hydraulic Winch System." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25578.
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In this thesis a hydraulic low pressure winch system has been modeled using bond graph theory. The hydraulic winch system is assumed to be installed on an offshore vessel affected by environmental forces and disturbances such as waves and currents. The hydraulic system powering the winch consists mainly of two pilot operated 3/3-directional valves controlled by two 4/3-directional valves and a hydraulic motor. The system also includes a pressure relief valve, check valves, pump systems, piping and filters. The 3/3-directional valves are the main focus in the model and are therefore modeled with less simplifications compared to the other subsystems. A thorough model study has been initiated to figure out the model limitations, sensitivity of model parameters and the ability to simplify the derived model without loosing essential dynamics and characteristics. The effects of variable bulk modulus and fluid inertia in the 3/3-directional valves have been studied by comparing different step responses and motor load characteristics. The observations and results from this model analysis laid the groundwork for control of the hydraulic motor. A clear relation between the main valve displacements and the motor velocity and torque in 4/3 valve configuration gave reasons to believe that manual motor control done by the winch operator through control of the valve displacements was possible. Adaptive PID controllers were used as inner controllers to control the control slides in the main valves. These controllers were later on replaced with PD-controllers when outer control was derived because the adaptive controllers tended to be a bit slow. Simplified state equations describing the motor dynamics were derived for control design purposes. The state equations extracted from the bond graph model showed high complexity, containing logic and discrete quantities, and were not suitable for control design. Model based speed- and torque controllers, based on sliding mode and backstepping control theory, were derived based on the simplified equations and implemented in the model. Different load cases were initiated to test the two controllers. A lumped wire-load model containing hydrodynamics, wire- and reel dynamics and environmental disturbances such as current and heave motions of the vessel were added in the total winch model to test the controllers in different operations with varying conditions and environments. The results from these controller tests gave reason to believe that a combination of these two controllers would be favourable in certain operations and would give increased safety in extreme cases such as stuck load and loss of load. The derived speed and torque controller were put into a hybrid controller framework and a switching algorithm was designed with focus on switching stability and wanted functionalities for the winch system. It was observed that switching stability and winch functionality were closely connected and different winch operations were essential in the design of the switching algorithm. Dwell time and tracking error switching were used as the main controller switching restrictions together with functionality based switching conditions. Different simulations were initiated to test the hybrid controller such as stuck load, loss of load and landing of a load at the sea floor. A Luenberger observer was derived to estimate the motor load and the motor velocity by using the simplified state equations and the differential pressure across the hydraulic motor as measurement in order to ensure redundancy in the control system and be able to control the hydraulic winch even though the decoder measuring the hydraulic motor velocity fails.
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Beard, Gregory Stuart. "Adaptive control of energy efficient hydraulic systems." Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266978.
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Sepehri, Nariman. "Dynamic simulation and control of teleoperated heavy-duty hydraulic manipulators." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30846.
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Some relevant aspects of dynamics and control of heavy-duty hydraulic machines in a teleoperated mode were investigated. These machines, such as excavators and forest
harvesters, are mostly used in primary industries. They have a manipulator-like structure with a nonlinear and coupled actuating system. The aim of the project is to investigate different approaches towards converting such machines, with minimum changes, into task-oriented human-supervisory control systems. This provides the opportunity
to use both human supervision and robotic power in hazardous environments and for tasks for which human decision is necessary.
A methodology was developed for fast and accurate simulations. Analytical, steady-state and numerical techniques were combined using Large-Scale Systems analysis. The inclusion of nonlinearities in the form of discontinuities (e.g., gear backlash and stick-slip friction) in the model was investigated. Numerical simplifications of the structural dynamics and alternative solutions for the hydraulic part were also studied.
The model describing the performance of the machine has been written in ACSL (Advanced Continuous Simulation Language) on a VAX computer system. A modified version of the program is at present running close to real-time on a single processor in conjunction with high speed graphics in a manner similar to a flight simulator used for human interface studies and training.
The model also evaluates the performance of the machine in a teleoperated mode and under different control strategies. As a result a velocity control algorithm has been developed which is applied in conjunction with the closed-loop components for teleoperation of heavy-duty hydraulic machines; it is basically a feedforward compensation
which uses the measured hydraulic line pressures along with fluid-flow equations as criteria
to control the joint velocities as well as to uncouple the interconnected actuating system. The control algorithm has been written in C language and is running on an IRONICS computer system, interfaced between the human operator and the machine. The simulation results are supported by the experimental evidence. The experiments were performed on a Caterpillar 215B excavator.
Improved operator safety, extension of human capability, job quality and productivity
increase are the advantages of a successful implementation of robotic technology to these industrial machines.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Glover, Peter Benedict Myers. "Computer simulation and analysis methods in the development of the hydraulic ram pump." Thesis, University of Warwick, 1994. http://wrap.warwick.ac.uk/66359/.
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The purpose of this study was primarily to promote the wider deployment of the hydraulic ram pump, and secondarily to provide the technical input into a programme aimed at using hydraulic ram pump technologies for third world development. Hitherto hydraulic ram pump technologies have been restricted by poor understanding of operational parameters, poor performance prediction, and poor design of pumps and installations. In pursuit of greater understanding the work utilised a computer simulation developed by the author as part of a previous research programme. This simulation was then greatly enhanced to provide improved accuracy and functionality. The enhanced simulation was then used to provide significant insight into the operation of a hydraulic ram pump and subsequently used to identify design improvements for the hydraulic ram pump. The simulation was used to investigate operational restrictions on the hydraulic ram, and was ultimately use to develop a model of hydraulic ram pump operation. The model of operation developed by the use of the simulation was computerised and used to predict the performance of hydraulic ram pump installations. This computerised model was then used to provide the most comprehensive design charts yet created for hydraulic ram pump, and was also used in the investigation of operational limits for the device. The study represents: the development of the first detailed simulation of the hydraulic ram pump and the most significant insight to date into the detail of operation of a hydraulic ram pump. The result of the study is the provision of an accurate method of pump calibration, an accurate method of pump performance prediction, and the first comprehensive design charts to be produced for the hydraulic ram pump.
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Wu, Gang. "Adaptive position and force control of hydraulic robots, theory, simulation and experiments." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq23554.pdf.
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Shende, Sachin. "Database-driven hydraulic simulation of canal irrigation networks using object-oriented high-resolution methods." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/14208.
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Canal hydraulic models can be used to understand the hydraulic behaviour of large and complex irrigation networks at low cost. A number of computational hydraulic models were developed and tested in the early 1970s and late 80s. Most were developed using finite difference schemes and procedural programming languages. In spite of the importance of these models, little progress was made on improving the numerical algorithms behind them. Software development efforts were focused more on developing the user interface rather than the core algorithm. This research develops a database-driven, object-oriented hydraulic simulation model for canal irrigation networks using modern high-resolution shock capturing techniques that are capable of handling variety of flow situations which includes trans-critical flow, shock propagation, flows through gated structures and channel networks. The technology platforms were carefully selected by taking into account a multi-user support and possible migration of the new software to a web-based one which integrates a Java-based object-oriented model with a relational database management system that is used to store network configuration and simulation parameters. The developed software is tested using a benchmark test suite formulated jointly by the Department for Environment, Food and Rural Affairs (DEFRA) and the Environment Agency (EA). A total of eight tests (seven of them adapted from the DEFRAjEA benchmark suite) were run and results compiled. The developed software has outperformed ISIS, REC-RAS and MIKE 11 in three of the benchmark tests and equally well for the other four. The outcome of this research is therefore a new category in hydraulic simulation software that uses modern shock-capturing methods fully integrated with a configurational relational database that has been fully evaluated and tested.
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Svensson, Oskar. "Electrohydraulic Power Steering Simulation : Dynamic, thermal and hydraulic modelling." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-265674.
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There are several benets of electrohydraulic power steering systems, as compared to hydraulicpower steering systems where the pump is driven directly by the engine of the vehicle. Someof these benets are increased eciency and improved steering performance. The purpose ofthis project is to create a simulation model of the electrohydraulic power steering system inSimulink, excluding the hydraulic circuit. The model should thus consist of the electric motor,the drive electronics, the control system, the hydraulic pump as well as the communication andinterface to the master simulation system in which the model will be used.As a start a mathematical model of the motor is derived. Then the motor controller includingtwo current controllers and a speed controller is developed. The switching signals for the threephase bridge that drives the motor are calculated using space vector modulation. The motordrives a hydraulic pump, which is modeled using data sheet eciency curves. Finally a thermalmodel of the drive is developed. To fulll real time requirements, a lumped parameter approachis chosen. The nal model is exported as a Functional Mock-up Unit, which is a black-boxencapsulation of the complete simulation model.The simulation model is compared to measurement data to conrm its validity. Thesecomparisons shows that the dynamic response of the motor and its controller are close to themeasured values and that the thermal model adequately corresponds to the thermal tests. Thehydraulic pump model varied from measurements more than the other sub-modules. It was,however, seen as acceptable. Overall the system response was satisfactory, but naturally a lotof future improvements and new features could be made to improve the model.Det finns flera fördelar med elektrohydraulisk servostyrning, där hydraulpumpen drivs av en el-motor, jämfört med hydraulisk servostyrning, där pumpen drivs direkt av fordonets förbränningsmotor. Några av dessa fördelar är ökad effektivitet och förbättrad styrprestanda. Syftet med detta projekt är att skapa en Simulink-modell av ett elektrohydraulisk system för servostyrning, exklusive hydraulkretsen. Modellen ska alltså bestå av delmodeller för elmotorn, drivelektroniken, styrsystemet, hydraulpumpen samt kommunikation med den övergripande simuleringsplattformen.Inledningsvis beskrivs en matematisk modell av elmotorn och efter det utvecklas motorstyrningen, bestående av två strömregulatorer samt en hastighetsregulator. Spänningen från strömregulatorerna uppnås genom space vector-modulation, som beräknar de pulskvoter som krävs för att uppnå denna spänning. Elmotorn driver en pump. Denna pump modelleras med hjälp av data från pumpens datablad. Slutligen modelleras drivelektronikens termiska egenskaper med ett termiskt nätverk. Den slutliga modellen omsluts av en Functional Mock-up Unit somintegreras i den övergripande simuleringsplattformen.
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Chen, Qing [Verfasser]. "Numerical investigation of internal flow in hydraulic valves and dynamic interactions in hydraulic systems with CFD and simplified simulation methods / Qing Chen." Aachen : Shaker, 2005. http://d-nb.info/1181607736/34.
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Olsson, Markus. "Simulation Comparison of Auto-Tuning Methods for PID Control." Thesis, Linköping University, Department of Electrical Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11106.
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Auto-tuning has become an important function in distributed control systems (DCS) and is especially appreciated in large industries that can have hundreds of controllers. In the DCS 800xA manufactured by ABB, there is an auto-tuning method implemented based on a relay experiment to determine the ultimate gain and the ultimate period, with which the PID parameters are obtained using the modified Ziegler-Nichols tuning rules. The tuning procedure can then proceed with a step identification experiment to get additional parameters for kappa-tau tuning. In the previous DCS, called Advant, there was another auto-tuning approach implemented. This method was based on dominant pole design, which included an identification of the process. The purpose of this thesis is to compare these auto-tuning methods, to investigate if the dominant pole placement method should be migrated to the 800xA system.
Automatisk trimning har blivit en viktig funktion i distribuerade styrsystem (DCS och är speciellt av intresse för stora industrier som kan ha flera hundra regulatorer. Den automatiska trimningen som idag är implementerad i ABB:s DCS 800xA är baserad på ett reläexperiment för att bestämma den ultimata förstärkningen och den ultimata periodtiden. Modifierade Ziegler-Nichols trimningsregler används sedan för att bestämma PID parametrarna. Vidare kan trimningen fortsätta med ett stegsvars-experiment för att erhålla ytterliggare parametrar och trimma med kappa-tau metoden. Den automatiska trimningsmetoden som var implementerad i tidigare DCS, Advant, var baserad på dominant polplacering med identifiering av processen. Syftet med detta examensarbete är att jämföra dessa automatiska trimningsmetoder för att undersöka om den tidigare trimningsmetoden baserad på dominant polplacering ska implementeras i 800xA systemet.
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Rask, Amanda. "Indirect methods as quality control of cemented hydraulic fill : Renström mine, Boliden mineral AB." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-72962.
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The Renström mine, Boliden Mineral AB, uses, among other methods, the Transverse long hole stoping method with backfill. The mine uses a cement-stabilized hydraulic fill (CHF), which is a mixture of enrichment sand, cement and water. The most important factor in relation to strength is the water cement ratio. Today, only tests have been performed on the surface and in laboratory tests. The purpose of this work is thus to study the possibility of using other types of methods that can give a better understanding of the strength of the entire filling volume. Studies on backfill containing Portland cement and sulphur have shown that the UCS strength decreases with time, which can cause problems for the mine. A leaching method (MRM leaching test) used to evaluate potential sulphide soils has been used in this study on the backfill to investigate the sulphurs impact on the cement mixture. Electrical conductivity, pH, and redox potential were investigated and gave similar results, where the higher cement levels (8%, 10%, and 12%) were indistinguishable while the lower cement content (4%) differed significantly from the other levels. This probably indicates that the higher cement levels have a greater resistance to the influence of the sulphur. The most promising results were given when the method was used on enrichment sand alone. The linear lowering of the pH value of the enrichment sand, from pH 4.9 to about pH 3, point to that the enrichment sand contains large amounts of sulphur, as previously chemical analysis has shown. This suggests that the method can best be used in an early stage before the sand is mixed with cement. The strength results on the samples showed a strength after 7 days that was in line with the 90-day strength. However, all 90 day samples had decreased in strength during the time sequence, which may be an effect of the sulphur content, but should be further investigated to be determined. The smaller size of the samples was also experienced as a challenge during the temperature measurements due to small temperature variations and environmental effects. A maturity method for predicting the strength of concrete called "The maturity method" has been investigated in this study. To determine the strength maturity relationship, both the temperature related to time and the equivalent age must be evaluated. The study showed that the method cannot be used on the mine's backfill without first making adjustments related to the lower cement content used in the backfill compared with concrete constructions, since it is not possible to determine the strength growth in the early stage as the method requires.
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Pirgul, Khalid, and Jonathan Svensson. "Verification of Powertrain Simulation Models Using Machine Learning Methods." Thesis, Linköpings universitet, Fordonssystem, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166290.
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This thesis is providing an insight into the verification of a quasi-static simulation model based on the estimation of fuel consumption using machine learning methods. Traditional verification using real test data is not always available. Therefore, a methodology consisting of verification analysis based on estimation methods was developed together with an improving process of a quasi-static simulation model. The modelling of the simulation model mainly consists of designing and implementing a gear selection strategy together with the gearbox itself for a dual clutch transmission dedicated to hybrid application. The purpose of the simulation model is to replicate the fuel consumption behaviour of vehicle data provided from performed tests. To verify the simulation results, a so-called ranking model is developed. The ranking model estimates a fuel consumption reference for each time step of the WLTC homologation drive cycle using multiple linear regression. The results of the simulation model are verified, and a scoring system is used to indicate the performance of the simulation model, based on the correlation between estimated- and simulated data of the fuel consumption. The results show that multiple linear regression can be an appropriate approach to use as verification of simulation models. The normalised cross-correlation power is also examined and turns out to be a useful measure for correlation be-tween signals including a lag. The developed ranking model is a fast first step of evaluating a new vehicle configuration concept.
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Reichenwallner, Christopher, and Daniel Wasborg. "Control of a Hydraulic Hybrid System for Wheel Loaders." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-158902.
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In recent years many companies have investigated the use of hybrid technology due to the potential of increasing the driveline’s efficiency and thus reducing fuel consumption. Previous studies show that hydraulic hybrid technology can be favourable to use in construction machinery such as wheel loaders, which often operate in repetitive drive cycles and have high transient power demands. Parallel as well as Series hybrid configurations are both found suitable for wheel loader applications as the hybrid configurations can decrease the dependency on the torque converter. This project has investigated a novel hydraulic hybrid concept which utilizes the wheel loaders auxiliary pump as a supplement to enable both Series and Parallel hybrid operation. Impact of accumulator sizes has also been investigated, for which smaller accumulator sizes resembles a hydrostatic transmission. The hybrid concept has been evaluated by developing a wheel loader simulation model and a control system based on a rule-based energy management strategy. Simulation results indicate improved energy efficiency of up to 18.80 % for the Combined hybrid. Moreover, the accumulator sizes prove to have less impact on the energy efficiency. A hybrid system with decreased accumulator sizes shows improved energy efficiency of up to 16.40 %.
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Wondimu, Nahom Abebe. "SIMULATED AND EXPERIMENTAL SLIDING MODE CONTROL OF A HYDRAULIC POSITIONING SYSTEM." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1145419922.
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Moradi, Mohammed Hasan. "New modelling and control methods with application to combined cycle power plants." Thesis, University of Strathclyde, 2002. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21157.
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This thesis reports the analysis and modelling required to build a software simulation of combine cycle power plants. A new MIMO PID controller tuning method and a novel predictive PID controller design method for MIMO systems are also described in the thesis. The emphasis of this work is on simulation; identification and controller design methods. The thesis begins with an account of the combined cycle power plant modelling and simulation development. This culminates in a library of different blocks and subsystems of combined cycle power plants. The simulation development shows how the steady state and dynamic behaviour of combined cycle power plants can be simulated and implemented in the SMULINK and MATLAB environment using per unit models, which are suitable for control design. In the identification stage, the relay identification method is used to identify the critical points of the system for a newly defined criterion at bandwidth frequency. Then, the identified critical points are used to tune PID controllers. The thesis then outlines multivariable PID tuning methods and makes a comparison between these methods and the new relay identification method concerning their robustness for MIMO systems. The last two chapter of thesis are concerned with a new predictive PID controller design method for both SISO and MIMO systems. This methodology is concerned with the design of PID controllers, which have similar features to the model-based predictive controller. Generalized Predictive Control (GPC) design principles are used to develop the PID control with predictive capabilities for both SISO and MIMO systems. The combined cycle power plant simulation, especially the boiler subsystem, is used as an example throughout the thesis.
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Yilmaz, Metin. "Control Of Groundwater By Underground Dams." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1259621/index.pdf.
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In this study underground dams are briefly described and detailed information about the design and construction aspects is provided. Since the material, of which dam wall is composed, is the main variable influencing the groundwater behavior, various types of dam wall are discussed. The use and usefulness of the underground dams as a means of sustainable development, and their performance in the management of groundwater resources are analyzed with the help of two example studies. In the first example a hypothetical idealized aquifer is considered, while in the second one, a real aquifer is selected.
For the performance evaluation, and for the analysis of the impact of the underground dams on the groundwater behavior, numerical simulation is opted. For that purpose, a well-known computer code, MODFLOW, A Modular Three-Dimensional Finite Difference Groundwater Flow Model of U.S. Geological Survey, (McDonald and Harbaugh, 1988) is used.
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Preece, Adam. "An investigation into methods to aid the simulation of turbulent separation control." Thesis, University of Warwick, 2008. http://wrap.warwick.ac.uk/94093/.
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The reduction of drag on commercial aircraft is an active field of study especially with environmental pressures to reduce the carbon emissions associated with climate change. To this end, the AEROMEMS-II project was commissioned by the EU with a view to investigate methods for reducing drag by using MEMS devices for controlling separation. One method for investigating flow control devices is to use the field of Computational Fluid Dynamics (CFD) to simulate the flow interactions produced in flow control applications and assess their effect. Simulating such flows can be computationally expensive so a number of methods have been investigated here to assess their use in flow control simulation applications. The first of these is the Immersed Boundary Method (IBM) which allows complex geometries to be simulated using simple cartesian grid CFD codes. IBMs are found to reduce requirements whilst maintaining flow resolution and accuracy. Next is the use of turbulence modelling with wall functions to reduce the need for fine grids near any solid surfaces. This method is found to work well and can allow the grid spacing near the wall to be 100 times coarser than with no wall functions applied. Finally, Detached Eddy Simulation (DES) has been considered as a method for allowing unsteady flow control structures to be simulated without being damped by conventional turbulence modelling. Each of these methods is presented, implemented and validated against known flow cases to assess their abilities fully. All three methods have then been applied together to a known experimental turbulent flow-control set-up at the University of Lille (fellow partners in the AEROMEMS-II project) in order to assess the feasibility of using all of these methods together to simulate flow control. All three of these methods are seen to work well together although not always with the same effect.
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龐維宗 and Wai-chung Pong. "Interstage stock control for series production lines with variable operation times." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31207054.
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Boukheddimi, Melya. "Human gait simulation using motion generation methods from robotics." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30105.
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Le corps humain est un système complexe composé de plus de 600 muscles, qui contribuent à l'actionnement de plus de 200 degrés de liberté (DDL) [35]. Il s'agit donc d'un système hautement redondant pour la plupart des tâches. De nombreux auteurs ont suggéré que le système nerveux central ne contrôle pas indépendamment en temps réel chaque muscle et DDL [54]. Bien que le nombre élevé de muscles et de DDL rende difficile le problème du contrôle moteur, il offre de grandes capacités d'adaptation au corps pour l'exécution de plusieurs tâches simultanément si nécessaire [54]. Parmi ces tâches qui requièrent un haut niveau de coordination motrice, la marche bipède est cruciale. La marche bipède est le moyen naturel de locomotion de l'être humain. Bien que ce mouvement soit assez stéréotypé entre les individus, on ne sait toujours pas comment le système nerveux central coordonne-t-il le système musculo-squelettique complexe afin de générer la marche, ni comment les différentes séquences du cycle de la marche sont régulées. Afin de répondre à ces problématiques, nous avons proposé de simuler la démarche semblable à celle de l'être- humain en utilisant un modèle simplifié de corps rigides poly-articulés (modèle squelettique 3D du corps entier comprenant 42 degrés de liberté), sur lequel nous avons appliqué deux méthodes différentes de génération de mouvement. Cette thèse s'inscrit donc dans le cadre de la génération de la démarche humaine, en utilisant des méthodes de génération de mouvement issues de la robotique. La première contribution de cette thèse, montre qu'il suffit de contrôler un petit nombre de tâches soigneusement sélectionnées pour reproduire fidèlement la cinématique de la démarche humaine. Pour cela, un contrôleur de tâches Hiérarchiques est appliqué au modèle du corps complet en utilisant uniquement 3 tâches hiérarchiques afin de générer neuf différentes allures de type humain. L'analyse des allures simulées montre l'émergence de propriétés significatives de la marche humaine. Afin de valider nos résultats, une comparaison entre les rotations articulaires des mouvements simulés et des mouvements de référence humaine est effectuée. Enfin, une discussion est fournie pour illustrer l'intérêt de l'approche choisie en comparaison à des travaux connexes. La deuxième contribution de cette thèse est basée sur l'hypothèse bien connue stipulant que le mouvement humain est le résultat d'un processus d'optimisation. Nous considérons ici un ensemble réduit de critères, qui semblent être optimisés pendant la marche humaine, issues de l'observation de la marche humaine et de l'état de l'art correspondant. Le Contrôle Optimal direct basé sur l'algorithme de Programmation Dynamique Différentielle est appliqué sur ces critères avec le modèle corps complet afin de générer neuf mouvements de marche différents. Les mouvements de marche simulés sont ensuite analysés et comparés à la référence humaine pour démontrer la qualité de la méthode de génération de la marche sélectionnée. L'intérêt de cette approche d'optimisation pour la génération de mouvements de type humain est enfin discuté. Finalement, une comparaison entre les deux méthodes issues de la robotique est présentée et discutée, en impliquant une analyse de la qualité des mouvements obtenusThe human body is a complex system made of more than 600 muscles, which contribute to the actuation of more than 200 Degrees of Freedom (DoFs) [35]. It is therefore a highly redundant system for most kinematic tasks. Many authors have suggested that the central nervous system does not independently control in real-time each muscle and DoFs [54]. Though the high number of muscles and DoFs makes motor control problems difficult, it offers high adaptation capabilities to the body for executing multiple tasks simultaneously when necessary [54]. Among the tasks that require a high level of motor coordination, bipedal gait is a crucial one. The bipedal gait is the natural means of human locomotion. Despite the fact that this movement is quite stereotyped across individuals, it is still unclear how the central nervous system coordinates the complex musculo-skeletal system for gait generation, and how the different sequences of the gait cycle are regulated. In order to address these issues, we proposed to simulate the human-like gait using a simplified model of poly- articulated rigid bodies (3D whole-body skeletal model including 42 degrees of freedom), on which we applied two different motion generation methods. Hence, this thesis is part of the human-like gait generation problem, using motion generation methods from robotics. The first contribution shows that controlling only a small set of adequately selected tasks is sufficient to closely reproduce the human gait kinematics. To this aim, a Hierarchical task controller is applied to the whole-body model with only 3 hierarchical tasks, to generate nine different human-like gaits. The analysis of the simulated gaits shows the emergence of significant human-like properties in walking. In order to validate our results, a comparison between the simulated and human reference joint rotations is conducted. In the end, a discussion is given to illustrate the interest of this approach comparing to related works.The second contribution is based on the well-known hypothesis that human motion is the result of an optimization process. We consider a reduced set of criteria, which seem to be optimized during the human gait, taken from the observation of human walking and the study of the related literature. Direct Optimal Control based on the Differential Dynamic Programming algorithm is applied following these criteria with the whole-body model to generate nine different walking motions. The simulated walking motions are then analyzed and compared to the human reference to show the quality of the gait generation process. The interest of this optimization approach for human-like motion generation is finally discussed. Finally, a comparison between the two methods from robotics is presented and discussed, involving an analysis of the obtained movements' quality
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Sharnez, Rizwan 1960. "Dynamic simulation and control of crystal-size distribution in a continuous crystallizer." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/558079.
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Shimizu, Juri, Takuya Otani, Kenji Hashimoto, and Atsuo Takanishi. "Simulation of an interlocking hydraulic direct-drive system for a biped walking robot." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71091.
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Biped robots with serial links driven by an electric motor experience problems because the motor and transmission are installed in each joint, causing the legs to become very heavy. Previous solutions involved robots using servo valves, a type of highly responsive proportional valve. However, high supply pressure is necessary to realize high responsiveness and the resulting energy losses are large. To address this problem, we proposed a hydraulic direct-drive system in which the pump controls the cylinder meter-in flow, while a proportional valve controls the meter-out flow. Furthermore, our hydraulic interlocking drive system connects two hydraulic direct-drive systems for biped humanoid robots and concentrates the pump output on one side cylinder. The meter-in flow rate of the other side cylinder is controlled by the meter-out flow rate of the cylinder on which the pump is concentrated. A comparison of the walking simulation performance with that of the conventional independent system shows that our proposed system reduces the motor output power by 24.3%. These results prove the feasibility of constructing a two-legged robot without having to incorporate highly responsive servo valves.
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Petry, Matthias, Olivier Reinertz, and Hubertus Murrenhoff. "Development of a Simulation Model of a Self-Energizing Hydraulic Brake to Actively Compensate Brake Torque Oscillations." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-199896.
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Friction force oscillations caused by changing properties of the contact zone between brake disc and pad are well known from various applications. Resulting effects like brake judder are known phenomena in brake technologies and in the scope of various scientific work. A new measure to potentially reduce brake torque oscillations is the active compensation with the use of the control system of a self-energizing hydraulic brake (SEHB). New in comparison to traditional disc brakes is the fact that the brake torque is measured by the pressure in an additional supporting cylinder. Thus, the brake system is able to work in brake torque control mode. Within this paper a dynamic simulation model of the SEHB is shown and evaluated with measurement data achieved from a full scale test rig for railway applications. Based on the simulation model a pressure control strategy is developed to minimize brake torque oscillations of lower frequencies. The control parameters of the simulation are transferred to the experimental setup. Finally, simulation and experimental results are compared. Future work will deal with the development of control strategies to additionally minimize brake torque oscillations of the higher dynamics.
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Joy, Dawn, and Karthik Sekaran. "Electronic Pump Control and Benchmarking of Simulation Tools : AMESim and GT Suite." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69567.
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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.
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Ramamurthi, Vikram. "Analysis of production control methods for semiconductor research and development fabs using simulation /." Link to online version, 2004. https://ritdml.rit.edu/dspace/handle/1850/938.
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Heng, Jeremy. "On the use of transport and optimal control methods for Monte Carlo simulation." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:6cbc7690-ac54-4a6a-b235-57fa62e5b2fc.
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This thesis explores ideas from transport theory and optimal control to develop novel Monte Carlo methods to perform efficient statistical computation. The first project considers the problem of constructing a transport map between two given probability measures. In the Bayesian formalism, this approach is natural when one introduces a curve of probability measures connecting the prior to posterior by tempering the likelihood function. The main idea is to move samples from the prior using an ordinary differential equation (ODE), constructed by solving the Liouville partial differential equation (PDE) which governs the time evolution of measures along the curve. In this work, we first study the regularity solutions of Liouville equation should satisfy to guarantee validity of this construction. We place an emphasis on understanding these issues as it explains the difficulties associated with solutions that have been previously reported. After ensuring that the flow transport problem is well-defined, we give a constructive solution. However, this result is only formal as the representation is given in terms of integrals which are intractable. For computational tractability, we proposed a novel approximation of the PDE which yields an ODE whose drift depends on the full conditional distributions of the intermediate distributions. Even when the ODE is time-discretized and the full conditional distributions are approximated numerically, the resulting distribution of mapped samples can be evaluated and used as a proposal within Markov chain Monte Carlo and sequential Monte Carlo (SMC) schemes. We then illustrate experimentally that the resulting algorithm can outperform state-of-the-art SMC methods at a fixed computational complexity. The second project aims to exploit ideas from optimal control to design more efficient SMC methods. The key idea is to control the proposal distribution induced by a time-discretized Langevin dynamics so as to minimize the Kullback-Leibler divergence of the extended target distribution from the proposal. The optimal value functions of the resulting optimal control problem can then be approximated using algorithms developed in the approximate dynamic programming (ADP) literature. We introduce a novel iterative scheme to perform ADP, provide a theoretical analysis of the proposed algorithm and demonstrate that the latter can provide significant gains over state-of-the-art methods at a fixed computational complexity.
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Fang, Fang. "A simulation study for Bayesian hierarchical model selection methods." View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-2/fangf/fangfang.pdf.
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Sheldon, Karl Edward. "Analysis Methods to Control Performance Variability and Costs in Turbine Engine Manufacturing." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32290.
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Few aircraft engine manufacturers are able to consistently achieve high levels of performance reliability in newly manufactured engines. Much of the variation in performance reliability is due to the combined effect of tolerances of key engine components, including tip clearances of rotating components and flow areas in turbine nozzles. This research presents system analysis methods for determining the maximum possible tolerances of these key components that will allow a turbine engine to pass a number of specified performance constraints at a selected level of reliability.
Through the combined use of a state-of-the-art engine performance code, component clearance loss models, and stochastic simulations, regions of feasible design space can be explored that allow for a pre-determined level of engine reliability. As expected, constraints such as spool speed and fuel consumption that are highly sensitive to certain component tolerances can significantly limit the feasible design space of the component in question. Discussed are methods for determining the bounds of any components feasible design space and for selecting the most economical combinations of component tolerances.
Unique to this research is the method that determines the tolerances of engine components as a system while maintaining the geometric constraints of individual components. The methods presented in this work allow for any number of component tolerances to be varied or held fixed while providing solutions that satisfy all performance criteria. The algorithms presented in this research also allow for an individual specification of reliability on any number of performance parameters and geometric constraints.
This work also serves as a foundation for an even larger algorithm that can include stochastic simulations and reliability prediction of an engine over its entire life cycle. By incorporating information such as time dependent performance data, known mission profiles, and the influence of maintenance into the component models, it would be possible to predict the reliability of an engine over time. Ultimately, a time-variant simulation such as this could help predict the timing and levels of maintenance that will maximize the life of an engine for a minimum cost.Master of Science
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Pei, Dekun. "Development of simulation tools, control strategies, and a hybrid vehicle prototype." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45904.
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This thesis (1) reports the development of simulation tools and control strategies for optimizing hybrid electric vehicle (HEV) energy management, and (2) reports the design and testing of a hydraulic hybrid school bus (HHB) prototype. A hybrid vehicle is one that combines two or more energy sources for use in vehicle propulsion. Hybrid electric vehicles have become popular in the consumer market due to their greatly improved fuel economy over conventional vehicles. The control strategy of an HEV has a paramount effect on its fuel economy performance. In this thesis, backward-looking and forward-looking simulations of three HEV architectures (parallel, power-split and 2-mode power-split) are developed. The Equivalent Cost Minimization Strategy (ECMS), which weights electrical power as an equivalent fuel usage, is then studied in great detail and improvements are suggested. Specifically, the robustness of an ECMS controller is improved by linking the equivalence factor to dynamic programming and then further tailoring its functional form. High-fidelity vehicle simulations over multiple drive-cycles are performed to measure the improved performance of the new ECMS controller, and to show its potential for online application.
While HEVs are prominent in the consumer market and studied extensively in current literature, hydraulic hybrid vehicles (HHVs) only exist as heavy utility vehicle prototypes. The second half of this thesis reports design, construction, and testing of a hydraulic hybrid school bus prototype. Design considerations, simulation results, and preliminary testing results are reported, which indicate the strong potential for hydraulic hybrids to improve fuel economy in the school bus vehicle segment.
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Liu, Yi. "Numerical simulations of the aerodynamic characteristics of circulation control wing sections." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/12051.
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Galoppo, Nico Lin Ming C. "Animation, simulation, and control of soft characters using layered representations and simplified physics-based methods." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2008. http://dc.lib.unc.edu/u?/etd,2051.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2008.Title from electronic title page (viewed Feb. 17, 2009). "...in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Computer Science." Discipline: Computer Science; Department/School: Computer Science.
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McConnell, David James. "Analysis of model referenced adaptive control applied to robotic devices." Thesis, Kansas State University, 1985. http://hdl.handle.net/2097/17099.
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Ingvarsson, Gustaf. "Assessment of a Thermal De-Icing Solution and Control Methods using Simulations." Thesis, KTH, Maskinkonstruktion (Avd.), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-244391.
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Lastbilar körandes i nordiska vinterförhållanden riskerar att strålkastare, och andra lyktor blir täckta utav is. Detta hindrar ljuset från att skina på vägen, något som måste åtgärdas manuellt utav föraren. Tidigare har problemet varit löst genom den extra värme som strålas från glödlamporna i lyktorna men i och med övergången till LED har detta problem vuxit. Strålkastarna är nu i behov av en lösning som kan ta bort, samt förhindra att ny, snö och is från linserna. Detta examensarbete, som utfördes på Scania CV, Södertälje, undersöker kontrollmetoder för en termisk avisnings lösning. Projektets huvuduppgift har varit att utveckla och använda en simuleringsmodell för avisnings processen. Modellen används sedan för att jämföra två stycken kontrollmetoder för avisningen och för att förhindra att ny is bildas. För att hitta en lämplig termisk avisningslösning undersöktes de tre alternativen för värmetransport i material. En potentiell lösning för varje alternativ jämfördes sedan med varandra. Den bästa lösning var den som använder värmeledning i form utav värmeslingor i linsen. Denna lösning låter värmaren vara nära isen och använder sig av den effektivaste transportalternativet. Värmaren inkluderas i simuleringsmodellen om beskriver värmetransporten i en lins täckt med is. Två kontrollmetoder valdes sedan baserat på en litteraturstudie inom området. Studien resulterade i två hybrid controllers, en som använder sig utav gain-scheduling och en andra som använder sig utav en smith-prediktor. Både metoder implementerades i simuleringsmodellen och deras prestanda jämfördes. Hybrid controllern med smith-prediktorn fanns vara den metod som presterade bäst, då den var både snabbare samt hade mindre översläng. Metoden visade sig dock vara känsligare mot störningar på återkopplingen. Kontrollmetoden med smith prediktorn är den som rekommenderas för användning i vidare arbete med den avisnings lösning. Ett första steg innan implementering med hårdvara föreslås vara jobb på ett filter för återkopplingen.t has been discovered that trucks driving in Nordic winter conditions run the risk of the headlights, and other lights, getting covered in ice and snow. This prevents the lights from illuminating he roads. It has previously been solved by excess heat from the light bulbs, with the recent change to LED lights this problem has escalated. The headlights are now in need of a de-icing system capable of removing ice and snow, as well as preventing it from building up on the lenses. This thesis project carried out at Scania CV, Södertälje, deals with the controlling method for a thermal de-icing solution. The main task of the project was the development and use of simulation model for a chosen heater solution. On this model two developed control methods were compared. In order to find a suitable thermal solution, the three different modes of heat transport were investigated and a solution for each mode was compared against each other. The best solution found was resistance wires molded into the lens, this due to being near the ice and having the most efficient mode of transfer. This solution was incorporated into a simulation model, that described the heat transfer process of a lens covered in ice. Two control methods were chosen based of a literature research, a hybrid controller using gain scheduling and a second hybrid controller using a smith predictor. These were implemented into the simulation model and their performance compared. The smith predictor had the better performance out of the two, being generally faster and has less overshoot. The method does have problems with feedback disturbances, requiring filters in real life implementations. The control method using smith prediction is the one recommended for future work on this project. Before implementation on hardware work needs to be done regarding filtering.
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Ohenoja, M. (Markku). "Computational methods for exploiting image-based data in paper web profile control." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526212821.
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Abstract Sheet and film forming processes such as paper manufacturing pose a challenging monitoring and control problem, where quality variations are classified into machine direction (MD), cross-machine direction (CD) and residual variation. The measurements are typically collected with a scanning sensor that covers only a small part of the paper web, and therefore provides a very limited view of the paper web, setting performance limitations on the online monitoring and control. The development of cameras, light sources and computation hardware enable the consideration of utilizing in-use web inspection systems in paper machines to measure the paper web variations with a considerably higher resolution, sampling rate and coverage. The light transmittance images captured with this kind of system need, however, to be converted into a controllable quality property, such as basis weight, in order to utilize the new measurement information for control purposes. In this thesis, computational methods are identified and developed that are capable of combining light transmittance and scanning measurements, and can efficiently utilize the combined information for control purposes. The possible benefits gained with these image-based measurements in paper machine online monitoring and profile control are evaluated in a simulation environment. In a real paper machine, the benefits are ultimately dependent on the machine configuration and the nature of paper variations therein. It was found that with a suitable estimation method, light transmittance could increase the awareness of basis weight variations such as fast MD variation, tilted waves and dynamic CD variation patterns, which are practically undetectable using scanner-based measurement. The enhanced basis weight estimation enables a considerable improvement in the dynamic performance of profile controls. CD control was able to handle fast variations earlier classified as uncontrollable residual variation. In MD control, enhanced estimation enabled the development of a control strategy that led to improved reference tracking and disturbance rejection propertiesTiivistelmä Paperinvalmistus on yksi esimerkki levyjen tai kalvojen valmistusprosesseista, jotka ovat tyypillisesti haasteellisia prosessin monitoroinnin ja säädön kannalta. Laatuvaihtelut näissä prosesseissa luokitellaan koneensuuntaisiin (MD), poikkisuuntaisiin (CD) ja jäännösvaihteluihin. Paperikoneella mittaukset kerätään tavallisesti radan yli liikkuvalla skannaavalla sensorilla, joka tarjoaa vain hyvin rajoitetun määrän informaatiota paperiradasta, asettaen siten rajoituksia online monitoroinnin ja säädön suorituskyvylle. Kameroiden ja valonlähteiden kehitys sekä laskentakapasiteetin kasvu mahdollistavat paperiradan vaihteluiden mittaamisen huomattavasti korkeammalla resoluutiolla ja näytteenottovälillä jo käytössä olevilla vianilmaisujärjestelmillä. Vianilmaisujärjestelmän keräämä valon transmittanssitieto pitää kuitenkin muuntaa esimerkiksi neliömassatiedoksi, jotta uutta mittausinformaatiota voitaisiin hyödyntää myös prosessin online säädössä nykyisillä toimilaitteilla. Tässä työssä on identifioitu ja kehitetty laskennallisia menetelmiä, jotka kykenevät yhdistämään kuvantavan ja skannaavan mittauksen sekä käyttämään tätä yhdistettyä tietoa säätötarkoituksissa. Kuvapohjaisen mittauksen mahdollisia hyötyjä online monitoroinnissa ja profiilien säädössä on arvioitu simulointiympäristössä. Saavutettavat hyödyt paperikoneella ovat lopulta riippuvaisia myös koneen konfiguraatiosta ja koneella ilmenevien laatuvaihteluiden luonteesta. Tulokset osoittavat, että transmittanssimittauksen ja tehokkaan estimointimenetelmän avulla kyetään lisäämään tietämystä neliömassamuutoksista, joita ei käytännössä voida havaita pelkän skannaavan mittauksen avulla. Estimoinnin parempi suorituskyky mahdollistaa myös profiilisäätöjen dynaamisen suorituskyvyn kasvattamisen. CD-säätö voitiin laajentaa kattamaan myös nopeita vaihteluita, jotka ovat aiemmin luokiteltu jäännösvaihteluksi. MD-säädölle voitiin kehittää säätöstrategia, jonka avulla sekä asetusarvojen seurantaa että häiriöiden vaimennusta pystyttiin parantamaan
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Li, Pengfei. "Stochastic Methods for Dilemma Zone Protection at Signalized Intersections." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/28805.
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Dilemma zone (DZ), also called decision zone in other literature, is an area where drivers face an indecisiveness of stopping or crossing at the yellow onset. The DZ issue is a major reason for the crashes at high-speed signalized intersections. As a result, how to prevent approaching vehicles from being caught in the DZ is a widely concerning issue. In this dissertation, the author addressed several DZ-associated issues, including the new stochastic safety measure, namely dilemma hazard, that indicates the vehiclesâ changing unsafe levels when they are approaching intersections, the optimal advance detector configurations for the multi-detector green extension systems, the new dilemma zone protection algorithm based on the Markov process, and the simulation-based optimization of traffic signal systems with the retrospective approximation concept. The findings include: the dilemma hazard reaches the maximum when a vehicle moves in the dilemma zone and it can be calculated according the caught vehiclesâ time to the intersection; the new (optimized) GES design can significantly improve the safety, but slightly improve the efficiency; the Markov process can be used in the dilemma zone protection, and the Markov-process-based dilemma zone protection system can outperform the prevailing dilemma zone protection system, the detection-control system (D-CS). When the data collection has higher fidelity, the new system will have an even better performance. The retrospective approximation technique can identify the sufficient, but not excessive, simulation efforts to model the true system and the new optimization algorithm can converge fast, as well as accommodate the requirements by the RA technique.Ph. D.
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Rosin, Korinna [Verfasser]. "Adaptive Finite Element Methods for Contact Problems embedded in a Fictitious Domain - Simulation and Optimal Control / Korinna Rosin." München : Verlag Dr. Hut, 2019. http://d-nb.info/1202168701/34.
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N'guessan, Marc-Arthur. "Space adaptive methods with error control based on adaptive multiresolution for the simulation of low-Mach reactive flows." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC017.
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Ce travail vise au développement de nouvelles méthodes numériques adaptatives pour la simulation numérique de phénomènes physiques multi-échelles en temps et en espace. Nous nous concentrons sur les écoulements réactifs à faible nombre de Mach, caractéristiques d'un grand nombre de configurations industrielles telles que la convection naturelle, la dynamique de fronts de flamme ou encore les décharges plasmas. La raideur associée à ce type de problèmes, que ce soit via le terme source chimique qui présente un large spectre d'échelles de temps caractéristiques ou encore via la présence de forts gradients très localisés associés aux fronts de réaction, génère des difficultés numériques considérables. Il est donc nécessaire de concevoir des méthodes sur mesure pour traiter la raideur de telles applications, afin d'obtenir des résultats d'une grande précision avec un coût calcul raisonnable. Dans ce cadre général, nous introduisons de nouvelles méthodes numériques pour la résolution des équations de Navier-Stokes incompressibles, une étape importante dans la réalisation d'un solveur hydrodynamique pour les écoulements à faible nombre de Mach. Nous construisons un solveur volumes finis avec adaptation de maillage par l'analyse de multirésolution, qui permet un contrôle a priori des erreurs générées par l'adaptation de maillage. Pour ce faire, nous développons un nouveau schéma de volumes finis collocalisé, avec un traitement original des modes de pression et de vitesse parasites qui n'affecte pas la précision de la discrétisation spatiale. Cette dernière est couplée à un nouveau schéma de Runge-Kutta additif d'ordre 3 pour les écoulements incompressibles, qui présente des propriétés de stabilité adaptées à la raideur des équations différentielles algébriques semi-explicites d'index 2. L'ensemble de cette stratégie est implémentée dans le code de calcul scientifique mrpy. Ce dernier est écrit en Python, et repose sur la librairie PETSc, écrite en C, pour le traitement des opérations d'algèbre linéaire. Nous évaluons l'efficacité algorithmique de cette stratégie par la simulation numérique d'un transport de scalaire passif dans un écoulement incompressible sur maillage adaptatif. Ce travail présente donc un nouveau solveur hydrodynamique d'ordre élevé pour les écoulements incompressibles, avec adaptation de maillage par multirésolution et contrôle d'erreur, qui peut être étendu aux écoulements à faible nombre de MachWe address the development of new numerical methods for the efficient resolution of stiff Partial Differential Equations modelling multi-scale time/space physical phenomena. We are more specifically interested in low Mach reacting flow processes, that cover various real-world applications such as flame dynamics at low gas velocity, buoyant jet flows or plasma/flow interactions. It is well-known that the numerical simulation of these problems is a highly difficult task, due to the large spectrum of spatial and time scales caused by the presence of nonlinear The adaptive spatial discretization is coupled to a new 3rd-order additive Runge-Kutta method for the incompressible Navier-Stokes equations, combining a 3rd-order, A-stable, stiffly accurate, 4-stage ESDIRK method for the algebraic linear part of these equations, and a 4th-order explicit Runge-Kutta scheme for the nonlinear convective part. This numerical strategy is implemented from scratch in the in-house numerical code mrpy. This software is written in Python, and relies on the PETSc library, written in C, for linear algebra operations. We assess the capabilities of this mechanisms taking place into dynamic fronts. In this general context, this work introduces dedicated numerical tools for the resolution of the incompressible Navier-Stokes equations, an important first step when designing an hydrodynamic solver for low Mach flows. We build a space adaptive numerical scheme to solve incompressible flows in a finite-volume context, that relies on multiresolution analysis with error control. To this end, we introduce a new collocated finite-volume method on adaptive rectangular grids, with an original treatment of the spurious pressure and velocity modes that does not alter the precision of the discretization technique. new hydrodynamic solver in terms of speed and efficiency, in the context of scalar transport on adaptive grids. Hence, this study presents a new high-order hydrodynamics solver for incompressible flows, with grid adaptation by multiresolution, that can be extended to the more general low-Mach flow configuration
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Tan, Sean. "Development of a dynamic model of a ventricular assist device for investigation of control systems." Ottawa, 1996.
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Yang, Ruochen. "Diagnosis of Evaporative Emissions Control System Using Physics-based and Machine Learning Methods." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587651390226087.
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Blume, Martin [Verfasser]. "3D Flow Simulation for the Investigation of Cavitation and Its Relationship To Erosion, Turbulence and Primary Breakup in Hydraulic Components by Single-Fluid Multi-Phase Methods / Martin Blume." Düren : Shaker, 2021. http://d-nb.info/1238497381/34.
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Persson, Oskar, and Samuel Svensson. "Exploring methods for dependency management in multi-repositories : Design science research at Saab Training and simulation." Thesis, Jönköping University, JTH, Avdelningen för datavetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-54102.
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Dependency problems for developers are like sneezing for people with pollen allergies during the spring, an everyday problem. This is especially true when working in multi-repositories. The dependency problems that occur do so as a byproduct of enabling developers to work on different components of a project in smaller teams, where everything is version controlled.Nearly all developers use version control systems, such as Git, Mercurial, or Subversion. While version control systems have helped developers for nearly 40 years and are constantly getting updated, there are still functionalities that do not exist. One example of that is having a good way of managing dependencies and allowing developers to download projects without having to handle dependency problems manually. The solutions that version control systems offer to help manage dependencies (e.g., Git’s submodules or Mercurial’s subrepositories), do not enable developers a fail-safe download or build the project if it contains dependency problems.In this study, a case study was conducted at Saab Training and Simulation to explore methods for dependency management as well as discuss and highlight some of the problems that emerge when working with dependencies in multi-repositories.An argument can be made that the functionality of dependency management systems, both package managers and version control systems’ solutions are not up to date on how dependencies are used in the development, during this time.In this paper, a novel approach to dependency management is introduced with the possibility to describe the dependencies dynamically by providing the utility to describes usages of a repository (such as simulation of hardware or the main project). As well as discussing the necessary functionalities that are required to handle such a system.By re-opening the dialog about dependency management as well as describing problems that arise in such environments, the goal is to inspire further research within these areas.
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Yang, Xiaojing. "A study on simulation-based and human factors-centered design methods for advanced main control rooms in nuclear power plants." Kyoto University, 2005. http://hdl.handle.net/2433/144435.
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Svensson, Bo. "Optimisation of Manufacturing Systems Using Time Synchronised Simulation." Licentiate thesis, University West, University West, Department of Engineering Science, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-2481.
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Capaci, Francesca. "Contributions to the Use of Statistical Methods for Improving Continuous Production." Licentiate thesis, Luleå tekniska universitet, Industriell Ekonomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-66256.
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Complexity of production processes, high computing capabilities, and massive datasets characterize today’s manufacturing environments, such as those of continuous andbatch production industries. Continuous production has spread gradually acrossdifferent industries, covering a significant part of today’s production. Commonconsumer goods such as food, drugs, and cosmetics, and industrial goods such as iron,chemicals, oil, and ore come from continuous processes. To stay competitive intoday’s market requires constant process improvements in terms of both effectivenessand efficiency. Statistical process control (SPC) and design of experiments (DoE)techniques can play an important role in this improvement strategy. SPC attempts toreduce process variation by eliminating assignable causes, while DoE is used toimprove products and processes by systematic experimentation and analysis. However,special issues emerge when applying these methods in continuous process settings.Highly automated and computerized processes provide an exorbitant amount ofserially dependent and cross-correlated data, which may be difficult to analyzesimultaneously. Time series data, transition times, and closed-loop operation areexamples of additional challenges that the analyst faces.The overall objective of this thesis is to contribute to using of statisticalmethods, namely SPC and DoE methods, to improve continuous production.Specifically, this research serves two aims: [1] to explore, identify, and outlinepotential challenges when applying SPC and DoE in continuous processes, and [2] topropose simulation tools and new or adapted methods to overcome the identifiedchallenges.The results are summarized in three appended papers. Through a literaturereview, Paper A outlines SPC and DoE implementation challenges for managers,researchers, and practitioners. For example, problems due to process transitions, themultivariate nature of data, serial correlation, and the presence of engineering processcontrol (EPC) are discussed. Paper B further explores one of the DoE challengesidentified in Paper A. Specifically, Paper B describes issues and potential strategieswhen designing and analyzing experiments in processes operating under closed-loopcontrol. Two simulated examples in the Tennessee Eastman (TE) process simulatorshow the benefits of using DoE techniques to improve and optimize such industrialprocesses. Finally, Paper C provides guidelines, using flow charts, on how to use thecontinuous process simulator, “The revised TE process simulator,” run with adecentralized control strategy as a test bed for developing SPC and DoE methods incontinuous processes. Simulated SPC and DoE examples are also discussed.
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Arvidsson, Emil. "Future Nordic Grid Frequency Quality : A quantitative simulation study of current and potential frequency control methods with emphasis on synthetic inertia." Thesis, Uppsala universitet, Elektricitetslära, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-447871.
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The power grid faces stability problems due to loss of inertia. The ancillary services balancing the system must be improved to maintain stability. In contrast to earlier studies, this thesis estimates how the future grid frequency quality in both the short and long term is affected by different control methods, using an ensemble of quality measures. The thesis uses conventional one-area models for the power grid and FCR-N (frequency containment reserve – normal operation) but develops new models for FCR-D (– disturbed operation), FFR (fast frequency reserve), and synthetic inertia (SI). To acquire proper input data the thesis uses an inverse model of the power grid to compute the momentary load disturbance, i.e., the difference between load and generation, from the grid frequency. The thesis makes a difference between proportional and derivative SI, where the latter is the one commonly associated with the term SI. The results show that derivative SI can improve some quality measures but requires very high power capacity. In contrast, proportional SI improves almost every measure the most, for a fraction of the required capacity. Derivative SI is therefore worth less from a system perspective. However, it is shown that the quality measures improved by derivative SI are related to hydropower wear and tear, making it more interesting for hydro power owners. Moreover, FFR gives no benefit to long time quality measures. Considering the short-term analysis where a large disturbance occurs, FFR gives almost no benefit and risks worsening the stability. Also, for the large disturbance, proportional SI performs the best. The results are limited by the small number of simulations that were performed and can only provide indications of trends. A more solid conclusion, however, is that one cannot expect transmission system operators (TSO) to introduce an ancillary service that builds on derivative SI.
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Scullin, Michelle E. "Integrating Value Stream Mapping and Simulation." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd898.pdf.
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Rao, Sachit Srinivasa. "Sliding mode control in mechanical, electrical and thermal distributed processes." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1164817694.
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Aranda, Saldaña Edwin Antonio 1974. "Metodologia eficiente para análise de redes complexas de abastecimento de água." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257965.
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Orientador: Paulo VatavukTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-25T09:08:31Z (GMT). No. of bitstreams: 1 ArandaSaldana_EdwinAntonio_D.pdf: 3905557 bytes, checksum: d00eb707af3e32709401a2fbbcc42709 (MD5) Previous issue date: 2014
Resumo: Este trabalho apresenta o desenvolvimento de um modelo computacional, baseado no Método da Teoria Linear Modificado (MTLM) proposto por WOOD (1981) e a implementação do algoritmo do Gradiente proposto por TODINI e PILATI (1988). Além disso, apresentam-se comparações entre ambos para a análise de redes de abastecimento de água de grande porte. De acordo com a proposta deste trabalho, para criar um modelo baseado no MTLM tornou-se indispensável a definição prévia de um algoritmo para a seleção automática de circuitos. Para essa finalidade, adotou-se o algoritmo de Breadth First Search (BFS), baseado na teoria dos grafos e utilizado satisfatoriamente na seleção automática dos circuitos nas redes hidráulicas. A formulação adotada na implementação dos modelos estabelece as equações de continuidade nos nós e as equações de conservação de carga nas malhas em termos da vazão para cada elemento do sistema, apresentando um conjunto de equações não lineares que relacionam vazão com perda de carga. Uma vez linearizado o sistema de equações, o uso da biblioteca numérica de programação e otimização (KLU) na resolução de sistemas lineares mostrou-se eficiente para ambos os métodos analisados neste trabalho. A validade e a consistência dos resultados fornecidos pelo modelo proposto foram confirmadas através de sua comparação com o software Epanet 2.0. Os resultados obtidos através de simulações com a finalidade de comparar os resultados obtidos pelo MTLM e pelo método que utiliza o algoritmo do gradiente mostraram a eficiência de processamento e do tempo computacional de ambos os métodos. As comparações foram feitas utilizando redes de até 1000 tubos, fornecendo resultados inéditos, pois os trabalhos encontrados, conforme a revisão bibliográfica, utilizaram redes pequenas com número de tubos em torno de 10% do tamanho das redes estudadas neste trabalho
Abstract: This thesis presents for the first time the development of two computational models, one model is based on the Modified linear theory method (MTLM) that was initially proposed by WOOD in 1981 and the other model is based on the implementation of the Gradient algorithm that was early proposed by TODINI and PILATI in 1987. In addition, this thesis presents comparisons between both methods for the analysis of large pipe networks. In order to develop a model based on the MTLM method was first necessary to define an algorithm for the automatic selection of circuits. For this reason, the algorithm of Breadth First Search (BFS) was used which is based on the theory of graphs. This algorithm was successfully used for the automatic selection of circuits in hydraulic pipe networks. The methods adopted for the implementation of these models used continuity equations in the junctions as well as equations of conservation of energy in the loops in terms of flow for each element of the system that resulted in a set of non-linear equations, relating flow with head lose. Once the systems of equations were linearized, the use of the KLU library for the solution of linear systems showed promising results for both methods investigated in this thesis. The validity and consistency of the results obtained herein by the proposed models were also confirmed through comparisons with results obtained by the software Epanet version 2.0. The results obtained through simulations with the goal to compare with results obtained in this thesis with the MTLM method and the method that uses a gradient algorithm showed satisfactory results with an efficient processing and computational time by both methods. The comparisons were performed with up to 1000 tubes, gathering new and robust data when compared to available literature that used only a small network with a number of tubes of less than 10%
Doutorado
Recursos Hidricos, Energeticos e Ambientais
Doutor em Engenharia Civil
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Curtis, J. Jeffrey. "Mixed structural models for decision making under uncertainty using stochastic system simulation and experimental economic methods : application to information security control choice." Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/80444/.
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This research is concerned with whether and to what extent information security managers may be biased in their evaluation of and decision making over the quantifiable risks posed by information management systems where the circumstances may be characterized by uncertainty in both the risk inputs (e.g. system threat and vulnerability factors) and outcomes (actual efficacy of the selected security controls and the resulting system performance and associated business impacts). Although ‘quantified security’ and any associated risk management remains problematic from both a theoretical and empirical perspective (Anderson 2001; Verendel 2009; Appari 2010), professional practitioners in the field of information security continue to advocate the consideration of quantitative models for risk analysis and management wherever possible because those models permit a reliable economic determination of optimal operational control decisions (Littlewood, Brocklehurst et al. 1993; Nicol, Sanders et al. 2004; Anderson and Moore 2006; Beautement, Coles et al. 2009; Anderson 2010; Beresnevichiene, Pym et al. 2010; Wolter and Reinecke 2010; Li, Parker et al. 2011) The main contribution of this thesis is to bring current quantitative economic methods and experimental choice models to the field of information security risk management to examine the potential for biased decision making by security practitioners, under conditions where information may be relatively objective or subjective and to demonstrate the potential for informing decision makers about these biases when making control decisions in a security context. No single quantitative security approach appears to have formally incorporated three key features of the security risk management problem addressed in this research: 1) the inherently stochastic nature of the information system inputs and outputs which contribute directly to decisional uncertainty (Conrad 2005; Wang, Chaudhury et al. 2008; Winkelvos, Rudolph et al. 2011); 2) the endogenous estimation of a decision maker’s risk attitude using models which otherwise typically assume risk neutrality or an inherent degree of risk aversion (Danielsson 2002; Harrison, Johnson et al. 2003); and 3) the application of structural modelling which allows for the possible combination and weighting between multiple latent models of choice (Harrison and Rutström 2009). The identification, decomposition and tractability of these decisional factors is of crucial importance to understanding the economic trade-offs inherent in security control choice under conditions of both risk and uncertainty, particularly where established psychological decisional biases such as ambiguity aversion (Ellsberg 1961) or loss aversion (Kahneman and Tversky 1984) may be assumed to be endemic to, if not magnified by, the institutional setting in which these decisions take place. Minimally, risk averse managers may simply be overspending on controls, overcompensating for anticipated losses that do not actually occur with the frequency or impact they imagine. On the other hand, risk-seeking managers, where they may exist (practitioners call them ‘cowboys’ – they are a familiar player in equally risky financial markets) may be simply gambling against ultimately losing odds, putting the entire firm at risk of potentially catastrophic security losses. Identifying and correcting for these scenarios would seem to be increasingly important for now universally networked business computing infrastructures. From a research design perspective, the field of behavioural economics has made significant and recent contributions to the empirical evaluation of psychological theories of decision making under uncertainty (Andersen, Harrison et al. 2007) and provides salient examples of lab experiments which can be used to elicit and isolate a range of latent decision-making behaviours for choice under risk and uncertainty within relatively controlled conditions versus those which might be obtainable in the field (Harrison and Rutström 2008). My research builds on recent work in the domain of information security control choice by 1) undertaking a series of lab experiments incorporating a stochastic model of a simulated information management system at risk which supports the generation of observational data derived from a range of security control choice decisions under both risk and uncertainty (Baldwin, Beres et al. 2011); and 2) modeling the resulting decisional biases using structural models of choice under risk and uncertainty (ElGamal and Grether 1995; Harrison and Rutström 2009; Keane 2010). The research contribution consists of the novel integration of a model of stochastic system risk and domain relevant structural utility modeling using a mixed model specification for estimation of the latent decision making behaviour. It is anticipated that the research results can be applied to the real world problem of ‘tuning’ quantitative information security risk management models to the decisional biases and characteristics of the decision maker (Abdellaoui and Munier 1998).
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Watts, Krista L. "Modeling the use of the AJCN in a tactical environment." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Jun%5FWatts.pdf.
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