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Mehmood, Adeel. "Modeling, simulation and robust control of an electro-pneumatic actuator for a variable geometry turbocharger." Phd thesis, Université de Technologie de Belfort-Montbeliard, 2012. http://tel.archives-ouvertes.fr/tel-00827445.
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The choice of technology for automotive actuators is driven by the need of high power to size ratio. In general, electro-pneumatic actuators are preferred for application around the engine as they are compact, powerful and require simple controlling devices. Specially, Variable Geometry Turbochargers (VGTs) are almost always controlled with electro-pneumatic actuators. This is a challenging application because the VGT is an important part of the engine air path and the latter is responsible for intake and exhaust air quality and exhaust emissions control. With government regulations on vehicle pollutant emissions getting stringent by the year, VGT control requirements have also increased. These regulations and requirements can only be fulfilled with precise dynamic control of the VGT through its actuator. The demands on actuator control include robustness against uncertainty in operating conditions, fast and smooth positioning without vibration, limited number of measurements. Added constraints such as nonlinear dynamic behavior of the actuator, friction and varying aerodynamic forces in the VGT render classical control methods ineffective. These are the main problems that form the core of this thesis.In this work, we have addressed the above mentioned problems, using model based control complemented with robust control methods to overcome operational uncertainties and parametric variations. In the first step, a detailed physical model of an electro-pneumatic actuator has been developed; taking into account the nonlinear characteristics originating from air compressibility and friction. Means to compensate for aerodynamic force have been studied and implemented in the next step. These include model parametric adaptation and one dimensional CFD (Computational Fluid Dynamics) modeling. The complete model has been experimentally validated and a sensitivity analysis has been conducted to identify the parameters which have the greatest impact upon the actuator's behavior. The detailed simulation model has then been simplified to make it suitable for control purposes while keeping its essential behavioral characteristics (i.e. transients and dynamics). Next, robust controllers have been developed around the model for the control objective of accurate actuator positioning in presence of operational uncertainty. An important constraint in commercial actuators is that they provide output feedback only, as they are only equipped with low-cost position sensors. This hurdle has been overcome by introducing observers in the control loop, which estimate other system states from the output feedback. The estimation and control algorithms have been validated in simulation and experimentally on diesel engine test benches.
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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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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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Papoutsidakis, Michail G. "Modern methods for position control of systems : real-world and simulated application to a time variant pneumatic actuator." Thesis, University of the West of England, Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501091.
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The Ph.D. programme arose naturally from the fundamental questions remaining after completing MPhil research at UWR in a very similar subject area. which was in achieving effective proportional position control of a linear pneumatic actuator. There are many challenging reasons for using pneumatic systems for control in certain important potential application areas, i.e., their numerous and multiple applications in modern industry due to their extensive beneficial characteristics. The still-unsolved problem of robust long-term proportional control of pneumatic actuators keeps the continuous research interest of engineers high. It is believed that when the operation time increases, so does the temperature inside the cylinder body.Any increase in temperature affects the system performance. For example, one effect is that the piston rubber expands and the contact area becomes greater; hence the frictional forces are affected. The rubber seal, which is between the piston and the cylinder body, also deforms according to air pressure increase. These long-term effects were the major cause of the problems that existed during all of the author's MPhil experimentation, using any kind of control method; the result was that frequent retuning of the controller could not be avoided.
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Chen, Yang. "Modeling, Control, and Design Study of Balanced Pneumatic Suspension for Improved Roll Stability in Heavy Trucks." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/95168.
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This research investigates a novel arrangement to pneumatic suspensions that are commonly used in heavy trucks, toward providing a dynamically balanced system that resists body roll and provides added roll stability to the vehicle. The new suspension, referred to as "balanced suspension," is implemented by retrofitting a conventional pneumatic suspension with two leveling valves and a symmetric plumbing arrangement to provide a balanced airflow and air pressure in the airsprings. This new design contributes to a balanced force distribution among the axles, which enables the suspension to maintain the body in a leveled position both statically and dynamically. This is in contrast to conventional heavy truck pneumatic suspensions that are mainly adjusted quasi-statically to level the body in response to load variations. The main objectives of the research are to discover and analyze the effects of various pneumatic components on the suspension dynamic response and numerically study the benefits of the pneumatically balanced suspension system. A pneumatic suspension model is established to capture the details of airsprings, leveling valves, check valves, pipes, and air tank based on the laws of fluid mechanics and thermodynamics. Experiments are designed and conducted to help determine and verify the modeling parameters and components. Co-simulation technique is applied to establish a multi-domain model that couples highly non-linear fluid dynamics of the pneumatic suspension with complex multi-body dynamics of an articulated vehicle. The model is used to extensively study effects of pneumatic balanced control of the suspensions on the tractor and trailer combination dynamics. The simulations indicate that the dual leveling valve arrangement of the balanced suspension provides better adjustments to the body roll by charging the airsprings on the jounce side, while purging air from the rebound side. Such an adjustment allows maintaining a larger difference in suspension force from side to side, which resists the vehicle sway and levels the truck body during cornering. Additionally, the balanced suspension better equalizes the front and rear drive axle air pressures, for a better dynamic load sharing and pitch control. It is evident from the simulation results that the balanced suspension increases roll stiffness without affecting vertical stiffness, and thereby it can serve as an anti-roll bar that results in a more stable body roll during steering maneuvers. Moreover, the Failure Mode and Effects Analysis (FMEA) study suggests that when one side of the balanced suspension fails, the other side acts to compensate for the failure. On the other hand, if the trailer is also equipped with dual leveling valves, such an arrangement will bring an additional stabilizing effect to the vehicle in case of the tractor suspension failure. The overall research results presented show that significant improvements on vehicle roll dynamics and suspension dynamic responsiveness can be achieved from the balanced suspension system.PHD
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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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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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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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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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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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Ashby, Ryan Michael. "Hardware in the Loop Simulation of a Heavy Truck Braking System and Vehicle Control System Design." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366046155.
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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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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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de, Ruyter Adam, and mikewood@deakin edu au. "Towards development of a quality cost model for automotive stamping." Deakin University. School of Engineering and Technology, 2002. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20060803.123754.
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The current work used discrete event simulation techniques to model the economics of quality within an actual automotive stamping plant. Automotive stamping is a complex, capital intensive process requiring part-specific tooling and specialised machinery. Quality control and quality improvement is difficult in the stamping environment due to the general lack of process understanding and the large number to interacting variables. These factors have prevented the widespread use of statistical process control.
In this work, a model of the quality control techniques used at the Ford Geelong Stamping plant is developed and indirectly validated against results from production. To date, most discrete event models are of systems where the quality control process is clearly defined by the rules of statistical process control. However, the quality control technique used within the stamping plant is for the operator to perform a 100% visual inspection while unloading the finished panels. In the developed model, control is enacted after a cumulative count of defective items is observed, thereby approximating the operator who allows a number of defective panels to accumulate before resetting the line. Analysis of this model found that the cost sensitivity to inspection error is dependent upon the level of control and that the level of control determines line utilisation. Additional analysis of this model demonstrated that additional inspection processes would lead to more stable cost structures but these structures many not necessarily be lower cost.
The model was subsequently applied to investigate the economics of quality improvement. The quality problem of panel blemishes, induced by slivers (small metal fragments), was chosen as a case stuffy. Errors of 20-30% were observed during direct validation of the cost model and it was concluded that the use of discrete event simulation models for applications requiring high accuracy would not be possible unless the production system was of low complexity. However, the model could be used to evaluate the sensitivity of input factors and investigating the effects of a number of potential improvement opportunities.
Therefore, the research concluded that it is possible to use discrete event simulation to determine the quality economics of an actual stamping plant. However, limitations imposed by inability of the model to consider a number of external factors, such as continuous improvement, operator working conditions or wear and the lack of reliable quality data, result in low cost accuracy. Despite this, it still can be demonstrated that discrete event simulation has significant benefits over the alternate modelling methods.
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Sarper, H{u00FC}seyin. "Cellular and functional production environments: design methodology and comparison." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/81025.
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A hybrid methodology was developed to fairly compare functional and cellular production environments with respect to the production of machined parts which constitute the indivisible components of some final products. The methodology provides a means of designing each production environment at the lowest possible cost and then comparing the two environments with respect to cost and non-cost performance measures. The results show that the long-held belief that the cellular manufacturing or group technology method of production may be superior to that of the traditional functional or job shop layout may not be correct. A detailed comparison using four problem sets with different job and machine mixes failed to indicate a clear case in which the cellular environment performed better than the functional.
The methodology consists of two stages. Stage one has six hierarchical steps which systematically determine machine requirements and layout planning of each environment through mathematical modelling. External and internal operation constraints and inputs such as stochastic daily demand and operation times were considered. Stochastic programming was used in handling uncertain daily demand and operation times by specifying a desired minimum probability of meeting the demand for each job type in both environments. The MPSIII package was used in solving large mixed integer problems that resulted once nonlinear terms, due to the chance-constrained nature of the segments of the models, were linearized. Because of the large problem sizes, MPSIII input files had to be created using FORTRAN codes.
In stage two, the SIMAN simulation language was used to determine the feasibility of stage one decisions and to obtain other system information. In simulation, some approximations were made to implement stage one decisions. For example, jobs received an average processing time in each operation class area rather than the exact operation time of the specific machine type to which the jobs were assigned in stage one. The effect of material handling distances and the use of limited number of work-in-process carriers were considered. Although the methodology was mainly developed for the comparison of the two production environments, it is readily usable for individual design of either production environment.
In addition to the two main stages of development, this research also required the development of two other procedures: unitizing daily demands and the modifying the previously available job/cell grouping methods.Ph. D.
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O'Connor, Robert Gerard Verfasser], Martin A. [Akademischer Betreuer] [Grepl, Benjamin [Akademischer Betreuer] Stamm, and Stefan [Akademischer Betreuer] Volkwein. "Reduced basis methods for the analysis, simulation, and control of noncoercive parabolic systems / Robert Gerard O'Connor ; Martin Alexander Grepl, Benjamin Stamm, Stefan Volkwein." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/119406650X/34.
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O'Connor, Robert [Verfasser], Martin A. [Akademischer Betreuer] Grepl, Benjamin [Akademischer Betreuer] Stamm, and Stefan [Akademischer Betreuer] Volkwein. "Reduced basis methods for the analysis, simulation, and control of noncoercive parabolic systems / Robert Gerard O'Connor ; Martin Alexander Grepl, Benjamin Stamm, Stefan Volkwein." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/119406650X/34.
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Propes, Nicholas Chung. "Hybrid Systems Diagnosis and Control Reconfiguration for Manufacturing Systems." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5150.
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A methodology for representing and analyzing manufacturing systems in a hybrid systems framework for control reconfiguration purposes in the presence of defects and failures at the product and system levels is presented. At the top level, a supervisory Petri net directs parts/jobs through the manufacturing system. An object-based hybrid systems model that incorporates both Petri nets at the event-driven level and differential equations at the time-driven level describes the subsystems. Rerouting capabilities utilizing this model at the product and operation levels were explained. Simulations were performed on a testbed model for optimal time and mode transition cost to determine the route for parts. The product level reconfiguration architecture utilizes an adaptive network-based fuzzy inference system (ANFIS) to map histogram comparison metrics to set-point adjustments when product defects were detected. Tests were performed on good and defective plastic parts from a plastic injection molding machine. In addition, a mode identification architecture was described that incorporates both time- and event-driven information to determine the operating mode of a system from measured sensor signals. Simulated data representing the measured process signals from a Navy ship chiller system were used to verify that the appropriate operating modes were detected.
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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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Yilmaz, Tansu. "Acoustical Analysis Of A Multipurpose Hall By Computer Simulation Method: Metu Northern Cyprus Campus Auditorium (ncca) As A Case Study." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605957/index.pdf.
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In this study, impulse response of a multipurpose hall, namely METU Northern Cyprus Campus Auditorium (NCCA) is analyzed and the acoustical quality of the auditorium is evaluated. Suggestions to increase the acoustical satisfaction has been made and to overcome the probability of bass-rise caused by the noise of HVAC systems, a proposal has been made to control low frequency sounds by introducing the volume resonators for the specified frequency. For the study, Odeon, which is used effectively in computer based acoustical simulation studies, is used for the analysis part. In the analysis, a 3D drawing of the hall has been produced by the help of the exact dimensions derived from the original submission of the project by the permission of the authorities.
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Fiorella, C. L. "Text versus verbal real-time feedback during simulation-based training of higher-order cognitive skills." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4659.
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A crucial component of instructional design for simulation-based training systems involves optimizing the presentation of complex material in order to maximize knowledge acquisition and application. One approach toward facilitating the learning of this complex information is to instantiate instructional strategies within the training systems themselves. However, there are few established guidelines in place which are meant specifically for real-time guidance strategies within simulation-based environments. Consequently, this study aims to apply findings from the literature on instructional information presentation to drive decisions for how to most effectively provide real-time feedback during training of simulated decision-making tasks. Research has shown that presenting text information in an auditory mode during direct instruction of operational tasks enhances learning and reduces the probability of learners experiencing cognitive overload. Similar effects have been found regarding the presentation modality of feedback during operational tasks. In the current study, this principle was extended by comparing text versus verbal real-time feedback presentation during learning of higher-level cognitive skills in a virtual environment. Participants were instructed on how to perform a simulated decision-making task, while receiving text, verbal or no instructional feedback in real-time, based on their performance. Participants then completed an assessment scenario in which no feedback was provided to any group. It was hypothesized that a linear relationship would exist across each of the three conditions, with the verbal group making the best decisions, followed by the text group, and then by the control group. Additionally, reduced cognitive load was expected throughout the instructional process for those receiving verbal feedback prompts compared to those receiving text prompts and the control.; Analyses revealed several significant linear trends across conditions regarding measures of knowledge acquisition and application. The results provide support for the hypothesis that verbal real-time feedback is more effective than text during training of primarily visual tasks for the acquisition of higher-order cognitive skills such as decision making. There were no significant linear trends regarding the amount of cognitive load subjectively reported during training and assessment. The results of this study indicate that instructional systems intended to train primarily visual tasks should present real-time feedback in verbal rather than text form.ID: 029050250; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2010.; Includes bibliographical references (p. 57-64).
M.S.
Masters
Engineering
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Poncet, Philippe. "Méthodes particulaires pour la simulation des sillages tridimensionnels." Phd thesis, Université Joseph Fourier (Grenoble), 2001. http://tel.archives-ouvertes.fr/tel-00004699.
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Ce travail est consacré au développement des méthodes particulaires pour la résolution des équations de Navier-Stokes incompressibles en dimension 3. L'évaluation des formules de Biot-Savart ayant un coût de calcul prohibitif en dimension trois, on utilise un couplage grille-particules. On applique alors cette technique à la simulation et au contrôle de sillages produits par un cylindre. La première partie est consacrée à la méthode numérique proprement dite. On commence par présenter le modèle lagrangien et la méthode utilisée pour calculer le champ de vitesse, qui est la clef de voûte du schéma. On décrit ensuite, au chapitre 2 comment sont calculées les couches limites. Enfin, on présente au chapitre 3 l'algorithme à pas fractionnaire utilisé, ainsi que les méthodes de transfert entre jeux de particules et grilles sous-jacentes, et le calcul de la diffusion. Le code est alors validé par des simulations d'anneaux tourbillonnaires qui se propulsent sur un obstacle cylindrique, pour des nombres de Reynolds modérés (entre 400 et 2000).La seconde partie utilise la méthode numérique décrite précédemment, en l'appliquant dans un premier temps à la simulation des sillages turbulents qui se développent derrière un cylindre circulaire (chapitre 4), puis au contrôle de ces écoulements au chapitre 4.Il est connu que les solutions bidimensionnelles sont instables pour des nombres de Reynolds suffisamment élevés. Les instabilités tridimensionnelles sont identifiée grâce à leur profil spectral. Elles ont un effet important sur les forces de traînée et sur la fréquence propre de l'écoulement.Le chapitre 5, relatif au contrôle, se propose de mettre en évidence plusieurs phénomènes. On considère un contrôle en boucle ouverte, réalisé par une rotation à pulsation et amplitude constante. On étudie des rotations basse et haute fréquences. Le coefficient de traînée est alors diminué de 43% par le contrôle à haute fréquence, pour un nombre de Reynolds de 550. De plus, on montre que l'écoulement turbulent revient à un état bidimensionnel si l'amplitude de rotation est suffisamment élevée.
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Vikgren, Mattias. "Development and testing of controller that introduces the functionality to lift the second front axle on a heavy vehicle." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-301633.
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The transition to more environmentally sustainable transports, as well as rising fuel prices create a demand for efficient means of transportation. Liftable axles have shown potential to save fuel and reduces tire wear on heavy vehicles. This thesis proposes a simulation environment and a control method for the electronically controlled air suspension system on a four axle truck that enables axle lifting. The goal of the work is to propose a control method that fulfills certain safety criteria and is robust to disturbances introduced by an external un-modeled controller. A simulation environment is proposed, based upon two different physical models of the suspension system. The first model offers simplicity for the initial tuning of the controller and the second model serves as a platform for more realistic testing of the controller before the final vehicle test. The results from the vehicle tests show that the proposed controller is able to regulate the pressure in the suspension bellows to the desired load distribution between the axles of the vehicle, while the vehicle is maintaining a certain height above ground. The vehicle test showed that it was difficult to read the correct pressure in the suspension bellows when the valves controlling the airflow in and out of the suspension bellow were open. A method for compensating the error when the valves are open is proposed.Övergången till hållbara och miljövänliga transporter samt stigande bränslepriser skapar en efterfrågan av mer effektiva transportmedel. Lyftbara axlar har visats medföra minskad bränsleförbrukning och däckslitage. Denna uppsats föreslår en simuleringsmiljö samt en metod för reglering av det elektroniskt styrda luftfjädringssystemet på en fyraxlig lastbil som möjliggör lyftning av en axel. Målet med arbetet är att föreslå en metod för reglering av systemet som uppfyller en rad säkerhetskriterier och är robust för störningar introducerade av en extern, icke-modellerad styrenhet. Den föreslagna simuleringsmiljön är baserad på två olika fysiska modeller av fjädringssystemet. Den första modellen karakteriseras av dess enkelhet och används för inledande testning och justering av regulatorn. Den andra modellen används för mer realistisk testning av regulatorn innan det avslutande fordonstestet. Resultatet från fordonstesterna visar att den föreslagna regulatorn kan reglera trycket i luftbälgen till den önskade lastfördelningen mellan axlarna på fordonet medan dess höjd bibehålls. Under fordonstestet konstaterades att det inte gick att avläsa det korrekta trycket i luftbälgen när ventilerna som styr luftflödet till och från luftbälgen var öppna. En metod för att kompensera felet som uppstår när ventilerna är öppna föreslås.
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Sanchez, Urbina Israel. "Optimizing flow of plastic PBT with 45% glass and mineral fiber reinforcement in an injection over mold process using Taguchi, CPk and mold flow simulation software approaches." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Picinato, Luis Carlos Molina. "Determinação de curvas caracteristicas de unidades produtivas utilizando simulação de sistemas." [s.n.], 1999. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264318.
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Orientador: Oswaldo Luiz AgostinhoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Para enfrentar a crescente competitividade, as atuais empresas ainda executam as suas principais funções de gerenciamento utilizando soluções padrões. Isto ocorre principalmente com relação às atividades de Planejamento e Controle da Produção -PCP. Tais soluções normalmente são insensíveis às relações entre parâmetros operacionais do sistema produtivo, e portanto, não oferecem um suporte adequado aos processos decisórios associados ao PCP. Neste contexto, este traballio, propõe a utilização de Curvas Características em sistemas descentralizados de PCP, subdivididos em Unidades Produtivas. Essas curvas descrevem as relações entre níveis de inventário em processo, tempo de fluxo e nível de utilização do sistema. Para determinar essas relações, foi desenvolvida uma metodologia baseada em técnicas de simulação discreta, que é aplicada em Unidades Produtivas, no caso prático estudado. Os resultados mostram que o processo de determinação das curvas utilizando-se técnicas de simulação é viável, assim como a utilização das curvas podem representar uma importante ferramenta para o controle do fluxo produtivo. Foi também demonstrado que as curvas obtidas podem ser ajustadas em um processo contínuo de mellioriada modelagem do sistema produtivo
Abstract: To face increasing competitive pressures, companies still perform their main management functionsmaking use of standard pattem solutions. This occurs mainlywith regard to the activities of Production Planning and Control - PPC. Such solutions are normallyinsensitiveto the relations among operational parameters of the production system, and consequent1y,do not offer suitable support to the decisive process associated to the PPC. In this sense, this work proposes the use of the "Characteristic Curves" in the decentralized PPC systems (subdivided in Production Units). These curves describe the relations between levels of work in process, flow time and leveI of the system utilization. To establish these relations, a methodology was developed based on discrete simulation techniques, which is applied in Production Units, through a practical case study. The results show that the process of determination of the curves by making use of simulation techniques is viable, as well as that the utilization of the curves can represent an important tool to the control of production flow. It is also shown that the obtained curves can be adjusted in a continuous improvement process ofthe production system modeling
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
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Naber, John F. "The optimization of SPICE modeling parameters utilizing the Taguchi methodology." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/38542.
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A new optimization technique for SPICE modeling parameters has been developed in this dissertation to increase the accuracy of the
circuit simulation. The importance of having accurate circuit simulation models is to prevent the very costly redesign of an
Integrated Circuit (IC). This radically new optimization technique utilizes the Taguchi method to improve the fit between measured and
simulated I-V curves for GaAs MESFETs. The Taguchi method consists of developing a Signal-to-Noise Ratio (SNR) equation that will find the optimum combination of controllable signal levels in a design or process to make it robust or as insensitive to noise as
possible. In this dissertation, the control factors are considered the circuit model curve fitting parameters and the noise is
considered the variation in the simulated I-V curves from the measured I-V curves. This is the first known application of the
Taguchi method to the optimization of IC curve fitting model parameters. In addition, this method is not technology or device dependent and can be applied to silicon devices as well. Improvements in the accuracy of the simulated I-V curve fit reaching 80% has been achieved between DC test extracted parameters and the Taguchi optimized parameters. Moreover, the computer CPU execution time of the optimization process is 96% less than a commercial optimizer utilizing the Levenberg-Marquardt algorithm (optimizing 31 FETs). This technique does a least square fit on the data comparing measured currents versus simulated currents for various combinations of SPICE parameters. The mean and standard deviation of this least squares fit is incorporated in determining the SNR, providing the best combination of parameters within the evaluated range. Furthermore, the optimum values of the parameters are found without additional simulation by fitting the response curves to a quadratic equation and finding the local maximum. This technique can easily be implemented with any simulator that utilizes simulation modeling parameters extracted from measured DC test data. In addition, two methods are evaluated to obtain the worst case modeling parameters. One method lobks at the correlation coefficients between modeling parameters and the second looks at the actual device parameters that define the +/- 30 limits of the process. Lastly, an example is given that describes the applicability of the Taguchi methodology in the design of a differential amplifier, that accounts for the effect of offset voltage.Ph. D.
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Huang, Chien-Chung. "Discrete event system modeling using SysML and model transformation." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45830.
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The objective of this dissertation is to introduce a unified framework for modeling and simulating discrete event logistics systems (DELS) by using a formal language, the System Modeling Language (SysML), for conceptual modeling and a corresponding methodology for translating the conceptual model into a simulation model. There are three parts in this research: plant modeling, control modeling, and simulation generation.
Part 1:Plant Modeling of Discrete Event Logistics Systems.
Contemporary DELS are complex and challenging to design. One challenge is to describe the system in a formal language. We propose a unified framework for modeling DELS using SysML. A SysML subset for plant modeling is identified in this research. We show that any system can be described by using the proposed subset if the system can be modeled using finite state machines or finite state automata. Furthermore, the system modeled by the proposed subset can avoid the state explosion problem, i.e., the number of the system states grows exponentially when the number of the components increases. We also compare this approach to other existing modeling languages.
Part 2:Control Modeling of Discrete Event Logistics Systems.
The development of contemporary manufacturing control systems is an extremely complex process. One approach for modeling control systems uses activity diagrams from SysML, providing a standard object-oriented graphical notation and enhancing reusability. However, SysML activity diagrams do not directly support the kind of analysis needed to verify the control model, such as might be available with a Petri net (PN) model. We show that a control model represented by UML/SysML activity diagrams can be transformed into an equivalent PN, so the analysis capability of PN can be used and the results applied back in the activity diagram model. We define a formal mathematical notation for activity diagrams, show the mapping rules between PN and activity diagrams, and propose a formal transformation algorithm.
Part 3:Discrete Event Simulation Generation.
The challenge of cost-effectively creating discrete event simulation models is well-known. One approach to alleviate this issue is to describe a system using a descriptive modeling language and then transform the system model to a simulation model. Some researchers have tried to realize this idea using a transformation script. However, most of the transformation approaches depend on a domain specific language, so extending the domain specific language may require modifying the transformation script. We propose a transformation approach from SysML to a simulation language. We show that a transformation script can be independent of the associated domain specific language if the domain specific language is implemented as domain libraries using a proposed SysML subset. In this case, both the domain library and the system model can be transformed to a target simulation language. We demonstrate a proof-of-concept example using AnyLogic as the target simulation language.
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Pece, Carlos Alessandro Zanetti. "An engineering vector-like approach to attitude kinematics & nominal attitude state tracking control." Instituto Tecnológico de Aeronáutica, 2002. http://repositorio.utfpr.edu.br/jspui/handle/1/481.
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CAPES, Fundação Casimiro Montenegro FilhoNo tratamento do movimento rotacional tridimensional de corpos rígidos é inevitável lidar-se com o fato de que rotações não são quantidades vetoriais. Elas podem, no entanto, ser tratadas como tais quando o ângulo de rotação é (muito) pequeno. Neste contexto, ou seja, o da análise infinitesimal, as derivadas temporais das variáveis de rotação mantêm um relacionamento simples (às vezes mesmo do tipo vetorial) com os componentes do vetor velocidade angular. Convencionalmente, esta distinta característica não pode ser associada a rotações grandes, nem mesmo medianas. Nesta tese é demonstrado que a relação diferencial entre o vetor rotação e o vetor velocidade angular pode, na realidade, ser expressa em termos de uma simples derivada temporal, desde que o ângulo de rotação seja mantido numa faixa moderada. O artifício permitindo tal simplicidade na equação cinemática (cinemática linear de atitude) com um ângulo de rotação moderado é a escolha criteriosa da base a partir da qual a derivada temporal é observada. Este resultado é utilizado vantajosamente em conjunto com uma versão generalizada das equações de movimento de Euler na construção de uma lei de controle simples. Essa lei realiza, concomitantemente, o rastreamento linear nominal de atitude e o rastreamento linear nominal de velocidade angular (rastreamento linear nominal de estado rotacional), dentro de uma faixa moderada de erro de rastreamento de atitude. O trabalho analítico apresentado é único no sentido em que este combina cinemática rotacional, dinâmica rotacional e controle de forma tal que linearidade nominal entre as variáveis de erro de estado é atingida mesmo para erros moderados de rastreamento de atitude. Pela primeira vez, uma lei de controle permite explicitamente que a dinâmica de erro de estado rotacional em malha fechada seja escolhida e motivada por conceitos físicos úteis da teoria linear de controle. O texto também inclui simulações numéricas que validam e ilustram os resultados teóricos obtidos.
In dealing with rigid body three-dimensional rotational motion, one is inevitably led to face the fact that rotations are not vector quantities. They may, however, be treated as such when the angle of rotation is (very) small. In this context, i.e. the infinitesimal case analysis, the time derivatives of the rotation variables hold simple (sometimes vector-like) relationships to the components of the angular velocity vector. Conventionally, this distinctive characteristic cannot be associated with general moderate-to-large rotations. In this thesis, it is demonstrated that the kinematical differential relationship between the rotation vector and the angular velocity vector may, in fact, be expressed in terms of a mere time derivative, provided that the angle of rotation is kept within moderate bounds. The key to achieve such simplicity in the kinematical equation (linear attitude kinematics) within moderate angles of rotation is a judicious choice of the basis from which the time derivative is observed. This result is used to advantage within a generalised version of Euler’s motion equations to construct a simple control law, which nominally realises both linear attitude tracking and linear angular velocity tracking (nominal linear attitude state tracking), within moderate attitude tracking errors. The analytical work presented here is unique in the sense that it combines attitude kinematics, dynamics and control in such a way that nominal linearity between the attitude state error variables is achieved within moderate attitude tracking errors. For the first time, an attitude control law explicitly enables the nominal closed-loop attitude state error dynamics to be chosen and motivated by useful physical concepts from linear control theory. The text also includes numerical simulations that validate and illustrate the theoretically achieved results.
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MARCHANT, FUENTES Carolina Ivonne. "Essays on multivariate generalized Birnbaum-Saunders methods." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18647.
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CAPES; BOLSA DO CHILE.
In the last decades, univariate Birnbaum-Saunders models have received considerable attention in the literature. These models have been widely studied and applied to fatigue, but they have also been applied to other areas of the knowledge. In such areas, it is often necessary to model several variables simultaneously. If these variables are correlated, individual analyses for each variable can lead to erroneous results. Multivariate regression models are a useful tool of the multivariate analysis, which takes into account the correlation between variables. In addition, diagnostic analysis is an important aspect to be considered in the statistical modeling. Furthermore, multivariate quality control charts are powerful and simple visual tools to determine whether a multivariate process is in control or out of control. A multivariate control chart shows how several variables jointly affect a process. First, we propose, derive and characterize multivariate generalized logarithmic Birnbaum-Saunders distributions. Also, we propose new multivariate generalized Birnbaum-Saunders regression models. We use the method of maximum likelihood estimation to estimate their parameters through the expectation-maximization algorithm. We carry out a simulation study to evaluate the performance of the corresponding estimators based on the Monte Carlo method. We validate the proposed models with a regression analysis of real-world multivariate fatigue data. Second, we conduct a diagnostic analysis for multivariate generalized Birnbaum-Saunders regression models. We consider the Mahalanobis distance as a global influence measure to detect multivariate outliers and use it for evaluating the adequacy of the distributional assumption. Moreover, we consider the local influence method and study how a perturbation may impact on the estimation of model parameters. We implement the obtained results in the R software, which are illustrated with real-world multivariate biomaterials data. Third and finally, we develop a robust methodology based on multivariate quality control charts for generalized Birnbaum-Saunders distributions with the Hotelling statistic. We use the parametric bootstrap method to obtain the distribution of this statistic. A Monte Carlo simulation study is conducted to evaluate the proposed methodology, which reports its performance to provide earlier alerts of out-of-control conditions. An illustration with air quality real-world data of Santiago-Chile is provided. This illustration shows that the proposed methodology can be useful for alerting episodes of extreme air pollution.
Nas últimas décadas, o modelo Birnbaum-Saunders univariado recebeu considerável atenção na literatura. Esse modelo tem sido amplamente estudado e aplicado inicialmente à modelagem de fadiga de materiais. Com o passar dos anos surgiram trabalhos com aplicações em outras áreas do conhecimento. Em muitas das aplicações é necessário modelar diversas variáveis simultaneamente incorporando a correlação entre elas. Os modelos de regressão multivariados são uma ferramenta útil de análise multivariada, que leva em conta a correlação entre as variáveis de resposta. A análise de diagnóstico é um aspecto importante a ser considerado no modelo estatístico e verifica as suposições adotadas como também sua sensibilidade. Além disso, os gráficos de controle de qualidade multivariados são ferramentas visuais eficientes e simples para determinar se um processo multivariado está ou não fora de controle. Este gráfico mostra como diversas variáveis afetam conjuntamente um processo. Primeiro, propomos, derivamos e caracterizamos as distribuições Birnbaum-Saunders generalizadas logarítmicas multivariadas. Em seguida, propomos um modelo de regressão Birnbaum-Saunders generalizado multivariado. Métodos para estimação dos parâmetros do modelo, tal como o método de máxima verossimilhança baseado no algoritmo EM, foram desenvolvidos. Estudos de simulação de Monte Carlo foram realizados para avaliar o desempenho dos estimadores propostos. Segundo, realizamos uma análise de diagnóstico para modelos de regressão Birnbaum-Saunders generalizados multivariados. Consideramos a distância de Mahalanobis como medida de influência global de detecção de outliers multivariados utilizando-a para avaliar a adequacidade do modelo. Além disso, desenvolvemos medidas de diagnósticos baseadas em influência local sob alguns esquemas de perturbações. Implementamos a metodologia apresentada no software R, e ilustramos com dados reais multivariados de biomateriais. Terceiro, e finalmente, desenvolvemos uma metodologia robusta baseada em gráficos de controle de qualidade multivariados para a distribuição Birnbaum-Saunders generalizada usando a estatística de Hotelling. Baseado no método bootstrap paramétrico encontramos aproximações da distribuição desta estatística e obtivemos limites de controle para o gráfico proposto. Realizamos um estudo de simulação de Monte Carlo para avaliar a metodologia proposta indicando seu bom desempenho para fornecer alertas precoces de processos fora de controle. Uma ilustração com dados reais de qualidade do ar de Santiago-Chile é fornecida. Essa ilustração mostra que a metodologia proposta pode ser útil para alertar sobre episódios de poluição extrema do ar, evitando efeitos adversos na saúde humana.