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Pfeiffer, Laurent. "Sensitivity analysis for optimal control problems. Stochastic optimal control with a probability constraint." Palaiseau, Ecole polytechnique, 2013. https://pastel.hal.science/docs/00/88/11/19/PDF/thesePfeiffer.pdf.
Повний текст джерелаАнотація:
Cette thèse est divisée en deux parties. Dans la première partie, nous étudions des problèmes de contrôle optimal déterministes avec contraintes et nous nous intéressons à des questions d'analyse de sensibilité. Le point de vue que nous adoptons est celui de l'optimisation abstraite; les conditions d'optimalité nécessaires et suffisantes du second ordre jouent alors un rôle crucial et sont également étudiées en tant que telles. Dans cette thèse, nous nous intéressons à des solutions fortes. De façon générale, nous employons ce terme générique pour désigner des contrôles localement optimaux pour la norme L1. En renforçant la notion d'optimalité locale utilisée, nous nous attendons à obtenir des résultats plus forts. Deux outils sont utilisés de façon essentielle : une technique de relaxation, qui consiste à utiliser plusieurs contrôles simultanément, ainsi qu'un principe de décomposition, qui est un développement de Taylor au second ordre particulier du lagrangien. Les chapitres 2 et 3 portent sur les conditions d'optimalité nécessaires et suffisantes du second ordre pour des solutions fortes de problèmes avec contraintes pures, mixtes et sur l'état final. Dans le chapitre 4, nous réalisons une analyse de sensibilité pour des problèmes relaxés avec des contraintes sur l'état final. Dans le chapitre 5, nous réalisons une analyse de sensibilité pour un problème de production d'énergie nucléaire. Dans la deuxième partie, nous étudions des problèmes de contrôle optimal stochastique sous contrainte en probabilité. Nous étudions une approche par programmation dynamique, dans laquelle le niveau de probabilité est vu comme une variable d'état supplémentaire. Dans ce cadre, nous montrons que la sensibilité de la fonction valeur par rapport au niveau de probabilité est constante le long des trajectoires optimales. Cette analyse nous permet de développer des méthodes numériques pour des problèmes en temps continu. Ces résultats sont présentés dans le chapitre 6, dans lequel nous étudions également une application à la gestion actif-passifThis thesis is divided into two parts. In the first part, we study constrained deterministic optimal control problems and sensitivity analysis issues, from the point of view of abstract optimization. Second-order necessary and sufficient optimality conditions, which play an important role in sensitivity analysis, are also investigated. In this thesis, we are interested in strong solutions. We use this generic term for locally optimal controls for the L1-norm, roughly speaking. We use two essential tools: a relaxation technique, which consists in using simultaneously several controls, and a decomposition principle, which is a particular second-order Taylor expansion of the Lagrangian. Chapters 2 and 3 deal with second-order necessary and sufficient optimality conditions for strong solutions of problems with pure, mixed, and final-state constraints. In Chapter 4, we perform a sensitivity analysis for strong solutions of relaxed problems with final-state constraints. In Chapter 5, we perform a sensitivity analysis for a problem of nuclear energy production. In the second part of the thesis, we study stochastic optimal control problems with a probability constraint. We study an approach by dynamic programming, in which the level of probability is a supplementary state variable. In this framework, we show that the sensitivity of the value function with respect to the probability level is constant along optimal trajectories. We use this analysis to design numerical schemes for continuous-time problems. These results are presented in Chapter 6, in which we also study an application to asset-liability management
2
Wong, Man-kwun, and 黃文冠. "Some sensitivity results for time-delay optimal control problems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31223655.
Повний текст джерела
3
Scarinci, Teresa. "Sensitivity Relations and Regularity of Solutions of HJB Equations arising in Optimal Control." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066573.
Повний текст джерелаАнотація:
Dans cette thèse nous étudions une classe d’équations de Hamilton-Jacobi-Bellman provenant de la théorie du contrôle optimal des équations différentielles ordinaires. Nous nous intéressons principalement à l’analyse de la sensibilité de la fonction valeur des problèmes de contrôle optimal associés à de telles équations de H-J-B. Dans la littérature, les relations de sensibilité fournissent une “mesure” de la robustesse des stratégies optimales par rapport aux variations de la variable d’état. Ces résultats sont des outils très importants pour le contrôle appliqué, parce qu’ils permettent d’étudier les effets que des approximations des données du système peuvent avoir sur les politiques optimales. Cette thèse est dédiée également à l’étude des problèmes de Mayer et de temps minimal. Nous supposons que la dynamique du problème soit une inclusion différentielle, afin de permettre aux données d’être non régulières et d’embrasser un ensemble plus grand d’applications. Néanmoins, cette tâche rend notre analyse plus difficile. La première contribution de cette étude est une extension de quelques résultats classiques de la théorie de la sensibilité au domaine des problèmes non paramétrées. Ces relations prennent la forme d’inclusions d’état adjoint, figurant dans le principe du maximum de Pontryagin, dans certains gradients généralisés de la fonction valeur évalués le long des trajectoires optimales. En deuxième lieu, nous développons des nouvelles relations de sensibilité impliquant des approximations du deuxième ordre de la fonction valeur. Cette analyse mène à de nouvelles applications concernant la propagation, tant ponctuel que local, de la régularité de la fonction valeur le long des trajectoires optimales. Nous proposons également des applications aux conditions d’optimalitéThis dissertation investigates a class of Hamilton-Jacobi-Bellman equations arising in optimal control of O.D.E.. We mainly focus on the sensitivity analysis of the optimal value function associated with the underlying control problems. In the literature, sensitivity relations provide a measure of the robustness of optimal control strategies with respect to variations of the state variable. This is a central tool in applied control, since it allows to study the effects that approximations of the inputs of the system may produce on the optimal policies. In this thesis, we deal whit problems in the Mayer or in the minimum time form. We assume that the dynamic is described by a differential inclusion, in order to allow data to be nonsmooth and to embrace a large area of concrete applications. Nevertheless, this task makes our analysis more challenging. Our main contribution is twofold. We first extend some classical results on sensitivity analysis to the field of nonparameterized problems. These relations take the form of inclusions of the co-state, featuring in the Pontryagin maximum principle, into suitable gradients of the value function evaluated along optimal trajectories. Furthermore, we develop new second-order sensitivity relations involving suitable second order approximations of the optimal value function. Besides being of intrinsic interest, this analysis leads to new consequences regarding the propagation of both pointwise and local regularity of the optimal value functions along optimal trajectories. As applications, we also provide refined necessary optimality conditions for some class of differential inclusions
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Hannemann-Tamás, Ralf [Verfasser]. "Adjoint Sensitivity Analysis for Optimal Control of Non-Smooth Differential-Algebraic Equations / Ralf Hannemann-Tamás." Aachen : Shaker, 2013. http://d-nb.info/1051575753/34.
Повний текст джерела
5
Park, Sungho. "Development and Applications of Finite Elements in Time Domain." Diss., Virginia Tech, 1996. http://hdl.handle.net/10919/30693.
Повний текст джерелаАнотація:
A bilinear formulation is used for developing the time finite element method (TFM) to obtain transient responses of both linear, nonlinear, damped and undamped systems. Also the formulation, used in the h-, p- and hp-versions, is extended and found to be readily amenable to multi-degree-of-freedom systems. The resulting linear and nonlinear algebraic equations for the transient response are differentiated to obtain the sensitivity of the response with respect to various design parameters. The present developments were tested on a series of linear and nonlinear examples and were found to yield, when compared with other methods, excellent results for both the transient response and its sensitivity to system parameters. Mostly, the results were obtained using the Legendre polynomials as basis functions, though, in some cases other orthogonal polynomials namely, Hermite, Chebyshev, and integrated Legendre polynomials were also employed (but to no great advantage). A key advantage of TFM, and the one often overlooked in its past applications, is the ease in which the sensitivity of the transient response with respect to various design parameters can be obtained. Since a considerable effort is spent in determining the sensitivity of the response with respect to system parameters in many algorithms for parametric identification, an identification procedure based on the TFM is developed and tested for a number of nonlinear single-and two-degree-of-freedom system problems. An advantage of the TFM is the easy calculation of the sensitivity of the transient response with respect to various design parameters, a key requirement for gradient-based parameter identification schemes. The method is simple, since one obtains the sensitivity of the response to system parameters by differentiating the algebraic equations, not original differential equations. These sensitivities are used in Levenberg-Marquardt iterative direct method to identify parameters for nonlinear single- and two-degree-of-freedom systems. The measured response was simulated by integrating the example nonlinear systems using the given values of the system parameters. To study the influence of the measurement noise on parameter identification, random noise is added to the simulated response. The accuracy and the efficiency of the present method is compared to a previously available approach that employs a multistep method to integrate nonlinear differential equations. It is seen, for the same accuracy, the present approach requires fewer data points. Finally, the TFM for optimal control problems based on Hamiltonian weak formulation is proposed by adopting the p- and hp-versions as a finite element discretization process. The p-version can be used to improve the accuracy of the solution by adding more unknowns to each element without refining the mesh. The usage of hierarchical type of shape functions can lead to a significant saving in computational effort for a given accuracy. A set of Legendre polynomials are chosen as higher order shape functions and applied to two simple minimization problems for optimal control. The proposed formulation provides very accurate results for these problems.Ph. D.
6
Евсина, Наталья Александровна. "Синтез нечеткого регулятора для системы управления процессом сушки капиллярно-пористых материалов". Thesis, НТУ "ХПИ", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/19590.
Повний текст джерелаАнотація:
Диссертация на соискание ученой степени кандидата технических наук по специальности 05.13. 03 - системы и процессы управления. - Национальный технический университет "Харьковский политехнический институт", Харьков, 2015.
Диссертация посвящена разработке и совершенствованию метода синтеза нечеткого регулятора, который обеспечивает заданное качество управления сушкой капиллярно-пористых материалов в конвекционной сушилке периодического действия и позволяет создавать системы управления, опирающиеся на экспертные знания. В диссертационной работе усовершенствован метод анализа чувствительности оптимального управления в линейной системе при квадратичном критерии качества, который позволил получить условия нечувствительности этого управления в замкнутой системе к малым изменениям параметров. Показано, что в общем случае необходимо совместное исследование чувствительности оптимизируемого функционала и чувствительности оптимальной траектории движения. Предложенный в работе алгоритм синтеза нечеткого логического регулятора позволяет использовать стандартную форму описания лингвистических переменных и минимальный набор управляющих правил. В работе выполнена оптимизация параметров и структуры нечетких регуляторов, что позволяет с небольшим количеством управляющих правил решать задачу выбора значений коэффициентов регулятора, который минимизирует критерий качества переходного процесса.The thesis on Candidate Degree in Technical Sciences: Specialty 05.13. 03 - management systems and processes.– National Technical University "Kharkov Polytechnic Institute", Kharkov 2015. This thesis is devoted to the development and improvement of the synthesis method of a fuzzy regulator which ensures the specified quality to control the drying of the capillary and porous materials in a convection oven of periodic action and allows creating the control systems basing on the expert knowledge. The work describes the improved method of the optimal control sensitivity analysis in a linear system with a quadratic quality criterion which allowed obtaining the control insensitivity conditions to a slightly changed parameters in a closed system. Basing on the performed analysis the thesis shows the necessity to perform a joint research of the optimized functionality sensitivity and the sensitivity of the optimal movementtrajectory. The thesis offers a simple synthesis algorithm of the fuzzy and logical regulator which provides the ability to use a standard format describing the linguistic variables and a minimum set of the operating rules. The regulators built on the basis of fuzzy logic in some cases are capable to provide higher quality rates of the transition processes in comparison with classic regulators. Using the synthesis methods of fuzzy control algorithms, it is possible to optimize the difficult control loops omitting mathematical model specification.
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Ramirez, Ivan. "Mathematical Modeling of Immune Responses to Hepatitis C Virus Infection." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2425.
Повний текст джерелаАнотація:
An existing mathematical model of ordinary differential equations was studied to better understand the interactions between hepatitis C virus (HCV) and the immune system cells in the human body. Three possible qualitative scenarios were explored: dominant CTL response, dominant antibody response, and coexistence. Additionally, a sensitivity analysis was carried out to rank model parameters for each of these scenarios. Therapy was addressed as an optimal control problem. Numerical solutions of optimal controls were computed using a forward-backward sweep scheme for each scenario. Model parameters were estimated using ordinary least squares fitting from longitudinal data (serum HCV RNA measurements) given in reported literature.
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Євсіна, Наталя Олександрівна. "Синтез нечіткого регулятора для системи управління процесом сушіння капілярно-пористих матеріалів". Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/19587.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.13. 03 – системи та процеси управління. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2015.
Дисертацію присвячено розробці та вдосконаленню методу синтезу нечіткого регулятора, який забезпечує задану якість управління сушінням капілярно – пористих матеріалів в конвекційній сушарці періодичної дії та дозволяє створювати системи управління, що спираються на експертні знання. Удосконалено метод аналізу чутливості оптимального управління в лінійній системі при квадратичному критерії якості, який дозволив отримати умови нечутливості цього управління в замкнутій системі до малих змін параметрів. Показано, що в загальному випадку необхідно спільне дослідження чутливості функціонала, що оптимізується і чутливості оптимальної траєкторії руху. Запропоновано алгоритм синтезу нечітко-логічного регулятора, що дозволяє використовувати стандартну форму опису лінгвістичних змінних і мінімальний набір керуючих правил. Здійснено синтез нечітких регуляторів з оптимізацією їх параметрів і структури та запропоновано структурну схему нечіткого контролера. В роботі розроблені імітаційні моделі процесу сушіння КПМ, що описують зміну температури і вологості при природній та комбінованої циркуляції сушильного агенту в камерній сушарці періодичної дії, які використовуються для налаштування адаптивних нечітких регуляторів. Синтезований адаптивний нечіткий регулятор стабілізації температури сушильного агенту дозволяє в широкому діапазоні факторів, що збурюють, отримати мінімальний покращений критерій якості системи управління в порівнянні з класичним регулятором.The thesis on Candidate Degree in Technical Sciences: Specialty 05.13. 03 - management systems and processes.– National Technical University "Kharkov Polytechnic Institute", Kharkov 2015. This thesis is devoted to the development and improvement of the synthesis method of a fuzzy regulator which ensures the specified quality to control the drying of the capillary and porous materials in a convection oven of periodic action and allows creating the control systems basing on the expert knowledge. The work describes the improved method of the optimal control sensitivity analysis in a linear system with a quadratic quality criterion which allowed obtaining the control insensitivity conditions to a slightly changed parameters in a closed system. Basing on the performed analysis the thesis shows the necessity to perform a joint research of the optimized functionality sensitivity and the sensitivity of the optimal movementtrajectory. The thesis offers a simple synthesis algorithm of the fuzzy and logical regulator which provides the ability to use a standard format describing the linguistic variables and a minimum set of the operating rules. The regulators built on the basis of fuzzy logic in some cases are capable to provide higher quality rates of the transition processes in comparison with classic regulators. Using the synthesis methods of fuzzy control algorithms, it is possible to optimize the difficult control loops omitting mathematical model specification.
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Rockenfeller, Robert [Verfasser], Thomas [Akademischer Betreuer] [Gutachter] Götz, and Jörg [Gutachter] Fehr. "On the application of mathematical methods in Hill-type muscle modeling: stability, sensitivity and optimal control / Robert Rockenfeller. Betreuer: Thomas Götz. Gutachter: Thomas Götz ; Jörg Fehr." Koblenz, 2016. http://d-nb.info/111089550X/34.
Повний текст джерела
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Seelbinder, David [Verfasser], Christof [Akademischer Betreuer] [Gutachter] Büskens, and Stephan [Gutachter] Theil. "On-board Trajectory Computation for Mars Atmospheric Entry Based on Parametric Sensitivity Analysis of Optimal Control Problems / David Seelbinder ; Gutachter: Christof Büskens, Stephan Theil ; Betreuer: Christof Büskens." Bremen : Staats- und Universitätsbibliothek Bremen, 2017. http://d-nb.info/1141277700/34.
Повний текст джерела
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Elfstadius, Martin, and Daniel Gecer. "Method to Detect and Measure Potential Market Power Caused by Transmission Network Congestions on Electricity Markets." Thesis, Linköping University, Department of Electrical Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-12133.
Повний текст джерелаАнотація:
This thesis is based on studies of the deregulated electricity markets located in the United States of America. The problem statement of the thesis evolved continuously throughout our initial period of research. Focus was finally put on monitoring and detection of potential market power caused by congestion in the transmission network. The existence of market power is a serious concern in today’s electric energy markets. A system that monitors the trading is needed and much research and many proposals on how to deal with this problem have been introduced over the years. We focus on some of these approaches and develop an approach of our own, which we call “Monopolistic Energy Calculation”. We adopt the idea to identify participants with the ability to raise prices without losing market share. An ability that should not be present on a competitive market. We take this idea further by identifying participants with the ability to make considerable price raises without losing all market shares. We propose a way to calculate the remaining market shares (Monopolistic Energy Levels) after a large price raise. These calculated levels of energy, that are only deliverable by a certain participant or by a certain group of participants, are caused by the active congestions in the network.
The approach detects the amounts of these energy levels and the location in the network at which they are present. This is a prospective method if used with a prediction of the following day’s demand, which is regularly available with high accuracy. The method can also be used for monitoring purposes to identify critical situations in real-time. The method is implemented and two sets of simulations are done in which we explain and evaluate the approach. The results are promising and the correlation between “Monopolistic Energy” and market power is confirmed.
Detta examensarbete är baserat på studier av de deregulerade electricitsmarknaderna i USA. Problemformuleringen var i början av detta arbete inte definitiv, utan utvecklades under en längre inledande fas av forskningsarbete. Slutligen kunde vi faställa att detektion av potentiell marknadskraft på elektricitetsmarknaden, orsakat av överbelastningar i transmissionnätverket, var av särskilt intresse. Ett system som övervakar handeln och förekomster av orättvisor orsakat av detta är nödvändigt. Det har de senaste åren gjorts mycket forskning inom detta område. Baserat på denna forskning utvecklades sedan ett eget förslag, som vi kallar ”Monopolistic Energy Calculations”. Vissa tidigare förslag på hur problemet kan angripas blev av särskilt intresse. En idé från dessa var att identifiera marknadsaktörer med förmågan att höja priser utan att förlora marknadsandelar, en icke önskvärd egenskap hos aktörer då en konkurrenskraftig marknad är eftertraktad.
Vi tar denna idé ett steg längre genom att identifiera marknadsaktörer med förmågan att höja priser signifikant utan att förlora alla marknadsandelar. Vi föreslår ett sätt att beräkna dessa energinivåer som endast är möjliga att levereras av en eller ett fåtal särskilda aktörer, som direkt följd av de aktiva stockningarna i nätverket, under antagandet av en inelastisk efterfrågan. Vi föreslår ett sätt att beräkna de återstående marknadsandelarna (Monopolistic Energy Levels) efter en stor prishöjning. Vår metod beräknar mängden av denna energi och var i nätverket dessa mängder förekommer. Denna metod kan sia om framtida problem om en estimering av morgondagens efterfråga används. Sådana estimeringar görs idag
regelbundet med hög träffsäkerhet. Metoden kan även användas i realtid för upptäckt av kritiska marknadssituationer. Simuleringar av detta görs som förklarar vår lösning och utvärderar den. Resultaten är lovande och korrelationen mellan ”Monopolistisk Energi” och marknadskraft är bekräftade.
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Schattel, Anne Sarah [Verfasser], Christof [Akademischer Betreuer] Büskens, Christof [Gutachter] Büskens, and Marco [Gutachter] Scharringhausen. "Dynamic Modeling and Implementation of Trajectory Optimization, Sensitivity Analysis, and Optimal Control for Autonomous Deep Space Navigation / Anne Sarah Schattel ; Gutachter: Christof Büskens, Marco Scharringhausen ; Betreuer: Christof Büskens." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1167925777/34.
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Xausa, Ilaria [Verfasser], Matthias [Akademischer Betreuer] Gerdts, and Olivier [Akademischer Betreuer] Bokanowski. "Verification of Collision Avoidance Systems using Optimal Control and Sensitivity Analysis / Ilaria Xausa. Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik. Betreuer: Matthias Gerdts. Gutachter: Matthias Gerdts ; Olivier Bokanowski." Neubiberg : Universitätsbibliothek der Universität der Bundeswehr München, 2015. http://d-nb.info/1081029749/34.
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Xausa, Ilaria Verfasser], Matthias [Akademischer Betreuer] [Gerdts, and Olivier [Akademischer Betreuer] Bokanowski. "Verification of Collision Avoidance Systems using Optimal Control and Sensitivity Analysis / Ilaria Xausa. Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik. Betreuer: Matthias Gerdts. Gutachter: Matthias Gerdts ; Olivier Bokanowski." Neubiberg : Universitätsbibliothek der Universität der Bundeswehr München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:706-4394.
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Vyambwera, Sibaliwe Maku. "Mathematical modelling of the HIV/AIDS epidemic and the effect of public health education." Thesis, University of Western Cape, 2014. http://hdl.handle.net/11394/3360.
Повний текст джерелаАнотація:
>Magister Scientiae - MScHIV/AIDS is nowadays considered as the greatest public health disaster of modern time. Its progression has challenged the global population for decades. Through mathematical modelling, researchers have studied different interventions on the HIV pandemic, such as treatment, education, condom use, etc. Our research focuses on different compartmental models with emphasis on the effect of public health education. From the point of view of statistics, it is well known how the public health educational programs contribute towards the reduction of the spread of HIV/AIDS epidemic. Many models have been studied towards understanding the dynamics of the HIV/AIDS epidemic. The impact of ARV treatment have been observed and analysed by many researchers. Our research studies and investigates a compartmental model of HIV with treatment and education campaign. We study the existence of equilibrium points and their stability. Original contributions of this dissertation are the modifications on the model of Cai et al. [1], which enables us to use optimal control theory to identify optimal roll-out of strategies to control the HIV/AIDS. Furthermore, we introduce randomness into the model and we study the almost sure exponential stability of the disease free equilibrium. The randomness is regarded as environmental perturbations in the system. Another contribution is the global stability analysis on the model of Nyabadza et al. in [3]. The stability thresholds are compared for the HIV/AIDS in the absence of any intervention to assess the possible community benefit of public health educational campaigns. We illustrate the results by way simulation The following papers form the basis of much of the content of this dissertation, [1 ] L. Cai, Xuezhi Li, Mini Ghosh, Boazhu Guo. Stability analysis of an HIV/AIDS epidemic model with treatment, 229 (2009) 313-323. [2 ] C.P. Bhunu, S. Mushayabasa, H. Kojouharov, J.M. Tchuenche. Mathematical Analysis of an HIV/AIDS Model: Impact of Educational Programs and Abstinence in Sub-Saharan Africa. J Math Model Algor 10 (2011),31-55. [3 ] F. Nyabadza, C. Chiyaka, Z. Mukandavire, S.D. Hove-Musekwa. Analysis of an HIV/AIDS model with public-health information campaigns and individual with-drawal. Journal of Biological Systems, 18, 2 (2010) 357-375. Through this dissertation the author has contributed to two manuscripts [4] and [5], which are currently under review towards publication in journals, [4 ] G. Abiodun, S. Maku Vyambwera, N. Marcus, K. Okosun, P. Witbooi. Control and sensitivity of an HIV model with public health education (under submission). [5 ] P.Witbooi, M. Nsuami, S. Maku Vyambwera. Stability of a stochastic model of HIV population dynamics (under submission).
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Clérin, Jean-Marc. "Problèmes de contrôle optimal du type bilinéaire gouvernés par des équations aux dérivées partielles d’évolution." Thesis, Avignon, 2009. http://www.theses.fr/2009AVIG0405/document.
Повний текст джерелаАнотація:
Cette thèse est une contribution à l’étude de problèmes de contrôle optimal dont le caractère non linéaire se traduit par la présence, dans les équations d’état, d’un terme bilinéaire relativement à l’état et au contrôle. Malgré les difficultés liées à la non linéarité, nous obtenons des propriétés spécifiques au cas bilinéaire. L’introduction générale constitue la première partie. La seconde partie est consacrée à l’étude des équations d’état ; ce sont des équations aux dérivées partielles d’évolution. Nous établissons des estimations a priori sur les solutions à partir des inégalités de Willett et Wong et nous démontrons que les équations d’états sont bien posées. Dans le cas où les contrôles subissent une contrainte liée aux états, ces estimations permettent de déduire l’existence de solutions dans le cadre des inclusions différentielles. Les troisième et quatrième parties de ce mémoire sont dévolues à la démonstration de l’existence de contrôles optimaux, puis à l’analyse de la sensibilité relative à une perturbation qui intervient de façon additive dans l’équation d’état. Le caractère bilinéaire permet de vérifier des conditions suffisantes d’optimalité du second ordre. Nous fournissons sur des exemples, une formule explicite des dérivées directionnelles de la fonction valeur optimaleThis thesis is devoted to the analysis of nonlinear optimal control problems governed by an evolution state equation involving a term which is bilinear in state and control. The difficulties due to nonlinearity remain, but bilinearity adds a lot of structure to the control problem under consideration. In Section 2, by using Willet and Wong inequalities we establish a priori estimates for the solutions of the state equation. These estimates allow us to prove that the state equation is well posed in the sense of Hadamard. In the case of a feedback constraint on the control, the state equation becomes a differential inclusion. Under mild assumptions, such a differential inclusion is solvable. In Section 3, we prove the existence of solutions to the optimal control problem. Section 4 is devoted to the sensitivity analysis of the optimal control problem. We obtain a formula for the directional derivative of the optimal value function. This general formula is worked out in detail for particular examples
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Guebeli, Markus. "Optimum efficiency control of the CTX powertrain." Thesis, University of Bath, 1993. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359851.
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Artiges, Nils. "De l'instrumentation au contrôle optimal prédictif pour la performance énergétique du bâtiment." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT003/document.
Повний текст джерелаАнотація:
Face aux forts besoins de réduction de la consommation énergétique et de l’impact environnemental,le bâtiment d’aujourd’hui vise la performance en s’appuyant sur des sourcesd’énergie de plus en plus diversifiées (énergies renouvelables), une enveloppe mieux conçue(isolation) et des systèmes de gestion plus avancés. Plus la conception vise la basse consommation,plus les interactions entre ses composants sont complexes et peu intuitives. Seule unerégulation plus intégrée permettrait de prendre en compte cette complexité et d’optimiser lefonctionnement pour atteindre la basse consommation sans sacrifier le confort.Les techniques de commande prédictive, fondées sur l’utilisation de modèles dynamiqueset de techniques d’optimisation, promettent une réduction des consommations et de l’inconfort.Elles permettent en effet d’anticiper l’évolution des sources et des besoins intermittentstout en tirant parti de l’inertie thermique du bâtiment, de ses systèmes et autres élémentsde stockage. Cependant, dans le cas du bâtiment, l’obtention d’un modèle dynamique suffisammentprécis présente des difficultés du fait d’incertitudes importantes sur les paramètresdu modèle et les sollicitations du système. Les avancées récentes dans le domaine de l’instrumentationdomotique constituent une opportunité prometteuse pour la réduction de cesincertitudes, mais la conception d’un tel système pour une telle application n’est pas triviale.De fait, il devient nécessaire de pouvoir considérer les problématiques de monitoring énergétique,d’instrumentation, de commande prédictive et de modélisation de façon conjointe.Cette thèse vise à identifier les liens entre commande prédictive et instrumentation dansle bâtiment, en proposant puis exploitant une méthode générique de modélisation du bâtiment,de simulation thermique et de résolution de problèmes d’optimisation. Cette méthodologiemet en oeuvre une modélisation thermique multizone du bâtiment, et des algorithmesd’optimisation reposant sur un modèle adjoint et les outils du contrôle optimal. Elle a étéconcrétisée dans un outil de calcul permettant de mettre en place une stratégie de commandeprédictive comportant des phases de commande optimale, d’estimation d’état et decalibration.En premier lieu, nous étudions la formulation et la résolution d’un problème de commandeoptimale. Nous abordons les différences entre un tel contrôle et une stratégie de régulationclassique, entre autres sur la prise en compte d’indices de performance et de contraintes. Nousprésentons ensuite une méthode d’estimation d’état basée sur l’identification de gains thermiquesinternes inconnus. Cette méthode d’estimation est couplée au calcul de commandeoptimale pour former une stratégie de commande prédictive.Les valeurs des paramètres d’un modèle de bâtiment sont souvent très incertaines. Lacalibration paramétrique du modèle est incontournable pour réduire les erreurs de prédictionet garantir la performance d’une commande optimale. Nous appliquons alors notreméthodologie à une technique de calibration basée sur des mesures de températures in situ.Nous ouvrons ensuite sur des méthodes permettant d’orienter le choix des capteurs à utiliser(nombre, positionnement) et des paramètres à calibrer en exploitant les gradients calculéspar la méthode adjointe.La stratégie de commande prédictive a été mise en oeuvre sur un bâtiment expérimentalprès de Chambéry. Dans le cadre de cette étude, l’intégralité du bâtiment a été modélisé,et les différentes étapes de notre commande prédictive ont été ensuite déployées de mainière séquentielle. Cette mise en oeuvre permet d’étudier les enjeux et les difficultés liées àl’implémentation d’une commande prédictive sur un bâtiment réel.Cette thèse est issue d’une collaboration entre le CEA Leti, l’IFSTTAR de Nantes et leG2ELab, et s’inscrit dans le cadre du projet ANR PRECCISIONMore efficient energy management of buildings through the use of Model Predictive Control(MPC) techniques is a key issue to reduce the environmental impact of buildings. Buildingenergy performance is currently improved by using renewable energy sources, a betterdesign of the building envelope (insulation) and the use of advanced management systems.The more the design aims for high performance, the more interactions and coupling effectsbetween the building, its environment and the conditions of use are important and unintuitive.Only a more integrated regulation would take in account this complexity, and couldhelp to optimize the consumption without compromising the comfort.Model Predictive Control techniques, based on the use of dynamic models and optimizationmethods, promise a reduction of consumption and discomfort. They can generate energysavings by anticipating the evolution of renewable sources and intermittent needs, while takingadvantage of the building thermal inertia and other storage items. However, in the caseof buildings, obtaining a good dynamic model is tough, due to important uncertainties onmodel parameters and system solicitations.Recent advances in the field of wireless sensor networks are fostering the deployment ofsensors in buildings, and offer a promising opportunity to reduce these errors. Nevertheless,designing a sensor network dedicated to MPC is not obvious, and energy monitoring,instrumentation, modeling and predictive control matters must be considered jointly.This thesis aims at establishing the links between MPC and instrumentation needs inbuildings. We propose a generic method for building modeling, thermal simulation andoptimization. This methodology involves a multi-zone thermal model of the building, andefficient optimization algorithms using an adjoint model and tools from the optimal controltheory. It was implemented in a specific toolbox to develop a predictive control strategywith optimal control phases, state estimation phases and model calibration.At first, we study the formulation and resolution of an optimal control problem. We discussthe differences between such a control and a conventional regulation strategy, throughperformance indicators. Then, we present a state estimation method based on the identificationof unknown internal gains. This estimation method is subsequently coupled with theoptimal control method to form a predictive control strategy.As the parameters values of a building model are often very uncertain, parametric modelcalibration is essential to reduce prediction errors and to ensure the MPC performance. Consequently,we apply our methodology to a calibration technique based on in situ temperaturemeasurements. We also discuss how our approach can lead to selection techniques in orderto choose calibrated parameters and sensors for MPC purposes.Eventually, the predictive control strategy was implemented on an experimental building,at CEA INES, near Chambéry. The entire building was modeled, and the different steps ofthe control strategy were applied sequentially through an online supervisor. This experimentgave us a useful feedback on our methodology on a real case.This thesis is the result of a collaboration between CEA Leti, IFSTTAR Nantes andG2ELab, and is part of the ANR PRECCISION project
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Silva, André Luís da. "Nonlinear optimum model following control of flexible aircraft." Instituto Tecnológico de Aeronáutica, 2010. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1099.
Повний текст джерелаАнотація:
This Doctorate Thesis concerns optimum control of flexible aircraft. Models of a conceptual flexible aircraft are developed for control applications. A general model following problem via output feedback is developed and applied to the conceptual aircraft. The models are determined for 3 aircraft variants with increasing flexibility. The aerodynamics of flexible body is given by the Doublet Lattice method. The dynamics of the flexible structure is obtained via modal superposition. Controllability measures, given from control amplitude and rate constraints, are evaluated. Stabilization of flexible modes is performed via static output feedback. Control channels are defined with support of modal controllability and observability indexes. These applications contribute to determine the configuration of control surfaces. In order to treat the control of flexible aircraft, a rigid body approximation is proposed as the reference model. A general problem is posed, that consists in the determination of an optimum quadratic nonlinear output feedback for nonlinear plant and reference model, in order to approximate the input-output behavior of the reference model, for given performance outputs. Novel optimum and sub-optimum results, involving time variant and invariant linear state and output feedback and nonlinear time invariant output feedback, via neural networks, are developed. All these results are applied to the nonlinear model of conceptual aircraft and respective linear approximation, with comparisons among them. The efficiency and efficacy of the results are shown, and the importance of the nonlinear control is evidenced.
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Smith, G. Clark II. "Optimum Actuator Grouping in Feedforward Active Control Applications." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/36561.
Повний текст джерелаАнотація:
Previous work has demonstrated the benefit of grouping actuators to increase the controllability of an active control system, without increasing the number of control channels. By driving two or more secondary sources with the same control input, one is also able to reduce the hardware cost and complexity. In this work, a time domain cost function is developed for on-line actuator grouping and active structural acoustic control (ASAC) of a simply-supported beam excited with a broadband disturbance. Three PZT actuators are mounted on the beam structure to control the wavenumber components corresponding to five radiation angles. The propagation angles are selected to represent the total radiated sound power. The point force disturbance is bandlimited random noise which encompasses the first three modes of beam vibration. Actuators are considered grouped when their compensators are equal. Therefore, the cost function presented here incorporates an additional non-quadratic term which penalizes the controller for differences between the feedforward compensator coefficients. The backpropagation neural network algorithm provides the proper procedure to determine the minimum of this cost function.
The main disadvantage of using a stochastic gradient technique, while searching the prescribed control surface, is convergence to local minima. In this thesis, a resolution to this problem is suggested which incorporates using a variety of initial conditions. Two initialization conditions are considered: grouping actuators based upon weights determined by converging the filtered-x LMS algorithm and simultaneously grouping and controlling with the compensator weights initialized to small arbitrary numbers. Test cases of heavy and light grouping parameters were evaluated from both initial conditions. The computer simulations demonstrate the ability of this new form of the cost function to group actuators and control the error response with either initial condition. The heavy grouping cases achieved the same one channel control system from both initial conditions. The performance of the one channel solution was 1.5 dB lower than the performance of the ungrouped filtered-x LMS solution. The ability to select the different levels of grouping was demonstrated when the algorithm was initialized with the filtered-x LMS weights and run with light grouping parameters. For this case, the on-line algorithm grouped two actuators, but allowed the third actuator to exist independently. The performance of the two channel control system was only 0.6 dB less than the performance of the filtered-x LMS solution. In all grouping cases investigated, the convergence times of the grouping algorithm were within the same order as for the filtered-x LMS algorithm. The effect of uncorrelated error sensor noise on the actuator groupings is also briefly discussed.Master of Science
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Spagnoli, Bruno. "Etude numérique de sensibilité et contrôle optimal du bruit aéroacoustique généré par une couche de mélange compressible bidimensionnelle." Toulouse 3, 2006. http://www.theses.fr/2006TOU30254.
Повний текст джерелаАнотація:
Une couche de mélange compressible bidimensionnelle est simulée numériquement par Simulation Numerique Directe (DNS) des équations de Navier-Stokes, afin d'en extraire le rayonnement aéroacoustique. Cet écoulement constitue un modèle simplifié de jet, dont on cherche à réduire le bruit émis par application de la théorie du contrôle optimal. Après validation de ce modèle, les équations adjointes des équations de Navier-Stokes sont numériquement résolues afin d'étudier dans un premier temps la sensibilité du rayonnement acoustique de la couche de mélange à différents forçages. Cette étude nous indique que le bruit émis est particulièrement sensible à un forçage à basse fréquence appliqué au niveau de la naissance de la couche. En outre, la sensibilité relative est maximale pour un forçage «massique», sur l'équation de continuité. A partir de ces résultats, nous mettons en place une stratégie de contrôle optimal basée sur la minimisation d'une fonctionnelle-objectif formulée pour réduire le bruit sur une zone cible prédéterminée. Le gradient de cette fonctionnelle en fonction du forçage est fourni par la connaissance de l'état adjoint. L'espace des forçages à explorer est choisi à partir des résultats de l'étude de sensibilité. Un algorithme de gradient conjugué est appliqué pour chercher le forçage optimal qui minimise la fonctionnelle. Les résultats nous donnent une diminution de celle-ci de l'ordre de 10% pour une zone cible large, et de 75% pour une zone cible réduite. Ces résultats sont comparés avec une étude semblable récente, et des interprétations et perspectives sont développéesThe aeroacoustic radiation of a two-dimensional compressible mixing layer is computed using Direct Numerical Simulation (DNS) of the Navier-Stokes equations. This flow constitutes a simplified model for a jet. The goal is to reduce the radiated noise using optimal control theory. Following the validation of the DNS model, the adjoint of the compressible Navier-Stokes equations are numerically solved in order to study the sensitivity of the noise to several forcings. This study shows that the flow noise is particularly sensitive to a low-frequency forcing applied near the origin of the mixing layer. In addition, the relative sensitivity is maximum for a ``mass'' forcing, on the continuity equation. From these results, we set an optimal control strategy aimed at minimizing an objective functional formulated to reduce the noise over a pre-determined target. The gradient of this functional with respect to the forcing is given by the adjoint state. The forcing space to explore is chosen using the results of the sensitivity study. A conjugate gradient algorithm is used to search for the functional minimum. Our results give a 10 % reduction of the functional for a large target, and a 75 % reduction for a small target. These results are compared to a recent similar study, and some interpretations and perspectives are given
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Kozica, Ermin. "Look Ahead Cruise Control: Road Slope Estimation and Control Sensitivity." Thesis, KTH, Reglerteknik, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107527.
Повний текст джерелаАнотація:
Look ahead cruise control is a relatively new concept. It deals with the possibility of making use of recorded road slope data in combination with GPS, inorder to improve vehicle cruise control. This thesis explores the possibility ofestimating road slope as well as investigating the sensitivity of two look aheadcontrollers, with respect to errors in estimation of mass, wheel radius and roadslope. A filter using GPS and standard vehicle sensors is used for estimation ofroad slope. The filter is robust to losses in data since redundant information isavailable. Possible errors in estimation caused by the filter are identified. Two previously published look ahead controllers using different strategies tocontrol a heavy vehicle are investigated. A description of controller behaviourin perfect conditions is presented. Sensitivity analysis is performed identifyingerroneous control behaviour inflicted by errors in the used vehicle model androad slope. Further, effects on controllers caused by errors in road slope estimation estimation are detected. Conclusions about the two look ahead strategiesare drawn.
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Flamm, David Simson. "Control of delay systems for minimax sensitivity." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/15082.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Vita.
Bibliography: leaves 161-162.
by David S. Flamm.
Ph.D.
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Blomberg, Joel. "Sensitivity study of control rod depletion coefficients." Thesis, Uppsala universitet, Tillämpad kärnfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256092.
Повний текст джерелаАнотація:
This report investigates the sensitivity of the control rod depletion coefficients, Sg, to different input parameters and how this affects the accumulated 10B depletion, β. Currently the coefficients are generated with PHOENIX4, but the geometries can be more accurately simulated in McScram. McScram is used to calculate Control Rod Worth, which in turn is used to calculate Nuclear End Of Life, and Sg cannot be generated in the current version of McScram. Therefore, it is also analyzed whether the coefficients can be related to CRW and thus be studied indirectly through it. Simulations of the coefficients were done in PHOENIX4, simulations of CRW were done in both PHOENIX4 and McScram and simulations of β were done in POLCA7. All simulations were performed for a CR99 in a BWR reactor. The control rod coefficients were found to be sensitive to the enrichment of the fuel, void fraction of the water and the width of the gap, and these effects were also seen in the results of β. As a result, one of three steps could be taken. First, the parameter values should not be set arbitrarily, instead default values could be chosen such that Sg is calculated more accurately. Second, a set of tables of Sg could be generated for different parameter values so that β can be calculated with Sg from the current conditions, although this would mean that PHOENIX4 needs to be updated. Third, McScram can be updated to be able to calculate Sg directly. It has been concluded that Sg cannot be studied indirectly through CRW since the trends and the sensitivity to the different parameters were not consistent between Sg, CRW calculated with PHOENIX4 and CRW calculated with McScram, where PHOENIX4 was more sensitive than McScram. The results can instead be used to bench-mark the PHOENIX4 results.
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Cai, Xinbo [Verfasser]. "Optimum Control of Electrical Drives and Power Converters : Computational Efficient Optimum Control for Three-Level-Inverters with DC-link Capacitance Balancing / Xinbo Cai." Düren : Shaker, 2021. http://d-nb.info/1233548417/34.
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Schuetze, Manfred Richard. "Integrated simulation and optimum control of the urban wastewater system." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266011.
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Ho, John Rong Ming. "Higher-order kinematic error sensitivity analysis and optimum dimensional tolerancing of dyad and non-dyad mechanisms." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq23340.pdf.
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Aweya, James. "Sensitivity methods for congestion control in computer networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0021/NQ48085.pdf.
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Chopra, Avnish. "Robust control via higher order trajectory sensitivity minimization." Ohio : Ohio University, 1994. http://www.ohiolink.edu/etd/view.cgi?ohiou1176842246.
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Cooper, Sean. "Control of a satellite based photovoltaic array for optimum power draw." Worcester, Mass. : Worcester Polytechnic Institute, 2008. http://www.wpi.edu/Pubs/ETD/Available/etd-042808-104913/.
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Counsell, John Mark. "Optimum and safe control algorithim (OSCA) for modern missile autopilot design." Thesis, Lancaster University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332382.
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Ho, Wai Fuk. "Air-conditioning system design for optimum control performance in Hong Kong." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/7242.
Повний текст джерелаАнотація:
Studies on design for control optimization of air-conditioning (a/c) system for better performance in Hong Kong are reported in this thesis. Typical plant configuration data was collected from an in-depth survey of a/c systems and control used in Hong Kong. Control performance has been used for the first time as an objective for optimizing a/c system designs. The study investigates and illustrates that optimization of a/c systems for application in the Hong Kong by simulation is promising and flexible. The accuracy of simulation is enhanced by using the survey data. The survey shows that some a/c control systems and their control strategies are not well considered in the design stage and their operation and set-up are not properly addressed. Hence, there exists optimization opportunities in the a/c system design and control strategies for a/c systems used in Hong Kong. Parameters affecting the control performance of a/c systems were investigated by carrying out experiments. Identified parameters are the objective function of optimization, controller settings, control valve and drive and, in case of direct digital control, sampling rate. The influence of these factors on the control performance is an essential consideration for the entire optimization process. Strategies in applying the findings in optimizing an a/c system for control performance by simulation were developed and suggested. This study provides platform for further simulation study of optimization in both methodologies and control strategies for a/c system design and operation.
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cooper, sean. "Control of a Satellite Based Photovoltaic Array for Optimum Power Draw." Digital WPI, 2008. https://digitalcommons.wpi.edu/etd-theses/414.
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This thesis analyzes the general performance and design requirements of photovoltaic(PV) systems, and specifically how they relate to the design of a system intended to supply power to a rotating satellite. The PV array geometry was discussed, different DC-DC converter topologies were analyzed, and optimum array geometry and converter topologies were determined. The potential reference quantities for use in control of the system are examined. Due to its comparably greater linearity with respect to changes in apparent load and its relative insensitivity to insolation changes, voltage was determined to be the best reference quantity for use in stable tracking of the maximum power operating point of photovoltaic modules. The preceding work is used to design and model a photovoltaic system for a rotating satellite ensuring the supply of the maximum available power as well as stable operation. Simulations of the system are performed at rotational velocities up to 300 rev/min and its behavior is analyzed to demonstrate the validity of the preceding work. It was concluded that: ● parallel connected photovoltaic panels provide greater efficiency than series connected panels. ● Buck, Boost, and Cuk Converter architectures are best suited to PV applications ● PV Voltage is the best reference quantity for use in stable control of PV systems.
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Rodríguez-Dávila, Héctor M. "Optimum design for feedforward structural-acoustic control of complex structural systems." Diss., Virginia Tech, 1996. http://hdl.handle.net/10919/40254.
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Chung, Tak Shing. "An integrated approach incorporating dynamic and static security limits in optimum power dispatch." Thesis, University of Strathclyde, 1993. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=20375.
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Optimum power dispatch is performed in a power system to determine the most economic power dispatch condition for a certain system loading. In this thesis the main focus is on the investigation of this problem and its improved application by including both dynamic security and static security limits in its solution. The aim is to develop an efficient and practical on-line method of optimum power dispatch with due regard to the necessary security requirements. A critical review of the current practices of security and optimization in power system operation shows that they are essential elements in Energy Management System computer softwares. Since optimality and security present conflicting requirements on system operation, it is both logical and beneficial to develop an integrated approach to satisfy all the security limits in optimum dispatch. The classical approach to consider only the static security limits in optimum dispatch calculation is found to be insufficient in providi ng the essential informations on the dynamic security performance. This problem is causing increasing concern with the recent trend to load power systems more closer to their stability limits in order to achieve maximum economy. A new formulation of the security constrained optimum dispatch problem with an integrated approach to consider both dynamic and static security limits is thus proposed in this thesis. The Optimum Power Flow ( OPF ) formulation uses a Recursive Quadratic Programming algorithm applied in the compact modelling of the system. This formulation consists of a decoupling process of the active and reactive power optimizations. The investigation into on-line security control shows that insufficient attention on dynamic security in present practice could endanger the system integrity in the contingency state. This leads to the development of a new scheme to integrate both dynamic and static security assessments. Direct application of classical transient stability assessment methods using numerical integration of swing equations is found to be too slow and a new method based on reduced dynamic equivalent is investigated. The method is based on an efficient dynamic security assessment scheme which assesses the on-line operating state of the system. A dynamic security margin is defined to measure the robustness of the system when it is subjected to a selected scenario of dynamic contingency. The method also identifies the critical machine or cluster of machines that would cause transient instability, and proposes preventive control strategies to improve the dynamic security performance. This is integrated in the approach as a preventive control module. The module aims to prevent the system from reaching probable system collapse due to contingency that could cause cascading tripouts in the system. Extensive simulation tests are performed using the approach in several example networks together with validation case studies compared to full load flow and transient stability tests. The results demonstrate that the approach is fast and reliable with good potential for on-line application in stability limited power systems.
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SOUZA, LINDOMAR JACINTO DE. "VOLTAGE CONTROL SENSITIVITY CALCULATION FOR VOLTAGE STABILITY OPERATIONAL REINFORCEMENT." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10165@1.
Повний текст джерелаАнотація:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROFUND DE AMPARO A PESQUISA E AO DESENV CIENTIF E TECNO DO MA
O problema de estabilidade de tensão está intimamente ligado à falta de recursos e questões ambientais que limitam a expansão do sistema de transmissão. Esta realidade em conjunto com o crescimento da carga submete os sistemas elétricos a carregamentos pesados, podendo levar a situações de colapso de tensão. O desenvolvimento de métodos para avaliação do carregamento da rede de transmissão tornou-se necessário e imprescindível para que se possa entender o funcionamento do sistema nestas condições e possibilitar a sua operação de modo correto. Em relatório de força-tarefa internacional está explicitada a necessidade de uma ferramenta computacional capaz de verificar a eficácia das ações de controle de tensão na operação do sistema elétrico em tempo-real. Com esse objetivo, foi desenvolvida uma ferramenta computacional com base no sistema linearizado das equações de fluxo de carga, e de todas as outras equações de controles e limites, julgadas pertinentes, para avaliação do efeito das ações de controle de tensão. Determinase uma matriz de sensibilidade [VCS], voltage control sensitivity matrix, através da qual se pode estabelecer a relação existente entre as tensões controladas e as grandezas controladoras. Os elementos diagonais relacionam a grandeza controladora de cada equipamento com a respectiva tensão controlada. A análise do sinal desses elementos estabelece se uma determinada ação de controle será adequada ou não, isto é, se terá efeito esperado ou oposto. Os elementos fora da diagonal representam a interdependência existente entre os equipamentos controladores de tensão. A matriz de sensibilidade também permite que ações de controle de tensão sejam calculadas com o objetivo de mover um ponto de operação inadequado, ou que esteja suscetível à inadequacidade do controle de tensão, colocando-os em um ponto de operação seguro, onde ações operativas de controle de tensão tenham o efeito esperado. Os resultados da avaliação do método desenvolvido e aplicado a sistemas-teste e reais foram qualitativamente coerentes com aqueles obtidos pela resolução (analítica, iterativa por Newton ou iterativa continuada) das equações de fluxo de carga, validando a proposta. A dimensão da matriz [VCS] é proporcional ao número de barras com tensão controlada em análise. Esta matriz não é esparsa e então, quando utilizada para representar o controle de tensão realizado por um número elevado de equipamentos controladores, sua análise direta pode se tornar complexa. Portanto, uma análise baseada nos autovalores e autovetores associados à matriz [VCS] é aplicada objetivando identificar barras de tensão controlada com efeito reverso, ocorrendo de modo contrário ao esperado, e a existência de controles conflitantes. Buscam-se autovalores negativos, nulos ou próximos de zero. A localização das barras com problemas se dá através do exame dos autovetores e fatores de participação associados a esses autovalores. O cálculo e a análise da matriz de sensibilidade dos controles de tensão são executados de forma extremamente rápida e, portanto, o esforço computacional não impede que a ferramenta desenvolvida possa ser usada durante a operação em tempo-real.
The voltage stability problem has been associated with environment questions and lack of financial resources for transmission system expansion. This reality together with the load growth makes the electrical system to be subject of heavy loadings, what can lead to situations of voltage collapse. The development of methods for evaluation of transmission network loading became necessary and indispensable in order to correct operation of the system under heavy loading conditions. In an international force-task report it is stated the need for analytical tools capable of verifying the voltage control action adequacy in the real-time operation. This work reports the development of a computation tool able to evaluate the effect of voltage control actions on the voltage itself. It is based the linearized load flow equations, including control and limit equations judged pertinent. The tool establishes a sensitive matrix, named [VCS] for voltage control sensitivity matrix, that relates the controlling variables and the controlled voltages. Through the analysis of the sign of each diagonal element, it is possible to know whether a specific control action is adequate or not. Moreover, the off-diagonal elements represent the interdependence among the voltage controller devices of the power system under analysis. The sensitivity matrix also allows the calculation of control actions necessary to move the operating point from an unstable area, or near by, to a secure operating region where all voltage control actions would have the expected effect. The results obtained with the voltage control sensitivity matrix applied on real and test-systems was qualitatively coherent with those calculated by analytical, iteractive by Newton-Raphson and/or continuationiteractive solution of power flow equations, validating the proposed method. The [VCS] dimension is proportional to the number of buses with controlled voltage in the system area under analysis. The matrix is not sparse and when there are a large number of voltage control equipments, its immediate analysis may be complex. Therefore, an analysis based on eigenvalues and eigenvectors associated with [VCS] matrix is used in order to identify voltage control action with opposite effect. In this case, the analysis is focused on negative eigenvalues. The identification of conflicting controls existence of any system area under analysis is a by-product. The voltage control sensitivity matrix computation and analysis are performed extremely fast. Therefore, the computational effort does not constrain its use in real-time operation.
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de, Castro Germano Andresa Mara. "Biomechanical aspects of sensitivity in relationship with motor control." Doctoral thesis, Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-217339.
Повний текст джерелаАнотація:
The central integration of sensory information provided by various afferent receptors is required to control human movement. Although the function of individual afferent receptors is known, the complexity and interactivity of afferent information remains unclear, especially in scenarios which involve the reduction of information provided by one or more afferent receptors. Reduced plantar sensitivity is commonly associated with postural instability, which occurs in ageing, peripheral neuropathies, and other neurological disorders like Parkinson's disease. Although there has been a great advance in understanding afferent inputs during recent years, the role of afferent information in controlling movement is still unclear. Therefore, the aim of the present thesis is to investigate the effects of reduced plantar sensitivity on quasi-static and dynamic balance control, as well as muscle reflexes. The current thesis is comprised of five experiments. Two experiments were designed as preliminary investigations, while the remaining three experiments addressed the main questions of this thesis. The first experiment investigated a basic question about subjective foot sensitivity (vibration perception) measured in two different body positions: standing and sitting. Results of Experiment I showed no differences of vibration perception between both measured conditions. Therefore, comparing data from plantar sensitivity vibration tests performed during sitting and during standing (e.g. balance) is feasible. In Experiment II, the role of afferent information from plantar mechanoreceptors on quasi-static balance was investigated using two different cooling procedures: a permanently cooling thermal platform and conventional ice pads. COP total excursions, plantar temperatures, and scores of a Visual Analogue Scale (VAS) regarding subjective pain were analyzed. Experiment II demonstrated that constant and controllable cooling via the thermal platform is the superior approach with respect to subjective pain (VAS) and to reach and maintain the desired temperature throughout the trials. Furthermore, only cooling via the thermal platform induced postural instability, revealed by increased COP values. This instability was expected due to reduced plantar input, indicating no compensation by other sensory systems. Experiment III focused on the inter- and intraday- reliability of dynamic balance responses using the Posturomed device. Generally good relative and absolute reliability were found for COP excursions. This outcome was fundamental to proceed with dynamic balance measurements using the same setup. Subsequently, effects of reduced plantar cutaneous inputs via cooling on anticipatory and compensatory balance responses (unexpected perturbations) were explored in Experiment IV. COP and EMG data were used to analyze anticipatory and compensatory balance responses. No differences in COP or EMG parameters were found for the anticipatory responses after hyper-thermia, while decreased values for compensatory balance responses were observed in response to cooling. This was interpreted as a kind of overcompensatory behavior of the central nervous system (CNS) due to more cautious behavior induced after plantar cooling. Finally, the question regarding the interaction between afferent receptors arose in Experiment V, in which the effects of reduced plantar temperatures on the Achilles tendon stretch reflex and plantar flexion were examined. Short latency responses and maximal force of plantar flexion were analyzed. Cooling resulted in decreased amplitudes of short latencies, as well as in delays in time to maximal force of plantar flexion. These findings suggest that plantar inputs participate complementarily in the Achilles stretch reflex. Collectively, the current thesis contributes to understanding how plantar receptors are involved in movement control; not only do they seem to work as independent contributors, but they also appear to interact with other afferent receptors. Furthermore, an important outcome is that the reduced plantar inputs seem to induce different alterations in the organization of CNS inputs and outputs, according to different balance tasks: quasi-static responses, anticipatory responses, and compensatory responses. For the future, the use of other methods like microneurography and electroencephalography could be helpful to gain even more understanding of afferent interactions during the control of movements. Similar protocols may also be implemented in other populations, such as elderly people or patients suffering from neurological disorders, who exhibit continued decline or degeneration of sensory receptorsDie zentrale Integration von sensorischen Informationen, die aus verschiedenen afferenten Rezeptoren zur Verfügung gestellt werden, ist erforderlich, um die menschliche Bewegung zu steuern. Obwohl die Funktion der einzelnen afferenten Rezeptoren bekannt ist, bleibt die Komplexität und Interaktivität von afferenten Information unklar, insbesondere in Szenarien, in denen die Verminderung von Informationen aus einem oder mehreren afferenten Rezeptoren eintritt. Reduzierte plantare Sensibilität wird häufig im Zusammenhang mit Haltungsinstabilität verbunden. Dies tritt häufig während des Alterns ein, bei peripheren Neuropathien und anderen neurologischen Erkrankungen, wie etwa bei der Parkinson-Krankheit. Obwohl es in den vergangen Jahren große Entwicklungen was das Verständnis afferenter Inputs gab, ist die Rolle afferenter Information bei der Bewegungskontrolle immer noch unklar. Daher ist das Ziel der vorliegenden Dissertation, den Einfluss der Beeinträchtigung der plantaren Sensibilität auf das quasi-statische und dynamische Gleichgewicht, sowie auf den Reflex der Achillessehne, zu untersuchen. Die vorliegende Dissertation ist dazu aus fünf Untersuchungen aufgebaut. Zwei Untersuchungen werden als Voruntersuchungen präsentiert, während die übrigen drei Untersuchungen auf die Kernfragen dieser Doktorarbeit gerichtet sind. Die erste Untersuchung beschäftigt sich mit der grundlegenden Fragestellung bzgl. der subjektiven Fußsensibilität (Vibrationswahrnehmung), die in zwei verschiedenen Körperpositionen gemessen wurde: Im Stehen und im Sitzen. Ergebnisse aus Untersuchung I zeigten keine Unterschiede der Vibrationswahrnehmung zwischen den beiden Körperpositionen. Daher ist es möglich, Vergleiche zwischen Daten aus plantaren Vibrationswahrnehmungstests während des Sitzens und des Stehens (z.B. bei Gleichgewichtstests) durchzuführen. In Untersuchung II wurde die Rolle afferenter Informationen plantarer Mechanorezeptoren auf das quasi-statische Gleichgewicht mittels zwei unterschiedlicher Abkühlverfahren untersucht: eine permanente Abkühlung durch eine thermische Plattform und konventionelle Eis-Pads. Es wurden der COP Gesamtweg, plantar Temperaturen und eine visuelle Analogskala (VAS) in Bezug auf subjektive Schmerzen analysiert. Untersuchung II hat gezeigt, dass eine konstante und steuerbare Abkühlung über die thermische Plattform der überlegene Ansatz in Bezug auf subjektiven Schmerz (VAS) und bzgl. des Erreichens und Erhaltens einer gewünschten Temperatur innerhalb der Messungen ist. Weiterhin wurde nur durch die Abkühlung mittels thermischer Plattform eine posturale Instabilität induziert, evident durch erhöhte COP Gesamtwege. Diese Instabilität wurde aufgrund der Beeinträchtigung der plantaren Sensibilität erwartet, was auf eine fehlende Kompensation durch andere Sinnessysteme hinzuweisen scheint. In Untersuchung III lag der Fokus auf der inter- und intra-Tag-Reliabilität dynamischer Gleichgewichtsantworten mittels des Posturomed-Trainingsgerätes. Im Allgemeinen wurden eine gute relative und absolute Reliabilität der COP Gesamtwege ermittelt. Dieses Ergebnis war von grundlegender Bedeutung, um die Nutzung des gleichen Setups für die folgenden dynamischen Gleichgewichtsmessungen (Untersuchung IV) zu ermöglichen. Anschließend wurden die Effekte einer Beeinträchtigung der plantaren Sensibilität mittels Abkühlung auf antizipatorische und kompensatorische Antworten des dynamischen Gleichgewichts (anhand unerwarteter Störungen des Gleichgewichts) in Untersuchung IV erforscht. COP und EMG Daten wurden verwendet, um die antizipatorischen und kompensatorischen Antworten des Gleichgewichts zu analysieren. Nach der Abkühlung wurden bzgl. antizipatorischer Antworten keine Unterschiede in den COP und EMG Parametern gefunden. Im Hinblick auf kompensatorische Antworten zeigten sich reduzierte COP und EMG als Reaktion auf die Abkühlung. Dies wurde wie folgt interpretiert: aufgrund eines vorsichtigen Verhaltens, ausgelöst durch die verminderten sensorischen Inputs infolge der Abkühlung, kam es zu einer Art „Überkompensierungsverhalten“ des zentralen Nervensystems (ZNS). Schließlich stellte sich die Frage der Interaktion afferenter Rezeptoren in Untersuchung V, in welcher die Effekte reduzierter plantarer Temperaturen auf den Achillessehnen-Dehnungsreflex und die Plantarflexion untersucht wurden. Kurze Latenz Antworten (short latency responses) und die maximale Kraft der Plantarflexion wurden dabei analysiert. Die Abkühlung führte zu einer verminderten Amplitude der short latency responses sowie zu Verzögerungen der Zeit bis zur maximalen Kraft der Plantarflexion. Diese Ergebnisse deuten darauf hin, dass plantare Inputs in komplementärer Weise am Achillessehnen-Dehnungsreflex beteiligt sind. Zusammenfassend lässt sich aussagen, dass die vorliegende Arbeit zum Verständnis beiträgt, wie plantare Rezeptoren an der Bewegungssteuerung beteiligt sind. Es scheint, dass diese nicht nur in unabhängiger Form zur Bewegungssteuerung beitragen, sondern dabei auch mit anderen afferenten Rezeptoren interagieren. Darüber hinaus ist ein wichtiges Resultat, dass die reduzierten plantaren Inputs scheinbar verschiedene Änderungen in der Organisation von Ein- und Ausgängen im ZNS induzieren. Dies erfolgt anhand unterschiedlicher Anforderungen an das Gleichgewicht: quasi-statische Antworten, antizipatorische Antworten und kompensatorischen Antworten. Für die Zukunft könnte die Implementierung anderer Methoden, wie Mikroneurographie und Elektroenzephalographie, hilfreich sein, um noch mehr Verständnis bezüglich afferenter Interaktionen während der Kontrolle von Bewegungen erlangen zu können. Ähnliche Protokolle könnten auch in anderen Populationen durchgeführt werden, wie ältere Menschen oder Patienten mit neurologischen Erkrankungen, die einen kontinuierlichen Rückgang oder Degenerationen sensorischer Rezeptoren zeigen
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Leach, Steve M. "Optimum control of hand-portable antennas for satellite and terrestrial mobile communications." Thesis, University of Surrey, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326810.
Повний текст джерела
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Lakshmanan, Prem Kumar. "A near optimum strategy for semipassive attitude control of large communications satellites." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25107.
Повний текст джерелаАнотація:
Effectiveness of solar radiation pressure in the three-axis attitude control of present day and next generation of large communications satellites is investigated. A simple two-flap configuration is used with optimization of the direction of the applied control moment rather than the magnitude of the weak solar radiation pressure. Simulations were carried out in the presence of varying orbital eccentricity and inclination, solar aspect angle and controller dynamics parameters. Time histories of librational response against orbital position are presented for controlled and uncontrolled conditions. The results suggest the semipassive controller to be quite effective over a wide range of system parameters and it can meet the exacting pointing accuracy demanded by large communications satellites.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
40
Rufinelli, Marco. "Optimum Damping of Beam Vibrations Using Piezoceramic Transducers." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/64936.
Повний текст джерелаАнотація:
In this thesis a piezo-electro-mechanical system, constituted of an aluminum
beam with five piezoelectric patches glued on it, each of them shunted with
an RL electrical circuit, has been numerically and experimentally
investigated, in order to determine the optimal electric tuning parameters
for vibration damping. A numerical code based upon Galerkin
weighted-residual method is developed and the complete
piezo-electro-mechanical system is designed, realized and finally tested by
a standard modal testing technique. Comparisons between different shunting
configurations of the system are given and finally the experimental data are
compared with ones obtained by the developed numerical code in order to
verify the accuracy of the latter.Master of Science
41
Cruz-Hernández, Juan Manuel. "Modeling, sensitivity analysis and control design for a tendon transmission." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23256.
Повний текст джерелаАнотація:
The modelling, analysis, and control of a tendon transmission for a haptic device is presented. A linear force-to-force model is used to study the dynamics of the transmission, to predict how certain system parameters affect the response, and how these parameters can be modified for improvements. To this end, sensitivity analysis was applied to show how the system is affected for each of its components considered in the linear model. This sensitivity analysis leads to criteria that can be used to choose the best values for the parameters to achieve a wide bandwidth and a good disturbance rejection. Nominal values of some parameters were identified with the help of a testbed representing one channel of the haptic interface. Significant nonlinearities were observed in force-to-force, force-to-velocity, and force-to-position phase plots. The open loop and closed loop responses (using a proportional, a second and a fourth order lead controllers) were then compared. The final design of the controller was done using the loopshaping technique. This controller was designed from the information about linear behavior of the plant and to reduce the nonlinearities shown in the force-to-force phase plot. The idea is to lump the memory effects of the transmission as a linear model, while the nonlinear response is assumed to be memoryless. This can actually be experimentally verified. A robust controller was designed given the range of uncertainty given by the open loop response to signals with different amplitudes. It is capable of reducing the nonlinearities seen in the open loop response to insignificant values. The controller also exhibits very good disturbance rejection and robustness. The performance of each controller is presented in terms of the closed loop Bode plot and phase plot. Experimental results are presented showing the characteristics of the controller.
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Sadri, Parissa. "HISS-dependent control of insulin sensitivity in health and disease." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ62664.pdf.
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Butler, Kevin Allan. "Effects of smoking status on punishment sensitivity and cognitive control." Thesis, University of Brighton, 2013. https://research.brighton.ac.uk/en/studentTheses/70036943-151e-4e81-a084-35c84fd246f4.
Повний текст джерелаАнотація:
A hallmark feature of addiction, including nicotine dependence, is persistent drug use despite the adverse consequences of such behaviour. This implies that there may be deficient processing of punishment in dependent individuals. However, despite growing bodies of research investigating both altered reward sensitivity and error monitoring deficits there is a paucity of empirical work investigating sensitivity to punishment in nicotine dependence. The main aim of this thesis was therefore to investigate the effects of satiation level (abstinent/satiated) and smoking history (current/former/never) on behavioural measures of punishment sensitivity. Furthermore, the related phenomenon of loss aversion (the tendency for individuals to be more sensitive to losses compared to gains) was investigated in former smokers alongside a range of self-control indices.
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Hasan, Md Mahbub. "Comparative sensitivity of Tribolium spp. to gamma irradiation throughout ontogeny." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283051.
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Blakemore, Amy. "Insulin sensitivity tools for critical care." Thesis, University of Canterbury. Mechanical Engineering, 2009. http://hdl.handle.net/10092/2606.
Повний текст джерелаАнотація:
Stress induced hyperglycaemia is prevalent in critical care. Since the landmark paper published by Van den Berghe et al. (2001) a great deal of attention has been paid to intensive insulin therapy in an ICU setting to combat the adverse effects of elevated glucose levels and poor glycaemic control. Glycaemic control protocols have been extensively developed, tested and validated within an ICU setting. However, little research has been conducted on the effects of a glycaemic
control protocol in a less acute ward setting. There are many additional challenges presented in a ward setting, such as the variation in meals and levels of activity between patients, from day to day and throughout the day.
A simple compartment model is used to describe the nature of insulin and
glucose metabolism in patients of the Cardiothoracic Ward (CTW). A stochastic
model of the fitted insulin sensitivity parameter is generated for this cohort
and validated against cohorts of similar characteristics. The stochastic model is then used to run simulations of predictive control on 7 CTW patients, which shows significantly tighter glucose control than what is obtained with regular clinical procedures. However, the rate of severe hypoglycaemia is an unacceptably high 4.2%. The greatest challenge in maintaining tight glycaemic control in
such patients is the consumption of meals at irregular times and of inconsistent quantities.
Insulin sensitivity was compared to extensive hourly clinical data of 36 ICU
patients. From this data a sepsis score of value 0-4 was generated as gold standard marker of sepsis. Comparing the sepsis score to insulin sensitivity found that insulin sensitivity provides a negative predictive diagnostic for sepsis. High insulin sensitivity of greater than Si = 8 x 10⁻⁵ L mU⁻¹ min⁻¹ rules out sepsis for the majority of patient hours and may be determined non-invasively in real-time from glycaemic control protocol data. Low insulin sensitivity is not an effective
diagnostic, as it can equally mark the presence of sepsis or other conditions.
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Capp, Alison Jane. "An electrophysiological study of sensitivity control in the vertebrate (fish) retina." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47374.
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Petrzelka, Joseph E. "Contact region fidelity, sensitivity, and control in roll-based soft lithography." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74909.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 341-349).
Soft lithography is a printing process that uses small features on an elastomeric stamp to transfer micron and sub-micron patterns to a substrate. Translating this lab scale process to a roll-based manufacturing platform allows precise control of the stamp contact region and the potential for large area, high rate surface patterning. In this manner, emerging devices can be produced economically, including flexible displays, distributed sensor networks, transparent conductors, and bio-inspired surfaces. Achieving and maintaining collapse-free contact of the soft stamp features is a necessary condition for printing. In the first part of the thesis, stamp behavior is examined at two length scales. First, microfeature collapse is examined across a range of dimensionless aspect ratios and pattern ratios to determine the collapse mode and the feature stiffness. Second, behavior of roll-mounted stamps is investigated on the macroscopic scale. The results of these analyses, simulations, and experiments show that contact is prohibitively sensitive as the feature scale shrinks to single microns or below. In the second part of the thesis, methods are developed to reduce the contact sensitivity. A compliant stamp architecture is introduced to tune the mechanical response of the stamp. Next, a new process for manufacturing cylindrical stamps is developed that removes limitations of planar stamp templates. The third part of the thesis addresses process control. A parallel kinematic stage is designed to manipulate the height and pitch of a roll over a substrate with submicron precision. A hybrid state-space / classical feedback control approach is used to achieve high bandwidth servo control in the presence of coupling and unmodeled dynamics. Using optical instrumentation, the stamp contact pattern is monitored and can be controlled using camera images as a control variable. Ultimately, a practical method of impedance control is implemented that demonstrates excellent disturbance rejection. The results of this thesis provide models for stamp behavior at the local microscale and the roll-based macroscale. These results illustrate the high sensitivity of contact to displacement disturbances in roll-based lithography, but also provide valuable design insight towards designing stamps and processing machinery that are robust to these inherent disturbances.
by Joseph Edward Petrzelka.
Ph.D.
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Hinchliffe, Benjamin Lee. "Using surface sensitivity for adjoint aerodynamic optimisation of shock control bumps." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/16163/.
Повний текст джерелаАнотація:
The purpose of this research is to use the surface sensitivity to aid the design and placement of flow control devices and to develop a new and efficient method of calculating the surface sensitivity using the mesh adjoint equations. The mesh adjoint equation provides a implification of the adjoint optimisation framework which can speed up an optimisation by removing the bottleneck of needing to calculate the mesh sensitivity. The surface sensitivity can be used as a design tool a designer to the most important regions on an aircraft surface. This thesis focusses on using shock control bumps and surface contour bumps in drag sensitive regions on transonic aerofoils and wings to reduce drag. Usually a designer has the surface pressure and streamlines to guide the device placement, however these can mislead as it is not clear which areas will have the most impact on drag reduction. The drag surface sensitivity gives a direct link between the drag coefficient and a potential change in the wing surface in the form of a derivative. This method was proved successful for reducing drag when optimisation was localised to the drag sensitive regions on the wing. A new method for calculating the surface sensitivity using the Delaunay Graph Mapping (DGM) mesh movement has been developed. This provides an explicit and efficient mapping of the mesh sensitivity to the surface senstivity. Previously, this required the solution of a large and costly linear system using a mesh movement such as Linear Elasticity (LE) to move the mesh. The DGM method is compared against analytical solutions, finite difference and the LE mesh adjoint to show that the DGM mesh adjoint will provide an accurate calculation of the gradients on the wing surface. The DGM mesh adjoint has been shown to successfully find a minima when optimising shock bumps on a 3D geometry showing that it is a robust and capable method for optimisation.
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Martinovic, Zoran N. "Sensitivity of active vibration control to structural changes and model reduction." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/53641.
Повний текст джерелаАнотація:
The analytical study presented here is concerned with by two types of sensitivity of active vibration control of large space structures (LSS). The first one required for assessing robustness, is the sensitivity of the performance and stability of the control system to changes in structure and to model reduction. The second type is the sensitivity of the optimum design of the control system to changes in the structure. This sensitivity is of interest in assessing the need for integrated structure/control design.
Three direct rate feedback (DRF) control techniques are studied for a laboratory structure which has characteristics of LSS and then compared to standard linear quadratic (LQ) control. The baseline design of each control system is obtained first and then sensitivity analysis conducted.
An uncoupled DRF control law which minimized the sum of gains subject to requirements on performance was not robust to structural changes, and small changes in the structure caused notable increase in performance compared to that of the baseline design and therefore a potential gain from simultaneous structure/control design was indicated.
Two coupled DRF techniques are proposed. A Minimum Force DRF (MF-DRF) law minimized maximum force of any actuator, while a Linear Quadratic DRF (LQ-DRF) law minimized the standard quadratic performance index for initial conditions in the shape of the first six natural modes. Both techniques guaranteed system stability. The LQ control law was found to be only slightly better than the simpler MF·DRF law in terms of the quadratic performance index and poorer than the LQ-DRF law. However the LQ control requires model reduction and was found to be sensitive to errors in that process. For example, the LQ design lost its stability when the structure was modified by adding a non-structural mass to it.
A separate experimental study was conducted simultaneously with this study to verify theoretical results. Good agreement was found between analytical results and experimental measurements for the investigated control techniques.Ph. D.
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YANG, WEI-LIN, and 楊偉霖. "Sensitivity analysis for optimal control problem and its application." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/77468261405641232026.
Повний текст джерела