En este trabajo se presenta, por medio del procedimiento sistemático de selección, definición y adecuación de estrategias generales del control no--lineal, seis diferentes algoritmos propuestos que permiten efectuar el análisis y diseño del control retroalimentado para la regulación de los circuitos convertidores DC--DC, y sus modelos derivados, atendiendo a sus características intrínsecas de estructuras dinámicas no--lineales, con parámetros de valores inciertos y además de presentar, respuesta de fase no--mínima en la regulación directa del voltaje de salida. Proceso que dio como resultado diversos aportes teóricos en la línea de investigación de los convertidores DC--DC, y del control no--lineal.Al realizar al análisis del sistema y diseño del control, de los modelos promedio obtenidos vía PWM (ver capítulo II), existe un aporte con las siguientes estrategias adaptables en línea: Primero, para la regulación directa del voltaje de salida, se combina el método del vector sobreparametrizado, con la propuesta necesaria de realizar el desarrollo de reinicios en el controlador sobre un ajuste "seudo--deslizante". Segundo, se efectúa la regulación indirecta del voltaje de salida con el método de diseño del control denominado "salto atrás" (backstepping), aportando una nueva Forma Canónica de control generada a partir del sistema transformado de imperfecciones en variables de fase generalizadas, definida al linealizar el sistema. Ambas estrategias permiten el ajuste de los parámetros constantes pero inciertos en el modelo del controlador, con la característica de estar desarrollados sobre la base de una linealización nominalmente exacta.Igualmente se analiza, demuestra y se aporta el hecho que los modelos de estado promedio, o modelados de frecuencia de conmutación infinita, de los circuitos convertidores de corriente continua, coinciden con los que se obtienen en este trabajo con técnicas que describen a los sistemas Euler--Lagrange. A partir de estos modelos se aporta una metodología para llevar ha cabo la regulación indirecta del voltaje de salida en los circuitos convertidores. Posteriormente, nuevamente existe una aportación al realizar la estrategia de diseño de controladores adaptativos basados en pasividad he inclusive se extiende la metodología para proponer un algoritmo de control adaptable que solvente la estabilización en una versión de tres convertidores "boost" en cascada. Ambas estrategias aprovechan las restricciones físicas del sistema, y en particular sus propiedades energéticas. Alternativamente se innova al analizar y diseñar el sistema de control para la estabilización y seguimiento de señales de los convertidores derivados, sobre la base de modelos en tiempo discreto sustentados mediante una discretización exacta de la corriente muestreada en el inductor. / A variety of nonlinear feedback controllers, or duty ratio synthesizers, they are derived for the stabilization and reference signal tracking problems, strategies of regulation based in the stabilization of the average input current via the Pulse Width Modulation (PWM), in Dc to Dc power supplies, of the buck, boost and buck-boost types. First contribution, is that the adaptive controllers designed are Euler_Lagrange systems, and they correspond reasonably to a set of average Euler_Lagrange parameters. This procedure, generate useful connections of the associated pasivity based controllers with those of the differential flatness and sliding mode controllers. The second contribution, rather different a adaptive feedback strategy is adopted by resorting to an approach inspired by adaptive backstepping controller design methodology. Finally an exact nonlinear model in discrete time is derived for the dc to dc converters, and stabilization problem are solved on the basis of the steady state considerations about the input current "ripple". Through computer simulations, all of the feedback controllers proposed, they showed robustness with respect to unmodelled stochastic perturbation inputs affecting the value of the external voltage source.

by Thomas M. Stoker. / Bibliography: p. 25.

Pierre A. Humblet. / "May 1982" / Bibliography: leaf 5. / "Contract NSF-ECS -79-19880"

[No Abstract Submitted] / Arts, Faculty of / Asian Studies, Department of / Graduate

La asignación de los conductores es la cuarta y última fase de las cuatro etapas en que se suele dividir el complejo problema de la organización de servicios en una empresa de transporte terrestre regular.Se encuadra dentro de lo que se conoce como problema de rostering ya que se concreta en la elaboración de turnos de trabajo rotativo.Así como las tres etapas que preceden al rostering son problemas ampliamente estudiados y mecanizados en la mayor parte de las grandes compañías de trasporte, el problema de rostering plantea peculiaridades debidas a los usos de cada país y a los convenios laborales de cada empresa que hace prácticamente imposible una solución universal.La tesis presenta un acercamiento a los requisitos impuestos en algunas de las principales compañías españolas y ratifica este hecho mediante la constatación de que existen restricciones no sólo distintas sino contradictorias entre compañías.En muchos casos las restricciones impuestas son fruto de unos derechos adquiridos históricamente y en consecuencia difíciles de cambiar, cabe no obstante preguntarse si es posible mejorar la asignación que se está haciendo actualmente sin violar ninguno de los requisitos impuestos. Como respuesta, el presente trabajo plantea el cómo mejorar una situación concreta, para ello elabora un procedimiento que apoyado en técnicas de programación lineal y una heurística greedy mejora la actual asignación notablemente.Por último plantea un problema genérico donde sólo se imponen criterios de equidad en el sentido de tratar de buscar aquellas soluciones que mejor repartan la carga de trabajo y los días libres. Para resolverlo aporta un nuevo procedimiento que se divide en dos fases: construcción de patrones y construcción de listas de tareas.En la construcción de los patrones se exige que estos sean de ciclo corto, lo cual lleva a la innovación de un procedimiento que concretado en dos estrategias alternativas modifica de forma dinámica un programa lineal entero y va presentando las distintas soluciones o patrones de ciclo corto que cubren perfectamente la demanda de conductores solicitada.La elaboración de listas de tareas se aborda y resuelve satisfactoriamente mediante una heurística GRASP, la cual plantea una secuencia de programas lineales mixtos que dan la cota inferior de las asignaciones planteadas, con dicha información se van construyendo las distintas soluciones a partir de las cuales, posteriormente se lleva a cabo la búsqueda local.Se han procesado ejemplos con datos reales facilitados por algunas compañías y los resultados obtenidos reducen espectacularmente el desequilibrio observado en la carga laboral actual entre conductores. / The complex problem of assigning duties to public transport drivers is the fourth and last phase in which the problem is usually divided.It is a scheduling problem well known in the business world, due to the fact that crews work in rotating shifts.The three phases that precede the above mentioned problem are widely studied and mechanized by the majority of the large transport companies. However, the rostering problem is complicated by each country's use of this phase and to the labour agreements of each company. It makes a universal solution practically impossible.This thesis presents an approach to the requirements imposed by some of the main Spanish companies. It confirms this fact by establishing that distinct and contradictory restrictions exist among companies.In many cases the imposed restrictions are the result of historically acquired rights and are difficult to change. Nevertheless, it is feasible to improve the assignment without violating any of the imposed requirements. In short the present thesis raises the question of how to improve the situation. It details a procedure that is supported in lineal programming techniques and a greedy heuristic.Finally the thesis presents a general problem where only criteria of equity are imposed in the sense of seeking solutions that better distribute the workload and the days-off. Seeking to solve the problem has led to a new procedure that is divided into two phases: constructions of patterns and roster construction.The construction of the patterns requires short cycles, leading to an innovation that summarizes two alternative strategies that dynamically modify an Integer lineal program and displays the different solutions, or short cycle patterns that cover perfectly the drivers' demands.The roster elaboration is approached and solved satisfactorily by means of a GRASP algorithm, which raises a mixed lineal programs sequence that give the lower band of the assignments presented. With this information one arrives at different solutions from which the local search is carried out.Examples with real data have been processed, the data coming from existing companies. The results spectacularly reduce the differences observed in the present driver workload distribution.

No description available.

No description available.

En aquesta tesi, presentem una solució per a dos problemes rellevants en la teoria de control: el problema del cost quadràtic garantit i el problema del control H∞, per a un cert tipus de sistemes. Considerem els sistemes interconnectats lineals amb incerteses, sota la presència de fallades en els actuadors, i dissenyem controls descentralitzats que a més a més d'assegurar estabilitat, resolen aquests dos problemes. Treballem amb tres models diferents d'incerteses: incerteses normades o acotades, incerteses definides sobre un politop i incerteses que segueixen el model multiconvex. El model de fiabilitat emprat permet plantejar-se tant una fallada total en l'actuador com una fallada parcial. Els dos problemes tractats són:· Problema del control RGC. Sintetitzar el control fiable sota fallada en els actuadors, que assegura estabilitat i garanteix un cert nivell de rendiment o de cost, calculant una cota mínima per a la funció de cost.· Problema del control robust. Dissenyar el control que assegura estabilitat interna sota pertorbacions en el sistema, obtenint una cota per a la relació entre la pertorbació i la sortida controlable. Es considera la norma H∞ del sistema, que representa l'increment màxim en energia, entre l'entrada i la sortida del sistema..A l'hora de dissenyar ambdos controls, utilitzem les tècniques donades per les inequacions lineals matricials (LMI), que permeten una fàcil implementació numèrica. Així doncs, a part de tractar els problemes de la llei RGC i del control robust, hem determinat una relació general entre inequacions matricials lineals i no lineals, que permet obtenir caracteritzacions LMI per a un gran ventall de problemes de teoria de control. Les LMI que hem obtingut separen les dades del problema i les variables de disseny, permetent una resolució menys restrictiva. En particular, faciliten l'ús de funcions de Lyapunov paramètriques que asseguren l'estabilitat del sistema quan una funció no paramètrica no arriba a fer-ho. La formulació per mitjà de les tècniques LMI ens ha permès obtenir implementacions numèriques efectives, així com relaxacions en les condicions d'estabilitat. En el cas del problema del control RGC, trobem que quan es consideren fallades en el sistema, el model d'incerteses es veu reduït en certa manera, perdent també llibertat en la definició de la funció de cost. Un cop sintetitzat el control RGC, presentem dues maneres que permeten obtenir una cota òptima del cost garantit, així com treure'n la dependència respecte les condicions inicials. Hem dut a terme exemples numèrics que mostren l'eficiència dels mètodes enunciats, tractant els models d'incerteses normat i politòpic. Els resultats s'han obtingut usant el Toolbox LMI Control del programa Matlab.El segon problema que ens plantejem és el del control estàtic realimentat per l'estat, tal que la norma H∞ del sistema es troba acotada. Aquest fet assegura que l'efecte de pertorbacions en el sistema està dins de marges desitjats. A més a més, la síntesi obtinguda és independent del model de incerteses i, en el cas dels models normat i politòpic, hem obtingut una caracterització LMI. També fem un breu estudi del control robust realimentat per la sortida, obtenint una caracterització en termes LMI, en el cas que no se suposin errors en la medició de la sortida. / This thesis presents a design of a reliable decentralized state feedback control for a class of uncertain interconnected systems. We present a solution for two outstanding problems in the control theory: the problem of the guaranteed quadratic cost control and the H∞ problem. We have designed decentralized controls that besides assuring stability, they solve these two problems. We have considered three uncertainty models: born-normed model, polytopic model and multiconvex model. A model of failures in actuators is adopted which considers outages or partial degradation in independent actuators. The two treated problems are: · RGC Control. This problem is related to the decentralized reliable guaranteed cost control problem for interconnected systems. The presented reliable control shows that the admission of control failures imposes some restriction in the control weighting matrices in the performance criterion. Thus the designer can take some trade-off between control performance and admitted reliability.· Robust Control. The control problem considered is to design feedback controller, such that the closed loop structure is stable and has a specified performance. In the standard H problem, stability means internal stability and the performance is taken to be the H norm of the transfer function from the exogenous inputs and the regulators outputs. An estimation of worst-case H norm is required. A key point in the control design has been the formulation of a new linear matrix inequality (LMI) characterization, which uses parameter-dependent Lyapunov functions and slack variables. The obtained LMI separate the unknown variables from the system parameter data, which smoothes the numerical solution. This characterization can be useful for different classes of problems, such as guaranteed cost control, H2 or H∞ control design.We use this type of LMI to proof that the proposed decentralized control scheme guarantees the quadratic stability and a cost bound, for RGC control problem, and a H∞ norm bound for a robust control problem, for a class of failure model which considers outage or partial degradation of any independent specific actuator. We make this for the three uncertainties models. A numerical example has been included to illustrate the proposed decentralized control approach. Computations have been made by using standard Matlab's LMI Control Toolbox.

The most common decisions to be taken in the design of logistic systems are related to the location of facilities and the management of vehicle fleets.In this thesis, we study three of the optimization problems arising around this kind of decisions; namely the LRP, the SGAP and the SLRP. The first problem analyzed in this work is a capacitated LRP with one single uncapacitated vehicle at each open plant. To model this problem we resort to an auxiliary network that allows us to represent feasible solutions as families of paths satisfying a series of side constraints.The solutions of a reinforced LP relaxation of this model are used as the basis of a rounding heuristic designed to build feasible solutions of the problem. Those solutions are then improved with a TS heuristic.Two lower bounds, distinct from that obtained with the LP relaxation of the model, are proposed for this problem. The first one is obtained by bound ing separately the two different parts of the cost of any feasible solution, namely the fixed costs for opening plants and the route costs. The second lower bound is the result of applying CG to the Lagrangian dual obtained by dualizing the assignment constraints. The pricing problem obtained from our formulation is an ESPPRC. The complexity of this problem, and the fact that optimality of the obtained solutions is not always necessary, have motivated us to develope a simple heuristic for it.The computational experiences show a very good behavior of the TS procedure both, for the computational effort required and the quality of the solutions. The first lower bound proposed gives satisfactory results in reasonable amounts of time. In the case of the CG approach, results are very encouraging. In some of the tested instances the program terminated because of the CPU time limit specification, before succeeding to find a valid lower bound.In those instances, the algorithm was always stalled in the exact resolution of an ESPPRC. The difficulties encountered to solve this problem represent a limitation of this approach and suggest the future study of alternative solution methods. In spite of this limitation, in a high proportion of the instances the algorithm succeeded, and the final gap between the upper and the lower bound was always 0. The success in these instances is partially due to the use of our heuristic to generate new columns whenever this is possible.The second problem studied in this thesis is a SGAP. In this assignment problem the jobs are interpreted as customers that can request a service with a given probability, and each agent can serve a limited number of customers. This uncertainty about the presence of each customer is represented by modelling the demands of the customers as Bernoulli distributed independent random variables. The problem consists of finding an a priori assignment of customers to agents. Once the actual requests for service are known, an adaptive action is taken to tackle violations of the capacity constraints. On the one hand, part of the customers assigned to overloaded agents can be reassigned. On the other hand, some of the service requests can be disregarded. Different penalties for reassignment and for unattended service requests are pre-specified. The problem is formulated as a recourse model, where the recourse function gives the expected penalties for reassignments and unattended service requests.Since this recourse function is defined as the expected value of an integer programming recourse model, it does not have the regularity properties characteristic of those defined by linear recourse models. To overcome the difficulties caused by this, we construct a convex approximation of the recourse function that is tight in all feasible points. Moreover, as illustrated in the computational experiences, the use of this approximation reduces the computational effort required to evaluate the recourse function is some orders of magnitude. The convex approximation of the recourse function allows us to adapt the well-known L-shaped method to our problem. Integrality of the first stage variables is tackled in three different ways, giving raise to three versions of the algorithm. The difference among them resides in the hierarchy between the branching and the addition of violated cuts. On the one hand, we present a version where cuts are only added when integer solutions are found. On the other hand, a version is proposed where branching is only performed when no more violated cuts can be identified. The remaining version is designed as a tradeoff of these two; at each node of the search tree, new optimality cuts are added, if needed, and branching is performed if the solution at hand is fractional. Computational experiences point out this last version as the best of the three, since the efforts devoted to obtain a rich approximation of the recourse function and to achieve integrality are more balanced.We have also derived both, lower and upper bounds for this specific SGAP. Upper bounds are obtained from three simple heuristics. All them are based on solving deterministic approximations of the SGAP and provide good quality solutions in small amounts of CPU time. A lower bound is derived from a family of linear stochastic subproblems. Althoug in some of the tested instances the gap between the bounds exceeded the 30%, in the general case we obtained small gaps.One of the heuristics was used in the exact algorithm to provide it with a good upper bound. The lower bound is also used in the three versions of the algorithm, as the basis of some of the optimality cuts and also to identify optimal solutions. The quality of these bounds is one of the factors that explain the success of the exact algorithm.The last problem studied in this thesis is a SLRP. The stochasticity considered here is of the same type as that considered for the SGAP. Again, customers may request a service with a given probability and this is modeled by introducing Bernoulli random variables to represent the demands. A two stage model is proposed for this problem. In a first stage, a set of plants to open has to be chosen together with a family of disjoint routes (one rooted at each open plant) that visit all the customers. In the second stage, once all the demands become available, the actual routes have to be designed. For plants whose number of service requests does not exceed the capacity, the actual route is derived from that designed a priori by skipping customers with no demand. When the requests for service allocated to a plant exceed its capacity, a subset of them is randomly chosen to be served, and they are visited in the order defined by the a priori route.Penalties are paid for the unattended service requests. The expected total cost of the actual routes and the expected penalties for unserviced customers are contained in the recourse function.We present a two phase heuristic to solve this problem. In the first phase, a series of subproblems are sequentially solved to build an initial solution. In the second phase, this solution is successively improved using LS. This improving phase requires a high number of evaluations of the recourse function. Although we have developed an analytical expression for this recourse function, the computational effort required for its evaluation is considerable due to its combinatorial nature. For this reason, we approximate it with a simpler auxiliary function that has allowed us to obtain solutions in small computational times.We also propose a lower bound obtained from bounding different parts of the objective function independently. Unfortunately, we only could find reasonable bounds for the sum of fixed costs for opening the plants plus the expected penalty paid for unserviced customers. Further research is intended to improve the bounding of the expected total cost of the routes.The evaluation of the quality of the solutions obtained with our heuristic is not easy due to the lack of a tight global lower bound. However, the partial bound on the costs relative to the plants allows to conclude that the heuristic makes in general a good choice of the set of plants. As for the allocation of customers to plants and the design of the routes we can only evaluate the evolution along the search. In the computational experiences reported it can be seen that this evolution is satisfactory.

This thesis is an examination of Mulla Hadi Sabzawari's commentary (1797--1878 or 1881) on the Mathnawi of Jalal al-Din Rumi (d. 1273), entitled Sharh&dotbelow;-i Asrar-i Mathnawi. The purpose of this study is to analyze Sabzawari's approach and investigate how this synthesizer of the philosophy of Mulla S&dotbelow;adra and Suhrawardi interprets Rumi's message. Moreover, I will assess the details of his arguments and philosophical interpretations of Rumi's verses. Chapter one is a brief introduction to Rumi's biography and his works as well as a review of the commentary tradition on his Mathnawi. In chapter two a full account of Sabzawari's life, including a partial translation of his autobiography and a complete list of his writings, will be offered. In chapter three, I provide my translation of Sabzawari's Arabic preface to his commentary on Rumi, which is followed by a critical analysis of his comments on the Mathnawi. Finally, chapter four is dedicated to a comparative analysis between Sabzawari's commentary and that of another Iranian commentator, Furuzanfar's (d. 1970) Sharh&dotbelow;-i Mathnawi-i Sharif. It contains a parallel reading and examination of the two commentators' views on the subject of the rational soul, which is manifested in Rumi's language through the allegory of "the Reed" ( nay).