Identity and power are important components of any relationship, especially one as intimate as the connection between marital partners. Social support is expected and elicited within these relationships, however most social support researchers have not incorporated sociological theoretical orientations that would provide insight into the structural components of the relationship and their impact. Using ideas derived from Identity Control Theory and Power Dependence Theory this research investigates the impact of these powerful social factors. Specifically, I hypothesize that marital partners who are similar in their identities will be better able to offer social support in conversations in which those identities are salient. I also hypothesize that partners who are similar in structural power will offer more support than those who are dissimilar.

Long bridges tend to develop large deformations under the action of intense dynamical loads such as wind or earthquakes. Unless these deformations are controlled in some fashion, the structure might suffer damage or even collapse. One possible solution to this problem is to apply external forces to the bridge through suspension cables. This work presents an active robust control scheme to suppress the vibrations caused by the vertical ground motion due to an earthquake of a cable-stayed bridge. It is proven both mathematically and through computer simulation that the active nonlinear controller is capable of reducing the amplitude of the vibrations to an arbitrarily small size. This may save the bridge structure during a strong earthquake. It is shown that the control scheme performs satisfactorily even if parts of the system fail during an earthquake. An alternative method to derive the control law using finite elements is also presented. / Graduation date: 1993

The objective of this investigation is the development of improved techniques for the estimation of robustness for dynamic systems with structured uncertainties, a problem which was approached by application of the Lyapunov direct method. This thesis considers the sign properties of the Lyapunov function derivative integrated along finite intervals of time, in place of the traditional method of the sign properties of the derivative itself. This proposed approach relaxes the sufficient conditions of stability, and is used to generate techniques for the robust design of control systems with structured perturbations. The need for such techniques has been demonstrated by recent research interest in the area of robust control design. The system considered is assumed to be nominally linear, with time-variant, nonlinear bounded perturbations. Application of the proposed technique warrants that estimates of robustness will either match or constitute an improvement upon those obtained by application of the traditional Lyapunov approach. The application of numerical procedures are used to demonstrate improvements in estimations of robustness for two-, three- and four-dimensional dynamic systems with one or more structured perturbations. The proposed numerical approaches obtain improved bounds, which are considered in the sense of their engineering aspects. To increase the accuracy of the numerical procedures, symbolic algebraic calculations are utilized. / Graduation date: 1991

El disseny d'un controlador es un procés que requereix adquirir y processar informació amb la finalitat de dissenyar un sistema de control satisfactori. A més a més és àmpliament reconegut el fet de que si s'afegeix nova informació en el procés de disseny d'un controlador, és possible millorar el funcionament del controlador obtingut. Aquesta és la filosofia existent darrere del control adaptatiu. No obstant el concepte d'informació referit al problema del disseny de reguladors, si bé està molt estes, no disposa d'una formalització clara ni unificadora degut a la mancança d'un marc conceptual. Aquesta tesi aborda el problema del disseny de controladors des d'un punt de vista de la informació requerida per aconseguir aquesta finalitat. Les aportacions de la tesi es divideixen en dues parts. En la primera part l'objectiu és caracteritzar el concepte d'informació dins del problema del disseny de controladors, així com analitzar totes les fonts d'informació disponibles. Aquest objectiu s'aconsegueix mitjançant el desenvolupament d'un marc conceptual en el qual es pot establir relacions fonamentals necessàries per augmentar la informació dels elements del problema de control. En un segon pas, aquest marc ja establert s'utilitza par analitzar i comparar les tècniques del control adaptatiu clàssic amb el control iteratiu. El marc permet comparar ambdues tècniques de disseny de controladors en funció de la gestió de la informació que cadascuna d'elles realitza, proporcionant així un punt de referència per comparar diverses maneres de gestionar la informació per al disseny de controladors. En la segona part de la tesi s'aborda el problema de la validació de la informació existent en un model. L'objectiu és ser capaç de validar un model de manera que el resultat de la validació no sigui simplement un resultat binari de "validat/invalidat", si no que es donen guies de decisió sobre com gestionar la informació dels elements del problema de control amb la finalitat d'augmentar la informació dels models. Per aconseguir aquest fi es desenvolupa l'algorisme de validació FDMV (Frequency Domain Model Validation) que permet que el resultat de la validació d'un model sigui dependent de la freqüència. D'aquest fet es conclou que un mateix model pot ser validat per a un cert rang de freqüències mentre que el mateix model pot ser invalidat per a un altre rang de freqüències diferents. Aquesta validació dependent de la freqüència permet millorar la gestió de la informació en lo referent a 1) disseny experimental per a una nova identificació, 2) selecció de l'ordre del model adequat i, 3) selecció de la amplada de banda del controlador acceptable per l'actual model. L'algorisme FDMV es mostra com una eina especialment apropiada per a ser emprada en tècniques de control iteratiu. / El diseño de un controlador es un proceso que requiere adquirir y procesar información con el fin de diseñar un sistema de control satisfactorio. Además es ampliamente reconocido el hecho de que si se añade nueva información en el proceso de diseño de un controlador, es posible mejorar el desempeño del controlador obtenido. Esta es la filosofía existente detrás del control adaptativo. Sin embargo el concepto de información referido al problema de diseño de reguladores, si bien está muy extendido, no dispone de una formalización clara ni unificada al carecer de un marco conceptual. En esta tesis se aborda el problema del diseño de controladores desde un punto de vista de la información requerida para tal fin. Las aportaciones de la tesis se dividen en dos partes. En la primera parte el objetivo es caracterizar el concepto de información cuando hablamos del problema del diseño de controladores, así como analizar todas las fuentes de información disponibles. Esto se consigue mediante el desarrollo de un marco conceptual en el cual se pueden establecer relaciones fundamentales necesarias para aumentar la información de los elementos del problema de control. En un segundo paso, dicho marco ya establecido se utiliza para analizar y comparar las técnicas del control adaptativo clásico con el control iterativo. El marco permite comparar ambas técnicas de diseño de controladores en función de la gestión de la información que cada una de ellas realiza, proporcionando así un punto de referencia para comparar diversas maneras de gestionar la información para el diseño de controladores. En la segunda parte de la tesis se aborda el problema de la validación de la información existente en un modelo. El objetivo es ser capaz de validar un modelo de manera tal que el resultado de la validación no sea simplemente un resultado binario de "validado/invalidado", si no que aporte guías de decisión sobre como gestionar la información de los elementos del problema de control con el fin de aumentar la información del modelo. Para tal fin se desarrolla el algoritmo de validación FDMV (Frequency Domain Model Validation) que permite que el resultado de la validación de un modelo sea dependiente de la frecuencia. De ello se sigue que un mismo modelo puede ser validado para cierto rango de frecuencias mientras que el mismo modelo puede ser invalidado para otro rango de frecuencias diferentes. Esta validación dependiente de la frecuencia permite mejorar la gestión de la información en lo referente al i) diseño experimental para una nueva identificación, ii) selección del orden del modelo adecuado y iii) selección del ancho de banda del controlador aceptable por el modelo a mano. El algoritmo FDMV se muestra como una herramienta especialmente apropiada para ser empleada en técnicas de control iterativo.

Many applications in robotics require faithfully following a prescribed path. Tracking controllers may not be appropriate for such a task, as there is no guarantee that the robot will stay on the path. The objective of this thesis is to develop a control design method which makes the “output” of a robot get to, and move along the prescribed path without leaving the path. We consider the class of mechanical systems, which encompasses robotics. Various techniques exist for designing pah following controllers. We base our approach on a technique called “transverse feedback linearization”. Using this technique, if feasible, we decompose the dynamics of a mechanical system into a transversal subsystem and a tangential subsystem using a coordinate and feedback transformation. The transversal subsystem is linear, time-invariant and decoupled from the tangential subsystem. Stabilizing the origin of the transversal subsystem is equivalent to stabilizing a set corresponding to the output of the mechanical system being on the desired path, thereby partly achieving the control objective. Given a mechanical system and a path, we provide conditions under which this is possible. The tangential subsystem describes all of the motions of the mechanical system, when the output is on the path. Some tangential dynamics may move the output along the path, and thereby meet the design objective. In order to move the output of the mechanical system along the path, we further decompose the tangential subsystem into a subsystem which moves the output along the path, and a subsystem which does not, if feasible, using partial feedback linearization. The subsystem which governs output motions along the path is linear, time-invariant and decoupled. The remaining tangential dynamics have no special structure. We provide conditions under which such a decomposition of the tangential dynamics is possible. We show that a five-bar robotic manipulator has dynamics which may be transversely feedback linearized, and the tangential dynamics may be partially linearized. Given a circular path, we experimentally implement our path following design, and observe that our control objective is indeed met. Inherent advantages of path following over trajectory tracking are illustrated. Standard feedback linearization of a five-bar robotic manipulator with a flexible link has been shown to fail. We show that this system is transversely feedback linearizable, and its tangential dynamics may be partially linearized, under mild restrictions. Simulations illustrate path following applied to this complex system.

This project examines attitude change between 1981 and 2001 for a population of young, well educated Canadians, employing evaluation, potency and activity (EPA) semantic differential ratings of approximately 800 social identities. This comprises my larger data set. I also employ a smaller subset of 102 social identities drawn from the larger data set to explore changes across three points in time (1981, 1995, and 2001) for 102 social identities, supplementing my analysis across two points in time (1981 and 2001) for 800 social identities. The objectives for this dissertation are: (1) to assess stability of attitudes for social identities over time; (2) to identify and describe patterns of change in identity attitudes and to connect observed changes in identity attitudes to historical events, and to social and cultural change in Canadian society; (3) to explore the extent to which identities that cluster together in EPA space define social institutions; and (4) to explore how changes in identity attitudes affect role expectations over time. Despite significant shifts in attitudes for a number of identities, approximately 80% of identity attitudes remained stable over time, confirming findings from past research that cultural sentiments are slow to change. Observed changes could be connected to social and cultural structure. Specifically, dramatic changes occurred for religious and sexual preference/orientation identities. Numerous religious identities decreased on evaluation for male respondents between 1981 and 1995 and then were restored to earlier levels by 2001. Female respondents were not as forgiving and 1995 decreases in evaluation were sustained. These changes are connected to increased secularization and earlier sexual scandals in religious institutions. Sexual preference/orientation identities increased significantly on evaluation for both males and females. However, increases for females were more dramatic and occurred across all three points in time while changes in attitudes for males occurred between 1981 and 1995 and then changed little between 1995 and 2001. These changes can be connected to numerous factors, including the increased visibility of gay/lesbian culture in mainstream media and the absence of a strong anti-gay counter movement. Although social identities clustered in interesting ways, cluster analysis was not very successful in defining social institutions. Computer simulations revealed how role and behaviour expectations change with changes in identity attitudes. For example, there is obvious increase in evaluation between 1981 and 2001 for the behavior of a police officer toward a homosexual. This dissertation concludes by addressing methodological issues such as sample size and generalizability. It is suggested that the corpus of identities should be continually updated to include identities that are emerging from pop culture. Finally, four areas of future research are suggested: (1) a continual monitoring of cultural sentiments; (2) a more detailed focus on individual social institutions; (3) a confirmation of computer predictions with qualitative interview data; and (4) identifying the implications of this research for trend analysis. Practical implications of this dissertation research include the use of computer simulations of identity-role processes in the areas of education and policy research.

Information systems development (ISD) project management involves planning, organizing resources, measuring and controlling progress against plans with an overall goal of achieving a set of project objectives, including schedule, cost, and quality. The purpose of project control is to provide an understanding of project¡¦s progress so that appropriate corrective actions can be taken when the project¡¦s performance deviates significantly from the plan. Because the management of ISD is nonroutine and difficult, it provides a classic example of the issues associated with structuring control mechanisms for complex tasks. For the rapid development of information technology and the quick change of environment, companies are increasingly outsourcing all or part of their IS activities, including IS development. Become a partnership of strategic alliance between the client and the vendor is the trend of IS outsourcing activities. The truly critical success factors associated with successful outsourcing are those associated with vendor governance. An important aspect of this governance is how the client exercise control over the vendor. Outsourced ISD projects pose unique problems that make the task of controlling them particularly challenging. This research views control broadly, in a behavioral sense. The behavioral view of control implies that the controller uses certain devices, or control mechanisms, to promote desired behavior by the controllee. These control mechanisms help implement control modes, which may broadly be divided into formal controls and informal controls. Two types of formal controls have been commonly considered in prior literature, including outcome control and behavior control. Informal controls are also of two types: clan control and self-control. This study employs control theory to establish the research model, and examines the factors influencing the choice of control modes, the dynamics of control, and evolution of portfolio of controls over the duration of outsourced ISD projects. The differences between the internal ISD and the outsourced IS projects are also examined. Drawing from the case study, it concludes that some findings from research on control of internal ISD projects apply to the outsourced context as well, but with some interesting differences¡G (1)At the choice of formal controls, there is no distinction between the internal ISD and the outsourced ISD projects. (2)At the choice of informal controls, there is obvious distinction between the internal ISD and the outsourced ISD projects. (3)In a strategic alliance context, it is expected that informal controls could be exercised in the outsourced ISD projects, as well as in the internal ISD projects. The degree of informal controls could be exercised is determined by the role expectations and the long-term cooperation between the client firms and the vendors.

Identity and power are important components of any relationship, especially one as intimate as the connection between marital partners. Social support is expected and elicited within these relationships, however most social support researchers have not incorporated sociological theoretical orientations that would provide insight into the structural components of the relationship and their impact. Using ideas derived from Identity Control Theory and Power Dependence Theory this research investigates the impact of these powerful social factors. Specifically, I hypothesize that marital partners who are similar in their identities will be better able to offer social support in conversations in which those identities are salient. I also hypothesize that partners who are similar in structural power will offer more support than those who are dissimilar.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 86-95). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2004. / Includes bibliographical references (p. 51-54).