Interest in large flexible space structures has grown considerably over the last decade. These distributed parameter systems exhibit vibration characteristics such as low, closely spaced natural frequencies and light damping, which, when coupled with the stringent pointing accuracy and vibration control requirements imposed on these systems, bring about interesting control problems. Addressing these problems has called for the use of active vibration control. Up to now, two of the most popular means for active vibration control of large space structures have been proof mass and reaction wheel actuators. These actuators are inertial-type actuators in that they operate by applying forces or moments to masses whose reaction forces, imposed on the structure, act to dampen the vibrations of the structure. A new class of actuators, variable geometry trusses (VGT's), has been recently introduced. These actuators are actually built into the structure, and they operate by varying their link lengths to apply forces to the structure or to change the shape of the structure itself. This study compared the effectiveness of four actuators in controlling the planar vibrations of a cantilevered truss-beam. The actuators chosen for the study were a proof mass actuator, a reaction wheel actuator, and two VGT's, the planar truss actuator, and the planar truss proof mass actuator (a combination VGT/inertial type actuator). Numerical simulations of each beam/actuator system were performed in response to initial condition inputs. A full-state, LQR optimal feedback control law was used with each system. These simulations provided information such as time response of the closed-loop system, damping provided to the beam, and power required by each actuator. This information can be used to determine the "best" actuator for a given purpose. The results of these simulations show that the VGT's are preferable in terms of damping added to the beam. The proof mass actuator is more efficient as far as power required to do the control, however, the efficiencies for all actuators are very similar. / Master of Science

The thesis is an investigation into the discipline of architecture. A building project serves as a tool in this investigation. The building project uses frame and skin elements to study the means of articulating a wall. Hierarchy, urban debris and scale relationships control this articulation. The design intentions are rooted in an understanding of architecture as the stage for the life of the city. / Master of Architecture

This paper investigates the development, design and modeling of a human spine-inspired seismic lateral force resisting system. The overall goal is to create a design for a lateral force resisting system that reflects human spine behavior that is both practical and effective. The first phase of this project involved a literature review of the human spine and rocking structural systems. The goal of this phase was to identify concepts from the spine that could be transferred to a lateral force resisting system. The second phase involved creating a 3-dimensional model of the lumbar region of the spine in SAP2000 and using it to examine concepts that could be transferred to a lateral force resisting system. The third phase consisted of creating possible system designs using concepts and principles identified through phases one and two and identifying a final system design. The last phase involved modeling the final lateral force resisting system design in SAP2000, validating the model and testing the design's effectiveness. This paper shows that this system is a viable option to prevent permanent structural damage in buildings during a seismic event. / Master of Science

This thesis project is an investigation of both heavy timber construction and a means to create a retreat away from the chaos of modern life. This culminated in a porch outside of downtown Austin, Texas. The program began with an entrance foyer, kitchen, wine cellar, a humidor, a library, a bar, a locker room, restrooms, and storage. The form became a long, gradually curving hallway responding to the shape of the island. Rooms expand off of the hallway at both the beginning and the end. A heavy timber truss was designed so that it could be adapted to accommodate expansion for rooms, site constraints, and programmatic needs. Special attention was paid to the details of the retreat such as the connections needed to assemble the heavy timber truss and the handrails. The project conveys a strong connection with the site it is situated on. / Master of Architecture

Ever since the advent of the Moment-Distribution procedure (1) for analyzing continuous frames, it has been possible to solve many problems conveniently which previously had required laborious solutions. Indeed, the current literature of the engineering profession finds the Cross method being adopted in new fields and being applied to new problems. The classical methods of analysis, while still retaining some measure of their former utility, are being superseded by this and other methods involving less time and labor. Yet, even with this new impetus to the field of structural analysis, the rigid space frame has received far less attention than seems justified. Here is a class of structure devoid of practically any analytical investigation and even less experimental research. The desired characteristic of all current designs has been continuity, and yet there exists this paradoxical neglect of the third dimension, without which all structures would be non-existent. The reasons for this apparent indifference are not difficult to ascertain. Practicing engineers are practical men and as such require reasonably accurate results, obtained with a minimum of effort. Economy has dictated that refinements of analysis be saved for the classroom. A two-plane analysis is generally substituted for the more complex three-dimensional case. The write feels that the interaction of members in different planes of certain structures may be quite important in some cases and that a complete, convenient analysis is justified to determine the extent of such action. / Master of Science

According to the Federal Communications Commission's rules and recommendations set forth for the 3.5 GHz Citizens Broadband Radio Service, a three-tiered structure shall govern the newly established shared wireless band. The three tiers are comprised of three different levels of spectrum access; Incumbent Access, Priority Access and General Authorized Access. In accordance and fulfillment with this dynamic spectrum access framework, we present the inclusion of Priority Access tier into a two-tiered privacy-preserving ESC-based dynamic spectrum access system. / Master of Science / With the development of wireless communication technologies, the number of wireless communication reliant applications has been increasing. Most of these applications require dedicated spectrum frequencies as communication channels. As such, the radio frequency spectrum, utilized and allocated for these wireless applications, is depleting. This problem can be alleviated by adopting dynamic spectrum access schemes. The current static spectrum allocation scheme assigns designated spectrum frequencies to specific users. This static frequency management approach leads to inefficient frequency utilization as the occupation of frequency channels may vary depending upon time periods. Dynamic spectrum access schemes allow unlicensed users opportunistic access to vacant spectrum spaces. Thus, the adoption of these spectrum sharing schemes will increase the efficiency of spectrum utilization, and slow down the spectrum depletion. However, the design and implementation of these schemes face different challenges. These spectrum sharing systems need to guarantee the privacy of the involved parties while maintaining specific functionalities required and recommended by the Federal Communications Commission. In this thesis, we present the inclusion of a three-tiered frame, approved by the Federal Communications Commission, into a privacy-preserving dynamic spectrum system.

The control problem of a large-order flexible system in the form of a beam-lattice is presented using the Independent Modal-Space Control (IMSC) method. The method is based on a transformation of the system equations of motion to modal space, yielding internally independent modal equations of motion. The control laws are designed in the modal space, permitting independent control of each mode, providing complete decoupling of the equations of motion. Linear optimal control with quadratic performance index is designed to control the response of the elastic as well as the rigid body modes, using the IMSC method. Actuators placement is of fundamental importance in the control of two-dimensional domains if IMSC is used. A method is presented as to the selection of actuators configuration in order to avoid singularity in the mode participation matrix, guaranteeing system controllability. The minimum-fuel problem is a very important one in the design of various space structures. Solution of the minimum-fuel problem is feasible in a coupled form for a fourth order system at most, but will be of insurmountable computational difficulty in the control of a flexible structure, since the model of such system will require a large number of degrees of freedom. A reformulation of the problem in the framework of "Modal Minimum-Fuel Problem" is presented, using the IMSC method. By this method, the complexity inherent in a high-order system is reduced, thus treatment of the coupled high-order system is avoided. Numerical examples for linear optimal control, with quadratic performance index, as well as for the minimum-fuel problem, are presented. / Ph. D.

There are many forces at work in a design process. Each element of a design sketch reacts to ones before and after it. As a designer, one must be able to look at each individually and as part of the whole. In addition, the ideals and experiences brought to a project works its magic as well. It is the tension and the balance between the elements and ideals that create architecture. With a Bed and Breakfast as a project vehicle, the connection to the site, the relationship between public and private areas, and how the materials and structure form spaces were studied. These considerations led to a process of discovery and the challenge to weave the site, structure, and materials in a cohesive design. / Master of Architecture

This study examined attitudes and behavioral responses to a social marketing campaign's video messages. Independent variables in the study were the regulatory framing of the campaign message, personal involvement, and collective efficacy. Results revealed main effects of both collective efficacy and personal involvement on attitude toward the brand, attitude toward the issues, and behavioral intentions. Significant interactions between collective efficacy and the regulatory frame of the video were found to affect the dependent variables. Gender was also found to significantly moderate the findings. Theoretical implications and practical implications are discussed. / Master of Arts

Motivated by the example of the tangent bundle of a stratified space, which is no longer a vector bundle, we begin the construction of a general theory of smooth stratified vector bundles. We show that one can construct a frame bundle of a smooth stratified vector bundle in a canonical way, but that there are substantial obstructions to constructing an orthonormal frame bundle. / Master of Science / Smooth manifolds are the natural class of spaces on which we can perform the normal operations of calculus. There have been many efforts to generalize the class of spaces on which one can perform these operations. One possible class are stratified spaces, which are spaces that are built out of smooth manifolds in sufficiently nice ways. Spaces such as vector bundles and their frame bundles play a central role in the smooth manifold theory, and here we begin the development of the appropriate corresponding theory for stratified spaces.