The purpose of this study was to document the effects of applying the platform unity concept, a concept based on the principle of curriculum alignment. This principle states that the planned, the delivered, and the tested curricula are congruent. Specifically, platform unity aligns planned, domain-referenced content with appropriate test types. Mathematical formulae were created to determine numerically if planned and tested content were congruent. In addition, four other constructs were examined. They included overtesting and undertesting of course content and, effectiveness and efficiency of test item type selection. / Ph. D.

A common concern for people using computer databases is becoming "lost" within the complex hierarchy of entries. Most direct manipulation interface design guidelines suggest designers should include a feature for “undoing” user inputs (Smith and Mosier, 1986). In the case of a database, undo translates to backtracking support. The first purpose of this research was to confirm that computer-supported backtracking tools reduce navigation time over manual backtracking. The second purpose was to compare navigation times among a subset of backtracking tools. The third purpose was to determine if users prefer to use one or more backtracking tools significantly more than others. Four backtracking tools were developed by crossing two factors: History (history list vs no history list) and Level (component vs entry). History list indicates the user may view a chronological listing of nodes that have been viewed and directly select a destination node. No history list means the user must backtrack through each visited node with no shortcuts. Component indicates the backtracking tools operate only at the lowest level, or smallest definable node, of the tree-like database structure. Entry means that backtracking occurs at the higher parent node. Thus, multiple components make up an entry . In addition to the four computer backtracking tools, overall navigating and manual backtracking was done using a hierarchical Table of Contents. The tools were evaluated in an experimental, hierarchical, direct-manipulation database. Trials were conducted in the form of a multiple-choice information retrieval task. The independent variables included the backtracking tool (four-computer supported, one-manual) and the backtrack Task Length. The dependent measures included navigation time, the frequency with which the computer tool was used over manual backtracking (Table of Contents), and questionnaire responses. The results of this study provided some of the first solid support for the many guidelines that have been written recommending user recovery, or undo support. Backtracking with any of the four computer-supported tools resulted in a significantly smaller navigation time than manual backtracking using the Table of Contents. Subjects using either of the entry tools had consistent backtracking times across trials regardless of backtrack task length. When provided with a history list, subjects in the entry condition had significantly smaller navigation times than subjects in the component condition. Users did not show any differences between computer tools in rated efficiency, ease of use, or objective preference measures. / Master of Science

A systems engineering life-cycle approach is used to design the Facilities Automated Scheduling Tool (FAST) for the Facilities Branch of the ABC Company. The emphasis of the proposed design is the human factors criteria that are used to optimize the human-computer interface (HCI). The need identified by the Facilities Branch is that the current manual project tracking system takes three weeks to gather the information required to initiate a request for change (RFC). Paperwork is cumbersome, data files are difficult to locate, and the Facilities Specialists are inundated with fragmented reports filed away in cabinets that are taking up what little free space the office has left. Therefore, the requirements for the system are established, options considered, and a recommended design is achieved which will reduce the number of file cabinets by 80%, enable a project to be input into the system in fifteen minutes, and reduce the number of data input specialists from three to one, saving the company time and money. FAST is essential to the Facilities Branch for optimal efficiency and cost-effective performance. Furthermore, many different operators need the system to track their specific projects. Most of these Facilities Specialists are not "regular" computer users, therefore, user-friendliness is of critical importance. Analyzing human factors options and presenting trade-offs is of utmost importance to ensure FAST will be used properly. If the user becomes frustrated with the system, the tool will no longer be useful to the operator or the Facilities Branch. Both the hardware and software configurations of FAST are examined for user-friendliness and efficiency. The ABC Company has a service contract with IBM, where all the hardware equipment is bought. Therefore, an IBM platform is assumed for FAST. However, various screen designs and workstation arrangements are examined in order to produce a safe. comfortable, reliable, and efficient system that will save the ABC Company time and money. / Master of Science

The theory of the aperiodically damped loudspeaker system is derived and investigated in both the time and frequency domains. The advantages of the aperiodic configuration over sealed box loudspeaker systems are discussed. The aperiodically damped loudspeaker system is described by the parameters used for sealed box loudspeaker systems, with some additions. A real system is constructed which takes full advantage of aperiodic configuration, and its performance is compared with a sealed box system of the same dimensions. Complete derivations of the theory for both the sealed box and aperiodically damped systems are included, as well as methods for measuring all required parameters. / Master of Science

This project developed a process for developing and evaluating enhancements to the American Red Cross’ disaster communication system. The stimulus for this project was a statement from the American Red Cross Disaster Service staff that the present communication system was unable to meet their needs. Some proposals for altering the present system were available, but there was no established means to identify the merits and drawbacks of these proposals. A principal feature of the proposed development process is a methodology to evaluate the impact, benefit, and cost of proposed enhancements. This methodology can be used to evaluate any proposed change to the disaster communication system. The process and methodology which have been developed are adaptations of accepted systems engineering tools such as the Life Cycle, mission scenarios, and models. / Master of Science

It is well known that Fourier series of discontinuous functions converge slowly and that the derivatives of the series may not converge at all. Since modal expansion of structural response is a generalization of the Fourier series, slow convergence of modal expansion can be expected when the applied loads exhibit discontinuities in time or space. Thus, in a structure controlled by point actuators, slow convergence of derivatives of structural response with respect to system parameters can be expected. To demonstrate this, the sensitivity of the closed-loop response to structural changes is calculated for a multi-span beam with three control systems of increasing complexity that utilize point actuators. Reduced models based on the natural modes of the structure are formed and derivatives of the damping ratios of the closed-loop eigenvalues are calculated. As expected, the convergence of the derivatives of the damping ratios with increasing number of modes is slower than the convergence of the damping ratios themselves. The convergence is improved when distributed actuators replace the point actuators. When the control system is designed based on a reduced model, the damping ratios also converge slowly. In transient response problems, it is known that complementing the vibration modes with a mode representing static response to the loads can greatly improve convergence. Indeed, for the examples studied, when Ritz vectors corresponding to static responses due to unit loads at the actuators are added to the basis vectors, the convergence of the reduced-model derivatives is greatly enhanced. Also, when the control system is designed using a reduced model containing both vibration modes and Ritz vectors, its prediction of the full-model response is greatly improved. / Ph. D.

No description available.

No description available.

No description available.

A hierarchical methodology is developed for the overall design of manufacturing systems. The methodology consists of solutions to four levels of problems, namely, (1) manufacturing system selection, (2) shop loading, (3) machine loading and tool allocation, and (4) testing the feasibility of a schedule and determining strategies for the operational control of the system. Although these problem levels are developed in a hierarchical sense, they can be applied independently by assuming appropriate inputs to the problem level under consideration. The third and the fourth level problems are addressed in this research for the flexible manufacturing system. The first level of the hierarchical methodology addresses the problem of manufacturing system selection. The mathematical 4 model formulated for this problem captures the basic and integrated relationships among the systems and system components. This model provides a practical approach and a precise tool to determine an optimal mix of systems, to assign appropriate machines to each system, and to select the best material handling system for each system to best suit long-term production requirements at minimum costs. The second level of the hierarchical methodology addresses the shop loading problem. A mathematical model is developed for partitioning parts among the manufacturing systems selected at the first level to minimize total operating costs. For the third level problem, a mathematical model is formulated to obtain routings of parts through an FMS and to assign appropriate cutting tools to each machine in the system to minimize total machining cost. For the fourth level problem, a simulation model is developed for testing the feasibility of the solution obtained at the third level. It also helps to determine strategies for the operational control of the system. The computational experience with the mathematical models is presented using the MPSX-MIP/370 package. Sensitivity analysis is also performed to further understand system behavior under various operating conditions. Several new findings of the research are reported. Because of the special structure of the mathematical models, a computational refinement for their solution is also proposed based on Lagrangian relaxation. / Ph. D.