Clothing plays an important part in establishing and maintaining one's self worth. Maternity clothing is especially important: to the pregnant woman in maintaining her self-worth and in preparing for the new role as a mother. The maternity wear apparel industry caters to the average-size customer. very often it is difficult or impossible to acquire maternity clothing to fit the small or the large-size maternity wear customer. The purpose of this study was to determine the effects of self-reported dress size category on self-worth, body cathexis, and satisfaction with available selection of maternity clothing for pregnant females. / Ph. D.

In 1882, the United States Geological Survey began its National Mappping Program designed to map the nation using a series of several thousand topographic quadrangles. Since that date, the program and the maps themselves have undergone many changes due mainly to technological advances in mapping methods. The use of data collected from historic U.S.G.S. topographic maps in modem day applications necessitates a general knowledge of the potentials and limitations of these data. This study compares representations of terrain features on historic maps compiled using plane table methods with the same features as represented on more accurate modem maps compiled using photogrammetry. Using the modem map as a standard, errors in the old maps were identified and defined using statistical procedures. Measures of closed contour lines recorded the angularity of the line, the length of the line, the area within the contour, the shape of the feature and spatial relationships between contour pairs. The analysis attempts to relate errors to these geometric components of contour lines and to predict the occurrence of error. Due to practices of smoothing and generalization of contour lines in plane table surveys, measures of both angularity and shape were significantly different between older and newer maps. Systematic errors, a consistent displacement of contour lines in a similar direction, were also identified on the historic maps. Based on these results, several suggestions for continuation of the research are given. / Master of Science

Many situations arise in engineering where it is desired to model a system of complicated input and output variables. However, analytical difficulties arise when these systems exhibit nonlinear behavior. Neural networks have proven useful for such applications because they are able to model complicated nonlinear systems through exposure to a database including input parameters and the desired outputs. One such complicated system consists of the unknown relationships between flight variables and structural loads on helicopters. The development of an accurate neural network based model would allow indirect monitoring of these loads so that fatigue-damaged components could be replaced according to load history. In this thesis, an extensive database of real-time flight records has been effectively used to teach a multilayer feedforward artificial neural network nonlinear relationships between common flight variables and the resulting component loads. The trained network predicts time-varying mean and oscillatory load records corresponding to flight variable histories. Component loads in both the fixed and rotating systems of a military helicopter have been resolved over a variety of standard maneuvers. Predictions under the present conditions are on the order of 90 to 100% accurate. Although the range of maneuvers presently considered is rather limited in comparison to the total helicopter flight spectrum, the present results justify further pursuit of this neural network application. / Master of Science

Dynamic compression system response is a major concern in the operability of aircraft gas turbine engines. Computer models have been developed to predict compressor response to changing operating conditions. These models require a knowledge of the steady state operating characteristics as inputs, which limits the ability to use them as predicting tools. The full range of dynamic axial flow compressor operation spans forward and reversed flow conditions. A model for predicting the wide flow range characteristics of axial flow compressor stages has been developed and a parametric study of the effect of changing design variables on steady state performance has been conducted. This model was applied to a 3-stage, low speed compressor with very favorable results and to a 10-stage, high speed compressor with mixed results. Conclusions were made regarding the inception of stalling and the effects associated with operating a stage in a multistage environment. It was also concluded that there are operating points of an isolated compressor stage that are not attainable when that stage is operated in a multi-stage environment. A stage located in a multi-stage environment can also operate at points which cannot be reached when the stage is operated in isolation. / Master of Science

Extensive hot-wire measurements were conducted in an incompressible turbulent flow around a wing-body junction. The measurements were performed adjacent to the body and up to 11.56 chord lengths downstream of the body. The junction wake flow entered an adverse pressure gradient region approximately 6 chord lengths downstream. This region's geometry approximated the aft portion of an aircraft fuselage or a submersible's hull. The body geometry was formed by joining a 3:2 elliptic nose to a NACA 0020 tail section at their respective maximum thickness locations. The author's measurements were taken with approach flow conditions of Reθ = 6,300, and δ/T = .513, where T is the maximum body thickness. The results clearly show the characteristic horseshoe vortex flow structure. The vortex flow structure is elliptically shaped, with â (W)/â Y forming the primary component of streamwise vorticity. Near wall measurements show a thin layer of highly concentrated vorticity, underneath and opposite in sign to the primary vortex, which is created by the wall no-slip condition. The development of the flow distortions and associated vorticity distributions are highly dependent on the geometry-induced pressure gradients and resulting flow skewing directions. A quantity known as the "distortion function" was used to separate the distortive effects of the secondary flow from those of the body and the local "2-D" boundary layer. The distortion function revealed that the adverse pressure gradient flow distortions grew primarily because of the increasing boundary layer thickness. The author's results were compared to several other data sets obtained using the same body shape, enabling the determination of the approach boundary layer effects. The primary secondary flow structure was found to scale on T in the vertical and cross-stream directions, revealing that the juncture flow is driven by the appendage geometry and associated pressure gradients. A parameter known as the momentum deficit factor (MDF = (ReÏ ) 2 (θ/T) was found to correlate the observed trends in mean flow distortion magnitudes and vorticity distribution. Variations in flow skewing were observed to be comparable to changes in MDF, suggesting that this flow parameter changes the effective skewing magnitudes around a wing-body junction. Mean flow distortions were found to increase with decreasing values of MDF. A numerical study was also performed to gain additional insights into the effects of appendage nose geometry. The velocity distributions around approximately 30 different appendage cross-sections were estimated using 2-D potential flow calculations. A correlation was found between the appendage nose bluntness and the average vortex stretching rate, and also between the invisicid velocity distribution and an experimentally determined non-dimensional circulation estimate. / Master of Science

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No description available.

This thesis generalizes the concept of internal feedback loop modeling, due to Tahk and Speyer, to arrive at two new LQG-based methods of parameter robust control. One component of the robustness procedure, common to both methods, is the application of an auxiliary cost functional penalty to desensitize the system to variations in selected parameters of the state-space model. The other component consists of the formulation of a fictitious noise model to accommodate the effect of these parameter variations. The "frequency-domain method" utilizes knowledge of the system dynamics to create a frequency-shaped noise model with a power spectrum that approximates the frequency content of unknown error signals in the system due to parameter uncertainties. This design method requires augmentation of additional dynamics to the plant, which results in higher-dimensional full-order controllers. However, the controller design computations are identical to those of a standard LQG problem. The "time-domain method" emulates the same error signals by means of a multiplicative white noise model which reflects the time-domain behavior of those signals. The resulting robust controller is of the same order as the standard LQG controller, although the design involves a more complex computational algorithm. The application of multiplicative white noise to the system model requires the solution of a system of four coupled equations - two modified Riccati equations and two modified Lyapunov equations. In addition, the optimal projection equations are applied to both robustness methods to reduce the controller order with minimal loss in performance. Comparisons are drawn between these and related robust control methods, and it is shown that the relative effectiveness of such methods is problem dependent. Parameter sensitivity analysis is carried out on a simply supported plate model subject to external disturbances. The appropriate robust controller is selected, and it is found to stabilize the plate with little sacrifice in performance. / Ph. D.

Three models are proposed to evaluate and design distributed reconfigurable systems for fault tolerant, highly reliable applications. These models serve as valuable tools for developing fault tolerant systems. In each model, cells work together in parallel to change the global structure through a series of separate actions. In the Local Supervisor Model (LSM), selected cells guide the reconfiguration process. In the Tessellation Automata Model (TAM), each cell determines its next state based on its state and its neighbors' states, and communicates its state information to its neighbors. In the Interconnected Finite State Machine Model (IFS:MM:), each cell determines its next state and outputs based on its state and its inputs. The hierarchical nature of the TAM and IFSMM provides advantages in evaluating, comparing, and designing systems. The use of each of these models in describing systems is demonstrated. The IFSMM: is emphasized since it is the most versatile of the three models. The IFSMM: is used to identify algorithm weaknesses and improvements, compare existing algorithms, and develop a novel design for a reconfigurable hypercube. / Ph. D.

A new upwind scheme is developed for solving the three-dimensional Euler equations on unstructured tetrahedral meshes. The method yields solution accuracy and efficiency comparable to that currently available from similar structured-grid codes. The key to achieving this result is a novel cell reconstruction process which is based on an analytical formulation for computing solution gradients within tetrahedral cells. Prior methodology requires the application of cumbersome numerical procedures to evaluate surface integrals around the cell volume. The result is that higher-order differences can now be constructed more efficiently to attain computational times per cell comparable to those of structured codes. The underlying philosophy employed in constructing the basic flow solver is to draw on proven structured-grid technology whenever possible in order to reduce risk. Thus, spatial discretization is accomplished by a cell-centered finite-volume formulation using flux-difference splitting. Solutions are advanced in time by a 3- stage Runge-Kutta time-stepping scheme with convergence accelerated to steady state by local time stepping and implicit residual smoothing. The flow solver operates at a speed of 34 microseconds per cell per cycle on a CRAY-2S supercomputer and requires 64 words of memory per cell. Transonic solutions are presented for a broad class of configurations to demonstrate the accuracy, speed, and robustness of the new scheme. Solutions are shown for the ONERA M6 wing, the Boeing 747-200 configuration, a low-wing transport configuration, a high-speed civil transport configuration, and the space shuttle ascent configuration. Computed surface pressure-coefficient distributions on the ONERA M6 wing are compared with structured-grid results as well as experimental data to quantify the accuracy. A further assessment of grid sensitivity and the effect of convergence acceleration parameters is also included for this configuration. The more complex configurations serve to demonstrate the robustness and efficiency of the new method and its potential for performing routine aerodynamic analysis of full aircraft configurations. For example, the basic transonic flow features are well captured on the space shuttle ascent configuration with only 7 megawords of memory and 142 minutes of CRAY-YMP run time. / Ph. D.