Engineering Commons^™

An Investigation Of Multi-Dimensional Evolutionary Algorithms For Virtual Reality Scenario Development, Scott Papson

Theses and Dissertations

Virtual reality (VR) has emerged as a powerful visualization tool for design, simulation, and analysis in modem complex industrial systems. The primary motivation for this thesis is to develop a framework for the effective use of VR in design-simulation-analysis cycles, particularly in situations involving large, complex, multi-dimensional data-sets. This thesis develops a framework that is intended to support not only the integration of such data for visual, interactive, and immersive displays, but also provides a method for performing risk analysis. Previously "static" VR environments are enhanced with time-evolutionary capabilities. Four candidate algorithms are evaluated for this purpose – deterministic modeling, …

Three-Dimensional Shape Characterization For Particle Aggregates Using Multiple Projective Representations, Jonathan Paul Corriveau

Theses and Dissertations

Shape descriptors are used extensively in computer vision/automated recognition applications such as fingerprint matching, robotics, character recognition, etc. The conventional two-dimensional shape descriptors used in these applications do not readily lend themselves to compact representations in three dimensions. The situation is even more challenging when one attempts to numerically describe the three-dimensional shapes of a mixture of objects such as in an aggregate mix.

The goal of this study is the design, development and validation of automated image processing algorithms that can estimate three-dimensional shape-descriptors for particle aggregates. The thesis demonstrates that a single set of numbers representing a composite …

Heterogeneous Multi-Sensor Data Fusion Using Geometric Transformations And Parzen Windows For The Nondestructive Evaluation Of Gas Transmission Pipelines, Joseph Anthony Oagaro

Theses and Dissertations

The natural gas transmission pipeline network in the United States is a key component of the nation's energy supply infrastructure and extends for over 280,000 miles and has an average age of over 60 years. The integrity of the pipeline is maintained by periodic inline inspections using magnetic or ultrasonic pigs. Defect characterization algorithms developed using current pigging data are hampered by the fact that single inspection techniques (either magnetic or ultrasonic) do not yield sufficient information for accurately and repeatably characterizing defects. This thesis demonstrates that defect characterization algorithms using multiple inspection techniques can accomplish this task. In particular, …

Daubechies And Quadratic B-Spline Wavelets For Automated Early Diagnosis Of Alzheimer's Disease, Genevieve Jacques

Theses and Dissertations

Alzheimer's disease is a neurological disorder characterized by nerve degeneration and neuronal death. The diagnosis of Alzheimer's disease at an early stage is a major concern due to the lack of a standard and effective diagnosis procedure available to community healthcare providers, as well as the increasing numbers of the elderly population affected. Clinical evaluation, the standard AD diagnostic procedure conducted at major university hospitals and research clinics, achieves, on average, a positive predictive value of 93%, with a sensitivity of 83%, specificity of 55% and an overall accuracy of 75%. An effective and objective tool for early diagnosis of …

Vlsi Implementation Of An Efficient Method For The Computation Of Line Spectral Frequencies, David L. Reynolds

Theses and Dissertations

In speech coding applications using linear predictive techniques, the computation of line spectral frequencies (LSFs) from the predictor coefficients is an extremely computationally intensive task. The unique properties of the symmetric and antisymmetric polynomial roots limit the region which must be searched, however it is still necessary to perform a root-finding algorithm on a high-order polynomial.

Certain algorithms have been developed to reduce the complexity of the root finding exercise. One such algorithm, developed by Ramachandran and Kabal, takes advantage of certain properties of the symmetric and antisymmetric polynomials to map the upper portion of the unit circle onto the …

New Product Launch Decisions Under Competition And Uncertainty: A Real Options And Game-Theoretic Approach To New Product Development, James O. Ostler

Theses and Dissertations

New product development is central to many firms' future success. Not only as a means to continue to maintain their piece of the market, but product development can also be a strategic means for a company to diversify, and/or alter focus to adapt to changing market conditions.

Most of the research in new product development has been on how to do it cheaper and faster than the next guy. However, early commercialization does not guarantee a position of strength in the market. Failures of EMI in CT scanners and Xerox in personal computers illustrate that being first to market does …

Dynamic Stability And Handling Qualities Of Small Unmanned-Aerial-Vehicles Unmanned-Aerial-Vehicles, Tyler Michael Foster

Theses and Dissertations

General aircraft dynamic stability theory was used to predict the natural frequencies, damping ratios and time constants of the dynamic modes for three specific small UAVs with wingspans on the scale from 0.6 meters to 1.2 meters. Using USAF DatCom methods, a spreadsheet program for predicting the dynamic stability and handling qualities of small UAVs was created for use in the design stage of new small UAV concept development. This program was verified by inputting data for a Cessna-182, and by then comparing the program output with that of a similar program developed by DAR Corporation. Predictions with acceptable errors …

A Finite Element Simulation Of Temperature And Material Flow In Fricton Stir Welding, Mark J. Lasley

Theses and Dissertations

The purpose of this research was to use the Transvalor S.A. product, Forge3, to develop a finite element simulation of the friction stir welding process that improves the predictability of temperature evolution and material flow within the plunge portion of the process. Previous modeling created more heating within the billet than experimental results, probably due to the simplification of the simulation with adiabatic boundary conditions. More realistic tooling temperatures were included in this model as these affect heat evolution which is a determining factor in microcrystalline growth. These results were validated by experimental efforts using a billet and tooling instrumented …

A Method For Winding Advanced Composites Of Unconventional Shapes Using Continuous And Aligned Fibers, Abraham K. Allen

Theses and Dissertations

Advanced composites are extremely strong, rigid, and light, even when compared with advanced metals. Advanced composites are replacing high-tech metals as the material of choice for aerospace engineering. However, the processes used to manufacture advanced composites generally lose some of the properties of the materials by their process limitations.

One process that keeps the theoretically awesome qualities of the composite materials in tact is filament winding. Filament wound parts are used as rocket shells, bicycle frame tubes, drive shafts, pressure vessels, etc. Filament winding is an automated process and makes reliable parts to close tolerances. If a straight tube were …

Byu Micro-Sar: A Very Small, Low-Power Lfm-Cw Synthetic Aperture Radar, Michael Israel Duersch

Theses and Dissertations

Brigham Young University has developed a low-cost, light-weight, and low power consumption SAR for flight on a small unmanned aerial vehicle (UAV) at low altitudes. This micro-SAR, or uSAR, consumes only 18 watts of power, ideal for application on a small UAV. To meet these constraints, a linear frequency modulation-continuous wave (LFM-CW) transmit signal is utilized. Use of an LFM-CW signal introduces some differences from the typical strip map SAR processing model that must be addressed in signal processing algorithms. This thesis presents a derivation of the LFM-CW signal model and the associated image processing algorithms used for the uSAR …

Characterization Of Porous Media And Refractory Materials, Xin Chen

Doctoral Dissertations

Because of its unique advantages on energy savings and casting complex shaper, Lost Foam Casting (LFC) has been widely used as a replacement to the conventional techniques (sand and investment castings). In order to continuously improve the quality of the Lost Foam Casting process for reducing scrap rate and increasing energy savings, the US Department of Energy through its National Industrial Competitiveness through Energy, Environment, and Economics (NICEEE) program sponsored the present study to develop new characterization techniques for enhancing the understanding of the fundamental properties of the refractory materials used in The Lost Foam Casting process. In this study, …

An Adaptive Tool-Based Telerobot Control System, Ge Zhang

Doctoral Dissertations

Modern telerobotics concepts seek to improve the work efficiency and quality of remote operations. The unstructured nature of typical remote operational environments makes autonomous operation of telerobotic systems difficult to achieve. Thus, human operators must always remain in the control loop for safety reasons. Remote operations involve tooling interactions with task environment. These interactions can be strong enough to promote unstable operation sometimes leading to system failures. Interestingly, manipulator/tooling dynamic interactions have not been studied in detail. This dissertation introduces a human-machine cooperative telerobotic (HMCTR) system architecture that has the ability to incorporate tooling interaction control and other computer assistance …

Convergence And Robustness Issues In Computational Fluids, Xiaoqiang Zeng

Doctoral Dissertations

The present research develops two methods to improve the convergence and robustness of CFL algorithm, the triple time method and error- limited time step ramping method.

A general formulation of the triple time scheme is developed by introducing three pseudo time-marching steps to control three preconditionings for artificial dissipation, non-linear equation iteration convergence and linear equation iteration convergence separately. It is proven that the triple time method can be degenerated to the single time method and the multiple DDLGS iteration method at special cases.

Stability analysis is used to choose the optimum combination of three preconditionings from the steady preconditioning, …

High Accuracy Distributed Target Detection And Classification In Sensor Networks Based On Mobile Agent Framework, Xiaoling Wang

Doctoral Dissertations

High-accuracy distributed information exploitation plays an important role in sensor networks. This dissertation describes a mobile-agent-based framework for target detection and classification in sensor networks. Specifically, we tackle the challenging problems of multiple- target detection, high-fidelity target classification, and unknown-target identification.

In this dissertation, we present a progressive multiple-target detection approach to estimate the number of targets sequentially and implement it using a mobile-agent framework. To further improve the performance, we present a cluster-based distributed approach where the estimated results from different clusters are fused. Experimental results show that the distributed scheme with the Bayesian fusion method have better performance …

Synthesis And Ordering Of Nanostructures Using Laser Light, Yingfeng Guan

Doctoral Dissertations

This dissertation focuses on the formation of 1-D and 2-D nanoscale structures induced by the KrF excimer UV laser irradiation of silicon (λ=248 nm). Relatively low laser energy density (E_d<=1 J/cm²) is required to produce nanostructures. Alignment of 2-D nanoripple structures and nanoprotrusions has been realized by using Lloyd’s mirror configuration.

Laser-generated silicon microcone arrays were used as templates for the growth of nanocolumns. The formation mechanism of the microstructure is reviewed, and the origin and growth of nanocolumns are discussed. The formation mechanism of nanocolumns requires highly localized melting, which explains why they fail to form on …

A Study Of The Evolution Of Laser-Induced Periodic Surface Microstructures On Silicon And Electronic Transport In Composite Carbon Nanotube Networks, Stephen Jesse

Doctoral Dissertations

This dissertation addresses two main topics, the formation of micron-scale surface structures on single crystal silicon by irradiation with a KrF (248 nm) pulsed excimer laser source, and an investigation into electronic transport through composites of polymer (PMMA) and single-walled carbon nanotubes. It is shown that the spacing between laser-generated surface structures is determined primarily by the melt time and that the crystal orientation of the substrate can determine whether surface structures will form at all and also influence the shape of individual surface structures. During the melt/solidification cycle, the shape of liquid-vapor interface in modified by surface tension, and …

Fundamental Studies Of X-Ray And Secondary Electron Spectroscopy, Staya Prasad Mulapudi

Doctoral Dissertations

Microanalysis of submicron particles in the Scanning Electron Microscope (SEM) is only possible by using low incident electron beam energies due to smaller interaction volume and suppressed beam induced charging. Such low beam energies must use L- and M- lines rather than the familiar K-lines. The information about the fundamental parameters of X-ray emission and transport at low energies is limited, so the use of L- and M- lines is problematic. The rate of generation of X-rays from an element irradiated at some energy E depends on the product of the ionization cross-section (E) and the fluorescent yield . Unfortunately …

Modeling And Source Apportionment Of Primary And Secondary Pm2.5 In The Atmosphere, Prakash Doraiswamy

Doctoral Dissertations

Source apportionment of PM_2.5 is important to identify the source categories that are responsible for the concentrations observed at a particular receptor. Although receptor models have been used to do source apportionment, they do not fully take into account the chemical reactions (including photochemical reactions) involved in the formation of secondary fine particles. Secondary fine particles are formed from photochemical and other reactions involving precursor gases such as sulfur dioxide (SO₂), oxides of nitrogen (NO_x), ammonia (NH₃) and volatile organic compounds (VOC). The purpose of this research work was to model primary and …

Acoustic Wave Based Biosensor, Aditya A. Vijh

Masters Theses

Quartz Crystal Microbalances (QCMs) have been widely used for detection of various chemical and biological species in liquid media. In this work an improved binding of Protein A and IgG molecules on QCM biosensors by modifying the gold surface of the quartz crystal with an ultra thin polystyrene film followed by an acidic treatment has been reported. Protein A and IgG immobilizations on quartz crystals with the polystyrene film represented a 65% increase and a 40% increase respectively when compared to immobilization done directly onto the crystals. Atomic Force Microscopy (AFM) has been used to investigate and study the biomolecular …

Evaluation Of Seal Integrity Of Flexible Food Polytrays By Destructive And Non-Destructive Techniques, William James Barlow Jr.

Masters Theses

The military has recently suffered a reduction in production capacity due to the rejection of their flexible food packaging. The rejection of these polytrays was due to sealing defects and the high standards set forth for the sealing quality. These standards set by the military were likely too conservative and until a test could be developed and optimized to quantitatively measure seal integrity, the standards will remain very high. The optimized test, whether destructive or non-destructive, must show that a particular defect, which might currently cause rejection, will not affect the quality of the items contained if passed as a …

A Two-Phase Cooling Method Using R134a Refrigerant To Cool Power Electronics Devices, Jeremy Bryant Campbell

Masters Theses

Power electronics are vital to the operation and performance of hybrid-electric vehicles (HEVs) because they provide the interface between the energy sources and the traction drive motor. As with any “real” system, power electronic devices have losses in the form of heat energy during normal switching operation, which has the potential ability to damage or destroy the device. Thus, to maintain reliability of the PE system, the heat energy produced must be removed. Present HEV cooling methods provide adequate cooling effects, but lack sufficient junction temperature control to maintain long-term reliability. This thesis is based on using the automobile’s air …

Curvature Variation As Measure Of Shape Information, Sreenivas Rangan Sukumar

Masters Theses

In this thesis, we present the Curvature Variation Measure (CVM) as our informational approach to shape description. We base our algorithm on shape curvature, and extract shape information as the entropic measure of the curvature. We present definitions to estimate curvature for both discrete 2D curves and 3D surfaces and then formulate our theory of shape information from these definitions.

With focus on reverse engineering and under vehicle inspection, we document our research efforts in constructing a scanning mechanism to model real world objects. We use a laser-based range sensor for the data collection and discuss view-fusion and integration to …

Investigation Of Fiber Splitting In Side-By-Side Bicomponent Meltblown Nonwoven Webs By Additive Applications, Jihua Xiao

Masters Theses

Ever since the potential applications of superfine fibers were realized, bicomponent fibers have received considerable commercial interest. Webs containing microfine bicomponent fibers, such as bicomponent meltblown webs, have found great opportunities in production of finer fibers by subsequent fiber splitting, though technical problems still exist due to special features of the meltblown fibers, including low molecular orientation, low crystallinity and low strength.

In this research, the mechanics of polymeric interfacial adhesion in side-by-side bicomponent meltblown fibers was discussed and the method of enhancing the fiber splitting in bicomponent meltblown webs by additive application prior to the extrusion process was proposed …

Multiple View 3d Reconstruction Of Micro- To Nano-Scopic Specimens, Matthew Alan Schultz

Masters Theses

Range images and 3D modeling are often utilized on large scale specimens, but have been somewhat overlooked on the microscopic scale. This thesis concentrates on overcoming some of the difficulties of capturing images and creating both 3D models and 2D range images on this scale. During the scope of this thesis we take a deeper look into the optical mechanics of the laser scanning confocal microscope (LSCM) and scanning electron microscope (SEM) to understand the formation of the images and use that information to create our algorithms. With the use of the LSCM we can obtain a stack of 2D …

Combinatorial Design Of Nickel-Chromium Alloys By Physical Vapor Deposition And Electron Beam Welding, Jaret James Frafjord

Masters Theses

Combinatorial methods, which include high efficiency and high throughput methods to create a large compositional range of materials, have proven to be highly effective and efficient in research and development in the chemical and pharmaceutical industries. In this thesis, similar methods for the development and optimization of metals and alloy systems are explored. Combinatorial Ni-Cr alloy samples were developed by physical vapor deposition (PVD) of a wedged film on a bulk material, and then locally melting the two by electron beam welding (EBW). A combinatorial alloy gradient was thus created along the length of the weld. The samples were rapidly …

Lean Nox Trap Catalysis For Lean Burn Natural Gas Engines, Aaron Michael Williams

Masters Theses

As the nation’s demand for energy grows along with concern for the environment, there is a pressing need for cleaner, more efficient forms of energy. The internal combustion engine is well established as one of the most reliable forms of power production. They are commercially available in power ranges from 0.5 kW to 6.5 MW, which make them suitable for a wide range of distributed power applications from small scale residential to large scale industrial. In addition, alternative fuels with domestic abundance, such as natural gas, can play a key role in weaning our nations dependence on foreign oil. Lean …

Analysis Of Pilot Performance Using Precision Visual Flight Rules, Thomas Morrissey

Masters Theses

Precision Visual Flight Rules (PVFR) seeks to allow helicopter pilots to fly predetermined routes in high density traffic areas with greater precision by using a Global Positioning System (GPS). An analysis of the cross-track error during the PVFR developmental testing is presented. The primary objective is to determine the dominant factors which effect pilot performance using this higher standard of precision. Factors which are investigated include: total flight time, recent helicopter flight time, pilot ratings, and experience with the particular aircraft and GPS model. A conclusion is presented on which factors need to be addressed before opening up PVFR routes …

An Alternative Medium For The Measurement Of Soil Suction By The Filter Paper Method, Lori Ann Mcdowell

Masters Theses

Soil suction is the negative pressure within soil particles, which is a function of the moisture content. It plays an important role in agriculture, civil engineering, and geology. Suction is used in practice to identify expansive soils, to locate heave areas, to develop moisture requirements for arid land plants, to measure for collapse of soils around a footing, and to monitor flow movement of moisture. Soil suction varies with moisture content, and the relationship between suction and water content is known as the soil-moisture characteristic curve of a soil. There are several laboratory tests available to measure suction, but the …

3d Sound Synthesis Using The Head Related Transfer Function, Dayu Yang

Masters Theses

Three-dimensional (3D) sound is a significant component of virtual reality. 3D sound systems or directional sound systems are designed to animate the sound space produced by real sound sources. In this thesis, basic concepts of 3D sound are introduced. The Head Related Transfer Functions (HRTFs) are analyzed in both the time and frequency domain. A 3D sound system is implemented using practical, measured HRTF data.

A Computer Modeling Approach Using Critical Resource Diagramming Network Analysis In Project Scheduling, Vincent Gilles Delgado

Masters Theses

The problem of resource constrained project scheduling (RCPSP) continues to be an important topic in project management. Different scheduling processes have been introduced to solve cases of RCPSP. Most of the developed methods are based on a network analysis approach. The two main technique of project network analysis used for planning, scheduling, and control are PERT and CPM. These approaches assume unlimited resource availability in project network analysis. In realistic projects, both the time and resource requirements of activities should be considered in developing network schedules. Another particularity of the methods created, so far, is the focus on activities during …