We present an overview of mathematical models for electrons and holes in semiconductors. We use these to pose some inverse problems for determining the doping profile of a semiconductor. We establish the solvability of the equilibrium equation λ²∆u = e^u−e^(-u)–C in Ω. We also obtain information about the conductivity coefficient in the important case when it is piecewise constant and discontinuous. / Thesis (M.S.)--Wichita State University, Dept. of Mathematics and Statistics. / Includes bibliographic references (leaves 44-47). / "May 2006."

Pure oblique cutting experiments with conventional cutting tools as well as ultra-sharp tools have been carried out under a wide range of cutting conditions using a linear slide based cutting set-up. The chip flow direction was measured using the 3D Digital Image Correlation (DIC) technique of high-speed stereoscopic images and the frictional force direction was determined from forces. It is estimated that the error in chip flow angle measurements using DIC, was approximately ±1°, as was the error in friction force direction measurements from forces. An increasing trend of the angles with an increase in feed and a decreasing trend of the angles with an increase in speeds were observed. It was found that under many conditions, there is a significant difference between the chip flow direction and the friction force direction. This difference decreases with increase in friction co-efficient and with increasing sharpness of the cutting edge. However, with ultra-sharp microtome knives there is a small but finite difference between the chip flow direction and the friction force direction. By the use of DIC to measure the chip flow angle at different points along the back of the chip, it is found that there was no variation in chip-flow angle over the width of the chip. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering / Includes bibliographic references (leaves 65-67)

Seven boys who had received intervention for highly unintelligible speech were tested for metaphonological awareness skills and alphabetic knowledge at the beginning of the summer prior to their entering kindergarten. Five of these boys participated in 12 small-group [2-hour] sessions that incorporated lessons from a comprehensive multisensory early literacy program. Two of the seven boys were not able to participate in the sessions because of summer activity conflicts. Post-treatment scores were compared with pre-treatment scores for each of the boys and for the two groups. Results indicated that the children in the treatment group made substantially greater gains on tasks measuring metaphonological awareness skills and alphabetic principle knowledge during the 6-weeks period than the boys who did not receive services. / Thesis (M.A.)--Wichita State University, College of Health Professions, Dept. of Communication Disorders and Sciences. / "May 2006." / Includes bibliographic references (leaves 62-68)

Machines have become indispensable as part of our day today lives. They have made a stand in various fields like agriculture, construction, mining, materials handling, excavating and general use in industries. Skid Steer loader is one such machine which has the ability to fit into all of these categories. Skid steer loaders are known the world over for versatility and maneuverability. These are agile machines which have become a part of most industries. Their ability of having various attachments makes them proficient in handling tasks, which otherwise would be difficult for a human being. For these skid steer loaders to work to their full potential a skilled operator is required. Among other safety features, these skid steer loaders need to be accountable for the safety of the operator. So the cab mounted on these skid steer loaders need to conform to Roll Over Protective Structure also called as ROPS and Falling Object Protective Structure otherwise known as FOPS standards. There are various standards laid down by the International Organization for Standardization (ISO), Society of Automotive Engineers (SAE) and American National Standards Institute (ANSI) for these ROPS/FOPS cabs on skid steer loaders and other construction and mining equipments world over. This study deals with the composite modeling of ROPS/FOPS cab as per ISO 3471:1994 and ISO 3449:1992 Level I standards for skid steer loaders. In this research, a skid steer loader model with the operator cab is constructed and tested for the ISO standards. A section of the cab is then chosen and its properties are changed to composite properties. An attempt is made to use Glass fiber/epoxy composite materials for the section designed in this study. In addition, a parametric study is carried out on the section to satisfy the current standards in the industry. It is demonstrated that the section with the use Glass fiber/epoxy with a pertinent orientation and thickness may present more energy absorption than the present steel structure. It is demonstrated that the new designed composite section with Glass fiber/epoxy may be more effective than the present steel structure. With the advance in computer simulations, finite element (FE) model of the skid steer loader is used to predict the vehicle behavior in case of roll over. In addition, MSC Patran/Hypermesh has been used as the modeler and LS-Dyna as the solver to run the required simulations. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering / "May 2006." / Includes bibliographic references (leaves 53-54)

The aim of this study is to develop uniform pure bending as an objective test for determining the accuracy of springback prediction by employing different FEA techniques. A complete theoretical solution for the bending moment and change in sheet thickness is available only for uniform pure bending of perfectly plastic sheets. However, plastic hinging develops naturally in simulations of bending perfectly plastic sheets. We have developed a method to prevent plastic hinging and achieve uniform pure bending of sheets by applying constraint equations to nodes along the center fiber. The error in the bending moment for forming (E1), the error due to incomplete unloading during springback (E2), and error in the change of curvature corresponding to the change in bending moment during unloading (E3) are considered independently to get insights into the reasons for discrepancies between finite element analysis and theoretical results for springback. Uniform pure bending is also used to study the bending moment and springback experienced with work-hardening materials. Comparisons have been made with analytical solutions containing minor approximations in terms of the behavior of the material near the center fiber, which is subject to reverse loading. The fact that two different theoretical models for the material undergoing reverse deformation yield results that differ by less than 1% leads to a high degree of confidence in the theoretical models. We have used uniform pure bending to study the inherent springback prediction capability of different types of element analysis, convergence parameters, and discretization level in two different finite element analysis packages, namely MARC and ABAQUS. For simulations in ABAQUS using two dimensional elements and a perfectly plastic material model, the bending moment given by FEA is less than that predicted by the theoretical model by about -3%, indicating lesser springback than that predicted by theory. However for three dimensional elements, the bending moment is higher by about 10% for a relative curvature (%) of 0.2. For a coarse discretization (about 4 elements around a 90° bend), this error increases to about 37%. For a work-hardening material model, two dimensional elements predict 12% less bending moment than the theory, indicating an under-prediction in springback. Shell elements with reduced integration give an under-prediction of springback and show a negative error value between 2% and 10% for the simulations with different integration points, while shell with full integration show a positive total error of abut 3%, indicating a higher springback than predicted by theory. Changing the convergence tolerance value by 100 from the default value shows a 2% change in calculated results. For MARC, the two dimensional elements under-predicts springback by 10%, while the three dimensional elements have shown over-prediction up to 30% in moment calculations. Based on the findings, uniform pure bending is recommended as a benchmark test for identifying the intrinsic accuracy with which springback can be predicted by FEA simulations using different simulation parameters. Uniform pure bending can be used to develop effective guidelines for reliable finite element simulations of springback. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering / "May 2006." / Includes bibliographic references (leaves 52-54)

Today occupant safety is of a prime concern to every car manufacturer. New standards are being set for the safety of the occupant in different crash scenarios like frontal head on collision, angle impacts, side impacts, rear impacts and rollover. Among these standards, frontal impact is one of the fatal crash scenarios that lead to death of scores of people in the United States and across the globe. The automotive mid-rail is the main load carrying/energy-absorbing component in a event of frontal vehicle crash. In the contemporary world, fuel consumption also poses a serious issue that has to be considered. With these constraints in consideration, a lighter and stronger composite material is used in car front rail than steel. Using this material would help in reducing the fuel efficiency without sacrificing the safety of the vehicle. In this research, section modeling of rails is designed to replace the present rail model and the injury sustained by the occupant is recorded. An attempt is made to use Carbon fiber/Epoxy and Glass fiber/epoxy composite materials for the rails. In addition, parametric study is carried out on the rail to find out the maximum possible energy absorbing parameters. It was found that carbon/epoxy rail with a pertinent orientation and thickness was absorbing more energy than the present steel rail. Energy absorption, displacement and the acceleration of the original and section model is compared and discussed in detail. The Ford Taurus model is first validated using the LS-DYNA finite element software package and then dynamic analysis is performed on the original model and the section model according to the Federal Motor Vehicle Safety Standard (FMVSS) 208, the New Car Assessment Program (NCAP) and the Insurance Institute for Highway Safety (IIHS) regulations. The vehicle displacements, Energy absorption and deceleration levels are compared for the steel, carbon-fiber epoxy and glass-fiber epoxy model. The occupant injuries are then evaluated for the full width rigid barrier test at 30 mph and 35 mph using the MADYMO, occupant modeling software package. With the new composite model and the section model the injury levels including, the head, neck and chest injuries are evaluated and compared. It is demonstrated that the new composite rail with carbon/epoxy is more effective than the present steel rail. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering / "May 2006." / Includes bibliographic references (leaves 108-110)

Archaeologists have long recognized the fact that long distance relationships existed in prehistoric societies. There have been many efforts to develop models for a satisfactory explanation for interactions and social change among groups. World Systems Theory, developed by Immanuel Wallerstein, is one such effort to examine mechanisms of inter-societal relationships and a determination of units of analysis for Pre-Columbian societies. To utilize this theory, archaeologists have made modifications and expansions to the theory, determining the advantage of using a world systems perspective, rather than all aspects of the model. An examination of Wallerstein’s theory, as well as assessments and concerns regarding modifications, is examined. The premise that societies do not exist in isolation is one that should concern all archaeologists. / Thesis (M.S.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Anthropology. / Includes bibliographic references (leaves 48-57). / "May 2006." / Includes bibliographic references (leaves 48-57)

Atherosclerosis is a leading cause of heart diseases and mortality around the world. Recently cryoplasty has emerged as a potentially effective method to treat atherosclerosis. Finite element heat transfer and mass transfer models are developed in ANSYS in this study. The heat transfer model analyzes the heat transfer within the atherosclerotic plaque and arterial wall during the cryopalsty procedure. The model is useful in predicting the transient temperature through diseased wall tissues. The measurements can be used to decide the required treatment procedure effectively for freezing the plaque with minimal damage to the healthy arterial tissues. The model investigates the parameters that may effect temperature distribution within the tissue during the ablative procedure. A mass transfer model is developed using ANSYS to study the pressure effects on molecular diffusion across the arterial wall and the permeability effects of endothelial membrane during the molecular diffusion process. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering / "May 2006." / Includes bibliographic references (leaves 89-95)

Many studies of hyper saline environments have been performed, mainly on aquatic systems. However, the microbial community in terrestrial thallasohaline environments has not been studied extensively. To our knowledge, this is the first study of a natural terrestrial thallasohaline environment using polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE). We studied the great salt plains (GSP) for this purpose. The GSP is a perfect example of an extreme environment. The environment of the GSP changes frequently due to rain events that can change the salinity of the soil. Salt gradient samples and core samples were collected from the GSP in different years and DNA extractions were performed. 16S rRNA genes were amplified using PCR and examined on DGGE gels. Banding patterns of the DGGE gels were analyzed using Quantity One-Versa Doc software. Based on the banding patterns after DGGE, it was shown that the low- and high-salt soil samples had greater band richness than medium-salt soil samples. A dendrogram of relatedness was made and the samples were placed in different phenons using NTSYS. Core samples collected from the same locations exhibited similar microbial communities, and samples collected in different years from same location exhibited different microbial communities. Environmental factors such as soil salinity, water flow, and temperature, vary from year to year and from place to place on the GSP, which can select for different microbial communities in soil samples collected from the same place in different years and soil samples collected from different places on the GSP. / Thesis (M.S.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Biological Sciences. / "May 2006."

This thesis presents a cost analysis of grid-connected electric energy storage. Various battery energy storage technologies are considered in the analysis. Life-cycle cost analysis is used. The results are presented in term of incremental cost of electricity stored and discharged, in US$/kWh / Thesis (M.S.)--Wichita State University, Dept. of Electrical and Computer Engineering. / "May 2006." / Includes bibliographic references (leaves 47-49)