Engineering Commons^™

A Thin-Film Micromanufactured Oxygen Microelectrode, James Clay Mcguyer Jr.

Doctoral Dissertations

The methods for production of recessed oxygen microelectrodes developed by Whalen, et al. (1967) and improved upon by Linsenmeier, et al. (1987) are dated production methods by the standards of sensor production of the current time. The production process for this type of polarographic oxygen sensing electrode has remained unchanged for over 10 years, and is a time consuming, extremely low-yield process. The goal of this project has been to use the techniques of micromanufacturing available at the Institute for Micromanufacturing at Louisiana Tech University to construct a recessed oxygen microelectrode with a batch process that has higher yield than …

The Microchannel Flow Of A Micropolar Fluid, Guohua Liu

Doctoral Dissertations

Micro-channel flows have been computed to investigate the influence of Navier-Stokes formulation for the slip-flow boundary condition, and a micro-polar fluid model, respectively.

The results of the slip boundary condition show that the current methodology is valid for slip-flow regime (i.e., for values of Knudsen number less than approximately 0.1). Drag reduction phenomena apparent in some micro-channels can be explained by slip-flow theory. These results are in agreement with some computations and experiments.

An ad hoc micro-polar fluid model is developed to investigate the influence of micro effects, such as micro-gyration, in micro-scale flows. The foundation of the ad hoc …

Finite Element Simulation Of Creep Buckling Of Cipp Liners Under External Pressure, Qiang Zhao

Doctoral Dissertations

The problem of long-term structural behavior of CIPP liners under external hydrostatic pressure has been characterized as a structural instability problem which is induced by time-dependent material deformation or creep. It is also a contact problem since the liner deflection is externally constrained by the host pipe. The intrinsically nonlinear problem is investigated by means of finite element simulation, with emphases on (a) the essential structural behaviors and mechanisms of buckling, and (b) the influences of inelastic material properties (i.e. yield strengths and creep rates) and geometrical parameters on liner's buckling resistance.

A liner first deforms as a free pipe …

An Empirical Investigation On The Impacts Of Ground-Level Ozone Concentrations On National Ambient Air Quality Standards: The Case Of Lake Charles, Louisiana, Benedict Nweke Nwokolo

Doctoral Dissertations

This study presents information upon which the state of Louisiana can base its ozone State Implementation Plans (SIPs) designed to achieve planned emissions reduction that are required by the Clean Air Act (CAAA) of 1990. The research investigation included an assessment survey on a number of Transportation Control Measures (TCMs) and their degree of acceptability by the residents of Lake Charles area of Louisiana, the research target area. The TCMS were first ranked on the basis of people's perception of each TCM and four TCMs were later analyzed for cost-effectiveness using computer mathematical models. The Traffic Flow Improvements TCM was …

Cracking In Cycloaliphatic Epoxy/Aluminum Composite Electrical Bushings, Keith Alan Parker

Doctoral Dissertations

The problem of cracking in electrical apparatus bushings as a result of thermal stresses was investigated. The bushings were composed of cycloaliphatic epoxy insulators with embedded aluminum conductors. The problem is due to the difference in coefficients of thermal expansion of the two materials. A solution to the problem had been to coat the conductors before they were formed together with the epoxy insulators. The coating was assumed to prevent cracking by allowing movement between the two materials as their dimensions changed during thermal expansion and contraction. The contribution of the coating was to be established.

The hypothesis was that …

Multifield Spectral Analysis Of Human Respiratory Sounds, John William Ray Jr.

Doctoral Dissertations

Computer analysis of human respiratory sounds (phonopneumography) has been attempted since the 1960s with poor results. Steady research efforts by numerous researchers have failed to yield a practical diagnostic tool to replace the physician and the stethoscope. This has been the result of the high degree of variability in proposed analysis parameters from subject to subject.

The purpose of this research is to examine a new approach to phonopneumography by comparing multiple lung fields of the same subject for the same breath in order to develop the diagnostic parameters. This approach has the advantage of allowing the subject to provide …

Graphical Display And Data Structure For Virtual Prototyping, David William Manry

Doctoral Dissertations

One of the goals of engineering firms is to bring better products to market faster. Although concurrent engineering can aid in this endeavor, it requires that all areas of an organization work simultaneously. Thus, current product data must be accessible to everyone.

Virtual prototyping allows this simultaneous exchange of information. Virtual prototyping not only replaces the physical model in product development with a virtual model, but also it goes further by allowing data associated with each part of the model to be accessed. This data is not limited to just geometric properties but could contain other quantifiable properties, such as …

Unbound Pavement Base Courses: Parallel Study Of Stiffness And Drainage Characteristics, Moussa Issa

Doctoral Dissertations

The purpose of this project was to study the effects of fines (minus #4 sieve) on permeability and stiffness characteristics of unbound base materials and to propose an optimumgradation that will satisfy these two parameters. One type of highway base material--crushed limestone--was used in the study. A total of 75 laboratory tests were conducted and distributed--25 respectively on permeability, resilient modulus and unconfined compression. The permeability test data were collected using a low-head permeameter. The resilient modulus and unconfined compression test data were collected by the mean of the MTS (Machine Testing System) with a load cell capacity of 22-kips. …

Sonar Three-Dimensional Image Formation For Underwater Vehicular Collision Avoidance, Gary Robert Boucher

Doctoral Dissertations

The last ten years have shown a marked increase in research into Autonomous Underwater Vehicles. A key component of this research is the ability to “look” ahead of the vehicle's projected path and translate active sonar returns into three-dimensional (3-D) computer data structures used to navigate and avoid obstacles. This need to avoid obstacles is also common to other underwater vehicles including submersibles.

Of special interest to this research is the “Occupancy Grid Framework.” This technique divides the forward looking sonar field into cells. These cells can be maintained either in spherical or cartesian coordinate systems.

This research demonstrates a …