Engineering Commons^™

Automated Fault Detection In An Upflow Anaerobic Sludge Blanket Reactor: Comparisons Of Biogas Production And Physicochemical Quantities, Alexandra Maria Almeida Carvalho Pinto

Doctoral Dissertations

A system capable of rapidly detecting toxic loads entering high-rate anaerobic reactors would greatly enhance their reliability, and could thereby increase their commercial acceptance. A high-rate anaerobic wastewater treatment process, called the failure-causing load detector (FCLD), consisting of a small (4-liter) upflow anaerobic sludge blanket (UASB) reactor having a short (10-min) hydraulic retention time (HRT), was used as a biosensor to rapidly detect potential problems with the influent wastewater. Sensors were used to monitor biogas production in the reactor, as well as pH, conductivity, and turbidity in the effluent from the reactor. The FCLD system was tested using the following …

Development Of A Model For Predicting The Vertical Profile Of Ozone Based On Ground-Level Ozone Observations And Cloud Cover, Gi-Dong Kim

Doctoral Dissertations

Ozone formed in a chemical reaction is vertically dispersed and mixed with the ozone mass aloft by turbulent convection due to solar radiation. The mixing height, which depends on the stability of the atmosphere, varies by day/night time and by season of year and is characteristic of season and day and night time from year to year. Ground level ozone is generally the combined result of dynamics of the atmosphere resulted from the turbulent convection in the atmospheric boundary layer (ABL), production and destruction processes such as transport from upper air mass, subsequent transport to the ground, photochemical production and …

Effect Of Bonding Variables In Thermal Bonding Of Polypropylene Nonwovens, Praveen Kumar Jangala

Doctoral Dissertations

The aim of this research was to investigate the effect of some of the process variables on the structure and properties of the webs in a thermal point bonding process. The main objectives were to understand the changes taking place in the fiber structure due to applied heat and pressure, the effect of bond area and bond size on fiber morphology, and the physical properties of the web. Thermally bonded carded webs were produced and characterized in order to determine the role of bond area and bond size on strength and stiffness of the point bonded fabrics and fiber morphology. …

Surface Texture And Micromechanics Of Ultra High Molecular Weight Polyethylene (Uhmwpe) Orthopaedic Implant Bearings, Monica A. Schmidt

Doctoral Dissertations

Tibial bearings of ultra-high molecular weight polyethylene (UHMWPE) were characterized to identify differences in morphology, surface texture (roughness and skewness), and micro-scale mechanical behavior. These orthopaedic implant components were fabricated by direct molding or by machining after isostatic compression molding. Sterilization was by gamma irradiation (3.3 Mrad) in air, followed by shelf aging for 2 years. Comparisons were made between unsterile and sterile bearings to identify differences in structure and properties related to wear debris.

Characterization methods included confocal optical microscopy, nanoindentation , small angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry …

An Externally-Synchronized Coherent Communication System Design, Gary R. Ragsdale

Doctoral Dissertations

The research described within this dissertation was initiated on October 1, 1997 to investigate communication link performance improvements made possible by using a frequency reference supplied by a residual carrier broadcast. The primary link types considered were radio frequency links, although prior research in externally-synchronized bistatic radar was also considered.

Conventional radio frequency communications links transfer information from transmitter to receiver by modulating a carrier signal at the transmitter and demodulating the received signal at the receiver. Demodulation can be done coherently or noncoherently. That is, the information on the received signal can be recovered by comparison of the received …