Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 7 of 7

Full-Text Articles in Engineering

Mathematical Modeling Studies Of Electrochemical Growth Of Oxide Films On Metals , Mei-Hui Wang Jan 1998

Mathematical Modeling Studies Of Electrochemical Growth Of Oxide Films On Metals , Mei-Hui Wang

Retrospective Theses and Dissertations

This dissertation consists of two parts. First, a mathematical model was formulated to investigate the structural change of the oxide film on aluminum due to cathodic charging. The model assumed a duplex film structure composed of a barrier layer on the metal side and a porous layer on the solution side. The processes formulated in the model include all relevant capacitive processes, conduction in both layers of the oxide film, and interfacial reactions, such as pore filling by oxide growth at potentials higher than the open circuit potential. The model was fit with the anodic current transients during subsequent anodic ...


The Effects Of Physiological Levels Of Intermittent Pressure On The Development Of Articular Cartilage In Vitro , Scott Edward Carver Jan 1998

The Effects Of Physiological Levels Of Intermittent Pressure On The Development Of Articular Cartilage In Vitro , Scott Edward Carver

Retrospective Theses and Dissertations

A semi-continuous perfusion system has been designed and constructed to deliver physiological levels of hydrostatic pressure to regenerating cell/polymer constructs of articular cartilage over the long term (weeks to months). Prior to being transferred to the pressurized system, equine articular chondrocytes were dynamically seeded onto nonwoven meshes of polyglycolic acid which provide the cells with a three-dimensional growth environment similar to that found in vivo. When applied in an intermittent manner, physiological pressurization at 500 psi was found to stimulate articular chondrocytes to produce regenerated constructs with greater concentrations of sulfated glycosaminoglycan compared to control (unpressurized) constructs, while the ...


Process Analysis And Yield Enhancement For The Production Of Beta-Hydroxy-Beta-Methyl-Butyrate (Hmb) , George Barac Jan 1998

Process Analysis And Yield Enhancement For The Production Of Beta-Hydroxy-Beta-Methyl-Butyrate (Hmb) , George Barac

Retrospective Theses and Dissertations

The purpose of this work was to develop an optimum chemical process philosophy for the manufacture of [beta]-hydroxy-[beta]-methyl-butyrate (HMB), using existing synthesis and purification schemes as a starting point. Process analysis and improvement were performed as a means to increase overall efficiency and to address environmental concerns;A protein breakdown suppresser, HMB is used as a nutritional supplement or as a feed additive. The current process which employs reaction of diacetone alcohol and sodium hypochlorite, separation of the product by batch extraction, and crystallization, displays very low efficiency and has to deal with waste disposal issues. Currently ...


A Kinetic Study On The Adsorption And Reaction Of Hydrogen Over Silica-Supported Ruthenium And Silver-Ruthenium Catalysts During The Hydrogenation Of Carbon Monoxide , David Paul Vanderwiel Jan 1998

A Kinetic Study On The Adsorption And Reaction Of Hydrogen Over Silica-Supported Ruthenium And Silver-Ruthenium Catalysts During The Hydrogenation Of Carbon Monoxide , David Paul Vanderwiel

Retrospective Theses and Dissertations

An interesting phenomenon in bimetallic catalysis is the synergistic effect between two metals during CO hydrogenation. For example, addition of Ag to Ru catalysts results in a dramatic decrease in the specific activity of the catalyst, even though Ag alone does not appreciably adsorb H2 or CO. A series of Ag-Ru/SiO2 catalysts containing 0, 3, 10, 20 and 30 atomic percent silver was used to examine the kinetics of the adsorption and reaction of H2 on Ru during CO hydrogenation. CO was saturatively adsorbed at room temperature on each catalyst, followed by subsequent reaction with ambient H2 at 460 ...


Development Of A Coupled Model Of The Cardiorespiratory And Thermoregulatory Systems , Dawn Denise Downey Jan 1998

Development Of A Coupled Model Of The Cardiorespiratory And Thermoregulatory Systems , Dawn Denise Downey

Retrospective Theses and Dissertations

A model of the human body which integrates the variables involved in temperature regulation and blood gas transport within the cardiovascular and respiratory systems is presented in this dissertation. It expands upon previous work developed by the author to model the competition between skin and muscles when both require increased blood flows during exercise and/or heat stress. First, a detailed study of the control relations used to predict skin blood flow was undertaken. Four other control relations employed in the model were also examined and modified as indicated by empirical results found in literature;Several important cases were then ...


Thermodynamic Availability Analysis Of Controlled Air Revitalization Systems , Caroline Kirsten Wilharm Jan 1998

Thermodynamic Availability Analysis Of Controlled Air Revitalization Systems , Caroline Kirsten Wilharm

Retrospective Theses and Dissertations

This work investigates thermodynamic lost work and several of the factors influencing its production. Lost work is a measure of irreversibilities within a process, and its characterization can aid in improving the design of a system. Lost work is equivalent to consumed availability, where availability is a measure of the capacity of a system to perform useful work;Lost work is a function of mass flows, chemical species and their relative concentrations, temperature, and pressure. To examine how these variables influence lost work production, systems of different levels of complexity were studied. The simplest system was comprised of three isothermal ...


Structure Sensitive Adsorption Of Hydrogen On Ruthenium And Ruthenium-Silver Catalysts Supported On Silica , Naresh Kumar Jan 1998

Structure Sensitive Adsorption Of Hydrogen On Ruthenium And Ruthenium-Silver Catalysts Supported On Silica , Naresh Kumar

Retrospective Theses and Dissertations

Supported metal catalysts typically consist of particles with sizes less than 10 nm, and because of the small crystallite size, low coordination number sites (edges and corners) represent a significant fraction of all surface sites. Furthermore, it has been demonstrated that adsorption rates can be much greater at these low coordination sites than on basal plane sites. What has not been generally appreciated, however, is that preferential adsorption at edge and corner sites may explain the mechanism by which a promoter, or the addition of a second metal to form a bimetallic, can alter the selectivity and rate of reaction ...