Thesis (Ph. D.)--University of Wisconsin, 1964. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 85-86.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1960. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 67-68).

Thesis (doctoral)--Rheinische-Westfälische Technische Hochschule, Aachen, 1981. / Includes bibliographical references (p. 83-88).

Thesis (Ph. D.)--University of Michigan, 1936. / Reprinted from two articles, by F.E. Bartell and Mike A. Miller, published in the Journal of physical chemistry, v.40, no. 7, October, 1936. Bibliography: p. 12, 21-22.

Thesis (MSc)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.

Humic substances are ubiquitous in nature, constituting the major fraction of organic materials present in soils. They are polymeric, polyelectrolytes and are known to form water soluble complexes with metals. Whilst their metal complexing ability has been widely studied, few studies have been conducted on their ability to transport metals through the terrestrial environment. Laboratory studies were undertaken to investigate those factors which may affect the transport of metal-humic complexes through columns of porous geological media. In the main, intact Clashach sandstone columns were used. The transport studies concentrated on europium (¹⁵²Eu) complexed to humic material radiolabelled with ¹²⁵I, so that the measurement of both species was facilitated at low concentrations. In order to measure the sorption of both the metal and humic species along the column and in the effluent, a computer operated dual detector instrument was designed and built. Initial studies comparing two methods of introducing the complexes onto packed sand columns viz. injection and flooding suggested that for tracer studies both methods were acceptable. However for metal complex migration studies insufficient activity was recovered from the injection technique to produce meaningful results. The effect of humic coating, and the presence of iron within the column, on the recovery of various metal humate complexes from both packed and intact columns were investigated. The presence of humic materials greatly increased the recovery and mobility of the europium, but was found to retard the mobility of cadmium and zinc. The presence of iron both naturally occurring in the column materials and added to the packed columns as goethite was shown to greatly retard the mobility of europium, cadmium and zinc. The effect of flow rate and column length on the recovery of europium humate from Clashach sandstone cores was also studied. Europium recovery was found to be related to the flow rate through the column, suggesting a kinetically controlled sorption step. Europium recovery was not found to be directly related to the column length as a high proportion of the metal is sorbed within the first few centimetres. The recoveries and mobilities of europium humate complexes were then modelled using a simple model. Batch equilibrium experiments were conducted to determine the extent of sorption of metal humate complexes on both natural sands and on crushed Clashach sandstone of differing surface areas.

The reliability of systems relies heavily on accurate fatigue life prediction of related components. Fatigue life prediction is a complicated process requiring the correct methodology to determine accurate and reliable predictions. The Palmgren – Miner damage accumulation hypothesis is widely used in determining the fatigue life of components exposed to variable loading conditions. Modifications have been made to this hypothesis trying to achieve a greater degree of accuracy, of these the Liu – Zenner modification has been the most successful. In this report the systematic process of fatigue life prediction using the Liu – Zenner modification to achieve reliable results is calculated. A representative stress time history measured in service on the component forms the basis for defining a flight cycle which is the chosen unit in which to express the fatigue life. Rainflow cycle counting performed on the stress time history allowed the formulation of a load spectrum to which the component is exposed in one cycle. Combining the load spectrum with the developed SN curve of the component and using the Liu – Zenner modification to the Palmgren – Miner rule a reliable fatigue life in cycles is predicted.

Uni-directional stresses have been applied, to copper wires, and the potential difference between such wires and unstressed wires determined in various electrolytes. The potential differences have been determined both by a galvanometer method and potentiometrically. The latter method gave more consistent results and is thought to eliminate some of the possibilities of polarization. Some correlation has been found between the amount of applied stress and the potential difference observed, and thermodynamic arguments have been advanced to explain such results, at least qualitatively. A correlation of these same results with time has led to the conclusion that the potential difference is essentially due to a surface effect. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

An extensive creep study of a superplastic material has not previously been made. The present study was carried out to determine if there are any basic differences between the creep of coarse grained materials and fine grained super-plastic materials. The results give information about the mechanical properties of superplastic alloys and are relevent to an understanding of the mechanics of superplasticiy. At high strain rates the superplastic lead-tin eutectic deforms by recovery creep and a 3-stage creep curve is observed, similar to that found for coarse grained materials. As the strain rate is decreased, the initial transient (primary creep) disappears and the creep curve is linear until necking occurs and tertiary creep ends in failure. In the principal superplastic range, at medium strain rates, creep curves are linear to at least 50 % strain. The recovery rate is immediately equal to the strain hardening rate and there is no primary creep. At low strain rates the creep curve is slightly convex as the creep rate decreases with time. This may be due to the self extinguishing nature of diffusional creep or possibly strain induced grain growth. These results are consistent with the grain boundary sliding theories of superplasticity although details of the accommodation processes are not known. At the lowest strain rates, diffusional creep may operate. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate