The stress-strain and volume (or pore pressure) change characteristics of a Southern Arizona copper mine tailings material were investigated in the laboratory by conducting static loading triaxial compression tests. The tailings material is silty sand with highly angular grain shapes, rough grain surface texture and approximately 37% by weight passing No. 200 sieve. Isotropically consolidated drained (CID) and isotropically consolidated undrained (CIU) tests were performed on laboratory compacted samples. The test samples were loaded to relatively large axial strains (20-35%) to study the residual shear strength and the shear stress induced pore pressure change or volume change at steady state. Test sample densities and effective confining stresses were systematically varied in these tests. The definition of critical void ratio and "lower" critical void ratio were reviewed and their values for different effective confining stresses were obtained from the CID tests. Stress-strain and volume (or pore pressure) change curves and strength parameters obtained by using conventional and lubricated loading end platens were compared and discussed. Steady state lines and undrained brittleness indices were obtained from the CIU tests with strain-controlled and load-controlled loading methods. The liquefaction potential of the tailings material was then evaluated. These results were compared with others reported in the literature. The significance of the results was discussed with respect to tailings material behavior.

The evolution of the large scale structures and the mean field were investigated in axisymmetric and plane mixing layers. Some aspects of the linear instability of an axisymmetric jet have been demonstrated. The axisymmetric geometry admits two additional length scales with relation to the two-dimensional shear layer: the radius of the jet column and the azimuthal wavelength. The importance of these two length scales in governing the instability of an axisymmetric jet was explored. The special case of a thin axisymmetric shear layer was analyzed and the results stressing the evolution of different azimuthal modes were compared with some phase-locked data which was produced by subjecting the jet to axisymmetric and helical excitation. The importance of the initial spectral distribution in a natural jet was demonstrated when it is used as an input to the amplification curve obtained from linear stability theory to predict a measured spectral distribution at a further downstream location. The inclusion of the nonlinear terms in the stability analysis reveals two main interactions: mean flow-wave interaction and wave-wave interaction. The modification of the mean flow of an axisymmetric jet was examined by exciting two azimuthal modes simultaneously. The interaction resulted in an azimuthal modulation of the mean velocity profile having a cosine shape. Effectively, the geometry of the jet was modified without changing the geometry of the nozzle. The coupling between an excited periodic disturbance and the mean flow was analyzed and the spatial evolution of both were compared with experimental results obtained in a plane mixing layer. The behavior of the concommittant Reynolds stresses is discussed in detail. The conditions under which one disturbance will transfer energy to another were derived and demonstrated in an axisymmetric jet. The interaction between a large amplitude plane wave with a weak subharmonic component was shown to enhance the amplification rate of the subharmonic. It was further shown that the nonlinear interaction between two azimuthal modes can produce a third azimuthal mode which was not initially present in the flow. The coupling between a fundamental wave and its subharmonic in a parallel plane mixing layer was demonstrated numerically.

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Tension and Compression force deformation data from laboratory tests of angle segments are used to generate moment rotation curves for the following bolted partially restrained connections: (1) top and seat angle, (2) double web angle, and (3) top and seat angle with double web angles. The force deformation and moment rotation curves are analytically described by a four parameter formula which provides the basis for the analytical connection model. These connection models consist of rigid bars and nonlinear springs representing the angle segments in either tension or compression. Design curves giving the four parameters of the moment rotation curves are generated for the double web angle connection. These parameters are primarily a function of the angle thickness, gage length of the angle legs in flexture, and the number of bolts in the connection. Comparisons of derived moment rotation curves are made with published results of full scale tests.

In the hierarchical approach of constitutive modelling, the damage accumulation and resulting strain-softening behavior of geologic materials can be modelled by introducing a concept of damage evaluation. The damage accumulation and softening behavior are affected by the size of specimens. A series of uniaxial tests on cylindrical specimens of a simulated rock were performed. The effect of specimen size on the parameters of the damage model were investigated by using the test results. The empirical results show that the damage parameters can be related to a characteristic dimension, which was expressed in terms of length and diameter of the specimen.

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A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in the fulfilment of the requirements for the Degree of Master of Science in Engineering. 1992 / The absence of reliable design data for Glass Reinforced Plastic (GRP) road tankers has been considered an obstacle for the local design and manufacture of such vehicles. This has prompted the analysis, using Finite Element Methods (FEM) of a filament wound cylindrical shell for a monocoque road tanker. [Abbreviated Abstract. Open document to view full version] / GR 2016

A Dissertation submitted to the Department of Physiology, University of Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Master of science in Medicine. / The management and prevention of ankle sprains had been a topic of controversy in the sport medical literature to date, with various rehabilitative and preventative protocols having been suggested. In part one of this study, a relatively new rehabilitative device, the Cybex II Dynamometer,was used to determine whether the rehabilitation period of ankle sprain injuries could be reduced in recently injured patients. In part two, the Cybex II Dynamometer was used in conjunction with other training techniques in a preventative trial of first league volleyball players, to see whether the incidence of ankle sprains (which is particularly high in this population group) could be reduced. Although the experimental group was discharged almost 35 percent sooner than the control group in part one, the difference was not found to be statistically significant. In part two the preventative measures resulted in a notable difference in the incidence of injuries (32 percent in the control group compared to 11 percent in the experimental, group). Differences were just not statistically significant (p=O.059). / Andrew Chakane 2018