In South Africa mineral processing is a very important activity and ""lith declining om grades and increased need for foreign' revenue it is necessarv to develop methods which wUl keep are processing'~osts as low as possible. (( Milling is an example of a capital intensive unit operation 'which has much scope for more efficient Operation. Better control of the viscosity of the slurry discharged from a rotary 9rir~ding mill will result in improved milling efficiency and hence a saving 1'1electricity ~nd steel costs will be experienced. More effective and conslstent grinding in the mil! will also result in em lmproved mineral recovery. Slurry rheology is the variable of interest in monitoring and controlling a wet grinding mill rather than other rneascres of slurry composition presently used (eg percent solids). Up to this point in time however this variable has not been successfully used due to the fact that a sufficiently reliable and robust device for measuring the viscosities of slurries on an on-line basis has riot been available, This project was undertaken to develop just such a device (which is in the process of being patented bV Professor M H Mays). The flow rate of a fluid down a vertical tube is a function if its viscosity as well as ether quantifiable variables. This is the basis of the operation of the measurement device. Useful features of this device Include the fact tl'tat it has no movin~ paris, is inexpensive and robust and is subject tli) little wear. ''rha measurement can b --------------------------------------.--~~-----~------ performed directly on the stream in question and it is unlikely to be blocked up by fibres/particles. A self cleaning facility may also be Included. Ba$ed On the experimental results the technique shows much promise and it is anticipate:ted that the basic design could easily evolve into a useful, practical devi~e for th~ measurement of the apparent viscosity of settling slurries as well as other fluids. If a differential pressure tell" Is also connected to the device it may be used to obtain the density of the fluid being sampled. A model based on the. principles of conservation of momentum was developed and solved numerically using MATLAB {which uses 5th order Runge Kuttal as well as a Turbo pascal program using 4th order Runge i<utta. The model was also' simp.lified slightly by neglecting acceleration of th~ flui¢ (a simplificatlcbn which was shown ~xperimentally to hold) and solved analytically. The results predict~d by the model ~3~ffar only slightly from the experimentally determined i' results. The devil~e has been tested on pilot mills at MINTEK's research facility as wall as the Anglo American Research labs, with varying degrees of success.

by Xin-liang Qiu. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (p. 98-103). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese. / by Xin-liang Qiu.

Yu, Rongfeng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (p. 57-63). / Abstracts in English and Chinese. / Introduction --- p.3 / Chapter 1 --- Preliminaries --- p.11 / Chapter 1.1 --- Notations and function spaces --- p.11 / Chapter 1.2 --- Some useful inequalities --- p.12 / Chapter 1.3 --- Fundamental lemmas --- p.15 / Chapter 2 --- Compressible Navier-Stokes Equations for Quantum Fluids --- p.16 / Chapter 2.1 --- Background --- p.17 / Chapter 2.2 --- Derivation of model --- p.17 / Chapter 3 --- Global Weak Solutions to Barotropic Navier-Stokes Equations for Quantum Fluids --- p.22 / Chapter 3.1 --- Reformulation and main results --- p.23 / Chapter 3.2 --- Construction of approximate solutions --- p.27 / Chapter 3.3 --- A priori estimates --- p.39 / Chapter 3.4 --- Proof of Theorem 3.1.6 --- p.40 / Chapter 4 --- Global Existence and Large Time Behavior of Weak Solutions to Quantum Navier-Stokes-Poisson Equa-tions --- p.46 / Chapter 4.1 --- Global existence of weak solutions --- p.47 / Chapter 4.2 --- Large time behavior --- p.50 / Chapter 5 --- Discussions and Future Work --- p.55 / Bibliography --- p.56

This thesis examines the flow of very viscous Newtonian fluids driven by gravity. It is written with concern for specific applications in the optics industry, with emphasis on the slumping of molten glass into a mould, as in the manufacture of optical components, which are in turn used to manufacture ophthalmic lenses. This process is known as thermal replication. However, the work has more general applicability, and disc viscometry, used to determine the viscosity of very viscous fluids, is also considered. In addition, one chapter of the thesis is devoted to the flow of dripping honey, as another example of a very viscous flow to which the model can be applied. The Stokes creeping-flow equations are used to model the very viscous flows of interest. The main solution method is finite elements, and a purpose-written computer program has been developed to solve the creeping-flow equations by this method. The present program is restricted to solving for either two-dimensional or axisymmetric flows but is extendible to three dimensions. In addition, semi-analytic series and asymptotic methods are used for some small portions of the work. The optical applications of this work demand consideration of the topic of computing surface curvature, and therefore second derivatives, from inexact and discrete numerical and experimental data. For this purpose, fitting of B-splines by a least-squares method to coordinate data defining the surface has been used. Much of the work assumes isothermal conditions, but in the context of the accuracy required in optical component manufacture it is also possible that non-isothermal effects will be important. Consequently, this restriction is eventually relaxed and some consideration given to non-isothermal conditions. In order to validate the creeping-flow model and finite-element program, comparisons of numerical simulations with experimental results are performed. A preliminary assessment of the importance of non-isothermal conditions to the thermal-replication process is also made by comparing isothermal and non-isothermal simulations with experimental results. The isothermal model is found to best match the experimental data. / Thesis (Ph.D.)--School of Applied Mathematics, 1998.

Highway bridges function as the arteries of our society. Hence, it is essential that they remain operational following an earthquake. Unfortunately, a significant number of bridges worldwide, including in Canada, were constructed prior to the development of modern seismic design provisions. In many cases, such bridges are expected to perform poorly during earthquakes. According to a report published in 2000 by Ministry of Transportation of Ontario (MTO), in eastern Ontario alone, there are over 70 bridges that are structurally deficient. Current methods to retrofit these bridges to bring them into compliance with the existing codes would entail substantial structural modifications. Examples of such modifications include the replacement of existing rocker bearings with elastomeric bearings, structural strengthening of piers, and enlarging the bearing surfaces. These methods involve substantial cost, effort, and materials. An alternative means to retrofit structurally deficient bridges is investigated in this thesis. This method involves using a combination of elastomeric bearings and fluid dampers to retrofit highway bridges. In principle, these devices work in the same way as shock absorbers in automobiles. They absorb shock and dissipate the vibration energy to the environment as heat. In the case of bridges, earthquakes impart the shock to the structure. Before these devices can be implemented in practice, there are many issues that need to be understood with respect to their performance and modelling. Moreover, a comparative assessment between popular retrofit options employing isolation systems needs to be undertaken to verify and provide a benchmark to assess their performance. The Mississippi River Bridge near Ottawa is chosen as a test structure to conduct this study. This bridge already contains an advanced isolation system, and has an extensive documentation available for modelling and verification. Various retrofit options will be studied and compared with the existing isolation design for this bridge. In all cases, the effect of soil-structure interaction is included. A comprehensive set of performance indices are used to evaluate the performance of various retrofit options. All the models are constructed in the open source software, OpenSees. The research demonstrates that the proposed approach is a viable retrofit method for highway bridges. Moreover, compared to advanced isolation systems, retrofit using elastomeric bearings with viscous dampers was successful on transferring lower loads to the substructure, and resulted in lower superstructure displacements. Though this study involved one bridge, it has provided a computational test bed to perform further studies and has provided valuable insight into the modeling and performance of retrofit solutions.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 222-229). Available also in a digital version from Dissertation Abstracts.

Thesis--M. Phil., University of Hong Kong, 1984.

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