The physical quantity of the square of tensile strength over Young’s modulus has been proposed as a criterion of comminution of rock by Oka and Majima. The value was determined for five different rocks, measuring tensile strength and Young's modulus. The testing method used to determine both rock properties was a point-load tensile strength test and measurement of propagation velocity of P-wave. In order to verify the applicability of the criterion thus obtained, the drop-weight impact test and ball mill grinding were carried out using the identical specimen used for tensile strength and Young's modulus test. The experimental result was obtained that the square of tensile strength is more applicable than the square of tensile strength over Young's modulus. In chapter 2, grinding tests were performed with a 12 inch batch mill. A torque meter was installed to estimate the energy consumption.necessary to achieve size reduction. From the torque measurement, the required torque for the mill turning remained almost constant regardless of the material being ground. A new concept, Energy Index, was introduced to evaluate grinding results and to study grinding problems. For each rock sample tested, the energy index was determined from torque measurements and the quantity of the products. It was found the energy index has a linear relationship with Bond work index under selected grinding condition. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

­^¤åºK­n The purpose of this thesis is to propose the rules for designing a grinding system with nano-order of relative vibration. Such a system is aimed to perform the ductile-regime grinding for brittle materials. The study will examine the influence of the structure stiffness, damping, and mass of the grinding system on the relative vibration between grinding wheel and work. Accordingly, the design rules will be proposed. To analyze the relative vibration, the radial and axial models for a grinding system were built. The trends of relative vibration between grinding wheel and work were then analyzed under three kinds of vibration sources. Because of the nonlinearity of system equations, the 4th order Runge-Kutta numerical method was used to calculate the solutions. In addition, the genetic algorithm was used to search an optimum design. From the analysis, several design rules for grinding system, which can minimize the relative vibration, were proposed.

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Production of micro-scale components is an important emergent field. One underdeveloped area is the production of micro-scale 3D surfaces, which has important applications in micro-optics and fibre optic sensors. One particular application is the production of micro-lenses. With scales of less than 200 ??m these lenses can improve light coupling efficiencies in micro-optic systems. However, current lens production techniques have limitations in accuracy and versatility. Creating these surfaces through mechanical micro-grinding has the potential to improve the precision and variety of profiles that can be produced, thus improving transmission efficiencies and leading to new applications. This work presents a novel micro-grinding method for the production of microscale asymmetric, symmetric and axisymmetric curved components from brittle materials such as glasses. A specialised micro-grinding machine and machining system has been designed, constructed and successfully tested and is presented here. This system is capable of producing complex profiles directly on the tips of optical fibre workpieces. A five degree of freedom centring system is presented that can align and rotate these workpieces about a precision axis, enabling axisymmetric grinding. A machine vision system, utilising a microscope lens system and sub-pixel localisation techniques, is used to provide feedback for the process, image processing techniques are presented which are shown to have a sensing resolution of 300 nm. Using these systems, workpieces are centred to within 500 nm. Tools are mounted on nanometre precise motion stages and motion and infeed are controlled. Tooling configurations with flat and tangential grinding surfaces are presented along with control and path generation algorithms. The capabilities and shortcomings of each are presented along with methods to predict appropriate feed rates based on experimental data. Both asymmetric and axisymmetric flat and curved micro-profiles have been produced on the tips of optical fibres using this system. These are presented and analysed and show that the system, as described, is capable of producing high quality micro-scale components with submicron dimensional accuracy and nanometric surface quality. The advantages of this technique are compared with other processes and discussed. Further development of the system and technique are also considered.

For the requirements of high-speed signal transmission has been increasing, the fiber array in the communication system has a lot of advantages which can not be replaced. But the loss of coupling efficiency is a difficult problem as the distance of communication is getting longer and longer. For the sake of solving this problem, the system needs to use optic amplifier for enlarging the coupling efficiency in every long distance. The receiver can receive the correct signal by using optic amplifier. In order to reduce the using amount of optic amplifier for decreasing the cost, producing the fiber array with high coupling efficiency can reach the goal. This paper chooses quadrangular-pyramid-shaped fiber endface (QPSFE) which has better coupling efficiency than flattened-end fiber to research. Among those different manufacturing methods and different precision for fiber array packaging, the research chooses the method of grinding to manufacture the shape of surface. The research can raise the accuracy of manufacture for increasing the coupling efficiency of QPSFE by external equipments.

Production of micro-scale components is an important emergent field. One underdeveloped area is the production of micro-scale 3D surfaces, which has important applications in micro-optics and fibre optic sensors. One particular application is the production of micro-lenses. With scales of less than 200 ??m these lenses can improve light coupling efficiencies in micro-optic systems. However, current lens production techniques have limitations in accuracy and versatility. Creating these surfaces through mechanical micro-grinding has the potential to improve the precision and variety of profiles that can be produced, thus improving transmission efficiencies and leading to new applications. This work presents a novel micro-grinding method for the production of microscale asymmetric, symmetric and axisymmetric curved components from brittle materials such as glasses. A specialised micro-grinding machine and machining system has been designed, constructed and successfully tested and is presented here. This system is capable of producing complex profiles directly on the tips of optical fibre workpieces. A five degree of freedom centring system is presented that can align and rotate these workpieces about a precision axis, enabling axisymmetric grinding. A machine vision system, utilising a microscope lens system and sub-pixel localisation techniques, is used to provide feedback for the process, image processing techniques are presented which are shown to have a sensing resolution of 300 nm. Using these systems, workpieces are centred to within 500 nm. Tools are mounted on nanometre precise motion stages and motion and infeed are controlled. Tooling configurations with flat and tangential grinding surfaces are presented along with control and path generation algorithms. The capabilities and shortcomings of each are presented along with methods to predict appropriate feed rates based on experimental data. Both asymmetric and axisymmetric flat and curved micro-profiles have been produced on the tips of optical fibres using this system. These are presented and analysed and show that the system, as described, is capable of producing high quality micro-scale components with submicron dimensional accuracy and nanometric surface quality. The advantages of this technique are compared with other processes and discussed. Further development of the system and technique are also considered.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references.

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QC 351 A7 no. 71 / Generalized ray tracing is a method of calculating the principal curvatures and directions of the wavefront associated with a ray as it is traced through an optical system. The results of such a ray trace provide important information about the structure of the image and have immediate application to lens design and image analysis. The caustic surface formed by an optical system can be easily determined from the results of a generalized ray trace. An examination of several caustic surfaces formed by different optical systems provides valuable information about the relative quality of the images and indicates some of the advantages of the generalized ray tracing method.