A series of experiments were conducted to invesdgate high pressure water jet assisted coal cutting. The research was sponsored by British Coal and carried out in the Department of Mining Engineering at the University of Newcastle upon Tyne. Two coals were tested: a black, coherent, anthracite; and a heavily cleated, friable, dull coloured bituminous coal. The tests modelled as closely as possible a vane pick on a two start shearer drum. The experiment was performed on a modified 50 tonne linear cutting rig at a speed of I. Im/s, using jet pressures of 35MPa, 70MPa, and 105MPa at different flow rates. A 75kW double acting intensifier type pump supplied the high pressure water for the jet. A relieved cutting mode was adopted with a line spacing of 70mm, and a 30mm nominal depth of cut. An actual production cutting tool (heavy duty 75mm radial with a HW tip) cut the coal in both the sharp and blunt states. Additional tests were also performed by pre-slotting the coal with a water jet before cutting it and by examining the effect of varying the lead and offset distances on the parameters measured below. Parameters measured were the cutting forces in three orthogonal directions; the breakout patterns; and the coal size distribution. The coal yields and specific energies were calculated from the experimental data. Both coals achieved benefit from jet assistance but at different pressures depending upon the coal type and tool wear. The breakout pattern differed between the two coals but generally fracture occurred along the major cleat planes. Both coals were easier to cut when the major cleat was orientated in the horizontal plane rather than in the vertical plane. Specific energy increased linearly with jet power. In most cases the quantity of fine coal (-0.5mm) produced decreased with jet assistance.

published_or_final_version / Computer Science / Master / Master of Philosophy

Multi-faceted data contains different types of objects and relationships between them. With rapid growth of web-based services, multi-faceted data are increasing (e.g. Flickr, Yago, IMDB), which offers us richer information to infer users’ preferences and provide them better services. In this study, we look at two types of multi-faceted data: social tagging system and heterogeneous information network and how to improve service such as resources retrieving and classification on them. In social tagging systems, resources such as images and videos are annotated with descriptive words called tags. It has been shown that tag-based resource searching and retrieval is much more effective than content-based retrieval. With the advances in mobile technology, many resources are also geo-tagged with location information. We observe that a traditional tag (word) can carry different semantics at different locations. We study how location information can be used to help distinguish the different semantics of a resource’s tags and thus to improve retrieval accuracy. Given a search query, we propose a location-partitioning method that partitions all locations into regions such that the user query carries distinguishing semantics in each region. Based on the identified regions, we utilize location information in estimating the ranking scores of resources for the given query. These ranking scores are learned using the Bayesian Personalized Ranking (BPR) framework. Two algorithms, namely, LTD and LPITF, which apply Tucker Decomposition and Pairwise Interaction Tensor Factorization, respectively for modeling the ranking score tensor are proposed. Through experiments on real datasets, we show that LTD and LPITF outperform other tag-based resource retrieval methods. A heterogeneous information network (HIN) is used to model objects of different types and their relationships. Meta-paths are sequences of object types. They are used to represent complex relationships between objects beyond what links in a homogeneous network capture. We study the problem of classifying objects in an HIN. We propose class-level meta-paths and study how they can be used to (1) build more accurate classifiers and (2) improve active learning in identifying objects for which training labels should be obtained. We show that class-level meta-paths and object classification exhibit interesting synergy. Our experimental results show that the use of class-level meta-paths results in very effective active learning and good classification performance in HINs. / published_or_final_version / Computer Science / Master / Master of Philosophy

published_or_final_version / Computer Science and Information Systems / Master / Master of Philosophy

Rock is a very heterogeneous material, containing structural weakness at all scales. These weaknesses include grain boundaries, pores, and cracks on the small scale, and joints, faults, and bedding planes on the large scale. Nonlinear rock deformation in the low-temperature, low-confinement regime is due primarily to the growth of cracks from these weaknesses and the coalescence of cracks to form macroscopic structural features. Another important aspect of rock deformation and failure is the statistical distribution of weaknesses in the initial microstructure. Borehole breakout is the process by which portions of a borehole wall fracture or spall when subjected to compressive stresses. Studies of borehole breakout in the past twenty years include experiments, field studies, and numerical modeling. With regards to the numerical modeling of borehole breakout, the rock surrounding the borehole is considered as a nonlinear continuum material in most of the previous approaches. Experiments and field studies, however, have shown that the heterogeneous and discontinuous nature of rock has a strong impact on the mechanics of borehole breakout. This dissertation describes a numerical model that has been developed to simulate the damage of rock and the corresponding non-linear stress-strain behavior, and also the progression of borehole breakout in heterogeneous and discontinuous rock by mixed mode crack growth, interaction, and coalescence. The rock is simulated as an elastic material containing a random distribution of cracks. As compressive load is applied, the initial cracks grow, interact, and coalesce to form macroscopic fractures. The numerical model was developed by making a series of modifications to the displacement discontinuity code of Crouch and Starfield (Crouch & Starfield, 1983). The most important modifications include modifying the boundary element for the calculation of stress intensity factors, adding Coulomb friction for closed portions of cracks, adding a crack generator, and adding an algorithm for crack coalescence. The numerical model is used to simulate the non-linear deformation and the progression of breakout in Westerly granite, and the results are realistic.

The objective of this investigation is to experimentally determine the effectiveness of fracture sealing in welded tuff using ordinary portland cement and microfine cement grouts. Fracture grouting will most likely be used to seal fractures intersecting high level nuclear waste repositories. Fractures are potential pathways for the migration of radionuclides. Laboratory experiments have been performed on seventeen tuff cylinders. (1) tension induced cracks, (2) natural and, (3) sawcut surfaces serve as fractures. Prior to grouting, the hydraulic conductivity of the intact rock and that of the fractures themselves are measured under a range of normal stresses. Grouts are injected through axial boreholes at pressures of 0.3 to 4.1 MPa while holding fractures under a constant normal stress. Five grout formulations have been selected. Minor amounts of bentonite (0 to 5 percent by weight) have been added to these grouts to increase stability. Water to cement ratios range from 0.45 to 1.0. Permeameter testing of grouted fractures is used to evaluate the effectiveness of fracture grouting.

The objective of this investigation was to experimentally determine the variation in the flow characteristics of tactite copper ores during the leaching process. The laboratory work involved estimation of porosity and permeability of cores before leaching, and after various intervals of leaching. The tests were carried out using specimens of diameter 1.5 and 4.0 inches, prepared from boulders obtained from the Cyprus Casa Grande mine. A solution containing about 25 grams of sulfuric acid per liter was used as the lixiviant. Porosity was determined using the water saturation method. The permeability was estimated using either helium or water with the specimens stressed triaxially to simulate in situ conditions. The rate of copper recovery from the specimen during the leaching process was also determined by estimating the copper content in the solution used for leaching. The results indicate that the permeability and porosity of the specimens increased with leaching, but both tend to remain constant after most of the soluble material in the core was dissolved. The rate of copper recovery was high initially but dropped as leaching progressed and the copper in the specimen was depleted.

Library and information services in corporations, schools, universities, and communities capture information about their users, circulation history, resources in the collection, and search patterns (Koenig, 1985). Unfortunately, few libraries have taken advantage of these data as a way to improve customer service, manage acquisition budgets, or influence strategic decision-making about uses of information in their organizations. In this chapter, we present a global view of the data generated in libraries and the variety of decisions that those data can inform. We describe ways in which library and information managers can use data mining in their libraries, i.e. bibliomining, to understand patterns of behavior among library users and staff members and patterns of information resource use throughout the institution. The chapter examines data sources and possible applications of data mining techniques and explores the legal and ethical implications of data mining in libraries.

No description available.

The history of mine backfill shows that in the past, considerable improvements in backfill-reliant mining technology were made when new fill systems were introduced. The present trend in mine backfill technology is towards the use of high-density fill systems. Tight filling and void reduction have also become essential requirements in engineering design of mines to ensure global stability. High-density fills have a low moisture content and are more competent products requiring less binder and time for stabilization, compared to conventional hydraulic backfill. Cemented rockfill and tailings/sand paste fills are two familiar high-density backfill systems in current use. In future there could be a high demand for low porosity high-density fills, as mines go deeper and ground stresses increase. / This study was an original attempt to investigate the characteristics and property of high-density composite fill systems. Composite fills are made up of derivatives of waste rock, tailings, sand and metallurgical by-products. Composite fills represent the future direction of backfill technology. As mines go deeper, the ore could be processed underground and the waste rock and tailings combined together to form a low-porosity competent fill product. The application of composite fill systems will also increase the material available for backfilling, provide more flexibility in backfill mix design and produce competent fill systems for ground support. It will also benefit the underground mine environment through effective utilization of mine wastes. / The fundamental basis of the work required the study and understanding of the characteristics and properties of cemented rockfill and paste backfill. The effects of sand addition to fine tailings as a means of reducing porosity and improving the mechanical properties of the fill product were also investigated. Additionally, a new concept of backfill, namely, Composite-Aggregate Paste (CAP) that consists of a mixture of fine tailings and graded coarse aggregates was introduced and the material properties were investigated.