This paper presents a comprehensive critical review of technologies used in the development of fibre optic shape sensors (FOSSs). Their operation is based on multi-dimensional bend measurements using a series of fibre optic sensors. Optical fibre sensors have experienced tremendous growth from simple bend sensors in 1980s to full three-dimensional FOSSs using multicore fibres in recent years. Following a short review of conventional contact-based shape sensor technologies, the evolution trend and sensing principles of FOSSs are presented. This paper identifies the major optical fibre technologies used for shape sensing and provides an account of the challenges and emerging applications of FOSSs in various industries such as medical robotics, industrial robotics, aerospace and mining industry.

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Coal Mine Methane (CMM) drainage via adopting in-seam horizontal boreholes is an effective way to decrease ventilation cost and production delay, ensure mining safety, reduce greenhouse gas emissions and increase the supply of energy resource.Ventilation air leakage into borehole, however, occurs frequently, which decreases the methane-drainage efficiency. Despite extensive anti-leakage method investigations, a very few studies have been focused on spraying air-proof materials on the roadway rib and optimizing borehole sealing along the borehole, along with taking the effects of sequential excavations of roadway and borehole into account. In this paper, based on data of a real coal mine, a fully coupled mathematical model was developed by incorporating coal permeability with coal mechanical properties and gas adsorption/desorption and was then implemented into a Finite Element software. This numerical simulation was used to analyse transient stress and dynamic air-leakage flow fields around the drainage borehole. Simulation results indicate that: (1) Four stress areas (І to IV) exist around the roadway based on different relief status of the tri-axial stress, and stress distributions around the borehole in those four areas are different from each other; (2) Based on different air-leakage degrees, on the roadway rib, there are four air-leakage levels around borehole. Meanwhile, there are four leakage areas along the borehole: FAA, SAA, HAA and VAA, and the optimal sealing length should be over 17m (exceeding HAA) to prevent air leakage. Air-leakage results in (2) are verified mutually with the mechanics outcomes in (1). Meanwhile, real data obtained from field experiments is introduced to validate the simulation results. All those outcomes can allow for the optimal design of the spraying area and order and borehole sealing, thus provide scientific basis for an integrated anti-air-leakage method including spraying air-proof materials on the roadway wall and sealing borehole effectively, to prevent ventilation air leakage and maximize methane drainage performance.

ABSTRACT:Creep is a time-dependent deformation that affects coal permeability and should be considered in the prediction of Coalbed Methane (CBM) production. This study experimentally characterises and quantifies the impact of creep on coal permeability. The experiments were conducted on a bituminous coal sample, excavated from Bowen Basin, Australia, using a triaxial gas rig equipped with strain and displacement transducers. Two different types of gasses (helium and methane) were injected into the sample under various stress and pore pressure conditions. It was found that for the experiments with helium, creep caused permanent partial closure of cleats and pathways under constant effective stress, and hence a reduction in permeability. Under hydrostatic stress only, a Residual Deformation Ratio (RDR) of 14.1% and a Permeability Loss Ratio (PLR) of 71% were found following the removal of the axial load. This can be due to the damage to coal microstructure along with closure of cleats. For the experiments with methane, coal experienced an instantaneous elastic deformation, at the onset of pore pressure depletion, followed by consolidation and matrix shrinkage. Then, creep occurred when gas desorption ceased. A total permeability loss of 26% was achieved due to an increase of 1.91 MPa in effective stress caused by gas desorption. In addition, the model previously developed by authors was validated against the experimental permeability data. A good agreement was found between the model-predicted permeability data and the experimental permeability data, particularly for higher pore pressure ranges.Keywords: Coal permeability; creep; consolidation; triaxial test; gas desorption

This is the second paper of a series authored by a collaboration of international researchers. It develops taxonomy for computer-based virtual reality simulators of relevance to the mining industry. A summary is presented of simulator types implemented in the industry, and continuums are used to explain concepts and issues that affect simulator development and integration. The paper classifies simulators and demonstrates that there are potentially many simulator formats still to be realised and implemented by the mining industry. Simulator issues that are often overlooked such as human factors, cognitive load and development costs and their impact on the development of sustainable simulator technologies are considered in some detail. Barriers to development and integration are mentioned, and the need for industry to engage with university-level research and develop a uniform and integrated approach are discussed. Finally, a brief case study is presented and conclusions are drawn about the current status and sustainability of simulator development in the mining industry.