Longwall mining continues to remain the most efficient method for underground coal recovery. A key aspect in achieving safe and productive longwall mining is to ensure that the shearer is always correctly positioned w...Longwall mining continues to remain the most efficient method for underground coal recovery. A key aspect in achieving safe and productive longwall mining is to ensure that the shearer is always correctly positioned within the coal seam. At present, this machine positioning task is the role of longwall personnel who must simultaneously monitor the longwall coal face and the shearer's cutting drum position to infer the geological trends of the coal seam. This is a labour intensive task which has negative impacts on the consistency and quality of coal production. As a solution to this problem, this paper presents a sensing method to automatically track geological coal seam features on the longwall face, known as marker bands, using thermal infrared imaging. These non-visible marker bands are geological features that link strongly to the horizontal trends present in layered coal seams. Tracking these line-like features allows the generation of a vertical datum that can be used to maintain the shearer in a position for optimal coal extraction. Details on the theory of thermal infrared imaging are given, as well as practical aspects associated with machine-based implementation underground. The feature detection and tracking tasks are given with real measurements to demonstrate the efficacy of the approach. The outcome is important as it represents a new selective mining capability to help address a long-standing limitation in longwall mining operations.展开更多
When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is...When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is much slower. This paper analyses the DC component of fault branch, and has found it is much bigger than that of the normal branches in transient state. All the simulation results obtained from three compensation types, different fault time and different wave cycles show that the DC component of fault branch is much higher than that of those normal branches. These results verify the effectiveness of taking the DC component as the method of fault line selection in the arc suppression coil grounding system.展开更多
Background Transradial access for coronary catheterization is more technically challenging compared to the traditional transfemoral approach and radial access failure is quite common. The aim of this study is to descr...Background Transradial access for coronary catheterization is more technically challenging compared to the traditional transfemoral approach and radial access failure is quite common. The aim of this study is to describe the additional steps after initial radial access site failure in a high specialized forearm approach center. Methods A retrospective evaluation of all coronary catheterizations performed in our Department between January 2016 and December 2016 was performed, with focus on arterial access. Results One thousand three hundred forty six procedures were evaluated. The initial access site used was right radial [1173 procedures （87.1%）], left radial [120 procedures （8.9%）], fight ulnar [7 procedures （0.5%）], left ulnar [40 procedures （2.9%）] and femoral approach [6 procedures （0.4%）]. Radial artery can- nulation failure was observed in 37 procedures （2.9% of 1293 procedures with initial radial approach）. Failure of procedure completion after successful radial sheath insertion was observed in 46 procedures （3.6%）. The alternative access site after initial radial approach failure was contralateral radial [43 procedures （51.8%）], ipsilateral ulnar [22 procedures （26.5%）, contralateral ulnar [12 patients （14.5%）] and femoral approach [6 procedures （7.2%）]. Conclusion Forearm arteries can be used as alternative access site after initial radial approach failure in order to reduce the use of femoral approach during cardiac catheterization.展开更多
Nuclear engineering belongs to significant project;there is higher requirement on sitings.The study has discussed basic factors of selecting sites,anti-seismic research on sitings including the seismic ground motion,p...Nuclear engineering belongs to significant project;there is higher requirement on sitings.The study has discussed basic factors of selecting sites,anti-seismic research on sitings including the seismic ground motion,probability methods of seismic hazard analysis as well as interaction about structure and foundation,meanwhile provide the reason for nuclear engineering selecting sites.展开更多
基金the Australian Coal Association Research Program(ACARP)for their invaluable support that enabled new research and development into longwall shearer automation
文摘Longwall mining continues to remain the most efficient method for underground coal recovery. A key aspect in achieving safe and productive longwall mining is to ensure that the shearer is always correctly positioned within the coal seam. At present, this machine positioning task is the role of longwall personnel who must simultaneously monitor the longwall coal face and the shearer's cutting drum position to infer the geological trends of the coal seam. This is a labour intensive task which has negative impacts on the consistency and quality of coal production. As a solution to this problem, this paper presents a sensing method to automatically track geological coal seam features on the longwall face, known as marker bands, using thermal infrared imaging. These non-visible marker bands are geological features that link strongly to the horizontal trends present in layered coal seams. Tracking these line-like features allows the generation of a vertical datum that can be used to maintain the shearer in a position for optimal coal extraction. Details on the theory of thermal infrared imaging are given, as well as practical aspects associated with machine-based implementation underground. The feature detection and tracking tasks are given with real measurements to demonstrate the efficacy of the approach. The outcome is important as it represents a new selective mining capability to help address a long-standing limitation in longwall mining operations.
文摘When single phase earth fault occurs in the arc suppression coil grounding system, the amplitude of the transient capacitance current is high and decays fast, but the attenuation of the transient inductance current is much slower. This paper analyses the DC component of fault branch, and has found it is much bigger than that of the normal branches in transient state. All the simulation results obtained from three compensation types, different fault time and different wave cycles show that the DC component of fault branch is much higher than that of those normal branches. These results verify the effectiveness of taking the DC component as the method of fault line selection in the arc suppression coil grounding system.
文摘Background Transradial access for coronary catheterization is more technically challenging compared to the traditional transfemoral approach and radial access failure is quite common. The aim of this study is to describe the additional steps after initial radial access site failure in a high specialized forearm approach center. Methods A retrospective evaluation of all coronary catheterizations performed in our Department between January 2016 and December 2016 was performed, with focus on arterial access. Results One thousand three hundred forty six procedures were evaluated. The initial access site used was right radial [1173 procedures （87.1%）], left radial [120 procedures （8.9%）], fight ulnar [7 procedures （0.5%）], left ulnar [40 procedures （2.9%）] and femoral approach [6 procedures （0.4%）]. Radial artery can- nulation failure was observed in 37 procedures （2.9% of 1293 procedures with initial radial approach）. Failure of procedure completion after successful radial sheath insertion was observed in 46 procedures （3.6%）. The alternative access site after initial radial approach failure was contralateral radial [43 procedures （51.8%）], ipsilateral ulnar [22 procedures （26.5%）, contralateral ulnar [12 patients （14.5%）] and femoral approach [6 procedures （7.2%）]. Conclusion Forearm arteries can be used as alternative access site after initial radial approach failure in order to reduce the use of femoral approach during cardiac catheterization.
文摘Nuclear engineering belongs to significant project;there is higher requirement on sitings.The study has discussed basic factors of selecting sites,anti-seismic research on sitings including the seismic ground motion,probability methods of seismic hazard analysis as well as interaction about structure and foundation,meanwhile provide the reason for nuclear engineering selecting sites.
