In this paper,the advantage of using numerical models with the strength reduction method(SRM) to evaluate entry stability in complex multiple-seam conditions is demonstrated.A coal mine under variable topography from ...In this paper,the advantage of using numerical models with the strength reduction method(SRM) to evaluate entry stability in complex multiple-seam conditions is demonstrated.A coal mine under variable topography from the Central Appalachian region is used as a case study.At this mine,unexpected roof conditions were encountered during development below previously mined panels.Stress mapping and observation of ground conditions were used to quantify the success of entry support systems in three room-and-pillar panels.Numerical model analyses were initially conducted to estimate the stresses induced by the multiple-seam mining at the locations of the affected entries.The SRM was used to quantify the stability factor of the supported roof of the entries at selected locations.The SRM-calculated stability factors were compared with observations made during the site visits,and the results demonstrate that the SRM adequately identifies the unexpected roof conditions in this complex case.It is concluded that the SRM can be used to effectively evaluate the likely success of roof supports and the stability condition of entries in coal mines.展开更多
Phase is a fundamental resource for optical imaging but cannot be directly observed with intensity measurements.The existing methods to quantify a phase distribution rely on complex devices and structures and lead to ...Phase is a fundamental resource for optical imaging but cannot be directly observed with intensity measurements.The existing methods to quantify a phase distribution rely on complex devices and structures and lead to difficulties of optical alignment and adjustment.We experimentally demonstrate a phase mining method based on the so-called adjustable spatial differentiation,by analyzing the polarization of light reflection from a single planar dielectric interface.Introducing an adjustable bias,we create a virtual light source to render the measured images with a shadow-cast effect.From the virtual shadowed images,we can further recover the phase distribution of a transparent object with the accuracy of 0.05λRMS.Without any dependence on wavelength or material dispersion,this method directly stems from the intrinsic properties of light and can be generally extended to a broad frequency range.展开更多
On March 16,the commissioning ceremony of the Pulang Copper Mine phase I mining and dressing project was held as scheduled.The Pulang Copper Mine,located in the 3,500-meter altitude snowy plateau of Shangri-la
文摘In this paper,the advantage of using numerical models with the strength reduction method(SRM) to evaluate entry stability in complex multiple-seam conditions is demonstrated.A coal mine under variable topography from the Central Appalachian region is used as a case study.At this mine,unexpected roof conditions were encountered during development below previously mined panels.Stress mapping and observation of ground conditions were used to quantify the success of entry support systems in three room-and-pillar panels.Numerical model analyses were initially conducted to estimate the stresses induced by the multiple-seam mining at the locations of the affected entries.The SRM was used to quantify the stability factor of the supported roof of the entries at selected locations.The SRM-calculated stability factors were compared with observations made during the site visits,and the results demonstrate that the SRM adequately identifies the unexpected roof conditions in this complex case.It is concluded that the SRM can be used to effectively evaluate the likely success of roof supports and the stability condition of entries in coal mines.
基金The authors acknowledge funding through the National Natural Science Foundation of China(NSFC Grants Nos.91850108 and 61675179)the National Key Research and Development Program of China(Grant No.2017YFA0205700)the Open Foundation of the State Key Laboratory of Modern Optical Instrumentation,and the Open Research Program of Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province.Z.R.,T.Z.,and J.H.are named inventors on a number of related patent applications related to this work。
文摘Phase is a fundamental resource for optical imaging but cannot be directly observed with intensity measurements.The existing methods to quantify a phase distribution rely on complex devices and structures and lead to difficulties of optical alignment and adjustment.We experimentally demonstrate a phase mining method based on the so-called adjustable spatial differentiation,by analyzing the polarization of light reflection from a single planar dielectric interface.Introducing an adjustable bias,we create a virtual light source to render the measured images with a shadow-cast effect.From the virtual shadowed images,we can further recover the phase distribution of a transparent object with the accuracy of 0.05λRMS.Without any dependence on wavelength or material dispersion,this method directly stems from the intrinsic properties of light and can be generally extended to a broad frequency range.
文摘On March 16,the commissioning ceremony of the Pulang Copper Mine phase I mining and dressing project was held as scheduled.The Pulang Copper Mine,located in the 3,500-meter altitude snowy plateau of Shangri-la