In open pit mining,uncontrolled block instabilities have serious social,economic and regulatory consequences,such as casualties,disruption of operation and increased regulation difficulties.For this reason,bench face ...In open pit mining,uncontrolled block instabilities have serious social,economic and regulatory consequences,such as casualties,disruption of operation and increased regulation difficulties.For this reason,bench face angle,as one of the controlling parameters associated with block instabilities,should be carefully designed for sustainable mining.This study introduces a discrete fracture network(DFN)-based probabilistic block theory approach for the fast design of the bench face angle.A major advantage is the explicit incorporation of discontinuity size and spatial distribution in the procedure of key blocks testing.The proposed approach was applied to a granite mine in China.First,DFN models were generated from a multi-step modeling procedure to simulate the complex structural characteristics of pit slopes.Then,a modified key blocks searching method was applied to the slope faces modeled,and a cumulative probability of failure was obtained for each sector.Finally,a bench face angle was determined commensurate with an acceptable risk level of stability.The simulation results have shown that the number of hazardous traces exposed on the slope face can be significantly reduced when the suggested bench face angle is adopted,indicating an extremely low risk of uncontrolled block instabilities.展开更多
Members in the family Herpesviridae share a common architecture:the outer envelope,the inner nucleocapsid and the in-between tegument.There are three types of capsids,A-,B-and C-capsids,which are matured from the proc...Members in the family Herpesviridae share a common architecture:the outer envelope,the inner nucleocapsid and the in-between tegument.There are three types of capsids,A-,B-and C-capsids,which are matured from the procapsid.The procapsid is assembled in the host cell nucleus where the viral dsDNA genome is packaged.The viral genome is driven into the procapsid by the terminase through the portal,which locates at a unique vertex of the icosahedral capsid(Heming et al.,2017).The A-capsid is empty and is believed to be resulted from unsuccessfully packaging of viral genome.B-capsid contains the scaffold similar to that of the procapsid and is likely resulted from failed initiation of viral DNA packaging.展开更多
The safety of a space station under normal and abnormal conditions can be ensured only by comprehensively identifying various hazards of the space station during its whole mission cycle and formulating control measure...The safety of a space station under normal and abnormal conditions can be ensured only by comprehensively identifying various hazards of the space station during its whole mission cycle and formulating control measures against each hazard.This paper describes the safety design process of the China Space Station,as well as detailed safety design measures for general hazards,fault hazards,dangerous events,and critical missions,so as to achieve safety goals as far as possible under the circumstances of limited resources and transportation capacity of the space station.The key work of safety design includes identification of hazard sources and dangerous events,formulation of safety control measures,and design of safety safeguard measures.Identification of hazards and hazardous events is based on both defined content in design schemes and previous on-orbit flight experience of manned spacecraft.The formulated safety control measures are based on analyzing each hazard to determine key links of safety control and formulate corresponding control measures for effective hazard control under minimum resource cost.In the case of a serious failure,the space station can remain safe within a certain time by its autonomous hazard disposal.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.42102313 and 52104125)the Fundamental Research Funds for the Central Universities(Grant No.B240201094).
文摘In open pit mining,uncontrolled block instabilities have serious social,economic and regulatory consequences,such as casualties,disruption of operation and increased regulation difficulties.For this reason,bench face angle,as one of the controlling parameters associated with block instabilities,should be carefully designed for sustainable mining.This study introduces a discrete fracture network(DFN)-based probabilistic block theory approach for the fast design of the bench face angle.A major advantage is the explicit incorporation of discontinuity size and spatial distribution in the procedure of key blocks testing.The proposed approach was applied to a granite mine in China.First,DFN models were generated from a multi-step modeling procedure to simulate the complex structural characteristics of pit slopes.Then,a modified key blocks searching method was applied to the slope faces modeled,and a cumulative probability of failure was obtained for each sector.Finally,a bench face angle was determined commensurate with an acceptable risk level of stability.The simulation results have shown that the number of hazardous traces exposed on the slope face can be significantly reduced when the suggested bench face angle is adopted,indicating an extremely low risk of uncontrolled block instabilities.
文摘Members in the family Herpesviridae share a common architecture:the outer envelope,the inner nucleocapsid and the in-between tegument.There are three types of capsids,A-,B-and C-capsids,which are matured from the procapsid.The procapsid is assembled in the host cell nucleus where the viral dsDNA genome is packaged.The viral genome is driven into the procapsid by the terminase through the portal,which locates at a unique vertex of the icosahedral capsid(Heming et al.,2017).The A-capsid is empty and is believed to be resulted from unsuccessfully packaging of viral genome.B-capsid contains the scaffold similar to that of the procapsid and is likely resulted from failed initiation of viral DNA packaging.
基金supported by the Chinese manned space-flight program.
文摘The safety of a space station under normal and abnormal conditions can be ensured only by comprehensively identifying various hazards of the space station during its whole mission cycle and formulating control measures against each hazard.This paper describes the safety design process of the China Space Station,as well as detailed safety design measures for general hazards,fault hazards,dangerous events,and critical missions,so as to achieve safety goals as far as possible under the circumstances of limited resources and transportation capacity of the space station.The key work of safety design includes identification of hazard sources and dangerous events,formulation of safety control measures,and design of safety safeguard measures.Identification of hazards and hazardous events is based on both defined content in design schemes and previous on-orbit flight experience of manned spacecraft.The formulated safety control measures are based on analyzing each hazard to determine key links of safety control and formulate corresponding control measures for effective hazard control under minimum resource cost.In the case of a serious failure,the space station can remain safe within a certain time by its autonomous hazard disposal.
