The exposed surface of the dry salt lake basin contains a large number of extremely fine lightweight saline-alkali(mixed)dust and clay dust.It is extremely easy to dust and since saline-alkali lake is low-lying and it...The exposed surface of the dry salt lake basin contains a large number of extremely fine lightweight saline-alkali(mixed)dust and clay dust.It is extremely easy to dust and since saline-alkali lake is low-lying and its temperature展开更多
At a fully mechanized working face of a coal mine as prototype,we investigated,by simulation,the flow field and dust distribution during the process of its isolation by a curtain of air,using the CFD software, Fluent....At a fully mechanized working face of a coal mine as prototype,we investigated,by simulation,the flow field and dust distribution during the process of its isolation by a curtain of air,using the CFD software, Fluent.The results show that the air curtain installed on the shearer can effectively prevent the dust （especially the respirable dust）from diffusing into the work area of the operator,reducing the dust concentration on the side of the operator and greatly improving his working environment.The field application of the air curtain shows that the dust-isolation effect of an air curtain is quite noticeable.The isolation efficiency for respiratory dust is over 70%and,as well,it has good dust-isolation effect for nonrespiratory dust.The air curtain is a useful way to resolve the problem of dust-isolation at a fully mechanized working face.It has a practical background elsewhere with more extensive applications.展开更多
Observations imply that long ＂y-ray bursts （GRBs） originate from the explo- sions of massive stars, therefore they may occur in the molecular clouds where their progenitors were born. We show that the prompt optica...Observations imply that long ＂y-ray bursts （GRBs） originate from the explo- sions of massive stars, therefore they may occur in the molecular clouds where their progenitors were born. We show that the prompt optical-UV emission from GRBs may be delayed due to dust extinction, which can explain the observed optical delayed on- set and fast rise in GRB 080319B well. The density and the size of the molecular cloud around GRB 080319B are roughly constrained to be ~ 103 cm-z and ~ 8 pc, respectively. We also investigate other GRBs with prompt optical-UV data, and find similar values of the densities and sizes of the local molecular clouds. Future obser- vations of prompt optical-UV emission from GRBs on a timescale of subseconds, e.g. by UFFO-Pathfinder and SVOM-GWAC, will provide more evidence and probes of the local environments of GRBs.展开更多
文摘The exposed surface of the dry salt lake basin contains a large number of extremely fine lightweight saline-alkali(mixed)dust and clay dust.It is extremely easy to dust and since saline-alkali lake is low-lying and its temperature
基金Financial support for this work,provided by the National Natural Science Foundation of China(No.50974060)the State Safety Production Science and Technology Development Plan (No.06-396)
文摘At a fully mechanized working face of a coal mine as prototype,we investigated,by simulation,the flow field and dust distribution during the process of its isolation by a curtain of air,using the CFD software, Fluent.The results show that the air curtain installed on the shearer can effectively prevent the dust （especially the respirable dust）from diffusing into the work area of the operator,reducing the dust concentration on the side of the operator and greatly improving his working environment.The field application of the air curtain shows that the dust-isolation effect of an air curtain is quite noticeable.The isolation efficiency for respiratory dust is over 70%and,as well,it has good dust-isolation effect for nonrespiratory dust.The air curtain is a useful way to resolve the problem of dust-isolation at a fully mechanized working face.It has a practical background elsewhere with more extensive applications.
基金Supported by the National Natural Science Foundation of Chinasupported by the National Basic Research Programof China (973 Program,2009CB824800)+2 种基金the China Postdoctoral Science Foundation funded project(No. 20110490590)the National Natural Science Foundation of China (Grant No. 111030262)the Foundation for the Authors of National Excellent Doctoral Dissertations of China
文摘Observations imply that long ＂y-ray bursts （GRBs） originate from the explo- sions of massive stars, therefore they may occur in the molecular clouds where their progenitors were born. We show that the prompt optical-UV emission from GRBs may be delayed due to dust extinction, which can explain the observed optical delayed on- set and fast rise in GRB 080319B well. The density and the size of the molecular cloud around GRB 080319B are roughly constrained to be ~ 103 cm-z and ~ 8 pc, respectively. We also investigate other GRBs with prompt optical-UV data, and find similar values of the densities and sizes of the local molecular clouds. Future obser- vations of prompt optical-UV emission from GRBs on a timescale of subseconds, e.g. by UFFO-Pathfinder and SVOM-GWAC, will provide more evidence and probes of the local environments of GRBs.
