During geomagnetically active times such as geomagnetic storms,large amounts of energy can be released into the Earth’s magnetosphere and change the ring current intensity.Previous studies showed that significant enh...During geomagnetically active times such as geomagnetic storms,large amounts of energy can be released into the Earth’s magnetosphere and change the ring current intensity.Previous studies showed that significant enhancement of the ring current was related to geomagnetic storms,while few studies have examined substorm effects on ring current dynamics.In this study,we examine the ring current variation during non-storm time(SYM-H>−50 nT)substorms,especially during super-substorms(AE>1000 nT).We perform a statistical analysis of ring current plasma pressure and number flux of various ion species under different substorm conditions,based on Van Allen Probe observations.The plasma pressure and ion fluxes of the ring current increased dramatically during supersubstorms,while little change was observed for substorms with AE<1000 nT.The results shown in this study indicate that a non-storm time super-substorm may also have a significant contribution to the ring current.展开更多
The graphene is used to enhance the thermal conductivity, but it is difficult to obtain uniform dispersion and low dielectric property. We fabricate the polyimide composite with high thermal conductivity and low diele...The graphene is used to enhance the thermal conductivity, but it is difficult to obtain uniform dispersion and low dielectric property. We fabricate the polyimide composite with high thermal conductivity and low dielectric property. It changes the filler contents, and examines curing time and dispersion. The dispersion characteristics were quantified by absorbance measurement. The graphene 0.1 wt% and BN 0.5 wt% polyimide composites show a thermal conductivity of 6.6 W/m®K by LFA (Laser Flash Analysis) and a dielectric constant of 4.6@10 GHz by SPDR (Split Post Dielectric Resonators).展开更多
The heat dissipated pad is made of composite mixing silicon or epoxy resin with thermal conductive inorganic fillers. The heat-dissipation material improves performance as the amount of thermal conductivity filler inc...The heat dissipated pad is made of composite mixing silicon or epoxy resin with thermal conductive inorganic fillers. The heat-dissipation material improves performance as the amount of thermal conductivity filler increases. However, the optimum recipe should be determined by considering the price and pad formability. In this study, high performance thermal pad is made of silicon resin mixed with Al2O3 as a thermally conductive filler. Since Al2O3 is low cost, it can use much filler. Al2O3 has improved slip-ability with organic coating on it to increase the viscosity of the slurry. The same process and the same recipe, could maximize the amount of the filler. As a result, the thermal conductivity is lower by 10%. But the viscosity is reduced by 60%, too. So form-ability is getting priority.展开更多
基金supported by a research grant of China National Space Administration project D020303,NSFC Grant Numbers:41974191the National Key R&D Program of China 2020YFE0202100。
文摘During geomagnetically active times such as geomagnetic storms,large amounts of energy can be released into the Earth’s magnetosphere and change the ring current intensity.Previous studies showed that significant enhancement of the ring current was related to geomagnetic storms,while few studies have examined substorm effects on ring current dynamics.In this study,we examine the ring current variation during non-storm time(SYM-H>−50 nT)substorms,especially during super-substorms(AE>1000 nT).We perform a statistical analysis of ring current plasma pressure and number flux of various ion species under different substorm conditions,based on Van Allen Probe observations.The plasma pressure and ion fluxes of the ring current increased dramatically during supersubstorms,while little change was observed for substorms with AE<1000 nT.The results shown in this study indicate that a non-storm time super-substorm may also have a significant contribution to the ring current.
文摘The graphene is used to enhance the thermal conductivity, but it is difficult to obtain uniform dispersion and low dielectric property. We fabricate the polyimide composite with high thermal conductivity and low dielectric property. It changes the filler contents, and examines curing time and dispersion. The dispersion characteristics were quantified by absorbance measurement. The graphene 0.1 wt% and BN 0.5 wt% polyimide composites show a thermal conductivity of 6.6 W/m®K by LFA (Laser Flash Analysis) and a dielectric constant of 4.6@10 GHz by SPDR (Split Post Dielectric Resonators).
文摘The heat dissipated pad is made of composite mixing silicon or epoxy resin with thermal conductive inorganic fillers. The heat-dissipation material improves performance as the amount of thermal conductivity filler increases. However, the optimum recipe should be determined by considering the price and pad formability. In this study, high performance thermal pad is made of silicon resin mixed with Al2O3 as a thermally conductive filler. Since Al2O3 is low cost, it can use much filler. Al2O3 has improved slip-ability with organic coating on it to increase the viscosity of the slurry. The same process and the same recipe, could maximize the amount of the filler. As a result, the thermal conductivity is lower by 10%. But the viscosity is reduced by 60%, too. So form-ability is getting priority.
