With the development of high energy solid propellants,it is critical to evaluate the safety and power performance of solid propellants in the face of threats such as unmanned aerial vehicles(UAVs)when transporting and...With the development of high energy solid propellants,it is critical to evaluate the safety and power performance of solid propellants in the face of threats such as unmanned aerial vehicles(UAVs)when transporting and using them in contemporary warfare.An electric probe-type cylinder test measured the displacement-time behavior of NEPE high-energy solid propellant,and the parameters of the Jones-Wilkins-Lee(JWL)equation of state(EOS)were derived using particle swarm optimization(PSO)with the Gurney energy model.Further,the parameters of JWL-Miller EOS,determined through AUTODYN simulations,were validated by comparing airburst process simulations with experimental overpressure data.The study established a method for determining EOS parameters of high-energy propellants,achieving a high degree of accuracy.The derived parameters ensure precise modeling of propellant behavior,offering a reliable foundation for future applications in solid rocket motor performance optimization and safety assessment.展开更多
The degradation phenomena due to the energy pulse in the high-energy ZnO varistors used for deexitation and overvoltage protection of hydroelectric generator are investigated. The energy pulse, obtained by releasing t...The degradation phenomena due to the energy pulse in the high-energy ZnO varistors used for deexitation and overvoltage protection of hydroelectric generator are investigated. The energy pulse, obtained by releasing the energy stored in an inductor, can be equivalent to the combination of the DC field components and the energy component. The variations of the characterized voltages, nonlinear coefficients and pre-breakdown V-A characteristics, increase with the number of the applied energy pulse. The asymmetrical variations of the electric properties of the high-energy ZnO varistors after the energy pulse arise from the deformation of the double Schottky barriers due to the ion migration occuring in the depletion layer and in the grain boundary.展开更多
Space environment exploration is a hot topic globally.The scope of space exploration ranges from near-Earth space to the moon,other planets in the solar system,and even the heliosphere and interplanetary space.It is u...Space environment exploration is a hot topic globally.The scope of space exploration ranges from near-Earth space to the moon,other planets in the solar system,and even the heliosphere and interplanetary space.It is used for various crucial applications,including aerospace technology development,space weather research,understanding the origin and evolution of the universe,searching for extraterrestrial life,and finding human livable places.Although China’s space environment exploration started late,its progress has been rapid.China is gradually narrowing the gap with advanced countries and may eventually lead the world in space research.This article briefly reviews the development history of China’s space environmental detectors.展开更多
High-energy electron precipitation in the high latitude regions enhances the ionization of the atmosphere,and subsequently increases the atmospheric conductivities and the vertical electric field of the atmosphere nea...High-energy electron precipitation in the high latitude regions enhances the ionization of the atmosphere,and subsequently increases the atmospheric conductivities and the vertical electric field of the atmosphere near the ground as well.The High-Energy Electron Flux(HEEF) data measured by the Fengyun-3 meteorological satellite are analyzed together with the data of nearsurface atmospheric vertical electric field measured at the Russian Vostok Station.Three HEEF enhancements are identified and it is shown that when the HEEF increases to a certain level,the local atmospheric vertical electric field near the ground can increase substantially than usual.The response time of the electric field to HEEF enhancement is about 3.7 to 4 days.展开更多
Time-domain astrophysics will enter a golden era towards the end of this decade with the advent of major facilities across the electromagnetic spectrum and in the multi-messenger realms of gravitational wave and neutr...Time-domain astrophysics will enter a golden era towards the end of this decade with the advent of major facilities across the electromagnetic spectrum and in the multi-messenger realms of gravitational wave and neutrino.In the soft X-ray regime,the novel micro-pore lobster-eye optics provides a promising technology to realise,for the first time,focusing X-ray optics for wide-angle monitors to achieve a good combination of sensitivity and wide field of view.In this context Einstein Probe,a soft X-ray all-sky monitor mission,was proposed and selected as a candidate mission of priority in the space science programme of the Chinese Academy of Sciences.This paper reviews the most important science developments and key questions in this field towards 2020 and beyond,and how to achieve them technologically.It also introduces the Einstein Probe mission,including its key science goals and mission definition,as well as some of the key technological issues.展开更多
The preparation process of amorphous nanometer boron powders through combustion synthesis was investigated, and the effects of the reactant ratio, the heating agent and the milling rate on the activity and particle si...The preparation process of amorphous nanometer boron powders through combustion synthesis was investigated, and the effects of the reactant ratio, the heating agent and the milling rate on the activity and particle size of amorphous boron powders were studied. The results show that the boron powders exist in the form of an amorphous phase which has the crystallinity lower than 30.4%, and the panicle size of boron powder decreases with an increase of the high-energy ball milling rate. The purity of amorphous boron powder is 94.8% and panicle sizes are much smaller than 100 nm when the mass ratio of B2O3/Mg/KClO3 is 100：105：17 and the ball milling time is 20 min with the milling rate of 300 r/min. At the same time, the amorphous boron nano-fibers appear in the boron powders.展开更多
A new process of WC-Co cemented carbide was developed by using nano-grained W（Co, C） composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion（XRD）, differential thermal analysis ...A new process of WC-Co cemented carbide was developed by using nano-grained W（Co, C） composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion（XRD）, differential thermal analysis （DTA）, thermo-gravimetrie （TG） analysis and coercive forces of the sintered samples were adopted to analyze the phase transformation and constitution, and the microstructures of sintered samples were characterized by scanning electron microscopy（SEM）. The results show that the as-milled powders are transformed into transitional phases W2C and η （Co3W3C or Co6W6C） during sintering, and finally transformed into WC and Co phases completely at 1 250℃ for 30 min, and a large number of fibrous WC grains with about 1.2μm in length and 100 nm in radial dimension are formed in the sintered body at 1 300 ℃.展开更多
In this study,based on two attractive energetic compounds pentazole(PZ) and tetraazacubane(TAC),a new family of high energy and high nitrogen compounds pentazolyltetraazacubanes were designed.Then,a different number o...In this study,based on two attractive energetic compounds pentazole(PZ) and tetraazacubane(TAC),a new family of high energy and high nitrogen compounds pentazolyltetraazacubanes were designed.Then,a different number of NH2 or NO2 groups were introduced into the system to further adjust the property.The structures,properties,and the structure-property relationship of designed molecules were investigated theoretically.The results showed that all nine designed compounds have extremely high heat of formation(HOF,1226-2734 kJ/mol),good density(1,73-1.88 g/cm3),high detonation velocity(8.30-9.35 km/s),high detonation pressure(29.8-39.7 GPa) and acceptable sensitivity(△V:41-87 A3).These properties could be effectively positive adjusted by replacing one or two PZ rings by NH2 or/and NO2 groups,especially for the energy and sensitivity performance,which were increased and decreased obviously,respectively.As a result,two designed pentazolyltetraazacubanes were predicted to have higher energy and lower sensitivity than the famous high energy compound in use 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane,while two others have better co mbination property than 1,3,5-Trinitro-1,3,5-triazacyclohexane.In all,four new pentazolyltetraazacubanes with good combination performance were successfully designed by combining PZ with TAC,and the further property adjustment strategy of introducing a suitable amount of NH2/NO2 groups into the system.This work may help develop new cage energetic compounds.展开更多
基金supported by"the Fundamental Research Funds for the Central Universities",No.30924010503.
文摘With the development of high energy solid propellants,it is critical to evaluate the safety and power performance of solid propellants in the face of threats such as unmanned aerial vehicles(UAVs)when transporting and using them in contemporary warfare.An electric probe-type cylinder test measured the displacement-time behavior of NEPE high-energy solid propellant,and the parameters of the Jones-Wilkins-Lee(JWL)equation of state(EOS)were derived using particle swarm optimization(PSO)with the Gurney energy model.Further,the parameters of JWL-Miller EOS,determined through AUTODYN simulations,were validated by comparing airburst process simulations with experimental overpressure data.The study established a method for determining EOS parameters of high-energy propellants,achieving a high degree of accuracy.The derived parameters ensure precise modeling of propellant behavior,offering a reliable foundation for future applications in solid rocket motor performance optimization and safety assessment.
文摘The degradation phenomena due to the energy pulse in the high-energy ZnO varistors used for deexitation and overvoltage protection of hydroelectric generator are investigated. The energy pulse, obtained by releasing the energy stored in an inductor, can be equivalent to the combination of the DC field components and the energy component. The variations of the characterized voltages, nonlinear coefficients and pre-breakdown V-A characteristics, increase with the number of the applied energy pulse. The asymmetrical variations of the electric properties of the high-energy ZnO varistors after the energy pulse arise from the deformation of the double Schottky barriers due to the ion migration occuring in the depletion layer and in the grain boundary.
文摘Space environment exploration is a hot topic globally.The scope of space exploration ranges from near-Earth space to the moon,other planets in the solar system,and even the heliosphere and interplanetary space.It is used for various crucial applications,including aerospace technology development,space weather research,understanding the origin and evolution of the universe,searching for extraterrestrial life,and finding human livable places.Although China’s space environment exploration started late,its progress has been rapid.China is gradually narrowing the gap with advanced countries and may eventually lead the world in space research.This article briefly reviews the development history of China’s space environmental detectors.
基金Supported by the National Basic Research Program of China(2011CB811404)the Natural Science Foundation of China(40774081)+1 种基金the Specialized Research Fund for State Key LaboratoriesCAS-NSSC-135 project
文摘High-energy electron precipitation in the high latitude regions enhances the ionization of the atmosphere,and subsequently increases the atmospheric conductivities and the vertical electric field of the atmosphere near the ground as well.The High-Energy Electron Flux(HEEF) data measured by the Fengyun-3 meteorological satellite are analyzed together with the data of nearsurface atmospheric vertical electric field measured at the Russian Vostok Station.Three HEEF enhancements are identified and it is shown that when the HEEF increases to a certain level,the local atmospheric vertical electric field near the ground can increase substantially than usual.The response time of the electric field to HEEF enhancement is about 3.7 to 4 days.
基金Supported by the Strategic Priority Research Programme on Space Science of the Chinese Academy of Sciences(XDA04061100)
文摘Time-domain astrophysics will enter a golden era towards the end of this decade with the advent of major facilities across the electromagnetic spectrum and in the multi-messenger realms of gravitational wave and neutrino.In the soft X-ray regime,the novel micro-pore lobster-eye optics provides a promising technology to realise,for the first time,focusing X-ray optics for wide-angle monitors to achieve a good combination of sensitivity and wide field of view.In this context Einstein Probe,a soft X-ray all-sky monitor mission,was proposed and selected as a candidate mission of priority in the space science programme of the Chinese Academy of Sciences.This paper reviews the most important science developments and key questions in this field towards 2020 and beyond,and how to achieve them technologically.It also introduces the Einstein Probe mission,including its key science goals and mission definition,as well as some of the key technological issues.
基金Project(51002025) supported by the National Natural Science Foundation of China
文摘The preparation process of amorphous nanometer boron powders through combustion synthesis was investigated, and the effects of the reactant ratio, the heating agent and the milling rate on the activity and particle size of amorphous boron powders were studied. The results show that the boron powders exist in the form of an amorphous phase which has the crystallinity lower than 30.4%, and the panicle size of boron powder decreases with an increase of the high-energy ball milling rate. The purity of amorphous boron powder is 94.8% and panicle sizes are much smaller than 100 nm when the mass ratio of B2O3/Mg/KClO3 is 100：105：17 and the ball milling time is 20 min with the milling rate of 300 r/min. At the same time, the amorphous boron nano-fibers appear in the boron powders.
基金Project (50474049) supported by the National Natural Science Foundation of China
文摘A new process of WC-Co cemented carbide was developed by using nano-grained W（Co, C） composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion（XRD）, differential thermal analysis （DTA）, thermo-gravimetrie （TG） analysis and coercive forces of the sintered samples were adopted to analyze the phase transformation and constitution, and the microstructures of sintered samples were characterized by scanning electron microscopy（SEM）. The results show that the as-milled powders are transformed into transitional phases W2C and η （Co3W3C or Co6W6C） during sintering, and finally transformed into WC and Co phases completely at 1 250℃ for 30 min, and a large number of fibrous WC grains with about 1.2μm in length and 100 nm in radial dimension are formed in the sintered body at 1 300 ℃.
基金supported by the Natural Science Foundation of Nanjing Institute of Technology (CKJA201603)the Natural Science Foundation of Jiangsu Province(BK20170761,BK20160774)+3 种基金the Jiangsu Key Laboratory Opening Project of Advanced Structural Materials and Application Technology (ASMA201707)Science Innovation Project for Undergraduates of Jiangsu Province (201811276023Z)Outstanding Scientific and Technological Innovation Team in Colleges and Universities of Jiangsu ProvinceJiangsu Overseas Visiting Scholar Program for University Prominent Young & Middle-aged Teachers and Presidents
文摘In this study,based on two attractive energetic compounds pentazole(PZ) and tetraazacubane(TAC),a new family of high energy and high nitrogen compounds pentazolyltetraazacubanes were designed.Then,a different number of NH2 or NO2 groups were introduced into the system to further adjust the property.The structures,properties,and the structure-property relationship of designed molecules were investigated theoretically.The results showed that all nine designed compounds have extremely high heat of formation(HOF,1226-2734 kJ/mol),good density(1,73-1.88 g/cm3),high detonation velocity(8.30-9.35 km/s),high detonation pressure(29.8-39.7 GPa) and acceptable sensitivity(△V:41-87 A3).These properties could be effectively positive adjusted by replacing one or two PZ rings by NH2 or/and NO2 groups,especially for the energy and sensitivity performance,which were increased and decreased obviously,respectively.As a result,two designed pentazolyltetraazacubanes were predicted to have higher energy and lower sensitivity than the famous high energy compound in use 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane,while two others have better co mbination property than 1,3,5-Trinitro-1,3,5-triazacyclohexane.In all,four new pentazolyltetraazacubanes with good combination performance were successfully designed by combining PZ with TAC,and the further property adjustment strategy of introducing a suitable amount of NH2/NO2 groups into the system.This work may help develop new cage energetic compounds.
