To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmentalγ radiation dose rate from key radionuclides,particularly for large radioactive surface sources.T...To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmentalγ radiation dose rate from key radionuclides,particularly for large radioactive surface sources.The methods currently used for measuring dose rates are inadequate for obtaining the dose rates of key radionuclides and have large angular response errors when monitoring surface sources.To address this practical problem,this study proposes three methods for measuring the dose rate:the weighted peak total ratio,mean value regression,and numerical integration methods.These methods are based on energy-spectrum measurement data,and they were theoretically derived and numerically evaluated.Finally,a 1-m-long hexagonal radioactive surface source was integrated into a larger surface source.In situ measurement experiments were conducted on a large radioactive surface source using a dose-rate meter and a portable HPGespectrometer to analyze the errors of the three aforementioned methods and verify their validity.展开更多
By analyzing disposal status of unexpected environmental incidents by government,public and enterprise,and combining the characteristics of unexpected environmental incidents,specific measures of responding to unexpec...By analyzing disposal status of unexpected environmental incidents by government,public and enterprise,and combining the characteristics of unexpected environmental incidents,specific measures of responding to unexpected environmental incidents are proposed from the aspects of perfecting guarantee system of emergency nomocracy,enhancing information disclosure,encouraging public participation,enhancing the construction of emergency response capability,and enhancing post-event management,to improve the ability of defending environmental risk.展开更多
The outbreak of SARS in 2003 opened the way of public health emergency management in China.COVID-19 which suddenly outbroke in 2019 is still raging all over the world,and emergency management mechanism of China is bei...The outbreak of SARS in 2003 opened the way of public health emergency management in China.COVID-19 which suddenly outbroke in 2019 is still raging all over the world,and emergency management mechanism of China is being tested.Efforts to improve the emergency management mechanism can provide effective institutional guarantee for the overall victory of anti epidemic and the prevention and control of public health emergencies.展开更多
Aiming at the Four-Dimensional Variation source term inversion algorithm proposed earlier,the observation error regularization factor is introduced to improve the prediction accuracy of the diffusion model,and an impr...Aiming at the Four-Dimensional Variation source term inversion algorithm proposed earlier,the observation error regularization factor is introduced to improve the prediction accuracy of the diffusion model,and an improved Four-Dimensional Variation source term inversion algorithm with observation error regularization(OER-4DVAR STI model)is formed.Firstly,by constructing the inversion process and basic model of OER-4DVAR STI model,its basic principle and logical structure are studied.Secondly,the observation error regularization factor estimation method based on Bayesian optimization is proposed,and the error factor is separated and optimized by two parameters:error statistical time and deviation degree.Finally,the scientific,feasible and advanced nature of the OER-4DVAR STI model are verified by numerical simulation and tracer test data.The experimental results show that OER-4DVAR STI model can better reverse calculate the hazard source term information under the conditions of high atmospheric stability and flat underlying surface.Compared with the previous inversion algorithm,the source intensity estimation accuracy of OER-4DVAR STI model is improved by about 46.97%,and the source location estimation accuracy is improved by about 26.72%.展开更多
An ordered hollow M0S2 nanocages/RGO nanocomposite is constructed by a simple solvothermal-assisted assembly method combined with freeze-drying and annealing.In this novel nanostructure,hollow M0S2 nanocages are homog...An ordered hollow M0S2 nanocages/RGO nanocomposite is constructed by a simple solvothermal-assisted assembly method combined with freeze-drying and annealing.In this novel nanostructure,hollow M0S2 nanocages are homogeneously distributed on graphene sheets with a tight bond of C-O-Mo.The nanosized and hollow MoS2 nanocages can effectively accommodate the huge volume change during charge/discharge process and increase the number of electrochemical reaction active sites,accelerating the kinetics of lithiation/delithiation.The tight C-O-Mo bond between graphene and MoS2 further reinforces the structural stability,thus improve the electrical conductivity and substantially enhance the lithium storage performance of M0S2 anode material.As a result,this novel nanocomposite shows a long-cycle stability of 717.4 mAh·g^-1 after 800 cycles at a high current density of 3 A·g^-1,exhibiting great potential as an anode nanocomposite for advanced lithium-ion batteries.展开更多
Dynamic task allocation of unmanned aerial vehicle swarms for ground targets is an important part of unmanned aerial vehicle(UAV)swarms task planning and the key technology to improve autonomy.The realization of dynam...Dynamic task allocation of unmanned aerial vehicle swarms for ground targets is an important part of unmanned aerial vehicle(UAV)swarms task planning and the key technology to improve autonomy.The realization of dynamic task allocation in UAV swarms for ground targets is very difficult because of the large uncertainty of swarms,the target and environment state,and the high real-time allocation requirements.Hence,dynamic task allocation of UAV swarms oriented to ground targets has become a key and difficult problem in the field of mission planning.In this work,a dynamic task allocation method for UAV swarms oriented to ground targets is comprehensively and systematically summarized from two aspects:the establishment of an allocation model and the solution of the allocation model.First,the basic concept and trigger scenario are introduced.Second,the research status and the advantages and disadvantages of the two allocation models are analyzed.Third,the research status and the advantages and disadvantages of several common dynamic task allocation algorithms,such as the algorithm based on market mechanisms,intelligent optimization algorithm,and clustering algorithm,are evaluated.Finally,the specific problems of the current UAV swarm dynamic task allocation method for ground targets are highlighted,and future research directions are established.This work offers important reference significance for fully understanding the current situation of UAV swarm dynamic task allocation technology.展开更多
文摘To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmentalγ radiation dose rate from key radionuclides,particularly for large radioactive surface sources.The methods currently used for measuring dose rates are inadequate for obtaining the dose rates of key radionuclides and have large angular response errors when monitoring surface sources.To address this practical problem,this study proposes three methods for measuring the dose rate:the weighted peak total ratio,mean value regression,and numerical integration methods.These methods are based on energy-spectrum measurement data,and they were theoretically derived and numerically evaluated.Finally,a 1-m-long hexagonal radioactive surface source was integrated into a larger surface source.In situ measurement experiments were conducted on a large radioactive surface source using a dose-rate meter and a portable HPGespectrometer to analyze the errors of the three aforementioned methods and verify their validity.
文摘By analyzing disposal status of unexpected environmental incidents by government,public and enterprise,and combining the characteristics of unexpected environmental incidents,specific measures of responding to unexpected environmental incidents are proposed from the aspects of perfecting guarantee system of emergency nomocracy,enhancing information disclosure,encouraging public participation,enhancing the construction of emergency response capability,and enhancing post-event management,to improve the ability of defending environmental risk.
文摘The outbreak of SARS in 2003 opened the way of public health emergency management in China.COVID-19 which suddenly outbroke in 2019 is still raging all over the world,and emergency management mechanism of China is being tested.Efforts to improve the emergency management mechanism can provide effective institutional guarantee for the overall victory of anti epidemic and the prevention and control of public health emergencies.
基金Ministry of Science and Technology of the People’s Republic of China for its support and guidance(Grant No.2018YFC0214100)。
文摘Aiming at the Four-Dimensional Variation source term inversion algorithm proposed earlier,the observation error regularization factor is introduced to improve the prediction accuracy of the diffusion model,and an improved Four-Dimensional Variation source term inversion algorithm with observation error regularization(OER-4DVAR STI model)is formed.Firstly,by constructing the inversion process and basic model of OER-4DVAR STI model,its basic principle and logical structure are studied.Secondly,the observation error regularization factor estimation method based on Bayesian optimization is proposed,and the error factor is separated and optimized by two parameters:error statistical time and deviation degree.Finally,the scientific,feasible and advanced nature of the OER-4DVAR STI model are verified by numerical simulation and tracer test data.The experimental results show that OER-4DVAR STI model can better reverse calculate the hazard source term information under the conditions of high atmospheric stability and flat underlying surface.Compared with the previous inversion algorithm,the source intensity estimation accuracy of OER-4DVAR STI model is improved by about 46.97%,and the source location estimation accuracy is improved by about 26.72%.
基金This research was supported by the National Natural Science Foundation of China(No.51772150,21808103)Natural Science Foundation of Jiangsu Province(No.BK20171012)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).The authors are grateful to Dr.Lin Gao and the Reviewers for their helpful suggestions and comments.
文摘An ordered hollow M0S2 nanocages/RGO nanocomposite is constructed by a simple solvothermal-assisted assembly method combined with freeze-drying and annealing.In this novel nanostructure,hollow M0S2 nanocages are homogeneously distributed on graphene sheets with a tight bond of C-O-Mo.The nanosized and hollow MoS2 nanocages can effectively accommodate the huge volume change during charge/discharge process and increase the number of electrochemical reaction active sites,accelerating the kinetics of lithiation/delithiation.The tight C-O-Mo bond between graphene and MoS2 further reinforces the structural stability,thus improve the electrical conductivity and substantially enhance the lithium storage performance of M0S2 anode material.As a result,this novel nanocomposite shows a long-cycle stability of 717.4 mAh·g^-1 after 800 cycles at a high current density of 3 A·g^-1,exhibiting great potential as an anode nanocomposite for advanced lithium-ion batteries.
基金This work was partially supported by the Military Science Project of National Social Science Foundation(No.2019-SKJJ-C-092)the National Natural Science Foundation of China(No.61502534)+3 种基金the Natural Science Foundation of Shanxi Province(No.2020JQ-493)Military Equipment Research Project(No.WJ2020A020029)Military Theory Project of PAP(No.WJJY21JL0618)Research Foundation of Armed Police Force Engineering University(Nos.WJY202148 and JLY2020084).
文摘Dynamic task allocation of unmanned aerial vehicle swarms for ground targets is an important part of unmanned aerial vehicle(UAV)swarms task planning and the key technology to improve autonomy.The realization of dynamic task allocation in UAV swarms for ground targets is very difficult because of the large uncertainty of swarms,the target and environment state,and the high real-time allocation requirements.Hence,dynamic task allocation of UAV swarms oriented to ground targets has become a key and difficult problem in the field of mission planning.In this work,a dynamic task allocation method for UAV swarms oriented to ground targets is comprehensively and systematically summarized from two aspects:the establishment of an allocation model and the solution of the allocation model.First,the basic concept and trigger scenario are introduced.Second,the research status and the advantages and disadvantages of the two allocation models are analyzed.Third,the research status and the advantages and disadvantages of several common dynamic task allocation algorithms,such as the algorithm based on market mechanisms,intelligent optimization algorithm,and clustering algorithm,are evaluated.Finally,the specific problems of the current UAV swarm dynamic task allocation method for ground targets are highlighted,and future research directions are established.This work offers important reference significance for fully understanding the current situation of UAV swarm dynamic task allocation technology.
