The Centre for China and Globalisation(CCG)hosted a side event on February 17 titled"China,Europe,and the United States:Climate Cooperation in an Era of Great Power Politics"at the Munich Security Conference...The Centre for China and Globalisation(CCG)hosted a side event on February 17 titled"China,Europe,and the United States:Climate Cooperation in an Era of Great Power Politics"at the Munich Security Conference(MSC)2024,which was convened from February 16 to 18,2024 in Munich,Germany.展开更多
With a warming climate,temperature extremes have been a main global issue in recent decades due to their potential influence on the sustainable development of human life and natural ecosystems.In this study,12 indicat...With a warming climate,temperature extremes have been a main global issue in recent decades due to their potential influence on the sustainable development of human life and natural ecosystems.In this study,12 indicators of extreme temperature events are used to evaluate the spatiotemporal distribution,periodic structure and teleconnections with large-scale atmospheric circulation in Xinjiang,Northwest China by combining wavelet coherence(WTC) analysis based on continuous wavelet transform(CWT) analysis with the sequential Mann-Kendall test.We find that over the past six decades,the climate in Xinjiang has become warmer and has suffered from increases in the frequency of warm extremes and decreases in the frequency of cold extremes.Warm extremes have mainly occurred in the southern Tianshan Mountains surrounding the Tarim Basin and western part of the Taklamakan Desert,and cold extremes have primarily occurred in the southwestern Altai Mountains and northern foot of the Tianshan Mountains.Extreme temperature events,including warm extremes,cold extremes,and other temperature indices,have significant interannual variability,with the main oscillation periods at smaller(2–4-year band),intermediate(4–7-year band),and greater time scales in recent decades.Furthermore,cold-extreme indices,including frost days,cool days,and cool nights all show a clear changepoint during 1990–1997 at the 95% confidence level,and both ice days and cold spell duration indicator have a potential changepoint during 1981–1986.However,the changing points for warmextreme indices are detected during 1992–1998.The temperature variables are significantly correlated with the EI Ni?o-Southern Oscillation(ENSO) and Arctic Oscillation(AO),but less well correlated with the Pacific Decadal Oscillation(PDO).The phase difference in the WTC spectra is not uniform between temperature extremes and climatic oscillations.Our findings will have important implications for local governments in taking effective measures to mitigate the potential effects of regional climate warming due to human activities in Xinjiang.展开更多
Aiming at the industry cyber-physical system(ICPS)where Denial-of-Service(DoS)attacks and actuator failure coexist,the integrated security control problem of ICPS under multi-objective constraints was studied.First,fr...Aiming at the industry cyber-physical system(ICPS)where Denial-of-Service(DoS)attacks and actuator failure coexist,the integrated security control problem of ICPS under multi-objective constraints was studied.First,from the perspective of the defender,according to the differential impact of the system under DoS attacks of different energies,the DoS attacks energy grading detection standard was formulated,and the ICPS comprehensive security control framework was constructed.Secondly,a security transmission strategy based on event triggering was designed.Under the DoS attack energy classification detection mechanism,for large-energy attacks,the method based on time series analysis was considered to predict and compensate for lost data.Therefore,on the basis of passive and elastic response to small energy attacks,the active defense capability against DoS attacks was increased.Then by introducing the conecomplement linearization algorithm,the calculation methods of the state and fault estimation observer and the integrated safety controller were deduced,the goal of DoS attack active and passive hybrid intrusion tolerance and actuator failure active fault tolerance were realized.Finally,a simulation example of a four-capacity water tank system was given to verify the validity of the obtained conclusions.展开更多
The increasing frequency of compound extreme events under ongoing climate change threatens global food security.Compared to individual extreme events,the simultaneous occurrence of multiple extreme events can exacerba...The increasing frequency of compound extreme events under ongoing climate change threatens global food security.Compared to individual extreme events,the simultaneous occurrence of multiple extreme events can exacerbate crop yield reductions,yet comprehensive assessments of these compound effects remain limited.To bridge this gap,we applied a linear mixed-effects model to quantify the impacts of individual extreme events(cold days(CD)and killing degree days(KDD))and triple compound extreme events(heatwave and low precipitation(HWLP)and hot-dry-windy(HDW))on the global yields of winter wheat,soybeans,and maize from 1982 to 2016.Our analysis indicated that regions severely impacted by extreme events(exceeding the 95%threshold)experienced total crop yield losses of more than 9.16,24.89,26.69,and 7.12%due to CD,KDD,HWLP,and HDW,respectively.The adverse effects of compound events were particularly pronounced during critical growth stages.HWLP results in yield losses of 9.4%for winter wheat and 6.8%for maize per 10 hours of exposure during the heading to harvesting stages,while soybean yields declined by 8.8%per 10 hours during the planting to three-true-leaf stage.Similarly,KDD caused a 7.4%yield reduction in winter wheat per 10°C day during the heading to harvesting stages,a 9.5%reduction in maize per 10°C day during the planting to jointing stages,and a 3.8%reduction in soybean per 10°C day during the planting to three-true-leaf stages.These findings underscore the substantial contribution of compound extreme events,which are often overlooked in existing risk assessments,in determining the global yields of major staple crops.展开更多
This study investigates the major patterns of large-scale tilted ridges(LSTRS)over the Eurasian continent and their connections with large-scale surface air temperature during boreal winter.A total number of 134 LSTR ...This study investigates the major patterns of large-scale tilted ridges(LSTRS)over the Eurasian continent and their connections with large-scale surface air temperature during boreal winter.A total number of 134 LSTR events with zonal extent exceeding 90°of longitude on the peak day are identified.Using self-organizing map(SOM),the LSTRs are classified into five clusters that are characterized by different spatial distributions and orientations.The leading two clusters are closely associated with extensive and persistent cold events over different places.Considering the first cluster,LSTRs extend from the Ural Mountains to Northeast Asia and are favorable for the amplification and southeastward extension of the Siberian high.Therefore,this cluster is closely associated with the occurrence of extensive and persistent cold events in china.In comparison with the first cluster,the LSTRs of second group are situated to the west,with starting points from the Kola Peninsula,and cause extensive and persistent cold events over Eastern Europe,central Asia,and central Siberia.The results suggest that the vertical coupling between LSTRs and the corresponding anomalous sea level pressure is crucial for the persistent cold temperature events associated with the leading two SOM clusters.展开更多
With the load growth and the power grid expansion,the problem of short-circuit current(SCC)exceeding the secure limit in large-scale power grids has become more serious,which poses great challenge to the optimal secur...With the load growth and the power grid expansion,the problem of short-circuit current(SCC)exceeding the secure limit in large-scale power grids has become more serious,which poses great challenge to the optimal secure operation.Aiming at the SCC limitations,we use multiple back-toback voltage source converter based(B2B VSC)systems to separate a large-scale AC power grid into two asynchronous power grids.A multi-objective robust optimal secure operation model of large-scale power grid with multiple B2B VSC systems considering the SCC limitation is established based on the AC power flow equations.The decision variables include the on/off states of synchronous generators,power output,terminal voltage,transmission switching,bus sectionalization,and modulation ratios of B2B VSC systems.The influence of inner current sources of renewable energy generators on the system SCC is also considered.To improve the computational efficiency,a mixedinteger convex programming(MICP)framework based on convex relaxation methods including the inscribed N-sided approximation for the nonlinear SCC limitation constraints is proposed.Moreover,combined with the column-and-constraint generation(C&CG)algorithm,a method to directly solve the compromise optimal solution(COS)of the multi-objective robust optimal secure operation model is proposed.Finally,the effectiveness and computational efficiency of the proposed solution method is demonstrated by an actual 4407-bus provincial power grid and the modified IEEE 39-bus power grid,which can reduce the consumed CPU time of solving the COS by more than 90%and obtain a better COS.展开更多
This article describes the design and implementation of Residents Life Event Management System (hereinafter called as RLEMS) with high level reliability and security by blockchain technology. The data access environme...This article describes the design and implementation of Residents Life Event Management System (hereinafter called as RLEMS) with high level reliability and security by blockchain technology. The data access environment provided by blockchain is highly secure and trustworthy. In Blockchain system, some data fragments are grouped into one piece called as <i>blocks</i>, and all blocks are connected to create a chain of blocks in database. When blocks are connected, hash value is used to connect blocks properly. Blockchain technology enables highly secure and reliable data management system under relatively poor ICT environment. For example, developing countries such as African countries do not have sufficient ICT environment. Therefore adopting blockchain technology is suitable for such countries. Based on this consideration, we have started to build RLEMS on the blockchain system. In previous work, we used the MultiChain as a blockchain platform. However, as MultiChain platform is mainly for private blockchain system, it is not suitable for government-level data management system. Therefore, we tried to use another blockchain framework. We selected Hyperledger Fabric which was developed by Linux Foundation. It enables to implement all styles of blockchain system. This article describes the design and implementation of RLEMS by using Hyperledger Fabric. Furthermore, to provide the best user experience, we also built the web application interface with Java web application framework named PrimeFace. The implementation of a prototype revealed that the Hyperledger Fabric blockchain technology is more suitable than MultiChain.展开更多
Security in Ad Hoc network is an important issue under the opening circumstance of application service. Some protocols and models of security auditing have been proposed to ensure rationality of contracting strategy a...Security in Ad Hoc network is an important issue under the opening circumstance of application service. Some protocols and models of security auditing have been proposed to ensure rationality of contracting strategy and operating regulation and used to identify abnormal operation. Model of security auditing based on access control of devices will be advanced to register sign of devices and property of event of access control and to audit those actions. In the end, the model is analyzed and simulated.展开更多
The paper conducts analysis on the causes of dangerous goods road transportation accidents by applying analytic technique of security system science - Event Tree Analysis （ETA）. By computing minimum cut and minimal ...The paper conducts analysis on the causes of dangerous goods road transportation accidents by applying analytic technique of security system science - Event Tree Analysis （ETA）. By computing minimum cut and minimal path set of event tree and the important level of elementary event, the paper elicits the results that the factors of causing road transportation accident are multiple and its hazard is great while the paper also elicits the sorting of structural important level of elementary event. The paper offers the security countermeasures for dangerous goods road transportation which plays a vital role in safeguarding dangerous goods road transportation security.展开更多
With the increasing penetration of renewable energy in power system,renewable energy power ramp events(REPREs),dominated by wind power and photovoltaic power,pose significant threats to the secure and stable operation...With the increasing penetration of renewable energy in power system,renewable energy power ramp events(REPREs),dominated by wind power and photovoltaic power,pose significant threats to the secure and stable operation of power systems.This paper presents an early warning method for REPREs based on long short-term memory(LSTM)network and fuzzy logic.First,the warning levels of REPREs are defined by assessing the control costs of various power control measures.Then,the next 4-h power support capability of external grid is estimated by a tie line power predictionmodel,which is constructed based on the LSTMnetwork.Finally,considering the risk attitudes of dispatchers,fuzzy rules are employed to address the boundary value attribution of the early warning interval,improving the rationality of power ramp event early warning.Simulation results demonstrate that the proposed method can generate reasonable early warning levels for REPREs,guiding decision-making for control strategy.展开更多
Energy security planning is fundamental to safeguarding the traffic operation in large-scale events.To guarantee the promo-tion of green,zero-carbon,and environmental-friendly hydrogen fuel cell vehicles(HFCVs)in larg...Energy security planning is fundamental to safeguarding the traffic operation in large-scale events.To guarantee the promo-tion of green,zero-carbon,and environmental-friendly hydrogen fuel cell vehicles(HFCVs)in large-scale events,a five-stage planning method is proposed considering the demand and supply potential of hydrogen energy.Specifically,to meet the requirements of the large-scale events’demand,a new calculation approach is proposed to calculate the hydrogen amount and the distribution of hydrogen stations.In addition,energy supply is guaranteed from four aspects,namely hydrogen produc-tion,hydrogen storage,hydrogen delivery,and hydrogen refueling.The emergency plan is established based on the overall support plan,which can realize multi-dimensional energy security.Furthermore,the planning method is demonstrative as it powers the Beijing 2022 Winter Olympics as the first“green”Olympic,providing both theoretical and practical evidence for the energy security planning of large-scale events.This study provides suggestions about ensuring the energy demand after the race,broadening the application scenarios,and accelerating the application of HFCVs.展开更多
文摘The Centre for China and Globalisation(CCG)hosted a side event on February 17 titled"China,Europe,and the United States:Climate Cooperation in an Era of Great Power Politics"at the Munich Security Conference(MSC)2024,which was convened from February 16 to 18,2024 in Munich,Germany.
基金supported by the National Natural Science Foundation of China (No.41672246)the Fundamental Research Funds for the Central Universities,China University of Geosciences (Wuhan)(No.1910491T05)。
文摘With a warming climate,temperature extremes have been a main global issue in recent decades due to their potential influence on the sustainable development of human life and natural ecosystems.In this study,12 indicators of extreme temperature events are used to evaluate the spatiotemporal distribution,periodic structure and teleconnections with large-scale atmospheric circulation in Xinjiang,Northwest China by combining wavelet coherence(WTC) analysis based on continuous wavelet transform(CWT) analysis with the sequential Mann-Kendall test.We find that over the past six decades,the climate in Xinjiang has become warmer and has suffered from increases in the frequency of warm extremes and decreases in the frequency of cold extremes.Warm extremes have mainly occurred in the southern Tianshan Mountains surrounding the Tarim Basin and western part of the Taklamakan Desert,and cold extremes have primarily occurred in the southwestern Altai Mountains and northern foot of the Tianshan Mountains.Extreme temperature events,including warm extremes,cold extremes,and other temperature indices,have significant interannual variability,with the main oscillation periods at smaller(2–4-year band),intermediate(4–7-year band),and greater time scales in recent decades.Furthermore,cold-extreme indices,including frost days,cool days,and cool nights all show a clear changepoint during 1990–1997 at the 95% confidence level,and both ice days and cold spell duration indicator have a potential changepoint during 1981–1986.However,the changing points for warmextreme indices are detected during 1992–1998.The temperature variables are significantly correlated with the EI Ni?o-Southern Oscillation(ENSO) and Arctic Oscillation(AO),but less well correlated with the Pacific Decadal Oscillation(PDO).The phase difference in the WTC spectra is not uniform between temperature extremes and climatic oscillations.Our findings will have important implications for local governments in taking effective measures to mitigate the potential effects of regional climate warming due to human activities in Xinjiang.
基金supported by Gansu Higher Education Innovation Fund Project(No.2023B-439)。
文摘Aiming at the industry cyber-physical system(ICPS)where Denial-of-Service(DoS)attacks and actuator failure coexist,the integrated security control problem of ICPS under multi-objective constraints was studied.First,from the perspective of the defender,according to the differential impact of the system under DoS attacks of different energies,the DoS attacks energy grading detection standard was formulated,and the ICPS comprehensive security control framework was constructed.Secondly,a security transmission strategy based on event triggering was designed.Under the DoS attack energy classification detection mechanism,for large-energy attacks,the method based on time series analysis was considered to predict and compensate for lost data.Therefore,on the basis of passive and elastic response to small energy attacks,the active defense capability against DoS attacks was increased.Then by introducing the conecomplement linearization algorithm,the calculation methods of the state and fault estimation observer and the integrated safety controller were deduced,the goal of DoS attack active and passive hybrid intrusion tolerance and actuator failure active fault tolerance were realized.Finally,a simulation example of a four-capacity water tank system was given to verify the validity of the obtained conclusions.
基金supported by the National Natural Science Foundation of China(42371483,and 42401573)the Guangdong Basic and Applied Basic Research Foundation,China(2022B1515130001)+2 种基金the Natural Science Foundation of Guangdong Province,China(2024A1515012081 and 2025A1515010770)the Guangzhou Basic and Applied Basic Research Project,China(202201011666)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZB20240880).
文摘The increasing frequency of compound extreme events under ongoing climate change threatens global food security.Compared to individual extreme events,the simultaneous occurrence of multiple extreme events can exacerbate crop yield reductions,yet comprehensive assessments of these compound effects remain limited.To bridge this gap,we applied a linear mixed-effects model to quantify the impacts of individual extreme events(cold days(CD)and killing degree days(KDD))and triple compound extreme events(heatwave and low precipitation(HWLP)and hot-dry-windy(HDW))on the global yields of winter wheat,soybeans,and maize from 1982 to 2016.Our analysis indicated that regions severely impacted by extreme events(exceeding the 95%threshold)experienced total crop yield losses of more than 9.16,24.89,26.69,and 7.12%due to CD,KDD,HWLP,and HDW,respectively.The adverse effects of compound events were particularly pronounced during critical growth stages.HWLP results in yield losses of 9.4%for winter wheat and 6.8%for maize per 10 hours of exposure during the heading to harvesting stages,while soybean yields declined by 8.8%per 10 hours during the planting to three-true-leaf stage.Similarly,KDD caused a 7.4%yield reduction in winter wheat per 10°C day during the heading to harvesting stages,a 9.5%reduction in maize per 10°C day during the planting to jointing stages,and a 3.8%reduction in soybean per 10°C day during the planting to three-true-leaf stages.These findings underscore the substantial contribution of compound extreme events,which are often overlooked in existing risk assessments,in determining the global yields of major staple crops.
基金jointly supported by the National Natural Science Foundation of China [grant number 41375064 and41675086]the National Key Technology Research and Development Program of the Ministry of Science and Technology of China [grant number 2015BAC03B03]
文摘This study investigates the major patterns of large-scale tilted ridges(LSTRS)over the Eurasian continent and their connections with large-scale surface air temperature during boreal winter.A total number of 134 LSTR events with zonal extent exceeding 90°of longitude on the peak day are identified.Using self-organizing map(SOM),the LSTRs are classified into five clusters that are characterized by different spatial distributions and orientations.The leading two clusters are closely associated with extensive and persistent cold events over different places.Considering the first cluster,LSTRs extend from the Ural Mountains to Northeast Asia and are favorable for the amplification and southeastward extension of the Siberian high.Therefore,this cluster is closely associated with the occurrence of extensive and persistent cold events in china.In comparison with the first cluster,the LSTRs of second group are situated to the west,with starting points from the Kola Peninsula,and cause extensive and persistent cold events over Eastern Europe,central Asia,and central Siberia.The results suggest that the vertical coupling between LSTRs and the corresponding anomalous sea level pressure is crucial for the persistent cold temperature events associated with the leading two SOM clusters.
基金supported by the National Natural Science Foundation of China(No.51977080).
文摘With the load growth and the power grid expansion,the problem of short-circuit current(SCC)exceeding the secure limit in large-scale power grids has become more serious,which poses great challenge to the optimal secure operation.Aiming at the SCC limitations,we use multiple back-toback voltage source converter based(B2B VSC)systems to separate a large-scale AC power grid into two asynchronous power grids.A multi-objective robust optimal secure operation model of large-scale power grid with multiple B2B VSC systems considering the SCC limitation is established based on the AC power flow equations.The decision variables include the on/off states of synchronous generators,power output,terminal voltage,transmission switching,bus sectionalization,and modulation ratios of B2B VSC systems.The influence of inner current sources of renewable energy generators on the system SCC is also considered.To improve the computational efficiency,a mixedinteger convex programming(MICP)framework based on convex relaxation methods including the inscribed N-sided approximation for the nonlinear SCC limitation constraints is proposed.Moreover,combined with the column-and-constraint generation(C&CG)algorithm,a method to directly solve the compromise optimal solution(COS)of the multi-objective robust optimal secure operation model is proposed.Finally,the effectiveness and computational efficiency of the proposed solution method is demonstrated by an actual 4407-bus provincial power grid and the modified IEEE 39-bus power grid,which can reduce the consumed CPU time of solving the COS by more than 90%and obtain a better COS.
文摘This article describes the design and implementation of Residents Life Event Management System (hereinafter called as RLEMS) with high level reliability and security by blockchain technology. The data access environment provided by blockchain is highly secure and trustworthy. In Blockchain system, some data fragments are grouped into one piece called as <i>blocks</i>, and all blocks are connected to create a chain of blocks in database. When blocks are connected, hash value is used to connect blocks properly. Blockchain technology enables highly secure and reliable data management system under relatively poor ICT environment. For example, developing countries such as African countries do not have sufficient ICT environment. Therefore adopting blockchain technology is suitable for such countries. Based on this consideration, we have started to build RLEMS on the blockchain system. In previous work, we used the MultiChain as a blockchain platform. However, as MultiChain platform is mainly for private blockchain system, it is not suitable for government-level data management system. Therefore, we tried to use another blockchain framework. We selected Hyperledger Fabric which was developed by Linux Foundation. It enables to implement all styles of blockchain system. This article describes the design and implementation of RLEMS by using Hyperledger Fabric. Furthermore, to provide the best user experience, we also built the web application interface with Java web application framework named PrimeFace. The implementation of a prototype revealed that the Hyperledger Fabric blockchain technology is more suitable than MultiChain.
文摘Security in Ad Hoc network is an important issue under the opening circumstance of application service. Some protocols and models of security auditing have been proposed to ensure rationality of contracting strategy and operating regulation and used to identify abnormal operation. Model of security auditing based on access control of devices will be advanced to register sign of devices and property of event of access control and to audit those actions. In the end, the model is analyzed and simulated.
文摘The paper conducts analysis on the causes of dangerous goods road transportation accidents by applying analytic technique of security system science - Event Tree Analysis （ETA）. By computing minimum cut and minimal path set of event tree and the important level of elementary event, the paper elicits the results that the factors of causing road transportation accident are multiple and its hazard is great while the paper also elicits the sorting of structural important level of elementary event. The paper offers the security countermeasures for dangerous goods road transportation which plays a vital role in safeguarding dangerous goods road transportation security.
基金funded by State Grid Shandong Electric Power Company Technology Project(520626220110).
文摘With the increasing penetration of renewable energy in power system,renewable energy power ramp events(REPREs),dominated by wind power and photovoltaic power,pose significant threats to the secure and stable operation of power systems.This paper presents an early warning method for REPREs based on long short-term memory(LSTM)network and fuzzy logic.First,the warning levels of REPREs are defined by assessing the control costs of various power control measures.Then,the next 4-h power support capability of external grid is estimated by a tie line power predictionmodel,which is constructed based on the LSTMnetwork.Finally,considering the risk attitudes of dispatchers,fuzzy rules are employed to address the boundary value attribution of the early warning interval,improving the rationality of power ramp event early warning.Simulation results demonstrate that the proposed method can generate reasonable early warning levels for REPREs,guiding decision-making for control strategy.
基金The authors thank the support of colleagues from Beijing Transport Institute.
文摘Energy security planning is fundamental to safeguarding the traffic operation in large-scale events.To guarantee the promo-tion of green,zero-carbon,and environmental-friendly hydrogen fuel cell vehicles(HFCVs)in large-scale events,a five-stage planning method is proposed considering the demand and supply potential of hydrogen energy.Specifically,to meet the requirements of the large-scale events’demand,a new calculation approach is proposed to calculate the hydrogen amount and the distribution of hydrogen stations.In addition,energy supply is guaranteed from four aspects,namely hydrogen produc-tion,hydrogen storage,hydrogen delivery,and hydrogen refueling.The emergency plan is established based on the overall support plan,which can realize multi-dimensional energy security.Furthermore,the planning method is demonstrative as it powers the Beijing 2022 Winter Olympics as the first“green”Olympic,providing both theoretical and practical evidence for the energy security planning of large-scale events.This study provides suggestions about ensuring the energy demand after the race,broadening the application scenarios,and accelerating the application of HFCVs.
