Based on the dynamic analysis and research of pollution risk of groundwater sources, this paper creates the dynamic assessment method of pollution risk of groundwater source area under the theory of "source-pathw...Based on the dynamic analysis and research of pollution risk of groundwater sources, this paper creates the dynamic assessment method of pollution risk of groundwater source area under the theory of "source-pathway-receptor", and applies this method to one typical fissure karst groundwater source area in northern China. Following the 30-year petroleum pollutant migration simulation and pollution risk assessment of groundwater source area, this study finds that the very high risk zone is mainly located in Q Petrochemical Company and the surrounding area and the area adjacent to River Z. Within this period of thirty years, the pollution risk of groundwater source area has showed a dynamic trend that features an inverted "V" shape. The ratio of very high risk zone to the total area will be 18.1%, 17.47% and 16.62% during the tenth year, the twentieth year and the thirtieth year separately, and will reach the highest level of 19.45% during the fifteenth year. Meanwhile, the vertical migration distance of pollutant centre concentration changed from the surface soil at the outset to the deepest point of about 250 meters underground during the tenth year. The results of this risk assessment indicate the dynamic feature of pollution risk. The dilution, degradation and migration of petroleum pollutants in groundwater system contribute to an ultimate decline in pollution risk.展开更多
With the help of advanced information technology,real-time monitoring and control levels of cyber-physical distribution systems(CPDS)have been significantly improved.However due to the deep integration of cyber and ph...With the help of advanced information technology,real-time monitoring and control levels of cyber-physical distribution systems(CPDS)have been significantly improved.However due to the deep integration of cyber and physical systems,attackers could still threaten the stable operation of CPDS by launching cyber-attacks,such as denial-of-service(DoS)attacks.Thus,it is necessary to study the CPDS risk assessment and defense resource allocation methods under DoS attacks.This paper analyzes the impact of DoS attacks on the physical system based on the CPDS fault self-healing control.Then,considering attacker and defender strategies and attack damage,a CPDS risk assessment framework is established.Furthermore,risk assessment and defense resource allocation methods,based on the Stackelberg dynamic game model,are proposed under conditions in which the cyber and physical systems are launched simultaneously.Finally,a simulation based on an actual CPDS is performed,and the calculation results verify the effectiveness of the algorithm.展开更多
The paper presents a practical dynamic security region (PDSR) based dynamic security risk assessment and optimization model for power transmission system. The cost of comprehensive security control and the influence o...The paper presents a practical dynamic security region (PDSR) based dynamic security risk assessment and optimization model for power transmission system. The cost of comprehensive security control and the influence of uncertainties of power injections are considered in the model of dynamic security risk assessment. The transient stability constraints and uncertainties of power injections can be considered easily by PDSR in form of hyper-box. A method to define and classify contingency set is presented, and a risk control optimization model is given which takes total dynamic insecurity risk as the objective function for a dominant con-tingency set. An optimal solution of dynamic insecurity risk is obtained by opti-mizing preventive and emergency control cost and contingency set decomposition. The effectiveness of this model has been proved by test results on the New Eng-land 10-genarator 39-bus system.展开更多
The development of innovative, complex marine systems, such as autonomous ship concepts, has led to risk-based approaches indesign and operation that provide safety level quantification and continuous risk assessment....The development of innovative, complex marine systems, such as autonomous ship concepts, has led to risk-based approaches indesign and operation that provide safety level quantification and continuous risk assessment. The existing approaches to dynamicrisk assessmentmainly aim at updating accident probabilities for specific risk scenarios, based on knowledge of system operation andfailure, aswell as on past accident and failure information. However, for innovative marine systems that include complex interactions,our ability to identify anything that might go wrong is very limited, which may lead to unidentified risks, and failure data may not beavailable. This paper presents the foundations of a framework for dynamic risk assessment, which is equally applicable to mannedand autonomous ships and mainly relies on information about the safe operational envelope and real-time information regardingdeviations from safety. Inspiration is drawn from how the biological immune system identifies the risk of infection in a dynamicenvironment. The objective is to show the feasibility and benefits of our approach for quantifying the operational risk of marinesystems. This paper provides the conceptual basis for developing ship specific applications and describes a process for dynamic riskassessment that is methodologically based on artificial immune systems. To demonstrate the implementation of our framework, wedescribed, an illustrative example that involves a ship in a grounding scenario. The results show that the bio-inspired assessmentprocess and risk description can reflect the changes of the risk level of a marine system.展开更多
基金Foundation project:the Specific Research on Public Service of Environmental Protection in China(201009009)
文摘Based on the dynamic analysis and research of pollution risk of groundwater sources, this paper creates the dynamic assessment method of pollution risk of groundwater source area under the theory of "source-pathway-receptor", and applies this method to one typical fissure karst groundwater source area in northern China. Following the 30-year petroleum pollutant migration simulation and pollution risk assessment of groundwater source area, this study finds that the very high risk zone is mainly located in Q Petrochemical Company and the surrounding area and the area adjacent to River Z. Within this period of thirty years, the pollution risk of groundwater source area has showed a dynamic trend that features an inverted "V" shape. The ratio of very high risk zone to the total area will be 18.1%, 17.47% and 16.62% during the tenth year, the twentieth year and the thirtieth year separately, and will reach the highest level of 19.45% during the fifteenth year. Meanwhile, the vertical migration distance of pollutant centre concentration changed from the surface soil at the outset to the deepest point of about 250 meters underground during the tenth year. The results of this risk assessment indicate the dynamic feature of pollution risk. The dilution, degradation and migration of petroleum pollutants in groundwater system contribute to an ultimate decline in pollution risk.
基金supported in part by the National Key Research and Development Program of China(2017YFB0903000)in part by the National Natural Science Foundation of China(No.51677116).
文摘With the help of advanced information technology,real-time monitoring and control levels of cyber-physical distribution systems(CPDS)have been significantly improved.However due to the deep integration of cyber and physical systems,attackers could still threaten the stable operation of CPDS by launching cyber-attacks,such as denial-of-service(DoS)attacks.Thus,it is necessary to study the CPDS risk assessment and defense resource allocation methods under DoS attacks.This paper analyzes the impact of DoS attacks on the physical system based on the CPDS fault self-healing control.Then,considering attacker and defender strategies and attack damage,a CPDS risk assessment framework is established.Furthermore,risk assessment and defense resource allocation methods,based on the Stackelberg dynamic game model,are proposed under conditions in which the cyber and physical systems are launched simultaneously.Finally,a simulation based on an actual CPDS is performed,and the calculation results verify the effectiveness of the algorithm.
基金Supported by the key research of the National Natural Science Foundation of China (Grant No. 50595413) The National Basic Research Program of China (973 Program) (Grant No. 2004CB217904)
文摘The paper presents a practical dynamic security region (PDSR) based dynamic security risk assessment and optimization model for power transmission system. The cost of comprehensive security control and the influence of uncertainties of power injections are considered in the model of dynamic security risk assessment. The transient stability constraints and uncertainties of power injections can be considered easily by PDSR in form of hyper-box. A method to define and classify contingency set is presented, and a risk control optimization model is given which takes total dynamic insecurity risk as the objective function for a dominant con-tingency set. An optimal solution of dynamic insecurity risk is obtained by opti-mizing preventive and emergency control cost and contingency set decomposition. The effectiveness of this model has been proved by test results on the New Eng-land 10-genarator 39-bus system.
文摘The development of innovative, complex marine systems, such as autonomous ship concepts, has led to risk-based approaches indesign and operation that provide safety level quantification and continuous risk assessment. The existing approaches to dynamicrisk assessmentmainly aim at updating accident probabilities for specific risk scenarios, based on knowledge of system operation andfailure, aswell as on past accident and failure information. However, for innovative marine systems that include complex interactions,our ability to identify anything that might go wrong is very limited, which may lead to unidentified risks, and failure data may not beavailable. This paper presents the foundations of a framework for dynamic risk assessment, which is equally applicable to mannedand autonomous ships and mainly relies on information about the safe operational envelope and real-time information regardingdeviations from safety. Inspiration is drawn from how the biological immune system identifies the risk of infection in a dynamicenvironment. The objective is to show the feasibility and benefits of our approach for quantifying the operational risk of marinesystems. This paper provides the conceptual basis for developing ship specific applications and describes a process for dynamic riskassessment that is methodologically based on artificial immune systems. To demonstrate the implementation of our framework, wedescribed, an illustrative example that involves a ship in a grounding scenario. The results show that the bio-inspired assessmentprocess and risk description can reflect the changes of the risk level of a marine system.
