针对现有基于角色的访问控制模型(role-based access control,RBAC)服务请求中缺乏关键权限管理办法及其算法的指数级复杂度,设计了一种高效的管理方法.该方法是在简化的系统模型(simplify system model,SSM)上通过建立基于权限的访问...针对现有基于角色的访问控制模型(role-based access control,RBAC)服务请求中缺乏关键权限管理办法及其算法的指数级复杂度,设计了一种高效的管理方法.该方法是在简化的系统模型(simplify system model,SSM)上通过建立基于权限的访问控制列表(privilege-based access control list,PBACL)来管理关键权限;通过自定义的角色关系结构体将系统角色横向和纵向划分.该方法针对不同的外部服务请求,通过自定义的角色加法(role plus,RP)可以简单快速地查找出最佳角色集,其复杂度仅为多项式级;能够解决关键权限被赋予多个用户从而导致的安全冲突问题;支持系统模型在"不稳定型"系统中的快速重构.该方法同样适用于多域环境下的访问控制,能够有效地避免多域环境下关键权限多分配的问题,能够快速检测出由于域间映射带来安全冲突问题例如:循环继承冲突和角色互斥约束冲突等.展开更多
A new safety assessment method for parallel routes is presented. From the aspects of safety guard system of air traffic control（ATC） and considering the flight conflict as causing event of air collision accidents, t...A new safety assessment method for parallel routes is presented. From the aspects of safety guard system of air traffic control（ATC） and considering the flight conflict as causing event of air collision accidents, this paper fosters a four-layer safety guard of controller command, short-term conflict alerts （STCAs）, pilot visual avoidance, and traffic alert collision avoidance system（TCAS）. Then, the problem of parallel routes collision risk is divided into two parts：the calculation of potential flight conflict and the analysis of failure probability of the four-layer safety guard. A calculation model for controller interference times is induced. By using cognitive reliability and error analysis method（CREAM）,the calculation problem to failure probability of controller sequencing flight conflicts is solved and a fault tree model of guard failure of STCA and TCAS is established. Finally, the Beijing-Shanghai parallel routes are taken as an example to be calculated and the collision risk of the parallel routes is obtained under the condition of radar control. Results show that the parallel routes can satisfy the safety demands.展开更多
Due to the fact that there is no protected signal phase for right turns at most signalized intersections, the conflict between pedestrians and right-turning vehicles is one of the most common conflict types for pedest...Due to the fact that there is no protected signal phase for right turns at most signalized intersections, the conflict between pedestrians and right-turning vehicles is one of the most common conflict types for pedestrians. A pedestrian safety analysis of the common right-turn mode at four-phase signalized intersections is presented. Relative risk is used as a measure of the effect of behaviors. The analysis mainly includes five pedestrian factors that affect the conflict process between pedestrians and right-turning vehicles. Pedestrians tend to have a higher risk of being involved in conflicts in the following six situations: crossing with others, running over the crossing, entering the intersection, being near the exit lane, crossing in the middle or at the end of a green light when the right-turn lane is shared, crossing at the beginning of a green light or red period when the right-turn lane is exclusive. It is easier for pedestrians to get priority when crossing the street in the following situations: running over a crossing, entering the intersection, being near the entrance lane, and not using the crosswalk. However, pedestrians are more inclined to yield to right-turning vehicles when pedestrians are crossing in the middle of the green light time. Some measures to alleviate the conflict are put forward according to the conclusion. Video observations also indicate that a clear pedestrian waiting area must be marked for both pedestrian safety and right-turning vehicle efficiency at major flat intersections, particularly when the arms cover the lateral dividing strips.展开更多
How to protect the database, the kernel resources of information warfare, is becoming more and more important since the rapid development of computer and communication technology. As an application-level firewall, dat...How to protect the database, the kernel resources of information warfare, is becoming more and more important since the rapid development of computer and communication technology. As an application-level firewall, database security proxy can successfully repulse attacks originated from outside the network, reduce to zerolevel damage from foreign DBMS products. We enhanced the capability of the COAST' s firewall reference model by adding a transmission unit modification function and an attribute value mapping function,describes the schematic and semantic layer reference model, and finally forms a reference model for DBMS security proxy which greatly helps in the design and implementation of database security proxies. This modeling process can clearly separate the system functionality into three layers, define the possible security functions for each layer, and estimate the computational cost for each layer.展开更多
Comparative analyses were conducted to compare the effects of the behavioral characteristics of the drivers of taxis and private cars on the capacity and safety of signalized intersections. Data were collected at sixt...Comparative analyses were conducted to compare the effects of the behavioral characteristics of the drivers of taxis and private cars on the capacity and safety of signalized intersections. Data were collected at sixteen signalized intersections in the Nanjing area in China. The risk-taking behaviors of the drivers of taxis and private cars were compared. The results suggest that 19.9% of taxi drivers have committed at least one of the identified risky behaviors, which is 2.37 times as high as that of the drivers of private cars(8.4%). The traffic conflicts technique was used to estimate the safety effects of taxis and private cars. The overall conflict rate for taxis is 21.4% higher than that for private cars, implying that taxis are more likely to be involved in conflicts. Almost all of the identified traffic conflicts can be attributed to certain levels of risk-taking behaviors committed by either taxi drivers or the drivers of private cars, and taxi drivers are more likely to be at fault in a conflict. Failure to yield to right-of-way and improper lane change is the leading causes of the conflicts in which taxis are at-fault. The research team further studied the effects of taxis on the queue discharge characteristics at signalized intersections. The results show that the presence of taxis significantly reduces both start-up lost time and saturation headways. The effects of taxis on saturation flow rates are dependent on the proportion of taxis in the discharge flow, and the saturation flow rates increase with the increase in the proportion of taxis. The adjustment factors for various proportions of taxis for different turning movements are then calculated to quantitatively evaluate the effects of taxis on the capacity of signalized intersections.展开更多
From June to July of 2017, the approval rates of the Abe administration fell sharply, in stark contrast to the long-term stability since 2012. The stability of Abe＇ s approval rates originated from the people＇ s neg...From June to July of 2017, the approval rates of the Abe administration fell sharply, in stark contrast to the long-term stability since 2012. The stability of Abe＇ s approval rates originated from the people＇ s negative support for him and their opposition to the Security Laws and other important events as well as the scandals under his administration. The opposition and negative support originated from the people＇s ＂acquired helplessness＂, ＂Abenomics＂, the sharp drop in the opporttmity costs of voting and other conditions. The sudden fall of Abe＇ s approval rates was not due to the change in the aforementioned conditions, rather because of the collapse of his image including personality owing to Abe＇ s perceived arrogance and his estrangement with the people. In the context of the temporary stabilization of approval rates, Abe dissolved the House of Representatives ahead of schedule and held a general election, taking full advantage of the internal strife between the opposition parties, to achieve his goal of ruling until the 2020 Tokyo Olympics. His victory in the recent election does not accurately demonstrate that Abe is completely immune to negative impact, thus he will to use the Korean Peninsula crisis and other issues to demonstrate his ability of safeguarding Japan＇s security, seek reconstruction of his image, and further enhance his approval rate to stabilize his administration.展开更多
West China provides important ecological services to the rest of the country, and has attracted great attention because of its serious ecological degradation and frequent natural disasters, and its strong connection w...West China provides important ecological services to the rest of the country, and has attracted great attention because of its serious ecological degradation and frequent natural disasters, and its strong connection with the industrial and economic development in East China. In order to strengthen ecological restoration and promote sustainable economic development in West China, the Chinese government adopted the Western Development Policy, which offered financial aid to and initiated a large number of projects in the region. Although many previous studies have emphasized the positive effects of ecological restoration in West China on ecological security and sustainable development of China, relatively less attention has been paid to analyzing multiple conflicts related to sustainable development in the region. This paper examines the main development goals and interests that have caused these conflicts. The authors suggest that integrated conflict management should be carried out for the sustainable development in West China.展开更多
The relation between the United States and the Democratic People＇s Republic of Korea （DPRK） is of substantial strategic prominence in the security landscape of Northeast Asia. The longstanding incompatibility betwe...The relation between the United States and the Democratic People＇s Republic of Korea （DPRK） is of substantial strategic prominence in the security landscape of Northeast Asia. The longstanding incompatibility between the two countries can be illuminated by drawing on three factors： the conflict of interest in the DPRK-ROK unification; the strategic interests of the nuclearization and the denuclearization-normalization dilemma; the Sino-U.S. dual power structure in Northeast Asia. In addressing these issues, this paper discusses the possibility of achieving diplomatic normalization between the U.S. and DPRK by examining in a comparative framework the feasibility of existing mechanisms. The paper concludes that unconventional mechanism is required to establish the initial momentum for a necessary political breakthrough, especially in light of the Trump phenomenon. Specifically, the author proposes a stepwise model to assist the diplomatic reconciliation and to further promote the restoration of peace, security and stability in Northeast Asia.展开更多
文摘针对现有基于角色的访问控制模型(role-based access control,RBAC)服务请求中缺乏关键权限管理办法及其算法的指数级复杂度,设计了一种高效的管理方法.该方法是在简化的系统模型(simplify system model,SSM)上通过建立基于权限的访问控制列表(privilege-based access control list,PBACL)来管理关键权限;通过自定义的角色关系结构体将系统角色横向和纵向划分.该方法针对不同的外部服务请求,通过自定义的角色加法(role plus,RP)可以简单快速地查找出最佳角色集,其复杂度仅为多项式级;能够解决关键权限被赋予多个用户从而导致的安全冲突问题;支持系统模型在"不稳定型"系统中的快速重构.该方法同样适用于多域环境下的访问控制,能够有效地避免多域环境下关键权限多分配的问题,能够快速检测出由于域间映射带来安全冲突问题例如:循环继承冲突和角色互斥约束冲突等.
基金Supported by the National High Technology Research and Development Program of China("863"Program)(2006AA12A105)~~
文摘A new safety assessment method for parallel routes is presented. From the aspects of safety guard system of air traffic control（ATC） and considering the flight conflict as causing event of air collision accidents, this paper fosters a four-layer safety guard of controller command, short-term conflict alerts （STCAs）, pilot visual avoidance, and traffic alert collision avoidance system（TCAS）. Then, the problem of parallel routes collision risk is divided into two parts：the calculation of potential flight conflict and the analysis of failure probability of the four-layer safety guard. A calculation model for controller interference times is induced. By using cognitive reliability and error analysis method（CREAM）,the calculation problem to failure probability of controller sequencing flight conflicts is solved and a fault tree model of guard failure of STCA and TCAS is established. Finally, the Beijing-Shanghai parallel routes are taken as an example to be calculated and the collision risk of the parallel routes is obtained under the condition of radar control. Results show that the parallel routes can satisfy the safety demands.
基金The National Natural Science Foundation of China(No.51278220)
文摘Due to the fact that there is no protected signal phase for right turns at most signalized intersections, the conflict between pedestrians and right-turning vehicles is one of the most common conflict types for pedestrians. A pedestrian safety analysis of the common right-turn mode at four-phase signalized intersections is presented. Relative risk is used as a measure of the effect of behaviors. The analysis mainly includes five pedestrian factors that affect the conflict process between pedestrians and right-turning vehicles. Pedestrians tend to have a higher risk of being involved in conflicts in the following six situations: crossing with others, running over the crossing, entering the intersection, being near the exit lane, crossing in the middle or at the end of a green light when the right-turn lane is shared, crossing at the beginning of a green light or red period when the right-turn lane is exclusive. It is easier for pedestrians to get priority when crossing the street in the following situations: running over a crossing, entering the intersection, being near the entrance lane, and not using the crosswalk. However, pedestrians are more inclined to yield to right-turning vehicles when pedestrians are crossing in the middle of the green light time. Some measures to alleviate the conflict are put forward according to the conclusion. Video observations also indicate that a clear pedestrian waiting area must be marked for both pedestrian safety and right-turning vehicle efficiency at major flat intersections, particularly when the arms cover the lateral dividing strips.
文摘How to protect the database, the kernel resources of information warfare, is becoming more and more important since the rapid development of computer and communication technology. As an application-level firewall, database security proxy can successfully repulse attacks originated from outside the network, reduce to zerolevel damage from foreign DBMS products. We enhanced the capability of the COAST' s firewall reference model by adding a transmission unit modification function and an attribute value mapping function,describes the schematic and semantic layer reference model, and finally forms a reference model for DBMS security proxy which greatly helps in the design and implementation of database security proxies. This modeling process can clearly separate the system functionality into three layers, define the possible security functions for each layer, and estimate the computational cost for each layer.
基金Projects(51322810,50908050)supported by the National Natural Science Foundation of China
文摘Comparative analyses were conducted to compare the effects of the behavioral characteristics of the drivers of taxis and private cars on the capacity and safety of signalized intersections. Data were collected at sixteen signalized intersections in the Nanjing area in China. The risk-taking behaviors of the drivers of taxis and private cars were compared. The results suggest that 19.9% of taxi drivers have committed at least one of the identified risky behaviors, which is 2.37 times as high as that of the drivers of private cars(8.4%). The traffic conflicts technique was used to estimate the safety effects of taxis and private cars. The overall conflict rate for taxis is 21.4% higher than that for private cars, implying that taxis are more likely to be involved in conflicts. Almost all of the identified traffic conflicts can be attributed to certain levels of risk-taking behaviors committed by either taxi drivers or the drivers of private cars, and taxi drivers are more likely to be at fault in a conflict. Failure to yield to right-of-way and improper lane change is the leading causes of the conflicts in which taxis are at-fault. The research team further studied the effects of taxis on the queue discharge characteristics at signalized intersections. The results show that the presence of taxis significantly reduces both start-up lost time and saturation headways. The effects of taxis on saturation flow rates are dependent on the proportion of taxis in the discharge flow, and the saturation flow rates increase with the increase in the proportion of taxis. The adjustment factors for various proportions of taxis for different turning movements are then calculated to quantitatively evaluate the effects of taxis on the capacity of signalized intersections.
文摘From June to July of 2017, the approval rates of the Abe administration fell sharply, in stark contrast to the long-term stability since 2012. The stability of Abe＇ s approval rates originated from the people＇ s negative support for him and their opposition to the Security Laws and other important events as well as the scandals under his administration. The opposition and negative support originated from the people＇s ＂acquired helplessness＂, ＂Abenomics＂, the sharp drop in the opporttmity costs of voting and other conditions. The sudden fall of Abe＇ s approval rates was not due to the change in the aforementioned conditions, rather because of the collapse of his image including personality owing to Abe＇ s perceived arrogance and his estrangement with the people. In the context of the temporary stabilization of approval rates, Abe dissolved the House of Representatives ahead of schedule and held a general election, taking full advantage of the internal strife between the opposition parties, to achieve his goal of ruling until the 2020 Tokyo Olympics. His victory in the recent election does not accurately demonstrate that Abe is completely immune to negative impact, thus he will to use the Korean Peninsula crisis and other issues to demonstrate his ability of safeguarding Japan＇s security, seek reconstruction of his image, and further enhance his approval rate to stabilize his administration.
基金under the auspices of Special Research Project for Public Service Sectors of the National Forestry (201004059)National Natural Science Foundation of China (No. 40971282, 40971063)
文摘West China provides important ecological services to the rest of the country, and has attracted great attention because of its serious ecological degradation and frequent natural disasters, and its strong connection with the industrial and economic development in East China. In order to strengthen ecological restoration and promote sustainable economic development in West China, the Chinese government adopted the Western Development Policy, which offered financial aid to and initiated a large number of projects in the region. Although many previous studies have emphasized the positive effects of ecological restoration in West China on ecological security and sustainable development of China, relatively less attention has been paid to analyzing multiple conflicts related to sustainable development in the region. This paper examines the main development goals and interests that have caused these conflicts. The authors suggest that integrated conflict management should be carried out for the sustainable development in West China.
文摘The relation between the United States and the Democratic People＇s Republic of Korea （DPRK） is of substantial strategic prominence in the security landscape of Northeast Asia. The longstanding incompatibility between the two countries can be illuminated by drawing on three factors： the conflict of interest in the DPRK-ROK unification; the strategic interests of the nuclearization and the denuclearization-normalization dilemma; the Sino-U.S. dual power structure in Northeast Asia. In addressing these issues, this paper discusses the possibility of achieving diplomatic normalization between the U.S. and DPRK by examining in a comparative framework the feasibility of existing mechanisms. The paper concludes that unconventional mechanism is required to establish the initial momentum for a necessary political breakthrough, especially in light of the Trump phenomenon. Specifically, the author proposes a stepwise model to assist the diplomatic reconciliation and to further promote the restoration of peace, security and stability in Northeast Asia.
