Conflict Detection and Resolution（CD＆R） is the key to ensure aviation safety based on Trajectory Prediction（TP）. Uncertainties that affect aircraft motions cause difficulty in an accurate prediction of the trajec...Conflict Detection and Resolution（CD＆R） is the key to ensure aviation safety based on Trajectory Prediction（TP）. Uncertainties that affect aircraft motions cause difficulty in an accurate prediction of the trajectory, especially in the context of four-dimensional（4D） Trajectory-Based Operation（4DTBO）, which brings the uncertainty of pilot intent. This study draws on the idea of time geography, and turns the research focus of CD＆R from TP to an analysis of the aircraft reachable space constrained by 4D waypoint constraints. The concepts of space–time reachability of aircraft and space–time potential conflict space are proposed. A novel pre-CD＆R scheme for multiple aircraft is established. A key advantage of the scheme is that the uncertainty of pilot intent is accounted for via a Space-Time Prism（STP） for aircraft. Conflict detection is performed by verifying whether the STPs of aircraft intersect or not, and conflict resolution is performed by planning a conflict-free space–time trajectory avoiding intersection. Numerical examples are presented to validate the efficiency of the proposed scheme.展开更多
Most transactional memory (TM) research focused on multi-core processors, and others investigated at the clusters, leaving the area of non-uniform memory access (NUMA) system unexplored. The existing TM implementation...Most transactional memory (TM) research focused on multi-core processors, and others investigated at the clusters, leaving the area of non-uniform memory access (NUMA) system unexplored. The existing TM implementations made significant performance degradation on NUMA system because they ignored the slower remote memory access. To solve this problem, a latency-based conflict detection and a forecasting-based conflict prevention method were proposed. Using these techniques, the NUMA aware TM system was presented. By reducing the remote memory access and the abort rate of transaction, the experiment results show that the NUMA aware strategies present good practical TM performance on NUMA system.展开更多
The specification of authorization policies in access control models proposed so far cannot satisfy the requirements in workflow management systems(WFMSs).Furthermore,existing approaches have not provided effective co...The specification of authorization policies in access control models proposed so far cannot satisfy the requirements in workflow management systems(WFMSs).Furthermore,existing approaches have not provided effective conflict detection and resolution methods to maintain the consistency of authorization polices in WFMSs.To address these concerns,we propose the definition of authorization policies in which context constraints are considered and the complicated requirements in WFMSs can be satisfied.Based on the definition,we put forward static and dynamic conflict detection methods for authorization policies.By defining two new concepts,the precedence establishment rule and the conflict resolution policy,we provide a flexible approach to resolving conflicts.展开更多
In order to improve the accuracy of free flight conflict detection and reduce the false alarm rate, an improved flight conflict detection algorithm is proposed based on Gauss-Hermite particle filter（GHPF）. The algor...In order to improve the accuracy of free flight conflict detection and reduce the false alarm rate, an improved flight conflict detection algorithm is proposed based on Gauss-Hermite particle filter（GHPF）. The algorithm improves the traditional flight conflict detection method in two aspects：（i） New observation data are integrated into system state transition probability, and Gauss-Hermite Filter（GHF） is used for generating the importance density function.（ii） GHPF is used for flight trajectory prediction and flight conflict probability calculation. The experimental results show that the accuracy of conflict detection and tracing with GHPF is better than that with standard particle filter. The detected conflict probability is more precise with GHPF, and GHPF is suitable for early free flight conflict detection.展开更多
The conflict detection and resolution in collaborative design is a key issue to maintain multi disciplinary design consistency. This paper proposes a new method for conflict detection and resolution based on constrain...The conflict detection and resolution in collaborative design is a key issue to maintain multi disciplinary design consistency. This paper proposes a new method for conflict detection and resolution based on constraint satisfaction technique. The representation of design constraint, the interval arithmetic of the constraint satisfaction problem CSP and the conflict resolution strategy based on constraint relaxation and adjustment are introduced. A constraint satisfaction based conflict detection and resolution tool CSCDR is then developed. It can help collaborative designers to detect and resolve the conflicts in time in the early stage of the design process so that the unnecessary design iteration and repeated negotiation are avoided and the design efficiency is then much improved. A design case illustrates the effectiveness of CSCDR.展开更多
This paper analyzes conflict features in architecture pipe routing,and builds a pipe routing design conflict model by taking into account of discrete nominal internal diameter selection of pipes,material costs,and con...This paper analyzes conflict features in architecture pipe routing,and builds a pipe routing design conflict model by taking into account of discrete nominal internal diameter selection of pipes,material costs,and conflict solution sequence.Considering pipe routing as an assembling process,a conflict detection approach for pipe routing in collaborative architectural design is proposed based on an aforementioned model.Constraint network is used to describe the relationship among pipe routing design parameters and constraints;design conflicts are detected by matching designers' input and constraint network;and detected design conflicts are reordered according to the number of pipe parameters in conflicts.In order to support the collaborative requirement of pipe routing design,a prototype system using browser/server architecture is developed.An illustrative example of water pipe routing in a room is used to show the effectiveness and efficiency of the approach.展开更多
Engineering-oriented constraint of harness technology has much information and project information presents progressive changes along with the design. Therefore, how to handle conflict resolution quickly is a problem ...Engineering-oriented constraint of harness technology has much information and project information presents progressive changes along with the design. Therefore, how to handle conflict resolution quickly is a problem to be solved. Process model of con- flict detection is put forward according to characteristics of harness technology design engineering-oriented constraint, and then two problems of how to conduct conflict positioning and judgment of constraint rules are introduced in this paper. Afterwards in this pa- per, constraint information directed acyclic graph is established by classified project constraint information to solve the conflict posi- tioning problem; solution of constraint satisfaction problem is applied to realize judgment problem of constraint rules. Finally, exam- ple is used to analyze the method in this paper to further verify the correctness and effectiveness of this method.展开更多
Policy conflicts may cause substantial economic losses.Although a large amount of effort has been spent on detecting intra-domain policy conflict,it can not detect conflicts of heterogeneous policies.In this paper,con...Policy conflicts may cause substantial economic losses.Although a large amount of effort has been spent on detecting intra-domain policy conflict,it can not detect conflicts of heterogeneous policies.In this paper,considering background knowledge,we propose a conflict detection mechanism to search and locate conflicts of heterogeneous policies.First,we propose a general access control model to describe authorization mechanisms of cloud service and a translation scheme designed to translate a cloud service policy to an Extensible Access Control Markup Language(XACML)policy.Then the scheme based on Multi-terminal Multi-data-type Interval Decision Diagram(MTMIDD)and Extended MTMIDD(X-MTMIDD)is designed to represent XACML policy and search the conflict among heterogeneous policies.To reduce the rate of false positives,the description logic is used to represent XACML policy and eliminate false conflicts.Experimental results show the efficiency of our scheme.展开更多
The global view of firewall policy conflict is important for administrators to optimize the policy.It has been lack of appropriate firewall policy global conflict analysis,existing methods focus on local conflict dete...The global view of firewall policy conflict is important for administrators to optimize the policy.It has been lack of appropriate firewall policy global conflict analysis,existing methods focus on local conflict detection.We research the global conflict detection algorithm in this paper.We presented a semantic model that captures more complete classifications of the policy using knowledge concept in rough set.Based on this model,we presented the global conflict formal model,and represent it with OBDD(Ordered Binary Decision Diagram).Then we developed GFPCDA(Global Firewall Policy Conflict Detection Algorithm) algorithm to detect global conflict.In experiment,we evaluated the usability of our semantic model by eliminating the false positives and false negatives caused by incomplete policy semantic model,of a classical algorithm.We compared this algorithm with GFPCDA algorithm.The results show that GFPCDA detects conflicts more precisely and independently,and has better performance.展开更多
To the issues of low efficiency of conflict resolution method in collaborative design, we proposed a method, which is conflict resolution about collaborative design based on grid services.It uses the grid services fro...To the issues of low efficiency of conflict resolution method in collaborative design, we proposed a method, which is conflict resolution about collaborative design based on grid services.It uses the grid services from the current design points, uses the method of retrospective thinking to find the conflict point by detecting, and then uses the corresponding method to resolve the conflict point according to the conflict characteristic, after that carried on the conflict detection again. If there is still the conflict, resolve the conflict point again, until the conflict no longer exists. This method combines various traditional resolution methods, makes full use of the grid idle high-performance large-scale sharing resources. With this method the collaborative design conflict resolution cost reduced and the conflict resolution efficiency was raised. And then the problem which is not handled completely was then solved, so that the conflict resolution Quality was guaranteed.展开更多
Modern day products are usually designed cooperatively by groups of experts, each with his own areas of expertise. Because of different viewpoint, evaluation standard and domain knowledge of these design groups in col...Modern day products are usually designed cooperatively by groups of experts, each with his own areas of expertise. Because of different viewpoint, evaluation standard and domain knowledge of these design groups in collaborative design system, conflict is unavoidable. In this paper, an integration conflict management system (ICMS) was presented from the aspect of all life cycle. A hierarchical constraint network was introduced to detect the conflicts. Three conflict types were classified in ICMS and different type of conflict was submitted to different resolution strategy, constraint relaxation to data conflict and knowlegdge based reasoning to knowledge conflict or schema conflict. To those conflicts hard to be resolved with the above two strategies, an arbitration was used for the conflict resolution. ICMS also provided interface with other collaborative systems such as CAE, CAD to improve the efficiency of collaborative design system.展开更多
In an effort to maintain safety while satisfying growing air traffic demand,air navigation service providers are considering the inclusion of advisory systems to identify potential conflicts and propose resolution com...In an effort to maintain safety while satisfying growing air traffic demand,air navigation service providers are considering the inclusion of advisory systems to identify potential conflicts and propose resolution commands for the air traffic controller to verify and issue to aircraft.To understand the potential workload implications of introducing advisory conflict-detection and resolution tools,this paper examines a metric of controller taskload:how many resolution commands an air traffic controller issues under the guidance of an advisory system.Through a simulation study,the research presented here evaluates how the underlying protocol of a conflict-resolution tool affects the controller taskload(system demands)associated with the conflict-resolution process,and implicitly the controller workload(physical and psychological demands).Ultimately,evidence indicates that there is significant flexibility in the design of conflict-resolution algorithms supporting an advisory system.展开更多
航路交叉口的管制调配一直是影响空管效率的核心问题,以往研究多是针对少量架次航空器进行分析,本论文在航迹运行(trajectory based operations,TBO)环境下,基于自主改航对航路交叉口处交叉航班流的预先冲突解脱方法进行研究.首先,基于...航路交叉口的管制调配一直是影响空管效率的核心问题,以往研究多是针对少量架次航空器进行分析,本论文在航迹运行(trajectory based operations,TBO)环境下,基于自主改航对航路交叉口处交叉航班流的预先冲突解脱方法进行研究.首先,基于航空器间水平安全间隔,转换计算航空器过交叉口时应保持的最小纵向时间间隔;其次,提出占用时间窗概念,建立基于占用时间窗的冲突检测模型,并考虑航班流通过时间最短制定综合通行原则,判定冲突中需要改航的航空器;最后,针对航班流通行中传统启发式算法时效性不足的问题,利用转弯角限制缩减可行解空间,并建立以改航时间最短为目标的改航点搜索模型,提高求解速度和搜索精度.以我国东北部典型高空扇区为例,验证所提方法在实际交叉航路运行下的有效性.仿真结果表明:所提冲突解脱方法的多米诺效应指数(domino effect parameter,DEP)相较于传统等待解脱方法降低了64.7%,且传统方法的解脱总用时为所提冲突解脱方法的7.6倍,所提解脱方法对空域稳定性的影响更小,解脱效率更高.展开更多
基金financial support from the Civil Aviation Joint Funds of the National Natural Science Foundation of China (No’s.U1533203,61179069)
文摘Conflict Detection and Resolution（CD＆R） is the key to ensure aviation safety based on Trajectory Prediction（TP）. Uncertainties that affect aircraft motions cause difficulty in an accurate prediction of the trajectory, especially in the context of four-dimensional（4D） Trajectory-Based Operation（4DTBO）, which brings the uncertainty of pilot intent. This study draws on the idea of time geography, and turns the research focus of CD＆R from TP to an analysis of the aircraft reachable space constrained by 4D waypoint constraints. The concepts of space–time reachability of aircraft and space–time potential conflict space are proposed. A novel pre-CD＆R scheme for multiple aircraft is established. A key advantage of the scheme is that the uncertainty of pilot intent is accounted for via a Space-Time Prism（STP） for aircraft. Conflict detection is performed by verifying whether the STPs of aircraft intersect or not, and conflict resolution is performed by planning a conflict-free space–time trajectory avoiding intersection. Numerical examples are presented to validate the efficiency of the proposed scheme.
基金Projects(61003075, 61170261) supported by the National Natural Science Foundation of China
文摘Most transactional memory (TM) research focused on multi-core processors, and others investigated at the clusters, leaving the area of non-uniform memory access (NUMA) system unexplored. The existing TM implementations made significant performance degradation on NUMA system because they ignored the slower remote memory access. To solve this problem, a latency-based conflict detection and a forecasting-based conflict prevention method were proposed. Using these techniques, the NUMA aware TM system was presented. By reducing the remote memory access and the abort rate of transaction, the experiment results show that the NUMA aware strategies present good practical TM performance on NUMA system.
基金supported by the National Natural Science Foundation of China (Nos.50705084 and 60473129)the Science and Technology Plan of Zhejiang Province,China (No.2007C13018)
文摘The specification of authorization policies in access control models proposed so far cannot satisfy the requirements in workflow management systems(WFMSs).Furthermore,existing approaches have not provided effective conflict detection and resolution methods to maintain the consistency of authorization polices in WFMSs.To address these concerns,we propose the definition of authorization policies in which context constraints are considered and the complicated requirements in WFMSs can be satisfied.Based on the definition,we put forward static and dynamic conflict detection methods for authorization policies.By defining two new concepts,the precedence establishment rule and the conflict resolution policy,we provide a flexible approach to resolving conflicts.
基金Supported by the Joint Project of National Natural Science Foundation of ChinaCivil Aviation Administration of China(U1333116)
文摘In order to improve the accuracy of free flight conflict detection and reduce the false alarm rate, an improved flight conflict detection algorithm is proposed based on Gauss-Hermite particle filter（GHPF）. The algorithm improves the traditional flight conflict detection method in two aspects：（i） New observation data are integrated into system state transition probability, and Gauss-Hermite Filter（GHF） is used for generating the importance density function.（ii） GHPF is used for flight trajectory prediction and flight conflict probability calculation. The experimental results show that the accuracy of conflict detection and tracing with GHPF is better than that with standard particle filter. The detected conflict probability is more precise with GHPF, and GHPF is suitable for early free flight conflict detection.
文摘The conflict detection and resolution in collaborative design is a key issue to maintain multi disciplinary design consistency. This paper proposes a new method for conflict detection and resolution based on constraint satisfaction technique. The representation of design constraint, the interval arithmetic of the constraint satisfaction problem CSP and the conflict resolution strategy based on constraint relaxation and adjustment are introduced. A constraint satisfaction based conflict detection and resolution tool CSCDR is then developed. It can help collaborative designers to detect and resolve the conflicts in time in the early stage of the design process so that the unnecessary design iteration and repeated negotiation are avoided and the design efficiency is then much improved. A design case illustrates the effectiveness of CSCDR.
基金Supported by the National High Technology Research and Development Programme of China(No.2006AA04Z112)the National Natural Science Foundation of China(No.51175287)the National S&T Major Program(No.2009ZX02001-003)
文摘This paper analyzes conflict features in architecture pipe routing,and builds a pipe routing design conflict model by taking into account of discrete nominal internal diameter selection of pipes,material costs,and conflict solution sequence.Considering pipe routing as an assembling process,a conflict detection approach for pipe routing in collaborative architectural design is proposed based on an aforementioned model.Constraint network is used to describe the relationship among pipe routing design parameters and constraints;design conflicts are detected by matching designers' input and constraint network;and detected design conflicts are reordered according to the number of pipe parameters in conflicts.In order to support the collaborative requirement of pipe routing design,a prototype system using browser/server architecture is developed.An illustrative example of water pipe routing in a room is used to show the effectiveness and efficiency of the approach.
基金Supported by Chinese national Science Foundation (No.61070124)the Fundamental Research Funds for the Central Universities(No.2012HGBZ0195)
文摘Engineering-oriented constraint of harness technology has much information and project information presents progressive changes along with the design. Therefore, how to handle conflict resolution quickly is a problem to be solved. Process model of con- flict detection is put forward according to characteristics of harness technology design engineering-oriented constraint, and then two problems of how to conduct conflict positioning and judgment of constraint rules are introduced in this paper. Afterwards in this pa- per, constraint information directed acyclic graph is established by classified project constraint information to solve the conflict posi- tioning problem; solution of constraint satisfaction problem is applied to realize judgment problem of constraint rules. Finally, exam- ple is used to analyze the method in this paper to further verify the correctness and effectiveness of this method.
基金This work has been funded by the National Natural Science Foundation of China(No.U1836203)the Shandong Provincial Key Research and Development Program(2019JZZY20127).
文摘Policy conflicts may cause substantial economic losses.Although a large amount of effort has been spent on detecting intra-domain policy conflict,it can not detect conflicts of heterogeneous policies.In this paper,considering background knowledge,we propose a conflict detection mechanism to search and locate conflicts of heterogeneous policies.First,we propose a general access control model to describe authorization mechanisms of cloud service and a translation scheme designed to translate a cloud service policy to an Extensible Access Control Markup Language(XACML)policy.Then the scheme based on Multi-terminal Multi-data-type Interval Decision Diagram(MTMIDD)and Extended MTMIDD(X-MTMIDD)is designed to represent XACML policy and search the conflict among heterogeneous policies.To reduce the rate of false positives,the description logic is used to represent XACML policy and eliminate false conflicts.Experimental results show the efficiency of our scheme.
基金supported by the National Nature Science Foundation of China under Grant No.61170295 the Project of National ministry under Grant No.A2120110006+2 种基金 the Co-Funding Project of Beijing Municipal Education Commission under Grant No.JD100060630 the Beijing Education Committee General Program under Grant No. KM201211232010 the National Nature Science Foundation of China under Grant NO. 61370065
文摘The global view of firewall policy conflict is important for administrators to optimize the policy.It has been lack of appropriate firewall policy global conflict analysis,existing methods focus on local conflict detection.We research the global conflict detection algorithm in this paper.We presented a semantic model that captures more complete classifications of the policy using knowledge concept in rough set.Based on this model,we presented the global conflict formal model,and represent it with OBDD(Ordered Binary Decision Diagram).Then we developed GFPCDA(Global Firewall Policy Conflict Detection Algorithm) algorithm to detect global conflict.In experiment,we evaluated the usability of our semantic model by eliminating the false positives and false negatives caused by incomplete policy semantic model,of a classical algorithm.We compared this algorithm with GFPCDA algorithm.The results show that GFPCDA detects conflicts more precisely and independently,and has better performance.
基金the National High Technology Research and Development Program of China (863 Program) (2002AA414060, 2001AA411310)the Key Science and Technology Program of Shaanxi Province (2006K05- G10)
文摘To the issues of low efficiency of conflict resolution method in collaborative design, we proposed a method, which is conflict resolution about collaborative design based on grid services.It uses the grid services from the current design points, uses the method of retrospective thinking to find the conflict point by detecting, and then uses the corresponding method to resolve the conflict point according to the conflict characteristic, after that carried on the conflict detection again. If there is still the conflict, resolve the conflict point again, until the conflict no longer exists. This method combines various traditional resolution methods, makes full use of the grid idle high-performance large-scale sharing resources. With this method the collaborative design conflict resolution cost reduced and the conflict resolution efficiency was raised. And then the problem which is not handled completely was then solved, so that the conflict resolution Quality was guaranteed.
文摘Modern day products are usually designed cooperatively by groups of experts, each with his own areas of expertise. Because of different viewpoint, evaluation standard and domain knowledge of these design groups in collaborative design system, conflict is unavoidable. In this paper, an integration conflict management system (ICMS) was presented from the aspect of all life cycle. A hierarchical constraint network was introduced to detect the conflicts. Three conflict types were classified in ICMS and different type of conflict was submitted to different resolution strategy, constraint relaxation to data conflict and knowlegdge based reasoning to knowledge conflict or schema conflict. To those conflicts hard to be resolved with the above two strategies, an arbitration was used for the conflict resolution. ICMS also provided interface with other collaborative systems such as CAE, CAD to improve the efficiency of collaborative design system.
基金funded by NASA(No.NNX08AY52A)FAA Award(No.07-C-NEGIT)+1 种基金Amendment(Nos.005,010,020)Air Force Contract(No.FA9550-08-1-0375)。
文摘In an effort to maintain safety while satisfying growing air traffic demand,air navigation service providers are considering the inclusion of advisory systems to identify potential conflicts and propose resolution commands for the air traffic controller to verify and issue to aircraft.To understand the potential workload implications of introducing advisory conflict-detection and resolution tools,this paper examines a metric of controller taskload:how many resolution commands an air traffic controller issues under the guidance of an advisory system.Through a simulation study,the research presented here evaluates how the underlying protocol of a conflict-resolution tool affects the controller taskload(system demands)associated with the conflict-resolution process,and implicitly the controller workload(physical and psychological demands).Ultimately,evidence indicates that there is significant flexibility in the design of conflict-resolution algorithms supporting an advisory system.
文摘航路交叉口的管制调配一直是影响空管效率的核心问题,以往研究多是针对少量架次航空器进行分析,本论文在航迹运行(trajectory based operations,TBO)环境下,基于自主改航对航路交叉口处交叉航班流的预先冲突解脱方法进行研究.首先,基于航空器间水平安全间隔,转换计算航空器过交叉口时应保持的最小纵向时间间隔;其次,提出占用时间窗概念,建立基于占用时间窗的冲突检测模型,并考虑航班流通过时间最短制定综合通行原则,判定冲突中需要改航的航空器;最后,针对航班流通行中传统启发式算法时效性不足的问题,利用转弯角限制缩减可行解空间,并建立以改航时间最短为目标的改航点搜索模型,提高求解速度和搜索精度.以我国东北部典型高空扇区为例,验证所提方法在实际交叉航路运行下的有效性.仿真结果表明:所提冲突解脱方法的多米诺效应指数(domino effect parameter,DEP)相较于传统等待解脱方法降低了64.7%,且传统方法的解脱总用时为所提冲突解脱方法的7.6倍,所提解脱方法对空域稳定性的影响更小,解脱效率更高.
