Dependency Structure Matrix （DSM） is a successful and powerful tool for representing and analyzing dependencies between the items, but for external influencing factors it cannot charge effectively. This paper sets t...Dependency Structure Matrix （DSM） is a successful and powerful tool for representing and analyzing dependencies between the items, but for external influencing factors it cannot charge effectively. This paper sets the stage for connecting the activities and resources, which not only considers information flow but also resources constrains.We first introduce the DSM to represent the degree of overlapping between the activities in a project. Then we present the Extended DSM combined former DSM and resource factors to calculate the project duration. Finally, the practical significance of the Extended DSM is confirmed by an illustrative example.展开更多
This paper proposes a method for planning the three-dimensional path for low-flying unmanned aerial vehicle（UAV） in complex terrain based on interfered fluid dynamical system（IFDS） and the theory of obstacle avoid...This paper proposes a method for planning the three-dimensional path for low-flying unmanned aerial vehicle（UAV） in complex terrain based on interfered fluid dynamical system（IFDS） and the theory of obstacle avoidance by the flowing stream. With no requirement of solutions to fluid equations under complex boundary conditions, the proposed method is suitable for situations with complex terrain and different shapes of obstacles. Firstly, by transforming the mountains, radar and anti-aircraft fire in complex terrain into cylindrical, conical, spherical, parallelepiped obstacles and their combinations, the 3D low-flying path planning problem is turned into solving streamlines for obstacle avoidance by fluid flow. Secondly, on the basis of a unified mathematical expression of typical obstacle shapes including sphere, cylinder, cone and parallelepiped, the modulation matrix for interfered fluid dynamical system is constructed and 3D streamlines around a single obstacle are obtained. Solutions to streamlines with multiple obstacles are then derived using weighted average of the velocity field. Thirdly, extra control force method and virtual obstacle method are proposed to deal with the stagnation point and the case of obstacles＇ overlapping respectively. Finally, taking path length and flight height as sub-goals, genetic algorithm（GA） is used to obtain optimal 3D path under the maneuverability constraints of the UAV. Simulation results show that the environmental modeling is simple and the path is smooth and suitable for UAV. Theoretical proof is also presented to show that the proposed method has no effect on the characteristics of fluid avoiding obstacles.展开更多
文摘针对重叠联盟的合作博弈框架(OCF games)中重叠联盟结构生成(OCSG)求解困难的问题,提出了一种基于贪心方法的有效算法。首先使用了一种带有联盟数量k约束的OCF博弈(kOCF games)模型来限制OCSG问题的规模;然后引入了一种相似度量来表示任意两个联盟结构之间的相似程度,并基于相似度量定义了单调性的性质,这意味着某一联盟结构与最优联盟结构的相似度越高,该联盟的单调性的值就越大;最后对于具有单调性质的kOCF博弈,采用了逐一插入玩家编号以逼近最优联盟结构的方法设计了联盟约束贪心(CCG)算法来求解给定的OCSG问题,并在理论上证明了CCG算法的复杂度是O(n2k+1)。通过实验分析和验证了不同参数和联盟值分布对所提算法性能的影响,并把该算法与Zick等提出的算法(ZICK Y,CHALKIADAKIS G,ELKIND E,et al.Cooperative games with overlapping coalitions:charting the tractability frontier.Artificial Intelligence,2019,271:74-97)在约束条件等方面进行了对比,得出了当联盟最大数量k被常数约束时所提算法的搜索次数随agent的个数基本呈线性增长的结果。可见CCG算法是固定参数k可解的,而且拥有更好的适用性。
基金supported by the National Natural Science Foundation of China under Grant No.71172123the Aviation Science Fund under Grant No.2012ZG53083the Soft Science Foundation of Shaanxi Province and the funds of NPU for Humanities and social sciences and management revilization under Grant No.RW201105
文摘Dependency Structure Matrix （DSM） is a successful and powerful tool for representing and analyzing dependencies between the items, but for external influencing factors it cannot charge effectively. This paper sets the stage for connecting the activities and resources, which not only considers information flow but also resources constrains.We first introduce the DSM to represent the degree of overlapping between the activities in a project. Then we present the Extended DSM combined former DSM and resource factors to calculate the project duration. Finally, the practical significance of the Extended DSM is confirmed by an illustrative example.
基金supported by the National Natural Science Foundation of China(No.61175084)
文摘This paper proposes a method for planning the three-dimensional path for low-flying unmanned aerial vehicle（UAV） in complex terrain based on interfered fluid dynamical system（IFDS） and the theory of obstacle avoidance by the flowing stream. With no requirement of solutions to fluid equations under complex boundary conditions, the proposed method is suitable for situations with complex terrain and different shapes of obstacles. Firstly, by transforming the mountains, radar and anti-aircraft fire in complex terrain into cylindrical, conical, spherical, parallelepiped obstacles and their combinations, the 3D low-flying path planning problem is turned into solving streamlines for obstacle avoidance by fluid flow. Secondly, on the basis of a unified mathematical expression of typical obstacle shapes including sphere, cylinder, cone and parallelepiped, the modulation matrix for interfered fluid dynamical system is constructed and 3D streamlines around a single obstacle are obtained. Solutions to streamlines with multiple obstacles are then derived using weighted average of the velocity field. Thirdly, extra control force method and virtual obstacle method are proposed to deal with the stagnation point and the case of obstacles＇ overlapping respectively. Finally, taking path length and flight height as sub-goals, genetic algorithm（GA） is used to obtain optimal 3D path under the maneuverability constraints of the UAV. Simulation results show that the environmental modeling is simple and the path is smooth and suitable for UAV. Theoretical proof is also presented to show that the proposed method has no effect on the characteristics of fluid avoiding obstacles.
