In this paper, an evolutionary model of bus transport network in B-space is developed. It includes the effect of the overlapping ratio of new route on network performance and overcomes the disadvantage, i.e. lack of e...In this paper, an evolutionary model of bus transport network in B-space is developed. It includes the effect of the overlapping ratio of new route on network performance and overcomes the disadvantage, i.e. lack of economic consideration, in the evolutionary bus transport network model in P-space proposed by Chen et al （2007）. The degree distribution functions are derived by using the mean-field method and the master equation method, separately. The relationship between the new stop ratio of a route, λ, and the error in exponential of degree distribution function from the mean-field method is developed as ASlope= λ/（1 -λ） ＋ ln（1-λ）. Finally, the bus transport networks of Hangzhou and Nanjing are simulated by using this model, and the results show that some characteristic index values of the simulated networks are closer to the empirical data than those from Chen＇s model.展开更多
虚拟管道宽度直接影响了管道内无人机的流速,但目前虚拟管道规划的方法并不能保证管道宽度,容易造成堵塞,严重影响无人机通行效率。对此,提出一种虚拟管道空间满足规划方法,可以在包含障碍物的环境中得到一条满足虚拟管道空间要求的管...虚拟管道宽度直接影响了管道内无人机的流速,但目前虚拟管道规划的方法并不能保证管道宽度,容易造成堵塞,严重影响无人机通行效率。对此,提出一种虚拟管道空间满足规划方法,可以在包含障碍物的环境中得到一条满足虚拟管道空间要求的管道生成线。主要包括路径搜索和轨迹优化,基于快速探索随机树*(rapidly exploring random tree*,RRT*)搜索,通过空间检测判断每段路径周围是否有足够空间,若无足够空间则重新拓展搜索,替换掉空间不足的路径段。在轨迹优化过程中,使用均匀B样条参数化轨迹,并设计碰撞代价函数和光滑代价函数,使轨迹远离障碍物,为虚拟管道规划提供足够空间。仿真测试验证了所提方法在大规模集群中的优越性和鲁棒性。在仿真测试中,15架无人机集群通行时间平均降低20%。展开更多
基金supported by the National Natural Science Foundation of China (Grant No 70571033)the State Key Development Program for Basic Research of China (Grant No 2006CB705500)
文摘In this paper, an evolutionary model of bus transport network in B-space is developed. It includes the effect of the overlapping ratio of new route on network performance and overcomes the disadvantage, i.e. lack of economic consideration, in the evolutionary bus transport network model in P-space proposed by Chen et al （2007）. The degree distribution functions are derived by using the mean-field method and the master equation method, separately. The relationship between the new stop ratio of a route, λ, and the error in exponential of degree distribution function from the mean-field method is developed as ASlope= λ/（1 -λ） ＋ ln（1-λ）. Finally, the bus transport networks of Hangzhou and Nanjing are simulated by using this model, and the results show that some characteristic index values of the simulated networks are closer to the empirical data than those from Chen＇s model.
文摘虚拟管道宽度直接影响了管道内无人机的流速,但目前虚拟管道规划的方法并不能保证管道宽度,容易造成堵塞,严重影响无人机通行效率。对此,提出一种虚拟管道空间满足规划方法,可以在包含障碍物的环境中得到一条满足虚拟管道空间要求的管道生成线。主要包括路径搜索和轨迹优化,基于快速探索随机树*(rapidly exploring random tree*,RRT*)搜索,通过空间检测判断每段路径周围是否有足够空间,若无足够空间则重新拓展搜索,替换掉空间不足的路径段。在轨迹优化过程中,使用均匀B样条参数化轨迹,并设计碰撞代价函数和光滑代价函数,使轨迹远离障碍物,为虚拟管道规划提供足够空间。仿真测试验证了所提方法在大规模集群中的优越性和鲁棒性。在仿真测试中,15架无人机集群通行时间平均降低20%。
