基于SDN(software defined networking)体系结构的迭代式负载均衡与节能的流调度算法(load balancing and energy saving flow scheduling with iteration,LoadbE-it)在实现负载均衡的同时最高可节约25%左右的能耗,但其时间复杂度为O(n ...基于SDN(software defined networking)体系结构的迭代式负载均衡与节能的流调度算法(load balancing and energy saving flow scheduling with iteration,LoadbE-it)在实现负载均衡的同时最高可节约25%左右的能耗,但其时间复杂度为O(n 4),不利于在大规模网络中部署。LoadbE-it-M算法(load balancing and energy saving flow scheduling with iteration multiple)通过逐步减少网络拓扑中需要计算的链路数量来提升运行效率。理论和实验结果表明,LoadbE-it-M算法不仅具有较小的计算开销,并且与LoadbE-it算法具有同样的负载均衡能力和节能效果。展开更多
Purpose-Isometric feature mapping(Isomap)is a very popular manifold learning method and is widely used in dimensionality reduction and data visualization.The most time-consuming step in Isomap is to compute the shorte...Purpose-Isometric feature mapping(Isomap)is a very popular manifold learning method and is widely used in dimensionality reduction and data visualization.The most time-consuming step in Isomap is to compute the shortest paths between all pairs of data points based on a neighbourhood graph.The classical Isomap(C-Isomap)is very slow,due to the use of Floyd’s algorithm to compute the shortest paths.The purpose of this paper is to speed up Isomap.Design/methodology/approach-Through theoretical analysis,it is found that the neighbourhood graph in Isomap is sparse.In this case,the Dijkstra’s algorithm with Fibonacci heap(Fib-Dij)is faster than Floyd’s algorithm.In this paper,an improved Isomap method based on Fib-Dij is proposed.By using Fib-Dij to replace Floyd’s algorithm,an improved Isomap method is presented in this paper.Findings-Using the S-curve,the Swiss-roll,the Frey face database,the mixed national institute of standards and technology database of handwritten digits and a face image database,the performance of the proposed method is compared with C-Isomap,showing the consistency with C-Isomap and marked improvements in terms of the high speed.Simulations also demonstrate that Fib-Dij reduces the computation time of the shortest paths from O(N3)to O(N2lgN).Research limitations/implications-Due to the limitations of the computer,the sizes of the data sets in this paper are all smaller than 3,000.Therefore,researchers are encouraged to test the proposed algorithm on larger data sets.Originality/value-The new method based on Fib-Dij can greatly improve the speed of Isomap.展开更多
文摘基于SDN(software defined networking)体系结构的迭代式负载均衡与节能的流调度算法(load balancing and energy saving flow scheduling with iteration,LoadbE-it)在实现负载均衡的同时最高可节约25%左右的能耗,但其时间复杂度为O(n 4),不利于在大规模网络中部署。LoadbE-it-M算法(load balancing and energy saving flow scheduling with iteration multiple)通过逐步减少网络拓扑中需要计算的链路数量来提升运行效率。理论和实验结果表明,LoadbE-it-M算法不仅具有较小的计算开销,并且与LoadbE-it算法具有同样的负载均衡能力和节能效果。
基金supported by the National Natural Science Foundation of China under Grant Nos 91220301,61273314 and 61175064.
文摘Purpose-Isometric feature mapping(Isomap)is a very popular manifold learning method and is widely used in dimensionality reduction and data visualization.The most time-consuming step in Isomap is to compute the shortest paths between all pairs of data points based on a neighbourhood graph.The classical Isomap(C-Isomap)is very slow,due to the use of Floyd’s algorithm to compute the shortest paths.The purpose of this paper is to speed up Isomap.Design/methodology/approach-Through theoretical analysis,it is found that the neighbourhood graph in Isomap is sparse.In this case,the Dijkstra’s algorithm with Fibonacci heap(Fib-Dij)is faster than Floyd’s algorithm.In this paper,an improved Isomap method based on Fib-Dij is proposed.By using Fib-Dij to replace Floyd’s algorithm,an improved Isomap method is presented in this paper.Findings-Using the S-curve,the Swiss-roll,the Frey face database,the mixed national institute of standards and technology database of handwritten digits and a face image database,the performance of the proposed method is compared with C-Isomap,showing the consistency with C-Isomap and marked improvements in terms of the high speed.Simulations also demonstrate that Fib-Dij reduces the computation time of the shortest paths from O(N3)to O(N2lgN).Research limitations/implications-Due to the limitations of the computer,the sizes of the data sets in this paper are all smaller than 3,000.Therefore,researchers are encouraged to test the proposed algorithm on larger data sets.Originality/value-The new method based on Fib-Dij can greatly improve the speed of Isomap.
