针对数据中心网络中传统多径路由方法易造成大象流(Elephant flow)冲突,进而导致网络链路拥塞等问题,文中提出了一种基于粒子群优化的动态负载均衡机制(Dynamic load balancing mechanism based on particle swarm optimization,DLB-PSO...针对数据中心网络中传统多径路由方法易造成大象流(Elephant flow)冲突,进而导致网络链路拥塞等问题,文中提出了一种基于粒子群优化的动态负载均衡机制(Dynamic load balancing mechanism based on particle swarm optimization,DLB-PSO)。该机制结合SDN具有全局网络拓扑信息可视化等技术优势,基于粒子群优化算法,根据当前网络链路资源状态等信息,以最小化最大链路利用率为优化目标,为大象流计算出最佳传输路径。实验结果表明,相比于传统的等价多径路由(Equal-cost multi-path routing,ECMP)、全局优先匹配(Global first fit,GFF)及面向SDN的LABERIO机制,文中提出的机制能够更加有效地改善网络吞吐量,降低流的时延抖动。展开更多
针对云计算环境下的高能耗问题,从系统节能的角度提出一种节能资源调度算法(energy-saving scheduling algorithm based on min-max,ESSAMM)。在Min-Max算法的基础上综合考虑了用户对于任务期望的完成时间和能量消耗两个因素,以节省任...针对云计算环境下的高能耗问题,从系统节能的角度提出一种节能资源调度算法(energy-saving scheduling algorithm based on min-max,ESSAMM)。在Min-Max算法的基础上综合考虑了用户对于任务期望的完成时间和能量消耗两个因素,以节省任务执行过程中产生的能量消耗,并提高用户的时间QoS满意度,实现负载均衡。将任务集合中各任务按照长度从小到大排序,并根据时间QoS为该集合中长度最大和最小的任务选出符合用户期望的物理资源;根据能量估算模型,计算出这两个任务在各物理机上的执行能耗;选择最小能耗对应的物理机来执行该任务;将这两个任务在任务集合中删除,并重复上述过程,直到任务集合为空。仿真结果表明,相比于Min-Max和Min-Min资源调度算法,该算法能够有效降低系统执行任务产生的总能耗,提高用户时间服务质量,并实现调度系统负载均衡。展开更多
High Temperature Steam Electrolysis (HTSE) through a solid oxide electrolytic cell (SOEC) has been receiving increasing research and development attention worldwide because of its high conversion efficiency (about 45%...High Temperature Steam Electrolysis (HTSE) through a solid oxide electrolytic cell (SOEC) has been receiving increasing research and development attention worldwide because of its high conversion efficiency (about 45%-59%) and its potential usage for large-scale production of hydrogen. The mechanism, composition, structure, and developing challenges of SOEC are summarized. Current situation, key materials, and core technologies of SOEC (solid oxide electrolytic cell) in HTSE are re- viewed, and the prospect of HTSE future application in advanced energy fields is proposed. In addition, the recent research achievements and study progress of HTSE in Tsinghua University are also intro- duced and presented.展开更多
Hydrogen generation through thermal chemical water splitting technology has recently received in- creasingly international interest in the nuclear hydrogen production field. Besides the main known sulfur-iodine (S-I) ...Hydrogen generation through thermal chemical water splitting technology has recently received in- creasingly international interest in the nuclear hydrogen production field. Besides the main known sulfur-iodine (S-I) cycle developed by the General Atomics Company and the UT3 cycle (iron, calcium, and bromine) developed at the University of Tokyo, the thermal cycle based on metal oxide two-step water splitting methods is also receiving research and development attention worldwide. In this work, copper ferrite was prepared by the co-precipitation method and oxygen-deficient copper ferrite was synthesized through first and second calcination steps for the application of hydrogen production by a two-step water splitting process. The crystal structure, properties, chemical composition and δ were investigated in detail by utilizing X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA), atomic absorption spectrometer (AAS), ultraviolet spectrophotometry (UV), gas chro- matography (GC), and so on. The experimental two-step thermal chemical cycle reactor for hydrogen generation was designed and developed in this lab. The hydrogen generation process of water splitting through CuFe2O4-δ and the cycle performance of copper ferrite regeneration were firstly studied and discussed.展开更多
文摘针对数据中心网络中传统多径路由方法易造成大象流(Elephant flow)冲突,进而导致网络链路拥塞等问题,文中提出了一种基于粒子群优化的动态负载均衡机制(Dynamic load balancing mechanism based on particle swarm optimization,DLB-PSO)。该机制结合SDN具有全局网络拓扑信息可视化等技术优势,基于粒子群优化算法,根据当前网络链路资源状态等信息,以最小化最大链路利用率为优化目标,为大象流计算出最佳传输路径。实验结果表明,相比于传统的等价多径路由(Equal-cost multi-path routing,ECMP)、全局优先匹配(Global first fit,GFF)及面向SDN的LABERIO机制,文中提出的机制能够更加有效地改善网络吞吐量,降低流的时延抖动。
文摘针对云计算环境下的高能耗问题,从系统节能的角度提出一种节能资源调度算法(energy-saving scheduling algorithm based on min-max,ESSAMM)。在Min-Max算法的基础上综合考虑了用户对于任务期望的完成时间和能量消耗两个因素,以节省任务执行过程中产生的能量消耗,并提高用户的时间QoS满意度,实现负载均衡。将任务集合中各任务按照长度从小到大排序,并根据时间QoS为该集合中长度最大和最小的任务选出符合用户期望的物理资源;根据能量估算模型,计算出这两个任务在各物理机上的执行能耗;选择最小能耗对应的物理机来执行该任务;将这两个任务在任务集合中删除,并重复上述过程,直到任务集合为空。仿真结果表明,相比于Min-Max和Min-Min资源调度算法,该算法能够有效降低系统执行任务产生的总能耗,提高用户时间服务质量,并实现调度系统负载均衡。
基金Supported by the specialized research fund for the Doctoral Program of Higher Education (Grant No. 20070003033)
文摘High Temperature Steam Electrolysis (HTSE) through a solid oxide electrolytic cell (SOEC) has been receiving increasing research and development attention worldwide because of its high conversion efficiency (about 45%-59%) and its potential usage for large-scale production of hydrogen. The mechanism, composition, structure, and developing challenges of SOEC are summarized. Current situation, key materials, and core technologies of SOEC (solid oxide electrolytic cell) in HTSE are re- viewed, and the prospect of HTSE future application in advanced energy fields is proposed. In addition, the recent research achievements and study progress of HTSE in Tsinghua University are also intro- duced and presented.
基金the specialized research fund for the Doctoral Program of Higher Education, Ministry of Education of China (Grant No. 20070003033)
文摘Hydrogen generation through thermal chemical water splitting technology has recently received in- creasingly international interest in the nuclear hydrogen production field. Besides the main known sulfur-iodine (S-I) cycle developed by the General Atomics Company and the UT3 cycle (iron, calcium, and bromine) developed at the University of Tokyo, the thermal cycle based on metal oxide two-step water splitting methods is also receiving research and development attention worldwide. In this work, copper ferrite was prepared by the co-precipitation method and oxygen-deficient copper ferrite was synthesized through first and second calcination steps for the application of hydrogen production by a two-step water splitting process. The crystal structure, properties, chemical composition and δ were investigated in detail by utilizing X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA), atomic absorption spectrometer (AAS), ultraviolet spectrophotometry (UV), gas chro- matography (GC), and so on. The experimental two-step thermal chemical cycle reactor for hydrogen generation was designed and developed in this lab. The hydrogen generation process of water splitting through CuFe2O4-δ and the cycle performance of copper ferrite regeneration were firstly studied and discussed.
