Ambient Assisted Living(AAL) is becoming an important research field. Many technologies have emerged related with pervasive computing vision, which can give support for AAL. One of the most reliable approaches is base...Ambient Assisted Living(AAL) is becoming an important research field. Many technologies have emerged related with pervasive computing vision, which can give support for AAL. One of the most reliable approaches is based on wireless sensor networks(WSNs). In this paper, we propose a coverage-aware unequal clustering protocol with load separation(CUCPLS) for data gathering of AAL applications based on WSNs. Firstly, the coverage overlap factor for nodes is introduced that accounts for the degree of target nodes covered. In addition, to balance the intra-cluster and inter-cluster energy consumptions, different competition radiuses of CHs are computed theoretically in different rings, and smaller clusters are formed near the sink. Moreover, two CHs are selected in each cluster for load separation to alleviate the substantial energy consumption difference between a single CH and its member nodes. Furthermore, a backoff waiting time is adopted during the selection of the two CHs to reduce the number of control messages employed. Simulation results demonstrate that the CUCPLS not only can achieve better coverage performance, but also balance the energy consumption of a network and prolong network lifetime.展开更多
This paper presents an innovative eccentric jacket substructure for offshore wind turbines to better withstand intense environmental forces and to replace conventional X-braced jackets in seismically active areas. The...This paper presents an innovative eccentric jacket substructure for offshore wind turbines to better withstand intense environmental forces and to replace conventional X-braced jackets in seismically active areas. The proposed eccentric jacket comprises of completely overlapped joint at every joint connection. The joint consists of a chord and two braces in a single plane. The two braces are fully overlapped with a short segment of the diagonal brace welded directly onto the chord. The characteristic feature of this joint configuration is that the short segment member can be designed to absorb and dissipate energy under cyclic load excitation. The experimental and numerical study revealed that the completely overlapped joint performed better in terms of strength resistance, stiffness, ductility, and energy absorption capacity than the conventional gap joints commonly found in typical X-braced jacket framings. The eccentric jacket could also be designed to becoming less stiff, with an inelastic yielding and local buckling of short segment member, so as to better resist the cyclic load generated from intense environmental forces and earthquake. From the design economics, the eccentric jacket provided a more straightforward fabrication with reduced number of welded joints and shorter thicker wall cans than the conventional X-braced jacket. It can therefore be concluded based on the results presented in the study that by designing the short segment member in accordance with strength and ductility requirement,the eccentric jacket substructure supporting the wind turbine could be made to remain stable under gravity loads and to sustain a significantly large amount of motion in the event of rare and intense earthquake or environmental forces, without collapsing.展开更多
海洋数据同化是一种同时利用海洋观测资料和海洋数值模式对海洋数据进行修正的有效方法,经过处理的海洋数据更加接近海洋的真实情况.在高分辨率下,基于中国科学院大气物理研究所(Institute of Atmospheric Physics,Chinese Academy of S...海洋数据同化是一种同时利用海洋观测资料和海洋数值模式对海洋数据进行修正的有效方法,经过处理的海洋数据更加接近海洋的真实情况.在高分辨率下,基于中国科学院大气物理研究所(Institute of Atmospheric Physics,Chinese Academy of Sciences,IAP)和大气科学和地球流体力学数值模拟国家重点实验室(State Key Laboratory Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics,LASG)发展的LASG/IAP气候系统海洋模式(LASG/IAP climate ocean model,LICOM)的同化并行程序往往涉及大量的文件读取、通信和计算,以往的研究虽然对这些方面进行了优化,但是由于优化只是停留在上层算法层面,没有考虑底层的文件系统以及超算集群的架构,因此优化的效果不太明显.针对以往研究存在的问题,进一步将海洋数据同化的数据特性、计算特性与所使用的超算平台的架构特性相结合,在此基础上结合时间局部性和空间局部性,提出了基于计算拓扑图的负载均衡策略、基于Lustre文件存储架构和超算集群特性的并行优化策略,以及计算、读取通信、写回3层重叠策略.最后,使用高分辨率数据集,在天河2号超算集群上对所提算法进行了测试.相比于现有算法,所提的算法在4 000核下对总体同化性能上提升了18倍.另外,还在曙光7 000超算集群上开展了测试.在4 000块DCU加速卡上,相比于已有算法,所提算法提升总体计算性能8倍左右.展开更多
基金supported by the National Nature Science Foundation of China (61170169, 61170168)
文摘Ambient Assisted Living(AAL) is becoming an important research field. Many technologies have emerged related with pervasive computing vision, which can give support for AAL. One of the most reliable approaches is based on wireless sensor networks(WSNs). In this paper, we propose a coverage-aware unequal clustering protocol with load separation(CUCPLS) for data gathering of AAL applications based on WSNs. Firstly, the coverage overlap factor for nodes is introduced that accounts for the degree of target nodes covered. In addition, to balance the intra-cluster and inter-cluster energy consumptions, different competition radiuses of CHs are computed theoretically in different rings, and smaller clusters are formed near the sink. Moreover, two CHs are selected in each cluster for load separation to alleviate the substantial energy consumption difference between a single CH and its member nodes. Furthermore, a backoff waiting time is adopted during the selection of the two CHs to reduce the number of control messages employed. Simulation results demonstrate that the CUCPLS not only can achieve better coverage performance, but also balance the energy consumption of a network and prolong network lifetime.
文摘This paper presents an innovative eccentric jacket substructure for offshore wind turbines to better withstand intense environmental forces and to replace conventional X-braced jackets in seismically active areas. The proposed eccentric jacket comprises of completely overlapped joint at every joint connection. The joint consists of a chord and two braces in a single plane. The two braces are fully overlapped with a short segment of the diagonal brace welded directly onto the chord. The characteristic feature of this joint configuration is that the short segment member can be designed to absorb and dissipate energy under cyclic load excitation. The experimental and numerical study revealed that the completely overlapped joint performed better in terms of strength resistance, stiffness, ductility, and energy absorption capacity than the conventional gap joints commonly found in typical X-braced jacket framings. The eccentric jacket could also be designed to becoming less stiff, with an inelastic yielding and local buckling of short segment member, so as to better resist the cyclic load generated from intense environmental forces and earthquake. From the design economics, the eccentric jacket provided a more straightforward fabrication with reduced number of welded joints and shorter thicker wall cans than the conventional X-braced jacket. It can therefore be concluded based on the results presented in the study that by designing the short segment member in accordance with strength and ductility requirement,the eccentric jacket substructure supporting the wind turbine could be made to remain stable under gravity loads and to sustain a significantly large amount of motion in the event of rare and intense earthquake or environmental forces, without collapsing.
文摘海洋数据同化是一种同时利用海洋观测资料和海洋数值模式对海洋数据进行修正的有效方法,经过处理的海洋数据更加接近海洋的真实情况.在高分辨率下,基于中国科学院大气物理研究所(Institute of Atmospheric Physics,Chinese Academy of Sciences,IAP)和大气科学和地球流体力学数值模拟国家重点实验室(State Key Laboratory Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics,LASG)发展的LASG/IAP气候系统海洋模式(LASG/IAP climate ocean model,LICOM)的同化并行程序往往涉及大量的文件读取、通信和计算,以往的研究虽然对这些方面进行了优化,但是由于优化只是停留在上层算法层面,没有考虑底层的文件系统以及超算集群的架构,因此优化的效果不太明显.针对以往研究存在的问题,进一步将海洋数据同化的数据特性、计算特性与所使用的超算平台的架构特性相结合,在此基础上结合时间局部性和空间局部性,提出了基于计算拓扑图的负载均衡策略、基于Lustre文件存储架构和超算集群特性的并行优化策略,以及计算、读取通信、写回3层重叠策略.最后,使用高分辨率数据集,在天河2号超算集群上对所提算法进行了测试.相比于现有算法,所提的算法在4 000核下对总体同化性能上提升了18倍.另外,还在曙光7 000超算集群上开展了测试.在4 000块DCU加速卡上,相比于已有算法,所提算法提升总体计算性能8倍左右.
