Towards efficient device-to-device multicast content delivery with social awareness

Frequent content retrieval leads to significant energy consumption in cellular networks. Thereby, device-to-device (D2D) communication is used for proximal content delivery. Be aware that social friends may have common content interests, D2D content delivery is further improved by considering social network. However, how to implement efficient D2D multicast with the aid of social relationship needs further consideration. In this paper, with a proposed architecture on combined networks, the cooperation range of content sharing is investigated for D2D multicast to minimize the average energy consumption of serving a content request. Based on combined networks, a cooperation group formation scheme is proposed. Simulation results verify our analyzes and the advantage of proposed scheme.     

Inrush current estimation and hot-swapping for safe parallel battery pack

ABSTRACT

Batteries used in electric vehicles and microgrid applications use battery modules connected in series to satisfy the voltage required for each system, and battery modules are connected in parallel to increase capacity. In this parallel connected system, in order to disconnect and reconnect a specific battery module or to reconnect a new battery module, the battery module to be newly connected should have a small state of charge (SOC) difference from the existing battery modules. In particular, when a new battery is to be connected under a load current, there is a problem that excessive inrush current may occur in a specific battery module due to the load current distributed to each module and the current due to the SOC difference. Therefore, in this paper, we propose a method of estimating the inrush current through an equivalent electrical modelling analysis for the case where a battery module is newly added in a system in which the battery modules are connected in parallel. In addition, the power management algorithm for the battery pack system with inrush current estimation is presented. The proposed method is validated through simulations and experiments of a battery pack system in which 10 battery modules of 710V and 120Ah are connected in parallel.     

The Reliability of Groundwater Sources to Meet Increasing Demands

The groundwater resources of the Lee Valley Water Company have been examined in a joint study with the University of Birmingham. The Company is modifying its operating policy to make maximum use of the groundwater resources, which has involved the development of new methods of estimating the reliable output of the groundwater sources under differing conditions. The technology transfer involved in the project has enabled the Company to gain a greater understanding of the operation of its sources, and the University has modified existing techniques so that they are of greater practical use.     

高层建筑结构舒适度的模糊可靠性分析及设计

根据模糊集和截集的概念，将模糊可靠性设计问题转化为常规可靠性设计问题。利用此观点对高层建筑结构的舒适度进行了模糊可靠性分析及设计研究。     

应急情况下最少转发节点的传感器网络组播路由树算法

在抢险救灾等应急情况下,传感器网络的节点能量更为有限。为减少无用转发的能量消耗,利用无线信道的广播特性,根据广播子树删除思想,提出一种基于最短路由树、具有最少转发节点的组播路由树生成算法。对该算法进了证明和详细分析,并针对实际需要,给出使用范围更广泛的分布式实现方法。仿真分析说明,算法的分布式实现方法可减少ODMRP的转发节点数,大大降低数据发送次数,接收成员节点较多时尤为明显。最少转发节点的组播路由树的网络总开销最小,是延长网络生存时间的有效方法。     

一种基于IP的适于数据中心网络的高速通信协议的设计

设计了一种C/S结构的、基于IP的自定义快速文件传输协议CFFTP (customized fast file transport protocol)协议,简述了协议交互流程,以及协议的软件实现流程。该协议能充分利用数据中心局域网下的丰富带宽资源,实现数据、文件的可靠快速传输。仿真结果显示,数据传输速率可达近10Gbps的线速,实验结果显示,虽然受到Server端磁盘文件读取速度的影响,数据传输速率仍然可以达到6Gbps的最高速率。     

永磁同步电机参数辨识研究综述

永磁同步电机(permanent magnet synchronous motor,PMSM)参数的实时准确获取,是实现PMSM高性能控制、可靠状态监控的重要前提和早期故障诊断的有效手段,为此,PMSM参数辨识技术获得众多学者的广泛研究关注且取得了长足发展,呈现出大量的研究和应用成果。该文在对既有文献归纳梳理的基础上,首先分析PMSM参数变化的原因,总结PMSM单参数和多参数辨识的技术成果,再对PMSM辨识方法进行归纳和比较,最后,揭示PMSM参数辨识过程中亟需关注的研究问题并展望其未来的发展方向,旨在实现PMSM系统的高效可靠运行。     

卫星集群IP多播组呼业务协议研究

现有集群通信覆盖范围有限,为实现全方位集群通信,提出将卫星通信与集群通信相结合。以TETRA为例,分析了现有国内外集群通信系统集群业务的实现方式。针对电路域集群,提出实现分组域多媒体集群。为更利于工程实现,提出了基于MBMS技术的卫星集群IP多播组呼业务协议流程,并分析了实现中需要解决的关键问题及解决方案。该方案将为卫星移动通信集群业务的发展提供新的方向。     

一种星载IP交换机队列管理器的设计

针对星载IP交换机中硬件存储资源使用受限的情况,提出了一种适用于共享存储交换结构、存储资源占用少的队列管理器。通过添加索引的方法,使得所有的单播队列能够共享一个指针存储区。根据位图映射,将组播指针转化为多个单播指针,即可把组播操作的数据流按照单播操作方式写到相应的逻辑队列路径,达到节约存储器资源的目的。该队列管理器通过链表数据结构的头部和尾部来控制指针索引的写入和输出。最后,在Xilinx的xc6vlx130t FPGA进行了综合实现,结果显示,该方案相比基于指针复制的队列管理器,在8端口的交换机中存储器资源的使用量要节约22%以上。