摘要：Visible-Light Communication(VLC) has the potential to provide dense and fast connectivity at low cost. In this paper we propose SFNet, a novel VLC-enabled hybrid data center network that extends the design of wireless Data Center Networks(DCNs) into three further dimensions:(1) fully wireless at the inter-rack level;(2) no need for a centralized control mechanism on wireless links;and(3) no need for any infrastructure-level alterations to data centers. Previous proposals typically cannot realize these three rationales simultaneously. To achieve this vision,the proposed SFNet augments fat-tree by organizing all racks into a wireless small-world network via VLC links. The use of VLC links eliminates hierarchical switches and cables in the wireless network, and thus reduces hardware investment and maintenance costs. To fully exploit the benefits of the topology of SFNet, we further propose its topology design and optimization method, routing scheme, and online flow scheduling algorithm. Comprehensive experiments indicate that SFNet exhibits good topological properties and network performance.

摘要：The visible light communication (VLC) has the potential to provide dense and fast connectivity at low cost. In this paper, we propose a novel VLC enabled Wireless Small-World Data Center (WSWDC). It employs VLC links to achieve a fully wireless data center network (DCN) across racks for the first time. The using of VLC links eliminates hierarchical switches and inter-rack cables, and thus reducing hardware investment, as well as maintenance cost. More precisely, to simplify the configuration and control operations, we propose three DCN design rationales:(1) fully-wireless, all inter-rack links are wireless;(2) easy-deployable, it is not necessary to change the existing infrastructure inside data center;(3) plug-and-play, no extra centralized control operations are required. Previous proposals, however, cannot achieve the three rationales simultaneously. To this end, we first use regular VLC links to interconnect racks as a regular grid DCN and optimize the rack placement to shorten the average path length and the network diameter. To further exploiting the benefits of VLC links, a few random VLC links are carefully introduced to update the wireless grid DCN as a wireless small-world DCN. To avoid the potential interference among VLC links, we deploy VLC transceivers at different heights on the top of each rack. In this way, VLC links would not interfere with others at each height level. Moreover, we design a greedy but efficient routing method for any pair of racks using their identifiers as inputs. Comprehensive evaluation results indicate that our WSWDC exhibits good topological properties and network performance.

摘要：近年来,提出的以服务器为中心的新型数据中心网络互连结构部分程度地解决了传统树型结构面临的性能瓶颈和可扩展性难题,同时出现了以集装箱为基本模块构建超大规模的数据中心.然而,如何设计模块之间的互连结构,确保数据中心网络具有高可扩展性、模块之间具有高带宽是一个非常具有挑战性的问题.以BCube为代表的新型数据中心网络,能够将数千台服务器互连在一个集装箱内,且对各种典型流量模式提供较高的带宽.提出了一种常量度数的模块之间的互连结构***基于BCube结构进行模块内服务器互连,利用模块内大量未被使用的上行端口,在各个模块保持常量度数的情况下,能够保证模块之间具有高可扩展性,同时模块之间具有较高的带宽.

摘要：虽然以服务器为中心的新型数据中心网络互联结构部分一般程度地解决了传统树型结构面临的性能瓶颈和可扩展性难题,但是,现行服务器大多数带有2个网络端口,如何基于双网卡服务器设计一种高可扩展、高性能的数据中心网络互联结构是一个颇具挑战性的问题.提出了基于双网卡服务器的高效可扩展数据中心网络互联结构***具有较高的网络吞吐量,使得数据中心能够进行无损和持续扩展,各类应用能够不受数据中心规模扩展的影响而继续运行;且服务器之间通过交换机进行互联,避免了服务器之间的直接连线,具有良好的模块化性.

摘要：全球信息网格采用面向服务的架构提高系统的可重用性、柔性设计能力以及按需快速构建能力。这些优势的充分发挥需要快速及时发现各类可用的数据和服务。该文提出了两种扩展性很好的分布式服务发现机制:面向完全自治UDDI注册中心的非结构化UDDI对等网络和面向协同UDDI注册中心的结构化UDDI对等网络。

摘要：针对伊拉克某油田所面临的现场施工设备采购难、施工设备简陋等问题,基于组合法创新设计原理,就地取材,研制了一种结构紧凑、操作便捷、缠绕质量佳的新型管道防腐胶带缠绕机。提出的由低速电动套丝机带动管道旋转做主运动的新型缠绕方式,改善了传统缠绕机悬挂于管道外壁螺旋前进带来的胶带贴合不一致、缠绕质量不佳等问题。现场应用表明:该设备能有效解决现场施工效率低,工人劳动强度大等问题。

摘要：编程实验对于深化学生对数据科学课程知识点的理解意义重大。传统的编程实验没有按照模块化设计,存在代码体量大、知识点考查针对性不强的问题。一方面,这导致学生在面对较大代码量的编程作业时难以入手,不同知识点也没有得到有针对性的训练;另一方面,教师难以精确评价学生的知识点掌握情况。运用模块化设计方法来设计编程实验,能够有效解决这些问题,提升教学效果。

摘要：为了提高机载远程激光测距机接收系统设计的可行性,从激光测距方程出发,分析了最小探测灵敏度与测程的关系。对回波频谱特性、探测模块带宽和放大器带宽进行了仿真,计算了回波信号的放大倍数,推算出主放大器输出信号的大小。依据高斯白噪声模型和主放大器输出信号值,推算了激光测距接收电路的最大允许输入噪声值。设计了电路并进行了试验测试。结果表明,激光接收灵敏度与理论值的偏差为5. 7%,消光比法对应空中小目标最大测程与理论值的偏差仅为1. 5%。该噪声分析方法对机载远程激光测距机的接收系统设计具有一定的指导意义。