On the hop-constrained survivable network design problem with reliable edges

In this paper, we study the hop-constrained survivable network design problem with reliable edges. Given a graph with non-negative edge costs and node pairs Q, the hop-constrained survivable network design problem consists of constructing a minimum cost set of edges so that the induced subgraph contains at least K edge-disjoint paths containing at most L edges between each pair in Q. In addition, we consider here a subset of reliable edges that are not subject to failure. We study two variants: a static problem where the reliability of edges is given, and an upgrading problem where edges can be upgraded to the reliable status at a given cost. We adapt for the two variants an extended formulation proposed in Botton, Fortz, Gouveia, Poss (2011) [1] for the case without reliable edges. As before, we use Benders decomposition to accelerate the solving process. Our computational results indicate that these two variants appear to be more difficult to solve than the original problem (without reliable edges). We conclude with an economical analysis which evaluates the incentive of using reliable edges in the network.     

PDH数字微波链路性能监控的设计

针对PDH数字微波传输系统中存在的链路性能难监控这个问题,引入Radio Hop和Radio Link链路监控点的概念,采用PLR算法（Packet-Lost-Recognition）对监控点的数据进行分析处理,获得相关的误码性能事件SES、BBE、ES、UAS。当传输质量下降时,根据这些事件发出相应的告警消息,使工作人员能够及时地了解故障原因并进行处理。     

基于信道化谱增强的混合DS/FH扩频信号跳速估计

该方法首先利用非线性变换获得携带跳速信息的参考信号,并利用循环谱预估计该信号的频率集;在此基础上,提出一种新的信道化谱增强系统。该系统所具有的外在线性内在非线性(ELIN)特性能够在防止信号失真的前提下有效克服噪声及干扰对后续时频分析的影响;最后,通过SPWVD(平滑伪Wigner-Ville分布)实现精确的跳速估计。该算法无需信号的先验知识,并易于通信侦测接收机实现。仿真实验证明了该算法在低信噪比下对跳速估计的有效性。     

Optimal transmission power with delay constraints in 2D and 3D MANETs

Given the mobile node (MN) density and transmission power, this paper estimates the per-hop advancement toward destination with a single transmission, assuming that MNs are uniformly distributed. Based on this esteem, we calculate required hop count between two given MNs. In homogeneous mobile ad hoc networks (MANETs) where all MNs utilize the same transmission power, the hop count between any two MNs is proportional to the distance between them. Given the distance between each pair of MNs, this paper suggests the optimal transmission range (OTR) of MNs, which is the minimum possible power to guarantee end-to-end delay constraints of requested connections in the entire network. Packet collision is also considered in computing the OTR. All problems are investigated in both a two-dimensional (2D) and a three-dimensional (3D) area. Simulation results substantiate the accuracy of proposed estimation methods. The errors of the per-hop advancement estimation are just 0.88% and 2.33% in a 2D and 3D areas.     

Evaluation of quality of service provisioning in large-scale pervasive and smart collaborative wireless sensor and actor networks

With the production of low cost sensors, classical concept of Wireless Sensor Networks (WSNs) evolved into large-scale concept hosting thousands of nodes within a network and generating abundant quantities of data. As these networks are being continuously developed a new class of WSNs are proposed: Wireless Sensor and Actor Networks (WSANs). These networks introduce the actuating component, alongside with the sensing component, where QoS is becoming a very significant factor. The authors of this paper approach the problem of QoS support in large-scale WSAN from a physical layer, where the deployment parameters effects on QoS metrics are demystified. The analysis is formulated on two scenarios: worst case scenario (all nodes transmit data towards the network sink) and best case scenario (a single node transmits a stream of data towards a network sink). For both scenarios two routing protocols were compared, a simple flooding algorithm and a simple distance vector protocol. Also, a new relation between hop count and latency based on transmission power is observed, not reported in the available literature, resulting in a new proposed empirical latency model.     

基于分享度的最小连通支配集求解算法

以节点分享度作为选择分配点的优先级,提出一种最小连通支配集(CDS)求解算法.从根节点开始,将具有局部最大分享度的节点作为支配点,选择连接点与已确定的支配点连通,逐步构造网络的支配树,分析支配树的直径,计算支配树的平均跳数距离(AHD),从而评价网络的通信成本.实验结果表明,与CDS-BD-C2算法相比,该算法得到的CDS规模较小,且支配树的AHD平均减少12％.     

MPLS中的工作路由和后备路由确定算法

为提高网络资源的利用率,在基于Local故障恢复方案的前提下,提出了一种路由算法,这种算法在确定工作LSP的同时也确定好后备LSP,并使工作路由和后备路由带宽之和最小。     

一种改进的无线传感器网络DV-Hop定位算法在煤矿井下漏电事故中的应用

煤矿井下输电线路的实时监测中,漏电故障定位是供电系统保护的重要研究课题。针对井下无线传感器网络定位算法存在不准确的问题,提出了一种改进DV-Hop节点定位算法。首先通过计算锚节点组成的三角形面积,排除面积极小的锚节点组,避免锚节点近似共线的情况,完成了锚节点的优选方案;此外在粒子群算法的基础上结合遗传算法和混沌理论,提出了一种遗传混沌粒子群优化算法;最后利用改进的粒子群算法对DV-Hop算法定位得到的节点位置进行校正。经过仿真实验表明在相同的网络环境下,与传统DV-Hop算法相比,改进算法能够更有效地提高定位精度,从而更加准确地监测到煤矿井下漏电事故位置。     

超临界萃取技术及其在啤酒花浸膏生产上的应用

随着科学技术的发展,超临界流体萃取技术以其独特的优势越来越受到人们的关注。对超临界流体萃取技的发展概况、原理、应用以及未来发展做了简单介绍,并着重叙述了其在啤酒花浸膏的生产过程中的应用。     

Xanthohumol,a prenylated chalcone from Humulus lupulus L., inhibits cholesteryl ester transfer protein

High density lipoprotein (HDL)-cholesterol levels are correlated with a low risk of atherosclerosis. The inhibition of cholesteryl ester transfer protein (CETP), which catalyses cholesterol transfer between lipoproteins, leads to an increase in HDL-cholesterol and is expected to be the next anti-atherogenic target. This study revealed that xanthohumol, a prenylated chalcone, showed the highest inhibition against CETP from screening of natural products in various plants. We investigated the inhibitory activity of some chalcones and flavanones. Naringenin chalcone showed weak CETP inhibition compared with xanthohumol. In addition, isoxanthohumol and naringenin drastically decreased the inhibitory activity. These results suggest that the prenyl group and chalcone structure of xanthohumol were responsible for the CETP inhibitory activity.