传感器网络节点定位精度的几何稀释分析

通过分析时间到达(Time of Arrival,TOA)算法的定位原理,利用定位精度的几何稀释(Geometrical Dilution ofPrecision,GDOP),描述定位误差与锚节点群几何布局关系,并给出基于测距的算法中GDOP的计算方法。采用蒙特卡罗仿真方法,仿真次数100,设定锚节点的测距误差相同,取锚节点数为3、5,对基于锚节点群内点、外点的未知节点定位误差的归一化GDOP值和GDOP均值求解,结合质心算法原理,验证了自身节点定位精度与确定该节点位置的锚节点的几何关系密切相关,得到锚节点群内点定位精度高的结论。     

有线电视系统中段电平凸起原因探讨

有线电视网络末端中段电平凸起现象非常普遍，对有线电视信号的传输质量有一定的影响。通常认为均衡特性和频率衰减特性的差异是造成这种现象的主要原因，很难抑制。通过实践和对测试数据的分析，认为电路器件和电缆接头进水是造成这种现象的一个重要原因。     

10kV及以下配电电缆的运行维护

当前我国的电力行业在发展中使用10kV及以下配电电缆的频率较高,而10kV及以下配电电缆在我国的电网建设中的覆盖面积也愈来愈广泛,但是10kV及以下配电电缆在长期的使用中会出现一定的问题,最终影响10kV及以下配电电缆的正常使用,这对于我国电网的运行十分不利,本文将对10kV及以下配电电缆的运行维护问题进行分析,望给相关从业人士提供参考.     

通信电源用电缆及其通信行业标准

本文重点解读通信电源用交联聚烯烃绝缘电缆通信行业标准的主要内容,介绍了交联聚烯烃绝缘的技术特点.评述了聚氯乙烯（PVC）绝缘电缆在环保和安全方面存在的不足.通过比较说明了交联聚烯烃绝缘电缆相对于PVC绝缘电缆和非交联的无卤低烟阻燃聚烯烃绝缘电缆所具有的优势.本文还介绍了低压电缆制造技术,特别是交联工艺路线、电缆料添加剂及电缆料配混技术进展等方面的内容,对未来通信电源用电缆的发展以及标准修改内容提出了建议.     

高级语义信息辅助的无锚框行人检测研究

为了提高车间监控系统智能化程度和工作场景中行人检测精度,提出了一种基于计算机视觉技术的行人检测方法。采用基于高级语义信息的无锚框特征检测技术,将检测任务简化为中心点和尺度的回归预测。特征提取模块通过四阶段降采样卷积网络,得到多尺度的图像特征并融合。头探测模块分成两路卷积,并行处理特征图,获得中心点热力图和尺度信息,输出检测结果。结果表明,在CityPersons数据集R子集上,MR-2达到11.61%,加入偏移量预测分支后MR-2提升了0.6%。这证明了该人员检测方法的性能优良。     

FTTH光缆的结构特点

简要地介绍了FTTH光缆的结构特点.为了便于读者正确选用FTTH光缆,对几种FTTH光缆结构和性能进行了比较详细的阐述.     

Improved SpaceTwist privacy protection method based on anchor optimization algorithm

With location-based services worldwide used,private location data appealed easily in query process which caused serious security problems.So the introduction of SpaceTwist incremental nearest neighbor query algorithm,proposes protection of privacy method combined with improved SpaceTwist location optimization algorithm.The anchor point authentication server added to distributed system structure,user generate a k anonymous area according to their privacy preference and actual environment,using optimization algorithm to generate the anchor point.Forwarding users use the incremental nearest neighbor query throught the anchor point and accurate.Experiments in road network environment with different data sets show that the privacy protection works well in the algorithm,and own high work efficiency.     

Path planning using a mobile anchor node based on trilateration in wireless sensor networks

In wireless sensor networks (WSNs), many applications require sensor nodes to obtain their locations. Now, the main idea in most existing localization algorithms has been that a mobile anchor node (e.g., global positioning system‐equipped nodes) broadcasts its coordinates to help other unknown nodes to localize themselves while moving according to a specified trajectory. This method not only reduces the cost of WSNs but also gets high localization accuracy. In this case, a basic problem is that the path planning of the mobile anchor node should move along the trajectory to minimize the localization error and to localize the unknown nodes. In this paper, we propose a Localization algorithm with a Mobile Anchor node based on Trilateration (LMAT) in WSNs. LMAT algorithm uses a mobile anchor node to move according to trilateration trajectory in deployment area and broadcasts its current position periodically. Simulation results show that the performance of our LMAT algorithm is better than that of other similar algorithms. Copyright © 2011 John Wiley & Sons, Ltd.     

应用三维弹簧系统模型的锚节点部署优化

为使随机部署的三维无线传感器网络中锚节点的分布更加合理,提高未知节点定位精度,针对锚节点部署进行优化。通过构建弹簧系统模型,将锚节点抽象为通过弹簧相连接的点,使部分锚节点在合力作用下进行伸缩运动,达到提高网络性能的目的。当锚节点部署优化完成后,应用近似三角形内点测试( APIT)和DV-HOP( Distance Vector-hop)算法测试优化前后的节点定位精度。仿真结果表明,三维空间下的锚节点经过弹簧系统模型的部署优化后,锚节点网络覆盖率和定位覆盖率均得到了提高,网络平均连通度有所提升,且定位精度显著提高。