On a stochastic sensor selection algorithm with applications in sensor scheduling and sensor coverage

In this note we consider the following problem. Suppose a set of sensors is jointly trying to estimate a process. One sensor takes a measurement at every time step and the measurements are then exchanged among all the sensors. What is the sensor schedule that results in the minimum error covariance? We describe a stochastic sensor selection strategy that is easy to implement and is computationally tractable. The problem described above comes up in many domains out of which we discuss two. In the sensor selection problem, there are multiple sensors that cannot operate simultaneously (e.g., sonars in the same frequency band). Thus measurements need to be scheduled. In the sensor coverage problem, a geographical area needs to be covered by mobile sensors each with limited range. Thus from every position, the sensors obtain a different view-point of the area and the sensors need to optimize their trajectories. The algorithm is applied to these problems and illustrated through simple examples.     

面向无线传感器网络应用的传感器技术综述

无线传感器网络是目前国内外研究的一个热点方向,具有非常广泛的应用前景,其应用与发展,将对人类的生活和生产的各个领域带来深刻的影响.对目前已经应用于无线传感器网络的具体传感器技术进行了分析,总结了无线传感器网络应用对传感器技术的需求约束.依据这些需求展望了未来可能应用于无线传感器网络的传感器技术.     

以传感器为视点的无线传感器网络节点设计趋势综述

无线传感器网络节点是无线传感器网络组成的基本单元,节点的软硬件设计在整个无线传感器网络的构建中举足轻重.在研究了大量无线传感器网络节点的基础上,对节点模型结构进行了分析,在讨论模型中各模块相互关系的同时,重点讨论了传感器模块与其它模块关系,综述了无线传感器网络节点的发展情况,预测了未来节点发展的趋势.     

基于改进DV-HOP的道路交通拥堵传感节点快速监测

由于现有交通拥堵监控设备在海量三维交通信息中处理数据的能力较差,导致监测目标延迟较高,故设计一种基于改进DV-HOP的道路交通拥堵传感节点快速监测方法;在待监测区域安置无线视觉传感器,划分子节点与Sink节点,采集车辆通行状况和整体长度;把异常道路数据作为小概率事件,确立速率采集周期及交通状态采集周期,推算历史车辆速率均值和交通数据方差,设定拥堵临界值,分析路段是否产生拥堵;对道路交通拥堵节点进行初始化,确定全部道路交通拥堵节点,并将其转换到二维坐标中;利用改进DV-HOP算法获取道路交通拥堵节点位置信息,得出道路交通拥堵节点监测结果;实验分析表明：设计方法的均等系数值可达0.998,数据传输延时仅为3.5 s,表明交通拥堵监测精度较高。     

基于无线传感器网络的水质监测系统设计

在研究无线传感器网络及Zigbee协议标准的基础上,对远程实时水质监测系统进行了分析.提出了基于Zigbee无线传感器网络与互联网结合的远程实时水质监测系统架构.设计了基于无线传感器的水质监测网络体系结构,实现了水质监测参数的荻取及传输.     

Fibre Bragg gratings in structural health monitoring—Present status and applications

In-service structural health monitoring (SHM) of engineering structures has assumed a significant role in assessing their safety and integrity. Fibre Bragg grating (FBG) sensors have emerged as a reliable, in situ, non-destructive tool for monitoring, diagnostics and control in civil structures. The versatility of FBG sensors represents a key advantage over other technologies in the structural sensing field. In this article, the recent research and development activities in structural health monitoring using FBG sensors have been critically reviewed, highlighting the areas where further work is needed. A few packaging schemes for FBG strain sensors are also discussed. Finally a few limitations and market barriers associated with the use of these sensors have been addressed.     

基于动态权重的传感网络路径选择算法仿真

在传感器网络路径选择过程中,网络路径选择具有较高的动态性,导致传统采用流体神经网络算法,依据单一标准明确属性权重,无法针对变化的网络属性进行有效分析,不能得到有效的网络路径.提出了一种采用动态权重的传感网络路径选择算法,根据层次分析法确认不同业务状态下各网络路径属性的重要性,选取带宽、时延、抖动、丢包率四个属性作为网络路径选择的判决准则,构建属性的判断矩阵,采用特征根法计算不同判断属性的权重,按照业务类型动态调整权重,明确各属性的综合权重,采用灰色关联分析方法明确不同备选网络路径的灰色关联系数,对备选网络路径进行加权排序,进而选择最佳传感网络路径.仿真结果验证了所提方法选择路径过程中的收敛迭代次数以及有效解数量都优于传统方法,并且所提方法下的传感网络具有较高的数据传输效率.     

BP神经网络信息融合技术在水质监控中的应用

目前我国对于集约化水产养殖的水质调控,仅处于单指标调节水平,忽略了水质因子间的相互作用对养殖环境产生的影响。本文在现有的多传感器无线传感网络基础上,构建基于BP神经网络的信息融合监控系统,对多元非线性水质因子进行信息融合以全面评估当前水质环境是否适合虾类生长并做出相应的调控决策。文章最后通过实际水质数据对该系统算法进行测试分析,测试结果表明此监控系统具有较高的精确度,为集约化水质监控开辟了一条新路径。     

基于ZigBee无线传感网络空气质量监测系统的实现

随着社会不断地发展进步,环保作为当今研究的热点问题,而空气质量监测已经成为公众关注的焦点,对空气中的污染物进行定点、连续或定时的采样和测量,并将监测结果发送到监控中心,加以分析并得到相关的数据进行分析。基于ZigBee无线传感网络空气质量监测是一种典型的无线传感器网络应用。采取实时监控,以便快速分析空气质量及成分,能迅速定位污染源,以便采取有力措施进行污染干预。     

基于无线传感器网络及GPRS的水质监测系统设计

提出了一种基于ZigBee无线传感器网络和GPRS技术的多参数远程实时水质监测系统;无线传感器网络以CC2430通信模块为核心,传感器节点采集到的数据经路由节点汇总至协调器节点,通过GPRS模块及时远传至监控中心,设计信号调理电路,将传感器电极输出的微弱电信号进行放大、滤波,采用时间同步机制实现网络节点的同步唤醒,大幅提高网络的稳定性;对系统进行了多天连续测试,通信距离为100m时,网络的平均丢包率低于1%,pH值、溶氧度的平均相对偏差低于1%;测试结果表明,系统具有灵活、实时性好、准确性高、稳定可靠等优点,具有很强的实用价值。     

Tracking a moving object via a sensor network with a partial information broadcasting scheme

Tracking a moving object is one of the key applications of wireless sensor networks (WSNs) for facility management, logistics, healthcare, etc. The quantitative relationship between tracking accuracy and resource consumption is crucial for designing a WSN-based tracking system. A partial information broadcasting scheme (PIBS) is developed as a decentralized tracking strategy in this paper, where only a part of the nodes broadcast their tracking estimation results to their neighbors. The relationship between tracking accuracy and resource consumption is quantified with this scheme. Two broadcasting policies are proposed by balancing the residual energy among sensors and reducing time delay, where the “Randomly Broadcast” (RB) policy takes energy consumption as a first priority and the “Good Estimates Broadcast First” (GEBF) policy consider time delay first. Both of them can be implemented as a decentralized tracking strategy. It is shown that the PIBS with RB or PIBS with GEBF can reduce required resources with minor degradation in tracking accuracy in comparison with the centralized tracking strategy. The finite sensing range of a sensor node is considered and a node activation scheme with variable activation radius is introduced for energy saving. The activation radius is adjusted to guarantee tracking coverage with trade-off between tracking accuracy and resource consumption. The analytical conditions on tracking coverage and the bounds on tracking accuracy are obtained. The numerical experiments demonstrate that this activation scheme outperforms the existing schemes.     

语义传感器Web中的数据管理技术研究

语义传感器Web是由传感器网络技术、分布式计算技术、数据库管理技术和语义Web技术整合发展而来的.语义传感器Web能够感知、收集、整合信息,抽取新的知识并为感知器提供增强语义,因此能对环境的变化有更智能的感知,用户可以通过访问Web获取这些信息.作为计算机科学中一个新的研究领域,它有着广阔的应用前景,引起了工业界和学术界浓厚的兴趣.介绍了语义传感器Web的基本概念、特点,并着重讨论了语义传感器Web数据管理中所存在的研究问题、研究现状和研究成果.     

基于无线传感器网络的鱼塘水质监测系统

针对传统水质监测系统在水质参数在线监测、预警能力、数据精度和稳定性方面的不足,综合使用无线传感器网络、GPRS无线通信、GSM短信等技术与方法,构建一个鱼塘水质远程实时监测系统。该系统具有预警及时、响应迅速、形象化查询、可扩展性强等特点。     

基于ZigBee技术的医院供水管网水质监控系统

针对医院供水管网水质问题,设计了基于ZigBee无线传感器网络的水质实时监控系统。监控系统由末端的不同传感器采集水温、pH值、电导率水质参数,通过ZigBee无线网络传送给网关,网关实现ZigBee和TcP/IP协议间的转换后,将数据传送给监控中心进行存储、分析和处理,监控中心可发送命令控制整个网络。该方案不仅可以实现本地和远程水质实时监控,而且很容易应用于其他环境下的水质实时监控。     

基于无线传感网络的水质在线移动监测系统

针对静态离线水质监测方法存在采样误差大、监测频次低、监测数据分散以及无法实时反馈水质状况的连续动态变化等问题,研发了基于无线传感网络的水质在线移动监测系统.该系统由水下监测器、浮标节点和可视化软件组成.水下监测器模仿金枪鱼外观设计,内部装备水质传感器(温度、pH、浊度和电导率等)用于获取水质参数信息;浮标节点采用太阳能...     

Design and evaluation of a device worn for fall detection and localization: Application for the continuous monitoring of risks incurred by dependents in an Alzheimer’s care unit

The Homecare project, which is part of a research project funded by the French National Research Agency (ANR), aims to define a new multi-sensor monitoring system for the elderly with cognitive disabilities in a care unit. Two subjects were recruited to participate to experimental trials. The main objective of this project is to design and test a complete monitoring system at a real site. It is a new clinical and technical approach which is complex to implement: Homecare is intended to propose a possible technical solution, demonstrate its feasibility and illustrate its use working at a protected site. The system consists of a motion sensor network deployed on the ceiling to monitor motion and an electronic patch worn by the subjects to identify them and detect falls. In order to locate tagged subjects inside the care unit, a network of anchor points is used. From these positions and movement data, an analysis algorithm detects an abnormal situation and alerts the nursing staff in real time. A Web application allows the medical staff to access movements and alarms. The complete monitoring system has been functioning for several months and continuously monitors two patients around the clock. In this paper, we present the implementation of the system, the method of localization inside the care unit, and the characterization of the fall detector, and we show certain results relating to activity data.     

An effective node-selection scheme for the energy efficiency of solar-powered WSNs in a stream environment

Previous research on scheduling and solar power issues of wireless sensor networks (WSNs) assumes that the sensors are deployed in a general environment. While monitoring the stream environment, sensors are attached to the stream side to collect the sensed data and transmit the data back to the sink. The stream environment can be scaled in several similar environments. This type of geographic limitation not only exists in a stream environment but also on streets, roads, and trails. This study presents an effective node-selection scheme to enhance the efficiency of saving power and coverage of solar-powered WSNs in a stream environment. Analysis of the sensor deployment in the stream environment permits sensors to be classified into different segments, and then allows the selection of active nodes for building inter-stream connections, inter-segment connections, and intra-segment connections. Based on these connections, the number of active nodes and transmitted packets is minimized. Simulation results show that this scheme can significantly increase the energy efficiency and maintain the monitoring area in solar-powered WSNs.     

A statistical analysis of interference and effective deployment strategies for facility-specific wireless sensor networks

Sensors are essential to industrial automation as they provide vital links between control systems and the physical world. Recently, wireless sensor networks (WSNs) attract more attention as they become feasible solutions for facility management. Unlike simulated environments, however, there are challenges in developing reliable WSNs for monitoring real facilities, including reduced accuracy, reliability and performance due to unpredictable interferences. This paper investigates deployment of automation facility-specific WSNs, called facility sensor networks (FSNs). First, interferences at multiple sensing nodes are analyzed to see if FSNs are vulnerable to interference. Second, interference sources are identified by applying statistical methods to collected data, in order to find the appropriate FSN configuration. Finally, an interference model is proposed to obtain optimal deployment strategies that minimize influence of interference. The strategy yields the lowest interference level compared to others. The results also suggest the appropriate number of sensors to be deployed.