A system for ubiquitous fall monitoring at home via a wireless sensor network and a wearable mote

Accidental falls of our elderly, and physical injuries resulting, represent a major health and economic problem. Falls are the most common cause of serious injuries and are a major health threat in the stratum of older population. Early detection of a fall is a key factor when trying to provide adequate care to elderly person who has suffered an accident at home. Therefore, the detection of falls in the elderly remains a major challenge in the field of public health. Specific actions aimed at the fall detection can provide urgent care which allows, on the other hand, drastically reduce the cost of medical care, and improve primary care service. In this paper, we present a support system for detecting falls of an elder person by the combination of a wearable wireless sensor node based on an accelerometer and a static wireless non-intrusive sensory infrastructure based on heterogeneous sensor nodes. This previous infrastructure called DIA (Dispositivo Inteligente de Alarma, in Spanish) is an AAL (Ambient Assisted Living) system that allows to infer a potential fall. This inference is reinforced for prompt attention by a specific sensorisation at portable node sensor in order to help distinguish between falls and daily activities of assisted person. The wearable node will not determine a falling situation, it will advice the reasoner layer about specific acceleration patterns that could, eventually, imply a falling. Is at the higher layer where the falling is determined from the whole context produced by mesh of fixed nodes. Experimental results have shown that the proposed system obtains high reliability and sensitivity in the detection of the fall.     

温湿度检测的无线传感器网络

介绍了用于温湿度检测的无线传感器网络的设计,讨论了传感器节点的温湿度测量原理、电源特征和通信模式。该系统稳定性好,通信效率高,可广泛应用于环境检测。     

Highly sensitive humidity sensor at low humidity based on the quaternized polypyrrole composite film

Polypyrrole composite was fabricated by using chemical polymerization at room temperature, which was further quaternized with 1,4-bromobutane to prepare the humidity sensitive material. The electrical properties of the sensor were measured. The results showed that the quaternized polypyrrole composite film exhibited low impedance at very low humidity; the impedance value was about 780 kΩ at 11% RH and the impedance changed from 10⁶ to 10³ Ω between 11% and 95% RH, which was suitable for detection of low humidity. Moreover, the logarithm of impedance of the polypyrrole composite film varied linearly (R² = 0.9916) with relative humidity in the range of 11–95% RH. Surface and cross-sectional morphology of the films, response–recovery time and hysteresis were also measured and estimated. The sensing mechanism of the sensor was also investigated.     

基于无线传感网络的远程水环境中参数实时监测

针对目前水环境污染状况的日益恶化的问题,采用无线传感器网络,通过节点传感器采集水环境中离子浓度、盐度、电导率、温度等参数来实现实时监测。传感器网络节点一跳或多跳方式自组织网络,汇聚节点将传感器网络节点采集的数据通过GSM/GPRS发送至上位机。上位机对数据进行分析处理,实现对水环境中各项参数的实时监测。实验表明该系统具有成本低廉、移植性好、实时性强的效果。     

基于光栅传感器的穿戴式呼吸监测系统设计

基于呼吸感应体积描记(RIP)技术原理,将一条穿戴式内部嵌入光栅条的弹性缚带系在患者胸腔或者腹腔,由于呼吸时会产生的体积变化,引起弹性缚带中光栅条的位置变化,通过光栅传感器对光栅条位置变化进行精确检测,可以实现对呼吸过程的监测.采用单片机对传感器信号进行存储传输,利用智能终端计算出呼吸频率和通气量.通过网络实现了对呼吸状态的远程存储、对比、分析及监护.通过9名测试者的实验对比分析,证明了本系统测量精度高、工作性能良好,抗干扰能力强.     

基于数据聚合的无线传感器网络拓扑发现算法

针对传感器网络能源有限的特性,提出了一种基于数据聚合的拓扑发现算法。根据在聚合节点（sink）收集到网络内部节点报文接收或丢失的情况,通过发现网络中所有叶子节点到sink节点的数据传输路径,来推测网络的逻辑拓扑,不会增加网络负担。仿真实验表明：算法可以准确快速地推测传感器网络的拓扑,并且适合大规模传感网络的拓扑推测。     

Humidity sensor based on LiCl-doped ZnO electrospun nanofibers

The humidity sensitive characteristics of sensors fabricated from pure ZnO nanofibers and LiCl-doped ZnO composite fibers by screen-printing on ceramic substrates with carbon interdigital electrodes have been investigated. The best result is obtained for 1.2 wt% LiCl-doped sample, which exhibits high humidity sensitivity, rapid response and recovery, small hysteresis, excellent linearity, and good reproducibility. The impedance of the sensor varies more than four orders of magnitude during the whole relative humidity (RH) from 11 to 95%. The response time and recovery time of the sensor is about 3 and 6 s, respectively. These results make our product a good candidate in fabricating high performance humidity sensors.     

基于ZigBee无线传输的倾角传感器网络

应用ZigBee传感器节点的硬件和软件以及上位机软件研制了一种无线倾角传感器网络系统.采用了二次温度补偿解决温度对测量精度的影响,并对无线网络的功耗进行了优化处理.实验表明:该系统的测量精度达到了±0.01°(倾角测量范围为±3 °),数据采集间隔为1次/s时,平均电流仅为0.21 mA,达到了高精度低功耗的设计要求.     

基于传感器网络的智慧酒店系统研究

酒店需要提升其智慧经营、服务和控制的能力。通过对相关企业调研,以及对传感器网络技术的应用研究和实验,得出,在酒店构建ZigBee的应用网络,采用无线传感器网络技术,在多媒体接入控制（MAC）层上执行IEEE802.11e升级标准,可以实现酒店4级优先业务管理模式。使酒店在构建第三方软件信息融合的平台上,进行统一信号处理、存储、计算与反馈,满足智慧服务和控制的应用需求。     

基于网络编码的无线传感器网络数据可靠性分析*

分析了网络编码在提高无线传感器网络数据传输可靠性的途径,并在不同的数据传输路径方式下应用网络编码进行数据传输。在使用网络编码的多路径传输中,提出一种新的传输机制,通过选择源节点的编码数据包数,在对可靠性影响较小的情况下,降低冗余数据包的数量。通过理论分析和计算机模拟给出了网络编码在不同的传输路径下对数据可靠性的效益,得出在数据传输率较高或适中时,在单路径传输下使用网络编码的可靠性优于不使用网络编码的可靠性。     

基于智能手机传感网的室内老年监护系统平台

针对老年人监护需求的日益增长,提出了一种基于手机麦克风传感网络的监护平台设计。该平台利用搭载麦克风的智能设备进行音频信号采集,以Wi-Fi作为基础网络,支撑上层MQTT物联网协议传输数据与指令,并将基于能量比的声学几何定位算法作为监控的核心功能。首先使用Matlab仿真实验证实了定位原理的合理性和算法的可行性;然后对四部异质Android设备进行麦克风特性测试并修正算法参数;最后搭建了测试平台,实验表明此平台达到了可用的定位精度。     

基于GPSO-DVHop的传感器节点定位方法

为了减少无线传感器网络节点的定位误差,提出一种分群粒子群优化（GPSO）算法修正DV-Hop误差的传感器节点定位方法（GPSO-DVHop）。提出一种节点距离修正值策略,减少未知节点与锚节点间距离的估计误差,采用GPSO算法修正DV-Hop的节点定位误差,最后在Matlab 2012平台上对算法性能仿真分析。相对于对比传感器定位方法,GPSO-DVHop提高了传感器节点定位精度,仿真结果验证了GPSO-DVHop的有效性。     

无线传感器网络安全存在的问题和对策

无线传感器网络是一种全新的信息获取和处理技术,由于其通常自行的运作,不需要人员进行职守,因此无线传感器网络的安全存在较大的威胁,本文在无线传感器网络潜在威胁的基础上,从物理层、链路层和路由层三个方面,对无线传感器网络安全存在的问题和对策,进行了深入的研究,希望能给实际的无线传感器网络建设,提供一定的参考.     

A highly sensitive and fast-responding sensor based on electrospun In2O3 nanofibers

In₂O₃ nanofibers with diameters of around 60 nm have been fabricated by electrospinning with a solution containing both poly (vinyl pyrrolidone) (PVP) and indium nitrate, followed by calcination in air at 700 °C. Without further adding catalysts or doping other metal oxides, the sensor based on the as-prepared indium oxide (In₂O₃) nanofibers showed high response and selectivity, fast response and recovery time towards ethanol gas. The simple preparation and excellent properties significantly advance the viability of electrospun gas sensors.     

基于聚合度的无线传感器网络自维护分簇算法

针对无线传感器网络最大连通度生成簇算法建立的簇之间存在重叠度较高的现象,且没有考虑网络能量均衡对网络寿命会产生不良影响的问题,提出了基于聚合度的自维护分簇算法.算法综合节点的聚合度和节点能量选取簇头,并通过簇头节点的迁移来降低网络簇结构的重叠性,同时综合聚合度、能量和相似度选取替补簇头,实现网络的自维护.算法达到降低簇之间的重叠度,均衡网络能量,延长网络寿命的目的.仿真结果验证了算法的有效性.     

基于模糊神经网络的智能巨磁电阻传感器设计

在清华大学微纳器件和系统实验室制备了一种高性能的巨磁电阻(GMR)自旋阀.因为该GMR磁传感器的输出呈高度非线性,不利于后端客户的应用,所以设计了一种用于线性校正用途的模糊神经网络(FNN),并以此构建了智能GMR磁传感器系统,通过Matlab仿真试验验证了该方法的有效性.最后,讨论了单芯片系统(SOC)实现该智能GMR磁传感器的可行性,为进一步的系统集成提供了理论基础.     

基于无线传感器网络的远距离结构健康监测

针对复合材料结构健康监测的特点和需求,实现了一套基于无线传感器网络(WSNs)的远距离结构健康监测系统。系统构成包括前端传感监测子系统、WSNs子系统和远终端监控子系统。为了扩大系统的监测范围,降低系统网络功耗及成本,提高系统的稳定性、智能性和抗毁性,研究了自制的无线传感节点、多跳路由技术及小型化配接电路,改进了终端程序和网络节点程序。实验证明:相对于传统有线的监测方式,基于WSNs的结构健康监测具有灵活性高、负重轻、成本低、搭建移动方便、维护容易等优点。     

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.     

基于Zig Bee协议的温度湿度无线传感器网络

阐述了一种温度湿度智能数据采集的无线传感器网络,介绍了传感器节点的软件与硬件设计.该系统基于Zig Bee无线通信协议设计,克服了有线传感器网络的局限性,避免了其他无线通信技术的高功耗的缺点,节点成本低、网络容量大、生存周期长.实验结果表明:温度测量精度为1℃,湿度精度为3%RH,可以广泛用于环境检测.     

基于网络传感器的大坝安全监测系统

网络传感器是传感器领域发展的一项新兴技术。它在统一网络协议的基础上实现了传感器信号的数字化、网络化变送。为解决传统安全监测系统的弊端,介绍了一种利用微处理器ADμC812和RS-485接口芯片SN65LBC184设计的网络传感器的原理及实现,并利用网络传感器构成网络化大坝监测系统。结果表明:该网络传感器具有通用性好、灵活性强、可靠性高等优点,代表了大坝安全监测系统的新的发展方向。