一种无线振动传感器频响带宽提高方法

高频响无线振动传感器是机械设备预测性维护领域不可或缺的信号采集设备,目前机械设备监测应用中常用的无线振动传感器频率响应较低,限制了其在机械设备预测性维护领域的应用;为了进一步提高无线振动传感器频率响应带宽,提出一种提高无线振动传感器频响范围的方法,从结构设计、振动探头设计、信号调理链路设计和模数转换器设计4个方面对传统无线振动传感器进行了改进;实验结果表明,无线振动传感器带宽提高方法将无线振动传感器频率响应带宽提高了7.96 dB;在振动监测领域具有较强的实用性,对智能传感器制造领域具有较好的指导意义.     

一种无线传感器监测系统的设计和研究

给出了一种无线传感器监测系统的设计与开发,结合MEMS微传感器和无线通信技术,研究了MEMS微加速度计检测信号的测量与无线传输技术,设计了系统电路,并完成了原型装置的制作与调试。通过无线、有线传感器的时频响应特性比较表明,无线传感器监测系统能够满足桥梁健康监测的要求。     

基于ZigBee的便携式矿用多参数传感器设计

基于ZigBee无线通信技术,结合现有的煤矿传感器,设计了一款便携式矿用安全监测传感器。该传感器具有自组网、小体积、高效率、低功耗、低成本的特点,集信号采集、液晶显示和组网通信功能于一体。该传感器集成监测瓦斯浓度、温度、电流、压力等多种环境参数,有效弥补了矿用单参数传感器功能单一的不足;以无线通信代替有线通信,可固定安装或由工作人员随身携带,覆盖更多的监测盲点,更有利于系统的扩展和维护。     

Diagnostic techniques for the dynamics of a thin liquid film under forced flow and evaporating conditions

Motivated by quantification of micro-hydrodynamics of a thin liquid film which is present in industrial processes, such as spray cooling, heating (e.g., boiling with the macrolayer and the microlayer), coating, cleaning, and lubrication, we use micro-conductive probes and confocal optical sensors to measure the thickness and dynamic characteristics of a liquid film on a silicon wafer surface with or without heating. The simultaneous measurement on the same liquid film shows that the two techniques are in a good agreement with respect to accuracy, but the optical sensors have a much higher acquisition rate up to 30 kHz which is more suitable for rapid process. The optical sensors are therefore used to measure the instantaneous film thickness in an isothermal flow over a silicon wafer, obtaining the film thickness profile and the interfacial wave. The dynamic thickness of an evaporating film on a horizontal silicon wafer surface is also recorded by the optical sensor for the first time. The results indicate that the critical thickness initiating film instability on the silicon wafer is around 84 μm at heat flux of ~56 kW/m². In general, the tests performed show that the confocal optical sensor is capable of measuring liquid film dynamics at various conditions, while the micro-conductive probe can be used to calibrate the optical sensor by simultaneous measurement of a film under quasi-steady state. The micro-experimental methods provide the solid platform for further investigation of the liquid film dynamics affected by physicochemical properties of the liquid and surfaces as well as thermal-hydraulic conditions.     

无线传感器网络在土木工程应用中的试验研究

传感器作为结构健康监测的基本组成部分,一直是人们关注的热点。该文论述了传感器技术的发展,尤其是无线传感器及无线传感器网络技术。介绍了由UCBerkeley研发的无线传感器节点-MICA的软硬件系统,针对结构健康监测,在实验室中建立和开发了一个原型监测系统,将选用的无线传感器节点布置在实验室两层结构模型上,组成一个无线传感器网络。通过小振动台试验证明无线传感器是完全可以应用于将来实际结构监测系统中的。     

Decentralized fault detection and isolation in wireless structural health monitoring systems using analytical redundancy

One of the most critical issues when deploying wireless sensor networks for long-term structural health monitoring (SHM) is the correct and reliable operation of sensors. Sensor faults may reduce the quality of monitoring and, if remaining undetected, might cause significant economic loss due to inaccurate or missing sensor data required for structural assessment and life-cycle management of the monitored structure. This paper presents a fully decentralized approach towards autonomous sensor fault detection and isolation in wireless SHM systems. Instead of physically installing multiple redundant sensors in the monitored structure (“physical redundancy”), which would involve substantial penalties in cost and maintainability, the information inherent in the SHM system is used for fault detection and isolation (“analytical redundancy”). Unlike traditional centralized approaches, the analytical redundancy approach is implemented distributively: Partial models of the wireless SHM system, implemented in terms of artificial neural networks in an object-oriented fashion, are embedded into the wireless sensor nodes deployed for monitoring. In this paper, the design and the prototype implementation of a wireless SHM system capable of autonomously detecting and isolating various types of sensor faults are shown. In laboratory experiments, the prototype SHM system is validated by injecting faults into the wireless sensor nodes while being deployed on a test structure. The paper concludes with a discussion of the results and an outlook on possible future research directions.     

Autonomous wireless radar sensor mote for target material classification

Autonomous wireless sensor networks consisting of different types of sensor modalities have been receiving greater attention from researchers due to their versatility and portability. These autonomous sensor networks commonly include passive sensors such as infrared, acoustic, vibration, and magnetic nodes. However, fusion of active sensors in the integrated sensor network, such as Doppler radars, may offer powerful capabilities for many different sensing and classification tasks. In this work, we demonstrate the design and implementation of an autonomous wireless sensor network integrating a Doppler sensor with commercial off-the-shelf components. We investigate the effect of various types of target materials on the measured radar signal as one of the applications of the newly designed radar–mote network. Different types of materials affect the amount of energy reflected back to the source of an electromagnetic wave. We obtain mathematical and simulation models for the reflectivity of different homogeneous non-conducting materials and study the effect of such reflectivity on the classification of targets. We validate our simulation results using real experimental data collected through our autonomous radar–mote sensor network using various types of targets.     

被动式煤矿井下环境安全监测系统设计

介绍了一种基于ZigBee无线网络及传感器检测技术的新型被动式煤矿井下环境安全监测系统设计方案。该系统将带有传感器的移动检测终端设备置于矿工帽子上,通过无线传感网络,实现被动式的环境监测及无线信息传输,大大增加了监测的灵活性,并解决了监测死角的问题。     

Investigation on formaldehyde gas sensor with ZnO thick film prepared through microwave heating method

ZnO nanopowders were prepared through microwave heating method. ZnO thick film sensors were fabricated by using ZnO nanopowders as sensing materials. The phase composition and morphology of the material particles were characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The gas-sensing properties of the sensors based on ZnO nano-materials were investigated. It was found that the sensor based on ZnO nano-materials (low power, 10× 10 min) exhibited very high responses to benzene and toluene when operating at 440 and 370 °C, respectively; but the sensor based on ZnO (low power, 10× 10 min) showed very low responses to benzene and toluene when operating at 205–215 °C. The sensor based on ZnO (low power, 10× 10 min) showed high response and good selectivity to dilute formaldehyde when operating at 210 °C; especially, the response to 0.001 ppm HCHO attained 7.4 when operating at 210 °C.     

Remote monitoring system with wireless sensors module for room environment

A wireless sensor module with several air quality monitoring sensors was developed for indoor environment monitoring system in home networking. The module has various enlargements for various kinds of sensors such as humidity sensor, temperature sensor, CO₂ sensor, flying dust sensor, etc. The developed wireless module is very convenient to be installed on the wall of a room or office, and the sensors in the module can be easily replaced due to well-designed module structure and RF connection method. To reduce the system cost, only one RF transmission block was used for sensors’ signal transmission to 8051 microcontroller board in time-sharing method. In this home networking system, various indoor environmental parameters could be monitored in real time from RF wireless sensor module. Indoor vision was transferred to client PC or Personal Digital Assistant (PDA) from surveillance camera installed indoor or desired site. Web server using Oracle DB was used for saving the visions from web-camera and various data from wireless sensor module.     

基于无线传感网络的环境监控系统

为了实现对环境系统的动态远程监控,设计了一种基于Zigbee的无线传感网络监控系统.Zigbee无线数传终端模块通过内置的单片机系统,实现了不同传感器的接口协议,并对传感器数据进行了实时读取、编码与发送;系统中的协调器实现对数据包的接收、解码、验证并将正确的数据转发数据至服务器;无线传感网络中引入了ZStack协议,从而实现了对无线终端与协调器节点的动态增删;监控终端分为桌面与移动端,通过无线网络访问服务器中存储的数据,实现对环境系统的远程实时监控.     

超声波检测的AE传感器设计与实现

针对目前国内用于结构健康监测的无线传感器频带不够宽,不能检测声波信号的现状,提出了一种可以检测声波信号的新型无线压电传感器的设计和制作方法;研究了ZigBee协议栈内容,设计和实现了体积小、功耗低的无线传感器节点和基站的硬件和软件程序部分,并对制成的传感器进行初步测试;试验表明它有较好的精度,频带更宽,可以用于较高频段的结构健康监测,具有广阔的应用前景。     

基于蓝牙传感器网络技术的桥梁健康监测系统

传感器之间的通信一直受到有线连接和各种无线通信协议的限制。运用一种随处可见并成本低廉的无线通信技术建立传感器区域网络(SANs)将加速传感器技术的进一步发展。自身有着很多优点的蓝牙作为一种世界广泛认可的标准,对于SANs是可行的选择。围绕蓝牙技术提出了一种方法构建由固定无线传感器组成的传感器网络,用于桥梁的健康监测;提出了拓扑组成方案,并对不同传感器信息的传递以及链接能量的问题进行了探讨。     

磁弹性无线微生物传感器研究进展

磁弹性无线传感是一门新兴的传感技术,磁弹性无线传感器基于磁致伸缩原理而设计,传感器中信号的激励与传送通过磁场进行,传感器与检测仪器之间没有任何物理连接,属于无线无源传感器.主要介绍了磁弹性无线微生物传感器的工作原理、分类及其应用.通过将传感器置于密闭容器中,在线监测微生物的新陈代谢过程,以及进行抗生素等药物的药效在线评...     

重金属监测的光学单元无线化系统设计与研究

基于无线传感器网络技术,结合光学测量高精度的特性,设计了一套用于重金属监测的无线化系统.首先,完成了无线采集节点的整体架构设计;其次,在分析光学传感单元的特性及机理基础上,采用模块化设计方法,进行了光学无线采集节点的各个单元硬件设计和相应的软件设计;最后,对无线系统进行了功能验证实验.实验表明,所设计的光学无线化系统具有精度高、低成本、低功耗、布设便捷等优点,在重金属监测等相关领域具有很好的应用前景和实用价值.     

基于无线传感器网络的煤矿顶板压力监测系统

设计了煤矿顶板压力监测系统,采用无线传感网络的节点作为顶板压力数据采集的终端,采集顶板的压力变化数据。各节点采用基于IEEE802.15.4和ZigBee协议栈的无线方式将数据传送到汇聚节点,汇聚节点采用有线通信方式将采集到的数据通过USB传输接口传输至地面的管理监控站,实现对矿井顶板压力数据的实时监控。     

基于无线传感器网络的煤矿瓦斯监测系统的设计

为了满足煤矿瓦斯监测的需要,开发了一种基于无线传感器网络的智能化瓦斯监测系统。该系统采用数字瓦斯传感器实时检测瓦斯,避免了普通传感器需进行A/D转换的复杂性,提高了测量精度;采用无线传感器网络,克服了有线传感器网络的局限性,避免了其它无线通信技术高功耗的缺点。文章详细介绍了系统的硬件和软件设计,并给出了测试结果。     

无线传感器网络煤矿顶板压力在线监测系统

近年来我国煤矿安全事故时有发生,安全形势十分严竣;在采矿生产过程中最常发生的就是冒顶事故;通过实时监测顶板压力的变化,可以研究矿井顶板压力的规律,从而采取预防措施,有效地防止事故的发生;本系统采用无线传感网络的节点作为顶板压力致据采集的终端,采集顶板的压力变化数据;各节点采用基于TEEE802.15.4和ZigBeeTM协议栈的无线方式将数据传送到汇聚节点,汇聚节点采用有线通信方式将采集到的数据通过USB传输接口传输至地面的管理监控站,实现对矿井顶板压力数据的实时监控;当顶板压力数据接近或达到报警压力值,节点和汇聚节点发出卢光报警信息,同时地面监测站发出压力橙色或红色报警信息,促使安全部门采取有效措施,防止事故的发生,达到安全生产的目的.     

Hydrogen sensors with double dipole layers using a Pd-mixture-Pd triple-layer sensing structure

This paper reports on new GaN sensors using a Pd-mixture-Pd triple-layer sensing structure to enhance their sensitivity to hydrogen at the tens of ppm level. The proposed hydrogen sensor biased with a constant voltage produced relatively high sensing responses of 4.84 × 10⁵% at 10,100 ppm and 8.7 × 10⁴% at 49.1 ppm H₂ in N₂. The corresponding barrier height variations are calculated to be 220 and 168 mV. When the sensor is biased by a constant current with maximum power consumption of 0.4 mW, a sensing voltage as an output signal showed a voltage shift of more than 17 V (the highest value ever reported) at 49.1 ppm H₂ in N₂. By comparison to Pd-deposited GaN sensors, the improvement in static-state performance is likely attributed to double dipole layers formed individually at the Pd–GaN interface and inside the mixture. Moreover, voltage transient response and current transient response to various hydrogen-containing gases were experimentally studied. The new finding is that the former response time is shorter than the latter one.     

Motion fault detection and isolation in Body Sensor Networks

Significant amount of research and development is being directed on monitoring activities of daily living of senior citizens who live alone as well as those who have certain motion disorders such as Alzheimer’s and Parkinson’s. A combination of sophisticated inertial sensing, wireless communication and signal processing technologies has made such a pervasive and remote monitoring possible. Due to the nature of the sensing and communication mechanisms, these monitoring sensors are susceptible to errors and failures. In this paper, we address the issue of identifying and isolating faulty sensors in a Body Sensor Network that is used for remote monitoring of daily living activities. We identify three different types of faults in a Body Sensor Network and propose fault isolation strategies using history-based and non-history based approaches. The contributions of this paper are: (i) faulty sensor node identification in a small number of deployed body sensors (accelerometers); and (ii) identification of a faulty sensor node using a statically or dynamically bound group of sensor nodes that is sharing similar sensor signal patterns.