Wireless Acoustic Emission Sensor Network for Structural Monitoring

The paper presents a prototype wireless system for the detection of active fatigue cracks in aging railways bridges in real-time. The system is based on a small low-cost sensor node, called an AEPod, that has four acoustic emission (AE) channels and a strain channel for sensing, as well as the capability to communicate in a wireless fashion with other nodes and a base station. AEPods are placed at fracture-critical bridge locations. The strain sensor detects oncoming traffic and triggers the AEPod out of its hibernation mode. As the train stresses the fracture-critical member, acoustic emission and strain data are acquired. The data are compressed and filtered at the AEPod and transmitted off the bridge using cell-phone communication.     

A Reliable and High-Bandwidth Multihop Wireless Sensor Network for Mine Tunnel Monitoring

Wireless sensor network (WSN) is considered here for remote monitoring of mine tunnels. Since mine transport and exploiting plane monitoring are the complex tasks that require video monitoring, a major challenge of remote mine tunnel monitoring is the multipath and diffraction effect due to unreliable channel and limited capacity. We propose here a braided cooperative reliable transport (BCRT) algorithm for reliable video transmission within mine tunnel. BCRT maintains one-hop reliability to ensure end-to-end reliability so that it is robust to path breaks. In addition, the BCRT-based WSN uses three consecutive forward neighbors to adjust the data rate to improve the sensing reliability. The proposed WSN is implemented in a real-life mine tunnel. And it is demonstrated to be able to enhance the reliability of the end-to-end monitoring of mine tunnels.     

A Novel RFID-Based Strain Sensor for Wireless Structural Health Monitoring

Conventional tools for deformation measurement are widely used for structural health monitoring—i.e. strain gauges and fiber optic sensors—due to their relative low cost and efficiency. However, these techniques still present some drawbacks particularly in limited access locations, since their usage requires some sort of cabling or battery-driven electronics. Thus, in a few situations there may be room for new technologies for deformation monitoring of structures. One of the options are passive radio frequency identification (RFID)-based sensors. In synthesis, like conventional methods, these sensors are attached to the surface a test-piece, but are then remotely interrogated and powered by a transmitter. The solidarity of the sensor to the underlying material means that the detected signal is modified in a way that can be correlated to sample strain in a given direction. This paper encompasses the project of a wireless deformation sensor based on an inverted-F antenna focusing on its miniaturization and performance optimization. For this purpose, such an antenna was designed with the help of finite element modelling tools for operation on a 2.0 mm-thick aluminium sheet, and then experimentally validated through static loading tests. Finally, even though sensors of this kind are still in early developments, results show that RFID sensors represents a promising method for remote deformation assessment in components.     

Hybrid Micropower Source for Wireless Sensor Network

Wireless sensor networks have become a very significant enabling technology in many applications and the use of environmental energy is a feasible source for low-power wireless sensor networks. The challenges of developing a power supply including generation or conversion, storage, and power management are manifold to extend the lifetime of a wireless sensor network. The objective of this research is to develop an intelligent hybrid power system to realize a self-sustaining wireless sensor node. The photovoltaic and thermoelectric generators are adopted as energy converters. The lithium ion battery and ultracapacitor are used as reservoirs. An intelligent power management system has been developed to control the power distribution. The design data and experimental results show that the hybrid micropower source can extend the lifetime of a sensor network.     

Monitoring in Industrial Systems Using Wireless Sensor Network With Dynamic Power Management

The advances in wireless communication, microelectronics, digital electronics, and highly integrated electronics and the increasing need for more efficient controlled electric systems make the development of monitoring and supervisory control tools the object of study of many researchers. This paper proposes a digital system for energy usage evaluation, condition monitoring, diagnosis, and supervisory control for electric systems applying wireless sensor networks (WSNs) with dynamic power management (DPM). The system is based on two hardware topologies responsible for signal acquisition, processing, and transmission: intelligent sensor modules (ISMs) and remote data acquisition units (RDAUs). The gateway function of the wired network is carried out by remote servers (RSs) based on the Soekris architecture, which is responsible for receiving the data collected and transmitting it to the supervisory controller (SC). To extend the WSN lifetime, sensor nodes implement a DPM protocol. The basic characteristics of the presented system are the following: 1) easy implementation; 2) low-cost implementation; 3) easy implementation of redundant routines (security); 4) portability/versatility; and 5) extended network lifetime.      

智能建筑中无线传感器网络安全分析

无线传感器网络技术是当前非常流行的一种网络技术。论文介绍了无线传感器网络在智能建筑中应用的安全问题,以及在建筑物中确保无线传感器网络安全,提高无线传感器网络性能,最终实现建筑物内设备的智能化管理。     

A Mobile Host Approach for Wireless Powering and Interrogation of Structural Health Monitoring Sensor Networks

Wireless sensor networks (WSNs) for structural health monitoring (SHM) applications can provide the data collection necessary for rapid structural assessment after an event such as a natural disaster puts the reliability of civil infrastructure in question. Technical challenges affecting deployment of such a network include ensuring power is maintained at the sensor nodes, reducing installation and maintenance costs, and automating the collection and analysis of data provided by a wireless sensor network. In this work, a new "mobile host" WSN paradigm is presented. This architecture utilizes nodes that are deployed without resident power. The associated sensors operate on a mechanical memory principle. A mobile host, such as a robot or unmanned aerial vehicle, is used on an as-needed basis to charge the node by wireless power delivery and subsequently retrieve the data by wireless interrogation. The mobile host may be guided in turn to any deployed node that requires interrogation. The contribution of this work is the first field demonstration of a mobile host wireless sensor network. The sensor node, referred to as THINNER, capable of collecting data wirelessly in the absence of electrical power was developed. A peak displacement sensor capable of interfacing with the THINNER sensor node was also designed and tested. A wireless energy delivery package capable of being carried by an airborne mobile host was developed. Finally, the system engineering required to implement the overall sensor network was carried out. The field demonstration took place on an out-of-service, full-scale bridge near Truth-or-Consequences, NM.     

A Wearable and Wireless Sensor System for Real-Time Monitoring of Toxic Environmental Volatile Organic Compounds

An integrated volatile organic toxicants sensor with a Bluetooth device interface has been developed. The device is based on novel tuning fork sensor platform along with a wireless communication/interface technology taken in an integrated system approach. It features high sensitivity and selectivity. The sensitivity and selectivity are accomplished through the use of novel tuning fork sensor modified by design (molecularly imprinted) polymers and selective filtering. Experiments have shown that the device can detect toxic volatile organic compounds (VOCs) under high concentrations of common interferents from flavors and fragrances. Applications of the device for detection of BTEX in real-world situations such as outdoor and gas station VOCs have also been demonstrated. All these features make the device a promising candidate to be deployed in real-world applications, particularly in environmental health and air pollution studies.      

A Wireless, Passive Embedded Sensor for Real-Time Monitoring of Water Content in Civil Engineering Materials

A wireless, passive embedded sensor was applied for real-time monitoring of water content in civil engineering materials such as sands, subgrade soils, and concrete materials. The sensor, which comprised of a planar inductor-capacitor (LC) circuit, was embedded in test samples so that the internal water content of the samples could be remotely measured with a loop antenna by tracking the changes in the sensor's resonant frequency. Since the dielectric constant of water was much higher compared with that of the test samples, the presence of water in the samples increased the capacitance of the LC circuit (capacitance of the capacitor was proportional to the dielectric constant of the medium between its electrodes), thus decreasing the sensor's resonant frequency. Using the described sensor, a study was conducted to investigate the drying rate of sand samples of different grain sizes. A study was also conducted to measure the curing rate of a portland cement concrete slab during casting, and its drying rate after it has been soaked in water. The described sensor technology can be applied for long-term monitoring of localized water content inside soils and sands to understand the environmental health in these media. In addition, this sensor will be useful for monitoring water content within concrete supports and road pavements. The measurement of water content is important for civil engineering infrastructure since excess water may hasten their degradation.      

A New Wireless Sensor System for Smart Diapers

This letter presents a new wireless sensor system for smart diaper application, which consists of an interrogator circuit, an antenna, and a passive LC resonating sensor tag. The wireless link between the interrogator circuit and the sensor tag is established through the inductive coupling. The wetting of the diaper shifts the resonating frequency of the sensor tag, changing the inductive link, and thus trigger an ldquoonrdquo or ldquooffrdquo condition reflected at the interrogator circuit. With suitable sensor tags, smart diapers can be achieved in a straightforward and low cost approach.     

Wireless Industrial Monitoring and Control Using a Smart Sensor Platform

A wireless smart sensor platform (based on patent pending technologies, Ramamurthy ) targeted for instrumentation and predictive maintenance systems is presented. The generic smart sensor platform with "plug-and-play" capability supports hardware interface, payload and communications needs of multiple inertial and position sensors, and actuators, using a RF link (Wi-Fi, Bluetooth, or RFID) for communications, in a point-to-point topology. The design also provides means to update operating and monitoring parameters as well as sensor/RF link specific firmware modules "over-the-air." Sample implementations for industrial applications and system performance are discussed     

一种无线传感器网络被动定位方法设计与实现

从无线传感器网络节点自定位出发,分析比较了无线传感器自定位的几种常见定位算法,并给出现有算法存在的问题;在嵌入GPS模块的无线传感器网络汇聚节点上提出一种新的被动定位方法,并在软硬件上得到了实现．与传统的定位方法比较,它避免了无线传感器网络必须在每个节点嵌入GPS模块的同时,能在不增加体积、成本、通信功耗的情况下提供精确的定位位置．     

A Ring-Shaped Photodiode Designed for Use in a Reflectance Pulse Oximetry Sensor in Wireless Health Monitoring Applications

We report a photodiode for use in a reflectance pulse oximeter for use in autonomous and low-power homecare applications. The novelty of the reflectance pulse oximeter is a large ring shaped backside silicon pn photodiode. The ring-shaped photodiode gives optimal gathering of light and thereby enable very low light-emitting diode (LED) driving currents for the pulse oximeter. The photodiode also have a two layer SiO₂/SiN interference filter yielding 98% transmission at the measuring wavelengths, 660 nm and 940 nm, and suppressing other wavelengths down to 50% transmission. The photodiode has a radius of 3.68 mm and a width of 0.78 mm giving an area of 18 mm². The capacitance of the photodiode is measured to 34.5 nF. The quantum efficiency of the photodiode is measured to 55% and 62% at 660 nm and 940 nm, respectively. It is acceptable for this prototype but can be improved. The sensor also has an on-chip integrated Au thermistor for measuring the skin temperature of the body. The thermistor has a Temperature Coefficient of Resistance of 2.7·10^-3 K^-1 and a repeatability on temperature measurements of ±0.26°C. The photodiode is fabricated in a clean room environment by two diffusion processes and an Advanced Silicon Etch to make the hole in the middle for the LEDs. The sensor is designed to be integrated in a sticking patch of hydrocolloid polymer together with integrated electronics, radio communication unit, and a coin cell battery. The reflectance pulse oximetry sensor is demonstrated to work in a laboratory setup with a Ledtronics dual LED with wavelengths of 660 and 940 nm. Using this setup photoplethysmograms which clearly show the cardiovascular cycle have been recorded. The sensor is shown to work very well with low currents of less than 10 mA.     

Highway Bridge Assessment Using an Adaptive Real-Time Wireless Sensor Network

A real-time wireless sensor network platform capable of maintaining lossless data transmission over several minutes of continuous, high-rate sampling is presented in this paper. The platform was designed specifically to provide the capability to enable expeditious system identification, as well as load rating of highway bridges without compromising the typical data acquisition parameters employed in comparable cable-based tests. Consequently, the hardware signal conditioning interface permits data collection from a variety of sensors typical to structural health monitoring, including accelerometers, strain transducers, and temperature sensors. The embedded software features a proprietary network transmission protocol capable of lossless, real-time delivery of up to 40 measurement channels at an effective sampling rate of 128 samples per second per channel. Documented in this paper is a field study on an end-of-service highway bridge in which ambient vibration monitoring was performed using 60 accelerometers interfaced with 30 wireless sensor nodes operating within one of two simultaneously operating star topology networks. In addition, an experimental load rating of the entire structure was performed through large-scale strain measurement facilitated by the same wireless sensor network platform.     

A Motion-Tracking Ultrasonic Sensor Array for Behavioral Monitoring

The application of Kalman filtering to track subjects' movements during a behavioral experiment is discussed. Specifically, an overhead array of wireless, ultrasound sensors automatically tracks the position of a parent, child, and stranger over a 4.45 m × 4.23 m observation area. This WiPsy (Wireless sensors for Psychology research) system provides accurate, real-time quantitative metrics for psychological evaluation in lieu of traditional qualitative manual coding. Moreover, tracking subjects using ultrasound sensors is less error-prone than existing methods that track based on human coding of video. In particular, the Kalman filter, which forms the core of this tracking system, can locate targets with a mean square error of about 1.3 m(2). Overall, WiPsy strives to streamline data acquisition, processing, and analysis by providing previously unavailable assessment parameters.     

A Magnetically Controlled Wireless Optical Oxygen Sensor for Intraocular Measurements

The influence of oxygen on various ophthalmological complications is not completely understood and intraocular oxygen measurements are essential for better diagnosis and treatment. A magnetically controlled wireless sensor device is proposed for minimally invasive intraocular oxygen concentration measurements. This device will make it possible to make measurements at locations that are currently too invasive for human intervention by integrating a luminescence optical sensor and a magnetic steering system. The sensor works based on quenching of luminescence in the presence of oxygen. A novel iridium phosphorescent complex is designed and synthesized for this system. A frequency-domain lifetime measurement approach is employed because of the intrinsic nature of the lifetime of luminescence. Experimental results of the oxygen sensor together with magnetic and hydrodynamic characterization of the sensor platform are presented to demonstrate the concept. In order to use this sensor for in vivo intraocular applications, the size of the sensor must be reduced, which will require an improved signal-to-noise ratio.     

应用于无线传感器节点的微小型复合能源收集系统(英文)

设计并实现了一种可应用于无线传感器节点的复合能源系统样机,基于一种无线地磁交通流传感器,提出了本文的设计目标.选择太阳能、风能、应变能作为系统的能量源.根据这3种不同能量源的特性,对能量管理模块与能量储存模块进行了针对性设计,最后实现并测试了样机.实验结果表明,该样机可连续35 h在3.55 V电压下输出50mW的电能.     

WSN中基于梯度有网关分簇拓扑控制研究

针对ETBG算法在选取簇头时权值单一,未考虑距离在数据传输的影响,造成一些簇内距离较远节点传输耗能过大,影响到整个网络的生命周期。本文在节点选择簇头的过程中考虑了能量和距离的均衡因素,采用综合权值大的节点作为簇头节点,利用在簇头间选择网关利用梯度建立簇树,能解决ETBG算法在簇头距离过远情况下直接通信耗能过高的弊端,同时能减少网内簇头的数目,通过簇头轮换策略,可以延长网络的生命周期。     

基于无线传感网络PCR仪温度校准装置的研制

本文介绍了一种无线传感网络PCR仪温度校准装置的研制,主要包括无线温度传感器及无线手持接受处理装置的设计.采用标准铂电阻温度计与电测设备连接构成高精度测温系统对校准装置性能进行测试,测试结果符合JJF 1821-2020《聚合酶链反应分析仪温度校准装置校准规范》要求.