Non-destructive Evaluation of Composite Pressure Vessel by Using FBG Sensors

In recent years, advanced composite structures are used extensively in many industries such as aerospace, aircraft, automobile, pipeline and civil engineering. Reliability and safety are crucial requirements posed by them to the advanced composite structures be- cause of their harsh working conditions. Therefore, as a very important measure, structural health monitoring （SHM） in-service is deft- nitely demanded for ensuring their safe working in-situ. In this paper, fiber Bragg grating （FBG） sensors are surface-mounted on the hoop and in the axial directions of a FRP pressure vessel to monitor the strain status during its pressurization. The experimental results show that the FBG sensors could be used to monitor the strain development and determine the ultimate failure strain of the composite pressure vessel.

A CuNi/C Nanosheet Array Based on a Metal–Organic Framework Derivate as a Supersensitive Non-Enzymatic Glucose Sensor

Bimetal catalysts are good alternatives for nonenzymatic glucose sensors owing to their low cost, high activity, good conductivity, and ease of fabrication. In the present study, a self-supported CuNi/C electrode prepared by electrodepositing Cu nanoparticles on a Ni-based metal–organic framework(MOF) derivate was used as a non-enzymatic glucose sensor. The porous construction and carbon scaffold inherited from the Ni-MOF guarantee good kinetics of the electrode process in electrochemical glucose detection. Furthermore, Cu nanoparticles disturb the array structure of MOF derived films and evidently enhance their electrochemical performances in glucose detection. Electrochemical measurements indicate that the CuNi/C electrode possesses a high sensitivity of17.12 mA mM^(-1) cm^(-2), a low detection limit of 66.67 nM,and a wider linearity range from 0.20 to 2.72 mM. Additionally, the electrode exhibits good reusability, reproducibility, and stability, thereby catering to the practical use of glucose sensors. Similar values of glucose concentrations in human blood serum samples are detected with our electrode and with the method involving glucose-6-phosphate dehydrogenase; the results further demonstrate the practical feasibility of our electrode.

A novel sensitive non-enzymatic glucose sensor

Cu nanoclusters were electrochemically deposited on the film of a Nafion-solubilized multi-wall carbon nanotubes (CNTs) modified glassy carbon electrode (CNTs-GCE), which fabricated a Cu-CNTs composite sensor (Cu-CNTs-GCE) to detect glucose with non-enzyme. The linear range is 7.0 × 10?7 to 3.5 × 10?3 mol/L with a high sensitivity of 17.76 μA/(mmol L), with a low detection limit 2.1 × 10?7 mol/L, fast response time (within 5 s), good reproducibility and stability.

A Novel Uniplanar Multi-Electrode Capacitive Sensor for In-Situ Weathering Damage Detection of Nonmetallic Materials

A uniplanar capacitive sensor with 5-electrodes on one plane substrate and a large reflector electrode,was designed to get the corresponding capacitance information for weathering damage detection of non-metallic materials exposed to a service environment.A 2-D finite-element method was employed to simulate the electric potential distribution and capacitance measurements for the sensor.2 marble slabs,one was healthy and the other was notched,were experimentally detected.Both the simulation and the preliminary experimental results show that the measured capacitances decrease after weathering damage occurs in nonmetallic material.The reflector can enlarge the sensitive depth.The weathering assessment of nonmetallic materials can be done by processing the measured capacitances.The proposed approach can effectively detect the weathering damage of nonmetallic material and can be practically used for in-situ weathering damage evaluation.

RELOCATION ALGORITHM FOR NON-UNIFORM DISTRIBUTION IN MOBILE SENSOR NETWORK

Energy is the determinant factor for the survival of Mobile Sensor Networks(MSN).Based on the analysis of the energy distribution in this paper,a two-phase relocation algorithm is proposed based on the balance between the energy provision and energy consumption distribution.Our main objectives are to maximize the coverage percentage and to minimize the total distance of node movements.This algorithm is designed to meet the requirement of non-uniform distribution network applications,to extend the lifetime of MSN and to simplify the design of the routing protocol.In ad-dition,test results show the feasibility of our proposed relocation algorithm.

Research on Non-Contact Weak Current Detection Technology

With the continuous development of industrial technology, the weak current plays an increasingly important role in all fields of life. In order to facilitate the user to carry, the study of contactless weak current measurement technology is also emerging. This article’s design idea is based on two-dimensional reluctance sensor device built non-contact weak current detection system. The system uses the reluctance sensor HMC1002 to collect the current signal and the temperature sensor DS18B20 to compensate the temperature. The signals collected by the reluctance sensor and the temperature sensor are extremely weak. After being amplified by the amplifying circuit, the signal is conducive to subsequent detection and processing. Filter circuit can filter out interference signals to achieve the goal of improving accuracy. After the corresponding algorithm of the microcontroller will convert the signal voltage, easy to read and store, thus designing a non-contact current measurement capable of detecting weak currents and achieving higher accuracy.

Piezoelectric Actuator/Sensor Wave Propagation Based Nondestructive Active Monitoring Method of Concrete Structures

In order to monitor the basic mechanical properties and interior damage of concrete structures,the piezoelectric actuator/sensor based wave propagation method was investigated experimentally in the laboratory using a specifically designed test setup.The energy attenuation of stress waves was measured by the relative index between the output voltage of sensors and the excitation voltage at the actuator.Based on the experimental results of concrete cube and cylinder specimens,the effect of excitation frequencies,excitation amplitude,wave propagation paths and the curing age on the output signals of sensors are evaluated.The results show that the relative voltage attenuation coefficient RVAC is an effective indicator for measuring the attenuation of stress waves through the interior of concrete.

Performance and Challenges in Utilizing Non-Intrusive Sensors for Traffic Data Collection

Extensive field tests of non-intrusive sensors for traffic volume, speed and classification detection were conducted under a variety of traffic composition and road width conditions. The accuracy challenges of utilizing non-intrusive sensors for traffic data collection were studied. Both fixed and portable sensors with infrared, microwave and image recognition technologies were tested. Most sensors obtained accurate or fairly accurate measurements of volume and speed, but vehicle classification counts were problematic even when classes were reduced to 3 to 5 compared to FHWA’s 13-class standard scheme.

Detecting the Position of the Moving-iron Solenoid by Non-displacement Sensor Based on Parameter Identification of Flux Linkage Characteristics

Currently, most researches use signals, such as the coil current or voltage of solenoid, to identify parameters; typically, parameter identification method based on variation rate of coil current is applied for position estimation. The problem exists in these researches that the detected signals are prone to interference and difficult to obtain. This paper proposes a new method for detecting the core position by using flux characteristic quantity, which adds a new group of secondary winding to the coil of the ordinary switching electromagnet. On the basis of electromagnetic coupling theory analysis and simulation research of the magnetic field regarding the primary and secondary winding coils, and in accordance with the fact that under PWM control mode varying core position and operating current of windings produce different characteristic of flux increment of the secondary winding. The flux increment of the electromagnet winding can be obtained by conducting time domain integration for the induced voltage signal of the extracted secondary winding, and the core position from the two-dimensional fitting curve of the operating winding current and flux-linkage characteristic quantity of solenoid are calculated. The detecting and testing system of solenoid core position is developed based on the theoretical research. The testing results show that the flux characteristic quantity of switching electromagnet magnetic circuit is able to effectively show the core position and thus to accomplish the non-displacement transducer detection of the said core position of the switching electromagnet. This paper proposes a new method for detecting the core position by using flux characteristic quantity, which provides a new theory and method for switch solenoid to control the proportional valve.

Application Research of the Non-Destructive Testing Using Optical Fiber Sensor

In this paper, an optical fiber sensor is designed by using optical Faraday effect. It is composed of fiber collimator, polarizer, magneto-optical crystal and mirror. Based on the magnetic flux leakage (MFL) theory, The optical fiber sensor was placed between two permanent magnets with the N-pole. Therefore, the optical fiber sensing system was built to detect the defective ferromagnetic objects. Theoretical and experimental studies shown that the system can identify a little defects, such as irons’ blind hole (diameter φ =?3mm , depth t = 4mm?), irons’ grooves (length l= 30mm , width?ω = 10mm ), hole (φ?=?3mm ) and crackle etc. The system has the characteristics of small size, high sensitivity, fast signal response and high resolution. In terms of the defective oil and gas pipelines detection, The optical fiber sensing system is used in non-destructive testing, which will be valuable and meaningful.

Design, Implementation and Simulation of Non-Intrusive Sensor for On-Line Condition Monitoring of MV Electrical Components

Non-intrusive measurement technology is of great interest for the electrical utilities in order to avoid an interruption in the normal operation of the supply network during diagnostics measurements and inspections. Inductively coupled electromagnetic sensing provides a possibility of non-intrusive measurements for online condition monitoring of the electrical components in a Medium Voltage (MV) distribution network. This is accomplished by employing Partial Discharge (PD) activity monitoring, one of the successful methods to assess the working condition of MV components but often requires specialized equipment for carrying out the measurements. In this paper, Rogowski coil sensor is presented as a robust solution for non-intrusive measurements of PD signals. A high frequency prototype of Rogowski coil is designed in the laboratory. Step-by-step approach of constructing the sensor system is presented and performance of its components (coil head, damping component, integrator and data acquisition system) is evaluated using practical and simulated environments. Alternative Transient Program-Electromagnetic Transient Program (ATP-EMTP) is used to analyze the designed model of the Rogowski coil. Real and simulated models of the coil are used to investigate the behavior of Rogowski coil sensor at its different stages of development from a transducer coil to a complete measuring device. Both models are compared to evaluate their accuracy for PD applications. Due to simple design, flexible hardware, and low cost of Rogowski coil, it can be considered as an efficient current measuring device for integrated monitoring applications where a large number of sensors are required to develop an automated online condition monitoring system for a distribution network.

基于线激光的压缩机曲轴圆度和平面度测量

目前人工使用千分表测量空调压缩机曲轴圆度和平面度时存在易伤工件表面、效率低和不能精确评定等问题。针对上述问题,设计了一套基于线激光位移传感器的空调压缩机曲轴圆度和平面度非接触式测量系统。首先,通过测量标准量棒,提出一种系统误差的标定方法;其次,基于线激光采样数据,开发了一种曲轴横截面圆度测点的提取算法,并将系统误差用于测点补偿,实现曲轴圆度测量;接着根据曲轴平面测点间的斜率分离出轮廓线,通过均匀下采样方法获取精简点云数据并采用最小二乘法实现曲轴平面度测量;最后,基于上述方法开展了曲轴圆度和平面度的测量实验。实验结果表明:该测量系统的圆度测量精度<4μm,平面度测量精度<2μm,圆度重复度测量误差<0.8μm,平面度重复度测量误差<0.3μm,满足曲轴圆度和平面度快速准确的测量需求。

基于磁心与线圈参数优化的非侵入式磁场取能系统功率密度提升方法

非侵入式磁场取能系统具有结构简单、供电稳定等优点,是解决变电站母排环境中状态监测传感器电池供电寿命有限的有效手段,但因功率密度较低制约了其应用。对于非侵入式磁场取能系统,磁心与线圈参数对其功率密度的影响非常显著。然而,现有方法对磁心与线圈参数的分析相对独立,优化磁心时仅以互感为指标,忽略了该过程线圈参数变化对功率密度的影响。对此,该文考虑磁心尺寸对线圈参数的影响,以功率密度为指标,详细分析线圈匝数、线圈线径、磁柱侧面边长与叠片厚度对系统功率密度的影响。并在此基础上,提出一种优化磁心与线圈参数的功率密度提升方法,即设计线圈匝数、线圈线径、磁柱侧面边长与叠片厚度的最优值,以获取更高的功率密度。最后,基于所提出的方法制作了系统样机并进行测试。实验结果表明,对于限定磁心尺寸为30 mm×30 mm×40 mm的系统,在100 A母排电流下,系统经磁心与线圈优化后功率密度可达4.18 mW/cm~3,提升至系统优化前功率密度的35倍,验证了所提出方法提升功率密度的有效性。

多传感器融合的火灾监测机器人设计

针对目前火灾报警系统不能应用在城市中非密闭空间的问题,提出一种适用于非密闭空间的多传感器融合的火灾监测机器人。该机器人采用履带式结构适应多地形移动,根据城市内非密闭下空间火势初期主要特征参数确定采集模块的搭建;利用D-S证据理论对多传感器火灾数据进行融合检测,以降低单个传感器的误报率,来提高对非密闭空间火灾事故的精确判定,并对火灾进行现场警报与远程回传。实验表明,与单一传感器判断相比,引入D-S证据理论的火灾监测机器人的火灾检测不确定性下降,检测精度得到了提高。

非接触式生命体征检测装置的设计

为解决临床医学、急救或居家养老等应用场景中无法直接使用传统穿戴式监测仪器实时监测人体生命体征的问题,设计了一种基于多普勒雷达的非接触式生命体征检测装置,该装置通过STM32F429IGT6控制器从多普勒雷达检测的信号中实时提取人体呼吸和心跳信号。其硬件主要由微控制器、多普勒雷达传感器信号放大电路、滤波器、电平抬升电路等部分组成,系统通过IIR带通滤波实现呼吸和心跳信号分离与提取,使用FFT对分离的呼吸和心跳信号进行实时频谱分析,计算并显示呼吸和心跳次数。实验测试结果表明,该装置能有效实时检测人体的呼吸和心跳次数,实现2 m范围内的非接触式人体生命体征检测,心跳次数最大均值误差为9.14%,呼吸次数最大均值误差为4.7%。

非接触式柔性自偏置磁电电流传感器设计与应用

针对电网中现有电流传感器存在的易磁芯饱和、体积大、响应带宽窄、制备成本较高等问题,设计了一种柔性自偏置磁电电流传感器。首先,测试了磁电电流传感器在零偏置状态下的磁电性能,磁电电压系数可达17.65 V/(cm·Oe),表明传感器在零偏置状态下具有优异的磁电响应性能;然后,通过搭建的电流测试平台对传感器电流检测能力进行了验证,结果表明,传感器在谐振及工频频率时都具有良好的电流监测能力,且在工频电流50 Hz时灵敏度为33.07 mV/A,具有优异的灵敏度和线性度;最后,设计的磁电电流传感器在电力电缆护层环流监测业务上进行了试点应用,运行良好,表明非接触式柔性自偏置磁电电流传感器在电网非接触电流检测领域具有很大的应用价值和广阔的应用前景。

用磁阵列传感器去偏心误差的非接触式电流测量方法

磁性传感器圆形阵列是电流非接触式测量的有效方法,因为它成本低、重量轻、线性范围大、带宽宽和噪声低。针对现有阵列式电流传感器测量偏心时存在较大电流测量误差的问题,采用一种基于导线偏心位置的区域层次分析方法。通过对载流导线不同偏心位置,赋予磁传感器不同的权重进行输出叠加,与导线中心位置输出进行对比,求得最大相对误差为1.28%,传感器线性误差为1.04%,克服了导线偏心对电流测量误差的影响,证明了该方法的可行性。

基于FDC2214的非接触式液位检测系统的设计

为解决有腐蚀性、易气化、易固化等特殊液体液位测量的问题,提出了一种基于FDC2214电容式传感器的非接触式液位测量系统。设计了由STM32F103主控芯片、FDC2214电容传感器等组成的非接触式液位测量硬件系统,通过对电容值变化量与温度的变化曲线进行数据分析,搭建了对应的温度补偿系统。此外,系统采用卡尔曼滤波算法对测量数据进行滤波处理,有效地提高了系统的测量精度和稳定性。实验测试结果表明:液位测量系统对10组不同的液位进行测量,液位计灵敏度为190.5 pF/m;液位测量系统可以在不改变液体容器结构的情况下完成液位测量;卡尔曼滤波算法可以有效提高液位计的测量精度和稳定性。

集成铁氧体的LC应变传感器的设计及测试

针对金属环境下采用LC无线无源应变传感器出现电磁信号传输失效的问题,在传感器背面集成铁氧体材料,其原理是通过抑制电磁波在金属表面的涡流效应产生的感应电动势,实现在金属环境下的电磁信号耦合测试。通过HFSS软件进行仿真验证,在金属环境下LC无线无源传感器信号失效;在传感器基底背部集成铁氧体后,通过扫频得出铁氧体可以在金属环境下实现LC传感器的电磁信号传输。对铁氧体的厚度进行参数优化,最佳厚度为0.32 mm。搭建等强度悬臂梁测试平台,结果表明,金属环境下LC传感器可以通过铁氧体实现抗金属环境干扰,频率为37.7 MHz时,LC无线无源测试系统可以很好地实现信号传输,对应的S_(11)值为-25.6 dB。对悬臂梁施加外力使其发生应变,传感器在0~1300με的应变范围内灵敏度为61.54 Hz/με。测试结果表明,铁氧体有利于实现金属环境下的LC无线无源传感器应变测试。