Planetary exploration using a small electromagnetic sensor

A prototype broadband electromagnetic (EM) sensor, GEM-5, has been built and tested as a possible new probe for the future Mars rover to seek an ice-bonded layer at a given depth below the Martian surface. The sensor, with a vertical coaxial coil configuration, will measure the terrain resistivity and susceptibility to determine lateral variations in resistivity and magnetic susceptibility. The lateral variations will indicate regions of resistivity/susceptibility anomalies that may contain ice or water at depth. The forward solution for the sensor geometry over a layered formation and inverse algorithms to convert the EM data into the apparent susceptibility and resistivity are developed to investigate the ability of the sensor in detecting and resolving a buried (wet) ice layer in Mars-like geologic formations. Based on the simulated study, we find that the prototype sensor design should be able to resolve the lateral variations in resistivity/susceptibility under conditions of the Martian subsurface.     

A rapid-response, high-sensitivity nanophase humidity sensor for respiratory monitoring

An ionic-type humidity sensor based on a plasma-deposited nanophase Si thin film was developed. Detection of relative humidity cycles between 20% and 90% was possible in /spl les/0.2 s with /spl sim/5 orders of magnitude variation in conductance. Such superior performance is attributable to the unique arrayed column-void network structure and ultrafine thickness (e.g., 50 nm) of the Si film as well as to the lateral electrode configuration. Our sensor can be miniaturized, integrated with signal processing circuits, and fabricated on plastics. A crucial implementation, where our sensor would be very suitable and beneficial, is respiratory monitoring.     

低功耗蓝牙DA14585的无线传感器网络应用分析

本文以低功耗蓝牙芯片DA14585为研究对象,对其基础上的无线传感网络技术应用进行分析。通过对基本概念的简要描述,分析低耗蓝牙无线传感网络中的设计要点,并在具体传感技术条件上,对硬件配置、软件设计、路由协议这三方面内容进行分析,为低功耗蓝牙技术的物联网应用提供参考依据。     

LIDAR Sensing for Vehicle Lateral Guidance: Algorithm and Experimental Study

This paper describes a new vehicle detection system based on a laser imaging, detection, and ranging (LIDAR) sensor, and conducts an experimental study to investigate the sensor's role in the current California PATH vehicle lateral guidance systems. The LIDAR sensor is installed on a controlled vehicle and it can measure the relative distance of the vehicle from a preceding vehicle, by scanning the horizontal plane with laser beams. Environmental clutter becomes the main challenge in data processing, when LIDAR tries to track the desired target. A probabilistic data association-based algorithm has been developed to solve this problem, which has been verified in real-time experiments using two Buick LaSabre vehicles. The experimental study also reveals the relation between the LIDAR outputs and the magnetic reference system widely used by the current PATH lateral control systems, and the results provide the guidelines on how this new sensor system may be used for vehicle lateral guidance     

基于硅压阻式传感器与光纤传感的静压桩贯入模型试验应用研究

将微型硅压阻式土压力传感器、孔隙水压力传感器及增敏微 型光纤光栅(fiber Bragg grating,FBG)应变传感器应用于静压桩贯入模型试验中,很好地测试了静 压桩贯入过程桩端 阻力、桩身轴力、桩土界面土压力和孔隙水压力。初步试验表明,微型硅压阻式土压力传感 器、孔隙水压 力传感器及增敏微型FBG应变传感器应用在静压模型桩贯入过程中,实现了贯入过程的桩端 阻力、桩身轴 力、桩土界面土压力和孔隙水压力的实时监测;桩身轴力和桩土界面有效侧向压力均随贯入 深度的增加而 增加,但同一深度处侧向压力逐渐减小。为静压桩贯入测试方法提供了参考依据,对进一步 研发室内试验微型传感器具有参考价值。     

Industrial Applications of the BOTDR Optical Fiber Strain Sensor

The Brillouin optical time-domain reflectometer (BOTDR) is a distributed optical fiber strain sensor whose operation is based on Brillouin scattering, and BOTDR equipment has been developed for practical use in the field of civil engineering. This equipment can measure continuous strain along an optical fiber over a distance of 10 km. Because of this advantage, it has been expected that BOTDRs would be used to detect deformations or diagnose problems in large-scale structures such as buildings, tunnels, and levees. In fact, a number of feasibility studies on the use of BOTDRs have been undertaken.This paper describes the principle of strain measurement using a BOTDR and its basic configuration. Then we introduce recent examples where BOTDRs have been applied to actual structures. We describe results of three field tests, namely, as a damage-detection system for America's Cup yachts, as an optical fiber sensor for detecting changes in river levees, and as a strain-sensing optical fiber embedded in concrete structures.     

A sensitivity and linearity improvement of a 100-dB dynamic range CMOS image sensor using a lateral overflow integration capacitor

In a CMOS image sensor featuring a lateral overflow integration capacitor in a pixel, which integrates the overflowed charges from a fully depleted photodiode during the same exposure, the sensitivity in nonsaturated signal and the linearity in saturated overflow signal have been improved by introducing a new pixel circuit and its operation. The floating diffusion capacitance of the CMOS image sensor is as small as that of a four transistors type CMOS image sensor because the lateral overflow integration capacitor is located next to the reset switch. A 1/3-inch VGA format (640/sup H//spl times/480/sup V/ pixels), 7.5/spl times/7.5 /spl mu/m/sup 2/ pixel color CMOS image sensor fabricated through 0.35-/spl mu/m two-poly three-metal CMOS process results in a 100 dB dynamic range characteristic, with improved sensitivity and linearity.     

Polarisation-induced visibility limits in interferometric fibre-optic sensor arrays

Polarisation-induced fading is analysed in Mach-Zehnder-type interferometric fibre-optic sensor arrays. Given a sensor array configuration and the polarisation properties of individual elements, a procedure is presented to find an optimal input state of polarisation which maximises overall sensor visibility. It is shown that for both serial and parallel arrays with N sensor elements, the visibility of the worst-case sensor configuration can be maximised to a value of sin ( pi /2N).<>     

基于长标距FBG应变传感器的筒仓拆除实时监测

为确保大连华能混凝土筒仓在物理开凿拆除过程中施工人员和施工机械的安全,设计了长标距光纤光栅(FBG)应变传感器进行全过程实时监测。通过对传感器采集的应变数据进行静力和动力分析,得到筒仓结构表面应变和固有频率随开孔率的变化情况,进而对结构损伤情况进行识别。在混凝土筒仓监测过程中,该传感器运行稳定,获得了整个拆除过程中结构应变响应数据,并对结构倒塌做出预警,混凝土筒仓成功按照预定方位倒塌。此研究成果解决了传统拆除作业中的盲目性及安全措施延时被动的问题,为同类混凝土拆除工作提供了重要的技术参考。     

Appropriate Sensor Placement for Fault-Tolerant Lane-Keeping Control of Automated Vehicles

This paper deals with the sensor placement problem in the realization of failure-tolerant lane-keeping control of front-wheel-steered automated vehicles. The scenario considered is one in which lane-keeping action is performed using two sensors that independently measure the lateral deviation of their locations of installation from a reference. The problem of interest is to determine appropriate locations for their installation so that the vehicle can be steered safely even in the event of failure of one of the two sensors. It is shown that for safe lane-keeping action at low as well as high speeds, both sensors should be placed ahead of the rear axle of the vehicle. In addition, the paper discusses a pedagogical problem - namely, the lane-keeping control problem with lateral error information from a sensor placed behind the rear axle. It is shown that, contrary to intuition, it is easier to steer the vehicle at higher speeds. Results based on experiments conducted on vehicles used in the Partners for Advanced Transit on Highways (PATH) program demonstrate the validity of analytical predictions.     

A Polymer Microdisk Photonic Sensor Integrated Onto Silicon

Optical sensors are attractive for integrated chip-scale sensor systems. In this letter, integrated microdisk sensors have been fabricated and characterized for five different D-glucose concentrations in deionized water. The microdisk sensor reported is in an orthogonal configuration, reducing the sensor size toward chip-scale sensor applications. The measured wavelength shift in the resonant peak of the microdisk sensors has a linear response as a function of D-glucose concentration. The estimated sensitivity (defined by$Delta lambda_ resonant$/wt%$_ D-glucose$) of the fabricated microdisk sensor for the D-glucose solution was 0.12[nm/wt%] based on the slope of the linear regression line from the measured results.     

Automated vehicle guidance using discrete reference markers

Techniques for providing steering control for an automated vehicle using discrete reference markers fixed to the road surface are investigated analytically. Either optical or magnetic approaches can be used for the sensor, which generates a measurement of the lateral offset of the vehicle path at each marker to form the basic data for steering control. Possible mechanizations of sensor and controller are outlined. Techniques for handling certain anomalous conditions, such as a missing marker, or loss of acquisition, and special maneuvers, such as u-turns and switching, are briefly discussed. A general analysis of the vehicle dynamics and the discrete control system is presented using the state variable formulation. Noise in both the sensor measurement and in the steering servo are accounted for. An optimal controller is simulated on a general purpose computer, and the resulting plots of vehicle path are presented. Parameters representing a small multipassenger tram were selected, and the simulation runs show response to an erroneous sensor measurement and acquisition following large initial path errors.     

Modified linear prediction method for directions of arrivalestimation of narrow-band plane waves

A modified linear prediction (MLP) method is proposed in which the reference sensor is optimally located on the extended line of the array. The criterion of optimality is the minimization of the prediction error power, where the prediction error is defined as the difference between the reference sensor and the weighted array outputs. It is shown that the L₂-norm of the least-squares array weights attains a minimum value for the optimum spacing of the reference sensor, subject to some soft constraint on signal-to-noise ratio (SNR). How this minimum norm property can be used for finding the optimum spacing of the reference sensor is described. The performance of the MLP method is studied and compared with that of the linear prediction (LP) method using resolution, detection bias, and variance as the performance measures. The study reveals that the MLP method performs much better than the LP technique     

Sensor Configuration and Activation for Field Detection in Large Sensor Arrays

The problem of sensor configuration for the detection of correlated random fields using large sensor arrays is considered. Using error exponents that characterize the asymptotic behavior of the optimal detector, the detection performance of different sensor configurations is analyzed and compared. The dependence of the optimal configuration on parameters such as sensor signal-to-noise ratio (SNR), field correlation, etc., is examined, yielding insights into the most effective choices for sensor selection in various operating conditions. Simulation results validate the analysis based on asymptotic results for finite sample cases.     

一种新型高量程微加速度传感器侵彻测试

设计一种新型高量程压阻式微加速度传感器,并将其应用于对钢靶和混凝土靶进行100 000 g以上的侵彻测试。实验结果表明,该传感器在侵彻钢靶具有良好的抗过载能力。对实测过载时程曲线进行系统分析,结果表明该传感器与988传感器的侵彻过载数据基本吻合;侵彻混凝土靶时出现传感器梁断裂现象,需进一步从封装方面改进。     

弹体侵彻中加速度计的机械滤波仿真研究

利用ANSYS/LS-DYNA软件对弹体侵彻混凝土靶板过程中,不同的机械滤波材料滤波能力进行了仿真分析。研究了应用于加速度传感器的不同滤波材料对加速度激励信号的影响,分析结果显示,0.5cm厚低密度聚乙烯材料在弹体侵彻混凝土靶板中可以起到较好的机械滤波器的作用,达到了对高过载环境下加速度计的滤波、保护目的。     

基于SVPWM的永磁同步电机控制系统建模与仿真

针对永磁同步电机结构复杂、模型非线性从而导致难以控制的问题,在分析永磁同步电机数学模型和SVPWM算法的基础上,利用Matlab/Simulink设计了一种基于SVPWM的永磁同步电机双闭环控制系统新模型,给出各子模块的具体设计模型。对＂积分斜率法＂产生三角波脉冲的方法进行了改进,最后对整个系统进行了仿真实验。仿真结果验证了该模型的正确性和有效性,为实际PMSM控制系统的设计提供了参考依据。     

一种新型高量程微加速度传感器侵彻测试

设计一种新型高量程压阻式微加速度传感器.并将其应用于对铜靶和混凝土靶进行100000 g以上的侵彻测试.实验结果表明,该传感器在侵彻钢靶具有良好的抗过载能力.对实测过栽时程曲线进行系统分析,结果表明该传感器与988传感器的侵彻过载数据基本吻合:侵彻混凝土靶时出现传感器粱断裂现象.需进一步从封装方面改进.     

基于偏振干涉的光纤光栅无线传感网络系统

将光纤光栅传感与无线传输相结合,建立传感节点光路结构理论模型,分析了结构参数对光纤环镜(FLM)特性的影响。以数学模型为依据,优化了S-MAC协议的工作时间、休眠时间等参数,时延和能耗都有很好的改善。设计了基于保偏结构的光纤光栅无线传感网络(WSN)和基于LabVIEW的参数测定软件、解调系统监控软件。参数测定软件使得系统脱离实验室进入应用领域;对无线网络传输结构和S-MAC协议优化的研究为网络节点的可移动和可重布提供了保障。     

An IPv6 address configuration scheme for wireless sensor networks based on location information

The paper proposes an IPv6 address configuration scheme for wireless sensor networks based on sensor nodes’ location information. The scheme divides WSN into multiple clusters based on sensor nodes’ location information and proposes the IPv6 address structure for sensor nodes based on their location information. In the scheme, a cluster head combines the stateless configuration strategy and the stateful configuration strategy to assign the IPv6 addresses for the cluster members in the same cluster. In the stateless configuration strategy, a cluster head employs the hash division method to configure the IPv6 addresses for the cluster members and utilizes the linear probing method to solve the address collision, and the DAD for the IPv6 addresses assigned for the cluster members is only performed within the cluster where the cluster members locate. In addition, the IPv6 address configuration for the cluster members in the different clusters can be performed simultaneously, so the IPv6 address configuration delay time is shortened and the IPv6 address configuration cost is reduced. The paper analyzes the performance parameters of the proposed scheme, Strong DAD and MANETConf, including DAD cost, address configuration cost and address configuration delay time, and the analytical results show that the performance of the proposed scheme is better than Strong DAD and MANETConf.