Polarimetric Video Impulse Radar for Landmine Detection

A full-polarimetric ultra wideband GPR front-end has been developed. The technical specifications of the radar have been determined based on the analysis of different GPR scenarios and based on user-oriented demands. The radar has been designed to meet most of these specifications and at the same time to be within a limited budget. The front-end comprises a generator section, a multi-static antenna system and a receiving unit based on a multi-channel sampling converter. The novelty aspects of the radar are: principally new antenna system, use of multiple pulse generators and compensation circuits to improve stability of the system. In comparison with commercially available video impulse GPR systems the key advantages of the front-end are the considerably larger bandwidth, the ability to measure the polarimetric structure of the scattered field and the high precision of scattered field measurements. The front-end is suitable for subsurface imaging with 3D resolution sufficient for antipersonnel mine detection and recognition.     

Data Processing and Imaging in GPR System Dedicated for Landmine Detection

Improvements of GPR technology can be attained by making adjustments specific for the application of landmine detection on three levels: system design, data acquisition and data processing. In this paper we describe data processing algorithms specially developed for a novel video impulse ultra-wide band front end. With this front end, three-dimensional measurements (C-scans) have been carried out over a controlled test site, using a non-metallic scanner. The test site contained surface-laid and shallow buried landmines, both antitank and antipersonnel, made of plastic, wood, and metal. Because of practical limitations, the data have been acquired on an irregular grid. We have designed data preprocessing and imaging algorithms such that they take into account the specific antenna geometry and its elevation above the ground as well as the irregularity of the data acquisition grid. We show that by tuning the data pre-processing and imaging to the newly designed radar front end and to the particular data acquisition strategy, we obtain clear subsurface images. The resulting images show the ability of the GPR system to detect and visualize small surface laid and shallow buried targets.     

Performance Comparison of Automated Induction-Based Algorithms for Landmine Detection in a Blind Field Test

Wideband Electromagnetic Induction (EMI) data provides an opportunity to apply robust statistical signal processing techniques to potentially mitigate false alarm rates in real-time landmine detection. This paper explores the application of matched subspace detectors (MSDs) and Support Vector Machines (SVMs) to this problem. A library of landmine responses is generated from a set of calibration data and a bank of matched subspace detectors, each designed to detect a specific mine type, is developed. Support vector machines are also considered for target/clutter discrimination. These are developed based on landmine signatures, decay rate estimates, and the outputs of matched subspace filter banks. Synthetic data sets are generated and matched subspace detectors and support vector machines are trained using this synthetic data. Receiver Operating Characteristics (ROCs) for matched subspace detectors and support vector machines are presented for both experimental and simulated data sets. The results indicate that substantial reductions in false alarm rates can be achieved using these techniques, but that simulated data sets may not provide accurate predictors of performance.     

Machine-Cell Grouping in Cellular Manufacturing Systems Using Non-traditional Optimisation Techniques - A Comparative Study

In this paper, the machine-cell grouping problem is considered with the objective of minimising the total moves and minimising the cell load variation. We first review the literature on machine-cell grouping involving meta-heuristics. Then we integrate the most powerful non-traditional algorithms, genetic algorithm (GA) and simulated annealing (SA) with the most robust computer programming language "C", for cell grouping. The computational results obtained by applying the genetic algorithm and simulated annealing are compared for their efficiency in solving the machine-cell grouping problems.     

Image Processing-Based Mine Detection Techniques: A Review

Various mine detection techniques are reviewed with particular emphasis on signal and image processing methods. Based on the target, mines are classified into two types; anti-tank mine (ATM) and anti-personnel mine (APM). Because of the variety of mine types, current mine detection techniques are diversified. The assumption is made that most mine detection techniques consist of sensor, signal processing, and decision processes. For the sensor part, ground penetration radar (GPR), infrared (IR), and ultrasound (US) sensors are reviewed and their characteristics are summarized for the corresponding output signals. For the signal processing and decision parts, a set of image processing techniques including filtering, enhancement, feature extraction, and segmentation are surveyed. Segmentation is used to extract mine signal from various competing signals. For most image processing techniques covered by this paper, mine detection related experimental results are included or reproduced from existing works.     

空调两器自动化真空箱氦检技术的研究

先进的检漏技术—氦质谱检漏技术,其在空调两器生产中的使用情况,针对存在的问题,对自动化氦检技术作了探索并实践。     

电容式微机械惯性传感器信号检测技术研究

针对具有差分电容接口的微机械惯性传感器提出了一种基于电荷放大器和相关检测技术的接口电路方案.采用电荷放大器作为电容-电压转换电路,来去除传感器本身以及传输导线引起的寄生电容的干扰.利用PSPICE模拟了桥路的不对称性对电路输出的影响,经过比较采用单载波差分电桥结构以进一步增大电容检测的灵敏度.采用相关检测技术进行解调,通过解调电路对前置输出电压和载波信号进行相关运算从而消除电路的宽频噪声;给出了包括布线、接地、去耦等电路工艺的设计原则.采用一组标定电容作为传感器的模型进行了实验,实验电路灵敏度可以达到195V/pF,最小分辨率为1fF.采用该方案能够满足对普通精度的电容式微机械惯性传感器信号的检测.     

扩散硅力敏器件CAD技术的研究：结构应力分析

本文介绍在ＩＢＭ系列及其兼容系列微型机上，实现硅压力传感器中硅杯结构的应力分析方法和软件。该软件对微机软件、硬件资源的要求很低，能对包括工艺误差在内的各种复杂的硅杯结构绘出准确的应力分析图。     

锅炉故障检测与诊断技术研究

提出了一种基于深浅两层知识的锅炉故障检测与诊断方法。深知识包括锅炉系统的结构知识、物理模型和故障模型;浅知识就是经验知识,它是专家在长期的生产实践中总结出来的故障诊断经验。根据锅炉的结构和功能,对其系统进行分级描述,逐级划分直至部件或零件。系统的分级,大大减少了求解空间,提高了诊断的实时性。     

人体无创血糖检测技术

无创血糖检测技术具有无疼痛、无感染、测量简单、测量速度快等优点,能有效地满足糖尿病人实时、频繁监测血糖浓度的需要,是血糖检测技术发展的方向.本文介绍了人体无创血糖检测各种技术的原理、特点及研究进展.指出近红外无创血糖检测是最有前景的无创血糖检测方法之一,是无创检测技术研究的热点.     

Non-Stationary Thermal Wave Mode Decomposition: A Comparative Study of EMD,HVD, and VMD for Defect Detection

Russian Journal of Nondestructive Testing - Frequency coded non-stationary thermal wave imaging (NSTWI) has been evolved as viable active infrared non-destructive testing technique for inspecting...     

产品设计中同步建模技术与传统建模技术的对比分析

在新产品开发设计工程中,复杂的设计分工,使设计人员获得数据的渠道变得多种多样.传统设计方法费时费力且效率不高,非参数据的重用和更改也一直是困扰设计人员多年的问题.一种新型的建模方法--同步建模(Synchronous Modeling)克服了传统建模方法的缺点,提出了基于特征的快速模型修改,并在UGNX7.0中得到广泛应用.     

Buried Target Imaging: A Comparative Study

A wide variety of qualitative methods have been proposed for microwave imaging. It is difficult to select only one of these methods based on a priori information and measurement equipment to achieve a reliable reconstruction. Various arrangements for antennas to be used in, for instance, have been proposed which have direct impacts on the complexity of inverse methods as well as the quality of output images. In this study, four qualitative methods of the linear sampling method (LSM), time reversal (TR), diffraction tomography (DT), and back-projection (BP) have been reviewed in a 2D scenario; the performance of the methods is compared within the same framework of a multi-static configuration. The goal is to compare their resolutions and determine their advantages and drawbacks. It is shown that LSM provides the best azimuth resolution but the worst range resolution. It is almost invariant to dielectric contrast and is appropriate for a wide range of dielectric contrasts and relatively large objects. It is also shown that at relatively low dielectric contrasts, TR images are most similar to the true object, show fewer artifacts, and offer high immunity to noise. While suffering from more artifacts due to the presence of some ghost images, DT offers the best range resolution. The results also show that BP has the worst azimuth resolution when reconstructing deeply-buried targets, although its implementation is straightforward and not computationally complex.     

Z型推进装置舵桨修理工艺概述

通过对阿克马斯特(AQUAMASTER)舵桨的故障分析和解体,提出了舵浆损坏部件的修理工艺,解决了用国产材料替代进口材料的难题,填补了船公司自行修理进口舵浆的空白。     

相对检测方法的分析和应用

介绍了一种检测中心距和对称度的综合方法,并对检具的设计要点和检测误差作了详细分析和计算,为读者提供了一种检具设计和应用的新思路.     

InSb薄膜制备工艺技术研究

本文介绍了InSb薄膜制备工艺技术的研究成果,系统地阐述了InSb薄膜的工艺机理与制备技术,指出了制备InSb薄膜过程中所需解决的技术关键,并总结了制备InSb薄膜的工艺条件和实验结果.     

车辆现代检测技术综合实验设计与开发

鉴于目前高校学生普遍存在的动手能力欠缺及现场经验不足等问题,针对城市轨道交通车辆工程专业,提出利用我校已有的虚拟仪器软硬件仪器设备,开发了车辆现代检测技术综合实验平台,并详细介绍了车辆现代检测技术综合实验的总体设计及硬件平台搭建。     

A Comparative Study of Some Two-Lobed Journal Bearing Configurations

The two-lobed configurations considered for the present study are: the elliptical bearing, offset-halves bearing and two other configurations which are geometrical variations of the first two bearing forms. A companion of their performance characteristics has been obtained by theoretical analysis. It has been shown that, unlike elliptical and offset-halves bearings, which have only limited range of effective dynamic performance, a two-lobe configuration can provide consistently good dynamic performance over a wide range of load conditions.     

供应链体系结构的比较研究

论述了供应链体系结构研究的意义,指出面向供应链的企业集成是研究、开发、实践先进控制理论和技术的结果,介绍了供应链体系结构的研究现状和几个重要的模型,包括供应链作业参考模型、供应链开发模型等,对这些模型进行了比较和概括,并阐述了供应链性能的评价方法。     

A Comparative Study on Asperity Peak Modeling Methods

The peak identification scheme based method(three-point definition) and the spectral moments based method(spectral moment approach) are both widely used for asperity peak modeling in tribology. To discover the differences between the two methods, a great number of rough surface profile samples with various statistical distributions are first randomly generated using FFT. Then the distribution parameters of asperity peaks are calculated for the generated samples with both methods. The obtained results are compared and verified by experiment. The variation rules of the differences between the two methods with statistical characteristics of rough surfaces are investigated. To explain for the discovered differences, the assumptions by spectral moment approach that the joint distribution of surface height, slope and curvature is normal and that the height distribution of asperities is Gaussian, are examined. The results show that it is unreasonable to assume a joint normal distribution without inspecting the correlation pattern of [z], [z′] and [z′′], and that the height distribution of asperities is not exactly Gaussian before correlation length of rough surface increases to a certain extent, 20 for instance.