NON-DESTRUCTIVE PAVEMENT LAYER THICKNESS MEASUREMENT USING EMPIRICAL MODE DECOMPOSITION WITH GPR

Ground Penetrating Radar （GPR） is an effective Non-Destructive Testing （NDT） technique for highway pavement surveys, which is able to acquire continuous pavement data compared with traditional core drilling method. In this study, we proposed an accurate and efficient method to estimate the thickness of each pavement layer using an air-coupled GPR system. For this work, the main difficulties are estimating each pavement layer＇s time delay and dielectric constant. We first give the basic signal model for pavement evaluation, and then present an Intrinsic Mode Functions （IMFs） product detector to determine each pavement layer＇s time delay. This method is based on Empirical Mode Decomposition （EMD）, which is an adaptive signal decomposition procedure and proved to be suitable for suppressing noises in GPR signal. The dielectric constant was determined by metal reflection measurement. The laboratory and highway experiments illustrate that the proposed thickness estimation method yields reasonable result, thus meets the requirements of practical highway pavement survey with massive GPR data.     

基于UML状态图的类状态测试

在介绍UML状态图的基础上,以面向对象软件的类作为基本测试单元,研究了基于UML状态图的类状态测试技术,并在Eclipse平台上结合Java工具用手工选择测试数据进行了实例测试.     

高密度封装技术推动测试技术发展

高密度封装技术的飞速发展也给测试技术提出了新挑战。为了应对挑战,新的测试技术不断涌现。对几种新型测试技术的特点及未来测试技术的发展趋势进行了初步分析。     

基于卫星导航系统地面段的可靠性测试方法研究

本文对卫星导航系统单机设备和地面运控系统分别作为研究对象进行了研究：根据单机设备的特性,分别研究了成败型测试方法、寿命型测试方法和应力一一强度型测试方法;根据地面运控系统的组成特点,进行了并联系统测试方法研究和串联系统测试方法研究,并在研究基础之上,提出了如何在后续系统研制建设过程中继续加强可靠性测试工作的对策。     

全自动太阳能电池测试分选设备的研制

太阳能电池测试分选设备是晶体硅太阳能电池生产专用设备,可用于太阳能电池转换效率以及电性能参数测量。所有的测量结果可以自动分类,自动保存。该设备在测试系统设计、分选结构设计、步进电机精密驱动、高速数据交换和电气控制等技术方面达到较高水平。该设备具有全自动化,操作简便,测试精确,运行稳定,碎片率低、生产效率高等特点,性能完...     

高频编码信号采集与存储系统研究

为了能够在速度快、频率高、冲击大、体积小等恶劣环境下,精确测得高频编码信号。设计了有针对性的采集、存储系统。通过分析信号特点,选取高性能匹配芯片EP3C16作为主控制器。考虑电磁干扰等因素,利用Cadence软件进行高速PCB设计,并对电阻匹配网络进行设计仿真,数据存储采用乒乓存储技术,并利用Quartus II进行模拟仿真。在电路板布线、阻抗设计上都进行了相应地抗干扰预防处理。应用设计的系统对500MHz实测信号进行采集验证,结果证明了系统具有抗干扰、稳定、可实现的特点。     

棉织物酶整理程度的监测方法

棉织物的纤维素酶整理能改善织物表面形态和风格，但控制不当会严重损伤织物强度。本文讨论了对纤维素酶促水解反应程度的监测方法，将减量率与还原糖产率相关联，提出一种简捷可靠的判断水解程度的方法，以求为棉织物酶整理提供工艺控制的依据。     

无醛或低醛树脂整理剂的筛选和应用

针对甲醛对人体的危害，介绍了国内外甲醛在内衣和外衣上的最低限量标准；并对国内外生产的服装衬样品进行了成品释放甲醛量的测试；最后筛选了无醛和低醛树脂整理剂并在服装衬布上应用。     

Analysis of Leakages in a Solid Oxide Fuel Cell Stack in a System Environment

A solid oxide fuel cell (SOFC) stack can exhibit both anodic and cathodic leakages, i.e. a fuel leak from the anode side and an air leak from the cathode side of the stack, respectively. This study describes the results of an in‐situ leakage analysis conducted for a planar SOFC stack during 2000 hours of operation in an actual system environment. The leakages are quantified experimentally at nominal system operating conditions by conducting composition analysis and flow metering of gases for both fuel and air subsystems. Based on the calculated atomic hydrogen‐to‐carbon ratio of the fuel and air gases, it is found that the fuel leakages are mostly selective by nature: the leaking fuel gas does not have the same composition as the fuel system gas. A simple diffusive leakage model, based on the leakage being driven by concentration differences weighted by diffusion coefficients, is applied to quantify the amount of leakages. The leakage model provides a good correspondence with the experimental results of the gas analysis.     

高温抗折试验的应力增加速率问题

本文从标准规定应力增加速率为一恒量出发，根据加荷、应力对时间的函数关系，讨论了抗折仪满足标准要求应具备的测试功能及加荷达率的确定。