【作者】 王斌斌；

【导师】 董峰；

【作者基本信息】 天津大学 ， 检测技术与自动化装置， 2007， 硕士

【摘要】 电阻层析成像(ERT)技术是近年来发展起来的一种高新的检测技术,可实现对封闭的管道或过程容器设备内部多相组分物质参数的可视化测量,具有非侵入、无辐射、在线检测等优点,在两相/多相流检测中有广阔的应用前景。目前不能广泛应用于工业在线检测,主要原因是由其实时性造成的。本课题从电阻层析成像数据采集系统的实时性入手分析,设计一套ERT并行数据采集系统,主要的研究工作和结果如下:1.完成ERT并行数据采集系统的实时性分析。通过对数据采集过程中耗时巨大的低通滤波环节的理论分析和仿真验证,得出60KHz～200KHz激励信号通过低通滤波器的稳定时间,计算出ERT并行数据采集系统在不同频率的激励信号下的数据采集速度,当系统采用60KHz频率的正弦波信号激励时,系统的数据采集速度理论值可以达到742幅/秒;200KHz激励时,系统数据采集速度理论值可达1366幅/秒。2.实现ERT并行数据采集系统的平台设计。在实时性分析的基础上,采用基于PCI总线的数字I/O卡和数据采集卡设计了一套ERT并行数据采集系统,利用自定义总线将系统内部的结构单元模块化。该系统包括信号发生、电极传感器阵列、数据采集、数据预处理、逻辑时序、信号背板等部分;在数据预处理和数据采集部分,采用16通道并行传输,包括16通道的差动放大、16通道的解调滤波和16通道的AD转换。3.调试各个功能模块,并能测量管道内部电势场的分布情况,初步分析ERT并行数据采集系统测量值的完整性和有效性。更多还原

【Abstract】 Electrical Resistance Tomography (ERT) is a novel cross section measurement technology developed in recent years. It can achieve the visualization measurement of multi-phase media component parameter in the closed pipe and process vessel inside. And it has the virtue of non-intrusive, non-radiation and on-line visual monitoring. And it is now in a great prospective in two-phase flow. At present, there are still some difficulties in its implementation in the industrial field because the real-time performance of ERT can’t satisfy the speed requirement for on-line measurement. This dissertation begins with the analysis of real-time performance of the ERT system and presents a new ERT system with parallel data acquisition strategy. The main researches are as follow:1. The real-time performance of the parallel data acquisition system for ERT is analyzed. The low-pass filter (LPF), which costs the most time of the data acquisition process, is simulated. The response times of LPF and data acquisition speed are investigated when the band of the signal frequency is from 60 KHz to 200 KHz. When the frequency is 60 KHz, the data acquisition speed can achieve at 742 frames per second; when the frequency is 200 KHz, the data acquisition speed can achieve at 1366 frames per second.2. The parallel data acquisition system for ERT is presented. Basing on the analysis of real-time performance, an I/O card and two data acquisition cards which are based on PCI bus are used in this system. And system is module structured with the user-defined bus This ERT system consist of the exciting signal source module, the sensor and selection logic module, DAS module, signal pretreatment module, logic and time module and the baseboard. The DAS module and signal pretreatment module consist of 16 groups of amplifiers, 16 groups of demodulators and filters and 16 groups of AD.3. The modules are individually tested and the distribution of the sensing field is measured preliminarily with complete and valid signals.更多还原