【作者】 何永勃；

【导师】 王化祥；

【作者基本信息】 天津大学 ， 检测技术与自动化装置， 2006， 博士

【摘要】 电学成像技术(Electrical Tomography, ET)是基于电磁场理论的新型测量技术,具有无辐射、非侵入、响应速度快、成本低廉以及可视化测量等优点,在工业测量及医学监测中具有诱人的发展前景。电容层析成像(Electrical Capacitance Tomography,ECT)和电阻层析成像(Electrical Resistance Tomography,ERT)是目前最为成熟的两种ET技术。ERT适于测量以导电性介质为连续相的介质,而ECT适于测量以非导电性介质为连续相的介质。为了拓宽ET技术的应用范围,获取更为丰富测量信息,提高测量精度,将ERT和ECT有机地进行融合,提出了ERT/ECT双模态成像技术。本课题对ERT/ECT双模态空间敏感阵列电极的数学模型、电路网络模型、传感器结构优化以及硬件系统设计等有关方面内容进行了深入研究,主要工作和结果如下:1.采用复电导率概念,提出了统一的ERT/ECT敏感场数学模型,并给出了ERT/ECT正问题的有限元求解方法;2.基于多端口电路网络理论,分析了ERT和ECT系统的多种激励模式及其独立测量数,研究了由不同激励测量模式所得到的阻抗、导纳、电压传输比和电流传输比等参数的关系,并分析了不同激励模式的图像重建算法的关系,提出了一种可减小测量信号动态范围的新的激励测量模式——共点单电极激励测量模式;3.基于敏感阵列电极等效电路分析和有限元仿真计算,分别设计了多种结构的ERT、ECT单模态及ERT/ECT双模态空间敏感阵列电极,提出了传感器结构参数优化指标,并给出了优化结果;4.构建了一套EIT成像系统和一套完整的ERT/ECT双模态成像系统,采用相同的电路拓扑结构实现了ERT和ECT的融合,该系统可实现单模态及双模态运行。图像重建软件包集成了几种典型重构算法,与硬件系统配合可进行实时成像,大量实验验证了硬件和软件系统性能。该系统具有使用灵活、可扩展性强、工作稳定可靠、测量精度高以及图像质量清晰的特点。最后,作者提出了系统进一步改进的意见。更多还原

【Abstract】 Electrical Tomography (ET) is a new measurement technique based on the theory of Electric-magnetic field. Due to the advantages of non-radiant, non-intrusive, rapid response and low cost, ET has the attractive developing potential in the field of industrial application and clinical diagnosis.Electrical Capacitance Tomography (ECT) and Electrical Resistance Tomography (ERT) are the two most developed ET methods nowadays. ERT is suitable to measure the conductive medium that is taken as the continuous phase in two-phase flow, while ECT is suitable to measure the non-conducting medium that is taken as the continuous phase in two-phase flow. In order to eliminate the conductivity limitation of the medium to be measured, a dual-mode electrical tomography (ERT/ECT) technique is proposed. Combined with ERT and ECT, the dual-mode tomography has advantages of acquiring more information and higher measurement accuracy.In this thesis, the mathematical modal and network circuit modal of the dual-mode array electrode, the sensor structure and parameter optimization and the system hardware are introduced and studied. Some main works and conclusions are as following.1. A unified mathematical modal of the ERT/ECT sensitive field is proposed based on the concept of complex conductance, and the solution of ERT/ECT forward problem is introduced using finite element method (FEM).2. On the basis of multi-terminal circuit theory, several excitation strategies and their independent measurements are analyzed. The relationship of the impedance, admittance, voltage conversion ratio and current conversion ratio derived from relative equivalent circuit of ERT/ECT sensitive field with certain excitation, as well as the relationship of the image reconstruction algorism are studied. And then a novel excitation/measuring method termed as“single electrode measurement of the common node multi-terminal circuit”that can decrease the dynamic range of the measurement signal is presented.3. ERT & ECT single mode and dual-mode array electrode are developed. Based on equivalent circuit of array electrode and FEM simulation, an objection function of更多还原