【作者】 黎光宇；

【导师】 邓湘；

【作者基本信息】 北京交通大学 ， 检测技术与自动化装置， 2011， 硕士

【摘要】 电子农业是一个新兴的学科交叉研究领域,它越来越多的受到各国政府和相关科研人员的关注。将先进的电子测量及过程控制技术应用到农业生产中,对作物的生长状态进行监测,对于农业新品种培育,植物的精细种植等均具重要意义。本论文提出了土壤环境下植物块茎生长状态监测用电阻层析成像(ERT)系统,分析了电极材料和电极阵列对ERT系统的影响,以及土壤环境对电极和激励源的要求,为适合土壤环境的ERT系统深入研究提供了理论依据。基于COMSOL软件对土壤环境下电阻成像系统敏感场的建立进行了仿真。针对相邻激励模式和相对激励模式下的电学敏感场的电势和电流密度分布进行分析,得到各自特点和其适用的不同土壤环境特点,研究了块茎位置,块茎大小,块茎个数对于土壤敏感场的影响。论文给出了针对土壤环境下敏感场测量的交流阻抗模型,并对敏感场模型进行分析。分析了激励频率和土壤电阻对电极和测量结果的影响,从而为电极设计提供指导作用。通过有限元分析和COMSOL软件仿真求解出ERT系统正问题,给出节点电位和边界电压,仿真建立了ERT系统正问题求解过程,并仿真其电压测量过程,为图像重建工作打下了基础。对等位线反投影法进行了分析和数学描述,利用MATLAB和VC++混合编程实现了该算法,同时通过加权和增加网格剖分的密度实现了对等位线反投影法的优化,分析了不同情况下图像重建的效果,以及等位线反投影法适合的激励模式和可能对图像重建造成影响的因素。更多还原

【Abstract】 ’Electronic Agriculture’is a new cross-discipline and is more and more focused by governments and relevant institutes. It is important that the advanced electronic measurement and process control technology are applied into agricultural production for the monitoring of plant tuber growing status, cultivation of new kinds of seeds, the fine cultivation of plant and so on.The ERT system used for monitoring the growth status of plant tuber in soil environment was designed in the dissertation. Effects of the electrode material and electrode array on ERT system, the demands of electrodes and exiciting sourace in soil were analyzed. It can provide the theoretical evidence for the further study of ERT system in soil environment.The simulation of sensitive field of ERT system in soil environment was complted using COMSOL software. The distributions of potential and electrical current density of electrical sensitive field in the condition of the opposite and adjacent exciting mode were analyzed. The influences of soil sensitive field caused by tuber position, size and number were studied according to the different soil characteristics.The AC impedance model in the soil environment was given and analyzed in the dissertation. Exciting frequency and soil resistance affect the electrodes and measuring results were analyzed.Thus, it could provide guidance for the electrodes design.The forward problem of ERT system was simulated employing the finite element analysis and COMSOL software.The node potential and boundary voltage were established and the solving process of forward problem in ERT system was given. Foundation of image reconstruction was built.The back projection method has been studied and the mathematical description was given. The algorithm was relized and optimized useing MATLAB and VC++. The results of image reconstruction were analyzed under the different conditions.更多还原