基于磁共振测量的空间电磁噪声采集与评价方法研究

发布时间：2018-09-19 17:20

【摘要】：地面核磁共振探测是目前世界上唯一一种直接探测地下介质中含水体储备情况的地球物理方法,与其他地球物理方法相比,具有探测效率高、探测结果定量等优势,因而被广泛应用于水资源勘查、评价以及隧道/矿井突涌水等水灾害隐患监测领域。然而,地面磁共振探测仪器系统在进行野外探测时,由于对环境中存在的电磁噪声缺少先验认知,直接的开展探测工作,在复杂的噪声环境下可能会导致即使经过数据后处理依然无法实现磁共振信号的有效提取,从而浪费了大量人力物力资源。针对这一问题,本文提出开展基于磁共振测量的空间电磁噪声采集系统的研制,并通过对该系统获取的噪声数据进行分析,给出探测区域是否具备开展磁共振测量的必要性评价,课题研究具有重要的实际应用价值。首先,在查阅大量文献资料的基础上,通过分析磁共振环境噪声的特点,设计并实现了以MSP430为主控系统的磁共振空间电磁噪声采集系统。考虑到野外探测的便携性和稳定性,提出了基于PCB板的传感器设计方案;为了实现磁共振信号1kHz-3kHz频带内高动态范围的噪声采集,通过对接收线圈匹配网络传递函数的分析,进行了匹配电路和调理电路的设计;此外,系统还具有GPS定位实验区域和实时存储数据的功能。然后,本文提出了以特征参数拟合误差为基准开展空间电磁噪声等级划分方法研究,通过对不同含水量条件下含噪MRS信号的仿真处理,实现了不同噪声环境下对环境电磁噪声水平的三级有效划分,为实际应用提供了理论指导。最后,开展了噪声采集装置的室内外测试实验,通过对不同环境下的噪声测试,验证了所设计的噪声采集系统的性能;同时,通过对探测空间所测到的环境电磁噪声的分析评价以及与实际探测工作结果的对比,验证了本文提出的噪声等级评估方法的有效性。
[Abstract]:Surface nuclear magnetic resonance (NMR) detection is the only geophysical method in the world to directly detect water reserves in underground media. Compared with other geophysical methods, it has the advantages of high detection efficiency and quantitative detection results. Therefore, it is widely used in the fields of water resources exploration, evaluation and monitoring of water hazards such as tunnel / mine flooding. However, when the ground magnetic resonance detection instrument system carries out field exploration, due to the lack of a prior understanding of the electromagnetic noise existing in the environment, the detection work is carried out directly. In complex noise environment, even after data processing, magnetic resonance signal can not be extracted effectively, thus wasting a lot of human and material resources. To solve this problem, this paper proposes to develop a spatial electromagnetic noise acquisition system based on magnetic resonance measurement, and analyzes the noise data obtained by the system. The evaluation of the necessity of magnetic resonance measurement in the detection area is given, and the research is of great practical value. Firstly, a magnetic resonance spatial electromagnetic noise acquisition system with MSP430 as the main control system is designed and implemented by analyzing the characteristics of magnetic resonance ambient noise based on a large amount of literature. Considering the portability and stability of field detection, the sensor design scheme based on PCB board is proposed, and in order to realize the noise acquisition in high dynamic range of magnetic resonance signal (1kHz-3kHz) band, the transfer function of receiving coil matching network is analyzed. The matching circuit and conditioning circuit are designed, in addition, the system also has the function of locating the experimental area of GPS and storing data in real time. Then, based on the fitting error of characteristic parameters, the method of classification of spatial electromagnetic noise is proposed, and the simulation of noisy MRS signal under different water content is carried out. The three-level effective division of electromagnetic noise level in different noise environment is realized, which provides theoretical guidance for practical application. Finally, the indoor and outdoor testing experiments of noise acquisition device are carried out, and the performance of the designed noise acquisition system is verified by the noise test in different environments. The effectiveness of the proposed method is verified by the analysis and evaluation of the environmental electromagnetic noise measured in the detection space and the comparison with the actual detection results.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P641.7;P631

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