【摘要】：隨著我國基礎(chǔ)設(shè)施建設(shè)的高速發(fā)展，地下工程施工建設(shè)所占比重越來越大。磁共振探測技術(shù)作為一種直接探測災(zāi)害水體的方法應(yīng)用在地下工程中，對地下災(zāi)害防治起到積極作用。然而，現(xiàn)有磁共振探測儀器在地下環(huán)境探測中存在諸多不足，如儀器的體積重量較大，在狹窄的地下工程環(huán)境中不便于搬運；在數(shù)據(jù)量方面，包絡(luò)采集方式記錄信號及環(huán)境噪聲的數(shù)據(jù)量有限，不利于后期的多種消噪算法處理；上位機系統(tǒng)軟件操作步驟繁瑣，運行耗時較長等。本文針對地下探測環(huán)境和已有儀器存在的問題，在JLMRS-III型儀器設(shè)計原理基礎(chǔ)上，設(shè)計了地下工程輕便式全波磁共振系統(tǒng)接收機的整體方案，并研制了接收機樣機及配套控制軟件，通過對系統(tǒng)的室內(nèi)及野外測試驗證了系統(tǒng)可行性。 本文針對地下工程環(huán)境，結(jié)合地下磁共振信號探測基本原理，從探測領(lǐng)域和探測方式出發(fā)對接收系統(tǒng)進(jìn)行設(shè)計。在系統(tǒng)的輕便化設(shè)計方面，，本文遵循方便攜帶、容易操作、穩(wěn)定可靠的設(shè)計原則，采用平板電腦作為上位機平臺嵌入系統(tǒng)內(nèi)部，減少儀器連線，利用不銹鋼結(jié)構(gòu)搭建內(nèi)部骨架。系統(tǒng)采用模塊化設(shè)計，體積小巧，重量僅為7.5kg，為在地下工程中進(jìn)行磁共振探測提供輕便式接收機。 在提升系統(tǒng)的信號接收性能設(shè)計方面，由于地下探測空間有限，本文在對接收天線建模和理論計算的基礎(chǔ)上，提出采用接收發(fā)射分離式米級線圈感應(yīng)磁共振信號，并對該系列線圈設(shè)計了前端匹配網(wǎng)絡(luò)和后級放大單元，信號經(jīng)濾波調(diào)理后可放大80.6~130.1dB；基于低噪聲MPS-140801采集卡實現(xiàn)最高采樣率128ksps的全波磁共振信號采集，同時為使信號相位疊加更加精準(zhǔn)，設(shè)計了采集校準(zhǔn)電路產(chǎn)生校準(zhǔn)信號，使信號校準(zhǔn)精度不大于78μs；從軟件和硬件兩方面構(gòu)建系統(tǒng)時序，其中軟件方面設(shè)置系統(tǒng)的發(fā)射、能釋、切換和采集時間，硬件方面通過設(shè)計電路對發(fā)射機傳送的同步信號進(jìn)行精準(zhǔn)延時，保證系統(tǒng)時序控制的準(zhǔn)確性；為提高數(shù)據(jù)處理速率以及地下勘探效率，本文利用LabVIEW對系統(tǒng)進(jìn)行上位機軟件開發(fā)，從用戶輸入、硬件驅(qū)動和系統(tǒng)處理三個層面進(jìn)行設(shè)計：采用主線單線程局部多線程方式，利用“生產(chǎn)者-消費者”架構(gòu)對數(shù)據(jù)進(jìn)行多線程循環(huán)處理，數(shù)據(jù)處理速率較原有系統(tǒng)提升4倍以上，確保接收系統(tǒng)在地下環(huán)境中進(jìn)行大數(shù)據(jù)高效探測。 最后，本文對地下工程輕便式全波磁共振系統(tǒng)接收機進(jìn)行了整體性能測試，包括屏蔽室內(nèi)噪聲環(huán)境、儀器本底噪聲、模擬MRS信號以及儀器的野外測試。系統(tǒng)本底噪聲10.51nV，等效短路噪聲1.76nV/Hz，滿足磁共振接收系統(tǒng)的設(shè)計要求。并通過野外實驗驗證了接收系統(tǒng)穩(wěn)定性和可靠性。
[Abstract]:With the rapid development of infrastructure construction in China, the proportion of underground construction is increasing. As a direct method of detecting water bodies, magnetic resonance (MRI) technology is used in underground engineering and plays an active role in the prevention and control of underground disasters. However, the existing magnetic resonance detection instruments have many shortcomings in the detection of underground environment, such as the large volume and weight of the instrument, which is not easy to carry in the narrow underground engineering environment; Envelope acquisition method records the data of signal and environmental noise is limited, which is not conducive to the later processing of a variety of de-noising algorithms; the upper computer system software operation steps are cumbersome, running time is longer, and so on. In this paper, aiming at the problems of underground detection environment and existing instruments, based on the design principle of JLMRS-III instrument, the whole scheme of portable full wave magnetic resonance system receiver for underground engineering is designed, and the prototype of the receiver and the corresponding control software are developed. The feasibility of the system is verified by indoor and field tests. According to the underground engineering environment and combined with the basic principle of underground magnetic resonance signal detection, this paper designs the receiving system from the detection field and detection mode. In the portable design of the system, this paper follows the design principle of easy to carry, easy to operate, stable and reliable. It uses the tablet computer as the upper computer platform to embed the system, reduces the instrument connection, and builds the internal skeleton with the stainless steel structure. The system is modular, small in volume and only 7.5 kg in weight. It provides a portable receiver for magnetic resonance detection in underground engineering. In the aspect of signal receiving performance design of lifting system, due to the limited underground detection space, based on the modeling and theoretical calculation of receiving antenna, this paper proposes to adopt the receiving and transmitting separated meter coil inductive magnetic resonance signal. The front-end matching network and the back-stage amplifier unit are designed for the series of coils, the signal can be amplified 80.6130.1 dB after filtering and conditioning, and the full wave magnetic resonance signal acquisition based on low-noise MPS-140801 acquisition card is realized for the highest sampling rate 128ksps. At the same time, in order to make the signal phase superposition more accurate, the acquisition and calibration circuit is designed to generate the calibration signal, so that the signal calibration accuracy is not greater than 78 渭 s. In the aspect of switching and collecting time and hardware, the synchronous signals transmitted by the transmitter are precisely delayed by designing circuits to ensure the accuracy of the timing control of the system, in order to improve the data processing rate and the efficiency of underground exploration, In this paper, LabVIEW is used to develop the upper computer software of the system, which is designed from three aspects: user input, hardware driver and system processing: the main thread, single thread, and local multithreading are adopted. By using the "producer-consumer" architecture to process the data in multithreading cycles, the data processing rate is more than four times higher than that of the original system, which ensures that the receiving system can efficiently detect big data in the underground environment. Finally, the overall performance of portable full-wave magnetic resonance system receiver for underground engineering is tested, including shielding indoor noise environment, background noise of instrument, analog MRS signal and field test of instrument. The background noise of the system is 10.51nV and the equivalent short-circuit noise is 1.76nV / Hz. it meets the design requirements of the magnetic resonance reception system. The stability and reliability of the receiving system are verified by field experiments.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P631.2

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