【摘要】：近年來,隨著地磁傳感器儀器的探測精度和探測速度的不斷提高,人們可以獲得大量的高精度地磁數(shù)據(jù),這使得地磁探測在各種應(yīng)用領(lǐng)域中有著更為廣闊的應(yīng)用前景。地磁探測中,確定目標(biāo)物體的位置是一項(xiàng)首要任務(wù),是進(jìn)行后續(xù)工作的前提。由于鐵磁性目標(biāo)的存在,其自身的固有磁場和產(chǎn)生的感應(yīng)磁場會疊加到地磁場上,從而導(dǎo)致空間地磁場分布的變化,進(jìn)而在該空間中產(chǎn)生磁異常。人們通過對磁異常的分析和反演,可以有效的獲得該目標(biāo)物體的位置,達(dá)到定位的目的。因此研究如何利用磁異常進(jìn)行磁性目標(biāo)定位具有重要的學(xué)術(shù)和實(shí)際意義。高精度的磁測儀器(光泵磁力儀,超導(dǎo)量子干涉儀等)在國內(nèi)外的地磁探測中得到廣泛的應(yīng)用。這些儀器具有較高的測量精度和穩(wěn)定性,同時(shí)能夠連續(xù)測量,為獲得可靠的地磁數(shù)據(jù)提供了必要的保障。但是在利用磁異常進(jìn)行目標(biāo)定位過程中,仍然存在一些重要的技術(shù)難點(diǎn),如:目標(biāo)磁異常的提取,地磁圖的空間插值技術(shù),測量過程中噪聲的抑制方法以及定位算法等。本論文針對上述問題展開研究,研究工作主要集中在以下幾個(gè)方面:目標(biāo)磁異常的提取是磁性目標(biāo)定位中關(guān)鍵任務(wù)。地磁場可以分解為地磁正常場和異常場兩部分,異常場是相對于正常場而言的,是由于磁性目標(biāo)的存在而產(chǎn)生的。由于選取的地磁正常場不同,故計(jì)算出的異常場也不完全相同。為了獲得準(zhǔn)確的磁異常,需要構(gòu)建合理的地磁正常場模型。地磁場模型分為全球模型與區(qū)域模型。相比于全球模型,區(qū)域模型更能夠精細(xì)地描繪該區(qū)域內(nèi)的磁場分布。準(zhǔn)確構(gòu)建區(qū)域的地磁正常場模型決定了目標(biāo)磁異常提取的準(zhǔn)確程度。本文分析了兩種構(gòu)建局部區(qū)域地磁場的模型:多項(xiàng)式模型和Spline模型,并對比了兩種模型的優(yōu)缺點(diǎn),分析了兩種模型存在的問題,給出了提高精度的應(yīng)對措施和最佳模型選擇方案。地磁圖是描繪磁異常分布的手段和工具,同時(shí)地磁圖數(shù)據(jù)是進(jìn)行定位的關(guān)鍵。由于實(shí)際測量中很難能實(shí)現(xiàn)大規(guī)模的地磁測量條件而獲得足夠的測量數(shù)據(jù),因此,需要通過空間插值方法來提高測量數(shù)據(jù)的密度,從而提高磁異常的精度�？死锝鸩逯捣ㄔ诒憩F(xiàn)屬性的空間相關(guān)性的問題上有很高的逼近程度,因此,本文將克里金插值法做為地磁圖繪中的插值方法。文中從數(shù)學(xué)原理出發(fā),探析了該插值方法的數(shù)學(xué)原理。克里金插值方中的變異函數(shù)則能夠反映局部范圍和特定方向上特征的變化,因此,變異函數(shù)決定了插值精度。插值過程中的變異函數(shù)是實(shí)驗(yàn)變異函數(shù)和理論變異函數(shù)的擬合結(jié)果。本文提出了基于粒子群算法的變異函數(shù)擬合法,有效提高了變異函數(shù)的擬合精度,從而提高了地磁圖繪制的準(zhǔn)確程度。通過實(shí)驗(yàn)驗(yàn)證了基于粒子群算法擬合得到的變異函數(shù)在插值過程中的效果好,插值得到的地磁圖的精度也很高。實(shí)際地磁測量過程中的噪聲會對測量數(shù)據(jù)造成干擾,影響測量數(shù)據(jù)的精度。為了提高數(shù)據(jù)的質(zhì)量,需要消除地磁信號中的噪聲。地磁噪聲的頻帶較寬,很難通過頻率分離的方式將噪聲分離處理。由于信號和噪聲在小波域有不同的表現(xiàn)形式,小波去噪是通過它們的小波系數(shù)幅值隨尺度變化的趨勢不同,達(dá)到分離噪聲的目的。本文針對小波閾值去噪中傳統(tǒng)的閾值函數(shù)存在著一些缺點(diǎn),提出了一種閾值可以動態(tài)調(diào)整的閾值函數(shù),有效避免軟閾值方法中對于絕對值較大的小波系數(shù)與其處理后的小波系數(shù)估計(jì)值相比總有固定偏差,且產(chǎn)生恒定衰減的不足。同時(shí)針對如何選擇合適的閾值問題,給出了閾值選取的方法。仿真結(jié)果表明:改進(jìn)后的小波去噪方法能夠有效的去除信號中地磁噪聲,從而提高測量數(shù)據(jù)的精度。目標(biāo)定位算法研究。鐵磁性目標(biāo)能夠?qū)е缕淇臻g地磁場分布發(fā)生變化,形成磁異常。.人們通過分析和處理相應(yīng)的磁異常,可以實(shí)現(xiàn)對磁性目標(biāo)的定位。目前現(xiàn)有的定位算法中需事先已知目標(biāo)體的類型,但在對未知目標(biāo)實(shí)施定位時(shí),這一條件很難滿足。因此,本文提出了一種基于小子域的定位方法。該定位方法來源于小子域?yàn)V波算法,通過改進(jìn)使其能夠在不依賴于任何先知條件下,通過對磁異常自動壓縮的方式確定磁性物體的位置。通過理論仿真,結(jié)果表明基于小子域的定位方法能夠準(zhǔn)確的確定磁性物體的位置。磁性目標(biāo)定位的實(shí)驗(yàn)。為驗(yàn)證以上理論研究的正確性與有效性,本文開展了磁性目標(biāo)定位的實(shí)驗(yàn)。實(shí)驗(yàn)表明:改進(jìn)后的小波去噪方法可以提高地磁信號的信噪比,從而提高了地磁數(shù)據(jù)的精度;利用去噪后的地磁數(shù)據(jù)構(gòu)建該區(qū)域的泰勒多項(xiàng)式地磁場模型,計(jì)算出高精度的目標(biāo)磁異常;通過改進(jìn)后的克里金插值方法,獲得磁異常的空間分布;通過小子域定位算法對空間磁異常的數(shù)據(jù)進(jìn)行處理,實(shí)現(xiàn)了對磁性目標(biāo)的定位。
[Abstract]:In recent years, with the improvement of detection precision and detection speed of geomagnetic sensors, a large number of high-precision geomagnetic data can be obtained, which makes geomagnetic detection have a broader application prospects in various fields. Because of the existence of ferromagnetic target, its inherent magnetic field and induced magnetic field will be superimposed on the geomagnetic field, which will lead to the change of geomagnetic field distribution in space, and then produce magnetic anomaly in the space. Therefore, it is of great academic and practical significance to study how to use magnetic anomalies to locate magnetic targets. High-precision magnetic measuring instruments (optical pump magnetometer, superconducting quantum interferometer, etc.) have been widely used in geomagnetic detection at home and abroad. These instruments have high measuring accuracy and stability, and can be continuously measured for However, there are still some important technical difficulties in the process of using magnetic anomalies to locate targets, such as the extraction of magnetic anomalies, the spatial interpolation of geomagnetic maps, the method of noise suppression and location algorithm in the process of measurement. The research work mainly focuses on the following aspects: the extraction of magnetic anomaly is the key task of magnetic target localization. The geomagnetic field can be divided into two parts: normal field and anomalous field. The anomalous field is relative to the normal field, which is caused by the existence of magnetic target. In order to obtain accurate magnetic anomalies, it is necessary to construct a reasonable geomagnetic normal field model. The geomagnetic field model is divided into global model and regional model. The accuracy of target magnetic anomaly extraction is analyzed in this paper. Two geomagnetic anomaly models, polynomial model and Spline model, are constructed. The advantages and disadvantages of the two models are compared. The problems of the two models are analyzed, and the measures to improve the accuracy and the best model selection scheme are given. Because it is difficult to achieve large-scale geomagnetic survey conditions and obtain sufficient measurement data in actual surveys, it is necessary to use spatial interpolation method to improve the density of measurement data, thereby improving the accuracy of magnetic anomalies. In this paper, the Kriging interpolation method is used as an interpolation method in geomagnetic mapping. Based on the mathematical principle, the mathematical principle of the interpolation method is discussed. The variation function in the Kriging interpolation square can reflect the change of the local range and the characteristic in the specific direction. The variance function in the interpolation process is the fitting result of the experimental and theoretical variance functions. In this paper, a variance function fitting method based on particle swarm optimization is proposed, which can effectively improve the fitting accuracy of the variance function and thus improve the accuracy of geomagnetic map drawing. In order to improve the quality of the data, it is necessary to eliminate the noise in the geomagnetic signal. Because signals and noises have different forms in wavelet domain, wavelet de-noising can separate noises by their amplitudes varying with scales. In this paper, some shortcomings of traditional threshold function in wavelet threshold de-noising are pointed out. A threshold function which can dynamically adjust the threshold value is proposed to avoid the invariable attenuation of the wavelet coefficients with large absolute value in soft threshold method. The real results show that the improved wavelet de-noising method can effectively remove the geomagnetic noise in the signal and improve the accuracy of the measurement data. Research on target location algorithm. The existing localization algorithms need to know the type of target in advance, but it is difficult to satisfy this condition when locating unknown target. Therefore, this paper proposes a localization method based on small subdomain. This localization method is derived from small subdomain filtering algorithm and can be improved to be independent of any prophet. In order to verify the correctness and validity of the above theoretical research, the magnetic object location is carried out in this paper. Experiments show that the improved wavelet de-noising method can improve the signal-to-noise ratio of geomagnetic signals and thus improve the accuracy of geomagnetic data; the Taylor polynomial geomagnetic field model of this region is constructed by using the de-noised geomagnetic data, and the high-precision target magnetic anomaly is calculated; the space of magnetic anomaly is obtained by the improved Kriging interpolation method. Distribution between magnetic objects and magnetic anomaly data are processed by small subdomain localization algorithm.
【學(xué)位授予單位】：哈爾濱工程大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：P318.63;TP212.9

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本文編號：2192098