本文主要研究内容
作者赵小宇（2019）在《瞬变电磁场波场变换与合成孔径成像理论研究》一文中研究指出：瞬变电磁(Transient Electromagnetic,TEM)信号由于其本身扩散场特性,分辨能力较弱,探测精度不高。而波动场则表现出较好的特性,对目标的分辨能力更高所谓瞬变电磁场波场变换是指,将时域低频电磁场通过数学变换转换成满足波动方程的虚拟波场,然后借助于波场中发展起来的一些较为成熟的解释方法和技术对这种计算出来的“波场”进行分析和处理,从而达到探测地下目标体,提高瞬变电磁法的分辨率和解释精度的目的本文首先推导了适用于多种电磁场分量(电场、磁场、感应电动势)的波场变换方程。由于波场变换式属于第一类Fredholm方程,由扩散场求对应的波场为不适定逆问题。考虑到共辄梯度法(Conjugate Gradient method,CG)对求解系数矩阵具有紧密簇谱的线性方程组十分有效,本文提出了一种新的预条件正则化共辄梯度法(Pre-conditioned Regularized Conjugate Gradient,PRCG)来实现扩散方程到波动方程的转换。首先,分析了积分核函数曲线特征,对几种不同离散方式进行比较,选取翠域时间窗最窄,系数矩阵条件数最小的离散方式1对方程进行离散,并构建对称正定系数矩阵;然后,将正则化算法与CG法相结合,在迭代的每一步,正则化线性系统本身用CG迭代求解。此外,正则化线性系统本身可以用SSOR预条件子进行预处理SSOR预处理有效降低了矩阵条件数,正则化改善了系数矩阵的谱特征,而CG迭代实现了全域波场计算。利用特殊子波对算法进行了验证,结果显示,波场变换解与理论解吻合很好,与RCG法及原有的PRCG法计算结果对比,证明本文算法收敛速度更快、稳定性更好利用本文设计的算法,对层状地电模型响应波场特性进行了详细分析。由G、D两层地电模型,分析了本文算法在具体参数条件下的有效分辨深度,以及对电阻率差异的敏感特性;由Q、A、H、K三层地电模型分析了层状介质的混叠干扰等影响,并给出了该算法对薄层的有效分辨能力。对含噪信号的波场变换表明,通过相应增大正则化参数,仍然可以得到非常稳定的波场变换解,证明该算法稳定、可靠,宜于实用。目前,TEM数据解释仍以单点处理为主,单点处理方法不仅造成了有效数据的浪费,而且忽视了各测点数据间的关联性。由于多孔径TEM存在类相干性,同一地质体在相邻测点上的反射回波具有较好相关性。因此,对TEM信号可以进行合成孔径成像。借鉴合成孔径聚焦超声成像技术的基本思想,本文引入“合成孔径聚焦瞬变电磁成像技术”,提出一套新的数据处理方法,即采用延时相关叠加算法,实现波束形成和多测点数据聚焦合成。在完成波场变换后,以测点为中心,相邻测点信号延时相关叠加,将传统的单点处理方式发展为多点合成方法,逐点推移、多次覆盖。由此大大提高接收线圈的孔径长度和数据的信噪比,从而提高瞬变电磁法的分辨率和解释精度。利用不同层状模型对合成孔径聚焦瞬变电磁成像理论及其方法和算法进行了验证,结果表明,该方法能够有效抑制噪声干扰,突出异常,提高瞬变电磁法对电性界面的分辨能力。对实测数据分析表明,利用瞬变电磁场波场变换与合成孔径聚焦处理能够实现对低阻矿体区成像,对低阻异常区电性界面反映较好,与电阻率反演断面图相比分辨率较高。
Abstract
shun bian dian ci (Transient Electromagnetic,TEM)xin hao you yu ji ben shen kuo san chang te xing ,fen bian neng li jiao ruo ,tan ce jing du bu gao 。er bo dong chang ze biao xian chu jiao hao de te xing ,dui mu biao de fen bian neng li geng gao suo wei shun bian dian ci chang bo chang bian huan shi zhi ,jiang shi yu di pin dian ci chang tong guo shu xue bian huan zhuai huan cheng man zu bo dong fang cheng de xu ni bo chang ,ran hou jie zhu yu bo chang zhong fa zhan qi lai de yi xie jiao wei cheng shou de jie shi fang fa he ji shu dui zhe chong ji suan chu lai de “bo chang ”jin hang fen xi he chu li ,cong er da dao tan ce de xia mu biao ti ,di gao shun bian dian ci fa de fen bian lv he jie shi jing du de mu de ben wen shou xian tui dao le kuo yong yu duo chong dian ci chang fen liang (dian chang 、ci chang 、gan ying dian dong shi )de bo chang bian huan fang cheng 。you yu bo chang bian huan shi shu yu di yi lei Fredholmfang cheng ,you kuo san chang qiu dui ying de bo chang wei bu kuo ding ni wen ti 。kao lv dao gong zhe ti du fa (Conjugate Gradient method,CG)dui qiu jie ji shu ju zhen ju you jin mi cu pu de xian xing fang cheng zu shi fen you xiao ,ben wen di chu le yi chong xin de yu tiao jian zheng ze hua gong zhe ti du fa (Pre-conditioned Regularized Conjugate Gradient,PRCG)lai shi xian kuo san fang cheng dao bo dong fang cheng de zhuai huan 。shou xian ,fen xi le ji fen he han shu qu xian te zheng ,dui ji chong bu tong li san fang shi jin hang bi jiao ,shua qu cui yu shi jian chuang zui zhai ,ji shu ju zhen tiao jian shu zui xiao de li san fang shi 1dui fang cheng jin hang li san ,bing gou jian dui chen zheng ding ji shu ju zhen ;ran hou ,jiang zheng ze hua suan fa yu CGfa xiang jie ge ,zai die dai de mei yi bu ,zheng ze hua xian xing ji tong ben shen yong CGdie dai qiu jie 。ci wai ,zheng ze hua xian xing ji tong ben shen ke yi yong SSORyu tiao jian zi jin hang yu chu li SSORyu chu li you xiao jiang di le ju zhen tiao jian shu ,zheng ze hua gai shan le ji shu ju zhen de pu te zheng ,er CGdie dai shi xian le quan yu bo chang ji suan 。li yong te shu zi bo dui suan fa jin hang le yan zheng ,jie guo xian shi ,bo chang bian huan jie yu li lun jie wen ge hen hao ,yu RCGfa ji yuan you de PRCGfa ji suan jie guo dui bi ,zheng ming ben wen suan fa shou lian su du geng kuai 、wen ding xing geng hao li yong ben wen she ji de suan fa ,dui ceng zhuang de dian mo xing xiang ying bo chang te xing jin hang le xiang xi fen xi 。you G、Dliang ceng de dian mo xing ,fen xi le ben wen suan fa zai ju ti can shu tiao jian xia de you xiao fen bian shen du ,yi ji dui dian zu lv cha yi de min gan te xing ;you Q、A、H、Ksan ceng de dian mo xing fen xi le ceng zhuang jie zhi de hun die gan rao deng ying xiang ,bing gei chu le gai suan fa dui bao ceng de you xiao fen bian neng li 。dui han zao xin hao de bo chang bian huan biao ming ,tong guo xiang ying zeng da zheng ze hua can shu ,reng ran ke yi de dao fei chang wen ding de bo chang bian huan jie ,zheng ming gai suan fa wen ding 、ke kao ,yi yu shi yong 。mu qian ,TEMshu ju jie shi reng yi chan dian chu li wei zhu ,chan dian chu li fang fa bu jin zao cheng le you xiao shu ju de lang fei ,er ju hu shi le ge ce dian shu ju jian de guan lian xing 。you yu duo kong jing TEMcun zai lei xiang gan xing ,tong yi de zhi ti zai xiang lin ce dian shang de fan she hui bo ju you jiao hao xiang guan xing 。yin ci ,dui TEMxin hao ke yi jin hang ge cheng kong jing cheng xiang 。jie jian ge cheng kong jing ju jiao chao sheng cheng xiang ji shu de ji ben sai xiang ,ben wen yin ru “ge cheng kong jing ju jiao shun bian dian ci cheng xiang ji shu ”,di chu yi tao xin de shu ju chu li fang fa ,ji cai yong yan shi xiang guan die jia suan fa ,shi xian bo shu xing cheng he duo ce dian shu ju ju jiao ge cheng 。zai wan cheng bo chang bian huan hou ,yi ce dian wei zhong xin ,xiang lin ce dian xin hao yan shi xiang guan die jia ,jiang chuan tong de chan dian chu li fang shi fa zhan wei duo dian ge cheng fang fa ,zhu dian tui yi 、duo ci fu gai 。you ci da da di gao jie shou xian juan de kong jing chang du he shu ju de xin zao bi ,cong er di gao shun bian dian ci fa de fen bian lv he jie shi jing du 。li yong bu tong ceng zhuang mo xing dui ge cheng kong jing ju jiao shun bian dian ci cheng xiang li lun ji ji fang fa he suan fa jin hang le yan zheng ,jie guo biao ming ,gai fang fa neng gou you xiao yi zhi zao sheng gan rao ,tu chu yi chang ,di gao shun bian dian ci fa dui dian xing jie mian de fen bian neng li 。dui shi ce shu ju fen xi biao ming ,li yong shun bian dian ci chang bo chang bian huan yu ge cheng kong jing ju jiao chu li neng gou shi xian dui di zu kuang ti ou cheng xiang ,dui di zu yi chang ou dian xing jie mian fan ying jiao hao ,yu dian zu lv fan yan duan mian tu xiang bi fen bian lv jiao gao 。
论文参考文献
论文详细介绍
论文作者分别是来自桂林电子科技大学的赵小宇，发表于刊物桂林电子科技大学2019-10-15论文，是一篇关于瞬变电磁论文,虚拟波场论文,预条件正则化共轭梯度法论文,合成孔径聚焦论文,延时相关叠加论文,桂林电子科技大学2019-10-15论文的文章。本文可供学术参考使用，各位学者可以免费参考阅读下载，文章观点不代表本站观点，资料来自桂林电子科技大学2019-10-15论文网站，若本站收录的文献无意侵犯了您的著作版权，请联系我们删除。
标签：瞬变电磁论文; 虚拟波场论文; 预条件正则化共轭梯度法论文; 合成孔径聚焦论文; 延时相关叠加论文; 桂林电子科技大学2019-10-15论文;