在大地电磁二维Occam反演中求取拉格朗日乘子方法改进   总被引：1，自引：0，他引：1  

朴英哲  李桐林  刘永亮 《吉林大学学报(地球科学版)》2014,44(2):660-667

Occam反演具有可靠性和加上各种先验信息可行性的优点,但是因为求取拉格朗日乘子需要很长时间,所以前人提出了几个直接选取方法。笔者改进了二维大地电磁测深Occam反演中求取拉格朗日乘子的方法。在搜索过程中加上观测数据拟合差与其期望值的比较。这样,在Occam反演的拟合差下降阶段的最后迭代和模型光滑阶段,能够排除多余的正演计算。这种改进对反演结果没有影响,但却使得反演速度加快并且更符合于Occam思想。根据模型实验和野外数据处理,可以减少正演次数20%~50%。  相似文献   

松潘-阿坝地区深部电性特征   总被引：3，自引：0，他引：3  

陈高  吴健生  于鹏 《地球科学》2006,31(6):857-860,878

针对青藏高原东部特殊的“三角形”区域——松潘-阿坝地区,通过两条测线的MT资料分析和反演,对其深部电性特征进行了揭示,发现松潘-阿坝区中深层构造较为稳定,层状特点明显,地下电性横向变化小,具有稳定地块的特点.这里存在壳内低阻层,厚度近10~20km;深部(岩石圈地幔内部)的电性结构也有两种类型:高阻异常区和具有幔内低阻层的次高阻异常区,全区岩石圈厚度在120km左右,其四周由深断裂与邻区接触.该区深部电性特征不同于龙门山隆起的电性结构,也不同于西秦岭构造带,后者具有高阻基底,岩石圈厚度或更薄或加厚.  相似文献   

地面电磁探测(SEP)系统对比试验——内蒙曹四夭钼矿   总被引：4，自引：3，他引：1       下载免费PDF全文

底青云  许诚  付长民  王中兴  张文秀  安志国  王若 《地球物理学报》2015,58(8):2654-2663

为了检验自主研制的地面电磁探测(SEP)系统各组成部分在实际勘查中的性能与可靠性,以及整体系统的野外实际工作能力,在内蒙古乌兰察布市兴和县的曹四夭钼矿开展了SEP不同类型磁传感器之间以及SEP整套系统与国外商业仪器系统的全面对比试验.试验采用多种方案,分别进行了高温超导磁传感器和感应式磁传感器之间的性能对比试验;磁通门磁传感器和感应式磁传感器之间的性能对比试验;SEP发射机与GGT-30发射机、TXU-30发射机的发射性能对比试验;SEP系统与V8、GDP-32II等国际先进仪器的CSAMT法综合对比试验;以及SEP系统和V8系统的MT法对比试验.本文对试验结果进行了分析,表明自主研制的SEP系统已经基本达到甚至优于国外同类产品的性能,能够很好地胜任野外实际勘查工作.  相似文献   

用TEM反演法进行MT静位移的识别和校正   总被引：6，自引：0，他引：6  

杨长福  林长佑 《地球科学》2001,26(6):609-614

对瞬变电磁(TEM)资料进行反演时, 采用观测磁场而不用视电阻率, 避免了由于TEM视电阻率定义而引起的误差, 并且由源象磁场和观测磁场之间的拟合进行反演使反演结果受非均匀性影响较小; 将反演结果构置出地电模型, 计算出它的MT曲线作为静位移校正的参考曲线, 使它用于MT静位移校正更为可靠, 同时也解决了两种电磁资料从时间域到频率域的转换问题.由此实现用TEM反演的方法进行MT静位移的识别和校正.实例表明, 这种方法对MT静位移的识别和校正十分有效.   相似文献   

Effects of mercuric chloride on antioxidant system and DNA integrity of the crab Charybdis japonica     

Hongxia Zhang  Luqing Pan  Jingjing Miao  Chaoqun Xu 《中国海洋大学学报(英文版)》2009,8(4):416-424

Mercury (Hg) is one of the commonly encountered heavy metals, which is widespread in inshore sediments of China. In order to investigate the toxicity of Hg on marine invertebrates, we studied the effects of the divalent mercuricion (Hg²⁺) (at two final concentrations of 0.0025 and 0.0050 mg L⁻¹, prepared with HgCl₂) on metallothionein (MT) content, DNA integrity (DNA strand breaks) and catalase (CAT) in the gills and hepatopancreas, antioxidant enzyme activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), in the hemolymph, gills and hepatopancreas of the portunid crab Charybdis japonica for an experiment period up to 15 d. The results indicated that MT was significantly induced after 3 d, with a positive correlation with Hg²⁺ dose and time in the hepatopancreas and a negative correlation with Hg²⁺ dose and time in the gills. While CAT in the hemolymph was not detected, it increased in the hepatopancreas during the entire experiment; SOD and GPx in the three tissues were stimulated after 12 h, both attained peak value and then reduced during the experimental period. Meanwhile, DNA strand breaks were all induced significantly after 12 h. These results suggested the detoxification strategies against Hg²⁺ in three tissues of C. japonica.  相似文献   

Structural imaging of Mesozoic sediments of Kachchh,India, and their hydrocarbon prospects     

Dhananjai Pandey  Satish Singh  Martin Sinha  Lucy MacGregor 《Marine and Petroleum Geology》2009

Travel-time modelling of first and second arrivals has been used to produce P-wave velocity models of the shallow sub-surface structure of Kachchh, India, using new wide-angle reflection/refraction profiles. Results obtained from the 2-D tomographic modelling have also been corroborated with magnetotelluric and borehole data within the proximity of these profiles. Based on multiple geophysical data, a composite sub-surface model is presented in this article. The prominent features of the model include the presence of more than 3 km thick Mesozoic sediments residing above the Precambrian basement. Its correlation with available lithological knowledge shows that the Mesozoic rocks have been deposited from early Triassic to late Cretaceous until the eruption of the Deccan Flood basalts at the Cretaceous-Tertiary boundary. The new results suggest that the Mesozoic rocks of Kachchh can be sub-divided in two major parts which correspond to late and early Mesozoic deposits respectively. The sub-surface models successfully demarcate the regional variations in the basaltic layer across the region and show maximum thickness of 1.2 km. The modelling results also exhibit that the Precambrian basement in this region varies between 4 and 6 km depth. The new data provide a much clearer picture than was hitherto available of the entire sedimentary succession in the basins that underlie the Kachchh region. They show a significant variability in thickness of the various sedimentary layers, and in particular illustrate a marked topographic irregularity at the base of the sedimentary succession.  相似文献   

天津蓟县高于庄组微亮晶(MT)碳酸盐岩的沉积环境及成因探讨   总被引：2，自引：0，他引：2  

王德海  孟祥化  郭峰  任国选  葛铭 《吉林大学学报(地球科学版)》2009,39(6)

微亮晶(MT)碳酸盐岩是发育在中、新元古代的特殊碳酸盐岩,全球分布广泛,MT构造由纯净、等粒的微亮晶方解石组成.天津蓟县中元古界高于庄组发育丰富的MT碳酸盐岩,并且在浊积岩中发现新的MT类型.详测高于庄组剖面,通过米级旋回类型划分、沉积环境、费希尔图解、扫描电镜、电子探针研究,并结合海平面变化、Sr和C同位素研究表明:原生MT构造主要发育在碳酸盐岩台地潮下型,深水非对称型米级旋回中上部的泥晶灰岩、细粉屑灰岩、钙质泥岩以及浊积岩球体的核心部位;MT碳酸盐岩主要发育在米级旋回海平面上升的高水位时期,~(87)Sr/~(86)Sr 值较低(小于0.709 67),δ~(13)C值为(0±1)‰的古海水环境中.  相似文献   

阿尔山火山区地壳上地幔电性结构初探   总被引：18，自引：7，他引：11       下载免费PDF全文

汤吉  王继军  陈小斌  赵国泽  詹燕 《地球物理学报》2005,48(1):196-202

在阿尔山活火山区一条北北西向测线上进行了7个大地电磁测深点的观测。2-D解释结果表明,研究区内新、老两条火山带可能存在通往深部的岩浆通道。其中,新发现的活火山带地下在10~12km还保持着较高的热状态,很可能富含流体,在30~50km处可能是地幔向上的供热通道;而老火山带30km以上可能存在一个正在冷却的岩浆通道,两条火山条带的深部可能是同源的。  相似文献   

Assessment of digital camera-derived vegetation indices in quantitative monitoring of seasonal rice growth   总被引：4，自引：0，他引：4  

Toshihiro Sakamoto  Michio Shibayama  Akihiko Kimura  Eiji Takada 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(6):872-882

A commercially available digital camera can be used in a low-cost automatic observation system for monitoring crop growth change in open-air fields. We developed a prototype Crop Phenology Recording System (CPRS) for monitoring rice growth, but the ready-made waterproof cases that we used produced shadows on the images. After modifying the waterproof cases, we repeated the fixed-point camera observations to clarify questions regarding digital camera-derived vegetation indices (VIs), namely, the visible atmospherically resistant index (VARI) based on daytime normal color images (RGB image) and the nighttime relative brightness index (NRBI_NIR) based on nighttime near infrared (NIR) images. We also took frequent measurements of agronomic data such as plant length, leaf area index (LAI), and aboveground dry matter weight to gain a detailed understanding of the temporal relationship between the VIs and the biophysical parameters of rice. In addition, we conducted another nighttime outdoor experiment to establish the link between NRBI_NIR and camera-to-object distance. The study produced the following findings. (1) The customized waterproof cases succeeded in preventing large shadows from being cast, especially on nighttime images, and it was confirmed that the brightness of the nighttime NIR images had spatial heterogeneity when a point light source (flashlight) was used, in contrast to the daytime RGB images. (2) The additional experiment using a forklift showed that both the ISO sensitivity and the calibrated digital number of the NIR (cDN_NIR) had significant effects on the sensitivity of NRBI_NIR to the camera-to-object distance. (3) Detailed measurements of a reproductive stem were collected to investigate the connection between the morphological feature change caused by the panicle sagging process and the downtrend in NRBI_NIR during the reproductive stages. However, these agronomic data were not completely in accord with NRBI_NIR in terms of the temporal pattern. (4) The time-series data for the LAI, plant length, and aboveground dry matter weight could be well approximated by a sigmoid curve based on NRBI_NIR and VARI. The results confirmed that NRBI_NIR was more sensitive to all of the agronomic data for overall season, including the early reproductive stages. VARI had an especially high correlation with LAI, unless yellow panicles appeared in the field of view.  相似文献   

大兴安岭西北部中新生代盆地群基底电性分带特征研究   总被引：8，自引：5，他引：3       下载免费PDF全文

刘财  杨宝俊  王兆国  刘洋  王典  冯晅  鹿琪  王世煜 《地球物理学报》2011,54(2):415-421

位于大兴安岭西北部的中新生代盆地群(海拉尔、根河、漠河),其构造受到大兴安岭断裂、德尔布干断裂的控制,西北方向的蒙古-鄂霍茨克缝合带、南部西拉木伦河-延吉缝合带甚至更远的西太平洋板块运动、印度板块运动以及黑龙江中西部微板块间拼合等区域构造应力场叠加作用在该盆地群基底产生了复杂的深部构造特征.本文利用沿盆地群实施的4条(...  相似文献