基于变分模态分解算法的探地雷达信号去噪研究   总被引：1，自引：0，他引：1  

冉利民  李健伟  杜娟  程思远  宋二乔  刘四新 《世界地质》2022,(1):198-207

探地雷达信号属于非平稳信号,容易受到干扰噪声影响导致探测能力降低.为了消除雷达信号的噪声,经验模态分解(EMD)、总体经验模态分解(EEMD)和完全总体经验模态分解(CEEMD)等方法被应用到雷达数据处理中.EMD虽然不断被改进,但仍存在一些不足,例如容易受到噪声干扰,存在模态混叠现象,依赖经验性等问题.因此笔者采用变...  相似文献   

A nonlinear modeling and forecasting system of earth fractures based on coupling of artificial neural network and geographical information system—exemplified by earth fractures in Yuci City,Shanxi, China     

Qiang?WuEmail author  Siyuan?Ye  Xiong?Wu  Peipei?Chen 《Environmental Geology》2003,45(1):124-131

Earth fracturing or fissuring is a natural phenomenon and a major geohazard in many countries. The factors that cause the earth to fracture were analyzed in Yuci City, in Shanxi Province of China using the geographical information system (GIS). A nonlinear simulation and assessment model of earth fracturing was established using the artificial neural network (ANN) technology to simulate the structure and function of the neural network (NN) of the human brain with engineering technology. The developed nonlinear modeling and forecasting system was used to assess and forecast the earth fracture hazard in Yuci City. The results of this study provided useful and essential information for scientific policy-making in the areas of city planning, environmental protection, and land development.  相似文献   

第二代小波变换及其在地震信号去噪中的应用   总被引：12，自引：0，他引：12  

曹思远  陈香朋 《应用地球物理》2005,2(2):70-74

本文讨论了第二代小波变换的基本原理和变换过程，并将第二代小波变换引入到地震资料去噪处理中，基于提升法的小波变换是一种柔性的小波构造方法，它使用线性、非线性或空间变化的预测和更新算子，并能确保变换的可逆性。通过对模拟数据和实际资料的处理，证明了的它对地震信号去噪具有很好的效果。离散信号的小波去噪可分为三步：小波分解，系数缩减（切除噪声部分），信号重建。目前常用的小波去噪的方法有硬阈值法和软阈值法，这里采用软阈值法去噪。本文的提升变换采用的是Deslauriers-Dubuc（4，2）小波，基于以上变换方法，分别对含噪的模拟数据及实际地震数据进行3级可逆提升变换，对每一级上的细节信号按上述的软域值法进行处理，削减小波系数中的噪声部分，从而实现了信号去噪，结果证明去除随机噪声的效果是令人满意的。  相似文献   

地表基质钻探取样技术方法与应用研究     

苏兴涛  冉灵杰  祝强  冯跃文  张永兴  张思源  孙小艳 《地质论评》2023,69(3):2023030013-2023030013

地表基质取样是开展地表基质层调查必不可少的工作环节,笔者等在浅地表层钻探技术的基础上,结合浅覆盖区矿产勘查、地球化学勘查、区域地质填图、环境调查、工程勘查、考古调查等领域钻探技术应用现状,根据不同地表景观及基质类型条件下的钻探取样需求,梳理了岩石、砾质、土质、泥质等地表基质钻探取样技术要点,研发了电动背包式钻机、Ф60/40mm单管冲击钻进、Ф50mm双管冲击钻进、Ф208mm中空螺旋钻进等取样器具及配套钻进工艺,在北京、内蒙古巴彦淖尔、浙江宁波、西藏那曲等地区开展了野外试验应用,通过获取满足要求的样品,很好的揭示了地层信息及物质组成,进一步在实践中提出了不同种类地表基质钻探取样技术方法,为建立自然资源调查监测体系及地表基质层调查工作提供钻探技术支撑。  相似文献   

山东莱芜垂阳矽卡岩型铁矿尾矿中关键金属钴综合利用评价探讨     

段壮  高继雷  马明  冯启伟  李春稼  李思远  李勇  林鲁军  付燕刚  高健翁  郝泽江  李岩 《地质论评》2023,69(6):2023060002-2023060002

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房山贾峪口土洞崩塌危岩带特征及稳定性分析     

赵晨曦  刘明坤  柴利杰  陈柘舟  杨艳锋  刘建凯  常思源 《城市地质》2018,(1):43-47

贾峪口土洞崩塌灾害隐患点位于房山区佛子庄乡贾峪口村北侧,坡顶处存在两条近东西走向的危岩带,坡顶及坡面处植被发育较好,坡顶处未发现明显后缘裂缝,整体稳定性较好,但危岩带内大面积基岩裸露,受雨水冲刷及差异风化等作用影响,表面较为破碎,呈块状、碎裂状,岩腔、裂隙发育。通过勘查掌握了该危岩带及危岩体的基本特征,分析了其主要破坏方式及危岩的运动特征,并对其稳定性进行了定性分析与定量计算。结果表明,危岩带及危岩体在暴雨、地震等工况条件下处于不稳定状态,具有发生崩塌灾害的隐患。针对危岩带的特点,提出危岩清削+主动防护网+被动防护网的治理措施,较为有效地解除了该区域的安全隐患。  相似文献   

悬挂式阻水帷幕地下水控制方法探讨——以北京地铁8号线永定门外站为例     

张志林  马涛  王秀丽  刘思源 《城市地质》2015,(2)

以北京地铁8号线永定门外站为例,提出悬挂式帷幕阻水条件下基坑排水量计算方法以及悬挂式帷幕阻水中存在的问题。介绍了3种结合悬挂式帷幕采取的封底阻水措施,即水下灌注混凝土封底,深孔注浆封底以及超高压旋喷桩封底,并分别探讨了其优缺点。提出了悬挂式帷幕阻水结合基坑底部封底阻水的最佳建议方案,以达到有效节约地下水资源、降低工程施工难度和工程造价之目的。  相似文献   

Late Quaternary strata and carbon burial records in the Yellow River delta,China     

Zhao  Guangming  Ye  Siyuan  Li  Guangxue  Ding  Xigui  Yuan  Hongming 《中国海洋大学学报(英文版)》2015,14(3):446-456

Sediment carbon sequestration plays an essential role in mitigating atmospheric CO2 increases and the subsequently global greenhouse effect. To clarify the late Quaternary strata and carbon burial records in Yellow River delta(YRD), detailed analysis of benthic foraminifera, total carbon(TC), organic carbon(Corg), sedimentary characteristics and moisture contents of sediments, was performed on core ZK3, 30.3 m in length and obtained from YRD in 2007. Eight depositional units(designated U1-U8 in ascending order) were identified. A comprehensive analysis method of historical geography and sedimentary geology was used to determine the precise depositional ages of the modern Yellow River delta(MYRD), from which pre-MYRD ages were deduced. The results indicates that the maximum burial rates of TC, inorganic carbon(IC) and Corg occurred in the delta front(U5), and the minimum in the shallow sea(U3). Remarkable high sedimentation rates in the MYRD are responsible for burial efficiency of carbon, with an average rate of Corg burial reaching 2087±251 g(m2 yr)-1, and that of IC reaching 13741±808 g(m2 yr)-1, which are much higher than those of other regions with high contents of Corg. Therefore, YRD has a significant burial efficiency for carbon sequestration.  相似文献   

2016年梅雨期间长江中下游强降水与对流层上层斜压波包的关系   总被引：3，自引：0，他引：3  

叶德超  管兆勇  孙思远  李鑫  夏阳 《气象学报》2019,77(1):73-83

2016年6—7月,长江中下游地区发生了自1998年以来最严重的强降水事件,造成了重大的经济损失。利用NCEP/NCAR再分析资料和中国2479站逐月及逐日降水资料,研究了2016年梅雨期间长江中下游地区降水与欧亚大陆对流层上层斜压波包活动的关系,并诊断了两者之间的信息流向。结果表明,梅雨期间的高频斜压波动具有明显的下游频散效应。波动起源于黑海,沿西北—东南方向于3—4 d后传至长江中下游地区。斜压波包为长江中下游地区强降水的发生提供了必要的能量。波作用通量矢量的分布表明,梅雨期间逐日均有来自西风带上游的扰动能量向长江中下游流域传播。而梅雨期间降水与斜压波包的信息流关系表明,二者之间存在信息传递。因此,3—4 d并源于黑海附近的斜压波包活动是2016年长江中下游梅雨期间异常降水的成因。这些结果为深刻认识长江中下游地区强降水事件发生的成因和有效预测提供了线索。   相似文献   

Applying Anomaly-based Weather Analysis to the Prediction of Low Visibility Associated with the Coastal Fog at Ningbo-Zhoushan Port in East China     

Weihong QIAN  Jeremy Cheuk-Hin LEUNG  Youli CHEN  Siyuan HUANG 《大气科学进展》2019,36(10):1060-1077

Low visibility episodes (visibility < 1000 m) were studied by applying the anomaly-based weather analysis method. A regional episode of low visibility associated with a coastal fog that occurred from 27 to 28 January 2016 over Ningbo-Zhoushan Port, Zhejiang Province, East China, was first examined. Some basic features from the anomalous weather analysis for this case were identified: (1) the process of low visibility mainly caused by coastal fog was a direct response to anomalous temperature inversion in the lower troposphere, with a warm center around the 925 hPa level, which was formed by a positive geopotential height (GPH) anomaly in the upper troposphere and a negative GPH anomaly near the surface; (2) the positive humidity anomaly was conducive to the formation of coastal fog and rain; (3) regional coastal fog formed at the moment when the southwesterly wind anomalies transferred to northeasterly wind anomalies. Other cases confirmed that the low visibility associated with coastal fog depends upon low-level inversion, a positive humidity anomaly, and a change of wind anomalies from southwesterly to northeasterly, rain and stratus cloud amount. The correlation coefficients of six-hourly inversion, 850?925-hPa-averaged temperature, GPH and humidity anomalies against visibility are ?0.31, 0.40 and ?0.48, respectively, reaching the 99% confidence level in the first half-years of 2015 and 2016. By applying the anomaly-based weather analysis method to medium-range model output products, such as ensemble prediction systems, the anomalous temperature?pressure pattern and humidity?wind pattern can be used to predict the process of low visibility associated with coastal fog at several days in advance.  相似文献