大地电磁法三维共轭梯度反演研究   总被引：12，自引：4，他引：8  

林昌洪  潭捍东  佟拓 《应用地球物理》2008,5(4):314-321

Based on the analysis of the conjugate gradient algorithm, we implement a threedimensional （3D） conjugate gradient inversion algorithm with magnetotelluric impedance data. During the inversion process, the 3D conjugate gradient inversion algorithm doesn＇ t need to compute and store the Jacobian matrix but directly updates the model from the computation of the Jacobian matrix. Requiring only one forward and four pseudo-forward modeling applications per frequency to produce the model update at each iteration, this algorithm efficiently reduces the computation of the inversion. From a trial inversion with synthetic magnetotelluric data, the validity and stability of the 3D conjugate gradient inversion algorithm is verified.  相似文献   

深海柱样粒度分维特征及其古海洋学意义     

章伟艳  殷汝广  张富元  卢冰  陈荣华 《海洋通报》2005,24(1):41-46,55

对南海69柱样粒度数据分析表明,晚更新世以来,粒度在0,2～11um的标度范围内具有分形特征,粒度分维值为1．72～2．02,平均1．84。与同期亚北极B2-9柱地层对比,69柱粒度分维值明显比B2—9柱的高,B2—9柱的粒度在0,2～16um标度范围内具有分形特征,粒度分维值为1.74～1．79,平均1．77。同一柱样不同时期粒度分维值明显不同,南海69柱氧同位素1期(冰后期)为1．88,氧同位素2期(冰期)为1．81,温暖的冰后期粒度分维值高且变化幅度大,寒冷的冰期粒度分维值低且变化幅度小,表明粒度分维值对沉积物的形成环境演化具有良好的指示意义。  相似文献   

Penetration characteristics of VLF wave from atmosphere into lower ionosphere   总被引：1，自引：0，他引：1  

Shufan Zhao  Xuhui Shen  Weiyan Pan  Xuemin Zhang  Li Liao 《地震学报(英文版)》2010,(3):275-281

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Lumped surface and sub‐surface runoff for erosion modeling within a small hilly watershed in northern Vietnam          下载免费PDF全文

Yen Tan Bui  D. Orange  S. M. Visser  Chu Thai Hoanh  M. Laissus  A. Poortinga  Duc Toan Tran  L. Stroosnijder 《水文研究》2014,28(6):2961-2974

Developing models to predict on‐site soil erosion and off‐site sediment transport at the agricultural watershed scale represent an on‐going challenge in research today. This study attempts to simulate the daily discharge and sediment loss using a distributed model that combines surface and sub‐surface runoffs in a small hilly watershed (< 1 km²). The semi‐quantitative model, Predict and Localize Erosion and Runoff (PLER), integrates the Manning–Strickler equation to simulate runoff and the Griffith University Erosion System Template equation to simulate soil detachment, sediment storage and soil loss based on a map resolution of 30 m × 30 m and over a daily time interval. By using a basic input data set and only two calibration coefficients based, respectively, on water velocity and soil detachment, the PLER model is easily applicable to different agricultural scenarios. The results indicate appropriate model performance and a high correlation between measured and predicted data with both Nash–Sutcliffe efficiency (Ef) and correlation coefficient (r²) having values > 0.9. With the simple input data needs, PLER model is a useful tool for daily runoff and soil erosion modeling in small hilly watersheds in humid tropical areas. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Measurement of solid suspension concentration and flow velocity with temperature compensation using a portable ultrasonic device     

Y. J. Huang  C. C. Sung  J. S. Lai  F. Z. Lee  G. W. Hwang  Y. C. Tan 《水文科学杂志》2013,58(3):615-626

Abstract

Ultrasonic spectroscopy is highly suitable for real-time measurement, in particular for dense particle systems. In the present study, a novel measurement device, namely a portable ultrasonic device (PUD), is designed and manufactured for measuring solid suspension concentration and flow velocity simultaneously with respect to the propagation of ultrasound waves in a solid–liquid mixture at different temperatures. A series of experiments were conducted in the laboratory to obtain the ultrasonic attenuation of kaolin and reservoir sediment solutions within a wide range of concentrations (1000–300 000 mg/L) at various temperatures (15–27°C). The resulting data were regressed to establish linear functions of attenuation and temperature for concentration. The experimental data were compared with theoretical simulated results to show the effect of particle size distribution on concentration measurement. The flow meter part of the PUD was verified by a standard-speed carriage in the towing tank. According to experimental tests by PUD, it was demonstrated that the accuracy for concentration in full scale is ±5%, and the accuracy for flow velocity is ±2%. Compared with sampled data, good agreements were also found by employing the PUD for sediment concentration and flow velocity measurements in turbidity currents during typhoon floods in a reservoir, which demonstrates that the PUD is operable and reliable on site.

Editor D. Koutsoyiannis; Associate editor K. Heal

Citation Huang, Y.J., Sung, C.C., Lai, J.S., Lee, F.Z., Hwang, G.W., and Tan, Y.C., 2013. Measurement of solid suspension concentration and flow velocity with temperature compensation using a portable ultrasonic device. Hydrological Sciences Journal, 58 (3), 615–626.  相似文献   

A two‐dimensional inverse model to identify transmissivity in an anisotropic aquifer     

Shih‐Ching Wu  Yih‐Chi Tan  Chu‐Hui Chen  Shien‐Tsung Lin  Kai‐Yuan Ke 《水文研究》2008,22(26):5086-5096

This study suggested a numerical model using the Tabu search algorithm along with the Adjoint State method to identify the hydrogeological characteristics of an anisotropic groundwater aquifer. The Tabu search algorithm was applied to identify the anisotropic transmissivity components to avoid a local optimum. Then, the Adjoint State method was used to calculate the sensitivity of the parameters in order to increase the efficiency of the optimization. For an anisotropic and homogeneous aquifer, results showed that the optimal procedure presented combining the Tabu search algorithm and the Adjoint State method might successfully identify the values of the transmissivity components. If the duration of the pumping test was long enough (12‐h pumping test), the value of the transmissivity components could be optimized with type‐curve, straight‐line, and Tabu search methods, along with the Adjoint State methods. If the duration of the pumping test was short (0·5‐h pumping test), the Tabu search method, along with the Adjoint State method proposed herein, might successfully optimize the transmissivity components. For an anisotropic but heterogeneous aquifer, results showed that the suggested optimal procedure still successfully identified the values of the transmissivity components. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

People On the Move: Rural–Urban Interactions in Sarawak – By Ryoji Soda     

Danny G. Tan 《Singapore journal of tropical geography》2009,30(1):143-144

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自适应重磁对应分析     

范正国  刘前坤  黄旭钊  张洪瑞  周道卿  杨雪  谭林 《吉林大学学报(地球科学版)》2012,(6):1903-1911,1919

采用传统重磁对应分析数据处理方法,计算了单体模型和三体模型条件下重磁异常的相关系数。结果显示:重磁异常中心区域的相关系数绝对值在重磁异常重合时为1,否则小于1(能指示重磁异常是否相关);在远离异常源或无重磁异常地区的相关系数绝对值不论重磁异常是否重合都趋于1(没有实际意义)。鉴于此,笔者提出了自适应重磁对应分析方法,并在晋冀北缘-辽西铁矿成矿带进行了2种方法的对比应用试验。结果表明:在滦南、司家营南部、马城等重磁异常完全重合的地区,2种数据处理方法的处理结果都表明为重磁正相关地区;在新集以东、小马庄西南部、石门东北部等重磁异常不完全重合或根本没有重磁局部异常的地区,传统重磁对应分析数据处理方法的处理结果也显示为正相关地区,自适应重磁对应分析数据处理方法的处理结果没有相关数据点或异常。  相似文献   

Geochemical characteristics and metallogenesis of Carlin-type gold deposits in the Sandu-Danzhai metallogenic zone, Guizhou Province, China     

Baowen Yan  Yong Xia  Zepeng Wang  Qingping Tan  Shourong Wu  Erchuan Fan 《中国地球化学学报》2012,31(3):209-220

Geochemical studies of the Paiting and Miaolong Carlin-type gold deposits in the Sandu-Danzhai metal-logenic zone,Guizhou Province,have shown that the mineralized-altered rocks show LREE-enrichment patterns,generally displaying negative Eu anomalies(δEu=0.51?0.97) and unobvious negative Ce anomalies(δCe=0.86?0.99).Calcite and fluorite in relation with metallogenesis show MREE-enrichment patterns,generally displaying rather weak negative Eu anomalies(δEu=0.74?0.93) and weak negative Ce(δCe=0.70?0.98) anomalies.The δ13CPDB values of carbon in calcite are-1.61‰?-5.82‰,the δ18OSMOW values of oxygen are 13.97‰?19.24‰,and the δ34SCDT values of sulfur in stibnite are 17.72‰?21.68‰.In regard to δD and δ18O,ore-forming fluids pos-sess the characteristics of metamorphic water.The process of metallogenesis of the Carlin-type gold deposits is con-trolled by the Yanshanian tectonic activities.The Yanshanian movement promoted the migration and mobilization of metamorphic fluids in the extensively developed medium-to high-grade metamorphic rocks in this region,carrying primarily enriched gold and associated elements such as Hg,As,and Sb in the Sinian metamorphosed black shales and Lower Cambrian black shales.The ore-forming fluids found their way into a suitable metallogenic environment along the fault zone,followed by gold precipitation to form gold deposits.  相似文献   

氯化物解聚快速测定铁矿石中二氧化硅   总被引：1，自引：0，他引：1  

赵玲  李胜生  冯永明  董磊磊  谭星洁 《安徽地质》2012,(4):305-307

采用NaOH熔融、蒸馏水浸取、盐酸中和并酸化、氟化物解聚和钼酸铵显色测定铁矿石中的二氧化硅。本方法的检出限为0．10％。本实验以测定了国家一级铁矿标样来验证方法的准确度和精密度,测定结果与标准值相符,且测定12次的相对标准偏差（RSD）均小于10％。  相似文献