重磁界面的一种快速正、反演方法   总被引：2，自引：1，他引：2  

李燕  於庆利  余钦范 《物探与化探》1993,17(6):435-440

重磁界面的正反演方法研究是地球物理解释方法中的重要课题。本文在前人研究Raker反演方法的基础上采用了一种增强反演稳定性的快速正反演方法,并较好地解决了稳定因子中参数选择问题。本文还对该方法的收敛性及影响反演效果的诸因素加以详细讨论。理论模型及应用实例说明该方法是一种令人满意的快速正反演方法。  相似文献   

中国省级人口分布影响因素的定量分析^*   总被引：3，自引：1，他引：3  

孟向京  贾绍凤 《地理研究》1993,12(3):56-63

本文主要用1987年的数据,对影响省级人口密度的31种因素指标进口了相关和回归分析,建立了各种因素对人口密度的回归公式。作者引进了两个新的经济指标:单位国土面积粮食产量和国民收入。分析表明这两个指标比其他经济指标与人口密度的相关更紧密,自然因素尤其是海拔影响最大,其次是经济因素。  相似文献   

四川峨眉麦地坪剖面震旦系—寒武系界线的新认识及有关化石群的记述   总被引：6，自引：1，他引：6       下载免费PDF全文

陈孟莪 《地质科学》1982,(3):253-263

研究剖面位于峨眉山东坡,距峨眉县城约14公里。峨眉山区在大地构造上处于川滇南北向构造带的东侧——峨眉山块断带。震旦系-寒武系出露在蛾眉山背斜两翼,构造简单,地层连续,化石丰富。此剖面先后经过多人研究。  相似文献   

Pumpspeicherwerke und Hechtbrut—ein Modellversuch     

W. Geiger  H. J. Meng dipl. Natw. ETH  Chr. Ruhlé  dipl. Forsting. ETH  Chr Ruhlé 《Aquatic Sciences - Research Across Boundaries》1975,37(2):225-234

The effects of periodic, simulated water level fluctuations on northern pike fry produced by pumped-storage operations were examined. Daily fluctuations of 10 cm caused a significant increase in the daily mortality rate. Waves reduced the detrimental effect of water level lfuctuations, at least during the adhesive phase of fry.  相似文献   

天津市北部尔王庄地区末次盛冰期下切河谷特征          下载免费PDF全文

樊航宇  张树栋  黄猛  张晓飞  周长红 《地质找矿论丛》2020,35(4):447-453

渤海湾西岸尔王庄地区钻孔岩芯、微体古生物、孢粉及¹⁴C测年等资料及联合地质剖面研究结果表明，末次盛冰期全球海平面下降使该地区形成下切河谷，冰后期海平面迅速上升引发的海侵造成古河谷的充填，依次形成河床相、河漫滩―河口湾相和三角洲相，与相邻的滦河扇三角洲下切河谷有差异，该下切河谷受海河水系控制，流向大致与古潮白河一致。其演化过程受海平面变化、构造运动和古气候等因素影响，经历了末次盛冰期深切、15~7 ka BP海侵期间河床相及河漫滩―河口湾相的充填和之后海退形成的三角洲相埋藏等三个阶段。  相似文献   

Distribution and sources of polynuclear aromatic hydrocarbons in Mangrove surficial sediments of Deep Bay, China   总被引：12，自引：0，他引：12  

Zhang J  Cai L  Yuan D  Chen M 《Marine pollution bulletin》2004,49(5-6):479-486

Twelve sediment samples collected from three transects of mangrove swamp of Deep Bay, Shenzhen, China, were determined for polynuclear aromatic hydrocarbons (PAHs). The total PAHs concentrations ranged from 237 to 726 ng g(-1) dry weight, and showed strong correlation with total organic carbon (TOC), clay content and Pb concentrations. The highest PAHs concentrations were found in the samples from mangrove sediments. Overall, PAHs in Deep Bay sediment were lower than those in other developed areas. The biological effect due to PAHs alone in Deep Bay is expected to be low, based on the comparisons of individual and total PAHs concentrations determined in the sediment with those in USEPA sediment quality guidelines. Four and five-ring compounds dominated the PAHs composition pattern profiles. Principal component analysis (PCA) was applied to further investigate the source of PAHs. The PAH sources of Deep Bay mangrove swamp were suggested to be primarily combustion of fossil fuel, especially leaded-gasoline exhaust.  相似文献   

Simulating nonequilibrium transport of atrazine through saturated soil   总被引：5，自引：0，他引：5  

Mao M  Ren L 《Ground water》2004,42(4):500-508

Atrazine, an herbicide widely used for selective control of grassy weeds in the fields where maize is grown, is a potential ground water contaminant in China and, consequently, there is interest in predicting its mobility in agricultural soils. In this study, we determined the nonequilibrium transport characteristics of atrazine in Shahe soil (Beijing sandy loam) using the advection-dispersion equation, and using a sensitivity analysis, we evaluated the contribution of the uncertainty in a given input parameter to the overall uncertainty in model results. The asymmetrical shape and tailing of the atrazine breakthrough curve (BTC) showed that atrazine was subject to nonequilibrium transport. The observed atrazine BTC was best fitted by the chemical nonequilibrium model with a nonlinear least-squares optimization approach. Results from the sensitivity analysis indicated that the retardation factor was the most sensitive parameter. Considering the reliability of the estimated parameters, the best fit to the atrazine BTC was obtained by fixing the retardation factor based on the linear distribution coefficient, and by calculating the dispersion coefficient from the bromide BTC and the average pore water velocity from the measured data; nonequilibrium parameters were the only unknown parameters that were optimized. Model verification procedures were based on best-fit parameters optimized from one soil column experiment and applied to simulate the transport of atrazine in the duplicate experiment. The results showed there was good agreement between measured and simulated concentrations for atrazine leaching in the soil column.  相似文献   

A semi-empirical formula for evaluating residual strain of soils under earthquake loading     

袁晓铭  孟上九  孙锐 《地震工程与工程振动(英文版)》2003,2(2):307-313

A new semi-empirical formula for evaluating the residual strain of soils under earthquake loading is presented in this paper based on the incremental method and the increment model proposed by the authors. When the incident loading is uniform, the results calculated by the new formula are nearly the same as those by the existing formula. For excitation of the random earthquake loading, the results calculated by the new formula are compared to the results obtained by dynamic triaxial tests. The dynamic triaxial tests had been performed considering different seismic waves, confining stresses,consolidation ratios, and types of cohesive soils. The comparison between the calculated and tested results indicate that the presented formula can efficiently and practically describe the time-dependent process of the soil residual strains under actual seismic loads.  相似文献   

Seismic waves in a layered half-space from an arbitrary buried source     

MENG Fanshun  WANG Zaishan  LI JianjunCollege of Marine Geosdence  Ocean University of China  Qingdao  P.R.ChinaNo. Petrolum-mining Plant  Da Qing Petroleum Administration  Daqing  P.R.China 《中国海洋大学学报(英文版)》2003,2(2):201-206

In this paper, a transfer matrix and a three-dimensional dynamic response of a layered half-space to an arbitrary buried source are derived with the aid of a technique which combines the Laplace and two-dimensional Fourier transforms in a rectangular coordinate system. This method is clear in concept, and the corresponding formulas given in the paper are simple and convenient for marine seismic prospecting and other fields' applications. An example is presented and the calculated results are in good agreement with those of the finite element method (FEM).  相似文献   

天气雷达数字化终端及其应用软件     

张晰莹张礼宝  官福顺安晓存 孟焕生 《气象科技》2004,32(4):297-299

为解决雷达数据采集、实时显示、数据存储、资料处理自动化等问题，进行了天气雷达数字化终端和应用软件技术的研究和开发。改变了711B-1雷达数据存储、分析自动化程度低的状况。增加和丰富了雷达二次产品，使雷达资料得到了充分的分析和应用，提高了雷达对天气的监测能力。增加了对冰雹、暴雨等强对流天气的预警功能、人工增雨效果检验等功能。  相似文献