COMPARISON OF SINGLE-STATION LIGHTNING LOCATION WITH THREE-STATION MEASUREMENTS AND RADAR DATA

A single-station or monostatic lightning detection and ranging system (M-LDARS),that is based on Wait's wave propagation theory and arrival-time differences between sky- and ground-wave atmospherics,has been developed by the University of Science and Technology of China (USTC).Lightning location by the system was compared with a three-station lightning location (TLL) system during July and August 1991 in Beijing,under the support of Chinese Academy of Meteorological Sciences (CAMS).The experimental results show that M-LDARS system can be used to observe direction,distance,intensity and polarity of cloud-to-ground strokes with good confidence for ranges less than about 250 km.90 percent of M-LDARS location points were within radar echoes,i.e.about 90% of the points were inside of the 0 dB isoline or outside,but within 10 km of the 0 dB isopleth.Average direction deviation and relative average deviation of distance between the single- and three-station measurements are respectively 12.8° and 14.1%.     

外加剂对改善镁水泥抗水性能的研究

本文介绍了磷酸盐复合外加剂对镁水泥抗水性能的改善,并初步探讨外加剂对改善镁水泥抗水性能的机制。     

中国速报震级与国际通用震级的初步对比分析

本文主要利用１９８６－１９８７两年速报震级资料，统计分析了中国地震速报台网确定震级的精度，全国各速报台相对中国地震速报台网测定震级的偏差。同时统计分析了中国地震速报台网相对中国地震台临时报告、美国地质调查所震中初定报告ＰＤＥ和国际地震中心ＩＳＣ报告震级的偏差，并对所得结果进行了初步分析。     

陇南中─下三叠统磁性地层划分

根据古地磁测试资料尝试对甘肃南部宕昌县岷江剖面的中－下三叠统浊积岩系进行了磁性地层划分，认为该套地层应属二叠－三叠纪混合极性超时期间的产物，研究区当时的古纬度约为２０°Ｎ。     

重磁界面的一种快速正、反演方法

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。     

中国省级人口分布影响因素的定量分析*

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。     

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

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。     

Pumpspeicherwerke und Hechtbrut—ein Modellversuch

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.     

天津市北部尔王庄地区末次盛冰期下切河谷特征

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。     

Simulating nonequilibrium transport of atrazine through saturated soil

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.