中国内陆高原地闪特征的统计分析

利用微秒级时间分辨率的宽带慢天线电场变化仪首次在中国内陆高原地区对雷暴过程中的正、负地闪特征进行了测量和系统分析 ,发现每次雷暴过程中正闪的比例有随总闪频数增大而减少的趋势 ,弱雷暴过程更有利于正地闪的产生。平均来讲 ,正地闪占闪电总数的 16 % ,介于美国夏季雷暴和日本冬季雷暴之间。负地闪闪击间隔的算术平均值和几何平均值分别为 6 4.3ms和 46 .6ms。 5 4%的负地闪有至少一次继后回击强度大于首次回击 ,而且有 2 0 %的继后回击其强度大于首次回击强度。继后回击强度与首次回击强度的比例几何平均值为 0 .46 ,算术平均值为 0 .70 ,平均回击数为 3.76 ,39.8%为单次回击地闪。正地闪的多次回击只占 13.0 % ,且闪击之间的时间间隔也较大 ,算术平均值为 91.7ms。     

四川攀枝花2008年8月31日Ms 5.6地震震源深度的确定

利用四川区域数字地震台网记录,采用滑动时窗相关法识别sPn震相,测定了四川攀枝花2008年8月31日Ms 5.6地震的震源深度.研究结果显示,震源深度为17 km,表明震源位于中上地壳.元谋-绿汁江断裂带上中强地震分布与断裂走向吻合,震源机制解以走滑为主,这些表明此断裂近乎直立.结合此次地震的震源深度,我们推测此断裂可能达到20 km深.     

天山-兴蒙造山带主要钼矿床Re-Os定年和地质意义

天山-兴蒙钼矿带是中亚成矿域的重要组成部分,该成矿带主要呈近东西向分布;本文通过对天山-兴蒙钼矿带4个典型矿床Re-Os同位素精确定年,结合前人区域动力学背景的研究,揭示天山-兴蒙造山带钼矿床的成矿作用主要与岩浆侵入形成的花岗岩热液作用有关,并识别出兴蒙造山带3期岩浆活动、钼成矿作用和构造热事件;Re-Os定年结果揭示出晚古生代铜-钼矿床与俯冲-增生作用有关,三叠纪钼的成矿形成于西伯利亚板块与塔里木-华北克拉通碰撞背景下,而侏罗纪-早白垩世的钼成矿作用与古太平洋板块西向俯冲作用有关。     

粒子群优化BP神经网络的滑坡敏感性评价

滑坡敏感性评价是地质灾害预测预报的关键环节。针对BP神经网络易陷入局部最小值、收敛速度慢等问题,该文以三峡库区秭归县境内为研究区,采用粒子群优化(PSO)算法对BP神经网络的初始权值和阈值进行优化,构建PSO-BP神经网络滑坡敏感性预测模型,实现研究区滑坡敏感性评价。采用受试者工作特征曲线分析模型预测精度,得到PSO-BP神经网络预测精度为0.931,预测结果与实际滑坡总体空间分布具有良好的一致性,且预测能力优于BP神经网络。实验结果表明,PSO-BP神经网络耦合模型在实现滑坡敏感性评价上具有理想的预测精度和良好的适用性。     

皱纹盘鲍肠上皮组织立克次体超微结构与细胞病理学研究

利用电镜技术对患病濒死皱纹盘鲍 (H aliotis Discus hanna Ino)进行病原体检测和病理观察 ,在肠上皮组织中发现大量立克次体。研究表明 ,皱纹盘鲍肠上皮细胞中的立克次体分为增殖型立克次体和静止型立克次体 2种类型。立克次体以皱纹盘鲍肠上皮细胞为感染的靶细胞 ,造成细胞微绒毛全部或部分破坏 ,细胞功能丧失 ,是造成养殖皱纹盘鲍病害发生和死亡的主要病原体。     

Reliability Index of Caisson Breakwaters for Load Variables Correlated

In order to suit the condition that the wave uplift is correlated with the horizontal wave load acting on a vertical breakwater, a generally used method for determining the reliability index β of the breakwater, i.e. the Hasofer-Lind method, is extended in a generalized stochastic space for correlative variables. The computational results for a caisson breakwater indicate that the value of β for the case of correlated variables is obviously smaller than that for the case of independent variables.     

气候变化对内蒙古小叶杨叶芽开放期的影响

利用趋势倾向率等统计分析方法,对内蒙古气候(1961—2006年)和小叶杨叶芽开放期(1981—2006年)的变化趋势进行了分析,并探讨小叶杨叶芽开放期与不同时段的气温、降水、日照的相关性以及气候因子的综合作用。分析发现:内蒙古地区小叶杨叶芽开放期变化趋势表现出强烈的地域差异。小叶杨平均叶芽开放期孪井滩最早,鄂温克最晚,两地相差39 d;各地区小叶杨叶芽开放期的变化趋势基本一致,除额尔古纳呈提前趋势外,其他地区表现出延迟趋势;小叶杨叶芽开放期与春季气温均呈显著负相关,即春季气温升高,小叶杨叶芽开放期提前,与降水和日照的相关性不显著;在日照充足的内蒙古地区气温和降水共同影响着小叶杨叶芽开放期的变化。     

Analysis of the Initial Stage Intracloud Lightning Using the Pulse Location Technique Based on the Fast Electric Field Change

Academy of Sciences,Beijing 100029 2 Lanzhou University,Lanzhou 730000 3 Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences,Lanzhou 730000 4 Nanjing University of Information Science＆Technology,Nanjing 210044
Using both fast and slow electric field change sensors and field mill,multi-station observations on lightning flashes over China inland plateau areas were conducted during the summer of 2004.All of the stations were synchronized by GPS with a time-resolution of±50 ns.Using the different time of arrival（DTOA）and based on the fast electric field change sensor,a lightning radiation location technique was developed.Radiation pulses in the initial stages of five intracloud（IC）lightning discharges which occurred on 20 August were analyzed.The results indicate that the technique developed could effectively locate the lightning radiation sources.Furthermore,the lightning discharges were compared with the Doppler radar data.The results show that the radiation sources were well associated with the storm development.When the storm was at the mature stage with an echo top of about 10.9 km,the radiation sources ranged from 5.2 to 8.3 km above mean sea level;when the storm gradually became weaker,with echo top of about 7.9 km,the radiation sources ranged from 3.0 to 5.9 km.In particular,one of the IC lightning discharges ranged from 3.0 to 4.9 km during the dissipation stage of the storm.The results also indicate that the radiation sources were closely associated with the high reflectivity region（25–50 dBZ）of the storm,which,to some extent,demonstrates the reliability of the location results,thereby showing that multi-station observations of fast electric field change sensors could be a useful tool for monitoring the storm development.Location errors from radiation sources were also compared with the radar data and the results of a simple simulation.It was found that the errors were getting smaller when the radiation sources approached the center of the detection network, and vice versa.Compared with the limited experimental observations,the simulation results were found capable of effectively reflecting the location errors.     

短基线时间差闪电辐射源探测系统和初步定位结果

介绍了一种新型的闪电探测设备———短基线时间差法辐射源定位系统,并选取2002年夏季野外观测实验中的辐射源定位结果,结合电场变化特征分别对两次地闪和云闪进行了分析。结果表明,该系统对地闪先导过程和云闪产生的辐射源能够较好地定位。定位结果的个例分析证实,观测地区的两次云闪放电过程都由起始于云下部负电荷区的负极性击穿引发,然后向上发展到上部正电荷区,通道的发展速度约为1.29×105m·s-1,地闪梯级先导的传播速度约为1.73×105m·s-1。