液体闪烁计数技术测氡在铀矿勘查中的应用研究     

邓小卫  王国庆  李洪璧  蔺志璧  贺建国 《铀矿地质》2007,23(1):43-48

在火山岩、花岗岩地区和中新生代盆地铀矿勘查中进行了大量的液体闪烁测氡工作，发现该方法探测效率高、抗干扰能力强、重复性好、异常清晰，取得了较好的地质找矿效果，证实了该方法的有效性和可行性。  相似文献   

GDX-502树脂富集高效液相色谱法测定地表水中酚类化合物   总被引：2，自引：2，他引：2  

何淼  饶竹  苏劲  黄毅 《岩矿测试》2007,26(2):101-104

采用自制GDX-502固相萃取小柱萃取水中苯酚、对硝基酚、间甲酚、2，4-二氯酚、2，4，6-三氯酚、五氯酚等6种酚类化合物，以乙腈作为洗脱剂，选择280nm和290nm双波长紫外高效液相色谱进行检测。结果表明，方法检出限为0．01-0．05mg／L，IL水的平均加标回收率为82．5％-95．0％，精密度（RSD，n=7）为3．6％-9．2％。方法用于实际地表水中痕量酚类化合物的检测，操作简单，有机溶剂用量少，分析效率高；萃取小柱可多次重复使用，分析成本低。  相似文献   

1975年8月河南省特大暴雨雨强极值的重新估算   总被引：1，自引：0，他引：1  

王兴荣  高守亭 《热带气象学报》2007,23(2):196-200

通过对云中气载液态水含量以及水汽和气载液态水之间的平衡方程的讨论,建立了改进的可降水量Ia公式。按照改进的公式,重新估算了1975年8月河南省特大暴雨7日20时雨强。结果表明,分别以遂平气象站记录的8 m/s和按物象估算的12 m/s地面风速为基础的改进的板桥水库附近8月7日20时雨强估算值Iae1=75.0 mm/h和Iae1=95.8 mm/h很接近实际的雨强极值Ioe=99.7 mm/h。  相似文献   

Numerical simulation of NAPL flow in the subsurface     

L.K. Kuiper  T.K. Illangasekare 《Computational Geosciences》1998,2(3):171-189

A three-dimensional, three-phase numerical model is presented for simulating the movement of immiscible fluids, including nonaqueous-phase liquids (NAPLs), through porous media. The model is designed to simulate soil flume experiments and for practical application to a wide variety of contamination scenarios involving light or dense NAPLs in heterogeneous subsurface systems. The model is derived for the three-phase flow of water, NAPL, and air in porous media. The basic governing equations are based upon the mass conservation of the constitutents within the phases. The descretization chosen to transform the governing equations into the approximating equations, although logically regular, is very general. The approximating equations are a set of simultaneous coupled nonlinear equations which are solved by the Newton-Raphson method. The linear system solutions needed for the Newton-Raphson method are obtained using a matrix of preconditioner/accelerator iterative methods. Because of the special way the governing equations are implemented, the model is capable of simulating many of the phenomena considered necessary for the sucessful simulation of field problems including entry pressure phenomena, entrapment, and preferential flow paths. The model is verified by comparing it with several exact analytic test solutions and three soil flume experiments involving the introduction and movement of light nonaqueous-phase liquid (LNAPL) or dense nonaqueous-phase liquid (DNAPL) in heterogeneous sand containing a watertable. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

NUMERICAL STUDY OF REMOTE SENSING OF CLOUD LIQUID WATER CONTENT BY SPACE-BORNE COMBINED RADAR-RADIOMETER   总被引：1，自引：0，他引：1  

刘锦丽  张凌  陈洪滨  吕达仁 《Acta Meteorologica Sinica》1998,(4)

A retrieval method of microwave(MW)space-borne remote sensing of cloud liquid watercontent by the combined radar-radiometer is suggested.A three-layer cloud model is chosen torepresent the typical stratified precipitating cloud.The retrieval method mainly follows ourpreviously suggested scheme with some modifications.Numerical comparative study shows that inspace-borne remote sensing of cloud liquid water content by the combined method is much betterthan by radar only;Also the retrieval accuracy of cloud liquid water content may be improvedwhen using the three-layer cloud model in the combined method.  相似文献   

基于TC35的远程温度监测报警系统     

刘玟宏  王海江  宋静  倪进宝 《成都信息工程学院学报》2015,30(2)

针对日常生活中因对温度变化的忽视引起的各种问题,提出一种对温度进行远程监测并短信通知用户的系统,以达到向用户进行温度报警的目的.系统主要由STC89C52单片机,液晶显示器1602,温度传感器DS18B20,TC35模块4大部分构成,首先通过温度传感器DS18B20采集当前环境温度,然后利用液晶显示器1602将当前温度显示出来,与此同时单片机判断当前温度值,当前温度超过温度上限值时,单片机控制GSM模块向指定手机号发送一条短信.结果显示,当温度超过设定温度时,指定手机会收到一条报警短信,提醒用户当前的温度超过了温度上限.通过与传统的温度检测系统作对比,系统能够得到较准确的温度检测值其测温误差能够控制在0.4以下,并且通过发送短信来对温度进行远程实时监测.  相似文献   

闪电和固、液态降水关系差异的数值模拟     

郭凤霞  吴鑫  梁梦雪  江涛  陆干沂 《大气科学》2015,39(6):1204-1214

为了进一步认识闪电和固、液态降水的关系,本文利用三维雷暴云动力-电耦合数值模式,通过设置敏感性试验组,模拟了一次雷暴过程,分析雷暴中闪电和降水的特征,以及闪电和固、液态降水对垂直风速的依赖关系,探讨闪电与固、液态降水的时空分布关系和单次闪电表征的降水量(RPF:rainyields per flash)。结果表明:对流云降水中,液态降水占主要部分,但固态降水比液态降水对于垂直风速的依赖性更强。随着对流的增强,固态降水在总降水中占的比重越来越大。首次放电时间不断提前,闪电峰值落后垂直风速峰值,总闪数一开始随对流的增强而增加,对流一旦增强到一定程度,总闪数则逐渐减小。固态降水和液态降水的开始时间和峰值时间均随着对流的增强而不断提前,而液态降水出现时间和峰值时间均提前于固态降水。雷暴云首次放电的时间滞后于液态降水,而闪电峰值提前固态降水峰值或与固态降水峰值同时产生。雷暴云中的放电活动集中在强降水区域前缘的较弱降水区,强降水区对应的闪电较少,对流的增强会使降水区域面积、降水量和降水强度增加。由于液态降水总量远大于固态降水总量,固、液态RPF的数值相差达到一个量级,但单位时间内固态降水和液态降水增加的速率相近。在单位时间内闪电次数越多,RPF则越小,而固态RPF和闪电次数的线性相关性明显好于液态RPF,所以利用固态降水可以更好地预报闪电。这些结果有助于进一步认识闪电和降水的关系,并可为闪电预报提供新的思路。  相似文献   

Survey of historical New Zealand shellfish samples for accumulation of gymnodimine     

David J. Stirling 《新西兰海洋与淡水研究杂志》2013,47(4):851-857

In 1994 a major biotoxin event occurred along the east coast of the South Island, New Zealand. Gymnodimine, a unique bioactive spiroimine, was isolated and characterised from Foveaux Strait dredge oysters (Tiostrea chilensis = Ostrea chilensis) collected during this outbreak. This study reports the results of liquid chromatographic‐mass spectrometric analysis for gymnodimine in 217 samples from eight species of shellfish over the years 1993–99. Of these samples 155, covering six species of shellfish, contained detectable gymnodimine with a range in concentration from 14.8 to 23 400 μg/kg. Gymnodimine‐containing shellfish occurred at 37 of the 63 sites sampled from around New Zealand. This study demonstrates that accumulation of gymnodimine is not limited to T. chilensis and can occur in other shellfish species over much of New Zealand. Gymnodimine is a possible cause of the numerous historical biotoxin screen‐positive results.  相似文献   

贵州晴隆锑矿稀土元素特征与成因探讨   总被引：2，自引：0，他引：2       下载免费PDF全文

朱俊宾  方维萱  刘家军  胡煜昭 《地质找矿论丛》2010,25(2):118-123

对晴隆锑矿含矿层及围岩的稀土元素地球化学特征研究表明,其ΣREE变化较大,但REE配分模式较固定,以明显的负Ce异常、Eu正异常、分配曲线相对平缓为特征。对比该区玄武岩的稀土配分模式图后发现,两者差异较大。结合镜下岩(矿)石的结构和矿物组合特征以及野外实际资料,认为锑等矿质元素是盆地流体通过花鱼井、雷钵硐等NE向的深大断裂运移,由于氧化还原、温度和压力等物理化学条件的改变,沉积赋存于"大厂层"中。  相似文献   

液闪法测量水中氚放射性活度的淬灭效应   总被引：3，自引：2，他引：1  

张向阳  刘福亮  张琳  郭华良 《岩矿测试》2010,29(4):469-471

采用液体闪烁计数法进行放射性同位素测量时存在淬灭效应,而且几乎每个样品的淬灭程度都不同,并影响测量精度。采用液体闪烁计数法测量水中氚的放射性活度,淬灭是难以避免的,因此要进行淬灭校正,才能使不同淬灭程度的样品的测量结果具有可比性。淬灭校正的方法有很多,外标准校正法是一种比较可靠的方法。文章采用氚外标准校正法进行实验,得出淬灭校正曲线即探测效率E与淬灭参数SQP(E)的关系式为E=0.001 3SQP(E)-0.707 6,经过样品验证,该曲线是可靠的。采用外标准校正法适合于大批样品的测量。  相似文献