Mechanism of loading on plates due to explosive detonation     

W. L. Fourney  U. Leiste  R. Bonenberger  D. J. Goodings 《Fragblast: International Journal for Blasting and Fragmentation》2005,9(4):205-217

This paper investigates the various mechanisms and parameters that are responsible for delivering impulse to a vehicle that is unfortunate enough to detonate a buried mine. Small scale tests are used to examine the effects of air blast or ejected sand in imparting impulse to a plate that is located above the surface of the saturated soil that contains the explosive. Parameters such as confinement, stand off distance, depth of burial of the explosive, density of the soil, and saturation level of the soil are also examined.  相似文献   

中国环境化学研究进展     

高国伟  陈锦凤 《云南地理环境研究》2005,17(5):92-96

通过对近年来中国环境化学学科中的环境分析化学、土壤环境化学、水环境化学、大气环境化学和污染生态化学5个大方面研究现状的详细介绍和评述,分析了中国环境化学基础性研究的进展,归纳总结了中国环境化学中已取得的成果及相关的应用,同时通过对目前一些国际上较热门研究内容及研究方向的讨论,指出了中国环境化学学科发展中存在的问题和不足,并对部分相关前沿领域的研究提出了建议。  相似文献   

松花江上游地区汞污染的化学生态效应   总被引：5，自引：0，他引：5  

王宁  朱颜明  朴明玉  孟丹 《地理科学》2005,25(6):737-741

采样分析了吉林省东部松花江上游金矿开采区及其附近水、土壤、动植物及河流沉积物样品中汞的含量，发现河流沉积物中汞的污染相当严重；受其影响当地的植物和两栖类动物——中国林蛙体内总汞和甲基汞含量也明显高于对照组。实验表明，林蛙内脏对汞的富集能力大于肌肉；秋季对汞的富集大于春季；河流沉积物中甲基汞的含量与林蛙体内甲基汞的含量有较好的正相关。汞污染的来源与区域内个体金矿的滥采滥排有直接关系，表明人类活动所产生的有毒重金属在地表过程中出现了化学生态效应。  相似文献   

Development of a soil moisture‐based distributed hydrologic model for determining hydrologically based critical source areas          下载免费PDF全文

Sisi Li  Margaret Gitau  David Bosch  Bernard A. Engel  Liang Zhang  Yun Du 《水文研究》2017,31(20):3543-3557

A simple grid cell‐based distributed hydrologic model was developed to provide spatial information on hydrologic components for determining hydrologically based critical source areas. The model represents the critical process (soil moisture variation) to run‐off generation accounting for both local and global water balance. In this way, it simulates both infiltration excess run‐off and saturation excess run‐off. The model was tested by multisite and multivariable evaluation on the 50‐km² Little River Experimental Watershed I in Georgia, U.S. and 2 smaller nested subwatersheds. Water balance, hydrograph, and soil moisture were simulated and compared to observed data. For streamflow calibration, the daily Nash‐Sutcliffe coefficient was 0.78 at the watershed outlet and 0.56 and 0.75 at the 2 nested subwatersheds. For the validation period, the Nash‐Sutcliffe coefficients were 0.79 at the watershed outlet and 0.85 and 0.83 at the 2 subwatersheds. The per cent bias was less than 15% for all sites. For soil moisture, the model also predicted the rising and declining trends at 4 of the 5 measurement sites. The spatial distribution of surface run‐off simulated by the model was mainly controlled by local characteristics (precipitation, soil properties, and land cover) on dry days and by global watershed characteristics (relative position within the watershed and hydrologic connectivity) on wet days when saturation excess run‐off was simulated. The spatial details of run‐off generation and travel time along flow paths provided by the model are helpful for watershed managers to further identify critical source areas of non‐point source pollution and develop best management practices.  相似文献   

The Fluxes and Behaviour of Plumes Inferred from Measurements of Coherent Structures within Images of the Bulk Flow     

H.C. Burridge  J.L. Partridge  P.F. Linden 《大气与海洋》2016,54(4):403-417

This paper describes how measurements of the movement of identifiable features at the edge of a turbulent plume can be interpreted to determine the properties of the mean flow and consequently, using plume theory, can be used to make estimates of the fluxes of volume (mass), momentum, and buoyancy in a plume. This means that video recordings of smoke rising from a chimney or buoyant material from a source on the sea bed can be used to make accurate estimates of the source conditions for the plume. At best we can estimate the volume flux and buoyancy flux to within about 5% and 15% of the actual values, respectively. Although this is restricted to the case of a plume rising in a stationary and unstratified environment, we show that the results may be of practical use in other more complex situations. In addition, we demonstrate that large-scale (turbulent) coherent structures at the plume edge form on a scale approximately 40% of the local (mean) plume half-width and travel at almost 60% of the average local (mean) velocity in the plume.  相似文献   

固体聚合膜电解浓集法测量天然水中低含量氚的化学淬灭效应研究     

蓝高勇  王华  俞建国  应启和  唐伟  杨会 《岩矿测试》2016,35(4):415-419

固体聚合膜电解浓集法是浓缩氚含量较低(1 Bq/m~3)的天然水样的常用方法,但因水样自身含有杂质离子或电解装置聚合膜带入杂质进入浓集液,使浓集液偏酸性,在测量过程中易产生化学淬灭效应,导致氚的测量值偏低。本文研究了水样自身存在的杂质离子和聚合膜上残留的杂质离子、样品溶液的pH值及其电导率所产生的化学淬灭效应的影响,实验表明,为减少化学淬灭效应,提高测量低含量氚的准确性,需保证水样溶液呈中性,电导率≤1μS/cm,同时避免杂质沉积在聚合膜上。如果水样溶液的pH值偏酸性、电导率大于1μS/cm,可采用酸碱混合型离子交换树脂去除水样中自身的杂质;对于聚合膜引入的杂质,可在电解后的水样中加入微量氨水将其pH值调节至中性。  相似文献   

我国尾矿综合利用研究现状及建议   总被引：2，自引：0，他引：2  

刘志强  郝梓国  刘恋  费红彩  黄敏 《地质论评》2016,62(5):62051277-62051282

尾矿资源综合利用问题已受到世界各国的重视,其对策已由消极的废物处理转向物质再回收,尾矿资源化的发展趋势越来越清晰。但是,我国尾矿综合利用率和发达国家相比还存在较大的差距。大量的尾矿积存,对矿山周边地区环境、土地利用造成了严重的影响。开展典型尾矿资源综合利用技术研究和推广尾矿资源产业化利用技术研究与推广,不但可使原来资源枯竭或资源不足的矿山焕发青春,而且还能够重新成为新的资源基地,以开辟新的材料科技领域,推动科技进步,同时也可以解决环境污染、改善生态环境和整治国土,具有巨大社会、经济和环境效益。因此尾矿的综合利用要做到国家重視、立法保障、评价先行、技术支撑、全部利用,才能真正解决尾矿污染等问题。  相似文献   

A microscale model for air pollutant dispersion simulation in urban areas: Presentation of the model and performance over a single building   总被引：1，自引：0，他引：1  

Ning Zhang  Yunsong Du  Shiguang Miao 《大气科学进展》2016,33(2):184-192

A microscale air pollutant dispersion model system is developed for emergency response purposes. The model includes a diagnostic wind field model to simulate the wind field and a random-walk air pollutant dispersion model to simulate the pollutant concentration through consideration of the influence of urban buildings. Numerical experiments are designed to evaluate the model's performance, using CEDVAL(Compilation of Experimental Data for Validation of Microscale Dispersion Models) wind tunnel experiment data, including wind fields and air pollutant dispersion around a single building. The results show that the wind model can reproduce the vortexes triggered by urban buildings and the dispersion model simulates the pollutant concentration around buildings well. Typically, the simulation errors come from the determination of the key zones around a building or building cluster. This model has the potential for multiple applications; for example, the prediction of air pollutant dispersion and the evaluation of environmental impacts in emergency situations; urban planning scenarios;and the assessment of microscale air quality in urban areas.  相似文献   

天津城区春节期间大气气溶胶污染特征 和数浓度分布     

姚青  刘敬乐  韩素芹  樊文雁 《气象》2016,42(4):443-449

利用天津城区2009-2014年春节期间大气气溶胶观测资料和相关气象资料,重点分析2013和2014年春节期间气溶胶污染特征,探求燃放烟花爆竹以及气象条件对春节期间大气气溶胶的影响。结果表明,受燃放烟花爆竹影响,春节期间PM_(2.5)质量浓度最高值均发生在除夕夜间;持续雾霾天气条件下燃放烟花爆竹,造成2013年除夕夜间PM_(2.5)质量浓度峰值达到1240μg·m～(-3),是近年来最严重的一次;2014年春节期间烟花爆竹燃放量有所减少,加之空气扩散条件较为有利,PM_(2.5)质量浓度显著低于2013年;不同天气条件下,气溶胶数浓度谱分布特征存在明显差异,燃放烟花爆竹期间气溶胶数浓度水平与严重雾-霾天气相当。  相似文献   

邢台市大气稳定度和混合层厚度特征研究   总被引：1，自引：0，他引：1  

郝巨飞  张功文 《气象科技》2016,44(1):118-122

基于1981—2010年邢台市逐日4个时次地面气象观测资料和2014年的同期逐日空气污染API值及气象观测数据,运用修正的Pasquill稳定度分类法和混合层厚度计算方法得出邢台市近30年大气稳定度和混合层厚度变化特征,结果表明:近30年邢台市大气不稳定类呈1.16%/10a增长,中性类呈-1.40%/10a下降,稳定类变化趋势不明显,月变化以中性类和稳定类为主,日变化受太阳辐射强度的影响明显。混合层厚度主要受风速影响,平均厚度460.09m,月变化呈"单峰型"分布。在02:00、08:00、14:00和20:00四个时次上混合层厚度都具有春季大于夏季大于冬季大于秋季的分布特点。经验证发现混合层厚度和不同稳定度等级的出现频率是影响空气质量的重要因子。  相似文献