通信铁塔影响建筑物防雷安全计算公式之合理性探讨

以一个发生过严重雷灾事故的屋顶通信铁塔为例,分别利用国际电信联盟ITU-K56《无线通讯基站的雷电防护》和国际电报电话咨询委员会CCITT《防雷手册》中的公式计算出建筑物安装了通信铁塔后的年预计雷击次数,并将之与未安装通信铁塔时的年预计雷击次数进行对比,两者的计算结果存在显著差异。基于雷击条件相似原则,参照移动公司通信铁塔每年遭受雷击次数的实际统计数据,对这两个计算公式的合理性问题进行了探讨。研究结果表明,CCITT《防雷手册》中的计算公式更具合理性,计算结果更加接近实际值,计算方法更能准确地评估铁塔对所在区域的建筑物及电子电气设备的防雷安全所造成的影响。     

Effect of Flow Depth and Velocity on Nitrate Loss Rates in Natural Channels1

Carleton, James N. and Yusuf M. Mohamoud, 2012. Effect of Flow Depth and Velocity on Nitrate Loss Rates in Natural Channels. Journal of the American Water Resources Association (JAWRA) 1‐12. DOI: 10.1111/jawr.12007 Abstract: Loss rates of nitrate from streams and rivers are governed by movement of the ion from water column to anoxic bed sediments. Quantitative representations of nitrate in streams and rivers have often treated such losses as governed by first‐order mechanisms that are invariant with respect to potential modulating factors other than temperature. Results of studies in recent years, however, suggest that rates of water column‐sediment mass transfer are influenced by stream geometry and associated hydraulics. We develop expressions for the instream nitrate loss rate coefficient, k, as a function of water velocity and depth, using hydraulic geometry to empirically relate velocity to depth for two cases: (1) variability in mean conditions among reaches; and (2) temporal variability in conditions at a single reach, under changing flow. The result is expressions for k as functions of water column depth. Measured stream k values reported in the literature are shown to be well represented by expressions developed for the first case, and the potential for application to probabilistic analysis is briefly examined. We explore the latter case using the Hydrologic Simulation Program – FORTRAN (HSPF) model, modified to incorporate the dependence of k on instantaneous stream depth. In example simulations of two nitrate‐exporting watersheds, the incorporation of depth‐dependence of k produces improvement in the model’s ability to match observed stream nitrate concentrations.     

上海市自来水中铀浓度调查

测定自来水中铀浓度及其变化规律，对评估饮用水质量及公众接受的铀放射水平有较大意义。该文介绍了经过一年连续监测所获得的上海市自来水中铀浓度及其变化。结果表明，上海市自来水中铀浓度在０．０２５￣０．２８μｇ／Ｌ之间，年均值为０．１１２μｇ／Ｌ；一年中的１２月－１５月浓度较高，６－１１月浓度略低，其中３月份浓度最高，８月份深度最低，上海市自来水中铀浓度较低，比全国平均浓度低一个数量级。     

Air Pollution Modelling at an Urban Scale – Russian Experience and Problems

Urban concentration fields are extremely inhomogeneous andtheir gradients are very high. It results in specificproblems when modelling air pollution at the urban scalethat are analysed in this paper. Some examples ofmisrepresentation of the urban concentration field,computed with the use of the source-receptor type models,are given here. They can help in understanding the natureof the problems we face and reveal deficiencies of thecomputational technologies in use. Filtering of thecomputed fields is suggested as an instrument for improvingtheir quality. Its efficiency is proved on the test runs.An algorithm for refinement of the filtered fields isintroduced in this paper.     

乌鲁木齐市烟尘控制区验收监测结果分析

通过对验收监测结果的分析，找出了乌鲁木齐市烟尘控制区的烟尘排放特点并提出了相应的建议。     

Geographic Concentration in China''''s Manufacturing

This paper empirically examines variations and changes in manufacturing concentration and their determinants in China over the 1980-2003 period with a sample of 26 industries. The analysis indicates that average industrial concentration has increased during the 1990s. Studies show that scale economies and industry policies are important determinants for industries geographical concentration; factor endowments and the location of foreign direct investment are also found to have a positive effect on concentration.     

基于区间数排序的水环境质量评价方法研究

目的：地表水水质随季节性变化较大,为了更准确地评价某地区全年地表水环境质量,尝试将不确定多属性决策方法中的区间数排序法用于水质评价。方法：将地表水环境质量标准值与不同时期的水质监测数据分别定义为区间数,利用区间数比较的可能度公式,得出两者可能度关系并进行排序。排序结果显示,浑河东陵大桥处2006年水质劣于地表水V类标准值的可能度为0．531,即2006年浑河东陵大桥处水质为劣V类。结论：基于区间数排序的地表水环境质量评价方法考虑了全年不同时期的水质变化情况,与模糊综合评判法得出的结果基本一致,可比较准确地评价某地区全年水质状况。     

正渗透膜分离技术及其在水处理中的应用与研究

渗透是一种仅依靠渗透压驱动的分离过程,基于渗透现象发展起来的正渗透膜分离技术,目前在国际上得到了广泛的研究。文章综述了正渗透膜分离过程的基本原理、影响因素以及国际上的应用研究现状,并展望了未来该领域的研究方向。     

UASB工艺在甘蔗渣浆纸厂堆垛蔗渣渗出液处理中的应用

利用甘蔗渣生产纸浆厂堆垛蔗渣产生的渗出液CODCr,浓度高达8000～13000mg／L,属于较难处理的高浓度有机废水。将UASB废水处理技术应用于处理清洁堆垛蔗渣产生的渗出液,不仅能够获得良好的处理效果,而且能降低废水处理成本,从而实现经济效益、环境效益和社会效益三赢。     

O3浓度升高对银杏及油松BVOCs排放的影响

以生长在沈阳市区内的银杏及油松为试材,开顶式熏气室模拟升高O₃浓度（80 nmol·mol^-1）和正常大气O₃浓度（≈30 nmol·mol^-1）条件,采用GC-FID技术对银杏及油松的异戊二烯和7种单萜类物质的排放速率进行测定,探讨高浓度O₃对单株银杏及油松挥发性有机物排放规律的影响.结果表明,O₃浓度增高可以显著提高银杏和油松的异戊二烯排放速率（p＜0.05）,及银杏Δ3-蒈烯的排放速率（p＜0.05）,其分别达到1.96、 9.71和0.09 μg·(g·h)^-1,而对于其他单萜物质的排放速率,2种树木对高浓度的O₃熏蒸均没有表现出显著的变化;树种不同,排放的BVOCs组成也不同,自然条件下银杏排放的BVOCs以异戊二烯为主,而油松以α-蒎烯为主;高浓度O₃熏蒸下油松释放的异戊二烯达到其BVOCs组成的64.73%,增加大气O₃浓度改变了树木挥发性有机物的组成比例.因此,O₃浓度升高对银杏及油松BVOCs排放规律具有显著影响.