中波台电磁辐射叠加影响估算及与实测对比分析

以某中波电台为例,对多个不同频率的中波发射台同时运行时复合场强进行理论估算,对电磁辐射叠加影响进行分析,并将理论估算值与该台电磁辐射环境现状监测数据进行比对,得出距离发射塔近,复合场强理论估算值高于实测值,距离较远理论估算值与实测值较接近等结论。     

北京市某高层建筑高空电磁辐射环境影响分析

选取北京市某代表性高层居民楼顶平台作为高空电磁辐射环境水平监测点进行综合场强和选频监测,评价总体电磁辐射环境水平,并分析监测区域电磁辐射能量的来源。结果表明：该高空监测区域的电磁辐射环境总体水平低于国家规定的公众照射导出限值,但高于地面水平。监测区域主要受30 km 外的中波台影响,其次是9 km 外的中央电视塔。影响最大的是639 kHz频率的中波信号,占100 kHz～300 MHz总场强的95％以上,其次是1．28 MHz频率的中波信号。提出,开展敏感建筑物规划建设时,应考虑中波的传播特性和对环境的影响。     

房地产开发地铁振动达标距离研究

已建和待建的多条地铁线路穿过某房地产开发地块,为了防治地铁运行对建筑造成振动环境影响,需要设定建筑靠近地铁的最小达标距离,包括采取减振措施后的距离。通过现场系统实验监测结合数值模型分析,从工程实践的角度提出了上述距离。对于实验中观察到随距离出现振动局部放大以及进口与国产仪器监测结果不同的现象,佐证了有关学者的理论与实验分析,提出:(1)现有地铁环境影响评价报告常用的60m评价范围偏小,推荐可扩大至80~100m;(2)迫切需要新的振动环境标准发布,避免有关项目的环境管理要求偏低。     

Electrochemical study of the fungicide acibenzolar-s-methyl and its voltammetric determination in environmental samples

The electrochemical behavior of new generation fungicide acibenzolar-s-methyl (S-methyl 1,2,3-benzothiadiazole-7-carbothioate, ASM) on the hanging mercury drop electrode (HMDE) was investigated using square wave adsorptive stripping voltammetry. This method of determination is based on the irreversible reduction of ASM at the HMDE. The well-defined ASM peak was observed at ?0.4 V (vs. Ag/AgCl) in BR buffer at pH 2.2. The reduction peak current was proportional to concentration of ASM from 1.0 × 10^?8 to 6.0 × 10^?8 mol L^?1 with detection and quantification limit 3.0 × 10^?9 and 1.0 × 10^?8 mol L^?1, respectively. The applicability of the developed method for analysis of spiked samples of tap water, river water, and soil is illustrated. The effect of adsorption on the mercury electrode was studied in detail using the AC impedance method. Possible interferences with other common pesticides and heavy metal ions were examined. Clarification of the electrode mechanism was made using cyclic voltammetry (CV) technique.     

基于方波溶出伏安法的电化学传感器检测水体中痕量铅

基于方波溶出伏安法运用丝网印刷电极探索了一种利用电化学传感器检测水样中痕量铅的方法.得到了该检测方法的最佳参数:方波频率30 Hz,振幅80 mV,电位增量5 mV;0.5 mol/L的支持电解质(KCl);沉积电位-1.1 V,沉积时间400 s.在该优化条件下,在浓度为25 ～ 500μg/L范围内溶出峰电流与铅离子浓度呈良好的线性关系(R2=0.9945).对于几种其他金属离子的干扰实验结果表明,Mn2的存在严重抑制铅离子的峰电流.     

超声波-铁粉协同降解五氯酚

通过超声波-铁粉联合体系协同降解废水中的五氯酚(PCP).实验结果表明:降解120 min后,PCP去除率可达90.4％;在该体系中铁粉被逐渐腐蚀成Fe2+,随降解时间的延长,Fe2+浓度逐渐增加;体系中的Fe2+可以促进·OH的产生,并且可以与超声空化作用下产生的H2O2发生Fenton试剂氧化反应降解PCP;超声波...     

“一一·二四”海难渤海风场的数值模拟

用中尺度数值模式 ＭＭ５对 １９９９年 １１月 ２４日烟台附近发生重大海难事故的渤海风场进行了数值模 拟，探讨了该次冷锋大风的风场特征和影响机制．结果表明：用９０ｋｍ的粗网格可以成功地模拟地面冷高压 与锋面的发展和移动，以及高空环流形势的演变．而通过３０ｋｍ细网格的模拟发现，在冷锋后的行星边界层 中．存在着一条宽度为 ２００ ｋｉｎ的中尺度强风带，最大风速位于 ９２５ｈＰａ，它与高空的极锋急流并不相连；细 网格还模拟出了渤海中尺度低压的发展过程，它使近地面层大风的强度显著加强．模拟还表明，海陆差异对 近地面的风场分布有重要的影响，强风带移入渤海后，在渤海海域形成一个 ２００—３００ ｋｍ的中尺度强风 区．因此，采用具有较高分辨率的中尺度数值模式，对提高渤海大风的预报水平，避兔海难事故的发生更具 有重要意义．     

A SIMPLE HYDRAULIC SIMULATOR1

ABSTRACT: A simple simulator was constructed, calibrated, programmed and used in management studies of a hydraulic system containing two pumping stations in series, connected by canals and reservoirs. The features of the model, its calibration and use are described, and comparisons between measured and computed hydraulic behavior are presented.     

三烧溴化锂集中制冷空调系统改建设计

武钢三烧区域改建了二台大连三洋蒸汽型双效溴化锂吸收式制冷机。叙述了该改建项目的主机选型、参数选定、设计特点等。     

Simplified model for the evaluation of the effects of explosions on industrial target

The evaluation of vulnerability of process equipment to explosion is a central issue in the analysis of industrial risks. In this work, we have developed a simplified model, however based on fundamental equations, which includes structural and fluid–dynamic parameters for the target (the industrial equipment) and for the impacting pressure wave (shock waves) or object (fragment, debris) produced by different type of chemical explosions.The validity of methodology has been assessed by case histories. Several insights on the dynamic of structural interaction of the explosion with the target have been obtained, with specific reference to escalation effects.The model derives from the well-known Johnson's number, often adopted in impact engineering.