基于正交试验响应面法的烟气层概率分布计算

为计算随机参数下火灾烟气层温度和厚度的概率分布,该文提出了基于正交试验响应面的可靠度计算方法。通过正交试验表确定分析计算参数组,并借助火灾动力学分析软件计算不同参数组下烟气层的温度和厚度响应,进一步拟合出输入参数和输出参数的响应面函数,在此基础上结合验算点法计算烟气层温度和厚度的概率分布,算例分析表明该方法具有计算精度高、计算量小的特点。     

Review of advances in the thin layer chromatography of pesticides: 2004–2006

Applications of thin layer chromatography and high performance thin layer chromatography for the separation, detection, and qualitative and quantitative determination of pesticides, other agrochemicals, and related compounds are reviewed for the period from July 1, 2004 to November 1, 2006. Analyses are covered for a variety of samples, such as food, crops, biological, environmental, pharmaceuticals, and formulations, and for residues of pesticides of various types, including insecticides, herbicides, and fungicides, belonging to different chemical classes. In addition to references on residue analysis, studies such as pesticide-structure relationships, metabolism, degradation, and lipophilicity are covered, many of which make use of thin layer radiochromatography.     

Influence of dissolved humic substances on the mass transfer of organic compounds across the air-water interface

The effect of dissolved humic substances (DHS) on the rate of water-gas exchange of two volatile organic compounds was studied under various conditions of agitation intensity, solution pH and ionic strength. Mass-transfer coefficients were determined from the rate of depletion of model compounds from an apparatus containing a stirred aqueous solution with continuous purging of the headspace above the solution (dynamic system). Under these conditions, the overall transfer rate is controlled by the mass-transfer resistance on the water side of the water-gas interface. The experimental results show that the presence of DHS hinders the transport of the organic molecules from the water into the gas phase under all investigated conditions. Mass-transfer coefficients were significantly reduced even by low, environmentally relevant concentrations of DHS. The retardation effect increased with increasing DHS concentration. The magnitude of the retardation effect on water-gas exchange was compared for Suwannee River fulvic and humic acids, a commercially available leonardite humic acid and two synthetic surfactants. The observed results are in accordance with the concept of hydrodynamic effects. Surface pressure forces due to surface film formation change the hydrodynamic characteristics of water motion at the water-air interface and thus impede surface renewal.     

改性膨润土作为垃圾渗透液防渗层的实验研究

本文以天然钠基膨润土为原料,采用水溶液聚合法,在室温条件下,通过改性聚丙烯酰胺对膨润土进行直接插层改性,制备了一种新型聚丙烯酰胺改性膨润土防渗材料。以此防渗材料作为防渗层,选用沈阳大辛填埋场的垃圾渗透液为处理对象,在动态实验下,就其对实际垃圾渗滤液中主要污染物去除的有效性和控制垃圾渗滤液渗透的可行性进行研究。抗渗性能测试结果表明,改性膨润土防渗性能较好,渗透系数为1．0×10^-7cm/s,达到固体废物填埋场的防渗材料国家标准1．0×10^-7cm／s的使用要求。改性膨润土防渗层对COD、氨氮、重金属离子去除效果较好,吸附作用较强,COD和氨氮最大去除率分别达到81％和91％,TFe、Zn^2＋和TCr的最大去除率分别达到71％、58％和73％。实验结果验证了本研究所制备的改性膨润土防渗材料具有优良的抗渗、截污性能。     

The role of periodic boundary forcing in plankton pattern formation

We consider one and two-dimensional minimal models in plankton dynamics. The influence of oscillating boundary forcing functions as agents for triggering pattern formation is discussed. In particular it is found that in these conditions population waves arise for one dimensional models, while for two dimensional models, different amplitudes and frequencies in the boundary forcing generate definite patterns, mimicking the boundary term. This happens even though the model we investigate is very simple. The emergence of these features is an interesting metaphor for the fundamental biological problem of how pattern formation processes may be inevitable in natural heterogeneous ecosystems.     

厦门市气候特征变化与酸雨形成研究

对地面风场的研究表明,厦门存在局地和海陆风环流,自1955年以来年平均风速、混合层厚度均呈现下降趋势,大气污染物的水平和垂直扩散能力也呈下降趋势。降水酸度随海拔高度的变化情况表明,海陆风环流有利于酸性污染物的积累,且锋面降水过程中的光化学污染加重了降水的酸化程度。     

激发剂作用下的盐石膏废渣的水化过程

运用Kondo模型,研究了在激发剂硫酸钠作用下盐石膏废渣的水化过程.盐石膏废渣的水化过程分为3个阶段,第1、第3阶段受扩散作用控制;第2阶段受相边界反应控制.分别研究了激发剂溶液浓度和温度对相边界反应阶段水化速率的影响,结果表明,在0—0.60 mol.L-1范围内,增大激发剂溶液浓度可使水化速率常数k增大,在12℃≤...     

Potential and Shortcomings of Numerical Weather Prediction Models in Providing Meteorological Data for Urban Air Pollution Forecasting

The last decade progress in numericalweather prediction (NWP) modelling and studies of urbanatmospheric processes for providing meteorological data forurban air pollution forecasting is analysed on examples ofseveral European meteorological centres. Modern nested NWP models are utilising land-use databasesdown to 1 km resolution or finer, and are approaching thenecessary horizontal and vertical resolution suitable forcity scale. The recent scientific developments in the fieldof urban atmospheric physics and the growing availabilityof high-resolution urban surface characteristics datapromise further improvements of the capability of NWPmodels for this aim. A strategy to improve NWP data forthe urban air pollution forecasting is suggested.