Impacts of Upstream Building Width and Upwind Building Arrangements on Airflow and Pollutant Dispersion in a Street Canyon

A two-dimensional numerical model for evaluating the wind flow and pollutant dispersion within a street canyon was first developed using the FLUENT code, which was then validated against a wind tunnel experiment. Then, the effects of the upstream building width and upwind building arrangement on the airflow and pollutant dispersion inside an isolated street canyon were investigated numerically. The numerical results revealed that: (1) the in-canyon vortex center shifts downwards as the upstream building width increases; (2) the recirculation zone covers the entire upstream building roof for the cases when W/H = 0.5, 1.0, 1.5, and 2.0 (W is the upstream building width and H is the building height), whereas the flow reattaches the upstream building roof for the cases when W/H = 2.5 and 3.0; (3) when the upstream building width is shorter than the critical width W_C (= 2H), an increase in the upstream building width leads to an increase in the pollution level on the leeward wall of the canyon and a decrease in the roof-level concentrations at the upstream building; (4) when the upstream building width is longer than the critical width, the roof-level concentrations at the upstream building are negligibly small and the pollution level on the leeward wall of the canyon is almost unaffected by a further increase in the upstream building width; (5) when the buildings are placed upwind of the canyon, the flow attaches the upstream building roof and, therefore, almost none of the pollutants are distributed on the upstream building roof; and (6) the pollution levels inside the canyon and on the downstream building roof increase significantly with the number of upwind buildings.     

废轮胎与煤共热解失重特性研究

采用热解重量分析法研究了废轮胎粉、炼焦煤粉(简称煤粉)及混合样的热解特性。实验结果表明,废轮胎粉的热解出现三个显著的失重峰,煤粉热解仅出现一个显著失重峰。与煤粉热解相比,废轮胎粉热解开始失重温度和失重基本结束的温度相对较低,失重速率较大,且失重量较大。煤粉与废轮胎粉的显著失重存在重叠的温度区间(360～450℃),说明废轮胎粉与煤粉可以进行共热解。随废轮胎粉质量分数增加,共热解物料总失重率增加。废轮胎粉与煤粉共热解存在协同效应,在280～540℃时协同效应抑制共热解挥发分的逸出,导致失重量降低,最大失重速率峰温升高;高于540℃后,协同效应促进共热解反应,使共热解总失重率增大。     

应用模糊聚类方法进行四川国土分区研究

本文介绍采用模糊聚类方法进行四川省国土综合分区研究的情况和主要结果。提出将全省划分为8个国土区的结论,论述了各区的前景,探讨了定性与定量分区方法的先进性。     

粉尘爆炸反应工程学简要综述

１９９３年在波兰召开的第五届国际粉尘爆炸学术会议上，邓煦帆曾在论文中提议建立粉尘爆炸反应工程学，并提出学科的目的意义、性质、主要组成部分和研究方法。本文拟将国内外有关本学科范围内的贡献，加以简要综述，以期能逐渐形成本学科的自身体系和特点。     

水射流技术在放顶煤综采中的应用

介绍水射流技术在放顶煤综采中的应用。通过具体的技术经济指标说明在一定的条件下水系与放顶煤综采相结合是提高采煤效益的新途径。还说明，水射流技术在采矿工业中有着广阔的应用前景。     

小氮肥厂的三废及其治理

论述了小氮肥厂生产中废水、废气和废渣和产生及其废水，废气的治理方法与效果。介绍了利用废渣制砖和水泥的技术。     

岷江生态环境问题及其对策研究

本文主要探讨岷江流域的生态环境问题及其对策。全文分为两个部分。(1)研究岷江生态环境问题;(2)解决岷江生态环境问题的主要对策。     

环境评价污染气象观测与分析的几个问题

就实际环评工作中污染气象观测与分析中资料的选取与分析,地面常规气象资料的统计与分析,大气边界层观测与分析等几个问题提出了看法和建议。     

煤层底板采动导水破坏深度计算的神经网络方法

在综合分析影响煤层底板采动导水破坏深度因素的基础上 ,应用人工神经网络方法 ,建立了底板破坏深度的计算模型。该模型利用现场观测资料作为学习训练样本和测试样本 ,对模型的测算结果、理论计算值和实测值进行了对比分析。结果表明 :用神经网络方法计算底板破坏深度考虑的因素更加全面 ,结果更接近于实际。笔者研究的计算模型和测算方法 ,为承压水上安全采煤决策提供了科学依据。     

钻井环境污染源头控制技术综述

通过对国内外石油行业的钻井环境污染源头控制技术的简单综述,分析了钻井工艺可采用小孔径钻井、连续软管工艺、新型固控设施等的技术特点,对选择合适的钻井液以及应用环保型钻井液来减轻污染方面进行了探讨。并展望了我国石油行业钻井环境污染源头控制技术的发展。