声屏障系统设计探讨

对声屏障设计,尤其是封闭式声屏障的设计作了分析与探讨,系统地分析了声屏障设计过程中需要考虑的问题,以及跨专业的综合应用,将封闭式声屏障的系统化设计进行了总结。该总结分析对道路声屏障设计,尤其是对城市内封闭式声屏障的设计具有较大的参考与借鉴意义。     

人工快渗技术在我国农村地区水污染治理中的应用研究

概述了我国农村地区水污染现状、排放特征、主要处理工艺及其优缺点,在对人工快渗系统工艺原理和污染物去除机理深入分析的基础上,总结归纳了人工快渗工艺的技术经济优势,并结合技术的工艺改进和完善,探讨了人工快渗技术的适用性。然后结合深圳市白花洞村、四川省绵阳市北川县及北京昌平区农村工程实践,分析了人工快渗技术在村级分散型污水处理工程中的实际运行效果。理论研究和工程实践均表明:人工快渗技术及其改进工艺组合系统具有工艺简单、建设运行成本低、污染物去除效率高、出水效果好等特点,可有效地解决目前农村地区因受到资金、技术、人才等因素限制造成的污水处理能力低的问题,是一项十分适合我国农村地区的污水处理技术。     

Review: Windows of exposure to pesticides for increased risk of childhood leukemia

Leukemia is the leading cause of cancer resulting in mortality of children, and there is some evidence suggesting the increased incidence rate increasing during the recent decades. Limited human evidence indicates an increased risk of developing leukemia in childhood as a result of pesticide exposure, with possible significance of exposure occurring during the developmental periods including preconception, pregnancy, and childhood. This review examines the results of relevant literature on the timing of pesticide exposure and leukemia diagnosed in childhood. Results suggest that the risk from pesticide exposure seems to be greater during pregnancy. Other findings indicate that maternal occupational exposure may be more of a greater concern than the paternal occupational exposure; and that the residential indoor use of pesticides tends to result in higher risk estimates than the residential outdoor use. Only limited data are available on particular pesticides, genetic factors, critical windows of exposure during development, and their association with different histological types of leukemia.     

带混合时间窗的多目标危险化学品运输路径优化

为降低危险化学品运输风险,使路径选择更加科学、切合实际,从责任主体、社会影响等方面综合考虑危险化学品运输相关主体,根据各主体目标对影响运输路径选择的指标进行重新识别和细分,提出5大指标体系。应用熵权法计算出各指标权重,建立混合时间窗条件下的多目标危化品运输路径优化模型,通过改进的多目标遗传算法求出Pareto最优解。结果表明,不同时间点出发会产生不同的Pareto最优解,并且可得到每条最优路径的出发时间窗,每个最优解代表了某项指标达到相对最优时的路径。混合时间窗较符合实际情况,基于出发时间窗及生成的多条最优路径,决策者可根据决策偏好及关注重点以较高效率选出最合适的路径。     

三种常用外墙可燃保温材料竖向燃烧特性数值模拟研究

运用FDS软件对外墙保温材料竖向燃烧的发展规律进行了研究.根据具体的工程参数,对挤塑聚苯板、模塑聚苯板和聚氨酯三种常用外墙可燃保温材料的燃烧参数进行设定,分别选取窗口火、墙角火两种情况进行数值模拟与分析.模拟结果显示:火焰的蔓延高度随时间按照y=at2+bt+c的关系变化,而火焰前锋则以vp=1/(α+βt)的速度竖向蔓延.     

武汉城市圈节能建筑的处理方法及利用

从武汉城市图建筑节能的重要性及武汉市建筑节能的现状入手,指出为达到建筑节能50％的标准,武汉节能建筑处理方法应从建筑设计、建筑施工、节能技术开发应用及建筑节能管理等多方面下功夫．图8,参7．     

Looking through the postdisaster policy window

Policy windows are transitory opportunities during which the likelihood of adopting new policy or legislative proposals is greater than usual. Accepted wisdom has held that natural disasters serve as focusing events that generate policy windows in their wake. This paper highlights the need for a more circumscribed understanding of when and where policy windows occur based on the experiences of three US regional planning organizations: a hand-picked commission of community leaders, a council of governments, and a special-purpose substate organization. The first operated in the San Francisco Bay Area of California following the Loma Prieta earthquake (October 1989), and the other two in South Carolina's Atlantic coastal plain after Hurricane Hugo (September 1989). The analysis concludes that natural disasters did not transform the agenda or mission of these entities. Policy windows were neither automatic outcomes of focusing events nor did they ensure the adoption of pertinent policy within the organizations investigated. Several conditions are minimally necessary for using policy windows to bring about hazard mitigation: comprehensive institutional conceptualization of hazards management, institutional strength and flexibility, and well-placed, effective policy entrepreneurs.     

新型声屏障材料泡沫陶瓷

通过对泡沫陶瓷吸声特性的介绍 ,指出泡沫陶瓷具有良好的声学性能 ,力学性能 ,耐候性 ,防火性等特点 ,其材料制成的吸声元件 ,在中低频具有良好的吸声性能 ,适于在公路建造声屏障时使用     

MTO/FCC反应器高温高压设备隔热衬里对金属壳体温度分布的影响

MTO/FCC反应器高温高压设备的隔热衬里发生局部开裂或破碎时,该部分衬里将保持全部或部分隔热功能。以衬里的破坏厚度和破坏高度作为控制变量,研究衬里破坏程度对衬里-金属结构温度分布的影响。结果表明:设计温度为750℃时,随着衬里破坏厚度和破坏高度的增加,衬里-金属结构温度逐渐升高,且存在温度上限;当衬里设备存在"施工缝"缺陷时,随着衬里破坏厚度的增加,衬里-金属结构的温度增高,最大温度为546℃;当衬里破坏厚度超过80%时,金属壳体最高温度为346℃,验证了国外手册中衬里破坏决策书选取350℃为极限温度条件的科学性和适用性。     

在较高位置构筑大型隔声屏的降噪工程

在控制工厂二层楼顶的风机群及冷却塔群的噪声工程中，复式隔声屏获１８ｄＢ（Ａ）的降噪效果。主屏由轻结构板及隔振底盘组成。主习体被若干伸缩隔断以消除热应力。副屏是为了减少主屏隔振底盘缝的漏声。迷路消声构造减少伸缩缝的漏声。为了抗风，主习必须锚固，并且屏体自身应有良好的结构。