抗红外烟幕中固体消光材料的研究进展

开发高效环保型抗红外烟幕已引起了国内外广泛关注,为此,世界各国积极致力于发展低毒固体红外消光材料,现已报道的有金属类、新型碳材料类和抗红外复合材料。本文介绍了固态气溶胶粒子红外消光特性的研究现状,综述了上述三类材料的研究进展,指出了气溶胶粒子的消光特性仿真研究、纳米新型碳材料和金属薄膜复合材料仍是未来重点研究的方向。建议积极关注和探索纳米红外吸波材料、单向吸波材料和金属化生物体红外吸波材料,这些材料有望成为新一代的抗红外烟幕消光材料。附参考文献63篇。     

高性能混凝土早期抗裂试验研究

为减少高性能混凝土早期收缩开裂,利用非接触测量技术,通过测量高性能混凝土早期自生及单面干燥条件下的收缩,研究减缩剂、聚丙烯纤维及不同减水剂对高性能混凝土早期自生及干燥收缩的影响.在此基础上,利用板式混凝土早期收缩开裂试验架,对高性能混凝土进行约束试验,研究减缩剂、减缩剂 聚丙烯纤维等对高性能混凝土早期抗裂的作用.结果表明:减缩剂、聚丙烯纤维、减缩剂 聚丙烯纤维及聚羧酸高效减水剂均有减缩抗裂效果.其作用大小为:减缩剂 聚羧酸高效减水剂＞减缩剂 FDN高效减水剂＞减缩剂 聚丙烯纤维＞聚丙烯纤维.     

温变条件下含气量对混凝土温度应力影响

试验主要利用ANSYS有限元方法,模拟分析了温变疲劳条件下,混凝土温度应力分布及其随时间的变化规律,以及含气量对混凝土温度应力的影响。研究结果表明:随着含气量的增加,混凝土内外最大温差和最大温度应力逐渐增大。低水灰比混凝土最大温差为10.5℃,最大温度应力为2.76MPa;高水灰比混凝土最大温差为15℃,最大温度应力为3.83MPa。不掺引气剂时,水灰比越低,混凝土传热时间越短,最大温度应力越小。     

恒温环境掺外加剂混凝土中钢筋锈蚀分析

分析某工程在竣工后不足5年、恒温环境使用、掺加外加剂的混凝土结构中钢筋锈蚀的原因,探讨混凝土结构的设计依据、混凝土组成材料、氯离子含量的限值、混凝土结构的施工质量及使用环境等对钢筋锈蚀产生的影响,强调应实施混凝土的耐久性设计、控制原材料质量、施工质量、混凝土结构的防护质量等全过程质量控制.     

平面SV波入射下弹性半空间中三维球形洞室的动力响应

采用一种间接边界积分方程法求解了平面SV波入射下弹性半空间中三维洞室的动力响应问题。通过与已有结果的比较,验证了方法的计算精度。在此基础上,以半空间中圆球形洞室为例,对地表位移响应和洞周动应力集中特征进行了详尽的参数分析,并与二维模型进行了比较。研究表明:二维和三维模型对平面波的动力响应在平面内存在一定的相似性,但在波型转换上存在显著差别,尤其体现在响应峰值及空间分布特征上,并且随着频率的升高,空间分布差异愈加明显;在出平面方向,三维洞室周围存在着显著的波散射效应,而二维模型难以描述这种出平面波型转换现象。     

高温下混凝土裂缝对温度场的影响

通过对带(预制)裂缝混凝土试件进行明火升温试验,研究高温下裂缝对混凝土温度场的影响.依据传热理论分析建立带裂缝混凝土试件截面温度计算模型,然后用数学软件MATLAB进行数值计算并与试验结果进行对比.结果表明:高温下裂缝区域的主要传热方式为热传导;相对于无裂缝处,有裂缝处测点温度更高;总体上测点的温度随裂缝宽度的增大而增大,远离裂缝的测点温度受裂缝的影响较小;不同测点的计算与实测升温曲线总体变化趋势一致,依据传热理论分析建立的带裂缝混凝土试件截面温度计算模型较为可靠.     

Environmental Implications of Treatment of Coastal Sewage Discharges

The environmental implications of implementing the requirement for treatment of coastal sewage prior to discharge, which were put forward in an EC draft Directive on municipal waste-water treatment, are examined. In order to establish the current situation, the results of a national survey of coastal and estuarine sewage discharges are presented. A review of the impact of sewage discharges on the marine environment is presented in conjunction with an assessment of the impact of sewage-treatment processes on the land and in the air. These aspects are integrated into overall conclusions about net environmental impact. Finally, a decision-tree approach to the assignment of priority to additional action required at individual locations is developed.     

A FRAMEWORK FOR CLIMATE RISK MANAGEMENT APPLIED TO A UK WATER RESOURCE PROBLEM

Climate risk management is a new and evolving area and many decisions are likely to be affected by climate risks over the long-term. This paper presents a decision-making framework designed for managing climate alongside nonclimate risk factors. The framework describes a process that should help identify and manage these risks. It can be used to help decision-makers answer questions about whether adaptation is required, and, if so, which measures should be implemented. Adaptive management is recommended as a useful approach for dealing with climate and other uncertainties. This paper describes an application of the framework to a water resources case study. Feedback from training workshops based on four different case studies suggests the framework provides at minimum a useful (post-hoc) decision analysis tool. Potential users, who include planners, consultants and policy-makers have been largely positive about the prospective utility of the framework.     

Impacts of Sewers on Groundwater Quality

This paper summarizes the findings of a recent research project on groundwater contamination from leaking sewers, which was completed for the Construction Industry Research and Information Association. Fifty-four incidents were identified in England and Wales from a combined questionnaire survey and literature review. In addition to recorded incidents, the poor quality of many urban groundwaters suggests some effects from leaking sewers. Age is considered to be the most significant characteristic governing leakage from sewers; ground conditions (predominantly aquifer vulnerability) and usage (private versus public ownership) are also important factors relating to the likelihood of groundwater pollution from leaking sewers. Recommended strategies for reducing groundwater contamination include (a) modification of existing criteria for the service performance grading of existing sewers, (b) improved construction of new sewers in appropriate areas, (c) increased groundwater monitoring, and (d) risk assessments for new groundwater sources.