Influence of floc dynamic protection layer on alleviating ultrafiltration membrane fouling induced by humic substances

Cake layer formation is inevitable over time for ultrafiltration (UF) membrane-based drinking water treatment. Although the cake layer is always considered to cause membrane fouling, it can also act as a “dynamic protection layer”, as it further adsorbs pollutants and dramatically reduces their chance of getting to the membrane surface. Here, the UF membrane fouling performance was investigated with pre-deposited loose flocs in the presence of humic acid (HA). The results showed that the floc dynamic protection layer played an important role in removing HA. The higher the solution pH, the more negative the floc charge, resulting in lower HA removal efficiency due to the electrostatic repulsion and large pore size of the floc layer. With decreasing solution pH, a positively charged floc dynamic protection layer was formed, and more HA molecules were adsorbed. The potential reasons were ascribed to the smaller floc size, greater positive charge, and higher roughness of the floc layer. However, similar membrane fouling performance was also observed for the negative and positive floc dynamic protection layers due to their strong looseness characteristics. In addition, the molecular weight (MW) distribution of HA also played an important role in UF membrane fouling behavior. For the small MW HA molecules, the chance of forming a loose cake layer was high with a negatively charged floc dynamic protection layer, while for the large MW HA molecules it was high with a positively charged floc dynamic protection layer. As a result, slight UF membrane fouling was induced.     

颗粒物分界层Mie散射激光雷达识别的sigmoid算法

基于成都市2013年6月~2015年5月期间由Mie散射激光雷达探测的大气消光系数廓线资料,发现混合层以上在颗粒物消光和分子消光之间一致存在一个S型的过渡区,利用sigmoid函数对此分布形态进行模拟,通过计算该函数上下曲率最大点所在的高度,据此提出了颗粒物分界层Mie散射激光雷达识别的sigmoid算法.针对该算法模拟效果的分析表明,颗粒物分界层过渡区附近大气消光系数理论廓线和实测廓线保持了高度的相关性,二者在春夏秋冬四季的相关系数（R）分别为0.9971±0.0052、0.9935±0.0167、0.9979±0.0038和0.9990±0.0021（均通过α=0.05的显著性检验）.基于sigmoid算法计算的颗粒物分界层过渡区与成都市温江站探空资料得到的逆温层之间存在很好的对应关系.     

7B04铝合金和30CrMnSiA钢短期腐蚀的电化学行为研究

目的研究7B04铝合金和30CrMnSiA合金钢试样的电化学性能。方法采用电化学实验、扫描电子显微镜(SEM)、腐蚀坑深度测试分别对7B04铝合金和30CrMnSiA合金钢试样在是否经过天然海水浸泡的情况下进行测试分析,得到微观腐蚀形貌和腐蚀坑深度以及试样表面不带锈和带锈时的电化学性能。结果随着Na Cl浓度增大,7B04铝合金和30CrMnSiA钢的自腐蚀电流变大,两者之间存在明显的电位差,接触后会发生电偶腐蚀。电偶电流与阴阳极面积比和Na Cl浓度有关,阴阳极面积比增大或Na Cl浓度升高均会导致电偶效应增强。经过海水短期浸泡后,7B04铝合金表面的锈层不仅没有起到抑制腐蚀的作用,反而使自腐蚀加重,但电偶效应确实有所减弱。结论沿海设备在使用过程中应竭力避免铝合金在锈层下工作。     

Application of CFD Methods for Modelling in Air Pollution Problems: Possibilities and Gaps

Different urban air pollution problems deal with complex structure of air flows and turbulence. For such problems the Computer Fluid Dynamics (CFD) methods become widely used. However, this approach despite a number of advantages has some problems. Experience of use of CFD tools for development of models and suggestions of their applications for a local scale air pollution over a complex terrain and stable stratification are discussed in this paper, including: Topography and complex geometry: choose of the co-ordinate system and computer grid; Turbulence closure for air pollution modelling: modified k- model for stable stratified ABL; Boundary conditions for vertical profiles of velocity for stable-stratified atmosphere; Effects of the radiation and thermal budget of inclined surfaces to dispersion of pollutants; Artificial sources of air dynamics and circulation.Some examples of CFD applications for air pollution modelling for a flat terrain, mountainous area, mining open cast and indoor ventilation are discussed. Modified k- model for stably-stratified ABL is suggested. Due to the isotropic character of the k- model a combination of it in vertical with the sub-grid turbulence closure in horizontal can be more suitable for ABL. An effective scheme of boundary conditions for velocity profiles, based on the developed similarity theory for stable-stratified ABL, is suggested. Alongside with the common studies of atmospheric dispersion, the CFD methods have also demonstrated a good potential for studying anthropogenic and artificial-ventilation sources of air dynamic and circulation in local-scale processes of air pollution.     

Mechanics Principle and Engineering Application of Split Layer and Bed Separation of Mining Overburden

<正>To control land surface subsidence caused the underground mineral exploitation and the catastrophic phenomena such as serious damage of buildings, waterbodies, cultivated lands, railways, bridges caused by land subsidence, bed separation grouting technology of overburden is put forward. To provide theoretical support for the technology, the characteristics and the mechanics mechanism of mining overburden from layer-split to formation of bed separation are studied. On the basis of elastic sheet board theory, calculation formula of rock sheet deflection is presented, and the mechanics criteria of the separation formation and the calculation formula of bed separation volume are set up. Finally, the applications and technics of bed separation grout technology of mining overburden to control land subsidence in china are introduced.     

重庆近11年大气混合层厚度研究

根据新闻颁国家标准ＧＢ／Ｔ１３２０１－９１的规定，计算了重庆地区近１１年大气混合厚度，分析结果表明，重庆地区大气混合层厚度有明显日变化和季节变化，大气稳定度是混合层厚度的主要决定因子。     

多级环流曝气技术处理工业污水的实验研究

在结构简单、占地面积小、氧利用率高的多级环流曝气小型实验装置上，对某种石油化工排放污水进行了生化处理性能实验。分别利用间歇和连续两种装置进行污水的处理，均得到了良好的试验结果。间歇实验探索了污水降解与系统中溶解氧的变化情况的对比，摸索出了两者之间的初步关系。连续实验表明，污水的停留时间在3-5h时，出水COD可以降到80mg／L以下。     

城市环境系统的权重分配

本文将多目标二级决策法用于城市环境系统的权重分配，对城中环境系统各要素及各要素的表征参数进行客观自动赋权，克服了环境质量评价中权重分配的主观随意性。该方法物理意义清晰，算法简便，具有较好的应用价值。     

旅游城市环境规划优化方法与应用研究(Ⅰ)不确定性多目标规划模型

以旅游城市环境系统的综合性、多目标性、动态性和不确定性的特征出发，提出用不确定性模糊多目标规划（IFMOP）模型来解决旅游城市 环境规划优化问题。通过建立旅游城市环境不确定性模糊多目标规划系统模型（IFMOPMTCE），使旅游城市环境系统的特性在模型建立和求解过程中得以充分反映，同时也有效地协调了环境经济等目标之间的矛盾与冲突，该研究为旅游城市环境规划工作提供了一种较为有力的工具。     

科研工作中科技情报检索的作用--浅谈应用国际联机情报检索的体会

科技情报检索是科研工作中的重要环节,也是科研成果评价的必要手段.课题研究必须了解国内外发展动态,进行可行性和经济效益分析.本文通过国际联机情报检索的两个应用实例,阐明了情报检索不仅提高了科研工作效率,而且在课题研究的方法、深度和广度、最终结果方面都能得到很大益处.