Analysis of pollutant levels in central Hong Kong applying neural network method with particle swarm optimization

Air pollution has emerged as an imminent issue in modernsociety. Prediction of pollutant levels is an importantresearch topic in atmospheric environment today. For fulfillingsuch prediction, the use of neural network (NN), and inparticular the multi-layer perceptrons, has presented to be acost-effective technique superior to traditional statisticalmethods. But their training, usually with back-propagation (BP)algorithm or other gradient algorithms, is often with certaindrawbacks, such as: 1) very slow convergence, and 2) easilygetting stuck in a local minimum. In this paper, a newlydeveloped method, particle swarm optimization (PSO) model, isadopted to train perceptrons, to predict pollutant levels, andas a result, a PSO-based neural network approach is presented. The approach is demonstrated to be feasible and effective bypredicting some real air-quality problems.     

The collection of PM10 for toxicological investigation: comparisons between different collecting devices

A positive correlation has been established between increased levels of airborne particulate pollution and adverse health effects, the toxicological mechanisms of which are poorly understood. For toxicologists to unambiguously determine thesemechanisms, truly representative samples of ambient PM₁₀ are required. This presents problems, as PM₁₀ collecting equipment commonly employed, such as the Tapered Element Oscillating Microbalance (TEOM®), heat the inflow toexclude moisture or use fibrous filters, resulting in a PM₁₀sample that may have undergone significant chemical change on thefilter surface or is contaminated by filter fibres. Other systems(i.e. Negretti and Partisol) can successfully collect PM₁₀ without chemical alteration or filter contamination. Comparativecollections from Port Talbot, S. Wales suggest that TEOMs and Negretti/Partisol systems collect different PM₁₀'s; the principle difference arising from the TEOM's heating chamber, which precipitates water-soluble ions and volatilises some organic components. This results in both the mass and compositionof the PM₁₀'s being altered. Particle size distributionsfor Negretti and Partisol collections highlighted differences mainly attributed to different flow rates. The results of thiswork demonstrate that simple correlations between PM₁₀ massand adverse health effects are problematic. Furthermore, elucidation of the complex fractionation and chemical changes indifferent collectors is necessary.     

有机气溶胶的来源与形成研究现状

介绍了有机气溶胶来源与形成的研究现状,从有机气溶胶的化学组成特征、一次有机气溶胶的来源和二次有机气溶胶的形成机制论述其研究进展.一次有机气溶胶主要来源于烹调油烟、机动车排放、生物质燃烧、工业或民用燃油锅炉释放出的有机物,还有道路扬尘、沥青、刹车尘、轮胎屑、室外香烟烟雾、以及高等植物蜡、细菌活动和草本植物等.大气中的半挥发性有机物可通过物理和化学吸附形成二次有机气溶胶,一些挥发性有机物可通过气相化学反应转化为低挥发性的物质并形成二次有机气溶胶,其主要前体物是芳香族化合物,如苯、甲苯、二甲苯,以及烯烃、烷烃、环烷烃、萜烯和生物排放的非饱和氧化物.     

Bipolar charged aerosol agglomeration and collection by a two-zone agglomerator

ＩｎｔｒｏｄｕｃｔｉｏｎＢｅｃａｕｓｅｏｆｔｈｅｌｏｗｅｆｆｉｃｉｅｎｃｙｏｆｔｈｅｅｌｅｃｔｒｏｓｔａｔｉｃｐｒｅｃｉｐｉｔａｔｏｒ (ＥＳＰ)ｆｏｒｃｏｌｌｅｃｔｉｎｇｔｈｅｓｕｂｍｉｃｒｏｎｐａｒｔｉｃｌｅｓ ,ｔｈｅｅｌｅｃｔｒｉｃａｌａｇｇｌｏｍｅｒａｔｉｏｎｍｅｔｈｏｄｈａｓｌｅｄｔｏａｎｉｎｃｒｅａｓｉｎｇｉｎｔｅｒｅｓｔｉｎｒｅｄｕｃｉｎｇｔｈｅｅｍｉｓｓｉｏｎｏｆｔｈｅｆｉｎｅｐａｒｔｉｃｌｅｓ .Ｍａｎｙａｕｔｈｏｒｓｈａｖｅｓｔｕｄｉｅｄｅｌｅｃｔｒｉｃａｌａｇｇｌｏｍｅｒａｔｉ…     

混凝研究中的界面过程化学:IPF-颗粒物-水溶液的相互作用

仅以IPF 颗粒物 水溶液的相互作用为例 ,对混凝研究中二界面过程化学领域的进展加以介绍 .研究结果表明 ,经过预制的聚合铝在混凝过程中表现出较好的形态稳定性 ,而传统混凝剂则强烈地受溶液化学过程 ,尤其是溶液pH值的影响 .混凝剂水解聚合形态倾向于在颗粒物表面吸附沉积 ,而直接引发混凝作用 .单体形态则通过转化为聚合、沉淀形态起混凝作用     

大气微小颗粒物中汞的污染特性初步研究

采用分级采样器采集大气中微小颗粒物中的汞,用冷原子吸收测汞仪分析。结果表明,颗粒态汞浓度随粒径分布呈双峰型,2个峰值分别出现在粒径1.0μm和4.0μm左右,与水溶性离子,碳含量的粒径分布基本一致。PM_(1.6)、PM_(8)和TSP中颗粒态汞的浓度分别为0.150、0.273、0.429ng/m~3,汞的质量分数分别为3.75.1.09、1.07μg/g,高于背景参考值;结果还表明,颗粒态汞主要集中在细颗粒中。通过正态概率分布测算,PM_(1.6)、PM_(6)中汞主要来自于1个主体源;PM_(1.6)中汞的浓度与硫酸根离子呈显著性相关,而与硝酸根离子、氯离子则不显著相关:说明颗粒物中汞的主要来源可能与燃煤有关。     

膜生物反应器膜污染的水力学控制实验研究

叙述了膜污染是影响膜-生物反应器处理技术推广应用的关键因素，采用水动力学方法是控制膜污染的有效方法。在不同污泥浓度条件下。对不同曝气强度下膜污染的发展速率及其形成机理进行了试验研究，研究结果表明：对应于不同污泥浓度均存在一个经济曝气强度，其大小随污泥浓度升高呈线性增加，膜生物反应器在经济曝气强度条件下运行可控制膜污染的发展；并从理论上推导出一个临界污泥浓度，其值为5．15g／L。对应于临界污泥浓度，并且污泥絮体在膜面可形成比较稳定的动态膜，膜过滤压差上升的速率最慢，膜生物反应器在此临界污泥浓度条件下运行膜污染发展最为缓慢。     

聚电解质溶液中粘土颗粒的ζ电位

分别测定了 5种不同分子量和 5种不同分子链电荷密度的阴离子聚电解质高分子在钠蒙脱石粘土颗粒表面吸附前后粘粒的ζ电位 ;讨论分析了分子结构和体系环境对粘粒 ζ电位的影响以及聚电解质对粘土 -水分散体系的稳定作用。     

青岛地区大气气溶胶海洋因子贡献研究

本文对青岛地区大气气溶胶海洋因子的贡献进行了分析研究，得出以下结构：（１）复季受海洋影响要比冬季明显得多；（２）就质量浓度而言，ＩＰ（ｉｎｈａｌａｂｌｅ ｐａｒｔｉｃｌｅ）中的海盐源要高于ＴＳＰ（ｔｏｔａｌ ｓｕｓｐｅｎｄｅｄ ｐａｒｔｉｃｕｌａｔｅｓ）；（３）海洋影响的程度和离海边的距离有关。离海逾远，受海洋影响就逾小；离海连逾近，受其影响就逾大；（４）ＩＰ冬季海盐源为２％－４％，夏季为１０％－     

磁分离除尘的初步实验研究及其机理分析

对磁性粉 尘和非 磁性粉 尘进 行 了磁 分离 实 验研 究。结 果 表明 ，对 磁性 粉尘 ，磁 除尘 效 率可达９９ ％ 以上 ，而对非 磁性粉尘 ，通过粉 尘上磁， 磁除尘效 率可达９ ０ ％ 以 上