Multiple-pattern parameter identification and uncertainty analysis approach for water quality modeling

This paper presents a multiple-pattern parameter identification and uncertainty analysis approach for robust water quality modeling using a neural network (NN) embedded genetic algorithm (GA). The modeling approach uses an adaptive NN–GA framework to inversely solve the governing equations in a water quality model for multiple parameter patterns, along with an alternating fitness method to maintain solution diversity. The procedure was demonstrated through a coupled 2D hydrodynamic and eutrophication model for Loch Raven Reservoir in Maryland. The inverse problem was formulated as a nonlinear optimization problem minimizing the degree of misfit (DOM) between model results and observed data. A set of NN models was developed to approximate the input-output response relationship of the Loch Raven Reservoir model and was incorporated into a GA framework in an adaptive fashion to search for near-optimal solutions minimizing the DOM. The numerical example showed that the adaptive NN–GA approach is capable of identifying multiple parameter patterns that reproduce the observed data equally well. The resulting parameter patterns were incorporated into the numerical model, and a multiple-pattern robust water quality modeling analysis, along with a compound margin of safety (CMOS) method, was proposed and applied to analyze the parameter pattern uncertainty.     

Macro- and mesoherbivores prefer native seaweeds over the invasive brown seaweed <Emphasis Type="Italic">Sargassum muticum</Emphasis>: a potential regulating role on invasions

Herbivory has a strong impact on algal distribution, abundance and community structure and may influence the establishment and spread of introduced seaweed species. In this study, we assess the potential regulating role of herbivory on one of the most invasive brown seaweeds: Sargassum muticum. Multiple choice feeding experiments were conducted with 13 native seaweeds, S. muticum and 5 herbivore species from the Northwest, Southwest and South of Portugal. S. muticum was always the least or among the least preferred seaweeds and attained one of the highest growth rates of the tested seaweeds, with and without herbivores. The addition of herbivores increased the number of cases by 40% in which the invader had higher growth rates. Our results suggest that low grazing pressure on S. muticum by the recipient herbivore community may give the invader a competitive advantage over at least part of the native seaweed community, thereby contributing to the invasiveness of S. muticum along the Portuguese coast.     

矿区砷污染对土壤线虫群落结构特征的影响

对湖南省石门县雄黄矿区不同As污染程度土壤线虫群落结构特征进行了研究.共获得线虫27属,食真菌线虫滑刃属(Aphelenchoides)在3种土壤中均为优势属.食细菌和食真菌线虫分别为低As和中As土壤的优势营养类群,而植物寄生线虫为高As土壤的优势营养类群.低As和中As土壤的自由生活线虫成熟度指数(IM)和瓦斯乐斯卡指数(IW)显著高于高As土壤,但植物寄生线虫成熟度指数(IPP)和IPP/IM比值则表现出相反的趋势.可见,高As土壤的食物网受到As污染的干扰较大,群落环境质量较差.因此,土壤线虫群落结构对土壤质量或生态系统的变化具有很好的生物指示作用.     

黄土高原马栏林区辽东栎的种子产量

辽东栎种子产量对其种群更新和恢复具有重要意义.调查研究了黄土高原马栏林区天然辽东栎次生林的种子产量,结果表明.该区天然辽东栎次生林处于较成熟阶段,结实植株所占比例高且种子产量丰富.分析发现,辽东栎结实植株数目表现出密度依赖效应,即样地结实植株密度与辽东栎植株的大小呈极显著的负相关,而辽东栎结实植株比例与样地密度呈极显著的负相关.通过埘标准枝上发育良好种子和败育种子数目的分析发现,在植株水平受精胚珠数与其发育种子数呈极显著的正相关;单株理论种子产量与胸径呈极显著的线性关系,表明辽东栎个体大的植株产生更多的种子;而对不同结实枝条,其高度与受精胚珠数、败育种子数和发育种子数均呈饭显著的线性关系,表明传粉或光照可能起到重要作用.此外,阳坡辽东栎林结实植株比例显著低于阴坡,表明样地水平坡向对辽东栎林结实也有一定的影响.图5 表3 参19     

响应面法优化阴阳极同时作用电化学法处理染料废水

在自制电化学反应器中,以甲基橙模拟染料废水为处理对象,采用Box-Behnken Design响应面法研究了影响阴阳极同时作用电化学法处理染料废水的因素及其交互作用。实验得出各因素对废水脱色率影响的大小顺序为：电流密度> Fe³⁺浓度>Cl^-浓度。各因素之间的交互作用对废水脱色率影响的大小顺序为：电流密度和Fe³⁺浓度>电流密度和Cl^-浓度>Fe³⁺浓度和Cl^-浓度。优化结果表明：Fe³⁺浓度为1.02 mmol/L、Cl^-浓度为10.96 mmol/L、电流密度为11.52 mA/cm²时,最佳脱色率为94.67%。阴阳极同时作用电化学法对甲基橙去除效果显著。     

布袋除尘器脉冲喷吹电磁阀误动作原因剖析及传统矩阵控制电路的改进

分析一起布袋除尘器脉冲喷吹电磁阀控制系统故障原因 ,推导出脉冲喷吹电磁阀可能误动作的一般条件 ,并对传统矩阵控制电路进行改进     

长袋低压脉冲袋式除尘器在水泥立窑烟气除尘上的应用

比较了几种用于水泥立窑烟气除尘装置后 ,长袋低压脉冲袋式除尘器的优势凸现 ,对其在广州新华水泥厂实际使用出现的问题作了详细分析 ,并提出了解决办法     

爱护动物尊重生命--访国际爱护动物基金会中国代表葛芮女士

野生动物的保护工作在中国已日显重要和迫切,今年广东省出台《广东省野生动物保护管理条例》,其中就对食用野生动物这一陋习在法律上给予了限制,使食用野生动物的“美食家”望而生畏,也使打击野生动物盗猎和非法食用者这项颇具难度的工作有法可依,逐渐走上正规。同时,今年恰逢中国正式加入濒危动植物种国际贸易公约20周年,且各中小学校即将开展爱护动物行动周的活动。借此契机,本刊记者与国际爱护动物基金会中国代表葛芮就中国以及世界野生濒危动物保护的历史、现状以及在这方面的宣传教育情况进行了详细的对话。     

新型絮凝剂室内评价试验

通过对比国外的有机絮凝剂和无机絮凝剂复配使用情况,对钻井污水用新型絮凝剂一有机一无机复合絮凝剂ＷＢＹ进行了评价,结果证明该絮凝剂能经济、高效地处理钻井污水。     

煤炭生物脱硫正交实验研究

通过对取自城门山,杨桃坞,德兴和云南的嗜酸氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)的生理活性的研究比较,选取了氧化活性较好的德兴菌种做正交试验.应用正交试验的方法研究了浸出时间,煤浆质量分数,pH值和接种量这4个因素的组合作用对煤炭生物脱硫效果的影响.对试验结果进行极差分析和方差分析,结果表明各因素对脱硫效果的影响有很大差异.在所研究因素的水平范围内,浸出时间对煤脱硫效率的影响最为显著,影响率达到74.21%;pH值对煤脱硫效率的影响也很显著,影响率为16.80%;接种量对煤脱硫效率的影响较为显著的,其影响率仅为5.27%;煤浆质量分数对脱硫效率的影响率最低,仅为1.78%.通过对正交试验的实验结果的直接观察,极差分析和方差分析,获得了三个可能的最优方案.其中通过实验结果直接观察得到的最优方案的脱硫率可达63.80%.