北京市城市生活垃圾组分预测

研究了北京市1991-1999年城市生活垃圾组分及变化特点.发现食品的含量最大,其次是塑料和纸类.以20世纪90年代生活垃圾产量和组分数据为基础,建立了生活垃圾组分人工神经网络预测模型.以预测的生活垃圾产量为输入值,分别对6个不同区域2001年、2005年、2008年与2010年的生活垃圾组分进行了预测,并用类比法进行了修正.考虑到由于城市发展规划不同区域生活垃圾比例变化情况,最终计算出全市生活垃圾组分变化.结果表明,在未来几年内北京市城市生活垃圾组分中,食品含量较高,但其比例逐年下降,纸类与塑料垃圾有增加,灰土所占比例减少.     

人工湿地+生态塘处理农村生活污水工程实例

"人工湿地+生态塘"系统是一种投资少、建设运营成本低、工艺简单的新生态处理系统。采用人工湿地+生态塘工艺处理农村生活污水,监测数据表明该工艺成熟可靠,去除N、P能力强,出水各污染指标均能达排放要求,证明该工艺是一种适合农村污水处理的新型工艺,适合在农村推广应用。     

基于人工神经网络方法的河北省近海沉积物重金属污染综合评价

利用误差反相传播神经(BP)网络对河北省近海沉积物中的铅、镉、锌、汞、砷5种重金属元素的污染水平进行分析,利用自组织特征映射(SOFM)网络对上述重金属元素分布特征进行分类,通过分类与污染水平量化值的结合,进行综合评价。SOFM把52个沉积物样品分别划分为3、4、6类和9类。对比各种分类,分为3类的物理意义较明确,每个类别分别对应高中低不同的污染物浓度水平,差异显著、分类方式比较合理。通过此种分类可以判断河北省近海的沉积物重金属污染在不同海域存在一定的差别,整体上是离海岸越远,沉积物的重金属污染水平越高,距海岸较近的海域内,沉积物的重金属污染水平较低,但渤海湾内的重金属污染水平高于其他海域。     

利用神经网络技术对华东地区进行地震预测

用BP神经网络技术研究华东地区(29°～37°N,114°～124°E)地震时间序列的规律,在大量实验的基础上得出,对于华东地区当输入层节点数目为12、隐层的节点数为16、输出层节点数为1时可以得到较好的收敛结果。根据选取的参数采用两种方法对华东地区进行地震预测,结果表明利用BP神经网络处理华东地区的地震时间序列有较强的容错性,进而认为将该方法用于华东地区地震时间序列的短临预测有较好的效果。     

The Brown Trout Population at Loch Fleet Eight Years After Liming

At the start of the Loch Fleet Project in 1984, the Loch and the upper 7 km of its efferent stream were found to be devoid of trout (Salmo trutta) as a result of acidification. Following the liming treatments applied to the catchment, from 1986 the formerly toxic water quality conditions (pH ∼ 4.5, calcium ∼ 1 mgl^-1, elevated aluminium and heavy metal levels) were eliminated, and trout were reintroduced on two occasions, in 1987 and 1988. A total of 520 fish were stocked, at a combined density equivalent to 5.5 kg ha^-1. Surveys of the loch and stream populations were carried out annually until 1993 to monitor their development, using a range of techniques, including electrofishing, gill-netting, seine-netting, spawner trapping and mark-release recapture methods. Length and scale- analysis were used to investigate fish growth.

The trout population in Loch Fleet expanded rapidly as a result of natural spawning in the loch's main feeder stream, augmented by the use of an artificial spawning bed which was constructed at the loch outlet in 1990. in mid-1983 the stock density, estimated by mark-recapture census methods, had increased to 24.9 kg ha^-1. Poor recruitment in the years 1991-93, however, reduced the rate of expansion and resulted in a population comprising mainly older individuals. the poor recruitment in these years was not fully explained but was not caused by water quality and was most likely a result of fry washout by spring spates.

Fish growth rates were high initially and were estimated on the basis of the Elliott trout growth model to be optimal for the prevailing water temperature regime of the loch. By 1991, growth rates had fallen, probably as a result of competition for food, but showed signs of recovery towards the end of the study period in 1993, following the period of lower population densities of young fish.

Trout rapidly repopulated the loch's outlet stream after 1987 but have remained sparse and have shown no signs of spawning within most of the stream. Water analyses have shown that the liming of the Loch Fleet catchment has minimal impact on downstream waters when flows are high, so that potentially toxic acid episodes have not been prevented.     

塔里木油田克拉作业区利用人工湿地处理生活污水

利用土地处理系统进行油田生活污水的净化及应用技术,目前在国内尚未推广使用。结合塔里木油田克拉作业区的实际情况,从废水的资源化、生态建设意义和减缓风蚀等角度出发,阐明了人工湿地建设在干旱区的重要作用;从土壤和地下水环境质量及其变化趋势的角度,分析了利用人工湿地处理生活废水的可行性;并对其进行了相应的效益分析。经分析论证,人工湿地可以用于克拉作业区生活污水的深度处理,并在干旱荒漠区进行推广。     

海水法烟气脱硫排水水质的估算和分析

对烟气海水法脱硫的排水水质进行了定量估算,并讨论了工艺排水对附近海域水质的影响.     

LAKE WATER QUALITY ASSESSMENT FROM LANDSAT THEMATIC MAPPER DATA USING NEURAL NETWORK: AN APPROACH TO OPTIMAL BAND COMBINATION SELECTION1

Abstract: The concern about water quality in inland water bodies such as lakes and reservoirs has been increasing. Owing to the complexity associated with field collection of water quality samples and subsequent laboratory analyses, scientists and researchers have employed remote sensing techniques for water quality information retrieval. Due to the limitations of linear regression methods, many researchers have employed the artificial neural network (ANN) technique to decorrelate satellite data in order to assess water quality. In this paper, we propose a method that establishes the output sensitivity toward changes in the individual input reflectance channels while modeling water quality from remote sensing data collected by Landsat thematic mapper (TM). From the sensitivity, a hypothesis about the importance of each band can be made and used as a guideline to select appropriate input variables (band combination) for ANN models based on the principle of parsimony for water quality retrieval. The approach is illustrated through a case study of Beaver Reservoir in Arkansas, USA. The results of the case study are highly promising and validate the input selection procedure outlined in this paper. The results indicate that this approach could significantly reduce the effort and computational time required to develop an ANN water quality model.     

耦合式盐平衡模式下工业废水零排放的研究

本文根据首钢京唐钢铁公司的内外部条件,并结合首钢实施生产废水零排放的运行经验,提出耦合式盐平衡模式,以海水淡化为基础,以分质供水为手段,从而实现了工业用水的零排放,并从理论上分析了不同条件下耦合式系统的运行工况。     

AN ENGINEERING ECONOMIC ANALYSIS OF A PROGRAM FOR ARTIFICIAL GROUNDWATER RECHARGE1

This study describes and demonstrates two alternate methods for evaluating the relative costs and benefits of artificial groundwater recharge using percolation ponds. The first analysis considers the benefits to be the reduction of pumping lifts and land subsidence; the second considers benefits as the alternative costs of a comparable surface delivery system. Example computations are carried out for an existing artificial recharge program in Santa Clara Valley in California. A computer groundwater model is used to estimate both the average long term and the drought period effects of artificial recharge in the study area. For the example problem, the benefits of reduced average annual pumping lifts and reduced incremental subsidence are greater than the total costs of continuing the existing artificial recharge program. Benefits for reduced subsidence are strongly dependent on initial aquifer conditions. The second analysis compares the costs of continuing the artificial recharge program with the costs of a surface system which would achieve the same hydraulic effects. Results indicate that the costs of artificial recharge are considerably smaller than the alternative costs of an equivalent surface system. In evaluating a particular program, consideration should also be given to uncertainties in future supplies and demands for water as well as to the probability of extreme events such as droughts.