SEQUENTIAL GENERATION OF STREAMFLOW1

ABSTRACT: An auto-regressive model has been developed for hydrologic data simulation. The model is computationally easier, parsimonious in number of model parameters and more stable in statistical characteristics than the existing auto-regressive model. The proposed model was used for synthesizing 10 sequences, each of 100 year length, of monthly flows for the river Beas. The statistical parameters were calculated using 49-year historical record for the river. The data was also synthesized using existing auot-regressive model. The synthesized sequences have been compared. The results indicate that the proposed model is as good as the existing auto-regressive model in preserving the mean and standard deviation of historical record. It is further shown that the proposed model requires less parameters than the auto-regressive model for simulation of long-term dependence.     

Waste Management in Guangdong Cities: The Waste Management Literacy and Waste Reduction Preferences of Domestic Waste Generators

A questionnaire survey was conducted in 2002 on 1365 households in two prefectural-level cities in the Pearl River Delta, Jiangmen and Zhongshan. Three groups of issues are covered in this paper: 1) waste management literacy, concerns, and public participation; 2) waste recycling practices and the potential for waste avoidance; and 3) public environmental literacy. This study confirms findings from previous surveys and provides new information on important issues such as imposing monetary charges on waste and environmental activities, littering, source separation programs (SSPs), and public participation and expectations in local waste management. Saving up recyclable materials for redemption in waste depots is commonly practiced in mainland China regardless of the level of development of a city, although at the household level, high-income families tend to place less value on the revenues to be gained from redemption than lower income groups do. Data from the previous and the present studies indicate that such voluntary but largely economically driven waste recovery behavior diverts at least 10% of the household waste from the waste stream. Although uncompensated SSP is less appealing in the two cities than compensated SSP, it was found that when the median per capita income of a city reaches RMB2000 per month, a high participation rate for uncompensated waste recovery is more likely to occur. Education and income levels are the chief factors affecting littering behavior and the potential for waste avoidance. Contrary to general belief, the local Chinese community is active in microwaste management. The concern, however, is over the inability of the grassroots bureaucracy to deal with rising expectations for waste collection services and neighborhood cleanliness.     

IMPROVEMENT OF LEACHATE PREDICTION THROUGH MUNICIPAL SOLID WASTE LAYERS1

ABSTRACT: Existing leachate prediction models over- or underestimate leachate generation by up to three orders of magnitude. Practical experiments show that channeled flow in waste leads to rapid discharge of large leachate volumes and heterogeneous moisture distributions. In order to more accurately predict leachate generation, leachate models must be improved. To predict moisture movement through waste, the one-domain water balance model HELP, and two-domain PREFLO, are tested. Experimental waste and leachate flow values are compared with model predictions. When calibrated with experimental parameters, the HELP model yields reasonable predictions of cumulative leachate flow and PREFLO provides estimates of breakthrough time. In the short term, field capacity has to be reduced to 0.12 and effective storage and hydraulic conductivity of the waste must be increased to 0.2 and 2.2 cm/s respectively. In the long term, a new modeling approach must be developed to adequately describe the moisture movement mechanisms.     

THE VALUE OF STREAMFLOW FORECASTING IN RESERVOIR OPERATION1

ABSTRACT: The value of streamflow forecasts in reservoir operation depends on a number of factors and may vary considerably. Assessment of forecast benefits is presented here for three specific systems. Statistical streamflow models of increasing forecasting ability are coupled with a recently developed stochastic control method in extensive simulation experiments. The performance of the system is statisticafly evaluated with regard to energy generation and flood and drought prevention. The results indicate that forecast benefits are system specific and may range from quite substantial to fairly minimal.     

流动注射--氢化物发生原子吸收法测定天然水中的丁基锡化合物

建立用流动注射--氢化物发生原子吸收法同时测定天然水中一丁基锡、二丁基锡、三丁基锡和四丁基锡化合物的方法.首先用NaBH4还原丁基锡化合物后冷凝富集、加热,氢化物根据沸点的不同依次解吸从而得到分离,由原子吸收法测定.本方法可测每升几十纳克(以锡计)的各种丁基锡化合物.     

孙虎地区烃源岩生排烃史模拟及结果分析

生排烃史是研究成藏过程的关键环节,本文在恢复埋藏史的基础上,通过建立生排烃史模型,模拟并编制各时期的生排烃强度等值线图并分析其生排烃史。结果表明,孙虎地区存在持续沉降型、早期沉降型和二次沉降型三种生排烃类型。沙三段至东营组沉积末期只在北区和前磨头洼陷中心有少量的烃生成排出;孔二段在沙一段沉积末期生排烃范围有所扩大,东营组沉积末期几乎扩展到全区。本区生排烃总量较少,属贫油区块。     

由通风网络结构数据自动生成通风网络图研究

通风网络图是矿井通风管理的一种重要图件.本文根据通风网络图的特点,介绍了一种由通风网络结构数据自动生成通风网络图的方法,并进行了开发实现和实践应用.     

浅析成都市生活垃圾焚烧发电的经济可行性

根据成都市生活垃圾性状和现有的工业基础及技术经济条件，对成都市建设生活垃圾焚烧发电厂的经济可行性进行了初步分析，指出上网电价为0．25元／千瓦时，政府对处置垃圾的补贴费为50元／吨，是经济可行的。     

氢化物发生-原子荧光法测定一次性餐具中砷

建立了一次性餐具中砷的氢化物发生－原子荧光测定方法，在选定的试验条件下，荧光强度与砷质量浓度在0μg/L－180μg/L范围内呈线性关系，相关系数0．999 3，溶液检测限0．5μg/L，回收率96％－101％。     

铅染毒导致小鼠DNA损伤与氧化损伤

为了研究亚急性铅暴露对小鼠的遗传毒性及氧化损伤的诱导,将不同剂量的醋酸铅对小鼠隔日灌胃4周,用彗星实验检测其外周血淋巴细胞DNA损伤,并测定肝组织中活性氧自由基(ROS)的水平和脂质过氧化主要终产物丙二醛(MDA)的含量.结果显示,随染铅剂量的增加,小鼠肝线粒体中的ROS水平明显升高,染铅剂量为500 mg·kg-1组与对照组相比有显著性差异;肝MDA含量以及淋巴细胞尾长和尾相显著增加,染铅剂量为50、100、500 mg·kg-1组与对照组相比均有显著性差异;MDA与尾长和尾相的变化趋势一致.诱导产生自由基并导致脂质过氧化作用增强及DNA损伤是铅引起机体损伤的主要机制之一.