QUALITY OF RUNOFF FROM MINNESOTA PEATLANDS: II. A METHOD FOR ASSESSING MINING IMPACTS1

ABSTRACT The impacts of milled peat mining on runoff quality in northern Minnesota were determined using a multiple watershed approach. The frequency distributions of water quality constituents were used to detect whether runoff from a mined bog differed from that of 15 unmined (control) bogs. Peat mining increased water temperature, suspended sediment, specific conductance and concentrations of acidity, iron, sodium, and nitrogen species, although drinking water standards were not exceeded (α= 0.05). The method presented may be applicable for other nonpoint pollution investigations.     

新形式下工业废水BOD_5稀释倍数的计算

推导了 BOD5稀释系数的量值关系 ,得出 BOD5稀释系数与样品的可生化性成正比 ,与稀释后水样的耗氧量成反比 ,并据此进一步分析了如何对样品的可生化性和稀释后水样的耗氧量进行预期。在此基础上从实际出发 ,根据工作经验简化和优化了稀释倍数的计算 ,达到提高测定准确度 ,降低劳动强度的目的     

Spatial based compromise programming for multiple criteria decision making in land use planning

Today, competing land use is continuing to occur in many developed regions. In the Agricultural Development Zone of Western Sydney Region, which is characterised by complex landscape patterns, land use competition is widespread. From a land use planning perspective, identification of suitable locations for a given type of land use is necessary for decision makers to formulate land use alternatives in different locations, based on existing land potential and constraints. For such a region, use of a simple method that implements a categorical system and considers only inherent land characteristics in the analysis is often inadequate to arrive at an optimal spatial decision. The primary aim of this paper is to develop spatial modelling procedures for agricultural land suitability analysis using compromise programming (CoPr) and fuzzy set approach within a geographical information systems (GIS) environment. Five main sets of spatial data for use as decision criteria were developed by using fuzzy set methodology: a land suitability index (LSI) for maximising the land productivity objective; an erosion tolerance index (ETI) for minimising the erosion risk objective; a runoff curve number (CN) for maximising the water discharge regulation objective; an accessibility (RP) measure for maximising the land accessibility objective; and the proximity to water body (WP) for minimising the water pollution objective. An L _p -metric was used in the analysis utilising different strategies with representative indices ranging from a situation where full tradeoff among criteria occurs to a noncompensatory condition. Different weighting combinations were also applied, and decision analysis was carried out by using values ranging from 0 to 1.0, where 1.0 is considered as an ideal point. The CoPr model demonstrated in this paper yielded a promising result, as several different techniques of sensitivity analysis show reasonably good results. Likewise, an overlay of that result with the present land use/land cover indicates a good corresponding spatial matching between existing land use (orchard and cultivated land), and the cells (land parcels) classified as the best in CoPr. The results are amenable to various map display techniques, either using continuous values or by defining different cut off points in the data space within a raster GIS environment.     

抗震性能设计的发展

现行建筑抗震设计规范是以保证人的生命安全为基本目标进行抗震设防的,即在小震和中等强度地震作用下控制结构的损伤发展,而在罕遇地震作用下防止结构倒塌.然而,据此设计的建筑由地震所造成的使用功能丧失而震后恢复重建所需费用或所花费的时间可能大大超过社会和业主所能承受的限度.因此,未来建筑在多级水准设防地震下的设计需达到多级性能水准已形成共识.基于性能的抗震设计将发展形成未来抗震设计规范.综述了基于性能的抗震设计的最新发展状况,提出了它存在的问题及进一步发展的趋势.     

SOIL EROSION AND GROUND WATER POLLUTION TRADEOFFS FOR NONIRRIGATED FARMING SYSTEMS1

ABSTRACT: Traditional focus on reducing one environmental externality may cause another externality to increase. This article examines the environmental and economic costs of abating soil loss and (or) nitrate leaching through alternative optimal production systems in the nonirrigated farming systems of Northeastern Oregon. Models estimating soil loss and nitrate‐nitrogen leaching rates associated with current production processes, are linked to a Multi‐Objective Programming (MOP) model. The results show that site specific conditions influence the level of abatement expenditures and optimal production strategies to reduce soil loss and leaching rates. Moreover, while existing production strategies are effective in reducing soil loss at little cost, no strategies could be identified to reduce nitrate leaching rate on some soils.     

应用多导流筒气升式环流生物反应器处理化肥工业含氨废水

在天津××化工厂建立了一套反应器有效体积为80m3的低高径比、多导流筒气升式环流生物反应器处理化肥工业含氨废水的装置。针对影响生物硝化效果的影响因素气液比、水力停留时间进行了考察,得到了操作的优化条件气液比为50∶1,水力停留时间为5h。在此条件下,该装置对废水中的COD_(Cr)和NH4+-N的去除率分别在75%和98%以上,出水中COD_(Cr)<50mg/L,NH4+-N<10mg/L。     

天津表层土壤中多环芳烃的主要来源

用主成分分析和多元线性回归分析方法研究了天津3个不同空间区域表土中PAHs的来源及其相对贡献.结果表明:燃煤和炼焦是各区最重要的PAHs释放源.塘沽汉沽高值区尤其如此,其燃煤和炼焦二者合计占总排放贡献的79%,交通源仅占21%.市中心及近郊区交通来源上升到与燃煤来源相当的水平(约各占35%),此外,焚烧产生的PAHs也占很高比例(21%).农村低值区则呈现出更多多源特点;秸秆燃烧是本区独有的,约占总贡献的11%.根据源解析得到的结果与根据燃料用量和排放因子计算的排放结果有一定可比性.     

民航机组人员个体与组织匹配对安全绩效的影响——基于MOA模型的定性比较分析

人为因素成为当今航空飞行安全的最大隐患,针对人的安全科学管理至关重要.为进一步探索民航机组人员安全行为路径,寻求可能的行为管理切入点,将民航机组人员作为研究对象,以MOA模型(动机-机会-能力)为理论框架,应用模糊集定性比较分析方法,探究民航机组人员个体与组织两个层面的5个条件对员工安全绩效差异的多重并发复杂机制和因果...     

基于FAHP-MODM的矿井通风系统可靠性综合评价

为了提高矿井通风系统可靠性评价的准确性,结合模糊层次分析法和多目标决策理论对矿井通风系统可靠性进行综合评价。基于人-机-环-管理系统构建评价指标并确定评价策略,确定各指标主观权重和客观权重,利用线性加权法确定综合评价值并通过实例分析矿井通风系统各观测点的可靠性,对其进行优劣排序并得出可靠性等级。评价结果表明,FAHP-MODM可对矿井通风系统可靠性做出准确的评价。