基于Fluent的闭合环型缺氧反应器构造优化

为提高闭合环型缺氧反应器混合效果,选用基于Fluent软件的三维RNG k-ε紊流数学模型对闭合环型缺氧反应器进行流场模拟,以池底可能淤积面积比例作为混合效果的评价标准,分别从导流直墙长度、导流墙偏心距离及水下推进器偏置等3个方面对缺氧池的系统构造的最优设置进行研究。结果显示,在相同推进器功率下,导流直墙长度2.0 m为佳,导流墙偏心距离0.5 m为佳,推进器向内偏置0.5 m为佳。该研究方法及其结果可以作为闭合环型缺氧反应器的设计依据,具有较佳的技术参考价值。     

The dynamics of landfill diversion: Economic drivers, policy factors and spatial issues: Evidence from Italy using provincial panel data

Waste disposal is an issue that is becoming increasingly important in policy terms in the European Union, and in Italy, a country showing strong geographical heterogeneity in waste management. This paper analyses the process of decoupling/delinking between economic growth and landfilling trends in a framework where economic, policy, geographical elements and spatial issues are all considered as drivers behind the phenomenon. We exploit an original and very rich provincial panel dataset over 1999–2005 for the 103 Italian provinces. Evidence shows that the observed ‘absolute’ decoupling between economic growth and landfilling is driven by a mix of structural factors. Among the main factors, population density, more than the provincial income level, emerges as a crucial driver: local opportunity costs and landfill externalities matter in shaping waste policies and local commitment to a transition away from landfilling of waste (landfill diversion). However, not only structural factors are relevant. If on the one hand landfill taxes are not a significant driver of the phenomenon, waste management tools, such as separated collection for recycling, and the tariff system connected to waste services, bring about significant effect on the amount of landfilled waste. Moreover, regarding the analysis of spatial interrelations across provinces, we note that the presence of incinerators in nearby provinces increases landfill diversion, due probably to free riding behaviour or intra-provinces ‘agreements’ on waste management; this is not true for nearby landfill sites, that cause for a given province a strong lock in effect. Future research could strengthen the analysis of policy effectiveness at regional level, focusing on policy endogeneity, and the full investigation of spatial correlations in waste disposal performances.     

上海制造业产业转移实证研究

区域产业转移是区域经济发展到一定程度后的必然进程。随着资源环境承载压力增加和要素成本不断提升,上海面临产业发展的战略调整期,其中制造业转移是重要部分。通过构建区位熵指标,分析上海制造业转移的必要性和可行性,同时比较安徽、江西和湖北三省区位熵数据,论证各区域在承接产业转移上的比较优势,从而明确上海制造业转移的去向,最终促进上海和三省的区域产业结构升级,加快区域经济发展。     

导流栏杆设置对地铁岛式站台人员疏散的影响分析

为研究导流栏杆设置对地铁岛式站台人员疏散效率的影响,选取不同出口分布类型的地铁岛式站台为研究对象,基于BuildingEXODUS软件进行数值模拟,分析导流栏杆设置对不同出口分布类型地铁岛式站台人员疏散的影响.研究结果表明:A型站台在设置导流栏杆后,人员疏散时间均有所增加,导流栏杆设置长度为2,4 m时,人员疏散时间增...     

跨国界河流、跨流域调水与我国南水北调的基本问题

跨国界河流常是当今国与国水资源矛盾与冲突的发源地。在水资源空间分布不均衡背景下,跨流域调水是解决地区性水资源短缺的有效途径之一;然而,它同时也导致一系列社会经济与资源环境等问题。本文论述了主要跨国界流域中有关国家围绕水资源展开的矛盾与冲突,谈判与妥协。     

城市排水系统在水污染防治中的作用

本文介绍了城市排水系统的组成、分类和功能,通过介绍目前国内外城市的排水体制,对比了合流制和分流制的优缺点,并重点对雨污分流排水系统存在的问题、改造措施以及雨污分流效益分析进行了详细的介绍,最后指出城市排水系统在水污染防治中的作用和发展前景。     

北京市排污结构现状分析与对策研究

近年来,由于经济的迅速发展,北京地区水污染日趋严重,降低了水资源的使用价值,使本已严峻缺水的形势进一步恶化,极大地制约着首都社会经济及城市的发展。本文以１９９１年为报告期,采用污水直接排放系统、污水完全排放系数、ＣＯＤ直接排放系数、ＣＯＤ完全排放系数等指标对本市行业排污结构的现状进行了全面的分析和讨论,提出了相应的对策与建议,为改善本市水环境状况,缓解水资源短缺的压力,协调本市水环境与经济发展的关     

蒋家沟下游泥石流导流堤冲决原因及防治对策

河床逐渐淤高,主沟槽流势变化及泥石流规模是1999年9月蒋家沟下游泥石流导流堤溃决主要原因,在分析研究基础上提出相应防治对策。     

Human urine as a source of alternative natural fertilizer in agriculture: A flight of fancy or an achievable reality

Organically agricultural products are gaining popularities through out the world as it gives the consumer satisfaction with a basket of safer and better trusted foods. It is also well established that intensive conventional agricultural practices can introduce contaminants into the food chain with adverse affect on environment. However, organic agricultural practices give an alternative environmental friendly sustainable agriculture among the farmers. Beside this fact, organic crops contain fewer nitrates, nitrites, pesticide residues and trace elements than conventional crops. Even though, in organic systems generally have 20% lower yields than conventionally produced crops. One of the major constrains of organic farming is decrease of raw organic matters to prepare compost. Therefore, scientists are looking forward for different organic sources which are plenty in nature and available at little-to-no cost. Human urine is one of them, and has been gaining popularities as a raw material for organic cultivation. However, several important merits and demerits of application of human urine are needed to be addressed in agriculture.     

基于模糊综合分析法的引调水工程水质响应关系分析

为提升引调水工程的环境改善效果,须对水体的自身连通水平、水质现状、水环境主要影响因子进行分析。以太湖流域跃进联圩为研究对象,利用图论连通度理论对研究区域静态基流连通性进行评价,探索圩内水系连通性的空间差异及变化特性。同时,开展短期引调水实验,结合模糊综合分析法评价引调水带来的圩内水质变化情况及规律,研究圩内水环境和水系连通性的响应关系。结果表明,模糊综合评价法在引调水环境改善分析中具有适用性,可实现对圩内各监测点位水质变化的全面分析;水体流动性是影响圩区内水质的重要环境因素,高锰酸盐指数是导致圩内水质恶化的主要影响因子。引调水工程对圩区水环境具有一定的持续改善性作用,但对基流连通性较差的区域,改善效果有限。