Life cycle assessment of energy from waste via anaerobic digestion: A UK case study

Particularly in the UK, there is potential for use of large-scale anaerobic digestion (AD) plants to treat food waste, possibly along with other organic wastes, to produce biogas. This paper presents the results of a life cycle assessment to compare the environmental impacts of AD with energy and organic fertiliser production against two alternative approaches: incineration with energy production by CHP and landfill with electricity production. In particular the paper investigates the dependency of the results on some specific assumptions and key process parameters. The input Life Cycle Inventory data are specific to the Greater London area, UK. Anaerobic digestion emerges as the best treatment option in terms of total CO₂ and total SO₂ saved, when energy and organic fertiliser substitute non-renewable electricity, heat and inorganic fertiliser. For photochemical ozone and nutrient enrichment potentials, AD is the second option while incineration is shown to be the most environmentally friendly solution. The robustness of the model is investigated with a sensitivity analysis. The most critical assumption concerns the quantity and quality of the energy substituted by the biogas production. Two key issues affect the development and deployment of future anaerobic digestion plants: maximising the electricity produced by the CHP unit fuelled by biogas and to defining the future energy scenario in which the plant will be embedded.     

基于安全行车的高速铁路夕发朝至列车开行方案编制优化

针对京广高速铁路,研究基于安全行车的夕发朝至旅客列车开行方案优化问题。结合目前已有研究成果,对单线行车、转线2次、转线1次、等线运行四种开行模式适应性和安全性进行分析。分析列车运行径路,在安全行车、运行时间与停站要求的约束下,确定列车开行模式,以最佳旅行时间为目标函数,建立数学模型,得出优化的夕发朝至列车开行方案。根据开行方案和现有运营经验分析列车运行条件,提出高速线采用(8~10)min追踪间隔,既有线采用(10~12)min追踪间隔,速度系数为0.8,以最大化利用通过能力为目标,编制符合实际条件的列车开行方案。     

Assessing environmental factors in red spruce (Picea rubens Sarg.) growth in the Great Smoky Mountains National Park, USA: From conceptual model, envirogram, to simulation model

This study provides a method for assessing a multiplicity of environmental factors in red spruce growth in the Great Smoky Mountains National Park (GSMNP) of Southeastern USA. Direct and indirect factors in the annual growth increment are first organized into a schematic input-output envirogram (ARIRS), and this information is then used to construct a simulation model (ARIM). The envirogram represents a structured conceptualization of most environmental factors involved in growth, as developed from relevant literature. This interdisciplinary synthesis distinguishes direct vs. indirect factors in growth and takes account of the systems ecology concept that indirect factors may be as important as or more important than direct ones in regulating growth. The ARIRS envirogram summarizes hierarchically organized, within- and cross-scale, local-to-global interactions, and its construction makes it obvious that growth is influenced by many cross-scale spatiotemporal interactions. More research on genecology is still needed to clarify the role of phenotypic plasticity and adaptive capacity in nutrient cycling, global change, and human disturbance.     

Efficient thinning regimes for Eucalyptus fastigata: Multi-objective stand-level optimisation using the island model genetic algorithm

A stand-level optimisation problem formulated to determine a set of efficient thinning regimes satisfying two objectives, i.e. value production for sawlog harvesting and volume production for a pulpwood market, was demonstrated for a Eucalyptus fastigata trial in Kaingaroa Forest, New Zealand. Genetic algorithms were used to estimate the set of efficient thinning regimes (i.e. regimes that occur when it is not possible to increase the achievement of one objective without reducing another) known as a Pareto frontier. Each thinning regime specified a unique combination of initial planting density; frequency, timing and intensity of thinning; final crop number; and rotation length. Specifications for the “best” regime in the Pareto set (i.e. the one that satisfied a balanced trade-off between value and volume production) were similar to those recommended through professional judgment based on pooled long-term field observations from different eucalypt species grown throughout New Zealand. The advantage of Pareto optimality was the ability of not only identifying a unique thinning regime, but equally efficient regimes each providing a different combination of value and volume production. Research on this approach has the potential of being applied to other forest sites, providing there is sufficient re-measurement data to reflect stand growth dynamics.     

基于气象预测数据的中国洪涝灾害危险性评估与预警研究

基于自然灾害风险理论,借助GIS强大的空间分析功能,采用归一化和层次分析法,对中国全国范围尺度进行了洪涝灾害危险性评估。通过对洪涝灾害危险性因子分析,分别提取当天降雨量、前3 d降雨量、地形高程、地形标准差、河湖网络等因素作为评估因子,提出了各因子危险性指数计算方法,以及全国洪涝灾害危险性指数计算模型公式。根据统计分析危险指数的最小值、最大值,结合历史灾情,利用阈值分割法确定了风险等级分割值分别为0.3、0.45及0.6,将洪涝灾害等级划分为高风险、中风险、低风险与无风险四个等级,从而建立了类似于天气预报模式的全国洪涝灾害危险性评估模型,并以2010年8月22日为例进行了洪涝灾害危险等级评估的实际应用。最后,基于洪涝灾害的危险性评估的结果,结合危险区内人口分布、交通设施等基础数据,生成相应的预警产品。对可能发生的洪涝灾害发出预警与预测,为危险区人们乃至相关政府管理部门采取有效的防灾、减灾措施提供参考依据。     

地铁车厢纵火模拟试验火灾特性研究

在考虑人为恐怖袭击行为情况下,采用地铁车厢实体模型研究了地铁车厢在纵火情况下的火灾场景特性,得出了地铁车厢在模拟火灾中的热释放速率、烟气浓度、温度、烟密度的变化规律。试验结果表明,一节车厢最大热释放速率为5MW左右,如果两侧沙发同时引燃,其最大热释放速率可达10MW。在纵火试验中,火灾发生、发展和蔓延速度明显较快,燃烧较猛烈,高峰瞬时释放出的CO、CO2浓度及试验过程中的总浓度明显较高;NO、SO2、HCN集中在瞬间释放出来而造成瞬时浓度较高。烟气主流是沿着而不贴着屋顶向外蔓延的。因此火灾危险性很高。     

GIS和环境管理信息系统建设

结合地理信息系统的环境管理信息系统结构和功能形式，以贵阳市的大气环境管理信息系统建设为例，具体阐述了GIS基本功能应用，分析认为，深入结合地理信息系统与环境模型，才能促进环境管理信息系统向“决策支持”型和“专家”型方向发展，同时，环境信息的收集方式、共享程度和二次开发深度也将受到深刻的影响。     

中美环境影响评价制度若干问题比较

比较中国与美国环境影响评价制度的法律依据，评价范围，评价者与评价内容，中美环境法中均规定了该项制度、但美国法院判例也成为重要依据；与中国不同的是，美国环境影响评价之评价对象的唯一限制条件是“对人类有重大影响”，公众参与原则在美国环境影响评价制度中贯彻较好，美国环境影响报告书包括真实可行的替代方案。     

采掘行业环境影响评价制度存在问题的探讨

环境影响评价是环境管理的重要组成部分,为我国的环境管理决策提供重要依据。但在实际工作中,我国的环境管理工作仍然存在一定的问题。本文结合采掘行业的特点,分别从法律层面、设计层面和环境影响评价层面等三个方向进行分析,结合发现的问题提出建议,力求从不同的角度完善相关制度和技术要求。从而使采掘行业的环境管理能全面涵盖采掘行业开发过程,最大程度地减少采掘行业开发过程中的环境影响,完善采掘行业环境影响评价制度,对我国采掘行业生态环境的改善及环境影响评价法制建设起到一定的借鉴意义。     

汽车排放控制系统的设计策略探讨

简要介绍汽车排放污染物种类及其对人体的危害,阐述了现有汽车排放控制的技术措施,分析了汽车排放后处理技术存在的主要问题,提出汽车排放控制系统的设计方案,并对方案的可行性进行了分析研究.