怠速工况下汽车使用乙醇汽油排放污染物的变化

对怠速工况下使用乙醇汽油汽车尾气中污染物进行了检测.结果表明,使用乙醇汽油后,汽车尾气中CO和HC浓度明显降低,平均下降率为56.9%和38.2%;NOx平均下降率为15.0%;CO2浓度平均增长率为5.04%;苯系物浓度明显降低,平均下降率在45.5%～53.1%;醛类的浓度增加明显,平均增长率在47.8%～293%;丙酮、丁酮的浓度增加,分别为16.6%和25.3%.     

Context and Systems: Thinking More Broadly About Effectiveness in Strategic Environmental Assessment in China

China is an illustrative—and extreme—case of the difficulties of balancing the pursuit of economic, social, and environmental objectives. In 2003 it adopted a form of Strategic Environmental Assessment (SEA) for its plans and programs (referred to here as PEIA) with the aim of moving towards greater environmental sustainability. The literature has explored primarily the issue of methods and legal procedures. This research contributes to the analysis of PEIA through a different set of interpretative lens. Drawing on recent developments in the theory and practice of SEA, I propose a conceptualization of SEA effectiveness that combines direct and incremental impacts, and a need for context-specific systems as a way to focus on the relationship between assessment, planning, and their context, and thus maximize effectiveness. This framework underpins the analysis of China’s experience, which I explore with the help of interview material and the literature. The result is an evaluation of the strengths and weaknesses of PEIA in terms of its purpose, assessment concept, process, and methods. The detailed analysis of six aspects of the context helps explain the origin of such shortcomings, and identify opportunities for its improvement. I conclude defining elements of a context-specific system for SEA that seeks to maximize the opportunity for incremental, as well as direct, effectiveness in China.     

机动车尾气排放检测方法对比分析

通过怠速、双怠速法对机动车尾气检测试验和数据对比分析表明,不同车龄段的电喷型轿车采用怠速法检测尾气达标率在73.3%～93.5%之间;双怠速法检测尾气达标率在40.0%～82.6%之间.不同车龄段的化油器型轿车采用怠速法检测尾气达标率在25.0%～57.1%之间;双怠速法检测尾气达标率在18.8%～57.1%之间.指出双怠速法对化油器车辆尾气控制同样有效果,双怠速法对筛选高污染车辆比怠速法更严格和科学.     

滑索张紧力的抛物线计算方法

滑索是游乐设施 ,属特种设备。它直接涉及到人的生命安全。滑索张紧力的正确计算是确保滑索安全运行的关键因素。笔者从悬链线标准线形出发 ,在抛物线曲线方程基础上 ,推导了滑索在无载荷和有载荷时滑索最大张紧力计算公式及索线长度 ,并给出了工程应用实例 ,所得结论和公式具有一定的工程应用价值 ,希望能够为滑索的设计和制造提供正确思路。     

车辆超限超载的危害性与治理对策研究

调研了我国公路超载的现状 ,分析了车辆超限超载对于损害公路和桥梁、危害交通安全、扰乱运输市场秩序、污染环境的危害性 ,探讨了超限超载屡禁不止的各种原因 ,指出了治理工作的艰巨性和复杂性 ;通过对美国、韩国、德国、日本、南非等国治理超限超载经验的研究 ,分析了超载中需要处理的几个重要关系 ,据此提出了我国应采取“广泛宣传、统一行动、多方合作、依法严管、把住源头、经济调节、短期治标、长期治本”的 8项对策。     

A research agenda for increasing safety belt use in the United States

On November 13-14, 2003, a symposium on high-visibility safety belt use enforcement in Raleigh, NC: (a) celebrated the 10th anniversary of North Carolina's Click It or Ticket program; (b) documented current knowledge regarding safety belt use; (c) proposed strategies to increase use further; and (d) discussed research to support these strategies.     

森林特殊火行为格局的卫星遥感研究

由于多变的天气条件,复杂的地形和植被分布,引起火行为格局的变化,借助GIS和卫星遥感技术,以1987年大兴安岭5．6大火为对策,进行火行为变化规律和火行为的时空格局研究,环境风对火行为具有决定性作用,大风期间火强度极高,过火区为火蔓延的廓道,较大的山脉对林火有阻隔作用,森林采伐改变可燃物连续性,可以改变火行为,人类扑火对大火作用不明显,小地形可产生不同火烧强度的细微结构。     

Study on convection and dispersion characteristics of dense gases in urban environment considering trees

Although several studies on the dispersion of heavy toxic gas released from ruptured tanks on vehicles during transportation have considered complex terrain such as urban buildings, the influence of trees on the flow field in urban areas during gas dispersion tends to be ignored. In this study, a Computational Fluid Dynamics (CFD) model was proposed to investigate the characteristics of gas release and dispersion from loaded vehicle in the urban environment. In this model, the tree crown was treated as a porous medium, and the influence of drag due to the crown was incorporated into the model by a momentum source term through a user-defined function. In this study, the dynamic characteristics of chlorine (Cl₂) dispersion under the conditions of building distribution, tree species and porosities were comprehensively analysed, to cover the influence of urban complexity, leaf density, and tree planting configuration. The results show that compared with flat terrain, the presence of urban buildings will prolong the dense gas retention time and increase the dangerous distance. It is found that the horizontal dispersion distance can increase by 63% and the isosurface of 25 ppm hazardous gas can increase by 130% with the introduction of buildings. Compared with the terrain with only buildings, the introduction of arbors or shrubs can result in a 147% or 359% increase in the maximum concentration. Also, trees will prolong the dispersion duration. It is also found that the higher the porosity, the less the wind blocking effect, and the weaker the ability of capturing gas. The wind field affected by arbores and shrubs are different in height, and arbores capture more Cl₂. Planting short shrubs around buildings can effectively reduce the spread of harmful gases.     

The use and effectiveness of the site of special scientific interest designation in the east midlands region of the nature conservancy council

This paper looks at the use and effectiveness of the Site of Special Scientific Interest designation in three counties in the East Midlands region of the Nature Conservancy Council, namely Nottinghamshire, Northamptonshire and Cambridgeshire. Using unpublished sources within the NCC an analysis is made of the SSSI system in practice since its inception in 1949. A number of findings relating to weaknesses in the designation and the operation of the designation system emerge. Each of these findings is discussed in turn with the presentation of the appropriate evidence from the county case studies.     

简易升降类机械式停车设备安全隐患探析

随着人们生活水平的提高,单个家庭购买多部汽车的情况在逐年增加,停车位一位难求的矛盾比较突出。住宅小区家庭用户购买的单个平面停车位向立体2个停车位拓展情况成为趋势。本文从防载车板坠落装置设置、同步检测装置、载车板升降过程中视线盲区三个方面分析其安全隐患,并有针对性地提出一些建议,旨在减少简易升降类机械式停车设备的安全隐患提供有益帮助。