Effects of road network on vegetation pattern in Xishuangbanna, Yunnan Province, Southwest China

The paper presents the results of a case study carried out in Xishuangbanna, Southwest China, to examine the relationship between vegetation dynamics and road network extension. We find that lower level roads had more effects on vegetation patches. Minor roads, including Class IV and Class V roads, contributed most to regional landscape fragmentation while high level roads had larger effect on vegetation dynamics in road effect zone. Further, road classes have close relationships with village distribution, topography fluctuation and landscape fragmentation. Topography, however had no direct relationship with vegetation pattern.     

考虑禁行路线路网的最优路径求解

为了解决含有禁行路线路网中的最优路径求解问题．研究了含有装行路线路网的特点．建立了数学模型。通过路网转化法把含有禁行路线的路网转化为不含禁行路线的路网．降低了最优路径求解的难度。采用邻接结点关系矩阵和邻接结点权矩阵表达路网中结点和路段的拓扑关系，减少了路网的存储空间。用动态邻接结点关系矩阵和邻接结点权矩阵对经典的Dijkstra算法进行了改进，节省了计算机存储空间、提高了计算效率．并给出了基本算法。将所研究的路网转化方法和改进的Dijkstra算法应用于所研发的车辆诱导系统软件，并进行了实际测试。测试结果表明．府用该方法能够在含有禁行路线的路网中求解最优路径．且运算效率较高。     

Meeting mobility and air quality goals: Strategies that work

Recent federal legislation sets tough air quality goals for the nation but offers scant guidance to urban areas responsible for meeting those goals. Traditionally, transportation-related air quality policy emphasized cleaner vehicle and fuels technologies and alternatives to single-occupant vehicle travel such as car-pooling and mass transit. Analysis suggests, however, that meeting air quality goals will require the addition of policies to manage the growing demand for transportation. The introduction of market forces into transportation supply and demand decisions would support traditional transportation and air quality strategies, and produce additional mobility, air quality, and economic benefits. Recent transportation legislation offers states and localities the flexibility to meet mobility and air quality goals in an innovative, nontraditional manner. Drawing on theoretical analysis and recent empirical evidence we offer a package of measures for the consideration of state, and federal policy-makers.The authors are with the Office of Policy Analysis of the U.S. Environmental Protection Agency. The views expressed here belong solely to the authors. This paper does not represent the view of the US EPA or the policy of the United States Government. This paper was significantly improved by extensive comments from Bruce Schillo, and by suggestions from Michael Shelby, John Chamberlin (all of the EPA Office of Policy Analysis), Robin Miles-McLean (EPA Office of Mobile Sources), Allen Basala (EPA Office of Air Quality Planning and Standards), and numerous other colleagues. The authors are responsible for all errors and interpretations.     

国内外疏浚土综合利用现状对比分析*

采用国内调研、国外考察、查阅国内外文献等相结合的方法,对比分析国内外疏浚土综合利用的现状和特点,找出国内疏浚土综合利用存在的主要问题与差距,提出今后我国疏浚土综合利用技术的发展方向和重点。结果表明:我国疏浚土综合利用水平远落后于国外主要发达国家,当前影响我国疏浚土综合利用的因素除技术问题外,还存在认识理念、体制机制、法规制度建设和利益分配等非技术问题;今后我国疏浚土综合利用技术的发展方向和重点主要包括吹泥上滩新工艺、新型疏浚装备的研制和开发、疏浚土综合利用多样化处理技术、加强疏浚过程环境保护技术研究等。     

北京南站地区交通组织策略

随着社会经济的发展,汽车保有量的增加,由此引起一系列交通问题,这使得城市交通组织的地位也越来越重要.本文选取北京南站地区作为研究案例,通过对南站及周边区域交通状况的实际调研,分析南站区域路网中的主要车流流向,得到马家堡区域和陶然亭区域的交通组织形式不合理,并分析导致路网负荷不均的主要原因是交通标志;进而提出了南站地区合...     

动态教学在高职院《就业指导》课程中的应用

高职院的《就业指导》课程既强调职业在人生发展中的重要地位,又关注学生的全面发展,为了提高教学效果,达到教学目标,《就业指导》课程应采用动态的教学模式,做到教学内容的遴选上应与专业课程互动、教学实践的活动中应与企业等用人单位的互动、教学方式的运用上应重视师生互动、生生互动。     

试论当前“招工难”和“就业难”现象的原因及对策

文章以当前我国人力资源市场上出现的“招工难”与“就业难”现象为研究内容,以民营企业与高职毕业生为研究对象,分析了这一现象产生的原因,并提出解决这一矛盾的几点建议。文章指出民营企业要提高人力资源管理水平,通过“双元制”实现人才战略规划;高职院校要加强就业指导,帮助学生树立正确的择业观,借鉴“双元制”职教模式,保证高素质高...     

认清形势 抓住机遇 促进城市公共交通健康发展——在中国城市公共交通协会第四次会员代表大会上的讲话

“十二五”期间,中国城镇化处于转型发展的关键时期,城市交通发展模式及发展方向问题值得认真思考和研究.介绍了美国和欧盟两种全球最具代表性的城市交通模式,指出要避免犯美国城镇化的错误,就必须充分重视城市公共交通对城市发展所起到的决定性作用.提出要抓住两个机遇大力发展公共交通,优先把城市空间资源分配给公共交通,并与其他各种绿...     

高架人行步道建设模式及适用性

针对近年来大规模建设的高架人行步道存在的问题,开展建设模式及适用性研究.将高架人行步道建设模式归纳为高架平台、路侧式空中连廊、点状天桥三种类型,分别以上海世博轴、香港空中连廊、上海市陆家嘴明珠环天桥为典型案例,重点分析每种模式的优缺点和适用条件.总结了高架人行步道与建筑物的连接方式及其适用条件和需要重点解决的问题.以上...     

一种基于并发奖赏蚁群系统的A*算法

为优化出行者在动态路径诱导系统中进行路径选择,提出一种基于并发奖赏蚁群系统的A*算法,利用A*算法的成熟性和蚁群算法的动态性,用蚁群算法对A*算法估价函数f(x)=g(x)+h(x)中的h(x)进行研究,考虑了交通路况中的各种动态因素,使A*算法具有动态性;为了提高算法的效率,基于在最优路径附近往往存在更优路径这一原理...