边坡变形时序非线性判定及混沌预测研究

以探讨边坡变形性质及混沌预测可行性为目的,基于混沌理论利用相空间重构技术对其变形时间序列进行混沌特征判定,试验显示变形系统具有混沌特性,可用混沌相关理论进行研究;基于混沌相空间重构技术,笔者构建了多种混沌预测模型进行混沌预计研究,分析各类模型的工程实际应用效果;针对单次监测时序预测精度较低的问题,提出累加时序预测方案,训练结果显示,短期预测精度变形累计值基本控制在5%以内,高程值预测相对误差均低于1%,预测精度较高,可以用于工程实际。     

我国南方冰雪灾害的特征与城市救灾对策研究

在对2008年初中国南方所发生的冰雪灾害的损失、影响和成因进行分析的基础上,指出该次灾害具有受灾范围的全面性、灾害过程的发展性和救灾行动的艰难性等特征,阐明冰雪灾害在城市会造成停电停水、交通瘫痪和通讯中断等严重灾情,进而引发断油断粮、物价飞涨和人心恐慌等综合性灾害。通过冰雪灾害对城市救灾行动的总结,指出冰雪灾害给城市政府的深刻启示在于城市规模的急速扩张必须同时加强防灾救灾的软硬件建设,并提出城市必须采取持久开展防灾救灾知识宜传教育、大力加强防灾救灾基础设施建设、科学制订各类灾害的专业性应急预案和努力构建协同联动救灾机制等对策,有效提升城市应对灾害的能力,减少灾害造成的损失。     

城市生态安全多层次灰色综合评价

从城市生态安全的基本内涵出发,根据压力(pressure)-状态(state)-响应(response)模型,从生态系统压力、生态系统状况、生态系统响应3方面构建一个4层次的城市生态安全评价指标体系,运用灰色系统理论,构建了城市生态安全多层次灰色综合评价模型,并结合实例进行计算。评价结果与实际情况基本相符,表明该模型能有效地利用评价指标的信息,所给出的综合评价值既能用于描述所评价城市的生态安全状况,亦可对不同城市的生态安全状况进行比较,对更加科学合理地评价城市生态安全状况具有参考价值。     

城市燃气管道事故应急抢修方案的决策分析

通过对近年来的城市燃气管道事故抢险统计数据的分析与研究,管道事故抢险方案的选择存在着很大的主观性和片面性.为了克服应急抢修方案的种种局限,笔者应用模糊综合评判方法建立了城市燃气管道事故应急抢修方案评价选择模型;考虑可靠性、抢修时间、事故损失、抢险费用、社会影响及政治影响等6类影响因素来评判抢修方案的优劣,可以科学合理地选择最佳的管道事故应急抢修方案,达到经济合理、快速可靠的目的;实例验证,评判模型对城市燃气管道事故抢险具有重要的现实意义和参考价值.     

Scenario-visualization for the assessment of perceived green space qualities at the urban-rural fringe

The provision of green space is increasingly being perceived as an important factor for quality of life. However, green spaces often face high developmental pressure. The main objective of this study is to investigate a prospective approach to green space planning by combining three-dimensional (3D) visualization of green space scenarios and survey techniques to facilitate improved participation of the public. Aside from the ‘Status quo’, scenarios ‘Agriculture’, ‘Recreation’, ‘Nature conservation’ and ‘Wind turbines’ are visualized in three dimensions. In order to test responses, a survey was conducted both in print format and on the Internet. Overall, 49 different visualizations that belong to one of the scenarios were available in the survey and were rated according to the perceived esthetic, recreational and ecological values.The highest rated scenes include vegetation elements such as meadows with orchards, single trees, shrubs or forest. The least attractive scenes are those where buildings are highly dominant or where there are no vegetation elements.Based on the ratings for the individual images and on the corresponding scenarios, our study shows that there is high potential for improving the existing landscape. All suggested changes are either rated about equal to or considerably higher than the status quo, with the scenario ‘Nature conservation’ receiving the highest scores.     

The importance of differentiating urban and rural phenomena in examining the unequal distribution of locally desirable land

Previous research addressing the unequal distribution of locally desirable land (LDL) has mainly ignored their associated environments (i.e., rural or urban). However, this study proposed a new framework that treats rural and urban regions separately. In rural areas, the LDLs included all public lands. In urbanized areas, the LDLs were defined as green open spaces. Potential inequities in the distribution of LDL were assessed with respect to socioeconomic characteristics of residents in the State of Georgia. Using US Census Bureau Data (2000), Census Block Groups (CBGs) adjacent to LDLs were compared to CBGs outside of LDLs on four socioeconomic variables (per capita income, occupation, education, and race) in urban, suburban and rural environments. Results showed that CBGs adjacent to LDLs were composed of statistically significant upper-class communities containing fewer blue-collar workers, more whites, and higher income and higher educated people in rural, suburban and urban areas.     

Thoughts concerning the economic valuation of landscapes

The incorporation of economic thinking into the valuation of landscapes is still relatively new. It is an approach that yields valuable new insights and can help with prioritizing the use of scarce resources to improve and/or preserve landscapes. This paper explores and discusses the uses and limitations of economic valuation of landscapes from market failure, policy process, and theoretical and philosophical perspectives.     

基于现代信息技术的城市灾害应急管理系统

城市灾害应急管理系统是一项复杂的大系统工程。本文着重从应急管理过程中的应急资源调配、应急预案制定等方面阐述了现代信息技术在城市灾害应急管理中的应用与优势。认为应急管理信息系统的建立目的不是为了预测和估算,而应是当灾害发生时,对已造成的灾情局面做出快速的辅助决策支持。基于此,利用SuperMapObject5.0,Visual Basic6.0,SQL Server2000等现代信息技术软件,以辅助决策、资源快速查询以及生命线管网易损处调查为目的,本文建立了一个局部地区灾害应急管理信息系统。系统的数据库建立更突出了为应急管理服务所需的基础信息、空间数据、应急预案和应急资源等信息划分方式;结合已有的震害预测理论和方法,开发了供水系统和交通系统的震害预测模块,事先为灾害应急决策提供可能的震害信息。系统的开发过程进一步证明了GIS在城市灾害应急管理中有着直观显示、容易操作、辅助准确决策等优势。     

上海城市灾害分析与减灾建设

随着人口越来越向城市集中,城市灾害日益引起人们的普遍关注,本文针对上海市的自然灾害和人为灾害现状,分析了这些城市灾害的主要特征及其潜在的致灾防患,并总结论述了上海市防灾减灾建设的措施和工作情况。     

中国城市建设用地集聚对利用效率的影响:机理、空间效应与分群差异

为探究城市建设用地集聚对城市建设用地利用效率的作用机理,文章基于2003—2017年中国278个地级及以上城市面板数据,通过构建多产出随机前沿生产函数模型测度城市建设用地利用效率,采用时间-空间双固定的空间杜宾模型探讨了不同程度的城市建设用地集聚对利用效率的影响机理与差异。结果表明:(1)从时空特征上来看,样本考察期内中国城市建设用地利用效率总体上呈稳步提升趋势,东部城市建设用地效率最高,西部次之,中部最低。(2)从全国维度的空间计量模型回归结果来看,城市建设用地集聚所带来的规模效应和外溢效应对城市建设用地利用效率具有改进作用,有利于利用效率进一步提升。(3)从不同城市建设用地集聚度分群回归结果来看,高集聚城市(东部发达地区)的直接效应显示随着城市建设用地集聚度的提高,利用效率也不断提高;间接效应中,建设用地集聚度的提高对周边城市的利用效率产生先带动后抑制的"倒U"形作用。低集聚城市(中西部欠发达地区)的直接效应和间接效应均显示,随着城市建设用地集聚的提高,其利用效率存在"先降后升"的"U"形曲线特征。可见,在城市发展的不同阶段,城市建设用地集聚对城市土地利用效率存在差异化影响。因此,中国城市发展应立足当前发展阶段特征,制定差别化的供地政策,促进城市建设用地集聚,针对性地提升区域要素利用效率,支撑经济社会进一步发展。