格宾网箱覆绿功能反滤层优化设计研究

格宾网箱应用于边坡工程时具备护坡、覆绿及材料就地利用等多种特点。为了保证格宾网箱中的植被能够稳定存活,并且防止强降雨条件下植被土颗粒的流失,需对格宾网箱填充物进行反滤层的优化设计,从而实现绿色生态护坡的目的。依托北京冬奥会张家口赛区正在实施的“科技冬奥”项目,在模拟当地最大降雨强度条件下,采用自行设计的试验装置开展了反滤层的防冲刷试验,探究反滤层层数、厚度和反滤料粒径对反滤层防冲刷效果的影响,最终确定了格宾网箱覆绿功能反滤层的优化设计。试验结果表明：反滤层层数设置为两层,上下层厚度均为100 mm且上层碎石粒径小于20 mm、下层碎石粒径为20~100 mm时,反滤层的防冲刷效果最佳。     

基于结构安全的水工隧洞施工仿真系统研究

水工隧洞施工情况复杂,目前的施工仿真计算大多只考虑开挖而缺乏衬砌和灌浆因素,故没有体现隧洞完整的施工过程;施工动态仿真一般根据仿真结果采用预制动画的形式实现,其实现过程复杂,模型不易修改,隧洞施工过程中结构状况例如围岩稳定、锚杆等支护的安全难以直观地确定。考虑隧洞施工各个工序结合系统仿真的方法,调用开挖、衬砌及灌浆的CYCLONE模型得到更为准确的进度计划,基于BIM技术实现施工动态可视化。针对目前较少涉及隧洞结构安全与进度计划耦合仿真,提出基于映射概念与反馈技术的隧洞施工期结构安全仿真方法,基于二次开发技术与数据库技术,采用VB.NET+PYTHON语言编制了一套水工隧洞施工仿真系统,实现与工程施工进度相结合的结构安全判断,为工程师提供良好的数据支持。     

斜板沉淀池前配水渠的数值模拟及结构优化

针对配水渠出水优化措施单一、优化效果欠佳的问题,运用CFD软件,采用Realizable k-ε湍流模型对其流速场进行数值模拟,探究了进口宽度（b）和配水渠宽度（B）变化时出水均匀度最优的配水渠长度（L）,并优化了挡墙在双段配水渠中的最佳位置。结果表明：配水渠进口集中主流在池内流域空间的扩散程度是出水均匀度的主要影响因素;当b在1 200~1 600 mm范围时,L取1 750~2 250 mm时的出水均匀度最优,若b大于1 600 mm,最优的L值须适当增加,但不应大于3 000 mm;当B为3 900 mm时,L最佳取值为1 750~2 250 mm,当B为5 300或6 700 mm时,最佳的L值应增加500 mm左右;采用双段配水渠时,挡墙位置应设在进口侧,而不应在配水渠的中间位置。该研究可为配水渠的设计提供一定的理论指导。     

Evaluating Projects and Assessing Sustainable Development in Imperfect Economies

We are interested in three related questions:(1) How should accounting prices be estimated?(2) How should we evaluate policy change in animperfect economy? (3) How can we check whetherintergenerational well-being will be sustainedalong a projected economic programme? We do notpresume that the economy is convex, nor do weassume that the government optimizes on behalfof its citizens. We show that the same set ofaccounting prices should be used both forpolicy evaluation and for assessing whether ornot intergenerational welfare along a giveneconomic path will be sustained. We also showthat a comprehensive measure of wealth,computed in terms of the accounting prices, canbe used as an index for problems (2) and (3)above. The remainder of the paper is concernedwith rules for estimating the accounting pricesof several specific environmental naturalresources, transacted in a few well knowneconomic institutions.     

Economic liberalization and welfare in a model with an informal sector

The paper reexamines the conventional results relating to inflow of foreign capital, removal of protectionism and structural reform programmes, in a small open economy in terms of a two-sector general equilibrium model with an informal sector. The paper shows that in the presence of labour market distortion and a protectionist policy, inflow of foreign capital may be desirable irrespective of the pattern of trade of the economy due to its favourable impact on welfare. But the welfare implications of tariff reductions and/or structural adjustment programmes, such as deregulating the formal sector labour market, depend crucially on the economy's trade pattern. The paper provides an answer to the question as to whether in a developing economy labour market reform and tariff reform should go hand-in-hand or whether one should precede the other for welfare improvement.
JEL classification: F10, F13, F21, O17.     

Structural Decomposition Analysis of Physical Flows in the Economy

Many environmental problems can be attributedto the extraction and emissions of physicalsubstances. Increasing our understanding of theeconomic and technological driving forcesbehind these physical flows can contribute tosolving the environmental problems related tothem. The input-output framework is a usefulsetting in which to integrate detailedinformation about economic structure andphysical flows. In this article a specificmethod in input-output analysis is reviewed,namely Structural Decomposition Analysis (SDA).It is based on comparative static analysis,which decomposes historical changes of a policyvariable into determinant effects. SDA has beenapplied, for example, to analyze the demand andtechnological driving forces of energy use,CO₂-emissions and various other pollutantsand resources. This article examines thetheoretical aspects of structuraldecomposition, in particular those concerningphysical flows and environmental issues.Furthermore, the article includes an extensivesurvey of empirical studies.     

论人民币内外价值偏离

近几年来,人民币同时面临对外升值和对内贬值的双向压力。本文以“一价定律”为理论视角,分析了人民币内外价值偏离的表现及其危害,并从涉外经济政策层面探讨了内外价值偏离的深层原因,进而提出纠正人民币内外价值偏离的对策性建议。     

经济增长、结构调整的累积效应与资本形成——当前经济增长态势分析

1990年以来 ,特别是 2 0世纪 90年代中后期 ,中国的经济结构发生了重大调整 :基础设施的投入奠定了城市化的基础 ,工业化在消费和出口的拉动下逐步升级。中国经济增长开始由工业化单引擎发展到工业化与城市化的双引擎。由低价工业化到高价城市化的转化以及与之相应的资金流程与资本形成方式的变化 ,一方面引起近年来中国经济的快速发展 ,另一方面也对未来中国经济的持续增长形成挑战。通过政府体制、金融体系和财税体制的进一步改革 ,完善资源配置方式 ,将是应对挑战、保持中国经济持续增长的保证。     

对我国经济增长方式转变的新思考

我国经济增长方式长期存在着由粗放型向集约型转变的困扰,表现为经济增长过度依赖于投入的增加,生产技术水平偏低,劳动者素质结构改善缓慢,经济比例关系没有理顺,产业结构不合理现象突出等。转变增长方式的关键在于增强国内自主创新能力,调整和优化产业结构,以科技进步推动经济增长由低质低效向高质高效的转化,以产业结构的调整和优化保障增长目标的实现。     

西部地区经济结构优化之我见

本文在对西部地区经济结构现状及其对经济效益的影响进行分析的基础上 ,提出了调整和优化经济结构的对策与思路 ,为有关部门和政府当局提供一些借鉴与参考