中国城市化与生态环境耦合规律与实证分析

本文在阐明城市化与生态环境交互耦合含义的基础上,利用城市化的S型生长曲线和生态环境演变的倒U型曲线,演绎出城市化与生态环境耦合的规律曲线,并以中国的实际数据为例,进行实证分析。研究表明:(1)生态环境随城市化发展呈现出着先恶化、后改善的不规则倒U型耦合规律,但该规律曲线只是它们实际耦合的一种演变趋势;(2)1985～2005年间,中国工业废水排放量与城市化水平耦合表现出先倒U型和后U型的阶段特征,而这种特征曲线正是技术进步、产业结构高级化、人们环保意识的增强以及经济增长的压力等因素综合作用的结果。     

Experimental Economics and the Theory of Decision Making Under Risk and Uncertainty

Following a brief review of the main experimental work into the economics of risk and uncertainty, both static and dynamic, this paper reports the results of an experiment testing one of the key assumptions of the theory of dynamic economic behaviour—that people have a plan and implement it. Using a unique design which enables the plan (if one exists) to be revealed by the first move, the experiment was implemented via the Internet on a subset of the University of Tilburg's ongoing family expenditure survey panel. The advantages of using such a set of subjects for the experiment are twofold: the demographic characteristics of the set are known and therefore demographic inferences can be made; the representativeness of the set is known and therefore inferences about populations can be made. The results suggest that at least 36% of the subjects had behaviour inconsistent with the hypothesis under test: that people formulate plans and then implement them. Interestingly demographic variables are unable to explain the consistency or inconsistency of individuals. One conclusion is that subjects simply make errors. An alternative conclusion, consistent with previous experimental research, is that people are unable to predict their own future decisions. The implications for dynamic theory (particularly relating to savings and pensions decisions) are important.     

The Global Determinants of Direct Office Real Estate Returns

We investigate the determinants of direct office real estate returns by analyzing rents, capital appraisals, and total returns. A recently compiled global database of major cities in Asia, Europe, and the United States provides a unique opportunity to give a macro-view on the effects of economic growth and supply and demand factors on nominal real estate returns. The global database provides quarterly observations from 1986 to 1999. To address the smoothness problem of appraisal-based price data and regulated rents, we employ the Generalized Method of Moments to estimate a dynamic panel-data model. The model allows us to combine the cross-sectional and time-series dimension in our quarterly data. We find that gross domestic product, inflation, unemployment, vacancy rate, and the available stock all have an effect on real estate returns.     

建设工程信息集成管理系统研究

工程项目建设与管理过程中会产生大量的物化的材料——建设工程信息。静态信息资料组卷归档后将成为建设工程项目的档案资料，为工程检查验收及日后的改建、扩建、维修、管理等方面提供极其重要的依据，动态信息则为工程建设过程的管理与决策提供强力支持，而这一切都建立在对建设工程信息的有效管理基础上，从了解建设工程信息特点入手,分析客户的需求，构筑管理系统构架,开发了相应的功能模块，并付诸了实施。     

Export Sophistication: A Dynamic Panel Data Approach

In this article, we analyze export sophistication based on a large panel dataset (2001–2015; 101 countries) and using various estimation algorithms. Using Monte Carlo simulations, we evaluate the bias properties of estimators and show that GMM-type estimators outperform instrumental-variable and fixed-effects estimators. Based on our analysis we document that GDP per capita and the size of the economy exhibit significant and positive effects on export sophistication; weak institutional quality exhibits negative effect. We also show that export sophistication is path-dependent and stable even during a major economic crisis, which is especially important for emerging and developing economies.     

Modified efficient importance sampling for partially non‐Gaussian state space models

The construction of an importance density for partially non‐Gaussian state space models is crucial when simulation methods are used for likelihood evaluation, signal extraction, and forecasting. The method of efficient importance sampling is successful in this respect, but we show that it can be implemented in a computationally more efficient manner using standard Kalman filter and smoothing methods. Efficient importance sampling is generally applicable for a wide range of models, but it is typically a custom‐built procedure. For the class of partially non‐Gaussian state space models, we present a general method for efficient importance sampling. Our novel method makes the efficient importance sampling methodology more accessible because it does not require the computation of a (possibly) complicated density kernel that needs to be tracked for each time period. The new method is illustrated for a stochastic volatility model with a Student's t distribution.     

人口规模与教育资源配置良性互动机制的动态仿真

我国人口规模与教育资源配置形成了恶性循环。以社会宏观动力学为分析框架, 基于2000—2019年面板数据,采用Vensim PLE软件,构建人口规模与教育资源配置互动机制系统动力学模型。研究表明：2024年开始,人口规模下降速度将逐年加快,教育市场将出现结构性萎缩,教育资源投入总量和速度将提高;人口规模对生产水平敏感;教育资源市场配置对人口增速、权力巩固程度、权力中心化程度、物力教育资源敏感。基于研究结论,提出两者良性互动的调适策略：保持经济高质量发展,降低生育养育成本;将生育权还给家庭,全面放开生育;巩固“双减”政策成效,引导教育需求;降低权力中心化程度,利用教育市场优势;加大教育资源投入,促进优质教育资源均衡。     

湖南省农业生态与农业经济耦合性测度

[目的]考察湖南省近9年来农业生态与农业经济系统耦合发展现状,探究二者发展过程中的规律,以期找出二者协调发展模式,并为湖南省农业生态环境保护、农业经济发展提供决策依据。[方法]运用耦合协调度模型,基于熵权法为各指标进行客观确定权重,结合2007~2015年湖南省农业生态与农业经济发展的相关数据,确定农业生态与农业经济的耦合匹配分析模型,采用熵值赋权法确定各项指标的权重,构建农业生态—农业经济耦合协调评价指标体系。[结果]研究结果表明,2007~2015年湖南省农业生态与农业经济的耦合协调发展基本稳定,耦合度值均在0.9以上,二者呈协调发展趋势。其中,2014年和2015年二者的耦合度较高,分别为0.975 3和0.984 3,说明湖南省在这两年的农业生态与农业经济的协调性好,农业经济与农业生态能够相互有效促进彼此的发展。同时,仍需时刻关注生态环境的承载力,降低对自然资源的无序攫取,实现经济的可持续发展。     

粮食与经济重心迁移路径及空间耦合关系分析*——以湖北省粮食主产县为例

[目的]我国的粮食安全问题一直备受关注,作为粮食安全重要保障的粮食主产区近年来却面临着粮食生产与经济发展协调性、可持续性下降的困扰。文章以湖北省46个粮食主产县为研究区,对其粮食生产与经济发展的耦合协调状况进行研究,以期为地方政府粮食安全政策制定提供参考。[方法]以研究区粮食产量、地区生产总值、行政区划图层为数据源,构建重心模型和空间耦合模型,对粮食主产县2006—2015年间粮食重心和经济重心迁移路径、粮食生产与经济发展耦合协调状况进行分析。[结果](1)研究期间粮食主产县的粮食重心和经济重心整体上皆向西北方向转移,经济重心始终位于粮食重心东南部,经济重心的移动幅度大于粮食重心,但经济重心的移动方向更稳定。研究区北部的粮食生产地位高于南部,南部的经济地位则高于北部,粮食生产的稳定性相对低于经济发展。(2)两重心整体上虽均向西北方向转移,但具体移动方向存在较大差异,两者空间重叠性整体下降,变动一致性减弱,空间耦合性变差。(3)粮食生产与经济发展空间一致性地域分异特征明显,相较于2006年,2015年粮食经济整体协调性进一步减弱,粮食生产与经济发展日趋分散。[结论]建立重心模型和空间耦合模型对粮食生产与经济发展耦合协调状况进行研究是有效可行的,为推动粮食生产与经济发展协调稳步发展决策提供一定的参考。     

Investment planning under uncertainty and flexibility: the case of a purchasable sales contract*

Investment decisions are not only characterised by irreversibility and uncertainty but also by flexibility with regard to the timing of the investment. This paper describes how stochastic simulation can be successfully integrated into a backward recursive programming approach in the context of flexible investment planning. We apply this hybrid approach to a marketing question from primary production which can be viewed as an investment problem: should grain farmers purchase sales contracts which guarantee fixed product prices over the next 10 years? The model results support the conclusion from dynamic investment theory that it is essential to take simultaneously account of uncertainty and flexibility.