SEM图像分形维数的影响因素研究

以玻璃光纤、碳纤维纸和两种机加工表面样本的扫描电子显微镜图像为对象,运用盒维法研究了不同的放大倍数和采集过程中受到的噪声干扰对分形维数的影响.研究结果表明,随着放大倍数增大或随着椒盐噪声密度和高斯随机噪声方差的减小,分形维数下降.放大倍数和噪声对分形维数都有较大影响.在扫描电子显微镜图像分形维数的计算中,可以依据试样的结构特征选择合适的放大倍数,进行去噪处理后再计算图像的分形维数.     

建筑工程管理中全过程造价控制对策研究

随着社会经济和科学技术的发展,建筑工程如雨后春笋般涌现出来,规模也呈现出不断扩大的趋势.在对建筑工程进行管理的过程当中,工程造价是一个十分重要的因素,但是,要想在建筑工程当中对工程的造价进行良好的控制是十分不容易的,并且工程造价贯穿于施工的全过程.因此,要对工程造价进行全面良好的控制.     

Altruism and the Economic Values of Environmental and Social Policies

Altruism is a type of non-use value which can have different definitions depending on the type of goods entering the utility function of the altruists and their expectations about the contributions of others. The purpose of this paper is to measure the trade-offs between different types of altruist values originating from social and environmental policies. Environmental policies are concerned with reducing health effects from a power plant while social policies involve both the attainment of public facilities for education and leisure and an increase in the income of the affected population. The empirical application utilizes a choice experiment technique which allows for valuation of multiple goods. Health effects are decomposed into the values of the risk of becoming ill, the duration of the episodes and the limitations imposed by illness. Altruist values are elicited from a population that is not affected by pollution. Results show that altruism is significant for policies directed to reducing health effects and improving the income level of the affected population, whereas there is egoism for a policy aimed at improving public facilities in the polluted suburb. The value of altruism is significantly influenced by the expectations of net benefits to be received by the affected population.     

安徽省区域性税收弹性的实证分析——及税收与经济增长的关系分析

文章通过对安徽省税收收入与GDP数据的回归分析来研究区域性的税收与经济增长之间的关系,并通过对安徽省区域性的税收弹性分析,来全面分析安徽区域性的税收增长与经济增长的关系,最后根据相关分析得出结论并提出保持税收与经济增长健康发展的建议。     

徐州市生态经济系统的能值分析

本文应用能值理论．对徐州地区生态经济系统进行了分析．主要涉及能值投入率、能值使用强度（能值密度）、人均能值使用量、人口承载力、电力能值使用量比、能值一货币比、环境负荷率、净能值产出率、可持续发展指数等9个指标及其发展趋势，并与其他国家和地区的有关指标进行了比较研究。结论表明，徐州市是资源输出型的生态经济区域，经济发展仍处于欠发达阶段．还有较大的经济发展潜力。     

城乡关系协调视角下的中国乡村工业化

实现乡村新型工业化是中国城乡区域实现良性互动及促进城乡和谐发展格局的关键途径与基本动力。在城乡关系协调的过程中推进乡村工业化，必须重视乡镇企业在新时期的转型与发展，创新农业产业化经营与运作模式，不断培育壮大农业企业家的人力资本支撑，最终实现城乡协调互动基础上的共同繁荣与进步。     

自然保护地自然资源资产产权制度现状辨析

“建立以国家公园为主体的自然保护地体系”是党的十九大所提出的国家公园体制建设的新方向。实现自然保护地的有效保护管理是其重要内容，关键在于通过改革形成科学、合理的自然资源资产产权制度，而厘清自然资源资产产权制度的现状则是进行改革的前提。首先，对现行法律进行系统梳理，明确法律所认定的自然保护地中的自然资源类型。其次，从自然资源的产权种类及所有权改变、用益物权流转三方面总结了自然保护地自然资源资产的产权制度现状。再者，从各类自然保护地申报设立的条件和环保督查中反映出来的问题两方面入手分析了自然保护地的自然资源保护管理现状，从国家公园体制试点采取的措施出发分析了目前的改革探索，并提炼出自然保护地自然资源资产产权制度存在的四大问题，即自然资源资产产权的界定和要求较局限、自然资源所有权行使人虚位、公权与私权的利益协调机制不健全、改革探索中物权途径面临制度障碍。最后，从自然资源资产产权制度设计的角度提出了改革的4个方向。     

Existence of a competitive equilibrium in a one sector growth model with heterogeneous agents and irreversible investment

Summary. We prove existence of a competitive equilibrium in a version of a Ramsey (one sector) model in which agents are heterogeneous and gross investment is constrained to be non negative. We do so by converting the infinite-dimensional fixed point problem stated in terms of prices and commodities into a finite-dimensional Negishi problem involving individual weights in a social value function. This method allows us to obtain detailed results concerning the properties of competitive equilibria. Because of the simplicity of the techniques utilized our approach is amenable to be adapted by practitioners in analogous problems often studied in macroeconomics. Received: September 13, 2001; revised version: December 9, 2002 RID="*" ID="*" We are grateful to Tapan Mitra for pointing out errors as well as making very valuable suggestions. Thanks are due to Raouf Boucekkine and Jorge Duran for additional helpful discussions. We also thank an anonymous referee for his/her helpful comments. The second author acknowledges the financial support of the Belgian Ministry of Scientific Research (Grant ARC 99/04-235 “Growth and incentive design”) and of the Belgian Federal Goverment (Grant PAI P5/10, “Equilibrium theory and optimization for public policy and industry regulation”). Correspondence to: C. Le Van     

企业在同质产品市场的差异化战略行为——一个对我国反垄断立法的产业组织理论解释

我国在加入WTO后,一些重要的服务领域面临着全面对外开放。由于转换成本的存在,使得该领域中本来在购买前功能相近的同质商品或服务,在购买后成为异质的商品。企业因而拥有相对于消费者的事后垄断的权力。为此,企业有动机在初期采取战略行为吸引消费者。这既缓和了后续阶段的企业间竞争,也在整体上将该行业的产品价格维持较高水平。它可能会降低社会效率和消费者福利。文章通过分析企业间在同质商品市场竞争的市场效果和福利后果,为在我国该领域反垄断立法提供了理论解释。     

Price–Cost Margins and Structural Change: Sub-Contracting within the Salmon Marketing Chain

Some recent studies have benefited from advances in time series econometrics in order to evaluate price transmission mechanisms along the marketing chain. Due to the length of time series, structural changes may affect the evaluation of price–cost margins. In the case of the fresh salmon trade between Norway and France, the gross margin between producers and retailers has changed in level between January 1988 and December 1999. This article accurately identifies the date of a structural change using a range of recent ADF testing procedures (Gregory–Hansen tests, forward and backward recursive tests), before looking for the causes of the change through a survey. Two major factors can be identified: the product form and the marketing channel. Interestingly, both the increasing level of processing and the development of supermarket chains have resulted in a new role for the intermediaries, shifting from mere commercial intermediation to sub‐contracting for the big retailers.