人民币新汇制改革的贸易效应之谜——基于我国对外经济贸易特征视角的协整研究和脉冲分解

关于人民币汇制改革在我国贸易均衡方面的表现,文章运用Johansen模型揭示出:人民币升值是近两年贸易顺差形成的主要推动因素,马歇尔-勒纳条件在我国并不适用;依托于我国现行的经济贸易特征,未来一段时间我国仍将唱响贸易顺差的主旋律;在人民币加速升值的今天注重升值节奏对于保持我国贸易收支的稳定不容忽视,这一观点通过脉冲响应函数与方差分解得到了有效印证.     

Induced innovation and land degradation: Results from a bioeconomic model of a village in West Africa

This paper introduces a modeling method which simulates a village's response to population and market pressure. The method combines a recursive and dynamic linear programming model with a biophysical model of soil condition and plant growth that predicts yields and land degradation for different type of land, land use and cropping patterns. The linear programming model simulates farmers' plans aggregated at the village level under constraints of risk aversion, food consumption, land area, soil fertility, soil depth, labor and cash availability. Detailed agroecological factors determine Ihe main processes of land degradation. A large number of technological alternatives, representing different degrees of labor and/or land-saving techniques available in the study areas, are introduced, taking into account their respective constraints, costs and advantages. The method has been calibrated for a village located in the sub-humid region of Burkina Faso. Several simulations are carried out to the Year 2030. The results show that population pressure leads to intensification and investment in land conservation practices out not necessarily to better farm incomes. Increasing market opportunities can play a more positive role in boosting productivity, but for the next decades the best way to increase production per farmer is to let farmers migrate from the high-population-density areas to the low-population-density areas because, under the current economic conditions of most Sahelian countries, intensification per hectare is stil more expensive than the fallow system.     

拓扑概念与极限

本文通过泛函分析中的实例,建立拓扑的概念,能比较直观地加深对拓扑的实质及极限的理解。     

我国进出口贸易关系的时间检验

本文运用E-G两步法,分析我国自1951年至2003年期间对外贸易出口总额和进口总额之间的关系。实证分析表明:进口总额和出口总额之间存在长期稳定的均衡关系,通过格兰杰检验发现,进口总额和出口总额之间还存在双向的格兰杰因果关系。本文在协整分析的基础上建立误差修正模型,分别从长期和短期对两者之间的关系进行定量分析。     

影子银行对我国金融稳定性影响的实证分析

近年来我国影子银行发展迅速,影子银行对金融稳定性的影响引发关注。基于2001—2012年年度数据,选取委托存款和信托存款、委托贷款和信托贷款、未贴现银行承兑汇票、集合理财产品、社会融资规模等作为影子银行的代理指标,采用协整检验和误差修正模型（ECM）实证分析影子银行发展和金融稳定性之间的短期波动和长期均衡关系。结果表明,影子银行作为我国传统金融体系的有效补充,其过快的规模扩张明显降低了金融体系钧稳定性。目前,我国金融环境还很不成熟,影子银行发展应遵循循序渐进的原则,而不能脱离必要的监管。     

The economic impacts of drought on the economy of Iran: An integration of linear programming and macroeconometric modelling approaches

In this paper, we provide economy-wide estimates of the costs of drought in the cropping sector of the Iranian economy, using a linear programming model to estimate the direct costs on agriculture, and a macroeconometric model to trace the indirect impacts on the rest of the economy. The results indicate that a severe drought such as the one that occurred in the crop year 1999-2000 imposes a direct cost of 1605 million USD, equivalent to 30.3% of the total value added of the cropping sector in Iran. This, in turn, leads to a 12.7% reduction in the value added of other agricultural sub-sectors (livestock, fisheries and forestry). In the rest of the economy, the manufacturing and service sectors experience value added declines of 7.8 and 3.7%, respectively. In addition, there is a substantial decrease in investment in the agricultural, manufacturing and service sectors. Thus, such a drought reduces overall GDP by about 4.4%, and it would also result in decreased non-oil exports, increased food imports, and a rise in inflation. The results of some drought mitigation simulations are reported in brief. Such estimates strengthen the case for increased attention to drought strategies and management in agriculture in Iran and elsewhere.     

民间投资与产业转型——以浙江省为例

本文以浙江省为例,利用浙江改革开放后30多年的数据资料,对民间投资比重和三次产业的比重进行协整建模分析,分析结果表明,民间投资对浙江三次产业结构的变化起到重要的作用。民间投资比重上升是拉动浙江第三产业比重上升的原因,从而也说明了浙江第三产业的发展主要是依靠民间资本的投入;但对第二产业而言,民间投资对其的作用是反向的,这说明浙江第二产业的发展主要不是依靠民间资本的投入,而是依靠政府的投资。     

Estimating the long-term effects of advertising on sales: a co-integration perspective

Co-integration econometrics have important theoretical advantages over more traditional approaches to estimating the long-term effects of one variable on another. When advertising and sales data are co-integrated, adaptations of common econometric procedures may be used to estimate the long-term effects directly rather than inferring them from short-term relationships. This paper presents a method for detecting and estimating co-integrating relationships using ordinary least-squares regression procedures. The method is illustrated with the well-known Lydia Pinkham data from 1907 through to 1961. The results show that there was a strong positive relationship between Lydia Pinkham advertising and sales in the long-term. Implications of the method and findings are discussed.     

The impact of e-commerce: It always benefits consumers, but may reduce social welfare

This paper investigates the impact of e-commerce on social welfare using a linear city model. Our model incorporates the diversity of consumers such that some can purchase the good via the Internet while others cannot. Our main result is as follows. The appearance of e-commerce enhances retail competition and always increases consumer surplus. However, total surplus does not necessarily improve. This is because the equilibrium market division between conventional stores and e-commerce is not socially optimal and efficiency loss of distribution accrues if the population of Internet shoppers is small and/or the cost of e-commerce is high. Our theoretical results indicate that the small e-commerce market share in the Japanese and US economies may result in welfare loss.     

线性集成稳压器的安全应用

集成稳压器应用非常广泛，而在使用中却存在安全保护的问题，本文介绍了一些主要的保护方法，并作了简要的分析