精馏过程的节能和优化设计的探讨

精馏过程的节能,对于减少能源消耗,降低生产成本和保护环境具有十分重要的意义.在精馏过程中可以采用最适宜回流比操作和最佳进料状态,使用中间冷凝器和中间再沸器,高效精馏、热泵精馏.合理安排多组分物料分离流程,直接利用过程热量及开发应用高效换热器等措施.本文从最佳回流比R的选择、进料温度及进料状态的确定等方面,详细的分析了在精馏塔的设计过程中,如何实现设计的优化问题,以实现节能降耗.     

The effects of transition on the distribution of income in China

Using two large samples for 1988 and 1995 we decompose the Gini coefficient of household income according to type of income with the purpose of analyzing reasons for the rapid increase of inequality. The results show that the change in relative size of money income and its changed profile are found to be the major processes behind the rapid increase of income inequality in rural China. Changes in housing allocation and an increased number of retirees in combination with higher benefits have made inequality increase in urban China and in China as a whole. JEL classification: D31, P27.     

FACTORS THAT AFFECT THE LONG‐TERM SURVIVAL OF MICRO,SMALL AND MEDIUM ENTERPRISES IN ETHIOPIA

There is an increasing recognition of the potential importance of micro, small and medium enterprises (MSMEs) for employment, income and poverty reduction in Ethiopia. Although the MSME sector contributes significantly to the national economy, the high failure rate among well established small businesses and enterprises is a matter of major concern. A random sample of 500 small businesses and enterprises selected from five major cities in Ethiopia were followed up for 6 years in order to assess the impact of influential factors that affect the long‐term survival and viability of small enterprises. Hazard ratios estimated from the Cox Proportional Hazards Model were used to quantify the impact of key predictors of survival. Businesses that ceased operation were characterised by inadequate finance (61%), low level of education (55%), poor managerial skills (54%), shortage of technical skills (49%), and inability to convert part of their profit to investment (46%). The study shows that participation in social capital and networking (iqqub schemes) was critically helpful for long‐term survival. Businesses that did not participate in iqqub schemes regularly were found to be 3.25 times more likely to fail in comparison with businesses that did. Results of the study have implications that could be used for developing policy initiatives that are aimed at fostering long‐term growth in small businesses and enterprises.     

上市公司利润操纵的经济动机

政府的每一次政策出台都为企业带来了新的生机与动力,但同时也诱导着一些企业进行着利润操 纵,我们应该看到,中国股票市场走过的10年道路中,规范与反规范的争斗从来没有停止过,正是由于 这样,促使我国证券市场不断发展。     

养老保险金替代率研究

养老保险金替代率是指一定地区当年离退休(含退职，下同)人员的养老金平均水平与该地区当年职工平均工资水平的比率，其是否合理，将影响到养老保险制度安排和政策取向。养老保险金替代率目标的确定，将受到一个国家或者地区的社会保障水平和经济发展水平等因素的影响。按照中国对基本养老保险制度改革的总体思路，未来基本养老保险金替代率目标确定为60％左右。目前，中国基本养老保险金替代率目标已经接近制度改革的目标，北京市的基本养老保险金替代率明显低于全国水平。企业退休金的替代率又明显低于事业和机关单位的退休金替代率，并呈现持续下降的趋势，应当设法进行遏止。     

刍议我国增值税转型

实行消费型增值税有利于加快企业发展,提升产品竞争力。目前我国已具备增值税转型条件,宜采用“一步到位”方式,但不宜提高税率。     

Demand‐side housing policy in Costa Rica: a response to the housing deficit

The purpose of this study was to establish what the housing needs of Costa Rica are and to assess what policies have been implemented to respond to their housing deficit. In order to answer these questions, a combined methodology consisting of primary and secondary data was used. Using open‐ended questions and a topic schedule, face‐to‐face interviews with Costa Rican housing authorities were conducted at the interviewee's work place in Costa Rica in May 2003. The most recent secondary data available in the country was used to compute the housing deficit and to study the effects of demographics on current housing needs. Sources of the secondary data were the Costa Rica Ministry of Housing and Human Settlements, and the National Institute of Statistics and Census. The Costa Rican government has made great progress in reforming the housing finance system in order to meet the housing demand of its citizens. In 2002, Costa Rica had a 75.6% home ownership rate. Yet, even in light of the housing system's current success, many social, economic and political barriers threaten to undermine its accomplishments and the peoples’ ability to obtain safe and affordable housing. The paper considers the strengths and weaknesses of the current housing finance system as well as the government strategies for addressing difficulties.     

中国城市住宅市场的结构差异性分析

市场价商品房、经济适用住房和廉租房构成了目前中国城市住宅市场的供应体系.依据中国30个主要城市的房地产开发统计数据,选择吸纳率作为评价住宅市场供需均衡状态的指标,利用固定影响变截距模型,重点研究了商品房和经济适用住房供给结构的城市差异性.研究发现,在城市住宅市场中,经济适用住房市场和商品房市场具有很强的相关性.作为具有政府资助性质的经济适用住房建设,存在典型的地域性特征,其政策的设定和实施会对整个住宅市场产生影响,地方政府应在利用比较全面的住宅市场指标体系进行综合分析基础上,制定适合本地的经济适用住房政策.     

价值型投资在中国证券市场上的有力证据

本文给出了1994年至2005年间价值型投资在中国A股市场中的有力证据。Fama—MacBeth回归表明在中国A股市场中存在着显著的市盈率和市净率溢价，1994年至2005年中牛市和熊市的滚动策略显示了我国A股市场中的价值效应，并且风险和收益之间基本上呈现出收益大、风险大的特征。本文的实证研究结果将有助于中小投资者以及机构投资者的长期投资决策。