单螺杆泵的合理选择研究

为合理选择单螺杆泵,将螺杆泵抽油井作为一个大的生产系统,把油层、套管、油管、井下螺杆泵机组和井口作为5个子系统,利用系统节点分析法,确定出泵的工作载荷,并根据油井的实际工作参数,对泵特性曲线进行换算。由油井工作参数和单螺杆泵输油特性曲线对比可知,单螺杆泵的特性曲线和油井工作参数配合最好的情况是:油井的工作点应位于泵特性曲线Q0-H0的下面,而且在高效区的开始处。实践证明,采用这种方法选泵,既能保证油井的产量,又能明显地提高单螺杆泵整套装置的效率,还能延长泵的使用寿命。     

中国农产品加工产业组织创新与政策选择

通过对农产品加工业发展状况调查研究和个案分析,概括了农产品加工业的产业组织特征和绩效评价,剖析农产品加工业发展中存在的囚徒困境、过度竞争、逆向选择等问题及其成因,并提出了相应的政策建议。     

绿色政府评价方法的比较与改进

改革开放30多年来,我国在各项事业取得了举世瞩目的成就的同时,更面临严峻的环境问题。生态环境不断恶化,资源面临枯竭,严重威胁到我国经济的长远可持续发展。推行绿色政府成为大势所趋,并且尤为紧迫。与此相应的绿色政府评价方法的选择成为当务之急。系统总结并比较当前国内外评价方法,并针对绿色政府建设提出评价方法的选择与改进意见。     

新疆新型工业化背景下外向型主导产业选择研究

新时期供给与需求的双重约束,使得新疆进入了新型工业化时期。同时随着我国对外开放程度的不断深化,新疆在中国实施向西开放战略中的地位也日益凸显出来。为了寻找外向型经济新的增长空间,促进产业结构调整与升级,加快区域新型工业化进程,必须要构筑外向型主导产业。构建了增长潜力、关联效应、对外开放度、技术进步、就业功能、可持续发展、区域比较优势七个外向型主导产业选择基准和13个量化指标。以此为基础,实证选择分析得到了新疆新型工业化背景下外向型主导产业。它们是电气机械及器材制造业,食品制造业,石油加工炼焦加工业,化学纤维制造业,纺织服装、鞋、帽制造业,化学原料及化学制品业,非金属矿物制品业七大产业。     

居民住房区位选择问题研究

以行为区位理论为理论基础,摒弃在选择住房过程中对房屋价格的研究,仅从居民个人行为特征出发,分析购房者对区位和居住空间的偏好,以及二者之间的关系.同时对影响消费者居住区位选择的社会结构和因素与个人住房选择行为之间的相互作用进行深入的研究,并解释了消费者是如何在最优区位与次优区位之间进行抉择的.     

The Bioeconomics of Cooperation

When transactions and information are costly and exchange is non-simultaneous, ‘institutions matter’. They matter because exchange under these circumstances subjects the participants to potentially harmful behaviors by other participants, among which are: opportunistic behavior, agency, the free-rider problem, cheating, moral hazard, and adverse selection. Institutions constrain these behaviors, allowing the participants to take advantage of the gains from trade and specialization, and thereby facilitating cooperation. Individuals adhere to institutional rules because they gain by doing so. Because the individual gains are inseparable from the structure of the institutions, the institutions themselves necessarily become the focus of the analysis—as we see in the new institutional economics (NIE). The new group selection position in biology involves a similar shift in focus from the level of the individual to the group when studying the evolution of altruism. But some of the proponents of group selection go further, arguing that altruism in biology evolves because it is in the interest of the group, but not the individual. In fact, group level analysis is necessary in biology, as in the NIE, because it allows for the discovery of ‘institutions’ that constrain cheating, opportunistic behavior, etc., thereby making participation in the group in the long-run self-interest of the individual. This revised version was published online in August 2006 with corrections to the Cover Date.     

论农业保险经营模式的选择--基于防范信息不对称之上的研究

信息不对称问题是阻碍农业保险经营与发展的重要障碍,在纯商业化形式不适用的情况下,单纯的政策性农业保险也难以化解此矛盾."互助合作 联合共保"农险经营模式可以充分发挥农业保险作为一项不可替代的经济补偿制度的作用.     

基于生态文明理念下化解城乡生态环境二元化的路径选择

改革开放30多年以来,我国城乡经济发生了翻天覆地的变化,城乡居民经济水平和生活质量都得到了普遍提升。但随着城市化、工业化进程加快,城乡经济也随之拉开差距,在城乡经济结构二元化的影响下,城乡生态环境也出现了严重的二元化趋势。介于此,本文以"天人合一、人地和谐"的生态文明理念为指导思想,在挖掘生态文明与生态环境保护两者内在关系的基础上,结合实际以分析我国城乡生态环境严重二元化的现况为出发点,剖析导致城市与乡村生态环境二元化的三大矛盾,并提出六大破解城乡生态环境二元结构可行之路,为共同构建美好生态环境提供良策。     

Estimating gravity equation models in the presence of sample selection and heteroscedasticity

Gravity models are widely used to explain patterns of trade. However, two stylized features of trade data, sample selection and heteroscedasticity challenge the estimation of gravity models. We propose a two-step method of moments (TS-MM) estimator that deals with both issues. The Monte-Carlo experiments show that the TS-MM estimates are resistant to various combinations of sample selection and heteroscedasticity. Moreover, the TS-MM estimator performs reasonably well even when the data generating process deviates from the TS-MM assumptions. We revisit the world trade in 1990 to illustrate the usefulness of the proposed model, with emphasis on the identification of the extensive margin of trade.     

Assessing the Impact of the ‘Decoupling’ Reform of the Common Agricultural Policy on Irish Farmers’ Off‐farm Labour Market Participation Decisions

This paper assesses the impact of the ‘decoupling’ reform of the Common Agricultural Policy on the labour allocation decisions of Irish farmers. The agricultural household decision‐making model provides the conceptual and theoretical framework to examine the interaction between government subsidies and farmers’ time allocation decisions. The relationship postulated is that ‘decoupling’ of agricultural support from production would probably result in a decline in the return to farm labour but it would also lead to an increase in household wealth. The effect of these factors on how farmers allocate their time is tested empirically using labour participation and labour supply models. The models developed are sufficiently general for application elsewhere. The main findings for the Irish situation are that the decoupling of direct payments is likely to increase the probability of farmers participating in the off‐farm employment market and that the amount of time allocated to off‐farm work will increase.