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71.
介绍了未来高速移动通信新标准IEEE802.20的总体概况,具体分析了IEEE802.20的技术特性、系统参考结构以及系统的组成模型,并对IEEE802.20标准前景分析与展望进行了详细描述。 相似文献
72.
Abstract. Economists devote considerable energies towards refining their econometric techniques to overcome difficulties connected with conducting empirical research. Despite advances in technique. it is not clear whether further refinement in this direction is worthwhile for policy purposes. It may be that no further amount of statistical adjustment of inadequate data will increase understanding, and that better data is simply necessary to add to our knowledge. But rarely is sufficient credit paid to new forms of data. In short, econometric technique is emphasized to the neglect of data innovation, as if new data were merely lying about waiting for an ingenious suggestion for use. This paper surveys advances of the last twenty five years in estimating labour supply for policy purposes with a view towards appreciating the relative contribution of both improvements in econometric technique as well as developments of new data.
After briefly detailing the key parameters which economists have sought to estimate, we describe the early 'first generation' research (circa 1970), which is plagued by problems of unobservable variables, measurement errors, truncation and selectivity bias, and non linear budget constraints. 'Second generation' research constitute attempts to resolve one or more of these difficulties, and the respective contribution of econometric technique and new data is acknowledged and assessed, including the contribution of data generated by large scale social experiments in which participants are randomly assigned to different guaranteed income plans and their labour supply behaviour measured. 相似文献
After briefly detailing the key parameters which economists have sought to estimate, we describe the early 'first generation' research (circa 1970), which is plagued by problems of unobservable variables, measurement errors, truncation and selectivity bias, and non linear budget constraints. 'Second generation' research constitute attempts to resolve one or more of these difficulties, and the respective contribution of econometric technique and new data is acknowledged and assessed, including the contribution of data generated by large scale social experiments in which participants are randomly assigned to different guaranteed income plans and their labour supply behaviour measured. 相似文献
73.
中石化上游领域竞争力和抗风险能力的定量分析 总被引:2,自引:0,他引:2
安丰全 《石油化工技术经济》2001,17(3):16-21
在分析石油公司上游领域竞争力影响因素的基础上,提出了定量评价上游 领域竞争力和抗油价风险能力的定量评价方法,按上游综合竞争力指标将世界石油公司分为三类,第一类公司的指标值均在90以上,第二类公司在55-70,第三类公司在25-35。分析表明中石化集团上游领域竞争力较低,承受体油价的时间很短,但是,中石化集团公司上游竞争力和抗风险能力有很大的改善余地,并提出提高竞争力和抗风险能力的措施和建议。 相似文献
74.
Guojie Zhao" Tianjin Zhiyong Shi Guojie Zhao 《美中经济评论(英文版)》2006,5(2):9-12
The selective principle of mutually exclusive project is the maximum of net present value, It is difficult to make decision when NPVA is equal to NPVLB. Some assistant analyses are put forward in "Enterprise Investment Decision Management". The scientific marginal analysis shows that the assistant analyses including the duration analysis are wrong. This problem can be solved by the classical marginal analysis. 相似文献
75.
76.
Underdetermination, associated with the DuhemQuine thesis,is a familiar if under-researched theme in economics. In thelight of this, we examine the development of urban land andhousing economics. Through its Cartesian dualistic delineationof theory and data, the contemporary mainstream approach appearsunable to circumvent the problem of underdetermination. In effect,it employs the strong version of DuhemQuine in its retentionof the assumption of a single, unitary competitive market (andassociated accessspace trade-off). Conversely, we highlightthe affinity of Ely's (and the later Columbia School's) approachto pragmatists Dewey and Peirce, which provides a more fruitfulbasis for explanation. 相似文献
77.
浅析石油化工项目产品市场分析 总被引:2,自引:0,他引:2
谭国林 《石油化工技术经济》2002,18(5):39-43,60
市场分析是项目前期的重要工作之一,目前尚未赢得人们足够的重视。国外的投资咨询公司对石油化工项目的产品市场分析有其一套比较完整的操作程序和评估体系,以BOPP为案例介绍了市场分析的思路和方法,并且指出市场分析作为一种新的理念,必须进一步深化和细化,逐步加以完善。 相似文献
78.
以油藏监测工作中的油藏压力监测为例,介绍了标准化工作在压力资料录取及解释分析中的作用。并用实例说明了标准化作业在油田开发方案的制定及油藏压力监测中的应用。 相似文献
79.
80.
Predicting the geo-temporal variations of crime and disorder 总被引:2,自引:0,他引:2
Traditional police boundaries—precincts, patrol districts, etc.—often fail to reflect the true distribution of criminal activity and thus do little to assist in the optimal allocation of police resources. This paper introduces methods for crime incident forecasting by focusing upon geographical areas of concern that transcend traditional policing boundaries. The computerised procedure utilises a geographical crime incidence-scanning algorithm to identify clusters with relatively high levels of crime (hot spots). These clusters provide sufficient data for training artificial neural networks (ANNs) capable of modelling trends within them. The approach to ANN specification and estimation is enhanced by application of a novel and noteworthy approach, the Gamma test (GT). 相似文献