基于遗传算法的核函数参数优化

核主分量分析是一种输入输出特征非线性变换技术。选择最优或接近最优的非线性变换核函数参数,使类的可分性测度最大,是KPCA应用于特征提取的关键。本文采用高斯变异遗传算法作优化技术,实现了KPCA和GA的集成,适合核函数参数的优化选择。仿真表明,该技术可行、有效。     

Ex-post full surplus extraction,straightforwardly

Consider an estimate of the common value of an auctioned asset that is symmetric in the bidders’ types. Such an estimate can be represented solely in terms of the order statistics of those types. This representation forms the basis for a pricing rule yielding truthful bidding as an equilibrium, whether bidders’ types are affiliated or independent. We highlight the link between the estimator and full surplus extraction, providing a necessary and sufficient condition for ex-post full surplus extraction, including the possibility of independent types. The results offer sharp insights into the strengths and limits of simple auctions by identifying the source of informational rents in such environments. Harstad acknowledges hospitable accommodation by the Fuqua School of Business, Duke University, and the Olin School of Business, Washington University in St. Louis, during parts of this research. We are grateful for comments and suggestions from Richard McLean and Jeroen Swinkels.     

价格歧视下的不可再生资源的开采问题研究

自Hotelling开始,不可再生资源开采问题引起了经济学家们的注意,在此过程中,产业组织理论被应用于不可再生资源的研究.文章分析了价格歧视对不可再生资源开采的影响,结果发现,当资源的垄断开采者面向多个市场时,价格歧视因素可能使资源开采偏离最优路径.     

Uncertain Climate Change in an Intergenerational Planning Model

A three-generation planning model incorporating uncertain climate change is developed. Each generation features a production activity based on capital and an exhaustible resource. An irreversible climate change may occur in period two or three, reducing the productivity for this and the remaining generation. The model is solved by stochastic dynamic programming. If the climate impact and climate change probability is constant, the optimal period one (and two) resource extraction is larger than for the reference case of climate stability. If, however, climate impact and climate change probability increases with increased aggregate resource use, this result is reversed.     

高硫减压渣油加工方案的技术经济比较

对中国石化齐鲁分公司高硫减压渣油两种生产方案,即减压深拔工艺生产重交沥青和VRDS-FCC组合工艺生产轻质油品进行技术经济比较.结果表明:在公司裂解原料不能完全自给的前提下,VRDS-FCC组合工艺的单位利润优于减压深拔工艺,但随着重交沥青价格的上升,VRDS-FCC组合工艺的优势将逐渐减弱.     

因子分析中公因子提取方法的比较与选择

近代和现代统计分析方法中，因子分析是最重要的方法之一。因子分析中有7种提取公因子的方法，其中主成分法、极大似然法和主轴因子法是常用的方法。在着重解析这三种方法基本数学过程的基础上，对其适用条件和应用注意事项进行了比较，最后结合实例比较了不同公因子提取方法的结果，并对提取公因子过程中出现的问题给出了可能的解决办法。     

The cost of unconventional gas extraction: A hedonic analysis

We focus on identification and estimation of potentially negative environmental impacts of unconventional natural gas extraction on property values in the United States and advance previous research by contributing new data and new identification strategies for isolating these potential impacts. Our study area consists of two counties in Pennsylvania that are home to large amounts of unconventional natural gas extraction but are otherwise isolated from other resource extraction industries or large urban areas. We deploy parametric, semi-parametric, and matching hedonic regression models that include recent quasi-experimental methods and, in contrast to previous research and much popular intuition, we fail to find robust significance that negative environmental externalities of natural gas extraction are manifested in nearby property values. While there may be plausible risks associated with unconventional natural gas extraction, we do not find consistent evidence to suggest that these risks significantly affect nearby property values.     

The economic impact of shale gas extraction: A review of existing studies

Recent advances in drilling technology have allowed for the profitable extraction of natural gas from deep underground shale rock formations. Several reports sponsored by the gas industry have estimated the economic effects of the shale gas extraction on incomes, employment, and tax revenues. None of these reports has been published in an economics journal and therefore have not been subjected to the peer review process. Yet these reports may be influential to the formation of public policy. This commentary provides written reviews of several studies purporting to estimate the economic impact of gas extraction from shale beds. Due to questionable assumptions, the economic impacts estimated in these reports are very likely overstated.     

A short history of global inequality: The past two centuries

Using social tables, we make an estimate of global inequality (inequality among world citizens) in early 19th century. We then show that the level and composition of global inequality have changed over the last two centuries. The level has increased reaching a high plateau around 1950s, and the main determinants of global inequality have become differences in mean country incomes rather than inequalities within nations. The inequality extraction ratio (the percentage of total inequality that was extracted by global elites) has remained surprisingly stable, at around 70% of the maximum global Gini, during the last 100 years.     

甘肃省粮食综合生产能力不同阶段的影响因素分析

根据1978～2008年甘肃省粮食总产量、单位面积产量和人均产量等粮食生产的相关资料,对粮食生产情况进行了阶段分析;选用农膜使用量、粮食播种面积、有效灌溉面积、化肥施用量、农业机械动力、受灾面积、价格指数等指标,建立了C-D生产函数,分析了不同阶段粮食综合生产能力变动的原因.结果表明:物质投入、科技投入和政策因素是影响甘肃省粮食综合生产能力的三个主要因素.提示甘肃省粮食综合生产能力仍然偏低,但增产潜力较大.