B2C电子商务物流配送中心选址模型研究

分析了B2C电子商务的发展趋势、发展瓶颈即物流配送成本,为优化物流成本,构建了基于不同路段运输单价不同的最优运输费用的物流配送中心选址模型.     

从外部性控制策略分析主要环境经济手段的异同

随着世界经济的发展,环境污染问题日益严峻。环境污染是最典型的负外部行为。本文分析了西方经济理论中关于控制环境方面负外部性两种策略的分歧,对比了以这两种策略为理论渊源的排污收费制度和排污权交易制度的异同及各自的适用条件。     

论在中国B2C发展的若干问题

我国电子商务的环境在不断改善,接受网上购物方式的消费者越来越多.但2001年中国B2C并没有表现出太多令人欣喜之处,甚至部分曾经领先的电子商务网站不得不面对生死存亡的抉择.造成这种现状的原因不仅仅是电子商务整体的一些原因,也包括一些影响B2C发展的特有原因.如市场发育问题、互联网的环境和条件问题、信用制度完善的问题、物流配送问题、立法问题、具体经营问题等.这些瓶颈若不能得到合理的解决,对于电子商务发展的影响将会是巨大的.     

Efficient markets and Bayes’ rule

Summary. A series of financial anomalies motivated the development of new theories that modify the rational expectations ideal. Two possibilities have been systematically explored. The literature on behavioral finance relaxes the assumption that agents form beliefs according to the laws of probability and assume, instead, that simpler heuristic rules are used. Another stream of the literature assumes that agents process information according to Bayes rule, but do not posses sufficient information to know the true data generating process. In this paper, Bayesian and Behavioral agents coexist and trade in a standard dynamic asset pricing model. A long-standing conjecture is demonstrated. It is shown that, under suitable assumptions, Bayesian agents drive Behavioral, non-Bayesian agents out of the market. Hence, asset prices are eventually determined under the Bayesian paradigm.Received: 3 June 2004, Revised: 17 September 2004, JEL Classification Numbers: D83.Preliminary versions have circulated under the titles Markets Favor Bayesian Models and Market Selection of Empirical Models under Limited Information. I thank Larry Blume, David Easley, Larry Epstein, Armando Gomes, Bruce Hansen, Lars Hansen, Richard Kihlstrom, Grace Koo, George Mailath, Werner Ploberger, Andrew Postlewaite and Shakeeb Khan for useful comments. I also thank participants at the NBER GE meetings, Evolutionary Finance conference in Zurich, Latin American Meetings of the Econometric Society, Stanford Institute for Theoretical Economics, the Instituto de Matematica Pura e Aplicada, the theory seminar at Brown, Chicago, Harvard-MIT, Minnesota, Penn and Wisconsin. I gratefully acknowledge the financial support from the National Science Foundation Grant SES 0109650.     

Enforcing Emissions Trading when Emissions Permits are Bankable

We propose enforcement strategies for emissions trading programs with bankable emissions permits that guarantee complete compliance with minimal enforcement costs. Our strategies emphasize imperfect monitoring supported by a high unit penalty for reporting violations, and tying this penalty directly to equilibrium permit prices. This approach is quite different from several existing enforcement strategies that emphasize high unit penalties for emissions in excess of permit holdings. Our analysis suggests that a high penalty for excess emissions cannot be used to conserve monitoring effort, and that it may actually increase the amount of monitoring necessary to maintain compliance.The authors are grateful to Anthony Heyes and three anonymous referees for their valuable comments. Partial support for this research was provided by the Cooperative State Research Extension, Education Service, U. S. Department of Agriculture, Massachusetts Agricultural Experiment Station under Project No. MAS00871.     

黄龙洞旅游开发对洞内生态环境和人的影响研究

通过对黄龙洞年内不同季节定点测定，同时与对旅游影响还不大的龙王洞对比测定，作者发现黄龙滑滑内空气CO2浓度的明显变化主要受客流量的影响。旅游旺季和黄金周客流量急剧增长带来的洞内空气CO2浓度大幅度增长，有利于岩溶作用，但洞内黑暗、高湿、低温的生态环境，对洞内工作人员身体健康有害。洞穴内岩溶景观的变化，主要受漫长的自然岩溶过程的影响，与洞内开发旅游活动的关系不大，但与洞顶山地植被保护状况有密切关系。     

Endogenous lifetime and economic growth

Endogenous mortality is introduced in a two-period overlapping generations model: probability of surviving from the first period to the next depends upon health capital that is augmented through public investment. High mortality societies do not grow fast since shorter lifespans discourage savings; development traps are possible. Productivity differences across nations result in persistent differences in capital-output ratios and relatively larger gaps in income and mortality. High mortality also reduces returns on education, where risks are undiversifiable. When human capital drives economic growth, countries differing in health capital do not converge to similar living standards, ‘threshold effects’ may also result.     

Norwegian Emissions of CO2 1987–1994 A Study of Some Effects of the CO2 Tax

Several countries have introduced taxes on fossil fuels with the aim of reducing atmospheric emissions, partly because of local environmental goals (SO₂, NO_x) and partly to participate in a global effort to reduce emissions of greenhouse gases. Many macroeconomic studies, based on both global and national models, have been made of how emissions can be reduced with the help of taxes and the consequent reduction in GDP following the introduction of such taxes. Norway has had a CO₂ tax for five years, thereby providing a unique opportunity to evaluate the effects of this tax on emissions. The paper provides a counterfactual analysis of energy consumption and emissions if no CO₂ taxes had been introduced, compared with the actual situation in which such taxes exist. The effect of a CO₂ tax on oil consumption, and thus CO₂ emissions is studied on the basis of partial economic models for various sectors of the Norwegian economy. The study indicates that the CO₂ tax has had an impact on CO₂ emissions in Norway.     

Impacts of an EC carbon/energy tax and deregulating thermal power supply on CO2, SO2 and NOx emissions

Emission of CO₂, SO₂ and NO_x are all closely linked to the burning of fossil fuels. Here we report on simulations done by linking a Sectoral European Energy Model (SEEM), covering energy demand in nine Western European countries, with the emission-transport-deposition model RAINS developed by IIASA. The study analyses emissions of CO₂, SO₂ and NO_x, deposition of sulphur and nitrogen and the extent of areas where the critical load for sulphur is exceeded in year 2000 under four different energy scenarios. Two different sets of future behavioural patterns for the thermal electric power production sector are considered. In one regime, called the plan-efficient regime, the sector is assumed to follow official plans with regard to investment in new capacity. In the other regime, called the cost-efficient regime, the thermal power sector is assumed to behave in a cost minimizing manner. The effects of the proposed EC carbon/energy tax are studied under both regimes, giving rise to altogether four scenarios.In both regimes the effect of the EC tax is to reduce emissions by between 6 and 10 per cent in year 2000 relative to the scenarios without the tax. A change of regime, from the regulated, plan-efficient regime to the market-based, cost-efficient regime, will, by itself, reduce emissions of CO₂ and NO_x by approximately 3 per cent, while SO₂ emissions are reduced by 13 per cent. The EC tax will reduce sulphur deposition by more than 5 per cent in the nine model countries under the plan-efficient regime. A change of regime further reduces the total deposition by 9 per cent. The area where depositions exceed the critical load is reduced by approximately 6 per cent in year 2000 by the tax in both regimes. Changing from the plan-efficient to the cost-efficient regime has a similar impact.Although the emission reductions due to the EC tax may seem modest, they are shown to have a sizeable effect on the technological abatement costs of reaching targets like those prescribed in the Sofia protocol on the stabilisation of NO_x emissions, and the Helsinki protocol on SO₂ emission reductions. This is part of what can be considered to be secondary benefits of the EC carbon/energy tax.     

应用电法新装置勘探二维与三维地电体

本文通过对新装置条件下位场特征的分析,应用边界单元法及解析法的计算结果,发现当二维或三维电性不均匀体与测量电极位于背景场同一等位面时,视电阻率异常反映最明显。从而提出了圆弧交会法确定二维或三维地电体中心理深的方法,并给出了若干计算实例。结果表明,此方法简便有效且精度较高。