Diversification strategy with random yield suppliers for a mean–variance risk-sensitive manufacturer

We consider the diversification strategy for a mean–variance risk-sensitive manufacturer with unreliable suppliers. We first analyze the linear model and find that the suppliers are selected according to the descending order of their contributed marginal expected profit, and increasing the manufacturer’s risk-averseness leads to a more even allocation of demand across the suppliers. Then, we study the general newsvendor model. By approximating the leftover inventory with a normal distribution, we establish the general properties of the active supplier set and show that the supplier selection rule is similar to that under the risk-neutral setting when the demand uncertainty is large. Moreover, we conjecture that the selection rule also applies when the demand uncertainty is low, which we verify with an extensive numerical study. Our paper makes two contributions: First, we establish the properties of the optimal diversification strategy and develop corresponding insights into the trade off between cost and reliability under the mean–variance framework. Second, we perform comparative statics on the optimal solution, with a particular emphasis on investigating how changes in the supplier’s cost or reliability affect the risk-averse manufacturer’s ordering decisions and customer service level.     

生态资本的界定及衡量:文献综述

通过对国内外生态资本相关理论成果的梳理和归纳,评述了生态资本的概念界定、核算衡量和运营机制三方面的内容,着重介绍了森林生态资本相关研究进展,并指出了其未来发展趋势:一方面结合中国林权制度改革的实际、森林生态效益补偿的推进,想方设法解决所面临的现实问题,完善森林生态资本理论;另一方面借鉴国内外其他较成熟生态资本类型研究成果,不断丰富森林生态资本的分析视角,为其合理界定、科学核算、高效运营奠定基础。     

Fractional integration in daily stock market indices at Jordan's Amman stock exchange

Using daily data on five sectoral indices from 2006 to 2014, this paper aims to investigate the possibility of fractional integration in sectoral returns (and their volatility measures) at Jordan's Amman stock exchange (ASE). Empirical analysis, using the log-periodogram (LP) and local whittle (LW) based semi-parametric fractional differencing techniques suggest that all sectoral returns at ASE exhibit short memory. However, in the case of volatility measures, we found evidence of long memory. Following the recent literature that argues that structural breaks in a time series could also explain the presence of long memory, we tested the volatility measures for the presence of structural breaks. We found that long memory in some volatility measures could be attributed to the presence of structural breaks. Furthermore, using impulse response functions (IRF) based on ARFIMA, we found that shocks to sectoral returns at ASE exhibit short run persistence, whereas shocks to volatility measures display long run persistence.     

新形势下中国林产品贸易的困境与对策探讨

近年来,国际环保主义的盛行和消费者环保意识的提高,不仅催生了以森林认证与产销监管链认证为代表的绿色贸易条件,也促使各主要原木生产国采取各种政策限制木材等原材的出口,美国也修订了《雷斯法案》对贸易中的非法采伐进行限制。林产品贸易所面临的国际环境更加复杂多变。本研究从贸易模式、出口集中度、产业集中度三个角度剖析了中国林产品贸易面临的困境,并提出了相应的对策。     

林权确认的习惯法之立法完善与法理——以锦屏文书为例

述评新中国成立以来的林权制度演变,考察了林权确认的习惯法与国家法之间的冲突。基于法的价值论,认为林权确认的习惯法具有较之国家立法更优位的价值,更能满足解决林权纠纷的需要。指出对其进行立法完善的两种方式及相关法理思考。     

Stochastic equilibria of an asset pricing model with heterogeneous beliefs and random dividends

We investigate dynamical properties of a heterogeneous agent model with random dividends and further study the relationship between dynamical properties of the random model and those of the corresponding deterministic skeleton, which is obtained by setting the random dividends as their constant mean value. Based on our recent mathematical results, we prove the existence and stability of random fixed points as the perturbation intensity of random dividends is sufficiently small. Furthermore, we prove that the random fixed points converge almost surely to the corresponding fixed points of the deterministic skeleton as the perturbation intensity tends to zero. Moreover, simulations suggest similar behaviors in the case of more complicated attractors. Therefore, the corresponding deterministic skeleton is a good approximation of the random model with sufficiently small random perturbations of dividends. Given that dividends in real markets are generally very low, it is reasonable and significant to some extent to study the effects of heterogeneous agents’ behaviors on price fluctuations by the corresponding deterministic skeleton of the random model.     

福建台资森林旅游度假产业发展研究

福建是中国重要林区,森林旅游资源十分丰富。近几年,正在大力发展森林旅游度假产业。台湾森林度假产业较为成熟,开发和管理技术先进,资金丰厚。积极吸引台资台商进入福建相关开发领域有着相当积极意义。本文着重以详实的资料数据,对当前福建台资森林旅游度假产业的整体开发和运营状况作出分析,指出问题所在并提出建议。     

中美木质林产品产业内贸易的实证研究——基于1992—2009年的进出口贸易数据

采用UNcomtrade数据库的中美木质林产品贸易数据,利用G-L指数、G-L修正指数、Aquino指数、Brülhart边际产业内贸易指数及Thom&McDowell水平型和垂直型产业内贸易指数,对1992—2009年中美木质林产品产业内贸易的水平和结构进行实证分析。结果表明:中美木质林产品产业内贸易水平总体较低,贸易方式仍以产业间贸易为主;中美木质林产品贸易的增长由产业间贸易和产业内贸易共同引发;产业内贸易方式以垂直型产业内贸易为主。     

《森林法》修改应该厘清森林的法律概念

我国《森林法》的修改面临很多问题。其中有一项非常重要而且应当给与高度关注的事是厘清森林的法律概念。梳理与之有关概念。譬如森林、森林资源、林地、林木、林权、集体林权、林地等。对于众多有关森林的法律概念,我们应该通过明晰森林的概念将各个相关的概念衔接起来以便理顺各种关系。     

股市有免费午餐吗——一个基于随机过程的理论分析

关于股市是否存在＂免费午餐＂,理论存在着截然不同的观点。一些经济学家依据＂有效市场假说＂,认为＂天下没有免费的午餐＂。然而,近年来人们逐渐认识到,在有关金融市场的理论模型中,某些形式巧妙的＂免费午餐＂是可以得到的。这一结果与基本的经济学原理相冲突,一些经济学家对解释这一有趣的问题做出了努力。本文从股票回报率随机波动的假设出发,利用伊滕定理,在关于投资组合回报率大于政府债券回报率的概率计算基础上,推导出股市存在免费午餐的条件,并对每一因素进行了分析和概率计算。在此基础上,对投资者提出了理性投资建议。