农业纵向一体化经营与农户横向一体化合作——我国“三农问题”及其出路解析

“三农”问题即“农村、农民、农业”问题.从农业的特殊性出发,认为通过实现农业纵向一体化经营、大力发展农户横向一体化合作经济组织是发展农业、保护农民利益、维护农村稳定、真正做到“农业增产、农民增收”的有效途径.     

风险规避型供应链的收益共享机制研究

探讨了由风险规避型零售商与风险规避型供应商组成的两级供应链协作激励问题.首先研究了Stackelberg主从对策模型下风险规避型零售商与风险规避型供应商的决策行为,并分析了双方的风险规避系数对双方决策行为的影响.然后,研究了垂直一体化模型下风险规避型供应链的决策行为,同样分析了双方风险规避系数对供应链决策行为的影响程度.最后,提出采用收益共享契约机制来协调该供应链.并通过数值实验进一步分析供应商与零售商的风险规避系数对双方的决策行为及收益共享系数的影响程度.     

Assortment Planning for Vertically Differentiated Products

We consider the problem of a retailer managing a category of vertically differentiated products. The retailer has to pay a fixed cost for each product included in the assortment and a variable cost per product sold. Quality levels, fixed, and variable costs are exogenously determined. Customers differ in their valuation of quality and choose the product (if any) that maximizes their utility. First, we consider a setting in which the selling prices are also fixed. We find that the optimal set of products to offer depends on the distribution of customer valuations and might include dominated products, that is, products which are less attractive than at least one other product, on every possible dimension. We develop an efficient algorithm to identify an optimal assortment. Second, we consider a setting in which the retailer also determines the selling prices. We show that in this case the optimal assortment does not include any dominated product and does not vary with the distribution of customer valuations when there is no fixed cost. We develop several efficient algorithms to identify an optimal assortment and optimally price the products. We also test the applicability of our methods with realistic data for two product categories.     

Vertical foodweb structure of freshwater zooplankton assemblages estimated by stable nitrogen isotopes

Although theoretical foodweb models predict the presence of only three to four trophic categories, estimation of “potential” vertical foodweb structure from species lists and inferred feeding interactions suggest that as many as 7 trophic categories can occur in the pelagic foodwebs of North American glaciated lakes. A compilation of data on the nitrogen isotopic composition of zooplankton from 46 Canadian Shield lakes suggested the average existence of one “realized” trophic category in addition to that of filter-feeding, herbivorous cladocerans. When phytoplankton, planktivorous invertebrates, and plantivorous and piscivorous fish are included, the vertical foodweb structure in the pelagic zones of these lakes are greater than those hypothesized from some theoretical models.     

地区垂直专业化发展——行业和省份差异的比较

随着国际分工格局的演化,尤其是近年来国际垂直专业化分工的发展,其对我国经济发展的影响作用也变得越来越突出。基于双边贸易发展数据,通过修正的引力模型,从我国省级层面重点关注了不同行业和地区在参与国际垂直专业化分工过程中,相关重要因素的影响特点和一般规律。主要结论表明：地区市场规模、要素禀赋和经济地理因素均有显著影响,且这种作用因行业和地区发展差异而表现出了显著的不同。     

中国木质林产品产业内贸易的实证研究

产业内贸易是国际贸易研究的热点问题之一。本文在介绍中国木质林产品贸易现状的基础上,从实证的角度分别研究了中国各类木质林产品的产业内贸易指数,以及中国木质林产品的水平型和垂直型产业内贸易指数,最后给出了相应的对策和建议。     

社会群体多维剥夺感模型及应用

相对剥夺感研究对于构建和谐社会具有重要的理论和现实意义。本文首先综述分析了社会个体单维剥夺感模型(SISDM)、社会个体多维剥夺感模型(SIMDM)和社会群体单维剥夺感模型(SGSDM)等社会剥夺感研究领域的三大模型;然后,本文在Betti和Verma提出的社会个体多维剥夺感模型以及Elena和Lius等人提出的社会群体单维剥夺感模型基础上,建立了综合考虑横向和纵向剥夺感的社会群体多维剥夺感模型。最后,本文通过实证表明,新模型能够客观全面地反映社会群体的实际状况,可以为和谐社会建设提供客观的决策依据。     

电力市场结构转换的经济分析

电力市场结构转化是指电力市场从一种结构形式转为另一种结构形式,其实质是通过电力企业市场关系的调整来改变市场的垄断与竞争程度,达到改善市场运行绩效的目的.根据影响程度和电力市场的特点,电力市场结构转换可区分为两种典型的类型:纵向结构转换和横向结构转换.     

旅游企业一体化的边界分析

一体化行为作为一种高级化的竞争战略在给旅游企业带来快速发展的同时也产生了诸多问题。本文从经济学的角度深层剖析了旅游企业一体化扩张的影响因子,然后在此基础上构筑边界模型,深入研究了一体化扩张的最优规模和最优边界点,并对此展开了实证研究,为旅游企业一体化的实践活动提供理论指导。     

竖直矩形通道降膜吸收器热质性能的试验研究

试验研究了溴化锂水溶液沿竖直矩形通道降膜吸收过程的传热传质情况。结果表明,溴化锂水溶液降膜流量、吸收压力、溶液进口浓度及进口温度对总传热系数、平均降膜吸收率的影响比较大。