农产品供应链重构风险传导SIR建模与仿真研究

[目的]利用动力学SIR模型模拟农产品供应链重构内生风险传导过程,以期在有效把握核心重构风险传导规律基础上为整体管控重构进程风险提出前瞻性思路。[方法]基于农产品供应链重构风险整体构架和重构进程风险传导复杂网络,以湖北省243家大型连锁超市生鲜农产品供应链2007—2017年重构样本数据为研究对象,建立重构进程内生风险传导SIR模型和规划演化模式,利用Matlab软件对模型仿真得到有效管控状态下演化趋势。[结果]在以战术性重构为主导组织结构战略性重构中进程风险传导安全边际X1s超过50%,决定了其净风险阈α0(i)、β0(i),相应的业务单元和功能模块重构进程风险预警和风险恢复能力提高值是主控指标,对进程风险传导感染率x1(i)和恢复率x2(i)起主导作用。[结论]近年来土地流转驱动农产品供应链重构中组织结构重构整体具有战略性,在以战术性重构为主导风险传导管控中重点应加强业务单元和功能模块重构进程在重构易感状态(S)、感染传播状态(I)管控能力,能有效降低波动幅度。     

基于解释结构模型的茶叶品牌发展策略——以陕西汉中茶产业为例

以解释结构模型为工具,结合具体案例,总结了影响茶叶品牌发展的因素,如企业经营模式、市场信息、企业广告促销、政府的宣传引导、目标市场和市场定位、旅游资源开发、茶叶品质、地区性标准、茶叶物流体系、农业种植规范性、茶叶加工技术、良种推广等。分析了其相互影响关系,建立茶叶品牌发展的解释结构模型。并以此为基础,探索了改变茶叶企业的经营模式、健全现代物流体系、建立有效的市场信息平台和信息系统、建立地区性标准、建设政府平台等茶叶品牌发展的策略性问题。     

Ranking Crop Yield Models: A Comment

This comment discusses key specification issues that may have affected the performance and, therefore, the ranking of parametric models that were compared in a recent AJAE article. A procedure to obtain the most flexible parametric model specification possible, given the particular probability distribution function on which the model is based is presented. These specifications also allow for standardized and, therefore, more valid comparisons across parametric models that are based on different probability distributions. Finally, the comment cautions against generalization of the rankings in that AJAE article and recommends that these more flexible specifications be adopted in future comparisons and applications.     

基于结构方程模型的失地农户可持续生计的影响机理研究——以兰州市安宁区为例

[目的]通过探讨社会资本、人力资本、资金资本、物质资本4种常见生计资本及失地农民因征地补偿所特有的自然资本补偿对失地农户生计可持续性直接影响路径和间接影响途径,以期为其他生计研究及政府决策提供参考。[方法]文章基于甘肃省兰州市安宁区入户调查数据,采用熵值法从失地农户家庭年人均可支配收入、生计多样性、保险覆盖率及家庭劳动力就业率4个角度构建失地农民可持续生计评价体系,并运用结构方程模型中路径分析方法,定量分析生计资本对被失地农户可持续生计影响机理。[结果](1)人力资本、自然资本补偿和资金资本是主要直接驱动因素,对安宁区失地农户生计可持续性存在显著的正向直接影响;(2)物质资本和社会资本主要通过间接路径对可持续生计产生有限的影响;(3)人力资本、自然资本补偿与其他3种生计资本之间存在多种内在影响,最终通过资金资本对生计产生的间接效应。[结论]针对失地农户的可持续生计分析,应使用自然资本补偿替代自然资本,5项生计资本对于该群体生计可持续性影响在程度以及驱动路径上存在显著差异。     

个人账户可继承性与计发月数内在关系的定量分析

计发月数是我国基本养老保险体系中个人账户的关键参数，本文通过构建包含继承份额的个人账户精算模型，修正了计发月数的计算公式，得到个人账户收支平衡的判别定理。研究表明，忽略可继承性会严重低估计发月数，并产生大量资金缺口；计发月数与期望寿命无直接关系；提高退休年龄不一定能增强支付能力；提高投资收益率，或降低计发月数并合理控制收支差额，是当前协调个人账户养老保障和财务支付能力的重要办法。     

Climate Change Policy Options for Asian Economies: Findings from an Integrated Assessment Model

This study outlines potential futures for the global economy through the 2050 with a specific focus on the countries of Asia. With underlying assumptions about population and output growth, a baseline scenario assesses the growth of greenhouse gas emissions and the ensuing impacts on the climate. Under the baseline scenario, Asia's high growth leads to a strong rotation in global output and emissions by the year 2050. The analytical framework traces back the changes in temperature to economic damages – limited to the agricultural sectors. Parts of Asia are likely to see much higher dependence on food imports as a consequence of these damages. Various carbon tax scenarios are implemented to assess the potential for reducing carbon emissions. Because of the structure of their economies, Asian countries are likely to bear the greatest burden in reducing emissions in an efficient global tax scheme, but there is significant scope to ease this burden through financial transfers.     

基于OPNET的混合关键性网络建模与仿真分析

混合关键性网络是一种新型的通信架构,可以满足非实时性和实时性业务的需求。为分析其网络性能,提出在OPNET网络仿真环境中建模的方法。以开放式系统互联模型为基础,采用层次化建模,构建网络的节点模型和进程模型。该模型考虑了事件触发和时间触发消息的特点,通过设计调度算法和容错方式,实现了仿真实验的灵活配置和端到端延迟抖动等性能指标的验证。对仿真结果的性能分析表明,混合关键性网络能够保证实时业务的确定性以及兼容标准以太网的非实时业务。     

Cultural Consonance in Leisure,Leisure Satisfaction,Life Satisfaction,and Self-Rated Health in Urban Taiwan

The purpose of this study threefold: to determine whether a shared cultural model of the importance of a set of leisure activities to a good leisure life existed in urban Taiwan, the degree to which cultural consonance in leisure mediates the relationship between leisure constraints and leisure satisfaction, and the degree to which leisure satisfaction affects life satisfaction and self-rated health. Results indicate that a cultural model of the importance of leisure activities to a good leisure life existed among sample members. Second, higher levels of self-reported participation in leisure activities that are culturally agreed upon as more important for a good leisure life are more strongly associated with leisure satisfaction than are activities culturally agreed upon as less important. Finally, leisure satisfaction strongly predicts both life satisfaction and self-rated health.     

What do professional forecasters actually predict?

This paper studies what professional forecasters predict. We use spectral analysis and state space modeling to decompose economic time series into trend, business cycle, and irregular components. We examine which components are captured by professional forecasters by regressing their forecasts on the estimated components extracted from both the spectral analysis and the state space model. For both decomposition methods, we find that, in the short run, the Survey of Professional Forecasters can predict almost all of the variation in the time series due to the trend and the business cycle, but that the forecasts contain little or no significant information about the variation in the irregular component.     

Empowerment and resident support for tourism in rural Central and Eastern Europe (CEE): the case of Pomerania,Poland

Despite empowerment being a crucial component of sustainable tourism, few scholars have quantitatively operationalized empowerment and looked at how it applies to rural societies within the post-communist European Union (EU) member states. Knowing the high priority of sustainable rural development goals within the EU, empowering residents within these post-communist societies has become a pertinent issue especially where those societies appear more reluctant to engaging in democratic ways of decision-making. In response to this gap, this study tests the cross-cultural validity of the Resident Empowerment through Tourism Scale, and then evaluates how empowerment predicts residents’ support for tourism within the municipality of Choczewo, Pomerania, Poland. Using a theoretical perspective that blends Social Exchange Theory with Weber's Theory of Formal and Substantive Rationality, these non-economic empowerment dimensions are coupled with a measure of resident perceptions of economically benefiting from tourism to see if rural residents in Choczewo, Poland, are more swayed by the economic or non-economic benefits of tourism. Results show that residents within this Central and Eastern Europe setting are more influenced by the pride and self-esteem boost associated with psychological empowerment and the perceptions of increased community cohesion (i.e. social empowerment) than the economic promises of tourism.