考虑消费者有机产品偏好的生鲜农产品供应链均衡研究

针对普通农产品和有机农产品同时生产销售的现实状况,利用变分不等式理论构建了考虑消费者有机产品偏好的生鲜农产品供应链网络均衡模型,并通过数值算例探讨了消费者有机产品偏好及其他影响因素对供应链网络成员生产销售决策及利润的影响.研究结果表明,随着消费者有机产品偏好的提升,生产和销售有机农产品有助于生产商和零售商实现增收,但生产商可能会经历波折;降低有机农产品生产成本能够有效促进有机农业的发展;树立有机农产品的良好品牌形象增强其价格竞争力对供应链各方均有利;产量变化及需求波动都将对市场和各方利润造成较大影响.研究结论对相关企业的决策和相关领域的研究有一定借鉴意义.     

Realized Volatility Forecasting of Agricultural Commodity Futures Using Long Memory and Regime Switching

We investigate the dynamic properties of the realized volatility of five agricultural commodity futures by employing the high‐frequency data from Chinese markets and find that the realized volatility exhibits both long memory and regime switching. To capture these properties simultaneously, we utilize a Markov switching autoregressive fractionally integrated moving average (MS‐ARFIMA) model to forecast the realized volatility by combining the long memory process with regime switching component, and compare its forecast performances with the competing models at various horizons. The full‐sample estimation results show that the dynamics of the realized volatility of agricultural commodity futures are characterized by two levels of long memory: one associated with the low‐volatility regime and the other with the high‐volatility regime, and the probability to stay in the low‐volatility regime is higher than that in the high‐volatility regime. The out‐of‐sample volatility forecast results show that the combination of long memory with switching regimes improves the performance of realized volatility forecast, and the proposed model represents a superior out‐of‐sample realized volatility forecast to the competing models. Copyright © 2016 John Wiley & Sons, Ltd.     

基于利他偏好的鲜活农产品供应链决策研究

本文考虑供应链成员的利他偏好以及鲜活农产品的新鲜度和运输损耗特性,建立了鲜活农产品供应链决策模型.分别研究了供应商具有利他偏好、销售商具有利他偏好以及双方同时具有利他偏好时的供应链决策,得到了采购量和批发价格的最优解析解,进而分析了利他偏好对供应链决策以及供应链效率的影响.研究结果表明,利他偏好行为能够显著影响供应链的最优决策,且当双方均具有利他偏好且利他偏好在一定范围内时,供应链成员的利他偏好能够提高鲜活农产品供应链的效率.较高的供应商利他偏好能够提高供应链的效率,而较高的销售商利他偏好却会降低供应链的效率.另外,研究结果也表明,新鲜度因子和运输有效因子对最优决策和供应链利润也有明显影响.最后以数值分析说明研究结果的正确性.     

论高校科技成果的推广应用

本文论述了科技成果这种技术商品的价值、使用价值及交换价值,并探讨了科技成果转化为社会生产力的各种可能途径。提出了高校科技成果推广应用的正确方式。     

甘肃省地貌特征对农业可持续发展的影响

在分析甘肃省的地貌特征及其对农业生产的影响的基础上,论述了地貌与土壤侵蚀的关系,并指出坡度大、降水强度大、植被稀疏、地表物质疏松和大风是造成农业生态环境脆弱的主要原因,而人类活动的不合理则使本已脆弱的生态环境更趋恶化．最后,根据甘肃省的地貌格局,提出促进农业生态环境良性发展的根本措施：因地制宜发展与当地生态环境相适应的绿色产业,以确保农业生态环境良性发展;提高农业生产的集约化水平．     

农科专业课程音像资料的开发与应用

针对当前职业教育中农科课程发展的现状和未来发展趋势以及信息化制作技术的变化,对农科课程音像资料设计与开发的方向、制作环境要求以及音像资料的利用、管理、评价等方面进行了探讨。     

Forecasting commodity prices: GARCH,jumps, and mean reversion

In examining stochastic models for commodity prices, central questions often revolve around time‐varying trend, stochastic convenience yield and volatility, and mean reversion. This paper seeks to assess and compare alternative approaches to modelling these effects, with focus on forecast performance. Three specifications are considered: (i) random‐walk models with GARCH and normal or Student‐t innovations; (ii) Poisson‐based jump‐diffusion models with GARCH and normal or Student‐t innovations; and (iii) mean‐reverting models that allow for uncertainty in equilibrium price. Our empirical application makes use of aluminium spot and futures price series at daily and weekly frequencies. Results show: (i) models with stochastic convenience yield outperform all other competing models, and for all forecast horizons; (ii) the use of futures prices does not always yield lower forecast error values compared to the use of spot prices; and (iii) within the class of (G)ARCH random‐walk models, no model uniformly dominates the other. Copyright © 2008 John Wiley & Sons, Ltd.     

陕西省农业生态安全定量评价及其发展趋势分析

应用层次分析法建立了陕西省农业生态安全综合评价的指标体系,基于熵值法的综合指数评价法对陕西省农业生态安全从时间尺度上(1995～2004年)进行了定量评价和动态趋势的分析,结果表明该区域内的农业生态安全综合水平在不断提高,但10年来一直都处于很不安全的状态.简析了陕西省农业生态安全存在的主要问题,并提出其发展的对策.图4,表3,参12.     

基于良好农业规范(GAP)的蔬菜种植地系统评价方法

针对良好农业规范(GAP)在蔬菜基地应用中的种植地评价问题,提出了蔬菜种植基地农产品安全评价指标体系.应用层次分析法(AHP)分析得到各个评价指标的权重.给出了基于二元语义语言信息处理的系统评价方法和计算步骤,最后结合出口菠菜备案基地的农产品安全评价进行了实例分析.图1,表2,参9.     

潍坊市农业剩余劳动力内部转移的非均衡性

农业劳动力的过剩问题一直是困扰中国经济发展的一个重大问题，以潍坊市作为研究对象，选取了与劳动力转移密切相关的6个指标，运用聚类分析方法，探讨了潍坊市内部各县市区之间农业剩余劳动力的转移情况，发现转移存在着明显的非均衡性。