生态农业模式构建与应用——以广饶县为例

本文从农业可持续发展、资源永续利用的原则出发,探讨了构建生态农业模式的原则,以山东省广饶县为例,系统分析了在该县构建和应用生态农业模式的优势条件和制约因素,具体论述了适合广饶县发展的三种生态农业模式:农—牧—沼型、上粮下渔型和草—畜—乳型生态农业模式。     

Economic Potential of Biomass Based Fuels for Greenhouse Gas Emission Mitigation

Use of biofuels diminishes fossil fuelcombustion thereby also reducing net greenhousegas emissions. However, subsidies are neededto make agricultural biofuel productioneconomically feasible. To explore the economicpotential of biofuels in a greenhouse gasmitigation market, we incorporate data onproduction and biofuel processing for thedesignated energy crops switchgrass, hybridpoplar, and willow in an U.S. AgriculturalSector Model along with data on traditionalcrop-livestock production and processing, andafforestation of cropland. Net emissioncoefficients on all included agriculturalpractices are estimated through crop growthsimulation models or taken from the literature. Potential emission mitigation policies ormarkets are simulated via hypothetical carbonprices. At each carbon price level, theAgricultural Sector Model computes the newmarket equilibrium, revealing agriculturalcommodity prices, regionally specificproduction, input use, and welfare levels,environmental impacts, and adoption ofalternative management practices such asbiofuel production. Results indicate no rolefor biofuels below carbon prices of $40 perton of carbon equivalent. At these incentivelevels, emission reductions via reduced soiltillage and afforestation are more costefficient. For carbon prices above $70,biofuels dominate all other agriculturalmitigation strategies.     

基于生态足迹模型的可持续性度量研究--以吉林省大安市为例

针对吉林省大安市发展现状和存在的严重生态环境问题,运用生态足迹模型,采用多源数据,首次对大安市生态环境的可持续发展状况进行了定量研究;在此基础上,运用相对指标法对可持续发展的量化结果进行分级。研究表明,2001年大安市的生态需求大于生态供给,生态呈现“供不应求”的局面,人均生态赤字为0.56hm2,处于弱不可持续发展状态。     

电子商务企业物流模式的经济学研究

电子商务企业对传统的物流提出了挑战．成为物流发展的强劲动力。本文从经济学理论角度对电子商务企业物流模式的选择进行了探讨：从对总成本的节约出发建立了企业自营与外包物流决策的成本模型．并分析了在电子商务的影响下该模型中成本因素的变化。得出第三方物流将是电子商务企业的好选择。     

一种机场抢修预置物资仓库选址模型

为进行空军机场抢修预置物资仓库精确选址;分析影响因素、确定主要研究对象,建立数学模型,提出求解选址问题的方法;通过理论证明与实例验证,证明了方法的准确与快捷;为空军机场抢修预置物资仓库的选址提供了一种更为科学、有效的方法.     

陕西省建筑业管理模式创新研究

针对陕西省建筑业中存在的问题，站在发展的角度对其管理模式的创新提出了一些设想及相应的措施。     

Analysis of Visitor Decision Making System When Visiting Natural Recreation Sites by Multinomial Logit Model

Multinomial Logit Model has analyzed the relationship between the frequency of visits to recreation areas and the motivational factors affecting the visits. Kastro Environment Preserving Site that is located in the Black Sea coast of Marmara region in Turkey, has been chosen as the site for this study. Kastro bay is a natural park that is visited only for recreational visits. The study has been conducted on a photogenic study group due to the proximity factor of Kastro bay close to Istanbul. Kastro bay is a popular recreational park due to its characteristic advantages such as a 200 m wide and approximately 2.5 km long beach and with its high quality vegetation. The vegetation type includes ash tree, oak tree, black pine, sand lily etc. Kastro bay is also the site for the Mediterranean seals (Monachus-monachus) which are at the level of extinction. Approximately 50,000 visitors visit the region during the months of July and August. It has been concluded that there is high direct correlation between the frequency of visits and the motivational factors. It has been determined that the visits are mostly based on the sea and the ecological tourism.Jel: O13, Q20, Q26, Q51, Q56, Q57     

装备维修器材分配供应方法研究

装备维修器材的分配供应是实现对部队维修器材保障的关键一环，本文通过分析其分配供应的具体过程，对每一环节建立了切合实际、方便操作使用的数学模型，可为装备维修器材保障业务人员提供科学的决策依据，从而达到军事效益和经济效益的双赢的目的。     

Simulation driven inferences for multiply imputed longitudinal datasets*

In this article, we demonstrate by simulations that rich imputation models for incomplete longitudinal datasets produce more calibrated estimates in terms of reduced bias and higher coverage rates without duly deflating the efficiency. We argue that the use of supplementary variables that are thought to be potential causes or correlates of missingness or outcomes in the imputation process may lead to better inferential results in comparison to simpler imputation models. The liberal use of these variables is recommended as opposed to the conservative strategy.     

CMM模型和我国软件业生产过程标准化

CMM模型是国际上最流行的一种软件生产过程标准。本文比较了国内外软件业生产过程标准化的现状,分析了阻碍我国软件业开展CMM评估的原因,并在此基础上,提出在我国推行CMM标准亟待解决的几个主要问题。