水源地突发水污染政府应急预留水量需求预测

近年来,随着工业化和产业化的快速发展,水源地突发水污染事件频发。为应对紧急情况下的水资源非常规需求,保障经济社会稳定发展,政府需要安排一部分应急预留水量。如何合理预测政府应急预留水量的规模是一个值得探讨的课题。提出了一种基于案例推理技术的政府应急预留水量需求预测方法,具体思路是:借助于案例库,利用主成分分析法从众多影响水源地突发水污染事件的因素中提取出两两不相关的因子,以此作为案例的特征属性,基于加权曼哈顿距离测算相似度,依此得到匹配案例,进而测算政府应急预留水量。以太湖流域常州地区水源地为例,进行政府预留水量需求量的预测与分析。该方法可以为政府应急预留水量的配置、储备等提供相关理论知识。     

河北省夏玉米需水量变化特征及未来可能趋势

基于1963—2015年近50年间河北省夏玉米主产区8个气象站点气象资料,采用联合国粮食与农业组织(FAO)推荐的Penman-Monteith模型和作物系数法计算夏玉米需水量,再结合《IPCC排放情景特别报告》中的两种排放情景RCP2.6(低排放情景)和RCP8.5(持续排放情景)预估的未来气候情景,探讨气候变化下未来河北省夏玉米需水量的时空演变规律。结果表明:1963—2015年河北省夏玉米需水量呈现下降趋势,在空间上大致以黄骅为高值中心,由东北向西南逐渐递减,并在邢台形成低值中心的分布特征;从未来气候变化情景来看,相对于基准时段(2015年),RCP2.6和RCP8.5情景下,在2020年、2030年、2050年、2070年未来4个典型年份夏玉米的需水量均表现出增加的特征。     

Economic development,food demand and the consequences for agricultural resource requirements: an application to Indonesia

We analyse food demand patterns of Indonesian households from a resource intensity perspective and quantify the impact of changed demand patterns on the use of three major resource inputs: fossil fuel; land; and water in agricultural production. Using Indonesian Family Life Survey data, 13 major food items (which constitute 70 per cent of food expenditure) are categorised into low, moderate and high resource intensity, and income elasticity and Engel curves are estimated for the period from 1997 to 2007. Our results show that income growth in Indonesia is associated with demand patterns that are more resource intensive. By 2007, per capita requirements of fossil fuel, land and water increased by 42.7 per cent (3.13 MJ), 44.9 per cent (1.24 m²) and 50.4 per cent (2.1 kL), respectively, relative to 1997. The results imply that, at least for Indonesia, changed food demand patterns resulting from economic development will increase the demand for natural resources substantially.     

A Meta‐Analysis on the Elasticity of Demand for Pesticides

There is an increasing policy interest in pesticide taxation schemes as a measure to reduce harmful effects of pesticide use. The effectiveness of such tax depends, however, on the price elasticity of demand for pesticides. Moreover, information on these demand elasticities and their determinants is of crucial relevance for policy‐making and normative modeling approaches. In this article, we present a meta‐analysis based on studies that have estimated pesticide demand elasticities in Europe and North America. Our meta‐analysis reveals that the own‐price elasticities of demand for pesticides are, with a median of ?0.28, significantly smaller than zero, but also significantly larger than ?1, i.e. to be inelastic. We find that the demand for pesticides for special crops is less elastic than that for arable and grassland. In addition, the demand for herbicides is more elastic than for other pesticides. Studies that consider only short‐term horizons and little flexibility for farmers to adjust to price changes generate significantly less elastic pesticide demands. The results also indicate that more recent studies identify lower pesticide price elasticities of demand. Furthermore, we find that peer‐reviewed studies tend to find more inelastic results compared to grey literature.     

东北三省煤炭资源供需形势分析

国家“十一五”规划纲要对东北地区工业的发展提出了新的要求,但是近年来东北三省的煤炭资源供给小于需求,并且缺口不断加大,按照东北三省“十一五”规划纲要的目标要求,采用万元GDP能耗法预测“十一五”期间东北三省的煤炭资源供需将趋于缓和,但是增加煤炭产量和减少消费的任务十分艰巨。     

基于消费者行为理论的森林食品产业发展潜力分析

文章运用经济学的消费行为理论,从消费者对森林食品的偏好分析入手,分析了森林食品具有二元价值结构的特征,推出大多数的消费者对森林食品具有超满足性消费偏好的特性,其效用函数有非1正实根。在此基础上,结合我国森林食品产业发展的特征,导出森林食品产业的需求模型。以期为森林食品产业组织的完善及竞争力的提升提供市场需求的理论分析依据。     

A Sample Selection Approach to Censored Demand Systems

The multivariate sample selection model is extended to a nonlinear equation system with partial selection and applied to household meat consumption in China. Elasticity estimates differ from those obtained from conventional maximum likelihood and Tobit estimates. Chinese meat products are gross complements while net substitution also exists in some cases.     

内需的扩大是增加还是减少出口？——基于异质企业视角的理论模型和实证研究

中国的贸易失衡表现为巨大的贸易顺差,有一种观点认为扩大内需可以减少出口,降低贸易失衡。本文在考虑企业异质性的基础上,对中国制造企业内需能否促进出口的作用进行了理论和实证分析。理论模型预测,如果企业生产率足够高,可以进行贸易,企业内需的增加总能促进出口数量和出口额的增加,且贸易成本的减小会促进这种效应。我们运用中国工业企业数据对这一推论进行了实证研究。我们首先利用半参数估计的Olley和Pakes(OP)方法估计企业生产率,然后控制企业生产率、企业要素禀赋、行业固定效应、地区固定效应和企业所有制的影响进行计量分析。实证结果发现,出口企业内需的扩大显著促进了企业的出口,而且处于规模经济行业的企业的这种作用更为显著,东部地区企业和国有企业的国内销售对出口的作用也高于其他地区和其他企业。另外,本文对不同出口规模的企业应用分位数回归方法发现,企业出口规模越大,企业内需对出口的作用越显著。     

农业专业合作社的融资供求衔接问题研究

农业专业合作社融资具有一般企业所不具有的特殊性。论文从理论角度分析了农业合作社融资次序的选择,认为通过正规金融实现合作社融资供求衔接的有效途径。在供求不平衡,传统信贷供给无法满足合作社融资需求的状况下,探索了“公司＋合作社＋农户”、“农业龙头企业＋担保公司＋合作社＋农户”、“政府＋农业生产基地＋农业企业＋合作社＋农户”三种农业产业链融资模式,并分析了其主要特点、优势以及主要风险,为合作社融资提供了新思路。     

Price Endogeneity and Food Demand in Urban China

Price endogeneity has been ignored in previous analyses of food demand in urban China. We exploit data provided by the China National Bureau of Statistics on agricultural commodity supply shifters and use reduced‐form price equations to account for price endogeneity. Applying our unique econometric approach to the analysis of provincial‐level food demand in China, we find strong statistical evidence of price endogeneity. Models that ignore price endogeneity result in substantially biased elasticities and misleading estimates of future food demand in China.