关键词： 中央银行   经济模型   货币政策   VAR模型   DSGE模型   LSE形式模型  

摘要： 本文介绍了国内外中央银行开发和使用的主要经济模型 ,比较了各经济模型的优缺点 ,并讨论了中央银行经济模型关注的主要方面。另外 ,从经济分析、预测及货币政策决策的角度介绍了中央银行在模型的开发、维护及应用等方面情况。

关键词： breeding   economic evaluation   feed intake   growth models   pigs  

摘要： Economic weights are obtained for feed intake using a growth model and an economic model. The underlying concept of the growth model is the linear plateau model. Parameters of this model are the marginal ratio (MR) of extra fat and extra protein deposition with increasing feed intake (FI) and the maximum protein deposition (Pd-max). The optimum feed intake (FI0) is defined as the minimum feed intake that meets energy requirements for Pd-max. The effect of varying FI and MR on performance traits was determined. An increase in FI results in a larger increase in growth rate with lower MR. For a given MR, feed conversion ratio is lowest when FI equals FI0. Lean meat percentage (LMP) is largest for a low MR in combination with a low FI. The decrease in LMP with higher FI is largest when FI exceeds FI0. Economic weights for FI, MR and Pd-max depend on FI in relation to FI0. Economic weights for FI are positive when FI is less than FI0 and negative when FI is larger than FI0. The MR has only then a negative economic weight, when FI is below FI0. Economic weights of FI and MR have a larger magnitude with lower MR and lower FI. In contrast, economic weights for growth rate and FI derived from the economic model only change in magnitude and not in sign with different levels of these traits. The economic model always puts a negative economic weight on FI since it expresses profit due to a decrease in FI with constant growth rate and LMP. This holds the risk of continuous decrease in FI in pig breeding programs. In contrast, the use of growth models for genetic improvement allows direct selection for an optimum feed intake which maximizes feed efficiency in combination with maximum lean meat growth. It is concluded that recording procedures have to be adapted to collect the data necessary to implement growth models in practical pig breeding applications.

关键词： evolutionary spatially distributed markets   time-dependent variational inequalities   supply and demand excesses  

摘要： In this paper we aim to present a model of spatially distributed economic markets under the assumptions that each demand market becomes a supply market after the time Delta. This problem is expressed by a time-dependent variational inequality for which we provide existence theorems and an example of computational procedure.

关键词： 计量经济模型   西方化   数学化   假设条件  

摘要： 计量经济模型是经济理论研究和经济决策中一种十分重要的方法。然而 ,我国经济学界对计量经济模型还存在诸多认识上的误区。本文从模型与西方经济学的关系、模型与数学的关系、模型的假设条件以及解释变量的选择和模型对定性因素的处理等五个方面进行了分析 ,认为只有全面、客观地认识计量经济模型才能有利于经济学研究的健康发展。

关键词： 物流包装   企业   专业化   经济学  

摘要： 　分析企业专业化生产与规模经济的关系,其价值对企业专业化生产物流包装的经济学思考具有重要的指导意义。

关键词： 数理经济模型   经济效率   度量方法   消费者剩余   等价变量   补偿变量  

摘要： 一、经济效率的定义

关键词： 市场经济模型   消费者行为   信用等级   消费信贷   偏好对应   下半连续   经济均衡  

摘要： 文章构造了一个市场经济模型,在此模型中,消费者能根据自身的信用等级来利用消 费信贷,其偏好对应是下半连续的.文章还证明了此经济存在均衡.

关键词： Gompertz增长   定性分析   Gompertz模型   价格   供求   捕获模型   数学生物经济模型  

摘要： 　对种群服从Gompertz增长的开放式生物资源建立了价格随供求而变化的捕获模型,并对其进行了详细分析.讨论了平衡点的存在性、稳定性及极限环的不存在性,从生态学和经济学的角度对所得到的结果做出了解释.探讨了关于生物资源开发的相关问题,为生物资源的实际开发与管理提供了必要的理论依据.

关键词： 中国   甲基溴   经济模型   保护地作物   农业生产   淘汰方案   生态环境  

摘要： 中国在甲基溴使用方兴未艾之际 ,就面临着要签署条约 ,淘汰使用甲基溴 ,势必对中国的相关农业生产 ,尤其是保护地农作物生产产生重大影响。本文设计了一个模型 ,并利用实地调查数据在三套淘汰甲基溴方案中评估这种影响。研究结果分析表明 ,执行第二种淘汰方案 ,即 2 0 0 5年以后的甲基溴总用量年度递减的速度从小到大逐年增加 ,但给定加速度为常数 ,直至 2 0 1 5年时为 0 ,对我国蔬菜、草莓、中草药 (含人参 )生产影响最小。

关键词： treatment   wetlands   domestic   cost   economic model  

摘要： Total system life costs (capital cost and ecological based on released pathogens) were modeled for two-cell domestic treatment wetland systems and compared to costs of traditional and emerging technology systems. Small treatment wetlands that were operationally effective for 20-years had net present value (NPV) costs $500-3000 less than those of sand filter systems. The same treatment wetlands were modeled as releasing similar to 4 times pathogens, thus having a much higher ecological cost than sand filter systems. Wetland systems modeled using the highest possible pathogen treatment efficiencies still released similar to 2 times the pathogens of sand filter systems. Treatment wetlands must function a minimum of 10 years before replacement in order to remain equivalent in cost to a sand filter lasting 20-years using a 6.25% discount rate. The maximum allowable installation costs for any alternative system (with no annual expenses) were $6675-7700 if required to be equal in total system NPV costs to wetlands. NPV costs were found to be particularly sensitive to uncertainties in installation and maintenance costs. Modeling indicated that the capital savings realized using wetland systems could be used to modify the simple 2-cell design such that both capital and ecological loads delivered to the environment could be minimized. Wetlands may provide a more sustainable option for communities if effluent is centralized and treated in an appropriately scaled wetland system. (C) 2003 Elsevier Science B.V. All rights reserved.