关键词： Multi-agent systems   Economic models   Pareto and Boltzmann-Gibbs distributions  

摘要： The one-dimensional deterministic economic model recently Studied by Gonzalez-Estevez et al. [J. Gonzalez-Estevez, M.G. Cosenza, R. Lopez-Ruiz, J.R. Sanchez, Physica A 387 (2008) 4637] is considered on a two-dimensional square lattice with periodic boundary conditions. [it this model, the evolution of each agent is described by a map Coupled with its nearest neighbors. The map has two factors: a linear term that accounts for the agent's own tendency to grow and an exponential term that saturates this growth through the control effect of the environment. The regions in the parameter space where the system displays Pareto and Boltzmann-Gibbs statistics are calculated for the cases of the von Neumann and the Moore neighborhood. It is found that, even when the parameters in the system are kept fixed, a transition from Pareto to Boltzmann-Gibbs behavior can occur when the number of neighbors of each agent increases. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Markov链   市场经济   价格   模型  

摘要： 对于市场经济中商品的价格、数量的变化规律及其最终趋势,利用Markov链建立了商品数量,价格及其相互关系的基本方程,描述市场经济中商品的价格,数量的变化规律及其最终趋势。最终的结论给出的是数量,价格处于某个状态的概率,具有一定的可信性。

关键词： Bio-economic model   Dynamic   Intramammary infection   Stochastic   Dairy cows  

摘要： Although the dynamics of transmission play an important role in the occurrence of intramammary infection (IMI), they have not been considered in previous models used to estimate the cost of IMI. The bio-economic model described includes within-herd dynamics of pathogen-specific IMI. The model simulated Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, and Escherichia coli IMI stochastically and estimated the cost of these IMI in a herd of 100 dairy cows in a situation where a quota is applied to milk production. A Reed-Frost model was used for S. aureus, S. uberis, and S. dysgalactiae IMI and a Greenwood model for E coli IMI. Economic analysis was conducted per pathogen for clinical and subclinical IMI. The parameters used in the model were based on the literature and were deemed credible and valid. Median annual incidence of clinical and subclinical IMI for all pathogens varied considerably. This variation was greatest for S. aureus IMI. The annual incidence of IMI in a herd of 100 dairy cows caused by S. aureus varied between 0 and 88 cases, with a median of 5 cases and the 5th and 95th percentiles of 0 to 36 for clinical IMI, and a median of 7 cases with the 5th and 95th percentiles of 0 to 52 for subclinical IMI. In consequence, the average total annual net costs also varied widely for S. aureus IMI. Clinical IMI costs were (sic) 1375, with the 5th and 95th percentiles of 0 to 4716 and subclinical IMI costs were (sic) 1219, with the 5th and 95th percentiles of 0 to 4030. The average annual net cost due to the 4 simulated pathogens combined was E 4896 and varied from (sic) 915 to (sic) 11,287 in a herd of 100 dairy cows. The bio-economic model developed for this study will be utilized as a tool to investigate the economic impact of management of pathogen-specific IMI. (C) 2009 Elsevier B.V. All rights reserved.

关键词： 鲐鱼   生物经济模型   大型灯光围网渔业   东黄海  

摘要： 鲐鱼是我国近海重要经济鱼类,如何综合考虑生物、经济和社会效益来科学制定渔业管理目标是确保该资源可持续利用的重要研究内容。根据中、日、韩三国鲐鱼围网生产作业数据及相关经济数据,构建基于Schaefer剩余产量的生物经济模型,探讨不同管理目标下的产量及其对应捕捞努力量,以及1年(短期)、5年(中期)和10年(长期)的经济效益和资源状况。结果表明,最大持续产量(MSY)、最大经济产量(MEY)和生物经济平衡点(BE)对应的捕捞努力量(以我国大型灯光围网的单位网次产量为准)分别为23964网次,13816网次和27631网次,其对应的第1年产量和利润分别为39.29万t和5.56亿元,22.65万t和3.20亿元,及45.30万t和6.41亿元;前5年累计的产量和利润分别为181.88万t和19.78亿元,131.04万t和25.81亿元,及192.10万t和13.12亿元;前10年累计的产量和利润分别为354.62万t和34.53亿元,272.32万t和57.24亿元,及362.08万t和14.07亿元。研究表明,以BE为管理目标则其短期经济效益为最大,而以MEY为管理目标则其长期经济效益为最大。探讨了不同管理方法对鲐鱼渔业所产生的影响。

关键词： 事件   经济影响   直接经济影响   经济模型  

摘要： 经济影响一直是事件旅游研究中最受学者广泛关注的话题。虽然事件经济影响不是事件旅游文献中最早被研究的问题,但却是第一个被完整研究的主题。从1977年第一篇公开发表的关于事件经济影响研究的文章到现在,事件经济影响研究已有30多年历史,许多学者介入其中。但由于经济影响的复杂性,至今该项研究仍处于初级阶段,在概念界定、研究内容和方法方面还存在很多问题。本文通过对76篇事件经济影响的历史文献进行梳理,对事件经济影响研究的主要内容、方法和结论做了详细的介绍,以期为事件经济影响提供一个统一的评估框架,为致力于事件经济影响研究的学者提供比较完整的文献资料。

关键词： 计量经济模型   常参数   变参数   非参数   半参数  

摘要： 在计量经济建模过程中,参数形式的确定是最基本的步骤。从经济学实证研究的实践看,计量经济建模中应用最早、应用最多的为常参数形式,上个世纪60年代以后,又逐步发展出变参数形式、非参数形式和半参数形式。经过一个多世纪的发展,四种参数形式已经形成了一个有着严密的传承关系的体系。各种参数形式既相互关联,又具有各自的优缺点,有着不同的应用领域,呈现出从简单到复杂逐步演进的特点,有着较强的发展规律性。

关键词： 87.23.Kg Dynamics of evolution   89.65.Gh Economics   econophysics, financial markets, business and management   89.75.Fb Structures and organization in complex systems  

摘要： We show that a simple model of a spatially resolved evolving economic system, which has a steady state under simultaneous updating, shows stable oscillations in price when updated asynchronously. The oscillations arise from a gradual decline of the mean price due to competition among sellers competing for the same resource. This lowers profitability and hence population but is followed by a sharp rise as speculative sellers invade the large un-inhabited areas. This cycle then begins again. [ABSTRACT FROM AUTHOR]

关键词： DEEP-sea fisheries   NONFICTION  

摘要： The article reviews the book 'The Worldwide Crisis in Fisheries: Economic Models and Human Behaviour,' by Colin W. Clark.

关键词： ECONOMIC models   STABILITY (Mechanics)   SYMMETRY (Physics)   DIMENSIONAL analysis   COMBINATORIAL dynamics   CHAOS theory   BIFURCATION theory  

摘要： In this paper, we will propose a generalized Cournot duopoly model with Z(2) symmetry. We demonstrate that cost functions incorporating an interfirm externality lead to a system of couple one-dimensional maps. In the situation where agents take turns, we find in an analytic way that there coexist multiple unstable/stable period-2 cycles or synchronized/asynchronized periodic orbits. Coupling one-dimension chaos can be observed. In a more general situation, where agents move simultaneously, a closer analysis reveals some well-known local bifurcations and global bifurcations which typically occur in two-parameter families of two-dimensional discrete time dynamical systems, including codimension-one (fold-, flip-, Neimark-Sacker-) bifurcations, codimension-two (fold/flip, 1:2 resonance, 1:3 resonance and 1:4 resonance) bifurcations, and hetero-clinic, homo-chilic bifurcations, etc. Multistability, including the coexistence of synchronized/asynchronized Solutions are also discussed. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： 经济史   经济学家   经济世界   工业革命   经济模型   研究生教育   统计方法   专业化  

摘要： 上帝创造经济世界的各种规律，似乎只是为了和经济学家们开个玩笑，让他们白费力气。在经济学领域，人们描述和预测经济世界的能力只是在1800年前后达到顶峰。工业革命后，利用经济模型来预测各国、各地收入和财富差异的能力越来越差。经济学变得更专业化。不断深化的研究生教育，培养了大批对复杂的经济模型和统计方法了如指掌的高水平经济学家。但是，自工业革命以来，我们陷入了一个陌生的新世界。