企业现金流转系统动态仿真研究

本文运用系统动力学方法分析了企业现金流转问题的基本特征。针对一特定民营企业建立了企业现金流转的系统动力模型，并在此基础上，设计四种仿真方案模拟了不同条件下企业现金流转的具体情况，以期为企业现金流以及企业的持续经营做一些有益的探索。     

Protecting Forests Through Farming. A Dynamic Model of Nontimber Forest Extraction

Forest resource extraction by local communities has been cited as a major impediment to the efficient management of protected forests. This paper develops a two sector dynamic model for farming and forest resource extraction by communities living in the forest periphery. The model assumes that land under forestry is constant and households allocate their time to farming and forestry. Comparative dynamic results suggest that higher prices for agriculture output, lower input prices, better knowledge of farming techniques and a lower discount rate may result in a higher equilibrium stock of forest resources. Tobit analysis with primary data collected from the Sinharaja forest in Sri Lanka provides supportive empirical evidence.     

Central bank interventions and jumps in double long memory models of daily exchange rates

In this paper, we estimate ARFIMA–FIGARCH models for the major exchange rates (against the US dollar) which have been subject to direct central bank interventions in the last decades. We show that the normality assumption is not adequate due to the occurrence of volatility outliers and its rejection is related to these interventions. Consequently, we rely on a normal mixture distribution that allows for endogenously determined jumps in the process governing the exchange rate dynamics. This distribution performs rather well and is found to be important for the estimation of the persistence of volatility shocks. Introducing a time-varying jump probability associated to central bank interventions, we find that the central bank interventions, conducted in either a coordinated or unilateral way, induce a jump in the process and tend to increase exchange rate volatility.     

中国绿色产业发展演进特征及数字普惠金融支持分析

为探究中国绿色产业发展现状、空间差异、分布动态演进及数字普惠金融支持效应,论文基于变异系数—层次分析法测度绿色产业发展水平,通过空间Moran’s I指数、Dagum基尼系数及Kernel密度估计分析其空间差异及分布动态,继而利用空间杜宾模型分析数字普惠金融对绿色产业发展的影响。结果表明,绿色产业发展水平正在快速提升,但存在明显空间差异及"俱乐部"发展特征,东、中、西部地区呈梯度递减演进趋势,且整体及东、西部地区具有明显多级分化现象;数字普惠金融能促进整体及东、中部地区绿色产业发展,对西部地区则有抑制作用。对此,应充分重视绿色产业发展的空间差异、分布特征及数字普惠金融异质性支撑作用,强化省份间的区域协调发展效应,实现绿色产业高质量发展。     

基于空间计量方法的城镇化动力实证研究——以环洞庭湖区域为例

在参考Cobb-Douglas生产函数构建的城镇化动力理论模型的基础上,使用空间计量方法对2000～2009年环洞庭湖区域城镇化动力进行了实证研究,结果显示:区域经济发展总体水平对城镇化有显著的正向促进作用,但呈逐年下降趋势;固定资产投资及流通产业发展对城镇化的推动作用较大,但仍不稳定;人力资本投资对洞庭湖区域城镇化的作用尚不显著。因此,要改变当前环洞庭湖区域城镇化动力不充足、不稳定的问题和促进湖区从"粗放城镇化"向"新型城镇化"转换,就必须主动对接"长株潭"城市群、深化分工和夯实产业基础、加大固定资产投资、充分发挥流通产业的先导作用并高度重视人力资本积累。     

基于SD模型的诸城市农业结构仿真优化研究

［目的］预测2017—2035年诸城市农业结构的变化趋势,对农业结构进行多情景优化仿真,提出优化调整建议。［方法］文章以山东省诸城市作为研究对象,将农业结构划分为种植、种养结合和加工休闲3个子系统,选取56个指标,运用多元统计回归分析等方法构建41个方程,建立农业结构系统动力学（System Dynamics,简称SD）模型,运用Vensim—PLE软件进行仿真优化分析。［结果］SD模型预测结果表明,到2035年,粮食作物播种面积1105万hm2,总产量8037万t,经济作物播种面积652万hm2,总产量15203万t; 生猪出栏量达到29615万头,家禽出栏量1105 231亿只,畜禽粪污利用率8792%; 农业总产值达到25132亿元,休闲农业产值6134亿元,食品加工业产值1 25263亿元。假设种植业生产中的农业科技投入增加2个百分点, 2035年粮食作物产量较优化前增加576万t; 经济作物产量较优化前增加2814万t; 假设有机肥施用补贴增加3个百分点, 2035年畜禽粪污利用率较优化前提高762个百分点; 假设农产品加工业的研发力度和科技投入增加1个百分点, 2035年食品加工产值较优化前增加73521亿元; 农产品加工业产值占农业总产值比值由优化前的325：1达到41：1。［结论］为进一步推进诸城市农业结构调整,迫切需要加大农业科技投入,完善有机肥扶持政策,培育种养结合新型经营主体,重点扶持培育加工龙头企业,发展现代化休闲农场,促进农业产业融合发展。     

Simulación de la tasa de reciclaje de productos electrónicos Un modelo de dinámica de sistemas para la red de logística inversa

Current trends in the development and innovation of information technologies and shorter life cycles of electronic products have resulted in the generation of large amounts of waste (e-waste) which can potentially cause environmental problems due to the toxicity of some of their components. The e-waste problematic has attracted the attention of governments, companies and consumers that look to identify strategies for the management and proper disposal of e-waste with the goal to protect the environment. This work uses the methodology of system dynamics to simulate how the rate of products returned by individuals and the amount of computers recovered in an open-loop reverse supply chain, varies under different scenarios. The simulated scenarios correspond to the possible combinations of five macro factors: rate of innovation and product life cycle, information available to consumers about e-waste recycling, legislation, e-waste programs structure along with diffusion and publicity efforts. The results of the simulation are relevant to identify over which factors it is convenient to intervene to increase the amount of recycled computers because this amount represents a reduction in the volume of e-waste and an enterprise opportunity to generate earnings from recycling computers.     

能源系统动力学应用研究综述

对系统动力学理论在国内外的发展过程以及其在不同领域的广泛应用进行研究,概括了能源系统动力学的实质是系统动力学理论与SD模型在分析各类能源问题的实证研究与应用,报告了能源系统动力学国内外研究现状,总结了系统动力学在能源领域的应用以及其对环境保护、经济发展、社会进步等方面的贡献,并在此基础上展望了能源系统动力学在大数据时代与数据挖掘及GIS等理论结合研究的方向.     

Household indebtedness in Korea: Its causes and sustainability

This paper investigates why household debt in Korea has increased so rapidly over the past decade and whether it is sustainable, adopting a multi-faceted approach which includes a time series analysis, a quantitative analysis based on household panel data, and an analysis using a debt dynamics equation derived from the household budget constraint. A regression analysis reveals that household debt growth has been significantly related to house price increases, banks’ lax attitudes toward household lending, and financial institutions’ favorable funding conditions. Also 70–80% of the total debt increase has been accounted for by high income or newly indebted households. The debt dynamics equation analysis shows that the rapid rise in the ratio of household debt to disposable income is attributable not only to the increase in household asset purchases but also to the dampened growth in disposable income and the reduced savings rate. The sustainability analyses indicate that Korean households’ debt sustainability is unlikely to deteriorate sharply within a short period of time unless two extreme scenarios, under which house prices decline by 5% a year over the next five years, or a significantly large macroeconomic shock similar to the 1997 crisis hits the economy, would be realized.     

CAFTA-DR Effects on FDI Inflows,Growth, and Distribution of the Workforce in Costa Rica: A System Dynamics Approach

As regional trading arrangements have spread, enlarged, and deepened over the last decades, the study of the relation between trade agreements and foreign direct investment (FDI) still presents difficulties due to the multi-dimensional character of such relationships. This article attempts to shed new light on how some of the Central American Free Trade (CAFTA) policies will impact FDI inflows on the manufacturing and agricultural sectors in Costa Rica. Specifically, we look at how the growth and distribution of the workforce is affected by the treaty. The results show that the agreement provisions will have a positive effect on FDI. From these results it is possible to estimate that in the long run, the implementation of CAFTA has a higher probability of generating the intended benefits. System dynamics modeling is used in this article.