Leslie人口年龄结构模型的修正

Leslie人口年龄结构数学模型建立在没有人口流动的基础上,本文试图建立含人口迁徙因素在内的修正模型,并研究修正模型年龄结构的稳定性.     

中国经济增长对农村贫困减缓影响的实证研究

基于2007-2017年中国31个省际数据,通过构建面板平滑转换模型(PSTR)研究经济增长对贫困减缓影响的连续变化过程.研究结果表明:经济增长与农村贫困之间的关系呈现出非线性的特征.在模型的门槛值前后,经济增长对农村贫困程度的影响始终表现为抑制,说明了经济增长有助于农村贫困减缓.城乡收入差距和农业总产值都显著地起到了促进贫困减缓的作用.财政支农在短期内可促进贫困减缓,但统计上不显著,在长期内不利于贫困减缓.政府若长期通过财政支出扶持农村地区,可能会使农民对政府产生依赖和劳动惰性,从而不利于贫困减缓.     

基于高斯-泊松-莱斯利模型的中国人口预测与控制

针对中国人口现状和未来的发展趋势,提出了高斯-泊松-莱斯利模型,该方法全面考虑了人口年龄结构、人口性别比等因素,同时对成熟的莱斯利模型进行了优化改进.以此得到的分析结果可以为国家在人口问题方面的政策规划提出建设性的意见.     

农村人口结构变化对经济增长影响的实证分析

以辽宁省大连市农村地区为研究样本,通过构建农村人口结构变化对经济增长影响的"动态效应"模型和"静态效应"模型,分析了农村人口结构变化对农村经济增长的影响.研究结果表明,人力资本是农村经济增长的重要源泉,在既定的农村劳动力从业人口中,男性劳动力人口数量的适度增加能够在一定程度上提高农村经济的增长水平;农村转移劳动力的就业方向对农村经济增长有重要影响;农村储蓄率的增加对于农村经济增长和一系列公共服务的提供具有显著影响效应.     

总人口规模变化和带接种疫苗的年龄结构TB传染病模型的再生数

本文讨论总人口规模变化和带接种疫苗的年龄结构肺结核传染病模型,给出了该模型增值数的显式表达式(R)(ψ,λ)(λ为非病染人口的增长指数),证明了若(R)(ψ,λ)＜1,则无病平衡态是线性稳定的,若(R)(ψ,λ)＞1,则无病平衡态是不稳定的.     

城市区域性人口承载力动态综合测度

对马尔萨斯人口增长模型进行研究,设计人口承载力发展路径和基于增长模型的隶属函数,从概率角度构建人口承载力动态综合测度模型,同时,以城市区域为研究对象,以经济作为人口承载力主导影响因素,辅之以自然、环境、资源与科技因素,构建人口承载力综合评价指标体系,多角度、多因素分析区域人口承载力,寻找人口承载短板,为人口承载力研究提供新的研究方法和视角.实证研究结论显示,研究区域人口承载力当前处于承载力强阶段,并开始向适度阶段过渡,其内部指标和子系统发展不平衡,人口系统自身发展稳定,经济和环境人口承载力强,资源和科技承载力较弱,随着区域经济的发展,在相当长一段时间内可进入适度人口阶段.     

具有内生人口规模的城市经济增长模型

本文研究了城市经济增长与人口规模的相互关系.通过引入含消费与舒适度的双变量效用函数,提出了城市居民效用最大化问题.利用动态优化与动力系统,得出描述模型的二维动力系统,具有唯一双曲型平衡点和优化问题存在唯一最优增长路径.因而,对城市经济增长存在最优的人口规模.     

人口结构变动对中国能源消费碳排放的影响——基于城镇化和居民消费视角

本文通过引入城镇化及居民消费等因素拓展LMDI模型,解构中国能源消费碳排放变动为碳排放因子、能源强度、消费抑制因子、城镇化、居民消费和人口规模六大效应,并探讨上述六种效应变动对中国能源消费碳排放量变动的贡献率及其作用机理。然后,选择中国30个省份,2003-2012年的面板数据实证分析人口结构变动对区域能源消费碳排放量变动及其分解效应的影响。结果表明:2003 2012年中国碳排放总量增加42.1167亿吨,消费抑制因子效应、城镇化效应、居民消费效应和人口规模效应对碳排放量的影响呈现为正效应,而碳排放因子效应和能源强度效应对碳排放量的影响整体上呈现为负效应,并且居民消费效应对碳排放量变动的影响最大。人口城镇化已成为影响中国碳排放量变动的主要人口因素。较之中、西部地区,东部地区的人口规模效应明显较高,但其能源强度效应则相反,中部地区碳排放因子效应明显高于东、西部地区。现阶段,人口年龄结构、人口教育结构和人口职业结构变动减缓了中国碳排放量的增长,而人口城乡结构、区域经济水平和人口规模变动的影响方向则相反,最后,人口性别结构变动对碳排放量变动无显著地影响。     

人口总数变化的急慢性阶段年龄结构传染病模型及稳定性

本文讨论总人口数量变化的具有急性及慢性阶段且都能感染的年龄结构传染病模型,求出了与人口增长指数λ*相关的基本再生数R_0.利用谱理论和齐次动力系统等理论证明,若R_01,则无病平衡点局部渐近稳定;若R_01,则无病平衡点不稳定,这时还有地方病平衡点,并得到地方病平衡点的局部渐近稳定性条件.     

基于灰色理论的人口年龄结构对房地产需求影响分析

通过研究影响房地产市场需求的主要因素,特别引入不同年龄段人口数这一因素,建立了基于灰色理论的房地产市场需求影响因素分析模型,对影响全国房地产市场需求的各因素进行实证分析,从而得出人口年龄结构在影响房地产市场需求中的重要性.并进一步分析人口年龄结构对需求的影响机理.     

Population waves and fertility fluctuations: social security implications.

Based on Canadian data, this study discusses some of the methods which incorporate fertility variations into population forecasts. In particular, the relative shifts in the age structure which can have profound social and economic consequences on the context of a pay as you go national security system are analyzed. In terms of long range economic and social planning, oscillating growth projections are much more difficult to handle and plan for than the constant growth rates predicted by stable population theories. The impact of different types of fertility fluctuations are analyzed in terms of evolution of the dependency ration over time; the dependency ratio corresponds to the ratio of the retired lives of a population to those of the working age population. From the viewpoint of a social security system, the evolution of the dependency ratio over time is of particular importance. Other areas explored are: 1) cohort fertility variations; 2) periodic fertility fluctuations; and 3) limit cycle behaviors. In the context of a national social security plan, one possible response to the population projections would be to maintain the year by year level of the RA ratio (ratio of the population aged 65 and over to the population aged between 20 and 65) at its equilibrium value of 27.6% by adjusting the retirement age appropriately.     

基于变动人口的Solow模型

本文在Solow模型框架中引入随时间变动人口增长函数，并假定人口增长率最终趋于零，证明该模型的解是渐近稳定的，收敛于零人口增长率的经典Solow模型的解。通过引入变动人口增长率，讨论人口过渡时期和人口波动对经济增长的影响，并给出数值计算结果。     

Demographic change in models of endogenous economic growth. A survey

While in exogenous growth models demographic variables are linked to economic prosperity mainly via the population size, the structure of the workforce, and the capital intensity of workers, endogenous growth models and their successors also allow for interrelationships between demographic variables and technological change. However, most of the existing literature considers only the interrelationships based on population size and its growth rate and does not explicitly account for population aging. The aim of this paper is (a) to review the role of population size and population growth in the most commonly used endogenous economic growth models, (b) discuss models that also allow for population aging, and (c) sketch out the policy implications of the most commonly used endogenous growth models and compare them to each other.     

基于Leslie模型的资源持续利用

传统的Leslie模型是具有年龄结构种群演化的有效研究方法.基于持续收获状态的均匀收获是生物资源可持续利用的重要手段.对均匀收获状态下种群保持稳定的条件进行了研究,证明了均匀收获下稳定状态的充要条件,同时基于该条件,给出了临界稳定状态的判定方法,并就临界稳定状态下种群的分布情况进行了研究.通过引入实际数据并就实际数据进行计算,对该判定条件及最终的种群分布情况进行了实证分析.     

On the asymptotic equilibrium of a population system with migration

In the analysis of economic and social issues of a country (or any larger or smaller socio-economic unit) the demographic dynamics of the considered population often play a crucial role. Very current emergencies in this respect are e.g. ageing, longevity risk, state-run healthcare etc. Over the last decade migration between EU countries also became an important issue, and in recent years the uncontrolled migration from non-EU countries is also a major concern. Therefore, the better theoretical understanding of the evolutionary mechanism of age-classified populations interacting via migration, is a timely modelling-methodological task. This paper is a preliminary demographic methodological contribution to a further research in support of socio-economic modelling and decision making concerning migration issues.It is known that in the framework of the classical age-specific Leslie model, under simple demographic conditions, a closed population in the long term tends to an equilibrium age distribution. As the main theoretical result of the paper, a similar convergence is proved for a system of several populations with migration between them, and this long-term behaviour (convergence theorem) is extended to systems of sex-structured populations. Based on the latter model, medium term projections are also analysed concerning the effect of migration among countries on the development of the old-age dependency ratio (the proportion of pensioner age classes to active ones), which is an aggregate scalar indicator of ageing, a major concern in most industrialized countries. Illustrative simulation analysis is carried out with data from three European countries.     

离散状态方程在人口预测问题中的应用

应用地域状态变量建立了人口发展的离散模型.一个重要目的就是评价中国的城市化和人口政策产生的影响.这些问题包括人口数量的预测和关于一些人口指标的讨论,如:人口地域分布、人口年龄分布、性别比、老龄化、抚养率,等.进而讨论了应在何时采取怎样的政策来应对未来的人口困境.     

具有内生人口迁移的经济增长模型

本文考虑两部门的人口迁移过程，假定劳动人口迁移是由于人均资差异引起的，通过引入人口迁移函和反应函数得以一个二维微分方程组，建立起具有人口迁移的经济增长模型，文中证明模型的稳态解是稳定的。文中给出数值计算结果展示经济增长过程的人口迁移过程。     

Proportional economic growth under conditions of limited natural resources

The paper is devoted to economic growth models in which the dynamics of production factors satisfy proportionality conditions. One of the main production factors in the problem of optimizing the productivity of natural resources is the current level of resource consumption, which is characterized by a sharp increase in the prices of resources compared with the price of capital. Investments in production factors play the role of control parameters in the model and are used to maintain proportional economic development. To solve the problem, we propose a two-level optimization structure. At the lower level, proportions are adapted to the changing economic environment according to the optimization mechanism of the production level under fixed cost constraints. At the upper level, the problem of optimal control of investments for an aggregate economic growth model is solved by means of the Pontryagin maximum principle. The application of optimal proportional constructions leads to a system of nonlinear differential equations, whose steady states can be considered as equilibrium states of the economy. We prove that the steady state is not stable, and the system tends to collapse (the production level declines to zero) if the initial point does not coincide with the steady state. We study qualitative properties of the trajectories generated by the proportional development dynamics and indicate the regions of production growth and decay. The parameters of the model are identified by econometric methods on the basis of China’s economic data.     

Stochastic stable population growth

Classical demographic theory purports that the age structure of a population eventually stabilizes. Although the population may continue to grow, once equilibrium is reached, the proportions of people in different age categories do not change. Stochastic analogues can be proven if vital rates fluctuate according to a stationary stochastic process. The action of random matrix products on random vectors is studied. This permits the application of Hilbert's projective metric and leads to considerable simplification of the ergodic and central limit theory of population growth. Appropriate theorems and their proofs are presented.     

Persistence in ecological models of competition for a single resource

We show how the consideration of an intra-specific dependency in the population growth functions can explain a stable persistence of several species in competition for a single resource. This result is applied to a model of single-nutrient competition in the chemostat. To cite this article: C. Lobry et al., C. R. Acad. Sci. Paris, Ser. I 340 (2005).