人口线性系统模型探讨

本文提出人口系统发展方程的一种改进形式。它使人口系统模型与一般线性系统模型具有等价的公式表达,并使人口控制理论与现代系统控制理论联系起来。本文提出的方法在应用上具有更简单、直观的形式,它可以作为人口预测与人口最优控制的一种计算方法。     

人口问题与人工社会方法:人工人口系统的设想与应用

提出利用人工社会的思想，结合复杂系统的理论和方法，建立人工人口系统以及相应的人口计算试验手段和人口管理平行系统的设想。主要工作包括人工人口系统的基本框架，计算试验与人口政策的评估、平行系统与人口的控制与管理，以及基本综合集成研讨厅的实现方式。     

MODELLING AND STABILITY ANALYSIS OF POPULATION GROWTH WITH SPATIAL DIFFUSION

In recent years, population growth models with spatial diffusion have beenextensively studied by many authors (for example, see [1-5]). In this paper, a populationgrowth model is considered with a discrete age-dependence and spatial diffusion, and isinvestigated in a semigroup framework. The spectral properties of the population oper-ator are given. On the basis of such spectral consideration, the asymptotic behaviourof the semigroup generated by the population operator is obtained. Finally, a nonlinearpopulation growth model is considered and its stability is analyzed.     

Research of Population Development in Qingchuan County

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基于STIRPAT模型的环境压力影响因素及其演进分析——以湖南省为例

基于STIRPAT扩展模型,利用岭回归分析法对1985～2007年湖南相关数据进行分析,探讨人口数量等因素对环境压力的影响以及演进,研究结果表明:人口增长、城市化和人均消费水平提高导致环境压力增大,而技术水平对环境的作用相反;在不同阶段,各因素对环境压力的影响不同,人口数量的影响程度逐步降低,而人均消费和人口城市化逐步取代人口数量成为最重要和第二重要的影响因素。针对各因素对环境压力的影响,本文提出了相关政策建议。     

The Impact of Population Aging on Housing Demand in China Based on System Dynamics

In recent years, the proportion of China's elderly population is gradually increasing, and the real estate market is changing dramatically. Consequently the impact of population aging on housing demand has become increasingly prominent. On the theoretical basis of the relationship between population aging, family structure and housing demand, this paper firstly constructs a system dynamics model of the impact of population aging and family structure on housing demand in China. Then,the model is simulated, and several scenarios of population, family structure, and real estate policies are set up. The main conclusions of this paper are as follows: China's population will rise at first and then decrease, reaching a peak of 1.401 billion by 2023. As the proportion of elderly population increases, the degree of population aging is becoming increasingly serious. The size of the family will gradually shrink to 2.39 people per household in 2050. The housing demand will increase first and then decrease. Through the results of scenario simulation, this paper puts forward the following suggestion to effectively balance the housing demand in China: Completely relaxing family planning policies,imposing a real estate tax, canceling the pre-sale policy, and raising the loan rate.     

基于灰色GM(1,1)模型的上海城镇养老保险人口分布预测

通过利用上海人口普查和1%人口抽样调查数据及历年统计年鉴数据,结合人口精算学递推和灰色动态GM(1,1)模型,对2008-2050年上海城镇养老保险"老人、中人、新人"在职和退休人口分布数据做出分类预测.在对人口预测结果曲线趋势分析基础上发现上海基本养老保险系统实现可持续发展中潜在的最大危机——退休人口抚养危机.研究结论对于上海市养老保险基金收支缺口测算及新人口政策制定具有重要的理论意义和应用价值.     

一种基于种群竞争与交流模型的多群进化规划算法

进化不仅是一个环境通过自然选择对物种施加影响的过程，同时也是种群间相互竞争和交流的结果。基于此种考虑，提出了一种基于种群竞争与交流模型的多群进化规划算法。在该算法中，种群的规模取决于种群间的竞争，种群的变异压力来自其生存空间。种群间的信息交换通过种群的个体交流实现，而种群间个体的交流则来自种群规模的变化。对典型算例的数值仿真表明，该算法能够改善传统的进化规划算法易早熟收敛的弱点，同时具有良好的快速收敛性和参数鲁棒性。     

基于信息熵对遗传算法中杂交概率的研究

针对现有杂交概率的计算方法复杂且不利于种群摆脱局部优现象,提出了基于信息熵的杂交概率计算方法。利用种群熵和种群方差来分析杂交算子在种群进化中的作用,充分考虑了种群的整体情况和进化潜力,从而确定杂交概率的计算,以更好地控制遗传算法的进化过程。数值实验表明,新提出的杂交概率计算方式不仅便于求解,而且能有效地增强算法的稳定性、全局收敛性,加快算法收敛速度,使算法易于摆脱局部优现象。     

传染病传播模型综述

建立传染病传播模型是理解传染病流行机理, 预测流行趋势, 进行防控决策的基础. 将传染病传播模型分为单一群体模型, 复合群体模型和微观个体模型三类. 单一群体模型从宏观角度刻画了集计量的变化, 以经典的\,SIR\,为基础, 在仓室设置、 年龄结构、 随机性、 异质性等方面进行了扩展. 复合群体模型将人群划分为多个子群体, 子群体之间因人口流动而耦合, 适合研究具有空间异质性的跨地区传播问题. 微观个体模型的出发点是个体状态和行为, 所有个体形成接触网络. 这类模型有理想网络和现实网络两个研究方向, 理想网络关注接触网络特性对传染病传播动力学的影响, 现实网络致力于揭示社会接触的实际特征, 构建足够真实的模拟网络, 研究传染病的传播. 这三类模型各有特点, 分别具有各自的适用领域, 应根据研究目的和问题特点选择合适的建模方法.     

阶梯型粒子群算法及在函数优化中的应用

提出一种自适应动态群粒子群方法,根据粒子群的多样性,采用梯形规律动态调整粒子群的规模,既保证每个粒子都得到充分的进化,又保持了群体的多样性,使局部收敛的可能性大大减少。此方法根据群体的多样性的大小,在减少群体规模时,采用较差淘汰法,淘汰一些较差的粒子,在增加粒子时,采用交叉法产生新个体,既保持粒子的继承性,又维持了粒子群的多样性。对典型函数进行测试实验,结果与其它粒子群方法进行比较,验证了方法的有效性。     

面向多峰函数的自适应小生境量子进化算法

为解决量子进化算法在多峰优化时只能找到一个最优解,无法找到所有全局和局部最优解的问题,提出自适应小生境量子进化算法。利用佳点集理论初始化种群,使种群均匀分布在整个搜索空间;提出中心地形信息小生境自适应识别方法,用于自适应的识别峰值所在区域,并建立小生境完善策略,提高小生境识别速度;借助量子进化算法的快速寻优能力精确寻找各个峰值点;采用动态种群调整策略,维持种群的多样性,自适应地调节种群规模。仿真实验结果表明,该算法具有较强全局优化能力和局部优化能力,且搜索到的每个最优解都达到了理想值。     

STUDY ON HARVESTED POPULATION WITH DIFFUSIONAL MIGRATION

1 IntroductionBiological resources are renewable resources. Ih the eXPlOitation of population resources)both the economic benefits and the environmelltal effects must be taken icao accoullt. Theharvesting problexns on the pOPulation have been studied otensively in the literature [1--3]. Inpractical management, because of wrong exPloitation, some resouxces population are exploitedtoo heavily, and in the 6Xtreme case, are driven to 6Xtinction.In order to prevent the resources population from…     

An algorithm for determination of age-specific fertility rate from initial age structure and total population

Age-specific fertility rate and total fertility rate of females are the most important parameters in population dynamics.This paper proposes an algorithm to get these parameters from the initial age distribution and the total population the years followed.The idea is natural in the sense that the total population is easily to be obtained in a closed society.The authors use a discrete population model to formulate this problem into an inverse problem,which is ill-posed generally.A necessary and sufficient condition for the identifiability is established.An algorithm for reconstruction of age-specific fertility rate is developed.     

The UK population: how does it compare?

This is the fourth demographic report for the UK, providing an overview of the latest statistics on the population. This year's article compares the UK with other European countries and a range of nations from around the world. Statistical comparisons are made for fertility, mortality, ageing, migration and population density. The UK has an ageing population, but one that is not ageing as rapidly as some other countries such as Germany, Italy and Japan. Although life expectation in the UK is improving in line with most western European countries, relatively high levels of fertility ensure that the proportion of the population that is young remains high. Around one in ten residents of the UK are foreign born, a lower proportion than many developed countries. UK population density has increased steadily and is the fourth highest in the EU.     

自适应动态控制种群分组的自然计算方法

多种群优化方法可以解决数据量增大导致的优化难度增加的问题,现有的种群分组都采用随机分组或人为设定的方法,没有充分考虑粒子运动轨迹。针对此问题,提出一种种群分组自适应动态控制策略,使用高斯拟合函数作为种群分组的参考曲线,根据函数单调区间划分子种群;对于有越过子种群上界趋势的粒子采用逆向策略,保持种群多样性同时提高收敛速度。该策略不依赖于算法的具体进化过程,适用于所有基于种群优化的自然计算方法。验证实验结果表明了所提新算法的有效性和普适性。     

The demographic situation in the European Union

This article is an update of a similar article published in Population Trends 104 and complements the article on European-wide issues in population statistics, published in Population Trends 118. The main areas of demography are covered, namely population change, population composition, fertility and mortality. Eurostat are currently working on a new set of population projections which should be available shortly, but were not completed when this article was drafted.     

The changing demographic picture of the UK: national statistician's annual article on the population

The population of the UK is currently growing at its fastest rate since the 1960s, increasing by two and a half per cent between mid-2001 and mid-2006. While life expectancy continues to increase, fertility rates have also been increasing in the last five years and are currently at their highest level since 1980. In addition, international migration has led to the UK population growing by an average of 500 people per day over the last five years. The population is also becoming increasingly diverse and mobile, and these factors make it increasingly challenging to measure population change accurately. This is the first of a series of annual reports on the population of the UK; these reports will provide an overview of the latest statistics on the population and will also focus on one specific topic - for this report the topic is fertility and, in particular, the impact of migration on fertility, but different topics will be covered in future years. The reports will also highlight the key strands of work being taken forward within the National Statistics Centre for Demography in order to improve UK population statistics. More detailed information on the populations of Wales, Scotland and Northern Ireland are available in the annual demographic reports produced by the respective devolved administrations.'     

An international comparative study on the use of the Cohort Component Method for estimating national populations

This comparative study explores the use of the Cohort Component Method (CCM) to produce national level population estimates. This method is used annually to calculate mid-year population estimates for England and Wales by the Office for National Statistics (ONS). Initially the article considers recent population change in England and Wales, with particular emphasis on the growing importance and challenges faced by migration estimation. Comparisons are then made between how population estimates are produced in England and Wales and other countries, with a particular focus on differences in the way the CCM is applied. Recent changes in methods used to estimate population are then reviewed along with a discussion of alternative approaches such as those described in academic literature.