Population Evolution With Fertility Mode

Penna model is a simulation model of population evolution based on the 0,1 string,and has the population which has age structure as the research subject.In addition to the age structure,the model but also takes into account the environment,genetic variation, reproductive age,population limit and other factors,and uses computer methods to simulate the distribution and evolution of natural populations.The first Charter of this paper briefly introduces asexual Penna model and sexual Penna model.In both modes,we set specific parameters to discuss the development trend of population size and the changes.Simulation come:After a certain period of time,the population will tend to steady state to dynamic balance and draw the complex and compelling result,which shows the rationality of the Penna model in reality.Based on the above-mentioned sexual Penna model,the second chart of this article adds the concept of family,establish the family Penna model to make the population reproduces offspring in the family form,and discusses the development and changes of population size and age ratio in this mode.As a result of the family form is we human reproductive way, applying it to the issue of China's population can provide methods for China to research Population development.Based on the above-mentioned family Penna model,the third chart simulates the impact different fertility policy that is the maximum number of children in a family on population size,average age and age ratio.Through simulation we come:the fewer the maximum number of children in a family,the smaller the balance of the population size,the smaller the younger ratio,the bigger the older ratio,the more serious the aging problem.As China's integration with the world,DINK family is understood and accepted by society and the public,DINK phenomenon in our country is increasingly becoming a common phenomenon.So the fourth chart of this article adds DINK family to the Penna model to research the impact the DINK family ratio on population size and age ratio.We come:with the DINK family ratio becomes bigger,the population size reduces and the aging problem becomes serious.The emergence of DINK family will have a significant impact on the development of China's population and age structure.The fifth chart simulates the combined effects DINK family and fertility policy on population,it illustrates that the adjusting time under their combined effects is different with the adjusting time when we do not consider DINK phenomenon.Applying this model to the issue of China's population,the overall results show that in order to ensure the quantity and quality of our country's population,we must adjust fertility policies timely,and it is necessary to fully consider the DINK phenomenon for the determination of the adjusting time.The whole article is based on the Penna model,adds family concept and DINK family, discusses the effects the fertility policy and DINK family ratio on population size and age structure,finally we come more satisfactory and convincing conclusions.Because this model is similar to the human development model,we apply it to the development of China's population issues.Conclusions have an important and reliable reference value for our country to make the fertility policy that is adapt to the development of our country to both effectively control the scale of China's population and prevent the serious problems of the aging.