Study on the dependence of the two-dimensional Ikeda model on the parameter

Based on the property of solutions of the nonlinear differential equation,this paper focuses on the behavior of solutions to the two-dimensional Ikeda model,especially the dependence of the solutions on the parameter.The dependency relationship of the two-dimensional Ikeda model on the parameter is revealed by a large sample of proper numerical simulations.With the parameter varying from 0 to 1,the numerical solutions change from a point attractor to periodic solutions,then to chaos,and end up with a limit cycle.Furthermore,the route from bifurcation to chaos is shown to be continuous period-doubling bifurcations.The nonlinear structures presented by the solution of the two-dimensional Ikeda model indicate that,by setting different model parameters,one can test a new method that will be adopted to study atmospheric or oceanic predictability and/or stability.The corresponding test results provide some useful information on the ability of the new approach overcoming the impacts of strong nonlinearity.

清代直隶口外地区乡村聚落空间格局演变及主控因子分析--以青龙县为例

直隶口外地区是清代乡村聚落变化最激烈的地区之一,经历了从无到有再到兴盛的过程,村落的形成与发展标志着直隶口外地区由游牧社会向农耕社会的巨大转变。在县志和地名志等资料的基础上,运用GIS空间分析法和二元Logistic回归模型分析清代青龙县乡村聚落空间格局演变过程和演化的驱动力。其演化过程主要经历了骤然增长的“双轴”时期、快速增长的“双轴+多核”时期和缓慢增长的相对均衡时期三个阶段。回归模型结果表明乡村聚落分布呈现出低海拔、低坡度、近河流、远冷口、远主道路的指向,人口和海拔是影响乡村聚落空间格局演变的主控因子。