Understanding the cause of the synchronization of population evolution is an important issue for ecologicalimprovement.Here we present a Lotka-Volterra-type model driven by two correlated environmental noises and show...Understanding the cause of the synchronization of population evolution is an important issue for ecologicalimprovement.Here we present a Lotka-Volterra-type model driven by two correlated environmental noises and show,via theoretical analysis and direct simulation,that noise correlation can induce a synchronization of the mutualists.Thetime series of mutual species exhibit a chaotic-like fluctuation,which is independent of the noise correlation,however,the chaotic fluctuation of mutual species ratio decreases with the noise correlation.A quantitative parameter defined forcharacterizing chaotic fluctuation provides a good approach to measure when the complete synchronization happens.展开更多
By considering a magnetic system of an ensemble of nanometer clusters without any external magnetic field,the Monte Carlo simulation of the Heisenberg model is used to investigate the transition from a superparamagnet...By considering a magnetic system of an ensemble of nanometer clusters without any external magnetic field,the Monte Carlo simulation of the Heisenberg model is used to investigate the transition from a superparamagnetism to a ferromagnetic single-domain state,which is caused by the growth of the clusters.We studied the variation of the dynamic growth exponent P and the transition critical size of the cluster N_(c) against the reduced temperature t and the uniaxial anisotropy constant A.Ws found that the growth exponent maximized at a certain temperature,other than being taken as a universal constant as some researchers suggested previously.展开更多
基金National Natural Science Foundation of China under Grant No.60471023
文摘Understanding the cause of the synchronization of population evolution is an important issue for ecologicalimprovement.Here we present a Lotka-Volterra-type model driven by two correlated environmental noises and show,via theoretical analysis and direct simulation,that noise correlation can induce a synchronization of the mutualists.Thetime series of mutual species exhibit a chaotic-like fluctuation,which is independent of the noise correlation,however,the chaotic fluctuation of mutual species ratio decreases with the noise correlation.A quantitative parameter defined forcharacterizing chaotic fluctuation provides a good approach to measure when the complete synchronization happens.
基金Supported by the National Natural Science Foundation of China under the Grant No.59702004.
文摘By considering a magnetic system of an ensemble of nanometer clusters without any external magnetic field,the Monte Carlo simulation of the Heisenberg model is used to investigate the transition from a superparamagnetism to a ferromagnetic single-domain state,which is caused by the growth of the clusters.We studied the variation of the dynamic growth exponent P and the transition critical size of the cluster N_(c) against the reduced temperature t and the uniaxial anisotropy constant A.Ws found that the growth exponent maximized at a certain temperature,other than being taken as a universal constant as some researchers suggested previously.
