The flexible materials exhibit more favorable properties than most rigid substrates in flexibility,weight saving,mechanical reliability,and excellent environmental toughness.Particularly,flexible graphene film with un...The flexible materials exhibit more favorable properties than most rigid substrates in flexibility,weight saving,mechanical reliability,and excellent environmental toughness.Particularly,flexible graphene film with unique mechanical properties was extensively explored in high frequency devices.Herein,we report the characteristics of structure and magnetic properties at high frequency of Co2FeAl thin film with different thicknesses grown on flexible graphene substrate at room temperature.The exciting finding for the columnar structure of Co2FeAl thin film lays the foundation for excellent high frequency property of Co2FeAl/flexible graphene structure.In-plane magnetic anisotropy field varying with increasing thickness of Co2FeAl thin film can be obtained by measurement of ferromagnetic resonance,which can be ascribed to the enhancement of crystallinity and the increase of grain size.Meanwhile,the resonance frequency which can be achieved by the measurement of vector network analyzer with the microstrip method increases with increasing thickness of Co2FeAl thin film.Moreover,in our case with graphene film,the resonance magnetic field is quite stable though folded for twenty cycles,which demonstrates that good flexibility of graphene film and the stability of high frequency magnetic property of Co2FeAl thin film grown on flexible graphene substrate.These results are promising for the design of microwave devices and wireless communication equipment.展开更多
For the first time, we report on projective synchronization between two time delay chaotic systems with single time delays. It overcomes some limitations of the previous work, where projective synchronization has been...For the first time, we report on projective synchronization between two time delay chaotic systems with single time delays. It overcomes some limitations of the previous work, where projective synchronization has been investigated only in finite-dimensional chaotic systems, so we can achieve projective synchronization in infinitedimensional chaotic systems. We give a general method with which we can achieve projective synchronization in time-delayed chaotic systems. The method is illustrated using the famous delay-differential equations related to optical bistability. Numerical simulations fully support the analytical approach.展开更多
Projective synchronization in modulated time-delayed systems is studied by applying an active control method.Based on the Lyapunov asymptotical stability theorem,the controller and sufficient condition for projective ...Projective synchronization in modulated time-delayed systems is studied by applying an active control method.Based on the Lyapunov asymptotical stability theorem,the controller and sufficient condition for projective synchronization are calculated analytically.We give a general method with which we can achieve projective synchronization in modulated time-delayed chaotic systems.This method allows us to adjust the desired scaling factor arbitrarily.The effectiveness of our method is confirmed by using the famous delay-differential equations related to optical bistable or hybrid optical bistable devices.Numerical simulations fully support the analytical approach.展开更多
The collective synchronization of a system of coupled logistic maps on random community networks is investigated. It is found that the synchronizability of the community network is affected by two factors when the siz...The collective synchronization of a system of coupled logistic maps on random community networks is investigated. It is found that the synchronizability of the community network is affected by two factors when the size of the network and the number of connections are fixed. One is the number of communities denoted by the parameter rn, and the other is the ratio σ of the connection probability p of each pair of nodes within each community to the connection probability q of each pair of nodes among different communities. Theoretical analysis and numerical results indicate that larger rn and smaller σ are the key to the enhancement of network synchronizability. We also testify synchronous properties of the system by analysing the largest Lyapunov exponents of the system.展开更多
We have investigated the influence of the average degree （k） of network on the location of an order-disorder transition in opinion dynamics. For this purpose, a variant of majority rule （VMR） model is applied to W...We have investigated the influence of the average degree （k） of network on the location of an order-disorder transition in opinion dynamics. For this purpose, a variant of majority rule （VMR） model is applied to Watts-Strogatz （WS） small-world networks and Barabasi-Albert （BA） scale-free networks which may describe some non-trivial properties of social systems. Using Monte Carlo simulations, we find that the order-disorder transition point of the VMR model is greatly affected by the average degree （k） of the networks; a larger value of （k） results in a more ordered state of the system. Comparing WS networks with BA networks, we find WS networks have better orderliness than BA networks when the average degree （k） is small. With the increase of （k）, BA networks have a more ordered state. By implementing finite-size scaling analysis, we also obtain critical exponents β/v, γ/u and 1/v for several values of average degree （k）. Our results may be helpful to understand structural effects on order-disorder phase transition in the context of the majority rule model.展开更多
We investigate different types of synchronization between two unidirectionally nonlinearly coupled identical delay- differential systems related to optical bistable or hybrid optical bistable devices. This system can ...We investigate different types of synchronization between two unidirectionally nonlinearly coupled identical delay- differential systems related to optical bistable or hybrid optical bistable devices. This system can represent some kinds of delay-differential models, i.e. Ikeda model, Vall^e model, sine-square model, Mackey Glass model, and so on. We find existence and sufficient stability conditions by theoretical analysis and test the correctness by＂ numerical simulations. Lag, complete and anticipating synchronization are observed, respectively. It is found that the time-delay system can be divided into two parts~ one is the instant term and the other is the delay term. Synchronization between two identical chaotic systems can be derived by adding a coupled term to the delay term in the driven system.展开更多
The in-plane effective 90°magnetization rotation of Co_(2) FeAl thin film grown on PMN-PT substrate induced by the electric field is investigated at room temperature.The magnetic hysteresis loops under different ...The in-plane effective 90°magnetization rotation of Co_(2) FeAl thin film grown on PMN-PT substrate induced by the electric field is investigated at room temperature.The magnetic hysteresis loops under different positive and negative electric fields are obtained,which reveals remanent magnetization can be mediated by the electric field.Moreover,under positive electric fields,the obvious 90°magnetization rotation can be observed,while remanent magnetization is nearly unchanged under negative electric fields.The result is consistent with the electric field dependence of effective magnetic field,which can be attributed to the piezostrain effect in Co_(2) FeAl/PMN-PT structure.In addition,the piezostrain-mediated 90°magnetization rotation can be demonstrated by the result of resonance field changing with electric field in the measurement of ferromagnetic resonance,which is promising for the design of future multiferroic devices.展开更多
In this paper,we propose a method for the projective synchronization between two different chaotic systems with variable time delays.Using active control approach,the suitable controller is constructed to make the sta...In this paper,we propose a method for the projective synchronization between two different chaotic systems with variable time delays.Using active control approach,the suitable controller is constructed to make the states of two different diverse time delayed systems asymptotically synchronize up to the desired scaling factor.Based on the Lyapunov stability theory,the sufficient condition for the projective synchronization is calculated theoretically.Numerical simulations of the projective synchronization between Mackey-Glass system and Ikeda system with variable time delays are shown to validate the effectiveness of the proposed algorithm.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51901163 and 12104171)the Fundamental Research Funds for the Central Universities(Grant No.2021XXJS025).
文摘The flexible materials exhibit more favorable properties than most rigid substrates in flexibility,weight saving,mechanical reliability,and excellent environmental toughness.Particularly,flexible graphene film with unique mechanical properties was extensively explored in high frequency devices.Herein,we report the characteristics of structure and magnetic properties at high frequency of Co2FeAl thin film with different thicknesses grown on flexible graphene substrate at room temperature.The exciting finding for the columnar structure of Co2FeAl thin film lays the foundation for excellent high frequency property of Co2FeAl/flexible graphene structure.In-plane magnetic anisotropy field varying with increasing thickness of Co2FeAl thin film can be obtained by measurement of ferromagnetic resonance,which can be ascribed to the enhancement of crystallinity and the increase of grain size.Meanwhile,the resonance frequency which can be achieved by the measurement of vector network analyzer with the microstrip method increases with increasing thickness of Co2FeAl thin film.Moreover,in our case with graphene film,the resonance magnetic field is quite stable though folded for twenty cycles,which demonstrates that good flexibility of graphene film and the stability of high frequency magnetic property of Co2FeAl thin film grown on flexible graphene substrate.These results are promising for the design of microwave devices and wireless communication equipment.
基金Supported by Research Project of Hubei Provincial Department of Education under Grant No.Q20101609Foundation of Wuhan Textile University under Grant No.105040
文摘For the first time, we report on projective synchronization between two time delay chaotic systems with single time delays. It overcomes some limitations of the previous work, where projective synchronization has been investigated only in finite-dimensional chaotic systems, so we can achieve projective synchronization in infinitedimensional chaotic systems. We give a general method with which we can achieve projective synchronization in time-delayed chaotic systems. The method is illustrated using the famous delay-differential equations related to optical bistability. Numerical simulations fully support the analytical approach.
基金Supported by the Research Project of Hubei Provincial Department of Education under No Q20101609the Foundation of Wuhan Textile University under No 105040.
文摘Projective synchronization in modulated time-delayed systems is studied by applying an active control method.Based on the Lyapunov asymptotical stability theorem,the controller and sufficient condition for projective synchronization are calculated analytically.We give a general method with which we can achieve projective synchronization in modulated time-delayed chaotic systems.This method allows us to adjust the desired scaling factor arbitrarily.The effectiveness of our method is confirmed by using the famous delay-differential equations related to optical bistable or hybrid optical bistable devices.Numerical simulations fully support the analytical approach.
基金Project supported by the National Natural Science Foundation of China (Grant No 10775060)
文摘The collective synchronization of a system of coupled logistic maps on random community networks is investigated. It is found that the synchronizability of the community network is affected by two factors when the size of the network and the number of connections are fixed. One is the number of communities denoted by the parameter rn, and the other is the ratio σ of the connection probability p of each pair of nodes within each community to the connection probability q of each pair of nodes among different communities. Theoretical analysis and numerical results indicate that larger rn and smaller σ are the key to the enhancement of network synchronizability. We also testify synchronous properties of the system by analysing the largest Lyapunov exponents of the system.
基金Project supported by the National Natural Science Foundation of China (Grant No.10775060)
文摘We have investigated the influence of the average degree （k） of network on the location of an order-disorder transition in opinion dynamics. For this purpose, a variant of majority rule （VMR） model is applied to Watts-Strogatz （WS） small-world networks and Barabasi-Albert （BA） scale-free networks which may describe some non-trivial properties of social systems. Using Monte Carlo simulations, we find that the order-disorder transition point of the VMR model is greatly affected by the average degree （k） of the networks; a larger value of （k） results in a more ordered state of the system. Comparing WS networks with BA networks, we find WS networks have better orderliness than BA networks when the average degree （k） is small. With the increase of （k）, BA networks have a more ordered state. By implementing finite-size scaling analysis, we also obtain critical exponents β/v, γ/u and 1/v for several values of average degree （k）. Our results may be helpful to understand structural effects on order-disorder phase transition in the context of the majority rule model.
文摘We investigate different types of synchronization between two unidirectionally nonlinearly coupled identical delay- differential systems related to optical bistable or hybrid optical bistable devices. This system can represent some kinds of delay-differential models, i.e. Ikeda model, Vall^e model, sine-square model, Mackey Glass model, and so on. We find existence and sufficient stability conditions by theoretical analysis and test the correctness by＂ numerical simulations. Lag, complete and anticipating synchronization are observed, respectively. It is found that the time-delay system can be divided into two parts~ one is the instant term and the other is the delay term. Synchronization between two identical chaotic systems can be derived by adding a coupled term to the delay term in the driven system.
基金the National Natural Science Foundation of China(Grant Nos.51901163 and 61903280)the Foundation of Wuhan Textile University(Grant Nos.193128 and 205033).
文摘The in-plane effective 90°magnetization rotation of Co_(2) FeAl thin film grown on PMN-PT substrate induced by the electric field is investigated at room temperature.The magnetic hysteresis loops under different positive and negative electric fields are obtained,which reveals remanent magnetization can be mediated by the electric field.Moreover,under positive electric fields,the obvious 90°magnetization rotation can be observed,while remanent magnetization is nearly unchanged under negative electric fields.The result is consistent with the electric field dependence of effective magnetic field,which can be attributed to the piezostrain effect in Co_(2) FeAl/PMN-PT structure.In addition,the piezostrain-mediated 90°magnetization rotation can be demonstrated by the result of resonance field changing with electric field in the measurement of ferromagnetic resonance,which is promising for the design of future multiferroic devices.
基金Supported by Research Project of Hubei Provincial Department of Education under Grant No. Q20101609Foundation of Wuhan Textile University under Grant No. 105040
文摘In this paper,we propose a method for the projective synchronization between two different chaotic systems with variable time delays.Using active control approach,the suitable controller is constructed to make the states of two different diverse time delayed systems asymptotically synchronize up to the desired scaling factor.Based on the Lyapunov stability theory,the sufficient condition for the projective synchronization is calculated theoretically.Numerical simulations of the projective synchronization between Mackey-Glass system and Ikeda system with variable time delays are shown to validate the effectiveness of the proposed algorithm.
