Chaotic dynamics of the van der Pol-Duffing oscillator subjected to periodic external and parametric excitations with delayed feedbacks are investigated both analytically and numerically in this manuscript.With the Me...Chaotic dynamics of the van der Pol-Duffing oscillator subjected to periodic external and parametric excitations with delayed feedbacks are investigated both analytically and numerically in this manuscript.With the Melnikov method,the critical value of chaos arising from homoclinic or heteroclinic intersections is derived analytically.The feature of the critical curves separating chaotic and non-chaotic regions on the excitation frequency and the time delay is investigated analytically in detail.The monotonicity of the critical value to the excitation frequency and time delay is obtained rigorously.It is presented that there may exist a special frequency for this system.With this frequency,chaos in the sense of Melnikov may not occur for any excitation amplitudes.There also exists a uncontrollable time delay with which chaos always occurs for this system.Numerical simulations are carried out to verify the chaos threshold obtained by the analytical method.展开更多
In this paper,we propose a backstepping approach for the synchronization and control of modified Van-der Pol Duffing oscillator circuits.The method is such that one controller function that depends essentially on avai...In this paper,we propose a backstepping approach for the synchronization and control of modified Van-der Pol Duffing oscillator circuits.The method is such that one controller function that depends essentially on available circuit parameters that is sufficient to drive the two coupled circuits to a synchronized state as well achieve the global stabilization of the system to its regular dynamics.Numerical simulations are given to demonstrate the effectiveness of the technique.展开更多
The principal resonance of Van der Pol-Duffing oscillator to combined deterministic and random parametric excitations is investigated. The method of multiple scales was used to determine the equations of modulation of...The principal resonance of Van der Pol-Duffing oscillator to combined deterministic and random parametric excitations is investigated. The method of multiple scales was used to determine the equations of modulation of amplitude and phase. The behavior, stability and bifurcation of steady state response were studied. Jumps were shown to occur under some conditions. The effects of damping, detuning, bandwidth, and magnitudes of deterministic and random excitations are analyzed. The theoretical analysis were verified by numerical results.展开更多
研究了 Van der Pol-Duffing振子在简谐与随机噪声联合激励下的响应问题。用参数变换法使方程出现小参数 ,用多尺度法分离系统的快变项 ,讨论系统的阻尼项、非线性项和随机项等参数对系统响应的影响。理论分析和数值模拟表明 ,当随机激...研究了 Van der Pol-Duffing振子在简谐与随机噪声联合激励下的响应问题。用参数变换法使方程出现小参数 ,用多尺度法分离系统的快变项 ,讨论系统的阻尼项、非线性项和随机项等参数对系统响应的影响。理论分析和数值模拟表明 ,当随机激励强度增大时 ,系统的响应可从一个极限环变为一个扩散的极限环 ;在一定的条件下 ,系统可有两个稳定的稳态解及随机跳跃现象。展开更多
研究了Van der Pol-Duffing振子的混沌动力学行为,应用直接微扰法构造了系统的通解,由该通解获得了预测混沌出现的Melnikov判据.在非微扰情形,相图和相应Poincaré截面的演化结果表明:系统阻尼和外驱动力的变化都可以导致系统由倍...研究了Van der Pol-Duffing振子的混沌动力学行为,应用直接微扰法构造了系统的通解,由该通解获得了预测混沌出现的Melnikov判据.在非微扰情形,相图和相应Poincaré截面的演化结果表明:系统阻尼和外驱动力的变化都可以导致系统由倍周期分叉进入混沌状态,当频率参数取相同值时,系统混沌被完全抑制.展开更多
研究了改进型Van der Pol-Duffing混沌振子的同步问题。当驱动系统的参数已知时,根据Lyapunov稳定性理论,设计了一个线性反馈控制器,使两个相同的改进型Van der Pol-Duffing混沌振子同步,并得出了保守性较小的同步条件;当驱动系统的参...研究了改进型Van der Pol-Duffing混沌振子的同步问题。当驱动系统的参数已知时,根据Lyapunov稳定性理论,设计了一个线性反馈控制器,使两个相同的改进型Van der Pol-Duffing混沌振子同步,并得出了保守性较小的同步条件;当驱动系统的参数未知时,利用自适应控制方法,选择了适当的自适应律,构造了两个简单的控制器,使响应系统与驱动系统同步,并同时实现了驱动系统中未知参数的辨识。通过数值仿真,表明了这些方法的有效性。展开更多
用平均法研究了含分数阶导数项的van der Pol-Duffing振子的动力学行为和力传递率。得到了主共振时振子的一阶解析解、定常解幅频曲线和相频曲线的解析表达式,进一步通过与数值解作对比,验证了解析解的正确性,分析了不同参数对幅频曲线...用平均法研究了含分数阶导数项的van der Pol-Duffing振子的动力学行为和力传递率。得到了主共振时振子的一阶解析解、定常解幅频曲线和相频曲线的解析表达式,进一步通过与数值解作对比,验证了解析解的正确性,分析了不同参数对幅频曲线和力传递率的影响。结果表明:解析解与数值解吻合良好;在无量纲情况下,共振区分数阶项系数、非线性参数、分数阶阶次、阻尼比对幅频曲线和力传递率的共振峰值均有抑制作用;不同频率区段参数对隔振效果的影响不同,在低频隔振区非线性参数和幅值越小隔振效果越好,此外阻尼比对力传递率影响很小;在高频隔振区增大非线性参数、幅值和阻尼比有助于提高隔振效果。展开更多
In this paper, a modified averaging scheme is presented for a class of time-delayed vibration systems with slow variables. The new scheme is a combination of the averaging techniques proposed by Hale and by Lehman and...In this paper, a modified averaging scheme is presented for a class of time-delayed vibration systems with slow variables. The new scheme is a combination of the averaging techniques proposed by Hale and by Lehman and Weibel, respectively. The averaged equation obtained from the modified scheme is simple enough but it retains the required information for the local nonlinear dynamics around an equilibrium. As an application of the present method, the delay value for which a secondary Hopf bifurcation occurs is successfully located for a delayed van der Pol oscillator.展开更多
传统方法检测微弱信号具有一定的困难,利用混沌振子对微弱信号敏感以及对强噪声具有良好免疫力的特性,提出基于耦合Van der Pol-Duffing振子系统检测微弱信号的新方法。对比不同参数下耦合系统的动力学行为,通过分岔图和二分法确定临界...传统方法检测微弱信号具有一定的困难,利用混沌振子对微弱信号敏感以及对强噪声具有良好免疫力的特性,提出基于耦合Van der Pol-Duffing振子系统检测微弱信号的新方法。对比不同参数下耦合系统的动力学行为,通过分岔图和二分法确定临界阈值,保证阈值搜索速度和阈值精度。阐述基于相图的微弱信号检测原理,通过从混沌态到周期态的转变成功检测淹没在强噪声中的微弱信号,信噪比门限达到–30 d B。同时考察不同精度幅值下噪声对系统状态的影响,不同频率信号以及相移对检测的影响。仿真结果表明,该耦合系统在强噪声条件下对微弱信号敏感,用于检测微弱信号是可行的。展开更多
研究含时滞的大规模van der Pol-Duffing耦合振子系统的非线性动力学.通过讨论特征方程根分布情况确定系统的稳定性,并在耦合时滞和强度平面上给出振幅死亡区域.结合数值算例,揭示同步和异步周期振荡、概周期运动以及混沌吸引子等现象....研究含时滞的大规模van der Pol-Duffing耦合振子系统的非线性动力学.通过讨论特征方程根分布情况确定系统的稳定性,并在耦合时滞和强度平面上给出振幅死亡区域.结合数值算例,揭示同步和异步周期振荡、概周期运动以及混沌吸引子等现象.基于非线性振子电路和时滞电路,构建电路实验平台,有效验证理论和数值结果.研究结果表明,时滞可以显著影响系统动力学特性,如诱发振幅死亡、稳定性切换以及复杂振荡等.展开更多
研究了同时含有平方项和高次幂项的Van der Pol-Duffing系统的混沌行为及混沌控制问题,数值仿真分析了该系统存在的典型非线性动力学行为.主要采用单初始点分岔分析方法、最大Lyapunov指数和Poincare映射方法,从不同侧面揭示了在周期激...研究了同时含有平方项和高次幂项的Van der Pol-Duffing系统的混沌行为及混沌控制问题,数值仿真分析了该系统存在的典型非线性动力学行为.主要采用单初始点分岔分析方法、最大Lyapunov指数和Poincare映射方法,从不同侧面揭示了在周期激振力作用下系统的周期运动、混沌运动,以及运动形式的演化过程,并用x|x|控制方法实现了系统的混沌抑制问题.展开更多
The dynamical behaviour of a parametrically excited Duffing-van der Pol oscillator under linear-plus-nonlinear state feedback control with a time delay is concerned. By means of the method of averaging together with t...The dynamical behaviour of a parametrically excited Duffing-van der Pol oscillator under linear-plus-nonlinear state feedback control with a time delay is concerned. By means of the method of averaging together with truncation of Taylor expansions, two slow-flow equations on the amplitude and phase of response were derived for the case of principal parametric resonance, it is shown that the stability condition for the trivial solution is only associated with the linear terms in the original systems besides the amplitude and frequency of parametric excitation. And the trivial solution can be stabilized by appreciate choice of gains and time delay in feedback control. Different from the case of the trivial solution, the stability condition for nontrivial solutions is also associated with nonlinear terms besides linear terms in the original system. It is demonstrated that nontrivial steady state responses may lose their stability by saddle-node (SN) or Hopf bifurcation (HB) as parameters vary. The simulations, obtained by numerically integrating the original system, are in good agreement with the analytical results.展开更多
This paper proposes an impulsive control scheme for chaotic systems consisting of Van der Pol oscillators coupled to linear oscillators (VDPL) based on their Takagi-Sugeno (T-S) fuzzy models. A T-S fuzzy model is ...This paper proposes an impulsive control scheme for chaotic systems consisting of Van der Pol oscillators coupled to linear oscillators (VDPL) based on their Takagi-Sugeno (T-S) fuzzy models. A T-S fuzzy model is utilized to represent the chaotic VDPL system. By using comparison method, a general asymptotical stability criterion by means of linear matrix inequality (LMI) is derived for the T-S fuzzy model of VDPL system with impulsive effects. The simulation results demonstrate the effectiveness of the proposed scheme.展开更多
In this paper, phase synchronization and the frequency of two synchronized van der Pol oscillators with delay coupling are studied. The dynamics of such a system are obtained using the describing function method, and ...In this paper, phase synchronization and the frequency of two synchronized van der Pol oscillators with delay coupling are studied. The dynamics of such a system are obtained using the describing function method, and the necessary conditions for phase synchronization are also achieved. Finding the vicinity of the synchronization frequency is the major advantage of the describing function method over other traditional methods. The equations obtained based on this method justify the phenomenon of the synchronization of coupled oscillators on a frequency either higher, between, or lower than the highest, in between, or lowest natural frequency of the aggregate oscillators. Several numerical examples simulate the different cases versus the various synchronization frequency delays.展开更多
In this paper, a class of n coupled van der Pol oscillator model with delays is considered. By employing an analysis approach, some sufficient conditions to guarantee the existence of stability and oscillations for th...In this paper, a class of n coupled van der Pol oscillator model with delays is considered. By employing an analysis approach, some sufficient conditions to guarantee the existence of stability and oscillations for themodel are obtained. Examples are provided to demonstrate the results.展开更多
In this paper, a powerful analytical method, called He’s homotopy perturbation method is applied to obtaining the approximate periodic solutions for some nonlinear differential equations in mathematical physics via V...In this paper, a powerful analytical method, called He’s homotopy perturbation method is applied to obtaining the approximate periodic solutions for some nonlinear differential equations in mathematical physics via Van der Pol damped non-linear oscillators and heat transfer. Illustrative examples reveal that this method is very effective and convenient for solving nonlinear differential equations. Comparison of the obtained results with those of the exact solution, reveals that homotopy perturbation method leads to accurate solutions.展开更多
This paper proposes a Van der Pol (VDP) oscillator screening for peripheral arterial disease (PAD) in patients with diabetes mellitus. The long-term elevated blood sugar levels produce a high risk of peripheral neurop...This paper proposes a Van der Pol (VDP) oscillator screening for peripheral arterial disease (PAD) in patients with diabetes mellitus. The long-term elevated blood sugar levels produce a high risk of peripheral neuropathy and peripheral vascular disease, especially in the foot of a diabetic. Early detection is important, in order to prevent foot problems for diabetic patients with PAD. Photoplethysmography (PPG) is a non-invasive method for the detection of blood volume changes in peripheral arteries. Because of changes in the resistance-compliance, the rise time and transit time for the PPG signals increase and change in their shape are highly correlated with PAD severity. In this study, the Burg autoregressive (AR) method is used to determine the characteristic frequencies of the right-and left-side PPG signals. For bilateral frequency spectra, the VDP oscillator uses asynchronous signals. This produces damped sinusoidal responses and the oscillation overshoot (OS) is an approximating function only of the damped factor. This index is used to estimate the degree of PAD, including normal the condition and diabetic patients with PAD. The results show that the proposed method is efficient and more accurate in the estimation of PAD.展开更多
基金supported by the National Natural Science Foundation of China(No.11772148,12172166 and 11872201)China Postdoctoral Science Foundation(No.2013T60531)。
文摘Chaotic dynamics of the van der Pol-Duffing oscillator subjected to periodic external and parametric excitations with delayed feedbacks are investigated both analytically and numerically in this manuscript.With the Melnikov method,the critical value of chaos arising from homoclinic or heteroclinic intersections is derived analytically.The feature of the critical curves separating chaotic and non-chaotic regions on the excitation frequency and the time delay is investigated analytically in detail.The monotonicity of the critical value to the excitation frequency and time delay is obtained rigorously.It is presented that there may exist a special frequency for this system.With this frequency,chaos in the sense of Melnikov may not occur for any excitation amplitudes.There also exists a uncontrollable time delay with which chaos always occurs for this system.Numerical simulations are carried out to verify the chaos threshold obtained by the analytical method.
基金support from the Alexander von Humboldt Foundation, Germany the British Academy, the Royal Society of London and the Engineering and Physical Sciences Research Council, U.K., through the Newton International Fellowship
文摘In this paper,we propose a backstepping approach for the synchronization and control of modified Van-der Pol Duffing oscillator circuits.The method is such that one controller function that depends essentially on available circuit parameters that is sufficient to drive the two coupled circuits to a synchronized state as well achieve the global stabilization of the system to its regular dynamics.Numerical simulations are given to demonstrate the effectiveness of the technique.
文摘The principal resonance of Van der Pol-Duffing oscillator to combined deterministic and random parametric excitations is investigated. The method of multiple scales was used to determine the equations of modulation of amplitude and phase. The behavior, stability and bifurcation of steady state response were studied. Jumps were shown to occur under some conditions. The effects of damping, detuning, bandwidth, and magnitudes of deterministic and random excitations are analyzed. The theoretical analysis were verified by numerical results.
文摘研究了 Van der Pol-Duffing振子在简谐与随机噪声联合激励下的响应问题。用参数变换法使方程出现小参数 ,用多尺度法分离系统的快变项 ,讨论系统的阻尼项、非线性项和随机项等参数对系统响应的影响。理论分析和数值模拟表明 ,当随机激励强度增大时 ,系统的响应可从一个极限环变为一个扩散的极限环 ;在一定的条件下 ,系统可有两个稳定的稳态解及随机跳跃现象。
文摘研究了Van der Pol-Duffing振子的混沌动力学行为,应用直接微扰法构造了系统的通解,由该通解获得了预测混沌出现的Melnikov判据.在非微扰情形,相图和相应Poincaré截面的演化结果表明:系统阻尼和外驱动力的变化都可以导致系统由倍周期分叉进入混沌状态,当频率参数取相同值时,系统混沌被完全抑制.
文摘研究了改进型Van der Pol-Duffing混沌振子的同步问题。当驱动系统的参数已知时,根据Lyapunov稳定性理论,设计了一个线性反馈控制器,使两个相同的改进型Van der Pol-Duffing混沌振子同步,并得出了保守性较小的同步条件;当驱动系统的参数未知时,利用自适应控制方法,选择了适当的自适应律,构造了两个简单的控制器,使响应系统与驱动系统同步,并同时实现了驱动系统中未知参数的辨识。通过数值仿真,表明了这些方法的有效性。
文摘用平均法研究了含分数阶导数项的van der Pol-Duffing振子的动力学行为和力传递率。得到了主共振时振子的一阶解析解、定常解幅频曲线和相频曲线的解析表达式,进一步通过与数值解作对比,验证了解析解的正确性,分析了不同参数对幅频曲线和力传递率的影响。结果表明:解析解与数值解吻合良好;在无量纲情况下,共振区分数阶项系数、非线性参数、分数阶阶次、阻尼比对幅频曲线和力传递率的共振峰值均有抑制作用;不同频率区段参数对隔振效果的影响不同,在低频隔振区非线性参数和幅值越小隔振效果越好,此外阻尼比对力传递率影响很小;在高频隔振区增大非线性参数、幅值和阻尼比有助于提高隔振效果。
基金FANEDD of China (200430)the National Natural Science Foundation of China (10372116,10532050)
文摘In this paper, a modified averaging scheme is presented for a class of time-delayed vibration systems with slow variables. The new scheme is a combination of the averaging techniques proposed by Hale and by Lehman and Weibel, respectively. The averaged equation obtained from the modified scheme is simple enough but it retains the required information for the local nonlinear dynamics around an equilibrium. As an application of the present method, the delay value for which a secondary Hopf bifurcation occurs is successfully located for a delayed van der Pol oscillator.
文摘传统方法检测微弱信号具有一定的困难,利用混沌振子对微弱信号敏感以及对强噪声具有良好免疫力的特性,提出基于耦合Van der Pol-Duffing振子系统检测微弱信号的新方法。对比不同参数下耦合系统的动力学行为,通过分岔图和二分法确定临界阈值,保证阈值搜索速度和阈值精度。阐述基于相图的微弱信号检测原理,通过从混沌态到周期态的转变成功检测淹没在强噪声中的微弱信号,信噪比门限达到–30 d B。同时考察不同精度幅值下噪声对系统状态的影响,不同频率信号以及相移对检测的影响。仿真结果表明,该耦合系统在强噪声条件下对微弱信号敏感,用于检测微弱信号是可行的。
文摘研究含时滞的大规模van der Pol-Duffing耦合振子系统的非线性动力学.通过讨论特征方程根分布情况确定系统的稳定性,并在耦合时滞和强度平面上给出振幅死亡区域.结合数值算例,揭示同步和异步周期振荡、概周期运动以及混沌吸引子等现象.基于非线性振子电路和时滞电路,构建电路实验平台,有效验证理论和数值结果.研究结果表明,时滞可以显著影响系统动力学特性,如诱发振幅死亡、稳定性切换以及复杂振荡等.
文摘研究了同时含有平方项和高次幂项的Van der Pol-Duffing系统的混沌行为及混沌控制问题,数值仿真分析了该系统存在的典型非线性动力学行为.主要采用单初始点分岔分析方法、最大Lyapunov指数和Poincare映射方法,从不同侧面揭示了在周期激振力作用下系统的周期运动、混沌运动,以及运动形式的演化过程,并用x|x|控制方法实现了系统的混沌抑制问题.
基金Project supported by the Scientific Research Foundation for Returned Overseas Chinese Scholar of Ministry of Eduction, China (No.2006-331)
文摘The dynamical behaviour of a parametrically excited Duffing-van der Pol oscillator under linear-plus-nonlinear state feedback control with a time delay is concerned. By means of the method of averaging together with truncation of Taylor expansions, two slow-flow equations on the amplitude and phase of response were derived for the case of principal parametric resonance, it is shown that the stability condition for the trivial solution is only associated with the linear terms in the original systems besides the amplitude and frequency of parametric excitation. And the trivial solution can be stabilized by appreciate choice of gains and time delay in feedback control. Different from the case of the trivial solution, the stability condition for nontrivial solutions is also associated with nonlinear terms besides linear terms in the original system. It is demonstrated that nontrivial steady state responses may lose their stability by saddle-node (SN) or Hopf bifurcation (HB) as parameters vary. The simulations, obtained by numerically integrating the original system, are in good agreement with the analytical results.
文摘This paper proposes an impulsive control scheme for chaotic systems consisting of Van der Pol oscillators coupled to linear oscillators (VDPL) based on their Takagi-Sugeno (T-S) fuzzy models. A T-S fuzzy model is utilized to represent the chaotic VDPL system. By using comparison method, a general asymptotical stability criterion by means of linear matrix inequality (LMI) is derived for the T-S fuzzy model of VDPL system with impulsive effects. The simulation results demonstrate the effectiveness of the proposed scheme.
文摘In this paper, phase synchronization and the frequency of two synchronized van der Pol oscillators with delay coupling are studied. The dynamics of such a system are obtained using the describing function method, and the necessary conditions for phase synchronization are also achieved. Finding the vicinity of the synchronization frequency is the major advantage of the describing function method over other traditional methods. The equations obtained based on this method justify the phenomenon of the synchronization of coupled oscillators on a frequency either higher, between, or lower than the highest, in between, or lowest natural frequency of the aggregate oscillators. Several numerical examples simulate the different cases versus the various synchronization frequency delays.
文摘In this paper, a class of n coupled van der Pol oscillator model with delays is considered. By employing an analysis approach, some sufficient conditions to guarantee the existence of stability and oscillations for themodel are obtained. Examples are provided to demonstrate the results.
文摘In this paper, a powerful analytical method, called He’s homotopy perturbation method is applied to obtaining the approximate periodic solutions for some nonlinear differential equations in mathematical physics via Van der Pol damped non-linear oscillators and heat transfer. Illustrative examples reveal that this method is very effective and convenient for solving nonlinear differential equations. Comparison of the obtained results with those of the exact solution, reveals that homotopy perturbation method leads to accurate solutions.
文摘This paper proposes a Van der Pol (VDP) oscillator screening for peripheral arterial disease (PAD) in patients with diabetes mellitus. The long-term elevated blood sugar levels produce a high risk of peripheral neuropathy and peripheral vascular disease, especially in the foot of a diabetic. Early detection is important, in order to prevent foot problems for diabetic patients with PAD. Photoplethysmography (PPG) is a non-invasive method for the detection of blood volume changes in peripheral arteries. Because of changes in the resistance-compliance, the rise time and transit time for the PPG signals increase and change in their shape are highly correlated with PAD severity. In this study, the Burg autoregressive (AR) method is used to determine the characteristic frequencies of the right-and left-side PPG signals. For bilateral frequency spectra, the VDP oscillator uses asynchronous signals. This produces damped sinusoidal responses and the oscillation overshoot (OS) is an approximating function only of the damped factor. This index is used to estimate the degree of PAD, including normal the condition and diabetic patients with PAD. The results show that the proposed method is efficient and more accurate in the estimation of PAD.