共查询到19条相似文献,搜索用时 125 毫秒
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研究了具有同宿轨道、异宿轨道的双势阱Duffing振子在谐和激励与有界噪声摄动下的混沌运动.基于同宿分叉和异宿分叉,由Melnikov理论推导了系统出现混沌运动的必要条件及出现分形边界的充分条件.结果表明:当Wiener过程的强度参数大于某一临界值时,噪声增大了诱发混沌运动的有界噪声的临界幅值,相应地缩小了参数空间的混沌域,且产生混沌运动的临界幅值随着噪声强度的增大而增大.同时数值计算了最大Lyapunov指数,由最大Lyapunov指数为零从另一角度得到了系统出现混沌运动的有界噪声的临界幅值,发现在Wi
关键词:
混沌
同宿和异宿分叉
随机Melnikov方法
最大Lyapunov指数 相似文献
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Lyapunov指数是定量描述非线性动力系统轨道稳定性的主要方法之一,同时也是分析系统分岔行为的常用手段.实际应用中,人们通常只关心Lyapunov指数的正负,并以此来判断系统轨道是否稳定,而对于Lyapunov指数为零,即动力学分岔点处系统的行为特征讨论甚少.本文以几类经典的非线性动力系统为例,针对系统在分岔点处的轨道稳定性进行理论和数值分析.研究发现,不同系统在分岔点处其微扰后的轨道均以幂律,而非指数的形式收敛,呈现出经典物理系统在相变临界点处的慢化行为.通过理论分析,我们解析得到分岔点处计算临界指数的一般公式,并通过数值模拟对理论公式的准确性进行了验证.临界慢化是物理系统在相变点处的普遍现象,文中关于非线性系统在分岔点处临界慢化行为的发现将加深人们对于动力学分岔本质的认识,同时也是对现有教材中关于Lyapunov指数相关知识的有益补充. 相似文献
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The aim is to investigate whether in a structural bistable reaction-diffusion system pattern formation may emerge simultaneously from both steady states. Therefore, a dynamical system is modelled by three coupled nonlinear differential equations from which synergetic ordering may arise. In addition, the nonlinear terms are chosen such that the homogeneous system is governed by the canonical form of a cusp bifurcation in a two-dimensional control space. Thus, structural bistability is established. Based on a linear stability analysis the region of bistability is decomposed into four different domains in the control plane. It is shown that in one of these domains self-organization can lead to pattern formation from both steady states simultaneously. In two other domains self-organization can arise from only one steady state and finally in one domain patterning is impossible. An expression for the wavelength of a spatial structure is derived and discussed in terms of parameters of the system. As a possible application of the present results a crystal under irradiation with particles of high energy is considered. It is demonstrated for the case of steel that the parameters of the system can be chosen such that a two-fold spatial instability for irradiation induced cavities may emerge. 相似文献
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Noticeable positive Doppler effect on optical bistability in an N-type active Raman gain atomic system 下载免费PDF全文
We theoretically investigate the Doppler effect on optical bistability in an N-type active Raman gain atomic system inside an optical ring cavity.It is shown that the Doppler effect can greatly enhance the dispersion and thus create the bistable behaviour or greatly increase the bistable region,which has been known as the positive Doppler effect on optical bistability.In addition,we find that a positive Doppler effect can change optical bistability from the hybrid dispersion-gain type to a dispersive type. 相似文献
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Maciej Antkowiak Rafał Kotyński Krassimir Panajotov Francis Berghmans Hugo Thienpont 《Optical and Quantum Electronics》2007,39(4-6):455-467
We study numerically the temporal and spatial dynamics of light in Bragg gratings in highly nonlinear photonic crystal fibre
for a CW input signal. Our numerical model is based on the plane wave mode solver and a set of nonlinear coupled-mode equations
which we solve using a variation of implicit fourth order Runge-Kutta method. We observe not only bistability of the intensity
versus transmitted and reflected light but also complex dynamics. We demonstrate that for values of input intensity above
the bistable region the steady state may undergo a supercritical Hopf bifurcation. For some ranges of the input intensity
we also observe a coexistence of two periodic attractors. The dynamics found, in particular the features in the bifurcation
diagram, strongly depend on the parameters of the fibre. Consequently, we suggest that by proper design of the photonic crystal
in the cladding we can adjust such nonlinear features of the Bragg gratings as the width of the bistable region, the intensity
at which the bifurcation occurs and also the characteristics of the dynamics at high values of input intensity. 相似文献
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报道了波长为792nm激光二极管端面抽运Tm,Ho:YLF连续激光器的双稳输出特性.在考虑能量传递上转换和基态对2μm激光重吸收的前提下,建立了Tm,Ho:YLF双稳激光器准三能级速率方程理论模型.通过对Tm,Ho:YLF激光器速率方程的求解,理论预见了Tm,Ho:YLF激光器双稳输出的特性,并分析了其产生的机理.进行了激光二极管端面抽运Tm,Ho:YLF激光器双稳输出的实验研究,当激光晶体温度为253K时,双稳区的宽度可达1.6W,跃变点输出功率的跃变量可达82.5mW.通过对比发现理论结果与实验结果比
关键词:
端面抽运
Tm
Ho:YLF晶体
连续输出
光学双稳 相似文献
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Equations governing the behaviour of a single mode high-Q ring cavity are obtained for a coherent driving field (detuned to both cavity and atoms) and inhomogeneously broadened atomic transitions using a Hamiltonian approach. We find the region of bistability and critical points in the homogeneous broadening case. Numerical results including inhomogeneous broadening show that bistability is obtained more readily by detuning both the atomic transition and the cavity mode relative to the driving field. 相似文献
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重点研究了组分的梯度构形对带壳球形颗粒复合介质的光学双稳特性的影响.其中球形颗粒是由非线性核和介电函数具有梯度分布的线性壳组成.对于壳层介电函数具有幂指数分布的情况,通过求解麦克斯韦方程,得到各区域的势能分布函数,从而求得核内电场的数学表达式.数值研究发现,该复合介质的光学双稳阈值和区域与壳层的厚度及壳层的介电幂指数有关,随着壳层厚度增大或幂指数增大,双稳阈值将变宽.此外,还研究了正入射情况下复合材料体系的反射系数随外电场的变化情况, 发现其关系曲线是一条回线.
关键词:
梯度颗粒
复合介质
光学双稳 相似文献