共查询到20条相似文献,搜索用时 699 毫秒
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目前基于混沌系统的彩色图像加密算法并未充分地考虑图像时频域特征,并且具有密钥空间小的缺点,对此提出了一种基于离散正交S变换域的彩色图像编解码技术。将图像分解为RGB三色通道,对每个通道分别进行离散正交S变换(DOST);对各通道使用一级离散小波变换(DWT),将每个通道分解为四个子带;使用DWT分解各子带;对奇异值进行乘法运算,使用新奇异值重构所有的子带。可将DOST的子带数量、奇异值参数以及DWT子带的排列顺序作为密钥,从密钥获取难度极高。实验结果表明,方法具有较好的加密效果,安全性优于其他的算法。 相似文献
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针对电子连续性方程的离散代数方程组,对离散线性系统的矩阵进行分析,得到矩阵的三类特点;针对大规模电子连续性方程的离散方程组,采用预处理Krylov子空间方法进行求解,并比较和分析几类预处理方法的效果。结果表明:代数多重网格(AMG)预处理Krylov子空间方法在求解离散电子连续性方程方面非常有效。开展AMG预处理Krylov子空间方法求解离散电子连续性方程的大规模并行可扩展性测试,比较和分析了AMG方法中三类关键算法参数的选取。 相似文献
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由一个正弦映射和一个三次方映射通过非线性耦合,构成一个新的二维正弦离散映射. 基于此二维正弦离散映射得到系统的不动点以及相应的特征值,分析了系统的稳定性,研究了系统的复杂非线性动力学行为及其吸引子的演变过程. 研究结果表明:此二维正弦离散映射中存在复杂的对称性破缺分岔、Hopf分岔、倍周期分岔和周期振荡快慢效应等非线性物理现象. 进一步根据控制变量变化时系统的分岔图、Lyapunov指数图和相轨迹图分析了系统的分岔模式共存、快慢周期振荡及其吸引子的演变过程,通过数值仿真验证了理论分析的正确性.
关键词:
正弦离散映射
对称性破缺分岔
Hopf分岔
吸引子 相似文献
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本文研究离散差分序列变质量Hamilton系统的Lie对称性与Noether守恒量. 构建了离散差分序列变质量Hamilton系统的差分动力学方程, 给出了离散差分序列变质量Hamilton系统差分动力学方程在无限小变 换群下的Lie对称性的确定方程和定义, 得到了离散力学系统Lie对称性导致Noether守恒量的条件及形式, 举例说明结果的应用.
关键词:
离散力学
Hamilton系统
Lie对称性
Noether守恒量 相似文献
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The closed form of solutions of Kac-van Moerbeke lattice and
self-dual network equations are considered by proposing
transformations based on Riccati equation, using symbolic
computation. In contrast to the numerical computation of
travelling wave solutions for differential difference
equations, our method obtains exact solutions which have physical relevance. 相似文献
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Some new exact solutions of the generalized Lienard equation are obtained, and the solutions of the equation are applied to
solve nonlinear wave equations with nonlinear terms of any order directly. The generalized one-dimensional Klein-Gordon equation,
the generalized Ablowitz (A) equation and the generalized Gerdjikov-Ivanov (GI) equation are investigated and abundant new
exact travelling wave solutions are obtained that include solitary wave solutions and triangular periodic wave solutions.
相似文献
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In this paper, we generalize the extended tanh-function approach, which used to find new exact travelling wave solutions of
nonlinear partial differential equations (NPDES) or coupled nonlinear partial differential equations, to nonlinear differential-difference
equations (NDDES). As illustration, we discuss some Toda lattice equations, and solitary wave and periodic wave solutions
of these Toda lattice equations are obtained by means of the extended tanh-function approach.
PACS numbers: 05.45.Yv, 02.30.Jr, 02.30.Ik. 相似文献
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DAI Chao-Qing ZHANG Jie-Fang 《理论物理通讯》2006,46(1):23-27
In this paper, we generalize the extended tanh-function approach, which was used to find new exact travelling wave solutions of nonlinear partial differential equations or coupled nonlinear partial differential equations, to nonlinear differential-difference equations. As illustration, two series of exact travelling wave solutions of the discrete sine-Gordon equation are obtained by means of the extended tanh-function approach. 相似文献
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DAI Chao-Qing ZHANG Jie-Fang 《理论物理通讯》2006,46(7)
In this paper, we generalize the extended tanh-function approach, which was used to find new exact travelling wave solutions of nonlinear partial differential equations or coupled nonlinear partial differential equations, to nonlinear differential-difference equations. As illustration, two series of exact travelling wave solutions of the discrete sine-Gordon equation are obtained by means of the extended tanh-function approach. 相似文献
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Huiqun Zhang 《Reports on Mathematical Physics》2007,60(1):97-106
A direct algebraic method is introduced for constructing exact travelling wave solutions of nonlinear partial differential equations with complex phases. The scheme is implemented for obtaining multiple soliton solutions of the generalized Zakharov equations, and then new exact travelling wave solutions with complex phases are obtained. In addition, by using new exact solutions of an auxiliary ordinary differential equation, new exact travelling wave solutions for the generalized Zakharov equations are obtained. 相似文献
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New Exact Travelling Wave Solutions to Kundu Equation 总被引:1,自引:0,他引:1
Based on a first-order nonlinear ordinary differential equation with Six-degree nonlinear term, we first present a new auxiliary equation expansion method and its algorithm. Being concise and straightforward, the method is applied to the Kundu equation. As a result, some new exact travelling wave solutions are obtained, which include bright and dark solitary wave solutions, triangular periodic wave solutions, and singular solutions. This algorithm can also be applied to other nonlinear evolution equations in mathematical physics. 相似文献
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Based on a first-order nonlinear ordinary differential equation with six-degree nonlinear term, we first present a new auxiliary equation expansion method and its algorithm. Being concise and straightforward, the method is applied to the Kundu equation. As a result, some new exact travelling wave solutions are obtained, which include bright and dark solitary wave solutions, triangular periodic wave solutions, and singular solutions. This algorithm can also be applied to other nonlinear evolution equations in mathematical physics. 相似文献
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Some new exact travelling wave and period solutions of
discrete nonlinear Schrödinger equation are found
by using a hyperbolic tangent function approach, which was usually
presented to find exact travelling wave solutions of certain
nonlinear partial differential models. Now we can further extend
the new algorithm to other nonlinear differential-different models. 相似文献