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从微分方程群理论分析角度,研究了一类含有3个任意函数和2个幂非线性项的变系数非线性波动方程.由于方程具有很强的任意性和非线性项,可通过等价性变换寻找方程的不变对称分类.首先给出了等价性变换的一般结果,其中包括一些包含任意元的非局部变换.然后对所研究的方程,利用广义扩展等价群和条件等价群给出了方程的完全对称分类.最后获得并分析了方程的特殊类相似解. 相似文献
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利用古典无穷小算法、等价性变换技巧和有限维抽象李代数的分类理论,给出了一般拟线性三阶演化方程在半单和一维至四维可解李代数下不变的群分类.证明了只存在3个不等价的方程在三维单李代数下不变,而且进一步证明在所有半单李代数下不变的不等价方程只有这3个.另外,还证明了存在2个、5个、29个和26个不等价的方程,分别在一维至四维可解李代数下不变. 相似文献
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Lie symmetry reduction of some truly "variable coefficient" wave equations which are singled out from a class of (1 + 1)-dimensional variable coefficient nonlinear wave equations with respect to one and two-dimensional algebras is carried out. Some classes of exact solutions of the investigated equations are found by means of both the reductions and some modern techniques such as additional equivalent transformations and hidden symmetries and so on. Conditional symmetries are also discussed. 相似文献
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Conservation laws for variable coefficient nonlinear wave equations with power nonlinearities 下载免费PDF全文
Conservation laws for a class of variable coefficient nonlinear wave equations with power nonlinearities are investigated.The usual equivalence group and the generalized extended one including transformations which are nonlocal with respect to arbitrary elements are introduced.Then,using the most direct method,we carry out a classification of local conservation laws with characteristics of zero order for the equation under consideration up to equivalence relations generated by the generalized extended equivalence group.The equivalence with respect to this group and the correct choice of gauge coefficients of the equations play the major roles for simple and clear formulation of the final results. 相似文献
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Group Classification and Exact Solutions of a Class of Variable Coefficient Nonlinear Wave Equations 下载免费PDF全文
Complete group classification of a class of variable coefficient (1+1)-dimensional wave equations is performed. The possible additional equivalence transformations between equations from the class under consideration and the conditional equivalence groups are also investigated. These allow simplification of the results of the classification and further applications of them. The derived Lie symmetries are used to construct exact solutions of special forms of these equations via the classical Lie method. Nonclassical symmetries of the wave equations are discussed. 相似文献
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Group classification of quasilinear third-order evolution equations is given by using the classical infinitesimal Lie method, the technique of equivalence transformations, and the theory of classification of abstract low-dimensional Lie algebras. We show that there are three equations admitting simple Lie algebras of dimension three. All non-equivalent equations admitting simple Lie algebras are nothing but these three. Furthermore, we also show that there exist two, five, twenty-nine and twenty-six non- equivalent third-order nonlinear evolution equations admitting one-, two-, three-, and four-dimensional solvable Lie algebras, respectively. 相似文献
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