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121.
122.
本文基于生成函数的Taylor展开式及逐步简化步骤,提出了计算偏微分方程组的Lie群与高阶对称群的Taylor多项式算法,把标准算法中的求解超定偏微分方程组的问题转化为求解代数方程组的问题,降低了求解的难度,提高了计算效率,并且易用计算机代数系统在计算机上全过程实现,并得到重要的对称群 相似文献
123.
应用分离变量法,得到了一类二阶微分方程初值问题存在无穷多个非负解的充分必要条件,并给出了所有的无穷多个非负解.。 相似文献
124.
Zhaoxia Liu 《Journal of Mathematical Analysis and Applications》2011,382(2):731-747
In this paper, we consider the elliptic system of two equations in H1(RN)×H1(RN):
125.
126.
Patrizio Cintioli 《Mathematical Logic Quarterly》2011,57(5):517-523
Given a reducibility ?r, we say that an infinite set A is r‐introimmune if A is not r‐reducible to any of its subsets B with |A\B| = ∞. We consider the many‐one reducibility ?m and we prove the existence of a low1 m‐introimmune set in Π01 and the existence of a low1 bi‐m‐introimmune set. 相似文献
127.
Jaume Giné 《Journal of Applied Analysis & Computation》2011,1(4):487-496
In this short survey we study the narrow relation between the center problem and the Lie symmetries. It is well known that an analytic vector eld X having a non-degenerate center has a non-trivial analytic Lie symmetry in a neighborhood of it, i.e. there exists an analytic vector eld Y such that [X;Y] = \(\mu\)X. The same happens for a nilpotent center with an analytic rst integral as can be seen from the last results about nilpotent centers. From the last results for nilpotent and degenerate centers it also can be proved that any nilpotent or degenerate center has a trivial smooth (of class \(C^{\infty} \) ) ) Lie symmetry. Remains open if always exists also a non-trivial Lie symmetry for any nilpotent and degenerate center. 相似文献
128.
A thermodynamic approach with internal variables using Lagrange formalism. Part I: General framework 总被引:1,自引:0,他引:1
Rachid Rahouadj Jean-Franois Ganghoffer Christian Cunat 《Mechanics Research Communications》2003,30(2):109-117
We present some reflections on the application of the Lagrangian formalism for continuous media locally uniform subjected to internal irreversible evolutions. The Lagrangian density, defined as the time derivative of a non-equilibrium thermodynamic potential, [Thermodynamics of Relaxation Processes using Internal variables within a Lagrange-formalism. P. Germain’s Anniversary Volume 2000. Contiuum Thermomechanics: the Art and Science of Modeling Matter’s Behaviour, 2000], contains all the symmetry properties of the system. The generalised Lagrange co-ordinates correspond to the state and internal variables of the time derivative of the generalised Gibbs potential. The latter being used within the framework of the De Donder’s method, must also account for the memory effect of the physical medium.This first part is devoted to the thermodynamic framework called the distribution of non-linear relaxations approach (DNLR) developed by C. Cunat on the basis of the generalised Gibbs’ relation. 相似文献
129.
Rachid Rahouadj Jean-Franois Ganghoffer Christian Cunat 《Mechanics Research Communications》2003,30(2):119-123
In the first part of this contribution, the Lie-symmetries of the principle of least action associated to the constitutive equations of the DNLR formalism of relaxation have been presented. We examine in this second part the continuous symmetries corresponding to the simple case of stress relaxation under isothermal conditions. The well-known principle of time/temperature equivalence is discussed in terms of variational symmetry for the Jacobi’s action functional, and connected to the Onsager’s relation near the thermodynamic equilibrium. 相似文献
130.
R.P. Malik 《Annals of Physics》2003,307(1):1-40
Some of the key cohomological features of the two (1 + 1)-dimensional (2D) free Abelian- and self-interacting non-Abelian gauge theories (having no interaction with matter fields) are briefly discussed first in the language of symmetry properties of the Lagrangian densities and the same issues are subsequently addressed in the framework of superfield formulation on the four (2 + 2)-dimensional supermanifold. Special emphasis is laid on the on-shell- and off-shell nilpotent (co-)BRST symmetries that emerge after the application of (dual) horizontality conditions on the supermanifold. The (anti-)chiral superfields play a very decisive role in the derivation of the on-shell nilpotent symmetries. The study of the present superfield formulation leads to the derivation of some new symmetries for the Lagrangian density and the symmetric energy-momentum tensor. The topological nature of the above theories is captured in the framework of superfield formulation and the geometrical interpretations are provided for some of the topologically interesting quantities. 相似文献