共查询到20条相似文献,搜索用时 15 毫秒
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We present a complete list of nonlinear one-field hyperbolic equations with integrable third-order x and y symmetries. The list includes both equations of the sine-Gordon type and equations linearizable by differential substitutions. 相似文献
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Roman Kozlov 《Communications in Nonlinear Science & Numerical Simulation》2012,17(12):4947-4951
This note can be considered as a supplement to article [8]. Its purpose is twofold. First, to show that symmetries of Itô stochastic differential equations form a Lie algebra. Second, to provide more precise formulation of the relation between symmetries of SDEs and symmetries of the associated Fokker–Planck equation. Relation between first integrals of SDEs and symmetries of the associated Fokker–Planck equation is also considered. 相似文献
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In this work a physical modelling framework is presented, describing the intelligent, non-local, and anisotropic behaviour of pedestrians. Its phenomenological basics and constitutive elements are detailed, and a qualitative analysis is provided. Within this common framework, two first-order mathematical models, along with related numerical solution techniques, are derived. The models are oriented to specific real world applications: a one-dimensional model of crowd–structure interaction in footbridges and a two-dimensional model of pedestrian flow in an underground station with several obstacles and exits. The noticeable heterogeneity of the applications demonstrates the significance of the physical framework and its versatility in addressing different engineering problems. The results of the simulations point out the key role played by the physiological and psychological features of human perception on the overall crowd dynamics. 相似文献
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Michael Kunzinger 《Journal of Mathematical Analysis and Applications》2011,379(1):444-460
We analyze the relationship of generalized conditional symmetries of evolution equations to the formal compatibility and passivity of systems of differential equations as well as to systems of vector fields in involution. Earlier results on the connection between generalized conditional invariance and generalized reduction of evolution equations are revisited. This leads to a no-go theorem on determining equations for operators of generalized conditional symmetry. It is also shown that up to certain equivalences there exists a one-to-one correspondence between generalized conditional symmetries of an evolution equation and parametric families of its solutions. 相似文献
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Hidden symmetries of second-order differential equations whichare invariant under a one-parameter Lie point group and areof the energy-conserving form are analysed as an inverse problemfor some particular cases. These hidden symmetries occur asadditional one-parameter lie point group symmetries in the reducedfirst-order differential equations. 相似文献
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D. J. Kaup 《Journal of Nonlinear Science》1993,3(1):427-443
Summary Using standard multiscale techniques, a first-order perturbation theory for SBS is developed. In the presence of small damping,
we find that there is a stationary solution for a soliton which is a fixed point. The velocity of this soliton is determined
by the damping coefficients. In addition, there is also a constant shift in the pump intensity in the region between the front
of the backward moving soliton and the forward light cone of the pump. 相似文献
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E. N. Dancer 《Mathematische Annalen》1983,262(4):473-486
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This paper presents a partial classification for C∞ type-changing symplectic Monge-Ampère partial differential equations (PDEs) that possess an infinite set of first-order intermediate PDEs. The normal forms will be quasi-linear evolution equations whose types change from hyperbolic to either parabolic or to zero. The zero points can be viewed as analogous to singular points in ordinary differential equations. In some cases, intermediate PDEs can be used to establish existence of solutions for ill-posed initial value problems. 相似文献
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E. M. Vorob'ev 《Acta Appl Math》1991,23(1):1-24
The method of reduction previously known in the theory of Hamiltonian systems with symmetries is developed in order to obtain exact group-invariant solutions of systems of partial differential equations. This method leads to representations of quotient equations which are very convenient for the systematic analysis of invariant solutions of boundary value problems. In the case of partially invariant solutions, necessary and sufficient conditions of their invariance with respect to subalgebras of symmetry algebras are given. The concept of partial symmetries of differential equations is considered. 相似文献
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M.L. Gandarias M.S. Bruzn 《Communications in Nonlinear Science & Numerical Simulation》2010,15(2):291-299
The Type II hidden symmetries are extra symmetries in addition to the inherited symmetries of the differential equations when the number of independent and dependent variables is reduced by a Lie-point symmetry. In [Gandarias RML. Type-II hidden symmetries through weak symmetries for nonlinear partial differential equations. J Math Anal Appl 2008;348:752–9] it was shown that the provenance of the Type II Lie point hidden symmetries found for differential equations can be explained by considering weak symmetries or conditional symmetries of the original PDE.In this paper we analyze the connection between one of the methods analyzed in [Abraham-Shrauner B, Govinder KS. Provenance of Type II hidden symmetries from nonlinear partial differential equations. J Nonlin Math Phys 2006;13:612–22] and the weak symmetries of some partial differential equations in order to determine the source of these hidden symmetries. We have considered some of the models presented in [Abraham-Shrauner B, Govinder KS. Provenance of Type II hidden symmetries from nonlinear partial differential equations. J Nonlin Math Phys 2006;13:612–22], as well as the linear two-dimensional and three-dimensional wave equations [Abraham-Shrauner B, Govinder KS, Arrigo JA. Type II hidden symmetries of the linear 2D and 3D wave equations. J h Phys A Math Theor 2006;39:5739–47]. 相似文献
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A. G. Meshkov 《Theoretical and Mathematical Physics》2009,161(2):1471-1484
We list eleven vector hyperbolic equations that have third-order symmetries with respect to both characteristics. This list exhausts the equations with at least one symmetry of a divergence form. We integrate four equations in the list explicitly, bring one to a linear form, and bring four more to nonlinear ordinary nonautonomous systems. We find the Bäcklund transformations for six equations. 相似文献
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M.L. Gandarias 《Journal of Mathematical Analysis and Applications》2008,348(2):752-759
The Type-II hidden symmetries are extra symmetries in addition to the inherited symmetries of the differential equations when the number of independent and dependent variables is reduced by a Lie point symmetry. In [B. Abraham-Shrauner, K.S. Govinder, Provenance of Type II hidden symmetries from nonlinear partial differential equations, J. Nonlinear Math. Phys. 13 (2006) 612-622] Abraham-Shrauner and Govinder have analyzed the provenance of this kind of symmetries and they developed two methods for determining the source of these hidden symmetries. The Lie point symmetries of a model equation and the two-dimensional Burgers' equation and their descendants were used to identify the hidden symmetries. In this paper we analyze the connection between one of their methods and the weak symmetries of the partial differential equation in order to determine the source of these hidden symmetries. We have considered the same models presented in [B. Abraham-Shrauner, K.S. Govinder, Provenance of Type II hidden symmetries from nonlinear partial differential equations, J. Nonlinear Math. Phys. 13 (2006) 612-622], as well as the WDVV equations of associativity in two-dimensional topological field theory which reduces, in the case of three fields, to a single third order equation of Monge-Ampère type. We have also studied a second order linear partial differential equation in which the number of independent variables cannot be reduced by using Lie symmetries, however when is reduced by using nonclassical symmetries the reduced partial differential equation gains Lie symmetries. 相似文献
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R. Sahadevan 《Journal of Mathematical Analysis and Applications》2006,324(1):199-215
A method to derive the continuous nonpoint symmetries of ordinary difference equations (OΔE) of order two and higher is presented. A partial classification of second and fourth order difference equations that admit nonpoint symmetries both rational and polynomial forms which are quadratic in each variable is reported. Also, exploiting the obtained symmetries, it is shown how to construct integrals of motion or invariant for each of the considered equations. The question of integrability of the fourth order difference equations possessing the above type of nonpoint symmetries has also been briefly discussed. 相似文献
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G. Chavchanidze 《Journal of Mathematical Sciences》2009,160(6):693-696
We investigate a one-parameter non-Noether symmetry group of the modified Boussinesq equations and show that this symmetry
naturally yields an infinite sequence of conservation laws.
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 59, Algebra
and Geometry, 2008. 相似文献
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In this article we investigate the equivalence of underdetermined differential equations and differential equations with deviations
of second order with respect to the pseudogroup of transformations = φ(x), ȳ = ȳ() = L(x) + y(x), = () = M(x) + z(x). Our main aim is to determine such equations that admit a large pseudogroup of symmetries. Instead the common direct calculations,
we use some more advanced tools from differential geometry, however, our exposition is self-contained and only the most fundamental
properties of differential forms are employed.
This research has been conducted at the Department of Mathematics as part of the research project CEZ: Progressive reliable
and durable structures, MSM 0021630519. 相似文献