Weakly perturbed boundary-value problems for differential equations in a Banach space

We consider boundary-value problems for a system of ordinary differential equations with a small parameter ε in the equations and boundary conditions. We establish conditions for the bifurcation of solutions of a weakly perturbed linear boundary-value problem in a Banach space.     

Nonautonomous Periodic Boundary-Value Problems in a Special Critical Case

We study the problem of finding conditions for the existence of solutions of weakly nonlinear periodic boundary-value problems for systems of ordinary differential equations and the construction of these solutions. We consider the special critical case where the equation for generating amplitudes of a weakly nonlinear periodic boundary-value problem reduces to the identity. We construct a new classification of critical cases and an iteration algorithm for the construction of solutions of weakly nonlinear periodic boundary-value problems in a special critical case.     

Nonlinear Noetherian boundary-value problems in the critical case

We establish necessary and sufficient conditions for the existence of solutions of a weakly nonlinear Noetherian boundary-value problem for a system of ordinary differential equations in the critical case.     

On a Countable-Point Nonlinear Boundary-Value Problem on a Semiaxis for Ordinary Differential Equations in the Space of Bounded Numerical Sequences

We use the idea of the Samoilenko numerical-analytic method for the investigation of a nonlinear boundary-value problem with an unbounded countable set of boundary moments on the positive semiaxis in the case where the differential equation and boundary conditions are defined in the Banach space of bounded numerical sequences.     

Autonomous noetherian boundary-value problem in the critical case

We establish constructive conditions for the existence of solutions of an autonomous Noetherian weakly nonlinear boundary-value problem for a system of ordinary differential equations in the critical case and develop a modified iterative procedure for finding its solutions.     

关于以应力表示的弹性力学边值问题

以六个应力分量表示的弹性力学边值问题由九个方程和三个边条件组成,本文探讨了它等价于六个方程和六个边界条件的可能情形和不可能情形。     

Boundary-value problems for differential equations unresolved with respect to the derivative in the space of bounded number sequences

We study a nonlinear countable-point boundary-value problem for a differential equation unresolved with respect to the derivative. This equation and a nonlinear boundary condition are defined in the Banach space of bounded number sequences. We study the reducibility of the posed problem to a multipoint boundary-value problem in a finite-dimensional space. __________ Translated from Neliniini Kolyvannya, Vol. 10, No. 3, pp. 391–415, July–September, 2007.     

Theory of large-strain torsion of prismatic bodies with moment stresses

The problem of the torsion and tension-compression of a prismatic bar with a stress-free lateral surface is studied using three-dimensional elasticity theory for materials with moment stresses. A substitution is found that allows one to separate one variable in the nonlinear equilibrium equations for a Cosserat continuum and boundary conditions on the lateral surface. This substitution reduces the original spatial problem of the equilibrium of a micropolar body to a two-dimensional nonlinear boundary-value problem for a plane region shaped like the cross section of the prismatic bar. Variational formulations of the two-dimensional problem for the section are given that differ in the sets of varied functions and the constraints imposed on their boundary values. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 4, pp. 167–175, July–August, 2006.     

Theory of diffraction of weak shock waves

A numerical solution is considered to the universal nonlinear boundary-value diffraction problem which occurs in various problems of weak interaction [1, 2] in the asymptotic analysis of the flow in a region with large gradients of the parameters near the point of intersection of the incident, diffracted, and reflected waves. The analytical solutions to this type of problem usually approximately satisfy the conditions on the diffracted front, the position of which is not known beforehand, but is found along with the solution. In the present paper, the problem is solved by the numerical method of [3], which reduces the initial boundary-value problem for the system of short-wave equations with an unknown boundary to the solution of a series of boundary-value problems with a fixed boundary. The problem of the diffraction of a weak shock wave on a wedge with a finite apex angle is considered as an application of the solution. The data calculated by the asymptotic theory agree significantly better with the experimental data [5] than the theoretical data of [4].Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6. pp. 176–178, November–December, 1984.     

On the block element method in nonstationary problems

The block element method is used to study and solve the boundary-value problems of continuum mechanics for materials with time-varying characteristics. An example of constructing a block element is given for a boundary-value problem related to nonstationary behavior of a continuum in a four-dimensional space, with time taken into account. Pseudodifferential equations describing the block element parameters are derived. It is shown that, in the theory of block elements, the difference between the boundary and initial conditions in a nonstationary boundary-value problem disappears.     

Nonlinear problems of the thermal conductivity equation

The asymptotic behavior of solutions of parabolic equations at infinite times has been investigated for various cases [1–6]. Two initial boundary-value problems are considered in this paper. The solution of the thermal conductivity equation with a nonlinear right-hand side is found, including also nonlinear boundary conditions. It is shown that the solution of the corresponding problem tends either to a stable, steady-state solution, or to a periodic solution, depending on the initial values of the functions and constants appearing in the conditions of the problem. Other papers [7, 8] are devoted to finding the periodic solutions of these two problems encountered in hydrodynamics (diffusion, underground hydrodynamics), and to studying the asymptotic behavior of the corresponding initial boundary problems.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 123–128, May–June, 1972.     

Nonlinear effects associated with the mutual displacement of two gases in a porous medium

The cyclic bidirectional process of isothermal flow of a binary singlephase compressible gas mixture in a porous medium accompanied by diffusion-dispersion mass transfer is considered. On the basis of the equations of multiphase multicomponent isothermal flow a system of two nonlinear partial differential equations with nonlinear boundary conditions corresponding to a given constant gas injection or takeoff rate is obtained and investigated. A numerical algorithm for solving the boundary-value problem obtained is proposed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 64–71, November–December, 1991.In conclusion, the author wishes to thank V. M. Maksimov for taking a constant interest in the work and discussing the results.     

On one approach to the investigation of problems with parameters in boundary conditions

We study a rapidly convergent modification of a two-sided method for the approximate integration of a boundary-value problem with parameters in boundary conditions for a system of quasilinear second-order differential equations. __________ Translated from Neliniini Kolyvannya, Vol. 11, No. 3, pp. 348–364, July–September, 2008.     

Study of the plane problem for a physically nonlinear elastic solid by methods of the theory of functions of one complex Variable

Successful application of methods of complex analysis in linear elasticity problems, initiated by Kolosov, Muskhelishvili, Vekua, and their students, serves as a basis for similar studies in the field of analytical-numerical approximations to solutions of boundary value problems and various nonlinear equations of mathematical physics. In the present paper, we suggest a method for solving plane boundary-value problems for a special class of physically nonlinear elastic solids in the case of small strains. This general method, which can be used for a wide class of domains, is illustrated by the example of a square domain with boundary conditions given in stresses. These methods can also easily be used for boundary conditions of other types.     

Gradient elasticity and nonstandard boundary conditions

Gradient elasticity for a second gradient model is addressed within a suitable thermodynamic framework apt to account for nonlocality. The pertinent thermodynamic restrictions upon the gradient constitutive equations are derived, which are shown to include, besides the field (differential) stress–strain laws, a set of nonstandard boundary conditions. Consistently with the latter thermodynamic requirements, a surface layer with membrane stresses is envisioned in the strained body, which together with the above nonstandard boundary conditions make the body constitutively insulated (i.e. no long distance energy flows out of the boundary surface due to nonlocality). The total strain energy is shown to include a bulk and surface strain energy. A minimum total potential energy principle is provided for the related structural boundary-value problem. The Toupin–Mindlin polar-type strain gradient material model is also addressed and compared with the above one, their substantial differences are pointed out, particularly for what regards the constitutive equations and the boundary conditions accompanying the solving displacement equilibrium equations. A gradient one-dimensional bar sample in tension is considered for a few applications of the proposed theory.     

Singular perturbation of second-order nonlinear system with boundary perturbation

Ｗｅｃｏｎｓｉｄｅｒｉｎｔｈｉｓｐａｐｅｒｔｈｅｓｉｎｇｕｌａｒｐｅｒｔｕｒｂａｔｉｏｎｏｆｓｅｃｏｎｄ＿ｏｒｄｅｒｎｏｎｌｉｎｅａｒｓｙｓｔｅｍｉｎｖｏｌｖｉｎｇｉｎｔｅｒｇｒａｌｏｐｅｒａｔｏｒεｙ″=ｆ(ｔ,ｙ,Ｔｙ,ε)ｙ′ ｇ(ｔ,ｙ,Ｔｙ,ε),(1)ｗｉｔｈｂｏｕｎｄａｒｙｐｅｒｔｕｒｂａｔｉｏｎｙ(ｔ,ε)｜ｔ=φ(ε)=α(ε),ｙ(ｔ,ε)｜ｔ=1 ψ(ε)=β(ε),(2)ｗｈｅｒｅε>0ｉｓａｓｍａｌｌｐａｒａｍｅｔｅｒ,ａｎｄφ(ε),ψ(ε)ａｒｅｂｏｔｈ,ｗｉｔｈｒｅｓｐｅｃｔｔｏε,ｓｕｆｆｉｃｉｅｎｔｌｙｓｍｏ…     

A generalized inverse procedure for bifurcation problems

We give a systematic procedure for handling the linear aspects of the investigation of a bifurcation problem for the solutions of a boundary-value problem with ordinary differential equations. The method is an alternative method. The required projections are uniquely specified. We also use the related generalized inverse of the linear mapping.

The technique is illustrated with two examples of periodic solutions of second-order nonlinear differential equations.     

Weakly nonlinear boundary-value problems for differential equations in a Banach space in the critical case

We obtain necessary and sufficient conditions for the existence of solutions of weakly nonlinear boundary-value problems for differential equations in a Banach space. A convergent iterative procedure is proposed for the determination of solutions. We also establish a relationship between necessary and sufficient conditions.     

Regular integral equations for the second boundary-value problem of the bending of an anisotropic elastic plate

Two systems of Fredholm equations of the second kind are constructed for the solution of the second boundary-value problem of the bending of an anisotropic plate (a normal bending moment and a generalized shear force are specified on the boundary of the simply-connected domain) under the assumption of validity of the Kirchhoff-Love hypotheses. Correct equilibrium conditions are specified for the examined boundary-value problem. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 3, pp. 108–119, May–June, 2005.     

Gradient nanoscale polycrystalline elasticity: Intergrain interactions and triple-junction conditions

Using the principle of virtual power, we develop general balance equations, interface conditions, triple-junction conditions, and boundary conditions for second-grade nanocrystalline elastic materials undergoing infinitesimal deformations. We further develop thermodynamically consistent constitutive equations and provide a weak formulation of resulting boundary-value problems that automatically yields internal conditions such those that hold across interfaces and at triple junctions.