On an integral equation of the problem for an elastic strip with a slit

A new singular integral equation is obtained that describes the elastic equilibrium of a strip with both an inner and an edge slit (crack) and has a considerable advantage over existing equations /1–9/, etc.) from the viewpoint of a numerical realization and clarification of the analytical relationship with an analogous equation for a half-plane. Numerical results are given of a computation of the stress intensity coefficients at the tips of the inner and edge cracks that refine data in the literature.     

Enforced stability of an eigenvalue in the continuous spectrum of a waveguide with an obstacle

Perturbations of an eigenvalue in the continuous spectrum of the Neumann problem for the Laplacian in a strip waveguide with an obstacle symmetric about the midline are studied. Such an eigenvalue is known to be unstable, and an arbitrarily small perturbation can cause it to leave the spectrum to become a complex resonance point. Conditions on the perturbation of the obstacle boundary are found under which the eigenvalue persists in the continuous spectrum. The result is obtained via the asymptotic analysis of an auxiliary object, namely, an augmented scattering matrix.     

Perturbation of an eigenvalue in the continuous spectrum of a waveguide with an asymmetric obstacle

Doklady Mathematics -     

Optimal Trajectory of an Observer Tracking the Motion of an Object Equipped with a Striking Device

Doklady Mathematics - An object t equipped with a high-speed striking device moves along a given trajectory $$\mathcal{T}$$ . The object is tracked by a spatial observer f, which has to hide behind...     

On the motion of an oscillator with a periodically time-varying mass

The stability of the motion of an oscillator with a periodically time-varying mass is under consideration. The key idea is that an adequate change of variables leads to a newtonian equation, where classical stability techniques can be applied: Floquet theory for the linear oscillator, KAM method in the nonlinear case. To illustrate this general idea, first we have generalized the results of [W.T. van Horssen, A.K. Abramian, Hartono, On the free vibrations of an oscillator with a periodically time-varying mass, J. Sound Vibration 298 (2006) 1166–1172] to the forced case; second, for a weakly forced Duffing’s oscillator with variable mass, the stability in the nonlinear sense is proved by showing that the first twist coefficient is not zero.     

On the blow-up of the solution of an equation with a gradient nonlinearity

We continue the study of a nonlinear third-order equation of the Hamilton-Jacobi type. For this equation, we consider an initial-boundary value problem in a bounded domain with smooth boundary and prove the local solvability in the strong generalized sense; in addition, we derive sufficient conditions for the blow-up in finite time and sufficient conditions for the time-global solvability.     

Equations of an effective model of an anisotropic elastic medium with cracks filled with a fluid

For a periodic layered medium in which every period consists of an elastic anisotropic layer and a fluid homogeneous layer, an effective model is derived by averaging. This model describes wave propagation and has two phases. The equations of this model are deduced in the case of the general anisotropy and in some special cases. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 210, 1994, pp. 175–191. Translated by L. A. Molotkov.     

Eigenoscillations of a string with an additional mass

Dedicated to S. L. Sobolev on the occasion of his 80th birthday.     

Series Expansions for the Solution of an Integral-Functional Equation with a Parameter

We continue our considerations in [2] and [3] on a homogeneous integral-functional equation with a parameter a > 1 and derive different series expansions for the solution which simplify in the case a ≥ 2. The terms of these series can be interpreted as polynomial splines.