Asymptotics of solutions of a system of linear inhomogeneous singularly perturbed differential equations

Solutions with asymptotics in integral and fractional powers of the parameter ? are constructed for the vector differential equation $$\varepsilon ^h \dot X = A(t,\varepsilon ) X + \varepsilon ^{\alpha _1 } p(t,\varepsilon ) \exp \left( {\varepsilon ^{ - h} \int\limits_0^t {\lambda (\tau )d\tau } } \right)$$ in the case of resonance and multiple spectrum of the limit matrix. $$\varepsilon ^h \dot X = A(t,\varepsilon ) X + \varepsilon ^{\alpha _1 } p(t,\varepsilon ) \exp \left( {\varepsilon ^{ - h} \int\limits_0^t {\lambda (\tau )d\tau } } \right)$$      

Asymptotics of regularized solutions of an ill-posed Cauchy problem for an autonomous linear system of differential equations with commensurable delays

We construct an infinite family of hyperbolic three-manifolds with geodesic boundary that generalize the Thurston and Paoluzzi-Zimmermann manifolds. For the manifolds of this family, we present two-sided bounds for their complexity.     

Periodic solutions to nonlinear nonautonomous system of differential equations

We prove a theorem on the existence of nonzero periodic solution to a system of differential equations by the method of fixed point of nonlinear operator defined on a topological product of two compact sets.     

Nontrivial periodic solutions of a nonautonomous system of second-order differential equations

We prove theorem, in which basic conditions for the existence of nontrivial periodic solutions are formulated in terms of the properties of the elements of the matrix of a linear approximation to a system. Ryazan Pedagogical Institute, Ryazan. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 46, No. 6, pp. 754–759, June, 1994.     

Periodic solutions of nonautonomous ordinary differential equations

For higher order ordinary differential equations, new sufficient conditions on the existence and uniqueness of periodic solutions are established. Results obtained cover the case when the right-hand side of the equation is not of a constant sign with respect to an independent variable.     

Uniformly attracting solutions of nonautonomous differential equations

Understanding the structure of attractors is fundamental in nonautonomous stability and bifurcation theory. By means of clarifying theorems and carefully designed examples we highlight the potential complexity of attractors for nonautonomous differential equations that are as close to autonomous equations as possible. We introduce and study bounded uniform attractors and repellors for nonautonomous scalar differential equations, in particular for asymptotically autonomous, polynomial, and periodic equations. Our results suggest that uniformly attracting or repelling solutions are the true analogues of attracting or repelling fixed points of autonomous systems. We provide sharp conditions for the autonomous structure to break up and give way to a bewildering diversity of nonautonomous bifurcations.     

Periodic solutions of nonautonomous ordinary differential equations

For higher order ordinary differential equations, new sufficient conditions on the existence and uniqueness of periodic solutions are established. Results obtained cover the case when the right-hand side of the equation is not of a constant sign with respect to an independent variable.     

Asymptotics of solutions of a singularly perturbed system of differential equations with delay

Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 41, No. 5, pp. 652–658, May, 1989.     

Asymptotics of solutions of a second-order linear differential system with a special right-hand side

Odessa. Translated from Sibirskii Matematicheskii Zhurnal, Vol. 31, No. 2, pp. 89–93, March–April, 1990.     

An asymptotic property of the solutions to second order linear nonautonomous delay differential equations

Second order linear nonautonomous delay differential equations are considered, and a fundamental asymptotic criterion for the solutions is established, by the use of the concept of generalized characteristic equation.     

Construction of polynomial solutions of a system of linear differential equations

Ukrainian Mathematical Journal -     

Dichotomy spectra and Morse decompositions of linear nonautonomous differential equations

Recently, the existence of Morse decompositions for nonautonomous dynamical systems was shown for three different time domains: the past, the future and—in the linear case—the entire time. In this article, notions of exponential dichotomy are discussed with respect to the three time domains. It is shown that an exponential dichotomy gives rise to an attractor-repeller pair in the projective space, which is a building block of a Morse decomposition. Moreover, based on the notions of exponential dichotomy, dichotomy spectra are introduced, and it is proved that the corresponding spectral manifolds lead to Morse decompositions in the projective space.     

On the resolvent of linear nonautonomous partial functional differential equations

We give sufficient conditions for the existence of the resolvent operator for nonautonomous linear partial differential equations with delay, where the highest order derivatives are undelayed. Furthermore we analyse the connection between the resolvent and the solution operator of the homogeneous equation.     

Stability conditions for systems of linear nonautonomous delay differential equations

Systems of linear nonautonomous delay differential equations are considered which are of the form y′_i(t) = ∑_{k = 1}ⁿ ∝₀^T b_ik(t, s) y_k(t − s) dη_ik(s) − c_i(t) y_i(t), where I = 1,…, n. Sufficient conditions are derived for both the asymptotic stability and the instability of the zero solution. The main result is found by a monotone technique using elementary methods only. Moreover, additional criteria are obtained by using the method of Lyapunov functionals.     

Asymptotics with respect to a parameter of solutions of linear functional-differential equations

We study the question of the number of linearly independent solutions of the equationy ⁽ⁿ⁾ (x)+(Fy) (x)+ⁿ y (x)=0,x [0, 1], in which F is a bounded linear operator acting on various normed function spaces. A number of assertions about the asymptotic behavior of these solutions with respect to , tending to infinity are established.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 11, pp. 1460–1469, November, 1990.