Two-point boundary value problem for a singularly perturbed ordinary differential equation of second order is considered in the case when the degenerate equation has three unintersecting roots from which one root is two-tuple and two roots are one-tuple. It is prooved that for sufficiently small values of the small parameter the problem has a solution with the transition from the two-tuple root of the degenerate equation to the one-tuple root in the neighbourhood of an internal point of the interval. The asymptotic expansion of this solution is constructed. It distinguishes from the known expansion in the case when all roots of the degenerate equation are one-tuple, in particular, the transitional layer is multizonal.

The method of the logistic function is presented for finding exact solutions of nonlinear differential equations. The application of the method is illustrated by using the nonlinear ordinary differential equation of the fourth order. Analytical solutions obtained by this method are presented. These solutions are expressed via exponential functions.

logistic function, nonlinear wave, nonlinear ordinary differential equation, Painlev´e test, exact solution

The feasibility of a known blue-sky bifurcation in a class of three-dimensional singularly perturbed systems of ordinary differential equations with one fast and two slow variables is studied. A characteristic property of the considered systems is that they permit so-called nonclassic relaxation oscillations, that is, oscillations with slow components asymptotically close to time-discontinuous functions and a δ-like fast component. Cases when blue-sky bifurcation leads to a relaxation cycle or stable two-dimensional torus are analyzed. Also the question of homoclinic structure emergence is considered.

We study local dynamics of a nonlinear second order differential equation with a large exponentially distributed delay in the vicinity of the zero solution under the condition γ>√ 2. The parameter γ can be interpreted as a friction coefficient. We find such parameter values that critical cases in the stability problem are realized. We show that the characteristic equation for zero solution stability can have arbitrary many roots in the vicinity of imaginary axis. So, the critical case of an infinite dimension is realized. We construct normal forms analogues to describe dynamics of the origin equation. We formulate results about the correspondence of solutions of received PDE and second order DDE with a large exponentially distributed delay. The received asymptotic formulas allow us to evidently find characteristics of origin problem local regimes that are close to the zero solution and also to obtain domains of parameters and initial conditions, where the appearance of any given-type solution is possible.

The location of zeros of two characteristic quasi-polynomials arising from studying the differential equations with a retarded argument is considired. The first one originates from the mathematical model of electromagnetic oscillations generator with a delayed feedback, the second one — from the Lang-Kobayashi system that is a well-known mathematical model of a quantum generator. The D-partition figures are presented in a prameter space and possible critical cases are found out. The large delay case important for applications is considered. In this case, for quasi-polinomial roots obtained are the analytical dependencies on a value reciprocal to the delay, and uniform asymptotical formulas are constructed.

This paper is devoted to the construction of a zero-order approximation of the solution of a three-time scale singular perturbed linear-quadratic optimal control problem with the help of the direct scheme method. The algorithm of the method consists in immediate substituting a postulated asymptotic expansion of solution into the problem condition and constructing a family of control problems to define the terms of the asymptotic expansion. Asymptotic approximation of the solution contains regular functions and four boundary ones of exponential type which are determined from the five linearquadratic optimal control problems. It is shown, that the system of equations for a zero-order approximation appeared from control optimality conditions of the initial perturbed problem corresponds to control optimality conditions appeared in respective five optimal control problems constructed for finding zero-order asymptotic approximation with the help of the direct scheme method. An illustrative example is given.

In the present work, we study the features of dissipative structures formation described by the periodic boundary value problem for the Kuramoto-Sivashinsky equation. The numerical algorithm which is based on the pseudospectral method is presented. We prove the efficiency and accuracy of the proposed numerical method on the exact solution of the equation considered. Using this approach, we performed the numerical simulation of dissipative structure formations described by the Kuramoto–Sivashinsky equation. The influence of the problem parameters on these processes are studied. The quantitative and qualitative characteristics of dissipative structure formations are described. We have shown that there is a value of the control parameter at which the processes of dissipative structure formation are observed. In particular, using the cyclic convolution we define the average value of this parameter. Also, we find the dependence of the amplitude of the structures on the value of control parameter.

In the paper we focus on the experience of some Networked Readness Index (NRI) leading countries. We are interested in their actions aimed at creating and using e-infrastructures and IT for the research data aggregation. As far as quite many of NRI leaders are EU countries, we also take into account EU approaches to the task mentioned. We study some steering papers and some particular IT-projects in the field as well. As a result of the analysis we ascertain that some approaches in different countries have much in common. All of the countries examined acknowledge the problem of e-infrastructures for research data storage and processing to be vital. The countries work hard in order to build and integrate it with the others. We can clearly see some differences caused by traditions and authorities. Sometimes we even could estimate the level of success of a particular country on the way to the problem solution. We also indicate some common elements for all e-infrastructures for research data storage and processing.

The sharp Jackson–Stechkin inequalities are received, in which a special module of continuity Ωe_m(f;t) determined by Steklov’s function is used instead the usual modulus of continuity of mth order ω_m(f;t). Such generalized modulus of continuity of mth order were introduced by V.A. Abilov and F.V. Abilova. The introduced modulus of continuity found their application in the theory of polynomial approximation in Hilbert space in the works by M.Sh. Shabozov and G.A. Yusupov, S.B. Vakarchuk and V.I. Zabutnaya and others. While continuing and developing these direction for some classes of functions defined by modulus of continuity, the new values of n-widths in the Hilbert space L₂were found.