Not only sagas: The Early History of Norway in medieval Monuments.

The interest towards sources on early Norwegian history is traditional for Russia, and Russian specialists on Viking and Medieval Norway, such as Mikhail Steblin-Kamensky, Aron Gurevich, Elena Mel’nikova and Tatyana Dzhakson are known both in Russia and abroad. However, these scholars have mainly focused on the sagas. As a result, Norwegian chronicles are less familiar to the Russian audience. The anthology “Not only sagas…” fills this gap

Splitting time for irrational triangle billiards

We find an upper estimate for a splitting time of a thin parallel beam for irrational triangle billiards in terms of some number-theoretic function of angles. We provide an upper estimate on this function for some class of angles.Comment: 6 figure

On the sign definiteness of Liapunov functionals and stability of a linear delay equation

In this paper we give a new definition of the positive-definiteness of the Liapunov functional involved in the stability and asymptotic stability investigation. Using this notion we prove Liapunov type theorems and apply these results to the scalar equation $\dot x(t)=b(t)x(t-r(t))$, where $b(t)$ and $r(t)$ may be unbounded

Difficulties in implementation of viscosity models in the fragmenton-based vortex methods

Fragmenton-based lagrangian vortex methods showed their effectiveness for inviscid fluid dynamics problems. However the attempts to extend these methods to viscous flows simulation meet difficulties resulting from nonfulfillment of the Helmholtz theorems of vorticity motion. Direct implementation of the viscosity models used in particle-based vortex methods leads to fragmenton ”splitting” problem and accumulation of numerical errors. In this paper we discuss in details the essence of splitting problem on the examples of a classical Particle Strength Exchange (PSE) method and a hybrid DVM-PSE scheme, adapted to a fragmenton-based vortex method