Stability estimates for the solutions to inverse extremal problems for the Helmholtz equationJournal of Applied and Industrial Mathematics - Tập 7 - Trang 302-312 - 2013
G. V. Alekseev, A. V. Lobanov
The inverse problems are under study for the Helmholtz equation describing acoustic scattering at a three-dimensional inclusion. Some optimization method reduces these problems to the inverse extremum problems with variable refraction index and boundary source density as controls. We prove that these problems are solvable and derive the optimality systems that describe necessary optimality conditi...... hiện toàn bộ
Vibration viscosimetry and a numerical method for determining gelation dynamicsJournal of Applied and Industrial Mathematics - Tập 10 - Trang 474-481 - 2016
V. M. Galkin, A. V. Bogoslovskii, Yu. S. Volkov
Under consideration are the equations describing the movement of a vibration sensor probe in a viscoelastic medium during. A method is proposed for performing experiments and processing the experimental data for simultaneous determination of viscosity and elasticity. Some test calculations using the model case are presented.
Unsteady Flows of a Maxwell Viscoelastic Fluid near a Critical Point with a Countercurrent at the Initial MomentJournal of Applied and Industrial Mathematics - Tập 16 - Trang 105-115 - 2022
N. P. Moshkin
Two-dimensional unsteady stagnation-point flow of a viscoelastic fluid is studied assuming
that it obeys the upper-convected Maxwell (UCM) model. The solutions of constitutive equations
are found under the assumption that the components of the extra stress tensor are polynomials in
the spatial variable along a rigid wall. The class of solutions for unsteady flows in a
neighbourhood of the front o...... hiện toàn bộ
On the shift of a regulatory signal in models of matrix synthesisJournal of Applied and Industrial Mathematics - Tập 7 - Trang 404-411 - 2013
V. A. Likhoshvai, S. I. Fadeev
The paper deals with the limiting properties of the matrix synthesis models that take into account the phenomenon of branching and an unspecified number of intermediate steps. Numerically, it is shown that with unlimited increase of the number of intermediate steps, there is observed a shift of the control signal along the chain synthesis. Also the shift causes the compression of the control funct...... hiện toàn bộ
Estimates of Characteristics of Localization Methods for Discontinuities of the First Kind of a Noisy FunctionJournal of Applied and Industrial Mathematics - Tập 13 - Trang 1-10 - 2019
A. L. Ageev, T. V. Antonova
This is theoretical study of the ill-posed problem on localization (determination of position) of discontinuities of the first kind of a function of one variable. The exact function x is smooth but has finitely many discontinuities of the first kind. Given some approximate function xδ, ||xδ − x|| L2(ℝ) ≤ δ, and the error level δ, it is required to determine the number of discontinuities and approx...... hiện toàn bộ
A Polynomial 3/5-Approximate Algorithm for the Asymmetric Maximization Version of the 3-PSPJournal of Applied and Industrial Mathematics - Tập 13 - Trang 219-238 - 2019
A. N. Glebov, S. G. Toktokhoeva
We present a first polynomial algorithm with guaranteed approximation ratio for the asymmetric maximization version of the asymmetric 3-Peripatetic Salesman Problem (3-APSP). This problem consists in finding the three edge-disjoint Hamiltonian circuits of maximal total weight in a complete weighted digraph. We prove that the algorithm has guaranteed approximation ratio 3/5 and cubic running-time.