230 research outputs found
FPT-algorithms for some problems related to integer programming
In this paper, we present FPT-algorithms for special cases of the shortest
lattice vector, integer linear programming, and simplex width computation
problems, when matrices included in the problems' formulations are near square.
The parameter is the maximum absolute value of rank minors of the corresponding
matrices. Additionally, we present FPT-algorithms with respect to the same
parameter for the problems, when the matrices have no singular rank
sub-matrices.Comment: arXiv admin note: text overlap with arXiv:1710.00321 From author:
some minor corrections has been don
Isoperiodic deformations of the acoustic operator and periodic solutions of the Harry Dym equation
We consider the problem of describing the possible spectra of an acoustic
operator with a periodic finite-gap density. We construct flows on the moduli
space of algebraic Riemann surfaces that preserve the periods of the
corresponding operator. By a suitable extension of the phase space, these
equations can be written with quadratic irrationalities.Comment: 15 page
Quantum discrete Dubrovin equations
The discrete equations of motion for the quantum mappings of KdV type are
given in terms of the Sklyanin variables (which are also known as quantum
separated variables). Both temporal (discrete-time) evolutions and spatial
(along the lattice at a constant time-level) evolutions are considered. In the
classical limit, the temporal equations reduce to the (classical) discrete
Dubrovin equations as given in a previous publication. The reconstruction of
the original dynamical variables in terms of the Sklyanin variables is also
achieved.Comment: 25 page
Whittaker-Hill equation and semifinite-gap Schroedinger operators
A periodic one-dimensional Schroedinger operator is called semifinite-gap if
every second gap in its spectrum is eventually closed. We construct explicit
examples of semifinite-gap Schroedinger operators in trigonometric functions by
applying Darboux transformations to the Whittaker-Hill equation. We give a
criterion of the regularity of the corresponding potentials and investigate the
spectral properties of the new operators.Comment: Revised versio
Faddeev eigenfunctions for two-dimensional Schrodinger operators via the Moutard transformation
We demonstrate how the Moutard transformation of two-dimensional Schrodinger
operators acts on the Faddeev eigenfunctions on the zero energy level and
present some explicitly computed examples of such eigenfunctions for smooth
fast decaying potentials of operators with non-trivial kernel and for deformed
potentials which correspond to blowing up solutions of the Novikov-Veselov
equation.Comment: 11 pages, final remarks are adde
Heavy quark potential in lattice QCD at finite temperature
Results of the study of lattice QCD with two flavors of nonperturbatively
improved Wilson fermions at finite temperature are presented. The transition
temperature for m_{\pi}/m_{\rho} \sim 0.8 and lattice spacing a \sim 0.12 fm is
determined. A two-exponent ansatz is successfully applied to describe the heavy
quark potential in the confinement phase.Comment: 3 pages, 1 figure, talk given at the 5th International Conference on
Quark Confinement and the Hadron Spectrum, Gargnano, Italy, 10-14 Sep 200
Sub-nanosecond Pulse Generation from a Two-section Laser-thyristor: Theoretical Analysis
We have developed a theoretical model of a two-section laser-thyristor. It is shown that using a 4 µm weakly doped p-base can increase blocking voltage up to 50 V, which makes it possible to generate 2 ns 10 A current pulses. It is demonstrated that the proposed device utilizes passive Q switching to generate high-power short optical pulses that account for up to 80% of output power. By picking the optimal passive section length, we have achieved optical pulses of ∼30 ps full width at half maximum (FWHM) and ∼100 W peak power.
Keywords: pulsed laser, semiconductor N-p-N-i-P heterostructure, laser-thyristor, dynamic model of pulsed lase
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