On the level density of random band matrices

Translated from Matematicheskie Zametki, Vol. 50, No. 6, pp. 31–42, December, 1991.     

Optimal block length for Basic mode data transmission control procedure

This paper considers two models of BASIC mode data transmission: When we transmit data with length l

1. (1) data are divided into N blocks and each block is transmitted individually

2. (2) data are divided into N sub-blocks and all sub-blocks are transmitted together.

We derive total average transmission data lengths of each model and discuss optimal numbers N* and block length B* which minimize them. In model 1, the length of one block is approximately determined independently of l. It is shown in a numerical example that when l is large, model 2 is better than model 1.     

Interaction between large and small signals in a resonant transmission line based on magnetostatic waves

The influence of a large signal on the characteristics of a small signal near the frequency of the former is experimentally studied for the case of their simultaneous propagation through a resonant transmission line based on backward volume magnetostatic waves. The effects observed are caused by the excitation of spin waves in a ferromagnetic film at different large-signal frequencies and by the back influence of excited spin-wave packets on the amplitude and phase characteristics of the small signal.     

Entanglement of qutrits

For two types of qutrits specified by the dynamical symmetry SU(3) and SU(2), we consider the difference in entanglement caused by the lack of quantum observables in the latter case. In particular, we show that the SU(2) qutrits can have specific separable entanglement caused by quantum correlations of intrinsic degrees of freedom in a single party without interparty correlations.     

Ordering of structural vacancies in vanadium monoxide of substoichiometric composition

The order-disorder phase transition in vanadium monoxide of substoichiometric compositions VO_y has been studied for the first time in situ by the Faraday method with a pendulum magnetic balance of the Domenically type. A minimum is found on the temperature dependence of the magnetic susceptibility of vanadium monoxide of different compositions at a temperature of about 700 K. X-ray diffraction analysis performed before and after measuring the magnetic susceptibility confirmed the change in the structure of vanadium monoxide and the possibility of atom-vacancy processes upon cooling and heating of the samples.     

Areal objects and the problem of the λ term in the theory of gravitation

The following areal objects are considered: an ether thread contracting two material points and a multidimensional ether fibre in the pseudo-Euclidean world of events. An ether space-time model with an arbitrarily determined Riemannian metric is constructed and the problem of the λ term in Einstein equations is discussed in this regard.     

Solution of the hyperbolic mild‐slope equation using the finite volume method

A finite volume solver for the 2D depth‐integrated harmonic hyperbolic formulation of the mild‐slope equation for wave propagation is presented and discussed. The solver is implemented on unstructured triangular meshes and the solution methodology is based upon a Godunov‐type second‐order finite volume scheme, whereby the numerical fluxes are computed using Roe's flux function. The eigensystem of the mild‐slope equations is derived and used for the construction of Roe's matrix. A formulation that updates the unknown variables in time implicitly is presented, which produces a more accurate and reliable scheme than hitherto available. Boundary conditions for different types of boundaries are also derived. The agreement of the computed results with analytical results for a range of wave propagation/transformation problems is very good, and the model is found to be virtually paraxiality‐free. Copyright © 2003 John Wiley & Sons, Ltd.     

A pulsed ion-ion recombination laser

A new mechanism of pulsed laser oscillation based on ion-ion recombination is proposed. The advantages of utilizing this mechanism in a pulsed mode are considered, and the expected characteristics of the proposed lasers are estimated.