On the Use of Indium Arsenide as the Waveguide Material in the Measurements by Attenuated Total Reflectance

Optics and Spectroscopy - The current–voltage characteristics and photocurrent of “monolithic” diode optical pairs optically coupled by a substrate made of InAs common for them...     

Midinfrared Light-Emitting Diodes Based on А3В5 Heterostructures in Gas-Analyzer-Equipment Engineering: Potential and Applications in 2014–2018

Optics and Spectroscopy - Studies published in the period from 2014 to 2018 that are aimed at creating nondispersive and photoacoustic IR gas analyzers with LED radiation sources based on...     

Locally 2-fold symmetric manifolds are locally symmetric

A manifold is locally k-fold symmetric if for any point and any k-dimensional vector subspace tangent to this point, there exists a local isometry such that this point is a fixed point and the differential of the isometry restricted to that k-dimensional vector subspace is minus the identity. We show that for \(k \ge 2\), Riemannian, pseudoriemannian, and Finslerian locally k-fold symmetric manifolds are locally symmetric.     

Multigrid Models of Composite Materials of Irregular Structure with a Small Filling Ratio

This paper considers composites consisting of a set of typical composite multigrid finite elements whose structures are regular and different. Mean local errors are proposed for multigrid modeling of composites.     

Reconstruction of the blood flow velocity vector as an additional mode of ultrasonic tomograph

The possibility of simultaneous reconstruction of the blood flow velocity vector and spatial distributions of the speed of sound and absorption coefficient in a medical ultrasonic tomograph is discussed. The operating capacity of the proposed spatial-correlation method for determining the blood flow velocity vector is confirmed by experiments on a tomograph prototype.     

Study of the reaction π–<Emphasis Type="Italic">A</Emphasis> π<Superscript>+</Superscript>π<Superscript>–</Superscript>π<Superscript>–</Superscript><Emphasis Type="Italic">A</Emphasis> at large statistics with VES setup

Partial wave analysis of the π–A π⁺π^–π^– system produced by 29 GeV/cπ^– beam on a beryllium target is presented. About 30 × 10⁶ |events in the wide t′|range 0–0.8 GeV²/c ² are collected with upgraded VES setup. The size of the data sample is 2.5 times larger than one previously analyzed by VES. Data are analyzed using formalism of the density matrix with unlimited rank. We discuss status of the a ₁(1420) a ₂(1700) a ₃(1875) states and a structure of exotic ρ(770)π P-wave with J ^PC = 1^-+. Parameters of a ₃(1875) are estimated as M = 1985 ± 20 MeV/c ², Γ = 200 ± 50 MeV/c ² (preliminary).     

Model of a gas of solid particles with allowance for inelastic collisions

A study is made of the structure of the interaction region of a flow of solid particles with a surface (or another flow) in the case when the width of this region is much greater than the mean free path of the particles between collisions. The disperse phase is described by means of a model of an ideal non-heat-conducting gas of imperfectly elastic spherical particles. For simplicity, the influence of the carrier medium on the motion of the particles is ignored.     

Seepage from shallow channels and irrigation furrows

Two cases of two-dimensional steady seepage from broad channels and irrigation furrows through a layer of homogeneous isotropic soil into a highly permeable pressurized aquifer in the presence of soil capillarity are examined in the hydrodynamic formulation. A uniform method of solution in which the solution of the problem of seepage from an irrigation furrow can be obtained from the solution for a broad channel is given. The special and limiting cases studied in [1–3] and elsewhere are noted. Computer calculations are used to analyze the dependence of the rate of seepage from channels and irrigation furrows and the capillary spread on the profile and width of the channel or irrigation furrow, the thickness of the layer, the head and the capillarity of the soil.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 96–102, January–February, 1989.The authors are grateful to N. N. Verigin for valuable comments.