Influence of the Fermi-liquid interaction of free-carriers on the form of absorption edge in semiconductors

Conditions for existence of the Fermi-liquid interaction of free-carriers may be realized in highly doped semiconductors. This interaction causes the change of the density of states of electron gas close to the Fermi surface. It is possible to detect this change of the density of states using the absorption spectra of the degenerated semiconductors. It is shown that the absorption spectra of the compounds Pb_0.81Sn_0.19Te at the temperatures close to the helium temperature may be described with allowance for the Fermi-liquid interaction of free-carriers.     

Almost-geodesic mappings of affinely connected and Riemann spaces

Tensor methods are used to present the fundamental facts of the theory of geodesic mappings of affinely connected spaces with and without torsion.Translated from Itogi Nauki i Tekhniki, Seriya Problemy Geometrii, Vol. 13, pp. 3–26, 1982.     

Statistical characteristics of the mechanical properties of glass-reinforced plastics

A statistical analysis has been made of experimental data on the mechanical properties of a glass-reinforced plastic based on T₁ glass fabric (Soviet standard GOST 8481-61) and IF-ÉD-6 epoxy resin (Elektroizolit Plant, tech. spec. TU 26-59) obtained by testing specimens cut from the waste of wound cylindrical shells. The data obtained can be used for estimating the mechanical reliability of products composed of glass-reinforced plastics of this type.Moscow. Translated from Mekhanika Polimerov, No. 1, pp. 131–134, January–February, 1971.     

Qualitative properties of modified equations

Suppose that a consistent one-step numerical method of orderr is applied to a smooth system of ordinary differential equations.Given any integer m 1, the method may be shown to be of orderr + m as an approximation to a certain modified equation. Ifthe method and the system have a particular qualitative propertythen it is important to determine whether the modified equationsinherit this property. In this article, a technique is introducedfor proving that the modified equations inherit qualitativeproperties from the method and the underlying system. The techniqueuses a straightforward contradiction argument applicable toarbitrary one-step methods and does not rely on the detailedstructure of associated power series expansions. Hence the conclusionsapply, but are not restricted, to the case of Runge-Kutte methods.The new approach unifies and extends results of this type thathave been derived by other means: results are presented forintegral preservation, reversibility, inheritance of fixed points.Hamiltonian problems and volume preservation. The techniquealso applies when the system has an integral that the methodpreserves not exactly, but to order greater than r. Finally,a negative result is obtained by considering a gradient systemand gradient numerical method possessing a global property thatis not shared by the associated modified equations.     

How Fast can a Subharmonic Function Decay Along a Ray?

Much is known about the connection between the growth and decayof subharmonic functions. The results indicate that there isa general principle: asubharmonic function cannot decay ‘toofast’ relative to its growth.Three theorems are provedwhich, together with work previously published elsewhere, givea fairly complete account of how this principle works out fora subharmonic function having extremal decay along a ray. 1991Mathematics Subject Classification: 30D20, 31A05.     

ARTIFICIAL NEURAL NETWORK ANALYSIS IN INTERFEROMETRIC THz IMAGING FOR DETECTION OF LETHAL AGENTS

In the context of a non-invasive, non-contact method to detect concealed lethal agents employing stand-off imaging in the Terahertz (THz) range using an interferometric detector array, the techniques of image analysis are discussed. To complement the experimental testing, extensive modeling simulates reconstructed images of lethal agents at different THz frequencies applying interferometric techniques. The composite images are consequently analyzed using artificial neural network to make positive identification of the lethal agent. This work also attempts to address issues related to the presence of barriers and isolate some suitable numerical techniques required for rapid and successful recognition of lethal agents during security screening in THz range.     

Establishing the law of distribution of load-carrying capacity of fiberglass-reinforced plastic tubes

The problem of determining the parameters of the law of distribution of load-carrying capacity of fiberglass-reinforced plastic tubes, obtained by the method of winding impregnated cloth on a mandrel, has been dealt with. The parameters of the law of distribution of the load-carrying capacity are determined by the statistical model analysis of the problem with the help of a computer, applying the unified strength criterion of Gol'denblat—Kopnov and on the basis of the results of breaking and control tests along with the use of the method of graphical analysis of the risk function of distribution of the load-carrying capacity.