Effect of residual gas on the dynamics of water adsorption under isobaric stages of adsorption heat pumps: Mathematical modelling

A mathematical model of the coupled heat and mass transfer in an adsorbent layer was developed to study the effect of a non-adsorbable gas (air, hydrogen) on kinetics of water adsorption on loose grains of the composite adsorbent SWS-1L (silica modified by calcium chloride). The adsorbent monolayer was placed on the surface of an isothermal metal plate at T = 60 °C and equilibrated with the mixture of water vapor at constant P = 10.3 mbar in the presence of the non-adsorbable gas at a variable partial pressure P_A = 0.06–14.3 mbar. After that the metal plate is subjected to a temperature drop down to 35 °C that initiates water adsorption. It is shown that the adsorption of water causes effective gas sweeping to the surface where it was accumulated as a gas-rich layer. This results in dramatic slowing down of the adsorption and heat transfer processes.     

Action of a gas flux on the surface layer of the bore

The heating parameters and temperature of the surface layer in the bore are determined in the case of a single shot, for sections of the bore subject to the action of a gas flux at the corners of grooves that are unfilled by the bullet’s casing.     

Motion of a spherical cloud of bubbles in a liquid with motionless packing

On the basis of Darcy's linear law of resistance, the problem of the ascent of a spherical cloud of bubbles in an infinite liquid with a motionless solid phase is solved. The influence of inertia of the liquid on the character of cloud deformation is discussed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 46, No. 4, pp. 600–605, April, 1984.     

On Curvatures and Focal Points of Distributions of Dynamical Lagrangian Distributions and their Reductions by First Integrals

Pairs (Hamiltonian system, Lagrangian distribution) called dynamical Lagrangian distributions, appear naturally in differential geometry, calculus of variations, and rational mechanics. The basic differential invariants of a dynamical Lagrangian distribution with respect to the action of the group of symplectomorphisms of the ambient symplectic manifold are the curvature operator and curvature form. These invariants can be considered as generalizations of the classical curvature tensor in Riemannian geometry. In particular, in terms of these invariants one can localize the focal points along extremals of the corresponding variational problems. In the present paper we study the behavior of the curvature operator, the curvature form, and the focal points of a dynamical Lagrangian distribution after its reduction by arbitrary first integrals in involution. An interesting phenomenon is that the curvature form of so-called monotone increasing Lagrangian dynamical distributions, which appear naturally in mechanical systems, does not decrease after reduction. It also turns out that the set of focal points to the given point with respect to the monotone increasing dynamical Lagrangian distribution and the corresponding set of focal points with respect to its reduction by one integral are alternating sets on the corresponding integral curve of the Hamiltonian system of the considered dynamical distributions. Moreover, the first focal point corresponding to the reduced Lagrangian distribution comes before any focal point related to the original dynamical distribution. We illustrate our results on the classical N-body problem. 2000 Mathematics Subject Classification. 37J15, 37J05, 53D20.     

Technology of Monitoring and Analysis of the Hydrometeorological Situation in the Arctic

Journal of Communications Technology and Electronics - A new geoinformation technology for monitoring the hydrometeorological situation in the Arctic is considered. This technology combines two...     

Fundamental Form and the Cartan Tensor of (2,5)-Distributions Coincide

In our previous paper, for a generic rank-2 vector distributions on an n-dimensional manifold (n ≥ 5) we constructed a special differential invariant, the fundamental form. In the case n = 5, this differential invariant has the same algebraic nature, as the covariant binary biquadratic form, constructed by E. Cartan, using his “reduction-prolongation” procedure (we call this form the Cartan tensor). In the present paper, we prove that our fundamental form coincides (up to the constant factor −35) with the Cartan tensor. This result explains geometrically the reason for the existence of the Cartan tensor (originally, this tensor was obtained by very sophisticated algebraic manipulations) and gives the true analogs of this tensor in the Riemannian geometry. In addition, as a part of the proof, we obtain a new useful formula for the Cartan tensor in terms of the structural functions of any frame naturally adapted to the distribution. 2000 Mathematics Subject Classification. 58A30, 53A55.     

Correlation between the wearing process of a sniper rifle barrel and bullet structure

The correlation between the diametral wear of a small arms barrel and the bullet structure of a sniper cartridge is presented. For a monolithic bullet, it is possible to separate two typical segments of barrel wear, and for a full-jacketed bullet there are three segments. These phenomena are explained in terms of physical laws.     

Mathematical modeling of the drying stage of a composite adsorbent in a solar composite refrigerator

This article deals with the mathematical model of the drying stage of composite water adsorbents of the type featuring calcium chloride impregnated into silica gel matrix pores. The source of heat is solar radiation. Taking into account the specific character of the universal water adsorption curve on this adsorbent, conditions for the generation of the drying front are formulated and the equation of its movement in the adsorbent layer is deduced. The estimated times of drying for adsorbent beds of a different width and at different environment temperatures are compared; two means of the organization of the drying stage are formulated.     

Low-grade heat recovering gas adsorption plant for large-scale refrigerators

A low-grade heat recovery system for large-scale refrigerators is proposed. The system comprises an evaporation refrigeration cycle with an inert carrier gas and a thermal adsorption-desorption cycle for adsorption drying of a gas flow. The known low-grade heat recovery systems using adsorption heat pumps with closed vapor-phase cycles for refrigeration are inefficient because of the rather low partial vapor pressure of the working medium. Moreover, such systems are highly sensitive to an unsorbable component, which is inevitably accumulated in the vapor phase. The system proposed is free of these drawbacks, since the unsorbable component is used as a working-medium vapor carrier, thus enhancing the mass-transfer processes.     

Use of the Method of Acoustic Emission for Studying the Laws of Formation of Secondary Structures at Friction of Nicotrated Steels

The processes of structure formation on the surface of nicotrated steel 30KhN2MFA at friction under the conditions of life lubrication of a “brad – disk” couple are studied in a special installation, which makes it possible to continuously measure the force of friction, the temperature in the contact zone, and the signals of acoustic emission during the test. The structures formed on the surface of nicotrated steel during friction are analyzed qualitatively and quantitatively with the help of a local friction factor f _loc that characterizes friction on individual local areas. A comparative analysis of temperature dependences of the parameter f _loc and of the phase composition of the dissipative layer (“third body”) formed on the surface of the carbonitride layer during friction is performed. An empirical equation relating these two characteristics is suggested.