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Vol 63, No 1 (2018)
- Year: 2018
- Articles: 10
- URL: https://journals.rcsi.science/1028-3358/issue/view/12095
Physics
Effect of Long-Period Ordering of the Structure of a Plant on the Initial Stages of Photosynthesis
Abstract
Using data on the structure of plant leaves, specific features of light propagation in biophotoniccrystal structures have been established by the transfer matrix method. Splitting of the stopband in two bands has been found. The density of photonic states and the electromagnetic field value have been calculated. The occurrence of two photosystems (splitting of the stopband in two bands), the peculiarity of the long-wavelength quantum yield and its enhancement (Emerson effect), and water dissociation in the soft mode due to an increase in the electromagnetic field on the layers are explained.
1-4
5-7
Technical Physics
Damage to a Multilayer Woven Composite by Low-Velocity Indentation with a Rigid Spherical Indenter
Abstract
The results of experimental studies of damage to a layer of a woven composite by pressing steel spherical indenters are presented. The effect of the indenter-curvature radius on the structure of the localdamage area of the composite and the effect of the local damage on the strength of initially equistrength composites under tension along the principal directions of layer reinforcement are determined.
8-12
Mechanics
Optimal Damping of Perturbations of Moving Thermoelastic Panel
Abstract
The translational motion of a thermoelastic web subject to transverse vibrations caused by initial perturbations is considered. It is assumed that a web moving with a constant translational velocity is described by the model of a thermoelastic panel simply supported at its ends. The problem of optimal damping of vibrations when applying active transverse actions is formulated. For solving the optimization problem, modern methods developed in control theory for systems with distributed parameters described by partial differential equations are used.
13-17
Approximated Analytical Solution of a Problem on Indentation of an Electro-Elastic Half-Space with Inhomogeneous Coating by a Conductive Punch
Abstract
The paper addresses to the development of the bilateral asymptotic method of solution of contact problems taking into account electro-mechanical fields coupling. Approximated analytical solutions are provided for contact problems on indentation of an electroelastic piezoelectric half-space with inhomogeneous in depth piezoelectric coating by a rigid conductive circular flat, spherical or conical punch.
18-22
An Efficient Model for Layer-by-Layer Analysis of Sandwich Irregular Cylindrical Shells of Revolution
Abstract
Based on the approach of layer-by-layer analysis, we consider an algorithm for constructing finiteelement models of layers for a refined calculation of the stress-strain state of sandwich cylindrical shells with the application of efficient approximations that increase the rate of convergence of the numerical results and, consequently, allow the order of the systems of equations to be reduced, which is particularly topical in the layer-bylayer analysis of laminated inhomogeneous constructions. An example of applying the models considered to calculate the stress-strain state of a sandwich cylindrical shell with through and non-through cuts is given.
23-27
Electrohydrodynamics of Bipolar Membranes
Abstract
On the basis of the Nernst−Planck−Poisson−Stokes system, the behavior of the electrolyte solution is numerically studied for the first time in bipolar electrical membranes under the action of an external electric field while taking into account water dissociation.
28-32
Justification of Shallow-Water Theory
Abstract
The basic conservation laws of shallow-water theory are derived from multidimensional mass and momentum integral conservation laws describing the plane-parallel flow of an ideal incompressible fluid above the horizontal bottom. This conclusion is based on the concept of hydrostatic approximation, which generalizes the concept of long-wavelength approximation and is used for justifying the applicability of the shallow-water theory in the simulation of wave flows of fluid with hydraulic bores.
33-37
Application of Fermat’s Principle to Calculation of the Errors of Acoustic Flow-Rate Measurements for a Three-Dimensional Fluid Flow or Gas
Abstract
Fermat’s variational principle is used for derivation of the formula for the time of propagation of a sonic signal between two set points A and B in a steady three-dimensional flow of a fluid or gas. It is shown that the fluid flow changes the time of signal reception by a value proportional to the flow rate independently of the velocity profile. The time difference in the reception of the signals from point B to point A and vice versa is proportional with a high accuracy to the flow rate. It is shown that the relative error of the formula does not exceed the square of the largest Mach number. This makes it possible to measure the flow rate of a fluid or gas with an arbitrary steady subsonic velocity field.
38-42
Erratum
Erratum to: “New Invariant Relations for One Critical Subsystem of a Generalized Two-Field Gyrostat”
43-43