Synchronization of gas-laser modes during modulation of the dielectric constant of the medium

In a calculation of the regions in which the modes of a gas laser are synchronized during modulation of the dielectric constant of the laser medium, two synchronization regions are found. The synchronization band in one of them is much higher than that in the other. The calculated results are confirmed experimentally, and it is shown that when the modes are synchronized the fluctuations in the radiation intensity are 20–30 dB below their level in the absence of synchronization.Translated from Izvestiya VUZ. Fizika, No. 8, pp. 17–22, August, 1970.     

Boundary-condition transformation in problems of electromagnetic-wave scattering by an uneven impedance surface

A rigorous method is developed for transforming a boundary-value problem of electrodynamics in a domain with an uneven boundary to an equivalent problem in a domain with a boundary of a new form. The resulting problem is reduced to an integral boundary equation. This equation is solved by expansion into a series in powers of a small parameter, which is determined by the height of the irregularities in the case of a rough boundary. Impedance corrections for roughness-both determinate and randomare found for an underlying surface of arbitrary form in an inhomogeneous medium.Kharkov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 36, No. 3-–, pp. 240–257, March–April, 1993.     

Synchronization of a self-excited oscillator with a biharmonic external signal

The effect of a weak external signal on the change in the limits of the harmonic synchronization band is studied. The regions of synchronization at combination frequencies are found.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 58–63, May, 1988.     

Influence of coupling parameters on the nonlinear dynamics of two cascade-coupled phase-locked loops

We investigate the regimes of synchronization and the causes of its disturbance in a system of two series-connected generators with local phase-control feedback loops. Primary attention is given to analyzing the influence of couplings on collective dynamics of the system.Institute of Applied Mathematics and Cybernetics, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, Nos. 3–4, pp. 275–279, March–April, 1995.     

Volume and grain boundary diffusion of implanted 113Sn in aluminium

Volume and grain boundary diffusion of ¹¹³Sn in aluminium was investigated with the radiotracer method. The implantation technique was used for tracer deposition to avoid problems of tracer hold-up caused by the oxide layer always present on aluminium. The diffusion penetration was chosen large enough to permit serial sectioning of samples with the aid of a microtome.The temperature dependence of the volume diffusivity was determined as D(T)=4.54×10^–5×exp[–(114.5±1.2)kJmol^–1/RT] m ² s ^–1. This confirms previous measurements from our group which already showed that Sn is the fastest foreign metal diffusor so far investigated in aluminium.Grain boundary diffusion of ¹¹³Sn in Al polycrystals was measured in the type-B kinetic regime. The grain boundary diffusion product P=sD _gb (s=segregation factor, =grain boundary width, D _gb=grain boundary diffusivity) was found to be strongly affected by the impurity content of aluminium. For Al polycrystals of 99.9992% nominal purity we obtained P _5N(T)=1.08×10^–8exp [–(96.9±7.5) kJ mol^–1/RT] m³ s^–1 and for less pure Al polycrystals of 99.99% nominal purity P _4N(T)=3.0×10^–10 exp [–(90.1±4.2) kJ mol^–1/RT] m³ s^–1 was determined. The grain boundary diffusion product in the purer material is more than one order of magnitude higher than in the less pure material. Very likely this is an effect of co-segregation of non-diffusant impurities into the grain boundaries.     

Experimental robust synchronization of hyperchaotic circuits

Even if complete synchronization between two chaotic circuits can be reached only when the systems are identical, in this paper we address the robustness of synchronization in the presence of parameter mismatches between the coupled circuits in the case of hyperchaotic behavior. In particular, a master–slave scheme based on negative feedback [T. Kapitaniak, Synchronization of chaos using continuous control, Phys. Rev. E 50 (1994) 1642–1644] is considered and the strategy to design the slave system as an observer of the master is given. With the proposed approach, based on the concept of the Master Stability Function, the two circuits are coupled through a unique scalar signal. Experimental results obtained from two hyperchaotic circuits will be presented in order to show that synchronization occurs widely in the range of electronic component tolerances.     

A diffusion problem in a region with a moving boundary

We consider the first linear diffusion problem in a semiinfinite region with a boundary moving in accordance with a quadratic law. For the case of uniformly decelerating motion of the boundary, the solution of the problem is obtained by the Green's function, method under the most general boundary conditions; the solution of the problem for the case of uniformly accelerated motion of the boundary is obtained by an operator method.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 102–110, December, 1970.     

Effect of lumped interference on a synchronized generator

Transients in a self-oscillator under biharmonic action are examined on the basis of an auto-parametric model of the synchronization phenomenon. It is shown that an external weak harmonic signal will influence the synchronization mode differently depending on the magnitude and detuning of the synchronizing emf.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 32–37, November, 1981.     

Vacuum quantum effect for curved boundaries in static Robertson–Walker space–time

The energy–momentum tensor for a massless conformally coupled scalar field in the region between two curved boundaries in k=−1 static Robertson–Walker space–time is investigated. We assume that the scalar field satisfies the Dirichlet boundary condition on the boundaries. k=−1 Robertson–Walker space is conformally related to the Rindler space, as a result we can obtain vacuum expectation values of energy–momentum tensor for conformally invariant field in Robertson–Walker space from the corresponding Rindler counterpart by the conformal transformation.     

A test theory of special relativity: I. Simultaneity and clock synchronization

The role of convention in various definitions of clock synchronization and simultaneity is investigated. We show that two principal methods of synchronization can be considered: system internal and system external synchronization. Synchronization by the Einstein procedure and by slow clock transport turn out to be equivalent if and only if the time dilatation factor is given by the Einstein result (1–v ²)^1/2. An ether theory is constructed that maintains absolute simultaneity and is kinematically equivalent to special relativity.     

The parametric nature of the synchronization of a self-exciting oscillator with a nonlinear capacitor

The paper considers the nonautonomous operation of a self-excited valve oscillator with a nonlinear tuned circuit. The nature and mechanism of synchronization from small-amplitude external voltages is explained.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 109–115, May, 1972.     

Generation of Turbulent Inflow Data for Spatially-Developing Boundary Layer Simulations

A method for generating three-dimensional, time-dependent turbulent inflow data for simulations of complex spatially developing boundary layers is described. The approach is to extract instantaneous planes of velocity data from an auxiliary simulation of a zero pressure gradient boundary layer. The auxiliary simulation is also spatially developing, but generates its own inflow conditions through a sequence of operations where the velocity field at a downstream station is rescaled and re-introduced at the inlet. This procedure is essentially a variant of the Spalart method, optimized so that an existing inflow–outflow code can be converted to an inflow-generation device through the addition of one simple subroutine. The proposed method is shown to produce a realistic turbulent boundary layer which yields statistics that are in good agreement with both experimental data and results from direct simulations. The method is used to provide inflow conditions for a large eddy simulation (LES) of a spatially evolving boundary layer spanning a momentum thickness Reynolds number interval of 1530–2150. The results from the LES calculation are compared with those from other simulations that make use of more approximate inflow conditions. When compared with the approximate inflow generation techniques, the proposed method is shown to be highly accurate, with little or no adjustment of the solution near the inlet boundary. In contrast, the other methods surveyed produce a transient near the inlet that persists several boundary layer thicknesses downstream. Lack of a transient when using the proposed method is significant since the adverse effects of inflow errors are typically minimized through a costly upstream elongation of the mesh. Extension of the method for non-zero pressure gradients is also discussed.     

Measurement of transverse vibrations/visualization of mode shapes in square plate by using digital speckle pattern interferometry and wavelet transform

New filtering scheme is investigated and implemented on digital speckle pattern interferometric fringes to enhance the signal-to-noise ratio (SNR) in the speckle interferograms. To establish the potential of new filtering scheme the experiment was conducted on the vibrating cantilever beam. Experimental results revealed that the new filtering scheme is more powerful than other known filtering schemes (Kumar et al. Opt Laser Eng 2004;41:81–93. Kumar et al. Opt Laser Technol 2001;33:567–571. Shakher et al. Opt Eng 2002;41:176–180. Shakher et al. Proceedings ICICS, Singapore, 9–12 September 1997, p. 953–956. Bowler et al. Proceedings of IEE second international conference on image processing, London, 1986, p. 24–26. Lim. Opt Eng 1981;20:670–678. Devila et al. J Mod Opt 1995;42:1795–1804; Kaufmann et al. Opt Eng 1996;35:9–14). The new scheme reduced the speckle noise and improved SNR in speckle interferograms. Further, the new investigated filtering scheme is implemented to study the mode shapes of square plates under two different boundary conditions. In the first condition all the edges of the square plate were fixed while in the second condition two adjacent edges were fixed and the remaining two edges were free. From the experimental results it is clear that the mode shapes are more distinctly visible with the implementation of the new filtering scheme as compared to other known schemes. Under both the boundary conditions the recorded resonance frequencies were compared with the calculated values of resonance frequencies based on classical theory. The results obtained form DSPI show good agreement with classical theory.     

Investigation of the diffusion of phosphorus through a film of SiO2 by the radioactive tracer method

A solution of the diffusion equation in a double-layer system from a prompt source of diffusion is obtained, and a method is described for determining the fundamental parameters of the diffusion in a double-layer system by removing layers and measuring the overall activity of a fragment of the specimen. The diffusion of P³² at temperatures from 1100–1260°C is investigated in films of SiO₂ deposited on Si in a high-frequency electrodeless plasmotron. The diffusion coefficients in the film and the values of the segregation coefficient at the boundary of separation of the SiO₂-Si system are determined.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 29–35, May, 1976.     

The use of domain boundary resonance for study of the magnetization process in systems of lithium ferrites

The change in absorption spectra of lithium ferrite-aluminates produced by domain boundary resonance in an external magnetic field is studied. The character of the absorption spectrum change is compared with the real portion of the radio-frequency magnetic permeability as a function of the field. It is concluded that it is possible to study the process of magnetization by the domain boundary resonance method.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 52–56, July, 1973.     

Electron paramagnetic resonance (EPR) spectra of Mn++ at normal and defect sites of a crystalline ZnS lattice

Three EPR spectra (one cubic and two axial) of Mn⁺⁺ in ZnS crystals grown from a melt are detected and investigated. On the basis of an analysis of these spectra, the deduction is made that wurtzite inclusions are monotetrahedral layers on the twinning boundary, where the twinning boundary occurs in every 20–25 layers of the sphalerite stacking.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 44–49, October, 1973.     

Method for solving heat-conduction boundary-value problems in a region with a boundary in uniform motion

A modification of the Lyubov method is used to solve boundary-value problems of the head-conduction (or diffusion) equation near a boundary in uniform motion.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 62–71, January, 1971.     

Unidirectional transmission of electrons in a magnetic field gradient

This work presents an experimental demonstration of time-reversal asymmetry of electron states propagating along the boundary separating areas with opposite magnetic fields. For this purpose we have fabricated a hybrid ferromagnet– semiconductor device in the form of a Hall cross with two ferromagnets deposited on top. The magnets generated two narrow magnetic barriers of opposite polarity in the active Hall area. We have observed that if the signs of the barriers are reversed, the bend resistance changes its sign. Using the Landauer–Büttiker theory, we have demonstrated that this is a direct consequence of asymmetric transmission of the “snake” and the “cycloidal” trajectories formed at the boundary separating the regions with opposite magnetic field directions.     

Amplifying properties of a synchronized generator

The amplifying properties of a synchronized generator are explained on the basis of an autoparametric model of the synchronization phenomenon.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 59–63, December, 1981.     

K–K excitations on as “primary” superfields

We show that the K–K spectrum of IIB string on is described by “twisted chiral” superfields, naturally described in “harmonic superspace”, obtained by taking suitable gauge singlets polynomials of the D3-brane boundary superconformal field theory.To each p-order polynomial is associated a massive K–K short representation with states. The quadratic polynomial corresponds to the “supercurrent multiplet” describing the “massless” bulk graviton multiplet.