Study of the Mechanism of the Autowave Structure Formation at the Reaction Front

A qualitative mechanism of the formation of wave structures at the reaction front is proposed. It is assumed that the structures are formed as a result of the interaction of two subsystems, one of which is responsible for the front formation, and the other is responsible for the formation of structures themselves. Three models are considered; two-dimensional analogues of concentric and spiral waves are numerically demonstrated in each. Fitzhugh–Nagumo, Fisher–Kolmogorov–Petrovskii–Piscounov (Fisher–KPP), and Oregonator models were used as subsystems.     

On the Finite Brst Transformations: the Jacobians and the Standard Model with the Gauge-Invariant Gribov Horizon

Russian Physics Journal - A review of the finite field-dependent Becchi–Rouet–Stora–Tyutin (BRST) and BRST-antiBRST transformations is presented. Exact rules for calculating the...     

Determination of the interaction using FTIR within the components of GPE based on the synthesized grafted polymer

An oxyethylene chain (–CH₂–CH₂–O–) grafted polymer (P(MMA–MAh)–PEGME) was synthesized by reacting poly(ethylene glycol) monomethyl ether (PEGME) with the copolymer of poly(methyl metacrylate–maleic anhydride) (P(MMA–MAh)) and endcapping the residual carboxylic acid with methanol. Rectorite modified with dodecyl benzyl dimethyl ammonium chloride (OREC) was used as a filler additive to modify gel polymer electrolytes (GPE) that consisted of P(MMA–MAh)–PEGME used as polymer matrix, propylene carbonate (PC) as plasticizer and LiClO₄ as lithium ion producer. Characterization of interaction of the polar group of C=O or C–O–C in PC and grafted polymer with Li⁺ and OH group on OREC surface has been thoroughly examined using Fourier transform infrared (FTIR), respectively. The quantitative analysis of FTIR shows that the absorptivity coefficients (a) of polymer/LiClO₄, PC/LiClO₄, PC/OREC and polymer/OREC are 0.705, 0.113, 0.430 and 0.500, respectively, which means that the Li⁺ or OH bonded polar group of C=O and C–O–C is more sensitive than free C=O and C–O–C in FTIR spectra. The limited values of bonded C=O and C–O–C equivalent fraction of polymer/LiClO₄, PC/LiClO₄, PC/OREC and polymer/OREC are 33%, 94%, 60% and 22%, respectively, which implies that the interaction within the components is reversible and the intensity of interaction is ordered as PC/LiClO₄, PC/OREC, polymer/OREC and polymer/LiClO₄.     

Optimising the absorption and transmission properties of aircraft microperforated panels

A method for evaluating the absorption and transmission performances of multi-layer micro-perforated structures whose facings are excited by different noise sources is described here. It is applied to determine if the acoustical performances of a number of Micro-Perforated Panels (MPPs), optimised both in absorption and transmission, exceed those of typical aircraft panels undergoing internal and external acoustic excitations. A fully-coupled modal formulation is presented that accounts for the effects of the sub-structure volumetric resonances on the acoustical properties of the partitions. It is validated against full-scale measurements performed with a pressure–velocity probe and a laser vibrometer to estimate the absorption and transmission coefficients of single- and double-layer micro-perforated partitions. The model is used to optimise the sound power dissipated by three layouts obtained from a typical aircraft partition by micro-perforating the trim panel (MPP–Porous–Panel), removing the fibreglass material (MPP–Cavity–Panel) and adding a second MPP inside the separating cavity (MPP–MPP–Panel). It is concluded that the MPP–Porous–Panel and MPP–MPP–Panel layouts provide excess interior noise reduction above 1.8 kHz and 1.2 kHz respectively, whereas the MPP–Cavity–Panel is not acoustically more efficient than a typical aircraft panel.     

Effect of the Ba+ Ion Implantation on the Composition and Electronic Properties of MoO3/Mo(111) Films

Technical Physics - It is shown that a film consisting of the Mo–O, Mo–Ba–O, and Ba–O compounds is formed in the ion-implanted layer upon implantation of MoO3 with the Ba+...     

Density of states of narrow superconducting channels in the regime of quantum fluctuations of the order parameter

The current–voltage characteristics of superconductor–insulator–semiconductor (S1–I–S2) tunnel junctions, where superconducting electrode S2 is a thin nanowire, are studied experimentally. The observed blurring of the gap singularities is interpreted as a manifestation of the order parameter quantum fluctuations. We propose a model taking into account the broadening of the density of states due to the interaction of electrons with the Mooij–Schön plasmon mode emerging in a quasi-one-dimensional superconducting channel in the regime of quantum fluctuations of the order parameter. The model gives results that are in a reasonable qualitative agreement with the experimental data.     

Luminescence investigation of the surface states of η-alumina. Correlation with the infra-red study of the evolution of the surface hydroxyl groups

The two techniques of luminescence and of infra-red spectrophotometry have been used in an attempt to characterize surface states of η-alumina. Infra-red absorption bands of hydroxyl groups of different coordinations are observed, in agreement with previous results, and evolution of hydroxyl groups according to different treatments allows a luminescence at about 440–450 nm excited at 350–360 nm to be ascribed to these groups. Luminescence with an apparent maximum of 390 nm excited at 250 nm is attributed to internal vacancies, and luminescence with a maximum at 480–500 nm excited at 270–280 nm is attributed to surface vacancies.     

Landau-type pressure dependence of the order parameter: application to the ferroelectric-paraelectric pressure-induced transition in KNbO3

Following the Landau model, the pressure–temperature dependence of the order parameter is derived. Using the Lyddane–Sachs–Teller (LST) relationship, the model is applied to ferroelectricity to deduce the pressure behaviour of the soft mode driving the transition. Comparison with experiment is made using recent data obtained on KNbO₃ under pressure over a large temperature range. The results indicate that the ferroelectric–paraelectric (FE–PE) transition observed in KNbO₃ at high pressure from ～4 to ～25?GPa is of the second-order type.     

Lax pair,infinitely-many conservation laws and soliton solutions for a set of the time-dependent Whitham-Broer-Kaup equations for the shallow water

Under investigation in this paper is a set of the time-dependent Whitham–Broer–Kaup equations, which is used for the shallow water under the Boussinesq approximation. The equations can be transformed into generalized time-dependent coefficient Ablowitz–Kaup–Newell–Segur system via the variable transformation. Lax pair, infinitely-many conservation laws and bilinear forms of the Ablowitz–Kaup–Newell–Segur system are obtained. One-, two- and three-soliton solutions are derived via the Hirota bilinear method. The solitons are physically related to the horizontal velocity field and height that deviates from equilibrium position of the water. Features of the solitons are studied: Soliton amplitude is related to the wave number parameters, while the soliton velocity is related to the wave number parameters and variable coefficient. Interactions between/among the solitons could be elastic or inelastic, determined by the wave number parameters. Interaction property could not be affected by the variable coefficient. Soliton stability is studied via the numerical calculation, which indicates that the solitons could only propagate steadily in a limited time.     

To the theory of I–V characteristics of the superlattices

The influence of inelastic scattering on the I–V characteristics of “dirty” and “pure” superlattices (SL) in the quasielastic limit is studied. It is shown that the form of the I–V characteristics of “dirty” SL is determined solely by the frequency of elastic scattering in a wide range of parameters and that the electron-phonon interaction in “pure” SL leads to the formation of two regions with negative differential conductivity (NDC) on the I–V characteristics.     

To the theory of current transport in the mechanically controllable break junctions

The transport mechanisms for metal–molecule–metal junction after break are analyzed. Theoretical expression for the threshold voltage for transmission from the direct tunneling current to the Fowler–Nordheim tunneling is obtained and analyzed. It is show that threshold voltage depends on the electrode metal work function and displacement. With the increase in displacement the threshold voltage quickly decreases. Differential resistances for the low and high voltage modes increase with increasing in the displacement, and in the Fowler–Nordheim tunneling mode the differential resistance increases when voltage is decrease. It is shown that for the cases commonly used metals (Ag, Au, Pt) the threshold voltage is linearly dependent on the work function of metals.     

Maximizing the population inversion by optimizing the depopulation rate in far-infrared quantum cascade lasers

Electron–LO phonon and electron–electron transition rates are calculated for a three-level triple quantum well system to be employed as a laser operating in the far-infrared (30–300 μm) or terahertz (1–10 THz) region. The population ratio is determined from the ratio of the carrier lifetimes in levels |3〉 and |2〉. The most effective way of depopulating the lower laser level is found to be by LO phonon scattering to a strongly coupled state, as occurs at an anticrossing. Back scattering of carriers from level |1〉 to level |2〉 is significant at room temperature, but a population ratio of approximately 5 is possible nonetheless.     

Verification of the Numerical Model in the Problem of Studying Directional Characteristics of Sound Radiation from Inhomogeneous Shells

Results of verifying the levels and directional characteristics of sound radiation are presented for a finite-element numerical model of a submerged inhomogeneous shell. The error in numerical modeling of directional characteristics is determined for sound radiation from shell parts with one-layer (shell–liquid) and multilayer (shell–liquid–shell–liquid) structures.     

Microstructure of the Magnetic Field on the Surface of a Permanent Magnet

A Nd–Fe–B permanent magnet is studied by means of atomic force microscopy. Phase diagrams are obtained at the center and at the edge of the sample. The homogeneity of the magnetic structure is investigated.     

An extension of the modified Sawada—Kotera equation and conservation laws

Based on the modified Sawada-Kotera equation, we introduce a 3 × 3 matrix spectral problem with two potentials and derive a hierarchy of new nonlinear evolution equations. The second member in the hierarchy is a generalization of the modified Sawada-Kotera equation, by which a Lax pair of the modified Sawada-Kotera equation is obtained. With the help of the Miura transformation, explicit solutions of the Sawada-Kotera equation, the Kaup-Kupershmidt equation, and the modified Sawada-Kotera equation are given. Moreover, infinite sequences of conserved quantities of the first two nonlinear evolution equations in the hierarchy and the modified Sawada-Kotera equation are constructed with the aid of their Lax pairs.     

Atom–field entanglement at the collapse region

It is shown that the atom–field interaction, in the context of the Jaynes–Cummings model, leads periodically to a Schmidt decomposition of the atom–field state at times within the first collapse region. For some initial average photon number maximally entangled atom–field state are generated.     

Some Thermodynamic Characteristics of Paracetamol Dispersing with the SEDS Method

The solubility of paracetamol in supercritical carbon dioxide and its mixtures with acetone is experientially studied. The isobaric heat capacity of paracetamol and the systems “paracetamol–CO₂” and “paracetamol–acetone–CO₂” is measured under pressures 7–29 MPa and temperatures 303–523 K. The results of paracetamol dispersing using the SEDS method (Solution Enhanced Dispersion by Supercritical Fluids) are presented.     

Experimental Investigation into the Low-Molecular-Weight Fluoropolymer for the Storage of Ultracold Neutrons

The experimental setup for examining the low-molecular-weight CF₃(CF₂)₃–O–CF₂–O–(CF₂)₃CF₃ fluoropolymer, which is a promising coating material for the walls of storage chambers for ultracold neutrons, is described. The results are detailed. The measurement data are interpreted in the model of a multilayer complex quantum-mechanical potential of the chamber walls.     

On array models theoretical predictions versus measurements for the growth of cells and dendrites in the transient solidification of binary alloys

Most of the theoretical studies of the growth of cells/dendrites in the literature are based on the assumption that it is a steady-state phenomenon. The analysis of cells/dendritic structures in the unsteady-state regime is very important, since it encompasses the majority of industrial solidification processes. The aim of the present investigation was to validate the predictions furnished by the cellular and primary dendritic growth models in the literature for unsteady-state conditions against a large spectrum of experimental data, which includes those for a variety of Al alloys (Al–Cu, Al–Si, Al–Fe, Al–Bi, Al–Ni, Al–Sn) and low thermal diffusivity alloys, such as Sn–Pb and Pb–Sb. The predictions furnished by the Hunt–Lu model do not match the cellular experimental scatter for any examined alloy system. However, this model matches well with the primary dendritic growth of Al alloys, with the exception of Al–Sn alloys, for which the Hunt–Thomas approach has to be applied. The primary dendritic predictions of Bouchard–Kirkaldy's model, performed with the originally suggested a ₁ calibration factors are, in most cases, located above the experimental points. Experimental growth laws relating cellular and dendritic spacings with the tip growth rate and the cooling rate, respectively, are established.     

Relaxation method for constructing the interaction potentials of metal–nonmetal atomic pairs

An algorithm that employs the method of successive relaxation for determining the parameters of the pairwise interaction potential of iron and nonmetallic atoms that implicitly considers the redistribution of electron density between atoms is developed. The parameters of the interatomic interaction potential are calculated for ten pairs of elements: Fe–P, Fe–S, Fe–B, Fe–V, Fe–Mo, Fe–Cr, Fe–Mn, Fe–Si, Fe–Ni, and Fe–Al. The structural and thermodynamic properties of solid solutions based on iron and pure materials, and some pairwise interaction potentials constructed earlier in the Lennard–Jones form for identical metal atoms and homogeneous pairs of different metal–metal atoms, are used in these calculations.