Average Intensity of Low-Frequency Sound and Its Fluctuations in a Shallow Sea with a Range-Dependent Random Impedance of the Liquid Bottom

In this study, the problem of the influence of a horizontally inhomogeneous liquid bottom impedance, given by random Gaussian function of the speed of sound and by density, on the propagation of low-frequency sound in a shallow-water waveguide is considered. The model parameters are referenced to the conditions of sound propagation in the regions of the seas of the Russian Arctic shelf. By the example of statistical modeling of the sound field intensity, we show that sound speed fluctuations in the bottom lead to similar effects that were previously established for volumetric fluctuations of the speed of sound in the water layer. With the distance from the source, the decrease in the average intensity slows down in comparison with a deterministic medium in which there are no fluctuations. This deceleration of the decay of the intensity in a random waveguide can be significant already at short distances. Changes in the law of decay of intensity at a fixed frequency are mainly determined by the correlation radius of inhomogeneities and the average penetrability of the bottom, which leads to attenuation of sound propagating in the waveguide.

Synthesis of the optimal algorithm and structure of contactless optical device for estimating the parameters of statistically uneven surfaces

The production of parts and (or) finished products in electronics, mechanical engineering and other industries is inextricably linked with the control of the accuracy and cleanliness of the processed surfaces. Currently existing meters of parameters of statistically uneven surfaces, both contact and non-contact have some disadvantages, as well as limitations due to methods and design features of measurement. Speckle interferometric methods for measuring parameters of statistically uneven surfaces make it possible to get away from some disadvantages inherent in existing methods and measurements. The use of methods of statistical radio engineering, methods of optimization of statistical solutions and estimates of parameters of predictive distributions for optimal radio engineering system synthesis is promising for the analysis and processing optical-electronic coherent laser space-time signals (speckle images) form with the laser radiation scattered by statistically uneven surfaces. This work synthesizes the optimal algorithm and structure for analyzing the parameters of statistically-temporal surfaces based on spatio-temporal processing of optical speckle interference signals and images using modern methods of optimal synthesis of radio engineering and coherent optoelectronic systems. In this work, an algorithm for processing optical signals scattered by statistically uneven surfaces is synthesized and investigated for problems of optimal estimation of parameters and statistical characteristics of statistically uneven surfaces. A block diagram of the optical contactless device for evaluating the parameters of statistically uneven surfaces is proposed. The limiting errors of estimation parameters of statistically uneven surfaces and the optimal installation angles of the emitters and the optical receiver are investigated. Equations are obtained for estimating the root-mean-square height of the ridges and the correlation radius of small-scale statistically uneven surfaces in the approximation of small perturbations. The proposed method for evaluating the parameters of statistically uneven surfaces allows to increase the accuracy of measurements, to conduct a non-contact assessment of the parameters - even statistically uneven surfaces that have geometric surface irregularities or located in hard-to-reach places, for example, grooves, holes, as well as products of cylindrical, spherical and other shapes.

Modeling of quantum-like cognitive phenomena by the Fourier-holography technique under the choice of alternatives

The article is dedicated to the search for a biologically motivated mechanism of the cognitive phenomenon of violation of the classical formula of total probability for the disjunction of incompatible events, which is considered by a number of researchers as a quantum-like phenomenon. A classical mechanism implemented by the 6f Fourier holography scheme of the resonant architecture that does not require reference to quantum mechanics either in its physical nature or at the level of formalism is demonstrated. In the analysis, the decision-making is interpreted as a choice of alternatives by using the non-cooperative game "Prisoner's Dilemma". The approach to the task is based on the search for a mechanism for forming a conditional estimate under a condition that contradicts the rule of monotonous decision logic. It is demonstrated that this estimate, in contrast to the unconditional and conditional one with a non-contradictory condition, is formed by logic with exception. The ring architecture of the holographic setup corresponds to the biologically inspired neural network concept of the excitation ring and implements cognitive dissonance on logic with exception. Conditions and ranges of violation of the classical formula of total probability in relation to the correlation radius of the reference image recorded in a hologram storing the monotone logic inference rule are analytically determined. The analytical model is confirmed by a quantitative coincidence of the results of numerical modeling with the published results of natural experiments.

Multi-Aperture Optical System of Photon Counting in the Image for Aberration-Free Space Debris Observations through a Turbulent Atmosphere (Part II)

The paper considers the principles of construction and application strategies of the ground optical system for space debris monitoring protected by the patent of the Russian Federation for the invention. The aim of this invention was to increase the diffraction resolution of the formed images of a small space object and improve the accuracy of restoration of the module undistorted by the atmosphere and phase of its spatial spectrum. To achieve this goal, formation of atmospherically distorted images of a space object is carried out by a coherent matrix of M moving telescopes of the diameter D in the process of space-time aperture synthesis, which directs the combined subbeams from moving telescopes along the tracks to the center of the matrix, where the stationary base is placed, which performs both coherent combination of subbeams and detection of formed series of N images with their subsequent registration and processing. During statistical processing of moduli and phases of spatial spectra of registered images, the island nature of the optical transfer function (OTF) of matrix along the ellipses of coherence and its semi-island in the radial direction extending from the center of the spatial frequency domain to the cutoff frequency of the synthesized aperture of the diameter Dэ is taken into account. The positive effect of using this invention is that the coherent operation of the matrix provides a gain in the diffraction resolution of Dэ/D times (Dэ/D 1), and an increase of D/r0 times, where r0 is the atmospheric fluctuations correlation radius, the accuracy of restoration of the undistorted by the atmosphere module and phase of the space spectrum from the object by the proposed smoothing procedure allows reducing by the same factor (D/r0 1) the required number of N registrations in series reducing the total monitoring time.

Local Magnetic Anisotropy of the Co-Based Amorphous Alloy

The magnetization, initial magnetic susceptibility, and magnetostriction of a multicomponent Co-based amorphous alloy have been studied. The exchange constant a and the Curie temperature TC of the alloy are determined. On the basis of a method based on the theory of stochastic magnetic structure for amorphous ferromagnets and using the magnetization curves, the correlation field Hℓ, the field Ha, the effective constant of local magnetic anisotropy Keff, and the stochastic characteristics of local anisotropy – the mean square field fluctuations and the correlation radius – have been calculated. The temperature behavior of the examined magnetic characteristics is analyzed. The results of magnetostriction research allow a conclusion to be drawn that the local magnetic anisotropy of the alloy has a single-ion origin.

Introducing Along-Track Error Correlations for Altimetry Data in a Regional Ocean Prediction System

Because of the systematic error in the processing of altimetry data, sea level anomaly (SLA) observation errors are likely affected by nonnegligible spatial correlations. To account for these, we exploit the synergy of altimetry data with in situ profiles from gliders, piloted to follow the altimetry tracks during the Long-Term Glider Mission for Environmental Characterization 2017 (LOGMEC17) observational campaign in the Ligurian Sea. The assimilation of along-track unfiltered sea level anomalies in a regional ocean analysis and forecast system is consequently optimized by means of introducing spatial correlations for the SLA observation errors. In particular, collocated data of glider and altimetry are used to derive an along-track error covariance model for the sea level anomaly assimilation, assuming that most of the covariance behavior versus separation distance stems from altimetry. Spatial scales of the altimetry error are found to have a correlation radius of about 12 km for the dataset utilized in the Ligurian Sea, using a simple Gaussian shape for the error correlation, shorter than the correlation radius found through assimilation output diagnostics. A variational data assimilation system is modified to relax the usual assumption of uncorrelated altimetry observation errors, thus allowing for along-track error correlations. Its implementation provides promising results in the regional ocean prediction system, outperforming in most verification skill scores the use of uncorrelated observational errors without compromising the analysis scheme efficiency.

Bose–Einstein Correlations in pp and pPb Collisions at LHCb †

Bose–Einstein correlations for same-sign charged pions from proton–proton collisions at s = 7 TeV are studied by the Large Hadron Collider beauty (LHCb) experiment. Correlation radii and chaoticity parameters are determined for different regions of charged-particle multiplicity using a double-ratio technique and a Levy parametrization of the correlation function. The correlation radius increases with the charged-particle multiplicity, while the chaoticity parameter decreases, which is consistent with observations from other experiments. A similar study for proton-lead collisions at s N N = 5 . 02 TeV is proposed. These results can give valuable input for the theoretical models that describe the evolution of the particle source, probing both its potential dependence on pseudorapidity region and differences between proton–proton and proton–lead systems.

Критические свойства в модели Изинга на треугольной решетке с переменным межслойным обменным взаимодействием

The Monte Carlo replica algorithm studies of phase transitions and critical phenomenaofthe layered triangular antiferromagnetic Ising model withvariable interlayer exchange interaction. Investigations were carried out for the ratios of the value of the intralayerJ1 and interlayer J2 exchange interactions in the range of values r = J2 / J1 = 0.01 ÷ 1.0. It was found that in the above range r is observed second-order phase transition.Static critical exponents for the heat capacityα, susceptibility γ, order parameter β, correlation radius ν, and the Fisher exponent ηare computed by means of the finite-size scaling theory. It is shown that the universality class of the critical behavior of the model is maintained in the range of 0.05 <r≤1.0.The results obtained suggest that3D frustrated Ising models on stacked triangularlattice with interlayer-to-intralayer exchange ratio 0.05<r≤1.0. preserves the universality class of criticalbehavior. At lower r, a crossover from 3D to 2D criticalbehavior is observed.