Vol 71, No 3 (2025)

The self-consistent problem of dynamic behavior of a deformable system consisting of a two-dimensional elastic guide (subsystem 1) and a one-dimensional elastic object (subsystem 2) continuously moving along it is considered. Local and global laws of change in energy and wave momentum are presented in the case when the Lagrangians of the contacting subsystems depend on generalized coordinates and their derivatives of no more than the second order with respect to all space-time variables. Radiation conditions in the considered class of systems are discussed. A comparative analysis of both dispersion and energy characteristics of flexural waves propagating in plates described by two different models is carried out. Critical velocities of motion of a constant load along these plates are found. The dependence of critical velocities on the rigidity coefficient of the elastic foundation and the physical and mechanical properties of the plate is established. The fundamental possibility of converting the energy of oscillations of a two-dimensional elastic guide into the energy of translational motion of a one-dimensional object is demonstrated. The force caused by the wave pressure acts as a mediator of such transformation, the expression for which is obtained in a universal form through the Lagrangian of a two-dimensional system. The dependence of the coefficient of transformation of wave energy into the energy of translational motion of an absolutely rigid fastening on the speed of its motion and the parameters of a two-dimensional system is constructed.

Vibration impact on a liquid drop has attracted increasing interest in connection with the study of complex self-organization processes in solutions. The practical value of such studies is associated with applications in chemistry, biology, medicine, and materials science (directed self-assembly of nanostructures in an evaporating drop). The paper presents a theoretical study of hydrodynamic flows of complex configuration excited by acoustic impact in a hemispherical drop deposited on a vibrating substrate.

The results of the development of highquality resonators based on STW (Surface Transverse Waves) are presented. It is shown that through the use of modern computing programs (COMSOL Multiphysics), as well the improvement and development of already known calculation methods (modified coupling of modes model), it is possible to efficiently and quickly calculate devices on surface acoustic waves. The results of comparing the theoretical and experimental responses of the transmission coefficient of a two-port STW resonator are presented. It is shown that highquality resonators at frequencies of 0.5...2.5 GHz can be manufactured on the basis of standard optical lithography. Typical values of the unloaded Q-factor of resonators at a frequency of 500 MHz are 27000...29000. The measurements of a two-port STW resonator made as part of a 500 MHz low-noise oscillator layout are presented, which demonstrate a phase noise level of −148.7 dBn/Hz at 1 kHz detuning and −183.5 dBn/Hz at 1 MHz detuning from the carrier frequency, a jitter 2.8 fs. Self-oscillators based on STW resonators with a low level of phase noise and a low jitter value can be in demand in areas where it is critically necessary to ensure the maximum dynamic range of digital signal processing paths.

The article is devoted to determining the optimal parameters of sounding signals of a hydroacoustic system for monitoring temperature regimes of sea water areas on a thousand-kilometer scale. The results of modeling the noise immunity of complex signals of various durations and resolutions are presented. The results of modeling and full-scale tests on an acoustic path with a length of 1073 km in the Sea of Japan are presented. The influence of the waveguide impulse response on the noise immunity of signals with different resolutions is shown. Preferred sequences of sounding signals have been determined.

The impact of seabed characteristics on the accuracy of determining the distance between a sound source and receiver located underwater was studied within the framework of numerical experiments. Experimental data on bottom parameters and the sound speed profile in the water layer in summer and winter (hydrological) seasons in the shallow water part of the Kara Sea were used. In the latter case, the action of ice cover was taken into account. It has been found that the main error in determining the distance in the interval of 1–10 km is associated with the multimode (multiray) nature of the propagation of acoustic waves in the sound channel between the water surface and the bottom. It has been demonstrated that this error decreases to several meters in the summer and with a water-like bottom, when the sound speeds in the water layer and in the bottom are close to each other. It has been noted that horizontal refraction of acoustic waves caused by transverse inhomogeneity of the bottom also leads to errors in determining the distance, although to a lesser extent.

The paper presents the result of using a previously developed method for three-dimensional localization of acoustic sources based on data from non-synchronous measurements with a multi-microphone array from various positions, adapted for dipole-type sources characteristic of airframe noise. The work consists of two parts. In the first, the developed method was verified using the example of localization of test dipole sources. Sources with different orientations of the dipole moment relative to the edges of the microphone array are considered. Based on the results of localization of test sources, it is shown that a dihedral array, the faces of which are parallel to the dipole moment of the source, allows for more accurate identification of a dipole source in three-dimensional space compared to the general case. In the second part of the work, the method is used to construct three-dimensional noise sources localization maps of a small-scale high-lift wing model with an imitation of extended landing gear, which has a complex structure of dipole sources of various amplitudes and directions. An analysis of the obtained volumetric localization maps in various frequency bands was carried out by comparing such localization with test cases and the possibility of localizing sources under study was shown.

The sensitivity of the amplitude on the surface of a surface acoustic wave (SAW) to a change in the elastic parameters of a layered half-space with a smooth change in its elastic parameters horizontally is considered. The cases of wave transition from a single-layer system to a single-layer system and from a multilayer to a multilayer system are analyzed using the example of a five-layer system with an independent change in the velocities of longitudinal and transverse waves in the layers. It is shown that the properties of the reference medium affect the resulting dependences of the relative amplitude on the frequency. The sensitivity of the wave amplitude to local changes in parameters in a multilayer system varies significantly depending on the frequency. In the case of a constant Poisson's ratio, the mechanism of amplitude variation on the surface is demonstrated based on the analysis of the surface wave profile.

The article describes the methodology and presents the results of marine experiments on the construction and analysis of direction-finding reliefs and recorded trajectories from the standpoint of classification of observed sources (surface and underwater objects) in the noise direction-finding mode as applied to autumn hydroacoustic conditions in the coastal area wedge. It is shown that in the noise direction finding mode, as an additional to the known classification features for separating surface and underwater objects, the modulation of the trajectory bearing, which occurs when signals are propagated with reflection from the boundaries — the surface and the bottom, can be used. This modulation is effectively detected after limiting the power of strong signals.

The study tested the hypothesis, that speech changes in noise (the Lombard effect) may have significant individual differences, including those due to the gender and age of the speakers. For this purpose, the characteristics of Lombard speech were studied for 12 speakers (6 men, 6 women; 25–35 and 55–59 years). The study used recordings of speech, consisting of disyllabic words with stressed vowel sounds [a], [i], [u] of Russian speech in silence and in multi-talker noise at levels of 60 and 72 dB(A). Changes in the fundamental frequency (ΔF0) and intensity (ΔI) of the voice in noise compared to silence were determined. When comparing groups of men and women, significant differences in the change of F0 in noise of 60 dB are shown. Differences in vowel characteristics between the young and middle-aged speaker groups were found for ΔF0 and ΔI in 72 dB noise. Regardless of gender and age, two types of speakers were identified, differing in the values ​of ΔF0 and ΔI at both noise levels. Speakers of the first type in multi-talker noise increased F0 by 23 and 57 Hz, for levels of 60 and 72 dB, respectively, and speakers of the second type — by 16 Hz and 23 Hz. The voice intensity of speakers of the first type for two levels of noise masker increased by 8 and 16 dB; the second type — at 6 and 10 dB. The obtained differences may be determined by the greater influence of voluntary control, with an increase in the noise level in speakers of the second type we have identified.