The article is devoted to the analysis of the spatial structure of acoustic pressure and particle velocity fields in hydroacoustic waveguides of the sea shelf. Waveguides with two types of sound velocity profile are considered: constant and having an underwater sound channel. The bottom is assumed to be a transitional layer with a sound velocity gradient and a half-space. The acoustic properties of the layer are assumed to be those of silt or sand. The interference structure of the pressure field and the field of the vertical component of the particle velocity is analyzed. The spatial laws of attenuation pressure and particle velocity fields are analyzed. It is shown that the interference structure and the laws of decrease of the pressure field and the vertical component of the particle velocity do not coincide. The article is devoted to the analysis of the spatial structure of acoustic pressure and particle velocity fields in hydroacoustic waveguides of the sea shelf. Waveguides with two types of sound velocity profile are considered: constant and having an underwater sound channel. The bottom is assumed to be a transitional layer with a sound velocity gradient and a half-space. The acoustic properties of the layer are assumed to be those of silt or sand. The interference structure of the pressure field and the field of the vertical component of the particle velocity is analyzed. The spatial laws of attenuation pressure and particle velocity fields are analyzed. It is shown that the interference structure and the laws of decrease of the pressure field and the vertical component of the particle velocity do not coincide.

Keywords: normal modes, particle velocity, seabed, interference structure, incoherent addition

Bottom sediments (UP to) are media in which both longitudinal and shear acoustic vibrations can be present. The presence of several velocity components in bottom sediments makes it possible to excite various types of waves, both longitudinal and shear. In this paper, methods of excitation, generation and reception of difference frequency shear waves (RF) created by parametric systems in (DO) in location modes are analyzed. The analysis of their work in the DO is presented, and their comparative characteristics are given in comparison with the excitation, formation and propagation of the field of longitudinal RFCs in the DO. Prerequisites are given for the creation of a parametric profiler working using the method of excitation, generation and location of shear waves in a complex multiphase medium ""water-DO"". A block diagram is presented and the principle of operation of a parametric profiler on shear waves is described. The advantages and disadvantages of this method of location are shown. The conclusion is made about the possibility of creating and ration.

Keywords: parametric antenna, bottom sediments, shear waves, difference frequency waves, parametric profilogaf

The search and determination of the amount of biological resources is an urgent task, both from the point of view of food security of the Russian Federation and from the point of view of ecology. Most of the biological resources in the ocean are concentrated in shallow water zones (at depths from 1 to 200 m). The paper presents the results of the development of a parametric traverse survey sonar for searching for biological resources in shallow water. The calculation of the energy range of the parametric traverse sonar is given. The full-scale sea tests of the developed model of the traverse survey sonar in the Taganrog Bay of the Sea of Azov (shallow water conditions) are given. The average depth of the landfill was 2.2 meters. The oscillogram of the echogram recording line when determining the maximum detection range of a target in shallow water (reflected signal from a target at a distance of 1100 m) and an echogram from a target that moves away from the traverse sonar antenna at a distance of up to 800 m are given. Conclusions are drawn about the prospects of using parametric traverse-view sonars to search for fish aggregations in shallow water.

Keywords: traverse survey, parametric sonar, search for biological resources, shallow water, energy range

The problem of studying the peculiarities of sound propagation in shallow seas is an urgent task of hydroacoustics, since it is associated with human production activities in coastal zones and waters of shallow seas. A shallow sea for a sound field is a waveguide in which certain modes propagate. Features such as "extinction" modes and dispersion distort the picture of the sound field. There is also a complex interference situation due to reverberation interference and multiple re-reflections. To avoid information loss, it is proposed to use narrowly directed parametric radiation without side lobes. The issues of equipment selection are considered, the law of temporary automatic gain control (TAGC) for the study of bottom layers is calculated. The results of the analysis of echograms for depths of 1-2 m are presented. The possibility of identifying layers and anomalies is shown.

Keywords: shallow sea, sound propagation, modality, waveguide, TAGC's law, structure data, layers, profilograph, anomalies

The article considers the influence of external noise sources on humans and the environment as an environmental factor and ways to combat noise. The aim of the work is to study the external enclosing structures of residential buildings, the facades of which are oriented to a noisy highway on the example of residential complexes of the city of Rostov-on-Don and noise screens installed on the highway along the residential development of the city of Bataysk, Rostov region. A practical method of measuring the noise level using a noise meter is used. Acoustic measurements of the noise level were carried out, which made it possible to conclude about the effectiveness of the noise protection structures provided. It has been experimentally established that noise-proof structures reduce the sound pressure level to an acceptable level. When designing residential buildings, a simultaneous calculation of noise protection and thermal protection of buildings is necessary, determining the materials, the design of the outer wall, the thickness of the insulation layer and the choice of noise-proof windows. To improve the noise ecology near residential buildings and federal highways, it is recommended to use modern technologies for the construction of noise screens. According to the research results, it can be concluded about the effectiveness of the use of noise screens during their continuous construction along the highway.

Keywords: noise, noise protection, noise shield, noise-proof structures, sound power level, sound insulation, ecology

The article is devoted to the analysis of the vertical structure of the acoustic pressure field and the first-mode particle velocity in a hydroacoustic waveguide in shallow water. A waveguide consisting of a water layer with a constant sound velocity profile, a transition layer, and a half-space is considered. The acoustic properties of the transition layer are assumed to be frequency dependent. Formulas are derived that describe the vertical profile of the normal mode of a particle velocity. The transformation of the vertical profile of the first mode with increasing frequency is analyzed. The phase difference relations between the normal mode of acoustic pressure and particle velocity are analyzed. A relationship is established between the change in the vertical structure of the normal modes of pressure and particle velocity and the acoustic properties of the transition layer.

Keywords: normal modes, particle velocity, seabed, attenuation coefficient

This article presents the results of identification and assessment of the factors of the working environment, as well as highlights the vibroacoustic factors that have the greatest impact on the working capacity and health of the operators of hoisting machines.

Keywords: identification, hoisting machines, acoustic discomfort, noise and vibration spectra, working conditions

The possibility of using nonlinear effects in hydroacoustic systems with parametric radiation mode for profiling the bottom and bottom sediments attracts the attention of both domestic and foreign specialists. The use of parametric antennas in hydroacoustic equipment allows, due to their high directivity and low side field level, to increase the information content and accuracy in detecting and determining the coordinates of underwater objects, and to obtain additional features for recognition. The efficiency of using a parametric profiler for solving problems that require high resolution is justified. A block diagram of a parametric profiler for studying the layered structure is developed. The features of the signal generator and the amplification unit are considered. The characteristics of the radiating antenna were measured under laboratory conditions. It is shown that the directivity characteristic is constant in the operating frequency range and the acoustic power at the output makes it possible to solve the tasks of sounding up to 10 m into the ground. A record of the soil profile was obtained, confirming the operability of the system. In the future, the results will be used in full-scale conditions with the use of cepstral echo processing.

Keywords: profilograph, parametric antenna, kepstr, block diagram, signal generator, power amplifier, directional pattern, amplitude-frequency response, pump antenna, ground profile

The use of a separate receiving antenna at different frequencies in parametric acoustic systems is associated with the irreversibility of nonlinear processes underlying its principle of operation. The paper considers the results of experimental and theoretical studies to assess the influence of external elements on the amplitude-frequency response of a piezoceramic acoustic antenna. The structural scheme of the experimental setup is considered. It is shown that parallel connection of an external inductance to a piezoelectric element allows shifting the antiresonance frequency of an acoustic antenna, which leads to an increase in both the signal amplitude at the antenna output and an increase in the complex resistance module at the operating frequency.

Keywords: acoustic antenna, the sensitivity of the receiving antenna, the amplitude-frequency characteristic, the modulus of the complex resistance

The article considered the propagation of a long impulse signal in a hydroacoustic waveguide. A solution is given for a replica of a impulse signal in the second approximation of the dispersion theory. The propagation of a single-mode and multimode impulse in a Pekeris waveguide with a bottom in the form of an absorbing half-space is simulated. The acoustic properties of the half-space correspond to medium sand with an average grain size 0,3 mm. The result of the solution in the second approximation of the dispersion theory is compared with the result of the simulation of the impulse replica obtained as a convolution of the input signal with the impulse response of the waveguide. The disadvantages of the solution in the second approximation of the dispersion theory are shown and analyzed. It is shown that the theory of dispersion incorrectly reproduces the transients when the signal is switched on and off in cases where the signal frequency lies near the critical frequency of the first or second mode. It is shown that the theory of dispersion correctly reproduces the envelope of a multimode impulse signal.

Keywords: impulse signal, normal modes, group velocity, dispersion theory, intramode dispersion, intermode dispersion

This article deals with the parametric hydrophone antenna arrays the elements of which are connected in parallel on one coordinate (in the columns). The mathematical models had been developed which were derived from the formula of the directional characteristic of a right-angled flat radiator embedded into the absolutely hard baffle. A level of overshoots of the directional characteristic (as related to a principal maximum) amounts no more than 0.15; a coefficient of decreasing overshoots of the directional characteristics because of shifting lines is approximately equal to two 2 for the array (8 x 8 or 16 x 16) with a pitch equal to wave length, with shifting lines to half the array pitch, a gap between the elements is 0.1 of the array pitch and a direction of beams is from 5 to 18 degrees on both sides with respect to the normal to an antenna plane. Without the gap between the elements at the abovementioned conditions the overshoots and the coefficient of their decreasing will no more than 0.1 and approximately 2.4 respectively. Thanks to extending the antenna array pitch a number of antenna elements is being reduced, and consequently, a number of the power amplifiers will be reduced as well. The simulation results are presented including computed two-dimensional directional characteristics of the antennae. The overshoot dependences upon beam direction and antenna array element dimension are also shown.

Keywords: hydroacoustis parametric antenna array, narrow sector of scanning, parametric, antenna, nonlinear, element, array, array pitch, directional characteristic, overshoot, overshoot level, increasing of array pitch

Piezoceramics based on the lead zirconate-titanate (PZT) system is the basis of most transducers operating on the piezoelectric effect and are used in various electronic devices operating in the sections of electrical and hydroacoustics, ultrasonic technology, etc. In turn, piezoceramic materials created in the last century have substantially exhausted their potential for use in modern devices, and it is rather difficult to develop new compositions and is not economically efficient. In connection with the above, an urgent task is to find modern ways to increase the parameters of piezoceramic materials.

Keywords: piezoceramics, piezophase, piezomaterial, ceramic technology, microstructure

This article deals with the hydrophone antenna arrays (the results of studying are applicable to radio-frequency aerials as well) the elements of which are connected in parallel on one coordinate (in the columns). The mathematical models had been developed which were derived from the formula of the directional characteristic of a right-angled flat radiator embedded into the absolutely hard baffle. A level of overshoots of the directional characteristic (as related to a principal maximum) amounts approximately 0.3; a coefficient of decreasing overshoots of the directional characteristics because of shifting lines is approximately equal to 1.4 for the array (8 x 8 or 16 x 16) with a pitch equal to wave length, with shifting lines to half the array pitch, a gap between the elements is 0.1 of the array pitch and a direction of beams is not more than 15 degrees on both sides with respect to the normal to an antenna plane. Without the gap between the elements at the abovementioned conditions the overshoots and the coefficient of their decreasing will be approximately equal to 0.2 and 1.6 respectively. Thanks to extending the antenna array pitch a number of antenna elements is being reduced, and consequently, a number of the receiving channels and power amplifiers will be reduced as well. The simulation results are presented including computed two-dimensional directional characteristics of the antennae. The overshoot dependences upon beam direction and antenna array element dimension are also shown.

Keywords: antenna, element, array, array pitch, element pitch, directional characteristic, side-lobe level, narrow sector of scanning, increasing of array pitch

A hydroacoustic waveguide is considered as a linear system with parameters distributed over dis-tance. A method is proposed for modeling the impulse response of a waveguide. The fields of indi-vidual normal modes at fixed frequencies are calculated so that discretization theorems are satisfied. By performing the inverse Fourier transform of the fields of all modes separately, the time realiza-tions are restored. Then, summing the mode fields, the impulse response of the waveguide is calcu-lated. This approach allows you to "turn off" the fields of individual modes, add, if necessary, the fields of higher modes, or to study all fields separately, simulating the operation of mode selection. The impulse response is considered as a tool for solving the problems of inverting the acoustic characteristics of the seabed and modeling the propagation of signals in waveguides. The impulse response of the first mode of the Pekeris waveguide with the bottom in the form of an intermediate layer and half-space is restored, its wave attributes are revealed: ground wave, water wave, Airy wave. The frequency dependences of the group velocity of normal modes and the multimode im-pulse response are restored. Low-pass filtering of the impulse response makes it possible to reveal the Airy phase of the first mode.

Keywords: normal modes, seabed, attenuation coefficient, group velocity, impulse response, intramode dispersion, intermode dispersion

The article is devoted to the study of the adequacy of the model of a waveguide with a bottom in the form of half-space in broadband calculations of sound fields. Two bottom models are considered: liquid and porous. Two depths of the water layer are considered - units of meters and tens of meters. In the case of a liquid bottom, the speed of sound and the loss tangent in the bottom are considered to be frequency independent (model with a bottom with constant quality factor). In the case of a porous bottom, the frequency dependence of the speed of sound and the loss tangent is extracted from experimental data published in open sourses. The frequency dependences of the group velocities of the modes and modal attenuation coefficients are calculated. The frequency dependences of the group velocity of the first mode for the two waveguide models coincide, and the critical frequency of the normal modes changes in proportion to the depth of the water layer. The frequency dependences of the attenuation coefficient of normal modes turn out to be significantly different. The impulse response of shallow and deep-water waveguides are simulated. It is shown that in the case of a waveguide with a water layer depth of a few meters, the temporal structure of the impulsive field is indistinguishable - the bottom model without dispersion is adequate. In the case of a water layer depth of tens of meters, the temporal structure of the pulsed field for two bottom models is different - the waveguide model with a bottom without dispersion is inadequate.

Keywords: liquid bottom, porous bottom, marine sediments, dispersion of phase velocity, group velocity, intramode dispersion, intermode dispersion

An analytical representation of the velocity potential of a point source of sound is constructed for a model of a marine acoustic waveguide with a rigid stepped bottom, where a sound velocity profile varies with depth. Inhomogeneity of the bottom in the form of a cylindrical protrusion is modeled on the basis of the method of partial regions. The sound field is represented in the form of the sum of normal modes to construct the sound velocity potential in each partial region. The continuity of solutions at the boundary of partial regions leads to an infinite system of linear equations with respect to the coefficients under normal modes. In this work, formulas are obtained that describe the energy characteristics of the propagation of each of the normal modes along the waveguide. Examples of numerical modeling are given. An analysis of the excitation coefficients of normal modes is carried out for waveguide parameters are true to type of the Black Sea region.

Keywords: waveguide, normal modes, bottom inhomogeneity, excitation coefficient, partial regions, infinite system of linear equations, asymptotics

This article presents the results of a parameters study on a piezoelectric flexible transducer of a beam type. The analysis was performed by the finite element method using the ANSYS Multiphysics software package. It is shown that there are optimal parameters ratios of the structural elements of the transducer under study for which it is the most effective

Keywords: bending-type piezoelectric transducer, piezoelectric element, elastic plate, resonance frequency, conversion coefficient, Electromechanical coupling coefficient

The optoacoustic effect used for imaging can provide improved spatial resolution and temperature sensitivity compared to other methods of non-invasive cytometry, thermometry, used during thermal therapy for safe and effective diagnosis. However, the accuracy of the described optoacoustic methods is reduced due to biological variability and heterogeneous composition of tissues. Optoacoustic spectral analysis is used to assess the morphological changes of red blood cells (for example, size / shape).

Keywords: optoacoustics, optoacoustic signal, biofluid, oxygenation, hemoglobin, erythrocyte

An experimental study of the power amplifier in the frequency range 0.1-1 GHz. The amplitude and amplitude-frequency characteristics of the amplifier are obtained. The dependence of the second harmonic level of the useful signal on the input power is removed. It is shown that in the operating frequency range the gain is not less than 25 dB, and the upper limit of the linearity of the amplitude characteristic of the output is not less than 1 mW

Keywords: Transistor amplifier, ultra-high frequencies, amplitude response, amplitude-frequency response, upper limit of linearity of amplitude response, second harmonic

Hydroacoustic parametric monitoring and communication systems are considered. Brief description developed at the Department electrohydroacoustical and medical technology, Institute of nanotechnologies, electronics and instrumentation, southern Federal University (Agaimt INAP SFU) is the most promising sonar systems with parametric emitting antenna. Presented appearance and radiation pattern (days) of various embodiments of converters pumping parametricheskikh antennas of small-sized profiling. The design of composite Converter and parametric pumping days seysmoprofilografa. The description of the parametric side-view sonar and traverse-view sonar is given. In addition, parametric systems of hydroacoustic communication and monitoring of the sea on long routes are considered.

Keywords: hydroacoustic parametric system, parametric antenna, data transmission system, broadband antenna, water area monitoring, parametric profilograph. parametric navigation system, traversy overview

The method of local positioning of underwater vehicles by hydroacoustic system with linearly-frequency-modulated probing signals is considered. The method is based on measuring the range to the object and calculating the angles of arrival of echo signals on two or more spaced antennas. To increase energy and noise immunity signals with linear frequency modulation (LFM) are used. The scheme of towing an underwater vehicle with an acoustic beacon and the location of a hydroacoustic interferometer with two receiving antennas on a towing vessel are presented. The possibility of practical use of this method for high-precision measurement of the spatial position of an underwater towed or Autonomous vehicle relative to a surface vessel and, accordingly, the possibility of geographical reference of acoustic images and sea-bottom profilograms obtained by an underwater vehicle is experimentally shown. The results of full-scale tests of the experimental positioning system for its testing in the coastal zone of a small pond are presented. The block diagram of the local positioning equipment is presented. Examples of experimental distributions of the power module of echoes over the range are given for correlation processing of the acoustic beacon LFM signals. The paper also proposes the use of narrow-band traverse broadband parametric systems for communication between Autonomous unmanned underwater vehicles (ANPA) moving "in a flock". Describes the main specifications of the system and the experimentally measured in hydroacoustic basin of the directivity pattern of the antenna at the average rate of pumping and difference frequencies. The features of signal propagation in shallow sea are presented.

Keywords: hydroacoustic systems, side-view interferometric sonar, local positioning systems, parametric antenna, data transmission system, broadband antenna

The paper deals with the theoretical substantiation of the directional properties of the antenna arrays of a parametric profilograph intended for installation on an underwater uninhabited apparatus. A feature of such systems is the structural limitations of the overall dimensions of the carrier, which do not allow the antenna system to be implemented on the principles of linear hydroacoustics in the radiation mode. To solve this problem, we simulated the directional properties of the antenna arrays of the pump converter of a parametric profilograph. The directivity characteristics calculated for the center frequency of pumping in the diametral and traverse planes make it possible to take into account the expansion of the directivity of the radiating antenna when compensating for specified angles. The obtained values ​​of the estimation of the change in the directivity characteristic by the level of 0,7 make it possible to ensure the necessary axial concentration ratio of the radiating antenna of the profilograph for each of the working frequencies.

Keywords: parametric profilograph, bottom survey, pumping antenna, directional characteristic, scanning, side-lobe level

The paper deals with the optimization of characteristics and justification of the directional properties of the receiving antenna of a parametric profilograph. A feature of such systems is their performance in the form of a separate receiving channel, providing high sensitivity, the possibility of matching with the receiving-amplifier path and the best signal-to-noise ratio. In addition, the receiving antenna must provide for the required overall limitations the required angular resolution in the entire sector of the review. In solving these problems, the simulation was performed on the directional properties of the antenna receiving antenna. The issues of optimizing the layout of the antenna system and the use of cylinders on the transverse piezoelectric effect as elements of the receiving antenna are considered. The question of eliminating the influence of the thickness of the fill of the receiving antenna on the transparency coefficient is considered, which allows to ensure the necessary sensitivity of the receiving antenna.

Keywords: Kirichenko I. A.

Piezoceramic frames made of PKP-12 material with porosity up to 50% are made. The effect of the total, open and closed porosity on the properties of porous piezoelements on a given piezoelectric material is studied. Hydrostatic tests of porous piezoelements have been performed to determine the pressure at which irreversible changes occur.

Keywords: piezoceramics, PKP-12, piezocomposites, porous piezoceramics, piezoelectric materials, ferroelectrics, PZT, hydroacoustics, hydrophone

The method of control parameters of electro-acoustic transducers of the piezoelectric type, composed of an acoustic antenna arrays by electrical measurements is described. A convenient practical implementation of this method by determining the integral of active component of conductivity (area under curve) is proposed .

Keywords: acoustic antenna array, electro-acoustic transducer, piezoelectric element, control of parameters