Analysis of Directional Properties of Angular Horn Antenna

In this paper, horn antennas are considered to belong to the class of aperture antennas which usually include a sound wave reflector and an electroacoustic transducer. For the variant of technical implementation of the electroacoustic transducer in the form of a corner antenna, the problem of sound emission by such an antenna is solved . taking into account the repeated reflection of emitted sound waves from the antenna design elements. The study of the acoustic properties of such an antenna was carried out taking into account a number of assumptions. 'what material, the thickness of the walls of the mouthpiece is infinitesimal. These conditions are supplemented by the known conditions of radiation at infinity. All the above assumptions make it possible to greatly simplify the solution of the problem of sound radiation by an angular horn antenna. To do this, the Helmholtz equation under boundary conditions was solved by the method of connected fields in multiconnected domains, corresponding to the physical model of the antenna. The radiation field of such an antenna is presented in the form of three partial regions, which in turn, according to the method of partial regions - in the form of Fourier series expansions, the coefficients of which are determined by solving differential equations describing piezoceramic transducer oscillations and wave processes. in acoustic environments in contact with it. The solution of the Helmholtz equation is reduced to the solution of an infinite system of linear algebraic equations taking into account the above assumptions, as well as the conditions of field continuity at the boundary of partial domains, we obtain an infinite system of linear algebraic equations. Based on the system, an approximate expression for the normalized radiation pattern is obtained. Studying the features of the directional properties of the angular antenna by direct analysis of the expression is not possible. Therefore, such a study was carried out on the basis of calculated directivity diagrams obtained using a computer for a wide range of wave sizes and geometrical characteristics of the angular antenna. cylindrical electroacoustic transducers. In all calculations, a uniform distribution of the oscillating velocity on the surface of the emitter was chosen Analyzing the obtained data, there is a pronounced dependence of the shape of the pattern on the magnitude of the wave size of the speaker. This is manifested in the fact that the main petal splits into two or even three petals, as well as in increasing the overall sharpness of the pattern.

Use of the pass-through method to solve sound radiation problems of a spherical electro-elastic source of zero order

In the article was solved the problem of radiation of a sound by the electroacoustic transducer which is executed in the form of a thin spherical cover, using a pass-through method. The outer and inner surfaces of the shell are completely electroded. The application of this method provides an opportunity to avoid inaccuracies that arise during the traditional formulation of boundary conditions for acoustic mechanical fields, the use of equivalent substitution schemes and the absence of boundary conditions for the electric field in general. Given methodology eliminates these shortcomings by applying conjugation conditions, taking into account the types of electroding of the surfaces of piezoceramic transducers, the introduction of boundary conditions for current and voltage. The results of the solution demonstrate the high capabilities of this pass-through method, in terms of taking into account the peculiarities of determining the characteristics of these fields, values and dependences of the main complex characteristics of the electroelastic transducer, and auxiliary material constants of the piezoelectric material. The proposed approach is relevant, because it allows to increase the reliability of modeling the operating conditions of acoustic transducers in the context of wave problems of acoustics. Aim is to enhance the range of performances and build algorithms solving problems of stationary mode hydroelectroelasticity sound radiation. The expected results are presented in terms of improving approaches to studying the features of the oscillatory process of the active elements of sound-emitting systems and the accompanying effects of the transformation of interconnected fields involved in the formation of the acoustic signal in the liquid

Shifting the operating frequency of the piezoceramic electroacoustic transducer langevin type using passive cooling methods

The object of research: the shift of resonant frequency of the piezoceramic electroacoustic transducer Langevin type depending on the shape of the back plate. Investigated problem: the relationship between changes in shape of back plate of the Langevin type transducer with the resonant frequency of the oscillating system. Search quantitative contribution to shift the resonant frequency of each of the modifications: shape, diameter, thickness, weight of back plate. The main scientific results: vibration modes of a transducer with a back plate with horizontal and vertical radiator ribs were obtained. The graphs of the shift resonant frequency depending on the change in the diameter and thickness of the back tail with vertical radiator ribs are presented. It is established, that the change in the thickness and diameter of the back plate of the transducer effects on resonance frequency much less than the change in mass. The area of practical use of the research results: designing piezoceramic electroacoustic transducer with passive cooling method. Innovative technological product: guidelines for choosing the shape changes back plates of the Langevin type transducer for decreasing heating temperature, with keeping resonant frequency. Scope of the innovative technological product: scope of application of the Langevin type transducer: underwater acoustics, ultrasonic technological equipment, ultrasonic engine, piezotransformer, medical equipment, rock drilling devices.

Investigation of the Possibility of Applying a Genetic Algorithm for Electroacoustics Problems

This paper considers the adaptation and application of a genetic algorithm to find the parameters of the electrodynamic transducer model. The advantages and disadvantages of this method in comparison with the classical method of identification using added mass are considered. The derivation of the suitability function for estimating the identified parameters is presented, which can also be used to identify other types of electroacoustic transducers. The theory underlying genetic algorithms has been examined and shown how genetic algorithms work by assembling the best solutions from small structural elements with excellent qualities. Next, the differences between genetic and traditional algorithms were analyzed, including population population support and the use of genetic representation of solutions. After that, the strengths of genetic algorithms were described, including the possibility of global optimization and applicability to problems with complex mathematical representation or without representation at all, and noise resistance. Disadvantages were also highlighted: the need for special definitions and settings of hyperparameters, the danger of premature convergence. In conclusion, the situations when the use of genetic algorithms are listed This algorithm is not tied to a specific engineering or scientific field, which makes it universal, it is equally used in genetics and computer science. The parameters were determined using a genetic algorithm and compared with the more classical method of added mass for acoustics. The comparative table in the work illustrates the high accuracy of the genetic algorithm in comparison with the method of added mass. During the work on the practical part, also to improve the behavior of the model at frequencies higher than the resonant, it was decided to complicate the model of the electrical subsystem of the tranducer and introduce additional parameters: parallel resistance and parallel inductance. As a result, the complicated model began to correspond better to the measured values in the entire frequency domain, and is therefore more accurate. This is an example of the convenience of using a genetic algorithm in the transition from identification of one model with specific parameters to another. The results of this work prove that the use of a genetic algorithm is appropriate for solving electroacoustic problems because its application allows to quickly experiment and identify more complex models for which the added mass method can not be applied. Also, in the future, genetic algorithm can be used to identify transducer models of in time domain, for example, nonlinear models of electrodynamic transducers or models in a state space, which is the subject of future research.This paper considers the adaptation and application of a genetic algorithm to find the parameters of the electrodynamic transducer model. The advantages and disadvantages of this method in comparison with the classical method of identification using added mass and the method of parameter selection BL are considered. The derivation of the fitness function for assessing the quality of the identified parameters is presented, which can also be used to identify other types of electroacoustic transducers. The directly measured values ​​for the application of the algorithm are the voltage at the terminals of the converter, the current through the coil of the converter and the displacement of the moving part of the converter. The undoubted advantage of the genetic algorithm compared to classical identification methods is its versatility and the ability to quickly adapt and configure for research and experimentation with different models and different types of transducers used in acoustics. This article describes the adaptation and application of a genetic algorithm to find parameters of an electrodynamic transducer model. The advantages and disadvantages of this method in comparison with the classical identification method using added mass are considered. The derivation of the fitness function for assessing quality of the identified parameters is presented, which can also be used to identify other types of electroacoustic transducer models.

ELECTROPHORESIS IN THE TOTAL (CONSTANT AND ALTERNATING) ELECTRIC FIELD. II. PECULIARITIES OF THE COMBINED IMPACT OF ALTERNATING AND CONSTANT ELECTRIC FIELDS

The hydrodynamics of electrophoresis under the simultaneous impact of constant and alternating electric fields is considered. It has been shown that when the constant and alternating external fields are combined, the energy of the constant electric field is transferred into the alternating hydrodynamic field. An example is given of a dispersed medium in which a giant dispersion of the dielectric constant can arise, which in turn can contribute to an increase in the total electrophoresis rate. Analogies of the behavior of the considered dispersed medium with the action of an electroacoustic transducer based on the use of electrokinetic phenomena are given.

Application of Wavelet Transform to Damage Identification in the Steel Structure Elements

This work concerns the concept and verification of the experimental possibility of using a wavelet transform to assess a steel structure’s condition. In the research, a developed measuring stand was used. Mechanical waves in the metal plate were excited by the impact. These waves were recorded with an electroacoustic transducer and registered in the form of electrical signals. Both the signals generated by the actuator of the plate and the signals reaching the transducer were recorded. The registered data were decomposed into wavelet coefficients. Laboratory tests have shown the possibility of applying this type of test to identify damage in steel structural elements—the relationship between the details of the wavelet transform and the type of damage was demonstrated.

Development of piezoceramic electroacoustic transducers for acoustic devices with a sound pressure of 125 dB or more

The increased sound pressure level of piezoceramic electroacoustic transducers is important for acoustic devices designed to create high-intensity sound, 125 decibels or more. This is especially true of acoustic devices that use a group of transducers. An electroacoustic transducer that develops a higher sound pressure can greatly reduce the number of radiating elements in an acoustic device. In the performed work electroacoustic transducers are created that capable to develop sound pressure level up to 125 dB. The article presents the results of the development of electroacoustic transducers for three frequency versions. The scheme of the generator of the exciting voltage for electroacoustic converters with the raised sound pressure is offered and investigated. The result is particularly relevant when used in multi-element sound-emitting devices, as repeatedly reduces the required number of converters to achieve the same result.

Research on the Cascade-Connected Transducer with Multi-Segment Used in the Acoustic Telemetry System while Drilling

The electroacoustic transducer with the performances of low frequency, small size, and high power is desired in the application of the acoustic telemetry system while drilling. In order to fulfill the severe requirements, a novel cascade-connected transducer with multi-segment is developed. The essential framework of such a transducer is to add the cross-beams in the multi-segment cascade-connected arrangement, based on the fundamental configuration of the longitudinal transducer. The flexural vibrations of cross-beams help the transducer to present the appropriate coupling between longitudinal and flexural vibrations, which provide many benefits in keeping the advantages of the longitudinal transducer and lowering the resonance frequency. It is the finite element method to be used for simulating the mode shapes of the cascade-connected transducer, especially the behavior of the cross-beams, and some performances of transducer are also predicted. Several prototypes of cascade-connected transducers with different segments are manufactured. Their related tests show a good agreement with the finite element simulations and analyses. Their characteristics of low frequency, small size, light weight, and high power are attractive for the transmitting or receiving application in the acoustic telemetry system while drilling.

Measurement of impedance and sensitivity of electroacoustic transducers

In the paper a methodology is presented for electroacoustic transducer impedance and transmitting sensitivity measurement. Loaded transducer electrical impedance is measured in water test tank. The methodology for measurement of transmitting sensitivity is based on the pulse method. Experimental results are presented for measured impedance and sensitivity of piezoceramic disc transducer in water filled test tank.