The results of a study on the geometric shape of the damper on the efficiency of the ultrasonic piezoelectric transducer are presented. In particular, a damper in the form of a truncated cone is ...considered, the generatrix of which has an inclination angle α relative to the diameter of the piezoceramic plate. The shape of the damper in the form of a truncated cone is chosen based on the a priori assumption that this helps to increase the path of the wave in the damper material due to numerous reflections in it. A criterion for the efficiency of damper operation is proposed. The optimal (from the point of view of the damper efficiency) value of the angle α was determined theoretically and experimentally. The technology of its production is described. Satisfactory agreement between the results of theoretical and experimental studies was noted.
The influence of static compressional stress on the anisotropy of piezoelectric ceramics of BaTiO3 and PZT types is considered theoretically and experimentally. Static compression changes the domain ...structure of piezoceramics. These changes occur due to the reorientation of mostly 90° domain axes. As a result, all the parameters of the material change—elastic, piezoelectric, and dielectric. Some of them increase, and some, on the contrary, decrease. Changes occur in a nonlinear way, and higher-order parameters appear. The relationship between the total volume of the reoriented domains and the change in elastic moduli and piezomoduli is theoretically considered. The corresponding theoretical dependences are obtained. To confirm these theoretical dependences, experimental measurements were performed using the ultrasonic pulse-interference method at a frequency of 8 MHz. There is practically no oscillation movement of domain boundaries at this frequency, therefore, the change in the system of elastic and piezoelectric moduli is structural, not dynamic. The possibility of predicting changes in the structure of modules as a result of static compression is shown.
The paper presents the developed design of a combined electric baromembrane apparatus for the separation, concentration, and purification of industrial solutions and effluents. The separation of the ...solution is implemented in two stages: at the first stage, the solution passes through a flat-chamber module; at the second stage — through a tubular module, providing a high degree of solution purification. In addition, a procedure for calculating the separation area, the volume of the separated solution in the flat-chamber and tubular modules, as well as the volume of collectors for cathode and anode permeates of the tubular module, was developed. Calculations of the average permeability along the length of the membrane and the total electric power consumption for the separation of galvanic process solutions containing salts of heavy metals were performed.
Abstract
Piezoelectric transducers (PET) are widely used as emitters and receivers of acoustic signals to solve a great number of problems related to the study of the World Ocean. Providing the ...ability to operate the PET in the mode of short-sounding pulse radiation allows increasing the resolution of the remote sensing equipment of the aquatic environment. At the same time, a number of tasks require the use of non-directional emitters, for example, in the form of a thin-walled sphere. It is of interest to study the possibility of obtaining a short probing signal at the output of this type of PET. The paper considers the pulse mode of operation of a non-directional thin-walled spherical emitter excited by a short electrical signal. The research is based on the application of the method of equivalent circuits of the PET and the Fourier spectral method. The durations and amplitudes of the probing pulses emitted by the PEP are estimated. The results obtained may be applied to the design of equipment for underwater research.
The studies reported here demonstrate that short probe signals at the output of a narrow-band piezoelectric transducer plate (damperless) mounted on soft tissue can be obtained. Signals of ...a particular shape are applied to the piezoplate, which allows the duration of the probe pulses to be controlled.
The design of a flat-chamber electrobaromembrane apparatus for separating, concentrating, and purifying solutions and effluents in various industries has been updated. A distinctive feature of the ...updated design of the apparatus is cooling of the solution for separation in small separation chambers. A method has been developed to calculate the total volume of the solution being separated as well as the total volume of the apparatus body and its components, including the technological and design parameters of the cooling radiator, and to determine the mass of the structural materials for designing and constructing the apparatus. Comparative data showing the effectiveness of the developed design vis-à-vis the prototype is presented.
The solution of navigation problems the ice situation problems in the Arctic region need to study the acoustic parameters and local reflective properties of ice in real conditions. Information about ...the local sea ice acoustic properties essentially helps to solve the problems of statistical forecasting of reflective and scattering properties of ice cover. The successful solution of these problems mostly depends on the metrological parameters of the probing signals emitted by the primary piezoelectric transducers. This means, that to increase the resolution of the control and measuring equipment it is better to radiate and to receive short acoustic pulses. The article presents the results of analysis the pulse mode of operation of cylindrical piezoelectric transducers designed to measure the velocity of sound in sea ice. To reduce the length of acoustic pulses, an inductive-resistive load is connected to the electrical input of the radiator. The length and the amplitude of the emitted acoustic pulse were estimated using equivalent circuits of piezoelectric transducers and a spectral method based on the Fourier transforms. The optimal parameters of the electrical circuit, ensuring the minimum length of the acoustic pulses are calculated. The technique of possible measurements is described. The results are presented in the most general form, making possible to use them within different frequency ranges.
The main problem of creating computer-aided design systems (CAD) for press-forging processes is associated with a weak formalization of the subject area. An effective way for solving this problem is ...to provide the corresponding CAD with expert system properties when weakly structured knowledge is formalized in a certain way and transferred to the knowledge base. The paper describes the concept of developing a production knowledge base model of the computer-aided design system for solids of revolution press-forging. Some specific technological problems are examples of this model application in relation to tasks with point and interval solutions. The proposed concept of developing the knowledge base allows us to more formalize the subject area under consideration, to develop genetic algorithms for solving weakly structured problems of computer-aided forging process design, to ensure the work of appropriate programs without their adjustment to changing production conditions, and it can be used in other subject areas.
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