Acoustical Physics最新文献

This paper presents a method for rapidly reverse designing the absorption performance of acoustic coatings, utilizing the principles of a concatenated deep neural network. It enables the swift acquisition of effective input parameters. By cascading a reverse neural network with pre-trained forward neural networks, a concatenated neural network is obtained. This network maps the absorption spectrum response to structural and material parameters, thereby resolving the nonuniqueness issue in traditional reverse design. The paper describes the detailed process of reverse designing the absorption performance of acoustic coatings and validates the correctness of the reverse design using finite element methods. A comparative analysis investigates the impact of different loss functions on result accuracy. The findings demonstrate that the proposed modified loss function algorithm significantly enhances precision compared to traditional direct reverse design. This advancement allows for the customization of acoustic coatings with specific acoustic properties, providing technical groundwork for vibration and noise reduction in underwater vehicles.

An acoustic delay line consisting of two Y–X-cut lithium niobate plates 0.2 mm thick placed on top of each other was experimentally investigated. An interdigital transducer is located at the edge of each plate. An rf voltage (pulsed or continuous-wave) is fed to one transducer, which excites a piezoelectrically active acoustic wave with transverse–horizontal polarization propagating in the first plate. The electric field of this wave penetrates the second plate to excite an acoustic wave therein, which is converted into an electrical signal using the second interdigital transducer. The phase and delay time of the output signal can be changed by varying the distance between the transducers by shifting one plate relative to the other.

Acoustic levitation is an interesting technique used for levitating small objects/materials using sound waves. In this study, lateral movement of levitating particles is demonstrated experimentally and numerically. The method can simultaneously move multiple particles and the paper demonstrates levitation for three particles. Initially, an ultrasonic tweezer with a resonance frequency of 40 kHz is used to levitate three particles of average weight of 0.15 mg each. The experimental design is based on numerical simulation. Further, the levitated particles are moved in a lateral direction using two ultrasonic tweezers setup by manipulating the phase of one of the tweezers using Arduino Nano. As evident by simulations, the movement takes place due to the interference of waves leading to the movement of pressure node. The lateral movement of particles can be controlled and even reversed by changing the phase difference.

The acoustic and electrical properties of a 128-element ultrasonic transducer designed to generate high-intensity focused ultrasound in air in the low-frequency ultrasonic range are investigated. To reduce parasitic grating maxima of the acoustic field, a spiral arrangement of piezoelectric elements on a spherical base was used. The operating frequency of the transducer was 35.5 kHz, and the diameter of the source and focal length were approximately 50 cm, significantly exceeding the wavelength (approximately 1 cm). This selection of parameters allowed for effective focusing, with localization of wave energy in a small focal region, thereby achieving extremely high levels of ultrasonic intensity. The parameters of the ultrasonic field were studied using a combined approach that included microphone recording of the acoustic pressure and measuring the acoustic radiation force acting on a conical reflector. Acoustic source parameters were determined from the two-dimensional spatial distribution of the acoustic pressure waveform, which was measured by scanning the microphone in a transverse plane in front of the source. Numerical modeling of nonlinear wave propagation was also used based on the Westervelt equation to simulate the behavior of intense waves. The acoustic pressure level reached 173 dB, with a focal spot size comparable to the wavelength.

The self-contained vertical acoustic–hydrophysical measuring systems Mollyusk-19 and Mollyusk-21 were developed to study spatiotemporal inhomogeneities in the sound field velocity and in modal structures of low-frequency sound fields and internal waves. This paper describes the circuit, structural, and software solutions for the main problem posed when developing new systems to improve their performance characteristics. The possibilities of applying these systems to solve the formulated problems was illustrated by the results of field measurements on the Posiet Bay shelf in the Sea of Japan.