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Influence involving sewer overflow in general public health: A thorough scientometric investigation as well as organized evaluation.
Therefore, a towed platform equipped with wideband acoustics has several features that can be utilized for monitoring the mesopelagic dense scattering layers containing mixed species.In this article, the acoustic radiation force and torque exerted on a small spheroidal particle immersed in a nonviscous fluid inside an ideal cylindrical chamber is theoretically investigated. The ideal chamber comprises a hard top and bottom (rigid boundary condition) and a soft or hard lateral wall. By assuming that the particle is much smaller than the acoustic wavelength, analytical expressions of the radiation force and torque caused by an acoustic wave of arbitrary shape are presented. Unlike previous results, these expressions are given relative to a fixed laboratory frame. The model is showcased for analyzing the behavior of an elongated metallic microspheroid (with a 101 aspect ratio) in a half-wavelength acoustofluidic chamber with a diameter of a few millimeters. The results show that the radiation torque aligns the microspheroid along the nodal plane, and the radiation force causes a translational motion with a speed of up to one body length per second. Finally, the implications of this study on propelled nanorods by ultrasound are discussed.This paper proposes a sound field separation technique based on the time-domain equivalent source method with single layer pressure-velocity measurements to extract the nonstationary sound field radiated by the target source in a reverberant environment. This technique constructs a formulation that relates the pressures and particle velocities on a measurement surface to the strengths of time-domain equivalent sources arranged for modelling the outgoing and incoming waves. By solving the strengths of time-domain equivalent sources, the sounds coming from different sides of the measurement surface can be separated independently. In the proposed technique, the use of a time-domain equivalent source model allows the measurement surface to be arbitrarily shaped, thus providing the ability to analyze the arbitrarily shaped sources in a reverberant environment. Numerical simulations investigated the performance of the proposed technique when using different types of arrays, including planar, semi-cylindrical, and semi-spherical arrays, and an experiment with three loudspeakers located at two sides of the measurement surface was carried out to test the validity of the proposed technique. Both numerical and experimental results demonstrate that the proposed technique can remove the influence of disturbing sources in both time and space domains and separate out the target sound fields effectively.The radiation impulse response, which is the temporal Fourier transform of the radiation impedance, provides the basis for a convolution approach to evaluate the time-dependent force, instantaneous power, and energy transfer into the fluid resulting from a separable space-time normal velocity of a fluid loaded surface. After a brief review of the radiation impulse response approach to address such problems for planar radiators, several specific examples for planar radiators are addressed. General results for the temporal evolution of the energy from a baffled planar source of arbitrary shape with a specified space-time separable normal velocity distribution are developed. The case of a circular piston in an infinite rigid plane is then addressed to illustrate the time-dependent force, instantaneous power, and energy transfer into the fluid for pulsed velocity excitations. In particular, the energy exchange between the incompressible near field and the acoustic far field is addressed for the pulsed excitations.This study employs nonlinear ultrasonic techniques to track microstructural changes in additively manufactured metals. The second harmonic generation technique based on the transmission of Rayleigh surface waves is used to measure the acoustic nonlinearity parameter, β. Stainless steel specimens are made through three procedures traditional wrought manufacturing, laser-powder bed fusion, and laser engineered net shaping. The β parameter is measured through successive steps of an annealing heat treatment intended to decrease dislocation density. selleck inhibitor Dislocation density is known to be sensitive to manufacturing variables. In agreement with fundamental material models for the dislocation-acoustic nonlinearity relationship in the second harmonic generation, β drops in each specimen throughout the heat treatment before recrystallization. Geometrically necessary dislocations (GNDs) are measured from electron back-scatter diffraction as a quantitative indicator of dislocations; average GND density and β are found to have a statistical correlation coefficient of 0.852 showing the sensitivity of β to dislocations in additively manufactured metals. Moreover, β shows an excellent correlation with hardness, which is a measure of the macroscopic effect of dislocations.In the linear regime and in the absence of mean flow, the impedance of perforated liners is driven by visco-thermal effects. In this paper, two numerical models are employed for predicting these visco-thermal losses. The first model is the linearized compressible Navier-Stokes equations (LNSE), solved in the frequency domain. The second model is the Helmholtz equation with a visco-thermal boundary condition, accounting for the influence of the acoustic boundary layers. These models are compared and validated against measurements. The quantitative analysis of the dissipation rate due to viscosity, computed from the LNSE solutions of four perforated plates, highlights significant differences between the edge effects of a macro- and a micro-perforated plate. In the latter case, a jet is present at the entrances of the perforation. In contrast, the proposed numerical method to calculate the impedance of perforated liners, based on the Helmholtz equation and a visco-thermal boundary condition, is found to be computationally cheaper and to provide reliable predictions.An experimental concept for measuring sound-sound scattering of finite aperture acoustic beams in a water tank facility is presented. In order to achieve a measurable effect, the beams are collimated within their intersection domain by a focusing acoustic lens. A paraxial quasi-linear split step simulation tool has been developed and used in order to determine and optimize experiment setup parameters. The scattered part of the difference frequency field was measured and found to be compatible with simulations. Furthermore, the primary beams were also monitored in order to guarantee full compatibility with simulated propagation and compare the measured difference field with the overlap contribution. A spatially coherent post processing filtering was applied in order to improve the signal to noise ratio. A distinct clear scattering peak in the difference field has been identified propagating with the predicted off axis tilt angle.
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