The homotopy analysis method (HAM) is employed to propose a highly
accurate technique for solving strongly nonlinear aeroelastic systems of airfoils in
subsonic flow. The frequencies and amplitudes of limit cycle oscillations (LCOs)
arising in the considered systems are expanded as series of an embedding parameter.
A series of algebraic equations are then derived, which determine the coefficients of
the series. Importantly, all these equations are linear except the first one. Using some
routine procedures to deduce these equations, an obstacle would arise in expanding
some fractional functions as series in the embedding parameter. To this end, an
approach is proposed for the expansion of fractional function. This provides us with a
simple yet efficient iteration scheme to seek very-high-order approximations.
Numerical examples show that the HAM solutions are obtained very precisely. At the
same time, the CPU time needed can be significantly reduced by using the presented
approach rather than by the usual procedure in expanding fractional functions.

Y. P. Zhang

Y. M. Chen

J. K. Liu

G. Meng

Highly Accurate Solution of Limit Cycle Oscillation of an Airfoil in Subsonic Flow

The aim of this work is to present the great performance of the numerical algorithm of Particle Swarm Optimization applied to find the best teeth modifications for multimesh helical gears, which are crucial for the static transmission error (STE). Indeed, STE fluctuation is the main source of vibrations and noise radiated by the geared transmission system. The microgeometrical parameters studied for each toothed wheel are the crowning, tip reliefs and start diameters for these reliefs. Minimization of added up STE amplitudes on the idler gear of a three-gear cascade is then performed using the Particle Swarm Optimization. Finally, robustness of the solutions towards manufacturing errors and applied torque is analyzed by the Particle Swarm algorithm to access to the deterioration capacity of the tested solution.

Alexandre Carbonelli

Jo&#235;l Perret-Liaudet

Emmanuel Rigaud

Alain Le Bot

Particle Swarm Optimization as an Efficient Computational Method in order to Minimize Vibrations of Multimesh Gears Transmission

New designs of high-resolution ultrasonic imaging systems that operate in the 30&#x2013;100&#x2009;MHz
region, for example, those based on linear transducer systems, are currently being investigated for
medical purposes. Acoustic waves with frequencies in this range can detect microscopic
structures in human tissue but will typically only penetrate a few mm because of large
attenuation. However, this is sufficient for a diagnostic ultrasound scan of human skin. 
The signal-to-noise ratio and the focusing properties of the scanner are critical factors in
dermatology, which are determined by the transducer design. 
A linear pulsed PVDF transducer array with a center frequency around 45&#x2009;MHz is studied
by applying numerical simulations, based on the finite element method (FEM), of this
electromechanical system. Tx-beamforming properties of linear arrays with one, three, five,
and seven active elements are investigated at different depths. The image quality obtained
from synthetic Rx-beamforming, using responses from five electrodes, is estimated from
reconstructed images of 25&#x2013;100&#x2009;<svg style="vertical-align:-2.05875pt;width:8.6625004px;" id="M1" height="8.6875" version="1.1" viewBox="0 0 8.6625004 8.6875" width="8.6625004"  xmlns="http://www.w3.org/2000/svg">
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images are found to be similar with the Tx-beamforming resolution parameters estimated
from the time-derivative of the pressure beams.

Eivind Brodal

Frank Melands&#248;

Svein Jacobsen

Performance of an Ultrasonic Imaging System Based on a 45-MHz Linear PVDF Transducer Array: A Numerical Study

Efficient identification and control algorithms are needed, when active vibration suppression techniques are developed for industrial machines. In the paper a new actuator for reducing rotor vibrations in electrical machines is investigated. Model-based control is needed in designing the algorithm for voltage input, and therefore proper models for the actuator must be available. In addition to the traditional prediction error method a new knowledge-based Artificial Fish-Swarm optimization algorithm (AFA) with crossover, CAFAC, is proposed to identify the parameters in the new model. Then, in order to obtain a fast convergence of the algorithm in the case of a 30&#x2009;kW two-pole squirrel cage induction motor, we combine the CAFAC and Particle Swarm Optimization (PSO) to identify parameters of the machine to construct a linear time-invariant(LTI) state-space model. Besides that, the prediction error method (PEM) is also employed to identify the induction motor to produce a black box model with correspondence to input-output measurements.

Ying Wu

Sami Kiviluoto

Kai Zenger

X. Z. Gao

Xianlin Huang

Hybrid Swarm Algorithms for Parameter Identification of an Actuator Model in an Electrical Machine

A nonlinear time-varying (NLTV) dynamic model of a hypoid gear pair system with time-dependent mesh point, line-of-action vector, mesh stiffness, mesh damping, and backlash nonlinearity is formulated to analyze the transitional phase between nonlinear jump phenomenon and linear response. It is found that the classical jump discontinuity will occur if the dynamic mesh force exceeds the mean value of tooth mesh force. On the other hand, the propensity for the gear response to jump disappears when the dynamic mesh force is lower than the mean mesh force. Furthermore, the dynamic analysis is able to distinguish the specific tooth impact types from analyzing the behaviors of the dynamic mesh force. The proposed theory is general and also applicable to high-speed spur, helical and spiral bevel gears even though those types of gears are not the primary focus of this paper.

Jun Wang

Teik C. Lim

On the Boundary between Nonlinear Jump Phenomenon and Linear Response of Hypoid Gear Dynamics

Detection, classification, and tracking of small vessels are important tasks for improving port security and the security of coastal and offshore operations. Hydroacoustic sensors can be applied for the detection of noise generated by vessels, and this noise can be used for vessel detection, classification, and tracking. This paper presents recent improvements aimed at the measurement and separation of ship DEMON (Detection of Envelope Modulation on Noise) DEMON acoustic signatures in busy harbor conditions. Ship signature measurements were conducted in the Hudson River and NY Harbor. The DEMON spectra demonstrated much better temporal stability compared with the full ship spectra and were measured at distances up to 7&#x2009;km. The combination of cross-correlation and methods allowed separation of the acoustic signatures of ships in busy urban environments.

Kil Woo Chung

Alexander Sutin

Alexander Sedunov

Michael Bruno

DEMON Acoustic Ship Signature Measurements in an Urban Harbor

Exposure to whole-body vibration (WBV) is associated with a wide variety of health disorders and as a result WBV levels are frequently assessed. Literature outlining WBV accelerations rarely address the calibration techniques and procedures used for WBV sensors to any depth, nor are any detailed information provided regarding such procedures or sensor calibration ranges. The purpose of this paper is to describe a calibration method for a 6 DOF transducer using a hexapod robot. Also described is a separate motion capture technique used to verify the calibration for acceleration values obtained which were outside the robot calibration range in order to include an acceptable calibration range for WBV environments. The sensor calibrated in this study used linear (<svg     style="vertical-align:-0.1638pt;width:57.962502px;" id="M1" height="11.375" version="1.1" viewBox="0 0 57.962502 11.375" width="57.962502"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
    
        
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</svg> values greater than 0.97 for maximum and minimum acceleration amplitudes of up to &#xb1;8&#x2009;m/s<sup  >2</sup> and maximum and minimum velocity amplitudes up to &#xb1;100&#xb0;/s. The motion capture technique verified that the translational calibrations held for accelerations up to &#xb1;4&#x2009;g. Thus, the calibration procedures were shown to calibrate the sensor through the expected range for 6-DOF WBV field measurements for off-road vehicles even when subjected to shocks as a result of high speed travel over rough terrain.

Sarah Cation

Michele Oliver

Robert Joel Jack

James P. Dickey

Natasha Lee Shee

Whole-Body Vibration Sensor Calibration Using a Six-Degree of Freedom Robot

A theoretical basis for the scaling of broadband shock noise intensity in supersonic jets was formulated considering linear shock-shear wave interaction. Modeling of broadband shock noise with the aid of shock-turbulence interaction with special reference to linear theories is briefly reviewed. A hypothesis has been postulated that the peak angle of incidence (closer to the critical angle) for the shear wave primarily governs the generation of sound in the interaction process with the noise generation contribution from off-peak incident angles being relatively unimportant. The proposed hypothesis satisfactorily explains the well-known scaling law for the broadband shock-associated noise in supersonic jets.

Max Kandula

A Theoretical Basis for the Scaling Law of Broadband Shock Noise Intensity in Supersonic Jets

In a fluid-saturated porous formation, acoustics and electromagnetic waves are coupled based on Pride seismoelectric theory. An exact treatment of the nonaxisymmetric seismoelectric field excited by acoustic multipole sources is presented. The frequency wavenumber domain representations of the acoustic field and associated seismoelectric field due to acoustic multipole sources are formulated. The full waveforms of acoustic waves and electric and magnetic fields in the time domain propagation in borehole are simulated by using discrete wave number integration, and frequency versus axial-wave number responses are presented and analyzed.

Zhiwen Cui

Jinxia Liu

Yujun Zhang

Kexie Wang

Hengshan Hu

Simulation of Monopole and Multipole Seismoelectric Logging

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<p><em>Advances in Acoustics and Vibration</em> acts as a forum for the dissemination of innovative and original research and development work in the area of acoustics and vibration.</p>


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Advances in Acoustics and Vibration ceased publication in 2019 and is no longer accepting submissions.

description

Advances in Acoustics and Vibration acts as a forum for the dissemination of innovative and original research and development work in the area of acoustics and vibration.

Advances in Acoustics and Vibration