J. M. Stauber , B. A. Marmo ,
 Xi Engineering Ltd, Edinburgh, United Kingdom
Tonal noise from wind turbines can have effects on neighboring residences and its emission can result in strong regulatory penalties that can include the closure of wind farms. The authors present a model of a new broadband damping approach where containers filled with EniDamp™, an Advance Particle Damping (APD) material. The containers, so-called APD pods, are magnetically fixed to wind ...
Direction of Arrival (DoA) Performance of Several Acoustic Vector-Sensor Configurations in the Reverberant Environment
M. Wajid , A. Kumar , R. Bahl ,
 Indian Institute of Technology Delhi, Delhi, India.
Several acoustic vector-sensor (AVS) configurations have been tested for direction of arrival (DoA) estimation in a diffused reverberant environment using pressure gradient method. The discrete pressure sensors have been arranged with different geometrical placement and pressure gradients have been estimated for finding DoA of an acoustic source. The received signals at the pressure sensor for ...
G. Campa, and S.M. Camporeale
Politecnico di Bari, Bari, Italy
The Transfer Matrix method in the Acoustics Module of COMSOL Multiphysics is used when the whole system can be represented into a sequence of subsystems that interact only with adjacent subsystems. This method is frequently used in mathematics and, particularly, in acoustics. The application of the present method is really useful, because it permits to break the total system into a network of ...
University of the West of Scotland, Paisley, Renfrewshire, UK
The Jecklin Disk is a sound absorbing disk placed between two omnidirectional microphones. It is used to recreate some of the frequency-response, time and amplitude variations human listeners’ experience, but in such a way that the recordings also produce a useable stereo image through loudspeakers. This paper presents a finite element model able to simulate the effects on sound propagation ...
F. J. Navarro-Brull , P. Poveda , J. Ramis , R. Gómez ,
 Departament de Química Física, Universidad de Alicante, Alicante, Spain
 Departament de Física, Enginyeria de Sistemes i Teoria del Senyal, Universidad de Alicante, Alicante, Spain
Possible drawbacks of microreactors are inefficient reactant mixing due to the predominance of laminar flow and clogging (when solid-forming reactions are performed or solid catalyst suspensions are used). Ultrasound has been successfully implemented not only to prevent these problems but also for its well-known mixing and particle-dispersion effects. Several configurations have been used for ...
屈治国 , 张秀海 ,
引言 超材料是一类具有天然材料所不具备的特殊性质的材料[1-3]。近年来，有学者开始研究超材料对波的旋转效应，这一研究有着工程应用价值。江雪等设计并实验验证了一种声场旋转器。江雪等进一步研究了声场旋转器整体尺寸大小对其工作带宽的影响及声场旋转器中心处的旋转角度与其结构单元长度的关系。但未见声场旋转器结构单元尺寸对其工作带宽影响的研究。 COMSOL Multiphysics® 的使用 采用 COMSOL Multiphysics® 的声学模块和结构力学模块模拟图1的俯视二维结构，采用完美匹配层以获得更好的模拟结果。 结果 本文模拟了5个声场旋转器在不同频率下的声场，发现随着长方体结构单元长宽比的增加，尽管声场旋转器在低频仍能工作，但可以工作的高频频率是下降的，即声场旋转器的工作带宽是变窄的。为了确定声场旋转器的高频工作截止频率，本文采用二分法确定声场旋转器 ...
S. Floody, R. Venegas, and F. Leighton
Universidad de Chile, Facultad de Artes, Departamento de Música y Sonología, Licenciatura en Sonido, Santiago, Chile
University of Salford, Acoustics Research Centre, Salford, UK
Universidad Tecnológica de Chile Inacap, Sede Pérez Rosales, Santiago, Chile
The present article presents a method to redistribute the acoustic modes of a rectangular enclosure in the low frequency range using slit resonators. The objective of the present work is to compare different strategies of optimal design in order to determine the dimensions of the resonators. The method of the finite elements will be used to model the acoustic physical behavior of the room. In ...
H. Lissek, R. Boulandet, and M. Maugard
Ecole Polytechnique Federale de Lausanne
An \"electroacoustic absorber\" is a loudspeaker, used as an absorber of sound, which acoustic impedance can be varied by electrical means. This can be achieved either by plugging passive shunt electric networks at the loudspeaker terminals (“shunt loudspeakers”) or by feeding back the loudspeaker with a voltage proportional to acoustic quantities, such as sound pressure and diaphragm normal ...
COMSOL Multiphysics® Software for Simulation of Surface Response to Excitation Method for Manufacturing Process Performance Monitoring - new
H. Fekrmandi, N. Miniello, R. Kiflemariam, I. Nur Tansel
Mechanical & Materials Engineering Department, Florida International University, Miami, FL, USA
In this study, COMSOL Multiphysics® software was used to simulate the surface response to excitation method (SuRE). An aluminum beam with a piezoelectric element bonded is modeled using the COMSOL Acoustics Module. A frequency domain sweep study was performed to simulate the sweep sign generation. The frequency spectrum of the structure is monitored through a frequency range of (20kHz-400kHz). A ...
Application of a Weakly Non-Linear Analysis to the Analysis of Thermoacoustic Combustion Instabilities - new
D. Laera, S. M. Camporeale, G. Campa
Politecnico di Bari, Bari, Italy
Ansaldo Energia, Genoa, Italy
The thermoacoustic combustion instabilities are complex phenomena that may occur in steady flow combustion systems that are aboard of, e.g., rocket engines or gas turbines. The phenomena involve the interaction of chemical reactions with fluid-dynamic and propagation of pressure waves in the combustion chamber. Combustion instabilities may lead to a stable condition (known as “limit-cycle”) ...