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C. E. Wallace

Bio: C. E. Wallace is an academic researcher. The author has contributed to research in topics: Wavenumber & Radiation resistance. The author has an hindex of 1, co-authored 1 publications receiving 357 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, the authors derived the radiation resistance of a finite rectangular panel from the total energy radiated to the far field, assuming that the panel is assumed to be supported in an infinite baffle.
Abstract: The radiation resistance corresponding to the natural modes of a finite rectangular panel is theoretically determined from the total energy radiated to the farfield. The panel is assumed to be simply supported in an infinite baffle. Asymptotic solutions for the low‐frequency region are derived, and curves covering the entire frequency range for various mode shapes and aspect ratios are obtained through numerical integration. When the ratio of the acoustic wavenumber to the panel wavenumber is a constant much less than unity, the radiation resistance for all modes is a minimum if the intranodal area (the area between adjacent node lines) is square, and increases with the aspect ratio of the intranodal area.

383 citations


Cited by
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TL;DR: In this article, the authors compared two different formulations for calculating the total acoustic power radiated by a structure, in terms of the amplitudes of the structural modes and the velocities of an array of elemental radiators on the surface of the structure.
Abstract: Two formulations for calculating the total acoustic power radiated by a structure are compared; in terms of the amplitudes of the structural modes and in terms of the velocities of an array of elemental radiators on the surface of the structure. In both cases, the sound radiation due to the vibration of one structural mode or element is dependent on the vibration of other structural modes or elements. Either of these formulations can be used to describe the sound power radiation in terms of a set of velocity distributions on the structure whose sound power radiation is independent of the amplitudes of the other velocity distributions. These velocity distributions are termed ‘‘radiation modes.’’ Examples of the shapes and radiation efficiencies of these radiation modes are discussed in the cases of a baffled beam and a baffled panel. The implications of this formulation for the active control of sound radiation from structures are discussed. In particular, the radiation mode formulation can be used to provide an estimate of the number of independent parameters of the structural response which need to be measured and controlled to give a required attenuation of the radiated sound power.

391 citations

Journal ArticleDOI
TL;DR: In this article, the authors developed effective, general methods for sizing optimization of acoustically radiating structures using mathematical programming techniques, and used the CONMIN optimization program to find the optimal thickness distribution of flat plates with clamped edges.

106 citations

Journal ArticleDOI
TL;DR: The authors reviewed the most significant works in literature about the acoustic behaviour of sandwich panels, starting from the first examples of multi-layered structures, comprising a series of different dif...
Abstract: This paper reviews the most significant works in literature about the acoustic behaviour of sandwich panels, starting from the first examples of multi-layered structures, comprising a series of dif...

101 citations

Journal ArticleDOI
TL;DR: In this paper, the average radiation efficiency of point-excited rectangular plates, including those with a very large aspect ratio (strips), was investigated by using a modal summation method based on the farfield sound intensity.

99 citations

Journal ArticleDOI
TL;DR: This paper describes a correction and an extension in the previously published large signal equivalent circuit model for a circular capacitive micromachined ultrasonic transducer (CMUT) cell that is able to predict the entire behavior of CMUT until the membrane touches the substrate.
Abstract: This paper describes a correction and an extension in the previously published large signal equivalent circuit model for a circular capacitive micromachined ultrasonic transducer (CMUT) cell The force model is rederived so that the energy and power is preserved in the equivalent circuit model The model is able to predict the entire behavior of CMUT until the membrane touches the substrate Many intrinsic properties of the CMUT cell, such as the collapse condition, collapse voltage, the voltage–displacement interrelation and the force equilibrium before and after collapse voltage in the presence of external static force, are obtained as a direct consequence of the model The small signal equivalent circuit for any bias condition is obtained from the large signal model The model can be implemented in circuit simulation tools and model predictions are in excellent agreement with finite element method simulations

89 citations