Linda Franzoni

Journal Article The Journal of the Acoustical Society of America · April 2019 Analytical solutions are presented for broadband sound fields in three rectangular enclosures with absorption applied on the floor and ceiling, rigid sidewalls, and a vertically oriented dipole source. The solutions are intended to serve as benchmarks that ... Full text Cite

Sound attenuation and prediction of porous media properties in hybrid ducts utilizing spatially periodic area changes

Journal Article 2008 Proceedings of the Noisecon ASME Ncad Ncad 2008 · October 16, 2009 A theory based on cross-sectional averaging is developed to analyze quasi-one-dimensional acoustic propagation in hybrid ducts with two propagation media in the cross-section. Specifically, ducts lined with a thick layer of porous material are considered. ... Cite

Noise reduction strategies using multi-element flexible structures

Journal Article 2008 Proceedings of the Noisecon ASME Ncad Ncad 2008 · October 16, 2009 Sound transmission through multi-element flexible barriers is studied. Configurations analyzed include panels with different thickness and elastic modulus in different regions and layered structures connected by an elastic suspension. The purpose of the re ... Cite

Characterization of high frequency radiation from panels subject to broadband excitation

Journal Article 2008 Proceedings of the Noisecon ASME Ncad Ncad 2008 · October 16, 2009 In the high frequency limit, a vibrating panel subject to spatially-random temporally-broadband forcing is shown to have broadband power and directivity properties that can be expressed in simple analytical terms by a limited set of parameters. A lightly-l ... Cite

Prediction and modification of broadband interior noise in enclosures using energy-intensity bem and absorption scaling

Journal Article 2008 Proceedings of the Noisecon ASME Ncad Ncad 2008 · October 16, 2009 Enclosures with difliise reflection boundaries are modeled with an energy-intensity boundary element method using uncorrelated broadband directional sources. Input power is assumed to enter the enclosure through the walls, which are also absorptive. An abs ... Cite

Characterization of high frequency radiation from panels subject to broadband excitation

Journal Article American Society of Mechanical Engineers Noise Control and Acoustics Division Publication Ncad · December 1, 2008 In the high frequency limit, a vibrating panel subject to spatially-random temporally-broadband forcing is shown to have broadband power and directivity properties that can be expressed in simple analytical terms by a limited set of parameters. A lightly-l ... Full text Cite

Noise reduction strategies using multi-element flexible structures

Journal Article American Society of Mechanical Engineers Noise Control and Acoustics Division Publication Ncad · December 1, 2008 Sound transmission through multi-element flexible barriers is studied. Configurations analyzed include panels with different thickness and elastic modulus in different regions and layered structures connected by an elastic suspension. The purpose of the re ... Full text Cite

Prediction and modification of broadband interior noise in enclosures using energy-intensity bem and absorption scaling

Journal Article American Society of Mechanical Engineers Noise Control and Acoustics Division Publication Ncad · December 1, 2008 Enclosures with diffuse reflection boundaries are modeled with an energy-intensity boundary element method using uncorrelated broadband directional sources. Input power is assumed to enter the enclosure through the walls, which are also absorptive. An abso ... Full text Cite

Sound attenuation and prediction of porous media properties in hybrid ducts utilizing spatially periodic area changes

Journal Article American Society of Mechanical Engineers Noise Control and Acoustics Division Publication Ncad · December 1, 2008 A theory based on cross-sectional averaging is developed to analyze quasi-one-dimensional acoustic propagation in hybrid ducts with two propagation media in the cross-section. Specifically, ducts lined with a thick layer of porous material are considered. ... Full text Cite

A perfect storm: Examining natural disasters by combining traditional teaching methods with service-learning and innovative technology

Journal Article International Journal of Engineering Education · July 28, 2008 In spring 2006, Duke University piloted a new, interdisciplinary, service-learning course, in which undergraduate, graduate, and professional students conducted a life cycle analysis of natural disasters. Invited experts discussed: the range of meteorologi ... Cite

Transcending the traditional: Using tablet PCs to enhance engineering and computer science instruction

Conference Proceedings Frontiers in Education Conference Fie · December 1, 2007 Traditional instructional methods present many obstacles to effective teaching and learning in engineering and computer science courses. These include a reliance on text-based or static mediums to convey equation- and graphics-heavy concepts, a disconnect ... Full text Cite

Prediction of broadband sound fields in enclosures by decomposition in powers of an absorption parameter

Journal Article 12th International Congress on Sound and Vibration 2005 Icsv 2005 · December 1, 2005 A novel analysis for steady-state or time-dependent broadband diffuse sound fields in enclosures is developed. Beginning with a formulation utilizing broadband intensity boundary sources, the strength of these wall sources is expanded in a series in powers ... Cite

Improvement of a high-frequency broadband energy-intensity boundary element method to include high resolution specular reflection

Journal Article Journal of Computational Acoustics · March 1, 2005 The prediction of the spatial mean-square pressure distribution within enclosed high-frequency broadband sound fields is computationally intensive if determined on a frequency-by-frequency basis. Recently an energy-intensity boundary element method (EIBEM) ... Full text Cite

Analytical-numerical matching for fluid-loaded structures with discontinuities

Journal Article Journal of the Acoustical Society of America · November 1, 2004 The method of analytical-numerical matching (ANM) is applied to several example problems involving the radiation and vibration of a fluid-loaded cylindrical shell with structural discontinuities. These problems are used to verify the accuracy of the method ... Full text Cite

Assessment of the contribution of panel vibration to airframe noise

Journal Article AIAA Journal · January 1, 2004 Aerodynamic noise sources not associated with propulsion are termed "airframe noise." As well-known sources such as flow separation, landing gear vortex shedding, and flap-edge noise are further reduced, the noise sources from the clean airframe will need ... Full text Cite

Efficient calculation of vibration and radiation from fluid-loaded structures with discontinuities using analytical-numerical matching

Journal Article Proceedings of the Tenth International Congress on Sound and Vibration · December 1, 2003 Solving structural acoustic problems in the mid-frequency range is a challenging task. Computation is expensive due to the large well-coupled nature of the fluid-structure system. Discrete structural elements cause localized discontinuities that require mu ... Cite

An angle-by-angle approach to predicting broadband high-frequency sound fields in rectangular enclosures with experimental comparison

Journal Article Journal of the Acoustical Society of America · October 1, 2003 Experiments were performed on an elongated rectangular acoustic enclosure with different levels of absorptive material placed on side walls and an end wall. The acoustic source was a broadband high-frequency sound from a loudspeaker flush-mounted to an end ... Full text Cite

A power conservation approach to predict the spatial variation of the cross-sectionally averaged mean-square pressure in reverberant enclosures

Journal Article Journal of the Acoustical Society of America · December 29, 2001 Although it is commonly assumed that broadband mean-square pressure levels are spatially uniform in reverberant enclosures, there is a gradual spatial variation, especially if the room is long in one direction, and/or the acoustic absorption is not applied ... Full text Cite

An acoustic boundary element method based on energy and intensity variables for prediction of high-frequency broadband sound fields

Journal Article Journal of the Acoustical Society of America · December 29, 2001 A boundary element method is formulated in terms of time-averaged energy and intensity variables. The approach is applicable to high modal density fields but is not restricted to the usual low-absorption, diffuse, and quasiuniform assumptions. A broadband ... Full text Cite

An estimate of airframe noise caused by structural vibration

Journal Article 6th Aeroacoustics Conference and Exhibit · December 1, 2000 Airframe noise due to structural vibration is estimated. This estimate shows that panel vibration driven by turbulent boundary layer fluctuations can produce airframe noise levels comparable to those measured on aerodynamically "clean" airframe configurati ... Cite

Energy based boundary element method for broadband high frequency sound fields

Journal Article 6th Aeroacoustics Conference and Exhibit · December 1, 2000 An acoustic boundary element method is formulated using the time-averaged intensity and mean-square pressure. A continuous distribution of uncorrelated broadband high frequency sources is used to represent the boundaries of the enclosure. Local correlation ... Cite

Using analytical/numerical matching with finite element analysis to solve a fluid-loaded structural dynamics problem

Journal Article American Society of Mechanical Engineers Dynamic Systems and Control Division Publication DSC · December 1, 2000 Two model problems are solved using a combination of Analytical/Numerical Matching (ANM) and Finite Element Analysis (FEA). The first problem is that of a thick, finite length beam driven by the motion of a small rigid support attached to its lower boundar ... Cite

An estimate of airframe noise caused by structural vibration

Conference 6th Aeroacoustics Conference and Exhibit · January 1, 2000 Airframe noise due to structural vibration is estimated. This estimate shows that panel vibration driven by turbulent boundary layer fluctuations can produce airframe noise levels comparable to those measured on aerodynamically "clean" airframe configurati ... Full text Cite

Energy based boundary element method for broadband high frequency sound fields

Conference 6th Aeroacoustics Conference and Exhibit · January 1, 2000 An acoustic boundary element method is formulated using the time-averaged intensity and mean-square pressure. A continuous distribution of uncorrelated broadband high frequency sources is used to represent the boundaries of the enclosure. Local correlation ... Full text Cite

Using analytical/numerical matching with finite element analysis to solve a fluid-loaded structural dynamics problem

Conference ASME International Mechanical Engineering Congress and Exposition Proceedings Imece · January 1, 2000 Two model problems are solved using a combination of Analytical/Numerical Matching (ANM) and Finite Element Analysis (FEA). The first problem is that of a thick, finite length beam driven by the motion of a small rigid support attached to its lower boundar ... Full text Cite

An illustration of analytical/numerical matching with finite-element analysis for structural vibration problems

Journal Article Journal of the Acoustical Society of America · January 1, 2000 Analytical/numerical matching (ANM) is an accurate and efficient method for solving many types of problems with discontinuities. The method separates local and global effects, and solves separate subproblems using high resolution around the discontinuity a ... Full text Cite

A study of damping effects on spatial distribution and level of reverberant sound in a rectangular acoustic cavity

Journal Article Journal of the Acoustical Society of America · August 20, 1999 Based on computer simulations of sound fields in rectangular enclosures, important observations are made regarding sound pressure levels and the spatial variation of the broadband reverberant field. From these observations an empirical formula is deduced t ... Full text Cite

An innovative design of a probe-tube attachment for a 1/2 -in. microphone

Journal Article Journal of the Acoustical Society of America · November 1, 1998 Nonintrusive devices are needed to measure sound pressure levels in the mid- to high-frequency range. This need arises due to the small acoustic wavelengths which are present at these frequencies, and the interference caused by conventional microphones whi ... Full text Cite

A discussion of modal uncoupling and an approximate closed-form solution for weakly coupled systems with application to acoustics

Journal Article Journal of the Acoustical Society of America · April 1, 1998 Modal analysis is often used to solve problems in acoustics, leading to a system of coupled equations for the modal amplitudes. A common practice in analytical work utilizing modal analysis has been to assume that weak modal coupling is negligible, thereby ... Full text Cite

On the accuracy of modal analysis in reverberant acoustical systems with damping

Journal Article Journal of the Acoustical Society of America · January 1, 1995 That the modal analysis method works well regardless of the amount of damping in the system, provided that modal coupling is included in the analysis, is shown. The soundfield produced by a vibrating piston in a tube with an absorptive end is calculated. A ... Full text Cite