scholarly journals Compendium of HFIR and REDC Infrasound and Low-Frequency Acoustic Emissions

2018 ◽  
Author(s):  
David L. Chichester ◽  
Edna S. Cardenas ◽  
Scott M. Watson ◽  
Thomas V. Holschuh ◽  
James T. Johnson ◽  
...  
Keyword(s):  
Acoustic Emissions ◽  
Low Frequency

Low‐frequency acoustic emissions of a plunging water jet. Part II. Theory

1998 ◽  
Vol 104 (3) ◽  
pp. 1749-1749
Author(s):  
Thomas R. Hahn ◽  
Thomas K. Berger ◽  
Michael J. Buckingham
Keyword(s):  
Acoustic Emissions ◽  
Low Frequency ◽  
Water Jet ◽  
Plunging Water Jet

Low‐frequency acoustic emissions of a plunging water jet. Part I. Experiment

1998 ◽  
Vol 104 (3) ◽  
pp. 1749-1749
Author(s):  
Thomas K. Berger ◽  
Thomas R. Hahn ◽  
Michael J. Buckingham
Keyword(s):  
Acoustic Emissions ◽  
Low Frequency ◽  
Water Jet ◽  
Plunging Water Jet

scholarly journals Compendium of HFIR and REDC Infrasound and Low-Frequency Acoustic Emissions

2018 ◽  
Author(s):  
David L. Chichester ◽  
Edna S. Cardenas ◽  
Scott M. Watson ◽  
Thomas V. Holschuh ◽  
James T. Johnson ◽  
...  
Keyword(s):  
Acoustic Emissions ◽  
Low Frequency

Fluidised bed dynamics diagnosis from measurements of low-frequency out-bed passive acoustic emissions

2006 ◽  
Vol 162 (2) ◽  
pp. 145-156 ◽  
Author(s):  
Javier Villa Briongos ◽  
José M. Aragón ◽  
María C. Palancar
Keyword(s):  
Acoustic Emissions ◽  
Low Frequency ◽  
Fluidised Bed ◽  
Passive Acoustic

Objective Low-Frequency Audiometry by Distortion-Product Acoustic Emissions

1991 ◽  
Vol 117 (10) ◽  
pp. 1167-1171 ◽  
Author(s):  
P. Bonfils ◽  
P. Avan ◽  
A. Londero ◽  
J. Trotoux ◽  
P. Narcy
Keyword(s):  
Acoustic Emissions ◽  
Low Frequency ◽  
Distortion Product

Acoustic Detection of Imminent Blowout in Pilot and Swirl Stabilized Combustors

2003 ◽  
Author(s):  
Suraj Nair ◽  
Tim Lieuwen
Keyword(s):  
High Speed ◽  
Strong Dependence ◽  
Acoustic Emissions ◽  
Low Frequency ◽  
Flame Stabilization ◽  
Acoustic Signature ◽  
Wavelet Techniques ◽  
Unsteady Flame ◽  
Intensified Camera ◽  
Experimental Effort

This paper describes an experimental effort to characterize the acoustic emissions of lean, premixed combustors operating near blowout conditions. Its objective is to use measurements of the flame’s acoustic signature to determine the proximity of the combustor to incipient blowout. The feasibility of the method was performed on two combustors with fundamentally different flame holding methods: externally anchored pilot and swirl-stabilized. Acoustic measurements indicate that the low frequency spectrum exhibits a strong dependence upon the degree of flame stabilization. High speed intensified camera images of the flame were also taken to get a better understanding of the unsteady flame dynamics. In the piloted burner, it became visibly obvious that the flame was approaching blowoff by increased flickering, unsteadiness, and non-symmetric flame attachment. The results from the swirl burner, however, show that the blow-off transient was characterized by short duration, localized extinction and re-ignition events. These events increase in frequency and duration as blowout is approached. Several data analysis approaches using spectral, statistical and wavelet techniques with varying degrees of sensitivity are shown to be capable of detecting precursors to blowout for both burners.

scholarly journals A Glove-Based Form Factor for Collecting Joint Acoustic Emissions: Design and Validation

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2683 ◽  
Author(s):  
Nicholas B. Bolus ◽  
Hyeon Ki Jeong ◽  
Daniel C. Whittingslow ◽  
Omer T. Inan
Keyword(s):  
Form Factor ◽  
Knee Joint ◽  
Acoustic Emissions ◽  
Low Frequency ◽  
Suitable Alternative ◽  
Vibrational Signals ◽  
Joint Health ◽  
Instrumented Glove ◽  
Healthy Knee ◽  
Rms Amplitude

Sounds produced by the articulation of joints have been shown to contain information characteristic of underlying joint health, morphology, and loading. In this work, we explore the use of a novel form factor for non-invasively acquiring acoustic/vibrational signals from the knee joint: an instrumented glove with a fingertip-mounted accelerometer. We validated the glove-based approach by comparing it to conventional mounting techniques (tape and foam microphone pads) in an experimental framework previously shown to reliably alter healthy knee joint sounds (vertical leg press). Measurements from healthy subjects (N = 11) in this proof-of-concept study demonstrated a highly consistent, monotonic, and significant (p < 0.01) increase in low-frequency signal root-mean-squared (RMS) amplitude—a straightforward metric relating to joint grinding loudness—with increasing vertical load across all three techniques. This finding suggests that a glove-based approach is a suitable alternative for collecting joint sounds that eliminates the need for consumables like tape and the interface noise associated with them.

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