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Phased array tuning for optimal ultrasonic guided wave mode selection

AIP Conference Proceedings 2014年第1期1581卷 348-352页

作者： J. H. Bostron J. L. Rose C. A. Moose Pennsylvania State University Grad. Program in Acoustics 201 Applied Science Bldg. University Park PA 16802 USA Pennsylvania State University Department of Eng. Sci. & Mechanics 212 Earth & Eng. Sciences Bldg. University Park PA 16802 USA Applied Research Laboratory P.O. Box 30 State College PA 16804 USA

Ultrasonic guided waves have become widely used in a variety of nondestructive evaluation applications due to their efficiency in defect detection, ability to inspect hidden areas, and other reasons. With a thorough understanding of guided wave mechanics, researchers can predict which guided wave modes will have a high probability of success in a particular nondestructive evaluation application. However, work continues to find optimal mode and frequency selection. An “optimal” mode could give the highest sensitivity to defects or the greatest penetration power, increasing inspection efficiency. In this work, we consider the use of guided interface waves for bond evaluation. A phased comb array transducer is used to sweep in the phase velocity – frequency space in an effort to determine optimal modes.

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Heat transfer enhancement through thermoacoustically-driven streaming

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Proceedings of Meetings on acoustics 2013年第1期19卷

作者： Randall A. Ali Steven L. Garrett Graduate Program in Acoustics Penn State University Applied Research Lab State College PA 16804 Grad. Prog. in Acoustics Penn State University PO Box 30 State College PA 16801-0030

We recently reported on a simple standing-wave thermoacoustic engine that was intended for use as a self-powered monitor of temperature within a resonator that was similar to a nuclear fuel rod [JASA 132 (3) Pt. 2, 1993-1994 (2012)]. An additional potential benefit of such a device is the enhanced heat transfer between the heat source and the surrounding coolant produced by the acoustic streaming generated by the high-amplitude acoustic standing wave within the resonator. By adding a remotely-operated linear actuator that can depresses a valve at the ambient-temperature end of the resonator, we are able to squelch the acoustic resonance by modification of that boundary condition without changing any other operating parameters (e.g., heater power). We will report heat transfer measurements made in a calorimeter at several input thermal power levels with and without the presence of the thermoacoustic oscillations. [Work supported by the U.S. Department of Energy.]

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Acoustic scattering in bubbly water at frequencies below individual bubble resonances

Acoustic scattering in bubbly water at frequencies below ind...

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11th European Conference on Underwater acoustics, ECUA 2012

作者： Culver, Richard L. McElhone, Dale J. Smith, Robert W. Applied Research Lab and Grad Program in Acoustics Pennsylvania State University P.O. Box 30 State College PA 16804 United States

We are interested in acoustic scattering by bubble clouds in water at frequencies and densities such that the acoustic wavelength is large relative to the average distance between bubbles and large relative to that corresponding to the bubble resonance frequency. At high frequency and moderate bubble density, bubble scattered intensity is proportional to N (the number density of the bubbles, m 4), which corresponds to incoherent scattering. Effective medium theory has been shown to predict predominantly incoherent scattering at high frequencies, but coherent scattering (scattered intensity proportional to N2) at lower frequencies. Applying incoherent scattering at low frequencies can substantially under predict the bubble scattered signal. Coherent (low frequency) scattering from bubble assemblages has also been explained in terms of collective shape, but this approach does not provide a means of predicting the temporal extent of the scattered signal in low frequency regimes. The literature apparently does not provide precise guidance as to when and how bubble scattering transitions from incoherent to coherent scattering in response to increasing wavelength, and the relationship between the acoustic wavelength and average bubble separation. Modeling and a tank experiment are underway that we hope will provide some answers to this question. © 2012 Acoustical Society of America.

关键词： Incoherent scattering

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An introduction to the Physical acoustics Technical Committee activities

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The Journal of the Acoustical Society of America 2012年第3_SUPPLEMENT期132卷 1900-1900页

作者： Steven L. Garrett Grad. Prog. in Acoustics Applied Research Lab Penn State University P.O. Box 30 State College PA 16804sxg185@psu.edu

The primary activity of any ASA Technical Committee is to use collective wisdom of the Committee’s membership to determine which research topics within its specialization area are most active and interesting. Based on that assessment, the Committee organizes special sessions at future meetings that will bring together experts from those areas, not necessarily limited to the Society members, who can share interesting results and provide guidance regarding the directions that will lead to further understanding. In Physical acoustics, that is a particularly daunting challenge given the scope of topics that fall within its purview: use of sound to probe material properties, sound propagation and attenuation mechanisms on this planet and in other parts of the universe, and physical effects of sound and its interaction with other forms of radiation, all of which could also go well beyond the limitations of a linear acoustical theory. Needless to say, involvement in debates about “what’s hot” is both interesting and educational. Other activities include proposals for Technical Initiatives that allocate ASA resources. Recently, PATC received funding to sponsor a demonstration session at the Physical acoustics Summer School.

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Comparison of particle filter and histogram filter performance for passive sonar localization

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Proceedings of Meetings on acoustics 2009年第1期8卷

作者： Colin W. Jemmott Richard L. Culver Jack W. Langelaan Grad. Program in Acoustics The Pennsylvania State University P.O. Box 30 State College PA 16804 Applied Research Lab and Grad. Program in Acoustics The Pennsylvania State University P.O. Box 30 State College PA 16804 Aerospace Engineering Penn State State College PA

This paper compares the performance of histogram and particle filters for localizing and tracking a highly maneuvering target using two widely spaced horizontal passive sonar arrays. Both filters are numerical implementations of Bayes' filter, which use recursively estimate state vectors with nonlinear update equations and non-Gaussian prior probability density functions. The histogram filter uses a grid-based approach that is analogous to midpoint rectangular integration, while the particle filter uses a direct Monte Carlo approach. Both filters are shown to successfully track a source in an example with synthetic data given sufficient computational resources. Their performance is also compared in situations where computational power is severely restricted; then the particle filter outperforms the histogram filter in this example.

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Modeling Correlation for Passive Sonar Bayesian Localization Techniques

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Proceedings of Meetings on acoustics 2009年第1期6卷

作者： Colin W. Jemmott Richard L. Culver N. K. Bose Brett E. Bissinger Grad. Program in Acoustics The Pennsylvania State University P.O. Box 30 State College PA 16804 Applied Research Lab and Grad. Program in Acoustics The Pennsylvania State University P.O. Box 30 State College PA 16804 Electrical Engineering The Pennsylvania State University 209C Electrical Engineering West University Park PA 16802 Electrical Engineering The Pennsylvania State University P.O. Box 30 State College PA 16804

Low frequency acoustic signals in shallow water are strongly affected by interference between multiple paths resulting from boundary interactions. As an acoustic source or receiver moves through this interference pattern, the spatial variation in transmission loss can result in strong temporal modulation of the received signal, which can be used to localize the source. Acoustic propagation models can produce accurate transmission loss predictions, but are sensitive to ocean environmental parameters such as bottom composition, bathymetry and sound speed profile. If the uncertainty in the undersea environment can be described by probability density functions of these parameters, Monte Carlo forward models can be used to produce an ensemble of possible transmission loss realizations. A probabilistic model representing this ensemble must include a density function of transmission loss at each location, as well as correlation of transmission loss between locations. In addition, the choice of probabilistic model has a large impact on the form of the resulting Bayesian localization algorithm. Previous results have shown that including spatial correlation of transmission loss can result in improved detection. This paper introduces a non-Gaussian probabilistic model for representing uncertainty in transmission loss predictions that includes correlation.

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On the perception of crackle in noise radiated from military jet aircraft

On the perception of crackle in noise radiated from military...

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12th AIAA/CEAS Aeroacoustics Conference

作者： Gee, Kent L. Sparrow, Victor W. Atchley, Anthony Gabrielson, Thomas B. Brigham Young University Provo UT 84602 Pennsylvania State University University Park PA 16802 Dept. of Physics and Astronomy Brigham Young Univ. N319 ESC Provo UT 84602 Grad. Prog. in Acoustics Penn. State Univ. 316B Leonhard Bldg. University Park PA 16802 Department of Acoustics Grad. Prog. in Acoustics Penn State Univ. 217 Applied Science Bldg. University Park PA 16802 Applied Research Lab. Penn State Univ. P.O. Box 30 State College PA 16804 AIAA

ISBN: (纸本)1563478099

Crackle is a phenomenon sometimes found in supersonic jet noise. It has been commonly quantified by the skewness of the time waveform. In this investigation, a simulated waveform with a virtually identical probability density function and power spectrum as an actual F/A-18E afterburner recording has been created by nonlinearly transforming a statistically Gaussian waveform. Although the afterburner waveform crackles noticeably, playback of the non-Gaussian simulated waveform yields no perception of crackle at all, despite its relatively high skewness. Closer examination of the two waveforms reveals that although they have virtually identical statistics, there are considerable differences in their time rates of change in the intense compressive portions of the waveforms. The afterburner waveform is much more shock-like with its more rapid variations in pressure that the non-Gaussian simulated waveform. This results in a significant difference in the probability distributions of the time derivatives of the actual and simulated data and suggests that the perception of crackle in jet noise waveforms may be better quantified with statistics of the time derivative of the waveform, rather than by the skewness of the time waveform itself.

关键词： Acoustic noise

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Nonlinear modeling of F/A-18E noise propagation

Nonlinear modeling of F/A-18E noise propagation

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Collection of Technical Papers - 11th AIAA/CEAS Aeroacoustics Conference

作者： Gee, Kent L. Sparrow, Victor W. Gabrielson, Thomas B. Atchley, Anthony A. Pennsylvania State University University Park PA 16802 Grad. Prog. in Acoustics Penn State Univ. 202 Applied Science Bldg. University Park PA 16802 AIAA Grad. Prog. in Acoustics Penn State Univ. 316B Leonhard Bldg. University Park PA 16802 Applied Research Lab. Penn State Univ. P.O. Box 30 State College PA 16804 Department of Acoustics Grad. Prog. in Acoustics Penn State Univ. 217 Applied Science Bldg. University Park PA 16802

ISBN: (纸本)1563477300

An algorithm has been developed to study the nonlinear propagation of high-amplitude jet noise. The hybrid time-frequency domain algorithm employs a split-step solution to a Mendousse-Burgers equation that includes the effects of quadratic nonlinearity, atmospheric absorption and dispersion, and geometrical spreading. Spectral predictions generated using the algorithm are compared to recent F/A-18E engine run-up noise measurements made at afterburner and military thrust conditions at distances of 74 and 150 m from the engine nozzles. The agreement between the predicted and measured spectra is such that the results help confirm that energy transfer is occurring to higher frequencies. However, the differences between the model and the measurement raise important issues regarding some of the physical phenomena likely associated with the measurement but not accounted for in the model. Among these are the substantial multipath interference effects in the measured spectra and the finite extent of the aeroacoustic sources within the jet. Copyright © 2005 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Acoustic wave propagation

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Bispectral analysis of high-amplitude jet noise

Bispectral analysis of high-amplitude jet noise

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Collection of Technical Papers - 11th AIAA/CEAS Aeroacoustics Conference

作者： Gee, Kent L. Atchley, Anthony A. Falco, Lauren E. Gabrielson, Thomas B. Sparrow, Victor W. Pennsylvania State University University Park PA 16802 United States Grad. Prog. in Acoustics Penn State Univ. 202 Applied Science Bldg. University Park PA 16802 United States AIAA United States Department of Grad. Prog. in Acoustics Penn State Univ. 217 Applied Science Bldg. University Park PA 16802 United States Applied Research Lab. Penn State Univ. P.O. Box 30 State College PA 16804 United States Grad. Prog. in Acoustics Penn State Univ. 316B Leonhard Bldg. University Park PA 16802 United States

ISBN: (纸本)1563477300

The overall sound pressure levels of noise radiated by military jet aircraft along certain angles are such that nonlinearity is likely to influence the propagation. Bispectral analysis of noise data from the F/A-18E Super Hornet has been carried out in order to provide further evidence that nonlinear effects are indeed present. The bicoherence, which is a normalized form of the bispectral density, has been previously used in a variety of applications to detect quadratic phase coupling (QPC) in a signal. In this case, the results of the bicoherence calculations indicate that QPC is indeed present at high-thrust conditions along the peak radiation angles, which means that nonlinearity does play a role. However, additional investigations are still needed to more fully understand the physical interpretation of the bispectral results for a random noise signal, which will also help better quantify the role of nonlinearity in jet noise propagation. Copyright © 2005 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Acoustic noise

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Preliminary analysis of nonlinearity in F/A-18E/F noise propagation

Preliminary analysis of nonlinearity in F/A-18E/F noise prop...

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Collection of Technical Papers - 10th AIAA/CEAS Aeroacoustics Conference

作者： Gee, Kent L. Gabrielson, Thomas B. Atchley, Anthony A. Sparrow, Victor W. Pennsylvania State University University Park PA 16802 United States Penn State Univ. 202 Applied Science Bldg. University Park PA 16802 United States Applied Research Lab. Penn State Univ. P.O. Box 30 State College PA 16804 United States Grad. Prog. in Acoustics Penn State Univ. 217 Applied Science Bldg. University Park PA 16802 United States Grad. Prog. in Acoustics Penn State Univ. 316B Leonhard Bldg. University Park PA 16802 United States

ISBN: (纸本)1563477130

Analyses of recent F/A-18E/F military power and afterburner measurements suggest that the noise propagation is nonlinear in the far field. Spectral broadening takes place as the radiated noise propagates from IS to 150 m, the limits of the measurement range. This broadening phenomenon cannot be readily explained in terms of linear propagation effects. Calculation of a nonlinearity indicator derived by Howell and Morfey supports the assertion that nonlinear propagation effects are present. Furthermore, skewness and kurtosis calculations indicate that the noise data distributions are non-Gaussian over the propagation range at these engine settings. Finally, the measured spectra have been compared against predictions obtained with existing nonlinear spectral evolution methods. Even though the prediction results compare poorly with the actual measurements, this is attributable to limitations of the spectral evolution methods themselves. Copyright © 2004 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Acoustic noise

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