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Bond integrity of a plate wave guide on a half space

AIP Conference Proceedings 2012年第1期1430卷 1323-1330页

作者： J. H. Bostron J. L. Rose C. A. Moose Graduate Program in Acoustics The Pennsylvania State University University Park PA 16802 USA Department of Engineering Science and Mechanics The Pennsylvania State University University Park PA 16802 USA Composite Materials Division Applied Research Laboratory The Pennsylvania State University University Park PA 16804 USA

Bond integrity is of interest to researchers in non-destructive evaluation because it is used as an indicator when assessing the health of structures. In this study, a plate waveguide on a half space is examined to find features associated with bond integrity. Analytical and finite element models are developed to describe wave propagation. Mode and frequency selection optimization is discussed. Preliminary results suggest that changes in arrival time and amplitude can be used to detect the length of a very weak bond when using a special mode of strong in-plane displacement at the interface.

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Acoustic cavitation localization in reverberant environments

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The Journal of the Acoustical Society of America 2012年第3_SUPPLEMENT期132卷 2055-2055页

作者： Samuel J. Anderson Daniel A. Perlitz William K. Bonness Dean E. Capone The Graduate Program in Acoustics The Pennsylvania State University State College PA 16801sja183@psu.edu Engineering Sciences The Pennsylvania State University State College PA Noise Control and Hydroacoustics Applied Research Laboratory - PSU State College PA

Cavitation detection and localization techniques generally require visual access to the fluid field, multiple high-speed cameras, and appropriate illumination to locate cavitation. This can be costly and is not always suitable for all test environments, particularly when the bubble diameter is small or duration is short. Acoustic detection and localization of cavitation can be more robust and more easily implemented, without requiring visual access to the site in question. This research utilizes the distinct acoustic signature of cavitation events to both detect and localize cavitation during experimental water tunnel testing. Using 22 hydrophones and the processing techniques plane-wave beamforming and Matched-Field Processing (MFP), cavitation is accurately and quickly localized during testing in a 12” diameter water tunnel. Cavitation is induced using a Nd:YAG laser for precise control of bubble location and repeatability. Accounting for and overcoming the effects of reflections on acoustic localization in acoustically small environments is paramount in water tunnels, and the techniques employed to minimize error will be discussed.

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Simple Herriott-type high energy femtosecond laser with two notched mirrors

Simple Herriott-type high energy femtosecond laser with two ...

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2011 International Quantum Electronics Conference, IQEC 2011 and Conference on Lasers and Electro-Optics, CLEO Pacific Rim 2011

作者： Song, Dong Hoon Cha, Yong Ho Kim, Kyung Nam Hwang, Sung In Jeong, Young Uk Ko, Do-Kyeong Graduate Program of Photonics and Applied Physics Gwangju Institute of Science and Technology Gwangju 500-712 Korea Republic of Advanced Photonics Research Institute Gwangju Institute of Science and Technology Gwangju 500-712 Korea Republic of Lab. for Quantum Optics Korea Atomic Energy Research Institute P. O. Box 105 Yusong Daejeon 305-605 Korea Republic of

ISBN: (纸本)9780977565771

关键词： Femtosecond lasers

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An information theoretic performance bound for passive sonar localization of a moving source 44th

An information theoretic performance bound for passive sonar...

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44th Annual Conference on Information Sciences and Systems, CISS 2010

作者： Jemmott, Colin W. Culver, R. Lee Bissinger, B.E. Gaumond, Charles F. Graduate Program in Acoustics Pennsylvania State University State College PA 16801 United States Applied Research Laboratory Pennsylvania State University State College PA 16801 United States Electrical Engineering Department Pennsylvania State University State College PA 16801 United States Acoustics Division Naval Research Laboratory Washington DC 20375 United States

ISBN: (纸本)9781424474172

Several passive sonar signal processing methods have previously been developed for determining the location of a source radiating tonal acoustic energy while moving through a shallow water environment. These localization algorithms rely on the complex interference pattern resulting from multipath acoustic propagation. By treating passive sonar localization as a communications problem, an information theoretic upper bound on performance can be derived. The bound is based on acoustic propagation, and depends on radial distance the source travels through the waveguide, signal to noise ratio, frequency of the radiated acoustic tone, and minimum sound speed of the problem, and resolution of the localization. An example using parameters from the SWellEx-96 experiment is shown. ©2010 IEEE.

关键词： Signal to noise ratio

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An audio reproduction grand challenge: Design a system to sonic boom an entire house

An audio reproduction grand challenge: Design a system to so...

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125th Audio Engineering Society Convention 2008

作者： Sparrow, Victor W. Garrett, Steven L. Graduate Program in Acoustics Pennsylvania State University 201 Applied Science Bldg. University Park PA 16802 United States Graduate Program in Acoustics Applied Research Laboratory Pennsylvania State University University Park PA 16802 United States

ISBN: (纸本)9781605607122

This paper describes an ongoing research study to design a simulation device that can accurately reproduce sonic booms over the outside surface of an entire house. Sonic booms and previous attempts to reproduce them will be reviewed. The authors will present some calculations which suggest that it will be very difficult to produce the required pressure amplitudes using conventional sound reinforcement electroacoustic technologies. However, an additional purpose is to make AES members aware of this research and to solicit feedback from attendees prior to a January 2009 down-selection activity for the design of an outdoor sonic boom simulation system.

关键词： Shock waves

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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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Initial results from the variable intensity sonic boom propagation database

Initial results from the variable intensity sonic boom propa...

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作者： Haering Jr., Edward A. Cliatt II, Larry J. Bunce, Thomas J. Gabrielson, Thomas B. Sparrow, Victor W. Locey, Lance L. NASA Dryden Flight Research Center Edwards CA 93523-0273 United States Pennsylvania State University University Park PA 16802 United States Research Aerodynamics Mail Stop D-2228 United States Applied Research Lab 218 Applied Science Building United States Graduate Program in Acoustics 201 Applied Science Building United States

ISBN: (纸本)9781563479397

An extensive sonic boom propagation database with low-to normal-intensity booms (overpressures of 0.08 lbf/ft2 to 2.20 lbf/ft2) was collected for propagation code validation, and initial results and flight research techniques are presented. Several arrays of microphones were used, including a 10 m tall tower to measure shock wave directionality and the effect of height above ground on acoustic level. A sailplane was employed to measure sonic booms above and within the atmospheric turbulent boundary layer, and the sailplane was positioned to intercept the shock waves between the supersonic airplane and the ground sensors. Sailplane and ground-level sonic boom recordings were used to generate atmospheric turbulence filter functions showing excellent agreement with ground measurements. The sonic boom prediction software PCBoom4 was employed as a preflight planning tool using preflight weather data. The measured data of shock wave directionality, arrival time, and overpressure gave excellent agreement with the PCBoom4-calculated results using the measured aircraft and atmospheric data as inputs. C-weighted acoustic levels generally decreased with increasing height above the ground. A-weighted and perceived levels usually were at a minimum for a height where the elevated-microphone pressure-rise time history was the straightest, which is a result of incident and groundreflected shock waves interacting.

关键词： Shock waves

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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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An Anisotropic Diffusion Filtering Implementation to Execute in Parallel Distributed Systems

An Anisotropic Diffusion Filtering Implementation to Execute...

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IEEE International Conference on Computational Science and Engineering Workshops (CSEWORKSHOPS)

作者： Antonio C. Sobieranski Leandro Coser M.A.R. Dantas Aldo v. Wangenheim Eros Comunello LAPIX-Image Processing and Graphic Computing Lab The Cyclops Group Federal University of Santa Catarina Brazil LaPeSD-Distributed Systems Research Laboratory Federal University of Santa Catarina Brazil Graduate Program Applied Computer Science Universidade do Vale do Itajaí Brazil

ISBN: (纸本)9780769532578

In this paper, we present a parallelization of a filtering algorithm related to non-linear anisotropic diffusion, used to enhance the performance of an application in a parallel distributed system. The anisotropic diffusion is a well-established technique for image enhancement by means of diffusivity functions, which act as border attenuators. However, it requires a high computational cost when a large amount of data is used. The proposed implementation was parallelized considering both point-to-point and collective communications, adopting the MPI paradigm. Results from both approaches indicate that the proposed algorithm has reached interesting levels of performance (81% and 93% of efficiency, respectively) when compared to the execution of one process in a single computer node. In addition, our results indicate an enhancement of around 21% utilizing the collective communication strategy when compared to point-to-point communication.

关键词： Filtering Magnetic separation Anisotropic magnetoresistance Ions Kernel Maximum likelihood detection Pixel

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Prediction of diesel engine cooling fan noise

Prediction of diesel engine cooling fan noise

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22nd National Conference on Noise Control Engineering, NOISE-CON 2007

作者： Kim, Geon-Seok Lauchle, Gerald C. Brungart, Timothy A. Graduate Program in Acoustics Pennsylvania State University University Park PA 16802 United States Applied Research Laboratory Pennsylvania State University State College PA 16804 United States

ISBN: (纸本)9781604238525

This effort focuses on measuring and predicting the discrete-frequency and broadband noise radiated by a diesel engine cooling fan. In such engine cooling systems, where space is very limited, it would be very difficult if not impossible to measure the fan inflow velocity field using the conventional, stationary hot-wire method. Instead, the fan inflow was measured with a twocomponent x-type hot-film probe attached very close to the leading edge of a rotating blade. The fan's radiated noise was measured without contamination from the engine noise by driving the fan with an electric motor. The spatially non-uniform mean velocity field was used in axial-flow fan noise theory to predict the discrete-frequency noise at the blade-pass frequency and harmonics. The influences due to an upstream finger guard were also investigated. The spacetime correlations of the inflow velocity fluctuations were utilized in stochastic lifting surface theory to calculate the unsteady blade lift and resulting broadband fan noise. The radiated sound power spectra that were measured for the fan are shown to be in excellent agreement with those predicted.

关键词： Stochastic systems

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