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American Control Conference

作者： Jesse Pentzer Karl Reichard Sean Brennan Applied Research Lab The Pennsylvania State University University Park 16803 USA Faculty of the Graduate Program in Acoustics The Pennsylvania State University University Park 16803 USA Faculty of the Department of Mechanical Engineering The Pennsylvania State University University Park 16803 USA

ISBN: (纸本)9781467386838

This paper presents a method of path planning for skid-steer robots using an energy-based heuristic. A kinematic model of skid-steer motion utilizing the instantaneous centers of rotation (ICRs) between the tracks and the ground surface is used to predict vehicle motion. A model of skid-steer robot power usage, which also utilizes ICR estimates for slip velocity calculation, is implemented to generate estimates of energy usage. The kinematic and power use models are fused with a Sampling Based Model Predictive Optimization algorithm to plan energy efficient paths through operational areas with mixed surface types. The results of planning paths through both simulated and real-world environments are presented and show that small increases in distance can result in significant energy savings for skid-steer robots.

关键词： Path planning Vehicles Tracking Kinematics Prediction algorithms Robots Predictive models

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An assessment of noise exposure along the High Line, New York City 44

An assessment of noise exposure along the High Line, New Yor...

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44th International Congress and Exposition on Noise Control Engineering, INTER-NOISE 2015

作者： Bourdeau, E.P. Zheng, X.Y.K. King, E.A. Pilla, F. Acoustics Program and Lab College of Engineering Technology and Architecture University of Hartford CT United States Department of Civil Structural and Environmental Engineering Trinity College Dublin Ireland

The High Line is an elevated public park in New York City, transformed from an unused freight rail line. Pedestrians walking through Manhattan's West Side can walk either on the High Line or on a sidewalk below. It is hypothesized that pedestrian exposure to environmental noise on the High Line will be reduced due to the greater segregation of road traffic and pedestrians. In order to test this hypothesis two types of noise measurements were taken: fixed spot measurements and measurements in transit. Fixed noise measurements are standard for environmental noise assessments and offer a reliable representation of the noise level at each measurement location. Measurements in transit provide high spatial resolution and, in this case, may offer a more appropriate representation of the noise a pedestrian is exposed to in the urban environment. Measurements were analyzed to investigate if pedestrians using the High Line would have a lower exposure to those using the sidewalk. Results show statistically significant differences between noise exposure levels. This paper also discusses the potential for using measurements in transit in place of fixed spot measurements for the assessment of environmental noise exposure in urban environments. © 2015 by ASME.

关键词： Pavements

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Heat transfer enhancement through thermoacoustically-driven streaming

Heat transfer enhancement through thermoacoustically-driven ...

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21st International Congress on acoustics, ICA 2013 - 165th Meeting of the Acoustical Society of America

作者： Ali, Randall A. Garrett, Steven L. Graduate Program in Acoustics Penn State University Applied Research Lab. State College PA 16804 United States

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. © 2013 Acoustical Society of America.

关键词： Elastic waves

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A New Cosmic Dust Detector with a Novel Method Using a Resistive Grid Sensitive to Hypervelocity Impacts

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Procedia Engineering 2013年 58卷 68-76页

作者： Mark J. Burchell R. Corsaro F. Giovane M. Cole A. Sadilek M.C. Price J.-C. Liou School of Physical Sciences University of Kent Canterbury Kent CT2 7NH UK Sotera at US Naval Research Lab Physical Acoustics Branch Washington DC 20375 USA Department of Physics Virginia Polytechnic Institute Blacksberg VA 24061 USA United States Naval Academy 590 Holloway Road Annapolis MD 21402 USA NASA Orbital Debris Program Office NASA/JSC Houston Texas 77058 USA

A new method is demonstrated to detect impacts of hypervelocity particles in real-time and to determine the size of particles. It uses a resistive grid on a thin substrate (here Duroid). Penetration of the substrate in an impact breaks lines on the grid, changing the overall resistance of the grid. The change in resistance is proportional to the width of the damaged area (i.e. number of resistive lines that are broken), which is in turn proportional to the impactor size. This method provides a large area, low mass, low power detector for measuring the flux of small dust particles in space. Based on experimental data (taken in a two-stage light gas gun), we show that impacts at 5 km s -1 demonstrate that the principle works as described for particles 150 μm and above and that in theory could work for impacts down to size scales as small as 50 μm.

关键词： Hypervelocity Coopper Dust Grid Impact

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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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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

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Sensors synergistic with nature for in-pile nuclear reactor measurements

Sensors synergistic with nature for in-pile nuclear reactor ...

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2012 Future of Instrumentation International Workshop, FIIW 2012

作者： Smith, James A. Kotter, Dale Garrett, Steven L. Ali, Randall A. Fundamental Fuel Properties Idaho National Lab. Idaho Falls ID United States Graduate Program in Acoustics Penn State University State College PA United States

ISBN: (纸本)9781467324823

To be able to evolve fuel and structural microstructure within a nuclear power reactor in an engineered manner, an effective extreme environment sensor must exist. The development of sensor technology for nondestructive and nonintrusive measurements in harsh environments is a very active field. However most of the effort has been in adapting existing sensing technology to meet the harsh environmental requirements. A different approach is being presented. The fundamental question that we are trying to answer is how do we take advantage of the harsh environment and maintain synergy between the sensor and the environment. This paper will discuss the synergistic sensor being developed that takes advantage of harsh environments. © 2012 IEEE.

关键词： Piles

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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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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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