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40 results on '"Breton, Daniel J."'

1. Interference of the direct and ground-reflected waves in the atmosphere with volumetric scatteringa).

Author

Ostashev, Vladimir E., Breton, Daniel J., and Wilson, D. Keith

Abstract

The interference of the direct and ground-reflected sound waves is significantly affected by volumetric scattering in the atmosphere, such as scattering by turbulence and forest. In the present article, the existing theory describing this interference is generalized to three somewhat independent but equally important cases. First, the attenuation of the direct and ground-reflected waves caused by backscattering is addressed. Second, the existing theory is extended for statistically quasi-homogeneous turbulence in which the variances and length scales of the temperature and wind velocity fluctuations depend on the height above the ground. Third, the existing theory, which was previously formulated only for near-horizontal sound propagation, is generalized to slanted sound propagation as pertinent to elevated sound sources. Numerical results for slanted propagation demonstrate that atmospheric turbulence can significantly increase the sound pressure level at the interference minima. The extended theory of the interference of the direct and ground-reflected waves in the atmosphere with volumetric scattering is important for practical applications, such as auralization of flying aircraft and sound propagation in a forest, and can be adapted to radio wave propagation. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Spatial Structure of the Radio‐Frequency Noise Field in a Large City.

Author

Meyer, Aaron C., Breton, Daniel J., Kamrath, Matthew J., and Vecherin, Sergey N.

Subjects
RADIO frequency, URBAN land use, CITIES & towns, RANDOM fields, NOISE, URBAN morphology, STATISTICAL correlation
Abstract

The urban radio‐frequency (RF) noise generated by our cities continues to change with time. Although models exist to describe the RF noise as functions of frequency and urban land use types, very few models describe the spatial character or structure of the noise on the scales of city blocks (50–150 m). The goal of this work is to investigate the connection between urban morphology and the higher‐order spatial statistics of the noise field. To achieve this goal, a large measurement campaign was conducted in Boston, Massachusetts. Many spatial measurements allowed for calculation of spatial correlation functions of noise power in three different neighborhoods, which were used to quantify the spatial structure of the fields. A statistical point source model is then developed, with adjustable parameters relating to urban morphology. Good agreement between the model and the experimental correlation functions suggests the 25 MHz urban noise field is well described by a random network of fixed point sources, radiating with a 1/r power law behavior. Plain Language Summary: Our modern cities are filled with electronic devices. Each device can emit radiation and contribute to what is called the urban radio‐frequency noise field. The noise field is the combined effect from all these devices. If the noise field is strong enough it can negatively impact wireless communication, and the use of other electric devices. It is important to better understand the nature of the noise field in order to mitigate and plan for its negative effects. This paper describes in detail how the noise field is distributed in space, or its spatial structure. A theoretical model or tool is developed to help predict how the noise field looks spatially. Key Points: Radio‐frequency noise spatial correlation functions were calculated for three different neighborhoods in Boston, MassachusettsGood theoretical agreement suggests the noise field is well described by a random network of point sources radiating with a 1/r behavior [ABSTRACT FROM AUTHOR]

Published
2024
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3. Observing and modeling the influence of layering on bubble trapping in polar firn

Author

Mitchell, Logan E, Buizert, Christo, Brook, Edward J, Breton, Daniel J, Fegyveresi, John, Baggenstos, Daniel, Orsi, Anais, Severinghaus, Jeffrey, Alley, Richard B, Albert, Mary, Rhodes, Rachael H, McConnell, Joseph R, Sigl, Michael, Maselli, Olivia, Gregory, Stephanie, and Ahn, Jinho

Subjects
Climate Action, firn, layering, ice core, methane, firn density, total air content, Atmospheric Sciences, Physical Geography and Environmental Geoscience
Abstract

Interpretation of ice core trace gas records depends on an accurate understanding of the processes that smooth the atmospheric signal in the firn. Much work has been done to understand the processes affecting air transport in the open pores of the firn, but a paucity of data from air trapped in bubbles in the firn-ice transition region has limited the ability to constrain the effect of bubble closure processes. Here we present high-resolution measurements of firn density, methane concentrations, nitrogen isotopes, and total air content that show layering in the firn-ice transition region at the West Antarctic Ice Sheet (WAIS) Divide ice core site. Using the notion that bubble trapping is a stochastic process, we derive a new parameterization for closed porosity that incorporates the effects of layering in a steady state firn modeling approach. We include the process of bubble trapping into an open-porosity firn air transport model and obtain a good fit to the firn core data. We find that layering broadens the depth range over which bubbles are trapped, widens the modeled gas age distribution of air in closed bubbles, reduces the mean gas age of air in closed bubbles, and introduces stratigraphic irregularities in the gas age scale that have a peak-to-peak variability of ~10 years at WAIS Divide. For a more complete understanding of gas occlusion and its impact on ice core records, we suggest that this experiment be repeated at sites climatically different from WAIS Divide, for example, on the East Antarctic plateau.

Published
2015

21. Impact of parametric uncertainties on scattered signal distributions and receiver operating characteristics

Author

Wilson, D. Keith; Breton, Daniel J.; Hart, Carl R.; Ostashev, Vladimir E.; Nykaza, Edward T.; Pettit, Chris L., United States. Army. Corps of Engineers; Engineer Research and Development Center (U.S.); Cold Regions Research and Engineering Laboratory (U.S.); Construction Engineering Research Laboratory (U.S.), Wilson, D. Keith; Breton, Daniel J.; Hart, Carl R.; Ostashev, Vladimir E.; Nykaza, Edward T.; Pettit, Chris L., and United States. Army. Corps of Engineers; Engineer Research and Development Center (U.S.); Cold Regions Research and Engineering Laboratory (U.S.); Construction Engineering Research Laboratory (U.S.)

Abstract

ERDC TR-18-7 Environmental Quality/Installations and Geospatial Research and Engineering Impact of Parametric Uncertainties on Scattered Signal Distributions and Receiver Operating Characteristics Engineer Research and Development Center D. Keith Wilson, Daniel J. Breton, Carl R. Hart, Chris L. Pettit, Edward T. Nykaza, and Vladimir E. Ostashev July 2018 Approved for public release; distribution is unlimited. The U.S. Army Engineer Research and Development Center (ERDC) solves the nation’s toughest engineering and environmental challenges. ERDC develops innovative solutions in civil and military engineering, geospatial sciences, water resources, and environmental sciences for the Army, the Department of Defense, civilian agencies, and our nation’s public good. Find out more at www.erdc.usace.army.mil. To search for other technical reports published by ERDC, visit the ERDC online library at http://acwc.sdp.sirsi.net/client/default. Environmental Quality/Installations and Geospatial Research and Engineering ERDC TR-18-7 July 2018 Impact of Parametric Uncertainties on Scattered Signal Distributions and Receiver Operating Characteristics D. Keith Wilson, Daniel J. Breton, Carl R. Hart, and Vladimir E. Ostashev U.S. Army Engineer Research and Development Center (ERDC) Cold Regions Research and Engineering Laboratory (CRREL) 72 Lyme Road Hanover, NH 03755-1290 Edward T. Nykaza U.S. Army Engineer Research and Development Center (ERDC) Construction Engineering Research Laboratory (CERL) 2902 Newmark Dr. Champaign, IL 61826-9005 Chris L. Pettit U.S. Naval Academy Aerospace Engineering Department 590 Holloway Rd. Annapolis, MD 21402-5042 Final Report Approved for public release; distribution is unlimited. Prepared for Headquarters, U.S. Army Corps of Engineers Washington, DC 20314-1000 Under Environmental Quality/Installations (EQ/I), program element / project / task number 62272089604, “Real-Time Adaptation, Prediction, and Informatics for Dynamic Military Noise Environments

Published
2018

22. Measuring the non-line-of-sight ultra-high-frequency channel in mountainous terrain: A spread-spectrum, portable channel sounder

Author

Streeter, Samuel S.; Breton, Daniel J.; Corgan, Johnathan M., United States. Army. Corps of Engineers; Engineer Research and Development Center (U.S.); Cold Regions Research and Engineering Laboratory (U.S.), Streeter, Samuel S.; Breton, Daniel J.; Corgan, Johnathan M., and United States. Army. Corps of Engineers; Engineer Research and Development Center (U.S.); Cold Regions Research and Engineering Laboratory (U.S.)

Abstract

ERDC/CRREL TR-18-3 ERDC 6.1 Basic Research Measuring the Non-Line-of-Sight Ultra-High-Frequency Channel in Mountainous Terrain A Spread-Spectrum, Portable Channel Sounder Cold Regions Research and Engineering Laboratory Samuel S. Streeter, Daniel J. Breton, and Johnathan M. Corgan March 2018 Approved for public release; distribution is unlimited. The U.S. Army Engineer Research and Development Center (ERDC) solves the nation’s toughest engineering and environmental challenges. ERDC develops innovative solutions in civil and military engineering, geospatial sciences, water resources, and environmental sciences for the Army, the Department of Defense, civilian agencies, and our nation’s public good. Find out more at www.erdc.usace.army.mil. To search for other technical reports published by ERDC, visit the ERDC online library at http://acwc.sdp.sirsi.net/client/default. ERDC 6.1 Basic Research ERDC/CRREL TR-18-3 March 2018 Measuring the Non-Line-of-Sight Ultra-High-Frequency Channel in Mountainous Terrain A Spread-Spectrum, Portable Channel Sounder Samuel S. Streeter and Daniel J. Breton U.S. Army Engineer Research and Development Center (ERDC) Cold Regions Research and Engineering Laboratory (CRREL) 72 Lyme Road Hanover, NH 03755 Johnathan M. Corgan Corgan Labs 6081 Meridian Avenue San Jose, CA 95120 Final Report Approved for public release; distribution is unlimited. Prepared for U.S. Army Corps of Engineers Washington, DC 20314-1000 Under ERDC 6.1 Basic Research Project 462178, “Wide-Band Radio Frequency Propagation” ERDC/CRREL TR-18-3 ii Abstract Very few measurements campaigns have conducted ground-based, radio-frequency propagation field measurement campaigns conducted in deep mountainous terrain, and none have focused on the non-line-of-sight channel in mountain shadow zones. Here, we introduce a versatile, spread-spectrum, portable channel sounder specifically designed to meas-ure the non-line-of-sight, ultra-high-frequency channel in mountainous terrain. The

Published
2018

27. High-fidelity simulations of electromagnetic propagation and RF communication systems: T53 final report

Author

Streeter, Samuel S.; Breton, Daniel J.; Maxson, Michele L.; Goodin, Christopher T., United States. Army. Corps of Engineers; Engineer Research and Development Center (U.S.); Cold Regions Research and Engineering Laboratory (U.S.); Geotechnical and Structures Laboratory (U.S.); Military Engineering Applied Research Program (U.S.), Streeter, Samuel S.; Breton, Daniel J.; Maxson, Michele L.; Goodin, Christopher T., and United States. Army. Corps of Engineers; Engineer Research and Development Center (U.S.); Cold Regions Research and Engineering Laboratory (U.S.); Geotechnical and Structures Laboratory (U.S.); Military Engineering Applied Research Program (U.S.)

Abstract

ERDC TR-17-2 Military Engineering Applied Research High-Fidelity Simulations of Electromagnetic Propagation and RF Communication Systems T53 Final Report Engineer Research and Development Center Samuel S. Streeter, Daniel J. Breton, Michele L. Maxson, and Christopher T. Goodin May 2017 Approved for public release; distribution is unlimited. The U.S. Army Engineer Research and Development Center (ERDC) solves the nation’s toughest engineering and environmental challenges. ERDC develops innovative solutions in civil and military engineering, geospatial sciences, water resources, and environmental sciences for the Army, the Department of Defense, civilian agencies, and our nation’s public good. Find out more at www.erdc.usace.army.mil. To search for other technical reports published by ERDC, visit the ERDC online library at http://acwc.sdp.sirsi.net/client/default.Military Engineering Applied Research ERDC TR-17-2 May 2017 High-Fidelity Simulations of Electromagnetic Propagation and RF Communication Systems T53 Final Report Samuel S. Streeter, Daniel J. Breton, and Michele L. Maxson U.S. Army Engineer Research and Development Center (ERDC) Cold Regions Research and Engineering Laboratory (CRREL) 72 Lyme Road Hanover, NH 03755-1290 Christopher T. Goodin U.S. Army Engineer Research and Development Center (ERDC) Geotechnical and Structures Laboratory (GSL) 3909 Halls Ferry Road Vicksburg, MS 39180-6199 Final Report Approved for public release; distribution is unlimited. Prepared for U.S. Army Corps of Engineers Washington, DC 20314-1000 Under Military Engineering Technology PE 602784A, Project T53, "Material Characterization, Modeling, and Sensor Analytics" ERDC TR-17-2 ii Abstract Newly developed radio-frequency propagation models estimate signal strength, signal coverage, and bit error rates to support mission planning for robotic platforms operating in urban areas. This study involved high-fidelity modeling on a graphics processing unit workstation and included full th

Published
2017

32. Scattered signal distributions, parametric uncertainties, and Bayesian sequential updating.

Author

Wilson, D. Keith, Hart, Carl R., Pettit, Chris L., Breton, Daniel J., Nykaza, Edward T., and Ostashev, Vladimir E.

Abstract

A variety of probability density functions (pdfs) have been proposed for scattered signals, which have varying analytical advantages and ranges of physical applicability. We discuss here modeling with a compound pdf, in which a basic pdf, describing the underlying scattering process, has uncertain parameters or is modulated by variability in the environment. The parameters of the modulating pdf are termed hyperparameters. Some previous examples of compound formulations include the K-distribution, for which strong scattering (exponential pdf) is modulated by a gamma pdf for the mean signal power, and scattering by intermittent turbulence, for which strong scattering is modulated by a log-normal pdf for the structure-function parameter. We describe some alternative formulations, including strong scattering modulated by a gamma pdf for the inverse mean power, and Rytov (log-normal) scattering modulated by a normal pdf for the log-mean of the signal. These lead to relatively simple marginalized signal power distributions (Lomax and log-normal, respectively). Furthermore, the basic scattered signal pdf may be viewed as a likelihood function in which the modulating pdf is the Bayesian conjugate prior. Hence the hyperparameters of the modulating process can be refined by sequential Bayesian updating as additional transmission data become available. [ABSTRACT FROM AUTHOR]

Published
2017
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36. Instruments and Methods Design, optimization and calibration of an automated density gauge for firn and ice cores.

Author

Breton, Daniel J., Hamilton, Gordon S., and Hess, C. T.

Subjects
GAGES, ICE cores, GAMMA ray attenuation, DENSITY, MEASUREMENT, MASS attenuation coefficients, PHYSICAL measurements, MATHEMATICAL physics, ICE sheets
Abstract

The article discusses the instruments and methods used for firn and ice cores measurements. It focuses on the design, gamma-ray energy optimization and mass attenuation coefficient calibration of the Maine Automated Density Gauge Experiment (MADGE), a portable, field-operable gamma-ray density gauge which can provide high-resolution and high-precision density measurements. Major issues surrounding the gamma-ray density gauge design are described and details of the methods for determining the essential system parameters are also presented.

Published
2009
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