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Analysis of Tempered Fractional Operators

D'Elia, Marta D.; Olson, Hayley

Tempered fractional operators are useful in models for subsurface transport and diffusion due to their ability to capture anomalous diffusion: a behavior which the classical partial differential equation models cannot describe. We analyze tempered fractional operators within the nonlocal vector calculus framework in order to assimilate them to the rigorous mathematical structure developed for nonlocal models. First, we show they are special instances of generalized nonlocal operators in correspondence of a proper choice of nonlocal kernels. Then, we work towards showing tempered fractional operators are equivalent to truncated fractional operators. These truncated operators are useful because they are less computationally intensive than the tempered operators.

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TYPE Other Report YEAR 2020
DOIOSTI

Using Raman scattering to study reacting gas flow over a catalyst

Ungar, Alexander U.

l present a series of computational methods for analyzing and correcting Raman scattering from a reacting gas flow. My work focused on the laser diagnostic measurements of formaldehyde production over a silver catalyst, specifically the Raman spectroscopy component. This technique offers a non-intrusive, in situ way to measure the coupling between the gas phase and surface activity of a catalytic reaction at relevant industrial conditions. This report outlines the steps followed for correcting the non-idealities in the data due to both the detection optics and scattering mechanics. By implementing such refinement steps, l can generate an accurate 2D spatial map of the temperature profile, number densities for major species, and relative consumption of reactants throughout the reactor cell.

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TYPE Other Report YEAR 2020
DOIOSTI

Nanoantenna-Enhanced Resonant Detectors for Improved Infrared Detector Performance

Goldflam, Michael G.; Anderson, Evan M.; Fortune, Torben R.; Klem, John F.; Hawkins, Samuel D.; Davids, Paul D.; Campione, Salvatore; Pung, Aaron J.; Webster, Preston T.; Weiner, Phillip; Finnegan, Patrick S.; Wendt, Joel; Wood, Michael G.; Haines, Chris; Coon, Wesley T.; Olesberg, Jonathon T.; Shaner, Eric A.; Kadlec, Clark N.; Laros, James H.; Sinclair, Michael B.; Tauke-Pedretti, Anna; Kim, Jin K.; Peters, D.W.

Abstract not provided.

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TYPE Conference Poster YEAR 2020
OSTI

Propagation of a Stress Pulse in a Heterogeneous Elastic Bar

Silling, Stewart A.

The propagation of a wave pulse due to low-speed impact on a one-dimensional, heterogeneous bar is studied. Due to the dispersive character of the medium, the pulse attenuates as it propagates. This attenuation is studied over propagation distances that are much longer than the size of the microstructure. A homogenized peridynamic material model can be calibrated to reproduce the attenuation and spreading of the wave. The calibration consists of matching the dispersion curve for the heterogeneous material in the limit of long and moderately long wavelengths. It is demonstrated that the peridynamic method reproduces the attenuation of wave pulses predicted by an exact microstructural model over large propagation distances.

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TYPE SAND Report YEAR 2020
DOIOSTI

New Generation Multijunction Thermal Converters at Sandia National Laboratories

CPEM Digest (Conference on Precision Electromagnetic Measurements)

Johnson, Raegan L.; Meyrick, Aaron; Dominguez, Jason J.; Lukes, Karl L.; Stanford, Joshua S.; Cular, Stefan; O'Brien, Edward O.

Multijunction thermal converters are routinely used at many primary standards laboratories for ac voltage measurements and calibrations. After nearly two decades of inactivity, the Primary Standards Laboratory at Sandia National Laboratories has reestablished the process of fabricating silicon based multijunction thermal converters. Initial results indicate the devices perform similarly to devices fabricated circa 2001 with ac-dc differences of less than 2 mu mathrm{V}/mathrm{V} over the frequency range of 20 Hz to 20 kHz. From 20 kHz to 1 MHz, the ac-dc difference was higher, but remained below 200 mu mathrm{V}/mathrm{V}. In addition to presenting these results, new design considerations, such as high-resistivity substrates for high-frequency applications, are discussed.

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TYPE Conference Poster YEAR 2020
OSTIScopus

Environmental permitting and compliance cost reduction strategies for the MHK industry: Lessons learned from other industries

Journal of Marine Science and Engineering

Kramer, Sharon; Jones, Craig; Klise, Geoffrey T.; Roberts, Jesse D.; West, Anna; Barr, Zach

The marine and hydrokinetic (MHK) industry plays a vital role in the U.S. clean energy strategy by providing a renewable, domestic energy source that may offset the need for traditional energy sources. The first MHK deployments in the U.S. have incurred very high permitting costs and long timelines for deploying projects, which increases project risk and discourages investment. A key challenge to advancing an economically competitive U.S. MHK industry is reducing the time and cost required for environmental permitting and compliance with government regulations. Other industries such as offshore oil and gas, offshore wind energy, subsea power and data cables, onshore wind energy, and solar energy facilities have all developed more robust permitting and compliance pathways that provide lessons for the MHK industry in the U.S. and may help inform the global consenting process. Based on in-depth review and research into each of the other industries, we describe the environmental permitting pathways, the main environmental concerns and types of monitoring typically associated with them, and factors that appear to have eased environmental permitting and compliance issues.

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TYPE Journal Article YEAR 2020
DOIOSTIScopus
Results 14601–14800 of 96,771
Results 14601–14800 of 96,771