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Jones, Stephen

Publications and source records attributed to Jones, Stephen.

10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

FIREWHEEL

SAND2024-16910O FIREWHEEL is a tool for experiment orchestration that assists a user in building and controlling repeatable experiments of distributed network systems at any scale. This version also includes FIREWHEEL v2.7 and its associated companion model components. With FIREWHEEL, users can easily construct modular parts of a cyber system, called Model Components. The Model Components can be combined to form an experiment. Most experiments are then instantiated using an emulation tool, such as minimega.

Kajder, Thomas↗
DOE OSTI2023

TWST Cloud Properties (COD, droplet effective radius, and thermodynamic phase). SAIL, AMF2, 2022-2023.

The dataset consists of calibrated zenith shortwave spectral radiances (440-1700 nm) and cloud optical depth (COD) retrievals approximately every second. Retrievals of cloud droplet effective radius and thermodynamic phase are currently done offline, but some of these retrievals are included in the dataset. Effective radius and phase are included for days with periods of sufficiently high COD. Effective radius and phase retrievals in the data set were computed at approximately 5-10 second intervals to reduce computation time. The retrievals can be performed at the full sample rate. The field of view is 0.5 degree.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Machine learning and LHC event generation

First-principle simulations are at the heart of the high-energy physics research program. They link the vast data output of multi-purpose detectors with fundamental theory predictions and interpretation. This review illustrates a wide range of applications of modern machine learning to event generation and simulation-based inference, including conceptional developments driven by the specific requirements of particle physics. New ideas and tools developed at the interface of particle physics and machine learning will improve the speed and precision of forward simulations, handle the complexity of collision data, and enhance inference as an inverse simulation problem.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Development of arsenic doped Cd(Se,Te) absorbers by MOCVD for thin film solar cells

Recent developments in CdTe solar cell technology have included the incorporation of ternary alloy Cd(Se,Te) in the devices. CdTe absorber band gap grading due to Se alloying contributes to current density enhancement and can result in device performance improvement. Here we report Cd(Se,Te) polycrystalline thin films grown by a chamberless inline atmospheric pressure metal organic chemical vapour deposition technique, with subsequent incorporation in CdTe solar cells. The compositional dependence of the crystal structure and optical properties of Cd(Se,Te) are examined. Selenium graded Cd(Se,Te)/CdTe absorber structure in devices are demonstrated using either a single CdSe layer or CdSe/Cd(Se,Te) bilayer (with or without As doping in the Cd(Se,Te) layer). Cross-sectional TEM/EDS, photoluminescence spectra and secondary ion mass spectroscopy analysis confirmed the formation of a graded Se profile toward the back contact with a diffusion length of ~1.5 um and revealed back-diffusion of Group V (As) dopants from the CdTe layer into Cd(Se,Te) grains. Due to the strong Se/Te interdiffusion, CdSe in the Se bilayer configuration was unable to form an n-type emitter layer in processed devices. In situ As doping of the Cd(Se,Te) layer benefited the device junction quality with current density reaching 28.3 mA/cm 2 . The results provide useful insights for the optimisation of Cd(Se,Te)/CdTe solar cells.

14 SOLAR ENERGY↗
DOE OSTI2020

Power-to-Gas System Valuation. Final Report

To provide a framework for evaluating the technical and financial benefits of a power-to-gas (P2G) system deployed in the Holyoke Gas and Electric (HG&E) system, Pacific Northwest National Laboratory modified its energy storage valuation tools to run a one-year simulation of P2G operations. The simulation was used to evaluate the benefits of P2G for multiple grid and industrial applications over the economic life of the unit, or units, depending on the asset configuration.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2020

Cloud Shortwave Optical Properties

The data set consists of calibrated zenith shortwave spectral radiances (400-950 nm and 940-1665 nm) and cloud optical depth (COD) retrievals every 2 seconds. The field of view is 0.5 degree. Retrievals of cloud droplet effective radius and thermodynamic phase are currently experimental and done offline. Effective radius and phase are not in this data set.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2019

Two-Point Focused Laser Differential Interferometry Second-Mode Measurements at Mach 6

A two-point focused laser differential interferometer (FLDI) is used to make measurements of density fluctuations on a 7 degree half-angle cone in a Mach 6 flow. The system was first characterized in the laboratory using laser induced breakdown to provide a well defined density fluctuation. The speed of the shock wave generated by the breakdown is verified using simultaneous high-speed schlieren. The FLDI system is then installed at the NASA Langley 20-Inch Mach 6 air tunnel to make measurements in the boundary layer of the 7 degree half-angle cone model and in the tunnel freestream for a unit Reynolds number range of 3.0 to 8.22 x 10(exp 6)/ft. Second-mode packets are visible in the spectra, with peak frequencies increasing linearly and peak amplitude increasing as a function of unit Reynolds number. The two-point measurement allows for the calculation of the second-mode wavepacket speeds, which propagate between 88% and 92% of the freestream velocity of the tunnel for all Reynolds numbers. The FLDI measurements are compared to surface-mounted fast-response pressure transducer measurements, where second-mode frequencies and wavepacket speeds are in good agreement.

Weisberger, Joshua M.↗
NASA NTRS2019

Comparison of Design Tools for Stress Analysis of Adhesively Bonded Joints

Analytical or semi-analytical models for stress analysis have long been a part of initial adhesive bond design and sizing. Even with the rise of general finite element software and methods, these design models have still remained a preferred method for fast and simple joint analysis. While these methods can yield fairly representative results, the models are constructed on the foundation of geometrical and material simplifications or assumptions that allow closed form or semi-closed form solutions. This study outlines the major differences in basic assumptions for three common design software packages under use at NASA, and shows the ramifications these assumptions in a few exemplar bonded joints.

Composites↗
NASA NTRS2015

Development of Background-Oriented Schlieren for NASA Langley Research Center Ground Test Facilities

This paper provides an overview of recent wind tunnel tests performed at the NASA Langley Research Center where the Background-Oriented Schlieren (BOS) technique was used to provide information pertaining to flow-field density disturbances. The facilities in which the BOS technique was applied included the National Transonic Facility (NTF), Transonic Dynamics Tunnel (TDT), 31-Inch Mach 10 Air Tunnel, 15-Inch Mach 6 High-Temperature Air Tunnel, Rotor Test Cell at the 14 by 22 Subsonic Tunnel, and a 13-Inch Low-Speed Tunnel.

Bathel, Brett F.↗