Engineering topics

Wright, Jason

Publications and source records attributed to Wright, Jason.

9 records

DOE OSTI2019

Electromagnetic analysis and experimental testing of a flux focusing wind turbine magnetic gearbox

The electromagnetic design of the second stage of a 59:1 multistage magnetic gearbox for a wind turbine demonstrator is presented here. The multistage series connected magnetic gearbox is composed of a 6.45:1 first stage and 9.14:1 second stage magnetic gear. The magnetic gears utilize a flux focusing spoke type rotor typology with a unique segmented fully laminated design. The electromagnetic impact of structural design changes on the second stage gearbox is considered with respect to torque density. Severe 3-D edge effects were encountered that greatly reduced the expect torque density of the stage 2 magnetic gear. Experimental testing of the multistage magnetic gear highlight unexpected problems associated with eddy current loss and torque ripple.

17 WIND ENERGY↗

DOE OSTI2019

Designing and Experimentally Testing a Magnetic Gearbox for a Wind Turbine Demonstrator

Here, the design of the first stage of a 59:1 multistage magnetic gearbox for a wind turbine demonstrator is presented here. The multistage magnetic gearbox (MSMG) is composed of a two stage magnetic gearbox (MG). The first stage of the MSMG has a gear ratio of 6.45. A spoke type MG rotor typology is used with a unique segmented fully laminated rotor structure. Axial-ly segmented magnets and a unique set of radial deflection rotor support rings are utilized. Design issues with respect to losses and torque ripple are highlighted.

17 WIND ENERGY↗

DOE OSTI2018

Investigating the Performance of a Fully Laminated Flux-Focusing Magnetic Gearbox

This paper presents here the design investigation and experimental testing of a flux-focusing magnetic gearbox with a fully laminated rotor structure. The unique feature of this flux-focusing magnetic gearbox design is that the three rotors are each made of a single lamination stack, and the central modulation structure is retained in place without the use of a resin filler such as epoxy. Ferromagnetic bridges are used to connect individual pole pieces together. It is shown that the use of the ferromagnetic bridges reduces the calculated torque density from 156 Nm/L to 139 Nm/L (a reduction of 11%). The experimentally measured torque density is, however, only 97 Nm/L. The reason for this discrepancy is associated with the demagnetization of the magnets.

42 ENGINEERING↗

NASA NTRS2018

The NEID Precision Radial Velocity Spectrometer: Port Adapter Overview, Requirements, and Test Plan

The NEID spectrometer is an optical (380-930 nm), fiber-fed, precision Doppler spectrometer currently in development for the WIYN 3.5 m telescope at Kitt Peak National Observatory as part of the NN-EXPLORE partnership. Designed to achieve a radial velocity precision of < 30 cm/s, NEID will be sensitive enough to detect terrestrial-mass exoplanets around low-mass stars. Light from the target stars is focused by the telescope to a bent Cassegrain port at the edge of the primary mirror mechanical support. The specialized NEID "Port Adapter" system is mounted at this bent Cassegrain port and is responsible for delivering the incident light from the telescope to the NEID fibers. In order to provide stable, high-quality images to the science instrument, the Port Adapter houses several sub-components designed to acquire the target stars, correct for atmospheric dispersion, stabilize the light onto the science fibers, and calibrate the spectrometer by injecting known wavelength sources such as a laser frequency comb. Here we provide an overview of the overall opto-mechanical design and system requirements of the Port Adapter. We also describe the development of system error budgets and testplans to meet those requirements.

Cassegrain port↗

DOE OSTI2017

Toward Space-like Photometric Precision from the Ground with Beam-shaping Diffusers

We demonstrate a path to hitherto unachievable differential photometric precisions from the ground, both in the optical and near-infrared (NIR), using custom-fabricated beam-shaping diffusers produced using specialized nanofabrication techniques. Such diffusers mold the focal plane image of a star into a broad and stable top-hat shape, minimizing photometric errors due to non-uniform pixel response, atmospheric seeing effects, imperfect guiding, and telescope-induced variable aberrations seen in defocusing. This PSF reshaping significantly increases the achievable dynamic range of our observations, increasing our observing efficiency and thus better averages over scintillation. Diffusers work in both collimated and converging beams. We present diffuser-assisted optical observations demonstrating 62{sub −16}{sup +26} ppm precision in 30 minute bins on a nearby bright star 16 Cygni A (V = 5.95) using the ARC 3.5 m telescope—within a factor of ∼2 of Kepler's photometric precision on the same star. We also show a transit of WASP-85-Ab (V = 11.2) and TRES-3b (V = 12.4), where the residuals bin down to 180{sub −41}{sup +66} ppm in 30 minute bins for WASP-85-Ab—a factor of ∼4 of the precision achieved by the K2 mission on this target—and to 101 ppm for TRES-3b. In the NIR, where diffusers may provide even more significant improvements over the current state of the art, our preliminary tests demonstrated 137{sub −36}{sup +64} ppm precision for a K {sub S} = 10.8 star on the 200 inch Hale Telescope. These photometric precisions match or surpass the expected photometric precisions of TESS for the same magnitude range. This technology is inexpensive, scalable, easily adaptable, and can have an important and immediate impact on the observations of transits and secondary eclipses of exoplanets.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2017

Analysis and Testing of a Coaxial Magnetic Gearbox With Flux Concentration Halbach Rotors

Halbach array magnetic gearboxes have been discussed as being able to create high torque density. However, Halbach arrays are difficult to mechanically assemble, and often the effective air gap must be made larger to provide space for a retaining sleeve. This paper investigates here the benefits of using an additional ferromagnetic retaining pole within the Halbach array structure. It is shown that utilizing this flux concentration ferromagnetic pole improves the torque density and can also help retain the magnets in place.

42 ENGINEERING↗

NASA NTRS2016

A Comprehensive Radial Velocity Error Budget for Next Generation Doppler Spectrometers

We describe a detailed radial velocity error budget for the NASA-NSF Extreme Precision Doppler Spectrometer instrument concept NEID (NN-explore Exoplanet Investigations with Doppler spectroscopy). Such an instrument performance budget is a necessity for both identifying the variety of noise sources currently limiting Doppler measurements, and estimating the achievable performance of next generation exoplanet hunting Doppler spectrometers. For these instruments, no single source of instrumental error is expected to set the overall measurement floor. Rather, the overall instrumental measurement precision is set by the contribution of many individual error sources. We use a combination of numerical simulations, educated estimates based on published materials, extrapolations of physical models, results from laboratory measurements of spectroscopic subsystems, and informed upper limits for a variety of error sources to identify likely sources of systematic error and construct our global instrument performance error budget. While natively focused on the performance of the NEID instrument, this modular performance budget is immediately adaptable to a number of current and future instruments. Such an approach is an important step in charting a path towards improving Doppler measurement precisions to the levels necessary for discovering Earth-like planets.

NASA-NSF Extreme Precision Doppler Spectrometer in↗

DOE OSTI2012

Mining Bug Databases for Unidentified Software Vulnerabilities

Identifying software vulnerabilities is becoming more important as critical and sensitive systems increasingly rely on complex software systems. It has been suggested in previous work that some bugs are only identified as vulnerabilities long after the bug has been made public. These vulnerabilities are known as hidden impact vulnerabilities. This paper discusses the feasibility and necessity to mine common publicly available bug databases for vulnerabilities that are yet to be identified. We present bug database analysis of two well known and frequently used software packages, namely Linux kernel and MySQL. It is shown that for both Linux and MySQL, a significant portion of vulnerabilities that were discovered for the time period from January 2006 to April 2011 were hidden impact vulnerabilities. It is also shown that the percentage of hidden impact vulnerabilities has increased in the last two years, for both software packages. We then propose an improved hidden impact vulnerability identification methodology based on text mining bug databases, and conclude by discussing a few potential problems faced by such a classifier.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2012

DETECTION OF K{sub S} -BAND THERMAL EMISSION FROM WASP-3b

We report the detection of thermal emission from the hot Jupiter WASP-3b in the K{sub S} band, using a newly developed guiding scheme for the WIRC instrument at the Palomar Hale 200 inch telescope. Our new guiding scheme has improved the telescope guiding precision by a factor of {approx}5-7, significantly reducing the correlated systematics in the measured light curves. This results in the detection of a secondary eclipse with depth of 0.181% {+-} 0.020% (9{sigma})-a significant improvement in WIRC's photometric precision and a demonstration of the capability of Palomar/WIRC to produce high-quality measurements of exoplanetary atmospheres. Our measured eclipse depth cannot be explained by model atmospheres with heat redistribution but favors a pure radiative equilibrium case with no redistribution across the surface of the planet. Our measurement also gives an eclipse phase center of 0.5045 {+-} 0.0020, corresponding to an ecos {omega} of 0.0070 {+-} 0.0032. This result is consistent with a circular orbit, although it also suggests that the planet's orbit might be slightly eccentric. The possible non-zero eccentricity provides insight into the tidal circularization process of the star-planet system, but might also have been caused by a second low-mass planet in the system, as suggested by a previous transit timing variation study. More secondary eclipse observations, especially at multiple wavelengths, are necessary to determine the temperature-pressure profile of the planet's atmosphere and shed light on its orbital eccentricity.

79 ASTRONOMY AND ASTROPHYSICS↗