177 research outputs found
Blade design and operating experience on the MOD-OA 200 kW wind turbine at Clayton, New Mexico
Two 60 foot long aluminum wind turbine blades were operated for over 3000 hours on the MOD-OA wind turbine. The first signs of blade structural damage were observed after 400 hours of operation. Details of the blade design, loads, cost, structural damage, and repair are discussed
Aluminum blade development for the Mod-OA 200-kilowatt wind turbine
The rotor blade configuration, fabrication methods, analyses, operating experience, design modifications, and cost are described. Each 60-ft.-(18.3-m-) long aluminum blade used current aircraft fixed wing and rotary wing design and fabrication technologies. Structural damage, repairs, and modifications that occurred during 6500 hours of operation are summarized
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Aluminum-blade development for the Mod-0A 200-kilowatt wind turbine
This report documents the operating experience with two aluminum blades used on the DOE/NASA Mod-0A 200-kilowatt wind turbine located at Clayton, New Mexico. Each Mod-0A aluminum blade is 59.9 feet long and weighs 2360 pounds. The aluminum Mod-0A blade design requirements, the selected design, fabrication procedures, and the blade analyses are discussed. A detailed chronology is presented on the operating experience of the Mod-0A aluminum blades used at Clayton, New Mexico. Blade structural damage was experienced. Inspection and damage assessment were required. Structural modifications that were incorporated to the blades successfully extended the useful operating life of the blades. The aluminum blades completed the planned 2 years of operation of the Clayton wind turbine. The blades were removed from service in August 1980 to allow testing of advanced technology wood composite blades
High-throughput determination of Hubbard U and Hund J values for transition metal oxides via linear response formalism
DFT+U provides a convenient, cost-effective correction for the
self-interaction error (SIE) that arises when describing correlated electronic
states using conventional approximate density functional theory (DFT). The
success of a DFT+U(+J) calculation hinges on the accurate determination of its
Hubbard U and Hund's J parameters, and the linear response (LR) methodology has
proven to be computationally effective and accurate for calculating these
parameters. This study provides a high-throughput computational analysis of the
U and J values for transition metal d-electron states in a representative set
of over 2000 magnetic transition metal oxides (TMOs), providing a frame of
reference for researchers who use DFT+U to study transition metal oxides. In
order to perform this high-throughput study, an atomate workflow is developed
for calculating U and J values automatically on massively parallel
supercomputing architectures. To demonstrate an application of this workflow,
the spin-canting magnetic structure and unit cell parameters of the
multiferroic olivine LiNiPO4 are calculated using the computed Hubbard U and
Hund J values for Ni-d and O-p states, and are compared with experiment. Both
the Ni-d U and J corrections have a strong effect on the Ni-moment canting
angle. Additionally, including a O-p U value results in a significantly
improved agreement between the computed lattice parameters and experiment.Comment: 18 pages, 6 figure
Middle Neolithic pits and a burial at West Amesbury, Wiltshire
Excavations on the south-eastern slopes of King Barrow Ridge, 1.5 km east of Stonehenge, revealed five pits, a grave and other features of Middle Neolithic date. Analysis of the pit assemblages and the partial inhumation interred in the grave has provided insights into lifeways in this landscape in the late fourth millennium cal BC. Evidence suggests that the area was visited by a pastoralist, mobile community on a semi-regular basis for a significant period, in late autumn or winter. Selected remnants of craft-working and consumption were deposited in pits, before deliberate infilling. These depositions repeatedly memorialised activity on the hillside at a time of contemporary activity elsewhere on King Barrow Ridge and at the future site of Stonehenge. Middle Neolithic pits are present in significant numbers across King Barrow Ridge, and alongside pits in the Durrington area, form one of the densest concentrations of such activity in the region. Long distance mobility is suggested by the possible Irish origins of the inhumation, the first Middle Neolithic individual excavated in the environs of Stonehenge. Whilst of significance for understanding the Middle Neolithic in the WHS and the region, this research also hints at the roots of Late Neolithic monumentalisation of this landscape
Inflight Radiometric Calibration of New Horizons' Multispectral Visible Imaging Camera (MVIC)
We discuss two semi-independent calibration techniques used to determine the
in-flight radiometric calibration for the New Horizons' Multi-spectral Visible
Imaging Camera (MVIC). The first calibration technique compares the observed
stellar flux to modeled values. The difference between the two provides a
calibration factor that allows the observed flux to be adjusted to the expected
levels for all observations, for each detector. The second calibration
technique is a channel-wise relative radiometric calibration for MVIC's blue,
near-infrared and methane color channels using observations of Charon and
scaling from the red channel stellar calibration. Both calibration techniques
produce very similar results (better than 7% agreement), providing strong
validation for the techniques used. Since the stellar calibration can be
performed without a color target in the field of view and covers all of MVIC's
detectors, this calibration was used to provide the radiometric keywords
delivered by the New Horizons project to the Planetary Data System (PDS). These
keywords allow each observation to be converted from counts to physical units;
a description of how these keywords were generated is included. Finally,
mitigation techniques adopted for the gain drift observed in the near-infrared
detector and one of the panchromatic framing cameras is also discussed
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