68 research outputs found
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An apparatus to measure frictional, inelastic, and viscous behavior in ice at temperate and planetary conditions
In this paper, we describe a cryogenic, servo-controlled biaxial friction apparatus designed to measure the deformational behaviors of ice. The apparatus is specifically designed to accurately achieve and measure the low differential stresses applicable to deforming ice on earth and on icy satellites. We can apply loads in the range ∼2–1800 kPa and velocities up to 4 mm/s, with resolution of 39 Pa and 0.7 μm, respectively. Precise temperature control, measurement, and insulation allow testing at constant temperature (from −2 to −30 °C) for prolonged periods of time. The apparatus is tested with various plastics as well as with polycrystalline ice samples and the results are consistent with previously published values. Critical components of the instrument are described along with examples of data collection schemes and preliminary results. The flexibility of the design allows for both glaciological and planetary applications over a range of deformational behaviors including friction, anelastic, and viscous
Aerodynamic Electrical Energy: Wind Turbine Engineering
Renewable resources such as wind, solar, and water, are important in energy production. This project was to design a wind turbine electricity generation system and gain an understanding of the engineering involved in producing electricity from the wind. Having observed the wind patterns on the campus of Utah State University, it was decided to obtain both a horizontal axis (HAWT) and a vertical axis wind turbine (VAWT) and mount them on the roof of the USU Dean F. Peterson, Jr. Engineering Laboratory Building. The outputs of both turbines were measured and compared. For the low wind conditions of Logan, Utah, the HAWT was found to be the most effective
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Acoustic and Microstructural Properties of Partially Molten Samples in the Ice-Ammonia System
We measured the ultrasonic properties and the microstructure of two-phase binary mixtures of the ice-ammonia partial melt system, which was selected based on its importance for numerous planetary bodies. The equilibrium microstructure of ice-ammonia melt was examined using a light microscope within a cold room. The measured median dihedral angle between the solid and melt at 256 K is approximately 63deg, with a broad distribution of observed angles. P-wave velocities in the partially molten samples were measured as a function of temperature and composition. We compare the results of this study to those of other potential binary systems by normalizing the datasets using a vertical lever and articulating the potential effects on the mechanical behavior and transport capabilities of partially molten ice in icy satellites
Layered architecture for quantum computing
We develop a layered quantum computer architecture, which is a systematic
framework for tackling the individual challenges of developing a quantum
computer while constructing a cohesive device design. We discuss many of the
prominent techniques for implementing circuit-model quantum computing and
introduce several new methods, with an emphasis on employing surface code
quantum error correction. In doing so, we propose a new quantum computer
architecture based on optical control of quantum dots. The timescales of
physical hardware operations and logical, error-corrected quantum gates differ
by several orders of magnitude. By dividing functionality into layers, we can
design and analyze subsystems independently, demonstrating the value of our
layered architectural approach. Using this concrete hardware platform, we
provide resource analysis for executing fault-tolerant quantum algorithms for
integer factoring and quantum simulation, finding that the quantum dot
architecture we study could solve such problems on the timescale of days.Comment: 27 pages, 20 figure
The Science Performance of JWST as Characterized in Commissioning
This paper characterizes the actual science performance of the James Webb
Space Telescope (JWST), as determined from the six month commissioning period.
We summarize the performance of the spacecraft, telescope, science instruments,
and ground system, with an emphasis on differences from pre-launch
expectations. Commissioning has made clear that JWST is fully capable of
achieving the discoveries for which it was built. Moreover, almost across the
board, the science performance of JWST is better than expected; in most cases,
JWST will go deeper faster than expected. The telescope and instrument suite
have demonstrated the sensitivity, stability, image quality, and spectral range
that are necessary to transform our understanding of the cosmos through
observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures;
https://iopscience.iop.org/article/10.1088/1538-3873/acb29
New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk
To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P<5 × 10−8), of which eight were previously associated with increased overall adiposity (BMI, BF%) and four (in or near COBLL1/GRB14, IGF2BP1, PLA2G6, CRTC1) were novel associations with BF%. Seven loci showed a larger effect on BF% than on BMI, suggestive of a primary association with adiposity, while five loci showed larger effects on BMI than on BF%, suggesting association with both fat and lean mass. In particular, the loci more strongly associated with BF% showed distinct cross-phenotype association signatures with a range of cardiometabolic traits revealing new insights in the link between adiposity and disease risk
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