35,358 research outputs found

    Tungsten-rhenium alloy thermocouples effective for high-temperature measurement

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    Tungsten-rhenium alloy thermocouples, specifically, insulated, sheathed W/W plus 26Re and W plus 5 Re/W plus 26 Re thermocouples, are effective for temperature measurement in excess of 2920 degrees C. These thermocouples have a high thermoelectric output and excellent relationship to temperatures up to 2760 degrees C

    Stranded superconducting cable of improved design

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    High-current cable developed in liquid helium cooled magnets uses aluminum wire interspersed with the superconductor strands. The aluminum maintains higher electrical conductivity, is light in weight, and has low thermal capacity

    Directly comparing coronal and solar wind elemental fractionation

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    As the solar wind propagates through the heliosphere, dynamical processes irreversibly erase the signatures of the near-Sun heating and acceleration processes. The elemental fractionation of the solar wind should not change during transit however, making it an ideal tracer of these processes. We aimed to verify directly if the solar wind elemental fractionation is reflective of the coronal source region fractionation, both within and across different solar wind source regions. A backmapping scheme was used to predict where solar wind measured by the Advanced Composition Explorer (ACE) originated in the corona. The coronal composition measured by the Hinode Extreme ultraviolet Imaging Spectrometer (EIS) at the source regions was then compared with the in-situ solar wind composition. On hourly timescales there was no apparent correlation between coronal and solar wind composition. In contrast, the distribution of fractionation values within individual source regions was similar in both the corona and solar wind, but distributions between different sources have significant overlap. The matching distributions directly verifies that elemental composition is conserved as the plasma travels from the corona to the solar wind, further validating it as a tracer of heating and acceleration processes. The overlap of fractionation values between sources means it is not possible to identify solar wind source regions solely by comparing solar wind and coronal composition measurements, but a comparison can be used to verify consistency with predicted spacecraft-corona connections.Comment: Accepted version; 8 pages, 7 figure

    Study of the use of Metal-Oxide-Silicon (MOS) devices for particulate detection and monitoring in the earth's atmosphere

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    A metal-oxide-silicon (MOS) capacitor-type particulate sensor was evaluated for use in atmospheric measurements. An accelerator system was designed and tested for the purpose of providing the necessary energy to trigger the MOS-type sensor. The accelerator system and the MOS sensor were characterized as a function of particle size and velocity. Diamond particles were used as particulate sources in laboratory tests. Preliminary tests were performed in which the detector was mounted on an aircraft and flown in the vicinity of coal-fired electric generating plants

    The Role of Cold Flows in the Assembly of Galaxy Disks

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    We use high resolution cosmological hydrodynamical simulations to demonstrate that cold flow gas accretion, particularly along filaments, modifies the standard picture of gas accretion and cooling onto galaxy disks. In the standard picture, all gas is initially heated to the virial temperature of the galaxy as it enters the virial radius. Low mass galaxies are instead dominated by accretion of gas that stays well below the virial temperature, and even when a hot halo is able to develop in more massive galaxies there exist dense filaments that penetrate inside of the virial radius and deliver cold gas to the central galaxy. For galaxies up to ~L*, this cold accretion gas is responsible for the star formation in the disk at all times to the present. Even for galaxies at higher masses, cold flows dominate the growth of the disk at early times. Within this modified picture, galaxies are able to accrete a large mass of cold gas, with lower initial gas temperatures leading to shorter cooling times to reach the disk. Although star formation in the disk is mitigated by supernovae feedback, the short cooling times allow for the growth of stellar disks at higher redshifts than predicted by the standard model.Comment: accepted to Ap
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