2,780 research outputs found

    Contamination control program for the Cosmic Background Explorer: An overview

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    Each of the three state of the art instruments flown aboard NASA's Cosmic Background Explorer (COBE) were designed, fabricated, and integrated using unique contamination control procedures to ensure accurate characterization of the diffuse radiation in the universe. The most stringent surface level cleanliness specifications ever attempted by NASA were required by the Diffuse Infrared Background Experiment (DRIBE) which is located inside a liquid helium cooled dewar along with the Far Infrared Absolute Spectrophotometer (FIRAS). The DRIBE instrument required complex stray radiation suppression that defined a cold primary optical baffle system surface cleanliness level of 100A. The cleanliness levels of the cryogenic FIRAS instrument and the Differential Microwave Radiometer (DMR) which were positioned symmetrically around the dewar were less stringent ranging from 300 to 500A. To achieve these instrument cleanliness levels, the entire flight spacecraft was maintained at level 500A throughout each phase of development. The COBE contamination control program is described along with the difficulties experienced in maintaining the cleanliness quality of personnel and flight hardware throughout instrument assembly

    Cryogenic shutter

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    A magnetically operated shutter mechanism is provided that will function in cryogenic or cryogenic zero gravity environments to selectively block radiation such as light from passing through a window to a target object such as a mirror or detector located inside a cryogenic container such as a dewar. The mechanism includes a shutter paddle blade that is moved by an electromagnetically actuated torquing device between an open position where the target object is exposed to ambient radiation or light and a closed position where the shutter paddle blade shields the ambient radiation or light from the target object. The purpose of the shuttering device is to prevent the mirror or other target object from being directly exposed to radiation passing through the window located on the side wall of the dewar, thereby decreasing or eliminating any temperature gradient that would occur within the target object due to exposure to the radiation. A special nylon bearing system is utilized to prevent the device from binding during operation and the paddle blade is also thermally connected to a reservoir containing cryogen to further reduce the internal temperature

    Integrating Fire with Land Management Planning and Action-A Process

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    Adapted from a paper presented at the Joint Rocky Mountain Fire Council and Intermountain Fire Research Council Meeting, Rangeland Management and Fire, Casper, Wyoming, November 1, 2, 3, 1977

    Study of educational forest fire prevention media in western Montana

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    Spectral statistics of a minimal quantum glass model

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    Glasses have the interesting feature of being neither integrable nor fully chaotic. They thermalize quickly within a subspace but thermalize much more slowly across the full space due to high free energy barriers which partition the configuration space into sectors. Past works have examined the Rosenzweig-Porter (RP) model as a minimal quantum model which transitions from localized to chaotic behavior. In this work we generalize the RP model in such a way that it becomes a minimal model which transitions from glassy to chaotic behavior, which we term the "Block Rosenzweig-Porter" (BRP) model. We calculate the spectral form factors of both models at all timescales. Whereas the RP model exhibits a crossover from localized to ergodic behavior at the Thouless timescale, the new BRP model instead crosses over from glassy to fully chaotic behavior, as seen by a change in the slope of the ramp of the spectral form factor.Comment: 41 pages, 10 figure

    An Analysis of the Long-Term Salinity Patterns in the Louisiana Coastal Zone

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    Saltwater intrusion is believed to be one of the greatest threats to Louisiana\u27s fishery and wildlife resources. The Louisiana Department of Wildlife and Fisheries has maintained salinity recording stations throughout the state\u27s coastal marshes since the 1960\u27s. We applied several different analytical approaches to the salinity data from 17 stations to determine whether this data base could be used to detect and quantity long-term salinity trends in coastal Louisiana. We did not detect a large-scale, consistent trend over time in coastal salinities across the state. Problems that hindered the detection of long-term trends included short periods of record and the placement of the recording stations in salt and brackish marsh areas, where we would not expect to find great changes in salinity. For the data to be useful in monitoring salinity trends in coastal marshes, especially with respect to saltwater intrusion, stations should be added in fresh and intermediate marshes. In addition, the relationships our study revealed between short- and long-term data indicate that records covering less than a decade are insufficient to denote long-term salinity changes, barring some major modification of the hydrologic regime

    Results from the Operational Testing of the General Electric Smart Grid Capable Electric Vehicle Supply Equipment (EVSE)

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    The Idaho National Laboratory conducted testing and analysis of the General Electric (GE) smart grid capable electric vehicle supply equipment (EVSE), which was a deliverable from GE for the U.S. Department of Energy FOA-554. The Idaho National Laboratory has extensive knowledge and experience in testing advanced conductive and wireless charging systems though INL’s support of the U.S. Department of Energy’s Advanced Vehicle Testing Activity. This document details the findings from the EVSE operational testing conducted at the Idaho National Laboratory on the GE smart grid capable EVSE. The testing conducted on the EVSE included energy efficiency testing, SAE J1772 functionality testing, abnormal conditions testing, and charging of a plug-in vehicle
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