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  • Mechanical Engineering  (1)
  • Physicochemical  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 76 (1981), S. 69-79 
    ISSN: 1573-5117
    Keywords: Physicochemical ; fecal bacteria ; benthic macroinvertebrates ; diversity ; similarity ; discharge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Water quality of Menard Creek in the Big Thicket National Preserve of southeast Texas was studied from July 1978 to June, 1979 utilizing physicochemical parameters, bacteriological data, and benthic macroinvertebrates. Physicochemical conditions generally indicated good water quality. Dissolved oxygen concentrations were always high and all other parameters were within the expected ranges for small streams in this area. Conductivity and chlorides indicated low concentrations of oil field brines at Stations 4 and 5. Numbers of fecal bacteria were higher than acceptable at all stations during much of the study period. Highest numbers were generally found after heavy rains and surface runoff. Fecal coliform to fecal streptococci ratios indicated human contamination in 53 percent of the 60 samples, while non-human contamination was found in 12 percent of the samples. 125 taxa and 7,462 individuals of benthic macroinvertebrates were collected. Chironomids (44.8%, 38 sp.) and oligochaetes (32.1%, 13 sp.) were the dominant groups. The oligochaete Aulodrilus pigueti and the trichopterans Lype diversa and Brachycentrus numerosus were reported in Texas for the first time. The greatest number of taxa was found at Station 1 (79), while Station 5 had the fewest (61). Station 1 had the highest annual species diversity ({xxd}) of 4.37. The other stations had intermediate to high values indicating moderately stressed conditions during high discharge. Sørenson's (1948) index of similarity showed relatively high coefficients of faunal similarity between stations, depending on discharge.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2019-07-12
    Description: A multistage system has been proposed for cooling a circulating fluid that is subject to intermittent intense heating. The system would be both flexible and redundant in that it could operate in a basic passive mode, either sequentially or simultaneously with operation of a first, active cooling subsystem, and either sequentially or simultaneously with a second cooling subsystem that could be active, passive, or a combination of both. This flexibility and redundancy, in combination with the passive nature of at least one of the modes of operation, would make the system more reliable, relative to a conventional cooling system. The system would include a tube-in-shell heat exchanger, within which the space between the tubes would be filled with a phase-change material (PCM). The circulating hot fluid would flow along the tubes in the heat exchanger. In the basic passive mode of operation, heat would be conducted from the hot fluid into the PCM, wherein the heat would be stored temporarily by virtue of the phase change.
    Keywords: Mechanical Engineering
    Type: MSC-23652 , NASA Tech Briefs, August 2005; 22
    Format: application/pdf
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