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  • 1
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    Modelling probability of root disease center occurrence in northern Idaho forests (1982)
    Canadian Science Publishing
    Details
    Publication Date: 1982-12-01
    Description: A data screening algorithm (SCREEN) identified stand age, average stand diameter, timber type, soil type, aspect, habitat type, and elevation as forest stand or site characteristics strongly associated with root-disease occurrence in northern Idaho forests. The logistic regression model was used to predict root disease center occurrence. A second algorithm (RISK) was used to compute the estimates for the coefficients and to test different prediction equations. On wet aspects, highest probability of root disease centers was found on soils with lowest year-round moisture availability. The reverse was true on dry aspects. Increased slope was associated with increased root disease. Root disease center frequency was inversely related to elevation and directly related to occurrence of Pseudotsugamenziesii (Mirb.) Franco and Abiesgrandis (Dougl.) Lindl. Expression of disease centers was maximum at 60–100 years of stand age on all habitat types. A habitat-type–age interaction was observed in oldest aged stands.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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    PAPER CURRENT
  • 2
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    A system using aerial photography to estimate area of root disease centers in forests (1978)
    Canadian Science Publishing
    Details
    Publication Date: 1978-06-01
    Description: The area of root disease centers on the Coeur d'Alene National Forest in northern Idaho was effectively estimated from large-scale color infrared aerial photographs. An estimated 5.1% (12 160.7 ha) of the commercial forest land was occupied by infection centers. Root disease centers were identified in 113 of 364 stands actually surveyed. Although most of these 113 stands were of the Tsugaheterophylla – Pachistimamyrsinites habitat type, the highest percentage of stands with root disease was found in the Abiesgrandis – Pachistimamyrsinites habitat type.Observations made during these studies suggest that occurrence of Pseudotsugamenziesii (Mirb.) Franco, Abiesgrandis (Dougl.) Lindl., or both in a stand is the most important factor in the expression of root disease centers. Accuracy of interpretation of photographs was 92%; incorrect interpretations were consistently associated with stands in the Abieslasiocarpa series of habitat types or with stands stocked with conifers tolerant of root pathogens.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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    PAPER CURRENT
  • 3
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    Ignition of contaminants by impact of high-pressure oxygen (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The ignition of oil-film contaminants in high-pressure gaseous oxygen systems, caused by rapid pressurization, was investigated using the NASA/White Sands Test Facility's large-volume pneumatic impact test system. The test section consisted of stainless steel lines, contaminated on the inside surface with known amounts of Mobil DTE 24 oil and closed at one end, which was attached to a high-pressure oxygen system; the test section was pressurized to 48 MPa by opening a high-speed valve. Ignition of the oil was detected by a photocell attached to the closed end of the line. It was found that the frequency of ignition increased as a function of both the concentration of oil and of the pressure of the impacting oxygen. The threshold of ignition was between 25 and 65 mg/sq m. The results were correlated with the present NASA and Compressed Gas Association requirements for maximum levels of organic contaminants.
    Keywords: CHEMISTRY AND MATERIALS (GENERAL)
    Type: Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres; Apr 06, 1987 - Apr 08, 1987; Cambridge
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    ASTM Committee G-4 metals flammability test program - Data and discussion (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Results of metals flammability tests performed on twenty-six metals in the NASA/White Sands Test Facility are discussed together with the test systems. The promoted combustion and ignition characteristics of these metals are described, and the metals are ranked according to their suitability for use in oxygen systems. In general, alloys with high copper and nickel contents and low iron content were found to rank higher than those that had high iron content, while alloys that had high aluminum content were ranked the lowest.
    Keywords: METALLIC MATERIALS
    Type: Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres; Apr 06, 1987 - Apr 08, 1987; Cambridge
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    NASA TECHNICAL REPORTS
  • 5
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    Ignition of nonmetallic materials by impact of high-pressure gaseous oxygen (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The sources of variability in the pneumatic impact test commonly used to screen nonmetallic materials for oxygen service and to rank batches or lots of particular materials were investigated together with the mechanism of ignition. Tests were conducted at the NASA/White Sands Test Facility in which the standard test chamber was replaced by an instrumented chamber to obtain information on the rates of pressurization, specimen heating, and time to ignition. Results showed that much of the variability in test data could be traced to the variability in system cleanliness and in the opening time of the high-speed valve. The prinicipal mechanism of ignition in the test is considered to be the heating of the gas initially in the test chamber by adiabatic compression; the presence of voids in the test materials may also be important.
    Keywords: NONMETALLIC MATERIALS
    Type: Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres; Apr 06, 1987 - Apr 08, 1987; Cambridge
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Ignition of steel alloys by impact of low-velocity iron/inert particles in gaseous oxygen (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The ignition of carbon steel and 316 and 304 stainless steels caused by the impact of low-velocity particles (a standard mixture consisting of 2 g of iron and 3 g of inert materials) in gaseous oxygen was investigated using NASA/White Sands Test Facility for the ignition test, and a subsonic particle impact chamber to accelerate the particles that were injected into flowing oxygen upstream of the target specimen. It was found that the oxygen velocities required to ignite the three alloys were the same as that required to ignite the particle mixture. Ignition occurred at oxygen velocities greater than 45 m/sec at 20 to 24 MPa and was found to be independent of pressure between 2 and 30 MPa. Comparison of the present results and the past results from Wegener (1964) with the Compressed Gas Association (CGA) oxygen velocity limits for safe operations indicates that the CGA limits may be excessively conservative at high pressures and too liberal at low pressures.
    Keywords: METALLIC MATERIALS
    Type: Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres; Apr 06, 1987 - Apr 08, 1987; Cambridge
    Format: text
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    NASA TECHNICAL REPORTS
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