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  • SPACECRAFT PROPULSION AND POWER  (2)
  • dormancy  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Seed coat structure and dormancy (1992)
    Springer
    Plant growth regulation 11 (1992), S. 201-209 
    Details
    ISSN: 1573-5087
    Keywords: Seed coat structure ; dormancy ; permeability ; Dichrostachys cinerea ; natural dormancy-breaking factors ; inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An understanding of dormancy mechanisms is of ecological and economic importance. Identification of the level at which dormancy is imposed appears to be species specific. The variation brought about by this therefore requires that developmental studies be included in seed coat dormancy experiments. In most cases, a site of permeability can be identified during the developmental process, and this information can be utilized later to remove dormancy. Under natural conditions, the removal of seed coat dormancy requires the interaction of a number of ecological and physiological dormancy-breaking cues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024559
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The role of natural agents in the removal of coat-imposed dormancy in Dichrostachys cinerea (L.) Wight et Arn. seeds (1994)
    Springer
    Plant growth regulation 14 (1994), S. 51-59 
    Details
    ISSN: 1573-5087
    Keywords: bush encroachment ; Dichrostachys cinerea ; dormancy ; germination ; impermeability ; natural factors ; seed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstracts Dichrostachys cinerea seeds are impermeable to water and do not germinate readily. The plant, however, contributes to a bush encroachment problem, minimising visibility in wildlife reserves and reducing the area available for grazing. Natural dormancy-breaking conditions must therefore exist, promoting the germinability of these normally dormant seeds. Diurnal temperature fluctuations (50°C/15°C), especially when combined with moisture were found to break dormancy. High temperatures, such as those generated by fire, destroyed seeds. Seeds ingested by herbivorous browsers such as nyala, became permeable. Seed burial for 48 weeks, was a more effective treatment than storage in promoting permeability. Distribution of D. cinerea will therefore be restricted to areas in which these conditions or factors occur. Seeds germinated optimally at 30δC in the laboratory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024141
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    Paper (German National Licenses)
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  • 3
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    Unknown
    Measurements of reactive gaseous rocket injector admittances (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The paper describes the results of an experimental study of the quantitative determination of the capabilities of the combustion processes associated with coaxial gaseous propellant rocket injectors to drive combustor pressure oscillations. The data, obtained by employing the modified impedance tube technique with compressed air as the oxidizer and acetylene gas as the fuel, describe the frequency dependence of the admittance of the combined injector-combustion process. The measured data are compared with the predictions of the Feiler and Heidmann analytical model utilizing different values for the characteristic combustion time tau sub b. The values of tau sub b which result in a best fit between the measured and predicted data are indicated for different equivalence ratios. It is shown that for the coaxial injector investigated in this study the tau sub b varies between 0.7 and 1.2 msec for equivalence ratios in the range of 0.57 to 1.31. In addition, the experimental data indicate that the tested injector system could drive combustion instabilities over a frequency range that is in qualitative agreement with the predictions of the Feiler and Heidmann model.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Combustion Science and Technology; 20; 5-6,; 1979
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Measurements of reactive gaseous rocket injector response factors (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The results presented represent the first successful attempt at the measurement of the driving capabilities of coaxial gaseous propellant rocket injectors. The required data have been obtained by employing the modified impedance tube technique with compressed air as the oxidizer and acetylene gas as the fuel. The data describe the frequency dependence of the injector admittances, from which the frequency dependence of the injection response factors can be calculated. The measured injector admittances have been compared with the predictions of the Feiler and Heidmann (1967) analytical model assuming different values for the characteristic combustion time. The values of combustion time which result in a best fit between the measured and predicted data are indicated for different equivalence ratios. It is shown that for the coaxial injector system investigated in this study the characteristic combustion times vary between .7 and 1.2 msec for equivalence ratios in the range of .57 to 1.31. The experimental data clearly show that the tested injector system could indeed drive combustion instabilities over a frequency range that is in qualitative agreement with the predictions of the Feiler and Heidmann model.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Spring Technical Meeting; Mar 28, 1977 - Mar 30, 1977; Cleveland, OH
    Format: text
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    NASA TECHNICAL REPORTS
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