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  • 1
    Publication Date: 2013-08-31
    Description: Variations in cavity wall and injection configurations of the gas core reactor were aimed at establishing flow patterns that give a maximum of the nuclear criticality eigenvalue. Correlation with the nuclear effect was made using multigroup diffusion theory normalized by previous benchmark critical experiments. Air was used to simulate the hydrogen propellant in the flow tests, and smoked air, argon, or Freon to simulate the central nuclear fuel gas. Tests were run both in the down-firing and upfiring directions. Results showed that acceptable flow patterns with volume fraction for the simulated nuclear fuel gas and high flow rate ratios of propellant to fuel can be obtained. Using a point injector for the fuel, good flow patterns are obtained by directing the outer gas at high velocity long the cavity wall, using louvered injection schemes. Recirculation patterns were needed to stabilize the heavy central gas when different gases are used.
    Keywords: NUCLEAR ENGINEERING
    Type: ANCR-1118 , NASA-CR-121191
    Format: application/pdf
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  • 2
    Publication Date: 2013-08-31
    Description: Propellant gases emitted by attitude control systems such as SPARCS (Solar Pointing Aerobee Rocket Control System) and possible interference with experiments aboard the payloads are discussed. The optical properties of seven actual and potential gases emitted by propellant systems (CF4, N2H4, NH3, N2, CO2, Ar, and He) are presented. A compilation of absorption coefficients from 1 Angstrom to 50 microns and a summary of fluorescent spectra and efficiencies are provided. Since Freon-14 (CF4) is of primary importance to SPARCS, an experimental search for the fluorescent spectrum of CF4 was performed by exciting the gas with 920 Angstrom UV photons. The result was compared with an electron impact induced spectrum of CF4, and conclusions drawn about the nature of the radiating species. A detailed study of the CF4 flow fields and plume densities for typical SPARCS controlled payloads was made using gas dynamic codes which included the effects of vehicle shading and condensation. The importance of the optical properties of CF4 plumes was investigated and it is concluded that absorption is negligible but fluoresence may be significant in some cases.
    Keywords: THERMODYNAMICS AND COMBUSTION
    Type: NASA-CR-114508
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  • 3
    Publication Date: 2017-07-01
    Description: Microorganism growth supporting or biocidal properties of spacecraft paint coatings
    Keywords: BIOSCIENCES
    Type: NASA-CR-113798
    Format: application/pdf
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  • 4
    Publication Date: 2017-07-01
    Description: Investigating spacecraft coatings for resistance to growth of microorganisms
    Keywords: MATERIALS, NONMETALLIC
    Type: NASA-CR-111524
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  • 5
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Nylon-based membranes of greater dialyzing capacity than Cuprophan have been prepared by solution casting. Good permeability is being achieved by the use of diluents such as dimethylsulfoxide in the casting solution. Modifying resins, primarily epoxies, contribute to higher permeability, good aging stability, and heat-sealing properties. Drying time between film casting and water immersion as well as the temperature and composition of the immersion bath are important factors in membrane performance. Methods for attaching heparin to the film surface have been developed, thus imparting good blood compatibility to the membranes.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2011-08-16
    Description: A critical experiment with spherical symmetry has been conducted on the gas core nuclear reactor concept. The nonspherical perturbations in the experiment were evaluated experimentally and produce corrections to the observed eigenvalue of approximately 1% delta k. The reactor consisted of a low density, central uranium hexafluoride gaseous core, surrounded by an annulus of void or low density hydrocarbon, which in turn was surrounded with a 97-cm-thick heavy water reflector.
    Keywords: NUCLEAR ENGINEERING
    Type: Nuclear Science and Engineering; 47; Jan. 197
    Format: text
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  • 7
    Publication Date: 2011-08-16
    Description: Linear system optimal stochastic control and observation strategies simultaneous determination with quadratic cost by dynamic programming
    Keywords: ELECTRONICS
    Type: ; YAL SOCIETY (
    Format: text
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  • 8
    Publication Date: 2016-03-07
    Description: A device is reported for regulating the pneumatic pressure in a ventilated space suit relative to the pressure imposed on the suit when being worn by a person underwater to simulate space environment for testing and experimentation. A box unit located on the chest area of the suit comprises connections for suit air supply and return lines and carries a regulator valve that stabilizes the air pressure differential between the inside and outside of the suit. The valve and suit pressure is controlled by the suit occupant and the valve includes a mechanism for quickly dumping the suit pressure in case of emergency. Pressure monitoring and relief devices are also included in the box unit.
    Keywords: BIOTECHNOLOGY
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  • 9
    Publication Date: 2013-08-31
    Description: An evaluation of a scale model of a low pressure rocket engine which is used for secondary injection studies was conducted. Specific objectives of the evaluation were to: (1) assess the test conditions required for full scale simulations; (2) recommend fluids to be used for both primary and secondary flows; and (3) recommend possible modifications to be made to the scale model and its test facility to achieve the highest possible degree of simulation. A discussion of the theoretical and empirical scaling laws which must be observed to apply scale model test data to full scale systems is included. A technique by which the side forces due to secondary injection can be analytically estimated is presented.
    Keywords: PROPULSION SYSTEMS
    Type: HREC-8899-2 , LMSC/HREC-D306359 , NASA-CR-124176
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  • 10
    Publication Date: 2011-04-07
    Description: All selected coatings contain nutrients that support microbial growth and survival. Incorporation of microbiocidal agents into coatings more susceptible to attack is recommended for improved inhibition of microorganism growth and for increased protection against deterioration of coatings by microorganisms.
    Keywords: MATERIALS
    Type: MFS-20458
    Format: application/pdf
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