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  • 1
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    A rule-based software test data generator (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Rule-based software test data generation is proposed as an alternative to either path/predicate analysis or random data generation. A prototype rule-based test data generator for Ada programs is constructed and compared to a random test data generator. Four Ada procedures are used in the comparison. Approximately 2000 rule-based test cases and 100,000 randomly generated test cases are automatically generated and executed. The success of the two methods is compared using standard coverage metrics. Simple statistical tests showing that even the primitive rule-based test data generation prototype is significantly better than random data generation are performed. This result demonstrates that rule-based test data generation is feasible and shows great promise in assisting test engineers, especially when the rule base is developed further.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: IEEE Transactions on Knowledge and Data Engineering (ISSN 1041-4347); 3; 108-117
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  • 2
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    Sonic boom (human response and atmospheric effects) outdoor-to-indoor response to minimized sonic booms (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The preferred descriptor to define the spectral content of sonic booms is the Sound Exposure Spectrum Level, LE(f). This descriptor represents the spectral content of the basic noise descriptors used for describing any single event--the Sound Exposure Level, LE. The latter is equal to ten times the logarithms, to the base ten, of the integral, over the duration of the event, of the square of the instantaneous acoustic pressure, divided by the square of the reference pressure, 20 micro-Pa. When applied to the evaluation of community response to sonic booms, it is customary to use the so-called C-Weighted Sound Exposure Level, LCE, for which the frequency content of the instantaneous acoustic pressure is modified by the C-Weighting curve.
    Keywords: ACOUSTICS
    Type: NASA. Langley Research Center, First Annual High-Speed Research Workshop, Part 3; p 1345-1363
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  • 3
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    Fiber-optic push-pull sensor systems (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Fiber-optic push-pull sensors are those which exploit the intrinsically differential nature of an interferometer with concommitant benefits in common-mode rejection of undesired effects. Several fiber-optic accelerometer and hydrophone designs are described. Additionally, the recent development at the Naval Postgraduate School of a passive low-cost interferometric signal demodulator permits the development of economical fiber-optic sensor systems.
    Keywords: OPTICS
    Type: NASA, Washington, Technology 2001: The Second National Technology Transfer Conference and Exposition, Volume 2; p 415-422
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  • 4
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    Alternative catalysts for low-temperature CO-oxidation (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: MnO sub x, Ag/MnO sub x, Cu/MnO sub x, Pt/MnO sub x, Ru/MnO sub x, Au/CeO sub x, and Au/Fe2O3 were synthesized and tested for CO oxidation activity in low concentrations of stoichiometric CO and O2 at 30 to 75 C. Catalytic activity was measured for periods as long as 18000 minutes. At 75 deg Au/MnO sub x is most active sustaining nearly 100 percent CO conversion for 10000 minutes. It also retains high activity at 50 and 30 C with negligible decay in activity. A direct comparison between an unpretreated 10 percent Au/MnO sub x catalyst and an optimized 19.5 percent Pt/SnO sub 2 (pretreated) catalyst shows that the Au/MnO sub x catalyst exhibits much higher catalytic activity and far superior decay characteristics. Other catalysts including Au/CeO sub x and Au/Fe2O3 also perform well. The Cu/MnO sub x exhibits a high initial activity which decays rapidly. After the decay period the activity remains very stable making Cu/MnO sub x a potential candidate for long-term applications such as CO2 lasers in space.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: Low-Temperature CO-Oxidation Catalysts for Long-Life CO2 Lasers; p 123-137
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  • 5
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    Pt/SnO2-based CO-oxidation catalysts for long-life closed-cycle CO2 lasers (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Noble-metal/tin-oxide based catalysts such as Pt/SnO2 have been shown to be good catalysts for the efficient oxidation of CO at or near room temperature. These catalysts require a reductive pretreatment and traces of hydrogen or water to exhibit their full activity. Addition of Palladium enhances the activity of these catalysts with about 15 to 20 percent Pt, 4 percent Pd, and the balance SnO2 being an optimum composition. Unfortunately, these catalysts presently exhibit significant decay due in part to CO2 retention, probably as a bicarbonate. Research on minimizing the decay in activity of these catalysts is currently in progress. A proposed mechanism of CO oxidation on Pt/SnO2-based catalysts has been developed and is discussed.
    Keywords: LASERS AND MASERS
    Type: Low-Temperature CO-Oxidation Catalysts for Long-Life CO2 Lasers; p 41-53
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  • 6
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    Molecular origin of Io's fast sodium (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Neutral sodium emissions encircling Jupiter exhibit an intricate and variable structure that is well matched by a simple loss process from Io's atmosphere. These observations imply that fast neutral sodium is created locally in the Io plasma torus, both near Io and as much as 8 hours downstream. Sodium-bearing molecules may be present in Io's upper atmosphere, where thay are ionized by the plasma torus and swept downstream. The molecular ions dissociate and dissociatively recombine on a short time scale, releasing neutral fragments into escape trajectories from Jupiter. This theory explains a diverse set of sodium observations, and it implies that molecular reactions (particularly electron impact ionization and dissociation) are important at the top of Io's atmosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 253; 1394-139
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  • 7
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    Improvement of modal scaling factors using mass additive technique (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A general investigation into the improvement of modal scaling factors of an experimental modal model using additive technique is discussed. Data base required by the proposed method consists of an experimental modal model (a set of complex eigenvalues and eigenvectors) of the original structure and a corresponding set of complex eigenvalues of the mass-added structure. Three analytical methods,i.e., first order and second order perturbation methods, and local eigenvalue modification technique, are proposed to predict the improved modal scaling factors. Difficulties encountered in scaling closely spaced modes are discussed. Methods to compute the necessary rotational modal vectors at the mass additive points are also proposed to increase the accuracy of the analytical prediction.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-Marshall Space Flight Center, The 58th Shock and Vibration Symposium, Volume 1; p 193-202
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  • 8
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    A new method to real-normalize measured complex modes (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A time domain subspace iteration technique is presented to compute a set of normal modes from the measured complex modes. By using the proposed method, a large number of physical coordinates are reduced to a smaller number of model or principal coordinates. Subspace free decay time responses are computed using properly scaled complex modal vectors. Companion matrix for the general case of nonproportional damping is then derived in the selected vector subspace. Subspace normal modes are obtained through eigenvalue solution of the (M sub N) sup -1 (K sub N) matrix and transformed back to the physical coordinates to get a set of normal modes. A numerical example is presented to demonstrate the outlined theory.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-Marshall Space Flight Center, The 58th Shock and Vibration Symposium, Volume 1; p 169-180
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  • 9
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    Automated procedure execution for space vehicle autonomous control (1990)
    In:  CASI
    Details
    Publication Date: 2019-04-02
    Description: Increased operational autonomy and reduced operating costs have become critical design objectives in next-generation NASA and DoD space programs. The objective is to develop a semi-automated system for intelligent spacecraft operations support. The Spacecraft Operations and Anomaly Resolution System (SOARS) is presented as a standardized, model-based architecture for performing High-Level Tasking, Status Monitoring and automated Procedure Execution Control for a variety of spacecraft. The particular focus is on the Procedure Execution Control module. A hierarchical procedure network is proposed as the fundamental means for specifying and representing arbitrary operational procedures. A separate procedure interpreter controls automatic execution of the procedure, taking into account the current status of the spacecraft as maintained in an object-oriented spacecraft model.
    Keywords: CYBERNETICS
    Type: NASA, Goddard Space Flight Center, The 1990 Goddard Conference on Space Applications of Artificial Intelligence; p 239-250
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  • 10
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    Fabrication of 15-cm-dia. Carbon-Carbon Grids (1993)
    In:  Other Sources
    Details
    Publication Date: 2018-06-08
    Description: Carbon-carbon composite ion gird blanks measuring 20cm on a side and 0.5-1.0mm in thickness were fabricated from laminated plies of unidirectional carbon-carbon tape.
    Format: text
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