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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Filters, formed by combinations of distributed RC elements with positive-feedback voltage amplifiers, provide transfer functions similar to those the heavier LC filters ordinarily employ. They also provide signal amplification.
Transducer consists of a hybrid thin film and a piezoelectric transistor that acts as a stress-sensitive device with built-in gain. It provides a stress/strain transducer that incorporates a signal amplification stage and sensor in a single package.
System for monitoring of fluidic pressures in cranial cavity uses a miniaturized pressure sensing transducer, combined with suitable amplification means, a meter with scale calibrated in terms of pressures between minus 100 and plus 900 millimeters of water, and a miniaturized chart recorder covering similar range of pressures.
Microwave amplification in high resistivity gallium arsenides
Molecular excitation model for maser amplification of emission lines of interstellar hydroxyl radical
Flux gate magnetometer with toroidal gating coil and solenoidal output coil for signal modulation or amplification
Electrostatic drift-dissipative plasma instability and nocturnal equatorial spread F irregularities, discussing amplification in collision dominated medium
Tunable optical parametric oscillators including Gaussian beams amplification, threshold, tuning techniques, spectral output, etc
Atomic physics of lasers and active materials, noting multiplet spectra of atoms, molecular specroscopy, energy level population distribution and amplification
Parachute opening load amplification due to suspension line elasticity, using two-body spring- mass model
Display systems, fluid amplification techniques, stochastic processes, and thrust vector control systems
Clamped amplifier circuit for horizon scanner enabling amplification and accurate measurement of specified parameters
Pulsars as rotating magnetic neutron stars, examining radio emission via maser amplification
Pulsar radio emission via maser amplification, presenting model based on electrons behavior in intense magnetic field
Three-stage amplifier is used for ECG measurements which require conversion of differential input to single-ended output. Circuit may be useful in biological telemetry for amplification of signals from specimen-implanted sensors.
Electrical data storage tube is assembled from standard vidicon tube using conventional amplification and control circuits. Vidicon storage tube is simple, inexpensive and has an erase and preparation time of less than 5 microseconds.
Fourier analysis was applied to microdensitometer scans of a selected region of one SO65 frame in each of the three black-and-white bands. The approach was unique because a somewhat arbitrary section of the image was used and not limited to available targets as in edge analysis. Comparison of duplicates and calculation of absolute SO65 MTF were done by applying linear systems theory to the spatial spectra of the image scans. It was found that the duplication process was nonlinear and resulted in general amplification of spatial frequency modulation. However, the increase in modulation was offset by a corresponding increase in the granularity of the copies. The amount of increase seemed to be related to the initial granularity, but a direct relationship was not verified. Band-to-band comparison of image quality was achieved in the form of signal-to-noise ratio curves as a function of spatial frequency for each band. From this standpoint the DD band was an order of magnitude better than the other two. These were several factors that restricted the analysis of the Apollo 9 imagery. Among these were the lack of precise sensitometric and optical system data on the high altitude photography. In addition it was determined that there was only one simultaneous pair of high altitude and SO65 frames. Finally, the original SO65 photography was not available for scanning (for obvious reasons), thus eliminating a reference base for granularity and SO65 MTF determination.
This paper presents results of a theoretical and experimental study of shock interference heating which encompassed a variety of basic body shapes and flow conditions. Measurements of pressure and heat transfer were obtained in four wind tunnels at NASA-Langley Research Center. These data cover the Mach number range from 6 to 20, and specific heat ratio range from 1.20 to 1.67. Peak heating measurements up to 17 times ordinary stagnation point rates and pressure peaks up to 8 times freestream pitot pressure were recorded. Numerical results from computer codes developed for each of the six types of interference compare favorably with most of the experimental data. A theoretical parametric study determined the effects of Mach number, specific heat ratio, and impinging shock strength on amplification of pressure and heat transfer. The results of this study show that shock interference is important for hypersonic vehicles such as the Space Shuttle. The problem is aggravated by changes along the flight path of the particular type of interference and the location of regions of peak heat transfer and pressure.