SEARCH · Engineering Papers
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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Electron beam of cathode ray tube with fast phosphor is intensity-modulated by input signal to produce repetitive horizontal trace of luminous intensity proportional to time-varying signal strength. Horizontal trace of cathode ray tube occurs so repetitive portion of signal of interest is encompassed within its length.
Luminous intensity and efficiency parameters for hypersonic reentry of nickel artificial meteors
Space simulator modification to incorporate larger solar simulator, noting beam diameter and luminous intensity uniformity
Pulsars and ancient chinese records of supernova explosions, relating luminous intensities, radio sources and evolution
Light emitting diodes (LEDs) are a promising irradiation source for plant growth in space. Improved semiconductor technology has yielded LED devices fabricated with gallium aluminum arsenide (GaAlAs) chips which have a high efficiency for converting electrical energy to photosynthetically active radiation. Specific GaAlAs LEDs are available that emit radiation with a peak wavelength near the spectral peak of maximum quantum action for photosynthesis. The electrical conversion efficiency of installed systems (μmol s -1 of photosynthetic photons per watt) of high output LEDs can be within 10% of that for high pressure sodium lamps. Output of individual LEDs were found to vary by as much as 55 % from the average of the lot. LED ratings, in mcd (luminous intensity per solid angle), were found to be proportional to total photon output only for devices with the same dispersion angle and spectral peak. Increasing current through the LED increased output but also increased temperature with a consequent decrease in electrical conversion efficiency. A photosynthetic photon flux as high as 900 μmol m -2 s -1 has been produced on surfaces using arrays with LEDs mounted 7.6 mm apart, operating at a current of 50 mA device -1 and at an installed density of approximately 17,200 lamps m -2 of irradiated area. Advantages of LEDs over other electric light sources for use in space systems include long life, minimal mass and volume and being a solid state device.
On the bases of results simultaneous photographic and radio echo observations, the results complex radar and television observations of meteors and also results of laboratory modeling of processes of a luminescence and ionization, correlation between of luminous intensity Ip to linear electronic density q from of velocities and chemical structure are investigated. It is received that by increasing value of velocities of meteors and decrease of nuclear weight of substance of particles, lg Ip/q decreased more than one order.
Mechanism modulates and controls the intensity of luminous radiation in light beams associated with high-intensity heat flux. This modulator incorporates two fluid-cooled, externally grooved, contracting metal cylinders which when rotated about their longitudinal axes present a circular aperture of varying size depending on the degree of rotation.
Effect of temperature, x-rays, light and ultraviolet irradiation on the luminous emission of fungi
Two-dimensional problem of reconstructing true luminance indicatrix from measured smoothed curve
Luminosity function used to estimate invisible planet-like objects in sun neighborhood in relation to main sequence stars
Effect of aerodynamic characteristics of nose bluntness on electromagnetic and luminous efficiency by comparing radar and optical data of two reentry bodies at escape velocities
Statistical analysis of photographic meteor data - Opiks luminous efficiency and supplemented Whipple weighting
Brightness and polarization of zodiacal light at 5300 angstroms derived from observations with photoelectric polarimeter
Validity of Kirchhoff law for apparent local spectral emittance and absorptance and total flux calculations for spacecraft cavities
Velocity dependence of meteor luminous efficiency evaluated, using statistical analysis
Height-luminosity distribution of auroral hydrogen beta emission measured with rocket mounted photometer
Analysis of meteor luminous efficiency based on photographic data, taking into account fragmentation effects
Simulated meteor entry tests in high enthalpy plasma jet to determine meteor ablation and radiation characteristics