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  • 11
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    The role of large particles in the formation of the radio echo (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The contribution to the total reflectivity of separate parts of a particle spectrum described by a gamma distribution is estimated. It is shown that the largest individual particles, whose percent concentration is 0.1 - 1, originate approximately 60 - 70% of the total reflectivity of the spectrum. Explanations are given of a number of effects which confirm the dominant role of large particles in the formation of the echo.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radar Meteorology (NASA-TT-F-14797); p 7-13
    Format: text
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  • 12
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    Refinement of the basic radar equation for clouds and precipitation (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A derivation of the basic radar equation for clouds and precipitation is given that takes into account the antenna radiation pattern. The reasons for the differences in the equations used by various authors are demonstrated. More rigorous forms for writing down the basic equation are given.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Radar Meteorology (NASA-TT-F-14797); p 1-6
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  • 13
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    Annealing characteristics of amorphous silicon alloy solar cells irradiated with 1.00 MeV protons (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Amorphous Si:H and amorphous Si sub x, Ge sub (1-x):H solar cells were irradiated with 1.00 MeV proton fluences in the range of 1.00E14 to 1.25E15 cm (exp -2). Annealing of the short circuit current density was studied at 0, 22, 50, 100, and 150 C. Annealing times ranged from an hour to several days. The measurements confirmed that annealing occurs at 0 C and the initial characteristics of the cells are restored by annealing at 200 C. The rate of annealing does not appear to follow a simple nth order reaction rate model. Calculations of the short-circuit current density using quantum efficiency measurements and the standard AM1.5 global spectrum compare favorably with measured values. It is proposed that the degradation in J sub sc with irradiation is due to carrier recombination through the fraction of D (o) states bounded by the quasi-Fermi energies. The time dependence of the rate of annealing of J sub sc does appear to be consistent with the interpretation that there is a thermally activated dispersive transport mechanism which leads to the passivation of the irradiation induced defects.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA. Lewis Research Center, Space Photovoltaic Research and Technology Conference; 9 p
    Format: application/pdf
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  • 14
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    Interpretation of multispectral and infrared thermal surveys of the Suez Canal Zone, Egypt (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Remote sensing airborne surveys were conducted, as part of the plan of rehabilitation, of the Suez Canal Zone using I2S multispectral camera and Bendix LN-3 infrared passive scanner. The multispectral camera gives four separate photographs for the same scene in the blue, green, red, and near infrared bands. The scanner was operated in the microwave bands of 8 to 14 microns and the thermal surveying was carried out both at night and in the day time. The surveys, coupled with intensive ground investigations, were utilized in the construction of new geological, structural lineation and drainage maps for the Suez Canal Zone on a scale of approximately 1:20,000, which are superior to the maps made by normal aerial photography. A considerable number of anomalies belonging to various types were revealed through the interpretation of the executed multispectral and infrared thermal surveys.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: ERIM Proc. of the 11th Intern. Symp. on Remote Sensing of Environment, Vol. 2; p 1533-1542
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  • 15
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    Corrections for line-of-sight velocities on account of the daily rotation and annual revolution of the earth during solar observations (1966)
    In:  CASI
    Details
    Publication Date: 2019-05-30
    Description: Line of sight velocity corrections for daily rotation and annual revolution of earth during solar observations
    Keywords: PHYSICS, GENERAL
    Type: NASA-CR-77702 , ST-SPHA-10461
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  • 16
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    Effects of leading-edge flap oscillation on unsteady delta wing flow and rock control (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The isolated and interdisciplinary problems of unsteady fluid dynamics and rigid-body dynamics and control of delta wings with and without leading-edge flap oscillation are considered. For the fluid dynamics problem, the unsteady, compressible, thin-layer Navier-Stokes (NS) equations, which are written relative to a moving frame of reference, are solved along with the unsteady, linearized, Navier-displacement (ND) equations. The NS equations are solved for the flowfield using an implicit finite-volume scheme. The ND equations are solved for the grid deformation, if the leading-edge flaps oscillate, using an ADI scheme. For the dynamics and control problem, the Euler equation of rigid-body rolling motion for a wing and its flaps are solved interactively with the fluid dynamics equations for the wing-rock motion and subsequently for its control. A four-stage Runge-Kutta scheme is used to explicitly integrate the dynamics equation.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 91-1796
    Format: text
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  • 17
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    Prediction and control of slender-wing rock (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The unsteady Euler equations and the Euler equations of rigid-body dynamics, both written in the moving frame of reference, are sequentially solved to simulate the limit-cycle rock motion of slender delta wings. The governing equations of the fluid flow and the dynamics of the present multidisciplinary problem are solved using an implicit, approximately-factored, central-difference-like, finite-volume scheme and a four-stage Runge-Kutta scheme, respectively. For the control of wing-rock motion, leading-edge flaps are forced to oscillate anti-symmetrically at prescribed frequency and amplitude, which are tuned in order to suppress the rock motion. Since the computational grid deforms due to the leading-edge flaps motion, the grid is dynamically deformed using the Navier-displacement equations. Computational applications cover locally-conical and three-dimensional solutions for the wing-rock simulation and its control.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: In: ICAS, Congress, 18th, Beijing, China, Sept. 20-25, 1992, Proceedings. Vol. 2 (A93-14151 03-01); p. 1430-1441.
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  • 18
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    Three-dimensional simulation of slender delta wing rock and divergence (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Computational simulation of three-dimensional flows around a delta wing undergoing rock and roll-divergence motions is presented. The problem is a multidisciplinary one where fluid-dynamics equations and rigid-body-dynamics equations are sequentially solved. For the fluid-dynamics part, the unsteady Euler equations, which are written relative to a moving frame of reference, are solved using an implicit, approximately-factored, central-difference, finite-volume scheme. For the rigid-body dynamics part, the Euler equation of rigid-body rolling motion is solved using a four-stage Runge-Kutta scheme. Since the applications do not include deforming wings or relative-rigid-body motions, the computational-fluid-dynamics grid, which is fixed in the moving frame of reference, does not need to be updated once it is generated.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 92-0280
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  • 19
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    Unsteady vortex-dominated flow around wings with oscillating leading-edge flaps (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Unsteady vortex-dominated flow around delta wings with oscillating leading-edge flaps represents an important classs of problems for supermaneuverability and flow control of advanced aircraft. The problem is solved using time accurate integration of the unsteady, compressible, thin-layer Navier-Stokes equations in conjunction with the unsteady, linearized, Navier-displacement equations. Starting with an initial configuration of the wing and its flaps, the Navier-Stokes equations are solved on an initial structured grid for the steady flow. The forced oscillation of the flaps is then applied, and the problem is solved accurately in time. The Navier-displacement equations are solved for the grid deformation and the Navier-Stokes equations are solved for the flowfield. Symmetric and anti-symmetric flaps oscillations are presented to study the effect of the flaps oscillation on the leading-edge vortical flow.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 91-0435
    Format: text
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  • 20
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    Geological and groundwater potential studies of El Ismailiya master plan study area (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: There are no author-identified significant results in this report.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: E78-10170 , NASA-CR-157288
    Format: application/pdf
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