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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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In the observation slewing of long base-line interferometers formed by multiple free-flying spacecraft in formation, it is required to rotate the entire formation about a given axis, and to synchronize individual spacecraft rotation with formation rotation.
A new technique, called multiple endmember spectral mixture analysis (MESM) was developed and tested in the Santa Monica Mountains, using Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data acqired in the fall of 1994 to map California chaparral.
Sonic booms are often modeled using Burgers equations accounting for dominant propagation effects. Scattering effects of turbulence, however, have not been incorporated into such equations, although these effects are ubiquitous in measured sonic booms. This paper formulates the mean scattering effects, including backscattering, using multiple scattering theory and ensemble averaging. It obtains an acousto-turbulence interaction energy representing the interaction of an acoustic wave field with a turbulence field. The interaction energy gives rise to a scattering wavenumber, a complex-valued correction to the free-space wavenumber. The scattering wavenumber leads to a dispersion and attenuation of the mean waveform due to backscattering, and can be obtained from a derived exact solution. An existing Burgers equation is extended to include the scattering effects of turbulence as an additional linear term. Numerical simulations of an N-wave and a low boom show that the mean scattering effects lead to shock thickening in the mean waveforms as well as reduce the peak amplitudes and total energy contents. The energy reduction is less severe in the low boom than in the N-wave and is dependent on the variance, correlation length, and thickness of the turbulence field.
Guidance policies for multiple-impulse correction of spacecraft trajectory
Fast, accurate, multipressure measuring system, which employs a multiple port pressure scanning valve that connects a pressure transducer to many pressures, is described.
Pressure distribution on base and afterbody of missile configuration with and without jet flow using single and multiple nozzles
An experimental investigation has been made of some lunar-landing characteristics of a 1/6-scale dynamic model of a landing module having multiple-leg landing-gear systems. Symmetric four-point and five-point systems were investigated. The landing-gear legs were inverted tripod arrangements having a telescoping main strut which incorporated a yielding-metal strap for energy dissipation, hinged V-struts, and circular pads. The landing tests were made by launching a free model onto an impenetrable hard surface (concrete) and onto a powdered-pumice overlay of various depths. Landing motion and acceleration data were obtained for a range of touchdown speeds, touchdown attitudes, and landing-surface conditions. Maximum normal acceleration experienced at the module center of gravity during landings on hard surface or pumice was 2g (full-scale lunar value in terms of earth's gravity) over a wide range of touchdown conditions. acceleration experienced was 12 1/2 radians/sec(exp 2) and maximum longitudinal acceleration was 1 3/4g. The module was very stable with all gear configurations during landings on hard surface (coefficient of friction, micron = 0.4) at all conditions tested. Some overturn instability occurred during landings on powdered pumice (micron = 0.7 to 1.0) depending upon flight path, pitch and yaw attitude, depth of pumice, surface topography, and landing-gear configuration. The effect on stability of roll attitude for the limited amount of roll-attitude landing data obtained was insignificant. Compared with the four-point landing gear, the five-point system with equal maximum gear radius increased landing stability slightly and improved the static stability for subsequent lunar launch. A considerable increase in landing stability in the direction of motion was obtained with an asymmetric four-point gear having two pads offset to increase gear radius by 33 percent in the direction of horizontal flight.
Calculation of integral multiplicity of mu-meson production in atmosphere for observation under different thicknesses of absorber
Use of multiple dees in frequency modulated cyclotron
Neutron self-shielding factors for multiple-body concentric cylinder configurations
Square-loop cores with multiple windings used in single transformer package for application in self-oscillating inverters
Magnetic-coupled multivibrators containing two or more square-loop cores with multiple windings in a single transformer package, provide indirect frequency control and improved operational characteristics. This multivibrator can be used for power oscillators, nonlinear magnetic circuitry and telemetry circuits.
Mechanical device simultaneously stirs multiple test tubes under controlled laboratory conditions. The invention provides a variable stirring rate, minimal amount of contamination of tube contents, unattended and simple operation, and easy maintenance and cleaning.
Multiple compartment test chamber exposes several material specimens to various environmental conditions for prolonged periods. The specimens are individually mounted in chamber compartments, rotated to various positions, and measured through optical windows to determine progressive changes in the material properties.
Nonlinear phenomena in single and multiple electron beams of infinite radius in nonplanar field
Three-stage multiple-reentry turbine for auxiliary power application - design and testing
Multiple access satellite communication systems
Multiple or stacked detectors and single fixed detector - improved X-ray vidicon, operation of flat plate Geiger counter, electronic readout system, and Seeman-Bohling focusing camera