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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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TWM /Traveling Wave Master/ comb structure serves as a highly stable microwave delay line for determining the short-term stability of the hydrogen maser frequency standards used in the deep space network. Cryogenic cooling is used to minimize signal attenuation and thermal noise.
Effects of ionosphere on 400 Mc radar signals sent vertically downward from satellite - time delay and virtual height, attenuation factor, and Faraday rotation
A theoretical analysis of the propagation characteristics of a finite amplitude pressure wave is presented. The analysis attempts to study the contribution of entropy-producing regions to the mechanism of aerodynamic noise generation. It results in a nonlinear convective wave equation in terms of entropy and a thermodynamic 'J' function. A direct analogy between the derived governing equation and those used in classical literature is obtained. An idealization of the processes considered permits the uncoupling of the equations of motion with a consequent construction of an acoustic analogy treating shock wave emission of finite amplitude acoustic waves. An engineering approach is reflected in the concept of an extended plug nozzle whose function is to facilitate aerodynamic noise attenuation by modifying the entropy-producing regions.
Neutron and gamma attenuation cross sections in concretes with additives for shielding material
Nuclear magnetic resonance measurement of impurities in magnetic garnets - ferromagnetic relaxation in metals and in magnetic oxides - ultrasonic attenuation in magnetic oxides
The lunar module (LM) landing phase is one of the most critical phases of the entire Apollo mission. Landing impact is of critical concern because at no other time during the LM mission is there less opportunity for vehicle control. To assure a successful landing, the alightment system must not only provide required shock attenuation for protection of crew and structure, but must also assure stability against overturning after touchdown. The paper discusses important design features of the alightment system, such as geometric arrangement, energy absorber characteristics, and deployment mechanisms. Performance characteristics of the vehicle at touchdown, as found analytically, are presented. Model and full-size testing of the landing system is briefly discussed.
Method of attenuating liquid motion in propellant tanks during vehicle acceleration and orbital coast of flight
Nonlinear attenuation or gain characteristics of Doppler-broadened atomic resonance involving levels with small splittings, noting mode coupling of gas laser
Mechanical impact attenuation system for Apollo spacecraft provides stable land landing platform, noting deployed heat shields, extended legs, pneumatic bags, etc
Attenuation and dispersion of sound in nearly collisionless gases as function of sound-to- particle path ratio
Mechanical impact attenuation system for Apollo spacecraft provides stable land landing platform, noting deployed heat shields, extended legs, pneumatic bags, etc
Attenuation cross section at Lyman alpha for Xe deviation from Beer law indicating diatomic Xe molecule formation
Active vibration isolator simultaneously isolates a flexible structure or payload from disturbances, attenuates the response of a flexible structure to transient disturbances, and maintains the equilibrium position of the payload within predetermined limits over a wide range of steady loads and accelerators.
Comparison is made of the power consumed and the acoustic amplification realized when a dc bias field is placed across a piezoelectric semiconductor and adjusted to amplify a microwave acoustic signal to the point where the forward gain is just equal to the reverse attenuation. This represents the maximum possible gain condition.
Study of the shock and vibration response of a multistage structure employed analytically, lumped-mass, continuous-beam, multimode, and matrix-iteration methods. The study was made on the load paths, transmissibility, and attenuation properties along a longitudinal axis of a long, slender structure with increasing degree of complexity.
Measurements of electrical conductivity, ultrasonic surface wave attenuation, and internal friction loss were made on aluminum alloys 7079-T6, 2219-T31, and 2219-T81 as a function of the onset of stress corrosion.
Photoelectric emission measurements of excited electrons attenuation length in metal films as function of film thickness
Artificial dielectric H-guides, and comparison of attenuation coefficients of H-guides with standard waveguides