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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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Mechanical shield of high melting point material protects 6061-T6 aluminum welded with high frequency ac tungsten arc equipment. It is held in place around the weld bead area and eliminates heat check cracks.
Prototype precision bolometer calibration bridge is manually balanced device for indicating dc bias and balance with either dc or ac power. An external galvanometer is used with the bridge for null indication, and the circuitry monitors voltage and current simultaneously without adapters in testing 100 and 200 ohm thin film bolometers.
Uncontrolled high frequency current causes cracking in the heat-affected zone of aluminum alloy 6061 weldments during tungsten inert gas ac welding. Cracking developed when an improperly adjusted superimposed high frequency current was agitating the semimolten metal in the areas of grain boundary.
Automated statistical and worst case computer program has been designed to perform dc and ac steady circuit analyses. The program determines the worst case circuit performance by solving circuit equations.
Numerical analysis of winding power loss of rotating ac generators in controlled atmospheres
AC induced voltages in Nb and Nb-Zr superconducting wires, measuring I-V curves and energy loss per cycle
Detrimental influence of structural oscillations excited by ACS on attitude control and pointing performance of large satellite antenna
Self contained atomic hydrogen maser frequency standard design and development, discussing AC power requirement, control circuitry, operating parameters and stability
AC motor design for operation in He in cryogenic to room temperature range, noting performance parameters and design considerations
N and p channel MOSFET operation at 4.2 K noting noise, AC gain, power dissipation and deterioration under thermal cycling from room temperature
Magnetic coupling between input and power handling circuits isolates high voltage. A feedback regulator samples the ion source bias current and provides deviation signals to a magnetic amplifier pulse modulator. The pulse modulator controls the dc to ac power inverter which in turn, controls the emission current.
Generation of intense sonic and ultrasonic power in the weld zone, close to the puddle, reduces the porosity and refinement of the grain. The ac induction brazing power supply is modified with long cables for deliberate addition of resistance to that circuit. The concept is extensible to the molding of metals and plastics.
Transient stability of AC generator analyzed by Liapunov direct method, considering effects of flux decay, speed governor and voltage regulator
AC technique using lock-in power amplifier SNR for measuring galvanomagnetic and Shubnikov-de Haas effects, noting error reduction
Absorption spectrum of diatomic oxygen excited by AC silent discharge photographed with vacuum spectrograph, associating lines with Schumann- Runge band
Modularized static AC and DC inverters and converters for aerospace electrical power conditioning systems, discussing circuit functions and performance tests
Establishing an arc between water-cooled tungsten-tipped electrodes, maintaining the arc along the centerline of a central jet of argon gas, and surrounding the argon jet with a coaxial sheath of nitrogen stabilizes operation of a low-frequency ac electric arc.