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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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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Rapid analysis of electric propulsion missions

Computer program has been designed to handle computations for low thrust missions rapidly and with acceptable accuracy. Program defines performance and system requirements of electrically-propelled unmanned planet-orbiter and flyby missions. The program is written in FORTRAN 4 for use on an IBM 360 or CDC 6600 computer.

Mascy, A. C.↗
NASA NTRS1971

Some characteristics of turbulent boundary layers in rapidly accelerated flows

An analysis of time-mean-turbulent boundary layer velocity profiles measured in a rapidly accelerating flow suggests that the outer region of the velocity profiles consists of essentially inviscid, rotational flow. The extent of this inviscid outer region was observed in some cases to exceed 90 percent of what is ordinarily thought of as the turbulent boundary layer thickness. On the other hand, the inner frictional region of these velocity profiles appears to have turbulent characteristics similar to those of more conventional turbulent boundary layers. Hence, the outer edge boundary condition for this inner region is more properly the external rotational flow region than the free stream.

Brinich, P. F.↗
NASA NTRS1973

Rapid detection of bacteria in foods and biological fluids

Simple and inexpensive apparatus, called "redox monitoring cell," rapidly detects presence of bacteria. Bacteria is detected by measuring drop in oxygen content in test solution. Apparatus consists of vial with two specially designed electrodes connected to sensitive voltmeter.

Fealey, R. D.↗
NASA NTRS1972

Procedure for rapid determination of nickel, cobalt, and chromium in airborne particulate samples

A rapid, selective procedure for the determination of 1 to 20 micrograms of nickel, chromium, and cobalt in airborne particulates is described. The method utilizes the combined techniques of low temperature ashing and atomic absorption spectroscopy. The airborne particulates are collected on analytical filter paper. The filter papers are ashed, and the residues are dissolved in hydrochloric acid. Nickel, chromium, and cobalt are determined directly with good precision and accuracy by means of atomic absorption. The effects of flame type, burner height, slit width, and lamp current on the atomic absorption measurements are reported.

Davis, W. F.↗
NASA NTRS1973

Studies for determining rapid thrust response requirements and techniques for use in a long range transport aircraft

Propulsion systems proposed for the next generation of long-range transport aircraft will utilize advanced technology to reduce the noise to levels that will be inoffensive to the community. Additional reductions can be realized by adopting steeper glide slopes during the landing approach. The aircraft dynamic characteristics and methods of obtaining rapid engine response during the go-around maneuver from an aborted landing approach are identified and discussed. The study concludes that the present levels of flight safety will not be compromised by the steeper approach.

Newirth, D. M.↗
NASA NTRS1973

Satellite observations during the rapid intensification of hurricane Camille

Medium resolution infrared radiometer observations at the 6.7 micrometer and the 11 micrometer regions by satellite during the maximum intensification phase of hurricane Camille show increasing black body temperatures near the center. This is attributed to increased upward vertical motion in the interior of the cyclone, which is an indication of rapid intensification.

Shenk, W. E.↗
NASA NTRS1973

Rapid gas-phase reactions - The reaction of ammonia and the methylamines with boron trifluoride. III - Pressure dependence of rate constant.

A steady-state flow apparatus, shown earlier to be suitable for the study of rapid gas reactions, has been used to determine the pressure dependence of the relative quasi-bimolecular rate constants for the reactant pairs ammonia (AM)-trimethylamine (TMA) and dimethylamine (DMA)-trimethylamine in reaction with boron trifluoride. The pressure dependence of the former was determined in the range 0.03-75 torr and that of the latter in the range 0.02-720 torr.

Glicker, S.↗
NASA NTRS1973

Nonlinear analysis of phased-locked loops with rapidly varying phase

The performance of command and telemetry systems, useful in deep-space communications, is frequently affected by the radio-frequency phase error which is introduced at the point of reception by means of the carrier tracking loop. In low data rate communications, this phase error may vary rapidly over the duration of the signaling interval. In this paper such phase variation is characterized by a sinusoidal input phase, K sin (omega sub o t+, pi/6), which models a typical phase variation in communication over turbulent media. Conditions for synchronization stability and the acquisition behavior are examined by detailed computer study of the phase-plane trajectories for the second and third-order loops with perfect integrator. It is demonstrated that for the phase variation considered the third-order loop has no real advantage over the second-order loop. Finally, it is shown that nonzero initial conditions may result in large steady-state phase error.

Chen, C.↗