Effects of propagation parallel to the magnetic field on the Type 1 electrojet irregularity instability.
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Lee, K.↗
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Results for “parallelization”
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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Analysis of starting circuits for a class of hard oscillators - Two-transistor saturable-core parallel inverters.
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Lee, F. C. Y.↗
Force sharing in high-power parallel servo-actuators
The various existing force sharing schemes were examined by conducting a literature survey. A list of potentially applicable concepts was compiled from this survey, and a brief analysis was then made of each concept, which resulted in two competing schemes being selected for in-depth evaluation. A functional design of the equalization logic for the two schemes was undertaken and specific space shuttle application was chosen for experimental evaluation. The application was scaled down so that existing hardware could be utilized. Next, an analog computer study was conducted to evaluate the more important characteristics of the two competing force sharing schemes. On the basis of the computers study, a final configuration was selected. A load simulator was then designed to evaluate this configuration on actual hardware.
Neal, T. P.↗
Analysis and modeling of a family of two-transistor parallel inverters
A family of five static dc-to-square-wave inverters, each employing a square-loop magnetic core in conjunction with two switching transistors, is analyzed using piecewise-linear models for the nonlinear characteristics of the transistors, diodes, and saturable-core devices. Four of the inverters are analyzed in detail for the first time. These analyses show that, by proper choice of a frame of reference, each of the five quite differently appearing inverter circuits can be described by a common equivalent circuit. This equivalent circuit consists of a five-segment nonlinear resistor, a nonlinear saturable reactor, and a linear capacitor. Thus, by proper interpretation and identification of the parameters in the different circuits, the results of a detailed solution for one of the inverter circuits provide similar information and insight into the local and global behavior of each inverter in the family.
Lee, F. C. Y.↗
Lunar electromagnetic scattering. II - Magnetic fields and transfer functions for parallel propagation
Magnetic field and transfer function amplitudes, resulting from a transverse electromagnetic wave in the interplanetary medium scattering from the moon and its diamagnetic cavity, are presented. Calculations are made using an asymmetric scattering theory for a spherical two-layer model of the lunar electrical conductivity profile and a nonconducting cylindrical model of the downstream lunar plasma void. Both the field and transfer function magnitudes are calculated as functions of position on the surface of the moon for frequencies relevant to the observations of the lunar surface and orbiting magnetometers. The amplitudes of the magnetic field components on the cavity boundary are also computed as functions of frequency and distance downstream from the lunar limb. Comparisons of the results are made with those of (1) spherically symmetric descriptions of lunar electromagnetic scattering, (2) the quasi-static approximation to asymmetric scattering theory, and (3) observations of the scattering phenomenon by lunar surface and orbiting magnetometers.
Schubert, G.↗
The parallel diffusion coefficient for cosmic rays in a turbulent magnetic field
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Klimas, A.↗
Voltage-spike analysis for a free-running parallel inverter
Unwanted and sometimes damaging high-amplitude voltage spikes occur during each half cycle in many transistor saturable-core inverters at the moment when the core saturates and the transistors switch. The analysis shows that spikes are an intrinsic characteristic of certain types of inverters even with negligible leakage inductance and purely resistive load. The small but unavoidable after-saturation inductance of the saturable-core transformer plays an essential role in creating these undesired thigh-voltage spikes. State-plane analysis provides insight into the complex interaction between core and transistors, and shows the circuit parameters upon which the magnitude of these spikes depends.
Lee, F. C. Y.↗
Serial-to-parallel color-TV converter
Solid analog-to-digital converter eliminates flicker and problems with time base stability and gain variation in sequential color TV cameras. Device includes 3-bit delta modulator; two-field memory; timing, switching, and sync network; and three 3-bit delta demodulators
Doak, T. W.↗
High subsonic flow tests of a parallel pipe followed by a large area ratio diffuser
Experiments were performed on a pilot model duct system in order to explore its aerodynamic characteristics. The model was scaled from a design projected for the high speed operation mode of the Aircraft Noise Reduction Laboratory. The test results show that the model performed satisfactorily and therefore the projected design will most likely meet the specifications.
Barna, P. S.↗
Preliminary investigation of interplanetary shock structure: Quasi-parallel shocks
Pioneer 9's magnetic field and plasma data were studied to develop arguments for or against the observation of oblique interplanetary shocks. Structural classifications are defined, and the justification for seeking these classifications in the solar wind are presented.
Greenstadt, E. W.↗
Visual reaction times during prolonged angular acceleration parallel the subjective perception of rotation
The effect of prolonged angular acceleration on choice reaction time to an accelerating visual stimulus was investigated, with 10 commercial airline pilots serving as subjects. The pattern of reaction times during and following acceleration was compared with the pattern of velocity estimates reported during identical trials. Both reaction times and velocity estimates increased at the onset of acceleration, declined prior to the termination of acceleration, and showed an aftereffect. These results are inconsistent with the torsion-pendulum theory of semicircular canal function and suggest that the vestibular adaptation is of central origin.
Mattson, D. L.↗
Standardized performance tests of collectors of solar thermal energy - A flat-plate copper collector with parallel mylar striping
Basic test results are reported for a flat plate solar collector whose performance was determined in a solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and one coolant flow rate. Collector efficiency is correlated in terms of inlet temperature and flux level.
Johnson, S. M.↗
Digital signal processing and control and estimation theory -- Points of tangency, area of intersection, and parallel directions
A number of current research directions in the fields of digital signal processing and modern control and estimation theory were studied. Topics such as stability theory, linear prediction and parameter identification, system analysis and implementation, two-dimensional filtering, decentralized control and estimation, image processing, and nonlinear system theory were examined in order to uncover some of the basic similarities and differences in the goals, techniques, and philosophy of the two disciplines. An extensive bibliography is included.
Willsky, A. S.↗
Spatially localized, shock-wave-induced continuous and very fast mixing between gases and liquid in parallel flow /An experimental study/
Shock-wave-induced patterns and turbulent supersonic shear flows over a stagnant bubble were determined for cases where recirculation and final mixing occurred within a very short time and within a distance of about 1 cm. The effect of a shock wave upon stratified laminas of gases in a shock tube was studied for a series of gases of different densities and molecular weights. Steady-state mixing of gas streams were investigated in wind tunnel experiments by means of a chemiluminescent reaction. Shock-wave-induced mixing which involves the introduction of a liquid jet into a supersonic gas stream is also described.
Devis, E.↗
Experimental study of the laminar-turbulent transition of a concave wall in a parallel flow
The instability of the laminar boundary layer flow along a concave wall was studied. Observations of these three-dimensional boundary layer phenomena were made using the hydrogen-bubble visualization technique. With the application of stereo-photogrammetric methods in the air-water system it was possible to investigate the flow processes qualitatively and quantitatively. In the case of a concave wall of sufficient curvature, a primary instability occurs first in the form of Goertler vortices with wave lengths depending upon the boundary layer thickness and the wall curvature. At the onset the amplification rate is in agreement with the linear theory. Later, during the non-linear amplification stage, periodic spanwise vorticity concentrations develop in the low velocity region between the longitudinal vortices. Then a meandering motion of the longitudinal vortex streets subsequently ensues, leading to turbulence.
Bippes, H.↗
Parallel computation of unsteady, three-dimensional, chemically reacting, nonequilibrium flow using a time-split finite-volume method on the Illiac IV
A description is presented of the split finite-volume method which is a viable numerical procedure for performing with the aid of a modern special purpose vector computer numerical simulation studies of complicated flow fields, including chemical reactions, about geometrically complex bodies. Such numerical studies are needed for the development of atmospheric entry vehicles such as the space shuttle. The equations which are approximated are quite general and can be used in studies of combustion, pollution, and other chemically reacting flow phenomena, where convective transport effects dominate the influence of radiative, viscous, and other transport mechanisms. The shock perturbed flow about a shuttle orbiter flying at a large angle of attack during atmospheric entry is illustrated. The method uses a time splitting of the convection differencing operator to achieve efficient data management.
Reinhardt, W. A.↗
Generation of a parallel X-ray beam and its use for testing collimators
A technique is described, by which a glass strip may be bent to match any curve of large radius of curvature, to a high degree of accuracy, so that it may be used as a glancing incidence X-ray or extreme ultraviolet optical element. The desired match is obtained by applying the optimum combination of end couples and by varying the cross-sectional moment of inertia along the length of the strip. A particular case, that of a parabola for use as a laboratory X-ray collimator, is considered in detail. The analysis predicts that a collimation of one or two arc seconds should be obtainable in practice, with simple and inexpensive apparatus. A prototype collimator to be used for the testing of space payloads using geometric (McGrath) collimators is described and laboratory results presented.
Underwood, J. H.↗
Stitch-bond parallel-gap welding for IC circuits
Stitch-bonded flatpacks are superior to soldered dual-in-lines where size, weight, and reliability are important. Results should interest designers of packaging for complex high-reliability electronics, such as that used in security systems, industrial process control, and vehicle electronics.
Chvostal, P.↗
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