Origin of threshold-response delay in ferrite memory cores.
Time logarithmic switching to explain anomalous delay in threshold response of MgMnZn ferrite memory cores
Barker, R. C.↗
SEARCH · Search NASA
Results for “LOGARITHM”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
A seismic refraction system for lunar use.
Miniaturized seismic refraction system for manned lunar landings consisting of geophones, three channel amplifier, calibrator and logarithmic compressor
Kerr, J.↗
Log amplifier instrument measures physiological biopotentials over wide dynamic range
To record biopotentials with extreme dynamic ranges, biopotential inputs are capacitatively coupled to a miniature, low power, solid-state signal conditioner consisting of a two-stage differential preamplifier that has a low noise figure. The ouput of the preamplifier uses diodes to provide an overall gain which is nearly logarithmic.
Kado, R. T.↗
Low-frequency sound velocity in CO sub 2 near the critical point
LF sound velocity measurement in carbon dioxide near critical point, noting existence of logarithmic divergence
Carome, E. F.↗
Quasilog scaler
Quasi-logarithmic readout of conventional binary scaler provided by reduced logic system following generalized equations
Weissman, R.↗
Fast Two-Dimensional Fourier Transform
Algorithm for Fast Two Dimensional Fourier Transform requiring logarithm additions and multiplication
Hong, J. P.↗
A classification of impact craters
Planetary and lunar meteorite craters classification according to radius logarithm to base ten, covering diameter size from 2 microns to 2000 km
Hoerz, F.↗
Analytical solution for the wind-driven circulation in a lake containing an island
An analysis was carried out to determine analytically the effect of an island on the wind driven currents in a shallow lake (or sea). A general analysis is developed that can be applied to a large class of lake and island geometries and bottom topographies. Detailed numerical results are obtained for a circular island located eccentrically or concentrically in a circular lake with a logarithmic bottom topography. It is shown that an island can produce volume flow (vertically integrated velocities) gyres that are completely different from those produced by a normal basin without an island. These gyres in the neighborhood of the island will produce different velocity patterns, which include the acceleration of flow near the island shore.
Goldstein, M. E.↗
Integrated circuit electrometer and sweep circuitry for an atmospheric probe
The design of electrometer circuitry using an integrated circuit operational amplifier with a MOSFET input is described. Input protection against static voltages is provided by a dual ultra low leakage diode or a neon lamp. Factors affecting frequency response leakage resistance, and current stability are discussed, and methods are suggested for increasing response speed and for eliminating leakage resistance and current instabilities. Based on the above, two practical circuits, one having a linear response and the other a logarithmic response, were designed and evaluated experimentally. The design of a sweep circuit to implement mobility measurements using atmospheric probes is presented. A triangular voltage waveform is generated and shaped to contain a step in voltage from zero volts in both positive and negative directions.
Zimmerman, L. E.↗
Time and temperature dependent modulus of pyrrone and polyimide moldings
A method is presented by which the modulus obtained from a stress relaxation test can be used to estimate the modulus which would be obtained from a sonic vibration test. The method was applied to stress relaxation, sonic vibration, and high speed stress-strain data which was obtained on a flexible epoxy. The modulus as measured by the three test methods was identical for identical test times, and a change of test temperature was equivalent to a shift in the logarithmic time scale. An estimate was then made of the dynamic modulus of moldings of two Pyrrones and two polyimides, using stress relaxation data and the method of analysis which was developed for the epoxy. Over the common temperature range (350 to 500 K) in which data from both types of tests were available, the estimated dynamic modulus value differed by only a few percent from the measured value. As a result, it is concluded that, over the 500 to 700 K temperature range, the estimated dynamic modulus values are accurate.
Lander, L. L.↗
Lifting-surface theory for calculating the loading induced on a wing by a flap
A method is described for using lifting-surface theory to obtain the pressure distribution on a wing with a trailing-edge flap or control surface. The loading has a logarithmic singularity at the flap edges, which may be determined directly by the method of matched asymptotic expansions. Expressions are given for the singular flap loading for various flap hinge line and side edge geometries, both for steady and unsteady flap deflection. The regular part of the flap loading must be obtained by inverting the lifting-surface-theory integral equation relating the pressure and the downwash on the wing: procedures are described to accomplish this for a general wing and flap geometry. The method is applied to several example wings, and the results are compared with experimental data. Theory and test correlate well.
Johnson, W. A.↗
Dynamics of a supersonic inlet-engine combination subjected to disturbances in fuel flow and inlet overboard bypass airflow
An axisymmetric mixed-compression supersonic inlet and a single-spool turbojet engine were dynamically tested at Mach 2.5. The propulsion system was subjected to sweep-frequency sinusoidal disturbances of either inlet overboard bypass airflow. The disturbances were at a logarithmic sweep rate of 1 decade per minute. Dynamic responses were taken of signals throughout the propulsion system. Selected signals were reduced relative to the prime propulsion system parameters. The experimental data are presented in Bode plots. Most of the plots are for a frequency range of 1.0 to 50 hertz.
Wallhagen, R. E.↗
Bearing strength of the lunar soil
A discussion is presented on the bearing strength and bearing load-penetration relations in lunar soil. These were measured in air as a function of bulk density. It was found that the relation between bulk density and the logarithm of the bearing capacity is about linear. Shapes of the load vs penetration curves were observed to be similar to those obtained with particulate material of terrestrial origin.
Jaffe, L. D.↗
Introduction
An analysis of the principles of strapdown inertial platforms is presented, and the advantages of the strapdown system as compared to other stabilized systems are discussed. The application of the rebalance loop to continuously restore the position of sensor output axes is described. The attitude logarithms and the rebalance electronics which are required for accurate navigation are examined.
Hung, J. C.↗
Surface tensions of propellants
An apparatus is described for determining the surface tension of propellants by measuring the maximum bubble pressure using two capillaries of different bores. The innovation is the use of a pressure transducer coupled to a bridge supply and a strip chart recorder for registering the development of the pressure difference as the bubble is formed and released. This enables the measurements to be made under controlled atmospheres and to be remotely operated. Preliminary experiments were done on propellant-grade hydrazine and monomethylhydrazine, and on purified hydrazine, at temperatures between 275.4 and 353.2 K. Straight-line expressions and logarithmic expressions reproduce equally well the variation of surface tension with temperature. Contaminated hydrazine, pre-exposed to coupons of 6Al-4V titanium alloy for long periods, gives slightly higher values of surface tension.
Razouk, R.↗
Viscel: A general purpose computer program for analysis of linear viscoelastic structures, volume 2
The VISCEL program is a general purpose computer program developed for equilibrium analysis of linear viscoelastic structures. The program is written in FORTRAN 5 language to operate on the Univac 1108 computer under the EXEC 8 operating system. The program, an extension of the linear equilibrium problem solver ELAS, is an updated and extended version of its earlier form written for the IBM 7094 computer. Finite element matrix displacement approach coupled with the synchronized material property concept, utilizing incremental time steps, was adopted for the solution presented. The step-by-step procedure involves solution of recursive equations in the time domain, which takes into account the memory of material properties. Incremental and accumulative displacements and stresses are obtained at the end of each time step. In order to minimize the extent of computations resulting from accumulative effects of material memory, the program provides an option which enables the employment of constant time steps in the logarithmic scale. Program documentation is presented.
Gupta, K. K.↗
Ultrahigh energy photons, electrons, and neutrinos, the microwave background, and the universal cosmic-ray hypothesis
The production of ultrahigh energy photons, electrons and neutrinos as the decay products of pions produced in photomeson interactions between cosmic ray nucleons and the blackbody microwave background is discussed in terms of the resultant energy spectra of these particles. Simple asymptotic formulas are given for calculating the ultrahigh energy photon spectrum predicted for the universal cosmic ray hypothesis and the resulting spectra are compared with those obtained previously by numerical means using a different propagation equation for the photons. Approximate analytic solutions for the photon spectra are given in terms of simple power-law energy functions and slowly varying logarithmic functions.
Stecker, F. W.↗
Divergence of the total cross section for three body rearrangement collisions with coulomb interactions
Three charged particles 1, 2, 3 collide according to the reaction 1+(2+3) yields (1+3)+2, where (2+3) and (1+3) are hydrogenlike bound states. It is shown when (1+3) is in a highly excited state n, due to the repulsive potential, the cross section in the first Born approximation behaves as 1/n which makes the total cross section to diverge like ln n. The total cross sections in the higher orders of the Born approximation are similarly divergent logarithmically.
Omidvar, K.↗