Noise and equivalent circuit of double injection.
Silicon double injection diode, discussing HF noise measurement, Nyquist noise equivalent circuit for double injection process and source of LF noise
Bilger, H. R.↗
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Holographic testing with a double reference beam
Image of unstressed object is taken with reflected beam and one reference beam. Object is then stressed and second (double) exposure is made. Developed film plate provides double exposure hologram that can be projected by simultaneous illumination with both reference beams. Appearance of multiple images may be eliminated while manipulating fringe patterns.
Stuckenberg, F. H.↗
Effects of certain control-system nonlinearities on stability and pointing of an attached double-gimbal experiment package in presence of random crew-motion disturbances
The effects of two types of control-system nonlinearities, sensor deadband and actuator breakout torque, on the pointing capability of a Apollo Telescope Mount (ATM) double-gimbal experiment isolation and control system are investigated. A composite structural model of a flexible experiment package connected through frictionless double gimbals to a flexible carrier vehicle is used for this investigation. Contributions of the primary carrier control system to experiment pointing are neglected. Pointing errors onboard the experiment package due to random crew-motion input into the carrier vehicle are computed. A stability investigation is performed to verify control-system stability with nominal nonlinearities and gains. Indications are that there is no stability problem due to the nonlinearities. A nonlinearity sensitivity study is carried out to determine the effects on pointing accuracy. Its results indicate that nominal ATM control system nonlinearities limit the pointing accuracy to approximately 0.4 arc second in the presence of crew motion. Methods of reducing the error to less than 0.1 arc second are discussed.
Shaughnessy, J. D.↗
Internal upconversion and doubling of an optical parametric oscillator to extend the tuning range.
Efficient extension of the tuning range of a 1.09-1.95-micron parametric oscillator to 0.435-0.975 microns by upconversion and doubling internally to the oscillator cavity is reported. Unlike previously studied external mixing, internal upconversion and doubling yielded uniform powers of 30 and 60 kW, respectively, over the entire extended tuning range with an unfocused 2-mm ruby laser pump beam of 750 kW.-
Campillo, A. J.↗
Transition region response of the symmetric double probe and its application in the lower ionosphere.
Assessment of the floating double probe technique for in situ measurements of the plasma temperature in the D region of the ionosphere. The effects of ion-atom collisions on the current-voltage characteristic of a symmetric double-probe system are reviewed in connection with the determination of the temperature of a completely thermalized plasma. The manner in which this technique can be implemented for a rocket-borne experiment is described, and an experimental current-voltage characteristic obtained in the earth's lower atmosphere is presented and discussed.
Szuszczewicz, E. P.↗
Double scattering corrections for the theory of the sun's aureole
Double scattering corrections for aureole radiances are calculated by adding the effects of two successive single scatterings. Atmospheric absorption, polarization, and variation of refractive index with altitude are ignored. Corrections due to spherical atmosphere were taken into account by the use of a generalized Chapman function. Realistic scattering phase functions based upon the Lorenz-Mie theory and model altitude-size distribution are used. The model distribution is assumed to be representable in terms of two separable particulate components. It was found that for a moderately clear day, tau (0) is approximately equal to 0.5, and for forward scattering angles, the radiance, B sub 2, due to double scattering is less than 6 percent of that due to single scattering.
Deepak, A.↗
Spatial frequency doubling - Retinal or central
When a wide field is sinusoidally modulated both in space and in time, the spatial frequency of the pattern will appear doubled at high rates of modulation. Kelly (1966) proposed that this illusion is due to temporal integration of the nonlinear brightness response of the visual system. The anatomical locus of this temporal integrator is uncertain, and could be subcortical. Results indicate that spatial frequency doubling follows binocular disparity detection and is thus a cortical phenomenon.
Richards, W.↗
A steering law for three double-gimbal control moment gyro systems
A steering law for three double-gimbal control moment gyro (CMG) systems is proposed. This steering law is applicable to systems with almost any configuration of CMGs and the CMG-out operation needs no special modification. Examples of three double gimbal CMG systems in an orthogonal configuration and in a parallel configuration are shown along with the results of digital simulations. Simulation results show that any command torque can always be met except when the system is in a singular state and that, whenever the system is in, or close to, a singularity, the steering law drives the system state out of the vicinity of the singularity.
Yoshikawa, T.↗
Effect of design features on performance of a double-annular ram-induction combustor
An extensive test program was undertaken to determine the effect of many design features such as the size and number of air scoops, and the type of diffuser airflow distribution to use to optimize performance of a double-annular ram-induction combustor of 94 cm outer diameter. Six combustor configurations were tested. It was found that a snouted double annular combustor built with 256 ram-induction air scoops with a combustor open area giving a total pressure loss of 5.0 percent at a diffuser inlet Mach number of 0.25 gave the best overall performance of the configurations tested.
Schultz, D. F.↗
Polarization tracking of a partially coherent signal using a double loop
We consider the problem of simultaneously estimating the phase and polarization angles of a linearly polarized electromagnetic wave. The solution of this problem has applications to space communications and ionospheric probing. The nonlinear stochastic characteristics of a cross-coupled double-loop implementation for the tracker are evaluated using the multidimensional Fokker-Planck equation. The exact stationary probability density is found for a special case of equal signal-to-noise ratio (SNR) in the two loops. The stationary probability density is obtained for a general class of double loops when the two loop bandwidths differ greatly.
Ohlson, J. E.↗
Pulsation of double-mode Cepheids and comments on the problem of Cepheid masses
The double mode Cepheids are stars, found near the low luminosity end of the Population I Cepheid strip, which display a mixture of modes where the longer of the two periods is between two and four days. It is usually assumed that the mixture is composed of fundamental and first harmonic modes. In order to obtain the various physical parameters for the double mode Cepheids, the pulsation constant, Q, is determined in the period-mean-density relation for realistic stellar models, by making use of a linearized nonadiabatic analysis. By studying a large number of models that obey a variety of mass luminosity relations, simple fitting formulas for the pulsation constants are obtained.
King, D. S.↗
Thermal performance of honeywell double covered liquid solar collector
The test procedures and results obtained during an evaluation test program to determine the outdoor performance characteristics of the Honeywell liquid solar collector are presented. The program was based on the thermal evaluation of a Honeywell double covered liquid solar collection. Initial plans included the simultaneous testing of a single covered Honeywell collector. During the initial testing, the single covered collector failed due to leakage; thus, testing continued on the double covered collector only. To better define the operating characteristics of the collector, several additional data points were obtained beyond those requested.
Losey, R.↗
Double ionization of CO2 by photon impact
Double ionization of CO2 by photon impact from the double-ionization threshold at energies of 36.2 eV (342 A) to 110 eV (113 A) has been observed. The ratio of doubly to singly charged ions shows a linear rise with photon energy for approximately 15 eV above the threshold and reaches a constant value of about 2% between 67 and 110 eV.
Samson, J. A. R.↗
Double dither loop for pseudonoise code tracking
A new type of phase detector for pseudonoise code tracking is introduced and analyzed in comparison with the delay lock loop (DLL) and tau-dither loop (TDL) configurations. It is shown that the double dither loop (DDL) combines the best features of the DLL and the TDL in that the DDL is insensitive to gain and offset imbalances and does not suffer the 3-dB degradation in noise performance typically associated with the TDL. The double dither concept is applicable to other dual channel detectors such as in a Costas-type carrier tracking loop.
Hopkins, P. M.↗
Design curves for double-heterojunction laser diodes
This paper reviews theoretical double-heterojunction laser design curves relating the structure with the transverse mode order able to propagate, the degree of radiation confinement to the active region, the maximum field intensity within the device, and the radiated beam shape. The curves presented are general and applicable to any double-heterojunction structure where the spacing of the heterojunctions and the refractive index in the relevant regions are known.
Butler, J. K.↗
Study report on a double isotope method of calcium absorption
Some of the pros and cons of three methods to study gastrointestinal calcium absorption are briefly discussed. The methods are: (1) a balance study; (2) a single isotope method; and (3) a double isotope method. A procedure for the double isotope method is also included.
Source record↗
Numerical simulation of plasma double layers
Numerical simulation results are presented for a plasma double layer, the computer model being a finite one-dimensional particle-in-cell plasma with specified potential difference across the system. A single pulse is formed which crosses the system with constant velocity; this is followed by the formation of a potential drop across a limited region of the plasma. An approximate expression relating the spatial extent of the double layer and the potential drop is presented. Electron and ion beams are generated which tend to lead to instabilities in the upstream and downstream regions.
Joyce, G.↗
Double metalization for VLSI
Postsintering process increases yield of double-layer metal conductors to almost 100 percent. When wafers containing double-metalized chips are sintered, metal layers react with oxide film remaining in insulation layer holes, breaking it up so that it no longer impedes electric current. Cooling also mechanically disrupts oxide film.
Trotter, J. D.↗