Variational bounds in positron atom scattering
First order adiabatic correlation function for determining variational bounds in positron-atom scattering
Drachman, R. J.↗
SEARCH · Search NASA
Results for “Correlation Functions”
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.
Shielding in Anisotropic Plasmas
Shielding by anisotropic electron plasmas with nonzero streaming, calculating shielding clouds and density-density correlation functions
Joyce, G.↗
Quantum theory of an optical maser. II - Spectral profile.
Quantum theory of optical maser, calculating laser radiation spectrum from two time correlation function derived from equations of motion
Lamb, W. E., Jr.↗
High speed correlator.
Computational procedure and circuitry of correlator for real time computation of correlation function of signals at 30 points simultaneously
Hooper, E. B., Jr.↗
Combined Doppler and collision broadening.
Spectral lines combined Doppler and collision effect studied by statistical correlation function for time varying amplitude of classical oscillators
Foley, H. M.↗
Off-line correlation analysis of nonstationary signals.
Off-line analysis for estimating correlation functions of signals generated by nonstationary processes, using hybrid or digital computers
Knight, J. R.↗
Variational bounds in positron-atom scattering.
Adiabatic correlation function for variational lower bounds on positron-atom elastic scattering phase shifts for hydrogen and helium atoms
Drachman, R. J.↗
Test particle method in kinetic theory of a plasma
Relationship between test particle correlation functions and conditional probability functions as established in studies of kinetic theory of plasmas
Matsuda, K.↗
Coding and synchronization - The signal design problem.
Synchronization in coded communication systems, considering phase lock loop and square wave correlation function
Stiffler, J. J.↗
Range and spatial variation of the Kondo spin- compensated state.
Spin compensated state of localized magnetic impurity moment in space, calculating size range of magnetic impurity spin/conduction electron spin correlation function
Bose, S. M.↗
Picosecond pulse measurement by two-photon excitation of photographic film
Technique shoots two broad light beams onto a photosensitive surface which responds nonlinearly to the intensity in the beams. The resultant signal contains a component depending on the intensity correlation function between the two light beams.
Billman, K. W.↗
A simple gigacycle correlator
Gigacycle correlator involving sampling oscilloscopes for real time display of correlation functions over adjustable time interval, discussing design and performance
Alexeff, I.↗
Power spectrum of light scattered by two-level systems
Power spectrum of light scattered by two level atom driven by monochromatic electric field obtained from atomic dipole moment correlation function
Mollow, B. R.↗
Measurements of photon correlations of second harmonic generated light
CW second harmonic He-Ne laser light second order intensity correlation function measurements
Davidson, F.↗
Noise analysis of nucleate boiling
The techniques of noise analysis have been utilized to investigate nucleate pool boiling. A simple experimental setup has been developed for obtaining the power spectrum of a nucleate boiling system. These techniques were first used to study single bubbles, and a method of relating the two-dimensional projected size and the local velocity of the bubbles to the auto-correlation functions is presented. This method is much less time consuming than conventional methods of measurement and has no probes to disturb the system. These techniques can be used to determine the contribution of evaporation to total heat flux in nucleate boiling. Also, these techniques can be used to investigate the effect of various parameters upon the frequency response of nucleate boiling. The predominant frequencies of the power spectrum correspond to the frequencies of bubble generation. The effects of heat input, degree of subcooling, and liquid surface tension upon the power spectra of a boiling system are presented. It was found that the degree of subcooling has a more pronounced effect upon bubble size than does heat flux. Also the effect of lowering surface tension can be sufficient to reduce the effect of the degree of subcooling upon the size of the bubbles.
Mcknight, R. D.↗
Bayesian recursive image estimation.
A procedure for recursively estimating images that are characterized statistically by the mean and correlation functions associated with the random process representing the brightness level is proposed for the case where the images are corrupted by additive noise. First, a dynamic model is developed with a response characteristic which matches that of the scanner output (the input of the estimator is the output of a horizontal line scanner) in a statistical sense. Such models have the form of an ordinary differential or difference equation with white noise input. An insignificant approximation is introduced by using a constant-coefficient model. The appropriate model is a vector valued difference equation with the solution representing a vector Markov process. The next step is to obtain the minimum mean square estimate of the image by using a Kalman filter. Since the image estimation is an interpolation problem, two successive runs over the observation are performed in opposite directions and the resultant estimates are averaged. Examples are included for illustration.
Nahi, N. E.↗
Baysian recursive image estimation.
Discussion of a statistical procedure for treatment of noise-affected images to recover unaffected images by recursive processing with noise background elimination. The feasibility of the application of a recursive linear Kalman filtering technique to image processing is demonstrated. The procedure is applicable to images which are characterized statistically by mean and correlation functions. A time invariant dynamic model is proposed to provide stationary statistics for the scanner output.
Nahi, N. E.↗
The pseudonoise test set: Communication system's performance evaluation based upon RMS error testing
A pseudonoise (PN) test set was built to provide a relatively easy means of accurately determining the end-to-end rms error introduced by a communication system when subjected to wideband data. It utilizes a filtered pseudorandom sequence generator as a wideband data source, providing a convenient means for digitally delaying the input reference signal for comparison with the distorted test communication system output. In addition to providing a means to measure the end-to-end rms error and the average delay of a communication system, the PN test set also provides a means to determine the tested system's impulse response and correlation function. The theory of PN testing is discussed in detail along with the most difficult aspects of implementation, the building of matched filter pairs. Both analytical and empirical results are reported which support the contentions that this is an accurate and practical way to acquire figures of merit for complete communication systems.
Wallace, G. R.↗