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Resonance effects of electrostatic oscillations in the ionosphere.
Plasma resonance effects due to electrostatic oscillations of ionospheric electrons including dispersion and relaxation properties
Calculation of resonant effects in electron-impact excitation of positive ions Application to oxygen VII
The general reaction theory of Feshbach is applied to the calculation of resonant effects in near-threshold electron-positive-ion excitation. The theory divides configuration space into open- and closed-channel parts, resonance effects being described by the closed-channel part. The open-channel part is handled in a distorted-wave approximation to the set of open-channel coupled equations. Various methods are suggested for handling the closed-channel part. However, an 'attached-excited-target approximation' is used explicitly, which is further approximated by a set of uncoupled closed-channel equations. As an example, the 1 1S-2 1P excitation cross section of O VII below the 3 3S threshold is calculated. Various distorted-wave approximations are investigated and results from most of them are quite similar. Resonant effects arising from the attachment of the colliding electron with the 3 3S state are found to be small, but other close-lying n = 3 states have not yet been included.
Effective resonance integrals of separated tungsten isotopes
Effective resonance integral measurements of separated tungsten isotopes and natural tungsten relative to gold
A study of space contamination by means of the surface plasma resonance effect in grating diffraction
Surface plasma resonance effect in diffraction gratings and relation of effect to space contamination by spacecraft instruments
Numerical evaluation of barrier penetration and resonance effects on phase shifts
Quantum mechanical calculations to evaluate barrier penetration and resonance effects on phase shifts
Fluid immersion as a means for reducing resonance effects in rotary compensators.
Index-matching fluid immersion as means for reducing optical resonance effects in rotary compensators
Effective resonance integrals of separated tungsten isotopes from reactivity measurements.
Effective resonance integrals for separated tungsten isotopes and natural W and Au determined from epicadmium reactivity measurements
Numerical evaluation of barrier penetration and resonance effects on phase shifts.
Quantum mechanical calculations for Lennard- Jones potential show dependence of barrier penetration and resonance effects on phase shifts
Detection of Moving Targets Using Soliton Resonance Effect
The objective of this research was to develop a fundamentally new method for detecting hidden moving targets within noisy and cluttered data-streams using a novel "soliton resonance" effect in nonlinear dynamical systems. The technique uses an inhomogeneous Korteweg de Vries (KdV) equation containing moving-target information. Solution of the KdV equation will describe a soliton propagating with the same kinematic characteristics as the target. The approach uses the time-dependent data stream obtained with a sensor in form of the "forcing function," which is incorporated in an inhomogeneous KdV equation. When a hidden moving target (which in many ways resembles a soliton) encounters the natural "probe" soliton solution of the KdV equation, a strong resonance phenomenon results that makes the location and motion of the target apparent. Soliton resonance method will amplify the moving target signal, suppressing the noise. The method will be a very effective tool for locating and identifying diverse, highly dynamic targets with ill-defined characteristics in a noisy environment. The soliton resonance method for the detection of moving targets was developed in one and two dimensions. Computer simulations proved that the method could be used for detection of singe point-like targets moving with constant velocities and accelerations in 1D and along straight lines or curved trajectories in 2D. The method also allows estimation of the kinematic characteristics of moving targets, and reconstruction of target trajectories in 2D. The method could be very effective for target detection in the presence of clutter and for the case of target obscurations.
Resonance Effects in the NASA Transonic Flutter Cascade Facility
Investigations of unsteady pressure loadings on the blades of fans operating near the stall flutter boundary are carried out under simulated conditions in the NASA Transonic Flutter Cascade facility (TFC). It has been observed that for inlet Mach numbers of about 0.8, the cascade flowfield exhibits intense low-frequency pressure oscillations. The origins of these oscillations were not clear. It was speculated that this behavior was either caused by instabilities in the blade separated flow zone or that it was a tunnel resonance phenomenon. It has now been determined that the strong low-frequency oscillations, observed in the TFC facility, are not a cascade phenomenon contributing to blade flutter, but that they are solely caused by the tunnel resonance characteristics. Most likely, the self-induced oscillations originate in the system of exit duct resonators. For sure, the self-induced oscillations can be significantly suppressed for a narrow range of inlet Mach numbers by tuning one of the resonators. A considerable amount of flutter simulation data has been acquired in this facility to date, and therefore it is of interest to know how much this tunnel self-induced flow oscillation influences the experimental data at high subsonic Mach numbers since this facility is being used to simulate flutter in transonic fans. In short, can this body of experimental data still be used reliably to verify computer codes for blade flutter and blade life predictions? To answer this question a study on resonance effects in the NASA TFC facility was carried out. The results, based on spectral and ensemble averaging analysis of the cascade data, showed that the interaction between self-induced oscillations and forced blade motion oscillations is very weak and can generally be neglected. The forced motion data acquired with the mistuned tunnel, when strong self-induced oscillations were present, can be used as reliable forced pressure fluctuations provided that they are extracted from raw data sets by an ensemble averaging procedure.
The surface plasmon resonance effect in holography.
A hologram has been made using a surface plasmon resonance wave as the reference beam. The surface wave was stimulated on a 1200-line/mm aluminum reflection grating that was coated with a thin layer of high-resolution photographic emulsion. Experimental results are presented.
Paramagnetic resonance effect in viscoelastic materials Annual progress report, 1 Jan. - 31 Dec. 1968
Electron paramagnetic resonance investigation of fracture in viscoelastic materials
Third-order resonance effects and the nonlinear stability of drop oscillations
The three-dimensional nonlinear oscillations of an isolated, inviscid drop with surface tension are studied by a multiple timescale analysis and pre-averaging applied to the variational principle for the appropriate Lagrangian. Amplitude equations are derived which describe the generic cubic resonance caused by the spatial degeneracy of the eigenfrequencies of the linear normal modes. This resonant coupling leads to the instability of the finite amplitude axisymmetric oscillations to small nonaxisymmetric perturbations, as is demonstrated here for the three- and four-lobed normal modes. Solutions to the interaction equations that describe finite amplitude, nonaxisymmetric traveling-wave solutions are also obtained and their stability is investigated. A nongeneric cubic resonance between the two-lobed and four-lobed oscillatory modes leads to quasi-periodic motions.
Resonance Effects in Axisymmetrically-Forced Bubble Oscillations
Large bubbles are levitated in a primary acoustic field, trapped slightly above the pressure nodes.
Cyclotron resonance effects on stochastic acceleration of light ionospheric ions
The production of energetic ions with conical pitch angle distributions along the auroral field lines is a subject of considerable current interest. There are several theoretical treatments showing the acceleration (heating) of the ions by ion cyclotron waves. The quasi-linear theory predicts no acceleration when the ions are nonresonant. In the present investigation, it is demonstrated that the cyclotron resonances are not crucial for the transverse acceleration of ions by ion cyclotron waves. It is found that transverse energization of ionospheric ions, such as He(+), He(++), O(++), and O(+), is possible by an Electrostatic Hydrogen Cyclotron (EHC) wave even in the absence of cyclotron resonance. The mechanism of acceleration is the nonresonant stochastic heating. However, when there are resonant ions both the total energy gain and the number of accelerated ions increase with increasing parallel wave number.
Gravitational spurs and resonances - Effects of small mass disturbers in spiral galaxy disks
In the present simulations of a disturber in a complete stellar disk without the restrictive assumption, the disturber parameters of the NGC 206 cloud in M 31 were assumed as a realistic example. The resulting spur around the disturber was comparable in shape, size, and strength to Julian and Toomre's (1966) results. In addition, a complicated evolving pattern of strong density peaks appeared well inside and outside the disturber's orbit. Simulation with a ten-times-more-massive disturber showed a more clearly defined version of the same initial pattern, two spiral arms of density peaks rotating with the disturber in the stronger arm. The orbital radii of the density peaks correspond to those of epicyclic resonances with the orbiting disturber potential.
Paramagnetic resonance effect in viscoelastic materials semiannual progress report, 1 jul. - 31 dec. 1967
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