Showing papers on "Amplitude published in 1980"
TL;DR: In this paper, the velocity averaging of collision cross sections produces non-Lorentz line shapes, even at densities where Doppler broadening is not apparent, using a model in which the collision broadening depends on a simple velocity power law, and the effect of the modified profile on experimental measures of linewidth, shift and amplitude is examined and an improved approximate line shape is derived.
Abstract: The velocity averaging of collision cross sections produces non‐Lorentz line shapes, even at densities where Doppler broadening is not apparent. The magnitude of the effects will be described using a model in which the collision broadening depends on a simple velocity power law. The effect of the modified profile on experimental measures of linewidth, shift and amplitude will be examined and an improved approximate line shape will be derived.
185 citations
TL;DR: Frequency-selective optical couplers in which a periodic perturbation in refractive index induces contradirectional power transfer in parallel single-mode waveguides are analyzed and it is shown that by varying the amplitude of the periodic perturbing along he direction of propagation, the sidelobes present for the case of a uniform perturbations can be substantially reduced.
Abstract: Frequency-selective optical couplers in which a periodic perturbation in refractive index induces contradirectional power transfer in parallel single-mode waveguides are analyzed. Expressions for the spectral response are obtained by solving the coupled-mode equations. It is shown that by varying the amplitude of the periodic perturbation along he direction of propagation, the sidelobes present for the case of a uniform perturbation can be substantially reduced. Calculations are made of the mode propagation constants and coupling parameters for two rectangular-core waveguides with a periodic surface corrugation in the region between them. By using these results, design parameters and theoretical performance characteristics for a coupler with high transfer efficiency, low cross talk, and low reflection efficiency in the primary waveguide are determined.
138 citations
TL;DR: In this article, a linear stability analysis of the Laminar flow of air over water confined between two infinite parallel plates was made and the conditions at which small amplitude surface waves first begin to grow were determined.
Abstract: The fully developed laminar flow of air over water confined between two infinite parallel plates was used to study nonlinear effects in the generation of surface waves. A linear stability analysis of the basic flow was made and the conditions at which small amplitude surface waves first begin to grow were determined. Then, following Stewartson & Stuart (1971), the nonlinear stability of the flow was examined and the usual parabolic equation with cubic nonlinearity obtained for the amplitude of the disturbances. The calculation of the linear stability characteristics and the coefficients appearing in the amplitude equation was a lengthy computational task, with most interest centred on the coefficient of the nonlinear terms in the amplitude equation. In two profiles, used as crude models of a boundary layer flow of air over water, the calculations indicated that, over a range of parameters, the non-linear effects would reduce the growth rate of the surface waves and hence lead to equilibrium amplitude waves.
126 citations
Patent•
03 Nov 1980
TL;DR: In this article, a particle separator for sorting particles suspended in a liquid according to certain characteristics, including a method of and apparatus for detecting a change in the droplet breakoff point of a liquid jet stream which is subjected to vibrations.
Abstract: A particle separator for sorting particles suspended in a liquid according to certain characteristics, including a method of and apparatus for detecting a change in the droplet breakoff point of a liquid jet stream which is subjected to vibrations. The vibrations produce amplitude undulations on the surface of the jet stream. The amplitude of the undulations is monitored or interrogated at a fixed point on the jet stream prior to the breakoff point. A change in amplitude of the undulations at that fixed point produces a signal voltage the value of which is proportional to the amplitude change. This signal voltage may be used (1) to alert the operator that a change has occurred in the point at which the jet stream is breaking up into droplets, (2) to automatically control the intensity of the vibrations for restoring the amplitude of undulation at that fixed point to its original state, or (3) to automatically disable the sorting portion of the apparatus. Any one or any combination of the foregoing three happenings can be utilized.
112 citations
TL;DR: In this article, the relationship between nonlinear wave coupling and the properties of the bispectrum is investigated for the case of three-wave coupling, in particular, the dependence of the phase of the Bispectrum, the direction of power flow between modes, and the sign of the skewness parameter, on the nonlinear amplitude variation and coupling coefficient.
Abstract: The relationship between nonlinear wave coupling and the properties of the bispectrum are investigated for the case of three‐wave coupling. In particular, the dependence of the phase of the bispectrum, the direction of power flow between modes, and the sign of the skewness parameter, on the nonlinear amplitude variation and coupling coefficient, is analytically investigated and found to be in good agreement with experimental observations.
109 citations
TL;DR: In this article, whispering gallery rays are modeled as a sum of whispering galley waves, which propagate in a waveguide composed of a simple high velocity mantle lid underlain by a low velocity zone.
Abstract: Teleseismic Pn waves are modeled as a sum of whispering galley waves, which propagate in a waveguide composed of a simple high velocity mantle lid underlain by a low velocity zone. This model is able to account for those Pn wave propagation properties that are not dominated by scattering, i.e., their apparent velocity and lack of long period energy. Pn apparent velocity data constrain the P wave velocity gradient in the upper 100 km of mantle to be low; dvp/dz<0.001 s−1. The whispering gallery rays are shown to have significant amplitude (when compared to the direct P wave) and to have spectra that rapidly fall off at long periods. Yet this model cannot account for certain details of the observed Pn amplitude spectra. Most important among these is the spectral ratio of Pn to P, which the model underestimates by a factor of 10. Nevertheless, the model presents a useful framework for understanding some characteristics of Pn wave propagation and provides an estimate of the distribution of energy with depth in the Pn waves.
88 citations
TL;DR: It is demonstrated that the modulation transfer function of the coherent four-wave process mixing can be controlled by the amplitude of externally applied field E0.
Abstract: Dependence of phase-conjugate wave-front reflectivity on the spatial frequency of the dynamic hologram recorded in Bi12SiO20 crystals is analyzed. Depending on the respective values of applied field E0 and fringe spacing Λ, drift or diffusion of the photocarriers dominates the space-charge buildup and affects the phase-conjugate wave-front intensity differently. It is demonstrated that the modulation transfer function of the coherent four-wave process mixing can be controlled by the amplitude of externally applied field E0. Experimental results are interpreted on the basis of the dynamic theory of Kukhtarev et al.
85 citations
TL;DR: The full amplitude equation as discussed by the authors is derived directly from the hydrodynamic equations for both free and rigid upper and lower boundaries, including the interaction parameter of nonparallel rolls, for both boundary conditions and all Prandtl numbers.
Abstract: The full amplitude equation (as introduced by Newell and Whitehead and Segel) is derived directly from the hydrodynamic equations for both ’’free’’ and ’’rigid’’ upper and lower boundaries. The coefficients involved, including the interaction parameter of nonparallel rolls, are explicitly calculated for both boundary conditions and all Prandtl numbers.
85 citations
Patent•
14 Aug 1980
TL;DR: In this paper, an apparatus for automated diagnosis of automobile engine electrical system waveform patterns is described. Butler et al. employed an addressable random access memory which stores digitized information concerning the waveform and employed a tracking analog-to-digital converter using comparator means which also provided a waveform peak detector.
Abstract: An apparatus which permits the automated diagnosis of automobile engine electrical system waveform patterns is disclosed. Employed in conjunction with an addressable random access memory which stores digitized information concerning the waveform are further means which logarithmically reduce input amplitude values of the waveform and coordinates sampling times for the waveform with engine RPM so that the memory capacity is fully utilized. Input conversion of the waveform is accomplished by a tracking analog-to-digital converter using comparator means which also provides a waveform peak detector. Upon an address command, the memory output is input into a read only memory which provides an anti-log conversion of the logarithmic value stored in the memory, thereby providing an output corresponding to an actual value signal.
85 citations
TL;DR: It is shown that, whereas true time reversal of an amplitude pulse is not possible with continuous-wave pumping, this can be achieved by short-pulse pumping of a long, narrow, nonlinear medium, although time-dependent phase variations are not time reversed.
Abstract: Four-wave mixing with optical pulses is considered analytically. It is shown that, whereas true time reversal of an amplitude pulse is not possible with continuous-wave pumping, this can be achieved by short-pulse pumping of a long, narrow, nonlinear medium, although time-dependent phase variations are not time reversed.
84 citations
TL;DR: In this article, a general theory of the motion of a two-level atom in a resonant or near-resonant electromagnetic wave of arbitrary amplitude and phase, including effects of radiative relaxation due to interaction with the quantized vacuum field, is developed from first principles.
Abstract: A general theory of the motion of a two-level atom in a resonant or near-resonant electromagnetic wave of arbitrary amplitude and phase, including effects of radiative relaxation due to interaction with the quantized vacuum field, is developed from first principles. Particular emphasis is placed on the effects of quantum-mechanical fluctuations of the radiation force and on the associated diffusion of atomic momentum due to spontaneous and induced absorption and emission processes. Analytic results and numerical examples are presented for (1) the lower bound on the temperature achievable by radiation cooling in a standing wave tuned below resonance, (2) the heating rate in a strong resonant standing wave, (3) the maximum confinement time for an atom in a Gaussian radiation trap, (4) the deflection and spreading of an atomic beam transversely illuminated by a strong resonant running wave, and (5) the transverse cooling of an atomic beam by a strong running wave tuned below resonance.
TL;DR: In this article, a waveform memory device read out type and a frequency information generator for generating a plurality of sets of frequency informations each set consisting of a subplurality of frequencies and corresponding to each of the tone pitches of the depressed keys in a keyboard, an accumulator for repeatedly accumulating the frequency information selected by the selector to produce an increasing accumulated value, a wave form memory device for storing the amplitude values at successive sampling points in one period of a sine wave utilized to form a desired musical waveform.
Abstract: The musical instrument is of a waveform memory device read out type and comprises a frequency information generator for generating a plurality of sets of frequency informations each set consisting of a subplurality of frequency informations and corresponding to each of the tone pitches of the depressed keys in a keyboard, a selector for selecting one, at a time and one after another, of the subplurality of frequency informations generated by the frequency information generator for each one key depressed, an accumulator for repeatedly accumulating the frequency information selected by the selector to produce an increasing accumulated value, a waveform memory device for storing the amplitude values at successive sampling points in one period of a sine wave utilized to form a desired musical waveform, a comparator for comparing the accumulated value with a preset value and controlling the selecting operation of the selector during the operation of the accumulator. The increasing accumulated value is used to address the waveform memory device to read out therefrom amplitude samples to form a desired musical tone wave form. The output of the waveform memory means is imparted with a volume envelope generated by an envelope waveform generator and then produced as a performance tone by a sound system.
TL;DR: In this article, the L 1 norm is used as an optimum solution criterion, therby allowing first motions to be included in the data set, and a mixed data set is warranted when only a small number of amplitude measurements are available.
Abstract: Amplitude data from direct and near-source reflected phases are inverted to obtain point-source moment tensors. The inversion scheme is computationally efficient, and the results can be interpreted without the uniqueness problems that plague many geophysical inversion schemes. This follows from the linear relationship between the moment tensor components and the recorded waveforms. The L1 norm is used as an optimum solution criterion, therby allowing first motions to be included in the data set. A mixed data set is warranted when only a small number of amplitude measurements are available. Displacement amplitudes at the recording stations are estimated by seismogram modeling in the case of the shallow earthquake and by the application of an optimum lag inverse filter in the case of the deep earthquake. The inverse filter is designed to remove the combined effects of the recording system and signal distortion owing to anelasticity.Results demonstrate that the inversion of body wave amplitude data for the unconstained moment tensor can yield essentially pure double couples.
TL;DR: In this article, a model of S- and P-wave N N → ππ amplitudes in the pseudophysical region has been con- structed from nucleon and isobar-exchange Born terms and models of π π rescattering consistent with empirical ρ phase shifts and chiral symmetry.
TL;DR: In this article, the authors studied the temporal evolution of small three-dimensional disturbances on viscous flows between parallel walls by using Fourier-Laplace transform (FLA) techniques.
Abstract: The temporal evolution of small three-dimensional disturbances on viscous flows between parallel walls is studied. The initial-value problem is formally solved by using Fourier–Laplace transform techniques. The streamwise velocity component is obtained as the solution of a forced problem. As a consequence of the three-dimensionality, a resonant response is possible, leading to algebraic growth for small times. It occurs when the eigenvalues of the Orr–Sommerfeld equation coincide with the eigenvalues of the homogeneous operator for the streamwise velocity component. The resonance has been investigated numerically for plane Couette flow. The phase speed of the resonant waves equals the average mean velocity. The wavenumber combination that leads to the largest amplitude corresponds to structures highly elongated in the streamwise direction. The maximum amplitude, and the time to reach this maximum, scale with the Reynolds number. The aspect ratio of the most rapidly growing wave increases with the Reynolds number, with its spanwise wavelength approaching a constant value of about 3 channel heights.
TL;DR: In this paper, a rainbow photometry technique was used to measure the phase and relative amplitude of steady-state, low-frequency (?100 Hz) deformations induced by a modulated 217.5 kHz acoustic wave.
Abstract: A new effect of acoustic radiation pressure was detected: the oscillating deformation of mm‐radius liquid drops (para‐xylene) acoustically levitated in a host liquid (water). A novel method is described for detecting μm amplitude deformations which utilized light scattered by the drop at the scattering angle normally associated with the rainbow. This rainbow photometry technique was used to measure the phase and relative amplitude of steady‐state, low‐frequency (?100 Hz) deformations induced by a modulated 217.5‐kHz acoustic wave. Some of the predictions in ’’Shape oscillation and static deformation of drops and bubbles driven by modulated radiation stresses—Theory’’ [J. Acoust. Soc. Am. 67, 15–26 (1980)] agreed with the measurements. Deformations driven by the radiation pressure could greatly exceed the first‐order displacement of the interface. The deformation amplitude varied as the square of the acoustic pressure, and phase had the expected dependence on the modulation frequency when data was normalized according to an experimentally determined damping parameter. The damping, however, was significantly larger than predicted for pure liquids. The interfacial tension inferred from the quadrupole resonance properties was 4% lower than static measurements. The apparatus was also used to levitate superheated drops and the technique may be useful for determining their interfacial tension.
TL;DR: For very small dissipation Pedlosky and Smith and Reilly as discussed by the authors showed that the limit cycle behavior of a weakly unstable finite-amplitude baroclinic wave with respect to the degree of dissipation satisfies the Feigenbaum relation (γn −γn−1)/(γn+1−γn)=4.669201.
Abstract: Numerical integrations of the amplitude equations governing the dynamics of a weakly unstable finite-amplitude baroclinic wave have revealed a new and unexpectedly complex dependence on the degree of dissipation. We have found for very small dissipation the simple limit cycle behavior noted earlier by Pedlosky (1971) and Smith and Reilly (1977). For slightly higher values of the dissipation further solution bifurcations reveal an ever-increasing family of periodic solutions whose periods are even multiples of the fundamental. The critical value of the dissipation parameter γ for which the nth cycle emerges, appears to satisfy the Feigenbaum (1978) relation (γn−γn−1)/(γn+1−γn)=4.669201. Above a limit point γ∞ the solutions are aperiodic and chaotic. However, at isolated “islands” within this chaotic regime we have again found periodic solutions. Although their phase plane trajectories differ from those found below γ∞, their periods are always multiples of half the fundamental. For higher γ, equili...
TL;DR: In this paper, the authors extended the quasisteady method to include the transient effect of the "spilled" leading edge vortex, thereby providing simple analytic means for prediction of dynamic stall characteristics at high frequency and large amplitudes.
Abstract: A previously developed quasisteady analytic method has been shown to give predictions that are in good agreement with experimental stall results as long as the oscillation amplitude and frequency are of moderate magnitudes. In the present paper, this quasisteady method is extended to include the transient effect of the "spilled" leading-edge vortex, thereby providing simple analytic means for prediction of dynamic stall characteristics at high frequency and large amplitudes. The veracity of the method is demonstrated by critical comparisons with the extensive experiments performed by Carr et al. c Ka / m
Patent•
21 Mar 1980
TL;DR: In this paper, a multi-channel memory system was proposed for monitoring and indicating changes in a scene from which electromagnetic radiation, such as visible light, emanates in a television system.
Abstract: A television system and method for monitoring and indicating changes in a scene from which electromagnetic radiation, such as visible light, emanates. A television system including a televison camera (10) scans the scene in known raster fashion in a series of image frames, producing an amplitude modulated video signal describing the energy intensity distribution of the scene. Clocking and gating circuitry (42, 44) triggered in synchronism with television camera synchronization signals defines a set of predetermined discrete spaced locations of the raster during each image frame and samples video signal amplitude at each of the defined locations. The same discrete locations a re sampled during each frame. Video selection circuitry (20) during a succession of sampling periods, inputs in real time a representation of each video amplitude sample to one of several storage channels (24, 26, 28) of a multi-channel memory system including a multi-channel counter. The video amplitude samples are allocated among the channels as a function of their amplitude values. The collection of stored amplitude samples in the multi-channel memory system thus constitutes a profile of the amplitude distribution of the video samples made during the frame. This first amplitude profile is then stored. The scanning, allocating and counting operation is repeated. Subsequently, comparison circuitry, (114, 116) in response to the development of a subsequent amplitude distribution profile, corresponding to a selected later frame, actuates an alarm (30) in response to the occurrence of a predetermined threshold difference between (1) the earlier and (2) a succession of later developed amplitude distribution profiles. Circuitry (132) is also provided for modifying characteristics of the threshold difference required to trigger the alarm. It has been found that even a single channel counter, responsive to video count samples in only a single amplitude range, can often provide enough information for a workable and inexpensive surveillance system.
TL;DR: In this article, a new technique for numerically solving the reduced wave equation on exterior domains is presented, which is basically a relaxation scheme which exploits the limiting amplitude principle, and a modified boundary condition at "infinity" is also given.
Abstract: A new technique for numerically solving the reduced wave equation on exterior domains is presented. The method is basically a relaxation scheme which exploits the limiting amplitude principle. A modified boundary condition at “infinity” is also given. The technique is tested on several model problems: the scattering of a plane wave off a metal cylinder, a metal strip, a Helmholtz resonator, an inhomogeneous cylinder (lens), and a nonlinear plasma column. The results are in good qualitative agreement with previously calculated values. In particular, the numerical solutions exhibit the correct refractive and diffractive effects at moderate frequencies.
TL;DR: In this paper, a theory of radio windows is given that uses a full wave integration of the governing differential equations in order to deal with the large gradient of electron concentration in a cold plasma.
TL;DR: In this paper, a numerical code based on Δ-analysis is applied to calculate the saturated amplitude of tearing modes dependent on the current density profile, and the measured dependence of the (2, 1) mode amplitude on electron density and plasma current can be absolutely predicted.
Abstract: A numerical code based on a Δ'-analysis is applied to calculate the saturated amplitude of tearing modes dependent on the current density profile. The only stellarator effect.included is the additional, shearless external rotational transform ι0 in the safety factor profile q(r). In this way, the stellarator field shifts the resonant q = 2 surface toward the outside, where the current density gradient is smaller, and stabilizes the (2, 1) mode as observed experimentally. Also the measured dependence of the (2, 1) mode amplitude on electron density and plasma current can be absolutely predicted by the calculations. – In addition to stabilizing the (2, 1) tearing mode, the current disruption is suppressed in Ohmically heated W VII-A discharges for ι0 0.15. The experimental findings, together with the calculated island widths, are compared with the predictions of a theoretical model proposed by several authors to explain the current disruption.
TL;DR: In this paper, the anomaly in the specific heat Cpx has been investigated by means of a constant heating rate method using range shrinking procedure and nonlinear-least-squares fits to the data.
Abstract: The anomaly in the specific heat Cpx has been investigated by means of a constant heating rate method. Accurate results could be obtained for ‖T‐Tc‖/Tc values as small as 7×10−6. From a range shrinking procedure and nonlinear‐least‐squares fits to the data we obtained α=α′=0.107±0.002, which is close to the renormalization group (RG) value αRG=0.110±0.008 for the Ising model for the dimensionality d=3. For the universal amplitude ratio A′/A of the diverging part of the specific heat above and below Tc, a value of 1.75±0.03 is obtained. This is also in agreement with theoretical predictions for the Ising model. Combining the amplitude of the correlation length with the critical amplitude of the specific heat allowed us to test two‐scale‐factor universality. For the universal constant X=Avξ30/kB in this system, a value of (1.9±0.4)×10−2 is obtained, which is in agreement with theory and with results for other fluid systems.
TL;DR: In this paper, the characteristics of amplitude vacillation, structural vacillation and geostrophic turbulence in two thermally driven rotating fluids with different viscosities are investigated and the data presented correspond to experiments performed at four points in dimensioniess-parameter space selected to illustrate the nature of these phenomena.
Abstract: The characteristics of amplitude vacillation, structural vacillation and geostrophic turbulence in two thermally driven rotating fluids with different viscosities are investigated. The data presented correspond to experiments performed at four points in dimensioniess-parameter space selected to illustrate the nature of these phenomena. They include synoptic temperature distributions, radial cross sections, time- averaged temperature variance spectra, and time and space variations of the eddy temperature variance as a function of wavenumber. Amplitude vacillation is characterized by periodic growth and decay of the temperature variance associated with a single azimuthal wavenumber and its immediate sidebands. Structural vacillation is characterized by almost periodic, modulated, radial redistributions of eddy temperature variance associated with a single azimuthal wavenumber and its higher harmonics, with little variation in the volume integrated eddy temperature variance. Geostrophic turbulence i...
TL;DR: In this paper, a fluctuating eddy viscosity model for Reynolds stress is proposed and the validity of this model is verified for all frequencies tested through comparisons between the calculations and measurements.
Abstract: A fluctuating eddy viscosity model for Reynolds stress is proposed. The validity of this model is verified for all frequencies tested through comparisons between the calculations and measurements. The analysis yields three properly-modified Strouhal numbers: the first of them is adequate to illustrate similarly the velocity distributions in turbulent region over a wide range of frequencies and the time-mean Reynolds numbers, the second is adequate in the vicinity of wall, the last is for the instantaneous friction factor. The following results are obtained: at low frequencies the amplitude of the wall shear stress is proportional to the amplitude of the velocity. At high frequencies it is proportional to both the velocity amplitude and the square root of the frequency. The predicted magnitude of the instantaneous friction factor exceeds that of steady state during accelerating flow and it is smaller than that during decelerating flow.
TL;DR: In this paper, a well-defined amplitude is introduced a priori, and the uniqueness for terms of any order is achieved, which offers not only more accurate approximations and numerical studies on convergence but also a whole series of new applications.
Abstract: * * The Landau-Stuart theory and its subsequent modifications suffer from some restrictions and from the nonuniqueness in determining higher-order terms of the amplitude expansions, which limit the range of applicability as well as the validity of the results. In the present paper, a well-defined amplitude is introduced a priori. In this way, uniqueness for terms of any order is achieved. Moreover, Watson's method is no longer restricted to almost neutral disturbances. This offers not only more accurate approximations and numerical studies on convergence but, as a consequence, a whole series of new applications. As a first example, the nonlinear equilibrium states of the plane Poiseuille flow are investigated. The numerical results are discussed in context with the author's solutions of the nonlinear equations and with special emphasis on the convergence of Landau's series. f
TL;DR: In this article, the authors investigate the nature of linear instabilities that can arise on eastward-flowing baroclinic currents similar to those found to serve as sites of strong eddy-mean flow interaction in certain mesoscale-resolution ocean circulation studies.
04 Jun 1980
TL;DR: In this paper, the angle and amplitude changes for acoustic waves refracted by a circular open jet shear layer were determined, and the generalized refraction theory was assessed experimentally for on axis and off axis acoustic source locations as source frequency varied from 1 kHz to 10 kHz and free stream Mach number varied from 0.1 to 0.4.
Abstract: The angle and amplitude changes for acoustic waves refracted by a circular open jet shear layer were determined. The generalized refraction theory was assessed experimentally for on axis and off axis acoustic source locations as source frequency varied from 1 kHz to 10 kHz and free stream Mach number varied from 0.1 to 0.4. Angle and amplitude changes across the shear layer show good agreement with theory. Experiments confirm that the refraction theory is independent of shear layer thickness, acoustic source frequency, and source type. A generalized theory is, thus, available for correcting far field noise data acquired in open jet test facilities. The effect of discrete tone scattering by the open jet turbulent shear layer was also studied. Scattering effects were investigated over the same Mach number range as frequency varied from 5 kHz to 15 kHz. Attenuation of discrete tone amplitude and tone broadening were measured as a function of acoustic source position and radiation angle. Scattering was found to be stronger at angles close to the open jet axis than at 90 deg, and becomes stronger as the acoustic source position shifts downstream. A scattering analysis provided an estimate of the onset of discrete tone scattering.
TL;DR: In this article, the horizontal-tovertical amplitude ratios of the long-period seismograms are reexamined to determine the shear wave velocity distributions at the Apollo 12, 14, 15, and 16 landing sites.
Abstract: The horizontal-to-vertical amplitude ratios of the long-period seismograms are reexamined to determine the shear wave velocity distributions at the Apollo 12, 14, 15, and 16 lunar landing sites. Average spectral ratios, computed from a number of impact signals, were compared with spectral ratios calculated for the fundamental mode Rayleigh waves in media consisting of homogeneous, isotropic, horizontal layers. The shear velocities of the best fitting models at the different sites resemble each other and differ from the average for all sites by not more than 20% except for the bottom layer at station 14. The shear velocities increase from 40 m/s at the surface to about 400 m/s at depths between 95 and 160 m at the various sites. Within this depth range the velocity-depth functions are well represented by two piecewise linear segments, although the presence of first-order discontinuities cannot be ruled out.
Patent•
24 Mar 1980TL;DR: An adaptive signal processing system for enhancing the signal-to-interfere characteristics on both receive and transmit using an in phase-quadrature correlator to control phase and amplitude adjust circuits located in the antenna signal paths is described in this article.
Abstract: An adaptive signal processing system for enhancing the signal-to-interfere characteristics on both receive and transmit using an in phase-quadrature correlator to control phase and amplitude adjust circuits located in the antenna signal paths. The amplitude adjustment provides amplitude balance control with variable delay lines between a quadrature hybrid and a sum-difference hybrid. The analog outputs of the correlator are digitized to control incrementally adjustable delay lines of the phase and amplitude circuits in binary steps.