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Showing papers on "Sine wave published in 1974"


Journal ArticleDOI
TL;DR: Spatial contrast measurements have been carried out with sine wave modulated fields, varying the aperture and the luminance and the modulation threshold turns out to depend upon the number of cycles in the stimulus for numbers of cycles below a critical number ofcycles.

198 citations


Journal ArticleDOI
TL;DR: In this article, the authors studied flagellar undulations that propel a micro-organism at a given speed while minimizing its expenditure of hydrodynamical energy, and showed that an apparent sliding motion along its instantaneous axis is fundamental to such motions, although an additional deformation is necessary to compensate for the presence of the head.
Abstract: This paper studies flagellar undulations that propel a micro-organism at a given speed while minimizing its expenditure of hydrodynamical energy. The study is in two basic parts. The first part is a qualitative inquiry into the general nature of undulations that are hydrodynamically optimal in the instantaneous sense. The results indicate that an apparent sliding of the entire flagellum along its instantaneous axis is fundamental to such motions, although an additional deformation is necessary to compensate for the presence of the organism's head. Periodic or semi-periodic undulations are clearly suggested, and must consist of travelling waves propagated in the direction opposite to propulsion.The second part of the paper is a quantitative inquiry as to the values of parameters that optimize given periodic wave shapes in the time-average sense. The trade-off between wave amplitude and the number of wavelengths is of particular interest. Results are obtained for small amplitude sinusoidal waves and finite amplitude sawtooth waves. For the latter, a single wavelength with amplitude roughly one-sixth of the wavelength is optimal. The significance of the twitching movements of the head is investigated. The results are consistent with the qualitative study and emphasize the need to inhibit such motions. The implications of the dependence of resistive-force coefficients upon wave shape are considered, and the physical significance of rotational pitching motions is assessed.

73 citations


Journal ArticleDOI
S. Rice1
TL;DR: The problem of computing the distributions of the envelope and instantaneous value of the sum of several sine waves plus Gaussian noise is reviewed and it is pointed out that the associated integrals can be efficiently evaluated by the trapezoidal rule except when the noise is small.
Abstract: The problem of computing the distributions of the envelope and instantaneous value of the sum of several sine waves plus Gaussian noise is reviewed. It is pointed out that the associated integrals can be efficiently evaluated by the trapezoidal rule except when the noise is small. Approximations which hold when the noise is small are given.

38 citations


Journal ArticleDOI
01 May 1974
TL;DR: In this article, several properties of solitary waves that were measured on an easily constructed transmission line of very modest size (50 sections ∼1-m length) were described, including their generation by a pulse or a sine wave, the recurrence phenomena, and the collision of two solitary waves.
Abstract: Several properties of solitary waves that were measured on an easily constructed transmission line of very modest size (50 sections ∼1-m length) are described. Among the properties observed are their generation by a pulse or a sine wave, the recurrence phenomena, and the collision of two solitary waves.

34 citations


Patent
13 Mar 1974
TL;DR: In this paper, a static inverter for converting a direct current input signal to an alternating current output signal, the inverter including a series of control loops to insure a stable, constant amplitude sine wave output.
Abstract: A static inverter for converting a direct current input signal to an alternating current output signal, the inverter including a series of control loops to insure a stable, constant amplitude sine wave output. The output sine wave is generated by comparing a high frequency triangle wave with a corrected reference sine wave, the output of the triangle wave comparator controlling the switching of conventional switching and filtering sections. The magnitude of the triangle wave is maintained proportional to the DC input signal, thereby maintaining the output sine wave relatively constant as the magnitude of the DC input signal varies. For control and regulation of the output, the AC signal present at the load is rectified, filtered and compared with a DC reference signal, the output of the DC comparator being used to proportionally adjust the amplitude of an AC reference sine wave. The amplitude adjusted reference sine wave is then compared with the output of the inverter to generate a signal representative of the distortion of the output, and this distortion signal is then summed with the amplitude adjusted reference sine wave to produce the corrected sine wave for application to the triangle wave comparator.

24 citations


Journal ArticleDOI
J. M. Terhune1
TL;DR: In this paper, the abilities of untrained adults to aim a pointer at a hidden sound source was measured using 1/3 octave noise bands centered at 1 and 8 kHz and a wide band noise, the localizational errors were 7°±7°, 6°±8° and 4°±4°.
Abstract: The abilities of untrained adults to aim a pointer at a hidden sound source was measured. The localization errors were 16°±13° and 13°±10° for 1 and 8 kHz sine waves. Using 1/3 octave noise bands centered at 1 and 8 kHz and a wide band noise, the localizational errors were 7°±7°, 6°±8° and 4°±4°. The nose band localization ability was significantly more acute than that for sine waves. This difference is attributed to prior experience with the acoustic clues. Noise bands provide time clues and are common in nature. Sine waves below about 1.4 kHz provide interaural phase clues and those above about 1.4 kHz provide interaural intensity clues. Sine waves are not common in nature, so the subjects had not had the opportunity to develop localizational abilities using these clues.

22 citations


Patent
18 Sep 1974
TL;DR: In this article, a frequency shift key modulator produces sine wave output signals of different frequencies for mark (1) and space (0) signal levels on an input "send data" lead including a counter which divides the frequency of an input oscillator by different denominators for the mark and space signals.
Abstract: A frequency shift key modulator producing sine wave output signals of different frequencies for mark (1) and space (0) signal levels on an input "send data" lead including a counter which divides the frequency of an input oscillator by different denominators for the mark and space signals and the output of which is synthesized to produce a stepped output approximating a sine wave and a final filter for smoothing the steps out of the output. In cases in which the mark and space output frequencies are approximately in the ratio of 1 to 2, a frequency divider is used for the mark output frequencies.

18 citations


Patent
Kyoichi Abe1
23 Dec 1974
TL;DR: In this article, a flexible membrane is undulated in a sine wave configuration by means of a series of linkages, one link of which is pinned to the underside of the membrane, and the combined movements of the various linkages cause the membrane to undulate as would water waves.
Abstract: An apparatus to generate a wave-like pattern of forces on a surface effect ship utilizes a flexible membrane which undulates in a water wave-like manner, the crests of the waves transferring forces to the surface effect ship. The membrane is undulated in its sine wave configuration by means of a series of linkages, one link of which is pinned to the underside of the membrane. That link is reciprocally actuated and the combined movements of the various linkages cause the membrane to undulate as would water waves. The main drive motor drives a primary shaft to which are connected a series of gear boxes which in turn drive secondary drive shafts. By controlling or varying the speed of the primary drive motor, the frequency of the generated waves may be varied. At each linkage station there is a crank and the connecting rod is adjustably connected to the crank. The amplitude of the waves can be varied as desired by adjustably positioning the connecting rod along the crank.

17 citations


Patent
13 Jun 1974
TL;DR: In this article, an alternating current electrical power generator of the rotating field type whose output frequency is independent of the rotational speed of the field was presented, where low frequency electrical power was produced by generating a high frequency polyphase voltage which is rectified alternately positive and negative and by simultaneously modulating the level of the high frequency voltage with a low frequency sine wave.
Abstract: An alternating current electrical power generator of the rotating field type whose output frequency is independent of the rotational speed of the field. Low frequency electrical power is produced by generating a high frequency polyphase voltage which is rectified alternately positive and negative and by simultaneously modulating the level of the high frequency voltage with a low frequency sine wave.

17 citations


Journal ArticleDOI
TL;DR: In this paper, a dc-ac converter with a magnetic circuit has been proposed, which can be converted to alternating sine wave voltage with an optional frequency and even if the load current is increased, the values of the output voltage and its frequency are constant over a wide range.
Abstract: The following is a brief description of the operation principle and the circuit configuration of a new dc-ac converter proposed by the authors. This device is constructed by a magnetic circuit of unusual shape and has a number of excellent characteristics in the operation. Therefore dc voltage can be converted to alternating sine wave voltage with an optional frequency, and even if the load current is increased, the values of the output voltage and its frequency are constant over a wide range.

15 citations


Journal ArticleDOI
TL;DR: In this paper, the wave factor WF is defined as the ratio of actual current drawn, to that which would be drawn by a resistive load with the same power consumption, and is derived for peak, rms and average input currents to full-wave rectifiers with capacitor input filters.
Abstract: Conventional, capacitor-input-filtered, full-wave rectifier power supplies draw much higher peak and rms line currents than the supply power drains would imply if the loads were resistive. Effective multiplication factors?termed wave factors?range from 5 to 15 for peak, and from 2 to 3 for rms, while remaining between 0.7 and 1 for average. Experimental data verify theoretical calculations for the wave factors involved. Ordinary clip-on and other conventional ammeters, measuring average but calibrated to read in rms for an equivalent sine wave, are thus unable to account for the difficulties sometimes encountered in the field. These include apparently undersized fuses, breakers and lines, plus severe clipping of the line voltage wave at the load. Solutions include use of auxiliary line inductors, plus wider recognition of the need for true rms metering with adequate crest factor capability in making all line current measurements. Implicacations for UPS (Uninterruptible Power Supply) manufacturers and users are also discussed. Wave factor WF is defined as the ratio of actual current drawn, to that which would be drawn by a resistive load with the same power consumption. Wave factors are derived for peak, rms and average input currents to full-wave rectifiers with capacitor input filters.

Patent
29 Apr 1974
TL;DR: In this paper, a method of measuring the refractive error of the eye using a digital computer is proposed, which uses a variable focus, variable orientation light pattern on the eye, detects the light pattern reflected from the retina to produce an analog signal as a function of the focus of the reflected pattern, and converts the analog signal to a digital signal stream fed to the computer.
Abstract: A method of measuring the refractive error of the eye uses a digital computer and directs a variable focus, variable orientation light pattern on the eye, detects the light pattern reflected from the retina to produce an analog signal as a function of the focus of the reflected pattern, and converts the analog signal to a digital signal stream fed to the computer The computer varies the focus of the pattern and the orientation of the pattern and selects and stores results from the digital signal stream It then fits a sine wave to the selected signal results, and calculates the refractive error from the sine wave


Journal ArticleDOI
TL;DR: Observations provide evidence that the sensory endings responsible for the transducer action do not obey linear transfer functions in sinusoidal stretching of the frog.
Abstract: The impulse response and the receptor potential 01 the isolated muscle spindle of the frog were recorded during sinusoidal stretching at frequencies from 0.1 c/s to 100 c/s. Attention was focused on the changes of the responses in the initial phase of stimulation before the steady state was reached. In the course of sine wave stimulation the impulse response of the spindle undergoes regular changes characterized by an increase in threshold and latency of the individual impulses, a decrease in phase lead and peak frequency and a reduction in number of spikes in each cycle. The changes are most pronounced during the first 2–5 cycles, and a steady state with a fixed impulse patterning is usually reached after 10–15 cycles. The receptor potential evoked by a sine wave stretch is distorted in comparison with the waveform of the stimulus in having a relatively faster rise and slower decay. With changes in frequency and amplitude of stimulation it undergoes characteristic alterations in phase lead and configuration. When superimposed upon a constant stretch or a linearly rising stretch, sinusoidal stimulation produces responses which increase in amplitude with the underlying stretch. These observations provide evidence that the sensory endings responsible for the transducer action do not obey linear transfer functions.

Patent
11 Feb 1974
TL;DR: In this paper, a sine wave oscillator feeds a square wave generator, and the generator produces 50 percent duty cycle pulses having leading and trailing edges coinciding with alternate edges of the square wave.
Abstract: A sine wave oscillator feeds a square wave generator. Pulse generator means produces 50 percent duty cycle pulses having leading and trailing edges coinciding with alternate edges of the square wave and 25 percent duty cycle pulses having leading and trailing edges coinciding with successive edges of the square wave. Gate generating means produces one series of gating pulses coinciding with the leading or trailing edges of the 50 percent duty cycle pulses and a second series coinciding with edges of the 25 percent duty cycle pulses lying halfway between the edges of the 50 percent duty cycle pulses or halfway between successive pulses. The 50 percent duty cycle pulses drive test coil means whose output is supplied to an amplifier tuned to the PRF thereof, and then to a pair of quadrature detectors supplied with respective series of gating pulses.

Journal ArticleDOI
TL;DR: In this article, a general expression for the probability density function of the output of a cross correlator, the inputs of which are assumed to consist of clipped sine waves of similar frequency plus uncorrelated, stationary Gaussian noise, was derived.
Abstract: A general expression is derived for the probability density function of the output of a cross correlator, the inputs of which are assumed to consist of clipped sine waves of similar frequency plus uncorrelated, stationary Gaussian noise. The correlator output is shown to be a piecewise linear function of the random phase difference between the two input processes; hence, the density function for the correlator output is obtained by a relatively simple transformationfrom the probability density function of the random phase difference.

Patent
24 Jun 1974
TL;DR: In this article, a system for determining the phase displacement of vibration data signals relative to tachometer point signals by synthesizing a sine wave signal having the amplitude of the vibration signals is presented.
Abstract: A system for determining the phase displacement of vibration data signals relative to tachometer point signals by synthesizing a sine wave signal having the amplitude of the vibration data signals, shifting the phase of the synthesized sine wave signal to null out the vibration data signals and determining the phase and amplitude of the synthesized sine wave signal relative to the tachometer point signals.

Journal ArticleDOI
TL;DR: In this paper, a unified treatment of many problems in digital pulse recording is presented, characterized by a reciprocal-space transfer function, which may be abstracted from published studies of sine wave recording.
Abstract: In this paper we present a unified treatment of many problems in digital pulse recording. The physics appropriate to each problem is characterized by a reciprocal-space transfer function, which may be abstracted from published studies of sine wave recording. Over twenty-five transfer functions are given in appendices. Given the transfer functions, an inverse Fourier transformation completes each problem. The fields, fluxes, and output voltage due to an arctangent magnetization profile in a tape of unit permeability are derived. A closely related case, that of a linear ramp magnetization, is treated briefly. A step function magnetization is considered for a tape of nonunit permeability in which, dependent upon the boundary conditions, demagnetization and remagnetization occur. Extensions of the theory of multitransition waveforms are undertaken, yielding the spectra of both regular and random sequences.

Patent
19 Aug 1974
TL;DR: In this article, a symmetrical non-linear network for use in a function generator in which one or other of a pair of transistors is brought progressively into conduction by a nonlinear network, so as to present a low dynamic resistance between the terminals.
Abstract: A symmetrical non-linear network for use in a function generator in which one or other of a pair of transistors is brought progressively into conduction by a non-linear network, so as to present a low dynamic resistance between the terminals. The non-linear network preferably includes a pair of diodes having a lower turn on voltage than that of the associated transistors, for example Schottky diodes with silicon transistors. The invention also provides a function generator incorporating the above non-linear network for converting square waves to sine waves in which the amplitude of the input signal to the network is controlled automatically.

Journal ArticleDOI
TL;DR: In this paper, the authors deal with the response of a stratified cold plasma to an infinite plane electromagnetic wave incident vertically on the ionization by utilizing a multiple-scattering technique, by summing a large number of scalar functions described as first scatter, second scatter, etc.
Abstract: This paper deals with the response of a stratified cold plasma to an infinite plane electromagnetic wave incident vertically on the ionization. The transient response is found by utilizing a multiple-scattering technique, by summing a large number of scalar functions described as first scatter, second scatter, etc. A generalized formula is used for finding the nth scattered field in terms of the (n-1)th scattered field. Specifically two cases are considered: the generalized response of a half-space of uniform electron density to any incident wave expressible in a Maclaurin series, and the response of an infinite region whose electron density increases exponentially with height to an incident step-modulated sine wave.

Journal ArticleDOI
TL;DR: At low spatial frequencies (less than 2 c/deg) the sensitivity of the visual system for sine waves increases with frequency, while that for the noise bands decreases with spatial frequency.

Journal ArticleDOI
TL;DR: In this article, an electronic system has been developed which generates two phase and harmonically related signals for use in gas laser frequency stabilization, one waveform is a square wave and the other is a sine wave of variable phase, at one third of the square wave frequency.
Abstract: An electronic system has been developed which generates two phase and harmonically related signals for use in gas laser frequency stabilization. One waveform is a square wave and the other a sine wave of variable phase, at one third of the square wave frequency. The sine wave has a harmonic content of less than 0.1% at the square wave frequency.

Journal ArticleDOI
TL;DR: A combination of deformable flow probes of negligible lateral dimensions with an electronic circuit capable of providing a prolonged plateau of dB/dt = 0 and of sampling the flow signal at the end of this interval permits electromagnetic measurement of blood flow with a reliable zero base line secured by switching off the magnet.
Abstract: A combination of deformable flow probes of negligible lateral dimensions with an electronic circuit capable of providing a prolonged plateau of dB/dt = 0 and of sampling the flow signal at the end of this interval permits electromagnetic measurement of blood flow with a reliable zero base line secured by switching off the magnet. An extracorporeal magnet provides the magnetic field. The flow transducer is introduced into the vascular system percutaneously through a standard angiographic catheter by conventional technique. The idea of the current generator can be described as “principle of interrupted resonance.” The current wave form can be described as a sequence of disconnected bisected sine waves joined at the apices by horizontal current plateaus where di/dt is strictly zero.

Patent
Harold Garth Nash1
02 Jan 1974
TL;DR: In this article, a two-eight tone encoder utilizing digital techniques to synthesize the dual tones of a touch-tone telephone operator system is provided, which includes a counter which is programmable by the row input signals.
Abstract: A two of eight tone encoder utilizing digital techniques to synthesize the dual tones of a Touch Tone telephone operator system is provided. One of sixteen switches from the telephone keyboard selects one of four desired row tones and one of four desired column tones. The two of eight encoder circuit includes, for the row encoding section, a counter which is programmable by the row input signals. The counter output drives a plurality of exclusive OR gates and a one of eight decoder which switches one of eight resistors into a resistive divider network. The exclusive OR gates and the one of eight decoder cooperate to perform an up-down counting function. The eight resistors are chosen in value so that a synthesized stepped sine wave is generated at the output of the resistive divider network, the synthesized stepped sine wave corresponding to the desired selected row frequency. Similar circuitry generates a stepped sine wave corresponding to the desired selected column frequency. The two stepped sine waves are filtered, if desired, and provided as inputs to a summation amplifier, the output of which produces the desired tone having the frequency components for both the selected row input and the selected column input.

Patent
17 Oct 1974
TL;DR: In this paper, a voltage controlled sine wave oscillator is described in which the frequency of the output signal is a linear function of the amplitude of an input control signal. But the oscillator of the invention in the embodiment to be described herein is solid state, and it makes use of operational integrators, analog multipliers, and associated circuitry to generate the outputs.
Abstract: A voltage controlled sine wave oscillator is provided in which the frequency of the output signal is a linear function of the amplitude of an input control signal. The output signal may be of constant amplitude with changes in frequency, or its amplitude may be a linear function of its frequency. Two-phase quadrature output signals may be provided for multi-phase applications. The oscillator of the invention in the embodiment to be described herein is solid state, and it makes use of operational integrators, analog multipliers, and associated circuitry to generate the outputs.

Patent
05 Jun 1974
TL;DR: A generator for controlling a transducer by means of sinusoidal wave trains is constituted by the association in series of a generator for producing wave trains formed by a whole number of half-cycles of periodic signals and of a filter which is tuned to the frequency of the periodic signals.
Abstract: A generator for controlling a transducer by means of sinusoidal wave trains is constituted by the association in series of a generator for producing wave trains formed by a whole number of half-cycles of periodic signals and of a filter which is tuned to the frequency of the periodic signals.

Journal ArticleDOI
TL;DR: In this article, the generalized cross transfer functions for the system have been evaluated and applied to investigate the images of sine wave objects and the dependence of the spatial frequency response upon the coherence parameter and the obscuration ratio of the aperture has been discussed.
Abstract: The imagery of extended objects by a system having aberration free annular aperture and employing partially coherent illumination has been investigated. The generalized cross transfer functions for the system have been evaluated and applied to investigate the images of sine wave objects. The dependence of the spatial frequency response upon the coherence parameter and the obscuration ratio of the aperture has been discussed.