Showing papers on "Sine wave published in 1989"

Three stages and two systems of visual processing.

Abstract: Three stages of visual processing determine how internal noise appears to an external observer: light adaptation, contrast gain control and a postsensory/decision stage. Dark noise occurs prior to adaptation, determines dark-adapted absolute thresholds and mimics stationary external noise. Sensory noise occurs after dark adaptation, determines contrast thresholds for sine gratings and similar stimuli, and mimics external noise that increases with mean luminance. Postsensory noise incorporates perceptual, decision and mnemonic processes. It occurs after contrast-gain control and mimics external noise that increases with stimulus contrast (i.e., multiplicative noise). Dark noise and sensory noise are frequency specific and primarily affect weak signals. Only postsensory noise significantly affects the discriminability of strong signals masked by stimulus noise; postsensory noise has constant power over a wide spatial frequency range in which sensory noise varies enormously. Two parallel perceptual regimes jointly serve human object recognition and motion perception: a first-order linear (Fourier) regime that computes relations directly from stimulus luminance, and a second-order nonlinear (nonFourier) rectifying regime that uses the absolute value (or power) of stimulus contrast. When objects or movements are defined by high spatial frequencies (i.e., texture carrier frequencies whose wavelengths are small compared to the object size), the responses of high-frequency receptors are demodulated by rectification to facilitate discrimination at the higher processing levels. Rectification sacrifices the statistical efficiency (noise resistance) of the first-order regime for efficiency of neural connectivity and computation.

Rugate filter sidelobe suppression using quintic and rugated quintic matching layers.

Abstract: Sine wave rugate index profiles may be superimposed on a slowly varying average index in such a way as to reduce sidelobes over broad spectral regions and at the same time maintain the strength of the stopband reflectance.

Energy Absorption Behavior of Graphite Epoxy Composite Sine Webs

Abstract: The static energy absorption behavior of graphite epoxy composite cor rugated (sine wave) webs loaded in axial compression is reported in this paper. Tests have been conducted to study the effects ...

Fluorescent dimming ballast utilizing a resonant sine wave power converter

Abstract: In a method or combination, a DC voltage supply, a converter including a series or a parallel resonant circuit (LR, CR, TR) for converting the DC voltage to a sinusoidal current, and a load (T1, T2) including at least one fluorescent lamp responsive to the sinusoidal current to effect excitation of the lamp.

Analysis of Natural Waves by Local Approximations

Abstract: Local approximations are recommended as a tool for the analysis of natural water waves. The particular class of local approximations described is based on local fitting of a sine curve, which leads naturally to the definition of locally defined frequencies. As a specific application, two methods are outlined for estimating surface elevations of large (nonlinear) waves from subsurface pressures. One of the methods is simple enough to be condensed into a single formula that expresses the surface elevation in terms of three pressure readings. Yet, its accuracy is better than that of the traditional spectral transfer method. Guidelines are presented for the use of the methods in connection with real (noisy) data.

Phase coherence in speech reconstruction for enhancement and coding applications

Abstract: It has been shown that an analysis-synthesis system based on a sinusoidal representation leads to synthetic speech that is essentially perceptually indistinguishable from the original. A change in speech quality has been observed, however, when the phase relation of the sine waves is altered. This occurs in practice when sine waves are processed for speech enhancement and for speech coding. A description is given of a zero-phase sinusoidal analysis-synthesis system which generates natural-sounding speech without the requirement of vocal tract phase. The method provides a basis for improving sound quality by providing different levels of phase coherence in speech reconstruction for time-scale modification, for a baseline system for coding, and for reducing the peak-to-RMS ratio by dispersion. >

Method of and apparatus for reducing energy consumption

Abstract: The proposed invention is an energy saving load control device primarily intended for inductive loads (i.e., fluorescent lighting, motors, etc.) operating from an alternating current (AC) source. The proposed device switches the load voltage off at arbitrary positions in the sine wave and simultaneously provides a commutating path for any inductive current. By switching the load voltage on and off and providing a commutating current path reduced energy consumption is realized.

A switched capacitor, inductorless DC to AC voltage step-up power converter

Abstract: A technique for efficiently producing low-harmonic, 60 Hz sinusoidal 110 V AC from a 24 V DC source without inductors or transformers is presented. The novel circuit topology allows the same power MOSFETs that sequentially charge a bank of capacitors to synthesize the staircase sine wave approximation. A Fourier analysis of the effects of MOSFET on-resistance and switching time on a 1 kW prototype is presented. >

Microprocessor-based sinusoidal waveform synthesis using Walsh and related orthogonal functions

Abstract: A method is described of eliminating harmonics in a pulsewidth-modulated waveform using Walsh and related functions that substitute linear algebraic equations for the nonlinear equations required in Fourier-series harmonic elimination. A microprocessor can then be used to calculate the firing angles to cancel the unwanted harmonics. In an extension of the method, it is shown that a sine wave can be synthesized from a fixed-voltage DC supply by using a reasonable number of power electronic switches. >

Image recording apparatus.

Abstract: PURPOSE:To prevent the positional displacement of colors on an image even if the speed of a transfer belt changes by making the moving distance of a recording material which corresponds to the distance while a belt driving roller makes one rotation an integral multiple of the distance of recorded images CONSTITUTION:The moving distance of a recording paper which corresponds to the distance while a belt driving roller 102 makes one rotation is set to be equal to the distance 3H between a BK head 1BK and a C head 1C In other words, when the diameter of the belt driving roller 102 is (d) and the thickness of the belt is (t), the moving distance is set so as to satisfy the relationship pi(d+2t)=3H In this case, if the driving roller is processed or assembled eccentrically, the moving speed of the recording paper on the transfer belt 102 is not constant, and the speed of the belt changes in a sine curve Since the phase angle of the eccentric driving roller at the starting position of printing by black and cyan is always constant although the printing position of images is changed in the sine curve, the phase of the sine wave of the printed image is always constant as well Therefore, the shift of BK and cyan colors is actually never brought about on the image

Instantaneous feedback control of a single-phase PWM inverter with nonlinear loads by sine wave tracking

Abstract: The authors propose a novel method for the instantaneous digital control of a PWM (pulse-width modulated) inverter used in an uninterruptible power supply. The output voltage is compared to a sinusoidal reference at each sampling instant to compute in real time through a digital controller the pulse width of the same interval. The closed-loop digital feedback eliminates the steady-state error of the output voltage with a very short computation time. This strategy is verified through computer simulations and provides a very fast compensation of disturbances caused by nonlinear loads, such as rectifiers and triac loads, with low total harmonic distortion and fundamental control. >

Three phase sine wave voltage source inverter using the soft switched resonant poles

Abstract: A zero-voltage-switching-based three-phase voltage source inverter is presented. The soft switched resonant pole, which is obtained by generalizing the conventional pseudo-resonant pole, is presented, and suitable control and modeling methods are described. The three-phase resonant pole inverter is easily obtained by connecting three resonant poles to a voltage source in parallel, and it can be operated on a higher power level than the conventional resonant DC-link inverters with the same ratings, since the device stresses are lower. It exhibits high-quality spectral performance close to the sinusoidal waveform, due to the filtering action of LC elements. Analysis and simulation results are shown to verify the operating principle of the proposed three-phase resonant pole inverter. The superiority of the proposed inverter to the PWM (pulse-width modulation) inverter is demonstrated. >

Effect of sampling jitter on some sine wave measurements

Abstract: The effects of sampling jitter on the measurement of amplitude and phase of a sinusoidal signal have been investigated. The parameters are determined by the fast Fourier transform (FFT) algorithm, which processes the samples following data acquisition. Results are expressed in terms of the mean values and variances of the measured parameters. Computer simulation results, based on Gaussian jitter show the changes of amplitude and phase standard deviations versus the changes of jitter standard deviation and signal amplitude for different numbers of samples, N. It is shown that amplitude and phase standard deviations are inversely proportional to square root N, and proportional to sigma /sub R/, the standard deviation of phase noise (jitter). This dependence on sigma /sub R/ means proportionality to both signal frequency and time jitter standard deviation. >

Rugate filter incorporating parallel and series addition

Abstract: A rugate type thin film optical interference filter is disclosed. Rugate filters are gradient-index optical filters in which the index of refraction of the film varies sinusoidally with thickness. Gradient-index filters vary the index of refraction continuously with thickness, instead of discontinuously as in, for example, quarter-wave stacks of alternating discrete layers of high and low refractive index. Rugate filters are generally used as narrow bandwidth blocking, or rejection, filters in which the specific wavelength of light reflected, or blocked, is directly proportional to the period of a simple sine wave that describes the refractive index profile of the film. Multiple-line rejection filters, in which more than one wavelength, or line, is reflected, are made by superimposing individual sine waves in parallel. The present invention provides a more easily made rugate filter by reducing the maximum required peak-to-peak refractive index modulation within the film. This is accomplished by having the sine wave for rejecting the longest wavelength line extend through the refractive index profile for the entire film thickness and connecting the sine waves for rejecting shorter wavelength lines in series and superimposing them with the sine wave for rejecting the longest wavelength line. It also enables the fabrication of rugate filters having more individual reflectance bands of similar bandwidth than would otherwise be possible with a given pair of materials.

Domain conversion under high frequency excitation in inductive thin film heads

Abstract: A magnetooptic microscope was used to observe the time-averaged magnetization distribution in an inductive thin-film head excited by continuous sine waves. Domain activity in yokes driven with sinusoidal currents (1 to 20 MHz) was observed using the Kerr effect at video frame rates (0 to 30 Hz). Thus, the average location and shape of domains in the top yoke of the head could be recorded. It is shown that the domain pattern generally undergoes significant changes in a slow, repeatable evolution. Some changes lead to abrupt conversions of domain states. Although specific behavior varies from head to head, these conversions follow measurable curves having a common trend in the amplitude versus frequency space. Previous work on analysis of head response has not considered this type of dynamic response, although it appears to be common to many magnetic system. In addition to possible response at the excitation frequency, the wall network can also undergo large changes with a time scale much longer than the excitation period. Three possible mechanisms driving the domain conversions are outlined. >

Parallel operating system for alternate current output converters

Abstract: A parallel operating system for A.C. output converters of high frequency PWM inverters of an instantaneous current valve control type is provided with a current minor loop for controlling the instantaneous value of the output current. The current of each inverter minor loop is adapted to be supplied with a command value from a voltage major loop and a command value corresponding to the load current to be borne by each converter derived from the load current, as the command value for the current to be output by the converter for maintaining the output voltage at a sine wave.

Repetitive waveform high frequency, high precision digitizer

Abstract: A digitizing technique for measuring high-speed phenomena with very high precision is described. A commercially available waveform digitizer using this method is shown to exhibit settling times of less than 5 ns to 0.1% and less than 10 ns to 0.01% after a voltage transition. Also, RMS measurements of sine waves up to 100 MHz show errors on the order of that obtained using a thermal transfer standard. >

A floating-window algorithm for detecting certain power line faults that disrupt sensitive electronic loads

Abstract: A floating-window algorithm is described that performs a triggering function that detects changes in the voltage waveform which can disrupt sensitive electronic loads. The proposed algorithm is an extension of a digital equivalent of G.W.Allen's (see IEEE Trans. Power Appl. Syst., vol. PAS-90, p.2604-9, May 1971) concept of an ideal-template-matching triggering mechanism, in which the digitized samples of a voltage waveform would be compared with the digitized values of an ideal waveform (in this case, the ideal sine wave). The proposed floating-window trigger mechanism uses each cycle of the AC waveform as a template for the succeeding cycle. Consequently, it triggers on a change in the shape of the voltage wave form. The proposed triggering function can be used to capture digitally sampled power line disturbances so their cause can be identified and corrected. >

Method of improving magnetic devices by applying AC or pulsed current

Abstract: A method of improving the magnetic properties of a ferromagnetic materials is disclosed. The method comprises a step of providing a specimen made of Fe, Ni or Co based amorphous alloys in a magnetizing field and a second step of applying an AC current or pulsed current on the specimen to improve its soft magnetic properties. The applied AC current has a frequency of 50 to 50K Hz, a wave form of either sine wave, triangular wave or square wave, and a current density of 10 to 500 A/cm2. The magnetic properties of the ferromagnetic materials are improved by a coercivity ratio less than 0.5, a magnetic induction ratio greater than 1 and a core loss ratio less than 0.3.

Quadrature amplitude modulation with line synchronization pulse for video telephone

Abstract: The present invention assigns amplitudes of sine wave cycles in a data packet on I and Q channels of a QAM signal to color, gray or luminance values. Overlapping sine wave cycles on the I and Q channels in the data packet are assigned to the same or neighboring pixels. A synchronizing signal is sent at the beginning of each transmission of a packet. The synchronizing signal is a plurality of cycles at a maximum amplitude on the I and Q channels. The synchronizing signal serves two functions simultaneously. First, it is used to indicate the beginning of a new packet. Second, the phase of the synchronizing signal is used to initialize the demodulator phase detecting circuitry.

A theorem in thermoelasticity and its application to linear stability

Abstract: Equations are written down governing the propagation of plane sinusoidal waves of small amplitude through a homogeneously prestrained equilibrium state of a materially homogeneous thermoelastic body of arbitrary elastic and thermal symmetry. The symmetric isothermal and isentropic acoustic tensors are defined in the usual way and it is assumed that the former is positive definite, so that it has three real and positive eigenvalues. It is shown, under the usual assumption that the specific heat at constant deformation is positive, that the three real and positive eigenvalues of the isentropic acoustic tensor are interlaced with those of the isothermal acoustic tensor, the smallest eigenvalue belonging to the isothermal and the largest to the isentropic acoustic tensor. Under the additional assumption that the symmetrized thermal conductivity tensor is positive definite, it is further shown that this result on the interlacing of the eigenvalues is sufficient to guarantee, for all positive values of the frequency of the sinusoidal waves, that the material is linearly stable in the sense that sinusoidal waves may not increase without bound in the direction of propagation. In the final section, the wide diversity in behaviour of the complex squared wave speed as a function of frequency is illustrated graphically. The stability result is extended to negative frequencies as these would be required in any Fourier synthesis of the sinusoidal wave solutions. A connection with Whitham's wave hierarchy approach is mentioned.

Sequential chirp modulation-type spread spectrum communication system

Abstract: A sequential chirp modulation-type spread spectrum communication system is disclosed relating to the FH-type which realizes fine transmission quality at low cost. It comprises at least primary and secondary digital sine wave generators of a program controlled-type mounted respectively on a transmitter of a transmitting side and a receiver of a receiving side. The primary sine wave generator generates a sine wave having a frequency which changes almost continuously and Pseudo-Random in the specified range of frequency according to the program. The primary digital sine wave generator also transmits the sine wave from the transmitting side after modulating the sine wave with the signals which should be transmitted. The secondary digital sine wave generator generates a sine wave having a frequency in which the specified frequency is a constant distance from the receiving signal frequency and receiving the receiving signal after demodulating.

Subgrouping Reduces Complexity and Speeds Up Learning in Recurrent Networks

Abstract: Recurrent nets are more powerful than feedforward nets because they allow simulation of dynamical systems. Everything from sine wave generators through computers to the brain are potential candidates, but to use recurrent nets to emulate dynamical systems we need learning algorithms to program them. Here I describe a new twist on an old algorithm for recurrent nets and compare it to its predecessors.

Electronic musical instrument with improved capability for simulating an actual musical instrument

Abstract: A musical sound waveform generator includes a carrier signal generating unit, a modulation signal generating unit, a mixing controlling unit and a waveform outputting unit. The characteristics of the carrier signal from the carrier signal generating unit are determined such that the musical sound waveform generated by the waveform outputting unit is a sine wave or a cosine wave with a single frequency, where the mixing ratio of the modulation signal is made 0 by the mixing controlling unit. Therefore, the mixing controlling unit presets the mixing ratio of the modulation signal to be 0, making it possible to generate a musical sound waveform which is only a sine wave or a cosine wave of a single frequency. During the performance, the mixing ratio can, for example, be determined at a high value immediately after the start of sound generation and thereafter reduced to near 0 with time. Thereby, the frequency characteristics of the musical sound waveform can be controlled such that the musical sound waveform is changed from one having a lot of higher harmonics to one having only a single sine wave component or a single cosine wave component.

Detection and estimation using the third moment matrix

Abstract: The third moment matrix R/sub 3/ is proposed as a tool for use in the detection and estimation of phase-coupled sine waves. The advantages of such an approach are that the structure of R/sub 3/ can be exploited by means of the singular value decomposition (SVD) to estimate directly the number of coupled sine waves and their frequencies. After a brief introduction to the bispectrum and the phase coupling problem, the following key results are presented: (1) The rank of R/sub 3/ is (asymptotically) equal to the number of coupled sine waves. (2) A pseudobispectrum can be generated using a MUSIC-like algorithm with vectors orthogonal to the (column) signal subspace. (3) The coupled frequencies can be directly estimated from the (row) signal subspace using techniques such as Root-MUSIC or ESPRIT. Examples of simulations using this approach are given. >

Method and apparatus for detecting positions and/or speed of a moving body using two phase signals

Abstract: Sine wave signals generated from a position detector are used as analog values to detect a fine position of a rotating or moving body, a rise or fall edge of the sine wave signal is used to detect a coarse position of the rotating or moving body, and the position or speed of the rotating or moving body is detected based on a signal indicative of the detected coarse position when the rotating or moving body is at high speed and based on a signal indicative of the detected fine position when the rotating or moving body is at low speed to thereby provide optimal control from high speed to low speed. Especially at extremely low driving, speed detection with superhigh resolution is effected using the analog value to decrease an uneven rotation of the rotating body.

Position or speed sensing apparatus

Abstract: Sine wave signals generated from a position detector (3) are used as analog values to detect a fine position of a rotating or moving body, a rise or fall edge of the sine wave signal is used to detect a coarse position of the rotating or moving body, and the position or speed of the rotating or moving body is detected based on a signal indicative of the detected coarse position when the rotating or moving body is at high speed and based on a signal indicative of the detected fine position when the rotating or moving body is at low speed to thereby optimal control from high speed to low speed. Especially at extremely low driving, speed detection with superhigh resolution is effected using the analog value to decrease an uneven rotation of the rotating body.

Low cost three phase energy economizer

Abstract: An energy economizing AC power control system for energizing the stator windings of a three phase induction motor comprises an AC generator connected to the motor rotor shaft for generating an AC signal that is frequency modulated in response to load induced speed variations of the rotor, a variable resistance whose magnitude is responsive to the frequency modulated signal, an AC power proportioning switch which produces a single phase output consisting of pulses whose widths vary with variations in the magnitude of the variable resistance, a single phase-to-three phase converter coupled to the output of the proportioning switch for producing three control signals that occur respectively at the frequency of and during each voltage phase alternation of a three phase sine wave power supply, and three solid state switches that are respectively controlled by said control signals for controlling the time duration that each alternation of the three phase power supply is coupled via an associated one of the solid state switches to an associated one of the motor stator windings.

Sine wave oscillator

Abstract: PURPOSE:To suppress the change of an oscillatory frequency for the change of the coefficient of a multiplier to a small value in case where the oscillatory frequency is remarkably lower than a sampling frequency and to set an arbitrary frequency with a few number of hardware, by providing third and fourth adders and the multiplier in a sine wave oscillator using a second-order circulation type filter. CONSTITUTION:The third and fourth adders 24 and 25 and the multiplier 28 are provided. Oscillation is started by adding a unit impulse string delta(n) on an input terminal 20. Since a delay apparatus 26 delays the output of the multiplier 28 by the time of the coefficient Z after starting the oscillation, delayed output is added on the output of the multiplier 28 by the adder 24, and after an added result is delayed again by the delay apparatus 26, it is supplied to multiplier 29 and 30 sides. Similarly, a delay apparatus 27 also delays the output of the multiplier 29, and the delayed output is added on the output of the multiplier 29 by the adder 25, and after the added result is delayed again by the delay apparatus 27, it is supplied to the multiplier 31 side. When an oscillatory state is stabilized, the sine wave oscillatory waveform of an output sample string y(n) is outputted from an output terminal 21.