Sine wave

About: Sine wave is a research topic. Over the lifetime, 12183 publications have been published within this topic receiving 93013 citations. The topic is also known as: sinusoid.

System and method for determining harmonic contributions from non-linear loads

Abstract: Neural networks have been known to be good function approximators. They are particularly effective in dealing with non-linear relationships between parameters. This feature is exploited in this paper to propose a new method for the problem of measuring harmonic current injected into a power system network by a non-linear load without disconnecting the load from the network. This work is particularly useful in determining whether the utility or the customer side has a higher contribution to harmonic pollution in a network. Hence this method would be helpful in settling utility-customer disputes over who is responsible for harmonic distortions. The main advantage of this method is that only waveforms of voltages and currents have to be measured. A neural network structure with memory is used to identify or learn the non-linear load admittance of a load. Once it has learned the admittance, the neural network predicts the true harmonic current of the load when supplied with a clean sine wave. This method is applicable for both single and three phase loads. This could be fabricated into a commercial instrument that could be installed in substations of large customer loads, or used as a hand-held clip on instrument.

Multiple Reflections in a Free Piezoelectric Plate

Abstract: This paper treats the development of thickness‐dilational acoustic transients in mechanically free piezoelectric plates. In particular, the effects of external electrical loading circuitry are studied. These effects are most pronounced under short‐circuit conditions. In a short‐circuited voltage‐step excited plate, stress and current responses consist initially of alternating exponential pulses. These, in an unexpected manner, decay to a sine wave accompanied by a sequence of sharp spikes. The sinusoidal and the spike system are characterized by different periods. A small signal theory for lossless materials is presented and supported by experiments with plates made of quartz and lead titanate‐zirconate. The arrangement is useful for dynamic measurement of piezoelectric constants.

Pulse width modulated inverter system for driving single phase a-c induction motor at a constant voltage/frequency ratio

Abstract: A sinusoidally weighted pulse width modulated switching signal may be developed, for operating an inverter to apply sinusoidal voltage to a single phase a-c induction motor, by comparing a triangular voltage waveform of fixed frequency with a variable frequency sine wave voltage, the switching signal varying between its high and low states whenever the triangular waveform and modulating sine wave intercept one another. A constant ratio of the amplitude of the sinusoidal motor voltage relative to the voltage's frequency, and thus motor speed, may be obtained simply by translating the sinusoidal modulating waveform through a high pass filter before it is compared with the triangular wave. By setting the filter cut-off frequency above the operating frequency range (preferably from about 12 to 60 hertz) of the sine wave generator, the sine wave voltage will be attenuated by the filter in an amount inversely proportional to the sine wave frequency. In this way, the amplitude of the sine wave will vary in step with, and directly proportional to, frequency changes to achieve a constant motor voltage/frequency ratio.

Electronic alarm for avoiding collision with animals in a non-destructive manner

Abstract: An electronic alarm is disclosed for use in a moving vehicle which generates ultrasonic sound for preventing animals from moving into the path of the vehicle. The device includes a simplified driver circuit for generating electrical impulses in the form of square waves having constant peak-to-peak voltages. The driver generates the square waves with periodic, sequentially increasing wave frequencies followed by sequentially decreasing wave frequencies. A coupling transformer converts the square waves into electrical sine wave voltages having high peak-to-peak voltages to cause a piezo-electric transducer to emit intense, ultrasonic sounds of periodically increasing frequencies followed by periodically decreasing frequencies simulating the warble effect of a siren without excessive heating and premature failure of the transducer. The ultrasonic warble effect confuses the animal to prevent inadvertent movement by the animal into the oncoming vehicle's path without injury to the animal.

Binaural coherence edge pitch

Abstract: The binaural coherence edge pitch (BICEP) is a dichotic broadband noise pitch effect similar to the binaural edge pitch. The noise is made by summing sine waves with equal amplitudes and random phases. The interaural phase angle is a constant for sine wave components with frequencies below a chosen frequency, and it is a random variable for components with frequencies above that frequency. The chosen frequency is a coherence edge because the signals to the two ears are mutually coherent within any band of frequencies below the edge and they are mutually incoherent in any band above the edge. Sine tone pitch matching experiments show that the BICEP exists for coherence edge frequencies between 300 and 1000 Hz and that it is always matched by a frequency above the edge frequency, by 5%–10%. The effect can be extended to higher edge frequencies, at least 2000 Hz, if the listener is appropriately cued. The results do not depend upon whether the coherent components are presented in phase or completely out of p...