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.

A theory for wave-power absorption by two independently oscillating bodies

Abstract: In a recent paper (Evans 1976) a theory was presented for the behaviour of an oscillating two-dimensional cylinder of any shape which was capable of absorbing energy from a given regular sinusoidal wave. In particular an expression was derived for the efficiency of power absorption of the cylinder when oscillating in a single mode in terms of properties of the solution of the so-called radiation problem in which the cylinder is forced to oscillate in the appropriate mode in the absence of the incident wave train. In the present paper this theory is extended to two independent cylinders of arbitrary shape each oscillating in a single mode and capable of absorbing energy in that mode. A general expression for the efficiency is derived which depends on properties of the solution to a new radiation problem, in which one cylinder is forced to oscillate in the presence of the other cylinder, which is held fixed in its equilibrium position. In this case, the efficiency also depends on cross-coupling coefficients related to the force on the fixed cylinder due to the motion of the oscillating cylinder. It is shown that the cylinders can be tuned to absorb all the incident wave energy at a given frequency even for symmetric cylinders, in contrast to the single symmetric cylinder, for which the maximum efficiency has been shown to be 50%. The general solution to the new radiation problem is derived in terms of the solution to the radiation problem for a single cylinder, by assuming that the cylinders are far enough apart for local wave effects to be negligible. The special case of two widely spaced rolling vertical plates is considered in detail and curves showing the variation of efficiency with wavelength are given for a variety of plate spacings and points of rotation.

Systematic error analysis of stepwise approximated AC waveforms generated by a Programmable Josephson Voltage Standard

Abstract: We have measured stepwise-approximated sine waves generated by a programmable Josephson voltage standard (PJVS) with several different output configurations. These data are analyzed to characterize the dominant error mechanisms for RMS applications, such as AC-DC difference measurements of thermal voltage converters (TVCs). We present detailed explanations of the fundamental causes and consequences of systematic errors that arise from transitions and consider the overall uncertainties for PJVS ac metrology using this synthesis method. We show that timing-related errors are sufficient to make this waveform synthesis approach impractical for RMS audio-frequency applications. The implications of providing the load current required by devices of low input impedance, such as TVCs, are also discussed.

Spatial frequency differences can determine figure-ground organization.

Abstract: In three experiments we examined the influence of spatial frequency on perceptual organization. In each experiment a pattern was tested that was ambiguous in terms of figure and ground. In each experiment, the stimuli were 20 variations of the pattern, which were generated by filling the two regions of the pattern with horizontal sine wave gratings differing in spatial frequency. Five spatial frequencies were tested: 0.5, 1, 2, 4, and 8 cycles per degree. The response measure was the percentage of response time one of the regions was seen as the figure. This region was seen as the figure a higher percentage of the time in those stimuli where it contained the relatively higher spatial frequency sine wave grating compared with those stimuli where it contained the relatively lower spatial frequency sine wave grating. Language: en

FM band multiple signal modulator

Abstract: Apparatus and a method for generating all of the assignable carrier frequencies in the FM broadcast band and for frequency modulating the generated carriers includes a generator of a train of pulses having a crystal-controlled repetition frequency and a specific pulse shape which together produce a spectrum of odd harmonics of the pulse repetition frequency whose separation in frequency is identical to that of the assignable carrier frequencies. This pulse train is then mixed with a 98.0 MHz sine wave to translate the spectrum to the FM band. Simultaneous modulation of all the carriers is achieved by frequency modulating the 98.0 MHz sine wave, whereby the same modulation is imparted simultaneously to all of the carriers.