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.

Method and apparatus for objective determination of visual contrast sensitivity functions

Abstract: A method and apparatus for objectively determining the visual contrast sensitivity function of a human subject involves subjecting the vision of the human subject to a plurality of sine wave gratings differing in spatial frequency and contrast levels. As the subject views the grating patterns on a video monitor, the brain wave activity of the subject is detected and steady state Fourier spectra of the activity are recorded. In each spectrum corresponding to a grating pattern of a particular spatial frequency, a visual evoked potential component may be distinguished from noise by adjusting the contrast level of the grating pattern. A contrast threshold used in deriving the visual contrast sensitivity function is identified for each grating pattern of a particular spatial frequency by pinpointing the contrast level at which the visual evoked potential component becomes indistinguishable from noise in the spectrum.

Scalar PWM algorithms for four-switch three-phase inverters

Abstract: Four-switch three-phase inverters (FSTPIs) have been proposed to be used in low-cost applications because of the reduced number of semiconductor devices, and space vector pulse width modulation (SVPWM) techniques have also been introduced to control FSTPIs. However, high-performance controllers are needed to implement complicated SVPWM algorithms, which limits their low-cost applications. To simplify algorithms and reduce the cost of implementation, an equivalent scalar method for SVPWM of FSTPIs is proposed. SVPWM for FSTPIs is actually a sine PWM by modulating two sine waves of 60° phase difference with a triangle wave, so such a special sine PWM can be used to control FSTPIs. The simulation and experimental results demonstrate the validity of the proposed method.

Shoaling of cnoidal waves

Abstract: An equation is derived which governs the propagation of a cnoidal wave train over a gently sloping bottom. The equation is solved numerically, the solution being tabulated in terms of fH (Eq. 47) as a function of Ei = (Etr/pg) 1/3/gT2 and hi = h/gT2. Results are compared with sinusoidal wave theory. Two numerical examples are included.

Triangle-to-sine wave conversion with MOS technology

Abstract: A description is given of MOS circuit design techniques for nonlinear analog circuits that perform a triangle-to-sine wave conversion. These techniques may also be applied to synthesizing other functions. Design techniques for compensating the conversion for variations in temperature, processing, and triangle wave amplitude are also presented. Results from simulation and monolithic circuit fabrication are reported which show that a sinusoidal approximation with a total harmonic content of 0.2% at 1 kHz is practical. The test circuit is powered from /spl plusmn/5 V supplies and displays a bandwidth of 1.1 MHz.

Ferrite losses of cores with square wave voltage and dc bias

Abstract: Ferrite material properties may vary depending on the grade and manufacturer: there are differences between batches and also the production process may change in time. On the other hand, in power applications, the usual voltage wave forms are closer to square wave than to sine wave, and moreover they contain a dc bias component that can easily more than double the ferrite losses. Therefore, in loss critical applications it is good to be able to both test and model the losses of the actual ferrite cores under the same conditions as in the actual power application. In this paper, experiments were carried out at different induction levels and dc bias currents. Losses were measured at frequencies of 20, 100, and 500 kHz on a ferrite core with Ferroxcube 3F3 material, a Mn–Zn ferrite. We observe that mainly the lower frequencies are sensitive to dc bias. A model including wide ranges in amplitude, frequency, and also dc bias is proposed. In this model, the losses are separated in three terms: a hysteresis dependent term, an additional loss term depending on dc bias, and a high frequency term.