Topic
Fundamental frequency
About: Fundamental frequency is a research topic. Over the lifetime, 8941 publications have been published within this topic receiving 131583 citations.
Papers published on a yearly basis
Papers
More filters
Patent•
26 Oct 1994TL;DR: A lamp driving circuit with a series inductor and a capacitor (L-C) was considered in this paper, in which the lamp load was connected in parallel with the capacitor, and the resonant frequency of the series connected L-C circuit is at least √5 times greater than the fundamental frequency but not equal to the higher odd harmonic frequencies, preferably less than the third harmonic of the driving signal.
Abstract: A lamp driving circuit having a series inductor and capacitor (L-C) in which the lamp load is connected in parallel with the capacitor. During pre-ignition of the lamp load, the driving signal supplied by a half-bridge oscillator includes a fundamental frequency and higher odd harmonics including a third harmonic of the fundamental frequency. The resonant frequency of the series connected L-C circuit is at least √5 times greater than the fundamental frequency but not equal to the higher odd harmonic frequencies, preferably less than the third harmonic of the driving signal.
33 citations
TL;DR: In this paper, the problem of determining the optimal dimensions of the undercut so that the frequencies of modes 2 and 3 of transverse motion are harmonically related with that of the fundamental (mode 1) was addressed.
Abstract: Beams used in certain percussion instruments with definite pitch such as marimba, xylophone, and vibraphone are undercut in order to bring the frequencies of the first few overtones into a harmonic relationship with the fundamental frequency. This paper addresses the problem of determining the optimal dimensions of the undercut so that the frequencies of modes 2 and 3 of transverse motion are harmonically related with that of the fundamental (mode 1). The undercut is assumed to have a parabolic shape described by two variable parameters related to its depth and width. The rest of the beam on each side of the undercut is assumed to be uniform. Seven pairs of optimal undercut parameters are found that bring the frequencies of the first three transverse modes into the harmonic (integer) ratios 1:3:6, 1:4:8–9, and 1:5:10–13. Calculations performed with and without taking into account the effects of rotary inertia and shear stress are compared against measurements taken from a set of experimental beams. The comparison shows that including the effects of rotary inertia and shear stress results in a better prediction of the optimal parameters of the undercut.
33 citations
TL;DR: In this article, the displacement amplitude is expressed in terms of a double Fourier series which satisfies identically the boundary conditions and constitutes the exact solution in the case of a solid rectangular plate of uniform thickness.
33 citations
TL;DR: In this article, it was demonstrated that the temporal processing mechanisms in the auditory brainstem are essential for important aspects of musical perception, like the perception of pitch, and that the signal envelope periodicity corresponds to the fundamental frequency of signals and reflects periodic vibrations of sound sources.
Abstract: In order to understand our ability to perceive music, we have to understand how our auditory neurons process acoustic signals It is demonstrated here that temporal processing mechanisms in the auditory brainstem are essential for important aspects of musical perception, like the perception of pitch Neurophysiological experiments revealed that the temporal feature important for pitch is the periodicity of signal envelopes The corresponding evidence from neurophysiological, anatomical, and psychophysical experiments will be summarized The envelope periodicity corresponds to the fundamental frequency of signals and reflects periodic vibrations of sound sources As a consequence of the cochlear analysis, periodicity is represented not only in the firing patterns of auditory nerve fibers which code the fundamental frequency, but also in those which are involved in the spectral coding of overtones In the brainstem intrinsic neuronal oscillations, temporal integration, and coincidence detection con
33 citations
TL;DR: In this paper, a new pulse amplitude width modulation (PAWM) procedure was proposed for cascaded H-bridge multilevel inverters fed by dc voltage sources with unequal amplitudes.
Abstract: This paper proposes a new pulse amplitude width modulation (PAWM) procedure for cascaded H-bridge multilevel inverters fed by dc voltage sources with unequal amplitudes. With proposed procedure, the generated output voltage is obtained modulating a sinusoidal reference signal at the desired fundamental frequency with equally spaced switching angles. It has been analytically demonstrated that, under these assumptions, all harmonics except those of order $n=2kl\pm 1$ , $k=1,2,\ldots$ are deleted from the output voltage waveform. After a detailed description of the method and a comparative analysis with others existing in the literature, its harmonics elimination capability has been experimentally verified with 5-, 7-, 9-, and 11-level cascaded H-bridge inverters, moreover, it has been mathematically demonstrated that it reduces total harmonic distortion below 5% with a 17-level inverter and it is capable of eliminating the first 49 harmonics considered by standards with a 27-level inverter.
33 citations