Topic
Fundamental frequency
About: Fundamental frequency is a research topic. Over the lifetime, 8941 publications have been published within this topic receiving 131583 citations.
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TL;DR: Effects of thermal stresses on stability and frequency response of a fully clamped circular microplate, which acts as the diaphragm of a capacitive MEMS microphone, and effects of the electrostatic force and the temperature variation on the frequency response are investigated.
40 citations
TL;DR: In this article, the fundamental frequency of in-plane, inextensional vibration of ring-like structures is determined and compared with the value predicted by the optimized Rayleigh-Ritz method.
40 citations
TL;DR: The pitch matching experiment described at the previous meeting was extended to filtered stimuli as discussed by the authors, where listeners adjusted the frequency of an unfiltered periodic pulse-train to match the pitch of a train which was high-pass filtered to remove the fundamental component.
Abstract: The pitch‐matching experiment described at the previous meeting was extended to filtered stimuli. Listeners adjusted the frequency of an unfiltered periodic pulse‐train to match the pitch of a train which was high‐pass filtered to remove the fundamental component. The stimuli were three combinations of plus and minus pulses per fundamental period: (a) +; (b) +, −; (c) +, +, −, −. The interpulse interval was an integral divisor of the fundamental period. Before being filtered, the pulses were rectangular, equal in amplitude, and 0.1 msec in duration. Listening was done in quiet at a sensation level of approximately 45 db with earphones connected binaurally in phase. The results indicate that for fundamental frequencies less than about 50 cps the pitch ascribed to the filtered stimuli is equal the number of pulses per second, regardless of pulse polarity. For fundamental frequencies greater than about 500 cps, the pitch ascribed equals, or approaches, the frequency of the lowest component passing the high‐pass filter. Matches in the range 50 to 500 cps tend to equate the fundamental frequencies of the filtered and unfiltered stimuli. Toward explication, the amplitude and phase spectra of the stimuli are considered, and an electrical analog of the basilar membrane is used in an effort to relate the subjective results to patterns of membrane displacement.
40 citations
TL;DR: In this article, the Lomb-Scargle periodogram, the Weighted Wavelet Z-transform and the improved Phase Dispersion Minimization were used to search for candidate periodicities in the radio light curves of a typical blazar 1156+295 at 14.5, 8.0 and 4.8 GHz.
Abstract: (Quasi)-periodic oscillations of the radio luminosity of a typical blazar 1156+295 were analysed to investigate the dynamic processes associated with the central engine of the active galactic nucleus. Three numerical techniques, the Lomb-Scargle periodogram, the Weighted Wavelet Z-transform and the improved Phase Dispersion Minimization, were used to search for candidate periodicities in the radio light curves of 1156+295 at 14.5, 8.0 and 4.8 GHz. The results of these methods are consistent with the detection of four periodic components with characteristic periods of similar to 1.7 (P-4), similar to 2.4 (P-3), similar to 3.4 (P-2) and similar to 7.5 yr (P-1), which suggest a harmonic relationship in frequency of 4: 3: 2: 1 with f(1) as the fundamental frequency. Except for the fact that P-1 persistently shows in the whole time span, the three others appear intermittent and are only prominent during certain time ranges. The second harmonic mode (P-2) is most powerful at all three observing frequency bands. The multiplicity and harmonic relation of the periodicities in 1156+295 reconfirms that global p-mode oscillations of the accretion disc are coupled to the jet. The oscillation of the disc is likely driven by Kelvin-Helmholtz instabilities in the inner edge of the accretion disc.
40 citations
TL;DR: In this article, the performance of a technique for the estimation of single-phase grid voltage fundamental frequency under distorted grid conditions is reported, which combines a Teager energy operator with a frequency adaptive bandpass filter (BPF).
Abstract: This paper reports the performance of a technique for the estimation of single-phase grid voltage fundamental frequency under distorted grid conditions. The technique combines a Teager energy operator (TEO) with a frequency adaptive bandpass filter (BPF). The TEO is based on three consecutive samples and is used to estimate the fundamental frequency. The BPF relies on a recursive discrete Fourier transform (RDFT) and an inverse RDFT, and is used to extract the normalized amplitude of the grid voltage fundamental component. The technique is computationally efficient and can also reject the negative effects caused by dc offset and harmonics. It requires less computational effort, can provide faster estimation, and is also less affected by harmonics as compared with a technique relying on the RDFT-based decomposition of the single-phase system into orthogonal components. The performance of the technique is verified using both simulation and experimental results.
40 citations