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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: In this paper, the authors investigated the power absorbed by the electrons Pe as a function of θ and time experimentally, by a particle in cell simulation, and an analytical model.
Abstract: The symmetry of capacitive radio frequency discharges can be controlled via the electrical asymmetry effect by driving one electrode with a fundamental frequency and its second harmonic. In such electrically asymmetric discharges, the mean ion energies at both electrodes are controlled separately from the ion flux by tuning the phase angle θ between the harmonics at fixed voltage amplitudes. Here, the question why the ion flux is nearly independent of θ is answered by investigating the power absorbed by the electrons Pe as a function of θ and time experimentally, by a particle in cell simulation, and an analytical model. The dynamics of Pe is understood by the model and is found to be strongly affected by the choice of θ. However, on time average, Pe is nearly constant, independently of θ. Thus, the ion flux remains approximately constant. In addition, it is shown that the absolute value of the individual voltages across the powered and grounded electrode sheath vary linearly with the dc self-bias. Howeve...

47 citations

Journal ArticleDOI
TL;DR: In this paper, a combined resonant-repetitive (RR) control structure for a three-phase four-leg dc/ac converter power supply is proposed, which is composed by a resonant controller tuned at the system fundamental frequency working in conjunction with a plug-in-type repetitive controller.
Abstract: This paper investigates a combined resonant–repetitive (RR) control structure for a three-phase four-leg dc/ac converter power supply. The RR control configuration is composed by a resonant controller tuned at the system fundamental frequency working in conjunction with a plug-in-type repetitive controller. The resonant part of the control scheme is used to assure prompt tracking of the inverter output voltage and to achieve as fast as possible system response to load variations; to this purpose, it is tuned at the fundamental frequency. At the same time, the resonant controller is able to stabilize the system without the necessity of any further additional controller; the repetitive part of the scheme is implemented for the fine regulation at the system harmonic frequencies. The proposed control configuration is used to regulate the power supply output voltage, providing very good tracking of the output voltage reference even in the presence of a nonlinear load. Experimental validation from a 40-kVA converter prototype is presented to validate the operation of the proposed converter and control.

47 citations

Journal ArticleDOI
TL;DR: In this paper, the application of compact non-uniform transmission line transformers (NTLTs) in suppressing and controlling the odd harmonics of the fundamental frequency is presented.
Abstract: In this paper, the application of compact non-uniform transmission line transformers (NTLTs) in suppressing and controlling the odd harmonics of the fundamental frequency is presented. A design example showing the complete suppression of the odd harmonics of the fundamental frequency is given. In addition, several compact NTLTs are designed showing the possibility of controlling the existence of a fundamental frequency's odd harmonics. Moreover, multi-band operation using NTLTs is investigated. Speciflcally, a design example of a miniaturized triple-frequency NTLT is introduced. Based on these compact NTLTs, a 3-way triple-frequency modifled Bagley power divider (BPD) with a size reduction of 50%, and a 5-way modifled BPD with harmonics suppression and size reduction of 34%, are designed. For veriflcation purposes, both dividers are simulated using the two full-wave simulators IE3D and HFSS. Moreover, the modifled 5-way BPD with harmonics suppression is fabricated and measured. Both the simulation and measurement results validate the design approach.

47 citations

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate experimentally, theoretically, and numerically for the first time, a wide-range tunability of an in-plane clamped-clamped microbeam, bridge, and resonator actuated electrothermally and electrostatically.
Abstract: This paper demonstrates experimentally, theoretically, and numerically for the first time, a wide-range tunability of an in-plane clamped–clamped microbeam, bridge, and resonator actuated electrothermally and electrostatically. Using both actuation methods, we demonstrate that a single resonator can be operated at a wide range of frequencies. The microbeam is actuated electrothermally by passing a dc current through it, and electrostatically by applying a dc polarization voltage between the microbeam and the stationary electrode. We show that when increasing the electrothermal voltage, the compressive stress inside the microbeam increases, which leads eventually to its buckling. Before buckling, the fundamental frequency decreases until it drops to very low values, almost to zero. After buckling, the fundamental frequency increases, which is shown to be as high as twice the original resonance frequency. Adding a dc bias changes the qualitative nature of the tunability both before and after buckling, which adds another independent way of tuning. This reduces the dip before buckling, and can eliminate it if desired, and further increases the fundamental frequency after buckling. Analytical results based on the Galerkin discretization of the Euler Bernoulli beam theory are generated and compared with the experimental data and simulation results of a multi-physics finite-element model. A good agreement is found among all the results. [2015-0341]

47 citations

Journal ArticleDOI
TL;DR: A contact (accelerometer) microphone placed on the neck below the cricoid cartilage and an electroglottograph for measurement of fundamental frequency in connected speech are compared.
Abstract: Signals from a throat contact microphone or an electroglottograph often are more suited for fundamental frequency measurements with simple analog circuits than the radiated speech signal. This report compares a contact (accelerometer) microphone placed on the neck below the cricoid cartilage and an electroglottograph for measurement of fundamental frequency in connected speech. The advantages and drawbacks of the two methods are discussed.

46 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202344
2022101
2021236
2020335
2019421
2018375