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Alternating voltage and current
Published in Mike Tooley, Electronic Circuits, 2019
The quality of a resonant (or tuned) circuit is measured by its Q-factor. The higher the Q-factor, the sharper the response (narrower bandwidth), conversely the lower the Q-factor, the flatter the response (wider bandwidth), see Fig. 4.16. In the case of the series tuned circuit, the Q-factor will increase as the resistance, R, decreases. In the case of the parallel tuned circuit, the Q-factor will increase as the resistance, R, increases. The response of a tuned circuit can be modified by incorporating a resistance of appropriate value either to ‘dampen’ (low-Q) or ‘sharpen’ (high-Q) the response. The relationship between bandwidth and Q-factor is: Bandwidth=f2−f1=f0Q and Q=2πf0LR
Primer on Photonics
Published in Paul R. Prucnal, Bhavin J. Shastri, Malvin Carl Teich, Neuromorphic Photonics, 2017
Paul R. Prucnal, Bhavin J. Shastri, Malvin Carl Teich
The finesse is closely related to the quality (Q) factor of the cavity, which is the sharpness of a resonance relative to its center frequency. Q factor is a standard oscillator concept formally defined as the quotient of stored energy to energy lost per oscillation cycle. This is indeed a close relation to the finesse, 2π times the mean number of round trips made by light in the cavity. The quality factor of an MRR is expressed () Q=ω0FWHD=m⋅FSRFWHD=mℱ,where m is the harmonic order of the resonance of interest. m is also the number of wavelengths that fit around the ring’s circumference: () m=nLλ.
Spectrometers
Published in Daniel Malacara-Hernández, Brian J. Thompson, Fundamentals and Basic Optical Instruments, 2017
Resolution is a measure of the fineness with which the width of a spectral line can be measured. One measure of this is the full width of the measured line at half the maximum value, the FWHM. This can be given in any of the spectral variables: dλ, dσ, dk, and so on. Resolution can also be stipulated as a fraction of the wavelength: dλ/λ, dσ/σ, dk/k, and so on. This is slightly awkward in that lower values are generally better: that is, 0.01 is a higher resolution than 0.1! It is finer. Resolving power (RP) is defined as resolution that avoids this little complication. It is the reciprocal of fractional resolution: λ/dλ, σ/dσ, and so on. This is the same definition as the quality factor Q of an electrical circuit. Thus, both RP and Q are used for the resolving power of a spectrometer, and some authors use 5 and call it resolvance. The fractional resolution and resolving power are equal no matter what the spectral variable: Q=RP=σdσ=λdλ=kdk=vdv=⋅⋅⋅.
Investigation on material variants and fabrication methods for microstrip textile antennas: A review based on conventional and novel concepts of weaving, knitting and embroidery
Published in Cogent Engineering, 2022
Rameesh Lakshan Bulathsinghala
The Q factor analysis of textile-based antennas is essential since power losses of textile antennas are higher than their metallic counterparts due to the anisotropic nature of textile materials and fabrication limitations. Therefore, material variants and fabrication variants should be considered based on power losses as mentioned in Equation (1) while fabricating each component of the textile antenna. The Q factor is the ratio between electric energy stored and radiated by the conductive material, which is a measure of power loss in a microwave system. The Q-factor determines the bandwidth of the microstrip antennas. The total Q-factor (QT) is a combination of Q-factor due to lateral radiation loss (Qrlateral), Q-factor due to space wave radiation loss (Qrspace) Q-factor due to conduction loss (Qc), Q-factor due to dielectric loss (Qd) and the Q-factor due to surface wave propagation loss (Qs). The total Quality factor in terms of these Q factors is given below in Equation (1).
Displacement transmissibility based system identification for polydimethylsiloxane integrating a combination of mechanical modelling with evolutionary multi-objective optimization
Published in Engineering Optimization, 2020
Arun Kumar Sharma, Rituparna Datta, Shubham Agarwal, Bishakh Bhattacharya
Figure 13 justifies the use of multi-objective optimization for this study by comparing the Q-factor and associated error in the half-power point frequencies concerning the experimental transmissibility curve. The Q-factor is a dimensionless parameter that characterizes system behaviour around a resonant frequency relative to its centre frequency. A high Q-factor value indicates a lower rate of energy loss relative to the stored energy. In the present case, it is difficult for a single objective function to characterize system behaviour in all the controlled regions, and especially to model damping behaviour around the resonant frequency; hence the need for another objective function. Thus, to account for any un-modelled dynamics and to address the challenge of reaching closer to experimental damping, a second objective function of minimizing the peak transmissibility error bounded by the half-power point frequency error has been incorporated into the study. It can be discerned from Figures 13(b–d) that the Zener model is competent to be in the closest horizon of the experimental Q-factor and half-power frequency error, closely pursued by the Kelvin–Voigt model.
Analysis of the quality factor of micro-beam resonators based on heat conduction model with a single delay term
Published in Journal of Thermal Stresses, 2019
Harendra Kumar, Santwana Mukhopadhyay
Based on modern technology, the Micro-Electro-Mechanical Systems (MEMS) and Nano- Electro-Mechanical Systems (NEMS) are being developed due to their various applications in fields of engineering and science such as sensors, micro pumps, accelerometers, charge detectors, radio frequency (RF) filters, and so forth. One of the important application of MEMS is micromechanical resonators for their high sensitivity and fast response. For resonators, it is possible to construct and design systems with very little loss of energy dissipation during vibration. It has been observed that one of the import energy loss factors during vibration is thermoelastic damping in very small structure in size. In order to minimize energy dissipation during the vibration, we need to construct a system with high-quality factor. The quality factor is a dimensionless parameter of a micro resonator and defined as the ratio of the stored energy in the resonator and the dissipated energy by the resonator per cycle of vibration. Quality factor is also commonly termed as the Q-factor. A high value of the quality factor indicates the low rate of energy loss and therefore in such case, oscillations will gradually reduce. This implies that oscillations will ring or vibrate for a long time.