Measured Quality Factor Research Articles

Probing the acoustic losses of graphene with a low-loss quartz bulk-acoustic-wave resonator at cryogenic temperatures

We observe mechanical effects of an exfoliated graphene monolayer deposited on a quartz crystal substrate designed to operate as an extremely low-loss bulk-acoustic-wave cavity at liquid-helium temperature. This is achieved by sensing overtones of the three thickness eigen-modes of the so-called SC-cut, since all three modes, two shear mode and one extensional mode, can be electrically probed with such a crystal cut. From quality-factor measurements, the mechanical losses of the adhesive graphene monolayer are assessed to be about 8×10−4 at 4 K in the best case. They are therefore significantly greater than those already reported for suspended membranes but also for adherent layers on SiO2/Si substrates operating in torsional modes. In fact, results reveal that surface scattering occurs due to a roughness degradation of a factor 7. In addition, the mechanical losses presented here are also placed in the context of a device submitted to thermomechanical stresses, but which are not the only ones existing. Some of them could be intrinsic ones related to the deposition process of the graphene layer. Based on a force-frequency theory applied to the three thickness modes which react differently to stresses, it is demonstrated that this stress effect actually entangled with that of mass loading reconciles the experimental results.

Dual-band bound states in the continuum based on hybridization of surface lattice resonances

Abstract We propose and experimentally demonstrate a novel strategy to achieve dual-band symmetry-protected bound states in the continuum (BICs) in silicon metasurfaces. This strategy is based on the hybridization of Mie surface lattice resonances (SLRs) in periodic silicon bipartite nanodisk arrays, of which the central nanodisk displaced from the center of the unit cell. We show that dual-band electric quadrupole and magnetic dipole BICs can be supported in such a system, and transfer to quasi-BICs with ultrahigh measured quality factors up to 1240 at the Γ point. Taking advantage of the SLR characteristics, we show that the spectral separation and the quality factors of these two quasi-BICs can be conveniently tuned by varying the nanodisk diameter or the lattice period. Making use of these dual-band quasi-BICs, we numerically obtain bulk sensitivities above 480 nm/RIU and high figures of merit up to 1200. We also show that when the central nanodisk is not displaced but has different diameter, the silicon bipartite nanodisk array supports an electric dipole BIC that was referred to as subradiant SLR in the literature. Our work provides a new approach for realizing and tuning dual-band BICs, and the obtained ultrahigh-Q quasi-BICs can find potential applications in nonlinear optics, multimodal lasing, and optical sensing.

FPGA‐based control strategy of five‐phase induction motor drives

Here, a novel control technique for Five-Phase Induction Motor (FPIM) drives using a field-programmable gate array (FPGA) controller is proposed. Open-loop control is analysed in terms of the performance and measurement of various power quality factors, such as voltage harmonics, current harmonics, total harmonic distortion, crest factor, unbalanced, short and long-term flickering, K-factor, real power, reactive power, apparent power, and power factor. This study experimentally demonstrated a closed-loop system with both PID and DTC controls for the FPIM. Diminished torque pulsation is obtained by efficiently utilizing the voltage vectors from the total states of 25 = 32. A novel EG voltage vector sequence was proposed for DTC techniques and compared with small, medium, and large voltage vector sequences. Proposed innovative control programming techniques in spartan-6 XC6SLX25 series FPGA for switching the five-phase two-level inverter to reduce the total harmonics distortion by less than 2%.

On Silicon-Integrated Micro-Transformers and Their Applications in Quasi-Resonant Flyback Converters

This article has shown the design and characterization of silicon-integrated thin-film micro-transformers and their application in a quasi-resonant flyback converter. Two micro-transformers with different turn ratios of 4:4 and 3:3 were designed. The micro-transformers in this study have elongated spiral shape windings sandwiched between two layers of the thin-film magnetic core, and this structure can leverage the anisotropic core property. The micro-transformers were built on a silicon substrate using micro-electro-mechanical systems (MEMSs) fabrication process to ensure a high integration level and high power density. The inductance of 4:4 and 3:3 micro-transformers are 57.3 and 31.5 nH, respectively, their coupling coefficients are 90.5% and 82.7% at 30–40 MHz, and the measured quality factors are 7.82 at 21 MHz and 8.94 at 35 MHz, respectively. A resonant flyback converter topology deploying with a high electron mobility transistor [Gallium nitride (GaN)] was used to evaluate the electrical performance of two micro-transformers. Two resonant flyback converters operating at zero voltage switching (ZVS) reached the maximum conversion efficiency of 46.4% (3:3) and 45.7% (4:4), respectively, with 3.3 V input. The 3:3 micro-transformer developed in this work achieved the highest power density of 128 mW/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with a similar efficiency compared to other cored micro-transformers. The loss analysis of the flyback conversion circuit shows that the main losses in the circuit are the copper winding loss of the micro-transformer and the eddy current loss of the magnetic core. The conversion efficiency of the circuit will be improved by applying thicker copper and core lamination in the future.

High Efficiency Wireless Power Transmission System That Uses HTS Transmitting and Copper Receiving Coils With a Large Difference in Quality Factor

We developed an efficient wireless power transmission (WPT) system using a high-temperature superconductor (HTS) spiral coil with a high quality factor as the transmitting coil and a copper coil as the receiving coil. The HTS spiral coil was fabricated using double-sided HTS wire which we developed previously. The double-sided HTS wire consists of two conventional HTS coated conductor wires. The measured quality factor of the HTS spiral coil containing modified coil support was about 14 times higher than that of the copper coil. We designed the WPT system using the filter design theory. We measured the design parameters for a coupling coefficient and an external quality factor. We measured the power transmission efficiency (PTE) of the WPT in the facing direction, position misalignment, and angular misalignment. The PTE of the WPT system with the high quality factor HTS spiral coil showed significant improvements in all measurements compared to the system with copper coils.

Thermal resonance model for micro-oscillators in the vicinity of a geometric boundary

This study explores the damping behavior of micro-oscillators within the transitional flow regime between molecular flow and viscous flow, including the presence of a neighboring geometric boundary. The damping is described by a model based on standing thermal waves (STW), which form a thermal resonance depending on the pressure and on the gap width to the boundary. This concept was first introduced in a previous paper for a nitrogen atmosphere and is now examined for seven further gases (He, Ne, Ar, Kr, CO2, N2O, SF6). The distance between the micro-oscillator and the confining geometry, given by an Al plate, is in the range of 150 µm to 3500 µm. Fitting the thermal wave model to the experimental data shows very good agreement and explains the convex region for the measured quality factor Q in the transition from the molecular to the viscous flow regime. The evaluation of the thermal resonance model shows a strong correlation between the ambient pressure at which thermal resonance occurs and the thermal properties of the gas (i.e. thermal diffusivity a and adiabatic index κ) including the gap width h which is in agreement with the proposed theory. This opens up the possibility of using micro-oscillators to measure the thermal properties of gases in a very precise way, comparable to the thermal wave resonator cavity principle, but with a much simpler and smaller setup.

Q-factor estimation from surface seismic data in the time-frequency domain: A comparative analysis

The quality factor Q is generally used to describe seismic attenuation that leads to amplitude decay (AD) and wavelet distortion. Time-frequency transforms are commonly used to measure quality factor Q on surface seismic data. These methods capture frequency changes over time using a fixed or variable sliding time window. Other adaptive transforms also can provide time localization, and they often are superior for Q estimation. In this study, we compare three time-frequency transforms and indicate how the choice of a fixed- or variable-time window or an adaptive transform affects the accuracy and robustness of Q-factor estimation. We use the short-time Fourier and continuous wavelet transforms as fixed- and variable-window transforms, respectively. The synchrosqueezed wavelet transform is used as an adaptive transform. We compare four Q-factor estimation methods in the time-frequency domain, such as the AD, spectral ratio, centroid frequency shift, and compound time-frequency variable methods. Furthermore, we study some of the difficulties associated with these estimation methods, such as quantitative attenuation sensitivity, noise robustness, regression bandwidth influence, and key parameter selection for each time-frequency transform. Real data examples are used to investigate the robustness of Q-factor estimation with different methods using different time-frequency transforms and the statistics of how well the attenuation measurements match the expected seismic attenuation behavior. Furthermore, in these real data examples, we are able to use the Q estimates to compensate for attenuation through inverse Q filtering.

Self-assembled silicon membrane resonator for high vacuum pressure sensing

In this paper, a mechanical vacuum gauge based on a circular membrane resonator is proposed and its high responsivity is verified in high vacuum down to a pressure of ∼6 × 10−7 mbar. A silicon-on-nothing (SON) resonator with a self-sealed cavity having a diameter of 150μm and a thickness of 1.55μm is fabricated through a high vacuum annealing process. After the fabricated membrane resonator is placed inside a custom vacuum chamber, its resonant characteristics are measured with a frequency sweep, and the vibration amplitudes are measured by resonance feedback using a laser and photodiodes at various vacuum pressures. Using quality factor (Q factor) measurement, the SON resonator shows a high responsivity (ΔQ/ΔP) of up to ∼3.7 × 108 mbar−1 in the high vacuum range. Both quality factor and amplitude are found to be effective vacuum indicators, and amplitude measurement is specifically useful for real-time vacuum monitoring.

Effects of Remote Boundary Conditions on Clamping Loss in Micromechanical Resonators

Clamping loss in micromechanical resonators can strongly depend on the boundary conditions far away from the actual vibrating structure because the acoustic wavelength greatly exceeds the device dimensions. We demonstrate a scheme for post-fabrication tuning of the clamping loss in flexural-mode and bulk-mode resonators by modifying the boundary conditions of the chip with the frame. The measured quality factor increases by more than an order-of-magnitude for the microcantilevers and more than a factor of three for the bulk-mode resonators when frame contact is minimized via suspension of the chip by wirebonds. We propose a two-degree-of-freedom fluctuation-dissipation model to describe the thermomechanical noise and forced response in the presence of this tunable anchor damping. By studying the thermomechanical displacement spectrum with tunable clamping loss, we show that variable clamping loss tunes the mechanical quality factor, modifying both the resonator transfer function and thermomechanical noise force. We delineate the dependence of the tunable clamping loss mechanism on microcantilever beam length and ambient temperature from 300 K down to 40 K, and observe potential temperature dependence to clamping loss with reducing temperature. [2021-0141]

A Sensor for Characterisation of Liquid Materials with High Permittivity and High Dielectric Loss.

This paper reports on a sensor based on multi-element complementary split-ring resonator for the measurement of liquid materials. The resonator consists of three split rings for improved measurement sensitivity. A hole is fabricated at the centre of the rings to accommodate a hollow glass tube, through which the liquid sample can be injected. Electromagnetic simulations demonstrate that both the resonant frequency and quality factor of the sensor vary considerably with the dielectric constant and loss tangent of the liquid sample. The volume ratio between the liquid sample and glass tube is 0.36, yielding great sensitivity in the measured results for high loss liquids. Compared to the design based on rectangular split rings, the proposed ring structure offers 37% larger frequency shifts and 9.1% greater resonant dips. The relationship between dielectric constant, loss tangent, measured quality factor and resonant frequency is derived. Experimental verification is conducted using ethanol solution with different concentrations. The measurement accuracy is calculated to be within 2.8%, and this validates the proposed approach.

An indoor environmental quality distribution map based on spatial interpolation methods

Extensive and precise measurements of indoor environment quality (IEQ) factors are needed to manage the IEQ of large spaces such as multi-use facilities. In particular, it is significantly important to estimate the IEQ of a point where sensor installation is difficult. This study aimed to develop a spatial IEQ distribution map for multi-use facilities based on spatial interpolation methods. A total of 18 monitoring sensors were installed in the library's reading room, among which 14 were collection sensors used for the IEQ distribution map development. The remaining four sensors were verification sensors used to assess the measured and predicted values' accuracy. The optimal spatial interpolation method with a high degree of accuracy for each IEQ factor was derived, and the versatility of the IEQ distribution map was verified through accuracy assessments for four scenarios. The optimal number and layout of collection sensors required to develop the IEQ distribution map were also determined for each IEQ factor. It is expected that the IEQ distribution map derived from this study will allow users to quickly and easily understand the IEQ condition inside the library's reading room and enable administrators to diagnose the spatial-temporal environmental data of the library reading room using a small number of monitoring sensors.

High-Performance Multi-MHz Capacitive Wireless Power Transfer System for EV Charging Utilizing Interleaved-Foil Coupled Inductors

This article introduces a kilowatt-scale large air-gap capacitive wireless power transfer (WPT) system for electric vehicle (EV) charging that achieves high-power transfer density and high efficiency. High-power transfer density is achieved by operating at a multi-MHz frequency (13.56 MHz), and by utilizing innovatively designed matching networks that enable effective power transfer by providing gain and reactive compensation while absorbing the parasitics present in the EV charging environment. High efficiency is achieved through the use of new interleaved-foil air-core coupled inductors in the matching networks. Interleaved-foil inductors provide a better tradeoff between quality factor, size, and self-resonant frequency compared to conventional solenoidal inductors, making them suitable for compactly and efficiently processing kilowatt-scale power at multi-MHz frequencies. Two variants of the interleaved-foil concept are presented: a semi-toroidal interleaved foil (STIF) inductor and a toroidal interleaved-foil (TIF) inductor. The superior performance of interleaved-foil inductors is demonstrated using analytical formulations, which are validated through finite-element analysis and measurements. Compared to the highest-quality-factor solenoidal inductor, the STIF inductor is shown to achieve 32% smaller box volume while having only 3% lower measured quality factor, while the TIF inductor is shown to achieve an even better tradeoff with 27% smaller box volume and 30% higher measured quality factor. A 13.56-MHz, 12-cm air-gap prototype capacitive WPT system utilizing TIF inductors with a quality factor of 2055 in its matching networks is designed, built, and tested. This system achieves record-breaking performance for a capacitive EV charging system, with an efficiency of 94.7% while transferring 3.75 kW using 22-cm-diameter coupling plates, corresponding to a power transfer density of 49.4 kW/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . This TIF-inductor-based prototype is also shown to outperform a second high-performance prototype utilizing STIF inductors.

Ultrahigh-Quality Infrared Polaritonic Resonators Based on Bottom-Up-Synthesized van der Waals Nanoribbons.

van der Waals nanomaterials supporting phonon polariton quasiparticles possess extraordinary light confinement capabilities, making them ideal systems for molecular sensing, thermal emission, and subwavelength imaging applications, but they require defect-free crystallinity and nanostructured form factors to fully showcase these capabilities. We introduce bottom-up-synthesized α-MoO3 structures as nanoscale phonon polaritonic systems that feature tailorable morphologies and crystal qualities consistent with bulk single crystals. α-MoO3 nanoribbons serve as low-loss hyperbolic Fabry-Pérot nanoresonators, and we experimentally map hyperbolic resonances over four Reststrahlen bands spanning the far- and mid-infrared spectral range, including resonance modes beyond the 10th order. The measured quality factors are the highest from phonon polaritonic van der Waals structures to date. We anticipate that bottom-up-synthesized polaritonic van der Waals nanostructures will serve as an enabling high-performance and low-loss platform for infrared optical and optoelectronic applications.

A Fast Tracking and Wide Swing CMOS Peak Detector for On-Chip Q-Factor Measurement

In this paper, a CMOS peak detector is proposed in order to satisfy the requirement of an on-chip time-domain quality factor (Q-factor) measurement. Unlike a conventional peak detector in which an Operational Trans-conductance Amplifier (OTA) is used as the core circuit, a high-speed comparator is deployed as the core circuit within the proposed peak detector. As a result, the proposed peak detector can offer a fast peak tracking with a high dynamic range and over a large voltage swing while still covering a wide frequency span with an excellent linearity and accuracy, which are key features required by on-chip Q-factor measurement. The proposed circuit was implemented in a CMOS 0.35&#x03BC;m technology under 5V. The experimental results have shown an output swing almost 4Vpp for an input signal amplitude ranging from 0.02V to 1.9V with a maximum signal dynamic ratio of 50 (Vmax/Vmin), an excellent linearity with a relative error &#x003C;0.2%, a peak tracking accuracy less than 0.7% for 1MHz and a fast peak tracking with only one period delay in the worst case. The experimental results show that the operating frequency spans from 100 kHz to 5MHz and power consumption is around 9mW within this frequency range.

Study of phase and amplitude-phase methods for measuring a reactive element quality factor

The paper considers improving accuracy of measured parameters and quality factors of reactive components. To increase the accuracy of measurement, circuit diagrams of new measuring transducers for measuring the quality factor of reactive elements for operation in a wide range of frequencies are developed. These measuring transducers provide reducing the standard uncertainty of the quality factor measurement for reactive elements with a slight complication of the measuring instrument. A phase and amplitude-phase methods of measuring the quality factor of reactive elements are considered, which provide the measurement standard uncertainty reduction. These methods have a relatively high measurement accuracy and are easy to implement on the microprocessor-based technology. Quality factors of inductive and capacitive elements are shown to be determined by measuring the phase shift angle between two output voltages of the measuring transducer. A prototype of the measuring transducer was installed to verify experimentally obtained theoretical results. Studies were performed for three inductors of different types and for low-power high-frequency capacitors. Theoretical and experimental dependences were investigated and compared.

Measuring quality factors of the radio-frequency system components using equivalent circuits

Measuring quality factors of the radio-frequency system components using equivalent circuits

Pressure-based defect mode tunability in a one-dimensional photonic crystal composed of SiO2 and Si

This work assesses the dependence of the refractive index of a one-dimensional photonic crystal composed of SiO2 and Si on its applied pressure. Therefore, the Transfer Matrix Method is used to calculate its transmittance spectrum. After breaking the structure periodicity, we found the photonic band gaps of a defect mode, which may be tuned by increasing the external pressure applied. In addition, we reported that when increasing pressure, and depending on the layer arrangement within the crystal, we can maximize the energy stored by the defect mode through quality factor measurements.

Rf measurements and tuning of the 1-m-long 750 MHz radio-frequency quadrupole for artwork analysis

The 750 MHz PIXE-RFQ (radio-frequency quadrupole), developed and built at CERN, provides 2 MeV protons over a length of one meter for proton-induced X-ray emission analysis (PIXE) of cultural heritage artwork. In this paper, we report low-power rf measurements and tuning of the PIXE-RFQ, which have been completed mid-2020. Using a novel algorithm based on direct measurements of the response matrix, field and frequency could be tuned at the same time in only two steps to satisfying accuracy. Additionally, we report measurements of single modules, quality factors, and coupling strength. In all cases, very good agreement between rf measurement and design values was observed.

Coupling of a single tin-vacancy center to a photonic crystal cavity in diamond

We demonstrate optical coupling between a single tin-vacancy (SnV) center in diamond and a free-standing photonic crystal nanobeam cavity. The cavities are fabricated using quasi-isotropic etching and feature experimentally measured quality factors as high as ∼11 000. We investigate the dependence of a single SnV center's emission by controlling the cavity wavelength using a laser-induced gas desorption technique. Under resonance conditions, we observe an intensity enhancement of the SnV emission by a factor of 12 and a 16-fold reduction of the SnV lifetime. Based on the large enhancement of the SnV emission rate inside the cavity, we estimate the Purcell factor for the SnV zero-phonon line to be 37 and the coupling efficiency of the SnV center to the cavity, the β factor, to be 95%. Our work paves the way for the realization of quantum photonic devices and systems based on efficient photonic interfaces using the SnV color center in diamond.

A Proposal Video Encryption Using Light Stream Algorithm

Video encrypting is one technique to protect digital videos, it used to avoid unwanted interference and viewing of the transmitted videos. In this paper, a new selective video cryptography algorithm is suggested using light stream algorithm. As it known video size is large in size and it consume time in the encryption process, ChaCha a light encryption algorithm has been used to reduce the encryption time, encryption is done by Xoring frames of video with the key generated from ChaCha algorithm, it produced an acceptable results from robustness point view, but still encryption process consumed time, thus to speed up this process, feature detection operator (FAST) is used to encrypt key points result from FAST operator, in addition key points from this is increased to optimized between speed and robustness of proposed algorithm. In evaluation process, some of measuring quality factors MSE, PSNR, Correlation, NPCR, UACI and entropy are specified for evaluating and comparing between two suggested encryption algorithms which gave good result in encryption process (ChaCha and ChaCha with FAST Enhancement). Experimental results have discovered that the current projected has less encrypting time and better encrypting influence.