Improved Quality Factor Research Articles

Analysis of Multi-Stacked Dielectric Resonator Antenna with Its Equivalent R-L-C Circuit Modeling for Wireless Communication Systems

The dielectric resonator antenna (DRA) can be modeled as a series and parallel combination of electrical networks consisting of a resistor (R), inductor (L), and capacitor (C) to address peculiar challenges in antennas suitable for application in emerging wireless communication systems for higher frequency range. In this paper, a multi-stacked DRA has been proposed. The performance and characteristic features of the DRA have been analyzed by deriving the mathematical formulations for dynamic impedance, input impedance, admittance, bandwidth, and quality factor for fundamental and high-order resonant modes. Specifically, the performance of the projected multi-stacked DRA was analyzed in MATLAB and a high-frequency structure simulator (HFSS). Generally, results indicate that variation in the permittivity of substrates, such as high and low, can potentially increase and decrease the quality factor, respectively. In particular, the impedance, radiation fields and power flow have been demonstrated using the proposed multi-stacked electrical network of R, L, and C components coupled with a suitable transformer. Overall, the proposed multi-stacked DRA network shows an improved quality factor and selectivity, and bandwidth is reduced reasonably. The multi-stacked DRA network would find useful applications in radio frequency wireless communication systems. Additionally, for enhancing the impedance, BW of DRA a multi-stacked DRA is proposed by the use of ground-plane techniques with slots, dual-segment, and stacked DRA. The performance of multi-stacked DRA is improved by a factor of 10% as compared to existing models in terms of better flexibility, moderate gain, compact size, bandwidth, quality factor, resonant frequency, frequency impedance at the resonance frequency, and the radiation pattern with Terahertz frequency range.

Surface Passivation of Niobium Superconducting Quantum Circuits Using Self-Assembled Monolayers

Superconducting coplanar waveguide (CPW) microwave resonators in quantum circuits are the best components for reading and changing the state of artificial atoms because of their excellent coupling to quantum systems. This coupling forms the basis of the developing circuit quantum electrodynamic architecture. In quantum processors, oscillators are used to store and transmit quantum information using microwave-frequency wave packets. However, the presence of amorphous thin-film defects is deleterious and can result in an irrevocable loss of coherent information with uncontrolled degrees of freedom. Although there has been extensive research into techniques to reduce the coherent loss of such devices, the precise structure of amorphous dielectric layers on surfaces and interfaces and their associated loss mechanism are being actively studied. In particular, planar superconducting resonators are very sensitive to defects on their surfaces, such as two-level systems in oxidized metals and nonequilibrium quasiparticles, making these devices suitable probes for the different loss mechanisms. In this work, we present the design, fabrication, and characterization of Nb CPW resonators with different surface treatments with self-assembled monolayers (SAMs), which mitigate the growth of oxides in superconducting circuits. We demonstrate SAM-passivated resonators having internal quality factors of greater than 106 at a single-photon excitation power (measured at 100 mK), which were probed using scanning electron microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy to demonstrate the efficiency of our surface treatment. Finally, we compared the improvements in the experimental quality factors to those obtained by numerical simulation.

Ultra-wide band and improved quality factor SH-type SAW devices by employing Mn-doped Pb(In1/2Nb1/2)O3– Pb(Mg1/3Nb2/3)O3–PbTiO3 thin film/diamond layered structure

This paper presents a piezoelectric layered structure composed of Mn-doped PIN-PMN-PT thin film combined with diamond for high electromechanical coupling factor (K2) and improved quality factor (Q) SAW devices. Comprehensive theoretical analysis of SAW resonator on the proposed structure is performed to calculate its SAW characteristics including K2, V (phase velocity) and Q. The influence of the Euler angle, Mn-doped PIN-PMN-PT layer's thickness and the electrode's thickness as well as electrode's materials on the SAW properties are investigated. It is shown that the maximum electromechanical coupling factor of the proposed structure has been theoretically shown up to be 79.5 % for the main mode called shear-horizontal (SH)-type SAW. The FOM(K2·Q) is enhanced to 868.5, which is more than two times larger than that of the previously reported work using pure PIN-PMN-PT. Such enhancement of FOM makes such structure has great potential application in ultra-wide band and high Q SAW filters operating at 1GHz–3GHz.

Racetrack microring resonator with improved quality factor based on asymmetric waveguide bend

Racetrack microring resonators with improved quality factors based on asymmetric Bezier waveguide bend for silicon nitride photonics integration platform have been proposed and demonstrated experimentally in this paper. The asymmetric Bezier waveguide bend can reduce bend loss which is one of the major limitations of the Q factor of racetrack microring resonators. The proposed racetrack microring resonator structure based on an asymmetric Bezier bend waveguide can significantly improve the Q factor while maintaining the same device area. Such racetrack microring resonators with superior performance can help improve the performance of on-chip devices and further promote the development of a photonic integration platform.

Use of Cannabis and Cannabinoids for Treatment of Cancer.

Simple SummaryCancer is a disease which affects approximately 40% of people in their lifetime. Chemotherapy, the primary choice for treatment of cancer, is often ineffective or/and presents itself with many debilitating side effects, including loss of appetite, nausea, insomnia, and anxiety. Components of cannabis extracts, including cannabinoids and terpenes, may present an alternative for controlling side effects and may be used for tumor shrinkage together with chemodrugs. Cannabinoids act on so called endocannabinoid system (ECS) that operates in our body to maintain homeostasis. ECS promotes healthy development of tissues and regulates many processes in our organism and when disbalanced may lead to disease, including cancer. In this review, we will discuss the role of the ECS in relation with carcinogenesis and use of cannabis extracts and their components for primary and secondary care of cancer. Knowledge about the use of cannabinoids for cancer therapy may prolong the life of many cancer patients.The endocannabinoid system (ECS) is an ancient homeostasis mechanism operating from embryonic stages to adulthood. It controls the growth and development of many cells and cell lineages. Dysregulation of the components of the ECS may result in uncontrolled proliferation, adhesion, invasion, inhibition of apoptosis and increased vascularization, leading to the development of various malignancies. Cancer is the disease of uncontrolled cell division. In this review, we will discuss whether the changes to the ECS are a cause or a consequence of malignization and whether different tissues react differently to changes in the ECS. We will discuss the potential use of cannabinoids for treatment of cancer, focusing on primary outcome/care—tumor shrinkage and eradication, as well as secondary outcome/palliative care—improvement of life quality, including pain, appetite, sleep, and many more factors. Finally, we will complete this review with the chapter on sex- and gender-specific differences in ECS and response to cannabinoids, and equality of the access to treatments with cannabinoids.

Effects of different Bismuth concentrations of InSbBi crystals grown by Bridgman technique

InSb1-xBix (x = 0, 0.005, 0.010, 0.015) crystals are grown by vertical Bridgman technique using single-zone resistive heating furnace. The main objective of this paper is to study the improvement of thermoelectric quality factors by different concentrations of Bismuth (Bi) in InSbBi crystals. EDAX (Energy Dispersive Analysis of X-rays) confirms that the grown crystals are pure and show the presence of In, Sb, and Bi in proportion. Powder X-ray diffractogram confirms the cubic zinc blend structure of these crystals with space group F-43m and all the diffraction peaks are matched well to the standard JCPDS-ICDD No. 6-0208. Raman spectra are recorded from 80 K to 300 K and Raman mapping spectra at room temperature for all above crystals have shown the presence of TO mode at 179.91 cm−1 and LO mode at 190.16 cm−1. The sharpness and intensity of Raman spectra have clearly reflected the purity and quality of the grown crystals. The electrical conductivity σ is found to increase slowly upto 450 K and then increases linearly upto 600 K and above that, it gets saturated in all crystals. The Seebeck coefficient remains negative showing that these crystals are n-type semiconductor and its value is found to be increased to −200 μV/K for InSb0.985Bi0.015 in comparison to −150 μV/K for pure InSb near 600 K. From the lattice thermal conductivity, power factor and thermoelectric figure of merit i.e. ZT calculations, it is concluded that InSb0.985Bi0.015 at 670 K gives the highest value of ZT = 0.45 in comparison to other grown crystals.

Thermoelastic damping suppression method of micro-beam resonators with basically constant resonant frequency

High-Q micro-beam resonators have been widely applied in communication fields such as narrowband filters, but thermoelastic damping restricts the further improvement of quality factor. Traditional method such as overall size optimization used for thermoelastic quality factor (Q TED) improvement will cause the resonant frequency of the resonator change greatly, which will not be allowed in narrowband filters. In this article, three slots are introduced into a beam resonator to greatly reduce the thermoelastic damping by rationally arranging the length ratio of the central slot and the side slot, while the resonant frequency is basically kept unchanged. The feasibility is verified by parametric finite element simulation method. The results indicate that without changing the overall size of the micro-beam resonator, the resonant frequency remains unchanged and the Q TED of the resonator can be doubled over twice both in the isothermal region and adiabatic region by placing side slots of 10% and a central slot of 30%. The proposed thermoelastic damping suppression method shows potential applicability for MEMS resonators in high-order mode of vibration.

High-temperature Pt–Al2O3 composite nano-thick interdigital electrodes for surface acoustic wave sensors

High-temperature stability of ultra-thin film electrodes is vital for surface acoustic wave (SAW) devices in harsh environments. This paper proposed the Pt–Al2O3 composite Nano-thick interdigital electrodes (IDEs) for langasite-based high-temperature SAW sensors. The sandwich structure of the IDEs was composed of Pt layers and Al2O3 armors. The armor consisting of barrier and coating layers was introduced to reduce the agglomeration, oxidation, and interdiffusion of IDEs at high temperatures. Capacitive bonding pads were proposed to transmit radiofrequency signals through the closed armor. The composite IDEs (226 nm thickness) had good structural stability and impurities concentration less than 1% at 1000 °C (3 h, air condition). Improved quality factors of 8805, and matched electrical impedance of 51 Ω and −16° were achieved through the electroacoustic optimized IDEs. Finally, multiple SAW temperature sensors using the composite IDEs presented fitting errors less than 1% and hysteresis errors below 4% in 80–1000 °C exceeded 9 h, which was 150 °C higher than existing ones. The proposed composite IDEs enable SAW devices to be applicated in 80–1000 °C.

Implementing High Q-Factor HTS Resonators to Enhance Probe Sensitivity in 13C NMR Spectroscopy

Nuclear magnetic resonance spectroscopy (NMR) probes using thin-film high temperature superconducting (HTS) resonators provide exceptional mass sensitivity in small-sample NMR experiments for natural products chemistry and metabolomics. We report improvements in sensitivity to our 1.5 mm 13C-optimized NMR probe based on HTS resonators. The probe has a sample volume of 35 microliters and operates in a 14.1 T magnet. The probe also features HTS resonators for 1H transmission and detection and the 2H lock. The probe utilizes a 13C resonator design that provides greater efficiency than our previous design. The quality factor of the new resonator in the 14.1 T background field was measured to be 4,300, which is over 3x the value of the previous design. To effectively implement the improved quality factor, we demonstrate the effect of adding a shorted transmission line stub to increase the bandwidth and reduce the rise/fall time of 13C irradiation pulses. Initial NMR measurements verify 13C NMR sensitivity is significantly improved while preserving detection bandwidth. The probe will be used for applications in metabolomics.

Piezoelectric acoustic wave characteristics of Pb(In0.5Nb0.5)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal substrate: A comparative study with and without SiO2 overlay

This paper investigates the excitation and propagation characteristics of a piezoelectric acoustic wave propagating in a rotated Y-cut X-propagating Pb(In0.5Nb0.5)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) relaxor-based ferroelectric single crystal substrate. Numerical simulations were performed to evaluate the acoustic wave properties by FEM software COMSOL. For comparison, two types of structures are taken into consideration: one is the traditional metal electrode/YX-PIN-PMN-PT and the other is silicon dioxide (SiO2) overlay/metal electrode/YX-PIN-PMN-PT substrate. It is shown that shear-horizontal (SH)-type piezoelectric boundary acoustic waves (PBAW) exist in the SiO2 overlay/metal electrode/YX-PIN-PMN-PT substrate and offer a fairly large electromechanical coupling factor K2 of 30%. Compared to a surface acoustic wave excited in the metal electrode/YX-PIN-PMN-PT substrate, enlarged phase velocity and significantly improved quality factor (∼3500) are simultaneously obtained for SH-type PBAW, which are promising for electromechanical transducer applications with high performance.

Magnetic Core TSV-Inductor Design and Optimization for On-chip DC-DC Converter

The conventional on-chip spiral inductor consumes a significant top-metal routing area, thereby preventing its popularity in many on-chip applications. Recently through-silicon-via– (TSV) based inductor (also known as a TSV-inductor) with a magnetic core has been proved to be a viable option for the on-chip DC-DC converter. The operating conditions of these inductors play a major role in maximizing the performance and efficiency of the DC-DC converter. However, there is a critical need to study the design and optimization details of magnetic core TSV-inductors with the unique three-dimensional structure embedding magnetic core. This article aims to provide a clear understanding of the modeling details of a magnetic core TSV-inductor and a design and optimization methodology to assist efficient inductor design. Moreover, a machine learning–assisted model combining physical details and artificial neural network is also proposed to extract the equivalent circuit to further facilitate DC-DC converter design. Experimental results show that the optimized TSV-inductor with the magnetic core and air-gap can achieve inductance density improvement of up to 7.7 \( \times \) and quality factor improvements of up to 1.6 \( \times \) for the same footprint compared with the TSV-inductor without a magnetic core. For on-chip DC-DC converter applications, the converter efficiency can be improved by up to 15.9% and 6.8% compared with the conventional spiral and TSV-inductor without magnetic core, respectively.

Cascaded nanobeam spectrometer with high resolution and scalability

An on-chip reconstruction spectrometer provides a powerful approach for miniaturized and portable applications. Owing to the cross-correlation and line shape of broadband responses, the reconstruction spectrometer exhibits limited resolution and a fixed bandwidth. Here we demonstrate a cascaded nanobeam spectrometer with assistance of a reconstruction algorithm. The transmissions of tunable Fano-enhanced nanobeams (FENs) are of good orthogonality and have improved quality factors. We retrieved a narrowband signal of 0.16 nm linewidth and a dual peak at 0.32 nm distance for resolution characterization. This result breaks the limit of the full width at half maximum for narrowband filter spectrometers. An expanded bandwidth is realized by a three-channel cascaded device, and signal spectra in the 16 nm range are reconstructed successfully. Each FEN unit has an ultra-compact footprint of 18 × 18 µ m 2 . In view of the improved performance and flexibility, our concept is an ideal candidate for precise and miniaturized applications.

A wide band gap phononic crystal strip for quality factor improvement in a length extensional mode MEMS resonator

A wide band gap phononic crystal strip for quality factor improvement in a length extensional mode MEMS resonator

Atomically Smooth Single-Crystalline Platform for Low-Loss Plasmonic Nanocavities.

Nanoparticle-on-mirror plasmonic nanocavities, capable of extreme optical confinement and enhancement, have triggered state-of-the-art progress in nanophotonics and development of applications in enhanced spectroscopies. However, the optical quality factor and thus performance of these nanoconstructs are undermined by the granular polycrystalline metal films (especially when they are optically thin) used as a mirror. Here, we report an atomically smooth single-crystalline platform for low-loss nanocavities using chemically synthesized gold microflakes as a mirror. Nanocavities constructed using gold nanorods on such microflakes exhibit a rich structure of plasmonic modes, which are highly sensitive to the thickness of optically thin (down to ∼15 nm) microflakes. The microflakes endow nanocavities with significantly improved quality factor (∼2 times) and scattering intensity (∼3 times) compared with their counterparts based on deposited films. The developed low-loss nanocavities further allow for the integration with a mature platform of fiber optics, opening opportunities for realizing nanocavity-based miniaturized photonic devices for practical applications.

E-learning and COVID-19: Predicting Student Academic Performance Using Data Mining Algorithms

The satisfaction of E-learners has the main effect on the success of the E-learning process and leads to improvements in the E-learning system's quality and several factors affect this satisfaction. Based on the dimensions of e-learning, the main objective of this study was to evaluate the factors that contributed to students' satisfaction with e-learning during pandemic the Covid-19 and to give a thorough understanding and knowledge of different data mining techniques that have been used to predict student performance and development, as well as how these techniques help in the identification of the most relevant student attribute for prediction. Currently, to search for information in large databases, data mining techniques have become very popular and proven itis effective. Because of the performance and effectiveness of data mining techniques, it has been adopted by many areas such as telecommunication, education, sales management, banking, etc. In this paper, data mining algorithms were relied on to build e-learning classification models for a "student performance" data set, the proposed model includes 1000 instances with 35 attributes. Data mining algorithms have been implemented on the student performance data set in E-learning. Among these algorithms are the Decision Tree algorithm, Random Tree algorithm, Naive Bayes algorithm, Random Forest algorithm, REP Tree algorithm, Bagging algorithm and KNN algorithm. After comparing the results and conducting the assessment, the impact of the proposed features in e-learning on the student's performance was clarified. The final result of this study is important for providing greater insight into evaluating student performance in the COVID-19 pandemic and underscores the importance of data mining in education.

Figure of Merit Enhancement of Laterally Vibrating RF-MEMS Resonators via Energy-Preserving Addendum Frame.

This paper examines a new technique to improve the figure of merit of laterally vibrating RF-MEMS resonators through an energy-preserving suspended addendum frame structure using finite element analysis. The proposed suspended addendum frame on the sides of the resonant plate helps as a mechanical vibration isolator from the supporting substrate. This enables the resonator to have a low acoustic energy loss, resulting in a higher quality factor. The simulated attenuation characteristics of the suspended addendum frame are up to an order of magnitude larger than those achieved with the conventional structure. Even though the deployed technique does not have a significant impact on increasing the effective electromechanical coupling coefficient, due to a gigantic improvement in the unloaded quality factor, from 4106 to 51,136, the resonator with the suspended frame achieved an 11-folds improvement in the figure of merit compared to that of the conventional resonator. Moreover, the insertion loss was improved from 5 dB down to a value as low as 0.7 dB. Furthermore, a method of suppressing spurious mode is demonstrated to remove the one incurred by the reflected waves due to the proposed energy-preserving structure.

3D-Printed Dielectric Resonators for Quasi-TE112 Mode Singlets, Doublets and Dual-Mode Filters

This paper demonstrates the use of a ceramic-based stereolithography additive manufacturing process in the fabrication of higher-order mode dielectric resonators. In this work, dielectric resonators with concentric disks around a combline rod structure are 3D-printed using alumina. The integration of the concentric disks for use of the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">112</sub> mode allows for a more compact cavity structure and a higher unloaded quality factor when compared to a simple dielectric combline resonator with a similar S-parameter response. The achievable improvements in quality factor for the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">112</sub> -mode resonators utilising concentric disks are compared through simulations and experimental results. The measured results demonstrate an increased average in the unloaded quality factor of Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>u</i></sub> ≈ 2172 which is approximately 44%. Additionally, the application of the 3D-printed resonators is further demonstrated in a TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">112</sub> singlet, doublet, and dual-mode filter configuration.

Design considerations of III-nitride-based two-dimensional photonic crystal cavities with crystallographically induced disorder

We present a study on the improvement of quality factors (Q-factors) of III-nitride-based two-dimensional photonic crystal (2D-PhC) nanocavities. Although III-nitride-based 2D-PhC cavities have been studied for long time, they typically show relatively low experimental Q-factors due to disorders inevitably introduced during the fabrication processes. In order to realize high-Q-factors, it is necessary to introduce cavities that are tolerant to disorder. We numerically reproduce the experimental found disorder in simulations, and discuss the influence of disorder on Q-factors of several types of cavities. We demonstrate the suitability of these cavities for the realization of high-Q-factors, and show which structures have the largest tolerance for disorders.

A low‐noise current‐reused CMOS active inductor by exploiting G m ‐boosting technique

This work introduces a new low-noise current-reused CMOS active inductor (AI) based on Gyrator-C configuration. In the proposed AI, a simple common-source amplifier is utilised for boosting effective Gm and improving noise performance of the AI. While the Gm-boosting technique improves the noise performance as well as the quality factor of the inductor, a resistor is also added to the feedback path for more quality factor improvement. Rigorous analysis of the proposed circuit shows a significant noise performance and quality factor enhancement. In order to verify the concept and confirm the mathematical analysis, the AI is designed and simulated in a commercial 0.18 μm RF-CMOS technology. The simulation results show that the proposed inductor operates in 1 to 7.2 GHz frequency range, has a 9 nH inductance at 2.864 GHz frequency and 650 μW total power dissipation at 1.8-V supply voltage. Maximum quality factor of 90 is achieved at 2.864 GHz frequency and a quality factor greater than 40 is obtained from 2.4 to 3.3 GHz. The input-referred current noise of the proposed inductor is as low as 22 pA / √ Hz showing 30.5% improvement compared to the conventional AI. The proposed AI is also tunable and sweeping the tuning voltage results in changing extracted inductance from 4.35 to 15.2 nH with only a chip area of 0.003 mm2. Post-layout and different Monte Carlo simulation results also confirm the robust operation of the proposed AI against different process non-idealities.

Impact of soil treatment with alkaline zinc carbonate on the quantity and quality of maize (Zea mays L.) yield

Our research conducted at the Department of Soil Management was aimed at investigating whether maize (Zea mays L.) would respond to a supply of zinc as a micro-element. We expected an increased yield and/or improvements in certain quality factors, such as a greater oil and starch contents. Soil fertilization experiments were performed with a basic zinc-carbonate active agent, under field conditions, in brown forest soil with clay illuviation, in a random block arrangement. Four iterations of the experiments were done in the vicinity of Zimány village in South-West Hungary. Maize served as our test crop. In 2010 we tested the first-year impact of the active agent, while in 2011 we evaluated its retard effect. In 2010 each of the examined quality attributes showed most improvement in response to the 100 kg ha-1 treatment, which corresponded to the largest dose applied in the study. Out of the examined yield elements the average values of the cob mass and the unfertilized cob length were greatest in 2011, because of the 25 kg ha-1 treatment, the lowest dose in the experiment, while with respect to the grain/cob ratio the 50 kg ha-1 treatment was found the most effective.