Search

A bound state in the continuum (BIC) metasurface (MS) was designed to achieve an ultrahigh quality factor(Q factor) using natural hyperbolic materials, such as hexagonal boron nitride. To investigate the structure's dispersion and Q factor, a unit cell of the MS comprising semicircles and rectangles was designed. This MS structure supports symmetry-protected BICs and exhibits a Q factor of approximately 13 000 at 4.43964 × 1013 Hz. By breaking the MS symmetry, the BICs are converted into quasi-BICs, resulting in quasi-BIC resonance with a high Q factor. Further analysis of the reflection spectra and multipole theory indicates that the toroidal dipole (TD) has the most significant influence on the resonance. Thus, the symmetry-protected BIC can be transformed into the TD resonance with a Q factor by breaking symmetry. [ABSTRACT FROM AUTHOR]

We present a model to calculate the resonant energy absorption of a laser with finite number of pulses impinging on a doped porous dielectric slab. Analytical reflection R and transmission T coefficients are first derived as a function of 0 < α ≤ 1 to account for porosity with α = 1 denotes a perfect ideal slab, which are verified using an electromagnetic solver. Based on the Drude model with resonant line due to impurities, we calculate the resonant energy absorption as a function of doping concentration, quality factor of the resonant line, porosity, length of the slab, and laser pulse length. It is important to note that simulating the combined effects of these parameters is challenging using existing models. The energy absorption efficiency is maximized for a certain degree of doping concentration at a given pulse length and also for a certain pulse length at a given doping concentration. At small doping concentration, the absorption efficiency increases with smaller α (high porosity) and the trend is reversed at larger α (low porosity). Dimensionless parameters are constructed, allowing the calculated results to be applicable over a wide range of frequencies and pulse durations. Thus, this model serves as a useful tool to characterize the amount of energy absorption due to these combined effects, which are important for many applications in plasmonics, optoelectronics, high power microwaves breakdown, and organic materials. Some possible experiments are suggested for future verification of the model. [ABSTRACT FROM AUTHOR]

A highly sensitive terahertz stereo metasurface sensor, characterized by a high quality factor (Q-factor) and based on dual toroidal dipole (TD) resonance, has been proposed. The optimal structural parameters are ascertained by comparing the pertinent parameters of the stereo and planar structures in relation to TD modal excitation. The effective excitation of the TD mode is demonstrated using the calculations of multipole scattered power, reflection spectra, surface currents, electric fields, and magnetic field distributions. It is crucial that the stereo metasurface exhibits simplicity and that the dual TD resonance can be readily excited through simple adjustments in the distance and height of the intermediate gap. It also demonstrates exceptionally high sensitivity and Q-factor, both of which are essential for sensing applications. Moreover, the proposed stereo terahertz metasurface sensor still shows excellent sensing performance in a wide range of incidence angles (±40°), which is of great significance for practical applications. In conclusion, this structure offers a novel design framework for high-performance terahertz sensors based on the TD mode. [ABSTRACT FROM AUTHOR]

This study investigates the use of atomic layer deposition (ALD) to mitigate multipacting phenomena inside superconducting radio frequency cavities used in particle accelerators while preserving high quality factors in the 1010 range. The unique ALD capability to control the film thickness down to the atomic level on arbitrary complex shape objects enables the fine-tuning of TiN film resistivity and total electron emission yield (TEEY) from coupons to devices. This level of control allows us to adequately choose a TiN film thickness that provides both high resistivity to prevent Ohmic losses and a low TEEY to mitigate multipacting for the application of interest. The methodology presented in this work can be scaled to other domains and devices subject to RF fields in vacuum and sensitive to multipacting or electron discharge processes with their own requirements in resistivities and TEEY values. [ABSTRACT FROM AUTHOR]

This study investigates the influence of trimming layer thickness on the performance characteristics of thin-film bulk acoustic resonators (FBARs). By adjusting the thickness of the trimming layer, we aimed to optimize the resonant (f s) and antiresonant frequencies (f p) , which are critical for the filter's performance in blocking or passing specific frequency bands. Employing theoretical modeling and experimental validation, we explored how variations in the trimming layer thickness affect the electromechanical coupling coefficient (k t 2) and the overall energy efficiency of FBARs. The study also considered the impact of piezoelectric layer thickness on the effectiveness of these adjustments, revealing that thinner piezoelectric layers are more sensitive to changes in the trimming layer, enhancing the tuning capability for high-frequency applications. Our results confirm that reducing the trimming layer thickness increases both resonant and antiresonant frequencies, with a more pronounced effect on the latter, suggesting a significant phase correction effect from the trimming layer, resulting in the quality Q factor reductions. Our experimental results show that as the trimming layer thickness increases from 200 to 300 nm, the Q factor increases by 11%, while k t 2 decreases by 4%. This research provides critical insights into the design and optimization of FBARs, offering guidelines that can help advance the development of more efficient and effective RF components for future mobile communication technologies. [ABSTRACT FROM AUTHOR]

The optical behavior of the square lattices of the hemispherical nanovoids on the surface of the high-refractive-index all-dielectric slabs in the visible range is studied numerically using gallium phosphide as an example. There exist Fano resonances for these metasurfaces for a limited range of thicknesses. The Fano resonances are caused by the interference between the Mie-type scattering resonances of surface pattern elements and the Fabry–Pérot modes of the slabs. The maximum enhancements of the optical Kerr nonlinearity with respect to the bulk material are revealed at the Fano resonances, in particular, for the thinnest nanostructures. Interestingly, no positive correlation between the quality factor and the enhancement of the optical Kerr effect of the metasurface at the Fano resonances is observed. [ABSTRACT FROM AUTHOR]

Phase separation of biomolecules can facilitate their spatiotemporally regulated self-assembly within living cells. Due to the selective yet dynamic exchange of biomolecules across condensate interfaces, condensates can function as reactive hubs by concentrating enzymatic components for faster kinetics. The principles governing this dynamic exchange between condensate phases, however, are poorly understood. In this work, we systematically investigate the influence of client–sticker interactions on the exchange dynamics of protein molecules across condensate interfaces. We show that increasing affinity between a model protein scaffold and its client molecules causes the exchange of protein chains between the dilute and dense phases to slow down and that beyond a threshold interaction strength, this slowdown in exchange becomes substantial. Investigating the impact of interaction symmetry, we found that chain exchange dynamics are also considerably slower when client molecules interact equally with different sticky residues in the protein. The slowdown of exchange is due to a sequestration effect, by which there are fewer unbound stickers available at the interface to which dilute phase chains may attach. These findings highlight the fundamental connection between client–scaffold interaction networks and condensate exchange dynamics. [ABSTRACT FROM AUTHOR]

We investigate the effect of a cavity on nonlinear two-photon transitions of a molecular system and we analyze how such an effect depends on the cavity quality factor, the field enhancement, and the possibility of dephasing. We find that the molecular response to strong light fields in a cavity with a variable quality factor can be understood as arising from a balance between (i) the ability of the cavity to enhance the field of an external probe and promote multiphoton transitions more easily and (ii) the fact that the strict selection rules on multiphoton transitions in a cavity support only one resonant frequency within the excitation range. Although our simulations use a classical level description of the radiation field (i.e., we solve Maxwell–Bloch or Maxwell–Liouville equations within the Ehrenfest approximation for the field–molecule interaction), based on experience with this level of approximation in the past studies of plasmonic and polaritonic systems, we believe that our results are valid over a wide range of external probing. [ABSTRACT FROM AUTHOR]

Phonons confined in mechanical resonators can be coupled to a variety of quantum systems and are expected to be applied to hybrid quantum systems. Diamond surface acoustic wave (SAW) devices are capable of high efficiency in phonon interaction with color centers in diamond. The temperature dependence of the quality factor is crucial for inferring the governing mechanism of coupling efficiency between phonons and color centers in diamond. In this paper, we report on the temperature dependence of the quality factor of an AlN/diamond SAW device from room temperature to 5 K. The temperature dependence of the quality factor and resonant frequency suggests that the mechanism of SAW dissipation in the AlN/diamond SAW resonator at 5 GHz is the phonon–phonon scattering in the Akheiser regime and that further cooling can be expected to improve the quality factor. This result provides a crucial guideline for the future design of AlN/diamond SAW devices. [ABSTRACT FROM AUTHOR]

This paper proposes an interpretation methodology for the effect of transient process data on quality of injection molded parts. The transient process data measured in the actual processing space have been regarded as the most relevant information to manufacturing processes and product quality. However, its interpretation to pinpoint which feature in the data would affect part quality has traditionally relied on knowledge and understanding of the manufacturing process. The main objective of this method is to reduce the dependency of the transient process data analysis on process knowledge and understanding by using explainable artificial intelligence (XAI). The contribution of the 'section-wise' features in the transient process data to the quality prediction of machine learning (ML) models was investigated for the first time. The interpretation results of the effect of cavity pressure and mold surface temperature on four different quality factors represented reasonable explanations of the characteristics of the polymer materials, product geometry, and molding process. Due to the intermediate relationship of the transient process data with the user-specified process parameters and the resulting quality variables, the interpretation results can be further utilized to optimize the process and provide the optimal transient process data profile for best part quality. [ABSTRACT FROM AUTHOR]

The hybrid system consisting of microwave photons and ferromagnetic magnons has been studied in the context of quantum sensing and quantum manipulation of magnons. We demonstrate a strong coupling between magnons and photons in a dielectric resonator with a large dielectric constant and high quality factor. The coupling rate between magnons and photons amounts to g / 2 π = 126 MHz, and the corresponding cooperativity reaches C = 1.09 × 10 6 at cryogenic temperature. The high cooperativity is mainly due to the small internal decay rate of the resonator, which is advantageous for various quantum magnonics experiments. [ABSTRACT FROM AUTHOR]

We examine the impact of corporate financialization on export product quality using data from Chinese A-share listed companies from 2000 to 2015. Our findings indicate that corporate financialization inhibits the upgrading of export product quality through ‘innovation crowding out’ and ‘factor substitution’ effects. Heterogeneity tests reveal that this negative effect is pronounced for firms with strong motivations for market arbitrage, precautionary savings, tunneling, as well as higher managerial overconfidence. Additionally, firms exporting to high-income countries, engaging in general trade in less digitally developed regions, and adopting compensation incentives are more susceptible to the disincentive effects of corporate financialization on export product quality. [ABSTRACT FROM AUTHOR]

Metamaterials based on quasi‐bound states in the continuum (qBICs) with manipulable resonance quality (Q) factors have provided a standout platform for cutting‐edge terahertz (THz) sensing applications. However, most so far have been implemented as conventional metal patch structures with adjacent substrate layers, incurring the limitation of insufficient light‐matter interaction due to substrate effects. Here, qBIC‐driven metamaterials with substrate‐free metallic aperture structures for tailoring light‐matter interactions and exhibiting near‐ideal sensing performance is introduced. Specifically, it is incorporated ultrafast femtosecond laser processing technology to fabricate H‐type metallic aperture metamaterials with accessible high‐contrast Q factor resonances allowed by in‐plane symmetry breaking. Correspondingly, stronger light field energies are applied to the interactions due to completely eliminating the confinement of the substrate effect, enabling experimental sensitivity of up to 0.86 THz RIU−1 for the qBIC resonance, 1.9 times that of the conventional dipole resonance. Moreover, a high Q qBIC resonance achieved by optimized asymmetry parameter is exploited for detecting ultrathin layers of L‐proline molecules as low as 0.87 nmol. It is envisioned that this approach will deliver insights for real‐time, precise, and high‐performance detection of trace biomolecules, and open new perspectives for realizing ideal performance metadevices. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) have recently emerged as a promising technology for efficient water wave energy harvesting. However, there is a paucity of clear guidance regarding the optimal designs of TENGs and their shells to achieve efficient absorption and conversion of water wave energy in real random waves. Herein, from the perspective of wave‐body interaction and energy transfer, this paper proposes a structural quality factor (Qunit) for the quantitative evaluation of both the motion of floating triboelectric nanogenerator (Flo‐TENG) shells and their capability to absorb and convert water wave energy efficiently. The factor is further subdivided into the amplitude structural quality factor (Qacc), which characterizes shell motion amplitude, and the frequency structural quality factor (Qf), which describes shell motion frequency. This paper systematically investigates the impact of various shell parameters such as bow shapes, curvatures, inclinations, and immersion ratios on Qacc and Qf. The findings indicate that variations in shell shape result in distinct Qunit values along different axial directions of wave propagation. These variations directly influence energy absorption efficiency in these directions. These results provide fundamental guidance for the design of high‐performance Flo‐TENG shells and the selection of internal energy harvesting directions to enable more efficient energy conversion. [ABSTRACT FROM AUTHOR]

In this work, an experimental study supported by numerical modeling that demonstrates the possibility of exciting Symmetry Protected‐Bound states In the Continuum (SP‐BICs) in a 1D silicon grating fabricated on a lithium niobate substrate is presented. bBoth transverse electric and magnetic polarization states are investigated, leading to the excitation of four quasi‐ Bound states In the Continuum (quasi‐BIC) resonances, exhibiting distinct behaviors. Under standard illumination conditions (plane of incidence perpendicular to the 1D grating lines), two of these resonances are highly sensitive to illumination conditions, while the other two resonances involving unconventional illumination directions (plane of incidence parallel to the grating lines) are more robust to the angle of incidence, but just as sensitive to external stresses in terms of resonance wavelength and quality factor. Additionally, temperature detection is experimentally demonstrated with a Sensitivity of ST = 0.81∼nm °C−1, a state‐of‐the‐art value achieved due to significant electromagnetic field enhancement inside the lithium niobate substrate at the quasi‐BIC resonance. These findings pave the way for their use in various sensing applications (such as biology, electromagnetic, and temperature sensing), as well as nonlinear applications like second harmonic generation, and electro‐ and acousto‐optic modulation. [ABSTRACT FROM AUTHOR]

We study transits of several 'hot Jupiter' systems, including WASP-12 b, WASP-43 b, WASP-103 b, HAT-P-23 b, KELT-16 b, WD 1856+534 b, and WTS-2 b, with the goal of detecting tidal orbital decay and extending the baselines of transit times. We find no evidence of orbital decay in any of the observed systems except for that of the extensively studied WASP-12 b. Although the orbit of WASP-12 b is unequivocally decaying, we find no evidence for acceleration of said orbital decay, with measured |$\ddot{P} = (-7 \pm 8) \times 10^{-14} \, \rm s^{-1}$|⁠ , against the expected acceleration decay of |$\ddot{P} \approx -10^{-23} \, \rm s^{-1}$|⁠. In the case of WD 1856+534 b, there is a tentative detection of orbital growth with |$\dot{P} = (5.0 \pm 1.5) \times 10^{-10}$|⁠. While statistically significant, we err on the side of caution and wait for longer follow-up observations to consider the measured |$\dot{P}$| real. For most systems, we provide a 95 per cent confidence lower limit on the tidal quality factor, |$Q_\star ^{\prime }$|⁠. The possibility of detecting orbital decay in hot Jupiters via long-term radial velocity (RV) measurements is also explored. We find that |${\sim} 1 \rm \, m \, s^{-1}$| precision in RVs will be required to detect orbital decay of WASP-12 b with only 3 yr of observations. Currently available RV measurements and precision are unable to detect orbital decay in any of the systems studied here. [ABSTRACT FROM AUTHOR]

In order to solve the problem of signal delay, a novel low-K Ca 3 Cr 2 Ge 3 O 12 ceramic for 5G and millimeter-wave communication was prepared by a solid-state reaction method. XRD and Rietveld refinement results confirm that it belongs to the garnet structure with the Ia-3d space group. The shrinkage rate of the sample sintered at 1350 °C reached 11.9 %, and the relative density exceeded 94.3 %. Excellent microwave dielectric properties were obtained. The permittivity was 8.38, the quality factor was 23,107 GHz, and the temperature coefficient of resonant frequency was −43.57 ppm/°C. The relationship between the crystal structure and microwave dielectric properties of ceramics was further studied. The results show that lattice vibration, stacking fraction and bond strength have a great influence on the Q × f value of ceramics, and the bond valence parameter is the key factor affecting the temperature stability. In addition, the theoretical quality factor of the ceramic can reach ∼13,0000 GHz by far-infrared reflection spectroscopy, and the ceramic has great research potential. The development of Ca 3 Cr 2 Ge 3 O 12 ceramics and the study of microwave dielectric properties have filled the research gap of related systems. The excellent microwave dielectric properties indicate that it can be used as an alternative material for the preparation of components in the field of communication. [ABSTRACT FROM AUTHOR]

Two series of LiF-doped Li 4 CaSr(SiO 4) 2 (LCSS) ceramics with different LiF contents were synthesized by SSR and RS methods. The formation of single-phase LCSS + x wt% LiF (x = 0–4, SSR) (LCSSL 04) and LCSS + y wt% LiF (y = 0–8, RS) (LCSSF 08)ceramics with an orthorhombic structure (Pbcm space group) was confirmed by the Rietveld refinement of their XRD data. The addition of LiF improved the relative density and microwave dielectric properties of LCSS + x wt% LiF (0 < x ≤ 2, SSR) and LCSS + y wt% LiF (0 < y ≤ 3, RS). The LCSS +2 wt% LiF (SSR) ceramic exhibited good properties, presenting a dielectric permittivity (ε r) of 7.03, quality factor (Q × f) of 62,195 GHz (at 11.6 GHz), and temperature coefficient of resonant frequency (τ f) of −76 ppm/°C. Further, the LCSS +3 wt% LiF (RS) ceramic exhibited outstanding performances, with an ε r of 6.1, Q × f of 103,086 GHz (at 15.8 GHz), and τ f of −67 ppm/°C. The chemical compatibility with silver suggests that both of them are potential candidates for low temperature co-fired ceramic (LTCC) devices. [ABSTRACT FROM AUTHOR]

Diamond has superlative material properties for a broad range of quantum and electronic technologies. However, heteroepitaxial growth of single crystal diamond remains limited, impeding integration and evolution of diamond-based technologies. Here, we directly bond single-crystal diamond membranes to a wide variety of materials including silicon, fused silica, sapphire, thermal oxide, and lithium niobate. Our bonding process combines customized membrane synthesis, transfer, and dry surface functionalization, allowing for minimal contamination while providing pathways for near unity yield and scalability. We generate bonded crystalline membranes with thickness as low as 10 nm, sub-nm interfacial regions, and nanometer-scale thickness variability over 200 by 200 μm2 areas. We measure spin coherence times T2 for nitrogen vacancy centers in 150 nm-thick bonded membranes of up to 623 ± 21 μs, suitable for advanced quantum applications. We demonstrate multiple methods for integrating high quality factor nanophotonic cavities with the diamond heterostructures, highlighting the platform versatility in quantum photonic applications. Furthermore, we show that our ultra-thin diamond membranes are compatible with total internal reflection fluorescence (TIRF) microscopy, which enables interfacing coherent diamond quantum sensors with living cells while rejecting unwanted background luminescence. The processes demonstrated herein provide a full toolkit to synthesize heterogeneous diamond-based hybrid systems for quantum and electronic technologies. Development of diamond-based quantum and electronic technologies requires heterogeneous integration, which has remained challenging. This work realizes direct bonding of single crystal diamond membranes to a broad range of technology-relevant substrates while maintaining quantum coherence for hosted qubits. [ABSTRACT FROM AUTHOR]

Interest in flexible photonics has been motivated by the development of artificial smart skins. In particular, coupling of photonics and mechanics can offer opportunities to realize ultrasensitive strain sensor, however, low‐cost fabrication of flexible sensing device with desired photonic functionality remains a challenge. Hereby, the study reports an ultrasensitive strain‐gauge sensor based on the poly(ethylenenaphthalate (PEN))/monocrystal Au/MgF2/CsPbBr3 nanorod/Al2O3/polyacrylonitrile (in short P/mAu/M/CPB@Al2O3@PAN), which are sensitive to nanoscale structure alterations of PEN substrate via the stress response of the single‐mode laser based on the piezoelectric‐effect. Wherein a low‐threshold single‐mode lasing (Pth ≈ 170 nJ cm−2) is achieved through coating Al2O3 on the CsPbBr3 nanorod, producing the higher quality factor (Q ≈ 1637) to guarantee a much higher sensitivity in sensing application. Reversible spectral regulating of ≈3 nm in single‐mode‐lasing wavelength, with a subnanometre scale resolution <0.4 nm and the wavelength sensitivity (Sλ) as high as 160 nm RIU−1, is validated in response to applied strain ranging from −1.31% to 1.31%. This work not only represents essential progress in construction of ultrasensitive and cost‐effective flexible photonic sensor, but also lays the foundation for the potential application in smart photonic skins. [ABSTRACT FROM AUTHOR]

In this paper, a plasmonic filter is realized which consists of a T-shaped stub resonator and two side-coupled rectangular cavities; forming an inverted E-type structure connected to the main waveguide. Initially, the device is investigated for the function of a band stop filter in the telecommunication band. Later, the proposed device is investigated for bandpass filtering application by using Vanadium dioxide as an active material to show the improvement in transmittance, modulation depth, quality factor, and tunability of the device. Vanadium dioxide is filled into all four arms of the inverted E shaped structure. For the OFF-state, the electric field is applied to the T shape structure which are; arm 2 and arm 4 whereas for the ON-state, the electric field is applied to the two-side coupled rectangular cavities named as arm 1 and arm 3. The device has shown its potential application in high-quality factor filtering, switching, and modulation applications in telecommunication bands. The quality factor of 208 and 138.18 is achieved for ON-state and OFF-state respectively, whereas the quality factor is further increased and a high value of 308 is obtained by optimizing the device parameters. An extension ratio of modulation of 18.45 dB is attained which can be further increased to 19.95 dB by changing the width of the cavities. Device optimization is performed to show that the bandwidth and transmittance of the spectrum can be manipulated by changing the device parameters like width, length, and height of the cavities. Additionally, the effect of the Elasto-optic effect is also shown which results in a huge tunability of 650 nm and an increase in the modulation depth to 25.8 dB. The device has demonstrated its potential for use in filtering and switching for photonic integrated circuits. [ABSTRACT FROM AUTHOR]

Widely separated optical parametric oscillation (OPO) in an integrated Kerr microresonator offers a compact, highly coherent, and low‐power laser source, accessing previously inaccessible frequencies. Yet, extending the sideband of OPO from telecom to beyond 2 µm is still challenged by competing nonlinear effects and reduced Q factors at these extended wavelengths. In this work, efficient signal‐idler separations reaching 99 THz (1250–2130 nm) are demonstrated with a modest 8.1 mW threshold power, leveraging the heightened nonlinearity of GeSbS chalcogenide glass in the integrated microresonators. By pioneering energy dissipation control via pulley couplers, competing nonlinear phenomena are effectively suppressed, enabling the first demonstration of a widely separated OPO (wOPO) in the anomalous dispersion regime. Moreover, the wOPO features a robust existence region across a variety of device geometries, resilient to microresonator width alterations of up to 300 nm. These findings underscore the potential of integrated microresonators to adeptly bridge the telecom band to the MIR spectrum, achieving this transition with minimal power and controlled nonlinearities, a promising avenue for contemporary integrated photonics platforms utilizing heterogeneously integrated pump lasers. [ABSTRACT FROM AUTHOR]

Different methods are possible for estimating tidal deformations of Earth and telluric planets. On the one hand, the code ALMA 3 solves analytically the governing equations in considering symmetrical and incompressible bodies with homogeneous layers and different possible rheologies. Tidal deformations are considered with periodic excitation functions and the output of the model is frequency-dependent complex Love numbers. On the other hand, the 3-D finite element code CitcomSVE integrates numerically the governing equations with possibly lateral variations in viscoelastic structures on the regional and global scales. In this work, we present how tidal deformations have been implemented in CitcomSVE by the introduction of a periodic forcing potential. For validation and benchmarking, we realized comparisons between the ALMA 3 output for Moon tidal deformations and the numerical CitcomSVE in terms of frequency-dependent Love numbers k 2 and h 2 real and imaginary parts with 1-D viscoelastic structure. Considering two possible profiles for the Moon,we compared the frequency-dependent quality factor deduced from ALMA 3 with the one obtained with CitcomSVE. We found that with a sufficient numerical resolution for CitcomSVE (with an horizontal resolution of about 14 km and 10 - 5 for numerical accuracy), the results of the two methods for computing tidal deformations (i.e., k 2 and h 2 ) and quality factor Q are in good agreement for different periods including the monthly period (less than 0.025% for the real part of Love numbers and for the Q, about 1% for periods of excitation from 5 to 10 8 days). We also computed tidal dissipation energy from CitcomSVE and found it consistent with that expected from quality factor calculation. Our study demonstrates the potential for CitcomSVE to be applied for planetary tidal deformation calculations for a planet with a 3-D structure. [ABSTRACT FROM AUTHOR]

AbstractTelemedicine offers transformative solutions for healthcare delivery, particularly in bridging geographical barriers and enhancing patient care. Nevertheless, its adoption by physicians is intricate, driven by diverse factors that require systematic understanding. This systematic review aims to identify and classify the factors influencing physicians’ adoption of telemedicine. From a collection of 2098 articles sourced from Web of Science and Scopus databases, 59 studies met the predetermined criteria and were meticulously assessed. The salient factors from these chosen papers were segmented into distinct categories: psychological and behavioral factors, technological factors, social and cultural factors, security and privacy factors, conditional factors, quality factors, healthcare-related factors, and inhibiting factors. Building on this classification, we proposed a comprehensive framework for telemedicine adoption tailored to physicians. This framework endeavors to act as a scaffold for subsequent empirical investigations. The taxonomy of the factors also aided in offering numerous research agendas to pave the way for more exhaustive studies into telemedicine adoption among medical professionals. The insights procured serve not only to deepen theoretical comprehension but also to present pragmatic guidelines for practitioners, service providers, application developers, and decision-makers. [ABSTRACT FROM AUTHOR]

A structural analysis of the time series of pole coordinate changes (version C01 IERS) for the period of 1975.0–2011.0 has been performed based on the nonlinear least squares method. Average estimates of the parameters of the main components of the pole movement—namely, Chandler, annual, and semiannual wobbles—are obtained for this period. The obtained values of periods T and amplitudes A of the main components are as follows: T = 433.49 ± 0.22 days and A = 160 ± 3 mas for the Chandler oscillations; T = 365.19 ± 0.37 days and A = 93 ± 5 mas for the annual oscillations; and T = 183.03 ± 0.34 days and A = 4 ± 2 mas for the semiannual oscillations. Changes in the pole coordinates are examined in the time series when focusing on the manifestation of Chandler oscillations. The dynamics of oscillation parameters (including amplitude, period, phase, and Q factor) is studied. Changes in the Chandler oscillation parameters show their interdependence. The correlation coefficient between phase and period variations is +0.94, and a similar relationship is observed between phase and amplitude variations with a correlation coefficient of +0.88. It is shown that the phase change precedes the changes in the amplitude and in the period. This behavior of the parameters of the Chandler wobble suggests that changes in the period and in the amplitude should be considered a consequence of the phase changes. It is revealed that an increase in the amplitude of Chandler oscillations correlates with a decrease in the attenuation decrement with a correlation coefficient of –0.98. These findings align with the statistical patterns articulated by Melchior, which are indicative of (a) inconstancy of the period of Chandler oscillations over time and (b) proportional changes between the period and the amplitude of oscillations. Thus, preference should be given to the one-component complicated model of the Chandler pole movement with a variable period for the studied period of time. [ABSTRACT FROM AUTHOR]

The thermoelastic coupling between strain and temperature fields arising out from temperature gradient, while bending of an oscillating structure, leads to irreversible heat conduction, which causes energy dissipation in such vibrating systems. The estimation of thermoelastic damping (TED) in micro- and nano-mechanical resonators is a significant aspect of acquiring a high quality factor (Q-factor). Yang et al. [Couple stress based strain gradient theory for elasticity. Int J Solids Struct. 2002;39(10):2731–2743.] developed the modified couple stress theory (MCST) that involves only one material length scale parameter. The present work attempts to investigate TED in micro/nano-beam resonators utilizing MCST and the recently proposed Moore–Gibson–Thompson (MGT) generalized thermoelasticity theory. Adopting the frequency approach method, we derive the size-dependent expression of the inverse quality factor for evaluating TED in rectangular micro/nano-beam resonators. Furthermore, the impact of the material length scale parameter on TED associated with MCST for silicon micro-beam resonator is investigated in detail by comparing the present results with those predicted by classical continuum theory (CCT). The obtained results are also compared with the existing results for the Lord–Shulman (LS) and Green–Naghdi (GN-III) thermoelasticity theories. Moreover, the effects of other important parameters like beam thickness, beam length, aspect ratio, phase-lag on TED in the present context are highlighted. [ABSTRACT FROM AUTHOR]

This paper presents a cooperative game theory approach to improve the video steganography framework. Wherein, the video steganography framework comprises the following steps: (1) Cover video devising, (2) Secret image pre-processing, and (3) Embedding process. In the first step, the cover video is segmented using scene change detection method. Once the scenes are segmented the motion vectors are identified by Block Matching Motion Estimation Algorithm (BMMEA). Based on these motion vectors, the Region of Interest (ROI) is selected. The selected ROI is grouped using their momentum. In order to add an additional layer of security, the secret image is scrambled using pixel-wise Arnold Transform in the next step. Finally, based on the ROI groups, the scrambled secret data is embedded into the ROI's locations. An ideal and perfect video steganography system should be able to maintain the quality of the video after embedding the secret data. The quality factors of the video steganography approach include perceptible invisibility, payload capacity, and robustness. However, these quality factors are conflicted with each other. In order to address this issue, having these three quality factors as players a cooperative 3-players game theory approach is proposed. This technique provides an optimal solution for the video steganography framework using strategy adaption. The optimal solution is acquired by applying the Iterative Elimination of Strictly Dominant Strategies (IESDS) method. The achieved optimal solution comes up with the best trade-off between the quality factors. Experimental results have deduced the best optimal solution from the proposed three-player game theoretic approach that helps the video steganography approach to resolve the quality and security issues. It is also observed that the optimized proposed method outperforms the contemporary methods by attaining significant outcomes. [ABSTRACT FROM AUTHOR]

In the rapidly evolving landscape of cyber threats, effective defense strategies are crucial for safeguarding sensitive information and critical systems. Deep learning methods, notably the Transformer architecture, have shown immense potential in addressing cybersecurity challenges. However, customizing, and adapting Transformer architectures for cybersecurity applications presents a challenge, demanding the utilization of effective strategies to achieve optimal performance. This study presents a comprehensive analysis of design tactics employed in tailoring Transformer architectures specifically for cybersecurity problems. Design tactics, defined as strategic solutions to architectural challenges based on well-justified design decisions, are explored in-depth within the context of cybersecurity. By examining the modifications and adaptations made to the original Transformer architecture, this study unveils the design decisions and strategies crucial for successful implementation in diverse cybersecurity domains. The findings emphasize the significance of aligning design tactics with the unique business requirements and quality factors of each specific application domain. This study contributes valuable insights into the utilization of design tactics for customizing Transformer architectures in cybersecurity, paving the way for enhanced defense strategies against the dynamic and evolving nature of cyber threats. [ABSTRACT FROM AUTHOR]

Based on the theory of nonlinear piezoelectricity, an approximate solution for electrically forced nonlinear thickness-shear vibrations of piezoelectric plates is introduced. The model considers an infinite piezoelectric plate subjected to an alternative voltage, incorporating 3rd-order and 4th-order elastic constants and viscous damping under finite deformation. The system's differential equations for steady-state forced vibrations are derived from the nonlinear pure thickness-shear vibration problem, and transformed so that the new electrical boundary conditions are free. After the application of Galerkin's method, the transformed differential equations lead to a cubic equation, capturing the nonlinear current-frequency curves of AT-cut quartz plates without the need of the quality factor Q, due to the introduced viscous damping. When the damping effect is ignored, the frequency response curves of the AT-cut quartz plate under a specific voltage are confirmed with the existing literature. The study emphasizes the presence of the critical voltage and the importance of the fourth-order elastic constant (c 6666) in the stability, revealing lower c 6666 values correspond to improved stability. Additionally, a proposed algorithm efficiently determines critical voltages for resonator stability. • A cubic equation predicts the nonlinear behavior of piezoelectric resonators. • The decrease of c 6666 improves the stability of piezoelectric resonators. • The amplitude-frequency curve has a hysteresis region when voltage is that high. • An efficient algorithm for the critical voltage is suggested. [ABSTRACT FROM AUTHOR]

A series of microwave dielectric ceramics, (1-x)Na 0.5 Y 0.5 MoO 4 -xNa 0.5 Bi 0.5 MoO 4 , with low sintering temperatures and excellent microwave dielectric properties, were prepared by solid-state reaction. The ceramics were sintered well at 820 oC, and the structure, microwave dielectric properties, and chemical compatibility were investigated. When x=0.1, the microwave dielectric constant (ε r), the quality factor (Q × f value), and the temperature coefficient of resonant frequency (TCF value) of the 0.9NYM-0.1NBM ceramic were 10.9(±0.2), 54,060(±1,000) GHz, and -48.6(±1) ppm/°C, respectively. When x=0.7, the ε r of the 0.3NYM-0.7NBM ceramic was 23.6(±0.5), the Q × f value was 19,020(±400) GHz, the TCF value was -3.1(±0.1) ppm/°C and the room temperature thermal conductivity was 1.21(±0.01) W/(m.K). After co-firing with 20 w.t. % silver powder at 820 °C, it was found that (1-x)NYM-xNBM ceramics were chemically compatible with Ag electrodes, indicating their potential as alternative materials for low-temperature co-fired ceramics (LTCC). [ABSTRACT FROM AUTHOR]

Estimating wave damping in carbonate rocks is complex due to their heterogeneous structure. For this reason, further research in this area is still necessary. Since the identification and evaluation of reservoir quality play an essential role in the optimal use of hydrocarbon resources, efforts are made to provide new solutions to achieve this goal by managing knowledge and accessing information from new tools such as the Vertical Seismic Profile (VSP). Seismic waves are deformed in frequency content and amplitude as they pass through the earth's layers. Part of the reduction in wavelength is related to the nature of the wave propagation and part to the geological properties, including porosity and fracture. Anisotropy and velocity model analysis, rather than the direct connection between reservoir parameters and seismic absorption coefficient, have received the majority of attention in earlier studies on the impact of reservoir parameters and fractures on changes in the quality factor. In this study, the correlation of the quality factor with parameters such as velocity deviation, fracture density, and permeability has been investigated, and an attempt has been made to define the quality factor as a tool to assess the quality of the reservoir. The statistical study using the multiple linear regression method found that fracture density is the most important parameter that follows the trend of the quality factor value. In the analysis, the quality factor showed a relatively good correlation with the permeability of the core data, so in the periods with maximum permeability, the quality factor had the lowest values. According to K-Means Clustering Analysis, 18% of the studied reservoir interval was evaluated as good quality, 33% as medium, 36% as poor, and 12% as hydrocarbon-free. This work provides insight into accessing reservoir quality using quality factor and velocity deviation logs and would be valuable for the development of reservoir quality prediction methods. Based on the study's results, it is recommended to apply this technique for modeling reservoir heterogeneity and assessing 2D and 3D seismic data to predict the reservoir quality of gas fields prior to drilling operations and reduce exploration risks. [ABSTRACT FROM AUTHOR]

Inverse Q filtering is a common tool in seismic processing that can be used to improve the resolution of post-stack seismic data. However, it is difficult to obtain the Q value conveniently and precisely, which limits the precision and industrial application range of inverse Q filtering. In this study, a set of technology schemes based on a BP neural network is proposed to quickly acquire the Q field so that inverse Q filtering has the ability to adapt to inhomogeneous Q values. Based on the powerful nonlinear solving ability of the BP neural network, the functional mapping relationship between the Q value and spectral information of seismic data is established, which improves the anti-noise ability of Q value prediction. The application effect of the model and actual data verifies the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

In order to explore the interactive effects of environmental factors on the chlorophyll-a (Chl-a) concentration variation in Honghu Lake, this study was based on the monitoring data of Chl-a mass concentration and water quality factors (water temperature, pH, dissolved oxygen, permanganate index, total nitrogen, total phosphorus) and meteorological factors (evaporation, precipitation, sunshine hours, average wind speed) at three research sites (Dakou, Chatan Island, Lantian) in Honghu Lake from January 2010 to December 2019. Time series analysis, piecewise structural equation model (PiecewiseSEM), and generalized additive model (GAM) were used to quantitatively study the spatial and temporal changes of different environmental factors and their interaction with chlorophyll-a concentration in Honghu Lake. The results showed that the effects of TN and DO on Chl-a at Dakou and Chatan Island were more significant than other environmental meteorological factors, while the effects of DO and CODMn on Chl-a at Lantian were more obvious. At the same time, it was found that Chl-a had a non-linear relationship with TN and DO at Dakou and Chatan Island, a non-linear relationship with DO at Lantian, and a linear relationship with CODMn. The interaction effect of dominant environmental meteorological factors on Chl-a was significantly higher than that of a single factor, and the explanation rates were 80.6%, 72.8%, and 64.6%, respectively. In conclusion, based on the Piecewise SEM and GAM model, it not only can reveal the influence of the interaction of influencing factors on the change of Chl-a concentration, but also has important significance for the early warning and control of lake eutrophication. [ABSTRACT FROM AUTHOR]

Metal‐dielectric photonic crystals (MDPCs) are a class of photonic structure formed through the coupling of metallic microcavities. Interaction of the cavities results in hybridization of the underlying microcavity states to form photonic bands defined by the crystal periodicity, metal‐to‐dielectric ratio, and number of unit cells. In this study, we provide analytical solutions for the resonant states of discrete 1D MDPCs with an arbitrary number of cavities using quasinormal mode (QNM) theory. Our results show that the QNM solutions closely match the predictions of coupled mode theory (CMT) in the tight‐binding regime and diverge as the metal thickness vanishes. We apply the QNM results to the CMT model to find analytical expressions for the inter‐cavity coupling coefficients. Additionally, we analyze the quality factor, transmission, and absorption of both ideal and lossy MDPCs, revealing important trends in bulk optical properties. [ABSTRACT FROM AUTHOR]

Radio over fiber (ROF) is a very attractive technology for the increasing demand for flexibility and transmission capacity and due to its high bandwidth and low attenuation, it offers an economic advantage. The wavelength division multiplexing (WDM) is used to multiplex the different wavelengths signals within a single optical fiber. In this paper, WDM-ROF system is analysed with different filters using an optisystem. Results were compared using max Q factor, min BER, and eye height parameters. [ABSTRACT FROM AUTHOR]

We report the designing of a free-space-optics (FSO) transmission system capable of transmitting high rate information by utilising novel mode division multiplexing (MDM) transmission technique. In the work reported, 2-channels transmitting 10 Gbps data, using either non-return-to-zero (NRZ) encoding scheme or return-to-zero (RZ) encoding scheme are modulated by using different Hermite–Gaussian (HG) modal beams of the single laser beam to realize of 20 Gbps transmission system. The system proposed is simulative analysed under the effect of different weather states. Also, we have compared the bit error rate (BER) and Quality factor (Q Factor) performance for RZ and NRZ encoding schemes in the system for varying weather states. The results reported show that NRZ encoding exhibits a superior performance. Also, we have analysed the system performance by taking into consideration atmospheric scintillation effect and the reported results show notable signal degradation in the presence of scintillation. [ABSTRACT FROM AUTHOR]

In this work, non-stoichiometric Li2(1+x)Mg3Ti4O12 (LxMTO, x = 0.00–0.05) ceramics with excess lithium were prepared through a simple reaction sintering route to suppress lithium volatilization. According to the characterization of the phase composition and microscopic morphology of the pellets, single-phase LxMTO ceramics with a good microstructure were obtained. Excess lithium effectively inhibited the volatilization and optimized the morphology of the ceramics. A trend in relative density with an initial increase followed by a steep decrease was a predominant observation with the change in dielectric properties. The permittivity of the samples was dominated by the relative density and distortion of the [TiO6] octahedron structure caused by Li+. The dielectric loss primarily originated from the refraction loss and scattering generated by pores, and the grain boundaries also contributed to the loss in the quality factor. Ultimately, at 1220°C, the Li2.08Mg3Ti4O12 ceramics exhibited excellent microwave dielectric properties: εr = 17.83, Q×f = 69,823 GHz and τf = −18.19 ppm/°C. [ABSTRACT FROM AUTHOR]

A high quality (Q) factor is essential for enhancing the performance of resonant nanoelectromechanical systems (NEMS). NEMS resonators based on two-dimensional (2D) materials such as molybdenum disulfide (MoS2) have high frequency tunability, large dynamic range, and high sensitivity, yet room-temperature Q factors are typically less than 1000. Here, we systematically investigate the effects of device size and surface nonidealities on Q factor by measuring 52 dry-transferred fully clamped circular MoS2 NEMS resonators with diameters ranging from 1 μm to 8 μm, and optimize the Q factor by combining these effects with the strain-modulated dissipation model. We find that Q factor first increases and then decreases with diameter, with an optimized room-temperature Q factor up to 3315 ± 115 for a 2-μm-diameter device. Through extensive characterization and analysis using Raman spectroscopy, atomic force microscopy, and scanning electron microscopy, we demonstrate that surface nonidealities such as wrinkles, residues, and bubbles are especially significant for decreasing Q factor, especially for larger suspended membranes, while resonators with flat and smooth surfaces typically have larger Q factors. To further optimize Q factors, we measure and model Q factor dependence on the gate voltage, showing that smaller DC and radio-frequency (RF) driving voltages always lead to a higher Q factor, consistent with the strain-modulated dissipation model. This optimization of the Q factor delineates a straightforward and promising pathway for designing high-Q 2D NEMS resonators for ultrasensitive transducers, efficient RF communications, and low-power memory and computing. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC)'s nonlinear optical properties and applications to quantum information have recently brought attention to its potential as an integrated photonics platform. However, despite its many excellent material properties, such as large thermal conductivity, wide transparency window, and strong optical nonlinearities, it is generally a difficult material for microfabrication. Here, it is shown that directly bonded silicon‐on‐silicon carbide can be a high‐performing hybrid photonics platform that does not require the need to form SiC membranes or directly pattern in SiC. The optimized bonding method yields defect‐free, uniform films with minimal oxide at the silicon–silicon–carbide interface. Ring resonators are patterned into the silicon layer with standard, complimentary metal–oxide–semiconductor (CMOS) compatible (Si) fabrication and measure room‐temperature, near‐infrared quality factors exceeding 105. The corresponding propagation loss is 5.7 dB cm−1. The process offers a wafer‐scalable pathway to the integration of SiC photonics into CMOS devices. [ABSTRACT FROM AUTHOR]

The development of manufacturable and scalable integrated nonlinear photonic materials is driving key technologies in diverse areas, such as high-speed communications, signal processing, sensing, and quantum information. Here, we demonstrate a nonlinear platform—InGaP-on-insulator—optimized for visible-to-telecommunication wavelength χ (2) nonlinear optical processes. In this work, we detail our 100 mm wafer-scale InGaP-on-insulator fabrication process realized via wafer bonding, optical lithography, and dry-etching techniques. The resulting wafers yield 1000 s of components in each fabrication cycle, with initial designs that include chip-to-fiber couplers, 12.5-cm-long nested spiral waveguides, and arrays of microring resonators with free-spectral ranges spanning 400–900 GHz. We demonstrate intrinsic resonator quality factors as high as 324 000 (440 000) for single-resonance (split-resonance) modes near 1550 nm corresponding to 1.56 dB/cm (1.22 dB/cm) propagation loss. We analyze the loss vs waveguide width and resonator radius to establish the operating regime for optimal 775–1550 nm phase matching. By combining the high χ (2) and χ (3) optical nonlinearity of InGaP with wafer-scale fabrication and low propagation loss, these results open promising possibilities for entangled-photon, multi-photon, and squeezed light generation. [ABSTRACT FROM AUTHOR]

Evidence of strongly confined coherent acoustic phonons inside high quality factor phononic cavities that exhibit tailored phonon potentials is provided. Using GaAs/AlAs quasiperiodic superlattices, functional phonon potentials are realized by adiabatically changing the layer thicknesses along the growth direction. Room temperature ultrafast vibrational spectroscopy reveals discrete phonon modes with frequencies in the range of ≈96–101 GHz. Additionally, it is confirmed that phononic cavities impact the energy loss rate of the photoexcited carriers, as evidenced by time‐resolved photoluminescence measurements. These results highlight the potential of concurrently engineering optoelectronic and phononic properties for a range of novel applications. [ABSTRACT FROM AUTHOR]

As they have gained maturity, colloidal nanocrystals (NCs) have also expand the spectral range over of which they could be used for photonic and optoelectronic applications. In particular, the infrared use of NCs has become of utmost interest to develop cost‐effective alternatives to current technologies. It is then critical not to let the material dictate the light–matter interaction, which is why the coupling of NCs to photonic cavities has been proposed. For infrared NCs, this approach has first been devoted to the control of absorption with in mind the increase of the signal magnitude for detectors. A Lot of efforts have been focused on the use of metallic metasurfaces. However, these generate significant optical losses and yield low quality factor. Here, this study rather focus on the coupling of infrared NCs to a dielectric mirror cavity. HgTe/CdS core‐shell NCs are used and integrated into a cavity made of aperiodic dielectric mirrors. The effect of the substrate is systematically study on spectral linewidth, carrier dynamic, and emission directivity. The cavity is shown to narrow the PL by a factor 10, while focusing the emission over a 12° angle. Monitoring the power dependence of the emission, this study shows that the cavity leads to 250 K increase in the effective electronic temperature. [ABSTRACT FROM AUTHOR]

As a part of the service industry, product design practitioners should possess an understanding of the multifaceted factors and solutions that contribute to delivering exceptional service quality. However, related research on the service quality factors and solutions for China's ceramic product design industry is still an important research gap. In view of this, an integrated approach based on multi-criteria decision making (MCDM), combining the fuzzy analytic hierarchy process (FAHP) and the measurement of alternatives and ranking according to compromise solution (MARCOS), was proposed in this research to analyse and evaluate the service quality factors and solutions for China's ceramic product design industry. Initially, the FAHP method determined the significance of the service quality dimensions and indicators. Subsequently, the MARCOS method ranked the alternatives based on their performance against these criteria. This research focuses on the growing subject of service quality in China's ceramic product design industry. The proposed model identifies essential service quality factors and solutions for China's ceramic product design industry. The findings of this study may assist ceramic product design practitioners in China in making strategic decisions to provide excellent service quality. [ABSTRACT FROM AUTHOR]

Niobium films are a key component in modern two-dimensional superconducting qubits, yet their contribution to the total qubit decay rate is not fully understood. The presence of different layers of materials and interfaces makes it difficult to identify the dominant loss channels in present two-dimensional qubit designs. In this paper, we present the study that directly correlates measurements of RF losses in such films to material parameters by investigating a high-power impulse magnetron sputtered (HiPIMS) film atop a three-dimensional niobium superconducting radio frequency (SRF) resonator. By using a 3D SRF structure, we are able to isolate the niobium film loss from other contributions. Our findings indicate that microwave dissipation in the HiPIMS-prepared niobium films, within the quantum regime, resembles that of record-high intrinsic quality factor of bulk niobium SRF cavities, with lifetimes extending into seconds. Microstructure and impurity level of the niobium film do not significantly affect the losses. These results set the scale of microwave losses in niobium films and show that niobium losses do not dominate the observed coherence times in present two-dimensional superconducting qubit designs, instead highlighting the dominant role of the dielectric oxide in limiting the performance. We can also set a bound for when niobium film losses will become a limitation for qubit lifetimes. [ABSTRACT FROM AUTHOR]

Real‐world resonances face surface‐scaling radiation leakage, hindering light confinement in optically large systems. Conventional bound states in continuum (BICs) challenge this by enabling states with theoretically infinite lifetimes in 2D periodic structures. However, when fabricated, the truncation of these systems to finite sizes inevitably re‐introduces leakage, uncontrollably downgrading their quality factors. Here, a novel form of finite‐size 3D quasi‐BICs (QBICs) is demonstrated that leverage a skyrmion field topology of Bloch modes in 3D cubic photonic crystals. The associated finite systems exhibit highly suppressed radiation in all three spatial directions, with a remarkable exponential volume‐scaling of quality factors. With an unprecedentedly large 3D prototype of 24 cm3 and great scalability, the existence of skyrmion QBICs is experimentally proven through unique far‐field polarization wrapping and spectral singularity. These demonstrations enable to have omnidirectional topological radiation suppression, 3D vortex generation, and access to arbitrarily large volume and volumetric interfaces. 3D QBIC may empower extreme 3D light‐trapping, enhanced volumetric sensing, and topological skyrmion emitters. [ABSTRACT FROM AUTHOR]

The physical and chemical state of ceramics are very important for their microwave dielectric properties, especially at high frequencies above GHz. Therefore, the microstructure and microwave dielectric properties of (1- x)Mg(Zr 0.05 Ti 0.95)O 3 – x SrTiO 3 ((1- x)MZT– x ST) ceramics were investigated by controlling external variables. The compounds were synthesized through a solid-state reaction mechanism and sintered at relatively low temperatures. A cavity resonator method was employed to analyze the microwave dielectric properties. Optimal sintering conditions significantly enhanced the microwave dielectric performance of MZT ST ceramics. The addition of ZnO substantially reduced the sintering temperature and equilibrium sintering time, enabling the activation of optimal conditions and the achievement of temperature-stable microwave dielectrics like NP0: ε r ∼20.16 at 10 GHz, Q f of ∼81839 GHz at 7.93 GHz, and τ f close to zero (∼0.12 ppm/°C). This enhanced performance was attributed to the optimization of internal variables, including enhanced relative density, homogeneous grain size, optimal phase fraction, and chemical ordering. [ABSTRACT FROM AUTHOR]

Piezoelectric ultrasonic energy harvesters (PUEHs) have recently attracted increasing attention. For minimizing the energy losses during energy transfer, it is crucial for core piezoelectric materials to maintain high piezoelectric coefficient (d 33), mechanical quality factor (Q m), and piezoelectric voltage coefficient (g 33). Herein, a simple way of hardening strategy improves the piezoelectric properties of KNN-based ceramics, combined with optimizing grain growth. The enhanced d 33 (∼340 pC/N), high Q m (∼211) and T C (∼305 °C) are obtained simultaneously in this system, accompanied by superior d 33 × g 33 =8770×10−15 m2/N. Through variable temperature resonance test, the polarization rotation diversity caused by phase structure difference is found to closely related to the temperature stability of Q m value. A prototype of PUEH device was further designed and fabricated, with adjustable ultrasound-induced output voltage up to 8.2 V. Our work exhibits an effective way to improve performance of PUEHs by optimizing piezoelectric materials, which is helpful for further developing PUEHs. [ABSTRACT FROM AUTHOR]

Forsterite was synthesized with MgCO 3 and SiO 2 powders using a solid-state method at 1200–1300°C. The ceramic specimen with the highest forsterite phase content was sintered with the ZrO 2 sintering aid at mass fractions of 0.5, 1.0, and 1.5 wt% at 1400°C for 4 h. The dielectric constant and loss tangent were also measured via the waveguide method at 8–12 GHz. The formation of enstatite and cristobalite was minimized through precise synthesis temperature control. Phase measurement by the Rietveld method showed that specimen F28 contained more than 99.8% forsterite. It was found that ZrO 2 reduced the pore volume percent and increased the density even at low mass fractions. A liquid phase on the grain boundaries was demonstrated. The solid ceramic specimen F28-15Z showed a dielectric constant of 6.5 and high quality factor of 189000. [ABSTRACT FROM AUTHOR]

This study investigates a hybrid microelectromechanical system (MEMS) acoustic resonator through a hybrid approach to combine capacitive and piezoelectric transduction mechanisms, thus harnessing the advantages of both transducer technologies within a single device. By seamlessly integrating both piezoelectric and capacitive transducers, the newly designed hybrid resonators mitigate the limitations of capacitive and piezoelectric resonators. The unique hybrid configuration holds promise to significantly enhance overall device performance, particularly in terms of quality factor (Q-factor), insertion loss, and motional impedance. Moreover, the dual-transduction approach improves the signal-to-noise ratio and reduces feedthrough noise levels at higher frequencies. In this paper, the detailed design, complex fabrication processes, and thorough experimental validation are presented, demonstrating substantial performance enhancement potentials. A hybrid disk resonator with a single side-supporting anchor achieved an outstanding loaded Q-factor higher than 28,000 when operating under a capacitive drive and piezoelectric sense configuration. This is comparably higher than the measured Q-factor of 7600 for another disk resonator with two side-supporting anchors. The hybrid resonator exhibits a high Q-factor at its resonance frequency at 20 MHz, representing 2-fold improvement over the highest reported Q-factor for similar MEMS resonators in the literature. Also, the dual-transduction approach resulted in a more than 30 dB improvement in feedthrough suppression for devices with a 500 nm-thick ZnO layer, while hybrid resonators with a thicker piezoelectric layer of 1300 nm realized an even greater feedthrough suppression of more than 50 dB. The hybrid resonator integration strategy discussed offers an innovative solution for current and future advanced RF front-end applications, providing a versatile platform for future innovations in on-chip resonator technology. This work has the potential to lead to advancements in MEMS resonator technology, facilitating some significant improvements in multi-frequency and frequency agile RF applications through the original designs equipped with integrated capacitive and piezoelectric transduction mechanisms. The hybrid design also results in remarkable performance metrics, making it an ideal candidate for integrating next-generation wireless communication devices where size, cost, and energy efficiency are critical. [ABSTRACT FROM AUTHOR]

The stepped‐impedance combline band pass filter (BPF) with novel input and output networks based on a new proposed J‐inverter, which increases the center frequency tuning range with constant bandwidth (BW), is discussed. The even and odd mode analysis shows that the stepped resonators provide the necessary conditions for the appropriate coupling coefficient to keep the BW constant. In order to create an appropriate quality factor, the new proposed J‐inverter is used. In the frequency response of the stopband region, three transition zeros (TZs) are generated, which two of TZs are controllable. The proposed tunable BPF has been fabricated on RO4003 substrate with a dielectric constant of 3.38 and 0.813 mm thickness. The size of the filter is compact and is only 0.31λg×0.1λg$$ 0.31{\lambda}_{\mathrm{g}}\times 0.1{\lambda}_{\mathrm{g}} $$, where λg$$ {\lambda}_{\mathrm{g}} $$ is the guided wavelength at the lower center frequency. The center frequency is equal to 1.723 GHz and a frequency tuning range from 1.2 GHz to 2.246 GHz with 100 MHz constant 3 dB absolute BW, the insertion loss of 1.4–3.17 dB and return loss of 17.8–25.9 dB is achieved. [ABSTRACT FROM AUTHOR]