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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]

Acceptor doping is a common method for hardening modified piezoelectric ceramics. The mechanism through which the hardening effect can be improved has been widely studied and verified. However, the effect of defects caused by different valence states of the B‐site ions on the properties of multicomponent piezoelectric ceramics remains to be discussed. Therefore, in this work, a novel Pb(Ni1/3Nb2/3)O3–Pb(In1/2Nb1/2)O3–Pb(Mn1/3Nb1/2)–PbTiO3 quaternary hard ceramic with excellent performance is prepared and studied. The interaction between grain‐boundary defects and defect dipoles is proposed to be the mechanism behind the observed excellent performance. It is found that different types of defects improve the hardening effect in various ways. These results can provide a theoretical basis for the preparation of multicomponent piezoelectric ceramics with better properties. [ABSTRACT FROM AUTHOR]

Planar chiral metasurfaces have demonstrated their proficiency in manipulating chiral light‐matter interactions for diverse applications. Nevertheless, it proves arduous to simultaneously attain elevated quality factors and potent chirality response. In this work, a planar chiral metasurface is proposed, that supports Brillouin zone folding‐induced bound states in the continuum (BZF‐BICs) featuring a high‐Q factor resonance and near‐perfect circular dichroism response. By introducing periodic perturbation and breaking symmetry, the BZF‐BICs exhibit a folded band structure and decreased radiative channels, leading to a superior quality factor relative to unfolded quasi‐BICs. Exploiting the topological nature of BZF‐BICs, the polarization singularity is eradicated, resulting in the appearance of two elliptical eigenstate polarizations. Consequently, an almost perfect circular dichroism response is demonstrated due to the selective coupling between the eigenstate and the incident light. Furthermore, it is revealed that the symmetry of the distribution of eigenstates in the BZF‐BICs lattice is determined by the perturbed cell, and the more intricate orthogonal polarization states can be distinguished through the Brillouin zone design, enabling the splitting of complex polarization state beams. This study presents an innovative method for creating easily fabricated chiral metasurfaces and holds promise for applications in biochemical sensing, emission, lasing, quantum optics, and nonlinear optics. [ABSTRACT FROM AUTHOR]

Hyperuniform disordered solids (HUDS) waveguides, a type of emerging artificial photonic bandgap (PBG) devices, are demonstrated to possess large, complete, and isotropic PBGs, being promising for developing applications in optoelectronics, nonlinear optics, and sensing. However, optical losses of HUDS waveguides are usually limited by giant light scattering from the irregular distribution of HUDS cells. Herein, HUDS waveguide devices are demonstrated with low optical losses and large PBGs by exploring a morphology‐engineering and wall‐network‐regulation method of developing HUDS structures. The results show that the proposed device can achieve a 3.0 dB transmittance improvement for a 36‐µm‐long silicon HUDS waveguide. Based on the proposed HUDS structure, a waveguide‐coupled HUDS‐cladding nanocavity is also demonstrated with a quality factor of ≈70 at 2.250 µm wavelengths and a theoretical refractive index sensitivity of 446 nm RIU−1. The study opens an avenue to develop intriguing HUDS waveguide devices for on‐chip applications. [ABSTRACT FROM AUTHOR]

Quantum information technology offers the potential to realize unprecedented computational resources via secure channels distributing entanglement between quantum computers. Diamond, as a host to optically-accessible spin qubits, is a leading platform to realize quantum memory nodes needed to extend such quantum links. Photonic crystal (PhC) cavities enhance light-matter interaction and are essential for an efficient interface between spins and photons that are used to store and communicate quantum information respectively. Here, we demonstrate one- and two-dimensional PhC cavities fabricated in thin-film diamonds, featuring quality factors (Q) of 1.8 × 105 and 1.6 × 105, respectively, the highest Qs for visible PhC cavities realized in any material. Importantly, our fabrication process is simple and high-yield, based on conventional planar fabrication techniques, in contrast to the previous with complex undercut processes. We also demonstrate fiber-coupled 1D PhC cavities with high photon extraction efficiency, and optical coupling between a single SiV center and such a cavity at 4 K achieving a Purcell factor of 18. The demonstrated photonic platform may fundamentally improve the performance and scalability of quantum nodes and expedite the development of related technologies. Improving the performance and scalability of quantum nodes is of paramount importance to expedite the development of quantum technologies. Here the authors demonstrate fiber-coupled 1D PhC cavities with high photon extraction efficiency, and optical coupling between a single SiV center and such a cavity. [ABSTRACT FROM AUTHOR]

AbstractNon-medical masks such as disposable non-medical, commercially produced cloth, and homemade masks are not regulated like surgical masks. Their performance, in terms of filtration efficiency and breathability, is variable and unreliable. This research provides a quantitative evaluation of various non-medical masks, assesses their fabrics’ potential for the reduction of transmission of bioaerosols such as the SARS-CoV-2 virus, and compares them to surgical masks and N95 filtering facepiece respirators. Using a testing line with a NaCl challenge aerosol, four types of commercial reusable cloth masks, two types of disposable non-medical masks, three types of surgical or N95 masks, and seven types of commonly available materials were tested individually and in combinations. The testing line and procedure were adapted from the ASTM F2299-03: Standard Test Method for Determining the Initial Efficiency of Materials Used in Medical Face Masks to Penetration by Particulates Using Latex Spheres testing method used for testing surgical masks. Filtration efficiencies at 0.15 µm particle diameter at a face velocity of 25 cm/sec for commercial cloth masks, disposable non-medical masks, surgical masks, commercial mask combinations, and homemade combinations ranged from 16–29%, 39–76%, 91–97%, 51–95%, and 45–94%, respectively. The pressure drop results for the different masks and material combinations were all under 3 mm H2O/cm2 except for one material configuration. This study builds on other research that looks at individual materials and masks by testing combinations alongside the individual masks and materials. With proper layering, household materials can achieve the filtration efficiency and low pressure drop requirements of surgical masks. The filtration capabilities of disposable and cloth mask fabrics vary considerably meaning that they are not a reliable or consistent facemask option, regardless of fit. [ABSTRACT FROM AUTHOR]

It has recently been shown that a bolus of hyperpolarized nuclear spins can yield stimulated emission signals similar in nature to maser signals, potentially enabling new ways of sensing hyperpolarized contrast media, including most notably [1‐13C]pyruvate that is under evaluation in over 50 clinical trials for metabolic imaging of cancer. The stimulated NMR signal emissions lasting for minutes do not require radio‐frequency excitation, offering unprecedented advantages compared to conventional MR sensing. However, creating nuclear spin maser emission is challenging in practice due to stringent fundamental requirements, making practical in vivo applications hardly possible using conventional passive MR detectors. Here, we demonstrate the utility of a wireless NMR maser detector, the quality factor of which was enhanced 22‐fold (to 1,670) via parametric pumping. This active‐feedback technique breaks the intrinsic fundamental limit of NMR detector circuit quality factor. We show the use of parametric pumping to reduce the threshold requirement for inducing nuclear spin masing at 300 MHz resonance frequency in a preclinical MRI scanner. Indeed, stimulated emission from hyperpolarized protons was obtained under highly unfavorable conditions of low magnetic field homogeneity (T2* of 3 ms). Greater gains of the quality factor of the MR detector (up to 1 million) were also demonstrated. [ABSTRACT FROM AUTHOR]

Microwave-driven trapped ion logic gates offer a promising avenue for advancing beyond laser-based logic operations. In future microwave-based operations, however, the joule heat produced by large microwave currents flowing through narrow microwave electrodes would potentially hinder improvements in gate speed and fidelity. Moreover, scalability, particularly in cryogenic trapped ion systems, is impeded by the excessive joule heat. To address these challenges, we present a novel approach: superconducting surface trap chips that integrate high-Q microwave resonators with large current capacities. Utilizing sub-ampere microwave currents in superconducting Nb resonators, we generate substantial magnetic field gradients with significantly reduced losses compared to conventional metal chips. By harnessing the high Q factors of superconducting resonators, we propose a power-efficient two-qubit gate scheme capable of achieving a sub-milliwatt external microwave input power at a gate Rabi frequency of 1 kHz. [ABSTRACT FROM AUTHOR]

The demand for high-performance electromechanical resonators is ever-growing across diverse applications, ranging from sensing and time-keeping to advanced communication devices. Among the electromechanical materials being explored, thin-film lithium niobate stands out due to its strong piezoelectric properties and low acoustic loss. However, in nearly all existing lithium niobate electromechanical devices, the configuration is such that the electrodes are in direct contact with the mechanical resonator. This configuration introduces an undesirable mass-loading effect, producing spurious modes and additional damping. Here, we present an electromechanical platform that mitigates this challenge by leveraging a flip-chip bonding technique to separate the electrodes from the mechanical resonator. By offloading the electrodes from the resonator, our approach yields a substantial increase in the quality factor of these resonators, paving the way for enhanced performance and reliability for their device applications. [ABSTRACT FROM AUTHOR]

The confinement of waves in open systems represents a fundamental phenomenon extensively explored across various branches of wave physics. Recently, significant attention is directed toward bound states in the continuum (BIC), a class of modes that are trapped but do not decay in an otherwise unbounded continuum. Here, the theoretical investigation and experimental demonstration of the existence of quasi‐bound states in the continuum (QBIC) for ultrasonic waves are achieved by leveraging an elastic Fabry–Pérot metasurface resonator. Several intriguing properties of the ultrasound quasi‐bound states in the continuum that are robust to parameter scanning are unveiled, and experimental evidence of a remarkable Q‐factor of 350 at ≈1 MHz frequency, far exceeding the state‐of‐the‐art using a fully acoustic underwater system is presented. The findings contribute novel insights into the understanding of BIC for acoustic waves, offering a new paradigm for the design of efficient, ultra‐high Q‐factor ultrasound devices. [ABSTRACT FROM AUTHOR]

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With the rapid fusion of temperature sensing technology and microwave technology, microwave temperature sensors have become the protagonist of competing research. We propose a planar resonator temperature sensor that combines substrate material modifications with sensor structure design. To realize this concept, high-performance TiO2-xwt. % ZnO (0 ≤ x ≤ 3) microwave dielectric ceramics are prepared. The various factors influencing dielectric properties, including crystal structure, phase composition, Raman vibration, microstructure, element valence, and oxygen vacancy, are completely investigated. The TiO2-0.7 wt. % ZnO ceramic exhibiting exceptional properties (εr = 106.6, Qf = 46 000 GHz, τf = 426.0 ppm/°C) is selected for substrate fabrication. The frequency and temperature dependence of εr and tan δ are analyzed at 2–4.5 GHz from −50 to 100 °C, revealing a good linearity between εr and temperature. A CSRR temperature sensor employing this substrate material is designed, simulated, fabricated, and validated from −50 to 90 °C. This sensor generates two resonance frequencies (around 0.5 and 1.4 GHz) in the UHF band, demonstrating sensitivities of 2.2 MHz/10 °C and 6.3 MHz/10 °C at the first and second resonance frequencies, along with an outstanding normalized sensitivity of approximately 0.045. Through a comprehensive analysis of the physical mechanisms affecting the sensor's sensitivity and quality factor, the design of the sensor is strengthened from the perspective of optimizing the performance of microwave dielectric ceramics. The regulation mechanism of dielectric characteristics is enriched and clarified, thereby achieving a synergistic improvement in sensor performance. This work expands the application scope of microwave dielectric ceramics and provides an innovative approach to environmental monitoring. [ABSTRACT FROM AUTHOR]

Split-ring resonators (SRRs) and complementary split-ring resonators (CSRRs) are widely used in microwave devices. Considering its advantages of fluidity, high metallic conductivity, and extreme deformability, liquid metal is expected to enrich the tunability of SRR and CSRR. Here, a stretchable resonator based on CSRR, using liquid metal as the conducting layer and Ecoflex as the dielectric layer, is prepared by 3D printing. From the transmission spectra, we find that the resonant frequency can be continuously tuned from 3.77 to 3.40 GHz by stretching the resonator, which exhibits a stable quality factor, high ductility, excellent stretchability, and linearity. We then study the coupling between magnons in a yttrium iron garnet film and microwave photons in CSRRs. The anti-crossing effects are observed in transmission coefficient spectra by changing either the strength of the magnetic field or the size of the CSRR. The coupling strength g/2π is determined to be 63 MHz at a coupling frequency of 3.77 GHz and magnetic field of 800 Oe. Our findings could promote the development of reconfigurable metamaterials and cavity optomagnonics. [ABSTRACT FROM AUTHOR]

A sensor for the detection of glucose concentration in aqueous medium based on Tamm-Fano resonance is proposed in this research article. The presented sensor configuration mainly comprises of a thin layer of copper on top of a Distributed Bragg Reflector. Alternating layers of Gallium Arsenide with a high refractive index and Silicon dioxide with a low refractive index form the Distributed bragg reflector, respectively. For the detection of analyte such as glucose, a liquid cell has been introduced in between the Cu and Distributed bragg reflector structure. We used Ansys Lumerical software to analyse the sensor's near-infrared reflection spectrum (1000–2400 nm). The proposed sensor structure achieved a Sensitivity, Quality factor, Figure of Merit and Detection Limit of 831.32 nm/RIU, 152.52, 88.91 RIU−1 and 10–3 RIU, respectively. The proposed sensor structure shows promising results compared to the designs reported in the literature. The present study will be extremely useful for active and passive optoelectronic miniature devices in the future, making the proposed structure valuable not only for glucose detection but also for detecting a wide range of biomolecules and for gas sensing. [ABSTRACT FROM AUTHOR]

In this paper, carrier reservoir semiconductor optical amplifiers (CR-SOAs) are utilized for the first time in designing an all-optical 2 × 1 multiplexer with enable function, operating at 120 Gb/s. Traditional SOAs face challenges with slow carrier recovery, restricting their application in high-speed scenarios. CR-SOA, with a carrier reservoir near the active region, replenishes carriers quickly, enabling faster gain and phase recovery. For the first time, a 2 × 1 multiplexer with an enable input is proposed, adding flexibility and control for dynamic data routing in optical systems. Basic gates such as AND, OR, and NOT gates have been designed using this multiplexer, with the enable input enhancing their versatility. The performance of the multiplexer and gates is evaluated using metrics like quality factor, extinction ratio, contrast ratio, and eye opening factor. The quality factor is analyzed concerning parameters such as amplified spontaneous emission, data rate, carrier transition time, and injection current. Simulation results confirm the functionality of the 2 × 1 multiplexer and logic gates, demonstrating satisfactory performance at high data rates. [ABSTRACT FROM AUTHOR]

The article examines the relevance of piezoceramic spherical shell actuators, which provide a high level of accuracy and stability in the generation of vibrational oscillations over a wide range of amplitude-frequency characteristics. The spherical shape of these actuators is chosen because it allows for uniform distribution of mechanical stresses across the actuator's surface, thereby enhancing its durability and efficiency compared to traditional flat or cylindrical designs. The study presents analytically derived mathematical models and formulas for determining the electrical impedance of piezoelectric elements and analyzes the dependence of the amplitude of electrical impedance on frequency and the charge ratio on the polarized surfaces of the spherical piezoceramic element. The proposed model enables the determination of electrical impedance as a function of cyclic frequency and various parameters (geometric, physical and mechanical, electrical) of the actuators. The study establishes that spherical shell actuators exhibit a higher quality factor (2-2.5 times greater than disk actuators and 1.4-1.8 times greater than cylindrical actuators) and a significant reduction in impedance (2.5-7 times lower) at electromechanical resonance frequencies around 2.4 kHz. Furthermore, spherical actuators demonstrate 20-30 % better resistance to deformation and 15-25 % lower susceptibility to local resonances compared to other actuator shapes, which enhances operational stability and vibration generation accuracy. [ABSTRACT FROM AUTHOR]

A layered heterogeneous structure (LHS), consisting of silver, liquid crystal, and nonlinear dielectric layers, is proposed to realize functions of computing and sensing. By leveraging the optical Tamm state, the intrinsic absorption principle of liquid crystal, and nonlinear effects, the design of an integrated device capable of passive multiplication and division operations, along with high-performance multi-physical quantity sensing functionalities, is achieved. The given LHS exhibits Janus properties, with different physical functions manifested depending on the direction of electromagnetic wave (EW) propagation. During forward propagation of EWs, the LHS displays high and sharp absorptivity peaks at 774.8 and 1517.6 nm. The relationship between the two peaks approximates a frequency multiplication factor of 1.960, enabling signal multiplication. Furthermore, the two absorptivity peaks at different wavelengths facilitate the sensing of serum creatinine solution concentration and external pressure, with sensitivity (S), quality factors (Q), and figure of merit (FOM) of 266.76 μmol L−1/nm and 213.33 GPa/nm, as well as 248.76 and 348.22, 84.1 L (μmol)−1 and 49.06 GPa−1, respectively. During backward propagation of EWs, absorptivity peaks with distinct resolutions are observed at 1423 and 2809 nm, with a multiple relationship between them of 1.974, enabling frequency doubling for signal division. Additionally, the absorptivity curve facilitates temperature sensing over a wide range from 257 to 347 K. Owing to the unique temperature S of liquid crystal, different sensitivities and resolutions are observed at 257 to 297 K and 307 to 347 K, with S of 1.015 and 0.686 K/nm, and corresponding Q and FOM of 21.57 and 12.576, 0.076 K−1 and 0.003 04 K−1, respectively. [ABSTRACT FROM AUTHOR]

This article introduces a novel petal-like SAW topology insulator, which can transmit sound waves with low loss and high flexibility in an ultra-wide frequency band by simultaneously adjusting multiple structural parameters of phononic crystals. Using finite element analysis, it was found that adjusting these parameters can generate a broadband gap of 55.8–65.7 MHz. This structure can also achieve defect immunity and sharp bending in waveguide transmission. When this topology insulator is applied to resonators, compared to traditional designs, the insertion loss is reduced by 22 dB, the on-load quality factor is increased by 227%, the off-load quality factor is increased by 1024.5%, and the quality sensitivity is improved by 3.7 times compared to bare devices. [ABSTRACT FROM AUTHOR]

We propose a photonic crystal (PC) nanostructure that combines bound states In the continuum (BIC) with a high-quality factor up to 107 for emitting circularly polarized beams. We break the in-plane inversion symmetry of the unit cell by tilting the triangular hole of the hexagonal lattice, resulting in the conversion of a symmetrically protected BIC to a quasi-BIC. High-quality circularly polarized light is obtained efficiently by adjusting the tilt angles of the hole and the thickness of the PC layer. By changing the hole's geometry in the unit cell, the Q-factor of circularly polarized light is further improved. The quality factor can be adjusted from 6.0 × 103 to 1.7 × 107 by deliberately changing the shape of the holes. Notably, the proposed nanostructure exhibits a large bandgap, which significantly facilitates the generation of stable single-mode resonance. The proposed structure is anticipated to have practical applications in the field of laser technology, particularly in the advancement of low-threshold PC surface emitting lasers (PCSELs). [ABSTRACT FROM AUTHOR]

Soluble sugar content in apple fruit is a crucial internal quality factor. Rapid and accurate estimation of soluble sugar content in apple fruit is helpful to predicting maturity. However, few studies have used an approach of hyperspectral vegetation indexes for monitoring apple soluble sugar content from ground-based handheld hyperspectral data. This study systematically analyzed the performance of hyperspectral vegetation indexes of apple in estimating the soluble sugar content. The visible and near infrared spectral of apple samples were measured by using a hyperspectral equipment, with the wavelength of 350–2500 nm. Eleven early-ripening apple varieties were collected from orchards located in five provinces of China, and the sugar content of each apple fruit sample was measured using laboratory methods. Two-band combination method was used to identify the effective spectral index. Results showed that the newly developed two-band ratio spectral index R833/R834 (Rλ is the reflectance value at wavelength λ) was recommended as the optimal index for monitoring early-ripening apple soluble sugar content, generated the coefficients of determination, root mean square error (RMSE) and residual prediction deviation (RPD) values between the measured and predicted values of 0.73%, 0.72%, and 1.38%, respectively. Result indicated that the newly developed two-band index R833/R834 can be used to nondestructively determine apple fruit soluble sugar content. The findings can provide insight into the relationship between the optical properties of apple fruit at different wavelengths and soluble sugar content. [ABSTRACT FROM AUTHOR]

The discontinuous PWM technique, with its advantage over the continuous PWM technique in reducing switching losses in power converters, is gaining popularity. However, its deterministic nature results in discrete harmonics with significant amplitudes, which leads to electromagnetic interference (EMI) emissions. The randomised PWM technique is gaining more interest because of its effectiveness in spreading the harmonic spectrum and thus reducing EMI problems in power converters. This paper presents a carrier-based dual randomised discontinuous PWM (DRDPWM) method for a three-phase voltage inverter. The DRDPWM method combines the random carrier frequency (RCF-DPWM) and random pulse position (RPP-DPWM) schemes. In addition to reducing switching losses, DRDPWM can achieve a broad spread of the voltage spectrum with significantly smaller amplitudes. Furthermore, it produces less inverter output current distortion when compared to traditional DPWM and simple random (RCF-DPWM and RPP-DPWM) schemes. Simulations and experimental results confirm the effectiveness of the suggested method for spreading the voltage spectrum compared to simple random schemes. Additionally, an evaluation of the performance of all randomised discontinuous schemes is conducted based on a number of assessment metrics, including the switching loss factor (SLF), the power spectral density (PSD), the harmonic spread factor (HSF), and the quality factor (QF). [ABSTRACT FROM AUTHOR]

In this paper, we investigated the effect of processing parameters and composite regulation on the structure and property relationship of lightweight low‐permittivity Li2O–Al2O3–B2O3 dielectric system. Li2BAlO4 ceramic and (1 − x)Li2BAlO4–xSrTiO3 ceramics were synthesized using a conventional solid‐state reaction method. Thermodynamic analysis, sintering temperature, phase formation, crystal structure, and microwave dielectric properties were investigated. Thermal analysis revealed a melting temperature of 847°C, suggesting a comparatively low temperature for the sintering of Li2BAlO4 ceramics. Li2BAlO4 crystalized into a monoclinic structure with P21/c space group, with [Al2B2O8] rings connected by [BO3] triangles and [AlO4] tetrahedra through Al–O–Al bridges. Dense Li2BAlO4 ceramics with a relative density of ∼97.7% were sintered at 750°C and had optimal microwave dielectric properties with relative permittivity (εr) of 5.13, quality factor (Q × f) of 22 610 GHz, and the temperature coefficient of resonance frequency (τf) of −112.5 ppm/°C. The 0.88Li2BAlO4–0.12SrTiO3 composite ceramic has excellent microwave dielectric properties with εr = 8.83, Q × f = 14 000 GHz, τf = 4.6 ppm/°C. The ceramics also demonstrated an inert behavior with silver electrodes proving its application in low‐temperature cofired ceramic (LTCC) technology. [ABSTRACT FROM AUTHOR]

This paper presents a novel multiple-input single-output current-mode shadow filter and oscillator using current-controlled current conveyors (CCCIIs). The CCCII current gains are used to set the filter's quality factor and natural frequency. The filter is resistorless with grounded capacitors, making it more suitable for integration. The filter offers low-pass, high-pass, band-pass, band-stop and all-pass transfer functions in a single topology by appropriately applying the input signals. To validate the functionality of the new topology, the proposed circuit is simulated by SPICE using bipolar transistors arrays AT&T ALA400-CBIC-R. [ABSTRACT FROM AUTHOR]

Given the widespread adoption of fresh food e-commerce, this study aimed to explore the service quality attributes influencing utilitarian value, hedonic value, and impulsive buying behavior. A survey was conducted with 263 participants who had experience in purchasing fresh food online. Their responses were analyzed to test hypotheses using structural equation modeling. The findings reveal significant influences of information quality, ease of use, and problem resolution on utilitarian value. Additionally, ease of use, problem resolution, and trendiness were found to impact hedonic value. Problem resolution was a quality factor that affected both practical value and hedonic value, and its influence was found to be greater than that of other service quality factors. Hedonic value was also found to significantly affect impulsive buying behavior; however, utilitarian value did not exhibit a significant impact on impulsive buying behavior. The results provide useful theoretical and managerial implications in the field of fresh food e-commerce business. [ABSTRACT FROM AUTHOR]

The relation between the improvement of mechanical quality factor (Qm) and internal electric field (Ei) generated during the aging process in lead‐free piezoelectric BiFeO3‐BaTiO3 ceramics is investigated for hard piezoelectric application of power transducers. The change of built‐in Ei depends on the ferroelectric polarization (P) direction during the aging process. For the aging process with P parallel to Ei, Qm and Ei increases but Qm and Ei decreases with P antiparallel to Ei. These results are attributed to the migration of defects by depolarization fields and domain‐wall pinning. This work provides the systematic guidance to develop high‐power piezoelectric transducers with lead‐free ceramics. [ABSTRACT FROM AUTHOR]

Purpose: Internal communication in municipal offices is an important factor that affects the quality of the services provided by this organisation. The article uses factor analysis to identify the quality factors of internal communication between front-office and back-office staff and, on this basis, identifies problems in this communication and also proposes improvement measures. Design/methodology/approach: The paper identifies latent factors of the quality of internal communication between front-office and back-office employees of a selected municipal office. The identified factors were used to assess the level of internal communication quality between front-office and back-office employees. Findings: Based on factor analysis, latent factors of the quality of internal communication between front-office and back-office employees were identified and, on this basis, the level of quality of internal communication between the surveyed municipal office employees was assessed and problems in this communication were identified. Research limitations/implications: The main limitation of the article is that it is based on one case of an organisation. Future research will need to be conducted in more organisations to find out whether the same result can be achieved. Practical implications: The research conducted identified three latent factors of the quality of internal communication between front-office and back-office staff in one municipal office. These factors include: cooperation between front-office and back-office staff, assurance and responsiveness. The identified factors were used to assess the level of quality of internal communication between front-office and back-office staff. The worst-rated factor is collaboration between the employees surveyed (2.26), better assurance (3.67), while responsiveness is the best (3.97). Originality/value: To date, the level of quality of internal communication between front-office and back-office employees has not been assessed in municipal offices. It is difficult to find research results in the system that are effective and effectively ensure the effectiveness of communication between front-office and back-office employees. [ABSTRACT FROM AUTHOR]

TEM00-mode operation is a requirement in many laser-based applications due to the small divergence and high-power density of the emitted laser beam. A solar laser scheme was designed and numerically studied with the goal of increasing the solar-to-laser power conversion efficiency in the TEM00-mode operation. The collection and primary concentration of sunlight was performed via twelve sets of folding mirrors and Fresnel lenses, toward a laser head composed of a fused silica torus volume and seven Ce:Nd:YAG rods, in a side-pump configuration. With this scheme, TEM00-mode laser power totaling 212.39 W could potentially be produced from seven beams, with six of them being 32.60 W each and with M x 2 = 1.00,   M y 2 = 1.01 quality factors. Notably, 35.40 W/m2 collection efficiency and, most importantly, 3.73% solar-to-laser power conversion efficiency were numerically achieved. The latter efficiency value represents a 1.81-time improvement over the experimental record, established with a prototype that had a single Ce:Nd:YAG rod in an end-side pump configuration. [ABSTRACT FROM AUTHOR]

The study of localized surface plasmons (LSPs) in nanoscale structures is an essential step towards identifying optimal plasmonic modes that can facilitate robust optomechanical coupling and deepen our understanding of light–matter interactions at the nanoscale. This paper investigates, numerically, using the finite element method, LSP modes in a design comprising two coupled nano-ridges deposited on a gold layer with an interposing polymer spacer layer. Such a structure, usually referred to as a particle-on-mirror structure, shows exquisite optical properties at the nanoscale. We first examine the LSP modes of a single nano-ridge through the analysis of its scattering cross-section in the visible and infrared ranges. To enhance the plasmonic response, a thin polymer layer is placed at the middle of the ridge, which introduces additional LSP modes confined within the former. Then, we extend the analysis to the dimer configuration, which exhibits more complex and enhanced plasmonic behavior compared to a single nano-ridge. In particular, the dimer configuration yields LSP resonances with a quality factor enhancement of approximately threefold relative to a single nano-ridge. Furthermore, the presence of the polymer layer within the ridges significantly improves plasmon field localization and the quality factor. These findings underscore the potential of nano-ridge-based structures in advancing optomechanical coupling and offering valuable insights for the development of high-performance acousto-plasmonic devices. In particular, the proposed device could help significantly improve the design of nano-acousto-optic modulators, operating in the visible or in the near-infrared ranges, that require an enhanced light–phonon coupling rate. [ABSTRACT FROM AUTHOR]

The paper presents a model of an open resonator exhibiting a single high-Q eigen oscillation within a one-octave frequency band. The resonator is synthesized by integrating a diffraction radiation antenna, which comprises a segment of a dielectric waveguide above a metal substrate with a diffraction grating, into a system of flat reflectors aligned parallel to the wave fronts of surface and bulk waves generated by the antenna. A pulse response with an amplitude-frequency characteristic featuring one pronounced resonant maximum, which corresponds to an eigen oscillation with Q factor exceeding 104 , has been achieved in the proposed system. The optical length of the resonator exceeds the wavelength of the working oscillation by over 50 times. The feasibility of tuning the resonator via moving both the mirrors and the diffraction grating is demonstrated. The proposed model holds promise for applications in the development of solid-state and quantum radiation sources operating in the microwave and higher frequency ranges. [ABSTRACT FROM AUTHOR]

This research explores Wavelength Division Multiplexing Passive Optical Networks (WDM-PON) with Erbium-Doped Fiber Amplifier (EDFA) to meet the growing demand for highbandwidth applications. Using Optsim software, the proposed system is simulated for 4-channels WDMPON. The paper presents a comparison of WDMPON performance with and without EDFA amplifiers. It is to be proven that in inclusion of EDFA in the WDM-PON system will significantly improve the system's output power, reduce bit error rate (BER) and enhance the quality factor (Q-factor) with enhanced input parameters like higher fiber length up to 50 Km. The area of EDFA will also be optimized for improving system performance. The bitrate will also be increased to meet modern requirements of higher bandwidth. With EDFA, the WDM-PON system will perform better in the terms of error rate and signal amplification. The design involves parameters like bitrate, laser power, fiber length, modulation type, attenuated power, etc. WDM-PON with EDFA shows great potential for applications like high-speed data transmission systems for Internet applications. System is to be designed for higher bitrate with dispersion compensation and higher fiber length. The Goal is to achieve lower BER even at high distance of communication. [ABSTRACT FROM AUTHOR]

Unwanted signals in electrical systems frequently overpower the desired signal. In an attempt to increase the ratio, the desired signals are amplified proportionately to the undesired ones. Frequency selective circuits, often known as filters, can be used to separate desired signals from undesirable ones as signals can be identified by their frequency characteristics. Analog filters are available in both active and passive varieties, each having unique properties. A first order band pass active filter is developed and characterized in this study. The Operational Amplifier (OP AMP 741) is the active element in this case. With the Band Width (BW), Cut-off Frequencies (FL and FH), Center Frequency (FC), and Quality factor (Q) provided, the Transfer Function (TF) equation is generated and defined. [ABSTRACT FROM AUTHOR]

We present waveguide cavity measurements used to evaluate several thin materials for use in radomes. In addition to the data on the materials, we show how these measurements can be performed with common laboratory equipment and simple calculations. We sought an approach that allowed candidate materials to be readily evaluated to deal with formerly selected materials becoming unavailable or cost-prohibitive. We used lengths of standard waveguide (WR650 and WR137 here) with readily manufactured irises and a vector network analyzer (Keysight N5225B here). To select the iris size and determine the limits of the simplifications in the equations used, we employed a full-wave 3D electromagnetic simulator (CST Microwave Studio). The equations required to calculate the dielectric properties of samples and their contribution to the equivalent system noise temperature from unloaded and loaded resonant frequencies and Q factors are shown. While these formulations can be found elsewhere, we did not find these assembled as conveniently in other studies in the literature. We also show that orienting the sample down the length of the cavity allows for higher-order modes to be fully utilized. We did not find this straightforward adaptation of the common cross-guide orientation in other works. Overall, the results allowed us to recommend three fabrics for use at the frequencies tested (1.7 and 5.6 GHz). The complete process is outlined to assist others in performing these measurements themselves. [ABSTRACT FROM AUTHOR]

Linear particle accelerators (Linacs) are primarily composed of radio frequency cavities (cavities). Compared to traditional manufacturing, Laser Powder Bed Fusion (L-PBF) holds the potential to fabricate cavities in a single piece, enhancing Linac performance and significantly reducing investment costs. However, the question of whether red or green laser PBF yields superior results for pure copper remains a subject of ongoing debate. Eight 4.2 GHz single-cell cavities (SCs) were manufactured from pure copper using both red and green PBF (SCs R and SCs G). Subsequently, the surface roughness of the SCs was reduced through a chemical post-processing method (Hirtisation) and annealed at 460 °C to maximize their quality factor ( Q 0 ). The geometric accuracy of the printed SCs was evaluated using optical methods and resonant frequency ( f R ) measurements. Surface conductivity was determined by measuring the quality factor ( Q 0 ) of the SCs. Laser scanning microscopy was utilized for surface roughness characterization. The impact of annealing was quantified using Energy-Dispersive X-ray Spectroscopy and Electron Backscatter Diffraction to evaluate chemical surface properties and grain size. Both the SCs R and SCs G achieved the necessary geometric accuracy and thus f R precision. The SCs R achieved a 95% Q 0 after a material removal of 40 µm. The SCs G achieved an approximately 80% Q 0 after maximum material removal of 160 µm. Annealing increased the Q 0 by an average of about 5%. The additive manufacturing process is at least equivalent to conventional manufacturing for producing cavities in the low-gradient range. The presented cavities justify the first high-gradient tests. [ABSTRACT FROM AUTHOR]

High-permittivity Ba(Eu1/5Sm1/5Nd1/5Pr1/5La1/5)2Ti4O12 (BESNPLT) high-entropy ceramics (HECs) were synthesized via a solid-state route. The microstructure, sintering behavior, phase structure, vibration modes, and microwave dielectric characteristics of the BESNPLT HECs were thoroughly investigated. The phase structure of the BESNPLT HECs was confirmed to be a single-phase orthorhombic tungsten-bronze-type structure of Pnma space group. Permittivity (εr) was primarily influenced by polarizability and relative density. The quality factor (Q×f) exhibited a significant correlation with packing fraction, whereas the temperature coefficient (TCF) of the BESNPLT HECs closely depended on the tolerance factor and bond valence of B-site. The BESNPLT HECs sintered at 1400 °C, demonstrating high relative density (>97%) and optimum microwave dielectric characteristics with TCF = +38.9 ppm/°C, Q×f = 8069 GHz (@6.1 GHz), and εr = 87.26. This study indicates that high-entropy strategy was an efficient route in modifying the dielectric characteristics of tungsten-bronze-type microwave ceramics. [ABSTRACT FROM AUTHOR]

Terahertz (THZ) spectroscopy has emerged as a superior label-free sensing technology in the detection, identification, and quantification of biomolecules in various biological samples. However, the limitations in identification and discrimination sensitivity of current methods impede the wider adoption of this technology. In this article, a meticulously designed metasurface is proposed for molecular fingerprint enhancement, consisting of a periodic array of lithium tantalate triangular prism tetramers arranged in a square quartz lattice. The physical mechanism is explained by the finite-difference time-domain (FDTD) method. The metasurface achieves a high quality factor (Q-factor) of 231 and demonstrates excellent THz sensing capabilities with a figure of merit (FoM) of 609. By varying the incident angle of the THz wave, the molecular fingerprint signal is strengthened, enabling the highly sensitive detection of trace amounts of analyte. Consequently, cinnamoylglycine can be detected with a sensitivity limit as low as 1.23   μ g · c m − 2 . This study offers critical insights into the advanced application of THz waves in biomedicine, particularly for the detection of urinary biomarkers in various diseases, including gestational diabetes mellitus (GDM). [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) is a short-range optical wireless communication technology that attempts to achieve communication alongside illumination using existing infrastructure in the band of 430–790 THz. One of the crucial research gaps in VLC is the absence of an experimental evaluation of performance metric parameters like zero frequency (DC) channel gain, received power, bit error rate (BER) and signal-to-noise ratio at divergent wavelengths and luminous intensities for different optical output power levels. The second research gap is the need for an empirical formulation to estimate the BER for a defined data rate and luminous intensity of the light emitting diode (LED). The objective of this experimental work is to bridge the above two research gaps under a realistic illumination setup. The first gap is addressed by analyzing the impact of divergent output optical power levels of LEDs having different values of luminous intensities and wavelength on QoS parameters. The quality of service (QoS) parameters like transmitted optical power, received optical power, DC gain, quality factor and BER are evaluated and analyzed at a data rate of 1.2 Mbps for a maximum distance of 1 m. The work also evaluates the band of forward LED currents in the range of 12–20 mA to achieve a minimum BER of 10−5–10−7 for a maximum distance of 1 m. The second research gap is worked on by proposing a novel mathematical empirical formulation using fifth-order polynomial curve fitting to estimate the bit error rate (BER) by considering factors of luminous intensity and data rate for a maximal distance of 1 m. The empirical formulation is done using Microsoft EXCEL2010® and MATLAB2023®. [ABSTRACT FROM AUTHOR]

This study introduces the creation, simulation, and assessment of a 2-D photonic crystal refractive index biomedical sensor, enriched with intricate design considerations. The focal point of the design process revolves around achieving exceptional sensitivity, high-quality factor, and an impressively compact multi-type cancer sensor. The proposed approach involves the development of a nanocavity photonic crystal waveguide, embellished with double circle hole defects and an arrangement of silicon rods in a hexagonal lattice pattern. This sensor is designed to effectively differentiate between normal cells and six distinct categories of cancerous cells, namely Jurkat, Hela, PC-12, MDA-MB-231, MCF-7, and Basal (which pertains to skin cancer). The proposed design provide remarkable sensitivity, ultra-quality factor and compactness for healthy cell 455.33 nm/RIU, 7199.86, 9.4 × 5.5 µm2 respectively. The investigation employs both the finite difference time domain method and the plane wave expansion methods to meticulously analyze and simulate the suggested biosensor design. Furthermore, a comprehensive comparative analysis is conducted, between the current work with literature concerning cancer-centric refractive index photonic crystal sensors. This endeavor is undertaken to validate and underscore the credibility and efficacy of the proposed design. [ABSTRACT FROM AUTHOR]

The work describes design and simulations of a three input NAND gate using quantum dot semiconductor optical amplifiers for the first time as far as author's knowledge goes. Both cross gain modulation and cross phase modulations implement the NAND operation in a modified manner. Amplitude modulation, extinction ratio, relative eye opening, contrast ratio, etc. are optimized in terms of control power and their dependence on amplified spontaneous noise has been investigated for three different unsaturated gains of the QDSOA. These parameters show efficient performance for unsaturated gains 20 and 30 dB. REO value more than 99% and Q value more than 16 dB ensure practical feasibility of the logic gate proposed. [ABSTRACT FROM AUTHOR]

On-chip photonic devices based on SiO 2 are of interest for applications such as microresonator gyroscopes and microwave sources. Although SiO 2 microdisk resonators have achieved quality factors exceeding one billion, this value remains an order of magnitude less than the intrinsic limit due to surface roughness scattering. Atomic layer etching (ALE) has potential to mitigate this scattering because of its ability to smooth surfaces to sub-nanometer length scales. While isotropic ALE processes for SiO 2 have been reported, they are not generally compatible with commercial reactors, and the effect on surface roughness has not been studied. Here, we report an ALE process for SiO 2 using sequential exposures of Al(CH3)3 (trimethylaluminum) and Ar/H2/SF6 plasma. We find that each process step is self-limiting, and that the overall process exhibits perfect synergy, with neither isolated half-cycle resulting in etching. We observe etch rates up to 0.58 Å per cycle for thermally grown SiO 2 and higher rates for ALD, plasma enhanced chemical vapor deposition, and sputtered SiO 2 up to 2.38 Å per cycle. Furthermore, we observe a decrease in surface roughness by 62% on a roughened film. The residual concentration of Al and F is around 1%–2%, which can be further decreased by O2 plasma treatment. This process could find applications in smoothing of SiO 2 optical devices and thereby enabling device quality factors to approach limits set by intrinsic dissipation. [ABSTRACT FROM AUTHOR]

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In this paper, we investigated the effect of processing parameters and composite regulation on the structure and property relationship of lightweight low‐permittivity Li2O–Al2O3–B2O3 dielectric system. Li2BAlO4 ceramic and (1 − x)Li2BAlO4–xSrTiO3 ceramics were synthesized using a conventional solid‐state reaction method. Thermodynamic analysis, sintering temperature, phase formation, crystal structure, and microwave dielectric properties were investigated. Thermal analysis revealed a melting temperature of 847°C, suggesting a comparatively low temperature for the sintering of Li2BAlO4 ceramics. Li2BAlO4 crystalized into a monoclinic structure with P21/c space group, with [Al2B2O8] rings connected by [BO3] triangles and [AlO4] tetrahedra through Al–O–Al bridges. Dense Li2BAlO4 ceramics with a relative density of ∼97.7% were sintered at 750°C and had optimal microwave dielectric properties with relative permittivity (εr) of 5.13, quality factor (Q × f) of 22 610 GHz, and the temperature coefficient of resonance frequency (τf) of −112.5 ppm/°C. The 0.88Li2BAlO4–0.12SrTiO3 composite ceramic has excellent microwave dielectric properties with εr = 8.83, Q × f = 14 000 GHz, τf = 4.6 ppm/°C. The ceramics also demonstrated an inert behavior with silver electrodes proving its application in low‐temperature cofired ceramic (LTCC) technology. [ABSTRACT FROM AUTHOR]

In this work, we discuss and experimentally investigate the whispering gallery modes (WGMs) in a 500 μm radius silicon sphere. We begin by reviewing the basics of WGM resonators, followed by simulations and experimental results obtained with the aforementioned silicon spherical WGM resonator. The recorded WGM signatures in the transmission and scattering spectra excited, in the near-infrared (near-IR) region, agree well with the simulations. Thermo-optic tuning of these WGMs is achieved by introducing a pump laser in the violet-blue region. Red-shifts in wavelength are observed, which increase with the increase in the pump power. A shift of 0.63 nm is observed at a pump power of 6.32 mW. We also study switching by analysing the transient response of the WGM spectra. The measured WGMs exhibit high quality factors ($Q\sim 10^5$Q∼105), which along with the aforesaid tunability, demonstrates the potential of spherical silicon resonator as a platform for photonic applications, e.g. sensing and communication. In summary, this work contributes towards the understanding of the fundamental physics of WGMs and provides insights into silicon WGM resonators. [ABSTRACT FROM AUTHOR]

AlGaAs is a promising integrated nonlinear photonics material with enormous optical nonlinearity and high refractive index. Nevertheless, presently AlGaAs microring resonators exhibiting high-quality factors and tight optical confinement rely predominantly on wafer bonding techniques, which entail an intricate fabrication process. Here, we present suspended AlGaAs waveguides and resonators as a viable platform for high efficiency integrated nonlinear photonics. The suspended microring resonator formed by combined plasma dry etching and chemical wet etching exhibits an intrinsic quality factor Q of 2.1 × 10 6 , corresponding to an optical loss of 0.28 dB/cm, and Kerr comb generation with milliwatt level threshold is recorded. The proposed scheme can be implemented with a relatively simple fabrication process, as it eliminates the need for wafer bonding. Without the hinderance of SiO 2 or Al 2 O 3 claddings, the air-clad suspended AlGaAs platform lends itself directly to applications in the mid-infrared region. Our demonstration opens up a prospect for employing AlGaAs devices in integrated nonlinear photonics. [ABSTRACT FROM AUTHOR]

Resonant nanostructures have emerged as versatile photonic platforms for boosting optical nonlinear responses on a subwavelength scale for their ability to confine intense electromagnetic fields while relaxing the phase-matching requirements. Recent significant advances in this field are associated with the utilization of non-radiative eigenmodes above the light cone, termed bound states in the continuum (BICs), which provide a unique mechanism for light trapping to realize excitation of ultrahigh quality (Q) factor resonances. Nevertheless, the current studies on BICs predominantly focus on symmetry-protected BICs (SP-BICs), whose excitation requires symmetry breaking, and Q factors are limited by fabrication imperfections. Here, we demonstrate a simple and feasible scheme for creating degenerate pairs of mirror-coupled super-BICs by harnessing magnetic dipole resonances coupled to their mirror images in adjacent metal films. Unlike trivial SP-BICs, mirror-coupled BICs showcases the huge enhancement of Q factors and are resilient against fabrication imperfections. By combining mirror-coupled resonance with the engineered radiative loss, we obtain a perfect absorber with near-unity absorption and ultra-narrow bandwidth at a critical coupling condition. Finally, we numerically demonstrate the terahertz (THz) regime, polarization-insensitive highly efficient third-harmonic generation benefiting from the maximum field enhancement localized within the perfect absorber. Our work not only paves the way toward unlocking the full potential of BIC resonance but also promise valuable insights for developing efficient THz optoelectronic devices and metadevices across a wide range of fields. [ABSTRACT FROM AUTHOR]

The current investigation theoretically presents a one-dimensional phononic crystal (PnC) as a fluidic sensor. The sensor under consideration aims to distinguish the concentration of acetic acid. The primary configuration of the proposed sensor is constructed with lead, epoxy, and a defect layer in the middle of the structure, that is filled with acetic acid (vinegar). As a result of the rise in density and decline in the speed of sound at a 100% concentration of acetic acid in comparison to pure water, the peak frequency of the output has shifted towards lower frequencies. Given that the maximum permissible concentration of acetic acid in water for vinegar is above 30%, sensor simulations were conducted within the concentration range of 25–35% with a step size of 1%. Interestingly, the sensitivity of the sensor exhibits a polynomial change in response to the concentration of acetic acid. Consequently, the highest level of sensitivity, which corresponds to the lowest concentration of vinegar, is recorded as 48.44 × 106 (Hz). The proposed system exhibits a remarkable value of the quality factor of 2802.91. Furthermore, the optimal figure of merit (FOM) is achieved when the concentration is at its lowest, with a value of 94.00. Furthermore, the temperature effects are taken into account for a wide range between 10 and 60 °C. A pronouncing sensitivity is obtained for all temperatures changes and the highest one reached the value of 1.57 × 106 (Hz/°C) at a temperature of 25 °C. Considering the present circumstances, the suggested sensor configuration has the potential to cater to a diverse array of other fluids, specifically their concentration and temperature, thereby offering a broad scope of applications. [ABSTRACT FROM AUTHOR]

Exploring the mysterious dark matter is a key quest in modern physics. Currently, detecting axions, a hypothetical particle proposed as a primary component of dark matter, remains a significant challenge due to their weakly interacting nature. Here we show at quantum level that in a cavity permeated by a magnetic field, the single axion-photon conversion rate is enhanced by the cavity quality factor and is quantitatively larger than the classical result by π/2. The axion cavity can be considered a quantum device emitting single photons with temporal separations. This differs from the classical picture and reveals a possibility for the axion cavity experiment to handle the signal sensitivity at the quantum level, e.g., a dual path quantum interferometry with cross-power and second-order correlation measurements. This scheme would greatly reduce the signal scanning time and improve the sensitivity of the axion-photon coupling, potentially leading to the direct observation of axions. Axions are the top contenders for explaining the enigmatic dark matter in the Universe. The authors present the inaugural quantum-level validation of a cavity's resonant boost to the conversion of axions into photons, thus employing a dual-path interferometry method can greatly enhance the signal-to-noise ratio in the experiments, enabling swifter scans and a better detection sensitivity for the evasive axion dark matter. [ABSTRACT FROM AUTHOR]

Extremely low‐frequency (ELF) electromagnetic (EM) waves adeptly propagate in harsh cross‐medium environments, overcoming rapid decay that hinders high‐frequency counterparts. Traditional antennas, however, encounter challenges concerning size, efficiency, and power. Here, drawing inspiration from nature, we present a groundbreaking piezo‐actuated, bionic flapping‐wing magnetic‐dipole resonator (BFW‐MDR), operating in the electro‐mechano‐magnetic coupling mechanism, designed for efficient ELF EM wave transmission. The unique rigid‐flexible hybrid flapping‐wing structure magnifies rotation angles of anti‐phase magnetic dipoles by tenfold, leading to constructive superposition of emitted magnetic fields. Consequently, the BFW‐MDR exhibits a remarkable quality factor of 288 and an enhanced magnetic field emission of 514 fT at 100 meters with only 6.9 mW power consumption, surpassing traditional coil antennas by three orders of magnitude. The communication rate is doubled by the ASK+PSK modulation method. Its robust performance in cross‐medium communication, even amidst various interferences, underscores its potential as a highly efficient antenna for underwater and underground applications. [ABSTRACT FROM AUTHOR]

In classical guitar acoustic spectra, the lowest frequency body mode's amplitude often significantly surpasses that of the string overtones. However, the characteristics of the body mode have not been systematically utilized to quantitatively represent the timbre of classical guitars. In this study, we propose a quantitative method for describing the body mode, which can effectively differentiate the timbre of classical guitars. Our approach involves three key parameters presented in a three-dimensional space, as follows: the frequency and quality factors of the body mode, along with the amplitude ratio of the plucked string note to the body mode in the soundboard's vibration spectrum. This representation allows for the visualization, quantitative comparison, and classification of the body mode note and damping properties across classical guitars. The differences in body mode among guitars can be analyzed quantitatively using Euclidean distance. [ABSTRACT FROM AUTHOR]

The microstructure of concrete can be affected by many factors, from non-destructive environmental factors through to destructive damage induced by transient stresses. Coda wave interferometry is a technique that is sensitive enough to detect weak changes within concrete by evaluating the ultrasonic signal perturbation compared to a reference state. As concrete microstructure is sensitive to many factors, it is important to separate their contributions to the observables. In this study, we characterize the relationships between the concrete elastic and inelastic properties, and temperature and relative humidity. We confirm previous theoretical studies that found a linear relationship between temperature changes and velocity variation of the ultrasonic waves for a given concrete mix, and provide scaling factors per Kelvin for multiple settings. We also confirm an anti-correlation with relative humidity using long-term conditioning. Furthermore, we explore beyond the existing studies to establish the relationship linking humidity and temperature changes to ultrasonic wave attenuation. [ABSTRACT FROM AUTHOR]

This study focuses on the synthesis and characterization of Ca 0.6 Sr 0.4-x Ba x ZrO 3 (x = 0.01, 0.04, 0.07, and 0.10) ceramics prepared via the solid-state method and sintered at 1450 °C. The impact of Sr substitution by Ba at the A-site of the perovskite structure on crystalline properties and microwave dielectric performance was investigated. The experimental results show the formation of a single-phase structure, Ca 0.612 Sr 0.388 ZrO 3 (CSZ), across the entire range of x values. It is evident that the Ca 0.6 Sr 0.39 Ba 0.01 ZrO 3 ceramics exhibits the highest sintering density and the lowest porosity. These ceramics exhibit impressive dielectric properties, including a high permittivity of 28.38, low dielectric loss of 4.0×10−4, and a Q factor value of 22988 at 9–10 GHz. The research reveals that the influences of Sr substitution by Ba in enhancing the microwave dielectric properties of Ca 0.612 Sr 0.388 ZrO 3 ceramics, and the impedance curves clearly showed effects on the electrical properties. [ABSTRACT FROM AUTHOR]