Search Results (316)

To improve the efficiency and stability of the system, this paper proposes a monolithic integrated optical path design for a cavity optomechanical accelerometer based on a 250 nm top silicon thickness silicon-on-insulator (SOI) wafer instead of readout through U-shape fiber coupling. Finite Element Analysis (FEA) and Finite-Difference Time-Domain (FDTD) methods are employed to systematically investigate the performance of key optical structures, including the resonant modes and bandgap characteristics of photonic crystal (PhC) microcavities, transmission loss of strip waveguides, coupling efficiency of tapered-lensed fiber-to-waveguide end-faces, coupling characteristics between strip waveguides and PhC waveguides, and the coupling mechanism between PhC waveguides and microcavities. Simulation results demonstrate that the designed PhC microcavity achieves a quality factor (Q-factor) of 2.26 × 10⁵ at a 1550 nm wavelength while the optimized strip waveguide exhibits a low loss of merely 0.2 dB over a 5000 μm transmission length. The strip waveguide to PhC waveguide coupling achieves 92% transmittance at the resonant frequency, corresponding to a loss below 0.4 dB. The optimized edge coupling structure exhibits a transmittance of 75.8% (loss < 1.2 dB), with a 30 μm coupling length scheme (60% transmittance, ~2.2 dB loss) ultimately selected based on process feasibility trade-offs. The total optical path system loss (input to output) is 5.4 dB. The paper confirms that the PhC waveguide–microcavity evanescent coupling method can effectively excite the target cavity mode, ensuring optomechanical coupling efficiency for the accelerometer. This research provides theoretical foundations and design guidelines for the fabrication of high-precision monolithic integrated cavity optomechanical accelerometers. Full article

Highly integrable silicon carbide (SiC) has emerged as a promising platform for photonic integrated circuits (PICs), offering a comprehensive set of material and optical properties that are ideal for the integration of nonlinear devices and solid-state quantum defects. However, despite significant progress in nanofabrication technology, the development of SiC on an insulator (SiCOI)-based photonics faces challenges due to fabrication-induced material optical losses and complex processing steps. An alternative approach to mitigate these fabrication challenges is the direct deposition of amorphous SiC on an insulator (a-SiCOI). However, there is a lack of systematic studies aimed at producing high optical quality a-SiC thin films, and correspondingly, on evaluating and determining their optical properties in the telecom range. To this end, we have studied a single-source precursor, 1,3,5-trisilacyclohexane (TSCH, C₃H₁₂Si₃), and chemical vapor deposition (CVD) processes for the deposition of SiC thin films in a low-temperature range (650–800 °C) on a multitude of different substrates. We have successfully demonstrated the fabrication of smooth, uniform, and stoichiometric a-SiCOI thin films of 20 nm to 600 nm with a highly controlled growth rate of ~0.5 Å/s and minimal surface roughness of ~5 Å. Spectroscopic ellipsometry and resonant micro-photoluminescence excitation spectroscopy and mapping reveal a high index of refraction (~2.7) and a minimal absorption coefficient (<200 cm⁻¹) in the telecom C-band, demonstrating the high optical quality of the films. These findings establish a strong foundation for scalable production of high-quality a-SiCOI thin films, enabling their application in advanced chip-scale telecom PIC technologies. Full article

This research presents the development and management principles of mobile resonant electrical systems designed for high-voltage generation, intended for non-destructive diagnostics of insulation in high-power electrical equipment. The core of the system is a series inductive–capacitive (LC) circuit characterized by a high quality (Q) factor and operating at high frequencies, typically in the range of 40–50 kHz or higher. Practical implementations of the LC circuit with Q-factors exceeding 200 have been achieved using advanced materials and configurations. Specifically, ceramic capacitors with a capacitance of approximately 3.5 nF and Q-factors over 1000, in conjunction with custom-made coils possessing Q-factors above 280, have been employed. These coils are constructed using multi-core, insulated, and twisted copper wires of the Litzendraht type to minimize losses at high frequencies. Voltage amplification within the system is effectively controlled by adjusting the current frequency, thereby maximizing voltage across the load without increasing the system’s size or complexity. This frequency-tuning mechanism enables significant reductions in the weight and dimensional characteristics of the electrical system, facilitating the development of compact, mobile installations. These systems are particularly suitable for on-site testing and diagnostics of high-voltage insulation in power cables, large rotating machines such as turbogenerators, and other critical infrastructure components. Beyond insulation diagnostics, the proposed system architecture offers potential for broader applications, including the charging of capacitive energy storage units used in high-voltage pulse systems. Such applications extend to the synthesis of micro- and nanopowders with tailored properties and the electrohydropulse processing of materials and fluids. Overall, this research demonstrates a versatile, efficient, and portable solution for advanced electrical diagnostics and energy applications in the high-voltage domain. Full article

In this study, the influence of HfO₂ interlayer thickness on the performance of heteroepitaxial α-Ga₂O₃ layer-based metal–insulator–semiconductor–insulator–metal (MISIM) ultraviolet photodetectors is examined. A thin HfO₂ interlayer enhances the interface quality and reduces the density of interface traps, thereby improving the performance of UVC photodetectors. The fabricated device with a 1 nm HfO₂ interlayer exhibited a significantly reduced dark current and higher photocurrent than a conventional metal–semiconductor–metal (MSM). Specifically, the 1 nm HfO₂ MISIM device demonstrated a photocurrent of 2.3 μA and a dark current of 6.61 pA at 20 V, whereas the MSM device exhibited a photocurrent of 1.1 μA and a dark current of 73.3 pA. Furthermore, the photodetector performance was comprehensively evaluated in terms of responsivity, response speed, and high-temperature operation. These results suggest that the proposed ultra-thin HfO₂ interlayer is an effective strategy for enhancing the performance of α-Ga₂O₃-based UVC photodetectors by simultaneously suppressing dark currents and increasing photocurrents and ultimately demonstrate its potential for stable operation under extreme environmental conditions. Full article

Despite notable advancements in smart home technologies, residential energy management continues to face critical challenges. These include the complex integration of intermittent renewable energy sources, issues related to data latency, interoperability, and standardization across diverse systems, the inflexibility of centralized control architectures in dynamic environments, and the difficulty of accurately modeling and influencing occupant behavior. To address these challenges, this study proposes an intelligent multi-agent system designed to accurately estimate and control energy consumption in residential buildings, with the overarching objective of optimizing energy usage while maintaining occupant comfort and satisfaction. The methodological approach employed is a hybrid framework, integrating multi-agent system architecture with system dynamics modeling and agent-based modeling. This integration enables decentralized and intelligent control while simultaneously simulating physical processes such as heat exchange, insulation performance, and energy consumption, alongside behavioral interactions and real-time adaptive responses. The system is tested under varying conditions, including changes in building insulation quality and external temperature profiles, to assess its capability for accurate control and estimation of energy use. The proposed tool offers significant added value by supporting real-time responsiveness, behavioral adaptability, and decentralized coordination. It serves as a risk-free simulation platform to test energy-saving strategies, evaluate cost-effective insulation configurations, and fine-tune thermostat settings without incurring additional cost or real-world disruption. The high fidelity and predictive accuracy of the system have important implications for policymakers, building designers, and homeowners, offering a practical foundation for informed decision making and the promotion of sustainable residential energy practices. Full article

Topological insulators (TIs) hold considerable promise for the advancement of optoelectronic technologies, including spectroscopy, imaging, and communication, owing to their remarkable optical and electrical characteristics. This study proposes a novel combination of Bi${}_2$Se${}_3$ TIs and ReSe${}_2$ for self-powered broadband photodetectors with high sensitivity and fast response time. The Bi${}_2$Se${}_3$/ReSe${}_2$ heterojunction photodetector achieves broadband response spectra ranging for 375 nm to 1 $\mathsf{\mu }$m. It demonstrates a significant responsivity of 64 mA/W at a wavelength of 600 nm (1 mW/cm${}^2$), exhibits a rapid response speed of 345 $\mathsf{\mu }$s rise/336 $\mathsf{\mu }$s fall time, and has a 3 dB bandwidth of 1.4 kHz under zero-bias conditions. The high performance can be attributed to the suitable energy band structure of Bi${}_2$Se${}_3$/ReSe${}_2$ and high carrier mobility in surface states of Bi${}_2$Se${}_3$. Excitingly, self-powered TIs photodetectors allow for high-quality signal transmission. The TIs employed in photodetectors can stimulate the production of new optoelectronic features, but they could also be used for highly integrated photonic circuits in the future. Full article

Adopting mobile robots for high voltage (HV) live-line operations can mitigate personnel casualties and enhance operational efficiency. However, conventional mechanical arms cannot inspect concealed spaces in the power cable tunnel because their joint integrates metallic motors or hydraulic serial-drive mechanisms, which limit the arm’s length and insulation performance. Therefore, this study proposes a 7-degree-of-freedom (7-DOF) bionic mechanical arm with rigid-flexible coupling, mimicking human arm joints (shoulder, elbow, and wrist) designed for HV live-line operations in concealed cable tunnels. The arm employs a tendon-driven mechanism to remotely actuate joints, analogous to human musculoskeletal dynamics, thereby physically isolating conductive components (e.g., motors) from the mechanical arm. The arm’s structure utilizes dielectric materials and insulation-optimized geometries to reduce peak electric field intensity and increase creepage distance, achieving intrinsic self-insulation. Furthermore, the mechanical design addresses challenges posed by concealed spaces (e.g., shield tunnels and multi-circuit cable layouts) through the analysis of joint kinematics, drive mechanisms, and dielectric performance. The workspace of the proposed arm is an oblate ellipsoid with minor and major axes measuring 1.25 m and 1.65 m, respectively, covering the concealed space in the cable tunnel, while the arm’s quality is 4.7 kg. The maximum electric field intensity is 74.3 kV/m under 220 kV operating voltage. The field value is less than the air breakdown threshold. The proposed mechanical arm design significantly improves spatial adaptability, operational efficiency, and reliability in HV live-line inspection, offering theoretical and practical advancements for intelligent maintenance in cable tunnel environments. Full article

This paper presents the first demonstration and comparison of two identical oscillator circuits employing piezoelectric zinc oxide (ZnO) microelectromechanical systems (MEMS) resonators, implemented on conventional printed-circuit-board (PCB) and three-dimensional (3D)-printed acrylonitrile butadiene styrene (ABS) substrates. Both oscillators operate simultaneously at dual frequencies (260 MHz and 437 MHz) without the need for additional circuitry. The MEMS resonators, fabricated on silicon-on-insulator (SOI) wafers, exhibit high-quality factors (Q), ensuring superior phase noise performance. Experimental results indicate that the oscillator packaged using 3D-printed chip-carrier assembly achieves a 2–3 dB improvement in phase noise compared to the PCB-based oscillator, attributed to the ABS substrate’s lower dielectric loss and reduced parasitic effects at radio frequency (RF). Specifically, phase noise values between −84 and −77 dBc/Hz at 1 kHz offset and a noise floor of −163 dBc/Hz at far-from-carrier offset were achieved. Additionally, the 3D-printed ABS-based oscillator delivers notably higher output power (4.575 dBm at 260 MHz and 0.147 dBm at 437 MHz). To facilitate modular characterization, advanced packaging techniques leveraging precise 3D-printed encapsulation with sub-100 μm lateral interconnects were employed. These ensured robust packaging integrity without compromising oscillator performance. Furthermore, a comparison between two transistor technologies—a silicon germanium (SiGe) heterojunction bipolar transistor (HBT) and an enhancement-mode pseudomorphic high-electron-mobility transistor (E-pHEMT)—demonstrated that SiGe HBT transistors provide superior phase noise characteristics at close-to-carrier offset frequencies, with a significant 11 dB improvement observed at 1 kHz offset. These results highlight the promising potential of 3D-printed chip-carrier packaging techniques in high-performance MEMS oscillator applications. Full article

In this work, the indoor thermal environment and indoor air quality of rural houses in Northern China were investigated in detail. The current heating situation in rural areas, the causes of indoor air pollution, and the indoor ventilation habits of residents were analyzed. The indoor thermal environment and indoor air quality were improved by upgrading the thermal insulation of the rural housing envelope and installing indoor ventilation systems with heat recovery, leading to an average indoor temperature increase of 6 °C. The Predicted Mean Vote reached approximately 1.0, so the human body heat sensation was more moderate. The air age was greatly reduced, and the indoor air quality was significantly improved. The Predicted Percentage of Dissatisfied dramatically decreased to 15%. Thus, when focusing on heat source renovation in rural areas, priority should be given to improving the energy efficiency of buildings, especially the building envelope insulation performance. Ventilation and air exchange systems with heat recovery are inexpensive and effective, and they are suitable for rural dwellings where the temperatures are not as high as they should be but where the indoor air quality is poor and ventilation is urgently needed. Full article

In order to rationally utilize wood materials, increase wood quality, and mitigate drawbacks, research on industrial techniques for timber protection and preservation is essential on a European and global scale. When high-quality timber enters the market, it offers structures and objects that have considerable added value. This study examines the performance of thermally treated (6 h at 170 °C and 200 °C) softwood species (fir wood) when exposed outdoors and applied on wooden building structures as cladding timber, among other structures. International standards were applied for the characterization of the untreated and thermally treated wooden boards after the treatments in terms of physical, hygroscopic, and surface properties. In contrast, all the boards (of dimensions 390 × 75 × 20 mm in length, width, thickness respectively) were exposed outdoors to direct sunlight and a combination of biotic and abiotic factors for a six-month period to mainly investigate the thermal properties (heat transfer analysis/insulation properties) using a real-time test in situ, as well as to investigate their potential resistance to natural weathering (color, surface roughness, visual inspection, etc.). Heat transfer in the thermally treated wood specimens was found to be much slower than that in the untreated specimens, which, combined with lower hygroscopicity and higher dimensional stability, reveals the high potential of thermally treated wood utilization in outdoor applications, such as cladding, facades, frames, and other outdoor elements. Full article

In recent years, the building insulation layer peeling caused by quality problems has brought about safety hazards to human life. Existing means of non-destructive testing of building insulation layers, including laser scanning, infrared thermal imaging, ultrasonic testing, acoustic emission, ground-penetrating radar, etc., are unable to simultaneously guarantee the detection depth and resolution of the insulation layer defects, not to mention high-precision imaging of the insulation layer structure. A new type of high-precision imaging radar is specifically designed for the quantitative quality inspection of external building insulation layers in this paper. The center frequency of the radar is 8800 MHz and the −10 dB bandwidth is 3100 MHz, which means it can penetrate the insulated panel not less than 48.4 mm thick and catch the reflected wave from the upper surface of the bonding mortar. When the bonding mortar is 120 mm away from the radar, the radar can achieve a lateral resolution of about 45 mm (capable of distinguishing two parties of bonding mortar with a 45 mm gap). Furthermore, an ultra-wideband high-bunching antenna is designed in this paper combining the lens and the sinusoidal antenna, taking into account the advantages of high directivity and ultra-wideband. Finally, the high-precision imaging of data collected from multiple survey lines can visually reveal the distribution of bonded mortar and the bonding area. This helps determine whether the bonding area meets construction standards and provides data support for evaluating the quality of the insulation layer. Full article

Since epoxy resin has excellent mechanical and insulating qualities, it is frequently utilized in dry transformers. Low thermal conductivity, however, has prevented it from be developed further in high-frequency and large-capacity dry transformers. This study describes the preparation of sheet boron nitride (BN)/epoxy resin composites with superior electrical, thermal, and mechanical properties through the application of varying strengths of high-frequency alternating-current (AC) electric fields. Using an optical microscope, the orienting process of BN in epoxy resin under an electric field was studied. In parallel, tests were conducted on the BN/epoxy resin composites made with varying electric field strengths. The findings indicate that the preparation using a high-frequency AC electric field decreases BN agglomeration and improves the composite’s properties. The overall performance is comparatively ideal when the applied electric field strength is 30 V/mm, the tensile strength is 48.3 MPa, the breakdown field strength is 37.65 kV/mm, and the thermal conductivity of the BN/epoxy resin composite is 0.95 W/(m·K). The thermal conductivity greatly increased and BN was organized into chains when the electric field approached 60 V/mm. The tensile strength and breakdown field strength, on the other hand, declined. Full article

The advancement of portable high-definition organic light-emitting diode (OLED) displays necessitates thin film transistors (TFTs) with low power consumption and high pixel density. Amorphous indium gallium zinc oxide (a-IGZO) TFTs are promising candidates to meet these requirements. However, conventional silicon dioxide gate insulators provide limited channel modulation due to their low dielectric constant, while alternative high-k dielectrics often suffer from high leakage currents and poor surface quality. Plasma-enhanced atomic layer deposition (PEALD) enables the atomic-level control of film thickness, resulting in high-quality films with superior conformality and uniformity. In this work, a systematic investigation was conducted on the properties of HfO₂ films and the electrical characteristics of a-IGZO TFTs with different HfO₂ thicknesses. A Vth of −0.9 V, μ_sat of 6.76 cm²/Vs, SS of 0.084 V/decade, and I_on/I_off of 1.35 × 10⁹ are obtained for IGZO TFTs with 40 nm HfO₂. It is believed that the IGZO TFTs based on a HfO₂ gate insulating layer and prepared by PEALD can improve electrical performance. Full article

Seagrass ecosystems provide essential ecological services and are increasingly recognized for their potential as sustainable building insulation. While prior studies have examined seagrass insulation in temperate climates, its suitability for tropical construction remains largely unexplored. This study assesses the insulation performance, practical challenges, and adoption barriers of seagrass insulation in tropical climates, using building physics simulations and structured expert interviews, with case studies in Seychelles and Auroville, India. Simulation results indicate that seagrass insulation with its high specific heat capacity effectively reduces overheating risks and demonstrates consistently low mould-growth potential under persistently humid tropical conditions. Despite these technical advantages, expert interviews reveal significant non-technical barriers, including negative public perception, regulatory uncertainties, and logistical complexities. Seychelles faces particular hurdles such as limited coastal storage capacity and stringent environmental regulations. In contrast, Auroville emerges as an ideal demonstration site due to its strong sustainability culture and openness to innovative building materials. The study further identifies that integrating seagrass insulation into a structured, regulated supply chain—from sustainable harvesting and processing to quality assurance—could simultaneously enhance ecosystem conservation and material availability. Implementing a harvesting framework analogous to sustainable forestry could ensure environmental protection alongside supply stability. The findings emphasize the urgent need for targeted awareness initiatives, regulatory alignment, and economic feasibility assessments to overcome barriers and enable wider adoption. Overall, this research highlights seagrass insulation as a promising, climate-positive construction material with strong potential under tropical conditions, provided that identified logistical, societal, and regulatory challenges are addressed through dedicated research, stakeholder collaboration, and practical pilot projects. Full article

Tapes are widely utilized across various industries, offering versatile solutions for bonding, sealing, and packaging applications. Their ease of use, strength, and adaptability make them essential in manufacturing, construction, and consumer markets. However, the effectiveness of tapes depends heavily on their adhesive performance, which is influenced by factors such as the adhesive layer composition, material compatibility, environmental conditions, and contact parameters. Quantifying adhesive performance through standardized testing is critical to ensuring reliability, optimizing functionality, and meeting industry-specific requirements. Traditional methods, such as peel and shear tests, are commonly used to evaluate the adhesive and shear strength of tapes. However, these methods typically operate at macro-load scales and often use complex sample geometries and significant material quantities. Recently, precision indentation–retraction testing has emerged as a promising technique for accurately quantifying the adhesion and cohesion forces of viscoelastic fluids. This study adapts this method to evaluate and compare the adhesive strength of various commercially available adhesive tapes. The adhesion force and separation energy of five commercial tapes, namely paper masking tape, high-temperature tape, insulation tape, duct tape, box wrapping tape, and double-sided tape, were measured using a Falex Tackiness Adhesion Analyser (TAA) tester, under controlled conditions (approach speed: 0.01 mm/s, retraction speed: 0.1 mm/s, and load: 50 mN). The results indicated that the adhesion force and separation energy varied significantly among the tapes, whereas a different pattern in the indentation–retraction curves was obtained for these tapes. In addition, the significance of difference among the adhesive properties of the tapes was assessed with the use of analysis of variance (ANOVA). This innovative approach not only enhances the precision of adhesive strength measurements but also provides valuable insights into adhesive layer properties, offering a novel tool for research, development, and quality control in tape production. Full article