Search Results (3,042)

In dense indoor Internet of Things (IoT) environments, simultaneously transmitting and reflecting intelligent surfaces (STAR-IRS) can provide full-space coverage by steering energy to both sides of the surface. However, most STAR-IRS works focus on the physical layer and overlook medium access control (MAC) challenges, such as how to collect channel state information (CSI), dynamically assign each STAR-IRS element to either the reflection or transmission mode, and coordinate concurrent users. We propose a two-stage MAC protocol that couples carrier sense multiple access with collision avoidance (CSMA/CA) for contention and time division multiple access (TDMA) for scheduled data transmission. During contention, devices send extended request-to-send (eRTS) frames to enable CSI acquisition; during transmission, the access point (AP) configures the STAR-IRS, allocates TDMA slots, and pairs one reflection-region device (RD) with one transmission-region device (TD) for non-orthogonal multiple access (NOMA) with successive interference cancellation (SIC). Analysis and simulations show that the proposed scheme increases throughput and reduces delay compared with reflective-only IRS baselines without NOMA, while remaining practical for dynamic indoor IoT. Full article

Polymer infiltration and pyrolysis (PIP) is a versatile route for densifying carbon–carbon composites (C/CCs) and ultra-high-temperature ceramic matrix composites (UHTCMCs), particularly SiC and UHTC-based systems. It operates at comparatively low temperatures, accommodates complex shapes, and is more cost-effective than chemical vapor infiltration (CVI). However, conventional PIP has intrinsic limitations, including low ceramic or char yield, significant shrinkage and gas evolution during pyrolysis, and the need for many infiltration–pyrolysis cycles to reach useful densities. Recent strategies to reduce these drawbacks include graded-concentration and high-pressure PIP, as well as hybrid CVI–PIP and PIP–reactive melt infiltration (RMI) schemes. In parallel, a separate body of work has shown that vacuum-assisted and vibration-assisted infiltration can improve impregnation quality in carbon or ceramic fiber preforms and in carbon-based UHTCMCs. Yet, these advances are rarely synthesized from a PIP-centered, manufacturing-focused perspective or systematically extended to the densification of porous C/C structures, particularly when high-viscosity modified phenolic or particle-laden preceramic precursors are used. This review summarizes the state of the art in PIP densification and processing–structure–property relationships in modified C/CCs or UHTCMCs and related high-temperature composites. It then examines vacuum- and vibration-assisted infiltration concepts, extracts the underlying fluid- and pore-scale mechanisms, and proposes design principles for enhanced PIP equipment and processes tailored to porous and modified C/C systems for space and defense thermal protection. Full article

Organic manure application is considered an effective strategy for enhancing soil fertility and increasing carbon sequestration in saline-sodic soil. The contribution of manure-derived soil organic carbon (SOC) under long-term application remains unclear, as do its concurrent effects on SOC and soil inorganic carbon (SIC) pools. Empirical evidence addressing both aspects is scarce. This study was based on a long-term field experiment established in saline-sodic soil, with four manure application durations (14, 19, 25, and 30 years) and an unfertilized control, each with three replicates. Soil samples were collected from a 0–200 cm profile to investigate the vertical distributions of SOC, permanganate-oxidizable organic carbon (POXC), δ¹³C values, SIC and its carbonate (CO₃²⁻) and bicarbonate (HCO₃⁻) fractions. The effects of manure application on the sources of SOC and the fractions of SIC were investigated using one-way analysis of variance (ANOVA) and the widely applied binary equations. The results revealed that long-term manure application significantly increased the SOC, POXC, SIC, and HCO₃⁻ contents, whereas the CO₃²⁻ content decreased. The effects were most notable within the 0–60 cm soil layer. The δ¹³C values of SOC increased significantly with increasing fertilization duration, which indicates increased incorporation of exogenous carbon. The results of a binary mixing model revealed that after 30 years of manure application, manure-derived carbon contributed 31.64% (7.44 g kg⁻¹) to SOC, maize-derived carbon contributed 22.42% (5.27 g kg⁻¹) to SOC, and the remaining fraction originated from native SOC. Vertically, the SOC content decreased with soil depth, whereas the SIC content fluctuated and became dominant below 60 cm. Long-term manure application altered both SOC sources and SIC dynamics, thereby promoting the accumulation and redistribution of carbon within the soil profile. Overall, long-term manure application increased both organic and inorganic carbon content. These findings highlight the importance of organic fertilization as a sustainable management practice for increasing soil carbon storage and mitigating land degradation in saline-sodic agroecosystems. Full article

Passive-microwave sea ice concentration (SIC) products, such as AMSR2, provide broad coverage but limited spatial detail in coastal and marginal ice zones. This study presents a Sentinel-1 IW-mode dual-polarimetric framework for interannual sea ice characterization in the Southern Sea of Okhotsk. Twenty Sentinel-1 SLC scenes acquired during February–March 2022–2026 were aligned to a common SAR footprint and restricted to an ocean-only domain using a temporal ${\mathsf{\sigma }}_{\mathrm{VV}}^0$-based land/ocean mask. Open water was separated using an incidence-angle-normalized ${\mathsf{\sigma }}_{\mathrm{VV}, \mathrm{norm}}^0$ threshold; the correction was evaluated through leave-one-scene-out analysis, and threshold robustness was assessed through sensitivity testing. The remaining ice-candidate pixels were partitioned into surface-like, mixed, and random/dipole-like scattering regimes in H–α space. Sentinel-1-derived ice fractions were compared with temporally collocated AMSR2 Level-2 SIC. The comparison showed a moderate positive association at the scene-mean level ($R^2$ = 0.277, RMSE = 24.85%, bias = +0.13%) and footprint scale ($R^2$ = 0.429, RMSE = 29.98%, bias = −0.11%). The large RMSE values indicate weak absolute agreement, particularly at the footprint scale. The framework provides higher-resolution information on sea ice coverage and scattering-regime composition, but Sentinel-1-derived ice fraction and AMSR2 SIC should not be interpreted as interchangeable quantities. Full article

This study employs density functional theory and quantum chemical calculations to investigate the gas-phase nucleation and growth mechanisms during chemical vapor deposition of silicon carbide. Based on thermodynamic stability evaluations of large clusters under various configurations, the lowest-energy ground-state structure was determined. The Gibbs free energy (ΔG) calculations of pure silicon clusters (Si_n), single-carbon silicon clusters (Si_nC), and double-carbon silicon clusters (Si_nC₂) were conducted at different temperatures. The findings reveal that silicon atoms promote cluster growth. The special 2D-to-3D configurational transition attenuates the reaction’s spontaneity. During the initial nucleation stage, the system tends to form Si_nC; however, as the size increases, it evolves into the more stable Si_nC₂. This study reveals gas-phase cluster formation at the atomic scale, providing a theoretical foundation for suppressing detrimental gas-phase nucleation. Full article

This study investigated the structure and properties of flame-sprayed composite coatings based on ultra-high molecular weight polyethylene (UHMWPE) modified with Al₂O₃ and SiC ceramic fillers. The results of the composite coatings showed that the filler particles were preserved within the polymer matrix, covered by polymer fibers, and strongly bonded to the matrix. The X-ray diffraction analysis showed that for the samples containing Al₂O₃, the degree of crystallinity decreased from 77% to 64%, while for the SiC-containing samples, it remained in the range of 71–76%. The maximum microhardness was achieved in the coating with 15 wt.% Al₂O₃, reaching 8.15 ± 0.5 HV0.03, which represents a 50.9% increase compared with the initial UHMWPE coating. In the case of the SiC filler, the maximum microhardness was achieved at a content of 20 wt.%, reaching 7.40 ± 0.4 HV0.03. The abrasive wear test results demonstrated that both fillers enhanced the wear resistance of the coatings. The coatings containing 15–20 wt.% SiC exhibited the highest wear resistance, with a mass loss of approximately 0.02 g. In the case of the Al₂O₃ filler, the minimum mass loss was achieved at a content of 20 wt.%, reaching approximately 0.032 g. Full article

This article reviews the reactive magnetron sputtering of piezoelectric Aluminium Nitride (AlN) thin films, with a focus on process parameter optimisation and system-level deposition challenges. AlN is a leading material for MEMS and RF applications owing to its c-axis (002) orientation, high acoustic velocity, wide bandgap (∼6.2 eV), and CMOS compatibility. We review the influence of sputtering power, nitrogen flow ratio, substrate temperature, and target-to-substrate distance on crystallographic quality and document practical hardware challenges, including vacuum leakage, grounding faults, target erosion, and mass flow controller drift, that critically affect reproducibility but are systematically underreported in the literature. A perspective is provided on emerging application domains where optimised AlN films address current performance gaps, including next-generation RF/telecom systems towards 6G and Future Networks, harsh environment sensing and actuation, biomedical ultrasound, and IoT energy harvesting. The complementarity between AlN and Silicon Carbide (SiC) is discussed for high-temperature, high-power, and radiation-hard MEMS, where AlN/SiC heterostructures combine the piezoelectric activity of AlN with the mechanical and chemical robustness of SiC. It also incorporates a discussion of dopant- and heteroepitaxy-based AlN engineering, AlN deposition on a wider range of substrates, the role of seed and electrode underlayers, and pulsed-DC sputtering as a third power supply mode alongside RF and conventional DC. Full article

The electrical drive and the electrical motor share the same housing in Integrated Motor Drives (IMDs), which directly affects the reliability of failure-prone components in such a system. Existing studies are often conducted without considering system-level electrothermal reliability interactions in IMDs. This paper proposes a framework for electrothermal modeling for reliability analysis of IMDs during the early design phase. The framework is based on a back-to-back converter as an emulation platform adaptable to different high-speed electrical machines through software reconfiguration alone. It follows two stages: first, it converts the real-world mission profile, including high-speed operation, into load current commands and motor power loss. Secondly, the thermal network modeling accounts for thermal coupling between the components and the motor, which affects the junction temperature and the hot-spot temperature of the DC link capacitor. The parameters of the thermal network of the electrical motor can be the result of a multiphysics simulation or a real available motor. This framework enables reliability assessment considering motor thermal effects in the early design phase without requiring a physical motor prototype, while providing a fast and cost-effective approach for reliability evaluation. The experimental tests are performed to validate an electrothermal modeling framework capable of thermal modeling and reliability analysis. In addition, the reliability analysis of the power device is carried out by doing the simulation results using data from a real motor, selected for integrated power converter applications. The results demonstrate that the thermal interaction between the motor and the electrical drive causes an $11.5\%$ reduction in the predicted $B_{10}$ lifetime compared with the non-integrated configuration. The non-integrated configuration exhibits approximately 20,000$\mathrm{km}$ longer lifetime than the integrated configuration, highlighting the importance of considering motor-drive thermal coupling in IMD reliability assessment. Full article

Silicon carbide (SiC) in its various structural modifications is widely used in power semiconductor electronics, operating under extreme conditions of high temperature, high voltage, and intense radiation. The discovery of spin defects (S > 0) with unique optical and coherent properties has further positioned SiC as a promising platform for quantum technologies. Here, we investigate a 6H-SiC single crystal co-doped with nitrogen and beryllium at concentrations of 10¹⁸ cm⁻³, using continuous-wave and pulsed electron paramagnetic resonance (EPR) and electron–nuclear double resonance (ENDOR). To enhance spectral resolution, experiments were conducted in the W-band (94 GHz; B = 3.4 T). Pulsed EPR identified nitrogen donors and beryllium acceptors in various lattice positions, allowing for the determination of their phase coherence and spin–lattice relaxation times. ENDOR measurements elucidated the electron–nuclear interactions with the local silicon and carbon environment, including distant coordination spheres. The observed hyperfine structures indicated highly delocalized spin density within the supercell. The TRIPLE resonance spectra verify coupled nuclear spin subspaces from different coordination spheres due to defect spin density. These results demonstrate the feasibility of incorporating dual impurities with distinct functional roles while preserving the crystal lattice’s structural features. Full article

Remaining useful life (RUL) prediction of power semiconductor devices plays a crucial role in reliability design and predictive maintenance of power control system. This article introduces a data-driven methodology on predicting the RUL of the gate oxide layer in silicon carbide (SiC) MOSFETs. Firstly, a power cycling platform is established to collect the time-varying curves of threshold voltage and construct an aging dataset. Then, the successive variational mode decomposition (SVMD) algorithm is employed to adaptively decompose the signal of gate threshold voltage, helping suppress measurement noise and fluctuations caused by operating conditions while retaining degradation features. Subsequently, a Temporal Convolutional Network (TCN) is adopted to capture temporal dependencies in the degradation sequence, thereby improving the characterization of gate oxide health status assessment. Finally, the extended Kalman particle filter (EKPF) is employed to estimate the degradation state and quantify the associated uncertainty by recursively fusing model predictions with real-time measurements. The proposed method integrates the adaptive signal decomposition capability of SVMD, the temporal feature extraction capability of TCN, and the uncertainty quantification capability of EKPF. Their complementary integration improves prediction accuracy and robustness in gate oxide degradation evaluation for SiC MOSFET. Full article

Single-event burnout (SEB) remains a persistent threat to SiC power MOSFETs in space, yet rapid evaluation of SEB susceptibility without costly heavy-ion campaigns is challenging. This work demonstrates that femtosecond laser two-photon absorption (TPA) can fill that role for a commercial 1200 V SiC MOSFET—provided the laser energy is correctly mapped to heavy-ion linear energy transfer (LET). We derive an equivalent LET model that incorporates the thermal spike effect, giving LET_eq = Γ₁E₀² + Γ₂E₀⁴, which corrects the classical square law at high excitation intensities where it fails. Three ionization-driven failure signatures emerge: drain-to-gate and drain-to-source single-event leakage current (SELC), and SEB. The SEB threshold saturates near 500 V once LET exceeds 25 MeV·cm²/mg—roughly 42% of the device’s 1200 V rating. From these thresholds, we define a safe operating area: below 200 V is safe, 200–600 V risks SELC degradation, and above 600 V carries high SEB risk. Benchmarking against published heavy-ion data shows SEB threshold agreement within 15%, and within 5% at high LET. We stress that the TPA method captures ionization-driven effects only; it does not replicate displacement damage. These results support rapid, laser-based screening of SiC power devices for radiation hardness. Full article

This paper studies the encounter between Jesus and the Samaritan woman in John 4:1–42 through the lens of Social Identity Complexity (SIC) theory, focusing on its implications for ethno-religious solidarity, conflict resolution and peacebuilding in Northern Nigeria. The study explores how Jesus navigates complex social identities by crossing geographical, ethno-religious, and gender boundaries, presenting a model of inclusive and boundary-crossing social identity. Through this interdisciplinary approach, the paper argues that Jesus’ ability to affirm and integrate non-convergent social identities under a superordinate identity provides a framework for promoting ethno-religious tolerance, reconciliation, and peaceful coexistence. The analysis highlights the relevance of this model for addressing the ongoing ethno-religious conflicts in Northern Nigeria, where geographical and ethno-religious divisions persist. By drawing parallels between the Samaritan-Jewish conflict and the Christian-Muslim tensions in Northern Nigeria, the paper demonstrates the potential of SIC as a tool for fostering dialogue, reducing stereotypes, and building inclusive social identities that contribute to long-lasting peace. Full article

During the preparation of silicon carbide (SiC) thin films by chemical vapor deposition (CVD), the Soret effect induced by a large temperature gradient influences the deposition rate and uniformity; its sensitivity to process parameters remains unclear. A computational fluid dynamics model coupling detailed gas-phase and surface reaction kinetics was developed and validated for a cold/warm wall vertical CVD reactor. Comparing simulations with and without the thermal diffusion term reveals the dual role—suppressing deposition rate while degrading film uniformity. The thermal diffusion contributions to deposition rate (TDC_GR) and uniformity (TDC_GU) are introduced as quantitative metrics, and simulations evaluated the effects of inlet–substrate temperature difference (ΔT), reactor pressure (p), substrate rotation speed (ω), and carrier gas flow rate (Q) on the Soret effect, clarifying optimal conditions. Results show ΔT dominates. At ΔT = 1700 K, TDC_GR = −56.39% and TDC_GU = 5.29%. Pressure affected TDC_GR negligibly but significantly reduced TDC_GU by enhancing gas-phase mixing; increasing p from 7500 to 12,500 Pa led to a decrease in TDC_GU from 4.19% to 1.93%. Optimal parameters (ΔT = 1400 K, p = 12,500 Pa, ω = 800 rpm, Q = 50 slm) achieved a deposition rate of 10.71 μm/h and non-uniformity of 0.45%. These findings provide theoretical guidance for precise SiC-CVD process control in cold- or hot-wall vertical reactor architectures. Full article

A cascade impactor equipped with microparticle surface acoustic wave sensors along with a surface cleaning system is an innovative system developed by our team to measure particles and monitor air quality. The system has been proven to function properly under various particle concentrations. Nevertheless, long exposure times and heavily polluted media impose a limitation on cascade impactors, known as surface saturation. This problem affects the sensitivity of our sensors, which tends to degrade with particles fouling the surface. To overcome this issue, a surface cleaning system that uses a Rayleigh wave-actuated water droplet has been implemented and tested. Rayleigh waves were generated on an innovative SAW chip, thus exciting the droplet using Radio-Frequency power. NaCl solutions and SiC particles were considered. The optimal droplet size was determined along with the required Radio-Frequency power. Experiments showed that the SAW-driven droplet successfully displaced the collected particles outside of the sensing zone, irrespective of their nature, without affecting the sensor’s performance. The results found in this study provide further improvements to our particle measuring system, advancing it towards an autonomous self-regenerating prototype. Full article

Large-scale high-value utilization of industrial solid waste is urgently required worldwide. Porous ceramics prepared from single-type solid waste face great limitations in balancing mechanical properties and thermal insulation performance. In this work, various types of industrial solid wastes—red mud, waste electric porcelain, and coal gangue—were fully adopted as primary raw materials, while SiC was employed as a foaming agent to prepare porous ceramics. Results show that at 3% SiC addition and 1140 °C sintering temperature, the apparent porosity of the ceramics reaches to 21.8%, with thermal conductivity of 0.08 W/(m·K). Moreover, favorable pore-size distribution and desirable crystalline phases (Mg–Fe–Al spinel and sodium calcium feldspar) are obtained under this optimal condition, accompanied by a favorable compressive strength of 2.91 MPa, making it a promising low-cost, high-performance high-temperature insulation material. Full article