Search Results (1,366)

Background: China’s influenza vaccine (InfV) has undergone multiple iterations and numerous technological breakthroughs, providing tremendous impetus and solid support for the development of China’s health sector. As the number of vaccinated individuals continues to rise, the importance of ongoing surveillance and evaluation of vaccine safety has become increasingly prominent, forming part of efforts to maintain public trust in the national immunization program and ensure its sustainability. Methods: From 2016 to 2025, data on suspected adverse events following immunization (AEFIs) related to InfV administration were extracted from the Chinese National Immunization Information System (CNIIS). Data on InfV vaccination doses were obtained from the Anhui Provincial Immunization Information Management System. A descriptive statistical method was used to analyze the distribution characteristics of AEFIs, and the chi-square test was applied to evaluate differences in reporting rates. Results: Between 2016 and 2025, a total of 4026 AEFI reports related to InfV were monitored through the CNIIS. The overall reporting rate was 34.40 per 100,000 doses. Specifically, common adverse reactions and rare adverse reactions accounted for 95.88% (3860 cases) and 3.38% (136 cases), with reporting rates of 32.98 per 100,000 doses and 1.16 per 100,000 doses, respectively. Among common adverse reactions, the reporting rates of fever (axillary temperature ≥ 38.6 °C), local redness and swelling at the injection site (diameter > 5.0 cm), and local induration (diameter > 5.0 cm) were 9.62 per 100,000 doses, 1.96 per 100,000 doses, and 1.20 per 100,000 doses, respectively. Among rare adverse reactions, the reporting rates of allergic rash, angioedema, anaphylactic shock, febrile convulsions, anaphylactoid purpura, thrombocytopenic purpura, epilepsy, Guillain–Barré syndrome, and aseptic abscess were 0.98, 0.05, 0.03, 0.03, 0.02, 0.02, 0.01, 0.01, and 0.01 per 100,000 doses, respectively. No cases were reported for subunit inactivated influenza vaccine (IIV, Subunit). Statistically significant differences were observed in the reporting rates of allergic rash across different types of InfV (χ² = 36.83, p < 0.05), with trivalent inactivated influenza vaccine (IIV3, Split) and trivalent live attenuated influenza virus vaccine (LAIV3) showing the highest reporting rates. Most adverse events following vaccination occurred within 24 h after inoculation. Conclusions: From 2016 to 2025, the overall reporting rate of AEFIs after InfV administration in Anhui Province was within an acceptable range. Common adverse reactions were common, while rare adverse reactions were few, mainly consisting of allergic reactions. These results indicate that InfV has a favorable safety profile, and continuous strengthening of AEFI surveillance for InfV and improvement of surveillance quality are warranted. Full article

Surge reliability is a crucial aspect of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) reliability. This study investigates the degradation behavior and mechanisms of switching characteristics in 1.2 kV planar-gate SiC MOSFETs under repetitive surge current. A surge current test platform is established to conduct surge tests on the device, while monitoring the evolution of its switching characteristics. The results indicate that after 4000 surge current cycles, the device’s turn-on delay time (t_d(on)), rise time (t_r), and turn-on loss (E_ON) show no significant changes. In contrast, the turn-off delay time (t_d(off)), fall time (t_f), and turn-off loss (E_OFF) increase by 9%, 7.5%, and 8.3%, respectively. Switching characteristics variations are closely linked to the reduction in threshold voltage (V_TH) and the increase in gate-source capacitance (C_GS) and gate-drain capacitance (C_GD). The degradation of these parameters stems from the accumulation of positive trapped charge in the gate oxide layer above the channel and junction field-effect transistor (JFET) region. The increase in charges results from the combined effects of negative gate bias and cyclic high temperature induced by repetitive surge current. This study provides a theoretical basis for the comprehensive understanding of the impact of surge current on SiC MOSFET performance. Full article

To reveal the electromagnetic response characteristics and hydro-thermal evolution mechanism of frozen soil under microwave irradiation, we used remolded frozen soil prepared from undisturbed parent soil collected in Hegang, China, as the research object. We conducted dielectric parameter tests across the 715–1150 MHz and 2250–2650 MHz frequency bands and 1.5 kW microwave heating tests on specimens with three gravimetric water contents (15%, 20%, and 25%) paired with a coupled numerical simulation of electromagnetic field-heat transfer-moisture migration. The results show that water content is the dominant factor controlling the dielectric response of frozen soil. The dielectric loss and water content sensitivity of frozen soil in the low-frequency band (dominated by unfrozen water) are significantly higher than those in the high-frequency band (dominated by ice phase and soil matrix). Microwave-induced temperature rise exhibits a three-stage characteristic, as follows: slow temperature rise, isothermal plateau at the freezing point, and rapid temperature rise. Specimens with a lower initial water content show a higher temperature rise efficiency in the late heating stage, with a maximum rate of 1.112 °C·s⁻¹ for the 15% water content specimen. Mass loss is negatively correlated with initial water content, with a maximum value of 1.8 g after 120 s of irradiation. In addition, the non-uniformity of the electromagnetic field results in a temperature field pattern characterized by a high-temperature core at the specimen center and lower temperatures at the edges. This study provides fundamental theoretical support and technical guidance for the application of microwave thawing technology in geotechnical engineering, particularly for frozen soil foundation treatment in cold regions. Full article

Fire protection remains one of the key challenges in the field of architectural heritage conservation, particularly for heritage buildings dominated by timber structures, which face greater difficulties in fire prevention and risk assessment. To systematically evaluate the fire safety performance of high-rise timber heritage buildings, this study takes the Shengjin Pagoda, a typical brick–timber pavilion-style ancient tower in Jiangxi Province, China, as the research object. A three-dimensional performance-based fire assessment framework was developed using Fire Dynamics Simulator (FDS) and PyroSim. Based on field survey data and historical documentation, the geometric characteristics, material properties, and vertical circulation system of the pagoda were reconstructed. Three representative fire scenarios, including bottom-floor ignition, simultaneous multi-level ignition, and wind-driven top-floor ignition, were established to investigate smoke propagation, thermal insulation degradation, and the thermal response of critical timber components under different fire conditions. The results show that brick walls provide effective thermal insulation during the early stages of fire, with efficiency exceeding 90%, but this decreases to approximately 55% in upper regions due to chimney-effect-driven smoke accumulation. Under wind-driven top-floor ignition, exposed dougong components can reach temperatures of 782 °C, resulting in a progressive “top-down and outside-in” failure mechanism. The study reveals the dominant smoke-driven heat transfer pathways and the failure sequence of critical load-bearing elements. Based on these findings, a performance-based fire protection strategy incorporating vertical virtual smoke control zoning and fire-resistance enhancement of key structural components is proposed to support the sustainable conservation of historic high-rise timber structures. Full article

Bandpass filters based on through-silicon-via (TSV) interposers offer advantages such as compact footprint, excellent radio frequency (RF) performance, simplified processing, and low cost. However, as power densities in three-dimensional (3D) integrated circuits continue to rise, thermal management has become a critical performance bottleneck. In this work, we present a TSV-based bandpass filter design where the TSVs feature annular Cu conductors with carbon nanotube (CNT) cores. The annular Cu structure provides the required vertical electrical connectivity, while the high-thermal-conductivity CNT core facilitates inter-layer heat dissipation. RF simulations confirm that the RF characteristics of the filter remain comparable to those of filters based on conventional TSVs with Cu-pillar conductors or TSVs with annular Cu conductors and polymer cores such as benzocyclobutene (BCB). In addition, multiphysics simulations demonstrate that the proposed filter exhibits a maximum steady-state temperature of only 89.1 °C with a 5 W constant heat source attached to the interposer surface and a heat sink at the bottom side, presenting an efficient reduction compared to the other two types. The filter also shows reduced thermally induced surface deformation, confirming the thermal benefits of the CNT cores. Furthermore, comprehensive parametric analyses involving the influences of critical TSV structural parameters on the TSV-based capacitors and inductors are performed, providing guidelines for customized filter design. We believe the proposed design highlights a promising pathway for addressing the thermal management challenges in high-density RF integrated microsystems. Full article

To address missed detections, false alarms, and deployment limitations in thermal defect detection of photovoltaic modules from unmanned aerial vehicle (UAV) infrared images, this paper proposes an improved detection method based on You Only Look Once version 8 nano (YOLOv8n). The proposed method is optimized according to the characteristics of UAV infrared photovoltaic inspection, including small thermal targets, weak and diffuse thermal responses, complex backgrounds, and lightweight deployment requirements. Specifically, a P2 shallow feature layer is introduced to enhance fine-grained feature perception for small thermal defects, while Ghost Convolution (GhostConv) is incorporated into the backbone to reduce model complexity. In addition, C2f-Large Separable Kernel Attention (C2f-LSKA) is embedded in the neck to strengthen contextual and spatial feature modeling under complex infrared backgrounds, and Wise-IoU version 3 (WIoUv3) is adopted to improve bounding box regression and localization stability for boundary-ambiguous thermal anomalies. Experiments are conducted on a self-constructed UAV infrared thermal imaging dataset. From nearly 10,000 inspection images, 3000 representative images are selected and manually annotated, covering typical challenges such as small hot spots, low-contrast defects, complex background interference, and diffuse abnormal temperature-rise regions. Compared with the baseline YOLOv8n, the proposed method improves Precision, Recall, mean average precision at an IoU threshold of 0.5 (mAP@0.5), and mean average precision averaged over IoU thresholds from 0.5 to 0.95 (mAP@0.5:0.95) by 5.1, 11.4, 9.6, and 13.2 percentage points, respectively, while reducing the number of parameters and model size by 65.8% and 61.9%, respectively. These results indicate that the proposed method improves detection accuracy and localization quality under the evaluated UAV infrared inspection setting while maintaining lightweight characteristics. Full article

To investigate the posture control of super-long-span heavy steel box girders during synchronous lifting, this study takes the integral lifting project of the 82 m-span steel box girder of Xiaotun Bridge on the Fuyi Expressway as a case study. A fluid–solid–thermal three-field coupled numerical model was established using Midas NFX 2024 R1 (a general-purpose finite element analysis software for multi-physics and fluid–structure interaction simulations) to explore the alignment and end-displacement characteristics of the steel box girder throughout the lifting process. The results show that under combined thermal and wind loads, girder deflection presents a daily cyclic pattern: temperature rise induces upward arching, while wind-induced vibration generates a mid-span instantaneous amplitude of ±25.0 mm, with a maximum coupled deflection of 31.78 mm. Girder end-displacement increases significantly at lifting heights of 5–25 m and peaks at 25 m. With further height increase and shortened sling length, sway frequency rises while maximum displacement gradually declines. When the plane tilt ratio exceeds 0.17% or the overall unbalanced displacement at lifting points exceeds 12 mm, local stress exceeds 95% of the allowable value, implying potential instability risks. For construction safety, a synchronous intelligent hydraulic lifting system based on the “displacement synchronization and load balancing” strategy was applied. Supported by real-time sensor feedback and adjustment, the system achieves millimeter-level lifting precision and welding positioning accuracy. This study provides a reference for similar synchronous lifting practices of large-span steel box girders. Full article

During heavy oil development, the gathering and transportation of low-temperature wellhead-produced fluids are often accompanied by high viscosity, pipe-wall deposition, and high flow resistance, threatening the continuous and stable operation of gathering systems. Existing studies on wellhead heating mainly focus on overall steady-state heating performance, while variable-flow heat transfer and start–stop control in local heating systems remain insufficiently explored. This study aims to evaluate the steady-state heating capacity, transient thermal response, and start–stop control performance of a localized electric heating section under variable-flow conditions. A 3D fluid–solid-coupled heat-transfer model of the heating element, pipe wall, and internal fluid was developed using COMSOL Multiphysics. The steady-state temperature field, transient heating and cooling behavior, and start–stop control characteristics were analyzed under different flow rates. The results show that, at a heating power of 15 kW and a flow rate of 20 m³/d, the maximum outer-wall temperature reached 564 K, and the average outlet fluid temperature reached 308.83 K, indicating effective heating performance. As the flow rate increased from 10 m³/d to 30 m³/d, the maximum pipe-wall temperature and fluid temperature rise both decreased, whereas the average fluid-side heat-transfer coefficient increased from approximately 700 W/(m²·K) to 1800 W/(m²·K), demonstrating enhanced convective heat transfer. Under a dual-threshold control strategy of 463.15–483.15 K, the system maintained the target temperature near 473.15 K under all tested conditions, while the load factor increased from 37.83% to 86.15%. These findings provide theoretical references and engineering support for optimizing power configuration and improving temperature control strategies in local heating systems for wellhead-produced fluids. Full article

The conventional production of waterborne polyurethane (WPU) typically relies on organic solvents to regulate viscosity; additionally, traditional ionic WPU systems still utilize volatile neutralizers, raising environmental and health concerns. To overcome these limitations and reduce dependence on petrochemical resources, this study presents a solvent-free approach for WPU synthesis using isophorone diisocyanate (IPDI), polytetrahydrofuran (PTMG), and the nonionic PEG derivative Ymer^TM A-130. In addition, castor oil (CO), a renewable and hydroxyl-rich bio-based material, was incorporated as a partial substitute for PTMG to improve both sustainability and material performance. The effects of varying substitution ratios of castor oil on the physical properties of the resulting dispersions, dried films, and coatings were initially investigated. The results indicate that increasing the castor oil content from 0 wt% to 11.8 wt% led to an enhancement in tensile strength, rising from 1.45 MPa to 2.40 MPa. Concurrently, the temperature at 5% weight loss (Td_5%) shifted upward from 263.84 °C to 285.36 °C, indicating a favorable trend in thermal stability. Furthermore, the preliminary solvent resistance, surface wetting characteristics, and environmental durability of the prepared coatings were evaluated and discussed. Full article

To address the critical challenge of excessive junction temperature caused by ultra-high heat flux densities (>100 W/cm²) in deep-sea LED Fish-Attracting Lamp (FAL) arrays, this study proposes a hybrid thermal management scheme integrating interfacial micro-texturing, chimney-effect convection, and heat pipe phase-change heat transfer, achieving the unification of passive high-efficiency heat dissipation and pressure-resistant sealing. The FAL housing structure is reconfigured using topology optimization to construct chimney-effect enhanced flow channels integrated with heat pipe bundle arrays, thereby establishing efficient heat conduction pathways from the Phenolic Resin Substrate (PRS) to the structural periphery. Micro-Element Texture (MET) arrays are fabricated at the PRS thermal interface to enhance interfacial thermal conductance. Based on multi-physics coupled numerical simulation, a parametric mapping model correlating geometric topology with thermal performance is established through response interface methodology, enabling the parametric optimization of micro-texture configurations. A thermal interface performance testing platform is constructed to validate the accuracy and reliability of the numerical model. Experimental results demonstrate that the integrated heat pipe technology effectively suppresses LED junction temperature rise; moreover, groove-type MET arrays oriented perpendicular to the gravity direction not only significantly increase the effective heat dissipation area but also optimize the dynamic characteristics of natural convection. This proposed solution reduces the maximum operating temperature of deep-sea FALs by 6.70% compared with conventional structures, providing an effective engineering solution for thermal structural design of high-power illumination systems. Full article

Coastal wetlands, as sensitive ecological interfaces of land–sea interactions, provide regulating functions and ecosystem service values for maintaining regional ecological security. To achieve systematic restoration of ecological functions and intelligent management of resources in coastal wetlands, it is critical to deconstruct the evolution patterns of their landscape configurations across multiple spatiotemporal scales and precisely identify driving factors and ecological risk transmission mechanisms. This study constructs a trinity framework of “pattern evolution-driver analysis-risk assessment” for landscape ecological risk (LER) evaluation, integrating spatial statistical analyses (Standard Deviational Ellipse, Land Use Transition Matrix) and Geographically Weighted Regression (GWR) models to systematically analyze the spatiotemporal evolution characteristics and multidimensional driving mechanisms of landscape patterns in the Yellow River Delta (YRD), a typical coastal wetland, from 2000 to 2023. The results are as follows: (1) total wetland area initially declines followed by partial recovery, with natural wetlands decreasing persistently and artificial wetlands expanding; (2) Gross domestic product (GDP) and temperature (TMP) are identified as the primary drivers of wetland evolution; (3) Wetland LER levels significantly increase from 2015 to 2020, with the proportion of high-risk areas rising from 10% in 2015 to 23% in 2020; (4) LER is predominantly characterized by High-High (H-H) clustering, with Moran’s I values ranging from 0.493 to 0.672 (all p < 0.001), indicating significant positive spatial autocorrelation. The wetland LER assessment framework developed in this study, grounded in a land–sea integrated perspective, provides decision-making support and theoretical foundations for formulating differentiated wetland restoration strategies and optimizing coastal ecological security patterns. Full article

Rockburst is one of the major geological hazards in the construction of deep-buried and high-geotemperature tunnels. Using triaxial compression tests and acoustic emission (AE) techniques, this paper conducts a preliminary exploratory investigation on the deformation and failure characteristics, mechanical parameters, acoustic emission responses and energy evolution laws of typical rockburst-prone rocks under confining pressures of 10–30 MPa and temperatures of 100–250 °C. The results show that within the research scope, sandstone exhibits brittle characteristics including compaction, linear elasticity, crack initiation and propagation, stable crack propagation stage, accelerated crack propagation stage, and stress drop stage. Within a certain range, peak strength and damage strength increase with the rise in confining pressure and temperature. The elastic modulus increases with rising confining pressure. The damage point may be the critical point of energy conversion and acoustic emission activity. After damage, the work done by external forces is mainly converted into dissipated energy. With the intensification of surrounding rock damage, the ratio of elastic strain energy to total energy gradually decreases, while the ratio of dissipated energy to total energy gradually increases. Acoustic emission activity increases significantly at the damage point and reaches its peak at the peak strength. The cumulative acoustic emission ring count and cumulative energy increase slowly before the peak and grow rapidly after the peak. Under thermo-mechanical action, new cracks in sandstone preferentially initiate along grain boundaries, and the inconsistent deformation between grains will promote the formation of transgranular cracks. The connection, convergence and final penetration of cracks lead to sample failure. The elevation of temperature and confining pressure can enhance the bearing capacity of sandstone, indicating that a high-temperature and high-stress environment may be conducive to the occurrence of rockbursts. The research results provide scientific support for an in-depth understanding of the mechanical behavior and instability risk of rockburst in deep-buried and high-geotemperature tunnels, and can provide a theoretical basis for rockburst prevention and control of high-geotemperature tunnels of the CZ Railway. Full article

To elucidate the corrosion behavior of Ti-based metallic glass composites in chloride-containing environments, this study investigates the corrosion resistance of an in situ dendritic Ti₄₈Zr₂₀Nb₁₂Cu₅Be₁₅ metallic glass composite across varying NaCl concentrations and temperatures. The microstructure, surface film composition, and corrosion characteristics were characterized using XRD, SEM, TEM, EDS, XPS, and electrochemical measurements. Results indicate that the alloy consists of a β-Ti(Zr, Nb) dendritic phase embedded in an amorphous matrix. Both increasing NaCl concentration and rising temperature lead to an increase in corrosion current density and a reduction in the capacitive loop radius, signaling a decline in corrosion resistance. The degradation is primarily characterized by localized corrosion and the selective dissolution of the amorphous matrix, which leaves the dendritic phase increasingly prominent. Following polarization, a multi-component oxide film, dominated by TiO₂, ZrO₂, and Nb₂O₅, develops as a protective layer on the alloy surface. However, higher Cl⁻ concentrations and temperatures destabilize this passive film, accelerating matrix dissolution and compromising the material’s overall protective performance. Full article

Traditional coal mining methods have led to prominent issues of coal resource waste and large-scale solid waste emissions. The integrated “excavation–backfilling–retention” mining technology for inter-section coal pillars and gate roads is one of the key technologies to solve these problems. However, the excavation and mining process associated with this technology imposes higher requirements on the ventilation system. Aiming at addressing the ventilation challenges existing during the implementation of the “excavation–backfilling–retention” method, research on ventilation safety assurance technology for inter-section coal pillars was carried out. Using COMSOL5.5 software, a full-stage ventilation system design model was constructed, adopting a ventilation mode that combines full-air-pressure ventilation with auxiliary local ventilation. The dynamic variation characteristics of the ventilation system under the “excavation–backfilling–retention” method and its capability to prevent and control the risks of O₂ and CO gas accumulation and coal spontaneous combustion were studied. The results show that during the bypass excavation period, the air supply from the auxiliary fan is sufficient, and during the excavation period for the two gate roads, due to the increased ventilation distance, insufficient airflow occurs near the heading face, accompanied by temperature rise, O₂ concentration decrease, and local CO accumulation, posing risks of coal spontaneous combustion and toxic gas accumulation. During the inter-section coal pillar excavation period and the cyclic operation period, after the full-air-pressure ventilation system is established, the airflow becomes stable, ventilation resistance decreases, and both temperature and gas concentrations are controlled within safe limits. However, in the corner areas, auxiliary local ventilation measures are still required due to insufficient O₂ and CO accumulation. The study verifies the feasibility and safety of the integrated “excavation–backfilling–retention” ventilation system, providing a safe ventilation approach for the integrated mining method and supporting the green mining of coal mines and the synergistic development of coal-based solid waste resource utilization. Full article

Interior permanent magnet synchronous motor (IPMSM) has advantages with high power density, wide speed range, small size, and high efficiency, and is widely used in the drive system of electric vehicles. Compared to other types of motors, permanent magnet synchronous motors (PMSMs) have some irreplaceable advantages, but there are also some disadvantages. As a type of PMSM, IPMSMs have problems with large fluctuations in permanent magnet (PM) magnetic field and demagnetization. At present, irreversible demagnetization of PMs is the most serious problem faced by IPMSMs. Once irreversible demagnetization of PMs occurs, it can cause a decrease in the performance of IPMSMs and can even damage the entire drive system. This paper takes an IPMSM with 48 slots, 8 poles, and 66 kW as the research object. Based on the reasons for PM demagnetization, a PM demagnetization model is established to obtain the demagnetization law of PMs. Firstly, the magnetic properties of PM materials were described based on their characteristic curves. The demagnetization mechanism of PMs was analyzed, and the demagnetization process of PMs was studied in combination with the reasons for demagnetization. Secondly, the basic parameters and torque performance of IPMSMs were calculated and analyzed. We analyzed the demagnetization curves of PM materials at different temperatures, calculated the operating points of PMs under various working conditions, and analyzed whether PMs undergo irreversible demagnetization based on the relationship between the operating points of PMs and the knee points of demagnetization curves. A high-fidelity electromagnetic–thermal coupling simulation model has been established, combined with the characteristics of electric vehicle driving conditions, to accurately characterize the temperature rise distribution and electromagnetic parameter changes of IPMSMs under different operating conditions and achieve multi-physics field collaborative analysis. Finally, a finite element model is adopted to simulate uniform and local demagnetization of PMs, and the changing characteristics of motor performance parameters under demagnetization are summarized. Different magnitudes of d-axis reverse current are applied as demagnetization excitation to analyze PM behaviors under various demagnetization degrees. The variations in magnetic flux density, output torque, and no-load back electromotive force (EMF) before and after demagnetization are simulated and analyzed. For the investigated motor and specific magnet grade, this work summarizes the irreversible demagnetization characteristics and corresponding practical judgment references. Full article