Railway Engineering Science (铁道工程科学)•2026•DOI: 10.1007/s40534-025-00381-9
Turnout irregularity governs the stochastic vibration response of vehicle–turnout coupling systems, yet frequency-domain models that preserve the statistical characteristics of each frequency point remain scarce. This study establishes a turnout irregularity full information expression model (TIFIEM) using stochastic harmonic functions (SHF) and applies it to vehicle–turnout stochastic vibration and reliability analysis. Spectral estimation trials identify the Hamming window with a 4096-point window length as optimal for turnout irregularity power spectral density (PSD) estimation, and a fifth-order polynomial is recommended for PSD fitting with minimal error. The TIFIEM reproduces randomness in amplitude, frequency, and phase; a sample size of 250 irregularity realizations minimizes the root-mean-square error against the target spectrum. PSD amplitudes at distinct frequency points follow a Chi-square distribution with 2 degrees of freedom. Application to a No. 18 turnout at 300 km/h identifies the straight switch rail 3–7 m from the switch rail tip and the point rail 53–54 m from the tip as the most wear-susceptible regions. The reliability of the vehicle–turnout structure at the crossing panel decreases to 95.8%, indicating that these zones warrant prioritized inspection.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-025-01766-5
Hygroscopic hydrogel is a promising evaporative-cooling material for high-power passive daytime cooling with water self-regeneration. However, undesired solar and environmental heating makes it a challenge to maintain sub-ambient daytime cooling. While different strategies have been developed to mitigate heat gains, they inevitably sacrifice the evaporation and water regeneration due to highly coupled thermal and vapor transport. Here, an anisotropic synergistically performed insulation-radiation-evaporation (ASPIRE) cooler is developed by leveraging a dual-alignment structure both internal and external to the hydrogel for coordinated thermal and water transport. The ASPIRE cooler achieves an impressive average sub-ambient cooling temperature of ~8.2 °C and a remarkable peak cooling power of 311 W m−2 under direct sunlight. Further examining the cooling mechanism reveals that the ASPIRE cooler reduces the solar and environmental heat gains without comprising the evaporation. Moreover, self-sustained multi-day cooling is possible with water self-regeneration at night under both clear and cloudy days. The synergistic design provides new insights toward high-power, sustainable, and all-weather passive cooling applications.
Journal of Semiconductors (半导体学报 - 中国科学院半导体研究所)•2025•DOI: 10.1088/1674-4926/25010005
A 4H-SiC superjunction (SJ) MOSFET (SJMOS) with integrated high-K gate dielectric and split gate (HKSG-SJMOS) is proposed in this paper. The key features of HKSG-SJMOS involve the utilization of high-K (HK) dielectric as the gate dielectric, which surrounds the source-connected split gate (SG) and metal gate. The high-K gate dielectric optimizes the electric field distribution within the drift region, creating a low-resistance conductive channel. This enhancement leads to an increase in the breakdown voltage (BV) and a reduction in the specific on resistance (Ron,sp). The introduction of split gate surrounded by high-K dielectric reduces the gate−drain capacitance (Cgd) and gate−drain charge (Qgd), which improves the switching characteristics. The simulation results indicate that compared to conventional 4H-SiC SJMOS, the HKSG-SJMOS exhibits a 110.5% enhancement in figure of merit (FOM, FOM = BV2/Ron,sp), a 93.6% reduction in the high frequency figure of merit (HFFOM) of Ron,sp·Cgd, and reductions in turn-on loss (Eon) and turn-off loss (Eoff) by 38.3% and 31.6%, respectively. Furthermore, the reverse recovery characteristics of HKSG-SJMOS has also discussed, revealing superior performance compared to conventional 4H-SiC SJMOS.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.09.001
Understanding the complex flow behavior along a rough rock fracture under high-temperature, high-stress, and high-seepage pressure (HTHM) coupling conditions is of great significance for optimizing deep resource extraction. This study investigates the complex flow behavior of a single rock fracture under coupled HTHM conditions using a self-developed multi-field coupling experimental system, considering real-time high temperatures (20–90 °C), confining pressures (30–120 MPa), and seepage pressures (5–60 MPa). Experimental results show that as confining pressure increases, two typical nonlinear flow behaviors are observed, which are Forchheimer flow and low-velocity nonlinear flow. The increase in temperature and decrease in roughness significantly promote the fluid flow and enhance the nonlinear relationship between the volumetric flow rate and the hydraulic gradient at lower confining pressures (30 MPa). However, the change in temperature and fracture surface roughness does not affect the nonlinear type of fluid flow. Under a given hydraulic gradient, the influence of temperature and fracture roughness on the volumetric flow rate varies with changes in confining pressure. Additionally, this study considers both the viscous and inertial terms, and a modified Forchheimer equation is proposed using two parameters: the contact area ratio and the thermal expansion coefficient of the rock. The proposed model can effectively predict the nonlinear flow behavior of fluid along rough fractured rocks under varying temperatures and surface roughness. The experimental results and the proposed model provide valuable data and theoretical guidance for deep oil and gas exploration as well as hydraulic fracturing design.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-024-2963-z
The microstructural evolution of a cold-rolled and intercritical annealed medium-Mn steel (Fe–0.10C–5Mn) was investigated during uniaxial tensile testing. In-situ observations under scanning electron microscopy, transmission electron microscopy, and X-ray diffraction analysis were conducted to characterize the progressive transformation-induced plasticity process and associated fracture initiation mechanisms. These findings were discussed with the local strain measurements via digital image correlation. The results indicated that Lüders band formation in the steel was limited to 1.5% strain, which was mainly due to the early-stage martensitic phase transformation of a very small amount of the less stable large-sized retained austenite (RA), which led to localized stress concentrations and strain hardening and further retardation of yielding. The small-sized RA exhibited high stability and progressively transformed into martensite and contributed to a stably extended Portevin–Le Chatelier effect. The volume fraction of RA gradually decreased from 26.8% to 8.2% prior to fracture. In the late deformation stage, fracture initiation primarily occurred at the austenite/martensite and ferrite/martensite interfaces and the ferrite phase.