Accurate calculation of short-circuit (SC) dynamic characteristics of power transformer windings is of great significance to the safety of transformers. A 110 kV power transformer model is established, and SC electromagnetic characteristics and dynamic characteristics of the transformer windings are obtained through magnetic-structural coupling analysis by the finite-element method, considering the nonlinear mechanical characteristics of spacers. The distribution of leakage magnetic field and electromagnetic force (EF) and dynamic stress and displacement of windings are calculated due to SC fault. The SC EF of windings decreases exponentially with time. The axial EF of the disks at both ends of the winding is larger, while the radial EF is smaller, compared with that of central disks. The variation law of winding stress and displacement is similar to dynamic EF. The stress and displacement at both ends of the winding are larger while that in the middle part is smaller. The maximum stress and displacement of the end of windings are nearly 60% and 90% higher than that of the middle part, respectively. The axial displacement is the major part of the total displacement. The analysis method can provide a reference for checking the SC strength of the transformer.

RhoB, a member of the Ras homolog gene family and GTPase, regulates intracellular signaling pathways by interfacing with epidermal growth factor receptor (EGFR), Ras, and phosphatidylinositol 3-kinase (PI3K)/Akt to modulate responses in cellular structure and function. Notably, the EGFR, Ras, and PI3K/Akt pathways can lead to downregulation of RhoB, while simultaneously being associated with an increased propensity for tumorigenesis. Functionally, RhoB, part of the Rho GTPase family, regulates intracellular signaling pathways by interfacing with EGFR, RAS, and PI3K/Akt/mammalian target of rapamycin (mTOR), and MYC pathways to modulate responses in cellular structure and function. Notably, the EGFR, Ras, and PI3K/Akt pathways can lead to downregulation of RhoB, while simultaneously being associated with an increased propensity for tumorigenesis. RHOB expression has a complex regulatory backdrop consisting of multiple histone deacetyltransferase (HDACs 1 and 6) and microRNA (miR-19a, -21, and -223)-mediated mechanisms of modifying expression. The interwoven nature of RhoB’s regulatory impact and cellular roles in regulating intracellular vesicle trafficking, cell motion, and the cell cycle lays the foundation for analyzing the link between loss of RhoB and tumorigenesis within the context of age-related decline in RhoB. RhoB appears to play a tissue-specific role in tumorigenesis, as such, uncovering and appreciating the potential for restoration of RHOB expression as a mechanism for cancer prevention or therapeutics serves as a practical application. An in-depth assessment of RhoB will serve as a springboard for investigating and characterizing this key component of numerous intracellular messaging and regulatory pathways that may hold the connection between aging and tumorigenesis.

Infrared imager is widely used in substation inspections for early fault warning. However, infrared images have less texture information and large imaging differences in multiple states, which may lead to false or missed detection. This article proposed a disconnector state evaluation method based on infrared and visible images. This method combines the advantages of these two data sources and realizes individual-level temperature analysis. First, an optimized model disconnector-YOLOv4 (D-YOLOv4), with fewer model parameters and better detection performance than YOLOv4, is proposed to identify and locate the disconnectors in visible images. Experiments show that mean Average Precision (mAP)@0.5 of the optimized model is 92.86% and frames per second (FPS) is 105. Second, the detected area is mapped to the infrared image by image registration. Here, to address the problem arising from the different imaging characteristics of visible and infrared images, edge detection and affine transformation are introduced to extract the common features and complete image transformation. Third, we fit a $T$ – $g$ function to convert RGB value to temperature, and then the final state evaluation is conducted depending on the required standard. Experiments prove the feasibility and superiority of the proposed algorithm, which adapts the development demand of intelligent power substations, and the tendency of predictive maintenance.

An accurate analytical model for litz-wire (LW) winding loss calculation of power electronic transformers (PETs) was deduced. First, the skin effect and proximity effect losses at bundle levels of a single straight LW were introduced. Then, the proximity loss of an air-core LW winding was studied by adopting the coordinate transformation technique (CTT) considering helical winding (HW) configurations and twisting configurations (TCs). Last, a 2-D analytical model for LW windings considering magnetic materials, LW configurations, and winding configurations (WCs) was proposed with the help of CTT, Dowell method, and Roth's method. This model is helpful for the design of LW windings considering more details such as the choices of WCs and LW configurations.

We report a dramatic enhancement of random lasing assisted by Au nanocube-silica core-shell nanoparticles (Au NC@SiO₂ NPs) with optimal size. To determine which size of Au NC@SiO₂ NPs would have the optimal plasmon effect, we first investigated the lasing properties based on different sizes of bare Au nanocubes (Au NCs) with different localized surface plasmon resonance (LSPR) spectra; the edge lengths of the Au NCs ranged from 20 nm to 120 nm. The 80 nm Au NCs, whose LSPR spectrum had the largest overlap with the emission spectrum of the gain medium, exhibited the strongest scattering and electric field intensity to better enhance the lasing. Compared to the gain media with bare Au nanocubes or Au nanosphere@SiO₂ nanoparticles, the gain medium with optimally sized Au nanocube @SiO₂ NPs had the lowest lasing threshold, only 21.7% of that of the neat gain medium. This was attributed to the stronger scattering and electric field enhancement localized at the spiky tips of the Au NCs, and the fact that the SiO₂ shell reduced the absorption loss of the dyes in close proximity to the Au NCs. Using the proper size of Au NC@SiO₂ NPs provides an ideal way to achieve low-threshold plasmon random lasing by tuning the LSPR of metallic nanostructures.