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The power transformer is a critical primary device in the power grid, and the verification of its winding mechanical stability is of paramount importance in ensuring the safe and stable operation of the power grid. In the conventional numerical calculation methods for verifying the mechanical stability of power transformer windings, the influence of temperature variations at the winding hot spots on winding mechanical stability has not been taken into account. In reality, factors such as the transformer’s operating load rate, ambient temperature, and the duration of short-circuit fault currents passing through will affect the mechanical stability margin of the transformer windings. Under conditions such as winding aging, deformation, or other reasons, the transformer windings may become unstable due to material parameter degradation, leading to insufficient mechanical stability margin. This paper analyzes the mechanical stability of power transformer windings considering the impact of the temperature field. Initially, a numerical model for calculating short-circuit currents in transformers was established to compute the short-circuit current under three-phase short-circuit-to-ground conditions as an excitation. Subsequently, a 3D electromagnetic force finite element calculation model was developed to determine the electromagnetic forces experienced under this condition. The results of the calculated electromagnetic forces were then used in a numerical calculation method to assess the mechanical stability of the windings. Furthermore, a 3D transformer electromagnetic–thermal flow finite element model was created to calculate the steady-state temperature rise under various operating conditions of the transformer. This model is validated through transformer temperature rise tests, and transient temperature rises under different operating conditions are calculated. The obtained data are fitted using the nonlinear least squares method to derive a fitting function for the winding hot spot temperature concerning load rate, ambient temperature, and short-circuit time. Taking into consideration the influence of temperature on the yield strength and modulus of elasticity of transformer winding materials, the variation in mechanical stability margin of transformer windings due to temperature effects is analyzed. Additionally, the operating domain for preventing the transformer from becoming unstable under three-phase short-circuit impacts is calculated for different degrees of material parameter degradation. This method provides an effective reference for transformer design and operation, demonstrating clear practical value.

Industrial heat sources (IHSs) are major contributors to energy consumption and environmental pollution, making their accurate detection crucial for supporting industrial restructuring and emission reduction strategies. However, existing models either focus on single-class detection under complex backgrounds or handle multiclass tasks for simple targets, leaving a gap in effective multiclass detection for complex scenarios. To address this, we propose a novel multiclass IHS detection model based on the YOLOv8-FC framework, underpinned by the multiclass IHS training dataset constructed from optical remote sensing images and point-of-interest (POI) data firstly. This dataset incorporates five categories: cement plants, coke plants, coal mining areas, oil and gas refineries, and steel plants. The proposed YOLOv8-FC model integrates the FasterNet backbone and a Coordinate Attention (CA) module, significantly enhancing feature extraction, detection precision, and operational speed. Experimental results demonstrate the model’s robust performance, achieving a precision rate of 92.3% and a recall rate of 95.6% in detecting IHS objects across diverse backgrounds. When applied in the Beijing–Tianjin–Hebei (BTH) region, YOLOv8-FC successfully identified 429 IHS objects, with detailed category-specific results providing valuable insights into industrial distribution. It shows that our proposed multiclass IHS detection model with the novel YOLOv8-FC approach could effectively and simultaneously detect IHS categories under complex backgrounds. The IHS datasets derived from the BTH region can support regional industrial restructuring and optimization schemes.

With advancements in cable manufacturing processes, the physical parameters of certain cable conductors fall outside of the scope specified by the IEC60287-1-1 standard, and the alternating current (AC) resistance calculated using the IEC standard may lead to reliability issues in the thermal evaluation of cable lines. Therefore, conducting an AC resistance test on cable conductors becomes critical for the thermal evaluation of cable lines. The source of error in the existing AC resistance test was analyzed first. It was found that the characteristics of the source used in the test lead to an error between the test value and the actual value of AC resistance. Moreover, an optimized AC resistance testing method based on active power was proposed to decrease the error. The accuracy of the method was also demonstrated. Finally, AC resistance tests were conducted on cable conductors with different cross-sectional areas, segmental methods, and oxidation methods by using the proposed method. The test results are also thoroughly discussed.

ABSTRACTCarbon‐interstitial compounds of precious metal alloys (Ci‐PMA) have attracted increased attention as effective catalytic materials, but their precise and controllable synthesis remains significant challenges. Herein, we have established a universal approach for the straightforward synthesis of supported Ci‐platinum group metal‐indium alloys (M3InCx, M = Pt, Pd, Ni, x = 0.5 or 1). The control experiment results indicate that the C atoms in Pt3InC0.5 come from the solvent. Furthermore, 0.2 wt.% Pt3InC0.5/SiO2 exhibits excellent catalytic performance for aqueous phase reforming (APR) of methanol (CH3OH) to produce hydrogen, with productivity and turnover frequency of 310.0 −1mol·kgcat·h−1 and 30 126 h−1 at 200°C, which are 1.7 times greater than those of Pt3In/SiO2. The infrared results of CH3OH adsorption reveal that the substantially better performance for APR of CH3OH of Pt3InC0.5/SiO2 than Pt3In/SiO2 is due to its significantly enhanced CH bond dissociation ability. This study not only provides a straightforward and universal approach for the controlled synthesis of Ci‐PMA but also stimulates fundamental research into Ci‐PMA for catalysis and other applications.

In recent years, the increased application of inverter-based resources in power grids, along with the gradual replacement of synchronous generators, has made the grid support capability of inverters essential for maintaining system stability under large disturbances. Critical clearing time provides a quantitative measure of fault severity and system stability, and its sensitivity can help guide parameter adjustments to enhance the grid support capability of inverters. Building on previous researches, this paper proposes a method for calculating critical clearing time sensitivity in power systems with a high proportion of power electronic devices, accounting for the new dynamic characteristics introduced by these devices. The current limit and switching control of inverter-based resources are considered, and the critical clearing time sensitivity under controlling periodic orbits is derived. The proposed critical clearing time sensitivity calculation method is then validated using a double generator single load system and a modified 39-bus system.

Abstract Background By exceeding planetary environmental boundaries, multiple global crises have become imminent in the 21st century. The healthcare system is a contributor to the climate crisis, accounting for approximately 5% of greenhouse gas emissions in Western countries. In anaesthetic clinics, desflurane, a highly potent greenhouse gas and volatile anaesthetic with no compelling indications, accounts for up to two thirds of total emissions. Its use can be drastically reduced using simple measures. In the present study, we investigated whether a relevant and timely reduction in use could be achieved by dismounting desflurane vaporisers and providing information to the team without restricting its use. Methods The study was conducted in a German university hospital with approximately 1250 beds, over a 12-month period between 2021 and 2022, with a comparison to the corresponding periods of the previous years up to 2017. The interventions were, first, the removal of desflurane vaporisers, and second, staff education on the climate impact of volatile anaesthetics. The primary outcome variable was the reduction of hypnotic-related emissions in CO2 equivalents per anaesthetic procedure. Results Prospective data collection and interventions were conducted from 28 March 2021 to 27 March 2022. The amount of CO2 equivalent emissions per procedure in the form of volatile anaesthetics was reduced by 86% compared with the year before the interventions (p < 0.001). Interestingly, there was already a 52.1% reduction in the year before the procedure (p < 0.001). There were no significant changes in the use of sevoflurane or propofol. Hypnotic-related costs decreased by €14,549, whereas extubation time did not change significantly. Conclusions Removal of desflurane vaporisers and staff training can quickly and significantly reduce the emissions of an anaesthesia department in a large German teaching hospital. This may also reduce the costs. Trial registration The trial was registered with the German Clinical Trials Register, identifier DRKS00024973 on 12/04/2021.

A persistent concealed non-Kekulé nanographene featuring two phenalene units fused in a cis configuration to a perylene core was successfully synthesized in solution and characterized.

Abstract Aqueous zinc batteries are attractive for large-scale energy storage due to their inherent safety and sustainability. However, their widespread application has been constrained by limited energy density, underscoring a high demand of advanced cathodes with large capacity and high redox potential. Here, we report a reversible high-capacity six-electron-conversion Se cathode undergoing a ZnSe↔Se↔SeCl4 reaction, with Br−/Brn − redox couple effectively stabilizes the Zn | |Se cell. This Se conversion, initiated in a ZnCl2-based hydrogel electrolyte, presents rapid capacity decay (from 1937.3 to 394.1 mAh gSe −1 after only 50 cycles at 0.5 A gSe −1) primarily due to the dissolution of SeCl4 and its subsequent migration to the Zn anode, resulting in dead Se passivation. To address this, we incorporate the Br−/Brn − redox couple into the Zn | |Se cell by introducing bromide salt as an electrolyte additive. The generated Brn − species acts as a dead-Se revitalizer by reacting with Se passivation on the Zn anode and regenerating active Se for the cathode reaction. Consequently, the cycling stability of the Zn | |Se cell is improved, maintaining 1246.8 mAh gSe −1 after 50 cycles. Moreover, the Zn | |Se cell exhibits a specific capacity of 2077.6 mAh gSe −1 and specific energy of 404.2 Wh kg−1 based on the overall cell reaction.