Transformers are indispensable components of modern power systems, and timely identification of core loosening faults is of great significance for ensuring reliable operation. In this study, a novel diagnostic approach is introduced that combines Hippopotamus Optimization (HO) with Feature Modal Decomposition (FMD). The HO algorithm is employed to optimize the parameter selection of FMD, enabling the extraction of representative fault-related features from vibration signals. These features are subsequently classified through a Temporal Convolutional Network (TCN). Experimental investigations indicate that the proposed method can accurately distinguish four loosening levels of the transformer core (0

A straightforward strategy was developed to immobilize atomically dispersed CuNx catalytic active sites on the surface of low-temperature carbonized agarose aerogel. This was achieved by first generating surface carbonyl groups on the aerogel substrate via thermal dehydration, which subsequently condensed in situ with bis(ethylenediamine)copper(I) iodide to form immobilized CuNx sites. The resulting heterogeneous copper catalyst is easily synthesized in quantitative yield on a large scale from inexpensive starting materials under mild conditions. Comprehensive characterizations, including IR, XPS, TG, synchrotron powder XRD, and spherical aberration-corrected TEM, confirmed the well-dispersed CuNx sites on the substrate surface. The immobilized CuNx sites demonstrated excellent catalytic performance in Ullmann-type diaryl ether formation. Among the catalysts prepared under varying conditions, AA-CuNx-200, synthesized at 200 degrees C in an argon atmosphere with a Cu content of 5.9 wt%, exhibited the highest catalytic activity. This catalyst efficiently converted diverse substrates into diaryl ether products within 24 h at 145 degrees C. The catalyst was easily separated by centrifugation and retained its catalytic activity after seven consecutive reaction cycles. This study underscores a universal method for preparing atomically dispersed CuNx active sites. By leveraging this method, it offers a scalable, efficient, and green approach to diaryl ether synthesis.

Due to their low greenhouse effect and exceptional insulating properties, C4F7N-CO2 gas mixtures have garnered significant attention. In particular, understanding the decomposition characteristics of C4F7N-CO2 is crucial for their practical use as an eco-friendly dielectric medium. At elevated temperatures, the pyrolysis of C4F7N produces high concentrations of CFN, CF3, and C2F2, along with lower levels of C3F5, C4F6N, C2F, and CN. A further increase in temperature may lead to the decomposition of CO2 into CO and additional components such as C2, C2F3, C3F4, C4F7 and C3F6, CF, CO, C3F7, C3F2, C3F, C3F3, C3F3N, C3, CF2, and CF2N. Under electrical discharge conditions, the decomposition of CO2 becomes more pronounced, forming products like CO, C2O, O2, C2O2, and C2O4, with up to 25 decomposition components observed. These include products originated from both C4F7N and CO2 and their combinations. In ultra-high electric field intensities, only small molecules such as O2, C2, C3, and N2 are detected among the decomposition products. This study aims to provide theoretical insights and valuable data to advance research into the decomposition behavior and practical engineering applications of C4F7N-CO2 gas mixtures under extreme conditions.

Mixed-matrix membranes (MMMs) are a promising solution for gas separation, and two-dimensional (2D) nanostructure fillers have been shown to effectively prevent common interfacial voids, significantly enhancing gas separation efficiency. However, preparing ultra-thin metal-organic framework (MOF) nanosheets with high homogeneity remains a significant challenge. Here, we demonstrated a 2D MOF, IPM-1, with extremely weak interlayer interactions, can be facilely exfoliated into ultra-thin nanosheets with a thickness of 2-5 nm and a lateral size of up to 10 mu m. The high aspect ratio and abundant heteroatom sites enable the uniform dispersion of IPM-1 nanosheets within the polyvinyl acetate (PVAc) matrix, effectively avoiding the formation of typical interfacial voids. The resulting MMMs demonstrated high efficiency in removing oxygen from perfluoroisobutyronitrile (C4), an ideal environmentally friendly alternative to SF6 as an insulating gas. Oxygen often acts as a readily mixed impurity, deactivating the insulating gas. The incorporation of IPM-1 nanosheets into PVAc significantly improved the permeability and selectivity of the MMMs for the O2/C4 gas mixture. Specifically, the dense PVAc membrane exhibited an enhanced permeability of 0.59 Barrer and an O2/C4 separation factor of 24 with an 8 wt% IPM-1 nanosheet loading. These MMMs are thermally stable and mechanically robust, maintaining their high C4 separation performance during long-term operational testing. This excellent performance can be attributed to the synergy of enhanced compatibility, solubility, diffusivity, and size selectivity for gas molecules within the nanosized pores, providing a practical and effective method for in-situ separation and purification of C4 gas in industrial applications.

SF 6 is widely used as an insulation and arc extinguishing medium in the power industry. However, its high thermal stability also makes it very difficult to convert into other chemicals, greatly limiting its resource utilization. This article proposes four possible reaction pathways for the resource utilization of SF 6 , and explores their thermodynamic and commercial feasibility through theoretical calculation methods. The results showed that: (1) SF 6 needs to first remove one molecule of F 2 to generate SF 4 , and then undergo subsequent conversion. This reaction step requires a significant amount of endothermic energy, making it relatively difficult to carry out. It may necessitate conditions such as electrical discharge or illumination to proceed; (2) The preparation of fluorinating reagent XtalFLuor-E by the joint reaction of SF 4 , ethylenediamine, and Boron trifluoride etherate is thermodynamically feasible and has certain commercial value. This reaction has high feasibility and deserves further in-depth study.

Owing to the low greenhouse effect and excellent insulating properties, C 4 F 7 N gas has been paid more and more attentions in recent years. The insulation failure of C 4 F 7 N in a trace water environment after discharge is very important for its practical applications. Here, density functional theory (DFT) calculation methods were employed to electron-scale investigation of C 4 F 7 N decomposition with the assistance of H 2 O. Different possible reaction paths were analysed from the view of thermodynamic and dynamic. The reaction path, in which the H· attacked the centre F atom in C 4 F 7 N molecule, is the most favourable. And the C≡N group dissociation from C 4 F 7 N is relatively difficult. The H, instead of OH, can promote the decomposition reaction of C 4 F 7 N. The results reveal the C 4 F 7 N decomposition from the electron scale, which is helpful for understanding the insulation failure of C 4 F 7 N due to water and guiding its exploration in the electrical field.

The equalizing electrode is a key component of the converter valve. Aiming at the problem of monitoring the fouling conditions of them, a non-contact detection method based on the infrared light transmittance characteristics of polyvinylidene fluoride (PVDF) material is proposed. By screening the suitable infrared wavelength (940 nm), an infrared optical detection device integrating light source control, optical imaging, and image processing modules was designed. The device adopts a 45-degree reflector and a compact structure design, which improves the flexibility and applicability in limited spaces. During the annual inspection of Baoji Converter Station, a field detection validation was conducted, achieving a test accuracy of 0.1 mm with an error controlled within $\pm 5 \%$.

By immobilization FeN x sites on the porous substrate surface, stable atomically dispersed iron electrocatalyst with high-performance and high-metal content was rationally produced in quantitative yield and large-scale via a simple two-step process.

It is necessary to take out the electrode when detecting the scaling degree of the conventional grading electrode. The steps are cumbersome and there are safety risks. In this paper, through the analysis of the equivalent circuit model before and after the scaling of the grading electrode on the cooling water manifold in the converter valve, the loop resistance model suitable for the positive and negative potential sides is obtained. The constant voltage DC source is used as the driving voltage of the circuit, and the leakage current of the circuit is measured under different temperatures and conductivity conditions of the internal cooling water. The degree of scaling of the grading electrode is determined by analyzing the leakage current. The leakage current in the non-scaling state of the grading electrode and the leakage current in the scaling failure state of the grading electrode are taken as the reference values. It is concluded that when the leakage current of the measurement circuit decreases to 68 % - 80 % of the leakage current in the non-scaling state of the grading electrode, the grading electrode can be considered to fail.

Generally, the thermal conductivity of gas insulation medium is generally worse than that of liquid insulation medium. The heat dissipation problem is the key to developing large-capacity gas-insulated transformers. The traditional SF 6 gas-insulated transformers are facing the challenge of upgrading and updating due to the strong greenhouse effect of SF 6 . As an ideal substitute gas for SF 6 , i-C 4 F 7 N/CO 2 gas mixture is used as a new insulation medium to develop eco-friendly gas-insulated transformers. In this work, we described the structure and parameters of 10 kV GIT and measured the temperature and pressure by mounting sensors in different parts of 10 kV GIT. Further, we analyzed the heat dissipation performance of the Transformer based on the pressure and temperature data. The results show that the GNAN cooling mode may not be applicable to eco-friendly GITs with large capacities and high loads.

Nonprecious-metal heterogeneous catalysts with atomically dispersed active sites demonstrated high activity and selectivity in different reactions, and the rational design and large-scale preparation of such catalysts are of great interest but remain a huge challenge. Current approaches usually involve extremely high-temperature and tedious procedures. Here, we demonstrated a straightforward and scalable preparation strategy. In two simple steps, the atomically dispersed Ni electrocatalyst can be synthesized in a tens grams scale with quantitative yield under mild conditions, and the active Ni sites were produced by immobilizing preorganized NiNx complex on the substrate surface via organic thermal reactions. This catalyst exhibits excellent catalysis performances in both oxygen evolution and reduction reactions. It also exhibited tunable catalysis activity, high catalysis reproducibility, and high stability. The atomically dispersed NiNx sites are tolerant at high Ni concentration, as the random reactions and metal nanoparticle formation that generally occurred at high temperatures were avoided. This strategy illustrated a practical and green method for the industrial manufacture of nonprecious-metal single-site catalysts with a predictable structure.

By immobilizing the metal complex on the substrate surface, our previous results have demonstrated that heterogeneous catalysts with well-dispersed active MNC (metal-nitrogen-carbon) sites can be prepared in a rational and efficient manner. In this study, we employed agarose aerogel (AA) as the substrate to illustrate a straightforward strategy for immobilizing ZnNx sites on the surface. Under relatively low temperatures, the amine group of the ligand condenses with the surface carbonyl group generated in situ, resulting in the surface immobilized Zn sites. This can be supported by the IR, PXRD, and XPS data. Comprehensive characterization methods, including synchrotron powder XRD and spherical aberration-corrected TEM, confirmed the absence of ZnNx site aggregation in the surface immobilization process, even with a high Zn content (up to 8 wt %). The immobilized ZnNx sites exhibited high catalytic performance in Knoevenagel condensation, and alpha,beta-unsaturated compounds were obtained with high yield in both batch and continuous flow reactions. AA-ZnNx-200 showed the best catalytic activity, which was processed under 200 degrees C with a Zn content of 4.62 wt %. The immobilized ZnNx sites activated both the aldehyde and nitrile substrates, which were quantitatively converted into the corresponding alpha,beta-unsaturated compounds, with water as the solvent at room temperature. In continuous flow reaction conditions, a conversion rate up to 99% can be achieved with malononitrile. This heterogeneous catalyst can be facilely produced with quantitative yield in a large scale from cheap starting material under mild conditions. No catalyst deactivation was observed after seven batch reaction cycles or 80 h of continuous flow reaction, indicating its high robustness under catalytic reaction conditions. This catalyst enables a separation-free, energy-saving, and environment-friendly production process, offering a practical way for the industrial production.

Global warming is a huge challenge for the survival of humanity. SF6 as a super greenhouse gas is facing the end of being eliminated. (CF3)2CFCN and C5F10O as the substitute for SF6, the evaluation of the impact on climate change depends on the calculation of GWP. In this work, we introduced and summaried the calculation and testing principles of GWP. Further, the radiative efficiencies of (CF3)2CFCN and C5F10O were calculated by using the revised Pinnock curve based on the Oslo line-byline (LBL) model and density functional theory. Finally, we calculated the the global warming potential of (CF3)2CFCN and C5F10O based on the experimental values of the atmospheric lifetime and radiative efficiencies. The results show that the contribution of (CF3)2CFCN to climate change is significantly lower than that of SF6.

The development of heterogeneous catalyst with well-dispersed active metal sites is one of the hottest research topics. By properly choosing or designing the host material to stabilize the active sites, host-engineering strategy is commonly applied for the preparation of quasimolecular heterogeneous catalysts. Here, by doping the metal-organic framework (MOF) Co-BPDC with 4-(4'-formylphenyl)benzoic acid, ultrathin nano sheets with an aldehyde group-modified surface were facially produced. Upon the addition of ethylenediamine, the surface aldehyde group was converted into imine groups in situ. At this stage, the Co-BPDC nanosheet still had relatively poor catalytic activity in oxygen evolution reaction (OER). After metalation with Fe3+ under ambient conditions, the catalytic activity was greatly enhanced for the resulting nanosheet. With a surface Fe content of 2.87 wt %, the observed electrochemical overpotential and Tafel slope for the Co-BPDC nanosheet in OER decreased to 291 mV and 38 mV/decade, respectively. Meanwhile, the nanosheet catalyst also showed moderate catalytic stability. By taking advantage of the ultrathin nanosheet, the catalytic active Fe sites were immobilized on the nanosheet by the surface imine ligands. This strategy enables the economical and facial production of an atomically dispersed metal catalyst in a large scale under ambient conditions. With the easily accessible and modifiable large surface, the ultrathin MOF nanosheet is an ideal host material for anchoring active metal sites after surface modification.

(CF3)2CFCN-CO2 gas mixture is an eco-friendly alternative to SF6. Investigating its compatibility with solid materials used in gas transformers and promoting the application of (CF3)2CFCN-CO2 gas mixtures are of great significance for power grid companies and power systems to achieve carbon emission reduction and carbon neutrality. At present, there are few reports on the compatibility. This paper proposed the test method of the compatibility between gas mixtures and solid materials, set up the compatibility test platform and investigated the thermal stability of the 9%(CF3)2CFCN-91%CO2 gas mixture. The thermal accelerated aging test of the 9%(CF3)2CFCN-91%CO2 gas mixture and 12 kinds of solid materials at different temperatures was carried out. The results of the thermal stability test show that the initial decomposition temperature of the gas mixture in the 316L stainless steel sealed tube is 300 deg C. The initial decomposition temperature of the gas mixture in the quartz sealed tube is 400 deg C. The material of the sealed tube has a great influence on the initial decomposition temperature of the gas mixture. The results of the material compatibility test show that the 9%(CF3)2CFCN-91%CO2 gas mixture couldn’t react with 12 kinds of solid materials in the range of 40 deg C to 110 deg C. That is to say, the compatibility between the gas mixture and 12 kinds of solid materials is good in the range of 40 deg C to 110 deg C.

Abstract Nonprecious-metal catalysts with atomically dispersed active sites demonstrated high activity and selectivity in a series of catalysis reactions, the rational design and massive synthesis of such catalysts are of great interest but remains a huge challenge. Current approaches often require harsh conditions and tedious procedures. Here, we demonstrated a facile and scalable preparation strategy by anchoring pre-organized NiNx site on the surface of a layered Co-methylimidazole coordination compound. In two simple steps, single-site Ni electro-catalyst can be synthesized up to kilogram-scale with a yield of 75% under mild conditions. This catalyst exhibits excellent catalysis performances in both oxygen evolution and reduction reactions. Besides, it has tunable catalysis activity, high catalysis reproducibility and stability. The atomically dispersed NiNx sites are tolerate with high Ni concentration, indicating that the random reactions or metal nanoparticle formation generally observed at high temperature were avoided. This strategy presents a practical and green method for the industrial manufacture of nonprecious-metal single-site catalysts with predictable structure.

Ultrathin covalent organic framework (COF) nanosheets are very appealing 2D materials, but the mass production of ultrathin COF nanosheets remains a great challenge. Here, by using cage-like bicyclocalix[2]arene[2]triazines tri-aldehyde (BCTAL) as the building block, 2D COF Cage-COF-1 was estimated to have a very weak interaction between adjacent layers (around 1/50 compared to that of graphite). As a result, 1.2 nm thick trilayer COF nanosheets were facilely exfoliated from the pristine COFs with large lateral size and high thickness homogeneity. The Cage-COF-1 nanosheet is featured by imine linkage, but it is catalytic inactive in oxygen evolution reaction (OER). After post-metalation with Co2+ under ambient conditions, remarkable catalysis activity and stability was observed for Cage-COF-1-Ns/Co, which has lower overpotential (330 mV) and Tafel slope (56 mV/dec) in catalytic OER compared to many other Co catalysts. This work has confirmed that weakening the interlaminar interaction is an effective strategy for the production of ultra-thin COFs nanosheets. Due to the fully exposed and accessible imine linkage, catalysis active metal site can be controllably produced via post-synthesis from nanosheets under very mild conditions.

Heterogeneous atomically dispersed catalysts can be easily separated after the reaction with a maximum atom utilization efficiency. As one kind of very important organic intermediate, the development of cheap and efficient heterogeneous catalyst is highly desirable for the synthesis of 13-nitro alcohols. By immobilizing the nickel nitrogen complex on the surface of a 2D layered substrate, carbon-based single-site Ni catalyst was synthesized in large scale with quantitative yield under mild conditions. With the single nickel sites, aromatic aldehydes and nitromethane were converted into 13-nitro alcohols with a yield up to 99% under room temperature, no additive is needed. Due to the steric effect of the surface, diastereoselectivity (syn/anti ratio up to 3.5:1) was observed with the 13-nitro alcohols produced from nitropropane. The surface immobilized active Nickel sites can be easily separated from the product, negligible performance reduction was observed after five reaction cycles. This atomically dispersed Ni catalyst also can be produced facially in large batch under mild conditions, very close catalysis performance was observed with different batches. In hence, an energy saving and easy separation strategy was developed for the production of 13-nitro alcohols.

Global warming is a severe test facing the international community. As a serious greenhouse gas, the emission of SF6 has been restricted. In recent years, more and more experts and scholars have turned their attention to alternative gases of SF6. C5F10O(GWP<1) as an alternative gas is investigated by scientists due to good dielectric properties and weak greenhouse effect in recent years. In the first part, this review introduced the background of SF6 and C5F10O. In the second part, we elaborated on four synthetic methods of C5F10O. Trifluoroacetyl fluoride is the key raw material, CsF is an important catalyst. In the third part, the review presented the dielectric and arc interruption properities of C5F10O and its mixtures. The addition of O2 can increased the breakdown voltage of gas mixture. Finally, the decomposition mechanism and products of C5F10O，C5F10O/CO2 or C5F10O/N2/O2 gas mixtures are reviewed.