Due to high humidity, the ageing of room temperature vulcanized silicone rubber (RTV) has been a serious problem in Southwestern China. In order to solve the problem of RTV life prediction, the aging classification method was established by analyzing the microtopography of RTV samples in this paper. Besides, the comprehensive analysis of RTV element content, partial element content ratio, and major chemical groups of RTV samples in each aging level were conducted. It is found that as the ageing level increases, the element contents of C, Si, O, Al change accordingly and the ratio of C:Si drops from 2.39 to 1.54, and absorption peaks of the chemical groups of Si-(CH3)2, Si-O-Si, Si-CH3 and C-H in CH3 decrease. This work can enrich the investigation of RTV, and may provide useful reference for performance evaluation and replacement of RTV in substations.

The surface conductivity of the pollution layer plays a pivotal role in the investigation of flashover voltage and the propagating mechanism of the local arc. In order to study the characteristics of the pollution layer, an experimental system is designed in this paper. Ferric chloride is employed as the color indicator for demonstrating the dry state distribution of the pollution layer. Thus, the surface conductivity is calculated by analyzing the red–green–blue value of the pollution layer. In addition, a numerical model for calculating the heat transfer on the surface of the pollution layer is also established. It has been revealed that the dry state distribution of the pollution layer is affected by the leakage current and the speed of the local arc. Moreover, the relationship between the surface conductivity of the pollution layer and the thickness of the surface water film is obtained. The comparative analysis shows that the calculated results are in good agreement with the experimental data.

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From laboratory experiments it was shown that the flashover voltage of the wet contaminated insulator was significantly influenced by the parameters of the local arc. An integrated optical and electrical diagnostic platform was designed in this paper, which was used to acquire the emission spectrum and electrical parameters of the AC local arc over the wet contaminated surface. The analysis of thermodynamic and electric results showed that AC local arc had a “static time-varying” feature. Hence, a new characterization method of volt–ampere characteristics of the AC local arc was proposed, and a time constant was introduced to describe the time required for the AC local arc to reach the stable state from the beginning. The relationship between the voltage gradient of the AC local arc and the leakage current amplitude was obtained for flashover voltage calculation. Special attention was also paid to the influence of environmental factors, such as air pressure and ambient temperature, on the arc characteristic. This work can enrich the investigation of the parameters of the local arc over the wet contaminated insulation surface and may provide useful parameters for flashover voltage calculation of insulators in service.

Background:The treatment of diabetes-related foot complications is a clinical challenge. The underlying complicating factors of peripheral vascular disease render most diabetic foot ulcers asymptomatic until the ulcer fails to heal and becomes clinically distinct, constituting a significant cause of disability and even death in diabetic patients. Objective: To evaluate the clinical efficacy of tibial transverse transport (TTT) in the treatment of patients with diabetic foot ulcers. Methods: A total of 35 patients who met the inclusion criteria were selected as the study group from patients with diabetic foot ulcers diagnosed and treated at our hospital between August 2019 and March 2021 and were treated with TTT, and 35 patients who also met the inclusion criteria were included in the routine group and were given conventional wound debridement. The primary endpoint of this study was clinical efficacy, including pain condition, trauma condition, ankle-brachial index, and peripheral nerve recovery. Results: Patients receiving TTT showed significantly reduced visual analogue scale (VAS) scores than those with conventional treatment (P<0.05). TTT resulted in a significant reduction of trabecular area and better trabecular healing versus conventional treatment (P<0.05). TTT was associated with significantly higher ankle-brachial index (ABI) and lower Michigan neuropathy screening instrument (MNSI) scores in patients versus conventional debridement (P<0.05). Conclusion: TTT effectively alleviates the pain of diabetic foot ulcer patients, promotes wound healing, and improves ankle-brachial index and peripheral nerve recovery. In the context of the high amputation rate of diabetic foot ulcers treated by internal medicine, TTT contributes positively to the enhancement of patient prognosis and merits clinical promotion.