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The oil-immersed transformer is a crucial piece of equipment in the power system. Operating at the specified temperature is necessary to ensure the normal operation of the transformer. The insulation paper on the winding surface has a significant impact on the actual temperature of the transformers, which is often overlooked by researchers. The one-dimensional steady-state heat conduction model of the transformer is established by analyzing the heat diffusion process of winding to transformer oil. Atomic force microscope was used to observe the microsurface structure of insulation paper and copper. According to the experiment, the heat transfer resistance in the series process of heat transfer at 7 0 ∘ C is 0.0138 m2 K/W. Space thermal circuit model of transformer is established by thermoelectricity analogy method, and the simulation circuit is optimized according to the boundary conditions set up in the actual environment. The results show that the error of the hot spot temperature is closer to the measured temperature and decreases by 2.5% when considering the thermal resistance of insulation paper. [ABSTRACT FROM AUTHOR]

Competing Interests: Conflict of interest: None declared.

Introduction: Decisions regarding the optimal timing of intervention for asymptomatic aortic stenosis (AS) are controversial. The study aims to identify potential risk factors for asymptomatic patients with severe AS that are associated with worse prognosis and to evaluate the benefits of early interventions for asymptomatic patients presenting with one or more additional risk factors., Methods and Analysis: This is a non-interventional, prospective, open-label, multicentre registry study across China. A total of 1000 patients will be enrolled and categorised as symptomatic or asymptomatic. The primary endpoint is the occurrence of all-cause mortality, stroke, acute myocardial infarction and heart failure-related hospitalisation at 1-year follow-up. In asymptomatic severe AS patients presenting with one or more risk factors, the occurrence rate of the primary endpoint between those who undergo transcatheter aortic valve replacement (TAVR) and those who do not will be compared. We will also compare the occurrence rate of the primary endpoint for asymptomatic severe AS patients with additional risk factors who undergo TAVR with those presenting with symptoms. This study is believed to provide additional evidence to help clinicians identify and refer severe AS patients who are asymptomatic but present with additional risk factors for early intervention of TAVR., Ethics and Dissemination: The study protocol has been approved by the local ethics committee of each participating site: West China Hospital, Sichuan University; Sir Run Run Shaw Hospital, Zhejiang University School of Medicine; Second Hospital of Hebei Medical University; Tianjin Chest Hospital; and First Affiliated Hospital of Nanchang University. All participants will provide written informed consent. Study results will be published through academic conferences and peer-reviewed journals., Trial Registration: This study was registered at the Chinese Clinical Trial Registry (https:// www.chictr.org.cn), with the registration number ChiCTR2200064853., Competing Interests: Competing interests: Dr Chen and Feng are consultants and proctors for Venus MedTech, MicroPort and TaurusOne. All other authors have nothing relevant to disclosure., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Competing Interests: Conflict of interest: None declared.