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Journal of Zhejiang University SCIENCE A

ISSN 1673-565X(Print), 1862-1775(Online), Monthly

Numerical study of wheel–rail adhesion performance of new-concept high-speed trains with aerodynamic wings

Abstract: Wheel‍–‍rail adhesion is a complex tribological problem of wheel‍–‍rail rolling contact and is closely related to the operational safety of high-speed trains. A new design concept of high-speed trains was recently proposed with an expectation of a reduction of equivalent weight and total energy consumption by installing aerodynamic wings (aero-wings) on the roof, but it was accompanied by the disadvantage of deteriorating wheel‍–‍rail adhesion performance. In this study, a comprehensive multi-body dynamics (MBD) model of the high-speed train with predesigned aero-wings is established using the commercial software SIMPACK, in which the real aerodynamic characteristics of the train are taken into account. The available adhesion and adhesion margin are employed to evaluate the wheel‍–‍rail adhesion performance. The influences of aero-wing lift, train speed, and contact conditions on the wheel‍–‍rail adhesion level are discussed. The results show that the load transfer caused by the action of aerodynamic load and braking torque was the main reason for the inconsistent adhesion condition of four wheelsets. The influences of aero-wing lift and train speed on the wheel‍–‍rail adhesion performance are coupled; the available adhesion of both motor car and trailer is negatively correlated with aero-wing lift and train speed under all contact conditions, while the variation law of adhesion margin with train speed shows differences under different contact conditions. When the wheel–rail interface was polluted by a ‘third-body medium’ such as water and oil, the wheel–rail adhesion performance was dramatically reduced and the wheelset tended to reach adhesion saturation and slide. However, track irregularity had little effect on the adhesion performance and could be ignored to save calculation time. These results are of positive significance for reducing the wheel idling or sliding phenomenon and to ensure the safe operation of high-speed trains with aero-wings.

Key words: High-speed train; Wheel–rail adhesion; Aerodynamic wing; Multi-body dynamics (MBD)

Chinese Summary  <20> 一例由2019冠状病毒病(COVID-19)疫苗接种引发的白癜风病例及其胸腺功能障碍的作用机制分析

Denis KUZNETSOV1,Oleg KALYUZHIN2,Andrey MIRONOV1,Valery NESCHISLIAEV3,Anastasiia KUZNETSOVA3
1G.N. Gabrichevsky Scientific and Research Institute of Epidemiology and Microbiology, Moscow 125212, Russia
2I.M. Sechenov First Moscow State Medical University, Moscow 119991, Russia
3Perm State Pharmaceutical Academy, Perm 614990, Russia
摘要:最近,人们发现接种2019冠状病毒病(COVID-19)疫苗后出现了大量并发症,影响心脏、肾脏、胰腺、关节和皮肤。本文结合已报道的11例COVID-19疫苗(主要与信使RNA(mRNA)疫苗有关)接种后白癜风病例的数据和我们自己接种的1例非复制载体疫苗后的白癜风病例,分析探讨了其相关的病理机制。根据常见的原理,自身免疫性病变是通过病毒的抗原表位与某些人类蛋白质之间的分子模拟诱发的。我们认为这一过程的基础是胸腺负选择的破坏,导致自身反应性T细胞迁移到外周。在本文中,我们证实了疫苗和/或感染以及黑素细胞氧化应激是自身免疫反应的主要诱因。在这种情况下,白癜风的发病机制可被视为糖尿病或动脉粥样硬化等多种自身免疫性疾病发病机制的模型。此外,我们概述了一种病理机制,其中黑色素细胞氧化应激、自身反应性T细胞和胸腺功能障碍可作为干预策略的潜在目标。

关键词组:白癜风;2019冠状病毒病疫苗;皮质醇;去氢表雄酮;自身反应性T细胞;维生素D3


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DOI:

10.1631/jzus.A2300025

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On-line Access:

2024-08-27

Received:

2023-10-17

Revision Accepted:

2024-05-08

Crosschecked:

2023-08-18

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