高速受电弓气动减阻的仿真优化研究

随着绿色环保的现代轨道交通设计理念发展，受电弓减阻成为制约高速列车提速的关键问题之一。高速列车运行时，受电弓暴露于流线型车体之外，是列车气动阻力的主要来源之一，随着列车速度的提高，受电弓的减阻问题亟待解决。本文针对某型高速受电弓，基于计算流体动力学仿真技术，分析了整弓气动阻力分布，确定滑板与底座的压差阻力是气动阻力的主要来源，提出了滑板流线型减阻外壳与底座包裹流线型减阻外壳的优化方案，并与原模型对比验证了减阻效果。计算表明，减阻模型在350 km/h运行时，整弓气动阻力在开口、闭口时分别降低25.13%与24.19%

Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024

We present a measurement of the integrated luminosity e+e- of collision data collected by the BESIII detector at the BEPCII collider at a center-of-mass energy of Ecm = 3.773 GeV. The integrated luminosities of the datasets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 were determined to be 4.995±0.019 fb-1, 8.157±0.031 fb-1, and 4.191±0.016 fb-1, respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects, and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^