Study on Vibration Characteristics of Wheeled Tractor Power Output Assembly

通过对大功率轮式拖拉机动力输出总成系统的激励分析、振动模态分析以及对系统固有特性的研究,分析了轴不平行度几何因素对总成系统的振动影响,研究了轴承游隙、轴承预紧力等物理因素对总成系统的固有特性影响。通过将轴承游隙、轴承预紧力控制在一个合理范围内,降低了系统的固有频率,减小了动力输出总成系统的振动。Based on the excitation analysis and vibration modal analysis of a large power wheeled tractor power output assembly system and study of the system intrinsic characteristics,the influence of shaft nonparallelism on assembly system vibration is analyzed. In addition,the influence of physical factors such as bearing clearance and bearing preload on inherent characteristics of the assembly system is studied. By controlling the bearing clearance and bearing preload within a reasonable range,the natural frequency of the system is reduced,and the vibration of the assembly system is also reduced.工信部智能制造专项“新型轮式拖拉机智能制造新模式应用”（豫洛工业制造[2016]07744

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^