Clearance not only affects the startup torque,rotation precision and stiffness of bearing,but also affects the load distribution,load-carrying capacity and life of bearing.A computational model in which the clearance ...Clearance not only affects the startup torque,rotation precision and stiffness of bearing,but also affects the load distribution,load-carrying capacity and life of bearing.A computational model in which the clearance of bearing is first included is presented for determining the contact force distribution and static load-carrying capacity of a double row four-point contact ball bearing which is subjected to the combined radial,axial and overturning moment loadings.The relation between the negative axial clearance and the contact force distribution is analyzed.The static load-carrying capacity curves are established,and the effects of the changes in negative axial clearance,curvature radius coefficient of raceway groove and initial contact angle on the static load-carrying capacity are analyzed.The results show that,with the increase in the absolute value of negative clearance,the maximum contact load decreases first and then increases.The clearance values in the range of 0.2 mme0 mm have little effect on the static load-carrying capacity of bearing.With the increase in the curvature radius coefficient of raceway groove and the decrease in the initial contact angle,the static load capacity of bearing decreases.展开更多
在大规模数据中心和P2P覆盖网络等复杂网络负载平衡分配中,前人提出了多种多样的负载分配方法,但许多方法为了达到更好的平衡负载指标,追求越来越复杂的算法,使得时间复杂度和算法复杂度很难控制在合理的范围之内。本文在研究了经典ball...在大规模数据中心和P2P覆盖网络等复杂网络负载平衡分配中,前人提出了多种多样的负载分配方法,但许多方法为了达到更好的平衡负载指标,追求越来越复杂的算法,使得时间复杂度和算法复杂度很难控制在合理的范围之内。本文在研究了经典balls-into-bins、Azar balls-into-bins和balls into non-uniformbins等模型的基础上,提出了一种新颖高效的非对称balls-into-bins平衡负载分配模型,该模型具有异构的balls、异构的bins,以及不同的bin选择概率,能以很高的概率将最大负载均衡地控制在合理的范围内,通信负载很小,且具有很好的可扩展性,通过拓展,该模型在负载平衡的诸多领域都将有广阔的应用空间。展开更多
Load distribution in deep groove ball bearing has been studied in this work. A deep groove ball bearing model is proposed basing on geometry specific measurement. Two approaches (finite element method and semi-analyti...Load distribution in deep groove ball bearing has been studied in this work. A deep groove ball bearing model is proposed basing on geometry specific measurement. Two approaches (finite element method and semi-analytical) have been used to determine the distribution of an external radial force applied. These two approaches have been compared in terms of computation time and precision. At the second point, a deformable complex bearing housing has been integrated in the FEM ball bearing model to assess the influence of its deformation on load distribution.展开更多
急慢性负荷比作为新型的负荷管理手段,为降低运动损伤提供了新的思路。集体球类项目因具有开放性、对抗性的特征,多样的运动损伤发生率引起了急慢性负荷比研究关注。检索PubMed、Web of Science、EBSCO运动科学全文数据库,全面收集集体...急慢性负荷比作为新型的负荷管理手段,为降低运动损伤提供了新的思路。集体球类项目因具有开放性、对抗性的特征,多样的运动损伤发生率引起了急慢性负荷比研究关注。检索PubMed、Web of Science、EBSCO运动科学全文数据库,全面收集集体球类项目急慢性负荷比与损伤发生风险的队列研,共纳入文献19篇,样本量1185名高水平运动员,采用Stata17.0进行meta分析的数据处理。证实了急慢性负荷比>1时的损伤发展高于急慢性负荷比<1时(RR∶1.24,95%CI∶1.03~1.50,P<0.05BFQ)。亚组分析显示内部负荷测量下的急慢性负荷比对损伤的影响效果高于外部负荷;赛季中急慢性负荷比对损伤的影响要高于赛季前;橄榄球与足球项目不同急慢性负荷比所造成的损伤情况效应量相近;周期较长的急慢性负荷比对损伤影响效果明显高于短周期的急慢性负荷比;高于2.0的急慢性负荷比具有较高损伤致病风险。急慢性负荷比对运动损伤预防具体一定作用。展开更多
基金supported by NSFC(51105131)Excellent Youth Foundation of Henan Scientific Committee(124100510002)Creative Talent Foundation in University of Henan Province(2011HASTIT016)
文摘Clearance not only affects the startup torque,rotation precision and stiffness of bearing,but also affects the load distribution,load-carrying capacity and life of bearing.A computational model in which the clearance of bearing is first included is presented for determining the contact force distribution and static load-carrying capacity of a double row four-point contact ball bearing which is subjected to the combined radial,axial and overturning moment loadings.The relation between the negative axial clearance and the contact force distribution is analyzed.The static load-carrying capacity curves are established,and the effects of the changes in negative axial clearance,curvature radius coefficient of raceway groove and initial contact angle on the static load-carrying capacity are analyzed.The results show that,with the increase in the absolute value of negative clearance,the maximum contact load decreases first and then increases.The clearance values in the range of 0.2 mme0 mm have little effect on the static load-carrying capacity of bearing.With the increase in the curvature radius coefficient of raceway groove and the decrease in the initial contact angle,the static load capacity of bearing decreases.
文摘在大规模数据中心和P2P覆盖网络等复杂网络负载平衡分配中,前人提出了多种多样的负载分配方法,但许多方法为了达到更好的平衡负载指标,追求越来越复杂的算法,使得时间复杂度和算法复杂度很难控制在合理的范围之内。本文在研究了经典balls-into-bins、Azar balls-into-bins和balls into non-uniformbins等模型的基础上,提出了一种新颖高效的非对称balls-into-bins平衡负载分配模型,该模型具有异构的balls、异构的bins,以及不同的bin选择概率,能以很高的概率将最大负载均衡地控制在合理的范围内,通信负载很小,且具有很好的可扩展性,通过拓展,该模型在负载平衡的诸多领域都将有广阔的应用空间。
文摘Load distribution in deep groove ball bearing has been studied in this work. A deep groove ball bearing model is proposed basing on geometry specific measurement. Two approaches (finite element method and semi-analytical) have been used to determine the distribution of an external radial force applied. These two approaches have been compared in terms of computation time and precision. At the second point, a deformable complex bearing housing has been integrated in the FEM ball bearing model to assess the influence of its deformation on load distribution.
文摘急慢性负荷比作为新型的负荷管理手段,为降低运动损伤提供了新的思路。集体球类项目因具有开放性、对抗性的特征,多样的运动损伤发生率引起了急慢性负荷比研究关注。检索PubMed、Web of Science、EBSCO运动科学全文数据库,全面收集集体球类项目急慢性负荷比与损伤发生风险的队列研,共纳入文献19篇,样本量1185名高水平运动员,采用Stata17.0进行meta分析的数据处理。证实了急慢性负荷比>1时的损伤发展高于急慢性负荷比<1时(RR∶1.24,95%CI∶1.03~1.50,P<0.05BFQ)。亚组分析显示内部负荷测量下的急慢性负荷比对损伤的影响效果高于外部负荷;赛季中急慢性负荷比对损伤的影响要高于赛季前;橄榄球与足球项目不同急慢性负荷比所造成的损伤情况效应量相近;周期较长的急慢性负荷比对损伤影响效果明显高于短周期的急慢性负荷比;高于2.0的急慢性负荷比具有较高损伤致病风险。急慢性负荷比对运动损伤预防具体一定作用。
