喷油泵装配线中拧紧技术的研究及应用

本论文介绍了拧紧技术的原理和方法,以及拧紧技术在喷油泵装配线中的应用.最后说明了拧紧程序在喷油泵装配线中的程序防错方法.     

Decoupled 3D moment control using in-wheel motors

Vehicles equipped with in-wheel motors are being studied and developed as a type of electric vehicle. Since these motors are attached to the suspension, a large vertical suspension reaction force is generated during driving. Based on this mechanism, this paper describes the development of a method for independently controlling roll and pitch as well as yaw using driving force distribution control at each wheel. It also details the theoretical calculation of a method for decoupling the dynamic motions. Finally, it describes the application of these 3D dynamic motion control methods to a test vehicle and the confirmation of the performance improvement.     

非线性消亡过程的二元相关性

多元随机变量相关性在许多方面引起关注，本文在二元随机变量之间各水平正相关及负相关的定义和相互关系的基础上讨论非线性纯消亡过程的相关水平。     

防波堤箱筒型基础结构气浮拖运与负压下沉工艺

以天津港箱简型基础防波堤试验工程为例，介绍了防波堤箱简型基础新结构及基础结构气浮拖运和负压下沉的新工艺，实践证明：这种国内首次开发的新工艺，安全可靠，耗能少，操作简单，适用于淤泥质地质条件下的防波堤、导堤及护岸工程。     

浅析武广客专弹性链形悬挂中负弛度问题

对武广客运专线接触网安装中出现的负弛度现象进行了探讨和分析,总结出导致该现象的原因,并提出相应的改进建议。     

三相V／V接线牵引变压器负序电流分析

简述了三相V／V接线牵引变压器的结构特征，应用负序电流的一般表达式推导出V／V接线牵引变压器的负序电流，用曲线形式描述了高压侧电流不平衡度的变化规律，并对负序电流引起的不平衡问题进行分析。     

沙漠地区涵洞轻型井点降水施工技术

S313线兰嘎段LJ-11标位于内蒙占南部毛乌素沙漠腹地.地层为粉细砂.为完成涵洞基坑开挖任务.经方案比选采取轻型井点降水措施.主要介绍轻型井点降水的施工设计、井点管安设、降水、施工注意事项等内容,并分析了影响降水的各种因素.提出了改进降水效果的有效途径和措施,对类似工程有借鉴意义.     

钢-混凝土双面组合连续箱梁负弯矩区有限元分析

钢-混凝土双面组合箱梁是由两个H型钢作钢骨架,并与上下两块混凝土板组合形成的箱形截面,可用于连续梁的负弯矩区。推导得到了负弯矩区截面弹性刚度和塑性极限弯矩的计算公式。建立集中力作用下双面组合连续箱梁负弯矩区的Ansys分析模型,得到了组合梁的荷载挠度曲线、截面应力和应变变化曲线以及钢与混凝土交界面的纵向滑移分布。与双主梁组合梁和普通组合箱梁的受力性能做比较,显示了双面组合箱梁承载能力和变形能力的优越性。     

Experimental research on dynamic vibration absorber with negative stiffness for longitudinal vibration control of propulsion shafting system北大核心CSCD

［Objectives］In order to control the first longitudinal vibration mode of propulsion shafting systems, a dynamic vibration absorber with disc spring negative stiffness is proposed and its experimental verification carried out. ［Methods］A test bench is established for the propulsion shafting system containing a dynamic vibration absorber with negative stiffness. According to the first longitudinal vibration mode of the shafting, a dynamic vibration absorber with negative stiffness integrated into the thrust bearing is developed. Vibration transmission tests under different rotational speeds, static thrusts and negative stiffness are then carried out, and acceleration response data on the thrust bearing foundation and shafting is obtained. ［Results ］ The results show that the developed dynamic vibration absorber with negative stiffness can achieve vibration suppression of 7.8 dB for the thrust bearing foundation in the first longitudinal mode of the propulsion shafting with a mass ratio of 1.6%, and the vibration control effect of the negative stiffness dynamic vibration absorber is maintained at 3.3 dB when the natural frequency changes by 5% and the thrust changes by 40%. The vibration response on the thrust bearing foundation and shafting do not deteriorate even at non-optimal negative stiffness. ［Conclusions］This study shows that a dynamic vibration absorber with negative stiffness can effectively suppress vibration transmission at the first longitudinal mode of a shafting under different rotational speeds. © 2023 Authors. All rights reserved.     

南非规范与中国规范中汽车荷载对比研究

为给我国涉外桥梁工程项目设计提供参考,对我国与南非桥梁设计规范中汽车荷载效应进行对比研究。采用铰接板梁法和刚接梁法,计算常用跨径的单片简支梁在南非与中国规范汽车活载作用下的横向分布系数。在此基础上,通过对简支梁及整体式连续梁的纵向影响线加载,分析2种规范中考虑汽车活载纵、横向分布后的差异。对比发现,对于常用中小跨径的简支、连续梁,南非规范汽车活载效应均高出中国规范30%以上;对于简支T梁跨中截面及连续梁支点截面,南非规范汽车活载效应高出中国规范35%~80%。即便考虑到两国规范中汽车冲击效应计入方式的不同,南非规范汽车活载也大于中国规范规定值。