汽车爆胎对运动状态的影响研究

汽车爆胎是一种极其危险的工况,通过数学公式难以准确表达爆胎轮胎的力学特性,试验研究难度较大。文章以Carsim软件中的205/45 R17型轮胎为载体,通过对爆胎轮胎参数进行修正,建立了Carsim内置轮胎爆胎模型。通过仿真计算,车辆发生爆胎会导致汽车偏离预期道路,车身向爆胎轮胎侧偏转,爆胎轮胎纵向力及侧偏力剧烈变化,导致受爆胎影响最大的轮胎纵向力变大3.5倍,侧偏力变大10.5倍,仿真结果为爆胎车辆稳定性控制研究提供了基础。     

考虑泊松效应的单桩竖向承载变形特性研究

单桩在承受上拔或下压荷载时,其桩侧极限摩阻力相差较大,桩身泊松效应是重要的影响因素之一.考虑泊松效应对桩-土界面法向应力的影响,推导得到上拔与下压荷载作用导致的桩侧极限摩阻力改变量的表达式;根据双曲线荷载传递模型,得到考虑泊松效应的的τ-z曲线;在位移协调法的基础上,通过迭代更新桩底位移使桩顶轴力与桩顶荷载相等,提出各级荷载作用下桩身位移响应的计算方法;基于Matlab开发平台编制单桩在竖向荷载作用下Q-S曲线和抗拔系数的计算程序,通过与现场试验数据对比验证了本文计算方法的可靠性.研究结果表明:单桩的抗拔系数随着桩土平均模量比的增大而增大,但其增长速率逐渐减小;随着长径比的增大,单桩的抗拔系数线性减小.随着桩土平均模量比的增大,抗拔系数受长径比的影响逐渐减小,当桩土平均模量比为6000时,抗拔系数几乎不随长径比的改变而变化.     

新冠病毒肺炎疫情下的船员权益保障问题

2019与2020年交替之际,一场突如其来的新冠肺炎疫情却悄然出动,迅速蔓延。疫情引起了党中央的高度重视,国家采取了史无前例的严格防控措施,打响了前所未有的、全国军民人人投身的战"疫"。疫情也引起了国际社会的严重关注.     

锌铝镁镀层钢板化学转化膜耐蚀性能研究

采用扫描电子显微镜(SEM)、能谱分析仪(EDS)研究了锌铝镁镀层钢板合金的化学转化膜形貌和元素组成。以热镀锌钢板和冷轧钢板作为比较对象,通过电化学工作站、中性盐雾试验箱对3种合金的腐蚀行为进行对比研究。结果表明,锌铝镁镀层钢板化学转化膜结晶整体呈现为长条针状,结晶排布致密,平均晶粒尺寸约为4μm,膜重达到了3.1 g/m²。锌铝镁镀层钢板的化学转化膜中Al、Mg元素含量高于热镀锌钢板和冷轧钢板。相比而言,锌铝镁镀层钢板化学转化膜的自腐蚀电位最高,为-0.889 V,腐蚀电流和腐蚀速率均最低,分别为26.94μA和2.338×10^-3μA/cm²。在经中性盐雾腐蚀200 h后,锌铝镁镀层钢板基材腐蚀程度最小,说明锌铝镁镀层钢板的耐蚀性能优于热镀锌钢板和冷轧钢板。     

The effect of information overload on the intention of consumers to adopt electric vehicles

Transportation - To encourage the pro-electric vehicle (EV) behavioral intentions of consumers, EV manufacturers should make a significant commitment to EV-related information and devise strategic...     

Experimental research on dynamic responses characteristics and influence laws of gear transmission-propulsion system under gear excitation北大核心CSCD

［Objective］In order to study the dynamic response characteristics and influence laws of a marine gear transmission-propulsion system, a series of bench tests is carried out.［Methods］First, a biaxial gear transmission-propulsion system test bench including a cross connection gear is built. Experiments to test the acceleration response of the gearbox body and propulsion shaft system are then carried out, and the influence of speed, driving mode, axial static thrust, axial dynamic excitation force from the propeller and other factors on the dynamic response characteristics of the system are compared and analyzed. ［Results］The experimental results show that the transmission law of the vibration acceleration response of the gear transmission-propulsion system is mainly at the meshing frequency and its multipliers, as well as peaks in the low frequency band of 30–80 Hz under certain working conditions. ［Conclusion］This study can provide technical support for the vibration and noise reduction design of gear transmission-propulsion systems. © 2022 Journal of Clinical Hepatology. All rights reserved.     

Evaluating impacts of coastal flooding on the transportation system using an activity-based travel demand model: a case study in Miami-Dade County,FL

Transportation - Recent climatic disasters have shown the vulnerability of transportation infrastructures against natural hazards. To understand the risk of coastal hazards on urban travel...