车门铰链系统与车门下沉刚度的相关性

针对某型车门下沉问题,通过台架试验获得车门、铰链和车身等各单因素下沉量和车门绞链系统整体下沉量,对单因素下沉量与系统整体下沉刚度进行线性拟合分析,得到车门铰链系统各单因素与系统下沉刚度的相关度排序.对前、后车门分别选取相关度较高的单因素进行优化,最终改进方案的仿真和试验结果证明该方案可有效地提升车门下沉刚度.采用定量分析法可快速找出影响下沉刚度的敏感因素,并能够快速生成优化方案,为新车型设计提供参考.     

Toughness and R-curve behaviour of laminated Si3N4/SiCw ceramics

Laminated Si₃N₄/SiC_w ceramics were successfully prepared by tape casting and hot-pressing. Its mechanical properties were measured and the impact resistance was discussed. The toughness of the laminated Si₃N₄/SiC_w ceramics was 13.5 MPa m^1/2, which was almost 1.6 times that of Si₃N₄/SiC_w composite ceramics, namely 8.5 MPa m^1/2. Moreover, the indentation strength of laminated Si₃N₄/SiC_w ceramics was not sensitive to increasing indentation loads and exhibited a rising R-curve behaviour, indicating that the laminated Si₃N₄/SiC_w ceramics had excellent impact resistance. The improved toughness and impact resistance of laminated Si₃N₄/SiC_w ceramics was attributed to the residual stress caused by a thermal expansion coefficient mismatch between the different layers, resulting in crack deflection and bridging of SiC whiskers in the interface layer, thus consuming a large amount of fracture work.     

基于纸喷雾离子化衍生质谱法快速检测PM2.5中的醌污染物

醌类化合物是PM2.5中的一类有害物质。本研究建立了纸喷雾离子化衍生质谱法快速测定PM2.5中的醌类污染物。通过衍生化反应在醌化合物中引入氨基，提高醌在纸喷雾中的离子化效率。随后对衍生化试剂种类、电压、喷雾溶剂种类等反应条件进行优化。在最优实验条件下，采用内标法定量分析1,4-苯醌、甲基对苯醌、1,4-萘醌和1,4-蒽醌，4种化合物均呈现较好的线性关系，其检出限分别为4.49、20.89、0.13、0.17 ng。利用该方法分析PM2.5实际样品中的萘醌和蒽醌，均获得了较好的定性和定量结果。     

浅谈压力铸造的全自动化生产

近年来,国家对制造业的数字化、网络化、智能化越来越重视,特别是《中国制造2025》的发布,更是促进整个制造业向智能制造迈进,铸造行业也应该紧跟步伐。在传统压力铸造行业中压铸机的加料、取件,切边机的上件、下件,加工机床的上件、下件,都是依靠人来完成,大大制约了行业的发展。本文阐述了压力铸造的全自动化生产,为压力铸造行业的转型升级提供借鉴。     

当代青年在新冠肺炎疫情防控中的社会责任担当研究

面对新冠肺炎疫情,多数青年积极进取、富有创造力和责任心,少数青年缺乏应有的担当意识.文章分析了当代青年社会责任感缺失的成因,提出了青年社会责任担当意识养成的举措.     

Thiol-Functionalized Covalent Organic Frameworks as Thermal History Indictor for Temperature and Time History Monitoring

Various products, including foods and pharmaceuticals, are sensitive to temperature fluctuations. Thus, temperature monitoring during production, transportation, and storage is critical. Facile indicators are required to monitor temperature conditions via color changes in real time. This study aimed to prepare and apply thiol-functionalized covalent organic frameworks (COFs) as a novel indicator for monitoring thermal history and temperature abuse. The COFs underwent obvious color changes from bright yellow to purple after exposure to different temperatures for varying durations. The reaction kinetics are analyzed under isothermal conditions, which reveal that the order of reaction rates is k_−20°C < k_4°C < k_20°C < k_35°C < k_55°C. The activation energy (E_a) of the COFs is calculated using the Arrhenius equation as 50.71 kJ moL⁻¹. The COFs are capable of sensitive color changes and offer a broad temperature tracking range, thereby demonstrating their application potential for the monitoring of temperature and time exposure history during production, transportation, and storage. This excellent performance thermal history indicator also shows promise for expanding the application field of COFs.     

用COMSOL实现圆波导中电磁波的可视化

为了直观描述金属圆波导中电磁场复杂的空间分布,本文用Comsol软件对金属圆波导中的TE11模、TE01模、和TM01模的电磁场结构进行动态仿真.将电磁场中的抽象概念形象化、可视化,使学生看清电磁场分布的宏观概况和细节变化,开拓了视野,同时加深了学生对电磁波传播特性的理解.     

双螺旋线圆柱凸轮机构的设计与分析

以应某企业要求设计一款用于机械手臂端部完成螺旋高速往复的机构,介绍了双滚子在螺旋线圆柱凸轮上的应用.采用解析法对机构的受力以及运动进行理论分析.利用NX10.0建模,将模型导入Adams2016输出其运动数据,对解析法结果进行验证.对设计初期得到的滚子与螺旋切槽的接触冲击进行分析,针对双滚子在运作时对螺旋切槽造成冲击大、晃动剧烈、部分零件磨损严重等问题,对圆柱凸轮机构进行优化改进,利用Adams2016软件对滚子的运动进行模拟分析.分析运算后的结果验证了改进后的机构在很大程度上实现了增加双滚子螺旋运动的平稳性能,更好的实现了双滚子与凸轮槽之间的拟合,实现了机构的平稳、高效运行.     

直升机主旋翼离心上限动器损伤解决措施

旋翼作为直升机关键动部件之一,其健康状态直接关系到直升机的安全性与可靠性.针对直升机主旋翼离心上限动器的损伤问题,通过机理分析、运动仿真确定其损伤原因,制定改进措施并通过了试飞验证,对国内直升机技术的发展具有积极促进性作用.