聚(3-羟基丁酸酯-3-羟基戊酸酯)/聚碳酸亚丙酯复合支架的构建与表征

分别采用反应性和非反应性熔融共混方法结合粒子沥滤技术以及碱处理技术构建不同质量比的聚(3-羟基丁酸酯-3-羟基戊酸酯)(PHBV)/聚碳酸亚丙酯(PPC)复合支架,通过表征支架的表面形态、孔隙率大小和体外降解性能,发现反应性共混法可显著改善支架的相容性和界面粘接。非反应性熔融共混法构建的支架孔隙率高于反应性共混法构建的复合支架。随着PPC含量的升高,复合支架的孔隙率升高。当PHBV/PPC质量比达50/50时,支架在PBS缓冲液中降解最快,反应性共混法构建的支架亲水性高于非反应性共混法,碱处理技术可显著改善复合支架的亲水性。这对功能重建的体内研究和临床实践具有潜在的理论价值和应用前景。     

液压驱动机械臂的设计与关节驱动分析

设计了一种新型六自由度串联机械臂,并提出了基于液压摆动缸的机械臂驱动关节控制方法。机械臂驱动关节由两个输出轴相互垂直的液压摆动缸提供动能,驱动形式采用闭环液压驱动,闭环控制系统由上位机、信号控制卡、电位传感器等组成。建立了该机械臂的三维模型,应用D-H方法对其进行了运动学建模和正向运动学分析,最后对基于液压摆动缸的机械臂驱动关节控制方法进行了实验分析,得出了机械臂关节运行速度与脉宽调制(PWM)调速占空比的关系,根据实验结果得出了相应的运动曲线关系,为串联机械臂位置控制、运动路径控制研究提供了基础。     

光学经纬仪一测回水平方向标准偏差的测量不确定度评定

本文采用多齿分度台方法对DJ2级光学经纬仪一测回水平方向标准偏差进行测量,分析了测量结果不确定度的主要来源,并对测量值的不确定度进行评定,最后提出了用多齿分度台方法进行检定时应注意的问题。     

Mechanical and Reaction Properties of Al/TiH2/PTFE under Quasi‐Static Compression

TiH₂ is introduced into Al/PTFE reaction system for the first time. In order to study the mechanical and reaction properties of Al/TiH₂/PTFE composites, five kinds of mixtures with different TiH₂ contents and the contrasting TiH₂/PTFE mixture are prepared. The true stress–strain curves and reaction phenomena are recorded during the quasi‐static compression experiments; The reaction residues are analyzed with XRD to understand the reaction mechanism. The results show that the introduction of TiH₂ can significantly influence the strength of the composites; With the increasing of TiH₂ content, the mechanical strength is firstly increase and then decrease; When the content is the same, the reinforcing effect of TiH₂ particles on PTFE matrix is greater than that of Al. Violent reaction are observed in the four Al/TiH₂/PTFE composites with the content of TiH₂ below 20%, but not in TiH₂/PTFE. Furthermore, compared with Al/PTFE material, special flames are found during the reaction of composites with TiH₂, which become even more obvious with the increasing of TiH₂ content. The material reaction mechanism denotes that the high temperature of the crack tip result in the reaction of Al and PTFE, which activates TiH₂ to release hydrogen and generate TiC, resulting TiH₂ to fully release its energy.