基于有限元法的聚碳酸酯激光焊接性能研究

为了揭示焊接参量对焊接质量的影响机理,优化焊接工艺参量,利用超景深显微镜和拉伸试验机对不同功率、焊接速率和材料厚度参量下的焊接强度进行了观察和测试。采用ABAQUS建立3维轴对称物理模型,对焊接过程中的温度分布进行了有限元模拟,并通过正交试验获得了各参量对焊接质量的影响规律。结果表明,激光功率是影响焊接强度的首要因素,其次是焊接速率,材料厚度影响最小;焊接过程中焊接温度越高,焊缝的宽度越大,可能导致熔池材料分解,焊缝中的气泡增多,影响焊接强度。     

基于逆向工程与快速成型的假体设计和制造

在传统的义耳制作中,通常采用人工雕刻自身软肋骨来完成,其精度及制作效率取决于雕刻师的技巧、经验及审美水平。文章介绍了一种基于激光扫描和快速成形技术制作假体的方法。以义耳设计和制造为例,采用激光扫描仪获取耳朵的轮廓数据,并通过逆向软件生成曲面,最后在快速成型系统中加工出模型。研究结果表明,该集成制造方法可以快速制作出准确逼真的造型,从而为手术的规划提供直接的参考。     

45钢送丝激光熔覆成型基础工艺

45钢送丝激光熔覆成型工艺将通过单道及搭接熔覆实验进行研究.送丝方向和角度、送丝速度、激光扫描速度和功率对熔覆质量和效率的影响将首先得到研究.搭接实验旨在研究45钢的最佳搭接率.熔道微观硬度和微观组织的研究旨在证明基于送丝技术的激光熔覆成型可得到致密的金属组织,为后续激光熔覆修复和激光熔覆快速成型打下基础.     

45钢送丝激光熔覆温度场及应力场模拟

针对激光熔覆过程的特点,基于有限元分析软件ANSYS,对45钢送丝激光熔覆过程的温度场和应力场进行三维数值动态模拟.建模时采用实体单元和表面单元相结合的方式,采用参数化设计划分网格,施加热源载荷,设定初始条件和基本边界条件,对流边界条件进行求解.分析了激光熔覆过程中温度场在工件上的分布规律,揭示了整个时间历程上应力强度的变化规律,为提高激光熔覆质量提供了理论依据.     

The dynamic correction of collimation errors of CT slicing pictures

To eliminate the motion artifacts of CT images caused by patient motions and other related errors, two kinds of correctors (A type and U type) are proposed to monitor the scanning process and correct the motion artifacts of the original images via reverse geometrical transformation such as reverse scaling, moving, rotating and offsetting. The results confirm that the correction method with any of the correctors can improve the accuracy and reliability of CT images, which facilitates in eliminating or decreasing the motion artifacts and correcting other static errors and image processing errors. This provides a foundation for the 3D reconstruction and accurate fabrication of the customized implants.     

激光透射焊接塑料实验研究

为了研究焊接参数(如激光功率、焊接速度)对激光透射焊接塑料强度以及显微结构的影响,采用YAG激光器(功率为300 W,波长为1064 nm)进行聚碳酸酯(PC)材料的激光透射焊接。然后,利用万能材料试验机对焊接后的试件进行拉伸测试,最后利用光学显微镜对焊缝进行微观结构观察,测量焊缝宽度,分析焊缝质量。结果表明,透明PC塑料厚度在1~3.5 mm之间,透射率变化不明显。随着激光能量输入从0.27 J/mm增加到1 J/mm,焊接强度增加;当激光能量输入超过1 J/mm后,焊接强度开始减小。当透明塑料厚度为3.5 mm、激光功率为40 W、焊接速度为40 mm/s时,拉断力可达到峰值1.3 kN。为了提高焊接强度,应严格控制激光能量输入。     

A bispecific immunotoxin (DTAT13) targeting human IL-13 receptor (IL-13R) and urokinase-type plasminogen activator receptor (uPAR) in a mouse xenograft model

A bispecific immunotoxin (IT) called DTAT13 was synthesized in order to target simultaneously the urokinase-type plasminogen activator receptor (uPAR)-expressing tumor neovasculature and IL-13 receptor expressing glioblastoma cells with the goal of intratumoral administration for brain tumors. The recombinant hybrid was created using the non-internalizing N-terminal fragment (ATF) of uPA and the IL-13 molecule for binding plus the catalytic and translocation portion of diphtheria toxin (DT) for killing. The 71 kDa protein was highly selective for human glioblastoma in vitro showing no loss on binding compared with DTAT and DTIL13 controls. In vivo, DTAT13 caused the regression of small tumors when administered at 10 micro g/day given on a five-dose schedule every other day. DTAT13 was able to target both overexpressed uPAR and the vasculature, as demonstrated by its ability to kill HUVEC cells. Also, mortality studies indicated that DTAT13 was less toxic than DTAT or DTIL13. These findings indicate that bispecific IT may allow treatment of a broader subset of antigenically diverse patients while simultaneously reducing the exposure to toxin required than if two separate agents were employed.     

LRFM成型系统工艺参数的基本研究

简要介绍了快速成型设备的开发体系,从工艺参数的角度分析LRFM成型设备各参数对快速成型加工过程的影响,并从软件技术上提出了相应的解决方案。