强变形工艺对2519A铝合金组织与性能的影响

通过硬度测试、拉伸性能测试、透射电镜观察等分析手段研究了不同强变形工艺下2519A铝合金的力学性能与微观组织。结果表明,经50%的冷轧变形和165 ℃人工时效后,2519A合金的力学性能明显提高,其抗拉强度、屈服强度和伸长率分别为522 MPa、468 MPa和8.5%。而在冷变形前添加165 ℃×2 h预时效处理,合金的力学性能进一步提高,其抗拉强度、屈服强度和伸长率分别达到535 MPa、497 MPa和8%。预时效处理可以提高合金中θ′相的密度,使析出相分布更加均匀,有助于提高合金的力学性能。     

退火工艺对激光选区熔化成形Ti6Al4V合金组织及室温力学性能的影响

以Ti6Al4V球形粉末为原料,利用激光选区熔化成形方法制备了Ti6Al4V合金试样,采用光学显微镜、扫描电镜及力学性能测试等手段,研究了退火工艺对Ti6Al4V合金室温力学性能及组织的影响规律。结果表明: SLM成形沉积态Ti6Al4V合金室温抗拉强度超过1200 MPa,而平均断后伸长率仅为4.0%;在650 ℃下进行真空退火处理,合金的抗拉强度仍保持在1200 MPa左右,规定塑性延伸强度R_p0.2高于1150 MPa,但试样的断后伸长率<10%;而在750及800 ℃下进行真空退火处理,合金试样的抗拉强度降至1100 MPa左右,规定塑性延伸强度高于1050 MPa,伸长率达到甚至超过10%,材料的综合强韧性得到明显提升。随着真空退火加热温度和保温时间的增加,SLM成形Ti6Al4V合金原始β晶界逐渐变模糊,晶粒趋向于等轴化。与此同时,快速冷却转变的α′针状马氏体未出现明显地粗化。     

Advanced Functional Materials Constructed from Pillar[n]arenes

Pillar[n]arenes are new generation of supramolecular macrocyclic host, which exhibit excellent host−guest recognition properties. In the last decade, functional materials constructed from pillar[n]arenes have been attracted more and more attention and displayed outstanding characteristics, such as stimuli-responsiveness, self-healing and adaptability. In this mini-review, we provide a survey of the pillar[n]arene-based literatures covering light-harvesting systems, functional hydrogels, and solid materials. It is anticipated that more and more pillar[n]arenes-based advanced materials with multi-functional properties will appear in the near future.     

渐变刚度板簧式轻卡悬架阻尼参数仿真设计

为了有效提高渐变刚度钢板弹簧式轻型卡车的乘坐舒适性,根据弹簧受力与刚度和变形之间的关系,利用等频原理,建立了渐变刚度钢板弹簧力学特性解析计算模型,并利用钢板弹簧加载-卸载试验对所建立的模型的正确性进行了验证。基于1/2车辆行驶振动模型,利用MATLAB的Simulink工具箱,建立了考虑渐变刚度钢板弹簧力学特性的轻卡行驶振动仿真分析模型。最后,以人体振动舒适性最佳为目标,利用多岛遗传算法,建立了轻卡悬架系统阻尼参数仿真设计方法,并利用实车试验对所建立的轻卡悬架系统阻尼参数仿真设计方法的正确性进行了验证。上述研究为渐变刚度钢板弹簧式轻卡悬架系统参数的设计提供了有效参考。     

Cover Image

The cover image is based on the Research Article Observer‐Based Cooperative Distributed Fault‐tolerant Model Predictive Control with Imperfect Network Communication and Asynchronous Measurements by Guannan Xiao and Fei Liu, https://doi.org/10.1002/rnc.4994 .

     

Remote Sensing Image Registration Based on Improved KAZE and BRIEF Descriptor

Machine Intelligence Research - Remote sensing image registration is still a challenging task owing to the significant influence of nonlinear differences between remote sensing images. To solve...     

基于智能电表大数据的异常用电检测

异常或欺诈造成的非技术性电力损失是电力公司损失的主要源头之一。智能电表的广泛使用，使得运用大数据方法实现对非技术性电力损失的有效检测成为可能。提出了一种使用监督学习进行非技术损失检测的方法。该方法基于智能仪表记录的所有信息（耗电量、异常警报等）结合辅助数据库所提供的有关每个智能电表的地理位置和技术参数的附加信息，使用最优的机器算法来深入分析用电客户的用电行为，生成异常用电客户列表。通过现场检查的结果表明，该方法能够较为准确地识别智能电网中所存在异常用电客户。     

Study on Spatial-Temporal Evolution of Residential Differentiation in Shanghai from an Employee Perspective

Against a background of deepened globalization, the socio-spatial distribution characteristics of the employed population are one of the important perspectives that reflect the impact of globalization on urban social space. Based on data of the population census of Shanghai in 2000 and 2010, using location quotient and index of dissimilarity, this paper analyzes the residential differentiation evolution in Shanghai from 2000 to 2010. The results show that except the high-end service industry, the residential differentiation of the employees in the other three types of industries has intensified but is not serious. In addition, the proportion of employees in high-end service industry within the Middle Ring has increased, while that of employees in the middle-and low-end service industry beyond the Middle Ring has increased, which further proves that globalization has an increasingly obvious impact on the socio-spatial differentiation in Shanghai. However, the adjustment in spatial development made by the Shanghai municipal government in response to globalization makes the socio-spatial evolution of Shanghai greatly different from the suburbanization of social elites in the West.