Digital twin-based assembly data management and process traceability for complex products

Complex products such as satellites, missiles, and aircraft typically have demanding requirements for dynamic data management and process traceability. The assembly process for these complex products involves high complexity, strong dynamics, many uncertainties, and frequent rework and repair, especially in the model development stage. Achieving assembly data management and process traceability for complex products has always been a challenge. A recently proposed solution involves one-to-one mapping of the corresponding physical entity, also known as the digital twin method. This paper proposes a digital twin-based assembly data management and process traceability approach for complex products. First, the dynamic evolutionary process of complex product assembly data was analyzed from three dimensions: granularity, period and version. Then, a framework of digital twin-based assembly data management and process traceability for complex products was constructed. Some core techniques are: 1) workflow-based product assembly data organization and version management; 2) synchronous modeling of the product assembly process based on digital twin; and 3) hierarchical management and traceability of product assembly data based on digital twin. On this basis, an algorithm flowchart for generating a product assembly data package was created, which includes product assembly data management, assembly process traceability, and generation of a product assembly data package. Furthermore, the Digital Twin-based Assembly Process Management and Control System (DT-APMCS) was designed to verify the efficiency of the proposed approach. Some aerospace-related assembly enterprises are currently using DT-APMCS and achieving satisfactory results. Finally, a summary of our work is given, and the future research work is also discussed.     

Qualification of an ultrasonic flow meter as a transfer standard for measurements at Reynolds numbers up to 4×106 between NMIJ and PTB

The quality of any laboratory intercomparison depends to a large extent on the performance of the used flow meter. To find a flow meter that is capable of reaching a reproducibility better than 0.05% requires bounding all involved influence quantities down to the required level. The present paper describes the efforts performed while qualifying a time-of-flight ultrasonic flow meter as a transfer standard. It was determined that the most relevant influence quantity besides the flow profile within the bulk flow is the effect caused by the transducer pockets in the meter body. By taking advantage of a specially designed window chamber, it was possible to determine the magnitude of the errors introduced by the transducer pockets and to define, based on the findings, a procedure to perform a bilateral comparison between the hot water calibration facilities of the Physikalisch-Technische Bundesanstalt and the National Institute of Advanced Industrial Science and Technology. The results of the bilateral comparison are presented.     

基于锶元素含量及其稳定同位素比值的库尔勒香梨产地鉴别

开展锶（Sr）元素含量及其稳定同位素比值鉴别库尔勒香梨产地的可行性研究，明确新疆库尔勒香梨87Sr/86Sr同位素特征值，为库尔勒香梨产地真实性鉴别提供科学依据。以陕西红香酥梨和甘肃香梨作为对照，借助电感耦合等离子质谱分析新疆库尔勒香梨与对照样品及其对应果园土壤的Sr元素含量，采用多接收器电感耦合等离子质谱分析库尔勒香梨果皮与果肉87Sr/86Sr同位素比值。通过方差分析比较不同产地、不同年际土壤及果实中Sr元素含量的差异，探讨果实与土壤Sr元素含量的相关关系，以及不同产地果实87Sr/86Sr同位素比值与Sr元素含量的分布特征。结果表明：新疆、甘肃、陕西共3 个产地梨园土壤Sr含量存在显著差异（P＜0.05），不同年际间梨园土壤Sr含量不存在显著差异。果皮与果肉Sr元素含量存在极显著相关（P＜0.01），但二者与土壤Sr元素含量均不存在显著相关。3 个产地梨果肉/果皮Sr含量不存在显著差异。3 个产地87Sr/86Sr同位素比值存在显著差异（P＜0.05）。果皮Sr同位素更适合用于库尔勒香梨产地鉴别研究。本实验通过稳定同位素技术为库尔勒香梨产地鉴别提供参考。     

关节型机械手的结构创新设计

分析了关节型机械手的总体要求,进行了机构设计,确定了驱动方式,研究并解决了全关节型机械手关节结构设计的关键技术,重点介绍了机身、肩关节、肘关节、小臂、手腕及抓手关节的结构创新设计思路和方法。     

基坑回弹监测的方法及应用

该文介绍了基坑回弹监测的测点布设、标志形式、常用的观测方式及其精度、资料整理与分析等的基本工作方法,最后,通过一个具体的实例加以说明。     

地下建筑物防渗堵漏工法

简述了地下建筑物渗漏的处理,应选用合适的防渗漏材料和施工方法,才能达到预期的效果。     

带局部结构转换层的不规则建筑结构设计

介绍了带局部结构转换层不规则建筑结构设计中的结构布置、结构分析、转换层设计及有关构造措施,可供同类工程的结构设计参考。     

我国西部小城镇给水与污水处理技术需求分析

我国西部地区由于地域辽阔，自然地理环境复杂多样，经济发展水平落后，其城镇给水和污水处理工艺不能简单照搬国外或国内发达地区现有的成熟技术。在对西部30余个小城镇实地调研的基础上，结合西部小城镇社会经济状况和各地区自然环境特点，分析了西部小城镇对给水和污水处理设施的技术需求，并针对自然环境特征不同的地区提出了相对较为适宜的城镇给水和污水处理技术。     

工程中常用的几种钢筋混凝土柱的加固方法

介绍了工程中常用的几种钢筋混凝土柱的加固方法的特点，探讨了各种加固方法的设计计算公式、构造及施工要求，可供实际加固工程参考应用。     

磷渣粉对混凝土物理性能影响的研究

通过磷渣粉对混凝土物理性能影响的实验研究，探讨了磷渣粉对水泥净浆需水量、水泥净浆和混凝土凝结时间、混凝土流动性、高性能混凝土抗压强度等的影响情况，从而为磷渣作为混凝土掺合料提供了可行性依据。