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排序方式: 共有88条查询结果,搜索用时 12 毫秒
1.
Guan Lei Yang Xiangyu Li Yu Shi Changliang Yan Dejun Huang Jiayong Zhang Lai-Chang 《Journal of Applied Electrochemistry》2021,51(11):1619-1633
Journal of Applied Electrochemistry - In this work, the electrochemical corrosion behaviours of selective laser melted (SLMed) and wrought Ti6Al4V alloys in acid fluoride-containing artificial... 相似文献
2.
采用光纤激光器开展了碳钢板表面锈蚀层激光清洗研究,通过白光干涉仪、光学显微镜、拉曼光谱仪等研究了激光扫描速度对锈蚀层去除质量的影响。研究表明,当激光扫描速度小于2 000 mm/s时,因光斑搭接率高,热累积效应强,试样表面出现基材熔化重凝现象,同时试样表面发生二次氧化,生成了复杂的铁的氧化物膜层,此时试样表面粗糙度最小。当激光扫描速度增加到3000 mm/s时,试样表面锈蚀层去除干净,露出金属基底本身色泽,基材表面二次氧化减弱。当线速度继续增加时,因光斑搭接率低,锈蚀层吸收的激光能量少,仅有部分锈蚀被去除,试样表面开始出现残留锈蚀层,且随着线速度的增加,残留锈蚀层和试样表面粗糙度增加。通过调节扫描速度可以获得较好的除锈效果,工艺优化后,激光功率为120 W时,除锈效率达到1.5 m2/h。 相似文献
3.
为了研究不同水火成形温度对10CrNiCu钢组织及性能的影响,在标准水火成形工艺评定试板上进行了不同温度水火成形试验,每种温度采用三次重复下火试验。工艺试验结果显示,10CrNiCu钢经历678~983 ℃水火成形后,显微组织仍为铁素体与珠光体双相组织;随着水火成形温度升高,晶粒逐渐长大,且铁素体呈双峰分布,珠光体出现偏析和定向分布;随着水火成形温度升高,10CrNiCu钢的抗拉强度有所升高,而屈服强度、冲击功和硬度略有下降;当水火成形温度高于856 ℃时,10CrNiCu钢的焰道边缘处吸收冲击功与硬度均有所下降,且焰道边缘处附近硬度低于母材,最大下降幅度为18HV10,但均满足相关规范要求。研究表明,980 ℃水火成形后10CrNiCu钢仍有良好的服役性能,可以根据现场变形量的需求,选择合适的水火成形温度。 相似文献
4.
《Ceramics International》2023,49(15):24670-24680
Graphene, the thinnest 2-dimensional atomic material, is successively used as a composite material has it significantly improves optical, thermal, mechanical and electrical properties. Neodymium being a strong paramagnetic substance is capable of storing large amount of magnetic energy because of their greater number of unpaired electrons in their electron orbital structure. This paper focuses on the influence of graphene on the structural, optical and magnetic properties of rare earth neodymium (Nd) doped TiO2 nanoparticles. Nd doped TiO2 nanoparticles are deposited on reduced graphene oxide (rGO) sheets forming the nanocomposites by hydrothermal treatment. The nano size, structure and phase of the composites are analysed by X-ray diffraction and Raman spectra. Dispersion of pure TiO2 and Nd/TiO2 nanoparticles on the rGO sheets is studied with FESEM and HRTEM micrographs alongside the elemental composition confirmed by EDAX. Increased surface area and pore size analysis is revealed by BET isotherms and BJH data. Absorption edges are blue shifted owing to particle size and experimental conditions. PL and EPR spectra confirm the presence of paramagnetic defect centres in the nanocomposites. The M − H hysteresis curves of the composites reveal the ferromagnetic behaviour at room temperature. 相似文献
5.
Metro shield construction will inevitably cause changes in the stress and strain state of the surrounding soil, resulting in stratum deformation and surface settlement (SS), which will seriously endanger the safety of nearby buildings, roads and underground pipe networks. Therefore, in the design and construction stage, optimizing the shield construction parameters (SCP) is the key to reducing the SS rate and increasing the safe driving speed (DS). However, optimization of existing SCP are challenged by the need to construct a unified multiobjective model for optimization that are efficient, convenient, and widely applicable. This paper innovatively proposes a hybrid intelligence framework that combines random forest (RF) and non-dominant classification genetic algorithm II (NSGA-II), which overcomes the shortcomings of time-consuming and high cost for the establishment and verification of traditional prediction models. First, RF is used to rank the importance of 10 influencing factors, and the nonlinear mapping relationship between the main SCP and the two objectives is constructed as the fitness function of the NSGA-II algorithm. Second, a multiobjective optimization framework for RF-NSGA-II is established, based on which the optimal Pareto front is calculated, and reasonable optimized control ranges for the SCP are obtained. Finally, a case study in the Wuhan Rail Transit Line 6 project is examined. The results show that the SS is reduced by 12.5% and the DS is increased by 2.5% with the proposed framework. Meanwhile, the prediction results are compared with the back-propagation neural network (BPNN), support vector machine (SVM), and gradient boosting decision tree (GBDT). The findings indicate that the RF-NSGA-II framework can not only meet the requirements of SS and DS calculation, but also used as a support tool for real-time optimization and control of SCP. 相似文献
6.
Operating construction equipment for extended periods of time may lead to mental fatigue and, as a result, an increased risk of human error-related accidents and jeopardized health problems for the operators. Therefore, to limit the risk of accidents and protect operators' wellbeing, their mental fatigue must be monitored reliably and in real time. Recently, many invasive technologies have been employed to alleviate this problem, but they entail the wearing of physical sensors, which may instigate irritation and discomfort. This study proposes a non-invasive mental fatigue monitoring method using geometric measurements of their facial features that does not require the operators to wear sensors on their body. The study further validates the proposed method by comparing it with wearable electroencephalography (EEG) technology to establish its ecological validity for construction equipment operators. To serve the purpose, a one-hour excavator operation by sixteen construction equipment operators was conducted on a construction site. Ground truth, brain activity using wearable EEG, and geometric measurements of facial features were extracted and analyzed at the baseline and every 20 min for one hour. A considerable temporal variation was found in the reported metrics (eye aspect ratio, eye distance, mouth aspect ratio, face area, and head motion) and were significantly correlated with ground truth and EEG metric. Furthermore, the brain visualization pattern obtained from EEG was also associated with the variations in the facial features. The findings of the study reveal that construction equipment operators’ mental fatigue can be monitored non-invasively using geometrical measurements of facial features. 相似文献
7.
The development of immersive virtual reality (IVR) applications for design reviews is a major trend in the design field. While many different applications have been developed, there is little consensus on the functionalities necessary for these applications. This paper proposes a classification scheme for IVR functionalities related to design reviews (DRs), combining conceptual-to-empirical and empirical-to-conceptual strategies. The classification scheme consists of eight class categories (Input, Representation, Navigation, Manipulation, Collaboration, Edit, Creation, and Output), 22 class subcategories, and 55 classes. The classification scheme has been validated by analysing several commercial IVR applications for DRs. As part of the classification scheme development, Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was utilised to review 70 articles that develop IVR applications for DRs. The results from systematic literature reviews suggest the development of solutions that integrate several class categories, are better connected to current design workflows, include various design information, support a DR planning cycle, and support distributed work. The proposed classification scheme helps to orient the future development of IVR applications for DRs and provides a framework to systematically accumulate evidence on the effect of such applications on DRs. 相似文献
8.
9.
采用不同搅拌头转速,研究了搅拌头转速对4 mm厚2205双相不锈钢板材搅拌摩擦焊接头组织及性能的影响. 结果表明,当焊接速度为50 mm/min时,搅拌头转速在600 ~ 800 r/min的范围内,均可获得表面成形良好且内部无缺陷的接头.接头搅拌区在动态再结晶的作用下组织得到细化,硬度值较高,热影响区在焊接热作用下组织粗化,硬度值较低.整个接头的铁素体含量在50% ~ 60%范围内,且随着转速的升高搅拌区的铁素体含量有所增加. 当转速为600 r/min时,接头的抗拉强度达到最大824 MPa,为母材的97.3%,断裂位置为接头的热影响区. 相似文献
10.
针对100 mm超厚板TC4钛合金电子束焊接接头,采用慢应变速率拉伸方法评价接头在人造海水中的应力腐蚀敏感性,分析接头的显微组织和断口形貌,对接头的腐蚀机制进行研究. 结果表明,室温条件下应变速率为ε=1×10-6 s-1时,母材在海水中未表现出应力腐蚀敏感性;焊缝上部、中部和下部具有轻微应力腐蚀敏感性. 焊缝在海水中发生阳极溶解,产生氢吸附,导致裂纹的萌生. 同时氢扩散诱导α'相界及α'相内发生位错塞积,进而使裂纹在更低的应力水平下发生扩展. 相似文献