Failure load prediction and optimisation for adhesively bonded joints enabled by deep learning and fruit fly optimisation

Adhesively bonded joints have been extensively employed in the aeronautical and automotive industries to join thin-layer materials for developing lightweight components. To strengthen the structural integrity of joints, it is critical to estimate and improve joint failure loads effectually. To accomplish the aforementioned purpose, this paper presents a novel deep neural network (DNN) model-enabled approach, and a single lap joint (SLJ) design is used to support research development and validation. The approach is innovative in the following aspects: (i) the DNN model is reinforced with a transfer learning (TL) mechanism to realise an adaptive prediction on a new SLJ design, and the requirement to re-create new training samples and re-train the DNN model from scratch for the design can be alleviated; (ii) a fruit fly optimisation (FFO) algorithm featured with the parallel computing capability is incorporated into the approach to efficiently optimise joint parameters based on joint failure load predictions. Case studies were developed to validate the effectiveness of the approach. Experimental results demonstrate that, with this approach, the number of datasets and the computational time required to re-train the DNN model for a new SLJ design were significantly reduced by 92.00% and 99.57% respectively, and the joint failure load was substantially increased by 9.96%.     

Mechanism of heterogeneous distribution of Cr-containing dispersoids in DC casting 7475 aluminum alloy

The actual effective partition coefficients of Mg and Cr in a cross-section of a dendrite arm in a direct-chill (DC)-casting ingot of 7475 aluminum alloy are obtained. Meanwhile, by analyzing the microstructure, the mechanism of the heterogeneous distribution of E (Al₁₈Mg₃Cr₂) dispersoids in this DC ingot is revealed. The results show that the actual effective partition coefficients of Mg and Cr are 0.650 and 1.392, respectively, and they describe the heterogeneous distributions of Mg and Cr along the direction of radius of the cross-section of the dendrite arm of the alloy. After homogenization treatment at 470 °C for 24 h, Mg diffuses uniformly, but Cr hardly diffuses. Both the concentrations of Mg and Cr and the sites of heterogeneous nucleation in the alloy are the determinants of the formation of E dispersoids simultaneously. The heat treatment at 250 °C for 72 h provides a large number of the sites of heterogeneous nucleation of the formation of fine E dispersoids that will be formed in the center of the cross-section during the subsequent heat treatment at higher temperature.     

Specification uncertainty in modeling internet adoption: A developing city case analysis

Internet adoption fosters economic growth and development. Specifying policy control drivers is particularly relevant for developing countries. However, there is no consensus on the most relevant variables. We explored 33.6 million potential models to identify the most important determinants of household internet adoption using stochastic search variable selection and socioeconomic data from Medellín, Colombia. We found that monthly income, the head of household education and voting, and having a computer and cable television at home are the most relevant variables.     

受限空间安全作业管理浅析

受限空间因受作业场所限制,存在的危险因素较多,受限空间安全管理控制措施为:建立许可制,落实责任和措施,做好受限空间作业人员的个体防护,对受限空间作业的安全管理要实行从审批到应急处理全过程的控制。介绍了受限空间的危险特点和事故类型,提出了受限空间作业安全管理的具体措施。     

Enriching Context Information for Entity Linking with Web Data

Journal of Computer Science and Technology - Entity linking (EL) is the task of determining the identity of textual entity mentions given a predefined knowledge base (KB). Plenty of existing...     

Comparative analysis of formaldehyde and toluene sorption on indoor floorings and consequence on Indoor Air Quality

Indoor surfaces may be adsorptive sinks with the potential to change Indoor Air Quality. To estimate this effect, the sorption parameters of formaldehyde and toluene were assessed on five floorings by an experimental method using solid-phase microextraction in an airtight emission cell. Adsorption rate constants ranged from 0.003 to 0.075 m·h⁻¹, desorption rate constants from 0.019 to 0.51 h⁻¹, and the partition coefficient from 0.005 to 3.9 m, and these parameters vary greatly from one volatile organic compound/material couple to another indicating contrasted sorption behaviors. A rubber was identified as a sink of formaldehyde characterized by a very low desorption constant close to 0. For these sorbent floorings identified, the adsorption rates of formaldehyde are from 2 to 4 times higher than those of toluene. Two models were used to evaluate the sink effects of floorings on indoor pollutant concentrations in one room from different realistic conditions. The scenarios tested came to the conclusion that the formaldehyde sorption on one rubber (identified as a sink) has a maximum contribution from 15% to 21% for the conditions of low air exchange rate. For other floorings, the sorption has a minor contribution less than or equal to 5%, regardless of the air exchange rate.     

Influence of expertise on semantic categorization of wine odors

Aromatic characterization is a key element of enhancing one’s knowledge of wine. While several studies have investigated the importance of wine expertise in the ability to perform odor-related sensory tasks, little attention has been paid to the influence of expertise on the semantic categorization of wine odors. To bridge this gap, this study aimed to explore the influence of a subject’s expertise on the semantic representation of wine odors by means of a free sorting task. For this purpose, 156 subjects were recruited. Their level of expertise was measured using a questionnaire and the data analysis revealed four clusters of subjects with a gradual level of expertise. Subjects also performed a sorting task on 96 odor terms. From the number and the size of odor groups formed, as well as the additive tree representation and the consensus partition between the terms for each expertise level, we observed that all subjects, regardless of their experience, had largely the same semantic categorization of wine-odor attributes, which was mainly shaped by the sources of the odorants. It appeared that level of wine expertise played a minor role in creating the semantic representation of wine odors, affecting mainly the knowledge of specialized terms.     

钛表面激光熔覆NiCr-Ag复合涂层结构及空间摩擦学性能研究

利用激光熔覆技术在钛基材表面制备了NiCr-Ag复合涂层。用XRD、SEM和HRTEM分析了涂层的组成和组织结构,利用空间摩擦学系统对复合涂层在三种模拟空间环境(高真空、原子氧和紫外辐照)以及大气环境下的摩擦磨损性能进行了系统的研究。采用SEM和EDS对磨损后复合涂层和对偶钢球的形貌和元素面分布进行了分析,揭示了复合涂层在模拟空间环境及大气环境下摩擦磨损失效机理。结果表明：复合涂层在大气环境条件下的摩擦磨损性能优于在三种模拟空间环境下的摩擦磨损性能；真空下的辐照对复合涂层的摩擦磨损性能有显著的影响,辐照会增加涂层表面氧化；复合涂层在高真空、原子氧和紫外辐照模拟空间环境下的磨损机理为较严重的粘着磨损、磨粒磨损和塑性变形,在大气环境条件下的磨损机理主要为磨粒磨损。     

码垛机器人运动学分析及关节空间轨迹规划研究

以IRB-460工业机器人为研究对象,针对其运动学建模及在笛卡尔空间和关节空间下的轨迹规划方法展开研究并进行对比。对机器人本体进行了机器人运动学分析,利用多项式轨迹插值算法进行了关键点间的轨迹规划,完成了重叠型码垛的作业流程。利用Robotics Toolbox完成了轨迹规划算法仿真,并进行了结果分析。仿真结果表明在关节空间下进行轨迹插补所得的路径点更为优化,所得的轨迹更为满足作业任务,具备合理性。     

遗传算法和模矢法结合的概率积分法参数反演方法

遗传算法在反演概率积分法预计参数时从参数取值范围内的串集开始搜索,并使用弹性策略来维持群体的多样性,使得算法可以跨过局部收敛的障碍,向全局最优解方向进化;但这种概率化的寻优算法存在局部探索能力差、结果不稳定的缺陷,只能获得问题的近似最优解。模矢法是一种降梯度算法,算法局部探索能力强、收敛快;但这种算法对初值选取敏感,初值选择不当易陷入局部极值。本文提出并实现了一种模矢法与遗传算法结合的组合算法:先使用遗传算法求得参数的全局近似最优解,然后将近似最优解作为探索初值,使用模矢法获得参数的稳定、精确最优解。研究结果表明:组合算法反演概率积分法预计参数的精确度高、收敛快、稳定性好,综合性能较遗传算法和模矢法有明显优势。