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This paper applies the knowledge-based genetic algorithm to solve the optimization problem in complex products technological processes.

The knowledge-based genetic algorithm (KGA) is defined as a hybrid genetic algorithm (GA) which combined the GA model with the knowledge model. The GA model searches the feasible space of optimization problem based on the “neighborhood search” mechanism. The knowledge model discovers some knowledge from the previous optimization process, and applies the obtained knowledge to guide the subsequent optimization process.

The experimental results suggest that the proposed KGA is feasible and available. The effective integration of GA model and knowledge model has greatly improved the optimization performance of KGA.

The technological innovation of complex products is one of effective approaches to establish the core competitiveness in future. For this reason, the KGA is proposed to the technological processes optimization of complex products.

The purpose of this paper is to establish a chair-side design and production method for a tooth-supported fixed implant guide and to evaluate its accuracy.

Three-dimensional (3D) data of the alveolar ridge, adjacent teeth and antagonistic teeth were acquired from models of the edentulous area of 30 patients. The implant guides were then constructed using self-developed computer-aided design software and chair-side fused deposition modelling 3D-printing and positioned on a dental model. A model scanner was used to acquire 3D data of the positioned implant guides, and the overall error was then evaluated.

The overall error was 0.599 ± 0.146 mm (n = 30). One-way ANOVA revealed no statistical differences among the 30 implant guides. The gap between the occlusal surface of the teeth covering and the tissue surface of the implant guide was measured. The maximum gap after positioning of the implant guide was 0.341 mm (mean, 0.179 ± 0.019 mm). The implanted axes of the printed implant guide and designed guide were compared in terms of overall, lateral and angular error, which were 0.104 ± 0.004 mm, 0.097 ± 0.003 mm, and 2.053° ± 0.017°, respectively.

The results of this study demonstrated that the accuracy of a new chair-side tooth-supported fixed implant guide can satisfy clinical requirements.

To identify the typical multilevel issues in social science, as well as illustrate the theoretical basis, hierarchical models and empirical exemplars of multilevel paradigm.

Hierarchical and multilevel data are extremely common in social systems, but multilevel analysis is constrained by statistical techniques. With the development of social system theory and empirical methods such as hierarchical structure modeling and latent growth modeling, multilevel paradigm can be used to analyze multilevel data. So it is necessary to identify typical multilevel phenomena in social science and discuss multilevel modeling techniques.

This paper identifies four typical multilevel phenomena in social system study: hierarchical and clustered sampling, collective construct research, longitudinal repeated measures, and event history analysis. Hierarchical structure modeling and latent growth modeling are effective multilevel analysis techniques in social science because of their advantages in the integration of social system research.

The quality and availability of multilevel data are the main limitations regarding which model will be applied.

The paper can aid the provision of effective multilevel models to social workers.

This paper provides information on application of multilevel modeling in social science.

This paper aims to study the synergistic lubrication effects of Sn–Ag–Cu and MXene–Ti₃C₂ to improve the tribological properties of M50 bearing steel with microporous channels.

M50 matrix self-lubricating composites (MMSC) were designed and prepared by filling Sn–Ag–Cu and MXene–Ti₃C₂ in the microporous channels of M50 bearing steel. The tribology performance testing of as-prepared samples was executed with a multifunction tribometer. The optimum hole size and lubricant content, as well as self-lubricating mechanism of MMSC, were studied.

The tribological properties of MMSC are strongly dependent on the synergistic lubrication effect of MXene–Ti₃C₂ and Sn–Ag–Cu. When the hole size of microchannel is 1 mm and the content of MXene–Ti₃C₂ in mixed lubricant is 4 wt.%, MMSC shows the lowest friction coefficient and wear rate. The Sn–Ag–Cu and MXene–Ti₃C₂ are extruded from the microporous channels and spread to the friction interface, and a relatively complete lubricating film is formed at the friction interface. Meanwhile, the synergistic lubrication of Sn–Ag–Cu and MXene–Ti₃C₂ can improve the stability of the lubricating film, thus the excellent tribological property of MMSC is obtained.

The results help in deep understanding of the synergistic lubrication effects of Sn–Ag–Cu and MXene–Ti₃C₂ on the tribological properties of M50 bearing steel. This work also provides a useful reference for the tribological design of mechanical components by combining surface texture with solid lubrication.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0381/

This paper aims to predict and evaluate the wear rate of TiAl-2 Wt.% MoO₃ tabular crystals (TMCs) using the Newton interpolation methods.

The friction and wear behaviors of TMC were examined using pin-on-disc apparatus at different times, namely, 1,200, 2,400, 3,600, 4,800 and 6,000 s. The wear rates of five different times as interpolation nodes were measured and calculated by electron probe microanalysis (EMPA) and field emission electron microscope (FESEM). Then, the prediction formula of wear rate was constructed using the Newton interpolation method. The accuracy of the prediction formula and the relationship with friction layer and worn surface are verified for evaluating the reliability of the prediction formula.

The prediction formula shows a similar variation trend of TMC as the experimental results, indicating that the prediction formula can forecast the wear rate and working condition of TMC. Moreover, the microstructures of friction layer and worn surface also have a strong impact on the prediction formulas.

The prediction formulas of the Newton interpolation polynomial can be adopted to predict working longevity in the mechanical components, which can guide the practical engineering application in industrial fields.

Microblog has become an important tool of social marketing since 2010. Compared with traditional blog, microblog has several distinctive features, such as ease of use, viral transmission, high interactivity and real-time communication. Microblog provides a communication platform for companies and consumers; however, it challenges companies’ consumer-brand relationship management. The purpose of this paper is to investigate the influencing mechanism of microblog interaction tactics on consumer-brand relationship.

Based on grounded theory, 66 representative companies’ posts on Weibo are collected, with 1,395 company posts and 5,959 following posts. An influence mechanism model of company microblog interaction tactics on consumer-brand relationship is proposed, then the saturation level of this mechanism is tested.

Results show that: first, companies adopt two types of tactics in microblog interaction: social interaction and task-oriented interaction; second, microblog interaction arises consumers’ emotional response and cognition toward specific brand and eventually influences consumer-brand relationship. Consumers’ emotional response includes pleasure and arousal, brand cognition includes perceived quality, perceived relatedness with companies and brand resonance; third, the influence mechanism differs among different consumer knowledge level, industry and brand awareness.

This study provides insight into the use of microblog interaction tactics. Companies may cross-use social interaction and task-oriented interaction tactics to enhance consumer-brand relationship. Companies need to produce microblog content based on the interests of consumers and further establish and improve fan feedback mechanism.

This paper constructs a model of the influence of company microblog interaction tactics on consumers. This study finds that co-creation activities initiated by companies are the new tactics to attract consumers on microblog. The finding adds new knowledge to the literature of company consumer interaction and provides a theoretical basis for the practice of microblog marketing.

The purpose of this paper is to investigate the influence of binder effect on tribological behavior of brake friction composite materials: a case study of phenolic resin modified by N-Methylaniline.

Four different friction materials have been fabricated by varying modified phenolic resin content. The samples were prepared by the conventional powder metallurgy methods following ball milling, mixing, pre-forming, hot pressing and post-curing processes. Thermogravimetric analysis was used to determination of the degradation mechanism of organic components and study of thermal stability of the samples. A friction test was carried out in dry conditions using a vertical tribometer. Analysis of worn surfaces was performed using a scanning electron microscope.

The experimental results revealed that the sample containing 25 Wt.% phenolic resin has good mechanical and thermal properties with stable friction characteristics.

This paper presents the effect of N-methylaniline modified phenolic resin on friction composites to improve tribological performance by its thermal properties.