Zhenpeng Wu, Vanliem Nguyen, Zhihong Zhang and Liangcai Zeng
The stepped topography of the friction pairs mainly causes the fluid film thickness to change in the direction of motion. In this region, there have very few topographical design…
Abstract
Purpose
The stepped topography of the friction pairs mainly causes the fluid film thickness to change in the direction of motion. In this region, there have very few topographical design methods for continuous or non-linear distribution of the fluid film. The purpose of this study is to analyze the effect of the curved surface on the performance of the liquid film.
Design/methodology/approach
First, a numerical simulation is used to solve the optimal bearing capacity and friction coefficient of the liquid film under the condition of the minimum film thickness. Then, the curved surface described by the sinusoidal curve equation is applied in the transitional region of maximum and minimum film thickness. The bearing capacity and the friction coefficient of the liquid film are respectively simulated and compared in the same condition of the minimum film thickness.
Findings
The research results show that the liquid film using the curved surface transition model, the optimal bearing capacity is significantly increased by 32 per cent while the optimal friction coefficient is clearly reduced by 38 per cent in comparison with using stepped surface model.
Originality/value
The friction pair with curved transition enables better lubrication performance of the liquid film and better adaptability under unstable conditions.
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Zhenpeng Wu, Xianzhong Ding, Liangcai Zeng, Xiaolan Chen and Kuisheng Chen
This paper aims to use the method of curve splicing to combine the slip zone and the no-slip zone to further improve the lubrication performance of the liquid film. The…
Abstract
Purpose
This paper aims to use the method of curve splicing to combine the slip zone and the no-slip zone to further improve the lubrication performance of the liquid film. The combination of the slip zone and the no-slip zone of an existing heterogeneous surface is still a single line stitching method so that a very large residual space at the surface of the friction pairs remains present, necessitating further improvement of the joining scheme between the slip zone and the no-slip zone in heterogeneous surfaces.
Design/methodology/approach
A set of discrete sinusoids is used as the splicing track for both the slip zone and the no-slip zone, the starting point and amplitude of the curve are introduced as the simulation variables and the effects of these variables on the bearing capacity and friction coefficient of the liquid film are comprehensively analyzed.
Findings
The results show that the method of selecting the sinusoidal curve as the slip zone and the no-slip zone trajectory, which is based on the existing method of linear stitching, can further enhance the bearing capacity and reduce the friction coefficient of the liquid film.
Originality/value
This method can further enhance the bearing capacity and reduce the friction coefficient of the liquid film.
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Vanliem Nguyen, Zhenpeng Wu and Vanquynh Le
To improve the lubrication and tribology performance (LTP) of the crankpin bearing, this paper aims to propose the optimization of the crankpin bearing parameters considering…
Abstract
Purpose
To improve the lubrication and tribology performance (LTP) of the crankpin bearing, this paper aims to propose the optimization of the crankpin bearing parameters considering effect of the high-speed dynamic load and micro asperity contact.
Design/methodology/approach
A numerical simulation method combined by the slider-crank-mechanism dynamic and lubrication models is applied to solve the dynamic and lubrication equations of crankpin bearing. These equations are then computed via an algorithm program written in Matlab software. The contact force (Wac) in the asperity contact region, friction force (Ff) and friction coefficient (μ) of crankpin bearing are chosen as objective functions. The original parameters and experimental data of the engine are used for the simulation to enhance the reliability of the research results. The parameters are then optimized to obtain the minimum values of Wac, Ff and μ.
Findings
The research results show that the LTP is significantly improved with optimized parameters. Particularly, the maximum values of Wac and Ff are greatly decreased by 27 and 32%, respectively.
Originality/value
Reducing the width, radius and surface roughness and increasing the radial clearance of crankpin bearing can improve better the LTP.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2020-0072/
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Zhongkai Shen, Shaojun Li, Zhenpeng Wu, Bowen Dong, Wenyan Luo and Liangcai Zeng
This study aims to investigate the effects of irregular groove textures on the friction and wear performance of sliding contact surfaces. These textures possess multiple depths…
Abstract
Purpose
This study aims to investigate the effects of irregular groove textures on the friction and wear performance of sliding contact surfaces. These textures possess multiple depths and asymmetrical features. To optimize the irregular groove texture structure of the sliding contact surface, an adaptive genetic algorithm was used for research and optimization purposes.
Design/methodology/approach
Using adaptive genetic algorithm as an optimization tool, numerical simulations were conducted on surface textures by establishing a dimensionless form of the Reynolds equation and setting appropriate boundary conditions. An adaptive genetic algorithm program in MATLAB was established. Genetic iterative methods were used to calculate the optimal texture structure. Genetic individuals were selected through fitness comparison. The depth of the groove texture is gradually adjusted through genetic crossover, mutation, and mutation operations. The optimal groove structure was ultimately obtained by comparing the bearing capacity and pressure of different generations of micro-convex bodies.
Findings
After about 100 generations of iteration, the distribution of grooved textures became relatively stable, and after about 320 generations, the depth and distribution of groove textures reached their optimal structure. At this stage, irregular texture structures can support more loads by forming oil films. Compared with regular textures, the friction coefficient of irregular textures decreased by nearly 47.01%, while the carrying capacity of lubricating oil films increased by 54.57%. The research results show that irregular texture structures have better lubrication characteristics and can effectively improve the friction performance of component surfaces.
Originality/value
Surface textures can enhance the friction and lubrication performance of metal surfaces, improving the mechanical performance and lifespan of components. However, surface texture processing is challenging, as it often requires multiple experimental comparisons to determine the optimal texture structure, resulting in high trial-and-error costs. By using an adaptive genetic algorithm as an optimization tool, the optimal surface groove structure can be obtained through simulation and modeling, effectively saving costs in the process.
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Hui Zeng, Hao Xu and Zhenpeng Yu
People’s economic behaviors are often embedded in their social networks. Based on social embeddedness theory, this study investigates how customers’ social network embeddedness…
Abstract
Purpose
People’s economic behaviors are often embedded in their social networks. Based on social embeddedness theory, this study investigates how customers’ social network embeddedness (structural and relational embeddedness) affects their online referral intentions through four studies.
Design/methodology/approach
This study adopted a vignette experimental design and used both offline and online channels to collect data. The respondents were undergraduate students and consumers, covering different age groups and occupation types. We used the ANOVA and bootstrap methods of SPSS to conduct data processing and hypothesis testing.
Findings
We found that when fewer (vs more) people in a customer’s social network participated in reward referral programs (RRPs), the customer’s online referral intention was also lower because of higher perceived social costs and lower perceived control. However, when the tie strength, reciprocity and normative influence between customers and people who have participated in RRPs were high, customers’ online referral intention also increased, ignoring the influence of participants’ network size. In these relationships, perceived social costs and perceived control played important mediating roles.
Practical implications
The results provide practical implications for enterprises to develop efficient RRPs in the context of the increasing popularity of the mobile Internet and intelligent terminals.
Originality/value
This study offers insights into the influence mechanism of social network embeddedness on referral likelihood, contributing to the field of RRPs and social embeddedness theory.
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Zhenpeng He, Wenqin Gong, Weisong Xie, Guichang Zhang and Zhenyu Hong
Piston ring dynamic problem plays an important role in the lubricant characteristics of a reciprocating engine, which lead to engine wear and the increased consumption of…
Abstract
Purpose
Piston ring dynamic problem plays an important role in the lubricant characteristics of a reciprocating engine, which lead to engine wear and the increased consumption of lubricating oil. A cavitation analysis of the piston ring lubrication with two-dimensional Reynolds equation has rarely been reported owing to the complex working condition. The purpose of this study is to establish a precise model that can provide guidance for the design of the piston ring.
Design/methodology/approach
In this paper, a cavitation model and its effect on the piston ring lubrication was studied in a simulation program based on the mass-conserving theory which is solved by means of the Newton–Raphson method. In this study, some models such as mixed lubrication, asperity contact, blow-by/blow-back flow and cavitation have been coupled with the lubrication model.
Findings
The established model has been compared with the traditional model that deals with cavitation by using the Reynolds boundary condition algorithm. The cavitation zone, pressure distribution and density distribution between the piston ring and the cylinder have also been predicted. Studies of the changing trend for the pressure distribution and the cavitation zone at few typical crank angles have been listed to illustrate the cavitation changing rule. The analysis of the results indicates that the developed simulation model can adequately illustrate the lubrication problem of the piston ring system. All the analyses will provide guidance for the oil film rupture and the reformation process.
Originality/value
A two-dimensional cavitation model based on the mass-conserving theory has been built. The cavitation-forming and -developing process for the piston ring–liner lubrication has been studied. Non-cavitation occurs in the vicinity of top dead center and bottom dead center. The non-cavitation period will be longer in the vicinity of 360° of crank angle. The density distribution in the cavitation zone can be obtained.
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Zhenpeng Luo, Einar Marnburg and Rob Law
This study aims to investigate the mediating role of collective identity in the relations among transformational leadership, procedural justice and employee organizational…
Abstract
Purpose
This study aims to investigate the mediating role of collective identity in the relations among transformational leadership, procedural justice and employee organizational commitment.
Design/methodology/approach
An empirical survey was conducted in 43 hotels in mainland China with 585 valid responses. In addition to descriptive statistics and the test of the presence of common method bias, a confirmatory factor analysis was conducted to test the validities and reliabilities of the variables; structural equation modeling and hierarchical regression analyses were conducted to test causal relations and the mediating effects of collective identity.
Findings
Results show that transformational leadership and procedural justice are good predictors of employee collective identity and organizational commitment. In addition to a strong impact on employee commitment, collective identity partially mediates the effects of transformational leadership and procedural justice on employee commitment.
Research limitations/implications
This study is restricted to China’s hotel supervisors; therefore, caution should be taken when applying the findings to other sectors, regions and higher levels of leaders.
Practical implications
Findings of this study offer managerial insights for hotel supervisors to exercise transformational leadership and procedural justice to improve employee collective identity, which drives organizational commitment.
Originality/value
As an important concept, studies on the role of self-identity are limited in management and the field of leadership. This study tested the role of collective identity in leadership and organizational commitment in the context of Chinese culture, highlighting its theoretical and practical implications.
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This study aims to explain the state-of-the-art machine learning models that are used in the intrusion detection problem for human-being understandable and study the relationship…
Abstract
Purpose
This study aims to explain the state-of-the-art machine learning models that are used in the intrusion detection problem for human-being understandable and study the relationship between the explainability and the performance of the models.
Design/methodology/approach
The authors study a recent intrusion data set collected from real-world scenarios and use state-of-the-art machine learning algorithms to detect the intrusion. The authors apply several novel techniques to explain the models, then evaluate manually the explanation. The authors then compare the performance of model post- and prior-explainability-based feature selection.
Findings
The authors confirm our hypothesis above and claim that by forcing the explainability, the model becomes more robust, requires less computational power but achieves a better predictive performance.
Originality/value
The authors draw our conclusions based on their own research and experimental works.