Haiming Dai, Guo Xiang, Jiaxu Wang, Juan Guo, Cheng Wang and Hang Jia
The purpose of this study is to numerically investigate the time-varying mixed lubrication performance of microgroove journal-thrust coupled bearing (MJTCB) under nonlinear…
Abstract
Purpose
The purpose of this study is to numerically investigate the time-varying mixed lubrication performance of microgroove journal-thrust coupled bearing (MJTCB) under nonlinear excitation.
Design/methodology/approach
A three degree of freedom (3-DOF) dynamic model of the rotor coupling with the transient mixed lubrication behavior is established. Based on numerical predictions, the role of the microgroove on the time-varying mixed lubrication performance of MJTCB is identified. The effects of the microgroove depth, microgroove shape and external load on the time-varying mixed lubrication performance of MJTCB are also studied.
Findings
Numerical results show that the effect of the coupling hydrodynamic on the time-varying mixed lubrication performance of the coupled bearing is strengthen with the increasing of microgroove depth. Furthermore, it is found that the optimal microgroove shape for the thrust bearing, arc or rectangle, highly depends on the microgroove depth. Finally, the contact performance of the thrust bearing is slightly affected by the radial external load.
Originality/value
This study is expected to achieve a better understanding of the time-varying mixed lubrication performance of MJTCB under nonlinear excitations.
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Guo Xiang Guo Xiang, Yanfeng Han, Renxiang Chen, Jiaxu Wang Jiaxu Wang and Ni Xiaokang
This paper aims to present a numerical model to investigate the mixed lubrication performances of journal-thrust coupled bearings (or coupled bearings).
Abstract
Purpose
This paper aims to present a numerical model to investigate the mixed lubrication performances of journal-thrust coupled bearings (or coupled bearings).
Design/methodology/approach
The coupled hydrodynamic effect (or coupled effect) between the journal and the thrust bearing is considered by ensuring the continuity of the hydrodynamic pressure and the flow field at the common boundary. The mixed lubrication performances of the coupled bearing are comparatively studied for the cases of considering and not considering coupled effect.
Findings
The simulated results show that the hydrodynamic pressure distributions for both the journal and thrust bearing are modified due to the coupled effect. The decreased load capacity of the journal bearing and the increased load capacity of the thrust bearing can be observed when the coupled effect is considered. And the coupled effect can facilitate in reducing the asperity contact load for both the journal and thrust bearing. Additionally, the interaction between the mixed lubrication behaviors, especially for the friction coefficient, of the journal and the thrust bearing is significant in the elastohydrodynamic lubrication regime, while it becomes weak in the mixed lubrication regime.
Originality/value
The developed model can reveal the mutual effects of the mixed lubrication behavior between the journal and the thrust bearing.
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Cheng-Ta Yang, Her-Tyan Yeh, Bing-Chang Chen and Guo-Xiang Jian
Extensive efforts have been conducted on the real-time strategy (RTS) games. The purpose of this paper is the specific artificial intelligence (AI) challenges posed by RTS games;…
Abstract
Purpose
Extensive efforts have been conducted on the real-time strategy (RTS) games. The purpose of this paper is the specific artificial intelligence (AI) challenges posed by RTS games; non-player character (NPC) is started out by collecting game-map resources to build up defenses and attack forces, to upgrade combat deployment.
Design/methodology/approach
The authors used weak AI fuzzy theory as the foundation for tunable development. With the fuzzy theory, the AI was more humanistic in its judgment process.
Findings
Well-developed AIs have been used brilliantly in various aspects in RTS games, especially in those developed by large production teams. For small production teams, how to develop an AI system in less time and at a lower cost is extremely important.
Research limitations/implication
This study aimed to develop a system using player unit threat levels for NPC deployment and arrangement so that the further strategy would be adopted for NPCs in response to player actions.
Originality/value
The RTS games would become more challenging for players to play.
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Yanfeng Han, Lei Yin, Guo Xiang, Guangwu Zhou, Haizhou Chen and Xiaolin Zheng
The tribological behavior, i.e. friction coefficient and wear rate, and vibration characteristics of the water-lubricated bearing was investigated. The water-lubricated bearing is…
Abstract
Purpose
The tribological behavior, i.e. friction coefficient and wear rate, and vibration characteristics of the water-lubricated bearing was investigated. The water-lubricated bearing is made of three different materials, i.e. polyether-ether-ketone (PEEK), polyimide (PI) and nitrile-butadiene rubber (NBR).
Design/methodology/approach
The tribological behavior was investigated experimentally on a specially designed test rig. Three vibration sensors were used to record the vibration of the bearing.
Findings
The results indicated that the variation of friction coefficient with rotation speed agrees well with the trend of Stribeck curve. The tested friction coefficient of rubber bearing is higher than that of the other two bearings whether it is in the state of mixed-lubrication or hydrodynamic lubrication, and which causing a larger wear rate in rubber bearing. The PEEK bearing exhibits the best tribological properties due to it has smaller friction coefficient and wear rate. However, it can be found that the rubber bearing gives the minimum vibration acceleration, which means that the rubber bearing has the most potential to improve the stability of water-lubricated bearing rotor system.
Originality/value
In this study, a group of experiment studies conducted on a specially designed test rig. The comprehensive performance, including friction coefficient, vibration acceleration and wear rate, of water-lubricated bearing with three different materials, i.e. PEEK, PI and NBR, was compared systematically. The experiment research may offer a reference for the selection of material in water-lubricated bearing in specific operating conditions.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0447/
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Guo Xiang, Yijia Wang, Cheng Wang and Zhongliang Lv
In this study, the dynamic characteristics of the water-lubricated rubber bearing considering asperity contact are numerically studied, including water-film stiffness and damping…
Abstract
Purpose
In this study, the dynamic characteristics of the water-lubricated rubber bearing considering asperity contact are numerically studied, including water-film stiffness and damping coefficients and plastic-elastic contact stiffness coefficient.
Design/methodology/approach
The Kogut-Etsion elastic-plastic contact model is applied to calculate the contact stiffness coefficient at the bearing-bush interface and the perturbed method is used to calculate the stiffness and damping coefficients of water-film. In addition, the rubber deformation is determined by the finite element method (FEM) during the simulation. Parametric studies are conducted to assess the effects of the radial clearance, rubber thickness and elastic modulus on the dynamic characteristic of water-lubricated rubber bearing.
Findings
Numerical results indicate that stiffness and damping coefficients of water film and the contact stiffness of asperity are increased with the decreasing of the radial clearance and the dynamic coefficients are less sensitive to the rubber thickness compared with the elastic modulus of rubber. Furthermore, due to the existed groove, a sudden change of the water film direct stiffness and damping coefficients is observed when the eccentricity ratio ranges from 0.6 to 1.0.
Originality/value
It is expected this study can provide more information to establish a dynamic equation of water-lubricated rubber bearings exposed to mixed lubrication conditions.
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Yanglei Jia, Keke Zheng, Xinglong Liu and Xiang Guo
The highly competitive atmosphere of the short video platforms has increased their similarity, while users possess remarkably diverse preferences, complicating the improvement of…
Abstract
Purpose
The highly competitive atmosphere of the short video platforms has increased their similarity, while users possess remarkably diverse preferences, complicating the improvement of user stickiness. To address this issue, this research investigates the effects of different factors, including perceived usefulness, ease, enjoyment, interactivity, and social influence, on user stickiness.
Design/methodology/approach
To estimate these effects, it employs partial least square-structural equation modeling (PLS-SEM), technology acceptance model (TAM3) and theory of planned behavior (TPB) to analyze data collected from a questionnaire distributed among online users between July 20, 2023 and October 28, 2023.
Findings
The results indicate that all the studied factors have positive and significant effects on user stickiness. In addition, they confirmed the considerable effect of flow experience on the relationships between these factors and user stickiness, particularly in interactivity.
Originality/value
These findings show the short video platforms how to manage different factors effectively in stickiness to increase their uniqueness among competitors, attracting and keeping different users by covering their diverse preferences.
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Rick L. Brattin, Randall S. Sexton, Rebekah E. Austin, Xiang Guo, Erica M. Scarmeas and Michelle J. Hulett
This study aims to identify how objective indicators of destination country risk differentiate business study abroad programs from those in other academic disciplines.
Abstract
Purpose
This study aims to identify how objective indicators of destination country risk differentiate business study abroad programs from those in other academic disciplines.
Design/methodology/approach
The authors trained a neural network model on six years of student-initiated inquiries about study abroad programs at a large US university. The model classified business versus nonbusiness study abroad programs using objective measures of destination country risk as the primary inputs.
Findings
The model correctly classifies business and nonbusiness study abroad programs with over 70% accuracy. Business programs were found to be 20% less likely to include destinations where the Centers for Disease Control and Prevention recommend nonroutine vaccinations and favor countries with higher Global Peace Index scores.
Practical implications
These results underscore the need to consider destination country risk in the design and administration of study abroad programs. An understanding of student preferences for lower risk destinations can contribute to improved planning, execution and student experiences in these programs.
Social implications
Better planning and management of study abroad programs based on understanding of destination country risk can lead to enhanced student safety and experiences.
Originality/value
This study offers a unique perspective on understanding study abroad programs by focusing on objective measures of destination country risk rather than risk perceptions. It also is, to the best of the authors’ knowledge, the first to use a neural network to classify study abroad programs as business versus nonbusiness using objective measures of country-specify risk indicators.
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Ma Juan, Chen Jian‐jun, Zhang Jian‐guo and Jiang Tao
The uncertainty of the interval variable is represented by interval factor, and the interval variable is described as its mean value multiplied by its interval factor. Based on…
Abstract
The uncertainty of the interval variable is represented by interval factor, and the interval variable is described as its mean value multiplied by its interval factor. Based on interval arithmetic rules, an analytical method of interval finite element for uncertain structures but not probabilistic structure or fuzzy structure is presented by combining the interval analysis with finite element method. The static analysis of truss with interval parameters under interval load is studied and the expressions of structural interval displacement response and stress response are deduced. The influences of uncertainty of one of structural parameters or load on the displacement and stress of the structure are examined through examples and some significant conclusions are obtained.
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Xiang‐Yu Guo, Zhi‐Gang Yu, Todd Schmit, Brian Henehan and Dan Li
The purpose of this paper is to evaluate the level of new socialist countryside (NSC) construction among different provinces in China. China prioritized a NSC reform policy in…
Abstract
Purpose
The purpose of this paper is to evaluate the level of new socialist countryside (NSC) construction among different provinces in China. China prioritized a NSC reform policy in 2005 to address the growing disparities in incomes and living standards between rural and urban populations. These policies are evaluated to measure the extent of effective reform concerning farmer, agricultural, and rural economic development.
Design/methodology/approach
An index system is developed and factor analysis is performed to describe the relative contributions of economic reform. Aggregate index scores are computed to rank provincial progress.
Findings
Rankings indicate the progression of rural economic reform is moderate, at best, and mostly isolated to well‐developed eastern provinces. Reform growth is also uneven across similarly rural provinces, indicating a need for continued attention in these poorer areas.
Originality/value
Continued applications of the index and scoring procedure developed here will provide useful insights as time progresses and reform efforts continue.
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The goal of this chapter is to respond to the theoretical inquiries by scholars who are interested in how the public–private partnership (PPP) models adapt to China’s context…
Abstract
The goal of this chapter is to respond to the theoretical inquiries by scholars who are interested in how the public–private partnership (PPP) models adapt to China’s context where political power dictates economic strategies. We also want to provide suggestions to policy designers who aim to promote a sustainable investment environment for domestic and international investors. We review the literature that explains the upside and downside of PPP projects in contemporary China. (1) We classify the trajectory of PPP evolution into four phases, i.e., emergence, growth, recession and revival. (2) We note that private companies take a disadvantageous position in the partnership compared with governments and state-owned enterprises because of a lack of specialized legislation, unequal competition between private companies and state-owned enterprises and the opposition from the civic society. (3) We identify political risks as the most influential risks. Political risks also lead to the misallocation of other risks between public and private parties that contributes to the high failure rate of China’s PPP projects. Based on these findings, we recommend governments to draft specialized legislation, stabilize the political environment and provide favourable subsidies to local governments to limit the risks involved in PPP projects. We also advise private enterprises and state-owned enterprises to focus on negotiating over task and risk division with governments when they make decisions to participate in PPP projects. This full review of studies on PPP development in China provides reliable recommendations to scholars, governments and enterprises.