Aibin Zhu, Hongling Wu, Yulei Yang and Shengli He
Because of the various geometric descriptions of different bearing types, performance calculation of journal bearing is complicated, and is difficult in traditional model. This…
Abstract
Purpose
Because of the various geometric descriptions of different bearing types, performance calculation of journal bearing is complicated, and is difficult in traditional model. This paper aims to simplify the calculation of the journal bearing performance, and to reduce the workload.
Design/methodology/approach
On the basis of previous research, a general performance calculation model of journal bearing is proposed in this paper. Eccentricity ratio and attitude angle of axis to each pad are calculated by coordinates of spindle center and each pad center by establishing the unified coordinate system. The surface deformation of journal bearing is taken into consideration, and a correction value is added to the dimensionless oil film thickness.
Findings
The performance calculation results of various fix-pad and tilting-pad journal bearings match the results of the existing references very well, revealing the validity of the model. The general model can greatly reduce programming workload, and increase adaptability to different bearings.
Originality/value
Geometric descriptions of both fix-pad and tilting-pad journal bearings are unified in this model, which can be applied to both standard and non-standard journal bearings with different preload ratios. In addition, due to the unification of different bearings types, this model is more conducive to performance comparison among different bearing types, and promotes the development of new structural forms for journal bearings.
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Haitao Wang, Jiayu Shen and Da Gao
Abutment damage in liquefied ground is an important form of seismic damage of bridge structure. This paper aims to further research the effect of beam restriction on seismic…
Abstract
Purpose
Abutment damage in liquefied ground is an important form of seismic damage of bridge structure. This paper aims to further research the effect of beam restriction on seismic damage mode of abutment in liquefied ground.
Design/methodology/approach
Based on the investigation of the seismic damage of Shengli Bridge in Tangshan earthquake, the finite element software dynamic effective stress analysis for ground (UWLC) is used to simulate the seismic damage of Shengli Bridge, and the results were compared with the actual seismic damage results. Then, the influences of the horizontal binding force of the beam, the liquefaction layer thickness, the top weight of the abutment, the peak acceleration, the liquefaction layer buried depth and the type of the foundation soil on the abutment seismic damage model are studied.
Findings
The results show that numerical simulation results are consistent with the actual seismic damage, and it is feasible to use UWLC software to simulate seismic damage. The results show that the seismic failure mode of the gravity abutment in liquefied ground is slip–rotation coupling type, not single slip type or rotation type. The large deformation of abutment bottom layer, horizontal binding force of the beam and post-stage soil pressure are the main reasons for abutment rotation or even destruction.
Research limitations/implications
A series of basic assumptions are used in the calculation process in this paper. The gravity abutment is defined as the elastic body and neglects its local deformation. The soil layer is a homogeneous isotropic. The consolidation process and the drainage boundary problem are not considered in the calculation process. Therefore, the paper may have some limitations.
Originality/value
To further research the seismic damage mode and influencing factors of abutment in liquefied ground, in this paper, based on the investigation of the seismic damage of Shengli Bridge in Tangshan earthquake, the finite element software UWLC is used to simulate the seismic damage of Shengli Bridge, and the results were compared with the actual seismic damage results. The seismic damage mode and influencing factors of gravity abutment in liquefied ground have been studied.
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Xiaoyu Chen, Alton Y.K. Chua and Shengli Deng
As an increasing number of users have acquired information across the web and mobile platforms for social question and answering (Q&A), it is of interest to explore whether there…
Abstract
Purpose
As an increasing number of users have acquired information across the web and mobile platforms for social question and answering (Q&A), it is of interest to explore whether there are differences in social Q&A usages between the two platforms. The purpose of this paper is to compare web and mobile platforms of a social Q&A service from the user’s perspective in terms of three dimensions, namely, demographics, individual-based constructs, and information-based constructs.
Design/methodology/approach
Because Zhihu.com is one of the most popular social Q&A sites in China, the authors used online questionnaires to investigate its users’ perceptions of these three dimensions. From January to March 2016, the authors obtained 278 valid responses in total through snowball and convenient sampling. Collected data are analyzed through descriptive statistics and inferential statistics.
Findings
The results indicate that there exist significant differences between web users and mobile users on Zhihu.com in terms of gender, affinity, and information seeking. More specifically, compared to the male users, more female users rely on the mobile platform to access the information service; mobile users perceive higher affinity with Zhihu.com than web users; and mobile users perceive higher information-seeking intention than web users do.
Originality/value
Regarding the theoretical aspect, this study proposes a conceptual framework for comparison between the web and mobile platforms of social Q&A from the user’s perspective. Regarding the practical aspect, the comparative results of this study could give social Q&A service providers useful information about users’ differences between web and mobile platforms of social Q&A services.
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Yuan Peng, Shengli Hou, Weifeng Zhai, Xiaofeng Yang, Hao He and Xiaotong Guo
This study aims to provide guidance for the reliability of electronic packaging. The reliability of solder joints at extremely temperature thermal shock is critical for electronic…
Abstract
Purpose
This study aims to provide guidance for the reliability of electronic packaging. The reliability of solder joints at extremely temperature thermal shock is critical for electronic equipment operating in the field of deep space exploration. In this study, the Sn3.0Ag0.5Cu (SAC305)/Cu solder joints were prepared and thermally shocked with temperatures ranging from −110°C to 110°C, to investigate the effects of extreme temperature thermal shock on the microstructural evolution and property deterioration of the solder joints.
Design/methodology/approach
The interfacial intermetallic compound (IMC) stress gradient was calculated through thermal stress theory, mechanism of voids/cracks initiation was clarified, and prediction of the service life was analyzed with the energy-based model.
Findings
It is found that the Ag3Sn, IMC and cracks/voids had evolved significantly with the increase in the cycle period. The microstructure of the IMC changed from short rod-like morphology to scallop shape, the voids in the Cu3Sn IMC layer continued to increase and integrate, forming larger diameter voids, etc. In addition, the shear strength of SAC305/Cu solder joints decreased gradually with the increase in thermal shock cycles, the fracture mode changes from ductile fracture mode to ductile-brittle mixed fracture mode after 500 cycles. The characteristic lifetime of the SAC305/Cu solder joints under the action of extreme thermal shock is about 1427.86 cycles.
Originality/value
This work provides guidance for the reliability of the solder joints at extremely temperature thermal shock.
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Shengli Tian, Xiaoan Chen, Tianchi Chen and Ye He
The purpose of this study is to investigate accurate and effective experimental methods for measuring the frictional loss of bearings (FLB) in mechanical systems and to measure…
Abstract
Purpose
The purpose of this study is to investigate accurate and effective experimental methods for measuring the frictional loss of bearings (FLB) in mechanical systems and to measure the effect of various operating parameters on the frictional loss of high-speed mechanical systems.
Design/methodology/approach
Two novel methods were studied in this paper to measure the FLB: the free-deceleration method and the energy-balance method. A special high-speed motorised spindle and a friction loss test rig were designed and built to measure the effects of rotational speed, lubrication, preload and operating temperature on the FLB.
Findings
The experimental results showed that the frictional torque of bearings increases initially but then decreases with an increase in rotational speed. Similarly, the FLB decreases initially and then increases with an increase in temperature because of the influence of the viscosity–temperature relationship of the lubricant and the thermomechanical coupling factor. The optimal lubricant flow was determined, and the effectiveness of a novel preload online adjusting device was verified through experiments.
Originality/value
The research results of this paper provide the basis and methods for the measurement, reduction and prediction of the FLB in mechanical systems.
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Yuting Jiang, Shengli Deng, Hongxiu Li and Yong Liu
The purposes of this paper are to (1) explore how personality traits pertaining to the dominance influence steadiness compliance model manifest themselves in terms of user…
Abstract
Purpose
The purposes of this paper are to (1) explore how personality traits pertaining to the dominance influence steadiness compliance model manifest themselves in terms of user interaction behavior on social media and (2) examine whether social interaction data on social media platforms can predict user personality.
Design/methodology/approach
Social interaction data was collected from 198 users of Sina Weibo, a popular social media platform in China. Their personality traits were also measured via questionnaire. Machine learning techniques were applied to predict the personality traits based on the social interaction data.
Findings
The results demonstrated that the proposed classifiers had high prediction accuracy, indicating that our approach is reliable and can be used with social interaction data on social media platforms to predict user personality. “Reposting,” “being reposted,” “commenting” and “being commented on” were found to be the key interaction features that reflected Weibo users' personalities, whereas “liking” was not found to be a key feature.
Originality/value
The findings of this study are expected to enrich personality prediction research based on social media data and to provide insights into the potential of employing social media data for the purpose of personality prediction in the context of the Weibo social media platform in China.
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Haiping Zhao, Shengli Deng, Yong Liu, Sudi Xia, Eric Tze Kuan Lim and Chee-Wee Tan
Drawing on the Health Belief Model (HBM), this study aims to investigate the roles of health beliefs (i.e. perceived susceptibility, perceived severity, perceived benefits…
Abstract
Purpose
Drawing on the Health Belief Model (HBM), this study aims to investigate the roles of health beliefs (i.e. perceived susceptibility, perceived severity, perceived benefits, perceived barriers, health self-efficacy and cues to action) in promoting college students’ smartphone avoidance intention.
Design/methodology/approach
Empirical data were collected through a cross-sectional survey questionnaire administered to 4,670 student smartphone users at a large university located in Central China. Further, a two-step Structural Equation Modeling was conducted using AMOS 22.0 software to test the hypothesized relationships in the research model.
Findings
Analytical results indicate that (1) perceived susceptibility, perceived severity, perceived benefits and health self-efficacy positively influence users’ smartphone avoidance intention; (2) perceived barriers negatively influence smartphone avoidance intention, while (3) cues to action reinforce the relationships between perceived susceptibility/perceived benefits and smartphone avoidance intention, but attenuate the relationships between perceived barriers/health self-efficacy and smartphone avoidance intention.
Research limitations/implications
This study demonstrates that HBM is invaluable in explaining and promoting users’ smartphone avoidance intention, thereby extending extant literature on both HBM and smartphone avoidance.
Originality/value
Research on smartphone avoidance is still in a nascent stage. This study contributes to the field by offering a fresh theoretical lens for pursuing this line of inquiry together with robust empirical evidence.
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The purpose of this paper is to explore the motivations underpinning recent evolving corporate social and environmental reporting (CSER) among enterprises in China through the…
Abstract
Purpose
The purpose of this paper is to explore the motivations underpinning recent evolving corporate social and environmental reporting (CSER) among enterprises in China through the lenses of senior managers.
Design/methodology/approach
Using the interpretive tenets of engagement research, semi-structured in-depth interviews were adopted to explore the perceptions of senior managers from 21 large companies in various industries. The aim is to make sense of the emerging CSER phenomenon occurring in the field through engagement, observation and penetrating interviews.
Findings
The findings identify the main enablers driving CSER in China as: regulations and government influence; management awareness; benefits to company image; peer pressure/reporting by peers and public pressure on controversial companies. Guided by a system-based theoretical framework in terms of motivations for CSER, this study offers insights into the effectiveness of using widely adopted Western-based theoretical approaches in a Chinese context where companies operate against a different socio-economic, political, regulatory and cultural backdrop.
Research limitations/implications
The deep-rooted face (Mianzi) culture has the potential to influence managers to portray a positive image about their companies and themselves.
Originality/value
This engagement-based study is one of the few initiatives exploring managerial perceptions of CSER in China that adds to the scant literature pertaining to rich “emic” data in accounting, encompassing cultural influence by applying systems-oriented theoretical framework. The stimulus for CSER identified are useful for regulators and organizations to better comprehend how to set effective policies that promote CSER and fit the distinctive institutional characteristics of China.
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The purpose of this paper is to investigate regime-switching and single-regime GARCH models for the extreme risk forecast of the developed and the emerging crude oil markets.
Abstract
Purpose
The purpose of this paper is to investigate regime-switching and single-regime GARCH models for the extreme risk forecast of the developed and the emerging crude oil markets.
Design/methodology/approach
The regime-switching GARCH-type models and their single-regime counterparts are used in risk forecast of crude oil.
Findings
The author finds that the regime-switching GARCH-type models are suitable for the developed and the emerging crude oil markets in that they effectively measure the extreme risk of crude oil in different cases. Meanwhile, the model with switching regimes captures dynamic structures in financial markets, and these models are just only better than the corresponding single-regime in terms of long position risk forecast, instead of short position. That is, it just outperforms the single-regime on the downside risk forecast.
Originality/value
This study comprehensively compares risk forecast of crude oil in different situations through the competitive models. The obtained findings have strong implications to investors and policymakers for selecting a suitable model to forecast extreme risk of crude oil when they are faced with portfolio selection, asset allocation and risk management.