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Article
Publication date: 19 May 2022

Wenhua Guo, Xinmin Hong and Chunxia Chen

This paper aims to study the influence of aerodynamics force of trains passing each other on the dynamic response of vehicle bridge coupling system based on numerical simulation…

565

Abstract

Purpose

This paper aims to study the influence of aerodynamics force of trains passing each other on the dynamic response of vehicle bridge coupling system based on numerical simulation and multi-body dynamics and put forward the speed threshold for safe running of train under different crosswind speeds.

Design/methodology/approach

The computational fluid dynamics method is adopted to simulate the aerodynamic force in the whole process of train passing each other by using dynamic grid technology. The dynamic model of vehicle-bridge coupling system is established considering the effects of aerodynamic force of train passing each other under crosswind, the dynamic response of train intersection on the bridge under crosswind is computed and the running safety of the train is evaluated.

Findings

The aerodynamic force of trains' intersection has little effects on the derailment factor, lateral wheel-rail force and vertical acceleration of train, but it increases the offload factor of train and significantly increases the lateral acceleration of train. The crosswind has a significant effect on increasing the derailment factor, lateral wheel-rail force and offload factor of train. The offload factor of train is the key factor to control the threshold of train speed. The impact of the aerodynamic force of trains' intersection on running safety cannot be ignored. When the extreme values of crosswind wind speed are 15 m·s−1, 20 m·s−1 and 25 m·s−1, respectively, the corresponding speed thresholds for safe running of train are 350 km·h−1, 275 km·h−1 and 200 km·h−1, respectively.

Originality/value

The research can provide a more precise numerical method to study the running safety of high-speed trains under the aerodynamic effect of trains passing each other on bridge in crosswind.

Details

Railway Sciences, vol. 1 no. 2
Type: Research Article
ISSN: 2755-0907

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Article
Publication date: 17 June 2020

Ningning Wu, Hong Guo, Shuai Yang and Shaolin Zhang

This paper aims to study the influence of thermal effect on the performance for a high-speed conical hybrid bearing including stability and minimum oil film thickness.

145

Abstract

Purpose

This paper aims to study the influence of thermal effect on the performance for a high-speed conical hybrid bearing including stability and minimum oil film thickness.

Design/methodology/approach

A thermal hydrodynamic (THD) model and dynamic model of single mass rigid rotor system were established by taking conical hybrid bearing with shallow and deep pockets as the research object, dynamic coefficient and stability parameters of bearing-rotor system were obtained by using finite element method (FEM) and finite difference method (FDM) to solve computational models of Reynolds equation, energy equation and viscosity-temperature equation. Minimum oil film thickness was obtained based on bearing force balance. Dynamic coefficient was compared with previous findings.

Findings

After considering thermal effect, the dimensionless critical mass decreases, a significant decrease in the instability speed, and the stability of the system decreases greatly; the minimum oil film thickness decreases because of thermal effect.

Originality/value

The thermal effect is combined with dynamic characteristics to analyze stability of the rotor system for a conical hybrid bearing. Influence of thermal effect on minimum oil film thickness is studied.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2019-0542/

Details

Industrial Lubrication and Tribology, vol. 72 no. 10
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 3 April 2019

Hong Guo, Shuai Yang, Shaolin Zhang and Zebin Zhang

The purpose of this paper is to study the influence of lubricant temperature-viscosity on the performance for a hydrodynamic journal floating ring bearing (FRB), including…

153

Abstract

Purpose

The purpose of this paper is to study the influence of lubricant temperature-viscosity on the performance for a hydrodynamic journal floating ring bearing (FRB), including ring-journal speed ratio and stability.

Design/methodology/approach

The finite difference method was used to solve computational models of Reynolds equation, energy equation and temperature–viscosity equation. Dynamic coefficients were obtained based on the floating ring balance. The dynamic model of journal and floating ring was established to deduce the stability criterion of single mass symmetrical rigid FRB rotor system by the Routh–Hurwitz method. The outlet temperature and ring-journal speed ratio under different journal speeds were compared to experimental data.

Findings

The temperature–viscosity effect reduces the ring-journal speed ratio and stability of rotor system. According to theoretical and experimental results, the outlet temperature rises and ring-journal ratio drops when the journal speed rises.

Originality/value

The temperature–viscosity effect is combined with dynamic characteristics to analyze the stability of the rotor system and lubrication mechanism for an FRB. Influence of temperature–viscosity on the ring-journal ratio and multi-stable regions of system are studied.

Details

Industrial Lubrication and Tribology, vol. 71 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 9 June 2021

Prashant G. Khakse and Vikas M. Phalle

This paper aims to describe how successfully a particular restrictor delivers its best in increasing the conical journal bearing performance. The restrictors are used in the…

90

Abstract

Purpose

This paper aims to describe how successfully a particular restrictor delivers its best in increasing the conical journal bearing performance. The restrictors are used in the hole-entry conical journal bearing subjected to hybrid mode. Thus, the restrictors, like constant flow valve (CFV), orifice and capillary, are studied comparatively.

Design/methodology/approach

Numerical simulation for the bearing results with the three restrictors are obtained by using finite element method (FEM) under the well-known modified Reynolds equation.

Findings

When the hole-entry conical journal bearings, with the restrictor design parameter range C¯s2 = 0.03 – 0.09, are operated, the results obtained are quite distinctive and significant. It indicates that the CFV restrictor-based conical bearing gives enhanced performance in comparison to orifice and capillary restrictors. Moreover, it suggests the performance-wise sequence of the restrictors in hybrid bearings as CFV > Orifice > Capillary.

Originality/value

The outcome of the research paper will give insight to help the bearing designer to choose the particular restrictor in hybrid conical bearing depending on the industrial need.

Details

Industrial Lubrication and Tribology, vol. 73 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 2 January 2023

Dinesh Haribhau Kamble, Vikas M. Phalle, Shankar S. Mantha and Sanjay Rangrao Pawar

Where combined radial and axial loads act on the bearing, the conical journal bearing is best suited. Large turbines, generators, compressors and other machinery perform better…

136

Abstract

Purpose

Where combined radial and axial loads act on the bearing, the conical journal bearing is best suited. Large turbines, generators, compressors and other machinery perform better while using conical hydrodynamic journal bearings (CHJBs). The bearings worn out and the performance suffered because of regular use and numerous start and stop operations.

Design/methodology/approach

The performance of CHJB is evaluated using both analytical and experimental methods in this paper. The analytical method for resolving Reynolds equation uses spherical coordinate system and finite element analysis. On the CHJB test rig, data is collected for different radial loads with 10°, 20° and 30° semi-cone angles using hydraulic oil of viscosity grade ISO VG46.

Findings

The findings of this paper demonstrate that at various semi-cone angles for worn-out bearings, the maximum pressure developed increases with increasing radial load.

Originality/value

This paper provides analytical and experimental performance of CHJBs considering the effect of abrasive wear that is caused because of frequent start and stop operations of machine. The results of wear impact on CHJBs will be helpful for researchers and design engineers.

Details

Industrial Lubrication and Tribology, vol. 75 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 May 2000

Xinmin Dai, Amy H. Lau and Ji‐liang Yang

Explains why, following China‘s implementation of a market economy, public accounting firms were required to affiliate (hook‐up) with existing government or educational…

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Abstract

Explains why, following China‘s implementation of a market economy, public accounting firms were required to affiliate (hook‐up) with existing government or educational institutions until 1993 when partnerships and limited liability firms were also allowed. Describes the rules relating to independent accounting firms and changes which should foster their development but reports that, in fact, most firms are still affiliated. Discusses the reasons for this and the resulting problems, e.g. lack of competition and independence, low quality of service and increases in fraud, misrepresentation and under‐disclosure. Reveals that despite the 1995 exposure draft on eliminating the hooking‐up structure few de‐affiliations have taken place and identifies four problems which need solving if full de‐affiliation is to be achieved.

Details

Managerial Finance, vol. 26 no. 5
Type: Research Article
ISSN: 0307-4358

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Article
Publication date: 22 September 2023

Xinmin Peng, Lumin He, Shuai Ma and Martin Lockett

An alliance portfolio can help latecomer firms to acquire the necessary knowledge and resources to catch up with market leaders. However, how latecomer firms construct an alliance…

96

Abstract

Purpose

An alliance portfolio can help latecomer firms to acquire the necessary knowledge and resources to catch up with market leaders. However, how latecomer firms construct an alliance portfolio in terms of the nature of windows of opportunity has not been fully analyzed. This paper aims to explore how latecomer firms can build appropriate coalitions according to the nature of the window of opportunity to achieve technological catch-up in different catch-up phases.

Design/methodology/approach

Based on a longitudinal case study from 1984 to 2018 of Sunny Group, now a leading manufacturer of integrated optical components and products, this paper explores the process of technological catch-up of latecomer firms building different types of alliance portfolio in different windows of opportunity.

Findings

This paper finds that there is a sequence when latecomers build an alliance portfolio in the process of catch-up. When the uncertainty of opportunity increases, the governance mechanism of the alliance portfolio will change from contractual to equity-based. Also, latecomer firms build market-dominated and technology-dominated alliance portfolios to overcome their market and technology disadvantages, respectively.

Originality/value

These conclusions not only enrich the theory of latecomer catch-up from the perspective of windows of opportunity but also expand research on alliance portfolio processes from a temporal perspective.

Details

Nankai Business Review International, vol. 15 no. 3
Type: Research Article
ISSN: 2040-8749

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Book part
Publication date: 2 September 2009

C. Cindy Fan

The assumption that the family migrates as a unit downplays migrants’ circularity. This chapter focuses on China's rural–urban labor migrants that travel back and forth between…

Abstract

The assumption that the family migrates as a unit downplays migrants’ circularity. This chapter focuses on China's rural–urban labor migrants that travel back and forth between the sites of work and home community and between places of work. I argue that migrants and their households pursue work flexibility in order to obtain the best of the urban and rural worlds, by gaining earnings from urban work and at the same time maintaining social and economic security in the countryside. Work flexibility demands flexibility in household organization, in the form of division of labor and collaboration between genders, generations, and households. Based on a study in Sichuan, I examine household biographies and narratives to identify migrants’ work and household strategies.

Migrants change jobs frequently, switch from one type of work to another and one location to another readily, and often return to the home village for months or even years before pursuing migrant work again. Not only are migrants ready to split the household between the city and the countryside, but also they frequently change from one form of division of labor to another. The inside–outside model, where the wife stays in the village and the husband does migrant work, used to be the dominant arrangement. Over time, the outside–outside model, where both the husband and wife migrate to work and leave behind other family members, is increasingly popular. This is facilitated by intergenerational and interhousehold division of labor in the form of assistance by the extended family. Intergenerational division of labor takes place when the second generation is replacing the parents in migrant work. This research's findings support the notion that rural–urban migrants are fast becoming a hybrid segment of Chinese society, playing dual roles of farmers and urban workers and straddling the peasant and urban worlds.

Details

Work and Organizationsin China Afterthirty Years of Transition
Type: Book
ISBN: 978-1-84855-730-7

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Article
Publication date: 17 October 2022

Xinmin Tian, Zhiqiang Zhang, Cheng Zhang and Mingyu Gao

Considering the role of analysts in disseminating information, the paper explains the idiosyncratic volatility puzzle of China's stock market. As the largest developing country…

333

Abstract

Purpose

Considering the role of analysts in disseminating information, the paper explains the idiosyncratic volatility puzzle of China's stock market. As the largest developing country, China's research can provide meaningful reference for the research of financial markets in other new countries.

Design/methodology/approach

From the perspective of behavior, establishing a direct link between individual investor attention and stock price overvaluation.

Findings

The authors find that there is a significant idiosyncratic volatility puzzle in China's stock market. Due to the role of mispricing, individual investor attention significantly enhances the idiosyncratic volatility effect, that is, as individual investor attention increases, the greater the idiosyncratic volatility, the lower the expected return. Attention can explain the idiosyncratic volatility puzzle in China's stock market. In addition, due to the role of information production and dissemination, securities analysts can reduce the degree of market information asymmetry and enhance the transparency of market information.

Originality/value

China is the second largest economy in the world, and few scholars analyze it from the perspective of investors' attention. The authors believe this paper has the potential in contributing to the academia.

Details

International Journal of Emerging Markets, vol. 19 no. 7
Type: Research Article
ISSN: 1746-8809

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Article
Publication date: 12 March 2021

Xinmin Peng, Keyi Fang and Martin Lockett

Emerging-market multinational enterprises (EMNEs) can choose focused or ambidextrous strategies to catch up with global market leaders through overseas foreign direct investment…

591

Abstract

Purpose

Emerging-market multinational enterprises (EMNEs) can choose focused or ambidextrous strategies to catch up with global market leaders through overseas foreign direct investment (OFDI). The Belt and Road Initiative (BRI), launched by the Chinese government in 2013, had a profound impact on Chinese multinational enterprises’ international behavior. This paper analyses how EMNEs select focused or ambidextrous catch-up strategies before and after the BRI, integrating ambidexterity and catch-up theories to provide a more nuanced understanding of the evolution of EMNE strategy.

Design/methodology/approach

A case study is well suited for deriving rich descriptions of empirical phenomena for which little theory exists. Because the existing literature has not yet fully explored and conceptually modeled the influence of windows of opportunity on international catch-up strategies, we use qualitative research to explore the mechanisms of strategy evolution in EMNEs.

Findings

The results show that the choice of catch-up strategy is influenced by the nature of windows of opportunity and the firm's accumulated technological capability. Specifically, the opening of institutional windows as a result of the BRI could give significant momentum to the international catch-up process by providing incentives and opportunities for EMNEs to enter more markets and new technology fields. The EMNEs studied underwent a transition from a focused strategy in the catch-up stage to an ambidextrous strategy in the beyond catch-up stage.

Originality/value

These conclusions can not only deepen our understanding of the dynamics of catch-up strategies in the global context but also enrich the research on the ambidexterity of EMNEs, especially in the context of the BRI.

Details

Cross Cultural & Strategic Management, vol. 28 no. 2
Type: Research Article
ISSN: 2059-5794

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