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Article
Publication date: 22 February 2013

Jianfeng Zhang and Wenxiu Hu

The purpose of this paper is to examine whether realized volatility can provide additional information on the volatility process to the GARCH and EGARCH model, based on the data…

561

Abstract

Purpose

The purpose of this paper is to examine whether realized volatility can provide additional information on the volatility process to the GARCH and EGARCH model, based on the data of Chinese stock market.

Design/methodology/approach

The realized volatility is defined as the squared overnight return plus the close to open squared return of the period between the morning and afternoon session, to plus the sum of the squared f-minute returns between the trading hours during the relevant trading day. The methodology is a GARCH (EGARCH) model with added explanation variables in the variance equation. The estimation methodology is exact maximum likelihood estimation, using the BHHH algorithms for optimization.

Findings

There are some stocks for which realized volatility measures add information in the volatility process, but there are still quite a number of stocks for which they do not contain any additional information. The 30 minutes realized volatility measures outperform measures constructed on other time intervals. The firm size, turnover rate, and amplitude also partially explain the difference in realized volatility ' s explanatory power across firms.

Research limitations/implications

When analyzing the factors determining the role of realized volatility, as the difficulty of getting the data, ownership structure and ultimately ownerships are not taken into account, except for the turnover ratio, amplitude and size.

Originality/value

This study extends firstly this line of inquiry of realized volatility into the emerging Chinese stock market. Due to the unique institutional setting in China, the results of this study have played an important role on pricing warrant for domestic investors in the Chinese market.

Details

International Journal of Managerial Finance, vol. 9 no. 1
Type: Research Article
ISSN: 1743-9132

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Article
Publication date: 12 May 2022

Cheng Zhang, Jianfeng Zhou and Xiannian Meng

In the magnetorheological fluid (MRF) sealing, a large amount of friction heat is generated in the fluid film with micron thickness due to the viscosity dissipation, which leads…

325

Abstract

Purpose

In the magnetorheological fluid (MRF) sealing, a large amount of friction heat is generated in the fluid film with micron thickness due to the viscosity dissipation, which leads to seal failure and MRF deterioration. The purpose of this study is to investigate the mechanism of temperature rise of MRF film under the action of the three-field coupling of the flow field, temperature field and magnetic field.

Design/methodology/approach

The fluid film was simplified as a Couette flow in this work to simulate the temperature change in the sealing fluid film under different working conditions. The corresponding experiment for test the temperature rise was also carried out, and the temperature of the characteristic point of the stationary ring was measured to validate the model.

Findings

The results show that the temperature rise is mainly affected by the rotational speed, magnetic field strength and fluid film thickness. The magnetic field enhances the convective heat transfer in the MRF film. The thinner the fluid film, the more frictional heat generated. The MRF film reaches its maximum temperature at the contact with the end face of rotating ring due to frictional heat.

Originality/value

A method for temperature rise analysis of MRF fluid sealing films based on Couette flow is established. It is helpful for the study of liquid film frictional heat in MRF seals.

Details

Industrial Lubrication and Tribology, vol. 74 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 8 January 2020

Jianfeng Jia, Shunyi Zhou, Long Zhang and Xiaoxiao Jiang

Drawn upon the perspective of implicit voice theory, the purpose of this paper is to explore the underlying mechanism as well as the boundary effect in the relationship between…

1848

Abstract

Purpose

Drawn upon the perspective of implicit voice theory, the purpose of this paper is to explore the underlying mechanism as well as the boundary effect in the relationship between paternalistic leadership and voice behavior.

Design/methodology/approach

Multiple-wave survey data from a sample of 368 employees in China were used to test the hypothesized moderated mediation model.

Findings

The findings show that both benevolent leadership and moral leadership related positively to voice behavior, whereas authoritative leadership played a negative role in influencing voice behavior. Employees’ implicit voice belief played a partial mediating role between paternalistic leadership and voice behavior. Furthermore, perceived HRM strength weakens both the mediation relationship among benevolent leadership, implicit voice belief and voice behavior, and the mediation relationship among moral leadership, implicit voice belief and voice behavior. However, the moderated mediation effect of implicit voice belief on the relationship between authoritative leadership and voice behavior is not significant.

Practical implications

Leaders are encouraged to behave benevolently and morally whereas to avoid excessive authoritative style at work, so that employees can be encouraged to speak out. Organizations are advised to introduce management practices like training and development sessions and to improve employees’ perceived HRM strength so that the implicit voice belief can be reduced, and the voice behavior can be stimulated.

Originality/value

The research provided a fresh theoretical perspective on the underlying mechanism between paternalistic leadership and employees’ voice behavior by unveiling employee implicit voice belief’s partial mediating role between paternalistic leadership and employee voice behavior. Furthermore, the study contributed to the literature of voice by adopting a more integrative perspective and exploring the role of the implementation of the organization’s system, i.e., perceived HRM strength that provided a boundary condition in the above mediation model.

Details

Employee Relations: The International Journal, vol. 42 no. 2
Type: Research Article
ISSN: 0142-5455

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Article
Publication date: 8 February 2021

Yonggui Wang, Zeng Zhang, Jianfeng Wang, Rui Sang and Weigang Zhang

A kind of the Z-6020/E-44 modified waterborne hydroxyl acrylate resin (Z-WEA) and its application in volatile organic compound-free waterborne coatings were prepared.

356

Abstract

Purpose

A kind of the Z-6020/E-44 modified waterborne hydroxyl acrylate resin (Z-WEA) and its application in volatile organic compound-free waterborne coatings were prepared.

Design/methodology/approach

The Z-6020/E-44 modified waterborne hydroxyl acrylate resin (Z-WEA) was obtained dropwise by adding a mixed solution of methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, acrylic acid and an initiator into a pre-prepared solution of isopropyl alcohol and E-44 and by semi-continuous solution polymerization, and this chain was further extended with organosiloxane (Z-6020) through graft copolymer, which was then neutralized with organic base and dispersed with water, with waterborne amino resin curing agent to form a film, and the properties were tested.

Findings

The results showed that when the dosage of initiator was 2.5% accounts for the total acrylic monomer, the hydroxyl content was 10%; the dosage of E-44 was 16%; the dosage of Z-6020 was 6%; the mass ratio of hard and soft monomer was 2.0:1; the neutralization was 100%; Z-6020/E-44 modified waterborne hydroxyl acrylate resin (Z-WEA) had excellent dispersion performance in water and storage stability; water absorption of cured film was 7.8%; pencil hardness reached 5H; adhesive force was 1 level; and the film was uniform and endowed with remarkable heat resistance, high gloss and good fullness.

Practical implications

This paper established a method to synthesize Z-6020/E-44 modified waterborne hydroxyl acrylate resin (Z-WEA) with green surfactants that can be used in the coatings, adhesives, finishing agents and so on.

Originality/value

This paper provides a method of preparing Z-6020/E-44 modified waterborne hydroxyl acrylate resin (Z-WEA) and with waterborne amino resin curing agent to form a film, and the film is uniform and endowed with remarkable heat resistance, high gloss and good fullness and meets the requirements of high-grade paint.

Details

Pigment & Resin Technology, vol. 50 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 25 June 2019

Chunlei Shao, Aixia He, Zhongyuan Zhang and Jianfeng Zhou

The purpose of this paper is to study the transition process from the crystalline particles appearing before the pump inlet to the stable operation of the pump.

131

Abstract

Purpose

The purpose of this paper is to study the transition process from the crystalline particles appearing before the pump inlet to the stable operation of the pump.

Design/methodology/approach

Firstly, a modeling test method was put forward for the high-temperature molten salt pump. Then, according to a modeling test scheme, the experiment of the solid–liquid two-phase flow was carried out by using a model pump similar to the prototype pump. Meanwhile, the numerical method to simulate the transition process of a molten salt pump was studied, and the correctness of the numerical model was verified by the experimental results. Finally, the transition process of the molten salt pump was studied by the verified numerical model in detail.

Findings

In the simulation of the transition process, it is more accurate to judge the end of the transition process based on the unchanged particle volume fraction (PVF) at the pump outlet than on the periodic fluctuation of the outlet pressure. The outlet pressure is closely related to the PVF in the pump. The variation of the outlet pressure is slightly prior to that of the PVF at the pump outlet and mainly affected by the PVF in the impeller and volute. After 0.63 s, the PVF at each monitoring point changes periodically, and the time-averaged value does not change with time.

Practical implications

This study is of great significance to further improve the design method of molten salt pump and predict the abrasion characteristic of the pump due to interactions with solid particles.

Originality/value

A numerical method is established to simulate the transition process of a molten salt pump, and a method is proposed to verify the numerical model of two-phase flow by modeling test.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 9
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 8 November 2018

Lekai Zhang, Jianfeng Wu, Kejun Zhang, Kevin Wolterink and Baixi Xing

The acceleration of globalization is causing global trade transactions to become increasingly frequent, which leads to the internationalized design of consumer products. However…

906

Abstract

Purpose

The acceleration of globalization is causing global trade transactions to become increasingly frequent, which leads to the internationalized design of consumer products. However, due to cultural differences, the user experience in different parts of the world with the same product may be different. In addition, the user experience is not static, but changes over the different usage stages for a product since the role of our senses may vary and different emotions may be elicited. Therefore, the purpose of this paper is to explore how the interaction between the user and the product influences cross-cultural sensory modalities and emotional responses to products.

Design/methodology/approach

Due to the fact that drinking tea can provide dynamic feedback of users’ sensory experiences including all five senses, two kinds of tea products from two considerably different cultures (China and the Netherlands) were chosen for the study. The experiment was conducted in five stages corresponding to different levels of interaction with two tea products. Measurements for both Chinese and Dutch participants were conducted by means of collecting subjective data for sensory modalities and emotions related to product experiences throughout the five stages.

Findings

Results showed that tea experience tends to be dynamic between the two different countries over different usage periods, including sensory modalities and the emotional responses.

Practical implications

The findings and design & market implications can be applied to optimize the design or market of international tea products or consumer products in other categories. They will be helpful for the international marketing of tea, especially for those who are interested in breaking into the Chinese tea market and those who are interested in promoting Chinese tea in new markets. In addition, the authors’ methods to evaluate the dynamics of the importance of sensory modalities and emotions could be used to test the user experience in the product lifecycle to help develop a successful international product.

Originality/value

The findings and the linked design implications could be important not only for a theoretical understanding of cross-cultural sensory and emotional feedback from a product experience, but also for the optimization of product design for the international market.

Details

Asia Pacific Journal of Marketing and Logistics, vol. 30 no. 5
Type: Research Article
ISSN: 1355-5855

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Article
Publication date: 30 July 2020

Xu Li, Jun Li, Xiaoyi Zhang, Jianfeng Gao and Chao Zhang

Viscous dampers are commonly used in large span cable-stayed bridges to mitigate seismic effects and have achieved great success.

242

Abstract

Purpose

Viscous dampers are commonly used in large span cable-stayed bridges to mitigate seismic effects and have achieved great success.

Design/methodology/approach

However, the nonlinear analysis on damper parameters is usually computational intensive and nonobjective. To address these issues, this paper proposes a simplified method to determine the viscous damper parameters for double-tower cable-stayed bridges. An empirical formula of the equivalent damping ratio of viscous dampers is established through decoupling nonclassical damping structures and linearization of nonlinear viscous dampers. Shaking table tests are conducted to verify the feasibility of the proposed method. Moreover, this simplified method has been proved in long-span cable-stayed bridges.

Findings

The feasibility of this method is verified by the simplified model shaking table test. This simplified method for determining the parameters of viscous dampers is verified in cable-stayed bridges with different spans.

Originality/value

This simplified method has been validated in cable-stayed bridges with various spans.

Details

Engineering, Construction and Architectural Management, vol. 27 no. 8
Type: Research Article
ISSN: 0969-9988

Keywords

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Article
Publication date: 26 September 2019

Leiyu Zhang, Jianfeng Li, Shuting Ji, Peng Su, Chunjing Tao and Run Ji

Upper-limb joint kinematics are highly complex and the kinematics of rehabilitation exoskeletons fail to reproduce them, resulting in hyperstaticity and human–machine…

240

Abstract

Purpose

Upper-limb joint kinematics are highly complex and the kinematics of rehabilitation exoskeletons fail to reproduce them, resulting in hyperstaticity and human–machine incompatibility. The purpose of this paper is to design and develop a compatible exoskeleton robot (Co-Exos II) to address these problems.

Design/methodology/approach

The configuration synthesis of Co-Exos II is completed using advanced mechanism theory. A compatible configuration is selected and four passive joints are introduced into the connecting interfaces based on optimal configuration principles. A Co-Exos II prototype with nine degrees of freedom (DOFs) is developed and still owns a compact structure and volume. A new approach is presented to compensate the vertical glenohumeral (GH) movements. Co-Exos II and the upper arm are simplified as a guide-bar mechanism at the elevating plane. The theoretical displacements of passive joints are calculated by the kinematic model of the shoulder loop. The compatible experiments are completed to measure the kinematics of passive joints.

Findings

The compatible configuration of the passive joints can effectively reduce the gravity influences of the exoskeleton device and the upper extremities. The passive joints exhibit excellent compensation effect for the GH joint movements by comparing the theoretical and measured results. Passive joints can compensate for most GH movements, especially vertical movements.

Originality/value

Co-Exos II possesses good human–machine compatibility and wearable comfort for the affected upper limbs. The proposed compensation method is convenient to therapists and stroke patients during the rehabilitation trainings.

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Article
Publication date: 8 January 2018

Jianmei Wang, Zhixiong Li, Sadoughi Mohammadkazem, Min Cai, Jianfeng Kang and Yanan Zhang

The stability characteristics of an oil film directly influence the safety and service life of mill oil-film bearings. However, very limited work has been done to address the…

199

Abstract

Purpose

The stability characteristics of an oil film directly influence the safety and service life of mill oil-film bearings. However, very limited work has been done to address the stability characteristics of mill oil-film bearings. To this end, this paper aims to investigate the stability characteristics of mill oil-film bearings through theoretical and experimental analysis.

Design/methodology/approach

For the first time, a special designed experiment platform was developed to investigate the stability characteristics of mill oil-film bearings. In addition, a theoretical model of lubricating film of the tested bearings was established to analyze the oil-film stability. The theoretical results were compared with the experimental results.

Findings

The comparison results demonstrate that the critical influential factors on the bearing stability were the eccentricity ratio and the ratio of bearing length to diameter. The mill bearing was likely to be unstable under a small load and at a high rotational speed.

Practical implications

The paper includes implications for suitable operation conditions in practical use of mill oil-film bearings.

Originality/value

This paper fulfills an identified need to investigate oil-film stability of mill bearings for practical applications.

Details

Industrial Lubrication and Tribology, vol. 70 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 29 May 2019

Penggao Zhang, Boqin Gu, Jianfeng Zhou and Long Wei

The purpose of this study is to investigate the heat transfer characteristics in a spiral groove mechanical seal lubricated by magnetic fluid.

152

Abstract

Purpose

The purpose of this study is to investigate the heat transfer characteristics in a spiral groove mechanical seal lubricated by magnetic fluid.

Design/methodology/approach

The viscosity relationship of magnetic fluid in external electromagnetic field was deduced. The temperature distribution of sealing ring was calculated by the method of separation variables.

Findings

It has been found that the rotating ring absorbs most friction heat. The temperatures on the end faces of rotating ring and stationary ring decrease from inner radius to outer radius, the temperature of magnetic fluid film decreases from rotating ring to stationary ring and the highest temperature of the sealing system is at the junction of the inner radius and the end face of rotating ring.

Originality/value

Selecting the sealing rings with higher thermal conductivity and reducing the volume fraction of solid particles in magnetic fluid can reduce the temperature of sealing system effectively.

Details

Industrial Lubrication and Tribology, vol. 71 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

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