Cheng-Jun Wang and Jonathan J.H. Zhu
Social influence plays a crucial role in determining the size of information diffusion. Drawing on threshold models, we reformulate the nonlinear threshold hypothesis of social…
Abstract
Purpose
Social influence plays a crucial role in determining the size of information diffusion. Drawing on threshold models, we reformulate the nonlinear threshold hypothesis of social influence.
Design/methodology/approach
We test the threshold hypothesis of social influence with a large dataset of information diffusion on social media.
Findings
There exists a bell-shaped relationship between social influence and diffusion size. However, the large network threshold, limited diffusion depth and intense bursts become the bottlenecks that constrain the diffusion size.
Practical implications
The practice of viral marketing needs innovative strategies to increase information novelty and reduce the excessive network threshold.
Originality/value
In all, this research extends threshold models of social influence and underlines the nonlinear nature of social influence in information diffusion.
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The purpose of this paper is to study the triple helix (TH) of Chinese university‐industry‐government relationships.
Abstract
Purpose
The purpose of this paper is to study the triple helix (TH) of Chinese university‐industry‐government relationships.
Design/methodology/approach
Following an evolution path of TH in China, the relations among the actors for innovation have been analyzed and then it is realized that it is not university‐government‐academe relations, but “university‐industry‐government relations”.
Findings
The paper points out some limitations and flaws of university‐industry‐academy and brings forward the evolutionary path to TH of university‐industry‐government collaboration and development to cope with these practical and theoretical problems.
Originality/value
The author asserts that university‐industry‐government should be affirmed, not university‐industry‐academy in China for truth, which can dialogue with international academic circles.
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Zhaoqiang Wang, Jun Cheng, Hong Ji, Shan Hu and Hao Chen
The purpose of this paper is to study the effects of single parameters for temperature characteristics of oil film in port plate pair and the relationship of calculated results…
Abstract
Purpose
The purpose of this paper is to study the effects of single parameters for temperature characteristics of oil film in port plate pair and the relationship of calculated results and experimental results under different viscosity.
Design/methodology/approach
The paper established the mathematical model of oil film of port plate pair, calculated the energy equation of port plate pair, simulated for the oil film and temperature distribution and selected different kinds of lubricants to analyze the calculated value and the experimental value.
Findings
The results show: temperature rise of port plate pair is reduced with the increase of oil viscosity; temperature rise of port plate pair is decreased with rise of initial oil film thickness; temperature rise of port plate pair is increased with the rise of cylinder body speed, inclination angle and sealing belt width; and through the comparison of calculated value and experimental value, under the same viscosity and cylinder speed, experimental results are bigger.
Originality/value
This paper used the methods that the temperature of port plate pair was calculated numerically, and the results were consistent with experimental results, so it can get high precision.
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Xinli Li, Jun Cheng, Shouyi Wan and Zhenyang Zhao
This study aims to investigate the impact of institutional fragility on the innovation investments of enterprises by analyzing the moderating effect of government subsidies and…
Abstract
Purpose
This study aims to investigate the impact of institutional fragility on the innovation investments of enterprises by analyzing the moderating effect of government subsidies and the integration of industry and finance.
Design/methodology/approach
Multiple regression analysis was used on 10,838 samples of 2,356 listed companies in China for the period 2007–2017, to empirically test the influence of institutional fragility on innovation investment. Moreover, Heckman’s two-stage approach was used for the robustness of the regression results.
Findings
The results show that the relationship between institutional fragility and innovation investment is an inverted U-shaped; government subsidies negatively moderate the relationship between institutional fragility and innovation investment, while the integration of industry and finance positively moderates them. Further analysis shows that the relationship between institutional fragility and innovation investment is more significant for high-tech enterprises. Similarly, the relationship between institutional fragility and innovation output also presents an inverted U-shape, which mainly affects enterprises’ breakthrough innovation output, but has no substantial impact on the incremental innovation output.
Originality/value
The conclusions provide new ideas for guiding the government’s reform, promoting the integration of industry and finance and promoting enterprise innovation.
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Jun Cheng and Chunxing Gu
As the crucial support component of the propeller power system, the reliability of the operation of submersible pumps is influenced by the lubrication performance of…
Abstract
Purpose
As the crucial support component of the propeller power system, the reliability of the operation of submersible pumps is influenced by the lubrication performance of water-lubricated thrust bearings. When the water-lubricated thrust bearings are under start-stop or heavy load conditions, the effect of surface morphology is crucial as the mixed lubrication regime is encountered. This paper aims to develop one mixed lubrication model for the water-lubricated thrust bearings to predict the effects of surface skewness, kurtosis and roughness orientation on the loading carrying capacity and tribological behavior.
Design/methodology/approach
This paper developed one improved mixed lubrication model specifically for the water-lubricated thrust bearing system. In this model, the hydrodynamic model was improved by using the height of the rough surface and its probability density function, combined with the average flow model. The asperity contact model was improved by using the equation for the Pearson system of frequency curves to characterize the non-Gaussian aspect of surface roughness distribution.
Findings
According to the results, negative skewness, large kurtosis and lateral surface pattern can improve the tribological performance of water-lubricated thrust bearings. Optimizing the surface morphology is a reasonable design method that can improve the performance of water-lubricated thrust bearings.
Originality/value
In this paper, one mixed lubrication model specifically for the water-lubricated thrust bearing with the effect of surface roughness into consideration was developed. Based on the developed model, the effect of surface morphology on tribological behavior can be evaluated.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2023-0247/
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Germanico Gonzalez-Badillo, Hugo I. Medellin-Castillo, Theodore Lim, James M. Ritchie, Raymond C.W. Sung and Samir Garbaya
In this study, a new methodology to evaluate the performance of physics simulation engines (PSEs) when used in haptic virtual assembly applications is proposed. This methodology…
Abstract
Purpose
In this study, a new methodology to evaluate the performance of physics simulation engines (PSEs) when used in haptic virtual assembly applications is proposed. This methodology can be used to assess the performance of any physics engine. To prove the feasibility of the proposed methodology, two-third party PSEs – Bullet and PhysXtm – were evaluated. The paper aims to discuss these issues.
Design/methodology/approach
Eight assembly tests comprising variable geometric and dynamic complexity were conducted. The strengths and weaknesses of each simulation engine for haptic virtual assembly were identified by measuring different parameters such as task completion time, influence of weight perception and force feedback.
Findings
The proposed tests have led to the development of a standard methodology by which physics engines can be compared and evaluated. The results have shown that when the assembly comprises complex shapes, Bullet has better performance than PhysX. It was also observed that the assembly time is directly affected by the weight of virtual objects.
Research limitations/implications
A more comprehensive study must be carried out in order to evaluate and compare the performance of more PSEs. The influence of collision shape representation algorithms on the performance of haptic assembly must be considered in future analysis.
Originality/value
The performance of PSEs in haptic-enabled VR applications had been remained as an unknown issue. The main parameters of physics engines that affect the haptic virtual assembly process have been identified. All the tests performed in this study were carried out with the haptic rendering loop active and the objects manipulated through the haptic device.
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PingJun Xia, António M. Lopes and Maria Teresa Restivo
Virtual reality (VR) for product assembly has been studied for more than 20 years but its practical application in industry is still very much in its infancy. Haptics is a new and…
Abstract
Purpose
Virtual reality (VR) for product assembly has been studied for more than 20 years but its practical application in industry is still very much in its infancy. Haptics is a new and important interaction method for VR and a strong and growing research area, however, it still remains a virtually unknown concept for industrial application.
Design/methodology/approach
This paper provides a comprehensive survey of VR and haptics for product assembly, from rigid parts to soft cables.
Findings
Some new ideas and research progresses in recent years are especially investigated. First the concepts and classifications of virtual assembly are introduced and the different virtual environment systems for product assembly are discussed. Then the major research groups, typical systems and major research issues are explored in detail, treating rigid parts and soft cables separately. Lastly, the barriers preventing successful application of virtual assembly are discussed and future research directions are also summarized.
Originality/value
The paper provides an overview and analysis of VR and haptics for product assembly, including both rigid parts and soft cables.
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Keyan Liu, Xuyue Yin, Xiumin Fan and Qichang He
The purpose of this paper is to give a comprehensive survey on the physics-based virtual assembly (PBVA) technology in a novel perspective, to analyze current drawbacks and…
Abstract
Purpose
The purpose of this paper is to give a comprehensive survey on the physics-based virtual assembly (PBVA) technology in a novel perspective, to analyze current drawbacks and propose several promising future directions.
Design/methodology/approach
To provide a deep insight of PBVA, a discussion of the developing context of PBVA and a comparison against constraint-based virtual assembly (CBVA) is put forward. The core elements and general structure are analyzed based on typical PBVA systems. Some common key issues as well as common drawbacks are discussed, based on which the research trend and several promising future directions are proposed.
Findings
Special attention is paid to new research progresses and new ideas concerning recent development as well as new typical systems of the technology. Advantages of PBVA over CBVA are investigated. Based on the analysis of typical PBVA systems and the evolution of PBVA, the core elements of the technology and the general structure of its implementation are identified. Then, current PBVA systems are summarized and classified. After that, key issues in the technology and current drawbacks are explored in detail. Finally, promising future directions are given, including both the further perfecting of the technology and the combination with other technologies.
Originality/value
The PBVA technology is put into a detailed review and analysis in a novel way, providing a better insight of both the theory and the implementation of the technology.
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Germanico Gonzalez-Badillo, Hugo Medellin-Castillo, Theodore Lim, James Ritchie and Samir Garbaya
This paper aims to report the development and key features of a novel virtual reality system for assembly planning and evaluation called Haptic Assembly and Manufacturing System…
Abstract
Purpose
This paper aims to report the development and key features of a novel virtual reality system for assembly planning and evaluation called Haptic Assembly and Manufacturing System (HAMS). The system is intended to be used as a tool for training, design analysis and path planning.
Design/methodology/approach
The proposed system uses the physics-based modelling (PBM) to perform assemblies in virtual environments. Moreover, dynamic assembly constrains have been considered to reduce the degrees of freedom of virtual objects and enhance the virtual assembly performance.
Findings
To evaluate the effectiveness and performance of HAMS, the assembly of various mechanical components has been carried out, and the results have shown that it can be effectively used to simulate, evaluate, plan and automatically formalise the assembly of complex models in a more natural and intuitive way.
Research limitations/implications
The collision detection performance is the bottleneck in any virtual assembly system. New methods of collision shape representation and collision detection algorithms must be considered.
Originality/value
HAMS introduces the use of dynamic assembly constraints to enhance the virtual assembly performance. HAMS also uses features not yet reported by similar systems in the literature. These features include: automatic or manual definition of assembly constraints within the virtual assembly system; the implementation of control panels and widgets to modify simulation parameters during running time to evaluate its influence on simulation performance; assembly data logging such as trajectories, forces and update rates for post-processing, further analysis or its presentation in the form of chronocyclegraphs to graphically analyse the assembly process.