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Article
Publication date: 29 August 2019

Wei Long, Mimi Wu, Fasha Li, Jiyao Wang and Wei Deng

The purpose of this paper is to develop the micro-electro-mechanical systems (MEMS) technology has created the conditions for the study of microfluidic technology…

Abstract

Purpose

The purpose of this paper is to develop the micro-electro-mechanical systems (MEMS) technology has created the conditions for the study of microfluidic technology. Microfluidic technology has become a very large branch in the MEMS field over the past decade. For aerostatic thrust bearing, the micro-fluidic gas flow in a small-scale gas film between two parallel plates is the subject of many studies. Because of the thin gas in the film, velocity slip occurs at the interface, which causes the gas flow pattern to change in the lubricating film. So, it is important to clarify the mechanism and pressure characteristics in thin firm gas flow.

Design/methodology/approach

First, a new assumption and corresponding models for the flow regime were established by theoretical analysis. Second, computational simulations about pressure distribution and velocity were given by a large-scale atomic/molecular massively parallel simulator (LAMMPS). Third, comparison of the results of LAMMPS simulation and direct simulation Monte Carlo calculation were made to verify the reliability of above results.

Findings

The gas flow mechanism and corresponding regulations are significantly different from traditional pneumo dynamics, which can be described by Navier–Stokes equations accurately. Combining theatrical study and computational results, the stratification theory of the gas film was verified. The research shows that when the gas flow rate increased, the pressure of the gas film decreased, the thickness of the continuous flow layer increased, the thickness of the thin layer decreased and the layered pressure in the gas film disappeared. In this case, velocity slippage could be ignored.

Originality/value

First, this paper established an analytical model of the gas film support and proposed a film stratification theory. The gas film was divided into the near wall layer, the thin layer and the continuous layer, which was proved by the calculation of LAMMPS flow simulation. The velocity slip boundary conditions theory is feasible. Second, the gas film size of the flat plate is at the micron level, which cannot be observed in its flow regimen, only determined by calculation and simulation. This paper proposes a new model and a new tool to analyze gas flow in gas films.

Details

Industrial Lubrication and Tribology, vol. 73 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 7 August 2017

Yi-Sheng Wang, Wei-Long Lee and Tsuen-Ho Hsu

The purpose of this paper is to explore in depth the special context and unique life experience of the online role-playing game and to provide insights regarding an…

Abstract

Purpose

The purpose of this paper is to explore in depth the special context and unique life experience of the online role-playing game and to provide insights regarding an interpretation of the situational context model.

Design/methodology/approach

This study uses netnography, online interviews, and the physical travel of researchers to the field for field participation and observations. The combination of netnography and online interviews combines online and offline studies to achieve more consistency in the data collection, analysis, and other processes. In-person participation in observations makes the research more realistic. The combination of these qualitative methods is helpful in achieving a more comprehensive and accurate research process.

Findings

The findings of the study can be classified into a three-stage situational context approach, which is presented in the form of propositions. Finally, the insight of the situational context model was developed.

Research limitations/implications

This study only focussed on office workers and students in online role-playing game. Therefore, the samples should be extended to other massively multiplayer online games, including different nationalities and professions for comparative analysis and related studies. Through the expansion of the sample size, a representative and stable cyber model can be established.

Originality/value

The theoretical contribution of this study is to establish an interpretation of the situational context model and eight related propositions. The study revealed the mystery of female online role-playing games.

Details

Internet Research, vol. 27 no. 4
Type: Research Article
ISSN: 1066-2243

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Article
Publication date: 19 September 2018

Ya-long Wei, Dan Long, Yao-kuang Li and Xu-sheng Cheng

The purpose of this paper is to build a research model to examine the effects of business planning on the new venture emergence, as well as to examine the moderating…

Abstract

Purpose

The purpose of this paper is to build a research model to examine the effects of business planning on the new venture emergence, as well as to examine the moderating effects of innovativeness of products.

Design/methodology/approach

Four hypotheses are put forward and examined by hierarchical binary logistic regression. The data of this paper are based on the first two waves of data from Chinese Panel Study of Entrepreneurial Dynamics project.

Findings

Results show that engaging in business planning has a positive effect on the new venture emergence, and the timing of business planning does not affect the new venture emergence significantly. This study also finds that the innovativeness of products has a positive moderating effect on the relationship between the timing of business planning and the new venture emergence.

Research limitations/implications

This study has some limitations. The innovativeness of products is measured by a single indicator, which may not completely reflect the meaning of the attribute. Moreover, this study explores new ventures only in the nascent stage.

Practical implications

The study is useful for entrepreneurs to realize the importance of business planning. First, engaging in business planning in early start-up stage is a very valuable activity, because business planning can help new ventures reduce the loss caused by trial and error learning. Second, engaging in business planning is more likely to ensure high innovative products quickly be accepted by the market. Because in the process of new venture emergence, the legitimacy signal to stakeholders can be transmitted and new products can be promoted to get support and recognition from stakeholder through the business plan.

Originality/value

This paper focuses on the early stage of new venture life cycle and the contextual factors to explore the influence of business planning on the new venture emergence under the logic of legitimacy. This paper could enrich business planning research from the perspective of legitimacy theory by inspiring scholars to focus on the differences between new ventures and mature enterprises and to offer proposals of legitimation strategies suitable for new ventures. Meanwhile, this study contributes to the understanding of the contextual factors of business planning. And it discusses the impact of the attribute in business planning on the new venture emergence, which helps scholars to get a deep thought about the value of business planning in entrepreneurial process.

Details

Chinese Management Studies, vol. 12 no. 4
Type: Research Article
ISSN: 1750-614X

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Article
Publication date: 16 October 2018

Shaohua Yang, Wei Long and Fangwei Ning

Velocity slipping model, based on the stratification theory (the film in inflatable support area of aerostatic guide way was divided into near wall layer, thin layer and…

Abstract

Purpose

Velocity slipping model, based on the stratification theory (the film in inflatable support area of aerostatic guide way was divided into near wall layer, thin layer and continuous flow layer in the direction of height), was established, and the model was combined with viscosity changes in each layer.

Design/methodology/approach

Simulated and analyzed by LAMMPS and two-dimensional molecular dynamics method, some relevant conclusions were drawn.

Findings

At a high temperature, viscosity is low, velocity slipping is large and velocity gaps in near-wall layer and thin layer are large. When the temperature is constant, the dimensionless slipping length and Kn number are linear.

Research limitations/implications

The effect of the equivalent viscosity on gas slipping model is proposed. viscosity is smaller, gas velocity slipping is greater, temperature is higher, gas velocity slipping is greater, velocity gap of near wall layer and thin layer is larger. When the temperature is constant, the dimensionless slipping length ls and Kn number are linear.

Originality/value

The global model of lubricating film velocity slipping between plates was established, and mathematical expression of slipping model in each layer, based on the stratification theory, was presented.

Details

Industrial Lubrication and Tribology, vol. 70 no. 8
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 13 August 2019

Ming-Yue Xiong, Liang Zhang, Peng He and Wei-Min Long

The transistor circuit based on Moore's Law is approaching the performance limit. The three-dimensional integrated circuit (3-D IC) is an important way to implement More…

Abstract

Purpose

The transistor circuit based on Moore's Law is approaching the performance limit. The three-dimensional integrated circuit (3-D IC) is an important way to implement More than Moore. The main problems in the development of 3-D IC are Joule heating and stress. The stresses and strains generated in 3-D ICs will affect the performance of electronic products, leading to various reliability issues. The intermetallic compound (IMC) joint materials and structures are the main factors affecting 3-D IC stress. The purpose of this paper is to optimize the design of the 3-D IC.

Design/methodology/approach

To optimize the design of 3-D IC, the numerical model of 3-D IC was established. The Taguchi experiment was designed to simulate the influence of IMC joint material, solder joint array and package size on 3-D IC stress.

Findings

The simulation results show that the solder joint array and IMC joint materials have great influence on the equivalent stress. Compared with the original design, the von Mises stress of the optimal design was reduced by 69.96 per cent, the signal-to-noise ratio (S/N) was increased by 10.46 dB and the fatigue life of the Sn-3.9Ag-0.6Cu solder joint was increased from 415 to 533 cycles, indicating that the reliability of the 3-D IC has been significantly improved.

Originality/value

It is necessary to study the material properties of the bonded structure since 3-D IC is a new packaging structure. Currently, there is no relevant research on the optimization design of solder joint array in 3-D IC. Therefore, the IMC joint material, the solder joint array, the chip thickness and the substrate thickness are selected as the control factors to analyze the influence of various factors on the 3-D IC stress and design. The orthogonal experiment is used to optimize the structure of the 3-D IC.

Details

Soldering & Surface Mount Technology, vol. 32 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 17 October 2016

Ching-Tang Hsieh, Hao-Chen Huang and Wei-Long Lee

The basic concept of transaction cost theory is that firms like to conduct transactions in a channel with lower transaction costs. Therefore, the purpose of this paper is…

Abstract

Purpose

The basic concept of transaction cost theory is that firms like to conduct transactions in a channel with lower transaction costs. Therefore, the purpose of this paper is to use the transaction cost perspective to identify which conditions cause companies to choose between outbound open innovation (hierarchy governance) and inbound open innovation (market governance).

Design/methodology/approach

Accordingly, transaction cost economics was used to relate the choice and implementation of open innovation using a sample of 250 electronics and information start-ups in China. Structural equation modeling was used to conduct confirmatory factor analysis to evaluate measurement model, while logistic regression analysis was used to test the hypotheses.

Findings

As expected, the dedicated asset specificity, human asset specificity, behavioral uncertainty, transaction frequency, and small number exchange were positively associated with outbound open innovation.

Originality/value

The contribution of this paper lies in explaining the role played by transaction cost economics in the process of open innovation for start-ups through empirical analysis.

Details

Management Decision, vol. 54 no. 9
Type: Research Article
ISSN: 0025-1747

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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.

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

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Article
Publication date: 1 October 2018

Penggao Zhang, Boqin Gu, Jianfeng Zhou and Long Wei

The purpose of this study is to investigate the hydrodynamic lubrication characteristics of ferrofluid film for spiral groove mechanical seal in external electromagnetic…

Abstract

Purpose

The purpose of this study is to investigate the hydrodynamic lubrication characteristics of ferrofluid film for spiral groove mechanical seal in external electromagnetic field and to analyze the effects of the volume fraction of ferrofluid, parameters of the electromagnetic field, operating parameters and geometrical parameters of mechanical seal on the characteristics of ferrofluid film.

Design/methodology/approach

The relationship between the ferrofluid viscosity and the intensity of external electromagnetic field was established. Based on the Muijderman narrow groove theory, the pressure distribution was calculated with the trial method by trapezoid formula.

Findings

It was found that pressure, average viscosity, average density and opening force of ferrofluid between end faces increase with the increase in intensity of current, volume fraction of ferrofluid, rotating speed, pressure differential and spiral angle; decrease with the increase in temperature; and increase at first and then decrease with the increase in the ratio of groove width to weir and the groove length. All of them reach the maximum value when the ratio of width of groove to weir is 0.7 and the ratio of groove length is 0.6. Leakage of ferrofluid increases with an increase in intensity of current, volume fraction of ferrofluid, rotating speed, pressure differential, spiral angle and ratio of groove length; decreases with an increase in temperature; and increases at first and then decreases with the increase in the ratio of groove width to weir. The tendencies of characteristics of silicone oil are consistent with those of ferrofluid, and the characteristics of silicone oil are smaller than those of ferrofluid under the same condition.

Originality/value

The volume fraction of ferrofluid, rotating speed, spiral angle, ratio of groove width to weir, groove length and temperature have a significant influence on the characteristics of ferrofluid film; however, intensity of current and the pressure differential have slight influence on the characteristics of ferrofluid film. An analytical method for analyzing hydrodynamic lubrication characteristics of ferrofluid film in a spiral groove mechanical seal was proposed based on the Muijderman narrow groove theory.

Details

Industrial Lubrication and Tribology, vol. 70 no. 9
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 January 2005

K. Jeevan, G.A. Quadir, K.N. Seetharamu, I.A. Azid and Z.A. Zainal

To determine the optimal dimensions for a stacked micro‐channel using the genetic algorithms (GAs) under different flow constraints.

Abstract

Purpose

To determine the optimal dimensions for a stacked micro‐channel using the genetic algorithms (GAs) under different flow constraints.

Design/methodology/approach

GA is used as an optimization tool for optimizing the thermal resistance of a stacked micro‐channel under different flow constraints obtained by using the one dimensional (1D) and two dimensional (2D) finite element methods (FEM) and by thermal resistance network model as well (proposed by earlier researcher). The 2D FEM is used to study the effect of two dimensional heat conduction in the micro‐channel material. Some parametric studies are carried out to determine the resulting performance of the stacked micro‐channel. Different number of layers of the stacked micro‐channel is also investigated to study its effect on the minimum thermal resistance.

Findings

The results obtained from the 1D FEM analysis compare well with those obtained from the thermal resistance network model. However, the 2D FEM analysis results in lower thermal resistance and, therefore, the importance of considering the conduction in two dimensions in the micro‐channel is highlighted.

Research limitations/implication

The analysis is valid for constant properties fluid and for steady‐state conditions. The top‐most surfaces as well as the side surfaces of the micro‐channel are considered adiabatic.

Practical implications

The method is very useful for practical design of micro‐channel heat‐sinks.

Originality/value

FEM analyses of stacked micro‐channel can be easily implemented in the optimization procedure for obtaining the dimensions of the stacked micro‐channel heat‐sinks for minimum thermal resistance.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 15 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 4 April 2008

Berna Kirkulak

The purpose of this paper is to examine initial and long‐run returns of Japanese IPOs in particular venture capital (VC)‐backed and non‐VC‐backed. The main research focus…

Abstract

Purpose

The purpose of this paper is to examine initial and long‐run returns of Japanese IPOs in particular venture capital (VC)‐backed and non‐VC‐backed. The main research focus is on the performance of VC‐backed companies.

Design/methodology/approach

This paper presents a comprehensive long‐run performance analysis. As such, it provides evidence using two performance methods: cumulative abnormal returns (CARs) and buy‐and‐hold return (BHARs). This paper uses updated data from 1998 through 2001 and presents a deeper understanding for the long‐run returns of Japanese IPOs.

Findings

The findings show that there is no statistically significant difference in the initial returns of VC‐backed and non‐VC‐backed companies. The evidence is inconsistent with the VC certification hypothesis that venture capitalists certify the true value of the firm and therefore reduce underpricing. Further, Japanese IPOs underperform in the long‐run. The fads hypothesis is applicable to explain the poor long‐run performance. The results suggest that although VC‐backed companies have high initial returns, they perform significantly worse over a three‐year time horizon than non‐VC‐backed companies.

Research limitations/implications

An examination of the lock‐up agreements is necessary to understand negative returns. The results of this paper provide a good starting point for such a study.

Practical implications

This paper highlights the stock returns of VC‐backed and non‐VC‐backed companies. It is hoped that investors and academics will benefit from the outcome of the current paper.

Originality/value

To date, there is no comprehensive study on the Japanese IPO market applying both CAR and BHAR long‐run measurements. This paper applies both measurements. Further, this is the first study of the long‐run performance of Japanese firms going public in Mothers and in Hercules stock markets.

Details

International Journal of Managerial Finance, vol. 4 no. 2
Type: Research Article
ISSN: 1743-9132

Keywords

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