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Article
Publication date: 18 February 2019

Fen Peng, Wensheng Liu, Yunzhu Ma, Chaoping Liang, Yufeng Huang and Siwei Tang

To explore substitutes for traditional Sn-Pb solder, Sn-20In-2.8Ag was considered because of its appropriate melting temperature, good reliability and high ductility at…

Abstract

Purpose

To explore substitutes for traditional Sn-Pb solder, Sn-20In-2.8Ag was considered because of its appropriate melting temperature, good reliability and high ductility at less than 100°C. However, the mechanical properties of Sn-20In-2.8Ag were not satisfactory. The reason for the poor mechanical properties of the Sn-20In-2.8Ag/Cu joint was revealed, and a way to solve the problem was found.

Design/methodology/approach

The microstructure evolution, characteristics of melting and solidification and joining performance with Cu were investigated using scanning electron microscopy (SEM), electron probe microanalysis, differential scanning calorimetry (DSC) and mechanical testing.

Findings

SEM results showed that the microstructure of Sn-20In-2.8Ag was composed of coarse dendritic Ag2In and γ phases, with Ag2In distributed at the grain boundaries. DSC measurements revealed that small amount of low temperature eutectic reaction, L → Ag2In + β + γ, occurred at 112.9°C. This reaction was caused by the segregation of indium, which is a process that has a strong driving force. In the lap-shear testing, a crack propagated along the grain boundary of the solder, and failure showed an intergranular fracture. This failure was connected with the three-phase eutectic and coarse Ag2In. Thus, to improve the mechanical properties, segregation of indium should be reduced and coarsening of Ag2In should be prevented.

Originality/value

The reason for the unsatisfactory mechanical properties of Sn-20In-2.8Ag was revealed via microstructural observations and solidification analysis, and the way to solve this problem was found.

Details

Soldering & Surface Mount Technology, vol. 31 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 18 February 2019

Fen Peng, Wensheng Liu, Yufeng Huang, Siwei Tang, Chaoping Liang and Yunzhu Ma

The purpose of this study is to develop a monolayer surface coating of stearic acid on Sn-Ag-Cu solder powder to limit oxidation.

Abstract

Purpose

The purpose of this study is to develop a monolayer surface coating of stearic acid on Sn-Ag-Cu solder powder to limit oxidation.

Design/methodology/approach

Stearic acid was adsorbed onto Sn-Ag-Cu solder powder through liquid-phase adsorption. The isotherm of adsorption was measured and then the microstructure of coated powder was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy.

Findings

The adsorption isotherm of stearic acid on the powder was “H” type, which revealed the layer-by-layer adsorption on non-porous surface. When the concentration of solution was in the range of 0.001-0.006 mol/L, with an adsorption amount of 0.12 ± 0.1 mg/g, monolayer stearic acid covered the solder powder completely. Uniform and integrated self-assembled monolayer coating was formed through hydrogen bonds between the oxygen ions in surface lattice of Sn3.0Ag0.5Cu solder powder and the —O—H hydroxyl group of stearic acid. The maximum angle of stability of coated powder also reduced by 2.87° compared with that of non-coated powder. The increase rate of oxygen content of coated powder was much slower than that of non-coated powder when they were exposed to humid air.

Originality/value

As a result, oxidation of fine solder powder was effectively limited. Essentially, this method can also be applied to the coating of other types of solder powder and has reference significance to other coating by liquid-phase method.

Details

Soldering & Surface Mount Technology, vol. 31 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 12 February 2021

Shijie Dai, Shining Li, Wenbin Ji, Zhenlin Sun and Yufeng Zhao

This study aims to realize the constant force grinding of automobile wheel hub.

Abstract

Purpose

This study aims to realize the constant force grinding of automobile wheel hub.

Design/methodology/approach

A force control strategy of backstepping + proportion integration differentiation (PID) is proposed. The grinding end effector is installed on the flange of the robot. The robot controls the position and posture of the grinding end actuator and the grinding end actuator controls the grinding force output. First, the modeling and analysis of the grinding end effector are carried out, and then the backstepping + PID method is adopted to control the grinding end effector to track the expected grinding force. Finally, the feasibility of the proposed method is verified by simulation and experiment.

Findings

The simulation and experimental results show that the backstepping + PID strategy can track the expected force quickly, and improve the dynamic response performance of the system and the quality of grinding and polishing of automobile wheel hub.

Research limitations/implications

The mathematical model is based on the pneumatic system and ideal gas, and ignores the influence of friction in the working process of the cylinder, so the mathematical model proposed in this study has certain limitations. A new control strategy is proposed, which is not only used to control the grinding force of automobile wheels, but also promotes the development of industrial control.

Social implications

The automatic constant force grinding of automobile wheel hub is realized, and the manpower is liberated.

Originality/value

First, the modeling and analysis of the grinding end effector are carried out, and then the backstepping + PID method is adopted to control the grinding end effector to track the expected grinding force. The nonlinear model of the system is controlled by backstepping method, and in the process, the linear system composed of errors is obtained, and then the linear system is controlled by PID to realize the combination of backstepping and PID control.

Details

Industrial Robot: the international journal of robotics research and application, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0143-991X

Keywords

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Article
Publication date: 10 July 2017

Chaoran Liu, Yufeng Su, Jinzhao Yue, Junjie Wang, Weiwei Xia, Dongxue Li, Wen Wang, Pan Wang and Zhiyong Duan

A self-adaptive piston is designed for the compressional gas cushion press nanoimprint lithography system. It avoids the lube pollution and high wear of traditional piston.

Abstract

Purpose

A self-adaptive piston is designed for the compressional gas cushion press nanoimprint lithography system. It avoids the lube pollution and high wear of traditional piston.

Design/methodology/approach

The self-adaptive piston device consists of symmetrical piston bodies, piston rings and other parts. The two piston bodies are linked by a ball-screw. The locking nut adjusts the distance between two piston bodies to avoid the piston rings from being stuck. The piston rings are placed between two piston bodies.

Findings

The simulation results based on COMSOL indicate that cylinder vibration caused by self-adaptive piston is 15.9 times smaller than the one caused by a traditional piston.

Originality/value

The self-adaptive piston is superior to the traditional piston in decreasing cylinder vibration.

Details

Industrial Lubrication and Tribology, vol. 69 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 6 August 2019

Yannapol Sriphutkiat and Yufeng Zhou

The capability of microparticle/objects patterning in the three-dimensional (3D) printing structure could improve its performance and functionalities. This paper aims to…

Abstract

Purpose

The capability of microparticle/objects patterning in the three-dimensional (3D) printing structure could improve its performance and functionalities. This paper aims to propose and evaluate a novel acoustic manipulation approach.

Design/methodology/approach

A novel method to accumulate the microparticles in the cylindrical tube during the 3D printing process is proposed by acoustically exciting the structural vibration of the cylindrical tube at a specific frequency, and subsequently, focusing the 50-μm polystyrene microparticles at the produced pressure node toward the center of the tube by the acoustic radiation force. To realize this solution, a piezoceramic plate was glued to the outside wall of a cylindrical glass tube with a tapered nozzle. The accumulation of microparticles in the tube and printing structure was monitored microscopically and the accumulation time and width were quantitatively evaluated. Furthermore, the application of such technology was also evaluated in the L929 and PC-12 cells suspended in the sodium alginate and gelatin methacryloyl.

Findings

The measured location of pressure and the excitation frequency of the cylindrical glass tube (172 kHz) agreed quite well with our numerical simulation (168 kHz). Acoustic excitation could effectively and consistently accumulate the microparticles. It is found that the accumulation time and width of microparticles in the tube increase with the concentration of sodium alginate and microparticles in the ink. As a result, the microparticles are concentrated mostly in the central part of the printing structure. In comparison to the conventional printing strategy, acoustic excitation could significantly reduce the width of accumulated microparticles in the printing structure (p < 0.05). In addition, the possibility of high harmonics (385 and 657 kHz) was also explored. L929 and PC-12 cells suspended in the hydrogel can also be accumulated successfully.

Originality/value

This paper proves that the proposed acoustic approach is able to increase the accuracy of printing capability at a low cost, easy configuration and low power output.

Details

Rapid Prototyping Journal, vol. 25 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 26 January 2021

Yufeng Xia and Peisen Liu

Bank financing is an important external financing source for firm research and development (R&D) investment. This study aims to use an exponential quadratic specification…

Abstract

Purpose

Bank financing is an important external financing source for firm research and development (R&D) investment. This study aims to use an exponential quadratic specification to investigate the effect of bank competition on firm R&D investment and its underlying mechanisms. Moreover, this study checks bank competition’s heterogeneous effects on firm R&D investment.

Design/methodology/approach

Based on data of Chinese manufacturing firms and bank branches, this study uses the Tobit estimator, instrumental variable method and Heckman two-step approach to test the relationship between bank competition and firm R&D investment.

Findings

The results show robustness evidence of an inverted-U relationship between bank competition and firm R&D investment. Specifically, increases in bank competition promote firm R&D investment until bank competition reaches the turning point and reduce firm R&D investment after crossing the turning point. Financing costs and financial constraints can explain the inverted-U relationship between bank competition and firm R&D investment. Heterogeneity examinations reveal that R&D investment is more sensitive to bank competition in non-state-owned enterprises, small firms and high-tech firms.

Originality/value

This study contributes to the literature on the relationship between bank competition and firm innovation. The authors investigate the heterogeneity of R&D investment influenced by bank competition and depict the economic effects brought by bank competition. This study sheds light on the real effects of bank competition and the determinants of firm R&D investment in transition economies. The conclusions provide empirical evidence for reducing credit discrimination and improving capital allocation efficiency in developing countries.

Details

Chinese Management Studies, vol. 15 no. 3
Type: Research Article
ISSN: 1750-614X

Keywords

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Article
Publication date: 29 April 2021

Yuan-pei Kuang, Jia-li Yang and Meseret-Chanie Abate

The multidimensional effects of farmland transfer in China have been profoundly unstudied. The purpose of this paper is to provide insights on the effects of the…

Abstract

Purpose

The multidimensional effects of farmland transfer in China have been profoundly unstudied. The purpose of this paper is to provide insights on the effects of the intermediary role of agricultural total factor productivity (TFP) of farmland transfer on agricultural economic growth in China.

Design/methodology/approach

Based on the agricultural data of 30 provinces in China over the period 2005–2018, this paper uses the intermediary effect model to test the relationship between farmland transfer, agricultural TFP and agricultural economic growth. This paper employed an intermediary effect test model to investigate the intermediary role of agricultural TFP in the influence of farmland transfer on agricultural economic growth.

Findings

The findings indicated that farmland transfer has a significant effect on promoting agricultural economic growth. There is a significant “inverted U-shaped” relationship between farmland transfer and agricultural TFP. The sample value of 84.3% of farmland transfers in China is still within the TFP promoting effect range. In addition, farmland transfer has an indirect impact on agricultural economic growth through the channel of agricultural TFP. Agricultural TFP plays a significant intermediary role, but the effect is relatively low

Originality/value

This paper is the first to provide fundamental evidence on the impact of farmland transfers on agricultural economic growth in China, driven by agricultural TFP as an intermediary factor. Agricultural TFP can reduce the involution effect of farmland transfer and promote an indirect effect on agricultural economic growth.

Details

China Agricultural Economic Review, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1756-137X

Keywords

Content available
Article
Publication date: 1 January 2013

Abstract

Details

Journal of Manufacturing Technology Management, vol. 24 no. 1
Type: Research Article
ISSN: 1741-038X

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Article
Publication date: 1 October 2006

Stephen L. Morgan

Management is a “hot field” in China, yet little has been written in English about the history of management in China. Contrary to contemporary management literature, the…

Abstract

Purpose

Management is a “hot field” in China, yet little has been written in English about the history of management in China. Contrary to contemporary management literature, the paper aims to show that Chinese entrepreneurs and managers were exposed to modern management ideas from the early twentieth century. The paper is an initial exploration of the transfer of managerial knowledge to China, especially Scientific Management, during the interwar period.

Design/methodology/approach

Draws on Chinese journal articles and books from 1910‐1930s, supplemented with archive materials and secondary sources in Chinese and English.

Findings

Chinese industrialists, officials and academics were attracted to Taylor's ideas of scientific management during the 1920s and 1930s, which were experimented with on a wider scale than is commonly realized. The interest in “new” management extended beyond industrialists and industry officials to reportage in the popular press.

Research limitations/implications

Future research should consider first how new ideas about management and organization were implemented on the shopfloor in individual Chinese enterprises, and second examine the role of social networks constituted by native place, industry ties and professional association membership in the diffusion of managerial ideas among the Chinese business elite of the period.

Originality/value

The paper shows that the transfer to China of modern management as an ideas system was not a recent phenomenon, but part of a century‐long process of transfer and adaptation of western management theory and practice.

Details

Journal of Management History, vol. 12 no. 4
Type: Research Article
ISSN: 1751-1348

Keywords

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Article
Publication date: 25 January 2013

Sifeng Liu, Yingjie Yang, Ying Cao and Naiming Xie

The purpose of this paper is to review systematically the research of grey relation analysis (GRA) models.

Abstract

Purpose

The purpose of this paper is to review systematically the research of grey relation analysis (GRA) models.

Design/methodology/approach

Three different approaches, the springboard to build a GRA model, the angle of view in modelling, and the dimension of objects, are analysed, respectively.

Findings

The GRA models developed from the models based on relation coefficients of each point in the sequences in early days to the generalized GRA models based on integral or overall perspective. It evolved from the GRA models which measure similarity based on nearness, into the models which consider similarity and nearness, respectively. The objects of the research advanced from the analysis of relationship among curves to that among curved surfaces, and further to the analysis of relationship in three‐dimensional space and even the relationship among super surfaces in n‐dimensional space.

Originality/value

The further research on GRA models is proposed. One is about the property of GRA model. An in‐depth knowledge about the properties of GRA model will help people to understand its function, applicable area and requirements for modelling. The other one is about the extension of research object system. The object to be analysed should be extended from the common sequence of real numbers to grey numbers, vectors, matrices, and even multi‐dimensional matrices, etc.

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