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Article

Min Wu and Xiangyu Su

Because of the complexity of relationship between surface tension and its decisive factors, such as temperature, concentration, electronic density, molar atomic volume and…

Abstract

Purpose

Because of the complexity of relationship between surface tension and its decisive factors, such as temperature, concentration, electronic density, molar atomic volume and electro-negativity, a reasonable predicting model of surface tension of Sn-based solder alloys has not been developed yet. The paper aims to address the surface tension issue that has to be considered if the new lead free solder will be applied for electronics.

Design/methodology/approach

Using an artificial neural network (ANN) model with back-propagation (BP) algorithm, the surface tension for Sn-based binary solder alloys was simulated, and the comparison between the simulating results and data from experiments and literatures was analyzed as well. In addition, the relationship between surface tension and its decisive factors would be discussed based on the ANN and orthogonal design methods.

Findings

It is shown that the predicting model of surface tension of Sn-based solder alloys is constructed according to the BP–ANN theory, and the predicted value from the BP–ANN is in excellent agreement with the experimental results. The surface tension of Sn-based solders is determined by five factors, i.e. temperature, concentration, electronic density, molar atomic volume and electro-negativity. Among of the factors, molar atomic volume is major factor, and the order of degree of influence on surface tension is molar atomic volume > electro-negativity > electronic > density > concentration > temperature. Moreover, a simply reasonable equation is proposed to estimate the surface tension for Sn-based solders.

Originality/value

The five decisive factors of surface tension for Sn-based binary solder alloys have been analyzed theoretically, and a reasonable model of surface tension for Sn-based binary solder alloys is proposed as well. It is shown that ANN theory will be applied well to simulate the surface tension of Sn-based lead free solder.

Details

Soldering & Surface Mount Technology, vol. 28 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

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Article

Min Wu and Bailin Lv

Viscosity is an important basic physical property of liquid solders. However, because of the very complex nonlinear relationship between the viscosity of the liquid…

Abstract

Purpose

Viscosity is an important basic physical property of liquid solders. However, because of the very complex nonlinear relationship between the viscosity of the liquid ternary Sn-based lead-free solder and its determinants, a theoretical model for the viscosity of the liquid Sn-based solder alloy has not been proposed. This paper aims to address the viscosity issues that must be considered when developing new lead-free solders.

Design/methodology/approach

A BP neural network model was established to predict the viscosity of the liquid alloy and the predicted values were compared with the corresponding experimental data in the literature data. At the same time, the BP neural network model is compared with the existing theoretical model. In addition, a mathematical model for estimating the melt viscosity of ternary tin-based lead-free solders was constructed using a polynomial fitting method.

Findings

A reasonable BP neural network model was established to predict the melt viscosity of ternary tin-based lead-free solders. The viscosity prediction of the BP neural network agrees well with the experimental results. Compared to the Seetharaman and the Moelwyn–Hughes models, the BP neural network model can predict the viscosity of liquid alloys without the need to calculate the relevant thermodynamic parameters. In addition, a simple equation for estimating the melt viscosity of a ternary tin-based lead-free solder has been proposed.

Originality/value

The study identified nine factors that affect the melt viscosity of ternary tin-based lead-free solders and used these factors as input parameters for BP neural network models. The BP neural network model is more convenient because it does not require the calculation of relevant thermodynamic parameters. In addition, a mathematical model for estimating the viscosity of a ternary Sn-based lead-free solder alloy has been proposed. The overall research shows that the BP neural network model can be well applied to the theoretical study of the viscosity of liquid solder alloys. Using a constructed BP neural network to predict the viscosity of a lead-free solder melt helps to study the liquid physical properties of lead-free solders that are widely used in electronic information.

Details

Soldering & Surface Mount Technology, vol. 32 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

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Article

Zheng-Xin Wang, Ji-Min Wu, Chao-Jun Zhou and Qin Li

Seasonal fluctuation interference often affects the relational analysis of economic time series. The main purpose of this paper is to propose a new grey relational model…

Abstract

Purpose

Seasonal fluctuation interference often affects the relational analysis of economic time series. The main purpose of this paper is to propose a new grey relational model for relational analysis of seasonal time series and apply it to identify and eliminate the influence of seasonal fluctuation of retail sales of consumer goods in China.

Design/methodology/approach

First, the whole quarterly time series is divided into four groups by data grouping method. Each group only contains the time series data in the same quarter. Then, the new series of four-quarters are used to establish the grey correlation model and calculate its correlation coefficient. Finally, the correlation degree of factors in each group of data was calculated and sorted to determine its importance.

Findings

The data grouping method can effectively reflect the correlation between time series in different quarters and eliminate the influence of seasonal fluctuation.

Practical implications

In this paper, the main factors influencing the quarterly fluctuations of retail sales of consumer goods in China are explored by using the grouped grey correlation model. The results show that the main factors are different from quarter to quarter: in the first quarter, the main factors are money supply, tax and per capita disposable income of rural residents. In the second quarter are money supply, fiscal expenditure and tax. In the third quarter are money supply, fiscal expenditure and per capita disposable income of rural residents. In the fourth quarter are money supply, fiscal expenditure and tax.

Originality/value

This paper successfully realizes the application of grey relational model in quarterly time series and extends the applicable scope of grey relational model.

Details

Grey Systems: Theory and Application, vol. 10 no. 2
Type: Research Article
ISSN: 2043-9377

Keywords

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Article

Kesheng Lin, Jie Liu, Jia-Min Wu, Yunlong Sun, Feng Li, Yan Zhou and Yusheng Shi

The main cause of aseptic inflammation after an in vivo implantation is that Poly(L-lactide) (PLLA) and Poly(D-lactide) have a slower degradation and absorption rate…

Abstract

Purpose

The main cause of aseptic inflammation after an in vivo implantation is that Poly(L-lactide) (PLLA) and Poly(D-lactide) have a slower degradation and absorption rate, while Poly(D, L-lactide) (PDLLA) has a much faster degradation rate than PLLA because of its amorphous structure. Also, the hydrolyzate of Hydroxyapatite (HA) is alkaline, which can neutralize local tissue peracid caused by hydrolysis of Polylactic acid.

Design/methodology/approach

In this study, the selective laser sintering (SLS) technique was chosen to prepare bone scaffolds using nano-HA/PDLLA composite microspheres, which were prepared by the solid-in-oil-in-water (S/O/W) method. First, the SLS parameters range of bulk was determined by the result of a single-layer experiment and the optimized parameters were then obtained by the orthogonal experiment. The tensile property, hydrophobicity, biocompatibility, biological toxicity and in vitro degradation of the samples with optimized SLS parameters were characterized.

Findings

As a result, the samples showed a lower tensile strength because of the many holes in their interior, which was conducive to better cell adhesion and nutrient transport. In addition, the samples retained their inherent properties after SLS and the hydrophobicity was improved after adding nano-HA because of the OH group. Furthermore, the samples showed good biocompatibility with the large number of cells adhering to the material through pseudopods and there was no significant difference between the pure PDLLA and 10% HA/PDLLA in terms of biological toxicity. Finally, the degradation rate of the composites could be tailored by the amount of nano-HA.

Originality/value

This study combined the S/O/W and SLS technique and provides a theoretical future basis for the preparation of drug-loaded microsphere scaffolds through SLS using HA/PDLLA composites.

Details

Rapid Prototyping Journal, vol. 26 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

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Article

Tso-Jen Chen and Chi-Min Wu

This study aims to explore the high turnover intention issue in Taiwan’s tourist hotel industry. Due to a lack of empirical research regarding front-line employees…

Abstract

Purpose

This study aims to explore the high turnover intention issue in Taiwan’s tourist hotel industry. Due to a lack of empirical research regarding front-line employees’ psychological contract breach perceptions in tourism literature, this study develops an integrated model to examine the causal relationship among transformational leadership behaviors, leader–member exchange (LMX), psychological contract breach and turnover intentions.

Design/methodology/approach

Data from the 226 frontline employees in Taiwan’s tourist hotel industry were employed to examine the proposed hypotheses by using a series of structural equation modeling analyses.

Findings

Statistic results revealed that transformational leadership behaviors influence LMX and LMX in turn influences psychological contract breach, which consequently leads to lower turnover intention.

Practical implication

The results of this study suggest that hospitality organizations should recruit individuals who have the potential to exhibit transformational leadership skills, along with designing leadership training programs for middle- and high-level managers.

Originality/value

This study provides hospitality organization leaders with the necessary information to formulate a beneficial relationship with their front-line employees, which, in turn, weakens their perception of psychological contract breaches and reduces their willingness to leave the organization.

Details

International Journal of Contemporary Hospitality Management, vol. 29 no. 7
Type: Research Article
ISSN: 0959-6119

Keywords

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Book part

Yanqin Fan and Sang Soo Park

In this paper, we study partial identification of the distribution of treatment effects of a binary treatment for ideal randomized experiments, ideal randomized…

Abstract

In this paper, we study partial identification of the distribution of treatment effects of a binary treatment for ideal randomized experiments, ideal randomized experiments with a known value of a dependence measure, and for data satisfying the selection-on-observables assumption, respectively. For ideal randomized experiments, (i) we propose nonparametric estimators of the sharp bounds on the distribution of treatment effects and construct asymptotically valid confidence sets for the distribution of treatment effects; (ii) we propose bias-corrected estimators of the sharp bounds on the distribution of treatment effects; and (iii) we investigate finite sample performances of the proposed confidence sets and the bias-corrected estimators via simulation.

Details

Nonparametric Econometric Methods
Type: Book
ISBN: 978-1-84950-624-3

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Book part

Michael O’Regan and Jaeyeon Choe

As its market and society open up, China has transformed itself from a closed agrarian socialist economy to an urban state and an economic force. This has released…

Abstract

As its market and society open up, China has transformed itself from a closed agrarian socialist economy to an urban state and an economic force. This has released accumulated tourism demand, led to the development of a diversified industry, and the spread of university and vocational courses in this field. However, the industry faces challenges to recruit and retain staff, with tourism education in higher education blamed for the shortfall in numbers and quality of candidates with suitable purpose, knowledge, and passion to serve. This chapter provides a background to the development of and problems facing tourism education in China, and suggests how to support student engagement and hence the future workforce.

Details

Tourism Education: Global Issues and Trends
Type: Book
ISBN: 978-1-78350-997-3

Keywords

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Article

Wu Min and Low Sui Pheng

To develop just‐in‐time (JIT) purchasing threshold value (JPTV) models for ready mixed concrete (RMC) suppliers to decide whether or not to switch from an economic order…

Abstract

Purpose

To develop just‐in‐time (JIT) purchasing threshold value (JPTV) models for ready mixed concrete (RMC) suppliers to decide whether or not to switch from an economic order quantity (EOQ) approach to a JIT purchasing approach for the purchase of their raw materials, when a price discount is offered.

Design/methodology/approach

The existing economic order quantity (EOQ) with a price discount versus the JIT purchasing cost comparative models neglect some important cost components under the inventory management systems, for example, the out‐of‐stock costs and the impact of inventory policy on product quality and production flexibility. In addition, these models do not empirically study the capability of an inventory facility to hold the EOQ‐JIT cost indifference point's amount of inventory. These models suggest that the JIT purchasing approach is always preferred to the EOQ approach when the JIT purchasing approach can capitalize on physical plant space reduction. The JPTV models developed in this study overcome the two limitations of the existing EOQ and JIT purchasing cost comparative models.

Findings

By developing the JPTV models, this study suggests that the theoretical advantages of JIT purchasing may have been overstated.

Originality/value

The field studies conducted in the RMC industries in Chongqing, China and Singapore supported the propositions in this study. The JPTV models, if adopted, would help to enhance performance in the RMC industries in other cities as well.

Details

International Journal of Productivity and Performance Management, vol. 54 no. 4
Type: Research Article
ISSN: 1741-0401

Keywords

Content available
Article

Hung-Che Wu and Ching-Chan Cheng

The purpose of this paper is to explore the structural relationship between green persistence intentions and their seven drivers – green authenticity, green perceptual…

Abstract

Purpose

The purpose of this paper is to explore the structural relationship between green persistence intentions and their seven drivers – green authenticity, green perceptual evaluation, green co-creation, green experiential memorability, green experiential satisfaction, green passionate love and green need for cognition in a green hotel context.

Design/methodology/approach

The data used in this study were based on a sample of 589 customers staying at one green hotel in New Taipei City of Taiwan. The predicted relationship was tested using the structural equation modeling and the hierarchical regression analysis.

Findings

The results indicate that green perceptual evaluation, green co-creation and green experiential memorability influence green experiential satisfaction. Green passionate love is influenced by green experiential satisfaction. Green need for cognition moderates the effect of green experiential satisfaction on green persistence intentions. Green persistence intentions are influenced by green experiential satisfaction and green passionate love.

Practical implications

To increase green authenticity, green perceptual evaluation, green co-creation, green experiential memorability, green experiential satisfaction, green passionate love, green need for cognition and green persistence intentions, the study findings will help green hotels to develop and implement market-orientated product and/or service strategies.

Originality/value

This paper provides data that lead to a better understanding of the relationships among green authenticity, green perceptual evaluation, green co-creation, green experiential memorability, green experiential satisfaction, green passionate love, green need for cognition and green persistence intentions in a green hotel context.

Details

Asia Pacific Journal of Marketing and Logistics, vol. 31 no. 1
Type: Research Article
ISSN: 1355-5855

Keywords

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Article

This article has been withdrawn as it was published elsewhere and accidentally duplicated. The original article can be seen here: 10.1108/00022660410545483. When citing…

Abstract

This article has been withdrawn as it was published elsewhere and accidentally duplicated. The original article can be seen here: 10.1108/00022660410545483. When citing the article, please cite: Zhe-Min Wu, Chi Chen, Gao-Lian Liu, (2004), “Multipoint inverse shape design of airfoils based on variable-domain variational principle”, Aircraft Engineering and Aerospace Technology, Vol. 76 Iss: 4, pp. 376-38.

Details

Aircraft Engineering and Aerospace Technology, vol. 76 no. 5
Type: Research Article
ISSN: 0002-2667

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