F. Guo, J. Lee and K.N. Subramanian
In an attempt to improve service life of lead‐free Sn‐based electronic solder joints, compatible reinforcements were introduced by in‐situ and mechanical mixing methods. The…
Abstract
In an attempt to improve service life of lead‐free Sn‐based electronic solder joints, compatible reinforcements were introduced by in‐situ and mechanical mixing methods. The reinforcements affect the steady‐state creep rate and the strain for the onset of tertiary creep of the solder joints. However, neither of these parameters, when considered alone, can be used for evaluating the reliability of solder joints. The Larson‐Miller parameter, and a new parameter proposed in the paper, can incorporate test parameters to arrive at a reliability prediction methodology. The role of these reinforcements in homogenising creep strain within the joint is analysed. The observed creep behaviour of these composite solders is discussed on the basis of interfacial bonding strength between the reinforcement and the solder matrix.
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Yunlu Du, Yunkai Huang, Baocheng Guo, Zakarya Djelloul-Khedda, Frédéric Dubas and Hajime Igarashi
Compared with the time-consuming numerical method and the complex lumped parameter thermal network method to solve the steady-state heat distribution of the permanent magnet (PM…
Abstract
Purpose
Compared with the time-consuming numerical method and the complex lumped parameter thermal network method to solve the steady-state heat distribution of the permanent magnet (PM) linear motor, there is no analytical method based on the thermal partial differential equations. This paper aims to propose a two-dimensional (2-D) analytical model for predicting the steady-state temperature distribution of PM linear motors to improve the prediction accuracy and speed up the calculation.
Design/methodology/approach
Based on the complex Fourier series theory and Cauchy’s product theorem, this paper presents for the first time a general analytical solution for 2-D temperature field in Cartesian coordinates. Then, by combining the electromagnetic field finite element model (FEM), the copper loss, iron loss and PM eddy current loss are used as the heat sources of the thermal analytical model. Finally, the solution to the temperature field is obtained by solving the system equations under boundary and interface conditions.
Findings
The analytical results are in good agreement with those from the thermal FEM, and the calculation speed is significantly faster than that of the thermal FEM.
Originality/value
The multilayer model proposed in this paper can consider heat conduction, convection and radiation. It is not only suitable for PM linear motors but also has significant application value for the thermal analysis of electromagnetic devices modeled in 2-D Cartesian coordinates.
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Zhanchao Wang, Fei Guo, Ying Liu, Xiangfeng Liu and Yuming Wang
This aim of this paper has been to investigate the squeeze effect of a water-lubricated tilting-pad thrust bearing during start-up and shut-down periods.
Abstract
Purpose
This aim of this paper has been to investigate the squeeze effect of a water-lubricated tilting-pad thrust bearing during start-up and shut-down periods.
Design/methodology/approach
In this paper a numerical model with a squeeze and slippage effect was adopted to analyse the asymmetry characteristic of a tilting-pad thrust bearing during start-up and shut-down periods. A test rig was built to verify numerical results, which were a combined measurement method in which acceleration sensor and torque sensor were used simultaneously to determine the angle change of the thrust pad.
Findings
It was found that as the velocity gradient increased, the difference of the minimum dimensionless film Hmin could be ignored in the start-up process. But in the shut-down process, as the velocity gradient increased, the value of Hmin also increased, which showed that there was an asymmetry characteristic of the tilting bearing in two processes. This phenomenon was verified by measuring the friction torque curve in the test.
Originality/value
The results of the studies demonstrated that the velocity gradient could be designed to reduce the friction of the thrust bearing, which would be beneficial to the working life of the tilting-pad thrust bearing.
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Abstract
Purpose
The purpose of this paper is to improve the anti‐sedimentation of the acrylic resin containing long afterglow phosphors (SrMgAl4O8:Eu2+, Dy3+).
Design/methodology/approach
The phosphors were first modified by the vinylsilane coupling agent MPS (3‐(methacryloxypropyl)‐trimethoxysilane). Then, the acrylic resin containing modified phosphors was synthesised by in situ polymerisation. Meanwhile, the compared blend sample was prepared by pure acylic resin with no modified phosphors in the same content. When the two resins were coated on glass, the films were characterised by ATR‐FTIR, SEM and TGA. The sedimentation performances of liquid resins were also observed.
Findings
Results showed that anti‐sedimentation of acrylic resin with phosphors by in situ polymerisation was enhanced greatly, because the phosphors have been connected with the macromolecule chain, and dispersed homogeneously with no aggregation, so preventing its sedimentation.
Research limitations/implications
Researchers are encouraged to test the proposed method and enhance the anti‐sedimentation further.
Practical implications
This method provides an idea to solve the problem of anti‐sedimentation in luminescent paint containing long afterglow phosphors in practical production and application.
Originality/value
This paper introduced the in situ polymerisation to enhance the anti‐sedimentation of acrylic resin containing long afterglow phosphors and it can be applied also to other inorganic powders.
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Abstract
Purpose
The purpose of this paper is to report on a study which aims to improve the compatibility of the long afterglow phosphors SrMgAl4O8:Eu2+, Dy3+with organic matrix, including its water resistance.
Design/methodology/approach
The phosphors were modified by the lauric acid‐based Al‐Zr coupling agent (CA). Then, they were characterised by attenuated total reflection fourier transform infrared (ATR‐FTIR), pH and electric conductivity in water, scanning electron microscope (SEM), contact angle and fluorescence decay curves before and after modification.
Findings
The pH and electric conductivity displayed the improved water resistance, as the Al‐Zr CA addition increased, and the minimum contact angle with resin decreased from 68.3 to 40.3°C, which showed that the compatibility with organic matrix was enhanced significantly. The afterglow luminous properties were unimpaired.
Research limitations/implications
The researchers are encouraged to test the proposed method and enhance the compatibility further.
Practical implications
This method will extend the applications of phosphors in the paint, coatings, ink and plastics industry.
Originality/value
This paper introduces the lauric acid‐based Al‐Zr CA to modify the luminescent pigments of long afterglow phosphors; it can be also applied to other inorganic powders.
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Rasha Najib Al-Jabali, Norasnita Ahmad and Saleh F.A. Khatib
The purpose of this study is to review the literature on the adoption determinants of mobile health (M-health) applications for health behavior change following a systematic…
Abstract
Purpose
The purpose of this study is to review the literature on the adoption determinants of mobile health (M-health) applications for health behavior change following a systematic methodology.
Design/methodology/approach
This review systematically identified 134 peer-reviewed studies out of 10,687 from Scopus, Web of Science, PubMed and the Association for Computing Machinery (ACM) published between 2010 and 2021. This review used a thematic analysis to produce the main themes conceptualizing a holistic framework of the investigated M-health application adoption factors.
Findings
Despite the exploration of multifaceted adoption determinants and behaviors, the current publications exhibit limitations. The studies not only show a lack of representation of multiple health behaviors and medical conditions but also fail to involve data from low- and middle-developing countries, where M-health application utilization is crucial. Findings revealed that there is a considerable absence of a solid theoretical foundation that unveils a gap in interpreting the adoption factors effectively. Understanding cultural and demographic variances and exploring financial factors and healthcare provider involvement is essential for tailoring M-health application interventions. Continuous assessment of technological factors and evaluation of the actual impact of M-health application usage on behavioral changes and health outcomes will further enhance the effectiveness and adoption of these technologies.
Originality/value
This review is one of the first comprehensive reviews of determinants of M-health application adoption targeting health behavior change for the general public and patients.
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Shikha Agnihotri, Rekha Mewafarosh and Shivani Malhan
Purpose: The prominence of quality education for building sustainable development is undeniable and is distinctly pointed out in 1 of the 14 sustainable development goals (SDGs)…
Abstract
Purpose: The prominence of quality education for building sustainable development is undeniable and is distinctly pointed out in 1 of the 14 sustainable development goals (SDGs). In the same context, this study intends to investigate the role of university commitment, perceived organisational prestige, student satisfaction, and perceived employability in enhancing sustainability in higher education.
Need of the Study: To evaluate how student satisfaction mediates the relationship between university commitment, perceived organisational prestige, and perceived employability with sustainable university institutes.
Methodology: An adapted questionnaire was used in this study to capture the perception of 458 management graduates selected through the purposive sampling method. Partial least squares structural equation modelling (PLS-SEM) technique was used to analyse the data with the help of Smart PLS software.
Findings: The results of this study show that student satisfaction is the strongest predictor of sustainable university institutes. University commitment was found to lead to student satisfaction significantly. Furthermore, student satisfaction wasn’t found to play the role of mediator in the proposed model.
Practical Implications: This study aims to fulfil theoretical, research, and management implications for students, higher education institutes (HEIs), and policymakers. HEIs are recommended to instil university commitment, perceived organisational prestige and student satisfaction via various practices and amendments in their curriculum. Students are recommended to enhance their perceived employability to achieve career sustainability.
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J.G. Lee, F. Guo, K.N. Subramanian and J.P. Lucas
The influence of the thermal reflow profile on the formation and resultant morphology of the intermetallic layer that developed at the Ni particle reinforcements within an…
Abstract
The influence of the thermal reflow profile on the formation and resultant morphology of the intermetallic layer that developed at the Ni particle reinforcements within an eutectic Sn‐Ag composite solder matrix was investigated. The composite solder was fabricated by mechanically dispersing 15 vol% Ni particles into eutectic Sn‐3.5Ag solder paste. Two distinct intermetallic compound (IMC) morphological microstructures were observed around the Ni reinforcements. IMC morphological microstructure apparently varied depending on the amount of heat input and differences in heating rates used in the reflow profile. A “sunflower” IMC morphology was typically noted when the total amount of heat input was small. However, with sufficient heat input, a faceted “blocky” IMC morphology was consistently achieved. Multiple‐reflow thermal profiling experiments were conducted to measure and compare the amount of heat input necessary to change the sunflower IMC morphology around Ni particle reinforcements to the blocky morphology.
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Yongqiang Sun, Yafei Feng, Xiao-Liang Shen and Xitong Guo
Prior researches on the adoption of mobile health services (MHS) concentrate on the subjective cognitive appraisals resulting in technology adoption, while ignoring how to shape…
Abstract
Purpose
Prior researches on the adoption of mobile health services (MHS) concentrate on the subjective cognitive appraisals resulting in technology adoption, while ignoring how to shape those cognitive appraisals by the objective message design strategies which are easier to operate in practice. Based on protection motivation theory (PMT), the current research aims to explore the antecedents of cognitive appraisals by focusing on message design strategies of fear appeal and coping appeal.
Design/methodology/approach
A two-stage scenario-based survey of 204 participants was conducted to collect data. The authors chose SPSS and covariance-based structural equation modeling (CB-SEM) approach with the software LISREL 8.8 to test our model.
Findings
The results show that the relationship between fear appeal and fear arousal is inverted U-shaped such that the degree of fear arousal is the greatest when the fear appeal is at a moderate level. Perceived usefulness for the message with negative framing is higher than that with positive framing. Furthermore, fear appeal and coping appeal have a significant interaction on the adoption of MHS at different stages.
Research limitations/implications
The sample data of this study come from a special health service of a special group in China, which limits the universality of our research results for other groups or health care services. Therefore, future researchers can validate the model in other research scenarios and sample populations.
Originality/value
This study shows how fear appeal and coping appeal work together to influence individuals' adoption intention. The authors’ findings expand the theoretical depth of PMT and fear theory, enriching the theoretical connotation of framing effect in mobile health technology adoption context, which add new insights to design more persuasive messages through fear appeal and coping appeal for researchers and MHS providers in mobile health communication or propaganda.