Jeh-Nan Pan, Chung-I Li and Jun-Wei Hsu
The purpose of this paper is to provide a new approach for detecting the small sustained process shifts in multistage systems with correlated multiple quality characteristics.
Abstract
Purpose
The purpose of this paper is to provide a new approach for detecting the small sustained process shifts in multistage systems with correlated multiple quality characteristics.
Design/methodology/approach
The authors propose a new multivariate linear regression model for a multistage manufacturing system with multivariate quality characteristics in which both the auto-correlated process outputs and the correlations occurring between neighboring stages are considered. Then, the multistage multivariate residual control charts are constructed to monitor the overall process quality of multistage systems with multiple quality characteristics. Moreover, an overall run length concept is adopted to evaluate the performances of the authors’ proposed control charts.
Findings
In the numerical example with cascade data, the authors show that the detecting abilities of the proposed multistage residual MEWMA and MCUSUM control charts outperform those of Phase II MEWMA and MCUSUM control charts. It further demonstrates the usefulness of the authors’ proposed control charts in the Phase II monitoring.
Practical implications
The research results of this paper can be applied to any multistage manufacturing or service system with multivariate quality characteristics. This new approach provides quality practitioners a better decision making tool for detecting the small sustained process shifts in multistage systems.
Originality/value
Once the multistage multivariate residual control charts are constructed, one can employ them in monitoring and controlling the process quality of multistage systems with multiple characteristics. This approach can lead to the direction of continuous improvement for any product or service within a company.
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Liang Du, Wei-Jun Zhang and Jian-Jun Yuan
This paper aims to present the design and experimental tests of an active circulating cooling system for the Experimental Advanced Superconducting Tokamak in-vessel inspection…
Abstract
Purpose
This paper aims to present the design and experimental tests of an active circulating cooling system for the Experimental Advanced Superconducting Tokamak in-vessel inspection manipulator, which will help the current manipulator prototype to achieve a full-scale in-vessel high temperature environment compatibility.
Design/methodology/approach
The high-temperature effects and heat transfer conditions of the manipulator under in-vessel environment were analyzed. An active circulating cooling system was designed and implemented on the manipulator prototype. A simulative in-vessel inspection task in a high temperature environment of 100°C was carried out to evaluate the performance of the active circulating cooling system.
Findings
The proposed active circulating cooling system was proved effective in helping the manipulator prototype to achieve its basic in-vessel inspection capability in a high temperature environment. The active circulating cooling system performance can be further improved considering the cooling structure coefficient differences in different manipulator parts.
Originality/value
For the first time, the active circulating cooling system was implemented and tested on a full-scale of the in-vessel inspection manipulator. The experimental data of the temperature distribution inside the manipulator and the operating status of the circulating system were helpful to evaluate the current active circulating cooling system design and provided effective guidance for improving the overall system performance.
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Suzhu Yu, Aloysius Tan, Wei Ming Tan, Xinying Deng, Cher Lin Tan and Jun Wei
This paper aims to develop flame-retardant (FR) polyamide 12 (PA12) nanocomposite from regenerated powder via selective laser sintering (SLS), an additive manufacturing technique.
Abstract
Purpose
This paper aims to develop flame-retardant (FR) polyamide 12 (PA12) nanocomposite from regenerated powder via selective laser sintering (SLS), an additive manufacturing technique.
Design/methodology/approach
First, the morphology, processibility, thermal and mechanical properties of PA12 regenerated powder, consisting of 50 wt% new and 50 wt% recycled powder, as well as corresponding printed specimens, were evaluated to characterize the effects of previous SLS processing. Second, flame-retardant PA12 was developed by incorporating both single and binary halogen-free flame retardants into the regenerated powder.
Findings
It was found that the printed specimens from regenerated powder had much higher tensile and impact properties compared to specimens made from new powder, which is attributed to better particulate fusion and coalescence realized in higher temperature SLS printing. The effect of FRs on thermal, mechanical and flame retardant properties of the PA12 composites/nanocomposites was investigated systematically. It was found that the nanoclay, as a synergist, improved both flame-retardant and mechanical properties of PA12. UL94 standard rating of V-0 was achieved for the printed nanocomposite by incorporating 1 wt% nanoclay into 15 wt% phosphinates FR. Moreover, on average, the tensile and impact strength of the nanocomposite were increased by 26.13% and 17.09%, respectively, in XY, YZ and Z printing orientations as compared to the equivalent flame retardant composite with 20 wt% of the phosphinates FR.
Originality/value
This paper fulfills the need to develop flame retardant parts via SLS technology with waste feedstock. It also addresses the challenge of developing flame retardant materials without obviously compromising the mechanical properties by making use of the synergistic effect of nanoclay and organic phosphinates.
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Wei Jun Wang, Rafiu King Raji, Jian Lin Han and Yuan Chen
With the current developments within the sphere of Internet of Things (IoT) technology, many conventional articles are all being fitted with smart functionalities, ranging from…
Abstract
Purpose
With the current developments within the sphere of Internet of Things (IoT) technology, many conventional articles are all being fitted with smart functionalities, ranging from chairs, beds, shoes and caps to underwear. Bags which are utility as well as fashion items have not been left out of this smart craze, albeit to a less popular degree. The purpose of this study is to fill the research gap on the subject of smart bags research and applications and to contribute to the general discourse on IoT.
Design/methodology/approach
This study adopts literature search and database review, concept mapping as well as synthesis methodologies. Relevant literature form databases such as Web of Science, Google Scholar and Bing Scholar were interrogated. Manual sifting was done to eliminate papers that do not fit the set inclusion criteria. Literature on smart bags was organized into structured frameworks using concept mapping methodology. Applying a synthesis methodology enabled an exploration of the different technological trends in smart bag research and their areas of application.
Findings
The study identified about 15 different smart bag applications and functionalities. Discussed in this study is a classification of bags based on a number of points such as way of carrying, size, utility and fabrication materials. Also discussed are the description of what constitute a smart bag, relevant technologies for smart bag design and engineering and subsequently the current trends in smart bag applications. This study also discovered that the air travel industry tend to have some difficulties with this smart bag technologies, specifically with their built-in batteries.
Practical implications
The results of this study will provide researchers and other stakeholders with key information about existing problems and opportunities in smart bag research and applications. This will go a long way to help in guiding future research as well as policymaking in smart bag design and application.
Originality/value
To the best of the authors’ knowledge, this is the first review on the subject of smart bags even though smart bag research and commercial product design continue to gain momentum in recent years.
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Guoqing Chen and Jun Wei
The extant literature on self-verification striving has primarily focused on employee recruitment and positive organizational outcomes, but there is insufficient research on its…
Abstract
Purpose
The extant literature on self-verification striving has primarily focused on employee recruitment and positive organizational outcomes, but there is insufficient research on its influence mechanism and boundary conditions. With taking charge as the mediating variable and authentic leadership as the moderating variable, this study aims to explore the relationship between self-verification striving and creative performance.
Design/methodology/approach
The authors collected 358 questionnaires from China. Linear regression was used to explore the influence mechanism and boundary conditions. Groups were classified by latent profile analysis, and differences among different groups were compared.
Findings
First, self-verification striving was significantly positively correlated with creative performance, and taking charge played a significant mediating role between them. Second, authentic leadership significantly positively moderated the relationship between self-verification striving and taking charge. Third, based on the willingness and action of self-verification striving, it was found that the taking charge and creative performance of the double high group was significantly higher than the high-medium group, while the double low group was significantly lower than the high-medium group.
Originality/value
First, this study makes up for the lack of influencing mechanism and inconsistency of research results between self-verification striving and employee outcomes. Second, the moderating effect of authentic leadership was proposed and verified, which enriched the universality of self-verification theory in Chinese context. Third, we found the differences in behaviors and outcomes among different groups, verified the uniqueness of self-verification striving in the Chinese context. It helps to explore the deep relationships that cannot be revealed by variables alone.
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Liang Du, Jia-Bo Feng, Hua Wang and Wei-jun Zhang
This paper aims to present the design and a prototype experiment of a robotic joint module for tokamak in-vessel manipulator-related research; the results will promote the…
Abstract
Purpose
This paper aims to present the design and a prototype experiment of a robotic joint module for tokamak in-vessel manipulator-related research; the results will promote the adaptation of current in-vessel inspection manipulator to achieve full tokamak in-vessel environment compatibility.
Design/methodology/approach
A flexible metallic bellow-enclosed working chamber is used to protect the main servo drive components, the active cooling method for high temperature protection and the servo control structure simplification for high radiation endurance. A joint module prototype is manufactured and tested under a similar in-vessel environmental condition for extreme condition protection validation and basic servo control ability evaluation.
Findings
The joint module prototype successfully survived the similar in-vessel environment tests and proved good mobility via closed-loop servo control. A conceptual design of a serial linkage manipulator with joint module structure is proposed for future in-vessel inspection manipulator development.
Originality/value
The proposed joint module uses common industrial servo components to achieve its full extreme in-vessel environment compatibility. Different from traditional metallic bellow application in a vacuum environment to produce a linear movement result, the proposed joint module aims to achieve rotating movement directly from the metallic bellow structure, thereby reducing the joint structure space requirement, simplifying the vacuum environment movement transmission structure and increasing the vacuum environment compatibility degree.
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Hengky Eng, Saeed Maleksaeedi, Suzhu Yu, Yu Ying Clarrisa Choong, Florencia Edith Wiria, Ruihua Eugene Kheng, Jun Wei, Pei-Chen Su and Huijun Phoebe Tham
Polymeric parts produced by 3D stereolithography (SL) process have poorer mechanical properties as compared to their counterparts fabricated via conventional methods, such as…
Abstract
Purpose
Polymeric parts produced by 3D stereolithography (SL) process have poorer mechanical properties as compared to their counterparts fabricated via conventional methods, such as injection or compression molding. Adding nanofillers in the photopolymer resin for SL could help improve mechanical properties. This study aims to achieve enhancement in mechanical properties of parts fabricated by SL, for functional applications, by using well-dispersed nanofillers in the photopolymers, together with suitable post-processing.
Design/methodology/approach
Carbon nanotubes (CNTs) have high strength and Young’s modulus, making them attractive nanofillers. However, dispersion of CNTs in photopolymer is a critical challenge, as they tend to agglomerate easily. Achieving good dispersion is crucial to improve the mechanical properties; thus, suitable dispersion mechanisms and processes are examined. Solvent exchange process was found to improve the dispersion of multiwalled carbon nanotubes in the photopolymer. The UV-absorbing nature of CNTs was also discovered to affect the curing properties. With suitable post processing, coupled with thermal curing, the mechanical properties of SL parts made from CNTs-filled resin improved significantly.
Findings
With the addition of 0.25 wt.% CNTs into the photopolymer, tensile stress and elongation of the 3D printed parts increased by 70 and 46 per cent, respectively. With the significant improvement, the achieved tensile strength is comparable to parts manufactured by conventional methods.
Practical implications
This allows functional parts to be manufactured using SL.
Originality/value
In this paper, an improved procedure to incorporate CNTs into the photopolymer was developed. Furthermore, because of strong UV-absorption nature of CNTs, curing properties of photopolymer and SL parts with and without CNT fillers were studied. Optimized curing parameters were determined and additional post-processing step for thermal curing was discovered as an essential step in order to further enhance the mechanical properties of SL composite parts.
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Ying Yang, Mai Ha Pham, Biao Yang, Jun Wei Sun and Phuong Nguyen Thu Tran
While various aspects of the vegetable supply chain (SC) have been increasingly studied, most studies tend to investigate the downstream part of the SC in terms of customer demand…
Abstract
Purpose
While various aspects of the vegetable supply chain (SC) have been increasingly studied, most studies tend to investigate the downstream part of the SC in terms of customer demand and product quality. Relatively fewer studies have focused on upstream suppliers/farmers. This study aims to understand upstream farmers’ positions in different types of vegetable SCs and identify ways of enhancing sustainable vegetable SC collaboration.
Design/methodology/approach
This study is based on an in-depth case study of a cooperative SC in Vietnam from the perspectives of both the cooperative and its farmers.
Findings
The study found that cooperative SCs are the most appropriate for Vietnamese farmers. It also identified the key activities needed to engage farmers with cooperative SCs and the mechanisms that the cooperative needs to develop. Cooperative SCs can be enhanced only when farmers are motivated to engage in SC activities and when the cooperative implements a robust management mechanism.
Originality/value
This study provides new, insightful results on how to engage with small fragmented farmers for SC collaboration and how to enhance the roles of cooperative SCs in the vegetable industry in Vietnam. It also provides information for policymakers to support sustainable vegetable SC development and maintain its sustainability.
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Srinivasan Raghavan, Mui Ling Sharon Nai, Pan Wang, Wai Jack Sin, Tao Li and Jun Wei
The paper presents a wide range of post processing heat treatment cycles performed to Electron Beam Melted (EBM) Ti6Al4V alloy and establishes correlations of heat treat process…
Abstract
Purpose
The paper presents a wide range of post processing heat treatment cycles performed to Electron Beam Melted (EBM) Ti6Al4V alloy and establishes correlations of heat treat process to microstructure and mechanical property (microhardness). The research also identifies the optimal heat treatment to obtain the best microstructure and mechanical properties (hardness and tensile).
Design/methodology/approach
Rectangular bars fabricated using EBM was used to study the different heat treatment cycles. A variety of heat treatments from sub ß-transus, super ß-transus, near ß-transus and solution aircool plus ageing were designed. After the heat treatment process, the samples were analysed for, α lath width, prior ß grain size, microhardness and nanohardness. Tensile tests were done for the heat treated samples showing most refined α lath structure with uniform globular grains.
Findings
A clear correlation was observed between α lath width and the microhardness values. The solution aircooled plus aged samples exhibited the best refinement in α-ß morphology with uniform equiaxed grains. The tensile properties of the solution aircooled plus aged samples were comparable to that of the EBM printed samples and better than ASTMF1472 specifications.
Originality/value
There is hardly any prior work related to post processing heat treatment of EBM built Ti6Al4V other than HIP treatments. The variety of heat treatment cycles and its influence in microstructure and properties, studied in this research, gives a clear understanding on how to tailor final microstructures and select the optimal heat treatment process.
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Pengpeng Sun, Hui Liu, Miao Geng, Rong Zhang, Tingting Yuan and Wei Jun Luo
The design and performance of X-band high power 3-bit phase shifter which has been fabricated in 0.25µm GaN HEMT technology are presented.
Abstract
Purpose
The design and performance of X-band high power 3-bit phase shifter which has been fabricated in 0.25µm GaN HEMT technology are presented.
Design/methodology/approach
Each bit of this phase shifter design is based on high-pass/low-pass topology.
Findings
For all eight states, the insertion loss is 12.5 ± 2.5 dB from 8-10 GHz and the input return loss is better than 9 dB over 8-10 GHz. The 3-bit phase shifter achieves a RMS phase error of 1o at 8.5 GHz and a RMS amplitude error less than 1.1dB. The measured continuous wave power data demonstrates typical input RF power handing capability of 32 dBm at 8 GHz.
Originality/value
This is to the authors’ knowledge the first published results of 3-bit AlGaN/GaN phase shifter.