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Article
Publication date: 31 August 2020

Tingting Wang, Shimin Dai, Hailong Liao and Haihong Zhu

To fabricate high performance parts, this paper aims to systematically study the pores characteristics and their formation mechanisms in selective laser melting (SLM) AlSi10Mg.

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Abstract

Purpose

To fabricate high performance parts, this paper aims to systematically study the pores characteristics and their formation mechanisms in selective laser melting (SLM) AlSi10Mg.

Design/methodology/approach

Cubes of 10 × 10 × 5 mm were manufactured in different laser power, scan speed and scan space. Optical microscope (OM) and scanning electron microscopes (SEM) were used to observe morphology of pores.

Findings

Round or irregular pores were found in SLMed AlSi10Mg parts. All the round pores have smooth inner walls and locate in the melt pool. The formation mechanisms of the round pores are contributed to the evaporation of elements in the melt pool, H2O, high laser energy input and hollow powder. Irregular pores have rough inner walls. Big scan space, unevenness of the upper surface, large layer thickness, spatter and oxide are the main reasons of generating irregular pores which outside the melt pool. Instability of keyhole leads to the irregular pores locate in the bottom of keyhole mode melt pool.

Originality/value

Relationship between pores and melt pool were studied systematically for the first time. Researches of pores characteristics and their formation mechanisms in SLMed AlSi10Mg would be a valuable reference for researchers to obtain an important insight into and control the defect in SLMed Al alloy.

Details

Rapid Prototyping Journal, vol. 26 no. 9
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 November 2021

Shimin Dai, Hailong Liao, Haihong Zhu and Xiaoyan Zeng

For the laser powder bed fusion (L-PBF) technology, the side surface quality is essentially important for industrial applicated parts, such as the inner flow parts. Contour is…

208

Abstract

Purpose

For the laser powder bed fusion (L-PBF) technology, the side surface quality is essentially important for industrial applicated parts, such as the inner flow parts. Contour is generally adopted at the parts’ outline to enhance the side surface quality. However, the side surface roughness (Ra) is still larger than 10 microns even with contour in previous studies. The purpose of this paper is to study the influence of contour process parameters, laser power and scanning velocity on the side surface quality of the AlSi10Mg sample.

Design/methodology/approach

Using L-PBF technology to manufacture AlSi10Mg samples under different contour process parameters, use a laser confocal microscope to capture the surface information of the samples, and obtain the surface roughness Ra and the maximum surface height Rz of each sample after analysis and processing.

Findings

The results show that the side surface roughness decreases with the increase of the laser power at the fixed scanning velocity of 1,000 mm/s, the side surface roughness Ra stays within the error range as the contour velocity increases. It is found that the Ra increases with the scanning velocity increasing and the greater the laser power with the greater Ra increases when the laser power of contour process parameters is 300 W, 350 W and 400 W. The Rz maintain growth with the contour scanning velocity increasing at constant laser power. The continuous uniform contour covers the pores in the molten pool of the sample edge and thus increase the density of the sample. Two mechanisms named “Active adhesion” and “Passive adhesion” cause sticky powder.

Originality/value

Formation of a uniform and even contour track is key to obtain the good side surface quality. The side surface quality is determined by the uniformity and stability of the contour track when the layer thickness is fixed. These research results can provide helpful guidance to improve the surface quality of L-PBF manufactured parts.

Details

Rapid Prototyping Journal, vol. 28 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 11 May 2020

Kwun-fu Chan

This study aims to examine the problems encountered during the establishment of the Central Police Academy (CPA) under the Nationalist regime from 1936 to 1949. While the…

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Abstract

Purpose

This study aims to examine the problems encountered during the establishment of the Central Police Academy (CPA) under the Nationalist regime from 1936 to 1949. While the authoritarian party-state unified the police academies by forceful means, this catalyzed the cleavage between the schools of police studies and resulted in power struggles over police education, intellectual thought, collectivity and even the national reform of police administration. More than narrating the progress of power consolidation, this study attempts to identify the problems underlying the factional strife and to reveal the interwoven pattern of these power struggles, exploring the confusion regarding what the police is, a question that troubled Chinese policemen from the mainland to Taiwan.

Design/methodology/approach

This paper explains the emergence of the factional strife from the beginning of the preliminary growth of the Police Academies in Nanking and Chekiang. It widely makes use of the official archives from Japan Center for Asian Historical Records and Historica Academia to show the dynamic situation in police education and administration. Rather, the official publications of the Police Academies and their affiliated associations reveal the hidden political agenda behind a unified framework as the party-state claimed. Moreover, official gazettes, memorials and newspapers are also used to strengthen the core argument of this study.

Findings

This paper examines the impact of the factional strife between the police leaders Dai Li and Li Shizhen on the CPA from 1936 to 1949. It illustrates that the establishment of the CPA ostensibly unified the nationwide police force but triggered power struggles over the control of the police administration. More importantly, it also shows how the factions strove for larger shares of power under the supreme doctrines that Chiang Kai-shek and the party-state imposed.

Originality/value

The failure of police education to become powerful was a special case among other more typical institutions. The governors coercively merged the police academies and created robust conditions for growth under the shelter of state authority. The police force did not follow the same path of national monopoly as what recent studies found but drifted apart with its vested interests and incompatible beliefs. Hence, the greater the demand for centralized control by the state, the greater the tension of the factional strife.

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Publication date: 17 October 2015

Masayuki Murayama and Lloyd Burton

Myth is a story of archetypical personas who behave in ways and with motives that we recognize in ourselves. We use myth as a way of reminding ourselves of the relationship…

Abstract

Myth is a story of archetypical personas who behave in ways and with motives that we recognize in ourselves. We use myth as a way of reminding ourselves of the relationship between motives, actions, and consequences. Myths can serve either as inspirational or cautionary tales, and sometimes as both. But “myth” can also mean a fabricated story intended to create a false impression, and to achieve storytellers’ ends when they have decided the truth will not suffice. We apply the myth of Cassandra to the millennium-long recorded history of giant tsunamis in Japan. After each of these catastrophes, survivors sought to warn future generations of their recurrences. But, each time, their progeny eventually lost the memory of these lessons, and lost their lives when the next monster wave overwhelmed them. Only when they kept the lessons as living knowledge in everyday life, could they manage to escape from monster tsunamis. In this chapter, we use the myth of Cassandra in conjunction with the myth of Prometheus, the bringer of fire to humankind, as a metaphor for Japan’s growing reliance on nuclear power. Government and utility companies built powerful but inherently dangerous cauldrons in the nation’s disaster-prone landscapes, assuring the public they could control the fire’s fury and defend it against nature’s. As images of atomic bomb victims were still vivid and widely shared in Japan, they had to overcome the public fear of radioactivity by fabricating a “myth of safety.” The nuclear disaster made the public distrust the government and utility companies, which lingers in the process of reconstruction from the disaster. Myths can either reveal hidden truths or mask hidden lies. The Japanese people must now learn to distinguish one from the other.

Details

Special Issue Cassandra’s Curse: The Law and Foreseeable Future Disasters
Type: Book
ISBN: 978-1-78560-299-3

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Article
Publication date: 14 December 2023

Peng Xiao, Haiyan Zhang, Shimin Yin and Zhe Xia

This study aims to explore the role of international ambidexterity (IA) in improving the innovation capability of emerging market multinationals. In particular, the main purpose…

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Abstract

Purpose

This study aims to explore the role of international ambidexterity (IA) in improving the innovation capability of emerging market multinationals. In particular, the main purpose of this research is to study the relationship amongst digitalisation, IA and innovation performance (IP) amongst multinational enterprises in China’s healthcare industry.

Design/methodology/approach

The data for this investigation were collected from 134 listed companies in China’s healthcare industry during the study period. This study tested the hypotheses by constructing a two-way fixed-effects model.

Findings

The results show that both the balance dimension and the combined dimension of IA have significant positive effects on IP. Digitalisation not only has a direct positive effect on IP but also positively moderates the positive correlation between IA and IP.

Originality/value

Previous studies have not captured the relationship between ambidexterity, digitalisation and IP, and this study helps to fill in the gap and examine these associations in China’s healthcare industry. The results of this study provide valuable insights for healthcare industry managers to understand the role of ambidexterity and digitalisation in innovation in the context of internationalisation.

Details

European Journal of Innovation Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1460-1060

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Article
Publication date: 7 July 2020

Maria J. Grant, Robyn R. Lotto and Ian D. Jones

The study aims to construct an understanding of professional academic writing network structures to inform organisational strategic investment in academic staff development.

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Abstract

Purpose

The study aims to construct an understanding of professional academic writing network structures to inform organisational strategic investment in academic staff development.

Design/methodology/approach

Longitudinal social network analysis is used to examine the personal-networks evident in the publication portfolios of a purposive sample of four international academics across each quartile of the SCOPUS defined area of General Nursing's top 100 authors.

Findings

Trends in the publication portfolios of elite academics across gender, sector and geographic location are presented. In the first years of successful writing for publication, authors collaborate within a single highly connected co-author network. This network will typically expand to include new co-authors, before additional separate co-author collaborations emerge (three- to four- years). Authors experience steady growth in co-author numbers four- to seven- years from first co-authored publication. After a period of rapid expansion, these collaborations coalesce into a smaller number of highly connected groups (eight- to ten- years). Most collaborations occur within the higher education sector and across multiple disciplines including medicine, social sciences and psychology. Male co-authors are disproportionately represented in what is a predominantly female profession.

Practical implications

The development of extended co-author networks, locally, internationally and across the higher education sector, enable authors to attain the marker of achievement required by universities and government funding bodies, namely sustained output of academic publications. Identified trends support the inclusion of investment in academic time and resources in higher education institutions strategic and operational plans to enable academic staff to develop interdisciplinary professional networks. In focussing this investment on gender equality, female academics will experience parity of opportunity in achieving their organisational and personal goals relating to professional academic writing. Medium-term investment may be required before the impact of that investment becomes apparent.

Originality/value

This is the first example of social network analysis used to determine characteristics of professional academic writing portfolios over time. Findings inform the type and range of investment required to facilitate academic staff writing activities, specifically those publishing in the area of General Nursing.

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