Guo Yi, Junhua Xu and Chuanbo Zheng
There are obvious differences in corrosion resistance of different 2205 welding joints with different ratios of austenite and ferrite, from the top to the bottom, the austenite…
Abstract
Purpose
There are obvious differences in corrosion resistance of different 2205 welding joints with different ratios of austenite and ferrite, from the top to the bottom, the austenite content decreased gradually while the ferrite increased. In each region of welded joint, the pitting resistance number of ferrite is higher than that of austenite; pitting corrosion is more likely to occur in austenite phase first on the top region of the weld and in the secondary phase precipitates on the other regions of the weld. The fluctuation of the ratio of austenite and ferrite has a great influence on performance of passive film in 3.5 per cent NaCl solution.
Design/methodology/approach
To study the corrosion behavior of welded joint, the samples were obtained by laser hybrid welding. Pitting corrosion was studied in different area of welded joint. The Mott–Schottky curves of welded joints were measured to study the passive film on the different welded joint area.
Findings
Due to the difference of heat input and the limit of filler depth of the wire, the microstructure of duplex stainless steel laser welding joint has obvious difference in the thickness direction. In addition, there will be harmful secondary phase (such as chromium nitride and σphase) precipitates in the lower part of the joint. For the welded joint, the corrosion resistance decreases with the increase in the difference of the microstructure. Pitting corrosion usually takes the two phases as the nucleation point and grows up. The surface of 2205 duplex stainless steel laser hybrid welding joint cannot form a complete passive film in 3.5 per cent NaCl solution, and the more the ratios of austenite and ferrite deviate from equilibrium position (50:50), the worse the performance of passive film is.
Originality/value
In this paper, the authors attempt to establish the correlation between the semiconductor electronic properties of passive film and the difference of microstructures and the component in a joint welded by laser hybrid welding. The effect of passive film on the corrosion resistance of the weld was further investigated.
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Xuexin Xu, Xiaodong Yang, Junhua Lu, Ji Lan, Tai-Quan Peng, Yingcai Wu and Wei Chen
Massively multiplayer online role-playing games (MMORPGs) create quasi-real social systems in which players can interact with one another, and quasi-real economic systems where…
Abstract
Purpose
Massively multiplayer online role-playing games (MMORPGs) create quasi-real social systems in which players can interact with one another, and quasi-real economic systems where players can consume and trade in-game items with virtual currency. The in-game currency price, an important indicator of a virtual economy, is highly contingent on players’ behavioral interaction in MMORPGs. The purpose of this paper is to adopt a network perspective to examine how topological characteristics of social networks in an MMORPG, namely, network externalities, density, and closure, would exert impacts on the in-game currency price.
Design/methodology/approach
Players’ behavioral data were collected from a popular MMORPG in China on a weekly basis for 52 weeks. With a time series analytical approach, the empirical model for the price function of in-game currency was estimated with vector autoregression.
Findings
The results show that the number of core avatars and network density are positively associated with in-game currency price, while network closure has a negative effect on in-game currency price. However, in-game currency price is found to have no significant relationship with the trade volume of the currency.
Originality/value
This study fills in an important research gap by investigating factors influencing the in-game currency price of MMORPGs from a network perspective, which contributes to the existing literature of network effects and advances our understanding about how players’ interaction will influence the dynamics of a virtual economy. The findings could offer useful insights for online game companies to better understand their players’ social interaction and consumption behavior.
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Xiaowei Zhu, Yanqiu Chen, Yu Liu, Yongqiang Deng, Changyu Tang, Weilian Gao, Jun Mei, Junhua Zhao, Tong Liu and Jian Yang
The purpose of this paper is to provide additive manufacturing-based solutions for preparation of elastomeric foam with broaden compressive stress plateau.
Abstract
Purpose
The purpose of this paper is to provide additive manufacturing-based solutions for preparation of elastomeric foam with broaden compressive stress plateau.
Design/methodology/approach
Mechanic models are developed for obtaining designs of foam cell units with enhanced elastic buckling. An experimental approach is taken to fabricate the foams based on direct ink writing technique. Experimental and simulation data are collected to assist understanding of our proposals and solutions.
Findings
A simple tetragonal structured elastomeric foam is proposed and fabricated by direct ink writing, in which its cell unit is theoretically designed by repeating every four filament layers. The foam exhibits a broader stress plateau, because of the pronounced elastic buckling under compressive loading as predicted by the authors’ mechanic modeling. A two-stage stress plateaus as observed in the foam, being attributed to the dual elastic buckling of the cell units along two lateral directions of the XY plane during compression.
Research limitations/implications
Future work should incorporate more microscopic parameters to tune the elastomeric foam for mechanic performance testing on linear elastic deformation and densification of polymer matrix.
Practical implications
Additive manufacturing offers an alternative to fabricate elastomeric foam with controlled cell unit design and therefore mechanics. Our results comment on its broad space for development such superior cushioning or damping material in the fields of vibration and energy absorption.
Originality/value
This work has contributed to new knowledge on preparation of high performance elastomeric foam by providing a better understanding on its cell structure, being printed using direct ink writing machines.
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Huyen Nguyen, Haihua Chen, Jiangping Chen, Kate Kargozari and Junhua Ding
This study aims to evaluate a method of building a biomedical knowledge graph (KG).
Abstract
Purpose
This study aims to evaluate a method of building a biomedical knowledge graph (KG).
Design/methodology/approach
This research first constructs a COVID-19 KG on the COVID-19 Open Research Data Set, covering information over six categories (i.e. disease, drug, gene, species, therapy and symptom). The construction used open-source tools to extract entities, relations and triples. Then, the COVID-19 KG is evaluated on three data-quality dimensions: correctness, relatedness and comprehensiveness, using a semiautomatic approach. Finally, this study assesses the application of the KG by building a question answering (Q&A) system. Five queries regarding COVID-19 genomes, symptoms, transmissions and therapeutics were submitted to the system and the results were analyzed.
Findings
With current extraction tools, the quality of the KG is moderate and difficult to improve, unless more efforts are made to improve the tools for entity extraction, relation extraction and others. This study finds that comprehensiveness and relatedness positively correlate with the data size. Furthermore, the results indicate the performances of the Q&A systems built on the larger-scale KGs are better than the smaller ones for most queries, proving the importance of relatedness and comprehensiveness to ensure the usefulness of the KG.
Originality/value
The KG construction process, data-quality-based and application-based evaluations discussed in this paper provide valuable references for KG researchers and practitioners to build high-quality domain-specific knowledge discovery systems.
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Ziming Zeng, Yu Shi, Lavinia Florentina Pieptea and Junhua Ding
Aspects extracted from the user’s historical records are widely used to define user’s fine-grained preferences for building interpretable recommendation systems. As the aspects…
Abstract
Purpose
Aspects extracted from the user’s historical records are widely used to define user’s fine-grained preferences for building interpretable recommendation systems. As the aspects were extracted from the historical records, the aspects that represent user’s negative preferences cannot be identified because of their absence from the records. However, these latent aspects are also as important as those aspects representing user’s positive preferences for building a recommendation system. This paper aims to identify the user’s positive preferences and negative preferences for building an interpretable recommendation.
Design/methodology/approach
First, high-frequency tags are selected as aspects to describe user preferences in aspect-level. Second, user positive and negative preferences are calculated according to the positive and negative preference model, and the interaction between similar aspects is adopted to address the aspect sparsity problem. Finally, an experiment is designed to evaluate the effectiveness of the model. The code and the experiment data link is: https://github.com/shiyu108/Recommendation-system
Findings
Experimental results show the proposed approach outperformed the state-of-the-art methods in widely used public data sets. These latent aspects are also as important as those aspects representing the user’s positive preferences for building a recommendation system.
Originality/value
This paper provides a new approach that identifies and uses not only users’ positive preferences but also negative preferences, which can capture user preference precisely. Besides, the proposed model provides good interpretability.
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Quan Yuan, Ning Li, Yujie Li and Junhua Hao
The purpose of this paper is to study the corrosion behavior of 316L stainless steel under cavitation condition in simulated seawater.
Abstract
Purpose
The purpose of this paper is to study the corrosion behavior of 316L stainless steel under cavitation condition in simulated seawater.
Design/methodology/approach
Electrochemical impedance spectroscopy and electrochemical noise analyses are used to characterize the electrochemical process during the cavitation erosion process.
Findings
Because of good corrosion resistance of this material, mechanical damage is the main cause of cavitation erosion. The alloy surface is in active dissolution state during the cavitation erosion process, and the corrosion rate is accelerated as time prolongs which is verified by electrochemical results.
Originality/value
Electrochemical noise is an effective way to study the corrosion under cavitation erosion process.
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Feng Cheng, Weixi Ji and Junhua Zhao
The disbonding of DLC coating is a main failure mode in the high-speed cavitation condition, which shortens the service life of the bearing. This study aims to investigate…
Abstract
Purpose
The disbonding of DLC coating is a main failure mode in the high-speed cavitation condition, which shortens the service life of the bearing. This study aims to investigate influence of adhesion strength on cavitation erosion resistance of DLC coating.
Design/methodology/approach
Three DLC coatings with different adhesion strengths were grown on the 304 steel surfaces by using a cathodic arc plasma deposition method. Cavitation tests were performed by using a vibratory test rig to investigate the influence of adhesion strength on cavitation erosion resistance of a DLC coating. The cavitation mechanism of the substrate-coating systems was further discussed by means of surface analyses.
Findings
The results indicated that, the residual stress decreased and then increased with the increasing DLC coating thickness from 1 µm to 2.9 µm, and the lower residual stress can improve the adhesion strength of the DLC coating to the substrate. It was also concluded that, the plastic deformation as well as the fracture occurred on the DLC coating surface at the same time, owing to higher residual stress and poorer adhesion strength. However, lower residual stress and better adhesion strength could help resist the occurrence of the coating fracture.
Originality/value
Cavitation tests were performed by using a vibratory test rig to investigate the influence of adhesion strength on cavitation erosion resistance of the DLC coating. The plastic deformation and the fracture occurred on the DLC coating surface at the same time, owing to higher residual stress and poorer adhesion of coating. Lower residual stress and better adhesion of coating could resist the occurrence of the DLC coating fracture.
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A.G. Mohan Das Gandhi, K. Soorya Prakash and V. Kavimani
This paper aims to examine the investigations made on the corrosion behaviour of magnesium (Mg) substrate electrodeposited using different nano-materials.
Abstract
Purpose
This paper aims to examine the investigations made on the corrosion behaviour of magnesium (Mg) substrate electrodeposited using different nano-materials.
Design/methodology/approach
This study uses nano-materials such as those of reduced graphene oxide (r-GO), titanium-di-oxide (TiO2) and also r-GO/TiO2 nano-composites (dispersed through ultra-sonication process) at 3-min time interval. Crystalline nature of synthesized TiO2 is studied through X-ray diffraction and its pore volume is measured to be approximately 0.1851ccg-1 by Brunauer Emmett Teller analysis.
Findings
Surface morphology of the developed set of specimens inspected through scanning electron microscopy and energy dispersive spectroscopy establishes a clean surface coating and further witnesses for only minimal defects. Electrochemical behaviour of the developed coating is studied exhaustively using Tafel polarization and electrochemical impedance spectroscopy in 0.1 M Na2SO4 solution.
Originality/value
Incremental corrosion resistance exhibited by developed composite coating owes to the factors viz. chemical stability and hydrophobic tendency of TiO2 and r-GO; these known engineering facts resist the flow of ions into the corrosive media and thereby reduce the rate of corrosion.
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Long Wang, Fengtao Wang, Linkai Niu, Xin Li, Zihao Wang and Shuping Yan
The purpose of this paper is to combine triboelectric nanogeneration technology with ball bearing structure to achieve energy collection and fault monitoring.
Abstract
Purpose
The purpose of this paper is to combine triboelectric nanogeneration technology with ball bearing structure to achieve energy collection and fault monitoring.
Design/methodology/approach
In this paper, according to the rotation mode of ball bearings, the freestanding mode of triboelectric nanogeneration is selected to design and manufacture a novel triboelectric nanogeneration device Rolling Ball Triboelectric Nanogenerator (RB-TENG) which combines rotary energy collection with ball bearing fault self-sensing.
Findings
The 10,000s continuous operation experiment of the RB-TENG is carried out to verify its robustness. The accurate feedback relationship between the RB-TENG and rotation velocity can be demonstrated by the fitting comparison between the theoretical and experimental electrical signal periods at a certain time. By comparing the output electrical signals of the normal RB-TENG and the rotor spalling RB-TENG and polytetrafluoroethylene (PTFE) balls with different degrees of wear at 500 r/min, it can be concluded that the RB-TENG has an ideal monitoring effect on the radial clearance distance of bearings. The spalling fault test of the RB-TENG stator inner ring and rotor outer ring is carried out.
Originality/value
Through coupling experiments of rotor spalling fault of the RB-TENG and PTFE balls fault with different degrees of wear, it can be seen that when rotor spalling fault occurs, balls wear has a greater impact on the normal operation of the RB-TENG, and it is easier to identify. The fault self-sensing ability of the RB-TENG can be obtained, which is expected to provide an effective scheme for monitoring the radial wear clearance distance of ball bearings.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2024-0295/
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Heather R. Bell and Robin Bell
This work makes a case for legitimacy as a framework with which to examine how educators made decisions about implementing entrepreneurship education (EE) in higher education…
Abstract
Purpose
This work makes a case for legitimacy as a framework with which to examine how educators made decisions about implementing entrepreneurship education (EE) in higher education institutions (HEIs) to better understand the educator within the educational ecosystem. It then uses a new legitimacy framework that includes self-legitimacy to examine the issues a group of educators in China encountered when implementing new constructivist entrepreneurship modules in their non-entrepreneurship curricula.
Design/methodology/approach
The researchers utilized focus groups to collect data from 24 groups of educators at HEIs in 4 regions of China. The researchers used a bottom-up thematic analysis process to identify themes and used legitimacy as a lens to analyze the data.
Findings
The results are presented in three main categories: theorization, or how the practice aligns with existing practice; diffusion, or how the practice is perceived by stakeholders; and self-legitimacy, or how the practice impacts the educator’s image of the self. The data show that legitimization of their constructivist EE practice has not occurred at each of these stages, leaving educators struggling to rationalize how the new practice fits into their existing ecosystem.
Originality/value
Using legitimacy as an approach, the research adds to an understanding of how and why entrepreneurship educators adopt practice and how they are empowered to change practice within their existing institutional structures. It brings different legitimacy theories into one framework to examine changes to EE practice and it applies self-legitimacy to education, an area previously only examined in high power distance situations like law enforcement, but which is appropriate for high power distance educational cultures like China.