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Article
Publication date: 20 September 2019

Xin-Xin Zhou, Feng Xue, Xiaofan Gou and Teng-Ming Shen

Multifilamentary Bi2Sr2CaCu2Ox (Bi2212) superconductor composite wires are the only high-temperature superconducting round wires (RW) with sufficient critical current density (Jc

100

Abstract

Purpose

Multifilamentary Bi2Sr2CaCu2Ox (Bi2212) superconductor composite wires are the only high-temperature superconducting round wires (RW) with sufficient critical current density (Jc) for superconducting magnets generating magnetic fields greater than 25 Tesla. Very complex microstructures of Bi2212 RWs including the voids or gas bubbles, filament to filament bridges and wire architecture strongly influence their electrical behavior. Especially, a large number of voids in Bi2212 superconducting filaments is believed to be the major current-limiting mechanism. However, the effect of the void structure on the Jc is not well understood yet.

Design/methodology/approach

In this paper, the authors first statistically analyzed the size and distribution of voids in filaments using the reported microscopic data, obtaining the essential statistical regularities. An electrical model was further developed to predict the Jc of multifilamentary wires while taking into account of the current limiting mechanisms of the void structure in filaments, and the current sharing roles of filament to filament bridges.

Findings

The model predicts the quantitative dependence of Jc on the number of Bi2212 filaments in each bundle of a double-restack wire and porosity. The results are useful optimizing design and fabrication of Bi2212 multifilamentary wires.

Originality/value

For the complex structure of voids and interfilamentary bridges inside Bi2212 multifilamentary superconducting wires, the authors took a statistical characterization and studied its effect on the critical current density Jc (the key index of evaluating the current carrying capacity).

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Article
Publication date: 1 March 2017

Grace Chun Guo, Crystal X. Jiang and Qin Yang

In recent decades many emerging markets (EMFs) have undertaken entrepreneurial transformations to adapt to institutional transition and industrial change. Corporate…

2851

Abstract

In recent decades many emerging markets (EMFs) have undertaken entrepreneurial transformations to adapt to institutional transition and industrial change. Corporate entrepreneurship (CE) provided EMFs viable ways to revitalize, reconfigure, and transform successfully with the dynamic environment. Although previous research examined government roles on EMFs' CE activities, little is known about the mechanisms of how government exerts influence on CE activities. To fully understand CE of EMFs, we propose a stage model to explore specific roles governments play that affect CE activities over time. In particular, we investigate how governments' grabbing hand, helping hand, and invisible hand roles affected Chinese auto firms' CE activities at different stages from 1980 to 2016. Government involvement is summarized and the advantages and disadvantages of these roles are analyzed.

Details

New England Journal of Entrepreneurship, vol. 20 no. 1
Type: Research Article
ISSN: 1550-333X

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Article
Publication date: 13 May 2024

Feng Zhou, S. S. Lu, B. Jiang and R.G. Song

This study aims to study the formation mechanism of micro-arc oxidation (MAO) coating on AZ31 magnesium alloy and how the annealing process affects its corrosion resistance.

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Abstract

Purpose

This study aims to study the formation mechanism of micro-arc oxidation (MAO) coating on AZ31 magnesium alloy and how the annealing process affects its corrosion resistance.

Design/methodology/approach

This study involved immersion experiments, electrochemical experiments and slow strain rate tensile experiments, along with scanning electron microscopy, optical microscopy observation and X-ray diffraction analysis.

Findings

The findings suggest that annealing treatment can refine the grain size of AZ31 magnesium alloy to an average of 6.9 µm at 300°C. The change in grain size leads to a change in conductivity, which affects the performance of MAO coatings. The MAO coating obtained by annealing the substrate at 300°C has smaller pores and porosity, resulting in better adhesion and wear resistance.

Originality/value

The coating acts as a barrier to prevent corrosive substances from entering the substrate. However, the smaller pores and porosity reduce the channels for the corrosive solution to pass through the coating. When the coating cracks or falls off, the corrosive medium and substrate come into direct contact. Smaller and uniform grains have better corrosion resistance.

Details

Anti-Corrosion Methods and Materials, vol. 71 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 30 July 2019

Huang-Jan Hsu, Shyh-Yuan Lee, Cho-Pei Jiang and Richard Lin

This study aims to compare the marginal fit, flexural strength and hardness for a ceramic premolar that is constructed using dental computer aided machining (CAM) and…

244

Abstract

Purpose

This study aims to compare the marginal fit, flexural strength and hardness for a ceramic premolar that is constructed using dental computer aided machining (CAM) and three-dimensional slurry printing (3DSP).

Design/methodology/approach

Dental CAM and 3DSP are used to fabricate a premolar model. To reduce the fabrication time for 3DSP, a new composition of solvent-free slurry is proposed. Before it is fabricated, the dimensions of the green body for the premolar model are enlarged to account for the shrinkage ratio. A two-stage sintering process ensures accurate final dimensions for the premolar model. The surface morphology of the green body and the sintered premolars that are produced using the two methods is then determined using scanning electronic microscopy. The sintered premolars are seated on a stone model to determine the marginal gap using an optical microscope. The hardness and the flexural strength are also measured for the purpose of comparison.

Findings

The developed solvent-free slurry for 3DSP can be used to produce a premolar green body without micro-cracks or delamination. The maximal marginal gap for the sintered premolar parts that are constructed using the green bodies from dental CAM is 98.9 µm and that from 3DSP is 72 µm. Both methods produce a highly dense zirconia premolar using the same sintering conditions. The hardness value for the dental CAM group is 1238.8 HV, which is slightly higher than that for the 3DSP group (1189.4 HV) because there is a difference in the pre-processing of the initial ceramic materials. However, the flexural strength for 3DSP is 716.76 MPa, which is less than the requirement for clinical use.

Originality/value

This study verifies that 3DSP can be used to fabricate a zirconia dental restoration device that is as good as the one that is produced using the dental CAM system and which has a marginal gap that is smaller than the threshold value. The resulting premolar restoration devices that are produced by sintering the green bodies that are produced using 3DSP and dental CAM under the same conditions have a similar hardness value, which is four times greater than that of enamel. The flexural strength of 3DSP does not meet the requirement for clinical use.

Details

Rapid Prototyping Journal, vol. 25 no. 7
Type: Research Article
ISSN: 1355-2546

Keywords

Available. Open Access. Open Access
Article
Publication date: 21 January 2022

Yong Li, Yingchun Zhang, Gongnan Xie and Bengt Ake Sunden

This paper aims to comprehensively clarify the research status of thermal transport of supercritical aviation kerosene, with particular interests in the effect of cracking on heat…

1584

Abstract

Purpose

This paper aims to comprehensively clarify the research status of thermal transport of supercritical aviation kerosene, with particular interests in the effect of cracking on heat transfer.

Design/methodology/approach

A brief review of current research on supercritical aviation kerosene is presented in views of the surrogate model of hydrocarbon fuels, chemical cracking mechanism of hydrocarbon fuels, thermo-physical properties of hydrocarbon fuels, turbulence models, flow characteristics and thermal performances, which indicates that more efforts need to be directed into these topics. Therefore, supercritical thermal transport of n-decane is then computationally investigated in the condition of thermal pyrolysis, while the ASPEN HYSYS gives the properties of n-decane and pyrolysis products. In addition, the one-step chemical cracking mechanism and SST k-ω turbulence model are applied with relatively high precision.

Findings

The existing surrogate models of aviation kerosene are limited to a specific scope of application and their thermo-physical properties deviate from the experimental data. The turbulence models used to implement numerical simulation should be studied to further improve the prediction accuracy. The thermal-induced acceleration is driven by the drastic density change, which is caused by the production of small molecules. The wall temperature of the combustion chamber can be effectively reduced by this behavior, i.e. the phenomenon of heat transfer deterioration can be attenuated or suppressed by thermal pyrolysis.

Originality/value

The issues in numerical studies of supercritical aviation kerosene are clearly revealed, and the conjugation mechanism between thermal pyrolysis and convective heat transfer is initially presented.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 32 no. 9
Type: Research Article
ISSN: 0961-5539

Keywords

Available. Open Access. Open Access
Article
Publication date: 1 August 2016

Wenqi Jiang

Different from manufacturing resources allocation problems, the prices and amounts of limited public service resources could not be changed with the consumers’ requirements and…

1677

Abstract

Purpose

Different from manufacturing resources allocation problems, the prices and amounts of limited public service resources could not be changed with the consumers’ requirements and social fairness is the most important objective for improving allocation efficiency. To measure social fairness reasonably, the purpose of this paper is fourfold: first, divide social fairness into longitudinal comparative fairness and crosswise comparative fairness, therefore providing their calculation formula and describing the comprehensive fair degree by using the interval numbers. Second, the comparison regulations of interval numbers are given and the corresponding features are also described. Third, an extension of VIKOR method is put forward for evaluating social fairness of different allocation alternatives with interval numbers. Finally, a numerical example illustrates the proposed method and clarifies the main results developed in the paper.

Design/methodology/approach

In this paper, the author depicts the social fair degree as an interval number, and thus proposes the comparison method between any two interval numbers. Based on the basis procedure of the VIKOR method, the paper proposes an extension of the fuzzy VIKOR method with the interval numbers to rank and select the compromise allocation alternatives. Finally, a numerical example illustrates the practicability of the proposed method.

Findings

The comparison of interval numbers is very important when the author evaluates the decision alternatives. Through analyzing the present comparison methods, the paper proposes the simple method of comparing the interval numbers, which can obtain the same results with the above two methods. The fuzzy VIKOR method, a popular multi-criteria decision-making method, focusses on ranking and selecting from a set of alternatives in a fuzzy environment. For the fuzzy value, the paper also proposes the extension of the VIKOR method to perform an evaluation and get the compromise alternatives.

Originality/value

According to the huge customers’ requirement, how to improve their social fair degree has become the focus in public service resources allocation, where the social fair degree may be a comprehensive concept which includes the fair degree compared with all the other allocation alternatives and the fair degree compared with the other small group under the same allocation alternative. In the paper, the author defines the above two types of fair degree and then depicts the comprehensive fair degree as their integration, which will be interval numbers.

Details

Kybernetes, vol. 45 no. 7
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 22 February 2022

Changlong Ye, Yingxin Sun, Suyang Yu, Jian Ding and Chunying Jiang

The mechanical properties between wheel and ground will affect the motion performance of wheeled omnidirectional mobile robot (OMR). MY3 wheel is an omnidirectional wheel. This…

142

Abstract

Purpose

The mechanical properties between wheel and ground will affect the motion performance of wheeled omnidirectional mobile robot (OMR). MY3 wheel is an omnidirectional wheel. This paper aims to analyze the contact mechanical characteristics between MY3 wheel and ground to improve the motion accuracy of an omnidirectional mobile platform with MY3 wheel (MY3-OMR).

Design/methodology/approach

This method takes MY3 wheel as the research objective. The normal and tangential contact mechanics model and rolling contact mechanics model of MY3 wheel are established by analyzing the structure of MY3 wheel, and thereby, the slip ratio of MY3 wheel in the process of motion is calculated. The kinematics model of MY3-OMR is optimized by taking the slip ratio as the optimization parameter that aims to improve motion accuracy of MY3-OMR.

Findings

The correctness of the mechanical analysis and the feasibility of the method are verified by the MY3-OMR prototype. Let MY3-OMR move along the set circular trajectory and square trajectory, and the error between the motion trajectory before and after optimization and the standard trajectory is obtained. It illustrates that the error in the square trajectory is reduced by 1.5%, and the circular trajectory error is reduced by 2%; therefore, the method is effective.

Originality/value

A method based on contact mechanics is proposed and verified. Through the establishment of wheel-ground contact mechanics model to optimize MY3-OMR kinematics model, and thereby, the motion accuracy of MY3-OMR is improved, which lays a foundation for MY3-OMR engineering application.

Details

Industrial Robot: the international journal of robotics research and application, vol. 49 no. 5
Type: Research Article
ISSN: 0143-991X

Keywords

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Book part
Publication date: 20 June 2017

David Shinar

Free Access. Free Access

Abstract

Details

Traffic Safety and Human Behavior
Type: Book
ISBN: 978-1-78635-222-4

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Article
Publication date: 11 January 2024

Qiang Sun, Quantong Jiang, Siwei Wu, Chang Liu, Heng Tang, L. Song, Hao Shi, Jizhou Duan and BaoRong Hou

The purpose of this paper is to explore the effect of ZnO on the structure and properties of micro-arc oxidation (MAO) coating on rare earth magnesium alloy under large…

111

Abstract

Purpose

The purpose of this paper is to explore the effect of ZnO on the structure and properties of micro-arc oxidation (MAO) coating on rare earth magnesium alloy under large concentration gradient.

Design/methodology/approach

The macroscopic and microscopic morphology, thickness, surface roughness, chemical composition and structure of the coating were characterized by different characterization methods. The corrosion resistance of the film was studied by electrochemical and scanning Kelvin probe force microscopy. The results show that the addition of ZnO can significantly improve the compactness and corrosion resistance of the MAO coating, but the high concentration of ZnO will cause microcracks, which will reduce the corrosion resistance to a certain extent.

Findings

When the concentration of zinc oxide is 8 g/L, the compactness and corrosion resistance of the coating are the best, and the thickness of the coating is positively correlated with the concentration of ZnO.

Research limitations/implications

Too high concentration of ZnO reduces the performance of MAO coating.

Practical implications

The MAO coating prepared by adding ZnO has good corrosion resistance. Combined with organic coatings, it can be applied in corrosive marine environments, such as ship parts and hulls. To a certain extent, it can reduce the economic loss caused by corrosion.

Originality/value

The effect of ZnO on the corrosion resistance of MAO coating in electrolyte solution was studied systematically, and the conclusion was new to the common knowledge.

Details

Anti-Corrosion Methods and Materials, vol. 71 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 3 December 2024

Jingqi Zhang and Shaohua Jiang

This study investigates the impact and role of digital twin technology in building automation (DTBA) from a sustainability viewpoint. It aims to enhance the understanding of how…

48

Abstract

Purpose

This study investigates the impact and role of digital twin technology in building automation (DTBA) from a sustainability viewpoint. It aims to enhance the understanding of how DTBA can boost efficiency, optimize quality and support sustainable practices in contemporary construction. By exploring the integration of DTBA with sustainable practices, the study seeks to demonstrate how DT can revolutionize building management and operations, leading to significant improvements in resource efficiency, environmental impact and overall operational excellence.

Design/methodology/approach

This research employs a bibliographic analysis and systematic review of 176 publications from the past five years (January 1, 2019 to December 31, 2023), focusing on the application and development of DTBA. The study methodically analyzes current trends, identifies research gaps and suggests future directions by synthesizing data from various studies, offering a comprehensive overview of the current state of DTBA research. The approach combines quantitative and qualitative analyses to provide robust insights into the advancements and challenges in the field.

Findings

The review identifies key development areas in DTBA, such as energy and environmental management, resource utilization within a circular economy and technology integration and interoperability. It highlights the necessity for further research to maximize DTBA’s potential in sustainable building automation. The findings suggest that while significant progress has been made, there is a critical need for innovations in data interoperability, predictive analytics and the integration of renewable energy sources to fully realize the benefits of DTBA in enhancing building sustainability.

Originality/value

This paper provides a thorough review of DTBA from a sustainability perspective, offering valuable insights into its current applications and future development potential. It serves as a crucial resource for researchers and practitioners looking to advance sustainable practices in the construction sector using DT technology. By bridging the gap between theoretical research and practical applications, the paper underscores the transformative potential of DTBA in driving sustainable development and provides a roadmap for future research and innovation in the field.

Details

Engineering, Construction and Architectural Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0969-9988

Keywords

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