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Existing research has shown the role of social media in facilitating general protest participation. However, there is a noticeable gap in understanding the dynamics related to…
Abstract
Purpose
Existing research has shown the role of social media in facilitating general protest participation. However, there is a noticeable gap in understanding the dynamics related to explicitly unlawful behaviors during protests, which have become increasingly prominent in recent times. Drawing upon the communication mediation model (O-S-O-R model), this study proposes a moderated mediation model to delineate specific mechanisms under which social media use influences individuals' support for unlawful behaviors in protests.
Design/methodology/approach
A survey of 1,121 Hong Kong residents was conducted in the context of the 2019 Hong Kong Anti-Extradition Law Amendment Bill Movement to test the theoretical model.
Findings
Obtaining political information on social media has a dual effect on support for unlawful behaviors in protests. On one hand, social media use increases individuals' political knowledge, which is reinforced by frequent political discussions on social media. This enhanced political knowledge tends to reduce the likelihood of supporting unlawful behaviors in protests. On the other hand, acquiring political information on social media can also generate increased anger toward politics, potentially leading to a more supportive attitude toward unlawful behaviors in protests.
Originality/value
This study contributes to the expanding field of research on digital activism by revealing the intricate mechanisms by which social media usage shapes support for unlawful behaviors in protests. It also expands our understanding of explicit unlawful behaviors within protests as a distinct form of political behavior.
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Ying Zhang, Fei Shen, Jean Carlos Paredes and Cong Wang
College students who are interested in experiencing and learning about other cultures could be potential agents to ongoing social and policy initiatives in promoting societal…
Abstract
Purpose
College students who are interested in experiencing and learning about other cultures could be potential agents to ongoing social and policy initiatives in promoting societal changes. As universities intensify their efforts toward embracing cultural diversity, it is imperative to gauge how these diversity initiatives resonate with students' developmental stage and pursuits in diverse campus climates. However, what kinds of educational experiences/contexts students choose for enhancing cultural competence, and how seeking diversity experiences might benefit college students in emotional wellbeing and cognitive skills, are under-investigated.
Design/methodology/approach
This study explores the relationships among college students' diversity-seeking behaviors, cultural competence, perspective-taking, and flourishing. A total of 359 college students from a STEM-focused university participated in this study. Students were recruited from classes over four semesters, from 2021 to 2023.
Findings
Students exhibited moderate to high levels of interest in seeking diversity in their learning experiences. Results from the structural equation modeling showed that higher levels of diversity-seeking in learning were associated with higher levels of perceived cultural competence, as well as higher levels of perspective-taking and flourishing.
Originality/value
This research delves into experiential and extracurricular dimensions of learning diversity, bridging a significant gap in academic literature. This study also elucidates the links between aspects of diversity engagement, cultural competence, and positive outcomes for college students, which underscores the significance of diversity-focused educational opportunities in higher education. Such opportunities are instrumental in enhancing cultural proficiency and further implications on cognitive growth and emotional well-being.
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Zujian Shen, Fei Geng, Xinxin Fan, Zhichen Shen and Haiyan Wang
This paper aims to investigate and prepare the composite polyurea greases with excellent thermal stability and tribological properties.
Abstract
Purpose
This paper aims to investigate and prepare the composite polyurea greases with excellent thermal stability and tribological properties.
Design/methodology/approach
In this paper, composite Ba-based (Ba, barium) tetra-polyurea lubricating greases were prepared with two different methods: mixing Ba-based gelatinizer and tetra-polyurea gelatinizer by a physical method; and introducing barium carboxylate into tetra-polyurea molecules by a chemical method. The properties of the products, such as heat stability, water resistance and friction performance, were analyzed with thermogravimetry, water-resistance test and four-ball friction test.
Findings
The results indicated that the products obtained by chemically introducing barium carboxylate into tetra-urea molecules showed better elevated temperature tribological properties, and the disadvantages of the polyurea greases with high temperature hardening were also obviously improved. The cone penetration rate at 180°C for 24 h is only 3 per cent. The friction coefficient can be decreased to 0.44 and the last non-seizure load value was increased from 560 N to 1,120 N without any other additives.
Originality/value
The research is significant because the prepared composite grease showed excellent performances, such as the outstanding thermal stability, water resistance and excellent extreme pressure and anti-wear properties, which may be widely applied in steel, metallurgy, bearings and other industrial fields.
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Wei‐Zhong Fei, Jian‐Xin Shen, Can‐Fei Wang and Patrick Chi‐Kwong Luk
The purpose of this paper is to propose a new outer‐rotor permanent‐magnet flux‐switching machine (ORPMFSM) for electric vehicle (EV) in‐wheel propulsion. The paper documents both…
Abstract
Purpose
The purpose of this paper is to propose a new outer‐rotor permanent‐magnet flux‐switching machine (ORPMFSM) for electric vehicle (EV) in‐wheel propulsion. The paper documents both the design procedure and performance investigation of this novel machine.
Design/methodology/approach
The topology and preliminary sizing equations of the ORPMFSM are introduced. The rotor poles are optimized, whilst the machine losses are particularly investigated, using 2‐D finite element analysis (FEA).
Findings
An ORPMFSM, with 12 stator poles and 22 rotor poles, is most suitable for the proposed EV application. The analytical sizing equations are quite efficient with a sufficient accuracy for the preliminary design. The optimal rotor pole width from the FEA results is nearly 1.3 times the original value which was proposed in early literatures. The efficiency of the proposed machine under rated load is slightly low, as a result of significant eddy current losses in the permanent magnets. The losses can be effectively suppressed with the technique of magnet segmenting. The predicted outstanding performance implies that by adopting magnet segmentation the proposed machine is a leading contender for EV direct drives.
Originality/value
The outer‐rotor structure of PMFSM was not addressed in early literatures. This paper provides designers with the technical background and an alternative candidate for the EV propulsion.
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Jian‐Xin Shen, He Hao, Meng‐Jia Jin and Wei‐Zhong Fei
The purpose is to present a sensorless control method by which high‐resolution rotor position information is estimated and used for phase‐advancing operation of a high‐speed…
Abstract
Purpose
The purpose is to present a sensorless control method by which high‐resolution rotor position information is estimated and used for phase‐advancing operation of a high‐speed permanent magnet (PM) brushless DC (BLDC) motor.
Design/methodology/approach
The proposed sensorless control approach uses hardware to observe the flux vector which is excited by rotor magnets. It can provide the rotor position which is the same as the phase angle of the observed flux vector.
Findings
High‐resolution rotor position signal of the BLDC motor for dynamic phase‐advancing control cannot be directly obtained from the conventional Hall‐effect sensors, or via the traditional back‐EMF‐based sensorless control strategies in which the back‐EMF may be even undetectable at high‐speed. The proposed rotor‐flux‐observer (RFO)‐based sensorless control method overcomes these problems, and meanwhile provides high‐resolution rotor position information for the phase‐advancing purpose.
Originality/value
The RFO‐based sensorless control is traditionally applied to PM brushless ac (BLAC) operations, where the motor voltage vector can be calculated from the inverter switching status. However, this is not readily applicable to a BLDC motor since the voltage of the floating phase cannot be calculated. Moreover, during high‐speed operation, the microprocessor may not be sufficiently fast to calculate the high‐resolution rotor position. Therefore, in this paper, it is proposed to use hardware to observe the rotor‐flux‐vector. The microprocessor only samples the vector's α‐ and β‐components and calculates the phase angle, hence, its burden is low. The proposed method is validated with a 1.8 kW 85,000 rpm BLDC motor system.
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Hu Ming‐li, Shen Fei‐fei and Chen Ya‐huan
The purpose of this paper is to propose a multi‐attribute decision‐making method based on the concept of extended dominance relation and variable precision rough sets.
Abstract
Purpose
The purpose of this paper is to propose a multi‐attribute decision‐making method based on the concept of extended dominance relation and variable precision rough sets.
Design/methodology/approach
First, the definitions of extended dominance relation and variable precision rough sets are introduced in detail. Second, two types of extended dominance rules are obtained from the pairwise comparison table. Third, a scoring function is defined and sorted to score all the objects. Finally, a case about the emergency decision making after an earthquake is discussed to demonstrate the feasibility and efficiency of the method.
Findings
It is found that the new method can deal with decision‐making problems with incomplete information. Numerical examples show that the method has good application prospects in public emergency decision making, including an earthquake emergency.
Practical implications
The method shown in the paper can be used for solving decision‐making problems with incomplete information.
Originality/value
The paper develops a novel multi‐attribute decision analysis method dealing with incomplete information based on rough sets theory.
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– The paper purposes a novel SFPM machine topology with radial and circumferential permanent magnets (PMs). The paper aims to discuss this issue.
Abstract
Purpose
The paper purposes a novel SFPM machine topology with radial and circumferential permanent magnets (PMs). The paper aims to discuss this issue.
Design/methodology/approach
In order to reduce the flux leakage in the stator-outer region and consequently achieve higher magnetic material utilization in switched flux permanent magnet (SFPM) machine, a novel topology with radial and circumferential PMs is proposed. This topology (SFRCPM) has the same structure as conventional SFPM (CSFPM) machine except of the additional set of radially magnetized PMs located around the back iron and surrounded by a laminated ring frame. Using finite element analysis (FEA) the influence of the design parameters on the performance is investigated in order to obtain an effective optimization procedure. Internal and external rotor SFRCPM machines with either NdFeB or ferrite magnets are investigated, optimized and compared with the CSFPM machine having the same size, copper loss and stator/rotor pole combination.
Findings
It is concluded that comparing SFRCPM with its CSFPM machine counterpart, internal rotor SFRCPM machine can achieve high PM flux-linkage per magnet volume, however reduced slot area leads to low output torque, whereas external rotor SFRCPM machine can produce higher torque and torque per magnet volume.
Originality/value
This paper proposes a novel SFPM machine topology.
Details
Keywords
I.A.A. Afinowi, Z.Q. Zhu, Y. Guan, Jean-Claude Mipo and P. Farah
– The purpose of this paper is to comparatively study the conventional, i.e. single magnet, and novel hybrid-magnet switched-flux permanent-magnet (HMSFPM) machines.
Abstract
Purpose
The purpose of this paper is to comparatively study the conventional, i.e. single magnet, and novel hybrid-magnet switched-flux permanent-magnet (HMSFPM) machines.
Design/methodology/approach
The HMSFPM machines utilize two magnet types, i.e. low-cost ferrites and NdFeB. Thus, a set of magnet ratios (?), defined as the quotient of the NdFeB volume to the total PM volume, is introduced. This allows any desired performance and cost trade-off to be designed. Series- and parallel-excited magnet configurations are investigated using 2-dimensional finite element analysis.
Findings
The torque of the HMSFPM machines is lower than the NdFeB SFPM machine but the flux-weakening performance is improved for similar machine efficiency. If the machine dimensions are unconstrained, the HMSFPM machines can have the same torque for reduced material costs and a moderate increase in machine dimensions. Ferrite SFPM machines have the lowest cost for the same torque but a significant increase in machine dimensions is required. Finally, the series-excited HMSFPM machine is the preferred over the parallel-excited HMSFPM machine because it has superior demagnetization withstand capability.
Research limitations/implications
Mechanical and winding eddy current losses are not considered in the efficiency map calculations.
Originality/value
The NdFeB SFPM, ferrite SFPM, series-excited HMSFPM, and the parallel-excited HMSFPM machines are compared for their electromagnetic performance, flux-weakening, PM demagnetization, efficiency, and material costs.
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The purpose of this paper is to investigate and compare the influence of end-effect on the torque-speed characteristics of three conventional switched flux permanent magnet (SFPM…
Abstract
Purpose
The purpose of this paper is to investigate and compare the influence of end-effect on the torque-speed characteristics of three conventional switched flux permanent magnet (SFPM) machines having different stator/rotor pole combinations, i.e. 12/10, 12/13 and 12/14 as well as three novel topologies with less permanent magnets (PMs), i.e. multi-tooth, E-core and C-core.
Design/methodology/approach
SFPM machines combine the advantages of simple and robust rotor and easy management of the temperature due to the location of the PMs and armature windings on the stator. However, due to spoke location of the PMs a large flux leakage in the end region, i.e. end-effect, can be observed which could result in a large reduction in the electromagnetic performance. Therefore, the influence of end-effect on the torque-speed characteristics is investigated. 3D-finite element analyses (FEA) results are compared with their 2D-FEA counterparts in order to account for the end-effect influence.
Findings
It has been concluded that due to end flux leakage, lower torque capability in the constant torque region is observed in the six machines. However, improved flux-weakening capability in the conventional machines can be exhibited at high current levels, whereas due to the large inductance lower power capability in the multi-tooth, E-core and C-core machines is obtained.
Research limitations/implications
The influence of temperature rise on the performance is not included.
Originality/value
This paper has analysed the influence of end-effect on the torque-speed characteristics of several SFPM machines.
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Pengbin Gao, Yexin Liu, Xiaoli Li and Yan Wang
This paper aims to unravel the technological innovation pattern in China’s aerospace industry. The technological innovation pattern of China’s aerospace industry is identified and…
Abstract
Purpose
This paper aims to unravel the technological innovation pattern in China’s aerospace industry. The technological innovation pattern of China’s aerospace industry is identified and its theoretical foundation, structure, philosophy, formation and effects on the development of China’s aerospace industry are explored.
Design/methodology/approach
First, the theoretical foundation of synergy innovation of China’s aerospace industry is reviewed to further identify the technological innovation pattern. Second, Chinese ancient philosophy (dialectical thinking) is used to explain the structure and process of synergy innovation in China’s aerospace industry. Third, the formation process of synergy innovation is introduced, and, finally, the effects of synergy innovation are discussed.
Findings
The technological innovation pattern of China’s aerospace industry has undergone an evolutionary process. During this process, China’s aerospace firms have formed a unique technological innovation pattern, synergy innovation, under China’s special political and economic background. The synergy innovation has three characteristics, including original, integrated and application-based. The synergy innovation pattern application is one of the most important reasons behind the great achievements of China’s aerospace industry.
Originality/value
A unique technological innovation pattern, synergy innovation, is proposed for the first time. A new perspective for understanding innovation is provided by applying the Chinese dialectical thinking to decipher the philosophy of the technological innovation pattern. Based on this, this paper suggests that China’s aerospace industry should follow the situation and apply the synergy innovation pattern to achieve development and growth. This paper also illustrates a multi-method approach and emphasizes the different levels of organizing for innovation.
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