Junbo Liu, Yaping Huang, Shengchun Wang, Xinxin Zhao, Qi Zou and Xingyuan Zhang
This research aims to improve the performance of rail fastener defect inspection method for multi railways, to effectively ensure the safety of railway operation.
Abstract
Purpose
This research aims to improve the performance of rail fastener defect inspection method for multi railways, to effectively ensure the safety of railway operation.
Design/methodology/approach
Firstly, a fastener region location method based on online learning strategy was proposed, which can locate fastener regions according to the prior knowledge of track image and template matching method. Online learning strategy is used to update the template library dynamically, so that the method not only can locate fastener regions in the track images of multi railways, but also can automatically collect and annotate fastener samples. Secondly, a fastener defect recognition method based on deep convolutional neural network was proposed. The structure of recognition network was designed according to the smaller size and the relatively single content of the fastener region. The data augmentation method based on the sample random sorting strategy is adopted to reduce the impact of the imbalance of sample size on recognition performance.
Findings
Test verification of the proposed method is conducted based on the rail fastener datasets of multi railways. Specifically, fastener location module has achieved an average detection rate of 99.36%, and fastener defect recognition module has achieved an average precision of 96.82%.
Originality/value
The proposed method can accurately locate fastener regions and identify fastener defect in the track images of different railways, which has high reliability and strong adaptability to multi railways.
Details
Keywords
Haoyu Gao, Ruixiang Jiang, Wei Liu, Junbo Wang and Chunchi Wu
This chapter investigates the effect of the geographical distance between institutional investors and firms on managers' financial misconduct. The evidence shows that the…
Abstract
This chapter investigates the effect of the geographical distance between institutional investors and firms on managers' financial misconduct. The evidence shows that the likelihood of committing financial misconduct by management is positively associated with distance. The distance effect is more prominent for firms with higher information asymmetry and more dedicated institutional investors. In line with the balance between risk-taking and benefit extraction from misconduct, the severity of financial misconduct is higher for firms closer to their institutional investors. Results show that geographical proximity can significantly reduce the cost of information production and facilitate monitoring through access to soft information.
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Haoyu Gao, Ruixiang Jiang, Wei Liu, Junbo Wang and Chunchi Wu
Using initial public offering (IPO) involuntary delisting data, this chapter examines whether and how motivated institutional investors affect the survivability of IPO firms. The…
Abstract
Using initial public offering (IPO) involuntary delisting data, this chapter examines whether and how motivated institutional investors affect the survivability of IPO firms. The empirical evidence shows that the likelihood of future delisting is much lower for IPOs with more motivated institutional investors. This impact is more pronounced for firms with higher information asymmetry. The motivated institutional investors also facilitate better post-IPO operating performance. The results are consistent with the prediction of the limited attention theory.
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Yonghong Xia, Junbo Liu, Bo Xu and Hongjian Wu
The purpose of this paper is to propose a novel hybrid excitation permanent magnet synchronous generator (HEPMSG) utilizing tooth harmonic for excitation, the structural features…
Abstract
Purpose
The purpose of this paper is to propose a novel hybrid excitation permanent magnet synchronous generator (HEPMSG) utilizing tooth harmonic for excitation, the structural features and operation principle of which are also described.
Design/methodology/approach
To obtain the operation performance quickly, this paper derives the mathematical model of the machine system represented by circuit, and analyzes the operation mode of rectifier circuit in the tooth harmonic excitation system, then the standard state equations for each operation mode are obtained. Combining the inductance parameter of this machine with the load resistance and inductance, the armature current waveform, the field current waveform and tooth harmonic winding current waveform are obtained by using the numerical method to solve the standard state equation.
Findings
Comparing with the experimental results, the availability of the principle and the validity of the model of the machine system are verified.
Practical implications
This HEPMSG is a new brushless self-excited and self-regulated generator, which is suitable for an independent power source.
Originality/value
Unlike the existing hybrid excitation permanent magnet machine, this HEPMSG utilized the inherent tooth harmonic EMF of the rotor to adjust the air-gap magnetic field of the permanent magnet machine.
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Keywords
Shan Chen, Meiqi Fang, Linlin Wang, Jiafu Su and Junbo Tuo
This paper intends to address the decision-making and coordination of green supply chain (GSC) considering risk-averse manufacturers under mixed carbon policy.
Abstract
Purpose
This paper intends to address the decision-making and coordination of green supply chain (GSC) considering risk-averse manufacturers under mixed carbon policy.
Design/methodology/approach
This paper focuses on a GSC consisting of a manufacturer and a retailer, in which the manufacturer is risk-averse (R-A). This paper employs Stackelberg game theory and mean variance analysis to assess the pricing decision-making process under various scenarios. Furthermore, cost-sharing contracts are introduced to coordinate the GSC.
Findings
The research results suggest that the green level of the product and the profit of the GSC under a centralized scenario are higher than those under a decentralized scenario, while the retail price is lower. Under the decentralized scenario, the green level of product, wholesale price and manufacturer’s profit in the R-A scenario are lower than the values in the risk-neutrality scenario, while retailer's profit is higher. In addition, when a cost-sharing contract is utilized for coordination in the GSC, it can lead to Pareto improvement, regardless of whether the manufacturer makes risk-neutrality or R-A decisions.
Originality/value
This research provides a deeper understanding of GSC decision-making and coordination strategy under mixed carbon policy with consideration of R-A from a theoretical perspective and provides decision support for enterprises to choose strategies in practice.
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Keywords
Chaoqun Ma, Lan Liu, Junbo Wang and Jing Chen
The purpose of this paper is to examine the risk of inefficiency of China's stock index futures market by investigating the opportunity and profitability of exchange‐traded fund…
Abstract
Purpose
The purpose of this paper is to examine the risk of inefficiency of China's stock index futures market by investigating the opportunity and profitability of exchange‐traded fund (ETF) arbitrage. The explanation of behavioral risk to market efficiency is examined.
Design/methodology/approach
Based on cost‐of‐carry model, some assumptions about market efficiency were examined, and statistical tests were implemented to support the findings.
Findings
In China, borrowing and lending interest rates are quite different; dividends are small and paid in an irregular manner; and short sale cannot be used in arbitrage by all investors. It is found that the Chinese index futures market is far from efficient.
Originality/value
With reference to the empirical study, this is believed to be the first application of behavioral study to the study of market efficiency. The analysis of the statistics about Chinese index futures market and the algorithm parameters are very valuable for in‐depth understanding of the emerging markets.
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Xueying Zhou, Wentao Sun, Zehui Zhang, Junbo Zhang, Haibo Chen and Hongmei Li
The purpose of this study is to study the quantitative evaluation method of contact wire cracks by analyzing the changing law of eddy current signal characteristics under…
Abstract
Purpose
The purpose of this study is to study the quantitative evaluation method of contact wire cracks by analyzing the changing law of eddy current signal characteristics under different cracks of contact wire of high-speed railway so as to provide a new way of thinking and method for the detection of contact wire injuries of high-speed railway.
Design/methodology/approach
Based on the principle of eddy current detection and the specification parameters of high-speed railway contact wires in China, a finite element model for eddy current testing of contact wires was established to explore the variation patterns of crack signal characteristics in numerical simulation. A crack detection system based on eddy current detection was built, and eddy current detection voltage data was obtained for cracks of different depths and widths. By analyzing the variation law of eddy current signals, characteristic parameters were obtained and a quantitative evaluation model for crack width and depth was established based on the back propagation (BP) neural network.
Findings
Numerical simulation and experimental detection of eddy current signal change rule is basically consistent, based on the law of the selected characteristics of the parameters in the BP neural network crack quantitative evaluation model also has a certain degree of effectiveness and reliability. BP neural network training results show that the classification accuracy for different widths and depths of the classification is 100 and 85.71%, respectively, and can be effectively realized on the high-speed railway contact line cracks of the quantitative evaluation classification.
Originality/value
This study establishes a new type of high-speed railway contact wire crack detection and identification method, which provides a new technical means for high-speed railway contact wire injury detection. The study of eddy current characteristic law and quantitative evaluation model for different cracks in contact line has important academic value and practical significance, and it has certain guiding significance for the detection technology of contact line in high-speed railway.
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Rui Zhang, Qiang Zhang, Junbo Cheng and Xiaodong Zhou
Achieving accurate trajectory tracking control of robot manipulators is challenging due to dynamic model errors and uncertain payloads. This paper aims to enhance trajectory…
Abstract
Purpose
Achieving accurate trajectory tracking control of robot manipulators is challenging due to dynamic model errors and uncertain payloads. This paper aims to enhance trajectory tracking performance for robots with n degrees of freedom (DOF).
Design/methodology/approach
This study proposes a robust motion control framework that combines uncertainty and disturbance estimator with model-based compensation. The proposed framework ensures precise trajectory tracking in robot manipulators. In addition, uncertainties in the high-DOF robot dynamics are estimated through a simple model-based compensation for system error dynamics. The stability of the closed-loop system of the proposed framework is analyzed and proved.
Findings
The results indicate that the proposed framework can significantly reduce tracking errors and increase disturbance resistance. The simulation results of a two-link robotic arm verify the effectiveness of the proposed method. The results of the experiments conducted on a seven-DOF torque-controlled Flexiv4S manipulator demonstrate the superior trajectory tracking performance and robustness of the proposed algorithm.
Originality/value
This study introduces a highly efficient, robust motion control framework for high-DOF robots, which can improve the trajectory tracking performance in the presence of model uncertainties.
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This paper intends to provide a thematic literature review of the scholarly research articles orbiting the Sino–African education cooperation and exchange, published between 2005…
Abstract
Purpose
This paper intends to provide a thematic literature review of the scholarly research articles orbiting the Sino–African education cooperation and exchange, published between 2005 and 2022.
Design/methodology/approach
The methodology used in this paper is qualitative in nature with a thematic approach. The author used content analysis techniques to spotlight the major themes of the topic studied. The author selected the papers and theses, based on their heuristic capacity, from two major databases for the English and Chinese literature: Web of Science and CNKI. The selection process resulted in 60 high-quality peer-reviewed articles and theses. Another 30 research articles and theses were used as supplementary resources.
Findings
The literature concentrates on six points: the historical development, the nature of the exchange, the frameworks of the cooperation, vocational training and knowledge transfer, African students in China and their experiences, and education cooperation and soft power. However, research tends to be somewhat polemical rather than an academic debate between Chinese researchers and their western peers. Therefore, empirical studies beyond the geopolitical preoccupations and the “YEA” or “NAY” to the Sino–African education exchange are critically needed.
Practical implications
The implications of this study go beyond the east/west or developed/developing world rhetoric and focus more on sustainable educational development on a global scale. Understanding how the literature on the Sino–African education engagement is shaping, provides valuable insights into international education in the global south. It can also be implied to approach educational engagement with other destinations such as India, Türkiye and Brazil.
Originality/value
This thematic literature review concentrates on the educational aspect of Sino–African relations. It compares English and Chinese peer-reviewed scholarly articles and theses on China–Africa educational engagement and has heuristic implications for sustainable educational development globally.
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Hongmei Li, Junling Shi, Xiangdong Li, Junbo Zhang and Yunlong Chen
High-speed maglev technology can address the issues of adhesion, friction, vibration and high-speed current collection in traditional wheel-rail systems, making it an important…
Abstract
Purpose
High-speed maglev technology can address the issues of adhesion, friction, vibration and high-speed current collection in traditional wheel-rail systems, making it an important direction for the future development of high-speed rail technology.
Design/methodology/approach
This paper elaborates on the demand and significance of developing high-speed maglev technology worldwide and examines the current status and technological maturity of several major high-speed maglev systems globally.
Findings
This paper summarizes the challenges in the development of high-speed maglev railways in China. Based on this analysis, it puts forward considerations for future research on high-speed maglev railways.
Originality/value
This paper describes the development status and technical maturity of several major high-speed maglev systems in the world for the first time, summarizes the existing problems in the development of China's high-speed maglev railway and on this basis, puts forward the thinking of the next research of China's high-speed maglev railway.