Fan Aihua, Wang Zhongzhi and Ding Fangqing
The purpose of this paper is to give some limit theorems on ε‐neighborhood and ε‐increasing runs of continuous‐valued dependent random sequence. In the main result no assumptions…
Abstract
Purpose
The purpose of this paper is to give some limit theorems on ε‐neighborhood and ε‐increasing runs of continuous‐valued dependent random sequence. In the main result no assumptions are made concerning the random variables. As corollary a result on independent case is obtained.
Design/methodology/approach
The crucial part of the proof is to construct a non‐negative supper‐martingale depending on a parameter by using the moment generating function, and then applying the Doob's martingale convergence theorem.
Findings
The upper and lower bounds of the deviations from the sums of arbitrary continuous‐valued random variables from the reference distributions are obtained.
Research limitations/implications
The computation of asymptotic log‐likelihood ratio h(P|Q) is the main limitations, and it is difficult to obtain the rigorous bounds of the deviations.
Practical implications
A useful method to study the property for runs of dependent random sequence.
Originality/value
The new approach of study strong limit behavior for dependent random sequence.
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Hamid Khobzi and Babak Teimourpour
The purpose of this study is to assign polarity score to each post from Facebook fan pages, and then examine whether the Comments submitted by users on a post from fan page have a…
Abstract
Purpose
The purpose of this study is to assign polarity score to each post from Facebook fan pages, and then examine whether the Comments submitted by users on a post from fan page have a significant relationship with the popularity of that post. Being aware of how to enhance the popularity of posts will help companies in terms of administrating their fan pages.
Design/methodology/approach
In the context of fan page and post popularity, the authors test significance of the relationship between Comments’ polarity and number of Likes and Comments of a post in different Facebook pages by regression method. The data are collected from different fan page posts in Facebook, and a sentiment analysis approach is proposed to accomplish this research.
Findings
Results show that the relation between users’ Comments and popularity of fan page posts is strongly significant. Outcomes of this research are useful for every company in terms of monitoring and managing their brand fan pages on social networking sites such as Facebook.
Originality/value
Investigation of factors influencing popularity of fan page posts in social media is almost a new area of study that dates back to recent years. The authors use a sentiment analysis approach to evaluate a new concept describing the relationship between users’ Comments and popularity of posts from Facebook fan pages. Moreover, a part of dataset is extracted from Facebook by a crawler which is an advantage to prior studies.
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Ning Liu, Linyu Zhou, LiPing Xu and Shuwei Xiang
As the cost of completing a transaction, the green merger and acquisition (M&A) premium paid on mergers can influence whether the acquisition creates value or not. However…
Abstract
Purpose
As the cost of completing a transaction, the green merger and acquisition (M&A) premium paid on mergers can influence whether the acquisition creates value or not. However, studies linking M&A premiums to firm value have had mixed results, even fewer studies have examined the effect of green M&A premiums on bidders’ firm value. The purpose of this paper is to investigate whether and how green M&A premiums affect firm value in the context of China’s heavy polluters.
Design/methodology/approach
Using 323 deals between 2008 and 2019 among China’s heavy polluters, this paper estimates with correlation analysis and multiple regression analysis.
Findings
Green M&A premiums are negatively associated with firm value. The results are more significant when firms adopt symbolic rather than substantive corporate social responsibility (CSR) strategies. Robustness and endogeneity tests corroborate the findings. The negative relation is stronger when acquiring firms have low governmental subsidy and environmental regulation, when firms have overconfident management, when firms are state-owned and when green M&A occurs locally or among provinces in the same region. This study also analyzes agency cost as an intermediary in the relationship between green M&A premium and firm value, which lends support to the agency-view hypothesis.
Originality/value
This study provides systemic evidence that green M&A premiums damage firm value through agency cost channel and the choice of CSR strategies from the perspective of acquirers. These findings enrich the literature on both the economic consequences of green M&A premiums and the determinants of firm value and provide a plausible explanation for mixed findings on the relationship between green M&A premiums and firm value.
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Wang Zhang, Lizhe Fan, Yanbin Guo, Weihua Liu and Chao Ding
The purpose of this study is to establish a method for accurately extracting torch and seam features. This will improve the quality of narrow gap welding. An adaptive deflection…
Abstract
Purpose
The purpose of this study is to establish a method for accurately extracting torch and seam features. This will improve the quality of narrow gap welding. An adaptive deflection correction system based on passive light vision sensors was designed using the Halcon software from MVtec Germany as a platform.
Design/methodology/approach
This paper proposes an adaptive correction system for welding guns and seams divided into image calibration and feature extraction. In the image calibration method, the field of view distortion because of the position of the camera is resolved using image calibration techniques. In the feature extraction method, clear features of the weld gun and weld seam are accurately extracted after processing using algorithms such as impact filtering, subpixel (XLD), Gaussian Laplacian and sense region for the weld gun and weld seam. The gun and weld seam centers are accurately fitted using least squares. After calculating the deviation values, the error values are monitored, and error correction is achieved by programmable logic controller (PLC) control. Finally, experimental verification and analysis of the tracking errors are carried out.
Findings
The results show that the system achieves great results in dealing with camera aberrations. Weld gun features can be effectively and accurately identified. The difference between a scratch and a weld is effectively distinguished. The system accurately detects the center features of the torch and weld and controls the correction error to within 0.3mm.
Originality/value
An adaptive correction system based on a passive light vision sensor is designed which corrects the field-of-view distortion caused by the camera’s position deviation. Differences in features between scratches and welds are distinguished, and image features are effectively extracted. The final system weld error is controlled to 0.3 mm.
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Xuhui Ye, Gongping Wu, Fei Fan, XiangYang Peng and Ke Wang
An accurate detection of overhead ground wire under open surroundings with varying illumination is the premise of reliable line grasping with the off-line arm when the inspection…
Abstract
Purpose
An accurate detection of overhead ground wire under open surroundings with varying illumination is the premise of reliable line grasping with the off-line arm when the inspection robot cross obstacle automatically. This paper aims to propose an improved approach which is called adaptive homomorphic filter and supervised learning (AHSL) for overhead ground wire detection.
Design/methodology/approach
First, to decrease the influence of the varying illumination caused by the open work environment of the inspection robot, the adaptive homomorphic filter is introduced to compensation the changing illumination. Second, to represent ground wire more effectively and to extract more powerful and discriminative information for building a binary classifier, the global and local features fusion method followed by supervised learning method support vector machine is proposed.
Findings
Experiment results on two self-built testing data sets A and B which contain relative older ground wires and relative newer ground wire and on the field ground wires show that the use of the adaptive homomorphic filter and global and local feature fusion method can improve the detection accuracy of the ground wire effectively. The result of the proposed method lays a solid foundation for inspection robot grasping the ground wire by visual servo.
Originality/value
This method AHSL has achieved 80.8 per cent detection accuracy on data set A which contains relative older ground wires and 85.3 per cent detection accuracy on data set B which contains relative newer ground wires, and the field experiment shows that the robot can detect the ground wire accurately. The performance achieved by proposed method is the state of the art under open environment with varying illumination.
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Xu Wang, Xin Feng and Kaixuan Guo
Quantitative analysis of existing literature is conducted to compare the textual features of ethics education in science and technology under the broad theme of ethics in science…
Abstract
Purpose
Quantitative analysis of existing literature is conducted to compare the textual features of ethics education in science and technology under the broad theme of ethics in science and technology. On this basis, the authors reveal the research hotspots and topic evolution in this field, and propose development suggestions in conjunction with the 5W theory.
Design/methodology/approach
In this paper, the authors visualize the graph and quantify the indicators in four aspects: time series, institutional collaboration, author co-authorship, and research hotspots.
Findings
Compared to ethics of science and technology, the research results in the field of ethics of science and technology education are limited. There is still room for improvement in the low density of cooperation between authors and institutions. The research themes are focused on theoretical discussions and countermeasure research. At present, the reform of ethics of science and technology is still in its infancy and has not yet formed a perfect system for education and personnel training. It is necessary for research on the ethical theory of technology to provide theoretical support.
Originality/value
In the context of sustainable development strategies, it is beneficial to explore the path of pedagogical optimization of ethics of science and technology in this study. This includes the maintenance of a good research environment and the realization of a healthy development in the field of science and technology.
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Michele Ciotti, Giampaolo Campana and Mattia Mele
This paper aims to present a survey concerning the accuracy of thermoplastic polymeric parts fabricated by additive manufacturing (AM). Based on the scientific literature, the aim…
Abstract
Purpose
This paper aims to present a survey concerning the accuracy of thermoplastic polymeric parts fabricated by additive manufacturing (AM). Based on the scientific literature, the aim is to provide an updated map of trends and gaps in this relevant research field. Several technologies and investigation methods are examined, thus giving an overview and analysis of the growing body of research.
Design/methodology/approach
Permutations of keywords, which concern materials, technologies and the accuracy of thermoplastic polymeric parts fabricated by AM, are used for a systematic search in peer-review databases. The selected articles are screened and ranked to identify those that are more relevant. A bibliometric analysis is performed based on investigated materials and applied technologies of published papers. Finally, each paper is categorised and discussed by considering the implemented research methods.
Findings
The interest in the accuracy of additively manufactured thermoplastics is increasing. The principal sources of inaccuracies are those shrinkages occurring during part solidification. The analysis of the research methods shows a predominance of empirical approaches. Due to the experimental context, those achievements have consequently limited applicability. Analytical and numerical models, which generally require huge computational costs when applied to complex products, are also numerous and are investigated in detail. Several articles deal with artificial intelligence tools and are gaining more and more attention.
Originality/value
The cross-technology survey on the accuracy issue highlights the common critical aspects of thermoplastics transformed by AM. An updated map of the recent research literature is achieved. The analysis shows the advantages and limitations of different research methods in this field, providing an overview of research trends and gaps.
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Jianpeng Wu, Biao Ma, Heyan Li and Chengnan Ma
The purpose of this paper is to study friction and wear properties of three types of steels against paper-based friction disc, including 65Mn, 20#steel and 30CrAl, so as to obtain…
Abstract
Purpose
The purpose of this paper is to study friction and wear properties of three types of steels against paper-based friction disc, including 65Mn, 20#steel and 30CrAl, so as to obtain the appropriate working conditions for different friction materials in the transmission system.
Design/methodology/approach
Based on actual working conditions, pin-on-disc tests are conducted on a universal material tester. The two evaluation indexes, including average friction coefficient and variation coefficient, are introduced to analyze the different friction properties among three types of steel. Furthermore, the temperature-dependent wear pattern and wear depth are subsequently studied.
Findings
The results show that 65Mn is more suitable for working under heavy load and low velocity, but 30CrAl and 20#steel are suitable for working under light load and high velocity. Moreover, wear primarily occurs on paper-based material and peaks at about 325.
Practical implications
This research of different materials and friction property for friction pairs is helpful to improve the performance and prolong the service life of transmission systems.
Originality/value
Suitable working conditions of different friction materials are obtained, and the correlation between wear and decomposition in high temperature is verified.