Hong Xiao, Yugang Duan, Zhongbo Zhang and Ming Li
This paper aims to investigate an approach for mental fatigue detection and estimation of assembly operators in the manual assembly process of complex products, with the purpose…
Abstract
Purpose
This paper aims to investigate an approach for mental fatigue detection and estimation of assembly operators in the manual assembly process of complex products, with the purpose of founding the basis for adaptive transfer and demonstration of assembly process information (API), and eventually making the manual assembly process smarter and more human-friendly.
Design/methodology/approach
The proposed approach detects and estimates the mental state of assembly operators by electroencephalography (EEG) signal recording and analysis in an engine assembly experiment. When the subjects perform assembly tasks, their EEG signal is recorded by a portable EEG recording system called Emotiv EPOC+ headset. The feature set of the EEG signal is then extracted by calculating its power spectrum density (PSD), followed by data dimension reduction based on principal component analysis (PCA). The dimension-reduced data are classified by using support vector machines (SVMs), and hence, the mental state of assembly operators can be estimated during the assembly process.
Findings
The experimental result shows that the proposed approach is able to estimate the mental state of assembly operators within an acceptable accuracy range, and the PCA-based dimension reduction method performs very well by representing the high-dimensional EEG feature set with just a few principal components.
Originality/value
This paper provides theoretical and experimental basis for the API transfer and demonstration based on human cognition. It provides a new idea to seek balance between the improvement of production efficiency and the sustainable utilization of human resources.
Details
Keywords
The purpose of this paper is to examine the relationship between team heterogeneity and team performance in entrepreneurial team and is also of significance in guiding the…
Abstract
Purpose
The purpose of this paper is to examine the relationship between team heterogeneity and team performance in entrepreneurial team and is also of significance in guiding the management practice of an entrepreneurial team.
Design/methodology/approach
The study is carried out based on an experiment, in which a 2×2 experimental group is devised to collect data concerned with the heterogeneity of entrepreneurial team’s expertise and the attitude toward heterogeneity.
Findings
The entrepreneurial team’s heterogeneity has a significant effect on entrepreneurial performance; the entrepreneurial team’s heterogeneity influences entrepreneurial performance through team task conflict; attitudes toward heterogeneity play a mediating role in the above process.
Originality/value
This paper is carried out based on an experiment which can be used to determine the mediating effects of team conflict on the relationship between team expertise heterogeneity and the entrepreneurial performance.
Details
Keywords
Ce Rong, Zhongbo He, Guangming Xue, Guoping Liu, Bowen Dai and Zhaoqi Zhou
Owing to the excellent performance, giant magnetostrictive materials (GMMs) are widely used in many engineering fields. The dynamic Jiles–Atherton (J-A) model, derived from…
Abstract
Purpose
Owing to the excellent performance, giant magnetostrictive materials (GMMs) are widely used in many engineering fields. The dynamic Jiles–Atherton (J-A) model, derived from physical mechanism, is often used to describe the hysteresis characteristics of GMM. However, this model, despite cited by many different literature studies, seems not to possess unique expressions, which may cause great trouble to the subsequent application. This paper aims to provide the rational expressions of the dynamic J-A model and propose a numerical computation scheme to obtain the model results with high accuracy and fast speed.
Design/methodology/approach
This paper analyzes different published papers and provides a reasonable form of the dynamic J-A model based on functional properties and physical explanations. Then, a numerical computation scheme, combining the Newton method and the explicit Adams method, is designed to solve the modified model. In addition, the error source and transmission path of the numerical solution are investigated, and the influence of model parameters on the calculation error is explored. Finally, some attempts are made to study the influence of numerical scheme parameters on the accuracy and time of the computation process. Subsequently, an optimization procedure is proposed.
Findings
A rational form of the dynamic J-A model is concluded in this paper. Using the proposed numerical calculation scheme, the maximum calculation error, while computing the modified model, can remain below 2 A/m under different model parameter combinations, and the computation time is always less than 0.5 s. After optimization, the calculation speed can be enhanced with the computation accuracy guaranteed.
Originality/value
To the best of the authors’ knowledge, this paper is the first one trying to provide a rational form of the dynamic J-A model among different citations. No other research studies focus on designing a detailed computation scheme targeting the fast and accurate calculation of this model as well. And the performance of the proposed calculation method is validated in different conditions.
Details
Keywords
Nasiru Salihu, Poom Kumam, Sulaiman Mohammed Ibrahim and Huzaifa Aliyu Babando
Previous RMIL versions of the conjugate gradient method proposed in literature exhibit sufficient descent with Wolfe line search conditions, yet their global convergence depends…
Abstract
Purpose
Previous RMIL versions of the conjugate gradient method proposed in literature exhibit sufficient descent with Wolfe line search conditions, yet their global convergence depends on certain restrictions. To alleviate these assumptions, a hybrid conjugate gradient method is proposed based on the conjugacy condition.
Design/methodology/approach
The conjugate gradient (CG) method strategically alternates between RMIL and KMD CG methods by using a convex combination of the two schemes, mitigating their respective weaknesses. The theoretical analysis of the hybrid method, conducted without line search consideration, demonstrates its sufficient descent property. This theoretical understanding of sufficient descent enables the removal of restrictions previously imposed on versions of the RMIL CG method for global convergence result.
Findings
Numerical experiments conducted using a hybrid strategy that combines the RMIL and KMD CG methods demonstrate superior performance compared to each method used individually and even outperform some recent versions of the RMIL method. Furthermore, when applied to solve an image reconstruction model, the method exhibits reliable results.
Originality/value
The strategy used to demonstrate the sufficient descent property and convergence result of RMIL CG without line search consideration through hybrid techniques has not been previously explored in literature. Additionally, the two CG schemes involved in the combination exhibit similar sufficient descent structures based on the assumption regarding the norm of the search direction.
Details
Keywords
Ye Wang, Fusheng Wang and Shiyu Liu
This paper aims to discuss whether the attention of investors to abnormalities can serve as a mechanism for the influence of online media coverage on earnings management.
Abstract
Purpose
This paper aims to discuss whether the attention of investors to abnormalities can serve as a mechanism for the influence of online media coverage on earnings management.
Design/methodology/approach
Based on Baidu index data of China’s A-share listed companies between 2014 and 2018, this paper studies influencing mechanism of online media reports on earnings management from the perspective on abnormal investor attention.
Findings
The results show that internet media reports can impose pressure on managers of companies by inducing abnormal focus of the public on listed companies and further force the latter to generate more actions on the management of earnings. It is the abnormal rather than normal investor attention that mediates network media reports and earnings management.
Practical implications
This research enriches and refines the theory on influencing mechanism of media effects on earnings management and provides significant empirical evidence for future researches. Meanwhile, the conclusion of the research is of great practical importance for instructing listed firms dealing with media reports, guiding rational investment of investors and intensifying precision regulation of regulators.
Originality/value
By categorizing abnormal investor attention into active spontaneous abnormal attention which is not guided by media report and passive guided abnormal attention which is guided by media reports, the authors clarify the difference between the two categories. The result indicates that it is only the latter that is the influential mechanism of media report on earnings management.
Details
Keywords
The purpose of this paper is to forecast the future trend of Ghana’s total energy consumption (GTEC) using two grey models, which are GM(1,1) and the grey Verhulst model.
Abstract
Purpose
The purpose of this paper is to forecast the future trend of Ghana’s total energy consumption (GTEC) using two grey models, which are GM(1,1) and the grey Verhulst model.
Design/methodology/approach
The paper employs the use of Even model GM(1,1) and the grey Verhulst model to forecast GTEC for the next five years. Since various models were used, the margin for error is minimal, hence resulting in a better choice for forecasting the future. The forecast reveals that the GTEC for the next five years will increase rapidly.
Findings
The results reveal that the models can be used accurately to predict the total energy consumption smoothly. This will aid the government of Ghana to take necessary measures such as transforming the economic development pattern and enhancing the energy utilization efficiency since future patterns of energy consumed can be predicted.
Research limitations/implications
This research is meaningful to the government and all stakeholders in Ghana to help develop and appreciate the energy sector and its economic impact. This research is going to help government put in measures for efficient utilization of energy since results reveal an increase in energy consumption.
Practical implications
Research results could be used for development of the energy sector through managerial and economic decision making.
Originality/value
Ghana is a developing country and has great prospects in terms of boosting or resourcing its energy sector to meet future demands. The successfully explored models could aid the government of Ghana to formulate policies in the energy sector and generate future consumption plans.
Details
Keywords
Qiang Cao, Jianfeng Li and Mingjie Dong
The purpose of this paper is to evaluate three categories of four-degrees of freedom (4-DOFs) upper limb rehabilitation exoskeleton mechanisms from the perspective of relative…
Abstract
Purpose
The purpose of this paper is to evaluate three categories of four-degrees of freedom (4-DOFs) upper limb rehabilitation exoskeleton mechanisms from the perspective of relative movement offsets between the upper limb and the exoskeleton, so as to provide reference for the selection of exoskeleton mechanism configurations.
Design/methodology/approach
According to the configuration synthesis and optimum principles of 4-DOFs upper limb exoskeleton mechanisms, three categories of exoskeletons compatible with upper limb were proposed. From the perspective of human exoskeleton closed chain, through reasonable decomposition and kinematic characteristics analysis of passive connective joints, the kinematic equations of three categories exoskeletons were established and inverse position solution method were addressed. Subsequently, three indexes, which can represent the relative movement offsets of human–exoskeleton were defined.
Findings
Based on the presented position solution and evaluation indexes, the joint displacements and relative movement offsets of the three exoskeletons during eating movement were compared, on which the kinematic characteristics were investigated. The results indicated that the second category of exoskeleton was more suitable for upper limb rehabilitation than the other two categories.
Originality/value
This paper has a certain reference value for the selection of the 4-DOFs upper extremity rehabilitation exoskeleton mechanism configurations. The selected exoskeleton can ensure the safety and comfort of stroke patients with upper limb dyskinesia during rehabilitation training.