Yao Chen, Ruijun Liang, Wenfeng Ran and Weifang Chen
In gearbox fault diagnosis, identifying the fault type and severity simultaneously, as well as the compound fault containing multiple faults, is necessary.
Abstract
Purpose
In gearbox fault diagnosis, identifying the fault type and severity simultaneously, as well as the compound fault containing multiple faults, is necessary.
Design/methodology/approach
To diagnose multiple faults simultaneously, this paper proposes a multichannel and multi-task convolutional neural network (MCMT-CNN) model.
Findings
Experiments were conducted on a bearing dataset containing different fault types and severities and a gearbox compound fault dataset. The experimental results show that MCMT-CNN can effectively extract features of different tasks from vibration signals, with a diagnosis accuracy of more than 97%.
Originality/value
Vibration signals at different positions and in different directions are taken as the MC inputs to ensure the integrity of the fault features. Fault labels are established to retain and distinguish the unique features of different tasks. In MCMT-CNN, multiple task branches can connect and share all neurons in the hidden layer, thus enabling multiple tasks to share information.
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Peng Sun, Weifang Chen, Yusu Shen and Dan Wang
As an important part of the rotor system, the damping coefficient of ball bearing has a great influence on the dynamic characteristics of the system. This study aims to propose a…
Abstract
Purpose
As an important part of the rotor system, the damping coefficient of ball bearing has a great influence on the dynamic characteristics of the system. This study aims to propose a theoretical calculation method and an experimental test method to obtain the damping coefficient of ball bearing.
Design/methodology/approach
Based on Hertzian contact theory and elastohydrodynamic lubrication theory, the point contact oil film damping analysis model of ball bearing is established. The comprehensive damping calculation method considering external radial load, centrifugal force, ball spin, rotational speed and lubricating oil film is derived. The multigrid method is used to obtain the oil film pressure and thickness distribution in the contact zone. The variation trend of comprehensive damping with bearing radial load, rotational speed, oil film thickness and viscosity is analyzed. The test platform is designed and the influencing factors of damping are tested.
Findings
The validity of the model and reliability of the test device are verified by comparing the good consistency obtained in the work. The results show that the comprehensive damping of ball bearing increases with the increase of radial load and decreases with the increase of rotational speed.
Originality/value
At present, the existing bearing damping model can achieve approximate calculation of damping, but the factors considered in these models are not comprehensive enough. Besides, few studies exist regarding test platform of bearing damping, and a perfect test plan has not yet been formed. In this paper, the comprehensive damping calculation model of ball bearing is improved, and a complete experimental scheme is proposed to provide reference for the comprehensive damping theory and experimental research of bearing.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0342/
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De-xing Zheng, Weifang Chen and Miaomiao Li
Thermal performances are key factors impacting the operation of angular contact ball bearings. Heat generation and transfer about angular contact ball bearings, however, have not…
Abstract
Purpose
Thermal performances are key factors impacting the operation of angular contact ball bearings. Heat generation and transfer about angular contact ball bearings, however, have not been addressed thoroughly. So far, most researchers only considered the convection effect between bearing housings and air, whereas the cooling/lubrication operation parameters and configuration effect were not taken into account when analyzing the thermal behaviors of bearings. This paper aims to analyze the structural constraints of high-speed spindle, structural features of bearing, heat conduction and convection to study the heat generation and transfer of high-speed angular contact ball bearings.
Design/methodology/approach
Based on the generalized Ohm’s law, the thermal grid model of angular contact ball bearing of high-speed spindle was first established. Next Gauss–Seidel method was used to solve the equations group by Matlab, and the nodes temperature was calculated. Finally, the bearing temperature rise was tested, and the comparative analysis was made with the simulation results.
Findings
The results indicate that the simulation results of bearing temperature rise for the proposed model are in better agreement with the test values. So, the thermal grid model established is verified.
Originality/value
This paper shows an improved model on forecasting temperature rise of high-speed angular contact ball bearings. In modeling, the cooling/lubrication operation parameters and structural constraints are integrated. As a result, the bearing temperature variation can be forecasted more accurately, which may be beneficial to improve bearing operating accuracy and bearing service life.
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Liyan Zhang and Darshini Mahadevia
Grassroots innovations (GRIs) can contribute greatly to inclusive development and reach out populations and areas not reached by or ignored by the formal sector. The purpose of…
Abstract
Purpose
Grassroots innovations (GRIs) can contribute greatly to inclusive development and reach out populations and areas not reached by or ignored by the formal sector. The purpose of the paper is to study how China's science and technology (S&T) policies and programs are translated into GRIs.
Design/methodology/approach
A case study of the grassroots organizations of farmer Chen Guangxing, of Baodi County, Tianjin City, is applied.
Findings
Government S&T policies and programs do transfer to the grassroots innovators; the government support is continuous and all-round; the grassroots innovators' leadership is important to get the support; the research and diffusion projects that grassroots innovators received are integrated in some cases; and the S&T training contributes to farmers' research and project application.
Practical implications
There is a need to increase financial support to the grassroots innovators, provide guidance to them and set up a GRI reporting mechanism.
Originality/value
The paper gives an insight into the synergies and illustrates how and why the grassroots innovators benefit from the laws, policies and ensuing programs that are not directly meant for them.
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Ren Hong, Du Yongjie, Cai Weiguang, Ma Xianrui, Wang Peng, Qin Beibei and Chen Mingman
With high-speed urbanization and strict requirements on energy conservation and environmental protection, eco-city has become the priority of urban development in China…
Abstract
With high-speed urbanization and strict requirements on energy conservation and environmental protection, eco-city has become the priority of urban development in China. Governments of all levels promote various eco-city planning schemes within a short term, but most schemes are characterized by randomness and subjectivity. To solve the lack of scientific pre-implementation evaluation for eco-city planning and improve eco-city construction quality, a systematic analysis is conducted in this study from three dimensions, namely, eco-city planning scheme, operating mechanism, and guarantee measures. A 3D evaluation model for eco-city planning is constructed through index selection. Schemes are ranked comprehensively with the distance measure method, and projection analysis is performed with the four-grid evaluation screen. Finally, the 3D evaluation model is applied to evaluate eco-city planning for Shenzhen, Chongqing, and Weifang. Results show that the model can be used to evaluate eco-city planning schemes effectively and comprehensively and offers targeted optimization suggestions in accordance with the evaluation results. Construction of the 3D evaluation model of eco-city planning based on the distance measure to determine the reasonability of eco-city planning reduces the institutional and social costs of eco-city planning practices.
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Chen Lin, Xiaohu Zhou and De'en Hou
The process of fostering and enhancing employee creativity (EC) is multifaceted and involves various challenges and contradictions, with paradoxical leadership (PL) playing a…
Abstract
Purpose
The process of fostering and enhancing employee creativity (EC) is multifaceted and involves various challenges and contradictions, with paradoxical leadership (PL) playing a crucial role. However, previous research has neglected the importance of employee emotions, resulting in an incomplete understanding of the underlying mechanisms. To address this gap, this study draws upon the triadic reciprocal determinism of social cognitive theory to construct a moderated mediation model. The objective is to investigate the mediating role of harmonious work passion (HP) in the relationship between PL and EC. Furthermore, the study aims to explore the moderating effect of proactive personality (PP).
Design/methodology/approach
Two surveys were carried out in eight enterprises situated in China. A total of 337 employees took part in the questionnaire survey to explore the correlation between PL, PP and HP. Additionally, 42 supervisors participated in evaluating the creativity of their subordinates. To test the proposed hypotheses, this study utilized hierarchical regression analysis on a sample of supervisor-subordinate pairs.
Findings
Paradoxical leadership is positively correlated with employee harmonious work passion. Harmonious work passion is positively correlated with employee creativity. Harmonious work passion plays a mediating role between paradoxical leadership and employee creativity. Proactive personality moderates the relationship between paradoxical leadership and harmonious work passion. Proactive personality moderates the indirect effect of harmonious work passion on the relationship between paradoxical leadership and employee creativity.
Practical implications
The results of this study provide practical suggestions for improving EC. For example, organizations can select supervisors who exhibit PL qualities and enhance the training programs for leaders in the domain of paradoxical thinking. Furthermore, it is crucial for leaders to prioritize the development of employees' HP and to be attentive to the distinct individual variations present within their workforce.
Originality/value
This study enriches the research on the mediating and moderating mechanism between PL and EC and opens the black box from the perspective of emotion. Moreover, this research examines the boundary condition under which PL functions. The study reveals the interaction of environment, personality, cognition and emotion on creativity and provides a new perspective and empirical support for future research.
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Jianmei Zhao and Peter J. Barry
– The purpose of this paper is to evaluate the effects of access to formal credit on rural household technical efficiency in China.
Abstract
Purpose
The purpose of this paper is to evaluate the effects of access to formal credit on rural household technical efficiency in China.
Design/methodology/approach
Based on the rural household survey data in Weifang city, Shandong province in northern China, the authors apply recent developed bootstrapped DEA approach to investigate rural technical efficiency at the household level under the consideration of off-farm activities. Rural households are then identified as credit constrained and classified as supply-side and demand-side credit constraints by applying direct elicitation method. Finally, the authors apply a tobit regression to examine the effects of credit constraints on household technical efficiency.
Findings
Rural households in China not only suffer supply-side credit constraints, but also demand-side credit constraints resulted from the transaction costs and risk rationing. The tobit regression discloses that demand-side credit constraints impose significant negative impacts on household technical efficiency.
Originality/value
The authors clarify the definition of credit constraints and classify the credit constraints into supply-side and demand-side credit constraints. The results of this paper have significant policy implications for rural finance policies in China.
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Feiqiong Chen, Wenjing Wang and Jieru Zhu
Post-merger integration (PMI) is driven by coevolving processes. This paper examines the coevolution of dynamic integration strategy and network reconstruction and explores how…
Abstract
Purpose
Post-merger integration (PMI) is driven by coevolving processes. This paper examines the coevolution of dynamic integration strategy and network reconstruction and explores how these processes systematically enable emerging market acquirers to upgrade innovation capabilities.
Design/methodology/approach
This paper conducts a multi-case study based on four Chinese overseas acquisitions of manufacturing firms. The data were collected from interviews and archival documentation.
Findings
This study develops a coevolutionary framework of dynamic integration strategy and network reconstruction to explain processes and mechanisms of an acquirer’s innovation capability upgrading. This framework identifies three network motivations, namely, network access, network connection and network synergy. Under different network motivations, dynamic transitions of the acquirer’s integration strategy coevolve with multi-level reconstruction of its networks. Collectively, they are important mechanisms driving innovation capability moves from imitation innovation to asportation and reimitation innovation and then to independent innovation.
Originality/value
This paper responds to a recent call for more insights into the dynamics of PMI and contributes to the research on emerging market multinational corporations’ post-acquisition integration. By integrating the M&A and networks literature, the paper provides evidence of unexplored mechanism of network changes during PMI. It reveals that how acquirers manage the dynamics of PMI to gradually achieve multi-level reconstruction of their networks. Based on a coevolutionary framework, the paper provides a process perspective on how the coevolution of PMI and network reconstruction promotes the upgrading of innovation capabilities.
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Yanruoyue Li, Guicui Fu, Bo Wan, Zhaoxi Wu, Xiaojun Yan and Weifang Zhang
The purpose of this study is to investigate the effect of electrical and thermal stresses on the void formation of the Sn3.0Ag0.5Cu (SAC305) lead-free ball grid array (BGA) solder…
Abstract
Purpose
The purpose of this study is to investigate the effect of electrical and thermal stresses on the void formation of the Sn3.0Ag0.5Cu (SAC305) lead-free ball grid array (BGA) solder joints and to propose a modified mean-time-to-failure (MTTF) equation when joints are subjected to coupling stress.
Design/methodology/approach
The samples of the BGA package were subjected to a migration test at different currents and temperatures. Voltage variation was recorded for analysis. Scanning electron microscope and electron back-scattered diffraction were applied to achieve the micromorphological observations. Additionally, the experimental and simulation results were combined to fit the modified model parameters.
Findings
Voids appeared at the corner of the cathode. The resistance of the daisy chain increased. Two stages of resistance variation were confirmed. The crystal lattice orientation rotated and became consistent and ordered. Electrical and thermal stresses had an impact on the void formation. As the current density and temperature increased, the void increased. The lifetime of the solder joint decreased as the electrical and thermal stresses increased. A modified MTTF model was proposed and its parameters were confirmed by theoretical derivation and test data fitting.
Originality/value
This study focuses on the effects of coupling stress on the void formation of the SAC305 BGA solder joint. The microstructure and macroscopic performance were studied to identify the effects of different stresses with the use of a variety of analytical methods. The modified MTTF model was constructed for application to SAC305 BGA solder joints. It was found suitable for larger current densities and larger influences of Joule heating and for the welding ball structure with current crowding.
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Abstract
Purpose
The paper aims to reduce the low-frequency resonance and residual vibration of the robot during the operation, improve the working accuracy and efficiency. A reduced weight and large load-to-weight ratio can improve the practical application of a collaborative robot. However, flexibility caused by the reduced weight and large load-to-weight ratio leads to low-frequency resonance and residual vibration during the operation of the robot, which reduces the working accuracy and efficiency. The vibrations of the collaborative robot are suppressed using a modified trajectory-planning method.
Design/methodology/approach
A rigid-flexible coupling dynamics model of the collaborative robot is established using the finite element and Lagrange methods, and the vibration equation of the robot is derived. Trajectory planning is performed with the excitation force as the optimization objective, and the trajectory planning method is modified to reduce the vibration of the collaborative robot and ensure the precision of the robot terminal.
Findings
The vibration amplitude is reduced by 80%. The maximum torque amplitude of the joint before the vibration suppression reaches 50 N·m. After vibration suppression, the maximum torque amplitude of the joint is 10 N·m, and the resonance phenomenon is eliminated during the operation process. Consequently, the effectiveness of the modified trajectory planning method is verified, where the vibration and residual vibration in the movement of the collaborative robot are significantly reduced, and the positioning accuracy and working efficiency of the robot are improved.
Originality/value
This method can greatly reduce the vibration and residual vibration of the collaborative robot, improve the positioning accuracy and work efficiency and promote the rapid application and development of collaborative robots in the industrial and service fields.