Peng-hui Wu, Xiaojun Zhou, Chenlong Yang, Haoliang Lv, Tianhao Lin and Xuelei Wu
The purpose of this paper is to reduce the drag loss and study the effects of operating conditions and groove parameters such as flow rate and temperature of automatic…
Abstract
Purpose
The purpose of this paper is to reduce the drag loss and study the effects of operating conditions and groove parameters such as flow rate and temperature of automatic transmission fluid, clearance between plates, groove depth and groove ratio on the drag torque of a wet clutch for vehicles, parametric analysis of the drag torque model of wet multi-plate friction clutch with groove consideration.
Design/methodology/approach
Both experimental and numerical research was carried out in this work. Parametric groove models, full film lubrication flow model and pressure distribution model are established to investigate the effects of the grooves on drag torque of a wet clutch. Multigrid method is used to simplify the solution.
Findings
In this paper, a drag torque model of a wet multi-plate friction clutch based on the basic theory of viscous fluid dynamics is examined through experimental and numerical methods that take grooves into account, and the change trend of drag torque with operating conditions and groove parameters is analyzed.
Originality/value
Multigrid method is used to solve the governing equations, which simplifies the solution process because of the restrictions and interpolation operations between the adjacent layers of coarser and fine grids. These works provide insight into the effect regularity of operating conditions and groove parameters on drag torque of a wet multi-plate friction clutch. Furthermore, variable test conditions and sufficient experimental data are the main functions in the experimental research.
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Xiaojun Zhou, Lifeng Xi and Jay Lee
The purpose of this paper is to develop a dynamic opportunistic maintenance policy for a continuously monitored multi‐unit series system with integrating imperfect effect into…
Abstract
Purpose
The purpose of this paper is to develop a dynamic opportunistic maintenance policy for a continuously monitored multi‐unit series system with integrating imperfect effect into maintenance activities.
Design/methodology/approach
Based on the hybrid hazard rate recursion rule, an imperfect maintenance model for a continuously monitored single‐unit system was proposed. Then by introducing the “set‐up cost” concept, a dynamic opportunistic maintenance (OM) policy for multi‐unit‐series‐systems was developed. The optimal maintenance activities were determined by maximizing the short‐term cumulative OM cost saving for the continuously monitored system. A numerical example is given to show how the proposed dynamic OM policy proceeded.
Findings
The simulation results imply that the proposed policy is better than the policy to maintain the system units separately and the policy to maintain the system units together.
Practical implications
The proposed dynamic maintenance policy can fulfill the real plant environment that maintenance action is always imperfect and maintenance information is only available over a short term. Under this policy, the maintenance manager can easily and quickly adjust the maintenance schedule at any moment according to the working condition of the system.
Originality/value
The proposed model in this paper integrates the imperfect maintenance effect into condition‐based predictive maintenance, and the system maintenance schedule is dynamically determined based on the short‐term information of the system.
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Yuejian Zhou, Xiaoshan Liu, Guoqiu He, Zhiqiang Zhou, Yiping Liao, Yinfu Liu and Xiaojun Xu
This paper aims to investigate the effect of Cu content and T6 heat treatment on the mechanical properties and the tribological performance of SiCp/Al-Si-Cu-Ni-Mg hybrid…
Abstract
Purpose
This paper aims to investigate the effect of Cu content and T6 heat treatment on the mechanical properties and the tribological performance of SiCp/Al-Si-Cu-Ni-Mg hybrid composites at an elevated temperature.
Design/methodology/approach
The stir casting method was used to synthesize SiCp/Al-12Si-xCu-1Ni-1Mg (x = 2, 3, 3.5, 4, 4.5, 5 Wt.%) composites containing 20 vol% SiC. The hardness and tensile strength of the aluminum matrix composites (AMCs) at room temperature and elevated temperature were studied, and the wear mechanism was investigated using scanning electron microscopic and energy dispersive spectroscopy.
Findings
Results indicate that the hardness and tensile strength of the AMCs are affected significantly by T6 heat treatment and Cu content. The high-temperature friction and wear mechanism of AMCs is the composite wear mechanism of oxidation wear, adhesion wear, abrasive wear, peeling wear, high-temperature softening and partial melting. Among them, adhesion wear, high-temperature matrix softening and local melting are the main wear mechanisms.
Originality/value
The influence mechanism of Cu content on the hardness, tensile strength and high temperature resistance of AMCs was explained by microstructure. And the results further help to explore the application of AMCs in high temperature.
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Xiaojun Wu, Zhongyun Zhou and Shouming Chen
Artificial intelligence (AI) applications pose a potential threat to users' data security and privacy due to their high data-dependence nature. This paper aims to investigate an…
Abstract
Purpose
Artificial intelligence (AI) applications pose a potential threat to users' data security and privacy due to their high data-dependence nature. This paper aims to investigate an understudied issue in the literature, namely, how users perceive the threat of and decide to use a threatening AI application. In particular, it examines the influencing factors and the mechanisms that affect an individual’s behavioral intention to use facial recognition, a threatening AI.
Design/methodology/approach
The authors develop a research model with trust as the key mediating variable by integrating technology threat avoidance theory, the theory of planned behavior and contextual factors related to facial recognition. Then, it is tested through a sequential mixed-methods investigation, including a qualitative study (for model development) of online comments from various platforms and a quantitative study (for model validation) using field survey data.
Findings
Perceived threat (triggered by perceived susceptibility and severity) and perceived avoidability (promoted by perceived effectiveness, perceived cost and self-efficacy) have negative and positive relationships, respectively, with an individual’s attitude toward facial recognition applications; these relationships are partially mediated by trust. In addition, perceived avoidability is positively related to perceived behavioral control, which along with attitude and subjective norm is positively related to individuals' intentions to use facial recognition applications.
Originality/value
This paper is among the first to examine the factors that affect the acceptance of threatening AI applications and how. The research findings extend the current literature by providing rich and novel insights into the important roles of perceived threat, perceived avoidability, and trust in affecting an individual’s attitude and intention regarding using threatening AI applications.
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Ziao Huang, Xiaoshan Liu, Guoqiu He, Zhiqiang Zhou, Bin Ge, Peiwen Le, Jiaqi Pan and Xiaojun Xu
This study aims to understand the multiaxial fretting fatigue, wear and fracture characteristics of 35CrMoA steel under the elliptical loading path.
Abstract
Purpose
This study aims to understand the multiaxial fretting fatigue, wear and fracture characteristics of 35CrMoA steel under the elliptical loading path.
Design/methodology/approach
By keeping the contact pressure and torsional shear cyclic stress amplitude unchanged; the axial cyclic stress amplitude varied from 650 MPa to 850 MPa. The fretting fatigue test was carried out on MTS809 testing machine, and the axial cyclic strain response and fatigue life of the material were analyzed. The fretting zone and fracture surface morphology were observed by scanning electron microscope. The composition of wear debris was detected by energy dispersive X-ray spectrometer.
Findings
In this study, with the increase of axial stress amplitude, 35CrMoA steel will be continuously softened, and the cyclic softening degree increases. The fretting fatigue life decreases unevenly. The fretting scars in the stick region are elongated in the axial direction. The area of fracture crack propagation zone decreases. In addition, the results indicate that wear debris in the slip region is spherical and has higher oxygen content.
Originality/value
There were few literatures about the multiaxial fretting fatigue behavior of 35CrMoA steel, and most scholars focused on the contact pressure. This paper reveals the effect of axial cyclic stress on fretting fatigue and wear of 35CrMoA steel under the elliptical loading path.
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Yinfu Liu, Guoqiu He, Xiaoshan Liu, Jiaqi Pan, Zhiqiang Zhou, Yiping Liao, Qiao He and Xiaojun Xu
To improve the high-temperature wear properties of the SiCp/A359 composite, foamed iron-reinforced SiCp/A359 composite (A359–SiCp/Fe) is prepared. The purpose of this study is to…
Abstract
Purpose
To improve the high-temperature wear properties of the SiCp/A359 composite, foamed iron-reinforced SiCp/A359 composite (A359–SiCp/Fe) is prepared. The purpose of this study is to investigate the tribological behavior and mechanism of the A359–SiCp/Fe composites at different temperatures (100–500 °C) and loads (7 N, 10 N and 12 N).
Design/methodology/approach
The A359–SiCp/Fe composite was fabricated by vacuum-assisted infiltration. The dry sliding tribological behaviors of A359–SiCp/Fe composite were investigated using the ball-on-disc-type tribometer. The worn surface and wear morphology of the longitudinal section were examined using field emission scanning electron microscopy and metallographic microscope.
Findings
The critical transition temperature for severe wear in A359–SiCp/Fe composite was 50–100 °C higher than in SiCp/A359 composite. Foamed iron prevents exfoliation cracks from penetrating deeper into the matrix. The friction coefficient stability of the A359–SiCp/Fe composite was higher than the unreinforced composite at elevated temperatures. With the increase in temperature, the friction-affected layer was severely worn, and the wear mechanism transferred from abrasion and delamination to oxidation and plastic flow, respectively.
Originality/value
The preparation procedure for aluminum matrix composites reinforced with foamed metal has been less reported, and the research on the tribological behavior and mechanism of A359–SiCp/Fe composite at various temperatures is insufficient. The foamed iron structure considerably enhances the wear properties of SiCp/A359 composite in elevated temperature conditions.
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Xiaojun Yuan, Yinjie Shen and Haigang Zhou
This paper aims to identify how house price affects household consumption.
Abstract
Purpose
This paper aims to identify how house price affects household consumption.
Design/methodology/approach
The authors use a micro-level data set that tracks the house price and consumption of a vast number of households over a period of four years. OLS regression is the main econometric method.
Findings
The authors document robust evidence that an increase in house prices stimulates household consumption, regardless of whether a household owns or rents. Moreover, the authors find that both acquiring and losing homeownership negatively affects household consumption. Further investigation suggests significant regional heterogeneity in the relationship between house prices and household consumption.
Originality/value
This is one of the first studies examining the relationship between house price and household consumption in China using micro-level data. Given the uniqueness of the Chinese housing market and China’s fast-growing consumption rate, the study contributes new evidence to the long-lasting debate.
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Xiaojun Wu, Peng Li, Jinghui Zhou and Yunhui Liu
Scattered parts are laid randomly during the manufacturing process and have difficulty to recognize and manipulate. This study aims to complete the grasp of the scattered parts by…
Abstract
Purpose
Scattered parts are laid randomly during the manufacturing process and have difficulty to recognize and manipulate. This study aims to complete the grasp of the scattered parts by a manipulator with a camera and learning method.
Design/methodology/approach
In this paper, a cascaded convolutional neural network (CNN) method for robotic grasping based on monocular vision and small data set of scattered parts is proposed. This method can be divided into three steps: object detection, monocular depth estimation and keypoint estimation. In the first stage, an object detection network is improved to effectively locate the candidate parts. Then, it contains a neural network structure and corresponding training method to learn and reason high-resolution input images to obtain depth estimation. The keypoint estimation in the third step is expressed as a cumulative form of multi-scale prediction from a network to use an red green blue depth (RGBD) map that is acquired from the object detection and depth map estimation. Finally, a grasping strategy is studied to achieve successful and continuous grasping. In the experiments, different workpieces are used to validate the proposed method. The best grasping success rate is more than 80%.
Findings
By using the CNN-based method to extract the key points of the scattered parts and calculating the possibility of grasp, the successful rate is increased.
Practical implications
This method and robotic systems can be used in picking and placing of most industrial automatic manufacturing or assembly processes.
Originality/value
Unlike standard parts, scattered parts are randomly laid and have difficulty recognizing and grasping for the robot. This study uses a cascaded CNN network to extract the keypoints of the scattered parts, which are also labeled with the possibility of successful grasping. Experiments are conducted to demonstrate the grasping of those scattered parts.
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XiaoJun Yuan, Aslihan Gizem Korkmaz and Haigang Zhou
In China, having a home before getting married is viewed as being a crucial indicator of the sincerity of romance. Despite recent increases in housing costs, men who have their…
Abstract
Purpose
In China, having a home before getting married is viewed as being a crucial indicator of the sincerity of romance. Despite recent increases in housing costs, men who have their homes ready for marriage stand out in the marriage market. This study aims to explore the association between readiness to marry, marriage age and the home that men purchase prior to marriage using the China Labor-force Dynamics Survey, the first countrywide follow-up survey with the theme of labor force.
Design/methodology/approach
The authors suggest new standards for determining the marital residence. In addition, contrary to the existing literature, which focuses on “Sheng Nu” (women who do not marry by the traditional marriage age in China), the authors focus on “Sheng Nan” (men who do not marry by the traditional marriage age in China).
Findings
The results show that men who own a house before marriage are reluctant to get married. The authors document robust evidence that the preexistence of the marital house decreases the willingness to marry and postpones the marriage date, regardless of location and time.
Originality/value
The authors document robust evidence that the preexistence of the marital house decreases the willingness to marry and postpones the marriage date, regardless of location and time.
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Caiming Zhang, Xiaojun Xu and Hong Chen
The purpose of this paper is to review the current research on theoretical foundations and applications for CPS from 2017 to 2019 including the applications in library.
Abstract
Purpose
The purpose of this paper is to review the current research on theoretical foundations and applications for CPS from 2017 to 2019 including the applications in library.
Design/methodology/approach
This paper is designed in six parts as Introduction, Literature review, Theoretical foundations of CPS, Applications of CPS, CPS’s application in library and Conclusion. The authors review 70 papers and classify them as the above six parts. The authors collected 70 papers from 2017 to 2019 in the academic databases.
Findings
This paper reviews 70 papers regarding theoretical foundations and applications for CPS from 2017 to 2019 in the academic databases aiming to provide scholars and practitioners with a comprehensive overview. The contents of the papers in each research category are summarized from theoretical foundations and applications including the CPS applications in library.
Originality/value
A main contribution of this review paper is that it summarizes the current state-of-the-art theoretical foundations and applications for CPS and in libraries systematically.