Jiang Wu, Xiaobo Wang, Xianghui Zhao, Chunbao Zhang and Bo Gao
The purpose of this paper is to explore an application of computer‐aided design and manufacture (CAD/CAM) to a process of electronically surveying a scanned dental cast as a prior…
Abstract
Purpose
The purpose of this paper is to explore an application of computer‐aided design and manufacture (CAD/CAM) to a process of electronically surveying a scanned dental cast as a prior stage to producing a sacrificial pattern for a removable partial denture (RPD) metal alloy framework.
Design/methodology/approach
With the introduction of laser scan technology and commercial reverse engineering software, a standard plaster maxillary dental cast with dentition defect was successfully scanned and created as a STL‐formatted digital cast. With the software, the unwanted undercuts were eliminated based on the desired path of insertion. Parts of the RPD framework were then successfully custom‐designed and combined as a whole.
Findings
A sacrificial pattern was produced by rapid prototyping (RP) method and finally casted with chromium cobalt alloy. With suitable finishing process, both the sacrificial pattern and the casted framework fitted the cast well.
Originality/value
The research indicated the feasibility of creating a library of RPD framework components. It is believed that, in the future, with the advance of the techniques, a totally new platform can be developed for the design and fabrication of custom‐fit RPD framework based on the CAD/CAM/RP system.
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Bo Gao, Jiang Wu, Xianghui Zhao and Hua Tan
This paper aims to improve the efficiency and the quality of metal dental prostheses, reporting on the first patient‐fitted titanium (Ti) complete denture base plate fabricated by…
Abstract
Purpose
This paper aims to improve the efficiency and the quality of metal dental prostheses, reporting on the first patient‐fitted titanium (Ti) complete denture base plate fabricated by integrating the technologies of computer‐aided design and computer‐aided manufacture (CAD/CAM) and laser rapid forming (LRF).
Design/methodology/approach
To make a complete Ti denture base plate, the traditional lost‐wax‐casting technique is commonly used in dentistry. In order to simplify this labor‐intensive process, a new method combined with LRF was invented. Initially, a maxillary edentulous plaster cast was converted to point cloud data by laser scanning system. Subsequently, point cloud data were reconstructed into a 3D solid digital cast, which is stored in standard triangulation language format. Thereafter the 3D denture base was sliced electronically into a sequence of layers defining the regions of the component and, based on it, the complete Ti denture base plate was built layer‐by‐layer using a laser additive manufacturing technology.
Findings
After CAD/CAM/LRF process, the Ti denture base plate was designed and successfully fabricated layer‐by‐layer. After the traditional dental finishing techniques, the complete Ti denture base plate was made and assessed by clinician and patient. The clinical evaluation on quality of fit was judged to be acceptable.
Originality/value
The CAD/CAM/LRF system is a potential candidate to replace the traditional lost‐wax‐casting technique and provides a new platform for the design and manufacturing of custom‐made Ti denture plates and other restorations especially for implant substructure and framework of partial removal of denture.
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Xianghui Meng, Changya Yu, Youbai Xie and Benfu Mei
This paper aims to investigate the lubrication performance of cam/tappet contact during start up. Especially, the thermal insulation effects of coating on the lubrication…
Abstract
Purpose
This paper aims to investigate the lubrication performance of cam/tappet contact during start up. Especially, the thermal insulation effects of coating on the lubrication performance during cold start up process and warm start up process are studied.
Design/methodology/approach
A numerical model for the analysis of thermal elastohydrodynamic lubrication of coated cam/tappet contact is presented. In this model, the Reynolds equation and the energy equations are discretized by the finite difference method and solved jointly.
Findings
During start up, the contact force at cam nose-to-tappet contact decreases with increasing time, while the absolute entrainment velocity has the upward trend. The minimum film thickness, maximum average temperature and friction power loss increase with increasing time, while the coefficient of friction decreases during start up. Because of the thermal insulation effect, the coating can significantly increase the degree of temperature rise. Compared with the uncoated case, the coated cam/tappet results in a lower friction power loss. Generally, the friction power loss in the cold start up process is much higher than that in the warm start up process.
Originality/value
By this study, the lubrication performance and the kinematics and the dynamics of the cam/tappet during start up process are investigated. Meanwhile, the thermal insulation effect of coating is also illustrated. The difference of lubrication performance between cold start up process and warm start up process is analyzed. The results and thermal elastohydrodynamic lubrication method presented in this study can be a guidance in the design of the coated cam/tappet.
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Qurat Ul Ain, Xianghui Yuan, Hafiz Mustansar Javaid, Muhammad Usman and Muhammad Haris
The purpose of this research is to examine whether board gender diversity reduces the agency costs of firms in the context of Chinese listed firms.
Abstract
Purpose
The purpose of this research is to examine whether board gender diversity reduces the agency costs of firms in the context of Chinese listed firms.
Design/methodology/approach
This paper uses a large sample of 23,340 firm-year observations of Chinese listed companies during 2004–2017. The authors use ordinary least squares regressions as the primary methodology with a wide range of methods to control for endogeneity and to check robustness, including the fixed-effect method, instrumental variable approach, lagged gender diversity measures, propensity score matching, Blau index, Shannon index and industry-adjusted measures of agency costs.
Findings
The evidence reveals that the participation of female directors in corporate board reduces agency costs, which correlates with conflicts of interest. Moreover, gender-diverse boards are more effective in state-owned enterprises (SOEs), in which agency issues are more severe. Female directors also provide better monitoring roles in more-developed areas. Finally, corporate boards that have a critical mass of female directors have a greater tendency to reduce agency costs as compared to their token participation. Overall, all findings support the validity of agency theory.
Practical implications
This study shows the economic benefit of female directors in the boardroom by reducing agency costs and by improving firms' governance structure. Regarding the government, which is gradually introducing board gender diversity policies, this study provides valuable pragmatic information for Chinese regulators on this issue.
Originality/value
This study extends the literature by providing evidence that gender diversity in boardroom matters for shareholders' wealth maximization. It provides novel evidence that a critical mass of female directors is more effective in reducing agency costs compared to a single female on the board, and that the effect of gender diversity varies in relation to ownership structure and region.
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Xinyu Wei, Heng Xie, Xianghui Peng and Victor Prybutok
The purpose of this research is to investigate how the consumer’s trusting mechanism influences their behavioral adoption intention in the context of genetic testing.
Abstract
Purpose
The purpose of this research is to investigate how the consumer’s trusting mechanism influences their behavioral adoption intention in the context of genetic testing.
Design/methodology/approach
Based on the technology acceptance theory and trust formation theory, the research posits and develops a comprehensive trust model by integrating trust-related factors that correlate to the consumer’s trusting beliefs and trusting intention. Survey data with 525 respondents allow to test and validate the model.
Findings
The tested model shows that technology institutional trust base, end-user’s cognitive trust base and social influence are significant determinants of trusting beliefs. The findings also reveal that mediation effects of performance expectancy and perceived risks exist in the relationship between trusting beliefs and trusting intention.
Originality/value
The foreseeable positive impact and rapid market growth of emerging healthcare technologies necessitate the strong need to study user acceptance. However, there is a lack of research on how consumers trust and their adoption intention of such innovations. Prior empirical evidence from different contexts and perspectives also show contradictory findings. This research extends the existing technology acceptance literature to a healthcare context, provides an improved generalized understanding of the consumer’s trusting mechanism in emerging biotechnology and discusses practical insights for regulatory authorities, healthcare institutes and medical professionals.
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Kang Yan, Hulin Li, Ning Ding, Dan Jiang and Xianghui Meng
Friction and wear are very important factors in predicting the performance of journal bearings, particularly under heavy load in start-up processes. However, there are few…
Abstract
Purpose
Friction and wear are very important factors in predicting the performance of journal bearings, particularly under heavy load in start-up processes. However, there are few relevant studies on the numerical model. This study aims to establish a transient-mixed lubrication model to predict the performance of journal bearings, focusing on the friction and wear behavior under heavy load during start-up.
Design/methodology/approach
The average Reynold equation, three-dimensional energy equation, shear stress model for friction and Archard model for wear are coupled in the transient model by finite difference method. The linear wear simulation method is bought out to reduce the update times and the calculation time.
Findings
The different start-up accelerations and linear wear times set are compared and discussed, which indicates a reasonable start-up acceleration is necessary for journal bearings under heavy load during start-up, and setting linear wear times is an effective method to reduce the simulation time significantly. Furthermore, the wear profile in the start-up process spreads in both the clearance and circumferential directions, but mainly in the clearance direction, which increases the minimum film thickness and affects the friction performance.
Originality/value
This study is of great significance for the numerical prediction of the transient performance of journal bearings during start-up considering friction and wear.
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Shaoyi Xu, Fangfang Xing, Ruilin Wang, Wei Li, Yuqiao Wang and Xianghui Wang
At present, one of the key equipment in pillar industries is a large rotating machinery. Conducting regular health monitoring is important for ensuring safe operation of the large…
Abstract
Purpose
At present, one of the key equipment in pillar industries is a large rotating machinery. Conducting regular health monitoring is important for ensuring safe operation of the large rotating machinery. Because vibrations sensors play an important role in the workings of the rotating machinery, measuring its vibration signal is an important task in health monitoring. This paper aims to present these.
Design/methodology/approach
In this work, the contact vibration sensor and the non-contact vibration sensor have been discussed. These sensors consist of two types: the electric vibration sensor and the optical fiber vibration sensor. Their applications in the large rotating machinery for the purpose of health monitoring are summarized, and their advantages and disadvantages are also presented.
Findings
Compared with the electric vibration sensor, the optical fiber vibration sensor of large rotating machinery has unique advantages in health monitoring, such as provision of immunity against electromagnetic interference, requirement of less insulation and provision of long-distance signal transmission.
Originality/value
Both contact vibration sensor and non-contact vibration sensor have been discussed. Among them, the electric vibration sensor and the optical fiber vibration sensor are compared. Future research direction of the vibration sensors is presented.
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Yihu Tang, Li Huang and Xianghui Meng
The contact and lubrication performances, which were previously estimated assuming a Gaussian surface, are insufficient due to the non-Gaussian surface characteristics of the…
Abstract
Purpose
The contact and lubrication performances, which were previously estimated assuming a Gaussian surface, are insufficient due to the non-Gaussian surface characteristics of the honing liner. The purpose of this study is to analyze the liner honing surface and examine its effects on the contact and flow performance.
Design/methodology/approach
The fast Fourier transform (FFT) method was used to generate the liner honing texture. Subsequently, an elastoplastic contact model based on boundary element theory was constructed and simulated for the honing surface. The results were compared with those obtained using a Gaussian surface. In addition, flow factors of the honing surfaces were also compared.
Findings
The contact pressure and flow factors demonstrate significant disparities when dealing with non-Gaussian surfaces. In the deterministic model, the pressure exhibits considerably diminished magnitudes and a more evenly distribution. Moreover, when the gap between surfaces is narrow, the discrepancy in flow factor across different directions on the real honing surface becomes more prominent compared with the Gaussian surface.
Originality/value
The model incorporates the influence of the non-Gaussian honing surface, thereby enabling more accurate prediction.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2023-0198/
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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.
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Tao Li, Jiajun Shu, Yue Li, Yanlong Wang and Bo Liu
This study aims to provide a reference basis for waterproofing for the long-term safe operation of shield tunnels. Shielding subways in the long-term operation of tunnel tube…
Abstract
Purpose
This study aims to provide a reference basis for waterproofing for the long-term safe operation of shield tunnels. Shielding subways in the long-term operation of tunnel tube seams leads to opening, dislocation and other issues, which in turn cause the tube sealing gasket to break and ultimately cause water seepage, and the existing symmetrical sealing gasket arrangement cannot meet the waterproofing requirements of the tunnel structure.
Design/methodology/approach
First, we carry out an indoor “one-seam” hydrostatic test to quantitatively determine the waterproofing performance of symmetric and four asymmetric arrangements of gaskets. And the arrangement with the best stability and waterproofing performance is selected. Second, we establish a three-dimensional numerical seepage model for the waterproof failure of gaskets with different arrangements, which mechanistically explains the whole course of the gradual failure of the waterproof performance of gaskets with the wedging of water. Finally, we compare and analyze the experimental results with the numerical results to verify the reliability of the different analysis methods.
Findings
The results of the research show that the gasket will undergo four stages: the initial stage, deformation stage, wedging stage, and breakthrough stage during the continuous wedging process of the water body. Compared with the symmetric arrangement of the gasket, the asymmetric arrangement of the effective contact part of the gasket stress wave peaks and troughs is smaller, the deformation stage of the ability to resist the deformation of the water pressure is stronger, and the role of the water pressure between the two sealing gaskets of the stress path is less likely to be damaged.
Research limitations/implications
The current test can't fully reproduce real engineering site conditions as it ignores factors like temperature, time and aging during waterproofing tests and lacks tests based on actual application. Only one – seam test is done, lacking research on other seams. The current seepage model has difficulty reflecting some details and needs refinement.
Practical implications
The study focuses on the tube sheet joint problem in underground tunnels and proposes four asymmetric gasket arrangements, which are tested and analysed using a variety of methods. The results show that the asymmetric arrangement has a slower decline in waterproofing capacity and better stability, providing a new method and basis for solving tunnel waterproofing problems.
Originality/value
The study focuses on the tube sheet joint problem in underground tunnels and proposes four asymmetric gasket arrangements, which are tested and analysed using a variety of methods. The results show that the asymmetric arrangement has a slower decline in waterproofing capacity and better stability, providing a new method and basis for solving tunnel waterproofing problems.