Xueli Wu, Xianghui Lu, Hua Meng, Ran Zhen and Fanhua Meng
The purpose of this paper is to propose a kind of fuzzy adaptive control method to control non‐linear system that has the characteristic of small time delay and fast respond speed.
Abstract
Purpose
The purpose of this paper is to propose a kind of fuzzy adaptive control method to control non‐linear system that has the characteristic of small time delay and fast respond speed.
Design/methodology/approach
The paper analyzes the production process and the actual condition of the preheat process of the plating zinc and painting plastic scribbled of double layer welded pipe that has the small time delay and fast respond speed, and also gives the preheat process mathematical model. Fuzzy adaptive control method with hierarchical structure is used which aims at one non‐linear system that has the characteristic of small time delay and fast responds speed. Through the simulation, it proves the mentioned method is effective to control the temperature system for double layers welded pipe in welding process.
Findings
Based on the mathematical model proposed about the production process and the actual condition of the preheat process, the fuzzy adaptive control method is effective to control the temperature system for double layers welded pipe in welding process.
Research limitations/implications
The paper proposes fuzzy adaptive control method with hierarchical structure which has the basic fuzzy control grade, adaptive adjust grade, and process state judgment grade.
Practical implications
A very useful method in welding process for double layers welded pipe.
Originality/value
The new mathematical model is proposed about the production process, and the new control method is used in the temperature system for double layers welded pipe in welding process.
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Yun Su, Miao Tian, Yunyi Wang, Xianghui Zhang and Jun Li
The purpose of this paper is to study heat and steam transfer in a vertical air gap and improve thermal protective performance of protective clothing under thermal radiation and…
Abstract
Purpose
The purpose of this paper is to study heat and steam transfer in a vertical air gap and improve thermal protective performance of protective clothing under thermal radiation and hot steam.
Design/methodology/approach
An experiment-based model was introduced to analyze heat and moisture transfer in the vertical air gap between the protective clothing and human body. A developed test apparatus was used to simulate different air gap sizes (3, 6, 9, 12, 15, 18, 21 and 24 mm). The protective clothing with different air gap sizes was subjected to dry and wet heat exposures.
Findings
The increase of the air gap size reduced the heat and moisture transfer from the protective clothing to the skin surface under both heat exposures. The minimum air gap size for the initiation of natural convection in the dry heat exposure was between 6 and 9 mm, while the air gap size for the occurrence of natural convection was increased in the wet heat exposure. In addition, the steam mass flux presented a sharp decrease with the rising of the air gap size, followed by a stable state, mainly depending on the molecular diffusion and the convection mass transfer.
Originality/value
This research provides a better understanding of the optimum air gap under the protective clothing, which contributes to the design of optimum air gap size that provided higher thermal protection against dry and wet heat exposures.
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Qurat Ul Ain, Xianghui Yuan and Hafiz Mustansar Javaid
This study investigates the impact of board gender diversity and foreign ownership on innovation in Chinese firms.
Abstract
Purpose
This study investigates the impact of board gender diversity and foreign ownership on innovation in Chinese firms.
Design/methodology/approach
The authors use data for Chinese manufacturing firms listed on the Shanghai and Shenzhen stock exchanges, for a sample over the period 2008–2017. Ordinary least square (OLS) is used as the baseline methodology, with cluster OLS, two-stage Heckman test, Blau index and Shannon index used to address endogeneity issues.
Findings
The results show that gender diversity on the board has a positive effect on corporate innovation as measured by the total number of patent applications, invention patent applications, utility model patent applications and design patent applications. Our findings also provide support for the critical mass participation of female directors on the board being associated with more innovation. They also reveal that innovation output does not vary across state-owned enterprises (SOEs) and non-SOEs. These outcomes reveal that SOEs' advantages, such as easy access to funding and more support of government, are likely offset by their disadvantages, such as different goals and having more agency issues. Because of intense political power and networks in Chinese firms, qualified foreign institutional investors (QFIIs) are less motivated to enhance innovation activities.
Practical implications
This study highlights the role of board gender diversity in enhancing innovation among Chinese manufacturing firms. Our findings provide support for regulatory bodies' role regarding women's participation on the board.
Originality/value
This research adds to literature by addressing the largely ignored questions of whether providing a gender-diverse board enhances innovation, whether critical mass participation has a greater effect on improving firm innovation and whether the influence of women directors varies with ownership structure.
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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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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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Yang Hu, Xianghui Meng, Youbai Xie and Jiazheng Fan
During running-in, the change in the honed cylinder liner surface alters the performance and efficiency of the piston ring-pack system. The present paper, thus, aims to…
Abstract
Purpose
During running-in, the change in the honed cylinder liner surface alters the performance and efficiency of the piston ring-pack system. The present paper, thus, aims to investigate the surface topography and wear and friction evolution of a cylinder liner surface during the running-in tests on a reciprocating ring–liner tribometer under a mixed lubrication regime. After an initial period of rapid wear termed “running-in wear”, a relatively long-term steady-state surface topography can emerge. A numerical model is developed to predict the frictional performance of a piston ring-pack system at the initial and steady-state stages.
Design/methodology/approach
The liner surfaces are produced by slide honing (SH) and plateau honing (PH). The bearing area parameter (Rk family), commonly used in the automotive industry, is used to quantitatively characterize the surface topography change during the running-in process. A wear volume-sensitive surface roughness parameter, Rktot, is used to show the wear evolution.
Findings
The experimental results show that a slide-honed surface leads to reduced wear, and it reduces the costly running-in period compared to the plateau-honed surface. The simulation results show that running-in is a beneficial wear process that leads to a reduced friction mean effective pressure at the steady-state.
Originality/value
To simulate the mixed lubrication performance of a ring–liner system with non-Gaussian roughness, a one-dimensional homogenized mixed lubrication model was established. The real surface topography instead of its statistical properties is taken into account.
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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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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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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.