Xiaocui Xin, Yunxia Wang, Zhaojie Meng, Hao Liu, Yunfeng Yan and Fengyuan Yan
This paper aims to focus on studying the addition of nano-tungsten disulfide (WS2) on fretting wear performance of ultra-high-molecular-weight-polyethylene (UHMWPE).
Abstract
Purpose
This paper aims to focus on studying the addition of nano-tungsten disulfide (WS2) on fretting wear performance of ultra-high-molecular-weight-polyethylene (UHMWPE).
Design/methodology/approach
In this study, the effect of WS2 content on fretting wear performance of UHMWPE was investigated. The fretting wear performance of the UHMWPE and WS2/UHMWPE nanocomposites were evaluated on oscillating reciprocating friction and wear tester. The data of the friction coefficient and the specific wear rate were obtained. The worn surfaces of composites were observed. The transfer film and its component were analyzed.
Findings
With the addition of 0.5% WS2, the friction coefficient and specific wear rate increased. With the content increased to 1% and 1.5%, the friction coefficient and specific wear rate decreased. The lowest friction coefficient and specific wear rate were obtained with the addition of 1.5% nano-WS2. Continuingly increasing content, the friction coefficient and wear rate increased but lower than that of pure UHMWPE.
Research limitations/implications
The research indicated the fretting wear performance related to the content of nano-WS2 with the incorporation of WS2 into UHMWPE.
Practical implications
The result may help to choose the appropriate content.
Originality/value
The main originality of the research is to reveal the fretting behavior of UHMWPE and WS2/UHMWPE nanocomposites. It makes us realize the nano-WS2 had an effect on the fretting wear performance of UHMWPE.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0151/
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Zhaojie Meng, Yunxia Wang, Xiaocui Xin, Hao Liu, Yunfeng Yan and Fengyuan Yan
The purpose of this study is to examine the fretting wear property of ultra-high molecular weight polyethylene (UHMWPE)-based composites reinforced by different content of…
Abstract
Purpose
The purpose of this study is to examine the fretting wear property of ultra-high molecular weight polyethylene (UHMWPE)-based composites reinforced by different content of attapulgite.
Design/methodology/approach
A series of composites were prepared by a hot-pressing method. Fretting tests were carried out using an SRV-IV oscillating reciprocating friction wear tester with a load of 10 N and a frequency of 100 Hz. The morphology of the fracture structure and the worn surface was observed by field-emission scanning electron microscopy, X-ray diffraction and a non-contact three dimensional surface profiler.
Findings
With the addition of attapulgite, the microstructure of the composites become more regular, and their heat resistance improved. Furthermore, the friction coefficient and the specific wear rate of the composites with lower filler content reduced compared with that of neat UHMWPE, and the optimum filler content is 1 per cent.
Originality/value
The study investigated the fretting resistance mechanism of the attapulgite in the UHMWPE matrix. The results could help to provide some experimental evidence for the broader application of silicates on the fretting wear resistance of polymers.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0420/
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Yunchu Yang, Hengyu Wang, Hangyu Yan, Yunfeng Ni and Jinyu Li
The heat transfer properties play significant roles in the thermal comfort of the clothing products. The purpose of this paper is to find the relationship between heat transfer…
Abstract
Purpose
The heat transfer properties play significant roles in the thermal comfort of the clothing products. The purpose of this paper is to find the relationship between heat transfer properties and fabrics' structure, yarn properties and predict the effective thermal conductivity of single layer woven fabrics by a parametric mathematical model.
Design/methodology/approach
First, the weave unit was divided into four types of element regions, including yarn overlap regions, yarn crossing regions, yarn floating regions and pore regions. Second, the number and area proportion of each region were calculated respectively. Some formulas were created to calculate the effective thermal conductivity of each element region based on serial model, parallel model or series–parallel mixing model. Finally, according to the number and area proportion of each region in weave unit, the formulas were established to calculate the fabric overall effective thermal conductivity in thickness direction based on the parallel models.
Findings
The influences of yarn spacing, yarn width, fabric thickness, the compressing coefficients of air layers and weave type on the effective thermal conductivity were further discussed respectively. In this model, the relationships between the effective thermal conductivity and each parameter are some polynomial fitting curves with different orders. Weave type affects the change of effective thermal conductivity mainly through the numbers of different elements and their area ratios.
Originality/value
In this model, the formulas were created respectively to calculate the effective thermal conductivity of each element region and whole weave unit. The serial–parallel mixing characteristics of yarn and surrounding air are considered, as well as the compression coefficients of air layers. The results of this study can be further applied to the optimal design of mixture fabrics with different warp and filling yarn densities or different yarn thermal properties.
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Jinyu Li, Hangyu Yan, Yunfeng Ni, Linlin Fu and Yunchu Yang
At present, electrical heating clothing is widely used to keep ourselves warm at low temperature. The purpose of this paper is to explore the heat transfer performance of…
Abstract
Purpose
At present, electrical heating clothing is widely used to keep ourselves warm at low temperature. The purpose of this paper is to explore the heat transfer performance of electrical heating fabric and the thermal comfort of human skin at low temperature.
Design/methodology/approach
The combined model of skin-electrical heating fabric system was established to simulate human skin tissue wearing electrical heating clothing. A series of simulation experiments are designed on the basis of verifying the effectiveness of the combined model. The temperature distribution inside the combined model and on the skin surface under different heating powers is simulated and analyzed. At the same time, the influence of ambient temperature on the thermal performance of electrical heating fabric was explored.
Findings
The skin model with blood vessels reflected the temperature change of human skin wearing electrical heating clothing. The higher the heating power of the electrical heating fabric was, the greater the temperature of the skin surface changed, the faster the temperature rose and the longer the time required to reach the stable state would be. After the heating element was electrified, it had the greatest effect on the average temperature of the epidermis and dermis, had smaller effect on the average temperature of subcutaneous layer and had little effect on the temperature of blood vessels. When the heating power was the same, the higher the ambient temperature was, the more obvious the heating effect of electrical heating fabric was. Electrical heating fabrics with different heating powers were suitable for different ambient temperature ranges.
Originality/value
A reasonable and effective evaluation method for the thermal comfort of electrical heating fabric was provided by establishing the skin model and combined model of the skin-electrical heating fabric system. It provides a reference for the design and application of electrical heating clothing.
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Shulin Xu, Xue Wan, Yunfeng Li and Jingrui Yan
How to realize social capital “exit from virtual to real” has become not only a hot issue that elicited economists' and the practice field's concern but also a key economic…
Abstract
Purpose
How to realize social capital “exit from virtual to real” has become not only a hot issue that elicited economists' and the practice field's concern but also a key economic structure problem that the government has to solve urgently. The main purpose of this study is to explore effective methods for social capital to “exit from virtual to real”.
Design/methodology/approach
The study investigates the realization path of social capital's “exit from virtual to real” by using firm theory and data from the National Bureau of Statistics in China. Provincial panel data are also utilized to empirically test the impact of social capital's de-realization to virtual (or from virtual to real) on economic development and whether the path of social capital “from virtual to real” is valid.
Findings
This study analyzes the development status of social funds serving the real economy and the hazards of social funds' “exit from real to virtual,” which are mainly viewed as eroding the development of the real economy and causing operating difficulties. On the basis of firm theory, the internal motivation for why social funds flow to the real economy is explored from the perspectives of the needs of the real economy, price and profit. Moreover, this study designs a path for returning social capital to the real economy.
Practical implications
Overall, expanding aggregate demand while providing an effective supply and implementing a proactive fiscal policy that focuses on structural tax cuts while keeping margins in the virtual economy are appropriate for promoting the competitiveness of the real economy.
Originality/value
This study explores a topic, namely, social capital “exit from virtual to real,” that has received little attention. It provides an in-depth discussion of the following questions. (1) What is the current situation of social capital serving the real economy? (2) What kind of harm can social capital bring to society? What are the inherent barriers to the flow of social capital to the real economy? (3) At this stage, how can the effective transformation of social capital into the real economy be realized? The findings help in understanding the sustainable entrepreneurship concept, particularly in developing countries.
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Hongyue Wu, Yunfeng Chen, Robert F. Cox and Ruoyu Jin
Lack of trust in construction projects will lead to poor project performance or project failure, indicating the importance of trust-building. Existing studies have developed…
Abstract
Purpose
Lack of trust in construction projects will lead to poor project performance or project failure, indicating the importance of trust-building. Existing studies have developed various trust models, while most studies covered limited trust factors, failed to clarify their meanings and relationships or lacked qualitative or quantitative evidence. Thus, this study aims to develop a measurement model of trust in construction projects with theoretical justification as well as qualitative and quantitative data.
Design/methodology/approach
A literature review was conducted to identify conceptual types, factors and indicators of trust. Individual interviews and focus groups were performed to test the proposed framework with qualitative data. A survey and confirmatory factor analysis (CFA) method were utilized to build the measurement model of trust using quantitative data in BIM-assisted projects.
Findings
The proposed trust framework covered the four conceptual types, four factors (integrity, competency, benevolence and commitment) and 13 indicators, supported by the results of interviews and focus groups. The measurement model of trust from CFA results supported the significant, positive, and one-to-one relationships between 13 indicators and four factors of trust in BIM-assisted projects.
Originality/value
Theoretically, the study provides new insights into the multi-dimensional nature of trust. In practice, the findings could facilitate trustors and trustees to better understand, build, measure and enhance trust in construction projects.
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Yunfeng Li, Ruoxuan Li, Ao Tian, Xinming Xu and Hang Zhang
This paper aims to study the influence of different seal structure parameters and working conditions on the air-oil two-phase flow characteristics and leakage characteristics of…
Abstract
Purpose
This paper aims to study the influence of different seal structure parameters and working conditions on the air-oil two-phase flow characteristics and leakage characteristics of the seal cavity in the bearing cavity of the aero-engine spindle bearing tester.
Design/methodology/approach
In this paper, the VOF method and RNG k-ε turbulence model are used to explore the flow characteristics and leakage characteristics of the labyrinth seal cavity of an aero-engine spindle bearing tester under the condition of air-oil two-phase flow.
Findings
The distribution of the lubricating oil is related to the sealing clearance and the air-oil ratio. The amount of oil leakage increases with increasing of sealing chamber clearance, air-oil ratio and inlet velocity and decreases with increasing curvature and speed. The amount of air leakage increases with sealing clearance and inlet velocity.
Originality/value
In comparison to the pure air-phase flow field, the air-oil two-phase flow field can more accurately simulate the lubricating oil flow in the sealing chamber.
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Cong Li, YunFeng Xie, Gang Wang, XianFeng Zeng and Hui Jing
This paper studies the lateral stability regulation of intelligent electric vehicle (EV) based on model predictive control (MPC) algorithm.
Abstract
Purpose
This paper studies the lateral stability regulation of intelligent electric vehicle (EV) based on model predictive control (MPC) algorithm.
Design/methodology/approach
Firstly, the bicycle model is adopted in the system modelling process. To improve the accuracy, the lateral stiffness of front and rear tire is estimated using the real-time yaw rate acceleration and lateral acceleration of the vehicle based on the vehicle dynamics. Then the constraint of input and output in the model predictive controller is designed. Soft constraints on the lateral speed of the vehicle are designed to guarantee the solved persistent feasibility and enforce the vehicle’s sideslip angle within a safety range.
Findings
The simulation results show that the proposed lateral stability controller based on the MPC algorithm can improve the handling and stability performance of the vehicle under complex working conditions.
Originality/value
The MPC schema and the objective function are established. The integrated active front steering/direct yaw moments control strategy is simultaneously adopted in the model. The vehicle’s sideslip angle is chosen as the constraint and is controlled in stable range. The online estimation of tire stiffness is performed. The vehicle’s lateral acceleration and the yaw rate acceleration are modelled into the two-degree-of-freedom equation to solve the tire cornering stiffness in real time. This can ensure the accuracy of model.
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Kangjie Cheng, Yunfeng Liu, Chunyan Yao, Wenquan Zhao and Xu Xu
The purpose of this study is to obtain a titanium mandibular implant that possesses a personalized external shape for appearance recovery, a supporting structure for physiological…
Abstract
Purpose
The purpose of this study is to obtain a titanium mandibular implant that possesses a personalized external shape for appearance recovery, a supporting structure for physiological loading and numerous micro-pores for accelerating osseointegration.
Design/methodology/approach
A three-dimensional intact mandibular model of a beagle dog was created from cone-beam computerized tomography scans. A segment of the lower jaw bone was resected and replaced by a personalized implant with comprehensive structures including a customized external shape, supporting structures and micro-pores, which were designed by topology optimization. Then with FEM analysis, the stress, displacement distribution and compliance of the designed implant were compared with the non-optimized model. The weight of the optimized implant that was fabricated by SLM with titanium alloy powder was measured and contrasted with the predicted non-optimized model for evaluating the viability of the design.
Findings
The FEM results showed the peaks of von Mises stress and displacement on the optimized implant were much lower than those of the implant without optimization. With topology optimization, the compliance of the implant decreased significantly by 53.3 per cent, and a weight reduction of 37.2 per cent could be noticed.
Originality/value
A design strategy for personalized implant, with comprehensive structures and SLM as the fabrication method, has been developed and validated by taking a canine mandible as the case study. With comprehensive structures, the implant presented good biomechanical behaviors thanks to the most appropriate supporting structures obtained by optimal design. The topological optimal design combined with SLM printing proved to be an effective method for the design and fabrication of personalized implant with complex structures.
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The supervisory system of modern Chinese companies has basically adopted the supervisory board system of countries of continental law system. Certain disadvantages, however, exist…
Abstract
Purpose
The supervisory system of modern Chinese companies has basically adopted the supervisory board system of countries of continental law system. Certain disadvantages, however, exist in the system and the purpose of this paper is to identify those disadvantages and suggest changes.
Design/methodology/approach
This paper draws upon a consideration of the policy objectives and assesses the practical gaps in implementation through a consideration of case‐studies.
Findings
There are many functions and manifest functions of the supervisory board system of modern Chinese companies. Certain disadvantages, however, exist in this system: the postmortem nature of supervision causes the failure of timely supervision, and the externality of supervision leads to information asymmetry. Meanwhile, the functions of supervisory board are weakened by the fact that the law does not impose positive qualification requirements for supervisors and that the law has not laid down specific regulations for the effective deliverance of the company's financial and business information to the supervisors and the supervisory board. In order to guarantee the realization of the functions of the company's supervisory board, we should perfect in legislation the supervisory board system of our country, and at the same time strengthen the construction of company supervisory board system in our country and other relevant supervisory mechanism and supporting systems. Originality/value – This paper presents an analysis of “gaps” in policy implementation and might influence reform in this area.