Yangtao Xing, Fugang Zhai, Shengnan Li and Peng Gui
This paper aims to study the deformation mechanism of polytetrafluoroethylene (PTFE) oil seal under a wide temperature range cycle.
Abstract
Purpose
This paper aims to study the deformation mechanism of polytetrafluoroethylene (PTFE) oil seal under a wide temperature range cycle.
Design/methodology/approach
This study categorizes the oil seal operation into three states: assembly, heating-up and cooling. The deformation equation for the oil seal is developed for each state, considering the continuity between them. The investigation of the oil seal’s deformation trends and mechanisms is performed using the ANSYS Workbench.
Findings
The assembling process results in a radial shrinkage of the skeleton, causing the centroid to move toward the axis. During heating-up, the outer diameter of the skeleton slightly expands, whereas the inner diameter sharply contracts toward the axis, leading to a further reduction in the centroid’s distance from the axis. Upon cooling, both the inner and outer diameters continue to contract toward the axis, causing the centroid to persist in its movement toward the axis. Consequently, after undergoing a heating-up and cooling cycle ranging from 20°C to 180°C, the outer diameter of the PTFE oil seal reduces by 0.92 mm from its original deformation, ensuring minimal contact between the skeleton and housing. As a result of the reduced static friction torque at the skeleton, the oil seal rotates along the shaft.
Originality/value
The deformation mechanism of PTFE oil seals under a wide temperature range cycle was investigated, aiming to address the concerns related to the rotation along the shaft and leakage.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2023-0142/
Details
Keywords
Yangtao Xing, Fugang Zhai, Shengnan Li, Xiaonan Wang and Zhiqiang He
This study aims to investigate the causes of leakage in radial oil seals under dynamic eccentricity, elucidate the influence of operating parameters on leakage failure and develop…
Abstract
Purpose
This study aims to investigate the causes of leakage in radial oil seals under dynamic eccentricity, elucidate the influence of operating parameters on leakage failure and develop methods for predicting and preventing such leakage.
Design/methodology/approach
Based on the principle of cam motion and considering viscoelasticity, develops a motion model of the compression and release of the shaft seal and proposes a method to determine its failure. In addition, this study quantifies the leakage gap and formulates a quantitative calculation model to accurately determine the location and shape parameters of the leakage gap.
Findings
Leakage gaps predominantly occur during the release phase of the shaft seal. Their presence can be identified by comparing the descending times of the seal and the shaft during this phase. An increase in rotation speed and eccentricity heightens the likelihood of gap formation, with both the dimensions and leakage rate of the gap increasing as these factors escalate. Eccentricity, in particular, has a more pronounced effect on gap formation.
Originality/value
This study clarifies the failure mechanisms of radial oil seals under dynamic eccentricity and introduces a criterion for identifying leakage gaps, providing valuable theoretical guidance for the design and optimization of radial oil seals.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0192/.
Details
Keywords
Fugang Zhai, Shengnan Li and Yangtao Xing
This paper aims to study the motion trajectory of the oil seal for shaft in eccentric state and derive equation of lip motion trajectory.
Abstract
Purpose
This paper aims to study the motion trajectory of the oil seal for shaft in eccentric state and derive equation of lip motion trajectory.
Design/methodology/approach
This paper analyzes the force during the motion of the eccentric lip by considering the material viscoelasticity, and a cam-plate mechanism is established as an equivalent model for the motion between the shaft and the lip; according to this, the equation of lip motion trajectory is derived.
Findings
The trajectory of the lip lags that of the shaft in the eccentric state because the viscoelasticity-affected lip recovery velocity is lower than the shaft recovery speed. The lip trajectory enters the lag phase earlier and the lag phase’s duration is longer with the increase of the eccentricity and rotational speed, because the deviation of the recovery velocities between the lip and the shaft will be exacerbated.
Originality/value
Innovatively, by considering the viscoelasticity of the material, the cam-plate mechanism is used to equivalent the motion of the shaft-lip to derive the equation for the radial motion trajectory of the eccentric lip. The regularity of lip motion is the key to determining the performance of oil seals, and the eccentric lip trajectory research method revealed in this paper provides a research basis for the performance research and optimization of eccentric oil seals.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2023-0161/
Details
Keywords
Hui Zhao, Shengnan Li, Hongyu Yang and Quan Zhou
Variable fractional delay filtering is an important technology in signal processing; the research shows that all-pass variable fractional delay (VFD) filters achieve higher design…
Abstract
Purpose
Variable fractional delay filtering is an important technology in signal processing; the research shows that all-pass variable fractional delay (VFD) filters achieve higher design accuracy than FIR VFD filters; therefore, the design, analysis and implementation of all-pass VFD filters are of great importance.
Design/methodology/approach
In this paper, a two-stage approach for the design of general 1-D stable VFD all-pass filters is proposed. The method takes the desired group delay range [N−1, N], where N is the filter order.
Findings
The design algorithm is decomposed into two design stages: first, a set of fixed delay all-pass filters are designed by minimizing a set of objective functions defined in terms of approximating error criterion and filter stability constraint. Then, the design result is determined by fitting each of the fixed delay all-pass filter coefficients as 1-D polynomials. A design example together with its comparisons with those of the recent literature studies is given to justify the effectiveness of the proposed design method.
Originality/value
An illustrating design example shows that the method proposed can achieve better filter performances than the existing ones.
Details
Keywords
Gehan Wishwajith Premathilake, Hongxiu Li, Chenglong Li, Yong Liu and Shengnan Han
Humanoid social robots (HSRs) are an innovative technology revitalizing various service sectors, such as the hospitality industry. However, limited research has explored how…
Abstract
Purpose
Humanoid social robots (HSRs) are an innovative technology revitalizing various service sectors, such as the hospitality industry. However, limited research has explored how anthropomorphic features of HSRs influence user satisfaction with the services delivered by HSRs. To address this, a research model was proposed to evaluate how three distinct anthropomorphic features: appearance, voice and response, impact the perceived values (i.e. utilitarian, social and hedonic values) of HSRs, which, in turn, influence user satisfaction.
Design/methodology/approach
Data from an online survey of hotel customers was utilized to test the research model (N = 509).
Findings
The results indicated that appearance, voice, and response affect perceived utilitarian, hedonic and social values differently. The response feature of HSRs demonstrated the strongest impact on perceived utilitarian, social and hedonic values. In addition, voice affected all three perceived values, while appearance only affected perceived utilitarian and social values. Furthermore, perceived utilitarian, hedonic and social values showed positive impacts on user satisfaction, with hedonic value being the most influential factor.
Originality/value
This study contributes to the literature on HSRs and anthropomorphism by explaining how different anthropomorphic features affect users’ value perceptions and user satisfaction with HSR services by utilizing the stimulus-organism-response (SOR) framework.
Details
Keywords
Xiaohui Dou, Yadong Li, Xinwei Zhang, Shengnan Wang, Yang Cheng, Wanpeng Yao, Dalei Zhang and Yan Li
The purpose of this study is to characterize the galvanic corrosion behavior of a simulated X80 pipeline steel welded joint (PSWJ) reconstructed by the wire beam electrode (WBE…
Abstract
Purpose
The purpose of this study is to characterize the galvanic corrosion behavior of a simulated X80 pipeline steel welded joint (PSWJ) reconstructed by the wire beam electrode (WBE) and numerical simulation methods.
Design/methodology/approach
The galvanic corrosion of an X80 PSWJ was studied using WBE and numerical simulation methods. The microstructures of the coarse-grained heat affected zone, fine-grained heat affected zone and intercritical heat affected zone were simulated in X80 pipeline steel via Gleeble thermomechanical simulation processing.
Findings
Comparing the corrosion current density of coupled and isolated weld metal (WM), base metal (BM) and heat-affected zone (HAZ), the coupled WM exhibited a higher corrosion current density than isolated WM; the coupled BM and HAZ exhibited lower corrosion current densities than isolated BM and HAZ. The results exhibited that the maximum anodic galvanic current fitted the Gumbel distribution. Moreover, the numerical simulation results agreed well with the experimental data.
Originality/value
This study provides insight into corrosion evaluation of heterogeneous welded joints by a combination of experiment and simulation. The method of reconstruction of the welded joint has been proven to be a feasible approach for studying the corrosion behavior of the X80 PSWJ with high spatial resolution.
Details
Keywords
Kai Feng, Shengnan Wang, Lina He and Yongxin Li
This study investigated the impact of leader-member exchange (LMX) on emotional exhaustion among Chinese registered construction engineers by examining the mediating role of…
Abstract
Purpose
This study investigated the impact of leader-member exchange (LMX) on emotional exhaustion among Chinese registered construction engineers by examining the mediating role of active management by exception (AMbE) and the moderating role of self-esteem.
Design/methodology/approach
Using a sample of 304 registered construction engineers, the study applies the job demands-resources (JD-R) model to explore how LMX, AMbE and self-esteem interact to influence emotional exhaustion.
Findings
The findings indicate a significant negative relationship between LMX and emotional exhaustion, suggesting that higher-quality exchanges between leaders and members reduce emotional exhaustion. Additionally, AMbE was found to mediate this relationship, where high-quality LMX relationships decrease the extent of AMbE, subsequently lowering emotional exhaustion. Self-esteem was also found to moderate the relationship between AMbE and emotional exhaustion, with high self-esteem exacerbating the negative impact of AMbE and low self-esteem buffering this impact.
Originality/value
These results extend the JD-R model by incorporating leadership quality and management style as critical factors influencing emotional well-being. The study underscores the need for balanced management approaches that consider both supportive and corrective behaviors and highlights the importance of tailoring interventions based on individual differences in self-esteem. The findings provide valuable insights for both theory and practice in managing stress and enhancing the well-being of professionals in high-stress industries. Future research should aim to replicate these findings with larger samples to further validate and extend the results.
Details
Keywords
Qing Jiang, Yuhang Wan, Xiaoqian Li, Xueru Qu, Shengnan Ouyang, Yi Qin, Zhenyu Zhu, Yushu Wang, Hualing He and Zhicai Yu
This study aims to evaluate the thermal performance of sodium alginate (SA) aerogel attached to nano SiO2 and its radiative cooling effect on firefighting clothing without…
Abstract
Purpose
This study aims to evaluate the thermal performance of sodium alginate (SA) aerogel attached to nano SiO2 and its radiative cooling effect on firefighting clothing without environmental pollution.
Design/methodology/approach
SA/SiO2 aerogel with refractory heat insulation and enhanced radiative cooling performance was fabricated by freeze-drying method, which can be used in firefighting clothing. The microstructure, chemical composition, thermal stability, and thermal emissivity were analyzed using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analyzer and infrared emissivity measurement instrument. The radiative cooling effect of aerogel was studied using thermal infrared imager and thermocouple.
Findings
When the addition of SiO2 is 25% of SA, the prepared aerogel has excellent heat insulation and a high radiative cooling effect. Under a clear sky, the temperature of SA/SiO2 aerogel is 9.4°C lower than that of pure SA aerogel and 22.1°C lower than that of the simulated environment. In addition, aerogel has more exceptional heat insulation effect than other common fabrics in the heat insulation performance test.
Research limitations/implications
SA/SiO2 aerogel has passive radiative cooling function, which can efficaciously economize global energy, and it is paramount to environment-friendly cooling.
Practical implications
This method could pave the way for high-performance cooling materials designed for firefighting clothing to keep maintain the wearing comfort of firefighters.
Originality/value
SA/SiO2 aerogel used in firefighting clothing can release heat to the low-temperature outer space in the form of thermal radiation to achieve its own cooling purpose, without additional energy supply.
Graphical abstract
Details
Keywords
Shengnan Liu, Philip Hallinger and Daming Feng
In this era of global education reform, teacher professional learning (TPL) has emerged as a key factor in efforts to create sustainable school improvement. The same holds in…
Abstract
Purpose
In this era of global education reform, teacher professional learning (TPL) has emerged as a key factor in efforts to create sustainable school improvement. The same holds in Mainland China where ambitious curriculum reforms have been undertaken since 2000. The purpose of this paper is to examine the role of learning-centered leadership (LCL) and teacher trust (TT) in fostering TPL in Chinese schools. More specifically, the authors examined two research questions: (1) What is the nature of the relationship of LCL to TT and professional learning?; and (2) How LCL practices influence TT and professional learning.
Design/methodology/approach
The study employed a cross-sectional survey design. The authors collected survey data from 1,259 teachers in 41 primary and secondary schools in three different Chinese provinces. The research employed confirmatory factor analysis to confirm the measurement model and structural equation modeling to examine interactions among the three main variables.
Findings
The results affirmed a positive association between LCL and TPL, and highlighted TT as a significant mediator in this relationship. Additional analyses distinguished between the effects of different dimensions of LCL on TT and TPL. Although the results of these analyses were broadly consistent with prior findings reported in the literature, divergent findings also emerged. More specifically, there was a limited use and no significant impact of “leadership modeling” on either TT or professional learning.
Research limitations/implications
The authors suggest that this pattern of leadership practice is linked with features of China’s institutional cum socio-cultural context. The authors recommend the use of qualitative and mixed methods studies capable of gaining further insight into relationships.
Practical implications
These findings in Mainland China reaffirm the efficacy of school-level leadership that builds a safe, trusting but focussed environment for teacher learning in the workplace. This is a potentially significant finding in a society where the use of top-down directives and reliance on legitimate authority by leaders can rob teachers of the motivation and initiative that undergirds sustainable professional learning. The findings, in concert with those of other scholars, suggest that “building trust” represents a useful strategy for principals who seek to establish productive learning environments for their teachers.
Originality/value
The value of this study lies in two areas. First, this is one of a growing but still limited set of quantitative empirical studies of school leadership in Mainland China. Second, the study tests the nature of mediation in the relationship between leadership, trust and TPL, a topic of relatively recent vintage in the educational leadership literature.
Details
Keywords
Shengnan Han, Shahrokh Nikou and Workneh Yilma Ayele
To improve the academic integrity of online examinations, digital proctoring systems have recently been implemented in higher education institutions (HEIs). The paper aims to…
Abstract
Purpose
To improve the academic integrity of online examinations, digital proctoring systems have recently been implemented in higher education institutions (HEIs). The paper aims to understand how digital proctoring has been practised in higher education (HE) and proposes future research directions for studying digital proctoring in HE.
Design/methodology/approach
A systematic literature review was conducted. The PRISMA procedure was adapted for the literature search. The topics were identified by topic modelling techniques from 154 relevant publications in seven databases.
Findings
Seven widely discussed topics in literature were identified, including solutions for detecting cheating and student authentication, challenges/issues of uptakes and students' performance in different proctoring environments.
Research limitations/implications
This paper provides insights for academics, policymakers, practitioners and students to understand the implementation of digital proctoring in academia, its adoption by HEIs, impacts on students' and educators' performance and the rapid increase in its use for digital exams in HEIs, with particular emphasis on the impacts of the systems on digitalising examinations in HE.
Originality/value
This review paper has systematically and critically described the state-of-the-art literature on digital proctoring in HE and provides useful insights and implications for future research on digital proctoring, and how academic integrity in online examinations can be enhanced, along with digitalising HE.