Yanfei Yang, Xiaobo Wang, Sen Mei, Xing Zhu, Shiqiang Chen, Peng Xiong, Zhihai Hu, Kun Xiong and Dong Song Yuan
The purpose of this paper is to investigate the tribological performance and mechanisms of BN/calcium borate nanocomposites (BCBNs) as additives in lubricating oil.
Abstract
Purpose
The purpose of this paper is to investigate the tribological performance and mechanisms of BN/calcium borate nanocomposites (BCBNs) as additives in lubricating oil.
Design/methodology/approach
BCBNs were prepared by heterogeneous deposition method. And the morphology and structure of samples were analysed by transmission electron microscopy, Fourier transform infrared spectra and X-ray powder diffraction pattern. The maximum non-seizure load (PB) of samples was tested using four-ball friction tester. The average friction coefficients and wear tracks were obtained. In addition, tribological mechanism was also investigated using optical microscope, energy dispersive spectroscopy and X-ray photoelectron spectroscope.
Findings
It was found that the nanocomposites present core-shell nanostructure with the thickness of shell around 12 nm and the diameter of particles 100-200 nm, and tribological tests indicate that the PB value of BCBNs was increased by 113 per cent, whereas the average friction coefficient was decreased by 23.6 per cent and the bloom’s wear area was also decreased by 25.2 per cent.
Originality/value
This paper involves investigation on tribological properties and mechanism of the BCBNs with core-shell structure.
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Rakesh Belwal and Shweta Belwal
The purpose of this paper is to explore the factors affecting store image and customers’ choice of hypermarkets in Oman and compares two big hypermarkets in Sohar– the prominent…
Abstract
Purpose
The purpose of this paper is to explore the factors affecting store image and customers’ choice of hypermarkets in Oman and compares two big hypermarkets in Sohar– the prominent industrial city of Oman.
Design/methodology/approach
A detailed review of literature was conducted initially to identify the attributes affecting store image and choice of hypermarkets in Oman and a questionnaire was developed later using the key attributes, vetted by a panel of professionals and consumers. Data were collected using convenience sampling from the targeted customers with due care to reduce possible biases. Exploratory factor analysis (EFA), using SPSS, was then performed to arrive at the key factors affecting store image and choice of hypermarkets in Oman. Two most popular and leading hypermarkets of Sohar – Lulu and Al Safeer were selected to study consumers’ preferences for store choice and comparisons. The Mann-Whitney U-test in association with the Wilcoxon W-test was applied, using Minitab, for further comparison of the two hypermarkets.
Findings
Retailing industry in Oman is changing. The focus of consumers is shifting from traditional markets to modern retail formats. The presence of hypermarkets has attracted customers away from traditional souqs. Customers are attracted to hypermarkets for various reasons, including the local and socio-cultural ones. The factor analysis produced four components, namely, “purchase experience”, “visit experience”, “augmented experience”, and “repeat-purchase experience” affecting customers’ choice of hypermarkets and store image in Oman. A comparative analysis of two leading hypermarkets revealed that Lulu hypermarket acquired, overall, a better store image over Al Safeer on all the components. Purchase experience and visit experience, in Omani hypermarkets, were forerunners in satisfying customers than the augmented and repeat-purchase experience.
Research limitations/implications
The study contributes to the narrow base of extant literature on consumer preferences of hypermarkets and their choice of related retail formats in the Islamic world. Although the use of EFA has been quite informative in revealing the findings, the limitation mainly arises due to the lack of confirmatory techniques, which were not intended at this stage of research. Whist the study opens room for researchers to contribute further in this regard, it brings forth certain implications for the managers, academics, and professionals working in the retail sector.
Practical implications
Analysis and discussions reveal that hypermarkets, particularly in Oman, need to take into account the factors, as identified in this study, and the differences in context of local conditions and religion. The study emphasizes that managers of retail formats in Oman need to give due importance to consumer experience to secure better store image and consumer patronage.
Originality/value
The study makes a pioneering attempt to analyse consumer preferences for retail stores, especially hypermarkets in Oman. It recognizes that the consumer expectations and business requirements of Oman, in particular, or Gulf countries in general are somehow different than the rest of the world. A heed to the identified factors and underlying variables would help the retail sector in serving consumers better as well as in increasing the store image and consumer patronage.
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Yanhong Yan, Chengwen Yang, Yanfei Zhou, Wenbin Dong, Pengjuan Yan and Zhining Jia
Previously, the effect of pore-forming agents on the properties of pore size and morphology was studied. In this paper, we determine the optimal combination of parameters by…
Abstract
Purpose
Previously, the effect of pore-forming agents on the properties of pore size and morphology was studied. In this paper, we determine the optimal combination of parameters by tensile strength and perform tribological tests with optimal combination of parameters.
Design/methodology/approach
In this paper, porous polyimide (PI) materials were fabricated using vacuum hot molding technology. The orthogonal experiment was designed to test the mechanical properties of porous PI materials with the process parameters and the content of pore-forming agent as the changing factors. The porous PI oil-bearing materials were obtained by vacuum immersion, and tribological test were carried out.
Findings
The results showed that porous PI oil-bearing materials are suitable for low-speed and low-load conditions. The actual value of the friction coefficient basically match with the theoretical value of the regression analysis, and the errors of the friction coefficient are within 10% and 3%, respectively, which proves that the method used in the study is feasible for the friction coefficient prediction.
Originality/value
In this paper, we have produced a new porous oil-bearing material with good tribological properties. This study can effectively predict the friction coefficient of PI porous material.
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Yanhong Yan, Xiaocui Yan, Chengwen Yang, Yanfei Zhou, Zhining Jia and Caizhe Hao
The purpose of this study is to improve the dispersion of nanoserpentine modified with OA, KH550 and KH550/oleic acid in lubricating oil. The main aims are to analyze the…
Abstract
Purpose
The purpose of this study is to improve the dispersion of nanoserpentine modified with OA, KH550 and KH550/oleic acid in lubricating oil. The main aims are to analyze the influence of the dispersion and stability of nanoserpentine modified by different modifiers on the friction properties of lubricating oil.
Design/methodology/approach
The nanoserpentine particles obtained by ball-milling were modified by silane coupling agent KH550, OA and KH550/OA, respectively. The dispersity and stability of nanoserpentine in base lubricating oil were characterized by the absorbance value method, centrifuge precipitation rate method and static observation method. The MMU-5G screen display friction and wear tester was used to evaluate the tribological properties of C45E4/C45E4 friction pairs in corresponding lubricating oils. The surface morphology of the friction pairs was observed by scanning electron microscopy and energy dispersive spectroscopy.
Findings
The results showed that the dispersity and stability of nanoserpentine particles in lubricating oil were best modified by OA, followed by the KH550/OA and finally, the KH550. Nanoserpentine particles modified with oleic acid showed optimum tribological properties as lubricant additives.
Originality/value
This study can improve the dispersion stability of nanoserpentine particles in lubricating oil, increasing the antiwear and antifriction performance of lubricating oil, which has great significance in economic and military aspects.
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Yanfei Lu, Futian Weng and Hongli Sun
This paper aims to introduce a novel algorithm to solve initial/boundary value problems of high-order ordinary differential equations (ODEs) and high-order system of ordinary…
Abstract
Purpose
This paper aims to introduce a novel algorithm to solve initial/boundary value problems of high-order ordinary differential equations (ODEs) and high-order system of ordinary differential equations (SODEs).
Design/methodology/approach
The proposed method is based on Hermite polynomials and extreme learning machine (ELM) algorithm. The Hermite polynomials are chosen as basis function of hidden neurons. The approximate solution and its derivatives are expressed by utilizing Hermite network. The model function is designed to automatically meet the initial or boundary conditions. The network parameters are obtained by solving a system of linear equations using the ELM algorithm.
Findings
To demonstrate the effectiveness of the proposed method, a variety of differential equations are selected and their numerical solutions are obtained by utilizing the Hermite extreme learning machine (H-ELM) algorithm. Experiments on the common and random data sets indicate that the H-ELM model achieves much higher accuracy, lower complexity but stronger generalization ability than existed methods. The proposed H-ELM algorithm could be a good tool to solve higher order linear ODEs and higher order linear SODEs.
Originality/value
The H-ELM algorithm is developed for solving higher order linear ODEs and higher order linear SODEs; this method has higher numerical accuracy and stronger superiority compared with other existing methods.
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Taegoo Terry Kim, Gyehee Lee, Soyon Paek and Seunggil Lee
The purpose of this paper is to investigate an integrative model that explores the influence of knowledge-sharing enablers (social capital (SC), including structural, relational…
Abstract
Purpose
The purpose of this paper is to investigate an integrative model that explores the influence of knowledge-sharing enablers (social capital (SC), including structural, relational, and cognitive SC) on knowledge-sharing (KS) processes (KS behaviors: knowledge collecting (KC) and knowledge donating (KD)) as well as a further superior KS outcome (organizational performance).
Design/methodology/approach
The survey was administered in 14 top tier five-star hotels in Seoul, Korea. Employees of the hotels participated in the survey; 486 surveys were used to investigate a research model and hypotheses using a path analysis.
Findings
The research confirmed the importance of SC in the context of KS from the resource-based view. The paper provides empirical evidence that structural, relational, and cognitive SC affected KC and KD, which in turn influenced organizational performance. Interestingly, whereas cognitive SC has the strongest effect on employees' KC, relational SC has the strongest effect on employees' KD. The impact of employees' KC on organizational performance appears to be stronger than that of KD.
Practical implications
The relationships among KS enablers, processes, and organizational performance may provide a clue regarding how hotels can promote KS culture, which focuses on the social dynamics derived from interpersonal and group relationships to boost their performance by increasing employees' willingness to collect knowledge from and donate knowledge to colleagues.
Originality/value
This study explores the under-researched subject of SC with regard to KS and their roles in promoting organizational performance within a hospitality industry context. The study is among the first to examine SC as an organizational resource, two distinctive types of KS behaviors as an organizational capability, and organizational performance from both an integrative (KS enablers-processes-outcomes framework) and resource-based view of the firm's perspective simultaneously. Especially, this study identifies the specific mechanism of two distinctive types of employees' KS behaviors, such as KC and KD, between SC factors and organizational performance.
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Yu Zhu, Wenjuan Mei, Meilan Nong and Yanfei Wang
Existing research has generally viewed that temporal leadership has positive impacts on employees but ignores its potential drawbacks. This study aims to develop a model to…
Abstract
Purpose
Existing research has generally viewed that temporal leadership has positive impacts on employees but ignores its potential drawbacks. This study aims to develop a model to explore its possible negative impacts on employees, drawing upon social information processing theory.
Design/methodology/approach
This study conducts a multi-wave and multisource survey to test the model, and the authors test the hypotheses with multi-level analysis using Mplus 7.4 and R package for Monte Carlo.
Findings
Results suggest that temporal leadership induces employee work alienation, thus leading to employee silence. Furthermore, shared temporal cognitions moderate both the relationship between temporal leadership and work alienation and the indirect effect of temporal leadership on employee silence via work alienation.
Originality/value
Taken together, this study reveals the potential dark side of temporal leadership and provides a more comprehensive and dialectical research perspective for temporal leadership literature.
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Serhat Yüksel and Gözde Gülseven Ubay
No carbon gas is released into the atmosphere in electricity production with wind energy. Therefore, this type of energy is significantly environmentally friendly. On the other…
Abstract
No carbon gas is released into the atmosphere in electricity production with wind energy. Therefore, this type of energy is significantly environmentally friendly. On the other hand, thanks to wind energy investments, a country can produce its own energy. This reduces the country’s foreign dependency on energy. Due to these positive aspects, increasing wind energy investments is very important for both the social and economic development of the country. The aim of this study is to define the most appropriate government support to improve wind energy investments. In this context, four different criteria are defined in this regard by making a detailed literature review. In the analysis process, fuzzy AHP methodology is considered. Within this framework, the comparative evaluations of three different experts are obtained. The findings indicate that providing loans with low-interest rate is the most appropriate government support for the wind energy investors. Additionally, it is also defined that tax deduction is another important issue for this purpose. However, it is also identified that appropriate location supply and purchase guarantee of the product produced have lower importance in comparison with the others. It is strongly recommended that governments should provide loans to the wind energy investors. This strategy can minimize the problem of high initial cost so that it can be much easier to attract the attention of the investors.
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Juan Tan, Yanfei Wang, Mouwu Liu and Jing Liu
The purpose of this paper is to study the tribological properties of a thiazole derivatives (T561), overbased alkyl benzene calcium sulfonate (T106A) compounded with T561 and…
Abstract
Purpose
The purpose of this paper is to study the tribological properties of a thiazole derivatives (T561), overbased alkyl benzene calcium sulfonate (T106A) compounded with T561 and overbased alkyl benzene magnesium sulfonate (T107) compounded with T561 in rapeseed oil (RSO).
Design/methodology/approach
A four-ball machine was used to evaluate the tribological properties of each compound and their combinations with T561 in RSO. Scanning electron microscopy, EDX and X-ray photoelectron spectroscopy were applied to analyze the tribofilm formed on the worn surfaces.
Findings
Results of tribotesting demonstrated that synergistic effects exist between the overbased sulfonates, T106A and T107, and the thiazole derivative, T561. The texts of tribofilm indicated that iron sulfide and iron oxides exist in T561 single agent lubricant film and two composite additives lubricant film, and no sulfates were detected. It suggested that the addition of alkyl benzene sulfonate did not hinder the formation of iron sulfides and iron oxides. Meanwhile, CaSO4 (MgSO4) and CaCO3 (MgCO3) were detected on the worn surface of the composite additives, which were not detected on the single agent friction surface.
Originality/value
A tribofilm mainly contains CaSO4 (MgSO4) and CaCO3 (MgCO3) formed on the worn surfaces, which is responsible for excellent extreme pressure and anti-wear properties of the compound agents because of their high melting point and high shear stress.
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Xueping Hu, Pengfei Tang, Yanfei Wang and Jing Liu
Water-based graphite lubricants have good lubricity in the process of metal forming, especially for hot-rolling seamless pipe. Although the use of water as a working fluid system…
Abstract
Purpose
Water-based graphite lubricants have good lubricity in the process of metal forming, especially for hot-rolling seamless pipe. Although the use of water as a working fluid system instead of conventional mineral oil has many advantages for the fuel consumption, post cleaning and a new type of lubricant, the graphite contaminated the machine and workers for its physical properties. From the global environmental protection viewpoint, it is urgent to develop a kind of benign material.
Design/methodology/approach
Magnesium hydroxide which has the average particle size of 10 μm was chosen as a base material without further modification and pretreatments. On the HT-1000 high-temperature tribometer, the influence of temperature and lubricant materials on the friction coefficient was studied. The tribological performance at 900°C provided evidence under high temperature for exploring a new lubricant material.
Findings
Tap water-based brucite lubricant will open a new chapter in the industrial lubrication, effectively avoiding many unfavorable factors caused by graphite lubrication, such as conductivity, pollution and energy loss. Meanwhile, it expanded the application of brucite as flame-retardant agent, catalyst, water treatment agent and so on.
Originality/value
It is a new and environmental lubricant to tap water-based brucite lubricant. And specially, the preparation process of lubricant is simple and economical.