Search results

The lubricating fluid stored in the porous matrix will spontaneously exude to supplement the lubricating film in the damaged area, thus ensuring the long-term self-lubricating function of the porous surface. To reveal the repair mechanism of oil film, it is necessary to understand the flow characteristics of oil in micropores. The purpose of this study guides the design of micropore structure to realize the rapid exudation of oil to the porous surface and the rapid repair of the lubricating film.

In this paper, cylindrical orifice, convergent orifice and divergent orifice were studied. The numerical model of lubricating oil exudation in micropores was established. The distribution characteristics of oil pressure, velocity and three-phase contact line in the process of oil exudation were investigated. The effects of different orifice shapes and orifice structure parameters on the pinning and spreading characteristics of oil droplet were analyzed. Then the internal mechanisms of oil droplet formation and spread on the orifice surface were summarized.

The results show that during the process of oil exudation, the three-phase contact line of the oil drop is pinned once at the edge of the cylindrical and convergent orifice. Compared with the three orifice structures, the inlet pressure of the oil drop is low, and the oil velocity at the pinning point is stable in the divergent orifice. Resulting in favorable oil exudation. It is easier for oil droplet to depin by appropriately reducing the wall wetting angle, increasing the aperture or controlling the wall inclination angle. Ensure the self-healing and long-lasting lubrication film of porous oil-bearing surfaces.

The effect of pore structure on the flow behavior of lubricating fluid has always been concerned. But the mechanism by which different orifice shape affect the pinning behavior of oil droplets is not yet clear, which is crucial for understanding the self-healing mechanism of oil films on porous surfaces. It is meaningful to analyze the mechanism of oil exudation and spreading on the porous surface of oil in the special orifice, to optimize the design of the orifice structure.

Orifice shape has influence on internal flow field parameters. There is no report on the influence of orifice shape on the film formation process of oil seepage and diffusion from pores. The effects of different orifice shapes and orifice structure parameters on the characteristics of oil droplet pinning and diffusion were studied.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0118/

Flow induced by rotating disks is of great practical importance in several engineering applications such as rotating heat exchangers, turbine disks, pumps and many more. The present research has been freshly displayed regarding the implementation of an engine oil-based Casson tri-hybrid nanofluid across a rotating disk in mass and heat transferal developments. The purpose of this study is to contemplate the attributes of the flowing tri-hybrid nanofluid by incorporating porosity effects and magnetization and velocity slip effects, viscous dissipation, radiating flux, temperature slip, chemical reaction and activation energy.

The articulated fluid flow is described by a set of partial differential equations which are converted into one set of higher-order ordinary differential equations (ODEs) by using convenient conversions. The numerical solution of this transformed set of ODEs has been spearheaded by using the effectual bvp4c scheme.

The acquired results show that the heat transmission rate for the Casson tri-hybrid nanofluid is intensified by, respectively, 9.54% and 11.93% when compared to the Casson hybrid nanofluid and Casson nanofluid. Also, the mass transmission rate for the Casson tri-hybrid nanofluid is augmented by 1.09% and 2.14%, respectively, when compared to the Casson hybrid nanofluid and Casson nanofluid.

The current investigation presents an educative response on how the flow profiles vary with changes in the inevitable flow parameters. As per authors’ knowledge, no such scrutinization has been carried out previously; therefore, our results are novel and unique.

The study tests risk-taking and risk-aversion capabilities while distinguishing between business group firms and stand-alone firms and considering oil price volatility. Second, this attempt to study the linkage between risk-taking during market down movements and when the firms have established themselves as product market leaders. Third, this study analyses the “sentiment” state, where it explores the reaction of corporations when the market is in the negative direction, and lastly, it explores the linkage between product market competition and risk-aversion.

This study uses financial information for 1,273 non-financial companies and other required data from various sources. The study employs panel data and utilizes different empirical methodologies, including the generalized method of moments (GMM) estimator, to test the stated hypotheses.

We find that the business group firms have more risk-taking proficiencies compared with the stand-alone firms. Moreover, this study discovers that the corporates avoid taking risks when the market is not performing well. Also, when the market is down and crude prices are high, the management expects high earnings in the future, willingly takes risks and shows that product market leaders do not follow the risk-aversion strategy.

The empirical results indicate that oil price movement can restrict management’s behaviour when choosing a risky investment project. Management should develop a robust policy that follows the group of firms. In the policy, the management should describe the level of risk that may be taken by the firm and implement it when required.

Since we do not find any studies in this context, then there is a major and essential gap in the literature that this study should fill.

This paper aims to reveal the influence of the grooved texture parameters on the lubrication performance of circular pocket-roller pairs in cylindrical roller bearings.

In this paper, the thermal elastohydrodynamic lubrication mathematical model of the grooved texture circular pocket-roller pair was established, the finite difference method and successive over-relaxation method were used to solve the model, the influence of texture quantity, texture depth and texture area ratio on circumferential bearing capacity, friction coefficient, maximum temperature rise, stiffness and damping of the circular pocket-roller pairs were analyzed.

The results show that texture quantity, texture depth and texture area ratio significantly influence the static and dynamic characteristics of circular pocket-roller pairs. The suitable surface groove texture parameters can dramatically improve the circumferential bearing capacity, reduce the friction coefficient, inhibit the maximum temperature rise and increase the stiffness and damping of the circular pocket-roller pairs.

The research in this paper can provide a theoretical basis for the optimization design of pockets in cylindrical roller bearings to reduce friction and vibration.

Industrial drivetrains use wet disk clutches for safe and reliable shifting. Advances over the past decades regarding the formulation of lubricants and the composition of friction materials have led to reliable clutch systems. In this context, the friction behavior is crucial for the correct operation of the clutch. Nevertheless, the friction behavior and its influencing factors are still the object of modern research. The purpose of this study is to investigate how the choice of the steel disk influences the noise vibration and harshness (NVH) behavior of wet industrial clutches.

To investigate the influence of the steel disk on the friction and NVH behavior of industrial wet disk clutches, experimental investigations with relevant friction systems are conducted. These tests are performed at two optimized test rigs, guaranteeing transferable insights. The surface topography of the steel disk and the friction lining are measured for one friction system to identify possible relations between the surface topography and the friction behavior.

The steel disk can influence the friction behavior of wet disk clutches. Using a different steel disk surface finish, corresponding results can show differences in the shudder tendency, leading to a nonfavorable NVH behavior – different gradients of the coefficient of friction over sliding velocity cause this phenomenon.

This work gives novel insights into the friction and NVH behavior of industrial wet disk clutches. It supports engineers in the optimization of modern friction systems.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2024-0054/

This paper aims to examine the effects of oil price uncertainty on corporate investment of Islamic stocks during the COVID-19 pandemic.

The study uses a panel data set that covers 398 listed Islamic stocks from seven major Asia Pacific countries over the period of five years from 2017 to 2021, yielding 1,990 observations. Specifically, this paper investigates the said association by combining the real options theory regarding investment and the panel data-based econometric method that captures the dynamic relationship, the generalized method of moments estimators.

The findings show that the relationship between the oil price volatility and corporate investment of Islamic stocks is significant and nonlinear in nature, suggesting the presence of both the growth options and the waiting options. Overall, the results reveal that corporate investment of Islamic stocks is hindered during the unprecedented corona crash, when oil price increases at exponential rates.

The findings suggest that considering the information caused by unprecedented events like the COVID-19 pandemic is crucial for investment decisions of Islamic stocks. Therefore, policymakers and regulators should incorporate the impact of oil price uncertainties caused by unprecedented events like the COVID-19 pandemic on firm’s investment expansion and diversification strategies.

To the best of the authors’ knowledge, this paper is the first to examine the relationship between the investment of Islamic stocks and the oil price uncertainty under compound options theory in top Asian oil-importing countries.

This study aims to enhance heat transfer efficiency while minimizing friction factor and entropy generation in the flow of Nickel zinc ferrite (NiZnFe₂O₄) nanoparticles suspended in multigrade 20W-40 motor oil (as specified by the Society of Automotive Engineers). The investigation focuses on the effects of the melting process, nonspherical particle shapes, thermal dispersion and viscous dissipation on the nanofluid flow.

The fundamental governing equations are transformed into a set of similarity equations using Lie group transformations. The resulting set of equations is numerically solved using the spectral local linearization method. Additionally, sensitivity analysis using response surface methodology (RSM) is conducted to evaluate the influence of key parameters on response function.

Higher dispersion reduces entropy production. Needle-shaped particles significantly enhance heat transfer by 27.65% with melting and reduce entropy generation by 45.32%. Increasing the Darcy number results in a reduction of friction by 16.06%, lower entropy by 31.72% and an increase in heat transfer by 17.26%. The Nusselt number is highly sensitive to thermal dispersion across melting and varying volume fraction parameters.

This study addresses a significant research gap by exploring the combined effects of melting, particle shapes and thermal dispersion on nanofluid flow, which has not been thoroughly investigated before. The focus on practical applications such as fuel cells, material processing, biomedicine and various cooling systems underscores its relevance to sectors such as nuclear reactors, tumor treatments and manufacturing. The incorporation of RSM for friction factor analysis introduces a unique dimension to the research, offering novel insights into optimizing nanofluid performance under diverse conditions.

This paper aims to provide a more comprehensive look behind the China’s rapid ascent and influence across the African continent by exploring the Sino-African funding data at the project level while incorporating recipient nations’ economic characteristics of interest such as trade data and natural resources endowment.

Combining AidData’s project reported data with country bilateral exports and imports data and other pertinent African countries’ data, the authors are able to perform a cross-sectional interrogation of China’s finding motives and their impact on the continent. The results indicate that the China’s funding to Africa mostly goes to energy and transportation sectors, as expected, and the recipient country’s exports to China increase as the funding increases. However, the authors find that the impact of China’s financing on the bilateral trade flow is unbalanced because the recipient country’s imports from China are not found to be significant.

Interestingly, although the analysis confirms that oil is a key contributing factor in attracting China’s funding, the authors discover that there exists no positive relationship between the China funding amount and the recipient country’s general natural resource level. The results do not support the common notion that China is primarily interested in extracting natural resource deposits, aside from oil, from the host nation when they allocate their funding.

Overall, the paper supports the theoretical propositions of the new structural economics framework when it comes to the relationship between China’s funding and the recipient country’s characteristics.

The purposes of this paper are optimization of high speed reducer in electric vehicles based on the analysis of lubrication and verification of simulation accuracy and optimization results.

The traditional CFD method presents poor applicability to complex geometric problems due to grid deformity. Therefore, moving particle semi-implicit (MPS) method is applied in this study to simulate lubrication of the reducer and analyze the influence of input speed and lubrication system design on the distribution. According to the results, the reducer is optimized. Meanwhile, the experiments for lubrication and churning power loss is carried out to verify the accuracy of simulation and optimization effects.

The flow field of lubricant inside the reducer is obtained. The lubrication system of reducer needs to be improved. Simulation and experiment show that the optimization is sufficient and efficient.

According to the simulation of lubrication, the reducer is optimized. The lubrication experimental setup is established. The conclusion of paper can provide the method and tool for reducer in electric vehicle.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0123/

This study investigates the impact of oil price uncertainty on corporate cash holdings. Moreover, it examines whether the effect of oil price volatility differs between Shariah-compliant corporations (SCCs) and non-Shariah-compliant corporations (NSCs). It also explores the role of Islamic financial development in the home countries of these corporations in this relationship

The study utilizes a sample of non-financial firms listed in eight emerging economies, for the period between 2013 and 2019. A static, ordinary least squares, and dynamic, Generalized Method of Moments models have been employed to test the hypotheses of the study.

The findings reveal that, on average, high oil price uncertainty influences both SCCs and NSCs. However, SCCs are more severely affected than NSCs. Notably, during periods of high oil price uncertainty, SCCs reserve more cash than their NSC counterparts. Additionally, the Islamic financial development of the country moderates the severity of the impact of oil price uncertainty on SCCs. Further analysis suggests that the impact of oil price uncertainty is more pronounced for firms operating in oil-exporting countries.

Corporate managers should build a liquidity strategy that allows them to deal with oil price uncertainty. Also, the findings of the study highlight the importance for Islamic financial development of Islamic countries. The improved Islamic financial development of the country improves access to capital markets for shariah compliant firms and hence, reduces their need for holding excessive large amount of cash asset.

The study contributes to the growing literature on the effects of oil price uncertainty on corporate cash holding policy by highlighting the roles of Shariah compliance status and Islamic financial development in this relationship. It is the first to explore the joint relationship between oil price uncertainty, Shariah compliance, and corporate cash holding policy.