This study aims to investigate the cross-sectional reshaping in transitioning/starting rectangular jets of aspect ratio 2 under various inlet perturbation conditions at the…
Abstract
Purpose
This study aims to investigate the cross-sectional reshaping in transitioning/starting rectangular jets of aspect ratio 2 under various inlet perturbation conditions at the Reynolds number of Re = UDh/v = 17,750.
Design/methodology/approach
Large eddy simulation results compared with the phase-locked particle image velocimetry data exhibit the cross-sectional jet deformations from rectangular to rounder shapes. Inflow velocity oscillations are introduced at the fundamental frequency associated with the Kelvin–Helmholtz instability characterized by the spectral analysis of the hotwire data and the linear stability predictions.
Findings
The initially rectangular cross-section of the jet reshapes into the rounder geometries with increased downstream distance while the edges of the jet become distorted due to the shear layer instability more significantly observed near the high curvature corners. The different expansion rates in the longer and shorter edges of the jet and the consequent cross-sectional reshaping are found to be sensitive to small levels of random inlet perturbations. In addition, introducing controlled sinusoidal oscillations results in the formation of more organized trailing shear layer where the stronger vortex rings go through the curvature-induced deformations.
Originality/value
Spatio-temporal study of vortex dynamics in transitioning rectangular jets reveals important information about the effect of the controlled jet forcing on local entrainment. Dynamics of the leading vortex dominates the entrainment in transitioning jets which are commonly used in practical applications. Near-field entrainment is also promoted proportional to the amplitude of the controlled inlet oscillations within the trailing vortex rings.
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Tengxiao Jiao, Xiaohua Zhao and Xianguo Li
This research aims to explore the interactions of stakeholders in online food delivery (OFD) platforms, including restaurants, the delivery system and the platform, and the effect…
Abstract
Purpose
This research aims to explore the interactions of stakeholders in online food delivery (OFD) platforms, including restaurants, the delivery system and the platform, and the effect on total sales. In order to comprehensively analyze the service of stakeholders, the authors adopted the time duration which provides a unified metric for assessing service performance.
Design/methodology/approach
The authors used panel vector autoregressive (PVAR) model analysis to verify the interactions among restaurants, the delivery system, and the platform itself, and to assess their effects on the sales. Data were collected from one of the biggest OFD service platforms in China – Eleme.com.
Findings
First, the findings confirmed that the service performance of restaurants, the delivery system and the platform itself influence one another. There is a bidirectional causality between food preparation time (FPT) and actual delivery time (ACDT), as well as between FPT and advance arrival time (ADAT), ACDT and ADAT. Second, the service performance of restaurants, the delivery system, and the platform itself all positively affect sales, thus demonstrating unidirectional causality.
Originality/value
The current research is a pioneering empirical study, as it confirms the dynamic interactions between participants in OFD platforms and the dynamic influence of their respective service performances on sales. The findings of this research have a number of implications for the management and operation of online food ordering and delivery platforms.
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The purpose of this paper was to map the safety management research of construction industry by scientometric analysis, which can predict important highlights and future research…
Abstract
Purpose
The purpose of this paper was to map the safety management research of construction industry by scientometric analysis, which can predict important highlights and future research directions of safety management research in the construction industry. As an important issue in the construction industry, safety management issues have been researched from different perspectives. Although previous studies make knowledge contributions to the safety management research of construction industry, there are still huge obstacles to distinguish the comprehensive knowledge map of safety management research in the construction industry.
Design/methodology/approach
This study applies three scientometric analysis methods, collaboration network analysis, co-occurrence network analysis and cocitation network analysis, to the safety management research of construction industry. 5,406 articles were retrieved from the core collection database of the Web of Science. CiteSpace was used for constructing a comprehensive analysis framework to analyze and visualize the safety management research of construction industry. According to integrating the analysis results, a knowledge map for the safety management research of construction industry can be constructed.
Findings
The analysis results revealed the academic communities, key research topics and knowledge body of safety management research in the construction industry. The evolution paths of safety management research in the construction industry were divided into three development stages: “construction safety management”, “multi-objective safety management” and “comprehensive safety management”. Five research directions were predicted on the future safety management research of construction industry, including (1) comprehensive assessment indicators system; (2) intelligent safety management; (3) cross-organization collaboration of safety management; (4) multilevel safety behavior perception and (5) comparative analysis of safety climate.
Originality/value
The findings can reveal the overall status of safety management research in the construction industry and represent a high-quality knowledge body of safety management research in the construction industry that accurately reflects the comprehensive knowledge map on the safety management research of construction industry. The findings also predict important highlights and future research directions of safety management research in the construction industry, which will help researchers in the safety management research of construction industry for future collaboration and work.
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Lidan Yao, Lixin Wang, Haining Yang, Chuan Li, Hui Song and Xianguo Hu
This paper aims to investigate the influence of stearate types on the thickening ability, dropping point and fiber structure of greases.
Abstract
Purpose
This paper aims to investigate the influence of stearate types on the thickening ability, dropping point and fiber structure of greases.
Design/methodology/approach
Several greases were prepared from polyolefins and various stearates. The melting point of the stearates and the dropping point of the resultant greases were measured, and the intermolecular binding energies of the thickener and the radial distribution function of the metal–oxygen in the thickener were determined with the aid of molecular simulation. The microstructures of the greases were also analyzed via scanning electron microscopy.
Findings
A higher stearate binding energy was found to correlate to a higher dropping point of the resultant greases. The thickening ability of the stearate is related to the group and period of the constituent metal ion. Within a group, greater atomic numbers of the metal were correlated to lower thickening ability. In a period, as the atomic number of the metal increased, the thickening ability was enhanced. The radial distribution functions of metal and oxygen can explain the aggregation of the stearate thickeners in the grease.
Originality/value
This work compared the thickening capacity of several stearates. Guidelines for preparing stearates to tailor the resultant grease are presented.
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Ziyan Lu, Feng Qiu, Hui Song and Xianguo Hu
This paper aims to solve the problems molybdenum disulfide (MoS2) nanosheets suffer from inadequate dispersion stability and form a weak lubricating film on the friction surface…
Abstract
Purpose
This paper aims to solve the problems molybdenum disulfide (MoS2) nanosheets suffer from inadequate dispersion stability and form a weak lubricating film on the friction surface, which severely limits their application as lubricant additives.
Design/methodology/approach
MoS2/C60 nanocomposites were prepared by synthesizing molybdenum disulfide (MoS2) nanosheets on the surface of hydrochloric acid-activated fullerenes (C60) by in situ hydrothermal method. The composition, structure and morphology of MoS2/C60 nanocomposites were characterized. Through the high-frequency reciprocating tribology test, its potential as a lubricant additive was evaluated.
Findings
MoS2/C60 nanocomposites that were prepared showed good dispersion in dioctyl sebacate (DOS). When 0.5 Wt.% MoS2/C60 was added, the friction reduction performance and wear resistance improved by 54.5% and 62.7%, respectively.
Originality/value
MoS2/C60 composite nanoparticles were prepared by in-situ formation of MoS2 nanosheets on the surface of C60 activated by HCl through hydrothermal method and were used as potential lubricating oil additives.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2023-0321/
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Xianguo Hu, Yourong Wang and Hefeng Jing
The purpose of this paper is to develop a new oil‐in‐water (O/W) emulsion used for alpha phase brass, which can increase the antiwear and anti‐galling abilities of the rollers…
Abstract
Purpose
The purpose of this paper is to develop a new oil‐in‐water (O/W) emulsion used for alpha phase brass, which can increase the antiwear and anti‐galling abilities of the rollers, and improve the surface quality of the rolled brass sheet. The aim is to evaluate the tribological performance of new kind of O/W emulsion for the hot rolling of alpha brass, which provides the fundamental information for the selecting of new chemical group, and to understand the lubrication mechanism of the used rolling emulsion and to correlate the laboratory findings with those of industrial rolling of alpha phase brass.
Design/methodology/approach
According to the hydrophile‐lipophile balance theory and the evaluation results of friction, wear and lubrication using a four‐ball tribometer, a novel O/W emulsion was developed for the hot rolling process of CuZn32(ASTM C26200) and CuZn30(ASTM C26000) alloys by controlling the composition of the emulsion, such as emulsifying, antiwear, extreme pressure, antirust and so on. By scanning electron microscope (SEM), energy‐dispersive X‐ray (EDX), and roughness profile the tribological mechanism were studied.
Findings
The production result proved that it was easy to control the accuracy and size of the brass sheet because of the emulsion‐jet to the roller surface directly and in succession. Polyol with hydroxyl group is found to provide better lubrication and lower coefficient of friction. The actual hot rolling results proved that it was easy to control the accuracy and size of the brass sheet with the emulsion jet. The morphologies and roughness profile of the copper sheet surface were observed and measured by SEM and topographic meter under different lubricant conditions. The in situ results supported the selection of compositions of O/W emulsion. The suitable temperature of feed emulsion is over 20°C.
Research limitations/implications
The tribological mechanism of friction modified emulsion is not still clear. The thermal mechanical properties of rollers under this kind of emulsion are also worth studying in the future.
Practical implications
Understanding the tribological behaviour of O/W emulsion, will be useful for emulsion chemists, tribologists and rolling mill users.
Originality/value
The current study shows new compositions of O/W emulsion used for hot rolling of alpha phase brass.
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Daoyi Wu, Yufu Xu, Lulu Yao, Tao You and Xianguo Hu
This paper aims to study the upgradation of the lubricating performance of the renewable base oil , and to study the tribological behavior of graphene oxide (GO) sheets used as…
Abstract
Purpose
This paper aims to study the upgradation of the lubricating performance of the renewable base oil , and to study the tribological behavior of graphene oxide (GO) sheets used as lubricating additives in bio-oil for iron/steel contact.
Design/methodology/approach
A multifunctional end-face tribometer was used to characterize the friction coefficient and wear loss of the tribosystem under different lubricants.
Findings
The experimental results show that GO sheets with small size benefit lubricating effects and the optimal concentration of GO sheets in bio-oil is 0.4-0.6 per cent, which can form a complete lubricating film on the frictional interfaces and obtain a low friction coefficient and wear loss. Higher concentration of GO sheets can result in a significant aggregation of the sheets, reducing the content of the lubricating components in the bio-oil, which results in the increase in friction and wear; at this stage, the main wear pattern was ascribed to adhesive wear.
Practical implications
These results show a promising prospect of improving the tribological performance of renewable base oil with the introduction of GO sheets as additives.
Originality/value
No literature has covered the tribological behaviour of GO sheets in bio-oil. This study contributes to accelerating the application of bio-oil.
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Kunhong Hu, Yongkui Cai, Xianguo Hu and Yufu Xu
The purpose of this paper is to explore the synergistic lubrication of MoS2 particles with different morphologies.
Abstract
Purpose
The purpose of this paper is to explore the synergistic lubrication of MoS2 particles with different morphologies.
Design/methodology/approach
The synergistic lubrication of MoS2 particles with different morphologies is evaluated using a four‐fall tribometer in liquid paraffin.
Findings
Results show that the morphology of MoS2 has an influence on the tribological properties of MoS2. Both MoS2 nano‐balls and nano‐platelets function as lubrication additives in liquid paraffin better than MoS2 micro‐platelets do. It is also found that there is a synergistic lubrication between two different morphologies of MoS2. The composite MoS2 additives with different morphologies can improve the wear resistance and friction reduction of liquid paraffin more than each of them singly does. The synergistic lubrication between two different MoS2 morphologies results from the cooperation of their different lubrication mechanism.
Originality/value
The paper reveals a synergistic lubrication between two different MoS2 structures. It is very advantageous and practical to partly displace nano‐MoS2 with micro‐MoS2.
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Gina María Maria Pipoli de Azambuja, Iñaki García-Arrizabalaga and Gustavo Rodríguez-Peña
This study aims to examine the relation between the purchase intention of Peruvian maca and each of the following variables: Peru’s country image, maca’s product image, Peru’s…
Abstract
Purpose
This study aims to examine the relation between the purchase intention of Peruvian maca and each of the following variables: Peru’s country image, maca’s product image, Peru’s country familiarity and maca’s product familiarity.
Design/methodology/approach
To compile primary information, a survey of closed questions was applied to students in two countries with different levels of familiarity with Peru: France and the USA.
Findings
There is a direct association between the studied variables in the cases where the foreign consumer has a high familiarity with Peru. Similarly, there is a positive association between maca’s product image, Peru’s country familiarity and maca’s product familiarity with the consumer purchase intention of maca from Peru in the cases where the consumer has low familiarity with Peru.
Research limitations/implications
The characteristics of the sample did not allow to analyze the purchase intention according to gender, age and socioeconomic level.
Practical implications
This study provides innovative insights to design international marketing strategies for Peruvian maca entrepreneurs and export promotion policies to policymakers, to support them to overcome the increase of the global competitive environment of maca.
Social implications
The paper helps maca producers and exporters to develop international marketing strategies to position their maca products in markets with high or low familiarity with Peru.
Originality/value
The uniqueness of this paper is based on the study of the purchase intention of agricultural products such as maca, which is a developing product available in Peru.
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Li Ji, Yiwei Zhang, Ruifeng Shi, Limin Jia and Xin Zhang
Green energy as a transportation supply trend is irreversible. In this paper, a highway energy supply system (HESS) evolution model is proposed to provide highway transportation…
Abstract
Purpose
Green energy as a transportation supply trend is irreversible. In this paper, a highway energy supply system (HESS) evolution model is proposed to provide highway transportation vehicles and service facilities with a clean electricity supply and form a new model of a source-grid-load-storage-charge synergistic highway-PV-WT integrated system (HPWIS). This paper aims to improve the flexibility index of highways and increase CO2 emission reduction of highways.
Design/methodology/approach
To maximize the integration potential, a new energy-generation, storage and information-integration station is established with a dynamic master–slave game model. The flexibility index is defined to evaluate the system ability to manage random fluctuations in power generation and load levels. Moreover, CO2 emission reduction is also quantified. Finally, the Lianhuo Expressway is taken as an example to calculate emission reduction and flexibility.
Findings
The results show that through the application of the scheduling strategy to the HPWIS, the flexibility index of the Lianhuo Expressway increased by 29.17%, promoting a corresponding decrease in CO2 emissions.
Originality/value
This paper proposed a new model to capture the evolution of the HESS, which provides highway transportation vehicles and service facilities with a clean electricity supply and achieves energy transfer aided by an energy storage system, thus forming a new model of a transportation energy system with source-grid-load-storage-charge synergy. An evaluation method is proposed to improve the air quality index through the coordination of new energy generation and environmental conditions, and dynamic configuration and dispatch are achieved with the master–slave game model.