Zhixiong Chen, Weishan Long, Li Song and Xinglin Li
This paper aims to research the tribological and dynamic characteristics of aeroengine hybrid ceramic bearings through wear experiments and simulation analysis.
Abstract
Purpose
This paper aims to research the tribological and dynamic characteristics of aeroengine hybrid ceramic bearings through wear experiments and simulation analysis.
Design/methodology/approach
First, the authors carried out wear experiments on Si3N4–GCr15 and GCr15–GCr15 friction pairs through the ball-disc wear test rig to explore the tribological properties of their materials. Second, using ANSYS/LS-DYNA simulation software, the dynamic simulation analysis of hybrid bearings was carried out under certain working conditions, and the dynamic contact stress of all-steel bearings of the same size was simulated and compared. Finally, the change of the maximum contact stress of the main bearing under the change of load and rotation speed was studied.
Findings
The results show that the Si3N4–GCr15 pair has better tribological performance. At the same time, under the conditions of high speed and heavy load, the simulation analysis shows that the contact stress between the ceramic ball and the raceway of the ring is smaller than the steel ball. That is, hybrid bearings have better transient mechanical properties than all-steel bearings. With the speed increasing to 12,000 r/min, the maximum stress point will shift in the inner and outer rings.
Originality/value
In this study, the tribological and transient mechanical properties of Si3N4 material were comprehensively analyzed through wear experiments and dynamic simulation analysis, which provided a reference for the design of hybrid bearings for next-generation aeroengines.
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Junfu Xiao, Siying Chen, Zhixiong Tan, Yanyu Chen, Jiayi Wang and Han Jingwei
Given the inevitable transition to renewable resource utilization and the urgent need to reduce carbon emissions, this study conducted quasi natural experiments to assess the…
Abstract
Purpose
Given the inevitable transition to renewable resource utilization and the urgent need to reduce carbon emissions, this study conducted quasi natural experiments to assess the impact of renewable resource utilization on carbon emissions based on the national “urban mining” demonstration bases (NUMDB).
Design/methodology/approach
This study uses panel data from 275 prefecture-level cities in China from 2006 to 2019. The paper selects NUMDB as the proxy variable and conducts a quasi-natural experiment using a multi-period differences-in-differences model. We examine the impact of NUMDB on reducing carbon emissions, and then deeply explore its mechanism and spatial spillover effect.
Findings
This study found that: (1) the construction of NUMDB can significantly decrease the carbon emission in the host cities; (2) NUMDB’s construction has more significantly reduced the carbon emission in regions with higher levels of circular economy development, green technology innovation, regional environmental pollution, digital economy development and financial development; (3) by means of green technology innovation, optimized energy structure, and high-quality talent aggregation, NUMDB reduces urban carbon emissions; (4) NUMDB construction positively affects the carbon reduction efficiency of neighboring regions.
Research limitations/implications
We propose corresponding policy suggestions to further promote the carbon emission reduction effect of NUMDB and develop the renewable resources industry in China based on the research findings.
Practical implications
The contributions of this paper are as follows. Our study contributes to expanding the research scope on the environmental impact of the renewable resource industry, as there are few quantitative studies in this area.
Social implications
We further consider the spatial heterogeneity of policies and analyze the carbon reduction effect of the NUMDB from the city level, which is beneficial to exploring more targeted and operable carbon reduction paths.
Originality/value
This study on identifying the causal relationship between renewable resource utilization and carbon emission reduction helps to explore the sustainable development path of renewable resource more comprehensively. Meanwhile, this paper provides a reference for other countries to improve the utilization of renewable resource and effectively reduce carbon emissions.
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Haiyan Wang, Jiayu Fu, Li Mei, Xiangrong Xu, Shanshan Xu, Zhixiong Wang and Ri Su Na
This study aims to obtain the speed and angle during safe and comfortable standing of elderly people. With the advancement of society, it is becoming increasingly difficult for…
Abstract
Purpose
This study aims to obtain the speed and angle during safe and comfortable standing of elderly people. With the advancement of society, it is becoming increasingly difficult for the elderly to sit-to-stand (STS) independently and comfortably in a safe and comfortable manner. Safety is essentially a prerequisite for the elderly to achieve a comfortable STS. The speed, angle and power of the STS process can all affect safe STS. From the standpoint of health-care delivery and administration, comfortable STS can be realized easily by addressing the safety issues during STS.
Design/methodology/approach
This paper summarizes the research progress on speed and angle during safe and comfortable standing of older people. The authors analyzed the speed and angle of the STS using the Vicon optical gait acquisition system and plantar pressure sensor to find the appropriate angle and speed thresholds.
Findings
The center of gravity movement is a prerequisite for the elderly to achieve a comfortable STS. The authors found that the standing speed during the STS process should not be higher than 103.8 mm/s so that the elderly can stand comfortably and safely (safe and dangerous speeds are 72.8 mm/s and 125.2 mm/s). The limitations of waist angle, waist angle speed and the acceleration are also obtained.
Originality/value
This paper analyzes and summarizes the research status of speed and angle during safe and comfortable standing of elderly people, which is essentially a prerequisite for the elderly to achieve a comfortable STS. These results can lay the foundation for the development of assistive devices and related technologies that meet the needs of older adults.
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Serhat Yüksel, Hasan Dinçer, Çağatay Çağlayan and Gülsüm Sena Uluer
Carbon emission is one of the most important problems of today. In this framework, it is important for countries to take the necessary actions to solve this problem. Energy use is…
Abstract
Carbon emission is one of the most important problems of today. In this framework, it is important for countries to take the necessary actions to solve this problem. Energy use is one of the most important causes of carbon emissions. Choosing fossil fuels in this process increases the carbon emission problem. Therefore, it is understood that countries should be more sensitive about energy types. In this context, renewable energy (RE) sources are recommended by experts. However, due to some problems of these energy types, it does not seem possible to meet all energy needs from these sources. It is thought that nuclear energy will produce a permanent solution to the carbon emission problem. In this context, it is recommended that the use of nuclear energy be put on the agenda by countries.
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M. Sheikholeslami, Hakan F. Öztop, Nidal Abu-Hamdeh and Zhixiong Li
The purpose of this paper is to research on CuO-water nanofluid Non-Darcy flow because of magnetic field. Porous cavity has circular heat source and filled with nanofluid. Lattice…
Abstract
Purpose
The purpose of this paper is to research on CuO-water nanofluid Non-Darcy flow because of magnetic field. Porous cavity has circular heat source and filled with nanofluid. Lattice Boltzmann Method (LBM) has been used to simulate this problem.
Design/methodology/approach
In this research, LBM has been applied as mesoscopic approach to simulate water-based nanofluid free convection. Koo–Kleinstreuer–Li model is used to consider Brownian motion impact on nanofluid properties. Impacts of Rayleigh number, Darcy number, nanofluid volume fraction and Hartmann number on heat transfer treatment are illustrated.
Findings
It is found that temperature gradient decreases with rise of while it enhances with augment of Ha. Darcy number can enhance the convective flow.
Originality/value
The originality of this work is to analyze the to investigate magnetic field impact on water based CuO-H2O nanofluid natural convection inside a porous cavity with elliptic heat source.
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Jianmei Wang, Zhixiong Li, Sadoughi Mohammadkazem, Min Cai, Jianfeng Kang and Yanan Zhang
The stability characteristics of an oil film directly influence the safety and service life of mill oil-film bearings. However, very limited work has been done to address the…
Abstract
Purpose
The stability characteristics of an oil film directly influence the safety and service life of mill oil-film bearings. However, very limited work has been done to address the stability characteristics of mill oil-film bearings. To this end, this paper aims to investigate the stability characteristics of mill oil-film bearings through theoretical and experimental analysis.
Design/methodology/approach
For the first time, a special designed experiment platform was developed to investigate the stability characteristics of mill oil-film bearings. In addition, a theoretical model of lubricating film of the tested bearings was established to analyze the oil-film stability. The theoretical results were compared with the experimental results.
Findings
The comparison results demonstrate that the critical influential factors on the bearing stability were the eccentricity ratio and the ratio of bearing length to diameter. The mill bearing was likely to be unstable under a small load and at a high rotational speed.
Practical implications
The paper includes implications for suitable operation conditions in practical use of mill oil-film bearings.
Originality/value
This paper fulfills an identified need to investigate oil-film stability of mill bearings for practical applications.
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Zafer Adalı, Hasan Dinçer, Serkan Eti, Alexey Mikhaylov and Serhat Yüksel
This chapter aims to identify new perspectives of geothermal energy investments. For this purpose, all studies in the Web of Science regarding the geothermal energy are taken into…
Abstract
This chapter aims to identify new perspectives of geothermal energy investments. For this purpose, all studies in the Web of Science regarding the geothermal energy are taken into consideration. These studies are evaluated with the help of text-mining approach. In this framework, most frequently stated words, two words, and three words are identified. It is concluded that technological development with respect to the geothermal energy is an important issue in this framework. After that, it is also determined that risk is another important factor in this regard. Finally, new implications regarding the geothermal energy are also considered by the researchers. Geothermal energy has a positive contribution to solve many different problems, such as energy dependency, current account deficit problem, and carbon emission. Hence, this study generated the significant issues to improve these investments. While considering the results, it is understood that technological developments related to the geothermal energy projects should be followed effectively. In addition, an effective risk evaluation should be conducted before implementing these projects.
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Manh-Hoang Do, Yung-Fu Huang and Vu-Dung-Van Phan
This research study aims to identify and rank the most substantial barriers to implementing green supply chain management (GSCM) in the Vietnamese agriculture industry.
Abstract
Purpose
This research study aims to identify and rank the most substantial barriers to implementing green supply chain management (GSCM) in the Vietnamese agriculture industry.
Design/methodology/approach
The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) techniques have been employed for this work to rank the critical GSCM barriers. The rankings were determined based on the expertise and input of ten experts from Vietnamese agriculture firms who participated as respondents.
Findings
This study has identified seven clusters of barriers, which encompass a total of 19 sub-barriers. Among these obstacles, the categories of financial costs and external stakeholders have emerged as the top priority barriers that require immediate attention and resolution. Meanwhile, the technology and strategic management clusters have a relatively weaker impact on GSCM implementation.
Practical implications
These findings provide valuable guidelines for the top managers in this sector to consider before systematically deciding on the GSCM implementation problems to improve performance and competitive advantage.
Originality/value
This work focuses on considering GSCM barriers for the Vietnamese agriculture industry; hence, it enriches the GSCM literature by offering perspectives from a transitional market, which results in variations in the barriers, categorization and importance ranking.
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B. Mahanthesh, T. Brizlyn, SabirAli Shehzad and Gireesha B.J.
The nonlinear density thermal/solutal fluctuations in the buoyancy force term cannot be ignored when the temperature/concentration difference between the surface and fluid is…
Abstract
Purpose
The nonlinear density thermal/solutal fluctuations in the buoyancy force term cannot be ignored when the temperature/concentration difference between the surface and fluid is large. The purpose of this paper is to investigate the nonlinear density fluctuations across a flowing fluid with heat mass transfer effects on a non-axial rotating plate. Therefore, the impact of nonlinear convection in the flow of Casson fluid over an oscillating plate has been analytically investigated.
Design/methodology/approach
The governing equations are modeled with the help of conservation equations of velocity, energy and concentration under the transient-state situation. The dimensional governing equations are non-dimensionalized by utilizing non-dimensional variables. Later, the subsequent non-dimensional problem has been solved analytically using Laplace transform method.
Findings
The effects of thermal Grashof number, solute Grashof number, nonlinear convection parameters, Casson fluid parameter, unsteady parameter, Prandtl number as well as Schmidt number on hydrodynamic, thermal and solute characteristics have been quantified. The numeric data for skin friction coefficient, Nusselt number and Sherwood number are presented. It is established the nonlinear convection aspect has a significant influence on heat and mass transport characteristics.
Originality/value
The effect of nonlinear convection in the dynamics of Casson fluid past an oscillating plate which is rotating non-axially is investigated for the first time.