Jiabao Pan, Rui Li and Ao Wang
The adverse effects of temperature on the lubricating properties of nano magnetorheological grease are reduced by applying of a magnetic field.
Abstract
Purpose
The adverse effects of temperature on the lubricating properties of nano magnetorheological grease are reduced by applying of a magnetic field.
Design/methodology/approach
Nano magnetorheological grease was prepared via a thermal water bath with stirring. The lubricating properties of the grease were investigated at different temperatures. Then the lubricity of the prepared nano magnetorheological grease was investigated under the effect of thermomagnetic coupling.
Findings
As the temperature rises, the coefficient of friction of grease lubrication gradually increases, surface wear gradually increases and lubrication performance gradually decreases. Compared with grease, magnetorheological grease has a decreased coefficient of friction and enhanced lubrication effect under the action of a magnetic field at different temperatures.
Originality/value
A lubrication method using a magnetic field to reduce the effect of temperature is established, thereby providing new ideas for lubrication design under a wide range of temperature conditions.
Details
Keywords
Jiabao Pan, Huaibiao Wu, Ao Wang, Qingwen Dai and Xiaolei Wang
This paper aims to investigate the influence of high-temperature thermal action on grease performance from the angle of film-forming performance.
Abstract
Purpose
This paper aims to investigate the influence of high-temperature thermal action on grease performance from the angle of film-forming performance.
Design/methodology/approach
A static thermal aging method was used to prepare high-temperature thermal grease samples after high-temperature thermal action. On the basis of optical interference technology, the film-forming characteristics of fresh grease samples and the grease samples after high-temperature thermal action under variable speed and fixed speed conditions were explored.
Findings
The decrease in the structural entanglement performance of the grease after short-term high-temperature thermal action makes its film-forming performance better. The mechanism is that the lubricating grease soap fiber entanglement is reduced. Although the continuous high-temperature thermal action can make the grease film-forming performance better, its mechanism is that the soap fiber structure caused by high-temperature thermal action is damaged and is easy to be cut off under the action of shear.
Originality/value
The effect of structural system change on its film formation performance was discussed in combination with the change in grease structure characteristics, and the mechanism of action was revealed.
Details
Keywords
Fei Tong, Jie Yang, Meng Qiang Duan, Xu Fei Ma and Gao Chao Li
The purpose of this article is to understand the current research status and future development trends in the field of numerical simulation on rock mass grouting.
Abstract
Purpose
The purpose of this article is to understand the current research status and future development trends in the field of numerical simulation on rock mass grouting.
Design/methodology/approach
This article first searched the literature database (EI, Web of Science, CNKI, etc.) for keywords related to the numerical simulation of rock mass grouting to obtain the initial literature database. Then, from the initial database, several documents with strong relevance to the numerical simulation theme of rock mass grouting and high citation rate were selected; some documents from the references were selected as supplements, forming the sample database of this review study (a total of 90 articles). Finally, through sorting out the relationship among the literature, this literature review was carried out.
Findings
The numerical simulation of rock mass grouting is mainly based on the porous media model and the fractured media model. It has experienced the development process from Newtonian fluid to non-Newtonian fluid, from time-invariant viscosity to time-varying viscosity, and from generalized theoretical model to engineering application model. Based on this, this article summarizes four scientific problems that need to be solved in the future in this research field: the law of grout distribution at the cross fissures, the grout diffusion mechanism under multi-field coupling, more accurate grouting theoretical model and simulation technology with strong engineering applicability.
Originality/value
This research systematically analyzes the current research status and shortcomings of numerical simulation on rock mass grouting, summarizes four key issues in the future development of this research field and provides new ideas for the future research on numerical simulation on rock mass grouting.
Details
Keywords
Intuitionistic linguistic fuzzy information (ILFI), characterized by linguistic terms and intuitionistic fuzzy sets (IFSs), can easily express the fuzzy information in the process…
Abstract
Purpose
Intuitionistic linguistic fuzzy information (ILFI), characterized by linguistic terms and intuitionistic fuzzy sets (IFSs), can easily express the fuzzy information in the process of muticriteria decision making (MCDM) and muticriteria group decision making (MCGDM) problems. The purpose of this paper is to provide an overview of aggregation operators (AOs) and applications of ILFI.
Design/methodology/approach
First, some meaningful AOs for ILFI are summarized, and some extended MCDM approaches for intuitionistic uncertain linguistic variables (IULVs), such as extended TOPSIS, extended TODIM, extended VIKOR, are discussed. Then, the authors summarize and analyze the applications about the AOs of IULVs.
Findings
IULVs, characterized by linguistic terms and IFSs, can more detailed and comprehensively express the criteria values in the process of MCDM and MCGDM. Therefore, lots of researchers pay more and more attention to the MCDM or MCGDM methods with IULVs.
Originality/value
The authors summarize and analyze the applications about the AOs of IULVs Finally, the authors point out some possible directions for future research.
Details
Keywords
Hafiz Muhammad Athar Farid and Muhammad Riaz
The authors develop some prioritized operators named Pythagorean fuzzy prioritized averaging operator with priority degrees and Pythagorean fuzzy prioritized geometric operator…
Abstract
Purpose
The authors develop some prioritized operators named Pythagorean fuzzy prioritized averaging operator with priority degrees and Pythagorean fuzzy prioritized geometric operator with priority degrees. The properties of the existing method are routinely compared to those of other current approaches, emphasizing the superiority of the presented work over currently used methods. Furthermore, the impact of priority degrees on the aggregate outcome is thoroughly examined. Further, based on these operators, a decision-making approach is presented under the Pythagorean fuzzy set environment. An illustrative example related to the selection of the best alternative is considered to demonstrate the efficiency of the proposed approach.
Design/methodology/approach
In real-world situations, Pythagorean fuzzy numbers are exceptionally useful for representing ambiguous data. The authors look at multi-criteria decision-making issues in which the parameters have a prioritization relationship. The idea of a priority degree is introduced. The aggregation operators are formed by awarding non-negative real numbers known as priority degrees among strict priority levels. Consequently, the authors develop some prioritized operators named Pythagorean fuzzy prioritized averaging operator with priority degrees and Pythagorean fuzzy prioritized geometric operator with priority degrees.
Findings
The authors develop some prioritized operators named Pythagorean fuzzy prioritized averaging operator with priority degrees and Pythagorean fuzzy prioritized geometric operator with priority degrees. The properties of the existing method are routinely compared to those of other current approaches, emphasizing the superiority of the presented work over currently used methods. Furthermore, the impact of priority degrees on the aggregate outcome is thoroughly examined. Further, based on these operators, a decision-making approach is presented under the Pythagorean fuzzy set environment. An illustrative example related to the selection of the best alternative is considered to demonstrate the efficiency of the proposed approach.
Originality/value
The aggregation operators are formed by awarding non-negative real numbers known as priority degrees among strict priority levels. Consequently, the authors develop some prioritized operators named Pythagorean fuzzy prioritized averaging operator with priority degrees and Pythagorean fuzzy prioritized geometric operator with priority degrees. The properties of the existing method are routinely compared to those of other current approaches, emphasizing the superiority of the presented work over currently used methods. Furthermore, the impact of priority degrees on the aggregate outcome is thoroughly examined.
Details
Keywords
Shuwen Wang, Feiyan Yan and Ao Chen
The purpose of this paper is to investigate the tribological effects of laser surface texturing (LST) and residual stress on functional surfaces.
Abstract
Purpose
The purpose of this paper is to investigate the tribological effects of laser surface texturing (LST) and residual stress on functional surfaces.
Design/methodology/approach
Three different surface textures (circular dimple, elliptical dimple and groove) with two different textured area ratios (10 and 20 per cent) are designed and fabricated by a Picosecond Nd YAG Laser machine. The friction and wear performance of textured specimens is tested using a UMT-2 friction and wear testing machine in mixed lubrication.
Findings
Test results show that elliptical dimples exhibit the best performance in wear resistance, circular dimples in friction reduction and grooves in stabilization of friction. The surfaces with larger textured area density exhibit better performance in both friction reduction and wear resistance. The improved performance of LST is the coupled effect of surface texture and residual stress.
Originality/value
The findings of this study may provide guidance for optimal design of functional surface textures in reciprocating sliding contacts under mixed or hydrodynamic lubrication, which can be used in automotive and other industrial applications.
Details
Keywords
Lazim Abdullah, Herrini Mohd Pouzi and Noor Azzah Awang
This study aims to develop a cause-effect relationship between criteria that contribute to water security using the Intuitionistic Fuzzy-Decision-Making Trial and Evaluation…
Abstract
Purpose
This study aims to develop a cause-effect relationship between criteria that contribute to water security using the Intuitionistic Fuzzy-Decision-Making Trial and Evaluation Laboratory (IF-DEMATEL) method. Differently from the typical DEMATEL which utilizes crisp numbers, this modification introduces intuitionistic fuzzy numbers (IFNs) to enhance judgments in a group decision-making environment. In particular, the linguistic variables used in IF-DEMATEL are defined using the concept of three-tuple of IFNs.
Design/methodology/approach
Data with the linguistic variable “influence” were collected from a group of experts in water security via personal unstructured interviews. Seven water security criteria are considered in this study. Computational software was employed to execute the computational procedures of the IF-DEMATEL method. It is anticipated that by taking into account the hesitation degree of IFNs will reflect the scenario in real life, which could lead to precise decision-making.
Findings
The results show that “Over-Abstraction”, “Saltwater Intrusion” and “Limited Infrastructures” are the cause criteria that contribute to water security. In addition, the relationship map of influence shows that “Water Pollution” and “Rapid Urbanization” are the most vulnerable criteria as these two criteria are most easily affected by other criteria in a unidirectional relation.
Practical implications
It is anticipated that these findings will serve as useful references for water security management and policymakers.
Originality/value
The present study makes a noteworthy contribution to the modification of DEMATEL where three-tuple of intuitionistic fuzzy numbers are considered in the computations. The present study also provides additional evidence with respect to factors that contribute to water security.
Details
Keywords
Huayi Li, Qingxian Jia, Rui Ma and Xueqin Chen
The purpose of this paper is to accomplish robust actuator fault isolation and identification for microsatellite attitude control systems (ACSs) subject to a series of space…
Abstract
Purpose
The purpose of this paper is to accomplish robust actuator fault isolation and identification for microsatellite attitude control systems (ACSs) subject to a series of space disturbance torques and gyro drifts.
Design/methodology/approach
For the satellite attitude dynamics with Lipschitz constraint, a multi-objective nonlinear unknown input observer (NUIO) is explored to accomplish robust actuator fault isolation based on a synthesis of Hinf techniques and regional pole assignment technique. Subsequently, a novel disturbance-decoupling learning observer (D2LO) is proposed to identify the isolated actuator fault accurately. Additionally, the design of the NUIO and the D2LO are reformulated into convex optimization problems involving linear matrix inequalities (LMIs), which can be readily solved using standard LMI tools.
Findings
The simulation studies on a microsatellite example are performed to prove the effectiveness and applicability of the proposed robust actuator fault isolation and identification methodologies.
Practical implications
This research includes implications for the enhancement of reliability and safety of on-orbit microsatellites.
Originality/value
This study proposes novel NUIO-based robust fault isolation and D2LO-based robust fault identification methodologies for spacecraft ACSs subject to a series of space disturbance torques and gyro drifts.
Details
Keywords
Wang Kangmao and Hu Chun
This paper identifies the new economic force regenerating the East Asian economies in the post‐crisis era. Based on the convergence of five main economic indexes, it reclassifies…
Abstract
This paper identifies the new economic force regenerating the East Asian economies in the post‐crisis era. Based on the convergence of five main economic indexes, it reclassifies the ten East Asian entities into four tiers, and highlights the language similarities among the tiers. It also discusses the inter‐ and intra‐regional economic dynamics, and the implications on further regional trade/investment, financial cooperation and monetary integration, such as a possible unifying Asian currency.
Details
Keywords
Seyi S. Stephen, Ayodeji E. Oke, Clinton O. Aigbavboa, Opeoluwa I. Akinradewo, Pelumi E. Adetoro and Matthew Ikuabe
The chapter discussed the comprehensive integration of whole life cycle (WLC) principles in construction, mainly focusing on its application in stealth construction. It outlined…
Abstract
The chapter discussed the comprehensive integration of whole life cycle (WLC) principles in construction, mainly focusing on its application in stealth construction. It outlined the challenges of implementing WLC practices, emphasising the need for proactive planning and meticulous execution. The study highlighted key aspects of the WLC in stealth construction, including considerations for building design, energy transmission, visibility management, and security countermeasures. Additionally, it underscores the importance of addressing environmental protection, health and safety, project delivery duration, economy, and aesthetics throughout the construction process to ensure the development of resilient, sustainable, and visually appealing structures that meet the needs of present and future generations.