Wang Dong, Li Zhuangyun and Zhu Yuquan
In recent years water hydraulic systems have become of major interest because of the human friendly and environmental safety aspects. The piston pump is one of the most frequently…
Abstract
In recent years water hydraulic systems have become of major interest because of the human friendly and environmental safety aspects. The piston pump is one of the most frequently used hydraulic units in recent engineering techniques. In a water hydraulic piston pump, poor lubrication is more likely to happen than in a oil hydraulic one because of differences in properties between water and oil. There are some key problems, such as corrosive wear and erosion, which are briefly investigated in this paper. Many new materials have been developed, which give longer life expectancies in water without corrosion and erosion. Recently, a new type of seawater hydraulic piston pump with better suction characteristics had been developed at Huazhong University of Science and Technology, China. Much of this research has concentrated on new materials, structure and experiments, which are also specially introduced in this paper.
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Dong Wang, Zhuangyun Li, Yuquan Zhu and Lijun He
The dynamic process of purifying emulsion using electromagnetic technique has been analyzed and studied via dynamics principles in this paper. Based on results, the purification…
Abstract
The dynamic process of purifying emulsion using electromagnetic technique has been analyzed and studied via dynamics principles in this paper. Based on results, the purification equipment has been developed and installed in a cold rolling mill. The basic structure characteristics of the purification equipment were described in detail. The equipment of purifying emulsion using electromagnetic technique is of excellent characteristics, which has a strong magnetic field, low flow velocity and multi‐pass of emulsion. Emulsion purified in this way can be recycled and used again with cost reduction. The equipment can be used in many fields such as cold rolling mill and machinery.
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Maneerat Kanrak, Hong Oanh Nguyen and Yuquan Du
This paper presents a critical review of the economic network analysis methods and their applications to maritime transport. A network can be presented in terms of its structure…
Abstract
This paper presents a critical review of the economic network analysis methods and their applications to maritime transport. A network can be presented in terms of its structure, topology, characteristics as well as the connectivity with different measures such as density, degree distribution, centrality (degree, betweenness, closeness, eigenvector and strength), clustering coefficient, average shortest path length and assortative. Various models such as the random graph model, block model, and ERGM can be used to analyse and explore the formation of a network and interaction between nodes. The review of the existing theories and models has found that, while these models are rather computationally intensive, they are based on some rather restrictive assumption on network formation and relationship between ports in the network at the local and global levels that require further investigation. Based on the review, a conceptual framework for maritime transport network research is developed, and the applications for future research are also discussed.
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Maneerat Kanrak, Hong Oanh Nguyen and Yuquan Du
This paper presents a critical review of the economic network analysis methods and their applications to maritime transport. A network can be presented in terms of its structure…
Abstract
This paper presents a critical review of the economic network analysis methods and their applications to maritime transport. A network can be presented in terms of its structure, topology, characteristics as well as the connectivity with different measures such as density, degree distribution, centrality (degree, betweenness, closeness, eigenvector and strength), clustering coefficient, average shortest path length and assortative. Various models such as the random graph model, block model, and ERGM can be used to analyse and explore the formation of a network and interaction between nodes. The review of the existing theories and models has found that, while these models are rather computationally intensive, they are based on some rather restrictive assumption on network formation and relationship between ports in the network at the local and global levels that require further investigation. Based on the review, a conceptual framework for maritime transport network research is developed, and the applications for future research are also discussed.
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Yuquan Ni, Nannan Sun, Guixiang Zhu, Shujie Liu, Jun Liu and Guangneng Dong
This paper aims to study different morphology Cu6Sn5 effect on Babbitt alloy tribological properties.
Abstract
Purpose
This paper aims to study different morphology Cu6Sn5 effect on Babbitt alloy tribological properties.
Design/methodology/approach
Different morphology Cu6Sn5 of Babbitt was conducted by different cooling modes. Bare Babbitt was marked by Babbitt-0, Babbitt modified by first cooling mode (marked by Babbitt-1) and Babbitt modified by second cooling mode (marked by Babbitt-2). The microstructure and microhardness of specimens were tested. Then, tribological properties of Babbitt-0, Babbitt-1 and Babbitt-2 were performed by reciprocating mode under lubricated condition.
Findings
The results showed that shape Cu6Sn5 of Babbitt was changed from mixed needle and star-like shape to short rod-like or granular shape. The microhardness of Babbitt-1 was highest than that of Babbitt-0 and Babbitt-2. Compared with Babbitt-0 and Babbitt-2, tribological properties of Babbitt-1 were better under lubricated condition due to short rod-like and sparse distribution of Cu6Sn5. Moreover, the simulation result of strain and stress of Babbitt-1 was lowest than that of Babbitt-0 and Babbitt-2.
Originality/value
Different morphology (shape and distributed) of Cu6Sn5 was obtained by different cooling modes. Modulated different forms of Cu6Sn5 around SnSb was beneficial to improve Babbitt alloy tribological properties.
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This paper aims to investigate the grey scheduling, which is the combination of grey system theory and scheduling problems with uncertain processing time. Based on the interval…
Abstract
Purpose
This paper aims to investigate the grey scheduling, which is the combination of grey system theory and scheduling problems with uncertain processing time. Based on the interval grey number and its related definitions, properties, and theorems, the single machine scheduling with uncertain processing time and its general forms are studied as the research object. Then several single machine scheduling models are reconstructed, and an actual production case is developed to illustrate the rationality of the research.
Design/methodology/approach
In this paper, the authors first summarize the definitions and properties related to interval grey numbers, especially the transitivity of the partial order of interval grey numbers, and give an example to illustrate that the transitivity has a positive effect on the computational time complexity of multiple interval grey number comparisons. Second, the authors redefine the general form of the single machine scheduling problem with uncertain processing time according to the definitions and theorems of interval grey numbers. The authors then reconstruct three single machine scheduling models with uncertain processing time, give the corresponding heuristic algorithms based on the interval grey numbers and prove them. Finally, the authors develop a case study based on the engine test shop of K Company, the results show that the proposed single machine scheduling models and algorithms with uncertain processing time can provide effective guidance for actual production in an uncertain environment.
Findings
The main findings of this paper are as follows: (1) summarize the definitions and theorems related to interval grey numbers and prove the transitivity of the partial order of interval grey numbers; (2) define the general form of the single machine scheduling problem with interval grey processing time; (3) reconstruct three single machine scheduling models with uncertain processing time and give the corresponding heuristic algorithms; (4) develop a case study to illustrate the rationality of the research.
Research limitations/implications
In the further research, the authors will continue to summarize more advanced general forms of grey scheduling, improve the theory of grey scheduling and prove it, and further explore the application of grey scheduling in the real world. In general, grey scheduling needs to be further combined with grey system theory to form a complete theoretical system.
Originality/value
It is a fundamental work to define the general form of single machine scheduling with uncertain processing time used the interval grey number. However, it can be seen as an important theoretical basis for the grey scheduling, and it is also beneficial to expand the application of grey system theory in real world.
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Canjun Yang, Hansong Wang, Qihang Zhu, Xiangzhi Liu, Wei Yang, Zhangyi Ma and Qianxiao Wei
Lower extremity exoskeletons have drawn much attention recently due to their potential ability to help the stroke and spinal cord injury patients to regain the ability of walking…
Abstract
Purpose
Lower extremity exoskeletons have drawn much attention recently due to their potential ability to help the stroke and spinal cord injury patients to regain the ability of walking. However, the balance of the human-exoskeleton system (HES) remains a big challenge. Usually, patients use crutches to keep balance when they wear exoskeleton. However, the balance depends greatly on the patient's balance ability and will be inevitably poor occasionally, which often causes the landing in advance of HES. The purpose of this paper is to propose a real-time stepping gait trajectory planning method based on the hip height variation of the swing leg to solve the problem.
Design/methodology/approach
The hip height of the swing leg was analyzed and measured. The simulation with MATLAB and the experimental test with the prototype of the proposed gait were conducted to verify its feasibility.
Findings
With the proposed method, HES can achieve successful step even when the balance kept by crutches is poor.
Research limitations/implications
Instead of actively avoiding the poor balance due to the instability caused by gravity, the method just modifies the stepping gait passively to avoid the landing in advance when the poor balance appears. In addition, it may not work well when the balance is too poor. Moreover, the proposed gait is just used in the initial stage of rehabilitation training. Besides, the step length of the gait must be limited for comfort.
Originality/value
A real-time stepping gait trajectory planning method based on the hip height variation of the swing leg is first proposed and its feasibility to avoid the landing in advance when the balance kept by the crutches is poor has been preliminary verified.
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Yuquan Ni, Peng Guo, Chonggang Ren, Jicai Yin and Bingchuan Bian
The grain size and grain distribution mode have a significant impact on the tribological properties of Babbitt alloy. The purpose of this paper is to study the effect of…
Abstract
Purpose
The grain size and grain distribution mode have a significant impact on the tribological properties of Babbitt alloy. The purpose of this paper is to study the effect of differentiated SnSb grain size distribution on the improvement of tribological properties of Babbitt alloy.
Design/methodology/approach
Babbitt (marked by babbitt-cr), with a differentiated SnSb grain size distribution, was fabricated using a selective zone laser surface treatment. Bare Babbitt with coarse SnSb grain was marked as babbitt-c, and Babbitt with refined SnSb grain was marked as babbitt-r. The microstructure, microhardness and wettability of specimens were tested. The tribological properties of babbitt-c, babbitt-r and babbitt-cr were evaluated under dry and lubricated conditions.
Findings
The microstructure transforms from single coarse SnSb grain distribution or single refined SnSb grain distribution to differentiated SnSb grain size distribution, as a result of selective zone laser surface treatment. Among three specimens of microhardness, babbitt-cr showed the highest microhardness. The lipophilicity property of babbitt-cr was better compared to babbitt-c. A mixture of coarse and refined grain is beneficial to improve the tribological properties of Babbitt alloy under dry condition. Furthermore, compared with babbitt-c, the wear resistance of babbitt-cr was enhanced under lubricated condition. However, the anti-wear property of babbitt-cr was not significantly improved relative to babbitt-r with an increase in the loads.
Originality/value
The study demonstrates that modulated different grain size alternating distribution modes can improve the tribological properties of Babbitt alloy.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2022-0259/
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Lei Zhang, Chengkun Qu, Shuzhan Zhang, Ying Li, Changjun Li and Yuquan Lu
Damage to the pipe structure and increased bolt stress in operating tunnels will significantly affect the long-term stability of shield tunnels. However, due to the large number…
Abstract
Purpose
Damage to the pipe structure and increased bolt stress in operating tunnels will significantly affect the long-term stability of shield tunnels. However, due to the large number of segments and complex bolt installation methods, it is difficult to directly obtain the conditions of segments and bolts. Convergence deformation, as an important indicator for the health assessment of operating tunnels, is easy to collect and can directly reflect the structural state of tunnel segments and bolts.
Design/methodology/approach
Taking the typical sections of Hangzhou Metro Line 1 and Line 3 as an example, the current structural damage is simulated by monitoring tunnel convergence deformation. First, based on the disease data, the relationship between convergence deformation and segment leakage, segment misalignment as well as the longitudinal joint opening between two segments is analyzed statistically. The stress of bolts, steel bars and segments under different convergence deformations is simulated by Midas. Then a reinforcement measure of circumferential internal tension steel rings is proposed.
Findings
It is found that when the segment convergence exceeds 85 mm, although the overall force on the segment has not reached the material limit, there are certain safety risks in the structure. After comparison, the reinforcement measure has a relatively significant effect on controlling the lateral deformation of segments.
Originality/value
The results have important guiding significance for the evaluation of structural diseases, early warning and control of structural diseases at different convergence deformations.
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Son Nguyen, Peggy Shu-Ling Chen and Yuquan Du
Although being considered for adoption by stakeholders in container shipping, application of blockchain is hindered by different factors. This paper investigates the potential…
Abstract
Purpose
Although being considered for adoption by stakeholders in container shipping, application of blockchain is hindered by different factors. This paper investigates the potential operational risks of blockchain-integrated container shipping systems as one of such barriers.
Design/methodology/approach
Literature review is employed as the method of risk identification. Scientific articles, special institutional reports and publications of blockchain solution providers were included in an inclusive qualitative analysis. A directed acyclic graph (DAG) was constructed and analyzed based on network topological metrics.
Findings
Twenty-eight potential risks and 47 connections were identified in three groups of initiative, transitional and sequel. The DAG analysis results reflect a relatively well-connected network of identified hazardous events (HEs), suggesting the pervasiveness of information risks and various multiple-event risk scenarios. The criticality of the connected systems' security and information accuracy are also indicated.
Originality/value
This paper indicates the changes of container shipping operational risk in the process of blockchain integration by using updated data. It creates awareness of the emerging risks, provides their insights and establishes the basis for further research.