Haifei Zheng, Yanguo Yin, Rongrong Li, Cong Liu and Qi Chen
This paper aims to investigate the effect of chemical nickel plating and mechanical alloying on the mechanical and tribological properties of FeS/iron-based self-lubricating…
Abstract
Purpose
This paper aims to investigate the effect of chemical nickel plating and mechanical alloying on the mechanical and tribological properties of FeS/iron-based self-lubricating materials as well as the wear mechanism of the materials.
Design/methodology/approach
Surface modification of FeS powder was carried out by chemical nickel plating method and mechanical alloying of mixed powder by ball milling. The mechanical properties of the material were tested by tribological testing by M-200 ring block type friction and wear tester. Optical microscope was used to observe the surface morphology of the material and the transfer film on the surface of the mate parts, and scanning electron microscope and EDS were used to characterize the wear surface.
Findings
Mechanical alloying ball milling was carried out so that the lubricating particles in the matrix are uniformly dispersed; nickel-plated layer enhances the interfacial bonding of FeS and the matrix, and the combination of the two improves the mechanical properties of the material, and at the same time the friction side of the surface of the lubrication of FeS lubricant transfer film formed is denser and more intact, and the friction coefficient of friction side and the wear rate of the material have been greatly reduced.
Originality/value
This work aims to improve the mechanical and tribological properties of FeS/iron-based self-lubricating materials and to provide a reference for the preparation of materials with excellent overall properties.
Details
Keywords
Jiayuan Hu, Zhixing Fang, Zhouhai Qian, Xiaoming Shen, Haifei Zhou and Dongchun Jin
The purpose of this paper is to study the cause of severe corrosion of the galvanized lightning rods in a 220 kV transformer substation, and to seek the effective corrosion…
Abstract
Purpose
The purpose of this paper is to study the cause of severe corrosion of the galvanized lightning rods in a 220 kV transformer substation, and to seek the effective corrosion inhibition measures for the hollow lightning rods.
Design/methodology/approach
The corrosion morphology and rust component of lightning rod was analyzed, and the corrosion process of lightning rod was researched by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), ion chromatography and electrochemical tests.
Findings
The results indicated that the outer surface of hollow lightning rod was corroded slightly; however, its inner surface suffered severe corrosion because of a long time high-humidity environment inside the tube caused by the rainwater permeation. A rust layer consisted of Fe3O4 and a little FeOOH was accumulated on the inner surface of the hollow lightning rod. Moreover, Fe3O4 rust layer worked as a large cathode area which could promote the corrosion of metal substrate further. A self-accelerating corrosion process was formed on the inner surface, making the corrosion failure of lightning rod occurred and aggravated gradually.
Originality/value
The corrosion of inner surface of hollow lightning rod cannot be detected easily. More attention should be paid to the corrosion inhibition of lightning rod. The key of corrosion inhibition for the hollow lightning rod was to avoid the rainwater accumulation inside tube. The research results can provide guidelines on the corrosion inhibition measures selection of lightning rod in transformer substation.
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Xuefeng Zhou, Li Jiang, Yisheng Guan, Haifei Zhu, Dan Huang, Taobo Cheng and Hong Zhang
Applications of robotic systems in agriculture, forestry and high-altitude work will enter a new and huge stage in the near future. For these application fields, climbing robots…
Abstract
Purpose
Applications of robotic systems in agriculture, forestry and high-altitude work will enter a new and huge stage in the near future. For these application fields, climbing robots have attracted much attention and have become one central topic in robotic research. The purpose of this paper is to propose an energy-optimal motion planning method for climbing robots that are applied in an outdoor environment.
Design/methodology/approach
First, a self-designed climbing robot named Climbot is briefly introduced. Then, an energy-optimal motion planning method is proposed for Climbot with simultaneous consideration of kinematic constraints and dynamic constraints. To decrease computing complexity, an acceleration continuous trajectory planner and a path planner based on spatial continuous curve are designed. Simulation and experimental results indicate that this method can search an energy-optimal path effectively.
Findings
Climbot can evidently reduce energy consumption when it moves along the energy-optimal path derived by the method used in this paper.
Research limitations/implications
Only one step climbing motion planning is considered in this method.
Practical implications
With the proposed motion planning method, climbing robots applied in an outdoor environment can commit more missions with limit power supply. In addition, it is also proved that this motion planning method is effective in a complicated obstacle environment with collision-free constraint.
Originality/value
The main contribution of this paper is that it establishes a two-planner system to solve the complex motion planning problem with kinodynamic constraints.
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Pengcheng Xiang, Simai Yang, Yongqi Yuan and Ranyang Li
The purpose of this paper is to develop a comprehensive understanding of the public safety risks of international construction projects (ICPs) from the perspective of threat and…
Abstract
Purpose
The purpose of this paper is to develop a comprehensive understanding of the public safety risks of international construction projects (ICPs) from the perspective of threat and vulnerability. A novel and comprehensive risk assessment approach is developed from a systemic perspective and applied to the Belt and Road Initiative (BRI) to improve the public safety risk management strategy for ICPs in BRI.
Design/methodology/approach
First, a public safety risk indicator system was constructed from the two dimensions, namely threat and vulnerability. Next, an integrated measurement model was constructed by combining the Genetic Algorithm-Backpropagation (GA-BP) neural network, fuzzy comprehensive evaluation method and matter-element extension (MME) method. Data from 49 countries involved in the BRI, as well as five typical projects, were used to validate the model. Finally, targeted risk prevention measures were identified for use at the national, enterprise and project levels.
Findings
The findings indicate that while the vulnerability risks of typical projects in each region of the BRI were generally low, threat risks were high in West Asia and North Africa, Commonwealth of Independent States (CIS) countries and South Asia.
Originality/value
First, the structure of the public safety risk system of ICPs was analyzed using vulnerability and system theories. The connotation of public safety risk was defined based on two dimensions, namely threat and vulnerability. The idea of measuring threat risk with public data and measuring vulnerability risk with project data was clarified, and the risk measurement was integrated into the measurement results to help researchers and managers understand and systematically consider the public safety risks of ICPs. Second, a public safety risk indicator system was constructed, including 18 threat risk indicators and 14 vulnerability risk indicators to address the gaps in the existing research. The MEE model was employed to overcome the problem of incompatible indicator systems and provide stable and credible integrated measurement results. Finally, the whole-process public safety risk management scheme designed in this study can help to both provide a reference point for the Chinese enterprises and oversea contractors in market selection as well as improve ICP public safety risk management.