Guirong Yang, Wenming Song, Zibo Zhu, Ying Ma and Yuan Hao
The paper aims to study the effect of liquid flow velocity on corrosion behavior of 20# steel at initial stage under (CO2/aqueous solution) gas–liquid two-phase plug flow…
Abstract
Purpose
The paper aims to study the effect of liquid flow velocity on corrosion behavior of 20# steel at initial stage under (CO2/aqueous solution) gas–liquid two-phase plug flow conditions.
Design/methodology/approach
Weight loss, scanning electron microscopy, energy-dispersive X-ray spectroscopy and XPS methods were used in this study.
Findings
The corrosion rate increased with the increasing liquid flow velocity at any different corrosion time. The corrosion rate decreased with the extension of corrosion time at the same liquid flow velocity. There was no continuous corrosion products film on the whole pipe wall at any different corrosion time. The macroscopic brown-yellow corrosion products on the pipe wall surface decreased with the increasing liquid flow velocity and the loose floccus corrosion products decreased gradually until these products were transformed into un-continuous needle-like dense products with the increasing liquid velocity. The main elements among the products film were Fe, C and O, and the main phases of products film on the pipe wall were Fe3C, FeCO3, FeOOH and Fe3O4. When the corrosion time was 1 h under different liquid–velocity condition, the thickness of local corrosion products film was from 3.5 to 3.8 µm.
Originality/value
The ion mass transfer model of corrosion process in pipe was put forward under gas–liquid two-phase plug flow condition. The total thickness of diffusion sublayer and turbulence sublayer decreased as well as the turbulence propagation coefficient increased with the increasing liquid velocity, which led to the increasing velocity of ion transfer during corrosion process. This was the fundamental reason for the increase of corrosion rate with the increasing liquid velocity.
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Guirong Yang, Wenming Song, Fuqiang Wang, Ying Ma and Yuan Hao
This paper aims to investigate the corrosion rate, surface morphology and composition of corrosion products of 20# seamless steel in aqueous CO2 solution under stratified…
Abstract
Purpose
This paper aims to investigate the corrosion rate, surface morphology and composition of corrosion products of 20# seamless steel in aqueous CO2 solution under stratified gas-liquid two-phase flow condition. The development of a corrosion products layer has also been discussed.
Design/methodology/approach
The following methods were used: weight loss method, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction.
Findings
The corrosion rate curve presents an irregular zigzag change trend with a gradual increase in time. The peak value of the corrosion rate appears when the corrosion time is 4 h and 8 h. The corrosion products layer is composed of two sub-layers: the inner dense layer that is about 6 µm thick and the outer loose layer that is about 9 µm thick when the corrosion time is 8 h. The main corrosion product are FeCO3 and Fe2O3.
Originality/value
The atomic ratio of Fe/C/O is relatively stable for the inner dense layer, but changes in thickness for the outer loose layer. There is a densification stage after a loose corrosion products layer forms, and it is periodic.
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Guirong Yang, Zhaoxia Pan, Zhenghai Zhang, Wenming Song, Ying Ma and Yuan Hao
This study aims to investigate the initial corrosion behavior in aqueous solution of 20# seamless steel under (CO2/aqueous solution) gas–liquid two-phase stratified flow…
Abstract
Purpose
This study aims to investigate the initial corrosion behavior in aqueous solution of 20# seamless steel under (CO2/aqueous solution) gas–liquid two-phase stratified flow conditions.
Design/methodology/approach
The initial corrosion behavior was studied through the weight loss methods, scanning electron microscopy with energy-dispersive x-ray spectroscopy and x-ray diffraction.
Findings
The corrosion rate of 20# steel obviously increases with the increasing gas pressure at different corrosion time when the CO2 pressure is less than 0.11 MPa, and the increase of corrosion rate tends to be steady when the pressure exceeds 0.11 MPa. With the increase of CO2 pressure, the corrosion products changed from flocculent to acicular, granular and scaly. A four-stage model for the growth of the corrosion product layer was proposed, namely, the diffusion reaction stage, the local film formation stage, the complete film formation stage and the densification stage of the product film.
Originality/value
A four-stage model for the growth of the corrosion product layer on the pipe wall surface under this condition was proposed, namely, the diffusion reaction stage, the local film formation stage, the complete film formation stage and the densification stage of the product film. The growing process and densification mechanism of corrosion products layer were discussed.
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Lan Song, Yang Zhao, Yaoming Zhou and Haifei Xiang
The purpose of this paper is to analyze and figure out the temperature field and thermal stress field with the calculation model of thermal insulation material and composite…
Abstract
Purpose
The purpose of this paper is to analyze and figure out the temperature field and thermal stress field with the calculation model of thermal insulation material and composite material.
Design/methodology/approach
The paper adopted the three-dimensional finite element algorithm.
Findings
The simulated results showed great shearing strength between the chipset and the printed circuit board. The position of chip exerts great influence on the distribution of temperature field and thermal stress field of circuit board. The reasonable distribution of chip will effectively reduce the temperature extremum and stress extremum of circuit board.
Originality/value
The paper analyzes and presents a discussion of the problems relating to the density of electronic packaging. The analysis process and the method of the paper provide essential help in resolving electronic device heat problems.
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Xiaofang Ma, Wenming Wang, Gaoguang Zhou and Jun Chen
This study aims to take advantage of the unprecedented anti-corruption campaign launched in China in December 2012 and examine the effect of improved public governance on…
Abstract
Purpose
This study aims to take advantage of the unprecedented anti-corruption campaign launched in China in December 2012 and examine the effect of improved public governance on tunneling.
Design/methodology/approach
This study uses a sample of Shanghai and Shenzhen Stock Exchange listed companies from 2010 to 2014 and conduct regression analyses to investigate the effect of improved public governance attributed to the anti-corruption campaign on tunneling.
Findings
This study finds that the level of tunneling decreased significantly after the anti-corruption campaign, suggesting that increased public governance effectively curbs tunneling. Cross-sectional results show that this mitigating effect is more pronounced for non-SOE firms, especially non-SOE firms with political connections, firms audited by non-Big 8 auditors, firms with a large divergence between control rights and cash flow rights and firms located in areas with lower marketization.
Practical implications
This study highlights the importance of anti-corruption initiatives in improving public governance and in turn reducing tunneling. This study provides important implications for many other emerging economies to improve public governance.
Originality/value
This study contributes to the literature on the role of public governance in constraining corporate agency problems and advances the understanding of the economic consequences of China's anti-corruption campaign in the context of tunneling.
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Xuhui Ye, Gongping Wu, Fei Fan, XiangYang Peng and Ke Wang
An accurate detection of overhead ground wire under open surroundings with varying illumination is the premise of reliable line grasping with the off-line arm when the inspection…
Abstract
Purpose
An accurate detection of overhead ground wire under open surroundings with varying illumination is the premise of reliable line grasping with the off-line arm when the inspection robot cross obstacle automatically. This paper aims to propose an improved approach which is called adaptive homomorphic filter and supervised learning (AHSL) for overhead ground wire detection.
Design/methodology/approach
First, to decrease the influence of the varying illumination caused by the open work environment of the inspection robot, the adaptive homomorphic filter is introduced to compensation the changing illumination. Second, to represent ground wire more effectively and to extract more powerful and discriminative information for building a binary classifier, the global and local features fusion method followed by supervised learning method support vector machine is proposed.
Findings
Experiment results on two self-built testing data sets A and B which contain relative older ground wires and relative newer ground wire and on the field ground wires show that the use of the adaptive homomorphic filter and global and local feature fusion method can improve the detection accuracy of the ground wire effectively. The result of the proposed method lays a solid foundation for inspection robot grasping the ground wire by visual servo.
Originality/value
This method AHSL has achieved 80.8 per cent detection accuracy on data set A which contains relative older ground wires and 85.3 per cent detection accuracy on data set B which contains relative newer ground wires, and the field experiment shows that the robot can detect the ground wire accurately. The performance achieved by proposed method is the state of the art under open environment with varying illumination.
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Jingen Zhou, Shu-Ling (Peggy) Chen and Wenming (Wendy) Shi
The cruise industry has witnessed steady growth, with passenger volume increasing from 17.8 million in 2009 to 30 million in 2019. In the context of global competition and an…
Abstract
Purpose
The cruise industry has witnessed steady growth, with passenger volume increasing from 17.8 million in 2009 to 30 million in 2019. In the context of global competition and an uncertain business environment, competition in business has changed dramatically from battles of “firm versus firm” to “supply chain versus supply chain”. Hence, the purpose of this paper is to understand the cruise industry from a chain perspective, which has not drawn widespread research attention.
Design/methodology/approach
This paper brings together the insights, opinions, concepts and frameworks from a literature review of different disciplines (maritime shipping, tourism management, logistics management, operations management and supply chain management) and analysis results from 22 semi-structured interviews to make an early attempt to conceptualise the cruise supply chain (CSC).
Findings
The cruise supply chain is elaborated on the process, the role of each entity and its characteristics by comparing with the maritime supply chain and tourism supply chain. Based on the understanding of the CSC, two specific characteristics of the Chinese CSC are examined, which need further investigation.
Originality/value
The CSC is articulated with detailed processes and characteristics based on the literature review and empirical study. The findings of this paper not only advance the knowledge of the supply chain in the cruise industry but also highlight the importance of further research on the CSC.
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Liu Wenming, Sheng Tianyuan and Kong Dejun
The purpose of this paper is to provide an experimental basis for studying the effects of laser remelting on the surface modification of arc-sprayed Al coating.
Abstract
Purpose
The purpose of this paper is to provide an experimental basis for studying the effects of laser remelting on the surface modification of arc-sprayed Al coating.
Design/methodology/approach
A layer of arc-sprayed Al coating on S355 steel was remelted with a CO2 laser, and the surface-interface morphologies, compositions of chemical elements and phases of Al coating were analyzed with scanning electron microscopy, energy disperse spectroscopy and X-ray diffraction, respectively. The effects of laser remelting on compositions of chemical elements and bonding performance of Al coatings were discussed.
Findings
The result shows that there are some pores existing on the Al coating surface after arc spraying, and the combination mode of coating interface is primarily composed of mechanical bonding. The pores on the Al coating reduce after laser remelting, which improves the compact performance, and the mechanical binding mode by arc spraying is changed into metallurgical bonding. The Fe and Al atoms at the coating interface are distributed with gradient, and the stratified enrichment is evident, which improves binding performance of the Al coating. The Al coating exhibits general corrosion before laser remelting and local corrosion after laser remelting, which improves the corrosion resistance of Al coating.
Originality/value
The arc-sprayed Al coating is remelted by CO2 laser, improving its microstructures and bonding mode with the substrate.
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Yishan Liu, Wenming Cao and Guitao Cao
Session-based recommendation aims to predict the user's next preference based on the user's recent activities. Although most existing studies consider the global characteristics…
Abstract
Purpose
Session-based recommendation aims to predict the user's next preference based on the user's recent activities. Although most existing studies consider the global characteristics of items, they only learn the global characteristics of items based on a single connection relationship, which cannot fully capture the complex transformation relationship between items. We believe that multiple relationships between items in learning sessions can improve the performance of session recommendation tasks and the scalability of recommendation models. At the same time, high-quality global features of the item help to explore the potential common preferences of users.
Design/methodology/approach
This work proposes a session-based recommendation method with a multi-relation global context–enhanced network to capture this global transition relationship. Specifically, we construct a multi-relation global item graph based on a group of sessions, use a graded attention mechanism to learn different types of connection relations independently and obtain the global feature of the item according to the multi-relation weight.
Findings
We did related experiments on three benchmark datasets. The experimental results show that our proposed model is superior to the existing state-of-the-art methods, which verifies the effectiveness of our model.
Originality/value
First, we construct a multi-relation global item graph to learn the complex transition relations of the global context of the item and effectively mine the potential association of items between different sessions. Second, our model effectively improves the scalability of the model by obtaining high-quality item global features and enables some previously unconsidered items to make it onto the candidate list.
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John Chi‐kin Lee, Daoyong Ding and Huan Song
The purpose of this paper is to discuss recent developments in school developmental supervisory evaluation in the Pudong New Area of Shanghai in the Chinese Mainland.
Abstract
Purpose
The purpose of this paper is to discuss recent developments in school developmental supervisory evaluation in the Pudong New Area of Shanghai in the Chinese Mainland.
Design/methodology/approach
The main research approach is qualitative, using documentary analysis and interviews of an inspector, principals and teachers from two primary schools.
Findings
There were perceived positive and negative impacts of school supervision and evaluation.
Originality/value
The paper highlights the implications for fostering a shared school‐government community of school supervision and evaluation, promoting a dynamic approach for addressing contextual differences as well as achieving better coherence among educational reform, supervision and evaluation policies.