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Article
Publication date: 22 March 2021

Z.B. Xing, Xingchao Han, Hanbing Ke, Q.G. Zhang, Zhiping Zhang, Huijin Xu and Fuqiang Wang

A combination of highly conductive porous media and nanofluids is an efficient way for improving thermal performance of relevant applications. For precisely predicting the…

Abstract

Purpose

A combination of highly conductive porous media and nanofluids is an efficient way for improving thermal performance of relevant applications. For precisely predicting the flow and thermal transport of nanofluids in porous media, the purpose of this paper is to explore the inter-phase coupling numerical methods.

Design/methodology/approach

Based on the lattice Boltzmann (LB) method, this study combines the convective flow, non-equilibrium thermal transport and phase interactions of nanofluids in porous matrix and proposes a new multi-phase LB model. The micro-scale momentum and heat interactions are especially analyzed for nanoparticles, base fluid and solid matrix. A set of three-phase LB equations for the flow/thermal coupling of base fluid, nanoparticles and solid matrix is established.

Findings

Distributions of nanoparticles, velocities for nanoparticles and the base fluid, temperatures for three phases and interaction forces are analyzed in detail. Influences of parameters on the nanofluid convection in the porous matrix are examined. Thermal resistance of nanofluid convective transport in porous structures are comprehensively discussed with the models of multi-phases. Results show that the Rayleigh number and the Darcy number have significant influences on the convective characteristics. The result with the three-phase model is mildly larger than that with the local thermal non-equilibrium model.

Originality/value

This paper first creates the multi-phase theoretical model for the complex coupling process of nanofluids in porous structures, which is useful for researchers and technicians in fields of thermal science and computational fluid dynamics.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0961-5539

Keywords

Abstract

Details

Anti-Corrosion Methods and Materials, vol. 61 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 8 January 2020

Zhiping Zhu, Chun Shi, Yu Zhang and Zhifeng Liu

The purpose of this paper is to study the effects of Cl and direct stray current on the soil corrosion of three grounding grid materials.

Abstract

Purpose

The purpose of this paper is to study the effects of Cl and direct stray current on the soil corrosion of three grounding grid materials.

Design/methodology/approach

The electrochemical corrosion properties of three grounding grid materials, which include the Q235 steel, Q235 galvanized flat steel and copper, were measured by means of the weak polarization curve method and electrochemical impedance spectroscopy; the corrosion rate of specimens was calculated using the weight loss method; and the specimen surfaces were characterized using the scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction analysis.

Findings

Results showed that both factors, Cl and direct stray current, can accelerate the corrosion rate of grounding grid materials. The magnitude of DC stray current density affected the mass transfer type and response frequency of the anode and cathode reaction of grounding materials, while the Cl contents of the soil only affect the mass transfer rate of the electrode material from the electrochemical impedance spectroscopy diagrams. The electric field generated by the DC stray current caused Cl directed migration. The larger the DC stray current density, the greater the diffusion process and the greater the weight loss rate of the grounding grid materials that would have a logarithmic relationship with the Cl content at the same DC stray current density. The corrosion resistance of the three materials is copper > Q235 galvanized flat steel > Q235 flat steel.

Originality/value

The paper provides information regarding the relationship among Cl, direct stray current and corrosion of three grounding grid materials by means of electrochemical impedance spectroscopy. Meanwhile the weight loss rate is the logarithmic relationship with the Cl content, which is useful for understanding the corrosion mechanism of Q235 steel, Q235 galvanized flat steel and copper under the condition of Cl and direct stray current in soil.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 1 April 2006

Sun Zhiping, Shen Baoluo, Wang Jun, Liu Haohuai and Yang Hongshan

The relationship between Cr/C and properties of Fe‐C‐Cr high chromium white irons was studied by calculating the valence electron structure of austenite of Fe‐C‐Cr high…

Abstract

The relationship between Cr/C and properties of Fe‐C‐Cr high chromium white irons was studied by calculating the valence electron structure of austenite of Fe‐C‐Cr high chromium white irons with the empirical electron theory of solids and molecules (EET) and the equilibrium phase diagram of Fe‐C‐Cr system. Results show that the C‐Cr bond is the strongest bond of all bonds in alloying austenite in Fe‐C‐Cr high chromium white irons of industrial application and, thereby, causes partial aggregation of C‐Cr atomic groups. The weight of partial aggregation of C‐Cr atomic groups would be increased greatly and more austenite would be reserved to room temperature when Cr/>6. The Fe‐CCr high chromium white irons achieve best mechanical property when Cr/C=5.5‐6.5.

Details

Multidiscipline Modeling in Materials and Structures, vol. 2 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

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Article
Publication date: 17 March 2012

Zhiping Zhu, Hui Zhang, Linlin Jing, Shuhua Xiong and Zhenghui Tan

The purpose of this paper is to research the morphologies of the oxide films formed on the internal surfaces of water wall tubes in a 600 MW furnace at 300° while using…

Abstract

Purpose

The purpose of this paper is to research the morphologies of the oxide films formed on the internal surfaces of water wall tubes in a 600 MW furnace at 300° while using CPT, CT, AVT(R) and AVT(O) water chemistry. In these water chemistry conditions, a layer of oxide film spontaneously forms in the furnace wall which could prevent corrosions in boiler water directly contact with the inner tube and reduce the probability of tube perforation.

Design/methodology/approach

The different morphologies, specific functions and distribution in the oxide film were identified by electrochemical workstation, XRD, SEM and EDAX.

Findings

It is concluded that metal surface was rugged and had deep corrosion in CPT. Ions penetrated into the oxides of large particles with gaps and intergranular corrosion occurred in CT conditions. In AVT(R), the oxide film uniformly covered on the metal surface played a protective role, but could be easily washed away by solution. The oxide film formed in AVT(O) was similar to AVT(R), but the difference is that large solid particles of Fe2O3 cover the outermost oxide film, which prevents the oxide film from being taken away by the flowing solution. In consequence, the degree of corrosion sustained by the tube walls is lowest in the case of AVT(O).

Originality/value

The results can provide reference for reducing the high temperature corrosion of metal in the actual operation.

Details

Anti-Corrosion Methods and Materials, vol. 59 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 1 June 2004

Yang Daowu, Li Yuchun, Zhang Fang and Zhu Zhiping

In this study, electrochemical parameters were used to evaluate the inhibition effects of molybdate and silicate inhibitors in tap water. With the aid of “grey system”…

Abstract

In this study, electrochemical parameters were used to evaluate the inhibition effects of molybdate and silicate inhibitors in tap water. With the aid of “grey system” theory, we determine the inhibitive state model of such systems.

Details

Anti-Corrosion Methods and Materials, vol. 51 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 18 October 2018

Lei Wang, Haijun Xia, Yaowen Yang, Yiru Cai and Zhiping Qiu

The purpose of this paper is to propose a novel non-probabilistic reliability-based topology optimization (NRBTO) method for continuum structural design under interval…

Abstract

Purpose

The purpose of this paper is to propose a novel non-probabilistic reliability-based topology optimization (NRBTO) method for continuum structural design under interval uncertainties of load and material parameters based on the technology of 3D printing or additive manufacturing.

Design/methodology/approach

First, the uncertainty quantification analysis is accomplished by interval Taylor extension to determine boundary rules of concerned displacement responses. Based on the interval interference theory, a novel reliability index, named as the optimization feature distance, is then introduced to construct non-probabilistic reliability constraints. To circumvent convergence difficulties in solving large-scale variable optimization problems, the gradient-based method of moving asymptotes is also used, in which the sensitivity expressions of the present reliability measurements with respect to design variables are deduced by combination of the adjoint vector scheme and interval mathematics.

Findings

The main findings of this paper should lie in that new non-probabilistic reliability index, i.e. the optimization feature distance which is defined and further incorporated in continuum topology optimization issues. Besides, a novel concurrent design strategy under consideration of macro-micro integration is presented by using the developed RBTO methodology.

Originality/value

Uncertainty propagation analysis based on the interval Taylor extension method is conducted. Novel reliability index of the optimization feature distance is defined. Expressions of the adjoint vectors between interval bounds of displacement responses and the relative density are deduced. New NRBTO method subjected to continuum structures is developed and further solved by MMA algorithms.

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Article
Publication date: 5 September 2018

Linhao Ouyang, Zijian Zhang, Xiaoling Huang and Shi Xie

The purpose of this study is to restore the spatial distribution of overseas remittance businesses in Shantou during the 1940s. It explores various socioeconomic factors…

Abstract

Purpose

The purpose of this study is to restore the spatial distribution of overseas remittance businesses in Shantou during the 1940s. It explores various socioeconomic factors that influenced the concentration of local remittance business investment in real estate. By reconstructing the spatial distribution of remittance business activities in Shantou, this study hopes to lay a foundation for further analysis of the business strategies of Chaoshan merchants.

Design/methodology/approach

This research draws on information from the published Swatow Guide, archival sources and cadastral maps to identify the location of remittance enterprises and the native place and overseas networks of property owners.

Finding

This study reveals that the spatial distribution of the remittance enterprises was determined by the native place origins of local property owners, and that the inflow of overseas Chinese capital contributed to real estate development in Shantou.

Research limitations/implications

Despite the limited access to Chinese official archives, this paper manages to identify several building blocks and neighbors in Shantou for spatial analysis.

Practical implications

This study is the first attempt to use the geographical information system (GIS) method in Chinese urban history research and hopes to establish a larger historical database of Shantou as a sample for comparison.

Originality/value

This investigation advances the spatial study of urban history and overseas Chinese remittances in the maritime society of South China.

Details

Social Transformations in Chinese Societies, vol. 14 no. 2
Type: Research Article
ISSN: 1871-2673

Keywords

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Article
Publication date: 17 May 2013

Jing Fu, Feng Pei, Zhiping Zhu, Zhenghui Tan, Xu Tian, Rongjun Mao and Leijing Wang

The purpose of this paper is to study the influence of moisture on corrosion behaviour of steel ground rods in mildly desertified soil and the mechanism behind it.

Abstract

Purpose

The purpose of this paper is to study the influence of moisture on corrosion behaviour of steel ground rods in mildly desertified soil and the mechanism behind it.

Design/methodology/approach

The specimens were used for weight loss corrosion experiments and polarization scans were taken at different moisture levels. Specimen surfaces were characterized using a scanning electron microscope, energy dispersive spectrometer, and using X‐ray diffraction.

Findings

The results indicated that the moisture content of the soil influenced steel corrosion considerably. The maximum corrosion of 20G and Q235 galvanised steels occurred at 10 per cent and 12.5 per cent soil moisture, respectively. The corrosion products of 20G steel were mostly Fe2O3 and Fe3O4, whereas that of Q235 galvanised steel was Zn5(OH)8Cl2 · H2O.

Originality/value

The paper provides information regarding the relationship between moisture and corrosion of steel ground rods, which is useful for understanding the mechanism of soil corrosion. The research results can provide theoretical guidelines for preventing the corrosion of steel ground rods buried in mildly desertified soil.

Details

Anti-Corrosion Methods and Materials, vol. 60 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 4 February 2019

Manjet Kaur Mehar Singh

The purpose of this paper is to investigate and understand academic English language-related challenges in listening and speaking faced by English as a foreign language…

Abstract

Purpose

The purpose of this paper is to investigate and understand academic English language-related challenges in listening and speaking faced by English as a foreign language (EFL) international Master students enrolled in various taught Master programs in a Malaysian university from the viewpoint/lens of 16 lecturers teaching the students.

Design/methodology/approach

This qualitative research relied upon 16 in-depth one-to-one interview sessions with 16 lecturers teaching the taught Master programs at a higher education (HE) institution in Malaysia for data collection. Data collected were coded and categorized according to themes via qualitative analysis software, NVivo.

Findings

It was found that academic English language-related challenges in listening and speaking from the viewpoint of the 16 lecturers are such as lack of discipline content knowledge to communicate, lack of confidence in communicating orally, difficulty in understanding lectures and other oral activities in the classroom, and coping with differences in learning culture.

Research limitations/implications

This study suggests policies and programs to equip lecturers and university administrators to overcome the challenges faced by the students in their academic English language practices especially in listening and speaking to ensure meaningful academic adaptation in the current context.

Originality/value

The uniqueness of this study is that it is a retrospection of the lecturers teaching EFL and English as a second language (ESL) international Master students in taught Master programs in a Southeast Asian country. The focus of the retrospection is on academic English language-related challenges in listening and speaking faced by EFL international Master students who are currently pursuing their Master education at a HE institution in Malaysia.

Details

Journal of Applied Research in Higher Education, vol. 11 no. 2
Type: Research Article
ISSN: 2050-7003

Keywords

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