Search results

1 – 10 of 42
Per page
102050
Citations:
Loading...
Access Restricted. View access options
Article
Publication date: 9 August 2019

Li-Xiang Wang, Da-Hai Xia, Shi-Zhe Song, Yashar Behnamian and Likun Xu

This paper aims to quantify atmospheric corrosion by image analyses. The corrosion extent, form and distribution of corrosion product on Q235B and T91 steels exposed to a Zhoushan…

149

Abstract

Purpose

This paper aims to quantify atmospheric corrosion by image analyses. The corrosion extent, form and distribution of corrosion product on Q235B and T91 steels exposed to a Zhoushan marine atmosphere over one year are characterized by image analysis.

Design/methodology/approach

Image analysis of corrosion images were achieved using the gray value, wavelet analysis and fuzzy Kolmogorov–Sinai (K–S) entropy.

Findings

As corrosion becomes extensive, the gray value of corrosion images decreases, and the energy value of nine subimages after wavelength decomposition decreases. Fuzzy K–S entropy increases as localized corrosion propagates but decreases as uniform corrosion spreads.

Originality/value

The methods proposed in this work open a new way for fast corrosion evaluation of metallic materials exposed to atmospheric conditions.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

Access Restricted. View access options
Article
Publication date: 6 March 2017

Ru Zhao, Da-Hai Xia, Shi-Zhe Song and Wenbin Hu

This paper aims to investigate the stress corrosion cracking (SCC) process of sensitized 304 stainless steel during the slow strain rate test by using the electrochemical noise…

144

Abstract

Purpose

This paper aims to investigate the stress corrosion cracking (SCC) process of sensitized 304 stainless steel during the slow strain rate test by using the electrochemical noise (EN) technique.

Design/methodology/approach

EN data are interpreted based on chaos and wavelet analyses, and correlation dimension and wavelet energy distribution are used as indicators for SCC process identification.

Findings

Experimental results reveal that the corrosion potential abruptly decreases from 180 to 100 mV at 6,300 s and the current increases from 10 to 100 nA accordingly, which is attributed to passive film breakdown and crack initiation. Chaos and wavelet analyses results reveal that, as crack initiates, the correlation dimensions increase from 1.2 to 1.9, and the corresponding distribution frequencies of maximum relative wavelet energy change from high frequency to low frequency.

Originality/value

SCC is monitored in lab, and crack initiation and propagation are identified by chaos and wavelet analyses. This work lays the foundation for SCC detection in field using EN.

Details

Anti-Corrosion Methods and Materials, vol. 64 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

Access Restricted. View access options
Article
Publication date: 6 November 2009

Ya Nan Luo, Shi Zhe Song, Wei Xian Jin and Lei Han

The purpose of this paper is to research electrochemical testing technology as applied to in field corrosion evaluation of metallic materials and to study the corrosion behaviors…

396

Abstract

Purpose

The purpose of this paper is to research electrochemical testing technology as applied to in field corrosion evaluation of metallic materials and to study the corrosion behaviors of the materials exposed in different marine regions.

Design/methodology/approach

The electrode systems for in field electrochemical evaluation of metallic samples are designed and applied to monitor two types of carbon steel samples exposed both in the submerged zone and the tidal zone at a marine corrosion test station. Corrosion potential monitoring, potentiostatic square wave, electrochemical impedance spectroscopy, and electrochemical noise methods are used in the test.

Findings

It is confirmed that the electrode systems could be used for electrochemical measurement of metallic samples during exposure in the submerged zone and the tidal zone of a marine corrosion test station for long‐term test durations. The electrochemical measuring results reflect the changes and differences of the samples' corrosion behavior during exposure in different regions and they respond directly to the influence of marine environmental factors on the corrosion behaviors, especially the influence of temperature.

Originality/value

In this paper, lots of consecutive and dynamic corrosion information is obtained from field exposures. The findings provide a foundation upon which to investigate and forecast the corrosion behaviors of materials in marine environments.

Details

Anti-Corrosion Methods and Materials, vol. 56 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Access Restricted. View access options
Article
Publication date: 5 October 2023

Kaikai Shi, Hanan Lu, Xizhen Song, Tianyu Pan, Zhe Yang, Jian Zhang and Qiushi Li

In a boundary layer ingestion (BLI) propulsion system, the fan operates continuously under distorted inflow conditions, leading to an increment of aerodynamic loss and in turn…

235

Abstract

Purpose

In a boundary layer ingestion (BLI) propulsion system, the fan operates continuously under distorted inflow conditions, leading to an increment of aerodynamic loss and in turn impacting the potential fuel burn reduction of the aircraft. Usually, in the preliminary design stage of a BLI propulsion system, it is essential to assess the impact of fuselage boundary layer fluids on fan aerodynamic performances under various flight conditions. However, the hub region flow loss is one of the major loss sources in a fan and would greatly influence the fan performances. Moreover, the inflow distortion also results in a complex and highly nonlinear mapping relation between loss and local physical parameters. It will diminish the prediction accuracy of the commonly used low-fidelity computational approaches which often incorporate traditional physics-based loss models, reducing the reliability of these approaches in evaluating fan performances. Meanwhile, the high-fidelity full-annulus unsteady Reynolds-averaged Navier–Stokes (URANS) approach, even though it can give rather accurate loss predictions, is extremely time-consuming. This study aims to develop a fast and accurate hub loss prediction method for a BLI fan under distorted inflow conditions.

Design/methodology/approach

This paper develops a data-driven hub loss prediction method for a BLI fan under distorted inflows. To improve the prediction accuracy and applicability, physical understandings of hub flow features are integrated into the modeling process. Then, the key physical parameters related to flow loss are screened by conducting a sensitivity analysis of influencing parameters. Next, a quasi-steady assumption of flow is made to generate a training sample database, reducing the computational time by acquiring one single sample from the highly time-consuming full-annulus URANS approach to a cost-efficient single-blade-passage approach. Finally, a radial basis function neural network is used to establish a surrogate model that correlates the input parameters and the output loss.

Findings

The data-driven hub loss model shows higher prediction accuracy than the traditional physics-based loss models. It can accurately capture the circumferentially and radially nonuniform variation trends of the losses and the associated absolute magnitudes in a BLI fan under different blade load, inlet distortion intensity and rotating speed conditions. Compared with the high-fidelity full-annulus URANS results, the averaged relative prediction errors of the data-driven hub loss model are kept less than 10%.

Originality/value

The originality of this paper lies in developing a new method for predicting flow loss in a BLI fan rotor blade hub region. This method offers higher prediction accuracy than the traditional loss models and lower computational time cost than the full-annulus URANS approach, which could realize fast evaluations of fan aerodynamic performances and provide technical support for designing high-performance BLI fans.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 34 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

Access Restricted. View access options
Book part
Publication date: 18 July 2018

Mengwei Tu

Abstract

Details

Education, Migration and Family Relations between China and the UK: The Transnational One-Child Generation
Type: Book
ISBN: 978-1-78714-673-0

Access Restricted. View access options
Article
Publication date: 11 July 2023

Yuze Shang, Fei Liu, Ping Qin, Zhizhong Guo and Zhe Li

The goal of this research is to develop a dynamic step path planning algorithm based on the rapidly exploring random tree (RRT) algorithm that combines Q-learning with the…

268

Abstract

Purpose

The goal of this research is to develop a dynamic step path planning algorithm based on the rapidly exploring random tree (RRT) algorithm that combines Q-learning with the Gaussian distribution of obstacles. A route for autonomous vehicles may be swiftly created using this algorithm.

Design/methodology/approach

The path planning issue is divided into three key steps by the authors. First, the tree expansion is sped up by the dynamic step size using a combination of Q-learning and the Gaussian distribution of obstacles. The invalid nodes are then removed from the initially created pathways using bidirectional pruning. B-splines are then employed to smooth the predicted pathways.

Findings

The algorithm is validated using simulations on straight and curved highways, respectively. The results show that the approach can provide a smooth, safe route that complies with vehicle motion laws.

Originality/value

An improved RRT algorithm based on Q-learning and obstacle Gaussian distribution (QGD-RRT) is proposed for the path planning of self-driving vehicles. Unlike previous methods, the authors use Q-learning to steer the tree's development direction. After that, the step size is dynamically altered following the density of the obstacle distribution to produce the initial path rapidly and cut down on planning time even further. In the aim to provide a smooth and secure path that complies with the vehicle kinematic and dynamical restrictions, the path is lastly optimized using an enhanced bidirectional pruning technique.

Details

Engineering Computations, vol. 40 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Access Restricted. View access options
Article
Publication date: 28 September 2020

Xiaobin Feng, Xiaoshu Ma, Zhe Shi and Xuebing Peng

To address the gap of divergent conclusions on the impact of knowledge search (KS) on performance, this paper aims to discuss the nonlinear relationships between KS and reverse…

732

Abstract

Purpose

To address the gap of divergent conclusions on the impact of knowledge search (KS) on performance, this paper aims to discuss the nonlinear relationships between KS and reverse internationalization enterprise (RIE) performance, and the co-moderation of causation and effectuation (C&E) on KS–performance.

Design/methodology/approach

The proposed theoretical model is developed by integrating the theory of knowledge-based view and decision rationality theory. The empirical study is based on survey data collected from 245 RIEs of the Yangtze River Delta and Pearl River Delta regions in China. Hierarchical multiple regression and the appropriate U-test method are used to test the hypotheses.

Findings

Empirical results suggest that both focused and multi-focus searches have inverted U-shaped effects on RIE performance. Furthermore, causation weakens the curvilinear effect between multi-focus search and RIE performance, whereas effectuation strengthens the curvilinear effect but weakens the inverted U-shaped relationship between focused search and RIE performance. Results also indicate that the integration of C&E positively moderates the relationship between focused or multi-focus searches and RIE performance.

Originality/value

Findings reveal the nonlinear effects of focused and multi-focus searches on RIE performance and clarify the dispute over the mechanism of KS on performance by proposing the different moderating role of C&E. Moreover, this research provides deeper insight into contingency mechanisms between KS and performance by integrating the co-moderating role of C&E in RIEs.

Details

Journal of Knowledge Management, vol. 25 no. 5
Type: Research Article
ISSN: 1367-3270

Keywords

Access Restricted. View access options
Article
Publication date: 19 March 2021

Chengxi Zhang, Jin Wu, Yulong Huang, Yu Jiang, Ming-zhe Dai and Mingjiang Wang

Recent spacecraft attitude control systems tend to use wireless communication for cost-saving and distributed mission purposes while encountering limited communication resources…

223

Abstract

Purpose

Recent spacecraft attitude control systems tend to use wireless communication for cost-saving and distributed mission purposes while encountering limited communication resources and data exposure issues. This paper aims to study the attitude control problem with low communication frequency under the sampled-data.

Design/methodology/approach

The authors propose constructive control system structures based on quantization and event-triggered methods for intra-spacecraft and multi-spacecraft systems, and they also provide potential solutions to shield the control system's data security. The proposed control architectures can effectively save communication resources for both intra-spacecraft and multi-spacecraft systems.

Findings

The proposed control architectures no longer require sensors with trigger-ing mechanism and can achieve distributed control schemes. This paper also provides proposals of employing the public key encryption to secure the data in control-loop, which is transmitted by the event-triggered control mechanism.

Practical implications

Spacecraft attempts to use wireless communication, yet the attitude control system does not follow up promptly to accommodate these variations. Compared with existing approaches, the proposed control structures can save communication resources of control-loop in multi-sections effectively, and systematically, by rationally configuring the location of quantization and event-triggered mechanisms.

Originality/value

This paper presents several new control schemes and a necessary condition for the employment of encryption algorithms for control systems based on event-based communication.

Details

Aircraft Engineering and Aerospace Technology, vol. 93 no. 2
Type: Research Article
ISSN: 1748-8842

Keywords

Available. Open Access. Open Access
Article
Publication date: 2 October 2017

Beibei Xiong, Yongli Li, Ernesto D.R. Santibanez Gonzalez and Malin Song

The purpose of this paper is to measure Chinese industries’ eco-efficiency during 2006-2013. The Chinese industry attained rapid achievement in recent decades, but meanwhile…

1535

Abstract

Purpose

The purpose of this paper is to measure Chinese industries’ eco-efficiency during 2006-2013. The Chinese industry attained rapid achievement in recent decades, but meanwhile, overconsumption of energy and environmental pollution have become serious problems. To solve these problems, many research studies used the data envelopment analysis (DEA) to measure the Chinese industry’s eco-efficiency. However, because the target set by these works is usually the furthest one for a province to be efficient, it may hardly be accepted by any province.

Design/methodology/approach

This paper builds a new “closest target method” based on an additive DEA model considering the undesirable outputs. This method is a mixed-integer programming problem which can measure the ecological efficiency of provinces and more importantly guide the province to perform efficiently with minimum effort.

Findings

The results show that the eco-efficiency of Chinese provinces increased at the average level, but the deviations remained at a larger value. Compared to the “furthest” target methods, the targets by the approach proposed by this study are more acceptable for a province to improve its performance on both economy and environment counts.

Originality/value

This study is the first attempt to introduce the closest targets concept to measure the eco-efficiency and set the target for each provincial industry in China.

Details

International Journal of Climate Change Strategies and Management, vol. 9 no. 5
Type: Research Article
ISSN: 1756-8692

Keywords

Access Restricted. View access options
Article
Publication date: 6 June 2016

Check Teck Foo

The purpose of this paper in the editorial review of manuscripts to highlight the emergent aspects of original thinking that provide new perspectives on issues central to…

241

Abstract

Purpose

The purpose of this paper in the editorial review of manuscripts to highlight the emergent aspects of original thinking that provide new perspectives on issues central to management.

Design/methodology/approach

A synoptic perspective of a very broad range of topics covered in research by scholars is provided: education, corporate value, quality, corporate social responsibility, risk behavior, managing reputation, expatriation, growth and creativity. In this particular review, the editor emphasizes those facets of the paper that shed original, new light on management. Also, the areas where research provides a theoretical basis for consulting or managerial practice are highlighted to illustrate how research can be of practical relevance.

Findings

Some of the insights gained clearly indicate the importance of research. For example, tighter or more rigorous governmental regulations on food quality are unlikely to contribute to the enhancement of firms’ capability in improving food quality. The government needs to do much more than only regulate. Then, there is empirical reaffirmation that guan-xi with government matters: better the relationships, the higher corporate value but only if the firm is in private hands, not for state-owned enterprises (SOEs). Then, the Chinese local firms’ nexus with foreign, and international corporations influences their corporate social performance. Even more fascinating, a bank’s risk behavior is dependent on the structural composition of the board of directors. Indeed, research shows that a gender mix in fact lowers the propensity toward taking a high risk. Then, through reflecting upon their deep researches, the authors derive a theoretic framework for coping with reputation loss following a financial restatement. Here, authors showed SOEs to suffer much more in the event of restatement than the privately owned enterprises. Then, in a piece of innovative research of expatriation, authors relate a spectrum of the Chinese cultural values to performance. In a cross-country (civilization) study, the research motivation is: Whether SMEs in China, India and Pakistan are confronting the same environmental challenges? As expected, the answer would be yes in some aspects and no in others. This a significant finding, as the Chinese are raised on a milieu of suppressing one’s emotions: emotional expressiveness can contribute to creativity!

Originality/value

In this paper, the editor highlights some aspects on the original thinking of the authors within this issue of Chinese Management Studies. Also, the editor highlights on how research contained herein is contributing to managerial (consulting) practice.

1 – 10 of 42
Per page
102050