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Article
Publication date: 13 June 2019

Rui Zhang, Lei Zhao, Dan Xie, Jinlong Song, Wendong Zhang, Lihu Pan and Yanhua Zhang

This study aims to simulate and test the performance of a transmitting and receiving capacitive micro-machined ultrasonic transducer (CMUT). Aimed at detecting demand of…

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Abstract

Purpose

This study aims to simulate and test the performance of a transmitting and receiving capacitive micro-machined ultrasonic transducer (CMUT). Aimed at detecting demand of the CMUT, a matched integrated adjustment circuit was designed through analyzing processing methods of transducer’s weak echo signal.

Design/methodology/approach

Based on the analysis of CMUT array structure and work principle, the CMUT units are designed and the dynamic performance analysis of SIMULINK is given according to the demand of underwater detecting. A transceiver isolation circuit is used to make transmission mode and receiving mode separate. A detection circuit is designed based on the transimpedance amplifier to achieve extraction of high-frequency and weak signal.

Findings

Through experimentation, the effectiveness of the CMUT performance simulation and the transceiver integrated adjustment circuit were verified. In addition, the test showed that CMUT with 400 kHz frequency has wider bandwidth and better dynamic characteristics than other similar transducers.

Originality/value

This paper provides a theoretical basis and design reference for the development and application of CMUT technology.

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Article
Publication date: 1 September 2021

Yi Zhang Rui Huang

With the booming development of computer, optical and sensing technologies and cybernetics, the technical research in unmanned vehicle has been advanced to a new era. This…

Abstract

Purpose

With the booming development of computer, optical and sensing technologies and cybernetics, the technical research in unmanned vehicle has been advanced to a new era. This trend arouses great interest in simultaneous localization and mapping (SLAM). Especially, light detection and ranging (Lidar)-based SLAM system has the characteristics of high measuring accuracy and insensitivity to illumination conditions, which has been widely used in industry. However, SLAM has some intractable problems, including degradation under less structured or uncontrived environment. To solve this problem, this paper aims to propose an adaptive scheme with dynamic threshold to mitigate degradation.

Design/methodology/approach

We propose an adaptive strategy with a dynamic module is proposed to overcome degradation of point cloud. Besides, a distortion correction process is presented in the local map to reduce the impact of noise in the iterative optimization process. Our solution ensures adaptability to environmental changes.

Findings

Experimental results on both public data set and field tests demonstrated that the algorithm is robust and self-adaptive, which achieved higher localization accuracy and lower mapping error compared with existing methods.

Originality/value

Unlike other popular algorithms, we do not rely on multi-sensor fusion to improve the localization accuracy. Instead, the pure Lidar-based method with dynamic threshold and distortion correction module indeed improved the accuracy and robustness in localization results.

Details

Sensor Review, vol. 41 no. 4
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 19 June 2017

Liubov Skavronskaya, Noel Scott, Brent Moyle, Dung Le, Arghavan Hadinejad, Rui Zhang, Sarah Gardiner, Alexandra Coghlan and Aishath Shakeela

This review aims to discuss concepts and theories from cognitive psychology, identifies tourism studies applying them and discusses key areas for future research. The…

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Abstract

Purpose

This review aims to discuss concepts and theories from cognitive psychology, identifies tourism studies applying them and discusses key areas for future research. The paper aims to demonstrate the usefulness of cognitive psychology for understanding why tourists and particularly pleasure travellers demonstrate the behaviour they exhibit.

Design/methodology/approach

The paper reviews 165 papers from the cognitive psychology and literature regarding pleasure travel related to consciousness, mindfulness, flow, retrospection, prospection, attention, schema and memory, feelings and emotions. The papers are chosen to demonstrate the state of the art of the literature and provide guidance on how these concepts are vital for further research.

Findings

The paper demonstrates that research has favoured a behaviourist rather than cognitive approach to the study of hedonic travel. Cognitive psychology can help to understand the mental processes connecting perception of stimuli with behaviour. Numerous examples are provided: top-down and bottom-up attention processes help to understand advertising effectiveness, theories of consciousness and memory processes help to distinguish between lived and recalled experience, cognitive appraisal theory predicts the emotion elicited based on a small number of appraisal dimensions such as surprise and goals, knowledge of the mental organisation of autobiographical memory and schema support understanding of destination image formation and change and the effect of storytelling on decision-making, reconstructive bias in prospection or retrospection about a holiday inform the study of pleasurable experience. These findings indicate need for further cognitive psychology research in tourism generally and studies of holiday travel experiences.

Research limitations/implications

This review is limited to cognitive psychology and excludes psychoanalytic studies.

Practical implications

Cognitive psychology provides insight into key areas of practical importance. In general, the use of a cognitive approach allows further understanding of leisure tourists’ behaviour. The concept of attention is vital to understand destination advertising effectiveness, biases in memory process help to understand visitor satisfaction and experience design and so on. Use of cognitive psychology theory will lead to better practical outcomes for tourists seeking pleasurable experiences and destination managers.

Originality value

This is the first review that examines the application of concepts from cognitive psychology to the study of leisure tourism in particular. The concepts studied are also applicable to study of travellers generally.

Details

Tourism Review, vol. 72 no. 2
Type: Research Article
ISSN: 1660-5373

Keywords

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Article
Publication date: 14 March 2016

Rui Zhang and Binjie Xin

The purpose of this paper is introducing the image processing technology used for fabric analysis, which has the advantages of objective, digital and quick response.

Abstract

Purpose

The purpose of this paper is introducing the image processing technology used for fabric analysis, which has the advantages of objective, digital and quick response.

Design/methodology/approach

This paper briefly describes the key process and module of some typical automatic recognition systems for fabric analysis presented by previous researchers; the related methods and algorithms used for the texture and pattern identification are also introduced.

Findings

Compared with the traditional subjective method, the image processing technology method has been proved to be rapid, accurate and reliable for quality control.

Originality/value

The future trends and limitations in the field of weave pattern recognition for woven fabrics have been summarized at the end of this paper.

Details

Research Journal of Textile and Apparel, vol. 20 no. 1
Type: Research Article
ISSN: 1560-6074

Keywords

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Article
Publication date: 16 October 2018

Khurram Ashfaq and Zhang Rui

This study aims to revisit the corporate social and environmental disclosure (CSED) practices of Pakistani companies using unique CSED index which measures the CSED…

Abstract

Purpose

This study aims to revisit the corporate social and environmental disclosure (CSED) practices of Pakistani companies using unique CSED index which measures the CSED through three dimensions such as theme, news type and nature of information. In addition, the effect of board composition, ownership structure and corporate characteristics on CSED was tested through performing multiple regression analysis.

Design/methodology/approach

For this purpose, data were collected from annual reports of top 120 companies’ selected based on market capitalization for three years period of 2013-2015.

Findings

Based on the descriptive statistics, the results found that overall level of CSED in Pakistan is moderate. However considering CSED using three dimensions, the results demonstrate that highest level of disclosure on the basis of theme is reported in terms of human resource category as compared to other categories where, as in terms of news type and nature of information, analysis shows that companies in Pakistan feel resistant to disclose bad news, monetary and non-monetary aspect of CSED information. Using multiple regression analysis, the results found that all the variables have hypothesized relationship with CSED except government and institutional ownership. The variables such as chairman as non-executive director, board diversity, appointment of independent director as audit committee chairman, CSR committee, industry type and firm size are found to have significant influence on the CSED practices in Pakistan.

Research limitations/implications

These results imply that the CSED phenomenon is still lacking behind. Under individual categories of CSED, descriptive statistics found that environment is still not a matter of concern for companies operating in Pakistan. In addition, the results demonstrate that CSED practices are only performed by very few companies in Pakistan based on standard deviation. In addition, appointment of non-executive and independent director as chairman of board and audit committee and representation of foreigners on the board should be encouraged in order to improve CSED practices in Pakistan.

Originality/value

This study contributes to the existing literature in developing country like Pakistan through using unique CSED index and also making comparison of financial versus non-financial sectors. The author suggests that regulatory authorities in Pakistan must take reasonable steps to make the company’s operations environment-friendly.

Details

Social Responsibility Journal, vol. 15 no. 1
Type: Research Article
ISSN: 1747-1117

Keywords

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Article
Publication date: 10 September 2020

Zhiming Zhao, Rui Zhang, Feng Ji and Xiaoyang Yuan

High power and speed are new demands for rotating machinery which needs the journal bearings with high dynamic characteristics. The critical speed of the rotor-bearing…

Abstract

Purpose

High power and speed are new demands for rotating machinery which needs the journal bearings with high dynamic characteristics. The critical speed of the rotor-bearing system is one of the most significant parameters to evaluate the dynamic characteristics. This paper aims to investigate the theoretical and experimental analysis of a rotor system supported by large diameter elliptical bearings.

Design/methodology/approach

To obtain the theoretical and experimental support for rotor-bearing system design, dynamic characteristics theoretical analysis based on the finite difference method is given and an experiment focuses on critical speed identification is carried out.

Findings

The theoretical calculation results indicate that the critical speed is near to 800 rpm and there is no large vibration amplitude round working speed (1,500 rpm). Using the test bench in the factory unit, vibration data including three experimental processes are obtained. According to the vibration data, the critical speed is identified which also indicates that it is stable when working at 1,500 rpm.

Originality/value

The design method for the rotor system supported by large diameter elliptical bearing can be obtained by the theoretical and experimental results shown in this paper.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0122/

Details

Industrial Lubrication and Tribology, vol. 73 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 10 August 2018

Ming Qiu, Rui Zhang, Yingchun Li, Hui Du and Xiao Xu Pang

The MoS2/graphite composite coatings modified by La2O3 through spraying technique were successfully prepared on the inner rings of spherical plain bearings. As a…

Abstract

Purpose

The MoS2/graphite composite coatings modified by La2O3 through spraying technique were successfully prepared on the inner rings of spherical plain bearings. As a comparison, unmodified coatings were also prepared. This paper aims to study the La-modified MoS2/graphite composite coating experimentally and improve the tribological performance of self-lubricating spherical plain bearings.

Design/methodology/approach

The performance of La2O3 toward the friction coefficient, temperature rise and wear rate of the coatings was studied by a self-made tribo-tester under different swing cycles. And the texture, surface morphology and element composition of the coatings were characterized by scanning electron microscope, energy dispersive spectroscopy and X-ray diffractometry.

Findings

The additives La2O3 refined the coatings’ microstructure and improved the tribological properties of the coatings. The oxidation of Mo + 4 to Mo + 6 was effectively inhibited. And the amount of abrasive grains, peeling pits and local cracks on the coatings surface decreased and homogeneous lubricating films formed, which were attributed to the existence of La2O3. The wear mechanisms of unmodified coatings were severe abrasive wear, adhesive wear and delamination wear. However, it exhibited superior wear resistance of the La-modified coatings to unmodified coatings, presenting slight abrasive wear and adhesive wear. The service life of bearings was prolonged under the protection of the modified coatings.

Originality/value

The paper proposed a new modified MoS2/Graphite composite coating for the self-lubricating spherical plain bearings. The investigation on the friction, wear and temperature increase behaviors and the wear mechanisms of the coatings are beneficial to prolonging the service life of the self-lubricating spherical plain bearings.

Details

Industrial Lubrication and Tribology, vol. 70 no. 8
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 2 March 2020

Zhiming Zhao and Rui Zhang

The hydrodynamic characteristics of liquid film for bearings, especially water-lubricated bearings with a large length-to-diameter ratio, affect the dynamics behavior of…

Abstract

Purpose

The hydrodynamic characteristics of liquid film for bearings, especially water-lubricated bearings with a large length-to-diameter ratio, affect the dynamics behavior of rotor bearing systems. The purpose of this study is to carry out theoretical analysis and experiments to determine the hydrodynamic characteristics of water-lubricated journal bearings.

Design/methodology/approach

The finite difference method is adopted for the simulation of the characteristics of water-lubricated bearings. The comparison results between water-lubricated bearings with and without grooves, as well as with and without the consideration of the effects of rubber deformation, are presented. The test bearings, test bench, and monitoring system, especially the force exciter for the bearing experiment, are presented. Dynamic coefficient identification verification experiments were performed in different working situations. The obtained results include the calibration of magnetic force, two kinds of excitation, vibration data of the rotor system and dynamic coefficients.

Findings

The theoretical results demonstrate that the hydrodynamic effect was obvious when the speed was increased and that the water film had improved capability at a working speed of 1800 rpm. The identification results reveal the lubrication situation of the test bearing under low-speed and high-load conditions. Moreover, it was found that the liquid film was not continuous at low speeds.

Originality/value

The theoretical results can lead to the enhancement of the design level of water-lubricated rubber journal bearings with a large aspect ratio. The experimental results can lead to the improvement of the dynamic behavior design of rotor systems supported using water-lubricated bearings with a large length-to-diameter ratio.

Details

Industrial Lubrication and Tribology, vol. 72 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 24 June 2019

Khurram Ashfaq and Zhang Rui

The purpose of this paper is to investigate the internal control disclosure (ICDISC) practices in South Asia and compare those disclosure practices across enforced setting…

Abstract

Purpose

The purpose of this paper is to investigate the internal control disclosure (ICDISC) practices in South Asia and compare those disclosure practices across enforced setting (India) versus comply or explain setting (Pakistan and Bangladesh). Further, whether the audit firm size moderates the relationship between ICDISC practices and board & audit committee effectiveness.

Design/methodology/approach

To achieve these objectives, a sample of 100 non-financial companies was selected from Pakistan and India for three years’ period (2013-2015), whereas 93 companies were selected from Bangladesh based on market capitalization. The ICDISC index has been used which is based on the COSO framework.

Findings

Results of univariate analysis show that public sector companies in South Asia tend to disclose significantly more internal control information as compared to private sector companies. In terms of enforcement variable, the results of Mann–Whitney test show that companies listed in enforced setting have disclosed significantly greater extent of overall as well as individual categories of ICDISC as compared to companies listed in comply or explain setting. Based on multivariate analysis results for overall sample, it was found that board and audit committee characteristics and ownership by government have positive significant effect on ICDISC except representation of female or foreigner on audit committee which was found negatively significant. In addition to this, listing on foreign stock exchange and enforcement effect emerged as significant variables to influence ICDISC. Finally, the results of additional analysis state that the role of board and audit committee for influencing ICDISC has been moderated by the external auditor size in South Asia. In addition, enforcement variable is highly positively significant for companies having non-big four audit firm.

Research limitations/implications

These results imply that enforcement variable acts as an important alternative external control mechanism when companies do not have big four audit firm as their external auditors.

Originality/value

This is very first study on ICDISC in South Asia which explores the effect of enforcement and governance on ICDISC practices of firms. It also contributes toward the literature that the regulation on reporting of internal control can be effective in developing country only if there is strong penalty for non-compliance by regulatory authorities.

Details

Journal of Financial Reporting and Accounting, vol. 17 no. 2
Type: Research Article
ISSN: 1985-2517

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Article
Publication date: 18 January 2016

Rui Zhang, Wendong Zhang, Changde He, Jinlong Song, Linfeng Mu, Juan Cui, Yongmei Zhang and Chenyang Xue

The purpose of this paper was to develop a novel capacitive micromachined ultrasonic transducer (CMUT) reception and transmission linear array for underwater imaging at…

Abstract

Purpose

The purpose of this paper was to develop a novel capacitive micromachined ultrasonic transducer (CMUT) reception and transmission linear array for underwater imaging at 400 kHz. Compared with traditional CMUTs, the developed transducer array offers higher electromechanical coupling coefficient and higher directivity performance.

Design/methodology/approach

The configuration of the newly developed CMUT reception and transmission array was determined by the authors’ previous research into new element structures with patterned top electrodes and into directivity simulation analysis. Using the Si-Silicon on insulator (Si-SOI) bonding technique and the principle of acoustic impedance matching, the CMUT array was fabricated and packaged. In addition, underwater imaging system design and testing based on the packaged CMUT 1 × 16 array were completed.

Findings

The simulation results showed that the optimized CMUT array configuration was selected. Furthermore, the designed configuration of the CMUT 1 × 16 linear array was good enough to guarantee high angular resolution. The underwater experiments were conducted to demonstrate that this CMUT array can be of great benefit in imaging applications.

Practical implications

Based on our research, the CMUT linear array has good directivity and good impedance matching with water and can be used for obstacle avoidance, distance measurement and imaging underwater.

Originality/value

This research provides a basis for CMUT directivity theory and array design. CMUT array presented in this paper has good directivity and has been applied in the underwater imaging, resulting in a huge market potential in underwater detection systems.

Details

Sensor Review, vol. 36 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

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