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Article
Publication date: 16 January 2017

Peng Wu, Shaorong Xie, Hengli Liu, Ming Li, Hengyu Li, Yan Peng, Xiaomao Li and Jun Luo

Autonomous obstacle avoidance is important in unmanned surface vehicle (USV) navigation. Although the result of obstacle detection is often inaccurate because of the inherent…

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Abstract

Purpose

Autonomous obstacle avoidance is important in unmanned surface vehicle (USV) navigation. Although the result of obstacle detection is often inaccurate because of the inherent errors of LIDAR, conventional methods typically emphasize on a single obstacle-avoidance algorithm and neglect the limitation of sensors and safety in a local region. Conventional methods also fail in seamlessly integrating local and global obstacle avoidance algorithms. This paper aims to present a cooperative manoeuvring approach including both local and global obstacle avoidance.

Design/methodology/approach

The global algorithm used in our USV is the Artificial Potential Field-Ant Colony Optimization (APF-ACO) obstacle-avoidance algorithm, which plans a relative optimal path on the specified electronic map before the cruise of USV. The local algorithm is a multi-layer obstacle-avoidance framework based on a single LIDAR to present an efficient solution to USV path planning in the case of sensor errors and collision risks. When obstacles are within a layer, the USV uses a corresponding obstacle-avoidance algorithm. Then the USV moves towards the global direction according to fuzzy rules in the fuzzy layer.

Findings

The presented method offers a solution for obstacle avoidance in a complex environment. The USV follows the global trajectory planed by the APF-ACO algorithm. While, the USV can bypass current obstacle in the local region based on the multi-layer method effectively. This fact was validated by simulations and field trials.

Originality/value

The method presented in this paper takes advantage of algorithm integration that remedies errors of obstacle detection. Simulation and experiments were also conducted for performance evaluation.

Details

Industrial Robot: An International Journal, vol. 44 no. 1
Type: Research Article
ISSN: 0143-991X

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Article
Publication date: 25 June 2024

Zhicai Yu, Lili Wang, Yiwei Shao, Yun Liu, Yuhang Zhao, Yi Qin, Yingzi Zhang and Hualing He

This study aims to fabricate a novel electromagnetic interference (EMI) shielding composite aerogel with both thermal insulation and high temperature warning functions.

51

Abstract

Purpose

This study aims to fabricate a novel electromagnetic interference (EMI) shielding composite aerogel with both thermal insulation and high temperature warning functions.

Design/methodology/approach

An emerging bio-based polypyrrole (PPy) gel/Fe3O4/calcium alginate (PFC) EMI shielding composite aerogel was prepared by freeze-drying and in situ polymerization method. First, Fe3O4/calcium alginate (CA) aerogel was obtained by freeze-drying the Fe3O4/CA mixture. Then, PPy/Fe3O4/CA was obtained by synthesizing PPy on the surface of CA/Fe3O4 aerogel through in situ polymerization. Finally, PPy/Fe3O4/CA was immersed in porphyrin solution (cross-linking agent) to get the final PFC EMI shielding composite aerogel.

Findings

Due to the matched impedance between Fe3O4 and PPy, the EMI shielding performance of PFC composite aerogel can reach up to −8 dB. In addition, the PFC EMI shielding composite aerogel also shows excellent self-extinguishing and thermal insulation properties. After leaving the flame, the burning PFC aerogel is quickly extinguished. When the PFC aerogel is placed on the heating plate at 230 °C, the temperature on the side of the aerogel away from the heating plate is only 90.3 °C after 5 min of heating. The electrical resistance of the PFC composite aerogel can be reduced from 3.62 × 104 O to 5 × 102 O to trigger the warning light after 3 s of exposure to the alcohol lamp flame. This reversible thermal resistance response characteristic can be used to give an early warning signal when the PFC encounters high temperature or flame.

Originality/value

This work provides a novel strategy for designing a multifunctional EMI shielding composite aerogel with repeatable high temperature warning performance. This PFC composite aerogel shows potential applications in the prevention of material combustion in high temperature electromagnetic environments.

Details

Pigment & Resin Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 18 January 2016

Shaorong Xie, Peng Wu, Hengli Liu, Peng Yan, Xiaomao Li, Jun Luo and Qingmei Li

This paper aims to propose a new method for combining global path planning with local path planning, to provide an efficient solution for unmanned surface vehicle (USV) path…

975

Abstract

Purpose

This paper aims to propose a new method for combining global path planning with local path planning, to provide an efficient solution for unmanned surface vehicle (USV) path planning despite the changeable environment. Path planning is the key issue of USV navigation. A lot of research works were done on the global and local path planning. However, little attention was given to combining global path planning with local path planning.

Design/methodology/approach

A search of shortcut Dijkstra algorithm was used to control the USV in the global path planning. When the USV encounters unknown obstacles, it switches to our modified artificial potential field (APF) algorithm for local path planning. The combinatorial method improves the approach of USV path planning in complex environment.

Findings

The method in this paper offers a solution to the issue of path planning in changeable or unchangeable environment, and was confirmed by simulations and experiments. The USV follows the global path based on the search of shortcut Dijkstra algorithm. Both USV achieves obstacle avoidances in the local region based on the modified APF algorithm after obstacle detection. Both the simulation and experimental results demonstrate that the combinatorial path planning method is more efficient in the complex environment.

Originality/value

This paper proposes a new path planning method for USV in changeable environment. The proposed method is capable of efficient navigation in changeable and unchangeable environment.

Details

Industrial Robot: An International Journal, vol. 43 no. 1
Type: Research Article
ISSN: 0143-991X

Keywords

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Article
Publication date: 28 November 2022

Huiru Li, Xinyi Liu, Hengli Zhou and Zhiyong Li

A proliferation of articles surrounding the COVID-19 pandemic is calling for new insights through review. This paper aims to bibliometrically analyze the current progress of…

972

Abstract

Purpose

A proliferation of articles surrounding the COVID-19 pandemic is calling for new insights through review. This paper aims to bibliometrically analyze the current progress of research around hospitality and tourism to define the research directions on herd immunity and the prevention of disease under the “new normal.”

Design/methodology/approach

This paper analyzed 326 articles regarding COVID-19 published in SSCI hospitality, leisure and tourism journals in 2020 and 2021 by combining manual analysis and bibliometrics to reveal research topics and to gain insight into research structures.

Findings

The results of this paper summarized topics related to stakeholders’ mentality and behavior, responses of travel suppliers to the COVID-19 pandemic, economic impact and demand forecasting, social issues of human rights and racism and reflection on tourism and transformation of the industry. More research is called for in the future to focus on a better response to the crisis, including crisis management education and training and the improving the resilience of small- and medium-sized enterprises.

Research limitations/implications

A three-dimensional consideration was proposed to promote the sustainable development of hospitality and tourism.

Originality/value

In the “new normal” phase of herd immunity and disease prevention, to the best of the authors’ knowledge, this is the first paper that provides an up-to-date systematic overview of the evolution of COVID-19 research in tourism and hospitality and encourages more conceptual, practical and futuristic studies.

Details

International Journal of Contemporary Hospitality Management, vol. 35 no. 7
Type: Research Article
ISSN: 0959-6119

Keywords

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Article
Publication date: 20 June 2019

Yongmei Zhu, Junjie Chen, Jiajun Du, Yujie Fan and Jifei Zheng

Previous publications were mainly focused on the effect of textures under lubrication. Under dry sliding, area ratio of surface texturing (pit area ratio) and diameter of pit…

159

Abstract

Purpose

Previous publications were mainly focused on the effect of textures under lubrication. Under dry sliding, area ratio of surface texturing (pit area ratio) and diameter of pit affect the tribological behavior. This paper aims to investigate the effect of laser surface texturing on tribological behavior of nodular cast iron under dry sliding.

Design/methodology/approach

Pit-like textures with different diameters and spaces were fabricated by laser on nodular cast iron (QT600-3). Using nodular cast iron (QT600-3) as the disc specimen and resin matrix composites (UCV018) as the pad specimen, the tribological test was performed with pin-on-disk reciprocating tribo-tester.

Findings

The coefficient of friction (COF) of the non-textured specimen was larger than that of the textured one. For the same pit diameter, a larger pit area ratio induced a slight decrease of COF, while wear volume decreased significantly. The pit diameter induced a slight decrease of COF as the pit area ratio, but its effect was weaker.

Practical implications

The experimental studies will help to improve the brake system such as structure modeling of brake disc. Predicting the performance and life of the brake disc in vehicle based on tribological behavior checked in test, it was proved that pit-like texture had application value in vehicle brake system.

Originality/value

This paper showed that the effect of pit area ratio on friction and wear was greater than that of pit diameter. The experimental results will be useful to the design on safety brake disc.

Details

Industrial Lubrication and Tribology, vol. 71 no. 7
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 15 April 2022

Hongxia Ma, Wei Wu, Heng Zhang and Zeyun Wang

This paper aims to propose a new strategy to functionalize zeolitic imidazolate frameworks (ZIF-8) to improve its dispersion stability and tribological properties in lubricating…

251

Abstract

Purpose

This paper aims to propose a new strategy to functionalize zeolitic imidazolate frameworks (ZIF-8) to improve its dispersion stability and tribological properties in lubricating oil.

Design/methodology/approach

Dialkyl dithiophosphate polydopamine ZIF-8 (DDP@PDA@ZIF-8) was prepared via mussel-inspired chemistry and the Michael addition reaction. The tribological properties of DDP@PDA@ZIF-8 as an additive in the white oil were evaluated with four-ball friction and wear tester at different temperatures. The worn surface was analyzed using X-ray photoelectron spectrum (XPS).

Findings

The as-prepared DDP@PDA@ZIF-8 shows high dispersion stability in the white oil. Tribological results confirmed that the DDP@PDA@ZIF-8 exhibited a small wear scar diameter at 25°C. However, excellent friction reduction and anti-wear properties were observed at 75°C. The XPS result indicates that a series of tribochemical reactions occurred on the worn surface, forming the complex protective film.

Originality/value

This paper provides a study of highly dispersed ZIF-8 as lubrication additives.

Details

Industrial Lubrication and Tribology, vol. 74 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 18 December 2024

Liangwei Zhang and Yayun Qi

To reduce the wheel maintenance costs caused by wheel wear and to transition from traditional periodic maintenance to condition-based maintenance for railway freight wagons, it is…

12

Abstract

Purpose

To reduce the wheel maintenance costs caused by wheel wear and to transition from traditional periodic maintenance to condition-based maintenance for railway freight wagons, it is necessary to investigate the prediction of wheel wear and understand the evolution rule of wheel profile wear.

Design/methodology/approach

This paper established a wheel wear prediction model for railway freight wagons based on Archard’s wear theory and proposed a prediction method that combines vehicle system dynamic, interpolation iteration and intelligent simulation. The wear coefficients in the model were obtained through wheel wear tests by using the roller rig. The model’s effectiveness was further verified through line testing and simulation models, and the corrected wear coefficient can be used for wear prediction of heavy-haul freight wagons in China.

Findings

The wheel wear prediction showed that the results of the wheel wear prediction model by adopting the wear coefficients obtained from the roller rig tests are close to the actual wheel wear, with the difference of the maximum in wear depth at the nominal rolling circle being within 7%.

Originality/value

This paper proposed a method that can establish a database of wheel wear coefficients for predicting wheel wear of railway freight wagons under similar operating conditions. The revised wear coefficient can be used for wear prediction of heavy-haul freight wagons in China.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2024-0329/

Details

Industrial Lubrication and Tribology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 28 April 2020

Karl Yan

What are the mechanisms through which Chinese municipal leaders overcome implementation breakdown? This study, through process tracing, archival work and semi-structured…

108

Abstract

Purpose

What are the mechanisms through which Chinese municipal leaders overcome implementation breakdown? This study, through process tracing, archival work and semi-structured interviews, examines the implementation of three sub-municipal-level railway projects involving the same principals and agents over the same period of time.

Design/methodology/approach

The analysis was guided by the hypothesis that political coordination and the exercise of political and Party leadership played an indispensable role in the two cases of successful policy implementation, and its absence accounts for the case of implementation breakdown.

Findings

The principal finding is that an informal “strategic group” was created to “herd” cadres to overcome the problem of implementation. Herding here refers to the idea that Party leadership, through the use of moral persuasion, encourages cadres moving towards a desired common goal and direction.

Research limitations/implications

This study is limited in the number of secondary resources (government documents and government and media releases) available to the field interviewees, which the author heavily relied on to complete the study.

Originality/value

Building on the conceptual work of “strategic groups” by Thomas Heberer, Anna Ahlers, and Gunter Schubert, this study makes an empirical contribution by tracing the process through which an informal strategic group exercises its power to overcome implementation breakdown.

Details

Asian Education and Development Studies, vol. 9 no. 3
Type: Research Article
ISSN: 2046-3162

Keywords

Available. Content available
Article
Publication date: 4 August 2021

Yuwei Yin and Jasmine Siu Lee Lam

This study aims at investigating how energy strategies of China impact its energy shipping import through a strategic maritime link, the Straits of Malacca and Singapore (SOMS).

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Abstract

Purpose

This study aims at investigating how energy strategies of China impact its energy shipping import through a strategic maritime link, the Straits of Malacca and Singapore (SOMS).

Design/methodology/approach

Vector error-correction modelling (VECM) is applied to examine the key energy strategies of China influencing crude oil and liquefied natural gas (LNG) shipping import via the SOMS. Strategies investigated include oil storage expansions, government-setting targets to motivate domestic gas production, pipeline projects to diversify natural gas import routes and commercial strategies to ensure oil and gas accessibility and cost-effectiveness.

Findings

For the crude oil sector, building up oil storage and diversifying oil import means, routes and sources were found effective to mitigate impacts of consumption surges and price shocks. For the LNG sector, domestic production expansion effectively reduces LNG import. However, pipeline gas import growth is inefficient to relieve LNG shipping import dependency. Furthermore, energy companies have limited flexibility to adjust LNG shipping import volumes via the SOMS even under increased import prices and transport costs.

Practical implications

As the natural gas demand of China continues expanding, utilisation rates of existing pipeline networks need to be enhanced. Besides, domestic production expansion and diversification of LNG import sources and means are crucial.

Originality/value

This study is among the first in the literature using a quantitative approach to investigate how energy strategies implemented in a nation impact its energy shipping volumes via the SOMS, which is one of the most important maritime links that support 40% of the global trades.

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