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Article
Publication date: 12 March 2018

Che-Chih Tsao, Ho-Hsin Chang, Meng-Hao Liu, Ho-Chia Chen, Yun-Tang Hsu, Pei-Ying Lin, Yih-Lin Chou, Ying-Chieh Chao, Yun-Hui Shen, Cheng-Yi Huang, Kai-Chiang Chan and Yi-Hung Chen

The purpose of this paper is to propose and demonstrate a new additive manufacturing approach that breaks the layer-based point scanning limitations to increase fabrication speed…

395

Abstract

Purpose

The purpose of this paper is to propose and demonstrate a new additive manufacturing approach that breaks the layer-based point scanning limitations to increase fabrication speed, obtain better surface finish, achieve material flexibility and reduce equipment costs.

Design/methodology/approach

The freeform additive manufacturing approach conceptually views a 3D article as an assembly of freeform elements distributed spatially following a flexible 3D assembly structure, which conforms to the surface of the article and physically builds the article by sequentially forming the freeform elements by a vari-directional vari-dimensional capable material deposition mechanism. Vari-directional building along tangential directions of part surface gives surface smoothness. Vari-dimensional deposition maximizes material output to increase build rate wherever allowed and minimizes deposition sizes for resolution whenever needed.

Findings

Process steps based on geometric and data processing considerations were described. Dispensing and forming of basic vari-directional and vari-dimensional freeform elements and basic operations of joining them were developed using thermoplastics. Forming of 3D articles at build rates of 2-5 times the fused deposition modeling (FDM) rate was demonstrated and improvement over ten times was shown to be feasible. FDM compatible operations using 0.7 mm wire depositions from a variable exit-dispensing unit were demonstrated. Preliminary tests of a surface finishing process showed a result of 0.8-1.9 um Ra. Initial results of dispensing wax, tin alloy and steel were also shown.

Originality/value

This is the first time that both vari-directional and vari-dimensional material depositions are combined in a new freeform building method, which has potential impact on the FDM and other additive manufacturing methods.

Details

Rapid Prototyping Journal, vol. 24 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 10 August 2020

Haiyan Qiao, Hao Meng, Wei Ke, Quanxi Gao and Shaobo Wang

To improve the robustness of missile control system and reduce the error, a missile attitude adaptive control method based on active disturbance rejection control technology…

463

Abstract

Purpose

To improve the robustness of missile control system and reduce the error, a missile attitude adaptive control method based on active disturbance rejection control technology (ADRC) and BP neural network is innovatively proposed.

Design/methodology/approach

ADRC improves the performance of the missile control system by estimating and eliminating the total disturbance of the system. BP neural network adjusts the parameters of ADRC controller according to the state of the system to realize adaptive control. Based on the control system and missile dynamics model, the convergence analysis of the extended state observer and the stability analysis of the closed-loop system after embedding BP neural network are given.

Findings

The simulation results show that the adaptive control method can adjust the coefficient of error feedback rate according to the system input, output and error change rate, which accelerates the response speed of missile attitude angle and reduces the attitude angle error.

Practical implications

BP–ADRC further improves the robustness and environmental adaptability of the missile control system. The BP–ADRC control method proposed in this paper is proved feasible.

Originality/value

Different from the traditional ADRC, the BP–ADRC feedback signal proposed in this paper uses the output signal and its rate of the closed-loop system instead of the system state quantity estimated by extended state observer (ESO). This innovative method combined with BP neural network can make the system output meet the requirements when ESO has errors in the estimation of missile dynamics model.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 10
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 6 November 2017

Xian Zhang, Zhaoyang Yuan, Yang Qingxin, Zhaohui Wang, Hao Meng and Yao Jin

The purpose of the paper is to analyze the impact of coupling on the distribution of the magnetic field and study the characteristics of the magnetic flux density in the…

231

Abstract

Purpose

The purpose of the paper is to analyze the impact of coupling on the distribution of the magnetic field and study the characteristics of the magnetic flux density in the transmission process of the magnetic coupling resonant wireless power transmission (MCR-WPT) system, which provides guidance on the design of the WPT system.

Design/methodology/approach

In this study, a finite element simulation analysis was conducted and a three-dimensional (3D) electromagnetic field measurement platform was used.

Findings

It is shown that the distribution of the magnetic field, as well as the position of maximum magnetic flux density, will change when the coils are coupled. The simulation results of the magnetic field distribution, as well as the transmission performance, are different from those in practice. It cannot describe the actual performance of WPT system.

Originality/value

A 3D electromagnetic field measurement system and the host computer software are designed to help optimize the simulation and carry out more accurate and efficient research. The 3D electromagnetic field measurement system can be used to study the distribution of the spatial electromagnetic field, influencing factor, exposure and interoperability between different coils.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 23 August 2015

Juan Xie, Meixia Li, Yongjing Hao, Xiaocai Meng, Yuan Meng and Zhen Li

Using only zinc nitrate, ferric nitrate and sodium hydroxide as reactants, rod-like and flower-like α-Fe2O3/ZnO composites were prepared via a simple and rapid solution route by…

106

Abstract

Using only zinc nitrate, ferric nitrate and sodium hydroxide as reactants, rod-like and flower-like α-Fe2O3/ZnO composites were prepared via a simple and rapid solution route by controlling the composition of precursor solution. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-vis diffuse reflectance spectra (UV-vis DRS). Photocatalytic activity of the as-prepared α-Fe2O3/ZnO composites was evaluated by degradation of methyl orange (MO) under simulated solar light. The results indicated that both α-Fe2O3/ZnO composites possess higher photocatalytic activity than commercial P25 TiO2. In addition, possible reasons why α-Fe2O3/ZnO composites have excellent photocatalytic performance were discussed.

Details

World Journal of Engineering, vol. 12 no. 4
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 1 January 2012

Jian‐Xin Shen, He Hao, Meng‐Jia Jin and Wei‐Zhong Fei

The purpose is to present a sensorless control method by which high‐resolution rotor position information is estimated and used for phase‐advancing operation of a high‐speed…

298

Abstract

Purpose

The purpose is to present a sensorless control method by which high‐resolution rotor position information is estimated and used for phase‐advancing operation of a high‐speed permanent magnet (PM) brushless DC (BLDC) motor.

Design/methodology/approach

The proposed sensorless control approach uses hardware to observe the flux vector which is excited by rotor magnets. It can provide the rotor position which is the same as the phase angle of the observed flux vector.

Findings

High‐resolution rotor position signal of the BLDC motor for dynamic phase‐advancing control cannot be directly obtained from the conventional Hall‐effect sensors, or via the traditional back‐EMF‐based sensorless control strategies in which the back‐EMF may be even undetectable at high‐speed. The proposed rotor‐flux‐observer (RFO)‐based sensorless control method overcomes these problems, and meanwhile provides high‐resolution rotor position information for the phase‐advancing purpose.

Originality/value

The RFO‐based sensorless control is traditionally applied to PM brushless ac (BLAC) operations, where the motor voltage vector can be calculated from the inverter switching status. However, this is not readily applicable to a BLDC motor since the voltage of the floating phase cannot be calculated. Moreover, during high‐speed operation, the microprocessor may not be sufficiently fast to calculate the high‐resolution rotor position. Therefore, in this paper, it is proposed to use hardware to observe the rotor‐flux‐vector. The microprocessor only samples the vector's α‐ and β‐components and calculates the phase angle, hence, its burden is low. The proposed method is validated with a 1.8 kW 85,000 rpm BLDC motor system.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 11 September 2019

Y.J. Guo, W. Cheng and P.S. Liu

The purpose of this paper is to provide an investigation on a new kind of photocatalytic material, namely, the porous ceramic foam loading titanium dioxide, which can make an…

203

Abstract

Purpose

The purpose of this paper is to provide an investigation on a new kind of photocatalytic material, namely, the porous ceramic foam loading titanium dioxide, which can make an effective photocatalytic degradation of the methyl orange (MO) solution in the wastewater.

Design/methodology/approach

The natural zeolite powder has been used as the primary raw material to produce a sort of lightweight porous ceramic foam by impregnating polymer foam in slurry and then sintering. With the sol-gel method, a kind of open-cell reticular porous ceramic foam loading TiO2 film was obtained having a good photocatalytic action, and the resultant porous composite product presents the bulk density of 0.3~0.6 g/cm3 to be able to float on water.

Findings

The MO could tend to be completely degraded in the solution with a certain concentration by the TiO2-loaded ceramic foam irradiated with ultraviolet light, and this composite foam was found to have high degradation efficiency for the MO solution in a wide range of pH.

Originality/value

This work presents a TiO2-loaded ceramic foam that can effectively photo-catalyze to degrade the MO in water, and the degradation efficiency were examined under different conditions of the MO solution with various pH values.

Details

Multidiscipline Modeling in Materials and Structures, vol. 15 no. 6
Type: Research Article
ISSN: 1573-6105

Keywords

Available. Open Access. Open Access
Article
Publication date: 13 February 2025

Asis Kumar Sahu and Byomakesh Debata

This study examines the impact of firm-level climate risk exposure (FCRE) on firm stock liquidity by using a sample of Indian-listed firms from the financial years 2003–2004 to…

215

Abstract

Purpose

This study examines the impact of firm-level climate risk exposure (FCRE) on firm stock liquidity by using a sample of Indian-listed firms from the financial years 2003–2004 to 2022–2023. Further, it endeavors to investigate the moderating role of environmental, social and governance (ESG) disclosure in this relationship.

Design/methodology/approach

A novel text-based FCRE metric is introduced using a sophisticated Word2Vec model through a Python-generated algorithm for each firm and year based on the management discussions and analysis (MD&A) reports. The panel fixed effect model is used to study how FCRE affects stock liquidity.

Findings

The result shows that FCRE negatively affects firms’ stock liquidity, and the effect remains robust after addressing endogeneity concerns. In addition, we find that a high ESG disclosure rating significantly moderated the adverse effect of FCRE. Furthermore, our analysis reveals that investor sentiment, information quality, corporate life cycle and institutional holdings moderate the impact of FCRE on liquidity.

Practical implications

The study offers valuable insights for investors, managers and policymakers on integrating climate risk into investment strategies, improving corporate climate governance and shaping policies that incentivize sustainable corporate behavior.

Originality/value

To the best of our knowledge, this study is an early study to explore the relationship between firm-specific climate risk exposure and stock liquidity using advanced machine learning techniques. It contributes to the existing literature by illustrating how climate risk can lead to adverse market reactions while highlighting the critical roles of corporate ESG practices, investor sentiment and disclosure quality in influencing this relationship.

Details

China Accounting and Finance Review, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1029-807X

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Article
Publication date: 8 August 2016

Asma Chakri, Rabia Khelif and Mohamed Benouaret

The first order reliability method requires optimization algorithms to find the minimum distance from the origin to the limit state surface in the normal space. The purpose of…

1146

Abstract

Purpose

The first order reliability method requires optimization algorithms to find the minimum distance from the origin to the limit state surface in the normal space. The purpose of this paper is to develop an improved version of the new metaheuristic algorithm inspired from echolocation behaviour of bats, namely, the bat algorithm (BA) dedicated to perform structural reliability analysis.

Design/methodology/approach

Modifications have been embedded to the standard BA to enhance its efficiency, robustness and reliability. In addition, a new adaptive penalty equation dedicated to solve the problem of the determination of the reliability index and a proposition on the limit state formulation are presented.

Findings

The comparisons between the improved bat algorithm (iBA) presented in this paper and other standard algorithms on benchmark functions show that the iBA is highly efficient, and the application to structural reliability problems such as the reliability analysis of overhead crane girder proves that results obtained with iBA are highly reliable.

Originality/value

A new iBA and an adaptive penalty equation for handling equality constraint are developed to determine the reliability index. In addition, the low computing time and the ease implementation of this method present great advantages from the engineering viewpoint.

Details

Multidiscipline Modeling in Materials and Structures, vol. 12 no. 2
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 3 October 2016

Li Bian, Meixia Li, Yiwei Lian, Yongjing Hao and Juan Xie

This paper aims to report a novel preparation method of ZnO particles with different structures and their photocatalytic activity.

89

Abstract

Purpose

This paper aims to report a novel preparation method of ZnO particles with different structures and their photocatalytic activity.

Design/methodology/approach

ZnO powders are prepared by a facile, economical and environment-friendly aqueous solution route. X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy and UV-vis diffuse reflectance spectra are used to characterize the products. Photocatalytic activity of the samples is evaluated by degradation of organic pollutant pentachlorophenol under UV-vis irradiation.

Findings

It is found that three-dimensional ZnO hierarchical structures can be prepared via aqueous solution route without using any template or structure-directing agent, and the alkalinity of reaction solution is the key factor. All the as-prepared ZnO products have good catalytic activity under UV-vis light irradiation.

Originality/value

This report presents a simple method for the preparation of ZnO particles with excellent photocatalytic activity. Experimental results could provide useful reference for the treatment of chlorophenols in the future.

Details

World Journal of Engineering, vol. 13 no. 5
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 22 March 2011

Serdar Izmirli and Clive J.C. Phillips

This research aims to determine the relationship between the consumption of animal products and attitudes towards animals among university students in Eurasia.

3962

Abstract

Purpose

This research aims to determine the relationship between the consumption of animal products and attitudes towards animals among university students in Eurasia.

Design/methodology/approach

A survey was conducted with collaborators in each country who supervised volunteers to personally invite 16,777 students to take part. The sample was composed of 3,433 students from 103 universities in 11 Eurasian countries. ANOVA was used to compare the responses. All analyses were conducted using the statistical packages Minitab 15 and SPSS 15.

Findings

A total of 47 per cent of university students avoided some meat products, 4 per cent were vegetarians and 0.4 per cent vegans. Students avoiding some meat did so principally for environmental and health reasons, and beef and lamb were the meats most likely to be avoided. Vegetarians avoided meat mainly for health reasons. Vegans had greater concern about humans using animals than vegetarians, who in turn had greater concerns than those avoiding some meat.

Social implications

Avoidance of animal products was related to an increased level of concern for animal rights, animal experimentation and wildlife, with vegans demonstrating the greatest concern. This implied that students' attitudes to animal welfare and rights can affect animal product‐eating behaviours.

Originality/value

This study conflicts with previous studies by demonstrating that health rather than environment was a major reason for vegetarianism. The study highlights the importance of environmental, health and welfare concerns but not religion in avoidance of animal products.

Details

British Food Journal, vol. 113 no. 3
Type: Research Article
ISSN: 0007-070X

Keywords

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