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Article
Publication date: 23 August 2011

Xiangjian Chen, Di Li, Zhijun Xu and Yue Bai

Quadrotor micro aerial vehicle (MAV) is nonlinear and under actuated plant, and it is difficult to obtain an accurate mathematical model for quadrotor MAV due to…

Abstract

Purpose

Quadrotor micro aerial vehicle (MAV) is nonlinear and under actuated plant, and it is difficult to obtain an accurate mathematical model for quadrotor MAV due to uncertainties. The purpose of this paper is to propose one robust control strategy for quadrotor MAV to accommodate system uncertainties, variations, and external disturbances.

Design/methodology/approach

The robust control strategy is composed of two self‐organizing interval type‐II fuzzy neural networks (SOIT‐IIFNNs) and one PD controller: the PD controller is adopted to control the attitude and position; one of the SOIT‐IIFNNs is designed to learn the inverse model of quadrotor MAV online; the other SOIT‐IIFNNs is the copy of the former one to compensate for model errors, system uncertainties and external disturbances, both structure and parameters of SOIT‐IIFNNs are tuned online at the same time, and then the stability of the resulting quadrotor MAV closed‐loop control system is proved using Lyapunov stability theory.

Findings

The validity of the proposed control method has been verified through real‐time experiments. The experimental results show that the performance of SOIT‐IIFNNs is significantly improved compared with Backstepping‐based controller.

Practical implications

This approach has been used in quadrotor MAV, the controller works well, and it could guarantee quadrotor MAV control system with good performances under uncertainties, variations, and external disturbances.

Originality/value

The proposed SOIT‐IIFNNs controller is interesting for the design of an intelligent control scheme. The main contributions of this paper are: the overall closed‐loop control system is globally stable, demonstrated by Lyapunov stable theory; the tracking error can be asymptotically attenuated to a desired small level around zero by appropriate chosen parameters and learning rates; and the quadrotor MAV control system based on SOIT‐IIFNNs controller can achieve favorable tracking performance.

Details

International Journal of Intelligent Computing and Cybernetics, vol. 4 no. 3
Type: Research Article
ISSN: 1756-378X

Keywords

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Article
Publication date: 3 June 2014

Xiangjian Chen, Di Li, Zhijun Xu and Yue Bai

Micro aerial vehicle is nonlinear plant; it is difficult to obtain stable control for MAV attitude due to uncertainties. The purpose of this paper is to propose one robust…

Abstract

Purpose

Micro aerial vehicle is nonlinear plant; it is difficult to obtain stable control for MAV attitude due to uncertainties. The purpose of this paper is to propose one robust stable control strategy for MAV to accommodate system uncertainties, variations, and external disturbances.

Design/methodology/approach

First, by employing interval type-II fuzzy neural network (ITIIFNN) to approximate the nonlinearity function and uncertainty functions in the attitude angle dynamic model of micro aircraft vehicle (MAV). Then, the Lyapunov stability theorem is used to testify the asymptotic stability of the closed-loop system, the parameters of the ITIIFNN and gain of sliding mode control can be tuned on-line by adaptive laws based on Lyapunov synthesis approach, and the Lyapunov stability theorem has been used to testify the asymptotic stability of the closed-loop system.

Findings

The validity of the proposed control method has been verified through real-time experiments. The experimental results show that the performance of interval type-II fuzzy neural network based gain adaptive sliding mode controller (GASMC-ITIIFNN) is significantly improved compared with conventional adaptive sliding mode controller (CASMC), type-I fuzzy neural network based sliding mode controller (GASMC-TIFNN).

Practical implications

This approach has been used in one MAV, the controller works well, and which could guarantee the MAV control system with good performances under uncertainties, variations, and external disturbances.

Originality/value

The main original contributions of this paper are: the proposed control scheme makes full use of the nominal model of the MAV attitude control model; the overall closed-loop control system is globally stable demonstrated by Lyapunov stable theory; the tracking error can be asymptotically attenuated to a desired small level around zero by appropriate chosen parameters and learning rates; and the MAV attitude control system based on GASMC-ITIIFNN controller can achieve favourable tracking performance than GASMC-TIFNN and CASMC.

Details

International Journal of Intelligent Computing and Cybernetics, vol. 7 no. 2
Type: Research Article
ISSN: 1756-378X

Keywords

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Article
Publication date: 14 March 2015

ZhiJun Xu, Xiaobing Liu, Chunguang Bai and Lijie Hu

As green marketing is a critical function of green supply chain management, it has generated a great deal of discussion in public discourse and academic research…

Abstract

As green marketing is a critical function of green supply chain management, it has generated a great deal of discussion in public discourse and academic research. Interestingly, there is a gap in the research on how a company can effectively invest and manage various green marketing activities. Thus this paper aims to introduce a grey multiple criteria decision-making methodology to investigate the relationships between green marketing activities and performance outcomes (environmental and business performance). This paper seeks to make the following contributions to the green supply chain management literature. First, review the literature to identify implementation activities for green marketing from green supply chain management literature. Second, develop a methodology to evaluate relationships of green marketing activities by integrating grey number and rough set method. Third, obtain various decision rules relating the various green marketing activities to the environmental and/or business performance outcomes through an illustrative application within an incomplete information system. Knowing those rules to help in the implementation, management, and evaluation of these green marketing activities is valuable to both researchers and practitioners. Included in the discussion are insights into how these rules for individual and aggregated performance (environmental, business, and joint performance) may be evaluated. Practical and research implications of this work are detailed in the final section of this paper.

Details

International Journal of Innovation Science, vol. 7 no. 1
Type: Research Article
ISSN: 1757-2223

Keywords

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Article
Publication date: 20 March 2007

Brian Low

The paper aims to identify the challenges faced by Huawei Technologies, China's biggest telecommunications equipment manufacturer, as it makes the transition from an…

Abstract

Purpose

The paper aims to identify the challenges faced by Huawei Technologies, China's biggest telecommunications equipment manufacturer, as it makes the transition from an indigenously‐owned business to a potentially competitive global giant.

Design/methodology/approach

This is an inductive, interpretative case study complimented by hands‐on experience with the industry.

Findings

The paper finds that Huawei lies at a crossroads in a transitional telecommunication sector that is no longer isolated from global reforms and advancement. Through internationalisation the company has learned to compete by adjusting their mechanisms, learning instruments and focus.

Originality/value

The paper is useful for practitioners in that it shows how indigenous companies in latecomer industrialising countries like China can overcome the late mover position in some of the advanced markets they have entered. For academics it highlights the role of government in helping to construct competitive indigenous firms that could take on global giants.

Details

Journal of Business & Industrial Marketing, vol. 22 no. 2
Type: Research Article
ISSN: 0885-8624

Keywords

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Article
Publication date: 16 May 2016

Shuntao Liu, Zhixiong Yang, Zhijun Zhu, Liangliang Han, Xiangyang Zhu and Kai Xu

Slim and dexterous manipulators with long reaches can perform various exploration and inspection tasks in confined spaces. This paper aims to present the development of…

Abstract

Purpose

Slim and dexterous manipulators with long reaches can perform various exploration and inspection tasks in confined spaces. This paper aims to present the development of such a dexterous continuum manipulator for potential applications in the aviation industry.

Design/methodology/approach

Benefiting from a newly conceived dual continuum mechanism and the improved actuation scheme, this paper proposes a design of a slim and dexterous continuum manipulator. Kinematics modeling, simulation-based dimension synthesis, structural constructions and system descriptions are elaborated.

Findings

Experimental validations show that the constructed prototype possesses the desired dexterity to navigate through confined spaces with its kinematics calibrated and actuation compensation implemented. The continuum manipulator with different deployed tools (e.g. graspers and welding guns) would be able to perform inspections and other tasks at remote locations in constrained environments.

Research limitations/implications

The current construction of the continuum manipulator possesses quite some friction inside its structure. The bending discrepancy caused by friction could accumulate to an obvious level. It is desired to further reduce the friction, even though the actuation compensation had been implemented.

Practical implications

The constructed continuum manipulator could perform inspection and other tasks in confined spaces, acting as an active multi-functional endoscopic platform. Such a device could greatly facilitate routine tasks in the aviation industry, such as guided assembling, inspection and maintenance.

Originality/value

The originality and values of this paper mainly lay on the design, modeling, construction and experimental validations of the slim and dexterous continuum manipulator for the desired mobility and functionality in confined spaces.

Details

Industrial Robot: An International Journal, vol. 43 no. 3
Type: Research Article
ISSN: 0143-991X

Keywords

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Article
Publication date: 4 April 2016

Huihuang Zhao, Jianzhen Chen, Shibiao Xu, Ying Wang and Zhijun Qiao

The purpose of this paper is to develop a compressive sensing (CS) algorithm for noisy solder joint imagery compression and recovery. A fast gradient-based compressive…

Abstract

Purpose

The purpose of this paper is to develop a compressive sensing (CS) algorithm for noisy solder joint imagery compression and recovery. A fast gradient-based compressive sensing (FGbCS) approach is proposed based on the convex optimization. The proposed algorithm is able to improve performance in terms of peak signal noise ratio (PSNR) and computational cost.

Design/methodology/approach

Unlike traditional CS methods, the authors first transformed a noise solder joint image to a sparse signal by a discrete cosine transform (DCT), so that the reconstruction of noisy solder joint imagery is changed to a convex optimization problem. Then, a so-called gradient-based method is utilized for solving the problem. To improve the method efficiency, the authors assume the problem to be convex with the Lipschitz gradient through the replacement of an iteration parameter by the Lipschitz constant. Moreover, a FGbCS algorithm is proposed to recover the noisy solder joint imagery under different parameters.

Findings

Experiments reveal that the proposed algorithm can achieve better results on PNSR with fewer computational costs than classical algorithms like Orthogonal Matching Pursuit (OMP), Greedy Basis Pursuit (GBP), Subspace Pursuit (SP), Compressive Sampling Matching Pursuit (CoSaMP) and Iterative Re-weighted Least Squares (IRLS). Convergence of the proposed algorithm is with a faster rate O(k*k) instead of O(1/k).

Practical implications

This paper provides a novel methodology for the CS of noisy solder joint imagery, and the proposed algorithm can also be used in other imagery compression and recovery.

Originality/value

According to the CS theory, a sparse or compressible signal can be represented by a fewer number of bases than those required by the Nyquist theorem. The new development might provide some fundamental guidelines for noisy imagery compression and recovering.

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Article
Publication date: 7 September 2010

Zhijun Wang, Hezeng Li and Jingyuan Zhang

In a mobile ad hoc network (MANET), design of energy‐efficient routing schemes is essential for prolonging the network lifetime. The purpose of this paper is to show that…

Abstract

Purpose

In a mobile ad hoc network (MANET), design of energy‐efficient routing schemes is essential for prolonging the network lifetime. The purpose of this paper is to show that one way to achieve energy efficiency in routing is to utilize location information, which becomes practical due to the recent increasing availability of low‐cost and reliable positioning devices.

Design/methodology/approach

This paper proposes an eight‐direction forwarding virtual grid aided (VGA) routing scheme that uses location information to save energy. As a grid‐based scheme, VGA divides the whole network area into virtual grids.

Findings

By using eight‐direction forwarding, the proposed VGA scheme outperforms the previous four‐direction forwarding geographical adaptive fidelity (GAF) protocol. The proposed VGA scheme is motivated by the fact that, in the GAF protocol, forwarding to the four diagonal neighboring grids cannot be done in one single hop, although most nodes in these grids can hear the signal.

Originality/value

Theoretical analysis shows the eight‐direction forwarding protocol performs better than the four‐direction one unless the forwarding direction has an angle of less than 15 with the horizontal or vertical grid axis. Simulation supports the fact that the eight‐direction forwarding VGA scheme has better energy performance than the four‐direction forwarding GAF scheme without sacrificing any routing performance.

Details

International Journal of Pervasive Computing and Communications, vol. 6 no. 3
Type: Research Article
ISSN: 1742-7371

Keywords

Content available
Article
Publication date: 12 June 2017

Lichao Zhu, Hangzhou Yang and Zhijun Yan

The purpose of this paper is to develop a new method to extract medical temporal information from online health communities.

Abstract

Purpose

The purpose of this paper is to develop a new method to extract medical temporal information from online health communities.

Design/methodology/approach

The authors trained a conditional random-filed model for the extraction of temporal expressions. The temporal relation identification is considered as a classification task and several support vector machine classifiers are built in the proposed method. For the model training, the authors extracted some high-level semantic features including co-reference relationship of medical concepts and the semantic similarity among words.

Findings

For the extraction of TIMEX, the authors find that well-formatted expressions are easy to recognize, and the main challenge is the relative TIMEX such as “three days after onset”. It also shows the same difficulty for normalization of absolute date or well-formatted duration, whereas frequency is easier to be normalized. For the identification of DocTimeRel, the result is fairly well, and the relation is difficult to identify when it involves a relative TIMEX or a hypothetical concept.

Originality/value

The authors proposed a new method to extract temporal information from the online clinical data and evaluated the usefulness of different level of syntactic features in this task.

Details

International Journal of Crowd Science, vol. 1 no. 2
Type: Research Article
ISSN: 2398-7294

Keywords

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Article
Publication date: 13 April 2015

Yujuan Zhang, Yaohua Xu, Yuangbin Yang, Shengmao Zhang, Pingyu Zhang and Zhijun Zhang

The purpose of this paper is to synthesize oil-soluble copper (Cu) nanoparticles modified with free phosphorus and sulfur modifier and investigate its tribological…

Abstract

Purpose

The purpose of this paper is to synthesize oil-soluble copper (Cu) nanoparticles modified with free phosphorus and sulfur modifier and investigate its tribological properties as environment-friendly lubricating oil additives.

Design/methodology/approach

To improve the anti-oxidation properties of these nanoparticles, two kinds of surface modifiers, oleic acid and oleylamine were used simultaneously. The morphology, composition, structure and thermal properties of as-synthesized Cu nanoparticles were investigated by means of transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectrometry and differential thermal and thermogravimetric analysis. The tribological properties of as-synthesized Cu nanoparticles as an additive in liquid paraffin were evaluated with a four-ball friction and wear tester.

Findings

It has been found that an as-synthesized Cu nanoparticle has a size of 2-5 nm and can be well dispersed in organic solvents. Tribological properties evaluation results show that as-synthesized Cu nanoparticles possess excellent anti-wear properties as an additive in liquid paraffin. The reason lies in that as-synthesized surface-capped Cu nanoparticles are able to deposit on sliding steel surface and form a low-shearing-strength protective layer thereon, showing promising application as an environmentally acceptable lubricating oil additive, owing to its free phosphorus and sulfur elements characteristics.

Originality/value

Oil-soluble surface-modified Cu nanoparticles without phosphorus and sulfur were synthesized and its tribological properties as lubricating oil additives were also investigated in this paper. These results could be very helpful for application of Cu nanoparticles as environment-friendly lubricating oil additives.

Details

Industrial Lubrication and Tribology, vol. 67 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 28 January 2020

Xiang Li, Zhijun Li and Zihao Wen

This paper aims to introduce a novel 4D hyperchaotic fractional-order system which can produce one-to-four-wing hyperchaotic attractors. In the study of chaotic systems…

Abstract

Purpose

This paper aims to introduce a novel 4D hyperchaotic fractional-order system which can produce one-to-four-wing hyperchaotic attractors. In the study of chaotic systems with variable-wing attractors, although some chaotic systems can generate one-to-four-wing attractors, none of them are hyperchaotic attractors, which is incomplete for the dynamic characteristics of chaotic systems.

Design/methodology/approach

A novel 4D fractional-order hyperchaotic system is proposed based on the classical three-dimensional Lü system. The complex and abundant dynamic behaviors of the fractional-order system are analyzed by phase diagrams, bifurcation diagrams and the corresponding Lyapunov exponents. In addition, SE and C0 algorithms are used to analyze the complexity of the fractional-order system. Then, the influence of order q on the system is also investigated. Finally, the circuit is implemented using physical components.

Findings

The most particular interest is that the system can generate one-to-four-wing hyperchaotic attractors with only one parameter variation. Then, the hardware circuit experimental results tally with the numerical simulations, which proves the validity and feasibility of the fractional-order hyperchaotic system. Besides, under different initial conditions, coexisting attractors can be obtained by changing the parameter d or the order q. Then, the complexity analysis of the system shows that the fractional-order chaotic system has higher complexity than the corresponding integer-order chaotic system.

Originality/value

The circuit structure of the fractional-order hyperchaotic system is simple and easy to implement, and one-to-four-wing hyperchaotic attractors can be observed in the circuit. To the best of the knowledge, this unique phenomenon has not been reported in any literature. It is of great reference value to analysis and circuit realization of fractional-order chaotic systems.

Details

Circuit World, vol. 46 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

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