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Article

Lei Guo, Lien Zhu, Lei Ma, Jian Zhang, QiuYu Meng, Zheng Jin, Meihua Liu and Kai Zhao

The purpose of this paper is to prepare a spherical modifier-modified activated carbon fiber of high specific capacitance intended for electrode materials of supercapacitor.

Abstract

Purpose

The purpose of this paper is to prepare a spherical modifier-modified activated carbon fiber of high specific capacitance intended for electrode materials of supercapacitor.

Design/methodology/approach

In this study, phenolic-based microspheres are taken as modifiers to prepare PAN-based fiber composites by electrospinning, pre-oxidation and carbonization. Pearl-chain structures appear in RFC/ACF composites, and pure polyacrylonitrile fibers show a dense network. The shape and cross-linking degree are large. After the addition of the phenolic-based microspheres, the composite material exhibits a layered pearlite chain structure with a large porosity, and the RFC/ACF composite material is derived because of the existence of a large number of bead chain structures in the composite material. The density increases, the volume declines and the mass after being assembled into a supercapacitor as a positive electrode material decreases. The specific surface area of RFC/ACF composites is increased as compared to pure fibers. The increase in specific surface area could facilitate the diffusion of electrolyte ions in the material. Owing to the large number of bead chains, plenty of pore channels are provided for the diffusion of electrolyte ions, which is conducive to enhancing the electrochemical performance of the composite and improving the RFC/ACF composite and the specific capacitance of the material. The methods of electrochemical testing on symmetric supercapacitors (as positive electrodes) are three-electrode cyclic voltammetry, alternating current impedance and cycle stability.

Findings

The specific capacitance value of the composite material was found to be 389.2 F/g, and the specific capacitance of the electrode operating at a higher current density of 20 mA/cm2 was 11.87 F/g (the amount of the microsphere modifier added was 0.3 g). Using this material as a positive electrode to assemble into asymmetrical supercapacitor, after 2,000 cycles, the specific capacitance retention rate was 87.46 per cent, indicating excellent cycle stability performance. This result can be attributed to the fact that the modifier embedded in the fiber changes the porosity between the fibers, while improving the utilization of the carbon fibers and making it easier for electrolyte ions to enter the interior of the composites, thereby increasing the capacitance of the composites.

Originality/value

The modified PAN-based activated carbon fibers in the study had high specific surface area and significantly high specific capacitance, which makes it applicable as an efficient and environment-friendly absorbent, as well as an advanced electrode material for supercapacitor.

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Article

Zhu Feng, Shaotao Zhi, Lei Guo, Chong Lei and Yong Zhou

This paper aims to investigate magnetic field anneal in micro-patterned Co-based amorphous ribbon on giant magneto-impedance (GMI) effect enhancement.

Abstract

Purpose

This paper aims to investigate magnetic field anneal in micro-patterned Co-based amorphous ribbon on giant magneto-impedance (GMI) effect enhancement.

Design/methodology/approach

The amorphous ribbons were annealed in transverse and longitudinal magnetic field. The influence of different field annealing directions on GMI effect and impedance Z, resistance R and reactance X with a series of line width have been deeply analyzed.

Findings

In comparison with GMI sensors microfabricated by unannealed and transversal field annealed ribbons, GMI sensor which was designed and microfabricated by longitudinal field anneal ribbon performs better. The results can be explained by the domain wall motion and domain rotation during annealing process and the geometric structure of Co-based GMI sensor. In addition, shrinking the line width of GMI sensor can promote GMI effect significantly because of the effect of demagnetizing field, and the optimum GMI ratio is 209.7 per cent in longitudinal field annealed GMI sensor with 200 μm line width.

Originality/value

In conclusion, annealing in longitudinal magnetic field and decreasing line width can enhance GMI effect in micro-patterned Co-based amorphous ribbon.

Details

Sensor Review, vol. 39 no. 3
Type: Research Article
ISSN: 0260-2288

Keywords

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Article

Jian Yang, Ben Niu, Tao Du, Xin Liu, Shanpeng Wang and Lei Guo

Multiple-source disturbances exist in the polarization sensor, which severely affect the sensor accuracy and stability. Hence, the disturbance analysis plays a vital role…

Abstract

Purpose

Multiple-source disturbances exist in the polarization sensor, which severely affect the sensor accuracy and stability. Hence, the disturbance analysis plays a vital role in improving the sensor orientation performance. This paper aims to present a novel sensor error model, a disturbances quantitative analysis, a calibration and performance test of polarization sensor based on a polarizing beam splitter.

Design/methodology/approach

By combining with the sensor coefficient errors, the Azimuth of Polarization (AoP) error model and the Degree of Polarization (DoP) error model are established, respectively. In addition, the multiple-source disturbances are classified, while the influence on the orientation accuracy is quantitative analyzed. Moreover, the least square optimization algorithm is employed to calibrate the sensor coefficients. Finally, an outdoor test is carried out to test the sensor long-term accuracy.

Findings

The theoretical analysis and numerical simulations illustrate that the sensor accuracy is closely related to the disturbances. To eliminate the influence of the disturbances, the least square optimization algorithm, which can minimize the sum of squares of the residual difference of AoP and DoP, is used to calibrate the sensor coefficients. The outdoor test indicates that the sensor can maintain long-term accuracy and stability.

Originality/value

The main contribution of this paper is to establish a novel sensor error model, where the sensor coefficient errors are introduced. In addition, the disturbances are classified and analyzed to evaluate the orientation accuracy of the sensor.

Details

Sensor Review, vol. 39 no. 3
Type: Research Article
ISSN: 0260-2288

Keywords

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Article

Jia LIU, Yumin Zhang, Lei Guo and Xiaoying Gao

A full-order multi-objective anti-disturbance robust filter for SINS/GPS navigation systems with multiple disturbances is designed. Generally, the unmodeled dynamics, the…

Abstract

Purpose

A full-order multi-objective anti-disturbance robust filter for SINS/GPS navigation systems with multiple disturbances is designed. Generally, the unmodeled dynamics, the external environmental disturbance and the inertial apparatus random drift may exist simultaneously in an integrated navigation system, which can be classified into three type of disturbances, that is, the Gaussian noise, the norm bounded noise and the time correlated noise. In most classical studies, the disturbances in integrated navigation systems are classified as Gaussian noises or norm bounded noises, where the Kalman filtering or robust filtering can be employed, respectively. While it is not true actually, such assumptions may lead to conservative results. The paper aims to discuss these issues.

Design/methodology/approach

The Gaussian noises, the norm bounded noises and the time correlated noises in the integrated navigation system are considered simultaneously in this contribution. As a result, the time correlated noises are augmented as a part of system state of the integrated navigation system error model, the relative integrated navigation problem can be transformed into a full-order multi-objective robust filter design problem for systems with Gaussian noises and norm bounded disturbances. Certainly, the errors of the time correlated noises are estimated and compensated for high precision navigation purpose. Sufficient conditions for the existence of the proposed filter are presented in terms of linear matrix inequalities (LMIs) such that the system stability is guaranteed and the disturbance attenuation performance is achieved.

Findings

Simulations for SINS/GPS integrated navigation system given show that the proposed full-order multi-objective anti-disturbance filter, has stronger robustness and better precision when multiple disturbances exist, that is, the present algorithm not only can suppression the effect of white noises and norm bounded disturbance but also can estimate and compensate the modeled disturbance.

Originality/value

The proposed algorithm has stronger anti-disturbance ability for integrated navigation with multiple disturbances. In fact, there exist multiple disturbances in integrated navigation system, so the proposed scheme has important significance in applications.

Details

International Journal of Intelligent Computing and Cybernetics, vol. 6 no. 3
Type: Research Article
ISSN: 1756-378X

Keywords

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Article

Kasturi Sudam Patil and Elizabeth Rufus

The paper aims to focus on implantable antenna sensors used for biomedical applications. Communication in implantable medical devices (IMDs) is beneficial for continuous…

Abstract

Purpose

The paper aims to focus on implantable antenna sensors used for biomedical applications. Communication in implantable medical devices (IMDs) is beneficial for continuous monitoring of health. The ability to communicate with exterior equipment is an important aspect of IMD. Thus, the design of an implantable antenna for integration into IMD is important.

Design/methodology/approach

In this review, recent developments in IMDs, three types of antenna sensors, which are recommended by researchers for biomedical implants are considered. In this review, design requirements, different types of their antenna, parameters and characteristics in medical implants communication system (MICS) and industrial, scientific and medical (ISM) bands are summarized here. Also, overall current progress in development of implantable antenna sensor, its challenges and the importance of human body characteristics are described.

Findings

This article give information about the requirements of implantable antenna sensor designs, types of antennas useful to design implantable devices and their characteristics in MICS and ISM bands. Recent advancement in implantable devices has led to an improvement in human health.

Originality/value

The paper provides useful information on implantable antennas design for biomedical application. The designing of such antennas needs to meet requirements such as compact size, patients’ safety, communication ability and biocompatibility.

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Article

Chao Guo, Huai‐Ning Wu, Biao Luo and Lei Guo

The air‐breathing hypersonic vehicle (AHV) includes intricate inherent coupling between the propulsion system and the airframe dynamics, which results in an intractable…

Abstract

Purpose

The air‐breathing hypersonic vehicle (AHV) includes intricate inherent coupling between the propulsion system and the airframe dynamics, which results in an intractable nonlinear system for the controller design. The purpose of this paper is to propose an H∞ control method for AHV based on the online simultaneous policy update algorithm (SPUA).

Design/methodology/approach

Initially, the H∞ state feedback control problem of the AHV is converted to the problem of solving the Hamilton‐Jacobi‐Isaacs (HJI) equation, which is notoriously difficult to solve both numerically and analytically. To overcome this difficulty, the online SPUA is introduced to solve the HJI equation without requiring the accurate knowledge of the internal system dynamics. Subsequently, the online SPUA is implemented on the basis of an actor‐critic structure, in which neural network (NN) is employed for approximating the cost function and a least‐square method is used to calculate the NN weight parameters.

Findings

Simulation study on the AHV demonstrates the effectiveness of the proposed H∞ control method.

Originality/value

The paper presents an interesting method for the H∞ state feedback control design problem of the AHV based on online SPUA.

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Article

Feng Tai, Fu Guo, Jianping Liu, Zhidong Xia, Yaowu Shi, Yongping Lei and Xiaoyan Li

The purpose of this paper is to investigate the creep properties of Sn‐0.7Cu composite solder joints reinforced with optimal nano‐sized Ag particles in order to improve…

Abstract

Purpose

The purpose of this paper is to investigate the creep properties of Sn‐0.7Cu composite solder joints reinforced with optimal nano‐sized Ag particles in order to improve the creep performance of lead‐free solder joints by a composite approach.

Design/methodology/approach

The composite approach has been considered as an effective method to improve the creep performance of solder joints. Nano‐sized Ag reinforcing particles were incorporated into Sn‐0.7Cu solder by mechanically mixing. A systematic creep study was carried out on nano‐composite solder joints reinforced with optimal nano‐sized Ag particles and compared with Sn‐0.7Cu solder joints at different temperatures and stress levels. A steady‐state creep constitutive equation for nano‐composite solder joints containing the best volume reinforcement was established in this study. Microstructural features of solder joints were analyzed to help determine their deformation mechanisms during creep.

Findings

The creep activation energies and stress exponents of Ag particle‐enhanced Sn‐0.7Cu lead‐free based composite solder joints were higher than those of matrix solder joints under the same stress and temperature. Thus, the creep properties of nano‐composite solder joints are better than those of Sn‐0.7Cu solder joints.

Originality/value

The findings indicated that nano‐sized Ag reinforcing particles could effectively improve the creep properties of solder joints. A new steady‐state creep constitutive equation of nano‐composite solder joints was established. Deformation mechanisms of Sn‐0.7Cu solder and nano‐composite solder joints during creep were determined.

Details

Soldering & Surface Mount Technology, vol. 22 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

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Article

Lei Guo and Irene C.L. Ng

This paper aims to examine the driving factors of salespeople's relational behaviors in the business to business marketing context.

Abstract

Purpose

This paper aims to examine the driving factors of salespeople's relational behaviors in the business to business marketing context.

Design/methodology/approach

The hypotheses were tested through a quantitative study via an online survey. Data were collected from 224 salespeople dealing with business customers in manufacturing as well as service industries in China.

Findings

The results showed that perceived consequences, affect‐based judgment and salespeople's communal or exchange orientation influenced their relational behaviors. In particular, communal orientation, perceived reciprocity from the customer, and a liking for the customer positively affected relational behaviors, whilst exchange orientation had a negative impact on those behaviors.

Originality/value

This paper provides a framework of the antecedents to salespeople's relational behaviors in the business to business marketing context, filling in the gaps found in previous research by studying the driving factors, not the outcomes, of individual salespeople's relational behaviors.

Details

Journal of Business & Industrial Marketing, vol. 27 no. 5
Type: Research Article
ISSN: 0885-8624

Keywords

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Article

Ning Yin, Guizhi Xu, Shuai Zhang and Lei Guo

The purpose of the paper is to present a three-dimensional model and analyze the internal link between surface potential distribution and the electrical activity of lumbar…

Abstract

Purpose

The purpose of the paper is to present a three-dimensional model and analyze the internal link between surface potential distribution and the electrical activity of lumbar muscles with finite element method.

Design/methodology/approach

Finite element method.

Findings

The simulated results have shown that there is a significant difference of surface potential topography patterns between low back pain (LBP) patients and normal healthy control. The normal shows symmetrical in contrast with the asymmetrical LBP pattern.

Originality/value

It provides a new view to analyze lumbar muscle activity with finite element method, which has a potential clinical application on lumbar muscle function analysis and LBP rehabilitation assessment.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 1/2
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

Saisudha Rajagopal, Lei Guo and Bo Edvardsson

The purpose of this article is to identify enabling and inhibiting factors that influence patients during their consideration of medical tourism for their healthcare…

Abstract

Purpose

The purpose of this article is to identify enabling and inhibiting factors that influence patients during their consideration of medical tourism for their healthcare requirement. The research provides marketing and practice implications that help in promoting medical tourism service. Furthermore, the paper provides evidence from medical tourism service to establish the relationship between resource integration and adoption of the service.

Design/methodology/approach

The article takes a two‐pronged exploratory study approach, with study one focusing on analysing prospective medical tourists' emotional impediments in their consideration of the service, while study two analyses the factors that helped medical tourists who have already availed the service, overcome the impediments.

Findings

In this article, it is identified that resource integration, particularly social resources, has a major impact on individual's decision to adopt a service. The exploratory study indicates that perceived knowledge disadvantage, lack of perceived control, and lack of social support in the destination country lead causes emotional discomfort to medical tourists. The study also indicates that the ability to integrate social resources available to them helped prospective medical tourists in their assessment of medical tourism service prior to adopting it. The article establishes that integration of social resources enables the patients to overcome the emotional discomfort and thus pursues to adopt medical tourism service.

Originality/value

While previous medical tourism service research has primarily focused on cognitive factors in patients' decision making such as quality and cost of healthcare services in destination countries, this article throws light on the enabling and inhibiting factors that influence adoption of medical tourism service.

Details

International Journal of Quality and Service Sciences, vol. 5 no. 3
Type: Research Article
ISSN: 1756-669X

Keywords

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