Search results

1 – 10 of 35
Click here to view access options
Article
Publication date: 6 September 2011

Cui Hutao, Cheng Xiaojun, Xu Rui and Cui Pingyuan

The purpose of this paper is to propose an attitude control algorithm for spacecraft with geometric constraints.

Abstract

Purpose

The purpose of this paper is to propose an attitude control algorithm for spacecraft with geometric constraints.

Design/methodology/approach

The geometric constraint is reformulated as a quadratic form when quaternion is used as attitude parameter, then the constraint is proved to be nonconvex and is further transformed to a convex one. By designing a new constraint formulation to satisfy the real constraint in the predictive horizon, the attitude control problem is reshaped to a convex planning problem which is based on receding horizon control.

Findings

The proposed algorithm is more effective in handling geometric constraints than previous research which used single step planning control.

Practical implications

With novel improvements to current methods for steering spacecraft from one attitude to another with geometric constraints, great attitude maneuver path can be achieved to protect instruments and meanwhile satisfy mission requirements.

Originality/value

The attitude control algorithm in this paper is designed especially for the satisfaction of geometric constraints in the process of attitude maneuver of spacecraft. By the application of this algorithm, the security of certain optical instruments, which is critical in an autonomous system, can be further assured.

Details

Aircraft Engineering and Aerospace Technology, vol. 83 no. 5
Type: Research Article
ISSN: 0002-2667

Keywords

Click here to view access options
Article
Publication date: 16 August 2021

Zhiguang Cheng, Behzad Forghani, Zhenbin Du, Lanrong Liu, Yongjian Li, Xiaojun Zhao, Tao Liu, Linfeng Cai, Weiming Zhang, Meilin Lu, Yakun Tian and Yating Li

This paper aims to propose and establish a set of new benchmark models to investigate and confidently validate the modeling and prediction of total stray-field loss inside…

Downloads
50

Abstract

Purpose

This paper aims to propose and establish a set of new benchmark models to investigate and confidently validate the modeling and prediction of total stray-field loss inside magnetic and non-magnetic components under harmonics-direct current (HDC) hybrid excitations. As a new member-set (P21e) of the testing electromagnetic analysis methods Problem 21 Family, the focus is on efficient analysis methods and accurate material property modeling under complex excitations.

Design/methodology/approach

This P21e-based benchmarking covers the design of new benchmark models with magnetic flux compensation, the establishment of a new benchmark measurement system with HDC hybrid excitation, the formulation of the testing program (such as defined Cases I–V) and the measurement and prediction of material properties under HDC hybrid excitations, to test electromagnetic analysis methods and finite element (FE) computation models and investigate the electromagnetic behavior of typical magnetic and electromagnetic shields in electrical equipment.

Findings

The updated Problem 21 Family (V.2021) can now be used to investigate and validate the total power loss and the different shielding performance of magnetic and electromagnetic shields under various HDC hybrid excitations, including the different spatial distributions of the same excitation parameters. The new member-set (P21e) with magnetic flux compensation can experimentally determine the total power loss inside the load-component, which helps to validate the numerical modeling and simulation with confidence. The additional iron loss inside the laminated sheets caused by the magnetic flux normal to the laminations must be correctly modeled and predicted during the design and analysis. It is also observed that the magnetic properties (B27R090) measured in the rolling and transverse directions with different direct current (DC) biasing magnetic field are quite different from each other.

Research limitations/implications

The future benchmarking target is to study the effects of stronger HDC hybrid excitations on the internal loss behavior and the microstructure of magnetic load components.

Originality/value

This paper proposes a new extension of Problem 21 Family (1993–2021) with the upgraded excitation, involving multi-harmonics and DC bias. The alternating current (AC) and DC excitation can be applied at the two sides of the model’s load-component to avoid the adverse impact on the AC and DC power supply and investigate the effect of different AC and DC hybrid patterns on the total loss inside the load-component. The overall effectiveness of numerical modeling and simulation is highlighted and achieved via combining the efficient electromagnetic analysis methods and solvers, the reliable material property modeling and prediction under complex excitations and the precise FE computation model using partition processing. The outcome of this project will be beneficial to large-scale and high-performance numerical modeling.

Click here to view access options
Article
Publication date: 6 November 2017

Xiaojun Zhao, Fanhui Meng, Zhiguang Cheng, Lanrong Liu, Junjie Zhang and Chao Fan

This paper aims to investigate an efficient approach to model the electromagnetic behaviors and predict stray-field loss inside the magnetic steel plate under 3D harmonic…

Abstract

Purpose

This paper aims to investigate an efficient approach to model the electromagnetic behaviors and predict stray-field loss inside the magnetic steel plate under 3D harmonic magnetization conditions so as to effectively prevent the structural components from local overheating and insulation damage in electromagnetic devices.

Design/methodology/approach

An experimental setup is applied to measure all the magnetic properties of magnetic steel plate under harmonic excitations with different frequencies and phase angles. The measurement and numerical simulation are carried out based on the updated TEAM Problem 21 Model B+ (P210-B+), under the 3D harmonic magnetization conditions. An improved method to evaluate the stray-field loss is proposed, and harmonic flux distribution in the structural components is analyzed.

Findings

The influence of the harmonic order and phase angle on the stray-field loss in magnetic steel components are noteworthy. Based on the engineering-oriented benchmark models, the variations of stray-field losses and magnetic field distribution inside the magnetic components under harmonic magnetization conditions are presented and analyzed in detail.

Research limitations/implications

The capacity of the multi-function harmonic source, used in this work, was not large enough, which limits the magnetization level. Up to now, further improvements to increase the harmonic source capacity and investigations of the electromagnetic behaviors of magnetic steel components under multi-harmonic and DC-AC hybrid excitations are in progress.

Originality/value

To accurately predict the stray-field loss in magnetic steel plate, the improved method based on the combination of magnetic measurement and numerical simulation is proposed. The effects of the frequency and phase angle on the stray-field loss are analyzed.

Details

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

Keywords

Click here to view access options
Article
Publication date: 7 June 2021

Baoguang Ma, Cheng Chen, Xiaojun Xie, Yanhui Chen, Qiuyu Zhang, Dong Lv and Zhenguo Liu

The purpose of this study is to provide effective and environmental-friendly corrosion inhibitors derived from graphene oxide for Q235 steel.

Abstract

Purpose

The purpose of this study is to provide effective and environmental-friendly corrosion inhibitors derived from graphene oxide for Q235 steel.

Design/methodology/approach

Nontoxic and environment-friendly 4-aminobenzoic acid was used to functionalize graphene oxide via amidation and diazotization. The obtained amidation 4-aminobenzoic acid functionalized graphene oxide (PAGO) and diazotization 4-aminobenzoic acid functionalized graphene oxide (PDGO) were characterized by FTIR, Raman and TEM, while the inhibition efficiencies were analyzed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). Furthermore, theoretical inhibition efficiencies were investigated by density functional theory (DFT) approach.

Findings

At a concentration of 40 ppm, the maximum inhibition efficiency of PAGO and PDGO were 97.90% and 96.72% in EIS measurement, respectively, which were in accordance with PDP data. Moreover, experimental results were supported by DFT-based quantum chemical calculation.

Originality/value

Environmental-friendly PAGO and PDGO were synthesized successfully. The synthetic inhibitors exhibited excellent inhibition efficiencies in EIS and PDP measurements. Furthermore, a computational study using DFT supported the trend that PAGO was better inhibitor than PDGO.

Details

Anti-Corrosion Methods and Materials, vol. 68 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

Click here to view access options
Article
Publication date: 2 March 2012

Xiaojun Zhao, Lin Li, Junwei Lu, Zhiguang Cheng and Tiebing Lu

This paper aims to introduce the decomposed harmonic balance finite element method (HBFEM) to decrease the memory requirement in large‐scale computation of the DC‐biasing…

Abstract

Purpose

This paper aims to introduce the decomposed harmonic balance finite element method (HBFEM) to decrease the memory requirement in large‐scale computation of the DC‐biasing magnetic field. Harmonic analysis of the flux density and flux distribution was carried out to investigate the DC biased problem in a laminated core model (LCM).

Design/methodology/approach

Based on the DC bias test on a LCM, the decomposed HBFEM is applied to accurately calculate the DC‐biasing magnetic field. External electric circuits are coupled with the magnetic field in the harmonic domain. The reluctivity matrix is decomposed and the block Gauss‐Seidel algorithm solves each harmonic solution of magnetic field and exciting current sequentially.

Findings

The calculated exciting currents and flux density are compared with that obtained from measurement and time domain finite element analysis, respectively, which demonstrates consistency. The DC bias leads to the significant saturation of the magnetic core and serious distortion of the exciting current. The flux density varies nonlinearly with DC bias excitation.

Research limitations/implications

The harmonic balance method is only applicable in solving the steady state magnetic field. Future improvements in the method are necessary in order to manage the hysteresis effects in magnetic material.

Originality/value

The proposed method to solve the DC biased problem significantly reduces the memory requirement compared to the conventional HBFEM. The decomposed harmonic balance equations are solved efficiently by the block Gauss‐Seidel algorithm combined with the relaxation iterative scheme. An investigation on DC bias phenomena is carried out through the harmonic solution of the magnetic field. The decomposed HBFEM can also be applied to solve 3‐D DC‐biasing magnetic field and eddy current nonlinear problems in a practical power transformer.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Click here to view access options
Article
Publication date: 19 March 2020

Xiaojun Fan, Nanxi Ning and Nianqi Deng

Previous studies have considered customers' psychological responses to intelligent retail technology adoption, but have not considered how technology integration systems…

Downloads
1237

Abstract

Purpose

Previous studies have considered customers' psychological responses to intelligent retail technology adoption, but have not considered how technology integration systems could promote the relationship between retailers and consumers. Based on the Stimulus–Organism–Response framework, this paper proposes a customer engagement model in a fully intelligent retail environment. The concept of the quality of intelligent experience is constructed from the perspective of customer experience, and the effect of the mechanism of smart retail on the customer engagement relationship is discussed.

Design/methodology/approach

Using two surveys, this study analyzes 201 (in study 1) and 321 (in study 2) questionnaires by using structural equation model in partial least square software.

Findings

The analysis shows that the human–machine interaction, intelligent systems and the product content of the quality intelligent experience significantly impact customer engagement on smart retail.

Research limitations/implications

This research was designed for general retail products, without distinguishing between different product types. Thus, it did not consider the moderating effect of product types.

Practical implications

The findings enrich the intelligent retail technology field and provide operable guidance to help smart retailers improve customer relations.

Originality/value

This paper proposes a customer engagement model to describe how technology integration systems promote the relationship between retailers and consumers.

Details

Marketing Intelligence & Planning, vol. 38 no. 7
Type: Research Article
ISSN: 0263-4503

Keywords

Click here to view access options
Article
Publication date: 11 September 2017

Xuebing Dong, Yaping Chang and Xiaojun Fan

Marketers recognize that the internet is crucial in the lives of consumers; thus, they invest money on online advertisements. Using multiple online media primarily…

Abstract

Purpose

Marketers recognize that the internet is crucial in the lives of consumers; thus, they invest money on online advertisements. Using multiple online media primarily influences the message acceptance of consumers. The synergistic effect of online multimedia relies on form, content, and sources of information, and time. The paper aims to discuss these issues.

Design/methodology/approach

A model that reflects the influence of the characteristics of online multimedia on message response through message acceptance is established based on theories of information persuasion, encoding variability, and multiple-source assumption. Based on a survey of 411 online media users, the study applies partial least-squares regression to test the research model.

Findings

The results show that variety of forms, complementary of contents, diversity of sources, and time interval influence message response via message strength. Complementary of contents and diversity of sources affect message response via perceived credibility. Synergy type moderates the relationship between variety of forms and perceived credibility and between diversity of sources and perceived credibility.

Research limitations/implications

The current study mainly tests the effect of these characteristics on message response and the moderating effect of synergy type. Future research can examine the effect of these characteristics on information seeking and consumption behavior and the moderating effect of the cognitive mode of consumers.

Practical implications

This study provides insight into the characteristics of synergy and contributes to the literature on integrated marketing communication. The results provide guidance for practitioners to effectively plan online multimedia practices.

Originality/value

This study explored the influence of the characteristics of online media synergy on message response through message acceptance. The study also discussed the moderating effect of the type of online multimedia synergy.

Details

Online Information Review, vol. 41 no. 5
Type: Research Article
ISSN: 1468-4527

Keywords

Click here to view access options
Article
Publication date: 10 April 2017

Haiyan Qian, Allan Walker and Xiaojun Li

The purpose of this paper is to develop a preliminary model of instructional leadership in the Chinese educational context and explore the ways in which Chinese school…

Downloads
1809

Abstract

Purpose

The purpose of this paper is to develop a preliminary model of instructional leadership in the Chinese educational context and explore the ways in which Chinese school principals locate their instructional-leadership practices in response to traditional expectations and the requirements of recent reforms.

Design/methodology/approach

In-depth interviews were conducted with 22 selected primary school principals in Shenzhen and Guangzhou. A qualitative analysis was conducted to categorize the major leadership practices enacted by these principals.

Findings

An initial model of instructional leadership in China with six major dimensions is constructed. The paper also illustrates and elaborates on three dimensions with the greatest context-specific meanings for Chinese principals.

Originality/value

The paper explores the ways in which Chinese principals enact their instructional leadership in a context in which “the west wind meets the east wind”; that is, when they are required to accommodate both imported reform initiatives and traditional expectations. The paper contributes to the sparse existing research on principals’ instructional leadership in non-western cultural and social contexts.

Details

Journal of Educational Administration, vol. 55 no. 2
Type: Research Article
ISSN: 0957-8234

Keywords

Click here to view access options
Article
Publication date: 26 November 2021

Xiaojun Yao and Masoumeh Azma

This study aims to investigate the impact of skills and knowledge of employees, economic situations of the company, current IT infrastructure, payment fashion, cloud…

Abstract

Purpose

This study aims to investigate the impact of skills and knowledge of employees, economic situations of the company, current IT infrastructure, payment fashion, cloud availability, and cloud privacy and security on the productivity of the human resources in the COVID-19 era.

Design/methodology/approach

Over the past few years, the advent of cloud-assisted technologies has dramatically advanced the Information Technology (IT)-based industries by providing everything as a service. Cloud computing is recognized as a growing technology among companies around the world. One of the most critical cloud applications is deploying systems and organizational resources, especially systems whose deployment costs are high. Manpower is one of the basic and vital resources of the organization, and organizations need an efficient workforce to achieve their goals. But, in the COVID-19 era, human resources' productivity can be reduced due to stress, high labor force, reduced organizational performance and profits, unfavorable organizational conditions, inability to manage and lack of training. Therefore, this study tries to investigate the productivity of human resources in the COVID-19 era. Data were collected from the medium-sized companies through a questionnaire. Distributed questionnaires were conducted on the Likert scale. The model is assessed using the structural equation modeling technique to examine its reliability and validity. The study is a library method and literature review. A case study was conducted through a questionnaire and statistical analysis by SPSS 25 and SMART-PLS.

Findings

Based on the findings, the skills and knowledge of employees, the economic situations of the company, payment fashion, cloud availability and the current IT infrastructures of the company have a positive impact on human resource efficiency in the COVID-19 era. But cloud privacy and security have a negative effect on the productivity of human resources. The findings can be the basis for companies and organizations in the COVID-19 era.

Research limitations/implications

This study has some restrictions that need to be considered in evaluating the obtained results. First, due to the prevalence of Coronavirus, access to information from the companies under study was limited. Second, this research may have overlooked other variables that affect human resource productivity in the COVID-19 era. Prospective researchers can examine the impact of Customer Relationship Management (CRM) and Supply Chain Management (SCM) on the human resource's productivity in the COVID-19 era.

Practical implications

The results of this research are applicable for all companies, their departments and human resources in the COVID-19 era.

Originality/value

In this paper, human resources' productivity in the COVID-19 era is pointed out. The presented new model provides a complete framework for investigating cloud-based enterprise resource planning systems affect the productivity of human resources in the COVID-19 era.

Details

Kybernetes, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0368-492X

Keywords

Click here to view access options
Article
Publication date: 3 January 2020

Caiming Zhang, Xiaojun Xu and Hong Chen

The purpose of this paper is to review the current research on theoretical foundations and applications for CPS from 2017 to 2019 including the applications in library.

Abstract

Purpose

The purpose of this paper is to review the current research on theoretical foundations and applications for CPS from 2017 to 2019 including the applications in library.

Design/methodology/approach

This paper is designed in six parts as Introduction, Literature review, Theoretical foundations of CPS, Applications of CPS, CPS’s application in library and Conclusion. The authors review 70 papers and classify them as the above six parts. The authors collected 70 papers from 2017 to 2019 in the academic databases.

Findings

This paper reviews 70 papers regarding theoretical foundations and applications for CPS from 2017 to 2019 in the academic databases aiming to provide scholars and practitioners with a comprehensive overview. The contents of the papers in each research category are summarized from theoretical foundations and applications including the CPS applications in library.

Originality/value

A main contribution of this review paper is that it summarizes the current state-of-the-art theoretical foundations and applications for CPS and in libraries systematically.

1 – 10 of 35