Yaqi Wang, Lin Li and Xiaojun Zhao
The purpose of this paper is to combine the Jiles-Atherton (J-A) hysteresis model with the field separation approach to realize the accurate simulation of dynamic magnetostrictive…
Abstract
Purpose
The purpose of this paper is to combine the Jiles-Atherton (J-A) hysteresis model with the field separation approach to realize the accurate simulation of dynamic magnetostrictive characteristics of silicon steel sheet.
Design/methodology/approach
First, the energy loss of silicon steel sheet is divided into hysteresis loss Why, classical eddy current loss Wed and anomalous loss Wan according to the statistical theory of losses. The Why is calculated by static J-A hysteresis model, Wed and Wan are calculated by the analytical formulae. Then, based on the field separation approach, the dynamic magnetic field is derived. Finally, a new dynamic magnetostrictive model is proposed by means of the quadratic domain rotation model.
Findings
Comparison of simulation and experimental results verifies that the proposed model has high accuracy and strong universality.
Originality/value
The proposed method improves the existing method’s problem of relying on too much experimental data, and the method ensures the calculation accuracy, parameter identification accuracy and engineering practicability. Consequently, the presented work greatly facilitates further explorations and studies on simulation of dynamic magnetostrictive characteristics of silicon steel sheet.
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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…
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.
Details
Keywords
- New member-set
- TEAM Problem 21 Family
- Overall effectiveness
- Harmonics-DC hybrid excitation
- Magnetic flux compensation
- Load-component
- Shielding
- Stray-field loss
- Additional loss
- Material property under complex excitations
- Electromagnetic fields
- Numerical analysis
- Power losses
- Transient analysis
- Material modeling
- Computational electromagnetics
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.
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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 magnetic…
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.
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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 principals…
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.
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Yunlong Jiao, Xiaojun Liu and Kun Liu
Dynamic spreading and wetting on the rough surfaces is complicated, which directly affects the fluxion and phrase transition properties of the fluid. This paper aims to enhance…
Abstract
Purpose
Dynamic spreading and wetting on the rough surfaces is complicated, which directly affects the fluxion and phrase transition properties of the fluid. This paper aims to enhance our knowledge of the mechanism of micro-texture lubrication from interface wettability and provide some guidance for the practical manufacturing of the surfaces with special wettability and better lubrication characteristics.
Design/methodology/approach
The effect of surface topography on the wetting behavior of both smooth and rough hydrophilic surfaces was investigated using a combination of experimental and simulation approaches. Four types of patterns with different topographies were designed and fabricated through laser surface texturing. The samples were measured with a non-contact three-Dimensional (3D) optical profiler and were parameterized based on ISO 25178. Quantitative research on the relevancy between the topography characteristic and wettability was conducted with several 3D topography parameters.
Findings
Results show that for the surfaces with isotropic textures, topography with a small skewness (Ssk) and a large kurtosis (Sku) exhibits better wettability and spreading behavior. For the surfaces with anisotropic textures (smaller texture aspect ratio, Str), dominant textures (such as long groove, rectangle) play a significant guiding role in promoting spreading. In addition, the moving mechanism of the triple contact line and anisotropic spreading were also studied using a computational fluid dynamics simulation. The simulation results have a good adherence with the experimental results.
Originality/value
Most of the surface characterization methods at present remain at a level that is related to geometric description, and the topography parameters are limited to 2D roughness parameters. So in present study, the relevancy between wettability and 3D surface topography parameters is explored. The authors believe that the current work provides a new viewpoint to the relevancy between surface topography and wettability.
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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.
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Emily Carol Blalock, Yangyang Fan and Xiaojun Lyu
The purpose of the paper is to explore Chinese women entrepreneurs’ perceptions of governance within the Shanghai fashion entrepreneurial ecosystem (SFEE) and identify whether…
Abstract
Purpose
The purpose of the paper is to explore Chinese women entrepreneurs’ perceptions of governance within the Shanghai fashion entrepreneurial ecosystem (SFEE) and identify whether policy is effective and inclusive of women entrepreneurs, potential barriers and if implementation is proceeding as planned.
Design/methodology/approach
We used an adaptive qualitative method incorporating a traditional case study utilizing a thematic analysis with a feminist approach to policy analysis. The case study is based on original data from ethnographic practices with a purposive sample of 15 fashion entrepreneurs and triangulated with six political elites within the SFEE.
Findings
The findings indicate that women fashion entrepreneurs perceive effective governance of the SFEE, legitimizing top-down policies and resources as the “right time” for them to be women and entrepreneurs in Shanghai. Entrepreneurs claim “I am human,” asserting gender equality in business but with circumstantial gender roles that can limit access to important resources.
Research limitations/implications
A single industry, the SFEE, limits the generalizability of the findings. Additionally, did the respondents feel comfortable with the truth? True to communist nations, citizens have few opportunities to voice opinions and public dissent is discouraged. However, we took steps to protect anonymity and excluded potentially sensitive questions dealing with geopolitical strife.
Practical implications
The study outlined six SFEE governance challenges and feminist policy responses that will strengthen the future of women’s entrepreneurship. The study can introduce classroom discussions on gender dynamics and entrepreneurship in the global context. This can help students understand the unique challenges women face, such as access to funding, networking opportunities and societal expectations, and how these factors influence the global supply chain.
Originality/value
The case study has several contributions, including a novel entrepreneurial ecosystem (EE) governance framework and the first study to endorse the voice of Chinese women entrepreneurs operating within the Shanghai fashion industry. Further, we contextualize entrepreneurship using anthropological methods. Lastly, the analysis and understanding of SFEE policies have the potential to improve women’s lives, their families and communities.
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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 could…
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
Keywords
Yuxue Luo, Young Un Kim, Lei Li and Xiaojun Tang
This study aims to examine how the parent firm’s foreign direct investment (FDI) motive influences the roles of corporate boards and CEO appointment of foreign subsidiaries in the…
Abstract
Purpose
This study aims to examine how the parent firm’s foreign direct investment (FDI) motive influences the roles of corporate boards and CEO appointment of foreign subsidiaries in the context of emerging market multinational enterprises (EMNEs). Based on the agency and resource dependence theories, foreign subsidiary boards mainly serve two governance roles: an internal role focusing on monitoring subsidiary operations and resource flows with parent firms and an external role aimed at securing local operational effectiveness. This paper specifically examines the composition of foreign subsidiary boards in terms of board independence and expatriate director ratio, and whether the CEO is an expatriate, which reflects the emphasized role.
Design/methodology/approach
This paper collects data on listed foreign subsidiaries of Chinese MNEs between 2005 and 2021. The final sample includes 754 subsidiary-year observations across 20 host economies. The analysis is conducted using Hausman–Taylor estimation.
Findings
This paper finds that strategic asset-seeking FDI motive is associated with a lower expatriate director ratio, a higher independent director ratio and a higher likelihood of hiring nonexpatriate CEOs. In contrast, foreign subsidiaries established with the motive of institutional escape to tax havens result in a higher expatriate director ratio, lower independent director ratio and lower likelihood of hiring nonexpatriate CEOs.
Originality/value
To the best of the authors’ knowledge, this study is the first to explore how FDI motives influence board composition of foreign subsidiaries and appointment of subsidiary CEOs. Theoretically, this paper draws upon agency theory and resource dependence theory to extend their application to foreign subsidiaries of EMNEs. The findings enhance the understanding of international corporate governance.