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Publisher: Emerald   (Total: 335 journals)

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Showing 1 - 200 of 335 Journals sorted alphabetically
A Life in the Day     Hybrid Journal   (Followers: 9)
Academia Revista Latinoamericana de Administración     Open Access   (Followers: 2, SJR: 0.144, h-index: 4)
Accounting Auditing & Accountability J.     Hybrid Journal   (Followers: 30)
Accounting Research J.     Hybrid Journal   (Followers: 25, SJR: 0.26, h-index: 7)
Accounting, Auditing and Accountability J.     Hybrid Journal   (Followers: 19, SJR: 0.88, h-index: 40)
Advances in Accounting Education     Hybrid Journal   (Followers: 14, SJR: 0.514, h-index: 5)
Advances in Appreciative Inquiry     Hybrid Journal   (SJR: 0.124, h-index: 5)
Advances in Autism     Hybrid Journal   (Followers: 7)
Advances in Dual Diagnosis     Hybrid Journal   (Followers: 47, SJR: 0.228, h-index: 2)
Advances in Gender Research     Full-text available via subscription   (Followers: 3, SJR: 0.229, h-index: 7)
Advances in Intl. Marketing     Full-text available via subscription   (Followers: 5, SJR: 0.123, h-index: 11)
Advances in Mental Health and Intellectual Disabilities     Hybrid Journal   (Followers: 60, SJR: 0.29, h-index: 5)
Advances in Mental Health and Learning Disabilities     Hybrid Journal   (Followers: 29)
African J. of Economic and Management Studies     Hybrid Journal   (Followers: 11, SJR: 0.125, h-index: 2)
Agricultural Finance Review     Hybrid Journal  
Aircraft Engineering and Aerospace Technology     Hybrid Journal   (Followers: 179, SJR: 0.391, h-index: 18)
American J. of Business     Hybrid Journal   (Followers: 16)
Annals in Social Responsibility     Full-text available via subscription  
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 10, SJR: 0.215, h-index: 25)
Arts and the Market     Hybrid Journal   (Followers: 9)
Asia Pacific J. of Marketing and Logistics     Hybrid Journal   (Followers: 8, SJR: 0.244, h-index: 15)
Asia-Pacific J. of Business Administration     Hybrid Journal   (Followers: 3, SJR: 0.182, h-index: 7)
Asian Association of Open Universities J.     Open Access  
Asian Education and Development Studies     Hybrid Journal   (Followers: 5)
Asian J. on Quality     Hybrid Journal   (Followers: 2)
Asian Review of Accounting     Hybrid Journal   (Followers: 2, SJR: 0.29, h-index: 7)
Aslib J. of Information Management     Hybrid Journal   (Followers: 24, SJR: 0.65, h-index: 29)
Aslib Proceedings     Hybrid Journal   (Followers: 254)
Assembly Automation     Hybrid Journal   (Followers: 2, SJR: 0.657, h-index: 26)
Baltic J. of Management     Hybrid Journal   (Followers: 3, SJR: 0.354, h-index: 14)
Benchmarking : An Intl. J.     Hybrid Journal   (Followers: 11, SJR: 0.556, h-index: 38)
British Food J.     Hybrid Journal   (Followers: 15, SJR: 0.329, h-index: 35)
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 15, SJR: 0.232, h-index: 4)
Business Process Re-engineering & Management J.     Hybrid Journal   (Followers: 8, SJR: 0.614, h-index: 42)
Business Strategy Series     Hybrid Journal   (Followers: 6, SJR: 0.201, h-index: 6)
Career Development Intl.     Hybrid Journal   (Followers: 16, SJR: 0.686, h-index: 32)
China Agricultural Economic Review     Hybrid Journal   (Followers: 2, SJR: 0.238, h-index: 10)
China Finance Review Intl.     Hybrid Journal   (Followers: 5)
Chinese Management Studies     Hybrid Journal   (Followers: 4, SJR: 0.216, h-index: 12)
Circuit World     Hybrid Journal   (Followers: 15, SJR: 0.346, h-index: 17)
Collection Building     Hybrid Journal   (Followers: 11, SJR: 0.829, h-index: 10)
COMPEL: The Intl. J. for Computation and Mathematics in Electrical and Electronic Engineering     Hybrid Journal   (Followers: 3, SJR: 0.269, h-index: 22)
Competitiveness Review : An Intl. Business J. incorporating J. of Global Competitiveness     Hybrid Journal   (Followers: 6)
Construction Innovation: Information, Process, Management     Hybrid Journal   (Followers: 14, SJR: 0.508, h-index: 8)
Corporate Communications An Intl. J.     Hybrid Journal   (Followers: 7, SJR: 0.703, h-index: 26)
Corporate Governance Intl. J. of Business in Society     Hybrid Journal   (Followers: 7, SJR: 0.309, h-index: 29)
Critical Perspectives on Intl. Business     Hybrid Journal   (Followers: 1, SJR: 0.32, h-index: 15)
Cross Cultural & Strategic Management     Hybrid Journal   (Followers: 8, SJR: 0.356, h-index: 13)
Development and Learning in Organizations     Hybrid Journal   (Followers: 7, SJR: 0.138, h-index: 8)
Digital Library Perspectives     Hybrid Journal   (Followers: 17)
Direct Marketing An Intl. J.     Hybrid Journal   (Followers: 6)
Disaster Prevention and Management     Hybrid Journal   (Followers: 22, SJR: 0.533, h-index: 32)
Drugs and Alcohol Today     Hybrid Journal   (Followers: 129, SJR: 0.241, h-index: 4)
Education + Training     Hybrid Journal   (Followers: 21, SJR: 0.532, h-index: 30)
Education, Business and Society : Contemporary Middle Eastern Issues     Hybrid Journal   (SJR: 0.141, h-index: 10)
Emerald Emerging Markets Case Studies     Hybrid Journal   (Followers: 1)
Employee Relations     Hybrid Journal   (Followers: 6, SJR: 0.435, h-index: 22)
Engineering Computations     Hybrid Journal   (Followers: 4, SJR: 0.387, h-index: 39)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 14, SJR: 0.541, h-index: 28)
Equal Opportunities Intl.     Hybrid Journal   (Followers: 3)
Equality, Diversity and Inclusion : An Intl. J.     Hybrid Journal   (Followers: 14, SJR: 0.239, h-index: 9)
EuroMed J. of Business     Hybrid Journal   (Followers: 1, SJR: 0.145, h-index: 9)
European Business Review     Hybrid Journal   (Followers: 7, SJR: 0.481, h-index: 21)
European J. of Innovation Management     Hybrid Journal   (Followers: 23, SJR: 0.596, h-index: 30)
European J. of Marketing     Hybrid Journal   (Followers: 20, SJR: 0.933, h-index: 55)
European J. of Training and Development     Hybrid Journal   (Followers: 9, SJR: 0.489, h-index: 23)
Evidence-based HRM     Hybrid Journal   (Followers: 6)
Facilities     Hybrid Journal   (Followers: 2, SJR: 0.371, h-index: 18)
Foresight     Hybrid Journal   (Followers: 7, SJR: 0.486, h-index: 20)
Gender in Management : An Intl. J.     Hybrid Journal   (Followers: 17, SJR: 0.359, h-index: 22)
Grey Systems : Theory and Application     Hybrid Journal   (Followers: 1)
Health Education     Hybrid Journal   (Followers: 3, SJR: 0.383, h-index: 17)
Higher Education, Skills and Work-based Learning     Hybrid Journal   (Followers: 44, SJR: 0.172, h-index: 4)
History of Education Review     Hybrid Journal   (Followers: 13, SJR: 0.141, h-index: 2)
Housing, Care and Support     Hybrid Journal   (Followers: 9, SJR: 0.174, h-index: 4)
Human Resource Management Intl. Digest     Hybrid Journal   (Followers: 17, SJR: 0.121, h-index: 6)
Humanomics     Hybrid Journal   (Followers: 2, SJR: 0.14, h-index: 4)
IMP J.     Hybrid Journal  
Indian Growth and Development Review     Hybrid Journal   (SJR: 0.163, h-index: 4)
Industrial and Commercial Training     Hybrid Journal   (Followers: 5, SJR: 0.217, h-index: 14)
Industrial Lubrication and Tribology     Hybrid Journal   (Followers: 6, SJR: 0.322, h-index: 19)
Industrial Management & Data Systems     Hybrid Journal   (Followers: 6, SJR: 0.63, h-index: 69)
Industrial Robot An Intl. J.     Hybrid Journal   (Followers: 3, SJR: 0.375, h-index: 32)
Info     Hybrid Journal   (Followers: 1, SJR: 0.25, h-index: 21)
Information and Computer Security     Hybrid Journal   (Followers: 22)
Information Technology & People     Hybrid Journal   (Followers: 45, SJR: 0.576, h-index: 28)
Interactive Technology and Smart Education     Hybrid Journal   (Followers: 14, SJR: 0.112, h-index: 1)
Interlending & Document Supply     Hybrid Journal   (Followers: 62, SJR: 0.48, h-index: 13)
Internet Research     Hybrid Journal   (Followers: 42, SJR: 1.746, h-index: 57)
Intl. J. for Lesson and Learning Studies     Hybrid Journal   (Followers: 4)
Intl. J. for Researcher Development     Hybrid Journal   (Followers: 9)
Intl. J. of Accounting and Information Management     Hybrid Journal   (Followers: 8, SJR: 0.304, h-index: 7)
Intl. J. of Bank Marketing     Hybrid Journal   (Followers: 8, SJR: 0.515, h-index: 38)
Intl. J. of Climate Change Strategies and Management     Hybrid Journal   (Followers: 14, SJR: 0.416, h-index: 7)
Intl. J. of Clothing Science and Technology     Hybrid Journal   (Followers: 5, SJR: 0.279, h-index: 25)
Intl. J. of Commerce and Management     Hybrid Journal   (Followers: 1)
Intl. J. of Conflict Management     Hybrid Journal   (Followers: 14, SJR: 0.763, h-index: 38)
Intl. J. of Contemporary Hospitality Management     Hybrid Journal   (Followers: 12, SJR: 1.329, h-index: 35)
Intl. J. of Culture Tourism and Hospitality Research     Hybrid Journal   (Followers: 16, SJR: 0.399, h-index: 5)
Intl. J. of Development Issues     Hybrid Journal   (Followers: 10)
Intl. J. of Disaster Resilience in the Built Environment     Hybrid Journal   (Followers: 8, SJR: 0.225, h-index: 7)
Intl. J. of Educational Management     Hybrid Journal   (Followers: 5, SJR: 0.424, h-index: 32)
Intl. J. of Emergency Services     Hybrid Journal   (Followers: 5, SJR: 0.179, h-index: 1)
Intl. J. of Emerging Markets     Hybrid Journal   (Followers: 4, SJR: 0.199, h-index: 5)
Intl. J. of Energy Sector Management     Hybrid Journal   (Followers: 3, SJR: 0.25, h-index: 12)
Intl. J. of Entrepreneurial Behaviour & Research     Hybrid Journal   (Followers: 5, SJR: 0.694, h-index: 28)
Intl. J. of Event and Festival Management     Hybrid Journal   (Followers: 6, SJR: 0.32, h-index: 8)
Intl. J. of Gender and Entrepreneurship     Hybrid Journal   (Followers: 5, SJR: 0.638, h-index: 6)
Intl. J. of Health Care Quality Assurance     Hybrid Journal   (Followers: 9, SJR: 0.352, h-index: 32)
Intl. J. of Health Governance     Hybrid Journal   (Followers: 26, SJR: 0.277, h-index: 15)
Intl. J. of Housing Markets and Analysis     Hybrid Journal   (Followers: 9, SJR: 0.201, h-index: 5)
Intl. J. of Human Rights in Healthcare     Hybrid Journal   (Followers: 9, SJR: 0.13, h-index: 2)
Intl. J. of Information and Learning Technology     Hybrid Journal   (Followers: 7)
Intl. J. of Innovation Science     Hybrid Journal   (Followers: 9, SJR: 0.173, h-index: 5)
Intl. J. of Intelligent Computing and Cybernetics     Hybrid Journal   (Followers: 3, SJR: 0.258, h-index: 10)
Intl. J. of Intelligent Unmanned Systems     Hybrid Journal   (Followers: 4, SJR: 0.145, h-index: 2)
Intl. J. of Islamic and Middle Eastern Finance and Management     Hybrid Journal   (Followers: 8)
Intl. J. of Law and Management     Hybrid Journal   (Followers: 2, SJR: 0.107, h-index: 2)
Intl. J. of Law in the Built Environment     Hybrid Journal   (Followers: 4, SJR: 0.111, h-index: 2)
Intl. J. of Leadership in Public Services     Hybrid Journal   (Followers: 15)
Intl. J. of Lean Six Sigma     Hybrid Journal   (Followers: 7, SJR: 0.562, h-index: 15)
Intl. J. of Logistics Management     Hybrid Journal   (Followers: 12, SJR: 0.998, h-index: 15)
Intl. J. of Managerial Finance     Hybrid Journal   (Followers: 6, SJR: 0.212, h-index: 11)
Intl. J. of Managing Projects in Business     Hybrid Journal   (Followers: 2)
Intl. J. of Manpower     Hybrid Journal   (Followers: 2, SJR: 0.354, h-index: 37)
Intl. J. of Mentoring and Coaching in Education     Hybrid Journal   (Followers: 24)
Intl. J. of Migration, Health and Social Care     Hybrid Journal   (Followers: 10, SJR: 0.261, h-index: 5)
Intl. J. of Numerical Methods for Heat & Fluid Flow     Hybrid Journal   (Followers: 11, SJR: 0.594, h-index: 32)
Intl. J. of Operations & Production Management     Hybrid Journal   (Followers: 17, SJR: 2.198, h-index: 94)
Intl. J. of Organizational Analysis     Hybrid Journal   (Followers: 3, SJR: 0.222, h-index: 11)
Intl. J. of Pervasive Computing and Communications     Hybrid Journal   (Followers: 3, SJR: 0.165, h-index: 9)
Intl. J. of Pharmaceutical and Healthcare Marketing     Hybrid Journal   (Followers: 4, SJR: 0.304, h-index: 12)
Intl. J. of Physical Distribution & Logistics Management     Hybrid Journal   (Followers: 11, SJR: 1.694, h-index: 66)
Intl. J. of Prisoner Health     Hybrid Journal   (Followers: 10, SJR: 0.254, h-index: 10)
Intl. J. of Productivity and Performance Management     Hybrid Journal   (Followers: 6, SJR: 0.785, h-index: 31)
Intl. J. of Public Sector Management     Hybrid Journal   (Followers: 23, SJR: 0.272, h-index: 37)
Intl. J. of Quality & Reliability Management     Hybrid Journal   (Followers: 8, SJR: 0.544, h-index: 63)
Intl. J. of Quality and Service Sciences     Hybrid Journal   (Followers: 2, SJR: 0.133, h-index: 1)
Intl. J. of Retail & Distribution Management     Hybrid Journal   (Followers: 6, SJR: 0.543, h-index: 36)
Intl. J. of Service Industry Management     Hybrid Journal   (Followers: 2)
Intl. J. of Social Economics     Hybrid Journal   (Followers: 9, SJR: 0.227, h-index: 25)
Intl. J. of Sociology and Social Policy     Hybrid Journal   (Followers: 48, SJR: 0.361, h-index: 5)
Intl. J. of Sports Marketing and Sponsorship     Hybrid Journal   (Followers: 1)
Intl. J. of Structural Integrity     Hybrid Journal   (Followers: 2, SJR: 0.325, h-index: 8)
Intl. J. of Sustainability in Higher Education     Hybrid Journal   (Followers: 12, SJR: 0.616, h-index: 29)
Intl. J. of Tourism Cities     Hybrid Journal   (Followers: 2)
Intl. J. of Web Information Systems     Hybrid Journal   (Followers: 6, SJR: 0.208, h-index: 13)
Intl. J. of Wine Business Research     Hybrid Journal   (Followers: 6, SJR: 0.196, h-index: 12)
Intl. J. of Workplace Health Management     Hybrid Journal   (Followers: 11, SJR: 0.358, h-index: 8)
Intl. Marketing Review     Hybrid Journal   (Followers: 16, SJR: 1.076, h-index: 57)
J. for Multicultural Education     Hybrid Journal   (Followers: 3, SJR: 0.124, h-index: 11)
J. of Accounting & Organizational Change     Hybrid Journal   (Followers: 5, SJR: 0.346, h-index: 7)
J. of Accounting in Emerging Economies     Hybrid Journal   (Followers: 7)
J. of Adult Protection, The     Hybrid Journal   (Followers: 15, SJR: 0.291, h-index: 7)
J. of Advances in Management Research     Hybrid Journal   (Followers: 3)
J. of Aggression, Conflict and Peace Research     Hybrid Journal   (Followers: 48, SJR: 0.177, h-index: 9)
J. of Agribusiness in Developing and Emerging Economies     Hybrid Journal   (Followers: 1)
J. of Applied Accounting Research     Hybrid Journal   (Followers: 16, SJR: 0.22, h-index: 5)
J. of Applied Research in Higher Education     Hybrid Journal   (Followers: 51)
J. of Asia Business Studies     Hybrid Journal   (Followers: 3, SJR: 0.115, h-index: 1)
J. of Assistive Technologies     Hybrid Journal   (Followers: 19, SJR: 0.215, h-index: 6)
J. of Business & Industrial Marketing     Hybrid Journal   (Followers: 8, SJR: 0.664, h-index: 48)
J. of Business Strategy     Hybrid Journal   (Followers: 12, SJR: 0.381, h-index: 17)
J. of Centrum Cathedra     Open Access  
J. of Children's Services     Hybrid Journal   (Followers: 5, SJR: 0.167, h-index: 9)
J. of Chinese Economic and Foreign Trade Studies     Hybrid Journal   (Followers: 1, SJR: 0.188, h-index: 4)
J. of Chinese Entrepreneurship     Hybrid Journal   (Followers: 3)
J. of Chinese Human Resource Management     Hybrid Journal   (Followers: 7, SJR: 0.112, h-index: 3)
J. of Communication Management     Hybrid Journal   (Followers: 7, SJR: 0.735, h-index: 6)
J. of Consumer Marketing     Hybrid Journal   (Followers: 18, SJR: 0.613, h-index: 62)
J. of Corporate Real Estate     Hybrid Journal   (Followers: 3, SJR: 0.633, h-index: 5)
J. of Criminal Psychology     Hybrid Journal   (Followers: 118, SJR: 0.13, h-index: 1)
J. of Criminological Research, Policy and Practice     Hybrid Journal   (Followers: 54)
J. of Cultural Heritage Management and Sustainable Development     Hybrid Journal   (Followers: 11, SJR: 0.109, h-index: 5)
J. of Documentation     Hybrid Journal   (Followers: 184, SJR: 0.936, h-index: 50)
J. of Economic and Administrative Sciences     Hybrid Journal   (Followers: 3)
J. of Economic Studies     Hybrid Journal   (Followers: 10, SJR: 0.498, h-index: 26)
J. of Educational Administration     Hybrid Journal   (Followers: 6, SJR: 0.848, h-index: 36)
J. of Engineering, Design and Technology     Hybrid Journal   (Followers: 17, SJR: 0.173, h-index: 10)
J. of Enterprise Information Management     Hybrid Journal   (Followers: 5, SJR: 0.433, h-index: 38)
J. of Enterprising Communities People and Places in the Global Economy     Hybrid Journal   (Followers: 1, SJR: 0.212, h-index: 8)
J. of Entrepreneurship and Public Policy     Hybrid Journal   (Followers: 9)
J. of European Industrial Training     Hybrid Journal   (Followers: 2)
J. of European Real Estate Research     Hybrid Journal   (Followers: 3, SJR: 0.52, h-index: 7)
J. of Facilities Management     Hybrid Journal   (Followers: 3)
J. of Family Business Management     Hybrid Journal   (Followers: 6)
J. of Fashion Marketing and Management     Hybrid Journal   (Followers: 13, SJR: 0.529, h-index: 30)
J. of Financial Crime     Hybrid Journal   (Followers: 342, SJR: 0.158, h-index: 5)
J. of Financial Economic Policy     Hybrid Journal  
J. of Financial Management of Property and Construction     Hybrid Journal   (Followers: 8, SJR: 0.234, h-index: 1)
J. of Financial Regulation and Compliance     Hybrid Journal   (Followers: 9)
J. of Financial Reporting and Accounting     Hybrid Journal   (Followers: 12)
J. of Forensic Practice     Hybrid Journal   (Followers: 49, SJR: 0.225, h-index: 8)
J. of Global Mobility     Hybrid Journal   (Followers: 1)
J. of Global Responsibility     Hybrid Journal   (Followers: 4)
J. of Health Organisation and Management     Hybrid Journal   (Followers: 23, SJR: 0.67, h-index: 27)
J. of Historical Research in Marketing     Hybrid Journal   (Followers: 3, SJR: 0.376, h-index: 8)
J. of Hospitality and Tourism Technology     Hybrid Journal   (Followers: 4, SJR: 0.672, h-index: 10)
J. of Human Resource Costing & Accounting     Hybrid Journal   (Followers: 5)
J. of Humanitarian Logistics and Supply Chain Management     Hybrid Journal   (Followers: 13)

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Journal Cover COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering
  [SJR: 0.269]   [H-I: 22]   [3 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0332-1649
   Published by Emerald Homepage  [335 journals]
  • Analysis and design of electrical machines with material uncertainties in
           iron and permanent magnet
    • Pages: 1326 - 1337
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1326-1337, September 2017.
      Purpose Manufacturing processes, such as laminations, may introduce uncertainties in the magnetic properties of materials used in electrical machines. This issue, together with magnetization errors, can cause serious deterioration in the performance of the machines. Hence, stochastic material models are required for the study of the influences of the material uncertainties. The purpose of this paper is to present a methodology to study the impact of magnetization pattern uncertainties in permanent magnet electric machines. Design/methodology/approach The impacts of material uncertainties on the performances of an interior permanent magnet (IPM) machine were analyzed using two different robustness metrics (worst-case analysis and statistical study). In addition, two different robust design formulations were applied to robust multi-objective machine design problems. Findings The computational analyses show that material uncertainties may result in deviations of the machine performances and cause nominal solutions to become non-robust. Originality/value In this paper, the authors present stochastic models for the quantification of uncertainties in both ferromagnetic and permanent magnet materials. A robust multi-objective evolutionary algorithm is demonstrated and successfully applied to the robust design optimization of an IPM machine considering manufacturing errors and operational condition changes.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:20Z
      DOI: 10.1108/COMPEL-02-2017-0110
       
  • Restricting the design space of multiple-barrier rotors of synchronous
           reluctance machines
    • Pages: 1338 - 1350
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1338-1350, September 2017.
      Purpose This paper aims to propose a numerical methodology to reduce the number of computations required to optimally design the rotors of synchronous reluctance machines (SynRMs) with multiple barriers. Design/methodology/approach Two objectives, average torque and torque ripple, have been simulated for thousands of SynRM models using 2D finite element analysis. Different rotor topologies (i.e. number of flux barriers) were statistically analyzed to find their respective design correlation for high average torque solutions. From this information, optimal geometrical constraints were then found to restrict the design space of multiple-barrier rotors. Findings Statistical analysis of two considered SynRM case studies demonstrated a design similarity between the different number of flux barriers. Upon setting the optimal geometrical constraints, it was observed that the design space of multiple-barrier rotors reduced by more than 56 per cent for both models. Originality/value Using the proposed methodology, optimal geometrical constraints of a multiple-barrier SynRM rotor can be found to restrict its corresponding design space. This approach can handle the curse of dimensionality when the number of geometric parameters increases. Also, it can potentially reduce the number of initial samples required prior to a multi-objective optimization.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:36Z
      DOI: 10.1108/COMPEL-02-2017-0109
       
  • Rigorous time-domain analysis of statistically oriented graphene sheet
           fluctuations
    • Pages: 1351 - 1363
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1351-1363, September 2017.
      Purpose Important statistical variations are likely to appear in the propagation of surface plasmon polariton waves atop the surface of graphene sheets, degrading the expected performance of real-life THz applications. This paper aims to introduce an efficient numerical algorithm that is able to accurately and rapidly predict the influence of material-based uncertainties for diverse graphene configurations. Design/methodology/approach Initially, the surface conductivity of graphene is described at the far infrared spectrum and the uncertainties of its main parameters, namely, the chemical potential and the relaxation time, on the propagation properties of the surface waves are investigated, unveiling a considerable impact. Furthermore, the demanding two-dimensional material is numerically modeled as a surface boundary through a frequency-dependent finite-difference time-domain scheme, while a robust stochastic realization is accordingly developed. Findings The mean value and standard deviation of the propagating surface waves are extracted through a single-pass simulation in contrast to the laborious Monte Carlo technique, proving the accomplished high efficiency. Moreover, numerical results, including graphene’s surface current density and electric field distribution, indicate the notable precision, stability and convergence of the new graphene-based stochastic time-domain method in terms of the mean value and the order of magnitude of the standard deviation. Originality/value The combined uncertainties of the main parameters in graphene layers are modeled through a high-performance stochastic numerical algorithm, based on the finite-difference time-domain method. The significant accuracy of the numerical results, compared to the cumbersome Monte Carlo analysis, renders the featured technique a flexible computational tool that is able to enhance the design of graphene THz devices due to the uncertainty prediction.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:37Z
      DOI: 10.1108/COMPEL-02-2017-0105
       
  • Explicit time integration of eddy current problems using a selective
           matrix update strategy
    • Pages: 1364 - 1371
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1364-1371, September 2017.
      Purpose Discretizing the magnetic vector potential formulation of eddy current problems in space results in an infinitely stiff differential algebraic equation system that is integrated in time using implicit time integration methods. Applying a generalized Schur complement to the differential algebraic equation system yields an ordinary differential equation (ODE) system. This ODE system can be integrated in time using explicit time integration schemes by which the solution of high-dimensional nonlinear algebraic systems of equations is avoided. The purpose of this paper is to further investigate the explicit time integration of eddy current problems. Design/methodology/approach The resulting magnetoquasistatic Schur complement ODE system is integrated in time using the explicit Euler method taking into account the Courant–Friedrich–Levy (CFL) stability criterion. The maximum stable CFL time step can be rather small for magnetoquasistatic field problems owing to its proportionality to the smallest edge length in the mesh. Ferromagnetic materials require updating the reluctivity matrix in nonlinear material in every time step. Because of the small time-step size, it is proposed to only selectively update the reluctivity matrix, keeping it constant for as many time steps as possible. Findings Numerical simulations of the TEAM 10 benchmark problem show that the proposed selective update strategy decreases computation time while maintaining good accuracy for different dynamics of the source current excitation. Originality/value The explicit time integration of the Schur complement vector potential formulation of the eddy current problem is accelerated by updating the reluctivity matrix selectively. A strategy for this is proposed and investigated.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:13Z
      DOI: 10.1108/COMPEL-02-2017-0100
       
  • Optimal design of angular position sensors
    • Pages: 1372 - 1385
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1372-1385, September 2017.
      Purpose This paper aims to investigate the optimal placement and/or orientation of individual sensor elements within integrated angular position sensors, in particular magnetic sensors based on the Hall effect or magnetoresistive effects under consideration of random deviations (variations in the production process, environmental influences, noise) and correlations of these influences. Design/methodology/approach The authors utilize methods from optimal design of experiments to consider random deviations in a system-level model. In this sensor model, they include spatial dependencies of random deviations by means of a Gaussian random field. Based on this, an approach for fast determination of D-optimal designs is presented. Findings The results show that the intuitive and commonly used distributions of magnetic field sensors are actually optimal for the determination of in-phase and quadrature signals in the presence of spatial correlations, provided that the number of field sensors is higher or equal to three. However, in the uncorrelated case, the intuitive solutions are not the only optimal solutions or even not optimal at all. It is found that a restriction to symmetric designs is not necessary; thus, the design space can be extended to allow for further improvements, e.g. miniaturization, of such angular position sensors. Originality/value The proposed approach allows for the fast optimization based on a system model. Correlated random influences are considered by means of a Gaussian random field, which can be obtained either from measurements or from field simulations, e.g. using the finite element method. As this is done before the actual simulation, such evaluations are not needed during the optimization, which allows for very fast solution of the optimization problem. Therefore, the approach is well suited for application-dependent adjustment of sensor designs.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:23Z
      DOI: 10.1108/COMPEL-02-2017-0099
       
  • Harmonic balanced Jiles-Atherton hysteresis implementation for finite
           element simulation
    • Pages: 1386 - 1395
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1386-1395, September 2017.
      Purpose The high calculation effort for accurate material loss simulation prevents its observation in most magnetic devices. This paper aims at reducing this effort for time periodic applications and so for the steady state of such devices. Design/methodology/approach The vectorized Jiles-Atherton hysteresis model is chosen for the accurate material losses calculation. It is transformed in the frequency domain and coupled with a harmonic balanced finite element solver. The beneficial Jacobian matrix of the material model in the frequency domain is assembled based on Fourier transforms of the Jacobian matrix in the time domain. A three-phase transformer is simulated to verify this method and to examine the multi-harmonic coupling. Findings A fast method to calculate the linearization of non-trivial material models in the frequency domain is shown. The inter-harmonic coupling is moderate, and so, a separated harmonic balanced solver is favored. The additional calculation effort compared to a saturation material model without losses is low. The overall calculation time is much lower than a time-dependent simulation. Research limitations/implications A moderate working point is chosen, so highly saturated materials may lead to a worse coupling. A single material model is evaluated. Researchers are encouraged to evaluate the suggested method on different material models. Frequency domain approaches should be in favor for all kinds of periodic steady-state applications. Practical implications Because of the reduced calculation effort, the simulation of accurate material losses becomes reasonable. This leads to a more accurate development of magnetic devices. Originality/value This paper proposes a new efficient method to calculate complex material models like the Jiles-Atherton hysteresis and their Jacobian matrices in the frequency domain.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:25Z
      DOI: 10.1108/COMPEL-02-2017-0098
       
  • Frequency dependent resistance calculation of multiple conductors
    • Pages: 1396 - 1410
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1396-1410, September 2017.
      Purpose The purpose of this paper is to present a method for calculating frequency-dependent resistance when multiple current-carrying conductors are present. Design/methodology/approach Analytical and numerical formulations are presented. Both skin- and proximity-effects are considered in the numerical approach, whereas only skin-effect can be taken into account in analytical equations. The calculation is done using a self-developed integral equation-based field solver. The results are benchmarked using professional software based on the finite element method (FEM). Findings Results from the numerical approach are in agreement with FEM-based software throughout the whole frequency range. Analytical formulations yield unsatisfactory results in higher frequency range. When multiple conductors are mutually relatively close, the proximity-effect has an impact on effective resistance and has to be taken into account. Research limitations/implications The methodology is presented using axially symmetrical conductors. However, the same procedure can be developed for straight conductors as well. Practical implications Presented fast and stable procedure can be used in most electromagnetic devices when frequency-dependent resistance needs to be precisely determined. Originality/value The value of the presented numerical methodology lies in its ability to take both skin- and proximity-effects into account. As conductors are densely packed in most electromagnetic devices, both effects influence the effective resistance. The method can be easily implemented using a self-developed solver and yields satisfactory results.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:34Z
      DOI: 10.1108/COMPEL-02-2017-0093
       
  • Non-iterative object detection methods in electrical tomography for
           robotic applications
    • Pages: 1411 - 1420
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1411-1420, September 2017.
      Purpose This paper aims to investigate the usability of the non-iterative monotonicity approach for electrical capacitance tomography (ECT)-based object detection. This is of particular importance with respect to object detection in robotic applications. Design/methodology/approach With respect to the detection problem, the authors propose a precomputed threshold value for the exclusion test to speed up the algorithm. Furthermore, they show that the use of an inhomogeneous split-up strategy of the region of interest (ROI) improves the performance of the object detection. Findings The proposed split-up strategy enables to use the monotonicity approach for robotic applications, where the spatial placement of the electrodes is constrained to a planar geometry. Additionally, owing to the improvements in the exclusion tests, the selection of subregions in the ROI allows for avoiding self-detection. Furthermore, the computational costs of the algorithm are reduced owing to the use of a predefined threshold, while the detection capabilities are not significantly influenced. Originality/value The presented simulation results show that the adapted split-up strategies for the ROI improve significantly the detection performance in comparison to the traditional ROI split-up strategy. Thus, the monotonicity approach becomes applicable for ECT-based object detection for applications, where only a reduced number of electrodes with constrained spatial placement can be used, such as in robotics.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:35Z
      DOI: 10.1108/COMPEL-02-2017-0092
       
  • An efficient reformulation of a multiscale method for the eddy current
           problem
    • Pages: 1421 - 1429
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1421-1429, September 2017.
      Purpose This paper aims to improve the efficiency of a numerical method to treat the eddy current problem on a laminated material, where using a mesh that resolves each individual laminate would be too computationally expensive. Design/methodology/approach The domain is modeled using a coarse mesh that treats the laminated material as a bulk with averaged properties. The fine-structured behavior is recovered by introducing micro-shape functions in the ansatz space. One such method is analyzed to find further model restrictions. Findings By using a special reformulation, it is possible to eliminate the additional degrees of freedom introduced by the multiscale ansatz at the cost of an additional modeling error that decreases with the laminate thickness. Originality/value The paper gives a computationally more efficient approximate variant to a known multiscale method.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:32Z
      DOI: 10.1108/COMPEL-02-2017-0091
       
  • PCA based state reduction for inverse problems using prior information
    • Pages: 1430 - 1441
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1430-1441, September 2017.
      Purpose Inverse problems are often marked by highly dimensional state vectors. The high dimension affects the quality of the estimation result as well as the computational complexity of the estimation problem. This paper aims to present a state reduction technique based on prior knowledge. Design/methodology/approach Ill-posed inverse problems require prior knowledge to find a stable solution. The prior distribution is constructed for the high-dimensional data space. The authors use the prior distribution to construct a reduced state description based on a lower-dimensional basis, which they derive from the prior distribution. The approach is tested for the inverse problem of electrical capacitance tomography. Findings Based on a singular value decomposition of a sample-based prior distribution, a reduced state model can be constructed, which is based on principal components of the prior distribution. The approximation error of the reduced basis is evaluated, showing good behavior with respect to the achievable data reduction. Owing to the structure, the reduced state representation can be applied within existing algorithms. Practical implications The full state description is a linear function of the reduced state description. The reduced basis can be used within any existing reconstruction algorithm. Increased noise robustness has been found for the application of the reduced state description in a back projection-type reconstruction algorithm. Originality/value The paper presents the construction of a prior-based state reduction technique. Several applications of the reduced state description are discussed, reaching from the use in deterministic reconstruction methods up to proposal generation for computational Bayesian inference, e.g. Markov chain Monte Carlo techniques.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:32Z
      DOI: 10.1108/COMPEL-02-2017-0090
       
  • Stochastic LOD-FDTD method for two-dimensional electromagnetic uncertainty
           problems
    • Pages: 1442 - 1456
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1442-1456, September 2017.
      Purpose Random media uncertainties exhibit a significant impact on the properties of electromagnetic fields that usually deterministic models tend to neglect. As a result, these models fail to quantify the variation in the calculated electromagnetic fields, leading to inaccurate outcomes. This paper aims to introduce an unconditionally stable finite-difference time-domain (FDTD) method for assessing two-dimensional random media uncertainties in one simulation. Design/methodology/approach The proposed technique is an extension of the stochastic FDTD (S-FDTD) scheme, which approximates the variance of a given field component using the Delta method. Specifically in this paper, the Delta method is applied to the locally one-dimensional (LOD) FDTD scheme (hence named S-LOD-FDTD), to achieve unconditional stability. The validity of this algorithm is tested by solving two-dimensional random media problems and comparing the results with other methods, such as the Monte-Carlo (MC) and the S-FDTD techniques. Findings This paper provides numerical results that prove the unconditional stability of the S-LOD-FDTD technique. Also, the comparison with the MC and the S-FDTD methods shows that reliable outcomes can be extracted even with larger time steps, thus making this technique more efficient than the other two aforementioned schemes. Research limitations/implications The S-LOD-FDTD method requires the proper quantification of various correlation coefficients between the calculated fields and the electrical parameters, to achieve reliable results. This cannot be known beforehand and the only known way to calculate them is to run a fraction of MC simulations. Originality/value This paper introduces a new unconditional stable technique for measuring material uncertainties in one realization.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:10Z
      DOI: 10.1108/COMPEL-02-2017-0087
       
  • Efficient circuit representation of eddy-current fields
    • Pages: 1457 - 1473
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1457-1473, September 2017.
      Purpose This paper aims to discuss the relationship between the continued fraction form of the analytical solution in the frequency domain, the orthogonal function expansion and their circuit realization to derive an efficient representation of the eddy-current field in the conducting sheet and wire/cylinder. Effective frequency ranges of representations are analytically derived. Design/methodology/approach The Cauer circuit representation is derived from the continued fraction form of analytical solution and from the orthogonal polynomial expansion. Simple circuit calculations give the upper frequency bounds where the truncated circuit and orthogonal expansion are applicable. Findings The Cauer circuit representation and the orthogonal polynomial expansions for the magnetic sheet in the E-mode and for the wire in the axial H-mode are derived. The upper frequency bound for the Cauer circuit is roughly proportional to N4 with N inductive elements, whereas the frequency bound for the finite element eddy-current analysis with uniform N elements is roughly proportional to N2. Practical implications The Cauer circuit representation is expected to provide an efficient homogenization method because it requires only several elements to describe the eddy-current field over a wide frequency range. Originality/value The applicable frequency ranges are analytically derived depending on the conductor geometry and on the truncation types.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:15Z
      DOI: 10.1108/COMPEL-02-2017-0084
       
  • An integral equation formulation with global series expansion for resonant
           wireless power transfer
    • Pages: 1474 - 1487
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1474-1487, September 2017.
      Purpose The electromagnetic modeling of inductively coupled, resonant wireless power transfer (WPT) is dealt with. This paper aims to present a numerically efficient simulation method. Design/methodology/approach Recently, integral equation formulations have been proposed, using piecewise constant basis functions for the series expansion of the current along the coil wire. In the present work, this scheme is improved by introducing global basis functions. Findings The use of global basis functions provides a stronger numerical stability and a better control over the convergence of the simulation; moreover, the associated computational cost is lower than for the previous schemes. These advantages are demonstrated in numerical examples, with special attention to the achievable efficiency of the power transfer. Practical implications The method can be efficiently used, e.g., in the optimal design of resonant WPT systems. Originality/value The presented computation scheme is original in the sense that global series expansion has not been previously applied to the numerical simulation of resonant WPT.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:26Z
      DOI: 10.1108/COMPEL-02-2017-0079
       
  • Thermo-electric simulation of battery-modules with reduced order modelling
           of linear electrical components
    • Pages: 1488 - 1500
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1488-1500, September 2017.
      Purpose This paper aims to present a fully coupled thermo-electrical finite-element battery model with an applied model-order reduction. The model is used to analyse the thermal design of battery modules during typical drive-cycles of electric vehicles. Design/methodology/approach A model-order reduction is applied, in which the electrical linear bus-bars are analysed in an a-priori step. For these bus-bars, special distributed basis-functions are computed, which make the solution of differential Ohm's law unnecessary during the transient simulation. Furthermore, the distributed basis-functions are used to strongly couple the non-linear battery models, which reduces the iterations needed to simulate them. Findings Altogether, this results in a fast simulation scheme for coupled linear and non-linear electrical components and their thermal behaviour. Originality/value The presented method delivers an innovative approach, on how to systematically minimize the computational effort in a system of linear and non-linear electrical components, while keeping the full three-dimensional information of the original problem.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:30Z
      DOI: 10.1108/COMPEL-02-2017-0075
       
  • Stageless evaluation for a vector Preisach model based on rotational
           operators
    • Pages: 1501 - 1516
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1501-1516, September 2017.
      Purpose This paper aims to present a novel stageless evaluation scheme for a vector Preisach model that exploits rotational operators for the description of vector hysteresis. It is meant to resolve the discretizational errors that arise during the application of the standard matrix-based implementation of Preisach-based models. Design/methodology/approach The newly developed evaluation uses a nested-list data structure. Together with an adapted form of the Everett function, it allows to represent both the additional rotational operator and the switching operator of the standard scalar Preisach model in a stageless fashion, i.e. without introducing discretization errors. Additionally, presented updating and simplification rules ensure the computational efficiency of the scheme. Findings A comparison between the stageless evaluation scheme and the commonly used matrix approach reveals not only an improvement in accuracy up to machine precision but, furthermore, a reduction of computational resources. Research limitations/implications The presented evaluation scheme is especially designed for a vector Preisach model, which is based on an additional rotational operator. A direct application to other vector Preisach models that do not rely on rotational operators is not intended. Nevertheless, the presented methodology allows an easy adaption to similar vector Preisach schemes that use modified setting rules for the rotational operator and/or the switching operator. Originality/value Prior to this contribution, the vector Preisach model based on rotational operators could only be evaluated using a matrix-based approach that works with discretized forms of rotational and switching operator. The presented evaluation scheme offers reduced computational cost at much higher accuracy. Therefore, it is of great interest for all users of the mentioned or similar vector Preisach models.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:28Z
      DOI: 10.1108/COMPEL-02-2017-0073
       
  • Experimental evaluation of numerical errors for multi-physics coupling
           methods using disparate meshes
    • Pages: 1517 - 1525
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1517-1525, September 2017.
      Purpose Multiphysics problems are solved either with monolithic or segregated approaches. For accomplishing contrary discretisation requirements of the physics, disparate meshes are essential. This paper is comparing experimental results of different interpolation methods for a segregated coupling with monolithic approaches, implemented using a global and a local nearest neighbour method. The results show the significant influence of discretisation for multiphysics simulation. Design/methodology/approach Applying disparate meshes to the monolithic as well as the segregated calculation of finite element problems and evaluating the related numerical error is content of the contribution. This is done by an experimental evaluation of a source and a material coupling applied to a multiphysics problem. After an introduction to the topic, the evaluated multiphysics model is described based on two bidirectional coupled problems and its finite element representation. Afterwards, the considered methods for approximating the coupling are introduced. Then, the evaluated methods are described and the experimental results are discussed. A summary concludes this work. Findings An experimental evaluation of the numerical errors for different multiphysics coupling methods using disparate meshes is presented based on a bidirectional electro-thermal simulation. Different methods approximating the coupling values are introduced and challenges of applying these methods are given. It is also shown, that the approximation of the coupling integrals is expensive. Arguments for applying the different methods to the monolithic and the segregated solution strategies are given and applied on the example. The significant influence of the mesh density within the coupled meshes is shown. Since the projection and the interpolation methods do influence the result, a careful decision is advised. Originality/value In this contribution, existing coupling methods are described, applied and compared on their application for coupling disparate meshes within a multiphysics simulation. Knowing their performance is relevant when deciding for a monolithic or a segregated calculation approach with respect to physics dependent contrary discretisation requirements. To the authors’ knowledge, it is the first time these methods are compared with a focus on an application in multiphysics simulations and experimental results are discussed.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:29Z
      DOI: 10.1108/COMPEL-02-2017-0072
       
  • An optimization tool for coaxial magnetic gears
    • Pages: 1526 - 1539
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1526-1539, September 2017.
      Purpose This paper aims to show a complete optimization tool that can be used for the design of coaxial magnetic gears. In the first part, the paper deals with the semi-analytic modelling of these machines and also discusses how to reduce the computational efforts. In the second part, an optimization algorithm is adopted for finding the Pareto optimal geometries. Design/methodology/approach The machine is subdivided into a set of domains according to their physical and geometrical properties, and the potential distribution is found semi-analytically in them under some simplifying hypothesis. A loss estimation is performed for both ferromagnetic and permanent magnet regions. A stochastic differential evolution (DE) algorithm for multi-objective constrained problems is then applied. Findings It is shown that the presented design tool gives results in accordance to finite element method (FEM)-based analysis keeping the advantages of robustness and simplicity of the analytical methods. The DE-based strategy performs well on the magnetic gear optimization problem. Practical implications The proposed tool appears to be a good starting point when designing coaxial magnetic gears. The optimal Pareto points can be used as initial seeds of FEM-based optimizations, resulting in a cheaper computational method with respect to a full FEM optimization. Originality/value This paper takes inspiration from recent works on magnetic gear modelling and completes the design procedure with a suitable efficiency estimation. The paper also shows how to use mature optimization strategies to solve the constrained multi-objective magnetic gear design problem.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:11Z
      DOI: 10.1108/COMPEL-02-2017-0068
       
  • Simulation of electrical machines: a FEM-BEM coupling scheme
    • Pages: 1540 - 1551
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1540-1551, September 2017.
      Purpose Electrical machines commonly consist of moving and stationary parts. The field simulation of such devices can be demanding if the underlying numerical scheme is solely based on a domain discretization, such as in the case of the finite element method (FEM). This paper aims to present a coupling scheme based on FEM together with boundary element methods (BEMs) that neither hinges on re-meshing techniques nor deals with a special treatment of sliding interfaces. While the numerics are certainly more involved, the reward is obvious: the modeling costs decrease and the application engineer is provided with an easy-to-use, versatile and accurate simulation tool. Design/methodology/approach The authors present the implementation of a FEM-BEM coupling scheme in which the unbounded air region is handled by the BEM, while only the solid parts are discretized by the FEM. The BEM is a convenient tool to tackle unbounded exterior domains, as it is based on the discretization of boundary integral equations (BIEs) that are defined only on the surface of the computational domain. Hence, no meshing is required for the air region. Further, the BIEs fulfill the decay and radiation conditions of the electromagnetic fields such that no additional modeling errors occur. Findings This work presents an implementation of a FEM-BEM coupling scheme for electromagnetic field simulations. The coupling eliminates problems that are inherent to a pure FEM approach. In detail, the benefits of the FEM-BEM scheme are: the decay conditions are fulfilled exactly, no meshing of parts of the exterior air region is necessary and, most importantly, the handling of moving parts is incorporated in an intriguingly simple manner. The FEM-BEM formulation in conjunction with a state-of-the-art preconditioner demonstrates its potency. The numerical tests not only reveal an accurate convergence behavior but also prove the algorithm to be suitable for industrial applications. Originality/value The presented FEM-BEM scheme is a mathematically sound and robust implementation of a theoretical work presented a decade ago. For the application within an industrial context, the original work has been extended by higher-order schemes, periodic boundary conditions and an efficient treatment of moving parts. While not intended to be used under all circumstances, it represents a powerful tool in case that high accuracies together with simple mesh-handling facilities are required.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:16Z
      DOI: 10.1108/COMPEL-02-2017-0061
       
  • Rotating- and translating-coil magnetometers for extracting
           pseudo-multipoles in accelerator magnets
    • Pages: 1552 - 1567
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1552-1567, September 2017.
      Purpose The purpose of this paper is to establish the mathematical foundations of magnetic measurement methods based on translating-coil and rotating-coil magnetometers for accelerator magnets and solenoids. These field transducers allow a longitudinal scanning of the field distribution, but require a sophisticated post-processing step to extract the coefficients of the Fourier–Bessel series (known as pseudo-multipoles or generalized gradients) as well as a novel design of the rotating coil magnetometers. Design/methodology/approach Calculating the transversal field harmonics as a function of the longitudinal position in the magnet, or measuring these harmonics with a very short, rotating induction-coil scanner, allows the extraction of the coefficients of a Fourier–Bessel series, which can then be used in the thin lens approximation of the end regions of accelerator magnets. Findings The extraction of the leading term in the Fourier–Bessel series requires the solution of a differential equation by means of a Fourier transform. This yields a natural way to de-convolute the measured distribution of the multipole content. The author has shown that the measurement technique requires iso-parametric coils to avoid interception of the longitudinal field component. The compensation of the main signal cannot be done with the classical arrangement of search coils at different radii, because no easy scaling law exists. A new design of an iso-perimetric induction coil has been found. Research limitations/implications In the literature, it is stated that the pseudo-multipoles can be extracted from field computations or measurements. While this is true for computations, the author shows that the measurement of the field harmonics must be done with iso-parametric coils because otherwise the leading term in the Fourier–Bessel series cannot be extracted. Practical implications The author has now established the theory behind a number of field transducers, such as the moving fluxmeter, the rotational coil scanner and the solenoidal field transducer. Originality/value This paper brought together the known theory of the orthogonal expansion method with the methods and tools for magnetic field measurements to establish a field description in accelerator magnets.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:19Z
      DOI: 10.1108/COMPEL-02-2017-0059
       
  • Inrush current computations using an optimised analytical hysteresis model
    • Pages: 1568 - 1576
      Abstract: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Volume 36, Issue 5, Page 1568-1576, September 2017.
      Purpose The purpose of this paper is the modelling and estimation of inrush currents while energising power devices under no load conditions. An analytical representation of the nonlinear B-H curve serves for considering the hysteresis behaviour in the numerical model. Design/methodology/approach The model is implemented into a standard finite element formulation to compute transient problems. Findings Inrush currents behave like faults in power distribution facilities. Its prior estimation helps to distinguish between operating conditions and faults. Research limitations/implications The magnetic cores may become extremely magnetised. At such high material saturations, the material characteristics are not measurable accurately. Hence, the results depend on the extrapolation of the B-H curves. Originality/value The use of first-order reversal curves within the major hysteresis loops helps in a convenient way to estimate peak and shape of the inrush currents.
      Citation: COMPEL - The international journal for computation and mathematics in electrical and electronic engineering
      PubDate: 2017-09-15T08:09:17Z
      DOI: 10.1108/COMPEL-03-2017-0117
       
 
 
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