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Article
Publication date: 6 December 2017

Tanja Hautala, Jaakko Helander and Vesa Korhonen

The purpose of this paper is to review and synthesize the attributes of loose and tight coupling in educational organizations. In addition, it is aimed to determine…

1711

Abstract

Purpose

The purpose of this paper is to review and synthesize the attributes of loose and tight coupling in educational organizations. In addition, it is aimed to determine whether this phenomenon has value and strategies to offer for the current educational administration and research.

Design/methodology/approach

Integrative literature review and content analysis, assisted by Atlas.ti software, were used as the methods of this paper. Review data included 32 articles from peer reviewed journals.

Findings

Conceptual framework of continuum of organizational couplings in educational organizations was generated. Elements of the framework include the features of coupling concepts within the continuum, components of couplings, contributory types of organizational couplings and the elements of leadership and change process with emerging strategies, as well as the element of cultural context. In this paper, elements of continuum of couplings and leadership will be emphasized.

Practical implications

Findings have practical implications for the management and leadership in educational organizations, and for the researchers in the field for future research purposes.

Social implications

Findings have social implications for both teaching staff and administration in educational organizations, by highlighting the attributes of loose and tight coupling, and their connections with leadership, change process and cultural context.

Originality/value

The paper presents a distinctive synopsis of the educational administration literature, in the context of loose and tight coupling, with the time span of four decades.

Details

Journal of Educational Administration, vol. 56 no. 2
Type: Research Article
ISSN: 0957-8234

Keywords

Article
Publication date: 14 August 2007

Cezary Jędryczka

The aim of this paper is to find an accurate model for the finite element analysis of coupled phenomena in the dynamic operation of a magnetorheological clutch (MR CLUTCH).

Abstract

Purpose

The aim of this paper is to find an accurate model for the finite element analysis of coupled phenomena in the dynamic operation of a magnetorheological clutch (MR CLUTCH).

Design/methodology/approach

The rheological properties of magnetorheological fluid (MRF) depend on magnetic field distribution. Therefore, the field‐circuit model of electromagnetic phenomena is coupled with the fluid motion model of MRF. The finite element method and time stepping algorithm are used to solve the examined problem. The eddy currents in massive conducting elements are taken into consideration. In order to include the nonlinearity of ferromagnetic core and non‐linear rheological properties of MRF, the Newton procedure is applied. This procedure is joined with the block‐over relaxation algorithm in order to reduce calculation time.

Findings

The proposed method gives sufficient accuracy of coupled electromagnetic and magnetorheological phenomena analysis. The comparison between measured and calculated clutching torque values shows a good agreement.

Research limitations/implications

Thermal and hysteresis effects are not taken into account.

Originality/value

The presented approach can be useful for designing and optimizing MRF devices with axial symmetry. The accurate finite‐element model of coupled electromagnetic and mechanical phenomena is used as a tool for the analysis of MR device dynamic operation.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 7 March 2008

Laetitia Jacoutot, Emilien Sauvage, Annie Gagnoud, Yves Fautrelle, Patrice Brun and Jacques Lacombe

This paper aims to report on a vitrification process based on direct induction that has been developed by the French Atomic Energy Commission (CEA, France). This process…

Abstract

Purpose

This paper aims to report on a vitrification process based on direct induction that has been developed by the French Atomic Energy Commission (CEA, France). This process is characterized by currents directly induced inside the molten glass and by the cooling of all the crucible walls. In addition, a mechanical stirring device is used to homogenize the molten glass. This paper presents a global modelling of coupled phenomena that take place within the glass bath.

Design/methodology/approach

Electromagnetic, thermal and hydrodynamic phenomena are modelled. The aim of this study is to develop strategy of coupled modelling between these aspects. The thermohydrodynamic calculations are achieved with the Fluent software (distributed by Fluent France) and the electromagnetic aspects are solved by the OPHELIE program based on integral methods (developed in EPM laboratory).

Findings

Two configurations are considered: the first deals with thermal convection in an unstirred bath and the second takes into account the mechanical stirring.

Research limitations/implications

The main limitation is that repartition of the Joule power density within the molten glass is supposed to be not perturbed by the intrusive elements like the thermocouples or the stirrer. This assumption allows us to perform only axisymmetric calculations of induction effect.

Originality/value

This paper present different strategy of coupling the thermohydrodynamic and direct induction phenomena taken place in the molten glass.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 September 2004

Wojciech Szeląg

This paper deals with coupled electromagnetic, hydrodynamic and mechanical motion phenomena in magnetorheological fluid devices. The governing equations of these phenomena

Abstract

This paper deals with coupled electromagnetic, hydrodynamic and mechanical motion phenomena in magnetorheological fluid devices. The governing equations of these phenomena are presented. The numerical implementation of the mathematical model is based on the finite element method and a step‐by‐step algorithm. In order to include non‐linearity, the Newton‐Raphson process has been adopted. A prototype of an electromagnetic brake has been built at the Poznań University of Technology. The method has been successfully adapted to the analysis of this brake. The results of the analysis are presented.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 23 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 8 May 2009

Cezary Jędryczka, Piotr Sujka and Wojciech Szeląg

The purpose of this paper is to elaborate upon the mathematical model of coupled electromagnetic, fluid dynamic and motion phenomena that will allow for investigation of…

Abstract

Purpose

The purpose of this paper is to elaborate upon the mathematical model of coupled electromagnetic, fluid dynamic and motion phenomena that will allow for investigation of the magnetic hysteresis influence on the axial symmetry magnetorheological fluid (MRF) clutch operation.

Design/methodology/approach

To solve the partial differential equations describing magnetic vector and fluid velocity potential distributions in axial symmetry MRF electromechanical transducers the finite‐element methods have been applied. To solve model equations in the time domain, the time stepping method have been adopted. To introduce magnetic hysteresis phenomenon to presented approach the Jiles‐Atherton model have been applied. The physical properties of MRFs have been modeled by means of the Bingham model. Owing to high nonlinearity of the considered problem to solve obtained matrix equations systems the iterative Newton‐Raphson combined with the block over relaxation method have been applied.

Findings

The proposed model of coupled phenomena and the elaborated algorithm for solving the nonlinear model equations can be successfully applied in the analysis of transients in the MRF transducers taking fluid dynamics and magnetic hysteresis into account. Comparison of the measured and calculated clutch characteristics proves the model accuracy. Moreover, it has been shown that the residual magnetic flux density of the ferromagnetic core has significant impact on both to yield stresses forming in MRFs as well as the torque in disengagement clutch operation.

Originality/value

Development of the method for analysis of transients electromagnetic and fluid flow phenomena in MRF transducers taking magnetic hysteresis, electric circuits and motion into account. The presented approach is universal and can be successfully applied in other types of MRF electromechanical transducers such as clutch, brakes, rotary and linear dampers.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 9 January 2007

Z. Makni, M. Besbes and C. Marchand

This paper aims to describe a CAD tool of permanent magnet electric machines. The software tool is operational from the first design phases and allows to study coupled phenomena.

Abstract

Purpose

This paper aims to describe a CAD tool of permanent magnet electric machines. The software tool is operational from the first design phases and allows to study coupled phenomena.

Design/methodology/approach

The described design methodology is based on the association of analytical and numerical approaches. A coupled electromagnetic‐thermal model is used for the analytical study. The numerical one uses the finite element method.

Findings

The sequential implementation of the two approaches highlights their complementarities and improves the time consuming and the reliability of the design process. The thermal coupling allows to anticipate the overheating of the machine and to take it into account in the design process.

Research limitations/implications

The simplifying assumptions made in the analytical model degrade the accuracy of temperature calculation.

Practical implications

This is a useful tool for electric machines manufacturer planning to obtain a fast and reliable solution in response to datasheet specifications.

Originality/value

This paper describes a multidisciplinary design methodology which is performed by coupling methods and software tools at the aim to take advantage of each one.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 24 July 2007

Valentina A. Salomoni, Gianluca Mazzucco and Carmelo E. Majorana

This paper seeks to analyse 3D growing concrete structures taking into account the phenomenon of body accretion, necessary for the simulation of the construction sequence…

Abstract

Purpose

This paper seeks to analyse 3D growing concrete structures taking into account the phenomenon of body accretion, necessary for the simulation of the construction sequence, and carbon dioxide attack.

Design/methodology/approach

A typical 3D segmental bridge made of precast concrete is studied through a fully coupled thermo‐hygro‐mechanical F.E. model. The durability of the bridge is evaluated and carbonation effects are considered. Creep, relaxation and shrinkage effects are included according to the theory developed in the 1970s by Bažant for concretes and geomaterials; the fluid phases are considered as a unique mixture which interacts with a solid phase. The porous material is modelled using n Maxwell elements in parallel (Maxwell‐chain model).

Findings

First, calibration analyses are developed to check the VISCO3D model capabilities for predicting carbonation phenomena within concrete and the full 3D structure is modelled to further assess the durability of the bridge under severe conditions of CO2 attack.

Originality/value

The adopted numerical model accounts for the strong coupling mechanisms of CO2 diffusion in the gas phase, moisture and heat transfer, CaCO3 formation and the availability of Ca(OH)2 in the pore solution due to its transport by water movement. Additionally, the phenomenon of a sequential construction is studied and numerically reproduced by a sequence of “births” for the 3D finite elements discretizing the bridge. The fully coupled model is here extended to 3D problems for accreting bodies (as segmental bridges) in order to gather the effects of multi‐dimensional attacks of carbon dioxide for such structures.

Details

Engineering Computations, vol. 24 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 15 June 2010

A. Mauro, F. Arpino, N. Massarotti and P. Nithiarasu

The purpose of this paper is to describe two‐ and three‐dimensional numerical modelling of solid oxide fuel cells (SOFCs) by employing an accurate and stable fully matrix…

Abstract

Purpose

The purpose of this paper is to describe two‐ and three‐dimensional numerical modelling of solid oxide fuel cells (SOFCs) by employing an accurate and stable fully matrix inversion free finite element algorithm.

Design/methodology/approach

A general and detailed mathematical model has been developed for the description of the coupled complex phenomena occurring in fuel cells. A fully matrix inversion free algorithm, based on the artificial compressibility (AC) version of the characteristic‐based split (CBS) scheme and single domain approach have been successfully employed for the accurate and efficient simulation of high temperature SOFCs.

Findings

For the first time, a stable fully explicit algorithm has been applied to detailed multi‐dimensional simulation transport phenomena, coupled to chemical and electrochemical reactions, in fluid, porous and solid parts of a SOFC. The accuracy of the present results has been verified via comparison with experimental and numerical data available in the literature.

Originality/value

For the first time, thanks to a stabilization analysis conducted, the AC‐CBS algorithm has been successfully used to numerically solve the generalized model, applied in this paper to describe transport phenomena through free fluid channels and porous electrodes of SOFCs, without the need of further conditions at the fluid‐electrode interface.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 20 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 1 June 1996

Nicolaos J. Siakavellas

Solves a coupled electromagnetic‐mechanical problem ‐ that of a cantilevered conductive plate in crossed steady and time‐varying magnetic fields ‐ by using a…

Abstract

Solves a coupled electromagnetic‐mechanical problem ‐ that of a cantilevered conductive plate in crossed steady and time‐varying magnetic fields ‐ by using a semi‐analytical method and an eddy current model. Assumes that the magnetic flux variation induces two electromotive forces to the plate; one due to the time‐varying magnetic field and the other to the plate movement in the steady magnetic field. Considers two equivalent LR circuits and notes that the superposition of their currents yields the total circulating current in the plate. Couples this electromagnetic model to the one‐dimensional beam bending model, adopted for the structural analysis of the problem and derives the system of the coupled electromagnetic‐mechanical equations. Calculates analytically some of the parameters involved in these equations so that the numerical computation of the remaining unknowns is very rapid. Concludes that the results are in agreement with the experiment and with results obtained by numerical methods treating, in three dimensions, the electromagnetic aspects of the problem. Notes that the fully numerical methods are very much CPU time consuming.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 15 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 September 2003

Bernard Paya, Virgiliu Fireteanu, Alexandru Spahiu and Christophe Guérin

This paper presents the results of a series of tests made in order to validate the magneto‐thermal module of the new FLUX3D v3.40. The tool was conceived to solve the…

Abstract

This paper presents the results of a series of tests made in order to validate the magneto‐thermal module of the new FLUX3D v3.40. The tool was conceived to solve the coupled problems of electromagnetic and thermal phenomena. The solving method of the program considers a thermal‐transient problem during a certain period of time and it solves, at each time step, the thermal and electromagnetic equations (in quasi‐stationary magneto‐harmonic formulation), alternatively. We have modelled the inductive longitudinal welding of steel pipes. The results of 3D simulations are compared with measurements on a laboratory device.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 22 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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