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1 – 10 of 446This article re‐examines the theoretical foundation of self‐directed teamwork theory in light of current developments in organizational America, and suggests propositions about…
Abstract
This article re‐examines the theoretical foundation of self‐directed teamwork theory in light of current developments in organizational America, and suggests propositions about the relationship between teamwork and organizational policies such as downsizing. Teamwork is the exercise of creativity and autonomy by employees in pursuit of organizational goals. Effective teamwork requires a sense of trust and inclusion on the part of these employees. Organizational practices such as downsizing and contingent labor can erode this trust. If organizations wish to avoid undermining the financial, productivity and morale gains of teamwork, while observing their broader social responsibilities, they should reconsider their reliance upon downsizing and contingent workforces as a quick and dirty means of achieving cost savings.
A. Al‐Badi, K. El‐Metwally and A. Gastli
This paper aims to study modeling of the nonlinear behavior of the Torus machine back EMF using an adaptive networks fuzzy inference system (ANFIS). The model can be used to study…
Abstract
Purpose
This paper aims to study modeling of the nonlinear behavior of the Torus machine back EMF using an adaptive networks fuzzy inference system (ANFIS). The model can be used to study the steady‐state as well as the dynamic performances of the machine operating as a motor or as a generator.
Design/methodology/approach
Using the universal approximation capability of fuzzy systems the authors designed an ANFIS network to model the nonlinear behavior of the back EMF of the Torus motor. The ANFIS is trained using an actual set machine measurements data to generate the motor back EMF for different operating conditions.
Findings
Simulation results of the ANFIS model of the Torus motor at different loads proved the ability of the algorithm to effectively model the complex electromagnetic behavior of the machine. Such efficient modeling can directly help in improving and optimizing the Torus motor drive system design.
Originality/value
It demonstrates that ANFIS can model the nonlinear behavior of the back EMF of the Torus motor with excellent accuracy.
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Zezhong C. Chen, Zuomin Dong and Geoffrey W. Vickers
The objective of CNC machining is to produce mechanical parts with designed quality most efficiently. To generate CNC tool paths for machining a sculptured part using a three‐axis…
Abstract
The objective of CNC machining is to produce mechanical parts with designed quality most efficiently. To generate CNC tool paths for machining a sculptured part using a three‐axis CNC machine, surface geometry, cutter shape and size, as well as tool path interval and direction need to be considered. In this work, the relation between the direction of a tool motion and cutting efficiency is studied. A new measure of cutting efficiency in three‐axis CNC milling – the length of effective cutting edge (ECE) is introduced. The ECE length is mathematically proven to reach its maximum when the tool cuts a sculptured surface along its steepest tangent direction at the cutter contact point. The steepest tangent direction is thus proven to be the most efficient tool feed direction in three‐axis sculptured part machining. The study identifies tool feed direction as a new control parameter in CNC tool path planning, and forms the foundation for further research on three‐axis tool path generation of sculptured parts.
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SeungGeon Hong, Kang Hyouk Lee and Il Han Park
The purpose of this paper is to propose dot sensitivity analysis of ferromagnetic materials for topology optimization in an axi-symmetric magnetostatic system.
Abstract
Purpose
The purpose of this paper is to propose dot sensitivity analysis of ferromagnetic materials for topology optimization in an axi-symmetric magnetostatic system.
Design/methodology/approach
The dot sensitivity formula for the axi-symmetric system is derived as a closed form using the continuum shape sensitivity formula. The dot sensitivity method is combined with the level set method to perform topology optimization.
Findings
Derived dot sensitivity analysis can generate a ferromagnetic ring torus in a vacant region. Thus, an initial design is not needed for the design material. Two design problems are tested to demonstrate the usefulness of dot sensitivity.
Originality/value
By simultaneously using the shape sensitivity and dot sensitivity, in axi-symmetric magnetic system, the design space is expanded and it includes the interface and the inside of the vacant region. This property can reduce the possibility of local optimum convergence.
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Abdullah Al‐Badi, Adel Gastli and Joseph A. Jervase
The parameters of axial‐field machines are very small compared with the parameters of conventional machines. Different measuring methods are normally used in order to obtain good…
Abstract
Purpose
The parameters of axial‐field machines are very small compared with the parameters of conventional machines. Different measuring methods are normally used in order to obtain good estimates of the machine parameters. These methods are difficult to perform, costly and time consuming. This paper proposes the use of genetic algorithms to predict the self and mutual inductances of a specific type of axial‐field machine, the Torus motor.
Design/methodology/approach
The parameter extraction is reformulated as a search and optimization problem in which the only requirement is a set of values of current versus time and an approximate estimate of the parameters.
Findings
The predicted machine self and mutual inductances are verified by comparing with several measuring methods and excellent agreement is obtained.
Originality/value
Demonstrates that genetic algorithms can predict the self and mutual inductances of the Torus machine automatically with high accuracy.
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Xiao-Shun Zhao, Li Yu, Xue Yang and Si-Yu Zhang
The purpose of this study was to develop a new folding method for modeling complicated folded fabric with surfaces of revolution.
Abstract
Purpose
The purpose of this study was to develop a new folding method for modeling complicated folded fabric with surfaces of revolution.
Design/methodology/approach
Irregular wrinkles and mesh distortions easily appear in the fold modeling of a complex curved surface. Aimed at this key technical problem, the segmentation mapping folding method (SMFM) is proposed in this paper. First, high-precision flattened planes were obtained by using segmentation mapping techniques. Second, the segmented planes were transformed into a folded and continuous geometric model by using matrix transformations. Finally, initial stress was used to modify the geometric folding errors, which ensured agreement with the inflated flexible fabric’s geometry and the original design.
Findings
Compared with the traditional folding method, SMFM has the advantages of good finite-element mesh quality, large radial compression rate, regular folds, etc. The surface area error and the volume error of the inflated single torus established by SMFM were only 1.2 per cent, showing that SMFM has high modeling accuracy. The numerical results of an inflatable re-entry vehicle are presented to demonstrate the reliability, feasibility and applicability of SMFM. Moreover, the stress modification reduced the problems of stress concentration and mesh distortions, improving the accuracy and stability of the numerical calculations.
Originality/value
In this paper, for the first time, a folding method for modeling complicated folded fabric is proposed. This methodology can be used to model the multidimensional compression and regular folds of complex surfaces of revolution that cannot be flattened and to improve the accuracy and stability of the numerical calculations.
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Reza Mirzahosseini, Ahmad Darabi and Mohsen Assili
Consideration of leakage fluxes in the preliminary design stage of a machine is important for accurate determination of machine dimensions and prediction of performance…
Abstract
Purpose
Consideration of leakage fluxes in the preliminary design stage of a machine is important for accurate determination of machine dimensions and prediction of performance characteristics. This paper aims to obtain some equations for calculating the average air gap flux density, the flux density within the magnet and the air gap leakage flux factor.
Design/methodology/approach
A detailed magnetic equivalent circuit (MEC) is presented for a TORUS-type non-slotted axial flux permanent magnet (TORUS-NS AFPM) machine. In this MEC, the leakage flux occurring between two adjacent magnets and the leakage fluxes taking place between the magnet and rotor iron at the interpolar, inner and outer edges of the magnets are considered. According to the proposed MEC and by using flux division law, some equations are extracted. A three-dimensional finite element method (FEM) is used to evaluate the proposed analytical equations. The study machine is a 3.7 kW and 1,400 rpm TORUS-NS AFPM machine.
Findings
The air gap leakage flux factor, the average air gap flux density and the flux density within the magnet are calculated using the proposed equations and FEM. All the results of FEM confirm the excellent accuracy of the proposed analytical method.
Originality/value
The new equations presented in this paper can be applied for leakage flux evaluating purposes.
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Regenerative flow pumps are dynamic machines with the ability to develop high heads at low flow rates. Simplicity, compactness, stable features and low manufacturing costs make…
Abstract
Purpose
Regenerative flow pumps are dynamic machines with the ability to develop high heads at low flow rates. Simplicity, compactness, stable features and low manufacturing costs make them interesting for many applications in industries. The purpose of this study is to present a new method for calculating the flow through regenerative pumps with bucket form blades to predict the performance curves by a cheap and easy-to-use way.
Design/methodology/approach
The analysis was carried out based on the geometric shape of a fluid particle trajectory in a regenerative turbomachine. The fluid particle path was assumed to be a helix wrapped into a torus. Loss models were considered and the results of predictions were compared with computational fluid dynamics (CFD) data.
Findings
The overall trend of performance curves resulted from presented model looked consistent with CFD data. However, there were slight differences in high and low flow coefficients. The results showed that the predicted geometric shape of the flow path with the presented model (a helix wrapped into a torus) was not consistent with CFD results at high flow coefficients. Due to the complexity and turbulence of the fluid flow and errors in the calculation of losses, as well as slip factor, there was a discrepancy between the results of the presented model and numerical simulation, especially in high and low flow coefficients.
Originality/value
The analysis was carried out based on the geometric shape of a fluid particle trajectory in a regenerative turbomachine with bucket form blades. The fluid particle path was assumed to be a helix wrapped into a torus.
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Mohammadreza Baghayipour, Ahmad Darabi and Ali Dastfan
This paper aims to propose an analytical model for the harmonic content no-load magnetic fields and Back electric motive force (EMF) in double-sided TORUS-type non-slotted axial…
Abstract
Purpose
This paper aims to propose an analytical model for the harmonic content no-load magnetic fields and Back electric motive force (EMF) in double-sided TORUS-type non-slotted axial flux permanent magnet (TORUS-NS AFPM) machines with surface-mounted magnets considering the winding distribution and iron saturation effects.
Design/methodology/approach
First, a procedure to calculate the winding distribution with a rectangular cross-section is proposed. The magnetic field distribution and magnetic motive force (MMF) drop due to saturation in iron cores are then exactly extracted in a 2-D analytical model. The consequent influence on air-gap magnetic field and Back EMF are also calculated using a new iterative algorithm. The results are compared with those of the conventional analytical model without saturation, 2-D finite element analysis (FEA) and an experiment on a fabricated prototype machine.
Findings
Unlike the conventional method, the new method yields the no-load magnetic field distributions in air-gap and iron cores and Back EMF very exactly such that the results well match to those of the FEA and experiment.
Originality/value
Unlike the conventional winding factor, the winding distribution is considered here along the both axial and circumferential directions, which improves the accuracy level of results for non-slotted structures with relatively large air-gaps. The magnetic field distribution and MMF drop-in iron parts are also calculated as the basis for exact recalculation of air-gap magnetic field and Back EMF. Because of small computational burden beside superior accuracy, the proposed model can be treated as an accurate and fast substitute for FEA to be used during the design procedure or for predicting the other performance characteristics of TORUS-NS AFPM machines.
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