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1 – 10 of over 4000A. Nicolet, F. Zolla, Y. Ould Agha and S. Guenneau
This paper aims to review various techniques used in computational electromagnetism such as the treatment of open problems, helicoidal geometries and the design of arbitrarily…
Abstract
Purpose
This paper aims to review various techniques used in computational electromagnetism such as the treatment of open problems, helicoidal geometries and the design of arbitrarily shaped invisibility cloaks. This seemingly heterogeneous list is unified by the concept of geometrical transformation that leads to equivalent materials. The practical set‐up is conveniently effected via the finite element method.
Design/methodology/approach
The change of coordinates is completely encapsulated in the material properties.
Findings
The most significant examples are the simple 2D treatment of helicoidal geometries and the design of arbitrarily shaped invisibility cloaks.
Originality/value
The paper provides a unifying point of view, bridging several techniques in electromagnetism.
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Mohammed H. Fahmy, Ahmed Ageeb Elokl and Ramy Abdel-Khalek
The aim of this paper is to investigate the relationship between the ring structure of the twisted partial skew generalized power series ring
Abstract
Purpose
The aim of this paper is to investigate the relationship between the ring structure of the twisted partial skew generalized power series ring
Design/methodology/approach
The authors first introduce the history and motivation of this paper. Secondly, the authors give a brief exposition of twisted partial skew generalized power series ring, in addition to presenting some properties of such structure, for instance, a-rigid ring, a-compatible ring and (G,a)-McCoy ring. Finally, the study’s main results are stated and proved.
Findings
The authors establish the relation between the diameter and girth of the zero-divisor graph of twisted partial skew generalized power series ring
Originality/value
The results of the twisted partial skew generalized power series ring embrace a wide range of results of classical ring theoretic extensions, including Laurent (skew Laurent) polynomial ring, Laurent (skew Laurent) power series ring and group (skew group) ring and of course their partial skew versions.
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Manik Bhowmick, Arup Kumar Rakshit and Sajal Kumar Chattopadhyay
Dref-3 friction spun core yarns produced using staple fibre yarn as the core, e.g. Jute core yarn wrapped with cotton fibre, have poorer mechanical properties compared to the core…
Abstract
Purpose
Dref-3 friction spun core yarns produced using staple fibre yarn as the core, e.g. Jute core yarn wrapped with cotton fibre, have poorer mechanical properties compared to the core yarn itself. The purpose of this study was to understand the structure of such yarns, that will lead to the optimization of fibre, machine and process variables for production of better quality yarn from the Dref-3/3000 machines.
Design/methodology/approach
The Dref spinning trials were conducted following a full factorial design with six variables, all with two operative levels. The Dref-3 friction spun yarn, in which the core is a plied, twisted ring yarn composed of cotton singles and the sheath, formed from the same cotton fibres making the singles, has been examined. The structures have also been studied by using the tracer fibre technique.
Findings
It was observed that rather than depending on the plied core yarn, the tensile properties of the Dref-3 yarn are significantly determined by the parameters those affect the constituent single yarn tensile properties, i.e. the amount of twist and its twist direction, yarn linear density and the sheath fibre proportion used during the Dref spinning in making the final yarn. Further, when the twist direction of single yarn, double yarn and the Dref spinning false twisting are in the same direction, the produced core-sheath yarn exhibits better tensile properties.
Practical implications
The understanding of the yarn structure will lead to optimized production of all staple fibre core Dref spun yarns.
Social implications
The research work may lead to utilization of coarse and harsh untapped natural fibres to the production of value-added textile products.
Originality/value
Though an earlier research has reported the effects of sheath fibre fineness and length on the tensile and bending properties of Dref-3 friction yarn, the present study is the first documented attempt using the tracer fibre technique to understand Dref-3 yarn structure with plied staple fibrous core.
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Mohammad Abbaszadeh, Mohammad Hossein Montazeri and Mojtaba Mirzaie
The purpose of the study is to propose a novel implementation of twisted tape in sinusoidal wavy-walled tubes to enhance the rate of heat transfer without compromising thermal…
Abstract
Purpose
The purpose of the study is to propose a novel implementation of twisted tape in sinusoidal wavy-walled tubes to enhance the rate of heat transfer without compromising thermal efficiency. The study numerically investigates the fluid flow characteristics and analyzes the effect of different geometrical configurations, including wall wave amplitude, tape twist angles and nanoparticle volume fractions, on heat transfer improvement and performance factor.
Design/methodology/approach
This problem is numerically investigated using computational fluid dynamics, and the method is the finite volume method. A two-phase mixture model is used for nanofluid modeling.
Findings
The study investigated the effect of wall waviness, twisted tape, and nanoparticles on forced convective heat transfer and friction factor behavior in laminar pipe flow in three different Reynolds number regimes. The results showed that implementing twisted tape in wavy tubes significantly increased the rate of heat transfer and the performance factor, with the best twist ratio between 90 and 180°. Adding nanoparticles also enhanced heat transfer and performance factor, but to a lesser extent than wavy wall-twisted tape combinations. The study suggests selecting a proper combination of wavy wall and twisted tape at each Reynolds number to achieve an optimum solution.
Originality/value
To the best of the authors’ knowledge, the implementation of the selected passive methods in sinusoidal wavy tubes has not been studied before, and no previous studies have taken into account such a mix of heat transfer improvement techniques.
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Examines the tenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects…
Abstract
Examines the tenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.
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Javad Rahmani Fard and Mohammad Ardebili
The purpose of this paper is to investigate a novel axial flux-switching motor with sandwiched permanent magnet for direct drive electric vehicles (EVs), in which the torque…
Abstract
Purpose
The purpose of this paper is to investigate a novel axial flux-switching motor with sandwiched permanent magnet for direct drive electric vehicles (EVs), in which the torque density is increased and the cogging torque is decreased. For reducing the back-electromotive force (EMF) harmonics and cogging torque, a twisted structure is employed. To improve the dynamic performance of the axial field flux-switching sandwiched permanent magnet (AFFSSPM) motor a space vector modulation-direct torque and flux control scheme is proposed.
Design/methodology/approach
A multi-objective optimization is performed by means of artificial neural network and non-sorting genetic algorithm II to minimize the cogging torque while preserving the average torque.
Findings
A comparative study between two proposed machines and the conventional flux-switching permanent magnet (FSPM) machine is accomplished and the static electromagnetic characteristics are analyzed. It is demonstrated that the proposed model with twisted structure has significantly improved performance over the conventional FSPM machine in back-EMF and efficiency. The proposed controller has a speed loop only and contains neither the current loop nor hysteresis control. The AFFSSPM motor exhibits excellent dynamic performance with this scheme.
Originality value
The axial flux-switching permanent-magnet machine is one of the most efficient machines but the AFFSSPM with sandwiched permanent magnet has not been specially reported to date. Thus in this paper, the authors report on optimal design of an axial flux-switching sandwiched permanent magnet machine for electric vehicles and investigate its dynamic performance.
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Madan Lal Regar, Sujit Kumar Sinha and Bhavna Choubisa
Sewing thread plays an important role in transforming a two-dimensional fabric into three-dimensional garment. Over the years, ring spinning has been dominating the yarn market…
Abstract
Purpose
Sewing thread plays an important role in transforming a two-dimensional fabric into three-dimensional garment. Over the years, ring spinning has been dominating the yarn market because of its consistent performance. Eli-Twist spinning system, a new method of yarn manufacture, provides a product with improved mechanical and physical properties than the conventional ring-spun yarn. It is the process of producing a two-ply compact yarn with improved fibre utilisation. The purpose of this paper is to assess the feasibility of using Eli-Twist yarn as a sewing thread and to compare its performance with conventional thread.
Design/methodology/approach
In this study, regular polyester and Indian cotton were used to produce the Eli-Twist and conventional TFO thread. Three different blends (100 per cent polyester, 50/50 polyester/cotton [P/C] and 100 per cent cotton) were taken to produce three different counts (39.4 tex, 29.5 tex and 23.6 tex) from each composition. The hairiness, tenacity, breaking elongation and coefficient of yarn-to-metal friction of threads were tested and a comparative analysis was made. The seam performance of all the threads was judged by seam strength, seam efficiency and seam elongation.
Findings
The results show that the mass irregularity and imperfections are more or less similar for both types of threads. Eli-Twist sewing thread has shown less friction, less hairiness and higher tensile strength. The Eli-Twist sewing thread was found to be better than the conventional two-ply sewing thread. The seam performance parameters, such as seam strength, seam efficiency and seam elongation of the Eli-Twist thread showed significantly improved performance.
Originality/value
The main concern of this study is delineating the performance of the Eli-Twist sewing thread. No study in this regard has been reported so far. The improved physical and mechanical behaviour of the Eli-Twist yarn has prompted to assess its performance as sewing thread.
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Turbine blisks designed for advanced liquid rocket engine turbopumps are usually of a timed structure with twisted blades, and they can be machined effectively with the electrical…
Abstract
Turbine blisks designed for advanced liquid rocket engine turbopumps are usually of a timed structure with twisted blades, and they can be machined effectively with the electrical discharge machining (EDM) process. After the machining specifications have been designated, the EDM process of a turbopump turbine blisk is discussed, in which the kernel problems are the design of the electrode and the searching of an interference free path to feed the electrode to machine the blisk.
Examines the fourteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects…
Abstract
Examines the fourteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.
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S. Shaikhzadeh Najar, E. Hezavehi, Sh. Hoseini Hashemi and A. Rashidi
The purpose of this paper is to describe a unique approach to investigate the wrinkle force of textile structures in a cylindrical model.
Abstract
Purpose
The purpose of this paper is to describe a unique approach to investigate the wrinkle force of textile structures in a cylindrical model.
Design/methodology/approach
In this research, an apparatus was designed and constructed in order to investigate the torsional and wrinkle behavior of textile structures in a cylindrical model under a different rotational level using data acquisition and micro‐controller systems.
Findings
In the light of research results, the fiber and fabric type, fabric physical and mechanical properties and imposed rotational level significantly contributed to wrinkle characteristics of worsted fabrics. It was noticed that with increase of rotational level, the wrinkle force, and energy increased along weft and warp directions. Wrinkle characteristics along warp direction exhibited greater values than in weft direction.
Originality/value
The study is aimed at determining wrinkle behavior of worsted fabrics under the combined influences of compression and torsional strains.
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