Search results

1 – 10 of over 4000
Article
Publication date: 25 May 2022

Meng Yuan, Yinghui Ji and Fan Yang

The purpose of this paper is to analyze the characteristics of the factors influencing the effect of magnetic levitation, including the impedance angle of the levitated…

Abstract

Purpose

The purpose of this paper is to analyze the characteristics of the factors influencing the effect of magnetic levitation, including the impedance angle of the levitated coil, number of turns, material parameter, frequency of excitation and geometric parameters. The final purpose is to provide approaches to increasing the levitation effect.

Design/methodology/approach

Some design principles and strategies for levitation systems are suggested, such as selecting the number of turns of the levitated coil, choosing the frequency of excitation considering the saturation phenomenon of levitation force against frequency and deciding the section area of the excitation coil and its ratio of height and thickness.

Findings

The magnetic force is not always repulsive in a cycle. Therefore, the key approach to increasing the levitation is to increase the period when the force is repulsive and decrease the time when attractive. The impedance angle of the equivalent circuit of the levitated coil determines the ratio of the two periods, and the larger the angle, the longer the repulsion period. A valuable finding is that a saturation situation exists between the levitation force and frequency; that is, when the frequency increases to a certain value, the increasing degree of force tends to decrease as the frequency increases.

Originality/value

Some influential characteristics were found in some factors against the effect of the levitation system, which is beneficial for improving the efficiency of systems. For example, owing to the saturation phenomenon of the frequency, it is useless to continue increasing the frequency and the copper-levitated coil does not bring much greater force effectiveness than the aluminum coil.

Details

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

Keywords

Article
Publication date: 31 May 2022

Liang Xuan and Zheng Xu

Gradient coils designed by conventional target field methods usually have a complex physical structure and these methods are not convergent for complex routing area…

Abstract

Purpose

Gradient coils designed by conventional target field methods usually have a complex physical structure and these methods are not convergent for complex routing area problems. This study aims to design a multi-coil (MC) gradient system arranged on a complex routing area including two cylindrical surfaces with different radii for a head magnetic resonance imaging scanner.

Design/methodology/approach

A MC system model is established. In this model, the sub-coils are evenly distributed on two cylindrical wiring surfaces, and the radii of coils are the same on one cylindrical surface. With the target magnetic field set, the currents in every individual coil are solved by constrained least-squares fitting based on the Levenberg–Marquardt method.

Findings

The magnetic field nonlinearity generated by designed coils is validated as 4.50% and 3.57% for X-gradient coil and Z-gradient coil, respectively, which satisfy the mainstream nonlinearity standards. The analysis of the optimization results indicates that hardware requirements can be considerably reduced by connecting coils with the same currents in series.

Originality/value

High-linearity gradient magnetic fields are generated on complex routing areas by adopting the MC structure. In addition, the requirements for current sources and amplifiers are considerably reduced.

Details

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

Keywords

Article
Publication date: 10 May 2019

Shogo Fujita and Hajime Igarashi

The tensor complex permeability of a multi-turn coil with elliptic cross-section is analytically expressed. In field analysis, a multi-turn coil can be modeled by the…

Abstract

Purpose

The tensor complex permeability of a multi-turn coil with elliptic cross-section is analytically expressed. In field analysis, a multi-turn coil can be modeled by the uniform material that has the present tensor complex permeability. It is shown that the frequency characteristic of the present tensor complex permeability is in good agreement with that evaluated by finite element method applied to a unit cell of the multi-turn coil region.

Design/methodology/approach

The authors introduce a new method to evaluate the complex permeability of a multi-turn rectangular coil. To obtain the complex permeability of a rectangular coil in a closed form, it is approximated as an elliptic coil. Because the rectangular coil has different complex permeabilities in the vertical and horizontal directions, the complex permeability have to be defined in a tensor form. It suffices to discretize the coil region into rather coarse finite elements without considering the skin depth in contrast to the conventional finite element method.

Findings

The proposed method is shown to give the impedance of multi-turn coils which is in good agreement with results obtained by the conventional finite element (FE) analysis. By extending the proposed approach, the authors can easily perform 3D FE analysis without difficulty in discretization of the coil region with fairly fine finite elements. Moreover, they found that the approximation of rectangular coils as the elliptic coils is valid for analysis of quasi-static fields using this homogenization method.

Originality/value

The novelty of this study is in the approximation of the rectangular coils with elliptic coils, and the complex permeability for them is formulated here in a closed form. The proposed formula includes that for the round coils. Using the present method, the authors analyze the rectangular coils without fine discretization.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 38 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 6 July 2015

Mihaela Cretu and Dan Doru Micu

– The purpose of this paper is to evaluate the response of the spinal cord, the transmembrane potential, during lumbar magnetic stimulation, using a figure of eight coil.

Abstract

Purpose

The purpose of this paper is to evaluate the response of the spinal cord, the transmembrane potential, during lumbar magnetic stimulation, using a figure of eight coil.

Design/methodology/approach

In order to obtain a precise stimulation of the spinal cord and not the nearby nervous fibres, the coil from the electric circuit of the magnetic stimulator is optimized. The new proposed design is based on the turns’ placement inside the coil, the number of turns required to produce activation. Once the coil configuration is established, the paper addresses other issues that need to be solved: reducing power consumption (the low efficiency of power transfer from the coil to the tissue is a major drawback) and reducing coil heating.

Findings

The traditional commercial coils, used for magnetic stimulation in some preliminary experiments, had proved their inability to specifically stimulate the target tissue, without activating the surrounding areas and the low efficiency of power transfer from the coil to the nervous tissue. A more realistic modelling of the stimulating coil, based on the distribution of turns inside the coil can lead to directly stimulation of the spinal cord, during lumbar magnetic stimulation.

Practical implications

If the electrical circuit of the magnetic stimulator is improved, the direct stimulation of the spinal cord is obtained; so, this technique could facilitate functional motor activities, including standing and stepping in paralyzed people, without requiring implantation of electrodes like in electrical stimulation.

Originality/value

The authors underlined that the spinal cord stimulation can be achieved by magnetic stimulation, only if the parameters of the stimulator circuit are optimized. Therefore an original and realistic modelling of the inductive coil was proposed based on number and turns’ distribution within the coil. The coil is designed so that reducing the excessive heating makes it difficult in obtaining a more frequent repetition of stimulus.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 December 1976

AMERICUS

Industry growth in the field of coil coatings has been impressive as several of the articles abstracted below attest. The advantages inherent in coil coatings from the…

Abstract

Industry growth in the field of coil coatings has been impressive as several of the articles abstracted below attest. The advantages inherent in coil coatings from the points of view of economy, adaptability to automation, and adaptability of the final product to fabrication are impressive ones that industry is taking full advantage of. There are, to be sure, some problems associated with the use of precoated steel, such as destruction of the coating during weldability, but techniques have been devised, including mechanical fastening, to circumvent such problems.

Details

Pigment & Resin Technology, vol. 5 no. 12
Type: Research Article
ISSN: 0369-9420

Article
Publication date: 27 November 2019

Suqi Liu and Jianping Tan

This paper aims to find an approach that achieves constant output power and transfer efficiency in an open space, such as charging pads.

Abstract

Purpose

This paper aims to find an approach that achieves constant output power and transfer efficiency in an open space, such as charging pads.

Design/methodology/approach

In this study, a topology of the five-coil system including two transmitting coils is presented. Also, in a fixed-frequency mode and an open space, this study focuses on the two transmitting coils to achieve the uniform magnetic field and ultimately, attain the constant output power and transfer efficiency.

Findings

In a fixed-frequency mode and an open space, the constant output power and transfer efficiency is then achieved in experiments by inserting the relay loop into the uniform magnetic field.

Practical implications

An approach that achieves constant output power and transfer efficiency in an open space. The topology of the five-coil magnetically coupled resonant-wireless power transfer (MCR-WPT) system shows prospective value for various applications, which could be used at designing of wireless battery charger dedicated for cars or mobile phones.

Originality/value

By comparing the simulation and experimental results, the topology can be optimized in the transmission performance by itself. By doing so, the constant output power and transfer ef?ciency are achieved in the constant frequency mode.

Details

Circuit World, vol. 46 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 13 July 2010

Sanjay Jayaram

Recent advances in nano and picosatellite missions and future such missions require three axis attitude control system hardware for attitude control purposes. A simple…

Abstract

Purpose

Recent advances in nano and picosatellite missions and future such missions require three axis attitude control system hardware for attitude control purposes. A simple, cost effective, yet an efficient devise that is used for active attitude control is magnetic torquer coil. The purpose of this paper is to describe the design and fabrication of a template to manufacture magnetic torquer coils of varying sizes and shapes.

Design/methodology/approach

Details about the development of the template design, analysis, and fabrication are discussed. The development status of the system is outlined and the working prototype of the device is described and some preliminary test results are given.

Findings

A fully functional prototype of the template has been developed and testing has been conducted that demonstrated the effectiveness of the device. Magnetic torquer coils of varying sizes were fabricated and tested. A finite element analysis was performed by modeling the characteristics of the fabricated coils to determine thermally induced stresses and deformations during its space operations.

Practical implications

The paper illustrates and demonstrates an effective application of torquer coil template in the satellite fabrication industry. The benefits from the approach are generally applicable to any future university and industry missions using picosatellite technology.

Originality/value

The designed template satisfied all the constraints and requirements. Furthermore, its advantages include scalability, modularity, and its capability to fabricate magnetic torquer coils of varying sizes and shapes.

Details

Journal of Engineering, Design and Technology, vol. 8 no. 2
Type: Research Article
ISSN: 1726-0531

Keywords

Article
Publication date: 4 July 2016

Hua Li and Wolfgang Rucker

The purpose of this paper is to present an accurate and efficient hybrid method for the calculation of the inductance of a coil and its inductance change due to deformed…

Abstract

Purpose

The purpose of this paper is to present an accurate and efficient hybrid method for the calculation of the inductance of a coil and its inductance change due to deformed turns using numerical methods.

Design/methodology/approach

The paper opted for finite element method coupled with analytical method (FCA) to accurately calculate the inductance of a coil, which is used as reference value. An algorithm with a power function is presented to approximate the partial inductance matrix with the purpose of obtaining the percentage change of the inductance due to deformed turns by using the partial element equivalent circuit (PEEC) with an approximated model and an optimization process. The presented method is successfully validated by the numerical results.

Findings

The paper provides a systematic investigation of the inductance of an arbitrary shaped coil and shows how to accurately and efficiently evaluate the inductance change of a coil due to its deformed turns. It suggests that the inductance of a coil can be accurately calculated by using FCA and its percentage change due to deformed turns can be efficiently calculated by using the PEEC_Approximation.

Research limitations/implications

As this research is for the magnetostatics, the skin- and proximity-effects have not been taken into account.

Practical implications

The paper includes implication for the worst-case analysis of the coil’s inductance due to mechanical damage or manufacturing tolerance.

Originality/value

This paper fulfills an identified need to study how the inductance change of a coil can be obtained accurately and efficiently.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 20 January 2020

Suqi Liu and Yuping Liu

The impedance compensation approaches have been adopted to achieve the maximum output power and transfer efficiency in many magnetic coupling resonance wireless power…

Abstract

Purpose

The impedance compensation approaches have been adopted to achieve the maximum output power and transfer efficiency in many magnetic coupling resonance wireless power transfer projects. However, it remains a challenge to obtain the constant output power and transfer efficiency in a fixed-frequency mode during variations in transfer distance and orientation of the coils. In this paper, using two series transmitting coils to achieve the constant output power and transfer efficiency is used.

Design/methodology/approach

First, the circuit model is established and transfer characteristics are studied. Second, using the two series transmitting coils to achieve the constant output power and transfer efficiency is investigated. Finally, the experimental system is designed; it can optimize the transfer performances by itself; the constant output power and transfer efficiency are achieved in the fixed-frequency mode.

Findings

When the receiving coil moves between the two series transmitting coils, the tolerance of the output power and transfer efficiency is less than 5 per cent.

Research limitations/implications

When a receiving coil is placed between the two series transmitting coils, there are space limits. The receiving coil only shifts between the two transmitting coils.

Practical implications

However, the rail guide vehicle may achieve constant output power and transfer efficiency when it moves on the rail guide. So, this topology may provide a practical solution.

Originality/value

In this research, the three-coil MCR-WPT system including two series transmitting coils is presented. In a fixed-frequency mode, the constant output power and transfer efficiency is achieved in experiments during variations in transfer distance and orientation of the coils. The fluctuation of the output power and transfer efficiency is less than 5 per cent.

Article
Publication date: 17 October 2022

Fengwei Jing, Mengyang Zhang, Jie Li, Guozheng Xu and Jing Wang

Coil shape quality is the external representation of strip product quality, and it is also a direct reflection of strip production process level. This paper aims to…

Abstract

Purpose

Coil shape quality is the external representation of strip product quality, and it is also a direct reflection of strip production process level. This paper aims to predict the coil shape results in advance based on the real-time data through the designed algorithm.

Design/methodology/approach

Aiming at the strip production scale and coil shape application requirements, this paper proposes a strip coil shape defects prediction algorithm based on Siamese semi-supervised denoising auto-encoder (DAE)-convolutional neural networks. The prediction algorithm first reconstructs the information eigenvectors using DAE, then combines the convolutional neural networks and skip connection to further process the eigenvectors and finally compares the eigenvectors with the full connect neural network and predicts the strip coil shape condition.

Findings

The performance of the model is further verified by using the coil shape data of a steel mill, and the results show that the overall prediction accuracy, recall rate and F-measure of the model are significantly better than other commonly used classification models, with each index exceeding 88%. In addition, the prediction results of the model for different steel grades strip coil shape are also very stable, and the model has strong generalization ability.

Originality/value

This research provides technical support for the adjustment and optimization of strip coil shape process based on the data-driven level, which helps to improve the production quality and intelligence level of hot strip continuous rolling.

Details

Assembly Automation, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0144-5154

Keywords

1 – 10 of over 4000