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21 – 30 of over 2000Mario A. Rodriguez Barrera and Walter Pereira Carpes Jr
The purpose of this paper is to present the results of a particle swarm optimization (PSO) method applied in the design of a square-loop frequency selective surface (FSS) via the…
Abstract
Purpose
The purpose of this paper is to present the results of a particle swarm optimization (PSO) method applied in the design of a square-loop frequency selective surface (FSS) via the equivalent circuit model (ECM), considering the dielectric effective permittivity as a variable in the optimization problem.
Design/methodology/approach
In the optimization process considered, besides the FSS square loop geometric parameters, the thickness and relative permittivity of dielectric material used as support are included as variables in the search space, using for this a model of dielectric effective permittivity introduced by the authors in a previous work.
Findings
Square loops were designed and the obtained results were compared with designs reported in literature for applications in wireless local area network and long-term evolution 4G systems. The low computational cost is remarkable as well as the acceptable accuracy obtained with the proposed approach. The PSO method results were implemented with the ECM and compared with those obtained via Ansys – high frequency structure simulator commercial software simulations.
Originality/value
The lack of a model of dielectric effective permittivity for the ECM causes a restricted search space in the stochastic FSS design process limited to only geometric parameters, as it is reported in the available literature. The proposed approach simplifies and makes more flexible the design process, and allows guiding the FSS design to unit cell surface and/or dielectric thickness of small dimensions.
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This paper aims to analyze soil electrical properties based on fractional calculus theory due to the fact that the frequency dependence of soil electrical parameters at high…
Abstract
Purpose
This paper aims to analyze soil electrical properties based on fractional calculus theory due to the fact that the frequency dependence of soil electrical parameters at high frequencies exhibits a fractional effect. In addition, for the fractional-order formulation, this paper aims to provide a more accurate numerical algorithm for solving the fractional differential equations.
Design/methodology/approach
This paper analyzes the frequency-dependence of soil electrical properties based on fractional calculus theory. A collocation method based on the Puiseux series is proposed to solve fractional differential equations.
Findings
The algorithm proposed in this paper can be used to solve fractional differential equations of arbitrary order, especially for 0.5th-order equations, obtaining accurate numerical solutions. Calculating the impact response of the grounding electrode based on the fractional calculus theory can obtain a more accurate result.
Originality/value
This paper proposes an algorithm for solving fractional differential equations of arbitrary order, especially for 0.5th-order equations. Using fractional calculus theory to analyze the frequency-dependent effect of soil electrical properties, provides a new idea for ground-related transient calculation.
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Renato Iovine, Luigi La Spada and Lucio Vegni
– In this contribution, the aim is to present a nanoparticle device, operating in the visible regime based on the localized surface plasmon resonance (LSPR) phenomenon.
Abstract
Purpose
In this contribution, the aim is to present a nanoparticle device, operating in the visible regime based on the localized surface plasmon resonance (LSPR) phenomenon.
Design/methodology/approach
The nanoparticle electromagnetic properties are evaluated by a new analytical model and compared to the results obtained by numerical analysis.
Findings
A near-field enhancement is obtained by arranging the nanoparticles in a linear array. Analytical formulas, describing such enhancement, are presented.
Originality/value
The results demonstrate the possibility to use the proposed device for medical diagnostics and optoelectronics applications.
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Bourahla Kheireddine, Belli Zoubida, Hacib Tarik and Achoui Imed
This study aims to focus on the application of the stochastic algorithms for optimal design of electrical machines. Among them, the authors are interested in particle swarm…
Abstract
Purpose
This study aims to focus on the application of the stochastic algorithms for optimal design of electrical machines. Among them, the authors are interested in particle swarm optimization and teaching–learning-based optimization.
Design/methodology/approach
The optimization process is realized by the coupling of the above methods to finite element analysis of the electromagnetic field.
Findings
To improve the performance of these algorithms and reduce their computation time, a coupling with the artificial neuron network has been realized.
Originality/value
The proposed strategy is applied to solve two optimization problems: Team workshop problem 25 and switched reluctance motor with flux barriers.
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Boquan Liu, Yicheng Zeng and Pinghua Tang
This paper aims to propose a noise-robust method to estimate the frequency of the reflective echo to reduce the negative effects of noise and improve the accuracy and resolution…
Abstract
Purpose
This paper aims to propose a noise-robust method to estimate the frequency of the reflective echo to reduce the negative effects of noise and improve the accuracy and resolution of a resonant surface acoustic wave (SAW) sensor.
Design/methodology/approach
The proposed approach exploits the singular value decomposition to obtain the frequency information of a SAW response signal and overcome the noise influences.
Findings
Compared with the commonly used Fourier transform (FT) method, the accuracy and resolution improvement of the proposed method used in the SAW sensor is validated.
Originality/value
The system using the proposed method delivers lesser standard deviation, that is, delivers higher performance than the conventional system using the fast FT method.
Mouna Zerzeri, Intissar Moussa and Adel Khedher
The purpose of this paper aims to design a robust wind turbine emulator (WTE) based on a three-phase induction motor (3PIM).
Abstract
Purpose
The purpose of this paper aims to design a robust wind turbine emulator (WTE) based on a three-phase induction motor (3PIM).
Design/methodology/approach
The 3PIM is driven by a soft voltage source inverter (VSI) controlled by a specific space vector modulation. By adjusting the appropriate vector sequence selection, the desired VSI output voltage allows a real wind turbine speed emulation in the laboratory, taking into account the wind profile, static and dynamic behaviors and parametric variations for theoretical and then experimental analysis. A Mexican hat profile and a sinusoidal profile are therefore used as the wind speed system input to highlight the electrical, mechanical and electromagnetic system response.
Findings
The simulation results, based on relative error data, show that the proposed reactive power control method effectively estimates the flux and the rotor time constant, thus ensuring an accurate trajectory tracking of the wind speed for the wind emulation application.
Originality/value
The proposed architecture achieves its results through the use of mathematical theory and WTE topology combine with an online adaptive estimator and Lyapunov stability adaptation control methods. These approaches are particularly relevant for low-cost or low-power alternative current (AC) motor drives in the field of renewable energy emulation. It has the advantage of eliminating the need for expensive and unreliable position transducers, thereby increasing the emulator drive life. A comparative analysis was also carried out to highlight the online adaptive estimator fast response time and accuracy.
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Xiuchen Wang, Yaping Li, Ying Su, Zhen Pan and Zhe Liu
The three-dimensional arrangement structure of the conductive fiber is an important factor of the shielding effectiveness of the electromagnetic shielding fabric (EMSF). However…
Abstract
Purpose
The three-dimensional arrangement structure of the conductive fiber is an important factor of the shielding effectiveness of the electromagnetic shielding fabric (EMSF). However, until now, the three-dimensional arrangement structure has not been described because of the complex structure, which leads to many difficulties for the subsequent analysis of the electromagnetic characteristics. Therefore, the purpose of this paper is to propose a feature extraction method to describe the arrangement structure of the conductive fiber based on the three-dimensional calibration and image processing technology, providing a new idea for the above problem.
Design/methodology/approach
First, the three-dimensional positions of the conductive fibers in the EMSF are calibrated using the VHX-600 3D digital microscope and the MATLAB7.5 software. The arrangement characteristics of the conductive fibers are analyzed, and equivalent twist, cross-sectional content, and average angle of a single fiber are proposed to describe the arrangement characteristic of the conductive fiber. Then, a digital description model of the conductive fiber is constructed according to the feature parameters and its three-dimensional structures are reproduced using CATIA. Finally, the reliability of the model is verified by an FDTD example, and the significance and application of the model are given.
Findings
The proposed method can provide the feature extraction and description for the complex spatial three-dimensional arrangement structure of conductive fibers. The feature parameters can reflect different micro arrangement features of the conductive fiber. The proposed idea and method can provide a solid foundation for subsequent studies of the electromagnetic properties of the EMSF.
Originality/value
The study in this paper is of great significance and academic value. This paper provides a new three-dimensional calibration method and constructs multiple feature parameters to describe the complex three-dimensional arrangement structure, providing a new effective method to overcome the problem of the conductive fiber description. The proposed method provides an important basis for the shielding mechanism, transmission characteristics, electromagnetic calculation and product design, and woven technology of the EMSF.
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Fatma Bakal, Ahmet Yapici, Muharrem Karaaslan and Oğuzhan Akgöl
The purpose of this paper is to investigate the effect of doping element on the microwave absorption performance of hexagonal nano boron nitride (h-nBN)-reinforced basalt fabric…
Abstract
Purpose
The purpose of this paper is to investigate the effect of doping element on the microwave absorption performance of hexagonal nano boron nitride (h-nBN)-reinforced basalt fabric (BF)/epoxy composites. A new type of hybrid composite that will be produced by the use of boron nitride as an additive that leads to increased radar absorption capability will be developed and a new material that can be used in aeronautical radar applications.
Design/methodology/approach
This study is focused on the microwave absorption properties of h-nBN doped basalt fabric-reinforced epoxy composites. Basalt fabric (BF)/epoxy composites (pure composites) and the BF/h-nBN (1 Wt.% h-nBN doped composites) hybrid composites were fabricated by vacuum infusion method. Phase identification of the composites were performed using X-ray diffraction (XRD), the 2θ scan range was from 10 to 60 with the scanning speed of 3°/min and surface morphologies of the composites were investigated using scanning electron microscopy (SEM). Microwave properties of samples were investigated through transmission/reflection measurements in Agilent brand 2-Port PNA-L Network Analyzer in the frequency range of 3–18 GHz. The prepared sample is positioned between two horn antennas with and without metal plate.
Findings
Experimental results show that h-nBN doped composite was synthesized successfully and the produced hexagonal nano boron nitride-added fiber laminated composite material has good absorption behavior when they are used with metallic sheets and good for isolation applications at many points in the 3–18 GHz band.
Originality/value
This paper will contribute to the literature on the use of basalt fabric, which are new types of fibers, and hexagonal nano boron nitride and the effects of boron nitride on radar absorption properties of composite material. It presents detail characterization of each composite by using XRD and scanning electron microscopy.
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Andrea G. Chiariello, Carlo Forestiere, Giovanni Miano and Antonio Maffucci
Nowadays, nano-antennas or nanoscale absorbers made by innovative materials such as carbon nanotubes are gaining more and more interest, because of their outstanding features. The…
Abstract
Purpose
Nowadays, nano-antennas or nanoscale absorbers made by innovative materials such as carbon nanotubes are gaining more and more interest, because of their outstanding features. The purpose of this paper is to investigate the scattering properties of carbon nanotubes, either isolated or arranged in arrays. The peculiar behaviour of such innovative materials is studied, taking also into account the finite length of the structure and the dependence of the scattering field from the operating temperature.
Design/methodology/approach
First a model is presented for the electrical transport along the carbon nanotubes, based on Boltzmann quasi-classical transport theory. The model includes quantistic and inertial phenomena observed in the carbon nanotube electrodynamics. The model also includes the effects of temperature. Using this electrodynamical model, the electromagnetic formulation of the scattering problem is cast in terms of a Pocklington-like equation. The numerical solution is obtained by means of the Galerkin method, with special care in handling the logarithmic singularity of the kernel. Case studies are carried out, either referred to isolated single-wall carbon nanotubes (SWCNTs) and array of SWCNTs.
Findings
The scattering properties of SWCNT are strongly influenced by the temperature and by the distance between the tubes. As temperature increases, the amplitude of the resonance peaks decreases, at a rate which is double the rate of changes of temperature. The resonance frequencies are insensitive to temperature. As for the distance between the tubes in an array, it influence the scattering resonance introducing a shift in the resonance frequencies which is appreciable for distances lower than the semi-length of the CNT. For higher distances the CNT scattered field may be regarded as the sum of the fields emitted by each CNT, as if they were isolated.
Research limitations/implications
As far as now only SWCNTs have been studied. The multi-wall carbon nanotubes would show a richer behaviour with temperature, due to the joint effect of reduction of the mean free path and increase of the number of conducting channels, as temperature increases.
Practical implications
Possible use of carbon nanotubes as absorbing material or scatterers.
Originality/value
The model presented here is based on a self-consistent and physically meaningful description of the CNT electrodynamics, which takes rigorously into account the effect of temperature, size and chirality of each CNT.
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Zoltán Pólik and Zoltán Kántor
– The purpose of this paper is to study the optimization of a pulsed-excitation gradiometric inductive sensing system.
Abstract
Purpose
The purpose of this paper is to study the optimization of a pulsed-excitation gradiometric inductive sensing system.
Design/methodology/approach
The authors applied numerical finite-element modeling for the simulation of the step responses of different target materials to identify the particular contribution of the magnetic permeability and the electric conductivity. Four materials of technical importance (aluminum, copper, constructional steel and stainless steel) and four fictive test materials were modeled for the comparison of different materials possessing a wide range of combinations of material parameters. A microcontroller-based measurement setup was implemented for the qualitative validation of the simulation results. A simple signal processing chain was also applied for the time-domain conversion of the direct step response signals to increase the time scale of the signals to be processed by common mixed-signal components.
Findings
The step response signals contain relevant information of the target material quality and the sensor-to-target distance. The target materials can be distinguished and the sensor-target distance can be determined by the evaluation of the step response signals with an appropriate algorithm based on the measurement of the time and voltage of an extreme of the time dependent measurement signals. Both direct and time-domain converted signals can be used for material independent proximity sensing.
Originality/value
In order to design an inductive proximity switch, an evaluation method of the response signals has been proposed by using an analog RLC circuit. With the presented method, a target material invariant inductive proximity switch can be realized.
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