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Article
Publication date: 1 June 2000

A. Savini

Gives introductory remarks about chapter 1 of this group of 31 papers, from ISEF 1999 Proceedings, in the methodologies for field analysis, in the electromagnetic community…

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Abstract

Gives introductory remarks about chapter 1 of this group of 31 papers, from ISEF 1999 Proceedings, in the methodologies for field analysis, in the electromagnetic community. Observes that computer package implementation theory contributes to clarification. Discusses the areas covered by some of the papers ‐ such as artificial intelligence using fuzzy logic. Includes applications such as permanent magnets and looks at eddy current problems. States the finite element method is currently the most popular method used for field computation. Closes by pointing out the amalgam of topics.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 19 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 5 March 2018

Hakim Sadou, Tarik Hacib, Hulusi Acikgoz, Yann Le-Bihan, Olivier Meyer and Mohamed Rachid Mekideche

The principle of microwave characterization of dielectric materials using open-ended coaxial line probe is to link the dielectric properties of the sample under test to the…

Abstract

Purpose

The principle of microwave characterization of dielectric materials using open-ended coaxial line probe is to link the dielectric properties of the sample under test to the measurements of the probe admittance (Y(f) = G(f)+ jB(f )). The purpose of this paper is to develop an alternative inversion tool able to predict the evolution of the complex permittivity (ε = ε′ – jε″) on a broad band frequency (f from 1 MHz to 1.8 GHz).

Design/methodology/approach

The inverse problem is solved using adaptive network based fuzzy inference system (ANFIS) which needs the creation of a database for its learning. Unfortunately, train ANFIS using f, G and B as inputs has given unsatisfying results. Therefore, an inputs selection procedure is used to select the three optimal inputs from new inputs, created mathematically from original ones, using the Jang method.

Findings

Inversion results of measurements give, after training, in real time the complex permittivity of solid and liquid samples with a very good accuracy which prove the applicability of ANFIS to solve inverse problems in microwave characterization.

Originality/value

The originality of this paper consists on the use of ANFIS with input selection procedure based on the Jang method to solve the inverse problem where the three optimal inputs are selected from 26 new inputs created mathematically from original ones (f, G and B).

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 August 2001

Zhengrong Tian and Charles Free

A review of the dielectric measurement techniques that are currently available for the characterization of thick film and LTCC materials at microwave and millimeter wave…

Abstract

A review of the dielectric measurement techniques that are currently available for the characterization of thick film and LTCC materials at microwave and millimeter wave frequencies is presented. The intention is to show the relative advantages and limitations of the various methods, and to provide some practical guide to the particular technique that is most suitable for a given type of material, for use in a particular application. In addition, a novel slit cavity resonator method is proposed to enable substrate parameters to be more easily measured, whilst retaining high measurement accuracy. Measured data on materials from a variety of manufacturers are presented to show the validity and usefulness of this method.

Details

Microelectronics International, vol. 18 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 13 July 2010

T. Hacib, H. Acikgoz, Y. Le Bihan, M.R. Mekideche, O. Meyer and L. Pichon

The dielectric properties of materials (complex permittivity) can be deduced from the admittance measured at the discontinuity plane of a coaxial open‐ended probe. This implies…

Abstract

Purpose

The dielectric properties of materials (complex permittivity) can be deduced from the admittance measured at the discontinuity plane of a coaxial open‐ended probe. This implies the implementation of an inversion procedure. The purpose of this paper is to develop a new non‐iterative inversion methodology in the field of microwave characterization allowing reducing the computation cost comparatively to iterative procedures.

Design/methodology/approach

The inversion methodology combines the support vector machine (SVM) technique and the finite element method (FEM). The SVM are used as inverse models. They show good approximation and generalization capabilities. FEM allows the generation of the data sets required by the SVM parameter adjustment. A data set is constituted of input (complex admittance and frequency) and output (complex permittivity) pairs.

Findings

The results show the applicability of SVM to solve microwave inverse problems instead of using traditional iterative inversion methods which can be very time‐consuming. The experimental results demonstrate the accuracy which can be provided by the SVM technique.

Practical implications

The paper allows extending the capability of microwave characterization cells developed at Laboratoire de Génie Électrique de Paris.

Originality/value

A new inversion method is developed and applied to microwave characterization. This new concept introduces SVM in the context of microwave characterization. SVM results and iterative inversion procedure results are compared in order to evaluate the effectiveness of the developed technique.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 10 May 2019

Krzysztof Kubiczek and Marian Kampik

The purpose of this study is to develop and investigate a fast and accurate algorithm for the modeling of characteristic impedance of double-layer coaxial waveguides.

Abstract

Purpose

The purpose of this study is to develop and investigate a fast and accurate algorithm for the modeling of characteristic impedance of double-layer coaxial waveguides.

Design/methodology/approach

This paper presents the newly developed numerically stable analytical formula for calculation of the characteristic impedance of double-layer coaxial conductor and its elements such as resistance, inductance, capacitance and conductance per unit length. The formula contains modified scaled Bessel functions. The results of the developed analytical formula were compared with results obtained from the axis-symmetric 2D and 3D finite element method (FEM) simulations, using three different solvers.

Findings

The proposed method shows a good agreement between results obtained with the new fast and stable analytical model and particular FEM models, selected depending on frequency range. The relative difference between characteristic impedance calculated using the new analytical method and obtained from chosen FEM method for discussed frequency range is less than 0.1 per cent which proves the correctness of the new analytical formula. Noteworthy is the fact that the relative difference of the resistance computed using the developed analytical method and obtained with Maxwell FEM solver for the frequency in range from 1 Hz to 10 MHz is less than 0.01 per cent. The presented work shows that when the calculations are performed over wide frequency range, it is necessary to use more than one solver, especially when the wavelength is comparable with dimensions of the conductor. The computation time of the new analytical model is much shorter than the computation time of FEM.

Originality/value

An efficient, numerically stable algorithm for computation of characteristic impedance of a double-layer coaxial conductor (waveguide).

Article
Publication date: 16 April 2020

Jayshri Sharad Kulkarni

The purpose of this manuscript is to present a novel, compact and ultra-thin “3”-shaped monopole antenna for wireless operations in the laptop computer. The thickness of the…

Abstract

Purpose

The purpose of this manuscript is to present a novel, compact and ultra-thin “3”-shaped monopole antenna for wireless operations in the laptop computer. The thickness of the antenna is only 0.2 mm and is designed using only a pure copper strip of size 17.5 × 6 mm2.

Design/methodology/approach

The simple structure of the proposed antenna consists of two monopole radiating strips, namely, AC and CD and an open-ended rectangular tuning stub BE of length 9mm.

Findings

This structure inspires two resonating modes at 3.45 and 5.5 GHz and achieves the measured impedance band width as 20% (3.21-3.91) GHz in lower band (F_l) and 15% (5.05-5.85) GHz in the upper band (F_u) for voltage standing wave ratio < 2. These two bands cover 5GHz wireless local area network (WLAN) and 3.3-3.6GHz (sub 6GHz) 5G bands. The measured radiation performance including, nearly omnidirectional radiation patterns, a stable gain of around 5 dBi and excellent efficiency around 90% in both operating bands have been achieved. Furthermore, a simplified equivalent circuit model has been derived and its simulation is performed. The simulated and measured results are in good agreement, which demonstrates the applicability of the antenna structure for WiMAX/WLAN operations in the prominent ultra-thin laptop computers.

Originality/value

The proposed antenna is designed without using any reactive elements, vias or matching circuits for excitation of WLAN and 5G bands in the laptop computers. The design also does not require any additional ground for mounting the antenna. The proposed antenna has a very low profile, is ultra-thin, cost-effective, easy to manufacture and can be easily embedded inside next generation laptop computers.

Details

Circuit World, vol. 46 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 February 1988

Larry L. Learn

This article provides a broad overview of telecommunications and network‐related technologies. Topics covered include identification and review of network elements, analog and…

214

Abstract

This article provides a broad overview of telecommunications and network‐related technologies. Topics covered include identification and review of network elements, analog and digital signals, synchronous and asynchronous transmission formats, transmission media and equipment, transmission techniques and characteristics, multiplexing, network types, access technologies, network architectures and topologies, local‐area network technologies and attributes, protocols and protocol issues, gateways, internetworking, local networking alternatives, equipment certification, and various aspects of network management. It is intended to provide the practicing professional in the field of library and information science with a broad, up‐to‐date technical review that might serve to support and facilitate further investigation of current developments in networks and networking. Although the broad range of topics is not treated in depth, numerous references are provided for further investigation.

Details

Library Hi Tech, vol. 6 no. 2
Type: Research Article
ISSN: 0737-8831

Article
Publication date: 1 March 1945

In a spinner for the hub of an airscrew, a spinner shell, spoked supports therefor adapted for attachment to said hub, an annular member adapted for detachable connexion with said…

Abstract

In a spinner for the hub of an airscrew, a spinner shell, spoked supports therefor adapted for attachment to said hub, an annular member adapted for detachable connexion with said spinner shell, a plurality of brackets fixed around said member, pivot pins carried by said brackets with their axes arranged tangential to a circle concentric with the rotational axis of said spinner shell, open‐ended sockets at the ends of the spokes of said supports adapted for engagement with said pins and rubber bushes arranged between said pins and sockets with their ends bearing against said brackets.

Details

Aircraft Engineering and Aerospace Technology, vol. 17 no. 3
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 April 2006

Mary Welch

The purpose of this paper is to respond to a call for academia to partner industry by offering new thinking on public relations research and practice.

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Abstract

Purpose

The purpose of this paper is to respond to a call for academia to partner industry by offering new thinking on public relations research and practice.

Design/methodology/approach

The paper rethinks relationship management by broadening previous views on the dimensions of relationships. Distrust is proposed as a 12th dimension, adding to Ledingham's 11. It suggests that trust and distrust exist simultaneously within business‐to‐business relationships and that trust and distrust are employed in a coaxial view of relationships within a zone of approval. The paper draws on the work of relationship management theorists and those who identify trust as a key component of relationships. Conceptual considerations are coupled with empirical data collected in a qualitative case study of relationships between the communications team of a blue chip UK utilities company and service provider (SP) organisations.

Findings

Analysis supports the broader understanding of trust and distrust operating simultaneously in a zone of approval and may help managers to analyse their business‐to‐business relationships.

Research limitations/implications

Findings of qualitative research case studies are not themselves generalisable. This paper uses those findings to develop relationship management theory which may be of interest to practitioners. The findings are also used to generate ideas for further research.

Practical implications

An embryonic model is suggested that may provide managers with a tool to use when considering the elements of trust and distrust in relationship management.

Originality/value

Contributes to a broader understanding of relationships by suggesting distrust as a 12th dimension in the coaxial view of relationships. Proposes a zone of approval model to enable the exploration of trust and distrust in relationship management.

Details

Journal of Communication Management, vol. 10 no. 2
Type: Research Article
ISSN: 1363-254X

Keywords

Article
Publication date: 1 January 1957

An axial‐flow blower for delivering cooling air in large volume, comprising a generally cylindrical rotor and a fixed coaxial housing spaced thereabout, open at its front end for…

Abstract

An axial‐flow blower for delivering cooling air in large volume, comprising a generally cylindrical rotor and a fixed coaxial housing spaced thereabout, open at its front end for intake of air and at its rear end for discharge of air, a generally cylindrical fixed shell located within the housing as a smooth rearward continuation of said rotor, a series of angularly distributed diffuser blades connecting the housing and the interior shell and supporting the latter, journal means for the rotor carried by said shell, a coaxial annular shroud located intermediate the rotor and the housing and terminating at its rear end immediately in advance of the outer ends of said diffuser blades, a series of blower blades distributed about the space between the rotor and the shroud, and mounted upon the rotor terminating immediately in advance of the diffuser blades, a series of turbine blades distributed about the rear edge of said shroud, intermediate the shroud and the housing and immediately ahead of the diffuser blades, an annular high compression air duct formed in the housing and having an inlet for connection to a source of highly compressed air, and a series of angularly spaced rearwardly directed nozzles formed in said housing and located forwardly of said turbine blades, for discharge of air from said air duct rear‐wardly against the turbine blades and then immediately past said diffuser blades, to mingle with air discharged rearwardly through the diffuser blades from the blower blades.

Details

Aircraft Engineering and Aerospace Technology, vol. 29 no. 1
Type: Research Article
ISSN: 0002-2667

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