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Article
Publication date: 1 October 1998

Gerhard Paoli and Oszkár Bíró

One way to deal with non‐linearity in the case of time harmonic excitation of the electric and magnetic fields in ferromagnetic media is to introduce an effective material to…

570

Abstract

One way to deal with non‐linearity in the case of time harmonic excitation of the electric and magnetic fields in ferromagnetic media is to introduce an effective material to model the ferromagnetic region. This fictitious material is constant throughout a period but inhomogeneous and it takes into account the non‐linear relationship between the field quantities. Several methods to create an effective magnetization curve are presented and different finite element formulations are applied to these. Some of these methods are known from the literature for 1D and 2D problems but not for 3D ones and they have only be used for a magnetic vector potential formulation so far. In the present paper they are extended for general vector and scalar potential formulations. Further possible ways to introduce such an effective material to take into account saturation effects are shown. All these different methods are investigated on a non‐linear 3D time harmonic eddy current problem using complex formalism.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 17 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 10 July 2009

Karl Hollaus, Oszkár Bíró, Gernot Matzenauer, Christian Stockreiter, Bernhard Weiß, Peter Caldera and Gerhard Paoli

The purpose of this paper is to study the extraction of scattering parameters (SPs) from simple structures on a printed circuit board (PCB) by the finite difference time domain…

274

Abstract

Purpose

The purpose of this paper is to study the extraction of scattering parameters (SPs) from simple structures on a printed circuit board (PCB) by the finite difference time domain (FDTD) method with the aid of a surface impedance boundary condition (SIBC).

Design/methodology/approach

The incorporation of SIBC into the FDTD method is described for the general case. The excitation of a field problem by a field pattern and the transition from the field solution to a circuit representation by SPs is discussed.

Findings

SPs obtained by FDTD with SIBC are validated with semi‐analytic solutions and compared with results obtained by different numerical methods. Results of a microstrip with a discontinuity considering losses are presented demonstrating the capability of the present method.

Originality/value

The comparison of numerical results obtained by different methods demonstrates the capability of the present method to extract SPs from PCBs very efficiently.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 February 1942

A measuring and indicating instrument comprising means responsive to changes in the magnitude of the quantity being measured, indicating means comprising a disc having a radial…

19

Abstract

A measuring and indicating instrument comprising means responsive to changes in the magnitude of the quantity being measured, indicating means comprising a disc having a radial slot therein, a screw‐threaded guide having a shaft coaxial with said disc, a helix mounted upon said shaft adjacent said disc, and means connecting said change responsive means to said shaft for actuating said helix to move it through the radial slot in said disc to form an indicating area which increases or decreases in size in proportion to an increase or decrease of the quantity being measured.

Details

Aircraft Engineering and Aerospace Technology, vol. 14 no. 2
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 17 March 2020

Paschalis Charalampous, Ioannis Kostavelis and Dimitrios Tzovaras

In recent years, additive manufacturing (AM) technology has been acknowledged as an efficient method for producing geometrical complex objects with a wide range of applications…

2004

Abstract

Purpose

In recent years, additive manufacturing (AM) technology has been acknowledged as an efficient method for producing geometrical complex objects with a wide range of applications. However, dimensional inaccuracies and presence of defects hinder the broad adaption of AM procedures. These factors arouse concerns regarding the quality of the products produced with AM and the utilization of quality control (QC) techniques constitutes a must to further support this emerging technology. This paper aims to assist researchers to obtain a clear sight of what are the trends and what has been inspected so far concerning non-destructive testing (NDT) QC methods in AM.

Design/methodology/approach

In this paper, a survey on research advances on non-destructive QC procedures used in AM technology has been conducted. The paper is organized as follows: Section 2 discusses the existing NDT methods applied for the examination of the feedstock material, i.e. incoming quality control (IQC). Section 3 outlines the inspection methods for in situ QC, while Section 4 presents the methods of NDT applied after the manufacturing process i.e. outgoing QC methods. In Section 5, statistical QC methods used in AM technologies are documented. Future trends and challenges are included in Section 6 and conclusions are drawn in Section 7.

Findings

The primary scope of the study is to present the available and reliable NDT methods applied in every AM technology and all stages of the process. Most of the developed techniques so far are concentrated mainly in the inspection of the manufactured part during and post the AM process, compared to prior to the procedure. Moreover, material extrusion, direct energy deposition and powder bed processes are the focal points of the research in NDT methods applied in AM.

Originality/value

This literature review paper is the first to collect the latest and the most compatible techniques to evaluate the quality of parts produced by the main AM processes prior, during and after the manufacturing procedure.

Details

Rapid Prototyping Journal, vol. 26 no. 4
Type: Research Article
ISSN: 1355-2546

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