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Article
Publication date: 25 July 2019

Christopher Stroehlein, Hermann Landes, Andreas Krug and Peter Dietz

The purpose of this paper is to investigate magneto-mechanical coupling occurring in magnetic resonance imaging (MRI) systems. The authors study influence of the strength…

Abstract

Purpose

The purpose of this paper is to investigate magneto-mechanical coupling occurring in magnetic resonance imaging (MRI) systems. The authors study influence of the strength of the background field on the coupling of mechanically isolated, conductive cylindrical structures and the so-called shields. This coupling has a strong impact on frequency-dependent thermal losses occurring in the shield structures which are of high importance in MRI systems.

Design/methodology/approach

In the investigations, numerical methods are applied. First, finite element methods taking into account the full magneto-mechanical coupling are used to investigate the coupled physical phenomena. As these calculations may be time-consuming, several approximate predictive methods are derived. Modal expansion factors and participation factors are based on combinations of structural eigenmode calculations and eddy current calculations using Biot–Savart representations of the dynamic gradient field. In addition, a parallelism factor expressed in terms of the shield vibrations is defined to measure the coupling between the distinct cylinders.

Findings

It is found that the strength of the background field strongly influences the coupling of the distinct shields, which strongly increases the parallelism of the shield vibrations. Furthermore, modal expansion and participation factors are significantly influenced, caused by frequency shifts due to magnetic stiffening and increased magnetic coupling.

Research limitations/implications

The current work is limited to the modal expansions of a single shield. This needs to be extended in the future as comparison of modal expansion factors and finite element simulation indicate.

Originality/value

The defined factors estimating parallelism and modal participation in magneto-mechanical coupling are original work and studied for the first time.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 38 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 19 June 2007

Michael Ertl and Hermann Landes

This paper aims to present a 3D numerical analysis of the load noise generation associated with large, oil immersed three‐phase power transformers.

Abstract

Purpose

This paper aims to present a 3D numerical analysis of the load noise generation associated with large, oil immersed three‐phase power transformers.

Design/methodology/approach

After studying the mechanical behavior of the winding structures of transformers, the results of coupled magneto‐mechanical simulations are presented.

Findings

An appropriate modeling strategy of the vibratory winding structures of transformers is necessary to reduce complexity and computational resources.

Originality/value

The presented model setup describes a fully transient, 3D coupled magneto‐mechanical simulation of the vibratory winding structure of large power transformers.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 1 March 1985

Tomas Riha

Nobody concerned with political economy can neglect the history of economic doctrines. Structural changes in the economy and society influence economic thinking and…

Abstract

Nobody concerned with political economy can neglect the history of economic doctrines. Structural changes in the economy and society influence economic thinking and, conversely, innovative thought structures and attitudes have almost always forced economic institutions and modes of behaviour to adjust. We learn from the history of economic doctrines how a particular theory emerged and whether, and in which environment, it could take root. We can see how a school evolves out of a common methodological perception and similar techniques of analysis, and how it has to establish itself. The interaction between unresolved problems on the one hand, and the search for better solutions or explanations on the other, leads to a change in paradigma and to the formation of new lines of reasoning. As long as the real world is subject to progress and change scientific search for explanation must out of necessity continue.

Details

International Journal of Social Economics, vol. 12 no. 3/4/5
Type: Research Article
ISSN: 0306-8293

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Article
Publication date: 1 February 1956

Serious contributions to library history are all too rare, and the series of studies now being issued from the University of South Africa Department of Librarianship under…

Abstract

Serious contributions to library history are all too rare, and the series of studies now being issued from the University of South Africa Department of Librarianship under the collective title of Mousaion is to be welcomed. It is proposed to publish six numbers of this journal annually in English, French, German, Italian, or Spanish. The first number dealt with Les Bibliothèques Ptoléméennes d'Alexandrie, and this is followed by two volumes comprising (in the author's words) a ‘methodological prolegomena to library history’. The term ‘encyclopaedia’ in the title is used in the sense of a technical discipline of historical librarianship. The project is formidable, and it is attacked with meticulous and laborious thoroughness: so laborious indeed that one sometimes has the impression of an elephant cracking a hazel nut. In history, over‐complication is as misleading as over‐simplification, and the scientific historian occasionally seems to introduce his own complexities into a problem for the sheer pleasure of disentangling them. Professor de Vleeschauwer is right in saying that in this field of library history the time for anecdotes has gone (though properly employed the anecdote has its uses). He is equally right in condemning the amateurishness of much that has passed for library history, and the ‘lyricism’ (as he calls it) of works such as Parsons's The Alexandrian Library. But is he right in supposing that the only alternative is to bring into action the whole armament of deductive logic and scientific method, in his anxiety to make his picture philosophically complete, with no term undefined and no particle of it unclassified or unorganized? His guns are too heavy for his target.

Details

Journal of Documentation, vol. 12 no. 2
Type: Research Article
ISSN: 0022-0418

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Book part
Publication date: 24 June 2014

Mark S. Mizruchi and Mikell Hyman

We argue that the United States has experienced a decline of economic, political, and military power since the 1970s, and that this decline can be attributed in part to…

Abstract

We argue that the United States has experienced a decline of economic, political, and military power since the 1970s, and that this decline can be attributed in part to the fragmentation of the American corporate elite. In the mid-twentieth century, this elite – constrained by a highly legitimate state, a relatively powerful labor movement, and an active financial community – adopted a moderate and pragmatic strategy for dealing with the political issues of the day. The “enlightened self-interest” of corporate leaders contributed to a strong economy with a relatively low level of inequality and an expanding middle class. This arrangement broke down in the 1970s, however, as increasing foreign competition and two energy crises led to spiraling inflation and lower profits. In response, the corporate elite waged an aggressive (and ultimately successful) assault on government regulation and organized labor. This success had the paradoxical effect of undermining the elite’s own sources of cohesion, however. Having won the war against government and labor, the group no longer needed to be organized. The marginalization of the commercial banks and the acquisition wave of the 1980s exacerbated the fragmentation of the corporate elite. No longer able to act collectively by the 1990s, the corporate elite was now incapable of addressing issues of business and societal-wide concern. Although increasingly able to gain individual favors from the state, the elite’s collective weakness has contributed to the political gridlock and social decay that plague American society in the twenty-first century.

Details

The United States in Decline
Type: Book
ISBN: 978-1-78350-829-7

Keywords

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Article
Publication date: 1 February 1964

Walter Hunziker

Angesichts der Kostensteigerung und des Personalmangels hat die Rationalisierung auch im Gastgewerbe — als Oherhegriff von Hotellerie und Gastwirtschafts‐ oder…

Abstract

Angesichts der Kostensteigerung und des Personalmangels hat die Rationalisierung auch im Gastgewerbe — als Oherhegriff von Hotellerie und Gastwirtschafts‐ oder Gaststättengewerbe zu verstehen — ständig» an Bedeutung und Dringlichkeit zugenommen. Sie stellt dabei um so heiklere, freilich zugleich interessantere Probleme, als ihre Verwirklichung hier ganz besondere Schwierigkeiten bereitet und sich weit dornenvoller gestaltet als etwa in der Industrie.

Details

The Tourist Review, vol. 19 no. 2
Type: Research Article
ISSN: 0251-3102

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Book part
Publication date: 10 December 2018

Bart Kamp

This study explores whether machinery firms with a ‘hidden champions’ profile leverage Industry 4.0 practices to roll out smart services; whether this allows them to get a…

Abstract

This study explores whether machinery firms with a ‘hidden champions’ profile leverage Industry 4.0 practices to roll out smart services; whether this allows them to get a firm grip on their installed base; and whether it allows them to expand their international (service) business. The research is conducted based on exploratory, multiple-case study methods.

The author finds that the implementation of smart services can improve a machine tool builder’s hold on its installed base and expand the scope of its international (service) business. However, the study also finds that the ability to capitalise on this potential depends on a series of moderating variables. The study also concludes that there is a risk that smart services do not unlock a strong willingness-to-pay among potential customers.

It, therefore, calls into question several conventional wisdoms, such as the possibilities that Industry 4.0 offers for suppliers operating in business-to-business markets, and the receptiveness to smart services by buyers in such markets. Finally, it highlights the specific liabilities faced by hidden champions with regard to expanding their smart services business.

The chapter provides practical insights into the hurdles that industrial suppliers must overcome in their attempts to achieve uptake of smart services by customers, particularly within a cross-border context.

Details

International Business in the Information and Digital Age
Type: Book
ISBN: 978-1-78756-326-1

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Article
Publication date: 1 January 1987

T.K. Hellen and W.S. Blackburn

A review is made of methods for calculating parameters characterizing crack tip behaviour in non‐linear materials. Convenient methods of calculating J‐integral type…

Abstract

A review is made of methods for calculating parameters characterizing crack tip behaviour in non‐linear materials. Convenient methods of calculating J‐integral type quantities are reviewed, classified broadly into two groups, as domain integrals and virtual crack extension techniques. In addition to considerations of how such quantities may be calculated by finite elements, assessment methods of conducting the actual incremental analyses are described.

Details

Engineering Computations, vol. 4 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 March 1987

Klaus M.F. Edelmann

Einführung Im weltwirtschaftlichen, wie auch welttouristischen Rahmen gesehen, ist Lateinamerika ein Hoffnungsund Zukunftsland für die gesamte Weltbevölkerung und den…

Abstract

Einführung Im weltwirtschaftlichen, wie auch welttouristischen Rahmen gesehen, ist Lateinamerika ein Hoffnungsund Zukunftsland für die gesamte Weltbevölkerung und den Welttourismus.

Details

The Tourist Review, vol. 42 no. 3
Type: Research Article
ISSN: 0251-3102

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Book part
Publication date: 17 December 2015

Abstract

Details

Knowing, Becoming, doing as Teacher Educators: Identity, Intimate Scholarship, Inquiry
Type: Book
ISBN: 978-1-78441-140-4

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