Search results

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.

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.

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.

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.

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

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

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

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

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

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.

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.

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.

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.

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

Die Redeweise von der «touristischen Explosion» in der jüngsten Gegenwart gehört ins «Wörterbuch des Unmenschen». Sie kennzeichnet aber drastisch einen Vorgang, dem eine Sprengwirkung nicht ganz abgesprochen werden kann. Jahrtausendalte Gewohnheiten der Sesshaftigkeit wurden seit rund 20 Jahren durch den Tourismus in einem früher unvorstellbaren Ausmass aufgebrochen. Die Erschütterung erfasste auch die Jugend. Das Beben pflanzt sich fort, zeitlich und räumlich, nicht etwa sich verebbend wie bei einem einzigen Erdstoss. Einmal in Schwung gesetzt, wurde der Tourismus allgemein, somit auch jener der Jugend, zu einem perpetuum mobile.

Nach den vorliegenden österreichischen Erfalirungen kann der Fremdenverkehr ein wertvolles Element der regionalen Wirtschaftsentwicklung sein. Dabei ist es gleichgültig, ob ausländisches oderinländisches Gästepublikum gewonnen wird.

The purpose of this paper is to reconstruct the marketing history of medical marijuana cigarettes in the past three decades of Austria-Hungary.

This paper constructs an analytical narrative based on information scattered in historical periodicals.

Towards the end of Habsburg rule, two Ljubljana-based pharmacists, the Trnkóczy brothers, managed to establish themselves as monopolistic suppliers of pre-rolled medical marijuana cigarettes for the entire Austrian part of the dual monarchy. Garnering the support of the regional Carniolan Government, Julius von Trnkóczy successfully argued his wares were not affected by the prohibition passed against imported French medicinal cigarettes. This happened despite medical opposition, suggesting that Trnkóczys could only operate this business because of their elevated social status. In the past decade of the 19th century, Ubald von Trnkóczy took advantage of newly loosened regulation to obtain an official permit by the royal-imperial government in Vienna. This was followed, in late 1909, by an advertising campaign covering mass media throughout the empire. This was enabled, amongst others, by a cutting down on medicinal claims. Their declining price is further indication that the cigarettes were mass marketed, especially as their core ingredient, cannabis, underwent price inflation.

Because of its later illegality, the research subject was for a long time considered embarrassing, leading to an absence of retrievable documents. Missing archival sources are thus a major limitation, but one which can be overcome by the concurrent reading of historical periodicals – ranging from mass-market newspapers to specialist journals and legal texts. This paper has implications for 21st-century challenges in the marketing of newly legalized medical marijuana.

This paper discusses the marketing history of cannabis, a drug rarely discussed in historical literature outside its medical and regulatory context, and reconstructs previously forgotten case histories.