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The ability to characterise highly conducting objects, that may also be highly magnetic, by the complex symmetric rank–2 magnetic polarizability tensor (MPT) is important for metal detection applications including discriminating between threat and non-threat objects in security screening, identifying unexploded anti-personnel landmines and ordnance and identifying metals of high commercial value in scrap sorting. Many everyday non-threat items have both a large electrical conductivity and a magnetic behaviour, which, for sufficiently weak fields and the frequencies of interest, can be modelled by a high relative magnetic permeability. This paper aims to discuss the aforementioned idea.

The numerical simulation of the MPT for everyday non-threat highly conducting magnetic objects over a broad range of frequencies is challenging due to the resulting thin skin depths. The authors address this by employing higher order edge finite element discretisations based on unstructured meshes of tetrahedral elements with the addition of thin layers of prismatic elements. Furthermore, computer aided design (CAD) geometrical models of the non-threat and threat object are often not available and, instead, the authors extract the geometrical features of an object from an imaging procedure.

The authors obtain accurate numerical MPT characterisations that are in close agreement with experimental measurements for realistic physical objects. The assessment of uncertainty shows the impact of geometrical and material parameter uncertainties on the computational results.

The authors present novel computations and measurements of MPT characterisations of realistic objects made of magnetic materials. A novel assessment of uncertainty in the numerical predictions of MPT characterisations for uncertain geometry and material parameters is included.

Recently there has been much discussion of the relevance to sociology of Wittgenstein's philosophy. In this discussion, reference has been made to Wittgenstein's remarks on classification. For instance, Dutton writes “After Wittgenstein, we might say that the category of acts which may be labelled criminal (or deviant) is the category: “any” acts”. (Ditton, 1979, p. 20). According to Hughes, “Wittgenstein uses the term “family resemblances” to make the point that states of affairs falling under a common term, such as ‘games’ show overlapping similarities and resemblances rather than universal, finitely specifiable common properties”. (1977, p. 72). However, the philosophical importance of Wittgenstein's remarks and their relevance to the concerns of the sociologist have not been fully explored. What precisely is Wittgenstein thought to be asserting and denying with his observations about games? After all, on the face of it, it hardly seems controversial or interesting to say that games resemble each other. It has been argued, most notably by Bambrough, that Wittgenstein's remarks are directed towards “the problem of universals”.

Appraises that the quality circle programme is one of the enablers of total quality management (TQM) projects. Points out that a considerable number of quality circles fail throughout the world in spite of their contributions toward attaining TQM objectives. Claims that lack of financial accountability causes management to underestimate the contributions of quality circles. Suggests a framework to financially account for quality circle programmes. Describes the efforts made to validate it by attempting implementation in a medium size manufacturing enterprise. Presents financial statements concerning a quality circle prepared using a commercially available accounting package. Concludes by discussing the future scope and issues connected with the implementation of the proposed quality circle accounting system.