Phase-accuracy comparisons and improved far-field estimates for 3-D edge elements on tetrahedral meshes

Edge-element methods have proved very effective for 3-D electromagnetic computations and are widely used on unstructured meshes. However, the accuracy of standard edge elements can be criticised because of their low order. This paper analyses discrete dispersion relations together with numerical propagation accuracy to determine the effect of tetrahedral shape on the phase accuracy of standard 3-D edgeelement approximations in comparison to other methods. Scattering computations for the sphere obtained with edge elements are compared with results obtained with vertex elements, and a new formulation of the far-field integral approximations for use with edge elements is shown to give improved cross sections over conventional formulations.

A connection too far

Examines the test for vicarious liability for intentional torts laid down by the House of Lords in Lister v Hesley Hall Ltd requiring a close connection between an employee's tort and his employment. Reviews subsequent case law, highlighting inconsistencies in the courts' approach as to whether a close connection existed. Asks whether the cases suggest that the courts are applying a separate test based on the fairness of holding the employer liable. [From Legal Journals Index]