Efficient calculation of transient fields in multilayered media
A scheme for computing fields radiated by transient sources residing above a grounded multilayered medium is proposed. First, the causality trick is invoked to obtain a new representation of the field excited by transient sources. Second, starting from this representation, a novel approach to rapidly computing this field assuming that the mutilayered stack is electrically thin, is developed. Third, the approach is applied to the accelerated calculation of multilayered transient fields.
Time-Domain Integral Equation Solver for Planar Circuits Over Layered Media Using Finite Difference Generated Green's Functions
A simple, highly accurate, and efficient 2D finite-difference technique for computing the direct convolution of time-domain Green's functions (TDGFs) of layered media with temporal interpolators is presented. The proposed TDGFs are incorporated into a recently developed marching-on-in-time (MOT)-based time-domain integral equation (TDIE) solver based on noncausal high-order B-Spline temporal interpolators without requiring the prediction of future unknowns. Numerical results demonstrating the applicability of the technique to the analysis of various microwave structures are presented.
New records of Grania (Clitellata, Enchytraeidae) in the Northeast Atlantic (from Tromsø to the Canary Islands), with descriptions of seven new species
Previous northeast Atlantic records of Grania have been mainly from Germany, southern Scandinavia, and the Atlantic shores of France, Spain and Ireland. They were referred to eight species, with one, G. atlantica, reported from the continental slope. We have examined various unpublished collections from sources spanning from the Canary Islands to the Norwegian Arctic. Apart from new information on morphology, taxonomy, and distribution of known species, we describe seven new taxa (G. canaria, G. fortunata, G. mauretanica, G. aquitana, G. vikinga, G. torosa, and G. papillinasus). The collection of G. papillinasus from 2630-2885 m represents a new depth record for Enchytraeidae. Twenty-five of the now 57 Grania species occur in the North Atlantic. The North Atlantic drift moderates sea temperatures along the northeast Atlantic coasts, probably facilitating the wide latitudinal range of some taxa, as well as actual dispersal within the region. A "chaetal index" (chaetal length : chaetal foot length) is proposed to differentiate L-shaped chaetae at the species level. Complex relationships within the "type 6 group" of Grania suggest that groupings established using certain combinations of penial, chaetal and spermathecal patterns may not be monophyletic. For a better phylogenetic resolution, additional morphological details of these and other characters are needed.