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The Hugub open-air site in Ethiopia well-dated to between 600 and 500 ka yields the earliest securely dated and found in situ Late Acheulean archaeology in Africa. The studied lithic assemblage includes numerous, often diminutive broad-tipped ovate and pointed bifaces, many of which are made on large flakes. These show the earliest evidence of intensive on-site resharpening thru modification and edge rejuvenation as well as the earliest use of the plano-convex method of biface manufacture. This emergent pattern of biface production, maintenance, and discard is typical for the Late Acheulean related to post-erectus Homo, referred to as Homo heidelbergensis (for European forms) or Homo rhodesiensis (for African forms), as well as post-Acheulean industries, and has no analogs among earlier Acheulean populations of Homo erectus.

Field-oriented methods which describe the physical properties of microwave circuits and optical structures are an indispensable tool to avoid costly and time-consuming redesign cycles. Commonly the electromagnetic characteristics of the structures are described by the scattering matrix which is extracted from the orthogonal decomposition of the electric field. The electric field is the solution of an eigenvalue and a boundary value problem for Maxwell’s equations in the frequency domain. We discretize the equations with staggered orthogonal grids using the Finite Integration Technique (FIT). Maxwellian grid equations are formulated for staggered nonequidistant rectangular grids and for tetrahedral nets with corresponding dual Voronoi cells. The interesting modes of smallest attenuation are found solving a sequence of eigenvalue problems of modified matrices. To reduce the execution time for high-dimensional problems a coarse and a fine grid is used. The calculations are carried out, using two levels of parallelization. The discretized boundary value problem, a large-scale system of linear algebraic equations with different right-hand sides, is solved by a block Krylov subspace method with various preconditioning techniques. Special attention is paid to the Perfectly Matched Layer boundary condition (PML) which causes non physical modes and a significantly increased number of iterations in the iterative methods.