BCI meeting 2005--workshop on technology: hardware and software.

This paper describes the outcome of discussions held during the Third International BCI Meeting at a workshop to review and evaluate the current state of BCI-related hardware and software. Technical requirements and current technologies, standardization procedures and future trends are covered. The main conclusion was recognition of the need to focus technical requirements on the users' needs and the need for consistent standards in BCI research.     

Subcomplete generalizations of graph isomorphism

We present eight group-theoretic problems in NP one of which is a reformulation of graph isomorphism. We give technical evidence that none of the problems is NP-complete, and give polynomial time reductions among the problems. There is a good possibility that seven of these problems are harder than graph isomorphism (relative to polynomial time reduction), so that they might be examples of natural problems of intermediate difficulty, situated properly between the class of NP-complete problems and the class P of problems decidable in deterministic polynomial time. Because of strong structural similarity, two of the apparently harder problems can be interpreted as generalized isomorphism and generalized automorphism, respectively. Whether these problems ultimately prove to be harder than graph isomorphism seems to depend, in part, on the open problem whether every permutation group of degree n arises as the automorphism group of a combinatorial structure of size polynomial in n. Finally, we give an O(n² · k) algorithm for constructing the centralizer of a permutation group of degree n presented by a generating set of k permutations. Note that we may assume that k is O(n · log n), without loss of generality. This problem is a special case of one of the harder group-theoretic problems. From the method of constructing the centralizer, we recover results about the group-theoretic structure of the centralizer. Furthermore, applying our algorithm for intersecting with a normalizing permutation group, we show how to find the center of a permutation group of degree n in O(n⁶) steps, having constructed the centralizer of the group first.     

Beitrag zur rechnerischen Ermittlung der Temperaturverteilung in Warmwalzen

Rechnerische Ansätze zum Ermitteln der Temperaturverteilung im Walzeninnern. Walzenoberflächentemperatur im Walzspalt und außerhalb des Walzspaltes. Berechnungsbeispiel.     

A simple approximation to the current on the surface of an isolated thin cylindrical center-fed dipole antenna of arbitrary length

The use of a simple trigonometric series to approximate the current distribution on isolated center-fed dipole antennas has been found to give accurate results. Unilike iterative and numerical solutions, the functional form of the approximate distribution permits the simple computation of the axial electric fields and radiating properties of the dipole.     

Evaluation of seeing-induced cross talk in tip-tilt-corrected solar polarimetry

We reanalyze the effects of atmosphere-induced image motions on the measurement of solar polarized light using a formalism developed by Lites. Our reanalysis is prompted by the advent of adaptive optics (AO) systems that reduce image motion and higher-order aberrations, by the availability of liquid crystals as modulation devices, and by the need to understand how best to design polarimeters for future telescopes such as the Advanced Technology Solar Telescope. In this first attempt to understand the major issues, we analyze the influence of residual image motion (tip-tilt) corrections of operational AO systems on the cross talk between Stokes parameters and present results for several polarization analysis schemes. Higher-order wave-front corrections are left for future research. We also restrict our discussion to the solar photosphere, which limits several important parameters of interest, using some recent magnetoconvection simulations.