Parameterized Two-Player Nash Equilibrium

We study the problem of computing Nash equilibria in a two-player normal form (bimatrix) game from the perspective of parameterized complexity. Recent results proved hardness for a number of variants, when parameterized by the support size. We complement those results, by identifying three cases in which the problem becomes fixed-parameter tractable. Our results are based on a graph-theoretic representation of a bimatrix game, and on applying graph-theoretic tools on this representation.     

The modification effect of different compounds for protection of magnesium against corrosion

A protective layers were prepared on a magnesium electrode by treatment in different solutions and times after modification in 0.15 M HCl for 20 seconds. The corrosion of magnesium coated protective layer with different compounds was studied by using potential-time, current-potential curves and AC impedance spectra. The coatings morphology depends on the treating bath compositions and immersion times. The protective efficiencies of the surface layers were calculated by using corrosion rates obtained by extrapolation of Tafel zones of current-potential curves to the corrosion potential and by using Stern-Geary equation with polarization resistance from impedance spectra.     

Structure,homogeneity ranges,magnetic, and electrical properties of the ordered Laves phases RENi4Mg with MgCu4Sn type structure

New ordered Laves phases RENi₄Mg (RE = Sc, Sm, Tb–Lu) were synthesized from the elements in sealed tantalum ampoules in an induction furnace. Six of the structures were refined on the basis of X-ray single crystal data. The diffraction experiments gave hint for small homogeneity ranges RE_1+xNi₄Mg_1?x. Magnetic susceptibility measurements show Curie–Weiss behavior for RE = Gd, Dy, Ho, Tm, Yb and the resulting effective magnetic moments suggest both stable trivalent states for all RE and a non-magnetic state for Ni. Gd_1+xNi₄Mg_1?x (x ≈ 0.12) orders antiferromagnetically at a Néel temperature of T_N = 4.6(5) K. Resistivity measurements reflect the metallic nature of these compounds.     

Comparative numerical studies of projectile impacts on plain and steel-fibre reinforced concrete

The enhanced energy absorption characteristics of fibre-reinforced concrete, compared to plain concrete, has in experimentally studies been shown to improve the projectile resistance and motivate its increased usage in protective structures. However, the high cost of undertaking experiments and the high parameter variation and dependency of the experimental setups and results, respectively, make it difficult to draw generic conclusions of how the addition and increased amount of fibres affects the local damage caused by projectile impact, which motivates the use of numerical simulations to study this. The numerical hydrocode AUTODYN was used in a qualitative study of how the addition of different amounts of fibres, modelled as different post-crack relations, influence the depth of penetration and crater formation on the front and rear face of a concrete target. Fibres added to the concrete mix had a minor influence on the depth of penetration while the crater size on both front and rear faces of the target decreases. The crack propagation beyond the crater on the front face was also reduced when fibres were added to the concrete. An increased amount of fibres in the concrete showed no effect on the size of the front-face crater, but led to further decreased size of the crater on the rear face of the concrete cylinder. It is concluded that the scabbing crater can be reduced in size and prevented by usage of fibre-reinforced concrete even if the depth of penetration is only slightly less than to penetration depth in plain concrete.