On the beneficial effect of noise in vertex localization

A theoretical and experimental analysis related to the effect of noise in the task of vertex identication in unknown shapes is presented. Shapes are seen as real functions of their closed boundary. An alternative global perspective of curvature is examined providing insight into the process of noise- enabled vertex localization. The analysis reveals that noise facilitates in the localization of certain vertices. The concept of noising is thus considered and a relevant global method for localizing Global Vertices is investigated in relation to local methods under the presence of increasing noise. Theoretical analysis reveals that induced noise can indeed help localizing certain vertices if combined with global descriptors. Experiments with noise and a comparison to localized methods validate the theoretical results

CRYSTAL-STRUCTURE OF PREHNITE FROM KOMIZA

The criystal structure of prehnite (Ca2(Al,Fe) (OH)2 [ Si3AlO10])from Komi\u17ea (Yugoslavia) has been refined in the space group P2cm (a=4,646(2) \u1fa, b= 5.491(3) \u1fa, c=18.52(3) \u1fa, Z=2). Si and Al showed a completely ordered distribution in the structure. The obtained Fe-Alsubstitution for the octahedral coordination is 17%. No monoclinic domains could be observed in the crystals. Laue photographs show that the splitting of the diffraction maxima in prehnite from Komi\u17ea is due to lattice rotation around the direction of the b axis