18,521 research outputs found
Work Function of Single-wall Silicon Carbide Nanotube
Using first-principles calculations, we study the work function of single
wall silicon carbide nanotube (SiCNT). The work function is found to be highly
dependent on the tube chirality and diameter. It increases with decreasing the
tube diameter. The work function of zigzag SiCNT is always larger than that of
armchair SiCNT. We reveal that the difference between the work function of
zigzag and armchair SiCNT comes from their different intrinsic electronic
structures, for which the singly degenerate energy band above the Fermi level
of zigzag SiCNT is specifically responsible. Our finding offers potential
usages of SiCNT in field-emission devices.Comment: 3 pages, 3 figure
Fuzzy logic and mathematical morphology
In this report we investigate the general theory of grey-scale morphology within the framework of complete lattices and fuzzy logic. This includes grey-scale granulometries, hit-or-miss operators for grey-scale images, rank operators, and connected operators. We also show that the Matheron's representation theory does not hold for general grey-scale images and we present some results related to the representation theory. Besides these, in this report, we put forward a new approach to fuzzy morphology through the extension of infimum, supremum, and conjunction
Rank-frequency relation for Chinese characters
We show that the Zipf's law for Chinese characters perfectly holds for
sufficiently short texts (few thousand different characters). The scenario of
its validity is similar to the Zipf's law for words in short English texts. For
long Chinese texts (or for mixtures of short Chinese texts), rank-frequency
relations for Chinese characters display a two-layer, hierarchic structure that
combines a Zipfian power-law regime for frequent characters (first layer) with
an exponential-like regime for less frequent characters (second layer). For
these two layers we provide different (though related) theoretical descriptions
that include the range of low-frequency characters (hapax legomena). The
comparative analysis of rank-frequency relations for Chinese characters versus
English words illustrates the extent to which the characters play for Chinese
writers the same role as the words for those writing within alphabetical
systems.Comment: To appear in European Physical Journal B (EPJ B), 2014 (22 pages, 7
figures
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