1,512 research outputs found
Electrically-induced n-i-p junctions in multiple graphene layer structures
The Fermi energies of electrons and holes and their densities in different
graphene layers (GLs) in the n- and p-regions of the electrically induced n-i-p
junctions formed in multiple-GL structures are calculated both numerically and
using a simplified analytical model. The reverse current associated with the
injection of minority carriers through the n- and p-regions in the
electrically-induced n-i-p junctions under the reverse bias is calculated as
well. It is shown that in the electrically-induced n-i-p junctions with
moderate numbers of GLs the reverse current can be substantially suppressed.
Hence, multiple-GL structures with such n-i-p junctions can be used in
different electron and optoelectron devices.Comment: 7 pages, 6 figure
EERTREE: An Efficient Data Structure for Processing Palindromes in Strings
We propose a new linear-size data structure which provides a fast access to
all palindromic substrings of a string or a set of strings. This structure
inherits some ideas from the construction of both the suffix trie and suffix
tree. Using this structure, we present simple and efficient solutions for a
number of problems involving palindromes.Comment: 21 pages, 2 figures. Accepted to IWOCA 201
Comparison of LZ77-type Parsings
We investigate the relations between different variants of the LZ77 parsing
existing in the literature. All of them are defined as greedily constructed
parsings encoding each phrase by reference to a string occurring earlier in the
input. They differ by the phrase encodings: encoded by pairs (length + position
of an earlier occurrence) or by triples (length + position of an earlier
occurrence + the letter following the earlier occurring part); and they differ
by allowing or not allowing overlaps between the phrase and its earlier
occurrence. For a given string of length over an alphabet of size ,
denote the numbers of phrases in the parsings allowing (resp., not allowing)
overlaps by (resp., ) for "pairs", and by (resp.,
) for "triples". We prove the following bounds and provide series of
examples showing that these bounds are tight:
and
;
and .Comment: 6 page
Almost overlap-free words and the word problem for the free Burnside semigroup satisfying x^2=x^3
In this paper we investigate the word problem of the free Burnside semigroup
satisfying x^2=x^3 and having two generators. Elements of this semigroup are
classes of equivalent words. A natural way to solve the word problem is to
select a unique "canonical" representative for each equivalence class. We prove
that overlap-free words and so-called almost overlap-free words (this notion is
some generalization of the notion of overlap-free words) can serve as canonical
representatives for corresponding equivalence classes. We show that such a word
in a given class, if any, can be efficiently found. As a result, we construct a
linear-time algorithm that partially solves the word problem for the semigroup
under consideration.Comment: 33 pages, submitted to Internat. J. of Algebra and Compu
Nonlinear charge injection in organic field-effect transistors
Transport properties of a series of poly(3-hexylthiophene) organic field
effect transistors with Cr, Cu and Au source/drain electrodes were examined
over a broad temperature range. The current-voltage characteristics of the
injecting contacts are extracted from the dependence of conductance on channel
length. With reasonable parameters, a model of hopping injection into a
disordered density of localized states, with emphasis on the primary injection
event, agrees well with the field and the temperature dependence of the data
over a broad range of temperatures and gate voltages.Comment: 7 pages, 7 figures, sub. to J. Appl. Phy
On the Combinatorics of Palindromes and Antipalindromes
We prove a number of results on the structure and enumeration of palindromes
and antipalindromes. In particular, we study conjugates of palindromes,
palindromic pairs, rich words, and the counterparts of these notions for
antipalindromes.Comment: 13 pages/ submitted to DLT 201
- …