2,489 research outputs found
Foam generator Patent
Plastic foam generator for space vehicle instrument payload package flotation in water landin
Shifting donor-acceptor photoluminescence in N-doped ZnO
We have grown nitrogen-doped ZnO films grown by two kinds of epitaxial
methods on lattice-matched ScAlMgO substrates. We measured the
photoluminescence (PL) of the two kinds of ZnO:N layers in the
donor-acceptor-pair transition region. The analysis of excitation-intensity
dependence of the PL peak shift with a fluctuation model has proven that our
observed growth-technique dependence was explained in terms of the
inhomogeneity of charged impurity distribution. It was found that the
inhomogeneity in the sample prepared with the process showing better electrical
property was significantly smaller in spite of the similar nitrogen
concentration. The activation energy of acceptor has been evaluated to be
meV, which is independent of the nitrogen concentration.Comment: 4 pages, 3 figures, 1 table, RevTeX4, to appear in the July issue of
J. Phys. Soc. Jp
Checkerboard Julia Sets for Rational Maps
In this paper, we consider the family of rational maps \F(z) = z^n +
\frac{\la}{z^d}, where , , and\la \in \bbC. We consider
the case where \la lies in the main cardioid of one of the principal
Mandelbrot sets in these families. We show that the Julia sets of these maps
are always homeomorphic. However, two such maps \F and are conjugate
on these Julia sets only if the parameters at the centers of the given
cardioids satisfy \mu = \nu^{j(d+1)}\la or \mu = \nu^{j(d+1)}\bar{\la}
where j \in \bbZ and is an root of unity. We define a
dynamical invariant, which we call the minimal rotation number. It determines
which of these maps are are conjugate on their Julia sets, and we obtain an
exact count of the number of distinct conjugacy classes of maps drawn from
these main cardioids.Comment: 25 pages, 14 figures; Changes since March 19 version: added nine
figures, fixed one proof, added a section on a group actio
Hamiltonian Formalism of the de-Sitter Invariant Special Relativity
Lagrangian of the Einstein's special relativity with universal parameter
() is invariant under Poincar\'e transformation which preserves
Lorentz metric . The has been extended to be
one which is invariant under de Sitter transformation that preserves so called
Beltrami metric . There are two universal parameters and in
this Special Relativity (denote it as ). The
Lagrangian-Hamiltonian formulism of is formulated in this
paper. The canonic energy, canonic momenta, and 10 Noether charges
corresponding to the space-time's de Sitter symmetry are derived. The canonical
quantization of the mechanics for -free particle is
performed. The physics related to it is discussed.Comment: 24 pages, no figur
Confinement and Quantization Effects in Mesoscopic Superconducting Structures
We have studied quantization and confinement effects in nanostructured
superconductors. Three different types of nanostructured samples were
investigated: individual structures (line, loop, dot), 1-dimensional (1D)
clusters of loops and 2D clusters of antidots, and finally large lattices of
antidots. Hereby, a crossover from individual elementary "plaquettes", via
clusters, to huge arrays of these elements, is realized. The main idea of our
study was to vary the boundary conditions for confinement of the
superconducting condensate by taking samples of different topology and, through
that, modifying the lowest Landau level E_LLL(H). Since the critical
temperature versus applied magnetic field T_c(H) is, in fact, E_LLL(H) measured
in temperature units, it is varied as well when the sample topology is changed
through nanostructuring. We demonstrate that in all studied nanostructured
superconductors the shape of the T_c(H) phase boundary is determined by the
confinement topology in a unique way.Comment: 28 pages, 19 EPS figures, uses LaTeX's aipproc.sty, contribution to
Euroschool on "Superconductivity in Networks and Mesoscopic Systems", held in
Siena, Italy (8-20 september 1997
From the Complete Yang Model to Snyder's Model, de Sitter Special Relativity and Their Duality
By means of Dirac procedure, we re-examine Yang's quantized space-time model,
its relation to Snyder's model, the de Sitter special relativity and their
UV-IR duality. Starting from a dimensionless dS_5-space in a 5+1-d Mink-space a
complete Yang model at both classical and quantum level can be presented and
there really exist Snyder's model, the dS special relativity and the duality.Comment: 7 papge
Ratchet Cellular Automata
In this work we propose a ratchet effect which provides a general means of
performing clocked logic operations on discrete particles, such as single
electrons or vortices. The states are propagated through the device by the use
of an applied AC drive. We numerically demonstrate that a complete logic
architecture is realizable using this ratchet. We consider specific
nanostructured superconducting geometries using superconducting materials under
an applied magnetic field, with the positions of the individual vortices in
samples acting as the logic states. These devices can be used as the building
blocks for an alternative microelectronic architecture.Comment: 4 pages, 3 figure
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