1,408,132 research outputs found
High-frequency oscillations in low-dimensional conductors and semiconductor superlattices induced by current in stack direction
A narrow energy band of the electronic spectrum in some direction in
low-dimensional crystals may lead to a negative differential conductance and
N-shaped I-V curve that results in an instability of the uniform stationary
state. A well-known stable solution for such a system is a state with electric
field domain. We have found a uniform stable solution in the region of negative
differential conductance. This solution describes uniform high-frequency
voltage oscillations. Frequency of the oscillation is determined by antenna
properties of the system. The results are applicable also to semiconductor
superlattices.Comment: 8 pages, 3 figure
Spiking Neural P Systems with Structural Plasticity: Attacking the Subset Sum Problem
Spiking neural P systems with structural plasticity (in short,
SNPSP systems) are models of computations inspired by the function and
structure of biological neurons. In SNPSP systems, neurons can create
or delete synapses using plasticity rules. We report two families of solutions:
a non-uniform and a uniform one, to the NP-complete problem
Subset Sum using SNPSP systems. Instead of the usual rule-level nondeterminism
(choosing which rule to apply) we use synapse-level nondeterminism
(choosing which synapses to create or delete). The nondeterminism
due to plasticity rules have the following improvements from a
previous solution: in our non-uniform solution, plasticity rules allowed
for a normal form to be used (i.e. without forgetting rules or rules with
delays, system is simple, only synapse-level nondeterminism); in our uniform
solution the number of neurons and the computation steps are
reduced.Ministerio de Economía y Competitividad TIN2012-3743
Stability Analysis of Optimal Velocity Model for Traffic and Granular Flow under Open Boundary Condition
We analyzed the stability of the uniform flow solution in the optimal
velocity model for traffic and granular flow under the open boundary condition.
It was demonstrated that, even within the linearly unstable region, there is a
parameter region where the uniform solution is stable against a localized
perturbation. We also found an oscillatory solution in the linearly unstable
region and its period is not commensurate with the periodicity of the car index
space. The oscillatory solution has some features in common with the
synchronized flow observed in real traffic.Comment: 4 pages, 6 figures. Typos removed. To appear in J. Phys. Soc. Jp
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