6,957 research outputs found
Signal modeling with Non Uniform Topology lattice filters
This article presents a new class of constrained and specialized Auto-Regressive (AR) processes. They are derived from lattice filters where some reflection coefficients are forced to zero at a priori locations. Optimizing the filter topology allows to build parametric spectral models that have a greater number of poles than the number of parameters needed to describe their location. These NUT (Non-Uniform Topology) models are assessed by evaluating the reduction of modeling error with respect to conventional AR models
The Kinetic Basis of Morphogenesis
It has been shown recently (Shalygo, 2014) that stationary and dynamic
patterns can arise in the proposed one-component model of the analog
(continuous state) kinetic automaton, or kinon for short, defined as a
reflexive dynamical system with active transport. This paper presents
extensions of the model, which increase further its complexity and tunability,
and shows that the extended kinon model can produce spatio-temporal patterns
pertaining not only to pattern formation but also to morphogenesis in real
physical and biological systems. The possible applicability of the model to
morphogenetic engineering and swarm robotics is also discussed.Comment: 8 pages. Submitted to the 13th European Conference on Artificial Life
(ECAL-2015) on March 10, 2015. Accepted on April 28, 201
RF and Microwave Band-Pass Passive Filters for Mobile Transceivers with a Focus on BAW Technology
International audienc
Efficient Synthesis of Room Acoustics via Scattering Delay Networks
An acoustic reverberator consisting of a network of delay lines connected via
scattering junctions is proposed. All parameters of the reverberator are
derived from physical properties of the enclosure it simulates. It allows for
simulation of unequal and frequency-dependent wall absorption, as well as
directional sources and microphones. The reverberator renders the first-order
reflections exactly, while making progressively coarser approximations of
higher-order reflections. The rate of energy decay is close to that obtained
with the image method (IM) and consistent with the predictions of Sabine and
Eyring equations. The time evolution of the normalized echo density, which was
previously shown to be correlated with the perceived texture of reverberation,
is also close to that of IM. However, its computational complexity is one to
two orders of magnitude lower, comparable to the computational complexity of a
feedback delay network (FDN), and its memory requirements are negligible
Real-time dynamic articulations in the 2-D waveguide mesh vocal tract model
Time domain articulatory vocal tract modeling in one-dimensional (1-D) is well established. Previous studies into two-dimensional (2-D) simulation of wave propagation in the vocal tract have shown it to present accurate static vowel synthesis. However, little has been done to demonstrate how such a model might accommodate the dynamic tract shape changes necessary in modeling speech. Two methods of applying the area function to the 2-D digital waveguide mesh vocal tract model are presented here. First, a method based on mapping the cross-sectional area onto the number of waveguides across the mesh, termed a widthwise mapping approach is detailed. Discontinuity problems associated with the dynamic manipulation of the model are highlighted. Second, a new method is examined that uses a static-shaped rectangular mesh with the area function translated into an impedance map which is then applied to each waveguide. Two approaches for constructing such a map are demonstrated; one using a linear impedance increase to model a constriction to the tract and another using a raised cosine function. Recommendations are made towards the use of the cosine method as it allows for a wider central propagational channel. It is also shown that this impedance mapping approach allows for stable dynamic shape changes and also permits a reduction in sampling frequency leading to real-time interaction with the model
Optimization and experimental validation of stiff porous phononic plates for widest complete bandgap of mixed fundamental guided wave modes
Phononic crystal plates (PhPs) have promising application in manipulation of guided waves
for design of low-loss acoustic devices and built-in acoustic metamaterial lenses in plate
structures. The prominent feature of phononic crystals is the existence of frequency bandgaps
over which the waves are stopped, or are resonated and guided within appropriate
defects. Therefore, maximized bandgaps of PhPs are desirable to enhance their phononic
controllability. Porous PhPs produced through perforation of a uniform background plate,
in which the porous interfaces act as strong reflectors of wave energy, are relatively easy to
produce. However, the research in optimization of porous PhPs and experimental validation
of achieved topologies has been very limited and particularly focused on bandgaps
of flexural (asymmetric) wave modes. In this paper, porous PhPs are optimized through
an efficient multiobjective genetic algorithm for widest complete bandgap of mixed fundamental
guided wave modes (symmetric and asymmetric) and maximized stiffness. The
Pareto front of optimization is analyzed and variation of bandgap efficiency with respect
to stiffness is presented for various optimized topologies. Selected optimized topologies
from the stiff and compliant regimes of Pareto front are manufactured by water-jetting
an aluminum plate and their promising bandgap efficiency is experimentally observed.
An optimized Pareto topology is also chosen and manufactured by laser cutting a
Plexiglas (PMMA) plate, and its performance in self-collimation and focusing of guided
waves is verified as compared to calculated dispersion properties
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