1,852 research outputs found
Two-scale convergence for locally-periodic microstructures and homogenization of plywood structures
The introduced notion of locally-periodic two-scale convergence allows to
average a wider range of microstructures, compared to the periodic one. The
compactness theorem for the locally-periodic two-scale convergence and the
characterisation of the limit for a sequence bounded in are
proven. The underlying analysis comprises the approximation of functions, which
periodicity with respect to the fast variable depends on the slow variable, by
locally-periodic functions, periodic in subdomains smaller than the considered
domain, but larger than the size of microscopic structures. The developed
theory is applied to derive macroscopic equations for a linear elasticity
problem defined in domains with plywood structures.Comment: 22 pages, 4 figure
Thin waveguides with Robin boundary conditions
We consider the Laplace operator in a thin three dimensional tube with a
Robin type condition on its boundary and study, asymptotically, the spectrum of
such operator as the diameter of the tube's cross section becomes
infinitesimal. In contrast with the Dirichlet condition case, we evidence
different behaviors depending on a symmetry criterium for the fundamental mode
in the cross section. If that symmetry condition fails, then we prove the
localization of lower energy levels in the vicinity of the minimum point of a
suitable function on the tube's axis depending on the curvature and the
rotation angle. In the symmetric case, the behavior of lower energy modes is
shown to be ruled by a one dimensional Sturm-Liouville problem involving an
effective potential given in explicit form
Locally periodic unfolding method and two-scale convergence on surfaces of locally periodic microstructures
In this paper we generalize the periodic unfolding method and the notion of
two-scale convergence on surfaces of periodic microstructures to locally
periodic situations. The methods that we introduce allow us to consider a wide
range of non-periodic microstructures, especially to derive macroscopic
equations for problems posed in domains with perforations distributed
non-periodically. Using the methods of locally periodic two-scale convergence
(l-t-s) on oscillating surfaces and the locally periodic (l-p) boundary
unfolding operator, we are able to analyze differential equations defined on
boundaries of non-periodic microstructures and consider non-homogeneous Neumann
conditions on the boundaries of perforations, distributed non-periodically
Experiences with digital processing of images at INPE
Four different research experiments with digital image processing at INPE will be described: (1) edge detection by hypothesis testing; (2) image interpolation by finite impulse response filters; (3) spatial feature extraction methods in multispectral classification; and (4) translational image registration by sequential tests of hypotheses
A Fabry-Perot interferometer with quantum mirrors: nonlinear light transport and rectification
Optical transport represents a natural route towards fast communications, and
it is currently used in large scale data transfer. The progressive
miniaturization of devices for information processing calls for the microscopic
tailoring of light transport and confinement at length scales appropriate for
the upcoming technologies. With this goal in mind, we present a theoretical
analysis of a one-dimensional Fabry-Perot interferometer built with two highly
saturable nonlinear mirrors: a pair of two-level systems. Our approach captures
non-linear and non-reciprocal effects of light transport that were not reported
previously. Remarkably, we show that such an elementary device can operate as a
microscopic integrated optical rectifier
Evaluation of entropy and JM-distance criterions as features selection methods using spectral and spatial features derived from LANDSAT images
A study area near Ribeirao Preto in Sao Paulo state was selected, with predominance in sugar cane. Eight features were extracted from the 4 original bands of LANDSAT image, using low-pass and high-pass filtering to obtain spatial features. There were 5 training sites in order to acquire the necessary parameters. Two groups of four channels were selected from 12 channels using JM-distance and entropy criterions. The number of selected channels was defined by physical restrictions of the image analyzer and computacional costs. The evaluation was performed by extracting the confusion matrix for training and tests areas, with a maximum likelihood classifier, and by defining performance indexes based on those matrixes for each group of channels. Results show that in spatial features and supervised classification, the entropy criterion is better in the sense that allows a more accurate and generalized definition of class signature. On the other hand, JM-distance criterion strongly reduces the misclassification within training areas
Equilibrium and Disorder-induced behavior in Quantum Light-Matter Systems
We analyze equilibrium properties of coupled-doped cavities described by the
Jaynes-Cummings- Hubbard Hamiltonian. In particular, we characterize the
entanglement of the system in relation to the insulating-superfluid phase
transition. We point out the existence of a crossover inside the superfluid
phase of the system when the excitations change from polaritonic to purely
photonic. Using an ensemble statistical approach for small systems and
stochastic-mean-field theory for large systems we analyze static disorder of
the characteristic parameters of the system and explore the ground state
induced statistics. We report on a variety of glassy phases deriving from the
hybrid statistics of the system. On-site strong disorder induces insulating
behavior through two different mechanisms. For disorder in the light-matter
detuning, low energy cavities dominate the statistics allowing the excitations
to localize and bunch in such cavities. In the case of disorder in the light-
matter coupling, sites with strong coupling between light and matter become
very significant, which enhances the Mott-like insulating behavior. Inter-site
(hopping) disorder induces fluidity and the dominant sites are strongly coupled
to each other.Comment: about 10 pages, 12 figure
The (mis)use of graphs insights into the portuguese companies´ annual reports
Graphs area suitable format for summarizing and disclosinginformation in annual reports given thatinvestors,and other addressees of graphs, may lack of the time required to fully analysethe information. Therefore, graphs should be reliable,accurateand free from material distortions. This Work Project aims to make aware of the importance that graphs have both for the report’s usersand the companies themselves. Moreover, this project investigates the potential roots of graphical distortions. The findings suggestthatthe correlation between the level of graph distortion in Portugal and the Board of Directors ismoderate, although not significant
A system dynamics-based framework for examining Circular Economy transitions
Funding Information: The authors would like to sincerely thank the Higher Education Personnel Improvement Coordination ( CAPES ), from Brazil, for financially supporting this research. CENSE is supported by the Portuguese Foundation for Science and Technology ( FCT ) through the strategic project UIDB/04085/2020. Publisher Copyright: © 2021 The AuthorsDecision-makers in the public policy and business arenas need tools to deal with multiple sources of complexity in Circular Economy (CE) transitions. System Dynamics (SD) facilitates coping with increased complexity by enabling closed-loop thinking via identifying the causal structures underlying behaviour and permitting to proactively experiment with the system through simulation. This research aims to propose and test an SD-based framework for examining CE transitions to supporting decision-making at the micro-, meso-, and macro-levels. Two inductive model-based cases studies led to formalising the framework, finally tested in a third deductive model-based case study. The framework is built upon the well-known stages for building SD simulation models and complemented with domain-specific activities, guiding questions, and expected outcomes when examining CE transitions. The SD-based framework is the first modelling-oriented prescriptive approach to help researchers and practitioners examining CE transitions on their journeys to understand and facilitate changes through SD simulation models.publishersversionpublishe
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