2,570 research outputs found
A model for Faraday pilot waves over variable topography
Couder and Fort discovered that droplets walking on a vibrating bath possess
certain features previously thought to be exclusive to quantum systems. These
millimetric droplets synchronize with their Faraday wavefield, creating a
macroscopic pilot-wave system. In this paper we exploit the fact that the waves
generated are nearly monochromatic and propose a hydrodynamic model capable of
quantitatively capturing the interaction between bouncing drops and a variable
topography. We show that our reduced model is able to reproduce some important
experiments involving the drop-topography interaction, such as non-specular
reflection and single-slit diffraction
Planewave density interpolation methods for 3D Helmholtz boundary integral equations
This paper introduces planewave density interpolation methods for the
regularization of weakly singular, strongly singular, hypersingular and nearly
singular integral kernels present in 3D Helmholtz surface layer potentials and
associated integral operators. Relying on Green's third identity and pointwise
interpolation of density functions in the form of planewaves, these methods
allow layer potentials and integral operators to be expressed in terms of
integrand functions that remain smooth (at least bounded) regardless the
location of the target point relative to the surface sources. Common
challenging integrals that arise in both Nystr\"om and boundary element
discretization of boundary integral equation, can then be numerically evaluated
by standard quadrature rules that are irrespective of the kernel singularity.
Closed-form and purely numerical planewave density interpolation procedures are
presented in this paper, which are used in conjunction with Chebyshev-based
Nystr\"om and Galerkin boundary element methods. A variety of numerical
examples---including problems of acoustic scattering involving multiple
touching and even intersecting obstacles, demonstrate the capabilities of the
proposed technique
An adaptive educational system for higher education
The main objective of an Adaptive System is to adequate its relation with the user (content
presentation, navigation, interface, etc.) according to a predefined but updatable model of the user
that reflects his objectives, preferences, knowledge and competences [Brusilovsky, 2001], [De Bra,
2004]. For Educational Adaptive Systems, the emphasis is placed on the student knowledge in the
domain application and learning style, to allow him to reach the learning objectives proposed for his
training [Chepegin, 2004]. In Educational AHS, the User Model (UM), or Student Model, has increased
relevance: when the student reaches the objectives of the course, the system must be able to readapt,
for example, to his knowledge [Brusilovsky, 2001].
Learning Styles are understood as something that intent to define models of how given person
learns. Generally it is understood that each person has a Learning Style different and preferred with
the objective of achieving better results. Some case studies have proposed that teachers should
assess the learning styles of their students and adapt their classroom and methods to best fit each
student's learning style [Kolb, 2005], [Martins, 2008]. The learning process must take into
consideration the individual cognitive and emotional parts of the student. In summary each Student
is unique so the Student personal progress must be monitored and teaching shoul not be not
generalized and repetitive [Jonassen, 1991], [Martins, 2008].
The aim of this paper is to present an Educational Adaptive Hypermedia Tool based on Progressive
Assessment
Harmonic density interpolation methods for high-order evaluation of Laplace layer potentials in 2D and 3D
We present an effective harmonic density interpolation method for the
numerical evaluation of singular and nearly singular Laplace boundary integral
operators and layer potentials in two and three spatial dimensions. The method
relies on the use of Green's third identity and local Taylor-like
interpolations of density functions in terms of harmonic polynomials. The
proposed technique effectively regularizes the singularities present in
boundary integral operators and layer potentials, and recasts the latter in
terms of integrands that are bounded or even more regular, depending on the
order of the density interpolation. The resulting boundary integrals can then
be easily, accurately, and inexpensively evaluated by means of standard
quadrature rules. A variety of numerical examples demonstrate the effectiveness
of the technique when used in conjunction with the classical trapezoidal rule
(to integrate over smooth curves) in two-dimensions, and with a Chebyshev-type
quadrature rule (to integrate over surfaces given as unions of non-overlapping
quadrilateral patches) in three-dimensions
Theory of weakly nonlinear self sustained detonations
We propose a theory of weakly nonlinear multi-dimensional self sustained
detonations based on asymptotic analysis of the reactive compressible
Navier-Stokes equations. We show that these equations can be reduced to a model
consisting of a forced, unsteady, small disturbance, transonic equation and a
rate equation for the heat release. In one spatial dimension, the model
simplifies to a forced Burgers equation. Through analysis, numerical
calculations and comparison with the reactive Euler equations, the model is
demonstrated to capture such essential dynamical characteristics of detonations
as the steady-state structure, the linear stability spectrum, the
period-doubling sequence of bifurcations and chaos in one-dimensional
detonations and cellular structures in multi- dimensional detonations
O modelo de código de responsabilidade profissional da Associação Americana de Advogados = American Bar Association model code of professional responsability
Tece um breve percurso histórico da adoção de normas éticas para o exercício da profissão de advogado nos Estados Unidos desde 1836 até o presente. Analisa a criação da Associação Americana de Advogados, que facilitou a codificação dessas normas em nível nacional e estimulou a sua adoção pelos diversos órgãos federais e estaduais
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