6,682 research outputs found
Discrete-Time Fractional Variational Problems
We introduce a discrete-time fractional calculus of variations on the time
scale , . First and second order necessary optimality
conditions are established. Examples illustrating the use of the new
Euler-Lagrange and Legendre type conditions are given. They show that solutions
to the considered fractional problems become the classical discrete-time
solutions when the fractional order of the discrete-derivatives are integer
values, and that they converge to the fractional continuous-time solutions when
tends to zero. Our Legendre type condition is useful to eliminate false
candidates identified via the Euler-Lagrange fractional equation.Comment: Submitted 24/Nov/2009; Revised 16/Mar/2010; Accepted 3/May/2010; for
publication in Signal Processing
Melnikov analysis in nonsmooth differential systems with nonlinear switching manifold
We study the family of piecewise linear differential systems in the plane
with two pieces separated by a cubic curve. Our main result is that 7 is a
lower bound for the Hilbert number of this family. In order to get our main
result, we develop the Melnikov functions for a class of nonsmooth differential
systems, which generalizes, up to order 2, some previous results in the
literature. Whereas the first order Melnikov function for the nonsmooth case
remains the same as for the smooth one (i.e. the first order averaged function)
the second order Melnikov function for the nonsmooth case is different from the
smooth one (i.e. the second order averaged function). We show that, in this
case, a new term depending on the jump of discontinuity and on the geometry of
the switching manifold is added to the second order averaged function
Resposta diferencial de genótipos de sorgo para tolerância ao alumÃnio em solução nutritiva.
Neste trabalho utilizou-se de uma tecnica de solucao nutritiva para identificar, dentre 391 linhagens de sorgo (BAG-Sorgo; 181), CNPMS: 71, SEPON/ICRISAT: 17 e Sacarino: 122, os genotipos que apresentam tolerancia ao aluminio. A avaliacao do comportamento diferencial dessas linhagens baseou-se no crescimento da raiz seminal primaria de plantas jovens de sorgo, em solucao nutritiva contendo niveis variados de Al (0,0, 2,25 e 4,5 mg de Al/1 para sorgo granifero e 0,0, 2,25 e 5,0 mg de Al/1 para sorgo sacarino). A caracteristica usada para a comparacao entre genotipos foi o Comprimento Relativo da Raiz Seminal (CRSS = CRS + AL/CRS - Al, onde CRS = comprimento da Raiz Seminal). Baseando-se na distribuicao percentual dos valores de CRRS obtidos para as diferentes linhagens e nos valores de CRRS encontrados para os materiais controles SC 298 (sensivel ao Al) e SC 283 (tolerante ao Al) tres classes de resposta ao aluminio foram definidas: Sensivel (CRRS 0,70). Dentre os materiais avaliados as seguintes linhagens apresentaram tolerancia aos niveis de 4,5 ou 5,0 mg de Al/1: IS 3625, IS 7173 C (SC 283), IS 12666, 5DX61/6/2, 3DX57/1/1910, 156-P-5-Serere-1, 9DX9/11, Brandes, MN 4004 e MN 1204
Reptilia, Squamata, Tropiduridae, <i>Stenocercus sinesaccus</i> Torres–Carvajal, 2005: Distribution extension
The present study reports the easternmost known record for the tropidurid lizard Stenocercussinesaccus Torres–Carvajal, 2005, at Floresta Nacional de Silvânia, state of Goiás, Brazil, in a transition areabetween cerrado sensu strictu and gallery fores
Dermoscopic and Reflectance Confocal Microscopic Presentation of Relapsing Eccrine Porocarcinoma
info:eu-repo/semantics/publishedVersio
Registo da avaliação da dor em sistema de informação: um projeto em desenvolvimento
Poster apresentado nas I Jornadas do Mestrado em Enfermagem de Saúde Infantil e Pediatria, organizadas pela Escola Superior de Enfermagem do Port
Thermal difference reflectivity of tilted 2D Dirac materials
Deviation from perfect conical dispersion in Dirac materials, such as the
presence of mass or tilting, enhances control and directionality of electronic
transport. To identify these signatures, we analyze the thermal derivative
spectra of optical reflectivity in doped massive tilted Dirac systems. The
density of states and chemical potential are determined as preliminary steps to
calculate the optical conductivity tensor at finite temperature using thermal
convolution. Changes in reflection caused by temperature variations enable
clear identification of critical frequencies in the optical response. By
measuring these spectral features in the thermoderivative spectrum, energy gaps
and band structure tilting can be determined. A comparison is presented between
the spectra of various low-energy Dirac Hamiltonians. Our findings suggest that
thermal difference spectroscopy holds promise as a valuable technique for
probing interband transitions of 2D Dirac fermion
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