4,596 research outputs found
Reply to ``Comment on ``Lateral Casimir Force beyond the Proximity Force Approximation'' ''
We reply to the comment arXiv:quant-ph/0702060 on our letter
arXiv:quant-ph/0603120 [Phys. Rev. Lett. 96, 100402 (2006)]Comment: 1 pag
Particle Creation by a Moving Boundary with Robin Boundary Condition
We consider a massless scalar field in 1+1 dimensions satisfying a Robin
boundary condition (BC) at a non-relativistic moving boundary. We derive a
Bogoliubov transformation between input and output bosonic field operators,
which allows us to calculate the spectral distribution of created particles.
The cases of Dirichlet and Neumann BC may be obtained from our result as
limiting cases. These two limits yield the same spectrum, which turns out to be
an upper bound for the spectra derived for Robin BC. We show that the particle
emission effect can be considerably reduced (with respect to the
Dirichlet/Neumann case) by selecting a particular value for the oscillation
frequency of the boundary position
Geração de mapas georreferenciados para visualização de dados de campo para auxílio na tomada de decisão em irrigação de precisão.
Este trabalho teve como objetivo desenvolver um aplicativo computacional capaz de gerar mapas georreferenciados úteis para a tomada de decisão em irrigação de precisão. Para tanto, foram utilizadas as bibliotecas TerraLib e SOMCode, ambas de código aberto e escritas na linguagem C++, desenvolvidas pelo Instituto Nacional de Pesquisas Espaciais (INPE) e pela Embrapa Tabuleiros Costeiros (CPATC), respectivamente. Os dados utilizados para a geração desses mapas foram obtidos por uma grade de sensores de uma unidade piloto da plataforma Irrigap, desenvolvida pela Embrapa Instrumentação Agropecuária (CNPDIA), dados esses referentes a medidas horárias de umidade e temperatura do solo e temperatura do ar. Diferentes métodos de interpolação foram utilizados, com o intuito de verificar qual a melhor maneira de se gerar mapas que possibilitem a visualização de áreas com o mesmo comportamento com relação às variáveis de solo e climatológicas, as chamadas zonas de manejo agrícolas. Os resultados obtidos mostraram que é possível a identificação dessas zonas, desde que sejam utilizados os algoritmos corretos para cada situação. Além disso, aplicativos para a geração de mapas temáticos utilizando dados reais podem se tornar importantes para a tomada de decisão em agricultura de precisão, proporcionando benefícios como a economia de água e energia durante o período de irrigação
The lateral Casimir force beyond the proximity force approximation: a nontrivial interplay between geometry and quantum vacuum
The lateral Casimir force between two corrugated metallic plates makes possible a study of the nontrivial interplay of geometry and Casimir effect appearing beyond the regime of validity of the Proximity Force Approximation (PFA). Quantitative evaluations can be obtained by using scattering theory in a perturbative expansion valid when the corrugation amplitudes are smaller than the three other length scales: the mean separation distance of the plates, the corrugation period \lambda_\C and the plasma wavelength . Within this perturbative expansion, evaluations are obtained for arbitrary relative values of , \lambda_\C and while limiting cases, some of them already known, are recovered when these values obey some specific orderings. The consequence of these results for comparison with existing experiments is discussed in the end of the paper
Hamiltonian symplectic embedding of the massive noncommutative U(1) Theory
We show that the massive noncommutative U(1) theory is embedded in a gauge
theory using an alternative systematic way, which is based on the symplectic
framework. The embedded Hamiltonian density is obtained after a finite number
of steps in the iterative symplectic process, oppositely to the result proposed
using the BFFT formalism. This alternative formalism of embedding shows how to
get a set of dynamically equivalent embedded Hamiltonian densities.Comment: 16 pages, no figures, revtex4, corrected version, references
additione
Lateral Casimir force beyond the Proximity Force Approximation
We argue that the appropriate variable to study a non trivial geometry
dependence of the Casimir force is the lateral component of the Casimir force,
which we evaluate between two corrugated metallic plates outside the validity
of the Proximity Force Approximation (PFA). The metallic plates are described
by the plasma model, with arbitrary values for the plasma wavelength, the plate
separation and the corrugation period, the corrugation amplitude remaining the
smallest length scale. Our analysis shows that in realistic experimental
situations the Proximity Force Approximation overestimates the force by up to
30%.Comment: 4 pages. Identical to v1, which was accidentally replaced by a
different paper (quant-ph/0610026
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