Search results for "LET"
showing 10 items of 23489 documents
A Fixed Domain Approach in Shape Optimization Problems with Neumann Boundary Conditions
2008
Fixed domain methods have well-known advantages in the solution of variable domain problems, but are mainly applied in the case of Dirichlet boundary conditions. This paper examines a way to extend this class of methods to the more difficult case of Neumann boundary conditions.
The Radon-Wigner Transform and Its Application to First-order Optical Systems
2009
The Radon-Wigner transform is presented as a tool for the description of 1st-order optical systems. The input/output relationships for this phase-space representation are obtained and their application in analysis and design tasks is pointed out.
Partial *-Algebras of Operators in a PIP-Space
2009
The family of operators on a pip-space V is endowed with two, possibly different, partial multiplications, where partial means that the multiplication is not defined for any pair A,B of elements of Op(V) but only for certain couples. The two multiplications, to be called strong and weak, give rise to two different structures that coincide in certain situations. In this chapter we will discuss first the structure of Op(V) as partial *-algebra in the sense of [AIT02] and then the possibility of representing an abstract partial *-algebra into Op(V).
Isometries between spaces of multiple Dirichlet series
2019
Abstract In this paper we study spaces of multiple Dirichlet series and their properties. We set the ground of the theory of multiple Dirichlet series and define the spaces H ∞ ( C + k ) , k ∈ N , of convergent and bounded multiple Dirichlet series on C + k . We give a representation for these Banach spaces and prove that they are all isometrically isomorphic, independently of the dimension. The analogous result for A ( C + k ) , k ∈ N , which are the spaces of multiple Dirichlet series that are convergent on C + k and define uniformly continuous functions, is obtained.
Errors Generated by Uncertain Data
2014
In this chapter, we study effects caused by incompletely known data. In practice, the data are never known exactly, therefore the results generated by a mathematical model also have a limited accuracy. Then, the whole subject of error analysis should be treated in a different manner, and accuracy of numerical solutions should be considered within a framework of a more complicated scheme, which includes such notions as maximal and minimal distances to the solution set and its radius.
Theoretical Study of the Electronic Spectrum of trans-Stilbene
1997
The electronic spectrum of trans-stilbene in the energy range up to 6 eV has been studied using multiconfigurational second-order perturbation theory (CASPT2). The study includes a geometry determination of the ground state. In all, 12 singlet and one triplet excited states were studied. The calculated spectrum makes it possible to assign the valence excited singlet states corresponding to the three bands observed in the low-energy region of the one-photon absorption spectrum. The most intense feature of the calculated spectrum corresponds to the 11Ag → 21Bu transition at 4.07 eV. The weakly allowed 11Bu state was found 0.3 eV below 21Bu. Transition to the 31Ag state, computed at 4.95 eV, i…
Computing variations of entropy and redundancy under nonlinear mappings not preserving the signal dimension: quantifying the efficiency of V1 cortex
2021
In computational neuroscience, the Efficient Coding Hypothesis argues that the neural organization comes from the optimization of information-theoretic goals [Barlow Proc.Nat.Phys.Lab.59]. A way to confirm this requires the analysis of the statistical performance of biological systems that have not been statistically optimized [Renart et al. Science10, Malo&Laparra Neur.Comp.10, Foster JOSA18, Gomez-Villa&Malo J.Neurophysiol.19]. However, when analyzing the information-theoretic performance, cortical magnification in the retina-cortex pathway poses a theoretical problem. Cortical magnification stands for the increase the signal dimensionality [Cowey&Rolls Exp. Brain Res.74]. Conventional mo…
L'age d'or de la sémiotique littéraire, et quelques consequences théoriques
2015
Dans cet article, je voudrais comparer trois livres fondamentaux pour l’analyse sémiotique des œuvres littéraires, parus à quelques années de distance l’un de l’autre : S/Z de Roland Barthes (1970a), Maupassant de Algirdas J. Greimas (1976) et Lector in fabula de Umberto Eco (1979). Il s’agit de trois différentes approches à la sémiotique de la littérature, parues dans la même décennie, qui, par conséquent, ont produit trois différents objets de la discipline, en causant, avec un progrès considérable dans la recherche sur la signification, des équivoques théoriques qui sont encore à résoudre.
La Tene human burial and animal deposit at Varennes-sur-Seine (Seine-et-Marne)
2002
An adolescent was buried at the bottom of a large irregular shaped pit The body that had been lain on one side, legs tucked under, was in the centre of a ring of stones and was covered by a deposit of a dog and four horses of which two were foals and two were young adults. A thick layer of sand and a second deposit of three horses and a dog covered this first deposit. The adolescent skull had been broken and perforated which adds to the distinctiveness of this burial. Most of the horses had been skinned and the tendons had been removed. Also the four legs of one of the horses in the top deposit had been removed. With no datable finds the radiocarbon analysis gives a date corresponding to th…
Acoustic detection and classification of river boats
2011
We present a robust algorithm to detect the arrival of a boat of a certain type when other background noises are present. It is done via the analysis of its acoustic signature against an existing database of recorded and processed acoustic signals. We characterize the signals by the distribution of their energies among blocks of wavelet packet coefficients. To derive the acoustic signature of the boat of interest, we use the Best Discriminant Basis method. The decision is made by combining the answers from the Linear Discriminant Analysis (LDA) classifier and from the Classification and Regression Trees (CART) that is also accompanied with an additional unit, called Aisles, that reduces fal…