Search results for "Projection"
showing 10 items of 378 documents
Algorithms for rational discrete least squares approximation
1975
In this paper an algorithm for the computation of a locally optimal polefree solution to the discrete rational least squares problem under a mild regularity condition is presented. It is based on an adaptation of projection methods [8], [12], [13], [14], [18], [19] to the modified Gaus-Newton method [4], [10]. A special device makes possible the direct handling of the infinitely many linear constraints present in this problem.
Normalizing biproportional methods
2002
International audience; Biproportional methods are used to update matrices: the projection of a matrix Z to give it the column and row sums of another matrix is R Z S, where R and S are diagonal and secure the constraints of the problem (R and S have no signification at all because they are not identified). However, normalizing R or S generates important mathematical difficulties: it amounts to put constraints on Lagrange multipliers, non negativity (and so the existence of the solution) is not guaranteed at equilibrium or along the path to equilibrium.
MODELLI, TESTI, PROCESSI: UNO STUDIO COGNITIVO DELLE METAFORE DELESSICALIZZATE E D’INVENZIONE
2014
La tesi di ricerca è basata sulle metafore delessicalizzate e d’invenzione riscontrate all’interno del romanzo di lingua tedesca «Kassandra» scritto nel 1983 dalla scrittrice Christa Wolf e all’interno del racconto di lingua tedesca «Minotaurus: eine Ballade» scritto nel 1985 Friedrich Dürrenmatt. Si vogliono analizzare i processi cognitivi che stanno alla base della creazione dei due tipi di metafore. Per farlo si è scelto di utilizzare tre teorie della linguistica cognitiva: la teoria della metafora concettuale (Lakoff e Johnson, 1980 e 1999); la teoria dell’integrazione concettuale (Turner e Fauconnier, 2002) e la teoria dell’analogia (Monneret, 2004). L’analisi ci permette di comprender…
Fixed point iterative schemes for variational inequality problems
2018
In a wide class of evolutionary processes, the problem of computing the solutions of an initial value problem is encountered. Here, we consider projected dynamical systems in the sense of \cite{Daniele} and references therein. Precisely, a projected dynamical system is an operator which solves the initial value problem: \begin{equation}\label{PDS}\frac{dx(t)}{dt}= \Pi_{\mathbb{K}}\left(x(t),-F(x(t))\right), \quad x(0)=x_0 \in \mathbb{K}, \, t \in [0,+\infty[,\tag{P}\end{equation} where $\mathbb{K}$ is a convex polyhedral set in $\mathbb{R}^n$, $F: \mathbb{K} \to \mathbb{R}^n$ and $\Pi_{\mathbb{K}}: \mathbb{R} \times \mathbb{K} \to \mathbb{R}^n$ is given as follows $\Pi_{\mathbb{K}}(x,-F(x))…
On the generalization of the Boltzmann equation
1974
Starting from the Liouville equation and making use of projection operator techniques we obtain a compact equation for the rate of change of then-particle momentum distribution function to any order in the density. This equation is exact in the thermodynamic limit. The terms up to second order in the density are studied and expressions are given for the errors committed when one makes the usual hypothesis to derive generalized Boltzmann equations. Finally the Choh-Uhlenbeck operator is obtained under additional assumptions.
Analysis of the XENON100 dark matter search data
2014
The XENON100 experiment, situated in the Laboratori Nazionali del Gran Sasso, aims at the direct detection of dark matter in the form of weakly interacting massive particles (WIMPs), based on their interactions with xenon nuclei in an ultra low background dual-phase time projection chamber. This paper describes the general methods developed for the analysis of the XENON100 data. These methods have been used in the 100.9 and 224.6 live days science runs from which results on spin-independent elastic, spin-dependent elastic and inelastic WIMP-nucleon cross-sections have already been reported.
Light Dark Matter Search with Ionization Signals in XENON1T
2019
We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4 keVee, we observe <1 event/(tonne day keVee), which is more than 1000 times lower than in similar searches with other detectors. Despite observing a higher rate at lower energies, no DM or CEvNS detection may be claimed because we cannot model all of our backgrounds. We thus exclude new regions in the parameter spaces for DM-nucleus scattering for DM masses mχ within 3–6 GeV/c2, DM-electron scattering for mχ>30 MeV/c2, a…
The problem of spatial homogeneity in an LCoS projector
2019
Abstract Video projectors allow interesting applications in vision sciences since they provide a large projection area. We have colorimetrically characterized a LCoS projector using a mathematical model requiring additivity and constancy of the primaries -a sigmoid function in our case. Significant differences in chromaticity in the CIELAB space, but not in lightness, were found between the center and the corners of the screen. The lack of spatial homogeneity led us to estimate the parameters of the model as a function of spatial position, using different strategies. The best result was obtained by interpolating the values of the parameters of the model determined from experimental measurem…
Orthographic and Phonological Neighborhoods in Naming: Not All Neighbors Are Equally Influential in Orthographic Space
1997
Abstract The neighborhood size effect refers to the finding that single word naming is faster for stimuli that are orthographically similar to numerous lexical entries. We explored the nature of this phenomenon in five experiments with French pseudowords and words, and we examined the orthographic and the phonological characteristics of neighbors through quantitative analyses of a word corpus. Experiments 1 and 2 showed that the facilitatory effect of neighborhood size was determined by a subset of neighbors, called phonographic neighbors, which are also phonologically similar to the target letter string. Experiments 3 to 5 aimed at assessing the influence of phonographic neighbors as a fun…
Do Phonological Codes Constrain the Selection of Orthographic Codes in Written Picture Naming?
2001
Sound-to-print consistency of picture labels was manipulated in five experiments to investigate whether phonological codes constrain the selection of orthographic codes in written picture naming. In Experiments 1 and 2, participants wrote down picture names which were inconsistent or consistent in the phono-orthographic mapping defined either at the level of the word unit, i.e., heterographic homophones versus nonhomophones (Experiment 1), or at the sublexical level (Experiment 2). In neither experiment did phonographic consistency affect written latencies. Although more errors were observed for inconsistent than for consistent picture names, the observation of a similar error pattern in an…