Search results for "FREQUENCY"

On Bifurcation Analysis of Implicitly Given Functionals in the Theory of Elastic Stability

2015

In this paper, we analyze the stability and bifurcation of elastic systems using a general scheme developed for problems with implicitly given functionals. An asymptotic property for the behaviour of the natural frequency curves in the small vicinity of each bifurcation point is obtained for the considered class of systems. Two examples are given. First is the stability analysis of an axially moving elastic panel, with no external applied tension, performing transverse vibrations. The second is the free vibration problem of a stationary compressed panel. The approach is applicable to a class of problems in mechanics, for example in elasticity, aeroelasticity and axially moving materials (su…

Nonlinear vibrations of elastic beams with external general visco-elastic devices

2011

Vibration damping for slender beams is achieved by applying devices at external points. The latter consist of general single visco-elastic springpot elements. An approximate nonlinear boundary value problem is found in frequency domain that holds for moderately large vibrations or for linear beams with external nonlinear devices, both in the vicinity of primary resonances. The interaction force of a so-called springpot element is expressed as a sum of two separate forces: the first develops due to the external loading function at the device location, and the second contribution arises due to an imposed time-harmonic support excitation with no other external forces acting on the structure. F…

Noise contribution to resonance phenomena and information propagation in non linear electronic networks

2015

This manuscript presents research aiming to show possible positive effects of deterministic and stochastic perturbations on the responses of different nonlinear systems. To that end, both numerical and experimental studies were carried out on two kinds of structures : an elementary electronic FitzHugh-Nagumo oscillator and an electrical line developed by resistively coupling 45 elementary cells. In the first section, the elementary cell characterization was undertaken in a deterministic regime. In the presence of a bichromatic stimulus, it is shown that when the low frequency component is subthreshold, its detection can be maximized for an optimal magnitude of the second component thanks to…

Hybrid VLC/WiFi Architectures with Priority Feedback Channels

2022

In this paper, we consider integrating Visible Light Communication (VLC) and WiFi technologies in an ultra-dense (massive) Internet of Things scenario, where WiFi links are used for complementing VLC links and vice-versa. Indeed, in case of mobility and/or bidirectional communications, limited coverage areas and self-generated interference can be an issue. We consider hybrid VLC/WiFi nodes where the VLC link is used for the majority of (data) traffic and the WiFi link is employed as a feedback channel (e.g. transmitting TCP ACKs). In presence of intense WiFi traffic, the WiFi network may be congested and thus, to fully exploit the VLC bandwidth, we discuss possible priority mechanisms to fu…

Visual performance with multifocal intraocular lenses

2004

Abstract Objective To evaluate distance and near visual performance under bright (photopic) and dim (mesopic) conditions in patients who had undergone uncomplicated cataract extraction with multifocal or monofocal intraocular lens (IOL) implantation. Design Prospective, nonrandomized, masked, comparative, observational case series. Participants Thirty-two eyes of 32 patients after zonal-progressive multifocal IOL implantation (Allergan Medical Optics Array SA-40N) and 32 eyes of 32 age-matched patients after monofocal IOL implantation (Allergan Medical Optics SI-40NB). Intervention All eyes underwent phacoemulsification and IOL implantation. Main outcome measures At 18 months after surgery,…

Evaluating the Effect of Stimuli Color and Frequency on SSVEP

2020

Brain&ndash

2016

Processing natural scenes requires the visual system to integrate local features into global object descriptions. To achieve coherent representations, the human brain uses statistical dependencies to guide weighting of local feature conjunctions. Pairwise interactions among feature detectors in early visual areas may form the early substrate of these local feature bindings. To investigate local interaction structures in visual cortex, we combined psychophysical experiments with computational modeling and natural scene analysis. We first measured contrast thresholds for 2x2 grating patch arrangements (plaids), which differed in spatial frequency composition (low, high or mixed), number of gr…

When WORDS with Higher-frequency Neighbours Become Words with No Higher-frequency Neighbour (Or How to Undress the Neighbourhood Frequency Effect)

2000

Abstract “SATOR AREPO TENET OPERA ROTAS” (The ploughman, with his plough, manages the work) The influence of lexical similarity on word recognition has been discussed not only because of its theoretical impact but also because it is difficult to replicate. Among the multiplicity of the causes of this inconsistency one reason can be that different words were used in comparing words with higher-frequency neighbours (HFN) and words without HFN. In this experiment we chose French words for which the neighbourhood changes when they are written in UPPER case or in lower case. For example ‘DEFI’ has one HFN (‘DEMI’) but when it is displayed in lower case ‘defi’ has no HFN because ‘demi’ has no acc…

LA NOTION DE COLLOCATION FONDAMENTALE UNE ETUDE DE CORPUS

2016

Dans cette étude les « collocations fondamentales » sont envisagées comme des unités polylexicales significatives (unies par des liens collocationnels) fréquentes (dans l'usage) ou non fréquentes (lorsqu'elles sont pertinentes pour la communication) qui représentent pour les locuteurs natifs les contextes les plus essentiels d'un mot donné. Nous avons extrait du corpus frWaC (Baroni et al. 2010) environ 20 000 associations à partir de dix mots pivots issus du Dictionnaire Fondamental de Gougenheim (1971) ; puis, au moyen de la fréquence et de mesures d'association, nous avons sélectionné un échantillon d'environ 400 associations candidates au statut de collocations fondamentales et demandé …

BuscaPalabras: a program for deriving orthographic and phonological neighborhood statistics and other psycholinguistic indices in Spanish.

2005

This article describes a Windows program that enables users to obtain a broad range of statistics concerning the properties of word and nonword stimuli in Spanish, including word frequency, syllable frequency, bigram and biphone frequency, orthographic similarity, orthographic and phonological structure, concreteness, familiarity, imageability, valence, arousal, and age-of-acquisition measures. It is designed for use by researchers in psycholinguistics, particularly those concerned with recognition of isolated words. The program computes measures of orthographic similarity online, with respect to either a default vocabulary of 31,491 Spanish words or a vocabulary specified by the user. In a…