Search results for "Oise"
showing 10 items of 1967 documents
Vector anisotropic filter for multispectral image denoising
2015
In this paper, we propose an approach to extend the application of anisotropic Gaussian filtering for multi- spectral image denoising. We study the case of images corrupted with additive Gaussian noise and use sparse matrix transform for noise covariance matrix estimation. Specifically we show that if an image has a low local variability, we can make the assumption that in the noisy image, the local variability originates from the noise variance only. We apply the proposed approach for the denoising of multispectral images corrupted by noise and compare the proposed method with some existing methods. Results demonstrate an improvement in the denoising performance.
The TES-based cryogenic anticoincidence detector for IXO: First results from large area prototypes
2010
The technique which combines high resolution spectroscopy with imaging capability is a powerful tool to extract fundamental information in X-ray Astrophysics and Cosmology. TES (Transition Edge Sensors)-based microcalorimeters match at best the requirements for doing fine spectroscopy and imaging of both bright (high count rate) and faint (poor signal-to-noise ratio) sources. For this reason they are considered among the most promising detectors for the next high energy space missions and are being developed for use on the focal plane of the IXO (International X-ray Observatory) mission. In order to achieve the required signal-to-noise ratio for faint or diffuse sources it is necessary to r…
Temperature effects on the performances of the ATHENA X-IFU thermal filters
2016
The X-Ray Integral Field Unit (X-IFU) detector on-board ATHENA is an array of TES micro-calorimeters that will operate at ~50 mK. In the current investigated design, five thermal filters (TF) will be mounted on the cryostat shields to attenuate IR radiative load and avoid energy resolution degradation due to photon shot noise. Each filter consists of a thin polyimide film (~50 nm thick) coated with aluminum (~30 nm thick). Since the TF operate at different temperatures in the range 0.05-300 K, it is relevant to study how temperature affects their mechanical/optical performances (e.g. near edge absorption fine structures of the atomic elements in the filter material). Such results are crucia…
Thermal modelling of the ATHENA X-IFU filters
2018
Copyright 2018 Society of Photo-Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. The X-IFU instrument of the ATHENA mission requires a set of thermal filters to reduce the photon shot noise onto its cryogenic detector and to protect it from molecular contamination. A set of five filters, operating at different nominal temperatures corresponding to the cryostat shield temperatures, is currently baselined. The knowledge of the actual filter temperature profi…
Performing ‘us’ and ‘other’ : Intersectional analyses of right-wing populist media
2020
Finland and Sweden share the ideal of a Nordic welfare state, with gender equality as a central tenet. In both countries, right-wing populist parties have gained prominence in mainstream politics. Despite similar political agendas at the moment, these parties have different political histories, and different modes of expressing their anti-immigration pleas. In this comparative study, we examine how the distinction between ‘us’ and the ‘other’ is performed intersectionally in terms of gender, social class, ethnicity and ‘race’, and sexuality. For this purpose, we examine empirical material collected from the party newspapers of the Finns Party and the Sweden Democrats, because their content…
E-wave and heart rate responses during anticipation of nonmotor events.
1994
This study concentrated on three main questions: 1) can anticipatory late negative shift (expectancy wave, E-wave) be elicited in nonmotor S1-S2 paradigm, 2) is it sensitive to variation of emotional aspects of the task and 3) is there a connection between heart rate (HR) responses and E-wave. S1 was a letter row that was replaced tachistoscopically by another letter row (S2). The task of the subjects (n = 12) was to detect if the critical aspects of S2 were similar to S1. After their delayed response they received feedback of their performance. The emotional aspects of the task were varied by presenting aversive noise bursts at the end of the feedback period either always, contingently to …
Refugee-background students negotiating academic literacy practices in L2: a dialogical and nexus analytical approach
2022
Tässä artikkelissa tarkastellaan pakolaistaustaisten opiskelijoiden osallistumista akateemisiin tekstikäytänteisiin toisella kielellä. Näillä opiskelijoilla oli myös aiempaa korkeakoulutusta. Ryhmä on jäänyt aiemmissa tutkimuksissa vähälle huomiolle. Tutkimuksen konteksti on uudenlainen korkeakoulutaustaisille maahanmuuttajille tarkoitettu koulutus, jossa yhdistyvät kieli- ja sisältöopinnot. Tutkin, miten kaksi avainosallistujaa ymmärtää ja ottaa haltuun suomenkielisen laskentatoimen kurssin tekstikäytänteitä osana koulutusta. Teoreettisesti ja metodologisesti tutkimus nojaa dialogiseen lähestymistapaan ja neksusanalyysin viitekehykseen. Ensisijainen aineisto koostui haastatteluista ja vide…
High Reynolds number Navier-Stokes solutions and boundary layer separation induced by a rectilinear vortex
2013
Abstract We compute the solutions of Prandtl’s and Navier–Stokes equations for the two dimensional flow induced by a rectilinear vortex interacting with a boundary in the half plane. For this initial datum Prandtl’s equation develops, in a finite time, a separation singularity. We investigate the different stages of unsteady separation for Navier–Stokes solution at different Reynolds numbers Re = 103–105, and we show the presence of a large-scale interaction between the viscous boundary layer and the inviscid outer flow. We also see a subsequent stage, characterized by the presence of a small-scale interaction, which is visible only for moderate-high Re numbers Re = 104–105. We also investi…
COMPARATIVE EVALUATION OF DATA PREPROCESSING SOFTWARE TOOLS TO INCREASE EFFICIENCY AND ACCURACY IN DIFFUSION KURTOSIS IMAGING
2016
Introduction: Diffusion tensor imaging (DTI) is the most commonly used technique to extract microstructural features from a set of diffusionweighted images. In addition to the metrics obtained with DTI, diffusion kurtosis imaging (DKI) can provide non-Gaussian diffusion measures by means of the kurtosis tensor. DKI has shown to be more sensitive to tissue microstructural changes in both normal and pathological neural tissue. In a clinical setting, however, these benefits are often nullified by numerous acquisition artifacts. The aim of this study was compare two preprocessing software for DTI apply to DKI. Also, the major preprocessing, processing and post-processing procedures applied to D…
Anomalous transport effects on switching currents of graphene-based Josephson junctions
2017
We explore the effect of noise on the ballistic graphene-based small Josephson junctions in the framework of the resistively and capacitively shunted model. We use the non-sinusoidal current-phase relation specific for graphene layers partially covered by superconducting electrodes. The noise induced escapes from the metastable states, when the external bias current is ramped, give the switching current distribution, i.e. the probability distribution of the passages to finite voltage from the superconducting state as a function of the bias current, that is the information more promptly available in the experiments. We consider a noise source that is a mixture of two different types of proce…