Search results for "wave"
showing 10 items of 6009 documents
<title>Human cell texture analysis with quincunx spline wavelet transform</title>
1999
Wavelet transforms are efficient tools for texture analysis and classification. Separable techniques are classically used but present several drawbacks. First, diagonal coefficients contain poor information. Second, the other coefficients contain useful information only if the texture is oriented in the vertical and horizontal directions. So an approach of texture analysis by non-separable transform is proposed. An improved interscale resolution is allowed by the quincunx scheme and this analysis leads to only one detail image where no particular orientation is favored. New orthogonal isotropic filters for the decomposition are constructed by applying McClellan transform on one dimension B-…
<title>Multiresolution description of range images through 2D quincunx wavelet analysis</title>
1999
In this paper, we present a method for performing a multi- scale analysis on range images by using the wavelet transform, that is capable of revealing multi-resolution information. An accurate non-contact optical system based upon laser triangulation is used to determine the depth information of the object being scanned. The resulting range image is treated as a gray-level image by using a multi- resolution approach based on the generalization of the cascade algorithm using the quincunx wavelet transform. The quincunx wavelet assures very fine analysis. This method allows reconstruction of non-subsampled images that correspond to decompositions previously done at chosen scales. Multi-resolu…
A statistical model for magnitudes and angles of wavelet frame coefficients and its application to texture retrieval
2014
Abstract This paper presents a texture descriptor based on wavelet frame transforms. At each position in the image, and for each resolution level, we consider both vertical and horizontal wavelet detail coefficients as the components of a bivariate random vector. The magnitudes and angles of these vectors are computed. At each level the empirical histogram of magnitudes is modeled by a Generalized Gamma distribution, and the empirical histogram of angles is modeled by a different version of the von Mises distribution that accounts for histograms with 2 modes. Each texture is characterized by few parameters. A new distance is presented (based on the Kullback–Leibler divergence) that allows g…
Collision Avoidance Trajectory for an Ekranoplan.
2009
The risk of collision is one of the crucial aspects for the applications of Ekranoplans in civil transportation. In fact, the extremely low flight altitude of these aircraft increases dramatically the chances of interference between their flight path and the multitude of obstacles populating the surrounding area. In this work we consider the optimal collision avoidance problem between a cruising Ekranoplan and a steady obstacle located on its flight path. First we solve the optimal control problem imposing that the collision avoidance maneuver lies on the longitudinal plane identified by the initial cruising conditions. In the second part of this work we state the three-dimensional version …
Extrasystolie während extrakorporaler biliärer Stoßwellenlithotripsie: Inzidenz und klinische Bedeutung*
2008
Incidence and clinical significance of cardiac side effects of extracorporeal shock-wave lithotripsy (ESWL) were prospectively analysed for 85 patients (26 men, 59 women; mean age 44 [17-81] years) with cholecystolithiasis (n = 70) or choledocholithiasis (n = 15). 24-hour ECG monitoring was undertaken on the day of treatment. Additionally, during ESWL cardiac rhythm and blood pressure were monitored. ESWL was performed with an electromagnetic lithotriptor under light anaesthesia with intravenous diazepam (10 mg) and pethidine (75-100 mg). There were no superventricular premature systoles in any of the patients during treatment. In 15 patients with occasional ventricular premature systoles (…
Second Language Interference during First Language Processing by Arabic-English Bilinguals.
2017
The research investigated whether a bilinguals’ second language (L2) is activated during a task involving only the first language (L1). We tested the hypothesis that the amount of L2 interference can vary across settings, with less interference occurring in testing locations where L2 is rarely used. In Experiment 1, we compared language processing for 50 Arabic–English bilinguals tested in Saudi Arabia and 49 Arabic–English tested in the United States. In the task, participants viewed a picture and judged whether a phoneme presented over headphones was part of the L1 picture name. The results showed no effect of testing location on processing. For both groups of bilinguals, we observed L2 i…
Low-Cost Sensor Based on SDR Platforms for TETRA Signals Monitoring
2021
The paper presents the design and implementation of an electromagnetic field monitoring sensor for the measurement of the Terrestrial Truncked Radio (TETRA) signals using low-cost software defined radio (SDR) platforms. The sensor includes: an SDR platform, a Global Positioning System (GPS) module and a hardware control module. Several SDR platforms having different resolutions of the analog–digital converters were tested in the first phase. The control module was implemented in two variants: a fixed one, using a laptop, and a mobile one, using a Raspberry Pi. The tests demonstrate the following achieved performances: instantaneous acquisition band of 5.12 MHz
Aortic Stiffness in HIV Infection with and without Antiretroviral Therapy. A Meta-analysis of Observational Studies
2020
Background: The risk of Cardiovascular (CV) events is higher in HIV-infected patients (HIV+) compared to HIV-uninfected persons (HIV−). Large artery stiffness, a well-documented predictor of adverse CV prognosis, may mediate this enhanced risk. It is usually assessed by measuring aortic Pulse Wave Velocity (aPWV). Studies examining arterial stiffness in HIV+ yielded inconsistent results. We performed a meta-analysis with the aim to evaluate the association of HIV infection and its therapy [Antiretroviral Therapy (ART)] with aPWV. Design and Method: The Standardized Mean Difference (SMD) and corresponding 95% confidence intervals were calculated for aPWV in different comparison groups. Stati…
Observatory science with eXTP
2019
Disponible preprint en: arXiv:1812.04023v1 [astro-ph.HE] [v1] Mon, 10 Dec 2018 19:00:52 UTC (4,376 KB)
Measurement of three-dimensional mirror parameters by polarization imaging applied to catadioptric camera calibration
2008
International audience; We present a new efficient method for calibration of cata- dioptric sensors. The method is based on an accurate measurement of the three-dimensional parameters of the mirror through polariza- tion imaging. While inserting a rotating polarizer between the cam- era and the mirror, the system is automatically calibrated without any calibration patterns. Moreover, this method permits most of the constraints related to the calibration of catadioptric systems to be relaxed. We show that, contrary to our system, the traditional meth- ods of calibration are very sensitive to misalignment of the camera axis and the symmetry axis of the mirror. From the measurement of three-di…