Search results for "Filter"
showing 10 items of 1019 documents
Advanced Analysis of Propagation Losses in Rectangular Waveguide Structures Using Perturbation of Boundary Conditions
2011
In this paper, propagation losses effects present in rectangular waveguide structures are rigorously considered. For this purpose, a new formulation based on the perturbation of the boundary conditions on the metallic walls of the waveguides combined with an Integral-Equation (IE) analysis technique is proposed. Following this advanced technique, the drawbacks of the classical power-loss method are overcome and a complex modal propagation constant is computed. To validate this theory, we have successfully compared our results with numerical data of lossy hollow waveguides. Next, a Computed-Aided-Design (CAD) software package based on such a novel modal analysis tool has been used to predict…
MULTI-SCALE ANALYSIS OF LUNG COMPUTED TOMOGRAPHY IMAGES
2007
A computer-aided detection (CAD) system for the identification of lung internal nodules in low-dose multi-detector helical Computed Tomography (CT) images was developed in the framework of the MAGIC-5 project. The three modules of our lung CAD system, a segmentation algorithm for lung internal region identification, a multi-scale dot-enhancement filter for nodule candidate selection and a multi-scale neural technique for false positive finding reduction, are described. The results obtained on a dataset of low-dose and thin-slice CT scans are shown in terms of free response receiver operating characteristic (FROC) curves and discussed.
Finite-Time Hâ Filtering for T-S Fuzzy Discrete-Time Systems with Time-Varying Delay and Norm-Bounded Uncertainties
2015
In this paper, we investigate the filtering problem of discrete-time Takagi–Sugeno (T–S) fuzzy uncertain systems subject to time-varying delays. A reduced-order filter is designed. With the augmentation technique, a filtering error system with delayed states is obtained. In order to deal with time delays in system states, the filtering error system is first transformed into two interconnected subsystems. By using a two-term approximation for the time-varying delay, sufficient delay-dependent conditions of finite-time boundedness and $H_{\infty }$ performance of the filtering error system are derived with the Lyapunov function. Based on these conditions, the filter design methods are propose…
Robust L1 fixed-order filtering for switched LPV systems with parameter-dependent delays
2015
Abstract This paper is concerned with the L1 fixed-order filtering problem for a class of switched linear parameter-varying (LPV) systems in which the system matrices and the time delays are dependent on the real-time measured parameters. The authors׳ attention is concentrated on designing the fixed-order filter that guarantees the filtering error system to be exponentially stable and to satisfy a prescribed L1 disturbance attenuation level with respect to all amplitude-bounded disturbances. Based on the switching logic with the minimum average dwell time (ADT), the delay-dependent L1 performance criterion for the switched LPV systems is first established. As there exists coupling between a…
Fuzzy/Kalman Hierarchical Horizontal Motion Control of Underactuated ROVs.
2010
A new closed loop fuzzy motion control system including on-line Kalman's filter (KF) for the two dimensional motion of underactuated and underwater Remotely Operated Vehicle (ROV) is presented. Since the sway force is unactuated, new continuous and discrete time models are developed using a polar transformation. A new hierarchical control architecture is developed, where the high level fuzzy guidance controller generates the surge speed and the yaw rate needed to achieve the objective of planar motion, while the low level controller gives the thruster surge force and the yaw torque control signals. The Fuzzy controller ensures robustness with respect to uncertainties due to the marine envi…
A Nonlinear Observer for Rotor Flux Estimation of Induction Motor Considering the Estimated Magnetization Characteristic
2017
This paper proposes a nonlinear observer for induction machine drives based on space-vector dynamic model of induction machine, expressed in state form, which presents the peculiarity of taking into consideration the magnetic saturation of the iron core. This observer is particularly suitable in order to obtain high accuracy in rotor flux estimation, in both amplitude and phase position, during working conditions characterized by varying flux, among which the most important are those during electrical losses minimization. A Lyapunov-based convergence analysis is proposed in order to suitably compute the numerical observer gain guaranteeing the convergence of the estimation error. The propos…
Phosphonate degradation by Spirulina strains: cyanobacterial biofilters for the removal of anticorrosive polyphosphonates from wastewater
2011
The ability of Spirulina spp. to metabolize the recalcitrant xenobiotic Dequest 2054(®) [hexamethylenediamine-N,N,N',N'-tetrakis(methylphosphonic acid)], a CaSO(4) inhibitor used for boiler treatment and reverse osmosis desalination, was investigated. The compound served as sole source of phosphorus, but not of nitrogen, for cyanobacterial growth. In vivo utilization was followed by (31)P NMR analysis. The disappearance of the polyphosphonate proceeded only with actively dividing cells, and no release of inorganic phosphate was evident. However, no difference was found between P-starved and P-fed cultures. Maximal utilization reached 1.0 ± 0.2 mmoll(-1), corresponding to 0.56 ± 0.11 mmol g(…
Metabolomic by 1H NMR Spectroscopy Differentiates “Fiano Di Avellino” White Wines Obtained with Different Yeast Strains
2013
We employed (1)H NMR spectroscopy to examine the molecular profile of a white "Fiano di Avellino" wine obtained through fermentation by either a commercial or a selected autochthonous Saccharomyces cerevisiae yeast starter. The latter was isolated from the same grape variety used in the wine-making process in order to strengthen the relationship between wine molecular quality and its geographical origin. (1)H NMR spectra, where water and ethanol signals were suppressed by a presaturated T1-edited NMR pulse sequence, allowed for definition of the metabolic content of the two differently treated wines. Elaboration of NMR spectral data by multivariate statistical analyses showed that the two d…
The effect of salt content on the structure of iota-carrageenan systems: Na-23 DQF NMR and rheological studies
2009
International audience; 23Na NMR spectroscopy has been used to study the effects of Na+ ion concentrations on the structure of 1% (w/w) iota-carrageenan systems, a natural gelling polysaccharide used as a thickener in the food industry. Rheological and 23Na T1 relaxation time measurements revealed that gel formation correlates with decreases in ion mobility over the range of 0-3% (w/w) sodium content. 23Na single-quantum (SQ) and double-quantum-filtered (DQF) NMR experiments performed on these systems provided evidence for a bound sodium ion fraction in a specifically ordered environment. These results have allowed us to propose a model for the carrageenan gelation mechanism in the presence…
An adapted optical flow algorithm for robust quantification of cardiac wall motion from standard cine-MR examinations
2012
International audience; This paper presents a method for local myocardial motion estimation from a conventional steady-state free precession cine-MRI sequence using a modified phase-based optical flow (OF) technique. Initially, the technique was tested on synthetic images to evaluate its robustness with regards to Rician noise and to brightness variations. The method was then applied to cardiac images acquired on 11 healthy subjects. Myocardial velocity is measured in centimeter per second in each studied pixel and visualized as colored vectors superimposed on MRI images. The estimated phase-based OF results were compared with a reference OF method and gave similar results on synthetic imag…