Mixed Spectra for Stable Signals from Discrete Observations

Rachid Sabre, University of Burgundy, France https://aircconline.com/sipij/V12N5/12521sipij02.pdf

October 2021 | Cited by 2

Abstract

This paper concerns the continuous-time stable alpha symmetric processes which are inivitable in the modeling of certain signals with indefinitely increasing variance. Particularly the case where the spectral measurement is mixed: sum of a continuous measurement and a discrete measurement. Our goal is to estimate the spectral density of the continuous part by observing the signal in a discrete way. For that, we propose a method which consists in sampling the signal at periodic instants. We use Jackson's polynomial kernel to build a periodogram which we then smooth by two spectral windows taking into account the width of the interval where the spectral density is non-zero. Thus, we bypass the phenomenon of aliasing often encountered in the case of estimation from discrete observations of a continuous time process.

Keywords

Spectral density, stable processes, periodogram, smoothing estimate, aliasing.

Using Distance Measure based Classification in Automatic Extraction of Lungs Cancer Nodules for Computer Aided Diagnosis

Maan Ammar1, Muhammad Shamdeen2, MazenKasedeh2, Kinan Mansour3 and Waad Ammar3 , 1AL Andalus University for Medical Sciences, Syria, 2Damascus University, Syria, 3Al Andalus University Hospital, Syria https://aircconline.com/sipij/V12N3/12321sipij03.pdf

June 2021 | Cited by 2

Abstract

We introduce in this paper a reliable method for automatic extraction of lungs nodules from CT chest images and shed the light on the details of using the Weighted Euclidean Distance (WED) for classifying lungs connected components into nodule and not-nodule. We explain also using Connected Component Labeling (CCL) in an effective and flexible method for extraction of lungs area from chest CT images with a wide variety of shapes and sizes. This lungs extraction method makes use of, as well as CCL, some morphological operations. Our tests have shown that the performance of the introduce method is high. Finally, in order to check whether the method works correctly or not for healthy and patient CT images, we tested the method by some images of healthy persons and demonstrated that the overall performance of the method is satisfactory.

Keywords

Nodules classification, lungs cancer, morphological operators, weighted Euclidean distance, nodules extraction.