Fine logarithmic adaptive soft morphological algorithm for synthetic aperture radar image segmentation

, Article IET Image Processing ; Volume 8, Issue 2 , 2014 , Pages 90-102 ; ISSN: 17519659 Koosha, M ; Hajsadeghi, K ; Koosha, M ; Sharif University of Technology

2014

Abstract

Synthetic aperture radar (SAR) appropriate image processing in conjunction with noise reduction is crucial in proper image segmentation. The authors present a new algorithm, logarithmic adaptive soft morphological (LASM) filter, utilising collectivity and flexibility of order-statistic soft morphological filters. This method not only reduces the speckle noise of the single-look SAR imagery considerably, but it significantly enhances the segmentation results. To verify the performance, a simulated SAR image is first created by applying an imagery method to an original noiseless image. The resulting image has characteristics identical to a real SAR image. The LASM method, as well as several...

Frequency Analysis of the Wake of an Oscillating Airfoil

, M.Sc. Thesis Sharif University of Technology Shariloo, Koosha (Author) ; Ebrahimi, Abbas (Supervisor)

Abstract

Understanding the physics of unsteady flow is very important due to various applications. Axial compressors, turbines, helicopter blades, and energy harvesters are the essential applications of this problem. An airfoil under pitching oscillation is one of the common cases in unsteady aerodynamics, and several characteristics of the flow around it have been investigated up to now. The frequency analysis of the wake flow for pitching airfoils has received less attention. In this research, experimental tests have been carried out for symmetric airfoil NACA 0012 under pitching oscillation in low Reynolds flow (6×104) and before the airfoil stall condition. The experiments were carried out in the...

Speckle Noise Reduction Using Adaptive Filters with Application to SAR Images

, M.Sc. Thesis Sharif University of Technology Koosha, Mohaddeseh (Author) ; Hajsadeghi, Khosrow (Supervisor)

Abstract

SAR image noise is a significant problem for SAR image analysis.The inherent noise of SAR images, known as speckle, seriously affects the SAR image interpretation. It also has adverse effects on the classification and segmentation of SAR images. Due to its great significance, the SAR image processing has received considerable attention in recent years and many researchers have developed techniques to reduce the inherent noise accompanying the SAR images. A survey of the literature shows that the wavelet analysis is one of the most common methods used for speckle reduction. While the power of the morphological analysis method has mostly not been recognized, we have utilized this efficient...

Wavelet analysis of the flow field around an oscillating airfoil undergoing pure pitching motion at low Reynolds number

, Article Physics of Fluids ; Volume 35, Issue 6 , 2023 ; 10706631 (ISSN) Ghamkhar, K ; Ebrahimi, A ; Shariloo, K ; Sharif University of Technology

American Institute of Physics Inc 2023

Abstract

This paper investigates the flow field around a NACA (National Advisory Committee for Aeronautics) 0012 airfoil undergoing pure pitching motion using continuous wavelet transform. Wind tunnel experiments were performed with a test-stand that provides a wide range of oscillation frequencies (f = 0-10 Hz). Sinusoidal pure pitching motion was considered with respect to the quarter chord for five reduced frequencies (K = 0.05, 0.1, 0.15, 0.2, and 0.3) at a Reynolds number of Re = 6 × 104. Mean angle of attack and pitch amplitude for all the cases were considered 0° and 6°, respectively. Unsteady surface pressure measurement was conducted, and the lift coefficient was calculated based on the...