An improved tumor segmentation algorithm from T2 and FLAIR multimodality MRI brain images by support vector machine and genetic algorithm

This paper puts forth a framework of a medical image analysis system for brain tumor segmentation. Image segmentation helps to segregate objects right from the background, thus proving to be a powerful tool in medical image processing. This paper presents an improved segmentation algorithm rooted in support vector machine (SVM) and genetic algorithm. SVMs are the basis of a machine-learning technique that has been used for segmentation and classification of medical images. The database consists of two weighted images: T2 and FLAIR. The proposed system mainly consists of two stages. The first stage performs pre-processing the MRI image, followed by block division. The second stage includes feature extraction, feature selection, and finally, the SVM-based training and testing. The feature extraction is done by first-order histogram and co-occurrence matrix; GA using wrapper method is used to select optimum subset features. Experimental outcomes for 10 patients with over 250 MRIs are proof of the proficiency of our work. The performance of the proposed system is evaluated in terms of specificity, sensitivity, accuracy; time elapsed and figure of merit. This approach also permits the segmentation of image volumes based on training sets selected on a single slice

Design and Robustness Analysis of a PID Based Sliding Mode Controller for a dc-dc Converter

Abstract: This study deals with the design and analysis of a dc-dc converter operating in continuous conduction mode with Proportional-Integral-Derivative control and PID based Sliding Mode Control (SMC). A small signal model is developed using Switching Flow Graph (SFG) from which the control coefficients for the PID controller is selected. PID based SMC uses a control law which constrains the weighted sum of the voltage error, its derivatives and the integral of the voltage error to zero. The equivalent control technique is used in its design which makes the converter more suitable for fixed frequency operation. Sensitivity of these controllers to supply voltage disturbances and load disturbances is studied and results are presented