Tanmoy Dasgupta

Fractional order sliding mode control based chaos synchronization and secure communication

The present work demonstrates a novel fractional order sliding mode controller for synchronization of fractional order chaotic systems and its use in secure communication. First, the existence of the chaotic behaviour is ensured for the autonomous chaotic system under consideration and then a sliding mode controller is designed in order to make the system follow a designated state trajectory. This idea is then extended towards the making of a chaotic transmitter and a chaotic receiver. It is shown that, when synchronized, this can be used to securely transmit an analogue signal.

Colour image encryption based on cross-coupled chaotic map and fractional order chaotic systems

This paper presents a colour image encryption algorithm based on cross-coupled chaotic map and fractional order chaotic systems. Firstly the algorithm employs the cross-coupled chaotic skew tent map to perform the shuffling operation, and then uses the fractional order versions of Lorenzs system and Chens system to disturb image pixel intensity values. Fractional order extensions of the chaotic systems provides a much larger key-space than their original integer order versions. The encrypted image exhibits uniform histogram and a very high entropy for all the three colour channels. Also, the property of zero correlation is satisfied by the intensity values of adjacent pixels in each channel of the encrypted image. Moreover, the algorithm possesses a key-space which is large enough to resist all possible kinds of statistical attacks. Theoretical analysis and experimental results thus demonstrate that the proposed scheme has an excellent efficiency and satisfactory security attributes. However, solving fractional order differential equations is a computationally heavy process. Some efficient computing techniques are successfully employed to deal with this problem, so that the encryption-decryption process is executed reasonably fast.

Grayscale Image Encryption Based on High-Dimensional Fractional Order Chua’s System

This paper proposes a new image encryption algorithm that makes the use of high dimensional fractional order Chua’s chaotic system. Fractional order extension of the Chua’s system gives a much larger key-space than its original integer order version. The proposed image encryption algorithm uses a simple but excellent technique which is quite fast and the encrypted images are found to have very high entropy. The algorithm is shown to be highly robust and almost invulnerable to statistical attacks. Moreover, the algorithm is designed in such a way that it can be extended by incorporating other chaotic systems as well.

A Bengali Handwritten Vowels Recognition Scheme Based on the Detection of Structural Anatomy of the Characters

The present paper describes the development of a novel scheme for recognising Bengali handwritten vowels using mathematical morphology where the characters are first categorised on the basis of their anatomical features. The scanned images of the characters are passed through a weighted decision tree which is designed to analyse the feature set present in them. Based on the detected features, the algorithms easily recognise the individual characters. The extraction of some features has been carried out by generating the curvature scale spaces for the characters. The treatment is performed on scanned binary images of the handwritten characters to detect anatomical features such as ‘bowl’, ‘lobe’ and ‘arm’. The scheme developed here is very fast and it does not need training samples to work.

Design of a novel adaptive variable structure control law for industrial heat exchanger process representing a class of non minimum process plant

This paper presents the development of a novel adaptive backstepping sliding mode control law for temperature control of an industrial heat exchanger system. Backstepping control law has been utilized during the design of reaching mode of the sliding mode controller to ensure a smoother convergence towards sliding surface. However, in order to mitigate the problems of over-conservative approach of robust design, an adaptive mechanism has also been incorporated to find out the appropriate value of the disturbance bound. The proposed control law is robust against the effects of model uncertainties and can address the issues related to tracking problem of a non-minimum phase nonlinear systems. It has been devised in such a generalized manner that it can be used to address the control problem of any other non-minimum phase nonlinear systems.

An improved content aware image resizing algorithm based on a novel adaptive seam detection technique

An image can be considered to be a combination of both significant (foreground) objects and some less significant (background) objects. Content aware image resizing (CAIR) algorithm uses the different edge detection methods to segregate the useful objects from the background. When applied to an image, CAIR can resize the image to a very different aspect ratio without destroying the aspect ratio of the useful objects in the image. However, this method fails when the useful objects in the image are very closely situated. To take care of this, this paper proposes and develops a modified version of the algorithm. Instead of merely finding the edges, the important objects are detected by drawing contours around them with the help of level set based Chan Vese Image Segmentation algorithm and constant convergence rate Modified Delta Bar Delta learning algorithm. Then Seam Carving algorithm is applied which uses Dynamic Programming. A seam which is a 8 connected curved path from top to bottom (vertical seam) or left to right (horizontal seam) is drawn on the unnoticeable pixels of the lesser significant portions by the process of seam carving which helps to resize the image to a new size. The optimum path of the seam is defined by an image energy function which protects the content of the image. If the seams are continuously removed and inserted then the size of an image can be expanded and contracted respectively in both directions.