Cryptanalysis of an embedded systems’ image encryption

Multimedia Tools and Applications - Recently, a new image encryption-scheme for embedded systems based on continuous third-order hyperbolic sine chaotic system, has been proposed. The...     

Validation of chlorophyll-α concentration maps from Aqua MODIS over the Gulf of Gabes (Tunisia): comparison between MedOC3 and OC3M bio-optical algorithms

Few studies have focused on the use of ocean colour remote sensors in the Gulf of Gabes (southeastern Tunisia). This work is the first study to evaluate the ocean colour chlorophyll-a product in this area. Chlorophyll-a concentrations were measured during oceanographic cruises performed off the Gulf of Gabes. These measurements were used to validate satellite data acquired from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite. First, two atmospheric correction procedures (standard and shortwave infrared) were tested to derive the remote-sensing reflectance, and then a comparison between two bio-optical (OC3M and MedOC3) algorithms were realized using the in situ measurements. Both atmospheric correction procedures gave similar results when applied to our study area indicating that most pixels were non-turbid. The comparison between bio-optical algorithms shows that using the regional bio-optical algorithm MedOC3 improves chlorophyll-a estimation in the Gulf of Gabes for the low values of this parameter.     

Kinematic limit analysis modelling by a regularization approach and finite element method

Kinematical approach by limit analysis is one of the fundamental methods used to predict the plastic limit state and it is applied successfully to deal with engineering problems in solid mechanics. The kinematical approach consists of minimizing the plastic dissipation power throughout the body, produced by plasticity, which involves functional with norm integrand. Besides, to derive the stress field within the body, one uses the inverse plastic law that is a subdifferential of the dissipation power. The complexity and possible singularity in the derivatives of functionals become a source of many numerical troubles. To overcome these encountered difficulties, we propose a solving algorithm by using a regularization procedure on the basis of the inf‐convolution operation. Some numerical applications by plane strain or axisymmetric finite element method are presented to illustrate the algorithm. Copyright © 2003 John Wiley & Sons, Ltd.     

Enhanced Configurable DCT Cordic Loeffler Architectures for Optimal Power-PSNR Trade-Off

The Discrete Cosine Transform (DCT) is one of the most widely used techniques of transforms in digital signal processing. It is the main algorithm in image and video coding systems. In this paper, we propose an algorithm which generates enhanced Cordic based Loeffler DCT architectures for angle’s precision degrees ranging from 10^?1 to 10^?7. High level PSNR, area and power estimators have been proposed to make a trade-off between consumption and image quality. An optimal architecture has been retained for its low complexity, low power and high PSNR. The complexity of this architecture is the lowest among the conventional DCT architectures even the BinDCT which is a reference in terms of reduced complexity. The selected architecture has also the closest PSNR to the reference Loeffler-DCT architecture without a substancial loss of power.     

Breaking an image encryption scheme based on Arnold map and Lucas series

Multimedia Tools and Applications - Recently, a novel image encryption based on Arnold scrambling and Lucas series has been proposed in the literature. The scheme design is based on...     

Multi-constraints self-adaptation for reconfigurable multimedia embedded systems

The application of multimedia in embedded systems (ES), such as Virtual reality and 3-D imaging, represents the current trend in ES development. Coupling multimedia with ES has raised new multimedia-related challenges that have been added to the common ES constraints. These challenges deal with the real-time, quality, performance and efficient processing requirements of multimedia applications. The integration of self-adaptation in ES development has been, for many years, a paramount solution to cope with these issues. Although there has been extensive research on the topic of ES self-adaptation, the related works still lack global approaches that better deal with multimedia-related constraints. Coordinating different adaptation mechanisms, monitoring multiple system constraints and supporting multi-application contexts are still underexplored. The aim of the present work is to fill in these gaps by providing a global adaptation approach that offers better adaptation decisions with fair resource sharing among competing multimedia applications. With the above challenges in mind, we propose a multi-constraints combined adaptation approach that targets multimedia ES. It addresses four critical system constraints: maximizing the overall system‘s Quality of Application (QoA) under the real-time constraint, the remaining system energy and the available network bandwidth. It coordinates the adaptation at both application and architecture levels. To test and validate the proposed technique, a videophone system is designed on a Xilinx FPGA development board. It executes two complex multimedia applications. The validation results show the aptitude of the proposed system to successfully reconfigure itself at run-time in response to its constraints.

     

Robust hand gesture recognition system based on a new set of quaternion Tchebichef moment invariants

Pattern Analysis and Applications - Hand gesture recognition is a challenging task due to the complexity of hand movements and to the variety among the same gesture performed by distinct subjects....     

Image recognition using new set of separable three-dimensional discrete orthogonal moment invariants

Multimedia Tools and Applications - In this paper, we propose new sets of 3D separable discrete orthogonal moment invariants, named Racah-Tchebichef-Krawtchouk Moment Invariants (RTKMI),...     

Plastic limit analysis with non linear kinematic strain hardening for metalworking processes applications

Limit analysis approaches are widely used to deal with metalworking processes analysis; however, they are applied only for perfectly plastic materials and recently for isotropic hardening ones excluding any kind of kinematic hardening. In the present work, using Implicit Standard Materials concept, sequential limit analysis approach and the finite element method, our objective consists in extending the limit analysis application for including linear and non linear kinematic strain hardenings. Because this plastic flow rule is non associative, the Implicit Standard Materials concept is adopted as a framework of non standard plasticity modeling. The sequential limit analysis procedure which considers the plastic behavior with non linear kinematic strain hardening as a succession of perfectly plastic behavior with yielding surfaces updated after each sequence of limit analysis and geometry updating is applied. Standard kinematic finite element method together with a regularization approach is used for performing two large compression cases (cold forging) in plane strain and axisymmetric conditions.     

A move coordination method for alternative loads in structural optimization

A decomposition technique for alternative loading conditions in the integrated optimal structural design is developed. The method, called the move coordination, consists of partitioning the large structural optimization problem into a set of smaller coupled subproblems. In each subproblem only one loading condition is considered and the subproblems are solved in a parallel cyclic way. The coupling among the subproblems is accomplished through the introduction of coordinating constraints between each subproblem. These constraints ensure that the final design is the same and feasible for all subproblems. The method developed is illustrated by two examples of member sizing of truss structures using the integrated optimal design formulation and geometric programming. The method presents the advantage of reducing the size of the optimization problem as well as the computer processing time. The method is also suitable for implementation on computers using parallel processing.