Towards a real-time image/video cryptosystem: problems,analysis and recommendations

Multimedia Systems - With the massive use of images over the Internet, the security of some of them has become critical. One of the most used encryption algorithms is AES. Although this algorithm...     

USAD: undetectable steganographic approach in DCT domain

In this work, we propose a new adaptive chaotic steganographic method based on the Discrete Cosine Transform (DCT) and a reversible mapping function. The mapping function is used to map the secret bits into their corresponding symbols. This mapping technique has to preserve the same dynamics, properties and distribution of the original DCT coefficients. The novelty of our approach is based on the adaptive selection phase of embedding spots. This selection is established through a blindness condition which is applied over each image of the database. The proposed embedding scheme within the middle DCT coefficients shows lower probability of detection and higher flexibility in extraction. We evaluate the detection of our method using the Ensemble Classifiers and a set of frequency and spatial domain feature extractors such as the Spatial domain Rich Model (SRM) features, Chen et al.'s 486-dimensional both inter- and intra-block Markov-based features and Liu's 216-dimensional adaptive steganography-based features.     

Siting of PV power plants on inclined terrains

Most of the studies conducted on solar energy assessment and solar system siting focus on flat terrains that are usually difficult and expensive to acquire in urban areas. This paper investigates the possibility of using inclined terrains for siting photovoltaic (PV) power plants surrounding urban area. Both analytical analysis and simulations are carried out in order to analyse and validate the effectiveness and benefits of the use of inclined land for PV siting. Geographical information system and numerical weather prediction were used to implement the suggested original approach and to select suitable inclined terrains for the PV system installation and to calculate the total generation potential for energy production. Muscat, the capital of Oman, was selected as a reference for the implementation of this approach.     

Study of Structural, Magnetic and Electrical Properties of the Rare-Earth Manganite La0.2235Pr0.2235Nd0.2235Sr0.33MnO3

The perovskite-type La_0.2235Pr_0.2235Nd_0.2235Sr_0.33MnO₃ (LPNSM) ceramic sample was prepared using the solid-state reaction at high temperature. The material was subjected to X-ray diffraction and found to crystallize in rhombohedral structure with space group $\mathrm{R}\bar{3}\mathrm{c}$ . Physical characterization of this compound was carried out using magnetization and dielectric properties. From the magnetic characterization of this compound, the existence of a transition from ferromagnetic to paramagnetic at the Curie temperature T _C=289?K was deduced. This T _C-value is in good agreement with the ones obtained from the Curie?CWeiss law (1/???? vs. T). After characterizing this material, a systematic investigation of dielectric properties as a function of temperature was undertaken. It has been found that the sample shows high dielectric constant and diffuse phase transition (DPT) above room temperature. The scaling behavior of the imaginary part of electric modulus, M?? suggests that the relaxation describes the same mechanism at various temperatures in LPNSM.     

Self-organization of pulse-coupled oscillators with application toclustering

We introduce an efficient synchronization model that organizes a population of integrate-and-fire oscillators into stable and structured groups. Each oscillator fires synchronously with all the others within its group, but the groups themselves fire with a constant phase difference. The structure of the synchronized groups depends on the choice of the coupling function. We show that by defining the interaction between oscillators according to the relative distance between them, our model can be used as a general clustering algorithm. Unlike existing models, our model incorporates techniques from relational and prototype-based clustering methods and results in a clustering algorithm that is simple, efficient, robust, unbiased by the size of the clusters, and that can find an arbitrary number of clusters. In addition to helping the model self-organize into stable groups, the synergy between clustering and synchronization reduces the computational complexity significantly. The resulting clustering algorithm has several advantages over conventional clustering techniques. In particular, it can generate a nested sequence of partitions and it can determine the optimum number of clusters in an efficient manner. Moreover, since our approach does not involve optimizing an objective function, it is not sensitive to initialization and it can incorporate nonmetric similarity measures. We illustrate the performance of our algorithms with several synthetic and real data sets     

Evaluation of mutagenic and antimutagenic activities of oligorutin and oligoesculin

Rutin and esculin have been polymerised by laccase. Five fractions with M(w)ˉ between 2127.42 and 8331.85g/mol for oligorutins, and between 688.12 and 6973g/mol for oligoesculins, were obtained. Fourier transformed infrared analysis showed that oligorutins were formed through C-C, C-O and CO linkages, while oligoesculins were obtained through C-C linkages. Monomers, their oligomers and their metabolites exhibited no mutagenic effect. Oligorutins and oligoesculins were more efficient in reducing the mutagenicity of methyl methanesulphonate, by, respectively, 69% and 64.8% in the presence of Salmonella typhimurium TA104, and 79.7% and 68.9% in the presence of S. typhimurium TA102, than were their monomers. The same oligomers revealed greater significant inhibitory effect of 2-aminoanthracene mutagenicity (respectively 82.4% and 79.3% in the presence of S. typhimurium TA104, and 89.2% and 82.9% in the presence of S. typhimurium TA102), than their monomers. Our results strongly suggest the enhancement of the tested monomer antimutagenicity after polymerisation.     

Fatigue life improvements of the AISI 304 stainless steel ground surfaces by wire brushing

The surface and subsurface integrity of metallic ground components is usually characterized by an induced tensile residual stress, which has a detrimental effect on the fatigue life of these components. In particular, it tends to accelerate the initiation and growth of the fatigue cracks. In this investigation, to deliberately generate compressive residual stresses into the ground surfaces of the AISI 304 stainless steel (SS), wire brushing was applied. It was found that under the experimental conditions selected in this investigation, while the surface roughness was slightly improved by the brushing process, the surface residual stress shifted from a tensile stress (σ_‖=+450 MPa) to a compressive stress (σ_‖=−435 MPa). On the other hand, the work-hardened deformation layer was almost two times deeper after wire brushing. Concerning the fatigue life, an improvement of 26% in terms of endurance limit at 2×10⁶ cycles was realized. Scanning electron microscope (SEM) observations of the fatigue fracture location and size were carried out to explain the fatigue life improvement. It was found that the enhancement of the fatigue strength could be correlated with the distribution and location of the fatigue fracture nucleation sites. Concerning the ground surfaces, it was seen that the fatigue cracks initiated at the bottom of the grinding grooves and were particularly long (150–200 μm). However, the fatigue cracks at the brushed surfaces were shorter (20–40 μm) and appeared to initiate sideways to the plowed material caused by the wire brushing. The results of the wire-brushed surface characterization have shown that significant advantages can be realized regarding surface integrity by the application of this low-cost process compared to shot peening.