Robust Scene-Based Digital Video Watermarking Scheme Using Level-3 DWT: Approach,Evaluation, and Experimentation

This paper presents a robust digital video-watermarking system for copyright and copy protection. The proposed method applies the combination of discrete wavelet transform (DWT) and scene-change-detector. For better understanding, this approach can be presented in the form of four stages. The first stage is finding the frame where the watermark is to be inserted. The analysis of watermarking using the level-3 decomposition of LL subband withDWTis described in the second stage. Transparency and the robustness have been analyzed under fifteen different attacks in the third stage. Improvement in the robustness and transparency, as compare to watermarking using different levels of LL subband is calculated in terms of the normalized correlation and the structural similarity index in the fourth stage. The experimental result reveal that the proposed method yields the extracted watermark image and watermarked video of good quality and can sustain different image processing, JPEG compression and geometrical attacks. Empirical results prove the improvement in the performance as the decomposition level increases from level-1 to level-3. Comparative analysis with the existing schemes proves the improved robustness, better imperceptibility and the reduced computational time of the proposed scheme.     

Application and extension of the stochastic linearization by Anh and Di Paola

This study deals with the stochastic linearization technique in a new setting. First of all, the usual minimum mean-square difference requirement between the original nonlinear force and its linear counterpart is replaced by the orthogonal condition. Additionally, another recently developed idea of first replacing the nonlinear terms by higher order terms, prior to its ordinary reduction to linear ones, is super-imposed with the above condition. The results are checked on several nonlinear oscillators. In the Atalik and Utku oscillator, instead of 14% error obtained with classical linearization, the error is reduced to about 3%. In the Lutes and Sarkani oscillator the error is reduced from 22.85 to 1.23%, nearly 18-fold. In the latter case the optimal number of “regulation” steps is shown to be 2.     

The effect of pitting corrosion on fatigue life

Fatigue testing of pre‐pitted 2024‐T3 aluminium alloy specimens is performed in laboratory air at 22 °C and 40% RH to characterize the effect of pitting corrosion on fatigue life. Specimens, pre‐corroded in a 0.5 M NaCl solution from 48 to 384 h, have fatigue lives that are reduced by more than one order of magnitude after 384 h pre‐corrosion as compared to those of uncorroded specimens. The reduction in fatigue life is interpreted in terms of the influence of the time of exposure to the corrosive environment or pit size. The crack‐nucleating pit sizes, ranging from 20 to 70 μm, are determined from post‐fracture examinations by scanning electron microscopy. Fatigue lives are estimated using a fracture mechanics approach and are shown to be in good agreement with the actual data. A probabilistic analysis shows that the distribution of fatigue life is strongly correlated to the distribution in nucleating pit size.     

Thermal fatigue of a SiC/Ti-15Mo-2.7Nb-3Al-0.2Si composite

The influence of thermal cycling and isothermal exposures in air on the residual ambient temperature strength of SCS-6/Ti-15Mo-2.7Nb-3Al-0.2Si (weight percent) metal-matrix composites comprised of [0]₄ and [0/90]_s laminates has been determined. A maximum temperature of 815 °C was used in thermal cycling and isothermal exposure. Temperature range, cycle count, maximum/minimum temperature, environment, and hold time at temperature were systematically varied. Postexposure ambient-temperature tension testing, scanning electron and optical microscopy, and fractography were performed on selected specimens to determine the degree of damage. A reduced residual strength was noted in thermal fatigue with increasing cycle count, maximum temperature, and hold time for all specimens tested in air. Isothermal exposures at 815 °C also substantially reduced residual ambient-temperature strength. Considerably less reduction in strength occurred in inert environment than in air. Damage processes included matrix cracking, fiber/matrix interface damage, matrix embrittlement by interstitials, and oxide scale formation at specimen surfaces and, in some cases, at matrix/fiber interfaces. Fiber orientations which allowed rapid ingress of oxygen lead to greater matrix embrittlement and resulted in more pronounced reductions in strength. Formerly with the Materials Directorate, Wright Laboratory, Wright Patterson AFB, Dayton, OH 45433