Perceptual video hashing based on Tucker decomposition with application to indexing and retrieval of near-identical videos

The perceptual video hash function defines a feature vector that characterizes a video depending on its perceptual contents. This function must be robust to the content preserving manipulations and sensitive to the content changing manipulations. In the literature, the subspace projection techniques such as the reduced rank PARAllel FACtor analysis (PARAFAC), have been successfully applied to extract perceptual hash for the videos. We propose a robust perceptual video hash function based on Tucker decomposition, a multi-linear subspace projection method. We also propose a method to find the optimum number of components in the factor matrices of the Tucker decomposition. The Receiver Operating Characteristics (ROC) curves are used to evaluate the performance of the proposed algorithm compared to the other state-of-the-art projection techniques. The proposed algorithm shows superior performance for most of the image processing attacks. An application for indexing and retrieval of near-identical videos is developed using the proposed algorithm and the performance is evaluated using average recall/precision curves. The experimental results show that the proposed algorithm is suitable for indexing and retrieval of near-identical videos.     

Environmental stress cracking resistance of blow moded poly(ethylene terephthalate) containers

A method is developed for determining the environmental stress cracking resistance (ESCR) of blow molded poly(ethylene terephthalate) (PET) containers. By this method, the internal chamber of a container is presurized in 68.9 kPa (10 psi) increments while the outside of the base is being exposed to an environmental stress cracking (ESC) agent. The base of the container is examined after each 68.9 kPa of pressurization if crazing has occurred. The process is continued until a threshold value of craze initiation pressure (CIP) can be determined. Low CIP for the type of containers tested generally corresponds to a high rate of field failures. The method does not only gage the susceptibility of different types of one-piece PET containers to ESC but also provides helpful information to improve the container designs.     

Wavelet weighted distortion measure for retinal images

The diagnostic features of retinal images undergo changes in the course of processing such as for storage, retrieval and transmission. The conventional mean square error and peak signal to noise ratio have limitations in quantifying these local distortions. In this work, a novel wavelet weighted distortion measure (WWDM) is proposed for accurate quantification of diagnostic information loss. The wavelet analysis of retinal image shows that the significant information of a retinal feature is captured by a few subbands. The new approach is based on assigning a weight to each of the subbands depending on its diagnostic significance. The proposed distortion measure is defined as the sum of wavelet weighted root of the normalized mean square error of subbands expressed in percentage. The experimental results show that WWDM performs better in capturing the distortion in retinal features, whereas for distortion in clinically nonsignificant regions, it gives a low value. The qualitative evaluation using Pearson linear correlation coefficient and Spearman rank order correlation coefficient is performed for different artifacts. The investigation shows better correlation values between WWDM and the subjective scores.     

A robust watermarking scheme against frame blending and projection attacks

Camcorder based video copy attack has become a serious threat to the electronic movie distribution services. Although watermarking is used to authenticate against such camcorder based copy attack, in the camcorder recorded videos, the embedded watermark suffers from several geometric distortions and temporal de-synchronizations. This paper proposes a watermarking scheme which is robust against the distortion due to cam-cordering process. Firstly, a comprehensive literature survey has been done on the watermarking schemes resilient to the cam-cording attack. Based on the existing limitations of the state-of-art literature, a watermarking scheme is devised to embed a watermark which is robust against to frame blending and projection attacks which are the major distortions caused during cam-cording. A comprehensive set of experiments has been carried out to show the applicability of the proposed scheme over the existing literature.     

A strategy for biomimetic hybridization of electrospun fiber mat cross-sections

Concentrated synthetic body fluid (c-SBF) recipes have been used in biomimetic deposition of calcium phosphate (CaP) phases on electrospun polycaprolactone (PCL) fiber mats. However, cross-sections of mats could not be coated entirely when simple soaking methods had been used. In this study, calcium and phosphate sources that are used in typical c-SBF recipes were placed in two compartments which were separated by PCL fiber mats. By varying the concentrations of calcium and phosphate sources in either compartment according to a thermodynamic model, the difference between pH levels of compartments was adjusted. A gradual and homogeneous increase in supersaturation levels was achieved on both sides of the membrane with the onset of diffusion of species through the membrane. The strategy of separation of c-SBF constituents permitted coatings that extended through the cross-section of mats. In addition, types of CaP phases that can be precipitated on opposite sides of the membrane under different conditions were predicted by the same thermodynamic model. It was possible to coat the cross-sections of mats with the targeted phase mixtures by using the developed modeling approach.     

Dominant vibration modes for broadband frequency analysis of multiscale structures with numerous local vibration modes

In this paper, an extension of modal analysis in linear computational structural dynamics is presented to deal with complex structures characterized by the presence of numerous local vibration modes and for which the high modal density leads to high-dimension reduced-order models. These local modes consist of isolated vibrations that are dissociated from the global vibrations of the structure skeleton and that turn out to often be of negligible contribution to the global dynamics. Therefore, an automatic mode sorting procedure is proposed to extract the dominant modes that represent the global dynamics of the skeleton. Next, an alternative filtering methodology based on a modified eigenvalue problem is presented, which allows to build, a priori, a small-dimension reduced-order basis of dominant global modes. The two methods are compared to classic modal analysis using three applications, namely, a heterogeneous plate, a simplified nuclear fuel assembly, and a detailed boiling water reactor fuel assembly.     

Instrumented indentation and scratch testing evaluation of tribological properties of tin-based bearing materials

This paper describes a study of some fundamental tribological behavior of two different tin-based bearing materials using scratch and Martens hardness techniques. The scratch test results obtained from the two different tin-based bearing materials were correlated with a function of scratch hardness and coefficient of friction. It is easily observed that the friction coefficients of WM5 are lower than those of WM2 under all scratch test conditions. Beside this, it is clearly distinguished that both materials give higher friction coefficients at higher normal loads and scratch velocities. Also it is found that scratch hardness values of the WM5 materials are higher than WM2 generally. Moreover, optical microscopy was used to determine the scratch hardness of two different tin-based bearing materials by examining the scratch widths. Scanning electron microscopic observations of two different tin-based bearing materials were performed in order to identify the scratch-deformation mechanisms and trace morphology. Beside scratch tests, Martens hardness tests were carried out to evaluate the indentation of materials by considering both the force and displacement during plastic and elastic deformation. By monitoring the complete cycle of increasing and removal of the test force, hardness values were determined.     

Effects of process parameters on tungsten boride production from WO3 by self propagating high temperature synthesis

In the present study, the production parameters of tungsten boride compounds by self-propagating high-temperature synthesis (SHS) method and following leaching process were investigated. In the SHS stage, the products consisting of tungsten borides, magnesium oxide, magnesium borate, and also minor compounds were obtained by using different initial molar ratios of WO₃, Mg and B₂O₃ as starting materials. In the leaching step, Mg containing byproducts, i.e. MgO and Mg₃B₂O₆, existed in the selected SHS product synthesized at 1:8:2.5 initial molar ratio of WO₃:Mg:B₂O₃ were leached out by using aqueous HCl solution to obtain clean tungsten boride compounds at different experimental parameters which are time, acid concentration and temperature. The acid leaching experiments of the SHS product showed that optimum leaching conditions could be achieved by using 5.8 M HCl at 1/10 S/L ratio and the temperature of 80 °C for 60 min.     

The contribution of wind-hydro pumped storage systems in meeting Turkey's electric energy demand

Renewable energy resources have played an important role to meet increasing energy demand in the world. Among the renewable energy resources, especially, wind energy is of interest due to some advantages, such as being clean, environmental friendly etc. However, the intermittent nature of wind creates several problems to the power system operation and new approaches based on the combined use of wind power and energy storage technologies need to be developed. One of these combined systems is wind-hydro pumped storage systems. In this paper, hydropower and wind energy potential of Turkey are investigated in details. Besides, the importance and the necessity of wind-hydro pumped storage systems for Turkey are comprehensively examined and finally, the contribution of wind-hydro pumped storage systems is emphasized in meeting Turkey's electric energy demand.     

Hyperstage Graphite: Electrochemical Synthesis and Spontaneous Reactive Exfoliation

Covalent modification of the π‐electron basal planes of graphene enables the formation of new materials with enhanced functionality. An electrochemical method is reported for the formation of what is referred to as a Hyperstage‐1 graphite intercalation compound (GIC), which has a very large interlayer spacing d₀₀₁ > 15.3 Å and contains disordered interstitial molecules/ions. This material is highly activated and undergoes spontaneous exfoliation when reacted with diazonium ions to produce soluble graphenes with high functionalization densities of one pendant aromatic ring for every 12 graphene carbons. Critical to achieving high functionalization density is the Hyperstage‐1 GIC state, a weakening of the van der Waals coupling between adjacent graphene layers, and the ability of reactants to diffuse into the disordered intercalate phase between the layers. Graphene functionalization with 3,5‐dinitrophenyl groups provides for exceptional dispersibility (0.24 mg mL^?1) in N,N‐dimethylformamide and for conjugation with amines.