Oxidation of molten Al-Mg alloy in air,air-SO2, and air-H2S atmospheres

Rates of oxidation of 8 g samples of molten Al-Mg alloys in air, air-SO₂, and air-H₂S atmospheres were determined at 750°C by gravimetry. Weight gains in air containing 10 or more volume percent SO₂ averaged 0.2 % in up to 100 hr, whereas samples heated in air alone gained over 5% weight in 20 hr and 10% in 70 hr. Heating for only 1 hr in SO₂ concentrations of 10% or greater prevented extensive oxidation during additional heating in air alone. H₂S was more effective than SO₂ heating for as little as 1/2hr in 0.25 vol. % H₂S prevented extensive oxidation during subsequent heating for at least 90 hr in air alone. The inhibiting effect of either SO₂ or H₂S probably involves oxidation to SO₃. This reacts with portions of the initial protective amorphous MgO film to form MgSO₄, which has a high volume quotient and maintains protection as nonprotective crystalline MgO forms at the end of an induction period.     

Intermetallic phase formation in directionally solidified Al−Si−Fe alloy

The present study has been undertaken to better understand the solidification behavior of Al−Si−Fe alloys containing 7wt.% Si and 0.9wt.% Fe, with particular regard to the formation of phase during controlled solidification and influence of growth rates on intermetallic phase selection. The alloys studied were Al-7Si-0.9Fe alloys, which were produced by a modified Bridgman solidification arrangement. These alloys were solidified unidirectionally with different growth rates (1–30mm/min). The solidified microstructure of these alloys consists of the growth of primary aluminum and multiple second phase reactions.     

The effects of silicon on the properties of tantalum

The microalloying of tantalum with silicon has been effectively used on a commercial scale. However, data on effects of microalloying on processibility, microstructure and mechanical properties are not readily available. To develop some data, tantalum powder with various levels of silicon (0–50 ppm) was processed under identical conditions. Sheet samples were then annealed at different temperatures and evaluated via microstructural, chemical and mechanical tests. The recrystallization temperature was found to increase with silicon content, most probably as a result of the presence of an intermetallic (Ta₃Si) phase. The mechanical properties of unrecrystallized tantalum are, as expected, significantly different from those of recrystallized tantalum.     

A novel Rotational Symmetry Dynamic Texture (RSDT) based sub space construction and SCD (Similar-Congruent-Dissimilar) based scoring model for background subtraction in real time videos

Multimedia Tools and Applications - Background Subtraction (BS) plays an important role in video surveillance system because it provides a focus of attention for moving object detection. But there...     

Dynamic model of proximity of positions of social network users

A mathematical model is proposed for the proximity dynamics of political positions of interacting individuals which form a closed group. The model is described as a system of ordinary differential equations. The results of numerical experiments for the system are presented and a number of substantial conclusions are formulated. It is shown that in the case of two individuals the system has an asymptotically stable zero steady state. In the case of two individuals and two themes we get an infinite number of stationary states, all except the zero state being unstable.     

Fast rank algorithms based on multiscale histograms and lazy calculations

Rank algorithms allow effective solutions for image smoothing and impulse noise suppression, but most of them are computationally complex. On the base of multiscale histograms, we propose algorithms for fast computations of EV and KNV neighborhood average, sliding equalization and search for an arbitrary element in a rank series (median filtering is a particular case of this algorithm). An approach using lazy calculations for fast updating of multiscale histograms is proposed. Using the developed algorithms, we have achieved a processing speed for EV and KNV neighborhood average algorithms that is close to the fastest known median filtering algorithm.     

Efficient wavelet-based ECG processing for single-lead FHR extraction

This paper describes a novel model for fetal heart rate (FHR) monitoring from single-lead mother?s abdomen ECG (AECG) measurements. This novel method is divided in two stages: the first step consists on a one-step wavelet-based preprocessing for simultaneous baseline and high-frequency noise suppression, while the second stage efficiently detects fetal QRS complexes allowing FHR monitoring. The presented structure has been simplified as much as possible, in order to reduce computational cost and thus enable possible custom hardware implementations. Moreover, the proposed scheme and its fixed-point modeling have been tested using real abdominal ECG signals, which allow the validation of the presented approach and provide high accuracy.