Conditions for the formation and the structure of a metastable cerium modification

Mathematical simulation of heat transfer processes and X-ray diffraction analysis were used to show that, upon the quenching of cerium from the melt at rates of greater than 3.5 × 10⁵ K/s, a metastable μ′-Ce modification with a seven-layer hexagonal structure is formed. The formation of μ′-Ce is explained by the accumulation and ordering of stacking faults in the fcc lattice of the γ phase leading the process of crystallization upon rapid cooling from the melt.     

Results of Combined Cleaning of the Internal Heating Surfaces of High-Pressure Heaters

The technology, flow diagram, and results of combined cleaning of deposits from the internal heating surfaces (tubes) of high-pressure heaters are describe     

Multilayer Composites Based on PTFE Films and Fiberglass

Fibre Chemistry - The article is devoted to the development of two-layer composites with a fluoroplastic matrix and fiberglass reinforcing elements. The fluoroplastic matrix acts as a protective...     

An improved algorithm of median flow for visual object tracking and its implementation on ARM platform

An improved algorithm of median flow used for visual object tracking is described. The improvement consists in adaptive selection of aperture window size and number of pyramid levels at optical flow estimation. It can increase the tracking efficiency as compared to the basic algorithm, especially when dealing with small and low-contrast objects. The proposed version of the algorithm has been implemented using OpenCV library and tested on OMAP 35x EVM and BeagleBoard-xM based on Texas Instruments OMAP3530 and DM3730 processors, respectively. Analysis of improved median flow was performed over actual video sequences. The results obtained show versatility and computational robustness of the algorithm, which makes it promising for embedded application based on ARM processors.     

Study of Nano-Porous Silicon with Low Thermal Conductivity as Thermal Insulating Material

Recently discovered phenomenon of extremely low thermal conductivity of nano-porous silicon (nano-PS) is discussed in detail. A theoretical model describing specific mechanisms of heat transport in as-prepared and oxidized nano-PS layers is described. The theoretical estimations are in a good agreement with experimental data obtained earlier. The low thermal conductivity values allow to use this promising material as thermal insulator in microsensors and microsystems. To ensure an efficient thermal isolation, a nano-PS layer has to be as thick as possible and mechanically stable. We describe here the procedures to form thick (up to 200 m) and stable nano-PS layers. Distribution of Si oxidized fraction along the layer thickness after thermal oxidation in dry O₂ atmosphere at 300°C during 1 h is studied.     

Electrical Conductivity of Film Composites Based on Polyvinyledene Fluoride with Carbon Nanotubes

The results of a study of film composites based on polyvinylidene fluoride with carbon nanotubes (CNTs) by dielectric relaxation spectroscopy are presented. For composite samples containing more than 0.5 wt % of nanotubes, nonlinear current–voltage characteristics are obtained. The concentration dependences of the electrical conductivity of the composites are examined and the percolation threshold for the samples under study is determined. It is shown that an insignificant increase in the electrical conductivity of the composites is observed even upon filling with 0.2 wt % of CNTs, whereas the electrical conductivity becomes three orders of magnitude higher upon the introduction of 1 wt% of CNTs and is seven orders of magnitude higher at more than 3 wt %, compared with the unfilled polymer. This confirms that CNTs are promising for the development of electrically conducting composites and film materials on the basis of polyvinylidene fluoride.     

Hydroconversion of rosin acids in the presence of Pt-containing Al–HMS mesoporous aluminosilicate

The hydroconversion of a mixture of rosin acids over a Pt-containing mesoporous aluminosilicate catalyst has been studied. It has been shown that in a temperature range of 300–350°C at pressures of 30–50 atm and a feedstock/catalyst weight ratio of 20/1, rosin acids undergo complete decarboxylation to form naphthenic and naphthene-aromatic hydrocarbons. Under optimum process conditions, the yield of diesel fuel hydrocarbons is more than 85%. The resulting fraction can be used as a fuel component.