Studying the method of adaptive prediction of forest fire evolution on the basis of recurrent neural networks

A software system is presented for implementation of a fire model on the basis of a recurrent neural network, which ensures real-time simulation of fire evolution. The quality of traditional learning and learning based on the Kalman filter in experiments performed with the neural network is compared. It is demonstrated that the fire overcomes obstacles in the form of regions consisting of incombustible materials owing to the global character of connections of the neural network simulating the fire.     

Effect of heat treatment on corrosion of laser-textured aluminum alloy surfaces

The kinetics of electrochemical corrosion of aluminum alloy (AlMg6) surfaces with different wettability was analyzed. The surfaces were processed by three different methods, in particular, polishing, laser texturing, the combination of laser texturing and low-temperature heating. After laser processing, the dimple-like texture was formed on the surface, and the wettability significantly enhanced. Low-temperature heating of laser-textured AlMg6 alloy surfaces led to the wettability inversion from strongly hydrophilicity to superhydrophobicity. Microscopic and profilometric methods were used to estimate the surface degradation due to corrosion when aggressive solution droplets (a mixture of NaCl and hydrogen peroxide aqueous solutions) evaporated. The potentiodynamic polarization measurements of AlMg6 alloy surfaces were conducted. The typical modes of corrosion and evaporation of aggressive solution droplets were detected. The kinetics of corrosion was estimated by the behavior of the corrosion area evolution. In addition, when immersing laser-textured sample with strongly hydrophilic properties into aggressive solution, the higher corrosion rate was found in the liquid meniscus region (aggressive mixture / alloy / air interface) compared to the textured site immersed in the mixture. This was explained by convection increasing the rate of reaction products removal and promoting a stronger deviation from the equilibrium state in the aggressive mixture. Experimental results of the potentiodynamic polarization measurements revealed that laser-textured samples exhibit enhanced corrosion protective properties compared to polished samples.

Graphical abstract

     

Characteristics of excess phase in cast high-manganese steel

The formation of the excess phase in high-manganese steel is considered over a wide range of cooling rates. This phase, which consists of a phosphide eutectic and secondary carbides, may be deposited both along the grain boundaries and within the grains. At low cooling rates, the phosphide eutectic is mainly formed, with a small quantity of secondary carbides. In addition, excess phase with mixed morphology is encountered. It consists of the eutectic and secondary carbide, with a coherent boundary between them. With increase in the cooling rate, the excess phase consists primarily of secondary carbides; its size is reduced. The influence of the cooling rate on the chemical composition of the excess phase is also of interest. Increase in cooling rate is found to reduce the manganese content in the secondary carbides deposited. The ratio between iron and manganese in the phosphide eutectic does not depend on the cooling rate and is practically constant.     

Smooth regulation of the exciting current in tractional electric motors

Pulsed regulation of the exciting current in dc tractional motors is considered. This method is superior in numerous respects to classical stepwise rheostat regulation. Pulsation and control characteristics of the pulsed regulator are presented.     

Chloride vapor-phase epitaxy of gallium nitride on silicon: Effect of a silicon carbide interlayer

A new approach is described, according to which the use of a thin silicon carbide (SiC) interlayer ensures the suppression of cracking and the simultaneous release of elastic strain in gallium nitride (GaN) epilayers grown by hydride-chloride vapor-phase epitaxy (HVPE) on 1.5-inch Si(111) substrates. Using this method, 20-μm-thick GaN epilayers have been grown by HVPE on Si substrates with AlN (300 nm) and SiC (100 nm) interlayers. A high quality of the obtained GaN epilayers is confirmed by the photoluminescence spectra, where an exciton band with hv_max = 3.45 eV and a half-width (FWHM) of 68 meV is observed at 77 K, as well as by the X-ray rocking curves exhibiting GaN(0002) reflections with a half-width of ω_? = 600 arc sec.