Challenges of blended-learning

Creation of the virtual environment as an educational resource to increase motivation and inquisition of the students is a great challenge for Russian educational system. The paper considers some issues of blended-learning. Some elements of blended-learning are analyzed through the ways they are implemented in Tomsk Polytechnic University

Converter Circuit "Voltage-Voltage" Investigation for Power Calibrator

The paper presents possible circuits to construct a voltage-voltage converter for the calibrator of fictitious power. The problems of circuit solutions were experimentally identified, and the ways of their elimination were found. One of the main problems of convectors is to provide small harmonic distortions and additional phase shift. The use of deep negative instantaneous value feedback helps to provide the desired level of nonlinear distortions and to reduce the phase shift. Corrective circuits are used to ensure the stability of the transducer at greater depths of the feedback; the half-period average value or rms value feedback is used to ensure the stability and accuracy of conversion. However, the accuracy of the power calibrator can be upgraded and its work for various types of loads can be ensured by means of application follower circuit with modern electronic components which are also discussed in the paper

Study of thermal effects of silicate-containing hydroxyapatites

The possibility of modifications of hydroxyapatite silicate ions, from the extracellular fluid prototype solution under near-physiological conditions has been studied. Formation of silicon-structured hydroxyapatite with different extent of substitution of phosphate groups in the silicate group has been established through chemical and X-ray diffraction analyses, FTIR spectroscopy and optical microscopy. The results obtained are in agreement and suggest the possibility of substitution of phosphate groups for silicate groups in the hydroxyapatite structure when introducing different sources of silica, tetraethoxysilane and sodium silicate, in the reaction mixture. Growth in the amount of silicon in Si-HA results in the increase in the thermal stability of the samples. The greatest mass loss occurs at temperatures in the range of 25-400 °С that is caused by the removal of the crystallization and adsorption water and volatile impurities. It is shown that the modified apatites are of imperfect structure and crystallize in a nanocrystalline state

Data on granulometric composition of calcium phosphate obtained by dispersion method

The kinetics of calcium phosphate crystallization from model solutions of saliva and liquid phase of dental plaque has been studied by the dispersion method. It was found that the composition of the saliva model system is favorable for the growth of larger crystals. The size of the particles in crystallization varies nonlinearly. As supersaturation grows, the amount of formed particles increases, however, the average rate of crystallite growth decreases

Thermal shock removal of defective glass-enamel coating from cast-iron products

A setup for light beam exposure has been developed. The setup was used to consider the technology of thermal shock destruction of the coating by pulsed-periodic exposure to powerful focused light from the xenon arc lamp DKsShRB-10000. It is shown that this type of exposure can effectively remove the glass-enamel coating from iron products. The optimal mode of setup operation to efficiently remove the defective glass-enamel coating is found: the diameter of the focused light beams is 2.5-3.5 cm; the lamp arc pulse current is 350-450 A; pulse duration is (0.5-1) s and pulse repetition frequency is (0.15-0.5) s-1

Type the title of your paper here Effect of the focused light from the xenon arc lamp on the surface tension of the molten enamel

The effect of exposure to the focused light from the xenon arc lamp on the surface tension of molten enamels was studied with a designed light beam setup as compared to that observed in conventional heating in a resistance furnace. The objects under investigation were enamels No. 261, UES-200 and UES-300. The power density of the light beam was varied in the range of (30-80) W/cm{2}. When exposed to light, the surface tension is shown to be an order of magnitude lower than that obtained in conventional furnace heating

Type the title of your paper here Effect of the focused light from the xenon arc lamp on the surface tension of the molten enamel

The effect of exposure to the focused light from the xenon arc lamp on the surface tension of molten enamels was studied with a designed light beam setup as compared to that observed in conventional heating in a resistance furnace. The objects under investigation were enamels No. 261, UES-200 and UES-300. The power density of the light beam was varied in the range of (30-80) W/cm{2}. When exposed to light, the surface tension is shown to be an order of magnitude lower than that obtained in conventional furnace heating

Features of radiation damage of Ni-Ti alloy under exposure to heavy ions of gaseous elements

The consistent patterns of changes in structural and phase state, hardening and temperature ranges of martensitic transformations in Ni-Ti alloy with the shape memory effect after implantation of heavy ions 16O3+, 40Ar8+ and 84Kr15+ under comparable parameters have been experimentally studied. It is found that under the impact of 84Kr15+ ions, a two-layer surface structure with radiation-hardened second layer is formed, radiation-stimulated phase transformation B19'>B2 occurs in the near-surface layer and out-range area, and the martensitic transformation temperature increases toward higher values after implantation of 40Ar8+ and 84Kr15+ ions