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  • Increasing the intensification of heat transfer in shell-and-tube heat exchangers

    The paper studies the problems of heat transfer intensification in shell-and-tube heat exchangers used in the heat supply of buildings. The solution to this problem is to use the circulation of the coolant flow in a pulsed mode, with different frequency pulsations. Based on experimental studies to determine the efficiency of a shell-and-tube water-to-water heat exchanger, a method has been proposed, in accordance with which it has been proved that the pulsed mode, compared to the stationary one, is the most effective in terms of key indicators, such as the heat transfer coefficient and thermal power.

    Keywords: intensification, heat transfer, heat exchanger, coolant, fluctuations, efficiency, thermal power

  • The structure of the cost of materials in ribbed reinforced concrete floor slabs with a variable section width

    The issues of optimization of ribbed reinforced concrete slabs with prestressing of reinforcement, taking into account geometric, strength and cost indicators, are considered. The study was car-ried out on the basis of an analysis of the sales market for building materials, the basics of rein-forced concrete resistance and the provisions of regulatory documents, design activities in the Russian Federation, as well as the works of domestic and foreign scientists. The research method is structural-analytical analysis taking into account the relationships of the factors under study. Analytical and graphic materials are presented, revealing the regularities between the geometric dimensions and the cost of components. The proposed method for determining the efficiency of a structure, taking into account the cost indicators of materials, indicates the feasibility of its ap-plication in design practice. Recommendations for design are given to ensure that structures of the minimum cost are obtained and that meet the requirements of strength and durability.

    Keywords: reinforced concrete, strength, structure, reinforcement, diameter, price, cost, efficiency, dimen-sions, analysis, element

  • Bionic prosthesis control system based on electromyography

    The work is devoted to some questions of prosthetics of human limbs. A prototype of a prosthesis control system based on electromyography is suggested, which is not inferior to existing analogues, but significantly benefits in its cost.

    Keywords: bionic prosthesis, electromyography, EMG sensor, amplifier

  • The method of chemical modification of epoxy compositions

    The article presents theoretical studies of the effect of various plasticizers on the mechanical properties of epoxy compositions. Based on this, the method of plasticization of the epoxy polymer ED-22 was chosen using the introduction of modified epoxy resin UP-563, which differs from the previously used modified compositions for repairing automotive vehicles in the field the simplicity of the availability of modifications in the field and as providing the widest range of changes in the properties of the epoxy composition for USAGE field. The scientific novelty lies in the justification for the creation of a new repair composition consisting of ED-22 epoxy-diane resin modified by UP-563 laproxil for the repair of hull and capacitive parts of automotive equipment in the field, which has increased vibration resistance. frost resistance and impact resistance.

    Keywords: epoxy composition, epoxy resin, restoration, automotive engineering, body part, chemical modification, oligomer, polymer

  • Research convective processes in a capacitive heat exchanger

    The article presents the results of an experimental research on the effect of the pulsating mode a capacitive heat exchanger with an active pipe part on the convective processes heated fluid. Described dignity capacitive heat exchangers. The research was conducted using a thermal imaging surveys. Compares two modes: stationary and pulsating. The method of experimental data processing, based on the analysis of fluid layers. A regression analysis allows to determine the dependence of the relative distribution of the temperature difference between the layers of fluid in the studied mode. The obtained regression equations were presented in the form of an exponential function and harmonic. The effect of pulsing regime on the process of convection in the upper quarter of the heating zone in a capacitive heat exchanger. The study showed the advantage of the capacitive heat exchanger with an active pipe part is often compared with the classical heat exchanger in part the speed of convective processes in the fluid to be heated.

    Keywords: capacitive heat exchanger with an active pipe part, pulse heating system, convective process

  • Acoustic method monitoring electrochemical processes

    The article describes the research of thermodurability of glass-carbon - one of the most promising carbon materials used in the production of luminophors and semiconductor materials, optical single crystals, etc. The aim of this work was to study the behavior glass-carbon in the course of thermo-cyclic testing. As a method of diagnostics of the birth and development of micro-cracks was used by the reception of signals of acoustic emission. It is shown that at heating in the samples glass-carbon there was a strong movement of dislocations in thermocyclic effects ,recognized in the signals of acoustic emission. As the number of pulses when heated above, than during the cooling of the sample, it is evidence of the accumulation of damages in the structure of the cyclic thermal processing glass-carbon samples. It is established, that the curves of the accumulation of defects at the pulses of acoustic emission, differ on the stage of heating and cooling. Proposed to use the curve of the aggregate accounts of acoustic emission pulses as a possible harbinger of destruction when heated glass-carbon of the product.

    Keywords: acoustic emission, electrodeposition, the activity of the AE, the remote control.

  • Improvement of increment borer construction

    The article suggests improvement of increment borer construction by means of installing a ratchet into its handle. The suggested technical solution will allow increasing the efficiency of work with a borer while taking core of wood.   

    Keywords: Increment borer, preparatory works of forest logging, tree age, ratchet, core.