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Головна
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Публікації
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Статті
Combined experimental and numerical tools are developed and used to define more exactly the growth kinetic relations for (211) crystallographic orientation of Bi4Ge3O12 (BGO) crystal growth—namely, the dependence of crystal growth rate V on supercooling, T of the melt/crystal interface. A new apparatus for in situ measurements of the time dependence of the supercooling, T(t), was used, and a new, two-dimensional numerical model was applied to analyze the effect of temperature boundary conditions and faceting phenomena on the character of the observed V(T) dependence. The measurements of the T(t) dependence show that there is a large enough undercooling and a novel effect of the appearance of the local maximum on T(t) dependence at the finish of crystallization. Results on V(T) dependence show that, for the variant of the crystal growth technique used (melt cooling during axial heating process method [AHP]), the type of the V(T) dependence does not depend on boundary conditions. The new investigations illustrate the superlinear behavior for V(T) dependence for (211) BGO crystallographic orientation and show that previous data on sublinear behavior of V(T) dependence for this crystallographic orientation of BGO have not been justified.
На базі методу граничних елементів розроблено числову методику для розв’язання тривимірних стаціонарних нелінійних задач теплопровідності. Створено відповідне програмне забезпечення та виконано його тестування. Проведено числовий аналіз тривимірного теплового стану алюмінієвого електролізера.
A comprehensive efficiency analysis of the energy consumption is carried out for two types of aluminum electrolyzers using graphitized bottom blocks available from the Ukrainian Graphite JSC. The use of bottom blocks high in graphite (50 and 70%) leads to economic consumption of electric power, increased output, and extended service life of the electrolyzers.
Combined experimental and numerical tools are used to analyze the effect of convective and radiative heat transport, faceting phenomena, and the optical thickness of the Bi4Ge3O12 (BGO) crystal on the measurement and calculation of melt/crystal interface kinetics during the axial heat flux close to the phase interface growth of BGO single crystals. Results show that, in the general case, accurate determination of growth kinetic relations requires the application of models which account for all of the above phenomena (radiative and convective heat transport, faceting phenomena, etc.). Failure to take these into account may result not only in quantitative errors, but also even in qualitatively wrong determination of interfacial kinetic mechanisms.
На базі прямого методу граничних елементів розроблено методику числового розв’язання задачі статичної термопружності для сполучених ізотропних тіл. Розроблено універсальне програмне забезпечення для розв’язання двовимірних задач статичної термопружності в сполучених тілах складної форми при різних комбінаціях граничних умов. Проведено тестування програмного забезпечення і виконані розрахунки термопружного стану окремої подової секції, подини і бортової футеровки катодного вузла алюмінієвого електролізеру.
Розглянуто методики числового розв’язання прямим методом граничних елементів ізотропних лінійних та нелінійних і ортотропних лінійних стаціонарних вісесиметричних задач теплопровідності за різних граничних умов. Розроблено відповідні програми розрахунку температурних полів, проведено їх тестування та виконано модельні розрахунки.
Pervaporational nonporous membranes are obtained on the basis of synthetic rubber. The possibility of using the method of evaporation through the obtained membrane is considered for treatment of sewage resulting from styrene, polysterene, polycarbonate, and polysulfone production.
Designs have been developed for two commercial modular membrane units with effective membrane-surface areas of 20 and 100 m s, which can be used to separate azeotropic and thermally unstable mixtures, concentrate solutions and recycle valuable organic substances in the production cycle.
Yet another promising area of application for pervaporation - separation of solid substances from organic solvents (for example, those used in the electronics industry) and crystalline solid substances from essential oils used in the foodstuff and pharmaceutical industry (for example, menthol from peppermint oil) - should be pointed out.
An expression has been developed that generalizes three basic geometric schemes of film deformation (axial, planar, and biaxial extension) and also all intermediate schemes. The system of quantitative identification of nonuniformly biaxially oriented films according to their transverse extension has been tested on six different film types.
The main dependence for determining the energy-power parameters of processing the compositions, whose behavior under load is described by a power rheological law in the operation gap of mixers with oval rotors. In the proposed method of calculating the power of the mixer drive motor an attempt was made to account for movement of a treated material not only in circular but also in the axial direction of the mixing chamber. These dependences for determining the pressure and power supplied to the rotors for rotation thereof may be recommended for engineering calculations of mixing equipment for plastics and rubber mixtures.
