Design of Computational Models for Hydroturbine Units Based on a Nonparametric Regression Approach with Adaptation by Evolutionary Algorithms

This article deals with the problem of designing regression models for evaluating the parameters of the operation of complex technological equipment—hydroturbine units. A promising approach to the construction of regression models based on nonparametric Nadaraya–Watson kernel estimates is considered. A known problem in applying this approach is to determine the effective values of kernel-smoothing coefficients. Kernel-smoothing factors significantly impact the accuracy of the regression model, especially under conditions of variability of noise and parameters of samples in the input space of models. This fully corresponds to the characteristics of the problem of estimating the parameters of hydraulic turbines. We propose to use the evolutionary genetic algorithm with an addition in the form of a local-search stage to adjust the smoothing coefficients. This ensures the local convergence of the tuning procedure, which is important given the high sensitivity of the quality criterion of the nonparametric model. On a set of test problems, the results were obtained showing a reduction in the modeling error by 20% and 28% for the methods of adjusting the coefficients by the standard and hybrid genetic algorithms, respectively, in comparison with the case of an arbitrary choice of the values of such coefficients. For the task of estimating the parameters of the operation of a hydroturbine unit, a number of promising approaches to constructing regression models based on artificial neural networks, multidimensional adaptive splines, and an evolutionary method of genetic programming were included in the research. The proposed nonparametric approach with a hybrid smoothing coefficient tuning scheme was found to be most effective with a reduction in modeling error of about 5% compared with the best of the alternative approaches considered in the study, which, according to the results of numerical experiments, was the method of multivariate adaptive regression splines

X-ray Diffraction Phase Analysis of Changes in the Lattice of Pervouralsk Quartzite upon Heating

At present, quartzite is widely used across many industries. The properties of quartzite significantly affect the technology used during the preparation of the raw materials as well as the technology used for manufacturing the final product, which may be intended for further operation at different temperatures. The purpose of the study was to create a scheme for the transformation of quartzite that would describe the changes in the parameters of its lattice parameter upon heating and would offer guidance regarding the drying technology and technology required to obtain tridymite. A Bruker D8 Advance diffractometer was used to study changes in the phase composition of quartzite at the temperatures of 200, 400, 600, 879, 1000, 1200, 1470, and 1550 °C. A detailed scheme of transformations of PKMVI-1 quartzite with a SiO2 content of at least 97.5% at normal pressure was proposed for crystalline modifications formed during its heating. As a result of this research, the changes in the parameters of the lattice parameter—such as the average interplanar distance davg, the volume of the unit cell Vavg, the density of the unit cell Davg, and the molecular weight Mavg—were established

The Technology of Using Liquid Glass Mixture Waste for Reducing the Harmful Environmental Impact

The spent liquid glass mixture, which is widely used in foundries as a binder after knocking out of moldings, contains pieces of different sizes and strengths, and there is a strong silicate film on the sand grains themselves. The proposed regeneration plants, which provide for the removal of the silicate film by scrubbing, have low productivity and lead to abrasion of the grains themselves. For this reason, the knocked-out mixture is taken to the dump. As a result of the study of the state of the spent liquid glass mixture in the dump, it was found that, in the spent mixture that had lain for 8–10 years, under prolonged exposure to atmospheric precipitation at plus and minus temperatures, part of the silicate film dissolves and almost all monolithic pieces are destroyed. Further use of hydraulic regeneration allows us to reduce the film thickness and thereby reduce the percentage of liquid glass from 5–5.5% to 0.8–1.2%. This made it possible to select the composition of the molding sand for an automatic line, using the AlpHaset-process, which consists of 22–29% of liquid glass mixture from a dump, 65–72% of liquid glass, 5.5% of liquid glass, and a hardener in the amount of 0.55%

X-ray Diffraction Phase Analysis of Changes in the Lattice of Pervouralsk Quartzite upon Heating

At present, quartzite is widely used across many industries. The properties of quartzite significantly affect the technology used during the preparation of the raw materials as well as the technology used for manufacturing the final product, which may be intended for further operation at different temperatures. The purpose of the study was to create a scheme for the transformation of quartzite that would describe the changes in the parameters of its lattice parameter upon heating and would offer guidance regarding the drying technology and technology required to obtain tridymite. A Bruker D8 Advance diffractometer was used to study changes in the phase composition of quartzite at the temperatures of 200, 400, 600, 879, 1000, 1200, 1470, and 1550 °C. A detailed scheme of transformations of PKMVI-1 quartzite with a SiO2 content of at least 97.5% at normal pressure was proposed for crystalline modifications formed during its heating. As a result of this research, the changes in the parameters of the lattice parameter—such as the average interplanar distance davg, the volume of the unit cell Vavg, the density of the unit cell Davg, and the molecular weight Mavg—were established

Influence of Moisture in Quartzite on the Lining Properties and Efficiency of Industrial-Frequency Induction Crucible Furnaces

The main purpose of industrial frequency induction crucible smelters (IGM) is the smelting of synthetic cast iron, using metal filling scrap in the amount of 30–35%, at a temperature not exceeding 1450 OZ C. The basis of the lining used is quartzite, which undergoes polymorphic transformations in the pre-treatment process to form tridimite. The efficiency of using these furnaces is significantly increased when using a metal casting consisting of a single steel scrap, but for this purpose, the melting mode has to be raised to 1550–1600 °C, which will reduce the resistance of the lining. The structural transformation of quartzite is strongly influenced by the state of water in it. In this work, studies have been carried out for changes in the water condition in the quartzite of the brand PCMVI-3 under the action of temperatures of 200–1550 °C. The Shimadzu XRF-1800 spectrometer established the actual chemical composition of the investigated quartzite and found that the amount of impurities in it is 0.66%. A derivative study of STA 449 F1 Jupiter found two endothermic effects. The first, at 170 °C, relates to the loss of adsorbed water. The second, at a temperature of 570 °C, passes without the loss of mass of the sample, and it is accompanied by the beginning of the process of the destruction of point defects in the form of Al-OH groupings. From a temperature of 620–630 °C, no mass changes associated with water removal were detected. The BRUKER D8 ADVANCE diffractometer investigated phase changes during the removal of moisture from the quartzite at temperatures of 200 and 800 °C and subsequent cooling and then during the heating used to sinter the lining. As a result, it has been established that the sheet in which the quartzite contains only chemically bound moisture, after sintering, turns into cristobalite and provides a more stable exposure to sudden temperature changes. This makes it possible to use up to 90% of the steel scrap in metal filling, which increases the efficiency of the melting furnace and the production of castings in general