In this work, surface mechanical attrition treatment (SMAT) was employed to rejuvenate ZrCuAlNi bulk metallic glass (BMG) plate. Differential scanning calorimetry (DSC), atomic force microscopy (AFM) and nanoindentation analyses were carried out to evaluate stored energy and micro-mechanical properties of treated BMGs. According to DSC results, 10 min SMAT process increased the stored energy of BMG plates up to 50%. AFM analysis showed that the structural rejuvenation occurred in the bulk of samples and just a slight rejuvenation gradient was detected from the front to the back side of BMG plates. Nanoindentation analysis indicated that the structural rejuvenation is consistent with anelastic strain induced under the SMAT process. It was also found that an optimum treatment time is needed for maximum rejuvenation in the BMGs. This event is due to the fact that the glassy structure is able to store a critical anelastic strain, which leads to a saturated condition in rejuvenation.

The study of the influence of the degree of contamination of low-temperature heating surfaces on the intensity of convective heat transfer during the burning of non-design fuel based on computer modeling has been carried out. The results of the analysis showed that the amount of deposits varies depending on the temperature of the heat carriers in the air heater. A new method for calculating the thermophysical parameters of the heat transfer process has been developed on the basis of the ANSYS software package, which makes it possible to obtain a complete description of complex heat transfer processes in the boiler air heater. In the developed computational three-dimensional thermophysical model of a recuperative tubular air heater, there is no tube wall; the created thermal resistance of the wall is taken into account by introducing the coefficient of effective thermal conductivity of the flue gas flow.

The paper investigates the mathematical modeling of anaerobic fermentation for the utilization of animal wastes. It analyzes various approaches to the mathematical modeling of anaerobic digestion processes. However, most of the models previously proposed do not take into account a number of key parameters such as the levels of micro and macronutrientls (such as K, Na, Ca, Mg, Mo, etc.), values of volatile fatty acids, C/N ratio, pH levels, extent of grinding, moisture, and others. This paper proposes a new mathematical model of anaerobic fermentation under industrial scale conditions. The model was developed on the basis of regression analysis and correlation. It found empirical relationships between biogas yield and 26 different parameters. These parameters are measured by appropriate biosensors in industrial production. Some of them have more significant influence on the fermentation process than others. Overall, the developed mathematical model has the potential to provide useful insights into biogas production and can be used to optimize anaerobic fermentation processes.

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