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Open pit coal mining enterprises are constantly faced with the task of increasing the economic efficiency of mining, reducing coal losses and increasing profitability. One of the ways to increase the efficiency of open-pit mining is the improvement of the technology for developing coal-bearing zones of quarry fields in sloped and steeply complex (hard-structured) deposits. Currently, projects for promising deposits have been completed, and a number of existing sections are developing coal-bearing zones across their entire width in horizontal layers. Extraction and loading equipment for stripping and winning operations in this area is characterized by a wide variety: rope shovels (also called power or stripping shovels), backhoes and hydraulic shovels or their joint work. When using only rope shovels or only backhoes, they produce an excavation of both interbeds and coal seams. When they work together in the coal-bearing zone, the rope shovel makes a stripping of the interbeds, and the backhoe – an extraction of the coal seams. However, such technical solutions are not sufficiently substantiated. The fact is that rope shovels and backhoe shovels have their advantages and disadvantages in operation.

The main problem of breast reconstruction after a mastectomy is the complete destruction of all structural elements of the breast and the lack of integumentary tissues that do not allow carrying out one-stage breast reconstruction. To solve this problem, usually performing a two-stage reconstruction, which today is the most commonly used method of breast reconstruction. The peculiarity of this method is that after removal of the expander, during the second stage of reconstruction, some retraction of the skin and a decrease in the area of the prepared skin cover are observed. Thus, after installing a permanent implant and suturing the surgical wound, the skin sheath is tightened around the installed endoprosthesis, while the greater the retraction of the skin, the more pronounced the tension appears and, accordingly, the load on the sutured wound increases. As a result, the risks of developing diastasis of the wound edges with the exposure of the endoprosthesis increase, which leads to the need to remove the implant. Therefore, when carrying out the second stage of breast reconstruction, a very important moment of the operation is the suturing of the postoperative wound, the competent implementation of which allows the prevention of implant extrusion.

An innovative core with an increased energy resource was used when designing RITM-200 reactor unit. The paper presents the results of experimental and numerical simulation of hydrodynamic processes occurring in the inlet region of the RITM reactor fuel assembly model. Computational mesh of fuel assembly, containing ~ 22 million elements was created using Ansys ICEM CFD. The values of relative axial velocities in several cross sections at the inlet to the bundle of fuel elements are obtained. At the inlet to the fuel rods bundle the velocity field is not uniform, due to the complex geometry of the fuel assembly. The obtained results of CFD-simulation can be used to determine the input boundary conditions for subchannel programs of the core thermal-hydraulic analysis. This allows taking into account uneven flow rate distribution in subchannels due to the complex geometry of the fuel assembly inlet region.

Currently, two types of handling machines are mainly used on coal open pit mines in Kuzbass, characterized by complex structural deposits: mechanical (rope) and hydraulic (backhoe) shovels. Moreover, both types of equipment are supplied to the quarries: mechanical shovels are purchased, as a rule, powerful with a bucket capacity up to 56 m3, backhoes – small and medium-size models with a bucket capacity of 2.8-14 m3. On the other hand, it is common to divide the areas of equipment use in the open pit on complex-structured deposits into a coalless (outside the strata of coalbeds) and coal-bearing (actually a series of beds, including coal strata and rock interbeds). The use of these equipment types in both design and industrial practice is observed in both zones. At the same time, it is known that each of these zones has different conditions for the efficient operation of excavation machines. The seams, therefore, do not complicate the coalless zone when working in it, favorable conditions are provided for the excavator: the constant height of the bench, which is necessary for the full filling of the bucket for one scoop, the constant width of the panel and the length of the front of the work. In these conditions, the maximum productivity of the excavator is ensured.

This article presents the results of an experimental study of the coolant flow in a fuel rod bundle of a nuclear reactor fuel assembly of a small modular reactor for a small ground-based nuclear power plant. The aim of the work is to experimentally determine the hydrodynamic characteristics of the coolant flow in a fuel rod bundle of a fuel assembly. For this purpose, experimental studies were conducted in an aerodynamic model that included simulators of fuel elements, burnable absorber rods, spacer grids, a central displacer, and stiffening corners. During the experiments, the water coolant flow was modeled using airflow based on the theory of hydrodynamic similarity. The studies were conducted using the pneumometric method and the contrast agent injection method. The flow structure was visualized by contour plots of axial and tangential velocity, as well as the distribution of the contrast agent. During the experiments, the features of the axial flow were identified, and the structure of the cross-flows of the coolant was determined. The database obtained during the experiments can be used to validate CFD programs, refine the methods of thermal-hydraulic calculation of nuclear reactor cores, and also to justify the design of fuel assemblies.

The use of algae for carbon dioxide fixation is based on their natural ability to photosynthesize. Dynamic experiments make it possible to calculate the short-term photosynthetic activity of microalgae strains in photobioreactors. In this study, the effect of temperature and culture time on the intensity of reproduction and on CO2 absorption by some microalgae was evaluated. It was found that the maximum increase in biomass occurred during algae cultivation at 29–32 °C and pH = 8.4. A ratio of ~2.0 was observed between CO2 absorption and the increase in biomass for different microalgae. When using the Chlorella genus, the increase in biomass under comparable conditions was greater than when cultivating microalgae of the Scenedesmus genus.

This article presents the results of an experimental study of the coolant flow in a fuel rod bundle of a nuclear reactor fuel assembly of a small modular reactor for a small ground-based nuclear power plant. The aim of the work is to experimentally determine the hydrodynamic characteristics of the coolant flow in a fuel rod bundle of a fuel assembly. For this purpose, experimental studies were conducted in an aerodynamic model that included simulators of fuel elements, burnable absorber rods, spacer grids, a central displacer, and stiffening corners. During the experiments, the water coolant flow was modeled using airflow based on the theory of hydrodynamic similarity. The studies were conducted using the pneumometric method and the contrast agent injection method. The flow structure was visualized by contour plots of axial and tangential velocity, as well as the distribution of the contrast agent. During the experiments, the features of the axial flow were identified, and the structure of the cross-flows of the coolant was determined. The database obtained during the experiments can be used to validate CFD programs, refine the methods of thermal-hydraulic calculation of nuclear reactor cores, and also to justify the design of fuel assemblies. [ABSTRACT FROM AUTHOR]

The paper presents experimentally determined hydrodynamic characteristics of the coolant flow at the outlet of the RITM nuclear icebreaker reactor fuel assembly. The studies were carried out according to Pitot tube measurements based on the theory of hydrodynamic similarity using a model of the fuel assembly outlet with an air working medium. Friction factors were determined for several sections located at the outlet of the fuel assembly. The distribution of the hydrodynamic characteristics of the coolant flow is visualized by cartograms of the axial velocity at the outlet of the fuel rod bundle, in the wide and narrow parts of the nozzle, as well as in the fragments of drain windows in the upper base plate. The flow of the coolant through the central displacer and pipe for conducting the coolant to the resistance thermometer is determined. According to the performed studies, the asymmetric nozzle, coolant sampling pipe of the resistance thermometer, and upper base plate are the essential parameters affecting the formation of the field structure for the axial flow velocity. [ABSTRACT FROM AUTHOR]

The efficiency of heat transfer in air-cooled heat exchangers of various industrial facilities depends on the flow rate of the coolant, its inlet temperature and ambient temperature. These parameters are transient and depend both on the features of the technological process and on weather conditions. One option for a compact design of heat exchangers is the use of close-packed coils with a small bending radius. In this case, heat transfer in the complex geometry of the annular space cannot be described by simple one-dimensional dependencies. To solve this problem, it is necessary to consider the three-dimensional spatial structure of the heat exchange surface. Since the size of the grid elements will be several orders of magnitude less than the size of the facility, the size of the computational grids for CFD modeling full-scale heat exchangers will be billions of finite volumes, and even on powerful supercomputers, the solution time will be about a month. One way to reduce computational costs is to use reduced order models, in which the computational domain is not modeled directly; instead, simplified models, such as a porous medium model, are used to describe it. However, such models require additional closing relations and coefficients that characterize the actual channel geometry. This paper presents a technique for creating a digital twin of a heat exchanger with small bend radius coils based on a porous medium model. The values of heat transfer coefficients and hydraulic resistance depend on the speed of air movement in the space between the coils. The calculated value of the thermal power obtained using the strengthened model was 529 kW, which corresponds to the passport data of 500 kW, with less than 6% deviation for the heat exchanger under study. This confirms the correctness of the calculation with accepted simplifications. The calculation time in this case was only a few minutes when using a personal computer. The developed numerical model allows for the resolution of performance characteristics based on the temperature of the cooled medium at the inlet, air temperature, and fan speed. Analyzing the different modes of turning on the cooling fans made it possible to determine the values of the thermal power when turning off the fans or reducing the number of revolutions.