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An experimental study of the formation of the structure of a closed vortex motion of a liquid in a vertical cylindrical container with a rotating end (disk) under various boundary conditions has been carried out. The regimes of formation of the circulating motion of a liquid with a small aspect ratio are experimentally investigated. The studies have been carried out using the Particle Image Velocimetry method in a horizontal cross-section near the interface in a cylinder and near the bottom in a gas-vortex reactor. It has been found that with a small aspect ratio in an open cylinder near the air-liquid interface, a region is formed near the axis, in which the radial velocity component is close to zero. Consequently, the circulation is not formed in the entire volume, and the efficiency of mass transfer decreases. At the same time, at a solid boundary, as well as at the liquid-liquid interface, a circulation flow of the working fluid is formed even at a small aspect ratio.

The article considers the using intelligent controls possibility in low-voltage rural electric networks to minimize the unbalance modes consequences. The proposed technology includes the digital data transmission compilation on the electrical energy parameters with a new balancing technical means the electrical network operating mode. Digital feedback is provided for changes the balancing device (BD) parameters by the unbalancing power consumption changing level. Based on the developed methods compilation, software for calculating unbalancing modes has been created, which makes it possible to assess the currents and voltages unbalancing effect on the power quality and its additional losses change. The “green” technology proposed version, which increases the economic and the electric energy environmental safety use in the rural electric power industry, contains a new constructive solution for the balancing device implementation. The proposed technology was tested on the measurement data basis in existing electrical networks. Based on the MALAB technologies use, changes studied indicators visualization in the before and after BD integration in the electrical network was carried out and its analysis was makes. Used on the “neural networks” MALAB technology, a preventive assessment of the unbalancing power consumption events development in the investigated operating electrical network is presented, as well as the proposed technology effectiveness assessment was carried out.

Violation of the symmetrical mode of operation of the electric network causes a deterioration in the quality of electric energy and significantly reduces the reliability of the functioning of electrical equipment and elements of the electric network. A mathematical model of an electrical network with a grounded neutral is proposed аnd a software package that allows us to evaluate the level of voltage asymmetry of a three-phase system depending on the changing unbalanced load was created. The simulation and calculation of the studied parameters for various combinations of loads and the technical means of balancing the operating mode of the electric network (the balancing device – BD) is carried out. Programs for the Matlab graphic editor are compiled and diagrams of changes in electricity quality indicators are constructed. A numerical analysis is carried out and recommendations are given to determine the most appropriate place for connecting the BD in the electrical network to improve the quality of electricity based on the calculation made.

The article discusses distribution electrical networks 0.38 kV operating modes, feeding individual residential buildings. The electrical energy parameters measurement were certified RESURS-UF2M device carried out. The currents and voltages time diagrams based on the measurements made and using Matlab technologies were constructed. It is established that the level of phase currents unbalance is quite high and causes significant three-phase power supply system unbalance voltage accordingly. The power of quality indicators - calculations, characterizing voltage unbalance were made, which were based on the measurements and the computer program “Asymmetry” was used. As well as the additional power losses coefficient determining by the phase currents unbalance, were calculations. Time diagrams these indicators are constructed and their analysis were made. As a result, the power of quality is significantly reduced by unbalance power consumption in the studied electrical network were founded. At the same time, the additional power losses are significant increases. Specific recommendations for the normalization electrical network-operating mode are given.

The article presents calculations the additional electric loss in the case of three-phase voltage system unbalance in the real rural electrical distribution networks (0.38 kV). Measurements were carried out at substations that receive power from distribution substation “Petropavlovsk”. Measurements were carried out using a certified device “Resource-UF2M”. Also presented are graphs of changes in currents/voltages of the negative-sequence and zero-sequence, electric loss and other parameters. The results of the economic assessment of electricity losses are presented. As a result, the proposed method for reducing the power loss factor, that can reduce the losses of electricity.

Forecasting of level of reliability of power supply of consumers is one of the major tasks at implementation of actions for improvement of operational characteristics of distribution electrical networks. On the one hand, assessment of damageability allows to develop a number of actions for increase in reliability of electric equipment and elements of electrical networks, with another, to create a stock of that equipment which is subject to risk of premature failure. The purpose of the present article is implementation of statistical assessment of damageability of basic elements of distribution electrical networks of 10 kV on the basis of the predicted information on possible refusals in these networks. The main objectives for achievement of the specified purpose are: 1. Implementation of preventive assessment of refusals in electrical networks on the basis of data of dispatching magazines of observations; 2. Statistical assessment of casual events of failures of electric equipment and detection of their laws of distribution.

The guidelines for the design of rural and urban power supply systems do not consider the issues of reactive power compensation and reduction in additional losses due to unbalanced and non-sinusoidal conditions. At the same time, today’s rural power consumers have a great number of non-linear loads in their residential premises. Moreover, the unbalanced phase currents and voltages are an established fact. The paper aims to demonstrate the extent to which power quality and losses vary in real rural 0.38 kV networks. To this end, the objectives were posed to study the operation of two facilities: 1- switchgear at the cottage (with an installed capacity of 15 kW); 2- switchgear at the communal entrance hallway for 60 apartments in an apartment building (with an installed capacity of 75 kW).

The paper reports the results of experimental and numerical studies of vortex motion in an industrial-scale glass bioreactor (volume, 8.5 L; reactor vessel diameter D, 190 mm) filled 50–80%. The model culture medium was a 65% aqueous glycerol solution with the density ρg = 1150 kg/m3 and kinematic viscosity νg = 15 mm2/s. The methods of particle image velocimetry and adaptive track visualization allow one to observe and measure the vortex motion of the culture medium. In this work, the vortex flow investigation was performed in a practical bioreactor at the operation regimes. Our research determines not only the optimal flow structure, but also the optimal activator rotation speed, which is especially important in the opaque biological culture. The main result is that, similar to the case of two rotating immiscible liquids, a strongly swirling jet is formed near the axis, and the entire flow acquires the pattern of a miniature gas–liquid tornado. The aerating gas interacts with the liquid only through the free surface, without any mixing. This intensifies the interphase mass transfer due to the high-speed motion of the aerating gas. [ABSTRACT FROM AUTHOR]

Introduction: Significant psychophysiological burdens and unhealthy lifestyle constitute the risk factors leading to students' health deterioration. Purpose: The purpose of the research was the analysis of students' health condition and lifestyle in medical university. Material and methods: The objects of the research were 100 third year students of the Faculties of General Medicine and Pediatrics of Grodno State Medical University. For the study of students' orientation on healthy lifestyle, a special scale-type questionnaire was developed and used. Results: According to the respondents' opinions it has been detected that the basic factors influencing the state of health are the lifestyle and the living conditions. The students activity is evaluated as very low as well as their rational nutrition. The majority of them smoke and drink alcohol. Conclusions: The peculiarities of studying at a medical university accompanied by imbalanced nutrition might lead to the deterioration of health in the students which are doctors to be. The results ought to lead to the optimization of prophylaxis programs and entire alteration of the students' lifestyles. [ABSTRACT FROM AUTHOR]

• Experimental study of swirling two-fluid flow in a vertical cylinder. • The rotating lid drives a steady axisymmetric circulation. • A jump of a swirl velocity at the interface is observed. • The Moffatt eddy occurs near the interface-sidewall intersection. • The results can be important for bioreactors. Recent theoretical and numerical studies predict the Moffatt eddies near the interface-wall intersection in a two-fluid flow. The current work provides the first experimental evidence of this phenomenon of fundamental interest. It also reveals a jump of the azimuthal velocity at the interface which can be important for vortex bioreactors. The rotating lid drives a two-fluid flow in a vertical cylindrical container whose other walls are stationary. Near the lid, the centrifugal force pushes the upper fluid to the sidewall thus developing its centrifugal meridional circulation. This motion drives the bulk counter-circulation and the Moffatt eddies in the lower fluid at a slow rotation. Using sunflower oil for the upper fluid, water-glycerin or alcohol-glycerin solutions for the lower fluid, and assemble averaging of PIV images allow for velocity measurement and flow visualization even in a creeping motion. This advanced experimental technique helps detect velocity jumps, occurring at the interface and the Moffatt outermost eddy. [ABSTRACT FROM AUTHOR]