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The purpose of the article is to study the possibilities of preventing the imbalance caused by the stochastic nature of RES by regulating the electricity accumulation and the backup generator. The subject of the research is random processes of energy generation and consumption. The goal is achieved by a mathematical model construction in which the system parameters would be formalized and allow the choice of optimal options. The mathematical model uses random functions to obtain statistical estimates, and is implemented as sequential models of energy generation and consumption as an integrated random process. The models’ adequacy is confirmed by comparing the simulated and real indicators for a number of existing RES in Ukraine. The proposed approach made it possible to establish the presence of system parameters that minimize energy losses and consumption, reduce the probability of energy imbalance, and effectively use the reserve power. The proposed mathematical model allows determining the probability of various system states, it estimates the reliability of energy supply, and minimizes losses at the stages of designing a power system and planning its operating modes. The above estimates are typical for certain climatic conditions and modes of energy consumption, and are of a specific nature. The significance of the work lies in the fact that the proposed formulation of the problem makes it possible to adapt the mathematical model to various conditions, to find implicit dependencies between the technical parameters of the system and its indicators in order to find optimal solutions.

The article is dedicated to the study of random parameters describing the processes of electric energy consumption in power systems of different levels of localization. The objective of this research is to construct the mathematical model that adequately describes consumption modes as random processes. As experimental studies, we statistically processed the data on energy consumption of several settlements, regional and integrated energy systems of Ukraine for 2015-2017. The results obtained were used as the base for developing and testing the mathematical models. To achieve this goal, representations of the model parameters as random variables were used, and the results of simulation were compared with experimental data. The scatter of drift values is generally greater than volatility. When a group of consumers is combined or the size of the local power system increased, the spread of parameters expectedly decreases. The most significant result of the research is establishment of probability distribution laws for the parameters of the process of electric energy consumption. For the indicator of volatility, it can be considered as Gaussian. The drift index is well described by the Weibull distribution. We estimated the size of a random sampling of experimental data needed to obtain statistically stable results. Significance of the obtained results consists in establishing the degree of consistency of the actual data and random implementations of the simulation model, which proves adequacy of the proposed mathematical model and makes it possible to assess the real uncertainty of the process of balancing the power system.

The work deals with the study of secondary-phase precipitation in binary and ternary zirconium-based alloys with extra-small content of doping within the framework of the phase-field approach. Developed phase-field model is applied to study β-phase precipitation in the model system of commercial Zr-Nb-Sn and Zr-Nb alloys at thermal treatment. An analysis of local rearrangement of doping and equilibrium vacancies during precipitation is provided. Kinetics of precipitation, size and distribution of the precipitates, concentration of the species in precipitates and matrix are studied. Mechanical response including the plastic deformations in precipitated solid is discussed. As shown, the yield-strength change increases during precipitation. Yield and ultimate strength are studied at different shear rates for the annealed alloy. Formation and growth of slip planes and dislocation loop-precipitate interaction governed by elastic-moduli difference is analysed. As shown, the emergence of dislocation loops around precipitates follows the Orowan's mechanism. Modelling the radiation-induced precipitation during neutron irradiation of zirconium alloys with low content of doping is performed within the framework of the developed phase-field model by taking into account ballistic mixing and the dynamics of point defects with their sinks. As shown, in a sample initially containing precipitates of the secondary phase, irradiation results in the dissolution of precipitates at small doses and reprecipitation with dose accumulation. Analysis of precipitation dynamics and statistical distributions of precipitates with local rearrangement of non-equilibrium vacancies around precipitates at neutron irradiation is provided. As shown, the competition between the ballistic mixing and the thermodynamic force plays a major role in kinetics of radiation-induced precipitation and precipitates' dissolution. The estimation of mechanical properties of Zr-Nb alloy during irradiation under reactor conditions is provided. [ABSTRACT FROM AUTHOR]

The purpose of the research is to determine criteria and calculate optimal ratio of different renewable energy sources (RES) for hybrid systems, estimate the random component of power fluctuation and consider the opportunities for its minimization. As a subject of the study it is variable and poorly forecasted in a short-term prospect character of generated power can negatively affect modes of grid operation. This concerns stability of dynamic processes in the systems of power supply. To develop a mathematical model of these processes a number of factual data on the climatic parameters and energy consumption regimes during the joint operation of solar and wind stations was used. As an experimental study suggests, the initial data were collected and statistically processed. Based on the results, mathematical models were developed in the form of a composition of deterministic and stochastic components and theoretical studies on the search for optimal ratios of capacities of wind and solar power stations were carried out. The object of optimization in the work is the load variability. As a combined single criterion, it was proposed to use the coefficient of variation. The ratios of the wind and solar components of the power generation, considered in this study, has allowed us to determine variants with a minimal dispersion of RES generation or with a minimum ratio of dispersion to average generated power which depends on the average annual or seasonal weather conditions. As a rule, the share of wind power plants should be 10-40% of the total rated RES power, depending on the total share of RES.

This work is devoted to a comprehensive detailed study of a pure zirconium with non-equilibrium point defects induced by irradiation within the framework of the multiscale modelling scheme by using quantum-mechanics methods, molecular dynamics, and the Monte-Carlo methods based on the Langevin dynamics. By using ab-initio calculations, the structural, electronic, and energy properties of a pure zirconium with isolated vacancies and their clusters are studied. The lattice-parameter change in pure zirconium with different concentrations of isolated vacancy and different configurations of di- and trivacancies is discussed. The vacancy-formation energy in a pure zirconium is obtained. Stability of small vacancy clusters containing divacancy characterized by different distances between two vacancies as well as trivacancies of different configuration is analysed. Distributions of electron density, band structure, and Fermi surface for pure zirconium with isolated vacancy are studied in detail. We calculate the dependence of the Fermi energy of a zirconium crystal, whose unit cell contains a vacancy cluster, on the number of vacancies in the cluster. Cascade formation, development, and annealing in pure zirconium crystals irradiated in different irradiation conditions are studied within the framework of the molecular-dynamics simulations. Statistical and geometric properties of cascades are examined in detail by varying sample temperature, energy of primary knocked atom, and direction of its motion. A possibility of channelling at cascades’ development resulting in formation of crowdions is shown. A change in statistical properties of the crystal during cascade development and relaxation time of cascades is calculated. Dependence of formation energy of point defects and vacancy clusters on temperature is discussed. Spatial self-organization of an ensemble of point defects in α-zirconium irradiated by fast neutrons by using reaction rate theory is studied. In our consideration, we take into account elastic properties of the medium due to defects’ presence and sink density dynamics. We consider dynamics of the system with uniform distribution of point defects and spatially extended system at different irradiation regimes (by varying irradiation temperature and dose rate). As found, the point defects’ patterning is accompanied by a formation of vacancy clusters. The distribution of elastic fields with the self-organization of a vacancy ensemble in a pure zirconium subjected to shear and cyclic deformation and the impact of irradiation on the mode of deformation of zirconium are studied.

Average daily or monthly data of solar radiation are often used in statistical analysis and in development of mathematical models for predicting energy generation. However, this can have a negative impact on the accuracy of forecasting. The authors carried out the statistical analysis of solar radiation based on the data obtained from the Tokmak SPS of the Zaporizhia region, Ukraine during 2016. The data were collected with a 30-minute interval in measurement. The analysis indicates close values of winter and summer insulation indices (direct and scattered), where the difference is approximately double. The mathematical expectation of the power surges is close to zero, and their distribution has signs of symmetry. The results of actual data calculation indicate that values of the elementary power surges of the SPS are a bit higher than the normal distribution calculated. Thus, the actual distribution corresponds to the normal one in the parameter of symmetry, but does not correspond to the parameters of kurtosis. If the time range is doubled from 30 minutes to 1 hour, the range of power changes slightly increases. In addition, the analysis of meteorological data showed that the probability of a prolonged growth or decline in power is not high, i.e. a change in power as a random process can be considered close to the stationary one. The performed analysis estimates the power supply possibilities for the region’s consumers by the solar power plant, and creates a mathematical model for operation of the combined energy system that uses solar energy.

The review is devoted to one of the urgent tasks of our time the morphological diagnostics of tuberculosis in association with HIV infection. The last decades in Ukraine there has been a continuous increasing of the incidence of cases of co-infection, which makes it important a diagnosis in-time, and that is reflected in a number of publications. Modern approaches to the morphological diagnosis of tuberculosis/HIV are presented, which prove that the histological signs of a tuberculosis lesion depend on the priority of infection of patients by HIV or TB (HIV/TB or TB/ HIV), on the degree of immunodeficiency, and possible joining of other secondary infections. There are presented studies in which it was established that in the case of a primary infection by HIV infection, and then tuberculosis, the generalized forms of the latter predominate, atypia of morphological changes in lung tissue is observed, with a predominance of alterative-necrotic manifestations and a weak granulomatous reaction. On the contrary when primary infection is tuberculosis, and then HIV, in the lung tissue signs of a specific inflammatory process in the form of fibro-cavernous or disseminated pulmonary tuberculosis usually remain, although the morphological signs of progression of tuberculosis in the form of caseous pneumonia are revealed simultaneously. It is noted that the main morphological characteristic of the lungs during co-infection is the varying degree of loss of morphological signs specific for tuberculosis, which depends on the level of immunodeficiency, the last is determined by CD4 + lymphocyte count in the blood. With immunodeficiency with a level of CD4 + cells in the blood less than 150200 cells/?l, the morphological picture of the lungs becomes similar to abscess pneumonia with a significant necrotic component, single granulomas and the absence of multi-nuclear giant cells. In case of mild immunodeficiency (the number of CD4 cells is more than 500/?l in blood), typical granulomatous inflammation is observed in the lung tissue. Modern histological methods for identifying of acid-resistant bacteria in tissues that are used in practical medicine are presented, but their common drawback is the impossibility of determining the type of mycobacterium. The latter remains the prerogative of microbiological research. There is evidence that the joining of numerous opportunistic infections in patients with co-infection, especially in the late stages of HIV, greatly complicates the diagnosis and often leads to a delay in correct diagnosis. For early timely diagnostics of tuberculosis at co-infection, it is most appropriate to perform a set of diagnostic procedures, in particular, modern fast molecular genetic, immunological diagnostic methods, which in cases of uncertainty of the results, require the additional use of classical and improved morphological methods for diagnosing tuberculosis.

The aim of the paper is to study the possibilities of providing the local consumer with electricity from renewable sources to reduce dependence on centralized supply. The peculiarity of the task is the random influence of renewable energy and consumption on ensuring the energy balance in the local power system, by choosing the composition and capacities of renewable generation and auxiliary equipment. A storage battery and a conventional fuel generator are considered as auxiliary balancing equipment. A simulation model was applied, which allows taking into account the peculiarities of this system and the nonguaranteed nature of the power of solar or wind plants. The components of the power balance are described as the decomposition of a certain random process, which is a feature of this model. The volume of needs for energy flows between local and centralized energy systems, their variability with different parameters of accumulation and auxiliary generator is calculated. The combination of wind and solar energy makes it possible to reduce dependence on the general electricity grid. The same result is provided by the use of intermediate energy accumulators and an auxiliary source such as a diesel generator. A comparison of the energy balancing indicates the different role of wind and solar energy at different times of the year: the use of installed capacity and the level of energy consumption can vary significantly. Other influencing factors are the speed of battery charging and energy loss during conversion - the consequence is the need for different duration of operation of the auxiliary generator and frequency of its activation. The reliability of the simulated results is verified by comparing them with real examples, the differences are at the level of 5-10 %. The proposed model allows us to choose the configuration of generating and auxiliary equipment with a known mode of electricity consumption, and to evaluate the possibilities of ensuring the energy balance. Bible 23, fig. 3, tab. 9. [ABSTRACT FROM AUTHOR]

We extend reaction rate theory to study dislocation loops growth and associated radiation growth in binary Zr-Sn alloys under neutron irradiation at reactor conditions. A model to describe experimental data for loops' number density is proposed. We discuss dose dependences of dislocation loop radii, their densities and growth strains and analyse an influence of irradiation temperature and sinks' strengths on statistical properties of loops. A competition between the interstitial and vacancy -type loops is studied. Local loops distribution inside grains is analysed. Estimation of hardening of material is provided. Obtained results are compared with experimental observations. [ABSTRACT FROM AUTHOR]