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The purpose of this paper is to present an analysis about the methods, which can be applied to optimize the oil and gas supply chain, in the context of globally environmental challenges. The regional legislation backgrounds regarding the environment, mainly based on social and economic reasons, are becoming more and more important. The European Union (UE) is a first example of applying the regional environmental principles and objectives by means of the legislation of member national states, the European fundamental principles being preventive measures, ‚the one causing pollution has to pay’, as well as integrating the environment in other community policies. Economic development has recently started to focus mainly on the renewable resources. The fast increase of demand in the developing countries has led to a constant growth in the consumption of non-renewable resources, including oil and gas. Liquid fuels will continue to be the main source of energy, and their consumption will keep on growing despite of their price escalation. Similarly, the world consumption of natural gas is expected to rise globally. The current paper will present a theoretical optimization models, applied in oil and gas industry to optimize oil and gas extraction process. [ABSTRACT FROM AUTHOR]

This paper intends is to analyze and give a functioning overview of the national protection and competition development authorities in the Western Balkan countries. To explain how much these authorities are in compliance with EU rules and activities, to detail the implementation level of competition rules, to provide an overview how far these countries are in fulfilling their obligation based on Stabilisation and Association Agreement. Also, this paper intends to find the formula to build a strong and efficient National Competition Authorities as a prerequisite to ensure the effective implementation of the law on protection of competition and market economy functioning. Finally, the paper shows the level of implementation of competition rules from these candidate countries for EU membership in accordance with EU directives dealing with prohibited agreements, abuse of dominant position, concentration and state aid. Finally, the paper shows the level of implementation of competition rules from these candidate countries for EU membership in accordance with EU directives dealing with banned agreements, abuse of dominant position and state aid. [ABSTRACT FROM AUTHOR]

Paper focused on extension of usage of the AutoID model of transport system in laboratory. Transport model is equipped by complex AutoID system based on RFID and magnetic sensors. They are used to gather information from transport processes. The aim of solution presented in paper is to describe data flows in this physical model and to design representation of data flows and processing in simulation system Witness. This kind of model can better present behavior of data background to students and make them better understand principles. Further development is discussed too. We suppose to use real data from the model to be processed in simulation environment. Presented model is part of simulation model created for support of education of branches Information for logistics and Transport logistics for bachelor's degree students and Logistics for master's degree students. [ABSTRACT FROM AUTHOR]

The forecast of a convective situation is achieved not only through the analysis of the synoptic situation as well as with the help of instability indicators. These are determined either by means of data obtained from aerologic surveys or by using numerical models. The data presented in the paper are obtained using the model ALADIN (Aire Limitée Adaptation Dynamique Développement InterNational) model. Run instability indicators were KI, TTI (Total Totals Index) and CTI (Cross Totals Index) CAPE and MOCON. The analysis focused on 18 representative cases of instability during the period 2005- 2009, that affected western Romania, with a frontal nature as well as in the same air mass, for the analysis of the relationships between instability indicator thresholds, convective structures and associated radar echoes. For this paper, we chose a representative case describing a mesoscale convective system associated with the meteorological phenomena typical of a supercell. Atmospheric instability is manifested by a wide range of phenomena that led to damage and, in the most unfortunate circumstances, to human victims. The case observed storms, hail, torrential rains, not mentioning the "ordinary" thunderstorm phenomena. The case differed from others for at least two reasons: the front passage during the night was preceded by prefrontal mass instability and the mesoscale convective system has benefited from the contribution of two consecutive supercellulare structures, with considerable vertical development. [ABSTRACT FROM AUTHOR]

The paper suggests a mathematical model, which is to evaluate interaction of a wheeled mover and forest soil. The model is composed by compiling results, which were obtained by independent researchers in the framework of vehicle locomotion theory under off-road conditions and authors' obtained dependencies. In particular, the model includes refined formula for calculating shape of contact area with the ground (formula allows to take into account the deformation modulus effect on contact area shape), for calculating mover's radial deformation (formula allows to take into account the tire inner pressure, mover geometry, soil and mover deformation consistency), for accounting time of ground stress (the formula is to assess the impact of wheel speed on ground deformation), for assessing soil shear strain. The article describes calculating procedure for the proposed model and gives examples of calculation results (estimate rolling resistance coefficient, thrust coefficient, drawbar pull coefficient for given values of mover's diameter, width, inner tire pressure, speed, rut depth and adjusted wheel load). The results establish non-linear relationships between rolling resistance coefficient, the net thrust coefficient and the drawbar pull coefficient and the inputs. The paper also provides simplified mathematical models for engineering calculations of rolling resistance (depending on the deformation modulus, tire width, wheel diameter, adjusted wheel load and the inner pressure in the tire), net thrust coefficient (depending on the soil deformation modulus, tire width and the slip ratio) and the drawbar pull coefficient (depending on the deformation modulus, tire width, wheel diameter, adjusted wheel load, inner pressure in the tire and the slip ratio). These models come as results of computational experiment with proposed formulae sets. [ABSTRACT FROM AUTHOR]

General topic of this paper is numerical modelling of pollution dispersion in streams and use of some modelling approaches for the inverse task. Inverse task means a modelling technique, which is focused on the localisation of unknown pollution source. Such task is called „inverse”, because typical common models or equations are rather focused on the pollution spreading simulation, whereas the pollution source location is known. To solve such inverse problem various approaches can be used, but in all cases a prerequisite is to know pollution concentration time courses in the monitored stream section. One of the simplest approaches for solving the inverse task is to perform a large number of plausible simulations and to compare the simulated concentration time courses with the monitored one. The best fit can determine the distance of the pollution source. For such inverse task solution, a simple and fast modelling method should be used, but on the other hand the method should be as precise as possible. This paper proposes an improvement of the analytical method, which can be used for the inverse task solution. [ABSTRACT FROM AUTHOR]

Higher complexity of modern constitutive models often results in an increase of number of input parameters and time requirements for their calibration. Optimization methods provide a possible solution for this problem. A program application based on the metaheuristic optimization method Particle swarm optimization (PSO) is presented in the paper. The application consists of two parts: a subroutine with the PSO algorithm and a subroutine involving a finite element (FE) model of an analyzed construction. The subroutine with PSO governs input parameters modifications and evaluation of the objective function. Modified values of input parameters are then used in the FE model subroutine for calculation. Different alternatives of the PSO method are reviewed and tested in the first part of the paper. In the second part, a synthetic numerical experiment of pressuremeter test is used for automatically driven determination of input parameters for two constitutive models: Mohr - Coulomb, Hardening soil. The procedure is able to perform fully automatic determination of input parameters values. However, when only single test is used, several combinations of input parameters might get to the same result. Future research will be therefore focused on a combination of multiple measurements (e. g. from different depths) used during the optimization task. [ABSTRACT FROM AUTHOR]

During the biomass densification can be recognized various technological variables and also material parameters which significantly influences the final solid biofuels quality. The paper deals with the experimental research of the relationship between technological variables and material parameters during densification of acacia wood sawdust. The main goal of presented experimental research is to determine the relationship between compression pressure, pressing temperature and raw material moisture content and particle size during densification of acacia wood sawdust. Research findings presented in this paper are based on a realized experimental research which was done on Faculty of Mechanical Engineering STU in Bratislava. This experimental research was a logical result of and based on authors practical experience and wide theoretical analyses of selected variables influence. Described experimental research was realized by single-axis densification. This paper describes also the design of experiment (DOE) and evaluation methodology for this experimental plan in order to determine the influence of technological variables and material parameters on a final biofuels density which mainly represents the biofuels quality. This contribution discusses the analysis of experimental process, its individual steps and their subsequent DOE leading to the development of a mathematical model that will describe this process. The experimental findings presented here are showing the importance of mentioned variables and parameters during the densification process. [ABSTRACT FROM AUTHOR]

The econometrical time series are under investigation in this paper. The mathematical models describing connections between two time series in the form of VAR(p), Vector Autoregression, models are investigated. Their connection is confirmed by means of cointegration tests. If connected time series are described with some models (here the ARIMA, Autoregressive integrated moving average, models) with certain lag orders it’s assumed that maximal orders of ARIMA models are the upper limits for the orders of the VAR model. This point is investigated in the computational experiment. Non-linear terms are included in the VAR model. Such models could describe connections between some time series better. The ordinary least squares method is used to evaluate coefficients in the VAR equations. This method allows non-linear terms to be added into equations. Also there are two ways of ARIMA orders selection. The first one uses values of the information criteria (Akaike and Bayes critera), the second one is based on the correlation functions plots analysis. The maxima locations indicate maximal value of orders of the ARIMA model. Thus there are two ways to select VAR model orders. Both of them are tested. There wage index and money income index time series of the Dynamic series of macroeconomic statistics of the Russian Federation are investigated are investigated in the computational experiment. Investigating non-linear models the VAR model with high coefficient of determination is obtained. [ABSTRACT FROM AUTHOR]

The paper suggests the use of diagnostic features in the form of decomposition coefficients of biosignals statistical estimates in the normal range and in different types of pathologies obtained on the basis of a mathematical model in the form of a cyclic random process. As a criterion for choosing the necessary spectral coefficients of the biosignal decompositions in the Fourier basis set, was chosen the energy criterion. As diagnostic features, was used a such spectral coefficients that according to the Bessel inequality, contribute to the energy of the cardiosignal statistical estimation realization not less than 95% at their minimal number. In the work a software complex was developed for the processing and modeling of synchronously registered cardiosignals using models and methods of the theory of cyclic functional relationship. In general, the process of complex analysis of the electrocardiogram on the basis of the model in the form of a cyclic random process includes the following stages: 1) Segmentation; 2) Rhythm function evaluation; 3) Statistical processing ; 4) Statistical estimation normalization; 5) Statistical estimates decompositions. The complex analysis described above can be used in cardiac diagnostic systems in order to detect pathologies associated with changing the shape of the cardiac signal itself, which will serve as diagnostic information for the physician. [ABSTRACT FROM AUTHOR]

The article presents the methods of modeling two-phase flows. The widespread application of issues related to two-phase flows in industry encourages to familiarize with the methods of modeling this type of flows. The article presents basic mathematical models of two-phase liquid-solid flow on the example of sedimentation. In addition, numerical methods for simulating the sedimentation process are presented. Paper presents the possibility of using the Boltzmann method, the so-called LatticeBoltzmann methods in modeling multiphase systems. The LBM method is used primarily for modeling fluid dynamics, as an alternative to models based on the NavierStokes equation. A comparison of Euler-Euler method and Boltzmann method and the application of these methods to numerical modeling of two-phase flows is discussed Attention was paid to the advantages of the presented method and the great possibilities of accelerating calculations by their parallelization on modern graphic processors (GPU's). Experimental investigations of the sedimentation process in flow conditions were carried out and the theoretical parameters of the sedimentation efficiency were verified depending on the surface load (based on the experimental results). [ABSTRACT FROM AUTHOR]

The changes of the welfare of the Russian citizens are explored in the paper. The time diapason taken into account is: 2000 – 2018. The monthly wage index based on the Dynamic series of macroeconomic statistics of the Russian Federation data (2000-2018) has been explored. The mathematical models of the wage index of this time period have been presented. They are based on the ARIMA (p, d, q) models with p, q less than or equal to 5 (Autoregressive integrated moving average). Forecasts of these models are compared to predictions of the models with parameters p = 6 or q = 6. The constructed models have made better forecasts than the automatically fitted ARIMA ones with p, d less than 6. They have been compared using two metrics and also the Akaike and Bayes information criterion (AIC, BIC) has been considered. The seasonal factors of the wage index have been taken into account. It has been shown that the lags of 6 and 12 months are connected to the today wage index; maxima of this value are situated at the end of the year and in summer. It’s explained with the vacations which traditionally take place in summer and officially held vacations in January. [ABSTRACT FROM AUTHOR]

Study of wave motions fluid is one of the most important and complex problems of modern hydrodynamics. A mathematical model for dynamics of incompressible uniform viscous liquid stains in stratified medium is suggested. This model is described by the Navier-Stokes equations in the Boussinesq approximation. Stratification component of medium is saltiness. Bearing in mind that in such flows there are areas with large gradients of hydrodynamic parameters required methods should possess such properties as a high order of accuracy, minimum scheme dissipation and dispersion, as well as monotony. To solve the task, use the authors developed a method of splitting by physical factors, the method SMIF (Splitting on physical factors Method for Incompressible Fluid flows) possessing by the above-mentioned properties. Fore steps splitting scheme is considered. This paper will provide a brief description of the method SMIF. The test calculations and comparison with some theoretical, experimental data and calculations of other authors will be demonstrated. [ABSTRACT FROM AUTHOR]

The paper presents the calculation of the trajectory of an axisymmetric fracture propagation in an isotropic poroelastic medium considering fluid leakage and viscosity. The problem was solved using the extended finite element method (XFEM). It allows to obtain solutions containing a displacement jump with the help of discontinuous functions, and solutions near the crack tip with special asymptotic functions. This method can simulate the process of initiation and propagation of a crack in the direction that is determined from the analysis of the stress state in the vicinity of its tip. The simulation used an approach based on phantom knots and the cohesive fracture law which takes into account the existence of a zone of material softening in front of the crack. This means that it is not necessary to determine the critical stress intensity factor. The calculated trajectories are in agreement with experimental data obtained in other studies during the formation of fractures in blocks of polymethylmethacrylate. [ABSTRACT FROM AUTHOR]

The paper presents a mathematical model used to optimize a technological process to transform industrial engineering organization into an organization ecotehnologică. The mathematical model is composed of an objective function that takes into account three basic components (economic, social and environmental) process parameters, restrictions and criteria optimization parameters. The paper presents the economic component of the 36 variables of its social component with 39 variables and 46 environmental component variables and corresponding functions, taken in a particular case of industrial organization SC CONMAS SA. The experimental results of industrial organization in the three years 2012, 2013 and 2014 demonstrates its concern for sustained economic component but also for the environmental component. [ABSTRACT FROM AUTHOR]

The filtration is a hydrodynamic process which ensures the separation of a liquid - solid mixture. The paper presents a tridimensional mathematical model of the efficiency of the mechanical water filtering process. The mathematical model presented in this paper is based on a series of experimental values. The intake flow of the filter, the height and the nature of the filter layer are the variable parameters considered for conducting experiments and obtaining mathematical model. For transposition the physical model in mathematical model was used TableCurve 3D software. The research results have shown that the proposed model is able to predict the filtration efficiency of according to the parameters chosen for the experimental study (intake flow of the filter, the height and the nature of the filter layer). [ABSTRACT FROM AUTHOR]

This paper presents the evaluation and comparison test of a series of global geopotential models (GGM) using available terrestrial data over the territory of Montenegro. Using the model of Gravity Observation Combination 02S and 03S (GOCO02S and GOCO03S) with three different approaches (space-wise approach, time-wise approach, and direct approach) as well as the model of the Earth Gravitational Model 2008 (EGM08) and Earth Gravitational Model 1996 (EGM96) the anomalies of free air at 1293 points of gravimetric survey of Montenegro were determined; as well as the height anomalies at 46 points for which the discreet values of height anomalies are known. The discreet values of height anomalies were calculated as differences between orthometric heights, determined by high precision levelling and the ellipsoidal heights determined by the global positioning system (GPS/dh); and at the points of gravimetric survey of Montenegro, the free air anomalies related to the Geodetic Reference System 1980 (GRS80) and to the International Gravity Standardization Net 1971 (IGSN71) were determined. The data used in this paper are the data of gravimetric survey of former Socialistic Federative Republic of Yugoslavia, and the data of the height anomalies discreet values are data collected in March 2015 for further scientific research, particularly for geoid/quasigeoid determination for Montenegro. [ABSTRACT FROM AUTHOR]

The article tries to demonstrate that the actual structure of the marine dikes is inadequate both for protecting the sea shores against the marine currents erosion or for their own stability sake. Being a very permeable structure with big holes, the water currents flow almost freely through the dikes. This way, the dikes do not really act as a brake neither for the natural continuous near shore marine currents nor for the oscillating ones, resulting from the waves' oscillating water level. These phenomena explain the total inefficiency of the dikes built in Romania for protecting the Black Sea touristic sand beaches, where the erosion was in a continuous and aggressive progress even after the dikes' construction. The sand displacement in the foundation of the dikes explains also the very early failure, their fast settlement, for many dikes. Starting from very clear visual on the spot observations, the paper makes this demonstration scientifically, both through a mathematical modelling and through laboratory tests, made on a physical model at a reduced scale, designed, installed and measured in the "Wave Channel" of our Hydraulic Laboratory. Finally, the paper presents the authors' conception to improve that undesirable situation. [ABSTRACT FROM AUTHOR]

Concrete in some environments deteriorates and breaks down. Deterioration is caused from ion elusion both internally and externally. When the structure is in long-term contact with water the leaching might occur and deterioration process starts. Leaching is considered also to safety, durability and reliability of structures. It is really difficult to simulate it because of the long-term aspect. This paper is aimed at using a mathematical statistical method to investigate a relation between the selected deterioration parameters of concrete composites. The concrete specimens of standard recipe based on the Portland cement only and concrete composites with 10 wt. % replacement of cement by coal fly ash were exposed to water environment. The laboratory experiments focused on leaching processes proceeded in five cycles over a period of 90 days. Concentrations of basic leached-out components and pH values in concrete leachates have been chosen to determine the degree of deterioration. By X-Ray fluorescence (XRF) measured Si, Ca, Al, Fe, Mn and Cu concentrations in liquid phase were consequently evaluated considering mutual dependence (for both types of concrete samples). Investigation of leaching trend between the individual chemical elements from concrete composites with/without fly ash replacement was also analysed in the paper. [ABSTRACT FROM AUTHOR]

Temperatures recorded worldwide in 2015, in period January-November, they beaten the records, suggesting that this year was the warmest year in modern history. If no action is taken to reduce emissions of the greenhouse gas effect, the devastating consequences of climate change will continue. This paper presents a mathematical model for sizing of CHP plant based on biomass and natural gas. Biomass is used in cogeneration installation and the natural gas in peak installation. The mathematical model is useful for establishing the technical and economic efficiency of cogeneration solution, using the net present value criterion. Also the analysis uses, the criterion of value of cogeneration nominal thermal coefficient for the three areas of Romania: hot, cold, average. How, today, we are faced with mass deforestation of forests, reduction of arable land, floods and droughts prolonged, we ask ourselves what will happen in time with the plants that we build today. This paper presents two cases: two plants with different power outputs, high power (high available of biomass), low power (low available of biomass). [ABSTRACT FROM AUTHOR]

This paper presents the first phase of a study held in the context of the SECOSUD Phase II project, called "Conservation and equitable use of biological diversity in the SADC region (Southern African Development Community), which aims at promoting biodiversity conservation and sustainable economic development in the SADC [1]. The development goal of the Project is to contribute to stop biodiversity loss by supporting the development of conservation strategies. An important step in developing conservation of biodiversity requires a successful groundwater protection. Conservation of biodiversity depends on groundwater needs strategies that allows for the use of groundwater in a way that is compatible with the persistence of ecosystems in natural area, such as Limpopo Transfrontier Park, in the Southern African Region. Groundwater is a key element n the SADC region Groundwater is the primary source of water for people living in the SADC region, because it is used extensively throughout the southern African region, including the Limpopo River basin, supplying a large percentage of water for irrigation, rural water supply schemes and mining. The province has limited surface and ground water resources. Most of the water management areas are severely stressed and many people still do not have access to the accepted minimum supply of water. The goal of the strategy is to make sure that the water resources of protected areas are managed in an equitable manner so as to ensure the long-term sustainability of those resources, in order to the continue availability and security of supply of suitable quality water for all consumptive users and for the needs of the environment. Crystalline basement rock is distributed extensively throughout Africa and underlies large parts of the semi-arid Limpopo Province in South Africa. The development of crystalline basement aquifers as a reliable source of water supply is notoriously complex, and groundwater occurrence is spatially highly variable. Some of the greatest groundwater needs occur in the region and groundwater is the only dependable source of water for many users. The aim of the study is to provide an assessment of the actual groundwater monitoring network and in consideration of the growing demand for water, there is a need to understand the effects of planting on water rescouces to estimate crop water requirement for the focus area, as last step of the methodological strategy. This paper would outline a methodology on where to focuse future research. [ABSTRACT FROM AUTHOR]

This paper aims to modeling and simulation the behavior of massive earth retention structures saturated with water, the influence of pore water pressure and the negative effects of soil water saturation on them. Increased efforts in a state of earth retention structure usually leads to an increase in pore water pressure, as a direct result of the tendency to reduce the influence of pore volume loading. In soils with low water content or in cases when the increase rate of the pore water pressure in excess, this increase rate can be neglected. If the increase in pore water pressure is maximum corresponds to the case where the soil is fully saturated and drainage is stopped. The paper presents the assumptions on which the analysis is done and equilibrium equations are formulated for saturated porous media taking into account the interaction between the solid and liquid phase. Solving equilibrium equations with discrete finite element models will be made by formulating constitutive behavior laws of solid structure. Finally the results obtained from numerical simulations are analyzed and compared, highlighting the influence of pore water pressure on the behavior of the massive earth retention structures. The earth retention structures are particularly complex structures in terms of mathematical modeling due to different factors such as: * the diversity of the component materials having different physical and mechanical properties, with nonlinear behavior laws, consisting of water - solid biphasic nature of these materials which further complicates this problem. * the diversity of load diagrams. The nature of the materials that make up the body of massive earth structure requires that analyzes must be conducted according to the effective stress in the system. An analysis based on the total effort is not true for less permeable soil material. [ABSTRACT FROM AUTHOR]

The paper is focused on the analysis of dynamic effects of rail transport on the response of the railway base and embankment assuming the underground damping barriers. The dynamic analysis is based on numerical models using MIDAS GTS software. The paper presents the damping impact of two types of underground barriers (walls), which are located in different distance from dynamic load source and in material of barrier (concrete or gravel material). Contribution will present both the results of the maximum oscillation velocities and attenuation curves corresponding to the soil for assuming factors. In the end conclusions, focused on the qualitative and quantitative aspects of barriers impacts, have been formulated. The model analysis documented the positive effect of applied barrier resulted into the decrease of oscillation velocity. The higher effect was observed assuming concrete barrier -- the maximum oscillation velocity is reduced by 20 % comparing with the situation without barrier. [ABSTRACT FROM AUTHOR]

Computational modelling of hygrothermal performance of building materials has become very popular in recent decades as it is able to provide reliable results in a very short time. However, the accuracy of obtained results depends on various factors, the knowledge of material properties in particular. Even if many sophisticated experimental methods have been developed for that purpose, being able to provide reliable data, there is still one aspect which often remains ignored. According to the literature review, the major part of researchers do not consider changes of material parameters in time, e.g., due to weathering. In this paper, the long-term hygrothermal performance of two types of concrete is investigated by means of computational simulation. The results are achieved for three different locations in the Czech Republic. However, contrary to other researchers, reference and weather affected data are used and the related results are then compared and discussed. The obtained results reveal that weather affected materials may exhibit very different performance, either better or worse. Therefore, long-term changes of material properties due to weathering should be included in every long-term computational task that is supposed to provide relevant results. [ABSTRACT FROM AUTHOR]

The approach of Biotechnology Department of Mendeleev University of Chemical Technology of Russia covers integrated processing and the use of secondary byproducts in nature-like technologies for bioconversion into highly added value products with unique properties for sustainable development of the planet and lowering the negative industrial effect. This paper presents a mathematical model and solution strategy of S. cerevisiae single cell protein accumulation in deproteinized sunflower meal hydrolysates. Different biological models were tested with the experimental data. The temporal profiles of sugar and cell concentrations were modelled by a set of ordinary differential equations, which were solved using MATLAB software. Stannard model fitted the biomass production, Monod model - the deproteinized sunflower meal monosaccharides accumulation, formed during subsequent acid and enzymatic hydrolysis. The model was validated by the experimental data and the coherence between the model and experimental results demonstrates that the model is reasonable for prediction the dynamic behavior of the fermentation process. Model gives more information into the environmental conditions of the fermentation process and can be used for further development and scaling of the secondary plant by-products bioconversion into fodder for ruminants and monogastric animals. [ABSTRACT FROM AUTHOR]

The aim of the paper is determination of the temperature field which is caused by a heat flux in a thermosensitive (thermophysical parameters depending on temperature) layered medium which contains a foreign inclusion. The heat flux is concentrated at one of the boundary surfaces of the medium, the other boundary surface of which is thermally insulated. There exists ideal heat contact at the surfaces of the conjugated layers. In order to determine temperature regimes in such a medium, a nonlinear equation of heat conduction with nonlinear boundary conditions is used. In order to solve the nonlinear boundary value problem of heat conduction, we introduce a linearizing function which enables us to obtain a partially linearized differential equation and linear boundary conditions to determine this function. After the piecewise-linear approximation of temperature with respect to spatial coordinates is carry out, a linear differential equation with discontinuous coefficients in the linearizing function is obtained. An analytical-numerical solution of the obtained linear boundary value problem is found with the use of Fourier integral transformation which determines the linearizing function and enables us to obtain calculation formulae for calculation of temperature. Let us consider a linear temperature dependence of the coefficient of heat conductivity of the material for a two-layer medium with an inclusion, and let us make a comparative numerical analysis of the distribution of temperature for a linear (coefficient of heat conductivity of the materials of the layers is a constant quantity) and a nonlinear one (coefficient of heat conductivity of the materials of the layers is a linear variable with respect to temperature) models (materials of the layers are U12 and 08 steels). The temperature field for a layer with a through inclusion (material of the layer is Bk94-I ceramics, material of the inclusion is silver) have been calculated and analyzed. [ABSTRACT FROM AUTHOR]

Influences of earthquakes on nuclear power plants and their parts are studied in frame of nuclear safety. In the past, the authors have dealt with the effects of earthquakes and vibrations in the primary circuit. However, it cannot be omitted that the seismic influences can show up also on the secondary circuit. Turbines installed in secondary circuits of nuclear power plants are big and heavy machines. For example the turbine installed in JETE (Temelín Nuclear Power Station - Czech Republic) generates 1003MWe. It was made by Škoda Energo Company and it is the one of the biggest machines which rotates with 3000rpm (50Hz). Even the weight of the device itself causes the deformation on the rotor. Moreover, turbine rotors are very sensitive to lateral oscillations. These oscillations can be excited by the movement of the bearing, which is caused by the motion of the subsoil, due to seismicity. The paper introduces a mathematical model that describes the effects of lateral oscillations on the turbine rotor deformation. We present the method of calculation of dynamic deformation. One of the methods which can be used for calculation is the transfer matrix method. This model can be applied not only to nuclear power plants but generally to any large turbine rotor. [ABSTRACT FROM AUTHOR]

The paper presents a mathematical model designed to calculate the depth of the rut formed by a small-sized skidder on soft soils. The model bases on scientific research in the theory of off-the-road locomotion, completed with the authors' own theoretical developments. The model uses deformation modulus and bearing capacity as integral characteristics of strength and deformability of the soil. Moreover, because the deformation modulus of soft soils has a low value and is comparable to the normal stresses, the model uses a refined dependence for linking the soil deformation and the load parameters. Other physical and mechanical properties of the soil expressed in terms of its modulus, the expressions obtained as a result of the reference data approximation. The developed mathematical model uses refined formula to account the relationship of tire deflection of small-sized skidder and the soil deformation. The formula allows taking into account the fact that, ceteris paribus on soft soils deformation of the tire is smaller in value than the tire deformation on stronger soils. The model also takes into account the deviation of the direction of load resulting from the normal to the surface of soil and translational speed of the mover. This is achieved by introducing into the formulae for calculation of the bearing capacity correction factor on the direction of the load and the dynamic coefficient, calculated using the soil's rheological parameter in calculating the average pressure on the contact patch of soil with the mover. The model is implemented numerically in the software package Maple 2015. As a result of the calculated data approximation obtained a simplified model to estimate the depth formed on the soft soils under the influence of the small-sized skidder's mover. [ABSTRACT FROM AUTHOR]

Nowadays the conditions for admission to higher education institutions in Russia can allow centralizing the procedure for competitive selection of applicants across the country to increase the clarity and publicity of this process concerning applicants, as well as to reduce the universities expenses for the admission campaign organization. The federal information system for providing Unified State Exam and admission can become the heart of such centralization, but at the present time there are no algorithms for competitive selection. The research paper suggests a modification of the existing mathematical model for the organization of a centralized competition for higher educational institutions in Russia, which is a multi-criteria task of the objective function of higher educational institutions optimizing (the system of higher education generally), corresponding to enrolling the applicants with the highest score, and the target functions of entrants, consisting in the admission to the most interesting (top-priority) Programme of Study. To grade the applicants, we suggest the evaluation function modification, which includes a new term intended to gradate the entrants having the same scores for their entrance examinations and individual achievements as well. The research also suggests a heuristic iterative algorithm for solving the defined multi-criteria optimization problem, which is based on searching a solution for one particular university in the context of indicating a number of specialties and directions of preparation in the application of each enrollee. We have estimated the speed of the algorithm as logarithmic with the help of an especially designed program. The research shows that the algorithm is applicable for calculating the competitive situation nationwide over executing time. [ABSTRACT FROM AUTHOR]

With the steady rise of interest in blockchain and related technologies, researchers are making efforts to solve the remaining open questions in this field. One of the open problems is to achieve and maintain some desired characteristics of a private blockchain as far as the block generation rate is concerned. This problem is routed in statistical modeling. In this work, we will apply the results of participatory computing to build private blockchains and to resolve this issue. Private blockchains are important in cases when enforcing limited write access, while maintaining public readability and undeniability. One example could be the collection of publicly important data (e.g. environmental information, agricultural data) from a set of trusted sources (i.e. research stations). By applying participatory systems to blockchain technologies, there are a fixed number of participants in a group, who are in need for a private blockchain. Each participant has a number of clients, whom they provide service for. The participants use the resources of their clients to "build" the blockchain, i.e. the clients provide the proof-of-work required to append new blocks to the chain. In this paper we provide a mathematical model of this process and by statistical analysis we demonstrate how to achieve the desired block generation rate by evaluating its p.d.f. Our approach is based on modeling the random behavior of blockchains as well as the typical client behavior. [ABSTRACT FROM AUTHOR]

The paper presents model-in-the loop simulation results of the roadheader cutting speed control system. The roadheader is equipped with an 132kW induction motor supplied from the frequency inverter. The output frequency is calculated by a PI speed controller on the basis of speed error (signal difference between a reference signal from the load controller and the measured signal from the incremental speed encoder). The whole control system model (involving an inverter model, sensor model, induction motor linearized model, cutting head model and a PI controller) has been implemented using a Matlab/Simulink package. The induction motor equivalent circuit parameters have been calculated using a manufacturers data. Special attention has been paid to frequency rate limiter at the input of the frequency inverter. The load torque has been implemented using real signals recorded at the laboratory stand. As a controller setting selection criteria there has been used an integral criterion (Integral of Time multiplied by Absolute value of Error). The system stability has been checked using a Nyquist criterion. [ABSTRACT FROM AUTHOR]

The paper focuses on the results of mathematical modeling aimed to prove the possibility of application aluminum casing for Pulse Neutron Logging (PNL) tool. The simulation was carried out by the Monte Carlo method. A number of time decays for aluminum and steel cased PNL apparatus were calculated for carbonate rocks with different porosity. The model is represented by a rock with a 216 mm diameter well. 146 mm diameter steel column is cased in the well and has filled with fresh water inside. The PNL device is located along the well. Mathematical models of a pulsed neutron logging tool with an aluminum case were created. The obtained results showed the possibility of a significant increase in the count of the detected neutrons. The application of aluminum alloy made it possible to increase the total number of registered neutrons to + 80% and neutrons related to the well component to + 90%. The interesting fact that the increase of the useful signal on the far detector (60 cm) is within 75-77 percent and does not change much with the porosity change. This study showed the principal possibility of using an aluminum alloy as a PNL instrument case and it can be applied to devices that are already in use. [ABSTRACT FROM AUTHOR]

In this paper, one of the "problem zones" of mathematics is presented by computer and mathematical modeling. The study concerns the problem of learning of complex concept of the surface area mastering by students understanding. Students construct the multifaceted surfaces of Schwartz cylinder (or "boot") using computer and mathematical and adapt the most important generalized constructions to the actual position of mathematical knowledge concerning the analysis and the essence of the "problem zone" of surface area. The computer and mathematical design of the nonlinear dynamics of the manifestation of synergetic effects is developed step by step and dynamic invariants are revealed in the course of mastering the complex concept of the surface area. Namely, the means of the QT Creator environment are used for computer design of non-linear dynamics of functional parameters and technological constructs and students reveal the regularities and irregularities of lateral surface approximations of Schwartz cylinder. The study was carried out on the basis of triangulations of the lateral surface of the cylinder with regular and irregular limiting grinding by layered polyhedral complexes using computer and mathematical modeling tools. [ABSTRACT FROM AUTHOR]

Information regarding activity on the market provides valuable source for the future managerial decisions of each company. They are very important for achieving company strategic goals which represent part of a long-term strategic management concept of the company. Highly-valued information concerns especially the sales and the expenses development. Development of set company's values can be predicted to a certain extent using mathematical methods. Company can adequately respond to its future predicted state of variables which significantly affects company result. The aim of this paper is to perform sales development prediction for the chosen company with the use of a selected mathematical method which is time series analysis method. This prediction is modified by the amount of adjustment determined on the basis of verifying the accuracy of the sales prediction of the previous years. This method was chosen based on the obtained values of the coefficient of determination. Linear Regression Model with Logarithmic Transformations was chosen. [ABSTRACT FROM AUTHOR]

The paper deals with mathematical models developed at Centre ENET, VŠB -- Technical University of Ostrava. It is aimed at a model simulating blast furnace operation. The model has three parts. The first one calculates kinetic constants of iron raw materials reduction in blast furnace aggregate. The second used it for a simulation of iron oxides reduction. In the third part, the model simulates production process within the blast furnace feedstock contains of two-component burden. In the paper, the model is presented -- its objective, main calculations and conditions of simulation. [ABSTRACT FROM AUTHOR]

In relation with the development of renewable sources of energy investors suggest in many locations the construction of wind power plants. One of the regulating factors is the impacts of the wind power plants on the environment and human health. During long-term operation of wind power plants the habitat can be loaded with increased noise, which may affect the psychological well-being of citizens, and in some cases even it can physiological damage the hearing. The paper describes the specific parameters that are used in the evaluation of the impact of wind power plants on the exposed population. The influence is evaluated on the basis of a mathematical model of noise spreading from facility operations and practical terrain measurement of noise, taking into account the background noise at the site prior to the implementation plan. On a model example were evaluated potential effects on human health in the area and the expression of specific health injury symptoms, which may be caused with the operating of wind power plant. The paper also contains a relationship between dose and effect of damage to individual acts of public health. [ABSTRACT FROM AUTHOR]

The importance of soil loss by water erosion becomes more eminent with the ongoing climate change, where more extreme precipitations in middle Europe are anticipated. The amount of soil transported from the field plot can substantially differ according to the intensity of rill erosion. The capability of mathematical models to predict appearance of extreme soil erosion spots on arable land (rills and gullies) are addressed in this paper. Three surface runoff\erosion models were tested by comparing their outcomes with rills identified from orthophoto maps. Empirical methods are represented by Universal soil loss eq. (USLE). The equation is a simple method of the long term modeling of the sediment yield. Limitations of this method are in estimating soil loss from rainfall episodes and application of this equation in areas with concentrated flow is debatable. Second tool used is physically based model SMODERP which is being developed on CTU Prague since 1990s. Soil characteristics are based on Czech soil taxonomy system. The model SMODERP is excellent tool for modeling of sheet and concentrated surface runoff. Hydrological part of the model includes the processes of infiltration (Phillips equation), sheet surface runoff (Kinematic wave based equation), rill runoff, surface retention. Third tested modeling approach is based on Erosion-3D simulation model, developed at TU Freiberg (Germany). Erosion-3D is physically based and fully distributed rainfall- runoff model allowing calculation of transported sediment. The model can be run for single event, repeated events or sequence of events and the outputs include characteristics of runoff and soil transported in three particle size fractions. The soil input parameters are based on German standard of soil classification KA4. The uncertainties in inputs strongly influence the absolute values of soil erosion, but spatial distribution of netto erosion can be useful in identification of rill erosion appearance. The paper describes validation and application of models at the experimental field plot near Benesov (Central Bohemia, Czech Republic) in 2010. Airborne photographs of the field plot with apparent consequences of a heavy rainstorm event were used to visually derive the pattern of erosion rills and ephemeral gullies which were used for the main comparison. Standardized plots (22.1 m in length, 9 % slope) for long term monitoring of erosion processes have been installed on this experimental field. Outflow from the plots and precipitation are automatically continuously measured during each natural rainfall event. The soil concentration in outflow and the volume of transported sediment is determined from samples in laboratory. Data from experimental plots can be used for validation of the model's input parameters. [ABSTRACT FROM AUTHOR]

The paper presents a study into the potential of aerial measurement of NO pollutants for predictive mathematical modelling of NO distribution including the impact of earth surface topography. The paper describes a method of data collection and processing for dynamic modelling. The results consist of a description of the mathematical modelling methodology used and of a visualisation of the NO mass fraction isoplane [ABSTRACT FROM AUTHOR]

In the processing the results of measurements in geodetic practices typically uses the Method of Least Squares (LSM). The mathematical basis of the is worked out and certainly has their strengths because a fulfillment of normality measured surveying data files, this method results in to a the most reliable estimate of the unknown parameters. Otherwise, it is necessary in processing of surveying measurements to use alternative solutions that are robust as the estimation method and the method of linear programming. From the methods of linear programming is known for professional public simplex method. It is an iterative computational procedure in linear programming is used to find the optimal solution. The present paper deals with the application of simplex method on the example of the regression line. Of minimization problem with this method solves the standard programming tabular form, line and column rearrangement operations aimed at reducing the original table to the the canonical form. In the paper is to compare numerically more simple, more stable and more efficient ways of dealing with the problem of linear programming with matrix relations. [ABSTRACT FROM AUTHOR]

This article presents issues related to model building for tasks of forming and modifying a custom user interface. We describe the possibility of using neural network methods to process the input data and classify the categories of user interfaces. The investigated task is solved by modeling the structure of an artificial neural network based on a multilayer perceptron. The preparation of a training data set and the use of this set for the training of neural network are provided. Input layer is considered a distributor of the signals from the external actions of network users with their interfaces. The output layer is considered a generator of some structural parameters of the user interface. Using the obtained parameters of the neural network the mathematical model constructed and analyzed for solving the above problem. The resulting data tested for various input data sets that were not used for training the network. In this paper, we investigate the possibility of applying the designed model for processing information needs of users, analysis and accumulation of the various parameters of user interface, and therefore applicability of this model for forming the most suitable solutions for users. [ABSTRACT FROM AUTHOR]

The problem of a vortex pair motion under a free surface is considered. It is known (Barker S.J. & Crow S.C., 1977) that the vortices fly apart with respect to each other in the horizontal direction. The domain of computation will be on the half-plane with the symmetry condition on one of the vertical boundaries. Previously was received (Gushchin V.A. & Konshin V.N, 1992), that for the correct mathematical modeling of an unsteady thick layer of homogeneous incompressible liquid flow through an obstacle, it is necessary to solve a complete system of Navier-Stokes equations. The authors suggested a second-order CABARET scheme in a Lagrangian grid with nodes fixed in the horizontal direction. A transition is made to new curvilinear coordinates, such that the nodes are uniformly distributed in the vertical direction. According to the methodology ([15] Goloviznin V.M. et al., 2013) of the CABARET scheme for the new system of equations in the divergent form, a conservative difference scheme is proposed. Also, along with conservative variables, we derive the characteristic form of the equations for local Riemann invariants. Splitting by physical factors for the motion equations is used. The aim of the paper is to construct a new difference scheme for the problems of motion of an incompressible fluid. Nonlinear nonstationary phenomena are significant in a wide range of flow parameters in the presence of a free surface. [ABSTRACT FROM AUTHOR]

The paper deals with the study of Powered roof support analysis, taking into account the interaction with surrounding rocks. In this respect, an analytical model of kinematics and load of the shield, a differential model of the shield-rock system equivalent stiffness and a Fuzzy logic based analysis of the parameters variation are presented. In the first two models, the classical approach of shield mechanics, the loading scheme was modified by taking into account the horizontal force acting between the roof and the canopy which was presumed to be a frictional force, and the capsule force according to maximal yield force of the legs are determined for different values of the location of normal force on the canopy. Also, a differential equation has been derived, in order to obtain the time-dependent variation of the shield reaction taking into account the roof convergence, and the operation of the safety valve. The Fuzzy logic based method is used to derive the response surfaces/curves representing the dependence between basic parameters of the shield, as the initial setting pressure, and the stiffness on the response metric, i.e. the convergence and load increase during a working cycle. [ABSTRACT FROM AUTHOR]

The problem of visualization of fires is relevant to the design of emergency situation simulators for industrial facilities involving a risk of fire or explosion. The effectiveness of a simulator depends on the accuracy of animation (visualization) used in this simulator. The present paper aims to build a mathematical model of fire spread at industrial facilities with regard to the associated processes of smoke generation, release of toxic combustion products and their influence on physical condition of an individual. The model is based on the results of the analysis of fire hazard properties of materials, mechanisms of fire occurrence, their distribution among the objects and the elimination of fires using fire-fighting equipment. The developed mathematical model is intended for application in adaptive simulators (ASs) created using virtual and augmented reality technologies. The developed fire spread algorithm was used as the basis for software implementation of the mathematical model in the AS, using Unity 3D development environment. The results of the study were used to find the fire spread visualization parameters in the AS through simulated emergencies occurring in the manufacture of dyes and pigments at PJSC "Pigment" (Tambov, Russia). [ABSTRACT FROM AUTHOR]

The aim of this work is to build a mathematical model of the dynamics and mutual influence of the population and environmental factors - pollution of the atmosphere and surface water bodies - on an urbanized territory. The paper proposes a simulation model of dynamics and interaction of external and internal directions in biosphere-compatible city activities. The external direction of city's activities is removal of resources from the Biosphere and emission of waste polluting water, air and soil into it. The internal direction is the impact on the population: environmental state, health assessment, life expectancy, human potential. The method of forecasting the ecological and demographic situation of an urbanized territory is constructed using a relatively simple, non-linear, with variable coefficients, mathematical model that reflects the interaction of several subsystems: population, pollution of the atmosphere and water bodies. [ABSTRACT FROM AUTHOR]

The paper presents the factors affecting the performance of a mining company, identified and classified into two categories: internal and external factors. Further, the paper evaluates the external factors affecting the activity of a mining company, and identifies possible correlations between factors or group of factors and the performance indicators of the mining company. These correlations are validated in time by the evolution of the pair: external factor - indicator value, or are object of simulations -- in order to identify possible scenarios of external factors. These simulations are aimed to upgrading the organizational processes so the resulted processes to present an optimal behavior in the simulated situations. Also, we need to note that this method to evaluate the influence of internal and external factors on the entire quality and performance level from the company is done in fuzzy logic. [ABSTRACT FROM AUTHOR]

Gozna and Secu reservoirs from Semenic Mountains are water management works which are used to obtain electric energy, source of drinking water for Resita and recreational areas. In this paper the status of eutrophication on both reservoirs is analysed based on water samples collected over 9 years (2001 - 2009). We developed a mathematical model based on multiple correlations between the most important eutrophication parameters. Water quality parameters from these reservoirs were: water transparency, temperature, pH, dissolved oxygen, CBO5, CCOMn/O2, total nitrogen, total phosphorous, density and biomass. From a trophic point of view, the two reservoirs fall into mesotrophic category with eutrophication tendency, as a result of human activity in the area. [ABSTRACT FROM AUTHOR]

The paper deals with the comparison of experimentally measured temperature of the hot gases within the enclosed area under fire and with numerical estimated values based on selected empirical methods. There are a variety of methods to estimate the temperature of the hot gases with respect to time in an enclosed space. Most predictive method take in account a single-zone area in which the temperature is modelled as uniform throughout the area at same time. Manually assembled scale model was made for the purposes of experimental fire modelling in an enclosed space with using of dimensional dimensionless groups. The spruce wood as a fuel source within the model was used to simulate different fire load. The purpose of comparison the experimentally measured values and numerically predicted temperature value is verifying of accuracy and relevance of selected empirical assessment methods and their applicability to the building scale models. [ABSTRACT FROM AUTHOR]

Paper presents a mathematical model and an objective function used in a machine building plant transformation into a eco-technological organization. Mathematical model consists in an objective function that considered three components (economic, social and environment), technological process variable, variables restrictions and optimisation criteria. It refers to social component importance with 39 time variables and corresponding objective function in a case of Romanian plant during 2012, 2013, 2014 years. [ABSTRACT FROM AUTHOR]

Paper presents a mathematical model and an objective function used in a machine building plant transformation into a eco-technological organization. Mathematical model consists in an objective function that considered three components (economic, social and environment), technological process variable, variables restrictions and optimisation criteria. It refers to environmental component importance with 46 time variables and corresponding objective function in a case of Romanian plant during 2012, 2013, 2014 years. [ABSTRACT FROM AUTHOR]

In the present paper attempt was done to examine the impact of the number of observed satellites, from various Global Navigation Satellite Systems (GNSS) on the results of measurements performed using RTK technique (Real Time Kinematic). The research was performed in static mode at four stations with the use of various combinations of four currently available systems: GPS, GLONASS, BDS and GALILEO. The coexistence of four different independent Global Navigation Satellite Systems gives the user wide possibilities of use Multi-GNSS applications if only the receiver of satellite signals has the technical capabilities. Using the Multi-GNSS increases the number of observed satellites, which results in the increase in the number of observed signals and frequencies. In turn, the increase in the number of observed signals and frequencies (observation) has a direct impact on the growth of availability and range of the used measurement method, it also gives a chance, that the results will be characterized by higher reliability and accuracy. However, for this to be possible, the user must be equipped with a dual-system receiver, and Multi-GNSS applications must properly take into account in solving inter alia, aspects such as, different reference systems, different time systems, different satellite orbits for each of the used systems. Only then measurements using satellites from various positioning and navigation systems will give better results in comparison to a situation when only one GPS system is used. In the work multiple, daily research measurements using multi-satellite receivers, Trimble R10 GNSS System, were made in four combinations: GPS, GPS+GLONASS, GPS+GLONASS+BDS, GPS+GLONASS+BDS+GALILEO. To compare the accuracy of position determination in various combinations, from the coordinates obtained from the measurements the coordinates of the reference checkpoint were subtracted. On this basis it has been shown empirically, that a greater number of observed satellites can significantly improve the accuracy and reliability of satellite measurements. It has been proven also, that it also affects the improvement of the observation conditions defined by DOP parameters (Dilution of Precision). The research has shown that the increase of the number of the observed satellites under certain conditions can lead to the reduction in errors of determined coordinates up to about 30%. [ABSTRACT FROM AUTHOR]