Mathematical Simulation Methods Research Articles

Numerical analysis of thin-walled round-ended concrete-filled steel tubular short columns including local buckling effects

The behavior of thin-walled round-ended concrete-filled steel tubular (RECFST) short columns loaded axially is characterized by the local-buckling of the flat steel walls and the concrete confinement exerted by the round-ended steel walls. A numerical modeling method implementing fiber analysis is presented in this paper for the determination of the behavior of short thin-walled RECFST columns subjected to axial loads. The mathematical simulation method explicitly incorporates the progressive local buckling of the flat steel walls as well as concrete confinement induced by the round-ended tube walls. A new constitutive model is developed by analyzing the available test results for determining the lateral pressures on the concrete confined by the round-ended tube walls. A coefficient of strength degradation is provided to quantify the residual strength of the encased concrete. The independent test results are utilized to assess the accuracy of the computational modeling scheme. Comparative investigations are carried out to evaluate the accuracy of the numerical models of RECFST columns presented by other investigators. The computer modeling program designed is utilized to quantify the structural responses of thin-walled RECFST composite columns subjected to the variations of material and geometric parameters. A design equation is given for designing thin-walled RECFST columns considering local buckling and concrete confinement effects. The applicability of the current design standards for circular and rectangular CFST columns to RECFST columns is assessed by utilizing experimental data. It is found that the current design codes need to be modified to be used to design RECFST thin-walled columns. The proposed computer simulation program and design equation are demonstrated to accurately yield the performance of RECFST columns under axial loading.

Synthesis of an Interference-Resistant Space-Time Filter for High-Precision Measurements of Navigation Parameters According to the Signals of Global Navigation Satellite Systems

We study the problems of serviceability of contemporary high-precision terminals of global navigation satellite systems under the conditions of jamming and spoofing interferences. The application of digital antenna arrays with algorithms of space-time signal processing of the signals can be regarded as a solution of the problem of low interference resistance. We describe well-known, most studied, and currently applied algorithms of space-time signal processing. We also formulate the causes that do not enable one to use well-known algorithms in high-precision terminals of satellite systems of global navigation. We propose an algorithm of space-time signal processing based on a space-time filter of finite length with a theoretically justified requirement of Hermitian symmetry for the matrix impulse response. The proposed algorithm guarantees the absence of distortions of signals under any signal and interference conditions. In this case, the impulse response of the space-time filter is computed according to the criterion of optimal suppression of the interference. The characteristics of the proposed space-time filter and other algorithms of space-time signal processing are investigated. For this purpose, we apply the method of mathematical simulation with random search of numerous parameters of signals and interferences (directions to signals, directions to numerous interferences, and to their reflections, remoteness of the reflectors of interferences, the phases of reflections, and the levels of interferences and reflections, etc.). The results of simulations are presented in the form of the distribution functions of the signal-to-interference ratios at the output of the algorithms of space-time signal processing and the distribution functions of the phase and signal-time biases. The obtained dependences substantiate the absence of the phase and signal-time biases in the space-time filter for any signal and interference conditions with interference multipath. It is shown that the space-time filter guarantees a higher interference resistance than the compensating algorithms of space-time signal processing.

ДОСЛІДЖЕННЯ ПОКАЗНИКА ЕФЕКТИВНОСТІ ЕКСПЛУАТАЦІЇ ЗАСОБІВ ВИМІРЮВАЛЬНОЇ ТЕХНІКИ МЕТОДОМ КОМПʼЮТЕРНОГО МОДЕЛЮВАННЯ

The operational efficiency of measuring equipment (ME) is important in determining the cost of maintaining ME. To characterize the operational efficiency of the ME, an efficiency indicator has been introduced, an increase of which will reduce costs caused by the release of defective products due to the use of ME with unreliable indications. Over time, the ME parameters change under the influence of external factors and the ME aging processes inevitably occur, as a result of which the parameters of the ME metrological service system change. Therefore, in the general case, the parameters of the metrological maintenance system of ME should be considered as random variables. Accordingly, the efficiency indicator of measuring instruments is also a random variable, for the determination of which it is advisable to apply the methods of mathematical statistics and computer simulation. The performance indicator depends on the parameters of the metrological maintenance ME system, such as the calibration interval, the time spent by the ME on metrological maintenance, and the likelihood of ME failure-free operation. As a random variable, the efficiency indicator has a certain distribution function. To determine the distribution function of the efficiency indicator and the corresponding statistical characteristics, a computer simulation method was used. A study was made of the influence on the indicator of the effectiveness of the parameters of the metrological maintenance system ME (interesting interval, the failure rate of ME). The value of the verification interval and the failure rate of MEs varied over a wide range typical of real production. The time spent by ME on metrological services is considered as a random variable with a normal distribution law. To obtain random numbers with a normal distribution law, the Box-Muller method is used. After modeling, the statistical processing of the obtained results was done. It is shown that in real production, the efficiency indicator has a normal distribution law and the value of the efficiency indicator with an increase in the calibration interval does not practically change.

Modern status and ways of development of round billet production technology by steel continuous casting

Production of round billets by steel continuous casting, widely used for manufacturing seamless pipes, railway wheels and tyres, quality long rolled products etc., is widely spread in the world steel industry. Constant search for improved design of CCM takes place, separate parts of existing machines are being perfected. An analysis of collected in the world practice experience of solving problems, related to production of round continuously casted billets, enables to choose proper technical solutions for each particular situation, to determine rational parameters of technology. History of development of round continuously casted billets production technology considered. Data on their modern producers presented. Peculiarities of steel continuous casting technology, as well as reasons of defects of round continuously casted billets have been discussed. Classification of basic kinds of cracks of round continuously casted billet presented. Basic problems during production of round continuously casted billets relate to ovality formation, mainly because of unevenness of heat-away in the mold. The increased ovality can lead to formation of internal and external cracks. Ways of solving problems of defects formation and ways of round continuously casted billet technology perfection summarized. Application of methods of mathematical simulation for a technology, which enables to produce defectless billets considered. It was shown, that basic measures to decrease number of billet defects, relate to setting rational parameters of temperature-speed mode, transfer to internal mold profile, corresponding to the billet shrinkage. Another measure is elimination of uneven impact of the liquid metal stream on the solidifying shell in the area of small and big radius. A perspective direction of round continuously casted billets production technology perfection is application of soft reduction methods and electromagnetic stirring of the liquid metal.

Car integral performance index simulation

Introduction . The paper is devoted to the comparison and evaluation of the quality of a car using the method of mathematical simulation of the integral performance index. The work objectives were to develop a mathematical modeling technique for the integral performance index, to draw up a step sequence of quality assessment, to analyze most common brands of passenger cars on the domestic market, to sum up and validate the result obtained. Materials and Methods . The sequence of simulating the integral performance index is proposed. Numerical modeling of the integral performance index is carried out on the example of six most common brands of passenger cars on the domestic market. Results . A method of modeling the integral performance index is developed. A step sequence of the analysis is described. An additive form of determining the integral performance index which provides combining single, unrelated quality indices into a complex indicator in the process of comparison is proposed. Discussion and Conclusions . The proposals presented can be used in the process of assessing and diagnosing the competitiveness of not only cars, but also of other products with a large set of independent quality indicators.

Justification, development of new technology and design for drying seeds of desert fodder plants

Proposals for the development of highly efficient new resource and energy-saving technologies and designs for seed drying are substantiated in the paper-based on theoretical research and scientific results. The developed new improved design of a vacuum drying unit with a heat transfer fluid and a heat accumulator for drying seeds of desert fodder plants, a diagram of the energy storage process, an irradiation scheme using heat waves of a flat layer are substantiated and presented.The positive effect of external physical fields on drying processes is substantiated and determined by mathematical simulation and experimental methods. Design basics of drying equipment of desert fodder plant seeds are developed in analytical solutions based on numerical values of key parameters. Extensive information is provided on the previously obtained results of an analytical study and computer implementation of the developed advanced mathematical models; the solution to the problem of seed drying in an analytical form for non-stationary and stationary problems of the known system of A.V. Lykov differential equations are given.

Application of Neural Networks in the Problem of Quantitative Analysis of Air Composition

Purpose of reseach is to develop a method for generating training data to enable the use of artificial neural networks (ANN) method in gas analyzer systems. The problem of increasing the accuracy of separate determination of gas concentrations in multicomponent mixtures under conditions of environmental parameters changes is considered. It is proposed to increase the accuracy of determining target gas concentrations by using the ANN method for joint processing of sensor signals.Methods: Training data for the neural network were generated using numerical experiments and mathematical simulation methods. To assess the accuracy of training, the standard deviation (SD) was used and the relative error was calculated. ANN training and research were conducted in the MATLAB environment (the Neural Networks Toolbox application). When developing mathematical models of gas sensors, the theory of electrical circuits, electronic theory of chemisorption and the adsorption theory of heterogeneous catalysis were applied.Results: A method for generating training data sets using mathematical models of gas sensors is described. The proposed training method has been tested on a specific task, in particular, a decision-making device based on ANN for a four-component gas analyzer has been developed. The efficiency of using neural networks for tuning out from the mutual cross-sensitivity of sensors was evaluated.Conclusion: A method for generating training data using simulation models is proposed, which allows automazing the process of training, research, choosing the architecture and structure of ANN and their testing. The method was tested. Based on the analysis of the obtained errors, conclusions are made about the efficiency of using neural networks to reduce errors caused by cross sensitivity at different concentrations of the main and interfering gases.

ПОВЫШЕНИЕ ТОЧНОСТИ КРАТКОСРОЧНОГО ПРОГНОЗИРОВАНИЯ ЭЛЕКТРОПОТРЕБЛЕНИЯ ГРУПП ТОЧЕК ПОСТАВКИ ЭЛЕКТРОЭНЕРГИИ ГАРАНТИРУЮЩИХ ПОСТАВЩИКОВ ВТОРОГО УРОВНЯ

Актуальность обусловлена необходимостью повышения точности краткосрочного прогнозирования электропотребления групп точек поставки электроэнергии гарантирующих поставщиков второго уровня. Результаты данного прогноза используются системным оператором при формировании диспетчерского графика выработки и потребления электроэнергии. Ошибки прогнозирования, как правило, приводят к увеличению расхода первичных энергоресурсов на выработку электроэнергии за счет необоснованных пусков и остановов генерирующего оборудования, а также к увеличению потерь при передаче электроэнергии, вследствие выбора неоптимальной схемы электрических сетей. Так как потребление электроэнергии зависит от множества факторов, задача краткосрочного прогнозирования данного временного ряда является слабоформализуемой. В данных условиях традиционные средства математической статистики и имитационного моделирования не позволяют строить адекватные прогнозные модели. До недавнего времени единственным адекватным методом прогнозирования потребления электроэнергии был метод экспертных оценок. В настоящее время для краткосрочного прогнозирования электропотребления энергосистемы региона страны или группы точек поставки электроэнергии гарантирующего поставщика первого уровня все большее применение находят инструменты нейронных сетей. Однако разработанные модели мало пригодны для прогнозирования почасового потребления электрической энергии групп точек поставки электроэнергии гарантирующих поставщиков второго уровня. Краткосрочное прогнозирование потребления электроэнергии данных объектов осложнено тем, что, помимо стандартных временных и метеорологических факторов, необходимо учитывать надежность электросетевого оборудования 6–110 кВ, режим работы потребителей электрической энергии с мощностью 670–10000 кВт, а также наличие центрального отопления и горячего (холодного) водоснабжения в населенном пункте, питающемся от группы точек поставки электроэнергии. Для них остается открытым вопрос выбора оптимальной архитектуры и конфигурации нейросетевой модели, а также алгоритма ее обучения, при использовании которых достигается требуемая точность прогнозирования. Цель: повышение точности краткосрочного прогнозирования электропотребления групп точек поставки электроэнергии гарантирующего поставщика второго уровня с помощью инструментов нейронных сетей и глубокого машинного обучения. Методы: методы корреляционного и факторного анализа, теории искусственных нейронных сетей и машинного обучения. Программная реализация теоретических выкладок выполнена с помощью библиотеки глубокого машинного обучения Tensor flow Keras на языке программирования Python 3.6. Результаты. Разработан нейросетевой алгоритм краткосрочного прогнозирования электропотребления групп точек поставки электроэнергии гарантирующего поставщика второго уровня с адаптивными в процессе обучения параметрами скорости обучения и момента инерции. Выполнена программная реализация данного алгоритма в библиотеке глубокого машинного обучения Tensor flow Keras. Использование данной искусственной нейронной сети позволило снизить среднемесячную относительную ошибку прогнозирования на 5,14 %.

Sociodemographic management indicators of the state of the economy (a case study of Russian statistics)

PurposeThe purpose of this research is to relate the pattern of economic growth with demographic data based on the natural population changes.Design/methodology/approachThe methodological foundation of this research consists in the structural and functional approach to the comprehension of the social system, methods of mathematical simulation of the dynamics of expansion and extension of the ecological niche of population and methodologies that are currently used for calculation of gross domestic product (GDP).FindingsThe research finding consists in the development of the theory of social evolution in the form of horizontal and vertical social differentiation, which is conditional upon the growing production of the excess product, which leads to the simulation of relation between the natural population changes and the production of GDP, expanding the boundaries of the ecological niche.Research limitations/implicationsThe relevance of the problem under study is driven by the need for theoretic interpretation of interrelation between the pattern of economic growth and demographic data based on the natural population changes.Originality/valueThe research leads us to the conclusion that there is a functional (for closed societies) and correlative (for open societies) relationship between the GDP growth and natural population changes with the property that the positive or negative population growth depends on the quantity of the total consumed costs (TCC) and its critical values.

A Simulation and Optimization Study of the Swirling Nozzle for Eccentric Flow Fields of Round Molds

In continuous casting, the nozzle position may deviate from the center under actual operating conditions, which may cause periodic fluctuation of the steel-slag interface and easily lead to slag entrapment and gas absorption. Swirling nozzles can reduce these negative effects. A mathematical simulation method based on a round mold of steel components with a 600 mm diameter is applied to study the flow field of molten steel in a mold. The swirling nozzle is optimized through the establishment of a fluid dynamics model. Meanwhile, a 1:2 hydraulic model is established for validation experiments. The results show that, when the submerged entry nozzle (SEN) is eccentric in the mold, it results in serious bias flow, increasing the drift index in the mold up to 0.46 at the eccentric distance of 50 mm. The impact depth of liquid steel and turbulent kinetic energy can be decreased by increasing the rotation angle of the nozzle. The nozzle with one bottom hole, which significantly decreases the bottom pressure and turbulent kinetic energy, greatly weakens the scour on nozzle and surface fluctuation. In the eccentric casting condition, using the optimized swirling nozzle that employs a 5-fractional structure, in which the rotation angle of 4 side holes is 30° and there is one bottom outlet, can effectively restrain bias flow and reduce the drift index to 0.28, a decline of more than 39%.

SIMULATION MODELING OF PARAMETERS OF FUNCTIONING OF RAILWAY PROJECTS

The speed of communication on any route, directly and indirectly through the function of redistribution of traffic volumes, causes an increase in the number of movements, traffic volumes, transport work, in the network of the appropriate type, at the same time the values of the medium system coefficient of passenger capacity use and the number of vehicles may vary both in the direction of the increase and vice versa. The results of the calculations of the basic parameters of the functioning of intercity passenger route systems for various values of the speed of communication on intercity railway routes established the appropriate mathematical model for determining the parameters of this passenger communication. The conducted analysis of simulation methods has determined the possibility of using for the determination of quantitative parameters for changing the basic indicators of the operation of the system of intercity passenger route methods of mathematical and computer simulation. The results of the work determined the basic indicators of the functioning of the system of intercity passenger route transportation. These indicators include: the number of movements in the network; volume of transportation; transfer ratio; transport work; average distance of the route; average distance of the network ride; medium coefficient of passenger capacity use; required number of buses / cars. According to the analysis of the methods and models of calculations of the basic indicators of the functioning of the system of intercity passenger traffic, it was assumed that the change in the quantitative characteristics of the parameters entering into the system or the quantitative characteristics of its elements may lead to a change in the quantitative indicators of the functioning of the system itself or its individual elements. Keywords: transport system, intercity passenger transport route, basic parameters of transportation, efficien-cy, model.

Research Methodology for Microwave-Convective Processing of Grain

Studying the effect of microwave fields on the intensification of heat and moisture exchange processes in a granular layer is a rather complicated task, which cannot be effectively solved without an adequate research methodology. In presented materials, a system of principles and approaches for studying processes of microwave-convective grain treatment has been discussed. Based on the explicitly defined process target, functional-physical analysis has been performed that made it possible to specify the most essential factors of process. Morphological analysis of processes shall be performed in several stages. At each stage, targets of process have to be set by excluding combinations of factors that have no reason to be considered at this particular stage of process development. Application of mathematical simulation methods is advisable for selection of optimal options.

Simulation and Analysis of a Quadrotor UAV while Landing.

Unmanned aerial vehicles are widely used in military and civilian fields in recent years. Quadrotor Unmanned Aerial Vehicles (UAV) have high advantage among other UAV’s, in different categories, due to their ability to hover, and Vertical Take-Off and Landing (VTOL) capability. The mathematical simulation method can be adopted for analysis of UAV. The simulation method can reduce the flight period, cost and risk and improve its performance while Vertical take-off and landing (VTOL). While landing of UAV, the kinetic energy of vehicle is absorbed by UAV frame resulting in high stress concentration. The stresses are also produced in other parts of the UAV. The effect of the landing loads and stresses on the airframe of the quadrotor unmanned air vehicle must be completely understood and the UAV must be designed accordingly in order not to damage during landing.These stresses can be analyzed by simulation method to ensure the sustainability of UAV structure. This work includes structural and frequency analysis for Quadrotor UAV chassis.

MATHEMATICAL DESIGN OF POLYCOMPONENT DRINKS WITH A BALANCED NUTRIENT COMPOSITION

Based on the principles of food combinatorics using the methods of mathematical and computer simulation, formulations of polycomponent drinks based on dairy and vegetable raw materials were developed. The drinks were cow's milk, bananas, spinach and pumpkin were used as plant material and chia seeds were used as a source of unsaturated fatty acids. Using mathematical planning, the criterion equations for beverages characterizing the maximum content of basic nutrients have been formed. Computer simulation of beverage recipes was performed in Excel Solver in a Microsoft Excel spreadsheet, which formalized qualitative and quantitative indicators of balanced nutrients. In computer-aided design, optimization for each selected indicator was used by paired with the recommended nutrient content of FAO / WHO. Formulations of pumpkin, spinach and banana beverages were obtained in which the content of basic nutrients was 18,889 g, 17,664 g and 21,329 g per 100 g, respectively. Analysis of the chemical composition showed that the ratio of proteins: fats: carbohydrates is 1: 1.45: 3.03 for the drink "Pumpkin", 1: 1.34: 2.57 for the drink "Spinach" and 1: 1.5: 4 , 27 for the Banana drink. The ALST method determines the storage conditions of developed beverages, taking into account changes in sensory and microbiological parameters. Determination of optimal storage conditions by estimation of changes in organoleptic parameters makes it possible to state that the developed beverages will be competitive in the establishments of the restaurant industry of Ukraine. A study of changes in the microbiota of finished beverages within 4 hours at (4 ± 2) ° C in a closed glass container showed that, in the presence of conditionally pathogenic microorganisms, the beverages meet the current regulatory requirements. The integrated approach to the production of multicomponent beverages can be used by any market operator to produce not only beverages but also various food products.

MATHEMATICAL AND COMPUTER MODELLING REGULATORY MECHANISMS FOR PROGRAMMED CELL DEATH (APOPTOSIS)

The system for removing needless cells (programmed cell death apoptosis) is important in coordination of structural-functional organisation of large number of cells in an organism. Discovery of cells suicide phenomenon has allowed revising old notions about regulation mechanisms of cellular homeostasis and importance of this mechanisms disturbance during development of large number of diseases including cancer, auto-immune diseases and infection processes. Intuitive understanding activity of the regulatory system connected by means of complex interaction mechanisms between positive and negative feedback loops is very difficult. Here it is necessary formal mathematical methods and computer tools for modelling corresponding regulatory mechanisms. This work deals with some results of the quantitative analysis of simplest regulatory mechanisms for apoptosis process based on the methods for mathematical modeling and computer simulation.

VORTEX DEVICES OF THE DIESEL AIR SUPPLY SYSTEM: MATHEMATICAL MODEL OF AERODYNAMIC PROCESSES

Introduction. The calculation of effective indicators of the vortex ejector used in the diesel air supply system is a pressing task as it allows significantly reducing time for determination of rational design parameters at the design stage. One of the modifications of the particle dynamics method is a promising direction, allowing with high physical adequacy, “from the first principles,” to model aerodynamic processes in vortex devices. Therefore, the purpose of the paper is to develop a mathematical model of a vortex ejector.Materials and methods. The paper discussed a method of the mathematical simulation of ejection and ejection flows in a vortex ejector. The proposed modification of the particle dynamics method allowed describing aerodynamic processes with the help of simple laws of classical dynamics, and modeling them with the help of software of the Delphi 7 System. The author presented differential equations, which were solved by the Runge-Kutt method of the second order. As a result of the solution, the authors determined paths of air elements movement in the vortex ejector, which allowed estimating effective parameters of vortex devices.Results. To study the model, the author developed a program with the possibility to set geometric parameters of the vortex ejector in the interface window and to display the current values of the process parameters.Discussion and conclusions. Proposed mathematical model and computer program make it possible to quantify efficiency of vortex devices at their design stage. The advantage of the proposed mathematical model lies in more accurate calculation of vortex flow parameters from the vortex ejector design and physical properties of ejecting and ejecting flows.Financial transparency: the author has no financial interest in the presented materials or methods. There is no conflict of interest.

Mathematical Simulation and Physical Modeling of Self-Source Magnetization by Liquid Electrolyte Flow

With the increasing requirements for steel quality, the refining conditions are increasing strict. The high-speed movement of molten steel under mechanical or pneumatic agitation can uniform the temperature and composition, and accelerate the collision of the inclusions to eliminate. However, the electromagnetic field has an important influence on the removal of inclusions in steel and the corrosion of refractory materials. The magnetic phenomenon caused by the movement of molten steel needs to be explored. Considering the complexity of high temperature thermal simulation, this work adopted the physical modeling combined with mathematical simulation method, saturated sodium chloride solution was selected to simulate molten steel as a liquid electrolyte, the magnetic phenomenon caused by solution motion was tested and analyzed, and mathematical model of solution motion magnetization was based on discharge mechanism and magnetic vector potential superposition principle, then the variation law of spatial magnetic field generated by liquid electrolyte flow was discussed. The results show that the simulation results agree with that of the physical modeling, and the mathematical model is promising for prediction of the magnetic field generated by liquid electrolyte flow. Under a constant flow speed of 2000 r/min, a magnetic field with magnetic flux density up to 0.15 Gs was produced, which has a significant effect on the refractory corrosion and removal of impurities in the molten steel.

Heteroligand Complexes of Copper(II) with Malonic and Adipic Acids Dihydrazides and L-Histidine

Using the methods of pH-metry and mathematical simulation, we studied the complex formation in the copper(II)–malonic (L)/adipic acid (L')–L-histidine (HisH) ternary systems in aqueous medium against 1.0 M KNO3 solution at 25.0°C. The stability constants of (1 : 1 : 1) heteroligand complexes were determined. Quantum chemical calculations of the structures of heteroligand complexes were performed. It was revealed that the Cu(His)(L)+ and Cu(His)(L')+ complexes exist predominantly in the cis-form.

Gas evolution and the effects on ionic transport inside the lithium-ion battery

PurposeGas evolution within lithium-ion batteries (LIBs) gives rise to safety concerns that question their applicability. The gas evolution is not only the result but also the inducement of performance deterioration of LIBs. In this paper, the growth characteristics and dynamic behavior of gas bubble on the electrode surface are studied, and the interference mechanism of gas evolution on Li-ion diffusion or Li-ion conduction within LIBs is discussed and validated by the numerical simulations.Design/methodology/approachFirst, the mathematical models and simulation method are established. The growth and flow of gas bubble in the serpentine channel on electrode surface, which results from the gas-liquid flow and the effects of surface tension, is modeled by using the multi-phase Navier-Stokes and the volume of fluid method. Integrating Butler–Volmer and Fick’s law, the mathematical model of ions transport in the electrochemical cell is set-up. Second, the motion of gas bubble is tracked, and the variations of bubble shape and characteristic parameters with time are obtained by the computed fluid dynamics (CFD) method.FindingsBased on the CFD results, the battery models and electrochemical simulations are carried out to analyze the ionic transport characteristics. The results show that the microstructural morphology such as the serpentine channel shape and size on electrode surface are important aspects for the gas bubble growth and the local ionic transport. Li ions significantly accumulate at one side of the gas obstacle, hindering the ionic diffusion normally. When the gas bubble blocks the electrolyte, the passage of ions from the positive to the negative is interrupted, and the open circuit zone of the electrochemical cell is formed.Originality/valueThe gas evolution within LIBs is not only a result but also an inducement of its performance deterioration. The primary issues in this study are the growth characteristics and dynamic behavior of gas bubble on the electrode surface, providing the knowledge for the interference mechanism of gas evolution on ionic transport and ultimately leads to significant increase of battery resistance.

Investigation of the influence of temperature-speed mode on the parameters of secondary cooling of continuously casted billet from free-cutting steel

Practically the whole steel, including the free-cutting one, is casting by continuous casting machines (CCM). The technological parameters of the free-cutting steel continuous casting have their features, since the high content of Sulphur and phosphor in the free-cutting steel, necessary for its high machinability, increases the probability of fractures and emergency breach of metal. The purpose of the work was study of influence of temperature-speed mode of A12 free-cutting steel casting on cooling agent consumption in the secondary cooling zone of radial type billet CCM. The CCM mold was 900 long with supporting system on the mold frame of two rows of rollers. The secondary cooling (SC) zone comprised four zones of 340, 2360, 3460 and 3610 mm length. The cooling in the first zone is accomplished by water, in the others – by water-air mist. The study was carried out by application of mathematical simulation method to the process of billet secondary cooling, elaborated by V.N. Selivanov. The temperature of the free-cutting steel billet surface was calculated by zones of secondary cooling at various steel temperature in the tundish. The flow density and water consumption in various SC zones determined, necessary to reach the required variation of billet surface temperature. The dependence of total and specific water consumption for the billet cooling on the metal temperature in the CCM tundish determined.