Журнал Сибирского федерального университета. Серия: Техника и технологии @technologies-sfu
Статьи журнала - Журнал Сибирского федерального университета. Серия: Техника и технологии
Все статьи: 1447
Simulation and calculation of heat transfer in multilayer wall structures based on iterative models
Статья научная
Through heat transfer is considered: heat carrier, liquid medium 1 - wall of arbitrary n layers - liquid external medium 2, cooler. For heat flows, a system of (n + 1) nonlinear equations is considered. The method of excluding unknowns sequentially calculates all values of tw, i. The design scheme allows iterative calculations of wall temperature from one to three layers and, accordingly, five heat flows. The novelty of the solution is that the temperature of the first wall tw,1 and the last wall tw, n+1 are not set, but are unknown. They are calculated using an iterative scheme.If you further increase the number of wall layers, the calculations become cumbersome. We are talking about the explicit expression of all tw, i through formulas based on the manual transformation of equations. Optimally bringing the problem to a closed and defined system (n + 1) of equations for (n + 1) unknown wall temperatures tw, i. This system of equations is easily calculated in mass accessible packets, to which Matlab belongs. The advantage is a matrix solution of the entire system at once. In the case of a system of cylindrical and spherical walls, the problem is also solvable. New coefficients have been established for these systems of equations. Which allows you to save balance equations for heat flows.
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Simulation modeling accounting for reservoir fluid properties heterogeneity
Статья научная
Current article deals with fluid properties heterogeneity. The reasons of this phenomenon are analyzed. 3D digital modeling of formation, saturated with oil having variable properties (density and viscosity) is performed. It is compared with model, built in the frameworks of classic approach, where oil has constant density and viscosity. It is shown, that accounting for oil properties heterogeneity allows making oil field design and planning of different activities more precisely.
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Simulation of a continuous ingots structure formation process
Статья научная
The presented results demonstrate the possibility of mathematical complex model in research of the temperature characteristics pattern changes in polymorphic transformations, isotherms of liquidus and solidus, and other parameters depending on the cooling conditions of the ingot. Shown the possibility of predicting parameters of a continuous ingot microstructure (distance between dendrites, size of the austenite and ferrite grains). Were made microstructure parameter calculations of the continuous steel ignot containing 0.17 % C, 0.62 % Si, 1.4 % Mn at various secondary cooling modes.
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Статья научная
Under study was the reaction of the basic operating performance of the cold low-shrinkage ramming paste (CRP) on the pre-heating conditions of the rammed joint. It was found out that the uncontrolled high-rate heat-up of the cold ramming paste (CRP) loosens the macrostructure and intensifies impregnation of the rammed layer. The controlled delayed rate in the temperature rise of the inter-block joint up to 400 °С enables to obtain a high-quality layer of paste with the improved barrier properties against its impregnation with electrolyte.
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Simulation of three phase induction machine
Статья научная
Three phase induction motor is the most popular type AC motor. it is very commonly used for industrial drives. It is cheap, robust, efficient and reliable. It has good speed regulation and high starting torque. It requires little maintenance. It has a reasonable over load capacity. This paper deals with the simulation of three phase induction machine using MATLAB Simulink. The results are obtained for generating mode and motoring mode.
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Simulation of wind speed in the problems of wind power
Статья научная
The article is devoted to research of mathematical models of wind speed and development a way to improve the efficiency of wind power plants based on fuzzy logic using fuzzy model of the wind speed. Simulation of the wind speed is a fairly difficult task, since this source of energy is constantly changing in time and space. Four basic models of wind speed were identified at the end of research work: determinate, probability, spectral and fuzzy. Every one finds their own field of application. Thus, from the energy point of view, the model probabilistic distribution of Weibull is most applicable at the level of technical and economic development. Deterministic model allows to determine the power generated by wind turbines at a given average wind speed. The spectral model should apply in those studies where necessary to account for gusts of wind and sudden changes. Fuzzy model of the wind is the most convenient and relevant for modeling of wind turbine control, it is allows to form a flexible control system.
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Smart materials in materials science
Статья научная
The basic categories of materials which form the row in order of complication of their performance such as simple–multifunctional–adaptive–active–smart are considered. Energy aspects of external effects upon materials, and behavior of materials response to the stimuli of physical, chemical and biological nature, are examined. A model of smart material is proposed as the atom-molecular structure provided with a feedback system which corrects the primary reaction of material upon effect of surroundings via optimal usage of its energy.
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Статья научная
The article presents the results of software development for predictive maps modeling of the earth’s surface processes based on time-varying satellite data using the probabilistic and spatial characteristics of various types of the earth’s surface in the image. The analysis of existing methods for the assessment and modeling of the state of landscapes of various territories using satellite Earth monitoring data is presented. The review of existing systems of the earth’s surface dynamics analysis and their main advantages and disadvantages is given. The cellular automata method was used to implement the forecast. This method allows complex systems modeling using a simple set of rules and is the most convenient and accurate method for working with a space images. Algorithms and basic modeling parameters for using this method are described. The developed software makes it possible to forecast the state of the surface of the territories under consideration based on a series of time-varying data, and also to specify various modeling parameters in order to improve the accuracy of forecast maps. The results of the developed software testing with MODIS and Landsat data are presented, the accuracy of the forecast and the influence of simulation parameters on the result were estimated.
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Solution of the problem of flow past a wing profile near the interface
Статья научная
In this paper presente some approaches to solving the problems of flow past a wing profile near the interface. Studies on the flow in the vicinity of separation boundaries (solid walls and free surfaces) show that in a confined flow liquid turns into a bubble mixture of liquid and gas. This complicates the flow analysis and introduces additional losses resulting in impaired energy performance of the concerned mechanisms. In a general case the problem of a two-phase compressible flow around various types of vane mechanisms is substantially nonlinear (even under no-vortex flow assumption).
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Sorption cleaning of galvanic wastewater from Fe ions (II), (III) and reuse of sorbent IPI-T
Статья научная
The sorption method of wastewater cleaning from ions of Fe (II) and (III) using carbon sorbent IPI-T synthesized in the Irkutsk State Technical University. Particular attention is paid to the regeneration of the carbon sorbent saturated with ions of Fe (II) and (III),by the chemical treatment method. Was studied the reuse of the sorbent for the purification of galvanic wastewater.
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Статья научная
The purpose of this work is to assess the long-term changes in the state of forest vegetation on the territory of the Nature Reserve “Stolby” for the period 2000-2018. An algorithm has been developed for this and a map of the spatial distribution of the average annual NDVI trends of forest vegetation according to MODIS satellite data has been created (May - September as averaging period). In the work, a map of vegetation cover was used according to the electronic ecological atlas of the Nature Reserve “Stolby”. The analysis of the distribution of the number of pixels on the values of the average annual NDVI trend revealed that for the class of coniferous vegetation negative values of the linear trend prevail (by 30%). For the deciduous vegetation class, the number of pixels with negative values of linear trend slope is 3.1% higher than with positive ones. In general, for most types of forest vegetation negative trends NDVI prevail. The negative NDVI trend slope of vegetation indicates degradation processes. The reasons for this are the changes of climatic factors, anthropogenic impact, fires, aging and forest vegetation diseases.
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Статья научная
The objective of the study is to assess the state of agricultural seeds (level of weediness) on the territory of the Krasnoyarsk Agricultural Research Institute of Federal Research Center «Krasnoyarsk Science Center of the SB RAS» near the village Minino according to satellite data. For this purpose, an algorithm for obtaining and processing PlaneScope satellite data for calculating the NDVI vegetation index of agricultural seeds has been developed. On its basis a map of the spatial distribution of NDVI wheat seeds with different levels of weediness has been created. According to PlanetScope satellite data, an opportunity to interpret areas of wheat seeds with high and low levels of weediness has been shown. It has been found that the NDVI value of pure plantation of wheat with a low level of weediness is greater than the NDVI value of wheat seeds with a high level of weediness.
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Speciality of sulfide minerals alteration of copper-nickel ores
Статья научная
Grain-size class redistribution of non-ferrous, precious metals and iron in copper-nickel ores tailings from Norilsk industrial region was after artificial weathering investigated. Possible mechanisms of metal redistribution were suggested.
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Статья научная
The paper presents the results of the analysis on measured parameters of harmonics at the node of the high-voltage network. The measurements were made at the node connecting the pulp-and-paper mill to the 220 kV supply network. This load is nonlinear and has a large capacity. Particular attention is paid to the distributions of the current and voltage harmonics. The paper clearly shows probabilistic properties of the measured parameters of harmonics.
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Статья научная
The design of active hydrostatic radial bearing with smooth cylindrical surfaces and lubricant output flow restrictors in the form of movable rings on membrane suspension is presented. The device is several times less power-consuming compared with known devices of flow control. The bearing has a negative and zero compliance (infinite stiffness), and therefore can be used in machine tools to suppress the negative influence of elastic system deformation on the accuracy of processing. On the basis of two-dimensional model of lubricant flow developed a mathematical model, method and procedure for calculating the bearing load capacity and flow rate. It is established, that the calculation of static characteristics of bearing in the entire range of operating loads can be correctly performed only on the base of two-dimensional model. For small eccentricities the characteristic of zero and negative compliance can be calculated with sufficient accuracy by the simplified method, based on one-dimensional motion of lubricant flow. Bearing of zero or negative compliance have load capacity range, which is 20 - 50% more than conventional bearings of the same overall dimensions. The setting of input throttling slits resistance decisive influence on the optimal static characteristics of the bearing. The optimal values of its resistance for conventional and active bearing are practically identical.
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Statistical regularities of chronology of astronautics
Статья научная
In article chronological anomaly of astronautics is described and investigated by methods of mathematical statistics. The binomial law of distribution of number of chronological coincidence is proved. It is shown, that the probability of casual occurrence of considered coincidence is rather small.
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Stochastic simulation of covariance matrix and power load curves in electric distribution networks
Статья научная
An algorithm of stochastic simulation of covariance matrix and nodal power load curves is developed for electric distribution networks based on factor analysis. Statistical stability of factor power load model is confirmed. Application of this model is able to identify a general regularity of nodal power changing, and to simplify the analysis of multivariate operating conditions in operational problems of electric distribution networks and their optimization.
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Статья научная
Work is devoted research of features of structure formation processes in the contact zone of limited solubility bimetals and alloys subjected to plastic deformation. It is established, that the plastic deformation of limited solubility metals (Al-Ti, Al-Ni), can significantly broaden the scope of their mutual solubility. The appearance of zones of local tensile and compressive stresses (curvature crystal lattice zones) leads to increased solubility, emergence of new phases and redistribution of their composition, reorientation of granular structure.
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Structural topological analysis of cardiac conduction system
Статья научная
In this paper the method of structural-topological analysis of cardiac conduction system based on wavelet analysis of electrocardio signal reflecting conductive network of heart topology has been considered.
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Статья научная
The purpose of this work was to study the chemical changes, taking place during the initial stage of the interaction of butadiene rubber and its vulcanized product with nitric acid by means of the differential IR spectroscopy. Thus some mechanistic knowledge, associated with the complex nature of this process could be obtained.
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