Журнал Сибирского федерального университета. Серия: Техника и технологии @technologies-sfu
Статьи журнала - Журнал Сибирского федерального университета. Серия: Техника и технологии
Все статьи: 1447
Magnetization of a pyrrhotite of composition Fe0.847S in area of a Curie point
Статья научная
The x-ray, Mossbauer and termomagnetic researches of pyrrhotites possessing high-temperature λ - peak (Тλ = 310 C) on curve dependence of magnetization on temperature - I (Т) are lead. The chemical compound and conditions of formation of such pyrrhotites is determined. It is established, that samples with λ - peak possessed the raised maintenance of sulfur in comparison with pyrrhotites Fe7S8 and corresponded to structure Fe1-nS (n=0.153). As has shown experiment, these pyrrhotites are in a metastable phase condition and in due course (samples were observed during 29 years) pass in a pyrite and a pyrrhotite of structure Fe7S8 (at the presence of an atmosphere the Goethite and a szomolnokit was formed also). Because of quantum-mechanical calculations of dependence of specific magnetization from temperature for various underlattices with various integral of exchange interaction good conformity of a settlement curve with experimental is received. Calculations were made within the framework of model of a molecular field for a two-sublattice ferrimagnetic.
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Статья научная
This article present main characteristics of aluminum alloys with high dispersion ability of phase of alloying elements. Examined future development in the field of obtaining heat-resistant and high-strength aluminium alloys, as well as alloys for special purposes.
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Статья научная
This study employed an algorithm of vegetation cover mapping based on a spatial analysis of Landsat OLI satellite imagery, a digital elevation model (DEM) and field data using geographic information systems (GIS) and expert knowledge. Applying this algorithm, maps of vegetation types and vegetation growth conditions were built for the test site in the northern part of near-Yenisei Siberia (Krasnoyarsk region). The spatial analysis of these two maps with field samples were used for the extrapolation and mapping of soil carbon stock volumes (kgC/m2).
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Статья научная
This article covers the use of analytical technique of solutions for flexural and longitudinal oscillations of the bearing framework of a railcar body frame in the form of an elastic core of variable section with a variable weight, flexural and longitudinal rigidity. The calculation is performed for the modernization of the body frame of emergency and repair rail service car, taking into account the variability of section, mass, longitudinal and bending stiffness along the length to prolong the service life of their useful operation.
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Статья научная
Peculiarities of geometry elements synthesis of wave transmission with a rolling (cog) rack, its kinematics and simulation interaction of discrete wedge pushers with rolling rack are considered here. Principles of drive creation and systems of microprocessor control of the mechatronical module of the translation by using wave transmission with the rolling rack as well as the main appraches in design-technological preparation of its making are presented.
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Статья научная
Proposed new ways of obtaining rods-modifiers from aluminum and aluminum alloys. Were researched of their modifying ability and tested in industrial conditions modification technology in the production of aluminum alloy ingots.
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Method and device for compression of the non stationary signals
Статья научная
In the report a new method and the operation of the device of statistical compression of non-stationary pulse signals are described. The pulse signals are characterized by, first of all, weak irregular period of signal, e.g. electro cardio signals (ECS). It is shown that construction and processing the ECS histogram provide high value of the compression.
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Статья научная
This article is devoted to development of a method for assessing NDVI dynamics in northern territories and analysis of NDVI dynamics of vegetation on the territory of the Krasnoyarsk region using MODIS/Terra satellite data for the period (2000-2020). Spatial distribution map of average annual vegetation index NDVI has been made, indicating five latitudinal sections through the territory of the Krasnoyarsk region: the coordinates (latitude from 52˚ N to 76˚ N, longitude from 91˚ E to 95˚ E). Latitudinal variability of NDVI index for 20 years of measurements has been studied. Heterogeneity of long-term dynamics of vegetation has been discovered depending on the latitude of the studied territories. Efficiency of the suggested method for identifying long-term NDVI trends has been shown. A positive NDVI response of the vegetation cover of northern territories of the Krasnoyarsk region to climatic changes over the last 5 years has been revealed.
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Methodology to optimize the anode performance
Статья научная
An aluminium smelter operating its pots with Soederberg technology has experienced a period with a very high number of anode problems, mainly occurring as spikes, hanging anode ends, leak in stud holes, vertical cracks and dusting. The anode problems hindered a planned amperage increase. This paper describes the methodology that was applied to identify the root causes of the problems and to solve them systematically. This methodology includes the following main steps: Initial plant audit; Revamping of equipment causing bottlenecks; Plant capability test; Dynamic process optimization DPO; Validation of improved anode quality and pot performance. By applying this methodology, the anode problems of the smelter could virtually be eliminated. As a consequence the key plant performance figures (current efficiency, carbon consumption, energy consumption and bubble noise) could be improved substantially. This allowed to increase the line current by 7 %.
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Methods for assessing the state of snow-ice cover
Статья научная
The development new methods for measuring the electrophysical and geometric parameters multilayer dielectric medium in order to identify their layers, as well as to detect inhomogeneities in them, is an urgent scientific task. Methods for assessing the state the snow-ice cover are proposed, based on the identification layers of the snow-ice cover by the dielectric permittivity obtained indirectly as a result inclined sounding of the underlying surface by an electromagnetic wave with vertical and horizontal polarization. Under normal sensing the underlying surface, in the form snow-ice cover, by radio waves with vertical and horizontal polarization, the obtained values the reflection coefficient from the boundary layers the received signals are identical. Oblique sensing by a vertically polarized wave in the range from 25 to 90 degrees leads to a sharp dip in the values the reflection coefficient from the boundary layers at certain angles, so for dry snow - 47…55°, dry firn - 55 … 58° and dry ice - 58…61°. These angles characterize the dielectric properties the layers (permittivity), which are explained by the complete polarization the reflected wave in a plane perpendicular to the plane incidence, since at this moment the vibrations the layer's electrons along the direction their movement do not lead to the emission electromagnetic waves in the direction the reflected wave (absent). The given estimated values the complex relative permittivity snow-ice cover as two component medium air and ice at a temperature from minus one to minus forty degrees, or three component medium air, ice and water at zero temperature are a sample for establishing the identity the characteristic properties layers. The purpose this article is to develop methods for assessing the state snow-ice cover used in determining the possibility performing a safe landing a helicopter - type aircraft on an unprepared site with snow-ice cover based on the identification the obtained characteristics snow-ice cover layers based on the results radar sensing with calculated data.
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Methods for preventing ferrocene catalyst migration into solid fuels
Статья научная
Ferrocene compounds are among the most common solid fuel combustion speed catalysts, which have attracted the attention of scientists due to better combustion speed, ease of production, purity percentage and high efficiency. Due to their high migration, the main problem of these compounds is their migration during storage, which can reduce engine performance and cause subsequent risks. Various methods have been proposed to solve this problem, including branching, adding active groups and creating bulky compounds or strengthening intermolecular bonds, polymerization, excessive branching, etc., due to the high importance of the migration phenomenon. In the exploitation of solid fuels, this article introduces ferrocene-based combustion rate catalysts and briefly reviews methods to prevent their migration.
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Micro-LIF and numerical investigation of mixing in microchannel
Статья научная
Flow regimes and mixing pattern in a T-type micromixer at high Reynolds numbers were studied by numerical solution of the Navier–Stokes equations and by particle image velocimetry (micro-PIV) and laser induced fluorescence (micro-LIF) experimental measurements. The Reynolds number was varied from 1 to 1000. The cross section of the mixing channel was 200 μm×400 μm, and its length was 3000 μm. Five different flow regimes were identified: (I) steady vortex-free flow; (II) steady symmetric vortex flow with two horseshoe vortices; (III) steady asymmetric vortex flow; (IV) unsteady periodic flow; (V) stochastic flow. Maximum mixing efficiency was obtained for stationary asymmetric vortex flow. In this case, an S-shaped vortex structure formed in the flow field. Good agreement between calculation and experiment was obtained.
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Micrometeorite impacts in beringian mammoth tusks and a bison skull
Статья научная
We have discovered what appear to be micrometeorites imbedded in seven late Pleistocene Alaskan mammoth tusks and a Siberian bison skull. The micrometeorites apparently shattered on impact leaving 2 to 5 mm hemispherical debris patterns surrounded by carbonized rings. Multiple impacts are observed on only one side of the tusks and skull consistent with the micrometeorites having come from a single direction. The impact sites are strongly magnetic indicating significant iron content. We analyzed several imbedded micrometeorite fragments from both tusks and skull with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and X-ray fluorescence (XRF). These analyses confirm the high iron content and indicate compositions highly enriched in nickel and depleted in titanium, unlike any natural terrestrial sources. In addition, electron microprobe (EMP) analyses of a Fe-Ni sulfide grain (tusk 2) show it contains between 3 and 20 weight percent Ni. Prompt gamma-ray activation analysis (PGAA) of a particle extracted from the bison skull indicates ~0.4 mg of iron, in agreement with a micrometeorite ~1 mm in diameter. In addition, scanning electron microscope (SEM) images and XRF analyses of the skull show possible entry channels containing Fe-rich material. The majority of tusks (5/7) have a calibrated weighted mean 14C age of 32.9 1.8 ka BP, which coincides with the onset of significant declines
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Modeling of heat exchange processes under electrocontact cutting of metals
Статья научная
The mathematical model of a thermal condition of blank under electrocontact cutting has been offered. The way of the improvement of electrocontact cutting is recommended in order to improve the technological indicators of a process at the expense of temperature regulation in a cutting zone under observance of the calculated modes of processing.
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Modeling of structure evolution during hot rolling of aluminum alloys in the software package Deform
Статья научная
The study provides modeling of aluminum alloy 5182 БТ (Al-Mg 4,5%) structure evolvement during hot rolling in each stand of 5-stand continuous hot rolling mill. Mathematical modeling was made in DEFORM software product, Johnson-Mehl-Avrami-Kolmogorov equation was used for recrystallization kinetics setup. DEFORM enables to consider recrystallization of three types: dynamic, meta-dynamic and static recrystallization. Proceeding from actual rolling process temperature and speed parameters, the task was converted to static recrystallization calculation. Input coefficients were taken from literature data review. The output is volume of recrystallized grains and their sizes calculated throughout the rolling process. Description of processes related to grain size changes in rolling aluminum alloys is peculiar due to lack of consistent patterns. This is explained by the fact that grain growth during rolling is influenced by many factors associated with both internal metal structure and individual process specifics. That is why modeling results should be compared with industrial experimental data. In this case, texture and structure evolvement data received as a result of Hot Rolling Mill 2800 forced stop with subsequent quenching of metal were used for comparison.
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Modeling thermal conditions of the process combined rolling-extruding
Статья научная
Were obtained the dependences and through them analyzed the thermal interaction of the metal and the tool during combined rolling-extruding. Given graphs temperature change of deformable metal to obtain rods by method CRE at various geometrical and technological parameters of the process.
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Статья научная
The article introduces modernizing the global approximation method of the posterior probability density function in the implementation of phase-locked loop algorithms which improves the accuracy of clock synchronization in telecommunication networks, and reduces the time of entering into synchronism.
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Статья научная
The problem of temperature anomalies is typical for all major cities in the world. Space thermal images are a powerful source of information for analyzing and determining outlines of temperature anomalies within a single territory. Determination of the nature and boundaries of temperature anomalies will help to understand the causes of the unfavorable ecological situation in Krasnoyarsk: where, in addition to high industrial emissions, atmospheric processes also exert their influence, which lead to the fact that impurities linger and concentrate over the city. The development of advanced space technologies allows the collection of a variety of diverse data more efficiently and at a lower cost than the organization of an appropriate ground network of observation posts and points. One of the most interesting and important indicators about the surface of the Earth is the land surface temperature. Land surface temperature is determined by the balance of incoming and outgoing energy. The main and overwhelming source of energy coming to the surface of the Earth is solar radiation. The 10th and 11th bands of Landsat 8 satellite measure thermal infrared radiation (TIR). The thermal infrared range is particularly useful for determining the temperature difference between the city and surrounding rural areas, and for studying the phenomenon of an urban heat island (UHI).
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Monte Carlo numerical method in the problem of temperature stability analysis of electronic devices
Статья научная
The problem of ensuring high temperature stability of parameters by reason of the characteristic features inherent in the integral performance becomes especially urgent for microminiature electronic devices. For the mathematical description of the electronic devices’ temperature error it is proposed to use the method of experiment’s statistical planning in combination with regression analysis. There are classes of electrical circuits in which the output parameter depends mainly on one-parameter electrical radio elements. In the article it is shown that the problem of obtaining the temperature error equation for such electrical circuits can be reduced to the problem of effective finding of the one-parameter electro radio elements’ influence coefficients. A modification of the Monte Carlo statistical method with the computational factor experiment’s scenario to find the temperature error equation is considered. Approbation of the proposed modification is carried out using the example of the electric circuit of the generator with the Wien bridge.
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Статья научная
NMR Imaging results of polymethylmethacrylate colloidal crystals infiltration are presented. For infiltration study the colloidal silica and fluids with different relation of surface tension and viscosity were utilized. Wetting front has a trend to be steady while propagated into bulk sample as revealed by means of NMR Imaging. As regards of powder sample, the wetting front instability was observed. Both the wetting front dynamic and structural properties of samples namely porous media permeability, fractal dimension of porous space and tortuosity were successfully measured. NMR Imaging techniques was demonstrated to be suitable for noninvasive study of infiltration processes occurred in the course of inverse opals preparation.
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