Статьи журнала - Журнал Сибирского федерального университета. Серия: Техника и технологии
Все статьи: 1404
Formation of nanomaterials based on non-ferrous and noble metals in autoclaves
Статья научная
The physicochemical laws of formation of multicomponent phases containing noble metals in hydrothermal conditions were investigated. Approaches to a purposeful variation of structure and composition of mono-, bi- and polymetallic phases based on non-ferrous and noble metals were realized. Structural, phase and chemical stability of polymetallic nanostructures in some carrier materials was investigated.
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Full analysis of Sierra Leone bauxite and possibilities of bauxite residue filtration
Статья научная
Chemical analysis, classical or instrumental using ICP and the XRF spectrometry, offers complete information on elemental composition and major chemical constituents of bauxite and bauxite residues resulted from the Bayer process. The XRD diffractometric analysis provides information on quantitative mineralogical composition of these materials and it enables the real identifi cation of main chemical combinations, whose reactivity is essential in driving the process of obtaining alumina through the Bayer process. Mineralogical components identified in the bauxite samples were Gibbsite (30-40 %), Al - goethite (20-30 %) and hematite (less than 5 %). About 40 % of the Sierra Leone bauxite mineralogical phases were found in amorphous state, but all these amorphous phases are also originating from the above crystalline components, under the excessive wearing during bauxite deposit formation and its metamorphic transformations. The minor crystalline components from bauxite are: kaolin, quartz, zircon, ilmenite and anatase, but their concentration is below 2 % (close to the detection limit of the XRD analysis). The main mineralogical components identified in red mud are the Al-goethite (35 %) and the hematite (12 %). The minor crystalline components from red mud are: gibbsite, katoite, sodalite, calcite, rutile and anatase. Experimental data of this type of bauxite have shown that a compact mass of approximately 50-55 % of bauxite passes fully untransformed through all important stages of the Bayer process. This material of uniform size and composition can form a structure with low hydraulic resistance, easy filterable both on conventional or hyperbaric steam fi lters.
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Further developments and advantages utilizing slotted anodes
Статья научная
Slotted anodes have been used by smelters that require large size anodes. Being inter-anode separations, slots can be considered acting as expansion gaps to safely absorb the heat-induced expansions. The slots are helping to reduce the thermal stresses in the anodes and thus reducing the risk of cracking. Approach to slots cut in the bottom surface of the anodes has nowadays changed and become extremely important, since they represent effective ways to escape gas continuously formed during Aluminium reduction process, thus reducing the accumulation of gas bubbles underneath the anodes. For this reason the use of slots in the anodes allows to reduce electrical cell resistance as well as to improve cell stability. Slots in the anodes therefore result in reduced electrical power consumption for the Aluminium production. The depth of the slots is important to ensure that these benefits last throughout the entire life of the anodes (“ full-life slots”), while slot shape, which determines the gas escape direction and related areas of influence, is also important to achieve further benefits in pot management. Cutting slots with reduced width reduces the amount of carbon removed from anodes when slots are cut. Narrow slots are improving specific Aluminum production per anode as well as prolonging anodes cycle time.
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Harmonics and neutral line current compensation in three-phase four-wire power systems
Статья научная
Load unbalance and modern office equipment result in a significant neutral current in three-phase four-wire low-voltage power systems. This paper considers a new configuration of hybrid power filter for power quality management in three-phase four-wire low voltage power systems. The proposed hybrid filter is composed of a single-phase power converter and a three-phase passive filter connected in series. The hybrid filter can be operated in both passive and hybrid mode. The compensating performance of the filter is confirmed with computer simulation using MATLAB software. Analysis and simulation proved that the hybrid filter is an effective solution for neutral current mitigation.
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Статья научная
This paper is reporting the data of a preliminary study on heavy metals distribution in the fluid and solid phases involved in dry and classified aluminium hydroxide production through Bayer process. For heavy metals released in the fluid phases, the main source of contamination is the bauxite through its mineralogical phases soluble or insoluble in alkaline solution. It was shown that predominant way to transfer contaminating elements in aluminium hydroxide particles is the occlusion of very fine particles coming from mineralogical phases of bauxite residue. New born mineralogical phases from bauxite residue, like poor crystallized sodalite and cancrinite, are the most active occlusion contaminants.
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High gain Ku-band substrate integrated waveguide slot antenna array
Статья научная
16 x 16 element waveguide-slot antenna array at 14.4 GHz is described. Antenna is built using substrate integrated waveguide (SIW) technology. Simulated and measured characteristic of fabricated antenna are presented.
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High-level design flows for VLSI circuit
Статья научная
Design flows for very-large-scale integration circuit are considered. The problems arising from the realization of the project using top-down and system design methods are highlighted. The technology of an architecture-independent design for computer systems on a chip is suggested. The technology is based on a functional data-flow presentation of the initial algorithms and their subsequent step-bystep transformation at the register transfer level into description of the system being designed. Using methods of formal description and verification allows developers to transfer initial high-level parallel algorithms on topologies of the confi gurable integrated circuits being developed.
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Hydraulic calculations of earthen channels for reconstruction
Статья научная
The problems in the design, operation, and reconstruction of earthen channels analyzed on the example of Mirishkor canal. The need for a new approach to the reconstruction have been defined using the results of field study and HEC-RAS modelling software. Recommendations are given for improving the hydraulic calculation of irrigation canals.
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Hydrodynamic dispersion of calcium aluminosilicate from technogenic and nonmetallic materials
Статья научная
Physicochemical properties of two calcium aluminosilicate materials after reducing in the hydrodynamic rotary generator in supercavitation mode were studied. The samples are the crystal ceramic foam based on Kansko-Achinsk lignite-ash and the porous glass material obtained from low-manganese nonmetallic feed. X-ray phase analysis, EPR-method, NPR-method (the Mossbauer Effect) and optical microscopy were used. It was found that the material is changing its stucrure in a hydrodynamic dispersion process caused by high-cavitation. The nature of the changes depends on its initial state.
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Hypergene units of the Proterozoic Tatar carbonatite formation of the Yenisey Ridge
Статья научная
The Yenisey Ridge Proterozoic carbonatite and metasomatite unit developed in the belt of near-meridian strike, 20×2-5 km in size, is described. Dolomite carbonatites host en echelon beds of pyrochlore-apatite ores with the average Nb 2 O 5 grades 0.23 % and the average P 2 O 5 grades 4.71 %. Apatite beds are locally developed. As for metasomatites, muscovite-biotite mica is of specific interest. Cretaceous-Paleocene kaolinite-hydromica weathering crusts of aluminum silicate rocks and polygenetic unconsolidated compositions on carbonatites, representing vermiculite-clayey ochers in combination, are developed in the northern part of the productive zone. Crandallite-bearing ochers with higher Nb 2 O 5 grades are developed in the southern part in the aleurite ferriferous material. In the northern part of the zone the pit mines granular ores consisting of pyrochlore and columbite crystals in the francolite-vermiculite-clayey material. Vermiculite and francolite are stored in special dumps. The author recommends using phosphates of bedrock deposits, special dumps and slimes as a resource for fertilizer production.
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IMS quality of service estimation with tensor concept
Статья научная
In this work, we propose methods of tensor analysis for the IMS network QoS characteristic estimation. Modern communication networks are representing a set of devices, systems and networks with the given interaction structure for a heterogeneous information streams processing. QoS support is a necessary mechanism for rendering of services in a modern communication networks but it increase cost and complexity equipment of service providers. In present, the main mathematical apparatus of QoS estimation is a queuing theory but it has some drawbacks. It should be noted that the base of next generation networks is an IP Multimedia Subsystem (IMS). IMS network have a many systems and complicated topology. Consequently, the task of supply QoS and QoS characteristic estimation in IMS is a very important for communications development. However, the efficient allocation of network resource management is complicated because it needs management many systems and processing the considerable amount information streams with a specified QoS for every type of the streams. Tensor analysis of networks provide opportunities to take into account the process-structure interaction and the application flexibility that result in the compute cost decreasing, the delay reducing due to dynamic management infocommunication systems and the good network scalability.
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Статья научная
The alumina concentration in the bath plays a fundamental role on cell operation. Local depletion may lead to an anode effect when using carbon anodes. A mathematical model describing the alumina convection-diffusion process in the bath coupled to the cell magneto-hydrodynamic (MHD) in the presence of small bubbles is presented. Small bubbles may be assumed when slotted anodes are used. The relative importance of the velocity felds generated by the magnetic effects and/or the small bubbles on the alumina concentration in the bath is discussed.
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Implementation of moving object tracker system
Статья научная
The field of computer vision is increasingly becoming an active area of research with tremendous efforts being put towards giving computers the capability of sight. As human beings we are able to see, distinguish between different objects based on their unique features and even trace their movements if they are within our view. For computers to really see they also need to have the capability of identifying different objects and equally track them. This paper focuses on that aspect of identifying objects which the user chooses; the object chosen is differentiated from other objects by comparison of pixel characteristics. The chosen object is then to be tracked with a bounding box for ease of identification of the object's location. A real time video feed captured by a web camera is to be utilized and it's from this environment visible within the camera view that an object is to be selected and tracked. The scope of this paper mainly focuses on the development of a software application that will achieve real time object tracking. The software module will allow the user to identify the object of interest someone wishes to track, while the algorithm employed will enable noise and size filtering for ease of tracking of the object.
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Improving safety of shielding chambers equipped with viewing windows
Статья научная
The article describes and proves the possibility of increasing the protection against neutron radiation for personnel by means of immersion liquid without major changes in the design of the equipment used and without reducing the safety of the radiation object. Studies of the components properties of the protection glass and the immersion liquid have shown that the properties of the immersion liquid reduce the dose rate of neutron radiation significantly compared to the protection glass, which is used for the main protection against ionizing radiation when working with uranium- plutonium fuels. The use of two-layer protection in viewing windows allows reducing the dose rate of mixed gamma-neutron radiation to values that do not exceed the safe radiation dose for personnel when working with an ionizing radiation source, which in this case is 50 kg of uranium-plutonium fuel.
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Improving the quality of polymer-modified asphalt coating binder by settling resin of pyrolysis
Статья научная
The quality of binder in asphalt mixes largely determines the characteristics of road surface. In the present study the possibility of modifying the binder by introducing the settling resin of pyrolysis of wood raw material into bitumen is considered in order to improve adhesion of bitumen to stone materials and to improve the quality of asphalt concrete.
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Статья научная
The In work it is shown that the hydroacoustic channels of impulse noise or short-term interruptions for improving the quality of data transmission can be applied different variants of convolutional and cyclic codes. Convolutional codes at a rate of R ≤ 3/4 in conjunction with broadband signals (BBS) or convolutional codes R ≤ 2/3 with code interleaving algorithm can reduce the probability of an error at the output channel for the known error statistics. Taking into account the energy gains from the computational complexity of encoding and interleaving of code is more favorable option “code + BBS” to 4÷5 interlaces. Given the multi-bit optimal filter BBS, its implementation is always more diffi cult than implementing a threshold decoder trellis.
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Статья научная
Possible ways to increase the scope of application of multi-rope friction hoists are considered. Theoretical calculations are given.
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Induction heating of the filling conveyor molds
Статья научная
In the smelting and foundry production of aluminum ingots, filling conveyors are widely used. Aluminum ingots of a certain shape and weight are obtained by crystallizing liquid aluminum (melt) in the molds of the filling conveyor. As the mills move along the conveyor, the melt gradually hardens in them. In high-performance conveyors, the mills move through the water to increase the cooling rate of the melt. Therefore, after the mill is freed from the hardened ingot, water enters it. In order to avoid temperature shock and possible release of liquid metal, the molds must be dried and heated before pouring. At present, gas burners are used in aluminum plants for this purpose [1]. The purpose of this work is to study the possibility of induction heating of the filling conveyor molds.The calculation is carried out using Fourier series in complex form and approximate boundary conditions on the surface of ferromagnetic molds. The approximate boundary conditions avoid the need to calculate the electromagnetic field in a nonlinear ferromagnetic medium.In the heated object, the energy of the induced alternating electric field is irreversibly converted into thermal energy. This dissipation of thermal energy, which leads to the heating of the object, is determined by the presence of conduction currents (eddy currents).Induction heating is widely used in metallurgy for melting, heating and mixing of electrically conductive bodies. The method is based on the absorption of electromagnetic energy by bodies of an alternating magnetic field created by an inductor. The heated product is located in the immediate vicinity of the inductor. There are many publications on analytical and numerical, analysis of physical processes in the inductor-heated billet system. In this paper, an analytical calculation of electromagnetic processes in the system of inductor - ferromagnetic molds of the filling conveyor is carried out. The analytical solution is obtained by using the approximate boundary condition of L. R. Neumann on the surface of nonlinear ferromagnetic molds.
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Influence of basalt fibre on foam concrete structure
Статья научная
In this paper research of the structure of dispersely - reinforced basalt fibre cement stone with the purpose of getting foam concretes with improved performance characteristics is carried out. The results are given of the study of the processes of structure formation of the cement system, dispersеly - reinforced by basalt fibre, consisting of a number of thinner fibres that actively interact with cement matrix in a chemisorbed manner. Interaction takes place only in the surface layer, basalt fi bre integrity being preserved in the cement stone. The effect of «fullness» is observed at that and availability of cement adhesive vacuum absorption is assumed. The suggestions mentioned are confirmed by physical and mechanical tests of foam concrete samples possessing enhanced durability, frost resistance and longevity.
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