Статьи журнала - Журнал Сибирского федерального университета. Серия: Техника и технологии
Все статьи: 1367
Numerical studies of coal bed fracturing for effective methane drainage
Статья научная
An effective methane drainage from the coal seam is essential for safety mining operations. This paper describes the algorithm used for calculating trajectory of crack formed by the hydraulic fracturing carried out in parallel wells. The results of numerical analysis show that direction of crack propagation is affected by the pressure applied and surrounding rock’s stress state. The maximum possible distance between hydraulically fractured wells at which they linked was estimated. The obtained results help to design hydraulic fracture treatments in coal measure rocks in order to solve the problem of underground methane production or intensification of beds degassing.
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On creation of multi-wave screens
Статья научная
In this article, an attempt on theoretical justification of design of a multi-wave separator for dispersion of ultrafine powders is made. The advantages of such separator, as compared to the ordinary one, are specified. The characteristics of materials appropriate for creation of real designs of multi-wave screen-separators are considered.
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On the choice of some modifiers when creating composite nickel-phosphorus coatings
Статья научная
The article considers the issues of choosing some modifiers of composite nickel-phosphorus coatings (CNiPC) using the method of crystal-chemical design in order to create high reliability and durability in the friction units of machines and mechanisms of tribological systems (TS). The paper shows the possibility of improving the tribological and anti-corrosion properties of NiP coatings without modifiers by introducing modifying additives into the coatings - ultradisperse powders of simple and complex metal oxides, oxides with corundum and rutile structures, simple substances with magnesium and tungsten structures, and polytetrafluoroethylene.
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On the design of solar energy tracker system
Статья научная
Solar energy is a very important means of renewable energy resource. With solar tracking, it will become possible to generate more energy since the solar panel can maintain a perpendicular profile to the rays of the sun. Even though the initial cost of setting up the tracking system is considerably high, there are cheaper options that have been proposed over time. This paper discusses the design and construction of a prototype for solar tracking system that has a single axis of freedom. Light dependent resistors (LDRs) are used for sunlight detection. The control circuit is based on an ATMega328P microcontroller. It was programmed to detect sunlight via the LDRs before actuating the servo to position the solar panel. The solar panel is positioned where it is able to receive maximum light. As compared to other motors, the servo motors are able to maintain their torque at high speed. They are also more efficient with efficiencies in the range of 80-90 %. Servos can supply roughly twice their rated torque for short periods. They are also quiet and do not vibrate or suffer resonance issues. Performance and characteristics of solar panels are analyzed experimentally.
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On the determination of the main parameters of a dam compactor
Статья научная
The article highlights the issues of determining the main parameters of a dam compactor of a mounted trencher for cutting temporary sprinklers. It also finds out the angle of advance of the compaction soil of the inner part of the ditch using a conical roller and the outer part of the ditch that determines the parameters of the ditch and working body.
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Статья научная
Neodymium and strontium isotopic composition and rare earth elements (REE) distribution pattern have been determined in whole rocks and minerals were separated from host metamorphic rocks and disseminated sulfide ores of the Blagodat gold deposit. Isotopic data are given to construct few isochrones that could be reflected an age of main stages of metamorphic and metasomatic alteration in rocks varieties during a successive accumulation of gold in structural traps. The significant temporal range in the forming of the studied rocks can be interpreted as an evidence of multi-stage tectonic destruction accompanying with trust-folding processes, shear deformations and development of local fracture zones that had place from the Late Riphean to Middle Paleozoic time. According to isotopic data basic ore-forming processes were realized in the relatively narrow interval from 690 to 750 Ma that correspond to a beginning of continental rifting on the western margin of Siberian craton. Chemistry and trace element distribution are closed for host and auriferous schists and mainly showed differences in the composition initial sedimentary units. The middle negative value εNd (from -14 to -16) and very high positive value εSr (from +570 to +725) are mostly corresponded to that of upper continental crust matter. The role of synchronic granite intrusions in the studied area can be only estimated due to a generation of thermal energy and crustal fluids.
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Oxidative destruction of vulcanized by changing the dispersion composition of oxidized vulcanized
Статья научная
The aim of the present work is to study the processes of oxidative destruction of waste vulcanizates (flakes) with nitric acid. The composition of the particles of the main reaction product was determined (oxidized vulcanized). The IR spectra of hexane and acetone extracts of the oxidized vulcanizates are also presented. It was found that the rubber component of the vulcanizates undergoes deep structural changes leading to the formation of products characterized by chemical heterogeneity.
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Performance indicators of vehicle use in the transportation process
Статья научная
The article deals with the connection with the complexity of the design of the car, the diversity of some of its properties and design features, as well as their various combinations and dependences on the operating conditions and type of transportation, because it is difficult to evaluate the car by means of one general indicator. Therefore, in this article, the recommended car quality has been determined by the complex of its most indicative operational properties: capacity using mass, speed, passing ability, safety, etc.
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Performance of automatic frequency planning and optimization algorithm for cellular networks
Статья научная
Frequency planning is one of the most expensive aspects of deploying a cellular network. If a set of base stations can be deployed with minimal service and planning, the cost of both deploying and maintaining the network will decrease. To ensure that the scarce frequency is utilized to its maximum, planning and optimization are done. This is also carried out to ensure that there is high efficiency in cellular radio systems and little or minimum interference due to co-channeling. This paper focuses on coming up with an automatic way of planning and optimizing the frequency in the cellular network. The approach replaces the inefficient, inaccurate and tedious manual approach. The automatic approach simplifies work for the radio frequency (RF) engineers and also reduces the cost of operation. The automatic approach ensures that the cellular network is extensively deployed in a way that criteria of maximum quality, quantity and good coverage are met. The paper focuses on coming up with an automatic planning and optimization algorithm that minimizes the intra-system interference levels to reasonable ranges within the key performance indicators (KPIs) defined for any acceptable cellular network.
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Статья научная
He present study addresses phenology of forest vegetation based on satellite data, by analyzing the relationship between the long-term (2003-2016) series of NDVI of coniferous and deciduous tree stands and climate in the Krasnoyarskii Krai (Russia). The source data were the 8-day satellite data from MODIS (the MOD09Q1 product) and weather data from land-based weather stations. Positive trends were revealed for the average NDVI values of deciduous trees between May 1 and 16. This correlated with the trend of the accumulated air temperature (above + 5 °С) from January through May. The long-term variations in the dates of the onset of conifer seasonal growth were estimated using average NDVI values of the new shoots between May 17 and June 1: the difference between the average NDVI values of coniferous trees after the onset of the seasonal growth (June 1) and the NDVI values before the onset of the seasonal growth (May 17). Positive trends were obtained for the average NDVI values of the new shoots on coniferous trees. A tendency towards an earlier onset of the seasonal growth was obtained for a 14-year period of time.
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Photoactive oxide films and heterostructures preparation
Статья научная
The nanotechnology and molecular design should be used for the Dye Solar Cells (DSC) preparation. In this paper, we present the extraction-pyrolysis technique for the photoactive oxide TiO2, Ti2ZnO4 and conductive oxide InSnO films sensible by Ru-extract on glass substrate preparation. It is a low cost and large-scale technique for nanosize oxide films obtaining. The attempts to use the photoactive oxides TiZnO for the protection and enhancement of the Si photovoltaic cells were made. The properties of heterostructures shown that the thin oxide film on the porous Si improve the photovoltaic performance and long time stability of solar cells.
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Статья научная
Photovoltaic-thermal (PVT) panels combine solar thermal and photovoltaic technologies and generate simultaneously both heat and electricity. They can be a good variant for small domestic households to reduce their energy costs. This paper looks at the potential of these systems into the climates of Vladivostok, Russia, and Tehran, Iran. In the article, some brief background information on PVT systems and the concept of prosumers is introduced. Next, a similar PVT system is proposed for a given household consumer in Vladivostok and Tehran with the variable weather conditions corresponding to the two locations. The PVT system is modeled in TRNSYS (v18, Thermal Energy System Specialists, Madison, USA). A performance analysis is carried out in order to establish the daily instantaneous energy output and the annual energy production. The results indicate a 15-20 % better performance in Tehran compared to Vladivostok due to slightly better weather conditions, though the total efficiency of system has a better performance in Vladivostok. The system efficiency was assessed through two different methods. This study concludes that both the Russian and Iranian PVT market has a good potential for adopting the technology, especially since it is currently less mature than other leader countries in renewable energies.
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Статья научная
We discuss the procedures of data aggregation as a preprocessing stage for subsequent to regression modeling. An important feature of study is demonstration of the way how represent the aggregated data. It is proposed to use piecewise polynomial models, including spline aggregate functions. We show that the proposed approach to data aggregation can be interpreted as the frequency distribution. To study its properties density function concept is used. Applying data aggregation models as input and output variables we propose a new probability density function value linear regression model (Distributions Regression). To calculate the data aggregation and regression model we employ numerical probabilistic analysis (NPA). To demonstrate the degree of the correspondence of the proposed methods to reality, we developed a theoretical framework and considered numerical examples.
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Pilot study of isothermal crystallization of goethite from metastable synthetic pyrrhotite
Статья научная
The crystal structure and the phase composition of synthesized pyrrhotite after its endurance in the atmosphere of the Earth for 29 years at temperature about 20ºС have been studied using the methods of X-ray structural analysis. Pyrrhotite contained goethite which was absent in initial samples. The analysis of the experimental facts allows to assume that goethite originated from pyrrhotite in a metastable phase. The regularity of goethite formation depending on the percentage of troilite and also on the sulphur and iron ratio in samples has been investigated. The diagram of goethite - troilite phase ratio has been constructed. The theoretical model of phase transition of pyrrhotite into goethite is offered. Good conformity of the calculated curve of the goethite - troilite phase ratio diagram with the experimental one has been obtained. The calculations done in the offered model of secondary quantization cohere well enough with the similar calculations done within the model of a molecular field.
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Plasma gasification of coal with the extraction of valuable components of the mineral mass
Статья научная
The article presents a comprehensive plasma chemical technology for processing solid fuels, using examples of Turgai brown coal or lignite. Thermodynamic and experimental investigations of the technology were made. The technology allows producing synthesis gas from the coal organic mass and valuable components (technical silicon, ferrosilicon, aluminum, and carbon silicon) from the mineral mass. The thusly produced high-calorific synthesis gas can be used for synthesis of methanol, as a high-calorific reducing gas instead of blast-furnace coke as well as power gas for thermal power plants.
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Plasmonic antenna for bright NV centers in ultradispersed detonation diamonds
Статья научная
In this work we present a theoretical analysis of plasmon nanoantennas for a diamond cluster containing a bright NV center. The results are obtained by the numerical simulations using the discrete dipole approximation. A gold shell around the diamond core is considered as antenna. It is shown that by varying the size of the nanodiamond core and the thickness of the gold shell the position of the plasmon resonance can be tuned to the emission of a NV center. A resonator shaped as a droplet-like metal cluster is proposed. It provides the selectivity of the radiation polarization that is required for applications in quantum informatics.
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Platform independent implementation of high speed serial communication based on FPGA
Статья научная
In various embedded system applications, the high speed multi-serial communication is necessary. Various embedded systems require DSP (Digital Signal Processing) to process information & FPGA to control the peripheral devices. UART (Universal Asynchronous Receive Transmit) is designed in FPGA & connected to DSP so as to meet the real time capability of system along with compact, stable & reliable data transmission. In this paper we propose a software-implementation technique of an UART to get a platform independent UART-core for high speed serial communication in FPGA. Here the core is written in Verilog & implemented using XILINX ISE.
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Positive role of magnetic separation within processing of sideritized bauxites of Kazakhstan
Статья научная
Big amount of research has been carried out in relation to high-silicon bauxites in recent years aimed at identifying methods of raw materials benefication, improving the combined sequential Bayersintering method and developing the new method for the hydrometallurgical processing [1-3]. One option of the bauxite chemical benefication is desiliconization by alkaline solution of bauxite subjected to preliminary thermal activation. Experimental data on the leaching of initial and calcined bauxite by recycle solution indicates that the preroasting of high-siderite bauxites enables to use Bayer process with better technological parameters [4]. Roasting improves the condensability of red mud, however, considering that the operation of roasting is associated with large energy costs, alternative technological scheme of low-quality gibbsite bauxites processing from various deposits of Kazakhstan has been proposed and tested in the laboratory and pilot scale.
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Power quality improvement in off-grid renewable energy systems
Статья научная
In this paper a grid-interfacing converter system with voltage and current harmonics compensation capability is considered. The idea is to integrate the power generating functions of the converter with the power filter harmonic mitigation capabilities. The analysis of compensation characteristics of different hybrid power fi lter configurations is carried out. The control method based on adaptive digital system processing is proposed. The current detecting scheme independently controls fundamental current and harmonic distribution system currents. Computation of the harmonic compensation current is performed by the adaptive notch infinite impulse response (IIR) digital fi lter. The fi lter`s parameters are made adaptive with respect to the grid frequency fl uctuations. MATLAB/SIMULINK power system toolbox is used to simulate the proposed system. The presented simulation results confirm the effectiveness of the proposed method.
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Powers adjusting wind turbine means investigation
Статья научная
Today, wind power is the fastest-growing renewable energy source. Wind power is free, clean and endless. Furthermore, the cost of the electricity produced by wind turbines already reached the point where it is comparable with that of electricity produced by some of the conventional, fossil based power plants. However, it is still important to improve upon the technology in order to keep wind energy economically competitive with traditional and other renewable energy sources. In this paper, the idea of a variable-length blades, microdevices, and plasma jet drives are offered as a means of improving energy generation wind turbines.
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