Статьи журнала - Журнал Сибирского федерального университета. Серия: Техника и технологии
Все статьи: 1404
New methodology for designing external fencing structures energy efficient civil buildings
Статья научная
Based on the performed theoretical studies and calculations, the developed methodological foundations of designing the external enclosing structures of energy-efficient buildings based on cellular concrete with a given set of properties are presented, which are of great economic importance for construction oriented in the modern period towards the creation of energy-efficient civil facilities.
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New type of detachable contact joints for aluminium cell busbar arrangement
Статья научная
The new type of detachable contact joints (DJC) for the aluminium industry is offered. It is shown, that DJC with cylindrical split contact inserts allow to provide stability of electrotechnical characteristics of connection from -50 to + 40ºC.
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Northern technology and engineering: information support of the problem
Статья научная
The article represents databases for research information support on the problems related to providing northern regions with reliable equipment and technologies. It gives characteristics of information resources on cold regions engineering topic from foreign and Russian databases: IEEE Xplore, ScienceDirect, ASCE Library, VINITI RAS, “Scientific Sibirica”. It analyses a documentary flow “Northern engineering and technology” selected from information array “Problems of the North”, which is a constituent part of DB with current replenishment “Scientific Sibirica” generated by the Department of Scientific Bibliography of the State Public Scientific-Technological Library of the Siberian Branch of the Russian Academy of Sciences. The documentometric analysis (a kind of bibliometric one) shows the chronological, quantitative, type-species, thematic structures of Russian documents.
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Статья научная
The paper proposes a numeric-analytical method for determining the communication equations of Laplace’s transformants of dynamic functions of the universal unit of radial externally-pressurized gas bearings which movable element makes small radial oscillations in the locality in its central position. Method and obtained dependences provide links between integro-differential Laplace’s transformants of the unit such as load capacity and local input and output mass flow rates with transformants of eccentricity and gas lubricant pressure at inlet and outlet of the unit. It is shown that the local transfer functions of the unit model are rational functions of the Laplace’s transform variable and all such functions have a common denominator in the form of a polynomial of this variable. The method allows to calculate the required dynamic criterion of gas bearings containing this unit with prescribed accuracy. Founded dependences give ready formulas for calculation dynamic criteria of radial single-row or multi-row ordinary passive or active externally-pressurized gas bearings in which this unit can be used for description of radial movement of its movable element.
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Статья научная
Emissions of nitrogen oxides from coal combustion are a major environmental problem because they have been shown to contribute to the formation of acid rain and photochemical smog. Coal thermalpreparation before furnace delivery is effective method to reduce NOx emissions, shown by experiments in small-scale facilities [1]. This paper presents the mathematical model of burning thermal preparation coal. Validation of the model was carried out on laboratory-scale plant of All-Russia thermal engineering institute. Modeling of low-emissive burner with preliminary heating coal dust is made for the purpose of search of burner optimal constructions which provides low concentration of nitric oxides in the boiler. For modeling are used in-house CFD code «SigmaFlow» [2].
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Numerical modeling of tribological characteristics of fibrous polymer composite materials
Статья научная
The paper presents a numerical simulation of the contact interaction of fibrous polymer composite materials in a finite element ANSYS package and studies the friction coefficients for cells with wear of 0%, 25%, 50% and 75%. To predict the coefficient of friction of composites it was proposed to use the method of mechanics of composite materials - the method of local approximation. With the help of numerical simulation, the fields of distribution of normal stresses and contact stresses in the contact zone were obtained and the corresponding conclusions were drawn.
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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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