Журнал Сибирского федерального университета. Серия: Техника и технологии @technologies-sfu
Статьи журнала - Журнал Сибирского федерального университета. Серия: Техника и технологии
Все статьи: 1471
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.
Бесплатно
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).
Бесплатно
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.
Бесплатно
Mutual coupling enhancement in antenna array
Статья научная
Antenna arrays are very important in wireless communication networks, as they can sustain radiation direction change, with high capacity and high gain requirement. Mutual Coupling (MC) between antenna arrays has effects on some parameters, impedance, reflection coefficients, radar cross-section, and array performance. Most significantly, the MC has greatly influenced the efficiency of the antenna array. This phenomenon reduces array signal processing efficiency. To address this constraint, different approaches have been proposed in this article. The usefulness of multiple approaches lies to a major degree in implementations in which the arrays have been applied. This article is a comprehensive study for investigating MC influences on several parameters, including impedance and radiation pattern. In addition, some developed decoupling methods are outlined, receiving the Mutual Impedance Method and S-Parameter Process, including the open-circuit voltage mechanism. This can aid in contrasting the different strategies in order to allocate enough knowledge to help future research.
Бесплатно
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.
Бесплатно
Статья научная
This paper is concerned with developing and introducing into industry new technologies of producing multi-component media (emulsions, suspensions, aqueous solutions and systems) with the use of cavitation, which allows to obtain considerable positive results in heat-and-power engineering, building industry, agriculture, and other industries, sciences and engineering. Power efficiency and environmental safety of the processes based on cavitation effects have been show, promising further research is expected.
Бесплатно
Nature prerequisites for zoning of suburban area of Krasnoyarsk city
Статья научная
The suburban area is a multifunctional area that has a few problems. This area should protect the ecological city area, should solve the recreation problems of the city, should supply citizens with perishable goods, and should also have an economy and science functions for the city development. In connection with the development process of suburbanization, this territory is very important for city development. Russia’s economy is going through major transitions. These transitions are rapidly changing the relationship between cities (urban areas), countryside (rural areas) and the development, growth, and popularity of suburbia. The process of suburbanization takes place in biggest cities of Russia, including Krasnoyarsk City. The modern Krasnoyarsk with a population of about 1mln people occupies the territory of 34115 ha. This article examines the analysis of functions of suburban area and connects these functions with zoning of the suburban territory. The author analyze the nature conditions of suburban area and it connection with functional zoning of territory.
Бесплатно
Network services for active learning computer systems design
Статья научная
CDIO Initiative involves active learning in the project team. To carry out projects in the limited time needed program-methodical complexes. An example of a multi-level complex developed by COD - Conceptual Object Design, for multiple designing computer systems and automatic evaluation of resources for local installation and a network services.
Бесплатно
Статья научная
Today, it is relevant to develop a methodology for assessing the degree of deterioration of a building based on the loss of heat-shielding properties of its external enclosing structures, and hence the establishment of the physical parameters of the fences responsible for the formation of comfortable conditions in the internal environment of the premises. Based on the research carried out, the dependence of the air flow through the cell of free volume per unit time was obtained as a function of the cell diameter and the modulus of the pressure gradient. This article presents the results of the obtained mathematical model of the interaction of the building envelope with external climatic factors, taking into account the regularities of changes in the characteristics of the outdoor climate.
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
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].
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
