Статьи журнала - Журнал Сибирского федерального университета. Серия: Техника и технологии
Все статьи: 1424
Статья научная
The aluminum industry is constantly looking at reducing the production cost. During the last three decades it has mainly been achieved by the economy of scale consisting in increasing the cell dimensions allowing for higher current and therefore increasing the plant production and productivity. This paper presents under which conditions a step change can be achieved without increasing the shell dimensions. The design of a cell of the future is discussed in term of voltage distribution, heat loss, energy saving, productivity and environmental consequences.
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Статья научная
An auction based bid learning process for cognitive radio networks, where the users and the service providers are learning about each other to maximise each other’s utility is examined. A game model is formulated to allow players to learn depending on their priority. This enables users to learn different parameters such as the best offered bid price and the appropriate time to participate in the auction process. The performance of the system is examined based on the developed utility function. The results show that the blocking probability, utility function and the energy consumed is better with the learning users when compared to the non-learning users. Results also show that provided learning is taking place in the system, Nash Equilibrium can be established.
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Статья научная
The relevance of the study is due to the development herein of a model for reliability optimization of stand-alone power systems with wind turbines and electrochemical power storage devices, with special emphasis within this model put on the specifics of power equipment operation. The key feature of the model developed is that it enables us to factor in the requirements to be met by the equipment as arising from the considerations of dynamic stability of the stand-alone system. When simulating battery storage operating modes, the charge-discharge limits as well as the remaining charge in the storage are taken into account. Thus, the reduction of the total number of considered mixes of the equipment being commissioned is achieved, the computational efficiency of the reliability optimization method is increased, while the validity of modeling results is improved. Development of methods for optimization of reliability of stand-alone electric power systems with wind turbine installations and electrochemical power storage devices while meeting requirements for electrodynamic stability. A stand-alone power system that is assumed to be located in the coastal area of Lake Baikal in the Kabansky State Nature Reserve, Republic of Buryatia, Russia, serves as the object of the study. Calculations are based on multiple simulation of modes of operation of the electric power system by means of the Monte Carlo method. The values of random variables are modeled as per specified laws of distribution and fault rate indicators of power equipment. Modeling of power generation at wind turbines is based on a detailed analysis of real-life weather data (average hourly wind speed, air density and humidity). The method of reliability optimization of stand-alone power systems with wind turbines and electrochemical energy storage devices was developed so as to take into account the requirements to be met by electric power equipment in terms of dynamic stability. The optimization criterion is the minimum expected value of the cost of produced electricity. Power redundanct and energy storage devices are used as means of reliability assurance. The results of calculations attest to the fact that for the natural and climatic zone under consideration, the use of vertical axis wind turbines in a stand-alone power system proves more efficient than the use of horizontal axis wind turbines.
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A simple method for determination of switched capacitor bank in power distribution systems
Статья научная
This paper proposes an efficient and novel technique for assessment of the direction of switched capacitor bank as well as estimating its distance from the monitoring location in real distribution systems. At first, the proposed method determines the direction of switched capacitor banks based on the slope of the voltage and current space vectors immediately after the capacitor switching instant. Afterward, the exact location of switched capacitor from the monitoring location is determined by estimating the feeder line inductance using first sample magnitude of voltage and current space vector after the switching instant. The discrete wavelet transform (DWT) is also used to detect the exact instant of switching as well as the exact values of voltage and current caused by switching. In this paper, the capabilities of the proposed method are evaluated in various state of switching (normal, Back-To-Back), presence of stochastic nonlinear load and different sampling rate. The effectiveness of the proposed technique is demonstrated with system data obtained from IEEE-13 bus feeders modelled in PSCAD/EMTDC. Simulation results demonstrate the validity and effectiveness of the proposed method considering accepTable error in locating the switched capacitor bank in distribution systems.
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A study of ozone anomaly of 2011 in the Northern hemisphere based on Aura satellite data
Статья научная
In this work we have studied the appearance of analogue of the Antarctic ozone hole in the Northern hemisphere in March 2011. Possible reasons of this phenomenon were the low temperature in the polar region and intense solar flares. The solar activity led to changes in the atmospheric circulation. As a result, in the stratosphere for a while have any rotating circumpolar vortex in the form of a ring in mid-latitudes and low ozone content in the polar region. Our studies revealed a redistribution of ozone mass between the inner and outer part of the vortex with decreasing the total ozone content in the inner part and increases in the outer. A model of the formation of the circumpolar vortex based on atmospheric physics is proposed.
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Abnormal geophysical events in the northern hemisphere in 2010 and 2011
Статья научная
Based on ATOVS satellite data, temperature-pressure vertical profiles at different levels have been constructed for the epicenter of the Japan earthquake that occurred on March 11, 2011 for the “undisturbed” and seismically disturbed atmosphere (December 2010 - January-April 2011). In the undisturbed atmosphere over the focal zone, the coefficient of correlation between the time series of the temperature at levels of 200 gPa and 450 gPa was positive, reaching 0.4-0.6; in the disturbed atmosphere, there were intensive internal gravity waves, and the correlation coefficient was negative, reaching -0.86. The large wave in the atmosphere observed over the focal zone before the earthquake could have triggered it. A rare event occurred almost simultaneously with the earthquake: an ozone anomaly similar to the Antarctic ozone hole was formed in the Northern Hemisphere between March 5 and April 4, 2011. That event was preceded by a dramatic temperature drop in the lower stratosphere. In 2010, Europe experienced an unprecedented hot summer, and the winter of 2010-2011 was exceptionally cold. Those events could have a common cause. That could be an oil spill in the Gulf of Mexico in spring-summer of 2010, which changed the direction of the Gulf Stream, leading to changes in atmospheric circulation and generation of intensive atmospheric waves.
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Abnormal phenomena in the tropical part of the world ocean according to MODIS-Aqua satellite data
Статья научная
The work analyzes monthly data from the MODIS-Aqua satellite scanner on the temperature of the surface layer of water with a resolution of 4320×2160 (9 km at the equator) for 2002-2021, obtained from the Ocean Color Data website (https://oceandata.sci.gsfc.nasa.gov/MODIS-Aqua/Mapped/ Monthly/9km/). It was shown that the degree of influence of changes in ocean surface temperature on the atmosphere depends not only on the absolute values of temperature changes, but also on the surface area on which these changes occur. It was revealed that starting from the end of 2009 - beginning of 2010, the climate system of the tropical zone was destabilized, and reliably positive temperature trends began to prevail over most of the ocean surface in the tropics. At the same time, in the circulation belts of temperate latitudes, processes occur that are not synchronous either with the processes in the tropics or with each other. It was noted that zones with predominant warming or cooling are sometimes located nearby on the scale of the World Ocean, practically not separated by buffer zones. This could destabilize the ocean-atmosphere system. It was revealed that the predominance of warming processes in the Gulf Stream does not lead to a corresponding predominance of warming processes in the North Atlantic Current. The opposite is observed.
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About safety during landing aircraft of the helicopter type on unprepared ground
Статья научная
In the article the peculiarities landing a helicopter on a snowy (dusty) area and analysis the security when boarding an aircraft of the helicopter type on unprepared ground. Conditions insufficient visibility when landing in this way are one of the key problems. Since when landing on snow-covered or dry ground because the air jet from the rotor of the helicopter rises solid suspension, which critically reduces the horizontal and vertical visibility and can lead to an incorrect assessment by the crew the spatial position of the helicopter relative to the ground, in addition, unnoticed can remain obstacles in the landing zone (large stones, movable and stationary objects). In addition, when there is insufficient light or adverse weather conditions in the landing zone can be buildings, structures, masts power lines, trees, bushes, etc. Security analysis showed that the aircraft landing helicopters on unprepared ground is a serious problem. The solutions in the field synthetic vision technologies, for the safe landing of the helicopter, which allow to form a three-dimensional image the landing zone through a snow or dusty vortex, lidar (laser location), W-band radars and other developments, are outlined. The materials the article are practical value to specialists dealing with the issues of helicopter landing in remote forest, mountainous areas, the Arctic zone, etc.
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Статья научная
In article the comparative analysis of differential and integrated consideration of thermodynamic process is carried out. It is shown that use of the rule of replacement of variables of integration leads to correct output of main thermodynamic functions (an enthalpy, Helmholtz's function and Gibbs's function). It occurs through integrated consideration of thermodynamic process when parameters change in fi nal (limited) intervals. It is established that Integrated consideration of the law of energy conservation in general view for the moving fi nal volume of liquid or gas leads to «expanded» option of formula for the fi rst law of thermodynamics. At the same time the equations recorded in differential form taking into account different types of technical work. Communications between the work of pushing through of some volume of gas and work connected with pressure at expansion of gas volume are shown.
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Статья научная
The theoretical basis has been developed and the idea of practical production and testing the semiconductor electric generator (thermobattery) of a new type acting on the basis of a metal - semiconductor system has been offered. It is shown that the thermobattery will work on the basis of the use of a bulk thermogradient effect. Such effect allows to gain a sufficient level of generated power from one unit of the whole volume of a semiconductor material. When using the semiconductor thermobattery together with solar and wind electric generators, it is possible to simplify significantly constructional and technological features of these installations.
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Статья научная
This paper investigates noise-immunity of accelerated phase-lock-loop frequency control algorithms of user equipment in perspective ground-based radio navigation systems. Three algorithms of accelerated phase-lock-loop frequency control are suggested and described. Statistic simulations of signal processing in involved system are given.
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Access matrix as a passive element in the protection of information resources
Статья научная
In this work the author considers a problem of management of access to information resources of the enterprises. Formulates the purposes of a control system of access. Defines interrelation of the purposes of information security and available threats of safety. Suggests to use an access matrix as a passive element of protection of information resources. Formulates tasks which need to be solved in any control system of access. Sets a task of a redundancy exception when carrying out measures of information resources protection. Offers a formation technique of an access matrix. Describes procedure of information categorization, risk groups identification, formation of access profi les, fi xing of access rights in organization regulating documents.
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Acoustic control method of quality characteristics of new transformer oil
Статья научная
Power transformers are the most expensive and strategically important components of any power generation and transmission system. Diagnostics methods result from the necessity to provide the operational reliability of power equipment and extend its operation time. Acoustic method is one of the perspective methods to determine transformer oil quality. In comparison with standard methods the acoustic method have follow important advantages: low labor intensity, need lack of the difficult expensive equipment, carrying out researches in vitro frames and high qualification of researches. This study represents results of impurity influence investigation (water and cellulose) on an acoustic range of new transformer oil.
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Статья научная
Was proposed a device for obtaining deformed semi-finished products from chip of aluminum alloys with use combined methods of treatment. Carried experiments to obtain rods and receipted data about their mechanical properties.
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Adaptive control system for automated honeycomb filler cutter
Статья научная
This article presents the results of control system development оf an automated complex for cutting honeycomb or cellular filler, which consists of several modules performed on various software and hardware platforms and combined into a single system. On the control computer, the following are implemented: an interface module, a planning and control module written in the C ++, and a machine vision module written in the Python. The KUKA controller has a module for communication with a computer and a movement module written using the Kuka Robot Language. The interface module is required to interact with the operator, the planning and control module, and the robot information exchange module. The planning and control module performs the functions of generating sequence of elementary operations and moving points, compiling control programs and executing them. The machine vision module, using a machine vision camera, takes a series of images of the workpiece, by which the boundaries of the workpiece are identified, the edges of the cellular filler are recognized, and the coordinates of the optimal cut points are calculated.
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Статья научная
This paper reports on the results of the investigation of fly ashes from pulverized combustion of coals of two ranks, i.e., the B2 (sub C) rank, which is taken from Fields 1−4 of the electrostatic precipitators at the BSDPS -1 (the Bfa series), and the T (sa) rank, which is taken from Fields 1 and 2 of the electrostatic precipitators at the MPP-22 (the Mfa series). It has been shown that fly ashes of the Bfa series have a lower bulk density and a higher dispersity and a unimodal particle size distribution. The size of particles increases along the gas-and-dust flow, in particular from the Field 1 to the Field 2 of the electrostatic precipitators. Fly ashes of the Mfa series are characterized by a higher density, a substantially lower dispersity, a bimodal particle size distribution and have rather close size characteristics for ashes from the Fields 1 and 2 of the electrostatic precipitators. The use of the aerodynamic separation has made it possible to obtain three products from fly ashes of both series which differ significantly in the bulk density and size of particles. Combination of selective sampling and aerodynamic separation of fly ashes from pulverized combustion of coals are promising techniques for manufacturing ash products with a controlled density and dispersity.
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Aluminum busbar connection parts of the cell «flexible cathode descent – cathode bus»
Статья научная
In the given article we present our results of research of aluminum joint parts of «cathodic flexible swith a cathode bus». Basing on the theoretical analysis and experimental researches, we present the method of molding of joint assembles in the casting mould, with an overheated fusion. The suggested method let us produce a high-quality junction without loss of electrolysers'series productivity and it also allows decreasing the operational expenditures.
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An application of CO2 as a refrigerant for medium temperature heat pumps
Статья научная
This paper presents the energetic and exergetic analysis of a transcritical carbon dioxide based heat pump cycle for heating. Recycled water (tw=25…40 °C) of food production enterprises is taken into account as a source of low potential heat. The theoretical and real CO2 trans-critical cycles were analysed. Parameters, which characterize cycles from energy and exergy point of view were obtained. The exergy flow diagram (Grassmann diagram) shows that all the components except the internal heat exchanger contribute significantly to the irreversibilities of the system.
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An improved multi-objective BPSO-based method for radial distribution networks reconfiguration
Статья научная
The present paper will introduce an improved BPSO algorithm for radial distribution networks reconfiguration. In this regard PSO algorithm has extensively been used in many of the previous literatures; however, here a new method will be introduced in order to update swarm position which is not only simple and fast but also has high accuracy. The objective function has four weighted components representing load balancing, total losses of network, voltage deviation and system reliability. The test network is a standard distribution system with 3 feeder and 16 switches. Accuracy and speed of proposed method are compared with three other well-known algorithms to ensure its efficiency.
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Analysis of the Younger Dryas impact layer
Статья научная
We have uncovered a thin layer of magnetic grains and microspherules, carbon spherules, and glass-like carbon at nine sites across North America, a site in Belgium, and throughout the rims of 16 Carolina Bays. It is consistent with the ejecta layer from an impact event and has been dated to 12.9 ka BP coinciding with the onset of Younger Dryas (YD) cooling and widespread megafaunal extinctions in North America. At many locations the impact layer is directly below a black mat marking the sudden disappearance of the megafauna and Clovis people. The distribution pattern of the Younger Dryas boundary (YDB) ejecta layer is consistent with an impact near the Great Lakes that deposited terrestrial-like ejecta near the impact site and unusual, titanium-rich projectile-like ejecta further away. High water content associated with the ejecta, up to 28 at. % hydrogen (H), suggests the impact occurred over the Laurentide Ice Sheet. YDB microspherules and magnetic grains are highly enriched in TiO2. Magnetic grains from several sites are enriched in iridium (Ir), up to 117 ppb. The TiO2/FeO, K/Th, TiO2/Zr, Al2O3/FeO+MgO, CaO/Al2O3, REE/ chondrite, FeO/MnO ratios and SiO2, Na2O, K2O, Cr2O3, Ni, Co, U, Th and other trace element abundances are inconsistent with all terrestrial and extraterrestrial (ET) sources except for KREEP, a lunar igneous rock rich in potassium (K), rare-earth elements (REE), phosphorus (P), and other incompatible elements including U and Th. Normal Fe, Ti, and 238U/235U isotopic abundances were found in the magnetic grains, but 234U was enriched over equilibrium values by 50 % in Murray Springs and by 130 % in Belgium. 40K abundance is enriched by up to 100 % in YDB sediments and Clovis chert artifacts. Highly vesicular carbon spherules containing nanodiamonds, glass-like carbon, charcoal and soot found in large quantities in the YDB layer are consistent with an impact followed by intense burning. Four holes in the Great Lakes, some deeper than Death Valley, are proposed as possible craters produced by the airburst breakup of a loosely aggregated projectile.
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