Журнал Сибирского федерального университета. Серия: Техника и технологии @technologies-sfu
Статьи журнала - Журнал Сибирского федерального университета. Серия: Техника и технологии
Все статьи: 1459
Statistical regularities of chronology of astronautics
Статья научная
In article chronological anomaly of astronautics is described and investigated by methods of mathematical statistics. The binomial law of distribution of number of chronological coincidence is proved. It is shown, that the probability of casual occurrence of considered coincidence is rather small.
Бесплатно
Stochastic simulation of covariance matrix and power load curves in electric distribution networks
Статья научная
An algorithm of stochastic simulation of covariance matrix and nodal power load curves is developed for electric distribution networks based on factor analysis. Statistical stability of factor power load model is confirmed. Application of this model is able to identify a general regularity of nodal power changing, and to simplify the analysis of multivariate operating conditions in operational problems of electric distribution networks and their optimization.
Бесплатно
Статья научная
Work is devoted research of features of structure formation processes in the contact zone of limited solubility bimetals and alloys subjected to plastic deformation. It is established, that the plastic deformation of limited solubility metals (Al-Ti, Al-Ni), can significantly broaden the scope of their mutual solubility. The appearance of zones of local tensile and compressive stresses (curvature crystal lattice zones) leads to increased solubility, emergence of new phases and redistribution of their composition, reorientation of granular structure.
Бесплатно
Structural topological analysis of cardiac conduction system
Статья научная
In this paper the method of structural-topological analysis of cardiac conduction system based on wavelet analysis of electrocardio signal reflecting conductive network of heart topology has been considered.
Бесплатно
Статья научная
The purpose of this work was to study the chemical changes, taking place during the initial stage of the interaction of butadiene rubber and its vulcanized product with nitric acid by means of the differential IR spectroscopy. Thus some mechanistic knowledge, associated with the complex nature of this process could be obtained.
Бесплатно
Study of alternative methods for preparing the pitch binder for the anode paste
Статья научная
Aluminium smelting industry is the biggest consumer of coal tar pitch, but the use of pitch causes numerous problems because of some economic and environmental factors. Russia’s growing defi cit is covered by import deliveries, which cannot guarantee a secure future. At the same time stricter environmental sanctions related to the use of coal tar pitch as a source of cancer-inducing emissions, are supporting the search for alternative raw materials and the development of new pitch binder production techniques. Given that the known reserves of bituminous coal will be sufficient to last for 230 years at the current production rates as opposed to the oil reserves that will be enough for 40 years only, it becomes obvious that the development of a pitch binder production technique based on thermochemical processing of coals is a promising direction to follow. Investigations were carried out to dissolve coals thermo-chemically in various organic solvents at varying levels of temperature, pressure, and reaction times. It was shown how mechanic activation and ultrasonic exposure affect the degree of organic coal mass extraction. The methods of vacuum and atmospheric distillation were used to produce pitch products from coal extracts. It was demonstrated that the use of coking additives, including nano-modified carbon, helps improve the application properties of pitch products. Large-sized samples of coal tar pitch were used to produce trial lots of anode paste for Soederberg anodes.
Бесплатно
Статья научная
Technology for making electrical aluminum alloys with different contents of rare-earth metals and nickel was developed. Cast and deformed semi-finished products made of new alloys were obtained as a result of experimental studies. The structure and mechanical properties of metal were studied as well as electrical resistivity measurements of rods and wires were carried out. The effect of nickel and rare-earth metals on these characteristics was found out and alloy compositions with the most favorable combination of strength and electrical properties were determined.
Бесплатно
Study on long-term tempering on the microstructure of creep strength enhanced ferritic P92 steel
Статья научная
Present paper deal with the studies of effect of long term heating on the microstructure and mechanical properties of creep strength enhanced Cr-Mo P92 steel. Such steels are used in supercritical power plant boilers where continuous operating temperature and pressure can be as high as 650 0C and 300 bar respectively. The P92 specimens were thermally exposed at temperature of 650 0C for duration of varying from 1000 to 3000 hours. Tensile fracture and impact toughness fracture surfaces were studied by using scanning electron microscope. The fracture surface of P92 impact toughness specimen exhibited both inter lath-decohesion and ductile dimple tearing. The various phases that formed in the tempered P92 steel were analyzed by X-ray diffraction. In XRD analysis of tempered P92 it was observed that amount of precipitates increased as compared to untemperedcondition. After tempering time of 1440 h, some new precipitates such as NbC, NbCrN were also observed.
Бесплатно
Supercapacitor as a buffer electrical source for induction motor
Статья научная
Mathematical substitutions in the equations and the used methods have shown the adequacy and correctness of their use. Analysis of the data, obtained from simulation modeling of the developed model, showed small discrepancies with the standard block from the Simulink library. The use of the obtained mathematical equations, as well as the model assembled in Matlab Simulink, will make it possible to qualitatively evaluate the operation of an induction drive in statics and dynamics. This model will be used in future research, including the creation of a buffer power source based on a supercapacitor for an induction electric drive.
Бесплатно
Статья научная
In this paper, we analyzed the vehicle’s driving modes and opted for the idle mode to save fuel. The synergy of the vehicle with the traffic light depends on many factors and has been studied on the example of the information model of the “Intelligent start-stop system”. A vehicle with an “intelligent start-stop system” was saved 8.25 % of fuel during 100 km in urban conditions. In addition, emissions of harmful gases into the environment have been minimized. It was found that an average of 132 liters of fuel was saved when one vehicle traveled 20,000 km per year. Moreover, the idling time of the vehicle’s engine was characterized by a reduction of 28-32 % in 100 km of the total test distance. Also included are the concepts of order parameter and flexible parameter on the principles of synergetic by using intelligent transport systems in the local condition.
Бесплатно
Synergy nanostructuring carbon materials based on cavitation technologies
Статья научная
The purpose of the present paper is to obtain new physical properties and to expand a range of operational properties of various carbon-blacks by using hydrodynamic and thermophysic effects of cavitation. After the cavitation experiment the wood carbon-black has in part gained some properties of nanocomposites among which there are fullereniferous and diamond-bearing carbon-blacks. In this case cavitationally processed wood carbon-blacks can be as an efficient modifying additive in lubricants, etc
Бесплатно
Synthesis of Ca4GdO(BO3)3 single crystals using Czochralski method
Статья научная
The oxoborate Ca4GdO(BO3)3 (GdCOB) is a potential material for advanced industrial applications because of its optical and electric properties. High quality single crystals of GdCOB have been grown from a melt using the Czochralski method. Single crystals of laboratory scale are of good optical quality showing no macroscopic defects like cracks, inclusions or discolouration. Crystals in [001] direction reveal regular growth, whereas crystals in [010] are of asymmetric shape but show less difficulties during the growth process.
Бесплатно
Synthetic fuel production: thermal behavior of lemon and orange peels composite fuel diesel
Статья научная
This study aimed to investigate the thermal combustion behavior of lemon peel powder, LPP and orange peel powder, OPP composite fuel diesel. The pyrolysis experiments of the diesel/ citrus composite fuel were conducted in combustion chamber. The results showed that the citrus/diesel composite fuel sustains its combustion properties at 30 % of the added citrus peels powder,. The results showed that calorific values of diesel containing 30 % LPP or 15 % LPP + 15 % OPP were very close to that of the pure diesel. The maximum calorific values were obtained at α = 0.85, 0.80 and 0.90 for 30 % OPP, 30 % LPP and 15 % OPP + 15 % LPP composite fuels respectively.
Бесплатно
Systems of automated exploration of radio-technical systems of the aviation flights service
Статья научная
There is a review of the way of training and retraining of radio-technical systems operators by using system of automated exploration, which is able to identify and manage the individual training program.
Бесплатно
Статья научная
The use of the newest methods and technologies of airborne laser location, high resolution digital photography and the global positioning satellite systems, provides principally new opportunities for remote sensing monitoring and inventory of forest resources. High efficiency of laser location (more than 200 thousand pulses/measurements per second) in combination with centimeter spatial resolution of digital aerial photography, high (about 10-15 cm) accuracy for coordinate definition of trees and tree stands morphostructural parameters by satellite geopositioning systems, as well as three-dimensional visualization of the remote sensing data at geoinformation systems, allows to developing effective algorithms for research of forest resources structure and dynamics, guaranteeing a real time automatic extraction of forest inventory parameters. Development and application of such high-end technologies to aerospace forest monitoring is critical and essential for boreal zone and, in particular, for regions of Siberia, where traditional approaches of forest inventory to be used today are not effective, do not provide required accuracy and are highly timeand funds consuming.
Бесплатно
Telemetry, command and ranging system of geo spacecraft
Статья научная
The article describes the telemetry, command and ranging system of GEO spacecraft. It addresses RF signals passage in ground-to-spacecraft path. Results of RF link budget calculations are presented. The article also addresses unaccountable parameters of using onboard and ground equipment having performances required by the link budget. System operation in ranging mode is described, as well as the existing problems of its usage. Prospects of existing disadvantages handling and system performance improvement were given.
Бесплатно
Статья научная
The Chiemgau strewn field in the Alpine Foreland discovered in the early new millennium comprises more than 80 mostly rimmed craters in a roughly elliptically shaped area with axes of about 60 km and 30 km. The crater diameters range between a few meters and a few hundred meters. Geologically, the craters occur in Pleistocene moraine and fluvio-glacial sediments. The craters and surrounding areas so far investigated in more detail are featuring heavy deformations of the Quaternary cobbles and boulders, abundant fused rock material (impact melt rocks and various glasses), shock-metamorphic effects, and geophysical anomalies. The impact is substantiated by the abundant occurrence of metallic, glass and carbon spherules, accretionary lapilli, and of strange matter in the form of iron silicides like gupeiite and xifengite, and various carbides like, e.g., moissanite SiC. The hitherto established largest crater of the strewn field is Lake Tüttensee exhibiting an 8 m-height rim wall, a rim-to-rim diameter of about 600 m, a depth of roughly 30 m and an extensive ejecta blanket. Physical and archeological dating confine the impact event to have happened most probably between 1300 and 300 B.C. The impactor is suggested to have been a low-density disintegrated, loosely bound asteroid or a disintegrated comet in order to account for the extensive strewn field.
Бесплатно
The GaN era has arrived in Satcom power amplifiers
Статья научная
In this paper features, characteristics and comparisons of gallium nitride high electron mobility transistors (GaNHEMTs) power amplifiers are considered.Maximum operating temperature widespread now, gallium arsenide GaAs transistors is 175 o C. They are inferior to the transistors based on gallium nitride GaN, and keep steadily working frequency characteristics at operating temperatures up to 250 0 C. This greatly reduces the problem of heat removal. These transistors operate at voltages up to 100 V against the maximum of 20 V for GaAs transistors at equivalent power output. Therefore, GaN transistors and power amplifiers, they are particularly relevant for applications in space exploration. In Paradise Datacom (USA) designed power amplifiers in different ranges of frequencies with a power output of up to 50 to 750 watts.
Бесплатно
The Stefan problem solution by the moving boundary conjugate equation
Статья научная
The conjugate equation, describing intensity of phase transformation of a substance on the moving boundary, is used in the Stefan problem instead of the traditionally applied boundary condition of the fourth type (Stefan condition). At the numerical solution of the problem on the one hand the conjugate equation allows to carry out the shock-capturing method without reorganization of grid areas, on the other hand - accurately trace the position of the moving boundary. The estimation of adequacy of the wet ground layer freezing process mathematical modeling in the new statement is carried out to the real process.
Бесплатно
The ability of quantum dots formation in thin nanostructured amorphous films
Статья научная
In the last years an interest in field of quantum dots devices creating has been increased. In this work the nanocrystallite with Frank-Kasper structure was examined as the quantum dot in amorphous film. An ability to create all-inorganic Quantum Dots Light Emission Device may be considered for Tb 30 Fe 70, Co 80 C 20, Fe 86 Mn 13 C and Co 50 Pd 50 films. The self-organisation of atomic structure in Tb 30 Fe 70, Co 80 C 20, Fe 86 Mn 13 C and Co 50 Pd 50 films, which possess large values of perpendicular magnetic anisotropy (PMA) constant (K ⊥ ~ 10 6 erg/cm 3 ), were investigated by methods of electron diffraction and transmission electron microscopy, including the method of bend contours. The crystallization of the films proceeds in an explosive way forming different dissipative structures from initial nanocrystalline state. In previous works [2, 3] it was shown that after crystallization (Т ann ~ 260-330 °C) the atomic structures of Tb 30 Fe 70, Co 80 C 20, Fe 86 Mn 13 C and Co 50 Pd 50 films are tetrahedrally close-packed Frank-Kasper structures. In this work the structural model of thin film at mesoscale and its correlation with magnetic and optical properties is proposed.
Бесплатно
