Журнал Сибирского федерального университета. Серия: Техника и технологии @technologies-sfu
Статьи журнала - Журнал Сибирского федерального университета. Серия: Техника и технологии
Все статьи: 1459
Directional characteristics of circular scanning aperture
Статья научная
In this paper explicit analytical expressions are derived which describe basic directional characteristics of circular scanning aperture: radiation pattern for different kinds of amplitude distribution, beamwidth, part of radiated power contained in the main lobe, directivity. Consideration is based on the theory of continuous ring radiator within the scalar approximation.
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Статья научная
The development of fast, qualitative and quantitative material characterization methods is one of the most important current issues in the field of nanosystems metrology. On this evidence it seems to be important to conduct a research on the capabilities of multimode resonance imaging mode in atomic-force microscopy (AFM) that allows broadening AFM capabilities in quality of nanonscale structures metrology and nano-object image quantitative analysis. The subject of this paper is modeling of physical phenomena that arise during the creation of such systems that describes coherent mechanic and electric phenomena in self-sensing and self-actuating cantilevers operating in multi-frequency resonance mode. The outcome of the research is represented by a virtual dynamic AFM model that allows understanding the signal generation process in AFM control and measuring circuits during sample scanning in multi-frequency mode.
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Effect of changing the symbol rate of QAM modem on the performance of 32kb/s ADPCM system
Статья научная
This paper presents three models of Quadrature Amplitude Modulation (QAM) modem operating at data rate of 16.8kb/s to be transmitted over 32kb/s Adaptive Differential Pulse Code Modulation (ADPCM) channel. These modems operate at symbol rates of 2400, 2800, and 3360 baud with associated number of bits per symbol of 7, 6, and 5 respectively. The performance of ADPCM is studied considering these modems with different constellations. The simulation results show that the performance of ADPCM degrades as the symbol rate decreases or number of bits per symbol increases. Also, the performance with circular constellation is better than rectangular one.
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Effect of neodymium and erbium on the kinetics oxidation of Zn0.5Al zinc alloy, in solid state
Статья научная
Thermogravimetrical method studied the effect of alloying additions (on 0.01÷1.0 wt%) of neodymium and erbium on the oxidation kinetics of Zn0.5Al zinc alloy in the temperature range of 523-623 K. The values of the oxidation rate of the Zn0.5Al alloy and the alloy alloyed with neodymium and erbium, have been established in solid state. The behavior of ternary alloys with the participation of neodymium and erbium at the indicated temperatures somewhat differs from the oxidation of the binary Zn0.5Al alloy. For the eutectoid Zn0.5Al alloy, as compared with the alloys alloyed with neodymium and erbium, the minimum oxidation rate was noted. The addition of 0.5 and 1.0 % Nd and Er in the zinc alloy Zn0.5Al significantly increases its oxidizability. Alloy additions (on 0.01÷0.05 %) of neodymium and erbium slightly increase the oxidizability of the eutectoid zinc alloy Zn0.5Al. During the oxidation of the studied hard alloys, protective oxides pellicle are formed ZnO, Al2O3, Nd2O3, Er2O3, ZnAl2O4.
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Effect of the carburizing layer on the morphology of chromium carbides
Статья научная
Low carbon steel substrates were face-hardened by cementing, after which thin layers of chromium were deposited electrolytically on these substrates. After deposition, the samples were exposed to isothermal annealing at a temperature of 950°C. The characterization of the thin layers was carried out by means of optical microscopy and interferometry using the Vickers micro- hardness test. The obtained results allowed establishing the phase shift kinetics (under the effect of the cementing layer) in thin layers of chromium, which are transformed into chromium carbide when passing through metastable transition phases. These transformations were due to diffusion of the carbon atoms coming from the layer of cementing, germination and growth in solid phase. This fact has been examined taking into account the annealing temperature, the lattice parameter evolution and the deposited chromium layer morphology. As to mechanical properties, it was established that the micro-hardness depends on the phase shift evolution.
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Статья научная
Slime processing at PD OAO MMC Norilsk Nickel involves oxidizing-sulphatizing roasting, calcine leaching with sulphate solution, calcine cake smelting into anodes followed by electrolytic dissolution, and a number of processes designed for accompanying elements recovery. Resulting final products are platinum-palladium (60-65 % Σ Pt+Pd) and rhodium-ruthenium (2.0-3.5 % Rh) concentrates (KP-1 and KP-2, respectively), refined silver, selenium of technical grade and tellurium. Process cycle duration, considerable work-in-process amount, a great number of operations and low efficiency of individual operations are considered to be disadvantages of the slimes processing method. We determined optimal process conditions for copper slimes calcine cake repulping with sulphate (reagents, consumption and sodium hypochlorite feed rate) offering 6-7 fold increase of Pt recovery into solution and 1,5-2,0 fold that of Pd. PGMs precipitation from resulting solutions was fount to yield precipitate with Pt and Pd content amounting up to 55 %; this makes it possible to produce it as final product. The product is then sent to a final product (KP-1 concentrate) packaging section bypassing smelting and electrolysis stages with inherent high PGMs losses, resource intensity and long duration time.
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Electrochemical method of discharged waters cleaning with of alternating current
Статья научная
High power consumption, equipment unhandiness, and need for consumable materials prevent wide introduction of electrochemical methods of water and water solutions cleaning. This article presents the results of tests of industrial discharged water cleaning applying electrochemical method and shows the mechanism of this process.
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Electronic structure of SnO 2 when doped with Sb and V
Статья научная
There was carried out theoretical and experimental investigation of the influence of Sb and V dopes on the electrophysical properties of the SnO2-based ceramic materials. Modeling was done with the help of the program package VASP within the density functional formalism. The SnO2-based ceramics was synthesized according to the standard technology at the sintering temperature 1300 ºС with different Sb dope concentrations (1 to 5 %). The material made with V dopes had a low electrical conductivity. The structure investigation showed Sb being completely dissolved in the SnO2. The calculations showed that the activation energies are Egap(SbSn47O96)= 1.19 eV and Egap(VSn47O96)= 1.33 eV. The experimental investigation showed that the increase of the stibium oxide concentration leads to the decrease of the band-gap energy from 1.33 eV to 0.75 eV. The difference between the calculated activation energy value of the Sb-doped SnO2 and that obtained from the experiments is 19 %.
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Energy and ecological aspects of coal-water slurry utilization
Статья научная
The opportunity of technological and modified lignosulphonate wastes, process water, oxygenized brown coal with high content huminic acid (to 60 %) with alkali usage as plasticizer agent in the coal-water slurry (CWS) production technological process was checked. The CWS stability scheme in alkali additives interaction was suggested. The bituminous and brown coal mixture (10: 90) CWS was investigated. The anthracite and brown coal relation is from 5 to 95. The discovered regularities demonstrated the slurry properties optimization opportunity in industrial conditions by combined changing of additive quantity and coal physical-chemical composition. The suggested CWS production technology allows solving some questions of ecological safety and resource-saving at the expense of the sources of raw materials assortment expansion. The CWS production industrial scheme on production run equipment without its modernization is developed. The combustion parameters of this fuel are shown. It is established that CW fuel combustion allows reducing the harmful emissions in atmosphere several times.
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Energy efficient dynamic bid learning model for future wireless network
Статья научная
In this paper, an energy efficient learning model for spectrum auction based on dynamic spectrum auction process is proposed. The proposed learning model is based on artificial intelligence. This paper examines and establishes the need for the users to learn their bid price based on information about the previous bids of the other users in the system. The paper shows that using Q reinforcement learning to learn about the bids of the users during the auction process helps to reduce the amount of energy consumed per file sent for the learning users. The paper went further to modify the traditional Q reinforcement learning process and combined it with Bayesian learning because of the deficiencies associated with Q reinforcement learning. This helps the exploration process to converge faster thereby, further reducing the energy consumption by the system.
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Energy efficient modular block diagram of an air heat pump heat supply system
Статья научная
The use of air source heat pumps, together with other renewable energy devices and high efficiency heating equipment, together with digital control systems, is a promising European trend that continues to grow in the face of rising costs of traditional energy carriers. The article presents a number of technical energy-saving solutions, such as a mixing chamber for HHP, built into the heat supply system and the use of a supply and exhaust ventilation system, which is based on the principle of recuperation. A digital modular-functional-structural diagram of heat generation of a coolant from the environment is proposed. Based on the energy efficiency of the circuit solution with an electric boiler, a buffer tank and a patented mixing chamber, the authors achieve a rationally controlled heat and air exchange of a combined heat pump space heating system. Automation of the joint work of rationally selected elements of the heat pump air system is one of the Smart Home technologies that improve the efficiency of heat supply, create comfortable living conditions and security due to the digitalization of the control algorithm for this system.
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Статья научная
The research represents the method of initial alignment of attitude navigation receivers that allows ensuring the required accuracy of initial alignment of attitude navigation receivers (ANR) on the customer’s objects.
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Статья научная
The purpose of this study is analysis of relationship between chlorophyll content and chlorophyll photosynthetic potential of oats and barley cultivars. For this aim we used ground remote sensing and laboratory data. Ground data were obtained at the experimental fields, located in the Krasnoyarsk region. Experiments were carried out in different seasons, under various lighting conditions with the control of plants state. Spectral measurements were done by double-beam spectroradiometer. It is installed on the mobile work platform at heights of 5 to 18 m. The study showed good correlation between chlorophyll photosynthetic potential and chlorophyll content for different oats and barley cultivars. The value of chlorophyll photosynthetic potentials is different for barley and oats cultivars during the growing season.
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Статья научная
This paper covers the results of the composition and structure evolution of nanostructured materials produced by separate electrochemical oxidation of metals (copper and aluminum). The electrolysis products after short-term and long-term aging were characterized by XRD (X-ray diffraction) and DSC (differential scanning calorimetry) analysis. There is the difference in aging of nanostructures of copper- and aluminum-compounds. Short-term aging results in the phase transformation of copper(I) oxide and the stability of aluminum oxyhydroxide (boehmite). Copper (I) oxide is oxidized to copper (II) oxide and copper carbonate hydroxide. At long-term aging the oxidation of copper (I) oxide does not completed because the Pilling-Bedworth ratio for copper (II) oxide, copper carbonate hydroxide is greater than one. The structure of all copper-containing compounds (copper (I) oxide, copper (II) oxide, copper carbonate hydroxide) is changed. It results in the increases of both the interplanar spacing and the temperature of the phase transformations. Coherent scattering region (CSR) of boehmite and copper (I) oxide are 3-4 nm and 20-30 nm, respectively, and does not change at short-term and long-term aging.
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Статья научная
In this work, welding explosion of multiple sample with its further annealing to 300 degrees is used as the method of receiving layered materials. Using this technology allows heating in the air; herewith possibility of oxygen penetration into internal material layers is eliminated. Using this technology allows heating in the air. Furthermore, pressures developed in the process of welding exposure ensure quality contact between the surfaces of plates [1].
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Exotic grains in a core from Cornwall, NY - do they have an impact source?
Статья научная
We have found seven discrete layers in a bog core from Cornwall, NY about 80 km away from the Atlantic Ocean. All but two layers contain material that is unlikely to be locally derived. In most cases, the material in the layers has been transported thousands of kilometers from its source area. Six out of the seven layers are difficult to explain except through impact processes. If all of these layers are derived from impacts that produced craters, the data imply a very high impact rate during late Holocene time. In addition, we have been able to associate two of the impact ejecta layers with dated tsunami events that span the Atlantic Ocean. If this discovery is validated by further research, it implies a much larger tsunami hazard in the Atlantic Ocean than previously reported.
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Статья научная
Presented the experience of the application method of combined rolling-extruding of metals for obtaining semi-finished products from deformed and secondary aluminum alloys on combined treatment installations. Research the structure and properties, and the possibility of obtaining hot-extruded semi-fi nished products from recycled aluminum alloy AV93.
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Статья научная
The article presents the results of experimental research and numerical simulation of the amplitude-frequency characteristics (AFC) of the voltage transmission ratio (voltage gain) |Ku| and frequency characteristics of the voltage standing wave ratio from the input (input VSWR) to three bandpass filters on the waveguide-slot membranes (WSM) with L-shaped resonance slot: to the single stage, to the three stages and to the four stages. The filter designs are given in article. The results of numerical simulation and experimental study show that in the frequency range 5,0...8,5 GHz filters provide attenuation behind the pass band up to 30 dB at the level of the introduced losses in the pass-band from 0,2 to 1,0 dB. The values of the calculated and experimental input VSWR in the filter bandwidth of pass-band are from 1,1 to 1,74 relative units (r. u.) and in the stop bands from 2 to 300 r. u. The authors believe that using of waveguide-slot membranes will significantly reduce the overall dimensions of microwave bandpass and bandstop filters in the middle of the centimeter wavelength range.
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Experimental study of temperature distribution in a cyclone-vortex furnace
Статья научная
This article describes the experience and results of experimental study of the temperature distribution in the refractory lining of the gas and liquid fuel cyclone-vortex furnace (CVF). Temperatures were measured with type K thermocouples. Most of the thermocouples are located a depth of 25 mm from the surface combustion chamber. With increasing boiler load observed decrease in temperature and increase of plating unevenness of the temperature distribution in the combustion chamber. This is due to the redistribution of heat generated between the combustion chamber and the firebox as the load increases. The results of heat transfer studies in CVF will lead to a reduction in the thickness of the lining, modernization of the CVF structure. In the future, abandon the use of refractory lining in CVF.
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Experimental study of the effective insulation of building envelopes
Статья научная
The relevance of research is caused by the fact that at present, modern standards for saving thermal energy and thermal protection of buildings are focused on the use of a very limited set of solutions to reduce energy consumption, which do not always meet the specific conditions of construction and are often very expensive. A method for studying the effective insulation of building envelopes is proposed, taking into account the relationship between structural, heating, regime parameters and economic indicators. The goal is to determine the optimal value of the insulation thickness of the heat-insulating material, taking into account the thermal energy supplied to the object. The study used methods of mathematical modeling of heat transfer, optimization problem. An experimental study is presented, showing the possibility of applying the method of technical and economic optimization of thermal insulation of building envelopes. It was determined on the basis of the mathematical model of the thermal insulation of building envelopes developed by the authors, taking into account the regulation of the supplied thermal energy. The result of the study is to reduce the cost of heat losses through building envelopes and electrical energy for the regulation of the “heating, ventilation and air conditioning” system. The conducted studies testify to the expediency of using the proposed developments, which contribute to determining the optimal thickness of wall insulation with heat-insulating material, finding the minimum reduced costs, and an advantageous choice of a method for regulating the supplied thermal energy.
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