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Naukovi visti NTUU “КPІ”. – 2016. – N 5



THE MODEM EQUIPMENT BASED ON SDR-TECHNOLOGY FOR NEW GENERATION TROPOSPHERIC STATIONS /M.E. Ilchenko, M.M. Kaidenko, S.O. Kravchuk - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. Modem equipment of tropospheric communication lines is an important component of modern means of telecommunication. The theoretical and practical aspects of choosing a preferred embodiment of modem equipment, taking into account the aggregate indicators of quality.

Objective. Presentation of features of the modem equipment construction of new generation tropospheric stations that can provide high data transfer rates with guaranteed quality of service in complex stationary and non-stationary noise inherent in tropospheric channels.

Methods. The goal is achieved by using new technical and architectural solutions to build SDR based modem equipment, spectrally efficient modulation types and coding, algorithms of effective adaptation to changing operating conditions. Feasibility of the proposed approaches to the construction of the modem hardware is fulfilled on a prototype of the equipment based on the HSMC ARRadio Daughter Card debugging modules.

Results. The features of constructing of modem equipment of troposcatter stations with high data transfer rate are provided. To reach the limiting parameters of such stations the application of modem equipment of new technical and architectural solutions, spectrally efficient modulation types (OFDM plus linear modulation) and error-correcting coding, efficient algorithms of adaptation to changing conditions of work, the SDR technology, frame structures of physical layer was proposed. The configuration variants of modem equipment in relation to the modes of operation of compact troposcatter station were proposed.

Conclusions. The proposed ways to improve the effectiveness of modem equipment allow realizing compact troposcatter radiorelay stations with a high rate of data transmission.

Keywords: software-defined radio; troposcatter station; modem; adaptation; operation modes.

ENERGETIC PARAMETERS OF RECOIL DURING EXPLOSION-MECHANICAL DRILLING /O.M. Terentiev, P.A. Gontar, A. Shukurov - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. Modern methods of destruction are spending up to 90 % of energy to prepare for extraction. Specific energy consumption reaches 120 kW·h/m3. The study proposes a new energy efficient destruction of rocks with combined explosive-mechanical loads.

Objective. Evidence of explosion-mechanical action machine’s recoil absence during explosive charges detonation.

Methods. Determination of the factors that cause machine recoil during explosion; the study of the metal jet behavior at the moment of collision with a stope; research of recoil acceleration, speed and impact energy.

Results. It is proved that the metal jet acts as a dynamic indenter directed to a stope. After the collision with a stope it "spreads" laterally and generates micro-cracks within 20 mm from the epicenter.

Conclusions. The parameters of the machine recoil (acceleration of 0.0002 m/s2; energy 0.02 J) prove the absence of its horizontal and vertical movements during the explosion-mechanical destruction of rocks.

Keywords: destruction of rocks; explosive-mechanical drilling; energy saving; combined loading; metal jet.

PROCESSING UNCERTAINTIES IN MODELING NONSTATIONARY TIME SERIES USING DECISION SUPPORT SYSTEMS /P.I. Bidyuk, O.M. Trofymchuk, O.P. Gozhyj, O.P. Bidiuk - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. Forecasting of nonlinear nonstationary time series (NNTS) is important problem in economics, marketing, industry, ecology and many other branches of science and practical activities. Successful solution of the problem requires development of modern computer based decision support systems (DSS) capable to generate reliable estimates of forecasts in conditions of uncertainty of various type and origin.

Objective. The purpose of the research is as follows: development of requirements to the modern DSS and their formal representation; analysis of uncertainty types characteristic for model building and forecasting; selection of techniques for taking into consideration of the uncertainties; and illustration of the system application to solving the problem of forecasts estimation for heteroskedastic NNTS using statistical data.

Methods. To reach the objectives stated the following methods were used: systemic approach to statistical data analysis; statistical approach to identification and taking into consideration of possible uncertainties; Kalman filtering techniques; Bayesian programming approach and statistical criteria of model adequacy and quality of forecasts.

Results. Formal description of the DSS is provided, and requirements to its development are given; the classes of mathematical methods necessary for DSS implementation are proposed; some approaches to formal taking into consideration of probabilistic, statistical and parametric uncertainties are discussed; and illustrating example of the DSS application is considered.

Conclusions. Systemic approach to DSS constructing for solving the problem of nonlinear nonstationary time series forecasting turned out to be very fruitful. Using the system proposed it is possible to take into consideration various uncertainties of probabilistic, statistical and parametric type, and to compute high quality estimates of short and medium term forecasts for NNTS. The approach proposed has good perspectives for the future improvements and enhancement.

Keywords: time series forecasting; systemic approach; probabilistic, statistical and parametric uncertainties, decision support system.

USING OF COGNITIVE AND PROBABILISTIC MODELING AT THE TASKS OF FORMING A SCENARIOS OF DEVELOPMENT OF SOCIO-ECONOMIC SYSTEMS /O.M. Terentiev, T.I. Prosyankina-Zharova, V.V. Savastiyanov - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. The complexity of the problem of choosing the direction of development of the national economy and its subsystems in conditions of uncertainty involves the use of decision support systems, which will implement the methods of analysis and forecasting of development of social-economy systems, based on an integrated approach, that takes on board a significant number of factors, both promoting and hampering the development of social-economy systems of the regions of Ukraine. The method of developing scenarios of social-economy systems with the use of cognitive and probabilistic modeling is proposed.

Objective. The aim of this work is to improve the method for scenarios planning the development of social-economy systems in the terms of structural changes.

Methods. The methods of scenarios planning, cognitive, probability modelling, SWOT-analysis, text-mining was used. A method for developing scenarios for the region's socio-economic system development in conditions of uncertainty is proposed. Its feasibility in decision support systems is substantiated.

Results. Based on the analysis of works of domestic and foreign scientists the improvement of the existing method of development of socio-economic development of regions of Ukraine is proposed. The proposed method involves the combined use of methods of scenario analysis of cognitive and probabilistic modeling. The analysis of the obtained forecasting results is carried out.

Conclusions. The advantages of applying the composition of methods of cognitive and probabilistic modeling were substantiated during elaboration scenarios of development socio-economic systems. Their use is quite perspective and will improve the system of strategic and short-term planning and forecasting, both at the state and local levels. According to the calculations a quality reliable forecast is obtained.

Keywords: scenarios; cognitive model; development of social-economy system; planning; forecasting; decision support systems.

СOGNITIVE MODELLING OF DECISION-MAKING DYNAMICS FOR UNSTABLE MODES STABILISATION IN STUDENT’S SOCIAL-EDUCATIONAL PROCESS /V.D. Romanenko, Y.L. Milyavsky - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. The paper considers social-educational process of high school student. It allows for cognitive map representation with unstable impulse transient process which is subject of research in given paper.

Objective. To build student’s cognitive map and to stabilize unstable impulse process in social-educational process described by it.

Methods. Firstly, interrelations among main concepts of subject domain were set by experts. Cognitive map was built based on this. Then stabilization algorithm for this cognitive map’s impulse process by means of direct system resources varying was developed using modal control method from automatic control theory.

Results. Simulation confirmed that it is possible to quickly stabilize student’s impulse social-educational process based on the proposed strategy. Here vertices coordinates are set at practically satisfactory values.

Conclusions. Research provided in the paper allowed finding decision-making method to stabilize dynamic system which describes student’s social-educational process.

Keywords: cognitive map; modal control; impulse process stabilization.

THE PARAMETERS OF SURFACE COLD-WORK STRENGTHENING OF PRINTING MACHINES FRICTION PARTS SURFACE MADE OF WEAR RESISTANCE COMPOSITE PARTS BASED ON NICKEL BY THIN CUBANITE GRINDING /A.P. Gavrysh, T.A. Roik, P.O. Kyrychok, O.I. Khmiliarchuk, O.S. Khlus - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. The study on the technological process of thin cubanite abrasive grinding of wear-resistant composite parts, synthesized on the base of utilized and regenerated industrial wastes of nickel alloys XH55BMTKЮ, XH50BTФKЮ, ЭП975 with additions of hard lubricant CaF2 has been carried out.

Objective. The purpose of the work is the experimental research of surface cold-work strengthening parameters by thin cubanite grinding of friction parts made of new composite materials based on nickel and identification of influence on surface cold-work strengthening parameters of part surface roughness of the cubanite instrument, its bond type, and cutting modes.

Methods. Surface treatment of printing machines wear-resistant parts based on nickel on precision grinding machine with cubatine grinding instruments with granularity 14–20 µm on Br1 bakelite resin bond at 100 % concentration of cubanite and application of thin cutting modes.

Results. It was demonstrated that granularity, the cubanite disc bond material and parameters of thin cubanite grinding essentially influence surface cold-work strengthening parameters of the machining area. The cubanite grinding discs with granularity 14–20 µm on bakelite resin bond at 100 % concentration of cubanite provide the best performance of surface cold-work strengthening level, deterioration of the second type and the surface cold-work strengthening depth that meet the high requirements at work surfaces of friction parts for printing machines.

Conclusions. It was demonstrated, that the formation of high quality friction surface parts, made of new composite materials based on nickel essentially depends on the composition of cubanite instrument (granularity, bond type), and cutting modes. The recommendations on the production were developed.

Keywords: new composite materials; instrument; friction parts; parameters of surface cold-work strengthening; cubanite discs; granulosity; bond type; thin cubanite grinding; cutting modes.

WATER DISPERSION AND DISTINCTION OF ITS LOW-HEAD EFFLUX DOWN THROUGH THE SMALL HOLE /I.I. Pukhovyi - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. Low-head dispersion of water by impact with a hard surface is suitable for organization of water freezing on vertical surfaces and on horizontal attachments with icicles. When placing a set or sets of devices for water discharge, we have to consider radiuses of drops dispersion, and when irrigation of vertical surfaces, we have to consider the width of the moistened area and the height of drops flow-up above the striking face that depends on drops’ motion trajectory.

Objective. The task of our work is the detailed study of the primary (after discharge from a hole (a nozzle)) and also of the secondary liquid atomization on drops. It is of the utmost importance to explore the heights of drops dispersion and also width and height of wetting of a vertical surface depending on distance to the center of percussion.

Methods. At irrigation of horizontal attachments, the nearby holes for water discharge are disposed at close range or in the distance, which is smaller than the peak radius of drops dispersion, taking into account reduction in irrigation density when radius increases. At irrigation of vertical attachments, the distance from the center of percussion is selected, depending on objectives to the liquid spray rate and to the initial irrigation point under the striking face, which constitutes from 60 to 150 mm for conditions of research in the higher point.

Results. As a result of pilot studies of characteristics of primary (after discharge from the small-diameter hole) and secondary (after impact with the horizontal surface) drops dispersion, we found that the maximum height of drops upsurge is increased with the altitude of their recession and is horizontal-bias away from the center of percussion. The width of the wetted vertical surface area is determined geometrically on the basis of maximum dispersion ranges in a percussion plane.

Conclusions. For the holes with the diameter of 1-2 mm in the reviewed pressure ranges (up to 350 mm w.c.), the correlation of discharge from pressure is straight-line, in contradistinction to level 0.5 for the correlation known for large-diameter holes. Dependencies to determine the range of primary drops dispersion after the discharge from a hole are obtained. Experimental data on the width of the wetted vertical surface area and on the maximum height of drops upsurge over the percussion plane are obtained.

Keywords: drops dispersion; irrigation; pressure; surface wetting.

PASSIVE METHODS OF COHERENT VORTICAL STRUCTURES CONTROL IN VORTEX CHAMBERS. PART 2. DISPERSION ANALYSIS OF EFFICIENCY/V.N. Turick, V.O. Kochin - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. Improvementof the working processes efficiency of power and technological machinery and installations of vortex type.

Objective. Statistical analysis of experimental test of the new methods of power-capacious coherent vortical structures control. Just their positive influence on processes of the transfer of mass, momentum and energy in swirling flows determines to a great extent the operating effectiveness of equipment.

Methods. Spectral valuations data of represented in the present article, part 1, methods of artificial vortical disturbances influence on power-capacious coherent formation were subjected to the more detailed numerical processing on digital foundation.

Results. Analysis of distributions of the composite swirling flow average actual velocities and the fluctuating movement intensity in characteristic area of the most power-capacious coherent vortical structure testifies to its definite stability and quasi-steady current. On the strength of this fact the detailed estimation of fluctuating movement energy balance according to determined characteristic frequency bands was carried out along the researching zone. The features of action of various eddy-generator types from the standpoint of control “stiffness” of the transfer processes were shown. Dispersion analysis confirmed the data of spectral processing of the information, put in part 1 of the article regarding to discovered phenomenon of “reverse decay of the vortices”, that is the most typical for two-dimensional eddy-generator (EG № 1).

Conclusions. Developed methods and their possible modifications offer the prospect of efficacious low-expended control on micro-level by hydromechanical, thermal and chemical processes in the cylinders of internal combustion    engines, in vortex burners, combustion chambers of rocket engines, furnaces, plasmatrons, in mixers, chemical reactors, nuclear powerplants etc.

Keywords: coherent vortical structures; control; vortex chamber; probability density distribution; vortices mutual susceptibility; dispersion; velocity fluctuations energy.

THE EFFECT OF ANNEALING ATMOSPHERE ON THE STRUCTURE AND PHASE FORMATION OF FePt/Cu/FePt FILMS COMPOSITIONS /A.Yu. Chernysh , O.V. Fihurna , I.A. Vladymyrskyi , Yu.M. Makogon  - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. FePt based nanoscale films compositions with an ordered hard magnetic L10-FePt phase provide a perspective material for ultrahigh-density magnetic recording. An ordered L10-FePt phase is formed from a disordered A1-FePt phase during high-temperature annealing or films deposition on a heated substrate. However for practical application of these materials it is necessary to reduce the formation temperature of L10-FePt phase, and also to get preferred grain orientation structure.

Objective. The investigation of the annealing atmosphere influence on the formation of structural and phase compositions in FePt films with Cu intermediate layer.

Methods. Film compositions were obtained by magnetron sputtering, structure before and after heat treatment was investigated by X-ray diffraction methods.

Results. Using X-ray phase analysis it was found that regardless of the annealing atmosphere composition of in FePt(15 nm)/Cu(15 nm)/FePt(15 nm) nanoscale film composition the phase transformation A1-FePt→L10-FePtСu starts during heat treatment at temperature of 773 K. With a rise of annealing temperature up to 973 K the ordering degree of the ternary L10-FePtCu phase increases.

Conclusions. It is established that annealing of FePt(15 nm)/Cu(15 nm)/FePt(15 nm) film compositions at 973–1073 K temperature range in Ar and N2 atmospheres leads to preferred texture formation of L10-FePtCu phase with preferred grain orientation in 001 direction. High temperature thermal treatment of FePt(15 nm)/Cu(15 nm)/FePt(15 nm) film compositions in Ar and N2 atmospheres leads to a sharp growth of grains.

Keywords: magnetic recording; nanoscale films compositions; FePt; phase transformations.

A POOLED ANALYSIS OF HEAT-RESISTANT Cr-Al STEELS /M.M. Yamshinskij, G.E. Fedorov - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. Under the conditions of rapid heating-cooling, nonuniform temperature fields occur in the volume of the part that contribute to the accumulation of thermal stresses. Such stresses may exceed the yield point of the alloy and destroy part’s material. The form of parts’ destruction depends on the properties of metal and operating conditions. A typical form of destruction is cracking. It was determined by the analysis of operation of thermal-resistant parts that the choice of alloy with high oxidation resistance is necessary, but not enough to provide the specified life of thermal-resistant items, since in thermal cycling conditions heat resistance of metal begins to appear primarily.

Objective. The aim of the work is to establish the effect of carbon and rare earth metals on heat resistance of thermal-resistant Cr-Al steels for work in extreme conditions and the study of the kinetics and mechanism of destruction of metal.

Methods. Samples of 90 mm in length and 12 mm in diameter were subjected to heat treatment in a box furnace to 1100 °C, and chilled under running water. Assessment of heat resistance was done with the appearance of thermal fatigue cracks on the side surface or at their ends. Phase composition and structure were investigated by modern X-ray diffraction and metallographic methods.

Results. The mechanism and kinetics of the destruction of cast metal under conditions of thermal cycles were determined. The selection of Cr-Al steel for work under extreme conditions should be made with regard to its mechanical, physical, physico-chemical and technological properties, as well as the design features of a particular casting.

Conclusions. To achieve high heat resistance in the conditions of high variable temperatures Cr-Al steel should comprise 25–30 % of Cr, 1.0–3.0 % of aluminum, 0.3–0.6 % of titanium, 0.2–0.4 % of C and 0 15–0.40 % of rare earth metals.

Keywords: carbon; rare earth metals; Cr-Al steel; structure; heat resistance.

THE RELATIONSHIP OF POINT SPREAD FUNCTIONS OF ABERRATION AND DIFFRACTION LIMITED LENS OF MATRIX IMAGERS /V.G. Kolobrodov, B.Yu. Pinchuk - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. Thermal imagers are widely used in many areas, but the priority is to use them for military purposes where the primary goal is focused on the identification and recognition of objects in difficult weather conditions. The quality of thermal imaging is estimated by the modulation transfer function (MTF), which is obtained by Fourier transform of the point spread function (PSF).

Objective. The aim of the paper is to get the ratio, which would have established a relationship between the PSF aberration and diffraction limited lens matrix imagers.

Methods. An approximation of the PSF in the form of a Gaussian function was proposed to consider as PSF limited lens aberration.

Results. Based on the analysis of functions of energy concentration, the relationship between the PSF for the aberration and diffraction limited lens was established. The formula, which summarizes all the formulas with correspondingly different conditionally selected levels, which determine the radius of the circle scattering PSF aberration of an optical system (AOS) was obtained.

Conclusions. Analysis of the resulting relationship for PSF aberration and diffraction-limited lens showed that produced by PSF luminance highs differ in 2 times, on condition that the radius of the circle scattering AOS is minimum. The formula for calculating the minimum radius of the circle of confusion, in which AOS is considered diffraction limited, is obtained.

Keywords: thermal imager; modulation transfer function; point spread function; radius of the circle scattering of lens.

THE APPLICATION OF ACOUSTIC METHOD FOR DIAGNOSTICS OF STRUCTURAL SHAPES STRESS CONDITION /G.S. Tymchik, M.V. Filippova, M.A. Demchenko - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. Article is dedicated to the problem of the state quantity value pressure to the structural shape constructions during the process of exploitation without method of acoustic control testing.

Objective. The aim of the paper is the improvement of the acoustic diagnostics of the shape constructions using the acoustic method of control.

Methods. The echo reflection-shadow method for the achievement of the aim of research was proposed.

Results. The acoustic spring connective coefficient was defined for the structural shape of metal constructions, that includes the density and fatness of the contact liquid, the force of pressure to the object of control, angle of the introduction of ultrasonic wave and the material of the control object with the usage the distance of neutral line of the structural shape construction, which allows improving the accurate diagnostics.

Conclusions. The experimental research on the metal with this known chemical state allows defining the acoustic pressure coefficients of the connections of the structural shape of the metal constructions. Comparative analysis was carried out theoretically due to the proposed method of the acoustic diagnostics. It showed the absolutely fault for the pressures of 10 Amp, which is not higher than 3 % from the state of material.

Keywords: structural shape construction; echo reflection shadows method; metal construction.

MATHEMATICAL MODELING OF ISOTHERMAL PLUG FLOW REACTOR WITH CONSECUTIVE REACTION TAKING INTO ACCOUNT THE CATALYST DEACTIVATION /I.D. Lucheyko - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. Mathematical modeling of continuous chemical-technological processes in non-stationary conditions of their implementation is an urgent problem. Solving specific problem numerically on a computer can only provide a formal adequacy of the model to the original. Consequently, the analytical solutions have undeniable advantages over numerical solutions. In the case of heterogeneous catalysis, deactivation of solid catalyst (Kt) takes place with a reduction of the process selectivity, which leads to economic losses. Therefore, the rational (the maximum-beneficial) catalyst lifetime Θmax>>1  is the essential part of the problem of industrial Kt selection.

Objective. The aim of this study is an analytic solution of the problem of operating mode description of the isothermal system “PFR (τL) + reaction
A1
k01, n1=1

Kt, kД1

α2A2k02, n2=1

Kt, kД2

α3A3+ Kt (kД(i))" under influence of destabilizing factor of deactivation Kt and calculation of rational time ΘmaxmaxL of its exploitation.

Methods. The modified mathematical model for the calculation of influence deactivation of Kt on the system operation mode is used. Distinctive features of the model are: reactor has a variable length at a constant flow rate and has equal initial and boundary conditions.

Results. The relative deviations | εη2|~kД1τ<<1 of yield of product A2 and εS2~kД1τ  of the selectivity for conditions of the deactivation of industrial Kt in the linear approximation analytically are calculated. It was found that the magnitudes of εη2and εS2 are determined by the relation γД0k  of the simplex γД=kД2/kД2 of rate constants of Kt deactivation and of the simplex γ0k=k01/k02 of stages rate constants.

Conclusions. It is proved that with respect to the yield of A2  the self-regulation effect (εη2=0)  of mode takes place. Nomogram for determining of 1<<Θmax<<(kД1τL)-1 by the maximum-admissible value of εдопη2max<<1 is calculated. For example, at the degree of the conversion x0=75% of reagent A1 and εдопη2max=1%, γД0k =1 ⇒ Θmax ≈1,2•103(kД1τL=10-5). The rational time Θmax of exploitation of Kt increases (approximately directly proportional) with a decrease of the simplexes relation γД0k.

Keywords: mathematical modeling; plug flow reactor; consecutive irreversible reaction; deactivation of solid catalyst; catalyst lifetime

ELECTROCHEMICAL IMPEDANCE SPECTRUM OF A LITHIUM–SULFUR–BIS(TRIFLUOROMETHANE)SULFONIMIDE LITHIUM SALT SYSTEM: MODELING AND ANALYSIS OF THE TEMPERATURE DEPENDENCE /K.D. Pershina, V.A. Sirosh, N.I. Globa - K. Naukovi visti NTUU “КPІ”. – 2016. – N 5

Background. Lithium sulfur current sources are the most promising modern power sources. But their widespread application is limited by valid methods of troubleshooting of the formation of poorly soluble film on the electrode, and on the separator surfaces.

Objective. The purpose of this paper is to apply the method of electrochemical impedance spectroscopy (EIS) for diagnosis of the parameters impacting on the electrochemical properties of Li–S current sources.

Methods. The study and modeling of the electrochemical impedance spectra of the Li–S elements with LiTFSI in tetraethylene glycol dimethyl ether electrolyte is carried out. The calculated method of the capacitance change and analysis of the mechanisms of electrochemical processes with using of the EIS method are performed.

Results. It is determined that the using of several calculated methods and models of the EIS spectra can not only diagnose the condition of the degree of discharge and temperature in the Li–S current sources, but also enables to correct the quantitative composition of the electrolyte and cathode mass.

Conclusions. The paper describes the methods of calculation EIS spectra for analyzing the impact of the Li–S current sources component composition and structural characteristics on their status. The regions of the spectrum, responsible for the various processes implementation were identified in the studied electrochemical systems. This has created the possibility to establish the particular appearance of the charge effect when heated elements discharged due to an increasing of the sulfur nano-sized particles number as a result of the discharge process in the cathode space.

Keywords: lithium; sulfur; allotropy; electrochemical impedance; sulfides; polysulfides.

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