ANALYSIS OF THE PRODUCTIVITY FOR ANTI-INTERFERENCE DIGITAL DATA TRANSMISSION SYSTEMS /L.O Uryvsky., A.V. Moshynska, S.M. Vergun - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. Efficient use of energy and frequency resource of telecommunications channels is needed.
Objective. The main objective is favor of a discrete communication channel productivity analysis through the identification of behavior reliability patterns of the demodulated multiposition signal manipulation by using redundant error-correcting codes.
Methods. Estimation of capacity and productivity extremum search is carried out in a gradual increase in the symbol rate. Potential noise immunity given estimated error probability value in the telecommunications channel with white noise. The error probability is achieved by correcting the reliability of the demodulator output using the error-correcting code.
Results. Analysis of capacity and productivity without coding, and with coding showed the extremum in the respective energy condition in the channel. At the same time at the point of extremum signals QAM-16 are more productive than the signals QAM-64. This demonstrates the rationality of using signals QAM-64 in wireless systems (e.g., LTE), that are useful to apply in a wide area wireless systems (e.g., UMTS).
Conclusions. Efficient use of energy resources and frequency of communication channels occurs at the point of extremum performance in well-defined values of the transfer rate. If the maximum is to the left of it is advisable to increase the symbol rate, and if the maximum is to the right the signal energy can be reduced.
Keywords: channel capacity; productivity; error probability; multiposition signals; productivity extremum.
THERMODYNAMIC EFFICIENCY OF HEAT PUMP AIR CONDITIONING SYSTEM WITH USING MIXING CHAMBER IN THE CLOSED POOL ON A HOT SEASON /M.K Bezrodny., D.S Kutra., I.V. Serhienko - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. Removal of a large amount of moisture entering the premises as a result of the evaporation, and temperature and humidity maintenance in the room of the pool is the main problem, which should effectively address heat pump air handling system.
Objective. Objective is the thermodynamic analysis of heat pump air conditioning scheme for the indoor pool on a hot period of the year depending on the parameters of the system and the outside air. The scheme provides for the mixing chamber mounting before, and then after the heat pump.
Methods. The mathematical model of heat pump air conditioning system was built, implementation of which was conducted by numerical method of successive approximations.
Results. The scheme from mixing chamber to the heat pump is characterized by relatively low values of the scheme performance coefficient, due to the relatively high heat load of the heat pump evaporator; the increase of the recycling rate and a significant decrease in the proportion of fresh supply air contributes to the preservation of cold air in the system and increases the coefficient of the entire heat pump air scheme.
Conclusions. Pool heat pump air conditioning system with the recirculation of exhaust air and the mixing chamber after the heat pump in warm or hot season has the highest thermodynamic efficiency by the values of the coefficient of the whole circuit, and the working range of changes in temperature and relative humidity of the outside air.
Keywords: heat pump; swimming pool; air conditioning; coefficient of performance.
THE METHOD OF CONSTRUCTION SCORING CARDS USING SAS PLATFORM /S.A Bakun., P.I. Bidyuk - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. Development of effective methods for evaluating solvency of individuals and risk of banks in providing consumer loans.
Objective. Determining of the mechanisms for implementation of scoring models in the form of scoring cards. Analysis of the possibility of using scoring cards as a tool for credit risk management.
Methods. Construction of scoring cards and preliminary analysis of input data using specialized component of the SAS Enterprise Miner.
Results. The main stages of scoring cards development were considered. The scoring card was constructed that is based on actual statistical data on granting of the consumer loans. The research also presents comparative analysis of the scoring cards with other statistical methods of subjects classification.
Conclusions. It was established in this study that the scoring cards have better forecasting ability than other statistical methods such as decision trees, neural networks and logistic regression. The format of development the forecasting models in the form of scoring cards is the easiest for interpreting. However, application of this method requires considerable investments as well as continuous updating and renewal of credit histories for borrowers.
Keywords: risk management; data mining; credit scoring; scoring card; logistic regression; classification quality.
STRUCTURE MODELING OF BANKNOTE PAPER SURFACE BASED ON THE THEORY OF FRACTALS /T.Yu Kyrychok., T.Ye Klymenko., O.V. Rybak - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. The article describes the experimental study of the structure of the paper surface.
Objective. The surface structure modeling of printed and unprinted banknote paper using fractal theory. Calculation of the main parameters describing the macro- and microstructure of the banknote paper surface within and beyond water marks.
Methods. A method for studying the structure of the surface paper based on the theory of fractals is used. This method is based on profilograms analysis obtained by contact and optical profilometry.
Results. The approximate method of measuring the fractal dimension of arbitrary shape was determined Si• hiD≈ c, where c – some constant, and D – fractal dimension figure. Function of the surface paper sheet was received f(h)≈L•c•h -(1+Dnp) Determined the fractal dimension D=1+Dnp, and amplitude coefficient of the surface of the paper S=Cη(2D-3)τ(4-2D). Graphical model structure of the surface paper on the basis fractal dimension and amplitude coefficient was constructed.
Conclusions. A method studying the structure of the paper surface based on the theory of fractals was developed. This method is based on analysis of profilograms obtained by contact and optical profilometry. A mathematical model of the surface of unprinted and printed banknote paper was developed. Algorithm and software to determine the fractal dimension and the amplitude coefficient of the microstructure of the unprinted and printed paper was developed. The value of the fractal dimension and the amplitude coefficient of the surface of the banknote paper was obtained.
Keywords: paper with water marks; surface structure of paper; theory of fractals; fractal dimension; amplitude coefficient; mathematical model of the surface; profilometry.
APPLICATION OF TYPE-2 MEMBERSHIP FUNCTIONS IN FUZZY LOGIC SYSTEMS /N.R. Kondratenko - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. Developing decision making models for problems, that are not easily formalized, and which operate the expert information, became possible by utilizing the capabilities of fuzzy sets theory and building fuzzy logic systems. Use of fuzzy sets theory techniques for knowledge formalization automatically results in the researcher having to select the type of fuzzy sets used for constructing membership functions, as well as the fuzzy model, that would fit the selected fuzzy set type. Therefore, the task of investigating the capabilities of type-2 membership functions in fuzzy logic systems is one of great interest.
Objective. Expanding the capabilities of fuzzy logic systems by using type-2 membership functions.
Methods. Research methods are directed towards utilizing interval and three-dimensional type-2 fuzzy sets in forecasting problems and medical diagnostics. The matter of investigating the capabilities of interval membership functions built on experimental data will be considered in two aspects: the first one – of how well interval membership functions reflect the uncertainties present in the source data, and the second one – of the advantages and disadvantages of an interval output of a fuzzy model with interval membership functions.
Results. A research of interval type-2 membership functions in fuzzy logic systems was conducted in the areas of forecasting problem and medical diagnostics. Applicability of three-dimensional type-2 membership functions built from experimental data was shown.
Conclusions. This paper shows the advantages of using interval membership functions in fuzzy logic systems, when developing fuzzy models using the multiple models principle. A research of three-dimensional type-2 membership functions’ applicability when modeling existing uncertainties is given. A technique for generating three-dimensional membership functions in fuzzy logic systems generated from experimental data is proposed.
Keywords: experimental data; type-2 membership functions; interval fuzzy model; three-dimensional membership function.
MULTIPLE STATE PROBLEM REDUCTION AND DECISION MAKING CRITERIA HYBRIDIZATION /V.V. Romanuke - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. Due to that decision making is always involving a great deal of approaches and heuristics, and poor statistics and time course can generate series of decision making problems, the problem of regarding multiple states and criteria is considered.
Objective. The goal is to develop an approach for reducing the multiple state decision making problem along with regarding multiple criteria by their hybridization to solve disambiguously a single decision making problem.
Methods. An algorithm of reducing a finite series of decision making problems to a single problem is suggested. Also a statement is formulated to hybridize decision making criteria allowing to get a single optimal alternatives’ set.
Results. Practically, this set contains just a single alternative. And, owing to the law of large numbers (of multiple criteria), the greater number of criteria is involved into the hybridization, the more reliable decision by the formulated statement is.
Conclusions. The represented multiple state problem reduction and decision making criteria hybridization both provide a researcher with the one decision making problem whose number of optimal solutions must be less than that by any other approaches. Besides, it allows to rank alternatives at higher reliability and validity. Furthermore, reliable weights (priorities) for scalarizing multicriteria problems are produced.
Keywords: decision making problem; multiple state problem; reduction; hybridization of criteria.
FINANCIAL RISK FORECASTING USING NAЇVE AND TREE AUGMENTED CLASSIFIER BASED ON BAYESIAN NETWORKS /O.N. Terentiev, V.E. Kyrychenko, N.O.Sviazinska,T.I.Prosyankina-Zharova - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. Development and study of characteristics for naïve and tree-augmented classifiers in the form of Bayesian networks in the problem of credit risk estimation.
Objective. To perform estimation of classification quality for the bank credit borrowers using Bayesian classifiers of two types.
Methods. Development of necessary mathematical tools and performing computational experiments aiming towards constructing classifiers in the form of Bayesian networks using actual statistical data characterizing solvency of bank credit borrowers.
Results. The following results were achieved: the methodology of constructing and application of the naïve and tree-augmented Bayesian classifiers for solving the problem of solvency estimation for bank credit borrowers; an analysis of computational algorithmic complexity was performed; two classification models were constructed in the form of Bayesian networks using actual statistical data from banking system; a comparative analysis was performed for the models developed.
Conclusions. It was established that the tree-augmented classifier exhibits higher computational complexity than the naïve Bayesian one, but it showed higher classification results while solving the problem of bank clients classification into two groups: those who return the credits and those who don’t.
Keywords: intellectual data analysis; Bayesian networks; credit scoring; financial analysis; macroeconomic indicators.
STRUCTURE AND PROPERTIES OF DIRECTIONALLY SOLIDIFIED MO-8.7 SI-18 B ALLOYS /Y.I. Bogomol, O.I. Poppvych, M. Krueger, P.I. Loboda - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. The research of alloys of the Mo–Si–B-system, which are a new type of heat-resistant alloys for the manufacture of gas turbine blades to replace nickel single crystal superalloys.
Objective. The purpose is to study the effect of the kinetic parameters of crucibleless melting zone and redundancy of boron on the regularity of directionally solidified eutectic Mo-8.7 at. % Si-18 at. % B alloy’s formation of structure and mechanical properties.
Methods. Directionally solidified Mo-8.7 at. % Si-18 at. % B and Mo-8.7 at. % Si-18.5 at. % B alloys were produced by crucibleless melting zone of not sintered powder compacts. Microstructure analysis of the obtained reinforced composites and chips, X-ray analysis, the study of micromechanical properties with a dispersion analysis of the data were conducted.
Results. Directionally solidified Mo-8.7 % Si-18 % B, Mo-8.7 % Si-18.5 % B alloys and fast solidified Mo-8.7 % Si-18.5 % B alloy were produced, their microstructure consists of intermetallic matrix reinforced with inclusions of solid solution of molybdenum. Integrated micro hardness of the received alloys reaches 11.86 ± 1.49 GPa and fracture toughness – 6.92 ± 0.68 MPa×ml/2.
Conclusions. The increase of the rate of crystallization leads to a natural refinement of the structure and increase of the anisotropy in matrix phase. It is shown that the introduction of boron in amount of 0.5 at. % leads to a decrease of the equilibrium from Mo-Mo5SiB2-Mo3Si to Mo-Mo5SiB2-Mo2B. The microhardness is anisotropic and fracture toughness is mostly isotropic.
Keywords: high-temperature structural materials; crucible-free zone melting; directional solidification; Mo–Si–B-system; microstructure; phase composition; microhardness; fracture toughness.
THE INFLUENCE OF ABRASIVE INSTRUMENT AND CUTTING MODES IN FINE GRINDING OF WEAR RESISTANCE COMPOSITE PARTS ON THE PARAMETERS OF SURFACE ROUGHNESS FRICTION OF PRINTING MACHINES /А.P.Gavrish, Т.A Roik., Р.O Kyrychok., R.A.Khokhlova - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. Study on the technological process of thin abrasive grinding of wear resistance 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 processes of thin abrasive grinding of friction parts made of new composite materials based on nickel and identification of influence on the parameters of part surface roughness of the abrasive instrument type, its granularity and cutting modes.
Methods. Surface treatment of printing machines wear-resistant parts based on nickel by thin grinding on the plain-grinding, round-external-finishing and internal-grinding machines with grinding instruments made of chromium electrocorundum (33A) with granularity 14–28 µm on the glyphtal bond and application of thin cutting modes.
Results. It was show, that granularity, the abrasive instrument bond material and parameters of thin abrasive grinding essentially influence the parameters of surface roughness machining Ra. The best performance Ra parameters satisfy the grinding chromium electrocorundum 33A discs with granularity 14–28 µm on the glyphtal bond and thin cutting modes that meet the high requirements at work surfaces of friction parts for printing machines. Advantage of the surface machining with grinding chromium electrocorundum discs was shown.
Conclusions. Also it was demonstrated, that the formation of high quality parameters of details surface, made of new composite materials based on nickel essentially depends on the type of the abrasive instrument, cutting modes of composites and bond material. The recommendations on the production were developed.
Keywords: new composite materials; nickel alloy wastes; tool; friction parts; surface roughness; thin abrasive grinding; cutting modes.
APPLICATION OF THE DIGITAL ORTHOGONAL METHOD OF PHASE MEASUREMENT FOR CHARACTERISTICS MATERIALS DEFINITION BY ULTRASONIC METHOD /G.A. Bogdan, A.G. Protasov - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. The article is devoted to the problem of accuracy increasing for physical-mechanical characteristics definition of powdered materials at the stage of their manufacture using ultrasonic testing.
Objective. The realization of the phase method of time interval measurement in a system of ultrasonic testing of powdered materials in order to increase accuracy of definition their physical-mechanical characteristics is done.
Methods. It was proposed to use digital orthogonal method for definition of the phase shift between signals to reach the aim. Computing simulation in Matlab system for definition of the signals phase shift and estimation of its inaccuracy of measurements was carried out.
Results. As the result of this investigation it was defined the optimal parameters of the principal element of a measuring system for the phase shift – ADC which was the main source of errors and essentially influenced the measurement accuracy.
Conclusions. Experimental investigations on well known materials indicated effectiveness of application of the digital orthogonal method which allowed defining the velocity of ultrasound propagation in a solid medium with accuracy less than 1 %.
Keywords: phase shift; digital orthogonal method.
ACTIVE PIPELINE'S DEFECTIVE AREAS MAINTENANCE TECHNIQUE BY MEANS OF WELL-BOND JOINTS /G.S. Tymchik, A.A. Podolian - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. Pipeline strengthening technique by applying well-bond joints filled with molten metal or an alloy has been examined. The main disadvantage of the above mentioned technique is that it is difficult to ensure under-joint area sealing.
Objective. To develop the strength increasing technique of the high pressure pipelines parts using the well-bond joints filled with molten metal enabling to achieve high efficiency of medium and small diameters tubes strengthening.
Methods. Strength increasing technique of a working pipeline with the help of well-bond joints.
Results. Improved active pipeline's defective areas maintenance technique has been offered. We have also offered face seal design that makes it easier to form under-joint layer that has optimal parameters.
Conclusions. The offered technique improves the efficiency of strengthening the average and small pipes diameter.
Keywords: joint; nondestructive testing; test operation; maintenance; gas pipeline; pipeline system; pressure.
MEASUREMENT ERROR OF AMETROPIA AND SCOPE OF EYE PSEUDOACCOMODATION BY IMAGES OF LIGHT MICROSPOT ON THE RETINA /I.G. Chyzh, O.O. Holembovskyi - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. The development of new methods and tools for an objective assessment of the volume optical component of pseudofackic eye pseudoaccommodation are done as well as the ways to improve the accuracy of these measurements.
Objective. The reasoning of the measuring possibility of the ametropia value and pseudoaccommodation volume through the reflection of the dependence on the mean square value defocusing (RMS) of the light microspot image radius on the retina was done.
Methods. The mathematical representation of RMS function, which is argumented by value of artificially formed defocused microspot image on the retina. Computer modeling using Mathcad functions RMS distortion of the electric noise.
Results. The quantitative dependence of errors of ametropia definition and scope of pseudoaccommodation on RMS function distortion level is revealed. The possibility of providing the required measurement accuracy in the proposed method is brought.
Conclusion. Existing electronic components allows you to implement a method of the ametropia measuring and pseudoaccommodation volume via RMS playback functions of light microspot on the retina. For the method it is quite achievable to measure these parameters with the error ±0.1 diopter.
Keywords: RMS of retinal image of the spot; amount of pseudoaccommodation of pseudofackic eye.
SYNTHESIS OF LUMINESCENT MATERIALS ON THE BASE OF RARE-EARTH ELEMENTS OKSOFLUORIDES /S.V. Pylypko, L.M. Spasonova, M.M. Plemjannikov - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. Development of new materials for the systems of reflection and registration of visual signals that can work in the infrared range remains an ongoing. Industry of optics ran into a problem, when the known systems based on silicate glass do not provide the necessary width of zone of transparency, and materials based on fluoride of metals have subzero chemical firmness.
Objective. The aim of the work is development of the methodology towards the synthesis and research of properties of fluoride glasses and oxyfluorides of rare-earth elements (REE) and yttrium.
Methods. To achieve the goal approach is applied in relation to a synthesis and research with the use of thermal, x-rayed, luminescent and other methods. As initial substances commercial connections ZrF4; LaF3; AlF3; GaF3; BaF2; YF3; Y2O3; EuF3; Eu2O3; GdF3; Gd2O3; TbF3; Tb2O3 were used.
Results. The possibility to create luminescent materials based on fluoride glasses of 95 % ZLAG + 5 % ZBLA and oxyfluorides of REE has been studied. For synthesis of these materials europium and terbium compounds have been used as luminophores emitting in visible spectrum.
Conclusions. According to the experimental data, it can be concluded that synthesized fluoride glasses can be used as perspective materials for optic amplifiers and lasers, where besides physical properties, one of the most important requirements is a possibility to take a necessary form of final product. The oxyfluorides having good photoluminescent yield and resistivity to aggressive milieu can be perspective materials for luminescent dispositifs of common use.
Keywords: luminescent materials; fluoride glass; oxyfluorides; rare-earth elements.
METHOD OF CONTROLLING THE MORPHOLOGY OF CATHODE DEPOSIT BY DETERMINING ELECTROCHEMICAL RESISTANCE FOR COPPER ELECTRODEPOSITION PROCESS /D.Yu. Uschapovskyy, O.V. Linyucheva, M.I Donchenko., M.V. Byk, A.S. Tsymbaliuk - K. Naukovi visti NTUU “КPІ”. – 2016. – N 2
Background. The intensification of compact copper electrowinning process based on increasing of maximal permissible working current density is an actual problem.
Objective. The aim of this work is the development of method for determining maximal permissible working current density of compact copper deposits based on application of electrochemical resistance (ri) versus working current density (і) dependences.
Methods. The method of cathodic polarization curves of copper deposition process with sulfate solutions was used. The morphology of cathodic copper deposits which had obtained under conditions of varying concentrations of copper ions, sulfuric acid, current density, had been studied by metallographic microscope.
Results. It was shown that maximal working current density of compact copper deposit formation, with permissible quality for hydrometallurgy, complies with beginning of growing after minimum r i – i curve. It was found that increasing of copper concentration leads to enlargement of minimal ri range, but increasing of acid concentration conversely narrowed this range. The equation which allows dividing of migration and diffusion components of limiting current density for this system was analytically received.
Conclusions. The determination of maximal current density of compact deposits formation under conditions of varying sulfate solution composition in copper electrowinning process is carried out for the first time on the basis of differentiation polarization curves method.
Keywords: cathodic polarization; cathodic deposit morphology; maximum current density inhibition effect; migration mass transfer.