Comprehensive Analysis of the Effective Rate in Adaptive Packet Radio Networks / Voiter A.P. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 7–12.
The aim of the study is to evaluate the effectiveness of joint work of physical and link layer packet radio networks with adaptive control of length of data packets in a competitive access to the radio channel. To do this, an analytical model in the form of two equations, the first of which determines the probability of successful transmission at the physical and data link layer, as a function of the intensity of the errors in the channel and protocol redundancy package format. The second equation is the probability of conflict-free transmission is a function of the length of the data packets and traffic load for non-persistent Carrier Sense Multiple Access protocol. Comprehensive analysis of equations determined the optimal length of the package and the effective rate of transmission. Proved that the adaptive management of multiple access protocol should be based solely on the procedures for increasing the length of packets on the optimal values for the data link protocol. The proposed mathematical model can be used in adaptive protocols packet radio networks to calculate the optimal values of the length of data packets with the combined effect of physical and link layer network with concurrent access to the radio channel, and to calculate the effective data rate for each set of system parameters.
Fig. 6. Tabl. 2. Refs.: 6 titles.
Calculating of the Heat Physic Characteristics of the Exhaust System of the Diesel Combined Internal Combustion Engine / Mazin V.O. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 13–19.
The purpose of research is to determine the coefficients of dynamic and kinematics viscosity, thermal conductivity of the exhaust gas of diesel CICE for typical states of exhaust systems. The research application methods are based on theories of gas mixtures using the Sutherland reduction formulas, combustion of liquid hydrocarbon fuels at the rate of stoichiometric proportions. Research results are quantities of viscosity and thermal conductivity coefficients of the exhaust gas by stoichiometric composition mixture with typical conditions for exhaust system of diesel CICE, dependencies of viscosity and thermal conductivity of exhaust gas from the combustible mixture composition by atmospheric pressure and temperature. The established performance error does not exceed 0,5 %. Our conclusions conform with classical ideas on studied properties of gases: viscosity and thermal conductivity of combustion products of the diesel CICE increase with rise of temperature and air content, as well as with the intense viscosity changes compared to thermal conductivity with the air content.
Fig. 2. Tabl. 6. Refs.: 22 titles.
Hardware Implementation Computations in Finite Fields Characteristics of Two / Dychka I.A., Onai M.V., Buhtiyarov Yu.V. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 20–27.
The article substantiates the need for hardware implementation of computational procedures in finite fields of the form GF(2m) with a high rate of speed. Analysis of different forms of the field elements GF(2m) representation was performed and showed that there is a need (in the process of computation) to move from one form of presentation elements to another, namely provide isomorphism field in hardware implementation. It was specified that for Galois fields with never-exceed 220 capacities it is expedient to use tabular method of elements field storage. Group of operations which should be performed on a numerical representation, and group operations, which should be performed on exponential representation elements field were selected. Architecture of computational tools for the implementation of operations in the field GF(2m), which during the computation combines exponential and numeric representation of the field elements, was proposed and it allows carrying out basic operations set of operands in a finite field. Simulation results of performance computations in finite fields of two properties in two ways of realization operations – software and hardware were shown.
Fig. 4. Tabl. 2. Refs.: 9 titles.
The Image Restoration Algorithms by Conventional Deconvolution Method in the Hadamard Transformation Field / Ivanyuk N.O, Rybin A.I. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 28–36.
The modification of conventional deconvolution method using discrete orthogonal Hadamard transformation is presented in this work. The computation of image degradation inverse matrix using symbolic method for this matrix forming of any order in the Hadamard transformation field is the main goal of the proposed algorithm realization. The algorithm takes into account block-diagonal structure of degradation matrix that allows considerably simplifying the matrix computation of any order. Usage of symbolic methods allows reducing the operation time to realize proposed algorithm, whereby numerical operations of addition and subtraction of identical units are excluded. It allows reducing the operation error. The proposed modification of restoration method in the Hadamard transformation field is easily programmed on the PC.
Fig. 7. Refs.: 16 titles.
The Monitoring System of the State Budget of Ukraine / Didenko O.O., Коval О.V., Senchenko V.R. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 37–48.
This article is devoted to the problem of building a system for monitoring the state budget of Ukraine, this system applies to instruments of state regulation of social and economic processes. As the design basis of the proposed model of the subject area consisting of an information model and precedent, which covers all the basic nature of the budget process and their relationship with the peculiarities of the budget system in Ukraine. The proposed model makes it possible to present the analytical work of an expert as a set of typical scenarios designed to monitor the budget process at all stages (preparation, approval, implementation and auditing of the budget). Based on the proposed model has been developed architecture and software system for monitoring the state budget of Ukraine.
Fig. 4. Tabl. 1. Refs.: 20 titles.
UDC 303.732, 517.9
Formalization of the Problem or Risk Management in Systems of Different Natures / Korshevnyuk L.А., Bidyuk P.I. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 49–54.
The paper considers the problem of formal statement of the general problem of integrated risk management in complex systems as a whole of different nature. Relevance of such formulations caused with the fact that the existing approaches are directed to local non-systemic risk analysis that do not focus on different and often multidisciplinary nature of the risks, and are not able to overcome the problem of cascaded development of risks. The statement of the problem based on the Merton model is considered. This model shows generalized, universal and idealized approach, where the risk is not presented in an explicit form, and therefore a detailed risk analysis is not valid in this case. The proposed approach to the problem formalization and solving is based on a detailed study of risk factors and situations. The optimal control strategy is based on the functional that provides a minimum negative effect of the risks in the system as a whole, minimizing the costs of risk management and provides prevention of the system ruin.
Refs.: 7 titles.
Force Field at Fine Diamond Grinding of Friction Pieces From New Composite Alloys for Printing Machines / Gavrish А.P., Кyrychok P.O., Roik Т.A., Vitsuk Yu.Yu. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 55–59.
The research results concerning an influence of cutting forces rectangular components at fine diamond grinding of friction pieces from new composite materials on the base of grinding alloy tool steel wastes type of 86Х6НФТ, 4ХНМНФС and 5Х3В3МФС for heavy operating conditions of printing machines have been presented in this article. The regularities of fine grinding parameters influence, type of diamond grain, granulosity and material of bond for quality parameters of working surfaces taking into account a formation mechanism of cutting forces components on cutting diamond grain top in grinding zone have been determined. It was defined the dependence of surface roughness for new high-alloy composite alloys for cutting conditions of diamond grinding process (rotation speed, line speed, rotation speed of diamond disc, cutting depth and granulosity of diamond disc). The recommendations were formulated to choose diamond discs and cutting parameters for industrial purposes in accordance with the requirements of the quality of high-speed bearings’ friction surfaces for printing machines.
Fig. 5. Refs.: 15 titles.
The Structure of Circulating Flows of Viscous in Compressible Fluid near the Radial Inner Baffles / Kovalev V.A. // Naukovi visti NTUU “КPІ”. – 2013. – N 5. – P. 60–64.
The results of numerical modeling of axisymmetric flows in tanks with rigid walls, the analysis of the structure and nature of the circulation of the time flow depending on geometrical parameters of partitions and like Reynolds numbers, Euler and Rossby. We found that the circulation flow near the walls can adjust the structure and energy characteristics of the main flow and significantly change the characteristics of the development trends in the area of influence partitions and near its inner edge. In addition, we obtain the data on rational baffles arrangement in the flow in the context of minimizing their weight and number, which is of great importance for the aircraft. The results of numerical and experimental data comparison show the qualitative agreement of results. We establish such characteristics of the flow field as the azimuthal velocity structure of the meridional circulation currents in each case of the flow. We give practical recommendations for design of these internal structures of stabilizing devices.
Fig. 4. Refs.: 4 titles.
Effect of Mechanical Vibrations on Microstructure of Single and Ceramic Composites during Growing from Melt / Loboda P.I, Bogomol Yu.I., Solovyova T.O. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 65–72.
The effect of mechanical vibration with 50 Hz frequency on the formation of microstructure and chemical composition of single crystals of lanthanum hexaboride and reinforced ceramic composites of LaB6–ZrB2 during crystallization from the melt and subsequent heat treatment was investigated. It was found that the mechanical vibrations affect the crystallization and lead to the equalization of the concentration profile of the distribution of atoms in front of the crystal growth, alter the shape and size of the melt zone and increase structural heterogeneity. Methods of optical microscopy, X-ray texture diffractometry, microanalysis and X-ray analysis show that as a result of mechanical vibrations changing the number, size and shape of the transition metal diboride fibers during directional solidification of eutectic alloy LaB6–ZrB2 occurs. Disorientation matrix and reinforcing phases relative to crystallographic growth direction, given by the seed crystal, which leads to poor monocrystallinity sample, appear. Increasing of the defect structure reduces the lattice period and density of lanthanum hexaboride and ceramic composite system LaB6–ZrB2.
Fig. 8. Tabl. 2. Refs.: 11 titles.
Methods of Creating a Layered System from Ore-Flux-Fuel Compositions with a Higher Content of Solid Fuel / Chernega D.F., Neschadim V.N., Kud P.D., Ivanchenko D.V. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 73–77.
Four methods of obtaining pellets with fluxing ore compositions with higher content of solid fuel, based on the combination of feedstock sintering process and sintering at a temperature of 1593–1598 K, namely: 1) a method wherein the solid fuel was mixed with the initial charge materials directly before agglomeration; 2) a method wherein the solid fuel was rolled on the surface of granules of size 10–15 mm, and after that pellets were burned out; 3) the method in which varying particles solid fuel (50 %) were also mixed with the raw materials before sintering, while the second part of them – was rolled on the surface of the granules, followed by imitation of the pellets real process of mixing with solid fuel in a drum mixer; 4) the method in which a solid fuel in an amount of 40 % was mixed with raw materials before sintering were experimentally investigated. Compression strength of burned out fluxing pellets with the higher content of powdered solid fuel, is changed within 1,9–2,45 kN/pellet and is not characterized as high index though it exceeds the requirements of GOST on 0,5–0,95 kN/pellet. The content of iron monoxide (FeO) and iron metal (Femet) in fluxed pellets after burning out was found and it was established, that FeO varies in range of 21,5–27,2 %, whereas Femet varies in range of 11,2–18,9 %. The maximum increase of these indexes was observed in the burned out pellets made according to the fourth method. Increasing the content of iron monoxide and, particularly, iron in the compact metallic charge materials indicates that the use of such technology is accompanied by the increasing of the hematite dissociation degree and plating in the final product and improving its metallurgical properties.
Fig. 3. Refs.: 7 titles.
Infrared Hybrid Lenses with Corrected Spherical Aberration / Kolobrodov V.G., Mykytenko V.I., Siryi Ie.A. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 78–81.
This paper proposes the method of monochromatic lens spherical aberration correction by designing it as a hybrid lens. This method is based on the equation, which allows obtaining designing wavelength and focal distant of the hybrid lens diffractive part. The spherical aberration of the obtained diffractive part is equal to the refractive part of spherical aberration but has an opposite sign within a given clear aperture. Using this method, we calculate the plano-convex germanium hybrid lens with low f-number, which forms perfect spherical wavefront for the operating wavelength. To increase the diffractive efficiency of the calculated lens to the required value, we propose to change the obtained designing parameters of the diffractive part. We show that the increase of diffractive efficiency of the hybrid lens enables the rise of spherical aberration, but the spherical aberration value of the hybrid lens is always less than that of the refractive one.
Іл. 3. Refs.: 5 titles.
Influence of Electroosmotic Phenomena on Transient Duration in Amperometric Gas Sensors / Buket O.I., Linyucheva O.V., Bludenko A.V., Nagorniy O.V., Linyuchev O.G. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 83–88.
The work is dedicated to the 100th anniversary of the birth of great scientist-electrochemist, corresponding member of USSR SA L.I. Antropov and continues series of studies of transients processes in amperometric sensors. Reasons of differences in the duration of transient processes in the measurements, differentiated break from several minutes to several hours, allowing time for the values of the output current signal by 10 and 50 % of its stationary value to estimate the expected value of reliable sensor signal prior to its stabilization were revealed. It was shown that the course of the electrode reaction causes a temporary increase in current-generating surface of the working electrode sensor, which leveled in a few minutes after stop the flow of detectable component in the sample gas mixture. The reason for this phenomenon is the osmotic accumulation of water in the current-generating reaction area due to absorption of vapor from the air and from the depth of diffusion of the electrolyte solution, which thickens the solution film and distorts the shape of the meniscus. During the existence of the meniscus, which shape is distorted by the previous generation current signal, transition time is reduced due to faster charging of working electrode polarization capacitance by greater than the current signal.
Fig. 6. Refs.: 6 titles.
The Development of the Electrochemical Methods for the Corrosion Rate Determination of Scientific School of L.I. Antropov / Gerasimenko Yu.S., Bilousova N.A., Vasyliev G.S., Vasylieva S.M., Klymenko A.V., Vyshnevska Yu.P. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 89–102.
The development of scientific bases of electrochemical methods for the determination of the corrosion rate, which were originated under the guidance of outstanding electrochemists L.I. Antropov and continued by his followers’ school, was investigated. Accuracy aspects of the corrosion rate determination by polarization resistance (R p) method were discussed. It was shown that application of the two-electrode cell significantly decreases R p determination error. The relations for the proportionality constant between R p and corrosion rate accounting the electrochemical double layer structure and the influence of specific ion adsorption were improved and experimentally tested. Analytical dependence for corrosion rate determination in the presence of large polarization capacities was derived. A method of non-linear double polarization for the kinetic parameters of corrosion determination was discussed using analytical equation in systems with diffusion or passivation control without application of empirical coefficients. New non-destructive methods based on polarization resistance with application of non-polarizable electrodes were described. The examples of the practical application of this method in corrosion research of welded connection were shown. Quantitative relations for films growth on the metal surface at different exposure time and acid concentration were derived from time dependences of polarization resistance in sulfuric acid in the presence of aminoacids and guanidine derivatives.
Fig. 9. Tabl. 8. Refs.: 34 titles.
Copper Production from a Carbonate Ores by Electrowinning Method / Donchenko M.I., Linyucheva O.V., Uschapovsky D.Yu., Redko R.M., Byk M.V. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 103–110.
A process of compact copper electrowinning from the solution obtained by leaching copper from the ore by sulfuric acid was discussed. It was shown that the ore leaching is advisable to carry out with 10 % hydrochloric acid for 30–40 minutes with intensive stirring of the mixture. Copper electrowinning process was done from a concentrated solution with a stepped reduction of the current density which was proportional to the copper ion concentration decreasing during the process. The comparison of the parameters of the real and theoretical calculated processes was performed. It was found that the prediction of optimal electrolysis conditions can be achieved by electrochemical characteristics, initial metal concentration and geometric parameters of the electrochemical cell. An experimental cell voltage dependence of the acid concentration, copper ions and the cathode current density was determined. It was found that the main component of the cell voltage is electrochemical component – the difference potential at the electric current. The decreasing of the cell voltage in time was shown and the relative cost of electricity in the producing of copper by electrowinning was calculated.
Fig. 5. Tabl. 2. Refs.: 8 titles.
UDC 621.35; 65.012
Causal Diagrams Constructing for Sealed Electrochemical Devices on the Method of Ascent from the Abstract to the Concrete / Ihnatovych V.M. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P. 111–115.
The sequence of actions to build generalized causal diagrams for sealed electrochemical devices, which can be sealed primary and secondary chemical sources of electric power, ultracapacitors, electrochemical sensors and others device based on the specified settings, was described. Diagram allows visualizing the relationship of various factors affecting electrochemical devices and their stability during storage and use. Unlike commonly known causal Ishikawa diagram, chart described in the article was built not for one parameter of a product but built for the product as a whole, the quality of which is characterized by several parameters. In addition, it includes possible causes of modified electrochemical devices during storage and operation. Causal diagram for the product can be used to develop design and technology of electrochemical devices, and to manage their quality during production. Method of diagram constructing in material terms coincides with the philosophy known as method of constructing a theory of complex object of study – the method of ascent from the abstract to the concrete.
Fig. 1. Refs.: 6 titles.
UDC 620.193.197 (075.8,076)
Modelling of Organic Compounds Adsorption on Metals Based on the HSAB Concept / Pogrebova I.S. // Naukovi visti NTUU “КPІ”. – 2013. – N 6. – P.116–126.
The adsorption process of surfactants on metals from the perspective of the charge-transfer complexes formation and their stabilization by charging and electronic (orbit) interaction is discussed. The expediency of Lewis-Usanovych acid-base balance and coming out of it principle of Pearson’s “hard” and “soft” acids and bases (HSAB) application in modelling of adsorption processes is shown. Equations that corresponds to the electrode adsorption equilibrium, conditioned by charging, electronic and charge-electron interaction are derived and qualitatively validated. It is found that the most important characteristics that are responsible for the adsorption of organic compounds on metals are the charge number, ionization potential of organic compounds, j-potential of the electrode and the electron work function of the metal. In terms of the proposed model metals are distributed between two extreme adsorption groups: differing by selectivity of adsorption and electrochemical properties. The prospects of proposed model application in prediction of the mechanisms of various electrochemical processes, which are based on adsorption phenomena, are shown.
Fig. 2. Tabl. 1. Refs.: 30 titles.