Retransmission Method of Impulse Ultrawideband Signals in Ad-Hoc Networks /Bunin S.G., Plotnyk K.O., Voitenko Iu.Iu. // Naukovi visti. - 2012. – N 5. – P. 7–11. Fig. 1. Tabl. 7. Refs.: 7 titles.
This paper describes a new method of data relay in wireless Ad-Hoc networks with impulse ultrawideband radio signals (IR-UWB). Proposed method uses concept of “chipset retransmission” rather than typical store-and-forward scheme. This implies a relay by the intermediate nodes of each particular bit of data, encoded as chipsets, and the use of special markers integrated into that bit transferred in the connection. This provides lower delays and, thus, gives unprecedented advantage in fast retransmission for the multihop environment. Some problems still exist for further examination, such as inability to distinguish bits in a stream, error correction on bit level, ensuring uniqueness for each marker and bit code. Therefore before employing this method nodes should exchange some preliminary parameters in order to exploit all the advantages of this method. These parameters are shown in this paper as well as an example of their integration into well known reactive protocols, such as AODV, are studied.
Simulation of Current-Voltage Characteristics of Triode Technological High Voltage Glow Discharge Electron Sources with Taking into Account Processes of Interaction of Charged Particles in Anode Plasma/Denbnovetskiy S.V., Melnyk I.V., Melnyk V.G., Tugay S.B. // Naukovi visti. - 2012. – N 5. – P. 12–18. Fig. 3. Refs.: 16 titles.
The paper studies the problems of mathematical simulation of triode high voltage discharge gap and defines its current-voltage characteristics. We obtain analytical relations to calculate current-voltage characteristics of triode high voltage glow discharge (HVGD) electron sources. The proposed calculation technique is based on analyzing charged particles balance in HVGD anode plasma taking into account the condition of self-dependence of its lighting. The model is very simple and universal. Basic model parameters are geometry dimensions of discharge gap, specifically the longitudinal length of anode plasma, which can be calculated analytically by solving the cubic equation. It is classified as physical-topology model and allows making preliminary theoretical estimations of energy parameters of HVGD electron sources at the pilot design stage. Divergence between calculations and experimental data is less than 15 %.
Nanocrystalline Silicon thin Film Solar Cells/ Koval V.M., Bogdan A.V., Ivaschuk A.V., Yakimenko Yu.I.// Naukovi visti. - 2012. – N 5. – P. 19–26.
Tabl. 1. Refs.: 30 titles.
The aim of this paper is to determine advantages and disadvantages of replacing amorphous silicon by nanocrystalline one in thin film solar cells with different structures. Review of national and international literature has shown the effective technologic ways of replacing amorphous silicon by nanocrystalline one in each of three possible structures of photovoltaic cells: structure of a p-n-junction, cascade or multi-layered structure and НIT structure. In this paper the design and technologic features of thin film photovoltaic cells based on nanocrystalline silicon are presented taking into account the type of technologic layer replacing this material (wide-band window layer, i-layer, base, buffer or tunnel layer). We discover that the new design of solar cells – HIT structure – is optimal in terms of efficiency of solar energy conversion, cost and technologic simplicity of the device showing the prospects of this novel structure of photovoltaic cells for mass production.
Research of Characteristics of L-Shaped and Waveguide with Two Corner Cuts by Variational Method /Naidenko V.I., Postulga O.S. // Naukovi visti. - 2012. – N 5. – P. 27–33. Fig. 7. Refs.: 10 titles.
Waveguides with one and two cuts (L-shaped waveguide and waveguide with two corner cuts) are used in microwave devices. Therefore, there is a need for new effective and rapid methods for calculating the characteristics of such waveguides. The variational method is used to calculate the eigenvalues of waves of L-shaped waveguide and waveguide with two corner cuts with arbitrary geometrical parameters. Polynomials orthogonal over the area of considered waveguides are unknown. We consider several types of the field approximation: on the basis of trigonometric and power functions. Field approximation by trigonometric functions gives more accurate results in calculating eigenvalues and requires less mathematical operations. Increase of the system order leads to an increase of the condition number and instability of the solution. Variational method gives eigenvalues of the waves with great accuracy for large cuts and a small number of transactions. Results can be used in design and synthesis of microwave devices based on the L-shaped waveguide and waveguide with two corner cuts.
The Tensor Model of Ports Buffering for Digital Switch /Tikhonov V.І. // Naukovi visti. - 2012. – N 5. – P. 34–39. Fig. 5. Refs.: 15 titles.
The objective of the paper is to develop the tensor model of buffer storage allocation for the input-output ports of digital network switch. To this end the method of segregated lists applied where each external physical port of the switch comprises internal transit buffers for all other external ports. Through experiments performed, we introduce the notion of zero port for the switch that connects external ports with the switch itself as the object of addressing object. The buffering matrix and the quaternion of an arbitrary couple of buffers is provided for the switch ports. The reduced port buffering matrix is obtained for the even size case of the one-direction interacting input and output buffers. The reduced matrix decomposes in symmetric and anti-symmetric buffering matrix parties. The symmetric buffering matrix is mapped onto the real metric buffering tensor. The anti-symmetric buffering matrix is mapped on two tensors: the real curvature tensor of buffering and complex rotor tensor of buffering. We conclude that it is feasible to use dynamic storage allocation in network switches based on the buffering tensor model.
Experimental Study of Characteristics of Moving Water Film within Netting / Kuzmenko I.M., Kryachok А.S.// Naukovi visti. - 2012. – N 5. – P. 40–44. Fig. 6. Tabl. 1. Refs.: 10 titles.
The effects of netting characteristics, sprinkler construction and irrigation density on the moving water film in the net surface is experimentally studied. Netting surface irrigated by water was supplied through some type of sprinkler without the air flow. The film thickness in the netting is determined empirically using the amount of delayed water. The delayed water was collected by clipping. The percent error of the experiment is up to 6 %. Increasing the irrigation density correspond qualitatively to the thickness of water film according to Nusselt’s formula. Using netting with minimal geometric dimensions leads to formation of ultra thin films. The film thickness of spray irrigation is reduced compared with the overflow irrigation. Recommended design of spray nozzle with holes whose diameter corresponds to manufacturability and there is one hole (nozzle) per 50 mm physically irrigated surface. Film movement is a movement in the netting structure and corresponds to fluid flow around cylinder.
Mikhailenko V.S., Kharchenko R.Yu.
Synthesis of Neural Network System of Automatic Control of Water Level in the Boiler Drum Power Block of Thermal Power Plant / // Naukovi visti. - 2012. – N 5. – P. 45–50. Fig. 7. Refs.: 13 titles.
The purpose of this paper is synthesis of intellectual automatic control system (ACS) of the water level of drum boiler unit based on the theory of neural networks. We develop a mathematical model of the research object. Analysis of the transients quality under different operating boiler shows that the traditional ACS has significant drawbacks associated with significant regulation time and the first rejection. To improve the traditional ACS and its efficiency, we propose to use a neural network approach to control. We synthesize a neural network controller (NNC) trained to determine the optimal control actions to compensate for the deep disturbances caused by peaks and adjusting modes of power. To test the proposed solutions in the program MatLab (Simulink, NT) computer experiments are conducted to develop and to test a neural network control system. Analysis of the transients quality when conducting an experiment to determine the robustness and stability of the NNC in the deep impact of external and internal disturbances, advantages of adaptive neural network system compared to the traditional combined one, requires a period of adaptation.
The Research of Instability of the Amplitude Frequency Characteristic of a High-Voltage Potential Divider Caused by Non-Identical Elements of its High-Voltage Shoulder / Atarod Soroosh, Brzhezytskyy V.A. // Naukovi visti. - 2012. – N 5. – P. 51–54. Fig. 3. Tabl. 2. Refs.: 5 titles.
Based on repeated measurements, we define real distribution of capacity values of condensers of a high-voltage shoulder of a potential divider with the assumed deviation from the nominal equal to ± 5%. We show that the given distribution is asymmetric in relation to rating value (22nF). Renormalization of received distribution was done in relation to the average capacity value of condensers. We investigate the influence of real distribution of condensers capacities on instability of the amplitude frequency characteristic (AFC) of a high-voltage potential divider. We demonstrate that the influence of the real distribution of condensers capacities with the deviation ± 5% on AFC instability of a divider is less expressed in relation to the law of normal distribution with an average quadratic deviation equal to ± 5%. We prove that the deviation of condensers capacity of a high-voltage shoulder ± 5% is acceptable. The set deviation of capacities ± 10% usually leads to unacceptably high instability of AFC of a high-voltage potential divider.
Modification and Application of Stochastic Volatility Model/ Bidyuk P.I., Konovaliuk M.M. // Naukovi visti. - 2012. – N 5. – P. 55–60. Fig. 1. Tabl. 3. Refs.: 7 titles.
A modified structure of autoregressive stochastic volatility model is proposed and empirically studied that includes delayed historical volatility values. The structure of the model developed is refined with the use of the partial autocorrelation function computed for sample values of the conditional variance process. The volatility logarithms correspond to the stationary autoregression process that provides a possibility for forecasting of the conditional variance dynamics with known model parameters. To compute the model parameters using actual data the Markov chain Monte Carlo procedure was selected and appropriately modified to generate pseudorandom sequences for parameter estimates with necessary distribution. It was established that the model proposed provides better quality of volatility forecasts than known stochastic volatility model. The necessary computing experiments have been carried out with the developed software that is also accessible to other users via Internet. The modeling system developed can be easily expanded with new functions, methods for model parameters estimation and forecasting, and modified appropriately to meet requirements of a specific user.
Hardware Implementation of Multiplication and Division Operations for Polynomials in Finite Fields / Dychka I.A., Golub V.I., Onai M.V.// Naukovi visti. - 2012. – N 5. – P. 61–66. Fig. 5. Refs.: 12 titles.
In this paper we prove it is necessary to implement hardware or hardware-software operations in Galois fields. Specifically, we demonstrate that hardware implementation is preferable for multiplication and division operations on polynomials with coefficients that belong to the finite field. It is also feasible to run these operations on separate functional units. We develop formulas that allow skipping summation cycles if the bars being summed contain zero values. Algorithms for evaluating the coefficients as well as the function unit diagram for multiplying and dividing the polynomials in the field GF(N) are provided. We show that the hardware implementation of these operations in finite fields significantly increases computational efficiency.
Optimal Decision-Making on Stabilization of Euro/Dollar Rate on the Basis of Mathematical Models with Multirate Sampling /Romanenko V.D., Reutov О.А. // Naukovi visti. - 2012. – N 5. – P. 66–74. Fig. 6. Tabl. 1. Refs.: 10 titles.
The present paper describes development of the model structure of the euro/dollar with 2 lags members of input, 11 input factors with sampling 5 days or month and 2 controls with sampling 5 days. We choose the factors to take into account the theoretical material on the subject and to achieve the highest possible quality at such high rate sampling. 5 days sampling characterized by significant speculative fluctuations require frequent adjustment of the coefficient. At the second stage we synthesize the optimality criterion in the form of generalized variance. By minimizing the optimality criterion we define the equation for optimal decision-making on both controls. Disadvantages of this approach are that the model may change over time requiring its constant adjustments and possible lack of harmonization between the FED and ECB. Results of numerical simulations show possibility of reducing the synthesized indicator in the form of generalized variance. The model development allows evaluating the influence of different variables and considering possible impact of changes in control on the input given the historical relationship between variables.
Criterion of Eliminating Single-Parameter Model Uncertainty with Principle of Assuredly Minimal Absolute Lacks and Arithmetic Mean / Romanuke V.V.// Naukovi visti. - 2012. – N 5. – P. 75–80. Refs.: 13 titles.
There is stated a problem of generation and removal of model uncertainty regarding a single parameter of the being investigated object, which is described with more than one mathematical model. Using the arithmetic mean in removing such single-parameter model uncertainty is compared to the principle of assuredly minimal absolute lacks on the base of the corresponding antagonistic game with symmetric matrix. It has been shown that for the second player optimal strategy, whose support contains equiprobable pure strategies of selecting minimal and maximal values of the being investigated parameter, the corresponding evaluation of the model is not worse than the same evaluation as the arithmetic mean over fixed model values. It is pointed that the nonstrict problem of single-parameter model uncertainty elimination may be solved with the arithmetic mean or principle of assuredly minimal absolute lacks, depending on where minimum of deviate of the being investigated parameter value estimation from its real value is going to be reached. For the strict problem of single-parameter model uncertainty elimination there is suggested to apply all the fixed model values with a probabilistic distribution, being the nearest to the equiprobable distribution within the set of the second player optimal strategies.
Temperature Dependence of Mechanical Properties of Eutectic (a-Al Mg2Si) Alloys /Volkova H.I., Danilenko V.I., Korzhova N.P., Legkaya T.N., Podrezov Yu.N. // Naukovi visti. - 2012. – N 5. – P. 81–85. Fig. 7. Tabl. 1. Refs.: 19 titles.
We investigate mechanical properties of complex alloys with eutectic (a-Al–Mg2Si) structure for high-temperature application. Specimens are annealed at the temperature of 300 °С during 5 hours to obtain uniformly distributed dispersed Al3(Sc1–xZrx) nanoparticles in a-Al phase. Investigation of mechanical properties of alloys with different content of eutectic component by a tension method is carried out in the interval of temperatures 20–400 °С with speed of 10-3 s-1. The content of eutectic compound is determined by metallographic method. The alloys microstructure with different eutectic content is studied and fractography analysis is conducted. We determine the fracture mechanism and main factors that have an influence on strength and plasticity at different temperatures. Experimental results enable to optimize alloys composition and obtain the best combination of strength and plasticity for different applications. Alloys under consideration have yield strength of ³ 100 MPa at the temperature of 400 °С. Alloys that contain more than 30 vol. % of eutectic compound necessary for good casting properties are competitive comparing to the best existing cast aluminum alloys.
Influence of Annealing Temperature on Structure and Magnetic Properties of Nanodimensional Fe50Pt50(15 нм)/ Ag(30 нм)/Fe50Pt50(15 нм)/SiO2(100 нм)/Si(001) Film Composition / Makogon Iu.M., Pavlova O.P., Verbitska T.I., Vladуmyrskyi I.A.// Naukovi visti. - 2012. – N 5. – P. 86–91. Fig. 6. Refs.: 11 titles.
We study the influence of annealing temperature in range of 300–900 °С and intermediate Ag layer on processes of diffusional phase formation and transition of chemically disordered magnetic-soft А1(FePt)FCC phase to chemically ordered magnetic-hard L10(FePt)FCT phase in nanodimensional Fe50Pt50(15 nm)/Ag(30 nm)/Fe50Pt50(15 nm) film composition (NFC) on SiO2(100 nm)/Si(001) substrate. We investigate its structure, morphology and magnetic properties. We show that after deposition in NFC under study the phase А1(FePt)FCC is observed. The formation of L10(FePt)FCT phase occurs at annealing 600 °С for 30 s that is lower by 100 °С than in NFC without intermediate Ag layer. We also assume that surface energy depending on stressed state of layer interfaces in nanodimensional layered composition influences on diffusional phase formation. Increase of annealing temperature to 900 °С is accompanied with sharp increase of amount of L10(FePt)FCT grains with (001) texture and surface roughness. Structural and phase transformations in NFC under study during heat treatment are accompanied with change of its magnetic properties. After annealing at 900 °С the ordered parameter S achieves the largest value of 1,55 which corresponds to maximum value of coercivity of Нс ~19 кОе.
The Current State of Production Capacities of Metallurgical Industry in Ukraine /Chernega D.F., Neschadim V.M., Kud P.D., Ivanchenko D.V. // Naukovi visti. - 2012. – N 5. – P. 92–96. Refs.: 17 titles.
The paper presents the analysis of the current state of the metallurgical industry in Ukraine and highlights key problems of its revival in the post-crisis period. Most of domestic steel enterprises use outdated technologies such as open-hearth production and blooming. In addition, the equipment depreciation in average is about 65 %. It hinders Ukrainian steel producers to successfully compete in domestic and foreign markets. A significant drawback of the current state of the industry is limited government backup and impact on its development. We show that upgrading and modernizing of steel plants is performed slowly and the government does not pay enough attention to introduction of high-tech energy-saving technology which makes domestic steel production more energy-consuming than the EU and other industrialized countries. Specifically, introduction of pulverized coal instead of natural gas in the blast furnace will reduce coke consumption in the blast furnace to 7 %, increase the productivity of the furnace by 8 % for every 10 % of metallic iron in the charge. Addressing the most important problems, namely modernizing and upgrading of existing steel plants, energy-saving technologies, state support for innovative models of industry development, promoting production of high-tech products, development of the domestic steel market must be made. All these measures can significantly improve the steel industry and improve competitiveness of domestic products on world markets.
Navigational System Exactitude for Automatic Landing of Unmanned Airplanes/ Zbrutsky O.V., Burnashev V.V.// Naukovi visti. - 2012. – N 5. – P. 97–101. Fig. 2. Refs.: 5 titles.
The paper aims at solving the issue of defining the navigation system exactitude to fulfill unmanned airplane automatic touchdown on landing gear. Trajectories of automatic touchdown are designed. The mode of the autoflare program shaping comprising rigid and free parts is proposed. It permits to reduce an air part of landing distance and to improve the stabilization quality. In view of a flare path shaping mode performances limitations of navigation and attitude system as inequalities containing measurement errors and errors of stabilization of motion parameters are obtained. Based on their performances, characteristics of navigational system for FAKS-1 unmanned airplane are calculated. Furthermore, we model the unmanned airplane automatic touchdown controlled by navigational system signals.
The Problems of Designing Coherent Spectrum Analyzers /Kolobrodov V.G., Tymchyk G.S., Nguyen Q.A. // Naukovi visti. - 2012. – N 5. – P. 102–108. Fig. 4. Refs.: 10 titles.
The purpose of this paper is to improve methods for designing coherent spectrum analyzers. Methods of calculating generalized characteristics such as the working range of spatial frequencies, the spatial spectral resolution and the energy resolution are suggested in this paper. To develop the methods of calculating we consider the most common scheme in which the transparency locates in the front focal plane of the Fourier lens. As transparency, we take a rectangular aperture that has spatial spectrum described by sync functions. We obtain main expressions and the algorithm for energy calculations for the input signal at the Nyquist frequency. Moreover, we give the example of calculation of generalized characteristics. Based on main expressions of calculating generalized characteristics of the coherent spectrum analyzer and the example, we discover that magnitudes of characteristics depend on parameters of the optical system and the matrix photodetector. Due to these methods, it is possible to choose optimal dimensions and parameters of the device components to improve properties of the latter.
Definition and Analysis of Metrological Characteristics of Oxygen Sensor /Kotovsky V.Iо., Ivchenko P.О., Roytman E.M., Dovzhenko О.P. // Naukovi visti. - 2012. – N 5. – P. 109–113. Fig. 1. Tabl. 2. Refs.: 8 titles.
The purpose of this paper is to develop optimum designs of oxygen sensor, technologies of sensors, and new methods of processing initial signals aimed at increasing metrological characteristics of oxygen sensor. We investigate the influence of external (atmospheric pressure, ambient temperature, availability of impurity) and internal factors of the system (design features of oxygen sensors, materials of electrodes and gaze-diffusion membranes, electrolyte structure) on sensors’ metrological characteristics. The increase of metrological devices’ characteristics to certain borders is reached by reducing the area of working electrode which leads to reduction of oxygen expenses on the analysis and respectively the influence of device on the object under study. Studying the influence of different factors on metrological characteristics of oxygen sensor, searching for optimum conditions of their application in definite situations will open new prospects for increasing technical characteristics of the oxygen gas analyzers. Furthermore, the determined optimum characteristics of sensors at this stage will be used to develop next generations of devices in future.
Achromatization and Athermalization of Infrared Technology Objectives /Kucherenko О.K., Muraviov О.V., Tyagur V.M. // Naukovi visti. - 2012. – N 5. – P. 114–117. Fig. 2. Tabl. 1. Refs.: 3 titles.
This paper considers the method of temperature influence indemnification to image quality of optical systems working in the infrared range of spectrum for the case of homogeneous temperature distribution through the system. The simultaneous achromatization of focusing knot is possible when passive athermalization is used. Rational problem decision of athermal and achromatic optical system designing is possible when the triplet including specific compositions of optical materials combined with specific mechanical housing materials is utilized. The algorithm proposed allows obtaining athermal and achromatic three-component optical system by selecting necessary combination of materials. In addition, we give some recommendations on how to select the triplet materials based on the dependence diagram of optical and thermophysical materials properties. The method includes the influence of housing material expansion of focusing knot when the ambient temperature changes. We also consider examples of possible combinations of optical and mechanical materials for the infra-red waveband of spectrum of 3–5 and 8–12 mm.
Resource Recycling Technologies Stems Miscanthus /Barbash V.A., Zinchenko V.O., Trembus I.V. // Naukovi visti. - 2012. – N 5. – P. 118–124. Fig. 2. Tabl. 4. Refs.: 17 titles.
Processes of obtaining pulp from Miscanthus stems for the production of paper and cardboard, microcrystalline cellulose and pellets were investigated. The chemical composition of Miscanthus giganteus stems was determinated. Established that the Miscanthus contains more cellulose, pentosans, minerals and less lignin than wood. The influence of main technological parameters on the quality indexes of organosolv pulp obtained from Miscanthus stems was investigated. The use of miscanthus organosolv pulp in composition of writing paper and paperboard container was experimentally confirmed. The influence of preliminary hydrolysis duration Miscanthus stems on ash content and polymerization degree of microcrystalline cellulose was presented. It was established that performing preliminary hydrolysis by water-alcohol solution and oxide-organosolv pulping by hydrogen peroxide solution and acetic acid allows obtaining microcrystalline cellulose from miscanthus stems. Obtained microcrystalline cellulose meets the requirements of standards by its quality indexes. Laboratory samples of pellets from the stems of miscanthus correspond to the indexes of European standards for wood pellets by density (1,26 g/cm3) and calorific value (18,9 kJ/kg).
The Investigation of Properties of Acrylic Hydrogels as Materials for Artificial Soils / Godynchuk N.V., Nikovska G.M., Kernosenko L.A., Samchenko Yu.M.// Naukovi visti. - 2012. – N 5. – P. 125–129. Fig. 3. Tabl. 1. Refs.: 9 titles.
This paper studied the adsorption of cations, anions, nanometric metal-organocomplexes from the individual and binary solutions by acrylic hydrogels. We establish that the efficiency of sorption and strength of retention of metal compounds as cations is higher than of anions. Thus the number of bioelements adsorbed by acrylic hydrogels decreases in the row: Fe3+ > Cu2+ > Mn2+ >MnO-4 > (Cu–Г)- > (Fe–Г)- >H2PO-4 , while their desorption obeys an inverse relationship. Adsorption of bioelements is synchronous with swelling of hydrogels, desorption (in acidic medium at pH 4) – with their collapse. By efficiency сriteria of bioelements sorption and slow desorption into the environment the hydrogel based on acrylamide-acrylonitrile has optimal parameters and can be used as an active component of the artificial soil or in mixture with a neutral filler (sand). Hydrogel matrix is brought into equilibrium with solutions of bioelements with final treatment by sulphate- and phosphate-containing solutions to form soluble nanocomposites of bioelements in the hydrogel pores which can diffuse into the external solution under the action of organic acids of plant origin. Such system of artificial soil provides accelerated growth and increased plants’ productivity
Novel Anion Exchanging Material Based on Silica Gel Covered by Nanolayer of Ferric Oxide / Gromadska L.I., Romanova I.V., Kirillov S.A.// Naukovi visti. - 2012. – N 5. – P. 130–134. Fig. 6. Tabl. 1. Refs.: 18 titles.
Using citrate techniques chemical modification of silica gel surface is carried out by iron oxide in an amount of 0,6 wt. %. Structural characteristics of resulting samples are studied by low-temperature nitrogen desorption and scanning electron microscopy. By utilizing XRD of individual iron oxide we uncover that formation of hematite phase – a-Fe2O3 on the surface of silica gel is most probable. We study hydrolytic stability of modified silica in water interface. We reveal that the process does not depend on pH and that no more than 0.2% of common iron oxide (III) is dissolved in water. Sorption of phosphate ions by modified samples is performed in a wide range of pH, the greatest recovery being 12.2 mg to 1 g of sorbent in terms of iron (III) oxide is about 2,03. Maximum molar ratios of Fe3+:PO3-4 on the surface-modified silica gel is calculated from the value of maximum capacity, which is 1:0,7 in the alkaline and 1:1,7 in slightly acidic solutions. Ratios are close to stoichiometric. They suggest the formation of individual iron phosphates on the silica surface.
The Simulation of Ink Penetration into Paper with Watermarks During Offset Printing / Kyrychok T.Yu., Talimonova N.L., Zaritska V.I.// Naukovi visti. - 2012. – N 5. – P. 135–139. Fig. 5. Refs.: 14 titles.
In this paper, we propose the model of ink fixing on paper with watermarks: properties of positive watermark areas are similar to high-calender paper and properties of areas beyond positive watermark and areas of negative watermark are similar to paper of machine smoothness. It causes difference of ink pigment and binding agent penetration into paper. Colorimetric evaluation of the difference between area of positive watermark and beyond it for offset printed paper with watermark shows the essential distinction: the value of colour shift DE* is 6,5–20,0 and it depends on ink thickness. The technique of preparing paper cross sections is developed relying on microtome cuts. The light microscopic study of paper cross sections demonstrate a big difference of ink penetration depth in zone of positive watermark (9–16 mm) and beyond this zone (22–40 mm). Therefore, through experiments conducted by employing colorimetry as well as microscopic study of printed paper with watermarks cross sections, we prove the feasibility of the proposed model.
The Surface Functionalization of Multiwalled Carbon Nanotubes /Ivanenko I.M., Dontsova T.A., Kondratyuk A.S., Bakalinska O.M. // Naukovi visti. - 2012. – N 5. – P. 140–145. Fig. 10. Tabl. 1. Refs.: 21 titles.
The aim of this paper is to develop methods of oxidation of multiwalled carbon nanotubes (MWCNTs) and determine their functional dependence on oxidation conditions. Based on initial MWCNTs we synthesize three series of samples oxidized under different conditions: by concentrated hydrogen peroxide mixed with sulfuric acid under standard conditions, by concentrated hydrogen peroxide mixed with sulfuric acid during boiling, by concentrated nitrate acid at temperatures of 50, 75 and 100 °C. Functional groups on the MWCNTs surface are qualitatively and quantitatively characterized by Boehm titration method. We discover that treatment of multiwalled carbon nanotubes with concentrated hydrogen peroxide in the sulfuric acid presence under standard conditions for 2–27 hours leads to formation of mainly phenolic groups and a small number of lactones on their surface. However, it does not lead to formation of carboxylic acid groups. Moreover, smaller levels of oxidation can be reached at MWCNTs oxidation by hydrogen peroxide in a mixture of sulfuric acid under reflux for 1–60 minutes than at the same mixture treatment at room temperature. The increase in temperature oxidation contributes to formation of carboxyl groups and does not contribute to formation of lactone groups. The content of phenolic groups prevails in both series of samples.
Application of Computer Modeling to Predict the Chromatographic Analytes Behavior / Levandovskiy І.А.// Naukovi visti. - 2012. – N 5. – P. 146–152. Refs.: 34 titles.
This paper analyzes the capabilities of QSRR. Moreover, we make an insight into brief theoretical information on this method development and provide a list of issues to be solved by dint of it and the issues that may arise during obtaining QSRR models. We present the classification of descriptors and software used in construction of models and a list of basic mathematical algorithms rejecting irrelevant descriptors. The advantages and disadvantages of existing QSRR models used in HPLC method are pointed out. Some examples of the QSRR method application to define differences in mechanisms of analytes separation in comparison of separation capability and classification of chromatographic columns are given. It is shown that prediction of chromatographic behavior of substances in Ag-HPLC may be made both using standard approaches of QSRR method and computer modeling of the interaction between analyte and Ag – stationary phase using modern quantum-chemical methods.
Phase Phase Composition and Melting Features of Mineral Raw Material from Ukrainian Deposits used for LAS-Ceramics Production / Ripenko V.V., Khomenko V.M., Spasonova L.M.// Naukovi visti. - 2012. – N 5. – P. 153–158. Fig. 3. Tabl. 3. Refs.: 12 titles.
This paper describes how Li-glass is obtained and studied. Using this glass, Li2O-Al2O3-SiO2 – based glass-ceramics materials are produced. They play an important role in industry as materials with specific properties. Glass-ceramics materials feature high strength, low coefficient of thermal expansion, chemical and thermal stability, refractoriness etc. To obtain LAS-сeramics, we obtain separate fraction petalite, study their chemical composition, select and calculate the composition of the Li-glass charge. In addition, the heat treatment of the obtained received samples is carried out. Through experiments conducted, we develop methods of obtaining get lithium glass based on mineral raw of Polokhivka mineral deposit (western part of the Kirovograd block of the Ukrainian Shield), investigate phase and chemical composition of obtained samples of mineral fractions and identify their key characteristics, study samples of obtained glass. We make the conclusions concerning the method of preparing components charge of the lithium glass. The results may be used for producing glass-ceramics materials with desired properties based on these glasses.