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Search Results: 1 - 10 of 461903 matches for " A. Lyashenko "
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Efficient Methods for Fast Shading
ROMANYUK, A.,HAST, A.,LYASHENKO, Y.
Advances in Electrical and Computer Engineering , 2008,
Abstract: On devices without battery consuming and specialized hardware for rendering, it is important to improve the speed and quality so that these methods are suitable for real-time rendering. Furthermore such algorithms are needed on the coming multicore architectures. We show how the methods by Gouraud and Phong, the commonly most used methods for shading, can be improved and made faster for both software rendering as well as simple low energy consuming hardware implementations. Moreover, this paper summarizes the authors' achievements in increasing shading speed and performance and a Bidirectional Reflectance Distribution Function is simplified for faster computing and hardware implementation.
Stick-Slip Mode of Boundary Friction as the First-Order Phase Transition
I. A. Lyashenko,A. M. Zaskoka
Physics , 2013,
Abstract: A tribological system consisting of two contacting blocks has been considered. One of them is arranged between two springs, the other is driven periodically. The kinetics of the system has been studied in the boundary friction mode, when an ultrathin lubricant film is contained between the atomically smooth surfaces. In order to describe the film state, the expression for the free energy density is used in the form of an expansion in a power series in the order parameter, the latter being reduced to the shear modulus of a lubricant. The stick-slip mode is shown to be realized in a wide range of parameters, being a result of the periodic first-order phase transitions between kinetic friction regimes. The behavior of the system governed by internal and external parameters has been predicted.
Hysteresis phenomena at ultrathin lubricant film melting in the case of first-order phase transition
A. V. Khomenko,I. A. Lyashenko
Physics , 2006, DOI: 10.1016/j.physleta.2007.02.010
Abstract: Within the framework of Lorentz model for description of viscoelastic medium the influence of deformational defect of the shear modulus is studied on melting of ultrathin lubricant film confined between the atomically flat solid surfaces. The possibility of jump-like and continuous melting is shown. Three modes of lubricant behavior are found, which correspond to the zero shear stress, the Hooke section of loading diagram, and the domain of plastic flow. Transition between these modes can take place according to mechanisms of first-order and second-order phase transitions. Hysteresis of dependences of stationary stresses on strain and friction surfaces temperature is described. Phase kinetics of the system is investigated. It is shown that ratio of the relaxation times for the studied quantities influences qualitatively on the character of the stationary mode setting.
Analysis of the stability of stationary boundary friction modes in the framework of a synergetic model
Iakov A. Lyashenko,Nataliia N. Manko
Physics , 2014,
Abstract: A synergetic model describing the state of an ultrathin lubricant layer squeezed between two atomically smooth solid surfaces operating in the boundary friction mode has been developed further. To explain the presence of different operation modes of the system for various sets of its main parameters, the mathematical analysis of the synergetic model is carried out. The type of functioning a tribological system is described in accordance with the stability character of singular points, and the diagrams distinguishing various operation modes are obtained. Phase portraits corresponding to different stability types are plotted for all diagram areas. A stick-slip mode of motion that is often observed experimentally is described.
THE FILLING PILE SETTLEMENT PROCESS INVESTIGATION Исследование на модели развития осадки буронабивной сваи
Lyashenko P. A.,Shmidt O. A.,Gokhaev D. V.
Polythematic Online Scientific Journal of Kuban State Agrarian University , 2013,
Abstract: The filling piles and their joint work with soil are the objects of research. The joint working of filling piles and soil has been researched with the constant rate of loading (CRL) and the continuous measuring of deformations of physical model. The experiment was realized at the physical model of filling pile in soil with the apparatus AKP-6NM. The hypothesis of mechanical working of near-pile soil was proposed as the result of the experiment
THE STUDY OF PRECONSOLIDATION PRES-SURE OF LOAMY SOIL WITH THE CONSTANT RATE OF LOADING Изучение структурной прочности глинистого грунта при постоянно возрастающей нагрузке
Lyashenko P. A.,Denisenko V. V.,Belyaeva Y. A.
Polythematic Online Scientific Journal of Kuban State Agrarian University , 2012,
Abstract: The preconsolidation pressure of natural loamy soils was researched with the method of constant rate of loading (CRL) and the continuous measuring of de-formations at the apparatus AKP-6NM. The results of the rate of deformation analysis have been offered. The method of the preconsolidation pressure and the crumple pressure values has been suggested based on the rate of deformation analysis
Multifractal analysis of stress time series during ultrathin lubricant film melting
A. V. Khomenko,I. A. Lyashenko,V. N. Borisyuk
Physics , 2010, DOI: 10.1142/S0219477510000046
Abstract: Melting of an ultrathin lubricant film confined between two atomically flat surfaces is we studied using the rheological model for viscoelastic matter approximation. Phase diagram with domains, corresponding to sliding, dry, and two types of $stick-slip$ friction regimes has been built taking into account additive noises of stress, strain, and temperature of the lubricant. The stress time series have been obtained for all regimes of friction using the Stratonovich interpretation. It has been shown that self-similar regime of lubricant melting is observed when intensity of temperature noise is much larger than intensities of strain and stress noises. This regime is defined by homogenous distribution, at which characteristic stress scale is absent. We study stress time series obtained for all friction regimes using multifractal detrended fluctuation analysis. It has been shown that multifractality of these series is caused by different correlations that are present in the system and also by a power-law distribution. Since the power-law distribution is related to small stresses, this case corresponds to self-similar solid-like lubricant.
Thermodynamics and kinetics of boundary friction
I. A. Lyashenko,A. V. Khomenko,L. S. Metlov
Physics , 2010, DOI: 10.1016/j.triboint.2010.12.005
Abstract: A deterministic theory describing the behavior of an ultrathin lubricant film between two atomically-smooth solid surfaces is proposed. For the description of lubricant state the parameter of excess volume arising due to chaotization of solid medium structure in the course of melting is introduced. Thermodynamic and shear melting is described consistently. Dependences of friction force on temperature of lubricant, shear velocity of rubbing surfaces, and pressure upon surfaces are analyzed. Within the framework of a simple tribological model the stick-slip mode of friction, when the lubricant periodically melts and solidifies, is described. The obtained results are qualitatively compared with the experimental data.
Multidimensional thermodynamic potential for descriptions of ultrathin lubricant film melting between two atomically smooth surfaces
L. S. Metlov,A. V. Khomenko,I. A. Lyashenko
Physics , 2009, DOI: 10.5488/CMP.14.13001
Abstract: The thermodynamic model of ultrathin lubricant film melting, confined between two atomically-flat solid surfaces, is built using the Landau phase transition approach. Non-equilibrium entropy is introduced describing the part of thermal motion conditioned by non-equilibrium and non-homogeneous character of the thermal distribution. The equilibrium entropy changes during the time of transition of non-equilibrium entropy to the equilibrium subsystem. To describe the condition of melting, the variable of the excess volume (disorder parameter) is introduced which arises due to chaotization of a solid structure in the course of melting. The thermodynamic and shear melting is described consistently. The stick-slip mode of melting, which is observed in experiments, are described. It is shown that with growth of shear velocity, the frequency of stiction spikes in the irregular mode increases at first, then it decreases, and the sliding mode comes further characterized by the constant value of friction force. Comparison of the obtained results with experimental data is carried out.
Phenomenological Theory of Boundary Friction in the Stick-Slip Mode
I. A. Lyashenko,A. V. Khomenko,L. S. Metlov
Physics , 2011,
Abstract: A deterministic theory describing the melting of an ultrathin lubricant film between two atomically smooth solid surfaces has been developed. The lubricant state is described by introducing a parameter of excess volume that arises owing to the solid structure chaotization at its melting. The thermodynamic and shear kinds of melting are described consistently. The dependences of the stationary friction force on the lubricant temperature and the shear velocity of rubbing surfaces that move with respect to each other with a constant velocity have been analyzed. In the framework of a simple tribological model, the stick-slip mode of friction, when the lubricant periodically melts and solidifies, has been described. The influence of velocity, temperature, and load on the stick-slip friction has been analyzed. A qualitative comparison between the results obtained and experimental data has been carried out.
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