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Search Results: 1 - 10 of 8300 matches for " Victor Egorovitch Firstov "
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Semantic model and optimization of creative processes at mathematical knowledge formation  [PDF]
Victor Egorovitch Firstov
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.28113
Abstract: The aim of this work is mathematical education through the knowledge system and mathematical modeling. A net model of formation of mathematical knowledge as a deductive theory is suggested here. Within this model the formation of deductive theory is represented as the development of a certain informational space, the elements of which are structured in the form of the orientated semantic net. This net is properly metrized and characterized by a certain system of coverings. It allows injecting net optimization parameters, regulating qualitative aspects of knowledge system under consideration. To regulate the creative processes of the formation and realization of mathematical know- edge, stochastic model of formation deductive theory is suggested here in the form of branching Markovian process, which is realized in the corresponding informational space as a semantic net. According to this stochastic model we can get correct foundation of criterion of optimization creative processes that leads to “great main points” strategy (GMP-strategy) in the process of realization of the effective control in the research work in the sphere of mathematics and its applications.
Fluid Dynamic Response of the Russia Seismically Differing Regions to the Global Geodynamics Processes  [PDF]
Valera P. Rudakov, Pavel P. Firstov, Vladislav V. Tsyplakov
International Journal of Geosciences (IJG) , 2012, DOI: 10.4236/ijg.2012.34077
Abstract: The results of the spectral-correlation analysis of the fluid-dynamic (radon and hydrogen) data monitoring obtained in the seismically active region—on Kamchatka and in conditions of Russian platform where compared to the results of the laser-deformometer measurements obtained on Caucasus. It allowed identify spectral components of the measured parameters, first of all, in the area of the lunar-solar tides. This identification have demonstrated the identical reaction of the mountain and platform regions to the global geodeformation processes of the tidal level and have shown the possibility of the measuring parameters response to the catastrophic events preparation processes. Really the prognostic effects in the investigated fields where indicated in periods of preparation and realization of the catastrophic earthquakes in Indian Ocean on December, 26, 2004 and on March, 28, 2005.
High-temperature short-term and long hardness of sintered compact and porous titanium-siliceous carbide ti3sic2
Firstov S.A.,Pechkovsky E.P.
Science of Sintering , 2004, DOI: 10.2298/sos0401011f
Abstract: The ternary compound of titanium-siliceous carbide Ti3SiC2, one of the representatives of Nan laminates, prepared by solid-phase sintering is investigated in compact and porous (q=0.03-0.41) states. Features of its short-term and long-term hardness (Р=10 N) behavior in the temperature range from 20 to 1200 С at a holding time of 1-60 min were studied. It is shown that a temperature of about 700°С and holding time under load of about 10 min are critical values of the indentation procedure that correspond to an intensive decrease of hardness. The presence of porosity results in a decrease in hardness. a deformation scheme of compact and porous titanium-siliceous carbide Ti3SiC2 in the temperature range from 20 to 1200 С is proposed. .
Critical grain sizes and generalized flow stress - grain size dependence
S. A. Firstov,T. R. Rogul,O. A. Shut
Physics , 2013,
Abstract: The generalized eguation that describes the yield stress dependence upon the grain size in the wide range of grain sizes has been obtained. There are two critical grain sizes that corresponds to the changes in strengthening mechanism. The equation includes Hall - Petch relation in the range of d>dcr1. For dcr1>d>dcr2, the power in the Hall - Petch relation varies from -1/2 to -1. In a nanometer (nm) range (d
Properties of Coatings Deposited from Filtered Vacuum Arc Plasma with HEA Cathode
Kuprin A.S.,Belous V.A.,Firstov S.A.,Gorban V.F.
Proceedings of the International Conference Nanomaterials : Applications and Properties , 2013,
Abstract: Ti V Zr Nb Hf metallic and nitride films were deposited by filtered vacuum arc plasma from a single equiatomic HEA cathode. The composition, microstructure, mechanical properties, thermal stability and corrosion properties were investigated. The deposited metallic film has a two-phase structure with bcc and hcp-lattice. The nitride films were found to have only an fcc structure. All coatings have nano-grained structures, with grain sizes 5 nm for metallic and 36 nm for nitride. The nitride coatings have a compressive stress of around -12,5 GPa, high hardness ~ 40 GPa and elastic modulus ~ 450 GPa. After annealing in vacuum in range 400 – 1200 °C, 3 h for every temperature, hardness decreased to 25 GPa. It was found that both the metallic and nitride coatings exhibited their best corrosion resistance than steel samples in a 3,5 wt.% NaCl solution. The metallic coatings showed better corrosion resistance than the nitride coatings
Effects of Deuterium Implantation Dose on Hardness and Deuterium Desorption
Kuprin A.S.,Morozov O.M.,Belous V.A.,Firstov S.A.
Proceedings of the International Conference Nanomaterials : Applications and Properties , 2013,
Abstract: High entropy TiVZrNbHf and TiVZrNbHfN coatings prepared by filtered vacuum arc plasma from a single equiatomic HEA cathode. Similarly were obtained titanium and titanium nitride coatings. The structure of coatings was investigated by X-ray analysis and the changes in nanohardness by nanoindentation method. The effusion of the implanted deuterium was studied by thermal desorption spectroscopy (TDS). It is shown that the structure of effusion spectrum is a function of deuterium dose. With increasing implantation dose deuterium desorption temperature range from coatings is expanding in the direction of lowering the temperature and the temperature of the peak maximum gas emission gradually shifts to lower temperatures. For nitride coatings deuterium desorption starts at about room temperature and the maximum rate of desorption at a temperature of ~500 K. When irradiation doses more than 5×1017 D/cm2 hardness of nitride coatings decreased by half. Hardness reduction of coatings is caused by occurrence hydride structural formations in coatings.
The nexus of soil radon and hydrogen dynamics and seismicity of the northern flank of the Kuril-Kamchatka subduction zone
P. P. Firstov,V. S. Yakovleva,V. A. Shirokov,O. P. Malysheva
Annals of Geophysics , 2007, DOI: 10.4401/ag-3068
Abstract: The comparison of kinematics and dynamic parameters of radon and molecular hydrogen concentration in subsoil air on the stations network at the Petropavlovsk-Kamchatsky geodynamic proving ground with seismicity of the northern flank of the Kuril-Kamchatka subduction zone was fulfilled in the period from July till August 2004. On the basis of correlation analysis of the regional seismicity and variations of radon flux density calculated using the data of gas-discharge counters of STS-6 type and SSNTDs it was shown that the radon mass transfer abnormal variations are conditioned by both regional seismicity in total and the subduction zone of proving ground. The azimuths of geodeformation waves coming to the registration points are calculated during clearly expressed anomaly beginnings, which coincide with directions to earthquake epicenters taking place at the same time. The geochemical anomalies recorded are presumptively deformative by nature and can be conditioned by processes of quasi-viscous flow of the lithosphere during rearrangement of tectonic stress fields of the subduction zone. The short-term (predicted time ? <14 days) precursor of the earthquakes swarm was revealed in hydrogen dynamics on August, 4-5 (four earthquakes had M?5.3 and epicentral distance about 130 km from the Paratunka base station).
The Analysis of Accelerograms for the Earthquake Resistant Design of Structures  [PDF]
Victor Corchete
International Journal of Geosciences (IJG) , 2010, DOI: 10.4236/ijg.2010.11004
Abstract: In this paper, the analysis of ground motions (displacements, velocities and accelerations) has been performed focused to the seismic design. The relationships between the peak ground acceleration (PGA), the peak ground velocity (PGV), the peak ground displacement (PGD) and the bracketed duration, with the earthquake magnitude, are presented and their validity and applicability for seismic design is discussed. Finally, the dominant periods of the ground motions (displacement, velocity and acceleration) are obtained from their Fourier Spectrum. Their validity and applicability for the seismic design is discussed also. The results presented in this paper show that the relationships that exist between the important parameters: PGA, PGV, PGD and duration; and the earthquake magnitude, allow the prediction of the values for these parameters, in terms of the magnitude for future strong motions. These predictions can be very useful for seismic design. Particularly, the prediction of the magnitude associated to the critical acceleration, because the earthquakes with magnitude greater than this critical magnitude can produce serious damages in a structure (even its collapsing). The application of the relationships obtained in this paper must be very careful, because these equations are dependent on the source area, location and type of structure. The dominant periods of the ground motions (displacement, velocity and acceleration) that are computed and presented in this paper, are also important parameters for the seismic design, because recent studies have shown that the earthquake shaking is more destructive on structures having a natural period around some of these dominant periods. These parameters must also be handled with caution, because they show dependence with the source area, location and type of structure.
The SAFEX-JIBAR Market Models  [PDF]
Victor Gumbo
Journal of Mathematical Finance (JMF) , 2012, DOI: 10.4236/jmf.2012.24035
Abstract: It is possible to construct an arbitrage-free interest rate model in which the LIBOR rates follow a log-normal process leading to Black-type pricing formulae for caps and floors. The key to their approach is to start directly with modeling observed market rates, LIBOR rates in this case, instead of instantaneous spot rates or forward rates. This model is known as the LIBOR Market Model. We formulate the SAFEX-JIBAR market model based on the fact that the forward JIBAR rates follow a log-normal process. Formulae of the Black-type are deduced.
Wave Equation Simulation Using a Compressed Modeler  [PDF]
Victor Pereyra
American Journal of Computational Mathematics (AJCM) , 2013, DOI: 10.4236/ajcm.2013.33033
Abstract:

Repeated simulations of large scale wave propagation problems are prevalent in many fields. In oil exploration earth imaging problems, the use of full wave simulations is becoming routine and it is only hampered by the extreme computational resources required. In this contribution, we explore the feasibility of employing reduced-order modeling techniques in an attempt to significantly decrease the cost of these calculations. We consider the acoustic wave equation in two-dimensions for simplicity, but the extension to three-dimensions and to elastic or even anysotropic problems is clear. We use the proper orthogonal decomposition approach to model order reduction and describe two algorithms: the traditional one using the SVD of the matrix of snapshots and a more economical and flexible one using a progressive QR decomposition. We include also two a posteriori error estimation procedures and extensive testing and validation is presented that indicates the promise of the approach.

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