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Search Results: 1 - 10 of 534699 matches for " T. A. Shelkovenko "
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Observation of neutron emission in the process of X-pinch
O. D. Dalkarov,A. S. Rusetskii,S. A. Pikuz,T. A. Shelkovenko,I. N. Tilikin
Physics , 2015,
Abstract: The results of measuring the neutron flux in the process of the X-pinch are presented. The measurements were carried out using CR-39 track detectors. It was found that in the process of X-pinch recorded neutron emission over a wide energy range (from thermal to energies greater than 10 MeV) with an intensity of more than 108 neutrons per shot into 4{\pi} sr solid angle (assuming isotropy of radiation and localizing the source in the "hot spot"). Data of track detectors suggest that at the time of discharge produced fast neutrons are then slowed down and turned into thermal.
X-Pinches as Broadband Sources of X-Rays for Radiography  [PDF]
Tatiana Shelkovenko, Sergey Pikuz, David Hammer
Journal of Biomedical Science and Engineering (JBiSE) , 2015, DOI: 10.4236/jbise.2015.811071
Abstract: Two methods of using the X-pinch as a source of X-ray radiation for radiography of biological objects are presented. X-pinches are found to be a very flexible method for generation of radiation over a wide spectral range and provide a high spatial and temporal resolution.
Application of the Homotopy Perturbation Method to Nonlinear Heat Conduction and Fractional Van der Pol Damped Nonlinear Oscillator  [PDF]
T. A. Nofel
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.56081

In this paper, a powerful analytical method, called He’s homotopy perturbation method is applied to obtaining the approximate periodic solutions for some nonlinear differential equations in mathematical physics via Van der Pol damped non-linear oscillators and heat transfer. Illustrative examples reveal that this method is very effective and convenient for solving nonlinear differential equations. Comparison of the obtained results with those of the exact solution, reveals that homotopy perturbation method leads to accurate solutions.

Hematocrit and Slip Velocity Influence on Third Grade Blood Flow and Heat Transfer through a Stenosed Artery  [PDF]
A. Jimoh, G. T. Okedayo, T. Aboiyar
Journal of Applied Mathematics and Physics (JAMP) , 2019, DOI: 10.4236/jamp.2019.73046
Abstract: A theoretical investigation concerning hematocrit and slip velocity influence on the flow of blood and heat transfer by taking into account the externally applied magnetic field has been carried out. The mathematical models considered in this work treated blood as a non-Newtonian fluid obeying the third grade fluid model. A suitable geometry of the stenosis is taken into account. Galerkin weighted residual and Newton Raphson methods are used to solve the equations that govern the flow of blood and heat transfer. Analytical expression for the velocity profile, temperature profile, volume flow rate, wall shear stress and resistance to flow were obtained. Graphical representation of results shows that the flow velocity, volumetric flow rate and shear stress increase while resistance to flow and heat transfer rate decrease when the slip velocity increases. Also, flow velocity and volume flow rate decrease while shear stress, heat transfer rate, and resistance to flow increase when the hematocrit parameter increases. Finally, increases in magnetic field parameter lead to decrease in flow velocity, flow rate and shear stress but increase the flow resistance.
Exact Solution for Pressure Driven Flow of Two Immiscible Phan-Thien-Tanner Fluids in a Pipe  [PDF]
A. M. Siddiqui, A. Walait, T. Allison, T. Haroon
Open Journal of Fluid Dynamics (OJFD) , 2018, DOI: 10.4236/ojfd.2018.84024
Abstract: This paper provides the exact solutions for the fully developed two layer pressure driven flows of incompressible Phan-Thien-Tanner fluids in a horizontal cylindrical pipe. Exact equations are formulated and solved for important kinematic properties, such as, velocity profiles, normal and shear stresses, total volume fluxes through a circular cross-section and average velocities. Graphical results are provided and discussed for the different flow parameters. A comparison of Upper Convected Maxwell (UCM), Linear Phan-Thien-Tanner (LPTT) and Exponential Phan-Thien-Tanner (EPTT) shows that UCM is a low viscosity fluid as compared to LPTT, and EPTT and LPTT is lighter than EPTT.
Self-Adaptive DE Applied to Controller Design  [PDF]
K. A. Folly, T. Mulumba
Journal of Computer and Communications (JCC) , 2014, DOI: 10.4236/jcc.2014.29007

Adequate damping is necessary to maintain the security and the reliability of power systems. The most-cost effective way to enhance the small-signal of a power system is to use power system controllers known as power system stabilizers (PSSs). In general, the parameters of these controllers are tuned using conventional control techniques such as root locus, phase compensation techniques, etc. However, with these methods, it is difficult to ensure adequate stability of the system over a wide range of operating conditions. Recently, there have been some attempts by researchers to use Evolutionary Algorithms (EAs) such as Genetic Algorithms (GAs), Particle Swarm Optimization, Differential Evolution (DE), etc., to optimally tune the parameters of the PSSs over a wide range of operating conditions. In this paper, a self-adaptive Differential Evolution (DE) is used to design a power system stabilizer for small-signal stability enhancement of a power system. By using self-adaptive DE, the control parameters of DE such as the mutation scale factor F and cross-over rate CR are made adaptive as the population evolves. Simulation results are presented to show the effectiveness of the proposed approach.

The Barrier Properties of Flake-Filled Composites with Precise Control of Flake Orientation  [PDF]
A. Tsiantis, T. D. Papathanasiou
Materials Sciences and Applications (MSA) , 2017, DOI: 10.4236/msa.2017.83016
Abstract: Additive manufacturing, especially in the form of 3D printing, offers the exciting possibility of generating heterogeneous articles with precisely controlled internal microstructure. One area in which this feature can be of significant advantage is in diffusion control, specifically in the design and fabrication of microstructures which optimize the rate of transport of a solute to and from a contained fluid. In this work we focus on the use of flakes as diffusion-control agents and study computationally and theoretically the effect of orientation on the barrier properties of flake-filled composites. We conducted over 1500 simulations in two-dimensional, doubly-periodic unit cells each containing up to 3000 individual flake cross-sections which are randomly placed and with their axes forming an angle (\"\") with the direction of macroscopic diffusion. We consider long-flake systems of aspect ratio (\"\") 100 and 1000, from the dilute (\"\") and into the concentrated (\"\") regime. Based on the rotation properties of the diffusivity tensor, we derive a model which is capable of accurately reproducing all computational results (\"\" and \"\"). The model requires as inputs the two principal diffusivities of the composite, normal and parallel to the flake axis. In this respect, we find the models of Lape et al. [1] and Nielsen [2] form an excellent combination. Both our model and our computational data predict that at \"\" the quadratic dependence of the Barrier Improvement Factor (BIF) on (\"\") is lost, with the BIF approaching a plateau at higher values of (\"\"). This plateau is lower as (\"\") increases. We derive analytical estimates of this maximum achievable BIF at each level of misalignment; these are also shown to be in excellent agreement with the computational results. Finally we show that our computational results and model are in agreement with experimental evidence at small values of
Estimation of Annual Effective Dose Due to Ingestion of Natural Radionuclides in Cattle in Tin Mining Areas of Jos Plateau, Nigeria: Are Large Mammals Really Affected?  [PDF]
A. S. Aliyu, T. A. Mousseau, N. N. Garba, H. T. Abba, A. T. Ramli
Natural Science (NS) , 2015, DOI: 10.4236/ns.2015.74022
Abstract: We have read with great interest the paper which was published in Natural Science, 2014 issue number 6 titled “Estimation of annual effective dose due to ingestion of natural radionuclides in cattle in tin mining area of Jos Plateau, Nigeria” [1]. The paper motivated us to use state-of-the-art computational technique to investigate the risks of the tin mining activity in Jos-Plateau, Nigeria on large mammals (e.g. cattle). The Tier 2 Erica Tool assessment was used to estimate the total dose rate and risk quotients of these reference terrestrial animals. Our investigation revealed that the expected and conservative risk quotients of large mammals due to internal and external exposure to enhanced level of radioactivity are 0.05 and 0.16, respectively. Since the risk quotients are less than unity, this indicates that there is less than 5% probability that the screen dose rate (10 μGyh1) is exceeded. The estimated total dose rate to large mammals is 0.52 μGyh1 which is not statistically significant. A critical analysis of [1] is presented in the introductory part of this paper.
Research of Network Transient Performance at Small Perturbations  [PDF]
T. A. Makhkamov, A. M. Mirzabaev
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B129

The advisability of the use of matrix methods of equations rearrangement for the investigated system which allows writing a secular equation is considered in this article. This approach greatly simplifies the analysis of performance of transient response in complicated multi-coupled electrical system at small perturbations.

The Use of Indigenous Language in Radio Broadcasting: A Platform for Language Engineering  [PDF]
T. A. Akanbi, O. A. Aladesanmi
Open Journal of Modern Linguistics (OJML) , 2014, DOI: 10.4236/ojml.2014.44049
Abstract: This paper discusses the practical ways by which language users make use of coinage in order to find expressions for the day-to-day usages of common words, but which albeit are found in other languages like English. The media practitioners are exposed to using words to capture their intensions. Since these practitioners are faced with audience that are of local language, they are constrained to look for words that will express what goes on in the world around them. In an age of Information and Communications Technology (ICT), many of the words used are computer compliant, therefore, it behoves the people interacting with the populace through language to look for those codes that will carry their messages to their audience in the way that will go in conformity to the understanding of their audience. This paper, therefore, looks at those coinages and proposes that they should be collated and integrated into Yorùbaá vocabulary system for the use of people in a general context.
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