Monday, February 14. 2022
Andrii Chugaia, Svitlana Alyokhina a,b, and Andrii Zhuravkab
a Institute for Mechanical Engineering Problems of the National Academy of Sciences of Ukraine, 2/10
Pozharskogo st., Kharkiv 61046, Ukraine, e-mail: alyokhina@ipmach.kharkov.ua
b Kharkiv National University of Radioelectronics, 14 Nauky ave., Kharkiv 61166, Ukraine
The paper is concerned to the development of an approach which allow us for solving the layout problem of container with spent nuclear fuel on the storage site to apply methods of geometric design. An exact mathematical model of optimal layout problem of spent nuclear fuel containers in the storage site is constructed. Due to phi-function technique the mathematical model is constructed as a non-linear mathematical programing problem. The features of the mathematical model are presented. It is shown that the feasible solution region can be presented as a union of subregion. Each of the subregion is described by systems of inequalities which the left parts are continuous functions. On the bases of features the solution approach is proposed.
Keywords: mathematical modeling, phi-function, NP-hard problem, spent nuclear fuel, layout problems, nuclear safety
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Thursday, January 13. 2022
FAZEL HADADIFARD, SATBIR MALHI, AND ZHENGYI XIAO
Abstract. In this paper, a class of finite difference numerical techniques is presented to solve the second-order linear inhomogeneous damped wave equation. The consistency, stability, and convergences of these numerical schemes are discussed. The results obtained are compared to the exact solution, ordinary explicit, implicit finite difference methods, and the fourth-order compact method (FOCM). The general idea of these methods is developed by using C0-semigroups operator theory. We also showed that the stability region for the explicit finite difference scheme depends on the damping coefficient.
c 2022 European Society of Computational Methods in Sciences and Engineering
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Monday, March 8. 2021
Beny Neta ∗
Naval Postgraduate School
Department of Applied Mathematics
Monterey, CA 93943
e-mail: bneta@nps.edu, Tel: 1-831-656-2235, Fax: 1-831-656-2355
Received 01/02/2020, Revised 10/12/2020, Accepted 02/03/2021
Abstract: A new trigonometrically-fitted method of order 12 is developed and compared to an existing P-stable method of the same order. Our method fit exactly the sine and cosines functions sin(rωx), cos(rωx), r = 1,2 and monomials up to degree 9. Our method is tested on several linear and nonlinear examples to demonstrate its accuracy and sensitivity to perturbation in the known frequency. We also show where it is preferable to use the trigonometrically-fitted method. Our method shows its efficiency in solving a nonlinear equation both in terms of global accuracy and CPU run time.
c 2021 European Society of Computational Methods in Sciences and Engineering
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Monday, February 1. 2021
S.A. Khuri1, I. Louhichi, A. Sayfy
Department of Mathematics and Statistics, American University of Sharjah - UAE
Received 14 January, 2019; accepted in revised form 26 January, 2021
Abstract: In this article, we study a fixed point iteration scheme that involves the Green’s function for the numerical solution of a larger class of fourth order boundary value problems (BVPs). The scheme enjoys important features such as its high accuracy, reliability, and fast convergence. We analyze and prove convergence of the iterative procedure using the contraction principle. Several numerical examples of fourth order boundary value problems are used to test the proposed method. The numerical results clarify very good agreement with the exact solution and superiority of this approach when compared with other numerical results that exist in the literature. Furthermore, the method requires less CPU time than other techniques.
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Saturday, December 12. 2020
Research of Integrated Passive Methods of Heat Dissipation Intensification to Improve the Efficiency of Gas-Dynamic Temperature Stratification
Е.V. Tsvetova, V.N. Kovalnogov, R.V. Fedorov
Department of Heat and Power Engineering, Ulyanovsk State Technical University, Severny Venets str. 32, Ulyanovsk, 432027, Russia © European Society of Computational Methods in Sciences and Engineering Keywords: numerical simulation, gas-dynamic temperature stratification, dispersion flow, heat transfer coefficient, developed surfaces Mathematics Subject Classification: 65R20 Numerical methods for integral equations
Received: 04/09/2020, Revised: 20/10/2020, Accepted: 05/12/2020
Abstract: A possibility was analyzed to increase the efficiency of the gas-dynamic temperature stratification process through the use of complex passive methods of heat transfer intensification: developed surfaces - longitudinal fins on the heat transfer surface in the subsonic flow path; additives to the gas flow of the disperse phase with a twisting flow.
PACS: 02.60.Cb Numerical simulation; solution of equations
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Saturday, December 12. 2020
Numerical Simulation and Investigation of the Influence of the Characteristics of the Building Envelope on Energy Efficiency and Energy Saving Potential
Yu.E. Chamchiyan, V.N. Kovalnogov, R.V. Fedorov
Department of Heat and Power Engineering, Ulyanovsk State Technical University, Severny Venets str. 32, Ulyanovsk, 432027, Russia
Received: 03/09/2020, Revised: 15/10/2020, Accepted: 08/12/2020
Abstract: The heat engineering characteristics of external enclosing structures and their influence on the microclimate of the building are analyzed. Potential spheres in the field of providing microclimate for energy saving are considered. The potential for savings in the implementation of automated regulation of microclimate systems is presented.
© European Society of Computational Methods in Sciences and Engineering Keywords: numerical simulation, numerical methods, energy efficiency, energy saving, microclimate. Mathematics Subject Classification: 65R20 Numerical methods for integral equations
PACS: 02.60.Cb Numerical simulation; solution of equations
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Saturday, December 12. 2020
Influence of the Air Swirling Speed on the Processes of Joint Combustion of the Fuel-Air Mixture in the Active Combustion Zone of Power Plants
R.V. Fedorov, A.V. Chukalin, V.N. Kovalnogov, U.J. Mizher, M.M. Zamaleev
Department of Heat and Power Engineering,
Ulyanovsk State Technical University, Severny Venets str. 32, Ulyanovsk, 432027, Russia
Received: 01/09/2020, Revised: 15/10/2020, Accepted: 07/12/2020
Abstract: The search for new solutions in the field of energy, preventing negative impact on the environment, is one of the priority tasks for modern society. It is natural gas that has a stable position in the demand of the UES of Russia for fossil fuel. One of the promising areas is the use of biogas as a source of thermal energy for power plants. It has been established that the main difference between biogas and natural gas, which affects the density, calorific value, and speed of flame propagation, is caused by the presence of more than 30% carbon dioxide in its composition. Combined combustion of natural gas and biogas, subject to good mixing due to the tangentially swirling apparatus of the fuel-air mixture, can increase the stability of biogas combustion, reduce the maximum adiabatic temperature in the zone of active combustion of power boilers of TPPs, which in turn will lead to a decrease in the content of NOx, CO2 in products combustion. For the combustion of biogas at the power plants in operation at TPPs of the UES of Russia, it is important to carry out, on the basis of the theoretical data obtained on the effective combustion modes of fuels, the technical re-equipment of the burners. The paper presents a turbulence model k – ε RNG, which makes it possible to simulate the combustion of natural gas and biogas during tangential swirling of the air-fuel mixture. The qualitative characteristics of biogas, the quantitative content of NOx, CO2 in the combustion products, the temperature distribution in the zone of active combustion of fuel combinations - natural gas, biogas, natural gas / biogas is presented.
© European Society of Computational Methods in Sciences and Engineering Keywords: Numerical simulation, modeling, biogas, co-combustion, efficiency, emission reduction Mathematics Subject Classification: 65R20 Numerical methods for integral equations PACS: 02.60.Cb Numerical simulation; solution of equations
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