Haresh Kumar Sharma, Kriti Kumari, Samarjit Kar

Intelligent Automation & Soft Computing, Vol.25, No.1, pp. 1-14, 2019, DOI:10.31209/2018.100000036

Abstract This article focuses on the use of the rough set theory in modeling of time series forecasting. In this paper, we have used the double exponential smoothing (DES) model for forecasting. The classical DES model has been improved by using the rough set technique. The improved double exponential smoothing (IDES) method can be used for the time series data without any statistical assumptions. The proposed method is applied on tourism demand of the air transportation passenger data set in Australia and the results are compared with the classical DES model. It has been observed that the forecasting accuracy of the… More >

Rafael Company¹, Vera N. Egorova², Lucas Jódar^1,*, Ferran Fuster Valls³

CMES-Computer Modeling in Engineering & Sciences, Vol.124, No.2, pp. 493-508, 2020, DOI:10.32604/cmes.2020.010208

Abstract A numerical method for American options pricing on assets under the Heston stochastic volatility model is developed. A preliminary transformation is applied to remove the mixed derivative term avoiding known numerical drawbacks and reducing computational costs. Free boundary is treated by the penalty method. Transformed nonlinear partial differential equation is solved numerically by using the method of lines. For full discretization the exponential time differencing method is used. Numerical analysis establishes the stability and positivity of the proposed method. The numerical convergence behaviour and effectiveness are investigated in extensive numerical experiments. More >

Mohamed Abd El-Aziz^{1, 2}, A. M. Aly^{1, 3, *}

CMC-Computers, Materials & Continua, Vol.62, No.2, pp. 525-549, 2020, DOI:10.32604/cmc.2020.08576

Abstract This study focusses on the numerical investigations of boundary layer flow for magnetohydrodynamic (MHD) and a power-law nanofluid containing gyrotactic microorganisms on an exponentially stretching surface with zero nanoparticle mass flux and convective heating. The nonlinear system of the governing equations is transformed and solved by Runge-Kutta-Fehlberg method. The impacts of the transverse magnetic field, bioconvection parameters, Lewis number, nanofluid parameters, Prandtl number and power-law index on the velocity, temperature, nanoparticle volume fraction, density of motile microorganism profiles is explored. In addition, the impacts of these parameters on local skin-friction coefficient, local Nusselt, local Sherwood numbers and local density number… More >

Mohamed Abd El-Aziz^{1, 2}, A. M. Aly^{1, 3, *}

CMC-Computers, Materials & Continua, Vol.62, No.1, pp. 37-59, 2020, DOI:10.32604/cmc.2020.08488

Abstract In the present study, the effects of the magnetic field on the entropy generation during fluid flow and heat transfer of a Sisko-fluid over an exponentially stretching surface are considered. The similarity transformations are used to transfer the governing partial differential equations into a set of nonlinear-coupled ordinary differential equations. Runge-Kutta-Fehlberg method is used to solve the governing problem. The effects of magnetic field parameter M, local slip parameter λ, generalized Biot number γ, Sisko fluid material parameter A, Eckert number Ec, Prandtl number Pr and Brinkman number Br at two values of power law index on the velocity, temperature,… More >

Liu XL^1,2, JH Li^2,3, JY Zhu², YF Yang¹

Phyton-International Journal of Experimental Botany, Vol.85, pp. 297-304, 2016, DOI:10.32604/phyton.2016.85.297

Abstract Spring ephemeroid plants complete their aboveground reproduction and growth during the short growing season, and may go dormant subsequently underground. Little is known about the underground dormancy and biological activities of the plants. In this study, we observed organogenesis and growth rhythm of rhizome buds of Adonis amurensis Regel et Radde, a spring ephemeroid plant from the Changbai Mountains in northeastern China. Our results showed that A. amurensis did not go through summer dormancy, but started producing mixed buds on rhizomes soon after the aboveground parts had died. The buds grew in length and diameter following an exponential model with… More >

Weichung Yeih, Chia-Min Fan, Zen-Chin Chang,Chen-Yu Ku

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.2, pp. 43-44, 2011, DOI:10.3970/icces.2011.020.043

Abstract In this paper, the Cauchy problem of the nonlinear steady-state heat conduction is solved by using the polynomial expansion method and the exponentially convergent scalar homotopy method (ECSHA). The nonlinearity involves the thermal dependent conductivity and mixed boundary conditions having radiation term. Unlike the regular boundary conditions, Cauchy data are given on part of the boundary and a sub-boundary without any information exists in the formulation. We assume that the solution for a two-dimensional problem can be expanded by polynomials as: where T is the temperature distribution, np is the maximum order of polynomial expansion, x and y are Cartesian… More >

Chung-Lun Kuo, Chein-Shan Liu, Jiang-Ren Chang

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.2, pp. 35-36, 2011, DOI:10.3970/icces.2011.019.035

Abstract In this study, the exponentially convergent scalar homotopy algorithm (ECSHA) is proposed to solve the nonlinear optimization problems under equality and inequality constraints. The Kuhn-Tucker optimality conditions associated with NCP-functions are adopted to transform the nonlinear optimization problems into a set of nonlinear algebraic equations. Then the ECSHA is used to solve the resultant nonlinear equations. The proposed scheme keeps the merit of the conventional homotopy method, such as global convergence, but the inverse of the Jacobian matrix is avoid with the aid of the scalar homotopy function. Several numerical examples are provided to demonstrate the efficiency of the proposed… More >

H.F. Chan, C.M. Fan

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.1, pp. 29-30, 2011, DOI:10.3970/icces.2011.019.029

Abstract The inverse boundary optimization problem, which is governed by Helmholtz equation, is analyzed by the modified collocation Trefftz method (MCTM) and the exponentially convergent scalar homotopy algorithm (ECSHA). In the inverse boundary optimization problem, the position for part of boundary with given boundary condition is unknown, and the position for the rest of boundary with additionally specified boundary conditions is given. Therefore, it is very difficult to handle the boundary optimization problem by any numerical scheme. In order to stably solve the boundary optimization problem, the MCTM, one kind of boundary-type meshless methods, will be adopted in this study, since… More >

K. Kakuda¹, Y. Maeda¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.14, No.1, pp. 37-42, 2010, DOI:10.3970/icces.2010.014.037

Abstract The applications of a finite element scheme to one-dimensional linear advection-diffusion equation, the incompressible Navier-Stokes equations, and compressible Euler system of equations are presented. The mesh-based scheme is the Petrov-Galerkin weak formulation with exponential weighting functions. Some numerical results demonstrate the workability and the validity of the present approach. More >

Chia-Cheng Tsai¹, Po-Ho Lin²

CMC-Computers, Materials & Continua, Vol.28, No.3, pp. 231-260, 2012, DOI:10.3970/cmc.2012.028.231

Abstract Recently, Liu (CMES 21(2007), 53) developed the modified collocation Trefftz method (MCTM) by setting a characteristic length slightly larger than the maximum radius of the computational domain. In this study, we find that the range of admissible characteristic length can be significantly enlarged if the LU decomposition is applied for solving the resulted dense unsymmetric matrix. Furthermore, we discover a range formula for admissible characteristic length, in which the number of the T-complete functions, the shape of the computation domain, and the exponent bits of the involved floating-point arithmetic have been taken into consideration. In order to validate the prescribed… More >