Mehrdad Ahmadi Kamarposhti^1,*, Hassan Shokouhandeh², Ilhami Colak³, Kei Eguchi⁴

CMC-Computers, Materials & Continua, Vol.73, No.2, pp. 4139-4156, 2022, DOI:10.32604/cmc.2022.029011

Abstract One method for eliminating oscillations in power systems is using stabilizers. By applying an appropriate control signal in the excitation system of a generator, a power system stabilizer improves the dynamic stability of power systems. However, the issue that is of high importance is the correct design of these stabilizers. These stabilizers must be designed to have proper performance when operating conditions change. When designed incorrectly, not only they do not improve the stability margin, but also increase the oscillations. In this paper, the robust design of power system stabilizers on a four-machine power system has been performed. For this… More >

M.L. Xie¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.14, No.3, pp. 85-90, 2010, DOI:10.3970/icces.2010.014.085

Abstract Various basis function based on Fourier-Chebyshev Petrov-Galerkin spectral method is described for computation of temporal linear stability in a circular jet. Basis functions presented here are exponentially mapped Chebyshev functions. There is a linear dependence between the components of the vector field according to the perturbation continuum equation. Therefore, there are only two degrees of freedom. According to the principle of permutation and combination, the basis function has three basic forms, i.e., the radial, azimuthal or axial component is free. The results show that three eigenvalues for various cases are consistent, but the basis function in case I is preferable… More >

Xie Ming-Liang¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.14, No.2, pp. 57-62, 2010, DOI:10.3970/icces.2010.014.057

Abstract Various basis function based on Fourier-Chebyshev Petrov-Galerkin spectral method is described for computation of temporal linear stability in a circular jet. Basis functions presented here are exponentially mapped Chebyshev functions. There is a linear dependence between the components of the vector field according to the perturbation continuum equation. Therefore, there are only two degrees of freedom. According to the principle of permutation and combination, the basis function has three basic forms, i.e., the radial, azimuthal or axial component is free. The results show that three eigenvalues for various cases are consistent, but the basis function in case I is preferable… More >

Xie Ming-Liang^1,2, Chan Tat-Leung², Yao Fu-Yuan³

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.1, pp. 39-54, 2010, DOI:10.3970/cmes.2010.067.039

Abstract A Fourier-Chebyshev Petrov-Galerkin spectral method is described for computation of temporal linear stability in a circular jet. The outer boundary of unbounded domains is truncated by large enough diameter. The mathematical formulation is presented in detail focusing on the analyticity of solenoidal vector field used for the approximation of the flow. The scheme provides spectral accuracy in the present cases studied and the numerical results are in agreement with former works. More >

Xie Ming-Liang^1,2, Zhou Huai-Chun¹, Chan Tat-Leung³

CMES-Computer Modeling in Engineering & Sciences, Vol.46, No.3, pp. 271-290, 2009, DOI:10.3970/cmes.2009.046.271

Abstract A Fourier-Chebyshev Petrov-Galerkin spectral method is described for computation of temporal linear stability in a circular jet. Basis functions presented here are exponentially mapped Chebyshev functions. They satisfy the pole condition exactly at the origin, and can be used to expand vector functions efficiently by using the solenoidal condition. The mathematical formulation is presented in detail focusing on the analyticity of solenoidal vector field used for the approximation of the flow. The scheme provides spectral accuracy in the present cases studied and the numerical results are in agreement with former works. More >

S. Rugonyi, K. J. Bathe¹

CMES-Computer Modeling in Engineering & Sciences, Vol.2, No.2, pp. 195-212, 2001, DOI:10.3970/cmes.2001.002.195

Abstract The solution of fluid flows, modeled using the Navier-Stokes or Euler equations, fully coupled with structures/solids is considered. Simultaneous and partitioned solution procedures, used in the solution of the coupled equations, are briefly discussed, and advantages and disadvantages of their use are mentioned. In addition, a simplified stability analysis of the interface equations is presented, and unconditional stability for certain choices of time integration schemes is shown. Furthermore, the long-term dynamic stability of fluid-structure interaction systems is assessed by the use of Lyapunov characteristic exponents, which allow differentiating between a chaotic and a regular system behavior. Some state-of-the-art numerical solutions… More >

A.Yu. Gelfgat¹, A. Rubinov², P.Z. Bar-Yoseph², A. Solan²

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.1, pp. 21-32, 2005, DOI:10.3970/fdmp.2005.001.021

Abstract The three-dimensional instability of the thermocapillary convection in cylindrical undeformable floating zones heated laterally is studied numerically. Different types of the boundary conditions, including radiation heating, linearized radiation and prescribed heat flux are used in the calculation. Stability diagrams showing the Prandtl number dependence of the critical Marangoni numbers that represent the thermocapillary forcing for different heating conditions are reported. It is shown that the primary instability of initially axisymmetric thermocapillary flows is defined mainly by the total amount of heat supplied through the heated side surface. The way in which the heat is supplied has a less significant effect… More >