Tuanjie Li^1,*, Yan Zhang¹, Jiaxing Zhou¹

CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.3, pp. 583-598, 2019, DOI:10.31614/cmes.2018.04891

Abstract In order to satisfy the high efficiency and high precision of collaborative robots, this work presents a novel trajectory planning method. First, in Cartesian space, a novel velocity look-ahead control algorithm and a cubic polynomial are combined to construct the end-effector trajectory of robots. Then, the joint trajectories can be obtained through the inverse kinematics. In order to improve the smoothness and stability in joint space, the joint trajectories are further adjusted based on the velocity look-ahead control algorithm and quintic B-spline. Finally, the proposed trajectory planning method is tested on a 4-DOF serial collaborative robot. The experimental results indicate… More >

Mizuma Takehito^1,*, Takei Amane¹

CMES-Computer Modeling in Engineering & Sciences, Vol.116, No.3, pp. 349-363, 2018, DOI: 10.31614/cmes.2018.01714

Abstract A matrix equation solved in an eddy current analysis, A-ϕ method based on a domain decomposition method becomes a complex symmetric system. In general, iterative method is used as the solver. Convergence of iterative method in an interface problem is improved by increasing an accuracy of a solution of an iterative method of a subdomain problem. However, it is difficult to improve the convergence by using a small convergence criterion in the subdomain problem. Therefore, authors propose a method to introduce double-double precision into the interface problem and the subdomain problem. This proposed method improves the convergence of the interface… More >

Chia-Cheng Tsai^1,2, D. L. Young³

CMES-Computer Modeling in Engineering & Sciences, Vol.94, No.2, pp. 175-205, 2013, DOI:10.3970/cmes.2013.094.175

Abstract It is well known that the method of fundamental solutions (MFS) is a numerical method of exponential convergence. In this study, the exponential convergence of the MFS is demonstrated by obtaining the eigensolutions of the Helmholtz equation. In the solution procedure, the sought solution is approximated by a superposition of the Helmholtz fundamental solutions and a system matrix is resulted after imposing the boundary condition. A golden section determinant search method is applied to the matrix for finding exponentially convergent eigenfrequencies. In addition, the least-squares method of fundamental solutions is applied for solving the corresponding eigenfunctions. In the solution procedure,… More >

D. Kourounis¹, L.N. Gergidis¹, A. Charalambopoulos¹

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.3, pp. 185-202, 2008, DOI:10.3970/cmes.2008.028.185

Abstract The sensitivity of analytical solutions of the direct acoustic scattering problem in prolate spheroidal geometry on the wavenumber and shape, is extensively investigated in this work. Using the well known Vekua transformation and the complete set of radiating "outwards'' eigensolutions of the Helmholtz equation, introduced in our previous work ([Charalambopoulos and Dassios(2002)], [Gergidis, Kourounis, Mavratzas, and Charalambopoulos (2007)]), the scattered field is expanded in terms of it, detouring so the standard spheroidal wave functions along with their inherent numerical deficiencies. An approach is employed for the determination of the expansion coefficients, which is optimal in the sense, that minimizes the… More >

L.N. Gergidis, D. Kourounis, S. Mavratzas, A. Charalambopoulos¹

CMES-Computer Modeling in Engineering & Sciences, Vol.21, No.2, pp. 157-176, 2007, DOI:10.3970/cmes.2007.021.157

Abstract A new complete set of scattering eigensolutions of Helmholtz equation in spheroidal geometry is constructed in this paper. It is based on the extension to exterior boundary value problems of the well known Vekua transformation pair, which connects the kernels of Laplace and Helmholtz operators. The derivation of this set is purely analytic. It avoids the implication of the spheroidal wave functions along with their accompanying numerical deficiencies. Using this novel set of eigensolutions, we solve the acoustic scattering problem from a soft acoustic spheroidal scatterer, by expanding the scattered field in terms of it. Two approaches concerning the determination… More >

V. Gowrishankar^1,*, K. Venkatachalam¹

CMC-Computers, Materials & Continua, Vol.60, No.3, pp. 947-957, 2019, DOI:10.32604/cmc.2019.07749

Abstract A high precision 10-bit successive approximation register analog to digital converter (ADC) designed and implemented in 32nm CNTFET process technology at the supply of 0.6V, with 73.24 dB SNDR at a sampling rate of 640 MS/s with the average power consumption of 120.2 μW for the Internet of things node. The key components in CNTFET SAR ADCs are binary scaled charge redistribution digital to analog converter using MOS capacitors, CNTFET based dynamic latch comparator and simple SAR digital code error correction logic. These techniques are used to increase the sampling rate and precision while ensuring the linearity, power consumption and… More >