Jinping Zhang^1,2, Youlai Jin¹, Bin Sun^1,*, Yuping Han³, Yang Hong⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.2, pp. 755-770, 2021, DOI:10.32604/cmes.2021.012686

Abstract The complex nonlinear and non-stationary features exhibited in hydrologic sequences make hydrological analysis and forecasting difficult. Currently, some hydrologists employ the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) method, a new time-frequency analysis method based on the empirical mode decomposition (EMD) algorithm, to decompose non-stationary raw data in order to obtain relatively stationary components for further study. However, the endpoint effect in CEEMDAN is often neglected, which can lead to decomposition errors that reduce the accuracy of the research results. In this study, we processed an original runoff sequence using the radial basis function neural network (RBFNN) technique… More >

Liqun Wang¹, Zengtao Chen², Guolai Yang^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.2, pp. 479-503, 2021, DOI:10.32604/cmes.2021.011954

Abstract This paper proposes a non-intrusive uncertainty analysis method for artillery dynamics involving hybrid uncertainty using polynomial chaos expansion (PCE). The uncertainty parameters with sufficient information are regarded as stochastic variables, whereas the interval variables are used to treat the uncertainty parameters with limited stochastic knowledge. In this method, the PCE model is constructed through the Galerkin projection method, in which the sparse grid strategy is used to generate the integral points and the corresponding integral weights. Through the sampling in PCE, the original dynamic systems with hybrid stochastic and interval parameters can be transformed into deterministic dynamic systems, without changing… More >

Chao Ma, Yunkai Gao^*, Yuexing Duan, Zhe Liu

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.2, pp. 715-738, 2021, DOI:10.32604/cmes.2021.011187

Abstract Stress-based topology optimization is one of the most concerns of structural optimization and receives much attention in a wide range of engineering designs. To solve the inherent issues of stress-based topology optimization, many schemes are added to the conventional bi-directional evolutionary structural optimization (BESO) method in the previous studies. However, these schemes degrade the generality of BESO and increase the computational cost. This study proposes an improved topology optimization method for the continuum structures considering stress minimization in the framework of the conventional BESO method. A global stress measure constructed by p-norm function is treated as the objective function. To… More >

Yi Ji^1,2, Yufeng Xing^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.2, pp. 549-575, 2021, DOI:10.32604/cmes.2021.014244

Abstract Based on the weighted residual method, a single-step time integration algorithm with higher-order accuracy and unconditional stability has been proposed, which is superior to the second-order accurate algorithms in tracking long-term dynamics. For improving such a higher-order accurate algorithm, this paper proposes a two sub-step higher-order algorithm with unconditional stability and controllable dissipation. In the proposed algorithm, a time step interval [tk, tk + h] where h stands for the size of a time step is divided into two sub-steps [tk, tk + γh] and [tk + γh, tk + h]. A non-dissipative fourth-order algorithm is used in the rst… More >

Hongwei Zhang^1,2, Zhijun Wan³, Yixin Zhao^1,2, Yuan Zhang³, Yulong Chen^2,*, Junhui Wang^3,*, Jingyi Cheng³

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.2, pp. 443-455, 2021, DOI:10.32604/cmes.2021.013179

Abstract In the enhanced geothermal system (EGS), the injected fluid will induce shear sliding of rock fractures (i.e., hydroshearing), which consequently, would increase the fracture aperture and improve the heat transfer efficiency of the geothermal reservoir. In this study, theoretical analysis, experimental research and numerical simulation were performed to uncover the permeability and heat transfer enhancement mechanism of the Hot-Dry-Rock (HDR) mass under the impact of shearing. By conducting the direct shear test with the fractured rock samples, the evolution process of fracture aperture during the shearing tests was observed, during which process, cubic law was adopted to depict the rock… More >

T. K. Sreelakshmi¹, Abraham Annamma¹, A. S. Chethan¹, M. Krishna Murthy², C. S. K. Raju^3,*

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.2, pp. 599-616, 2021, DOI:10.32604/cmes.2021.013077

Abstract The current article discusses the heat transfer characteristics of ferromagnetic liquid over an elastic surface with the thermal radiation and non-Fourier heat flux. In most of the existing studies, the heat flux is considered as constant, but whereas we incorporated the non-Fourier flux to get the exact performance of the flow. Also, we excluded the PWT and PHF cases to control the boundary layer of the flow. The governing equations related to our contemplate are changed into non-linear ordinary differential equations (ODE’s) by utilizing appropriate similarity changes, which are at the point enlightened by Runge–Kutta based shooting approach. The equations… More >

Thabet Abdeljawad^1,2,3, Muhammad Bilal Riaz^4,5, Syed Tauseef Saeed^6,*, Nazish Iftikhar⁶

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.2, pp. 821-841, 2021, DOI:10.32604/cmes.2021.012529

Abstract The main focus of this study is to investigate the impact of heat generation/absorption with ramp velocity and ramp temperature on magnetohydrodynamic (MHD) time-dependent Maxwell fluid over an unbounded plate embedded in a permeable medium. Non-dimensional parameters along with Laplace transformation and inversion algorithms are used to find the solution of shear stress, energy, and velocity profile. Recently, new fractional differential operators are used to define ramped temperature and ramped velocity. The obtained analytical solutions are plotted for different values of emerging parameters. Fractional time derivatives are used to analyze the impact of fractional parameters (memory effect) on the dynamics… More >

Ramadan A. ZeinEldin^1,2, Christophe Chesneau^3,*, Farrukh Jamal⁴, Mohammed Elgarhy⁵, Abdullah M. Almarashi⁶, Sanaa Al-Marzouki⁶

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.2, pp. 791-819, 2021, DOI:10.32604/cmes.2021.012169

Abstract Understanding a phenomenon from observed data requires contextual and efficient statistical models. Such models are based on probability distributions having sufficiently flexible statistical properties to adapt to a maximum of situations. Modern examples include the distributions of the truncated Fréchet generated family. In this paper, we go even further by introducing a more general family, based on a truncated version of the generalized Fréchet distribution. This generalization involves a new shape parameter modulating to the extreme some central and dispersion parameters, as well as the skewness and weight of the tails. We also investigate the main functions of the new… More >

Weidong Lei¹, Hai Zhou^1,*, Hongjun Li², Rui Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.2, pp. 577-597, 2021, DOI:10.32604/cmes.2021.011857

Abstract In order to simulate the propagation process of subway vibration of parallel tunnels in semi-infinite rocks or soils, time domain boundary element method (TD-BEM) formulation for analyzing the dynamic response of twin-parallel circular tunnels in an elastic semi-infinite medium is developed in this paper. The time domain boundary integral equations of displacement and stress for the elastodynamic problem are presented based on Betti’s reciprocal work theorem, ignoring contributions from initial conditions and body forces. In the process of establishing time domain boundary integral equations, some virtual boundaries are constructed between finite boundaries and the free boundary to form a boundary… More >

Mohamed Abd-Elbasseer^*, Hatem Kh Mohamed

Sound & Vibration, Vol.55, No.1, pp. 43-55, 2021, DOI:10.32604/sv.2021.09417

Abstract This research presents a thorough evaluation of the reverberation room at Acoustics Laboratory in National Institute of Standards (NIS) according to the related international standards. The evaluation aims at examining the room performance and exploring its effectiveness in the frequency range from 125 Hz to 10000 Hz according to the international standard requirements. The room, which was designed and built several years ago, is an irregular rectangular shape free from diffusers. Its volume is about 158.84 m³, which meets the requirement of the ISO 354 standard L_max < 1.9V^1/3. Cut-off frequencies of one and one-third octave are 63 Hz and… More >