A parallel finite element algorithm for simulation of the generalized Stokes problem

Yueqiang Shang 대한수학회 2016 대한수학회보 Vol.53 No.3

Based on a particular overlapping domain decomposition \linebreak technique, a parallel finite element discretization algorithm for the generalized Stokes equations is proposed and investigated. In this algorithm, each processor computes a local approximate solution in its own subdomain by solving a global problem on a mesh that is fine around its own subdomain and coarse elsewhere, and hence avoids communication with other processors in the process of computations. This algorithm has low communication complexity. It only requires the application of an existing sequential solver on the global meshes associated with each subdomain, and hence can reuse existing sequential software. Numerical results are given to demonstrate the effectiveness of the parallel algorithm.

On the linearization of defect-correction method for the steady Navier-Stokes equations

Yueqiang Shang,김도완,조태창 대한수학회 2013 대한수학회지 Vol.50 No.5

Based on finite element discretization, two linearization approaches to the defect-correction method for the steady incompressible Navier-Stokes equations are discussed and investigated. By applying m times of Newton and Picard iterations to solve an artificial viscosity stabilized nonlinear Navier-Stokes problem, respectively, and then correcting the solution by solving a linear problem, two linearized defect-correction algorithms are proposed and analyzed. Error estimates with respect to the mesh size h, the kinematic viscosity v, the stability factor α and the number of nonlinear iterations m for the discrete solution are derived for the linearized one-step defect-correction algorithms. Efficient stopping criteria for the nonlinear iterations are derived. The influence of the linearizations on the accuracy of the approximate solutions are also investigated. Finally, numerical experiments on a problem with known analytical solution, the lid-driven cavity flow, and the flow over a backward-facing step are performed to verify the theoretical results and demonstrate the effectiveness of the proposed defect-correction algorithms.

A PARALLEL FINITE ELEMENT ALGORITHM FOR SIMULATION OF THE GENERALIZED STOKES PROBLEM

Shang, Yueqiang Korean Mathematical Society 2016 대한수학회보 Vol.53 No.3

Based on a particular overlapping domain decomposition technique, a parallel finite element discretization algorithm for the generalized Stokes equations is proposed and investigated. In this algorithm, each processor computes a local approximate solution in its own subdomain by solving a global problem on a mesh that is fine around its own subdomain and coarse elsewhere, and hence avoids communication with other processors in the process of computations. This algorithm has low communication complexity. It only requires the application of an existing sequential solver on the global meshes associated with each subdomain, and hence can reuse existing sequential software. Numerical results are given to demonstrate the effectiveness of the parallel algorithm.

ON THE LINEARIZATION OF DEFECT-CORRECTION METHOD FOR THE STEADY NAVIER-STOKES EQUATIONS

Shang, Yueqiang,Kim, Do Wan,Jo, Tae-Chang Korean Mathematical Society 2013 대한수학회지 Vol.50 No.5

Based on finite element discretization, two linearization approaches to the defect-correction method for the steady incompressible Navier-Stokes equations are discussed and investigated. By applying $m$ times of Newton and Picard iterations to solve an artificial viscosity stabilized nonlinear Navier-Stokes problem, respectively, and then correcting the solution by solving a linear problem, two linearized defect-correction algorithms are proposed and analyzed. Error estimates with respect to the mesh size $h$, the kinematic viscosity ${\nu}$, the stability factor ${\alpha}$ and the number of nonlinear iterations $m$ for the discrete solution are derived for the linearized one-step defect-correction algorithms. Efficient stopping criteria for the nonlinear iterations are derived. The influence of the linearizations on the accuracy of the approximate solutions are also investigated. Finally, numerical experiments on a problem with known analytical solution, the lid-driven cavity flow, and the flow over a backward-facing step are performed to verify the theoretical results and demonstrate the effectiveness of the proposed defect-correction algorithms.

PTEN/Akt Signaling-Mediated Activation of the Mitochondrial Pathway Contributes to the 3,3'-Diindolylmethane-Mediated Antitumor Effect in Malignant Melanoma Cells

Xiaoli Wang,Yueqiang Zhao,Mosheng Yu,Yu Xu 한국식품영양과학회 2020 Journal of medicinal food Vol.23 No.12

3,3′-diindolylmethane (DIM) has an anticancer activity, but the role DIM plays on malignant melanoma cells and its specific mechanism is unclear. We studied the biological effects of DIM on malignant melanoma cells and the related mechanism and the results showed that DIM significantly suppressed cell proliferation and induced apoptosis in malignant melanoma cells. In addition, the expression levels of phosphatase and tensin homolog deleted on chromosome ten (PTEN), Bax, Bid, cleaved caspase-3, and cleaved caspase-9 were increased after DIM treatment. In A2058 PTENmut cells, DIM-mediated inhibition of proliferation and DIM-induced apoptosis were attenuated. Additionally, the overexpression and knockdown of PTEN could regulate such effects of DIM in malignant melanoma cells. Furthermore, DIM exerted growth-inhibiting and apoptosis-inducing effects in vivo. This study demonstrated that DIM has antitumor effect in human malignant melanoma cells through the mitochondrial apoptotic pathway activated by PTEN/Akt signaling.

Vertical Handoff Decision Algorithm combined Improved Entropy Weighting with GRA for Heterogeneous Wireless Networks

( Shasha Zhao ),( Fei Wang ),( Yueqiang Ning ),( Yi Xiao ),( Dengying Zhang ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.11

Future network scenario will be a heterogeneous wireless network environment composed of multiple networks and multimode terminals (MMT). Seamless switching and optimal connectivity for MMT among different networks and different services become extremely important. Here, a vertical handoff algorithm combined an improved entropy weighting method based on grey relational analysis (GRA) is proposed. In which, the improved entropy weight method is used to obtain the objective weights of the network attributes, and GRA is done to rank the candidate networks in order to choose the best network. Through simulation and comparing the results with other vertical handoff decision algorithms, the number of handoffs and reversal phenomenon are reduced with the proposed algorithm, which shows a better performance.

Dissimilatory Azoreduction of Orange I by a Newly Isolated Moderately Thermophilic Bacterium, Novibacillus thermophilus SG-1

Zhen Yu,Xuemei Zhou,Yueqiang Wang,Guiqin Yang,Shungui Zhou 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.6

Dye wastewater normally is discharged at high temperature, but thermophilic bacteria capable of decolorizing azo dyes have rarely been isolated. Here we report a newly isolated moderately thermophilic bacterium, Novibacillus thermophilus SG-1, which had a remarkable ability to decolorize the azo dye Orange I by utilizing a large variety of organic substrates as electron donors. When Orange I served as the sole electron acceptor, almost complete decolorization occurred at 50ºC and pH 8.0 with acetate as the electron donor after anaerobic incubation of strain SG-1 for 24 h. The decolorization process followed the pseudofirst- order kinetics. The complete reduction of 0.3 mM Orange I was accompanied by a stoichiometric consumption of 0.17 mM acetate over time. The measured molar ratio (1.76) of Orange I reduced to acetate oxidized was close to the theory value of 2.0, suggesting that most of the electrons released by acetate had been transported to Orange I. Simultaneously energy generated from the electron transfer process was used to support cell anaerobic growth, which meant that azoreduction by strain SG-1 is an azorespiration process. To our knowledge, this is the first report of a thermophilic bacterium capable of azorespiration, which increases the limited number of bacteria for treating hightemperature azo dye wastewater.