Research
Changhui Tan

Changhui Tan

I am a postdoctoral research associate in CSCAMM and Department of Mathematics, University of Maryland. 

 

  • This is a joint work with Qianyun Miao and Liutang Xue.
  • The preprint is available on arXiv:2004.03652.

 Speaker: Rihui Lan (University of Nevada, Las Vegas)

In this talk, two different moving interface problems are studied by different arbitrary Lagrangian-Eulerian (ALE) finite element methods. For the transient Stokes/parabolic coupling with jump coefficients—a linearized fluid-structure interaction (FSI) problem, a novel \(H^1\)-projection is defined to account for the mesh motion. The well-posedness and optimal convergence properties in both the energy norm and \(L^2\) norm are analyzed for this mixed-type \(H^1\)-projection, with which the stability and optimal error estimate in the energy norm are derived for both semi- and fully discrete mixed finite element approximations to the Stokes/parabolic interface problem. For the parabolic/mixed parabolic moving interface problem with jump coefficients, a stable Stokes-pair mixed FEM within a specific stabilization technique and a novel ALE time-difference scheme are developed to discretize this interface problem in both semi- and fully discrete fashion, for which the stability and optimal error estimate analyses are conducted.
 

Time: March 27, 2020 2:30pm-3:30pm
Location: LC317R
Host: Lili Ju

 Speaker: Hailiang Liu (Iowa State University)

We are concerned with positive and energy-dissipating schemes for solving the time-dependent system of Poisson-Nernst-Planck (PNP) equations, which has found much use in the modeling of biological membrane channels and semiconductor devices. As a gradient flow in density space, this strongly coupled system of nonlinear equations can take long time evolution to reach steady states. Hence, designing efficient and stable methods is highly desirable. In this talk we shall present a class of methods with structure-preserving properties for the PNP system, and review advances around related models such as the quantum diffusion equation.
 

Time: February 21, 2020 2:30pm-3:30pm
Location: LC317R
Host: Changhui Tan

 

  • This is a joint work with Yi Sun.
  • The preprint is available on arXiv:2001.10017.

 Speaker: Xiangcheng Zheng (University of South Carolina)

We proved the wellposedness of variable-order mobile-immobile time-fractional diffusion equations and the regularity of their solutions. Optimal-order finite element approximation was presented and analyzed. Numerical experiments were carried out for demonstration.
 

Time: January 31, 2020 2:30pm-3:30pm
Location: LC317R

Speaker: Xiaolin Li (Stony Brook University)

In this talk, I will review the history of the Lagrangian front tracking method and the computational platform built on this methodology. I will review the front tracking in the study of fluid interface instabilities, including Rayleigh-Taylor instability, Richtmyer Meshkov instability and fluid mixing induced by these instabilities. I will also introduce a fully conservative front tracking scheme and its application in the phase transition problem.
 

Time: March 20, 2020 2:30pm-3:30pm
Location: LC317R
Host: Xinfeng Liu

 Speaker: Yuanwei Qi (University of Central Florida)

In this talk, I shall report some recent progress on the existence and multiplicity of traveling waves to one of the most important models in Turing Pattern Formation. In addition, I shall pose some questions which are wide open which demand new ideas and fresh approaches. This is a joint-work with Xinfu Chen et al.
 

Time: January 17, 2020 2:30pm-3:30pm
Location: LC317R
Host: Changhui Tan

Monday, 23 September 2019 09:01

MacOS change keychain password

In the MacOS system, the keychain password has to match the user password in order to use keychain appropriately. In my case, they have to match in order to allow Apple Watch to unlock the Mac.

The official way to change the keychain password can be found HERE. However, in my case, the "Change password for keychain login" option is in gray and can not be selected. One solution is the following:

Open terminal and type in

security set-keychain-password

Then, type in old password and then new password. The password is then changed. This does not require admin access.

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