## Changhui Tan

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

### Change default mail app in OS X

Here is the steps to change default mail app in OS X:

- Open
**Mail**app. - Select Preferences -> General. Under "Default email reader", select your preferred mail app.

I am running into a problem by following the steps: the default email reader changes back to the original mail app seconds after I made the change. Here is the solution that works for me. Open terminal. Copy and paste the following script.

`/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -all local,system,user`

Then try step 1-2 again, and it won't change back again!

### Finite time blow up in the hyperbolic Boussinesq system

- This is a joint work with
*Alexander Kiselev*. - The paper has been published in
*Advances in Mathematics*doi:10.1016/j.aim.2017.11.019.

- The preprint is available on arXiv:1609.02468.

### Application of natural neighbor interpolation method in three-dimensional geological model

- This is a joint work with
*Yan-jun Guo, Mao Pan, Fei Yan, Zhe Wang and Tiao Lu*. - The paper has been published in
*Joumal of PLA University of Science and Technology(Natural Science Edition)*doi:10.3969/j.issn.1009-3443.2009.06.026.

### Hierarchical construction of bounded solutions to divU = F

- This is a joint work with
*Eitan Tadmor*. - It has been published in a chapter of the book
*Nonlinear Partial Differential Equations, Volume 7 of the series Abel Symposia*doi:10.1007/978-3-642-25361-4_14.

Here is an outline of the paper.

We propose a numerical approach to solve the minimization problem of the hierarchical decomposition introduced by Tadmor [Ta15], using duality to treat with \(L^{\infty}\) norm inside. And then generate the uniformly bounded solution of \(\nabla\cdot U = F\) in actual computation.

### First-order aggregation models with alignment

- This is a joint work with
*Razvan C. Fetecau*and*Weiran Sun*. - The paper has been published in
*Physica D: Nonlinear Phenomena*doi:10.1016/j.physd.2016.03.011.

- The preprint is available on arXiv:1505.07316.

### Gauss elimination

The purpose of this note is to clarify questions and statements in class, and a step-by-step way to find an LU decomposition by hand.

### Polynomial interpolation

The purpose of this note is to clarify questions and statements in class, and to provide detailed procedures to find polynomial interpolations.

### Carleson measure

This note is taken in the PDE discussion group in 2012, on the topic of important spaces in fluid dynamics.

Lecture 2: Carleson measure

### An introduction to BMO Space

This note is taken in the PDE discussion group in 2012, on the topic of important spaces in fluid dynamics.

Lecture 1: An introduction to BMO Space

### Ph.D. Defense

I have finished my Ph.D. defense today. My committees are Prof. Eitan Tadmor (Chair/Advisor), Prof. Pierre-Emmanuel Jabin, Prof. Dave Levermore, Prof. Antoine Mellet and Prof. Howard Elman (Dean's representative).

My thesis title is, **Multi-scale problems on collective dynamics and image processing**. The manuscript can be found doi:10.13016/M2WG6T.