This user page will be mainly used for my application to the U.S. universities. English is used instead 
of Chinese. Besides my basic informations, I will put some projects that I have done for the purpose of 
showing my adequate ability for a phd program.

Room 2011, No. 2 Building,
Lane 210, Zhengsu Road, Yangpu District,
Shanghai, China
Telephone: +86-21-65647946
Mobile Phone: 13917262947
Email: 06300300089@fudan.edu.cn
CV: Curriculum Vitae

2006-2010 Fudan University
Candidate for B.S. Material Science

Born in Liaoning Province, China, Xu Guoqiang is currently a senior at Fudan University. He has performed research on transparent conductive materials with Professor Zhang Qun's Group at Fudan University, measured the mobility of positrons in semiconductors with Professor C.D.Beling's positron laboratory at HKU and simulated the fractal growth of electrodeposition with Professor Sun Qi Outside of academics, Xu Guoqiang teaches Mandarin Chinese for secondary school students at King's College and performs physics experiments for primary school students in Shandong, China. He also enjoys playing volleyball with his friends. He is applying to universities in the U.S.A to pursue higher education in the field of computational material science and engineering. He is funded by the National Innovative Experiment Program for Undergraduates and has been offered the National Scholarship, Fung's Scholarship and the Sumsung Scholarship during his education at Fudan University.

• First-principles prediction based on density functional theory
• Finite Element Method and Finite Difference Method for solving engineering problems
• Inverse Problems and regularization methods for ill-posed problems

When the region of interest is unbounded, traditional numerical methods meet with difficulties. The solution of this problem is to add perfect matched layers(PML). Green function method is an alternative way to deal with boundless domains. I used this method to research the acoustic scattering on a kite-like boundary. I transformed the general solution of this problem into integral equation and then numerically solve this Fredholm equation of the second kind. A trigonometric interpolation scheme is designed to cope with the hyper-singular integral core. I further summarized the scattering patterns in different wavelengths and verified the simulation results with some analytical work in electrodynamics.

Scattering Problem

Scattering Problem

Inverse problems are to find the reasons behind the results and usually difficult to work out than forward problems. Regularization method is a powerful mathematic tool to solve inverse problems. Based on the Tichonov method, I studied how to use the scattering waves to reconstruct the irregular scattering boundary. Meanwhile, I adopted generalized cross-validation method for choosing regularization parameter. Simulation results showed that only incident waves with short wavelengths can be used to rebuild the boundary. I explained this phenomenon through calculating and observing the scattering patterns of different wavelengths. With this work, I complete the graduate-level summer school with excellent performance.

Inverse Scattering Problem

Finite difference method are widely used to solve differential equations from scattering or diffusion-reaction problems. With this method, I simulated the one dimensional glow discharge plasma. I used five magnetohydrodynamic equations to model this physical process. Due to strong coupling of these partial differential equations, I designed a stable numerical scheme to overcome this problem. My simulation results showed that electron temperatures in glow discharge plasma remained the same under different external voltages. This was in good agreement with my experimental measurements. I was honored to give a presentation in the 104th anniversary report of Fudan University with this work.

Plasma

Plasma

Finite element method has advantages over finite difference method when the region of interest has irregular boundaries or is in high dimensions. With this method, I calculated the two dimensional electric potential in an ion chamber, the boundary of which is not regular. I divided the domain into around 1000 triangles and used P1 conforming elements for interpolating. After mapping each of the scalene triangle domains to isosceles right ones, I performed Gaussian integration over these transformed regions.My simulation results revealed how accelerating voltage influences the focusing performance, which is of significance in obtaining a high resolution mass spectrum.

FEM

Using Monte Carlo method we can work out the statistical average of quantities in phase spaces or simulate growth of crystals under various conditions. Based on this method, I worked with Xiaomu Lin, Shuangping Liu and Yutian Sun to study the growth of copper that were far from equilibrium. Since this growth process is not in equilibrium and consequently the growth interfaces are extremely complex, analytical methods or traditional molecule dynamics method is not applicable. We adopted the diffusion limited aggregation(DLA) model and modified it by taking into considerations of the external electric and magnetic fields. Our simulation results resemble that of experiments as are shown in Figures. We further summarized the growth patterns under different concentrations of solution and electric fields. This work was awarded as the excellent National Innovative Experiment for Undergraduate.

Fractal Growth

Fractal Growth

I am so glad to see that you have up-dated this page. Could you please send me you current email address? By the way, the link to the new image does not work. — 乐永康 2012/01/03 21:20