Event(s) on December 2010

• 10/12/2010

  題目:	Generalized Linear Discriminant Analysis For Undersampled Problems
  講員:	Prof. Delin CHU, Department of Mathematics, National University of Singapore, Singapore
  時間/地點:	11:30  -  12:30 FSC1217, Fong Shu Chuen Library, HSH Campus, Hong Kong Baptist University
  摘要:	Dimensionality reduction has become an ubiquitous preprocessing step in many applications. Linear discriminant analysis (LDA) has been known to be one of the most optimal dimensionality reduction methods for classification. However, a main disadvantage of LDA is that the so-called "total scatter matrix" must be nonsingular. But, in many applications, the scatter matrices can be singular since the data points are from a very high-dimensional space and thus usually the number of the data samples is smaller than the data dimension. This is known as the undersampled problem. Many generalized LDA methods have been proposed in the past to overcome this singularity problem. There is a commonality for these generalized LDA methods, that is, they compute the optimal linear transformations by computing some eigen-decompositions and involving some matrix inversions. However, the eigen-decomposition is computationally expensive, and the involvement of matrix inverses may lead to that the methods are not numerically stable if the associated matrices are ill-conditioned. Hence, many existing LDA methods have high computational cost and potentially numerical instability problems. In this talk we introduce a new orthogonal LDA method for the undersampled problem. The main features of the introduced orthogonal LDA method include: (i) the optimal transformation matrix is obtained easily by only orthogonal transformations without computing any eigen-decomposition and matrix inverse, and consequently, the new method is inverse-free and numerically stable; (ii) the new method is implemented by using several QR factorizations and is a fast one. The effectiveness of the new method is illustrated by some real-world data sets.

  
  

• 14/12/2010

  題目:	Nonregular Designs: A Better Choice for Experiments
  講員:	Dr. Frederick Kin Hing PHOA, Institute of Statistical Science, Academia Sinica, Taiwan
  時間/地點:	11:30  -  12:30 FSC1217, Fong Shu Chuen Library, HSH Campus, Hong Kong Baptist University
  摘要:	In the recent past, there was a realization that nonregular designs could be utilized in conducting efficient experiments with flexibility, run size economy, and ability to exploit interactions. The first part of this talk discusses about the advantages on using nonregular designs over regular designs when an experiment is conducted. Several real-life examples are given for reference. These explicit advantages led to a growing research on developing a general construction methodology of nonregular designs with good properties. Recent research indicates that designs constructed from quaternary codes (QC) are very promising. The second part of this talk introduces the construction of nonregular designs via quaternary codes. The properties of QC designs are formulated and optimized using some formulas, bypassing the tedious calculation of J-characteristics. In the last part of this talk, several tables compare the design properties between QC designs and the best regular designs in the literature. The comparisons show that QC designs have better design properties and therefore, QC designs are more cost-efficient than regular designs of the same size.

  
  

• 17/12/2010

  題目:	Variational methods and their application on image processing
  講員:	Dr. MAO Yu, Institute for Mathematics and Its Applications, University of Minnesota, USA
  時間/地點:	11:30  -  12:30 FSC1217, Fong Shu Chuen Library, HSH Campus, Hong Kong Baptist University
  摘要:	Variational PDE based methods in digital image processing have been well developed and studied for the past twenty years. These methods were soon applied to image reconstruction problems. In this talk I will explore some interesting applications of these methods as well as the challenges in this field.

  
  

• 20/12/2010

  題目:	GPU Based Fluid Simulations
  講員:	Mr. ZHANG Yubo, Department of Computer Science, University of California, Davis , USA
  時間/地點:	16:30  -  17:30 FSC1217, Fong Shu Chuen Library, HSH Campus, Hong Kong Baptist University
  摘要:	In this talk, I will introduce the basic architecture and thead models of modern GPUs. An example of GPU-based fluid simulation will be presented. Some optimization techniques for GPU-based finite difference computation will also be dicussed.

  
  

• 21/12/2010

  題目:	Local absorbing boundary conditions for two-dimensional nonlinear wave equation
  講員:	Mr. LI Hongwei, Department of Mathematics, Hong Kong Baptist University, Hong Kong SAR
  時間/地點:	15:30  -  16:30 FSC1217, Fong Shu Chuen Library, HSH Campus, Hong Kong Baptist University
  摘要:	In this talk, we consider the numerical solution of two-dimensional nonlinear wave equation on unbounded spatial domain. One of the difficulties is how to reduce the unbounded spatial problem to a bounded one. Using the idea of operator splitting method, here we construct the efficient local absorbing boundary conditions for the nonlinear wave equation on artificial boundary. Several numerical examples are provided to demonstrate the effectiveness of our method.