Welcome

to my homepage. I am a final year Ph.D. student at Princeton University advised by Prof. Peter Ramadge. I am a member of the Ramadge Research Group. I have a strong interest in machine learning: Our modern society is blessed with the ability to acquire massive amounts of data, but challenged by the difficulty of turning this data into useful information. My long-term goal is to provide a fundamental understanding of how this challenge can be met.

Research and Publications

My Ph.D. research builds on the concept of "sparse representation". I study how additional structure can be incorporated with sparsity to improve various signal/data representation, denoising and classification algorithms. This work falls into the following 3 areas:

1. Learning sparse dictionary representations efficiently.

Z. J. Xiang, P. J. Ramadge, "Fast lasso screening tests based on correlations", accepted, ICASSP 2012

Z. J. Xiang, H. Xu, P. J. Ramadge, "Learning sparse representations of high dimensional data on large scale dictionaries" (Supplemental material), NIPS 2011, nips.cc (Supplemental), BibTex, MATLAB Toolbox, Watch my presentation on videolectures.net

2. Connecting the structured sparsity of decision trees with wavelet coefficients and Besov space, for a coherent understanding of edge preservation in image denoising.

Z. J. Xiang, P. J. Ramadge, "Edge preserving image regularization based on morphological wavelets and dyadic trees", to appear, IEEE Transactions on Image Processing
Z. J. Xiang, Z. Zhang, P. Xu, P. J. Ramadge, "Learning a wavelet tree for multichannel image denoising", ICIP 2011, IEEE Xplore, BibTex, MATLAB Toolbox
Z. J. Xiang, P. J. Ramadge, "Morphological wavelet transform with adaptive dyadic structures" (Correction), ICIP 2010, IEEE Xplore, BibTex
Z. J. Xiang, P. J. Ramadge, "Morphological wavelets and the complexity of dyadic trees", ICASSP 2010, IEEE Xplore, BibTex

3. Improved boosting algorithms for sparse and structured fMRI voxel selection.

Z. J. Xiang, Y. T. Xi, U. Hasson, P. J. Ramadge, "Boosting with spatial regularization" (Supplemental material), NIPS 2009, nips.cc (Supplemental), BibTex
Z. J. Xiang, P. J. Ramadge, "Sparse boosting", ICASSP 2009, IEEE Xplore, BibTex
Y. T. Xi, Z. J. Xiang, P. J. Ramadge, R. Schapire, "Speed and sparsity of regularized boosting", AISTATS 2009, csail.mit.edu, BibTex

Education

	2009-Present	Ph.D. Candidate
	2007-2009	M.A.
	Electrical Engineering, Princeton University
	Advisor: Prof. Peter J. Ramadge

	2003-2007	B.E.
	Electrical Engineering, Tsinghua University
	With honors. GPA Rank: 1/164

Selected Academic Honors

Charlotte Elizabeth Procter Fellow	2011-2012
Honorific Fellowship, Princeton University

Francis Robin Upton Fellow	2007-2011
Princeton University

Outstanding Fellow (top 2%)	2003-2007
Awarded 4 years in a row, Tsinghua University

IMO Gold Medalist	2003
Tokyo, Japan. Worldwide Rank: 12/457