H Welcome

Hi, I am Xi. I graduated from National University of Singapore with Double Degree of Applied Mathematics and Computer Science.

Now, I am a fifth year computer science PhD student at Duke University. My research interests are broadly in database and data analysis. I am currently exploring privacy-related projects with Prof. Ashwin Machanavajjhala.

Download my CV here (updated by Aug 2017)

News: I was awarded a 2017 Google PhD Fellowship in Privacy and Security.  



Contact Information
Duke University
Dept. of Computer Science
LSRC Building D101
308 Research Drive, Campus Box 90129
Durham, NC 27708
P: (919) 660-4007


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Blowfish Privacy: Tuning Privacy-Utility Trade-offs using Policies

Collaborators: Ashwin Machanavajjhala and Bolin Ding · This research aims to provide ways for trading-off the privacy of individuals in a statistical database for the utility of downstream analysis of data. We present a novel class of privacy definitions - Blowfish privacy, which offers a rich interface to specify this trade-off. We show significant utility improvements for k-means clustering, releasing cumulative histograms and answering range queries with mechanisms under Blowfish privacy in comparison to their differentially private counterparts. (more details)

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Differentially Private Trajectory Synthesis

Collaborators: Ashwin Machanavajjhala, Divesh Srivastava, Cecilia M. Procopiuc, Graham Cormode · This research considers methods to publish locations traces with differential privacy guarantee. Our approach involves modeling the location traces as top-k mobility patterns for a bounded sensitivity, and sampling location traces from a noisy semi-Markov model learned on the top-k patterns. We present pruning strategies and efficient algorithms to post-process the noisy model which has an unbalanced hierarchical structure and to synthesize locations traces closer to the real datasets.(more details)

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Coloring Privacy

This project has studied privacy in mobile-social system from another angle, visualization. Visualization creates images, graphics or animations to enhance people's understanding of information....(more details)

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GPU Computing

Driven by the high computation power and affordability of Graphics Processing Units, known as GPU, we would like to explore the new role of GPU as a more general purpose processor for scientific and engineering applications.... (more details)




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Ashwin Machanavajjhala, Xi He, Michael Hay, "Differential privacy in the wild: a tutorial on current practices
& open challenges", SIGMOD 2017 link

Xi He, Ashwin Machanavajjhala, Cheryl Flynn, Divesh Srivastava, "Composing differential privacy and secure
computation: A case study on scaling private record linkage”, accepted in CCS 2017

Xi He, Nisarg Raval, Ashwin Machanavajjhala, "A Demonstration of VisDPT: visual exploration of differentially
private trajectories", VLDB 2016 (BEST DEMO AWARD) pdf

Ashwin Machanavajjhala, Xi He, Michael Hay, "Differential privacy in the wild: a tutorial on current practices
& open challenges", VLDB 2016 link

Xi He, Graham Cormode, Ashwin Machanavajjhala, Cecilia M. Procopiuc, Divesh Srivastava, “DPT: Differentially
private trajectory synthesis using hierarchical reference systems”, VLDB 2015 pdf code

Xi He, Ashwin Machanavajjhala, Bolin Ding, “Blowfish Privacy: Tuning Privacy-Utility Trade-offs using Policies”,
SIGMOD 2014 pdf

Y.C. Tay, Xuanran Zong, Xi He, “An Equation-Based Heap Sizing Rule”,
Performance Evaluation 70, 11 (Nov. 2013), 948–964.



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I like dancing, martial arts, basketball, swimming, web designs, movies...