
Computer Engineering Seminar
Mon, Feb 28, 2011 @ 11:00 AM  12:00 PM
Ming Hsieh Department of Electrical and Computer Engineering
Conferences, Lectures, & Seminars
Speaker: Weikang Qian, University of Minnesota
Talk Title: Digital yet Deliberately Random: Synthesizing Logical Computation on Stochastic Bit Streams
Abstract: Most digital circuits process information deterministically as zeros and ones. For example, the arithmetic unit of a modern computer performs calculations on deterministic integer or floatingpoint values represented in binary radix. However, digital computation need not be deterministic. In my research, I consider an alternative paradigm: digital circuits that compute on stochastic sequences of zeros and ones. Such circuits can implement complex arithmetic operations with very simple hardware. Also they are highly tolerant of soft errors (i.e., bit flips). In the first part of my talk, I will present a general method for synthesizing combinational circuits that compute on stochastic bit streams. The method can be used to synthesize arbitrary polynomial functions. Through polynomial approximations, it can also be used to synthesize nonpolynomial functions.
Schemes for probabilistic computation can exploit physical sources to generate random bit streams. Generally, each source has a fixed bias and so provides bits that have a specific probability of being one versus zero. If many different probability values are required, it can be difficult or expensive to generate all of these directly from physical sources. In the second half of my talk, I will describe techniques for synthesizing circuits that transform source probabilities into target probabilities, entirely through combinational logic. I will conclude my talk by discussing potential applications of the design methodology for emerging nanoscale technologies, such as nanowire crossbar arrays and carbon nanotubes.
Biography: Weikang Qian is a finalyear Ph.D. student in the Department of Electrical and Computer Engineering at the University of Minnesota. He received his Bachelor of Engineering degree in Automation from Tsinghua University, Beijing, China, in 2006. He has research interests in diverse fields such as computeraided design of integrated circuits, circuit design for emerging technologies, and faulttolerant computing. In recognition of his doctoral research, he received the Doctoral Dissertation Fellowship at the University of Minnesota. One of his papers was nominated for the William J. McCalla Best Paper Award at the 2009 International Conference on ComputerAided Design (ICCAD), a top conference in the field of electronic design automation.
Host: Sandeep Gupta
Location: Hughes Aircraft Electrical Engineering Center (EEB) 
Audiences: Everyone Is Invited
Contact: Estela Lopez