The George Nicholson Student Paper Competition, arguably the most prestigious student award in the operations research community, is held each year to honor outstanding student papers in the field of operations research and the management sciences.

Zhang received the Nicholson Award for his paper, “Refined Square-Root Staffing for Call Centers with Impatient Customers,” which he co-authored with Johan van Leeuwaarden and Bert Zwart, ISyE adjunct associate professor and Zhang’s thesis advisor.

In the paper, Zhang studied how to solve for the minimum staffing level subject to different service-level constraints for call centers with impatient customers. The authors developed an approximate solution procedure, which they named "refined square-root staffing,” and then demonstrated that this approach preserves the insightfulness and computational scalability of the celebrated square-root staffing principle and yet is provably more accurate.

About the paper, Zwart said that it is a “well-written, solid theoretical basis that provides relevant practical insights for the most popular model out there for call centers.”

Zhang wrote the paper while a guest at Bell Labs, but also worked with Sem Borst and Martin Reiman at Alcatel-Lucent and Josh Reed (PhD IE 2007) at NYU. Reed also received the Nicholson Award while a student at Georgia Tech.

In addition to the Nicholson Award, Zhang also received the Performance Best Student Paper award for his paper “Optimal Server Scheduling in Hybrid P2P Networks,” which he co-authored with Borst and Reiman.

In this paper, the authors studied how to manage server capacity in hybrid peer-to-peer networks, an increasingly popular type of Internet content distribution paradigm in which each user plays a dual client-server role. According to Zhang, “we find that the structure of optimal server scheduling policies in such systems depends intricately upon the altruism level of users (i.e., users' willingness to stay in the system and continue helping others after their download completion).

About this recent accomplishment, Zhang said that “a lot of credit should go to the four coauthors of the two papers, who are also great mentors, especially my thesis advisor, Bert Zwart.”

Zwart and Zhang’s co-advisor Hayriye Ayhan, ISyE professor, are proud of Zhang, noting that he is exceptional in that he has broad research interests and is able to work on diverse research projects simultaneously. In addition to his work with Zwart and Ayhan, Zhang has collaborated with top researchers in and out of the country, which, according to Ayhan, is very unusual for a PhD student. With Ayhan, Zhang has been developing optimal admission control policies in two-stage loss networks. “To the best of our knowledge,” states Ayhan, Zhang’s “work is the first one that completely characterizes the optimal admission policies in this setting.”

To read Zhang’s research papers, visit his webpage at http://www2.isye.gatech.edu/~bzhang34/.