About the Authors

Shaojian Qu

qushaojian@163.com

Affiliation Business School, University of Shanghai for Science and Technology, Shanghai, P.R. China

Ying Ji

¤ Current address: Room 721, Business School, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093, P.R. China

Affiliations Business School, University of Shanghai for Science and Technology, Shanghai, P.R. China, The Logistics Institute-Asia Pacific, National University of Singapore, Singapore, Singapore

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: SJQ. Performed the experiments: YJ. Analyzed the data: SJQ YJ. Contributed reagents/materials/analysis tools: YJ. Wrote the paper: SJQ YJ. The proof of theorems: SJQ.