(1) Generalized flow in complex system
If complex network is the skeleton of a complex system, the flow in the system, including energy flow and material flow, is the blood. Zhang focuses on the flow that can be abstracted into weighted directed network and studies its general laws, especially the allometric growth rate in flow system. His studies include energy flow and food web in ecosystem, commodity flow in international trade, click-stream on the Internet, input and output network in economic system, and highway traffic flow.
(2) Allometric growth rate
According to the well-known Kleiber's law, for the vast majority of animals, an animal’s metabolic rate scales to the 3/4 power of the animal’s mass. Further researches show that this law is generally applicable in many complex systems, including city, nation, and Internet. And this law is the embodiment of the complex network’ fractal growth. Zhang mainly focuses on the empirical and theoretical study in this field. His empirical studies include the description of allometric growth of national various indicators, the allometric growth of corporation, and allometric growth of Internet community. His theoretical studies include how to construct growing complex network model and explain different allometric growth phenomenon. Zhang is recently focusing on growing random geometric graph, allometric growth of complex network, and allometric growth of flow network. In the future, Zhang will shift his focus to explain the origin of allometric growth from the perspective of renormalization group and scale symmetry in complex network.
(3) Diversity in complex system
Diversity is another embodiment of complexity. Zhang focuses on the phenomenon of diversity in ecosystem, trade system and economic system, including the relation between diversity and scale, spatial distribution of diversity, and formation mechanism of diversity, etc.
Undergraduate courses: Foundation and Application of Matlab, Computer Modeling and
Simulation, Macro Economics
Postgraduate courses: Artificial Intelligence, Systems Science, System Theory Progress