Measuring node contributions to network users in directed networks

We focus on the role of the network user played in real-world networks. First, we introduce the user cocoon structure of a user in a directed network. Second, to characterize the contributions of nodes in the user cocoon, we propose the structural contribution of a node to a network user based on the structure of the network. Then, we propose the user centrality of a node, as an improvement of node structural contribution, by introducing the random walk theory and the PageRank strategy. Node user centrality measures node potential to ensure successful transportation for network users. Simulation results show that it is a proper measurement to quantify the contributions or importance of nodes to network users and it has a strong ability to characterize nodes well by distinguishing node importance.