Northeastern University (China)

About: Northeastern University (China) is a education organization based out in Shenyang, China. It is known for research contribution in the topics: Microstructure & Control theory. The organization has 36087 authors who have published 36125 publications receiving 426807 citations. The organization is also known as: Dōngběi Dàxué & Northeastern University (东北大学).

Predicting Temporal Social Contact Patterns for Data Forwarding in Opportunistic Mobile Networks

Abstract: In this paper, we predict nodes’ social contact patterns from the temporal perspective, and propose a novel approach to improve the performance of data forwarding in opportunistic mobile networks (OMNs). Specifically, considering both the average separating time and the variance of the separating time, we first introduce the definition of temporal closeness and temporal centrality. Then, several intuitive prediction methods are designed to predict nodes’ future temporal social contact patterns based on the observations from extensive real trace-driven simulation results. Afterward, based on the predicted temporal social contact patterns, we propose an efficient temporal closeness and centrality-based data forwarding strategy named TCCB for OMNs. The core idea of TCCB is to capture and utilize the temporal correlations to infer the future temporal social contact patterns in the remaining valid time of the data. Finally, extensive real trace-driven simulations are conducted to evaluate the performance of TCCB. The results show that TCCB is close to Epidemic in terms of delivery ratio but with significantly reduced delivery cost. Furthermore, TCCB performs much better than Bubble Rap and Prophet in terms of delivery ratio, but the delivery cost of TCCB is very close to that of Bubble Rap.

Line Impedance Cooperative Stability Region Identification Method for Grid-Tied Inverters Under Weak Grids

Abstract: Although the low-frequency/harmonic oscillation of grid-tied inverters under weak grids has been widely researched, the classical impedance-based approach focuses more on the identification of stable operating points and the stability margin of return-ratio matrix. Furthermore, it cannot provide stability regions of system parameters. Therefore, this paper proposes a line impedance cooperative stability region identification method. Firstly, the output impedance matrix and the input admittance matrix are respectively built in $d-q$ axis. Secondly, a novel stability forbidden region is proposed. It is less conservative than the forbidden region criteria in existing literatures. Based on the stability forbidden region, the stability operation region is established via mirror, translation and rotation mappings. It is less conservative compared with the norm-based stability criteria. The solving of stability operation region is first transformed into the eigenvalue identification problem in this paper. Furthermore, the detailed line impedance cooperative stability region is solved by guardian map theory. It can provide guidance for system planning and stabilization method researches with simplified computational process. Finally, the simulation and experimental results show that the proposed line impedance cooperative stability region identification method is more effective and less conservative.