National University of Defense Technology

About: National University of Defense Technology is a education organization based out in Changsha, China. It is known for research contribution in the topics: Radar & Synthetic aperture radar. The organization has 39430 authors who have published 40181 publications receiving 358979 citations. The organization is also known as: Guófáng Kēxuéjìshù Dàxué & NUDT.

A Collaborative Multi-Agent Reinforcement Learning Anti-Jamming Algorithm in Wireless Networks

Abstract: In this letter, we investigate the anti-jamming defense problem in multi-user scenarios, where the coordination among users is taken into consideration. The Markov game framework is employed to model and analyze the anti-jamming defense problem, and a collaborative multi-agent anti-jamming algorithm (CMAA) is proposed to obtain the optimal anti-jamming strategy. In sweep jamming scenarios, on the one hand, the proposed CMAA can tackle the external malicious jamming. On the other hand, it can effectively cope with the mutual interference among users. Moreover, we consider the impact of sensing errors due to miss detection and false alarm. Simulation results show that the proposed CMAA is superior to both sensing-based method and independent ${Q}$ -learning method, and has the highest normalized rate.

Angular Dependence of Exchange Bias and Magnetization Reversal Controlled by Electric‐Field‐Induced Competing Anisotropies

Abstract: The combination of exchange-biased systems and ferroelectric materials offers a simple and effective way to investigate the angular dependence of exchange bias using one sample with electric-field-induced competing anisotropies. A reversible electric-field-controlled magnetization reversal at zero magnetic field is also realized through optimizing the anisotropy configuration, holding promising applications for ultralow power magnetoelectric devices.

Silicone rubber ablative composites improved with zirconium carbide or zirconia

Abstract: Silicone rubber ablative composites with zirconium carbide (ZrC) or zirconia (ZrO2) were prepared and tested for thermal protection systems. The incorporation of ZrC or ZrO2 powders increased the tensile strength but reduced the elongation at break of the composites. The thermal stabilities of the composites were enhanced by adding ZrC or ZrO2. The ceramic layers containing ZrO2, SiO2 and SiC were formed on the ablated surface of the composites with ZrO2 or ZrC, and acted as effective oxygen and heat barriers. The ablated surface of the composite with ZrO2 was more uniform than that of the composite with ZrC in the experiment. The linear ablation rates of the composites were reduced by 40% and 72% by the incorporation of 40 phr ZrC and ZrO2, respectively.