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: Control theory & Microstructure. 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).

Adaptive Output-Feedback Neural Control of Switched Uncertain Nonlinear Systems With Average Dwell Time

Abstract: This paper investigates the problem of adaptive neural tracking control via output-feedback for a class of switched uncertain nonlinear systems without the measurements of the system states. The unknown control signals are approximated directly by neural networks. A novel adaptive neural control technique for the problem studied is set up by exploiting the average dwell time method and backstepping. A switched filter and different update laws are designed to reduce the conservativeness caused by adoption of a common observer and a common update law for all subsystems. The proposed controllers of subsystems guarantee that all closed-loop signals remain bounded under a class of switching signals with average dwell time, while the output tracking error converges to a small neighborhood of the origin. As an application of the proposed design method, adaptive output feedback neural tracking controllers for a mass-spring-damper system are constructed.

Is Cobalt Needed in Ni-Rich Positive Electrode Materials for Lithium Ion Batteries?

Abstract: As a derivative of LiNiO2, NCA (LiNi1-x-yCoxAlyO2) is widely used in the electric vehicle industry because of its high energy density. It is thought that Co and Al both play important roles in enhancing NCA material properties. However, there is no solid evidence in the literature that clearly shows that Co is required in NCA with high nickel (e.g. when 1-x-y > 0.9) content. Therefore, a systematic study on the roles of different cation substituents in a series of LiNi1-nMnO2 (M = Al, Mn, Mg, or Co) materials was made. In-situ X-ray diffraction (XRD) and differential capacity versus voltage (dQ/dV vs. V) studies showed that the multiple phase transitions in LixNiO2 during charge and discharge, thought to cause poor charge-discharge capacity retention, were suppressed in LixNi0.95M0.05O2 (M = Al, Mn, or Mg), while 5% Co failed to suppress the phase transitions. First principles calculations were made to understand the function of each substituent. Accelerating rate calorimetry shows that unlike Al, Mn, or Mg, Co has no contribution to safety improvement. Therefore, we believe that Co brings little or no value at all to NCA-type materials with high Ni content (> 90% Ni in the transition metal layer) and we hope this paper will spur more interest in Co-free materials.