University of Science and Technology Beijing

About: University of Science and Technology Beijing is a education organization based out in Beijing, China. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 41558 authors who have published 44473 publications receiving 623229 citations. The organization is also known as: Beijing Steel and Iron Institute.

Vibration Control of a Flexible Robotic Manipulator in the Presence of Input Deadzone

Abstract: In this paper, a neural network (NN) controller is designed to suppress the vibration of a flexible robotic manipulator system with input deadzone. The NN aims to approximate the unknown robotic manipulator dynamics and eliminate the effects of input deadzone in the actuators. In order to describe the system more accurately, the model of the flexible manipulator is constructed based on the lumping spring-mass method. Full state feedback NN control is proposed first and output feedback NN control with a high-gain observer is then devised to make the proposed control scheme more practical. The effect of input deadzone is approximated by a radial basis function neural network (RBFNN) and the unknown dynamics of the manipulator is approximated by another RBFNN. The proposed NN control is able to compensate for the estimated deadzone effect and track the desired trajectory. For the stability analysis, the Lyapunov's direct method is used to ensure uniform ultimate boundedness (UUB) of the closed-loop system. Simulations are given to verify the control performance of the NN controllers comparing with the proportional derivative (PD) controller. At last, the experiments are conducted on the Quanser platform to further prove the feasibility and control performance of the NN controllers.

Realizing over 10% efficiency in polymer solar cell by device optimization

Abstract: The low band gap polymer based on benzodithiophene (BDT)-thieno[3,4-b]thiophene (TT) backbone, PBDT-TS1, was synthesized following our previous work and the bulk heterojunction (BHJ) material comprising PBDT-TS1/PC71BM was optimized and characterized. By processing the active layer with different additives i.e. 1,8-diiodooctane (DIO), 1-chloronaphthalene (CN) and 1, 8-octanedithiol (ODT) and optimizing the ratio of each additive in the host solvent, a high PCE of 9.98% was obtained under the condition of utilizing 3% DIO as processing additive in CB. The effect of varied additives on photovoltaic performance was illustrated with atomic force microscopy (AFM) and transmission electron microscope (TEM) measurements that explained changes in photovoltaic parameters. These results provide valuable information of solvent additive choice in device optimization of PBDTTT polymers, and the systematic device optimization could be applied in other efficient photovoltaic polymers. Apparently, this work presents a great advance in single junction PSCs, especially in PSCs with conventional architecture.

Toward the Application of High Frequency Electromagnetic Wave Absorption by Carbon Nanostructures

Abstract: With the booming development of electronic information technology, the problems caused by electromagnetic (EMs) waves have gradually become serious, and EM wave absorption materials are playing an essential role in daily life. Carbon nanostructures stand out for their unique structures and properties compared with the other absorption materials. Graphene, carbon nanotubes, and other special carbon nanostructures have become especially significant as EM wave absorption materials in the high-frequency range. Moreover, various nanocomposites based on carbon nanostructures and other lossy materials can be modified as high-performance absorption materials. Here, the EM wave absorption theories of carbon nanostructures are introduced and recent advances of carbon nanostructures for high-frequency EM wave absorption are summarized. Meanwhile, the shortcomings, challenges, and prospects of carbon nanostructures for high-frequency EM wave absorption are presented. Carbon nanostructures are typical EM wave absorption materials being lightweight and having broadband properties. Carbon nanostructures and related nanocomposites represent the developing orientation of high-performance EM wave absorption materials.