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851 results on '"Gao, Gang"'

3. ARGET ATRP of styrene with low catalyst usage in bio-based solvent γ-valerolactone

Author

Zhu Qianqian, Song Tianchen, Zhao Jiaxin, Gao Gang, Xiang Yixin, Gao Jiangang, and Shen Xianrong

Subjects
styrene polymerization, green solvent, arget atrp, γ-valerolactone, living radical polymerization, Polymers and polymer manufacture, TP1080-1185
Abstract

The application of bio-based solvents for living radical polymerization has been a hot topic in recent year. In this article, γ-valerolactone (GVL), a bio-based solvent as green media for ARGET atom transfer radical polymerization (ATRP) of styrene (St) were investigated. We first conducted polymerization of St in γ-valerolactone using copper(ii) bromide as the catalyst, tris(2-pyridylmethyl) amine as the ligand, and only sodium ascorbate as reducing agent. The polymerization achieved moderate conversion; however, the controllability of polymerization was not very good, providing a polymer with a broad molecular weight distribution (M w/M n > 1.30). When sodium carbonate is introduced, excellent results were obtained providing high yields and low M w/M n values under very low catalyst usage (∼5 ppm). 1H NMR spectroscopy, chain extension, and MALDI–MS experiments confirmed the final polymer chains with high fidelity. The use of GVL solvent opens a new route for the easy synthesis of PS through ARGET ATRP with low catalyst usage conditions.

Published
2024
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4. Floor failure characteristics and safety evaluation of upper coal mining with underlying semi-goaf

Author

ZHOU Jinyan, ZHAO Lisong, WEI Haohao, and GAO Gang

Subjects
semi-goaf, floor warning layer, ratio of floor and roof event frequency, energy density, floor failure depth, Mining engineering. Metallurgy, TN1-997
Abstract

In the process of upper coal mining, the floor condition may be incomplete because of the lower coal goaf, and the change of the floor condition has an obvious influence on the floor failure in the upper coal mining. Based on the micro-seismic monitoring data of 15249S working face in Jiulong Mine, the activity of floor events, the ratio of roof to floor, energy and other parameters are statistically analyzed. The results show that: when the lower coal is a gob, the activity of floor events is strong and the disturbance depth is large when the upper coal is mined. With the advance of mining location and the change of underlying coal seam conditions, the frequency ratio of floor and roof events changes greatly, and its change rule is consistent with the formation of water channel. The proportion of micro-seismic events increased by 16.49% and decreased by 10.92% when the bottom floor failure depth was 0-5 m and 5-20 m respectively. In the process of overlying coal stoping approaching the underlying stoping contact roadway, the development location of large energy events extends from shallow to deep. The floor safety evaluation system is constructed by using the parameters of floor warning layer event activity, floor and roof event ratio, distance from the stoping line of the underlying coal seam and vertical energy density. The danger zone before and after the stoping position of the underlying working face is a high risk factor, which can be combined with the changes of safety evaluation parameters for early warning and strengthening hydro-geological observation.

Published
2024
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6. The Brain-Inspired Cooperative Shared Control for Brain-Machine Interface

Author

Zheng, Shengjie, Liu, Ling, Yang, Junjie, Qian, Lang, Gao, Gang, Chen, Xin, Jin, Wenqi, Deng, Chunshan, and Li, Xiaojian

Subjects
Computer Science - Robotics, Computer Science - Human-Computer Interaction, Electrical Engineering and Systems Science - Systems and Control
Abstract

In the practical application of brain-machine interface technology, the problem often faced is the low information content and high noise of the neural signals collected by the electrode and the difficulty of decoding by the decoder, which makes it difficult for the robotic to obtain stable instructions to complete the task. The idea based on the principle of cooperative shared control can be achieved by extracting general motor commands from brain activity, while the fine details of the movement can be hosted to the robot for completion, or the brain can have complete control. This study proposes a brain-machine interface shared control system based on spiking neural networks for robotic arm movement control and wheeled robots wheel speed control and steering, respectively. The former can reliably control the robotic arm to move to the destination position, while the latter controls the wheeled robots for object tracking and map generation. The results show that the shared control based on brain-inspired intelligence can perform some typical tasks in complex environments and positively improve the fluency and ease of use of brain-machine interaction, and also demonstrate the potential of this control method in clinical applications of brain-machine interfaces., Comment: This article need to update the corrected figure and data

Published
2022

42. Adaptive Fixed-Time Cooperative Guidance Law Based on Integral Sliding Mode

Author

Gao Jiwei, Zhang Jinpeng, Gao Gang, He Jingang, Xu Xingyuan

Subjects
cooperative guidance, cooperative control, adaptation, attack time consistency, integral sliding mode, communication topology, missile, Motor vehicles. Aeronautics. Astronautics, TL1-4050
Abstract

For the problem of air-to-air missile cooperative attack on high-speed maneuvering target, a multi-missile cooperative guidance law with consistent attack time is proposed. Firstly, the geometric model of engagement between each missile and target is established in the longitudinal plane, and the relationship between the radial and normal guidance laws of line of sight and the normal acceleration of velocity is analyzed. Then, the fixed time cooperative control law is designed, and based on the line of sight dynamic equation, the robust cooperative guidance law with attack-time constraint is established by using adaptive law and integral sliding mode algorithm to ensure that multiple missiles hit the maneuvering target at the same time. Through numerical simulation, the difference of cooperative time and miss distances are 0.001 s and 0.01 m respectively. The final results verify the effectiveness and rationality of the fixed-time cooperative guidance law.

Published
2022
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