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475 results on '"Li, Jun Yi"'

31. Optimal Transmission Scheduling over Multi-hop Networks: Structural Results and Reinforcement Learning

Author

Yang, Lixin, Xu, Yong, Lv, Weijun, Li, Jun-Yi, Shi, Ling, Yang, Lixin, Xu, Yong, Lv, Weijun, Li, Jun-Yi, and Shi, Ling

Abstract

This paper studies the optimal transmission scheduling for remote state estimation over multi-hop networks. A smart sensor observes a dynamic system, and sends its local state estimate to a remote estimator (RE). To save energy, multi-hop networks are deployed to relay data packets from the smart sensor to the RE. The smart sensor needs to decide the hop number communicating with the RE by adjusting its transmission power. To minimize the estimation error and the energy consumption, the transmission scheduling is formulated as a modified Markov decision process (MDP) by incorporating historical actions into the state. A sufficient condition is constructed to guarantee that the MDP has an optimal deterministic and stationary policy. The optimal policy's structure is further obtained to reduce the computation complexity. A deep reinforcement learning (DRL) algorithm, i.e., dueling double Q-network (D3QN), is introduced to obtain a near-optimal policy. Finally, a simulation example is provided to illustrate the developed results. IEEE

Published
2024

34. Reinforcement Learning-Based Distributed Robust Bipartite Consensus Control for Multispacecraft Systems With Dynamic Uncertainties

Author

Zhang, Yongwei and Li, Jun-Yi

Abstract

In this article, the reinforcement learning-based distributed robust bipartite consensus control of multispacecraft systems with dynamic uncertainties is investigated. The developed control structure includes two parts, i.e., integral sliding mode control and distributed optimal bipartite consensus control. In the first step, an integral sliding mode controller is designed for each following spacecraft to address matched uncertainties such that the dynamics of nominal spacecraft is obtained. In the second step, a novel performance index function, which contains consensus errors and their derivatives, is designed for each nominal spacecraft. As a result, the system assumption of zero equilibrium and the discount factor in performance index function are not required, which simplifies the controller design process and improves the practicability of the developed control method. Moreover, in order to solve the coupled Hamilton–Jacobi–Bellman equation of each following spacecraft, a novel policy iteration algorithm is designed and its properties are analyzed. Finally, a group of spacecraft is employed to verify the effectiveness of the present control scheme.

Published
2024
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39. Kinetics of pyrolysis and Computational Fluid Dynamics modeling of low metamorphic coal.

Author

Zhang, Qiu Li, Li, Jun Yi, Wang, Hai Xuan, Liu, Jun Li, and Zhou, Jun

Subjects
*COMPUTATIONAL fluid dynamics, *PYROLYSIS kinetics, *ACTIVATION energy, *FUNCTIONAL groups, *FLOW velocity
Abstract

This study explores the low‐temperature pyrolysis kinetic of low metamorphic grade coal from Northern Shaanxi, utilizing Fourier transform infrared (FT‐IR) spectroscopy to analyze the characteristics of various functional groups over a 293–1023 K temperature range. A kinetic model, correlating with the pyrolysis behaviors of these groups, was developed through thermal analysis kinetics. Computational fluid dynamics (CFD) technology simulated the furnace's flow dynamics, allowing an examination of the physical field alterations and functional group evolution during pyrolysis. Results showed that the pyrolysis kinetic functions for aromatic C–H, C=C, C–O, and •OH, along with temperature, pressure, and velocity fields, were successfully integrated into the simulation. This integration provided detailed insights into the temperature profile, pressure distribution, flow velocities, and functional group distribution in the furnace. Aliphatics, exhibiting the largest mass fraction and wide pyrolysis temperature range, and •OH radicals with the highest activation energy were concentrated in the furnace's pyrolysis zone center. C=C's distribution was influenced by aromatic C–H and aliphatics, showing a complementary pattern. The oxygen‐containing groups C–O and C=O had similar pyrolysis mechanisms and uniform distribution. The functional groups' mass fractions were ranked from highest to lowest as follows: aliphatics > •OH > aromatic C–H > C–O > C=C > C=O. [ABSTRACT FROM AUTHOR]

Published
2024
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40. Polyhedral {Ag12} and {Ag16} Clusters: Synthesis, Structural Characterization and Third‐Order Nonlinear Optical Properties.

Author

Xie, Hong‐Ping, Jin, Xiao‐Hang, Li, Jun‐Yi, Du, Ming‐Hao, Song, Ying‐Lin, and Lang, Jian‐Ping

Subjects
POLYHEDRA, OPTICAL properties, IRRADIATION, LASERS, ABSORPTION
Abstract

Two polyhedral silver‐thiolate clusters, [S@Ag16(Tab)10(MeCN)8](PF6)14 (Ag16) and [Ag12(Tab)6(DMF)12](PF6)12 (Ag12), were synthesized by using electroneutral Tab species as protective ligands (Tab=4‐(trimethylammonio)benzenethiolate, DMF=N,N‐dimethylformamide, MeCN=acetonitrile). Ag16 has a decahedral shape composed of eight pentagon {Ag5} units and two square {Ag4} units. The structure of Ag12 is a cuboctahedron, a classical Archimedean structure composed of six triangular faces and eight square faces. The former configuration is discovered in silver‐thiolate cluster for the first time, possibly benefited from the more flexible coordination between the Tab ligand and Ag+ facilitated by the electropositive −N(CH3)3+ substituent group. Third‐order nonlinear optical studies show that both clusters in DMF exhibit reverse saturate absorption response under the irradiation of 532 nm laser. [ABSTRACT FROM AUTHOR]

Published
2024
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