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Your search keyword '"Zeng, Liangcai"' showing total 310 results
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310 results on '"Zeng, Liangcai"'

1. Numerical Analysis on the Spatiotemporal Characteristics of the Portevin-Le Chatelier Effect in Ti-12Mo Alloy

Author

Luo, Shiyuan, Jiang, Yongxin, Thuillier, Sandrine, Castany, Philippe, and Zeng, Liangcai

Subjects
Physics - Classical Physics
Abstract

A simplified 3D FE model based on McCormick's model is developed to numerically predict the spatiotemporal behaviors of the PLC effect in Ti-12Mo alloy tensile tests at 350 degrees C with strain rates from the order of $10^{-4}$ s$^{-1}$ to $10^{-2}$ s$^{-1}$. The material parameter identification procedure is firstly presented in details, and the simulated results are highly consistent with experimental ones, especially in terms of stress drop magnitudes and PLC band widths. The distribution of simulated stress drop magnitudes at a constant tensile velocity (0.01 mm/s) follows a normal distribution and its peak value is in the range of 26-28 MPa. Furthermore, the simulated band width slightly fluctuates with the increase of true strain and its average value is about 1.5 mm. Besides, the staircase behavior of strain-time curves and the hopping propagation of the PLC band are observed in Ti-12Mo alloy tensile process, which are related to the strain localization and stress drop magnitudes.

Published
2024
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17. Robust Alignment of Multi-Exposed Images with Saturated Regions

Author

Jiang, Jun, Li, Zhengguo, Xie, Shoulie, Wu, Shiqian, and Zeng, Liangcai

Subjects
Electrical Engineering and Systems Science - Image and Video Processing, CS
Abstract

It is challenging to align multi-exposed images due to large illumination variations, especially in presence of saturated regions. In this paper, a novel image alignment algorithm is proposed to cope with the multi-exposed images with saturated regions. Specifically, the multi-exposed images are first normalized by using intensity mapping functions (IMFs) in consideration of saturated pixels. Then, the normalized images are coded by using the local binary pattern (LBP). Finally, the coded images are aligned by formulating an optimization problem by using a differentiable Hamming distance. Experimental results show that the proposed algorithm outperforms state-of-the-art alignment methods for multi-exposed images in terms of alignment accuracy and robustness to exposure values.

Published
2020

49. Tunable bandwidth terahertz perfect absorption device based on vanadium dioxide phase transition control.

Author

Shui, Bin, Yi, Yingting, Ma, Can, Yi, Zao, Li, Gongfa, Zeng, Liangcai, Zeng, Qingdong, Wu, Pinghui, and Yi, Yougen

Subjects
PHASE transitions, VANADIUM dioxide, ABSORPTION, IMPEDANCE matching, ELECTRIC impedance, VANADIUM
Abstract

Utilizing the phase transition principle of VO2, this paper presents a tunable ultra-wideband terahertz perfect absorption device with simple structure and tunability. The proposed broadband terahertz perfect absorption device is a three-layer structure with a metal reflective layer, a silicon dioxide dielectric layer and a VO2 layer from bottom to top. It was found that the terahertz perfect absorption device's absorption could be dynamically adjusted from 1.2% to 99.9% when changing from an insulated to a metallic state. With the VO2 in the metallic state, the terahertz perfect absorption device has an absorption efficiency of more than 90% in 4.00 to 10.08 THz's ultra-broadband range and near-perfect absorption is achieved in the ranges of 4.71 THz to 5.16 THz and 7.74 THz to 8.06 THz. To explain the working principle of this terahertz perfect absorption device, this paper utilizes wave interference's principle, theory of impedance matching and electric field analysis. Compared to previously reported terahertz metamaterial devices, the vanadium dioxide device proposed in this paper is significantly optimized in terms of tunable range and absorption bandwidth. In addition, the terahertz perfect absorption device is polarization insensitive and maintains good absorptivity over a wide-angle incidence range. This tunable ultra-wideband terahertz perfect absorption device could have applications in the fields of modulation, stealth devices, and thermal emission devices. [ABSTRACT FROM AUTHOR]

Published
2024
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