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21 results on '"Xu, Yunyan"'

3. Underwater Coherent Source Direction-of-Arrival Estimation Method Based on PGR-SubspaceNet.

Author

Guo, Tuo, Xu, Yunyan, Bi, Yang, Ding, Shaochun, and Huang, Yong

Subjects
DIRECTION of arrival estimation, UNDERWATER acoustics, SIGNAL-to-noise ratio, STANDARD deviations, COMPLEX variables
Abstract

In the field of underwater acoustics, the signal-to-noise ratio (SNR) is generally low, and the underwater environment is complex and variable, making target azimuth estimation highly challenging. Traditional model-based subspace methods exhibit significant performance degradation when dealing with coherent sources, low SNR, and small snapshot data. To overcome these limitations, an improved model based on SubspaceNet, called PConv-GAM Residual SubspaceNet (PGR-SubspaceNet), is proposed. This model embeds the global attention mechanism (GAM) into residual blocks that fuse PConv convolution, making it possible to capture richer cross-channel and positional information. This enhancement helps the model learn signal features in complex underwater conditions. Simulation results demonstrate that the underwater target azimuth estimation method based on PGR-SubspaceNet exhibits lower root mean square periodic error (RMSPE) values when handling different numbers of narrowband coherent sources. Under low SNR and limited snapshot conditions, its RMSPE values are significantly better than those of traditional methods and SubspaceNet-based enhanced subspace methods. PGR-SubspaceNet extracts more features, further improving the accuracy of direction-of-arrival estimation. Preliminary experiments in a pool validate the effectiveness and feasibility of the underwater target azimuth estimation method based on PGR-SubspaceNet. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Corrigendum to“PDL1-targeted vaccine exhibits potent antitumor activity by simultaneously blocking PD1/PDL1 pathway and activating PDL1-specific immune responsesˮ [Canc. Lett. 476 (2020) 170–182]

Author

Tian, Hong, primary, Kang, Yanliang, additional, Song, Xiaoda, additional, Xu, Yi, additional, Chen, Hongmei, additional, Gong, Xingqun, additional, Zhang, Wanli, additional, Xu, Yunyan, additional, Xia, Xuefei, additional, Gao, Xiangdong, additional, and Yao, Wenbing, additional

Published
2021
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15. Study on impact performances of scarf-repaired carbon fiber reinforced polymer laminates

Author

Liu Shufeng, Cheng Xiaoquan, Guo Xin, Xu Yunyan, and Bao Jianwen

Subjects
Carbon fiber reinforced polymer, Materials science, Polymers and Plastics, business.industry, Mechanical Engineering, Composite number, Stiffness, Poison control, Structural engineering, Composite laminates, Residual, Residual strength, Compressive strength, Mechanics of Materials, Materials Chemistry, Ceramics and Composites, medicine, medicine.symptom, Composite material, business
Abstract

Composite structures used in aircraft are vulnerable to low-velocity impact and replacing them with new ones requires significant cost. Scarf-repair technique is an effective method to restore the stiffness and strength of damaged composite structures. Previous studies on scarf-repaired composite laminates have focused on stiffness and strength recovery efficiency, but limited attention has been directed toward the impact properties. However, scarf-repaired composite laminates are also sensitive to low-velocity impact. The residual strength is worth investigating to ensure the safety of scarf-repaired composite structures. In this study, experiments were conducted to test the residual compression strength after impact. Two main factors, namely impact energy and location, were considered. Finite element models were established to analyze the influences of these two factors and to predict the residual strength. Impact damages were introduced by degrading the mechanical properties in the damaged area estimated through the C-scan photographs. Results indicated that the damage area was larger when the impact was applied at the bondline of the top surface and the residual strength was the smallest. Increasing the impact energy caused large damage area, in which the residual strength declined. The predicted residual strength agreed with the experimental results well.

Published
2014

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