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2nd International Conference on Computer Engineering and Application, ICCEA 2021

作者： Lv, Fengrong Dong, Zeyu Wan, Tao Jiang, Kaili Fang, Xueli Zhang, Lei University of Electronic Science and Technology of China School of Information and Communication Engineering Chengdu China Key Laboratory of Complex Aviation Simulation System Beijing China

ISBN: (纸本)9781665426169

The ambiguity function describes the joint characteristics of the signal in the time domain and the frequency domain, and is usually used for signal recognition. The time domain and frequency domain distribution of noise is more spurious than the signal. Its ambiguity function can also reflect its characteristics. However, the direct use of the ambiguity function as the signal feature will increase the amount of calculation of the detection system, so slice it, which reduces the burden on the system for detecting signal information while preserving the information. At the same time, the radar signal detection based on neural network can avoid the influence of artificially setting the threshold on the detection performance of the system. So, we propose an algorithm for inputting the extracted fuzzy function slice sequence into a neural network to realize signal detection. simulation proves that when the signal-To-noise ratio of the received signal is very low, our proposed method still has a high detection probability. © 2021 IEEE.

关键词： Signal detection

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Study on Microstructure and Corrosion Behavior of Welded Joints of 2a12 and 2a97 Aluminum Alloys by Fsw

SSRN

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SSRN 2024年

作者： Li, Wen Li, Shaojie Nan, Yang Bai, Xuepiao Li, Weiping School of Materials Science and Engineering Beihang University Beijing100191 China Aviation Key Laboratory of Science and Technology on Advanced Surface Engineering AVIC Manufacturing Technology Institute Beijing100024 China

T-shaped joints of high-strength aluminum alloy welded by friction stir welding (FSW) are expected to replace the traditional riveting structures. However, the corrosion of T-joint still hinder the popularization of FSW in aerospace industry. Herein, T-joints of 2A12 and 2A97 aluminum alloys are prepared and studied via structural characterization and corrosion tests. The microstructures and constituents of different micro zones in T-joints before and after corrosion tests are characterized and analyzed particularly. The internal relationship between different micro zones in T-joints and their corrosion behaviors are clarified, which provides theoretical basis for improving welding process and surface protection after welding. © 2024, The Authors. All rights reserved.

关键词： Friction stir welding

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HMAFlow: Learning More Accurate Optical Flow via Hierarchical Motion Field Alignment

arXiv

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arXiv 2024年

作者： Ma, Dianbo Imamura, Kousuke Gao, Ziyan Wang, Xiangjie Yamane, Satoshi Graduate School of Natural Science & Technology Kanazawa University Japan Information Science Japan Advanced Institute of Science and Technology Japan State Key Laboratory of Automotive Simulation and Control Jilin University China

Optical flow estimation is a fundamental and longstanding visual task. In this work, we present a novel method, dubbed HMAFlow, to improve optical flow estimation in challenging scenes, particularly those involving small objects. The proposed model mainly consists of two core components: a Hierarchical Motion Field Alignment (HMA) module and a Correlation Self-Attention (CSA) module. In addition, we rebuild 4D cost volumes by employing a Multi-Scale Correlation Search (MCS) layer and replacing average pooling in common cost volumes with a search strategy utilizing multiple search ranges. Experimental results demonstrate that our model achieves the best generalization performance compared to other state-of-the-art methods. Specifically, compared with RAFT, our method achieves relative error reductions of 14.2% and 3.4% on the clean pass and final pass of the Sintel online benchmark, respectively. On the KITTI test benchmark, HMAFlow surpasses RAFT and GMA in the Fl-all metric by relative margins of 6.8% and 7.7%, respectively. To facilitate future research, our code will be made available at https://***/BooTurbo/HMAFlow. Copyright © 2024, The Authors. All rights reserved.

关键词： Motion estimation

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粉末床熔融的多材料铺粉过程中粉末扩散的数值研究

引用

Acta Mechanica Sinica 2023年第1期39卷 23-29页

作者：王林李二垒周宗彦张百成余艾冰 ARC Hub for Computational Particle Technology Department of Chemical & Biological Engineering Monash University Clayton VIC 3800 Australia Delft University of Technology Stevinweg 1 2628 CN Delft The Netherlands Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems Jiangxi University of Science and Technology Nanchang 330013 China Beijing Advanced Innovation Center Materials Genome Engineering Advanced Material & Technology Institute University of Science and Technology Beijing Beijing 100083 China

粉末床熔融增材制造技术已应用于功能梯度材料的制造.文献中报道了一种材料成分沿垂直于粉末铺粉方向变化的新设计.基于此设计,本工作采用离散单元数值模拟研究了两种密度差异较大的金属粉末在铺粉过程中颗粒的偏析情况.结果发现,在铺... 详细信息

粉末床熔融增材制造技术已应用于功能梯度材料的制造.文献中报道了一种材料成分沿垂直于粉末铺粉方向变化的新设计.基于此设计,本工作采用离散单元数值模拟研究了两种密度差异较大的金属粉末在铺粉过程中颗粒的偏析情况.结果发现,在铺粉过程中,较大密度粉末(重颗粒)一侧的铺粉量小于较小密度粉末(轻颗粒)的一侧的铺粉量.这种现象表明重颗粒从粉末密度大的一侧向粉末密度较小的一侧扩散.这种扩散受铺粉速度影响较大,铺粉速度越快,扩散越明显.但粉末层厚度对扩散影响不大.结果还表明,重颗粒与轻颗粒间的粒径差异影响扩散较大,减小重颗粒的粒径可能是控制颗粒偏析的一种方案.

关键词：材料成分颗粒偏析功能梯度材料离散单元金属粉末密度差异增材制造技术扩散影响

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Time-varying reliability analysis based on improved toughness exhaustion model and probability density evolution method to predict fatigue damage life

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Engineering Fracture Mechanics 2022年第PartB期276卷

作者： Xu, Huimin Liu, Yating Zhao, Gongwei Ye, Nanhai Key Laboratory of Advanced Design and Simulation Technology for Special Equipment Ministry of Education Hunan University Changsha410082 China

This paper proposed an improved toughness exhaustion model through introducing a stress ratio weighting factor k. Specifically, the k is adopted as a coefficient of the stress amplitude ratio into the damage equivalence equation, which can reflect the influences of loading sequence and interaction effect simultaneously. Then, the value range of k is determined from the theoretical derivation and experimental verification. The experimental results have shown that the improved model can predict the residual life more precisely. Moreover, to solve the problem of the stochastic uncertainty of the fatigue life, the damage state equation using the improved model is evaluated by the probability density evolution method (PDEM). Finally, two sets of experimental data under two-level were used for model validation. Results indicate that the accuracy of time-varying fatigue reliability can be improved with the proposed model. © 2022 Elsevier Ltd

关键词： Reliability analysis

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Ultra-wide-field-of-view high-resolution cascaded spectral imaging system

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Optics Express 2025年第10期33卷 22030-22041页

作者： Li, Xuhui Gao, Yanhong Xue, Rudong Ji, Yiqun Sun, Shujun School of Optoelectronic Science and Engineering Soochow University Suzhou215006 China School of Optical and Electronic Information Suzhou City University Suzhou Key Laboratory of Biophotonics Suzhou215104 China Nanjing Research Institute on Simulation Technique Nanjing210016 China Collaborative Innovation Center of Suzhou Nano Science and Technology & Engineering Research Center of Digital Imaging and Display of Education Ministry of China Soochow University Suzhou215006 China Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province & Key Lab of Modern Optical Technologies of Education Ministry of China Soochow University Suzhou215006 China

Spectral imaging combines the advantages of spectroscopy as an analytical tool with the two-dimensional object visualization obtained by optical imaging. At present, spectral imaging systems suffer from severe scale-dependent geometric aberrations. This prevents the simultaneous realization of a wide field of view (FOV) and high resolution. Here we propose an ultra-wide-FOV high-resolution cascaded spectral imaging system (URIS), which captures an ultra-wide-FOV panchromatic image with a folding monocentric lens and obtains high-resolution spectral images after local aberration correction by the spectral imaging sub-channels. The key issue of how the position of the aperture stop affects the illumination uniformity of the sub-channels has been studied, contributing to achieving the spectral images stitching between adjacent sub-channels and improving the performance of the processed spectral image. The URIS is optimally designed with 19 spectral imaging sub-channels to cover a full FOV of about 110°. It achieves an excellent spatial resolution of 0.075 mrad and a high spectral resolution of 4 nm theoretically. An experiment is also demonstrated to verify the wide FOV and the uniformity of sub-channels of URIS, confirming the correctness of the theoretical study. URIS has great advantages in spectral imaging of large macroscopic scenes, inspiring various machine vision applications. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Imaging systems Optical components Optical imaging Optical systems Spatial resolution Systems design

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Symmetry-oriented enumeration method for molecular crystal structure prediction and its application

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Physical Review B 2025年第13期111卷 134112-134112页

作者： Yu Xin Zhuohang Xie Yongshuo Chen Pengyue Gao Hong Jian Zhao Jian Lv Yanchao Wang Yanming Ma Key Laboratory of Material Simulation Methods and Software of Ministry of Education College of Physics Jilin University Changchun 130012 China International Center of Future Science Jilin University Changchun 130012 China Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education) College of Physics Jilin University Changchun 130012 China State Key Laboratory of High Pressure and Superhard Materials College of Physics Jilin University Changchun 130012 China

Predicting the thermodynamically stable arrangements of molecular building blocks is crucial for understanding the properties and behaviors of crystalline molecular compounds. Several molecular structure prediction methods have been proposed, leading to successful applications. However, some evolutionary approaches that involve direct sampling within the infinite atomic coordinate space, without symmetry-preserving constraints, tend to suffer from biased sampling, where structures with P1 symmetry become disproportionately dominant. To overcome this limitation, we propose a method that utilizes a finite set of symmetrically inequivalent Wyckoff encodes to sparsely represent the search space of crystalline molecular compounds, thereby improving the coverage of the search space. This method can be used to predict the molecular crystal structures with varying numbers of molecules in the asymmetric unit, from fractional to multiple integers. The applications of this method to three-dimensional molecular crystals of ammonia dihydrate, the NH3−H2O−CH4 mixture, and two-dimensional layered ices revealed a series of energetically quasidegenerate structures with diverse crystal packing motifs. This method expands the scope and utility of molecular building blocks for designing stable molecular crystals, providing a robust framework for achieving extensive tunability in molecular materials design.

关键词： Molecular crystals

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Rotary Bending Process and Parameter Optimization of Rectangular Tube with Variable-Section 12th

Rotary Bending Process and Parameter Optimization of Rectang...

引用

12th International Conference on advanced Materials and Engineering Materials, ICAMEM 2023

作者： Zhao, Xinhai Wang, Xinghui Sun, Xingchen Zheng, Chao Jiang, Zhengyi State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan250061 China Mechanical Materials Mechatronic and Biomedical Engineering University of Wollongong Wollongong2522 Australia China Aviation Lithium Battery Co. Ltd Luoyang471000 China Unit 32128 of the Chinese People’s Liberation Army Jinan250061 China

ISBN: (纸本)9789819735297

Aiming at the bending process of ordinary rectangular tube, the influence of parameters such as friction coefficient, corner radius of tube blank, and rotational speed of bending die on the bending defects was studied. The traditional rotary bending process was improved and proposed the non-mandrel anti-compensation process. For the variable-section rectangular tube, a variable-radius bending die was designed. For a certain size of variable-section rectangular tube, the anti-compensation parameters of each part were optimized. Take the minimum of internal folding and external depression as the optimization goal, the influence law of different parameters was obtained, and two sets of optimization parameters were obtained. Then, the two sets of parameters were analyzed using the comprehensive equilibrium method. Finally, a set of optimal process parameters was obtained. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

关键词： Tubes (components)

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The evolution and degradation mechanisms of microstructure, mechanical and microwave absorption performance in RA SiC fibers

引用

Materials Characterization 2025年 225卷

作者： Hou, Wanbo Li, Hanxiang Feng, Tao Shi, Xinhao Ding, Jiahui Han, Dongcheng Lu, Pengkang Lin, Hongjiao Tong, Mingde State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi'an710072 China of Technology Innovation for Advanced Aviation Equipment Corporation Sichuan 610031 China

This work systematically investigates the high-temperature evolution (800–1600 °C) of microstructure, mechanical behaviors and microwave absorption characteristics in RA SiC fibers. The failure mechanisms of the fibers under high-temperature conditions were elucidated. The original fibers demonstrate moderate mechanical strength (1.77 GPa) and exceptional microwave absorption performance. SiC fiber fabric with a thickness of 2.56 mm achieved a minimum reflection loss (RLmin) of −61.19 dB at 9.56 GHz. While the effective absorption bandwidth (EAB, RL ≤ -10 dB) spanned the entire X-band (8.2–12.4 GHz). At 1200 °C, SiC fibers maintained 96.8 % mechanical strength. However, thermal decomposition of SiCxOy phase and crystallization of β-SiC begin to occur, resulting in a decrease in RLmin to −22.07 dB (EAB = 4.2 GHz). Above 1200 °C, accelerated SiCxOy phase decomposition and β-SiC grain coarsening induced microstructural defects and conductivity enhancement, severely compromising impedance matching and mechanical integrity. Therefore, tensile strength plummets to 0.25 GPa at 1600 °C, and accompanied by a functional transition from microwave absorption to electromagnetic shielding. Ultimately, the 0.2 mm-thick fiber fabric achieves an average shielding effectiveness of 11 dB (90 % shielding efficiency) across the X-band. © 2025 Elsevier Inc.

关键词： Tensile strength

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Switching Control Method for Optimal State Feedback Controller of Nuclear Reactor Power System

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Journal of Applied Mathematics and Physics 2023年第8期11卷 2480-2490页

作者： Airan Dang Bowen Tu Xiuchun Luan Heilongjiang Provincial Key Laboratory of Nuclear Power System and Equipment Harbin Engineering University Harbin China Key Laboratory of Nuclear Safety and Advanced Nuclear Energy Technology Ministry of Industry and Information Technology Harbin Engineering University Harbin China Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering University Harbin China

Due to the nonlinearity of the reactor power system, the load tracking situation is closely related to the initial steady-state power and the final steady-state power after the introduction of the state feedback controller. Therefore, when the initial power and the final stable power are determined, the particle swarm optimization algorithm is used to find the optimal controller parameters to minimize the load tracking error. Since there are many combinations of initial stable power and final stable power, it is not possible to find the optimal controller parameters for all combinations, so the neural network is used to take the final stable power and the initial stable power as input, and the optimal controller parameters as the output. This method obtains the optimal state feedback controller switching control method can achieve a very excellent load tracking effect in the case of continuous power change, in the power change time point, the response is fast, in the controller parameter switching time point, the actual power does not fluctuate due to the change of controller parameters. .

关键词： Optimal Status Feedback Particle Swarm Optimization Neural Networks Controller Switching Control Load Tracking

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