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Multi-Material Topology Optimization of 2D Structures Using Convolutional Neural Networks

Computer Modeling in Engineering & Sciences 2024年第8期140卷 1919-1947页

作者： Jiaxiang Luo Weien Zhou Bingxiao Du Daokui Li Wen Yao College of Aerospace Science and Engineering National University of Defense TechnologyChangsha410073China defense innovation institute Chinese Academy of Military ScienceBeijing100071China Intelligent Game and Decision Laboratory Chinese Academy of Military ScienceBeijing100071China

In recent years,there has been significant research on the application of deep learning(DL)in topology optimization(TO)to accelerate structural ***,these methods have primarily focused on solving binary TO problems,and effective solutions for multi-material topology optimization(MMTO)which requires a lot of computing resources are still ***,this paper proposes the framework of multiphase topology optimization using deep learning to accelerate MMTO *** framework employs convolutional neural network(CNN)to construct a surrogate model for solving MMTO,and the obtained surrogate model can rapidly generate multi-material structure topologies in negligible time without any *** performance evaluation results show that the proposed method not only outputs multi-material topologies with clear material boundary but also reduces the calculation cost with high prediction ***,in order to find a more reasonable modeling method for MMTO,this paper studies the characteristics of surrogate modeling as regression task and classification *** the training of 297 models,our findings show that the regression task yields slightly better results than the classification task in most ***,The results indicate that the prediction accuracy is primarily influenced by factors such as the TO problem,material category,and data ***,factors such as the domain size and the material property have minimal impact on the accuracy.

关键词： Multi-material topology optimization convolutional neural networks deep learning finite element analysis

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Underwater Acoustic Signal Noise Reduction Based on a Fully Convolutional Encoder-Decoder Neural Network

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Journal of Ocean University of China 2023年第6期22卷 1487-1496页

作者： SONG Yongqiang CHU Qian LIU Feng WANG Tao SHEN Tongsheng PLA Academy of Military Science Beijing 100089China PLA National innovation institute of defense technology Beijing 100071China Yantai Urban and Rural Construction School Yantai 264000China

Noise reduction analysis of signals is essential for modern underwater acoustic detection *** traditional noise reduction techniques gradually lose efficacy because the target signal is masked by biological and natural noise in the marine *** feature extraction method combining time-frequency spectrograms and deep learning can effectively achieve the separation of noise and target signals.A fully convolutional encoder-decoder neural network(FCEDN)is proposed to address the issue of noise reduc-tion in underwater acoustic *** time-domain waveform map of underwater acoustic signals is converted into a wavelet low-frequency analysis recording spectrogram during the denoising process to preserve as many underwater acoustic signal characteristics as *** FCEDN is built to learn the spectrogram mapping between noise and target signals that can be learned at each time *** transposed convolution transforms are introduced,which can transform the spectrogram features of the signals into listenable audio *** evaluating the systems on the ShipsEar Dataset,the proposed method can increase SNR and SI-SNR by 10.02 and 9.5dB,re-spectively.

关键词： deep learning convolutional encoder-decoder neural network wavelet low-frequency analysis recording spectrogram

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Sol-gel transition effect based on konjac glucomannan thermosensitive hydrogel for photo-assisted uranium extraction

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Science Bulletin 2024年第19期69卷 3042-3054页

作者： Xudong Wu Tong Liu Huimin Li Yizhou He Guolin Yang Wenkun Zhu Tao Chen State Key Laboratory of Environment-friendly Energy Materials School of Life Science and EngineeringSchool of National Defense of Science and TechnologyNational Co-innovation Center for Nuclear Waste Disposal and Environmental SafetySichuan Civil-military Integration InstituteSouthwest University of Science and TechnologyMianyang 621010China College of Science National University of Defense TechnologyChangsha 410073China

Exploiting the intelligent photocatalysts capable of phase separation provides a promising solution to the removal of uranium,which is expected to solve the difficulty in separation and the poor selectivity of traditional photocatalysts in carbonate-containing uranium *** this paper,theγ-FeOOH/konjac glucomannan grafted with phenolic hydroxyl groups/poly-N-isopropylacrylamide(γ-FeOOH/KGM(Ga)/PNIPAM)thermosensitive hydrogel is proposed as the photocatalysts for extracting uranium from carbonate-containing uranium *** dynamic phase transformation is demonstrated to confirm the arbitrary transition ofγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel from a dispersed state with a high specific surface area at low temperatures to a stable aggregated state at high ***,theγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel achieves a remarkably high rate of 92.3%in the removal of uranium from the wastewater containing carbonates and maintains the efficiency of uranium removal from uranium mine wastewater at over 90%.Relying on electron spin resonance and free radical capture experiment,we reveal the adsorption-reduction-nucleation-crystalliza tion mechanism of uranium onγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive ***,this strategy provides a promising solution to treating uranium-contaminated wastewater,showing a massive potential in water purification.

关键词： Carbonate-containing uranium wastewater Konjacglucomannan γ-FeOOH PNIPAM Temperature responsivehydrogel Photo-assisted uraniumextraction

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Multiphysics Numerical Simulation and Geometric Optimization of a Micronozzle for the MEMS Thruster

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Space(Science & technology) 2023年第1期3卷 235-247页

作者： Xingchen Li Haopeng Liang Ruofan Zhang Wen Yao Xiaoqian Chen defense innovation institute Chinese Academy of Military ScienceBeijing 100071China Department of Energy Sciences Lund UniversityLund 22100Sweden College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

This paper reports a numerical research on MEMS(microelectromechanical system)micronozzles through multiphysics coupling simulation along with design optimization based on simulation *** micronozzle,which is a core component of the electrothermal microthruster,features a micron-scale geometry,a 2-dimensional(2D)Laval configuration,a rectangular cross section,and a highly thermal conductive silicon wall due to MEMS *** a result,viscous loss in the flow field and heat transfer to the nozzle wall can strongly influence nozzle performance,namely,thrust force and specific *** accurately understand the flow field inside the micronozzle and how the highly thermal conductive silicon wall interacts with gas flow,a numerical simulation that couples fluid dynamics field and solid heat transfer field is employed in the *** influence of different structural parameters on micronozzle performance is then investigated to set a basis for design *** optimum design of the linear expander micronozzle is obtained through constrained optimization by linear *** further improve micronozzle performance,the bell-shaped expander is *** optimization result shows that the bell-shaped expander is not suitable for micronozzle featuring 2D Laval configuration,and the reason behind the phenomenon is thoroughly discussed.

关键词： optimization shaped viscous

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The 260-W coherent beam combining of two compact fibre amplifier chains

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Chinese Physics B 2011年第11期20卷 255-260页

作者：王小林马阎星周朴何兵薛宇豪刘驰李震肖虎许晓军周军刘泽金赵伊君 College of Optoelectronic Science and Engineering National University of Defense Technology Shanghai institute of Optics and Fine Mechanics

Coherent beam combining of two fibre amplifier chains with a total power of 260 W in a compact system using the stochastic parallel gradient descent （SPGD） algorithm is demonstrated. A 150 MHz linewidth fibre laser is built and introduced for high-power amplification to mitigate stimulated Brillouin scattering （SBS）. Compact high-power amplifier chains are built with low power all-fibre system and high-power bulk free-optics fibre amplifiers. When the total power is about 260 W, active phase-locking of two high-power amplifiers is demonstrated using the SPGD algorithm. In closed-loop, the power in the main lobe increases 1.68 times, the visibility is increased from 0 to 0.62, and the phase residual error is less than λ/10.

关键词： fibre amplifier coherent beam combining stimulated Brillouin scattering stochasticparallel gradient descent algorithm

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Process-controllable modulation of plasmon-induced transparency in terahertz metamaterials

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Chinese Optics Letters 2021年第1期19卷 100-105页

作者： Hao Sun Jie Yang Hengzhu Liu Dan Wu Xin Zheng College of Computer National University of Defense TechnologyChangsha 410073China National innovation institute of defense technology Beijing 100010China Graduate School National University of Defense TechnologyChangsha 410073China

Recently reported plasmon-induced transparency(PIT)in metamaterials endows the optical structures in classical systems with quantum optical *** particular,the nonreconfigurable nature in metamaterials makes multifunctional applications of PIT effects in terahertz communications and optical networks remain a great ***,we present an ultrafast process-selectable modulation of the PIT *** incorporating silicon islands into diatomic metamaterials,the PIT effect is modulated reversely,depending on the vertical and horizontal configurations,with giant modulation depths as high as 129%and 109%.Accompanied by the enormous switching of the transparent window,remarkable slow light effect occurs.

关键词： terahertz metamaterials ultrafast photoswitching plasmon-induced transparency all-optical modulation

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Experimental Evidence of Topological Surface States in Mg3Bi2 Films Grown by Molecular Beam Epitaxy

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Chinese Physics Letters 2019年第11期36卷 65-69页

作者： Tong Zhou Xie-Gang Zhu Mingyu Tong Yun Zhang Xue-Bing Luo Xiangnan Xie Wei Feng Qiuyun Chen Shiyong Tan Zhen-Yu Wang Tian Jiang Yuhua Tang Xin-Chun Lai Xuejun Yang State Key Laboratory of High Performance Computing College of ComputerNational University of Defense TechnologyChangsha 410073 Science and technology on Surface Physics and Chemistry Laboratory Jiangyou 621908 National innovation institute of defense technology Academy of Military Sciences PLA ChinaBeijing 100010 institute of Materials China Academy of Engineering PhysicsMianyang 621700 College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073 Academy of Military Sciences PLA China Beijing 100010 Beijing Academy of Quantum Information Sciences Beijing 100084

Nodal line semimetal(NLS) is a new quantum state hosting one-dimensional closed loops formed by the crossing of two bands. The so-called type-Ⅱ NLS means that these two crossing bands have the same sign in their slopes along the radial direction of the loop, which requires that the crossing bands are either right-tilted or left-tilted at the same time. According to the theoretical prediction, Mg3Bi2 is an ideal candidate for studying the type-Ⅱ NLS by tuning its spin-orbit coupling(SOC). High-quality Mg3 Bi2 films are grown by molecular beam epitaxy(MBE). By in-situ angle resolved photoemission spectroscopy(ARPES), a pair of surface resonance bands around theГ point are clearly seen. This shows that Mg3Bi2 films grown by MBE are Mg(1)-terminated by comparing the ARPES spectra with the first principles calculations results. Moreover, the temperature dependent weak anti-localization effect in Mg3Bi2 films is observed under magneto-transport measurements, which shows clear two-dimensional(2 D) e-e scattering characteristics by fitting with the Hikami–Larkin–Nagaoka model. Therefore, by combining with ARPES, magneto-transport measurements and the first principles calculations, this work proves that Mg3Bi2 is a semimetal with topological surface states. This paves the way for Mg3Bi2 to be used as an ideal material platform to study the exotic features of type-Ⅱ nodal line semimetals and the topological phase transition by tuning its SOC.

关键词： bands topological terminated

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Confidential Image Super-Resolution with Privacy Protection

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Chinese Journal of Electronics 2024年第6期33卷 1447-1457页

作者： Yiran HAN Jianwei LIU Xin DENG Junpeng JING Yanting ZHANG School of Cyber Science and technology Beihang University Beihang University Hangzhou innovation institute China Electronics Standardization institute

Nowadays, people are getting used to upload images to a third party for post-processing, such as image denoising and super-resolution. This may easily lead to the disclosure of the privacy in the confidential images. One possible solution is to encrypt the image before sending it to the third party, the encrypted image can be easily detected by a malicious attacker in the transmission channel. We propose a confidential image super-resolution method named HSR-Net which firstly hide the secret image and then super-resolve it in the hidden domain. The method is composed of three important modules: image hiding module(IHM), image super-resolution module(ISM), and image revealing module(IRM). The IHM aims to encode secret image and hide it into a cover image to generate the stego image. The stego image looks similar to the cover image but contains the information of the secret image. The third party uses the ISM to perform image super-resolution on the stego image. The user can reveal the super-resolved secret image from the stego image. The proposed HSR-Net method has two advantages. It ensures that the third party cannot directly operate on the secret image, thus protecting the user's privacy. Due to the similarity between the stego image and cover image, we can reduce the attacker's suspicion to further improve the image security. The experimental results were tested on DIV2K dataset and Flickr2K dataset. The peak signal-to-noise ratios(PSNR) of IHM, ISM, and IRM are 38.81 dB, 28.91 dB, and 23.51 dB, respectively, which verify that the proposed HSR-Net method is able to achieve image super-resolution and protect user's privacy simultaneouly.

关键词： Privacy Data privacy PSNR Superresolution Cryptography Protection Signal resolution Image denoising

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Robo Cloud: augmenting robotic visions for open environment modeling using Internet knowledge

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Science China(Information Sciences) 2018年第5期61卷 19-34页

作者： Yiying LI Huaimin WANG Bo DING Wei ZHOU College of Computer National University of Defense Technology

Modeling an open environment that contains unpredictable objects is a challenging problem in the field of robotics. In traditional approaches, when a robot encounters an unknown object, a mistake will inevitably be added to the robot's environmental model, severely constraining the robot's autonomy,and possibly leading to disastrous consequences in certain settings. The abundant knowledge accumulated on the Internet has the potential to remedy the uncertainties that result from encountering with unknown objects. However, robotic applications generally pay considerable attention to quality of service(Qo S).For this reason, directly accessing the Internet, which can be unpredictable, is generally not *** Cloud is proposed as a novel approach to environment modeling that takes advantage of the Internet without sacrificing the critical properties of Qo S. Robo Cloud is a "mission cloud–public cloud" layered cloud organization model in which the mission cloud provides Qo S-available environment modeling capability with built-in prior knowledge while the public cloud is the existing services provided by the Internet. The "cloud phase transition" mechanism seeks help from the public cloud only when a request is outside the knowledge of the mission cloud and the Qo S cost is acceptable. We have adopted semantic mapping, a typical robotic environment modeling task, to illustrate and substantiate our approach and key mechanism. Experiments using open 2 D and 3 D datasets with real robots have demonstrated that Robo Cloud is able to augment robotic visions for open environment modeling.

关键词： Internet-augmented environment modeling uncertainty robotic visions semantic mapping robotic software cloud robotics

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Multi-Electron Effects in Attosecond Transient Absorption of CO Molecules

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Chinese Physics Letters 2018年第4期35卷 20-24页

作者： Bin Zhang Jian Zhao Zeng-Xiu Zhao Northwest institute of Nuclear technology Xi'an 710024 Department of Physics College of Science National University of Defense Technology Changsha 410073

Using the fully propagated time-dependent Hartree–Fock method, we identify that both the dynamic core polarization and multiorbital contributions are important in the attosecond transient absorption of CO *** dynamics of core electrons effectively modifies the behaviors of electrons in the highest occupied molecular orbital, resulting in the modulation of intensity and position of the absorption peaks. Depending on the alignment angles, different inner orbitals are identified to contribute, and even dominate the total absorption spectra. As a result, multi-electron fingerprints are encoded in the absorption spectra, which shed light on future applications of attosecond transient absorption in complex systems.

关键词： Multi-Electron Effects in Attosecond Transient Absorption of CO Molecules SAO As CO

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