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SSRN 2023年

作者： Wu, Xudong He, YiZhou Li, Huiming Yang, Guolin He, Rong Chen, Tao Zhu, Wenkun State Key Laboratory of Environment-friendly Energy Materials National Co-innovation Center for Nuclear Waste Disposal and Environmental Safety Sichuan Civil-military Integration Institute School of Life Science and Engineering School of National Defense of Science and Technology Southwest University of Science and Technology Mianyang621010 China National Synchrotron Radiation Laboratory Research Center Taiwan

Photo-assisted uranium extraction from carbonate-contained wastewater offers a promising solution to mitigate the strong complexation between carbonate anions and uranyl ions. In our study, we synthesized a novel Konjac glucomannan (KGM)/γ-FeOOH composite photocatalytic hydrogel through in-situ γ-FeOOH formation within a KGM solution. Compared to traditional powdered photocatalysts, the KGM/γ-FeOOH porous hydrogel boasts an abundant porous structure and excellent mechanical properties, ensuring enhanced cyclic recovery stability. The uranium removal rate of KGM/γ-FeOOH porous hydrogel in uranium wastewater without carbonate ions was more than 90 %, and even in the presence of carbonate ions, its uranium removal efficiency remained at 79 %, which was significantly better than that of non-porous KGM/γ-FeOOH hydrogel (30 %). Mechanistic studies showed that the KGM/γ-FeOOH porous hydrogel effectively captured the dissociated uranyl ions through the abundant oxygen-containing functional groups on KGM and γ-FeOOH, and subsequently achieved the conversion of uranium to UO2 with the participation of active species such as electrons (e-). In conclusion, our approach provides a strategy for treating uranium-contaminated wastewater with great potential for water purification applications. © 2023, The Authors. All rights reserved.

关键词： Hydrogels

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Learning to Branch in Combinatorial Optimization with Graph Pointer Networks

arXiv

引用

arXiv 2023年

作者： Wang, Rui Zhou, Zhiming Zhang, Tao Wang, Ling Xu, Xin Liao, Xiangke Li, Kaiwen The College of Systems Engineering National University of Defense Technology Changsha410073 China The Hunan Key Laboratory of Multi-Energy System Intelligent Interconnection Technology HKLMSI2T Changsha410073 China Institute of Automation Chinese Academy of Sciences Beijing100190 China The College of Intelligence Science and Technology National University of Defense Technology Changsha410073 China Department of Automation Tsinghua University Beijing100084 China The College of Computer Science and Technology National University of Defense Technology Changsha410073 China

Branch-and-bound is a typical way to solve combinatorial optimization problems. This paper proposes a graph pointer network model for learning the variable selection policy in the branch-and-bound. We extract the graph features, global features and historical features to represent the solver state. The proposed model, which combines the graph neural network and the pointer mechanism, can effectively map from the solver state to the branching variable decisions. The model is trained to imitate the classic strong branching expert rule by a designed top-k Kullback-Leibler divergence loss function. Experiments on a series of benchmark problems demonstrate that the proposed approach significantly outperforms the widely used expert-designed branching rules. Our approach also outperforms the state-of-the-art machine-learning-based branch-and-bound methods in terms of solving speed and search tree size on all the test instances. In addition, the model can generalize to unseen instances and scale to larger instances. Copyright © 2023, The Authors. All rights reserved.

关键词： Combinatorial optimization

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Research on the Scattering Characteristics of the Van Atta Cube Scatterer

Research on the Scattering Characteristics of the Van Atta C...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Lin Gan Zehao Wu Jianbing Li The State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology National University of Defense Technology Changsha China

In order to realize good omnidirectional backtracking of electromagnetic waves, a Van Atta cube scatterer consists of six identical Van Atta plane arrays is proposed. In this paper, the scattering characteristics in different incident directions are emphatically studied. Simulation results show that the Van Atta cube scatterer has the advantage of omnidirectional scattering, with the effective backtracking angle range exceeding 77% of the whole angle domain.

关键词： Backtracking Interference cancellation Simulation Electromagnetic scattering Computational electromagnetics Optimization Antenna arrays

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Tree-based Search Graph for Approximate Nearest Neighbor Search

arXiv

引用

arXiv 2022年

作者： Fan, Xiaobin Wang, Xiaoping Lu, Kai Xue, Lei Zhao, Jinjing Hunan University Changsha410082 China National University of Defense Technology Changsha410073 China National Key Laboratory of Science and Technology on Information System Security Beijing China

Nearest neighbor search supports important applications in many domains, such as database, machine learning, computer vision. Since the computational cost for accurate search is too high, the community turned to the research of approximate nearest neighbor search (ANNS). Among them, graph-based algorithm is one of the most important branches. Research by Fu et al. shows that the algorithms based on Monotonic Search Network (MSNET), such as NSG and NSSG, have achieved the state-of-the-art search performance in efficiency. The MSNET is dedicated to achieving monotonic search with minimal out-degree of nodes to pursue high efficiency. However, the current MSNET designs did not optimize the probability of the monotonic search, and the lower bound of the probability is only 50%. If they fail in monotonic search stage, they have to suffer tremendous backtracking cost to achieve the required accuracy. This will cause performance problems in search efficiency. To address this problem, we propose (r,p)-MSNET, which achieves guaranteed probability on monotonic search. Due to the high building complexity of a strict (r,p)-MSNET, we propose TBSG, which is an approximation with low complexity. Experiments conducted on four million-scaled datasets show that TBSG yields better or comparable search performance than all recent state-of-the-art algorithms. Our code has been released on Github. Copyright © 2022, The Authors. All rights reserved.

关键词： Graphic methods

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Recognition of Continuous Phase Modulation Signals Based on Synchrosqueezing Wavelet Transform

Recognition of Continuous Phase Modulation Signals Based on ...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Guangxin Ruan Liu Zhao Zheng Liu State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology National University of Defense Technology Changsha China

We present a new algorithm that can solve the problem of recognition of continuous phase modulation (CPM) signals to phase shift keying (PSK) signals. The algorithm uses synchrosqueezing wavelet transform (SWT) to extract the instantaneous frequency (IF) of the signal. On this basis, a recognition characteristic parameter is proposed. This paper verifies the parameter is suitable for PSK and CPM signals with different modulation parameters. Finally, the simulation shows that the algorithm can fully recognize CPM signals to BPSK and QPSK signals when signal-to-noise ratio (snr) is above 6dB. Compared with the existing algorithms, the algorithm proposed in this paper has a higher recognition rate in the low snr environment.

关键词： Phase shift keying Frequency modulation Continuous wavelet transforms Computational modeling Computational electromagnetics Discrete wavelet transforms Binary phase shift keying

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Impact Analysis of Passive Multi- False Targets to Phased Array Radar Resources

Impact Analysis of Passive Multi- False Targets to Phased Ar...

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International Conference on Microwave and Millimeter Wave technology Proceedings

作者： Guo-Qing Hao De-Jun Feng Bi-Qin Cheng Jun-Jie Wang Ling Wang The State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science National University of Defense Technology Changsha China Unit 95861 of PLA Jiuquan China

The phase-switched screen (PSS) can change the reflected echo of the target through a certain control method, thereby generating false targets. The study of material properties and the impact of materials on radar has attracted a lot of attention from the academic community. However, there are few studies on the influence of signal echo changes caused by artificial surface metamaterials on radar resources. In this paper, using PSS to change radar echo information to generate false targets in the Doppler frequency domain. Then the multi-false targets jamming effect on radar resources and multi-target tracking is analyzed. Simulation results show that these targets can consume radar search and tracking resources, generate a large number of temporary trails. This research is beneficial to the application of PSS for interference radar resources.

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Pulse Signal Denoising Method Based on Frequency Domain Wavelet Transform

Pulse Signal Denoising Method Based on Frequency Domain Wave...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Zhao Liu Guangxin Ruan Zheng Liu State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology National University of Defense Technology Changsha China

Bandpass filtering and time-domain wavelet threshold denoising methods do not perform well in pulse signal denoising, which are not effective for Specific Emitter Identification (SEI). Base on this problem, we propose a frequency-domain wavelet threshold denoising method, and improve the threshold estimation method as well as threshold function. Simulation results show that the proposed method is more superior than traditional methods in restoring the envelope and instantaneous frequency of the single-frequency pulse signals, which proves that our method has the potential to improve the accuracy of SEI.

关键词： Wavelet transforms Wavelet domain Filtering Frequency-domain analysis Simulation Noise reduction Estimation

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Large potential of strengthening the land carbon sink in China through anthropogenic interventions

引用

science Bulletin 2024年第16期69卷 2622-2631页

作者： Xu Yue Hao Zhou Yang Cao Hong Liao Xiaofei Lu Zhen Yu Wenping Yuan Zhu Liu Yadong Lei Stephen Sitch Jürgen Knauer Huijun Wang Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science&Technology(NUIST)Nanjing 210044China College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China Jiangsu Nanjing Environmental Monitoring Center Nanjing 210013China Key Laboratory of Agrometeorology of Jiangsu Province Institute of EcologySchool of Applied MeteorologyNUISTNanjing 210044China Institute of Carbon Neutrality Sino-French Institute for Earth System ScienceCollege of Urban and Environmental SciencesPeking UniversityBeijing 100871China Department of Earth System Science Tsinghua UniversityBeijing 100084China State Key Laboratory of Severe Weather and Key Laboratory of Atmospheric Chemistry of CMA Chinese Academy of Meteorological SciencesBeijing 100081China College of Life and Environmental Sciences University of ExeterExeter EX44RJUK Hawkesbury Institute for the Environment Western Sydney UniversityPenrith 2751Australia Key Laboratory of Meteorological Disaster Ministry of EducationJoint International Research Laboratory of Climate and Environment ChangeCollaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNUISTNanjing 210044China

The terrestrial ecosystem in China mitigates 21%-45%of the national contemporary fossil fuel CO_(2) emissions every *** and strengthening the land carbon sink is essential for reaching China’s target of carbon ***,this sink is subject to large uncertainties due to the joint impacts of climate change,air pollution,and human ***,we explore the potential of strengthening land carbon sink in China through anthropogenic interventions,including forestation,ozone reduction,and litter removal,taking advantage of a well-validated dynamic vegetation model and meteorological forcings from 16 climate *** anthropogenic interventions,considering Shared Socioeconomic Pathways(SSP)scenarios,the land sink is projected to be 0.26-0.56 Pg C a^(-1) at 2060,to which climate change contributes 0.06-0.13 Pg C a^(-1) and CO_(2) fertilization contributes 0.08-0.44 Pg C a^(-1) with the stronger effects for higher emission *** anthropogenic interventions,under a close-to-neutral emission scenario(SSP1-2.6),the land sink becomes 0.47-0.57 Pg C a^(-1) at 2060,including the contributions of 0.12 Pg C a^(-1) by conservative forestation,0.07 Pg C a^(-1) by ozone pollution control,and 0.06-0.16 Pg C a^(-1) by 20%litter removal over planted *** sink can mitigate 90%-110% of the residue anthropogenic carbon emissions in 2060,providing a solid foundation for the carbon neutrality in China.

关键词： Carbon sink Forestation Ozone Litter removal

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Periodically-coded ITR Modulation Characteristics of PCM Signal in Radar Radiation Simulation

Periodically-coded ITR Modulation Characteristics of PCM Sig...

引用

International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Tiehua Zhao Qihua Wu Xiaobin Liu Xiaofeng Ai Feng Zhao Shunping Xiao The State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology National University of Defense Technology Changsha China

The overlapping and mutual coupling between transmitting and receiving signals is a knotty problem in radar radiation simulation. Interrupted transmitting and receiving (ITR) modulation can effectively solve this problem caused by limited space of the microwave chamber. In order to further expand the application of ITR modulation method, the characteristics of periodically-coded interrupted modulation signals are analyzed in this paper. Focusing on the modulated pulse coded modulation (PCM) signal, the time-frequency domain characteristics and matched filter output characteristics are studied in detail. Signal simulation experiments are carried out with MATLAB to verify the accuracy of the theoretical analysis.

关键词： Analytical models Time-frequency analysis Matched filters Mutual coupling Focusing Radar Microwave theory and techniques

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Simulation of Nuclear Reactor Accident Scenarios using Physics-Informed Neural Networks and Transfer-Learning

Simulation of Nuclear Reactor Accident Scenarios using Physi...

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Electronic Information Engineering and Computer science (EIECS), 2021 International Conference on

作者： Yang Yu Yufei Xie Wenlin Wang Guohua Wu Haitao Lan Enbo Lin Ping An Zibin Sun Haichuan Zhang Yixian Wu National Key Laboratory of Parallel and Distributed Computing National University of Defense Technology Changsha China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China School of Automation Wuhan University of Technology Wuhan China Sino-German College of Intelligent Manufacturing Shenzhen Technology University Shenzhen China Institute of Automotive Engineers Hubei University of Automotive Technology Shiyan China Nuclear Power Institute of China Chengdu China

ISBN: (数字)9798331531409

ISBN: (纸本)9798331531416

In a Loss of Coolant Accident (LOCA), reactor core temperatures can rise rapidly, leading to potential fuel damage and radioactive material release. This research presents a groundbreaking method that combines the power of Monte Carlo Sampling and Physics-Informed Neural Networks (PINNs) to simulate and effectively address the challenging Loss of Coolant Accidents (LOCA) in nuclear reactors. In the event of a LOCA, reactor core temperatures can soar rapidly, posing a significant threat to fuel integrity and potentially leading to the release of radioactive materials. By leveraging the strengths of both Monte Carlo Sampling and PINNs, this approach aims to provide a comprehensive and accurate simulation framework for assessing and mitigating the consequences of such accidents. The method yields high prediction accuracy (MAE: 0.033, RMSE: 0.098, R2: 0.814) and demonstrates robustness through transfer learning, maintaining strong performance (MAE: 0.064, RMSE: 0.163, R 2 : 0.735).

关键词： Radioactive materials Accuracy Monte Carlo methods Transfer learning Neural networks Robustness Data models Fuels Inductors Accidents

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