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IET International Radar Conference (IRC 2023)

作者： Jingpeng Gao Chen Shen Lu Gao Zhiye Jiang College of Information and Communication Engineering Harbin Engineering University Harbin People's Republic of China Beijing Institute of Electronic System Engineering Beijing People's Republic of China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing People's Republic of China

ISBN: (数字)9781837240982

In the study of the multi-UAV penetration mission decision method, the Heterogeneous Agent Soft Actor-Critic algorithm uses the HAML framework and the maximum entropy principle to enable UAVs to have stronger anti-jamming capability and exploration capability. However, it is difficult to accurately evaluate the action value of UAVs and the training stability is poor. To address this issue, this paper proposes a multi-agent based on the state prediction-HASAC (SP-HASAC) jamming decision method. Based on the idea of advantage function decomposition and environmental dynamics model, the state prediction network is designed to extract more abundant spatial information of penetration battlefield and achieve accurate evaluation of the action value of multi-UAV. Combining with the negative domain activation theory, the ReLU function is improved to realize the stable training of multi-UAV. The simulation results show that in the electronic penetration scenario of three UAVs against a single radar, the training convergence time of the proposed improved algorithm is reduced by 22% compared with the original algorithm. Three UAVs penetration to twice the burn-through distance still has more than 70% penetration success rate.

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A Fast Design Method for Ultra Broadband Absorbers Using RC Equivalent Circuit Model

A Fast Design Method for Ultra Broadband Absorbers Using RC ...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Xianglin Kong Lei Zhao Fengjun Wang Shengjun Zhang Yixiang Fu Xiaoyu Pang Xiaochun Liu Xiaopeng Shen School of Information and Control Engineering China University of Mining and Technology Xu Zhou CA China National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing China Key Laboratory of Aeronautical Science and Technology for High Performance Electromagnetic Window Jinan China School of Materials and Physics China University of Mining and Technology Xuzhou China

An accuracy and efficient approach is proposed to fast design ultra-wideband microwave absorbers. The RC equivalent circuit model of absorbers is established according to impedance matching and transmission line theory. The model is suitable for low and high-frequency absorbers composed of multilayer square high impendence surface (HIS) and air layers of impendence matching. Absorbers with different parameters can be fast designed by utilizing the proposed model and genetic algorithm. The reflection coefficient of RC circuit and full-simulation are in good agreement, both of them are lower than -10 dB within 2-18 GHz or 4-50 GHz (fractional bandwidth of 160% or 170.37%), with the total thickness close to the Rozanov limit. An absorber is fabricated and measured to further verify the accuracy of the model. The measured results have a good agreement with the RC circuit model, which indicates the proposed method is an efficient way for fast designing ultra-broadband thin absorbers using double-layer (or multilayer) square HIS.

关键词： Microwave measurement Atmospheric modeling Transmission line measurements Nonhomogeneous media Microwave theory and techniques Microwave circuits Frequency measurement

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Two-mode terms in Wigner transport equation elucidate anomalous thermal transport in amorphous silicon

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Physical Review B 2025年第9期111卷 094206-094206页

作者： Jin Yang Xueyan Zhu Alan J. H. McGaughey Yee Sin Ang Wee-Liat Ong ZJU-UIUC Institute College of Energy Engineering Zhejiang University Jiaxing Haining Zhejiang 314400 China China Academy of Engineering Physics Software Center for High Performance Numerical Simulation Beijing 100088 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China Department of Mechanical Engineering Carnegie Mellon University Pittsburgh Pennsylvania 15213 USA Science Mathematics and Technology Singapore University of Technology and Design 487372 Singapore State Key Laboratory of Clean Energy Utilization Zhejiang University Hangzhou Zhejiang 310027 China

Over the past decades, our understanding of thermal transport in amorphous materials has predominantly relied on the inherently harmonic Allen-Feldman theory, which has been found to be insufficient. In this study, the Wigner transport formalism is adopted to explicitly account for anharmonicity. In studying the thermal transport in amorphous silicon, the results highlight that amorphous materials are not generally computationally equivalent to crystals with disordered primitive cells. A method that leverages the properties of the two-mode terms in the Wigner transport formalism is proposed to predict the bulk thermal conductivity of amorphous materials using finite-size models. In doing so, the need for mode classification schemes required in the Allen-Feldman theory is eliminated, and similarities are discovered between the two-mode terms and the carriers commonly used to describe thermal transport in amorphous materials, i.e., propagons, diffusons, and locons. Two competing trends are identified that shed light on the recently discovered anomalous decrease in the high-temperature thermal conductivity in some amorphous materials.

关键词： Heat transfer

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Design of a Printed Monopole Array Antenna with the Simple Feeding Structure

Design of a Printed Monopole Array Antenna with the Simple F...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Shi Xiaofei Liu Yizhuo Liu Jiaqi Fang Yizhong Gao Zhiwei Wang Lei Song Lizhong Shandong Institute of Space Electronic Technology Yantai China School of Electronics and Information Engineering Harbin Institute of Technology Harbin China School of Information Science and Engineering Harbin Institute of Technology at Weihai Weihai China National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China School of Information Science and Technology Shijiazhuang Tiedao University Shijiazhuang China Shandong Huayu Aerospace Technology Co. Ltd Yantai China

This paper introduces an array antenna by use of printed monopole antennas as element. The designed array antenna consists of two layers of dielectric substrate and a metal reflective ground. The array antenna element adopts trapezoidal printed monopole antenna, and the element is fed by coplanar waveguide (CPW). The array antenna radiator is located on the top of the upper dielectric substrate, and the feeding microstrip power divider network is located on the bottom of the lower dielectric substrate. The antenna element radiator is vertically connected to the microstrip feeding power divider network in a coaxial-like manner. The whole structure of the antenna is simple, and the feeding structure is convenient, which makes it suitable for fabrication and assembly. A printed 4x4 monopole array antenna was designed and the relevant simulated results are provided. The simulation results show that at the 10GHz, the designed array antenna has a gain of approximately 12.73 dB and a return loss of approximately -11.75 dB. The antenna scheme discussed in this paper can provide technical reference for the design of planar printed array antennas.

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Explaining China's climate in 2021

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Advances in Climate Change Research 2022年第6期13卷 769-771页

作者： Ying SUN Qing-Chen CHAO Bo-Tao ZHOU Tian-Jun ZHOU Climate Studies Key Laboratory National Climate CenterChina Meteorological AdministrationBeijing 100081China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044China School of Atmospheric Sciences Nanjing University of Information Science&TechnologyNanjing 210044China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

*** Human-induced climate change,including more frequent and more intense of some type of extreme events,has caused widespread adverse impacts and related losses and damages to natural environment,ecosystems,and human society(IPCC,2022).In the recent decades,the economic losses caused by climate change and its accompanying extreme events have increased in *** becomes necessary to understand the causes of anomalous climate and *** the backdrop of global warming,the year 2021 was very warm in China along with the occurrence of very unusual extreme events(CMA,2022).Documenting and explaining the climate each year,including the anomalous state and the most significant extreme weather and climate events,are important to improve scientific understanding of fast-evolving climate,and to provide the public and policymakers with timely,peer-reviewed,authoritative scientific information.

关键词： China. climate anomalous

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numerical simulation and analysis of lithium plasma during low-pressure DC arc discharge

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Plasma science and technology 2019年第4期21卷 16-21页

作者： Runhui WU Song CHAI Jiaqi LIU Shiyuan CONG Gang MENG National Key Laboratory of Science and Technology on Test Physics&Numerical Mathematics Beijing 100076People's Republic of China School of Physics Dalian University of TechnologyDalian 116024People's Republic of China

Alkali metal DC arc discharge has the characteristics of easy ionization,low power consumption,high plasma temperature and ionization degree,etc,which can be applied in aerospace vehicles in various *** this paper,we calculate the physical property parameters of lithium vapor,one of the major alkali metals,and analyze the discharge characteristics of lithium plasma with the magnetohydrodynamic(MHD)*** discharge effects between constant current and voltage sources are also *** is shown that the lithium plasma of DC arc discharge has relatively high temperature and current *** peak temperature can reach tens of thousands of K,and the current density reaches 6 x 107 A m *** the same rated power,the plasma parameters of the constant voltage source discharge are much higher than those of the constant current source discharge,which can be used as the preferred discharge mode for aerospace applications.

关键词： DC discharge lithium plasma numerical simulation low-pressure arc

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numerical analysis of a linear generalized finite difference scheme for Burgers' equation

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Computers and mathematics with Applications 2025年 193卷 117-131页

作者： Wang, Kai Li, Yubo Wu, Anping Yin, Xiaoxin Liu, Feng Feng, Xinlong College of Mathematics and Systems Science Xinjiang University Urumqi 830017 China Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development Center Sichuan Province Mianyang 621010 China National Key Laboratory of Aerospace Physics in Fluids Sichuan Province Mianyang 621010 China School of Computer Science and Technology Southwest University of Science and Technology Sichuan Province Mianyang 621010 China

In this study, we solved the Burgers' equation using a generalized finite-difference method and constructed a two-layer explicit scheme. The Generalized Finite Difference Method (GFDM) is a meshless collocation method for solving partial differential equations. By using GFDM, it is possible to avoid constructing meshes for simulations. Moreover, due to the property of the moving least-square approximation in GFDM, the resulting matrix system can be formed into a sparse matrix, which makes GFDM suitable for solving large-scale problems. Subsequently, we performed a numerical analysis of the scheme. The maximum norm error estimate of the linear difference scheme was proven, demonstrating second-order convergence in both time and space with appropriate parameter selection. Finally, we verify our conclusions using five numerical examples. The numerical results were consistent with the theoretical analysis, comprehensively validating the excellent performance of the constructed two-layer explicit generalized finite-difference scheme for solving the Burgers' equation. © 2025 Elsevier Ltd

关键词： Burgers' equation Generalized Finite Difference Method Linear meshless numerical scheme

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Constraining the spin-gravity coupling effects to the 10−10-level with dual-species atom interferometers

arXiv

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arXiv 2024年

作者： Gao, Dongfeng Zhou, Lin Wang, Jin Zhan, Mingsheng State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan430071 China Hefei National Laboratory Hefei230088 China Wuhan Institute of Quantum Technology Wuhan430206 China

Spin is one fundamental property of microscopic particles. A lot of theoretical work has postulated the possible coupling between spin and gravitation, which could result in the violation of equivalence principle. In our recent joint mass-and-energy test of the weak equivalence principle with a 10-meter 85Rb-87Rb dual-species atom interferometer, the Eötvös parameters of four 85Rb-87Rb combinations with specific atomic spin states were measured to the 10−10-level (L. Zhou et al., Phys. Rev. A 104, 022822). Here these experimental results are used to constrain the postulated spin-gravity coupling effects. The bounds on the spin-independent and spin-dependent anomalous passive gravitational mass tensors in Lämmerzahl’s model are set to the 10−10-level, which improves existing bounds by three orders of magnitude. The constraints to the spin-independent electron- and proton-gravity coupling parameters in the gravitational standard-model extension are set to the 10−6 GeV-level. Copyright © 2024, The Authors. All rights reserved.

关键词： Atoms

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Adaptive-Correlation Back-Projection Imaging Algorithm for Ground Penetrating Radar in Complex Scenes

Adaptive-Correlation Back-Projection Imaging Algorithm for G...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Qianqi Dai Gao Lu Tao Jiang Key Laboratory of Advanced Marine Communication and Information Technology Ministry of Industry and Information Technology Harbin Engineering University Harbin China National Key Laboratory of Science and Technology on Test Physics and umerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China

The current correlation back-projection algorithm can only deal with the imaging of objects at the same buried depth. However, for objects with different depths and different relative permittivity, the electromagnetic wave echo composition is complicated, there is no strong correlation between the time delays of the reflected echoes, the echo signal in the center of the detection area is used as a reference signal to perform consistent correlation processing, which will cause serious suppression. In this paper, an improved adaptive correlation algorithm was proposed. Firstly, the algorithm of maximum variance between clusters (OSTU) is used to extract the horizontal position and number of buried objects, and then the relevant parameters are adaptively adjusted according to the reflected energy and horizontal position of different targets. Finally, back-projection algorithm imaging is performed. Simulation experiments showed that the algorithm proposed in this paper can effectively improve the imaging effect, improve the detection probability of buried objects, and adapt to the variability of detection scenes.

关键词： Adaptation models Correlation Ground penetrating radar Delay effects Computational modeling Electromagnetic scattering Clustering algorithms

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Correcting Climate Model Sea Surface Temperature Simulations with Generative Adversarial Networks:Climatology,Interannual Variability,and Extremes

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Advances in Atmospheric sciences 2024年第7期41卷 1299-1312页

作者： Ya WANG Gang HUANG Baoxiang PAN Pengfei LIN Niklas BOERS Weichen TAO Yutong CHEN BO LIU Haijie LI State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Earth System Modelling School of Engineering and DesignTechnical University of MunichOttobrunn 85521Germany Potsdam Institute for Climate Impact Research Potsdam 14412Germany Department of Mathematics and Global Systems Institute University of ExeterExeter EX44QEUK CMA Earth System Modeling and Prediction Centre(CEMC) Chinese Academy of Meteorological SciencesBeijing 100081China

Climate models are vital for understanding and projecting global climate change and its associated ***,these models suffer from biases that limit their accuracy in historical simulations and the trustworthiness of future *** these challenges requires addressing internal variability,hindering the direct alignment between model simulations and observations,and thwarting conventional supervised learning ***,we employ an unsupervised Cycle-consistent Generative Adversarial Network(CycleGAN),to correct daily Sea Surface Temperature(SST)simulations from the Community Earth System Model 2(CESM2).Our results reveal that the CycleGAN not only corrects climatological biases but also improves the simulation of major dynamic modes including the El Niño-Southern Oscillation(ENSO)and the Indian Ocean Dipole mode,as well as SST ***,it substantially corrects climatological SST biases,decreasing the globally averaged Root-Mean-Square Error(RMSE)by 58%.Intriguingly,the CycleGAN effectively addresses the well-known excessive westward bias in ENSO SST anomalies,a common issue in climate models that traditional methods,like quantile mapping,struggle to ***,it substantially improves the simulation of SST extremes,raising the pattern correlation coefficient(PCC)from 0.56 to 0.88 and lowering the RMSE from 0.5 to *** enhancement is attributed to better representations of interannual,intraseasonal,and synoptic scales *** study offers a novel approach to correct global SST simulations and underscores its effectiveness across different time scales and primary dynamical modes.

关键词： generative adversarial networks model bias deep learning El Niño-Southern Oscillation marine heatwaves

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