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arXiv 2025年

作者： Cao, Hanyan Wang, Yijia Pan, Feng Zhang, Pan CAS Key Laboratory for Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing100049 China Centre for Quantum Technologies National University of Singapore 117543 Singapore Science Mathematics and Technology Cluster Singapore University of Technology and Design 8 Somapah Road 487372 Singapore School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced Study UCAS Hangzhou310024 China International Centre for Theoretical Physics Asia-Pacific Hangzhou Beijing China

Computing free energy is a fundamental problem in statistical physics. Recently, two distinct methods have been developed and have demonstrated remarkable success: the tensor-network-based contraction method and the neural-network-based variational method. Tensor networks are accurate, but their application is often limited to low-dimensional systems due to the high computational complexity in high-dimensional systems. The neural network method applies to systems with general topology. However, as a variational method, it is not as accurate as tensor networks. In this work, we propose an integrated approach, tensor-network-based variational autoregressive networks (TNVAN), that leverages the strengths of both tensor networks and neural networks: combining the variational autoregressive neural network’s ability to compute an upper bound on free energy and perform unbiased sampling from the variational distribution with the tensor network’s power to accurately compute the partition function for small sub-systems, resulting in a robust method for precisely estimating free energy. To evaluate the proposed approach, we conducted numerical experiments on spin glass systems with various topologies, including two-dimensional lattices, fully connected graphs, and random graphs. Our numerical results demonstrate the superior accuracy of our method compared to existing approaches. In particular, it effectively handles systems with long-range interactions and leverages GPU efficiency without requiring singular value decomposition, indicating great potential in tackling statistical mechanics problems and simulating high-dimensional complex systems through both tensor networks and neural networks. © 2025, CC BY.

关键词： Statistical mechanics

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Research on dual-polarisation printed dipole antenna for spherical near-field measurements

Research on dual-polarisation printed dipole antenna for sph...

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IET International Radar Conference 2018, IRC 2018

作者： Zheng, Pei Liu, JiaQi Wang, ShangYue Zhang, Ran Fan, Hu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

Here a dual-polarisation printed dipole antenna for spherical near-field measurements is proposed. The printed dipole employs double-layered structure to obtain low cross-polarisation and uses irregular patch to get wide bandwidth. Two such dipoles are cross arranged to form a dual-polarisation dipole antenna. Simulated results show that the bandwidth is over 72% when VSWR is less than 3, the cross-polarisation ratio is better than 30 dB, the port isolation between two dipoles is better than −26 dB, while good radiation performance is also obtained. All the results above prove that the crossed arrangement structure will not affect the performance of the printed dipole, and the strength of mutual coupling between probes can be neglected. © 2019 Institution of Engineering and technology. All rights reserved.

关键词： Dipole antennas

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Research on near-field focusing algorithm of reconfigurable reflect-array

Research on near-field focusing algorithm of reconfigurable ...

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IET International Radar Conference 2018, IRC 2018

作者： Liu, Hong Yan Zheng, Pei Wang, Chao Guo, Lei Zhang, Xin Yu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

In this study, the near-field beam focusing algorithm of reconfigurable reflect array for security imaging application is proposed. The proposed near-field focusing algorithm is based on classic array method, which is usually adopted for far-field pattern calculation. In order to satisfy the near-field imaging application, the imaging distance is added to array method, and the improved formula can calculate the shifting phase of every array element precisely. In addition, due to discrete phase characteristic of reconfigurable reflect array, a phase choice method based on trigonometric function is used in authors' design. Based on the proposed algorithm, the shifting phase of every element is calculated and obtained the simulated beam focusing patterns. Meanwhile, the calculated shifting phase is written to whole array by field-programmable gate array, the near-field beam scanning patterns is measured and the measured results are in good agreement with the simulated ones. © 2019 Institution of Engineering and technology. All rights reserved.

关键词： Field programmable gate arrays (FPGA)

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Application of Graphic Electromagnetic Computing in Electrically Large Scale Composite Target Scattering

Application of Graphic Electromagnetic Computing in Electric...

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2022 International Applied Computational Electromagnetics Society Symposium, ACES-China 2022

作者： Gao, Lu Fang, Ning Wang, Mingliang Liu, Jiaqi Li, Yanan Wu, Runhui Xu, Yinfang National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Beijing China Beihang University Academy of Electronic Information Engineering Beijing China National Key Laboratory of Science and Technology on Test Physics Beijing China

ISBN: (纸本)9781665452366

The radar cross section(RCS) calculation model of electrically large-scale composite target is established by combining graphic electromagnetic computing(GRECO) with high-frequency optical approximation and physical diffraction. Using different illumination modes, the normal vector at each point on the target surface is obtained, and the total scattering field of the target is acquired by the coherent superposition of the scattering field and the diffraction field at each point on the target surface. © 2022 IEEE.

关键词： Radar cross section

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Predicting Electromagnetic Response of Electromagnetic Metasurface using Deep Learning 15

Predicting Electromagnetic Response of Electromagnetic Metas...

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15th International Conference on Signal Processing Systems, ICSPS 2023

作者： Yang, Bingyan Wang, Qiong Mu, Lei School of Electronic Science and Engineering Nanjing University China Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing100076 China

ISBN: (纸本)9781510675056

Digitally coded metasurface(DMS) is a novel class of electromagnetic materials that possess the ability to manipulate electromagnetic waves at scales significantly smaller than the wavelength. They hold great potential for a wide range of applications, including wireless communication, millimeter-wave imaging, data storage, and sensing. However, the conventional full-wave simulation methods currently employed often require precise geometric modeling, grid planning, and consideration of complex physical models such as material parameters and boundary conditions. These time-consuming and costly approaches face significant challenges in large-scale electromagnetic response studies. Therefore, there is an urgent need to explore more efficient and cost-effective methods to address these issues. In this paper, we propose a deep learning-based approach for predicting the electromagnetic response of individual units in a DMS. We construct a convolutional neural network (CNN) model that can accurately and real-time predict the electromagnetic response based on the input coding pattern. To train and validate the model, we utilize a substantial amount of electromagnetic simulation data and incorporate amplitude constraints into the loss function for model optimization. A way to abandon the dual network structure and achieve simultaneous prediction of dual parameters with smaller computational requirements. Experimental results demonstrate that our model achieves highly accurate predictions of both amplitude and phase responses of DMS, surpassing traditional numerical methods in terms of efficiency and scalability. The proposed deep learning approach offers a promising solution for efficient and low-cost prediction of electromagnetic responses in DMS. © 2024 SPIE.

关键词： Neural network models

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Unmanned aerial vehicle infrared detector simulation modelling and performance analysis

Unmanned aerial vehicle infrared detector simulation modelli...

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2017 IASTED International Conference on Modelling, Identification and Control, MIC 2017

作者： Liu, Fang Liu, Xin Liu, Jiaqi National Key Laboratory of Science and Technology On Test Physics and Numerical Mathematics Nandahongmen Road No.1 Beijing China

ISBN: (纸本)9780889869882

An observation model of unmanned aerial vehicle(UAV) infrared detector is developed. The visibility criterion is derived via geometric relationships between the infrared detector, target and earth, the constraint of the detector's frame angle, and the detection range of infrared detector. Because of the infrared sensor can only obtain the angular information of the target, so it is impossible for one detector to locate position of the target. The position of the target is obtained by two or more detectors. The least square method based multi-sensor target tracking method is introduced. It is important to set a filter before using the tracking data as there are observation errors caused by UAV position error, UAV attitude error, sensor pointing error and sensor image plane position error. The extend Kalman Filter (EKF) algorithm is used to smooth the tracking signals. Finally, two UAV infrared detectors observing a low-orbit target is simulated for their observation performance. The result shows that the infrared detectors can observe the target within the scope of the detection range. When the target flies off the top of the UAV, the detectors can't observe it because of the constraint of the frame angle. The observation error is reduced substantially after the EKF is used.

关键词： Infrared detectors

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The propagation characteristic of the QPSK signals in reentry plasmas 67

The propagation characteristic of the QPSK signals in reentr...

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67th International Astronautical Congress, IAC 2016

作者： Wu, Runhui Liu, Jiaqi Liu, Xin Ren, Aimin Zhang, Shengjun Meng, Gang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical China Academy of Launch Vehicle Technology No 1 Nan Da Hong Men Road Beijing China

A spacecraft entering the Earth's atmosphere is enveloped by a plasma layer or sheath due to shock heating of the surrounding air and ablation of the heat shield material, and the plasma sheath may strongly effect the communication between the vehicles and receiver systems. In order to obtain the influence of communication system which is produced by reentry plasmas, a mechanism of QPSK signals through reentry plasmas which surround vehicles travelling at hypersonic velocities is proposed in this paper, and the simulation model of the QPSK signals propagation in plasma sheath is described. Then the energy attenuation and phase variable of QPSK signals which are transmitted by reentry plasmas are computed. The analysis results are shown that the QPSK signals would be shielded thoroughly if the plasma frequency is bigger than carrier frequency, and when the QPSK signals can propagate in reentry plasmas, the bit error probability (BEP) of communication systems would be improved by reentry plasmas which are ability to absorb the signals energy and vary signals phase. The simulation and analysis technique can also be used to calculate many other communication models such as FSK and ASK. Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved.

关键词： Bit error rate

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Study on Polarization em Wave's Transmission Characteristics in Chaff Cloud Based on Oguchi Method 5

Study on Polarization em Wave's Transmission Characteristics...

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5th IEEE International Conference on Computational Electromagnetics, ICCEM 2019

作者： Yang, Kunlong Li, Jianbing Liu, Xin College of Electronic Science National University of Defense Technology Changsha China National Key Laboratory of Science and Technology on Test Physics Numerical Mathematical Beijing Institute of Space Long March Vehicle Beijing China

ISBN: (纸本)9781538671115

The Oguchi method is an important tool for characterizing the transmission characteristics of polarized electromagnetic waves in precipitation. In this paper, the forward scattering matrix of chaff is calculated for the special random medium of chaff cloud. Then the transmission characteristics of polarized electromagnetic wave, including attenuation, (specific) differential phase, are studied by using Oguchi method. The obtained characteristics are consistent with the physical laws, and the feasibility of the Oguchi method in chaff characteristic analysis is preliminarily verified. © 2019 IEEE.

关键词： Forward scattering

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An Experimental Study on the Object Shielding Performance of Discrete Metal Wire Array

An Experimental Study on the Object Shielding Performance of...

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2018 IEEE International Conference on Computational Electromagnetics, ICCEM 2018

作者： Wang, Weidong Liu, Xin Wang, Mingliang Liu, Jiaqi Meng, Gang Gao, Zhiyong Mu, Lei Ai, Xia Zhang, Shengjun Li, Jianbing Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics Numerical Mathematical Beijing China College of Electronic Science National University of Defense Technology Changsha China

ISBN: (纸本)9781538612415

In this paper, a method of shielding the object behind a discrete metal wire array is proposed and verified by anechoic chamber experiments. Results show that if the metal wire array is dense enough (cell size is smaller than half of the wavelength), the object behind it can be effectually shielded by the discrete metal wire array. The principle can be applied to electromagnetic camouflage and protection. © 2018 IEEE.

关键词： Electromagnetic shielding

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Research on influence of special-shaped honeycomb radar absorbing structure for wide-band absorbing design

Research on influence of special-shaped honeycomb radar abso...

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IET International Radar Conference 2018, IRC 2018

作者： Wang, Ming-Liang Liu, Jia-Qi Xin, Liu Zhao, Xin-Ying Zhang, Sheng-Jun Lei, Mu Xia, Ai Guobin, Wan Wang, Wei-Dong Zhao, Ju-Yan National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical Beijing100076 China Northwestern Polytechnical University Xi'an710072 China

To realise wide-band stealth of radar absorbing material, a special-shaped honeycomb radar absorbing structure within nested cone-shaped scattering configuration is designed. Based on the HS theory and the impedance matching design, the rule about the influence of the geometry parameter and electromagnetic parameter on the absorbing performance is analysed. In addition, the reflectivity performance is analysed on the condition of oblique incidence angles. By optimising the geometry parameters of the special-shaped honeycomb structure and designing the multilayer composite structure based on impedance matching theory, the results indicate that the two absorbing peaks can be formed for the special-shaped honeycomb radar absorbing structure, and the reflectivity is improved for both the vertical and oblique incidence angles. © 2019 Institution of Engineering and technology. All rights reserved.

关键词： Reflection

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