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2022 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio science Meeting, AP-S/URSI 2022

作者： Liu, Ganyu Zhu, Hailiang Wang, Kai Qiu, Yuwei Mou, Jinchao Zheng, Pei Wei, Gao Northwestern Polytechnical University Xi'an710129 China The Beijing Research Institute of Telemetry Beijing100094 China The National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

ISBN: (数字)9781665496582

ISBN: (纸本)9781665496582

In this paper, multiagent genetic algorithm (MAGA) is firstly applied to tackle the synthesis of conformal sparse array, a constrained multi-objective optimization problem. Moreover, a model considered low peak sidelobe level (PSLL) is given for conformal sparse array synthesis. For the antenna array deployed on a quadric surface, the PSLL can be reduced by obtaining the optimal antenna element arrangement. An example of 256-element array synthesis with a 56% sparse rate proves MAGA as an effective optimization tool for conformal sparse arrays in low computational cost. © 2022 IEEE.

关键词： Genetic algorithms

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A method for feature extraction based on SVD and machine learning 2

A method for feature extraction based on SVD and machine lea...

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2019 2nd International Conference on Advanced Materials, Intelligent Manufacturing and Automation, AMIMA 2019

作者： Mao, Wei Huang, Shuxian Liu, Xin Liu, Hongyan Liu, Jiaqi Shu, Yi National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics 100076 China Beijing Institute of Precision Mechatronics and Controls 100076 China Beijing Institute of Long March Vehicle 100076 China

By studying the shortcomings of feature, which extracted from Radar-Cross Section(RCS),using mathematical and statistical method, using the idea of extracting abstract features in image recognition and speech recognition by artificial intelligence for reference[2][3]. This paper explores the possibility of extracting abstract features of target's RCS sequence, and proposes an abstract feature extraction method of RCS sequence based on singular value decomposition(SVD) feature decomposition. Because of the poor interpretability of abstract features, four different machine learning algorithms are used to classify the extracted Abstract features. The experimental results show that the machine learning algorithm can classify different types of spatial objects with high accuracy, which shows that the RCS features of different spatial objects can be characterized by abstract features. © Published under licence by IOP Publishing Ltd.

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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Potential Predictability of Sea Surface Temperature in a Coupled Ocean-Atmosphere GCM

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Advances in Atmospheric sciences 2010年第4期27卷 921-936页

作者：严厉王盘兴俞永强李立娟王斌 Institute of Atmospheric Sciences Nanjing University of Information Science & Technology National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences

Using the Flexible Global Ocean-Atmosphere-Land System model （FGOALS） version g1.11, a group of seasonal hindcasting experiments were carried out. In order to investigate the potential predictability of sea surface temperature （SST）, singular value decomposition （SVD） analyses were applied to extract dominant coupled modes between observed and predicated SST from the hindcasting experiments in this study. The fields discussed are sea surface temperature anomalies over the tropical Pacific basin （20~0S-20~0N, 120~0E- 80~0W）, respectively starting in four seasons from 1982 to 2005. On the basis of SVD analysis, the simulated pattern was replaced with the corresponding observed pattern to reconstruct SST anomaly fields to improve the ability of the simulation. The predictive skill, anomaly correlation coefficients （ACC）, after systematic error correction using the first five modes was regarded as potential predictability. Results showed that： 1） the statistical postprocessing approach was effective for systematic error correction; 2） model error sources mainly arose from mode 2 extracted from the SVD analysis-that is, during the transition phase of ENSO, the model encountered the spring predictability barrier; and 3） potential predictability （upper limits of predictability） could be high over most of the tropical Pacific basin, including the tropical western Pacific and an extra 10-degrees region of the mid and eastern Pacific.

关键词： coupled GCM hindcasting experiments SST singular value decomposition potential pre-dictability

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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 Absorptive/Transmissive Frequency Selective Surface with Wide Transmission Band and Low Insertion Loss

An Absorptive/Transmissive Frequency Selective Surface with ...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Hang Song Jiaqi Liu Shengjun Zhang National Key Laboratory of Science & Technology on Test Physics and Numerical Mathematics Beijing China

The Absorptive/transmissive Frequency Selective Surface (ATFSS) is a multi-layer composite periodic structure with out-of-band absorption and in-band transmission characteristics, usually composed of a lossy resistive sheet (RS) and a lossless bandpass FSS. In this paper, an equivalent circuit method based on transmission line theory was used to design the ATFSS with idea of higher frequencies for transmission and lower frequencies for absorption, as well as the impedance conditions for satisfying wave transmission and absorption. Furthermore, the S-parameters was fitted, which verifies the design concept. Finally, the simulation was performed with numerical method. It is shown from the simulation that the broadband absorption of the ATFSS ranges from 2.00 GHz to 6.29 GHz, and the broadband transmission ranges from 8.46 GHz to 11.32 GHz with an insertion loss of less than 1 dB.

关键词： Frequency selective surfaces Absorption Insertion loss Power system stability Propagation losses Stability analysis Broadband communication

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A novel GCV-based criterion for parametric PSF estimation

A novel GCV-based criterion for parametric PSF estimation

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International Conference on Signal Processing Proceedings (ICSP)

作者： Feng Xue Jiaqi Liu Zhifeng Li Gang Meng National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (纸本)9781479921898

We propose a generalized cross validation (GCV) as a novel criterion for estimating a point spread function (PSF) from the degraded image only. The PSF is obtained by minimizing this new objective functional over a family of Wiener processings. Based on this estimated PSF, we then perform deconvolution using our recently developed SURE-LET algorithm. The GCV-based criterion is exemplified with a number of parametric PSF, involving a scaling factor that controls the blur size. A typical example of such parametrization is the Gaussian kernel. The experimental results demonstrate that the GCV minimization yields highly accurate estimates of the PSF parameters, which also result in a negligible loss of visual quality, compared to that obtained with the exact PSF. The highly competitive results outline the great potential of developing more powerful blind deconvolution algorithms based on this criterion.

关键词： Optical filters Abstracts Estimation Fluorescence Noise reduction Integrated optics Optical imaging

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Semantic Segmentation Algorithm of Street View Image Via Deep Learning

Semantic Segmentation Algorithm of Street View Image Via Dee...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Zihui Zhu Wenlin Cai Jianhua Li Feng Xue Lu Gao Jiaqi Liu National Key Laboratory Science and Technology on Test Physics and Numerical Mathematics Beijing China

Real-time semantic segmentation of street view images can be used as a visual aid system during autonomous driving. This paper proposes a multi-branch cross-layer fusion network (MCFNet). The model uses a multi-branch network to extract features, fuses the features of different stages of multiple branches for prediction, and uses a lightweight depthwise separable convolution to reduce the amount of computation. We use the Cityscapes dataset to train and evaluate the algorithm and get 61.6% mIoU and 115.3 fps.

关键词： Cross layer design Visualization Convolution Semantic segmentation Roads Semantics Feature extraction

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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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Polar Coordinate Lattice Boltzmann Kinetic Modeling of Detonation Phenomena

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Communications in Theoretical physics 2014年第11期61卷 737-748页

作者：林传栋许爱国张广财李英俊 State Key Laboratory for GeoM echanics and Deep Underground Engineering China University of Mining and Technology National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Center for Applied Physics and Technology MOE Key Center for High Energy Density Physics Simulations College of Engineering Peking University State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology State Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences

A novel polar coordinate lattice Boltzmann kinetic model for detonation phenomena is presented and applied to investigate typical implosion and explosion processes. In this model, the change of discrete distribution function due to local chemical reaction is dynamically coupled into the modified lattice Boltzmann equation which could recover the Navier–Stokes equations, including contribution of chemical reaction, via the Chapman–Enskog *** the numerical investigations, the main focuses are the nonequilibrium behaviors in these processes. The system at the disc center is always in its thermodynamic equilibrium in the highly symmetric case. The internal kinetic energies in different degrees of freedom around the detonation front do not coincide. The dependence of the reaction rate on the pressure, influences of the shock strength and reaction rate on the departure amplitude of the system from its local thermodynamic equilibrium are probed.

关键词： lattice Boltzmann method detonation wave nonequilibrium behavior polar coordinate

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