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2024 Photonics and Electromagnetics Research Symposium, PIERS 2024

作者： Lu, Dongwei Ma, Jiazhi National University of Defense Technology State Key Lab. of Complex Electromagnetic Environment Effects on Electronics and Information System China

ISBN: (纸本)9798350375909

The target detection ability of radar in environments with interference or clutter can be further improved by the adaptive beamforming method. However, most existing research results only address the receiving beam, and few research results concern transmitting beam control. Moreover, the typical phase-only methods only consider spatial beamforming, which means that the polarization state cannot be controlled. This paper proposes a novel phase-only beamforming method based on a polarimetric phased array that can control the polarization state of the main lobe to avoid receiving main lobe or sidelobe interference signals. © 2024 IEEE.

关键词： Beamforming

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Broadband Optical Nonlinearities and Ultrafast Carrier Dynamics of GO-CuS Hybrid Film

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Journal of Lightwave technology 2025年第11期43卷 5381-5389页

作者： Zhang, Xuefeng Bai, Xuli Liu, Xiaofei Wang, Dan Han, Hong Xiao, Zhengguo Zhang, Jianguo Nie, Zhongquan Taiyuan University of Technology College of Materials Science and Engineering Institute of New Carbon Materials Taiyuan030024 China Taiyuan University of Technology Key Lab of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province College of Electronic Information and Optical Engineering Taiyuan030024 China Taiyuan Institute of Technology Department of Science Taiyuan030008 China Tongren University Department of Physics and Electronic Engineering Tongren China National University of Defense Technology College of Advanced Interdisciplinary Studies Changsha410073 China

We report the broadband optical nonlinearities and ultrafast carrier dynamics of GO doped with CuS nanoparticles (GO-CuS) following the femtosecond pulse lasers. Both the pure GO and GO-CuS hybrid films are first synthesized by the vacuum filter deposition method and their optical nonlinearities are then examined in the wide wavelength range (400 nm-1064 nm) based on the femtosecond Z-scan technique. The results reveal that, compared to the pristine GO, the introduction of CuS not only makes the GO-CuS hybrid film switched from saturated absorption to reverse saturated absorption possible, but also achieves strong broadband optical nonlinear absorption responses and optical limiting effects. It is demonstrated that the strongest nonlinear absorption coefficient (∼3.6×10-7 m/W) appears at 400 nm excitation, which is dozens of times larger than that under the illumination of 1064 nm. By leveraging the femtosecond pump-probe technique, we further study the ultrafast carrier dynamics of the GO-CuS hybrid film carrying the fast and slow relaxation processes. Moreover, the physical mechanisms behind these excellent nonlinear optical responses are elucidated. The findings presented here indicate that the GO-CuS hybrid film can be regarded as a potential promising candidate in various ultrafast photonics devices. © 1983-2012 IEEE.

关键词： Femtosecond lasers

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A Radar Emitter Fingerprint Feature Resistant to Receiver Distortion 5

A Radar Emitter Fingerprint Feature Resistant to Receiver Di...

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5th IEEE Advanced information Management, Communicates, Electronic and Automation control Conference, IMCEC 2022

作者： Liu, Zhao Liu, Zheng Ruan, Guangxin National University of Defense Technology State Key Lab. of Complex Electromagnetic Environment Effects on Electronics and Information System Changsha China

ISBN: (纸本)9781665479677

In radar specific emitter identification, the non-cooperative receiver itself has fingerprint features similar to the emitter, and the fingerprint features extracted at the receiver are coupled of the two, which limited cross-receiver radar specific emitter identification. To solve this problem, a new fingerprint feature is constructed in this paper, which takes the absolute value of the forward quotient of the neighboring points of the pulse signal spectrum as the emitter feature, weakens the receiver distortion interference by improving the frequency resolution and can be quickly extracted by the Chirp-Z transform. Simulation experiments show that the proposed features can effectively overcome the fingerprint feature shift caused by receiver distortion, have good intra-class aggregation and inter-class differentiability, and achieve higher recognition accuracy than traditional features under the same conditions, proving that the proposed features has important reference value for the practical application of cross-receiver radar specific emitter identification. © 2022 IEEE.

关键词： Radar receivers

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On the Gaussian Filtering for Nonlinear Dynamic systems Using Variational Inference 27

On the Gaussian Filtering for Nonlinear Dynamic Systems Usin...

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27th International Conference on information Fusion, FUSION 2024

作者： Liu, Yi Li, Xi Yang, Le Mihaylova, Lyudmila Li, Ji University of Canterbury Department of Electrical and Computer Engineering Christchurch New Zealand National University of Defense Technology State Key Lab of Complex Electromagnetic Environment Effects on Electronics and Information Systems Changsha China University of Sheffield Department of Automatic Control and System Engineering Sheffield United Kingdom Locaris Electronic Technology Co. Ltd Zhengzhou China

ISBN: (纸本)9781737749769

This paper introduces a new variational Gaussian filtering approach for estimating the state of a nonlinear dynamic system. We first assume that the predictive distribution of the state is Gaussian and derive an iterative method for updating the state posterior in the natural parameter space through KullbackLeibler divergence minimization. The obtained update rule is the same as that of the conjugate-computation variational inference technique in Bayesian learning. The derivation here is simpler and more insightful. We then impose a Wishart prior on the inverse of the state prediction covariance to take into account the impact of approximating the state predictive distribution using a Gaussian density on the state posterior estimation. The prediction covariance is identified jointly with the state using variational inference and the established state posterior update rule to achieve the desired Gaussian filtering. Simulation study examines the performance of the proposed filtering framework in target tracking based on bearing and range measurements. © 2024 ISIF.

关键词： Wiener filtering

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Impact Analysis of Passive Multi- False Targets to Phased Array Radar Resources 15

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

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15th International Conference on Microwave and Millimeter Wave technology, ICMMT 2023

作者： Hao, Guo-Qing Feng, De-Jun Cheng, Bi-Qin Wang, Jun-Jie Wang, Ling National University of Defense Technology The State Key Lab. of Complex Electromagnetic Environ. Effects on Electronics and Information System College of Electronic Science Changsha410073 China Unit 95861 of Pla Jiuquan735000 China

ISBN: (纸本)9798350338874

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. © 2023 IEEE.

关键词： Target tracking

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On the Approximation of the Quotient of Two Gaussian Densities for Multiple-Model Smoothing 26

On the Approximation of the Quotient of Two Gaussian Densiti...

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26th International Conference on information Fusion, FUSION 2023

作者： Liu, Yi Li, Xi Yang, Le Mihaylova, Lyudmila Xue, Yanbo University of Canterbury Department of Electrical and Computer Engineering Christchurch New Zealand National University of Defense Technology State Key Lab of Complex Electromagnetic Environment Effects on Electronics and Information Systems Changsha China University of Sheffield Department of Automatic Control and System Engineering Sheffield United Kingdom Career Science Lab Beijing China

ISBN: (纸本)9798890344854

The quotient of two multivariate Gaussian densities can be written as an unnormalized Gaussian density, which has been applied in some recently developed multiple-model fixed-interval smoothing algorithms. However, this expression is invalid if instead of being positive definite, the covariance of the unnormalized Gaussian density is indefinite (i.e., it has both positive and negative eigenvalues) or undefined (i.e., computing it requires inverting a singular matrix). This paper considers approximating the quotient of two Gaussian densities in this case using two different approaches to mitigate the caused numerical problems. The first approach directly replaces the indefinite covariance of the unnormalized Gaussian density with a positive definite matrix nearest to it. The second approach computes the approximation through solving, using the natural gradient, an optimization problem with a Kullback-Leibler divergence-based cost function. This paper illustrates the application of the theoretical results by incorporating them into an existing smoothing method for jump Markov systems and utilizing the obtained smoothers to track a maneuvering target. © 2023 International Society of information Fusion.

关键词： Cost functions

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On the Gaussian Filtering for Nonlinear Dynamic systems Using Variational Inference

On the Gaussian Filtering for Nonlinear Dynamic Systems Usin...

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International Conference on information Fusion

作者： Yi Liu Xi Li Le Yang Lyudmila Mihaylova Ji Li Department of Electrical and Computer Engineering University of Canterbury Christchurch NZ State Key Lab of Complex Electromagnetic Environment Effects on Electronics and Information Systems National University of Defense Technology Changsha China Department of Automatic Control and System Engineering University of Sheffield Sheffield UK Locaris Electronic Technology Co. Ltd Zhengzhou China

ISBN: (数字)9781737749769

ISBN: (纸本)9798350371420

关键词： Target tracking Smoothing methods Filtering Estimation Filtering algorithms Prediction algorithms Minimization Nonlinear dynamical systems Bayes methods Iterative methods

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On the Approximation of the Quotient of Two Gaussian Densities for Multiple-Model Smoothing

On the Approximation of the Quotient of Two Gaussian Densiti...

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International Conference on information Fusion

作者： Yi Liu Xi Li Le Yang Lyudmila Mihaylova Yanbo Xue Department of Electrical and Computer Engineering University of Canterbury Christchurch NZ State Key Lab of Complex Electromagnetic Environment Effects on Electronics and Information Systems National University of Defense Technology Changsha China Department of Automatic Control and System Engineering University of Sheffield Sheffield UK Career Science Lab Beijing China

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Design of A High Performance Monobit DFT Based on FPGA and 1-Bit Samplers 7

Design of A High Performance Monobit DFT Based on FPGA and 1...

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7th International Conference on information Science and control Engineering, ICISCE 2020

作者： Ji, Pengfei Lv, Huan Shi, Qingzhan Yuan, Naichang National University of Defense Technology State Key Lab. of Complex Electromagnetic Environment Effects on Electronics and Information System Changsha China

ISBN: (纸本)9781728164069

This paper proposes a new method of calculating Discrete Fourier Transform (DFT) for 1-bit signals sampled by 1-bit samplers based on Field Programmable Gate Array (FPGA), which can be high-efficiency and very fast under the proper conditions. A processing system for implementing the 256-point monobit DFT with the proposed method is designed in this paper. In this system, a constant iteration architecture, in which none multipliers are used, is devised to implement pipeline DFT calculation efficiently. The simulation results and theoretical analysis show that this designed processor can accurately work out the amplitude response and phase response of 1-bit signals faster, compared with radix-2 FFT, while the consumption of the processor is less. Especially, our design can process the monobit DFT with larger size if the sampling rate is determined, while do not have to consume more time for calculation, which means that the resolution and sensitivity of the proposed monobit DFT processor can be quite good. © 2020 IEEE.

关键词： Discrete Fourier transforms

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Hexagonally ordered microbowl arrays decorated with ultrathin CuInS_(2) nanosheets for enhanced photoelectrochemical performance

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Journal of Energy Chemistry 2020年第12期29卷 134-142页

作者： Ming Li Le Chen Yanjie Su Huan Yin Kexiang Hu State Key Laboratory of Transducer Technology Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China School of Electronic Engineering and Automation Guilin University of Electronic TechnologyKey Laboratory of Optoelectronic Information Processing of Guangxi Colleges and Uniy/ersitiesGuilin 541004GuangxiChina Key Laboratory for Thin Film and Microfabrication of the Ministry of Education Department of Micro/Nano ElectronicsSchool of ElectronicsInformation and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China National and Local Joint Engineering Laboratory of Internet Technology on Mine School of Information and Control EngineeringChina University of Mining and TechnologyXuzhou 221008JiangsuChina School of Physics and Telecommunication Engineering Guangxi Colleges and Universities Key Lab of Complex System Optimization and Big Data ProcessingYulin Normal UniversityYulin 537400GuangxiChina

This paper demonstrates the design and fabrication of three-dimensional(3 D) hexagonally ordered microbowl arrays(MBAs) decorated with Cu In S2 nanosheets for enhanced photoelectrochemical(PEC) performance. The 3 D MBAs are fabricated by a micro-fabrication technique. The ultrathin CuInS2 nanosheets are grown on the 3 D electrodes by solvothermal transformation of Cu film. The photocurrent density of 3 D photocathode(CuInS2@MBAs) is about two times higher than that of the planar counterpart(CuInS2@Planar). The improved PEC performance can be ascribed to the elevated light trapping ability and the increased surface area for loading photocatalysts. In addition, CdS quantum dots as cocatalysts are modified onto the Cu In S2 nanosheets to further enhance the PEC activity because the formed p-n heterojunction can accelerate the separation of photogenerated carriers. As a result, the 3 D photocathode of CuInS2/CdS@MBAs shows an optimal incident photon to current efficiency of 10% at the wavelength of400 nm. It is believed that this work can be generalized to design other hierarchical 3 D photoelectrodes for improved solar water splitting.

关键词： Microbowl array CuInS_(2) Nanosheet Photocathode Photoelectrochemical performance

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