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Magnetic and magnetocaloric effect in a stuffed honeycomb polycrystalline antiferromagnet GdInO_(3)

Chinese Physics B 2022年第6期31卷 656-662页

作者： Yao-Dong Wu Wei-Wei Duan Qiu-Yue Li Yong-Liang Qin Zhen-Fa Zi Jin Tang Universities Joint Key Laboratory of Photoelectric Detection Science and Technology in Anhui Province Anhui Province Key Laboratory of Simulation and Design for Electronic Information Systemand School of Physics and Materials EngineeringHefei Normal UniversityHefei 230601China Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field LaboratoryHFIPSAnhuiChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China

The magnetic and magnetocaloric properties were studied in a stuffed honeycomb polycrystalline antiferromagnet GdInO_(3).The onset temperature of antiferromagnetic ordering was observed at~2.1 *** thermal and magnetic hystereses suggest a reversible magnetocaloric effect(MCE)in the GdInO_(3) *** the magnetic field changes of 0 kOe-50 kOe and 0 kOe-70 kOe,the maximum magnetic entropy change values are 9.65 J/kg·K and 18.37 J/kg·K,respectively,near the liquid helium temperature,with the corresponding relative cooling power values of 115.01 J/kg and211.31 J/*** MCE investigation of the polycrystalline GdInO_(3) serves to illuminate more exotic properties in this frustrated stuffed honeycomb magnetic system.

关键词： GdInO_(3) magnetization magnetocaloric effects stuffed honeycomb antiferromagnet

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Research on Multi-Satellite Mission Planning Based on Improved Genetic Algorithm

Research on Multi-Satellite Mission Planning Based on Improv...

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Computer science and Management technology (ICCSMT), International Conference on

作者： Yang Yang Desheng Liu Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing China

For the multi-satellite mission planning problem, a multi-satellite mission planning model is constructed by considering the constraints of satellite’s visibility window to the target, attitude transition, storage and energy consumption, and an improved genetic algorithm is proposed to solve the model. The algorithm adopts the real number coding method to improve the solution efficiency, introduces the adaptive mechanism and the elite retention strategy, which improves the problems that the genetic algorithm is easy to fall into local optimum and converge early. The effectiveness of the improved genetic algorithm for solving multi-star mission planning is verified through simulation case analysis, and it is compared and analyzed with the standard genetic algorithm. The results show that the well genetic algorithm can achieve faster convergence and better planning results, and has better adaptability to large-scale mission planning problems.

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Coherence analysis of laser pulses based on an external cavity circulation 1

Coherence analysis of laser pulses based on an external cavi...

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1st International Conference on Spatial Atmospheric Marine Environmental Optics, SAME 2023

作者： Xu, He Sun, Difeng Li, Jianbing National University of Defense Technology State Key Laboratory of Complex Electromagnetic Environmental Effects on Electronics and Information System College of Electronic Science and Technology Hunan Changsha410073 China Northwest Institute of Nuclear Technology Shaanxi Xi’an710024 China

ISBN: (纸本)9781510666337

By constructing an external circulating cavity to provide sufficient delay that equals a multiple of pulse repetition time, a method with a fixed experimental configuration is proposed to measure the coherence length of both single-frequency and microwave-modulated optical pulses. This method can accurately determine the number of coherent pulses as well as distinguish the coherence states: complete coherence, partial coherence and complete incoherence. In addition, all desired coherence phenomena are obtained by one-time measurement, avoiding other operations like frequent fiber-cutting or devices-reconnection in previous methods. simulation results show that the coherence length of the dual-frequency laser is periodically extended by the reciprocal of the frequency difference, and the random jitter of pulse propagation time would result in obvious measurement errors via perturbing coherence status. © 2023 SPIE.

关键词： Random errors

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Architecture analysis for avionics prognostics and health management system

Architecture analysis for avionics prognostics and health ma...

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2021 CAA Symposium on Fault Detection, Supervision, and Safety for Technical Processes, SAFEPROCESS 2021

作者： Chen, Runfeng Hu, Yang Hou, Yanze Beijing China Science and Technology on Complex Aviation System Simulation Laboratory 9236 Beijing China

ISBN: (纸本)9781665401159

Prognostics and Health Management (PHM) has been researched on for recent years, and extensive studies have been done on hot topics into this field, such as diagnostics, prognostics, and decision making. However, how to evaluate PHM system architecture is still lacking. This is particularly important when designing avionics system equipped with PHM functions. We propose a general, time-variant architecture model that can simulate PHM system. Performance metrics are calculated to quantitatively evaluate the system architecture. This is useful to find differences of architectures in the earlier design stage in engineering. A case study is presented of the use of architecture modelling to show the effectiveness. And future works are discussed. © 2021 IEEE.

关键词： Decision making

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Broadband Wide-Angle Linear-to-Circular Polarization Converter Based on Metal Strips Loaded Metasurface

Broadband Wide-Angle Linear-to-Circular Polarization Convert...

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

作者： Wang, Jingwen Deng, Shasha Chen, Weidong Zhang, Zhongxiang Chen, Chang University of Science and Technology of China School of Information Science and Technology Hefei230031 China Hefei Normal University Key Laboratory of Simulation and Design for Electronic Information System Hefei230601 China

ISBN: (纸本)9781665452366

A transmissive broadband wide-angle linear-to-circular polarization converter based on metal strips loaded metasurface is proposed in this paper. The converter is composed of three metallic layers separated by dielectric substrates and the metal strips printed on each layer keep orthogonal to each other. To further investigate the operating mechanism of the design, equivalent circuit models are presented. Moreover, the converter is verified to be effective in polarization conversion through the full-wave simulation. With the insertion loss less than 2 dB and 3 dB, the simulation 3-dB axial ratio (AR) bandwidth keeps 67% and 76%, respectively. Furthermore, at an increased incident angle of 40°, the device can still maintain an AR bandwidth over 47% at 2 dB insertion loss, which manifests the validity and rationality of the converter design. © 2022 IEEE.

关键词： Strip metal

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Adversarial Example Attack and Defence of Object Recognition: A Survey

Adversarial Example Attack and Defence of Object Recognition...

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2022 IEEE International Conference on Unmanned systems, ICUS 2022

作者： Tan, Wei Zhao, Jiajia Liang, Xinkai Lu, Hanchen Song, Baogang Guan, Hao Science and Technology On Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China Beijing Mechano-Electronic Engineering Institute Beijing China

ISBN: (数字)9781665484565

ISBN: (纸本)9781665484565

Deep learning-based intelligent object recognition algorithm has been widely applied in object detection, auto driving, ect. However, deep neural network is very vulnerable because of its high-dimensional linearization. The object recognition results can be easily mis-leaded through a tiny disturbance in the original image. This kind of sample that adds tiny disturbance to the original image is called adversarial example. The adversarial example attack is a factor that must be considered in the design of robust object recognition algorithm, that is, the need for adversarial defence. An in-depth understanding of adversarial attack can help the model defend successfully. In this survey, an introduction of adversarial attack and defense aiming to object recognition algorithm at the present stage is summarized, and the challenges to be faced and the development trend in the future are pointed out. © 2022 IEEE.

关键词： Object recognition

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A Band Stop Decoupling Structure for Circularly Polarized Antennas With Different Intervals

A Band Stop Decoupling Structure for Circularly Polarized An...

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

作者： Ding, Yuhang Deng, Shasha Chen, Weidong Zhang, Zhongxiang Chen, Chang University of Science and Technology of China School of Information Science and Technology Hefei230031 China Hefei Normal University Key Laboratory of Simulation and Design for Electronic Information System Hefei230601 China

ISBN: (纸本)9781665452366

In this paper, a novel band stop decoupling structure (BSDS) for circularly polarized microstrip antenna array with different intervals to realize mutual coupling reduction is proposed. The BSDS is composed of complementary split-rings resonator (CSRRs) and split-rings resonator (SRRs), where the CSRRs block TM waves by electric resonance and the SRRs block TE waves by magnetic resonance, respectively. The proposed design is verified by the simulation and the results indicate that the isolation enhancement more than 35 dB can be obtained at the center frequency of 3.4 GHz when the center spacing is 0.37 λ0. Futhermore, when the center spacing reduces to 0.26 λ0, the mutual coupling remains below 25 dB. Besides, the BSDS can improve the radiation pattern offset without affecting the gain and the backward radiation of antennas. © 2022 IEEE.

关键词： Magnetic resonance

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Enhancing Geolocation Accuracy of High-Altitude Airborne SAR Through Tropospheric Delay Compensation

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IEEE Transactions on Geoscience and Remote Sensing 2025年 63卷

作者： Xiang, Yaobing Sun, Yuli Lei, Lin Ji, Kefeng Kuang, Gangyao National University of Defense Technology State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology Changsha410073 China

Geolocation is a crucial step in the processing of synthetic aperture radar (SAR) images. High-altitude airborne SAR systems present unique geolocation challenges due to travelling long distances through the troposphere. However, the impact of tropospheric delay on geolocation is often overlooked in existing airborne SAR studies, which can lead to inaccuracies. To address this issue, we propose a new positioning method, the tropospheric delay-compensated range-Doppler (TDC-RD) model. The TDC-RD model leverages reference atmospheric models to estimate and compensate for the tropospheric delay in SAR images. This model effectively mitigates the impact of tropospheric delay in SAR geolocation. To further optimize the TDC-RD model solution, a digital elevation model (DEM)-assisted dual iteration method is proposed. This method iteratively adjusts the target's plane position and elevation in an alternating manner. The effectiveness of the TDC-RD model has been validated through both simulation experiments and actual flight experiments. The results show a significant improvement in geolocation accuracy compared to existing methods, with a maximum reduction of 11.39 m and 24.33% in the mean absolute error (MAE) of SAR geolocation. The TDC-RD model has a great advantage in long-range SAR geolocation. Our research enhances the accuracy and stability of high-altitude airborne SAR geolocation without requiring ground control points. © 2025 IEEE.

关键词： Troposphere

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Exploration of the application of optimisation algorithm using stochastic gradient descent method in satellite resource allocation

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Applied Mathematics and Nonlinear sciences 2024年第1期9卷

作者： Zhao, Demin Xiong, Wei Shi, Jinjing Science and Technology on Complex Electronic System Simulation Laboratory University of Aerospace Engineering Beijing101400 China Dfh Satellite CO. Ltd Beijing100080 China North Automatic Control Technology Institute Shanxi Taiyuan030006 China

With the popularization and development of communication technology, the resource allocation problem of satellites has become a hot research topic. This study proposes a model for satellite resource allocation through the development of a beam mobilization system model and problem modeling. Then, on the basis of the linear stochastic gradient descent method, the classification accuracy of the algorithm is improved by adjusting the algorithm-solving method. Then its weight assignment method is improved to get the improved weighted linear stochastic gradient descent method. Using the optimized weighted linear stochastic gradient descent method to solve the satellite resource allocation problem from the perspective of the original problem, a model based on IWLSGD is designed and tested for performance. Through simulation experiments, the beam allocation service value of the satellite resource allocation model in this paper is 193, which is 4.32% and 3.21% higher than that of LSGD and WLSGD, respectively, and iterative convergence is faster, and its operation time and service value performs the best under different numbers of communication time slots. The system revenue, system access success rate, and system satisfaction under the interference environment between LEO and GEO are maintained at 15208, 0.8~1.0, and 85%, and keep around 7500, 1, and 75% under 5G base station interference. The satellite resource allocation model in this paper can effectively improve the utilization efficiency of communication resources and better adapt to dynamically changing interference scenarios. © 2024 Demin Zhao et al., published by Sciendo.

关键词： Resource allocation

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Measurement-based Path Loss Prediction and Analysis in Water Scenarios

Measurement-based Path Loss Prediction and Analysis in Water...

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2024 IEEE International Conference on Computational Electromagnetics, ICCEM 2024

作者： Li, Hanpeng Chen, Xiaomin Li, Hangang Ma, Jian Ye, Xuchao Song, Lixin Zhang, Taotao Zhong, Weizhi Zhu, Qiuming Nanjing University of Aeronautics and Astronautics College of Electronic and Information Engineering Nanjing211106 China Aviation Key Laboratory of Science and Technology On Aero Electromechanical System Integration Nanjing211106 China State Key Lab. of Complex Electromagnetic Environment Effects On Electronics and Information System Luoyang471003 China

ISBN: (纸本)9798350383317

Unmanned aerial vehicles (UAVs) have enabled the unmanned management of water areas. Path loss (PL) serves as a critical factor that affects the UAV communication quality. In this work, a PL model for UAV channel in water scenarios is proposed, aiming to explore the multidimensional relationship between transceiver distance, carrier frequency, UAV height, and PL by constructing an Artificial Neural Network (ANN). Moreover, channel measurements are conducted in a river area, and the obtained data are analyzed using the proposed ANN model as well as the close-in (CI) model. The analysis results demonstrates that the PL increases initially and then declines as the UAV height increases. The proposed ANN model has higher prediction accuracy than the classic empirical model, and can achieve precise prediction of the PL in water scenarios. © 2024 IEEE.

关键词： Neural networks

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