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IEEE International Conference on Computational Electromagnetics (ICCEM)

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

ISBN: (数字)9798350383317

ISBN: (纸本)9798350383324

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.

关键词： Analytical models Accuracy Computational modeling Artificial neural networks Predictive models Autonomous aerial vehicles Data models

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Large Eddy simulation of Flow and Heat Transfer Performance in Periodically Inward Corrugated Tubes

SSRN

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SSRN 2023年

作者： Zhong, Yuzhou Song, Yueheng Zhao, Lei Mi, Fei Zhao, Jingquan Zhu, Xiaowei School of Aeronautic Science and Engineering Beihang University Beijing100191 China Science & Technology on Complex Aviation System Simulation Laboratory Beijing100070 China Co. Ltd. Henan453049 China

Corrugated tubes are extensively unitized in enhancing heat transfer within tubular heat exchange devices. The efficiency of these corrugated tubes is closely linked to the geometric characteristics of the surface corrugations. In this study, we conducted an extensive series of Large Eddy simulations on a representative type of enhanced tube featuring periodic inward corrugations (PIC). Our goal was to compile a comprehensive and precise dataset of the thermal and hydraulic properties specific to this design. The key design parameters that define the corrugated patterns are corrugation height, corrugation width, and the length of the straight section. We systematically explored these parameters to understand their impact on heat transfer and fluid dynamics. Among these parameters, corrugation height has been identified as the most influential factor affecting flow and heat transfer properties. As the corrugation height varies from 1/8D to 3/8D, we observed a substantial increase in the friction factor and Nusselt number by a factor of 209 and 5, respectively, at Re = 1000;while the critical Reynolds number decreased roughly from 800 to 100. These findings underscore the significant role of corrugation height in shaping the flow and heat transfer performance of PIC tubes. The other two parameters, corrugation width and straight section length, were also found to be crucial in determining the overall heat transfer coefficient and pressure drop. The results of our study suggest that when utilizing this type of corrugated tubes, careful consideration is required to strike an optimal balance between heat transfer efficiency and pressure loss. The large-sets LES results presented in this paper can serve as valuable inputs for optimizing the design of PIC tubes. © 2023, The Authors. All rights reserved.

关键词： Large eddy simulation

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Waveform design for pulse radar based on interrupted coding modulation

Waveform design for pulse radar based on interrupted coding ...

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IET International Radar Conference (IRC 2023)

作者： Xiaobin Liu Qihua Wu Zhaoyu Gu Zhenyu Liu Feng Zhao Shunping Xiao The State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology National University of Defense Technology ChangSha People's Republic of China

ISBN: (数字)9781837240982

Coding modulation is utilized to design radar waveform to obtain complex properties so that the waveform is difficult to be recognized. However, traditional coding modulation brings high sidelobe in target range profile which makes the detection performance decrease. To solve this problem, the interrupted coding modulation is proposed in this paper based on the interrupted transmitting and receiving. The signal model is provided and the low sidelobe property of range profile is discussed. Constant false-alarm rate (CFAR) is utilized to evaluate the detection performance of interrupted coding modulation waveform. simulations are conducted to verify the low sidelobe property and detection performance of the proposed waveform.

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A ship detection method based on YOLOv7 in range-compressed SAR data

A ship detection method based on YOLOv7 in range-compressed ...

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IET International Radar Conference (IRC 2023)

作者： Xiangdong Tan Xiangguang Leng Jin Wang Kefeng Ji State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology National University of Defense Technology Changsha People's Republic of China

ISBN: (数字)9781837240982

Synthetic Aperture Radar (SAR) is an exceptionally effective imaging technology capable of acquiring ground information regardless of weather conditions and time of day. SAR finds extensive applications in target detection, tracking, and recognition. Despite its wide imaging coverage and high resolution, ship target detection images face several challenges. The most prominent challenge is that both traditional methods such as constant false alarm rate (CFAR) detection and deep neural network methods require complex and time-consuming imaging processing, including but not limited to range migration correction and pulse compression processes. Consequently, real-time detection becomes arduous, leading to delayed results for subsequent applications such as target monitoring and tracking. To address this issue, this study proposes a novel ship detection method that leverages deep learning techniques along with range-compressed data from SAR images to enhance immediate target perception with a convolutional neural network algorithm. The aim is to improve the accurac y and timeliness of ship detection tasks. Given the limited availability of literature on this subject matter, this paper aims to provide an analysis of the proposed method's effectiveness through experimental results while also discussing future prospects.

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Counter-reconnaissance performance analysis of amplitude coded modulation radar waveform

Counter-reconnaissance performance analysis of amplitude cod...

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IET International Radar Conference (IRC 2023)

作者： Zhenyu Liu Xiaobin Liu Qihua Wu Feng Zhao Zhiming Xu Shunping Xiao The State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology National University of Defense Technology ChangSha People's Republic of China

ISBN: (数字)9781837240982

The electronic reconnaissance systems can obtain intelligence information from technical parameters of radiation sources. Then, anti-radiation missiles can be used to destroy radiation sources, seriously threatening the survival of radar systems. To improve radar counter-reconnaissance capability, various waveforms are proposed. Among the waveforms, amplitude coded modulation (ACM) can divide the pulse into many short pulses. The signal sorting may fail so that the signal is difficult to be recognized. Therefore, the ACM signal can improve the counter-reconnaissance performance. However, the signal counter- reconnaissance performance has not been discussed. Thus, the uniform and non-periodic ACM model are proposed in this paper. Time-frequency distribution entropy and intercept probability of ACM signal are utilized to evaluate the counter-reconnaissance performance. simulations are conducted to verify the accuracy of theoretical analysis.

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Characteristics analysis of stepped frequency chirp signal using uniform interrupted modulation

Characteristics analysis of stepped frequency chirp signal u...

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IET International Radar Conference (IRC 2023)

作者： Tiehua Zhao Qihua Wu Zhiming Xu Feng Zhao Shunping Xiao The State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology National University of Defense Technology Changsha People's Republic of China

ISBN: (数字)9781837240982

The co-modulation is beneficial for increasing the anti-reconnaissance potential of radar waveform. Stepped frequency chirp (SFC) signal has the characteristics of both linear frequency modulation (LFM) signal and stepped-frequency waveform (SFW). Uniform interrupted modulation (UIM) can increase the complexity of the signal in the time domain. Therefore, the characteristics of the SFC signal with UIM are deduced in this paper. First of all, the processing method of the SFC signal is introduced. Then the characteristics of the SFC signal with UIM are analysed emphatically. The high-resolution range profile (HRRP) of the inter-pulse and intra-pulse interrupted modulation are both deduced respectively. It is concluded that the UIM between pulses brings the HRRP of the SFC signal multiple pseudo peaks extending along the range profile. However, there is no pseudo peak in the HRRP of the intra-pulse interruptedly modulated SFC signal. Signal simulation experiments are carried out with MATLAB to verify the accuracy of the theoretical analysis.

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Anechoic chamber equivalent simulation method for intermittent transceiver echo based on space target electromagnetic scattering data

Anechoic chamber equivalent simulation method for intermitte...

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IET International Radar Conference (IRC 2023)

作者： Zhenyu Qiao Xiaobin Liu Ailun Xie Qihua Wu Feng Zhao Ling Wang The State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology National University of Defense Technology Changsha People's Republic of China

ISBN: (数字)9781837240982

Electromagnetic simulations and anechoic chamber measurements are commonly used to obtain target characteristics. The use of intermittent transceiver in anechoic chamber can effectively solve the problem of the signal coupling at the receiver. However, the method of equivalent simulation between electromagnetic simulation and intermittent transceiver is rarely discussed. In this paper, an intermittent transceiver echo equivalent simulation method in anechoic chamber is proposed based on space electromagnetic scattering data. Then, the characteristics of scattering points of targets under micro-motion conditions are analyzed. Finally, the equivalent relationship and processing flow between electromagnetic scattering data and intermittent transceiver echo are discussed. simulations are conducted to verify the effectiveness of the proposed method.

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Attention Scale-Aware Deformable Network for Inshore Ship Detection in Surveillance Videos 1st

Attention Scale-Aware Deformable Network for Inshore Ship D...

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1st CAAI International Conference on Artificial Intelligence, CICAI 2021

作者： Liu, Di Zhang, Yan Zhao, Yan Zhang, Yu National Key Laboratory of Science and Technology on Automatic Target Recognition College of Electronic Science and Technology National University of Defense Technology Changsha410073 China State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Technology National University of Defense Technology Changsha410073 China

ISBN: (纸本)9783030930455

Aiming at detecting multi-scale inshore ships in surveillance videos, a one-stage detector namely Attention Scale-aware Deformable Network (ASDN) is proposed in this paper by employing two primary components including Attention Scale-aware Module (ASM) and Deformable Convolutional Network (DCN). Moreover, ASM composed of several branches of convolutions with specially designed kernels and a Convolutional Block Attention Modules (CBAM), is designed for extracting and refining non-local features of multi-scale inshore ships with large aspect ratios at the topmost feature layer. DCN is adopted to capture irregular significant features of ships by modulating input features using parameterized offsets and amplitudes at lateral connections of fine-grained feature pyramid. Experiments conducted on public Seaships7000 dataset demonstrate the contributions of ASM and DCN, and the effectiveness of our method for multi-scale inshore ship detection in surveillance videos in comparison with other Convolutional Neural Network (CNN) based methods, e.g., FPN, Libra R-CNN, SSD, YOLOv3, RefineDet. © 2021, Springer Nature Switzerland AG.

关键词： Convolution

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An Optimized Method of Low RCS Carrier Design 4

An Optimized Method of Low RCS Carrier Design

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4th International Applied Computational Electromagnetics Society Symposium in China, ACES-China 2021

作者： Zhang, Hanfei Zong, Xianzheng Nie, Zaiping Wang, Youcheng Jiang, Peng School of Electronic Science and Engineering UESTC Chengdu China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing Electro-Mechanical Engineering Institute Beijing China

ISBN: (纸本)9781733509619

Due to the strong scattering intensity of the apex of the carrier, a scheme of rounding the apex of the carrier is proposed. In this design, it is embodied in face fillet and line fillet. Based on the above designs, this paper compares the smooth transition with the sharp transition carrier, and draws a general conclusion about the low scattering carrier design method. © 2021 Applied Computational Electromagnetics Society (ACES).

关键词： Design

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Cross-Polarization suppression by Comb-Shaped slots in Microstrip Patch 13

Cross-Polarization suppression by Comb-Shaped slots in Micro...

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13th International Conference on Microwave and Millimeter Wave technology, ICMMT 2021

作者： Ma, Jing Tan, Shi-Li Ni, Si-Yuan Wang, Chen Sun, Kai Luo, Yong-Yuan Peng, Lin Beijing Simulation Center Science And Technology On Special System Simulation Laboratory Beijing100854 China 95972 Troops Of PLA Jiuquan735018 China Guilin University Of Electronic Technology Guangxi Key Laboratory Of Wireless Wideband Communication And Signal Processing Guangxi Guilin541004 China

ISBN: (纸本)9781665434379

Cross-polarization (XP) of the microstrip antenna was suppressed by etching comb-shaped slots in the patch. By cutting longitudinal comb-shaped slots on the rectangular patch, the transverse current at the patch edges that lead to cross-polarization was dammed up. Then, the co-to cross-polarization (CP-XP) ratio over entire angular range around the broadside direction was increased from 20 dB of the rectangular microstrip antenna (RMA) to 35 dB of the defected patch structure (DPS). Moreover, as the longitudinal current was little affected by the slots, the proposed structure has little effect on the other performances of the antenna (including gain, directivity, radiant principle and impedance bandwidth). As the presented structure is achieved by simple adding slots to the rectangular patch, it is very easy to be fabricated. © 2021 IEEE.

关键词： Etching

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