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UAV image target localization method based on outlier filter and frame buffer

Chinese Journal of Aeronautics 2024年第7期37卷 375-390页

作者： Yang WANG Hongguang LI Xinjun LI Zhipeng WANG Baochang ZHANG Institute of Unmanned System Beihang UniversityBeijing 100191China School of Electronics and Information Engineering Beihang UniversityBeijing 100191China Institute of Artificial Intelligence Beihang UniversityBeijing 100191China

With rapid development of UAV technology,research on UAV image analysis has gained *** the existing techniques of UAV target localization often rely on additional equipment,a method of UAV target localization based on depth estimation has been ***,the unique perspective of UAVs poses challenges such as the significant field of view variations and the presence of dynamic objects in the *** a result,the existing methods of depth estimation and scale recovery cannot be directly applied to UAV ***,there is a scarcity of depth estimation datasets tailored for UAV perspectives,which makes supervised algorithms *** address these issues,an outlier filter is introduced to enhance the applicability of depth estimation networks to target localization.A frame buffer method is proposed to achieve more accurate scale recovery,so as to handle complex scene textures in UAV *** proposed method demonstrates a 14.29%improvement over the *** with the average recovery results from UAV perspectives,the difference is only 0.88%,approaching the performance of scale recovery using ground truth ***,to overcome the limited availability of traditional UAV depth datasets,a method for generating depth labels from video sequences is *** to state-of-the-art methods,the proposed approach achieves higher accuracy in depth estimation and stands for the first attempt at target localization using image *** algorithm and dataset are available at https://***/uav-tan/uav-object-localization.

关键词： Object localization Deep learning Depth estimate Scale recovery Unmanned Aerial Vehicle(UAV)

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A Case Study on the Rapid Rain-to-Snow Transition in Late Spring 2018 over Northern china:Effects of Return Flows and Topography

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Journal of Meteorological Research 2022年第1期36卷 107-127页

作者： Wenlong ZHANG Xiaopeng CUI Bolong DUAN Bo YU Runxia GUO Haiwen LIU Institute of Urban Meteorology China Meteorological AdministrationBeijing 100089 Key Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 Lanzhou Central Meteorological Observatory Lanzhou 730020 Beijing Weather Forecast Center Beijing 100089 Department of aviation Meteorology Civil Aviation University of ChinaTianjin 300300 University of Chinese Academy of Sciences Beijing 100049

Phase changes in the precipitation processes of early winter and late spring in midlatitude regions represent challenges when forecasting the timing and magnitude of *** 4 April 2018,a heavy snow process occurred in Beijing and northwestern Hebei Province,becoming the most delayed occurrence of heavy spring snow ever recorded over Beijing in the last 30 *** paper uses observational and numerical simulation data to investigate the causes for the rapid rain-to-snow(RRTS)phase transition during this *** following results are obtained.(1)Return flows(RFs),an interesting type of easterly wind,including those at 1000,925,and 800 hPa,played an important role in this heavy snow process and presented a characteristic"sandwich"*** RFs,complex topography,and snow particles that dominated the clouds,were the three key factors for the RRTS transition.(2)The RRTS transition in the plains was directly related to the RF at 925 hPa,which brought about advective cooling initiated approximately 4-6 h before the onset of ***,the RF played a role of diabatic cooling when snow particles began to fall at the onset of precipitation.(3)The RRTS transition in the northern part of the Taihang Mountains was closely related to the relatively high altitude that led to a lower surface temperature owing to the vertical temperature lapse *** immediately before and after the onset of precipitation,the snow particles in clouds entrained the middle-level cold air downward,causing the melting layer(from surface to the 0℃-isotherm level)to become very thin;and thus the snow particles did not have adequate time to melt before falling to the ground.(4)The rapid RRTS over the Yanqing mountainous area in the northwest of Beijing could have involved all the three concurrent mechanisms:the advective cooling of RF,the melting cooling of cloud snow particles,and the high-altitude *** with that in the plain area with less urbanization the duration

关键词： midlatitude heavy snow return flow phase transition Bohai Sea cold pool complex terrain numerical simulation

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Damage sensitivity of a wing-type leading edge structure impacted by a bird

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Chinese Journal of Aeronautics 2023年第5期36卷 328-343页

作者： Jun LIU Chunyang ZHANG Bopeng JUAN Zhenhua LI Chao ZHANG Yulong LI School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China

On the windward side of an aircraft,the components with higher probability of impact with birds are the wing-type leading edge structures,such as the wing and tail.A study on the damage sensitivity of a wing-type leading edge structure under bird strikes was presented in this ***,a bird strike test was carried out on a *** principles of the bird strike test equipment and method were introduced in detail,including the bird strike test system,bird projectile production process and data acquisition *** dynamic strain measurement results,the high-speed camera videos,and the final deformation and damage morphology observations of the structure were *** on the coupled Smooth Particle Hydrodynamics(SPH)-Finite Element Method(FEM),the commercial software PAM-CRASH was used to simulate the process of a bird strike with the *** good agreement between the finite element simulation results and the experimental results shows that the calculation method and the numerical model presented in this paper were *** this basis,wing-type leading edge structures can be designed by adding triangular *** bird strike resistances of an original structure and improved structure were studied by numerical *** calculated results show that the improved wing-type leading edge structure is less damaged than the original structure under bird *** improved leading edge structure satisfied the anti-bird strike airworthiness requirements,as the thickness of the triangular support was 1.2 mm,and the weight of the structure was reduced by 0.87 kg compared with the original *** indicated that the bird strike resistance of the improved structure is better than that of the original structure,and the improved design of the wing-type leading edge structure presented in this paper is reasonable.

关键词： Bird impact Damage sensitivity FEM SPH Wing-type leading edge

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A Robust Conformer-Based Speech Recognition Model for Mandarin Air Traffic Control

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Computers, Materials & Continua 2023年第10期77卷 911-940页

作者： Peiyuan Jiang Weijun Pan Jian Zhang Teng Wang Junxiang Huang College of Air Traffic Management Civil Aviation Flight University of ChinaDeyang618307China East china Air Traffic Management Bureau Xiamen Air Traffic Management StationXiamen361015China

This study aims to address the deviation in downstream tasks caused by inaccurate recognition results when applying Automatic Speech Recognition(ASR)technology in the Air Traffic Control(ATC)*** paper presents a novel cascaded model architecture,namely Conformer-CTC/Attention-T5(CCAT),to build a highly accurate and robust ATC speech recognition *** tackle the challenges posed by noise and fast speech rate in ATC,the Conformer model is employed to extract robust and discriminative speech representations from raw *** the decoding side,the Attention mechanism is integrated to facilitate precise alignment between input features and output *** Text-To-Text Transfer Transformer(T5)language model is also introduced to handle particular pronunciations and code-mixing issues,providing more accurate and concise textual output for downstream *** enhance the model’s robustness,transfer learning and data augmentation techniques are utilized in the training *** model’s performance is optimized by performing hyperparameter tunings,such as adjusting the number of attention heads,encoder layers,and the weights of the loss *** experimental results demonstrate the significant contributions of data augmentation,hyperparameter tuning,and error correction models to the overall model *** the Our ATC Corpus dataset,the proposed model achieves a Character Error Rate(CER)of 3.44%,representing a 3.64%improvement compared to the baseline ***,the effectiveness of the proposed model is validated on two publicly available *** the AISHELL-1 dataset,the CCAT model achieves a CER of 3.42%,showcasing a 1.23%improvement over the baseline ***,on the LibriSpeech dataset,the CCAT model achieves a Word Error Rate(WER)of 5.27%,demonstrating a performance improvement of 7.67%compared to the baseline ***,this paper proposes an evaluation criterion for assessing the robustness of ATC speech recognit

关键词： Air traffic control automatic speech recognition conformer robustness evaluation T5 error correction model

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Impact of receiver inter-frequency bias residual uncertainty on dual-frequency GBAS integrity

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Chinese Journal of Aeronautics 2022年第11期35卷 349-362页

作者： Kai KANG Kun FANG Yanbo ZHU Yuan LIU Zhipeng WANG Qiang LI National Key Laboratory of CNS/ATM School of Electronic and Information EngineeringBeihang UniversityBeijing 100083China Research Institute for Frontier Science Beihang UniversityBeijing 100083China

Dual-Frequency Ground-Based Augmentation Systems(GBAS)can be affected by receiver Inter-Frequency Bias(IFB)when Ionosphere-Free(Ifree)smoothing is *** the framework of the proposed GBAS Approach Service Type F(GAST-F),the IFB in the Ifree smoothed pseudorange can be ***,IFB residual uncertainty still exists,which may threaten the integrity of the *** paper presents an improved algorithm for the airborne protection level considering the residual uncertainty of IFBs to protect the integrity of dual-frequency *** IFB residual uncertainty multiplied by a frequency factor is included in the Ifree protection level together with the uncertainty of other error *** verify the proposed protection level algorithm,we calculate the IFB residual uncertainties of ground reference receivers and user receiver based on BDS B1I and B3I dual-frequency observation data and carry out a test at the Dongying Airport GBAS *** results show that the proposed Ifree protection level with IFB residual uncertainty is 1.48 times the current protection level on *** probability of Misleading Information(MI)during the test is reduced from 3.2×10^(-4)to the required *** is proven that the proposed protection level can significantly reduce the integrity risk brought by IFB residual uncertainty and protect the integrity of dual-frequency GBAS.

关键词： GBAS Integrity Inter-frequency bias Ionosphere-free smoothing Vertical protection level

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