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An Improved Back Projection Algorithm for Terahertz Imaging

IEEE Sensors Journal 2025年第10期25卷 17761-17768页

作者： Wang, Guanwen Qi, Feng Shenyang University of Technology School of Information Science and Engineering Shenyang110870 China Key Laboratory of Liaoning Province in Terahertz Imaging and Sensing Shenyang110169 China Shenyang Institute of Automation Key Laboratory of Opto-Electronic Information Processing Chinese Academy of Sciences Shenyang110169 China

In this article, an analytical algorithm based on inverse matrix solution is proposed to perform imaging based on near-field terahertz (THz) scan data. The computational framework of conventional back projection algorithms (BPAs) comprises four principal stages. The initial procedure discretizes the target region via structured mesh partitioning. This was followed by the subsequent computation of wave propagation time delays for each discrete pixel element. Phase correction operations were then performed to compensate for waveform distortions. Ultimately, image reconstruction was achieved through coherent integral of back propagated signals. In contrast to the conventional BPA, this proposed approach reconstructed the signal propagation model. It achieves this by transforming the back projection process into an inverse problem solution, which is then used to solve the forward propagation of the signal. It can solve the inverse problem more accurately by obtaining the actual reflectivity of each pixel of the target. The computed results are closer to the electromagnetic (EM) field distribution of the real scene, reducing the error caused by energy in the subaperture signal unrelated to the imaging region compared to BPA. The radial resolution has, moreover, been improved by over 30%. Those absorbers, which are generally invisible in radar imaging due to very weak reflections, can be visualized beyond classical BPA. In the imaging process of complex targets, enhanced precision in EM calculations facilitates more comprehensive reconstructions. The algorithm can be used for elaborate environment imaging and sensing in the future. © 2001-2012 IEEE.

关键词： Radar imaging

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WF-A2D: Enhancing Privacy with Asymmetric Adversarial Defense Against Website Fingerprinting

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IEEE Transactions on information Forensics and Security 2025年 20卷 4739-4754页

作者： Huang, Jianan Liu, Weiwei Liu, Guangjie Gao, Bo Nie, Fengyuan Nanjing University of Science and Technology School of Automation Nanjing210094 China Nanjing University of Information Science and Technology School of Electronics and Information Engineering Nanjing210044 China Key Laboratory of Intelligent Support Technology for Complex Environments Ministry of Education Nanjing210044 China

Despite the end-to-end encryption capabilities provided by network protocols such as QUIC in HTTP/3 and the additional tunneling functions offered by proxy tools like virtual private networks (VPNs) and the onion router (Tor), website fingerprinting (WF) techniques can still identify specific network services by exploiting the spatio-temporal characteristics of network traffic. Therefore, defending against WF attacks is crucial for ensuring comprehensive privacy protection for network services. Existing WF defenses typically rely on proxy-based solutions that require coordinated packet manipulations between the client and the proxy node to counteract WF attacks. These symmetric architectures cannot protect network traffic between proxy nodes and web servers from WF attacks. Furthermore, the ability to counter more powerful traffic analysis tools remains a challenging issue. In this paper, we propose WF-A2D, an asymmetric adversarial defense method against website fingerprinting for HTTP/3. WF-A2D employs a two-stage cascading adversarial learning strategy, leveraging packet direction and length patterns to enhance defense performance. Position-based perturbation vectors representing packet operations are generated for packet-by-packet manipulations to achieve real-time WF defense. Experimental results on a real-world HTTP/3-QUIC website browsing traffic dataset demonstrate that WF-A2D can achieve a defense success rate of 97.10% on average against seven state-of-the-art traffic analysis tools, while incurring less than 2% bandwidth overhead. More importantly, WF-A2D can operate independently on the client side and ensure end-to-end protection to web servers. © 2005-2012 IEEE.

关键词： HTTP

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DDCTrack： Dynamic Token Sampling for Efficient UAV Transformer Tracking 27th

DDCTrack： Dynamic Token Sampling for Efficient UAV Transfor...

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27th International Conference on Pattern Recognition, ICPR 2024

作者： Du, Guocai Zhou, Peiyong Yadikar, Nurbiya Aysa, Alimjan Ubul, Kurban College of Information Science and Engineering Xinjiang University Urumqi830046 China The Key Laboratory of Multilingual Information Technology Xinjiang University Urumqi830046 China

ISBN: (纸本)9783031783531

Although state-of-the-art transformer models have shown promising results in unmanned aerial vehicle (UAV) tracking, they come with high computational demands. Existing tracking methods aim to reduce computational complexity by controlling the number of tokens. However, this method is not effective for all tracking methods. Therefore, we propose a novel dynamic token sampling for an efficient UAV transformer tracking framework. Unlike previous transformer-based tracking methods, our method avoids the need for complex head networks like classification and regression. It solely employs our newly designed encoder, comprising three key components: Dynamic Position Embedding, Dynamic Token Sampler, and Convolutional Feed-Forward Network. This module enhances visual representation by scoring and dynamically sampling tokens, allowing for a flexible token count that adapts to target changes within each frame. We utilize a simple image-sequence contrastive loss as the loss function. Our approach not only simplifies the tracking framework, but also achieves state-of-the-art performance on multiple challenging datasets at real-time run speeds. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

关键词： Aircraft detection

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Cross-modality geometry-guided historical momentum learning for coupled noisy visible-infrared re-identification

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Multimedia systems 2025年第3期31卷 1-11页

作者： Li, Yongxi Tang, Wenzhong Xiong, Lvhong Wang, Shuai Wang, Haoming Zhu, Xi School of Computer Science and Engineering Beihang University Beijing100191 China School of Electronic Information Engineering Beihang University Beijing100191 China Information Department Army Academy of Armored Force Changchun130000 China Key Laboratory of Aerospace Mobile Communication Ministry of Industry and Information Technology Beijing100191 China State Key Laboratory of CNS/ATM Beijing100191 China

Visible-Infrared Person Re-Identification (VIReID) is an identity retrieval task between visible and infrared modalities. Existing research aims to capture shared semantic features, which can retrieve the same identity under different modalities. Although the previous methods have achieved excellent performance, they still face critical limitations: (1) Coupled Noisy Problem: Due to the complexity of cross-modality annotation and the variability in crowdsourced labeling reliability, the presence of coupled noisy labels resulting from mismatched visible-infrared pairs is unavoidable. (2) Lack of historical relevance: Current approaches to noisy label learning predominantly focus on identifying potentially noisy samples based on features from the current training step, overlooking the rich semantic information in earlier training stages. These two limitations restrict the adaptability of such methods to scenarios with coupled noisy samples. We propose a Cross-Modality Geometry-Guided Historical Momentum Learning to address these issues. Firstly, we employ a Geometry-Guided Noisy Correspondence Detector to estimate confidence weights from each sample pair. Secondly, we design a historical momentum triplet loss function, which leverages features of early training steps to capture the training trajectory, addressing the historical smoothing issue in the training process. Finally, we utilize these high-confidence samples to learn the discriminative features through an iterative framework. Extensive experiments on the SYSU-MM01 and RegDB datasets demonstrate the effectiveness of our method against the state-of-the-art VIReID methods. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.

关键词： Geometry

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Causes of Winter Persistent Extreme Cold Events in Northeastern China

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Advances in Atmospheric sciences 2025年第4期42卷 780-793页

作者： Ming YANG Qingjiu GAO Tim LI State Key Laboratory of Climate System Prediction and Risk Management/Key Laboratory of Meteorological Disaster Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and TechnologyNanjing 210044China Department of Atmospheric Sciences University of Hawaii at ManoaHonoluluHI 96822USA

Persistent(5-day or longer)extreme cold events(ECEs)over northeastern China during the boreal winter of 1979–2020 are investigated using daily minimum temperature(Tmin)from the China Meteorological Data *** extreme cooling area and intensity indices associated with the ECEs exhibit a dominant 10–40-day periodicity,indicating a close link with atmospheric intraseasonal oscillations(ISOs).The ECEs are categorized into W-and *** the former,the low-frequency cooling associated with the ISO first penetrates into the western boundary of the northeastern China domain and later occupies the entire domain at its peak *** upper-tropospheric circulation associated with this type is characterized by a northwest–southeast-oriented Rossby wave train,expanding from the Ural Mountains to the western Pacific *** the latter,the cooling invades the northern boundary first and then penetrates into the entire *** upper tropospheric precursory signal associated with this type is a zonally oriented negative geopotential height anomaly,which slowly moves southward.A downward-propagating signal is observed in the stratospheric potential vorticity field prior to the peak cooling,implying a possible stratospheric *** addition to the W-and N-types,ECEs can also occur in a localized region near either at the northern or southern boundary of the domain.

关键词： extreme cold events low-frequency ISO mode Rossby wave train composite analysis downward propagation potential vorticity

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Chain-of-Specificity: Enhancing Task-Specific Constraint Adherence in Large Language Models 31

Chain-of-Specificity: Enhancing Task-Specific Constraint Adh...

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31st International Conference on Computational Linguistics, COLING 2025

作者： Wei, Kaiwen Zhong, Jiang Zhang, Hongzhi Zhang, Di Jin, Li Yu, Yue Zhang, Jingyuan College of Computer Science Chongqing University China Kuaishou Inc. China Key Laboratory of Network Information System Technology Aerospace Information Research Institute Chinese Academy of Sciences China

ISBN: (纸本)9798891761964

Large Language Models (LLMs) exhibit remarkable generative capabilities, enabling the generation of valuable information. Despite these advancements, previous research found that LLMs sometimes struggle with adhering to specific constraints (e.g., in specific place or at specific time), at times even overlooking them, which leads to responses that are either too generic or not fully satisfactory. Existing approaches attempted to address this issue by decomposing, rewriting input instructions, or reflecting on prior failings, yet they fall short in adequately emphasizing specific constraints and in unlocking the underlying knowledge (e.g., programming within the context of software development). In response, this paper proposes a simple yet effective method Chain-of-Specificity (CoS). Specifically, CoS iteratively emphasizes the specific constraints in the input instructions, unlocks knowledge within LLMs, and refines responses. Experiments conducted on publicly available and self-build complex datasets demonstrate that CoS outperforms existing methods in enhancing generated content especially for the specificity. Besides, as the number of specific constraints increase, other baselines falter, while CoS still performs well. Moreover, we show that distilling responses generated by CoS effectively enhances the ability of smaller models to follow the constrained instructions. © 2025 Association for Computational Linguistics.

关键词： Computational linguistics

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Glass catfish inspired subaquatic abrasion-resistant anti-fouling window fabricated by femtosecond laser electrodeposition

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International Journal of Extreme Manufacturing 2025年第1期7卷 383-393页

作者： Jialiang Zhang Fangzheng Ren Qing Yang Qingyun Ma Jie Liang Yizhao Meng Xiaodan Gou Chongxiao Xia Feng Chen State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information School of Electronic Science and EngineeringXi’an Jiao Tong UniversityXi’an 710049People’s Republic of China School of Instrument Science and Technology Xi’an Jiaotong UniversityXi’an 710049People’s Republic of China

Transparent materials utilized as underwater optical windows are highly vulnerable to various forms of pollution or abrasion due to their intrinsic hydrophilic *** susceptibility is particularly pronounced in underwater environments where pollutants can impede the operation of these optical devices,significantly degrading or even compromising their optical *** glass catfish,known for its remarkable transparency in water,maintains surface cleanliness and clarity despite exposure to contaminants,impurities abrasion,and hydraulic *** by the glass catfish’s natural attributes,this study introduces a new solution named subaquatic abrasion-resistant and anti-fouling window(SAAW).Utilizing femtosecond laser ablation and electrodeposition,the SAAW is engineered by embedding fine metal bone structures into a transparent substrate and anti-fouling sliding layer,akin to the sturdy bones among catfish’s *** approach significantly bolsters the window’s abrasion resistance and anti-fouling performance while maintaining high light *** sliding layer on the SAAW’s surface remarkably reduces the friction of various liquids,which is the reason that SAAW owns the great anti-fouling *** SAAW demonstrates outstanding optical clarity even after enduring hundreds of sandpaper abrasions,attributing to the fine metal bone structures bearing all external forces and protecting the sliding layer of ***,it exhibits exceptional resistance to biological adhesion and underwater *** a green algae environment,the window remains clean with minimal change in transmittance over one ***,it retains its wettability and anti-fouling properties when subjected to a depth of 30 m of underwater pressure for 30 ***,the SAAW prepared by femtosecond laser ablation and electrodeposition presents a promising strategy for developing stable optical windows in liquid environments.

关键词： anti-fouling femtosecond laser subaquatic window slippery surface abrasion resistance

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High-resolution multilevel reversible color printing based on Sb2S3 phase change materials

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Photonics Research 2025年第3期13卷 661-670页

作者： ZHIWEI LI TAO WEI LIHAO SUN JING HU MIAO CHENG QIANQIAN LIU RUIRUI WANG YUN LING WANFEI LI BO LIU Suzhou Key Laboratory for Nanophotonic and Nanoelectronic Materials and Its Devices School of Materials Science and EngineeringSuzhou University of Science and Technology School of Electronic&Information Engineering Suzhou University of Science and Technology

Phase change material is promising for a color-changing device owing to its substantial optical contrast between amorphous and crystalline states. However, current phase change material, such as Ge2Sb2Te5thin film, has restrained the color-changing performance owing to its high optical absorption. Sb2S3thin film, exhibiting large refractive index difference and low absorption between crystalline and amorphous states, is a promising alternative. Here, a color device with Al∕Sb2S3∕SiO2-stacking layer is prepared, and high-resolution, multilevel,reversible color printing is realized. Wide color gamut is successfully obtained by controlling either the Sb2S3thickness or its crystallization degree. Furthermore, the proposed color device can be patterned by direct laser writing and erased by a picosecond laser system, possessing good reversible cycling stability. High-resolution pixel higher than 42,000 DPI is further implemented. Moreover, a flexible color device is also fabricated, which possesses superior angular insensitivity from 10° to 60°and is hardly faded after bending and folding 10 *** work may have wide applications in the fields of color printing, flexible displays, wearable optoelectronic devices, and so forth.

关键词： Electron beam lithography Optical absorption Refractive index Surface plasmon resonance Thin films Waveguide modes

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Eddy Detection of Lakes in the Qinghai–Tibet Plateau Based on Optical Remote Sensing and Deep Learning

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IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 2025年 18卷 11996-12007页

作者： Bai, Bingxin Mu, Lixia Yang, Jie Huang, Baoxiang Ma, Chunyong Chen, Ge Ocean University of China Faculty of Information Science and Engineering Qingdao266100 China Laoshan Laboratory Qingdao266237 China Ocean University of China College of Marine Technology Qingdao266100 China Qingdao University College of Computer Science and Technology Qingdao266071 China

Lake eddies are dynamic phenomena prevalent in large lake systems, playing a critical role in affecting lake physics, nutrient transport, and ecological balance. Efficient and precise detection of these features is essential for advancing scientific understanding of lake dynamics and for improving environment management strategies. Despite their importance, the study of lake eddies remains under-explored, and current detection methods are insufficient. This study addresses this gap by proposing a lake eddy identification framework based on the YOLOv7 deep learning model, utilizing Landsat 8/9 satellite imagery acquired from April 2013 to December 2023. Qinghai Lake, Selin Co, and Nam Co on the Qinghai–Tibet Plateau were selected as the study areas. The method involves the development of an image enhancement process to optimize the visibility of lake eddies in remote sensing imagery, followed by the implementation of the YOLOv7 model for detection. The framework identified 912 cyclonic eddies and 102 anticyclonic eddies on the three aforementioned lakes, providing detailed information on their spatial distribution and morphology. This approach demonstrates significant potential for advancing the study of lake hydrodynamics and energy transport substances in aquatic ecosystems. © 2008-2012 IEEE.

关键词： Aquatic ecosystems

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Classification of Neuropsychiatric Disorders via Brain-Region-Selected Graph Convolutional Network

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IEEE Transactions on Neural systems and Rehabilitation engineering 2025年 33卷 1664-1672页

作者： Qin, Zhenzhe Li, Yongbo Song, Xiaoying Chai, Li Wuhan University of Science and Technology School of Electronic Information Wuhan430081 China Zhejiang University State Key Laboratory of Industrial Control Technology College of Control Science and Engineering Hangzhou310027 China

For the classification of patients with neuropsychiatric disorders based on rs-fMRI data, this paper proposed a Brain-Region-Selected graph convolutional network (BRS-GCN). In order to effectively identify the most significant biomarkers associated with disease, we designed a novel ROI pooling score function. Additionally, we also designed a comprehensive loss function, including a group-level consistency loss function for preserving the same brain regions in subjects of the same category, and an anti-consistency function for maximizing brain region preservation differences between subjects of different categories. On the basis of the ROI graph, we directly incorporate the non-imaging information of the subjects in the network training. Experimental results on two public datasets, ABIDE and ADNI, validate the superiority of the model proposed in this paper, and the qualitative results of the biomarkers demonstrate the potential application of the model in medical diagnosis and treatment of neuropsychiatric disorders. © 2001-2011 IEEE.

关键词： Neurons

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