{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T02:05:05Z","timestamp":1788833105333,"version":"build-2803163510"},"reference-count":40,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,3,19]],"date-time":"2026-03-19T00:00:00Z","timestamp":1773878400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Zhejiang Provincial Universities and Research Institutes","award":["JX6311070723"],"award-info":[{"award-number":["JX6311070723"]}]},{"name":"Zhejiang Ocean University - Jurong Petroleum and Natural Gas University - Enterprise Joint Laboratory Development Project","award":["12014260525007"],"award-info":[{"award-number":["12014260525007"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Side-scan sonar (SSS) serves as the primary perceptual instrument for Autonomous Underwater Vehicles (AUVs) in large-scale marine search and rescue (SAR) operations. However, the detection of critical targets is frequently hindered by severe hydro-acoustic noise, the spatial discontinuity of wreckage, and the weak visual signatures of small targets. To surmount these challenges, this paper presents WPG-DetNet. First, we introduce a Wavelet-Embedded Residual Backbone (WERB) to reconstruct the conventional downsampling paradigm. By substituting standard pooling with the Discrete Wavelet Transform (DWT), this architecture explicitly disentangles high-frequency noise from structural information in the frequency domain, thereby achieving the adaptive preservation of edge fidelity for large human-made targets while filtering out speckle interference. Then, addressing the distinct challenge of discontinuous aircraft wreckage, the framework further incorporates a Debris Graph Reasoning Module (D-GRM). This module models scattered fragments as nodes in a topological graph to capture long-range semantic dependencies, transforming isolated instance recognition into context-aware scene understanding. Finally, to bridge the gap between AI and underwater physics, we design a Shadow-Aided Decoupling Head (SADH) equipped with a physics-informed geometric loss. By enforcing mathematical consistency between target height and acoustic shadow length, this mechanism establishes a rigorous discriminative criterion capable of distinguishing weak-echo human bodies from seabed rocks based on shadow geometry. Experiments on the SCTD dataset demonstrate that WPG-DetNet achieves a mean Average Precision (mAP50) of 97.5% and a Recall of 96.9%. Quantitative analysis reveals that our framework outperforms the classic Faster R-CNN by a margin of 12.8% in mAP50 and surpasses the Transformer-based RT-DETR-R18 by 5.6% in high-precision localization metrics (mAP50:95). Simultaneously, WPG-DetNet maintains superior efficiency with an inference speed of 62.5 FPS and a lightweight parameter count of 16.8 M, striking an optimal balance between robust perception and the real-time constraints of AUV operations.<\/jats:p>","DOI":"10.3390\/s26061938","type":"journal-article","created":{"date-parts":[[2026,3,19]],"date-time":"2026-03-19T15:38:01Z","timestamp":1773934681000},"page":"1938","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Physics-Informed Side-Scan Sonar Perception: Tackling Weak Targets and Sparse Debris via Geometric and Frequency Decoupling"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-4812-1377","authenticated-orcid":false,"given":"Bojian","family":"Yu","sequence":"first","affiliation":[{"name":"Jurong Petroleum and Natural Gas University Enterprise Joint Laboratory, Zhejiang Ocean University, Zhoushan 316022, China"},{"name":"School of Marine Engineering Equipment, Zhejiang Ocean University, Zhoushan 316022, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rongsheng","family":"Lin","sequence":"additional","affiliation":[{"name":"Jurong Energy (Xinjiang) Co., Ltd., Bayingolin Mongol Autonomous Prefecture 841600, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8964-9794","authenticated-orcid":false,"given":"Hanxiang","family":"Zhou","sequence":"additional","affiliation":[{"name":"Jurong Petroleum and Natural Gas University Enterprise Joint Laboratory, Zhejiang Ocean University, Zhoushan 316022, China"},{"name":"School of Marine Engineering Equipment, Zhejiang Ocean University, Zhoushan 316022, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jianxiong","family":"Zhang","sequence":"additional","affiliation":[{"name":"Jurong Petroleum and Natural Gas University Enterprise Joint Laboratory, Zhejiang Ocean University, Zhoushan 316022, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xinwei","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Foreign Languages, Zhejiang Ocean University, Zhoushan 316022, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"899","DOI":"10.1002\/rob.70077","article-title":"Challenges and Advances in Underwater Sonar Systems and AI-Driven Signal Processing for Modern Naval Operations: A Systematic Review","volume":"43","author":"Das","year":"2025","journal-title":"J. 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