水下无人系统学报

Design and Performance Analysis of a Pressure-Resistant and Sound-Absorbing Integrated Coating with High-Transmittance Composite

Tang Jian, Jin Zhuohao, Lu Chen, Chen Wenjiong

, Available online , doi: 10.11993/j.issn.2096-3920.2026-0001

[Abstract](25) [FullText HTML] (8) [PDF 1345KB](7)

Abstract:
To address the significant degradation in sound absorption performance of conventional cavity-type rubber coatings under high hydrostatic pressure, a pressure-resistant and sound-absorbing integrated coating with a high-transmission composite layer is proposed. Based on the finite element method, a numerical model considering hydrostatic pre-stress, moving mesh, and acoustic-structure coupled frequency-domain perturbation is established to investigate the sound transmission performance of the composite layer and the sound absorption characteristics of three cavity configurations under different static pressures. The results show that, under hydrostatic pressures of 0-9 MPa, both glass fiber reinforced plastic(GFRP) and carbon fiber reinforced plastic(CFRP) layers maintain high sound transmission coefficients with limited pressure sensitivity. The rectangular, petal-shaped, and conical cavity coatings with the high-transmission composite layer all achieve sound absorption coefficients generally above 0.7 in the 4-10 kHz range, with only slight variation under different pressures. The high-transmission composite layer effectively suppresses pressure-induced deformation of the cavity structure, thereby improving the stability of sound absorption performance under high-pressure conditions. This study provides a reference for the design of underwater sound-absorbing coatings in high-pressure environments.

Research on Active Control of Raft–Cylindrical Shell Systems Based on Fractional-Order FxLMS

CHENG Weipeng, WU Wenwei, WU Demu, YIN Zhiyong

, Available online , doi: 10.11993/j.issn.2096-3920.2026-0020

[Abstract](8) [FullText HTML] (5) [PDF 2411KB](6)

Abstract:
To address the challenge of suppressing low-frequency line-spectrum vibrations in mechanical equipment such as the main and auxiliary machinery of underwater vehicles, this paper proposes a DFOFxLMS(dual-channel fractional-order filtered-x least mean square) algorithm based on the fractional-order gradient descent method. The control performance of algorithms with different fractional orders is analyzed and compared through simulations. An experimental platform for active vibration control based on a floating raft–cylindrical shell structure is established. Comparative experiments under various operating conditions demonstrate that, compared with single-channel control strategies, the proposed dual-channel collaborative control scheme exhibits significant advantages in suppressing the overall vibration of the floating raft–cylindrical shell system. Furthermore, it demonstrates excellent engineering practicality and control effectiveness under dual-frequency line-spectrum disturbance scenarios.

Method of Vision-Task-Friendly Underwater Image Enhancement

CHENG Miao, WEI Yanhui, SUN Wenbin, HOU Tongtong

, Available online , doi: 10.11993/j.issn.2096-3920.2026-0023

[Abstract](8) [FullText HTML] (5)

Abstract:
Underwater images suffer from severe color and structural distortions, which degrade the performance of various underwater vision tasks. Existing underwater image enhancement methods focus on improving visual appearance while ignoring the necessity of optimizing the downstream vision tasks. To address this issue, this paper proposes a Visual Task-Friendly underwater image enhancement Network(VTF-Net). Specifically, we first design a novel Spatial-Frequency Fusion enhancement module(SFF), which can significantly improve the model’s perception of texture details and image fidelity. Second, to achieve efficient information transmission between the encoder and decoder, we introduce a Multi-Scale Cross-Attention module(MSCA) and a Bottleneck Attention module(BNA), which enhance the perception of global gradients while ensuring efficient feature extraction, thereby effectively alleviating color cast and blurring. Finally, in line with the concept of visual task-friendliness, we propose a detection loss function that guides the optimization direction of the model by incorporating underwater object detection results. Experimental results demonstrate that the proposed method achieves superior performance in both qualitative and quantitative evaluations, and obtains the best result in the application experiment of underwater object detection.

Tunable Underwater Acoustic Stealth Capability of Mechanically Reconfigurable Negative Stiffness Meta-structures

GONG Xiaokun, LI Qing, YANG Deqing, WANG Yingguang

, Available online , doi: 10.11993/j.issn.2096-3920.2026-0024

[Abstract](15) [FullText HTML] (10)

Abstract:
This study addresses the urgent need for vibration control and acoustic stealth in underwater equipment by exploring mechanically reconfigurable negative stiffness metamaterials (NSM) for tunable acoustic performance. In this paper, we optimally designed two NSM unit cells exhibiting distinct bandgaps upon mechanical deformation, systematically analyzed their bandgap characteristics during deformation, and constructed homogeneous/gradient sandwich panel negative stiffness meta-structure. Using vibro-acoustic coupling finite element method, their underwater sound radiation characteristics under different assembly sequences and loading conditions were analyzed. Results demonstrate that the mechanical reconfigurability of NSMs enables flexible tuning of wave propagation performance in meta-structures, while gradient sequences can broaden frequency ranges of high sound insulation. This study provides theoretical and design references for developing lightweight functional structures for underwater acoustic stealth and camouflage.

Experimental Study on Active Control for Propeller Radiated Sound Fields

LIU Kuokuo, SUN Hongling, SUN Luyang, LI Shixun, CHENG Xiaobin, LI Yuhui, CAO Rongning, WANG Han

, Available online , doi: 10.11993/j.issn.2096-3920.2026-0034

[Abstract](13) [FullText HTML] (4)

Abstract:
When an underwater vehicle is in motion, the propeller will generate significant low-frequency line spectrum radiation noise. To verify the control effectiveness of different active control strategies on the line spectrum radiation noise, an active control experiment on the radiation acoustic field was conducted for the first time on a real small-scale propeller. An underwater test platform, which includes a propeller, sensors, secondary force actuators, secondary sound sources, and a control system, was constructed for active noise control(ANC), active vibration control(AVC), and active noise and vibration control(ANVC) tests. By altering the working conditions of the propeller, the suppression effects of different control strategies on the underwater radiated sound pressure of the propeller were tested. The results show that active noise control has a significant and stable effect on suppressing the low-frequency line spectrum noise of the propeller, and performs best under high rotational speed conditions; active vibration control has limitations and local control may lead to sound field reconstruction; active acoustic-vibration combined control shows potential for collaborative control in some operating conditions, but the control strategy and collaborative mechanism need to be further optimized. The research results provide an experimental basis and technical support for the engineering control of underwater propeller radiated noise.

Design and simulation of mechanical biomimetic fish tail driven by EAP material

WANG Sijiao, ZHANG Haoyi, CHENG Yanlin, CAO Kaiming

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0164

[Abstract](10) [FullText HTML] (4) [PDF 1812KB](7)

Abstract:
Against the backdrop of advancing marine conservation and exploration, traditional underwater propulsion systems are often hampered by inherent drawbacks such as structural complexity and low motion efficiency. In contrast, flexible materials have emerged as a research focus in underwater actuation due to their superior adaptability, high safety, and remarkable flexibility. Leveraging the favorable core properties of Electroactive Polymer (EAP), namely its high energy density and efficient electromechanical coupling, this study introduces a novel biomimetic caudal fin actuator. This design incorporates a spring element to harness flexural deformation and elastic recovery, effectively simulating the cyclic contraction and relaxation dynamics characteristic of the Body and/or Caudal Fin (BCF) propulsion mode in fish, thereby achieving continuous, compliant changes akin to tail musculature. Based on hydrodynamic theory, the coupled interaction mechanism between fin kinematics and thrust generation is systematically analyzed. An instantaneous mechanical model for fin-ray oscillation is developed and solved by incorporating experimental data. A three-dimensional numerical simulation model is established using Fluent software. The validity of the proposed mechanical model is confirmed through comparative analysis between the computational results from dynamic meshing and the model's predictions. This work provides reliable theoretical support and experimental evidence for the design and development of new biomimetic robotic fish driven by this innovative actuator.

A Study on Flow Noise Simulation Using the SUBOFF Model Based on Bayesian Sparse Grids

LIU Jiayu, LIU Peng, JIN Hui, YIN Yibing, LIU Jiang, LIU Guijie, WEN Zhenhua

, Available online , doi: 10.11993/j.issn.2096-3920.2026-0033

[Abstract](15) [FullText HTML] (5) [PDF 2322KB](10)

Abstract:
This paper proposes a Bayesian-based sparse grid correction method to address the degradation in flow-induced noise prediction accuracy arising from mismatched spatial scales between finite element model grid dimensions and turbulent boundary layer pressure in large-scale sparse grids. Using the DARPA SUBOFF 5470 submarine model as a case study, numerical simulations were conducted to investigate its applicability in predicting far-field acoustic radiation from submarine appendages. The study employs Corcos's self-spectrum and normalised cross-power spectral density function computational model, utilising virtual mesh refinement to compensate for the spatial correlation characteristics of low-frequency turbulent pulsation pressures. By integrating engineering characteristics and operational environments, the correlation between pulsation pressure influencing factors is extracted, ultimately constructing a Bayesian network model for flow-induced noise excitation forces. Employing wall-resolved LES (WRLES) coupled with the Ffowcs Williams-Hawkings (FW-H) acoustic analogy method, the flow-induced noise obtained from the modified simulation calculations and the results of the refined mesh fluid-structure interaction simulation. Acoustic characteristics are contrasted between the SUBOFF 5470 configuration with appendages and the bare hull. Simulation experiments demonstrate that the Bayesian sparse grid correction method effectively compensates for prediction errors arising from mismatches between grid scales and turbulence-relevant scales, validating the method's validity and applicability.

Research on Ejection Technology of Underwater Piston-type Pyrotechnic Nozzle Device

ZHANG Jinhui, SUN guorui

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0108

[Abstract](10) [FullText HTML] (7)

Abstract:
With the development of undersea vehicle technology, higher design requirements of small volume, light weight, low disturbance and low noise have been put forward for its ejection and separation device. In this paper, a systematic study is carried out on the key technologies of the piston-type ejection pyrotechnic nozzle device. The working principle of the device and the operational process of projectile ejection are clarified through principle analysis. Based on the zero-dimensional internal ballistic model, the pressure-time characteristics of the combustion chamber are numerically simulated and calculated. The two-dimensional steady-state numerical simulation of the Laval nozzle flow field is conducted by using FLUENT software, and the design scheme is verified through land-based and underwater ejection tests. The research results show that the design scheme adopting the convergent-divergent Laval nozzle can significantly improve the energy conversion efficiency, effectively reduce the device volume and the propellant charge amount, thus enhancing the system safety. By innovatively applying the Laval nozzle to the piston-type ejection pyrotechnic device, the key problems of large energy loss, large system volume and insufficient safety in the traditional underwater ejection technology are successfully solved, which provides theoretical basis and technical reference for the optimal design and multi-platform application of underwater ejection devices.

A high-precision motion control strategy for valve-controlled cylinders

LIU Guoqing, WANG Jianxin, Ping Zilong, Zhang Xiaoming

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0110

[Abstract](10) [FullText HTML] (9) [PDF 989KB](10)

Abstract:
As a key actuator in electro-hydraulic servo systems, the motion precision of the valve-controlled cylinder is pivotal to the system's stability, responsiveness, and final positioning accuracy. Practical applications, however, are plagued by issues like nonlinear friction, parametric uncertainty, and external disturbances, which challenge conventional control methods. proportional-integral-derivative(PID) control exhibits poor robustness, while sliding mode control induces detrimental chattering. To overcome these drawbacks, an advanced adaptive robust control strategy featuring fast dynamic compensation and nonlinear robust feedback is proposed in this work. Comparative simulation results confirm the superior performance of the proposed controller over PID and sliding mode control(SMC) in tracking precision and robustness.

Operational transfer path analysis with total least-squares method

GUI Juntao, FAN Xiaobo, MAN Shilin, WU Song

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0024

[Abstract](16) [FullText HTML] (10) [PDF 2159KB](10)

Abstract:
The operational transfer path analysis(OTPA) utilizes response data under different working conditions to decompose and predict vibration and noise, and is therefore widely used in various engineering fields. However, the response data of vibration noise inevitably contains errors, which seriously affect the accuracy of the transfer path analysis. To reduce the impact of errors and improve the accuracy of the transfer rate function matrix, the total least squares method is used to estimate the transfer rate function matrix, and then the analysis of the working condition transfer path is carried out. Compared to traditional methods, the overall least squares method takes into account the errors in both the target point and indicator point data. In numerical model simulations and experimental model of open condition transmission path analysis, least squares method and overall least squares method were applied to obtain the contribution of each path. The simulation results show that the contribution identified by the overall least squares method is more consistent with the contribution of classical transmission path analysis, indicating that compared with the regularized least squares method, the total least-squares method has better applicability in the analysis of transmission paths under working conditions, effectively improving the accuracy of transmission path analysis under working conditions.

Research on the influence of biomimetic serrated structure on the hydrodynamic noise characteristics of toroidal propeller

MAO Xinpei, LIU Peng, LIU Jiang, KANG Ludi, JIN Hui, YIN Yibing

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0141

[Abstract](20) [FullText HTML] (10) [PDF 7190KB](15)

Abstract:
The toroidal propeller has emerged as a research hotspot owing to its potential for enhancing propulsion efficiency and achieving effective noise control. Biomimetic principles offer a novel technical approach to noise reduction. However, the application research of biomimetic modification in the field of underwater propellers is still relatively scarce. Therefore, this study aims to explore the mechanism of the influence of biomimetic serrated structures on the hydrodynamic noise of toroidal propellers. Inspired by the acoustic characteristics of owl wing-edge serrations and based on the parametric modeling method of toroidal propeller, a biomimetic variant with trailing-edge serration features was designed. Based on computational fluid dynamics(CFD) and the FW-H acoustic analogy theory, the characteristics of the propeller flow field and the variation patterns of non-cavitation noise under different serration sizes were systematically analyzed. The research results show that the biomimetic structure has a modulation effect on the broadband noise components of the propeller, achieving a noise reduction of 0.3 to 1.5 dB within the radial observation plane; in the area of the blade tip and the rear part of the middle section, the noise reduction effect is significantly dependent on the serration size and the operating speed. That is, at high rotational speeds, the noise amplitude is effectively reduced, while at low rotational speeds, the noise in specific areas slightly increases. This study elucidated the influence of bionic serrated parameters on noise, providing a theoretical foundation and optimization direction for the bionic design of low-noise underwater propellers.

Underwater Vibro-acoustic Coupling Characteristics of a Simply Supported Plate Coupled with a Quasi-Zero Stiffness Vibration Isolation

TANG Jiajing, ZOU Shaohua, WANG Qiang, ZHOU Jiaxi

, Available online , doi: 10.11993/j.issn.2096-3920.2026-0018

[Abstract](29) [FullText HTML] (19) [PDF 1805KB](18)

Abstract:
Structural vibration noise from the power compartment critically impairs the acoustic stealth performance of underwater vehicles. Utilizing vibration isolation technology to attenuate or isolate vibration transmission is an effective approach to reduce structural vibration noise. However, traditional linear vibration isolation technology struggles to achieve low-frequency vibration and noise reduction. To address this challenge, this paper proposes applying a Quasi-Zero-Stiffness (QZS) isolation method between the excitation source and the elastic structure to reduce the transmission of equipment vibration, thereby mitigating the vibration and radiated noise of underwater structures. Taking a QZS isolator coupled with a simply supported plate as the research object, the vibro-acoustic coupling equations are established and solved by considering the radiation acoustic impedance matrix with mutual coupling effects. Subsequently, the accuracy of the theoretical model is validated through finite element simulations. The results indicate that, compared to the linear isolation system, the QZS isolation system significantly reduces the initial isolation frequency and enhances low-frequency isolation efficiency. Furthermore, the introduction of QZS shifts the system's resonance frequency far below the high-radiation-efficiency volumetric control modes of the simply supported plate. This frequency mismatch mechanism effectively blocks the conversion of vibration energy into radiated acoustic energy at the source, reducing the radiated sound power by 15 dB across the entire frequency band above 10.6 Hz. This study resolves the issue of low-frequency vibration and noise reduction in underwater structures, providing a solid theoretical reference for the acoustic stealth design of power compartments in underwater vehicles.

A Study on Uncertain Vibroacoustic Characteristics of Composite Underwater Shells

LI Kexin, WANG Qingshan, ZHONG Rui

, Available online , doi: 10.11993/j.issn.2096-3920.2026-0027

[Abstract](46) [FullText HTML] (27) [PDF 3900KB](25)

Abstract:
The existing studies mostly focus on the deterministic analysis of the acoustic and vibration response of underwater composite shells, but the structural parameters, material properties and heavy fluid parameters in actual engineering are uncertain. Therefore, this paper presents an efficient prediction method based on interval analysis and agent model, which is suitable for the prediction of the vibration response of stair structures under heavy fluid environment. The research object is a composite laminated stepped cylindrical shell immersed in infinite domain heavy fluid. Based on the first-order shear deformation theory, energy method and Kirchhoff-Helmholtz integral, a vibration-acoustic coupled analysis model is established. The interval analysis method is introduced to describe the parameter fluctuation. The Kriging agent model is used to replace the time-consuming boundary element operation. The influence of various uncertain parameters on the sound pressure level response of the composite laminated stepped cylindrical shell is studied. On this basis, the deflection phenomenon of the response curve when the uncertain parameters change obviously. The results show that the multi-source uncertainty causes significant frequency shift and response fluctuation range widening. This method fills the gap of the uncertainty vibro-acoustic analysis of complex stepped structures in heavy fluid environment, and achieves the optimal balance between calculation accuracy and efficiency.

Research on Ocean Thermal Energy Conversion System Based on Supercooled Thermal Energy Storage

LU Henglin, SHA Haonan, JIANG Dongyue

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0155

[Abstract](64) [FullText HTML] (29) [PDF 3328KB](29)

Abstract:
To address the limited endurance of underwater unmanned systems such as underwater gliders (UGs), an ocean thermal energy conversion system coupling supercooled phase change materials (EPCM) with thermoelectric modules (TEM) is proposed and experimentally validated. By maintaining EPCM in a supercooled liquid state during descent and triggering spontaneous crystallization with latent heat release in cold seawater, a stable temperature difference is established across the TEM, enabling direct conversion of ocean thermal gradient energy into electrical power. Three EPCMs with different compositions and a mass of 2.5 kg were prepared, and their supercooling stability and power generation performance were evaluated under simulated sea surface–deep sea thermal conditions. The results show that the EPCM composed of 98% calcium chloride hexahydrate (CCH) and 2% PEG200 exhibits more stable supercooling and latent heat release behavior. Under deep-sea conditions, the system achieves a maximum open-circuit voltage of 15.2 V, a maximum short-circuit current of 43.06 mA, a power generation duration of approximately 2640 s, and a single-cycle energy output of 518.09 J. During a complete descent–ascent profile, the cumulative electrical energy output reaches 821.44 J, corresponding to a volumetric energy density of 547.63 kJ·m⁻³. The results demonstrate that the proposed system can provide stable energy output within a single dive cycle and shows promising potential for autonomous energy supply in underwater unmanned systems.

Applying Gradually-Varying Riblets for Drag Reduction in Conical Rotating Disk Flows

WU Sen, ZOU Jiaqi, FAN Yicheng, ZHAO Dan

, Available online , doi: 10.11993/j.issn.2096-3920.2026-0005

[Abstract](37) [FullText HTML] (22) [PDF 2458KB](22)

Abstract:
Due to structural design requirements, the front shroud of the impeller in the permanent magnet integrated centrifugal pump adopts a tapered rotating disk. However, during operation, compared to a flat disk, the tapered disk increases flow resistance and raises power consumption. To reveal the flow losses in the tapered front shroud region of the centrifugal pump impeller and explore drag reduction optimization methods, a gradually-varying riblet for drag reduction is proposed based on the drag reduction principle of uniform-sized riblets, operating under enclosed flow field conditions and optimized dynamic-static clearances. The drag reduction effect of this gradually-varying riblet was investigated and compared with those of a smooth flat disk and a disk with uniform-sized riblets. The results indicate that by adjusting its geometric dimensions along the radial direction, the gradually-varying riblet can more effectively reorganize the near-wall flow structure, alter streamline patterns and velocity distributions, thereby optimizing the wall shear stress field and achieving effective control over flow separation and turbulent dissipation. For a rotating disk with a given taper angle, arranging gradually-varying riblets on the tapered surface can reduce its drag torque below that of both the smooth flat disk and the disk with uniform-sized riblets. Specifically, at the rated speed, the torque coefficient decreases by 9.9% compared to the smooth flat disk conventionally used for current centrifugal pump impeller shrouds, and by 2.31% compared to the tapered disk with uniform-sized riblets. This study can provide a theoretical reference for the low-resistance design and performance enhancement of centrifugal pump impellers.

Experimental Study on Sailing Resistance and Attitude of Amphibious Unmanned Vehicles under Still Water Towing Conditions

ZHANG Guoqing, FENG Yikun, WANG Jiancheng, ZHANG Zhewei, XU Xiaojun

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0121

[Abstract](49) [FullText HTML] (38) [PDF 4156KB](27)

Abstract:
The still water resistance drag test is an important method for evaluating the hydrodynamic performance of amphibious vehicles. However, existing research lacked systematic description and verification of the test process and mechanism. A specific high-speed amphibious vehicle was selected as the research object. Standardized test procedures were developed using professional equipment, based on geometric parameters and predefined test conditions. Hydrodynamic performance was quantitatively measured at varying drag speeds and stern flap installation angles. Test observations and datasets were analyzed to determine the influence of speed and angle variations on sailing resistance characteristics, sinkage motion response, and trim attitude. This provided an experimental basis for hydrodynamic optimization of amphibious vehicles.

Fluid-Structure Interaction Vibration Characteristics Analysis of Thick-Walled Pressurized Fluid-Conveying Pipes

ZHU Hongzhen, WU Jianghai, SUN Yudong

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0158

[Abstract](59) [FullText HTML] (37) [PDF 1226KB](29)

Abstract:
The theoretical derivation and frequency-domain solution for axial fluid-structure interaction vibration of thick-walled fluid-filled pipes with internal pressure in marine engineering were carried out. The proposed calculation method was validated by comparison with literature examples. The applicability of thick-walled and thin-walled theories was investigated using finite element method (FEM) calculation and axial fluid pressure wave speed analysis. The effects of flow velocity and internal static pressure on vibration and noise transmission of straight pipes and assembled pipes were discussed. Results show that the thick-walled theory is more accurate for calculating the vibration response of pipes with a thickness-to-radius ratio greater than 0.5; the axial fluid pressure wave speed is mainly affected by pipe material, sectional thickness-to-radius ratio and length-to-diameter ratio; internal pressure mainly influences transverse vibration, especially lower-order frequencies, and enhances vibration transmission.

Optimization of Underwater Mapping Using EKF-FastSLAM and GPR

CUI Peng, LI Xinda, ZHANG Feihu, DU Peng

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0122

[Abstract](45) [FullText HTML] (30) [PDF 3143KB](27)

Abstract:
With the advancement of underwater exploration technologies, multibeam echo sounders(MBES) have become a key tool for underwater terrain scanning due to their efficient measurement capabilities and high spatial resolution. However, constructing high-precision maps from sonar data in complex and dynamic aquatic environments remains a significant challenge. To address the issue of particle degradation commonly encountered in traditional FastSLAM algorithms under such conditions, this paper proposes an optimized FastSLAM method based on the Extended Kalman Filter(EKF). By incorporating EKF as a proposal distribution within the particle filtering process, the method effectively integrates the latest observation data, mitigates particle degeneration, and enhances the stability and accuracy of the filter. Furthermore, considering the sparsity and lack of overlap in underwater sonar measurements, Gaussian Process Regression(GPR) is introduced to perform nonlinear modeling and map extrapolation, thereby compensating for the discontinuities in MBES-based mapping. Experimental results demonstrate that the proposed EKF-FastSLAM significantly reduces trajectory errors and improves mapping accuracy compared to standard FastSLAM. The integration of GPR further enhances the overall mapping performance. Field experiments conducted in a lake environment confirm that the proposed method achieves meter-level mapping precision.

Dynamic Obstacle Avoidance for Autonomous Underwater Vehicles via VO-PPO

ZHANG Tao, ZENG Xiangguang, LI Min, XIE Dijie, REN Wenzhe, PENG Bei

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0154

[Abstract](54) [FullText HTML] (30) [PDF 1730KB](29)

Abstract:
Efficient and safe dynamic obstacle avoidance is crucial for Autonomous Underwater Vehicles (AUV) performing military missions. To address the high collision risk and slow convergence of conventional reinforcement learning–based approaches in AUV obstacle-avoidance training, this paper proposes a dynamic obstacle-avoidance algorithm for AUV, termed VO-PPO, which integrates an improved velocity obstacle (VO) method with proximal policy optimization (PPO). In the traditional VO framework, the algorithm introduces a safety margin and a time-window mechanism to enhance the safety and efficiency of obstacle-avoidance decisions. Meanwhile, by constructing a “discrete-check–continuous-execution” safe action mask, it embeds geometric safety constraints into the policy optimization process. Combined with state-space decoupling and a multi-objective reward design, the proposed method guides the learned policy to balance safety, efficiency, and trajectory smoothness. Simulation results show that, compared with the traditional VO method, VO-PPO generates smoother obstacle-avoidance paths that better match the motion characteristics of AUV; compared with a baseline PPO algorithm, it improves the obstacle-avoidance success rate by 53%, accelerates training convergence by 67.5%, and increases the accumulated reward by 56.7%, effectively mitigating the problems of high collision risk and slow convergence.

Holt-DI-EnKF-based System for Real-time Prediction of Ocean Temperature and Salinity

ZHANG Siwen, SHI Wentao, JING Lianyou, TU Nan, WEI Chengpeng

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0149

[Abstract](53) [FullText HTML] (40) [PDF 1188KB](25)

Abstract:
To address the limitations of traditional ocean temperature and salinity prediction methods—weak dynamic update capability, distribution-dependent uncertainty quantification, and disjointed data assimilation-prediction models—this study focuses on real-time prediction of monthly average temperature and salinity time series at a single point. Aiming to develop a lightweight framework balancing accuracy, dynamic adaptability, and engineering practicality, it integrates and advances classic time series prediction, uncertainty estimation, and data assimilation methods, proposing a hybrid framework of Holt's double exponential smoothing, Bootstrap confidence intervals, and Dynamically Inflated Ensemble Kalman Filter(DI-EnKF). Specifically, the Holt model decomposes sequences and optimizes parameters, Bootstrap quantifies prediction uncertainty, and DI-EnKF assimilates real-time Argo observations to correct errors, forming a"prediction-assimilation"closed loop. Tests on global Argo data demonstrate that the framework outperforms hybrid models such as ARIMA-LSTM and ARIMA-BP in temperature prediction, with salinity prediction accuracy close to the optimal comparison model.

Energy Evolution of the Ocean Wave Spectrum and Distribution of the Induced magnetic Field Intensity

WANG Xintong, ZHANG Jiansheng, WANG Xiangjin, YAN Linbo, LAN Qing

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0134

[Abstract](49) [FullText HTML] (31) [PDF 1889KB](29)

Abstract:
The performance of marine electromagnetic detection is significantly affected by the ambient electromagnetic noise in the ocean, among which the magnetic field induced by ocean waves moving through the Earth's magnetic field constitutes a core noise source. To further investigate the formation mechanism, distribution characteristics, and patterns of this wave-induced magnetic field, this study employs the Pierson-Moskowitz wave spectrum combined with the Weaver's electromagnetic theory framework. The dynamic characteristics of a two-dimensional sea surface under varying wind speeds were simulated using the Monte Carlo random sampling method, and the wave-induced magnetic field was formulated analytically via Maxwell's equations. The research focus was to simulate the three-dimensional spatial distribution and spectral properties of the induced magnetic field under different wind scenarios. Simulation results indicate that as wind speed increases, wave evolution progresses from a low-amplitude, underdeveloped state to a complex and fully developed condition. Concurrently, the magnetic induction intensity exhibits a positive correlation with wave activity. Spectrally, the induced magnetic field demonstrates a narrowband concentration characteristic. With increasing wind speed, the dominant frequency shifts towards the lower frequency domain, accompanied by energy aggregation near the primary frequency. In the frequency band below the dominant frequency, the magnetic field intensity increases approximately linearly with frequency, while in the band above the dominant frequency, it decays exponentially with increasing frequency. The findings of this study provide theoretical and simulation support for noise modeling and signal extraction in the field of marine electromagnetic detection.

Vibration Transfer Path and Characteristic Analysis of Shaft-Underwater Conical Cylindrical Shell

ZHU Jingyao, ZHANG Cong, TIAN Yaqi

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0161

[Abstract](49) [FullText HTML] (37) [PDF 1453KB](32)

Abstract:
In order to study the transmission characteristics of the shaft-double shell structure, a fluid-solid coupling finite element model was constructed based on HyperMesh-ANSYS to simulate the dynamic behavior of the whole process of "shaft excitation-bearing transmission-shell and liquid coupling." The effects of inter-ship fluid density, bearing stiffness and fluid inside and outside the shell on vibration transmission are studied and analyzed. The results show that the inter-ship liquid reduces the resonance frequency of the system through the additional mass effect, and enhances the sound pressure level through the fluid-solid coupling. The increase of bearing stiffness suppresses shaft vibration and excites high frequency resonance of shell. In the low frequency band, the strong continuity of the inter-ship liquid enhances the vibration transmission between the double shells, while the additional mass and damping effect block the vibration transmission in the high frequency band. This study reveals the vibration transmission effect of the 'shaft-cone double-layer shell' model, and provides theoretical support for the acoustic vibration of underwater vehicles.

Research Status and Development Trends of Foreign Submarine Detection Technologies

DONG Xinxin, ZHANG Zhexuan, ZHANG Weiye

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0133

[Abstract](87) [FullText HTML] (58) [PDF 2406KB](39)

Abstract:
The primary threat of submarines stems from their concealment. In recent years, with the advancement of submarine noise reduction technologies and the intensification of electronic countermeasures, enhancing submarine detection methods and capabilities has become increasingly urgent. This paper reviews the operational characteristics (including noise, magnetic field, wake, and gravitational field) and typical combat modes of submarines, expounds on the advantages and limitations of different anti-submarine platforms and detection approaches, and summarizes the development status of detection methods (such as acoustic detection and magnetic anomaly detection) as well as representative foreign models. It analyzes the key technologies for submarine detection from three aspects: anti-jamming capability, real-time data processing and information fusion, and unmanned system collaboration and autonomous decision-making. The analysis indicates that the integration of new-type detection means with multi-source information fusion can effectively improve detection performance, while the development of capabilities like unmanned system collaboration and autonomous decision-making may serve as a breakthrough for the transformation of anti-submarine modes. This study provides valuable references for future research and development efforts in the field of submarine detection.

Latest Articles

Journal News> >

Download> >