Browse Topic: Marine vehicles and equipment

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Current Situation of Ship Navigation and Research on the Route Reform Scheme in Typical Tributary-Confluence Waters of the Lower Yangtze River2026-99-15729/11/2026
The thalweg at the outlet of the Yuxikou Waterway transitions from right to left, forming a 90-degree bend. It then merges with the Xihua Waterway after passing Xiliang Mountain, creating a main-branch confluence water area. Taking a typical main-branch confluence water area in the lower reaches of the Yangtze River as the research object, this paper reflects the current navigation status and existing problems of ships in the area through the analysis of ship traffic flow. It classifies the risk levels of passing ships, proposes suggestions for route reform and optimization, and uses a model to verify the probability of collision accidents in the area after the implementation of the round-island navigation method, providing a reference for the navigation safety of passing ships.
Liu, Ka, Xu, Yerong
Trajectory Tracking Control for UUVs Based on Deep Reinforcement Learning2026-99-11329/11/2026
Unmanned Underwater Vehicles (UUVs) operate in complex and uncertain environments, which require a suitable controller. While traditional PID controllers are widely used, they often have slow response speed and inadequate disturbance rejection, particularly under complex and uncertain conditions. To overcome these shortcomings, this paper introduces the DDPG-DLPID, an adaptive motion controller, including a Deep Deterministic Policy Gradient (DDPG) reinforcement learning that can acquire the parameters of PID controllers. In this paper, we design two loops: the inner loop handles velocity regulation, and the outer loop handles position and attitude. By using DDPG, the system can efficiently adjust the PID parameters of both loops in real time, allowing it to effectively adapt to environmental changes and achieve optimized requirements. To evaluate the controller, we design the following scenarios, including straight-line and complex path-following tasks. Compared with single-loop PID and dual-loop PID controllers, the proposed DDPGDLPID approach achieves faster response and higher tracking accuracy, while substantially reducing tracking errors under interference conditions. Physical experiments under three conditions-straight-line voyage, attitude maintaining, and depth control-were further carried out to validate the strategy’s real-world applicability. Experimental data confirm that DDPG-DLPID has better performance when compared with both traditional PID and dual-loop PID controllers across all test scenarios.
Wang, Ling, Shi, Yan
Numerical Calculation of The Ice-Breaking Resistance of the Icebreaker2026-99-15179/11/2026
This study investigates the governing characteristics of ice resistance encountered by icebreakers operating in multi-year ice regions, with particular emphasis on the effects of bow truncation length, vessel speed, and ice thickness. A numerical simulation framework was developed using the finite element platform LS-PrePost to reproduce ice bending, failure, and ship–ice interaction throughout the icebreaking process. The numerical predictions were subsequently validated against physical model test data. The results indicate that ice resistance exhibits an increasing trend as the bow truncation length, navigation speed, and ice thickness increase. The ice resistance of different bow truncation lengths in the multi-year ice area is different. By truncating the model ship at different positions from the bow and analyzing the ratio of the ice resistance of the truncated models to that of the full-scale model, researchers can better understand the effects of bow size. This can provide a theoretical basis for conducting ice resistance tests with truncated model ships in a limited-scale ice water tank, and has certain practical value for the design and optimization of the icebreaker’s hull lines.
Liu, Yanwei, Zhang, Xiufeng, Yu, Yingjie, Wang, Lucai, Zhao, Weihang
Safety-Aware Path Planning for Unmanned Surface Vehicle: An Adaptive Hybrid Collision Avoidance Operation2026-99-15249/11/2026
An adaptive performance-enhanced path planning algorithm is proposed for unmanned surface vehicle (USV) to improve their responsiveness in dynamic maritime environments. The improved ant colony (ACO) algorithm incorporates a pheromone penalty mechanism and path smoothing to enhance search efficiency and path smoothness by removing redundant nodes and reducing excessive turning. Additionally, the dynamic window approach (DWA) is enhanced through three key modifications: optimizing overshoot, enhancing selection efficiency in candidate path, and adaptively adjusting evaluation function weights. These improvements improve the accuracy of planning and avoidance ability. Comparative analysis based on simulation data indicates that the proposed method yields a measurable improvement in path quality—characterized by reduced travel length and enhanced collision avoidance—leading to more robust navigation performance in complex marine transportation scenarios.
Sun, Jiamian, Li, Weifeng
Dimensional Adaptability and Traffic Organization Analysis of Ships in Group Lockage2026-99-15109/11/2026
Aiming at the technology of electric intelligent working boat towing 4 ships in group lockage during the construction period of the Gezhouba Shipping Capacity Expansion Project, this paper, starting from ship dimensions, conducts an adaptability analysis on electric intelligent working boat towing ships in group lockage for all ships passing through Gezhouba No. 1 and No. 2 Ship Locks throughout 2024, based on the two-dimensional packing model, ship lock chamber scheduling model and algorithms, navigation scheduling rules and safety management regulations, the results show that ships unsuitable for being towed in group lockage through Gezhouba No. 1 Ship Lock account for approximately 26% of the total number of ships passing through it, while those unsuitable for being towed in group lockage through Gezhouba No. 2 Ship Lock account for approximately 57% of its total passing ships. Meanwhile, ships passing through the three Gezhouba ship locks on a specific day are selected, and an adaptability analysis on the dimensional suitability of electric intelligent working boat towing these ships in group lockage is carried out under the scenario where these ships only pass through Gezhouba No. 1 and No. 2 Ship Locks. The results show that the number of ships with suitable dimensions for group lockage accounts for the majority of the ships passing through the locks on a selected specific day. On this basis, combined with the operation modes of Gezhouba No. 1 and No. 2 Ship Locks, an analysis is carried out on the traffic organization, potential risks, corresponding countermeasures, and the required quantity of electric intelligent working boats for towing ships in group lockage, targeting the three main collaborative operation modes. The results can provide a basis for the future practical application of electric intelligent working boat towing ships in group lockage during the construction and operation periods of the Gezhouba Shipping Capacity Expansion Project.
Huang, Shaowen, Yang, Xi, Wang, Jian
Exploration of the Minimum Safe Transverse Distance for Ships Passing Through the Pier of Huangpu River Tidal Barrier Based on the Boundary Element Method2026-99-15469/11/2026
The Huangpu River tidal barrage is in a navigable reach where the quay wall greatly restrains the flow. Earlier studies focused on ship-structure interaction, but there aren’t many hard numbers on safe passing distance near the barrage pier. The purpose of this paper is to determine the lowest safe lateral gap for large vessels and to provide an engineering means of ascertaining the clear width of the main channel. A 20,000-ton oil tanker is used as the test vessel. Using the boundary element method (BEM), a 3D model is constructed to simulate the interactions between the ship and the pier under varying speeds, draft depths, and lateral offsets. Simulations were conducted for different speed levels, draft depths, and lateral offsets to observe the flow and the ship’s movement. Changes in side forces, yawing moments, and bow angles were recorded over time, and their maximum values were determined. Sensitivity and uncertainty analyses were also performed to evaluate how input variations affect the results and to assess model stability. Based on these results, simple limits were established for the three measures to serve as safety rules. Using these rules, the clear width of the main channel was calculated. The results indicate a minimum safe lateral distance of 14 m and a suggested channel width of 202 m, deviating by only 0.5 m, or approximately 0.25%, from the theoretical value of 202.5 m. These findings can also be applied in practice for pier layout and the determination of speed limits in narrow channels.
Guan, Keping, Yu, Min, Zhan, Qingan
Experimental Study on Partitioned Fruit and Vegetable Storage in Ships2026-99-15039/11/2026
After an investigation into a fruit and vegetable storage compartment on a ship, this paper proposes a method for creating different temperature zones within a single storage unit. To perform this approach, a top perforated plate air supply system should be implemented, and storage panels should act as partitions to make temperature control more accurate in different zones within the same compartment. This method ensures that fruits and vegetables can be stored for the best flavor at suitable temperatures, enabling fewer separate storage units on the ship. According to the experimental results, this solution can preserve various types of fruits and vegetables under different conditions during long trips, deal with the challenge of chilling or freezing injury due to mixed storage, and save the cold storage capacity on the ship. The proposed method has significant value in engineering applications.
Xie, Zhihao, Cui, Yonglong, Duan, Wenli, Li, Kun, Li, Qi, Wei, Shuaiju
A Maritime Occluded Ship Detection and Tracking Method Based on Improved YOLOv8 Fused with AIS Trajectory2026-99-15499/11/2026
Typical maritime monitoring scenarios are usually constrained by factors such as multi-scale ship density, frequent motion overlap, and limited viewing angle of shore-based cameras. These challenges often lead to trajectory interruptions and identity mismatches in target detection and multi-target tracking tasks. In order to solve these problems, this study proposes a ship occlusion detection and tracking method based on the improved YOLOv8 model and further integrates an automatic identification system (AIS) trajectory reasoning. The method builds a unified perception framework with enhanced detection architecture, multi-source data fusion, and behavioral reasoning capabilities. First, in the target detection module, the improved SEConv structure is introduced into the YOLOv8 trunk network to address challenges caused by small-scale variations and severe occlusion in maritime scenes. The ReLU activation function in SEConv is replaced by the Swish activation function to enhance the nonlinear feature representation. In addition, the optimized SEConv is embedded in the C2f structure, and the convolutional block attention module (CBAM) attention mechanism is introduced to enhance the sensitivity of the model to the occlusion area. Next, for multi-target tracking, ByteTrack is used as the basic tracking framework. AIS trajectory data is introduced as auxiliary input to compensate for trajectory losses caused by occlusion. Finally, experimental results on the SeaShips public dataset and the self-built occlusion reference dataset show that the improved YOLOv8 detector achieves stable mAP gains in mild, moderate, and severe occlusion scenarios. The AIS enhanced tracking system improves the multi-target tracking accuracy (MOTA) and identification F1 score (IDF1) by about 6.3% and 8.1%, respectively, and the average occlusion reconstruction error is controlled within 1.4 seconds. The proposed method effectively enhances the perception ability of ships in complex occlusion environments and verifies the feasibility and superiority of the strategy of combining visual detection with AIS data assistance.
Guan, Keping, Chen, Miao, Zhou, Yue
A Simple and Efficient THINC Scheme for Multiphase Flow via Dominant-Material Selective Reconstruction2026-99-12299/4/2026
Multiphase compressible flow problems are widespread in aviation, aerospace, transportation, military, and industrial fields, for instance, in underwater explosion bubble dynamics, fuel injection for hypersonic vehicles, liquid sloshing in propellant tanks, and supercavitating underwater vehicles. This paper proposes an improved THINC (Tangent of Hyperbola for Interface Capturing) method for multiphase flow simulations, based on a selective reconstruction strategy for the dominant material. The core of the strategy is to apply the THINC reconstruction exclusively to the material with the largest volume fraction within a multiphase mixed cell, which numerically governs the local interface evolution. The volume fractions of non-dominant materials are then obtained through a proportional distribution that inherently ensures the summation (Σαk = 1) and boundedness (0 ≤ αk> ≤ 1) constraints are met without explicit corrections. This approach reduces the number of THINC reconstructions for each time step in a multiphase mixed cell from Nm (the number of materials) to one, significantly simplifying the algorithm and lowering computational cost. It thereby avoids the error accumulation and complex renormalization procedures associated with conventional schemes that reconstruct all materials. While strictly maintaining volume fraction conservation, the proposed method preserves interface sharpness through the underlying THINC framework. The method is implemented in a diffuse-interface, multiphase Eulerian framework and validated with a series of challenging benchmarks, including shock-helium bubble interaction, triple-point problem, gas impact, and the more complex modified gas impact. Numerical results show that, compared with conventional multiphase THINC approaches that reconstruct every material, the proposed scheme can reduce CPU time by about 40.0% without compromising the accuracy of key physical quantities.
Wang, Wei, Zhong, Yanxu, Hu, Qinghua, Yang, Canqun
Numerical Study on Measurement Accuracy of Liquid Level/Capacity Measurement Device and System in a Shipboard Environment2026-99-01227/31/2026
In the marine environment, navigation safety and operational effectiveness depend heavily on the precision of liquid level/capacity measurement equipment and systems. In order to examine their measurement accuracy under complex operational situations, including ship navigation states and water tank sloshing, this study employed computational fluid dynamics (CFD) methodologies. The numerical technique performs a thorough examination of how various operating conditions impact measurement accuracy and integrates the volume of fluid (VOF) model and laminar flow model with appropriately defined boundary conditions and solver settings. The findings indicate that constant-speed navigation has minimal impact on accuracy, horizontal acceleration causes moderate deviations, and accelerated diving greatly reduces precision. The amplitude of water tank sloshing has a positive correlation with measurement error. When sloshing amplitudes are less than 1 m, the integration of the resulting acceleration efficiently lowers deviations while preserving excellent accuracy. In light of these results, we advise adding accelerometers to differential pressure transmitters to improve measurement precision. This investigation provides data-driven references and technical solutions for system design and operational standard formulation in marine measurement systems.
Shang, Jin, Qin, Ziming, Wang, Yingwei, Wu, Chao, Zhao, Fenggang, Chen, Liang, Xia, Wei, Yan, Jin, Chen, Min, Chen, Guoao
Multi-Objective Optimization Design of Ship Propulsion Shaft System in Ice Area Based on NSWOA Algorithm2026-99-01527/31/2026
Ship propulsion shaft systems are subjected to ice load excitation when ships are navigating in polar ice regions. Compared to conventional hydrodynamic effects, the ice load imposes higher requirements on the shaft system’s ability to withstand torsional stresses. To improve the power of the ship propulsion system when sailing in ice areas and reduce the power loss of the shaft system, while considering the vibration performance. In this paper, a multi-objective optimal design of the shaft system is carried out using the Non-dominated Sorted Whale Optimization Algorithm (NSWOA) to reduce stresses on both the motor shaft and the intermediate shaft. The coupled system model of motor-shaft system-propeller structural components is established, and the system dynamics response model is obtained by solving using the Newmark-β method. Based on the response model, a multi-objective whale optimization algorithm is used to optimize the power and vibration performance of the shaft system simultaneously. The optimized results show that the shaft system transfer efficiency is improved by 0.27%, and the stress at the shaft end is reduced by 11.8% and 12.3% respectively.
Hu, Chuanxi, Li, Yao, Pan, Shuxian, Liu, Zhiyong, Xie, Yuteng, Ye, Jun, Zhou, Ruiping
Simulation Research on Non-Destructive Testing of Pipeline Based on Ultrasonic Guided Wave2026-99-01437/31/2026
Ultrasonic guided waves enable long-range, low-intrusion inspection of pipelines. This study examines how array topology and axial spacing influence the quality of defect echoes when the longitudinal axisymmetric mode L(0,2) is used. We build COMSOL finite-element models of a steel pipe and excite it with PZT-4 at 80 kHz; three practical layouts are compared: (i) odd–even receiving, (ii) 8-transmit/8-receive, and (iii) 16-transmit/8-receive, arranged as two axially separated groups. The spacing between the groups is chosen to suppress parasitic modes such as L(0,1) and to strengthen L(0,2). Results show that the two-group configuration sharpens the defect echo and reduces modal interference; increasing the number of transmitters further raises the defect-wave amplitude and improves the separation from end-reflection echoes. Among the schemes, 8×8 performs well for small-defect identification, while 16×8 yields the clearest boundaries and fastest defect indication. These findings clarify how sensor number and placement govern modal purity and sensitivity, and they offer practical guidance for designing guided-wave arrays that improve the reliability of long-range pipeline inspection. - Ultrasonic guided waves Pipeline non-destructive testing L(0,2) mode; Sensor array layout; Finite element simulation; Guided wave signal processing.
Liao, Wei, Li, Tengfei, Zhang, Wenhui, Lin, Qingming, Guo, Yanbing
Study on the Adaptability of Underwater Propeller-Driven Bernoulli Adsorption Device on Irregular Walls2026-99-01727/31/2026
The propeller-driven Bernoulli adsorption device (PBD) has both propulsion and adsorption functions, being suitable for dual-mode underwater robots. Currently, there have been studies on the adsorption performance of PBD on the flat surface. However, the surface morphology of underwater engineering structures is different, and PBD’s adsorption performance on irregular walls still remains unknown. In this letter, based on the potential application scenarios of underwater dual-mode robots, we established four types of irregular wall models to investigate PBD’s adsorption performance on irregular walls. Through CFD simulations and experiments, the adsorption state was analyzed, and the adsorption performance was quantitatively studied.
Liu, Siyue, Hua, Zhong, Yang, Canjun
Enhanced Vibration Damping Properties of Novel Mn-Cu Alloy for Ship Structural Applications2026-99-02367/31/2026
Low-frequency vibrations in ships have detrimental effects on the lifespan of onboard equipment and the comfort of crew members, thereby highlighting the importance of developing efficient vibration-damping materials as a critical research area. This study investigates the application of Mn-Cu damping alloys for mitigating vibrations within the 0–1000 Hz frequency range, which is typical of ship environments. The vibration-damping characteristics of the material were examined through a combination of experimental and numerical simulations. A numerical simulation framework was developed to predict the vibration response of manganese-copper damping alloys, incorporating a frequency-dependent damping ratio model derived from experimental characterization. Comparative analyses validated the accuracy of vibration simulations that incorporate frequency-dependent damping ratios and demonstrated the superior vibration attenuation performance of the Mn-Cu damping alloy across the 0-1000 Hz frequency band. Deck application analysis revealed that manganese-copper damping devices reduced the root mean square (RMS) vibration acceleration of the ship deck by up to 17.5% in the 0-1000 Hz frequency range compared to aluminum alloy counterparts. The damping effect was particularly significant in the 400–1000 Hz range, where vibration energy dissipation was most effective due to the material's intrinsic damping mechanisms. Additional engineering evaluation confirmed that the Mn-Cu alloy components maintain structural integrity while providing enhanced damping performance under typical marine environmental conditions. This study establishes a theoretical foundation for the design of ship vibration-damping materials, expands the potential applications of damping alloys in marine engineering, and provides valuable reference data for material selection and vibration control design in shipbuilding and offshore engineering applications.
Yao, Sitong, Tian, Ali, Zhao, Xianghua
Topology Optimization of Lightweight for Frame Structure of Deep-Sea Mining Vehicle2026-99-01307/31/2026
In order to improve the self-sufficiency rate of key mineral resources in China, it is necessary to develop and research deep-sea mining vehicles to improve the mining capacity of seabed mineral resources. The deep-sea mining vehicle is a heavy-duty underwater robot, and its main frame structure, as a critical component, must be designed to be lightweight to improve payload capacity and mining efficiency. This paper first conducted static analysis for the initial main frame structure. Finite element analysis results indicate that the initial structure fails to meet the strength requirements for lifting and recovery operations. The power index penalty factor was introduced into the topology optimization, which was based on the variable density method. The topology optimization objective was set to minimize structural compliance, with the maximum element stress and volume fraction used as constraints. The optimization process finally obtained the optimal material distribution. According to the results of topology optimization and space requirements of the installed equipment on the deep-sea mining vehicle, the new frame structure of the mining vehicle was re-established in the secondary modelling. According to the results of the analysis, the weight of the frame structure was reduced by 2.9%, and at the same time, the maximum stress was reduced by 57.2%, the maximum displacement was reduced by 47.2%, and the first-order natural frequency was increased by 54%. The strength and stiffness of the frame structure were greatly improved.
Tao, Yichun, Yang, Mingyu
Research on Ultrasonic Measurement Technology for Submarine Pipeline Deformation2026-99-02237/31/2026
Aiming at the measurement of buckling deformation defects of submarine pipelines in turbid waters, a precise measurement method for submarine pipeline deformation was proposed based on ultrasonic ranging technology. A unified underwater coordinate system for submarine pipelines and measurement sensors is established, and a three-dimensional model of the pipeline outer surface is constructed on this basis to provide a basis for calculating pipeline deformation elements. On the basis of underwater ultrasonic velocity correction, measurement accuracy control measures were proposed. Two types of ultrasonic measurement transducers and measurement systems were designed, and engineering applications were carried out to measure the deformation of submarine pipelines in the project. The measurement results indicate that the ultrasonic measurement system operates well under harsh sea conditions such as high turbidity, low visibility, and high flow velocity in the construction sea area, with high measurement accuracy. The three-dimensional model of the deformed pipeline is constructed accurately, and the deformation characteristics of the pipeline can be accurately calculated, meeting the requirements of engineering applications and providing effective data support for submarine pipeline maintenance.
Wang, Kekuan, He, Yazhang, Wang, Hong, Zhang, Tao, Cheng, Peiliang, Sun, Xinyan, Bai, Qian
Research on Integrated Design and Optimization Method of High Speed Shuttle UUV Rudder and Propeller2026-99-08647/30/2026
Along with the advancement of the maritime power strategy, the research, development, and application of deep-sea space stations are becoming increasingly important. However, since deep-sea space stations mainly rely on acoustic communication, they cannot exchange information with ground stations quickly and accurately. To improve data transmission efficiency, this paper proposes using a high-speed shuttle UUV instead of acoustic communication. In this context, an efficient propulsion system is critical as it enables the UUV to achieve high speed and maintain stability. A propeller meeting the 110.9 N thrust requirement is designed using the chart design method, and the 110BL230-630 brushless DC motor is selected based on motor–propeller matching. This motor has a rated speed of 3000 rpm, rated power of 3000 W, and torque of 9.6 Nm. The performance curve of the NACA0012 airfoil is analyzed to select an appropriate rudder surface. The rudder area (4067 mm^2) is designed in accordance with DNV rules, with the following parameters: tip chord length 40 mm, root chord length 40 mm, and half-span 70 mm. CFD analysis is conducted on the designed propeller and the UUV equipped with the integrated propulsion system. The predicted performance of the P4119 propeller (hydrodynamic parameter deviation ≤ 1%) and the SUBOFF hull (resistance relative error ≤ 3.04%) confirms the accuracy of the CFD method for calculating propeller open-water performance and UUV drag. Through comparative analysis, the optimal rudder–propeller spacing is determined to be 60 mm, as this spacing yields the highest propulsion efficiency.
Wei, Jiaguang, Feng, Xiaowei, Zhao, Fuchen, Wang, Xingke, Xu, Shanzhi, He, Wenxuan
Design of an AUV Recovery System Based on a Cable-Based Cable Reduction Device2026-99-08687/30/2026
With the continuous advancement of marine technology and growing humanity’s demand for ocean exploration, autonomous underwater vehicles (AUVs) have been widely deployed. Consequently, the safe, efficient, and accurate recovery of AUVs has become a significantly important research issue. To address these challenges, this study proposes an AUV recovery system utilizing a Cable-based roll reduction device. Based on existing marine crane equipment, the crane design is modified to incorporate this roll reduction mechanism. A three-dimensional model and kinematic model of the recovery system were established for analysis. MATLAB-based simulation analysis examined the forces and motion states under wave disturbances. A novel recovery cage was designed, modeled in SolidWorks, and subjected to finite element analysis to verify structural strength and validate design rationality. Final results demonstrate that this device significantly reduces recovery system sway, substantially enhances AUV retrieval accuracy, and provides a novel approach for AUV recovery.
Wu, Tian, Cheng, Zhaoyang, Li, Tianyi, Zhao, Lei, Kang, Xiaogang, Wa, Jianli, He, Yunpeng
Optimization of Turbine Discrete Noise by Non-Uniformly Distributed Blade Design2026-99-16177/24/2026
The Mellin non-uniformly distributed moving blade method was adopted to conduct CFD numerical analysis and sample experimental tests on the axial-flow turbines before and after optimization using the uniformly distributed and non-uniformly distributed design methods, respectively. In the original design, five blades were evenly distributed in the 360° circumferential direction, and the non-uniformly distributed angles were 46°, 102°, 46°, 83°, and 83°. CFD numerical analysis shows that due to the low rotational speed of the turbine and the absence of a sealing structure at the blade tip, factors such as tip noise leakage and backflow have little impact, and the flow field pulsation is mainly caused by the blades themselves. The non-uniformly distributed design can significantly enhance the work-doing capacity of the blades. At 90% of the blade height, the torque can be increased by up to 60%, but at the same time, the axial force on the blades also increases accordingly. Near 80% - 90% of the blade height, the axial force increases by 33%. The flow rate performance of the non-uniformly distributed design is slightly inferior to that of the uniformly distributed design, but the overall noise is better than that of the uniformly distributed design, with maximum optimization of 0.48 dB (A); the maximum values of the first three orders of discrete noise are significantly improved, with a maximum improvement of 0.75 dB (A), and the discrete noise orders of the non-uniformly distributed turbine can avoid blade - related factors and disperse the energy to nearby orders.
Wu, Aiping, Ma, Tianli, Wang, Shiming, Ding, Chengling
Biomimetic Design and Numerical Analysis of a VIV Suppression Fairing for Offshore Risers2026-99-16407/24/2026
As oil and gas exploitation advances into deep seas, risers linking offshore platforms and subsea extraction systems endure long-term complex marine loads. Fatigue damage from Vortex-Induced Vibration (VIV) has become a key factor limiting the safe operation of deep-sea engineering structures. To address this issue, a bionic adaptive rotating fairing, which is adjustable to ocean current directions, was designed. Its main components include buoyancy blocks, a fairing with spiral guide rails on the inner wall, and clamps, which work together to reduce VIV by regulating flow patterns. Numerical simulations of concave and convex fairings showed that under subcritical flow, shifting from a concave to convex cross-section gradually enhances the fairing’s drag and lift reduction effects on risers, with a steady improvement trend. Further comparisons were made between 0.25D convex fairings, 0.35D convex fairings, and bare risers, focusing on drag/lift reduction, vortex shedding frequency, and Strouhal number. Both convex fairings exhibited similar VIV suppression performance to the bare riser, but differed significantly in the percentage reduction of vortex shedding frequency and Strouhal number. Thus, the 0.25D convex fairing was identified as the optimal configuration for VIV suppression among the concave-convex fairings studied.
Zhang, Xu, Song, Guangming, Wang, Baozhong, Zhao, Jinpeng, Chen, Qianshuo
Study on Resistance and Surface Pressure Characteristics of UUVs Navigating in the Pycnocline2026-99-18077/17/2026
As a critical component of unmanned naval warfare, Unmanned Underwater Vehicles (UUVs) have garnered significant attention from major military powers. When navigating through pycnoclines—a widespread vertical density stratification in marine environments—UUVs generate volume effect internal waves that influence hydrodynamic resistance. Therefore, investigating the hydrodynamic characteristics of UUVs in pycnoclines is essential. Despite substantial research progress, most studies focus on internal wave patterns and their impacts on submerged vehicles, with limited exploration of UUV resistance and surface pressure distribution. This work establishes a numerical method according to the Reynolds-Averaged Navier-Stokes (RANS) equations, employing the Realizable k-ε turbulence model and the Volume of Fluid (VOF) method to capture fluid density interfaces, thereby analyzing the hydrodynamic characteristics of UUVs in pycnoclines. Furthermore, a numerical method was constructed, and the convergence regarding the grid and time-steps were verified. Additionally, numerical experiments under varying navigation speeds and depths are conducted to investigate the total resistance, frictional resistance, wave-making resistance coefficients, and spatial variation of surface pressure. Based on the results, the total resistance of a UUV is positively correlated with its navigation speed. When navigating in the upper seawater layers, the total resistance also exhibits a positive correlation with navigation depth. However, when operating in the lower seawater layers, the total resistance initially increases and then decreases with increasing depth, reaching its peak level at a navigation depth of 13 m. Both increasing navigation speed and approaching the density interface can enhance the sensitivity of total resistance to navigation depth. The alteration in total resistance stems primarily from changes in wave-making resistance while showing a weaker correlation with frictional resistance. The UUV’s speed positively correlates with pressure at locations with abrupt curvature changes on its surface, but it has a negligible influence on pressure distribution in smooth surface regions. Besides, navigation depth positively correlates with surface pressure magnitude yet exerts a limited impact on pressure distribution patterns. The findings contribute to a more complete picture of the hydrodynamic properties of UUVs navigating through pycnoclines, offering valuable references for optimizing UUV design and operational strategies.
Zhang, Yin, Xue, Leilei, Guo, Liqiang, Fu, Xiao, Zhang, Xiaofang, Liu, Zhihao, Han, Guoxin
Design of Carrier-Based Aircraft Landing Control Law Based on First-Order Linear Active Disturbance Rejection Control2026-99-18357/17/2026
This paper investigates the high-precision landing control problem of carrier-based aircraft. An Active Disturbance Rejection Control (ADRC) technique is employed to design longitudinal and lateral-directional landing control laws. The landing process is simulated by incorporating an airwake model, and the results are compared with those of a PID control law. The analysis demonstrates that the proposed ADRC controller reduces lateral deviation errors and significantly improves landing accuracy and success rate.
Yu, Jiayang, Yin, Yong
Hydrodynamic Analysis of Amphibious Aircraft Stability during Water Taxiing2026-99-18307/17/2026
When an amphibious aircraft is taxiing on a wavy water surface, the force of the water directly concentrates on the floats, directly affecting the stability of the aircraft’s taxiing process. The vortices generated by the wave undulations exert significant hydrodynamic forces on the floats, thus impacting the stability and maneuverability of the float’s taxiing process. This study uses CFD numerical simulation to simulate the float’s taxiing process on a wavy water surface. By comparing the pressure distribution and vortex contours of the float under different wave height parameters, the effect of wave height on the hydrodynamic mechanism can be elucidated. The results show that the effect of wave height on aircraft stability is closely related to the position of the impact point when the wave crest hits. At a wave height of 0.5 meters, if the impact point is close to the center of gravity, it can lead to instability of the aircraft. These conclusions provide an important theoretical basis for the design and optimization of amphibious aircraft floats.
Zhang, Feifan, Li, Zhandong, Zhao, Jinfang, Kong, Fanwei, Qu, Ligang
Enhancement of Tractive Trafficability for a Four-Track Unmanned Amphibious Tracked Vehicle2026-99-05787/10/2026
This study addresses the insufficient tractive trafficability of four-track unmanned amphibious tracked vehicles (UATV) in beach terrain by proposing an optimization strategy based on coordinated suspension height and hitch point adjustment. A mathematical model of vehicle drawbar pull was established to systematically analyze the influence mechanisms of vertical load distribution, suspension adjustment, and hitch point elevation on tractive trafficability. DEM-MBD coupling simulations revealed differentiated traction laws under sandy loam and clay conditions, particularly regarding track overlap effects. Results demonstrate that in sandy loam, rear-axle traversal over front-axle tracks reduces drawbar pull due to soil loosening, whereas track overlap enhances drawbar pull in clay through soil compaction. Nine suspension-hitch configurations were tested, validating optimization strategies: increased front-axle loading (Configuration a) in sandy loam and reduced front-axle loading (Configuration f) in clay. These configurations significantly improved tractive trafficability.
Chen, Yaoyao, Gao, Xue, Wang, Wenhao, Xu, Xiaojun
Research on the Construction Scheme of Offshore Approach Embankment Based on Marine Environmental Elements2026-99-17075/22/2026
Based on the measured hydrological and meteorological data of Pikou Port Area, this paper adopts the numerical simulation method to analyze the impacts of different construction schemes of the approach embankment on the hydrological dynamics and scouring and silting environment in the project area. The results show that the flow velocity increases and the sedimentation rate decreases at the head of the approach embankment and in the permeable area, while the flow velocity decreases and the sedimentation rate increases on both sides. Through comparison, it is found that during the flood tide peak, the variation range of the flow velocity in Scheme One is 4.45 km2, slightly larger than that in Scheme Two; during the ebb tide peak, the variation range of the flow velocity in Scheme One is 13.87 km2, smaller than that in Scheme Two; and the variation range of scouring and silting in Scheme One is 2.55 km2, smaller than that in Scheme Two. From the perspectives of berthing stability and long-term maintenance, selecting a non-permeable approach embankment for the offshore segment is more appropriate. Based on the comprehensive judgment, Scheme One is superior.
Fei, Chengpeng, Chen, Mingbo, Zhou, Fang, Wang, Shiyue, Zhou, Siyang, Zhang, Fang
Risk Assessment of Bunkering Process for LNG River Powered Ship2026-99-17225/22/2026
At present, with the rapid development of LNG powered ships, China’s LNG powered ships have formed a certain scale, but the speed of infrastructure construction such as bunkering stations restricts the development of LNG powered ships. In this process, “tank truck-to-ship bunkering”(TTS) has become one of the most widely used bunkering methods in China because of its flexible, fast and convenient characteristics, but there are many hidden dangers in the bunkering process. According to the characteristics of TTS, fault tree method is used to identify the risk of bunkering process, and the leakage of pipeline system is listed as the basic risk factor. The leakage probability of different aperture is analyzed by industry statistics. Three different leakage scenarios are selected and the consequences are simulated by PHAST software. The study shows that the failure of the valve and flange can easily lead to the leakage of LNG in the TTS process, and the leakage of the medium aperture and the full aperture will form the liquid pool, so some measures should be taken for the protection.
Dong, Yuanchao
Small Craft - Marine Propulsion Engine and Systems - Power Measurements and DeclarationsJ1228_202605 (Current)5/7/2026
This SAE Standard specifies the test requirements in addition to those given in ISO 3046-1 for determining the power, at a single point or as a power curve, of marine propulsion engines or systems for recreational craft and other small craft using similar propulsion equipment of less than 24 m length of the hull. It also provides the means for documenting and checking the declared (rated) power published by the manufacturer.
Marine Technical Steering Committee
Hose and Hose Assemblies for Marine ApplicationsJ1942_202605 (Current)5/6/2026
SAE J1942, developed through the cooperative efforts of the U.S. Coast Guard and SAE, became effective August 28, 19911, as the official document for nonmetallic flexible hose assemblies for commercial marine use. This SAE Standard covers specific requirements for several styles of hose and/or hose assemblies in systems aboard commercial vessels inspected and certificated by the U.S. Coast Guard. It is intended that this document establish hose constructions and performance levels that are essential to safe operations in the marine environment. Refer to SAE J1273 for selection, installation, and maintenance of hose and hose assemblies. Refer to SAE J1527 for hose to convey gasoline or diesel fuel aboard small craft, including pleasure craft and related small commercial craft regulated directly or by reference under 33 CFR 183 Subpart J, and boats and yachts meeting American Boat and Yacht Council standards. SAE J1942-1 is a listing of the products which have been certified for use in the applications described in SAE J1942, Table 1, for fluid power, fuel oil, lube oil, water, and pneumatic systems. SAE J1942-1 is updated yearly and is available from SAE as a single copy document.
Hydraulic Hose and Hose Fittings Committee
Saving Lives at Sea and on LandTBMG-551675/6/2026
A boat can sink in under a minute, stranding passengers miles from land and leaving them virtually invisible amid the vast expanse of water. Survival can depend on emergency supplies such as a personal locator beacon (PLB) and emergency position-indicating radio beacon (EPIRB) to alert search and rescue teams. When a competitive fishing trip went wrong for Easton Barrett and his friends 40 miles off the Gulf Coast of Mississippi in 2024, a PLB helped the U.S. Coast Guard rescue the people clinging to coolers and treading water after being head-butted by sharks.
Survivability, Lethality, and Mobility Requirements of Military Vehicles Conducting Future Wet-Gap Crossings2026-01-02644/7/2026
Wet-gap crossings, which involve moving military forces across rivers and other water obstacles, remain among the most difficult operations to plan and execute. These maneuvers are complicated by choke points, fast-flowing water, and the exposure of forces and equipment to enemy fire. Despite these challenges, wet-gap crossings are critical to maintaining operational momentum during large-scale combat operations. This study examines doctrinal approaches to wet-gap crossings and explores the relationship between these operations and observed vehicle losses in the Russia-Ukraine War. Using a mixed-method approach, the analysis integrates daily operational reports from the Institute for the Study of War with visually confirmed equipment loss data from Oryxspioenkop. A custom Wet-Gap Relevance Score (WGRS) was developed using Natural Language Processing techniques to quantify the degree to which each ISW report focused on crossing operations. Statistical analysis shows that pontoon losses cluster within two days of major crossing events, confirming long-standing engineering doctrine regarding the vulnerability of bridging assets. However, the overall correlation between WGRS scores and total daily vehicle losses is weak, suggesting that broader attrition patterns obscure the distinct impact of crossing operations. These findings provide new empirical insight into how doctrinal principles manifest in modern conflict and underscore the design implications for future military vehicles. Effective wet-gap crossings require a diverse fleet: amphibious vehicles to establish bridgeheads, light vehicles that can be rafted to sustain momentum, and heavier vehicles that depend on bridging to continue the assault.
Lynch, Benjamin, Dosan, Logan, Mittal, Vikram
EP40: Structural Epoxy Used for Steel Bonding in Marine Applications26AERP04_074/1/2026
Master Bond EP40 is a two-part, room temperature curing epoxy for bonding, sealing, coating, and encapsulating. EP40 bonds well to a variety of substrates, including naval steel, the primary structural metal used in the shipbuilding industry. Master Bond Inc., Hackensack, NJ To reduce its environmental impact and pollution, the shipping industry is investigating methods to construct more lightweight ships. One potential method is using adhesive bonding techniques to replace traditional welding and riveted joints on ships to fabricate lighter ships with smaller carbon footprints. However, adhesives age and deteriorate when exposed to moisture, high temperatures, and ultraviolet light. This makes it necessary to understand how they age in maritime environments to determine whether they can truly replace traditional welding techniques. To this end, researchers at Centro de Investigación en Tecnologías Navales e Industriales (CITENI) and Centro de Investigación TIC (CITIC) developed a new method for studying adhesive aging on naval steel substrates. Master Bond EP40 was selected as the test adhesive for this method due to its strong performance and suitability for marine conditions. By using EP40, the team ensured that the observed adhesive bonding behavior would reflect a high-quality epoxy's potential in ship structures. The goal was to evaluate how EP40 bonds to naval steel and how the bulk epoxy material would behave in seawater to provide insights into the construction of lighter ships using this approach.
Undetectable Ship-to-Ship Laser Communications26AERP04_064/1/2026
Astrolight recently demonstrated undetectable, unjammable, and high-bandwidth laser-based ship-to-ship communication with its POLARIS terminal during REPMUS'25, NATO's largest unmanned maritime exercise. During the Robotic Experimentation and Prototyping using Maritime Uncrewed Systems (REPMUS) /Dynamic Messenger mission, hosted by the Portuguese Navy, POLARIS laser terminals maintained a stable, jam-proof horizon-limited laser-based link between two vessels: NRP Dom Francisco de Almeida and NRP Dom Carlos I. During testing, the link wasn't detected by a single sensor of other participating ships, drones, and land assets.
Autonomous Undersea Gliders for Anti-Submarine WarfareTBMG-549144/1/2026
Bio-Inspired Robotic Wing Enhances Underwater Vehicle ControlTBMG-548954/1/2026
Researchers have taken inspiration from nature to create a robotic wing that can sense and adapt to changes in water to deliver unparalleled stability.
Effects of Salt Spray Corrosion on Thermal Runaway of Lithium-ion Batteries2026-01-70312/27/2026
The increasing electrification of marine equipment underscores the need to ensure lithium-ion battery (LIB) safety in corrosive environments. Unlike land applications, shipboard batteries are continuously exposed to salt spray, which accelerates material degradation and raises the risk of thermal hazards. Thus, this study investigates the effects of salt spray corrosion on the electrochemical performance and Thermal runaway (TR) behavior of commercial 18650-type ternary LIBs. Through charge-discharge calorimetry and cone calorimeter tests, variations in voltage response, capacity fade, mass loss, and heat release rate were analyzed under different states of charge (SOC), states of health (SOH), and exposure durations. The results show that corrosion significantly accelerates electrode deterioration, leading to faster capacity decline and voltage plateau shifts. At higher SOH, casing rupture induced earlier TR with violent combustion, whereas at lower SOH, corrosion-induced energy depletion delayed onset and reduced flame intensity. Mass loss increased with decreasing SOH, while the effective heat of combustion remained relatively stable. Thus, salt spray intrusion can cause damage to the internal structure of the battery, inhibit electrochemical reactions, and significantly reduce the operational function, thereby bringing potential safety risks.
Tao, Liyanyu, Shi, Xinyuan, Yang, Qinyuan, Liu, Jiahao
Design and Performance Study of Highly Reliable Marine Battery Based on Solid Polymer Electrolyte2026-01-70352/27/2026
Currently, electric propulsion is playing an increasingly important role in marine propulsion systems.Lithium metal batteries are new-generation high-performance energy storage system with development prospect. Traditional flammable and volatile organic liquid electrolytes pose a risk of thermal runaway, while solid-state lithium metal batteries using solid electrolytes have significant advantages in energy density and safety, and are considered the most promising mobile power sources. Among numerous solid electrolyte systems, polymer solid electrolytes have excellent flexibility, good interface compatibility, and good processing characteristics, which have attracted the attention of researchers. Polyurethane (PU) is a common polymer with high mechanical strength and a flexible and adjustable molecular structure, making it one of the best choices for polymer electrolyte matrices. Based on the structural design of polyurethane polymers, this paper explores polycaprolactone type polyurethane electrolyte and the effect of high dielectric constant polycaprolactone on the dissolution and dissociation of lithium salts was studied. We found that polycaprolactone, as the soft segment, exhibits greater electronegativity and provides more oxygen atoms for coordination with lithium ions, which is crucial for enhancing lithium ion transport and improving ionic conductivity.The prepared PU-based solid polymer electrolyte has a conductivity of up to 2.4 × 10-4S/cm, lithium ion migration number 0.78, electrochemical stability window 4.74V. The tensile strengths of PU-based solid polymer electrolyte can reach 2.36 MPa, that balance ionic conductivity and mechanical strength.Besides, it also possesses excellent thermal stability.The symmetrical battery assembled based on the prepared PU-based solid polymer electrolyte exhibits excellent cycling stability (400 hours). The assembled solid-state lithium metal battery based on LiFePO4 can stably cycle for 200 cycles at a current density of 1C, with a Coulombic efficiency of over 99% and a capacity retention rate of up to 99.4%, demonstrating exceptional reliability.
Yuan, Meng, Tang, Qing, Yu, Gongye
Lightweight Design and Optimization of Multi-Terrain Multi-Functional Tracked Amphibious Vehicle2025-99-032412/17/2025
In view of the complex intertidal terrain challenges faced by offshore wind power maintenance, this paper optimizes the lightweight design of multi-terrain tracked vehicles. The structure was optimized by finite element analysis, and the maximum stress was 211.68 MPa ( lower than the safety limit of 230 MPa), and the maximum deformation was 5.25 mm, which ensured the stability and stiffness. Titanium alloy has the advantages of high strength, low density and corrosion resistance, which improves the durability of the frame while reducing the weight of the frame. Advanced manufacturing technologies such as phase transformation superplastic diffusion welding optimize the connection between TC4 titanium alloy and stainless steel. Modal analysis and optimization techniques refine the structural parameters and improve the complex load performance. The research promotes the lightweight of the frame and provides theoretical and technical support for the design of multi-terrain vehicles.
Xu, Han, Xu, Shilin, Ma, Wenbo, Zhu, Wei
Calculation and Analysis of the Weight Increase of the Ship Chamber of the Three Gorges Ship Lift2025-99-030212/17/2025
Since the trial operation of the Three Gorges ship lift, in order to improve its functions, some equipment and structures have been modified, mainly including the modification of the filling and emptying system for docking, the modification of the bollard, and the modification of the operation platform and so on. This has led to an increase in the weight of the ship chamber, which may have adverse effects on the structure of the ship chamber, steel wire ropes, drive system motors, and safety mechanisms. Based on the compilation and analysis of relevant data including technical documentation modifications, on-site investigations, and drive system tests, this study determines the actual loads and boundary conditions of key components such as the ship chamber structure and wire ropes at the current stage. Combined with finite element analysis methods, it calculates the strength and stiffness of the existing ship chamber structure, verifies the safety factors of the wire ropes and the strength of safety mechanisms, and determines the margin in the drive capability of the motors. Through comprehensive analysis, a counterweight balancing scheme is proposed, along with follow-up active maintenance recommendations based on advanced materials, data-driven approaches, and digital twins. These findings serve as references for subsequent retrofitting work of the ship lift.
Cheng, Hang, Lu, Mingming, Wang, Di, Yang, Hua, Wu, Fan, Fan, Zhuo, Qin, Feng
Qualified Hoses for Marine ApplicationsJ1942/1_202512 (Current)12/17/2025
The following list consists of hose data provided as of December 2025 and is for convenience in determining acceptability of nonmetallic flexible hose assemblies intended for usage under 46 CFR Part 56.60-25. Where the maximum allowable working pressure (MAWP) or type of fitting is not specified, use the manufacturer’s recommended MAWP or type of fitting. This list has been compiled by SAE staff from information provided by the manufacturers whose product listings appear in this document. Manufacturers wishing to list their products in this document shall: a Successfully test their hose to the requirements of SAE J1942, Table 1. b Submit a letter of certification to the SAE J1942 test requirements for each specific type of hose tested (see sample table, Table 1) along with the test results. All sizes should be included in the same letter, which must also include all of the information necessary to make an SAE J1942-1 listing. c SAE will review the letter and may, at their discretion, request to see further test results. A copy of the submittal letter marked “Accepted for Listing” will be returned to the applicant upon approval. d The cutoff date for inclusion of a hose listing in the annual SAE Handbook is September 30 of the preceding year. However, listed hoses may be used on vessels as soon as the “Accepted for Listing” letter is issued by SAE.
Hydraulic Hose and Hose Fittings Committee
Design Innovations in Waterway Transport: Leveraging Horizontal Buoyancy2025-01-508012/15/2025
This paper attempts to introduce a unique water transport system by using open-bottomed air tanks in a water transport vehicle and using horizontal buoyancy instead of vertical buoyancy. This study explains how a certain amount of horizontal buoyancy is generated by attaching open-bottomed air vessels to commonly used small watercraft. In contrast to the fact that vehicles generally require a lot of water for all water transport, this new mode of transport can use a minimal amount of water, as appropriate for the weight, through a sufficient literature survey. The proposed water–air–based vehicle integrates open-bottomed air vessels with a hydrofoil system to generate horizontal propulsion. A model analysis is conducted to explain how the horizontal buoyancy force generated by the air vessels is related to the vertical buoyancy force, and their values at different depths are tabulated. The vehicle model can achieve a maximum speed of 1.5 m/s, handling 20–70 kg payload, highlighting potential for sustainable water-based transport. At high pressure, a final volume of 0.03 m3 produced 1 m/s in simulations versus 1.09 m/s experimentally at 0.03 m3, while final volumes (0.02–0.01 m3) showed close agreement, confirming model reliability. The simulation achieved a maximum velocity of 4 m/s at the highest compression level with final volume of 0.01 m3. Due to the inability to use high-pressure equipment, achieving higher compression levels (i.e., volumes as low as 0.01 m3) was not possible; therefore, experimental tests were only conducted at a final volume of 0.03 m3. These discoveries can be considered important in water transport, where the horizontal buoyancy force created by air vessel plays a key role, and this will pave the way for a great improvement in future water transport methods. This system leverages hydrostatic pressure differences as a renewable energy source, demonstrating that controlled air–water interactions can efficiently propel and stabilize a hydrofoil vehicle.
Santhiyagu, Arulanantha Samy
Investigation of Roll Motion Behavior in a Multi-Functional High-Speed Trimaran Unmanned Vessel2025-99-043912/10/2025
This study focuses on the multifunctional three-body high-speed unmanned boat model, and experimentally measures the roll attenuation characteristics under different draft conditions. It focuses on the influence of the initial roll angle on roll attenuation, and analyzes the change pattern of roll angle over time. Experimental results show that the model shows obvious self-oscillation period and amplitude attenuation. Based on the system identification theory and combined with improved genetic algorithms, a mathematical model used to simulate the roll attenuation motion of the boat model was constructed. The difference between experimental data and fitted values was further evaluated using identification software and verified with data at specific roll angles. In addition, the study also deeply analyzed the change trend of the roll moment coefficient with the initial roll angle. By comparing the experimental results of the three-mall boat and the catamaran, it was found that the three-mall boats were better than the catamaran in terms of roll resistance. These research results not only provide an important basis for the research on wave resistance of multi-body boat models, but also promote the technological progress of multi-body boats in wave resistance.
Zhang, Di, Tong, Wei, Yu, Qingzhu, Liu, Bofei
Training Uncrewed Underwater Vehicles for Visualization of Subsurface StructuresTBMG-5429012/1/2025
Establishing the Method for Simulation of Electric Potential in Cooling Water Passages of Outboard Motors2025-32-000811/3/2025
Producing 3D models of cooling water passages of outboard motors, and calculating distribution of electric potential on the water passage surfaces using BEM, we have developed the new method for simulation of electric potential distribution. The outboard motor is a propulsion system attached to the transom of the boat with steering function. As the water around the boat is drawn in for cooling of the engine, the engine parts are susceptible to severe corrosion. As a means to help prevent corrosion, a part referred to as the anode metal, which has a lower natural potential, is provided. Such a method is called the sacrifice protection because the anode metal corrodes before the engine parts due to the difference of electric potential. Since anti-corrosion currents occur preferentially to areas close to the anode metal, the anode metal is required to be located at the most effective place for corrosion protection. However, there are certain restrictions in the layout of anode metal from the engine configuration and parts layout. In addition to it, the identification of potential distribution requires measurements from the actual outboard motor. That was why it was challenging to realize a design having an ideal potential distribution. To deal with the issue, we conducted simulation of secondary current distribution in order to help predict potential distribution at the design stage. Taking actual measurements of polarization curves of outboard motor parts in the environment that matched the actual water passages and where the flow velocity existed, the measured data was uploaded as the simulation parameter. The calculated data of the potential distribution simulation are very close to the actual measurement. With the potential distribution simulation method established, it is now possible to lay out necessary number of anode metals at appropriate locations for corrosion prevention.
Shibuya, Ryota, Suzuki, Hiroki
Dome Profile Optimization and Stress Analysis of Type IV Composite Cylinders Using a CLT-Based MATLAB Program and FEA Validation2025-28-037410/30/2025
Type IV composite pressure (CP) vessels composed of a plastic liner and composite layers require special design attention to the dome region. The cylindrical portion of the composite cylinder is wrapped with composite layers consisting of the 900 hoop layers and low-angle helical layers, whereas the dome surface carries helical layers only. The winding angle of the helical layers being a constant over the cylindrical portion starts to vary from the cylinder-dome junction toward the boss at the top continuously. Along with the winding angle, the composite thickness also varies continuously resulting in a maximum thickness at the top crown region. The complete analysis and layer-wise stress prediction of Type IV composite cylinders for service pressures up to 70 MPa was analyzed by the Classical Lamination theory (CLT)-based MATLAB program. The MATLAB program developed in this work for the dome initially performs the dome profile generation through the numerical integration of the dome profile differential equations involving meridional and circumferential radii. A CLT formulation is successfully adopted in this work for predicting the stresses and strains accounting for the winding angle and composite thickness variations along the dome profile. A novel approach is implemented in ANSYS for accommodating the varying winding angle and composite thickness over the dome by invoking a lookup table feature in the ANSYS ACP Workbench module. The varying winding angles and composite thickness determined through the CLT MATLAB program are linked to ANSYS through the lookup table. This ensures a seamless data transfer and improves solution accuracy.
R. S., Nakandhrakumar, Tandi, Ronak, M, Ramakrishnan, Raja, Selvakumar, Elumalai, Sangeethkumar, Velmurugan, Ramanathan
Heat Flux Temporal Variation and Turbulent Structures on Diesel Flame-Impinged Wall by Comparing High-Speed Infrared Thermography and MEMS Sensor Measurements2025-24-00399/7/2025
For further elucidation of the extremely complex mechanism of wall heat transfer during diesel flame impingement, heat flux measurement results based on two different relatively new approaches, high-speed infrared thermography and Micro Electro- Mechanical Systems (MEMS) heat flux sensor, were compared. Both measurements were conducted on the chamber wall impinged by a diesel flame achieved in constant volume combustion vessels under similar experimental conditions. Infrared thermography was conducted using a high-speed infrared camera (TELOPS M3k, 13,000 fps, 128×128 pixels), allowing the capture of time-series temperature and heat flux distributions on the wall surface with a spatial resolution of 70 μm (9 mm / 128 pixels). This high-resolution imaging also enables detailed estimation of near-wall turbulent structures, which are considered to significantly influence the heat flux distributions. The MEMS sensor is composed of closely aligned (520 microns separated) multiple highly sensitive thin-film Resistance Temperature Detectors (RTDs) of 235×235 microns, enabling estimation of near-wall turbulent fluid motion based on a cross-correlation analysis of measured heat flux fluctuations. The comparison between these measurements allows for mutual complementation of limited temporal resolution and quantitative accuracy of high-speed thermography and limited ability for spatial comprehension of the near-wall turbulence structure using the MEMS sensor. The time-series heat flux distribution obtained via high-speed thermography exhibited distinctive radial striped patterns. These patterns initially appeared as fine streaks with a high advection velocity immediately after wall impingement. As time progressed, they gradually increased in scale and exhibited a decrease in advection velocity. This behavior likely reflects the development of a boundary layer on the wall surface during the highly transient diesel flame impingement. Similarly, the heat flux measured by the MEMS sensor showed a comparable trend: the measured oscillation frequency corresponded well with the behavior of the striped patterns observed in the thermography, and the estimated fluid motion velocity was high immediately after wall impingement but gradually decreased over time.
Shimizu, Fumika, Morooka, Masato, Aizawa, Tetsuya, Dejima, Kazuhito, Nakabeppu, Osamu
Stationary Sound Level Measurement Procedure for Recreational MotorboatsJ2005_202508 (Current)8/20/2025
This SAE Recommended Practice establishes the procedure for determining if recreational motorboats have effective exhaust muffling means when operating in the stationary mode. It is intended as a guide toward standard practice and is subject to change to keep pace with experience and technical advances.
Marine Technical Steering Committee
Shoreline Sound Level Measurement Procedure for Recreational MotorboatsJ1970_202508 (Current)8/15/2025
This SAE Recommended Practice establishes the procedure for measuring the sound level of recreational motorboats in the vicinity of a shore bordering any recreational boating area during which time a boat is operating under conditions other than stationary mode operation. It is intended as a guide toward standard practice and is subject to change to keep pace with experience and technical advances.
Marine Technical Steering Committee
Exterior Sound Level Measurement Procedure for Recreational MotorboatsJ34_202506 (Current)6/30/2025
This SAE Recommended Practice establishes the procedure for measuring the maximum exterior sound level of recreational motorboats while being operated under a variety of operating conditions. It is intended as a guide toward standard practice and is subject to change to keep pace with experience and technical advances.
Marine Technical Steering Committee
Feature-Based Stereo Vision for Ship-Deck LandingF-0081-2025-02135/20/2025
In this paper, we develop a new feature-based algorithm using stereo cameras to estimate stochastic ship-deck motion at high sea states. Unlike our previous algorithms, this algorithm is able to estimate the motion of arbitrary ship structures without prior information on the ship's visual appearance or geometry. The algorithm requires an initial pose and suffers from drift over time, which was resolved by fusing it with our previous 2D feature-based vision algorithm. The combined vision algorithm is validated using a simulated ship featuring 3D ship structures and 2D flight deck markings representative of a DDG-51 ship. The results indicate that the algorithm can accurately estimate the pose of a simulated ship undergoing Sea-State 6 motion. The vision algorithm was further validated in a simple free-flight test.
Chopra, Inderjit
Research on In-Vehicle Clustered Multi-Channel Active Noise Control System2025-01-00165/5/2025
To address the issue of intermittent engine intervention during the charging and discharging processes of hybrid vehicles, which results in roaring noise within the cabin, this paper proposes a semi-coupled cluster control strategy that offers superior overall performance. This strategy is based on the traditional multi-channel Active Noise Control (ANC) system and integrates the advantages of both centralized and decentralized control approaches. The proposed clustered control strategy reduces computational load by approximately 50% compared to the centralized control strategy, while maintaining comparable noise attenuation performance. Moreover, it demonstrates significantly improved stability over the decentralized control strategy, with outstanding noise reduction results. Using the MATLAB simulation platform, the performance of the proposed in-vehicle clustered control strategy is compared with that of traditional control strategies. Additionally, road test experiments are conducted on a programmable electric vehicle under typical operating conditions to verify the strategy's effectiveness. The results indicate that the clustered control strategy is highly applicable to multi-channel ANC systems in vehicles, achieving average noise reductions of 6 dB(A), 19.7 dB(A), and 3.8 dB(A) for the 2nd, 4th, and 6th-order incremental programmer noise at the headrest positions of the four seats, respectively. These results demonstrate both effective noise reduction and stability. The findings hold significant scientific and engineering value and can be applied to noise control in manned environments, such as airplanes and submarines.
Deng, Huiping, Lu, Chihua, Chen, Wan, Liu, Zhien, Chen, Pian, Dou, Sirui, Sun, Menglei
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