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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Trajectory tracking and vibration reduction in marine stern shaft-bearing systems using Model Predictive Control</title>
      <link>https://trid.trb.org/View/2742186</link>
      <description><![CDATA[The reduction of transverse vibration is necessary for suppressing amplitude and improving efficiency in the marine propeller shaft of ships. The Model Predictive Control (MPC) is proposed for marine stern shaft-bearing systems, utilising a combination of electromagnetic actuator and shock absorber. The acceleration of the sprung shaft and unsprung bearing, displacement of suspension travel and soleplate deflection, as well as the generated force of the actuator are calculated. Furthermore, the feedback MPC with state observer is compared to the estimated state values and the stability convergence under different initial state conditions are discussed. The effect of prediction horizons and adaptive prediction time domain on controlled behavior is investigated. Moreover, robustness analysis is conducted to discuss the reduction rate, overshoot rate and setting time with various control weighting matrices. Therefore, it can be concluded that more applicable transverse vibration reduction can be achieved with the MPC trajectory tracking strategies.]]></description>
      <pubDate>Tue, 01 Sep 2026 14:02:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2742186</guid>
    </item>
    <item>
      <title>CFD Analysis of a Stern Flap Effect on the Hydrodynamics of a Catamaran Ship</title>
      <link>https://trid.trb.org/View/2727480</link>
      <description><![CDATA[Maritime transport is under increasing pressure to improve hydrodynamic efficiency and decrease emissions. catamarans offer operational benefits; however, they are limited by wave-making resistance at high speeds. Stern flaps are effective for monohulls, but their optimization for catamarans is inadequately investigated owing to the complexities of twin-hull hydrodynamics. this work utilizes computational fluid dynamics simulations to comprehensively assess stern flap performance on a catamaran under varying ship speed conditions and angles of attack. the findings indicate that a 0° flap decreases overall resistance by an average of 5.5%, despite a 1.76% increase in wetted surface area, accomplished by separation-free flow and balanced trim correction, which includes a 42% reduction in stern-squat at higher froude numbers. conversely, a 20° flap elevates resistance by up to 8.8% at high froude numbers due to flow separation, which exacerbates a 4.48% increase in wetted area and a 0.49% rise in heave, despite its 93% geometric trim correction. research results indicate that neutral flap angles improve catamaran efficiency by avoiding three hydrodynamic drawbacks of higher angles: increased pressure drag, expanded wetted surface, and reduced stability. High-angle configurations are not recommended for any operating profiles.]]></description>
      <pubDate>Mon, 27 Jul 2026 09:46:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/2727480</guid>
    </item>
    <item>
      <title>Stern pressure identification using CNN-BiLSTM model based on bayesian optimisation and attention mechanism</title>
      <link>https://trid.trb.org/View/2690049</link>
      <description><![CDATA[Accurate identification of the stern pressure field holds significant engineering implications for controlling hull structure vibrations and propeller excitation effects. In order to address the accuracy defects of the traditional distributed load inversion method when applied to complex surface structures, a baseline neural network model has been introduced and improved. Furthermore, a method of intelligent identification of stern pressure based on the Bayesian optimization algorithm and the attention mechanism of the CNN- BiLSTM model has been proposed. Taking the KCS container ship as the research object, we constructed a multi-physical-field coupled dataset containing 65 stern pressure measurement points and 9 structural strain measurement points through CFD simulations under five propeller rotational speed conditions. CNN and BiLSTM are used to extract spatio-temporal features from the dataset. Dynamic feature weight allocation is achieved through an attention mechanism, while Bayesian optimisation determines hyperparameter values to reduce bias. Results demonstrate that compared with basic models (CNN-BiLSTM, GRU, etc.), BOA-CNN-BiLSTM achieves optimal performance across MAE, MSE, RMSE, and MAPE metrics, with R2 reaching 0.987. This method achieves high-precision and high-reliability reconstruction of multi-point pressure data at the stern through finite strain monitoring, providing an effective solution for distributed load identification in complex curved structures.]]></description>
      <pubDate>Wed, 24 Jun 2026 11:31:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2690049</guid>
    </item>
    <item>
      <title>Slam-induced loads on a three-dimensional stern model entering into water considering the bottom propeller shaft</title>
      <link>https://trid.trb.org/View/2607030</link>
      <description><![CDATA[The slamming load characteristics of stern structures under severe sea conditions are a research topic that deserves special attention. However, owing to the complex geometric characteristics of the stern, the current understanding of its slamming load characteristics is still insufficient. This study uses the computational fluid dynamics (CFD) method to conduct a numerical simulation study on the water impact problem of the stern structure of a container ship. Unlike previous studies, this calculation specifically considers the influence of the actual propeller shaft on the slamming process. The numerical calculation results were first compared with the existing experimental data for impact load verification, with errors within 10 %. Through numerical simulation, the details of the three-dimensional (3D) free surface flow that was difficult to observe in the experiment were successfully reproduced, and the flow separation and air bubble entrapment phenomena induced by the bottom propeller shaft were captured for the first time. The pressure distribution and slamming force characteristics of the stern surface for falling heights ranging from 250 mm to 900 mm were systematically analyzed, and the impact load‒time history curves of typical measurement points were discussed in detail. The findings reveal that fluid disturbances caused by the bottom propeller shaft weaken the correlation between the impact pressure and initial deadrise angle. Finally, the influences of parameters such as the impact velocity, model scale, shaft size, and model dimensions on the load characteristics were explored. These conclusions can help to improve our understanding of the slamming load characteristics of stern structures.]]></description>
      <pubDate>Mon, 27 Apr 2026 15:01:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2607030</guid>
    </item>
    <item>
      <title>Calculation of Free and Forced Lateral Vibrations of a Shaft Line Using Solution Coefficient Vectors</title>
      <link>https://trid.trb.org/View/2624164</link>
      <description><![CDATA[In this paper, the free and forced lateral vibrations of a marine propulsion shafting system on anisotropic supports are computed using the vectors of solution coefficients method. The transverse vibrations are considered in two orthogonal planes. The effect of the oil film in the bearings is taken into account. The stern tube bearing is considered as an elastic support of Winkler’s type. The whirling mode shapes for free vibrations of the system were calculated using the algebraic complements according to I.P. Natanson. The results show a decrease in vertical static deformation due to the distributed weight of the shaft line during the operation of the propelling system. This straightening of the propeller shaft explains the increase in the thickness of the oil film in the stern bearing, as observed by naval engineers.]]></description>
      <pubDate>Tue, 10 Mar 2026 09:57:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2624164</guid>
    </item>
    <item>
      <title>Structural health monitoring of water-lubricated stern bearing systems based on digital twins</title>
      <link>https://trid.trb.org/View/2637899</link>
      <description><![CDATA[To address the need for visualization monitoring and health assessment of water-lubricated stern bearing structures, a digital twin-based online monitoring method for the structural performance of water-lubricated stern bearing systems has been proposed. First, based on a five-dimensional digital twin model, a virtual model and virtual scenario of the water-lubricated stern bearing system were constructed, enabling interaction between the physical and digital spaces. Second, a surrogate model of the water-lubricated stern bearing system is constructed based on finite element simulation data, and a structural performance prediction model under time-varying and multi-dimensional operating conditions is established. Finally, a digital twin structural health monitoring system for water-lubricated stern bearings is established by integrating the virtual space, data transmission, and application modules on the Unity3D platform. The results indicate that the digital twin can achieve real-time data synchronization between the physical entity and the virtual model, providing a reliable data foundation for performance prediction; the surrogate model can dynamically predict structural performance and present it in real time in the form of a cloud map, significantly enhancing the real-time and intelligent levels of system health monitoring, and providing new insights for ship shaft system health management.]]></description>
      <pubDate>Tue, 10 Mar 2026 09:55:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/2637899</guid>
    </item>
    <item>
      <title>Numerical simulation of outdoor transient thermal-field effects on the press-fit curve of a ship stern-tube bearing</title>
      <link>https://trid.trb.org/View/2637864</link>
      <description><![CDATA[The press-fit process for the stern tube bearing is both critical and irreversible in shipbuilding. Any failure during this process can lead to substantial economic losses. However, current models predominantly rely on steady-state temperature assumptions, rendering them inadequate for predicting performance under real-world transient outdoor conditions. This study addresses this critical gap by integrating field experiments with numerical simulation to develop a high-fidelity finite-element model that captures the transient Thermal-Structural Coupling during open-air press-fit. We specifically elucidate how transient thermal fields affect geometric tolerances and the press-fit force-displacement curve. Under steady-state conditions, the stern tube's roundness deviation worsens with axial depth, yet the effective interference remains relatively stable. In contrast, transient fields induce more uniform but larger deformation in the bearing compared to the tube, significantly altering the interference fit: increasing temperature amplifies interference, while decreasing temperature diminishes it. This present work quantitatively delineates the impact of structural temperature gradients on the press-fit process, and the validated model reliably predicts press-fit curves across varying thermal environments. These findings establish a foundation for defining rational press-fit windows, optimizing process parameters, and ultimately mitigating press-fit risks to enhance the first-pass success rate.]]></description>
      <pubDate>Tue, 10 Mar 2026 09:55:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/2637864</guid>
    </item>
    <item>
      <title>Research on active control of vibration sound radiation of typical stern hull structures</title>
      <link>https://trid.trb.org/View/2631530</link>
      <description><![CDATA[Electromagnetic harmonic excitation from shipboard motors readily induces low-frequency vibration and noise in the stern hull structure of ships, compromising its acoustic stealth performance. This study proposes an active control method utilizing piezoelectric stack actuators. The methodology encompasses: firstly, analyzing and validating the electromechanical coupling mechanism of the piezoelectric stack actuator. secondly, determining the inherent characteristics of the stern hull through in-air and underwater modal analyses. Furthermore, simulate the acoustic radiation behavior of the stern hull under the excitation of different sound sources. For typical motor rotational conditions, quantify the vibration spectrum of the stern hull and the power flow transmission characteristics from the motor base to the stern hull. Under the premise of ensuring that the fixture does not affect the dynamic characteristics of the original structure, simulate the open-loop vibration control effect of installing the piezoelectric stack actuator. Ultimately, constructing an experimental system to measure force ranges of exciters and piezoelectric stack actuators, and validating both open-loop and closed-loop vibration control schemes under representative conditions. Collectively, this integrated approach suppresses stern hull vibrations within critical low-frequency bands, establishing a robust framework for enhancing marine acoustic stealth.]]></description>
      <pubDate>Wed, 18 Feb 2026 13:22:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/2631530</guid>
    </item>
    <item>
      <title>Influence of parameters on dynamic characteristics of friction-induced self-excited vibration in the ship stern shaft seal</title>
      <link>https://trid.trb.org/View/2585388</link>
      <description><![CDATA[The stern shaft seal is crucial for maintaining the operational reliability and environmental integrity of ship propulsion systems. Friction-induced vibrations significantly affect the service life of these seals. This study develops a nonlinear dynamic model of the stern shaft seal, considering frictional contact, and investigates the dynamic characteristics of the seal, as well as the influence of key structural and operational parameters on friction-induced self-excited vibrations. The result shows that friction-induced torque in stern shaft seals triggers negative damping, leading to self-excited vibrations, and critical structural parameter thresholds within specific speed ranges are established. This study provides valuable reference for the optimal design of stern shaft seals in ships.]]></description>
      <pubDate>Fri, 08 Aug 2025 08:51:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2585388</guid>
    </item>
    <item>
      <title>The unwetted height of transom-stern monohull ships and the Neumann–Michell ship flow computations</title>
      <link>https://trid.trb.org/View/2585181</link>
      <description><![CDATA[The unwetted height Edry, characterized by free-surface depression directly aft of the transom stern, is apparently affected by the intricate bubble flow observed within the transom-draft Froude numbers 1.3<FT<1.7. To exclude measurement uncertainties caused by these multiphase flow interactions, the data corresponding to Edry within this Froude range is omitted from subsequent analysis. Subsequently, a refined regression model for unwetted height prediction is developed to address this limitation. The proposed formulation improves the accuracy of total resistance predictions based on the Neumann–Michell potential flow theory, especially at low Froude numbers (FT<1.3). Additionally, a novel methodology is proposed to analyze the wave pattern, explicitly accounting for the nonlinear effects of the free-surface hollow. This approach reveals that stern ship waves are predominantly governed by free-surface potential in the present case, which is directly influenced by the geometry of the hollow.]]></description>
      <pubDate>Fri, 08 Aug 2025 08:51:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/2585181</guid>
    </item>
    <item>
      <title>Astern Running of Heavy-Tonnage Vessels in an Ice Channel</title>
      <link>https://trid.trb.org/View/2488157</link>
      <description><![CDATA[One of the most important tasks in raising the efficiency of marine transport systems is to make heavy-tonnage vessels move at faster speeds in channels laid by icebreakers. Studies conducted in the Krylov State Research Center (KSRC) Ice Basin have shown that broken ice is a significant factor that restricts vessel speed through ice channels. Wide breadths of heavy-tonnage vessels make it difficult to push ice pieces aside, resulting in their accumulation ahead of the bow. Ice blocks can be removed from the bow area only if they are immersed and passed along the hull underwater. With increasing speed, these processes require increasing amounts of energy. Possibly, easy ice passage along the underwater hull and speed improvements can be achieved if large-size vessels go stern first in ice channels. In this mode of operation, the authors have a number of factors contributing to the more efficient passage of ice provided by the small angle of the sternpost, making it easier for ice floes to dive under the hull, as well as the suction produced by the propellers. Moreover, the propeller slipstreams wash away the submerged ice outside the channel edges and reduce the ice friction of the underwater hull. This paper provides some theoretical assessments regarding the efficiency of running a large-sized vessel astern in an ice channel. Model studies have been undertaken in the KSRC Ice Basin to confirm that the suggested mode of operation is effective. During these experiments, models of large vessels were run through an ice channel to determine their ice resistance and speed. The theoretical estimates were compared with the model test results obtained for the Ice Basin. The analysis of all results proves that the described mode of operation promises faster vessels through ice channels.]]></description>
      <pubDate>Fri, 18 Jul 2025 09:05:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/2488157</guid>
    </item>
    <item>
      <title>Multi-objective optimization of a fishery administration vessel's stern flap design based on surrogate model</title>
      <link>https://trid.trb.org/View/2568128</link>
      <description><![CDATA[The speed and motion attitude of a fishery administration vessel affect the efficiency of completing tasks. The stern flap, as a common drag reduction device, plays a key role in determining hydrodynamic performance based on its parameter values. A parameter-based modeling method is proposed, which allows for continuous changes in the shape and installation position of the stern flap. Using Sobol sampling to obtain sufficient samples, the sensitivity of the parameters is analyzed. The installation height has the greatest impact on drag and motion attitude, with a contribution rate ranging from 7.92 % to 12.35 %. A Kriging model trained with these samples is used to predict the drag value, trim angle, and sinkage value of the vessel under different parameter settings. The results show that, in the V-shaped stern flap configuration, the minimum drag of 64.139 N is achieved when the parameters are 10.607, 0.003, 0.102, and 0.328. For the vessel with a flat-plate stern flap, the best motion attitude is obtained when the parameters are 27.519, 0.006, 0.095, and 0.272. By selecting the appropriate type of stern flap and design parameters, both drag reduction and optimization of motion attitude can be achieved, providing significant engineering and design reference value.]]></description>
      <pubDate>Fri, 18 Jul 2025 09:05:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2568128</guid>
    </item>
    <item>
      <title>Review of hydrodynamics, design and optimisation of stern flap on high-speed displacement ships</title>
      <link>https://trid.trb.org/View/2533948</link>
      <description><![CDATA[The shipping industry faces rising fuel costs, stricter environmental regulations, and increased competition, driving the demand for innovative solutions to reduce operating expenses and environmental impact. Stern flaps, appendages installed at a ship's stern, have emerged as a promising solution for enhancing vessel hydrodynamics, reducing resistance, and improving propulsive efficiency, leading to significant fuel savings. This review paper analyses the literature on stern flaps' hydrodynamic performance, design, and optimisation for high-speed displacement ships to identify areas needing further research and development. This review advances sustainable and efficient shipping practices by investigating stern flap hydrodynamics and exploring optimisation techniques. It provides valuable insights for researchers, industry professionals, and policymakers, supporting efforts towards environmentally friendly and cost-effective shipping operations.]]></description>
      <pubDate>Thu, 08 May 2025 09:56:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2533948</guid>
    </item>
    <item>
      <title>Numerical parametric assessment of the effects of stern wedges on the pressure and friction resistance of high-speed craft</title>
      <link>https://trid.trb.org/View/2434011</link>
      <description><![CDATA[In the current study, wedge effects on a planing hull's friction and pressure resistance components have been numerically investigated. This study also assesses how the variation of pressure and friction resistance components can be predicted by trim angle variation. The obtained results indicate that at Frb < 0.9, stern wedges slightly increase the vessel's pressure resistance. By increasing the speed, pressure, and friction resistance components of the wedge-mounted model descends and increases, respectively, compared to the baseline model. The results indicate that the wedge-mounted planing hull experience a decrease in pressure resistance of up to 27% and an increase in friction resistance of up to 34%. After Frb = 2.15, some interaction effects between the wedge length and height on the total and pressure resistance appear. The findings also indicate that wedge effects on the planing hulls' pressure and friction resistance components are much different from those of displacement hulls.]]></description>
      <pubDate>Thu, 31 Oct 2024 16:20:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/2434011</guid>
    </item>
    <item>
      <title>Combined Effects of Axial Flow and High System Rotation on the Fluid Dynamics of Taylor-Couette-Poiseuille Flow</title>
      <link>https://trid.trb.org/View/2437384</link>
      <description><![CDATA[Taylor-Couette-Poiseuille (TCP) flow, characterized by the flow through an inner rotating shaft and an outer stationary cylinder, is a fundamental flow system in many industrial applications, including ship stern tubes, turbomachinery, journal bearings, and offshore drilling. Understanding the hydrodynamics of the TCP flow offers significant benefits for ensuring the robust design and operational efficiency of such systems. This paper presents the numerical modeling of turbulent TCP flow to assess the combined effects of two key control parameters-axial Reynolds number (10000-30000) and Taylor number (2.2x10⁷-3.1x10⁹)-on the fluid dynamics within the system. Using Reynolds Stress Modeling, this study investigates the behavior of TCP flow at high Reynolds numbers, which is relevant to real-world rotating machinery. The results indicate that the interaction between rotation and axial flow is not linear, with high rotation rates showing distinct behavior from low rotation rates, especially in the throughflow effects. At low and moderate rotation numbers (N), both the mean and turbulent variables display strong dependence on the rotational velocity and axial flow rate. However, further increases in N lead the flow field to be increasingly dominated by the contribution of rotation, and mean flow variables become relatively independent of the imposed flow rate. Furthermore, systematic deviations from the log-law in the boundary layer velocity profiles further emphasize the need to account for the combined effects of rotation and axial flow in the TCP flow system design and operation.]]></description>
      <pubDate>Wed, 30 Oct 2024 11:07:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2437384</guid>
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