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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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    <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>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>OPTIWISE Sailing into the Future: Wind Assisted Propulsion of Ships</title>
      <link>https://trid.trb.org/View/2581611</link>
      <description><![CDATA[This paper presents findings of the Horizon Europe project OPTIWISE, which focuses on developing innovative design methods for ships equipped with wind-assisted propulsion. The project encompasses comprehensive evaluations, including environmental, economic, and business impacts. Three distinct design cases are explored: a bulk carrier using Rotor Sails, a tanker fitted with Oceanwings, and a passenger vessel with Solid Sails. The wind-assisted propulsion systems are detailed, along with the design and evaluation methodologies employed. Rotor Sails harness the renewable power of wind through the Magnus effect, significantly reducing fuel consumption and emissions. Oceanwings provide additional thrust to vessels. Solid Sails, a modern take on traditional sails, are constructed using advanced materials and have versatile applications. OPTIWISE also introduces innovative design and evaluation methods that consider the holistic impact of wind propulsion on ship design. The need for a more integrated approach is emphasized, where all relevant subsystems are evaluated and optimized together, considering the full operational conditions. As the shipping industry journeys towards sustainability, wind-assisted propulsion systems offer a promising solution. OPTIWISE's insights and methodologies contribute to the adoption of these innovative technologies, fostering a greener and more efficient future for maritime transport.]]></description>
      <pubDate>Thu, 18 Jun 2026 08:54:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2581611</guid>
    </item>
    <item>
      <title>High-Precision Nonlinear Semi-Analytical Model of High Torque Density 3-D Magnetic Circuit Permanent Magnet Motor in Aircraft Electric Propulsion Application</title>
      <link>https://trid.trb.org/View/2665607</link>
      <description><![CDATA[This article proposes a novel high-precision nonlinear semi-analytical model for the magnetic fields and the electromagnetic performance calculation of 3-D magnetic circuit permanent magnet motor (3DMCPMM) in aircraft electric propulsion applications, which can take the effects of the magnetic saturation nonlinearity and the permanent magnet (PM) end-leakage flux into account. The high torque density 3DMCPMM topology is first proposed, which can improve the output torque per unit weight via the 3-D magnetic circuit coupling. To simplify the computation, the 3-D magnetic circuit equivalent decoupling method is proposed for 3DMCPMM, which can convert the 3-D magnetic circuit into dual 2-D magnetic circuits. The 3DMCPMM analytic model is then proposed based on the harmonic subdomain approach, which can accurately predict the magnetic field distribution and the electromagnetic performance. Furthermore, using the equivalent magnetic circuit (EMC) model, the PM end leakage flux coefficient is proposed for the 3DMCPMM analytic model, which can eliminate the calculation error due to the PM end-leakage flux effect. The nonlinear iteration-based magnetic permeability is proposed for the 3DMCPMM analytic model, which can improve the analytic calculation accuracy by considering the magnetic saturation nonlinearity. A 630-N ⋅ m 3DMCPMM is designed and manufactured with the torque density of 25.37 N ⋅ m/kg. Simulation and experimental results show that the proposed semi-analytic model has an excellent electromagnetic prediction performance with a maximum calculation error of 4.62%, which can achieve the analytic calculation of 3-D magnetic circuit motor. The 3DMCPMM semi-analytical model is proposed for the first time, which lays the foundation for the 3DMCPMM rapid design and iterative optimization.]]></description>
      <pubDate>Wed, 17 Jun 2026 16:13:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665607</guid>
    </item>
    <item>
      <title>Development and Optimization Method of Machine Considering Matching Integrated Rim-Driven Fan for Aviation Electric Propulsion</title>
      <link>https://trid.trb.org/View/2665595</link>
      <description><![CDATA[The rim-driven fan (RDF) is a distinctive aviation electric propulsion system where fan blade tips are directly driven by a rim-driven induction motor (RDIM). This configuration offers higher propulsion efficiency and a stronger correlation between fan torque demands and motor output torque. Within this study, a model of the nonlinear load characteristics of the RDF is established, and principles governing the matching of RDIM output performance across diverse flight conditions are derived. A method for determining the rational design boundaries of the RDIM is formulated, which can guide the matching design between the RDIM and different RDFs. These design constraints for the RDIM encompass torque-fan load matching, output power, and power factor requirements. Although the preliminary design satisfies basic operational requirements, significant opportunities exist to enhance system efficiency and power density. A stepwise optimization method for aviation multioperating conditions is proposed, which gradually optimizes independent objectives required for different operating conditions, ultimately targets three balanced core objectives for the Pareto frontier, enables RDIM to achieve system optimization under diverse operating conditions, and enhances RDF propulsion efficiency. A prototype is developed and tested to experimentally validate the efficacy of the proposed design approach.]]></description>
      <pubDate>Wed, 17 Jun 2026 16:13:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665595</guid>
    </item>
    <item>
      <title>Reliability assessment for a Vehicle-to-Grid mode system with performance sharing</title>
      <link>https://trid.trb.org/View/2679616</link>
      <description><![CDATA[In this study, a novel performance sharing system based on the Vehicle-to-Grid (V2G) concept is introduced. In a V2G framework, electric vehicle batteries serve a dual purpose: providing propulsion and storing electrical energy. Accordingly, the proposed system incorporates multiple units capable of both absorbing and delivering performance. These units not only satisfy their individual performance requirements but also act as suppliers to support the overall system. To characterize system reliability, different distinct reliability levels, defined by the proportion of total demand that can be satisfied, are utilized as the primary reliability metrics. The reliability analysis is conducted by using Markov processes to compute the state probabilities of individual units and the universal generating function technique to evaluate the reliability of the entire multi-unit system. Additionally, a numerical example involving a V2G system is presented to demonstrate the effectiveness of the proposed model and methodology.]]></description>
      <pubDate>Wed, 17 Jun 2026 16:13:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2679616</guid>
    </item>
    <item>
      <title>Enabling Circularity in the Aerospace Maintenance Ecosystem through Generative-AI Driven Back-to-Birth Traceability of Life-Limited Engine Parts</title>
      <link>https://trid.trb.org/View/2712113</link>
      <description><![CDATA[Circular-economy principles are increasingly central to aerospace sustainability strategies, aiming to extend asset life, improve asset valuations, and enhance benefits to stakeholders in the part ownership and maintenance lifecycle. In aircraft engines, achieving circularity hinges on safe reuse, repair, and recirculation of high-value components. Life-Limited Parts (LLPs) are among the most critical in this context, but their reuse is strictly contingent on complete Back-to-Birth (BtB) traceability. Any gap in BtB records—often due to fragmented data across multiple airline operators, shop visits, document formats, and time expanse—renders otherwise serviceable LLPs unusable, leading to premature scrappage and lost circular value.This paper presents a Generative AI (GenAI)-driven methodology to reconstruct and validate complete LLP BtB histories from heterogeneous, unstructured, and legacy maintenance datasets. By combining aerospace domain-trained language models with embedded life accounting logic and regulatory compliance reasoning, the approach produces audit-ready documentation that assists the asset owners in meeting regulatory standards from aviation authorities such as EASA and FAA. Enhancing traceability to LLPs enables their safe re-entry into operational service, supports the module swaps market, and optimizes part pooling strategies. The result is a digital enabler for circularity in the engine lifecycle—preserving material value and maintaining uncompromised safety and compliance in aviation.]]></description>
      <pubDate>Wed, 10 Jun 2026 17:08:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/2712113</guid>
    </item>
    <item>
      <title>Design of Acoustical Features for a Quitter Aero-Engine Test Facility</title>
      <link>https://trid.trb.org/View/2712107</link>
      <description><![CDATA[It is a general practice to test aero engines to evaluate their performance in specially designed indoor test facilities after assembly, repaired or overhaul. Acoustic features are provided in the test facility to attenuate the noise level to a comfortable and acceptable level. Design of these features specially air intake and exhaust silencers are a challenging task in a flow field like aero-engine test facility considering the very high sound pressure level generated by them during test containing a very wide frequency band. Moreover, growing population and location of these facilities in the vicinity of residential areas has added this challenge in multifold. Also, the capital investment in building these facilities is huge due to their large size and longer construction time. Hence, the correct execution at first shot including design, fabrication and commissioning is very important. An attempt has been made to reduce design errors or improve the accuracy in the design stage by using commercially available acoustics analysis tools followed by laboratory measurement of sample features, which will reduce the lead time and cost of the project in design and implementation of the acoustic features for aero engine test facilities used for military application. This paper outlines the design of acoustics features such as air intake silencers, air cooled exhaust silencer, acoustic panels, sound proof doors and bullet resistant view window, which has produced significant improvement of noise level in and around the test facility.]]></description>
      <pubDate>Wed, 10 Jun 2026 17:08:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/2712107</guid>
    </item>
    <item>
      <title>Numerical investigation of the parafoil-assisted ship system in a wind environment using the fluid-structure interaction method</title>
      <link>https://trid.trb.org/View/2710027</link>
      <description><![CDATA[Parafoil-assisted ship systems are capable of harnessing high-altitude strong wind energy to provide propulsion. the nonlinear fluid-structure interaction numerical method is proposed for marine parafoil systems operating in wind field environments. Additionally, the ground-based wind field loading method is conducted through boundary conditions, where the wind is applied to the parafoil system as an independent variable. The incorporation of a fluid time-step updating technique effectively reduces the computational domain size of the fluid field. Overall, the Arbitrary Lagrange-Euler method is employed to investigate fluid-structure interaction for both ship structures coupling with water and air domains, and for parafoils coupling with air domains. The presented method is validated through data from towing tank tests and wind tunnel experiments.Results show the parafoil maintains stable downwind flight attitude. Increasing wind direction angle significantly raises the parafoil's deflection and roll angles, with minimal pitch change. Crosswinds induce asymmetric airfoil fluid separation, reducing thrust and increasing lateral force, with limited impact on ship yaw and small additional resistance. Stress concentration easily occurs at the middle of the parafoil's leading and trailing edges under crosswinds, while airfoil deformation is barely affected by wind direction angle. The parafoil provides 8%–15% thrust under typical conditions, offering theoretical support for its engineering application and structural design.]]></description>
      <pubDate>Wed, 10 Jun 2026 16:38:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2710027</guid>
    </item>
    <item>
      <title>Physical Modelling of Container Ship Propulsion and Comparison with Operational Data</title>
      <link>https://trid.trb.org/View/2581581</link>
      <description><![CDATA[International Maritime Organization (IMO) has adopted a strategy to reduce at least 50% of GHG emissions from the global shipping sector by 2050, compared to 2008. Preparing for these requirements, a 4-year R&D project, TNTM (Digital Transformation of Maritime Transport) was initiated. As part of this project, the current work presents the physical models that compares their outputs with actual on-board measurements on a LNG powered containership. The main propulsive systems were modelled using SEECAT (Ship Energy Efficiency Calculation and Analysis Tool), an in-house tool developed by Bureau Veritas Marine & Offshore. A custom hull performance model was developed assuming the vessel’s static equilibrium under the different forces and moments. The later have been estimated through CFD and includes calm water resistance depending on drift & rudder angles as well as added resistance by wave and wind. A simulation has been performed for a complete rotation, which lasts about 3 months between Asia and Europe. The comparison of the numerical results and the data recorded at sea were carried out. A good agreement has been obtained, the root-mean-square error during the steady state of the engine power and the fuel consumption is 7.6% and 9.1% respectively.]]></description>
      <pubDate>Fri, 05 Jun 2026 16:39:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2581581</guid>
    </item>
    <item>
      <title>Electromagnetic and Thermal Influence of Aspect Ratio on Flat-Type High Torque Density Dual-Rotor Permanent Magnet Motor for Aircraft Electric Propulsion</title>
      <link>https://trid.trb.org/View/2665538</link>
      <description><![CDATA[To achieve high torque density in direct-drive permanent magnet propulsion motors, flat-type motor topologies with large outer diameters and short stack lengths are generally preferred. However, such flat motor designs may also lead to performance degradation due to the negative impacts of end-winding weight, end-leakage magnetic flux, and temperature rise. This article investigates the influence of aspect ratio (stack length to outer diameter ratio) on both electromagnetic and thermal performances of high torque density dual-rotor permanent magnet synchronous machines (PMSMs) for aircraft electric propulsion. First, the design essentials of the compact high torque density dual-rotor PMSM are described. Then, the influences of aspect ratio on electromagnetic performances are analyzed considering end effects under different torque demands. The motors are optimized through a genetic algorithm based on 2-D and quasi-3-D models, respectively, to either neglect or account for end-leakage flux, elucidating the necessity of considering end effects during the optimization and analysis process. Furthermore, the influences of aspect ratio on loss and temperature distributions in heat pipe cooling systems attached to either active or end windings are comparatively analyzed, indicating that excessively flat topologies lead to higher temperature rise. Finally, by comprehensively considering effects on electromagnetic and thermal performances, an appropriate aspect ratio is selected. A 100-kW flat-type dual-rotor PMSM with end-winding heat pipes is developed and tested to confirm the analysis.]]></description>
      <pubDate>Thu, 04 Jun 2026 11:57:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665538</guid>
    </item>
    <item>
      <title>A multifidelity modelling workspace for the evaluation and design of wind assisted ships</title>
      <link>https://trid.trb.org/View/2706859</link>
      <description><![CDATA[Wind-assisted propulsion systems are becoming increasingly important due to the availability of strong winds in the oceans. These systems convert wind power directly into thrust, replacing fossil fuels with clean wind energy. Accurate performance predictions and an understanding of how ship dynamics and operation change are critical to utilizing such systems efficiently. Depending on the modelling approach and control system used, performance evaluations can vary significantly. This study systematically investigates various system architectures and subsystem definitions to understand the impact of modelling and control aspects on operation and fuel saving. Three system architecture levels were created, considering sail-only models, one-degree-of-freedom models, and three-degrees-of-freedom models, with a variety of subsystem models at different levels of fidelity, to understand their impact on performance predictions. The results obtained show that including the wind speed gradient affects the predicted fuel savings by up to approximately 75%. Similarly, models with speed and course controllers predict fuel savings 3–4 times greater than those with a heading controller and fixed propeller revolutions. To determine the contribution of sails to fuel savings, it is necessary to include sufficient information and how ship energy systems react to the implementation of sails in various environmental conditions through control systems.]]></description>
      <pubDate>Tue, 02 Jun 2026 13:56:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2706859</guid>
    </item>
    <item>
      <title>Experimental investigation of pulsed operation for marine propellers</title>
      <link>https://trid.trb.org/View/2706882</link>
      <description><![CDATA[Pulse jet propulsion has been tested experimentally in a towing tank for a model-scale, rim-driven ducted thruster and compared to steady operation. Enabled by high-acceleration thruster technology, the experiment was conducted with the goal of reproducing reported propulsive efficiency benefits from pulse jet propulsion by dynamically varying the rotational velocity of a conventional ship propeller. The tests included operation in bollard pull and with forward velocity. Propeller revolution, thrust, and torque, and the duct thrust were measured to provide reliable data of the useful and total power generated by the thruster. Formation of vortex rings has been qualitatively verified with pitot and optical measurements, but with a limited duration before the vortex rings dissipated in the propeller wake. Comparing the generated thrust with the same average rotational velocity, pulse jet propulsion generates thrust up to 2–3 times that of steady operation, consistent with the quadratic relationship between total thrust and the propeller’s rotational speed. The thruster did not replicate the reported benefits of efficiency in tests with forward velocity. In tests at zero speed, the thrust-power relation was the same or deficient of the steady propeller operation for all cases tested. Acceleration-dependent dynamic effects from acceleration and retardation of the propeller have been identified. A static model is presented and used for evaluating the dynamic contributions to performance. The static model predicts the obtained results, explaining the reduced efficiency of unsteady operation primarily as a result of the higher-order relation between power and propeller revolutions compared to the total thrust.]]></description>
      <pubDate>Mon, 01 Jun 2026 09:14:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/2706882</guid>
    </item>
    <item>
      <title>Integrated Levitation–Propulsion–Guidance Implementation and Operation Control for Active-Steering Maglev Car</title>
      <link>https://trid.trb.org/View/2665500</link>
      <description><![CDATA[To achieve integrated levitation–propulsion–guidance and precise longitudinal, lateral, and yaw motion control for the active-steering maglev car with permanent magnet electrodynamic wheels (PMEDWs), this article proposes a lateral guidance force compensation scheme and a multimode operation control method based on deflected PMEDWs. First, the triaxial electromagnetic forces are regulated through precise control of the PMEDW’s rotational speed and deflection angle, realizing the integrated levitation–propulsion–guidance functionality. Second, the vehicle’s longitudinal, lateral, and yaw operation modes based on the PMEDWs’ differential mode and deflection mode are proposed, followed by corresponding dynamics analyses. Finally, a dual-loop cascade controller is designed for vehicle motion control, and a prototype with its experimental platform is developed for validation. Experimental results demonstrate that the active-steering maglev car can effectively realize forward/backward motion, lateral translation, and in situ steering under multimodal operation control. Specifically, compared to the PMEDWs’ differential mode, the deflection mode significantly enhances longitudinal and yaw operating control performance: the average settling time and overshoot for longitudinal motion are reduced by 43.48% and 36.01%, respectively, while those for yaw motion are reduced by 37.42% and 26.04%, which verifies the effectiveness of the deflection mode and the controller.]]></description>
      <pubDate>Fri, 29 May 2026 14:09:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665500</guid>
    </item>
    <item>
      <title>Multimodal Underwater Transformable Agent for Efficient Marine Transportation in Dynamic Spatiotemporal Environments</title>
      <link>https://trid.trb.org/View/2658946</link>
      <description><![CDATA[Marine intelligent transportation systems (M-ITS) face challenges in achieving adaptability and efficiency under dynamic spatiotemporal (ST) environments. This paper proposes a novel multimodal underwater transformable agent (MUTA) designed as an adaptive and efficient information node for M-ITS. The MUTA integrates a biomimetic morphing wing, multi-drive propulsion system, incremental environmental perception, and an uncertainty-aware dynamic modeling framework to switch smoothly among long-range (LR) cruising, high-maneuverability (HM) operation, and synergy modes. Comprehensive lake and sea trials demonstrate that the MUTA maintains high motion precision and achieves significant energy efficiency improvements, reaching depths up to 1200 m and covering a range of over 3000 km. The MUTA has achieved over 17% efficiency gain in lake and marine environments. This work provides an adaptive and efficient solution for M-ITS under uncertain marine conditions.]]></description>
      <pubDate>Thu, 28 May 2026 17:09:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/2658946</guid>
    </item>
    <item>
      <title>Novel In-Slot Direct Cooling Structure of Concentrated Winding Permanent Magnet Electrical Machine for Aerospace Propulsion</title>
      <link>https://trid.trb.org/View/2665496</link>
      <description><![CDATA[With the development of high-power-density electrical machines, in-slot direct cooling has become a key method to overcome power density limitations. To further enhance the thermal performance of stator oil direct cooling, three novel cooling structures are proposed and systematically compared, with the optimal structure being identified. The structure introduces tooth- and wedge-side oil paths to increase the contact area between the winding and coolant, and further incorporates oil-blocking teeth at the slot bottom to adjust the flow rate and velocity distribution of different paths. First, three novel direct cooling structures and a conventional structure are introduced, and their coolant flow paths are analyzed. To simplify modeling, a thermal conductivity equivalent model for formed litz wires is developed and validated. In addition, electromagnetic and mechanical performance are evaluated. Finite element results show stable torque across all designs, while harmonic response analysis indicates that the added features enhance stiffness and reduce vibration near excitation frequencies. Computational fluid dynamic (CFD) simulations are then conducted to assess flow distribution, coolant velocity, and temperature under various conditions. Results show that the proposed structures effectively reduce winding temperature rise. A stator tooth-slot module is also tested, and the experimental results align well with simulations, validating the analysis and thermal model.]]></description>
      <pubDate>Thu, 28 May 2026 10:47:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665496</guid>
    </item>
    <item>
      <title>Phase-based station-keeping strategy for unmanned sailboats: Disturbance estimation and navigation mode switching</title>
      <link>https://trid.trb.org/View/2705064</link>
      <description><![CDATA[Unmanned sailboats, as a typical underactuated surface vehicle, convert wind energy into propulsion with sails. Without any propulsors, they are susceptible to the impact of wind field and cannot navigate arbitrarily, which makes station keeping particularly challenging, especially in marine environments with unknown disturbances. To address this problem, this study proposes a phase-based (PB) station-keeping strategy for unmanned sailboats, consisting of a disturbance estimation method, a navigation mode switching mechanism, and a heading controller. The estimation method estimates the disturbance-induced drift acting on the sailboat from the track error observed during straight navigation in the current phase. According to the estimation results, the navigation mode switching mechanism adaptively adjusts the navigation mode and generate the desired heading in the subsequent phase to achieve station keeping within a prescribed region. Based on the 2.5 m unmanned sailboat developed by the team, a simulation platform is established to evaluate the proposed PB strategy under varying intensities. Compared with existing strategies, the PB strategy achieves the best station-keeping performance, reducing the median lateral deviation while significantly decreasing the no-go zone proportion and increasing the dead circle proportion. In the sea trial, the unmanned sailboat operating under the PB strategy completed two station-keeping missions exceeding 30 min within a dead circle of 80 m radius, confirming the effectiveness and practical applicability of the proposed strategy.]]></description>
      <pubDate>Thu, 28 May 2026 09:05:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2705064</guid>
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