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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>Research on Fuel Cell Turboelectric Power Technology for Electric Aircraft</title>
      <link>https://trid.trb.org/View/2697084</link>
      <description><![CDATA[Electric aircraft will usher in a new era of low-altitude transportation and mark a third personalized transportation revolution. The power systems of electric aircraft must deliver ample power during takeoff and landing, operate at high efficiency during cruise, and exhibit high power density. Meeting all of these requirements is challenging for current power systems. We propose integrating fuel cells into the combustor of a conventional gas turbine to form a new fuel cell turboelectric power system for future electric aircraft. Its performance is compared with that of four other powertrains in a typical electric aircraft flight scenario through thermodynamic analysis. We demonstrate that the full Li-ion battery configuration remains suitable for short-range applications. In contrast, the fuel cell turboelectric power system is more efficient for medium- to high-range cruise requirements above 300 km. For a maximum cruising range of 500 km, the total equivalent hydrogen consumption of the fuel cell turboelectric power system is only 6.4 kg, approximately 50% of that of powertrains using conventional turbogenerators and batteries. Preliminary experiments are also conducted to validate the feasibility of developing a fuel cell turboelectric power system. The results demonstrate that a proton exchange membrane fuel cell can operate steadily with a flame combustor or a catalytic combustor. The outlet temperature of the fuel cell combustor can reach 1200 °C and is easily controlled by adjusting the gas flow rate to meet specific requirements. The power density of the manufactured finned tubular solid oxide fuel cell can also reach 1.2 W·g−1, thus meeting the requirements of future fuel cell turboelectric power systems. This study provides a technical and systematic foundation for the development of fuel cell turboelectric power systems.]]></description>
      <pubDate>Tue, 05 May 2026 09:26:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/2697084</guid>
    </item>
    <item>
      <title>Advancing Oil Consumption Prediction with 3-D Multiphase CFD: Insights into Piston Design Impacts</title>
      <link>https://trid.trb.org/View/2691999</link>
      <description><![CDATA[Engine oil consumption contributes to hydrocarbon and particulate emissions, catalyst degradation, and reduced thermal efficiency. Reducing it is essential for meeting emission standards and improving engine reliability. This study introduces a 3-D Computational Fluid Dynamics (CFD) framework that captures micron-scale gaps in the piston-ring-cylinder system while accounting for ring dynamics. The model leverages Simerics-MP+ features—including a novel mesh motion strategy and Mismatched Grid Interface (MGI) coupling—to resolve fine crevice regions alongside coarser bulk domains. It incorporates piston translation, ring motion, and crankshaft rotation, and uses the Volume of Fluid (VOF) method to capture multiphase interactions in thin oil films. Compared to experiments, this approach offers detailed flow visualization in optically inaccessible regions at lower cost and complexity. Unlike traditional 1-D models, it captures nonlinear behaviors without relying heavily on parameter tuning. Applied to a single-cylinder engine, the model evaluates oil transport in two piston designs under fixed RPM and undeformed bore conditions. Results highlight piston geometry’s role in oil consumption, and qualitative validation against experiments confirms the model’s predictive capabilities. This CFD framework provides valuable insights to guide low-emission, high-efficiency engine design.]]></description>
      <pubDate>Thu, 30 Apr 2026 16:39:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2691999</guid>
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    <item>
      <title>Predicting the Impact of FIA 2026 Power Unit Regulations on the Performance of Formula 1 Car</title>
      <link>https://trid.trb.org/View/2691995</link>
      <description><![CDATA[This work investigates the impact of the forthcoming 2026 FIA Formula 1 power unit regulations on vehicle track performance. This new regulation introduces a rebalanced power distribution between the internal combustion engine and the Motor Generator Unit-Kinetic (MGU-K), with each unit contributing up to 350 kW. This transition nearly triples the previous 120 kW output of the MGU-K while constraining the internal combustion engine through newly imposed fuel energy limits. A full vehicle powertrain model was developed in GT-Suite following the 2026 FIA technical directives. Particular attention was given to Articles 5.4.7 to 5.4.10, which define key constraints on hybrid operation: a maximum variation of 4 MJ in battery state of charge, up to 9 MJ of recoverable energy per lap, and a peak MGU-K electrical power output of 350 kW. The model includes updated architecture specifications, active aerodynamic modules, energy deployment logic, and component-level constraints. Telemetry data from the 2024-2025 qualifying sessions was employed for model development, validation, and benchmarking, enabling performance comparisons under realistic track conditions. Analysis results reveal notable deviations in powertrain response and vehicle performance across a range of circuits, establishing a correlation between the powertrain performance and track layouts. The model enables the decomposition of overall system effects into discrete contributions from specific regulatory requirements and individual component limitations. This paper will propose a justification and scheme for developing circuit-specific strategies based on maximum energy constraint and vehicle performance.]]></description>
      <pubDate>Thu, 30 Apr 2026 16:39:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2691995</guid>
    </item>
    <item>
      <title>Numerical simulation of the effect of combustion characteristics in a high-compression-ratio lean-burn gasoline engine utilizing a two-stage water injection strategy</title>
      <link>https://trid.trb.org/View/2663670</link>
      <description><![CDATA[High compression ratios and lean burning were recognized as effective strategies to enhance the thermal efficiency of engines. However, knocking phenomena often impose constraints on further efficiency improvements in engines with high compression ratios. In this paper, computational fluid dynamics (CFD) was employed to simulate the combustion characteristics of an ultra-high compression ratio (CR = 17) gasoline engine with an Atkinson cycle. Meanwhile, single and two-stage water injection strategies were proposed to address the knocking of lean burn engines. Knocking could apparently be suppressed by direct water injection; specifically, the two-stage water injection strategy depicted a better cooling influence caused by evenly distributed water vapor. The two-stage injection strategy resulted in a 105 K reduction in cylinder temperature compared to no water injection. Moreover, this strategy effectively mitigates the deleterious effects of water injection on the initial flame kernel formation and flame propagation, thereby reducing ignition delay time and duration of combustion. Notably, the water injection efficiency of the two-stage water injection strategy is about four times higher than that of the single water injection strategy.]]></description>
      <pubDate>Tue, 28 Apr 2026 17:06:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2663670</guid>
    </item>
    <item>
      <title>Experimental study on the effects of two-stage direct water injection in-cylinder on combustion characteristics of high compression ratio lean-burn engine</title>
      <link>https://trid.trb.org/View/2663665</link>
      <description><![CDATA[Addressing the global energy crisis and environmental challenges, the development of efficient and clean internal combustion engine technology has become a critical research focus. A two-stage direct water injection in-cylinder (DWI) strategy was proposed to address the issues of knocking and combustion stability in high compression ratio (CR = 17) lean burn gasoline engines. The effects of no injection, single and two-stage DWI on the engine under stoichiometric (λ = 1.0) and lean-burn (λ = 1.4) conditions were also investigated experimentally. The experimental results show that under stoichiometric combustion conditions, the two-stage water injection can significantly suppress knocking by optimizing the second-stage water injection timing (60°CA BTDC), reducing the knocking intensity (KI) to 0.17 bar. Under lean-burn, the single water injection strategy demonstrates a better knocking suppression effect. The two-stage water injection strategy effectively controls the coefficient of variation of indicated mean effective pressure (COVIMEP) below 2.57%, which is 0.4% lower than the single water injection strategy. In terms of thermal efficiency, the lean-burn combined with the water injection strategy increases the indicated thermal efficiency to 43.53%. Regarding emission characteristics, CO₂ emissions are mainly dominated by the λ value, and the water injection strategy has a minor impact. The water injection technology can significantly reduce NOₓ emissions. Under stoichiometric combustion conditions, two-stage water injection reduces NOₓ emissions by 45.4% (to 1305.87 ppm), and under lean-burn conditions, it further reduces them to 454.17 ppm. Notably, single water injection shows the best NOₓ control effect under lean-burn conditions, with the emission maintained at around 300 ppm.]]></description>
      <pubDate>Mon, 27 Apr 2026 16:17:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2663665</guid>
    </item>
    <item>
      <title>Efficient Multi-Parameter Optimization of a Twist Beam Rear Axle for Electric Vehicles Using TOPSIS Method for Durability</title>
      <link>https://trid.trb.org/View/2669787</link>
      <description><![CDATA[This study investigates the parameter optimization of a Rear Twist Beam (RTB) for an electric vehicle (EV) during the early stages of product development. Adapting an RTB design from an Internal Combustion Engine (ICE) vehicle platform presents several challenges, one of the challenges is accommodating increased rear vehicle load while minimizing cost, with maintaining existing rear hard points. To address this, we employed an experimental study for Computer-Aided Engineering (CAE) using the Taguchi DOE, which avoids costly physical durability tests. The key design parameters considered were the thickness and material grade of the RTB's components, specifically the cross beam, trailing arms, and reinforcements while preserving their original shapes. L8 Orthogonal array is constructed to design the experiment and identify the influence of the design parameters on durability performance, and the optimal combinations for maximizing durability are identified by using TOPSIS multi objective method. This approach offers significant cost savings by avoiding different iterative physical testing during vehicle development stage. The study found that while changes in the thickness or material of components had mere effect on the rear axle's stiffness, the thickness of the cross beam and trailing arms significantly impacted its durability under various loads.]]></description>
      <pubDate>Mon, 27 Apr 2026 15:01:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/2669787</guid>
    </item>
    <item>
      <title>Ultra-Low NOx Technologies for Heavy-Duty Applications with Reduced Total Cost of Ownership</title>
      <link>https://trid.trb.org/View/2692026</link>
      <description><![CDATA[The utilization of gasoline engines in heavy-duty vehicles for the purpose of continental transportation is in direct competition with conventional diesel engines. It’s imperative that the operating performance of the gasoline engine is equivalent to the diesel engine, and that the gasoline engine shows efficiency benefit to both cost segments, the product manufacturing costs and total cost of ownership (TCO). The 11.6-liter gasoline engine developed has been designed and applicated in such a way that it operates at a stoichiometric combustion air ratio (λ = 1) across the entire engine map range without exception. In combination with external exhaust gas recirculation (EGR) this strategy does not result in a substantial decrease in the absolute NOx concentration in raw emissions compared to the diesel engine with 15.0-liter displacement, but it facilitates the cost-efficient utilization of the three-way catalyzer as the main exhaust aftertreatment system, thereby reducing NOx emissions to the detection limit. This reduction is necessary for adherence to the stringent future emission standards for heavy trucks that are being established by the U.S. regulatory authorities (EPA; CARB) for model years commencing in 2027. In addition to the stoichiometric operating strategy, the engine features an innovative combustion chamber geometry, including a high compression ratio, high EGR compatibility within the real engine operating range, and an optimized crankshaft drive. This already tested technology package is now being applied to heavy-duty engines, proving its scalability and effectiveness. Its application to heavy-duty engines not only promises significant production cost savings but also ensures compliance with future emission regulations. By integrating high EGR rates and high compression ratio, the engine achieves optimal combustion efficiency, thereby minimizing emissions without compromising performance. The engine efficiency is demonstrated by its brake thermal efficiency of 43.1% and an extended map range with a specific consumption of less than 200 g/kWh. In a real heavy-duty driving cycle, the average consumption is 228 g/kWh (vs. 217.5 g/kWh), resulting in a significant reduction in total operating costs on the American market using gasoline as fuel.]]></description>
      <pubDate>Mon, 27 Apr 2026 15:01:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/2692026</guid>
    </item>
    <item>
      <title>Effects of intake areas and shapes on the flow field of elliptical rotary engines at different speeds</title>
      <link>https://trid.trb.org/View/2663662</link>
      <description><![CDATA[Due to the special structure, the flow field of elliptical rotor engines (ERE) shows several flow direction reversals, which is important for ERE working. In this research, a three-dimensional simulation model of ERE was developed using the CONVERGE. The turbulence model was validated through Particle Image Velocimetry (PIV) experiments, allowing for an analysis of the scavenging process. Additionally, the study explored the impact of rotational speed, intake port areas and intake shapes on the flow field within the combustion chamber. The findings reveal that complex flows with multiple directional changes is occurred during the exchange process. With the increase of rotational speed, the volumetric efficiency of ERE increases and then decreases, and the highest point occurs at 4000 rpm. The peak of TKE occurs in the early stage of intake stroke at low rotational speeds, and occurs in the high rotational speed when the port is directly aligned with the recess. Variations in the shape of the intake port change the distribution of gas flowing, with regular trapezoidal and elliptical ports enhancing the swirling intensity in the bottom of the chamber. The elliptical intake port exhibits higher flow intensity at low speeds, while the regular trapezoidal intake port has higher flow strength at high speeds. An increase in the port area intensifies the swirl at the bottom of the chamber while simultaneously reducing the peak TKE. The in-cylinder flow of an elliptical rotor engine can be improved by using an appropriate intake shape and intake area, which improves its working process.]]></description>
      <pubDate>Mon, 27 Apr 2026 15:00:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/2663662</guid>
    </item>
    <item>
      <title>Study on the effect of structural optimization of TCD combustion chamber on engine performance under plateau environment</title>
      <link>https://trid.trb.org/View/2691727</link>
      <description><![CDATA[The geometry of diesel engine combustion chamber directly affects the fuel atomization and combustion process. In order to meet the increasingly stringent emission regulations, this study took a certain model of diesel engine as the object, and used AVL FIRE 2020 R1 software to optimize the geometry of the prototype ω-type combustion chamber under the premise of unchanged compression ratio (CR). A TCD (T: turbocharged, C: charger air cooling, D: diesel particulate filter) combustion chamber with center boss structure and protrusion structure was designed, and the structural parameters of the TCD combustion chamber were further optimized. The computational fluid dynamics (CFD) method was used to analyze the effects of different combustion chamber geometries on the performance and emission characteristics of diesel engines. The results show that the combustion performance of the TCD combustion chamber is mainly affected by the combustion chamber diameter. Too large or too small a combustion chamber diameter will reduce the indicated power. The indicated power of the optimized TCD combustion chamber is 0.98% higher than that before optimization, and 8.26% higher than that of the ω-type combustion chamber. In addition, the soot emissions of the optimized TCD combustion chamber are reduced by 67.33% compared with the design before optimization, and 88.46% compared with the ω-type combustion chamber.]]></description>
      <pubDate>Mon, 27 Apr 2026 14:58:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/2691727</guid>
    </item>
    <item>
      <title>A Short Review of Ammonia Compression Ignition Engines for an SOFC-ICE Power Plant for Shipping</title>
      <link>https://trid.trb.org/View/2580011</link>
      <description><![CDATA[Ammonia is considered one of the most promising hydrogen and energy carriers for decarbonizing deep-sea shipping and other remote heavy-duty applications. The AmmoniaDrive power plant concept uniquely combines Solid-Oxide Fuel Cell (SOFC) and Internal Combustion Engine (ICE) technology to address the issue of how to convert e-ammonia, produced from renewable resources, into useful on-board power safely and effectively, without the need for fossil fuels as combustion promotor. This paper introduces the AmmoniaDrive concept, outlines the challenging combustion properties of ammonia and ammonia-hydrogen mixtures and provides a short review of Compression Ignition ICE research for ammonia-fuelled engines. Three promising combustion concepts are introduced to give direction to further numerical and experimental research.]]></description>
      <pubDate>Thu, 23 Apr 2026 09:11:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2580011</guid>
    </item>
    <item>
      <title>Electrochemical Processes and Energy Systems Towards Step-Wise Emission Reduction of Marine Transport</title>
      <link>https://trid.trb.org/View/2580008</link>
      <description><![CDATA[The consortium of the NAUTILUS project is developing a pilot marine genset, consisting of a Solid Oxide Fuel Cell (SOFC) coupled with a battery and to be hybridized with the existing liquefied natural gas (LNG)-fueled Internal Combustion Engine (ICE) generators. The concept enables a step wise scale-up and integration through mild hybridization, balanced hybridization and full replacement of the ICEs. A demonstrator of the genset of 60 kW is being developed which will be validated at the German Aerospace Center (DLR). The project is aiming a technology that has the potential to reduce CO2 emissions by at least 40% and particulate emissions by 99% in a vessel meeting the targets of the International Maritime Organization (IMO) of 2030. For emission targets beyond 2030, the potential of NAUTILUS genset with synthetic fuels is evaluated. To enable such transition, the reformer unit is conceived to be separated from SOFC power blocks.]]></description>
      <pubDate>Thu, 23 Apr 2026 09:11:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2580008</guid>
    </item>
    <item>
      <title>Real-World Methane Emissions Measured On-Board Two LNG-Fueled Vessels</title>
      <link>https://trid.trb.org/View/2580005</link>
      <description><![CDATA[Real-world studies on-board newbuild vessels powered by modern liquefied natural gas (LNG) engines were conducted at several load conditions at-sea and in harbor. Compared to earlier on-board studies, the methane slip variation was suppressed, and lower methane levels could be achieved at lower engine loads as well. Further reduction in methane slip could be achieved with engine piloting a new combustion concept. Measured results could be reproduced with the STEAM Ship Traffic Emission Assessment Model utilizing new parametrization for methane. Studying the normal operation of two LNG vessels (Ro-Pax (roll-on/roll-off passenger) ferry and a cruise ship) exhibits different engine use profiles of the vessels and may help to identify opportunities to further reduce methane slip by operational choices of the vessels.]]></description>
      <pubDate>Thu, 23 Apr 2026 09:11:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2580005</guid>
    </item>
    <item>
      <title>Redefining Tractor Braking: An Automation-Based Approach for Safety and Efficiency Across Global Applications</title>
      <link>https://trid.trb.org/View/2691808</link>
      <description><![CDATA[Agriculture sector is undergoing a phenomenal transformation, driven by the legislative requirements mandated by countries worldwide to tackle global warming through stringent global emission and on the need to improve operator safety, productivity, particularly on sloped and uneven terrains. Conventional tractors with internal combustion engines (ICEs) have been in use for decades but they often have issues over coordinated control on inclined terrains, especially during load transitions, start-stops, and loader operations. Due to which operators have a critical task of maintaining vehicle stability, controlling rollback on gradients — leading to compromised efficiency, safety risks, and increased fatigue. Global Emission Norms are getting stringent and the justification to end user on the Incremental value proposition is getting difficult to make the products appealing. To address these multifaceted challenges, this paper presents the architecture and functional strategy to increase the productivity & safety of tractor operators through automation of Braking related tasks. This concept is designed in such a way that it can be deployed in multiple power train options. A key innovation explored is the automation of One side braking done in headland turns which helps to completely get rid of Skill and expertise in increasing the productivity. Another interesting feature is Hill Hold functionality where a spring-applied hydraulically released (SAHR) cylinder is used. Hill Hold through E-motor-based torque has also been explored for deployment of the similar solution to deliver much improvised solution in alternate power train. Solution discussed has been designed to meet stringent braking regulations worldwide and has been tested to confirm the same. Automation of One side braking has resulted in Fuel savings & increased productivity and test results confirm savings of about INR 23000 due to fuel and INR 37000 due to increased productivity.]]></description>
      <pubDate>Thu, 23 Apr 2026 09:11:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2691808</guid>
    </item>
    <item>
      <title>Project 030: National Jet Fuels Combustion Program – Area #6: Referee Swirl-Stabilized Combustor Evaluation and Support</title>
      <link>https://trid.trb.org/View/2688779</link>
      <description><![CDATA[This project will develop, conduct, and analyze combustion experiments for alternative jet fuels in the National Jet Fuel Combustion Program’s referee combustor. The effort involves rig testing of combustion parameters as well as implementation of advanced laser and optical measurements in the referee combustor to provide insight into details of the combustion process and provide data for new predictive combustion models under ASCENT Project 028. The goal of this research is to simplify alternative fuel certification procedures by reducing the need for full-scale engine testing. It is part of the National Jet Fuels Combustion Program and will satisfy Area #6, Referee Swirl-Stabilized Combustor Evaluation and Support.]]></description>
      <pubDate>Wed, 22 Apr 2026 10:45:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/2688779</guid>
    </item>
    <item>
      <title>Project 28 Area 4: Combustion Model Development and Evaluation</title>
      <link>https://trid.trb.org/View/2688777</link>
      <description><![CDATA[This project is developing computational tools needed to evaluate alternate fuel combustion in a spray combustion system. The configuration chosen for final study is a subscale Referee combustor designed to investigate lean blow out (LBO) as a function of alternate fuel properties. The computational task requires development of reduced reaction kinetics for these fuels, spray fuel properties and integration into a large-eddy simulation (LES) solver. This project developed a reduced reaction kinetic model and investigated techniques for kinetics acceleration and then applied these models into an LES solver model. The Referee rig is simulated for 3 different fuels for both near blow out (NBO) and LBO. Analysis of the simulations identified critical needs for proper boundary conditions characterization and inclusion of multi-component fuel properties. Although later studies were funded by NASA (in Years 2-3), the initial study under this project demonstrated the viability of LES to study such fuel dependent kinetics in a complex gas turbine combustor.]]></description>
      <pubDate>Wed, 22 Apr 2026 10:45:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/2688777</guid>
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