<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <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" />
    <description></description>
    <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>
    </image>
    <item>
      <title>Analysis of Operational Factors Contributing to Aircraft Overflight Noise Variation</title>
      <link>https://trid.trb.org/View/2685625</link>
      <description><![CDATA[Significant variations in measured overflight noise are observed from airport monitor networks, even for similar aircraft flying comparable operational procedures. Operational factors, including aircraft configuration, acceleration and deceleration procedures, thrust profiles, and associated environmental factors, can impact noise. To assess these impacts, operational Automatic Dependent Surveillance–Broadcast surveillance and weather data were associated with noise monitor recordings for a 3-year period at Seattle-Tacoma and John Wayne International Airports for Boeing 737-800, Boeing 737-700, and Airbus A320 aircraft. The impact of flight procedures on noise observations is assessed by evaluating flight profiles by airline to investigate the impact of differences in departure and arrival procedures. It was observed that aircraft weight and thrust correlate positively with noise on departure. At John Wayne Airport, there is evidence that thrust variations can result in large differences in noise near the airport, while procedural differences, such as a steeper initial climb seen at both airports, can reduce noise levels at further distances. Noise on arrival was observed to correlate more closely with airspeed and shows evidence of being dependent on aircraft flap configuration.]]></description>
      <pubDate>Thu, 09 Jul 2026 13:29:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/2685625</guid>
    </item>
    <item>
      <title>Predictive modeling of BLDC motor performance in UAV systems using ensemble learning</title>
      <link>https://trid.trb.org/View/2702880</link>
      <description><![CDATA[Accurate prediction of thrust and torque is essential for optimizing the performance, energy efficiency, and control of brushless direct current (BLDC) motors in unmanned aerial vehicles (UAVs). Traditional physics-based models often struggle to capture the nonlinear relationships between motor input parameters and aerodynamic outputs, prompting the exploration of data-driven approaches. This study evaluates the predictive capabilities of six ensemble learning algorithms, including Bootstrap Aggregating (Bagging), Adaptive Boosting (AdaBoost), Gradient Boosting Machine (GBM), Extreme Gradient Boosting (XGBoost), Categorical Boosting (CatBoost), and Stacked Generalization (Stacking), in modeling thrust and torque. Experimental data were obtained using a Tyto Robotics thrust stand designed for precise static performance testing of electric propulsion systems. Among the models, CatBoost exhibited the highest accuracy in thrust prediction with a coefficient of determination of 0.9873, a root mean square error (RMSE) of 7.0506, a mean absolute error (MAE) of 6.0610, and a mean absolute percentage error (MAPE) of 2.10%. In torque prediction, AdaBoost demonstrated superior performance, achieving an R2 of 0.9713, RMSE of 0.0018, MAE of 0.0013, and MAPE of 2.60%, effectively capturing complex electromechanical dynamics. In contrast, XGBoost underperformed in thrust prediction due to hyperparameter sensitivity, while Stacking showed limited generalization in torque estimation. Bagging and GBM delivered moderate and consistent results across both outputs. The findings underscore the potential of CatBoost and AdaBoost for robust predictive modeling of UAV propulsion systems, contributing to enhanced control and system design in autonomous flight applications.]]></description>
      <pubDate>Tue, 30 Jun 2026 09:45:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2702880</guid>
    </item>
    <item>
      <title>Hybrid Physics-Informed Neural Network and PID Control for Fault-Tolerant Autonomous Multi-Copters</title>
      <link>https://trid.trb.org/View/2712153</link>
      <description><![CDATA[This paper addresses the critical challenge of fault-tolerant control in autonomous multi-copters, particularly under conditions of one or two rotor failures a scenario that often leads to severe instability and a complete loss of directional control due to unbalanced torque and resultant autorotation. Existing advanced control strategies, including optimal approaches such as LQR, typically require precise system modeling and state estimation, which are difficult to achieve in real-world, dynamic failure scenarios. Alternative methods like fuzzy logic, sliding mode control, and gain-scheduling either lack robust generalization or are impractical for enumerating all possible failure cases. In this work, a hybrid control framework integrating Physics Informed Neural Networks (PINN) with a standard PID controller is proposed for fault-tolerant operation of autonomous multi-copters subject to multiple actuator failures. PINNs incorporate governing physical laws as regularization in their loss functions, allowing them to learn optimal counter-torque actions and thrust balancing necessary to arrest autorotation and stabilize flight, despite limited training data and uncertainty in failure conditions. The calculated moments and thrust commands are executed via a robust PID scheme, enabling reliable real-time implementation and minimizing residual oscillations. This hybrid control architecture demonstrates significant potential to enhance the resilience and operational safety of autonomous multi-copters during unexpected motor failures. By leveraging PINN’s physics-based generalization and PID’s consistent execution, the proposed method offers an adaptive, model-agnostic approach for maintaining stable flight and directional control under severe actuator faults, with implications for next-generation fault-tolerant UAV systems deployed in complex environments.]]></description>
      <pubDate>Tue, 23 Jun 2026 13:32:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2712153</guid>
    </item>
    <item>
      <title>Effect of Strap-On Geometry on the Aerodynamics of Multibody Launch Vehicle</title>
      <link>https://trid.trb.org/View/2712110</link>
      <description><![CDATA[Strap-on boosters play a crucial role in heavy launch vehicles by providing additional liftoff thrust without major changes to the baseline design, enabling launch with existing propulsion systems. However, strap-on boosters introduce additional pressure drag and alter the overall aerodynamics of the vehicle. While efforts have been previously made to derive empirical relationships to predict the aerodynamics of different strap-on configurations, most are case-specific and primarily limited to estimating drag coefficients (CD). The present study focuses on geometric parameters of strap-on such as length, diameter and radial gap between strap-on and core. The results are used to derive an empirical relationship which can be applied during preliminary design stage of a launch vehicle to predict axial force coefficient (CA), normal force coefficient (CN) and pitching moment coefficient (CPM), which are required for mission design and structural load estimation. In the current study, systematic CFD based parametric studies were conducted using Reynolds-averaged Navier-Stokes based in-house solver PARAS 3D. Simulations were performed at transonic (Mach=1.2) and supersonic (Mach=1.8) regimes in pitching condition at an angle of attack 4°. The study considers a simplified configuration with two parallel strap-on boosters. Parameters were evaluated relative to a clean-core baseline configuration. An empirical relation between aerodynamic coefficients and strap-on geometry was derived and were validated against different configurations. The derived relations provide a rapid and practical tool for preliminary aerodynamic assessment of multibody launch vehicles.]]></description>
      <pubDate>Wed, 10 Jun 2026 17:08:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/2712110</guid>
    </item>
    <item>
      <title>Dynamically coupled path planning and feedforward-enhanced sliding mode control for underactuated Unmanned Surface Vehicles</title>
      <link>https://trid.trb.org/View/2710089</link>
      <description><![CDATA[While autonomous marine systems have advanced rapidly, conventional hierarchical planning and control architectures for underactuated unmanned surface vehicles (USVs) often suffer from dynamic mismatches. Geometric planners may generate paths that are difficult to execute physically, forcing downstream controllers into reactive tracking and increasing actuator burden. To address this issue, this paper proposes a thrust–moment coupled kinodynamic planning and feedforward-enhanced control framework. In the planning layer, a physics-informed one-dimensional sampling manifold is constructed in the constrained surge–yaw control-input space, allowing the planner to incorporate the underactuated maneuvering characteristics of USVs, especially the reduction of surge thrust during high-yaw maneuvers. The resulting full-state reference trajectories are dynamically compatible and provide position, velocity, and acceleration information for control. In the control layer, a full-state feedforward integral non-singular terminal sliding mode controller combined with a nonlinear disturbance observer is designed to exploit high-order reference states and compensate for disturbances and model uncertainties. Simulations show that the proposed method achieves sub-meter-level tracking accuracy with substantially lower computational latency than MPC. A prototype experiment further provides preliminary physical validation of the proposed framework.]]></description>
      <pubDate>Tue, 09 Jun 2026 14:36:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2710089</guid>
    </item>
    <item>
      <title>Numerical investigation of passive and active hydrofoils mounted on a ship's bow for thrust generation and fuel efficiency</title>
      <link>https://trid.trb.org/View/2707679</link>
      <description><![CDATA[Nowadays, reducing fuel consumption and protecting the environment are two key challenges in marine engineering. This study investigates the effects of bow-mounted hydrofoils (passive and active) on ship resistance, thrust generation, and fuel efficiency using Computational Fluid Dynamics (CFD). Numerical results are validated against experimental data to ensure accuracy. The outcomes show that the hull with an active hydrofoil demonstrates superior performance, achieving a 16.43% reduction in total resistance, a 15.39% decrease in fuel consumption, and a 3.79-fold increase in hydrofoil-generated thrust compared to the passive hydrofoil. However, the hull with a passive hydrofoil shows more limited effects, such as a 3.03% reduction in both resistance and fuel consumption relative to the bare hull. These improvements are attributed to favorable interactions between the hull, hydrofoil, and waves, as well as bow motion reduction and additional thrust generation. A sensitivity analysis is also performed to evaluate the influence of wave parameters (wavelength, wave height) and hydrofoil characteristics (aspect ratio, active hydrofoil rotation amplitude). The results provide insights into the optimal design of active hydrofoils for fuel-efficient ship operations in regular waves.]]></description>
      <pubDate>Fri, 29 May 2026 15:37:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2707679</guid>
    </item>
    <item>
      <title>Flight Safety Control and Test Flight Experiments under Single-Engine Failure</title>
      <link>https://trid.trb.org/View/2608081</link>
      <description><![CDATA[The complex airflow in low-altitude environments increases the difficulty of flight control for small and medium-sized aircraft after engine failure. To reduce the impact of wind disturbances on the wind vane during flight tests, this paper proposes a heading channel lateral acceleration control method based on active disturbance rejection control (ADRC). The control law is specifically optimized for asymmetric thrust conditions and uses lateral acceleration data from the inertial navigation system as feedback. Monte Carlo simulation results validate the robustness and effectiveness of the proposed controller in handling asymmetric thrust conditions. A series of semiphysical simulations demonstrate the controller’s effectiveness during single-engine failure in the takeoff, cruise, and landing phases. Finally, flight tests further confirm the practicality and stability of the control law under complex conditions. This method provides a promising solution to enhance the flight safety of small and medium-sized aircraft in low-altitude single-engine failure scenarios.]]></description>
      <pubDate>Wed, 27 May 2026 13:09:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/2608081</guid>
    </item>
    <item>
      <title>Neural network based fault identification for quadrotor thrust loss and propeller misalignment</title>
      <link>https://trid.trb.org/View/2691027</link>
      <description><![CDATA[This paper proposes a neural network (NN) based fault identification technique for thrust loss and propeller misalignment. The proposed identification method is demonstrated using a quadrotor, and the stabilization is achieved using standard proportional, derivative, and integral controller. First, the fault is introduced into the quadrotor mathematical model, and then a database is created to train the NN. In the first case, the NN model to identify the thrust loss and location of rotor failure is developed. The idea is to assign the thrust loss to each rotor and then train the NN using thrust loss and rotor speed. In the second case, the propeller misalignment NN model also has been developed. The idea here is to assign the misalignment to each rotor that is responsible for the additional yaw. This results in a difference in diagonally placed pair rotor speed. The contribution of this paper is the fault identification method that is suggested, where fault classification and type are established after the NN is trained using misalignment angle and rotor speed. Simulation results reveal that, by taking the rotational speed of all four rotors as input, the trained NN determines the percentage of thrust loss and propeller misalignment angle.]]></description>
      <pubDate>Thu, 21 May 2026 16:28:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2691027</guid>
    </item>
    <item>
      <title>Hull wake asymmetries in dynamic maneuvering for a twin-shaft ship: A new CFD informed formulation</title>
      <link>https://trid.trb.org/View/2692624</link>
      <description><![CDATA[This paper introduces a reduced-order model aimed at describing loading asymmetries on twin shaft propeller ships during generic maneuvers in calm water. While a number of formulations for twin shaft ships exist in the literature, the effects of dynamic maneuvering cases have not been investigated in depth. To inform the proposed model, a series of RANS-based CFD simulations was conducted including both static cases, such as steady drift, and dynamic cases, including pure sway and pure yaw. The new formulation was validated by performing a zigzag maneuver in CFD, where thrust and torque results were compared against those predicted by the formulation. The approach proved to be both effective and computationally efficient, offering a valid reduced-order model for understanding unsteady effects in generic maneuvers.]]></description>
      <pubDate>Thu, 21 May 2026 09:10:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/2692624</guid>
    </item>
    <item>
      <title>Aerodynamic Proximity Effects between the DrivAer and AeroSUV Standard Models, Part 1 – Same-Lane Interactions</title>
      <link>https://trid.trb.org/View/2692050</link>
      <description><![CDATA[In this paper, the effects of aerodynamic interactions on the drag of a longitudinally-arranged two-vehicle system are examined by considering the influence of separation distance, cross winds, vehicle size and shape. Testing was undertaken at 30% scale in a large wind tunnel with road-representative freestream turbulence. Separation distances of 0.5, 1.0, and 2.0 vehicle lengths (L) were examined over a range of yaw angles between ±15°. A highlight of the current study is the characterization of platoon drag-reduction benefits for different sizes and shapes of the lead and follower models, by using a DrivAer model and an Aero-SUV model, each with slant-back (Notchback or Fastback) and square-back (Estateback) variants, providing four distinct model pairings. Drag reduction for the lead model appears to be affected mainly by the size of the follower model, while the follower model shows a much greater sensitivity to shape of the lead model. Larger drag reductions were observed at most distances and yaw angles when the lead model had a slant-back configuration (Notchback or Fastback), with smaller drag reductions observed for lead models with square-back configurations (Estateback). This resulted from the different wake structures and their respective influences on the surface-pressure distributions of the follower model. Thrust sheltering is observed as the dominant cause for increased drag at the shortest separation distance. Most of the data show that the drag reductions for the two-vehicle system were larger when the AeroSUV model followed the DrivAer model. This was due to a combination of the greater proportional drag reduction for the leading DrivAer and to the greater relative weighting of the AeroSUV drag reduction due to its larger reference drag area. Peak system-drag reductions of up to 22% were observed at 0.5L separation, decreasing to 18% at 1.0L and 12% at 2.0L.]]></description>
      <pubDate>Tue, 14 Apr 2026 15:11:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2692050</guid>
    </item>
    <item>
      <title>Integration of a Load Cell in a Hexacopter UAS Failsafe Propulsion Arm for Inflight Thrust Measurement</title>
      <link>https://trid.trb.org/View/2665831</link>
      <description><![CDATA[Accurate thrust measurement of multicopter UAS propulsion systems is necessary across various fields, including for UA performance research as well as in UAS deployment, especially for lifting operations using multirotor unmanned aircraft. This paper details the development of a multicopter propulsion arm with an integrated load cell, capable of measuring the thrust generated by the mounted rotor. Hence the thrust generated by the individual rotors of the hexacopter UA whilst being operated in the open field may be accurately measured and subsequently logged. The mounting adopts a failsafe design that permits the motor to provide the necessary rotor propulsion even when the load cell unit fails, allowing the safe landing of the hexacopter UA and avoiding the loss of the aircraft. The mounting assembly was statically characterized for the load cell response across a range of applied loads. Numerical models for the load cell response were developed, based on a Machine Learning Gradient Boosting Regressor, whilst analytical models based on the Bouc-Wen and Preisach models were also developed. The Machine Learning Gradient Boosting Regressor model returned the closest estimate to the true applied load with a reduction in RMSE of 36.6 % when compared to the raw load cell data.]]></description>
      <pubDate>Mon, 23 Mar 2026 15:15:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665831</guid>
    </item>
    <item>
      <title>Symmetric wake dynamics in rotor biomimetic efficient propulsion</title>
      <link>https://trid.trb.org/View/2637856</link>
      <description><![CDATA[The occurrence and properties of the biomimetic propeller wake are studied by using detached eddy simulations (DES). The efficiency of the propeller is verified in relation to the Strouhal number St. By studying the wake of fish swimmers, the thrust vortex of the propeller is retained, while the drag vortex is weakened. Proposed the biomimetic symmetric rotor vortex: (i) When the vortex characteristics of the rotor wake match the hydrodynamics of fish swimmers, the propulsion efficiency is optimal; (ii) The pressure at the tip and hub of the blade is relatively small, which is conducive to weakening the cavitation phenomenon and has good concealment. (iii) Studying the connection between macroscopic data and fluid mechanics characteristics, the transition of wake mode is an important bridge. Meanwhile, the biomimetic symmetric rotor vortex generated by the new BF-MAU is closer to the biodynamic characteristics, achieving higher efficiency and better concealment, with an efficiency increase of 2.87 %. In addition, linking the efficiency vortices (thrust vortex and drag vortex) with the kinetic energy mechanism, this slight change in kinetic energy provides an important reference for the study of fluid mechanics. The wake behavior of biomimetic explains the most reasonable cause of the wake-vortex interaction.]]></description>
      <pubDate>Wed, 18 Mar 2026 10:11:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/2637856</guid>
    </item>
    <item>
      <title>Preliminary Design and Analysis of a Dual Throat Fluidic Thrust Vectoring Nozzle for Supersonic Aerospace Application</title>
      <link>https://trid.trb.org/View/2669797</link>
      <description><![CDATA[The Dual Throat Nozzle (DTN) is a unique nozzle configuration that enables fluidic thrust vectoring (FTV), improving aircraft maneuverability while reducing the mechanical complexity of traditional vectoring systems. In this study, a two-dimensional DTN was developed based on a validated NASA Langley model, incorporating a newly designed plenum geometry guided by area expansion ratio principles. Numerical simulations were carried out in ANSYS Fluent using a density-based, steady-state solver with the SST k–ω turbulence model to capture key compressible flow features such as shock waves, flow separation, and jet deflection. Secondary injection rates were determined using choked-flow relations, and a 12-case parametric study was conducted to analyze the effects of Nozzle Pressure Ratio (NPR), injection rate, and injection angle on thrust deflection and efficiency. The simulation results at NPR = 4 with 3% injection showed strong agreement with NASA experimental data, validating the computational setup. It was observed that higher NPR values reduced jet deflection but improved overall thrust efficiency, with the best performance achieved at NPR = 2 and a 150° injection angle. The findings provide valuable insight into optimizing DTN design parameters for lightweight, efficient fluidic thrust vectoring systems suited to future supersonic applications.]]></description>
      <pubDate>Tue, 17 Feb 2026 10:28:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2669797</guid>
    </item>
    <item>
      <title>Experimental investigation of bow-mounted passive and active hydrofoils for ship resistance reduction in regular waves</title>
      <link>https://trid.trb.org/View/2648668</link>
      <description><![CDATA[This study experimentally investigates the influence of passive and active bow-mounted hydrofoils on ship-resistance reduction and thrust generation in regular waves. Towing-tank experiments were performed on a Series 60 ship model equipped with both passive and active hydrofoils to quantify their effects on the total resistance. The active hydrofoil system, actuated by a servomechanism, was continuously adjusted in angle of attack in synchronization with the bow's vertical motion, whereas the passive hydrofoil was kept at a fixed angle of attack of zero degrees. Tests were conducted over various forward speeds, wavelength-to-ship-length ratios, and active-hydrofoil oscillation amplitudes to evaluate the influence of these parameters on hydrodynamic performance. The results indicate that the active hydrofoil generated a notable propulsive thrust, achieving up to a 32 % reduction in the mean total resistance compared with the passive configuration. These findings emphasize the superior energy-harvesting potential of active hydrofoils and their promise for reducing ship power demand and fuel consumption. The results support the design and control optimization of wave-interaction devices for ships.]]></description>
      <pubDate>Tue, 03 Feb 2026 10:03:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2648668</guid>
    </item>
    <item>
      <title>Research on the flow evolution and thrust characteristics of underwater thermal jets considering backpressure and nozzle swing angle</title>
      <link>https://trid.trb.org/View/2648663</link>
      <description><![CDATA[This study systematically investigates underwater thermal jet dynamics through integrated test and numerical approaches, examining cavity evolution and thrust performance across varying water depths and nozzle swing angles. The research reveals a characteristic evolution path where secondary jets drive cavity transition from “flattened” through “cap-like” to “ellipsoidal” morphology, while elucidating how interfacial instability is triggered by mixing between low-temperature pre-cavities and high-temperature primary jets. Results demonstrate that increasing ambient back pressure asymmetrically redistributes the jet momentum, suppressing axial cavity growth by up to 49 % while enhancing near-field radial expansion by 32 %, leading to a transition from a slender to a short-broad cavity. Unsteady flow separation and shock oscillations induced by overexpanded jets are identified as the primary source of pressure fluctuations near the nozzle exit. The vehicle base plate suppresses jet buoyancy, inducing flow reversal and periodic back-impacting loads. Flow asymmetry caused by nozzle swing is the key reason for thrust loss and vector control deviation, with 10° deflection producing over 15 % axial thrust loss and radial negative thrust. This study provides theoretical insights and empirical data supporting enhanced physical understanding and performance optimization of underwater propulsion systems.]]></description>
      <pubDate>Tue, 03 Feb 2026 10:03:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2648663</guid>
    </item>
  </channel>
</rss>