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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=PHNlYXJjaD48cGFyYW1zPjxwYXJhbSBuYW1lPSJzdWJqZWN0bG9naWMiIHZhbHVlPSJvciIgLz48cGFyYW0gbmFtZT0idGVybXNsb2dpYyIgdmFsdWU9Im9yIiAvPjxwYXJhbSBuYW1lPSJsb2NhdGlvbiIgdmFsdWU9IjAiIC8+PC9wYXJhbXM+PGZpbHRlcnM+PGZpbHRlciBmaWVsZD0ic2VyaWFsIiB2YWx1ZT0iJnF1b3Q7Sm91cm5hbCBvZiBBZXJvc3BhY2UgRW5naW5lZXJpbmcmcXVvdDsiIG9yaWdpbmFsX3ZhbHVlPSImcXVvdDtKb3VybmFsIG9mIEFlcm9zcGFjZSBFbmdpbmVlcmluZyZxdW90OyIgLz48L2ZpbHRlcnM+PHJhbmdlcyAvPjxzb3J0cz48c29ydCBmaWVsZD0icHVibGlzaGVkIiBvcmRlcj0iZGVzYyIgLz48L3NvcnRzPjxwZXJzaXN0cz48cGVyc2lzdCBuYW1lPSJyYW5nZXR5cGUiIHZhbHVlPSJwdWJsaXNoZWRkYXRlIiAvPjwvcGVyc2lzdHM+PC9zZWFyY2g+" 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>
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    <item>
      <title>A dynamic event triggered approach based finite time trajectory tracking of UAV</title>
      <link>https://trid.trb.org/View/2643326</link>
      <description><![CDATA[The problem of altitude and attitude tracking problem of nonlinear quad rotor type unmanned aerial vehicles (QUAV) is addressed by dynamic event-triggered based nonsingular terminal sliding mode control (TSMC) scheme. In order to achieve fast reaching of desired trajectories in presence of unknown disturbances and uncertainties, nonsingular terminal sliding surface is defined. Moreover, the superior performance is achieved with limited resource of computation and communication channel band width by using dynamic event-triggered (DET) strategy. Fast convergence of tracking errors for the proposed control strategy is ensured via Lyapunov stability. The Zeno phenomena is proved to be excluded through precise analysis for the proposed dynamic event-triggered based TSMC scheme. The effectiveness of DET mechanism is examined over static and time triggered implementation of TSMC law for QUAV system.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2643326</guid>
    </item>
    <item>
      <title>Dynamics modeling and control design of the helicopter elastic slung-load system</title>
      <link>https://trid.trb.org/View/2655794</link>
      <description><![CDATA[A mathematical model of the helicopter carrying an external slung load is built based on the multiple-mass-point hypothesis. The equilibrium states along variable configurations are sought through numerical optimization, while the eigenvalue distribution reveals the open-loop stability characteristics. To alleviate the degradation of flight control efficiency caused by load oscillations, a movable hook beneath the fuselage is introduced to provide auxiliary inputs for the underactuated system and stabilize the load motion. A hierarchic control is designed utilizing the state feedback-based nonlinear dynamic inversion (NDI) incorporated with the augmentation device. Considering that the acting point of the sling force on the helicopter is variable and the deviation from the original model appears, the inversion system for each control loop is constructed and combined with the sliding mode control (SMC) to compensate for inversion model errors. Simulation results indicate that the load pendulum motions are rapidly suppressed during forward and circular flights under automatic control. Meanwhile, the helicopter maintains high-fidelity command tracking. Furthermore, the system robustness is validated through the simulations in external disturbances.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2655794</guid>
    </item>
    <item>
      <title>Analysis of bullet-resistant performance and weight optimization for civil aircraft cockpit doors</title>
      <link>https://trid.trb.org/View/2655791</link>
      <description><![CDATA[This paper examines the shortcomings of current civil aircraft cockpit doors in resisting penetration from light firearms. We analyze and optimize the bullet-resistant capabilities of the cockpit door to ensure compliance with airworthiness standards while minimizing structural weight. Using the ABAQUS finite element analysis software, we constructed a dynamic bullet impact model for the cockpit door. Our comprehensive analysis of the door’s bullet-stopping performance under various impact scenarios includes examining the effects of impact angle, velocity, and door material on its bullet-resistant properties. We introduced lightweight, energy-absorbing materials and employed surrogate modeling alongside Latin Hypercube Sampling methods to determine optimal material combinations and thicknesses. These efforts aim to reduce the door’s weight while fulfilling airworthiness bullet-resistance requirements. This paper serves as a valuable reference for subsequent practical engineering applications in bullet-resistant design for cockpit doors.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2655791</guid>
    </item>
    <item>
      <title>Configuration bifurcations in axisymmetric vector exhaust nozzle (AVEN) and their adverse effects on vector deflection certainty</title>
      <link>https://trid.trb.org/View/2655790</link>
      <description><![CDATA[An axisymmetric vectoring exhaust nozzle (AVEN) driven by a 3-SPS/3-PRS parallel manipulator is designed to universally vector the exhaust flow of a variable-geometry Laval nozzle (VGLN) surrounded by multiple groups of convergent and divergent flaps suspended by RSRR kinematic chains. The inherent singularities in parallel manipulators cause the 3-SPS/3-PRS parallel manipulator and the RSRR kinematic chains to produce configuration bifurcations, deeply hidden in parallel manipulators and difficult to perceive. They cause the mobile platform not to be controlled by the input parameters at the bifurcation points, leading to disastrous consequences to the flight safety and control reliability of the parallel manipulator applied in the aerospace field. To explore the configuration bifurcation characteristics concealed in the VGLN and RSRR kinematic chains, the joint coordinate variables of the RSRR kinematic chains and the output parameters of the VGLN are employed as bifurcation variables. The configuration bifurcation points corresponding to these bifurcation variables have been marked on their respective configuration curves using the extended equation and the homotopy method. This study reveals, for the first time, the adverse effects of the bifurcation behaviors associated with the RSRR kinematic chains and the VGLN on the gained singular movements and the flight safety of jets equipped with the AVEN. By analyzing the generating mechanisms of singular movements at the kinematic joints in the bifurcation points, several constructive suggestions are proposed to enhance the flight safety and control reliability of the AVEN.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2655790</guid>
    </item>
    <item>
      <title>Research on obstacle avoidance path planning for multiple UAVs in complex terrain based on an improved ant colony algorithm</title>
      <link>https://trid.trb.org/View/2655784</link>
      <description><![CDATA[In order to solve the obstacle avoidance path planning problem of multiple UAVs in complex mountainous environments, the ant colony algorithm is combined with the particle swarm algorithm and simulated annealing algorithm to propose a multiple UAV path planning algorithm based on the improved ant colony algorithm (PS-ACO-SA) to solve the path planning problem of multiple UAVs in power inspection. To ensure that multiple UAVs can complete the power inspection task efficiently, we designed a collaborative inspection model and transformed the path planning into an optimization problem that includes inspection efficiency, obstacle avoidance and other safety operation requirements and constraints by establishing a cost function. Secondly, the pheromone-related factors of the ant colony algorithm are adjusted, and the influence of the optimal path is enhanced by combining individual fitness to improve the path planning effect. The particle swarm algorithm is integrated to adjust the learning factor to improve the global search ability and speed, and the simulated annealing algorithm is introduced to increase the diversity of solutions. In order to evaluate the performance of the PS-ACO-SA algorithm, six different terrain scenarios are designed for verification. The results show that this method can improve the algorithm’s search ability, convergence speed, robustness and solution quality, and can also find better paths.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2655784</guid>
    </item>
    <item>
      <title>Multi-objective optimization of lateral flight control law: A posteriori approach</title>
      <link>https://trid.trb.org/View/2672692</link>
      <description><![CDATA[This paper presents a novel approach for the multi-objective optimization of flight control law design, utilizing an a posteriori method. Due to the diversity of aircraft flight control law design objectives, the design process is highly complicated, requiring a powerful approach for the simultaneous handling of multiple objectives and direct adaptation of design metrics and criteria. In this paper, we apply a multi-objective optimization procedure including reference point based algorithm to flight control design problem. This procedure aims to identify a set of approximate non-dominated solutions representing a trade-off between different objectives and to provide a well-prepared input for the decision-making stages. The applied approach enhances the efficiency of the design process by utilizing the principles of a posteriori methods to identify an optimal solution. The results for a selected Pareto optimal solution are reported, highlighting the effectiveness of the applied multi-objective optimization procedure.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2672692</guid>
    </item>
    <item>
      <title>Cycle model matching of a regional aircraft engine using high-fidelity flight simulator data</title>
      <link>https://trid.trb.org/View/2672688</link>
      <description><![CDATA[A thermodynamic cycle model was matched to the CF34-8C5B1 engine using the data of a high-fidelity Level-D flight simulator as a surrogate. Before the model match, the data from the simulator was assessed to determine thermal stability, data reproducibility, and engine-to-engine variation. A series of tests were performed across the flight envelope of the MHI CRJ-700 regional aircraft to match and validate the intended cycle model. A baseline off-design cycle model was established based on an engine design point from previous research. This baseline model allowed the detection of any suspicious data obtained from the flight simulator and made it possible to determine appropriate actions concerning the model match. The baseline thermodynamic model was then adjusted and calibrated to match the data from the simulator at various flight conditions. The cycle model adjustments involved: (1) recalibration of the speed lines of the fan map, and (2) tuning the low-pressure turbine map’s adiabatic efficiency. These variables were selected based on the physics of the problem. Moreover, a simplified matching method was proposed, which allows to optimize the processing time and circumvent convergence problems. The proposed adjustments render a final model that predicts the thrust and engine fuel flow rate of the CF34-8C5B1 engine within ±5.0% relative to the flight simulator engine model for the power settings of interest.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2672688</guid>
    </item>
    <item>
      <title>Rapid trajectory optimization for hypersonic vehicles based on line search sequential convex programming</title>
      <link>https://trid.trb.org/View/2668513</link>
      <description><![CDATA[For the hypersonic vehicle reentry rapid trajectory optimization problem, a sequential convex programming method based on a line search algorithm is proposed. The original nonlinear optimal control problem is transformed into a convex optimization problem through convexification and discretization, and then solved using sequential convex programming. To reduce linearization error, a transformation is applied to decouple path constraint variables. To improve convergence, a golden section line search algorithm is designed and integrated into the sequential convex programming framework. Unlike traditional backtracking line search methods, the golden section strategy avoids the need for gradient computations, thereby relaxing the requirement for differentiable objective functions and improving computational efficiency with a predefined convergence interval. In addition, a terminal constraint compensation mechanism is introduced to address the “pseudo-optimal solutions” issue caused by the line search. Simulation results demonstrate that the proposed method is both effective and fast, achieving solution times more than 10 times shorter than conventional trajectory optimization methods. Comparative experiments further validate the advantages of the golden section line search algorithm in reducing iterations and enhancing convergence speed.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2668513</guid>
    </item>
    <item>
      <title>Investigation of the performance of a bifurcated turboprop engine inlet with propeller interference</title>
      <link>https://trid.trb.org/View/2668506</link>
      <description><![CDATA[The aerodynamic interaction between propeller slipstreams and bifurcated turboprop inlets is not yet fully understood, particularly concerning swirl distortion dynamics and unsteady pressure fluctuations caused by rotating propeller interference. This study combines wind tunnel experiments with sliding-mesh CFD simulations to investigate propeller-induced flow interference. High-frequency unsteady pressure sensors and five-hole probes with a 15° stepwise rotation were used to measure time-averaged and transient flow characteristics. Results indicate that increasing the propeller pitch angle from 40° to 50° raises the total pressure recovery coefficient σ by 0.25% but also increases the total pressure distortion DC60 by 40.4%. Similarly, increasing the propeller speed from 1500 r/min to 2000 r/min enhances σ by 0.34% while causing DC60 to rise by 51.4%. The propeller interference increases the swirl distortion., limiting swirl intensity to 3.43° at 4048 r/min under propeller rotation. This represents a 12.1% increase compared to the 3.06° swirl intensity observed when the propeller is absence. A dominant frequency of 240.3 Hz, corresponding to the blade-passing frequency of the 8-bladed propeller at 1800 r/min, was identified in the wall pressure fluctuations, confirming periodic flow interactions. These findings provide experimental and numerical evidence of the mechanisms behind propeller-induced swirl distortion in bifurcated inlets. The methodology and results directly support the design of advanced turboprop engines requiring improved aerodynamic stability and foreign object exclusion capabilities.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2668506</guid>
    </item>
    <item>
      <title>A multi-factor flight delay prediction and evaluation method based on artificial neural network and cloud model</title>
      <link>https://trid.trb.org/View/2681268</link>
      <description><![CDATA[The purpose of this paper is to combine the cloud model method with the Artificial neural network to predict and evaluate flight delay date. In this paper, the flight delay data of the United States in recent 15 years were collected, involving nine airlines and seven delay causes. Then, the flight delay prediction model is obtained by combining neural network and cloud model theory. 36 sets of data are extracted to verify the accuracy of the prediction model. Finally, the delay rate is predicted and the prediction data is evaluated by cloud model. The results show that the amount of data to be processed is reduced to 20 % after combining the cloud model with the neural network. In the model validation, the average expected value deviation of flight delay prediction model is 23.1 %. In the analysis and evaluation of the prediction results, the delay cause 6 is taken as an example, with the highest delay rate of 7.03 % in December. The delay risk assessment results for all months were general. The method provided in this paper can predict flight delays and provide theoretical support for the delay prevention of airlines.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2681268</guid>
    </item>
    <item>
      <title>Emergency evacuation assessment of blended-wing-body aircraft based on dynamic risk model: A comparative study</title>
      <link>https://trid.trb.org/View/2681264</link>
      <description><![CDATA[The high passenger capacity and multi-compartment structure of Blended-Wing-Body (BWB) aircraft introduce new challenges for emergency evacuation. However, existing airworthiness standards, which are established based on conventional tube-and-wing aircraft, primarily assess safety through overall evacuation time, overlooking the dynamic propagation of risks in fire scenarios. To address this limitation, this study develops a fire-coupled occupant evacuation model and proposes a dynamic risk assessment framework that integrates cabin layout, evacuation pathways, and fire dynamics. By comparing the evacuation performance of a 380-seat BWB aircraft and an A350-900 under identical fire intensity conditions, the study suggests a potential for enhanced evacuation safety performance of the BWB configuration, attributed to its ability to effectively mitigate heat radiation and toxic gas dispersion. Furthermore, the conventional assessment model is refined by introducing a coupled criterion between the dynamic risk index Rh and the Required Safe Egress Time (RSET), improving the robustness of localized risk evaluations. This method provides theoretical support for optimizing BWB cabin layouts and designing effective emergency response strategies.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2681264</guid>
    </item>
    <item>
      <title>A method for solving trajectory optimization problems with multiple no-fly zone constraints using direct collocation</title>
      <link>https://trid.trb.org/View/2681263</link>
      <description><![CDATA[When solving trajectory optimization problems with no-fly zone constraints using direct collocation, both the number of constraints and the number of non-zero elements in the Jacobian matrix escalate rapidly as the number of no-fly zones increases. To address this issue, this paper presents a method for solving trajectory optimization problems with multiple no-fly zone constraints. This method consolidates multiple no-fly zone constraints into a single path constraint, thereby maintaining a consistently low level of constraints and non-zero elements in the corresponding Jacobian matrix, even as the number of no-fly zones increases. It is also proved theoretically that the Karush-Kuhn-Tucker (KKT) solution of the nonlinear programming (NLP) problems before and after the handling are equivalent. The effectiveness of the proposed method is validated through three numerical examples involving multiple no-fly zone constraints. A comparison with the ordinary method for handling no-fly zone constraints is implemented, which confirms the superiority of the proposed method in improving the solving efficiency.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2681263</guid>
    </item>
    <item>
      <title>Conceptual design and analysis of an affordable truss-braced wing regional jet aircraft</title>
      <link>https://trid.trb.org/View/2681262</link>
      <description><![CDATA[A regional, turbofan-powered, 72-passenger, transport aircraft with very high aspect ratio truss-braced wings is developed with an affordable methodology from an existing 52 passenger, conventional twin-turboprop aircraft. At first, the ration behind the selection of the truss-braced wing configuration is discussed. Next, the methodologies for the sizing, weight, aerodynamics, performance, and cost analysis are presented and validated against existing regional aircraft. The variant configurations and their design features are then discussed. Finally, sensitivity analysis is carried out to investigate the effects of the wing aspect ratio and engine bypass ratio on the aircraft weight, aerodynamics, and cost. It has been found that the penalties associated with the wing weight will prevent the acceptable realization of the high aspect ratio wing benefits, but when it is combined with the very high bypass ratio engines, a 17% reduction in the mission fuel weight is achieved. In contrast, the cost analysis has revealed that the application of higher aspect ratio wings in the truss-braced wing configuration may increase the development and maintenance costs. Consequently, with aspect ratios higher than 24, eventually, these costs may outperform the associated fuel cost reductions.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2681262</guid>
    </item>
    <item>
      <title>Enhancing communication efficiency in solar UAVs: A rigorous design method with deformable configuration</title>
      <link>https://trid.trb.org/View/2681261</link>
      <description><![CDATA[Solar-powered unmanned aerial vehicles (SPUAVs) serve as effective airborne base stations, leveraging their extended endurance and high cruising altitudes for wide-ranging communication services. Despite their potential, the design space for SPUAVs is constrained, necessitating an innovative approach to enhance their efficiency. This paper presents a rigorous design methodology for SPUAVs incorporating deformable configurations, aiming to optimize photovoltaic energy harvesting efficiency. We established a comprehensive model encompassing communication and energy balance. Subsequently, a heuristic algorithm is engaged to identify the optimal parameters. Simulation results demonstrate that, while expanded communication coverage necessitates increased mass allocation (exemplified by a 150% mass escalation from 120 kg to 300 kg), the implementation of deformable configuration demonstrates substantial mass efficiency improvements, which can achieve up to a 17% reduction in total weight. This study provides valuable insights into enhancing the operational capabilities of SPUAVs, offering a balanced perspective on design considerations for energy efficiency and mission effectiveness.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2681261</guid>
    </item>
    <item>
      <title>Data-Efficient Machine Learning for Airfoil Prediction via Targeted Data Augmentation</title>
      <link>https://trid.trb.org/View/2706286</link>
      <description><![CDATA[Optimizing airfoil geometry is critical for improving rotorcraft efficiency by directly influencing blade lift and drag forces. However, the inherent nonlinearity of fluid dynamics and the high dimensionality of design space make airfoil geometry optimization a challenging task. This study proposes a machine learning (ML) approach to predict key aerodynamic coefficients: drag (Cd), lift (Cl), and moment (Cm) as a faster alternative to computational fluid dynamics (CFD) simulation. Because ML model performance depends heavily on the training data, generating large CFD data sets is computationally expensive. To address this, we investigated how training data set size and composition affect the predictive accuracy of ML models, aiming to reduce data needs without compromising performance. These models are intended to serve as efficient surrogates for future airfoil optimization. We constructed three data sets with increasing quantities of maximum thickness (t=0.5) data points: the Initial data set (containing none), Data set_1 (Initial data set + 5,000), Data set_2 (Initial data set + 30,000). For each data set, separate ML models were trained to predict Cd, Cl, and Cm, resulting in nine models in total: Cx_T0, Cx_T5k, and Cx_T30k, where Cx∈{Cd,Cl,Cm}. To assess the impact of t=0.5 data, we evaluated the models on two test sets: Testset_1 (excluding t=0.5) and Testset_2 (only t=0.5). Results show that adding more t=0.5 training data improved accuracy on Testset_2, but marginally reduced performance on Testset_1. Among the models, Cx_T5k models strike the best balance: they surpassed Cx_T30k on Testset_1 and performed slightly worse on Testset_2, despite being trained on significantly fewer points. These results highlight the value of targeted data augmentation in reducing training data requirements and computational cost while maintaining predictive performance, thereby supporting efficient ML-based airfoil optimization.]]></description>
      <pubDate>Thu, 28 May 2026 09:06:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/2706286</guid>
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