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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Heat Flux Measurements in the Ohio State University Rate of Heat Release Apparatus</title>
      <link>https://trid.trb.org/View/2694504</link>
      <description><![CDATA[A copper slug calorimeter was used to measure the cold-wall heat flux and the convective heat transfer coefficient in the Ohio State University (OSU) Rate of Heat Release Apparatus specified in Federal Aviation Regulation (FAR) 25.853(a-1). The copper slug calorimeter is an American Society for Testing and Materials (ASTM) primary standard used for measuring the heat flux of radiant energy sources (ASTM E 662) and oxyacetylene torches (ASTM E 457). In contrast to the Gardon Heat Flux Sensor, the slug calorimeter provides an absolute measurement of heat flux and does not require calibration. The average convective heat transfer coefficient is obtained from the transient response of the slug calorimeter and is potentially useful as a system diagnostic since it is sensitive to air flow rate, temperature, and turbulence within the OSU chamber. Slug calorimeter construction, measurement of the heat transfer coefficient, and both global and local (e.g., at the impinging pilot flame) heat fluxes incident on the sample are discussed. The accuracy and reproducibility of sample heat fluxes are compared to those obtained with a Gardon Heat Flux Sensor. On average, the heat flux measured with an optimal copper slug calorimeter, when taking into account the absorptivity of the black surface coating, is within experimental error of the value measured with a National Institute of Standards and Technology (NIST) calibrated Gardon Heat Flux Sensor.]]></description>
      <pubDate>Tue, 12 May 2026 10:25:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2694504</guid>
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    <item>
      <title>Root cause analysis of airplane technical failures with Rasmussen's risk management framework (RRMF) based human-machine-environment-procedure (HMEP) taxonomy</title>
      <link>https://trid.trb.org/View/2670179</link>
      <description><![CDATA[This study developed a taxonomic approach based on 30 technical failure occurrences between 2002 and 2020. This framework extends the author's previous work on human-machine-environment-procedure (HMEP) taxonomy through the application of Rasmussen's Risk Management Framework (RRMF), which can serve as a common framework to aggregate or compare datasets collected by different organizations. This RRMF-based HMEP taxonomy was used to categorize the contributing factors of 30 technical failure occurrences into seven mutually exclusive categories and respective subcategories for statistical analysis and other risk management analysis. The RRMF provided a hierarchical structure for these first-layer categories, including government oversight, manufacturer deficiency, company management, company procedure and documentation, people and activity management, technical failure, and environment. The functional block diagram and failure modes and effects analysis (FMEA) were applied to translate the technical failures of 12 environment control system failure cases into FMEA tabular statements. Several failure modes had been identified for environmental control system failure occurrences, e.g., sense line leakage, flawed sensor input, duct crack and leakage, broken part (pin and spring), seal degradation, contamination, tube rupture, mechanical joining defect, poor contact, and unanticipated failure instances for electronic centralized aircraft monitor (ECAM). Each failure mode can provide diagnostic information to identify and fix the environmental control system failure problem more effectively. In conclusion, this RRMF-based HMEP taxonomy provided a mental model to guide the data collection during an accident investigation and subsequently derive accident patterns as the core for Safety Management System (SMS) implementation.]]></description>
      <pubDate>Tue, 12 May 2026 09:11:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/2670179</guid>
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    <item>
      <title>HEEFO: A Lightweight Cryptographic Trinity for Robust UAV Communication Security</title>
      <link>https://trid.trb.org/View/2694612</link>
      <description><![CDATA[Unmanned Aerial Vehicles (UAVs) communication systems face significant security issues due to stringent computational limitations and real-time operational demands. Conventional cryptography methods such as RSA and standard Elliptic Curve Cryptography (ECC) entail computing demands that are incompatible with resource-constrained UAV platforms. We introduce HEEFO, an innovative lightweight cryptographic system that seamlessly combines Hyperelliptic Curve Cryptography (HECC), Electric Eel Foraging Optimization (EEFO), and Blockchain technology to mitigate these limitations. Our Hybrid AES-HECC method produces a 15 ×  faster key generation as compared to standard ECC with the same level of 80-bit security. The EEFO algorithm optimizes cryptographic key lengths with 7 ×  and 6.5 ×  speedup over Genetic Algorithm (GA) and Particle Swarm Optimization (PSO), reducing memory consumption by 15%. Blockchain integration guarantees unalterable authentication records with the ability for dynamic key rotation. Thorough security validation by Automated Validation of Internet Security Protocols and Applications (AVISPA) formal verification and attack simulations demonstrates 100 % resistance against man-in-the-middle, tampering, counterfeiting, and brute-force assaults. The performance study indicates enhanced efficiency, with energy consumption at 20.3 mJ and communication overhead at 1472 bits, reflecting a 13–55% improvement compared to current authentication techniques. Real-world validation of the UAV testbed during a 5-hour test demonstrated that the system achieved success rates between 94 and 100 %, throughput of 17 to 23 messages per second, and optimal use of resources (CPU: 20–40 %, RAM: 25–35%) which resulted in only a 5.5 % loss of flight time. This research is intended to provide practical methods for using lightweight cryptography on resource-constrained UAV networks to enable secure communication in real-time without degrading operational performance.]]></description>
      <pubDate>Mon, 11 May 2026 17:11:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2694612</guid>
    </item>
    <item>
      <title>Joint Beamforming and Resource Allocation Design for STARS-Assisted UAV-Enabled ISCC Network</title>
      <link>https://trid.trb.org/View/2698632</link>
      <description><![CDATA[With the development of wireless networks, integrated sensing, computing, and communication (ISCC) has emerged as a pivotal direction for the sixth-generation communication system. In this paper, a full-coverage simultaneously transmitting and reflecting surface (STARS)-aided unmanned aerial vehicle (UAV)-enabled ISCC framework is proposed, where a multi-functional UAV simultaneously provides edge computing services to users and performs target sensing. In particular, to improve the computation efficiency of the system, a multi-tier computing (MTC) framework is proposed, in which the UAV can further offload computation tasks to a powerful cloud server (CS). Based on this structure, the weighted sum computation rate is maximized by jointly optimizing the transmit beamformer, STARS coefficients, and computing resource allocation between the UAV and CS. To tackle this tricky problem, we first transform the radar SINR constraints into a manageable form and then propose an iterative block coordinate descent (IBCD) algorithm based on weighted minimum mean square error (WMMSE). Finally, the numerical results validated the effectiveness of the proposed algorithm and indicated that 1) when UAV resources are limited, utilizing the MTC structure can significantly enhance the system’s computation rate, and 2) compared with the traditional RIS, the proposed STARS scheme demonstrates superior performance in the ISCC network.]]></description>
      <pubDate>Mon, 11 May 2026 17:11:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2698632</guid>
    </item>
    <item>
      <title>A Novel MDP Decomposition Framework for Scalable UAV Mission Planning in Complex and Uncertain Environments</title>
      <link>https://trid.trb.org/View/2698630</link>
      <description><![CDATA[This paper presents a scalable and fault-tolerant framework for unmanned aerial vehicle (UAV) mission management in complex and uncertain environments. The proposed approach addresses the computational bottleneck inherent in solving large-scale Markov Decision Processes (MDPs) by introducing a two-stage decomposition strategy. In the first stage, a factor-based algorithm partitions the global MDP into smaller, goal-specific sub-MDPs by leveraging domain-specific features such as goal priority, fault states, spatial layout, and energy constraints. In the second stage, a priority-based recombination algorithm solves each sub-MDP independently and integrates the results into a unified global policy using a meta-policy for conflict resolution. Importantly, we present a theoretical analysis showing that, under mild probabilistic independence assumptions, the combined policy is provably equivalent to the optimal global MDP policy. Our work advances artificial intelligence (AI) decision scalability by decomposing large MDPs into tractable subproblems with provable global equivalence. The proposed decomposition framework enhances the scalability of Markov Decision Processes, a cornerstone of sequential decision-making in artificial intelligence, enabling real-time policy updates for complex mission environments. Extensive simulations validate the effectiveness of our method, demonstrating orders-of-magnitude reduction in computation time without sacrificing mission reliability or policy optimality. The proposed framework establishes a practical and robust foundation for scalable decision-making in real-time UAV mission execution.]]></description>
      <pubDate>Mon, 11 May 2026 17:11:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2698630</guid>
    </item>
    <item>
      <title>Energy-Aware Joint Task Assignment and 3D Path Planning for Cooperative Multi-UAV Networks</title>
      <link>https://trid.trb.org/View/2696992</link>
      <description><![CDATA[Unmanned Aerial Vehicle (UAV) networks have emerged as a pivotal solution for mobile sensing tasks in complex civilian and military environments. Compared with single-UAV systems, multi-UAV collaboration offers significant advantages, including superior robustness against single-point failures and enhanced efficiency in multi-target sensing. However, coordinating such networks in 3D environments with known threats presents significant challenges, particularly due to the complex coupling between high-level task allocation and low-level trajectory planning. To address these challenges, we propose a hierarchical collaborative optimization framework that effectively decouples the spatio-temporal constraints into two interlinked layers. First, we introduce an extended Hungarian algorithm tailored for asymmetric costs to ensure global optimality in task allocation. Second, we develop a novel bio-inspired Self-Evolved Artificial Bee Colony (SE-ABC) algorithm to generate safe, energy-efficient 3D trajectories dynamically. In contrast to many recent hybrid or learning-based planners that typically rely on offline training and extensive parameter tuning, SE-ABC offers a training-free and lightweight evolutionary search with self-adaptive operators, enabling online trajectory refinement under coupled energy–threat costs while remaining easy to implement and interpret. We validated the proposed framework using a DJI Phantom 3 quadcopter prototype and extensive simulations. Experimental results demonstrate that our approach significantly outperforms existing benchmarks, such as Particle Swarm Optimization (PSO), Genetic Algorithm (GA), and the standard Artificial Bee Colony (ABC). On average, the proposed method reduces the total mission cost by 15% (accounting for safety), shortens path length by 23%, and decreases task completion time by 25%.]]></description>
      <pubDate>Mon, 11 May 2026 17:11:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2696992</guid>
    </item>
    <item>
      <title>Intermixing Cells in an Aircraft Nickel-Cadmium Battery</title>
      <link>https://trid.trb.org/View/2694498</link>
      <description><![CDATA[Tests were performed at the Federal Aviation Administration William J. Hughes Technical Center by the Fire Safety Team of the Airport and Aircraft Research and Development Group to determine if intermixing different manufacturer cells within an aircraft nickel-cadmium battery has an effect on battery performance and if any such effect results in a safety of flight issue. A series of tests from RTCA/DO-293 were conducted on two batteries, one consisting of all original equipment manufacturer (OEM) cells, and one consisting of ten OEM and ten Part Manufacturer Approval (PMA) replacement cells. The tests included several rated capacity tests, a charge stability test, a duty performance test, and an induced destructive overcharge test. Throughout the tests, only slight differences between the OEM and intermixed batteries were observed. The PMA cells consistently charged at a higher voltage; however, none of the cells exceeded the maximum voltage of 1.7 V. During some tests, individual cells showed some differences in behavior and recorded battery temperatures. The most notable difference occurred during the induced destructive overcharge tests, in which a larger number of cells from the intermixed battery recorded increased voltage readings, indicating signs of thermal runaway. The results show no indication of any safety of flight issues arising from the intermixing of OEM and PMA battery cells within a nickel-cadmium aircraft battery.]]></description>
      <pubDate>Mon, 11 May 2026 15:25:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/2694498</guid>
    </item>
    <item>
      <title>An Investigation of the Vertical Bunsen Burner Test for Flammability of Plastics</title>
      <link>https://trid.trb.org/View/2694499</link>
      <description><![CDATA[A vertical Bunsen burner test for flammability of plastics (UL-94V) was studied in an attempt to relate the upward burning of plastics to their material fire properties. It was shown that the heat release parameter, the critical heat flux for piloted ignition, and the thermal response parameter account for most of the fire behavior of plastics in the test. The premixed flame of the Bunsen burner during transient ignition and the laminar diffusion flame of the burning material have nominal heat fluxes of about 60 kW/m². The heat release rate (HRR) per unit area during burning was a significant factor in correlating UL-94V ratings. The height of the flame, which transfers heat to the burning sample, was proportional to HRR, and critical values of HRR for ignition, sustained burning, and upward flame spread in the test were theoretically estimated to be 80, 250, and 300 kW/m², respectively.]]></description>
      <pubDate>Mon, 11 May 2026 15:25:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/2694499</guid>
    </item>
    <item>
      <title>Simulating the Distribution of Halon 1301 in an Aircraft Engine Nacelle with HFC-125</title>
      <link>https://trid.trb.org/View/2694497</link>
      <description><![CDATA[The primary fire suppressant used in commercial aircraft engine nacelles and auxiliary power units is Halon 1301. The period of fire suppression system development and its certification testing may be an arduous task requiring the discharge of substantial quantities of fire suppressant. Additionally, to demonstrate compliance with federal regulations, engine nacelle fire suppression systems are discharged in flight or at varying conditions simulating flight. These tests are recorded and evaluated with specialized gas analysis equipment. Currently, the certification process requires releasing Halon 1301 to accomplish such approvals. Based on the Montreal Protocol and its amendments, the halon family of fire suppressants has been eliminated from production. This action is in response to the destructive capacity of halon with respect to the ozone layer within the atmosphere. This technical note describes a procedure for utilizing an ozone-friendly chemical to simulate the Halon 1301 discharge characteristics during fire suppression system development and certification testing. It demonstrates a realistic potential to eliminate the release of Halon 1301 for purposes other than actual fire suppression. This step is perceived as an interim process to assist with the reduction of Halon 1301 release during the transition to chemicals which meet the intent of the Montreal Protocol.]]></description>
      <pubDate>Mon, 11 May 2026 14:42:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2694497</guid>
    </item>
    <item>
      <title>Enhancing Expressway Crash Rescue with Vertical Takeoff and Landing Vehicles: Insights from an Evolutionary Game Study</title>
      <link>https://trid.trb.org/View/2701227</link>
      <description><![CDATA[Expressway traffic crashes often result in higher fatalities and more severe congestion compared with incidents on regular roads, creating significant challenges for timely emergency response. Vertical takeoff and landing (VTOL) vehicles offer a potential solution to bypass surface-level bottlenecks and efficiently deliver emergency personnel and supplies. This study develops a tripartite evolutionary game model to analyze the strategic interactions among crash participants, VTOL operators, and road authorities in the context of expressway rescue. The analysis identifies the most favorable equilibrium as one where point-to-point rescue is adopted, VTOL services are actively provided, and road conditions are effectively managed. This setup encourages coordination among stakeholders and enhances overall rescue efficiency. The evolutionary path is affected by factors such as road regulation costs, subsidy coefficients, and stakeholders’ initial willingness to cooperate. Notably, higher initial cooperation from crash victims and VTOL operators accelerates convergence toward stable outcomes. These findings improve understanding of the feasibility conditions for VTOL deployment in emergency scenarios and guide cost-sharing mechanisms, stakeholder alignment, and policy design to support the practical implementation of VTOL-based rescue strategies.]]></description>
      <pubDate>Mon, 11 May 2026 12:24:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2701227</guid>
    </item>
    <item>
      <title>Development of an Integrated Small Aircraft Runway Length Analysis Tool</title>
      <link>https://trid.trb.org/View/2701141</link>
      <description><![CDATA[The Federal Aviation Administration Advisory Circular (AC) 150/5325-4B provides the current method for estimating runway length requirements in airport design. The design curves and necessary runway length adjustments published two decades ago may not reflect the performance of many new-generation aircraft operating in the National Airspace System. Moreover, this AC offers limited information about the trade-offs between runway length, useful load, and mission range. This paper presents an integrated computer model called the Small Aircraft Runway Length Analysis Tool (SARLAT) to improve the existing methodology. The SARLAT incorporates 76 individual aircraft performance characteristics based on robust data processing, consolidation, and validation workflow. A regression-based model has been developed to account for nonzero runway gradients and different runway surface conditions. An analysis indicates that the current design curves are conservative for modern mid-size and super mid-size business jets, but cannot accommodate light jets, consequently constraining operators’ operational flexibility and possibly reducing airport revenue. SARLAT provides aircraft stage length and payload-range analysis to assist airport designers and improve decision-making. The stage length analysis estimates the cumulative distribution of distances flown by individual aircraft in the United States. Using a time-step numerical simulation, SARLAT includes payload-range analysis to quantify the trade-offs between the aircraft’s useful load and mission range. Finally, SARLAT determines the critical aircraft operation at the airport based on runway length and geometric design requirements. Since SARLAT leads to more accurate and cost-effective estimates of runway length requirements, the FAA plans to mandate the use of this tool in the Airport Improvement Program.]]></description>
      <pubDate>Mon, 11 May 2026 12:24:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2701141</guid>
    </item>
    <item>
      <title>Taxonomy of threats, security mechanisms, and regulatory frameworks for cargo delivery drones</title>
      <link>https://trid.trb.org/View/2666409</link>
      <description><![CDATA[Cargo drones promise to revolutionize logistics by providing efficient and eco-friendly delivery solutions for goods, including medical supplies and hazardous materials. However, the rapid integration of this technology brings significant security challenges, such as cyberattacks, drone hijacking, and regulatory hurdles. This article presents cargo drones’ substantial threats and vulnerabilities, focusing on cybersecurity risks and physical security issues. It also discusses future directions, emphasizing the need for robust security frameworks and regulatory measures to ensure safe and secure drone operations. The aim is to balance fostering innovation and safeguarding public safety and supply chain integrity. In addition to security concerns, broader challenges are encountered by the logistics sector in adopting drone technology. Discoursing these challenges is essential, as the findings of this research present valuable insights for practitioners and researchers seeking to apply new technologies effectively within the logistics landscape.]]></description>
      <pubDate>Mon, 11 May 2026 08:50:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/2666409</guid>
    </item>
    <item>
      <title>From volatility to concentration: Spatio-temporal heterogeneity and evolution in global freighter networks</title>
      <link>https://trid.trb.org/View/2697082</link>
      <description><![CDATA[Freighter aircraft play a critical role in shaping the spatial organisation of global air cargo flows, yet existing research offers limited insight into their network structure and temporal behaviour. Prior studies rely heavily on annual snapshots, regional analyses, or integrator-focused data, leaving the dynamics of general cargo carriers largely unexplored. This paper addresses these gaps by constructing the Worldwide Freighter Network (WFN), a unique global dataset covering 327 consecutive weeks (2018–2024) and including both scheduled and charter operations for 24 major freighter airlines. Using a temporally granular network framework, we examine how freighter connectivity patterns persist, reconfigure, and concentrate across space over time. We analyse the evolution of freighter networks at both global and airline levels, providing the first temporally granular, airline-specific analysis of global freighter network dynamics. The results reveal a persistent shift toward greater spatial concentration and gateway dominance after the COVID-19 shock, indicating a structural reorganisation of the global air cargo system rather than a temporary disruption. Beyond this system-wide transition, airline-level analysis reveals substantial heterogeneity in network design, routing logic, and temporal stability, underscoring that global connectivity patterns obscure diverse carrier-specific strategies. Overall, the findings highlight the importance of spatio-temporal resolution for interpreting the spatial structure, resilience, and evolution of global freight transport networks as well as for individual airlines.]]></description>
      <pubDate>Thu, 07 May 2026 11:02:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2697082</guid>
    </item>
    <item>
      <title>The Governance and Regulations of Unmanned Aircraft Systems in the European Union – A Comparative Framework</title>
      <link>https://trid.trb.org/View/2580068</link>
      <description><![CDATA[Unmanned aircraft systems (UAS) have witnessed a radical increase in a variety of applications. While delivering obvious benefits, there are also hazards and risks regarding, for example, physical safety, people’s privacy, and cyber security. The regulatory framework on UAS was considerably changed due to the adoption of Regulation (EU) 2018/1139, which, as a centralised, top-down regulation, covers nearly all UAS, regardless of their weight and size. Although the ensuing regulations and guidelines from the European Commission and European Aviation Safety Agency (EASA) give detailed provisions for things like the operation and design of UAS, the implementation of said rules and the necessary procedures involved are up to the member states and their competent authorities. This paper compares current differences in selected member states considering the implementation of new UAS regulations. The results imply that there is a wide variability between member states in how they cover different aspects of the new regulation. This paper also draws preliminary conclusions on the maturity of the governance and regulatory framework.]]></description>
      <pubDate>Wed, 06 May 2026 15:22:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/2580068</guid>
    </item>
    <item>
      <title>Capturing the true bounding boxes: vehicle kinematic data extraction using unmanned aerial vehicles</title>
      <link>https://trid.trb.org/View/2596546</link>
      <description><![CDATA[This paper presents a methodology by which kinematic variables of road vehicles can be extracted from unmanned aerial vehicle (UAV) footage. The oriented bounding boxes of the vehicles are identified based on the aerial view of the intersection, and the kinematic variables, such as position, longitudinal velocity, lateral velocity, yaw angle and yaw rate, are determined. The bounding boxes are converted to the perspective of a roadside camera using homography, to generate labeled data sets for training the machine learning-based perception systems of smart intersections. Compared to ordinary GPS data-based technology, the proposed method provides smoother data and more information about the dynamics of the vehicles. In the meantime, it does not require any additional instrumentation on the vehicles. The extracted kinematic variables can be used for motion prediction of road traffic participants and for control of connected automated vehicles (CAVs) in intelligent transportation systems.]]></description>
      <pubDate>Wed, 06 May 2026 15:21:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/2596546</guid>
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