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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>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Numerical study of the atomization performance of coaxial and porous injectors in rocket engine applications</title>
      <link>https://trid.trb.org/View/2647094</link>
      <description><![CDATA[The numerical study involved in comparing the atomization performance of coaxial and porous injectors using the coupled volume of fluid and discrete phase CFD model (coupled VOF-DPM). The study focuses on the primary atomization region of the injection. The investigation is done to study the effect of water-air mass flow ratios on droplet parameters such as droplet size (SMD), axial and radial velocity, and the number of droplets at different injection times. Pore-level simulations are performed to study the performance of the porous injectors. It is observed that increasing the water-air mass flow ratio in both types of injectors leads to an increase in droplet size. The results showed that the droplet size produced by the coaxial injector is larger than that of the porous injector. Moreover, the number of droplets produced by the coaxial injector is lower than that produced by the porous injector. The smaller droplet size and larger number of droplets indicate better atomization in the porous injector.]]></description>
      <pubDate>Mon, 30 Mar 2026 08:56:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2647094</guid>
    </item>
    <item>
      <title>Dual-Control Inference Diffusion Model via Multi-Sensor High-Frequency Signal for Space Transportation Engine Anomaly Detection</title>
      <link>https://trid.trb.org/View/2561864</link>
      <description><![CDATA[Liquid Rocket Engine, as the key power device of the space transportation system, the anomaly detection of operation status is the key to its reliable operation. However, in the face of multi-sensor high-frequency monitoring signals under extreme operating conditions, limited by the ability of model data modeling, the existing methods, based on classification and reconstruction strategies, are difficult to further improve the anomaly localization precision. To address the challenges and overcome the limitations of existing methods, this paper proposes a Dual-control Inference Diffusion Model (DIDM), which reconstructs and inferences on specified sensor samples to achieve accurate anomaly detection. The reverse diffusion inference process is controlled by the channel condition and mask prior, combined with two loss functions for alternating training, which enables inference for samples from specified sensors at specific moments. We evaluate the model based on the static ignition test data of a certain type of LRE. The results show that DIDM outperforms the state-of-the-art methods in terms of detection accuracy, which demonstrates the effectiveness and superiority of DIDM. Furthermore, by combining the error distributions of the inference results, we can achieve a more accurate location of anomaly in the time and frequency domains, which could increase the efficiency of rocket launches and air and space transportation, and enhance the potential of the academic results for industrial applications.]]></description>
      <pubDate>Mon, 23 Mar 2026 17:14:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/2561864</guid>
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    <item>
      <title>Air Core Vortexing in Liquid Draining Vessels: Impact of Drain Port Vanes</title>
      <link>https://trid.trb.org/View/2594162</link>
      <description><![CDATA[AbstractVortex formation in liquid propulsion tanks can obstruct propellant flow, reduce discharge efficiency, and cause cavitation in feed pumps, posing a risk to spacecraft and rocket performance. To mitigate these ill effects, intrusive vortex suppression strategies, such as vanes, have been explored. This study experimentally investigates the effect of vanes positioned inside a circular drain port on air-core vortexing in precritical and postcritical height regimes. A newly introduced discharge number quantifies vortex suppression. Experiments are conducted using a liquid draining setup, where vanes of varying configurations are tested under different initial rotation conditions. The study measures the critical height, emptying time, and critical time, while the air-core blockage percentage and static pressure near the drain port are determined analytically to analyze vortex behavior. Results indicate that vanes enhance draining efficiency in the postcritical regime by weakening the air-core vortex but hinder discharge in the precritical regime by increasing frictional resistance. These findings have practical applications in optimizing liquid propulsion systems, ensuring uninterrupted propellant flow, reducing vortex-induced cavitation risks, and improving spacecraft engine performance. Building on these findings, the study suggests implementing a selective electro-mechanical system that deploys vanes only after critical height formation, thereby optimizing fuel management in aerospace propulsion systems.]]></description>
      <pubDate>Wed, 11 Mar 2026 14:44:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2594162</guid>
    </item>
    <item>
      <title>Refractory Metal-Lined Composites for Lightweight High-Performance Propulsion Components</title>
      <link>https://trid.trb.org/View/1787687</link>
      <description><![CDATA[Requirements for advanced rocket propulsion systems are becoming increasingly more demanding. The use of high temperature capable materials in such systems, including applications in liquid rocket engines and solid rocket motors, offers potential benefits of increased performance and/or efficiency based on the engine operating cycle. For the ultimate in high temperature capability, refractory metals, ceramics, ceramic matrix composites (CMCs), and carbon/carbon (C/C)composites each provide particularly beneficial attributes, but with selected limitations. Refractory metals are relatively tough and durable, provide impermeable structures, and can be conventionally fabricated, but are relatively dense, leading to heavyweight structures. Monolithic ceramics generally lack desired toughness and durability. CMCs offer substantially improved toughness over their monolithic counterparts and are relatively lightweight, but are permeable and difficult to join to conventional structures. C/C is extremely lightweight, but lacks resistance to the operating environment and is also permeable. Metal-lined, composite-jacketed structures have the potential to combine the beneficial characteristics of metals with the light weight and high temperature resistance of CMCs or C/C. In the current work, prototype refractory metal-lined C/C structures were designed, fabricated, and successfully ground tested in a representative liquid rocket engine environment. No leakage or permeability was exhibited. Successful joining was achieved to the mating structure, and cost-effective fabrication was demonstrated using an “inside-out” processing technique. Projected full-scale component weight was similar to that for conventional materials employed in similar applications. This approach, when matured, offers the potential for fabrication of lightweight, durable, and cost-effective advanced rocket propulsion components.]]></description>
      <pubDate>Mon, 29 Dec 2025 09:37:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1787687</guid>
    </item>
    <item>
      <title>Gain-Scheduling Robust Control for High-Speed Flat Magnetically Suspended Rotor of MSCMG Considering Gyroscopic Effects and Dynamic Characteristics</title>
      <link>https://trid.trb.org/View/2603973</link>
      <description><![CDATA[This article proposes a gain-scheduling state feedback (GS-SF) control strategy using the tensor product model transformation (TPMT) method. A multichannel dynamic model of the active magnetic bearing (AMB) rotor is established, and then, the characteristics of the gyroscopic effects term varying with rotational speed are analyzed. The linear matrix inequality (LMI) constraints for the controller design are derived while considering disturbances and dynamic performance and further extended to linear parameter-varying (LPV) systems, effectively reducing the conservatism of controller design and the difficulty of parameter adjustment. A GS-SF controller is synthesized using the provided LMIs and compared with the decentralized PID control method. The simulation and experimental results show that the proposed method not only effectively suppresses the strong gyro coupling effect of the AMB rotor, ensuring the stability of the whirling modes, and achieves a suspension accuracy better than 5% of the protection gap at the target speed but also has good disturbance suppression ability and dynamic response performance.]]></description>
      <pubDate>Tue, 02 Dec 2025 09:25:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/2603973</guid>
    </item>
    <item>
      <title>Evaluating risk-based hazard corridors in air traffic controller decisions during space launch failures</title>
      <link>https://trid.trb.org/View/2602058</link>
      <description><![CDATA[The increasing frequency and diversity of space launch activities challenge the safety and reliability of current air traffic management systems. In this study, the authors present a risk-based hazard corridor methodology for managing air traffic during space launch failures. The method combines a debris propagation model with a hazard corridor construction approach that estimates the risk posed by debris to aircraft. The authors evaluated the constructed risk-based hazard corridors using high-fidelity human-in-the-loop simulations. In the experiments, air traffic controllers managed two strategies of hazard corridors. The dynamic hazard corridor updated the boundary in real-time while the static hazard corridor remained fixed by consolidating the dynamic boundaries over the entire activation period until the last piece of debris fell. The results show that controllers maintained safety separation across all scenarios, although their real-time workload increased significantly during hazard corridor activation. Overall, the controllers’ perceived workload and situation awareness remained stable, implying that the task demands were acceptable for all the experimental runs. Efficiency measure results indicate that the dynamic hazard corridor can reduce extra flight distance and delays, thus minimizing operational disruption caused by space launch failures. The authors also found that more experienced controllers tend to choose more cautious and conservative rerouting strategies. These findings offer practical guidance for improving resilience in air and space management integration. Furthermore, the study provides a basis for modeling air traffic controller behavior under emergency conditions in a way that is more in line with the real world patterns.]]></description>
      <pubDate>Wed, 15 Oct 2025 12:30:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/2602058</guid>
    </item>
    <item>
      <title>Study of Crew Seat Impact Attenuation System for Indian Manned Space Mission</title>
      <link>https://trid.trb.org/View/2571748</link>
      <description><![CDATA[The descent phase of Indian Manned Space Mission culminates with a crew module impacting at a predetermined site in Indian waters. During water impact, huge loads are experienced by astronauts. This demands an impact attenuation system which can attenuate the impact loads and reduce the acceleration experienced by astronauts to safe levels. Current state of the art impact attenuation systems uses honeycomb core, which is passive and can only be used once (at touchdown impact) during the entire mission. Active and reusable attenuation systems for crew modules are still an unexplored territory. Three configurations of impact attenuators are selected for this study for the crew module configuration, namely, hydraulic damper, hydro-pneumatic damper and airbag systems. All the subsystems are mathematically modelled, and initial sizes are estimated using Genetic Algorithm and SQP optimization techniques. Semi-active control for Hydraulic and Hydro-Pneumatic dampers are implemented and evaluated against its passive counterpart. An airbag impact attenuation system is studied and its performance in two configurations, stuck and unstuck are evaluated. Venting will not cease for the former configuration, whereas it is pressure controlled for the latter. For zero-degree impact load case, Brinkley DRI (Direct Response Index), a NASA HSIR index on the risk of likelihood of spinal damage, is reduced by 36% for hydraulic damper and 22% for Hydro-Pneumatic damper using semi-active control and 15% for Airbag system. Hydraulic dampers were proven to be superior to Airbag and Hydro-Pneumatic systems within the spatial constraints imposed by the present crew module configuration.]]></description>
      <pubDate>Fri, 18 Jul 2025 09:03:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/2571748</guid>
    </item>
    <item>
      <title>Development of Deployment Mechanism for RAMBHA-LP Payload Onboard Chandrayaan-3 Lander</title>
      <link>https://trid.trb.org/View/2571746</link>
      <description><![CDATA[RAMBHA-LP (Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere—Langmuir Probe) was one of the key scientific payloads onboard the Indian Space Research Organization’s (ISRO) Chandrayaan-3 mission. Its objectives were to estimate the lunar plasma density and its variations near the lunar surface. The probe was initially kept in a stowed condition attached to the lander. A mechanism was designed and realized for deploying the probe at a distance of 1 meter to avoid the plasma sheath effect in the moon’s plasma environment. The RAMBHA-LP deployment system consists of a metallic spherical probe with Titanium Nitride coating on its surface, a long carbon-fiber-reinforced polymer boom, a spring-assisted deployment mechanism, a dust-protection subsystem, and a hold release mechanism (HRM) based on a shape-memory alloy-based actuator. The entire RAMBHA-LP system weighed nearly 1.3 kilograms. The system had undergone many sub-system and system-level tests in ambient, dynamic, and thermo-vacuum environments, simulating interplanetary mission conditions. After completion of all developmental, qualification, and acceptance level tests, the system was integrated with the ‘Vikram’ Lander and launched using ISRO’s Launch Vehicle Mark III (LVM 3) on July 14, 2023. The Chandrayaan-3 lander made history by landing on the lunar south pole on August 23rd, 2023. The RAMBHA-LP payload was successfully deployed the next day. The deployment of the payload was confirmed by two status confirmation switches in the mechanism. This paper describes the design and configuration of the payload deployment mechanical system, with a focus on the design of the various mechanical subsystems, the results of software simulation and analysis, and the details of the large number of tests conducted to make the deployment system ready for the mission.]]></description>
      <pubDate>Fri, 18 Jul 2025 09:03:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/2571746</guid>
    </item>
    <item>
      <title>A Stability Analysis Method for High-Speed Magnetically Suspended Rotors Based on Tensor Product Model Transformation</title>
      <link>https://trid.trb.org/View/2553500</link>
      <description><![CDATA[The stability of whirling modes of high-speed magnetically suspended rotors due to strong gyroscope effects varies with the speed, which is the main factor affecting the stability of the system. In this article, a speed-dependent linear parameter-varying (LPV) model of an active magnetic bearing (AMB) rotor system is derived. Then, an improved tensor product model transformation (TPMT) method is introduced to transform the dynamic model into a tensor product model form on a bounded parameter domain, in which the decomposed vertex systems are further remapped to analyze the stability easily. Moreover, a stability criterion based on dual-frequency Bode diagrams is developed. By analyzing the whirling stability characteristics of each vertex system, the stability judgment and stability margin calculation of the high-speed AMB rotor in the whole speed range can be realized, which effectively reduces the complexity of the radial rotation stability analysis of high-speed magnetically suspended rotors. The results show that this method is a feasible solution to analyze the stability of the parameter-dependent time-varying AMB model.]]></description>
      <pubDate>Wed, 18 Jun 2025 14:41:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2553500</guid>
    </item>
    <item>
      <title>Spray characteristics and combustion mechanism influence on combustion stability of UDMH/NTO pre-combustor under external excitation</title>
      <link>https://trid.trb.org/View/2548014</link>
      <description><![CDATA[To study the combustion stability of liquid rocket engines with hypergolic propellant more comprehensively, external pressure pulse excitation was applied to the UDMH (unsymmetrical dimethylhydrazine)/NTO (methylhydrazine) pre-combustor. The effects of pressure pulse intensity, spray characteristics (droplet diameter and spray cone angle), and combustion mechanism on combustion stability characteristic frequencies and attenuation characteristics after excitation were investigated. The simulation results show that all operation conditions capture the first three longitudinal frequencies of the pre-combustor, and all factors have a greater impact on frequencies with higher orders. Increasing the pulse intensity and reducing the droplet diameter are not conducive to combustion stability. The influence of the spray cone angle on the combustion stability is not monotonous. The pre-combustor has good stability when the spray cone angle is 70°. Different combustion mechanisms have a significant effect on the results before and after pressure pulses, and considering a more complete combustion process may increase the attenuation time in the pre-combustor. The obtained rules can provide a reference for the design and simulation of hypergolic liquid rocket engines, which is beneficial for predicting and evaluating the combustion stability of liquid rocket engines.]]></description>
      <pubDate>Fri, 13 Jun 2025 09:13:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2548014</guid>
    </item>
    <item>
      <title>Attitude Control Method for Liquid-Filled Flexible Spacecraft Based on Wave-Based Control</title>
      <link>https://trid.trb.org/View/2543193</link>
      <description><![CDATA[A spacecraft often consists of a main rigid body, flexible appendages, and liquid loads such as fuel. Precise positioning and fast stabilization are crucial, but the complex interactions among rigid, flexible, and liquid components lead to residual vibrations, which can deteriorate performance, causing undesired effects like jitter, pogo oscillation, or resonance. Specifically, the coupling between fuel slosh and solar panel vibrations challenges control accuracy. This study compares the performance of wave-based and proportional-derivative controllers through numerical simulations of a liquid-filled spacecraft with a flexible appendage during an attitude maneuver in a microgravity environment. Notably, the impact that wave-based control has over the spacecraft attitude maneuvering states is greater than the proportional derivative controller, but requires a decreased control input cost. Comparison with an experiment using linear-quadratic-Gaussian control reveals that wave-based control does not instigate high-frequency vibration even when the correction is abrupt. These findings are valuable for spacecraft modeling, dynamic analysis, and control system design.]]></description>
      <pubDate>Wed, 30 Apr 2025 16:58:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/2543193</guid>
    </item>
    <item>
      <title>Performance enhancement of an annular expansion-deflection nozzle to enhance rocket thrust</title>
      <link>https://trid.trb.org/View/2528490</link>
      <description><![CDATA[As rockets consume a lot of fuel, the rocket nozzle design is critical. This paper explores performance optimization for expansion-deflection nozzles (EDNs) by incorporating a new design modification that includes an additional divergent section. Traditional EDNs experience a marked decline in thrust efficiency at specific nozzle pressure ratios (NPRs) due to the deflection of the supersonic flow near the nozzle exit plane, leading to flow separation and velocity reduction. To address this, the authors propose a strategic enhancement that integrates an additional divergent section designed to delay the onset of flow separation and improve overall efficiency. This design exploits expansion fan dynamics to re-expand and re-attach the flow to the nozzle wall, thereby mitigating efficiency losses. Computational fluid dynamics (CFD) simulations were conducted to evaluate the modified EDN at NPRs of 70, 160, and 200, representing open wake, transition, and delayed closed wake modes, respectively. The results indicate a substantial improvement in thrust efficiency, with the modified design effectively delaying the mode transition and maintaining higher efficiency across a broader range of operating conditions.]]></description>
      <pubDate>Mon, 31 Mar 2025 15:29:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2528490</guid>
    </item>
    <item>
      <title>Soil pollution with jet-fuel by the Russian aerospace transportation</title>
      <link>https://trid.trb.org/View/2525556</link>
      <description><![CDATA[Aviation and space transportation effect the ecosystems since the beginning and middle of 20th century, respectively. However soil pollution with jet fuel is virtually unexplored. In this article, the authors summarized the levels of soil pollution near the airfields (in Central Russia) and in the falling sites of the Soyuz launch vehicle debris (in Central and Northern Kazakhstan) with petroleum hydrocarbons via the concentration of jet fuel and/or total petroleum hydrocarbons. At the long-term used airfields in the central regions of Russia, the level of contamination is acceptable: the authors did not find any jet fuel (its concentration was below 0.1 g/kg – the lowest detected level) in all 47 soil samples collected at the impact zones of 7 airfields. At propellant spills with an area of no >7.1 m² from the regular falling sites of the Soyuz launch vehicle first stages, the content of jet fuel and total petroleum hydrocarbons reached 128 (n = 36; 11 falling sites) and 57 g/kg (n = 2249; 230 falling sites), respectively. Four months after the jet fuel spill at Ostafyevo airfield, there was 190 g/kg of jet fuel in the impact zone. One day after the accident, up to 1.6 g/kg of total petroleum hydrocarbons were found at the site where the Soyuz launch vehicle second stage fell. Ecosystems can get rid of jet fuel pollution in a few years. For Aridisols in Kazakhstan, 0.26 g/kg total petroleum hydrocarbons is proposed as a trigger value. Fluorimetry gives lower results for total petroleum hydrocarbons than chromatography-mass spectrometry. This is probably because of different sample preparation and extraction.]]></description>
      <pubDate>Tue, 25 Mar 2025 16:57:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2525556</guid>
    </item>
    <item>
      <title>Feasibility Study on Handling Lunar Regolith Using Magnetic Force</title>
      <link>https://trid.trb.org/View/2519308</link>
      <description><![CDATA[Lunar regolith is magnetic due to the nanophase iron trapped in the surface rim of the regolith. Therefore, technologies are being developed to capture and transport regolith using magnetic force for future in situ resource utilization on the Moon. However, the lack of detailed data on the magnetic properties of regolith hinders the development of efficient regolith handling technologies. Hence, in this study, the authors conducted experiments to determine the magnetic permeability that would enable the capture and transport of regolith utilizing the magnetic force. A magnetic capture and transport system that utilizes a coil gun principle was developed for this purpose. In addition, they assessed the feasibility of magnetic capture and transport in the low-gravity and vacuum environment of the lunar surface by numerical simulations using the discrete element method. They predicted that the relative magnetic permeability must be higher than approximately 2.0 for magnetic handling of regolith on Earth. However, the magnetic transport of regolith was possible in the lunar environment, even if the magnetic permeability of the lunar regolith was as low as 1.3.]]></description>
      <pubDate>Tue, 25 Mar 2025 09:32:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2519308</guid>
    </item>
    <item>
      <title>Observer-Based Robust Attitude Control of Liquid-Filled Flexible Spacecraft in a Fully Actuated System Framework</title>
      <link>https://trid.trb.org/View/2519050</link>
      <description><![CDATA[An observer-based robust attitude controller is proposed for a complex spacecraft. The spacecraft consists of a rigid carrier, a flexible appendage, and a partially liquid-filled tank. The appendage is modeled as a Bernoulli-Euler beam, and the liquid sloshing is equivalent to a lumped mechanical multimode model. The spacecraft dynamical equation is derived from the theorem of angular momentum. On the basis of the fully actuated system approach, a second-order attitude system in terms of error quaternions is deduced. To estimate the lumped disturbance consisting of inertial uncertainties, liquid sloshing, appendage vibration, and external disturbances, an extended state observer is constructed. A robust controller is designed based on the fully actuated system approach and the observer. The stability of the controlled system is proved via Lyapunov’s direct method. The present work finds a meaningful discovery that the proposed controller can be free from the unwinding phenomenon, and a brief analysis of the unwinding-free performance is provided based on the stability proof. The simulation results demonstrate the effectiveness of the proposed controller.]]></description>
      <pubDate>Tue, 25 Mar 2025 09:32:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2519050</guid>
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