<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>VTOL UAV Transition Maneuver Using Incremental Nonlinear Dynamic Inversion</title>
      <link>https://trid.trb.org/View/1593347</link>
      <description><![CDATA[The paper seeks to study the control system design of a novel unmanned aerial vehicle (UAV). The UAV is capable of vertical takeoff and landing (VTOL), transition flight and cruising via the technique of direct force control. The incremental nonlinear dynamic inversion (INDI) approach is adopted for the 6-DOF nonlinear and nonaffine control of the UAV. Based on the INDI control law, a method of two-layer cascaded optimal control allocation is proposed to handle the redundant and coupled control variables. For the weight selection in optimal control allocation, a dynamic weight strategy is proposed. This strategy can adjust the weight of the objective function according to the flight states and mission requirements, thus determining the optimizing direction and ensuring the rationality of the allocation results. Simulation results indicate that the UAV can track the target trajectory accurately and exhibit continuous maneuverability in transition flight.]]></description>
      <pubDate>Wed, 24 Apr 2019 09:30:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593347</guid>
    </item>
    <item>
      <title>Research Progresses of Flash Evaporation in Aerospace Applications</title>
      <link>https://trid.trb.org/View/1593346</link>
      <description><![CDATA[Liquid is overheated and evaporated quickly when it enters into the environment with lower saturation pressure than that corresponding to its initial temperature. This phenomenon is known as the flash evaporation. A natural low-pressure environment and flash evaporation have unique characteristics and superiority in high altitude and outer space. Therefore, flash evaporation is widely used in aerospace. In this paper, spray flash evaporation and jet flash evaporation which are two different forms were introduced. Later, key attentions were paid to applications of flash evaporation in aerospace. For example, the flash evaporation has been used in the thermal control system of an aircraft and the propelling system of a microsatellite and oil supply system of a rocket motor. Finally, the latest progresses in the calculation model and numerical simulation of flash evaporation were elaborated.]]></description>
      <pubDate>Wed, 24 Apr 2019 09:30:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593346</guid>
    </item>
    <item>
      <title>Dynamic Behavior and Damage Mechanism of 3D Braided Composite Fan Blade under Bird Impact</title>
      <link>https://trid.trb.org/View/1593340</link>
      <description><![CDATA[The three-dimensional braided composites, with intertwined fiber bundles in the through-thickness direction, have advantages of high interlaminar shear strength, fracture toughness, and excellent impact resistance, making them a promising material for applications in the field of aeroengine fan blades. As the bird impact behavior of the fan blade directly affects the safety of the aeroengines, it is of great significance to study the dynamic response and damage mechanism of 3D braided composites under bird strike load. In this paper, the bird impact tests on the 3D four-step braided composite targets were carried out using the gas gun system. The effects of impact velocity, impact location, and braiding angle on the bird impact behavior were studied. It is concluded that the damage and failure become more severe with the increasing impact velocity. The whole impact event could be divided into 3 stages, i.e., local deformation stage, postflow impact stage, and bending deflection stage. The braided composite presents flexible characteristics and could bear extraordinary deformation during the bird impact. One distinguishing feature of bird impact damage is the destruction of the clamping root due to bending load caused by cantilever construction. The internal damage form at the impact area was mainly the separation of the fiber bundles from the matrix while the breakage of the fiber bundles and the crushing of the matrix play the primary role at the root part. The target plate impacted at the 70% height had the largest bending angle and most serious damage, followed by those impacted at the 90% and 50% heights. Both the appearance damage and internal damage extent are smallest for 45° braiding composites.]]></description>
      <pubDate>Wed, 24 Apr 2019 09:30:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593340</guid>
    </item>
    <item>
      <title>Experimental Study of Spray Characteristics of Kerosene-Ethanol Blends from a Pressure-Swirl Nozzle</title>
      <link>https://trid.trb.org/View/1593343</link>
      <description><![CDATA[Partial replacement of kerosene by ethanol in a gas turbine is regarded as a good way to improve the spray quality and reduce the fossil energy consumption. The present work is aimed at studying the spray characteristics of kerosene-ethanol blends discharging from a pressure-swirl nozzle. The spray cone angle, discharge coefficient, breakup length, and velocity distribution are obtained by particle image velocimetry, while droplet size is acquired by particle/droplet imaging analysis. Kerosene, E10 (10% ethanol, 90% kerosene), E20 (20% ethanol, 80% kerosene), and E30 (30% ethanol, 70% kerosene) have been considered under the injection pressure of 0.1–1 MPa. The results show that as injection pressure is increased, the discharge coefficient and breakup length decrease, while the spray cone angle, drop size, and spray velocity increase. Meanwhile, the drop size decreases and the spray velocity increases with ethanol concentration when the injection pressure is lower than 0.8 MPa. However, the spray characteristics are not affected obviously by the ethanol concentration when the injection pressure exceeds 0.8 MPa. A relation to breakup length for kerosene-ethanol blends is obtained. The findings demonstrate that the adding of ethanol into kerosene can promote atomization performance.]]></description>
      <pubDate>Wed, 24 Apr 2019 09:30:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593343</guid>
    </item>
    <item>
      <title>Effect of Airflow Temperature on the Formation of Initial Flame Kernel and the Propagation Characteristics of Flame</title>
      <link>https://trid.trb.org/View/1593342</link>
      <description><![CDATA[Using liquid RP-3 aviation kerosene as the fuel to study, the effect of airflow temperature on the formation of initial flame kernel during the ignition of spray combustion and on the propagation characteristics of flame was investigated. Combining high-speed camera and dynamic temperature acquisitions at the outlet of combustor, the internal triggering mode was used under a constant fuel flow rate and airflow velocity. This combined system simultaneously recorded the formation of initial flame kernel, flame propagation, and outlet temperature variation of combustor under different airflow temperatures. MATLAB software was used to obtain the reaction zones at different moments and to analyze the effects of airflow temperature on morphological characteristics such as flame area, perimeter-to-area ratio, maximum length-to-height ratio, equivalent mean length-to-height ratio, mass center, and centroid. According to the growth rate in flame area, the ignition process can be divided into three stages: formation of flame kernel, rapid development of flame, and stable development of flame. Airflow temperature not only affects the formation time of flame kernel but also affects the growth rate of flame area. During the development of flame, the movements of mass center and centroid are irregular, and their positions do not coincide with each other. However, the overall moving trends are consistent. With the increase of the airflow temperature, the position, where the flame kernel is gradually formed, moves closer to the center of the end face of spark plug. The force of airflow on flame is the main factor that increases the flame area and heat-release rate. Therefore, the folds around the flame edge mainly result from the stretching under the action of airflow. With the increase in airflow temperature, the heat release of the initial flame kernel increases, and the ratio of perimeter to area as a characterization parameter increases by 8%, 86%, and 33%, respectively. In addition, the maximum outlet temperature rise increased by about 53%, 73.5%, and 0.65%, respectively. Meanwhile, the maximum rate of temperature rise increased by about 42.8%, 57%, and 5.1%, respectively.]]></description>
      <pubDate>Wed, 24 Apr 2019 09:30:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593342</guid>
    </item>
    <item>
      <title>Dynamical Model Identification for a Small-Scale Unmanned Helicopter Using an Integrated Approach</title>
      <link>https://trid.trb.org/View/1593341</link>
      <description><![CDATA[This article presents an integrated approach for the parameter identification of a small-scale unmanned helicopter. With the flight experiment data collection and preprocessing, a hybrid identified algorithm combining the improved artificial bee colony algorithm and prediction error method is proposed to obtain the unknown dynamical parameters of the linear model. The proposed algorithm is valid to use thanks to an adaptive search equation, a novel probability-scaling method, and a chaotic operator and has a good performance in search speed and quality. Afterwards, the authors design a wind tunnel test to modify the main rotor time constant of the identified model. The identified accuracy and feasibility of the proposed approach are verified by making a time-domain comparison with three other algorithms. Results show that the dynamical characteristics of the helicopter can be determined accurately by the identified model. And the proposed approach is propitious to enhance the reliability and availability of the identified dynamical model.]]></description>
      <pubDate>Wed, 24 Apr 2019 09:30:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593341</guid>
    </item>
    <item>
      <title>Research on Simulation and Performance Optimization of Mach 4 Civil Aircraft Propulsion Concept</title>
      <link>https://trid.trb.org/View/1593345</link>
      <description><![CDATA[Supersonic civil aircraft is of a promising area in the development of future civil transport, and aircraft propulsion system is one of the key issues which determine the success of the aircraft. To get a good conceptual design and performance investigation of the supersonic civil aircraft engine, in this article, a fast, versatile as well as trust-worthy numerical simulation platform was established to analyze the Mach 4 turbine-based combined cycle (TBCC) engine concept so as to be applied to the supersonic civil aircraft. First, a quick and accurate task requirement analysis module was newly established to analyze the mission requirement of the Mach 4 supersonic civil aircraft. Second, the TBCC engine performance simulation model was briefly presented and the number of engines on the supersonic civil aircraft was analyzed, considering single engine inoperative. Third, the Stone model and the DLR method were investigated to estimate the engine jet noise and the NOx emission of the Mach 4 supersonic civil aircraft. Finally, a multiobjective optimization tool made up of a response surface method and a genetic algorithm was developed to optimize the design parameters and the control law of the TBCC engine, in order to make the Mach 4 supersonic civil aircraft engine with better performance, lower noise, and lower emissions. The uniqueness of the developed analysis tool lies in that it affords a numerical simulation platform capable of investigating the task requirement analysis module of the supersonic civil aircraft, engine jet noise prediction model, and the NOx emission prediction model, as well as a multiobjective performance optimization tool, which is beneficial for the conceptual design and performance research of Mach 4 supersonic civil aircraft’s propulsion system.]]></description>
      <pubDate>Wed, 24 Apr 2019 09:30:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593345</guid>
    </item>
    <item>
      <title>Guaranteeing Prescribed Performance Control for Gyrostabilized Platform with Unknown Control Direction Preceded by Hysteresis</title>
      <link>https://trid.trb.org/View/1593344</link>
      <description><![CDATA[This paper investigates the problem of precise and quick tracking for gyrostabilized platform (GSP) with unknown hysteresis, unknown control directions, and unknown compound disturbance. Firstly, the dynamic model of GSP is transformed into a strict feedback formulation by designed FD to facilitate the backstepping control system. Secondly, performance functions are constructed at each step of backstepping design to force tracking errors to fall within the prescribed boundaries. Besides, through ingenious transformation, radial basis function neural network (RBFNN) is applied to estimate the unknown control gains preceded by hysteresis. Hence, the problem of prescribed performance control with unknown compound disturbances, unknown hysteresis, and unknown control directions is creatively solved. Furthermore, the exploited controllers are accurate model independent, which guarantees satisfactory robustness of control laws against unknown uncertainties. Finally, the stability of the closed-loop control system is confirmed via Lyapunov stability theory, and numerical simulations are given for a GSP to validate the effectiveness of the proposed controller.]]></description>
      <pubDate>Wed, 24 Apr 2019 09:30:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593344</guid>
    </item>
    <item>
      <title>Design of a Three-Dimensional Hypersonic Inward-Turning Inlet with Tri-Ducts for Combined Cycle Engines</title>
      <link>https://trid.trb.org/View/1593339</link>
      <description><![CDATA[The operation of a propulsion system in terms of horizontal takeoff/landing and full-speed range serves as one of the main difficulties for hypersonic travelling. In the present work, a three-dimensional inward-turning inlet with tri-ducts for combined cycle engines is designed for the operation of three different modes controlled by a single rotational flap on the compression side, which efficiently simplifies the inlet structure and the flap control mechanism. At high flight speed between Mach 4 and 6, the pure scramjet mode is switched on, whereas both the ejector and the scramjet paths are open for a moderate Mach number between 2 and 4 with a larger throat area guaranteeing the inlet startability. In the low flight speed range with Mach number below 2, the additional turbojet path will be turned on to supply air for the turbine engine, whereas the other two paths remain open for spillage. Numerical simulations under different operation modes have proven the feasibility and good performance of the designed inlet, e.g., a nearly full mass flow ratio and a total pressure recovery around 0.5 can be achieved at the cruise speed. Meanwhile, the inlet works properly at low flight speeds which overcomes the typical starting problem of similar inlet designs. In the near future, wind tunnel experiments will be carried out to validate the authors' inlet design and its performance.]]></description>
      <pubDate>Fri, 22 Mar 2019 16:15:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593339</guid>
    </item>
    <item>
      <title>Design and Simulation of Eight-Rotor Unmanned Aerial Vehicle Based on Hybrid Control System</title>
      <link>https://trid.trb.org/View/1593338</link>
      <description><![CDATA[In order to control the position and attitude of unmanned aerial vehicle (UAV) better in different environments, this study proposed a hybrid control system with backstepping and PID method for eight-rotor UAV in different flight conditions and designed a switching method based on altitude and attitude angle of UAV. The switched process of hybrid controller while UAV taking off, landing, and disturbance under the gust is verified in MATLAB/Simulink. A set of appropriate controllers always matches to the flight of UAV in different circumstances, which can speed up the system response and reduce the steady-state error to improve stability. The simulation results show that the hybrid control system can suppress the drift efficiently under gusts, enhance the dynamic performance and stability of the system, and meet the position and attitude of flight control requirements.]]></description>
      <pubDate>Fri, 22 Mar 2019 16:15:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593338</guid>
    </item>
    <item>
      <title>Characterization of Flow Interactions in a One-Stage Shrouded Axial Turbine</title>
      <link>https://trid.trb.org/View/1593337</link>
      <description><![CDATA[The aim of this paper is to characterize the steady and unsteady flow interactions through a one-stage high-pressure (hp) shrouded axial turbine with a tip cavity. The vane and blade passages were reduced based on the scaling technique, and the domains of compromise were identified and used in the flow computations. The flow structures are mainly in the form of vanes’ wakes and vortices inducing circumferential distortions and interacting with the rotor blades. Fast Fourier transform (FFT) of the static pressure fluctuations recorded at the selected points and lines through the turbine stage revealed high unsteadiness characterized by a space-time periodic behavior, and described by the double Fourier decomposition. The vane-rotor interactions (VRI) appeared in the form of a potential flow field about the blades extending both upstream and downstream and correlated with the rotational speed. The other sources of unsteadiness are induced in the rotor blades by the vanes’ wakes and referred to as the wake interaction, in addition to the secondary flows and vortices in endwall regions.]]></description>
      <pubDate>Fri, 22 Mar 2019 16:15:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593337</guid>
    </item>
    <item>
      <title>Air Data Sensor Fault Detection with an Augmented Floating Limiter</title>
      <link>https://trid.trb.org/View/1593336</link>
      <description><![CDATA[Although very uncommon, the sequential failures of all aircraft Pitot tubes, with the consequent loss of signals for all the dynamic parameters from the Air Data System, have been found to be the cause of a number of catastrophic accidents in aviation history. This paper proposes a robust data-driven method to detect faulty measurements of aircraft airspeed, angle of attack, and angle of sideslip. This approach first consists in the appropriate selection of suitable sets of model regressors to be used as inputs of neural network-based estimators to be used online for failure detection. The setup of the proposed fault detection method is based on the statistical analysis of the residual signals in fault-free conditions, which, in turn, allows the tuning of a pair of floating limiter detectors that act as time-varying fault detection thresholds with the objective of reducing both the false alarm rate and the detection delay. The proposed approach has been validated using real flight data by injecting artificial ramp and hard failures on the above sensors. The results confirm the capabilities of the proposed scheme showing accurate detection with a desirable low level of false alarm when compared with an equivalent scheme with conventional “a priori set” fixed detection thresholds. The achieved performance improvement consists mainly in a substantial reduction of the detection time while keeping desirable low false alarm rates.]]></description>
      <pubDate>Fri, 22 Mar 2019 16:15:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1593336</guid>
    </item>
    <item>
      <title>An Efficient Contact Model for the Simulation of Cargo Airdrop Extraction Phase</title>
      <link>https://trid.trb.org/View/1566553</link>
      <description><![CDATA[A high-fidelity cargo airdrop simulation requires the accurate modeling of the contact dynamics between an aircraft and its cargo. This paper presents a general and efficient contact-friction model for the simulation of aircraft-cargo coupling dynamics during an airdrop extraction phase. The proposed approach has the same essence as the finite element node-to-segment contact formulation, which leads to a flexible, straightforward, and efficient code implementation. The formulation is developed under an arbitrary moving frame with both aircraft and cargo treated as general six degrees-of-freedom rigid bodies, thus eliminating the restrictions of lateral symmetric assumptions in most existing methods. Moreover, the aircraft-cargo coupling algorithm is discussed in detail, and some practical implementation details are presented. The accuracy and capability of the present method are demonstrated through four numerical examples with increasing complexity and fidelity.]]></description>
      <pubDate>Tue, 20 Nov 2018 10:17:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1566553</guid>
    </item>
    <item>
      <title>CFD Analysis of Contrarotating Open Rotor Aerodynamic Interactions</title>
      <link>https://trid.trb.org/View/1566552</link>
      <description><![CDATA[High efficiency and low fuel consumption make the contrarotating open rotor (CROR) system a viable economic and environmentally friendly powerplant for future aircraft. While the potential benefits are well accepted, concerns still exist with respect to the vibrations and noise caused by the aerodynamic interactions of CROR systems. In this paper, emphasis is placed on the detailed analysis of the aerodynamic interactions between the front and aft propellers of a puller CROR configuration. For the first step, unsteady Reynolds-averaged Navier-Stokes (URANS) simulations coupled with dynamic patched grid technology are implemented on the isolated single-rotating propeller (SRP) configuration in various operating conditions in order to test the accuracy and feasibility of the numerical approach. The numerical results are verified by a wind tunnel test, showing good agreements with the experimental data. Subsequently, the URANS approach is applied to the CROR configuration. The numerical results obtained through the URANS approach help to improve the understanding of the complex flow field generated by the CROR configuration, and the comparison of SRP flow field and CROR flow field allows for a detailed analysis of the aerodynamic interactions of the front propeller blade wakes and tip vortices with the aft propeller. The main reason of the aerodynamic interactions is the mutual effects of the blade tip vortices, and the aft propeller reduces the strength of the blade tip vortices of the front propeller. Aerodynamic interactions will lead to the periodic oscillations of the aerodynamic forces, and the frequency of the oscillations is linked to the blade numbers. In addition, a CROR has a larger thrust and power coefficient than that of the SRP configuration in the same operating conditions. The URANS approach coupled with a dynamic patched grid method is tested to be an efficient and accurate tool in the analysis of propeller aerodynamic interactions.]]></description>
      <pubDate>Tue, 20 Nov 2018 10:17:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1566552</guid>
    </item>
    <item>
      <title>Can Scalable Design of Wings for Flapping Wing Micro Air Vehicle Be Inspired by Natural Flyers?</title>
      <link>https://trid.trb.org/View/1566551</link>
      <description><![CDATA[Lift production is constantly a great challenge for flapping wing micro air vehicles (MAVs). Designing a workable wing, therefore, plays an essential role. Dimensional analysis is an effective and valuable tool in studying the biomechanics of flyers. In this paper, geometric similarity study is firstly presented. Then, the  Pw –AR ratio is defined and employed in wing performance estimation before the lumped parameter is induced and utilized in wing design. Comprehensive scaling laws on relation of wing performances for natural flyers are next investigated and developed via statistical analysis before being utilized to examine the wing design. Through geometric similarity study and statistical analysis, the results show that the aspect ratio and lumped parameter are independent on mass, and the lumped parameter is inversely proportional to the aspect ratio. The lumped parameters and aspect ratio of flapping wing MAVs correspond to the range of wing performances of natural flyers. Also, the wing performances of existing flapping wing MAVs are examined and follow the scaling laws. Last, the manufactured wings of the flapping wing MAVs are summarized. The authors' results will, therefore, provide a simple but powerful guideline for biologists and engineers who study the morphology of natural flyers and design flapping wing MAVs.]]></description>
      <pubDate>Tue, 20 Nov 2018 10:17:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1566551</guid>
    </item>
  </channel>
</rss>