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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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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>A Novel DVL Aided Inertial Navigation Strategy for Long-Endurance Robust Positioning of AUVs</title>
      <link>https://trid.trb.org/View/2591912</link>
      <description><![CDATA[Stable and reliable high-precision navigation and positioning is regarded as an urgent demand for marine intelligent transportation system. Medium and large autonomous underwater vehicles (AUVs) can be equipped with various navigation sensors to ensure positioning accuracy. In contrast, small AUVs have limited carrying capacity, and how to achieve reliable positioning for long endurance with more basic and necessary sensors is worthy of in-depth investigation. Therefore, a robust Doppler velocity log (DVL) aided inertial navigation strategy is designed in this survey. A tightly integrated system model based on DVL Doppler shift and ranging information aided inertial navigation system is established, which solves the problem of positioning performance degradation caused by error accumulation and beam failure in traditional methods. Based on consistency principle of sensor equipment, the system residual is identified by dead reckoning model and compensated for DVL terrain aided navigation, which solves the problem that systematic errors have great influence on nonlinear terrain and are difficult to identify. At the same time, the terrain entropy is introduced to design the confidence evaluation algorithm, which improves the adaptability of system in different terrain scenes. Simulation and lake test results show that the proposed method has higher positioning accuracy, reliability and stability, and is suitable for AUVs long-endurance navigation tasks.]]></description>
      <pubDate>Wed, 12 Nov 2025 09:36:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2591912</guid>
    </item>
    <item>
      <title>Machine Learning Methods for Track Condition Assessment Using Repeated Inspection Data</title>
      <link>https://trid.trb.org/View/2447213</link>
      <description><![CDATA[The Railway Technologies Laboratory (RTL) at Virginia Tech has significantly advanced the science of using Doppler velocimetry methods to evaluate track stability. This report provides an overview of the progress made during the project. The project was split into two primary tasks. Task 1 concentrates on analyzing existing data from past field testing of a Multifunction Doppler LIDAR system. Task 2 focused on preparing and making the necessary improvements to the LIDAR instruments for future track testing. It was determined that designing and assembling a new set of digital platforms (i.e., special-purpose computers) would be important for the long-term success of testing the Multifunction Doppler LIDAR in track testing. During this study, two new digital platforms were assembled in addition to a second LIDAR Electro-optical unit. Further, new focusing lenses were assembled and the output laser power was increased to maximize the signal-to-noise ratio (SNR) of the LIDAR instrument. These electro-optical upgrades are expected to yield an SNR improvement of up to four times the previous units. Bench top system tests were performed with the new LIDAR instrumentation and the new instruments are now ready for field testing.]]></description>
      <pubDate>Wed, 20 Nov 2024 13:08:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2447213</guid>
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    <item>
      <title>Experimental assessment of the rotor outlet flow in a twin-entry radial turbine by means of Laser Doppler Anemometry</title>
      <link>https://trid.trb.org/View/2026895</link>
      <description><![CDATA[The current paper presents the validation of some hypotheses used for developing a one-dimensional twin-entry turbine model with experimental measurements. A Laser Doppler Anemometry (LDA) technique has been used for measuring the axial Mach number and for counting the number of particles downstream of the rotor outlet. These measurements have been done for different mass flow ratio (MFR) and reduced turbocharger speed conditions. The flow coming from each turbine entry does not fully mix with the other within the rotor since, downstream of the rotor, they can still be differentiated. Thus, the hypothesis of studying twin-entry turbines as two separated single-entry turbines in one-dimensional models is corroborated. Moreover, the rotor outlet area corresponding to each flow branch has linear trends with the MFR value. Therefore, the rotor outlet effective area used for one-dimensional models should vary linearly with the MFR value.]]></description>
      <pubDate>Mon, 28 Nov 2022 10:56:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2026895</guid>
    </item>
    <item>
      <title>Analysis of the Correlation between Flow and Combustion Characteristics in Spark-Ignited Engine</title>
      <link>https://trid.trb.org/View/1847713</link>
      <description><![CDATA[As global emission standards are becoming more stringent, it is necessary to increase thermal efficiency through the high compression ratio in spark-ignited engines. Various studies are being conducted to mitigate knocking caused by an increased compression ratio, which requires an understanding of the combustion phenomena inside the combustion chamber. In particular, the in-cylinder flow is a major factor affecting the entire combustion process from the generation to the propagation of flames. In the field of spark-ignited engine research, where interest in the concept of lean combustion and the expansion of the EGR supply is increasing, flow analysis is essential to ensure a rapid flame propagation speed and stable combustion process. In this study, the flow around the spark plug was measured by the Laser Doppler Velocimetry system, and the correlation with combustion in spark-ignited engines was analyzed. The turbulence intensity at the spark plug was calculated by measuring the flow velocity by using a probe adaptor installed in place of the spark plugs under motoring conditions. To measure the flow characteristics of various engine conditions, LDV measurement experiments were conducted with different engine speeds, intake pressures and valve timings. In addition, the design of the intake port was changed to analyze the flow characteristics according to the tumble ratio. Compared to other engine variables, the engine speed and intake valve timing have greater influence on the flow around the spark plug. In engines with different tumble ratios, the profile of the flow velocity is different. To identify the relationship between the flow characteristics and the combustion process, combustion under various conditions was compared to the flow measured with the LDV system in the same engines. Under part load conditions, there was a lack of correlation between the turbulence velocity near the spark plug and the burn duration, however, the initial flame propagation speed showed a high correlation.]]></description>
      <pubDate>Tue, 26 Oct 2021 14:30:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1847713</guid>
    </item>
    <item>
      <title>Network and Project Level Structural Evaluation Using the Traffic Speed Deflectometer</title>
      <link>https://trid.trb.org/View/1743828</link>
      <description><![CDATA[Pavement structural condition is one of the main factors which affect the development of pavement distress such as rutting and fatigue cracking. Knowledge about the structural condition allows for prediction of pavement distress, and is of fundamental importance to intelligent asset management. Acquiring structural condition data has historically been expensive and time-consuming, relying on discrete point measurements from slow moving Falling Weight Deflectometers (FWD). The Traffic Speed Deflectometer (TSD) offers an alternate approach to measuring structural condition, which avoids most of the issues associated with FWD measurements. Using an innovative principle based on Doppler lasers, the Traffic Speed Deflectometer measures the pavement response to a 10 ton axle while driving at normal traffic speed (1 km/h – 90 km/h). As the quality of TSD measurements has improved over the years, the range of applications has widened as well. Whereas the early TSD versions were mainly used as a scanning tool, the newest TSDs deliver data of a quality suitable for back-calculation and work at the project level. Also, the recent addition of sensors behind the load axle makes it possible to probe the full asymmetric deflection basin and assess the role of visco-elasticity. To take full advantage of these improvements, a TSD-specific back-calculation algorithm was recently developed. The algorithm is based on a linear visco-elastic pavement model and takes the driving speed of the vehicle into account. As part of the back-calculation, the complex viscoelastic moduli of the pavement layers are found. The visco-elastic moduli are a detailed quantitative measure of the structural condition, and allow for prediction of future pavement distress. In this paper, the developed back-calculation algorithm is applied to real TSD data, and it is discussed how the results can be used to evaluate and predict performance.]]></description>
      <pubDate>Wed, 03 Feb 2021 15:00:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/1743828</guid>
    </item>
    <item>
      <title>Acoustic Measurement of Ship Wave–Induced Sediment Resuspension in a Large River</title>
      <link>https://trid.trb.org/View/1762430</link>
      <description><![CDATA[This paper presents a proof of concept that acoustic velocity and backscatter intensity measurements can provide essential information on ship wave–induced sediment transport processes in the littoral zone of a large river. Through a case study in the Hungarian section of Danube River, a combined application of an acoustic Doppler velocimeter (ADV) and a formerly calibrated acoustic backscatter sensor (ABS) is introduced for parallel measurements of 3D flow velocities and suspended sediment concentration (SSC) in a characteristic point of the near-bank zone. SSC times series detected by the ABS supported the calibration of the ADV backscatter, which eventually enabled the analysis of the temporal behavior of flow velocity and SSC conditions altered by ship waves. A suitable method for the separation of primary and secondary waves provided essential information on the turbulence intensities and sediment fluxes, and was found that the low-frequency primary waves are rather responsible for the lateral sediment transport instead of the dynamic secondary waves. The introduced data processing techniques and the main findings of the paper mean an important step toward the better understanding of the impacts of ship waves on the riverbanks, inherently playing a crucial role in the hydro-morphological and habitat conditions of river systems.]]></description>
      <pubDate>Tue, 26 Jan 2021 09:37:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/1762430</guid>
    </item>
    <item>
      <title>LDV Wake Vortex Detection System Assessment</title>
      <link>https://trid.trb.org/View/1570055</link>
      <description><![CDATA[This report summarizes the methodology and findings of an engineering evaluation of the Laser Doppler Velocimeter (LDV). The LDV is owned and operated by the Department of Transportation, and is used as a research tool in the aircraft Wake Vortex program. The purpose of this effort is to perform an independent technical review of the capability of the LDV to provide quantitative data concerning the location, velocity, size and strength of aircraft wake vortices. The LDV was evaluated from two perspectives: (1) Basic hardware/signal processing capabilities and limitations and (2) Post-test data processing procedures. To understand the basic hardware/signal processing characteristics of the system, an analytic LDV simulation was developed and exercised. This simulation captures the major sensor characteristics and its operation, and provides an understanding of what the LDV data collection limitations are. Frequent discussions and meetings were held with the Volpe National Transportation Systems Center (VNTSC) staff as part of the review and evaluation of post-test data processing procedures currently applied to the LDV data. LDV, tower anemometer, and other meteorological data were analyzed by TASC (The Analytic Sciences Corporation) in order to compare LDV and tower measurement capabilities, to identify and explain discrepancies, and to make recommendations for modifications to the LDV post-test data processing procedures. Several modifications that have the potential to improve the quality of information extracted from the LDV were identified.]]></description>
      <pubDate>Wed, 05 Dec 2018 16:27:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1570055</guid>
    </item>
    <item>
      <title>In-Cylinder Flow Optimization Process for Thermal Efficiency Improvement of Gasoline Engine</title>
      <link>https://trid.trb.org/View/1549716</link>
      <description><![CDATA[An enhancement of a tumble flow is one of the effective methods to improve lean and diluted combustion stability limits in SI engines. In this study, an evaluation method of the tumble flow quality by means of multipoint LDV is proposed. Effects of a tumble flow quality to turbulent characteristics and flame propagations are also investigated. Tumble ratio, turbulent intensity, effective opening areas and tumble qualities which are defined as standardized targets of phenomena to develop in-cylinder flow of SI engine. It is shown that the standardized flow characteristics targets make possible to improve the thermal efficiency and stabilities of lean and diluted combustion limits.水平対向直噴エンジンにおける燃焼開発について報告する．可視化計測や単気筒エンジンを活用して，更なるガス流動改善を行い，ストイキ高EGR環境下での燃焼耐力向上とそれに伴う燃費向上を実現した．その考え方や具体的方法を紹介する．]]></description>
      <pubDate>Fri, 26 Oct 2018 10:36:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/1549716</guid>
    </item>
    <item>
      <title>Measurement of Fuel Injection Rate by LDA Flow Rate Meter and Spray Characteristics</title>
      <link>https://trid.trb.org/View/1499942</link>
      <description><![CDATA[It is necessary to clarify spray characteristics for improvement combustion efficiency. The authors' group has been developed LDA flow rate meter based on Laser Doppler Anemometer (LDA) for the fuel injection rate measurement. The paper introduces the study of a flow rate measurement by LDA flow meter, Bosch type injection rate meter and of a visualization by high-speed camera. The fuel injection rate is measured with various fuel pressures and injection durations. It is clarified that the reflection pressure wave measured LDA flow rate meter does not affect spray characteristics.内燃機関の燃焼効率向上には燃料の噴霧性状の解明が重要である．噴霧性状を解明するため高速度カメラによる可視化とBosch 式噴射率計を用いた噴射率の計測を行った．さらにLDA 流量計を用いてインジェクタ上流部での管内流量を計測した．その結果，インジェクタ上流部での流量変化による噴霧性状への影響を明らかにした．]]></description>
      <pubDate>Mon, 23 Apr 2018 16:47:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/1499942</guid>
    </item>
    <item>
      <title>LDV Measurements of B-747 Wake Vortex Characteristics</title>
      <link>https://trid.trb.org/View/1469452</link>
      <description><![CDATA[In order to determine the behavior of the wake vortices of a B-747 at low altitudes and to measure the vortex decay process behind the B-747 as a function of altitude above ground, flap and spoiler settings and different flight configurations; a B-747 aircraft flew 54 passes at low level over a ground-based laser Doppler velocimeter (LDV) system and other sensors. From the LDV measurements, the location and velocity distribution of the wake vortices and the general vortex roll-up, transport and decay trends were obtained. Results of the study indicated that the deployment of spoilers and flaps enhanced the decay of the vortex peak tangential velocity in the near wake while aircraft altitude glide slope, and landing gear deployment has little effect. The report discusses the LDV wake vortex measurements including the instrumentation used, the experimental test sequence, and the results of the wake measurements in terms of the vortex roll-up, transport and decay trends, and a comparison of the wake vortex characteristics for different configurations.]]></description>
      <pubDate>Thu, 15 Jun 2017 13:19:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/1469452</guid>
    </item>
    <item>
      <title>Investigation of Sediment Suspension Technology</title>
      <link>https://trid.trb.org/View/1467195</link>
      <description><![CDATA[The goal of the project was to critically review existing literature to access currently available devices, the identification of areas of improvement for future designs, and the outline of a new-generation cohesive sediment erosion measuring device. The results of this investigation shows that several devices exist for the measurement of cohesive sediment erosion upon which there are great opportunities for improvement. Most significantly, the availability of technologies such as laser Doppler velocimeters (LDV) and bed mapping systems would allow for the noninvasive measurement of key parameters directly in the field. The introduction of such instruments to the framework of existing flume devices would allow for greater accuracy in determining a relationship between bed shear stress and suspended sediment concentration. Direct measurement of the flow profile by the LDV would erase the potential for error where flows were previously estimated. Acoustic bed mapping technology has already been successfully utilized in the NIWA-II flume to noninvasively measure the erosion process (Aberle et al. 2004, Debnath et al. 2007). However, the integration of more advanced technologies, whether laserbased or acoustic, has the potential to improve accuracy and resolution in measurements. The development of the proposed device is realistic and achievable, and would enhance the understanding of cohesive sediment erosion.]]></description>
      <pubDate>Wed, 31 May 2017 09:31:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1467195</guid>
    </item>
    <item>
      <title>WIND TUNNEL EVALUATION OF FLOW FIELDS WITHIN STREET CANYONS WITH THERMAL STRATIFICATION : Experimental studies on gaseous diffusion in urban areas Part 4</title>
      <link>https://trid.trb.org/View/1450823</link>
      <description><![CDATA[Results of wind tunnel experiments on the influences of road width and thermal stratification on air flow in urban street canyons are presented. 1) A typical characteristic of the flow in street canyons is the formation of a strong cavity eddy when the road width L is equal to one to two times the height of the adjacent buildings. H. 2) The cavity eddy weakens as length/height (L/H) is increased from 2 to 4 and decays with further increases in road width under neutral conditions. 3) Although the cavity eddy strengthens under unstably stratified conditions within the skimming flow regime, cavity eddy decay occurs earlier in wake interference flow regimes and the transition to isolated roughness flow regimes begins earlier than under neutral conditions. 4) Thermal stratification has a greater impact on turbulence than does road width.]]></description>
      <pubDate>Fri, 31 Mar 2017 17:09:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1450823</guid>
    </item>
    <item>
      <title>An Experimental Study of Gaseous Transverse Injection and Mixing Process in a Simulated Engine Intake Port</title>
      <link>https://trid.trb.org/View/1432897</link>
      <description><![CDATA[The flow field resulting from injecting a gas jet into a crossflow confined in a narrow square duct has been studied under steady regime using schlieren imaging and laser Doppler velocimetry (LDV). This transparent duct is intended to simulate the intake port of an internal combustion engine fueled by gaseous mixture, and the jet is issued from a round nozzle. The schlieren images show that the relative small size of the duct would confine the development of the transverse jet, and the interaction among jet and sidewalls strongly influences the mixing process between jet and crossflow. The mean velocity and turbulence fields have been studied in detail through LDV measurements, at both center plane and several cross sections. The well-known flow feature formed by a counter rotating vortex pair (CVP) has been observed, which starts to appear at the jet exit section and persists far downstream contributing to enhancing mixing process.In addition, jets of different gases have been investigated with various injection orientations, aiming to fully understand the behaviors of transverse jet and the mixing process in the simulated intake port under wide practical conditions. Particularly, jet injection against crossflow has been found favorable in this study. The results show that the injection direction can influence the flow field remarkably, while the effect of injected gas is negligible, when the appropriate scaling is applied. A detailed description of the flow field inside a model intake port of an engine fueled with gaseous fuel is provided by the presented study and can be the basis for future comparison with computations.]]></description>
      <pubDate>Thu, 05 Jan 2017 16:24:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1432897</guid>
    </item>
    <item>
      <title>Experimental Study of the Flow Induced by a Vehicle Fan and the Effect of Engine Blockage in a Simplified Model</title>
      <link>https://trid.trb.org/View/1410225</link>
      <description><![CDATA[Fans are often tested without downstream blockage and, thus, the performance is considerably different when the fan is mounted in a vehicle as part of a cooling system and where high blockage effect is present downstream. The aim of the present work is to analyze by laser Doppler velocimetry LDV measurements the topology of the flow induced by a fan incorporated in a simplified underhood model reproducing engine blockage and to study the blockage effect of the engine positioning on the flow induced by the fan. The distance between the fan and the engine block affects the mean flow axial velocity U. The vertical velocity component W is greatly influenced by the variation of the distance between the fan and the engine block, both in magnitude and topology.]]></description>
      <pubDate>Tue, 28 Jun 2016 16:22:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1410225</guid>
    </item>
    <item>
      <title>Flapping Instability of Vertically Impinging Turbulent Plane Jets in Shallow Water</title>
      <link>https://trid.trb.org/View/1394848</link>
      <description><![CDATA[A submerged, vertical, turbulent plane jet impinging onto a free water surface will be self-excited into a flapping oscillation when the jet velocity, exiting the jet orifice, exceeds a critical value. The dependence of the critical velocity W₀c and the flapping frequency f₀ on the water depth H and the jet orifice width d was investigated in detail in this study. The jet flapping motion was visualized by a laser induced fluorescence technique and measured with a laser Doppler velocimeter; a supplemental measurement of the displacement of water surface by a surface wave gauge was made. The jet flapping characteristics are interpreted in terms of the effective water depth given by He = H-z₀, where z₀ is the virtual origin of the jet. The critical jet exit velocity was found to increase linearly with the effective water depth and to decrease with the square root of the jet orifice width. The flapping frequency decreased with the root square of the effective water depth and independent of the jet orifice width. These results led to a critical condition for the onset of instability as St = 0.929[(H − z₀)/d]⁻³/², where St is the critical Strouhal number defined by St = f₀d/W₀c.]]></description>
      <pubDate>Thu, 28 Jan 2016 09:01:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/1394848</guid>
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