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    <title>Transport Research International Documentation (TRID)</title>
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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>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Beyond conventional vision: RGB-event fusion for robust object detection in dynamic traffic scenarios</title>
      <link>https://trid.trb.org/View/2590616</link>
      <description><![CDATA[The dynamic range limitation is intrinsic to conventional RGB cameras, which reduces global contrast and causes the loss of high-frequency details such as textures and edges in complex, dynamic traffic environments (e.g., nighttime driving or tunnel scenes). This deficiency hinders the extraction of discriminative features and degrades the performance of frame-based traffic object detection. To address this problem, the authors introduce a bio-inspired event camera integrated with an RGB camera to complement high dynamic range information, and propose a motion cue fusion network (MCFNet), an innovative fusion network that optimally achieves spatiotemporal alignment and develops an adaptive strategy for cross-modal feature fusion, to overcome performance degradation under challenging lighting conditions. Specifically, the authors design an event correction module (ECM) that temporally aligns asynchronous event streams with their corresponding image frames through optical-flow-based warping. The ECM is jointly optimized with the downstream object detection network to learn task-ware event representations. Subsequently, the event dynamic upsampling module (EDUM) enhances the spatial resolution of event frames to align its distribution with the structures of image pixels, achieving precise spatiotemporal alignment. Finally, the cross-modal mamba fusion module (CMM) employs adaptive feature fusion through a novel cross-modal interlaced scanning mechanism, effectively integrating complementary information for robust detection performance. Experiments conducted on the DSEC-Det and PKU-DAVIS-SOD datasets demonstrate that MCFNet significantly outperforms existing methods in various poor lighting and fast moving traffic scenarios. Notably, on the DSEC-Det dataset, MCFNet achieves a remarkable improvement, surpassing the best existing methods by 7.4% in mAP50 and 1.7% in mAP metrics, respectively.]]></description>
      <pubDate>Fri, 24 Oct 2025 16:53:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2590616</guid>
    </item>
    <item>
      <title>Detecting Non-Recurrent Congestion in Urban Networks: A Comparative Analysis of Advanced Computational Models and Traffic Pattern Visualization</title>
      <link>https://trid.trb.org/View/2475592</link>
      <description><![CDATA[Traffic congestion, especially non-recurrent congestion (NRC), severely impacts urban mobility and safety. To address this, it is crucial to swiftly identify NRC events, leading to optimized traffic management and fewer disruptions. Utilizing the Hong Kong government’s strategic route data, such as speed, flow, and occupancy parameters, this study seeks to pinpoint and assess NRC instances. The authors employed a range of computational methods: One-Class Support Vector Machines (One-SVM), recurrent neural networks (RNN), heuristic algorithms, and the Isolation Forest. To validate these models, predictions were compared with official accident records, providing insight into their accuracy in detecting non-recurrent congestion. Additionally, visual representations of congestion data further enriched the assessment. The analysis reveals the Isolation Forest model’s superior performance in identifying NRC, validated through experiments with accident data. This emphasizes the crucial role of advanced analytics in enhancing urban transport intelligence and safety.]]></description>
      <pubDate>Mon, 23 Dec 2024 10:37:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/2475592</guid>
    </item>
    <item>
      <title>Interactive GIS Map-Based Decision Support Program on Multiyear Pavement Needs Analysis</title>
      <link>https://trid.trb.org/View/2187693</link>
      <description><![CDATA[This paper presents the methodology and application of an interactive GIS map-based decision support program developed for Georgia Department of Transportation's multiyear pavement needs analysis system. The program integrates GIS capabilities, including visualization, identification, and spatial analysis, with multiyear pavement performance forecasting, treatment determination, and pavement preservation needs analysis. It allows engineers not only to visualize spatial and temporal pavement needs analysis results on a GIS map, but also to perform various what-if scenario analyses directly on the GIS maps. Thus, engineers can easily incorporate additional data and make effective decisions. A case study using the actual historical pavement condition data surveyed by the Georgia Department of Transportation is presented to illustrate the capabilities of the developed program.]]></description>
      <pubDate>Wed, 18 Dec 2024 10:56:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/2187693</guid>
    </item>
    <item>
      <title>Investigation on the lean-combustion characteristics of non-uniform orifice pre-chamber spark plug in low engine speed working conditions compared with high energy spark ignition</title>
      <link>https://trid.trb.org/View/2444838</link>
      <description><![CDATA[For a long time, pre-chamber jet ignition has been an effective method to achieve stable lean-combustion of the engine. However, due to the lack of an additional fuel injector, the passive pre-chamber easily leads to unstable combustion and even misfires during the engine’s low-speed working conditions. This study used simulation and optical single-cylinder engine visualization experiments to investigate the ignition and combustion performance of the pre-chamber spark plug (PCSP) ignition system and different orientations of the scavenging jet nozzle in the cylinder. The results indicate that the PCSP at low speed (1200 r/min) can improve the lean-combustion load performance by up to 6.7% compared with traditional high-energy spark ignition but cannot significantly improve the lean combustion limit and stability. In addition, under each λ condition, the scavenging jet nozzle face toward one of the intake valves (IV2) is most advantageous. The effect of lean combustion on reducing NO began to manifest after λ > 1.3 and achieved the best at 1.6. This kind of jet ignition pre-chamber provides a more stable ignition solution than high-energy spark ignition for low speed and medium/low load aspects.]]></description>
      <pubDate>Wed, 27 Nov 2024 13:43:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/2444838</guid>
    </item>
    <item>
      <title>A Study on Fuel Spray Atomization Processes under Various Jet Configuration</title>
      <link>https://trid.trb.org/View/2413886</link>
      <description><![CDATA[In port fuel injection (PFI) gasoline engines, combustion fluctuations are caused by the interaction of various factors during ignition. Variations in the fuel deposition on the intake port walls cause fluctuations in the fuel supply to the combustion chamber and in the fuel concentration distribution, which causes knocking. In addition, when a large amount of fuel deposition occurs, it flows into the cylinder in liquid form without vaporizing, generating unburned hydrocarbons. In the previous report, the authors confirmed that the fuel adhesion amount on the port wall can be reduced by increasing the fuel injection pressure. In this paper, they investigated fuel atomization under even higher injection pressure conditions than the injection pressure range commonly used in intake port injection, with the aim of further reducing the amount of adhesion. In this paper, shadowgraph photography and Super High Spatial Resolution Photography were used to visualize and measure the free-spray jet morphology and atomization characteristics. The effect of high injection pressure to like direct injection, which on the Jet configuration and atomization characteristics of the spray. The results showed that the droplet diameter changed significantly from 1 to 3 MPa (Wavy region) to 4 MPa (Spray region), but no significant change was observed after 8 MPa (Spray region, Spray region with secondary breakup), and that the droplet diameter did not decrease after 8 MPa.]]></description>
      <pubDate>Mon, 23 Sep 2024 09:07:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/2413886</guid>
    </item>
    <item>
      <title>Experimental study on dribbling characteristics of gasoline/biodiesel blends after the end-of-injection</title>
      <link>https://trid.trb.org/View/2381807</link>
      <description><![CDATA[The effects of biodiesel addition on gasoline fuel dribbling process and characteristics after the end-of-injection (EOI) were investigated in a constant volume chamber at different injection pressures and ambient temperatures. The fuel dribbling process was recorded with high spatial and time resolution by using the microscopic shadow imaging technique, and the corresponding dribble velocity, dribble volume and droplet size were extracted. The results showed that the fuel dribbling experienced four typical morphological structures (spray-like, membrane-type, ligament-type, droplets) after the EOI under all the tested conditions. Additionally, increased biodiesel proportion in the blends caused decreased dribble velocity, longer dribbling duration, and increased droplet size, indicating deteriorated breakup and atomization processes of the dribbling flow. Moreover, the higher injection pressure increased the dribble amount but reduced the dribbling duration and droplet size. The increased ambient temperature caused faster evaporation of the dribbling fuel, resulting in a significant decrease in the dribble size. So, these two strategies were believed to be overall favorable to restrain the adverse effect on gasoline fuel dribbling characteristics caused by the addition of biodiesel.]]></description>
      <pubDate>Mon, 24 Jun 2024 09:26:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2381807</guid>
    </item>
    <item>
      <title>Measurement of needle and armature dynamics in a gasoline direct injector by high-speed neutron imaging</title>
      <link>https://trid.trb.org/View/2326015</link>
      <description><![CDATA[In modern spark ignition engines, precise delivery of fuel with gasoline direct injection has become increasingly important in the effort to meet ever stricter efficiency and emissions regulations. Use of multiple small close-coupled injections has become more common in attempt to precisely control fuel distribution in the cylinder, but these strategies are hindered by nonlinear injection effects due to operation in the ballistic region of the solenoid-operated valve and due to armature bounce at the end of injection. Understanding the internal dynamics of the injector is crucial to minimizing and controlling non-linearity and shot-to-shot variation, but the experimental techniques available to date are capable only of tracking the position of either the top of the needle (via laser sensors or by monitoring current and voltage in the solenoid coil) or the bottom of the needle (via transparent nozzles or high-speed x-ray imaging). A complete picture of the axial and radial motion of valve needle has until now remained elusive. In this work, the authors present high-speed ensemble neutron transmission imaging of an entire 8-hole gasoline direct injector operating at 200 bar, allowing for both visualization and quantification of the actuation dynamics including lift and wobble of the valve ball, oscillation and bending of the valve needle, lift, rocking, and bounce of the armature, compression of the springs, and radial swelling of the solenoid during energization. Because neutrons offer high penetration through the metal injector while also being sensitive to the 1H nuclei in fuel molecules, it is also possible to simultaneously see the fluid dynamics of the injection process, including filling of the sac volume, emanation of the spray through the nozzle holes and into the downstream gas, and the formation and evolution of fuel films on the tip of the injector and the walls of the spray container.]]></description>
      <pubDate>Tue, 19 Mar 2024 15:19:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/2326015</guid>
    </item>
    <item>
      <title>Effects of riser height and pipeline length on the transition boundary and frequency of severe slugging in offshore pipelines</title>
      <link>https://trid.trb.org/View/2347989</link>
      <description><![CDATA[Investigating the transition boundary and frequency characteristics of severe slugging under different riser heights and pipeline lengths provides important support for the expansion of offshore oil and gas to deeper waters. The visualization research on air-water two-phase flow is carried out in a system with a horizontal pipeline length of 1687 m and riser heights of 16 m, 22 m, and 29 m, and flow pattern maps are plotted. Based on existing experimental data, the database of the flow pattern and slugging frequency in pipeline-riser systems with riser heights of 3–29 m, pipeline lengths of 10–1687 m, and pipe diameters of 25.4–50.8 mm is established. The long pipeline makes the gas pressure growth rate slower than that of the liquid pressure in the riser, which causes severe slugging occurring at higher superficial gas velocity. On the contrary, increasing the riser height causes the boundary of severe slugging to shift to a lower superficial gas velocity. The severe slugging length is greater in the higher riser and longer pipeline system, causing a smaller severe slugging frequency. A correlation for predicting severe slugging frequency at various riser heights, pipe lengths, and pipe diameters is established by employing gas and liquid Froude numbers.]]></description>
      <pubDate>Tue, 19 Mar 2024 15:18:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/2347989</guid>
    </item>
    <item>
      <title>Effect of atomizer and cross-flows on liquid and gelled Jet A-1 fuel injection</title>
      <link>https://trid.trb.org/View/2325583</link>
      <description><![CDATA[The current study aims to experimentally investigate the effect of atomizer and cross-flow velocities on liquid and gelled Jet A-1 fuels. For gelled Jet A-1, Jet A-1 liquid, Thixatrol® ST and rectified xylene are the base fuel, gellant and solvent, respectively. Gelled Jet A-1 is prepared by adding 85% by weight of base fuel along with 7.5% by weight of gellant and solvent, each at optimum processing conditions. Atomization using a simple-plain-orifice atomizer is investigated to understand its effect on Jet A-1 gel fuel break-up without air cross-flow. Based on the investigation from qualitative flow visualization and quantitative analysis of Jet A-1 gel fuel break-up, a modified simple-plain-orifice atomizer called an internally impinging air-blast atomizer is made. Primary atomization using this new atomizer is studied to understand the break-up of liquid and gelled Jet A-1 gel fuels without any air cross-flow. Secondary atomization of liquid and gel fuel is investigated by transversely injecting fuel into different low-speed subsonic air cross-flow environments. Laser sheet Imaging (LSI) technique is used to capture spray images of both fuels. Break-up mechanisms of both liquid and gel fuels were observed, and the results were compared. Information on the cross-flow air mass flow rate effect on the liquid and gel spray is extracted by developing an algorithm in MATLAB using an image processing tool. Relative droplet size distribution of liquid and gel spray revealed their dependence on cross-flow air mass flow rate. Total droplet count of both liquid and gel fuel decreases significantly as the cross-flow Reynolds’ number increases. At higher cross-flow Reynolds’ number, gel droplets in the flow are observed to be more as compared to liquid fuel.]]></description>
      <pubDate>Fri, 15 Mar 2024 16:35:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2325583</guid>
    </item>
    <item>
      <title>Understanding hydrogen jet dynamics for direct injection hydrogen engines</title>
      <link>https://trid.trb.org/View/2287593</link>
      <description><![CDATA[The energy paradigm is shifting toward carbon-free and low-emission alternative fuels. Among the many candidates, hydrogen is considered a promising option thanks to its favorable fuel properties, including zero carbon content, high gravimetric energy density, and fast flame speed, despite its technical fuel production and storage challenges. Direct injection technology has been identified as the best approach for applying hydrogen in combustion engines to overcome the accompanying issues, such as backfire and low energy density. However, studies have yet to be conducted on hydrogen jet behavior in direct injection systems, specifically, studies that elucidate engine design and injection parameter optimization in the combustion system. Therefore, the authors aimed to assess hydrogen jet behavior through experiments and computational approaches comprehensively. Hydrogen was injected at 10 MPa using the direct injection method into a constant volume chamber under a quasi-steady ambient condition. Z-type high-speed Schlieren imaging was performed using a high-speed camera to visualize the hydrogen jet structure, which depicted the hydrogen jet’s vapor intermittency and vortex structure. The authors also performed a computational fluid dynamics (CFD) simulation to understand the aerodynamics of the jet. The results showed the formation of vortical flow in the inner core region, where the pressure was comparatively lower than that on the outer side of the jet. Their further investigation of the injection strategy showed that multiple injections were more beneficial in forming a favorable hydrogen-air mixture near the spark plug than a single injection case.]]></description>
      <pubDate>Fri, 22 Dec 2023 11:19:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2287593</guid>
    </item>
    <item>
      <title>An Experimental Study on DME Spray Characteristics and Evaporation Processes in a High Pressure Chamber</title>
      <link>https://trid.trb.org/View/1791664</link>
      <description><![CDATA[In this study, the spray characteristics and evaporating processes of DME fuel were investigated using the SCHLIEREN optical system and single-hole injectors in a constant volume chamber at room temperature. The photographs taken at different chamber pressures, injection pressures, orifice diameters and injection quantities were compared and analyzed. The results show that DME spray has a slower penetrating speed, wider spray angle, and much quicker evaporating processes than the diesel spray.]]></description>
      <pubDate>Thu, 07 Dec 2023 14:00:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/1791664</guid>
    </item>
    <item>
      <title>Experimental visualization of the gas-liquid two-phase flow inside the multi-cavity during reciprocating motion</title>
      <link>https://trid.trb.org/View/2237245</link>
      <description><![CDATA[The piston cooling of engines are usually controlled by the “cocktail shake” mechanism inside the single cooling cavity, according to most studies of piston cooling published before. This paper researched on flow in multiple cooling cavities which are extensively used on pistons of low-speed engines, revealing that the flow in multi-cavity is quite different from that in a single cooling cavity. In this work, complete reciprocating cycles are captured to study the gas-liquid two-phase flow behavior of each cavity inside the multi-cavity piston, by conducting synchronous experiments using benchmarked high-speed camera and a real size piston. The effects of different engine speeds (40–64?rpm) and different inlet pressures (0.1–0.3?MPa) were investigated. Both the inner and annular cavities are cooled mainly by cocktail shaking, but two cooling mechanisms are observed in the outer cavity, the oscillatory effect and cyclonic effect, providing further development on piston cooling studies. The cyclonic effect enhances the heat transfer capacity of the sidewall surfaces. The coupling effect between multiple cavities produces a secondary mixing effect of the liquid and improves the overall turbulence. In this paper, a comprehensive analysis of the flow mechanism within a typical multi-cavity piston is presented.]]></description>
      <pubDate>Wed, 27 Sep 2023 09:11:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/2237245</guid>
    </item>
    <item>
      <title>In-cylinder optical analysis of CRDI diesel engine combustion</title>
      <link>https://trid.trb.org/View/1791941</link>
      <description><![CDATA[The optimization of diesel engine performance and emissions can be achieved through a better understanding of the in-cylinder combustion process. Advanced non-intrusive optical techniques are providing new tools for investigating the thermo-fluid dynamics processes as well as they are contributing to develop predictive models for DI diesel combustion. High-speed images of spray and flame evolution as well as UV-visible chemiluminescence measurements were carried out in an optical 0.5-liter, single-cylinder, four-stroke, direct- injection diesel engine equipped with a prototype four valves cylinder head and a fully flexible CR injection system. In order to evaluate the effect of different injection strategies on the combustion process, measurements were performed varying injection parameters. The ignition location and time were individuated by combustion visualization and detection of radical species, obtained by chemiluminescence measurements. The spectral features of broadband flame emission characterized soot formation and its evolution.]]></description>
      <pubDate>Tue, 29 Aug 2023 16:47:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/1791941</guid>
    </item>
    <item>
      <title>Experimental investigation of boundary layer flow near the cylinder wall in a direct-injection spark-ignition engine using particle image velocimetry</title>
      <link>https://trid.trb.org/View/2173528</link>
      <description><![CDATA[In a direct-injection spark-ignition (DISI) optical engine with a constant motored speed of 800 rpm, particle image velocimetry measurements on the in-cylinder bulk flow and the boundary layer flow near the cylinder wall were performed during the intake and compression strokes. Two different tumble flow levels were explored using a flap inserted in the intake port. The near-wall flow pattern under the effect of the bulk flow is more stable when the flap is fully closed with a higher intensity tumble. The serious optical distortion in the near-cylinder wall region under high magnification was addressed, and a high resolution of 76 µm × 76 µm within a field of view of 5 mm × 5 mm was achieved in six different measurement regions. Using inner scaling parameters (friction velocity uₜ and viscous length-scale δᵤ), the dimensionless ensemble-averaged wall-tangential velocity profiles exhibit good consistency with the law-of-the-wall in the viscous sublayer but considerably departure in the logarithmic region. According to the low friction Reynolds number, the absence of the logarithmic layer was mainly attributed to the complete overlap between the viscosity-affected inner region and the outer region of the boundary layer. The near-wall velocity profiles were also normalized by three different outer scaling parameters. The collapse is significantly improved for y/δ >0.07 when the velocity profiles are normalized by δ/δ*(1-u/u∞). The fluctuation RMS velocity in the wall-normal direction is greater, particularly for the high tumble flow level condition.]]></description>
      <pubDate>Fri, 30 Jun 2023 11:28:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/2173528</guid>
    </item>
    <item>
      <title>Particulate Characterization of a DISI Research Engine using a Nephelometer and In-Cylinder Visualization</title>
      <link>https://trid.trb.org/View/1790803</link>
      <description><![CDATA[A nephelometer system was developed to characterize engine particulate emissions from DISI engines. Results were correlated with images showing the location and history of particulates in the cylinder of an optical engine. The nephelometer's operation is based upon the dependence of scattered laser light on particulate size from a flow sampled from the exhaust of an engine. The nephelometer simultaneously measured the scattered light from angles of 20° to 160° from the forward scattering direction in 4° increments. The angular scattering measurements were then compared with calculations using a Mie scattering code to infer information regarding particulate size. Measurements of particulate mass were made based upon a correlation developed between the scattered light intensity and particulate mass samples trapped in a 0.2-micron filter. Measurements were made in a direct injection single-cylinder spark ignition research engine having a transparent quartz cylinder. The engine was operated at a speed of 1000 rpm at partial load with both late and early fuel injection timings. The nephelometer measurements were complimented with in-cylinder PM visualization using planar Mie scattering imaging. Correlations were attempted between the nephelometer engine-out PM measurements and the in-cylinder visualized PM.]]></description>
      <pubDate>Thu, 22 Jun 2023 09:49:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1790803</guid>
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