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    <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" />
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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>Visible Light Communication-Enabled Simultaneous Position and Orientation Detection for Harnessing Multipath Interference and Random Fading</title>
      <link>https://trid.trb.org/View/2337209</link>
      <description><![CDATA[The authors focus on visible light communication-based simultaneous position and orientation detection (SPAO) for user devices (UDs) using photodiodes, which is challenging due to scattering interference and small-scale fading. To address this challenge, a novel SPAO approach is proposed, which can jointly estimate UD location parameters and scattering channel states. As such, the disturbance of diffuse scattering and random fading on SPAO will be alleviated via scattering channel equalization. In addition, SPAO is non-convex in nature, and hence brute-force application of conventional optimization methods will lead to a poor SPAO solution. To address this issue, they devise a majorization minimization (MM)-based SPAO algorithm, where hidden convex structure of the non-convex SPAO problem is exploited, which renders an efficient closed-form iteration rule for joint SPAO and diffuse channel estimation. Due to the cross-layer cooperation between “VLC” and “ranging”, a robust SPAO solution against diffuse scattering and small-scale fading is achieved. It is corroborated by their simulations that the proposed MM-based SPAO algorithm achieves a large performance gain over state-of-the-art baseline methods.]]></description>
      <pubDate>Wed, 03 Jul 2024 09:04:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/2337209</guid>
    </item>
    <item>
      <title>2D Diesel Spray Droplet Size Mapping Based on Planar Laser Induced Fluorescence and Mie-Scattering Technique Using Sparsity Deconvolution</title>
      <link>https://trid.trb.org/View/2367383</link>
      <description><![CDATA[The distribution of spray droplet sizes plays a pivotal role in internal combustion engines, directly affecting fuel-air mixing, evaporation, and combustion. To gain a precise understanding of droplet size distribution in a two-dimensional space, non-intrusive optical diagnostics emerge as a highly effective method. In the current investigation, two-dimensional (2D) diesel spray droplet sizes mapping using a simultaneous combination of planar laser-induced fluorescence (PLIF) and Mie-scattering techniques is introduced. The assessment of droplet diameter relies on the interplay between fluorescent and scattered light intensities which correspond the light based on volumetric droplets and surface area of the droplets. This calculation is made possible through the LIF/Mie technique. However, traditional LIF/Mie methods are plagued by inaccuracies arising from multiple light scattering. To overcome this challenge and to attain higher accuracy than conventional LIF/Mie technique, the authors introduce a sparsity deconvolution approach to eliminate unwanted light interference on both LIF and Mie images. The core concept of sparsity deconvolution is to reduce disturbances caused by multiple scattering and offer sharp and finely detailed images for LIF/Mie ratio estimation. To enhance spatial sharpness and remove the undesired scattering light, an iterative Richardson–Lucy (RL) and Land Weber (LW) filters are introduced for image deconvolution. The results reveal that RL deconvolution is particularly well-suited for the intricate task of deconvolving complex liquid sprays, producing sharper and finer detailed droplet images. Additionally, the further calibration of 2D droplet size mapping based on microscopic method is implemented to approximate the linear fitting curve of dependence between macro LIF/Mie ratio and droplet diameter. This comprehensive approach advances the understanding of the critical role played by droplet size distribution under engine-like conditions.]]></description>
      <pubDate>Sun, 05 May 2024 17:28:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/2367383</guid>
    </item>
    <item>
      <title>Quantifying extinction imaging of fuel sprays considering scattering errors</title>
      <link>https://trid.trb.org/View/2287605</link>
      <description><![CDATA[In this work, the authors use the measurement technique of high-speed Diffuse Back Illumination Extinction Imaging (DBI-EI) to obtain quantitative information in the form of projected liquid volume (PLV) in a highly transient GDI process. For the DBI-EI setup they use a LED-Panel as the light source, which fulfills diffuse back illumination extinction imaging criteria. Measurements were carried out in a constant volume chamber, allowing easy optical access, and enabling measurements at real world ambient engine conditions. For the experiments, the authors use an Engine Combustion Network (ECN) Spray G injector and measure the sprays at ECN conditions. Moreover, they mount the injector in a motorized rotational system, enabling measurements of the sprays at precisely defined angles of observation. The DBI-EI technique requires a light source radiating uniformly in a certain range of an angle. Because of the diffuse radiation, an error in the quantification of the liquid phase results from the detection of multiple and forward scattered photons. This leads to an underestimation of the optical depth (OD), which further results in a false calculation of the projected liquid volume. Therefore, the authors must assume that DBI-EI results are wrong. To enable the use of DBI-EI in all spray regions independent of the measurement setup, they present a simulation-based method, which is correcting the OD for scattering effects. Results show, that the measured OD of the experimental setup, which was used in this work, is underestimated by at least a factor of 2.2. This factor increases with increasing spray densities. The authors can use the corresponding corrected PLV data to reconstruct three-dimensional data of the liquid volume fraction with the tomographic method filtered back projection. Thus, they obtain time and spatial resolved quantitative spray information, with an approach to correct undesired scattering effects, while keeping the experimental effort low.]]></description>
      <pubDate>Fri, 22 Dec 2023 11:19:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2287605</guid>
    </item>
    <item>
      <title>Multi-Attention DenseNet: A Scattering Medium Imaging Optimization Framework for Visual Data Pre-Processing of Autonomous Driving Systems</title>
      <link>https://trid.trb.org/View/2082442</link>
      <description><![CDATA[The vision system is important for almost all kinds of autonomous driving systems. However, visual data interfered by scattering media, such as smoke, haze, water, and other non-uniform media will be degraded seriously, showing the characteristics of detail loss, poor contrast, low visibility, or color distortion. These characteristics can significantly interfere with the reliability of autonomous driving systems. In real environments the image degradation mechanism is complex, and the estimation of degradation parameters is difficult. This issue remains to be solved. In this study, the authors employed dense blocks as the framework and introduced the attention mechanism to their model from four dimensions: Multi-scale Attention, Channel Attention, Structure Attention, and ROI (region of interest) Attention. With the help of the training data provided by the weakly supervised model, the proposed method achieved excellent performance in the task of scattering medium imaging optimization in different scenes. Comparative experiments show that the proposed method is robust, and is superior to other state-of-the-art methods in image dehazing, and underwater image enhancement tasks. It is of great significance to improve the reliability of autonomous driving systems in underwater and severe weather environments.]]></description>
      <pubDate>Sun, 30 Apr 2023 16:54:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2082442</guid>
    </item>
    <item>
      <title>Experimental investigations on the integrated bubbly wake strength of two different scale ship models</title>
      <link>https://trid.trb.org/View/2014681</link>
      <description><![CDATA[The integrated bubbly wake strength of two ship models with different scales is investigated in this paper. The laser spot video recording technique is implemented to measure the light scattering properties of laser beams transmitted through the wake. The bubbly wake is generated by the movement of two geometrically similar models towed at constant velocities in a towing tank. The effect of the model’s velocity and scale are investigated using data provided by the multiple laser emitter and detectors. Results show the dominance of small bubbles on the persistence of the wake. Also, the effects of wetness of the stern on the vertical distribution of the wake are evident. Comparing the wake of two scale models shows a stronger wake for the bigger model in similar conditions. Moreover, the importance of Froude and Weber numbers on the scaling of major features of the bubbly wake of ship models is prominent.]]></description>
      <pubDate>Wed, 30 Nov 2022 10:59:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2014681</guid>
    </item>
    <item>
      <title>Numerical Investigation of an Optical Soot Sensor for Modern Diesel Engines</title>
      <link>https://trid.trb.org/View/1818279</link>
      <description><![CDATA[It has been extensively evidenced that modern diesel engines generate a considerable amount of soot nanoparticles. Existing soot sensors are not suitable for such nanoparticles. Current standard gravimetric techniques are extremely insensitive to fine soot particles. Soot diagnostics developed for research purposes, e.g., laser induced-incandescence, do not provide quantitative characterization, and expanded practical applications of these techniques are hardly conceivable. This paper addresses this emerging need for monitoring nano-sized soot emissions. Here, the authors investigated the use of polarization modulated scattering (PMS) for soot sensing in engine environments. The technique involves 1) measuring laser scattering by soot particles at multiple angles while varying the polarization states of the incident laser beam, 2) determining multiple elements of the Mueller matrix from the measured signals, and 3) inferring properties of the soot particles from these elements. This paper details the sensing concept and the algorithm used to retrieve soot characteristics.]]></description>
      <pubDate>Mon, 24 Oct 2022 10:22:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/1818279</guid>
    </item>
    <item>
      <title>A Light Scattering Study of the Aggregation Kinetics of Carbon Black Suspensions in Group 1 and Group 2 Base Oils. Influence of Dispersant Additives</title>
      <link>https://trid.trb.org/View/1797324</link>
      <description><![CDATA[The stabilization of non-dispersed particles against aggregation is a major challenge for diesel lubricant formulators. New engine technologies, especially exhaust gas recirculation (EGR), and the increase in drain intervals have given rise to increasingly soot-laden oils. To help formulators understand these complicated systems, the additive chemists might study aggregation of the colloidal particles such as Carbon Black suspensions by Light Scattering techniques. The connection of such experiments is discussed taking into consideration of aggregation kinetics of colloidal particles, in particular it is shown that the time evolution of fractal aggregates of Carbon Black particles leads to the stability parameter W. From the Light Scattering experiments it is found that Group I and Group II base oils behave differently as regards Carbon Black stability. In the case of a Group I base oil, no aggregation is observed, whereas in the presence of a Group II base oil, a large increase of the aggregates is measured. This result is poorly understood and at odds with some other experiments. The effect of dispersants in a Group I base oil is to reduce slightly the size of the aggregates. In a Group II base oil, depending on the type of dispersant, the aggregation kinetics is either slowed down or stopped. These results are confirmed by sedimentation and confocal microscopy techniques. Finally, using a relation which links W to the Van der Waals' steric and electrostatic potentials and numerical values from the literature, the relative influence of attractive and repulsive forces is considered in the case of the Group II base oil.]]></description>
      <pubDate>Mon, 26 Sep 2022 09:12:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/1797324</guid>
    </item>
    <item>
      <title>Evaluation of Transient Performance of Diesel Particulate Filters via Light Extinction and Scattering methods</title>
      <link>https://trid.trb.org/View/1813604</link>
      <description><![CDATA[The performance of diesel particulate filters (DPF) was assessed by means of the light extinction and scattering methods using three common-rail turbo-charged DI diesel engines. The temporal soot mass concentrations measured by the extinction method before and after DPF showed filtration efficiency over 90% under steady conditions, while it fluctuated widely under transient modes due to the temporal delay in filtration process. The soot aggregate size measured by the Rayleigh-Debye scattering approach ranged from 80 nm to 140 nm depending on the engine operating conditions, and showed little change while particles were filtrated in DPF. Simultaneous measurements of mass concentration and radius of gyration of soot aggregates under JE05 transient mode were successfully performed using a 4 liter common-rail diesel engine.]]></description>
      <pubDate>Mon, 26 Sep 2022 09:12:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1813604</guid>
    </item>
    <item>
      <title>Effects of Injection Timing and Duration on Fuel-Spray Collapse and Wall-Wetting in a Stratified Charge SI Engine</title>
      <link>https://trid.trb.org/View/1856133</link>
      <description><![CDATA[Fuel-lean combustion using late injection during the compression stroke can result in increased soot emissions due to excessive wall-wetting and locally unfavorable air-fuel mixtures due to spray collapse. Multi-hole injectors, most commonly used, experiencing spray collapse, can worsen both problems. Hence, it is of interest to study the contribution of spray collapse to wall-wetting to understand how it can be avoided. This optical-engine study reveals spray characteristics and the associated wall-wetting for collapsing and non-collapsing sprays, when systematically changing the intake pressure, injection duration and timing. High-speed imaging of Mie-scattered light was used to observe changes in the spray structure, and a refractive index matching (RIM) technique was utilized to detect and quantify the area of fuel-film patterns on bottom of the piston bowl. E30 (gasoline blended with 30% ethanol by volume) was used throughout the experiments. E30 is known to be more susceptible to spray collapse and the high heat of vaporization of ethanol tends to exacerbate fuel-film formation. These experimental results highlight the impact of in-cylinder ambient conditions on spray morphology and the influence of spray behavior on fuel-films. Analysis of the spray images reveals that spray collapse is a strong function of in-cylinder density and its evolution in spite of the changes in in-cylinder pressure, temperature, and flow at the operating condition used in this study. This explains similarities in the degree of spray collapse and resultant wall-wetting from various injection timings and intake pressures. It is also found that at operating conditions where the spray undergoes transition from non-collapsing to collapsing spray during an injection event, both fuel-film area and variability in fuel-film pattern increased.]]></description>
      <pubDate>Sat, 29 Jan 2022 18:12:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/1856133</guid>
    </item>
    <item>
      <title>Development of a High Sensitivity and High Response Smoke Meter</title>
      <link>https://trid.trb.org/View/1500248</link>
      <description><![CDATA[For a wide detection range of soot mass concentration and fast response, a laser smoke meter based on light scattering and light extinction was developed. A common rail, turbo-charged diesel engine was used in calibration of soot mass concentration measurements. As a result, the laser smoke meter was found to have a minimum detection sensitivity of 0.01mg/m³. The practical calibration of the light scattering mode which is applied to low soot concentration measurements was carried out using the light extinction method. Continuous measurements of a wide range of 0.01-1000mg/m³ were performed by combination of extinction and scattering methods.広いSoot検出濃度範囲と高応答を実現するために，光減衰法及び光散乱法の計測を同時に行うスモークメータを開発した．ディーゼルエンジンを用いてSoot濃度の校正を行い，0.01～1000mg/m³のSoot濃度を立ち上がり時間0.3秒の応答性で計測可能であることを確認した．]]></description>
      <pubDate>Tue, 26 Jun 2018 10:15:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/1500248</guid>
    </item>
    <item>
      <title>Optimization and Design of Wireless Systems for the Implementation of Context Aware Scenarios in Railway Passenger Vehicles</title>
      <link>https://trid.trb.org/View/1485013</link>
      <description><![CDATA[In this paper, intra-wagon wireless communication performance is analyzed, in order to account for inherent scenario complexity in the deployment phase of wireless systems toward the implementation of a context-aware environment. A real commercial passenger wagon has been simulated by means of an in-house-developed 3-D ray launching code, accounting for embedded wagon elements as well as variable user densities within the passenger wagon. Onboard measurements of a designed and deployed wireless sensor network are obtained, showing good agreement with wireless channel estimations for two different frequencies of operation. Energy consumption behavior and user density impact have also been analyzed and estimated as a function of network topology and the operational mode. These results can aid in wireless transceivers deployment configurations, in order to minimize power consumption, optimize interference levels, and increase overall service performance.]]></description>
      <pubDate>Fri, 27 Oct 2017 09:28:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1485013</guid>
    </item>
    <item>
      <title>A Novel Diagnostics Tool for Measuring Soot Agglomerates Size Distribution in Used Automotive Lubricant Oils</title>
      <link>https://trid.trb.org/View/1433890</link>
      <description><![CDATA[The determination of size distribution of soot particles and agglomerates in oil samples using a Nanosight LM14 to perform Nanoparticle Tracking Analysis (NTA) is described. This is the first application of the technique to sizing soot-in-oil agglomerates and offers the advantages of relatively high rates of sample analysis and low cost compared to Transmission Electron Microscopy (TEM). Lubricating oil samples were drawn from the sump of automotive diesel engines run under a mix of light duty operating conditions. The oil samples were diluted with heptane before analysing. Results from NTA analysis were compared with the outputs of a more conventional analysis based on Dynamic Light Scattering (DLS). This work shows that soot-in-oil exists as agglomerates with average size of 115 nm. This is also in good agreement with TEM analysis carried out in a previous work. NTA can measure soot particles in polydisperse oil solutions and report the size distribution of soot-in-oil aggregates. NTA allows for an estimation of soot mass contained in the soot-laden oil samples. The estimated value was compared with soot mass measured using Thermo-Gravimetric Analysis.]]></description>
      <pubDate>Thu, 05 Jan 2017 16:23:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1433890</guid>
    </item>
    <item>
      <title>Trajectory Measurements of a Horizontally Oriented Buoyant Jet in a Coflow Using Filtered Rayleigh Scattering</title>
      <link>https://trid.trb.org/View/1416845</link>
      <description><![CDATA[The filtered Rayleigh scattering technique was implemented to discern the mechanisms associated with trajectory and mixing characteristics of buoyant jets in the presence of a coflow. A continuous wave laser in conjunction with a high-speed camera and a molecular filter constituted the equipment needed to obtain near-field concentration measurements of a carbon dioxide jet within a coflow of air. The arrangement enabled carbon dioxide concentration measurements with and without the coflow at a sampling rate of 400 Hz. The time-averaged results demonstrate the significance that adding the coflow has on increasing the mixing rate, thus reducing the impact of the buoyant jet by flattening the jet trajectory. The effects of various flow parameters such as the jet velocity, the jet to coflow velocity ratio, the relative velocity between the jet and the coflow, and the Froude number on the jet trajectory are studied. The downward trajectory of the carbon dioxide jet, absent a coflow, was well correlated with the Froude number. However, the addition of the coflow led to a substantial impact on the jet trajectory, reducing its buoyant effects due to a combination of increased momentum and, likely, the mixing rate. Further increases in the coflow, including the relative magnitude of the coflow, had a lesser impact. Mixing characteristics and time-dependent jet motion were captured.]]></description>
      <pubDate>Fri, 30 Sep 2016 16:32:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/1416845</guid>
    </item>
    <item>
      <title>Impacts of Fog Characteristics, Forward Illumination, and Warning Beacon Intensity Distribution on Roadway Hazard Visibility</title>
      <link>https://trid.trb.org/View/1409269</link>
      <description><![CDATA[Warning beacons are critical for the safety of transportation, construction, and utility workers. These devices need to produce sufficient luminous intensity to be visible without creating glare to drivers. Published standards for the photometric performance of warning beacons do not address their performance in conditions of reduced visibility such as fog. Under such conditions light emitted in directions other than toward approaching drivers can create scattered light that makes workers and other hazards less visible. Simulations of visibility of hazards under varying conditions of fog density, forward vehicle lighting, warning beacon luminous intensity, and intensity distribution were performed to assess their impacts on visual performance by drivers. Each of these factors can influence the ability of drivers to detect and identify workers and hazards along the roadway in work zones. Based on the results, it would be reasonable to specify maximum limits on the luminous intensity of warning beacons in directions that are unlikely to be seen by drivers along the roadway, limits which are not included in published performance specifications.]]></description>
      <pubDate>Tue, 28 Jun 2016 16:37:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/1409269</guid>
    </item>
    <item>
      <title>Visibility monitoring using conventional roadside cameras - Emerging applications</title>
      <link>https://trid.trb.org/View/1136862</link>
      <description><![CDATA[The measurement of atmospheric visibility is an important element for road and air transportation safety. This paper proposes a novel estimator of the atmospheric visibility by already existing conventional highway cameras, with a technique based on the gradient magnitude selected by applying Lambert's law with respect to changes in lighting conditions. The response of this estimator is calibrated by non-linear regression with data from a visibility meter installed in a test site which has been instrumented with a camera. Through the technique, atmospheric visibility estimates are obtained with an average error of 30% for images taken in the day, with sky luminance between 10 and 8000 cd mâ-2 and visibility distances up to 15 km. Results allow one to envision practical implementation on roadsides in the near future to determine local visibility for the benefit of road safety, meteorological observation and air quality monitoring.]]></description>
      <pubDate>Wed, 16 May 2012 15:05:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1136862</guid>
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