<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>Optimization Research on the Electromagnetic Noise of EMU Traction Motors</title>
      <link>https://trid.trb.org/View/2598868</link>
      <description><![CDATA[The comfort assessment for high-speed train passengers is becoming increasingly stringent, with noise being a key indicator. This paper focuses on the phenomenon of noise exceeding standards in a specific high-speed train, conducting noise testing research to identify the traction system noise as the major contributor. By optimizing the design of the traction motor and its control strategy, considering the motor slot coordination and control strategies, the noise caused by electromagnetic forces leading to motor resonance radiation was eliminated. The optimization results were significant, providing experiential guidance for noise optimization in other high-speed train motors.]]></description>
      <pubDate>Thu, 20 Nov 2025 17:07:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/2598868</guid>
    </item>
    <item>
      <title>Toward Near-Field 3D Spot Beam Focusing: Possibilities, Challenges, and Use Cases</title>
      <link>https://trid.trb.org/View/2559314</link>
      <description><![CDATA[Spot beam focusing (SBF) is the process of focusing the signal power in a small spot-like region in the 3D space, which can be either hard-tuned (HT) using traditional tools like lenses and mirrors or electronically reconfigured (ER) using modern large-scale intelligent surface phased arrays. ER-SBF (simply called SBF) can be a key enabling technology for next-generation 6G wireless networks, offering benefits to many future wireless application areas, such as wireless communication and security, midrange high-power and safe wireless battery-charging systems, medical and health, physics, etc. Although near-field HT-SBF and ER-beam focusing have been studied in the literature and applied in the industry, there is no comprehensive study of different aspects of SBF and its future applications, especially for nonoptical [millimeter-wave (mmWave), sub-terahertz (sub-THz), and THz] electromagnetic (EM) waves in next-generation wireless technology, which is the aim of this article. The theoretical concepts behind SBF, different antenna technologies for implementing SBF, employing machine learning (ML)-based schemes as enablers of beam training for SBF, and different practical application areas that can benefit from SBF will be explored.]]></description>
      <pubDate>Thu, 26 Jun 2025 11:42:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/2559314</guid>
    </item>
    <item>
      <title>Analysis of Vibration Reduction of Single-Side Permanent Magnet Synchronous Linear Motor by Using Hybrid-Type PMs</title>
      <link>https://trid.trb.org/View/2511524</link>
      <description><![CDATA[The normal electromagnetic force wave plays a critical role in electromagnetic vibration of permanent magnet synchronous linear motors (PMSLMs). In this article, a PMSLM designed with hybrid-type permanent magnets (PMs) is proposed aiming at enhancing the vibration performance through optimizing the harmonics component of the normal electromagnetic force wave. First, the normal force wave of the PMSLM is analyzed theoretically, and the main frequency of the normal force wave that affects the vibration of the PMSLM is obtained. Second, the electromagnetic characteristics are analyzed. Compared with the traditional PMSLM with single-type PMs, it is shown that the proposed PMSLM is capable of decreasing the thrust force ripple and normal force value without reducing the thrust force value. The temporal and spatial harmonic characteristics of normal force wave of the two PMSLMs are analyzed contrastively. In the end, the vibration behaviors of two PMSLMs are investigated by multiphysics FEA model based on modal superposition method, and this work is verified by the experiment.]]></description>
      <pubDate>Tue, 22 Apr 2025 15:51:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511524</guid>
    </item>
    <item>
      <title>Channel Measurement and Modeling for Millimeter-Wave Automotive Radar</title>
      <link>https://trid.trb.org/View/2389323</link>
      <description><![CDATA[Millimeter-wave (mmWave) automotive radar can detect the surrounding environment using highly directional, high-frequency electromagnetic waves. With these advantages, mmWave radar has become an important component of autonomous driving and integrated sensing systems. Designing systems and sensing algorithms requires the application of realistic channel models and simulation. In this paper, the propagation channel is measured, characterized, and modeled for mmWave automotive radar with typical configurations in scenarios. Based on the channel measurements in urban street and expressway environments, ray-tracing (RT) technology is verified for modeling important objects regarding radar cross-section and echo power. A hybrid channel model is proposed by integrating RT with the stochastic modeling of targets and surrounding environments, which significantly improves simulation efficiency and provides more flexibility for virtual tests in various complex environments.]]></description>
      <pubDate>Wed, 31 Jul 2024 16:26:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2389323</guid>
    </item>
    <item>
      <title>Enhancement of Satellite-To-Phone Link Budget: An Approach Using Distributed Beamforming</title>
      <link>https://trid.trb.org/View/2319189</link>
      <description><![CDATA[Small satellites in low-Earth orbit (LEO) attract much attention from both industry and academia. The latest production and launch technologies constantly drive the development of LEO constellations. However, wideband signals, except text messages or voice in a few Kbps, cannot be transmitted directly from a LEO satellite to a standard mobile cellular phone due to the insufficient link budget. The current LEO constellation network has to use an extra ground device to receive the signal from the satellite first and then forward the signal to the user equipment (UE). To achieve direct network communications between LEO satellites and UE, in this article, the authors propose a novel distributed beamforming technology based on the superposition of electromagnetic (EM) waves radiated from multiple satellites that can significantly enhance the link budget. EM full-wave simulation and Monte Carlo simulation results are provided to verify the effectiveness of the proposed method. The simulation results show a nearly 6-dB enhancement using two radiation sources and an almost 12-dB enhancement using four sources. The received power enhancement could be doubled compared to the diversity gain in multiple-input, single-output (MISO). Furthermore, other practical application challenges, such as synchronization and the Doppler effect, are also presented.]]></description>
      <pubDate>Fri, 26 Jan 2024 10:02:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/2319189</guid>
    </item>
    <item>
      <title>Numerical simulation of the surface microwave heating efficiency of cement-based metamaterial absorbers in specific bands</title>
      <link>https://trid.trb.org/View/2316343</link>
      <description><![CDATA[Concentrating electromagnetic (EM) heat losses on the surface for road microwave deicing have been used to increase the efficiency of surface microwave heating. Here, a numerical model to enhance the surface EM losses based on metamaterial absorbers (MMAs) was developed and validated using experiments with cement as the thermal medium. The model included structure optimization, analysis for characterization of the surface loss mechanism, and tested for determination of the surface heating efficiency. Using the optimized structures, the efficiency of surface microwave heating improved by fivefold when compared to conventional road structures. These effects were consistent across tested and simulated results. In summary, the potential of implementing MMAs for road microwave deicing is highlighted to improve surface microwave heating efficiency.]]></description>
      <pubDate>Tue, 23 Jan 2024 09:16:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/2316343</guid>
    </item>
    <item>
      <title>Performance analysis of RIS-assisted V2V communication under multipath interference</title>
      <link>https://trid.trb.org/View/2298730</link>
      <description><![CDATA[Reconfigurable Intelligent Surface (RIS) enables precise modulation and directional transmission of signals by controlling the phase and amplitude of electromagnetic waves, thus solving the problems of signal fading, multipath effects, and interference faced by conventional wireless communication systems. In this paper, the RIS-assisted vehicle-to-vehicle (V2V) communication system under multipath interference was proposed, and the precise approximation for RIS-assisted V2V communication under Nakagami-m channels was derived in detail. Then, a comprehensive analysis of the key performance metrics of the system was performed, and analytical expressions for the outage probability, average bit error rate (BER), and average channel capacity were obtained thoroughly. The authors also validate all the analytical results through simulations. Furthermore, through comparative analysis, it is evident that increasing the number of RIS reflecting elements and optimizing the communication channel environment can significantly reduce the outage probability, average BER, increase the average channel capacity, and mitigate the impact of interference sources on the system.]]></description>
      <pubDate>Fri, 22 Dec 2023 08:46:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/2298730</guid>
    </item>
    <item>
      <title>Radars in Transport Applications</title>
      <link>https://trid.trb.org/View/1975594</link>
      <description><![CDATA[In the recent years, automotive car industry is evolving towards a new generation of autonomous vehicles, where decision making is not fully perform by the driver but it partially relies on the technology of the car itself. Indeed, a CPU inside the car will process all information coming from the sensors, distinguishing different scenarios appearing in the real life and ultimately allowing decision making. Since the CPU will be confronted with plenty of information, tools like machine learning or big-data analysis will be a useful ally to separate data from information. These existing machine learning techniques, such as kernel Principal Component Analysis (k-PCA), Locally Linear Embedding (LLE) among many other techniques, are useful to unveil the latent parameters defining a given scenario. Indeed, these algorithms have been already used to perform real-time classification of signals appearing throughout the road. Selecting the modeling of the electromagnetic response of the radar plays an important role to achieve real time constraints. Even though Helmholtz equation represents accurately the physics, the computational cost of such simulation is not affordable for real-time applications due to high radar operating frequencies, resulting into a very fine finite element mesh. On the other hand, far field approaches are not so accurate when the objects are very close due to plane wave assumption. In the first part of this work, the Geometrical Optics method is investigated in this work as a possible route to fulfill both real-time and accuracy constraints. The main hypothesis under such model is that waves are treated as straight lines constrained to optical reflection laws. Therefore, there is no need to mesh the interior of the domain. However, the accuracy of such approach is compromised when the size of the objects inside the domain are comparable to the wave lengths or in the vicinity of angular points. The second part is mainly focused on of the application of manifold learning and big data analysis into a data set of precomputed scenarios. Indeed, the identification of an unknown scenario from electromagnetic signals is purchased. Nevertheless, current research lines are devoted to give an answer to questions such as how many receptors do we need to identify unequivocally the scenario, where to locate the receptors, or which parts of the scenario have a negligible impact in the electromagnetic response.]]></description>
      <pubDate>Mon, 11 Sep 2023 11:39:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/1975594</guid>
    </item>
    <item>
      <title>Reconfigurable Intelligent Surface-Aided Joint Radar and Covert Communications: Fundamentals, Optimization, and Challenges</title>
      <link>https://trid.trb.org/View/2012456</link>
      <description><![CDATA[Future wireless communication systems will evolve toward multifunctional integrated systems to improve spectrum utilization and reduce equipment sizes. Joint radar and communication (JRC) systems, which can support simultaneous information transmission and target detection, have been regarded as a promising solution for emerging applications, such as autonomous vehicles. In JRC, data security and privacy protection are critical issues. Thus, the authors apply covert communication to JRC and propose a joint radar and covert communication (JRCC) system to simultaneously achieve high spectrum utilization and secure data transmission.]]></description>
      <pubDate>Tue, 04 Oct 2022 09:18:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2012456</guid>
    </item>
    <item>
      <title>Reconfigurable Intelligent Surfaces in Action for Nonterrestrial Networks</title>
      <link>https://trid.trb.org/View/2012455</link>
      <description><![CDATA[Next-generation communication technology will be made possible by cooperation between terrestrial networks with nonterrestrial networks (NTNs) composed of high-altitude platform stations (HAPSs) and satellites. Further, as humanity embarks on the long road to establish new habitats on other planets, the cooperation between NTNs and deep-space networks (DSNs) will be necessary. In this regard, the authors propose the use of reconfigurable intelligent surfaces (RISs) to improve coordination between these networks given that RISs perfectly match the size, weight, and power (SWaP) restrictions of operating in space. A comprehensive framework of RIS-assisted nonterrestrial and interplanetary communications is presented that pinpoints challenges, use cases, and open issues. Furthermore, the performance of RIS-assisted NTNs under environmental effects, such as solar scintillation and satellite drag, is discussed in light of simulation results.]]></description>
      <pubDate>Tue, 04 Oct 2022 09:18:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2012455</guid>
    </item>
    <item>
      <title>Multi-Target Tracking Algorithm in the Complicated Road Condition for Automotive Millimeter-wave Radar</title>
      <link>https://trid.trb.org/View/1834083</link>
      <description><![CDATA[Automotive radar is the most important component in the autonomous driving system, which detects the obstacles, vehicles and pedestrians around with acceptable cost. The target tracking is one of the key functions in the automotive radar which estimates the position and speed of the targets having regarding to the measurement inaccuracy and interferences. Modern automotive radar requires a multi-target tracking algorithm, as in the radar field of view hundreds of targets can present. In practice, the automotive radar faces very complicated and fast-changing road conditions, for example tunnels and curved roads. The targets’ unpredictable movements and the reflections of the electromagnetic wave from the tunnel walls and the roads will make the multi-target tracking a difficult task. Such situation may last several seconds so that the continuous tracks of the targets cannot be maintained and the tracks are dropped mistakenly. In the adaptive cruise control (ACC) system, non-continuous tracks leads to poor system performance, e.g. unwanted dangerous acceleration due to the target lost and unwanted sudden brake when previously dropped targets by mistake are tracked again. This paper presents a robust target tracking algorithm in the authors radar prototype which can maintain continuous track of the targets. This algorithm is verified in road tests on vehicle.]]></description>
      <pubDate>Wed, 23 Feb 2022 16:16:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/1834083</guid>
    </item>
    <item>
      <title>Joint Modulations of Electromagnetic Waves and Digital Signals on A Single Metasurface Platform to Reach Programmable Wireless Communications</title>
      <link>https://trid.trb.org/View/1878881</link>
      <description><![CDATA[In current wireless communication and electronic systems, digital signals and electromagnetic (EM) radiation are processed by different modules. Here, the authors propose a mechanism to fuse the modulation of digital signals and the manipulation of EM radiation on a single programmable metasurface. The programmable metasurface consists of massive subwavelength-scale digital coding elements. A set of digital states of all elements forms simultaneous digital information roles for modulation and the wave-control sequence code of the programmable metasurface. By designing digital coding sequences in the spatial and temporal domains, the digital information and far-field patterns of the programmable metasurface can be programmed simultaneously and instantly in desired ways. For the experimental demonstration of the mechanism, the authors present a programmable wireless communication system. The same system can realize transmissions of digital information in single-channel modes with beam-steerable capability and multichannel modes with multiple independent information. The measured results show the excellent performance of the programmable system. This work provides excellent prospects for applications in fifth- or sixth-generation wireless communications and modern intelligent platforms for unmanned aircrafts and vehicles.]]></description>
      <pubDate>Wed, 17 Nov 2021 14:25:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/1878881</guid>
    </item>
    <item>
      <title>Time-Frequency Analysis of GPR Simulation Signals for Tunnel Cavern Fillings Based on Short-Time Fourier Transform</title>
      <link>https://trid.trb.org/View/1848396</link>
      <description><![CDATA[The most important factor in restricting safe and efficient is the unfavorable geological conditions ahead of the tunnel face during tunnel construction in karst area. To avoid the occurrence of geological disasters, advanced geological forecast technology is widely used to detect the development of unfavorable geological bodies. In order to better explain the time-frequency characteristics of GPR signals of tunnel cavern fillings, the Gaussian window function is selected according to the uncertainty principle, and the short-time Fourier transform is used to analyze and process the GPR signals of cavern fillings with different properties based on forward simulation. The results show that the time-frequency spectrum based on short-time Fourier transform can meticulously describe the process of change that takes places in time and frequency plane of GPR signals, which is beneficial to accurately extract the time-frequency characteristic parameters in GPR signals. When the electromagnetic wave wavelength of the GPR transmitting antenna is shorter than the detection depth of cavern fillings, two target reflectors which reflect the upper and lower reflecting interfaces of the fillings will appear in the spectrum of forward simulation signal. The relative errors of recognition results obtained according to the reflection time interval are all less than 5%, which provides a reference for the quantitative interpretation of GPR signals of tunnel cavern fillings.]]></description>
      <pubDate>Tue, 25 May 2021 16:20:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/1848396</guid>
    </item>
    <item>
      <title>Analysis of the Earth's Surface Influence on the Accuracy of ADF Alignment</title>
      <link>https://trid.trb.org/View/1757387</link>
      <description><![CDATA[The article analyzes the interaction of electromagnetic waves of a radio navigation signal with the relief of the earth’s surface and its electrical properties. As a result of this interaction, such physical phenomena are created that have a significant negative effect on the accuracy of the Automatic Direction Finder's (ADF’s) alignment of the Non-Directional Beacon (NDB) signal. One of the two objectives of the article is to acquaint the aviation public with the physical nature of this natural phenomenon in terms of flight safety, which occurs to a large extent especially in mountainous countries, including Slovakia. The second goal of the article is to inform the professionals in the field about this phenomenon in terms of its nature as a physical law, in order to find ways to increase the accuracy of measurement of this navigation system.]]></description>
      <pubDate>Sun, 31 Jan 2021 15:49:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1757387</guid>
    </item>
    <item>
      <title>Research on modeling and simulation in overshadowing influence of coastal building on vessel traffic service radar</title>
      <link>https://trid.trb.org/View/1711789</link>
      <description><![CDATA[The reflection characteristics of radar waves in coastal high-rise buildings form a certain shielding area, which makes it difficult for vessel traffic service to control the ship dynamic situation in sheltered waters. To study the overshadowing influence of coastal buildings on the vessel traffic service radar, an expression model of shielding area is established based on the structure characteristics of buildings and the relative height of radar. Then, the coordinate system is established, and the range and height of the shelter area are calculated, according to the geometric relation. Based on the theory of radar electromagnetic wave diffraction, the target height is calculated. Finally, taking the Prince’s Bay Cruise Terminal Building on the radar Shekou radar as an example, the shielding area and height are calculated and visualized by the numerical calculation model and verified by real vessel test and observation. The building with a height of 60 m has covered 973,090 m² of sheltered area for Shekou radar. The results can be used not only to analyze the influence of buildings on existing vessel traffic service radar stations but also to provide an important reference for site selection of vessel traffic service radar stations.]]></description>
      <pubDate>Thu, 21 Jan 2021 13:37:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/1711789</guid>
    </item>
  </channel>
</rss>