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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" />
    <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>Frequency-Variant Electronic Capacitor to Simultaneously Reduce Low-Frequency DC-Link Voltage Ripple and Improve Current THD of Grid-Connected Power Converters</title>
      <link>https://trid.trb.org/View/2315266</link>
      <description><![CDATA[Electronic capacitor (EC) is a circuit typically aimed to replace (in part or entirely) the bulk DC-link capacitor of a grid-interfacing power converter in a plug-and-play manner. EC is realized by a bidirectional dc-dc converter terminated with small auxiliary capacitor. The converter is controlled such that its DC-link side terminals mimic the behavior of a capacitor with much higher constant capacitance. In this article, a modification of the classical EC control structure is proposed, imposing the DC-link side terminals to emulate a frequency-variant capacitor rather than a constant one. The proposed algorithm allows achieving simultaneous reduction of both DC-link voltage ripple and grid-side current total harmonic distortion (THD) compared to ones attained by classical solutions, thus improving the tradeoff between DC-link voltage dynamics and ac-side current quality inevitably present in any grid-connected power converter. The proposed methodology is well supported by experiments.]]></description>
      <pubDate>Wed, 24 Jan 2024 16:55:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/2315266</guid>
    </item>
    <item>
      <title>A Multi-Frequency Harmonic Generator Based on the Voltage Source Converter for Traction Power Load Impedance Identification</title>
      <link>https://trid.trb.org/View/2313986</link>
      <description><![CDATA[As a typical single-phase electric power system, high-speed railway system gradually absorbs the more single-phase electric traction vehicles (trains) with its rapid development. Traction power load (TPL) is the electrical part of the train. The incompatible interactions between traction power network (TPN) and TPL generally cause the serious wideband oscillations, fortunately, which can be readily analyzed with the identified wideband impedances. As for impedance identification, the multi-frequency harmonic generator is of great significance to rapidly excite the desired responses for impedance calculation, however which is vacant for the single-phase TPL, and needs a further study. Aiming at it, this article proposes a multi-frequency harmonic generator based on the transformer-less cascaded H-bridge (CHB) converters with floating DC capacitors. In detail, its corresponding multi-frequency harmonic control loop is derived by the internal model principle (IMP), and the inserted notch filter and repetitive controller can strengthen the multi-frequency harmonic output performance. Finally, results of simulation and corresponding down-scale physical experiment can well verify that the proposed harmonic generator can output multiple harmonics simultaneously with high purity and well-behaved tracking performance.]]></description>
      <pubDate>Wed, 27 Dec 2023 10:28:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2313986</guid>
    </item>
    <item>
      <title>Modelling comparison for harmonic dynamic characteristics of a silicone-oil-filled rubber isolator and response analysis of a single DOF system</title>
      <link>https://trid.trb.org/View/2248929</link>
      <description><![CDATA[In practical engineering applications, especially for earthmoving equipment, silicone-oil-filled rubber isolators have shown better vibration isolation performance than common rubber isolators. The silicone oil path presents complex dynamic properties. This paper mainly studies the dynamic characteristics of the isolator by modelling in different ways. Four viscoelastic models, namely Maxwell, fractional Maxwell, Zener and fractional Zener models, are established, respectively. The dynamic stiffness, storage stiffness, loss stiffness and loss factor are calculated, respectively. The results show that the fractional derivative models are more consistent with the experimental results. Moreover, the fractional Zener model can make up for lack of stiffness of the fractional Maxwell model. Finally, harmonic responses of a single degree-of-freedom (DOF) vibration isolation system are examined, where the fractional Zener model is used. The dynamic magnification factor, phase angle and force transmissibility are respectively calculated in the frequency domain and the effects of the design parameters are discussed.]]></description>
      <pubDate>Mon, 23 Oct 2023 15:08:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/2248929</guid>
    </item>
    <item>
      <title>Harmonic Stability Analysis of Single-Phase Converters in Electric Multiple Units Based on an Impedance Model with Harmonic Linearization</title>
      <link>https://trid.trb.org/View/2222499</link>
      <description><![CDATA[Low-frequency oscillation, harmonic oscillation and harmonic instability issues in railway vehicle-grid systems pose challenges to the system stability and safe operation. Previous studies constructed the linear time-invariant impedance model of vehicle-grid system, which ignored the internal frequency coupling and loss of model accuracy. To fill this gap, the impedance modelling method based on the harmonic linearisation method of the vehicle-grid system is proposed. The derived model provides a clear physical insight into the harmonic coupling relations between ac and dc variables and improves the model accuracy. Then, a systematic analysis of harmonic stability in the railway vehicle-grid system is analysed based on the proposed model. The electrical and control parameters on system stability at the frequencies above and below the fundamental frequency are summarised. The mechanisms of these oscillation issues in railway vehicle-grid systems are then discussed. Finally, the model accuracy and stability analysis results are verified by the frequency scan method and hardware-in-the-loop results.]]></description>
      <pubDate>Thu, 31 Aug 2023 10:11:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2222499</guid>
    </item>
    <item>
      <title>Excitation force on a pump-jet propeller: The effect of the blade number</title>
      <link>https://trid.trb.org/View/2212346</link>
      <description><![CDATA[This study investigates the influence of blade number on the propulsion performance and excitation force of pump-jet propellers (PJPs) using computational fluid dynamics. The primary objective is to determine the optimal blade number arrangement for reducing the excitation force of PJPs while operating behind a submarine. The numerical simulation method used is validated, employing the Reynolds-averaged Navier–Stokes method based on the Shear Stress Transport turbulence model to solve the turbulent flow problem, and the equation is discretized using the finite volume method. By comparing and analyzing the spectrum, it was found that the blade number would affect the unsteady force of single blades in six aspects, and when it impacts the Key Frequency,the amplitude of the excitation force varies dramatically. Through harmonic analysis and strip analysis, this study uncovers the influential mechanism of the blade number on excitation force. Additionally, a unique wake mechanism arising from the combined effect of stator and rudder is discovered by examining various number of stator blade and rudder. Ultimately, the optimal blade number of stator-rotor configurations is found to be 15 and 10, respectively. This study has implications for the design of PJPs with low excitation.]]></description>
      <pubDate>Tue, 18 Jul 2023 15:14:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2212346</guid>
    </item>
    <item>
      <title>Harmonic analysis of a marine shaft-bearing suspension system and its semi-active control with PID strategy</title>
      <link>https://trid.trb.org/View/2170110</link>
      <description><![CDATA[A stable operating state of the marine shaft-bearing system is essential to minimize the vibration level and improve the transmission efficiency of the ship power system. A semi-active control with PID strategy is proposed through an adjustable damping magnetorheological shock absorber and the combination of the electromagnetic actuator based on the existing suspension system. The harmonic response of the system is calculated through transfer function with various suspension stiffness and damping. The controlled behaviors include suspension travel, soleplate deflection, sprung shaft and unsprung bearing, are obtained through Matlab/Simulink. The proposed controller is demonstrated to be applicable through robustness analysis by comparing with passive and LQR control based on the disturbance of pulse width modulation. The controlled behaviors with minor stiffness and significant damping are noticed to be more satisfied through the influence comparison of suspension parameters. The controlled performance includes reduction rate, overshoot rate and setting time with various values of control factors are discussed to prove the suitability. The semi-active control for the transverse vibration of the marine shaft-bearing system is thus realized based on the adjustment of control parameters.]]></description>
      <pubDate>Tue, 20 Jun 2023 10:09:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/2170110</guid>
    </item>
    <item>
      <title>Composite fault diagnosis method of EMU traction motor speed sensor considering harmonic interference</title>
      <link>https://trid.trb.org/View/2087509</link>
      <description><![CDATA[In order to improve the accuracy of the fault diagnosis of the motor speed sensor and reduce the time-consuming, this paper proposes a composite fault diagnosis method for the traction motor speed sensor of the electric multiple unit (EMU) considering harmonic interference. This paper takes the traction system of the CRH2 EMU as the research object, calculates the multi-dimensional fuzzy harmonic closeness of the speed sensor fault signal and the normal signal, and extracts the harmonic interference characteristics. Experimental results show that the diagnostic accuracy of the proposed method is high, the time-consuming is stable below 150 ms, and the packet loss rate is stable at about 2%, which is significantly better than other comparative systems. The reliability of the proposed method is verified.]]></description>
      <pubDate>Wed, 22 Feb 2023 09:41:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2087509</guid>
    </item>
    <item>
      <title>Evolution of complex modulus and higher harmonics of stress response of asphalt concrete in strain-controlled four-point beam fatigue tests</title>
      <link>https://trid.trb.org/View/2078121</link>
      <description><![CDATA[The modulus of asphalt concrete that is conventionally obtained from large amplitude oscillations (LAOs) in fatigue tests cannot be considered a material property since the response changes from cycle to cycle. It is necessary to determine how viscoelastic properties vary with the extent of damage, and they cannot be obtained from LAOs without making specific constitutive assumptions. Moreover, the higher harmonics of the stress response can be used to quantify the distortion of the stress waveform and, therefore, the point of failure in fatigue tests. This should also be explored further. With these as the objectives, strain-controlled four-point bending (4PB) tests were conducted in this study with the LAOs regularly interrupted to apply a few cycles of small amplitude oscillations (SAOs). The stress response from both SAOs and LAOs were subjected to Fourier analysis. The fundamental harmonic was used to define the apparent storage and loss moduli, and the moduli from the SAOs and LAOs were compared with each other. The ratio of the amplitude of the third harmonic to the first harmonic was found to sharply increase after a certain point in the test. This was used to define a new failure criterion for 4PB fatigue tests.]]></description>
      <pubDate>Tue, 13 Dec 2022 17:35:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2078121</guid>
    </item>
    <item>
      <title>Stator vibration analysis of in-wheel motor for electric vehicle based on harmonic response analysis method</title>
      <link>https://trid.trb.org/View/2026065</link>
      <description><![CDATA[In order to effectively reduce the vibration and noise of in-wheel motor for electric vehicle, the radial electromagnetic force wave of in-wheel motor under load is decomposed by Fourier transform, and the results are obtained. The radial electromagnetic force wave has large harmonic amplitude and wide frequency distribution. Finally, the free mode and harmonic response of three different stator configurations are analysed. The results show that: under the action of the radial force wave, the maximum deformation of the stator without cooling channel is 6.639e-5 mm, the maximum deformation of the stator with radial cooling channel is 5.8224e-5 mm, and the maximum deformation of the stator with axial cooling channel is 6.864e-5 mm. The deformation is very small, and there will be no friction and collision between the stator and the rotor during the operation of the in-wheel motor.]]></description>
      <pubDate>Mon, 28 Nov 2022 10:56:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/2026065</guid>
    </item>
    <item>
      <title>Performance Comparison of Harmonic Oscillations of a Vehicle Suspension in a Digital PID Controller Using Classic and Aström Design Methodologies Mapped by Tustin and Souza-Tredinnick Rules</title>
      <link>https://trid.trb.org/View/1810220</link>
      <description><![CDATA[The authors propose in this work, some numerical experiments aiming at the comparison of the performance between two design methods of digital PID (Proportional + Integral + Derivative) control, using two kinds of digital redesign mapping techniques, of a benchmark damped harmonic oscillator as vehicle suspension suffering the fading effect of aliasing due the increasing of the sampling-period of A/D and D/A converters. With a short-pulse input the authors have used as comparison parameter in transient responses the maximum overshoot and a chaotic behavior is reported for some cases and the best methodology and mapping is indicated as well as better results are reported with design using the Souza-Tredinnick rule instead of the Tustin rule.]]></description>
      <pubDate>Mon, 17 Oct 2022 13:38:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1810220</guid>
    </item>
    <item>
      <title>Vibration noise suppression algorithm of permanent magnet synchronous motor for new energy vehicles</title>
      <link>https://trid.trb.org/View/1991508</link>
      <description><![CDATA[Taking the permanent magnet synchronous motor (PMSM) for new energy vehicles as the research object, the causes and mechanisms of electromagnetic vibro-acoustics of fractional-slot PMSM are analyzed and summarized. According to the analysis results, a novel control strategy-hysteresis current tracking technology is proposed to suppress the torque ripple and reduce electromagnetic noise. On the basis of the above, the band-stop filter method is introduced to quantitatively analyze the influence of controller parameters. The finite element method is used to study the relationship among the initial phase angle, frequency and amplitude of the electromagnetic force and the injected harmonic voltage of the stator. The analysis and experimental results show that the error rate curve of the proposed algorithm is closer to the curve without phase noise when the phase noise line width is small. The vibro-acoustics can be effectively reduced by injecting the corresponding harmonic voltage with the optimization results.]]></description>
      <pubDate>Mon, 26 Sep 2022 09:10:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1991508</guid>
    </item>
    <item>
      <title>Coupled Magnetic Circuit-Based Design of an IPMSM for Reduction of Circulating Currents in Asymmetrical Star–Delta Windings</title>
      <link>https://trid.trb.org/View/1945561</link>
      <description><![CDATA[Combined star (Y)–delta (Δ) windings suffer from undesirable circulating currents resulting in increased winding losses and saturation, leading to demagnetization in permanent magnet synchronous machines (PMSMs). The main causes for these currents are the induced voltage harmonics from the winding configuration and rotor saliency. Thus, this article presents a novel coupled winding function and magnetic circuit model to accurately model the winding harmonics and rotor saliency in Y – Δ wound PMSMs. Unlike existing winding harmonic analysis methods, such as winding factor approach and star of slots, the developed winding function incorporates the effect of winding asymmetry. Although asymmetrical Y – Δ windings suffer from higher circulating currents, such configurations result in higher torque, efficiency, and reduced torque ripple when compared to conventional symmetrical windings. Therefore, using the proposed magnetic circuit model incorporating rotor saliency, an interior PMSM (IPMSM) rotor structure is developed for reduced circulating currents without compromising the traction performance. Experimental results are presented to highlight reduced circulating currents in terms of induced voltage harmonics and machine saliency and to illustrate its effect on the machine’s superior traction performance capability such as improved rated torque, efficiency, and reduced torque ripple, winding losses, and magnetic saturation.]]></description>
      <pubDate>Tue, 26 Jul 2022 13:21:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/1945561</guid>
    </item>
    <item>
      <title>Effects of Line and Load Conditions on TRU and ATRU Input Current Harmonics</title>
      <link>https://trid.trb.org/View/1822381</link>
      <description><![CDATA[This paper presents modeling and analysis of the harmonic performance of multi-pulse Transformer-Rectifier Units (TRU) and Autotransformer-Rectifier Units (ATRU) under different non-ideal operation conditions. Other than numerical simulations, the paper presents an analytical method to quantify and study the effects by describing the operation of the converters by the so-called mapping functions. Double-Fourier series method is applied to determine the Fourier representation of the mapping functions. Based on the analytical models in the frequency domain, the effects of harmonic voltage and load current harmonics are theoretically investigated.]]></description>
      <pubDate>Mon, 25 Jul 2022 17:34:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/1822381</guid>
    </item>
    <item>
      <title>Study of Boosted Toothed Biased Flux Permanent Magnet Motors</title>
      <link>https://trid.trb.org/View/1945529</link>
      <description><![CDATA[In this article, three new toothed biased flux permanent magnet (PM) motors are introduced and studied, each of which has a specific arrangement of excitation (dc field/PM) and flux path (series/parallel). This results in three main structures, namely, hybrid excited toothed slot-PM (HETSPM), toothed biased flux PM (TBFPM) with series flux path, and, finally, toothed biased flux slot PM (TBFSPM) with hybrid flux path. The TBFSPM structure has improved the average torque, torque ripple, and efficiency compared to other stator-PM motors. The HETSPM structure has improved the average torque per PM, and the TBFPM structure features a very low-torque ripple profile compared to other stator-PM motors. All the topologies have shown a good PM demagnetization resistance and lower PM loss compared to other structures. Moreover, a new Carter’s coefficient is introduced to increase the accuracy of harmonic analysis for split-tooth structures by modeling the nonlinear effect of fringing flux with a new transition function, which has increased the accuracy by 20% compared to the traditional approach. The theoretical analyses have been checked by the 2-D finite element method (FEM), and the TBFSPM structure is prototyped and tested to validate the simulation analyses.]]></description>
      <pubDate>Thu, 21 Jul 2022 11:32:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/1945529</guid>
    </item>
    <item>
      <title>Analytical Model of Electromagnetic Performance for Permanent-Magnet Vernier Machines Using Nonlinear Exact Conformal Model</title>
      <link>https://trid.trb.org/View/1945489</link>
      <description><![CDATA[This article investigates the air-gap field distribution of the permanent-magnet Vernier machine (PMVM) using a nonlinear exact conformal model (NECM) to account for slotting effect, flux modulation effect, and iron nonlinearity. The exact conformal model (ECM) based on the region of one-slot and one-flux-modulation-pole (OSECM) are introduced to show the effectiveness of the linear analytical model for PMVM. It can keep high calculation accuracy and significantly reduce the computational burden. Then, the NECM is developed from OSECM by introducing the equivalent saturation current into the air region and coil region. The lumped parameter magnetic circuit model (LPMCM) model is used to obtain the magnetic potential of the iron region and therefore calculate the equivalent saturation current. The NECM which combines LPMCM and OSECM can essentially improve the accuracy of the linear analytical model. The harmonic analysis of the air-gap field is performed to theoretically explain the component of electromagnetic torque. Both finite element model (FEM) simulation and test results are presented to validate the NECM.]]></description>
      <pubDate>Mon, 27 Jun 2022 09:00:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/1945489</guid>
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