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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>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Optimal information perturbation for traffic congestion mitigation: Gaussian process regression and optimization</title>
      <link>https://trid.trb.org/View/1932087</link>
      <description><![CDATA[Information perturbation is an information provision strategy which strategically alters the traffic information sent to drivers, aiming to mitigate network congestion caused by selfish routing decisions. Previous works have integrated information perturbation into coordinated routing mechanisms and theoretically proved that the system performance improvement due to information perturbation is more significant than the corresponding average user optimality loss. However, they do not give direct guidance as to which perturbation level should be implemented to manage the competing effects of system performance improvement and user optimality loss most efficiently. Accordingly, the goal of this work is to uncover the optimal perturbation that should be included in the information sent to vehicles under a coordinated routing scheme under some known network condition. The optimal perturbation problem considers the tradeoff between system performance improvement and user optimality loss due to perturbation, while ensuring that no exorbitant individual user optimality loss occurs. The relationships used in the optimization models are obtained through gaussian process regression, which are trained using the output of computer experiments. The authors pay special attention to the input features of these models, which impact the system performance and user optimality loss in their model the most—namely the perturbation, demand, and routing competition levels. The authors model route competition levels through a new parameter called weighted concentration, and present a novel approach for sampling weighted competition values for a single demand level. The authors present several candidate gaussian process specifications which are used in the optimization, including single and multiple output. Finally, the authors demonstrate the merit of their methodology through a sensitivity analysis using the Sioux Falls network as a test case. Here, the authors find that their optimization approach can find robust solutions (in terms of their proximity to local optimums) relatively high rate, with a satisfied solution time.]]></description>
      <pubDate>Mon, 18 Apr 2022 11:57:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/1932087</guid>
    </item>
    <item>
      <title>Running Stability Analysis for Express Wagon with Modified Stochastic Perturbation Method</title>
      <link>https://trid.trb.org/View/1910067</link>
      <description><![CDATA[The design idea of express wagon is to ensure that the car-body has the characteristics of hi-cube capacity and easy loading and unloading which indirect causes the stiffness of car-body is changed with uncertain factors, such as the full sliding side covered and other forms of design, thus the running stability of the vehicle operation is affected and the risk of the transported goods is damaged will be increased. The random dynamic analysis for the express wagon is operated with the railway vehicles random analysis procedure (RVRAP) according to the analysis process firstly, then the uncertain stiffness is described by random variable and the modified stochastic perturbation method is employed to establish a deterministic approach. In this paper, the random variable parameter of side post stiffness for the express wagon is selected and the running stability index at three positions on the underframe are calculated. The result shows that the parameter uncertainty of stiffness of the side post has a greater impact on the vertical running stability than the lateral and ignoring the uncertainty of the parameter will result in a higher stability evaluation result.]]></description>
      <pubDate>Tue, 29 Mar 2022 09:32:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/1910067</guid>
    </item>
    <item>
      <title>Revealing spatiotemporal correlation of urban roads via traffic perturbation simulation</title>
      <link>https://trid.trb.org/View/1892933</link>
      <description><![CDATA[Unbalanced interactions in cities result to a correlation between urban road segments with spatiotemporal heterogeneity. The accurate detection of this spatiotemporal correlation can significantly contribute to traffic congestion prediction and sustainable urban operations. However, the spatiotemporal nonstationarity of the traffic flow causes dynamic uncertainty in road network correlation. Therefore, the authors proposed a novel method to evaluate the spatiotemporal correlation of road networks. First, a dynamic chain propagation model of traffic perturbation was constructed to track the propagation process of traffic response. Then, the time and spatial lag operators were designed based on the perturbation response and utilized to detect the local spatiotemporal correlation of the road network. Finally, a new remote correlation measurement model was proposed by capturing the traffic flow contribution. Experiments demonstrated that the average local correlation of an urban road network is 0.83 in first-order neighborhood segments, which decreases to 0.72 in third-order neighborhood segments with the synchronous increase of space-time lag operators. Moreover, the correlations of downstream segments are on average 11.6% higher than those of upstream segments. These results can provide targeted decision support for preventing the potential spread of traffic congestion, reducing urban air pollution, and promoting sustainable urban development.]]></description>
      <pubDate>Thu, 16 Dec 2021 16:08:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1892933</guid>
    </item>
    <item>
      <title>Active heave compensation of floating wind turbine installation using a catamaran construction vessel</title>
      <link>https://trid.trb.org/View/1744150</link>
      <description><![CDATA[The application of floating wind turbines is limited by the high cost that increases with the water depth. Offshore installation and maintenance continue to consume a high percentage of the project budget. To improve the installation efficiency of the floating offshore wind turbine, a novel concept is proposed by the SFI MOVE project. Several wind turbine superstructure components are preassembled onshore and carried to the installation site by a catamaran construction vessel. Each assembly can then be installed using only one lift, and the concept is less sensitive to weather conditions. In this paper, a control algorithm of the proposed hydraulic active heave compensator system is developed using singular perturbation theory to cancel the relative motion between the spar top and gripped preassembly bottom. Closed-loop stability is proven, and the simulation results show that the installation efficiency is improved with an increase in the acceptable weather conditions.]]></description>
      <pubDate>Mon, 02 Nov 2020 09:27:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1744150</guid>
    </item>
    <item>
      <title>PC–SPSA: Employing Dimensionality Reduction to Limit SPSA Search Noise in DTA Model Calibration</title>
      <link>https://trid.trb.org/View/1696159</link>
      <description><![CDATA[Calibration and validation have long been a significant topic in traffic model development. In fact, when moving to dynamic traffic assignment (DTA) models, the need to dynamically update the demand and supply components creates a considerable burden on the existing calibration algorithms, often rendering them impractical. These calibration approaches are mostly restricted either due to non-linearity or increasing problem dimensionality. Simultaneous perturbation stochastic approximation (SPSA) has been proposed for the DTA model calibration, with encouraging results, for more than a decade. However, it often fails to converge reasonably with the increase in problem size and complexity. In this paper, the authors combine SPSA with principal components analysis (PCA) to form a new algorithm, they call, PC–SPSA. The PCA limits the search area of SPSA within the structural relationships captured from historical estimates in lower dimensions, reducing the problem size and complexity. They formulate the algorithm, demonstrate its operation, and explore its performance using an urban network of Vitoria, Spain. The practical issues that emerge from the scale of different variables and bounding their values are also analyzed through a sensitivity analysis using a non-linear synthetic function.]]></description>
      <pubDate>Fri, 01 May 2020 09:03:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/1696159</guid>
    </item>
    <item>
      <title>Fast Prediction of Disc Brake Squeal Uncertainty Based on Perturbation Concept</title>
      <link>https://trid.trb.org/View/1561055</link>
      <description><![CDATA[It is a worldwide technical difficulty to predict brake squeal uncertainty and its propagation regularity due to key parameters’ randomcity. However, as a widely used stochastic finite element method, Monte Carlo Method costs a large amount of time in calculation. It is very important to establish a fast prediction method for brake squeal uncertainty due to key parameters. In this paper, perturbation concept was applied for disc brake squeal uncertainty prediction. Firstly, a simplified, parameterized finite element model of disc brake was established for complex eigenvalues calculation. Then sensitivity analysis of real parts and frequencies of complex eigenvalues to influence parameters was carried out based on the finite element model. A series of second order perturbation polynomial formulas were fitted from the sensitivity analysis results, which were used for calculation of uncertain complex eigenvalues. The comparison between the results of Monte Carlo method and those of Perturbation method was done from the viewpoints of samples values, statistical values, probability density histograms and probability density curves. The comparison results show that the relative error of perturbation method to Monte Carlo method is less than 5%, and the calculation time is reduced to less than 5%, too. This indicates that the established uncertainty prediction method based on perturbation ideal is a satisfied object oriented brake squeal uncertainty method, which has higher precision and higher efficiency.       ]]></description>
      <pubDate>Fri, 20 Dec 2019 16:17:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1561055</guid>
    </item>
    <item>
      <title>A new method for the structural optimisation of a common type of square wing plate used in the wave glider</title>
      <link>https://trid.trb.org/View/1645937</link>
      <description><![CDATA[The wave glider is widely used in marine engineering. As one of the most crucial components of the wave glider, the wing plate system significantly affects the utilisation efficiency of wave energy. The aim of this research is to optimise the structure of a kind of the square wing plate, which possesses a bad hydrodynamic performance. For the purpose, a new structural optimisation method was developed, in which the optimal sweepback angle and leading edge radius of square wing plate were calculated. Structural dynamic sensitivity analysis and matrix perturbation theory were combined to establish a proper guidance for structural modification, which could avoid blindness during structural modification. Then, dynamics characteristics of the optimised wing plate were investigated based on finite element analysis and experimental modal testing. Finally, the hydrodynamic performance of the optimised wing plate was evaluated. Results show that the newly proposed optimisation method is feasible and effective, and it also can be used for wing plates in other underwater vehicle applications.]]></description>
      <pubDate>Wed, 25 Sep 2019 17:17:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/1645937</guid>
    </item>
    <item>
      <title>How to Play a Disc Brake: A Dissipation-Induced Squeal</title>
      <link>https://trid.trb.org/View/1429607</link>
      <description><![CDATA[The eigenvalues of an elastic body of revolution, rotating about its axis of symmetry, form a ‘spectral mesh’. The nodes of the mesh in the plane ‘frequency’ versus ‘gyroscopic parameter’ correspond to the double eigenfrequencies. With the use of the perturbation theory of multiple eigenvalues, deformation of the spectral mesh caused by dissipative and non-conservative perturbations, originating from the frictional contact, is analytically described. The key role of indefinite damping and non-conservative positional forces in the development of the subcritical flutter instability is clarified. A clear mathematical description is given for the mechanism of excitation of particular modes of rotating structures in frictional contact, such as squealing disc brakes and singing wine glasses.       ]]></description>
      <pubDate>Thu, 28 Feb 2019 09:38:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/1429607</guid>
    </item>
    <item>
      <title>Wider Dissemination of Household Travel Survey Data Using Geographical Perturbation Methods</title>
      <link>https://trid.trb.org/View/1475689</link>
      <description><![CDATA[Historically, concerns regarding disclosure risk have been addressed in travel behavior research through the aggregation of these important and expensive data in order to adequately uphold the confidentiality pledge made between a survey respondent and administrator. Unfortunately, this practice of zonal aggregation compromises the utility of these datasets to researchers requiring a finer spatial representation to better understand the connection between non-motorized travel and the built environment since many of these trips often occur over shorter distances. Thus, there is a great benefit to providing these household travel data as a disaggregate representation. While largely unaddressed in travel behavior research, the negotiation of this barrier centered on minimizing the risk of identity disclosure for a survey respondent and ensuring the possibility of valid geographical analyses has received ample attention in other disciplines, which have sought to address this complication by the application of geographic perturbation methods. In general, a decrease in the potential for a breach of survey respondent confidentiality through the application of a geographic perturbation technique is directly associated with a decrease in the utility of the spatially altered dataset to the researcher. Although this relationship between disclosure risk and data utility has been established, there is no consensus on a single procedure for balancing these central concepts with the intention of aiding the dissemination of these valuable disaggregate data to a wider audience. This report offers an in-depth exploration of this overarching tradeoff by: (1)  Examining the state of the literature with respect to geographic perturbation methods, disclosure risk and compromised data utility. (2) Developing a conceptual framework to guide efforts of geo-perturbation with respect to risk disclosure and data utility. (3) Conducting an empirical application of an innovative methodology that has the potential to permit the dissemination of higher resolution household travel survey data that also protects the confidentiality of the respondent’s household location. (4) Quantifying the concepts of disclosure risk and data utility in this implementation of a geographic perturbation technique in order to improve the understanding of their tradeoff.]]></description>
      <pubDate>Wed, 26 Jul 2017 09:28:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1475689</guid>
    </item>
    <item>
      <title>Ballistic error propagation algorithm for glide trajectory based on perturbation theory</title>
      <link>https://trid.trb.org/View/1471416</link>
      <description><![CDATA[A ballistic error propagation algorithm for glide trajectories of a hypersonic glide vehicle is originally proposed based on the perturbation theory. Perturbation equations that treat perturbations as external inputs and flight state deviations as state variables are established. Based on the reasonable simplification assumptions, the analytic expression of the state transition matrix is deduced and thus the ballistic error propagation model is established. A transposed coordinate frame is introduced to simplify the development of the perturbation equations and the error propagation model. By employing the gravity anomaly as the single perturbation factor, the proposed algorithm is validated and verified by numerical experiments. When compared with the traditional method, the proposed method takes only just a quarter computational costs and restrains the method errors beneath 10% of the total terminal deviations. It is an effort that initially focuses on the error propagation mechanism of the glide trajectory and the proposed model has sufficient precision for the analysis of modeling deviations, thus laying the foundation of correcting the modeling deviations and enhancing the accuracy of vehicle’s flight states.]]></description>
      <pubDate>Mon, 17 Jul 2017 09:33:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/1471416</guid>
    </item>
    <item>
      <title>A new look at the rate of change of energy consumption with respect to journey time on an optimal train journey</title>
      <link>https://trid.trb.org/View/1435523</link>
      <description><![CDATA[The authors present a new derivation of a key formula for the rate of change of energy consumption with respect to journey time on an optimal train journey. They use a standard mathematical model (Albrecht et al., 2015b; Howlett, 2000; Howlett et al., 2009; Khmelnitsky, 2000; Liu and Golovitcher, 2003) to define the problem and show by explicit calculation of switching points that the formula also applies for all basic control subsequences within the optimal strategy on appropriately chosen fixed track segments. The rate of change was initially derived as a known strictly decreasing function of the optimal driving speed in a text edited by  Isayev (1987, Section 14.2, pp 259–260) using an empirical resistance function. An elegant derivation by Liu and Golovitcher (2003, Section 3) with a general resistance function required an underlying assumption that the optimal strategy is unique and that the associated optimal driving speed is a strictly decreasing and continuous function of journey time. An earlier proof of uniqueness (Khmelnitsky, 2000) showed that the optimal driving speed decreases when journey time increases. A subsequent constructive proof (Albrecht et al., 2013a, 2015c) used a local energy minimization principle to find optimal switching points and show explicitly that the optimal driving speed is a strictly decreasing and continuous function of journey time. The authors new derivation of the key formula also uses the local energy minimization principle and depends on the following observations. If no speed limits are imposed the optimal strategy consists of a finite sequence of phases with only five permissible control modes. By considering all basic control subsequences and subdividing the track into suitably chosen fixed segments the authors show that the key formula is valid on each individual segment. The formula is extended to the entire journey by summation. The veracity of the formula is demonstrated with an elementary but realistic example.]]></description>
      <pubDate>Wed, 21 Dec 2016 11:29:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/1435523</guid>
    </item>
    <item>
      <title>Coordinated online in-vehicle routing balancing user optimality and system optimality through information perturbation</title>
      <link>https://trid.trb.org/View/1366599</link>
      <description><![CDATA[The inconsistence between system optimality and user optimality represents one of the key difficulties on network traffic congestion control. The advanced connected vehicle systems, enabling smart vehicles to possess/exchange real-time information and conduct portable computation, provide new opportunities to address this challenge. Motivated by this view, this study proposes a coordinated online in-vehicle routing mechanism with intentional information provision perturbation (CRM-IP), which seeks to shape individual vehicles online routing decisions so that user optimality and system optimality are balanced, by exploiting bounded rationality of the users. The proposed CRM-IP is modeled as a pure strategy atomic routing game, and implemented by a sequentially updating distributed algorithm. The mathematical analysis is conducted to quantify the absolute gain of system optimality corresponding to the loss of user optimality resulting from a given level of the information perturbation in the worst case so that the efficiency of the information perturbation can be evaluated. Furthermore, numerical experiments conducted based on City of Sioux Falls network investigate the average effects of the CRM-IP on system optimality and user optimality under various network traffic conditions, comparing to the CRM developed by Du et al. (in press). The results indicate that the improvement of system optimality and the reduction of individual vehicles’ travel time from the CRM is more significant when the network traffic is under an mild congestion state, such as under the levels of service (LOS’s) C, D, and E, rather than under extremely sparse or congested states, such as under LOS’s A and B, or F. Moreover, higher level of information perturbation benefits system optimality more, but the marginal effect decreases after the perturbation reaching certain level, such as ? = 0.1 in this case study. In addition, a portion of vehicles may sacrifice user optimality due to the information perturbation, but the extent of the sacrifice is not significant, even though it increases with the information perturbation level. Hence, a small information perturbation is recommended to achieve an efficient network traffic control through the CRM-IP. Overall, this study proposes the CRM-IP as an efficient routing mechanism, which has a great potential to guide the routing decisions of individual vehicles so that their collective behavior improve network performance in both system optimality and user optimality.]]></description>
      <pubDate>Fri, 25 Sep 2015 16:28:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/1366599</guid>
    </item>
    <item>
      <title>Sea Surface Effects on Sound Scattering in the Persian Gulf Region Based on Empirical Relations</title>
      <link>https://trid.trb.org/View/1355801</link>
      <description><![CDATA[In this paper, sound scattering from the sea surface in the Persian Gulf region is investigated. Chapman-Harris and Ogden-Erskine empirical relations coupled with perturbation theory are implemented. Based on the Ogden and Erskine’s experiments, sound scattering from the sea surface has three different regimes in which two mechanisms of surface roughness and subsurface bubble clouds are involved. Ogden-Erskine’s scattering relation which consists of perturbation theory and Chapman-Harris’s scattering terms are verified by the experimental data of Critical Sea Tests 7. Subsequently, wind speed in the Persian Gulf is provided based on three data bases of Arzanah station, ERA40, and PERGOS. Accordingly, surface scattering strength in the Persian Gulf region is calculated at different grazing angles, frequencies and provided wind speeds. Based on the resulted values of scattering strength, scattered intensity from the sea surface is also studied. These studies indicate that both scattering strength and scattered intensity generally increase as grazing angle, frequency and wind speed increase.]]></description>
      <pubDate>Fri, 26 Jun 2015 17:12:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1355801</guid>
    </item>
    <item>
      <title>Scattering of Oblique Surface Waves by the Edge of Small Deformation on a Porous Ocean Bed</title>
      <link>https://trid.trb.org/View/1355794</link>
      <description><![CDATA[The scattering of oblique incident surface waves by the edge of a small cylindrical deformation on a porous bed in an ocean of finite depth, is investigated here within the framework of linearized water wave theory. Using perturbation analysis, the corresponding problem governed by modified Helmholtz equation is reduced to a boundary value problem for the first-order correction of the potential function. The first-order potential and, hence, the reflection and transmission coefficients are obtained by a method based on Green's integral theorem with the introduction of appropriate Green’s function. Consideration of a patch of sinusoidal ripples shows that when the quotient of twice the component of the incident field wave number along x-direction and the ripple wave number approaches one, the theory predicts a resonant interaction between the bed and the free-surface, and the reflection coefficient becomes a multiple of the number of ripples. Again, for small angles of incidence, the reflected energy is more as compared to the other angles of incidence. It is also observed that the reflected energy is somewhat sensitive to the changes in the porosity of the ocean bed. From the derived results, the solutions for problems with impermeable ocean bed can be obtained as particular cases.]]></description>
      <pubDate>Fri, 26 Jun 2015 17:12:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/1355794</guid>
    </item>
    <item>
      <title>A Modular Approach to Model Oscillating Control Surfaces Using Navier Stokes Equations</title>
      <link>https://trid.trb.org/View/1324778</link>
      <description><![CDATA[The use of active controls for rotorcraft is becoming more important for modern aerospace configurations. Efforts to reduce the vibrations of helicopter blades with use of active-controls are in progress. Modeling oscillating control surfaces using the linear aerodynamics theory is well established. However, higher-fidelity methods are needed to account for nonlinear effects, such as those that occur in transonic flow. The aeroelastic responses of a wing with an oscillating control surface, computed using the transonic small perturbation (TSP) theory, have been shown to cause important transonic flow effects such as a reversal of control surface effectiveness that occurs as the shock wave crosses the hinge line. In order to account for flow complexities such as blade-vortex interactions of rotor blades, higher-fidelity methods based on the Navier-Stokes equations are used.]]></description>
      <pubDate>Tue, 21 Oct 2014 14:09:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1324778</guid>
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