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Lebel, David. "Statistical inverse problem in nonlinear high-speed train dynamics." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC2189/document.
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Ce travail de thèse traite du développement d'une méthode de télédiagnostique de l'état de santé des suspensions des trains à grande vitesse à partir de mesures de la réponse dynamique du train en circulation par des accéléromètres embarqués. Un train en circulation est un système dynamique dont l'excitation provient des irrégularités de la géométrie de la voie ferrée. Ses éléments de suspension jouent un rôle fondamental de sécurité et de confort. La réponse dynamique du train étant dépendante des caractéristiques mécaniques des éléments de suspension, il est possible d'obtenir en inverse des informations sur l'état de ces éléments à partir de mesures accélérométriques embarquées. Connaître l'état de santé réel des suspensions permettrait d'améliorer la maintenance des trains. D’un point de vue mathématique, la méthode de télédiagnostique proposée consiste à résoudre un problème statistique inverse. Elle s'appuie sur un modèle numérique de dynamique ferroviaire et prend en compte l'incertitude de modèle ainsi que les erreurs de mesures. Les paramètres mécaniques associés aux éléments de suspension sont identifiés par calibration Bayésienne à partir de mesures simultanées des entrées (les irrégularités de la géométrie de la voie) et sorties (la réponse dynamique du train) du système. La calibration Bayésienne classique implique le calcul de la fonction de vraisemblance à partir du modèle stochastique de réponse et des données expérimentales. Le modèle numérique étant numériquement coûteux d'une part, ses entrées et sorties étant fonctionnelles d'autre part, une méthode de calibration Bayésienne originale est proposée. Elle utilise un métamodèle par processus Gaussien de la fonction de vraisemblance. Cette thèse présente comment un métamodèle aléatoire peut être utilisé pour estimer la loi de probabilité des paramètres du modèle. La méthode proposée permet la prise en compte du nouveau type d'incertitude induit par l'utilisation d'un métamodèle. Cette prise en compte est nécessaire pour une estimation correcte de la précision de la calibration. La nouvelle méthode de calibration Bayésienne a été testée sur le cas applicatif ferroviaire, et a produit des résultats concluants. La validation a été faite par expériences numériques. Par ailleurs, l'évolution à long terme des paramètres mécaniques de suspensions a été étudiée à partir de mesures réelles de la réponse dynamique du trainThe work presented here deals with the development of a health-state monitoring method for high-speed train suspensions using in-service measurements of the train dynamical response by embedded acceleration sensors. A rolling train is a dynamical system excited by the track-geometry irregularities. The suspension elements play a key role for the ride safety and comfort. The train dynamical response being dependent on the suspensions mechanical characteristics, information about the suspensions state can be inferred from acceleration measurements in the train by embedded sensors. This information about the actual suspensions state would allow for providing a more efficient train maintenance. Mathematically, the proposed monitoring solution consists in solving a statistical inverse problem. It is based on a train-dynamics computational model, and takes into account the model uncertainty and the measurement errors. A Bayesian calibration approach is adopted to identify the probability distribution of the mechanical parameters of the suspension elements from joint measurements of the system input (the track-geometry irregularities) and output (the train dynamical response).Classical Bayesian calibration implies the computation of the likelihood function using the stochastic model of the system output and experimental data. To cope with the fact that each run of the computational model is numerically expensive, and because of the functional nature of the system input and output, a novel Bayesian calibration method using a Gaussian-process surrogate model of the likelihood function is proposed. This thesis presents how such a random surrogate model can be used to estimate the probability distribution of the model parameters. The proposed method allows for taking into account the new type of uncertainty induced by the use of a surrogate model, which is necessary to correctly assess the calibration accuracy. The novel Bayesian calibration method has been tested on the railway application and has achieved conclusive results. Numerical experiments were used for validation. The long-term evolution of the suspension mechanical parameters has been studied using actual measurements of the train dynamical response
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Matos, Sánchez David, and Maša Nikolic. "Comparison of ballasted and ballastless bridges for high speed trains." Thesis, KTH, Bro- och stålbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-188524.
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The purpose of the project is to investigate the difference in performance between ballasted and ballastless railway bridges dedicated to high speed trains by taking into account both static and dynamic requirements. The main questions are: a) whether choosing a ballastless bridge results in a more slender section due to the lower self-weight b) if the design of bridges for high speed trains is governed by the static or by the dynamic requirements. The method followed was to first make a complete static design of a ballasted and a ballastless bridge, and then subject them to a 2D dynamic analyses in order to see if the cross section dimensions must be changed. Some of the bridges required a more thorough dynamic analyses, and for these, a 3D model was developed. The analysed bridge is a simply supported beam with a T section carrying one track. Some variations were also considered, namely a simply supported bridge with a double T section carrying two tracks, as well as a single track bridge in two spans. It was found that all of the analysed bridges are somewhat more slender for the ballastless alternative, and require a 10 -30% less reinforcement. Simply supported bridges carrying one track are governed by the dynamic requirements; the bridges in two spans are for shorter spans governed by the statics and for longer spans by the dynamics. Bridges in double T fulfilled all the requirements according to the 2D analyses, but were found to be greatly affected by the 3 dimensional effects and failed to satisfy the criteria when these were taken into account. Finally, the optimal design according to these analyses is a ballastless bridge in a simple T section. If the bridge constructed should carry two tracks, then it should be constructed as two T beams that are not connected to one another in order to avoid the unfavourable 3D effects.
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Johansson, Christoffer. "Simplified dynamic analysis of railway bridges under high-speed trains." Licentiate thesis, KTH, Bro- och stålbyggnad, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122436.
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The world-wide development of new high-speed rail lines has led to more stringent design requirements for railway bridges. This is mainly due to the fact that a train at high speeds can cause resonance in the bridge superstructure. In order to avoid problems of this kind, it has become essential to perform dynamic simulations, which are usually carried out in a time consuming finite element program. The main reason for not using an analytical solution is that this type of solution only exists for simple bridges, e.g., simply supported bridges. The aim of this thesis, is therefore the development of a simplified analytical model for preliminary dynamic analyses of railway bridges. The model is then used in several studies, both parametric and probabilistic ones, to determine the dynamic response of various railway bridges under moving loads. Special attention is paid to acceleration levels in the bridge superstructure, because previous studies have shown that these are often decisive. In the design, both the model and the numerical simulations can be used with considerable effectiveness to help engineers to define their structural systems. All bridges, throughout this thesis, have been modelled with elastically supported multi-span Bernoulli-Euler beams. The amount of dissipated energy is modelled using modal damping. The train load is modelled by concentrated loads, which implies that the vehicle-bridge interaction is not considered. A model with these characteristics can be used to analyse simply supported concrete bridges as well as multi-span steel bridges. Another advantage of the proposed method is that the solution is exact, because the equation of motion has been solved using a Laplace transform. A lot of effort has been made to have a model both as simple as possible and flexible enough to be able to study a wide variety of structures. The results of the case studies have shown that concrete bridges are more suitable than steel and composite bridges for use in the new high-speed lines. The simulations have also shown that short-span railway bridges have problems in meeting the design requirements. This confirms the high acceleration levels that were recorded in France, just after the inauguration of the new high-speed line between Lyon and Paris, on several short-span bridges. Furthermore, it was found that a multi-span bridge has a reduction in its dynamic response of up to 60 % compared to a similar simply supported bridge.Utbyggnaden av nya höghastighetsbanor i världen har resulterat i striktare krav vid dimensionering av järnvägsbroar. Orsaken är främst att tåg vid höga hastigheter kan orsaka resonans i brons överbyggnad. För att kontrollera dessa effekter krävs omfattande dynamiska simuleringar, vilket ofta utförs med tidskrävande FE-analyser. Med analytiska metoder kan beräkningstiden minskas dramatiskt, dessa är dock ofta begränsade till enkla elementarfall, t.ex. fritt upplagda balkar. Syftet med föreliggande avhandling är att utveckla flexibla hjälpmedel för dynamiska kontroller av järnvägsbroar. Avhandlingen fokuserar på accelerationer i brons överbyggnad eftersom tidigare studier har visat att det är den som ofta är dimensionerande. Utöver detta görs det också ett flertal fallstudier och probabilistiska analyser. Ett stort fokus i arbetet har varit att modellen ska vara tillräckligt flexibel för att kunna analysera olika brotyper, samtidigt som mängden indata är begränsad. Följaktligen består modellen av en serie visköst dämpade Bernoulli-Euler balkar som vilar på elastiska upplag. Tåglasten beskrivs med rörliga punktlaster som appliceras direkt på brons överbyggnad utan att interaktion mellan tåg-spår-bro beaktas. Med dessa egenskaper kan modellen användas till att analysera alltifrån fritt upplagda betongbalkbroar till kontinuerliga samverkansbroar. En annan fördel med den föreslagna modellen är att lösningen är exakt eftersom rörelseekvationen har lösts med en Laplacetransform. Resultaten från fallstudierna visar att betongbroar har lägre dynamisk respons om man jämför med stål- och samverkansbroar. Simuleringarna bekräftar också resultat från tidigare studier som visar att broar med korta spann har svårt att uppfylla accelerationskravet. Detta är något som man också har erfarit i Frankrike, där man efter invigningen av höghastighetslinjen mellan Lyon och Paris uppmätte höga accelerationer hos ett flertal korta broar. Vidare visar också analyserna att en kontinuerlig balkbro har upp till 60 % lägre accelerationer jämfört med om samma bro hade utförts som fritt upplagd.
QC 20130529
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Björklund, Lena. "Dynamic Analysis of a Railway Bridge subjected to High Speed Trains." Thesis, KTH, Bro- och stålbyggnad, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-36794.
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Thomas, Jossian, and Barenys Assís Arañó. "Evaluation of 3D dynamic effects induced by high-speed trains on double-track slab bridges." Thesis, KTH, Bro- och stålbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-188850.
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In addition to a static design, a dynamic analysis has to be performed for bridges for which the maximum permissible train speed exceeds 200 km/h. This analysis requires a lot of computing time, for this reason Svedholm and Andersson (2016) have developed a simple tool describing the relationship between the first eigenfrequency of the bridge, the span length and the minimum mass to fulfill the regulation specified in EN-1990. However, these diagrams are based on 2D beam models in which the 3D dynamic effects are not considered. An evaluation of the torsional modes has been performed by analyzing parametrized 3D bridge models, in order to obtain design diagrams including these effects. To do so, a frequency domain analysis has been implemented, based on a steadystate step previously performed in a FEM software. This approach provides a fast way to solve the equation of motion due to the Fourier transform properties, and allows applying several load configurations which are convenient for a parametric study. From this analysis it can be concluded that the thickness to fulfill the demands is larger for 3D models than for 2D. On one hand, contribution of torsional modes of vibration is more significant for the shortest span length, and on the other hand shear-lag effects lead to a reduction of the total resisting bending section.
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Lewandowski, David. "Experimental and Modeled Effects of Camshaft Manufacturing Errors on the Dynamics of High Speed Valve Trains." NCSU, 1998. http://www.lib.ncsu.edu/theses/available/etd-19981029-101808.
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AbstractLEWANDOWSKI, DAVID JOHN Experimental and Modeled Effects of CamshaftManufacturing Errors on the Dynamics of High Speed Valve Trains. (Under thedirection of Dr. Joseph W. David)The idea of harnessing combustion to perform mechanical work is by no means anew one. The internal combustion engine, as we know it today, has its origins in the lastcentury, however the idea for controlling combustion to perform mechanical work datesback to the Renaissance. Even with the advent of alternative sources of power forcommerce and personal applications, the internal combustion engine represents a largeportion of the power generation available in this country.There are numerous types of internal combustion engines, each with a variety ofsubsystems. While all of these types and corresponding subsystems are equally important,this investigation is focused on the valve train dynamics of a pushrod type internalcombustion engine. Operating this type of engine at too high of an engine speed usuallycauses dynamic malfunctions such as spring surge, lifter/cam pair separation, valvebounce, etc. in the valve train. Although the interaction of each of the valve traincomponents contributes to the limit speed, the shape of the cam plays a critical role.Therefore, this investigation will look at how small changes in the cam profile due tomanufacturing errors change the dynamics of a valve train in a pushrod type engine.Automotive cams can be manufactured as copied or original parts. Copied partsare typically produced on a rocker type cam grinder and the original parts are produced on a computer numerical control grinder. Therefore, various errors associated with thesemanufacturing techniques are studied herein.Installing cams with profile errors in an engine may result in the dynamicmalfunction of its valve train. In order to study the effect of these profile errors, some ofthe error cam profiles that were predicted for the rocker grinder were manufactured andtested in an actual valve train. In addition, the effects of error cam profiles wereinvestigated by using an existing valve train simulation model. It was found by bothexperimentation and simulation that camshaft errors on the order of typical shoptolerances had little impact on the dynamics of high speed valve trains.
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Diedrichs, Ben. "Studies of Two Aerodynamic Effects on High-Speed Trains : Crosswind Stability and Discomforting Car Body Vibrations Inside Tunnels." Doctoral thesis, Stockholm : School of engineering sciences, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4174.
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Lind, Östlund Johan. "Dynamic soil-structure interaction of simply supported high-speed railway bridges." Licentiate thesis, KTH, Bro- och stålbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279651.
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Research performed on the subject of dynamic soil-structure interaction (SS) concerning railway bridges is presented in this thesis with the focus on simply supported railway bridges supported by shallow foundations in soil strata on bedrock. The research aims to obtain insight into the SSI of high-speed railway bridges and to provide recommendations on how to model the soil-bridge system from a design perspective. A three-dimensional (3D) simply supported soil-bridge model was first developed and the effects from model assumptions made on the soil-foundation system was evaluated in a 3D setting (paper I). The soil-foundation system was then refined and a model assumptions study was performed in order to evaluate the effects of model assumptions on impedance functions, including the influence of the permanent load acting on the soil-foundation system (paper II). Finally, a study of the assembled soil-bridge system was performed in an extensive parametric study including a set of 2D bridge models in combination with a set of shallow foundations in soil strata on bedrock (paper III). A supplementary section related to paper III was also added in this thesis, showing the effects of the substructure mass. The model assumptions made when creating the soil-foundation model and the soil-bridge model can be very important and must be made with care. The permanent load acting on the soil-foundation systems of shallow foundations may alter the impedance functions significantly. The substructure mass may alter the behavior of the soil-bridge system depending on its magnitude, and neglecting it gives inaccurate results. The 3D effects of SSI do not cause high vibrations due to modes other than the first bending mode, and assuming a 2D bridge model is generally acceptable. The effects of SSI on the soil-bridge systems with shallow soil strata are largely dependent on the ratio between the natural frequency of the bridge and the fundamental frequency of the soil. Depending on the value of this ratio, the effect of including SSI in bridge models may contribute to the bridge obtaining a negligible, conservative, or non-conservative response, as compared to the bridge with the assumption of non-flexible supports.Forskning i syfte att utröna effekten av dynamisk jord–struktur-interaktion (SSI)på järnvägsbroar presenteras i denna avhandling med huvudfokus på fritt upplagdabroar med stöd av plattgrundlagda fundament i jordar på fast berggrund. Forsknin-gen syftar till att ge förståelse för interaktionen mellan jord och järnvägsbroar samtatt ge rekommendationer på hur systemet kan modelleras ur ett designperspektiv.En tredimensionell (3D) fritt upplagd jord–bromodell utvecklades först och effek-terna av modellantaganden gjorda på jord–grundläggningssystemet utvärderadesi en 3D miljö (artikel I). Jord–grundläggningssystemet förfinades och en studiegenomfördes för att utvärdera effekterna av modellantaganden på impedansfunk-tioner, inklusive påverkan av den permanenta belastningen som verkar på jord–grundläggningssystemet (artikel II). Slutligen utfördes en omfattande parametriskstudie av det sammansatta jord–brosystemet där en uppsättning tvådimensionella(2D) bromodeller kombinerades med en uppsättning jordar (artikel III). Ett kom-pletterande avsnitt relaterat till artikel III lades till i denna avhandling som visareffekterna av massan av underbyggnaden på jord–brosystemet.De modellantaganden som görs vid skapandet av jord–grundläggningsmodeller ochjord–bromodeller kan vara mycket viktiga och bör utföras med varsamhet. Den per-manenta belastningen som verkar på jord–grundläggningssystemet kan väsentligtförändra impedansfunktionerna. Massan av underbyggnaden kan vidare ändra re-sponsen i jord–brosystemet, beroende på dess storlek, och att försumma den kan gefelaktiga resultat. De 3D effekterna av SSI orsakar inte höga vibrationer på grundav andra moder än den första böjmoden, och att anta en 2D bromodell är såledesgenerellt sett motiverat.Effekterna av SSI på jord–brosystemet i grunda jordar beror till stor del av kvotenmellan brons naturliga frekvens och jordens fundamentala frekvens. Beroende påvärdet på denna kvot kan effekten av att inkludera SSI i bromodeller bidra till attbron får en försumbar, konservativ, eller icke-konservativ respons, i jämförelse medbron med antagandet om fasta upplag.
QC 20200903
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Tell, Sarah. "Vibration mitigation of high-speed railway bridges : Application of fluid viscous dampers." Licentiate thesis, KTH, Bro- och stålbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205672.
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At the moment of writing, an expansion of the Swedish railway network has started, by constructions of new lines for high-speed trains. The aim is to create a high-speed connection between the most populous cities in Sweden - Stockholm, Göteborg and Malmö, and the rest of Europe. Thereby, the likelihood of faster, longer and heavier foreign trains crossing the Swedish lines is increased. However, this could be problematic since the dynamic response in railway bridges and, consequently, the risk of resonance increases with increasing train speeds. Bridges are usually designed based on contemporary conditions and future requirements are rarely considered, due to e.g. cost issues. Prospectively, the dynamic performance of existing bridges may become insufficient. Hence, the current expansion of the high-speed railway network results in an increased demand of innovative design solutions for new bridges and cost-efficient upgrading methods for existing lines. The aim of the present thesis is to propose a vibration mitigation strategy suitable for new and existing high-speed railway bridges. The main focus is a retrofit method with fluid viscous dampers installed between the bridge superstructure and the supports, which is intended to reduce the vertical bridge deck acceleration below the European design code limits. Furthermore, the intention is to investigate the efficiency of such a system, as well as to identify and analyse the parameters and uncertainties which could influence its functionality. In order to examine the applicability of the proposed retrofit, case studies, statistical screenings and sensitivity analyses are performed and analysed. Two different models, a single-degree-of-freedom system and a finite element model, are developed and compared. From the different models, it is possible to study the influence from the damper parameters, the variability of the material properties and different modelling aspects on the bridge response. After the installation of the fluid viscous dampers, it is found that the acceleration level of the bridge deck is significantly reduced, even below the design code requirements.I skrivande stund har en utbyggnad av det svenska järnvägsnätet initierats. Målet är att skapa en höghastighetsanslutning mellan de folkrikaste städerna i Sverige - Stockholm, Göteborg och Malmö, och vidare ut i Europa. Därmed ökar sannolikheten att snabbare, längre och tyngre utländska tåg korsar de svenska järnvägslinjerna. Dock kan detta bli problematiskt i och med att järnvägsbroars dynamiska respons och, följaktligen, risken för resonans ökar med ökad tåghastighet. Broar dimensioneras ofta utifrån nuvarande förutsättningar och hänsyn tas sällan till framtida hållbarhetskrav, exempelvis p.g.a. kostnadsbesparingar. Ur ett framtidsperspektiv kan därför det dynamiska beteendet hos befintliga broar komma att bli otillräckligt. Utbyggnaden av höghastighetsnätverket ökar därmed behovet av innovativa konstruktionslösningar för nya broar och kostnadseffektiva uppgraderingsmetoder för befintliga sträckor. Syftet med föreliggande avhandling är att föreslå en metod för att minska de vibrationsnivåer som kan uppstå i både nybyggda och befintliga järnvägsbroar för höghastighetståg. Huvudfokus är en eftermonteringsmetod med viskösa dämpare, som har installerats mellan brons överbyggnad och landfästen, för att minska brobanans vertikala acceleration under gällande europeiska dimensioneringskrav. Vidare avses att undersöka effektiveteten av ett sådant system, samt att identifiera och analysera de parametrar och osäkerheter som kan påverka dess funktionalitet. Fall- och parameterstudier, samt statistiska metoder används och utvärderas för att undersöka tillämpbarheten av den föreslagna vibrationsdämpningsmetoden. Två olika modeller, ett enfrihetsgradssystem och en finit elementmodell, har skapats och jämförts. Utifrån dessa modeller kan påverkan av dämparens parametrar, variabiliteten hos materialegenskaperna och behandlingen av olika modelleringsaspekter studeras. Från resultaten är det tydligt att brobanans accelerationsnivå avsevärt reduceras efter monteringen av viskösa dämpare, till och med under dimensioneringskraven.
QC 20170425
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Lestoille, Nicolas. "Stochastic model of high-speed train dynamics for the prediction of long-time evolution of the track irregularities." Thesis, Paris Est, 2015. http://www.theses.fr/2015PEST1094/document.
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Les voies ferrées sont de plus en plus sollicitées: le nombre de trains à grande vitesse, leur vitesse et leur charge ne cessent d'augmenter, ce qui contribue à la formation de défauts de géométrie sur la voie. En retour, ces défauts de géométrie influencent la réponse dynamique du train et dégradent les conditions de confort. Pour garantir de bonnes conditions de confort, les entreprises ferroviaires réalisent des opérations de maintenance de la voie, qui sont très coûteuses. Ces entreprises ont donc intérêt à prévoir l'évolution temporelle des défauts de géométrie de la voie pour anticiper les opérations de maintenance, et ainsi réduire les coûts de maintenance et améliorer les conditions de transport. Dans cette thèse, on analyse l'évolution temporelle d'une portion de voie par un indicateur vectoriel sur la dynamique du train. Pour la portion de voie choisie, on construit un modèle stochastique local des défauts de géométrie de la voie à partir d'un modèle global des défauts de géométrie et de big data de défauts mesurés par un train de mesure. Ce modèle stochastique local prend en compte la variabilité des défauts de géométrie de la voie et permet de générer des réalisations des défauts pour chaque temps de mesure. Après avoir validé le modèle numérique de la dynamique du train, les réponses dynamiques du train sur la portion de voie mesurée sont simulées numériquement en utilisant le modèle stochastique local des défauts de géométrie. Un indicateur dynamique, vectoriel et aléatoire, est introduit pour caractériser la réponse dynamique du train sur la portion de voie. Cet indicateur dynamique est construit de manière à prendre en compte les incertitudes de modèle dans le modèle numérique de la dynamique du train. Pour identifier le modèle stochastique des défauts de géométrie et pour caractériser les incertitudes de modèle, des méthodes stochastiques avancées, comme par exemple la décomposition en chaos polynomial ou le maximum de vraisemblance multidimensionnel, sont appliquées à des champs aléatoires non gaussiens et non stationnaires. Enfin, un modèle stochastique de prédiction est proposé pour prédire les quantités statistiques de l'indicateur dynamique, ce qui permet d'anticiper le besoin en maintenance. Ce modèle est construit en utilisant les résultats de la simulation de la dynamique du train et consiste à utiliser un modèle non stationnaire de type filtre de Kalman avec une condition initiale non gaussienneRailways tracks are subjected to more and more constraints, because the number of high-speed trains using the high-speed lines, the trains speed, and the trains load keep increasing. These solicitations contribute to produce track irregularities. In return, track irregularities influence the train dynamic responses, inducing degradation of the comfort. To guarantee good conditions of comfort in the train, railways companies perform maintenance operations of the track, which are very costly. Consequently, there is a great interest for the railways companies to predict the long-time evolution of the track irregularities for a given track portion, in order to be able to anticipate the start off of the maintenance operations, and therefore to reduce the maintenance costs and to improve the running conditions. In this thesis, the long-time evolution of a given track portion is analyzed through a vector-valued indicator on the train dynamics. For this given track portion, a local stochastic model of the track irregularities is constructed using a global stochastic model of the track irregularities and using big data made up of experimental measurements of the track irregularities performed by a measuring train. This local stochastic model takes into account the variability of the track irregularities and allows for generating realizations of the track irregularities at each long time. After validating the computational model of the train dynamics, the train dynamic responses on the measured track portion are numerically simulated using the local stochastic model of the track irregularities. A vector-valued random dynamic indicator is defined to characterize the train dynamic responses on the given track portion. This dynamic indicator is constructed such that it takes into account the model uncertainties in the train dynamics computational model. For the identification of the track irregularities stochastic model and the characterization of the model uncertainties, advanced stochastic methods such as the polynomial chaos expansion and the multivariate maximum likelihood are applied to non-Gaussian and non-stationary random fields. Finally, a stochastic predictive model is proposed for predicting the statistical quantities of the random dynamic indicator, which allows for anticipating the need for track maintenance. This modeling is constructed using the results of the train dynamics simulation and consists in using a non-stationary Kalman-filter type model with a non-Gaussian initial condition. The proposed model is validated using experimental data for the French railways network for the high-speed trains
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Rådeström, Sarah, and Viktor Tell. "Reduction of Vertical Acceleration in High-speed Railway Bridges Using Post-installed Viscous Dampers : A case study of the Bothnia Line." Thesis, KTH, Bro- och stålbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146086.
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Several of the bridges along the Bothnia railway line do not fulfill the requirements regarding vertical accelerations that are stated in current design codes. The acceleration of the bridges needs to be reduced, in order to make the Bothnia line suitable for high speed railway traffic. The aim with this thesis is to investigate if it is possible to reduce the vertical acceleration of insufficient bridges to an acceptable level by using post-installed dampers. The expectation was that this method could have major economic advantages compared to other rehabilitation methods. Five different bridges with post-installed dampers were simulated in verified MATLAB codes. The simulations were performed for two cases for each bridge: one where the eccentricities between the attachment of the damper and the centre of gravity of the bridge cross section was taken into consideration, and one where the influence from the eccentricities was excluded. The results showed that it is fully possible to reduce the acceleration to an acceptable level with the use of external damper configurations. It was also shown that the eccentricities of the bridges had a high impact in this kind of simulations. Furthermore, some supplementary investigations regarding the location and position of the damper, were done as well. Finally, a brief analysis and discussion regarding the practical implementation of the post-installed was performed. One challenge is to anchor the damper and take care of the resulting forces in a favourable and safe way.Flertalet broar längs med Botniabanan uppfyller inte de krav som ställs på de vertikala accelerationsnivåerna i gällande dimensioneringsnormer. Dessa accelerationer måste reduceras för att göra Botniabanan tillgänglig för trafik med höghastighetståg. I denna uppsats undersöks det huruvida det är möjligt att sänka accelerationen i bristfälliga broar med hjälp av eftermonterade externa dämpare. Förväntningen var att denna metod skulle ha stora ekonomiska fördelar gentemot andra upprustningsmetoder. Fem broar med eftermonterade dämpare har simulerats i verifierade MATLAB-koder. Simuleringarna utfördes på två olika sätt för varje bro: i en kod togs eccentriciteten mellan dämparinfästningen och tyngdpunktslinjen för bron i beaktande, och i den andra koden försummades all inverkan av eccentriciteten. Resultatet från simuleringarna visade att det är fullt möjligt att reducera accelerationerna till en acceptabel nivå med hjälp av externa dämpningskonfigurationer. Eccentriciteten visade sig även ha stor inverkan på resultatet i denna typ av simulering. Dessutom utfördes några kompletterande undersökningar gällande längd, position och vinkel på dämparen. Slutligen analyserades och diskuterades den praktiska implementeringen av de eftermonterade dämparna. En utmaning är att förankra dämparna och föra ner de resulterande krafterna på ett fördelaktigt och säkert sätt.
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Amaral, Pollyana Gil Cunha. "Análise dinâmica de pontes para trens de alta velocidade." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-13042017-113433/.
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Este trabalho utiliza uma metodologia simplificada de análise dinâmica para o estudo das vibrações em pontes ferroviárias, produzidas pela passagem de um trem de alta velocidade, associadas à presença de irregularidades nos trilhos. Iniciou-se o estudo a partir de um modelo do veículo composto por quinze graus de liberdade, referentes aos deslocamentos verticais e horizontais transversais, e rotações em torno dos eixos longitudinal, transversal e vertical. Os modelos dinâmicos do trem e da ponte foram tratados de forma desacoplada, sendo conectados pelas forças de interação trem-ponte. Desta forma, foram calculados os carregamentos provenientes da modelação dinâmica do trem, adotando-se inicialmente a hipótese de tabuleiro rígido e indeslocável e, ainda, considerando-se a presença de irregularidades geométricas nos trilhos no plano vertical. Neste trabalho, foi considerado um estudo de caso utilizando-se o modelo veicular Alfa Pendular, avaliando-se a resposta dinâmica do trem e da estrutura, considerando o efeito das irregularidades geométricas nos trilhos, bem como a presença do lastro. As forças de interação obtidas da modelagem do veículo foram aplicadas em um modelo estrutural de alta hierarquia da ponte, dividido em elementos finitos de casca, sendo que em cada nó do modelo da ponte foram especificados os esforços obtidos da análise dinâmica do veículo. Para representar a passagem do comboio sobre a ponte, foram utilizadas funções que descrevem as forças de interação trem-ponte em cada nó do modelo da ponte, em cada intervalo de tempo, até que todo o trem tenha percorrido o comprimento da ponte. A consideração de tabuleiro rígido indeslocável foi corrigida por meio de um processo iterativo, de forma que os deslocamentos do tabuleiro obtidos para a primeira determinação dos esforços de interação foram somados às irregularidades do trilho (excitação de suporte aplicada nas rodas do trem). Com isso, foi possível identificar a resposta dinâmica proveniente da carga em movimento e das irregularidades geométricas nos trilhos, avaliando o conforto dos passageiros no interior do vagão. Por fim, realizou-se uma análise de distribuição estatística para avaliar a probabilidade de se ultrapassar os limites estabelecidos pelo Eurocode.This thesis resorts to a simplified methodology of dynamic analysis for the study of vibrations in railway bridges, produced by the passage of a high speed train, associated to the presence of irregularities in the rails. The study started from a vehicle model composed of fifteen degrees of freedom, namely, vertical and lateral displacements, and rotations about the longitudinal, lateral and vertical axes. The dynamic models of the train and the bridge were treated as uncoupled, yet being bound by the interaction train-bridge forces. Thus, the loads from the dynamic model of the train were calculated, adopting initially the hypothesis of rigid and fixed deck and also, considering the presence of geometric irregularities in the vertical track plane. In this work, we considered a case study using the Alfa Pendular vehicle model, evaluating the dynamic response of the train and the structure, considering the effect of the geometric irregularities at the tracks, as well as the presence of the ballast. The interaction forces obtained from the model of the vehicle were applied in a high hierarchy structural model of the bridge, divided into shell finite elements, specifying the forces obtained from the dynamic analysis of the vehicle at each node of the bridge model. To represent the train passage on the bridge, functions were used to describe the bridge-train interaction forces at each node of the bridge model at each time interval, until the entire train had travelled the bridge length. The consideration of rigid and fixed deck was corrected by means of an iterative process, so that the deck displacements obtained for a first determination of the interaction forces were added to the rail irregularities (excitation applied to the train wheels). Thus, it was possible to identify the dynamic response caused both by the moving loading and the geometrical irregularities of the tracks, evaluating the comfort of the passengers inside the wagon. Finally, a reliability study was carried out to evaluate the probability of exceeding the limits established by Eurocode.
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Mellat, Peyman. "Dynamic analysis of soil-steel composite bridges for high speed railway traffic : Case study of a bridge in Märsta, using field measurements and FE-analysis." Thesis, KTH, Bro- och stålbyggnad, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-125342.
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Soil-steel composite bridge refers to structures where a buried flexible corrugated steel pipe works in composite action with the surrounding soil. These structures are being increasingly used in road and railway projects as an alternative to standard type bridges, e.g. short- and medium span concrete beam- and portal frame bridges. On account of their economic advantage and short and easy construction operation, soil-steel composite bridges are getting more popular as railway crossings located far from the cities at the heart of the nature. In this research, the dynamic behaviour of soil-steel composite bridges under high-speed train passages is studied. The studied case is a short span soil-steel composite railway bridge located in Märsta close to Stockholm. The behaviour of the bridge is first observed through field measurements in terms of deflections, stresses, and accelerations at several locations on the bridge. The measured responses are then analysed in order to predict the properties of the soil and steel material working in composite action. Subsequently, 2D and 3D finite element models are developed in order to simulate the behaviour of the bridge. The models are calibrated using the field measurements through several parametric studies. The 3D-model also enables estimation of the load distribution, which is found to increase at higher train speeds. An effective width to be used in 2D analyses is proposed. Finally, the response of the bridge is studied under high-speed train models according to Eurocode.
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Perrin, Guillaume. "Random fields and associated statistical inverse problems for uncertainty quantification : application to railway track geometries for high-speed trains dynamical responses and risk assessment." Phd thesis, Université Paris-Est, 2013. http://pastel.archives-ouvertes.fr/pastel-01001045.
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Les nouvelles attentes vis-à-vis des nouveaux trains à grande vitesse sont nombreuses: on les voudrait plus rapides, plus confortables, plus stables, tout en étant moins consommateur d'énergie, moins agressif vis-à-vis des voies, moins bruyants... Afin d'optimiser la conception de ces trains du futur, il est alors nécessaire de pouvoir se baser sur une connaissance précise de l'ensemble des conditions de circulations qu'ils sont susceptibles de rencontrer au cours de leur cycle de vie. Afin de relever ces défis, la simulation a un très grand rôle à jouer. Pour que la simulation puisse être utilisée dans des perspectives de conception, de certification et d'optimisation de la maintenance, elle doit alors être tout à fait représentative de l'ensemble des comportements physiques mis en jeu. Le modèle du train, du contact entre les roues et le rail, doivent ainsi être validés avec attention, et les simulations doivent être lancées sur des ensembles d'excitations qui sont réalistes et représentatifs de ces défauts de géométrie. En ce qui concerne la dynamique, la géométrie de la voie, et plus particulièrement les défauts de géométrie, représentent une des principales sources d'excitation du train, qui est un système mécanique fortement non linéaire. A partir de mesures de la géométrie d'un réseau ferroviaire, un paramétrage complet de la géométrie de la voie et de sa variabilité semblent alors nécessaires, afin d'analyser au mieux le lien entre la réponse dynamique du train et les propriétés physiques et statistiques de la géométrie de la voie. Dans ce contexte, une approche pertinente pour modéliser cette géométrie de la voie, est de la considérer comme un champ aléatoire multivarié, dont les propriétés sont a priori inconnues. En raison des interactions spécifiques entre le train et la voie, il s'avère que ce champ aléatoire n'est ni Gaussien ni stationnaire. Ce travail de thèse s'est alors particulièrement concentré sur le développement de méthodes numériques permettant l'identification en inverse, à partir de mesures expérimentales, de champs aléatoires non Gaussiens et non stationnaires. Le comportement du train étant très non linéaire, ainsi que très sensible vis-à-vis de la géométrie de la voie, la caractérisation du champ aléatoire correspondant aux défauts de géométrie doit être extrêmement fine, tant du point de vue fréquentiel que statistique. La dimension des espaces statistiques considérés est alors très importante. De ce fait, une attention toute particulière a été portée dans ces travaux aux méthodes de réduction statistique, ainsi qu'aux méthodes pouvant être généralisées à la très grande dimension. Une fois la variabilité de la géométrie de la voie caractérisée à partir de données expérimentales, elle doit ensuite être propagée au sein du modèle numérique ferroviaire. A cette fin, les propriétés mécaniques d'un modèle numérique de train à grande vitesse ont été identifiées à partir de mesures expérimentales. La réponse dynamique stochastique de ce train, soumis à un très grand nombre de conditions de circulation réalistes et représentatives générées à partir du modèle stochastique de la voie ferrée, a été ainsi évaluée. Enfin, afin d'illustrer les possibilités apportées par un tel couplage entre la variabilité de la géométrie de la voie et la réponse dynamique du train, ce travail de thèse aborde trois applications
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Shu, Jiangpeng, and Ziye Zhang. "Damage detection on railway bridges using Artificial Neural Network and train induced vibrations." Thesis, KTH, Bro- och stålbyggnad, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-99387.
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A damage detection approach based on Artificial Neural Network (ANN), using the statistics of structural dynamic responses as the damage index, is proposed in this study for Structural Health Monitoring (SHM). Based on the sensitivity analysis, the feasibility of using the changes of variances and covariance of dynamic responses of railway bridges under moving trains as the indices for damage detection is evaluated. A FE Model of a one-span simply supported beam bridge is built, considering both single damage case and multi-damage case. A Back-Propagation Neural Network (BPNN) is designed and trained to simulate the detection process. A series of numerical tests on the FE model with different train properties prove the validity and efficiency of the proposed approach. The results show not only that the trained ANN together with the statistics can correctly estimate the location and severity of damage in the structure, but also that the identification of the damage location is more difficult than that of the damage severity. In summary, it is concluded that the use of statistical property of structural dynamic response as damage index with the Artificial Neural Network as detection tool for damage detection is reliable and effective.
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Llorens, García Andrea. "Traffic induced vibrations on a portal frame railway bridge : Comparison of theory and measurements." Thesis, KTH, Bro- och stålbyggnad, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-36351.
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The effect of different vertical support stiffness of a frame railway bridge is investigated in this study. Due to the dynamic loads of the high speed trains that run over the railway bridges, the response of these structures is far from the static effects. The frame bridge chosen for this study is the Rössjö bridge, located on the Bothnia Line, the first high speed railway built in Sweden. Using a theoretical model of this bridge, the eigenfrequencies of the structure and the vertical accelerations of the deck are evaluated. Not only different vertical support stiffness, but also different trains and train speeds are studied. Finally, some real in-situ measurements are compared with the results from the theoretical model.
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Gry, Laurent. "Modélisation du comportement dynamique d'une voie TGV pour la réduction du bruit de roulement." Châtenay-Malabry, Ecole centrale de Paris, 1995. http://www.theses.fr/1995ECAP0419.
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Un modèle de voie périodique a été développé afin de réduire le bruit émis dans l'environnement durant le passage d'un train. Ce modèle, prenant en compte les déformations de la section du rail, couvre une large gamme de fréquences, 0 - 5000 Hz. La considération d'un appui discret le rend cependant moins performant dans les hautes fréquences, pour lesquelles les ondes propagatives émises sur une travée ont une longueur d'onde proche de la longueur d'appui. Une méthode générale d'analyse des milieux périodiques unidimensionnels est alors proposée afin de prendre en compte l'effet de la longueur d'appui
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Connolly, David. "Ground borne vibrations from high speed trains." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8302.
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A consequence of high speed rail transportation is the generation of elevated ground borne vibrations. This thesis presents several original contributions towards the prediction of these vibrations. Firstly, a new three dimensional finite element model capable of vibration prediction was developed. Its main feature was its ability to model complex track geometries while doing so through a fully coupled vehicle-tracksoil system. Model output was compared to experimental results obtained during this thesis and also to independent data sets. It was shown to predict velocity time histories, vibration frequency spectrums and international vibration descriptors with high accuracy. An appraisal of the suitability of a finite difference time domain modelling approach for railway vibration prediction was also undertaken. This resulted in the development of a new ‘higher order’ perfectly matched layers absorbing boundary condition. This condition was found to offer higher performance in comparison to current alternative absorbing boundary conditions. Field work was then undertaken on high speed lines with varying embankment conditions in Belgium and England. Vibration data was recorded up to 100m from each track and geophysical investigations were performed to determine the underlying soil properties. The results were used for numerical model validation and also to provide new insights into the effect of various embankment conditions on vibration propagation. It was found that embankments generate higher frequency excitation in comparison to nonembankment cases and that cuttings generate higher vibration levels than noncuttings. Once validated the finite element model was used to provide new insights into the effect of train speed, embankment constituent materials and railway track type on vibration levels. It was found that the shape and magnitude of ground vibration increased rapidly as the train’s speed approached the Rayleigh wave speed of the underlying soil. It was also found that ballast, slab and metal tracks produced similar levels of vibration and that stiffer embankments reduced vibration levels at distances near and far from the track. Two vibration mitigation techniques were also explored through numerical simulation. Firstly, an analysis was undertaken to determine the ability of a new modified ballast material to actively isolate vibration within the track structure. Secondly, wave barrier geometries were investigated to optimise their performance whilst minimising cost. It was found that barrier depth was the most influential parameter, whereas width had little effect. Additionally, geometry optimisation was found to result in a 95% cost saving in comparison to a base case. Using a vast array of results generated using the previously developed finite element model, a new empirical prediction model was also developed, capable of quickly assessing vibration levels across large sections of track. Unlike currently available empirical models, it was able to account for soil properties in its calculation and could predict a variety of international vibration metrics. It was shown to offer increased prediction performance in comparison to an alternative empirical model.
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Brockie, N. J. W. "The aerodynamic drag of high speed trains." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234147.
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Wong, Wing-sum Angela. "Possibility of the development of high speed train between Hong Kong and Mainland China." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31627699.
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Wiberg, Niklas, and Jasmin Halilovic. "Train Induced Vibration Analysis of an End-frame Bridge : Numerical Analysis on Sidensjövägen." Thesis, KTH, Bro- och stålbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231911.
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Higher speeds and higher capacity will cause the Swedish rail network to be exposed to disturbing dynamic effects. Higher speeds cause higher vertical acceleration levels of the bridge deck. In this thesis, a numerical analysis of a three span end-frame bridge subjected to train induced vibrations is performed. The aim is to identify which structural components and boundary conditions that affect the dynamic behavior of the bridge. Furthermore, the influence of soil structure interaction (SSI) will be investigated as it may have contribution to the stiffness and damping of the structural system. In order to capture the dynamic response of the bridge, an analysis in the frequency domain was preformed where frequency response functions (FRF) and acceleration envelopes were obtained. For this purpose, a detailed FE-model in 3D was created. Three different cases were studied, model subjected to ballast, model subjected to soil and model subjected to both ballast and soil in coherence. A high speed load model (HSLM) was used to create simulation of train passages at different speeds and applied to all cases so that the bridge deck accelerations could be studied. A simplified 2D-model with impedance functions representing the soil-structure interaction was created to validate the results from the detailed 3D-model and for practical design purposes. The result of this numerical analysis showed that the vertical accelerations were within acceptable levels of the maximum allowed limits given in governing publications. Considering the surrounding soil, the results revealed an increase of the dynamic response in the midspan at resonant frequency. However, it was identified that this behavior is not explained by the influence of soil structure interaction but rather the change in boundary conditions of the end-shields. The same dynamic behavior was identified for the simplified 2D-model, with a slight underestimation of the vertical accelerations at resonance.
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Thomas, Dirk. "Lateral Stability of High-Speed Trains at Unsteady Crosswind." Licentiate thesis, KTH, Aeronautical and Vehicle Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11377.
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Crosswind stability of rail vehicles has been a research area for several decades,mainly motivated by vehicle overturning accidents and higher speeds, but in recenttimes also by issues of lower energy consumption and track maintenance costsdemanding lower vehicle weights. During everyday operation, rail vehicles are subjectedto large lateral influences from track irregularities, track curves and crosswind,leading to large suspension deflections and increased crosswind sensitivity.Also unsteady crosswind like gusts calls for attention. Simulations of possible vehicleoverturning are necessary, but need to take large deflections and high shear inthe suspension into account. If delivering reasonable results, simulations representan important tool for overturning prediction of the vehicle.
In the present work, multibody simulations of a high-speed vehicle at large lateralinfluences from track curves and track irregularities have been carried out, using ahalf-vehicle model in 2D and a model of a whole vehicle in 3D. The vehicle modelsalso include different suspension models. Corresponding field measurements ofthe relative lateral and vertical deflections in the secondary suspension have beenperformed on a fast train and used for validation of the multibody simulations,resulting in good agreement between measurements and simulations.
The 3D vehicle model was further used to study the vehicle response to unsteadycrosswind during curve negotiation where aerodynamic loads obtained by unsteadyComputational Fluid Dynamics, namely Detached Eddy Simulations, representingthree types of gusts were used. In addition, the method of Quasi Transient GustModelling was evaluated in terms of overturning risk. Strong lateral and roll responsesof the vehicle and influences of the gust duration and the relative differencebetween mean and maximum wind speed were observed. Further, variations of suspensionand mass properties of the vehicle were performed to study the influenceon crosswind sensitivity. The position of the centre of mass of the carbody and thelateral bumpstop clearance showed significant influence on the crosswind stability.
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Gilbert, Timothy. "Aerodynamic effects of high speed trains in confined spaces." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/4748/.
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This research aims to describe the effect which changing the geometry of confining structures has on transient aerodynamic effects induced by passing high-speed trains. A moving-model high-speed train was fired past walls, partially-enclosed tunnels, and single-track tunnels. A control experiment was carried out in the open air. 3D air velocity components and static pressure were measured inside the structures. The main findings are as follows. The durations and magnitudes of the pressure loads and maximum air velocities were found to be dependent on: the lateral separation of the walls; whether walls on both sides of the tracks are placed symmetrically or asymmetrically; the longitudinal positioning of the sensor in relation to the length of the tunnel; the cross-sectional area of the tunnel; the tunnel’s length in relation to the train’s length; and, finally, the size of an opening in the cross-section of a tunnel in relation to the tunnel’s internal perimeter. Maximum velocities were affected by confinement as a result of changes to: helical vortices in the wake; durations and magnitudes of the pressure fluctuation around the tail; the piston effect in tunnels; the boundary layer shape; and secondary flows induced by pressure gradients in the tunnel cross-section caused by vents.
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O'Neill, Rebecca Marie. "Claims, trains and frames : the case of High Speed Two." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7169/.
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Although evidence is utilised by claims-makers to strengthen their arguments, quality evidence is not necessarily the precursor to driving or explaining policy decisions. Actors who share a common frame are more likely to perceive a policy problem and solution in the same way. Therefore, decision-making processes are not about finding the highest quality evidence to support decisions; they becomes about which actor is better at presenting a believable argument that will persuade others their claims are more agreeable. Using a single case study design, qualitative methods are used to examine the role of evidence in the context of the construction of a new high speed rail network in the UK, High Speed Two (HS2). It examines how these actors frame the debate and how they negotiate evidence with one another in different policy environments, through a process of claims-making. The study provides a new perspective to the High Speed Two debate, one which has received little attention in academic circles. A claims-making framework is utilised to provide a rich description of the naturalistic processes occurring in the decision-making processes of High Speed Two and it offers a sophisticated understanding of how evidence interpreted and negotiated by policy actors. In addition, it unpacks and refines notions of argumentation which acknowledges the subjective nature of evidence.
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王穎琛 and Wing-sum Angela Wong. "Possibility of the development of high speed train between Hong Kong and Mainland China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31627699.
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Einhorn, Jacob. "Preview information in locomotive in-cab displays for high-speed trains." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/45483.
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Latorre, Iglesias Eduardo. "Component-based model to predict aerodynamic noise from high-speed trains." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/384285/.
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The aerodynamic noise produced by train pantographs and bogies is significant for typical speeds of modern high-speed trains. In order to reduce the negative environmental impact of high-speed train noise, the aerodynamic noise should be tackled in an early stage of the train design. In recent years, Computational Fluid Dynamics (CFD) and Computational AeroAcoustics (CAA) models have been developed in order to predict aerodynamic noise but they are very computationally-intensive. In this thesis, a semi-empirical component-based model is developed for quick prediction of the aerodynamic noise radiated by a high-speed train pantograph and bogie. The overall noise from the pantograph and bogie is obtained as the incoherent sum of the contributions predicted from the individual components. The model empirical constants are obtained using an experimental database built from data found in the literature and noise tests carried out during this work to evaluate the effect of different geometries and inflow conditions. For the pantograph, the struts are approximated as cylinders with a particular cross-section. To extend the available database, anechoic wind tunnel noise tests were carried out using cylinders with different cross-sections for different configurations. The predictions are compared with available noise measurements using a full-size pantograph showing good agreement. For the bogie case, the prediction model is developed by identifying each of the bogie components with simple shapes. Anechoic wind tunnel noise measurements were carried out using simple shapes to determine the empirical constants of the model. Additionally, scale train car body and bogie mock-ups were used, allowing for model validation and also providing useful information on the dependence on different factors of the aerodynamic noise generation in the bogie region. The results show the potential of the model to be used as an engineering tool to predict aerodynamic noise from train pantographs and bogies, allowing the effect of design modifications of components to be assessed and low-noise technology to be developed.
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Guillou, Florian. "CFD Study of the Flow around a High-Speed Train." Thesis, KTH, Aerodynamik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-102033.
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This document is a report summering the master thesis work dealing with the Computational Fluid Dynamic (CFD) study of the flow around a high-speed train. The model is a scaled 1:50 generic train with two cars, one inter-car gap and simplified bogies. A platform is set on the side of the train since one of the aim of the study is to look at the consequences of the phenomena in the wake on people or objects standing on the platform. The slipstream is one of this phenomena, it is due to the fact that the viscous air is dragged when the train is passing. If too strong, it can move or destabilize people or objects on the platform. In addition of the slipstream study, a velocity profile study, a drag and lift coefficients analyze as well as a Q-factor study and a frequency study have been realized. Some results of these different studies are compared with the ones obtained on the same model with a Delayed Detached Eddy Simulation (DDES). Since the flow is turbulent, for those different studies, the flow has been simulated with a Reynolds Averaged Navier-Stokes equation model (RANS) which is the k-ω SST model for the turbulence. The study of the slipstream allowed to calculate the Technical Specification for Interoperability (TSI) which must not be higher that the European Union requirement set at 15.5 m/s, the result obtained is 8.1 m/s which is then lower than the limit. The velocity profile shows similarities with the DDES results even though it is less detailed. The same conclusion is done for the Q-plot where is clearly visible the two counter-rotating vortices in the wake. Finally, a Fast Fourier Transform algorithm has been applied to instantaneous velocity results in the wake of the train in order to get the frequency of the aerodynamic phenomena in that wake. The main frequency is 25 Hz and corresponds to a Strouhal number of 0.1, quite closed to the results obtained with DDES which is 0.085. The results of the RANS and DDES are reasonably similar and by regarding at the large difference between the cell numbers (respectively 8 500 000 and 20 000 000) it can be conclude that in some ways the RANS model can be preferred at the DDES to save time for the computation but it does not contain the small scales resolved by the DDES.
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Haag, Maria. "Problems concerning pantograph collection of current during winter for high speed trains." Thesis, KTH, Maskinkonstruktion (Inst.), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-99339.
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The idea of making this report was to try and shed light on the many problems of pantograph collection of current during winter time for high speed trains. The greatest difference between Sweden and other countries who already have built high speed rails is our yearly severe winter conditions. The problem about pantograph collection during winter is that the contact between the pantograph and the contact wire gets worse if ice isolates in between those two. That creates electric arcs that can harm both the pantograph and the overhead contact wire. For a high speed track the problems are expected to be even greater. It’s important that the Swedish Transport Administration, at an early stage, learns what causes the delays and the unwanted stops. My work started by doing a thorough literature study, where I tried to summon the overhead contact line theory from a winter perspective. After this a number of attempts have been made to illustrate different solutions on how to avoid that ice stays on the overhead contact line or the pantograph. In the first attempt I examined the thickness the ice would get on the contact wire if the air temperature suddenly fell from 0 C till 5 C and super cooled rain would fall for an entire 24-hour period. In my second attempt I tried the possibility to use a heated pantograph combined with an ice scraper. I used an American ice scraper as basic idea, but modified the contact strip part and made its shape cylindrical and hollow. The idea was that the scraper would reduce the ice on the wire and that the heated brass contact strip would melt the rest. In attempt three I looked into other materials that would be more suited for winter climate. As suspected the already existing materials, are not good enough and the futuristic ones are too expensive at the present time. Attempt number four was all about heating the contact wire with a magnetron that was going to be assembled on the pantograph. Unfortunately this result was not a success as it turned out that ice does not heat very well from microwaves. In the fifth attempt I focused on ice scrapers by studying tribology. Using an ice scraper may work, but probably best in combination with some of the other methods. Testing how this would be done in the best way will take some time. In the sixth attempt I looked into the possibility of heating the contact wire by adding extra current to the system. This is the way of handling the problem that I believe to be the most promising. In addition to these approaches, a simulation was made to show a phase change in the computer program Comsol.Syftet med examensarbetet är att belysa problematiken kring strömavtagning vintertid för hög-hastighetståg. De största skillnaderna mellan Sverige och många andra länder som redan byggt höghastighetsbanor är, att vi årligen drabbas av kraftig vinter och de länder som har vinter oftast har annan kraftförsörjning. Problemet med strömavtagning vintertid är att kontakten mellan strömavtagare och kontaktledning försämras om det ligger is emellan. Då skapas överslag i form av ljusbågar som då sliter hårt på både strömavtagare och kontaktledning. För en höghastig-hetsbana förväntas problemen öka ytterligare. En stor del av poängen med att bygga en sådan är att vinna tid, så om banan drabbas av frekventa störningar under vinterhalvåret är vitsen borta. Det är viktigt att Trafikverket redan i ett tidigt skede får klart för sig orsaken. Arbetet började med en grundlig litteraturstudie där jag försökte sammanställa kontaktlednings-teorin med utgångspunkten vinter med fokus på åtgärder. Jag använde därefter sex olika ansatser, på olika sätt att förhindra isbildning på kontakttråd och slitskena. I den första undersökningen tog jag reda på vilken istjocklek det skulle bli på kontaktledningen om lufttemperaturen sjönk momentant från till och det kontinuerligt skulle regna underkylt under 1 dygn. C 0 C 5 I den andra undersökningen utredde jag möjligheten att använda en varm strömavtagare kombin-erad med isskrapa. Jag använde en amerikansk grundidé men modifierade mässingslitdelen samt gjorde den cylindrisk och ihålig. Tanken var sedan att skrapan skulle reducera isen till max 3 mm på tråden och att det uppvärmda mässingsröret skulle klara att smälta resten. I undersökning tre tittade jag på möjligheten att välja bättre material ur vintersynpunkt. Som jag misstänkte har de alternativa, redan befintliga materialen idag stora nackdelar och de framtida en tid kvar innan de blir prisvärda. Fjärde undersökningen gick ut på att värma kontakttråden med en magnetron monterad på slitskenan. Detta försök var inte helt lyckat, eftersom is inte värms speciellt bra av mikrovågor. I undersökning fem fokuserade jag på isskrapor och för detta krävdes en fördjupning inom ämnet tribologi. En isskrapa skulle kunna användas, men då troligen i kombination till någon av de övriga metoderna. Att testa ut hur detta skulle göras på bästa sätt kommer att ta lång tid. Den sjätte ansatsen behandlade uppvärmning av kontaktledningen med hjälp av krypström. Denna lösning är nog den jag personligen tror mest på. Dessutom modellerade jag en fasomvandling och förutspådde dess påverkan på värmeöver-föringsförmågan genom att göra en simulering i dataprogrammet Comsol.
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Muld, Tomas W. "Slipstream and Flow Structures in the Near Wake of High-Speed Trains." Doctoral thesis, KTH, Farkost och flyg, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-94182.
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Train transportation is a vital part of the transportation system of today. Asthe speed of the trains increase, the aerodynamic effects become more impor-tant. One aerodynamic effect that is of vital importance for passengers’ andtrack workers’ safety is slipstream, i.e. the induced velocities by the train.Safety requirements for slipstream are regulated in the Technical Specificationsfor Interoperability (TSI). Earlier experimental studies have found that forhigh-speed passenger trains the largest slipstream velocities occur in the wake.Therefore, in order to study slipstream of high-speed trains, the work in thisthesis is devoted to wake flows. First a test case, a surface-mounted cube, issimulated to test the analysis methodology that is later applied to two differ-ent train geometries, the Aerodynamic Train Model (ATM) and the CRH1.The flow is simulated with Delayed-Detached Eddy Simulation (DDES) andthe computed flow field is decomposed into modes with Proper Orthogonal De-composition (POD) and Dynamic Mode Decomposition (DMD). The computedmodes on the surface-mounted cube compare well with prior studies, whichvalidates the use of DDES together with POD/DMD. To ensure that enoughsnapshots are used to compute the POD and DMD modes, a method to inves-tigate the convergence is proposed for each decomposition method. It is foundthat there is a separation bubble behind the CRH1 and two counter-rotatingvortices behind the ATM. Even though the two geometries have different flowtopologies, the dominant flow structure in the wake in terms of energy is thesame, namely vortex shedding. Vortex shedding is also found to be the mostimportant flow structure for slipstream, at the TSI position. In addition, threeconfigurations of the ATM with different number of cars are simulated, in orderto investigate the effect of the size of the boundary layer on the flow structures.The most dominant structure is the same for all configurations, however, theStrouhal number decreases as the momentum thickness increases. The velocityin ground fixed probes are extracted from the flow, in order to investigate theslipstream velocity defined by the TSI. A large scatter in peak position andvalue for the different probes are found. Investigating the mean velocity atdifferent distances from the train side wall, indicates that wider versions of thesame train will create larger slipstream velocities.QC 20120530
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Wu, Kwun Hing. "Aerodynamic aspects of high-speed railway underground station with adjoining tunels /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?MECH%202008%20WU.
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Lee, Sun Ung. "Dynamics of high-speed rotating machines." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326078.
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Chung, Man Kit. "Two essays on the economic impacts of high-speed railway in China." HKBU Institutional Repository, 2014. https://repository.hkbu.edu.hk/etd_oa/92.
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The thesis contains two essays on the economic impacts of high-speed railway (HSR) in China. Utilizing a unique data set of towns in Dongguan, a city in South China, it provides empirical evidence on whether HSR affects economic growth and efficiency or not. The first essay uses the generalized method of moments (GMM) to estimate a dynamic panel data model of the town economies. The empirical results suggest that both HSR and expressway have a positive impact on the general economic development of the towns. However, HSR does not have a significant effect on the development of the manufacturing sector, while expressway does in this regard. These findings lend indirect support to the common argument that HSR can benefit the tertiary sector, but not necessarily other sectors. The second essay investigates the relationship between the advent of HSR and productive efficiency of the manufacturing sector. Using a stochastic frontier approach, it provides empirical evidence that proximity to expressway, rather than to HSR, enhances the efficiency of industrial enterprises.
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Mellier, Carine. "Optimal Design of Bridges for High-Speed Trains : Single and double-span bridges." Thesis, KTH, Bro- och stålbyggnad, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-36354.
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To deal with an increasing demand in transportation, trains are made longer and faster. Higher speeds imply higher impacts on bridges. Therefore, structures have to be designed to resist these new constraints. The Eurocode (2002) introduced additional checks for the design of high-speed railway bridges. Among them, the maximum vertical deck acceleration criterion often determines alone the design of the structure. Tests on shake table brought to the conclusion that vertical bridge deck acceleration should never exceed 3.5 m/s2 for ballasted tracks. This master thesis investigates the optimization of cross section parameters of single-track simply supported and double-span bridges based on the limit of the maximum vertical deck acceleration criterion. The first natural frequency is considered as a proof of the feasibility of the structure. The optimization is carried out through MATLAB for both types of bridges. The deck acceleration of simply supported bridges is analytically calculated using the Train Signature (ERRI D214 1999) in MATLAB. The dynamic calculations of double-span bridges are implemented through the finite element software ABAQUS. The implemented programs have been verified by comparison to values of simple cases found in the literature. Structures are tested under the influence of the ten HSLM-A trains of the Eurocode running at speeds between 150 km/h and 350 km/h. Optimization algorithms are presented and compared in this study but their applicability in such context is questioned. Indeed, as the problem contains several suitable minima, the algorithms, which end in one solution, are not adapted. To overtake this difficulty, a scanning of the interesting zone is advised. However, the latter is very time consuming, even more if the finite element analysis is used. Suggestions to decrease analysis time are presented in this report. Single span composite bridges with a span longer than 20 m appeared to be impossible to optimize within the objectives defined in this work (i.e. considering limits of deck acceleration and first natural frequency), which draws doubts about their suitability for high-speed railways. Nevertheless, simply supported bridges made of concrete seem more adapted for high-speed railways and their optimized parameters are presented in this work. Optimized parameters for double-span concrete bridges are also presented.
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Karis, Tomas. "Track Irregularities for High-Speed Trains : Evaluation of their correlation with vehicle response." Thesis, KTH, Järnvägsteknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156640.
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Wong, Chor-fung, and 黃楚峰. "An analysis of the agenda-setting process: a study of the Guangzhou-Shenzhen-Hong Kong express rail link." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B46778160.
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Tola, Akale Merid. "Predicting high-speed milling dynamics using stereolithography." Diss., Wichita State University, 2010. http://hdl.handle.net/10057/3659.
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Stereolithographic (SL) models have been successfully utilized during product development and the early stages of process design. In this research, SL models were utilized to predict the natural frequencies of high-speed cutting tools. Most common practices utilize theoretical or numerical methods to evaluate tool designs by using simplifying assumptions. However, these results may fail to accurately predict stability limits of the machining system.
This research developed a proactive approach for evaluating tool design, which minimizes the risk of ordering the wrong tool and sacrificing the most economic machining condition. Experiments have indicated that SL models correlate well with test results performed on actual machining systems. Consequently, SL models of selected tool designs were constructed and utilized to predict the dynamic characteristics and the stability limits of the machining system.
Using stereolithographic models, practitioners can generate stability lobe diagrams and study tool design alternatives before producing or ordering a required tool.Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering
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Rashid, Shahbaz. "Parametric study of bridge response to high speed trains, ballasted track on concrete bridges." Thesis, KTH, Bro- och stålbyggnad, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-99385.
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When a train enters a bridge, passenger sitting inside will feel a sudden bump in the track, which not only affect the riding comfort of the passengers but also put a dynamic impact on the bridge structure. Due to this impact force, we have very serious maintenance problems in the track close to the bridge structure. This sudden bump is produced when train travelling on the track suddenly hit by a very stiff medium like bridge structure. In order to reduce this effect, transition zones are introduced before the bridge so that the change in stiffness will occur gradually without producing any bump. This master thesis examine the effect of track stiffness on the bridge dynamic response under different train speeds from 150 to 350 km/h with interval 5 km/h and also estimate the minimum length of transition zones require to reduce the effect of change in stiffness on the bridge. Study also gives us some guidelines about the choice of loading model of the train, location of maximum vertical acceleration, effect of ballast model on the results and minimum length of transition zone needs to include in the bridge-track FE-model, for dynamic analysis of the concrete bridges. To carry out this research MATLAB is used to produce an input file for the ABAQUS FEM program. ABAQUS will first read this file, model the bridge and then analysis the bridge. MATLAB will again read the result file, process the result data and plot the necessary graphs. The Swedish X2000 train is used for this study, which has been modeled with two different methods: moving load model and sprung mass model, in order to see the difference in results. For verification of the MATLAB-ABAQUS model, a 42m long bridge is analysed and results are compared with known results. In this study, concrete simply supported bridges with spans of 5, 10, 15, 20, 25 m have been analysed.
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Marinakos, Helias John. "Effects of control automation on operator attention and risk probability in high speed trains." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42675.
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He, Jianfeng, and 贺剑锋. "A comparative study on the accessibility of high-speed rail in YangtzeRiver Delta, China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B48183544.
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During the past decade, the high-speed rail (HSR) has got momentum in China, and a number of lines have been put into operation. However, it is noted that the HSR development in China is quite different from that in other regions. The discrepancies are mainly embodied in the duality of HSR types, the diversity of station locations, and the mixed-speed and cross-rail-type train running scheme. These characteristics have considerable impacts on the HSR stations in terms of the external accessibility in the HSR network as well as the internal accessibility in the cities.
Based on the comparative study on the accessibility of main HSR stations in Yangtze River Delta, it is discovered that compared with the conventional rail (CR), the HSR has significantly improved the external accessibility of various cities. It is also found that the HSR has further enhanced the hub status of big cities in the rail network, while the differences among the other cities have been reduced, since the small cities have benefited much more from the HSR than the medium cities. Besides, introducing a new HSR line would improve the external accessibility of cities not only in the HSR network but also in the CR network, due to substantial increases in the efficiency of the whole rail system. In terms of the internal accessibility, it is found that the location choice of stations has significant impacts on the accessibility of HSR stations in cities, and the newly built stations have much lower accessibility due to their remote locations and the under-developed transport facilities and services connecting to them. Overall, for a complete journey by the HSR, the improvement in the external accessibility has made the internal accessibility of HSR stations more critical and sensitive. In this sense, more efforts should be paid to improve the urban transport system so as to fully utilize the positive effects brought about by the HSR.published_or_final_version
Transport Policy and Planning
Master
Master of Arts in Transport Policy and Planning
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Askey, Shumei Yin. "Design and evaluation of decision aids for control of high-speed trains : experiments and model." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/38070.
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Karthikeyan, Bindu Kumar. "Tribo-dynamics of high speed precision spindle bearings." Thesis, Loughborough University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.547399.
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Mutlu, Gunduz. "Dynamic Investigation And Rehabilitation Of Existing Railway Truss Bridge Under High Speed Train Loadings For Passenger Comfort." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609383/index.pdf.
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In Turkey, big investments are made to improve the existing train lines for use of new high speed trains. Most of the bridges on the existing train lines are typical and in this thesis one of the standard types, the classic steel truss bridge is investigated. This thesis presents the dynamic investigation of standard type existing truss bridge for passenger comfort criteria under the high speed train loadings. Two different computational analysis models have been developed to idealize the vehicle-bridge modeling to evaluate the passenger comfort that were influenced by dynamic vibrations on bridges induced by trains. Field tests of this bridge have been conducted by two separate institutes, Middle East Technical University and Turkish State Railways, to determine the state of the bridge under existing low-speed train loadings. Eigenvalue and Time history analysis of the LARSA 4D structural analysis program has been used to investigate the vehicle bridge interactions. The solutions obtained from the analysis have been evaluated with the experimental results. Different rehabilitation options are analytically studied to improve the serviceability of standard steel truss bridges per Eurocode 1990:2002, Eurocode 1991-2:2003, UIC 774-3 and UIC 776-1. The focus of this research is to define a relationship between span weight per meter and passenger comfort as well as the stiffness of this type of bridge.
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Sjöholm, Mikael. "Benefits of regenerative braking and eco driving for high-speed trains : Energy consumption and brake wear." Thesis, KTH, Spårfordon, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31701.
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on mechanical brakes. The electric regenerative brakes can thus be used as normal service brake with minimum time loss.The first part of the study aims at developing a method to calculate wear on train brake pads. This is done by using a reformulated version of Archard’s wear equation with a temperature dependent wear coefficient and a temperature model to predict the brake pad temperature during braking. The temperature model is calibrated using trustworthy data from a brake system supplier and full-scale test results.By performing simulations in the program STEC (Simulation of Train Energy Consumption), energy consumption for different cases of high-speed train operations is procured and significant data for the wear calculations are found. Simulations include both “normal driving techniques” and “eco driving”. The driving styles were decided through interviews with train drivers and experts on energy optimized driving systems.The simulations show that more powerful drive systems reduce both energy consumption and travel time by permitting higher acceleration and energy regeneration while braking. Calculations show that since the electric motors could carry out more of the braking the wear of the mechanical brakes becomes lower.Eco driving techniques can help to further reduce the energy consumption and mechanical brake wear. This driving style can require some time margins though, since it takes slightly longer time to drive when using coasting and avoiding speed peaks. However, if used properly this should not have to affect the actual travel time, partly because some time margins are always included in the timetable.Even if new, more powerful, trains would have the ability to reduce energy consumption and brake wear it is also necessary to have an appropriate slip control system for the electric brakes, making it possible to use them also under slippery conditions. In this context it is important that the adhesion utilization is modest, about 12 – 15 % for speeds up to 100 km/h and lower at higher speeds.
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Sayeed, Md Abu. "Design of ballasted railway track foundations using numerical modelling with special reference to high speed trains." Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/796.
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A new design method for ballasted railway track foundations was developed based on improved empirical models and sophisticated three-dimensional finite element numerical analyses. The method was developed in the form of simple design charts for use by practitioners. The results obtained from the method were found to be in an excellent agreement with the field observations, and the method is expected to provide a significant contribution to the current railway tack design code of practice.
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Hui, Pik-kwan, and 許碧君. "An appraisal of community engagement in planning the express raillink." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B4818357X.
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Community engagement (CE) is an emerging concept with various definitions and acclaimed benefits. It became vital in the transport planning process because conventional approaches to transport planning no longer satisfy a diverse public and is required to improve the “quality of planning outcomes” (Booth and Richardson 2001, p. 148). Since Hong Kong will continue making railway the backbone for passenger transport, and very little (if any) community engagement has been explored for the city’s railway projects, this research aimed to appraise the role, adequacy, and effectiveness of CE in planning Hong Kong’s section of the high-speed Guangzhou-Shenzhen-Hong Kong Express Rail Link from years 2000 to 2010.
Four objectives are pursued, which are to: (1) identify what community engagement (CE) means to the XRL project stakeholders, including their perceptions of CE strengths, weaknesses, and challenges during the XRL‘s planning process of Hong Kong‘s section; (2) identify major factors that shape the XRL project stakeholder understanding and perception of CE; (3) identify and evaluate the implications and the cause and effect that result from stakeholders’ understanding and perception of CE in planning Hong Kong‘s XRL section; and (4) identify scopes to improve the CE process for the city’s future transport infrastructure projects. The study first conducted a literature review. It then traced the development of CE in Hong Kong, particularly in the transport planning realm. News articles, MTR website on the XRL, and policy papers from the Legislative Council Policy Database were examined. A survey was distributed afterwards. 130 usable surveys were returned giving a 40.6% response rate. Results were then quantitatively analyzed with Spearman’s correlation and a two-tailed test. A member from each stakeholder group was lastly interviewed.
Overall, CE improved since British rule, but its extent in planning the XRL fell short or according to Sheedy (2008), non-existent, thus making it ineffective in achieving CE benefits. By statute and the railway development process that professionals adhere to, genuine CE (or higher levels of it) are not encouraged nor guaranteed. Consequences include public resistance and protests after gazettal; respondents believing the government and MTR engagement efforts raised communities ‘buy-in’ of ‘pre-approved plans;’ “sometimes” disrespected and/or mistrusted their communities; “slightly” shared final decision-making with their communities; “sometimes” if not “always” used too much professional jargon; and only “slightly” to “sometimes” followed-up with communities after engaging them in the planning process. The CE concept in Hong Kong is not eminent either. Engaging people in the XRL planning process additionally showed no direct and comprehensive citizen involvement. This is probably due to the general public and government attitudes, which makes it challenging for genuine CE to occur on top of limited resources. On the bright side, many CE benefits were found true from descriptive analysis, and electronic media was deemed the most effective tool to engage citizens. From quantitative analysis, a stakeholder’s power and/or knowledge lacked a statistical significant relationship with how satisfied he or she was on how CE was conducted in XRL planning and his or her perceptions of it. A stakeholder’s exposure to CE, however, mostly had a negative statistically significant relationship with a few perceptions of community engagement.
In the end, three major recommendations are offered to improve CE in Hong Kong’s transport planning framework. In no order of importance, the general community and XRL Sponsor (government and MTR) must change their attitude towards engagement. The XRL Sponsor must aggressively educate the general Hong Kong community about community engagement. Lastly, it should revise the Railways Ordinance to incorporate more CE characteristics.published_or_final_version
Transport Policy and Planning
Master
Master of Arts in Transport Policy and Planning
47
Lam, Kwun-yi. "The prospects of Maglev for Hong Kong's railway development." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk:8888/cgi-bin/hkuto%5Ftoc%5Fpdf?B23339159.
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Forooqi, A. Masood. "Ridership studies for the proposed Florida high speed rail system." FIU Digital Commons, 1990. http://digitalcommons.fiu.edu/etd/3254.
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Florida, the fourth largest and sunshine state, is growing at the rate of 800 new residents daily.!! By the year 2000 the population is estimated to be 16 Million, and the annual tourists at 80 Million, generating 40 Million trips.
The proposed High Speed Rail will connect Miami and West Palm Beach to Orlando and Tampa. This 325-mile corridor represents 70 % of all the "Socio-Economic Resources" of the whole of Florida and the trend will continue well into the next century. The Miami-Orlando ride will reduce to 2 hours speeding at up to 150 mph. It will be operational by 1995 and the system is estimated to cost 4.6 Billion Dollars.
One of the major problems encountered by the new High Speed Rail (HSR) is the "RIDERSHIP FORECASTING," In the United States there is a lack of current information about the Total Volume of Intercity Trips and the Specific Characteristics of the Trips that determines a willingness to use HSR. The Quality, Comprehensiveness, and Acceptability, by the forecasts must be sufficient to generate Public Support, Confidence, and Response for the Implementation of HSR.
The THESIS discusses the various Ridership Forecasting Techniques and chooses the “Most Suitable Model” applicable to conditions in South and Central Florida.
A “Model Choice Based Model” is selected called, “THE LOGIT FUNCTION”, which takes into account, the Floridian Choice of available Travel Modes, and the Factors Affecting the Manner of the “Decision making Process”, in Favour of a Particular Mode. Evaluating Business and Non-Business Travel for the Internal Trips, (including the Induced Demand and the Short Trips) and the External Trips. The External and Short Trips were Not considered by Previous Studies. The standard guidelines for “Revenue and Ridership Forecasting,” by High Speed Rail Association are closely followed in this Study. Due consideration is also given to Socio-Economic data involving population, wealth, average per capita income, number of families, size of labor force, number of hotel / motel rooms and college enrollment. A Survey was carried out, to collect the data and to test the Sensitivity, under given set of conditions and scenarios.
The studies conclude that HSR is a Feasible Project and by the year 2000, the Ridership will be 3.8 Million Annual Trips. The future studies will continue to improve the results, as an individual’s attitude and response towards HSR Travel becomes better known and recorded in Florida
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Kastner, Jeffrey F. "Far-field radiated noise mechanisms in high reynolds number and high-speed jets." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1181753004.
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Wang, Chenxin. "Dynamics of High-Speed Planetary Gears with a Deformable Ring." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/103008.
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This work investigates steady deformations, measured spectra of quasi-static ring deformations, natural frequencies, vibration modes, parametric instabilities, and nonlinear dynamics of high-speed planetary gears with an elastically deformable ring gear and equally-spaced planets.
An analytical dynamic model is developed with rigid sun, carrier, and planets coupled to an elastic continuum ring. Coriolis and centripetal acceleration effects resulting from carrier and ring gear rotation are included. Steady deformations and measured spectra of the ring deflections are examined with a quasi-static model reduced from the dynamic one. The steady deformations calculated from the analytical model agree well with those from a finite element/contact mechanics (FE/CM) model. The spectra of ring deflections measured by sensors fixed to the rotating ring, space-fixed ground, and the rotating carrier are much different. Planet mesh phasing significantly affects the measured spectra. Simple rules are derived to explain the spectra for all three sensor locations for in-phase and out-of-phase systems. A floating central member eliminates spectral content near certain mesh frequency harmonics for out-of-phase systems.
Natural frequencies and vibration modes are calculated from the analytical dynamic model, and they compare well with those from a FE/CM model. Planetary gears have structured modal properties due to cyclic symmetry, but these modal properties are different for spinning systems with gyroscopic effects and stationary systems without gyroscopic effects. Vibration modes for stationary systems are real-valued standing wave modes, while those for spinning systems are complex-valued traveling wave modes. Stationary planetary gears have exactly four types of modes: rotational, translational, planet, and purely ring modes. Each type has distinctive modal properties. Planet modes may not exist or have one or more subtypes depending on the number of planets. Rotational, translational, and planet modes persist with gyroscopic effects included, but purely ring modes evolve into rotational or one subtype of planet modes. Translational and certain subtypes of planet modes are degenerate with multiplicity two for stationary systems. These modes split into two different subtypes of translational or planet modes when gyroscopic effects are included.
Parametric instabilities of planetary gears are examined with the analytical dynamic model subject to time-varying mesh stiffness excitations. With the method of multiple scales, closed-form expressions for the instability boundaries are derived and verified with numerical results from Floquet theory. An instability suppression rule is identified with the modal structure of spinning planetary gears with gyroscopic effects. Each mode is associated with a phase index such that the gear mesh deflections between different planets have unique phase relations. The suppression rule depends on only the modal phase index and planet mesh phasing parameters (gear tooth numbers and the number of planets).
Numerical integration of the analytical model with time-varying mesh stiffnesses and tooth separation nonlinearity gives dynamic responses, and they compare well with those from a FE/CM model. Closed-form solutions for primary, subharmonic, superharmonic, and second harmonic resonances are derived with a perturbation analysis. These analytical results agree well with the results from numerical integration. The analytical solutions show suppression of certain resonances as a result of planet mesh phasing. The tooth separation conditions are analytically determined. The influence of the gyroscopic effects on dynamic response is examined numerically and analytically.Doctor of Philosophy