Tesis por compendio / [ES] El ruido de rodadura de vehículos ferroviarios presenta importantes desafíos en entornos urbanos y suburbanos, siendo precisa una comprensión integral de sus mecanismos subyacentes para una mitigación efectiva. Esta Tesis ofrece una investigación exhaustiva sobre la generación de ruido de rodadura, tanto en vías rectas como curvas, a través del desarrollo de modelos avanzados de alta frecuencia y herramientas de cálculo para una rigurosa predicción de niveles de ruido. El ruido de rodadura surge de la interacción entre las ruedas y los carriles en presencia de imperfecciones en sus superficies de contacto. Los principales componentes ferroviarios que contribuyen a la emisión acústica son las traviesas, los carriles y las ruedas. Las traviesas y los carriles están conectados por medio de las placas de asiento, mientras que las ruedas y los carriles están dinámicamente acoplados a través de su contacto. En consecuencia, cambios en cualquier componente pueden afectar al comportamiento dinámico y acústico del resto, subrayando la necesidad de un modelo integral para abordar eficazmente la radiación por ruido de rodadura. En esta Tesis se exploran y desarrollan diferentes modelos dinámicos de la vía y del eje montado. La vía, que se asume infinita, se describe utilizando la teoría de estructuras periódicas y se caracteriza por sus números y formas de onda. El eje montado se modeliza mediante el Método de Elementos Finitos y se caracteriza por sus frecuencias naturales y modos de vibración. La interacción rueda/carril se describe como una relación linealizada entre el movimiento relativo de ambos componentes y las fuerzas de contacto. Cabe indicar que los modelos explorados en este trabajo están formulados en el dominio de la frecuencia. Asimismo, se realiza un estudio de influencia del diseño de la vía en la radiación por ruido de rodadura, cuantificando los parámetros contribuyentes a la emisión acústica mediante técnicas estadísticas. Los resultados apuntan a que la geometría del carril tiene un impacto limitado en la radiación, mientras que las propiedades viscoelásticas de la vía, en particular la rigidez de la placa de asiento, desempeñan un papel fundamental en la generación de ruido. Es remarcable que, entre los distintos diseños, se han encontrado variaciones de hasta 7,4 dB(A) en la radiación acústica. Durante el desarrollo de esta investigación, se ha prestado atención al modelizado del eje montado. Su rotación se incluye usando coordenadas Eulerianas, lo que resulta un enfoque conveniente ya que el punto de contacto de la rueda con el carril permanece en una posición espacial constante. Dada la simetría axial de su geometría, la respuesta dinámica del eje montado se expande a lo largo de la dirección circunferencial mediante series de Fourier, lo que permite formular el comportamiento dinámico y acústico de este cuerpo tridimensional (3D) en un marco bidimensional (2D), resolviendo analíticamente la coordenada circunferencial. Esta metodología ofrece sin pérdida de generalidad una reducción del tiempo de cálculo computacional, lo que hace que el modelo sea idóneo para su integración en algoritmos de optimización. Por último, se realiza una investigación pionera sobre el ruido de rodadura cuando el vehículo negocia una curva. Si bien la curva está generalmente asociada con el ruido por chirridos, esta Tesis explora y confirma la importancia que también tiene el ruido de rodadura en estas condiciones. Para ello, se modelizan los efectos inerciales y giroscópicos que sufre un eje montado al describir una trayectoria curva. Además, diferentes fenómenos complejos que ocurren en el contacto rueda/carril, como por ejemplo el movimiento relativo entre estos elementos, se incorporan en el modelo de interacción. Los resultados indican que la posición del contacto rueda/carril sirve como un buen indicador del impacto que la negociación de una curva tiene en el ruido de rodadura. / [CA] El soroll de rodament de vehicles ferroviaris presenta importants reptes en entorns urbans i suburbans, requerint una comprensió integral dels seus mecanismes subjacents per a una mitigació efectiva. Aquesta Tesi ofereix una investigació exhaustiva sobre la generació de soroll de rodament, tant en vies rectes com corbes, mitjançant el desenvolupament de models avançats d'alta freqüència i eines de càlcul per a la rigorosa predicció dels nivells de soroll radiat. El soroll de rodament sorgeix de la interacció entre les rodes i els carrils en presència d'imperfeccions en les seues superfícies de contacte. Els principals components ferroviaris que contribueixen a l'emissió acústica són les travesses, els carrils i les rodes. Les travesses i els carrils estan connectats a través de les plaques d'assentament, mentre que les rodes i els carrils estan acoblats mitjançant la seua interacció. En conseqüència, canvis en qualsevol component poden afectar al comportament dinàmic i acústic de la resta, subratllant la necessitat d'un model integral. En aquesta Tesi s'exploren i desenvolupen diversos models dinàmics de la via i de l'eix muntat. La via, que es considera infinita, es descriu utilitzant la teoria d'estructures periòdiques i es caracteritza pels seus números i formes d'ona. L'eix muntat es modelitza mitjançant el Mètode d'Elements Finits i es caracteritza per les seues freqüències naturals i modes de vibració. La interacció entre l'eix muntat i la via es descriu com una relació linealitzada entre el moviment relatiu d'ambdós components i les forces de contacte. Cal assenyalar que els models explorats en aquest treball estan formulats en el domini de la freqüència. Així mateix, es realitza un estudi d'influència del disseny de la via en la radiació, quantificant els paràmetres contribuents a l'emissió acústica mitjançant tècniques estadístiques. Els resultats apunten que la geometria del carril té un impacte limitat en la radiació sonora, mentre que les propietats viscoelàstiques de la via, en particular la rigidesa de la placa d'assentament, tenen un paper fonamental en la generació de soroll. És destacable que, entre els diferents dissenys, s'han trobat variacions de fins a 7,4 dB(A) en la radiació per soroll de rodament. Durant el desenvolupament d'aquesta investigació, s'ha prestat atenció al modelatge de l'eix muntat. La seua rotació s'inclou en la formulació utilitzant coordenades Eulerianes, la qual cosa resulta un enfocament convenient ja que el punt de contacte de la roda amb el carril roman en una posició constant. Donada la simetria axial de la seua geometria, la resposta dinàmica de l'eix muntat s'amplia al llarg de la direcció circumferencial mitjançant sèries de Fourier, permetent formular el comportament dinàmic i acústic d'aquest cos tridimensional (3D) en un marc bidimensional (2D), i resolent la coordenada circumferencial analíticament. Aquesta metodologia ofereix sense pèrdua de generalitat una reducció del temps de càlcul computacional, la qual cosa fa que el model siga idoni per a la seua integració en algoritmes d'optimització. Finalment, es realitza una investigació pionera sobre el soroll de rodament quan el vehicle negocia una corba. Si bé la corba està generalment associada amb el soroll per grinyols, aquesta Tesi explora i confirma la importància que també té el soroll de rodament en aquestes condicions. Per a això, es modelitzen els efectes inercials i giroscòpics que pateix un eix muntat al descriure una trajectòria corba. A més, diferents fenòmens complexes que ocorren en el contacte roda/carril, com el moviment relatiu entre aquests elements, s'incorporen en el model d'interacció. Els resultats indiquen que la posició del contacte roda/carril serveix com un bon indicador de l'impacte que la negociació d'una corba té en el soroll de rodament. / [EN] Rolling noise emission in railway systems presents significant challenges in urban and suburban environments, requiring a comprehensive understanding of its underlying mechanisms for effective mitigation. This Thesis offers a thorough investigation into rolling noise generation, considering both tangent and curved tracks, through the development of advanced high-frequency models and calculation tools to predict noise levels accurately. Rolling noise arises from the interaction between railway wheels and tracks in the presence of roughness on their contact surfaces. The principal components contributing to the acoustic emission are the sleepers, rails, and wheels. Sleepers and rails are interconnected through rail pads, while wheels and rails are dynamically coupled due to their contact. Consequently, changes in any component might impact the dynamic and acoustic behaviour of all of them, outlining the necessity of a comprehensive model to address rolling noise radiation effectively. Various models for the track and wheelset are explored and developed in this Thesis. The track, assumed to be infinite, is described using periodic structure theory and it is characterised by its wavenumbers and waveshapes. The wheelset is modelled through the Finite Element Method (FEM) and it is characterised by its natural frequencies and vibration modes. The wheelset and track interaction is described as a linearised relationship between the relative motion of both components and the contact forces. The models examined in this work are formulated in the frequency domain. Identified track properties influencing rolling noise radiation are quantified using statistical techniques. While the rail geometry is found to have a limited impact on the total radiation, the viscoelastic properties of the track, particularly the rail pad stiffness, play a crucial role in noise generation. Variations up to 7.4 dB(A) were observed for different track designs. Special attention is devoted to the wheelset modelling in this Thesis. Its rotation is considered using Eulerian coordinates, a convenient approach as the wheel contact point with the rail remains at a constant spatial position. Given the axial symmetry of its geometry, the wheelset dynamic response is expanded around the circumferential direction using Fourier series, which yields a two-dimensional (2D) formulation of the dynamic and acoustic behaviour of this three-dimensional (3D) system, with the circumferential coordinate being solved analytically. This methodology, denoted as axisymmetric approach, offers a significant reduction in the associated computational calculation time while preserving accuracy, making the model well suited for its integration into optimisation algorithms. Lastly, a novel investigation into rolling noise when the vehicle negotiates a curve is conducted. While curved tracks are generally associated with squeal noise, this Thesis offers valuable insights into the importance of rolling noise as well. To achieve this, the inertial and gyroscopic effects associated with a wheelset running on a curve are modelled. Complex phenomena occurring at the wheel/rail contact, such as the relative motion between these two elements, are incorporated into the interaction model. The results indicate that the wheel/rail contact position serves as a reliable indicator of the impact of a curve on the rolling noise. / This Thesis has been supported by Ministerio de Ciencia, Innovación y Universidades in the framework of the FPU grant program. Grants FPU18/03999, EST21/00213, and EST22/00353 as well as projects TRA2017-84701-R, PID2020-112886RA-I00, and PID2023-148483OB-I00 funded by MCIN/AEI/10.13039/501100011033, “ESF Investing in your future”, and “ERDF A way of making Europe” are acknowledged. The author also expresses his gratitude for the support provided by Programa PROMETEO/2021/046 of Generalitat Valenciana. / Andrés Ruiz, VT. (2024). Comprehensive dynamic models of railway wheelsets and tracks for the prediction of rolling noise [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/206074 / Compendio

The wheel-rail contact is at the core of all research related to vehicletrackinteraction. This tiny interface governs the dynamic performanceof rail vehicles through the forces it transmits and, like any high stressconcentration zone, it is subjected to serious damage phenomena. Thus,a clear understanding of the rolling contact between wheel and rail is keyto realistic vehicle dynamics simulation and damage analysis. In a multi-body dynamics simulation, the demanding contact problemshould be evaluated at about every millisecond for several wheel-rail pairs.Hence, a rigorous treatment of the contact is highly time-consuming.Simplifying assumptions are therefore made to accelerate the simulationprocess. This gives rise to a trade-o between the accuracy and computationaleciency of the contact model in use. Conventionally, Hertz+FASTSIM is used for calculation of the contactforces thanks to its low computational cost. However, the elliptic patchand pressure distribution obtained by Hertz' theory is often not realisticin wheel-rail contact. Moreover, the use of parabolic traction bound inFASTSIM causes considerable error in the tangential stress estimation.This combination leads to inaccurate damage predictions. Fast non-elliptic contact models are proposed by others to tacklethis issue while avoiding the tedious numerical procedures. The studiesconducted in the present work show that the accuracy of these models iscase-dependent. To improve the accuracy of non-elliptic patch and pressure estimation,a new method is proposed. The method is implemented in an algorithmnamed ANALYN. Comparisons show improvements in patch and, particularly,pressure estimations using ANALYN. In addition, an alternative to the widely-used FASTSIM is developed, named FaStrip. Unlike FASTSIM, it employs an elliptic traction boundand is able to estimate the non-linear characteristic of tangential stressdistribution. Comparisons show more accurate estimation of tangentialstress and slip velocity distribution as well as creep forces with FaStrip. Ultimately, an ecient non-elliptic wheel-rail contact model consistingof ANALYN and FaStrip is proposed. The reasonable computationalcost of the model enables it to be used on-line in dynamics simulationand its accuracy can improve the damage predictions. / <p>QC 20160202</p>

Research in radiotherapy for cancer treatment focuses on finding methods that can improve the compromise between tumour cell inactivation versus damage to the surrounding healthy tissue. As new radiation modalities such as proton therapy become accessible for everyday clinical practice, a better understanding of the variation in biological response of the tumour and healthy tissues would improve treatment planning to achieve optimal outcome. The development of radiobiological models capable of accurate predictions of biological effectiveness is needed. Existing radiation quality descriptors such as absorbed dose and LET are insufficient to explain variation in biological effectiveness for different treatment modalities. The stochastic nature of ionizing radiation creates discrete patterns of energy deposition (ED) sites which can now be analysed through sophisticated computer simulations (e.g. Monte Carlo track structure codes). This opens the possibility to develop a nanometre characterization of radiation quality based on the spatial cluster patterns of ED. The aim of this thesis is to investigate the track structure (ED spatial pattern) properties of several radiation qualities at a micro- and nanometric scale while exploring their influence in biological response through correlations with published experimental data. This work uses track structure data simulated for a set of 15 different radiation qualities: 4 commonly used brachytherapy sources, 6 different proton energies, 4 different carbon ion energies, and 60Co photons used as reference radiation for quantification of biological effectiveness. At a micrometre level, the behaviour of the microdosimetric spread in energy deposition for target sizes of the order of cell nuclei was analysed. The degree of the influence it had in the biological response was found to be negligible for photon sources but for protons and carbon ions the impact increased with decreasing particle energy suggesting it may be a confounding factor in biological response. Finally, this thesis outlines a framework for modelling the relative biological effectiveness based on the frequency distribution of cluster order as a surrogate for the nanometre classification for the physical properties of radiation quality. The results indicate that this frequency is a valuable descriptor of ionizing radiation. The positive correlation across the different types of ionizing radiation encourages further development of the framework by incorporating the behavior of the microdosimetric spread and expanding tests to other experimental datasets.

The Swedish Transport Administration has been giving the task to set up a new standard for concrete slabs for the new high-speed railway in Sweden. They are demanding that the concrete slabs must be dimensioned according to the German Beton Kalender 2000. This report will explore the results when dimensioning a slab track, according to the German Beton Kalender 2000. Moment capacity, deformation, and crack width are calculated according to two structural theories, namely slab and beam theory, and a comparison between the two methods is presented.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / Magnetic tape is the primary medium used to capture and store unprocessed data from remote sensing satellites. Recent advances in digital cassette recording technology have resulted in the introduction of a range of data recorders which are equally at home working alongside conventional recorders or as part of more advanced data capture strategies. This paper shows how users are taking advantage of the convenience, economy and efficiency of this new generation of cassette-based equipment in a range of practical applications.

Thesis (PhD (Sport Sc)) -- University of Stellenbosch, 2004. / ENGLISH ABSTRACT: This study investigated the effects of a relaxation, self-talk, goal-setting, imagery, and concentration training package on the performance of six athletes in the 1500- meter event. Subjects were four female and two male high school middle distance athletes. The dependent measure was time taken to complete the 1500-meter nm in competition settings. A mental skills training package was developed, implemented and evaluated using a single subject, multiple baseline design. Performance scores were plotted for each 1500-meter nm and subjects' graphs were assessed for intervention-related change against mean performance change and established split-middle analysis criteria. Visual inspection of plotted values was supplemented by quantitive analysis using repeated measures analysis of variance (RANOV A). This study also included procedural reliability checks to ensure that the athletes did in filet utilize the mental skills they received training in. Visual analysis indicated the mental skills package to be effective in enhancing performance times (1500-meter) in the case of four of the athletes. Overall, repeated measures analysis of variance revealed significant improvement in 1500- meter performance times for subjects across phases. However, a split-middle analysis of within subject variation indicated that a significant intervention effect was not observed in two of the six subjects. The social validity assessment by athletes and their two coaches provided further confirmation of the overall effectiveness of the intervention. Social validation checks indicated all participants to have perceived the intervention to be successful and all were satisfied with the delivery and content of the training package. The results support the usefulness of single-subject research designs for assessing the impact of mental training. The present study demonstrated that a mental skills training package combining relaxation, self-ta1k, goal setting, imagery, and concentration skills was effective in enhancing athletic performance. / AFRIKAANSE OPSOMMING: Die effek van "n sportsielkundige opleidingspakket, bestaande uit ontspanningsvaardighede, effektiewe selfspraak, doelwitstelling, beelding en konsentrasievaardighede op die prestasie van sportlui in die 1500-meter wedloop, is in die onderhawige navorsing ondersoek. Die proefpersone wat aan die navorsingprojek deelgeneem het, was vier vroulike en twee manlike hoërskool middelafstand-atlete. Die afhanklike veranderlike is gedefinieer as die tyd wat dit elke proefpersoon neem om die 1500-meter wedloop in kompetisie-situasies te voltooi. 'n Sportsielkundige opleidingspakket is ontwikkel, geïmplementeer en die effek daarvan op prestasietyd is geëvalueer deur gebruik te maak van "n enkelproefpersoon-, meervoudige basislynontwerp oor individue. Wedlooptyd in die 1500- meter is graftes ten opsigte van elke proefpersoon voorgestel en volgens kriteria vir visuele inspeksie en die "split-middle" -tegniek geanaliseer. Visuele analise van die data is deur middel van kwantitatiewe herhaalde waameming;analise van die variansie uitgebrei. Die ondersoek het ook kontrole vir prosedurelebetroubaarheid ingesluit om te verseker dat die betrokke sportsielkundige vaardighede waarin proefpersone opgelei is, inderdaad deur hul gebruik word Visuele analise van die navorsingdata het aangedui dat die sportsielkundige opleidingsprogram wel effektiefwas om presf.asietyd (l500-meter) by vier van die ses atlete te verbeter. Die herhaalde waamemingsanalise van die variansie het oor die algemeen beduidende verbetering in presf.asietyd in die 1500-meter vir proefpersone vanaf die basislyn:fase na die intervensiefase aangetoon. "n "Split-miádle" analise van intra-proefpersoon variasie het egter aangedui dat "n beduidende intervensie-effek nie by twee van die ses proefpersone waargeneem kon word nie. 'n Gunstige sosiale validering is van die betrokke proefpersone en hul afrigters ontvang wat verdere bevestiging bied vir die effektiwiteit van die intervensie oor die algemeen. Resultate met betrekking tot die sosiale validering het aangedui dat al die deelnemers by die navorsingprojek die intervensie as suksesvol beskou het en tevrede was met die toepassing en inhoud van die opleidingspakket. In die onderhawige ondersoek is aangedui dat "n sportsielkundige opleidingsprogram wat ontspanningsvaardighede, selfspraak, doelwitstelling, beelding en konsentrasievaardighede kombineer, weloor die algemeen effektief was om sportlui se prestasie te verbeter.

Since 1988, the states of Armenia and Azerbaijan have been engaged in conflict over the enclave of Nagorno Karabakh. The conflict has developed into one of the most intractable and complicated disputes in the international arena, with the main parties being the two rivalling sovereign states plus the 'unrecognised state' of Nagorno Karabakh. Despite the optimistic statements and claims by the OSCE and after many years of negotiations and talks, the peace process remains in stalemate. The research argues the virtues of Track Two diplomacy and highlights the successful instances where it has made important contributions to the 'official' or Track One diplomatic process. It also explores the potential of a 'no war no peace' situation by discerning the factors influencing the progress of the conflict. The research shows that a deeper understanding of the obstacles to peace is achieved by appreciating the significance of historical events as well as recognising the motives and interests of the different parties. The study reviews all major factors which have led to the failure of resolution efforts, particular the negative role played by Russia. It concludes that the scholars in the field of conflict resolution can bring about a lasting peace to this region, provided there is a fundamental change in the structure of the co-chairs of the OSCE.

Repeat track analysis is one tool that can be used to derive parameters describing elevation changes from elevation data collected from a satellite with a near-repeat groundtrack. While initially developed to study ocean topography, it was then applied to ice sheet data. This study expands upon that previous research by testing the method’s ability to estimate parameters using different amounts of data, different grid sizes and types, and different elevation models containing different parameters to be estimated. In all cases, ICESat-derived elevations were used as input data, as ICESat has a near-repeat groundtrack with extensive coverage of the Greenland and Antarctica ice sheets. Results were compared using the differences between modeled and ICESat-derived elevations, correlation of estimated parameters to known physical features, and differences between known and estimated parameter values for simulated elevation data. It was found that there should be data from at least as many distinct time periods (or, in the case of ICESat, laser campaigns) as parameters being estimated, grids centered on and aligned with the reference groundtrack should be used, and that elevation models containing a constant elevation change rate, slopes, an initial elevation at the grid center, and annual terms should be used. Crossover analysis is a different method to determine elevation change rate with elevation data and serves as an independent verification of the repeat track analysis method. It was found that the hdot values determined from crossover and repeat track analyses agreed to within 5 cm/yr in most areas of the ice sheets, with differences greater than 40 cm/yr along the coasts. While repeat track analysis provides greater coverage than crossover analysis, it is uncertain which method provides the most accurate results. / text

<p>Active secondary suspension in trains has been studied for a number of years, showing promising improvements in ride comfort. However, due to relatively high implementation and maintenance costs, active technology is not being used in service operation to a large extent. The objective of this study is to develop an active lateral secondary suspension concept that offers good ride comfort improvements and enables centring of the carbody above the bogies when negotiating curves at unbalanced speed. Simultaneously, the active suspension concept should be a cost-effective solution for future series production. The thesis consists of an introductory part and three appended papers.</p><p>The introductory part describes the concept of active secondary suspension together with different actuator types and control methods. Further, the present simulation model and applied comfort evaluation methods are presented. The introductory part also comprises a summary of the appended papers, an evaluation of track forces and suggestions for further work.</p><p>Paper A presents the initial development of an active lateral secondary suspension concept based on sky-hook damping in order to improve vehicle dynamic performance, particularly on straight tracks. Furthermore, a Hold-Off-Device (HOD) function has been included in the suspension concept in order to centre the carbody above the bogies in curves and hence avoid bumpstop contact. Preparatory simulations as well as the subsequent on-track tests in the summer of 2007 showed that the active suspension provides improved passenger ride comfort and has significant potential to be a cost-effective solution for future implementation.</p><p>In Paper B, measurement results from on-track tests performed in 2008 are presented. The active secondary suspension concept was slightly modified compared to the one presented in the first paper. One modification was the implementation of a gyroscope in order to enable detection of transition curves and to switch off the dynamic damping in these sections. Ride comfort in the actively suspended carbody was significantly improved compared to that in the passively suspended car. The satisfactory results led to implementation of the active suspension system in long-term tests in service operation in the beginning of 2009.</p><p>In Paper C, a quarter-car model in MATLAB has been used to investigate a more advanced control algorithm: <em>H</em>_∞ instead of sky-hook. <em>H</em>_∞ control provides more flexibility in the design process due to the possibility to control several parameters. In particular, this is done by applying weight functions to selected signals in the system. When comparing the two control strategies through simulations, the results show that <em>H</em>_∞ control generates similar carbody accelerations at the same control force as sky-hook; however, the relative displacement displacement is somewhat lower.</p>

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