1,720,953 research outputs found
Ingegoten spoor op bruggen: Onderzoek naar prestatieverbeteringen voor verlengen van levensduur en snellere reparatie van ingegoten spoor op bruggen
No full textIn dit verslag wordt een alternatieve uitvoering gezocht voor de intensieve reparatiewerkzaamheden van ingegoten spoorstaaf constructies op stalen spoorbruggen. Gedurende het onderzoek is informatie ingewonnen door gesprekken met verschillende bedrijven. Allereerst is gesproken met ProRail over de problematiek en de probleemstelling. Vervolgens heeft een gesprek plaatsgevonden met het bedrijf Edilon)(Sedra welke de ontwikkelaar is van het ingegoten spoor en de wereldwijd marktleider hierin is. Ook is gesproken met aannemer StruktonRail over de reparatie en uitvoering van ingegoten spoor op de Moerdijkbrug. Op deze manier is een volledig beeld gevormd van de problemen en mogelijkheden. Er is geprobeerd om een onafhankelijk standpunt in te nemen waardoor zowel in gesprek is gegaan met de opdrachtgever en spoorbeheerder (ProRail), de ontwikkelaar en verkoper van het ingegoten spoor (Edilon)(Sedra en de aannemer StruktonRail. De aanbevelingen zijn zowel voor het veranderen van de probleemsituatie die nu voorkomt op huidige constructies, maar is vooral ook bedoelt als aanbeveling voor de constructie van toekomstige kunstwerken. Er wordt een onderscheidt gemaakt in aanbevelingen die uitvoerbaar zijn op de huidige spoorbruggen en op aanbevelingen voor methodes waarvoor extra onderzoek nodig is. De belangrijkste aanbeveling is om het voorgedragen ontwerp te testen voor haalbaarheid in de spoorconstructie.Civil Engineering and GeosciencesStructural EngineeringRailway Engineerin
Wheel/rail interface optimisation
No full textIn this thesis, wheel/rail interface optimisation, and particularly the problems of wheel and rail profile design are considered. The research task pursued by this thesis engenders investigation of a range of problems. First, geometric properties of contact between wheel and rail are investigated. Then, physical properties of rolling contact between wheel and rail are studied with the help of contact mechanics. Railway vehicle dynamics are then considered using multibody dynamic approach. Finally, a numerical optimisation method is used for the design of the wheel profile. All these disciplines are combined in one wheel (rail) profile design procedure. The wheel (rail) profile design procedure is developed with the idea that the rolling radius difference (RRD) function, to a large extent, describes the wheel/rail contact properties. Therefore, for a known optimal RRD function, a wheel profile that delivers the required contact properties defined by this RRD can be determined. Wheel and rail profile measurements are used to analyse wheelset contact properties in order to design the target RRD function. The problem of finding a wheel profile corresponding to the target RRD function is formulated as an optimisation problem. The dynamic performance of a vehicle with the designed wheel profile is tested for stability, wear, and dynamic contact stresses using the ADAMS/Rail computer package. In this research, three railway system types are considered - tram, metro, and conventional railway. Using the developed design procedure, new wheel profiles are designed for each above mentioned case, solving for, respectively, the problems of flange wear, stability (as a result of excessive tread wear), and RCF. In the first two cases, wheel profiles were successfully implemented on the respective networks. Successful application of the design procedure to real-life problems has proven its usability and expediency.Civil Engineering and Geoscience
An inverse shape design method for railway wheel profiles
No full textCivil Engineering and Geoscience
Improvement of train-track interaction in transition zones via reduction of ballast damage
No full textTransition zones in railway tracks are locations with considerable changes in the vertical stiffness of the rail support. Typically they are located near engineering structures, such as bridges, culverts, tunnels and level crossings. In such locations, the differential settlement always exists and continually grows without proper maintenance. Due to the effect of the differential settlement and bending stiffness of the rails, hanging sleepers may exist, which are invisible under ordinary circumstances, but generate high displacements and impact during train passages. Therefore, a method to detect the differential settlement (Or hanging sleepers) of track transition zones is presented, which is combined with numerical simulations and field measurements. The numerical model of the track transition zone developed here uses contact elements for modelling the connection between the sleepers and the ballast, bilinear springs for fastening system and Hertzian spring for wheel-rail interaction. The model is capable for simulating the dynamic behaviour of the transition zones with differential settlement or hanging sleepers. Using the model, the dynamic responses such as the vertical displacement of rail, the dynamic wheel load, the axial stress in rail and the vertical stress of ballast has been be obtained and analysed. The field measurements were performed as well. Using Video Gauge System (VGS) the vertical displacements of rail in the vicinity of a track transition zone were measured. The differential settlement of the measured transition zone was analysed by comparing the measurement and numerical results. Finally, based on the obtained findings and the simulation results some track design improvements and suggestions for maintenance actions are given.Structural EngineeringCivil Engineering and Geoscience
Improvement of train-track interaction in turnouts by optimising the shape of crossing nose
No full textProper rail geometry in the crossing part is essential for reducing damages on the nose rail. A numerical optimisation approach to minimise impact damage and wear in the crossing panel by varying the nose rail shapeis presented in the paper.Theoptimisation formulatedas a weighted multi-objective problemis solved by adapting the Multipoint Approximation Method (MAM).Dynamic vehicle-turnout interaction as a function of crossing geometry is investigated using multi-body simulation method. The optimisation problem has been solved for different sets of weightcoefficients. Afterwards the robustness of the optimumdesigns has been analysed under different vehicle-track system conditions.Structural EngineeringCivil Engineering and Geoscience
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Assessing crossing geometry: Expert tool for numerical and experimental assessment of turnout crossing geometry
No full textThis thesis project discusses the development of a fast assessment tool for the performance of railway turnout crossings. The assessment tool is developed in Matlab and allows the user to swiftly set up a model and assess the performance. The rail geometry input can be either design drawings or in situ measured geometry. This allows the user to compare designed, delivered and deployed crossings. Comparisons are made between several types of 1:9 crossings, by assessing the designs from various countries. The vehicle-track interaction is modelled in the commercial multi-body system (MBS) analysis package VI-Rail. The simulations indicate that the automated workflow provides insights similar to manual modelling, while being much faster. The report ends with recommendations based on the geometry comparisons and simulation results.Civil Engineerin
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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