O expressivo crescimento do setor ferroviário com o processo de privatizações das operações a partir de 1996, fez com que a modalidade aumentasse sua participação na matriz de transportes brasileira. Porém, essa expansão, obtida essencialmente com a substituição e aumento de locomotivas e vagões, juntamente com a modernização do sistema de controle de tráfego, deverá em breve encontrar limites impostos pela geometria e superestrutura da malha ferroviária. O objetivo da dissertação é analisar como esses fatores afetam a capacidade de processamento de trens através de uma linha ferroviária singela. Para alcançar este objetivo desenvolveu-se um modelo capaz de identificar as características da via que restringem as velocidades e o headway das composições ferroviárias. O modelo proposto permite, através da análise de desempenho em cada um dos arcos de um trecho de linha ferroviária, obter uma medida de desempenho global no trecho e identificar os gargalos. O método adotado para determinar a capacidade do trecho para cenários operacionais alternativos é o da utilização de diagramas espaço-tempo. Os diagramas espaço-tempo são elaborados através de um algoritmo em MatLab que soluciona os conflitos nos cruzamentos para um determinado tempo de cruzamento nas estações e efetua a contagem de pares de trens. O desempenho dos trens em cada um dos arcos, dado de entrada do algoritmo, é adquirido através de um modelo de simulação de desempenho de trens elaborado pela Association of Amerian Railroads (AAR). Como aplicação prática apresenta-se uma análise de capacidade para um dos principais corredores de exportação, um trecho da Brasil Ferrovias S.A. entre as cidades de Santa Fé do Sul e Araraquara no estado de São Paulo. A análise dos resultados mostra que o principal fator limitante da velocidade média no espaço dos trens é a atual condição da superestrutura ferroviária e que, uma vez eliminada esta restrição, a supressão de passagens de nível e a relocação de estações de cruzamento, produzem ganhos expressivos. / The expessive growth of the railway sector due to the privatization of the operations since 1996, is increasing the participation of this mode in the brazilian transport matrix. However, this growth is obtained mainly from the replacement and increase of the rolling stock and the modernization of the traffic control system, and will soon reach some important limits imposed by the railway geometry and superstructure. The thesis objective is to analyze how these factors affect the capacity to process trains through a single track railroad line. To reach this objective, a model that identifies the restrictions that impose limits to the speed and headways of the trains was developed. Through the performance analysis on each arc of a railway segment, the model obtains a global performance measure for the whole segment and identifies the bottlenecks. Time-space graphs are developed to determine the capacity of the segment for different operating scenarios. To build the space-time graphs, solve the conflicts at the crossings for a given time to cross and count the trains per day, an algorithm using the MathLab software was developed. The train performance on each arc is obtained through a simulation model developed by the Association of American Railroads (AAR). As a practical application, a capacity analysis of one of the most important export corridors is presented, a segment of the Brasil Ferrovias S.A. network between the cities of Santa Fé do Sul and Araraquara in the state of São Paulo. The analysis of the results shows that the present railway superstructure condition is the main train average space speed limiting factor and, once this restriction is eliminated, the supression of at grade crossings and the relocation of the crossing stations produce expressive gains.

Due to the nature of tunnels, a driver in an underground mine may find themselves driving without much vision of the road up ahead. The tunnels usually allow for traffic in both directions but are often only wide enough for a single vehicle. To let vehicles pass each other meeting slots have been carved into the tunnel walls, where one can park while the other passes. Because of the limited vision, however, it is unlikely that a meeting with another vehicle will occur directly next to such a meeting slot. Instead, one of the vehicles must reverse to the closest meeting slot in order to let the other pass. This makes mine tunnels a very inhospitable driving environment, causing disruptions to traffic flow throughout the mine. Unfortunately, typical traffic management or scheduling solutions are not useful, as real-time positioning for the vehicles is often poor while network connectivity cannot be guaranteed in the mine environment. This thesis presents a solution which will avoid situations where a driver needs to back up, and instead present meeting slots in which to park ahead of time. This is done by calculating velocity probability distributions for road segments from historical data and using these to estimate arrival times to meeting slots. In addition, a more comprehensive solution is presented, taking into account the accuracy of positioning, outdated information due to poor connections and more complicated scenarios. The results show that estimating arrival times using only historical data is a very feasible technology, which can realistically be implemented today. Such an implementation could, in the author's opinion, improve driver safety and efficiency significantly, compared to a driver having no information or simply knowing rough positions of nearby vehicles. This being said, there are still steps that can be taken to improve the solution and to develop a more comprehensive system overall.

The subject of this thesis is to design an electric scooter targeted at innovative approach to the design of the technical, aesthetic , ergonomic and ecological requirements . The main objective is to devise a practical design and shape characteristic of the machine , which in itself will reflect the selected drive type . The scooter should be the ideal solution for the movement in urban centers, which will be practical with an attractive appearance of ecological vehicles . Its unusual solution to the problem of storage space in this category of motorcycle , scooter would have become a good alternative to conventional means of transport with a combustion engine

The diploma thesis deals with computational analysis of driving behavior of a vehicle. The first section summarizes and explains the basic parameters of steering geometry. Next section covers the tests which are used to study driving behavior of vehicles. The practical part consists of computational model that is able to simulate and evaluate tests of step steer input.

The main aim of this dissertation was to develop a computational tool capable of evaluating the influence of aerodynamics on the handling of a vehicle. The methodology it uses is based on the simulation of driving manoeuvres with a single-track model of a vehicle, which was composed with an emphasis on minimizing the amount of necessary input parameters. This simple model, which allows the assessment of the influence of aerodynamics on vehicle dynamic and static driveability, therefore doesn’t require large amount of input data, which makes the acquirement of relevant values easier. The computational model was validated by extensive measurements of two driving manoeuvres defined by ISO norms (step steer input and steady state cornering). As a consequence of unsatisfactory initial validation results, the differences between measurements and simulations were analysed, which led to gradual enhancements of the model with additional inputs to achieve better accuracy of simulations. The final part of the thesis deals with the comparison of influences of individual aerodynamic parameters on vehicle handling and the assessment of overall significance of aerodynamics compared to other factors which were taken into account (tires, mass properties, steering etc.). This thesis was realized in close cooperation with Škoda-Auto.

The use of global positioning systems, or GPS, as a means of logistical organization for fleet vehicles has become more widespread in recent years. The system has the ability to track vehicle location, report on diagnostic trouble codes, and keep tabs on maintenance schedules. This helps to improve the safety and productivity of the vehicles and their operators. Additionally, the increasing use of yaw and roll stability control in commercial trucks has contributed to an increased level of safety for truck drivers. However, these systems require the vehicle to begin a yaw or roll event before they assist in maintaining control. This thesis presents a new method for utilizing the GPS signal in conjunction with a new fuzzy logic-based stability index, the Total Safety Margin (TSM), to create a superior active safety system. This thesis consists of four main components: An overview of GPS technology is presented with coverage of several automotive-based applications. The proposed implementation of GPS in the new Hardware-in-the-Loop (HIL) driving simulator under development at the Virginia Tech Center for Vehicle Systems and Safety (CVeSS) is presented. The three degree-of-freedom (3DOF), linear, single track equation set used in the Matlab simulations is derived from first principles. Matlab and TruckSim 7® simulations are performed for five vehicle masses and three forward velocities in a ramp-steer maneuver. Using fuzzy logic to develop the control rules for the Total Safety Margin (TSM), TSM matrices are built for both the Matlab and TruckSim 7® results based on these testing conditions. By comparing these TSM matrices it is shown that the two simulation methods yield similar results. A discussion of the development and implementation of the aforementioned HIL driving simulator is presented, specifically the steering subsystem. Using Matlab/Simulink, dSPACE ControlDesk, and CarSim RT® software it is shown that the steering module is capable of steering the CarSim RT® simulation vehicle accurately within the physical range of the steering sensor used. / Master of Science

Cross wind analysis is one of the important safety measures for rail vehicle certification. The objective of this study is to identify which vehicle certification ground setup, true flat ground (TFG) or single track ballast and rail (STBR) represents a more realistic ground setup with atmospheric boundary layer (ABL) wind inlet and also to represent an embankment scenario. A streamlined high speed train ICE3 and a conventional Regional train are taken for the analysis to represent both categories. CFD is used as a tool for calculations. The best practice recommended by the AeroTRAIN project is used for the CFD approach. The analysis is done for various configurations including STBR, TFG, embankments, ground roughness, moving ground, non-moving ground, block profile inlet, ABL inlet, model scale and full scale setups. The Regional train shows higher roll moment coefficient about lee rail (Cmx,lee) compared to the ICE3 train, whereas the ICE3 train has a higher lift force coefficient than the Regional train. STBR setup shows a higher force and moment coefficient compared to TFG. The STBR setup represents the more realistic setup of moving rough ground with ABL wind inlet and also the realistic embankment scenario.

The goal of this thesis work is to evaluate and quantify the advantages and disadvantages of Active Rear Steering (ARS). The evaluation is carried out through Multi-Body System (MBS) simulations. An analytical model has been developed to better understand the basic dynamics of vehicles equipped with rear steering. In parallel, a high fidelity MBS model is developed in Simpack. This model includes suspension kinematics and compliance, allowing for detailed analyses of steering hardware performance. Next, different control strategies aiming at improving manoeuvrability, stability and agility are implemented in Simulink. In order to assess their effectiveness, the high fidelity model is utilised by running co-simulation with Simulink. Manoeuvrability is assessed through constant steer, constant radius and ramp steer manoeuvres. Stability is assessed through transient manoeuvres such as step steer and sine with dwell. Agility is assessed through step steer and frequency response. Ultimately, also a subjective assessment is carried out by means of Volvo Cars' dynamic driving simulator. The conclusion from the assessment is that the drivers feel the all wheel steered vehicle more stable during evasive manoeuvres. It is concluded that for manoeuvrability the minimum turning radius is reduced by 19 % at low velocity; this implies that the steering angle request is reduced at low velocity, while it is increased at high velocity. A slightly higher steering angle request at high velocity might be beneficial since the driver would be able to control the vehicle in a wider range of steering wheel angles. For agility the results are contradicting: on the one hand, according to the step steer rise time difference between lateral acceleration and yaw rate, the controlled vehicles are performing worse than the passive vehicle; on the other hand, according to the frequency response analysis, both the delays between steering input and yaw rate and between lateral acceleration and yaw rate are reduced up to respectively 75 % and 46 % for the considered frequency range. Finally, for stability, the yaw rate overshoot from a step steer can be reduced up to 65 % at high velocity and the sideslip angle can always be reduced. The vehicle equipped with ARS outperforms the passive vehicle in the sine with dwell manoeuvre. / Målet med detta examensarbete är att utvärdera och kvantifiera fördelarna och nackdelarna med Active Rear Steer (ARS) för Volvo Cars. Utvärderingen utförs genom Multi-Body System (MBS) simuleringar. En analytisk modell har utvecklats för att bättre förstå den grundläggande dynamiken i fordon utrustade med bakhjulsstyrning. Parallelt utvecklades en MBS-modell med hög precision i Simpack. Denna modell inkluderar hjulupphängningens kinematik och eftergivlighet, vilket möjliggör detaljerade analyser av styrhårdvarans prestanda. Därefter implementeras olika kontrollstrategier som syftar till att förbättra manövrerbarhet, stabilitet och agilitet i Simulink. För att bedöma deras effektivitet används MBS-modellen för att köra co-simulering med Simulink.Manövrerbarhet bedöms genom konstant styrning, konstant radie och rampstyrning. Stabilitet bedöms genom transienta manövrar som stegstyrning och sinus med fördröjning. Agilitet bedöms genom stegstyrning och frekvensrespons. Slutligen görs också en subjektiv bedömning med hjälp av Volvo Cars dynamiska körsimulator. Slutsatsen från bedömningen är att förarna anser att fordonet upplevs vara mycket stabilare vid undanmanövrar. Vidare är slutsatsen att för manövrerbarhet minskar den minsta svängradien med 19 % vid mycket låg hastighet; detta innebär att styrvinkel reduceras vid låg hastighet, medan den ökar vid hög hastighet. En något högre styrvinkeln kan vara fördelaktig eftersom föraren skulle kunna styra fordonet i ett större rattvinkelområde. För agilitet är resultaten motsägelsefulla: å ena sidan, enligt stegstyrningstidsskillnaden mellan lateral acceleration och girhastighet, fungerar de aktiva fordonen sämre än det passiva fordonet; å andra sidan, enligt frekvensresponsanalysen, reduceras både fördröjningarna mellan girhastighet och styrvinkel och mellan lateral acceleration och girhastighet upp till ungefär 30 %. Slutligen, för stabilitet, kan girhastighetens översläng från en stegstyrning minskas upp till 65 % vid hög hastighet och avdriftsvinkeln kan alltid minskas. Fordonet som är utrustat med ARS överträffar det passiva fordonet i manövern sinus med fördröjning.

This thesis shows the advantages of simple models for analysis of railway operation. It presents two tools for infrastructure and timetable planning. It shows how the infrastructure can be analysed through fictive line designs, how the timetable can be treated as a variable and how delays can be used as performance measures. The thesis also gives examples of analyses of complex traffic situations through simulation experiments. Infrastructure configuration, timetable design and delays play important roles in the competitiveness of railway transportation. This is especially true on single-track lines where the run times and other timetable related parameters are severely restricted by crossings (train meetings). The first half of this thesis focuses on the crossing time, i.e. the time loss that occurs in crossing situations. A simplified analytical model, SAMFOST, has been developed to calculate the crossing time as a function of infrastructure configuration, vehicle properties, timetable and delays for two crossing trains. Three measures of timetable flexibility are proposed and they can be used to evaluate how infrastructure configuration, vehicle properties, punctuality etc affect possibilities to alter the timetable. Double-track lines operated with mixed traffic show properties similar to those of single-tracks. In this case overtakings imply scheduled delays as well as risk of delay propagation. Two different methods are applied for analysis of double-tracks: a combinatorial, mathematical model (TVEM) and simulation experiments. TVEM, Timetable Variant Evaluation Model, is a generic model that systematically generates and evaluates timetable variants. This method is especially useful for mixed traffic operation where the impact of the timetable is considerable. TVEM may also be used for evaluation of different infrastructure designs. Analyses performed in TVEM show that the impact on capacity from the infrastructure increases with speed differences and frequency of service for the passenger trains, whereas the impact of the timetable is strongest when the speed differences are low and/or the frequency of passenger services is low. Simulation experiments were performed to take delays and perturbations into account. A simulation model was set up in the micro simulation tool RailSys and calibrated against real operational data. The calibrated model was used for multi-factor analysis through experiments where infrastructure, timetable and perturbation factors were varied according to an experimental design and evaluated through response surface methods. The additional delay was used as response variable. Timetable factors, such as frequency of high-speed services and freight train speed, turned out to be of great importance for the additional delay, whereas some of the perturbation factors, i.e. entry delays, only showed a minor impact. The infrastructure factor, distance between overtaking stations, showed complex relationships with several interactions, principally with timetable factors. / QC20100622 / Framtida infrastruktur och kvalitet i tågföring

Additive manufacturing (AM) is the name given to the technology of building 3D parts by adding layer-by-layer of materials, including metals, plastics, concrete, etc. Of the different types of AM techniques, electron beam melting (EBM), as a powder bed fusion technology, has been used in this study. EBM is used to build parts by melting metallic powders by using a highly intense electron beam as the energy source. Compared to a conventional process, EBM offers enhanced efficiency for the production of customized and specific parts in aerospace, space, and medical fields. In addition, the EBM process is used to produce complex parts for which other technologies would be either expensive or difficult to apply. This thesis has been divided into three sections, starting from a wider window and proceeding to a smaller one. The first section reveals how the position-related parameters (distance between samples, height from build plate, and sample location on build plate) can affect the microstructural characteristics. It has been found that the gap between the samples and the height from the build plate can have significant effects on the defect content and niobium-rich phase fraction. In the second section, through a deeper investigation, the behavior of Alloy 718 during the EBM process as a function of different geometry-related parameters is examined by building single tracks adjacent to each other (track-by-track) andsingle-wall samples (single tracks on top of each other). In this section, the main focus is to understand the effect of successive thermal cycling on microstructural evolution. In the final section, the correlations between the main machine-related parameters (scanning speed, beam current, and focus offset) and the geometrical (melt pool width, track height, re-melted depth, and contact angle) and microstructural (grain structure, niobium-rich phase fraction, and primary dendrite arm spacing) characteristics of a single track of Alloy 718 have been investigated. It has been found that the most influential machine-related parameters are scanning speed and beam current, which have significant effects on the geometry and the microstructure of the single-melted tracks.