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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Epicyclic Gear Train Solution Techniques with Application to Tandem Bicycling

Corey, Christopher A. 18 December 2003 (has links)
This thesis presents a unification of kinematic and force-based methods for the design and analysis of planetary gear trains along with a discussion of potential applications in tandem biking. Specifically, this thesis will provide a simple solution technique for the general case of a two-degree of freedom (2DOF) planetary gear train along with new graphical design aids. It will also address the use of epicyclic gear trains as a power coupling in a tandem bike. In the current literature, planetary gear trains are given a clear treatment with regard to the pure kinematics of the system, but little or no literature exists that includes the torques present in the system. By treating both the kinematics and torque balance of the most general case, this thesis attempts to fill a void in the current literature. After developing the solution to the general two-degree of freedom case using the Willis formula, a force analysis will be performed using the conservation of energy principle assuming zero losses. Once the total solution is known, nomographs will be presented as a simple design tool. These graphical aids enable the designer to simultaneously approximate both speeds and torques for the mechanism. After fully developing a satisfactory solution technique and design tools, these will be applied to the problem of coupling the power provided by the riders of a tandem bicycle. / Master of Science
32

Power Flow Analysis on the Dual Input Transmission Mechanisms of Wind Turbine Systems

Hsiao, Hsien-yu 21 July 2011 (has links)
Two parallel planetary gear trains design are proposed to construct a dual input transmission mechanism system used in small power wind turbine systems. The time varied input wind powers are applied in the system with specified speed and torque. The Dynamic power flow variation in gear pairs are modeled and simulated in this work. Results indicate the proposed planetary gear train system is feasible in wind turbine system. The effect of gear train parameters on the operation safety and life will also be studied. The dynamic torque equilibrium equations between meshed gear pairs are employed to model the dynamic torque flow in this proposed dual input gear system. The nonlinear behavior of a synchronous generator has also included in the modeling. The dynamic responses of the dual input transmission mechanism system are simulated by using the 4th order Runge-Kutta method. The effect of system parameters used in this wind turbine system, i.e. the wind speed, the magnetic flux synchronous generator, the inertia flywheels, on the output electrical power variation have investigated in this study. The strength analyses of gear pairs with the bending fatigue and surface durability consideration have also studied in this work.
33

Aspects of automatic train control

Milroy, Ian P. January 1980 (has links)
This thesis describes research and development. work carried out by the author into the control of traction and braking systems on rail vehicles. After a review of recent developments, the problem of. driving a train under minimum-energy control subject·to timetable and operational constraints is discussed. This is partitioned into two sections. Firstly, target time and velocities for key pOints on the journey are computed; these are communicated to or stored on the train, together with route and vehicle data. Secondly, an on-board digital system drives the train to each target according to control algorithms which incorporate a predictorcorrector module, whose function is to determine which of two criteria of performance is to be used (minimum-energy when running early or on-time, minimum-time when running late). Most of the thesis is devoted to the analysis and design of the train-borne control system. The general form of the optimal control (of tractive or braking effort) is determined by the application of Pontryagin's Maximum Principle over each section of the journey. However, the moments of transition between the various modes of control are calculated by a method which involves a lookahead model in the predictor module, rather than by iterative solution of the state and co-state equations . An important aspect of the design is the dynamic response of the braking SUb-system, which may include a substantial pneumatic transport lag within the control loop. S-plane and z-plane design procedures for the required discrete control algorithms to.achieve a specified transient response are derived. The thesis concludes with a chapter on the instrumentation required for the train-borne control system.
34

Vyšetření dynamického namáhání ventilového rozvodu OHV / Calculation of OHV-Valve Gear Dynamic Stress

Opluštil, Tomáš January 2008 (has links)
This diploma thesis deals with investigation of dynamic straining valve OHV for four-valve head diesel engine Zetor 1505 – 90 kW. The calculation is performed analytically in mathematic software MathCad and MBS software ADAMS/Engine 2005. Also in this diploma thesis is from results obtained from MBS system perfomed stressed analysis valve_rocker arm gear divorce method final elements (MKP) in program ANSYS 10.
35

”VART ÄR VI PÅ VÄG?” / WHERE ARE WE GOING?

Grundmark, Anna January 2019 (has links)
In the middle of the nineteenth century, the train came to Sweden. It has been just over 150 years and a lot has happened. With the train and its station came more then just a means of transportation, it turned Sweden from a developing country into one of the most modern. In the small Swedish cities and on the countryside, the stations became a central node, a meeting point and a place to gather. The train passed through previously isolated areas where the stations became not only just that but also a window towards the rest of the world. This project is a study of the Swedish train station and a humble proposal on how to treat them, what to do with them and when to do it (now).
36

Train-Bridge Interaction on Freight Railway Lines

Martino, Davide January 2011 (has links)
This study investigates the dynamic response of a railway bridge under train passage. Three load models designed around the Swedish Steel Arrow freight train are tested and compared. A series of Concentrated Forces, a succession of single degree of freedom Sprung-Masses, and a sequence of complex multi-degree of freedom Train Wagons. The increase in accuracy of the representation corresponds to taking into account the inertial properties of the wagons. The track-bed layer is substitute by a sequence of regularly spaced couple of springs and dampers at the sleeper distance. Under the assumption of this work, a portion of the ballast vibrates with the sleeper during train passage. Both bridge and rail are modelled under Bernoulli-Euler beam theory. The dynamic behavior of the bridge is investigated in presence or absence of vertical track irregularities. The main conclusions of the report can be summarized as:   • the dynamic amplification attains its maximum value, for every train model, at the critical train speeds of 120 km/h. Proper resonance has also been detected at the speed of 60 km/h in all the simulations;   • the Concentrated Forces model provided an upper boundary of the acceleration response of the bridge while the Sprung-Mass systems a lower boundary. The response of the two models is in very good agreement at non resonance speeds. The simulation with Train Wagons loading does not fit completely this trend, it adds two peaks on the diagram; Besides that, the bridge response lies between the two limits;   • the presence of track irregularities determines a variation of the bridge dynamics only if combined with Train Wagon load model. The Concentrated Force pattern couldn’t detect the modification of the profile while the Sprung-Masses case provided a diagram of maximum acceleration similar to the one over flat rail simply shifted upwards;   • the position of the track irregularities along the bridge influence its dynamics.
37

An ILP-model for the Train platforming problem

Calderon, Simon January 2023 (has links)
The goal of this thesis is to create an optimization model to optimize the routing of trains within railway stations. This problem is known as the train platforming problem, and the model we present is an integer programming model. By this model we aim to optimize factors such as walking distance, switch usage or platform usage. We validate the model by implementing the model for Linköping station, which is a typical mid size station in the Swedish railway network. This implementation is done for different time horizons, ranging from 2 hours to one day, which corresponds to train sets ranging from 27 to 265 trains. In the conclusion we see that the model is efficient for optimizing the train platforming problem for the implemented station and timetables, and that the model has a possibility to optimize the four objectives tested. Furthermore we see that optimizing certain objectives gives solutions that are also good with regards to other objective functions. / Målet med den här uppsatsen är att skapa en optimeringsmodell för att optimera valet av vägar för tåg genom tågstationer. Modellen vi presenterar är en heltalsmodell, där syftet är att minimera bland annat gångavstånd, användningen av tågväxlar eller användningen av perronger. För att testa modellen presenterar vi en implementation av modellen för stationen i Linköping, vilken är en typisk mellanstor station i det svenska tågnätet. Impplementeringen är gjord för olika tidslängder, från 2 timmar till ett dygn vilket motsvarar dataset från 27 till 265 tåg. Vi drar slutsatsen att modellen på ett effektivt sätt kan lösa valet av tågvägar genom stationen, för de fyra tidtabeller och den station vi har implementerat. Vidare ser vi att modellen har potential att optimera de fyra målfunktioner vi testat och att optimering av några av målfunktionerna ger lösningar som är bra även med hänsyn till de andra målfunktionerna.
38

A Multibody Dynamics Approach to the Modeling of Friction Wedge Elements for Frieght Train Suspensions

Steets, Jennifer Maria 07 June 2007 (has links)
This thesis presents a theoretical application of multibody dynamics with unilateral contact to model the interaction of the damping element in a freight train suspension, the friction wedge, with the bolster and the side frame. The objective of the proposed approach is to produce a stand-alone model that can better characterize the interaction between the bolster, the friction wedge, and the side frame subsystems. The new model allows the wedge four degrees of freedom: vertical displacement, longitudinal (between the bolster and the side frame) displacement, pitch (rotation about the lateral axis), and yaw (rotation about the vertical axis). The new model also allows for toe variation. The stand-alone model shows the capability of capturing dynamics of the wedge which were not possible to simulate using previous models. The inclusion of unilateral contact conditions is integral in quantifying the behavior during lift-off and the stick-slip phenomena. The resulting friction wedge model is a 3D, dynamic, stand-alone model of a bolster-friction wedge-side frame assembly. The new stand-alone model was validated through simulation using simple inputs. The dedicated train modeling software NUCARS® has been used to run simulations with similar inputs and to compare — when possible — the results with those obtained from the new stand-alone MATLAB friction wedge model. The stand-alone model shows improvement in capturing the transient dynamics of the wedge better. Also, it can predict not only normal forces going into the side frame and bolster, but also the associated moments. Significant simulation results are presented and the main differences between the current NUCARS® models and the new stand-alone MATLAB models are highlighted. / Master of Science
39

Advanced Multibody Dynamics Modeling of the Freight Train Truck System

Ballew, Brent Steven 05 June 2008 (has links)
Previous work in the Railway Technology Laboratory at Virginia Tech focused on better capturing the dynamics of the friction wedge, modeled as a 3D rigid body. The current study extends that work to a half-truck model treated as an application of multibody dynamics with unilateral contact to model the friction wedge interactions with the bolster and the sideframe. The half-truck model created in MATLAB is a 3D, dynamic, multibody dynamics model comprised of four rigid bodies: a bolster, two friction wedges, and a sideframe assembly. The model allows each wedge four degrees of freedom: vertical displacement, longitudinal displacement (between the bolster and sideframe), pitch (rotation around the lateral axis), and yaw (rotation around the vertical axis). The bolster and the sideframe have only the vertical degree of freedom. The geometry of these bodies can be adjusted for various simulation scenarios. The bolster can be initialized with a pre-defined yaw (rotation around the vertical axis) and the sideframe may be initialized with a pre-defined pitch/toe (rotation around the lateral axis). The multibody dynamics half-truck model simulation results have been compared with results from NUCARS®, an industry standard train modeling software, for similar inputs. The multibody dynamics models have also been extended to a variably damped full-truck model and a variably damped half-truck warping model. These models were reformulated to react dynamically to simulated truck warp inputs. The ability to better characterize truck warping properties can prevent train roll over and derailments from truck hunting. In a quarter-truck variably damped configuration the effects of a curved wedge surface has also been explored. Actual friction wedges have surfaces which are slightly curved, this iteration in the multibody dynamics friction wedge modeling attempts to draw one step closer to actual friction wedge geometry. This model lays the ground work for a contact dependant wedge wearing model based on material properties and tribology. / Master of Science
40

Influência do uso de trens de caixa móvel na implantação e operação de novas ferrovias. / Influence of the use of tilting trains on the implementation and operation of new railways.

Lucas, Felipe Rabay 16 March 2015 (has links)
O presente trabalho tem por objetivo primário abordar os atuais conhecimentos sobre o transporte ferroviário interurbano e regional de passageiros, com foco na tecnologia dos trens de caixa móvel, também conhecidos como trens pendulares. Como objetivo secundário busca-se analisar a influência dos trens de caixa móvel ou pendulares na implantação e operação de novas ferrovias, com ênfase na adequação em fase de projeto, mostrando-se o potencial dessa tecnologia para o aumento da velocidade média e a redução dos tempos de viagem. São tratados os tópicos relevantes para o transporte ferroviário de passageiros, como o conforto do usuário, as especificações técnicas do material rodante e referências dos custos de implantação e operação envolvidos, mostrando-se também dentro de cada aspecto as diferenças dos trens pendulares em relação aos trens convencionais. Três estudos de caso elaborados terão como objetivo explicitar as interveniências da operação dos trens pendulares com o projeto ferroviário, em especial com o projeto geométrico, e através de simulações de marcha e comparações, mostrar de maneira prática o potencial do uso dos trens pendulares. Através do embasamento teórico e dos estudos de caso, é feita uma análise crítica de modo a possibilitar tanto um entendimento do transporte ferroviário de passageiros, quanto do material rodante de caixa móvel e suas possibilidades. Os resultados dos estudos de caso e a análise crítica mostram uma redução significativa dos tempos de viagem, entre 8,1 e 20,0%, mediante a operação de trens pendulares em substituição ao material rodante convencional. / As a primary objective, the present work aims to summarize the current knowledge on intercity and regional passenger railway transportation, focusing on tilting train technology, also known as car body tilt. As a secondary objective, the present work seeks to analyze the influence of tilting train technology on the design, implementation and operation of new railway corridors, with emphasis on design phase, showing the potential of this technology to increase speeds and reduce travel times. Railway passenger transportation issues, such as passenger comfort, rolling stock technical specifications and implementation and operational costs are addressed. Additionally, different aspects between conventional and tilting trains are also discussed. Three case studies help clarify the correlation between tilting train operation and railway design, especially the geometric design; further, with the help of speed simulations and comparisons, the potential use of tilting train operations are demonstrated. With the theoretical basis and the case studies, a critical analysis is made, allowing as a better understanding of railway passenger transportation with regards to the use of tilting rolling stock and its possibilities. The results of the case studies and the critical analysis present a considerable reduction in travel times, between 8,1 and 20,0%, with the operation of tilting trains in the place of the conventional rolling stock.

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