Introduction of variability into pantograph–catenary dynamic simulations

Currently, pantograph-catenary dynamic simulations are mainly based on deterministic approaches. However, the contact force between catenary and pantograph depends on many key parameters that are not always quantified precisely and can vary in time and space. To get a better chance of addressing extreme or combined critical conditions, methodologies to consider variability are thus necessary. Aerodynamic forces and geometrical irregularities of catenaries are thought to be significant sources of variability in measurement and this paper proposes methods to take them into account. Results are compared with measurements to correlate the effect of the considered parameters with experimentally observed variability. Finally, a virtual certification example is shown, with a study of the influence of speed on the impact of variability.SNC

Efficient simulation of the pantograph-catenary dynamic interaction. Catenary optimisation and installation error analysis

Tesis por compendioEl modelado y la simulación de la interacción dinámica entre el pantógrafo y la catenaria se ha convertido en una herramienta imprescindible para agilizar el proceso de diseño de catenarias ferroviarias ya que, entre otras ventajas, es posible reducir el número necesario de los tan costosos ensayos experimentales en vía. Para la realización de dichas simulaciones numéricas, la catenaria se modela mediante el método de los Elementos Finitos, mientras que el modelo del pantógrafo es de parámetros concentrados. La interacción entre ambos sistemas se trata con un método de penalti. Tras resolver el problema no lineal de configuración inicial, la ecuación del movimiento se linealiza, y se resuelve con la técnica HHT. Sin embargo, el aflojamiento de las péndolas y los despegues del pantógrafo son dos fuertes no linealidades que deben ser consideradas en la resolución del problema dinámico, aunque aumenten notablemente el coste computacional de cada simulación. Los objetivos principales de esta Tesis son encontrar catenarias óptimas en términos de calidad de captación de corriente y analizar los efectos de los errores de montaje de la catenaria. Para alcanzarlos, es necesario realizar un número elevado de simulaciones de la interacción dinámica entre pantógrafo y catenaria, cuyo coste computacional puede llegar a ser prohibitivo. Para reducir el coste computacional, la primera propuesta se basa en el cálculo de una solución paramétrica de la interacción dinámica entre pantógrafo y catenaria, para cualquier valor de las variables de diseño, por medio de la técnica Proper Generalised Decomposition (PGD). Si las longitudes de las péndolas son consideradas como variables de diseño, la aplicación de este método resulta exitosa en el caso del problema de equilibrio estático, pero no en el caso del dinámico, donde se considera que las péndolas no transmiten fuerzas a compresión. La solución del problema resulta muy sensible ante pequeños cambios de las variables y por tanto, se requiere de un elevado número de modos PGD para tener una solución paramétrica de suficiente precisión. La segunda propuesta consiste en el desarrollo de una estrategia para resolver el problema de interacción dinámica con la que se reduzca considerablemente el tiempo de cálculo. El algoritmo propuesto se divide en dos fases y se basa en pasar los términos no lineales a la parte derecha de la ecuación de la dinámica del sistema. Tras el cálculo y almacenamiento de la respuesta ante fuerzas unitarias, en la segunda etapa del método, el tratamiento de las no linealidades se condensa en un sistema de ecuaciones pequeño cuyas incógnitas son las fuerzas relacionadas con dichas no linealidades, en vez de los desplazamientos nodales globales. Con este algoritmo eficiente, es posible llevar a cabo la optimización de la geometría de catenarias ferroviarias. En concreto, la altura del cable de contacto y la separación entre péndolas son los parámetros de diseño a optimizar para obtener así una captación de corriente óptima. El problema de optimización se resuelve mediante un Algoritmo Genético clásico, y se aplica a diferentes tipos de catenarias. Los resultados obtenidos indican que un diseño óptimo de la geometría puede mejorar notablemente la captación de corriente de las catenarias actuales. Finalmente, se estudia la influencia que tienen los errores de montaje de la catenaria en el comportamiento dinámico del sistema. Con un planteamiento estocástico, se considera variabilidad en la longitud de las péndolas, en la separación entre ellas y en la altura de los soportes. Mediante la aplicación un método clásico de Montecarlo, se propaga la incertidumbre a las magnitudes de interés y se obtiene su función de densidad de probabilidad. Los resultados muestran que los errores cometidos en la colocación de las péndolas apenas influyen en la respuesta del sistema, mientras que errores en lModelling and simulation of the dynamic interaction between pantograph and catenary has become a powerful tool to expedite the catenary design process since, among other advantages, it helps in reducing the number of the costly experimental in-line tests. In order to tackle these numerical simulations, in this Thesis the catenary system is modelled by the Finite Element technique, while a simple lumped-mass model is used for the pantograph. The interaction between the two systems is accomplished with a penalty formulation. After solving the initial nonlinear configuration problem, the equation of motion is linearised with respect to the static equilibrium position and it is then solved by applying the Hilber-Hughes-Taylor (HHT) time integration method. However, dropper slackening and pantograph contact losses are two sources of nonlinearities which must be considered in the solution procedure at the expense of an increase in the computational cost. The main objectives of this Thesis are both to find optimal catenaries in terms of current collection quality and to analyse the effect of installation errors in the dynamic behaviour of the system. To achieve these goals, it is mandatory to perform a large number of pantograph-catenary dynamic simulations for which the computational cost can become prohibitive. In order to reduce this computational effort, the first proposal made in this Thesis is to precompute a parametric solution of the pantograph-catenary dynamic interaction for all values of the design variables, by means of the Proper Generalised Decomposition (PGD) technique. If dropper lengths are considered as design variables, this parametric approach is successful when applied to the static equilibrium problem. Nevertheless, in the dynamic case, when dropper slackening is considered, the solution exhibits a great sensitivity to small changes in the parameters and therefore, a huge number of PGD modes are required to obtain the parametric solution with enough accuracy. The impossibility of having a parametric solution leads the author to propose a fast strategy to simulate the dynamic interaction problem, providing remarkable saves in computational cost. The method is divided into two stages which are based on moving the nonlinear terms to the right hand side of the dynamic equation. In the first stage, the response of the system under unitary forces is precomputed and stored. Then, in the second stage of the method, the treatment of the nonlinearities is condensed into a small system of equations, whose unknowns are now the forces associated with the nonlinearities instead of the nodal displacements of the whole system. With this proposed algorithm, it is possible to carry out efficient optimisations of the catenary geometry. Specifically, contact wire height and dropper spacing are considered as design variables in order to obtain the most uniform interaction force that leads to the optimal current collection. The optimisation problem is solved by means of a classic Genetic Algorithm, applied to both simple and stitched catenaries. The results obtained show that an optimal catenary design can remarkably improve the current collection quality of the actual catenaries. Finally, the influence of the installation errors on the dynamic behaviour of the system is analysed under a stochastic approach in which variability in dropper length, dropper spacing and support height are involved in the simulations. The use of a Monte Carlo method allows the propagation of the uncertainty to the magnitudes of interest of the dynamic solution and therefore, to obtain their probability density function. The results of Monte Carlo simulations demonstrate that dropper spacing errors are slightly influential, whilst dropper length and supsupport height installation errors have a strong influence on the dynamic behaviour of the system.El modelatge i la simulació de la interacció dinàmica entre el pantògraf i la catenària ha esdevingut en una ferramenta imprescindible per a agilitzar el procés de disseny de catenàries ferroviàries degut, entre altres coses, a la possibilitat de reduir el nombre dels tan costosos assajos experimentals en via. Per a la realització d'aquestes simulacions numèriques, la catenària es modela mitjançant el mètode dels Elements Finits, mentre que el model de pantògraf és de paràmetres concentrats. La interacció entre ambdós sistemes es tracta amb un mètode de penalti. Després de resoldre el problema no-lineal de configuració inicial, l'equació del moviment es linealitza i es resol amb la tècnica HHT. Tanmateix, l'afluixament de les pèndoles a compressió i la pèrdua de contacte del pantògraf són dues fortes no-linealitats que han de ser considerades en la resolució del problema dinàmic, malgrat l'augment que produeixen del cost computacional de cada simulació. Els objectius principals d'aquesta Tesi són trobar catenàries òptimes en termes de qualitat de captació de corrent i analitzar els efectes dels errors de muntatge de la catenària. Per a assolir-los és necessari realitzar un nombre elevat de simulacions de la interacció dinàmica entre pantògraf i catenària, el que pot comportar un cost computacional prohibitiu. Per tal de reduir el cost computacional, la primera proposta consisteix a calcular una solució paramètrica del problema d'interacció dinàmica entre pantògraf i catenària, per a qualsevol valor de les variables de disseny, mitjançant la tècnica Proper Generalised Decomposition (PGD). Si les longituds de les pèndoles es consideren com a variables de disseny, l'aplicació d'aquest mètode és exitosa en el cas del problema d'equilibri estàtic, però no en el cas del dinàmic, on es considera que les pèndoles no poden transmetre força a compressió. La solució del problema és molt sensible a xicotets canvis de les variables i per tant, es necessita un elevat nombre de modes PGD per a obtenir una solució paramètrica amb suficient precisió. La segona proposa consisteix en el desenvolupament d'una estratègia per a resoldre el problema d'interacció dinàmica que reduïsca considerablement el temps de simulació. L'algoritme proposat es divideix en dues fases i es basa a moure els termes no lineals a la part dreta de l'equació de la dinàmica del sistema. Després de calcular i s'emmagatzemar la resposta del sistema a forces unitàries, en la segona etapa del mètode, el tractament de les no linealitats es condensa en un xicotet sistema d'equacions les incògnites del qual passen a ser forces en compte de desplaçaments. Amb aquest algoritme eficient, s'ha pogut realitzar l'optimització de la geometria de catenàries ferroviàries. En concret, l'altura del cable de contacte i la separació entre pèndoles es consideren com a paràmetres a optimitzar per a obtenir una òptima captació de corrent. L'optimització es porta a terme mitjançant un Algoritme Genètic clàssic, i s'aplica a diferents tipus de catenàries. Els resultats obtinguts indiquen que un disseny òptim de la geometria pot millorar notablement la captació de corrent de les actuals catenàries. Finalment s'estudia la influència que tenen les errades de muntatge de la catenària en el comportament dinàmic del sistema. Aquest plantejament estocàstic considera variabilitat en la longitud de les pèndoles, la separació entre aquestes i l'altura dels suports. Per mitjà d'un mètode clàssic de Montecarlo, es propaga la incertesa a les magnituds d'interés i s'obté la seua funció de densitat de probabilitat. Els resultats mostren que hi ha molt poca influència per part de les errades comeses en la col·locació de les pèndoles, mentre que errades en la longitud de les pèndoles i en l'altura dels suports sí que influeixen considerablement en el comportament dinàmic del sistema.Gregori Verdú, S. (2018). Efficient simulation of the pantograph-catenary dynamic interaction. Catenary optimisation and installation error analysis [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/104507TESISCompendi

A cloudification methodology for high performance simulations

Mención Internacional en el título de doctorMany scientific areas make extensive use of computer simulations to study complex real-world processes. These computations are typically very resource-intensive and present scalability issues as experiments get larger, even in dedicated supercomputers since they are limited by their own hardware resources. Cloud computing raises as an option to move forward into the ideal unlimited scalability by providing virtually infinite resources, yet applications must be adapted to this paradigm. The major goal of this thesis is to analyze the suitability of performing simulations in clouds by performing a paradigm shift, from classic parallel approaches to data-centric models, in those applications where that is possible. The aim is to maintain the scalability achieved in traditional HPC infrastructures, while taking advantage of Cloud Computing paradigm features. The thesis also explores the characteristics that make simulators suitable or unsuitable to be deployed on HPC or Cloud infrastructures, defining a generic architecture and extracting common elements present among the majority of simulators. As result, we propose a generalist cloudification methodology based on the MapReduce paradigm to migrate high performance simulations into the cloud to provide greater scalability. We analysed its viability by applying it to a real engineering simulator and running the resulting implementation on HPC and cloud environments. Our evaluations will aim to show that the cloudified application is highly scalable and there is still a large margin to improve the theoretical model and its implementations, and also to extend it to a wider range of simulations.Muchas áreas de investigación hacen uso extensivo de simulaciones informáticas para estudiar procesos complejos del mundo real. Estas simulaciones suelen hacer uso intensivo de recursos, y presentan problemas de escalabilidad conforme los experimentos aumentan en tamaño incluso en clústeres, ya que estos están limitados por sus propios recursos hardware. Cloud Computing (computación en la nube) surge como alternativa para avanzar hacia el ideal de escalabilidad ilimitada mediante el aprovisionamiento de infinitos recursos (de forma virtual). No obstante, las aplicaciones deben ser adaptadas a este nuevo paradigma. La principal meta de esta tesis es analizar la idoneidad de realizar simulaciones en la nube mediante un cambio de paradigma, de las clásicas aproximaciones paralelas a nuevos modelos centrados en los datos, en aquellas aplicaciones donde esto sea posible. El objetivo es mantener la escalabilidad alcanzada en las tradicionales infraestructuras HPC, mientras se explotan las ventajas del paradigma de computación en la nube. La tesis explora las características que hacen a los simuladores ser o no adecuados para ser desplegados en infraestructuras clúster o en la nube, definiendo una arquitectura genérica y extrayendo elementos comunes presentes en la mayoría de los simuladores. Como resultado, proponemos una metodología genérica de cloudificación, basada en el paradigma MapReduce, para migrar simulaciones de alto rendimiento a la nube con el fin de proveer mayor escalabilidad. Analizamos su viabilidad aplicándola a un simulador real de ingeniería, y ejecutando la implementación resultante en entornos clúster y en la nube. Nuestras evaluaciones pretenden mostrar que la aplicación cloudificada es altamente escalable, y que existe un amplio margen para mejorar el modelo teórico y sus implementaciones, y para extenderlo a un rango más amplio de simulaciones.- Administrador de Infraestructuras Ferroviarias (ADIF), Estudio y realización de programas de cálculo de pórticos rígidos de catenaria (CALPOR) y de sistema de simulación de montaje de agujas aéreas de línea aérea de contacto (SIA), JM/RS 3.6/4100.0685-9/00100 – Administrador de Infraestructuras Ferroviarias (ADIF), Proyecto para la Investigación sobre la aplicación de las TIC a la innovación de las diferentes infraestructuras correspondientes a las instalaciones de electrificación y suministro de energía (SIRTE), JM/RS 3.9/1500.0009/0-00000 – Spanish Ministry of Education, TIN2010-16497, Scalable Input/Output techniques for high-performance distributed and parallel computing environments – Spanish Ministry of Economics and Competitiveness, TIN2013-41350-P, Técnicas de gestión escalable de datos para high-end computing systems – European Union, COST Action IC1305, ”Network for Sustainable Ultrascale Computing Platforms” (NESUS) – European Union, COST Action IC0805, ”Open European Network for High Performance Computing on Complex Environments” – Spanish Ministry of Economics and Competitiveness, TIN2011-15734-E, Red de Computación de Altas Prestaciones sobre Arquitecturas Paralelas Heterogéneas (CAPAP-H)Programa Oficial de Doctorado en Ciencia y Tecnología InformáticaPresidente: Domenica Talia.- Presidente: José Daniel García Sánchez.- Secretario: José Manuel Moya Fernánde

Simulación del movimiento de trenes para minimizar el consumo enérgetico y optimización para plataformas multicore

Los avances en computación de los últimos 25 años han promovido la simulación del movimiento y consumo de trenes en circulaciones. El presente proyecto contempla la creación de un algoritmo que simula el movimiento de un tren bajo una infraestructura ferroviaria real. La ejecución de un algoritmo de este estilo supone una gran carga computacional que plantea la necesidad de usar computación en paralelo. En este documento se describen los aspectos que han envuelto la creación del proyecto.Ingeniería Informátic

Time Localization of Abrupt Changes in Cutting Process using Hilbert Huang Transform

Cutting process is extremely dynamical process influenced by different phenomena such as chip formation, dynamical responses and condition of machining system elements. Different phenomena in cutting zone have signatures in different frequency bands in signal acquired during process monitoring. The time localization of signal’s frequency content is very important. An emerging technique for simultaneous analysis of the signal in time and frequency domain that can be used for time localization of frequency is Hilbert Huang Transform (HHT). It is based on empirical mode decomposition (EMD) of the signal into intrinsic mode functions (IMFs) as simple oscillatory modes. IMFs obtained using EMD can be processed using Hilbert Transform and instantaneous frequency of the signal can be computed. This paper gives a methodology for time localization of cutting process stop during intermittent turning. Cutting process stop leads to abrupt changes in acquired signal correlated to certain frequency band. The frequency band related to abrupt changes is localized in time using HHT. The potentials and limitations of HHT application in machining process monitoring are shown

14th Conference on Dynamical Systems Theory and Applications DSTA 2017 ABSTRACTS

From Preface: This is the fourteen time when the conference “Dynamical Systems – Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and the Ministry of Science and Higher Education. It is a great pleasure that our invitation has been accepted by so many people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to participate in the conference for the first time. With proud and satisfaction we welcome nearly 250 persons from 38 countries all over the world. They decided to share the results of their research and many years experiences in the discipline of dynamical systems by submitting many very interesting papers. This booklet contains a collection of 375 abstracts, which have gained the acceptance of referees and have been qualified for publication in the conference proceedings [...]

Assessing the suitability of ship design for human factors issues associated with evacuation and normal operations

Evaluating ship layout for human factors (HF) issues using simulation software such as maritimeEXODUS can be a long and complex process. The analysis requires the identification of relevant evaluation scenarios; encompassing evacuation and normal operations; the development of appropriate measures which can be used to gauge the performance of crew and vessel and finally; the interpretation of considerable simulation data. In this paper we present a systematic and transparent methodology for assessing the HF performance of ship design which is both discriminating and diagnostic. The methodology is demonstrated using two variants of a hypothetical naval ship

Reframing Urban Design to sequence developing world cities: designing for patterns in Yeoville/Bellevue, Johannesburg

This thesis is being submitted for the Degree of Masters In Urban Design at the University of the Witwatersrand, Johannesburg.Current understandings of Urban Design point towards the fact that it is the art and science of city making. Like other aspects of Architecture, it begins with a site analysis, followed by the formulation of a vision for the built environment and thereafter a process of transforming the vision into reality (Carmona et.al, 2003). Thus, Urban Design is perceived as a discipline that gives rise to the form and defi nition of the full spectrum of forces including social, economic, cultural, ecological, political and aesthetic dynamics (Dixon, 2005). The role of the Urban Designer can therefore be understood as central to a number of other stakeholders such as Traffi c Engineers dealing with vehicular movement, Civil Engineers concerned with structural design, Architects designing built form, Landscape Architects designing open space, Urban Planners formulating policy and the Property Developers involved in aspects of land investment. However, as urban populations grow, become more diverse and fragmented, the function of Urban Design and the role of the Urban Designer becomes questionable (Madanipour, 1996). The past tradition of thought in Urban Design (visual artistic approach) incorporated a fi rm belief in the physical aspects of city making relying on built form as a primary informant. This tradition has, however, been replaced by a more recent tradition (social usage approach) which incorporates a fi rm belief in interpreting phenomena occurring in public space. This served as a response married to the phenomenon of increased population density and rapid urbanisation persistent in the developing city context due to global migration patterns (Watson, 2009). Consequently, in its plight to reframe Urban Design to sequence developing cities, this thesis conducts a comparative analysis between developed and developing world cities regarding national migratory, population density and urbanisation trends and the effects that it poses on regions, cities and localities. In so doing, it progresses to a realisation that increased living densities in turn spills over into the public realm and onto the street edge for retail and social service access purposes. Thus, a greater mix of uses in the built environment is forged. The increased density of people on sidewalks in essence stimulates transport movement as a collector service which structures street connectivity systems around retail facilities and social services. From the analytical fi ndings here, this thesis recognises that there exist relationships between built form confi guration and socio-economic activities occurring in public space. In light of the above, the thesis employs the combination of the visual artistic and social usage approaches to form the making places approach, which can be appropriate for Urban Design in developing cities. After establishing a new approach, the thesis structures the above-mentioned operations into an evolved conceptual framework. Thus, the conceptual framework recognises that time change in developing cities in conjunction with population density and migration cause overlapping relationships between building density, housing and social services, retailing, land use mixes, transport/movement and street connectivity across various scales and within the formal, semi-formal/semiinformal and informal realms. With this being the case, the thesis analyses current literature which argues that the broader problem is the fact that the interrelatedness of the above-mentioned concepts is negated in theory. It develops the problem statement further by stating that a lack of the interrelatedness of the concepts contained in the conceptual framework has in turn infl uenced a lack of such in current research and urban design practice in developing cities. This is confi rmed through measuring the extent to which three South African Urban Design practice case studies consider concepts of building density, housing and social services, retailing, land use mixes, transport/movement and street connectivity across various scales and acknowledging the lack thereof. As a means of responding to the problem identifi ed above, a set of research techniques is investigated using a Yeoville/Bellevue, Johannesburg site-specifi c case with the aim of assisting designers to better apply the evolved conceptual framework. Simultaneously, the thesis uses Yeoville/Bellevue as a focus area to illustrate the manner in which building density, housing and social services, retailing, land use mixes, transport/movement and street connectivity can be considered across various scales. This essentially progresses into the creation of an Urban Design Framework for Yeoville/Bellevue that strengthens the linkages between housing and social services, retailing and transport/movement through using principles of street connectivity, land use mix and building density creation. An implementation strategy for the Design Framework is then established. Through the execution of the above process the collective consideration of building density, housing and social services, retailing, land use mixes, transport/movement and street connectivity across various scales serves as the basis for reframing Urban Design to suit developing cities

Safety and Reliability - Safe Societies in a Changing World

The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management - mathematical methods in reliability and safety - risk assessment - risk management - system reliability - uncertainty analysis - digitalization and big data - prognostics and system health management - occupational safety - accident and incident modeling - maintenance modeling and applications - simulation for safety and reliability analysis - dynamic risk and barrier management - organizational factors and safety culture - human factors and human reliability - resilience engineering - structural reliability - natural hazards - security - economic analysis in risk managemen

Volume 1 – Symposium

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group A: Materials Group B: System design & integration Group C: Novel system solutions Group D: Additive manufacturing Group E: Components Group F: Intelligent control Group G: Fluids Group H | K: Pumps Group I | L: Mobile applications Group J: Fundamental