A Survey of Wireless Communication Technologies & Their Performance for High Speed Railways

High Speed Railway (HSR) provides its customers not only safety, security, comfort and on-time commuting, but also a fast transportation alternative to air travel or regular passenger rail services. Providing these benefits would not be possible without the tremendous growth and prevalence of wireless communication technologies. Due to advances in wireless communication systems, both trains and passengers are connected through high speed wireless networks to the Internet, data centers and railroad control centers. Railroad communities, academia, related industries and standards bodies, even the European Space Agency, are involved in advancing developments of HSR for highly connected train communication systems. The goal of these efforts is to provide the capabilities for uninterrupted high-speed fault-tolerant communication networks for all possible geographic, structural and weather conditions. This survey provides an overview of the current state-of-the-art and future trends for wireless technologies aiming to realize the concept of HSR communication services. Our goal is to highlight the challenges for these technologies, including GSM-R, Wi-Fi, WIMAX, LTE-R, RoF, LCX & Cognitive Radio, the offered solutions, their performance, and other related issues. Currently, providing HSR services is the goal of many countries across the globe. Europe, Japan & Taiwan, China, as well as North & South America have increased their efforts to advance HSR technologies to monitor and control not only the operations but also to deliver extensive broadband solutions to passengers. This survey determined a trend of the industry to transition control plane operations towards narrowband frequencies, i.e. LTE400/700, and to utilize concurrently other technologies for broadband access for passengers such that services of both user and train control systems are supported. With traditional technologies, a tradeoff was required and often favored train control services over passenger amenities. However, with the advances in communication systems, such as LTE-R and cognitive radios, it is becoming possible for system designers to offer rich services to passengers while also providing support for enhanced train control operations such as Positive Train Control

A Survey of Wireless Communication Technologies & Their Performance for High Speed Railways

High Speed Railway (HSR) provides its customers not only safety, security, comfort and on-time commuting, but also a fast transportation alternative to air travel or regular passenger rail services. Providing these benefits would not be possible without the tremendous growth and prevalence of wireless communication technologies. Due to advances in wireless communication systems, both trains and passengers are connected through high speed wireless networks to the Internet, data centers and railroad control centers. Railroad communities, academia, related industries and standards bodies, even the European Space Agency, are involved in advancing developments of HSR for highly connected train communication systems. The goal of these efforts is to provide the capabilities for uninterrupted high-speed fault-tolerant communication networks for all possible geographic, structural and weather conditions. This survey provides an overview of the current state-of-the-art and future trends for wireless technologies aiming to realize the concept of HSR communication services. Our goal is to highlight the challenges for these technologies, including GSM-R, Wi-Fi, WIMAX, LTE-R, RoF, LCX & Cognitive Radio, the offered solutions, their performance, and other related issues. Currently, providing HSR services is the goal of many countries across the globe. Europe, Japan & Taiwan, China, as well as North & South America have increased their efforts to advance HSR technologies to monitor and control not only the operations but also to deliver extensive broadband solutions to passengers. This survey determined a trend of the industry to transition control plane operations towards narrowband frequencies, i.e. LTE400/700, and to utilize concurrently other technologies for broadband access for passengers such that services of both user and train control systems are supported. With traditional technologies, a tradeoff was required and often favored train control services over passenger amenities. However, with the advances in communication systems, such as LTE-R and cognitive radios, it is becoming possible for system designers to offer rich services to passengers while also providing support for enhanced train control operations such as Positive Train Control

Sustainability and Related Factors of High Speed Railways

High-Speed Railways (HSR), which represent a safe and sustainable mode of transportation, provide access and mobility for the society, and support the growth of the economy in addition to creating new jobs, supporting welfare, and promoting local business activities. This research addresses the shortage of knowledge in evaluating the performance of selected HSR systems and in distinguishing the factors that contribute to the sustainable performance of HSRs. The aim of this study is to evaluate the sustainability of selected HSRs and identify factors that affect such sustainability. The objectives of this research are to evaluate productivity, technical and technological efficiency of the selected HSRs, define the factors that can affect productivity and efficiency scores and make suggestions for improving the sustainability of HSRs. The secondary data methodology has been used, supported by empirical evidence. Most of the data was gathered from the Internet, research in depth of the high-speed railways in the selected countries, and International Union of Railway’s websites in addition to analysing railway statistics and data from European and institutional publications. This includes the use of a multi-stage approach of applying three specialised software packages, namely, NVivo, DEA, and ISM SPSS. The main findings show that HSRs in Asia has higher productivity and higher efficiency scores than that of HSRs in Europe. The research found that the key factors among all the identified factors that affected the productivity and efficiency of HSRs are; density of population, average traction power of HSR trains, average time that passengers spend on trains and average distance that passengers travel on the HSR. The findings of this research can help develop strategic guidelines to improve the performance and, by the result, the sustainability of HSRs. The recommendations are drawn for more research expansion, including the consideration of other HSRs, particularly their best practices

Benchmarking operation readiness of the high-speed rail (HSR) network

At present, HSR networks have been significantly extended to accommodate increased passenger demand because the service is believed to unleash social benefits. Nevertheless, the investment in the HSR project is substantially higher than in other transportation projects. Also, most of the HSR network has faced unavoidable issues during operation, such as lack of passenger demand, low operating profit, and non-safety issues. Despite issues addressed, HSR organisations could not maintain their performance to reach the standard and the globe’s directions, especially the sustainability pillar. Those issues become ineffective for HSR organisations, impacting the passenger’s quality of life and socio-economic. This thesis aims to develop a systems-based benchmarking framework for all HSR networks to enhance operating costs, punctuality, productivity, risk and uncertainty, sustainability, and urbanisation efficiency. Those six KPIs are necessary for the sustainable development of the upcoming HSR network. The thesis has made several significant contributions to developing a benchmarking framework for long-term improvement. First, this thesis is the world’s first to integrate a Bayesian distribution and Python programming to improve safety across the railway network. As a result, the created model shows higher accuracy than previous models due to the combination of long-term data sets. Moreover, this thesis reveals the decision tree and the Petri-net models to identify the risk level. Thus, it is an advantage for the rail authorities to evaluate and enhance safety performance. Next, the thesis focuses on life cycle assessment (LCA) and life cycle cost (LCC) frameworks. The LCA model reflects the environmental perspectives of each rail network. This thesis provides an in-depth analysis of each life cycle stage that shows the energy consumption rate and CO2 emission rate. The outcome can point out energy consumption and CO2 emission performance. In addition, this thesis is the world's first study concerning uncertainty costs during HSR operations regarding the LCC analysis. The net present value calculation with a discount rate has been added with the Monte Carlo Simulation. In this section, the developed model allows HSR authorities to firmly manage the budget under uncertain conditions, especially during an operating stage. Lastly, this thesis concentrates on the social impacts of HSR service, particularly on a living quality, educational benefits, and economic opportunities. The long-term datasets have been analysed by using K-nearest neighbour and Pearson correlation techniques. The result can point out the company’s performance toward social advantages. By adopting the models in practice, people can obtain more benefits from the HSR service. By promoting the novelty framework into practice, benchmarking through diversification of current HSR networks is addressed. The selected routes and networks are chosen using a range of factors. For illustrate, the collected networks must be stable and trustworthy, as determined by their long-term operation for at least ten years. Furthermore, the selected HSR lines are mixed in geography, technology, and relevant conditions to avoid bias. The five noteworthy networks and routes consist of Beijing-Shanghai (China), Paris-Lyon (France), Tokyo-Osaka (Japan), Madrid-Barcelona (Spain), and Seoul-Busan (South Korea). The analysis results indicate that none of the HSR networks illustrates high performance in all pillars. An overview result demonstrates that the CR’s networks perform the best performance following the Renfe, SNCF, JR Central, and Korail networks. In addition, the thesis has provided policy implications for long-term development, in particular, safety services, social impacts, environmental impacts, and technology and innovation. Those suggestions can be applied practically to both existing and upcoming HSR networks

Fault-tolerant software: dependability/performance trade-offs, concurrency and system support

PhD ThesisAs the use of computer systems becomes more and more widespread in applications that demand high levels of dependability, these applications themselves are growing in complexity in a rapid rate, especially in the areas that require concurrent and distributed computing. Such complex systems are very prone to faults and errors. No matter how rigorously fault avoidance and fault removal techniques are applied, software design faults often remain in systems when they are delivered to the customers. In fact, residual software faults are becoming the significant underlying cause of system failures and the lack of dependability. There is tremendous need for systematic techniques for building dependable software, including the fault tolerance techniques that ensure software-based systems to operate dependably even when potential faults are present. However, although there has been a large amount of research in the area of fault-tolerant software, existing techniques are not yet sufficiently mature as a practical engineering discipline for realistic applications. In particular, they are often inadequate when applied to highly concurrent and distributed software. This thesis develops new techniques for building fault-tolerant software, addresses the problem of achieving high levels of dependability in concurrent and distributed object systems, and studies system-level support for implementing dependable software. Two schemes are developed - the t/(n-l)-VP approach is aimed at increasing software reliability and controlling additional complexity, while the SCOP approach presents an adaptive way of dynamically adjusting software reliability and efficiency aspects. As a more general framework for constructing dependable concurrent and distributed software, the Coordinated Atomic (CA) Action scheme is examined thoroughly. Key properties of CA actions are formalized, conceptual model and mechanisms for handling application level exceptions are devised, and object-based diversity techniques are introduced to cope with potential software faults. These three schemes are evaluated analytically and validated by controlled experiments. System-level support is also addressed with a multi-level system architecture. An architectural pattern for implementing fault-tolerant objects is documented in detail to capture existing solutions and our previous experience. An industrial safety-critical application, the Fault-Tolerant Production Cell, is used as a case study to examine most of the concepts and techniques developed in this research.ESPRIT

Entwicklung und Analyse eines Zug-zentrischen Entfernungsmesssystems mittels Colored Petri Nets

Based on the technology trends, the train control system should weaken the proportion of ground facilities, and give trains more individual initiative than in the past. As a result, the safety and flexibility of the train control system can be further improved. In this thesis, an enhanced movement authority system is proposed, which combines advantages of the train-centric communication with current movement authority mechanisms. To obtain the necessary train distance interval data, the onboard equipment and a new train-to-train distance measurement system (TTDMS) are applied as normal and backup strategies, respectively. While different location technologies have been used to collect data for trains, the development and validation of new systems remain challenges. In this thesis, formal approaches are presented for developing and verifying TTDMS. To assist the system development, the Colored Petri nets (CPNs) are used to formalize and evaluate the system structure and its behavior. Based on the CPN model, the system structure is validated. Additionally, a procedure is proposed to generate a Code Architecture from the formal model. The system performance is assessed in detection range and accuracy. Therefore both mathematical simulation and practical measurements validation are implemented. The results indicate that the system is feasible to carry out distance measurements both in metropolitan and railway lines, and the formal approaches are reusable to develop and verify other systems. As the target object, TTDMS is based on a spread-spectrum technology to accomplish distance measurement. The measurement is carried out by applying Time of Arrival (TOA) to calculate the distance between two trains, and requires no synchronized time source of transmission. It can calculate the time difference by using the autocorrelation of Pseudo Random Noise (PRN) code. Different from existing systems in air and maritime transport, this system does not require any other localization unit, except for communication architecture. To guarantee a system can operate as designed, it needs to be validated before its application. Only when system behaviors have been validated other relative performances' evaluations make sense. Based on the unambiguous definition of formal methods, TTDMS can be described much clearer by using formal methods instead of executable codes.Basierend auf technologischen Trends sollte das Zugbeeinflussungssystem den Anteil der Bodenanlagen reduzieren und den Zügen mehr Eigeninitiative geben als in der Vergangenheit, da so die funktionale Sicherheit und die Flexibilität des Zugbeeinflussungssystems erhöht werden können. In dieser Arbeit wird ein verbessertes System vorgeschlagen, das die Vorteile der zugbezogenen Kommunikation mit den aktuellen Fahrbefehlsmechanismen kombiniert. Um die notwendigen Daten des Zugabstandsintervalls zu erhalten, werden die Bordausrüstung und ein neues Zug-zu-Zug-Entfernungsmesssystem (TTDMS) als normale bzw. Backup-Strategien angewendet. Während verschiedene Ortungstechnolgien zur Zugdatenerfassung genutzt wurden, bleibt die Entwicklung und Validierung neuer Systeme eine Herausforderung. In dieser Arbeit werden formale Ansätze zur Entwicklung und Verifikation von TTDMS vorgestellt. Zur Unterstützung der Systementwicklung werden CPNs zur Formalisierung und Bewertung der Systemstruktur und ihres Verhaltens eingesetzt. Basierend auf dem CPN-Modell wird die Systemstruktur validiert. Zusätzlich wird eine Methode vorgeschlagen, mit der eine Code-Architektur aus dem formalen Modell generiert werden kann. Die Systemleistung wird im Erfassungsbereich und in der Genauigkeit beurteilt. Daher werden sowohl eine mathematische Simulation als auch eine praktische Validierung der Messungen implementiert. Die Ergebnisse zeigen, dass das System in der Lage ist, Entfernungsmessungen in Metro- und Eisenbahnlinien durchzuführen. Zudem sind die formalen Ansätze bei der Entwicklung und Verifikation anderer Systeme wiederverwendbar. Die Abstandsmessung mit TTDMS basiert auf einem Frequenzspreizungsverfahren. Die Messung wird durchgeführt, indem die Ankunftszeit angewendet wird, um den Abstand zwischen zwei Zügen zu berechnen. Dieses Verfahren erfordert keine Synchronisierung der Zeitquellen der Übertragung. Der Zeitunterschied kann damit berechnet werden, indem die Autokorrelation des Pseudo-Random-Noise-Codes verwendet wird. Im Unterschied zu Systemen im Luft- und Seeverkehr benötigt dieses System keine andere Lokalisierungseinheit als die Kommunikationsarchitektur. Um zu gewährleisten, dass ein System wie vorgesehen funktioniert, muss es validiert werden. Nur wenn das Systemverhalten validiert wurde, sind Bewertungen anderer relativer Leistungen sinnvoll. Aufgrund ihrer eindeutigen Definition kann das TTDMS mit formalen Methoden klarer beschrieben werden als mit ausführbaren Codes

Contributions to the design of power modules for electric and hybrid vehicles: trends, design aspects and simulation techniques

314 p.En la última década, la protección del medio ambiente y el uso alternativo de energías renovables están tomando mayor relevancia tanto en el ámbito social y político, como científico. El sector del transporte es uno de los principales causantes de los gases de efecto invernadero y la polución existente, contribuyendo con hasta el 27 % de las emisiones a nivel global. En este contexto desfavorable, la electrificación de los vehículos de carretera se convierte en un factor crucial. Para ello, la transición de la actual flota de vehículos de carretera debe ser progresiva forzando la investigación y desarrollo de nuevos conceptos a la hora de producir vehículos eléctricos (EV) y vehículos eléctricos híbridos (HEV) más eficientes, fiables, seguros y de menor coste. En consecuencia, para el desarrollo y mejora de los convertidores de potencia de los HEV/EV, este trabajo abarca los siguientes aspectos tecnológicos: - Arquitecturas de la etapa de conversión de potencia. Las principales topologías que pueden ser implementadas en el tren de potencia para HEV/EV son descritas y analizadas, teniendo en cuenta las alternativas que mejor se adaptan a los requisitos técnicos que demandan este tipo de aplicaciones. De dicha exposición se identifican los elementos constituyentes fundamentales de los convertidores de potencia que forman parte del tren de tracción para automoción.- Nuevos dispositivos semiconductores de potencia. Los nuevos objetivos y retos tecnológicos solo pueden lograrse mediante el uso de nuevos materiales. Los semiconductores Wide bandgap (WBG), especialmente los dispositivos electrónicos de potencia basados en nitruro de galio (GaN) y carburo de silicio (SiC), son las alternativas más prometedoras al silicio (Si) debido a las mejores prestaciones que poseen dichos materiales, lo que permite mejorar la conductividad térmica, aumentar las frecuencias de conmutación y reducir las pérdidas.- Análisis de técnicas de rutado, conexionado y ensamblado de módulos de potencia. Los módulos de potencia fabricados con dies en lugar de dispositivos discretos son la opción preferida por los fabricantes para lograr las especificaciones indicadas por la industria de la automoción. Teniendo en cuenta los estrictos requisitos de eficiencia, fiabilidad y coste es necesario revisar y plantear nuevos layouts de las etapas de conversión de potencia, así como esquemas y técnicas de paralelización de los circuitos, centrándose en las tecnologías disponibles.Teniendo en cuenta dichos aspectos, la presente investigación evalúa las alternativas de semiconductores de potencia que pueden ser implementadas en aplicaciones HEV/EV, así como su conexionado para la obtención de las densidades de potencia requeridas, centrándose en la técnica de paralelización de semiconductores. Debido a la falta de información tanto científica como comercial e industrial sobre dicha técnica, una de las principales contribuciones del presente trabajo ha sido la propuesta y verificación de una serie de criterios de diseño para el diseño de módulos de potencia. Finalmente, los resultados que se han extraído de los circuitos de potencia propuestos demuestran la utilidad de dichos criterios de diseño, obteniendo circuitos con bajas impedancias parásitas y equilibrados eléctrica y térmicamente. A nivel industrial, el conocimiento expuesto en la presente tesis permite reducir los tiempos de diseño a la hora de obtener prototipos de ciertas garantías, permitiendo comenzar la fase de prototipado habiéndose realizado comprobaciones eléctricas y térmicas