Comparative Study of Railway Drive Systems Using Bond-Graph

Since the first railways were built, they have not ceased to increase their capacity for transport, speed and energy consumption. This paper presents a comparative study of how present-day railway drive systems perform. Special emphasis is placed on consumption and energy efficiency. By using theoretical computer simulation models, simulations are conducted of the performance of present-day railway drive systems under certain specific boundary conditions. Bond-Graph Technique has been used to design the models. This technique is widely known and accepted for its suitability and capability for modeling dynamic systems in any field of science or technology, and particularly for modeling vehicular systems. Modeling is done systematically taking account of all the mechanical, dynamic, electrical, electromagnetic and regulation phenomena involved in the operation of railway drive systems. A detailed study of the simulation results has enabled a comparative analysis to be conducted of the most significant variables. Important conclusions have been drawn from this analysis about the drive systems that have been shown to be comparatively more efficient

Detection of Communities within the Multibody System Dynamics Network and Analysis of Their Relations

Multibody system dynamics is already a well developed branch of theoretical, computational and applied mechanics. Thousands of documents can be found in any of the well-known scientific databases. In this work it is demonstrated that multibody system dynamics is built of many thematic communities. Using the Elsevier’s abstract and citation database SCOPUS, a massive amount of data is collected and analyzed with the use of the open source visualization tool Gephi. The information is represented as a large set of nodes with connections to study their graphical distribution and explore geometry and symmetries. A randomized radial symmetry is found in the graphical representation of the collected information. Furthermore, the concept of modularity is used to demonstrate that community structures are present in the field of multibody system dynamics. In particular, twenty-four different thematic communities have been identified. The scientific production of each community is analyzed, which allows to predict its growing rate in the next years. The journals and conference proceedings mainly used by the authors belonging to the community as well as the cooperation between them by country are also analyzed

Modeling and Simulation in Engineering

This book provides an open platform to establish and share knowledge developed by scholars, scientists, and engineers from all over the world, about various applications of the modeling and simulation in the design process of products, in various engineering fields. The book consists of 12 chapters arranged in two sections (3D Modeling and Virtual Prototyping), reflecting the multidimensionality of applications related to modeling and simulation. Some of the most recent modeling and simulation techniques, as well as some of the most accurate and sophisticated software in treating complex systems, are applied. All the original contributions in this book are jointed by the basic principle of a successful modeling and simulation process: as complex as necessary, and as simple as possible. The idea is to manipulate the simplifying assumptions in a way that reduces the complexity of the model (in order to make a real-time simulation), but without altering the precision of the results

Foreign banks’ attraction to the financial centre Frankfurt : a "u"-shaped relationship

This paper traces the location of foreign banks in Germany from 1949 to 2006. As suggested by new economic geography models we find a ‘u’-shaped concentration of foreign banks in Germany. Only after a competition between several cities, Frankfurt has emerged as the pre-eminent financial centre, triggered by the ‘historical event’ of setting up the German central bank in Frankfurt. After a strong increase, Frankfurt’s share in the location of foreign banks in Germany decreases slowly but significantly since the mid 1980’s. We conclude that there will be a lesser role in Europe for secondtier financial centres in the future

An analysis of economic infrastructure investment in South Africa

This paper analyses long-term trends in the development of South Africa's economic infrastructure and how this relates to the country's long-term economic growth. A database covering railways, roads, ports, air travel, phone lines and electricity was established for this purpose, and may facilitate further quantitative research. PSS (Pesaran, Shin and Smith, 1996, 2001) F-tests are used to identify directions of association between economic infrastructure and economic growth. These indicate long-run forcing relationships from public sector economic infrastructure investment and fixed capital stock to gross domestic product (GDP), from roads to GDP, and from GDP to a range of other types of infrastructure. There is also evidence of potential simultaneity between specific types of infrastructure and GDP. The evidence suggests three main findings. Firstly, the relationship between economic infrastructure and economic growth appears to run in both directions. Inadequate investment in infrastructure could create bottlenecks, and opportunities for promoting economic growth could be missed. Secondly, South Africa's stock of economic infrastructure has developed in phases. Policymakers should focus on choosing or encouraging the right type of infrastructure at the right time. Thirdly, the need for investment in economic infrastructure never goes away. The maintenance and expansion of infrastructure are important dimensions of supporting economic activity in a growing economy, provided that individual projects are chosen on the basis of appropriate cost-benefit analyses

Stock Markets and Business Cycle Comovement in Germany before World War I: Evidence from Spectral Analysis

This paper examines the comovement of the stock market and of real activity in Germany before World War I under the effcient market hypothesis. We employ multivariate spectral analysis to compare rivaling national product estimates to stock market behavior in the frequency domain. Close comovement of one series with the stock market enables us to decide between various rivaling business cycle chronologies. We find that business cycle dates obtained from deflated national product series are severely distorted by interference with the implicit price deflator. Among the nominal series, the income estimate of Hoffmann (1965) correlates best with the stock market, while the tax based estimate of Hoffmann and Müller (1959) is too smooth especially before 1890. We find impressive comovement between the stock market and nominal wages, a sub-series of Hoffmann's income estimate. We can show that a substantial part of this nominal wage series is driven by data on real investment activity. Our findings confirm the traditional business cycle chronology for Germany of Burns and Mitchell (1946) and Spiethoff (1955), and lead us to discard later, rivaling business cycle chronologies.Business Cycle Chronology, Imperial Germany, Spectral Analysis, Effcient Market Hypothesis

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

Rail: African & African American Labor and the Ties That Bind in the Atlantic World

As was intended, the construction of railways transformed the landscape and societies of the Atlantic World. Great fortunes and forces emerged in the directions of the tracks, sufficient to create structures of economy and organize communities in ways that persisted long after a railway’s use had diminished. In this dissertation, the author argues that the connections and reorganization effected by railway construction created new economic paths in the American South, Panama, and Gold Coast West Africa; the transformations were marked by struggles for power along racial lines, enslavement and coercion in labor, and the interchange between communities and their existing markets and a largely foreign, imperial order. Using sources from African Americans, Afro-Caribbean, and West Africans who comprised the bulk of the labor, as well as the communities where the railways were constructed, the author combines these with geographical and statistical data to portray an environment where whole societies were in flux. While the African Americans in the South experienced a retrenchment of racism in the form of segregation – often following railroad tracks – Afro-Caribbean laborers dug a Panamanian thoroughfare that bolstered European trade, and West Africans laid the tracks for gold and cocoa to the Atlantic Coast. The author concludes that, in addition to the power and persistence conferred by railways, they grant us the opportunity to realize the importance of connections created by communities, and how they were affected by the tracks that ran through them or passed them by. Connections can also provide a refreshing focus in historical methodology; in their persistence, how they are readily revealed by a multitude of sources, and how they amply represent human movement and interaction rather than typical historical emphasis on spatial entities provides a template for exploring reflexive, illustrative approaches to history