Stochastic Delay Prediction in Large Train Networks

In daily operation, railway traffic always deviates from the planned schedule to a certain extent. Primary initial delays of trains may cause a whole cascade of secondary delays of other trains over the entire network. In this paper, we propose a stochastic model for delay propagation and forecasts of arrival and departure events which is applicable to all kind of public transport (not only to railway traffic). Our model is fairly realistic, it includes general waiting policies (how long do trains wait for delayed feeder trains), it uses driving time profiles (discrete distributions) on travel arcs which depend on the departure time, and it incorporates the catch-up potential of buffer times on driving sections and train stops. The model is suited for an online scenario where a massive stream of update messages on the current status of trains arrives which has to be propagated through the whole network. Efficient stochastic propagation of delays has important applications in online timetable information, in delay management and train disposition, and in stability analysis of timetables. The proposed approach has been implemented and evaluated on the German timetable of 2011 with waiting policies of Deutsche Bahn AG. A complete stochastic delay propagation for the whole German train network and a whole day can be performed in less than 14 seconds on a PC. We tested our propagation algorithm with artificial discrete travel time distributions which can be parametrized by the size of their fluctuations. Our forecasts are compared with real data. It turns out that stochastic propagation of delays is efficient enough to be applicable in practice, but the forecast quality requires further adjustments of our artificial travel time distributions to estimates from real data

The correlation between black hole mass and bulge velocity dispersion in hierarchical galaxy formation models

Recent work has demonstrated that there is a tight correlation between the mass of a black hole and the velocity dispersion of the bulge of its host galaxy. We show that the model of Kauffmann & Haehnelt, in which bulges and supermassive black holes both form during major mergers, produces a correlation between M_bh and sigma with slope and scatter comparable to the observed relation. In the model, the M_bh - sigma relation is significantly tighter than the correlation between black hole mass and bulge luminosity or the correlation between bulge luminosity and velocity dispersion. There are two reasons for this: i) the gas masses of bulge progenitors depend on the velocity dispersion but not on the formation epoch of the bulge, whereas the stellar masses of the progenitors depend on both; ii) mergers between galaxies move black holes along the observed M_bh - sigma relation, even at late times when the galaxies are gas-poor and black holes grow mainly by merging of pre-existing black holes. We conclude that the small scatter in the observed M_bh - sigma relation is consistent with a picture in which bulges and black holes form over a wide range in redshift.Comment: 5 pages, LaTeX, 3 postscript figures included; submitted to MNRA

Bietet der Kompromiss zur EU-Dienstleistungsrichtlinie eine akzeptable Lösung?

Die von der Europäischen Kommission vorgeschlagene radikale Öffnung der Dienstleistungsmärkte in Europa ist gescheitert. Das Europäische Parlament einigte sich auf eine Entschärfung der Richtlinie. Dieser Kompromiss ist für Evelyne Gebhardt, Mitglied des Europäischen Parlaments, "… ein Kompromiss, der als Grundlage für eine faire und sozial ausgewogene Öffnung der Dienstleistungsmärkte dienen kann. Die Freizügigkeit für Dienstleistungen wird sichergestellt. Gleichzeitig bleiben die in den Mitgliedstaaten bestehenden Standards und Bestimmungen bei wichtigen Fragen der Daseinsvorsorge, des Arbeitsrechtes, des Verbraucher-, Umwelt- und Patientenschutzes gewahrt." Sie unterstreicht vor allem die besondere Bedeutung des Wegfalls des Herkunftslandprinzips und betont, dass durch den jetzigen Vorschlag "der Marktzugang erleichtert wird und zugleich die Bestimmungen und Standards des Ziellandes respektiert werden müssen". Aus Sicht von Martin Wansleben, Deutscher Industrie- und Handelskammertag, bietet der Kompromiss zur Dienstleistungsrichtlinie "keinen Anlass zur Freude. Denn die Chance, den Binnenmarkt bei vorübergehenden Dienstleistungserbringungen zu verwirklichen und damit das Wachstum der Mitgliedstaaten zu stärken, wurde der Angst vor Veränderung und dem Misstrauen gegenüber den anderen Mitgliedstaaten geopfert. … Mit der starken Verwässerung des Herkunftslandprinzips fallen die positiven ökonomischen Effekte für den europäischen Wirtschaftsraum weitestgehend weg. Hintertüren für Protektionismus sind nach wie vor vorhanden." Auch für Klaus Bräunig, Bundesverband der Deutschen Industrie, ist der Kompromiss nicht "der erhoffte großen Wurf zur Liberalisierung des europäischen Dienstleistungsmarktes".EU-Vergaberecht, Dienstleistungssektor, Unternehmen, Branche, Deutschland, EU-Staaten

Improved variational principle for bounds on energy dissipation in turbulent shear flow

We extend the Doering-Constantin approach to upper bounds on energy dissipation in turbulent flows by introducing a balance parameter into the variational principle. This parameter governs the relative weight of different contributions to the dissipation rate. Its optimization leads to improved bounds without entailing additional technical difficulties. For plane Couette flow, the high-Re-bounds obtainable with one-dimensional background flows are methodically lowered by a factor of 27/32.Comment: 15 pages, RevTeX, 3 postscript figure

Codebook and Documentation of the Panel Study ‘Labour Market and Social Security’ (PASS) : Datenreport Wave 3

"This wave-specific Datenreport aims to document the wave-related aspects of the study4. Following a short overview of the innovations and characteristics of the third wave (Chapter 1.3.), the key figures on samples and response rates of the third wave are reported (Chapter 2). Moreover, the steps of data preparation and the decisions made as part of this process are described (Chapter 5) and an overview of the variables generated is presented (Chapter 4). Additionally, the weighing procedure is presented (Chapter 6). The separate table reports list the frequencies of all variables included in the scientific use file that were recorded in wave 3, divided into their respective datasets (Volume II to Volume V)." (Author's abstract, IAB-Doku) ((en)) Additional Information Table report II table report III table report IV table report V Questionaires third wave working tools further information german version of this "Datenreport"IAB-Haushaltspanel, Datenaufbereitung, Datenorganisation, Datenzugang, Datenqualität, Datensatzbeschreibung, Erhebungsmethode, Stichprobe, personenbezogene Daten, private Haushalte, Alterssicherung

Non-linear aeroelastic behavior of large horizontal-axis wind turbines:A multibody system approach

In this paper, we present the development of a rigid-flexible multibody model which, coupled with an existing aerodynamic model, is used to numerically simulate the non-linear aeroelastic behavior of large horizontal-axis wind turbines. The model is rather general, different configurations could be easily simulated though it is primarily intended to be used as a research tool to investigate influences of different dynamic aspects. It includes: i) a supporting tower; ii) a nacelle which contains the electricity generator, the power electronics and the control systems; iii) a hub, where the blades are fixed, connected to the generator rotating shaft; and, iv) three blades which extract energy from the airstream. The blades are considered flexible, and their equations of motion are discretized in space domain by using beam finite elements capable of taking into account the non-linearities coming from the kinematics. The tower is also considered flexible, but its equations of motion are discretized by using the method of assumed-modes. The nacelle and hub are considered rigid, and their equations of motion take into account the effects of the kinematic non-linearities. Due to the system complexity, the tower, nacelle and hub are modeled as a single kinematic chain and each blade is modeled separately. Constraint equations are used to connect the blades to the hub. The resulting governing equations are differential-algebraic, and these are numerically and interactively solved in the time domain by using a fourth order predictor-corrector scheme. The results help to understand the wind speed influence on: i) the rotor angular speed; ii) the after-forward and side-to-side displacements of the tower; and, iii) the flap- and edge-wise displacements of the blades. © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Fil: Gebhardt, Cristian Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Estructuras; ArgentinaFil: Preidikman, Sergio. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: M. H. Jørgensen. Aalborg University; DinamarcaFil: Massa, Julio Cesar. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentin

Coordination isomerism in N-heterocyclic phosphenium thiocyanates

Two N-heterocyclic phosphines with exocyclic SCN substituents were synthesised via metathesis of chlorophosphine precursors with KSCN and fully characterised. The crystallographic studies reveal that the products exhibit pronounced structural differences. The thiocyanato unit binds in one case via the nitrogen atom to yield a molecular structure with a slightly elongated P-N single bond and, in the other case, via the sulfur atom to form a structure that is best described as an ion pair and forms a one-dimensional coordination polymer in the crystal. DFT calculations suggest that the P-N and P center dot center dot center dot S interactions can be described as covalent and dative bonds, respectively, and that the structural differences correlate with the different cation stabilities of the individual phosphenium cation fragments.Peer reviewe