14 Search Results for "Müller, Ralf"


Volume

OASIcs, Volume 89

2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020)

iPMVM 2020, November 16-18, 2020, Schloss Dagstuhl, Wadern, Germany (Virtual Conference)

Editors: Christoph Garth, Jan C. Aurich, Barbara Linke, Ralf Müller, Bahram Ravani, Gunther H. Weber, and Benjamin Kirsch

Document
On the Origins of Coccinelle

Authors: Julia Lawall

Published in: OASIcs, Volume 109, Eelco Visser Commemorative Symposium (EVCS 2023)


Abstract
Coccinelle is a program-transformation system for C code. It has been under development since 2005 and has been extensively used on the Linux kernel. The design of Coccinelle was inspired in part by the author’s previous experience in using Stratego/XT, developed by Eelco Visser. This paper reflects on some of Coccinelle’s design choices and their relation to Eelco Visser’s work.

Cite as

Julia Lawall. On the Origins of Coccinelle. In Eelco Visser Commemorative Symposium (EVCS 2023). Open Access Series in Informatics (OASIcs), Volume 109, pp. 18:1-18:11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{lawall:OASIcs.EVCS.2023.18,
  author =	{Lawall, Julia},
  title =	{{On the Origins of Coccinelle}},
  booktitle =	{Eelco Visser Commemorative Symposium (EVCS 2023)},
  pages =	{18:1--18:11},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-267-9},
  ISSN =	{2190-6807},
  year =	{2023},
  volume =	{109},
  editor =	{L\"{a}mmel, Ralf and Mosses, Peter D. and Steimann, Friedrich},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.EVCS.2023.18},
  URN =		{urn:nbn:de:0030-drops-177884},
  doi =		{10.4230/OASIcs.EVCS.2023.18},
  annote =	{Keywords: Linux kernel, Coccinelle, Stratego/XT, program transformation}
}
Document
Passenger-Aware Real-Time Planning of Short Turns to Reduce Delays in Public Transport

Authors: Julian Patzner, Ralf Rückert, and Matthias Müller-Hannemann

Published in: OASIcs, Volume 106, 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)


Abstract
Delays and disruptions are commonplace in public transportation. An important tool to limit the impact of severely delayed vehicles is the use of short turns, where a planned trip is shortened in order to be able to resume the following trip in the opposite direction as close to the schedule as possible. Short turns have different effects on passengers: some suffer additional delays and have to reschedule their route, while others can benefit from them. Dispatchers therefore need decision support in order to use short turns only if the overall delay of all affected passengers is positively influenced. In this paper, we study the planning of short turns based on passenger flows. We propose a simulation framework which can be used to decide upon single short turns in real time. An experimental study with a scientific model (LinTim) of an entire public transport system for the German city of Stuttgart including busses, trams, and local trains shows that we can solve these problems on average within few milliseconds. Based on features of the current delay scenario and the passenger flow we use machine learning to classify cases where short turns are beneficial. Depending on how many features are used, we reach a correct classification rate of more than 93% (full feature set) and 90% (partial feature set) using random forests. Since precise passenger flows are often not available in urban public transportation, our machine learning approach has the great advantage of working with significantly less detailed passenger information.

Cite as

Julian Patzner, Ralf Rückert, and Matthias Müller-Hannemann. Passenger-Aware Real-Time Planning of Short Turns to Reduce Delays in Public Transport. In 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022). Open Access Series in Informatics (OASIcs), Volume 106, pp. 13:1-13:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{patzner_et_al:OASIcs.ATMOS.2022.13,
  author =	{Patzner, Julian and R\"{u}ckert, Ralf and M\"{u}ller-Hannemann, Matthias},
  title =	{{Passenger-Aware Real-Time Planning of Short Turns to Reduce Delays in Public Transport}},
  booktitle =	{22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)},
  pages =	{13:1--13:18},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-259-4},
  ISSN =	{2190-6807},
  year =	{2022},
  volume =	{106},
  editor =	{D'Emidio, Mattia and Lindner, Niels},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2022.13},
  URN =		{urn:nbn:de:0030-drops-171171},
  doi =		{10.4230/OASIcs.ATMOS.2022.13},
  annote =	{Keywords: Public Transportation, Delays, Real-time Dispatching, Passenger Flows}
}
Document
Towards Improved Robustness of Public Transport by a Machine-Learned Oracle

Authors: Matthias Müller-Hannemann, Ralf Rückert, Alexander Schiewe, and Anita Schöbel

Published in: OASIcs, Volume 96, 21st Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2021)


Abstract
The design and optimization of public transport systems is a highly complex and challenging process. Here, we focus on the trade-off between two criteria which shall make the transport system attractive for passengers: their travel time and the robustness of the system. The latter is time-consuming to evaluate. A passenger-based evaluation of robustness requires a performance simulation with respect to a large number of possible delay scenarios, making this step computationally very expensive. For optimizing the robustness, we hence apply a machine-learned oracle from previous work which approximates the robustness of a public transport system. We apply this oracle to bi-criteria optimization of integrated public transport planning (timetabling and vehicle scheduling) in two ways: First, we explore a local search based framework studying several variants of neighborhoods. Second, we evaluate a genetic algorithm. Computational experiments with artificial and close to real-word benchmark datasets yield promising results. In all cases, an existing pool of solutions (i.e., public transport plans) can be significantly improved by finding a number of new non-dominated solutions, providing better and different trade-offs between robustness and travel time.

Cite as

Matthias Müller-Hannemann, Ralf Rückert, Alexander Schiewe, and Anita Schöbel. Towards Improved Robustness of Public Transport by a Machine-Learned Oracle. In 21st Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2021). Open Access Series in Informatics (OASIcs), Volume 96, pp. 3:1-3:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{mullerhannemann_et_al:OASIcs.ATMOS.2021.3,
  author =	{M\"{u}ller-Hannemann, Matthias and R\"{u}ckert, Ralf and Schiewe, Alexander and Sch\"{o}bel, Anita},
  title =	{{Towards Improved Robustness of Public Transport by a Machine-Learned Oracle}},
  booktitle =	{21st Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2021)},
  pages =	{3:1--3:20},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-213-6},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{96},
  editor =	{M\"{u}ller-Hannemann, Matthias and Perea, Federico},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2021.3},
  URN =		{urn:nbn:de:0030-drops-148721},
  doi =		{10.4230/OASIcs.ATMOS.2021.3},
  annote =	{Keywords: Public Transportation, Timetabling, Machine Learning, Robustness}
}
Document
Complete Volume
OASIcs, Volume 89, iPMVM 2020, Complete Volume

Authors: Christoph Garth, Jan C. Aurich, Barbara Linke, Ralf Müller, Bahram Ravani, Gunther H. Weber, and Benjamin Kirsch

Published in: OASIcs, Volume 89, 2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020)


Abstract
OASIcs, Volume 89, iPMVM 2020, Complete Volume

Cite as

2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020). Open Access Series in Informatics (OASIcs), Volume 89, pp. 1-364, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@Proceedings{garth_et_al:OASIcs.iPMVM.2020,
  title =	{{OASIcs, Volume 89, iPMVM 2020, Complete Volume}},
  booktitle =	{2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020)},
  pages =	{1--364},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-183-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{89},
  editor =	{Garth, Christoph and Aurich, Jan C. and Linke, Barbara and M\"{u}ller, Ralf and Ravani, Bahram and Weber, Gunther H. and Kirsch, Benjamin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.iPMVM.2020},
  URN =		{urn:nbn:de:0030-drops-137486},
  doi =		{10.4230/OASIcs.iPMVM.2020},
  annote =	{Keywords: OASIcs, Volume 89, iPMVM 2020, Complete Volume}
}
Document
Front Matter
Front Matter, Table of Contents, Preface, Conference Organization

Authors: Christoph Garth, Jan C. Aurich, Barbara Linke, Ralf Müller, Bahram Ravani, Gunther H. Weber, and Benjamin Kirsch

Published in: OASIcs, Volume 89, 2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020)


Abstract
Front Matter, Table of Contents, Preface, Conference Organization

Cite as

2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020). Open Access Series in Informatics (OASIcs), Volume 89, pp. 0:i-0:xii, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{garth_et_al:OASIcs.iPMVM.2020.0,
  author =	{Garth, Christoph and Aurich, Jan C. and Linke, Barbara and M\"{u}ller, Ralf and Ravani, Bahram and Weber, Gunther H. and Kirsch, Benjamin},
  title =	{{Front Matter, Table of Contents, Preface, Conference Organization}},
  booktitle =	{2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020)},
  pages =	{0:i--0:xii},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-183-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{89},
  editor =	{Garth, Christoph and Aurich, Jan C. and Linke, Barbara and M\"{u}ller, Ralf and Ravani, Bahram and Weber, Gunther H. and Kirsch, Benjamin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.iPMVM.2020.0},
  URN =		{urn:nbn:de:0030-drops-137497},
  doi =		{10.4230/OASIcs.iPMVM.2020.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
Influence of Flank Face Structuring on Cooling, Tool Lifetime and Borehole Quality When Drilling Inconel 718: Physical Simulations and Experimental Validation

Authors: Daniel Müller, Benjamin Kirsch, and Jan C. Aurich

Published in: OASIcs, Volume 89, 2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020)


Abstract
When drilling difficult-to-cut materials such as Inconel 718, the drills are exposed to high thermomechanical loads. Due to the low thermal conductivity of the workpiece material, a large amount of the generated heat has to be dissipated by the metal working fluid (MWF). However, the cutting zone is located inside the workpiece, which makes it challenging to provide sufficient MWF to the cutting zone. To solve this, drills with internal cooling channels are commonly used. In this work, the influence of differently structured flank faces on cooling efficiency, tool life, process forces and borehole quality is investigated. The influence of the structures on the cooling was investigated by Computational-Fluid-Dynamics (CFD) simulations. These simulations allow a detailed analysis of the flow conditions inside the borehole and showed that the structuring improved flow conditions, especially near the thermally highly loaded main cutting edge. The improved flow conditions resulted in an extension of the tool life by up to 22 % compared to unstructured drills in experimental investigations.

Cite as

Daniel Müller, Benjamin Kirsch, and Jan C. Aurich. Influence of Flank Face Structuring on Cooling, Tool Lifetime and Borehole Quality When Drilling Inconel 718: Physical Simulations and Experimental Validation. In 2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020). Open Access Series in Informatics (OASIcs), Volume 89, pp. 7:1-7:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{muller_et_al:OASIcs.iPMVM.2020.7,
  author =	{M\"{u}ller, Daniel and Kirsch, Benjamin and Aurich, Jan C.},
  title =	{{Influence of Flank Face Structuring on Cooling, Tool Lifetime and Borehole Quality When Drilling Inconel 718: Physical Simulations and Experimental Validation}},
  booktitle =	{2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020)},
  pages =	{7:1--7:17},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-183-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{89},
  editor =	{Garth, Christoph and Aurich, Jan C. and Linke, Barbara and M\"{u}ller, Ralf and Ravani, Bahram and Weber, Gunther H. and Kirsch, Benjamin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.iPMVM.2020.7},
  URN =		{urn:nbn:de:0030-drops-137562},
  doi =		{10.4230/OASIcs.iPMVM.2020.7},
  annote =	{Keywords: drilling, cooling, CFD}
}
Document
A Phase Field Modeling Approach of Crack Growth in Materials with Anisotropic Fracture Toughness

Authors: Christoph Schreiber, Tim Ettrich, Charlotte Kuhn, and Ralf Müller

Published in: OASIcs, Volume 89, 2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020)


Abstract
Within this contribution, we present a diffuse interface approach for the simulation of crack nucleation and growth in materials, which incorporates an orientation dependency of the fracture toughness. After outlining the basic motivation for the model from an engineering standpoint, the phase field paradigm for fracture is introduced. Further, a specific phase field model for brittle fracture is reviewed, where we focus on the meaning of the auxiliary parameter differentiating between material phases and the coupling of such a parameter to continuum equations in order to obtain the characteristic self organizing model properties. This specific model, as will be explained, provides the phenomenological and methodical basis for the presented enhancement. The formulation of an appropriate evolution equation in terms of a Ginzburg-Landau type equation will be highlighted and several comments on sharp interface models will be made to present a brief comparison. Following up on the basics we then introduce the formulation of a modified version of the model, which additionally to the handling of cracks in linear elastic materials under quasi static loading is also capable of taking into account the effect of resistance variation with respect to the potential crack extension direction. The strong and also the weak forms of the respective governing equations corresponding to the developed anisotropic phase field model are presented. Utilizing the weak formulation as starting point for the discretization of the two fields (displacement field and the phase field), the computational framework in terms of finite elements is introduced. We finally explain several test cases investigated within simulations and discuss the corresponding numerical results. Besides examples, which are set up to illustrate the general model properties, a comparison with crack paths obtained by experimental investigations will be presented in order to show the potential of the developed phase field model.

Cite as

Christoph Schreiber, Tim Ettrich, Charlotte Kuhn, and Ralf Müller. A Phase Field Modeling Approach of Crack Growth in Materials with Anisotropic Fracture Toughness. In 2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020). Open Access Series in Informatics (OASIcs), Volume 89, pp. 9:1-9:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{schreiber_et_al:OASIcs.iPMVM.2020.9,
  author =	{Schreiber, Christoph and Ettrich, Tim and Kuhn, Charlotte and M\"{u}ller, Ralf},
  title =	{{A Phase Field Modeling Approach of Crack Growth in Materials with Anisotropic Fracture Toughness}},
  booktitle =	{2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020)},
  pages =	{9:1--9:17},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-183-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{89},
  editor =	{Garth, Christoph and Aurich, Jan C. and Linke, Barbara and M\"{u}ller, Ralf and Ravani, Bahram and Weber, Gunther H. and Kirsch, Benjamin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.iPMVM.2020.9},
  URN =		{urn:nbn:de:0030-drops-137581},
  doi =		{10.4230/OASIcs.iPMVM.2020.9},
  annote =	{Keywords: Phase field modeling, Brittle fracture, Anisotropic fracture toughness, Finite elements}
}
Document
An Improved Particle Finite Element Method for the Simulation of Machining Processes

Authors: Xialong Ye, Juan Manuel Rodríguez Prieto, and Ralf Müller

Published in: OASIcs, Volume 89, 2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020)


Abstract
Machining is one of the most common and versatile manufacturing processes in industry, e.g. automotive industry and aerospace industry. But classical numerical methods such as the Finite Element Method (FEM) have difficulties to simulate it, because the material undergoes large deformations, large strain, large strain rates and high temperatures in this process. One option to simulate such kind of problems is the Particle Finite Element Method (PFEM) which combines the advantages of continuum mechanics and discrete modeling techniques. In this study we develop the PFEM further and call it the Adaptive Particle Finite Element Method (A-PFEM). Compared to the PFEM the A-PFEM enables insertion of particles and improves significantly the mesh quality along the numerical simulation. The A-PFEM improves accuracy and precision, while it decreases computing time and resolves the phenomena that take place in machining. Because metal cutting involves plastic deformation we resort to the J₂ flow theory with isotropic hardening. At last some numerical examples are presented to compare the performance of the PFEM and A-PFEM.

Cite as

Xialong Ye, Juan Manuel Rodríguez Prieto, and Ralf Müller. An Improved Particle Finite Element Method for the Simulation of Machining Processes. In 2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020). Open Access Series in Informatics (OASIcs), Volume 89, pp. 13:1-13:9, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{ye_et_al:OASIcs.iPMVM.2020.13,
  author =	{Ye, Xialong and Prieto, Juan Manuel Rodr{\'\i}guez and M\"{u}ller, Ralf},
  title =	{{An Improved Particle Finite Element Method for the Simulation of Machining Processes}},
  booktitle =	{2nd International Conference of the DFG International Research Training Group 2057 – Physical Modeling for Virtual Manufacturing (iPMVM 2020)},
  pages =	{13:1--13:9},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-183-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{89},
  editor =	{Garth, Christoph and Aurich, Jan C. and Linke, Barbara and M\"{u}ller, Ralf and Ravani, Bahram and Weber, Gunther H. and Kirsch, Benjamin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.iPMVM.2020.13},
  URN =		{urn:nbn:de:0030-drops-137628},
  doi =		{10.4230/OASIcs.iPMVM.2020.13},
  annote =	{Keywords: Particle Finite Element Method, Alpha Shape Method, Metal Cutting}
}
Document
Vehicle Capacity-Aware Rerouting of Passengers in Delay Management

Authors: Matthias Müller-Hannemann, Ralf Rückert, and Sebastian S. Schmidt

Published in: OASIcs, Volume 75, 19th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2019)


Abstract
Due to the significant growth in passenger numbers, higher vehicle load factors and crowding become more and more of an issue in public transport. For safety reasons and because of an unsatisfactory discomfort, standing of passengers is rather limited in high-speed long-distance trains. In case of delays and (partially) cancelled trains, many passengers have to be rerouted. State-of-the-art rerouting merely focuses on minimizing delay at the destination of affected passengers but neglects limited vehicle capacities and crowding. Not considering capacities allows using highly efficient shortest path algorithms like RAPTOR or the connection scan algorithm (CSA). In this paper, we study the more complicated scenario where passengers compete for scarce capacities. This can be modeled as a piece-wise linear, convex cost multi-source multi-commodity unsplittable flow problem where each passenger group which has to be rerouted corresponds to a commodity. We compare a path-based integer linear programming (ILP) model with a heuristic greedy approach. In experiments with instances from German long-distance train traffic, we quantify the importance of considering vehicle capacities in case of train cancellations. We observe a tradeoff: The ILP approach slightly outperforms the greedy approach and both are much better than capacity unaware rerouting in quality, while the greedy algorithm runs more than three times faster.

Cite as

Matthias Müller-Hannemann, Ralf Rückert, and Sebastian S. Schmidt. Vehicle Capacity-Aware Rerouting of Passengers in Delay Management. In 19th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2019). Open Access Series in Informatics (OASIcs), Volume 75, pp. 7:1-7:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)


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@InProceedings{mullerhannemann_et_al:OASIcs.ATMOS.2019.7,
  author =	{M\"{u}ller-Hannemann, Matthias and R\"{u}ckert, Ralf and Schmidt, Sebastian S.},
  title =	{{Vehicle Capacity-Aware Rerouting of Passengers in Delay Management}},
  booktitle =	{19th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2019)},
  pages =	{7:1--7:14},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-128-3},
  ISSN =	{2190-6807},
  year =	{2019},
  volume =	{75},
  editor =	{Cacchiani, Valentina and Marchetti-Spaccamela, Alberto},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2019.7},
  URN =		{urn:nbn:de:0030-drops-114192},
  doi =		{10.4230/OASIcs.ATMOS.2019.7},
  annote =	{Keywords: Delay management, passenger flows, vehicle capacities, rerouting}
}
Document
Robustness as a Third Dimension for Evaluating Public Transport Plans

Authors: Markus Friedrich, Matthias Müller-Hannemann, Ralf Rückert, Alexander Schiewe, and Anita Schöbel

Published in: OASIcs, Volume 65, 18th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2018)


Abstract
Providing attractive and efficient public transport services is of crucial importance due to higher demands for mobility and the need to reduce air pollution and to save energy. The classical planning process in public transport tries to achieve a reasonable compromise between service quality for passengers and operating costs. Service quality mostly considers quantities like average travel time and number of transfers. Since daily public transport inevitably suffers from delays caused by random disturbances and disruptions, robustness also plays a crucial role. While there are recent attempts to achieve delay-resistant timetables, comparably little work has been done to systematically assess and to compare the robustness of transport plans from a passenger point of view. We here provide a general and flexible framework for evaluating public transport plans (lines, timetables, and vehicle schedules) in various ways. It enables planners to explore several trade-offs between operating costs, service quality (average perceived travel time of passengers), and robustness against delays. For such an assessment we develop several passenger-oriented robustness tests which can be instantiated with parameterized delay scenarios. Important features of our framework include detailed passenger flow models, delay propagation schemes and disposition strategies, rerouting strategies as well as vehicle capacities. To demonstrate possible use cases, our framework has been applied to a variety of public transport plans which have been created for the same given demand for an artificial urban grid network and to instances for long-distance train networks. As one application we study the impact of different strategies to improve the robustness of timetables by insertion of supplement times. We also show that the framework can be used to optimize waiting strategies in delay management.

Cite as

Markus Friedrich, Matthias Müller-Hannemann, Ralf Rückert, Alexander Schiewe, and Anita Schöbel. Robustness as a Third Dimension for Evaluating Public Transport Plans. In 18th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2018). Open Access Series in Informatics (OASIcs), Volume 65, pp. 4:1-4:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


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@InProceedings{friedrich_et_al:OASIcs.ATMOS.2018.4,
  author =	{Friedrich, Markus and M\"{u}ller-Hannemann, Matthias and R\"{u}ckert, Ralf and Schiewe, Alexander and Sch\"{o}bel, Anita},
  title =	{{Robustness as a Third Dimension for Evaluating Public Transport Plans}},
  booktitle =	{18th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2018)},
  pages =	{4:1--4:17},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-096-5},
  ISSN =	{2190-6807},
  year =	{2018},
  volume =	{65},
  editor =	{Bornd\"{o}rfer, Ralf and Storandt, Sabine},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2018.4},
  URN =		{urn:nbn:de:0030-drops-97097},
  doi =		{10.4230/OASIcs.ATMOS.2018.4},
  annote =	{Keywords: robustness, timetabling, vehicle schedules, delays}
}
Document
Robustness Tests for Public Transport Planning

Authors: Markus Friedrich, Matthias Müller-Hannemann, Ralf Rückert, Alexander Schiewe, and Anita Schöbel

Published in: OASIcs, Volume 59, 17th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2017)


Abstract
The classical planning process in public transport planning focuses on the two criteria operating costs and quality for passengers. Quality mostly considers quantities like average travel time and number of transfers. Since public transport often suffers from delays caused by random disturbances, we are interested in adding a third dimension: robustness. We propose passenger-oriented robustness indicators for public transport networks and timetables. These robustness indicators are evaluated for several public transport plans which have been created for an artificial urban network with the same demand. The study shows that these indicators are suitable to measure the robustness of a line plan and a timetable. We explore different trade-offs between operating costs, quality (average travel time of passengers), and robustness against delays. Our results show that the proposed robustness indicators give reasonable results.

Cite as

Markus Friedrich, Matthias Müller-Hannemann, Ralf Rückert, Alexander Schiewe, and Anita Schöbel. Robustness Tests for Public Transport Planning. In 17th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2017). Open Access Series in Informatics (OASIcs), Volume 59, pp. 6:1-6:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)


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@InProceedings{friedrich_et_al:OASIcs.ATMOS.2017.6,
  author =	{Friedrich, Markus and M\"{u}ller-Hannemann, Matthias and R\"{u}ckert, Ralf and Schiewe, Alexander and Sch\"{o}bel, Anita},
  title =	{{Robustness Tests for Public Transport Planning}},
  booktitle =	{17th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2017)},
  pages =	{6:1--6:16},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-042-2},
  ISSN =	{2190-6807},
  year =	{2017},
  volume =	{59},
  editor =	{D'Angelo, Gianlorenzo and Dollevoet, Twan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2017.6},
  URN =		{urn:nbn:de:0030-drops-78904},
  doi =		{10.4230/OASIcs.ATMOS.2017.6},
  annote =	{Keywords: robustness measure, timetabling, line planning, delays, passenger-orientation}
}
Document
Sensitivity Analysis and Coupled Decisions in Passenger Flow-Based Train Dispatching

Authors: Martin Lemnian, Matthias Müller-Hannemann, and Ralf Rückert

Published in: OASIcs, Volume 54, 16th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2016)


Abstract
Frequent train delays make passenger-oriented train dispatching a task of high practical relevance. In case of delays, dispatchers have to decide whether trains should wait for one or several delayed feeder trains or should depart on time. To support dispatchers, we have recently introduced the train dispatching framework PANDA (CASPT 2015). In this paper, we present and evaluate two enhancements which are also of general interest. First, we study the sensitivity of waiting decisions with respect to the accuracy of passenger flow data. More specifically, we develop an integer linear programming formulation for the following optimization problem: Given a critical transfer, what is the minimum number of passengers we have to add or to subtract from the given passenger flow such that the decision would change from waiting to non-waiting or vice versa? Based on experiments with realistic passenger flows and delay data from 2015 in Germany, an important empirical finding is that a significant fraction of all decisions is highly sensitive to small changes in passenger flow composition. Hence, very accurate passenger flows are needed in these cases. Second, we investigate the practical value of more sophisticated simulations. A simple strategy evaluates the effect of a waiting decision of some critical transfer on passenger delay subject to the assumption that all subsequent decisions are taken according to standard waiting time rules, as usually employed by railway companies like Deutsche Bahn. Here we analyze the impact of a higher level of simulation where waiting decisions for a critical transfer are considered jointly with one or more other decisions for subsequent transfers. We learn that such "coupled decisions" lead to improved solution in about 6.3% of all considered cases.

Cite as

Martin Lemnian, Matthias Müller-Hannemann, and Ralf Rückert. Sensitivity Analysis and Coupled Decisions in Passenger Flow-Based Train Dispatching. In 16th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2016). Open Access Series in Informatics (OASIcs), Volume 54, pp. 2:1-2:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)


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@InProceedings{lemnian_et_al:OASIcs.ATMOS.2016.2,
  author =	{Lemnian, Martin and M\"{u}ller-Hannemann, Matthias and R\"{u}ckert, Ralf},
  title =	{{Sensitivity Analysis and Coupled Decisions in Passenger Flow-Based Train Dispatching}},
  booktitle =	{16th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2016)},
  pages =	{2:1--2:15},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-021-7},
  ISSN =	{2190-6807},
  year =	{2016},
  volume =	{54},
  editor =	{Goerigk, Marc and Werneck, Renato F.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2016.2},
  URN =		{urn:nbn:de:0030-drops-65264},
  doi =		{10.4230/OASIcs.ATMOS.2016.2},
  annote =	{Keywords: train delays, event-activity model, multi-criteria decisions, passenger flows, sensitivity analysis}
}
Document
Timing of Train Disposition: Towards Early Passenger Rerouting in Case of Delays

Authors: Martin Lemnian, Ralf Rückert, Steffen Rechner, Christoph Blendinger, and Matthias Müller-Hannemann

Published in: OASIcs, Volume 42, 14th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2014)


Abstract
Passenger-friendly train disposition is a challenging, highly complex online optimization problem with uncertain and incomplete information about future delays. In this paper we focus on the timing within the disposition process. We introduce three different classification schemes to predict as early as possible the status of a transfer: whether it will almost surely break, is so critically delayed that it requires manual disposition, or can be regarded as only slightly uncertain or as being safe. The three approaches use lower bounds on travel times, historical distributions of delay data, and fuzzy logic, respectively. In experiments with real delay data we achieve an excellent classification rate. Furthermore, using realistic passenger flows we observe that there is a significant potential to reduce the passenger delay if an early rerouting strategy is applied.

Cite as

Martin Lemnian, Ralf Rückert, Steffen Rechner, Christoph Blendinger, and Matthias Müller-Hannemann. Timing of Train Disposition: Towards Early Passenger Rerouting in Case of Delays. In 14th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 42, pp. 122-137, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2014)


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@InProceedings{lemnian_et_al:OASIcs.ATMOS.2014.122,
  author =	{Lemnian, Martin and R\"{u}ckert, Ralf and Rechner, Steffen and Blendinger, Christoph and M\"{u}ller-Hannemann, Matthias},
  title =	{{Timing of Train Disposition: Towards Early Passenger Rerouting in Case of Delays}},
  booktitle =	{14th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  pages =	{122--137},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-75-0},
  ISSN =	{2190-6807},
  year =	{2014},
  volume =	{42},
  editor =	{Funke, Stefan and Mihal\'{a}k, Mat\'{u}s},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2014.122},
  URN =		{urn:nbn:de:0030-drops-47576},
  doi =		{10.4230/OASIcs.ATMOS.2014.122},
  annote =	{Keywords: train delays, event-activity model, timing of decisions, passenger flows, passenger rerouting}
}
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