scholarly journals Simulation-Based Dynamic Passenger Flow Assignment Modelling for a Schedule-Based Transit Network

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Xiangming Yao ◽  
Baomin Han ◽  
Dandan Yu ◽  
Hui Ren
Keyword(s):  
Network Flow ◽  
Large Scale ◽  
Dynamic Traffic Assignment ◽  
Dynamic Network ◽  
Complete Information ◽  
Route Selection ◽  
Transit Networks ◽  
Simulation Based ◽  
Flow Equilibrium ◽  
Passenger Assignment

The online operation management and the offline policy evaluation in complex transit networks require an effective dynamic traffic assignment (DTA) method that can capture the temporal-spatial nature of traffic flows. The objective of this work is to propose a simulation-based dynamic passenger assignment framework and models for such applications in the context of schedule-based rail transit systems. In the simulation framework, travellers are regarded as individual agents who are able to obtain complete information on the current traffic conditions. A combined route selection model integrated with pretrip route selection and entrip route switch is established for achieving the dynamic network flow equilibrium status. The train agent is operated strictly with the timetable and its capacity limitation is considered. A continuous time-driven simulator based on the proposed framework and models is developed, whose performance is illustrated through a large-scale network of Beijing subway. The results indicate that more than 0.8 million individual passengers and thousands of trains can be simulated simultaneously at a speed ten times faster than real time. This study provides an efficient approach to analyze the dynamic demand-supply relationship for large schedule-based transit networks.

scholarly journals Computational Methods for Calculating Multimodal Multiclass Traffic Network Equilibrium: Simulation Benchmark on a Large-Scale Test Case

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Mostafa Ameli ◽  
Jean-Patrick Lebacque ◽  
Ludovic Leclercq
Keyword(s):  
Computational Methods ◽  
Large Scale ◽  
Dynamic Traffic Assignment ◽  
Dynamic Network ◽  
Computation Time ◽  
Test Case ◽  
Network Equilibrium ◽  
Loading Mode ◽  
Network Loading ◽  
Metaheuristic Methods

This study reviews existing computational methods to calculate simulation-based dynamic network equilibrium. We consider a trip-based multimodal approach for the dynamic network loading. Mode and path choices are carried out at the same level; therefore, travel times depend on the travel path and the mode attributes of travelers. This study develops a multiclass model with several parameters per class. Two different categories of algorithms (heuristic and metaheuristic) are considered in order to solve the discrete dynamic traffic assignment (DTA) problem. Finally, we analyze the equilibrium in a large-scale multimodal DTA test case (Lyon 6th + Villeurbanne) in order to investigate the performance of different optimization approaches to solve trip-based DTA. The results show that, in a multimodal and heterogeneous setting, the metaheuristic methods provide better solutions than the heuristic methods in terms of optimality and computation time. These improvements are even more significant than in a homogeneous setting.

scholarly journals Bayesian dynamic modeling and monitoring of network flows

2019 ◽  
Vol 7 (3) ◽  
pp. 292-318 ◽  
Author(s):  
Xi Chen ◽  
David Banks ◽  
Mike West
Keyword(s):  
Time Series ◽  
Dynamic Modeling ◽  
Network Flow ◽  
Large Scale ◽  
Sequential Analysis ◽  
Linear Models ◽  
Network Flows ◽  
Dynamic Network ◽  
Dynamic Network Flow ◽  
Large Scale Networks

AbstractIn the context of a motivating study of dynamic network flow data on a large-scale e-commerce website, we develop Bayesian models for online/sequential analysis for monitoring and adapting to changes reflected in node–node traffic. For large-scale networks, we customize core Bayesian time series analysis methods using dynamic generalized linear models (DGLMs). These are integrated into the context of multivariate networks using the concept of decouple/recouple that was recently introduced in multivariate time series. This method enables flexible dynamic modeling of flows on large-scale networks and exploitation of partial parallelization of analysis while maintaining coherence with an over-arching multivariate dynamic flow model. This approach is anchored in a case study on Internet data, with flows of visitors to a commercial news website defining a long time series of node–node counts on over 56,000 node pairs. Central questions include characterizing inherent stochasticity in traffic patterns, understanding node–node interactions, adapting to dynamic changes in flows and allowing for sensitive monitoring to flag anomalies. The methodology of dynamic network DGLMs applies to many dynamic network flow studies.

scholarly journals A Simulation-Based Approximation Algorithm for Dynamic Marginal Cost Pricing

2010 ◽  
Vol 47 (4) ◽  
Author(s):  
Ampol Karoonsoontawong ◽  
Satish Ukkusuri ◽  
S. Travis Waller ◽  
Kara M. Kockelman
Keyword(s):  
Approximation Algorithm ◽  
Marginal Cost ◽  
Large Scale ◽  
Dynamic Traffic Assignment ◽  
User Equilibrium ◽  
Marginal Costs ◽  
Marginal Cost Pricing ◽  
Simulation Based ◽  
The Status ◽  
Inner Approximation

This work offers a simulation-based approximation algorithm for dynamic marginal cost pricing (MCP) congestion pricing that is a direct extension of its static counterpart. The algorithm approximates the time-dependent marginal costs, and is incorporated into the inner approximation dynamic user equilibrium algorithm to evaluate the results of dynamic MCP, which are then compared to static assignment results with MCP from previous study. The status quo and dynamic MCP-on-freeways scenarios are simulated (and then compared) on the Dallas-Fort Worth 35,732-link network. Due to computational requirements for such a large-scale dynamic traffic assignment application, the dynamic MCP scenario is simulated without feedback, and only route choices are permitted to vary. When prices are imposed on freeway users, some minor system benefits are observed, including a delay in the onset of congestion. Dynamic prices vary substantially over the three-hour period of analysis, reflecting changes in freeway congestion. Reasons for any inconsistencies between dynamic and static results are discussed, along with important enhancements to future implementation.

scholarly journals Adaptation of Random Binomial Graphs for Testing Network Flow Problems Algorithms

Mathematics ◽  
2021 ◽  
Vol 9 (15) ◽  
pp. 1716
Author(s):  
Adrian Marius Deaconu ◽  
Delia Spridon
Keyword(s):  
Network Flow ◽  
Large Scale ◽  
Random Network ◽  
Minimum Cost ◽  
Maximum Flow ◽  
Network Flow Problems ◽  
Commodity Flow ◽  
Vast Number ◽  
Flow Problems ◽  
Execution Speed

Algorithms for network flow problems, such as maximum flow, minimum cost flow, and multi-commodity flow problems, are continuously developed and improved, and so, random network generators become indispensable to simulate the functionality and to test the correctness and the execution speed of these algorithms. For this purpose, in this paper, the well-known Erdős–Rényi model is adapted to generate random flow (transportation) networks. The developed algorithm is fast and based on the natural property of the flow that can be decomposed into directed elementary s-t paths and cycles. So, the proposed algorithm can be used to quickly build a vast number of networks as well as large-scale networks especially designed for s-t flows.

scholarly journals PRISMS-Fatigue computational framework for fatigue analysis in polycrystalline metals and alloys

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Mohammadreza Yaghoobi ◽  
Krzysztof S. Stopka ◽  
Aaditya Lakshmanan ◽  
Veera Sundararaghavan ◽  
John E. Allison ◽  
...  
Keyword(s):  
Open Source ◽  
Open Source Software ◽  
Large Scale ◽  
Metals And Alloys ◽  
Analysis Tool ◽  
Computational Framework ◽  
Crystal Plasticity Finite Element ◽  
Polycrystalline Metals ◽  
Simulation Based ◽  
Open Source Framework

AbstractThe PRISMS-Fatigue open-source framework for simulation-based analysis of microstructural influences on fatigue resistance for polycrystalline metals and alloys is presented here. The framework uses the crystal plasticity finite element method as its microstructure analysis tool and provides a highly efficient, scalable, flexible, and easy-to-use ICME community platform. The PRISMS-Fatigue framework is linked to different open-source software to instantiate microstructures, compute the material response, and assess fatigue indicator parameters. The performance of PRISMS-Fatigue is benchmarked against a similar framework implemented using ABAQUS. Results indicate that the multilevel parallelism scheme of PRISMS-Fatigue is more efficient and scalable than ABAQUS for large-scale fatigue simulations. The performance and flexibility of this framework is demonstrated with various examples that assess the driving force for fatigue crack formation of microstructures with different crystallographic textures, grain morphologies, and grain numbers, and under different multiaxial strain states, strain magnitudes, and boundary conditions.

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