Browsing by Author "Chronopoulos, Anthony"

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    Development of Advanced Traffic Flow Models and Implementation in Parallel Processing: Final Report
    (1992-10) Lyrintzis, Anastasios; Michalopoulos, Panos; Chronopoulos, Anthony
    Advanced traffic management and control schemes require that traffic simulation models be adequately accurate and computationally efficient in describing traffic flow dynamics. It is proved by practice that the continuum models are more suitable for such purposes. The KRONOS model, developed at the University of Minnesota for traffic flow simulations, is based on a simple continuum formulation implemented by a finite difference method. The results show that the program can be used for transportation planning, design, maintenance operations and freeway management. The main purpose of this project, funded by the Center for Transportation Studies of the University of Minnesota, is to reduce the above flaws by developing advanced traffic flow models. Moreover, various numerical methods are investigated in this project.
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    Parallel Traffic Flow Simulation of Freeway Networks, Phase 1: Final Report
    (1994-03) Chronopoulos, Anthony; Rhee, Choong-Yul; Wang, Gang
    Numerical methods for solving simple macroscopic traffic flow continuum models have been studied and efficiently implemented in traffic simulation codes. The Lax method is an explicit method which has been implemented to solve simple continuum model in the traffic simulation package KRONOS. In this part of the project we studied the implementation of the Lax method for solving a high-order flow conservation traffic model on Parallel Computers. We wrote an experimental code in C to simulate a freeway traffic flow. Tests with real data collected from the 1-35 W freeway in Minneapolis were conducted on a workstation computer. We then implemented the high order Lax method on a parallel machine and run tests with real data collected from an 18-mile stretch of the 1-494 freeway. The parallel implementation demonstrated significant execution time speedup.
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    Parallel Traffic Flow Simulation of Freeway Networks: Phase 2
    (Center for Transportation Studies, University of Minnesota, 1997-07) Chronopoulos, Anthony
    Explicit and implicit numerical methods for solving simple macroscopic traffic flow continuum models have been studied and efficiently implemented in traffic simulation codes in the past. We have already studied and implemented explicit methods for solving the high-order flow conservation traffic model. Implicit methods allow much larger time step size than explicit methods, for the same accuracy. However, at each time step a nonlinear system must be solved. We use the Newton method coupled with a linear iterative method (Orthomin). We accelerate the convergence of Orthomin with parallel incomplete LU factorization preconditionings. We implemented this implicit method on a 16 processor nCUBE2 parallel computer and obtained significant execution time speedup.