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    Vehicle identification sensors location problem for large networks

    , Article Journal of Intelligent Transportation Systems: Technology, Planning, and Operations ; 2018 ; 15472450 (ISSN) Hadavi, M ; Shafahi, Y ; Sharif University of Technology
    Taylor and Francis Inc  2018
    Abstract
    Finding the optimal location for sensors is a key problem in flow estimation. There are several location models that have been developed recently for vehicle identification (ID) sensors. However, these location models cannot be applied to large networks because there are many constraints and integer variables. Based on a property of the location problem for vehicle ID sensors, given the initial vehicle ID sensors that are pre-installed and fixed on the network, this article presents a solution that greatly reduces the size of this location problem. An applied example demonstrates that when 8% of the arcs from a real network that are randomly selected have a vehicle ID sensor, the reductions... 

    Vehicle identification sensors location problem for large networks

    , Article Journal of Intelligent Transportation Systems: Technology, Planning, and Operations ; Volume 23, Issue 4 , 2019 , Pages 389-402 ; 15472450 (ISSN) Hadavi, M ; Shafahi, Y ; Sharif University of Technology
    Taylor and Francis Inc  2019
    Abstract
    Finding the optimal location for sensors is a key problem in flow estimation. There are several location models that have been developed recently for vehicle identification (ID) sensors. However, these location models cannot be applied to large networks because there are many constraints and integer variables. Based on a property of the location problem for vehicle ID sensors, given the initial vehicle ID sensors that are pre-installed and fixed on the network, this article presents a solution that greatly reduces the size of this location problem. An applied example demonstrates that when 8% of the arcs from a real network that are randomly selected have a vehicle ID sensor, the reductions... 

    O-D Demand Estimation Based On Automatic Vehicle Identification Data

    , M.Sc. Thesis Sharif University of Technology Jamali, Amir (Author) ; Shafahi, Yusef (Supervisor)
    Abstract
    Regardless of the traffic model and its application, an essential input of transportation models is the amount of demand which is usually described using Origin-Destination (O-D) matrix. Many reaserchers have developed different O-D matrix estimation methods using traffic counts, which allow simple data collection as opposed to the costly traditional direct estimation methods based on home and roadside interview. However, Link data is not sufficient to obtain an unique answer. This reaserch tries to estimate O-D matrix by using Automated Vehicle Identification(AVI) data. The research formulates the problem of the estimating O-D matrix as a bi-level problem. The upper level consists of... 

    Vehicle identification sensor models for origin-destination estimation

    , Article Transportation Research Part B: Methodological ; Volume 89 , 2016 , Pages 82-106 ; 01912615 (ISSN) Hadavi, M ; Shafahi, Y ; Sharif University of Technology
    Elsevier Ltd 
    Abstract
    The traditional approach to origin-destination (OD) estimation based on data surveys is highly expensive. Therefore, researchers have attempted to develop reasonable low-cost approaches to estimating the OD vector, such as OD estimation based on traffic sensor data. In this estimation approach, the location problem for the sensors is critical. One type of sensor that can be used for this purpose, on which this paper focuses, is vehicle identification sensors. The information collected by these sensors that can be employed for OD estimation is discussed in this paper. We use data gathered by vehicle identification sensors that include an ID for each vehicle and the time at which the sensor... 

    Estimation of origin–destination matrices using link counts and partial path data

    , Article Transportation ; Volume 47, Issue 6 , 2020 , Pages 2923-2950 Rostami Nasab, M ; Shafahi, Y ; Sharif University of Technology
    Springer  2020
    Abstract
    After several decades of work by several talented researchers, estimation of the origin–destination matrix using traffic data has remained very challenging. This paper presents a set of innovative methods for estimation of the origin–destination matrix of large-scale networks, using vehicle counts on links, partial path data obtained from an automated vehicle identification system, and combinations of both data. These innovative methods are used to solve three origin–destination matrix estimation models. The first model is an extension of Spiess’s model which uses vehicle count data while the second model is an extension of Jamali’s model and it uses partial path data. The third model is a... 

    Solving Location Problem for Vehicle Identification Sensors to Observe or Estimate Path Flows in Larg-Scale Networks

    , M.Sc. Thesis Sharif University of Technology Talebian Yazdi, Pegah (Author) ; Shafahi, Yousef (Supervisor)
    Abstract
    Origin-Destination (OD) demand is one of the important requirements in transportation planning. Estimating OD demand could be an expensive and time consuming procedure. These days using vehicle identification sensors for OD estimation has become very common because of its low cost and high accuracy. In this study, we focus on solving location problems of these sensors with the aim of observe and estimate path flows. These problems have only been solved for small-scale networks until recently due to being computationally expensive. These years two basic models have been introduced : one, without considering time of vehicle ID detection and one, with considering that information. In this... 

    Vehicle Identification Sensors Location Problem with the Purpose of Origin-destination Estimation

    , Ph.D. Dissertation Sharif University of Technology Hadavi, Majid (Author) ; Shafahi, Yousef (Supervisor)
    Abstract
    Origin-Destination (OD) table is an important input for managing and controling processes of transportation systems. OD flow estimation based on the observations of traffic sensors is a famous way of attaining this table. Technology developments in recent years reduce the cost and improve the quality of the results for this method. This research explores the methods for applying one of these technologies, vehicle identification systems, with the purpose of OD flow estimation.In this research several location models for vehicle identification systems are presented. These models have better performances comparing to the existing models in the literature. Furthermore, location models for some... 

    Adjust of Origin-destination Matrices Using Link Counts and Partial Paths Data

    , M.Sc. Thesis Sharif University of Technology Rostami Nasab, Mojtaba (Author) ; Shafahi, Yousef (Supervisor)
    Abstract
    This paper presents five origin-destination (OD) flow estimation models using traffic sensors. The first model uses counting sensors data, the second model uses automated vehicle identification (AVI) sensors data and the third, fourth and fifth use combined data of counter and AVI sensors simultaneously. The first to fourth models are bi-level problems that the upper-level minimizes some objective functions where is the distance between estimated flows and observed flows. On the other hand, the lower-level problem finds user equilibrium (UE) flows pattern for estimated origin-destination matrix (ODM). The fifth model is a multi-objective problem, where a bi-level problem is solved for each... 

    Accurate detection and recognition of dirty vehicle plate numbers for high-speed applications

    , Article IEEE Transactions on Intelligent Transportation Systems ; Volume 18, Issue 4 , 2017 , Pages 767-779 ; 15249050 (ISSN) Panahi, R ; Gholampour, I ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Abstract
    This paper presents an online highly accurate system for automatic number plate recognition (ANPR) that can be used as a basis for many real-world ITS applications. The system is designed to deal with unclear vehicle plates, variations in weather and lighting conditions, different traffic situations, and high-speed vehicles. This paper addresses various issues by presenting proper hardware platforms along with real-Time, robust, and innovative algorithms. We have collected huge and highly inclusive data sets of Persian license plates for evaluations, comparisons, and improvement of various involved algorithms. The data sets include images that were captured from crossroads, streets, and... 

    Real-Time scale-invariant license plate detection using cascade classifiers

    , Article 2nd International Conference on Multimedia Information Processing and Retrieval, MIPR 2019, 28 March 2019 through 30 March 2019 ; Pages 399-402 , 2019 ; 9781728111988 (ISBN) Yousefi, E ; Nazem Deligani, A. H ; Jafari Amirbandi, J ; Karimzadeh Kiskani, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    This paper presents an online scale-invariant license plate detection (LPD) system with high accuracy for the automatic license plate recognition (ALPR) systems. A dataset of Persian plates is accumulated with more than 44,000 images of plates and 9000 frames of real world roads. For the plate detection and localization, a multi-stage classifier is trained with local binary pattern (LBP) features and a multi-scale algorithm to detect plates with any size within a frame. Besides, we proposed multiple algorithms to boost the performance and accuracy of our solution, including two-stage detection, background subtraction for non-moving areas elimination, and a sophisticated method for estimating...