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    Short-Term Traffic Volume Estimation Based on Macroscopic Flow Characteristics

    , M.Sc. Thesis Sharif University of Technology Tajalli, Mehrdad (Author) ; Poorzahedy, Hossein (Supervisor)
    Abstract
    Traffic volume is the most important characteristic in most traffic studies, which is regularly measured by sampling methods for a given road. Traffic volume has determining effect in specifying network origin-destination demand, improvement of roads, traffic distributions over the network, improving road parameters, air pollution and in other aspects of flow in the network. There are many ways to measure traffic volume in different situations. However, most of them are expensive to implement and in cases which take a long time to do the survey, or the number of locations are excessive, the operation would not be cost-effective. In this research we investigate using macroscopic... 

    Analysis of Effective Parameters in Localization Accuracy of Positioning Systems

    , Ph.D. Dissertation Sharif University of Technology Sadeghi, Mohammad (Author) ; Behnia, Fereidoon (Supervisor)
    Abstract
    Target localization using positioning systems has long been considered by researchers in various fields.One of the important issues in localizing a target is the accuracy of its determined position. There are several parameters in the accuracy of position estimation. In a comprehensive view, these parameters can be divided into three general factors,including the relative geometry of the transmitters/receivers with respect to the target, the accuracy of measurements, and the type of target position estimator.The first factor, i.e. the relative geometry between the target and the transmit/receive antennas, plays an important role in localization accuracy. In the first part of this thesis, the... 

    A subsampling-predictor associated approach for fast global motion estimation

    , Article Scientia Iranica ; Volume 19, Issue 6 , December , 2012 , Pages 1746-1753 ; 10263098 (ISSN) Ahmadi, A ; Talebi, S ; Salehinejad, H ; Sharif University of Technology
    2012
    Abstract
    Global Motion Estimation (GME) has many important roles in numerous applications, such as video compression, image stabilization, video-object segmentation, and etc. One well-known GME method is the gradient-based technique. This method uses optimization techniques, like the Levenberg-Marquardt algorithm, to minimize estimation error. Such algorithms require an initial value for the initializing step. In this paper, we propose a simple and reliable GME structure with a new predictor. This structure uses a three-step search and a predictor for the initializing step. It is also incorporated with a fast GME method that uses pixel subsampling. This incorporation reduces the computational... 

    Joint edge detection and motion estimation of cardiac MR image sequence by a phase field method

    , Article Computers in Biology and Medicine ; Volume 40, Issue 1 , 2010 , Pages 21-28 ; 00104825 (ISSN) Eslami, A ; Jahed, M ; Preusser, T ; Sharif University of Technology
    Abstract
    In this paper a variational framework for joint segmentation and motion estimation is employed for inspecting heart in Cine MRI sequences. A functional including Mumford-Shah segmentation and optical flow based dense motion estimation is approximated using the phase-field technique. The minimizer of the functional provides an optimum motion field and edge set by considering both spatial and temporal discontinuities. Exploiting calculus of variation principles, multiple partial differential equations associated with the Euler-Lagrange equations of the functional are extracted, first. Next, the finite element method is used to discretize the resulting PDEs for numerical solution. Several... 

    New half-pixel accuracy motion estimation algorithms for low bitrate video communications

    , Article Scientia Iranica ; Volume 15, Issue 6 , 2008 , Pages 507-516 ; 10263098 (ISSN) Mahdavi Nasab, H ; Kasaei, S ; Sharif University of Technology
    Sharif University of Technology  2008
    Abstract
    Fractional-pixel accuracy Motion Estimation (ME) has been shown to result in higher quality reconstructed image sequences in hybrid video coding systems. However, the higher quality is achieved by notably increased Motion Field (MF) bitrate and more complex computations. In this paper, new half-pixel block matching ME algorithms are proposed to improve the rate-distortion characteristics of low bitrate video communications. The proposed methods tend to decrease the required video bandwidth, while improving the motion compensation quality. The key idea is to put a deeper focus on the search origin of the ME process, based on center-bias characteristics of low bitrate video MFs. To employ the...