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Network Design Problem Considering Unsignalized Intersection Delay Function
, M.Sc. Thesis Sharif University of Technology ; Zokaie Aashtiani, Hedayat (Supervisor)
Abstract
In a discrete network design problem (DNDP), an optimal set of projects is chosen from suggested projects to expand a transportation network. The optimal set is selected by minimizing the total travel time with respect to the budget constraint. This problem is formulated as a bi-level optimization. In the current study, traffic assignment is solved at the lower level as a user equilibrium problem by considering the delay of intersections which is the major portion of total intra-city travel time. This study investigates the performance of the transportation network with more realistic assumptions compared to the previous studies in the network design problem.This study uses the branch and...
Effect of Using Multi-Variable Delay Functions for Unsignalized Intersections on Traffic Assignment Problem
, M.Sc. Thesis Sharif University of Technology ; Zakaei Ashtiani, Hedayat (Supervisor)
Abstract
A large amount of travel time in urban travels, is caused by intersection delays. Considering the intersection delay in traffic assignment, leads to more accurate network travel time and equilibrium flow pattern. Most traffic assignment softwares, consider unsignalized intersection delay as a constant or as a function of traffic volume on entering link, however, unsignalized intersection delay is a function of traffic volumes on all entering links. One of the reasons for these functions rarely being used in traffic assignments is that there is a lack of multi-variable delay function in transportation literature, and that most traffic assignment algorithms can not consider these functions....
Wardrop's first principle: Extension for capacitated networks
, Article Scientia Iranica ; Volume 28, Issue 1 , 2021 , Pages 175-191 ; 10263098 (ISSN) ; Poorzahedy, H ; Nourinejad, M ; Sharif University of Technology
Sharif University of Technology
2021
Abstract
In transportation literature, User Equilibrium (UE) has been widely studied since early 1950's, many studies of which define equilibrium flow of traffic for uncapacitated networks based on Wardrop's first principle, implying also a Nash Equilibrium (NE). Although, in general, the two equilibria (UE and NE) are not explicitly the same, they are shown to be equivalent under special conditions for uncapacitated UE, when volume delay functions are separable, continuous, non-decreasing and non-negative. A good deal of research is devoted to explain UE in capacitated networks based on Wardrop's first principle and the concept of generalized costs. However, UE for capacitated networks, even under...
Wardrop's first principle: Extension for capacitated networks
, Article Scientia Iranica ; Volume 28, Issue 1 , 2021 , Pages 175-191 ; 10263098 (ISSN) ; Poorzahedy, H ; Nourinejad, M ; Sharif University of Technology
Sharif University of Technology
2021
Abstract
In transportation literature, User Equilibrium (UE) has been widely studied since early 1950's, many studies of which define equilibrium flow of traffic for uncapacitated networks based on Wardrop's first principle, implying also a Nash Equilibrium (NE). Although, in general, the two equilibria (UE and NE) are not explicitly the same, they are shown to be equivalent under special conditions for uncapacitated UE, when volume delay functions are separable, continuous, non-decreasing and non-negative. A good deal of research is devoted to explain UE in capacitated networks based on Wardrop's first principle and the concept of generalized costs. However, UE for capacitated networks, even under...
Impact of Cognition and Cooperation on MAC Layer Performance Metrics
, M.Sc. Thesis Sharif University of Technology ; Ashtiani, Farid (Supervisor) ; Nasiri-Kenari, Masoumeh (Supervisor)
Abstract
In this thesis, we study the effect of cognition and cooperation on two important MAC layer performance metrics, i.e. maximum stable throughput and delay. To this end, we consider a broadband secondary user which interferes with N narrowband primary users. In our study we focus on four transmission protocols as well as two transmission policies, i.e. parallel and non-parallel transmissions. In the cooperative protocols, the broadband transmitter relays the packets of the primary users which have not correctly decoded at the primary receiver. In non-parallel transmission case, the packets of the broadband user are transmitted in the total available bandwidth and in parallel transmission case,...
Stochastic restricted broadcast process theory
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) ; Volume 6977 LNCS , 2011 , Pages 72-86 ; 03029743 (ISSN) ; 9783642247484 (ISBN) ; Talebi, M ; Movaghar, A ; Fokkink, W ; Sharif University of Technology
Abstract
We provide a framework for modeling and analyzing both qualitative and quantitative aspects of mobile ad hoc network (MANET) protocols above the data-link layer. We extend Restricted Broadcast Process Theory [11,9]: delay functions are assigned to actions, while the semantics captures the interplay of a MANET protocol with stochastic behavior of the data-link and physical layer, and the dynamic topology. A continuous-time Markov chain is derived from our semantic model by resolving non-determinism, using the notion of weak Markovian network bisimilarity. The framework is applied to a leader election algorithm
A theoretical multi-reflection method for analysis of optomechanical behavior of the Fabry-Perot cavity with moving boundary condition
, Article Optics Communications ; Volume 284, Issue 19 , 2011 , Pages 4789-4794 ; 00304018 (ISSN) ; Vahedi, M ; Abdi, M ; Ghobadi, R ; Golshani, M ; Tofighi, S ; Parvin, B ; Sharif University of Technology
Abstract
The opto-mechanical coupling and the generation of Stokes and anti-Stokes frequencies in the in-band and intra-band regimes of operation of the Fabry-Perot cavity with a moving mirror on the basis of multi-reflection method (MRM) are described by a unique theory. The frequency characteristic function of the Fabry-Perot filter is modified. By increasing the amplitude of mirror oscillation the Fabry-Perot bandwidth increases and normal mode splitting occurred. The conversion efficiencies of the Stokes and anti-Stokes frequencies versus the mechanical amplitude of oscillation have an optimum value. Also, the delay function corresponding to the radiation pressure is obtained