Loading...
Search for:
farjami--hedayat
0.116 seconds
Acceptance of Heavy-Automated Vehicles
, M.Sc. Thesis Sharif University of Technology ; Nassiri, Habibollah (Supervisor)
Abstract
Technology is changing the travel behavior of people around the world. Automated vehicles offer new solutions to some of the problems in transportation. This technology can improve traffic safety, land use development, traffic quality, and fuel consumption. Nevertheless, these solutions can be applied, only if Automated Vehicles are accepted and used by people. Due to a lack of mass production in the industry yet, automated vehicles’ adoption and market share are not yet determined and therefore certain to happen. This study surveyed 334 Iranian truck drivers in October 2019 to examine their opinions of heavy-automated vehicles (i.e. automated trucks), the factors and variables that affect...
Application of the homotopy method for analytical solution of non-Newtonian channel flows
, Article Physica Scripta ; Volume 79, Issue 6 , 2009 ; 00318949 (ISSN) ; Kharazmi, S ; Farjami, Y ; Sharif University of Technology
2009
Abstract
This paper presents the homotopy series solution of the Navier-Stokes and energy equations for non-Newtonian flows. Three different problems, Couette flow, Poiseuille flow and Couette-Poiseuille flow have been investigated. For all three cases, the nonlinear momentum and energy equations have been solved using the homotopy method and analytical approximations for the velocity and the temperature distribution have been obtained. The current results agree well with those obtained by the homotopy perturbation method derived by Siddiqui et al (2008 Chaos Solitons Fractals36 182-92). In addition to providing analytical solutions, this paper draws attention to interesting physical phenomena...
Application of the homotopy perturbation method to linear and nonlinear fourth-order boundary value problems
, Article Physica Scripta ; Volume 77, Issue 5 , 2008 ; 00318949 (ISSN) ; Rasi Marzabadi, F ; Farjami, Y ; Sharif University of Technology
2008
Abstract
In this study, we applied the homotopy perturbation (HP) method for solving linear and nonlinear fourth-order boundary value problems. The analytical results of the boundary value problems have been obtained in terms of a convergent series with easily computable components. Comparisons between the results of the HP method and the analytical solution showed that this method gives very precise results with a few terms. In the implied HP method, some unknown parameters in the initial guess are introduced, which are identified after applying boundary conditions. This improvement results in higher accuracy. © 2008 The Royal Swedish Academy of Sciences
Developing an adaptive fractional model of a magnetic structure using evolutionary algorithm
, Article ICCC 2008 - IEEE 6th International Conference on Computational Cybernetics, Stara Lesna, 27 November 2008 through 29 November 2008 ; 2008 , Pages 189-192 ; 9781424428755 (ISBN) ; Hajihasani, M ; Farjami, Y ; Norouzi, E ; Sharif University of Technology
2008
Abstract
Magnetic flux leakage technique is used extensively to detect and characterize defects in natural gas and oil transmission pipelines. The amount of magnetic flux introduced into the test sample is an important factor in the resolution of flaw detection. It depends on the power of permanent magnets and the geometrical design of the magnetic yoke. Finite element method (FEM) is the most widely used method of analyzing magnetic yoke due to its power, accuracy and straightforwardness. On the other hand its calculations are so complicated and time consuming, and every single modification in the parameters of the problem requires a new run. In this paper, we present an innovative method to...
Electrical Vehicles' Traffic Assignment Considering Recharging Time as Function of Amount of Charge
, M.Sc. Thesis Sharif University of Technology ; Aashtiani, Hedayat (Supervisor)
Abstract
Nonstop growth of environmental concerns regarding ordinary vehicles detrimental effects have led to increasing use of Electrical Vehicles which require more researches in different fields of study. The main purpose of this study is solving the problem of Electrical Vehicles' traffic assignment considering recharging time as a function of amount of charge. Existing EVs have limited driving range, and these cars' drivers usually have to spend a considerable amount of time on recharging in order to complete a path. As a result, their corresponding optimum route choice differs from that of gasoline-based vehicles' drivers. In more detail, this study proposes an algorithm to solve the shortest...
Approximate analytical solutions of an axially moving spacecraft appendage subjected to tip mass
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Vol. 228, issue. 9 , 2014 , pp. 1487-1497 ; ISSN: 09544100 ; Khayyat, A. A ; Farjami, Y ; Abedian, A ; Sharif University of Technology
2014
Abstract
Approximate solutions for vibrations of flexible beam-type appendages subjected to tip mass are studied while uniform and exponential profiles for arm deployment are simulated. Applying an equivalent dynamical system and following Lagrangian approach, the equations of motion of the system are derived as nonlinear ordinary differential equations (ODEs) (with time-varying coefficients), in which the effect of the tip mass can be considered as some nonlinearity added to the 'no tip mass' case dynamics. The approximate closed-form solutions are obtained through a novel methodology using a computer algorithm, in which the solutions of the 'no tip mass' case are expanded by imposing quadratic...
Routing and Schedueling for Hazardous Materials Shipment
,
M.Sc. Thesis
Sharif University of Technology
;
Zokaei Aashtiani, Hedayat
(Supervisor)
Abstract
Shipment of hazardous materials has got an important role in the world of today. Nowadays, sustainable development has got serious attention, and human health and environment are one of the sustainable development bases. The risk of hazardous materials for human health and environment, and also importance of this kind of materials in the industrial economy, make necessity of programming for shipment of hazardous materials more serious. This thesis, presents an optimiziation model for routing and scheduling for shipment of hazardous materials. This model is a multi criteria time varing mixed integer programming (MIP). The presented model, finds the optimal routs and scheduling of movement...
Solving Nonlinear Multicommodity Network Flow Problem by Penalty Function Methods
, M.Sc. Thesis Sharif University of Technology ; Zokaee Aashtiani, Hedayat (Supervisor)
Abstract
Multicommodity network flow problem arises in the areas of transportation, logistics, and, telecommunication. The cost of each arc might be a linear or nonlinear function of the sum of commodity flows on that arc. Most of researches have worked on linear multicommodity flow problem. In addition, they consider the shared capacity constraints as the side constraints. In this thesis, we present a penalty-based algorithm for solving the multicommodity network flow problem with a linear or nonlinear objective function and considering the shared capacity constraints as the side. To solve multicommodity network flow problem, we relax the shared capacity constraints, and add a penalty term for the...
Network Pricing Using Path Flow Information
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
The toll pricing problem has been investigated in the literature for the cases of link, cordon, and facility (bridge, tunnel and etc.) pricing. Taking advantages of new technologies, nowadays it is possible to track the path of individual vehicles and collect the tolls by means of electronic devices. In this regard, we concerned the problem of path pricing. In this thesis, a variety of models for path pricing is proposed, the models are solved for the Hearn network and the results are compared to the results of link pricing models. In addition to the models, one exact solution method and two heuristic methods are proposed for the model of path pricing with the minimum total toll....
Solving Traffic Assignment Problem with Side Constraints
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
In recent years, traffic assignment problem with side constraints has been considered because of the importance of transportation supply management. Side constraints which are appeared due to imposing the traffic control policies are usually represented in form of link, node or district capacity constraints. Although link capacity constraint has been extensively studied, only a few papers on the other types of constraints such as capacity constraint on inflow to a district of city exist in the literature. In this research a method based on dynamic penalty function (DPF) is presented to solve traffic assignment problem with side constraints. Solution algorithm has been coded in a programming...
Comparing Meta-Heuristic Algorithms for Solving Transportation Network Design Problem
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
Discrete network design problem is selecting a set of feasible projects among a set of candidate projects, considering a budget constraint in which user's cost is being minimized. Network design problem is one of the complicated problems in transportation science, since it is a bi-level problem in which the lower level is a traffic assignment problem and the upper level is finding the best set of arcs. Meta-heuristic algorithms can be used to solve this problem. Although, there is no guarantee to find the optimal solution by Meta-heuristic algorithms, but they find good solutions in short times. The purpose of this study is comparing the efficiency of three Meta-heuristic algorithms for...
A Comparison Between Path-based Traffic Assignment Algorithms
, M.Sc. Thesis Sharif University of Technology ; Zokaie Aashtiani, Hedayat (Supervisor)
Abstract
In the transportation litreture, many different algorithms have been proposed for solving traffic assignment problem based on the user-equilibrium principal.These algorithms are devided into two main groups: Path-based algorithms and arc-based algorithms. In the past, arc-based algorithms has attracted quite attention, but recent scientific progress in the computer science changed this viewpoint to the state of path-based algorithms. Much of the attention has been focused on three particular algorithms: the complementarity (C) algorithm, the gradient projection (GP) algorithm and the disaggregate simplicial decomposition (DSD) algorithm. In this thesis, these three algorithms have been...
Creating Bus Timetables with Maximum Synchronization
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
Improving synchronization in a bus network has a profound effect on reducung waiting times and increasing satisfaction of system’s users. By doing so, the scheduler create a more attractive transit system that generates the opportunity for increasing the number of riders. In this research, the problem of creating timetables with maximum synchronization is modeled as a mixed integer programing (MIP) problem. The objective of this model is to minimize the total waiting times of passengers at transfer nodes. For this purpose, the model take advantage of uneven headways. Some of features that distinguish this research are more realistic objective function, and considering adjacent departures...
A Heuristic Method for Coordination of Signalized Intersection
, M.Sc. Thesis Sharif University of Technology ; Zokaei Ashtiani, Hedayat (Supervisor)
Abstract
Signal coordination is one of the strategies to decrease the delay times in transportation networks. The application of dynamic traffic assignment has been made possible the modeling of flow loading in network links, and queue formation and dissipation in signalized intersections. In this thesis, signal offset set which produce the minimum total travel time in a network is determined, using a cell-based dynamic traffic assignment which is based on the cell transmission model. Genetic algorithm has been implemented to reach the suboptimal offset set. The application of the algorithm on a small test network shows that it can reach to an offset set with 1% error to the optimal offset set, by...
Stochastic Traffic Assignment Based on Discrete Choice Models
, M.Sc. Thesis Sharif University of Technology ; Zakaei Ashtiani, Hedayat (Supervisor)
Abstract
Accurate and realistic forecasts of traffic pattern in the networks can affect many decisions of urban transportation planning. In recent years, traffic assignment (TA) using stochastic models have received more attention by researchers of this field. Stochastic approach of route choice modeling using random utility theory has specifically developed to relax restrictive assumptions of traditional deterministic model and to address randomness nature of travelerʼs behavior. Together with development of discrete choice theory, more advanced models have been utilized to better represent route choice behavior. Although there have been considerable researches in the context of stochastic traffic...
Equilibrium Flow with Side Constraint
, M.Sc. Thesis Sharif University of Technology ; Zakai Aashtiani, Hedayat (Supervisor)
Abstract
Wardrop’s first principle for defining the equilibrium flow in transportation networks is one of the mostly accepted assumptions in traffic assignment models. Optimization Models, Variational Inequalities, and Complementarity Equations are among the known models based on this assumption. In these models with the assumption of unlimited capacity for the network’s arcs and use of nonlinear cost functions, the constraint of arc capacity is considered implicitly. Another approach is to consider the arc capacity, explicitly. In recent decade this approach was the subject of some researches. In this thesis, these researches will be discussed. Then, researches about explicit consideration of the...
Multi Modal Traffic Assignment with Mode Choice Models
, M.Sc. Thesis Sharif University of Technology ; Zakai Ashtiani, Hedayat (Supervisor)
Abstract
Traffic congestion is one of the most important issues facing modern societies that causes many impacts such as environmental pollutions and waste of physical and spiritual energies. One of the traffic congestion mitigation strategies is network management, which encompasses a diverse range of tools. Efficient management of urban transportation network requires the transportation network information. Traffic equilibrium in the transportation network is one of the fundamental information that is required for most of network management tools. In this study, a multi-modal traffic assignment model with complementarity structure is proposed that can determine the multi-modal traffic equilibrium...
Cordon Location and Congestion Pricing in Transportation Networks
, M.Sc. Thesis Sharif University of Technology ; Zakaei Ashtian, Hedayat (Supervisor)
Abstract
Cordon pricing is one of the methods for charging transportation network. In a cordon based pricing scheme, users who want to drive into the congested area of city and pass some special links which form the cordon, have to pay toll. The most important things in this method of pricing are finding the appropriate links which can shape the cordon and determining the tool level. This study, investigates an algorithm to find the optimal cordon location and toll level simultaneously in order to maximize social welfare. At first, assuming that cordon location is fixed and links that form the cordon are identified, a golden section method has been proposed for finding the optimal toll level. Then,...
Optimal Deployment of Electric Vehicle Charging Stations
, M.Sc. Thesis Sharif University of Technology ; Zakaei Ashtiani, Hedayat (Supervisor)
Abstract
Limited oil resources, increasing rate of oil consumption, and environmental concerns related to burning fossil fuels promote the use of alternative fuel vehicles. Electric vehicles are common among alternative fuel vehicles which decrease greenhouse gases emission and fossil fuel dependence. To increase electric vehicle market share, some challenges need to be overcome including range anxiety. Limited driving range is one of the main challenges for battery-powered electric vehicles. The distance limit inevitably changes electric vehicle drivers’ travel behavior. Given the scarcity of charging stations, consumers perceive this driving range limit to be a potential worry. Therefore,...
An Approach for Solving CordonPricing Problem with Two Classes of Vehicles
, M.Sc. Thesis Sharif University of Technology ; Zakaei Ashtiani, Hedayat (Supervisor)
Abstract
Nowadays the increasing congestion in transportation networks has made the managerial methods for controlling the congestion more important. Cordon pricing is one of the managerial means for reducing congestion. Therefore, accurate modeling methods that are consistent with reality and efficient traffic assignment algorithms play important roles in solving this problem. In this research several multiclass traffic assignment algorithms were examined and simultaneous complementarity algorithm was recognized to be able to yield equilibrium solution faster than other algorithms examined in this study. The aim of this thesis was also to analyze the effects of cordon pricing on networks with...
Nowadays the increasing congestion in transportation networks has made the managerial methods for controlling the congestion more important. Cordon pricing is one of the managerial means for reducing congestion. Therefore, accurate modeling methods that are consistent with reality and efficient traffic assignment algorithms play important roles in solving this problem. In this research several multiclass traffic assignment algorithms were examined and simultaneous complementarity algorithm was recognized to be able to yield equilibrium solution faster than other algorithms examined in this study. The aim of this thesis was also to analyze the effects of cordon pricing on networks with...