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asef-vaziri--ardavan
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Guide Path Design for Automated Guided Vehicles
, Ph.D. Dissertation Sharif University of Technology ; Eshghi, Koorosh (Supervisor) ; Asef Vaziri, Ardavan ($item.subfieldsMap.e)
Abstract
Around 20 to 50 percent of the operation costs occurs in manufacturing is related to facility layout. Efficient design would reduce these costs by 10 to 30 percent. Facility layout consists of design of material handling system and plant layout. Design of material handling system includes determining, the flow network and locations of Pick-up and Delivery stations which are defined regarding to the kind of material handling equipment. Today, Automated Guided Vehicles are considered as the basic material handling equipment due to their potentials in production planning and controls, high safety and flexibility and low expenses.
In this thesis, we first discuss the design of the shortest...
In this thesis, we first discuss the design of the shortest...
Loop-based facility layout design under flexible bay structures
, Article International Journal of Production Economics ; Volume 193 , 2017 , Pages 713-725 ; 09255273 (ISSN) ; Jahandideh, H ; Modarres, M ; Sharif University of Technology
2017
Abstract
We develop heuristic procedures for concurrent design of block layout, material flow network, and input and output stations. Unlike the common practice in the flexible bay structure layout design, our objective function includes both loaded and empty flow between pairs of I/O stations. This measure of effectiveness is the main determinant of the fleet size of the vehicles, which in turn is the major driver of the total investment and operational costs in vehicle-based material handling. Our work is the first to design flexible bay structure layouts for loop-based material flow patterns. We first develop heuristic algorithms to configure the layout on the foundations of a unidirectional loop...
An ant colony system for enhanced loop-based aisle-network design
, Article European Journal of Operational Research ; Volume 207, Issue 1 , 2010 , Pages 110-120 ; 03772217 (ISSN) ; Kazemi, M ; Eshghi, K ; Lahmar, M ; Sharif University of Technology
2010
Abstract
The purpose of this paper is to develop a global optimization model, simplification schemes, and a heuristic procedure for the design of a shortcut-enhanced unidirectional loop aisle-network with pick-up and drop-off stations. The objective is to minimize the total loaded and empty trip distances. This objective is the main determinant for the fleet size of the vehicles, which in turn is the driver of the total life-cycle cost of vehicle-based unit-load transport systems. The shortcut considerably reduces the length of the trips while maintaining the simplicity of the system. The global model solves simultaneously for the loop design, stations' locations and shortcut design. We then develop...
A comparative appraisal of roadway accident for Asia-Pacific countries
, Article International Journal of Engineering, Transactions A: Basics ; Volume 23, Issue 2 , 2010 , Pages 111-126 ; 17281431 (ISSN) ; Sharif University of Technology
Materials and Energy Research Center
2010
Abstract
This paper describes an attempt to shed some light on road safety in Asia Pacific region by characterizing and assessing its road accidents. The relevant national road accident data were extracted from centralized data sources of international agencies. Due to data incompleteness and missing values, 21 Asia Pacific countries, presenting more than half of the world's population, were selected for detailed analysis. The study database consisted of 7 variables, covering years 1980 and 1995. The univariate and multivariate statistical analyses for the selected countries showed interesting results and relations for the selected variables. Accident rates, reflecting road accident risk and...
A study of highway noise pollution in Tehran
, Article Eighth International Conference on Urban Transport and the Environment for the 21st Century, URBAN TRANSPORT VIII, Seville, 13 March 2002 through 15 March 2002 ; 2002 , Pages 651-657 ; 1462608X (ISSN) ; Sharif University of Technology
2002
Abstract
Roadway traffic noise pollution for the Greater Tehran Metropolitan Area (GTMA) was analyzed. The study database consisted of relevant information about the noise level, traffic, roadway and meteorological characteristics. The collected noise level information at the roadway sound level meter receptor site included equivalent noise level. The equivalent noise level at reception points along the GTMA roadways was found often in breach of noise standards
Development of highway congestion index with fuzzy set models
, Article Transportation Research Record ; Issue 1802 , 2002 , Pages 16-22 ; 03611981 (ISSN) ; Sharif University of Technology
National Research Council
2002
Abstract
Development of a highway congestion index on the basis of expert and user opinions with fuzzy set theory was attempted. Forty 1-min videotape segments showing different highway traffic flow conditions were displayed to a group of highway experts and users. They were asked to complete the relevant questionnaires on the existence and acceptability of congestion for each video segment display. Five congestion-descriptive variables of travel speed, travel rate, delay rate, travel rate ratio, and delay ratio were determined for each video segment. Information about the values of congestion-descriptive variables for the displayed videos, questionnaire responses, and fuzzy set theory were used to...
Modeling vehicle air pollution attributes by artificial neural network
, Article Scientia Iranica ; Volume 8, Issue 1 , 2001 , Pages 10-15 ; 10263098 (ISSN) ; Sharif University of Technology
Sharif University of Technology
2001
Abstract
The municipalities of large Iranian cities require regular air pollutant emission monitoring for motor vehicles. The recorded data include information about commonly regulated air pollutants and motor vehicle characteristics which were randomly selected and studied from the Tehran database. Regression analysis was found ineffective in modeling the relationships among air pollutant, meteorological and motor vehicle characteristics. However, the artificial neural network, ANN, modeling seem to be a useful tool for prediction of air pollutants. The developed ANN models were found to be superior to the developed regression models. Application of the study approach and results could improve motor...
Use of the Bayesian Approach in Failure Analysis and Life Prediction of Coil Springs of a Suspension System
, M.Sc. Thesis Sharif University of Technology ; Adib Nazari, Saeed (Supervisor) ; Karimzadeh, Ardavan (Supervisor)
Abstract
In this thesis, bayesian network has been used in analyzing the failure of a structural component. The design life of a structural component of a system can be limited or unlimited depending on the working conditions considered by the designers. However, usually during the operation of an industrial system or device, a structural component of it fails prematurely, in other words, its actual life is less than the design life. In this case, the failure must be analyzed to find the causes and factors. The method of work is such that first, according to the problem and the type of failure, the required analyzes and studies are considered. Then, a number of samples of the components, whose...
Experimental Investigation, Failure Analysis and Life Extension of Engine Cylinder Liners
, M.Sc. Thesis Sharif University of Technology ; Adib Nazari, Saeed (Supervisor) ; Karimzadeh, Ardavan (Supervisor)
Abstract
A Cylinder Liner is one of the most important functional parts that gives a wear protective surface of cylinder block for piston and piston rings. Liners are used in automotive, ships, power aircrafts, and power generation units and the most load carrying part in internal combustion engine. Liners are subjected to various stresses during the engine working status. The stresses which act on cylinder liner are stress due to action of gas pressure and heat. Result of that stresses, wear developed inside of liner and internal or external cracking of cylinder liner takes place. In this paper, complete thermo-mechanical analysis of cylinder liner and failure mechanisms detected in alloyed cast...
Rolling Contact Mechanics of Graded Coatings Involving Frictional Heating
, Ph.D. Dissertation Sharif University of Technology ; Adibnazari, Saeed (Supervisor) ; Karimzadeh, Ardavan (Co-Supervisor)
Abstract
In this Thesis ,the two-dimensional thermoelastic tractive rolling contact problem for an FGM coated half-plane under the plane strain deformation is investigated. A rigid cylinder rolls on the surface of an FGM coated half-plane with constant translational velocity, generating frictional heat in the slip zones of the contact area. Thermo-mechanical properties of the FGM vary exponentially along the thickness. It is assumed that the contact area consists of a central stick zone and two slip zones of the same sign. The transfer matrix method and Fourier integral transform technique are used to achieve a system of two Cauchy singular integral equations. The associated governing equations are...
Evaluating Effect of Major Approach Median on Minor Approach Drivers’ Behavior at Major-Minor Intersections With Stop Control
, M.Sc. Thesis Sharif University of Technology ; Vaziri, Manouchehr (Supervisor)
Abstract
At major-minor intersections with no timing and signal control, with comparison to those with signal control, a lower level of control is imposed on intersection’s traffic. So the driver’s behavior has more effective and important role on geometric and traffic design of intersection. Therefore, recognizing drivers’ behavior at this kind of intersections seems to be vital. In this research drivers’ behavior in big cities in Iran at major-minor intersections has been studied. For this purpose, 7 major-minor intersections which have stop control at minor approach and median at major approach have been selected and shot. After extraction of primary data from taken digital video films and...
, M.Sc. Thesis Sharif University of Technology ; Vaziri, Manouchehr (Supervisor)
Abstract
As petroleum resources are not steadily distributed in the world and all industries and manufacturing sections are dependent on these resources, petroleum transportation is very important to the extent that availability of these resources occurs in the fastest time and costing the least possible. The objective of this study is to study the petroleum distribution through time in the world and assess its transportation efficacy during 1965-2005 in 173 countries. Collecting information about petroleum distribution between exporting countries to importing ones helped to complete the study data base. Also in this study two transportation networks, sea and land multimodal transportation network...
A Study of Trade and Transportation Trends in Asia
, M.Sc. Thesis Sharif University of Technology ; Vaziri, Manouchehr (Supervisor)
Abstract
Considering the extensive developments achieved up to now in the fields of trade and international transportation, as well as the key role of the freight transportation in the economical development of a zone or a country, the present research, titled “A Study of the Trade and Transportation Trends”, was planned. The available data concerning the trade of six types of the goods according to The United Nations Classification (SITC), within the period 1965-2005, have been analyzed in this research. The study has been focused on the Asian Multimodal Network constituted of 31 countries. Trading centre of each country in the selected network is assumed to be located in its capital town. The...
Activity-based Travel Demand Modeling in Rural Areas; Case Study of Villages Far-from-city in Fars Province
, M.Sc. Thesis Sharif University of Technology ; Vaziri, Manouchehr (Supervisor)
Abstract
Although rural inhabitants constitute a large portion of developing countries’ population, they have always been neglected in many ways. Expansion of equity, calls for a new concern in adequacy of rural development. The problem could be considered in two aspects: Firstly, there is a great tendency for immigration to nearby cities, hoping for a better life. This would result in more crowded cities, extended poverty and an increasing rate of crime mainly in suburban areas. On the other hand, the evacuation of farms and fertilized lands imposes great economical loss to the country. Therefore, development of rural facilities should be integrated into national policies to assure a homogeneous and...
Associating Vehicular Characteristics of Urban Fleet and Safety Factors with the Amount of Polluted Emissions
, M.Sc. Thesis Sharif University of Technology ; Vaziri, Manouchehr (Supervisor)
Abstract
One of the methods that have been used in order to mitigate the air pollution problem is the IM program in order to identify the high polluting vehicle and make them to adjust their engine in accordance to the emission standards. In Iran due to the air pollution problems the government operates a rudimentary IM program based on the idle engine test utilizing an exhaust gas analyzer which should be done annually. While IM programs usually regarded as a useful tool for soothing the air pollution, one of the criticisms about the program is that it is required for the entire fleet and it reduces the cost effectiveness of the program. This research studies the relationship between the vehicular...
Study of Traffic Flow Characteristics in Frontage Roads in Iran
, M.Sc. Thesis Sharif University of Technology ; Vaziri, Manouchehr (Supervisor)
Abstract
Frontage roads are widely used to separate the main and the local traffic flows in multilane highways. Based on the studies conducted by Texas Transportation Institute, the delay imposed by ramp junction is considered for calculating the average speed in frontage roads in addition to the control delay caused by traffic lights. This delay and the capacity of frontage roads are analysed using gap acceptance theory. In this study, two different sections consisting of a basic section and merge area are selected along Tehran-Karaj special road as case studies and the required data are collected by video recording. After classifying and analysing the data, a wide range of macro traffic-analyses...
A Survey on Passing Sight Distance on Two-lane highways According to Road Conditions and Drivers' Behavior in Iran
,
M.Sc. Thesis
Sharif University of Technology
;
Vaziri, Manouchehr
(Supervisor)
Abstract
The main factor ensuring safety of passing maneuvers on two lane highways is known as Passing Sight Distance (PSD). The criteria presented in Iran's code and AASHTO Green book are provided by the results of researches conducted between years 1938 & 1941 in the United States. This research intends to find out whether some changes should be applied to the PSD criteria according to current vehicles' performance and driving behavior in Iran. For this purpose, about 8 hours of video films has been recorded from 3 different sites chosen from two-lane highways in Iran, resulted in 326 passing records. In the case of passing of two passenger cars The models provided by analyzing the videos show that...
Design of an Algorithm for Automatic Incident Detection by Using Loop Detector Data Compatible to Traffic Conditions in Iran
, M.Sc. Thesis Sharif University of Technology ; Vaziri, Manouchehr (Supervisor)
Abstract
Incidents are one of the main sources of delays and they have significant influences on road safety and congestions, air pollution and trip costs. In the time of an incident occurrence, minimizing the response time is essential for several reasons. The most important issue is providing aid for the injured. The faster the persons who are severely injured receive aid, the higher their chances are to be rescued. Also, if the rescue crews get to the incident scene faster the clearance procedure would be accomplished faster and this would result in fewer disturbances in traffic stream and lowering the probability of secondary incidents occurrence. Automatic Incident Detection, AID, has been...
An Appraisal of the Trends of Trade and Transportation of Food Products Among Asia, Europe and Africa
, M.Sc. Thesis Sharif University of Technology ; Vaziri, Manouchehr (Supervisor)
Abstract
In this research, the trends of trade and transportation for the 10 subdivisions of food products and food products as a whole product based upon Standard International Trade Classification, SITC, have been appraised during the time period covering 1965 to 2005 among 125 countries in Asia, Europe and Africa. In this respect, the data of trade for the mentioned goods was gathered and other variables including gross domestic product, population, access to the international waters and area of countries and three transportation networks comprising two multimodal transportation networks and a unimodal network, during the cited period and for 125 countries was gathered. Then, regressions of trade...
Driver’s Behavior at Intersection with Yield Control in Minor Road
, M.Sc. Thesis Sharif University of Technology ; Vaziri, Manouchehr (Supervisor)
Abstract
Compared to systematically signalized intersections, in the absence of any systematic instruction or signalization at unsignalized-prioritized intersections and due to lower levels of control, driver performance strongly steps in as a decisive factor of intersection traffic and geometric design. Therefore, the study of driver behavior at these intersections appears necessary. This thesis aims to study driver behavior at four prioritized intersections where the minor stream has to yield right of way to the main stream in the city of Mashhad, Iran. Following extraction of raw statistical data from extensive filming, the initial database was constructed consisting of 29 variables. Based on the...