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fekri-dabanloo--yousef
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On Zero Divisor Graphs
, M.Sc. Thesis Sharif University of Technology ; Mahdavi Hezavehi, Mohammad (Supervisor)
Abstract
We survey the research conducted on zero divisor graphs, with a focus on zero divisor graphs determined by equivalence classes of zero divisors of a commutative ring R. In particular, we consider the problem of classifying star graphs with any finite number of vertices. We study the pathology of a zero divisor graph in terms of cliques, we investigate when the clique and chromatic numbers are equal, and we show that the girth of a Noetherian ring, if finite, is 3. We also introduce a graph for modules that is useful for studying zero divisor graphs of trivial extensions
Comparison of synthesis and purification of carbon nanotubes by thermal chemical vapor deposition on the nickel-based catalysts: NiSio2 and 304-type stainless steel
, Article Journal of Applied Sciences ; Volume 10, Issue 9 , 2010 , Pages 716-723 ; 18125654 (ISSN) ; Jafari, A ; Fekri, S ; Shafikhani, A ; Vesaghi, M ; Behzadi, G ; Sharif University of Technology
2010
Abstract
In this study by Thermal Chemical Vapor Deposition (TCVD) method, the synthesis of carbon nanotubes (CNTs) and temperature affects on the grown CNTs on the NiSio2 catalyst and 304-type stainless steel was investigated. The purification of the grown CNTs on the 304-type stainless steel was also investigated in this study. The synthesis and purification of the samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), termogravimetric analysis (TGA) and Raman spectroscopy. Our obtained result by SEM and TEM shows that densities of CNTs growth on the 304-type stainless steel are more than the CNTs growth on the NiSio2 catalyst and both of them have...
Angle of attack estimation and aircraft controller design using LQR methods
, Article Canadian Conference on Electrical and Computer Engineering 2005, Saskatoon, SK, 1 May 2005 through 4 May 2005 ; Volume 2005 , 2005 , Pages 2253-2256 ; 08407789 (ISSN) ; Mobed, M ; Sharif University of Technology
2005
Abstract
An LQ-based tracker is designed in this paper, using output feedback. For performing the design, at first, a structured controller is introduced for a set of equations. The controller is obtained by mini-mizing a cost function which has some penalties on both the system's inputs and states. After that, an estimator is introduced and combined with the controller to close the loop. Running the nonlinear simulation at the end verifies the superiority of Extended Kalman Estimator (EKF)to the Linear Kalman Estimator (LKF). © 2005 IEEE
Evaluating valence level of pictures stimuli in heart rate variability response
, Article 42nd Computing in Cardiology Conference, CinC 2015, 6 September 2015 through 9 September 2015 ; Volume 42 , 2015 , Pages 1057-1060 ; 23258861 (ISSN); 9781509006854 (ISBN) ; Moharreri, S ; Jafarnia Dabanloo, N ; Parvaneh, S ; Sharif University of Technology
IEEE Computer Society
2015
Abstract
Low and high valence were induced in 20 male volunteers using two groups of pictures stimuli. Heart response was compared between two groups from RR series extracted from recorded ECG measurements. Mean heart rate and heart rate variability measures including time, frequency and Poincare domain were extracted. The results revealed that HRV triangular index, SDNN and SD2 were the only statistically significant parameters between groups (p<0.05). Mean heart rate and power in LF and HF bands were also different between low and high valence groups however level of significance was not reached. © 2015 CCAL
On the capacity of level and type modulations in Molecular communication with ligand receptors
, Article IEEE International Symposium on Information Theory - Proceedings, 14 June 2015 through 19 June 2015 ; Volume 2015-June , 2015 , Pages 1951-1955 ; 21578095 (ISSN) ; 9781467377041 (ISBN) ; Mirmohseni, M ; Nasiri Kenari, M ; Fekri, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper, we consider the bacterial point-to-point communication problem with one transmitter and one receiver by considering the ligand receptor binding process. The most commonly investigated signalling model, referred to as the Level Scenario (LS), uses one type of a molecule with different concentration levels for signaling. An alternative approach is to employ multiple types of molecules with a single concentration level, referred to as the Type Scenario (TS). We investigate the trade-offs between the two scenarios for the ligand receptor from the capacity point of view. For this purpose, we evaluate the capacity using numerical algorithms. Moreover, we derive an upper bound on the...
Finite Element Analysis of Reinforced Concrete Waffle Slabs in Steel Structures “Strength Conditions”
, M.Sc. Thesis Sharif University of Technology ; Eskandari, Morteza (Supervisor) ; Kazemi, Mohamad Taghi (Supervisor)
Abstract
Building weight reducing idea and implementation of Lightweight Structures were always attractive for structural engineering experts, scholars and researchers around the world and its proven effects on improving behavior and reducing the forces acting on the structure, has urged researchers to create new designs. Concrete slabs are of a significant portion of the overall weight of the structure. Nowadays, waffle slabs are a demand for structural designers, as a consequence of architectural design evolution and new building management concepts, in spite of its laborious numerical modeling. The objective of this work was to analyze the adequacy of a design method widely used in the modeling of...
Coordinated Scheduling in Public Transportation to Decrease Transfer Waiting Time Through Slight Changes in Headways
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
Decreasing travel time is one of the main goals of passengers in urban areas for which transportation operators use various policies. Among these policies, expanding public transportation facilities is one of the urban planner major purposes. Considering the fact that making these facilities needs great investment, optimize use of the current facilities is valuable. Waiting time in transit station has influence on increasing passengers’ travel time and inconsistency, so coordination between different transit lines is necessary. In this thesis, creating coordination among different transit lines in a transit network by the use of integer programming is studied in the form of two models. In...
An Applied Model for Highway Alignment Optimization Using Particle Swarm Optimization Method
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
A basic highway design problem is to find the most economical alignment connecting two given end points based on topography, soil conditions, socioeconomic factors and environmental impacts, while satisfying a set of design and operational constraints. The cost function complexity and numerous limitations such as highway design criteria have made this problem a NP-hard one. In this study, a swarm based searching algorithm has been applied to a three dimensional highway alignment optimization model. The spatial data has been exploited from a GIS databases using a heuristic swift approach. In addition, the majority of cost items that depend on highway design have been extended in a practical...
Route Choice Estimation Using Cell Phone Data
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
Knowing the trip information such as paths that travelers prefer to choose is useful for practice in developing certain transportation planning step. There are different methods such as using GPS and conducting survey for volunteer travelers in order to understand actual paths. Obviously, all of these methods have some deficiencies. This research suggests and examines a method for estimating travelers’ path by using cell phone data. The main advantage of using these kinds of data is enabling the process of collecting information without any active interference of the users. A big data set consisting of 300,000 cell phone users’ information in the city of Shiraz is studied to achieve this...
Determining Mode of Travel Using Cell Phone Data
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
There has been growing interest in exploiting cellular network data for transportation planning purposes in recent years. In this thesis, we utilize these data for determining mode of travel in the city of Shiraz, Iran. Cellular data records -including location updates in 5minute time intervals- of 300,000 users from the city of Shiraz has been collected for 40 hours in three consecutive days in a cooperation with the major telecommunications service provider of the country. Depending on the density of mobile BTS’s in different zones of the city, the user location can be located within an average of 200 meters. Considering data filtering and smoothing, data preparation and converting them to...
Estimating Activity Patterns Using Spatio-temporal Data of Cell phone Networks
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
The tendency towards using activity-based models to predict trip demand has increased dramatically over recent years, but these models have suffered insufficient data for calibration and the intrinsic problems of traditional methods imposes the need to search for better alternatives. This paper discusses ways to process the cellphone spatio-temporal data in a manner that makes it comprehensible for traffic interpretations and proposes methods on how to infer urban mobility and activity patterns from the aforementioned data. Movements of each subscriber is described by a sequence of stays and trips and each stay is labelled by an activity. The type of activities are estimated using features...
Estimation of Origin-Destination Trip Matrix Using Mobile Phone Network’s Spatiotemporal Dataset
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
Knowledge about travel demand patterns is an important requirement for strategic planning and management of urban transportation networks. Use of theoretical trip distribution models such as growth, gravity or intervening opportunities, estimation with the help of questionnaire surveys and development of volume- based O-D estimation methods have been major fields of scientific efforts in recent years.Rapid changes in land use and transportation networks especially in developing countries has raised the importance level of knowledge about changes in travel demand.Traditional approaches are costly, time consuming and suffer from inaccuracies, so,...
Flight Rescheduling After Perturbation with Crew Constraints
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
Airlines spend considerable time, effort and financial resources on planning. It is essential to create a competitive timetable and construct a fleet and a crew schedule that utilizes these resources to maximum. Unfortunately, it is all too common that an airline is faced with the necessity of reconstructing their schedule due to some unforeseen event such as an aircraft breakdown or unsuitable weather condition. Rescheduling flight in such conditions is inevitable. In this article, first, a mathematical model is presented to minimize the expense caused by aircraft breakdown, flight delay and airport closure with considering crew constraints. Cancellation, delay, aircraft swaps and replacing...
A Comprehensive Model for Aircraft Maintenance Routing
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
One of the fundamental constraints that should have been in mind in flight scheduling is aircraft maintenance scheduling. Based on the accepted rules, regulations and flight safety, in a given period of time or after definite number of flight hours each aircraft should be sent to maintenance site. This influences the flight schedule. This research provides a comprehensive model for the flight scheduling. Given the flight schedule, number of the flights and aircrafts, maintenance center's capacity and other parameters such as each check's time, allowable flight days and allowable flight hours this model could determine each season's flight schedule and solve the aircraft routing problem....
Estimation of Origin-Destination Trip Matrix Using Spatio-Temporal Data of Cell Phone Networks Collected based on the PLU method
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
Origin-destination (OD) matrix is one of the most important sources of information used in planning and management of transportation networks. Estimation of a precise OD matrix is a fundamental component for enabling the administrative authorities to optimize the use of their transportation network. Traditionally, urban planners use direct approaches including household questionnaires to estimate OD matrices. These methods are time-consuming and costly. Strategies that are more recent like Bluetooth, Wi-Fi, and RFID scanners and detectors include deficient precision and the additional cost of accessories. Exploiting GPS technology in spite of its high locating accuracy, due to user...
Trip-Chain-Based Travel-Mode-Shares Driven Framework Using Mobile Data
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
The costly and time-consuming methods of traditional data collection through interviews or questionnaires have led researchers to use new methods, including mobile networks, to obtain the information they need. Information obtained from the mobile network has been widely used in recent studies due to features such as passive information generation, extensive coverage and low cost of data collection, and attempts have been made to use this information to model citizens activities and urban travel demand. However, extracting information such as travel patterns and mode share of transportation has been challenging given the nature of this type of data. This research pursues two goals separately...
Urban Mobility Pattern Estimation Using O-D Surveys and Mobile Phone Data: A Case Study of Shiraz City
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
Activity bases models of travel demand considers travel demand as a derived demand to fulfill activities. Development of these models cause better understanding of the mechanism of travel through Integrity, interdependencies, higher temporal and spatial aggregation, and behavioral basis. Although these models requires of spatial and temporal data with high resolution of huge number of peoples. Gathering this data through surveys require great labor and time. Mobile phone data of cellular network have high spatial-temporal resolution used for billing purposes and can be used as a supplementary source of data to develop activity based models. This research uses mobility patterns called motifs...
The Impacts of Autonomous Vehicles on Parking Demand in Urban Areas
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
Autonomous vehicles will have a major impact on parking demands in urban areas in the future. Compared to conventional vehicles that should park near the destination of the passengers, autonomous vehicles can drop off the travelers at their destinations and then drive to the parking spaces by themselves. However, choosing a parking space in a far zone from the destination could lead to more travel demand in the network. We investigate traffic network equilibrium for traveling and parking with autonomous vehicles under a fully automated traffic environment. We introduce a Bi-level model, considering parking choices in the upper level and route choices in the lower level. The upper-level...
A Model to Predict the Railway Track Deterioration and Provide a Decision-Support System for Maintenance by Life Cycle Cost
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
Rail transport system plays an important role in the development of the economies of the countries. This system is worn out over time by operating and weather conditions and requires maintenance and repair. One of the objectives of maintenance operations is to maintain tracks in an acceptable level and prevent their excessive deviation from the optimal situation. This deviation is called geometric irregular deviation. If these irregularities go away, they can cause traffic accidents and derailment in addition to losing travel convenience. So avoiding the deviation of the tracks is a very important. Maintenance management systems in the past few decades have been considered by the experts in...
Origin-Destination Matrix Adjustment using Split Ratios of Network Nodes
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yousef (Supervisor)
Abstract
This research presents a model to adjust origin-destination (OD) matrix using split ratios of network nodes. Conventional direct methods for OD estimation are resource intensive and time consuming therefore developing indirect methods which are less costly is important. Split ratios of network nodes can be obtained from nowadays technologies such as Bluetooth sensors with acceptable accuracy. An iterative bilevel estimation framework is presented that uses split ratios and link flows as observations. The upper level problem is to minimize a weighted objective function of the deviation between observed and estimated data. In the lower level the OD matrix is assigned to the network. This model...