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jahanbakhsh--amir-mohammad
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Flight Management of an E-VTOL Fleet Using ANFIS Network
, M.Sc. Thesis Sharif University of Technology ; Malaek, Mohammad Bagher (Supervisor)
Abstract
Much research has been done in the field of queuing or forecasting aircraft routes. These methods have been implemented mainly for commercial aircraft, and little research has been done on electric birds. In this research, we intend to extend these methods to the field of electric birds and create a database based on the existing records of successful flights that electric birds have had in the landing phase. Next, design an intelligent learning system that adjusts its parameters and has the ability to predict the route for birds planning to land at an airport. This intelligent system can manage the birds that are going to land with high computational speed and keep it up to date by adding...
Synthesis of Nano Porous Mixed Matrix Polymeric Membranes by TIPS Method for Gas Separation Application
, M.Sc. Thesis Sharif University of Technology ; Soltanie, Mohammad (Supervisor)
Abstract
Mixed matrix membranes (MMMs) are new generation of membranes which possess simple processability of polymeric membranes and high separation ability of zeolitic membranes. The present study, concentrates on the fabrication of MMM for CO2/CH4 separation in a combined method as encompasses not only higher permeability but also superior selectivity in comparison with conventional polymeric membranes. The most appropriate technique for MMM making, is the process which provides participation of distributed zeolite particles in separation efficiently while the polymeric matrix acts just like a particle support and dose not play an effective role in separation. Investigations demonstrates that...
Low Temperature Performance Evaluation of Modified Asphalt Binders
, M.Sc. Thesis Sharif University of Technology ; Tabatabaei, Nader (Supervisor)
Abstract
Low temperature cracking is the most important type of asphalt pavement distress that occurs in cold climates. Up until the development of performance grading (PG) based binder specification, there was no irect indication of low temperature suitability of asphalt binders. PG specification was mainly developed for and validated by neat binders.
With increased use of modified asphalt binders in recent years, some of the limitations and shortcomings of the original PG specifications have surfaced.Considering that low temperature cracking is a fracture failure, it was hypothesized that tests based on the fracture mechanics and fracture energy parameter can lead to better classification of...
With increased use of modified asphalt binders in recent years, some of the limitations and shortcomings of the original PG specifications have surfaced.Considering that low temperature cracking is a fracture failure, it was hypothesized that tests based on the fracture mechanics and fracture energy parameter can lead to better classification of...
Content Delivery Network Optimization via Streaming Analytics
, M.Sc. Thesis Sharif University of Technology ; Habibi, Jafar (Supervisor)
Abstract
Content delivery over the Internet is limited by the distance between the website or application server and the end user, so the further the server is from the end user, the longer it takes for the website content to load. Content delivery servers play an important role in improving the performance of Internet services by placing the content needed by users in cached servers close to users and reducing the distance that data must travel. In a content delivery network, a large number of geographically distributed edge servers are deployed, and whenever a user requests a content, the desired content is downloaded from the nearest edge server. Currently, more than half of the internet traffic...
Driving Behavior Estimation with Smartphone Data
, M.Sc. Thesis Sharif University of Technology ; Samimi, Amir (Supervisor)
Abstract
Identifying driving behaviors and building an efficient and accurate driving behavior recognition model is of paramount importance for improving driving safety. Nowadays, with the ubiquity of smartphone sensors, many researchers are using smartphone sensory data to create models which forecast driving behaviors. This research introduces a logit model that predicts nine types of driving events using accelerometer and gyroscope sensors with an accuracy of 76 percent
Drag force on a flat plate in cavitating flows
, Article Polish Maritime Research ; Volume 16, Issue 3 , 2009 , Pages 18-25 ; 12332585 (ISSN) ; Asnaghi, A ; Jahanbakhsh, E ; Sharif University of Technology
2009
Abstract
The present study focuses on the simulation of two dimensional unsteady cavitating flows. For simulation of unsteady behaviors of cavitation which have practical applications, the development of unsteady PISO algorithm based on the non-conservative approach is utilized. For multi-phase simulation, single-fluid Navier-Stokes equations, along with the volume fraction transport equation, are employed. The bubble dynamics model is utilized to simulate phase change between vapor and liquid phases of the water. Unsteady simulation of cavitation around NACA66(MOD) and supercavitation around a flat plate normal to flow direction are performed to clarify accuracy of presented model. Numerical results...
Chaotic Network Flows in an Evolutionary Model of Traffic Assignment Based on Speed and Density
, M.Sc. Thesis Sharif University of Technology ; Poorzahedy, Hossein (Supervisor)
Abstract
Chaotic Flow in transportation networks has been the subject of several studies. Evolutionary models have been employed to simulate traffic flows. This study takes advantage of an existing evolutionary model of traffic assignment to show that chaotic phenomena arise when the model’s driving force is speed or density, of traffic flow. It has been observed that drivers show higher sensitivity when the network is more loaded.
Thermal Simulation of Sponge Iron Production by Höganäs Method
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
Sponge Iron production is conducted in various methods that one of them is using coal as a reduction agent. Hoganas process is a different coal-based method that has not been investigated in details. Therefore, the heat transfer method in the system is one of the basic steps to a better recognition of this process (with special Hoganas charging). The present paper investigates the temperature distribution method in the Hoganas cylinder through a numerical model using finite elements. The effects of different parameters, namely preheating and porosity were studied on ceramic crucible made from silicon carbide and it was observed that the consumption energy decreases with the increase of...
Consequence Modelling and Probabilistic Risk Assessment of Oil Spills in the Marine Waters
, Ph.D. Dissertation Sharif University of Technology ; Raie, Mohammad (Supervisor)
Abstract
Different causes in the exploration, production and transport of oil in the marine environment result in oil spill events. Since elimination of the probability of occurrence of spills is not possible, it is important to have a plan to control the risk of oil spills by optimal response. In this research, a general stucture is presented for the DSS required for oil spill response planning. This system can be used for evaluation of the effectiveness of response drills, and risk-based ranking of receptor areas and spill sources. Ranking based on risk is realized through probabilistic or stochastic risk assessment. The applicability of the proposed system is examined in differnet case studies in...
Preparation and characterization of SAPO-34 nanoparticles-mixed matrix membranes (MMM) via combined phase separation method for CO2/CH4 gas separation application
, Article Technical Proceedings of the NSTI Nanotechnology Conference and Expo, NSTI-Nanotech ; Vol. 1 , 2014 , pp. 253-256 ; ISBN: 9781482258264 ; Soltanieh, M ; Azadi, R ; Sharif University of Technology
2014
Abstract
Phase separation is one of the common methods for fabrication of polymeric membrane, which classifies into the categories of Thermally Induced Phase Separation (TIPS) and Nonsolvent Induced Phase Separation (NIPS), i.e. heat and mass transfer induced phase separation, respectively. NIPS has been applied more commonly than TIPS, but the membranes which have resulted from this technique have macro finger-like voids, weak mechanical strength and not high separation ability in comparison with the TIPS. In contrast, membranes produced by the TIPS method have micro scale pores, high mechanical strength and also high separation capability, however, polymeric solutions prepared at high temperatures...
Experimental and numerical investigation of low-temperature performance of modified asphalt binders and mixtures
, Article Road Materials and Pavement Design ; 2016 , Pages 1-22 ; 14680629 (ISSN) ; Karimi, M. M ; Tabatabaee, N ; Sharif University of Technology
Taylor and Francis Ltd
2016
Abstract
Thermal cracking is the prevalent type of distress experienced by asphalt pavements in cold regions. It is widely assumed that when thermal stresses induced in the pavement exceed the tensile strength of the asphalt surface layer, cracking occurs; however, the role of thermal fatigue should not be ignored. To better describe the low-temperature (LT) performance properties of modified asphalt binders, a new parameter, normalised tensile stress (NTS), was defined in this research. NTS values were compared with bending beam rheometer (BBR), direct tension (DT) and semi-circular bending (SCB) fracture test results. The m-value parameter of the BBR test specifies the type of asphalt binder. This...
Implementation of PISO algorithm for simulating unsteady cavitating flows
, Article Ocean Engineering ; Volume 37, Issue 14-15 , 2010 , Pages 1321-1336 ; 00298018 (ISSN) ; Asnaghi, A ; Jahanbakhsh, E ; Sharif University of Technology
2010
Abstract
The present study focuses on the implementation of PISO algorithm to simulate cavitating flows. For simulation of unsteady behaviors of cavitation which have practical applications, the development of unsteady PISO algorithm based on the non-conservative approach is investigated. The effects of mixture compressibility are considered to improve accuracy of simulations. For multi-phase simulation, single-fluid Navier-Stokes equations, along with the volume fraction transport equation, are employed. The bubble dynamics model is utilized to simulate phase change. To prove capabilities of the developed PISO algorithm to simulate cavitating flows, unsteady simulation of cavitation around NACA0015...
Catamaran motion simulation based on moving grid technique
, Article Journal of Marine Science and Technology ; Volume 17, Issue 2 , 2009 , Pages 128-136 ; 10232796 (ISSN) ; Panahi, R ; Seif, M. S ; Sharif University of Technology
2009
Abstract
General purpose software is developed to simulate 6-DoF fluid-structure interaction in two-phase viscous flow. It is a VoF-fractional step solver based on the finite-volume discretization which uses a boundary-fitted body-attached hexahedral grid as the motion simulation strategy. As an application, a high-speed planing catamaran is simulated in steady forward motion as well as in turning maneuver. Results are compared with the available data and good qualitative and quantitative agreements are achieved. Numerical schemes and the solution algorithm of the software are consistent and show a good capability to model highly nonlinear ship motions. It can be further developed to represent a more...
Experimental and numerical investigation of low-temperature performance of modified asphalt binders and mixtures
, Article Road Materials and Pavement Design ; Volume 18, Issue 6 , 2017 , Pages 1353-1374 ; 14680629 (ISSN) ; Karimi, M. M ; Tabatabaee, N ; Sharif University of Technology
2017
Abstract
Thermal cracking is the prevalent type of distress experienced by asphalt pavements in cold regions. It is widely assumed that when thermal stresses induced in the pavement exceed the tensile strength of the asphalt surface layer, cracking occurs; however, the role of thermal fatigue should not be ignored. To better describe the low-temperature (LT) performance properties of modified asphalt binders, a new parameter, normalised tensile stress (NTS), was defined in this research. NTS values were compared with bending beam rheometer (BBR), direct tension (DT) and semi-circular bending (SCB) fracture test results. The m-value parameter of the BBR test specifies the type of asphalt binder. This...
Numerical simulation of three-dimensional interfacial flows
, Article International Journal of Numerical Methods for Heat and Fluid Flow ; Volume 17, Issue 4 , 2007 , Pages 384-404 ; 09615539 (ISSN) ; Panahi, R ; Seif, M. S ; Sharif University of Technology
2007
Abstract
Purpose - This study aims to present compatible computational fluid dynamics procedure for calculation of incompressible three-dimensional time-dependent flow with complicated free surface deformation. A computer software is developed and validated using a variety of academic test cases. Design/methodology/approach - Two fluids are modeled as a single continuum with a fluid property jump at the interface by solving a scalar transport equation for volume fraction. In conjunction, the conservation equations for mass and momentum are solved using fractional step method. Here, a finite volume discretisation and colocated arrangement are used. Findings - The developed code results in accurate...
Investigating Effects of Urban Freight Companies' Scale on their Transport Efficiency and Developing a Tool for Integration of Freight Companies
, M.Sc. Thesis Sharif University of Technology ; Samimi, Amir (Supervisor) ; Kermanshah, Amir Hassan (Supervisor)
Abstract
In this research, a dashboard has been developed to support decision-making in the integration of freight companies. Freight companies usually consist of a limited number of vehicles due to the high cost of vehicles, while the fixed costs of a freight company constitute a significant part of that company's total cost. Therefore, if these companies are merged, their total cost will be substantially decreased. Moreover, under particular demand levels, the integration of freight companies reduces the mileage, travel time, and the number of required cars. Therefore, the integration of freight companies not only reduces fixed costs but also reduces other costs including greenhouse gas costs by...
Climatic Map of Atmospheric Corrosion of Iran
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Atmospheric corrosion as one of the most principal factors of destruction is not Climatic map of atmospheric corrosion is closely related to air and atmospheric factors among which we can point out to different types of atmospheric pollutions such as NOX, SOX gases and pendant materials as well as the rate of humidity and rain and even the rate of sun radiation. The effects of these factors beside each other cause the speed of corrosion from a climate to another climate to be changed, which is presentable in form of a map. There is a 2 method to provide this map. First build up a station to measure the corrosion data and collect them in a long period of time. This method are time consuming...
Reconfigurable Architecture For Cryptanalysis Applications
, M.Sc. Thesis Sharif University of Technology ; Jahangir, Amir Hossein (Supervisor)
Abstract
Nowadays, the significance of securing data and information is undeniable. Cryptography is being used to provide data security. In addition, cryptanalysis is required to evaluate the effectiveness of cryptography methods, and hence, it is an essential concept for securing data. In general, the cryptography functions shall be designed in a way to impose a high load of time-intensive operations to prevent an adversary from accessing the main data from the encrypted data. As a result, cryptography and cryptanalysis algorithms need high performance computations. So far, a number of methods have been proposed to support the required performance. These methods include: distributed computing and...
Regularization from the Machine Learning Point of View
, M.Sc. Thesis Sharif University of Technology ; Daneshgar, Amir (Supervisor)
Abstract
In traditional machine learning approaches to classification, one uses only a labeled set to train the classifier. Labeled instances however are often difficult, expensive, or time consuming to obtain, as they require the efforts of experienced human annotators. Meanwhile unlabeled data may be relatively easy to collect, but there has been few ways to use them. Semi-supervised learning addresses this problem by using large amount of unlabeled data, together with the labeled data, to build better classifiers. Because semi-supervised learning requires less human effort and gives higher accuracy.Formally, this intuition corresponds to estimating a label function f on the graph so that it...
On the Density Matrix of Graphs
, M.Sc. Thesis Sharif University of Technology ; Daneshgar, Amir (Supervisor)
Abstract
Density matrix of graphs as defined -for the first time- in [S. Braunstein and et al. The laplacian of a graph as a density matrix, Annals of Combinatorics, (2006)], is obtained through dividing the Laplacian matrix by the degree sum. This matrix is also semi-positive and trace one. Therefore one may talk about the Von Neumann entropy of this matrix. In [F. Passerini, S. Severini. Quantifying complexity in networks: The Von Neumann entropy. IJATS, (2009)], authors have claimed that this quantity can be consisered as a measure of regularity. Here, using a geometric interpretation of Von Neumann entropy, expresed in [G. Mitchison, R. Jozsa, Towards a geometrical interpretation of quantum...