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mohammad--nasr-esfahani
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Enhancing Recommender Systems Using Analysis of Groups' Influence on Users in Social Networks
, M.Sc. Thesis Sharif University of Technology ; Habibi, Jafar (Supervisor)
Abstract
Rapid growth in science and technology has created vast diversity in products, services and needs of people and groups. As the Internet and web technologies have progressed, a web-based solution to explore products of either a specific domain or multiple domains is mandatory. One of the main challenges in these systems is learning users’ preferences to recommend items possibly interesting to the user. Social network of the users is one of the sources that can inject additional information about them which can be exploited to improve accuracy of the system. Depending on the method, the performance, accuracy and personalization may differ .One of the most popular methods to extract this...
The knowledge map of energy security
, Article Energy Reports ; Volume 7 , 2021 , Pages 3570-3589 ; 23524847 (ISSN) ; Bagheri Moghaddam, N ; Maleki, A ; Nazemi, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Much efforts have been made in the area of energy security in recent years, but due to its wide scope, it is necessary to review relevant knowledge activities and to analyze the state of knowledge of the field of energy security measurement. The purpose of this article is to present a comprehensive map of knowledge in the field of energy security. For this reason, many documents and articles have been collected during the period 2002–2019 using 7 large and reputable scientific databases as well as 53 different journals, 90% white Q1 quality. There is employed meta-synthesis, scientometrics and network analysis. In the initial survey stage where 1290 articles were found, after analyzing the...
MiR-9-5p and miR-106a-5p dysregulated in CD4+ T-cells of multiple sclerosis patients and targeted essential factors of T helper17/regulatory T-cells differentiation
, Article Iranian Journal of Basic Medical Sciences ; Volume 21, Issue 3 , March , 2018 , Pages 277-283 ; 20083866 (ISSN) ; Hosseini, A ; Ghaedi, K ; Kiani Esfahani, A ; Tanhaei, S ; Shiralian Esfahani, H ; Rahnamaee, S. Y ; Mowla, S. J ; Nasr Esfahani, M. H ; Sharif University of Technology
Mashhad University of Medical Sciences
2018
Abstract
Objective(s): Multiple sclerosis (MS) is considered as a chronic type of an inflammatory disease characterized by loss of myelin of CNS. Recent evidence indicates that Interleukin 17 (IL-17)-producing T helper cells (Th17 cells) population are increased and regulatory T cells (Treg cells) are decreased in MS. Despite extensive research in understanding the mechanism of Th17 and Treg differentiation, the role of microRNAs in MS is not completely understood. Thereby, as a step closer, we analyzed the expression profile of miR-9-5p and miR-106a-5p, and protein level of retinoic acid receptor (RAR)-related orphan receptor C (RORC; Th17 master transcription factor) as direct target of miR-106a-5p...
An Intelligent Dynamic Airspace Configuration (DAC) Decision Support System for Next Generation Air Transportation System (NGATS)
, M.Sc. Thesis Sharif University of Technology ; Malaek, Mohammad Bagher (Supervisor)
Abstract
For the past few years, increasing the airspace capacity has been one of the most detrimental issues facing air traffic management. Statistically speaking, the demand for aerial transportation has been continuously growing hitting an %8.1 growth in 2017. This growth rate in conjunction with the performance and safety considerations for the ATC systems, clearly indicate the need for a practical and safe solution to the airspace capacity problem. Dynamic Airspace Configuration (DAC), is one of the proposed methods addressing this problem by changing the airspace configuration over time.In this research, we have introduced an intelligent method for airspace configuration given the forecast of...
Effect of Oleuropein as Green Inhibitor on Corrosion Protection of Painted Steel
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
The corrosion rate of steel (EN 10130 DC-04) in the presence of oleuropein in aqueous corrosive solutions (of different concentrations in 1M and 0.5M hydrochloric acid and also 3.5% sodium chloride) evaluated and results was shown that oleuropein can protect steel surfaces and it acts as good inhibitor. This means that the observations of linear polarization and weight loss experiments showed inhibitor efficiency more than 97% in acidic corrosive medium and above 74% for aqueous solution of 3.5% sodium chloride. Adding oleuropein at different concentrations (i.e. 300 ppm, 700 ppm, and 1000 ppm) to three different types of polymeric paint structures (nitrocellulose alkyd base, acrylic base,...
Modification of Repair Welding on Control Valves and Flanges of Sure Gas
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor)
Abstract
In this research, for optimization of repair welding of control valve and flange that use in East Oil& Gas Company, effect of chemical composition, microstructure, hardness and stress relive on sulfide stress cracking (SSC) investigated with select of four electrodes. All welds were prepared by shielded metal arc welding (SMAW) and investigated with optical microscope, hardness test, tensile test and SSC test. The results showed that increase of nickel content in the range of 0.032–1.58 wt. % in weld metals, decrease of acicular ferrite and increase of side plate ferrite, grain boundary ferrite and M/A micro constituent in microstructure. Ni3S2 decrease SSC resistance and (FeCu).S increase...
To Investigate Existence of Equity Premium Puzzel in Tehran Stock Exchange By Stochastic Dominance Method
, M.Sc. Thesis Sharif University of Technology ; Keshavarz Haddad, Gholamreza (Supervisor)
Abstract
In the last 4 years, while the annual investment return on 5 years bank deposits was 25 percent; the total index of Tehran Stock Exchange on average grew by 155 percent. Why the investors are not so willing to invest in the stock market? This research deals with existence of equity premium puzzle in Tehran Stock Exchange. Therefore, the Total Price Index of exchange market is considered as a risky asset and the return on long-term (5 years) deposit is a proxy for risk free asset. Data is monthly and covers the first month of 1380 (Persian Calendar) to the beginning of the second month of 1391 (equivalent to Aug 2010 to Jan 2013); which is converted to real term using monthly inflation rate....
Hyperbolic Branching Brownian Motion
, M.Sc. Thesis Sharif University of Technology ; Esfahani Zade, Mostafa (Supervisor)
Abstract
Hyperbolic branching Brownian motion is a branching diffusion process in which individual particles follow independent Brownian paths in the hyperbolic plane H2, and undergo binary fission(s) at rate λ > 0. It is shown that there is a phase transition in λ : For λ ≤ 1/8 the number
of particles in any compact region of H2 is eventually 0, w.p.1, but for λ > 1/8 the number of particles in any open set grows to ∞ w.p.1. In the subcritical case (λ ≤ 1/8) the set Λ of all limit points in ∂H2 (the boundary circle at ∞) of particle trails is a Cantor set, while in the supercritical case (λ > 1/8) the set Λ has full Lebesgue measure. For λ ≤ 1/8 it is shown that w.p.1 the Hausdorff dimension of Λ...
of particles in any compact region of H2 is eventually 0, w.p.1, but for λ > 1/8 the number of particles in any open set grows to ∞ w.p.1. In the subcritical case (λ ≤ 1/8) the set Λ of all limit points in ∂H2 (the boundary circle at ∞) of particle trails is a Cantor set, while in the supercritical case (λ > 1/8) the set Λ has full Lebesgue measure. For λ ≤ 1/8 it is shown that w.p.1 the Hausdorff dimension of Λ...
Enⅽrypteⅾ Traffiⅽ Anaⅼysis through Expⅼainabⅼe Ⅿaⅽhine Ⅼearning
, M.Sc. Thesis Sharif University of Technology ; Jalili, Rasool (Supervisor)
Abstract
Impressive progress in hardwares and developing encryption algorithms in last two decades are caused increase in using encryption protocols in network communications. In last decade, users use privacy preserving networks like Jap and Tor to protect their privacy. These networks protect users' data from eavesdroppers by using three-layer encryption and intermediate nodes between user and target website. Recent researches show that Deep Neural Networks can predict websites viewed by users with high accuracy. In other words, privacy preserving networks suffer from information leakage. In this research, we introduced some of the most powerful methods in encrypted traffic classification and then...
A FEM-BEM Model for Investigation of Fuel SlushingEffect on the Supersonic Wing Aeroelasticity
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
In the present work the stability analysis for the coupled aeroelasticity and fuel sloshing in supersonic wings is represented. The wing and store structure is modeled using the finite element method. The supersonic wing aerodynamic is modeled by the linear piston theory and store aerodynamic is modeled by the semi-stable slender body piston theory. Fuel sloshing in the store with desired geometry is modeled by the boundary element method. The coupled structure, aerodynamic and sloshing governing equations are drawn by using the Galerkin method and reduce order modeling teqnique for them and an effective numerical model was developed that is capable to analyze the stability for...
Gravity in Noncommutative Geometry
, M.Sc. Thesis Sharif University of Technology ; Esfahani Zadeh, Mostafa (Supervisor)
Abstract
In this thesis, the aim is to stating some of the noncommutative geometry(NCG) applications in formulating and describing the gravity. So, in the first chapter, we will work on some of metric aspects of NCG. In this chapter, we will review elements of the spin geometry, specifically we will define the Dirac operator which is the most important object in this thesis. Then, we will try to find counterparts of some of Riemannian geometric notions like integral and distance in the NCG framework. We will define some notions such as noncommutative infinitesimals, Dixmier trace, Wodzicki residue, noncommutative integral and spectral triples. Then, in the second chapter, we will work on some of the...
Micromechanic Failure Analysis of Carbon/Phenolic Composite Conic Structures under Thermal Loading
, M.Sc. Thesis Sharif University of Technology ; Hosseini Kordkheili, Ali (Supervisor)
Abstract
In this study, through explaining a micromechanical model of progressive damage, failure in a composite conical structure under mechanical and thermal loads with 36 layers of carbon/phenolic material have been studied. To this end, first, mechanical behaviors of composite layers in micro and macro scale and their properties via fiber and matrix characterizations are discussed. In the following, selection of a proper RVE along with different types of boundary conditions on RVE are discussed. Then stress reinforcement coefficients in order to convert the mechanical and thermal stresses from macro to micro scale for carbon / phenolic material are extracted through defining appropriate RVE for...
Banks Money Creation and the Transmission Mechanism of Shocks
, M.Sc. Thesis Sharif University of Technology ; Madanizadeh, Ali (Supervisor) ; Mahmoodzadeh, Amineh (Supervisor)
Abstract
Banks are not only money brokers but also money creators. The ability of a bank to create money is due to its unique feature in issuing debts (deposits) that are accepted as a medium of exchange by economic agents. Although this bank function has been discussed under the "liquidity transformation" heading under the micro-banking literature, it has been less discussed in macro literature. In this study, we want to examine the consequences of the bank's liquidity transformation function by developing a New-Keynesian model in which banks can finance the economy by voluntarily expanding their balance sheet. To identify the mechanisms that the money creator bank creates in the model, we have...
Investigating Factors Affecting User Innovation in Mobile Phone Platforms
, M.Sc. Thesis Sharif University of Technology ; Khalili Nasr, Arash (Supervisor) ; Isaei, Mohammad Taghi (Supervisor)
Abstract
One of the main issues of business world is competition and competitiveness, and this cannot be happened unless one company absorb new ideas and innovations. Based on what scholars mentioned, companies should utilize users instead of professionals in order to create new innovations, and this is due to that users have better understanding of what users want. As a result, in the mobile platforms, platform owners need to know how to invoke users to create more innovative apps. In this research we were into finding important matters that increase number of innovation of users. We saw that lead-userness, toolkit support, work method autonomy, knowledge sharing, and modularity have an impact on...
Coupling 3D-1D for Blood flow Simulation in Carotid Bifurcation
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Saeedi, Mohammad Saeed (Supervisor)
Abstract
Recently, many investigations are done in the field of the modeling of the cardiovascular system. For the purpose of understanding of this system, mainly the location of formation and development of atherosclerosis, these investigations are so vital. The multi-scale modeling is an appropriate method to reduce the cost of calculation and also, this method simplifies the complicated model of cardiovascular system. This research presents a multi-scale 1D-3D modeling of cardiovascular system. In this model, the three dimensional geometry of carotid bifurcation is coupled with a one dimensional full model of cardiovascular system. We used some user defined function in the Fluent software for...
Investigating Distributed Denial of Service Attacks on MQTT Protocol And Proposal of New Attack Scenarios
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor) ; Salmasizadeh, Mahmoud (Co-Supervisor)
Abstract
MQTT (Message Queuing Telemetry Transport) is one of the essential and widely used protocols in the Internet of Things (IoT) networks. It operates at the application layer (Layer 7) for data transmission. As IoT applications using this protocol for communication have grown, securing such systems against security attacks has become a significant challenge. One of the important attacks implementable by IoT networks is Distributed Denial of Service (DDoS) attacks. In this thesis, we initially provide a general overview of IoT security and demonstrate how DDoS attacks disrupt the availability feature in these networks. We then examine known types of DDoS attacks to gain a better understanding of...
A higher index theorem for foliated manifolds with boundary
, Article Bulletin des Sciences Mathematiques ; Volume 136, Issue 2 , 2012 , Pages 201-238 ; 00074497 (ISSN) ; Sharif University of Technology
2012
Abstract
Following Gorokhovsky and Lott and using an extension of the b-pseudodifferential calculus of Melrose, we give a formula for the Chern character of the Dirac index class of a longitudinal Dirac type operators on a foliated manifold with boundary. For this purpose we use the Bismut local index formula in the context of noncommutative geometry. This paper uses heavily the methods and technical results developed by E. Leichtnam and P. Piazza
On vanishing of low-degree higher Â-genera
, Article Differential Geometry and its Application ; Volume 43 , 2015 , Pages 56-59 ; 09262245 (ISSN) ; Sharif University of Technology
2015
Abstract
In this short note we apply methods introduced by B. Hanke and T. Schick to prove the vanishing of (low degree) higher Â-genera for spin manifolds admitting a positive scalar curvature metric. Our aim is to provide a short proof for this beautiful result
Study and Fabrication of Flexible and Stretchable Electronic Circuits
, M.Sc. Thesis Sharif University of Technology ; Sarvari, Reza (Supervisor) ; Kolahdouz Esfahani, Mohammad Reza (Supervisor)
Abstract
In recent years, flexible electronics have started to attract a tremendeos amount of attention, partly on its remarkable growth in new technologies like IoT, wearable electronics, personal and health care devices. This emerging field offers many advantages compared to its traditional rigid counterparts, such as bendability, stretchablity, recyclability and biocompatibility. Inkjet printing is one of the most promising method for realizing flexible electronics due to its low-investment cost, fully additive nature, low material westage, relatively low temperature process and non-contact patterning.A printed circuit board (PCB), is undoubtedly a vital part of any electronics systems. So,...
Robust Design Optimization for Fatigue Life with Geometric and Material Uncertainties of Mechanical Parts Under Random Loading Based on Maximizing Fatigue Life and Minimizing Uncertainty in Fatigue Llife Prediction
, M.Sc. Thesis Sharif University of Technology ; Khodaygan, Saeed (Supervisor)
Abstract
Fatigue life prediction of a mechanical part is one of issues which a group of engineers are engaged with it and always they try to design the parts with the maximum of lifetime. Although many researches have been done in this field but yet we can see that predicted life are different from that happens in the reality because there are some uncertainties in the phenomena. Our effort in this project is creating an algorithm design so that the parts are designed by it, have the maximum fatigue life and the minimum uncertainty in prediction. In this project we have considered geometrical, material and random loading uncertainties as error resources. Older methods those are presented in this...