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ghandi-falizani--mehdi
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Simulation of Plasma Gasification and Power Generation Based on Solid Waste
, M.Sc. Thesis Sharif University of Technology ; Saboohi, Yadollah (Supervisor)
Abstract
Along with the development of social and economical development and expansion of urban areas the rate of municipal solid waste (MSW) generation has been increased. Waste-to-Energy technologies consist of any waste treatment process that enables generating energy from a waste source. In recent years many studies have shown that plasma gasification has a considerable potential as an effective method for solid waste treatment and energy recovery. Plasma gasification converts MSW to a clean syngas and its application could reduce MSW volume and the environmental risks of waste landfill. In the present study the methods of waste conversion to energy has been reviewed, then plasma gasification of...
Analyzing IoT System Using Location-Base Data
,
M.Sc. Thesis
Sharif University of Technology
;
Gholampour, Iman
(Supervisor)
Abstract
Nowadays, using different types of data has shown significant impacts on analyzing the related systems. Growth in data volume, systems complexity and existence of error and obscurity in collecting the data, increased the necessity of inventing new data analysis methods. Location-based data is an important data type for such analyses which are collected from sensors in different places. These data besides other official organization's information like municipality or Google … provide us a bulk volume of raw data. Such collections of raw data are mostly diverse, heterogeneous, bulk and outspread. Inspite of that, raw data with machine learning algorithms lead to considerable practical...
Sales and Marketing Cooperation: Mechanisms and Consequences
, Ph.D. Dissertation Sharif University of Technology ; Najmi, Manoochehr (Supervisor)
Abstract
Previous studies and field evidences show that creating appropriate interactions between sales and marketing departments is a challenge for many organizations. The main objective of this research is to develop and elaborate a conceptual framework in which "cooperation mechanisms" between sales and marketing and it’s "consequences" determined and provide an explanation that shows how configuration of sales and marketing relationship affects its consequences. The results show that "organizational ambidexterity" is the core consequence in proper architecture of the relationship between sales and marketing. In the strategy literature, combination of the dual capabilities of exploration and...
A Framework for Identifying Critical Areas in Urban Road Networks Based on Percolation Theory Using Real Data
, M.Sc. Thesis Sharif University of Technology ; Amini, Zahra (Supervisor)
Abstract
Transportation networks serve as the primary foundation for economic growth and the development of nations. These networks play a pivotal role by facilitating the movement of goods and passengers, as well as providing essential resources for human activities. With the rapid urbanization and increasing population in cities, the importance and efficiency of these networks have become even more critical. Among the significant challenges faced in urban areas is traffic congestion, which leads to substantial costs, including wasted time and energy, and has negative impacts on public health. As a result, numerous studies have been conducted on the formation and spread of congestion in streets and...
Some nonlinear/adaptive methods for fast recovery of the missing samples of signals
, Article Signal Processing ; Volume 88, Issue 3 , 2008 , Pages 624-638 ; 01651684 (ISSN) ; Jahani Yekta, M. M ; Marvasti, F ; Sharif University of Technology
2008
Abstract
In this paper an iterative method for recovery of the missing samples of signals is investigated in detail, and some novel linear, nonlinear, and adaptive extrapolation techniques are proposed to be used along with it to increase the convergence rate of the recovery system. The proposed methods would remarkably speed up the convergence rate, save processing power, and reduce the delay of the system compared to some well known accelerated versions of the aforementioned iterative algorithm. © 2007 Elsevier B.V. All rights reserved
A novel context modeling scheme for motion vectors context-based arithmetic coding
, Article Canadian Conference on Electrical and Computer Engineering; Technology Driving Innovation, 2004, Niagara Falls, 2 May 2004 through 5 May 2004 ; Volume 4 , 2004 , Pages 2021-2024 ; 08407789 (ISSN); 0780382536 (ISBN) ; Ghandi, M. M ; Shamsollahi, M. B ; Sharif University of Technology
2004
Abstract
In this paper a new context modelling scheme for arithmetic coding of Motion Vectors (MVs) is proposed. The model uses the correlation between the horizontal and vertical components of MVs to improve the probability estimation of symbols. The accurate probability estimation can therefore improve the efficiency of the context-based arithmetic coder. The proposed scheme has been adapted to the H.264 advanced video codec and the simulation results show that a considerable bit rate saving can be achieved in MV coding
Design and Fabrication of Inductive High Temperature Superconducting Fault Current Limiter
,
Ph.D. Dissertation
Sharif University of Technology
;
Vakilian, Mehdi
(Supervisor)
;
Fardmanesh, Mehdi
(Supervisor)
Abstract
The continuous rise in electricity demand and the ever growing power generation in different power networks over the world have caused the short circuit level in the power systems to exceed the operational rating of the installed power devices (including cables, circuit breakers and buses). Replacing these devices with new higher rating devices is an expensive solution. From this point of view, utilizing fault current limiters is an economical solution. Superconducting fault current limiters form an efficient category of current limiters. This type is expected to be studied and used widely in future due to their advantages. In this thesis, the first chapter reviews the superconductivity...
Enhancement of THz Radiation from Josephson Junctions in Superconductors Using Electromagnetic Resonators
,
M.Sc. Thesis
Sharif University of Technology
;
Ahmadi Boroujeni, Mehdi
(Supervisor)
;
Fardmanesh, Mehdi
(Supervisor)
Abstract
Terahertz waves which includes frequencies between 100 GHz to 10 THz of electromagnetic spectrum have found many applications in science, medical treatments and industry. One of the recent methods to produce these waves is using nonlinear properties of superconductors based on Josephson junctions which inherently appear in some superconductors called BSCCO. Stack of intrinsic junctions of these superconducting materials can radiate terahertz waves by only applying a DC voltage across them. This Thesis investigates some of these structures based on Josephson junctions to produce coherent radiation of terahertz waves. For the optimization of the radiation power, this study also investigates...
Water-energy nexus approach for optimal design of hybrid cooling system in direct reduction of iron plant
, Article Journal of Cleaner Production ; Volume 287 , 2021 ; 09596526 (ISSN) ; Morad Bazofti, M ; Akbari Mohammadi, A ; Mokhtari, H ; Saboohi, Y ; Golkar, B ; Ghandi, A. H ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Direct reduction of iron process in steel industry has special production conditions. Low quality cooling water, low cold and high hot cooling water temperature, space limitation for new equipment installation, high value-added of product and severe effect of cooling water temperature on production rate are of these conditions. Considering technical and economic constraints and limitations, this situation makes this process an attractive case study for converting the existing wet cooling tower to hybrid cooling system. In this paper, based on integration of process, dry and wet cooling system and ambient conditions profiles, a new method for designing hybrid cooling system has been proposed....
On the Spectrum of Modified Theories of Gravity
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mehdi (Supervisor) ; Sheikh Jabbari, Mohammad Mehdi (Supervisor)
Abstract
There are different approaches in modifications of General Relativity as the theory of gravity. The modified theories of gravity are important cases in this context, which mostly start by modifying the Einstein-Hilbert action, while keeping the general covariance. Within the modified theories of gravity, we consider two cases. The first is the f(R) theories of gravity, and the second is curvature squared theories of gravity with an action like S = ∫d4x pg( 116GR + (R)2 + R2 +(R)2). Curvature squared theories of gravity have interesting feautures, most important of which is renormalizability, in contrast with General Relativity. But this advantage, as noted by K.S. Stelle in 1977 comes at...
On Thermodynamics and Phase Space of Near Horizon Extremal Geometries
, Ph.D. Dissertation Sharif University of Technology ; Sheikh-Jabbari, Mohammad Mehdi (Supervisor) ; Golshani, Mehdi (Co-Advisor)
Abstract
Near Horizon Extremal Geometries (NHEG), are geometries which may appear in the near horizon region of the extremal black holes. These geometries have SL(2;R)U(1)n isometry, and constitute a family of solutions to the theory under consideration. In the first part of this report,their thermodynamic properties are reviewed, and their three universal laws are derived. In addition, at the end of the first part, the role of these laws in black hole thermodynamics is presented. In the second part of this thesis, we review building their classical phase space in the Einstein-Hilbert theory. The elements in the NHEG phase space manifold are built by appropriately chosen coordinate transformations of...
Critique and Survey of Various Formulation of Multiverse Theory
, Ph.D. Dissertation Sharif University of Technology ; Golshani, Mehdi (Supervisor) ; Sheikh Jabbari, Mohammad Mehdi (Supervisor)
Abstract
Multiverse scenario has been recently addressed by physicists and they have found it useful in many areas of physics. In this dissertation, I have treated some issues about multiverse such as the kinds of multiverses, the arguments for or against multiverse, areas in which multiverse is introduced, etc. This dissertation has six chapters and an appendix. In the chapter one, some classifications of multiverse is introduced, and also some definitions of the concept of a world is presented. Then, my classification and definition of a multiverse and a world is introduced. In the chapter two, the concept of possible worlds in philosophy and its relationship with multiverse hypothesis is examined....
Optimal Multicriteria Design of HTS Transformer and Construction of a Laboratory Scale Sample
, Ph.D. Dissertation Sharif University of Technology ; Vakilian, Mehdi (Supervisor) ; Fardmanesh, Mehdi (Co-Supervisor) ; Hekmati, Arsalan (Co-Supervisor)
Abstract
Employing high-temperature superconducting (HTS) tapes, instead of copper or aluminum wires for winding in a superconducting transformer, results in a series of significant advantages; such as: smaller volume, lighter weight, higher efficieny, greatly extended overload capability, better voltage regulation, lower life cycle cost, fault current limiting capability, lower environmental pollution and lower risk potential against fire hazards.In this thesis, optimal design of flux diverter using genetic algorithm for axial short circuit force reduction in HTS transformers has been performed. Then, multilayered flux diverters have been proposed for reduction of weight and losses. The impact of...
Analyzing Dermatological Data for Disease Detection Using Interpretable Deep Learning
, M.Sc. Thesis Sharif University of Technology ; Rabiee, Hamid Reza (Supervisor) ; Sharifi Zarchi, Ali (Supervisor) ; Ghandi, Narges (Co-Supervisor)
Abstract
We present a deep neural network to classify dermatological disease from patient images. Using self-supervised learning method we have utilized large amount of unlabeled data. We have pre-trained our model on 27000 dermoscopic images gathered from razi hospital, the best dermatological hospital in Iran, along with 33000 images from ISIC 2020 dataset. We have evaluated our model performance in semi-supervised and transfer learning approaches. Our experiments show that using this approach can improve model accuracy and PRC up to 20 percent on semi-supervised setting. The results also show that pretraining can improve classification PRC up to 20 percent on transfer learning task on HAM10000...
A Multi-Objective Robust Optimization Model for Logistics Planning in the Earthquake Response Phase [electronic resource]
, Article Transportation Research Part E: Logistics and Transportation Review, Elsevier ; Volume 49, Issue 1, January 2013, , Pages 217–249 ; Eshghi, Kourosh ; Dullaert, Wout ; Sharif University of Technology
Abstract
Usually, resources are short in supply when earthquakes occur. In such emergency situations, disaster relief organizations must use these scarce resources efficiently to achieve the best possible emergency relief. This paper therefore proposes a multi-objective, multi-mode, multi-commodity, and multi-period stochastic model to manage the logistics of both commodities and injured people in the earthquake response. Also, a robust approach is developed and used to make sure that the distribution plan performs well under the various situations that can follow an earthquake. Afterwards, it proposes a solution methodology according to hierarchical objective functions and uses it to illustrate the...
Monitoring of Valve Leakage in Internal Combustion Engine Using Acoustic Emission Method
, Ph.D. Dissertation Sharif University of Technology ; Behzad, Mehdi (Supervisor) ; Mehdigholi, Hamid (Supervisor) ; Ahmadi, Mohammad Mehdi (Co-Advisor)
Abstract
Valve leak detection is very important due to bad direct effects on parts life and engine power. Acoustic emission (AE) has a good known ability on leak detection between fault detection methods. The aim of this thesis is presenting the ability of AE method for valve leak detection in internal combustion engines. The research method in a general framework based on the idea that firstly some evaluations were done in static tests for leakage due to three faults including clearance, quasi-crack and notch. Then, the evaluations were continued with dynamic analysis of rotational speeds and different loads on the engine. Finally, the neural network approach was used to automatically detect all...
Evaluation of Electromagnetic Forces on three-phase Core-Type Power Transformer Windings during Inrush Current by FEM
, M.Sc. Thesis Sharif University of Technology ; Vakilian, Mehdi (Supervisor)
Abstract
Inrush Current is a form of over-current that occurs during energization of a transformer. For power transformers, the magnitude of the first peak of inrush current is initially several times the rated load current but slowly decreases until it finally reaches the normal exciting current value. This process typically takes several minutes. Time-variant axial and radial electromagnetic forces under inrush current and short-circuit current are calculated (by finite element method; FEM), and compared. An analytic method is presented for computation of inrush current in transformer. The simulation results obtained by this proposed method are compared with the measured values. A compact...
Relative Merits of the Two Famous Formulations of Bohmian Mechanics
, Ph.D. Dissertation Sharif University of Technology ; Golshani, Mehdi (Supervisor)
Abstract
The goal of this thesis is to evaluate the strengths and weaknesses of the two existing formulations of Bohmian mechanics. The first one was proposed by Bohm, and emphasizes on the dynamics being second-order, and in which, the key tool for explaining the quantum phenomena is a non-classical potential, called "the quantum potential". In this approach, the postulates of de Broglie's "pilot-wave" theory, which now is known as Bohmian mechanics, are non-fundamental and are special to the atomic level. The possibility is proposed that these postulates become subjected to some modifications at the nuclear or lower levels, but no particular way for performing such modifications is suggested. The...
Ground Water Denitrification by Packed Bed Bioreactor With KMT Packing
, M.Sc. Thesis Sharif University of Technology ; Borghei, Mehdi (Supervisor)
Abstract
In this study biological denitrification method by moving bed biofilm reactor is investigated. The main advantage of MBBR reactor is due to their capacity for high removal rates and low operational problems such as clogging. Two MBBRs in series with 3 liter volume each, were designed in experimental set up and used in this research. Nitrification reactor worked under aerobic conditions and denitrification reactor operated under anaerobic conditions. Methanol was used as carbon source in the reactors throughout the study. Fifty percent of each reactor volume was occupied with KMT1 packing. To finding the optimum nitrate loading rate, the concentration of ammonium and nitrate were changed from...