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farahbakhsh--mahdi
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Cross layering design of IPv6 fast handover in mobile WiMAX
, Article ICT 2010: 2010 17th International Conference on Telecommunications, 4 April 2010 through 7 April 2010, Doha ; April , 2010 , Pages 304-308 ; 9781424452477 (ISBN) ; Sorooshi, M ; Sharif University of Technology
2010
Abstract
Over the past few years, rapid advances in wireless broadband networks have been driving the evolution of communication and network technologies towards new mobile services for users. Handover management is still one of the most challenging issues to be solved for seamless mobility in wireless networks. To support mobility on terminal stations mobile WiMAX has been standardized. Moreover to provide seamless communications for such network Fast Mobile IPv6 (FMIPv6) has been proposed by IETF. But for seamless handover, collaboration of layer 2 and layer 3 is required. Thus, there is a requirement for cross-layering design to support proper behavior of the MIPv6 nodes in WiMAX networks. In this...
Scheduling of Operating Theatre Rooms Considering the Capacity of Post-Operating Rooms
,
M.Sc. Thesis
Sharif University of Technology
;
Salmasi, Nasser
(Supervisor)
Abstract
In this thesis, scheduling of surgery rooms is investigated and the objective is minimizing total patient’s departure time from the ward room in a flexible flow shop manner. Here, some constraints like the capacity of recovery rooms, no-wait motion between the rooms and machine eligibility restrictions ( , Σ ) are considered.For solving this problem,we proposed two mixed integer linear programming models for the research problem. Since the research problem is shown to be NP-complete, we developed several algorithm based on Tabu Search (TS) to heuristically solve it. In TS algorithm two different methods and one neighborhood structures are applied to generate initial solution and...
Dynamic Portfolio Optimization Using Other Investor’s Portfolios
, M.Sc. Thesis Sharif University of Technology ; Fazli, Mohammad Amin (Supervisor)
Abstract
Portfolio optimization is a crucial concept in financial engineering, focusing on the efficient management of investment portfolios. In the realm of financial markets, a portfolio refers to a collection of investments held by individuals or companies, encompassing diverse assets. Specifically, a stock portfolio consists solely of stocks. The primary objective of portfolio optimization methods is to maximize returns while controlling risks. Within Tehran’s Stock Market, valuable data pertaining to the stock portfolios of big shareholders and their historical changes can be obtained. This dataset contains vital information that can be leveraged to optimize portfolios over time and formulate...
Modeling of Error in Approximate Multipliers for Neural Network Accelerators
, M.Sc. Thesis Sharif University of Technology ; Sharifkhani, Mohammad (Supervisor)
Abstract
In recent years, Deep Neural Networks have become essential tools, surpassing human capabilities in various applications, leading to their widespread integration into various everyday applications. However, a fundamental challenge of these networks lies in their substantial energy consumption, particularly concerning constrained electronic devices. To address this issue, numerous solutions have been proposed, encompassing software-based approaches such as network pruning, knowledge distillation, and network quantization. Moreover, hardware-oriented enhancements have also emerged, including the utilization of approximate circuits and approximate calculations within neural network...
Optimal Control of Switched Systems
, M.Sc. Thesis Sharif University of Technology ; Mahdavi-Amiri, Nezam (Supervisor)
Abstract
We consider the problem of optimal control of switched systems. In order to solve this problem, by using the Lagrange interpolation, we transform it into an equivalent nonlocal optimal control problem, and then by applying several conditions we transform it into a moment problem. This way, a nonlinear and non-convex optimal control problem is converted to an equivalent optimal control problem with linear and convex structure, which allows us to obtain an equivalent convex formulation of the problem. So we obtain an approximation of the unknown function by using the Lagrange interpolation, and an approximation of the integral term by using the trapezoidal method. Finally, we solve the problem...
Modeling Cesium-137 Deposition and Absorption on Soil and Plants
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor) ; Movafeghi, Amir (Co-Advisor) ; Yahagi, Effat (Supervisor)
Abstract
Cesium-137 is one of the more important radionuclides in the environment because it is relatively abundant, it has a moderately long half-life (~30 y), its decay produces highly penetrating gamma radiation in addition to beta particles, and its biogeochemical properties allow it to move readily through food chains. It is a radioactive isotope of cesium which is formed as one of the more common fission product by the nuclear fission of uranium-235 and other fissionable isotopes in nuclear reactors and nuclear weapons.
In this reseach a model is introduced that could simulate a nuclear accident, its distribution into air, deposition into soil and absorption by plant. Nuclear accident and...
In this reseach a model is introduced that could simulate a nuclear accident, its distribution into air, deposition into soil and absorption by plant. Nuclear accident and...
MBBR and MBR Reactor Configuration for Better Performance
, M.Sc. Thesis Sharif University of Technology ; Borgheei, Mahdi (Supervisor)
Abstract
Membrane bioreactors (MBRs) which are commonly understood as the combination of membrane filtration and biological treatment using activated sludge have several advantages, but membrane fouling reduces the membrane efficiency, permeability and lifetime. An alternative is replacing a moving bed biofilm reactor (MBBR) with the activated sludge system which may reduce the effect of membrane fouling. The sludge produced in MBBRs has poor settling characteristics, therefore, their efficiency is limited by the sedimentation tank performance and they require a larger settling surface. The combination of moving bed biofilm reactors and membrane bioreactors can compensate for the drawbacks of both of...
Forecasting the effects of a Canada-US currency union on output and prices: A counterfactual analysis
, Article Journal of Forecasting ; Volume 32, Issue 7 , 2013 , Pages 639-653 ; 02776693 (ISSN) ; Sharif University of Technology
2013
Abstract
This paper is a counterfactual analysis investigating the consequences of the formation of a currency union for Canada and the USA: whether outputs increase and prices decrease if these countries form a currency union. We use a two-country cointegrated model to conduct the counterfactual analysis, where the conditional forecasts are generated based on the Gaussian assumption. To deal with structural breaks and model uncertainty, conditional forecasts are generated from different models/estimation windows and the model-averaging technique is used to combine the forecasts. We also examine the robustness of our results to parameter uncertainty using the wild bootstrap method. The results show...
What is it to be Physical?
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mahdi (Supervisor)
Abstract
In this text to find the answer of the question “ what is it to be physical” in a definition form or a scheme of the term physical, firstly we sought for a possible consensus among recent physicists and philosophers. But from their answers not only we did not find any clear consensus but also most of them confess that the term is ambiguous and unclear. In a general aspect, we can categorize the answers to two theoretical and realistic perspective. The theoretical perspective, beside circularity and Hempel’s triviality, seems not to present any criteria for being physical. In realistic perspective, it seems that there is no ontologic constraint for being physical, that is from “being...
Biomass Separation in Moving Bed Biofilm Reactors (MBBR) by Natural And Innovative Filters
, M.Sc. Thesis Sharif University of Technology ; Borgheei, Mahdi (Supervisor)
Abstract
The application of membranes for separate of particles in mainly microbial flacs , are fast growing in biological treatment systems. Membrane bioreactors are now considered as one of the major new processes in wastewater treatment. However , membranes are expensive and costly. This study is carried out to test an innovative , locally made filters for separation of flocs in an MBBR reactor. This innovative filter is replacing a traditional settling tank. This type of filters is made very cheaply and has important advantages in installing and operation. Experiments were carried out in a laboratory scale MBBR unit. A filter unit consisting of 3 innovative filter tubes were placed and the...
Dynamic Security Assessment in Restructured Power Systems
, Ph.D. Dissertation Sharif University of Technology ; Ehsan, Mahdi (Supervisor)
Abstract
This thesis addresses the problem of dynamic security assessment in power sys-tems with an emphasis on its application in restructured power systems and issues arising in its applications. The new electric utility environment has an immedi-ate consequence of emphasis on reliability and secure operation of power systems. This requires faster and more precise methods to assess the dynamic aspect of se-curity. On the other hand, this issue is becoming challenging when the determined dispatch might not be accommodated due to violation of the limits.This thesis addresses the problem of dynamic security assessment in power sys-tems with an emphasis on its application in restructured power systems...
A Study on the Impact of the “Commodities’ Returns"on the Related “Firms’ Stock Returns” in Tehran Stock Exchange
, M.Sc. Thesis Sharif University of Technology ; Barakchian, Mahdi (Supervisor)
Abstract
Are the returns of the mineral companies in Tehran Stock Exchange affected by the changes in the commodity price at the Iran Mercantile Exchange? By implementing a Multi-Factor Model we will calculate the firms’ value elasticity to the commodity price changes. We try to explain the estimated elasticities on the basis of the firm’s fundamental variables using a discounted cash flow valuation model. An unbalanced panel data estimation is employed for this purpose. Afterwards, we will suggest a novel model on the ground of the assumption that the commodity prices and firm values follow the Geometric Brownian Motion. The result of the model is that the elasticity can be explained by commodity...
Analytical and Finite Element Modeling of Rubbing Phenomena in Rotors
, M.Sc. Thesis Sharif University of Technology ; Behzad, Mahdi (Supervisor)
Abstract
Rotor contact with a stationary element of a rotating machine and the subsequent rubbing at the contact area is a serious malfunction that may lead to the machine’s catastrophic failure. In the past decades, many studies have been done on the rubbing phenomena, its different regimes and its various consequences on the machine performance and safety. However, most of them have used a simple model to investigate the rubbing interaction between the rotor and the stator. This simple model consists of the Jeffcott rotor, as a model for the real rotors, and a rigid annular block surrounding the rotor, as a model for the real stators. The objective of this thesis is to build an algorithm to...
Failure Tolerance of Epidemic Spreading in Complex Network
, M.Sc. Thesis Sharif University of Technology ; Jalili, Mahdi (Supervisor)
Abstract
Complex networks serve as generic models for many social, technological and biological systems that have been shown to share a number of common structural properties such as power-law degree distribution and small-worldness. These networks determine interactions and influence the spread of diseases, behaviours and ideas. Epidemics and failures like new behaviours ideas and innovations can spread throughout a network and prevent it from doing its functionalities. In this work, we investigate error and attack tolerance of epidemic spreading in complex networks. The main content of this thesis is arranged in three sections as follows: Firstly, the effect of random and systematic failures is...
Evaluation of Non-linear Combination Method (Neural Network) For Value-at-Risk Forecasting in Market
, M.Sc. Thesis Sharif University of Technology ; Barakchian, Mahdi (Supervisor)
Abstract
Value at risk of an asset, is the asset’s expected maximum loss for a certain period of time and at a specified confidence level. Value-at-Risk can be calculated in the bank with its inter-nal method or standardized method. when a method have more violation number then bank need to keep more daily capital requirements. under the Basel 2 agreement if the violation of method more than 10 times in year, the Bank uses the standardized method.
There are trade off Between daily capital charge and violations. Therefore, existing methods for calculating the value at risk, usually lead to much daily capital charge or many violations. Studies show with combination of different methods to calculate...
There are trade off Between daily capital charge and violations. Therefore, existing methods for calculating the value at risk, usually lead to much daily capital charge or many violations. Studies show with combination of different methods to calculate...
Differences Between Standard Quantum Mechanics and Bohm's Quantum Mechanics
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mahdi (Supervisor)
Abstract
The purpose of introducing this thesis is to review the difference between Standard Quantum mechanics and Bohmian Quantum mechanics. The aim of this dissertation is not only to contrast these theories with respect to formulation, but also to briefly review their historical, philosophical and sociological aspects. This dissertation consists of two main sections. The first section is about reviewing the emergence profile of these theories and the formation of each theory along its historical path. In addition some beliefs about the founders of these theories and the impact of their beliefs on the evolution of their theories are put forward. As a complement to the above, the prevailing social...
Evaluation of Caviar Models Incorporated with Intraday Information ,the Case Study:Estimation Value at Risk of Gold
, M.Sc. Thesis Sharif University of Technology ; Barakchian, Mahdi (Supervisor)
Abstract
Value at risk (VaR) is the maximum loss of the asset portfolio at the specified confidence level and certain time horizon. This tool is used to measure market risk and also used as a basis in determining financial standards for international financial instituation. Conditional Autoregressive Value at Risk models or CAViaR models introduced by Engle and Manganelli (2004). This models calculate VaR base on quantile regession approach and show some promising performance properties.
In order to propose a more accurate model for calcutating VaR , we develop CAViaR models by incorporating them with intraday information then we calculate VaR with this kind of models and CAViaR...
In order to propose a more accurate model for calcutating VaR , we develop CAViaR models by incorporating them with intraday information then we calculate VaR with this kind of models and CAViaR...
Design and Implementation of a Spectrum Sensor for Cognitive Radio
, M.Sc. Thesis Sharif University of Technology ; Shabani, Mahdi (Supervisor)
Abstract
Frequency scarcity has emerged the necessity of opportunistic utilization of frequency bands, which can be realized through a cognitive radio system. During an agile communication between unlicensed users, a cognitive radio system must avoid collision with licensed users. Hence it should continuously observe the band of interest and report the presence of licensed user signals. This task is fulfilled by a vital part of a cognitive radio system, called the spectrum sensing core. Recently several techniques have been proposed for the spectrum sensing in literature. Some of them like matched filtering, cyclostationarity based detection are based on primary user signal features. However energy...
Learning Improvement in Phase Oscillator Models
, M.Sc. Thesis Sharif University of Technology ; Jalili, Mahdi (Supervisor)
Abstract
In the recent years, the problem of modeling a cognitive task using phase oscillators has been receiving a significant attention. In this view, single neurons are no longer elementary computational units. Rather, coherent oscillating groups of neurons are seen as nodes of networks performing cognitive tasks. From this assumption, we develop a model of stimulus-response learning and recognition. The most significant part of our work is defining learning methods for natural frequencies and coupling weights in a coupled phase oscillator network under Kuramoto conditions. In this thesis, we improved the previous models by not only emphasizing on the frequency of the oscillators but also taking...
EEG Brain Functional Network Analysis in Cortex Level
, M.Sc. Thesis Sharif University of Technology ; Jalili, Mahdi (Supervisor)
Abstract
Complex networks science have received tremendous attention in recent years and the brain is one of the systems to which graph theoretical tools have been applied. Alzheimer’s disease (AD) is a neurodegenerative disease affecting many of elderly population. AD changes the anatomy of the brain, which subsequently results in changes in its functions. These changes have been frequently reported in signals recorded from the brain (such as MEG, fMRI and EEG). Among these neuroimaging techniques EEG is one of the most aproprate methods for extracting functional connectivites according to high temporal resolution. In this thesis, we aimed at analyzing the properties of EEG-based functional networks...